Annual World Conference on Carbon - Carbon 2013 (Carbon 2013)

Rio de Janeiro, Brazil, 14-19 July 2013


3
Surface reconstruction of microcrystalline diamond: a photoelectron energy loss spectroscopy study
Christian GODETa,*, Denis G.F. DAVIDb, Marie-Amandine PINAULT-THAURYa, Dominique BALLUTAUDa
a CNRS, France
b Universidade Federal da Bahia, Brazil

While X-ray Photoelectron (XPS) core level spectra are commonly used for chemical analysis of thin film surfaces, the distribution of photoelectron energy losses (surface and bulk plasmon excitation, interband transitions) contains useful information related to the near surface dielectric function ε(hω). The sensitivity of Photoelectron Energy Loss Spectroscopy (PEELS) to surface reconstruction of diamond is investigated in a well-controlled system, namely boron-doped microcrystalline films with a mixture of (111) and (100) preferential orientation, used either as-grown (partially hydrogenated surface) or after annealing (1150°C) in ultra high vacuum. While the bulk (σ+π) plasmon of diamond at 34 eV is weakly attenuated, characteristic features appear at 11 and 19 eV in the loss distribution after annealing. In order to propose an interpretation to such observations, the dielectric theory was used to calculate bulk and surface plasmon distributions, respectively proportional to Im[-1/ ε()] and to Im[(1/ε()) – (4/1+ε())], where ε(ω) is the dielectric function. The calculated results for crystalline diamond and for graphite (ordinary index) show that the 11 eV and 19 eV losses are well described by simulation of surface plasmon excitation in graphitic materials ; they also coincide with experimental interband losses in graphene layers. This work shows that PEELS measured with standard XPS equipment is sensitive to diamond surface reconstruction after UHV annealing even in the absence of graphitization.



4
Use of Coal-based Feedstock to make Mesophase Pitch for Graphite Artifacts Part II: Solvent Extraction Route
John C. Chang, T. A. Pirro
GrafTech International, Parma Technical Center, Parma OHIO 44130 USA

A study was performed to investigate the use of coal derived feedstock for producing mesophase pitch. Coal-tar distillate was transformed to mesophase pitch by using a high pressure batch-scale autoclave. We had reported previously (Part I) the results from the Thermal Route to produce mesophase pitch from coal tar distillates and graphite artifact derived from it. In this Part II report, we will present the second and different method, the Solvent Extraction Route, to produce mesophase pitch. The comparisons between these two routes will be presented in terms of production yields and mesophase pitch characterizations and quality. Example of graphite artifacts made from thermally-produced and solvent-extracted mesophase pitches are characterized and presented.



9
Simple and versatile one-step synthesis of highly interconnected graphitized macroporous carbon foam
Mani Karthika,*, Doppiu Stefaniab
a Postdoctoral researcher
b Group Leader

The highly interconnected graphitized macroporous carbon foams were successfully synthesised by one-step low temperature process using resorcinol and formaldehyde as carbon precursors and metal nitrate as a graphitization catalyst. The commercially available polyurethane foam was used as a sacrificial polymer template. The obtained three-dimensional (3D) highly interconnected graphitized carbon foams were extensively characterized by using powder X-ray diffraction (XRD), nitrogen adsorption-desorption measurement, transmission electron microscopy (TEM), scanning electron microscopy (SEM), raman spectroscopy and thermogravimetric analysis (TGA). XRD and TEM results clearly demonstrated the presence of a well-defined graphitic framework. The surface morphology of the macroporous carbon foam was studied by using SEM and the results clearly showed the presence of a highly interconnected porous network throughout the structure. The thermal stability of the carbon foam was also examined by TGA. The effects of various parameters such as precursor ratio, curing time & temperature, concentration of the metal nitrate and graphitization temperature were investigated. The physical properties of the carbon foam as such density, pore size and total porosity were also studied and the salient results are discussed.



10
Linking graphite particle micro-structure and reactivity
Heinrich Badenhorst
SARChI Carbon Chair, University of Pretoria
Synthetic graphite is an important industrial material and is used in many high temperature applications, ranging from structural and moderator components in nuclear reactors to electrodes for arc furnaces in the steel production industry. Thus, knowledge of the high temperature oxidative behavior of graphite is essential for understanding any structural changes which may occur due to oxidation during accidental air-ingress situations or degradation during normal operation. Synthetic graphite is produced via a multi-step, re-impregnation process resulting in very complex micro-structures and porosity. In general though, graphite is considered to be a fairly simple and well understood allotrope of carbon. It is assumed to be comprised of layered planes of hexagonally bonded carbon atoms with crystallites of varying sizes and thickness. However, the closest approximation to this ideal structure can only be found in mined natural graphite flakes. Despite the complexity and large property variations found in graphitic materials, kinetic investigations are routinely conducted on graphite samples from different sources and origins, without any examination of the material micro-structure. The aim of this paper is to demonstrate the necessity of visually inspecting the micro-structure of graphite materials both before and during oxidation. The micro-structure not only demonstrates the complex development of the surface area during oxidation but also highlights the presence of trace impurities and exposes the underlying crystallinity. All of these factors are critical when attempting to compare the oxidative reactivity of graphite samples from different sources and origins. Especially in cases where the exact history of the material is not known. Simply analysing the purity or ash content is not enough due to the considerable impact extremely low levels of impurities have on the oxidation rate. Furthermore, the use of X-ray diffraction to determine the crystallinity is shown to be an inadequate representation of the observed behavior.


11
The Synthesis of Hierarchical and Ordered Porous Carbon Materials
jiangtao caia,*, xiaoyan lia, guoyang liub, jieshan qiuc, anning zhoua, et al.
a Xi’an University of Science and Technology, Xi’an, China
b Xi’an University of Science and Technology, Xi’an , China
c Carbon Research Laboratory, Liaoning Key Lab for Energy Materials and Chemical Engineering, Dalian University of Technology, Dalian ,China

Key words: Macroporous; Mesoporous; Template agent; Carbon materials; Phenolic resin

The porous carbon materials have a very wide range of applications because of their controllable pore structure, excellent thermal stability and chemical stability, surface chemical inertness [1-3]. The hierarchical macro-mesoporous carbon (HMMC) materials are more attractive for their unique catalytic and adsorption properties due to the contribution of the mesoporous structure and the quick mass transportation features due to the macroporous structure [4-6]. Here we report on the synthesis of HMMC by a dual-template method with a resole resin as the carbon precursor, F127 and P123 as mesoporous template agent, and poly-styrene colloidal crystal array as macroporous template agent, followed by the ethanol solvent evaporation induced self-assembly process and a temperature-programmed carbonization. The morphology and microstructure of the as-made products were characterized by FESEM, XRD, and physical adsorption instrument. In this paper we mainly studied the effect of the above template agent types, the dosage, the combination mode of carbon source and template agent etc. on the pore size distribution, pore size and specific surface area of the HMMC.

The results show that ordered mesoporous carbon materials are formed due to the synergetic interaction and combining effect of the two templates F127 and P123, of which the order of mesoporous can be improved by increasing the template amount to some degree, but excessive amount will affect the stability of the macroporous. The carbonaceous material prepared in the different assembly methods, such as template agent were assembled with the monomer in situ polymerization, or assembled with the prepolymer, the latter is more conducive to the mesoporous structure orderly formation than the former. The vinyl on polystyrene has affinity with the mesoporous template agent that is a ternary block copolymer, which were beneficial to the orderly arrangement of mesoporous. The as-made HMMC products have large pores of 200 nm and mesopores of 8 nm and 3 nm, and the pore volume of 0.527 cm3/g , the BET surface area of 510m2/g.

Acknowledgements:

This work was partly supported by National Natural Science Foundation of China (No.21276207), the Key Program of Ministry of Education of China (No.212175), and the Scientific Research Foundation of Xi'an University of Science and Technology (No. 2010019).

References:

[1] Ryoo R, Joo S H, Kruk M, et al. Adv. Mater. 2001,13(9):677.

[2] Zakhidov A A, Baughman R H, Iqba1Z, et al. Science1998,282(5390):897.

[3] Zhao D Y, Yang P D, Chmelka B F, et al.Chem. Mater.1999,11(5):1174.

[4] Michio Inagaki. New Carbon Materials, 2009.24(3):193.

[5] Deng Y H, Liu C,YuT, et al. Chem.Mater.2007,19(13):3271.

[6]Wang Z Y, Kiesel E R, Stein A. J.Mater.Chem. 2008,18(19):2194.



12
Research of using F127 as the soft template for preparation of PAN-based mesoporous carbon materials
xiaoyan lia,*, jiangtao caia, jieshan qiub, anning zhoua, yating zhanga, et al.
a Xi’an University of Science and Technology, Xi’an , China
b Carbon Research Laboratory, Liaoning Key Lab for Energy Materials and Chemical Engineering, Dalian University of Technology, Dalian,China

KeywordsF127,Mesoporous, Carbon materials, Polyacrylonitrile

Mesoporous carbon materials have been widely used in many fields including adsorption separation, catalysis, energy storage, and nano-electronic devices [1-4] as a result of their developed pore structure that can be continuously tuned to a great degree. Polyacrylonitrile (PAN), a nitrogen-containing carbon precursor, is a very good candidate for making mesoporous carbon materials with different surface functionalities [5-6]. In this presentation, PAN fibers were used as the carbon source and mixed with a ternary block copolymer (F127) to make PAN-based mesoporous carbon materials by some techniques, involving the assembly of F127 and the PAN, the pre-oxidation, the carbonization and the activation steps. The char yield, graphitization degree, degree of order of mesoporous, surface morphology and microstructure of the products were characterized via FESEM, XRD, and element analysis and nitrogen adsorption techniques.

The results show that mesoporous carbon materials with ordered mesoporous structure can be produced when the ratio of PAN (carbon source) to F127 (template) is at 7:3. The char yields decreases gradually with the increase in the F127 amount, nevertheless, the graphitizetion degree of the concerned carbon materials changes little, though the activation can greatly change the surface area of the carbon materials. Under the optimum conditions adopted in the present work, mesoporous carbon materials with a BET surface area of 912 m2/g, an average pore size of about 3nm, a nitrogen content as high as 9.8wt.% can be made in a char yield up to 48.2 wt.%. It is believed that mesoporous carbon materials with larger surface area, welldeveloped yet ordered mesoporous structure, and high heteroatom nitrogen content will be attractive in fields such as adsorption, catalysis and energy storage and conversion.

Acknowledgements

The authors are grateful for National Natural Science Foundation of China (No.21276207), the Key Program of Ministry of Education of China(Program No.212175), and the Scientific Research Foundation of Xi'an University of Science and Technology (No. 2010019).

References:

[1] Vinu A, Streb C, Murugesan V, et al. J. Phys. Chem.,2003,107(33):8297.

[2] Lu A H, Schmidt W, Matoussevitch N,et al. Angew. Chem.,2004, 43(33):4303.

[3] Tanaka S,Nishiyama N,Egashira Y,et al.Chem.Commun.,2005,(16): 2125

[4] Meng Y,Gu D,Zhang F,et al. Angew.Chem.Lnt.Ed.,2005,117(43):7215

[5] Kim W Y, Joo J B, Kim N D,et al.Carbon, 2009, 47(12):1407

[6] Liu G, Li X G, Ganesan P, et al. App. Catal. B: Environ., 2009,93(1-2):156



13
Carbon Recovery from Coal Combustion Wastes to Reduce Negative Environmental Effects
Derya Oz Aksoya, Sabiha Kocaa, Huseyin Kocab,*
a Osmangazi University, Mining Engineering Department, 26480, Eskişehir, Turkey
b Anadolu University, Porsuk Technical College, 26470, Eskişehir, Turkey

The ratio of coal usage in general primary energy consumption is currently over 25 % in Turkey. It is expected to increase up to 40 % in 2020, as coal reserves are far more abundant than other energy resources. As a result utilization of coal in energy production is proposed to expand from 70 million tons in 2010 to over 180 million tons in 2020. Turkish coals typically have ash content of 30-60 % and low calorific value. Therefore over 20 million tons of coal combustion wastes are produced each year. Coal combustion wastes are held in large dams which results in hazardous impact on the environment, polluting soil and ground water. It is therefore to obtain permits and land for a new dam is expensive and not always possible. A landfill tax has been introduced or landfilling of organic waste has been completely stopped in some countries. The European Community introduced directives for environmental immunity and promotion of environmental management systems. In the course of achieving proper waste management, a waste hierarchy is proposed in waste management systems. In most cases the following order is suggested: Reduce the amount of waste, reuse, recycle material, incinerate with heat recovery, finally landfill.

Coal combustion wastes consist of mainly unburned carbon and inorganic compounds (such as: silica, alumina, iron oxides, magnesium oxide, phosphorus oxide etc.) These inorganic materials are valuable substances and can be utilized in many industries such as cement manufacture, ceramic making, waste water treatment, extraction of valuable minerals.

The utilization of coal combustion wastes is not as high as expected; only 33% of them are utilized in cement industry. The rest is simply landfilled to the nearby dams. The main reason for low utilization rate is the unburned carbon content of coal combustion wastes. The ASTM C618 specification limits the unburned carbon content to 6 %. It has been reported by many authors that coal combustion wastes in Turkey may contain as high as 15 % unburned carbon. In order to increase the possibility of usage of these wastes, the unburned carbon should be separated. This carbon enriched fraction can be utilized as an energy sources.

Coal combustion waste samples, taken from Tuncbilek Power Plant waste dams, include over 14% unburned carbon. The samples were subjected to flotation experiments to obtain carbon enriched fraction that can be fed to the power plant boilers. The residues are possibly utilized in cement industry. In the flotation experiments particle size distribution, collector and frother type were tested as variables. At optimum conditions, the carbon content of the concentrate increased over 47 %. This fraction can be blended back into the coal feed to the power plant boilers. The carbon content of the tailings fraction was decreased to less then 6%. This fraction can readily be used in the cement industry.



14
Cleaning of Lignite Fines from Canakkale-Can Region Lignite Deposits
Ayse Erdema, Akan Gulmeza, Oguz Altuna, Zeki Olgunb, Sabiha Kocac,*, et al.
a General Directorate of Mineral Research and Exploration, Ankara, Turkey
b Turkish Coal Enterprises, Ankara, Turkey
c Osmangazi University, Engineering Faculty, Mining Engineering Department, Eskisehir, Turkey

Over 90 % of the Turkish lignite reserves contain high levels of ash and sulphur which causes considerable environmental pollution due to particulate matter and SOX emissions when these materials are combusted in lignite fired power generation stations. It is therefore countries and international organizations have long introduced legislations against environmental pollutions. These lignites have to be cleaned if they are utilized in energy production. Physical, chemical and biological methods are available to clean coal before combustion. Among these, physical methods are most preferred because of their cheapness and easy operation processes. The particle size of lignite is the major limiting factor in physical cleaning. Sulphur minerals in lignite are generally finely disseminated, and liberation can only be obtained by fine grinding. On the other hand conventional physical separation methods employed in coal washing plants are unable to recover fine particles. In order to improve the recovery of fine lignites and, at the same time, reduce the levels of ash and sulphur content significantly, comparatively a new physical cleaning device in coal cleaning, Multi Gravity Separator (MGS), has been investigated.

MGS was originally designed for fine metallic mineral concentration in 1990’s, then was successfully applied to fine coal cleaning.

Canakkale-Can Lignites Company, which is located in the North-west of Turkey, has over 80 million tons of reserves and produces nearly 2 million tons of lignite annually. Run of mine lignites are fed to the preparation plant where they are crushed and sized to minus 10 mm without any washing. All of this production is supplied to the nearby power plant for electricity generation.

In this work, cleaning of Canakkale-Can Region lignite fines was carried out by Multi Gravity Separator. The combinations of washwater flowrate and drum speed of the MGS were studied to optimize the best separation conditions. The other experimental conditions such as shake frequency, shake amplitude, feed rate and tilt angle of the drum were kept constant.

The lignite samples were collected from Canakkale-Can Lignite Preparation Plant feed. The sample contains over 45 % ash, 5 % total sulphur and around 2550 Kcal/kg lower calorific value. Samples were dried in open air and ground to minus 0.300 mm. After preliminary MGS experiments, encouraging results were obtained as over 50 % reduction in ash and over 25 % reduction in total sulphur content was noted with 80 % combustible recovery. Further improvements in ash and total sulphur reduction can be obtained by optimizing other operating conditions. It was also concluded that a further enhancement in ash and sulphur reduction in the product could be obtained by incorporating a cleaner stage.



15
Speciality Cokes from Coal Tars: A combined solution for graphite electrodes and Al cathodes
Perruchoud Raymond
R&D Carbon Ltd

There is a growing demand from the steel industry for super premium needle cokes requested for the UHP arc furnaces producing electrical steel. The strong increase of the Al consumption and the switch to graphitized cathodes in the Al smelters raise dramatically the consumption of hard isotropic coke for this application. China and India where the growth rate in steel and Al exceed two digits face a challenging situation for the supply of high quality cokes for both carbon electrode applications. For instance the majority of premium needle coke is still imported in both countries and there is no production of needle cokes in India.

The lack of significant production of the above mentioned type of cokes in the petroleum refineries is related to the scarcity of low S decant oil generated by FCC units and to the lack of high asphaltene resids that are the preferred delayed coker feedstock for the production of relatively isotropic hard coke used for graphitized cathode.

Specialty pitch cokes have been produced since decades in Japan and more recently a pitch needle coke project in South Korea has been announced. Both countries are major pig iron producers and can use the coal tar by-product from the coke production as feedstock in delayed cokers. The pig iron production is reaching in 2012 more than 700 mt in China and 40 mt in India. In China more than 500 mt and in India about 30 mt of coal was needed for covering the metallurgical coke consumed by the blast furnaces. With an average 3.3 % coal tar by product rate, the amount of coal tar exceeded 15 mt in China and reached 1 mt in India. The percentage of coal tar distilled for the production of pitches used in the domestic carbon industry reached only 20 % in China and 40 % in India. A significant proportion of coal tar binders are exported especially from India, however with mitigate economics. Latin America (mainly Brazil ) and CIS have a significant amount of coal tar surplus as well.

The economics of tar distillers producing coal tar pitch can be massively improved when specialty cokes instead of binders are produced. Therefore the production of soft and hard cokes out of coal tar for, respectively, the graphite electrode and cathode applications represents an opportunity for the tar distillation but also for the users in the carbon industries.

The technical and economical aspects of the production of specialty pitch cokes are addressed along with forecast of the demand resulting from a market study. Innovative process for a balanced production of both type of cokes are discussed along with the impacts on the end-products performances that were tested at the electrode pilot scale and research laboratories.



16
Influences of Silanized Carbon Nanotubes on the Properties of Polyamide Nanocomposites
Cevdet KAYNAK, Secil SANKAL
Materials and Metallurgical Engineering Department, Middle East Technical University (METU), Ankara, Turkey

The first aim of this work was to investigate usability of various characterization techniques for certain aspects of surface functionalized multi-walled carbon nanotubes. Surfaces were first oxidative functionalized by sulphuric acid/nitric acid mixture, then aminosilanized by aminopropyltriethoxysilane. Chemical groups formed on carbon nanotubes due to these surface treatments were characterizedg by X-ray Photoelectron Spectroscopy, Fourier-Transform Infrared Spectroscopy and also Energy Dispersive Spectroscopy. Morphological changes and crystal structure of surface treated carbon nanotubes were analyzed by Scanning Electron Microscopy and X-ray Diffraction, respectively. Thermogravimetric Analysis was also used to observe thermal degradation of the chemical groups formed on the nanotube surfaces.

The second aim was to reveal the influences of oxidative functionalized and aminosilanized carbon nanotubes on the mechanical and thermal properties of polyamide-6 nanocomposites. Nanocomposites were compounded by melt mixing technique and shaped by injection molding. Scanning and transmission electron microscopy images revealed that functionalized and aminosilanized carbon nanotubes were dispersed more evenly due to increased interactions with the matrix. Flexural tests revealed that strength and modulus values could be increased as much as 30% and 40% respectively, while tensile tests indicated that yield strength and Young’s modulus of nanocomposites increased 20% and 23% respectively, with only 1 wt% aminosilanized carbon nanotubes due to very efficient load transfer from the matrix to covalently bonded carbon nanotubes. Both dynamic mechanical analysis and thermogravimetric analysis showed that surface modified carbon nanotubes improve all thermal properties due to decreased matrix mobility and physical barrier formation. For example, increases in the storage modulus values were as much as 25%, while the increase in the thermal degradation temperatures were as much as 5°C in the specimens with only 1wt% aminosilanized carbon nanotubes.



17
Non-Covalent Functionalized Graphene Foam as Electrode for Supercapacitors
Abdulhakeem Bello, Fabiane Mopeli, David Dodoo-Arhin, Manyala Ncholu
Department of Physics Institute of Applied Material Univerist of Pretoria South Africa
We describe a simple and scalable technique to synthesize graphene foam using chemical vapour deposition (CVD) and nickel foam as the template for the growth of graphene. Non covalent functionalization of the graphene foam (GF) was performed using 1-pyrene carboxylic acid. This method of functionalization prevents the distortion of the sp2 honey comb lattice of the graphene, resulting in good quality crystalline samples (defect free). Morphological characterization reveals that the functionalized sample consists of densely packed honey comb flower structures. Symmetric electrochemical double layer capacitor of the functionalized foam was fabricated and found to demonstrate a good capacitive performance.


18
Synthesis and Characterization of Graphene Foam-metal oxide Composite for Electrochemical Applications
Ncholu Manyalaa,*, Abdulhakeem Belloa, Fabiane Mopelia, David Dodoo_Arhina, Kenneth Ozoemenab
a Department of Physics, Institute of Applied Materials, SARCHI Chair in Carbon Technology and Materials, University of Pretoria
b Council for Scientific and Industrial Research, Pretoria South Africa, Meiring Naude Road, Brummeria, 395 Pretoria, 0001, South Africa
The increasing demand for renewable and sustainable energy resources has intensified research activities for the development of energy storage systems that can meet future power requirements. Graphene, a two-dimensional honeycomb lattice of sp2-bonded carbon atoms, has emerged and is being considered an ideal additive material for improved electrochemical charge storage application. This is because of its theoretical high surface area (2630m2g-1), high electrical conductivity, chemical stability and excellent mechanical properties. More recently, the development of supercapacitors electrode materials has been focused on nanostructures composite of graphene and metal oxides. In this work we present supercapacitor device based on composite of graphene foam (GF) and metal oxide nanostructures highlighting the synergistic effects between graphene and metal oxides for improved electrochemical performance.


19
Processing Lignocellulosic Biomass via Hydrothermal Carbonization
Magdalena Titirici
Queen Mary University of London

During hydrothermal upgrading, biomass is treated for short times under subcritical conditions to give a heavy organic liquid with a heating value of 30-35 MJ/kg. While most research groups want to avoid the formation of a solid known under the name of “humin”, Titirici´s group is using this exact process for the production of green and valuable carbon materials.

Hydrothermal carbonization of biomass represents a mimic of “coal formation” shifting the time scale from millions of years to few hours. This makes this process a considerable alternative to other currently discussed carbon sequestration techniques.

The resulting biomass-derived coal obtained from hydrothermal carbonization of biomass (HTC) can then be used as biochar in soil. Furthermore, the resulting HTC is expected to exhibit favourable behavior with respect to combustion, gasification, and other thermal conversion processes for decentralized applications.

The group of Dr. Titirici has intensively studied the application of HTC in various fields such as rechargeable batteries, supercapacitors, fuel cells, water purification, gas storage and catalysis where HTC proved a to be a green and low-cost alternative surpassing the performance of other carbon counterparts.

During hydrothermal carbonization of biomass, 20-30% of the initial carbon content stays in the liquid phase which can then be further processed into important products and biofuels using the solid HTC as an efficient catalyst.

Thus, hydrothermal carbonization of biomass represents an economical and viable alternative to biomass processing into useful materials and liquid fuels, at the same time capturing the CO2 from the biomass precursor.

References:

  1. M. M. Titirici, R. J. White, C. Falco, M. Sevilla: Black perspectives for a green future: hydrothermal carbons for environment protection and energy storageEnergy. Environ. Sci., 2012, 5, 6796
  2. B. Hu, K. Wang, L. Wu, S. H. Yu, M. Antonietti, M. M Titirici: “Engineering Carbon Materials from the Hydrothermal Carbonization Process of Biomass” Adv. Mater. 2010, 22, 1
  3. M. M. Titirici, M. Antonietti: “Chemistry and materials options of sustainable carbon materials made by hydrothermal carbonization” Chem. Soc. Rev. 2010, 39, 10


20
A Sustainable Production of Porous Carbon Monoliths using Hydrothermal Carbonization
Magdalena Titiricia,*, Robin Whiteb, Nicolas Brunc, Shiori Kubod
a Queen Mary University of London
b TU Berlin
c Max-Planck Institute of Colloids and Interfaces
d AIST Japan

The creation of new and very importantly greener industries and new sustainable pathways are crucial to create a world in which energy use needs not be limited and where usable energy can be produced and stored wherever it is needed.

New materials based on carbon, ideally produced via inexpensive, low energy consumption methods, using renewable resources as precursors, with flexible morphologies, pore structures and functionalities, are increasingly viewed as ideal candidates to fulfil these goals. The resulting materials should be a feasible solution for the efficient storage of energy and gases.

Hydrothermal carbonization (HTC)1 is an ideal technology for the production of such low-cost but highly performing materials out of the most abundant renewable resource on the planet, i.e. lignocellulosic biomass.

In this presentation we would like to present our latest results on the production of well-defined porous carbon monolithic materials using biomass derivatives and HTC.

Carbon monoliths with various hierarchical pore structures can be easily prepared using the HTC of carbohydrates in the presence of latex nanoparticles and amphiphilic block-copolymers (Figure 1a). In addition we can also use the HTC of carbohydrates and phloroglucionol alone (Figure 1b) or in combination with High Internal Phase Emulsion (HIPE) as a soft-template (Figure 1c). Finally we can also produce well defined carbon monoliths using the HTC process of carbohydrates in the presence of gelating proteins (i.e. albumin, gelatine) acting as templates/scaffolds. (Figure 1d).

We will present details on the synthesis, characterization and some of the applications of these novel functional carbon materials.

References:

  1. M. M. Titirici, R. J. White, C. Falco, M. Sevilla, Energy Environ. Sci, 2012,5, 6796


22
High Quality Graphene Coatings on Metal Surfaces
Louis Nilsson, Mie Andersen, Richard Balog, Bjørk Hammer, Liv Hornekær, et al.
Department of Physics and Astronomy and Interdisciplinary Nanoscience Center iNANO, Aarhus University, DK-8000 Aarhus C, Denmark

A vast amount of research investigating the electronic properties of graphene has been published. Much less, however, has been published about graphene as a protective coating. We have investigated the effectiveness of a graphene coating on Pt(100) [1]in protecting the Pt surface against various gasses, such as CO, O2 [2], H2, H, H2S and combinations thereof, as well as towards atmospheric conditions. We find, by scanning tunneling microscopy and temperature programmed desorption spectroscopy, that the graphene is an efficient anti-corrosion coating for all tested gases at pressures below 10-6 mbar. At higher pressures CO was observed to intercalate under the graphene sheet. The same phenomenon was not observed for any of the other gasses investigated.

Atomic hydrogen (generated by cracking H2 in a tungsten capillary at 2000K) was found to bind to the grapheme coating, inducing a local shift in the hybridization of carbon atoms, from sp2 to sp3. The basal plane of the graphene remains intact during the exposure to atomic hydrogen and the hydrogenation is completely reversible upon annealing the sample to 1000 K. No change of the coating effect was observed for a low coverage of hydrogen atoms on the graphene sheet. At higher coverage, however, a stronger binding between the graphene sheet and the platinum substrate was observed. These findings are supported by our DFT calculations of the system.

1. Nilsson, L., et al., Preservation of the Pt(100) surface reconstruction after growth of a continuous layer of graphene. Surface Science, 2012. 606(3-4): p. 464-469.

2. Alpichshev, Z., et al., STM Imaging of Electronic Waves on the Surface of Bi(2)Te(3): Topologically Protected Surface States and Hexagonal Warping Effects. Physical Review Letters, 2010. 104(1).



23
Thermal conductive behavior of silicon carbide fiber /phenolic resin composites by the introduction of graphene nanoplatelets
kwangyoun cho, taeeon kim, kyungja kim
korea institute of ceramic engineering and technology

Silicon carbide (SiC) represents many unique properties, such as high strength, corrosion resistance, high thermal conductivity and high temperature stability. In recent years, the SiC fibers have been widely studied for use as a fillers in polymer-matrix composite (PMC) materials due to these characteristics. In order to improve the properties of such PMC materials dramatically, the use of graphene as an additive has been investigated both academically and industrially, as it can induce synergetic effect in the PMC materials, including thermoplastic and thermoset composite. In this study, we fabricated highly thermally conductive composites using Tyranno®-SA3 SiC fibers and a phenolic resin. Graphene nanoplatelets were added to composites to improve their thermal conduction properties. Thermal conductivity measurements indicated that in the case of the graphene-free composites, thermal conductivity was the highest (4.1 W/m∙K)



26
Preparation and Characterization of Porous Carbon from Date Palm Pits: Process optimization Using RSM
Suresh Reddy, et al.
The Petroleum Institute

The potential of Date palm pits to be a suitable precursor for preparation of porous carbon has been explored in the present work, utilizing phosphoric acid as the activating agent. The experimental methods reported in literature were chosen with certain modification in order to simplify the process. The process optimization was performed using the popular Response Surface Methodology (RSM) adopting a Box-Benkhen design. Process optimization was performed to maximize the activated carbon (AC) yield and the methylene blue (MB) adsorption capacity, with the process variables being the activation temperature, Impregnation ratio (IR) and the activation time. The textural characteristics were assessed based on nitrogen adsorption isotherms, SEM, FT-IR, while the adsorption capacity was estimated using the methylene blue (MB) adsorption. The optimized experimental conditions were identified to be an activation temperature of 400oC, Impregnation ratio (IR) of 3 and activation time of 58 min, with the resultant AC having yield of 44% and MB adsorption capacity of 345 mg/g. The textural characteristics of the AC reveal the BET surface area to be 725 m2/g, with pore volume of 1.26 cc/g, an average pore diameter of 2.91 nm and total micropore volume to be 0.391 cc/g. The low activation temperature, activation time with highest of yield renders the process technically/economically attractive for commercial manufacture.



27
Special designed charcoal for an environmental friendly heavy metal recycling
Gernot Rösler, Jürgen Antrekowitsch
University of Leoben

Due to the increase of global greenhouse gases caused partially by the metallurgical industry, this branch is looking for an alternative way to lower the harmful emissions by using renewable resources. One possibility which is described in the present paper is to substitute the commercial used solid fossil carbons for reduction like petroleum coke by biomass. Thereby it is very reasonable to use biomass wastes from the agricultural and forestry industry to decrease the costs and enable an economic concept. The main costs result from the fact, that generally it is not possible to utilize biomass –as delivered- in a metallurgical furnace because of the high reactive amount of volatile matter and water. Therefore these components have to be removed by a so called carbonization process. In this conjunction the chair of Nonferrous Metallurgy at the University of Leoben, Austria, together with the company BEFESA installed a special continuous carbonization unit in advanced lab scale to treat biomass cuttings at untypical high temperatures to get a suitable charcoal for the metallurgical industry.

This special developed charcoal is subsequently characterized concerning its chemical composition, reactivity as well as specific surface area to find the most suitable carbon carrier which allows the substitution of the fossil carbons in the above mentioned industry sector. A big variety of different experiments were carried out in various metallurgical pilot plants for the recycling of heavy metal containing residues. Based on the very successful results of these investigations, the possibility of the substitution of petroleum coke in one of the analysed processes, the foundry industry for cast iron, should be verified.

Typically the carbonization process takes place in an induction furnace where steel scrap is charged and thereby recycled. To convert the charged material into cast iron, where among others, also a carbon carrier has to be alloyed to form the correct solidification morphology. As already stated above the common carbonization agent is petroleum coke, which should be substituted by using charcoal originated by biomass from the agricultural and forestry industry. First preliminary tests carried out in a small scale induction furnace were very promising. Subsequently different charcoals will be investigated to have a closer look on the influence of the different substances in the charcoal to achieve a good carbonization result for a CO2 friendly production of cast iron. The results of the different trials are presented in this paper as well as some economical considerations.



28
Preparation of porous carbon from Date Palm Pits and Methylene blue Adsorption studies
C Srinivasakannan, et al.
The Petroleum Institute
The present study focuses on the process optimization of porous carbon preparation from date seed pits. The Response Surface Methodology (RSM) technique with Box-Behnken Method (BBM) was utilized with the response variables being the yield and BET surface area. The influencing parameters selected were activation temperature, Impregnation ratio (IR), and activation time. The optimum conditions were identified to be an activation temperature of 500 ⁰C, IR of 2 and activation time of 75 min with the resulting yield and BET surface area being 46 % and 838 m2/g. The average pore volume and average pore diameter was 1.07 cc/g and 1.69 nm respectively. In order to assess the suitability of the carbon for adsorption of macromolecules, methylene blue (MB) adsorption studies were assessed by varying the initial concentration and the adsorption temperature.


29
Synthetic Growth Concept: an algorithmic method for designing the structure and properties of nano-structured materials and low-dimensional phases
Gueorgui K. Gueorguiev
Department of Physics, Chemistry, and Biology – IFM, Linköping University, Sweden

Inherently nanostructured materials such as nanocomposites, cluster-assembled materials, etc., find a rapidly expanding role in materials science, nano-opto-electro-mechanical systems and solid state electronics. Often, the knowledge of the precise atomic arrangement (e.g., bonding, structural patterns) in such materials is insufficient. Predictive simulations are an appropriate tool to address structural issues in existing nanostructured materials and to suggest prospective novel compounds. In order to be able to address these problems by means of a standardized, algorithmic and transferable to wide range of inherently nanostructured materials, we devolved the Synthetic Growth Concept (SGC) based on the Density Functional Theory. SCG is understood as structural evolution by sequential steps of atomic rearrangement where each step is assigned according to the previous relaxed states. The precursor and/or building blocks for nanostructured compounds are described quantitatively together with their packing rules when they form condensed phases. By SGC we also address the interplay between bonding at surfaces/interfaces and the properties of the compounds.

One of the main directions of successful application of SGC is literally the tool behind a building up a new class of carbon-based materials: Fullerene-Like (FL) C:N:P:S::F … solids: 1) FL-CNx is one of the most prospective currently synthesizable CNx compounds. It is the industrially applied under the trade name of “rubber diamond” exhibiting outstanding mechanical properties. By using SGC, the FL-CNx structure evolution was successfully described and better understood [1]; 2) By employing SGC, we predicted FL Phospho-carbide (FL-CPx) [2], and successfully guided its deposition by magnetron sputtering. FL-CPx characterization by variety of techniques confirmed the SGC predictions for remarkable mechanical properties of FL-CPx (hardness, elasticity, etc.) [3]; 3) Fullerene-like Sulpho-Carbide (FL-CSx) [4] exhibits intermediate structural and mechanical properties in comparison with FL-CNx and FL-CPx and is a prospective alternative in terms of applications to both of them; 4) Recently, the solid Carbon Fluoride (CFx) by making use of the SGC was predicted and synthesized at Linköping University [5]. We studied the mechanisms of F incorporation in CFx thin films in their richness of structural patterns thus revealing a new compound with tunable structure (FL, polymeric, or amorphous) achieved by varying its F incorporation rate. The polymeric CFx is especially attractive since it may lead to a new material as significant as Teflon.

We have successfully applied the SGC also to low-dimensional C-based systems. The fluorination of the corannulene molecule - a prototypical template between the small Poly-Aromatic Hydrocarbons - has been studied in the context of the prospects to tune the properties of synthesizable C-based nano-units (e.g., clusters, molecules) achieved by controlling the degree of fluorination [6].

[1] G.K. Gueorguiev et al, Chem. Phys. Lett. 410 (2005) 228

[2] G.K. Gueorguiev et al, Chem. Phys. Lett. 426 (2006) 374

[3] A. Furlan et al, phys. stat. sol. (RRL) 2 (2008) 191

[4] C. Goyenola et al, J. Phys. Chem. C 116 (2012) 21124

[5] G. K Gueorguiev et al, Chem. Phys. Lett. 516 (2011) 62

[6] R. B. dos Santos et al, J. Phys. Chem. A 116, (2012), 9080



31
Polymer Carbon Sieves and Graphitized Polymer Carbons for Chromatographic and Sample Preparation Processes
William Betz, Michael Keeler, Jay Jones, Wendy Roe
Supelco

Spherical, high purity graphitized polymer carbons (GPC) and spherical, high purity carbon molecular sieves (CMS) have been synthesized for use in chromatographic and sample preparation processes. The use of carbons in gas and liquid chromatography has been realized for several decades, however the use of spherical GPC particles in packed bed and porous layer open tubular (PLOT) columns denotes a recent advancement in this technology.

New GPC and CMS particles have been synthesized which possess a wide range of textural properties and surface chemistries. For example, a 50um monodispersed GPC possessing a surface of 100m2/g has been effective in improving the adsorption and flow characteristics of a solid phase extraction (SPE) device for pesticide, insecticide and herbicide analyses. A second example is a family of these carbons, with surface areas ranging from one to two hundred meters per gram. GPC particles with sub-10um particle sizes have also been bonded to glass, metal and plastic substrates using patented, proprietary adhesives.

New spherical CMS particles have been synthesized for both gas chromatography (GC) and SPE analyses. For example, a CMS with a large microporous regime allowed for the preparation of coated surfaces for the extraction and subsequent analyses of small molecular sized, airborne contaminants. These applications focused also on a range of analytes from light gases to the semi-volatiles in aqueous environments. The surface chemistries of several 600um CMS particles have also been studied and applied to bulk extraction processes. CMS particles with sub-10um particle sizes have been bonded to glass, metal and plastic substrates using patented, proprietary adhesives.

Nitrogen porosimetry, helium pycnometry, particle size analyses, scanning electron microscopy and autotitration techniques were used to study the carbons. Adsorbent capacities and reversible adsorption characteristics have been determined using the respective sample preparation processes.



33
Towards large scale chemical synthesis of graphene ribbons
Mohammad Choucaira,*, John Strideb, Bin Gongb
a The University of Sydney
b The University of New South Wales

Versatile and feasible bulk production methods of graphene ribbons will be required to eventuate any kind of sustainable technology that can cater to an overwhelming market demand for high-end devices. Synthesis pathways to graphene ribbons are emerging, with both promising top-down and bottom-up approaches. Here we demonstrate the gram-scale synthesis of graphene ribbons by a bottom-up chemical approach. The process involves a single-step closed system reaction, in which the products are separated from a secondary structure containing bundled and free graphene ribbons. Atomic force microscopy (AFM) was used to measure the step heights between the surface of the ribbons and the substrate and was consistently found to be 4 Å ± 1 Å, proving them to be only a single atom thick. The graphene ribbons also have a tendency to stack forming a few layers. AFM indicated that the ribbons were generally 15-20 nn nm in width and scanning electron microscopy showed the ribbons were micrometres in length. Single area electron diffraction confirmed the hexagonal lattice of graphene and that the material was polycrystalline.



36
Porocarb - tunable porous carbons for energy applications
Christian Neumann, Joerg Becker, Sascha Pihan, Matthias Otter
Heraeus Quarzglas GmbH & Co. KG

Modern electrochemical systems pose new requirements to carbon materials regarding electrical connectivity and mechanical stability.

Here, we developed porous carbon particles with a high porosity and a unique hierarchical pore structure ranging from 10 to 1000 nms by hard templating technique. For the first time, materials of this type can be produced on a commercial scale.

The talk will give a short overview of standard carbons and their use in Li batteries. We show that there is a need for porous carbons in actual and future energy storage applications. We present available material grades with different porosities and pore structures and show that that the material can be optimally tailored for each application. We discuss the electrochemical behaviour of the materials used as an anode in a Li battery. Finally, we compare all important features of our material with commercially available porous carbons for energy applications.



37
Activation energy distribution of oxygenated surface complexes desorbed from a carbon surface oxidised at high pressures
Francisco Jimenez, Diana Lopez, Fanor Mondragón
Universidad de Antioquia

The modern coal combustion processes rely in the use of high pressure to achieve environmental regulations and acceptable thermal efficiencies. The experimental study of the effects of pressure in the heterogeneous reactions of oxygen with a carbonaceous surface is fundamental for the understanding of the coal combustion reaction. However, the experimental information on pressurized coal combustion is scarce.

The combustion of a coal particle is a heterogeneous process where the reaction stage is mediated by an oxygenated surface complex which after desorption form the combustion products, CO and CO2. The desorption of the surface complex will limit the reaction rate of the combustion reaction. The aim of this work was to evaluate the distribution of activation energies from the desorption of partially oxidised samples at different pressures.

Samples of Unicarb® (formerly known as Spherocarb) were oxidised with synthetic air at 500°C and pressure from 1 to 20 atm. The material conversion was kept within 2% and the products of the combustion during the partial oxidation of the carbonaceous surface were followed by Gas-FTIR. The oxidised samples were then desorbed in a controlled temperature program at 20°C/min up to 1000°C. The desorption products, CO and CO2, were analysed by Gas-FTIR, providing the temperature programmed desorption profiles (TPD) of the samples oxidised at different pressures. The TPD profiles were fitted to a distribution of energies of activation which show that the desorption of the oxygenated surface complexes exhibit a wide range of activation energies, from 200 to 400 kJ/mol, for all pressures of oxidation. The integration of the TPD profile showed that the increase of pressure does not affect the range of energies of activation but increases the population of oxygenated complexes on the carbonaceous surface. The kinetic data derived from the TPD profiles offers kinetic parameters relevant for the incorporation of pressure effects in the mechanisms of the heterogeneous combustion of carbonaceous surfaces.



39
Nanocrystalline carbon-TiO2 hybrid hollow spheres as possible electrodes for solar cells
Juan Matosa,*, Pedro Atienzarb, Hermenegildo Garcíab, Juan Carlos Hernández-Garridoc
a IVIC
b ITQ-UPV
c Unversidad de Cádiz

In this work we show a simple procedure for the preparation of carbon-TiO2 hybrid spheres [1] consisting on adding a suitable organic precursor during the solvothermal synthesis of TiO2. Nanocrystalline C-doped TiO2 hybrid hollow spheres were prepared by controlling calcinations of mixtures of furfural, chitosan or saccharose with titanium isopropoxide. The origin of the carbon influences the texture, the crystalline framework, and the optical and photoelectrochemistry properties of the TiO2. The success of the C-doping is manifested by the chemical stability of the hybrid hollow spheres and mainly by shift in the onset of the TiO2 absorption band and by visible light photoresponse of the resulting TiO2-C. Even after fully calcined and eliminate carbon doping, the spheres were able to absorb up to 12 times more photons from visible light in comparison of a commercial TiO2. Our procedure for C-doping TiO2 based solar cells indicate that C-TiO2 hybrid hollow spheres are potential precursors as film electrodes for solar cells and in the field of visible light photon induced catalysis.

[1] Matos J, Atienzar P, García H, Hernández-Garrido JC. Nanocrystalline carbon–TiO2 hybrid hollow spheres as possible electrodes for solar cells. Carbon (2012), http://dx.doi.org/10.1016/j.carbon.2012.10.044



40
Hydrogen Photoproduction under Visible Irradiation of Au-TiO2/Activated Carbon
Juan Matosa,*, Tiziana Marinob, Raffaele Molinarib, Hermenegildo Garciac
a IVIC
b University of Calabria
c ITQ-UPV

The photoproduction of hydrogen has been performed under visible light irradiation of Au-TiO2/activated carbon (AC) materials prepared by different activation methods [1]. Results were compared against those obtained under ultraviolet irradiation. Characterization of TiO2, AC and Au-TiO2/AC was performed by adsorption-desorption N2 isotherms, surface pH (pHPZC), infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectronic spectroscopy (XPS), diffuse reflectance UV-visible spectroscopy (DR/UV-vis), and transmission electron microscopy (TEM). The present results showed that functional groups on the carbon surface are responsible to enhance about 3 times the photocatalytic activity of Au nanoparticles deposited on TiO2. Characterization suggests that carboxylate anions detected on surface of some AC interact with metallic centre at TiO2 and this surface interaction would be responsible of the enhancement in the photoactivity. The present results suggest the possibility to study Au-TiO2 photocatalysts supported on basic AC on real solar conditions.

[1] Matos J, Marino T, Molinari R, Garcia H. Hydrogen photoproduction under visible irradiation of Au–TiO2/activated carbon. Appl Catal A: Gen 2011;417– 418:263–72.



41
Photocatalytic degradation of methylene blue under visible light on a suspended mixture of TiO2 and N-containing carbons
Juan Matosa,*, Magdalena Hofmanb, Robert Pietrzakb
a IVIC
b Adam Mickiewicz University

N-containing carbon materials were obtained from waste plum stones submitted to pyrolysis under Ar flow at 700oC or to activation under steam at 800ºC and enriched with nitrogen by heating in a NH3/air mixture at 270ºC or in NO at 300ºC. In situ mixtures of TiO2 and carbons were prepared by the slurry method and methylene blue photodegradation was chosen as a model reaction to verify the influence of N-containing carbons on the photocatalytic activity of TiO2 under artificial visible light irradiation [1]. From the kinetics of methylene blue degradation an important synergy effect between both solids was detected with a remarkable increase up to a factor of 5.3 higher in the photocatalytic activity on TiO2-C than that on TiO2 alone. This synergy effect suggests that nitrogen functional groups in carbon materials could play a photoassisting role to enhance the photoactivity of TiO2 under visible light irradiation. A mechanism for the production of surface N-based functionalities and the photoassisting role of N-containing carbons upon the photoactivity of TiO2 under visible light are discussed.

[1] Matos J, Hofman M, Pietrzak R. Synergy effect in the photocatalytic degradation of methylene blue on a suspended mixture of TiO2 and N-containing carbons. Carbon. Doi:10.1016/j.carbon.2012.12.002.



42
Selective phenol hydrogenation in aqueous phase on Pd-based catalysts supported on hybrid TiO2-Carbon materials
Juan Matosa,*, Avelino Cormab
a IVIC
b ITQ-UPV

TiO2-C materials have been prepared by solvothermal and slurry synthesis and the influence of carbon properties upon the catalytic activity and selectivity of Pd-based catalysts on phenol hydrogenation in aqueous phase under mild reaction conditions has been studied [1]. The nature of the catalysts can be easily modified to direct the reaction either to cyclohexanol (~100% yield) or to cyclohexanone (~96% yield). High selectivity to cyclohexanone is obtained with Pd on more polar TiO2-C supports, while when these are transformed into hydrophobic TiO2-C supports the resultant catalyst becomes selective to cyclohexanol. A mechanism explaining difference in selectivity is shown involving the inhibition of the cyclohexanone in presence of Lewis acid support (TiO2) or on hydrophilic carbon materials probably by a strong interaction of the cyclohexanone with the acid sites and because phenol is a strong H-bridge interacting system, and therefore it is enriched in the pores of the hydrophilic support, consequently, cyclohexanone is displaced (step 3) from the reactive surface. By contrast, less hydrophilic or hydrophobic surface clearly induces the hydrogenation of cyclohexanone to cyclohexanol. It can be concluded product distribution during the selective phenol hydrogenation in aqueous phase is easily controlled by controlling the functionalization of the hybrid support.

[1] Matos J, Corma A. Selective phenol hydrogenation in aqueous phase on Pd-based catalysts supported on hybrid TiO2-carbon materials. Appl Catal A: Gen 2011; 404:103–12.



47
Preparation and properties of carbon fibers coated with a TiC layer using a molten salt method
Zhijun Dong, Xuanke Li, Guanming Yuan, Zhenwei Cui, Ye Cong, et al.
The Hubei Province Key Laboratory of Coal Conversion & New Carbon Materials, Wuhan University of Science and Technology

Titanium carbide (TiC) coating were synthesised on Polyacrylonitrile (PAN)-based carbon fibers by a molten salt method using the molten salt mixture composed of LiCl, KCl and KF as a reaction medium. The surface morphology, tensile strength and oxidation resistance of the uncoated and TiC-coated carbon fibers were investigated. The wettability of these fibers by molten magnesium (Mg) and aluminum (Al) was also examined. TiC coatings obtained have a thickness of approximately 0.05-0.6 μm and are found to be uniform and adherent to the fibres. After being coated with a uniform and continuous TiC layer, the tensile strength of the carbon fibers decreases and their oxidation resistance is improved significantly. An increase in the TiC coating thickness leads to the reduction in the tensile strength of the carbon fibers and the improvement of their oxidation resistance. The oxidation activation energy of the carbon fibers increases from 127 to 170 kJ/mol after being coated with a 124 nm thick layer of TiC. Coating of carbon fibers with TiC also induces an increase in the total surface free energy of the carbon fibers, and as a result the wettability of carbon fibers with molten Mg and Al is improved remarkably.



48
Evaluation of iso-anisotropic portions of petroleum pitches by XRD, OM and MALDI-TOF.
Fabio Franceschi, Maria Helena Pereira, Letícia Paixão, Luiz Depine Castro
Núcleo de Competência Desenv Tec Carbono (NCDTC)

The perfect and complete identification of the components of iso/anisotropic portions of a petroleum pitch is still a challenge. The fully understanding about the chemical and physical reactions which occur during the heat treatment is vital. It is well established that the use of higher residential times leads to higher anisotropic contents. Hot centrifugation is one of the best methods to measure the anisotropic content in petroleum pitches and optical microscopy with polarized light is traditionally used to characterize this anisotropic portion. In this work the iso/anisotropic portions, obtained by hot centrifugation, of a group of petroleum pitches, produced by different residential times, are characterized by optical microscopy, X-ray diffraction and MALDI-TOF-MS. The aim is to establish correlations between the iso/anisotropic portions regarding their structures and molecular components and compare the X-ray diffraction patterns obtained for each petroleum pitch and respective centrifuged portions.



50
Ultra-short carbon nanotubes as novel near-infrared nanolabels
Christèle JAILLETa,*, Romain FAESa, Philippe POULINa, Laurent COGNETb, Laura OUDJEDIb, et al.
a Centre de Recherche Paul Pascal, CNRS UPR 8641, 115 Avenue Schweitzer, 33600 Pessac, FRANCE
b Laboratoire Photonique Numérique et Nanoscience, Université de Bordeaux, 351 Cours de la Libération, 33405 Talence, FRANCE

Ideal optical tracers for imaging in biological tissues must be nanosized, biocompatible and photo- or thermally active, via photoluminescence or absorption, in Near-InfraRed (NIR) wavelengths. Ultra-short carbon nanotubes (CNTs) would offer a unique opportunity to combine these properties and become thereby a novel type of highly efficient biolabels. We develop in this work ultra-short CNTs and their bio-functionalization, for a use as NIR nanomarkers. We target in particular the achievement of single-wall carbon nanotubes shorter than 10 nm that can be visualized by photothermal spectroscopy[1] or photoluminescence.

To achieve our goal we have decide to develop a simple scission procedure based on chemical oxidizing treatments[3] and/or tip-sonication[2]. After the scission process a Density Gradient Ultracentrifugation (DGU)[4] step of the CNTs dispersion has been performed for sorting tubes by length. The different fractions collected after DGU (from top to bottom of the centrifuge tube) have been characterized by Raman Spectroscopy, Atomic Force Microscopy (AFM) and UV-Vis-IR spectroscopy. For example, with UV-Vis-IR measurements a blue shift of the absorption peaks is observed for the shortest nanotubes which is in good agreement with theoretical expectations. In a more general way the analysis results show that it is possible to sort the tubes according to their lengths and to get ultra-short tubes, as desired.

Currently, we try to optimize the short tubes yield and different routes are tested to bio-functionalize the carbon nanotubes: a covalent functionalization for photothermic spectroscopy, and a non-covalent functionalization to attempt to preserve the CNTs luminescence properties. Soon the first biological tests will be performed by the Interdisciplinary Institute for NeuroScience at Bordeaux to study the dynamics of glutamate receptors on neurons in culture and in brain slices.

[1] S. Berciaud et al., Nano Lett., 7 (2007), pp. 1203-1207.

[2] A. Lucas et al., J. Phys. Chem. C, 113 (2009), pp. 20599-20605.

[3] B. K. Price et al., Chem. Mater., 21 (2009), pp. 3917-3923.

[4] X. Sun et al., JACS, 130 (2008), pp. 6551-6555.



51
ACTIVATED AND MODIFIED CARBON WITH CALCIUM FOR THE ADSORPTION OF MULTICOMPONENT SOLUTIONS OF AB25, Zn2+ AND Cd2+.
Rigoberto Tovar, Ma. Del Rosario Moreno, Virginia Hernández, Adrián Bonilla
Instituto Tecnológico de Aguascalientes

This work reports the antagonic and synergic adsorption processes involved in the multicomponent removal of heavy metals (Cd2+, Zn2+) and dye acid blue 25 (AB25) using an activated carbon modified with egg shell wastes. Adsorption experiments were performed in ternary system: AB25-Zn2+-Cd2+ where Taguchi experimental design has been used to analyze the adsorbent performance and to identify the adsorption processes caused by the simultaneous presence of these pollutants. Specifically, a statistical analysis based on the signal-to-noise (S/N) ratio and the multicomponent adsorption capacities has been used to characterize the adsorbent performance and its dependence on the operating conditions for the multicomponent adsorption of heavy metals and dye using activated carbon. Results indicated that this system may show both competitive and synergic adsorption processes. Dye AB25 enhances the removal of heavy metals and reduces the competitive adsorption between the metal ions present in multicomponent solution especially for Cd2+. This synergic adsorption depends on the concentrations of heavy metals and dye, and the improvement of metal adsorption is also dependent on the metal ion. This improved adsorption process appears to be mainly caused by an ion exchange mechanism that involves the functional group –SO3- of dye molecule and the heavy metals. Multicomponent isotherm models and an empirical model obtained from response surface methodology have been used and compared in the modeling of multicomponent adsorption data. This study provides new findings on the multicomponent adsorption of dyes and heavy metals using activated carbons.



52
The intrinsic property of activated carbon fibers to act as redox mediators in the transformation of nitroaromatic compounds to their amino derivatives
Hector Javier Amezquita-Garcia, Elias Razo-Flores, Francisco Cervantes, Jose Rene Rangel-Mendez
Instituto Potosino de Investigación Científica y Tecnológica

Activated Carbon Fibers (ACFs) have unique characteristics compared with granular or powder activated carbons that makes them suitable for their use as catalyst in the transformation of recalcitrant pollutants. Among them include high superficial area exposed to pollutants, presence of surface functional groups with redox properties (quinonoid complexes) and ease in handling when used in felt or fabric forms. This study explores the use of ACFs as redox mediators in the anaerobic reduction of two model nitroaromatic compounds: 4-nitrophenol and 3-chloronitrobenzene. The effect of ACF chemical properties on the reduction of nitroaromatic compounds was measured by chemical oxidation of ACFs with nitric acid and thermal treatment at 700°C under an inert atmosphere, before their use in batch experiments. The results show that ACFs in basal medium are necessary to transform the nitroaromatic compounds to their corresponding aminoaromatic, indicating the function of ACF as redox mediators.



56
Photoelectrochemical response of carbon-semiconductor thin films applied to heterogeneous photocatalysis
Marta Haro, Leticia F. Velasco, Conchi O. Ania
Instituto Nacional del Carbón (INCAR, CSIC), Oviedo 33080, Spain

The use of light energy is particularly useful for the degradation of refractory pollutants, since the excitation of electronic molecular states at energies provided by light may induce chemical bond breaking. Consequently, heterogeneous photocatalysis based on semiconductors is becoming one of the most promising green chemistry technologies in the environmental remediation arena. However major cornerstones of photocatalytic processes that prevent their large scale implementation are related to the photoelectrochemical properties of the semiconductor (low visible light activity, high recombination of photogenerated species, etc.). Coupling carbon materials as additives to semiconductor has long proved to be an attractive strategy to improve the photocatalytic efficiency of carbon/semiconductor composites on the photodegradation of a variety of recalcitrant pollutants, albeit the exact role of the carbon phase on the enhanced performance of the composites has not yet been fully understood [1-3].

Aiming at understanding the mechanisms of the photoinduced processes occurring in such hybrid photocatalysts, we have investigated the photoelectrochemical response of carbon/titania thin film electrodes under UV light, and their efficiency for the photo-oxidation of phenol. In a first step, spectrometric techniques have been applied to investigate the structural and optical properties of the carbon/semiconductor composites compared to the intrinsic characteristics of the unsupported semiconductor. The second approach consisted in the preparation of thin film electrodes to explore the photoinduced reactions occurring at the interface under UV light and bias potential. The gathered results provided experimental evidence on the carbon-mediated photoinduced reactions, distinguishing different mechanisms: i) the carbon matrix acts as a charge trapping network that modifies the fate of the photogenerated charge carriers (avoiding recombination and thus enhancing the photocatalytic efficiency); ii) illumination of the carbon additive renders photogenerated carriers due to p-p* transitions, capable of participating in charge transfer reactions with electron donors present in the reaction medium. Our results point out that beyond the beneficial effect of the porosity of the support, the carbon matrix does play an important role in the photo-induced reactions of carbon-supported photocatalysts.

References

[1] R. Leary, A. Westwood, Carbonaceous nanomaterials for the enhancement of TiO2 photocatalysis, Carbon 49, 2011, 741-72.

[2] L.F. Velasco, J.B. Parra, C.O. Ania, Role of activated carbon features on the photocatalytic degradation of phenol, Appl Surface Sci., 256, 2010, 5254–5258.

[3] L.F. Velasco, I. M. Fonseca, J. B. Parra, J.C. Lima, C.O. Ania, Photochemical behaviour of activated carbons under UV irradiation, Carbon 50, 2012, 249-258.

[4] M. Haro, L.F. Velasco, C.O. Ania, Carbon mediated photoinduced reactions as a key factor in the photocatalytic performance of C/TiO2, Catal. Sci Technol. 2, 2012, 2264-2272.



57
PREPARATION OF ACTIVE CARBON WITH DIFFERENT SHAPE OF PARTICLES AND CHARACTERISATION OF THEIR PROPERTIES
Bronislaw Buczek
AGH University of Science & Technology
Steam activation process developed the porous structure of cylinder and ring shape coal-chars. Micropore and mesopore structure of active carbon with various burn-off was evaluated using nitrogen adsorption/desorption isotherms. Parameters of the Dubinin-Radushkevich equation were calculated as well as the micropore size distribution by the Horvath-Kawazoe method. The results of textural investigations showed that more uniform micropore structure and better mechanical properties were obtained for activated ring particles.It means that molecular-sieve properties occur in active carbons prepared in this way and shows that the reaction proceeds close to the kinetic region. Owing to the different shape, flow resistance through the bed of ring-shaped particles is lower than that for the bed of cylindrical particles.


59
Performance of activated carbons on consecutive photocatalytic cycles
Leticia F. Velascoa,*, Rocío J. Carmonaa, Juan Matosb, Conchi O. Aniaa
a Instituto Nacional del Carbón (INCAR, CSIC), Oviedo 33080, Spain
b Department of Catalysis and Alternative Energies. Venezuelan Institute for Scientific Research (IVIC), 20632, Caracas 1020-A, Venezuela

In environmental chemistry, photochemical reactions are extremely useful for the degradation of refractory pollutants, since the excitation of electronic molecular states at energies provided by light may induce chemical bond breaking [1]. However, the large-scale implementation of photocatalytic processes is yet nowadays hindered by technological and economical drawbacks (low semiconductor activity under visible light, high recombination rate of photogenerated electron–hole pairs, recovery and reutilization issues).

Among different approaches to overcome these challenges, heterogeneous photocatalysis based on carbon materials as catalysts and supports has become one of the most promising approaches [2,3]. Particularly, previous studies have demonstrated the self-photochemical activity of certain activated carbons under irradiation in the absence of conventional semiconductors and their ability to generate radical species [4,5]. Despite the increasing interest in the topic, neither the exact role of carbon in the photochemical behavior of carbon photocatalysts or carbon/semiconductor composites, nor the mechanisms occurring at the carbon/semiconductor interfaces, have yet been clarified; and most plausible hypotheses remain yet rather speculative. However, beyond the photochemical behavior showed by some of these carbon materials, it is still necessary to corroborate their catalytic activity through the performance of consecutive photodegradation runs.

The objective of this work was to explore the potential application of porous carbons showing photochemical activity in wastewater remediation; for this, we have investigated photocatalytic degradation of phenol from solution after several consecutives runs. The performance of the carbons was compared to that obtained for titania powders under similar experimental conditions. The photoefficiency of the systems was evaluated in terms of phenol conversion and mineralization degree upon consecutive cycles; additionally, the evolution of the main phenol photodegradation intermediates was also evaluated upon cycling. The gathered results were also correlated to the chemical, textural and structural changes detected on the activated carbons during the irradiation cycles, paying special attention to the role played by the surface chemistry of the carbon catalysts.

References

[1] N. Serpone, E. Pelizzetti (Eds) in Photocatalysis: fundamental and applications, ed. E. Pelizzetti and N. Serpone, Wiley-Interscience, New York, 1989.

[2] R. Leary, A. Westwood, Carbonaceous nanomaterials for the enhancement of TiO2 photocatalysis, Carbon 49, 2011, 741-72.

[3] J. Matos, J. Laine, J.-M. Herrmann, Synergy effect in the photocatalytic degradation of phenol on a suspended mixture of titania and activated carbon. Appl. Catal. B 18, 1998, 281-91.

[4] L.F. Velasco, J.B. Parra, C.O. Ania, Role of activated carbon features on the photocatalytic degradation of phenol, Applied Surface Science 256, 2010, 5254-5258

[5] L.F. Velasco, I.M. Fonseca, J.B. Parra, J.C. Lima, C.O. Ania, Photochemical behaviour of activated carbons under UV irradiation, Carbon 50, 2012, 249-58.



60
Grafting of Nitrophenyl Groups on Multi-Walled Carbon Nanotube Surface
Anca Dumitru, Keith Scott
School of Chemical Engineering and Advanced Materials, Newcastle University, UK

The applications of carbon nanotube modification are correlated with the ability to control the interfacial properties of carbon, especially surface chemistry and reactivity. Surface modifications with nitrophenyl moieties were found to have significant effects on particle properties as well as electrochemical behaviors.

Chemically modification of multi-wall carbon surfaces by the reduction of diazonium salts (4-nitroaniline and 4-Nitrobenzenediazonium tetrafluoroborate) is described. The nitrophenyl functionalized multi-walled carbon nanotubes have been characterized by X-ray photoelectron spectroscopy (XPS) and electrochemical analysis. XPS measurements at the N1s core level show two components at 406 and 400 eV. The main component at 406 eV is due to the nitro functionalities and confirms that 4-nitrophenyl groups were not degraded during the grafting step.

The electrochemical behavior of a 4-nitrophenyl modified carbon nanotubes have been investigated in aqueous acidic, alkaline and phosphate buffer (pH 7) media. Nitrophenyl modified carbon materials have characteristic electrochemical signature of the nitro group. In the first reduction sweep of the samples modified with 4-nitroaniline, well-defined voltammetric wave corresponding to the irreversible four electron, four proton reduction four proton reduction of the nitro group (−NO2) to a hydroxylamine (−N(H)OH) is observed at −0.33 V in acidic media, at -0.8 V in alkaline media and -0.7 V in phosphate buffer solution (versus Ag/AgCl). For the samples modified with 4-Nitrobenzenediazonium tetrafluoroborate, the irreversible wave is not so well-defined in acid media andappears at more negative potential −0.46 V, at -1V in alkaline media and -0.77 V in phosphate buffer solution (versus Ag/AgCl).



62
Effect of confined space reduction of graphite oxide followed by sulfur doping on oxygen reduction reaction in neutral electrolyte
Mykola Seredycha,*, Teresa Bandoszb
a CCNY
b CCNY/CUNY

In this paper we show a high activity for ORR with the high selectivity of this process/tolerance to the presence of fuel of graphite oxide reduced in confined space of silica matrix and its S-doped counterpart. A paramount importance here is the presence of sulfur in C-S aromatic structures which results result in a positive charge as active sites. Moreover, that positively charged surface can attract not only O2 but also OH- ions from water splitting and therefore the protons can be used in oxygen reduction reactions in a neutral electrolyte. As shown, the RGOS exhibits also some volume of very small pores, which can further enhance this process. Its partially graphitic nature can facilitate charge transfer, and the transfer of active species to reaction sites is enhanced by the specific porosity being the replica of the template silica mesopores. The high hydrophobicity of the surface along with its positive charge play a role in attraction of O2 dissolved in water.



63
Pore space utilization in nanoporous carbon-based supercapacitors: Effects of conductivity and pore accessibility
Mykola Seredycha, Teresa Bandoszb,*
a CCNY
b CCNY/CUNY

Composites of commercial graphene and nanoporous sodium-salt-polymer-derived carbons were prepared with 5 or 20 weight % graphene. The materials were characterized using the adsorption of nitrogen, SEM/EDX, thermal analysis, Raman spectroscopy and potentiometric titration. The samples’ conductivity was also measured. The performance of the carbon composites in energy storage was linked to their porosity and electronic conductivity. The small pores (< 0.7) were found as very active for double layer capacitance. It was demonstrated that when double layer capacitance is a predominant mechanism of charge storage, the degree of the pore space utilization for that storage can be increased by increasing the conductivity of the carbons. That degree of pore space utilization is defined as gravimetric capacitance per unit pore volume in pores smaller than 0.7 nm. Its magnitude is affected by conductivity of the carbon materials. The functional groups, besides pseudocapacitive contribution, alos increased the wettability and thus the degree of the pore space utilization. Graphene phase, owing to its conductivity, also took part in an insitu increase of the small pore accessibility and thus the capacitance of the composites via enhancing an electron transfer to small pores and thus imposing the reduction of groups blocking the pores for electrolyte ions .



64
New Discoveries for Carbon-Catalyzed NO Oxidation: Pore Size-Sensitive Activity and Surface-Dependent Kinetics
John Atkinsona, Zhanquan Zhangb, Zifeng Yanc, Mark Rooda,*
a University of Illinois
b China University of Petroleum, University of Illinois
c China University of Petroleum

Low temperature, carbon-catalyzed NO oxidation has maintained consistent research interest since its discovery in the early 1990s. Oxidation of NO, which comprises 90 – 95% of total nitrogen oxides (NOx) in combustion flue gas, followed by absorption of NO2 is an alternative abatement technology that removes the expenses (e.g., metal oxide or precious metal catalysts, gas reheating) associated with selective catalytic reduction as well as the potential for ammonia and N2O emissions. The role of carbon-catalyzed NO oxidation process parameters (e.g., temperature, gas space velocity, gas composition) on activity and kinetics has been thoroughly described. However, more thorough fundamental studies investigating the role of carbon’s intrinsic physical and chemical properties on the NO oxidation mechanisms are necessary for the development of catalysts tailored specifically for abating emissions of NOx. In this work, activated carbon materials are carefully selected and modified to elucidate the individual impacts of carbon’s physical and chemical properties on NO oxidation.

Carbons with different pore size distributions were treated to remove ash and oxygen, giving them similar chemical properties (e.g., elemental composition, surface charge) and varying physical properties. Catalytic NO oxidation was evaluated at 50 oC with a gas space velocity of 2.4 ×104 cm3·g-1·h-1 in a gas stream containing 10 vol.% O2, 400 ppmv NO, and balance N2. Results indicate that NO oxidation conversion efficiency is independent of the carbon’s total surface area or pore volume, for the conditions tested. Instead, the reaction depends on the pore size distribution of the catalyst, with peak activities obtained for pore widths between 0.5 and 0.7 nm. Larger or smaller pore widths exhibit reduced NO oxidation efficiency. Highest conversion efficiencies are obtained for catalysts with a large volume of the specified pore widths. Increasing the total pore volume without altering the number of pores in this range of widths causes little improvement in conversion efficiency.

Surface functionalities were then added to a single activated carbon fiber cloth (ACFC) to identify the preferred chemistry of physically similar NO oxidation catalysts. Surface oxygen groups are preferred functionalities because they inhibit surface oxidation of carbon by recently formed NO2. Occupying surface sites prevents this surface oxidation, allowing the reaction to stabilize more rapidly. Acidic oxygen functional groups, in particular, are shown to improve reaction kinetics without changing NO oxidation efficiency. After a 280% increase in the bulk oxygen content of ACFC, there is a corresponding 65% reduction in the time required to release NO2 from the carbon surface, allowing the reaction to achieve the same steady-state NO conversion efficiency 45% faster.

Overall, mechanistic studies show that carbon-catalyzed NO oxidation is composed of independent and consecutive steps: (1) rapid NO oxidation in micropores, and (2) NO2 adsorption/reaction with carbon. Step 1, which controls catalytic activity, depends on carbon’s physical properties while step 2, which controls reaction kinetics, depends on carbon’s surface chemistry. Such findings support the investigation of tailored carbon materials as well as non-carbon based materials (e.g., zeolites, MOFs) as NO oxidation catalysts.



65
Exploration of Synthetic Probe Molecules to Characterize Decolorizing Properties
Billy-Paul Holbrook
MeadWestvaco

The industry standard for evaluating decolorizing properties of activated carbon is determined by adsorption of food grade materials (i.e. molasses, caramel, etc.). The use of food grade materials has several drawbacks including short life span of standards, needed use of buffers, biological degradation over time (refrigeration is required), compound compositions are unknown and inconsistent from batch to batch and adsorbed molecules are largely unknown. From an industry view point, having a method that uses a more robust and uniform adsorbate would provide a more universal and consistent test method. The use of a synthetic and controlled adsorbate would reduce complexity of the experimental method (no buffer needed, refrigeration not required, little to no biological degradation, etc.) and would increase the consistency of the calculated decolorizing properties. Furthermore, the turnover time for running the test would be reduced due to increased longevity of the standards and less procedural steps by not requiring a buffer..

To examine alternate methods several synthetic probe molecules were chosen as adsorbates. Commercial grade activated carbons were adopted as the adsorbents. For creating a simpler method several parameters were placed on the synthetic adsorbate. These criteria include water solubility, similar chemical makeup to sugars and colorants in chemical makeup (-C-O-C- and -OH groups, etc.), and the molecular size could be varied. From this set of criteria polyethylene glycol (PEG) and cyclodextrin were chosen as the synthetic adsorbates. The cyclodextrin molecules examined were γ-cyclodextrin and α-cyclodextrin. Adsorption properties from the synthetic adsorbates, including adsorption capacity (Qe) and Freundlich Adsorption isotherm constants (K and n), were compared to the molasses decolorizing value of the respective activated carbon.



66
Facile synthesis of porous graphene nanosheets for supercapacitors
Lili Jiang, Jun Yan, Zhuangjun Fan, Tong Wei
Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China

We report the facile synthesis of porous graphene nanosheets (PGNs) using the etching of graphene sheets by MnO2. An electrode made from PGNs exhibits a specific capacitance of 154 F g-1 at 500 mV s-1 in 6 M KOH compared to a value of 67 F g-1 for graphene nanosheets, and a low capacitance loss of 12% after 5000 cycles. Interestingly, PGN electrode material shows an excellent rate capability due to its open layered and mesopore structures that facilitate the efficient access of electrolytes to the electrode material and shorten the ion diffusion pathway through the porous sheets. This approach offers the potential for cost-effective, environmentally friendly and large-scale production of PGNs.



67
Three-dimensional hybrid materials of fish scale-like polyaniline nanosheet arrays on graphene oxide for high-performance ultracapacitors
Xu Chena, Jun Yana, Zhuangjun Fana,*, Tong Weia, Guoqing Ningb
a Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China
b State Key Laboratory of Heavy Oil Processing, China University of Petroleum, Beijing, Changping 102249, China

Three-dimensional (3D) hybrid materials composed of 2D fish scale-like polyaniline (PANI) nanosheet arrays on graphene oxide sheets and carbon nanotubes were synthesized by a one-step process using a simplified template-free polymerization method. PANI nanosheet growth is proposed to be accomplished through electrostatic interaction, hydrogen bonding, and π-π stacking interaction. Such a material exhibits specific capacitances of 589 and 413 F g-1 at 0.2 and 5 A g-1, respectively, compared to pristine PANI of 397 and 180 F g-1. After 1000 cycles, the composite still retains 81% of its initial capacitance, while PANI retains only 48%.



68
High-performance supercapacitor electrodes based on highly corrugated graphene sheets
Xiaoliang Wu, Jun Yan, Zhuangjun Fan, Tong Wei
Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China

Highly corrugated graphene sheets (HCGS) have been prepared by a rapid, low cost and scalable approach through the thermal reduction of graphite oxide at 900 °C followed by rapid cooling using liquid nitrogen. The wrinkling of the graphene sheets can significantly prevent them from agglomerating and restacking with one another face to face and thus increase the electrolyte-accessible surface area. The maximum specific capacitance of 349 F g-1 at 2mV s-1 is obtained for the HCGS electrode in 6 M KOH aqueous solution. Additionally, the electrode shows excellent electrochemical stability along with an approximately 8.0% increase of the initial specific capacitance after 5000 cycle tests. These features make the present HCGS material a quite promising alternative for next generation of high-performance supercapacitors.



69
Template synthesis of pillared-porous 3D carbon nanoarchitectures: High-performance electrode materials for supercapacitors
Hongze An, Jun Yan, Zhuangjun Fan, Tong Wei
Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001, China

We are the first to present a 3D pillared-porous graphene (PPG) with pore wall pillars supporting in between the carbon layers obtained by the carbonization of pitch on the porous MgO template. The resulting PPG possess interconnected open-pore surfaces, self-supporting mesoporous and conductive network, high surface area, and high overall electrical conductivity. We have found that the unique structure endows the high-rate transportation of electrolyte ions and electrons throughout the electrode matrix, resulting in specific capacitance as high as 289 F g-1 at 2 mV s-1 (even 180 F g-1 at 1000 mV s-1), and good electrochemical stability (94% of the initial capacitance after 10000 cycles). Large-scale production of porous graphene by template-directed methods, which offers a new pathway for application in energy storage.



70
Preparation and electrical response of pillared carbon thin films from the reduction of silylated graphite oxide by UV light irradiation
Yoshiaki Matsuo, Tachibana Yuji
University of Hyogo

We have recently reported the preparation of pillared carbon thin films and their size selective electrical response to organic molecules [1]. However, the selectivity was not high enough. In order to imporve it, it is necessary to reduce the distance between pillars or interlayer spaicngs. In this study, pillared carbon thin films showing higher selective electrical response were prepared from the reduction of silylated graphite oxide with lower silicon contents. In order to avoid the removal of silicon containing species from the graphite oxide layers, silylated graphite oxide precuosors were reduced by UV light irradiation at lower temperatures below 100°C. The intercalation behaviors of oganic molecules into the resulting pillared carbon thin films and their electrical response during exposure to gaseous molecules were investigated.

The reduction of the thin films of graphite oxide silylated with octyltrichlorosilane was completed within 24h and the interlayer spacing decreased from 1.47 to 0.81 nm. The UV-Vis absorption peak reached 265 nm as the result of the removal of alkyl chains and oxygen containing functional groups. IR measurement of the films indicated that the irradiation of the light with higher energies was effective for the dissociation of Si-C bondings in the silylating reagents attached to the graphite oxide layers. These results strongly suggest that pillared carbon film was obtained. When the pillared carbon thin films were immersed in the solutions of organic molecules such as vinylene carbonate, diethoxyethane, propylene carbonate, the shift of X-ray diffraction peak of them was not observed, indicating that they can not penetrate into the interlayer gallery of the present pillared carbon. The electrical response of pillared carbon thin films was very small upon the exposure of them to organic vapors or ozone because they were adsorbed only on the surface of the pillared carbons. On the other hand, pillared carbon with a larger interlayer spacing was obtained from the thin film of graphite oxide silylated with octyltrichlorosilane and then with 3-aminopropyltriethoxysilane. A large electical response was observed only when the pillared carbon thin film was exposed to ozone gas. The distance between pillars for the entrance of the molecules became slightly larger than that in the pillared carbon obtained above but smaller than that in those reported in our previous paper [1].

Reference

[1] Y. Matsuo, Y. Tachibana, K. Konishi, Carbon, 50, 5340-5350 (2012).



71
On how the carbon surface chemistry and electrolyte pH may affect to the capacity of the EDLC
J. Angel Menéndez, Esther G. Calvo, Natalia Rey-Raap, José M. Bermudez, Ana Arenillas, et al.
Instituto Nacional del Carbon INCAR-CSIC, Apartado 73, 33080 Oviedo SPAIN

Electric double-layer capacitors (EDLCs) are electrochemical devices that store electrical energy by means of electrostatic phenomena, i.e. through the electric double layer formed between electrodes and electrolyte. Although this is the main charge storage mechanism of supercapacitors, redox reactions can also take place in the electrode surface increasing the total capacitance. It is commonly accepted that these redox processes are produced when the electrode material displays surface functional groups capable of being oxidized and/or reduced in the presence of the electrolyte. However, the pseudocapacitance is ultimately governed by the amount of positive and negative charges present on the carbons surface (that may constitute the electrodes of supercapacitors) and these charges are not only generated in the surface groups but also in the basal planes of carbons. On the other hand, the amount of positive and negative charges on the carbon surface (i.e. electrode) depends on both its point of zero charge (pHpzc) and the pH of the media (i.e. electrolyte). By definition when the pHpzc = medium pH, 50% of the charges on the electrode surface will be positive and 50% negative. Moreover, if the pHpzc > pH, the electrode surface will have an excess of positive charges and vice versa. Thus, both the surface chemistry of the carbon and the pH of the electrolyte influence these redox phenomena.

When a highly porous carbon xerogel was employed as electrode material for supercapacitors with aqueous electrolytes of different pH, it was found some evidence that the pseudocapacitance has a higher dependence on the amount of positive charges present on the carbon surface than anything else. Thus, when H2SO4 was used as electrolyte (i.e. pHpzc > pH), there is an excess of positive charges and a greater presence of redox reactions. On the contrary, with an electrolyte based on KOH (1M solution), a system based exclusively on the electrostatic energy storage was achieved, i.e., there was no evidences of pseudocapacitive effects. Despite these results, more research will be necessary to confirm this hypothesis.



73
INFLUENCE OF QUINOLINE-INSOLUBLE CONTENT, ANISOTROPY AND POROSITY ON MECHANICAL RESISTANCE OF AMORPHOUS CARBON PRODUCED FROM DIFFERENT PITCH BINDERS
Marcio Coutinhoa,*, Carlos Henrique Dutraa, Wladmir Souzab, Luiz Castroa
a Brazilian Army Technological Center
b Petrobras Cenpes

Different amorphous carbon artifacts, were prepared from non-conventional precursors, such as petroleum and coal tar pitches, binder content was kept constant at 23%, regular coke with a Currie granulometric distribution was used, quinolone-insoluble content was determined in accordance to ASTM D2318-08, on the other hand, mesophase content was evaluated through high temperature centrifugation technique, once optical microscopy is limited to samples with mesophase content up to 20%. Porosity plays a very important role, on physical properties of carbon based materials. Mercury Intrusion Porosimetry (MIP) was applied in order to characterize pore size distribution, from meso- to macropores found on the studied samples, on the pressure range from 2 up to 60000 psia, the produced artifacts, under mechanical point of view, exhibit fragile behavior, leading to a dependence of mechanical resistance values on existing structural failures. Results from compression resistance test, indicate that increasing porosity, compression resistance decreases on studied samples, which was already expected, once increasing void space within material, its mechanical resistance tends to decrease, this test was performed in accordance to ASTM C695. The variation on physical chemical properties from applied precursors suggests, a relevant effect on physical mechanical properties of amorphous carbon samples, especially, the influence of mesophase content on material´s porosity.



74
Characterization of Pitch Derived from Tar Oxidized in a Falling Film Reactor
Chong Chen
GrafTech International Holdings, Inc.

Oxidation treatment is a known technology used to convert tar to pitch or upgrade pitch by raising its softening point and carbon yield. In this paper, a novel approach to oxidize a tar by using a falling film reactor and the characterization of the product are presented. A tar with near zero carbon yield was upgraded to a pitch with a carbon yield of 19.5% by air oxidation in a falling film reactor with the reaction time as short as ~5min, which is several orders of magnitude reduction in reaction time compared to that carried out in a conventional air blowing reactor. The resultant pitch was characterized by FTIR, elemental analysis, TGA and solvent solubility, etc. The reaction mechanism is also discussed.



75
Gas-evolution investigations during thermal destruction of intercalated graphite
Natalia Maksimova, Makhsud Saidaminov, Viktor Avdeev
Moscow State University

Graphite-based low-dense carbon materials are widely used in the production of sealing materials and oil adsorbents. Traditional procedure technique of these materials consists of several steps. First step is expandable graphite obtaining included natural graphite intercalation by nitric or sulfuric acids and following hydrolysis. After that expandable graphite is subjected to momentary heat at 900-1000 oC that leads to formation of exfoliated graphite with bulk density of 2-5 g/l. There is much research on Bronsted acids intercalation into graphite. However destruction of expandable graphite by thermal shocking, in which many harmful gases evolves, is not still investigated. Our work is devoted to the study of this stage. New technique of gas determination in thermal destruction of expandable graphite produced from graphite nitrate II-IV stages has been offered. Its correctness was confirmed by thermogravimetry and infrared spectroscopy. Static and dynamic modes were chosen to thermal destruction of expandable graphite. Static mode was carried out in three types of atmospheres: oxidizing, inert and reducing. Systematic analysis of the gases evolved during the thermal decomposition of expandable graphite is presented. The composition of these gases was found to depend on initial graphite nitrate stage number and atmosphere in which it was expanded. Dynamic mode was realized in argon atmosphere. Two-steps of gas evolution with increase of temperature were registered in dynamic mode. The same two-steps effect was observed on thermogravimetry curves and infrared spectra. Dynamic mode allows determining of chemical reactions carrying out in thermal destruction.



76
Thermo-piezoresistive effect of a paper sensor based on Al/CNT nanocomposites
Marcos Reisa,*, Sónia Simõesb, Filomena Vianab, Manuel Vieirab, Jordan Del Neroa
a Federal University of Para
b University of Porto

Paper sensor based on Aluminum/Carbon Nanotubes (Al/CNT) nanocomposites were synthesized by an arc discharge technique under argon/acetone atmosphere and ultrasonically dispersed in distilled water to form an ink-like composite. Synthesis was performed by arc plasma on high pure graphite rod, filled by aluminum powder as anode and an aluminum plate as cathode under discharge conditions of 85 A and 20 V. Moreover, the ink was spread onto commercial paper to produce a conductive thick film. Experimental results show that the electrical resistance of Al/CNT nanocomposite on paper changes when a mechanical stress and/or heat is applied. The multisensory properties obtained are the following: piezoresistive effect, i.e. electrical resistance shows linear dependence with pressure intensity at room temperature; polynomial relationship between electrical resistance and temperature; and high accuracy thermal sensor compared to a K type thermocouple at 25 °C. The nanocomposite and paper morphology was analyzed by Scanning Electron Microscopy with Energy Dispersive Spectrometry (SEM/EDS) and Transmission Electron Microscopy (TEM) which a favorable surface for physisorption was observed. The results indicate that the paper sensor based on nanocomposite shows good performance as a thermo and piezoresistive sensor.



78
Functionalisation of carbon fiber toward enhanced fiber-matrix adhesion
Linden Servinisa,*, Luke C. Hendersona, Bronwyn L. Foxa, Thomas R. Gengenbachb, Mickey G. Husonc, et al.
a Deakin University, Institute for Frontier Materials, Pigdon’s Road Waurn Ponds Campus Geelong, 3216, Victoria, Australia
b CSIRO Materials Science and Engineering, Bayview Avenue, Clayton, 3168, Victoria, Australia
c CSIRO Materials Science and Engineering, PO Box 21, Geelong, 3216, Victoria, Australia

Within the last decade, carbon fiber reinforced composites have become regarded as the gold standard of high performance materials. Work toward understanding the roll of interfacial adhesion received a lot of attention in the 1970’s and 80’s, and is only now experiencing a renaissance, with recent work reigniting the debate about the relative importance of chemical modification and fiber roughness. A great deal of research has been centered on the installation of oxygenated species (OH, COOH, C=O), to increase fiber hydrophilicity and enhance non-covalent interactions at the interface, with little focus on covalent interactions. Taking inspiration from the vast number of successful functionalisation methods employed in the use of carbon nanomaterials, a number of synthetic pathways were selected and trialed for application to carbon fiber.

The surface of both oxidized and unoxidized unsized carbon fiber was functionalized using an aziridine linking group derived from reactive nitrene species, and attempts were made to install pendant amines using amide chemistry. Successful surface functionalization using the nitrene approach was supported by X-ray Photoelectron Spectroscopy, in both oxidized and unoxidized carbon fiber. The chemical treatment protocols had a no significant impact on the tensile strength of the individual fibers, and Atomic Force Microscopy revealed that fibers undergoing these treatment methodologies remained intact, without creating additional surface defects.

How can organic chemistry be used to manipulate covalent interactions at the fiber/matrix interface, and does this effect composite performance.

Servinis L, Henderson LC, Gengenbach TR, Kafi AA, Huson MG, Fox BL. Surface functionalization of unsized carbon fiber using nitrenes derived from organic azides. Carbon. DOI: 10.1016/j.carbon.2012.11.051



82
RAMAN MICROSPECTROMETRY STUDY OF CARBONIZATION PROCESSES : A NEW RELEVANT TOOL FOR EARTH AND UNIVERSE SCIENCES
Jean-Noël ROUZAUDa,*, Damien DELDICQUEb, Emeline CHARONc, Maria-Fernanda ROMERO-SARMIENTOd
a CNRS
b ENS
c CEA
d IFPEN

It is widely accepted that the graphitization processes (i.e. increase of the graphene layer diameter and subsequent growth of graphite crystals) can be followed by Raman microspectrometry using the disappearance of the D band and/or the narrowing of the G band (1). In contrast, Raman microspectrometry only begins to be used to investigate the carbonization phenomena. During these low-temperature processes (< 1500°C at lab, < 500°C in Nature), heteroatoms are released and a pure sp2 carbon is obtained without noticeable layer growth. The corresponding Raman spectra of these usually very disordered carbons are complex, since several broad D bands are frequently superimposed and their attributions are hardly debated.

At the Carbon 2012 conference, we presented a preliminary work based on the evolution of Raman spectra as a function of the highest temperature of treatment (HTT) (2). We studied two well-known reference precursors (anthracene-based cokes and saccharose-based ones). Among all the investigated Raman parameters, we detected that the full width at half-maximum of the D1 band located at about 1350 cm-1 (FWHM-D1), decreases linearly with HTT, in the 500-1500°C range. This relation appears to be respected, at least for these two chemically very different carbons. We therefore proposed to use the FWHM-D1 as a paleo-thermometer, and promising applications become possible in the archaeology field (e.g. measurement of firing temperatures of potteries). When other laboratory chars (from other organic precursors) or natural chars (including anthracites) are added in the diagram FWHM-D1 vs. the ID/IG intensity ratio, an unique narrow band is obtained. We named this trend as "carbonization path", which is clearly different to the graphitization line obtained with this diagram. The existence of such distinct relationships for carbonization and graphitization appears to be a major contribution of Raman spectroscopy for carbon science.

For the Carbon 2013 conference, we now propose new applications for other carbonization processes implying original extra-terrestrial carbons and unconventional source rocks (oil and gas shales). For extra-terrestrial carbons from differentiated meteorites, and their laboratory analogues (pyrolysed char-iron blends), the carbonization and graphitization trends can be clearly discriminated. The representative points of organic-rich shales are gathered outside the carbonization band; this behavior can be attributed to the presence of hydrocarbons still trapped within the organic mesoporous network. This could be a quick and relevant way to evaluate the retained hydrocarbon potential for such complex source rocks.

(1). O. MASLOVA, M.R. AMMAR, J.N. ROUZAUD, P. SIMON (2012) "Determination of crystallite size in polished graphitized carbon by Raman spectroscopy". Physical Review B, 86 (13), Article Number: 134205.

(2). J.N. ROUZAUD, D. DELDICQUE, B. VELDE. Raman microspectrometry study of carbonization processes. Annual world conference Carbon 2012 Krakow, June 17-22 2012



88
Electrochemical performance of boron-doped nanocrystalline diamond grown on carbon fibers
Adriana Azevedo, Maurício Baldan, Neidenêi Ferreira
Instituto Nacional de Pesquisas Espaciais

Boron-doped nanocrystalline diamond (BDND) films were studied on carbon fibers (CF) substrates produced from an organic polymer (polyacrylonitrile) at two heat treatment temperatures (HTT) of 1800 and 2300 K. The fibers were treated using two grain size of diamond powder: 0.25 mm in hexane solvent and 4 nm in KCl solution. Both prepared by ultrasound powder dispersion. The films were produced using Hot Filament CVD technique on carbon fibers substrate with a 900 K, 4.0 kPa, gas mixture of CH4/H2/Ar (1/19/80 sccm) and deposition time of 20 hours. During the deposition, fiber etching and diamond nucleation occur simultaneously and compete kinetically. Boron doping was obtained by forcing H2 through a bubbler with B2O3 dissolved in methanol that corresponds to 20,000 ppm of boron atoms in relation to the carbon atoms. This boron doping level corresponds to the acceptor density values around 1021 B cm-3 evaluated by Mott-Schottky plot analysis. The morphology and quality of the BDND electrode were characterized by scanning electron microscopy and by Raman scattering spectroscopy. Their electrochemical behavior was studied by cyclic voltammetry measurements. It discussed the HTT influence on substrate structural properties correlated with diamond film growth and their electrochemical response. The results showed evidence of large surface area increase, which makes them appropriated to be used as porous electrodes in different electrochemical applications.



90
Understanding and controlling the spontaneous attachment of polycyclic aryldiazonium salts onto amorphous carbon substrates
Deirdre M. Murphy, Ronan J. Cullen, Dilushan R. Jayasundara, Paula E. Colavita, et al.
School of Chemistry, Trinity College Dublin, College Green, Dublin 2, Ireland

Researchers are constantly looking for new methods for the modification of carbon materials and nanomaterials in a controlled and tunable way. Functionalisation of carbon substrates using aryldiazonium salts is a widely used methodology; however, a clear understanding of how carbons properties affect rates and yields of this chemisorption reaction has not yet emerged. We have chosen to investigate reactions at amorphous carbon surfaces as their electronic structure and chemical composition can be adjusted over a wide range, thus allowing us to develop a systematic approach for understanding the chemistry which occurs at the carbon/solution interface.

Diazonium salts of two nitro-substituted polycyclic aromatic compounds were synthesized and an experimental investigation into their spontaneous grafting onto amorphous carbon surfaces of controlled electronic properties is presented. The spontaneous covalent attachment of aryldiazonium salts onto disordered carbon surfaces was examined via electrochemical and spectroscopic techniques. In situ spectroscopic monitoring of the grafting of these compounds at the carbon/solution interface via Attenuated Total Internal Reflection Fourier Transform Infrared spectroscopy (ATR-FTIR) allowed us to follow the adsorption onto the surface. Further evidence of the grafting behaviour is provided via ex situ electrochemical analysis. The electronic properties of the carbon surfaces were characterised via a combination of X-ray and Ultraviolet Photoelectron Spectroscopy (XPS and UPS) and electrochemical impedance spectroscopy (EIS).

Firstly, we investigated the influence the structure of the aryldiazonium salt has on the grafting. We found that differences in the electron density at the carbon atom bound to the diazonium group are responsible for the differences observed in spontaneous attachment at amorphous carbon surfaces. Secondly, we reported on the effect that changing the sp2 content of the carbon substrate has on the rate, yield and mechanism of the spontaneous chemisorption of aryldiazonium salts. We report a change in chemical selectivity at disordered carbon surfaces which can be correlated to a change in the substrate electronic properties.

In conclusion, adsorption rates of the two positional isomers were found to be controlled either by the charge-transfer mediated adsorption or by the dediazoniantion-chemisorption steps, depending on the electronic properties of the carbon substrate. These results suggest that aryldiazonium salt adsorption rates at carbon surfaces can switch from being controlled by molecular electron accepting properties to being controlled by surface electron donating properties. This work highlights the importance of substrate choice in spontaneous grafting reactions and provides further mechanistic insight into the reliance of adsorption on structural and substrate composition.



93
ACTIVATION OF WASTE TYRES CHAR BY CYCLIC LIQUID-PHASE OXIDATION
Francisco Heras, Diana Jimenez-Cordero, Miguel Angel Gilarranz, Noelia Alonso-Morales, Juan Jose Rodriguez
Autónoma University of Madrid

In this work the preparation of activated carbon from chars obtained using waste tyres rubber as raw material upon cyclic activation using liquid oxidants is studied. Activation of waste tyres char was performed by successive cycles of liquid-phase oxidation followed by desorption in inert atmosphere at 650oC. The oxidation with nitric acid and hydrogen peroxide allowed higher porosity development than ammonium persulfate oxidation, and a char particle size of 1 mm was found as the most convenient. Up to 15 activation cycles were performed, showing a monotonical increase of burnoff with the number of cycles, which was higher in the case of nitric acid. Within the range tested (15-30% w) a higher concentration of oxidant led to higher burnoff, especially in the case of hydrogen peroxide, but no differences were observed in terms of BET surface area (SBET) developed per unit of burnoff. SBET values around 750 and 400 m2/g were obtained by activation with nitric acid and hydrogen peroxide, respectively. The activated carbons prepared by activation with nitric acid showed a much higher contribution of microporosity and a somewhat higher mesopore volume. The comparison with air activation by cyclic oxygen chemisorption-desorption shows that liquid phase oxidation provides higher porosity development, but at the expense of higher burnoff, which beyond a certain limit is detrimental for the mechanical stability of the particles thus impeding to obtain granular activated carbon.



94
Friction reduction mechanisms of 0D nanoparticles: fluorinated carbon blacks as promising new additives for lubrication
Philippe Thomasa,*, Jean-Louis Mansota, Elodie Disab, Marc Duboisb, Katia Guerinb, et al.
a Groupe de Technologie des Surfaces et des Interfaces, Université des Antilles et de la Guyane
b Institut de Chimie de Clermont-Ferrand-Matériaux Inorganiques

Since 20 years [1], new lubrication strategies consist in the use of solid nanoparticles in dispersion in lubricating oils and greases. The great interest of such nano-additives is due to the formation of a protective tribofilm on the rubbing surfaces without any chemical reaction with the substrates [2]. Previous studies pointed out the promising friction reduction properties of 2D (nanodiscs) and 1D (nanofibres) fluorinated carbon nanophases associated both to fluorination and lamellar structure of the particles [3,4]. We showed that the structure of the associated tribofilms depends on the initial shape of the fluorinated particles, inducing different friction reduction mechanisms. In the present work, the friction behaviour of 0D (nanospheres) fluorinated carbons is investigated. For this purpose, graphitized carbon blacks are fluorinated under F2 atmosphere or using TbF4 as fluorinating agent in controlled conditions in order to obtain atomic F/C ratios ranging from 0 to 1. The tribologic properties of the resulting compounds are investigated as a function of the fluorination rate. Special attention is paid to the determination of the structural parameters of the initial particles and associated tribofilms (Raman spectroscopy, scanning and transmission electron microscopy experiments). The tribologic properties are correlated to the structure of the initial nanoparticles and resulting tribofilms in order to identify their respective role in the friction reduction processes.

ACKNOWLEDGEMENTS

The authors acknowledge the French research department, the Conseil Régional de la Guadeloupe, the Fond Social Européen (FSE) and Fonds Européens de Développement Régional (FEDER) for their financial supports.

[1] J.L Mansot, M. Hallouis and J.M Martin, Colloids and Surfaces A, 75, (1993), 25

[2] J.L. Mansot, J.M. Martin, Y. Bercion, L. Romana, “Nanolubrication”, Brazil. J. of Phys., 39, 1, (2009), 53

[3] P. Thomas, D. Himmel, J.L. Mansot, M. Dubois, K. Guerin, W. Zhang, A. Hamwi, Tribo. Lett., 34, (2009), 49

[4] P. Thomas, D. Himmel, J.L. Mansot, W. Zhang, M. Dubois, K. Guerin, A. Hamwi, Tribo. Lett., 41, (2011), 353



95
Preparation and characterization of chemically activated carbon from sugar cane bagasse
Fernanda Seixasa,*, Franciele Turbianib, Renata Padilhaa, Marcelino Gimenesa, Nádia Fernandes-Machadoa, et al.
a Universidade Estadual de maringá
b Universidade Tecnológica Federal do Paraná

This work aims at the production of activated carbons from sugarcane bagasse. It was used a chemical activation process in which two chemical agents were tested (NaOH and ZnCl2). The bagasse was carbonized at different temperatures (500, 600 and 700 °C) and subsequently subjected to a chemical activation with NaOH or ZnCl2 in a mass ration of 3:1 (chemical agent:bagasse), under a flow of N2 at 600 °C for 1 h. The carbons were characterized by nitrogen adsorption isotherms (77 K), morphology by scanning electron microscopy, X-ray diffraction and thermo gravimetric analysis. The specific area of calcined carbons at different temperatures ranged between 309 and 431 m2/g, being micro and mesopores predominant in the pore size distribution. The samples showed average pore radius ranging between 16 and 20 Å. Among the two chemicals used, the NaOH demonstrated better performance in the development of the surface area of the material. In this case, the chemically activated carbons presented specific surface area between 370 and 1328 m2/g. The activation process promoted a significant increase in the micro porosity of the material, demonstrating with this, excellent perspectives concerning the use of this activated carbons in adsorption processes of both gases and solutes from aqueous solution.



96
Atomically one-dimensional crystals of metallic sulfur in carbon nanotubes
Fujimori Toshihikoa,*, Morelos-Gomez Aarona, Zhu Zhenb, Muramatsu Hiroyukic, Kaneko Katsumia, et al.
a Shinshu University
b Michigan State University
c Nagaoka University of Technology

Elemental sulfur is one of the most important resources enormously reserved in nature, which has been widely utilized in the chemical industry mainly for the production of sulfuric acid and the vulcanization of rubbers. A key challenge in sulfur chemistry is to find out a potential application based on its rich, but still veiled physic-chemical properties. It is well-known that elemental sulfur, the most polymorphic element, is an insulative solid under ambient condition. Here, we report experimental and theoretical evidences on metallization of one-dimensional (1D) crystals of sulfur formed inside quasi-1D cavity of carbon nanotubes (CNTs), even under ambient pressure. High-resolution transmission electron microscopy reveals that atomistic structures of the encapsulated sulfur are linear or zigzag sulfur chains. Synchrotron X-ray diffraction presents asymmetric Bragg peaks, strongly indicating the formation of the 1D crystals of sulfur inside CNTs. Lattice constants of the 1D crystals show good accordance with those evaluated by HR-TEM analysis. Our theoretical calculations based on ab initio density functional and quantum transport calculations show that electronic properties of zigzag or linear sulfur chains are metallic. To assess our prediction, we performed direct-current electric resistance measurements by the four-probe method at T=2-300 K. We found that resistivity significantly decreases by filling the 1D crystals of sulfur. Based on the variable range hopping model, an additional electron path is formed by the encapsulation. This experimental result reflects the 1D crystals of metallic sulfur. Raman spectroscopy also supports the metallic phase of sulfur; an asymmetric Breit-Wigner-Fano (BWF) line, which is assigned to the phonon mode of metallic-CNTs, is enhanced by the encapsulation. The most importantly, nearest-neighbor contact between the 1D crystals and metallic-CNTs plays an important role for enhancing the BWF line, so that the additional electron path can be ascribed to the 1D crystals of sulfur encapsulated in metallic-CNTs. These results lead us to believe that the 1D crystals of sulfur are indeed metallic. In conclusion, we identified the 1D crystals of metallic sulfur in inside the cavity of CNTs. The most noteworthy achievement of our study is the discovery of metallization of elemental sulfur at ambient pressure, while bulk sulfur requires ultra-high pressures exceeding 90 GPa. The present finding will pave the way to further development for future CNT-based nanotechnology utilizing enormous amount of elemental sulfur reserved in nature.



97
Photocatalytic performance of hybrid Bi2WO6-carbon composites under UV and visible light
R.J. Carmonaa,*, S. Murcia Lópezb, J.A. Navíob, M.C. Hidalgob, C.O. Aniaa
a Instituto Nacional del Carbón (INCAR, CSIC), Oviedo 33080, Spain
b Instituto de Ciencia de Materiales de Sevilla (ICMS, CSIC-Universidad de Sevilla), Sevilla 41092, Spain

In the last years, photo-catalytic degradation of hazardous organic compounds has proven to be a promising technology for wastewater remediation. For this reason, most research efforts are currently being directed to the development of novel photo-catalysts capable of promoting the complete mineralization of the pollutant, while maintaining an easy recovery from the reaction media and reutilization. Among different approaches, the incorporation of carbon as additive to semiconductors has recently proved to be an attractive strategy to improve the photocatalytic efficiency of the hybrid carbon/semiconductor composites on the photodegradation of a variety of recalcitrant pollutants. More recently, the self-photochemical activity of certain activated carbons under UV irradiation in the absence of conventional semiconductors has been demonstrated [1,2]. However, the challenge in photocatalytic applications still remains to improve the efficiency of theses systems under visible light, so as to obtain a higher use of the solar spectrum.

In this regard, the objective of this work was the synthesis of Bi2WO6/carbon composites with modulated properties for an enhanced photodegradation of aromatic compounds from aqueous solution. For that purpose, the formulation of the semiconductor [3] was modified with various carbon nanostructured materials covering carbon nanotubes, spheres obtained from hydrothermal carbonization, and activated carbons. All the materials were exhaustively characterized by various techniques (gas adsorption, SEM, TEM, XRD and TGA), and photocatalytic reactions were carried out in aqueous solution to evaluate the photodegradation efficiency of the hybrid composites, and to link these photochemical behaviour with the structural, chemical and textural properties of the incorporated carbon nanostructures added in the catalysts formulation.

References

[1] R. Leary, A. Westwood, Carbonaceous nanomaterials for the enhancement of TiO2 photocatalysis, Carbon 49, 2011, 741-72.

[2] L.F. Velasco, I.M. Fonseca, J.B. Parra, J.C. Lima, C.O. Ania, Photochemical behaviour of activated carbons under UV irradiation, Carbon 50, 2012, 249-58.

[3] S. Murcia López, M.C. Hidalgo, J.A. Navío, G. Colón, Novel Bi2WO6-TiO2 heterostructures for Rhodamine B degradation under sunlike irradiation; J. Haz. Mater. 185 2011, 1425-1434.



99
Hard carbon prepared from coal tar pitch using as anode material for Li-ion batteries
Mingwei Lia,*, Chengyang Wangb, Zhihua Guob, Mingming Chenb
a School of Science, Tianjin University, Tianjin 300072, China
b School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China

A hard carbon (HC) material was prepared from isotropic coal tar pitch (CTP) with a high softening point around 270 ºC by carbonizing the CTP at 800 ºC after the CTP being oxidized at 330 ºC at first. Field emission scanning electron microscope (FESEM), high-resolution transmission electron microscope (HRTEM), Raman microscope, X-ray diffraction, and BET analysis indicate that the as-prepared CTP-HC material has a microporous structure and contains graphite-like micro-crystallites. The elemental analysis indicates that CTP-HC consist of about 85.0 wt.% C, 1.6 wt.% H and 1.3 wt.% N. The CTP-HC was employed to prepare the anode material for Li-ion batteries, whose reversible capacity is about 576 mAh g-1 with a corresponding coulombic efficiency of 69.5% at a current density of 0.1 C (37.2 mA g-1). After 30 cycles, it still exhibited a stable reversible capacity of 351 mAh g-1. Moreover, the CTP-HC exhibited a reversible capacity of 145 mAh g-1 at a current density of 5 C (1860 mA g-1), which is much higher than that value (36 mAh g-1) of commercial graphitized mesocarbon microbeads (g-MCMB). The excellent electrochemical performance of CTP-HC is attributed to its high porosity and graphite-like micro-crystallites.



101
Carbon as a Catalyst Support for Catalytic Supercritical Water Gasification (CSWG) of Microalgae for Bio-Synthetic Natural Gas (Bio-SNG) Production (SunCHem Project)
Gaël Penga,*, Frédéric Vogela, Christian Ludwigb
a Paul Scherrer Institut (Switzerland)
b Ecole Polytechnique Fédérale de Lausanne (Switzerland) and Paul Scherrer Institut (Switzerland)

Over the last 10 years there has been increasing interest in using microalgae as a biofuel source. Microalgae are a promising bio-resource since they do not engender any competition with food crops and show higher photosynthetic efficiency and biomass production rates compared to other plants. Up to now, the current technology for biofuel production from wet biomass is facing diverse problems, such as high energy consumption and residence times (> 20 days) for the anaerobic digestion. Therefore, CSWG appears to be the most promising alternative since wet biomass (mH20 > 60 wt. %) can be processed with very good thermal efficiency (60-70 %), avoiding the biomass drying step and offering short residence times (< 30 min). The SunCHem project aims at demonstrating the technical and economic feasibility of Bio-SNG production from microalgae using CSWG by building a small process demonstration unit operating in continuous mode. In order to achieve full biomass conversion as well as a good Bio-SNG selectivity, a catalyst is needed. Supported ruthenium catalysts have already been reported to be the most suitable catalytic system. Unfortunately, only a few catalyst supports are stable in hydrothermal conditions like certain metal oxides (ZrO2, α-Al2O3, rutile-TiO2) or carbon. The motivation for using carbon is mainly due to its higher surface area compared to metal oxides, thus allowing for a higher ruthenium dispersion. Unfortunately, there is still a lack of knowledge about the interdependence between catalyst formulation and structure and its catalytic performance which is the key to further advance the effectiveness of Ru/C catalyst for CSWG. There is a necessity to assess the most relevant properties of carbon on the catalytic performance like the effect of meso/microporous structure, impurities (e.g. sulfur), carbon surface acidity and the graphitization degree. First results have shown that the structure of highly porous carbon is stable in supercritical water (420 °C and 350 bar). Temperature programmed desorption (TPD) as well as Boehm titration have revealed that a support pre-treatment with HNO3 prior to impregnation with RuCl3 adds functional groups to the carbon surface (mainly carboxylic/lactonic groups). In addition to HNO3 pre-treatment, heat treatment under He up to 450 °C was performed in order to remove less thermally stable functional groups like carboxylic groups for assessing the influence of these groups on the metal dispersion. CO pulse chemisorption has shown that the anchoring groups were favourable for Ru dispersion. Interestingly, carboxylic groups appeared to play a key role in achieving high metal dispersion. Furthermore, CNS elemental analysis has shown that a fraction of sulfur was removed by HNO3. It was suspected that sulfur within the carbon support negatively affects the catalytic performance by carrying out CSWG with isopropanol while a high metal dispersion was beneficial. In conclusion, although carbon materials appear to be a promising catalyst support for CSWG, preliminary results have revealed that its pre-treatment prior to metal impregnation is required for enhancing the catalytic performance. In the future more research should be undertaken to develop other pre-treatment methods for a more efficient carbon support cleaning.



104
Hierarchical structure of SWNTs with fully accessible surface
Alexandre Desforges, Brigitte Vigolo, Emeline Remy, Sébastien Fontana, Sébastien Cahen, et al.
Institut Jean Lamour (IJL), CNRS-Université de Lorraine, BP 70239, 54506 Vandoeuvre-lès-Nancy, France

Due to their combined superior chemical and physical properties, carbon nanotubes and in particular single walled carbon nanotubes (SWNTs) are recognized to have a huge potential in many fields of application. Production of hierarchical macroscopic structures of SWNTs offers a great opportunity to develop high-performance materials [1]. A multi-step and integrated approach to process SWNTs and obtain macroscopic self-assembled pure SWNT-based materials is presented. High-quality dispersion of purified SWNTs [2] is first induced in polar solvent due to their preceding reduction reaction with an alkali metal. The unzipping process occurring at this stage leads to ramified SWNTs [3]. They can be then self-assembled by attractive intermolecular forces through a controlled destabilization of the dispersion by oxidation. Swollen gels of SWNTs are formed at the air/solvent interface. After freeze-drying, the SWNT-based material shows a hierarchical structure with an evidenced high connectivity. The proposed procedure is able to preserve the debundled state of the SWNTs throughout the applied treatments. These self-assembled SWNT materials show an improved adsorption capacity compared to that of the non-processed SWNTs. We show that the increase in surface is mainly due to an addition of the microporous volume and that the external surface is twofold greater than before. These 3D SWNT assemblies certainly have many potential applications including storage and catalysis.

[1] Luqi Liu , Wenjun Ma, Zhong Zhang. Macroscopic Carbon Nanotube Assemblies: Preparation, Properties, and Potential Applications. Small 2011, 7, 1504–1520.

[2] Guillaume Mercier, Claire Hérold, Jean-François Marêché, Sébastien Cahen, Brigitte Vigolo. Method of purifying carbon nnaotubes. European Patent, WO 2012/056184 A2, 2012.

[3] Brigitte Vigolo, Claire Hérold, Jean-François Marêché, Patrice Bourson, Samuel Margueron, Jaafar Ghanbaja, Edward McRae. Direct Revealing of the Occupation Sites of Heavy Alkali Metal Atoms in Single-Walled Carbon Nanotube Intercalation Compounds. Journal of Physical Chemistry C 2009, 113, 7624–7628.



105
Etch pits in graphite oxidized by O2 : kinetics, morphology, and zigzag/armchair site dynamics
Arnaud Delehouzéa, Gerard L. Vignolesa,*, Francis Rebillata, Jean-Marc Leyssaleb, Patrick Weisbeckerb, et al.
a University Bordeaux - LCTS
b CNRS-LCTS

Oxidation of graphite by O2 has been the subject of numerous experimental and modeling studies, with sometimes contradictory results. The questions of the etch pits morphology (hexagonal or circular) and of the relation between etch kinetics of individual sites and apparent pit growth kinetics are still open.

To address those questions, we have conducted an experimental campaign featuring (i) an in-situ E-SEM study of pit growth under precisely controlled conditions either on pristine (1) or pre-pitted surfaces, (ii) an AFM study of the holes (1), (iii) a Electron Diffraction and Dark Field-TEM characterization of hole profiles assisted by an FIB sample preparation, and (iv) a TGA mass loss study.

The main conclusions are : (i) pits are hexagonal at low temperature and become circular above 1050K approximately (1), the transition being reversible (ii) the transverse morphology goes from a « flat bottom » shape at low temperature to a cup-like geometry at higher temperatures, (iii) the linear recession rate is constant whatever the hole size, and (iv) the hexagonal pits have zigzag edges only.

A numerical study has been performed by Kinetic Monte-Carlo (KMC) using three parameters as input: the three turnover frequencies of the zigzag, armchair and « pitting » sites (the third one represents the attack of a lower graphitic layer just below an existing hole edge). By parameter variation, all experimental morphologies have been found. Their value can be obtained as a function of temperature. We show that the apparent activation energy for linear recession rate is the arithmetic average of the zigzag and armchair rates. A dynamical model is identified from the KMC results: it shows a collaborative effect between these two kinds of sites instead of competition.

  1. A. Delehouzé, F. Rebillat, P. Weisbecker, J.-M. Leyssale, J.-F. Epherre, C. Labrugère, G. L. Vignoles, Appl. Phys. Lett. 99, 044102. (2011).


106
STUDY OF A CARBOXYGASIFICATION PROCESS FOR 14C DECONTAMINATION OF NUCLEAR GRAPHITE
Justin PAGEOTa,*, Lionel GOSMAINb, Jean-Noël ROUZAUDc, Damien DELDICQUEc, Laurence PETITd, et al.
a Andra, CEA, CNRS (France)
b CEA
c CNRS
d ANDRA

Graphite has been used in French gas cooled nuclear reactors (called UNGG) as a neutron moderator. Such reactors were shut down between 1968 and 1994. Their dismantling will generate significant amounts of waste including 23,000 tons of irradiated graphite. Several long term management options are being considered in France for graphite waste. Our study is focused on 14C partial decontamination as 14C is the main long-lived radionuclide in French graphite waste.

All along the reactor lifetime, graphite undergoes heavy damages due to neutron irradiation. An original and effective approach combining X ray diffraction, Raman Microspectrometry and High Resolution TEM was developed to access graphite multiscale organization. Irradiated graphites were post mortem sampled from different locations in the reactor core corresponding to different fluences and operating temperatures. If the structure of the most damaged samples is now completely turbostratic, drastic changes were also observed at the nanostructure scale (nm-µm range). HRTEM images show that pristine lamellar nanostructure was locally destroyed: the disorientation of nanometer-sized structural units is responsible for the occurrence of a microporous nanostructure, very similar to chars. As 14C is generated by neutron irradiation, we believe it is mainly located in the most structurally damaged areas. Our decontamination approach is based on this assumption.

Carbon reactivity towards gasification is governed by their multiscale organization [1]. Our basic idea to preferentially separate 14C from 12C graphite matrix is to use the strong differential reactivity between weakly irradiated 14C poor graphite and char-like 14C-rich highly irradiated graphite [2]. The preferential burn-off of the latter will allow a preferential release of the 14C, without a complete combustion of all the 12C carbon waste. We choose CO2 as the reactant, rather than steam or air, because of its high selectivity (the most disordered carbons, and then the most enriched in 14C, will be gasified in first) and its small reactivity with graphite. Moreover CO is the only product of the carboxygasification and is quite easy to manage.

To prove our basic hypothesis, carboxygasification of non-radioactive analogues (mechanically milled graphites [3]) was first carried out. The microporous turbostractic carbon was completely removed after few hours at 1000°C. Experiments are in progress on irradiated graphite waste to confirm that 14C is effectively released in first in the released CO. First results will be presented at annual world conference on Carbon.

[1] Rouzaud JN et al, 1991 : « Coke microtexture : one key for coke reactivity ». Fundamental issues in control of carbon gasification reactivity, p. 257-267.

[2] Rouzaud JN, Ammar MR, Gosmain L et al., A new way to decontaminate nuclear graphite wastes. Carbon 2011, Shangai.

[3] Salver-Disma F et al, 1999 : « TEM studies on carbon materials prepared by mechanical milling ». Carbon 37, p. 1941-1959



109
MECHANICAL PROPERTIES AND OXIDATION RESISTANCE OF C/C/CERAMIC COMPOSITES OBTAINED FROM PRECERAM
Teresa Gumulaa,*, Felix L. Martinezb
a AGH University of Science and Technology, Faculty of Materials Science and Ceramics, Al. Mickiewicza 30, 30-059 Krakow, Poland
b Universidad Politecnica de Cartagena, Departamento de Electronica y Tecnologia de Computadoras, 30202 Cartagena, Spain

The aim of this work was to investigate properties of inexpensive C/C/ceramic composites. C/C composites were obtained from phenol-formaldehyde resin and HTS 5131 carbon fibres (Tenax). Composites were impregnated with commercially available polysiloxane-based solutions of preceram (Lukosil 901 polysiloxane resin, Lucebni zavody, Czech Republic) and subjected to heat treatment at 1000oC, 1500oC and 1700oC. Mechanical properties and oxidation resistance of the composites were investigated. To determine mechanical parameters, the composite samples were investigated in three points bending test. Oxidation resistance of the samples was determined by mass losses of composites heated in air atmosphere in the temperature range from 600oC to 1000oC. Carbon-carbon composite without impregnation was used as a reference. Differences in mechanical properties between C/C reference samples and C/C/ceramic samples were observed. Composites subjected to heat treatment at 1500 and 1700oC exhibited lower values of Young’s modulus. At these temperatures, due to heat treatment of the composite samples, decomposition of impregnate occurs, what changes their fibre-matrix interface.

The applied densification procedure enhanced significantly oxidation resistance of composite samples. The best oxidation resistance represents C/C/ceramic composite heat treated at 1700oC.The reason for improved oxidation resistance of the composite is the presence of SiC protective layer on its fibre/matrix interface.

Acknowledgements

This work was supported by the National Science Centre, grant No. 2011/01/B/ST8/07451, decision No. DEC-2011/01/B/ST8/07451.



110
A simple electrochemical method for the preparation of carbon nanotube coatings inside capillary tubes
Carlos Sanchís-Bermúdez, Ángel Berenguer-Murcia, Ramiro R. Ruiz-Rosas, Emilia Morallón, Diego Cazorla-Amorós
University of Alicante

In the fields of both chromatography and microreactor technology, there is a substantial interest in the synthesis of coatings and fillings with controlled properties which could in turn enable the development of new columns or reactor configurations [1, 2]. In this respect, and given their interesting properties, carbon nanotubes (CNTs) would be a suitable candidate for the development of high surface-to-volume coatings with novel properties which may be highly useful both as separation columns or catalyst supports. The preparation of CNT deposits or coatings in the inner surface of capillaries has already been attempted from different perspectives [3,4], but all of them involve the growth of the CNTs inside the capillary, which poses a significant technological challenge since the tubes are commonly prepared from fused silica coated with a polyimide film, and thus is not exceedingly thermally stable. In this work, we propose a fast, simple and highly reproducible method for the coating of capillaries using a suspension of CNTs in water, which is the most user-friendly solvent available, using electrochemically assisted techniques. In order to put the results in perspective, the coating was also attempted by dip-coating of CNTs suspensions. In a first approach, CNTs were suspended in water using different mixtures of surfactantswhich were required in order to obtain stable enough suspensions. The CNTs were dispersed by using an ultrasonic probe. The as-prepared suspension was dip-coated in the inner surface of a fused silica capillary, but the results were not promising, especially due to the high concentration of surfactant(s) present, which resulted in large lumps containing CNTs present on the surface of the silica capillary. In order to overcome this problem, the CNTs were functionalized prior to their suspension in order to enhance their interaction with the aqueous solvent using an oxidizing agent at different temperatures. This treatment resulted in the oxygen content of the CNTs to increase dramatically. Functionalization of the CNTs resulted in a substantial improvement in their dispersibility, as revealed by the larger concentrations that could be achieved compared to our previous approach. These CNT suspensions were deposited inside the capillaries using a custom-built electrochemical cell. The CNTs suspension in water was used as the “electrolyte” solution. By controlling the current passed through the circuit and the time during which the electrodeposition is performed, it is possible to obtain full coverage of the inner surface of the capillaries by a fast, simple, cost-effective and highly reproducible method which shows great promise in the development of coatings technology.

References

[1] A. Sachse, A. Galarneau, B. Coq, F. Fajula, New J. Chem., 2011, 35, 259–264

[2] E.V. Rebrov, Á. Berenguer-Murcia, H.E. Skelton, A.E.H. Wheatley, B.F.G. Johnson, J.C. Schouten, Lab Chip, 2009, 9(4), 503-506

[3] M. Karwa, Z. Iqbal, S. Mitra, Carbon, 2006, 44, 1235-1242 [4] M. Karwa, S. Mitra, Anal. Chem., 2006, 78, 2064-2070

[4] M. Karwa, S. Mitra, Anal. Chem., 2006, 78, 2064-2070



111
HRTEM and Neutron diffraction: complementary tools for the production and validation of atomistic structural models of pyrocarbons.
Patrick Weisbeckera,*, Baptiste Farbosb, Jean-Marc Leyssalea, Gerard Vignolesc, Henry E. Fischerd
a CNRS, Laboratoire des Composites ThermoStructuraux, UMR 5801, 3 Allée de la Boétie, 33600 Pessac, France
b Laboratoire d’Intégration du Matériau au Système, UMR 5218 CNRS, 351 Cours de la Libération, 33405 Talence, France
c University Bordeaux, Laboratoire des Composites ThermoStructuraux, UMR 5801, 3 Allée de la Boétie, 33600 Pessac, France
d Institut Laue Langevin, 6 rue Jules Horowitz, BP 156, 38042, Grenoble Cedex 9, France

Pyrocarbons (PyCs) are deposits formed on a hot substrate by dehydrogenation of a gaseous hydrocarbon (Methane, Propane…). Their structures are based on turbostratic stackings of wrinkled and faulted hexagonal layers (i.e. with 5- or 7-atom rings, vacancies, dislocations…). The nanoscale organizations of the materials depend mainly on the nature of the gaseous precursor, the gas phase maturation and the temperature.

Atomistic models of two high textured PyCs (Rough Laminar and Regenerative Laminar) and a medium textured PyC (Smooth Laminar) have been produced from HRTEM images using an image guided atomistic reconstruction (IGAR) method [1]. This method and the resulting models will be briefly introduced before focusing on a careful experimental validation of the method. Especially, the IGAR method strongly relies on the construction of 3D images analogous to the 2D HRTEM images involving some strong hypotheses (analogy between 2D and 3D information, analogy between projected potential and image, orthotropy …). Using HRTEM image simulation from the atomistic models by a multislice image simulation program [2] we will thoroughly compare experimental and simulated images through various parameters: orientation angle, fringes lengths and tortuosity, etc… Results from neutron diffraction, obtained on the D4 diffractometer at ILL, Grenoble, like the pair distribution functions G(r) and structure factors S(Q) will also be presented to confirm the accuracy of the models. Possible experimental artifacts (mainly the resolution of the diffractometer in reciprocal space and the truncation-related ripples in real space) will be discussed and taken into account in our model’s validations.

[1] J.-M. Leyssale, J.-P. Da Costa, C. Germain, P. Weisbecker, G.L. Vignoles, Structural features of pyrocarbon atomistic models constructed from transmission electron microscopy images, Carbon, Volume 50, Issue 12, October 2012, Pages 4388-4400

[2] Kilaas R. Interactive software for simulation of high resolution TEM images. In: Proceedings 22nd annual conference of the microbeam analysis society, Kona, Hawaii; 1987. p. 293–300.



112
Hydrogen sensors based on metal nanoparticle-decorated carbon nanotubes
Jaime García-Aguilar, Izaskun Miguel-García, Ángel Berenguer-Murcia, Diego Cazorla-Amorós
University of Alicante

In the last decades, hydrogen sensors and detectors have been greatly improved. A new hydrogen sensors generation is now under development. In this respect, novel materials such as carbon nanotubes (CNTs) mixed with noble metals are showing promise in their use as sensors [1]. In this kind of sensors, CNTs act as nanowires, closing the electrical circuit. The function of the metal is to adsorb and/or absorb the hydrogen molecule while interacting with the CNTs. In this process the resistance of the circuit changes, thus becoming the necessary evidence for hydrogen detection [2]. This work has focused on the study of hydrogen sensors from the perspective of the metal employed and the solubilization and deposition of CNTs. Palladium has been the first candidate to incorporate into the sensor, however, considering the price, a nickel/palladium alloy has also been studied [3]. Moreover, in order to optimize the efficiency of the added metal, its addition was done in the form of nanoparticles. Another parameter which has a significant influence is the amount of metal loaded in the sensor. CNTs have been suspended in water using two surfactants to improve their solubility and dispersion, sodium dodecylbenzenesulfonate (SDBS) and poly-n-vynilpyrrolidone (PVP). The solution was prepared with the smallest concentration possible (0.25 mg/mL) to prevent CNTs agglomeration. Sensors have been prepared on glass slides using adhesive bands of copper as contacts for the electrical contacts in the multimeter. A sufficient amount of CNTs was added with a micropipette, and dried at 60ºC for 24h. Then, the necessary volume of nanoparticles suspension was deposited over CNTs and dried at room temperature. In order to characterize the sensor, they were tested in routine assays in a custom-built gas cell using a gas stream with a hydrogen concentration of 3.3%. The sensors which showed the best results were tested with different hydrogen concentrations. The obtained sensitivities towards hydrogen are comparable to other devices reported in the literature, even though the method described here is significantly different. Our method is simpler and more cost-effective than others found in the literature like sputtering or electron beam evaporation [4]. Some sensors (Pd/SWNT) showed a signal increase of the higher than 50% when exposed to hydrogen. Another key feature that this study has revealed is the importance of gaseous oxygen when hydrogen is the analyte. When another carrier gas (i.e. N2) was used instead of synthetic air, the sensors presented a markedly different behavior in the presence of hydrogen. The experience revealed that the reaction mechanism is more complicated and the reaction of water formation can play a fundamental role in the hydrogen detection process.

References

[1] D. R. Kauffman, A. Star, Angew. Chem. Intl. Ed., 47 (2008) 6550-6570.

[2] K. Toratania, D. Tsuya, M. Suzuki, K. Ishibashi, Physica E, 24 (2004) 46–49.

[3] S. Yuna, S. T. Oyama, J. Membr. Sci., 375 (2011) 28-45.

[4] R. Ghasempour, S. Z. Mortazavi, A. Irajizad, F. Rahimi, Int. J. Hydrogen Energy, 35 (2010) 4445-4449.



113
Photo Catalytic Behavior of Carbonaceous Material Containing Nitrogen
Masayuki Kawaguchi, Yuki Ishida
Osaka Electro-Communication University

Hydrogen can be made by the electrolysis of water and is used for the important fuel of the fuel cell. The present paper deals with the preparation of hydrogen by the electrolysis of water using a photo catalytic electrode made of carbonaceous materials containing nitrogen (C/N materials). There are not so many reports on the C/N materials which were applied to the photo catalytic material [1].

The C/N materials in the present study were prepared by the pyrolyses of organic precursors such as diaminomaleonitrile (composition: C4H4N4) and 2,3,6,7-tetracyano-1,4,5,8-tetraazanaphthalene (composition: C10N8) which are called AMN and CAN, respectively [2,3]. A C/N material prepared by the pyrolysis of AMN at 1020 K showed a structure similar to the non-crystalline carbon and had an approximate composition of C2N.

The C/N material was pasted on a platinum plate (surface area: 1 cm2) by using PTFE binder and used as the anode in 1 M-H2SO4 aqueous solution. Another platinum plate and Ag/AgCl electrode were used as the cathode and the reference, respectively. This system electrolyzed water under irradiation of visible light as well as UV-Visible light on the C/N material (anode) by applying 1 V vs. Ag/AgCl which is a voltage lower than the theoretical one (1.23 V). For example, photo catalytic currents of 28 µA and 70 µA were observed on the C/N material under visible light and UV-visible light, respectively. In the case of TiO2 anode, which is used as the photo catalytic material, photo catalytic currents of 0.2 µA and 3.1 µA were observed under visible light and UV-visible light, respectively by the same electrolytic condition described above. These results suggested that the C/N material electrolyzed water more effectively than TiO2, particularly under visible light.

References:[1] X. Wang, K. Maeda, A. Thomas, K. Takanabe, G. Xin , J. M. Carlsson, K. Domen, M. Antonietti, Nat. Mater, 8 (2009) 76-80. [2] M. Kawaguchi, T. Yamanaka, Y. Hayashi, H. Oda, J. Electrochem. Soc., 157 (2010) A35-A40. [3] M. Kawaguchi, A. Itoh, S. Yagi, H. Oda, J. Power Sources, 172 (2007) 481-486.



114
Transfer-Free Electrical Insulation of Epitaxial Graphene from its Metal Substrate
Paolo Lacoviga,*, Rosanna Larcipreteb, Matteo Dalmiglioa, Fabrizio Orlandoc, Alessandro Baraldic, et al.
a Elettra-Sincrotrone Trieste S.C.p.A.
b CNR Institute for Complex Systems, Rome, Italy
c University of Trieste, Italy and CNR-IOM Lab.TASC, Trieste, Italy

The remarkable properties of graphene, such as the very high carrier mobility at room temperature, tolerance to high temperature and inertness, make it the most promising candidate for future nanoelectronics. Several methods have been developed to produce graphene layers of various dimensions and quality, which, however, hardly match the requirements for mass production of electronic devices. From one hand, exfoliation-based techniques are very expensive, time-consuming and produce small flakes or graphene of poor quality; on the other hand large-scale growth on metal substrates is capable of large-area high quality layers, but requires the transfer of graphene on an insulating support in order to guarantee the conduction through graphene.

We have developed a novel transfer-free method to electrically insulate epitaxial graphene from the metal substrate it is grown-on. This is achieved by growing an insulating SiO2 layer of the desired thickness directly under the epitaxial graphene layer, through a stepwise reaction between intercalated silicon and oxygen [1,2].

Firstly, epitaxial graphene is grown on a Ru(0001) crystal surface. Subsequent exposure of the sample to a Si flux at 720 K results in Si intercalation and in the formation of Ru silicide below graphene. The final step consists of oxygen intercalation [3] at T=630 K: the Ru silicide is rapidly oxidized producing a thin SiO2 layer over an oxygen covered Ru surface. High resolution fast-XPS measurements carried on during the whole process demonstrate that graphene does not react with O2 and that during the decomposition of the Ru silicide oxygen binds exclusively to Si. At the end of the process, electrical insulation of the graphene layer from the Ru substrate has been demonstrated by performing lateral transport measurements with a microscopic 12 point probe, showing a resistance behaviour characteristic of two-dimensional transport [4].

The transfer-free method developed in the present work might have wide application in graphene research and nanotechnology devices fabrication.

References

[1] S. Lizzit et al. Nanoletters 12, 4503 (2012)

[2] Nat. Nanotechnol. Research highlight doi:10.1038/nnano.2012.183

[3] R. Larciprete et al., ACS Nano 6, 9551 (2012)

[4] R. Larciprete et al. J. Am. Chem. Soc. 133, 17315 (2011)



116
Study of ultra-microporous carbon nanostructures by Transmission Electron Microscopy : application to modeling of adsorption isotherms with Non Local Density Functional Theory accounting for pore wall corrugation
Pascaline Préa,*, Jacek Jagiellob
a (1) GEPEA, UMR CNRS 6122, Ecole des Mines de Nantes, 4 rue Alfred Kastler, 44307 Nantes Cedex 03, France
b (2) Micromeritics Instrument Corporation, 4356 Communications drive, Norcross, GA 30093, USA.

The ultra-microporosity of a set of different activated carbon materials was assessed from the measurements of CO2 and N2 adsorption isotherms obtained respectively at 273 and 77 K with a volumetric apparatus. The distribution in the micropore volumes between the narrowest (less than 0,07 nm) and the upper size range (up to 2 nm) was determined from the Dubinin –Radushkevich model, applied respectively to the CO2 and N2 experimental adsorption isotherms. Based on the results obtained, it was shown that depending on the material, the nitrogen molecules could be partially adsorbed in the ultra-microporosity or be completely prevented to penetrate the ultra-micropores. These results suggest that the material nanostructure, which determines the micropore morphology and its connectivity, plays a significant role on the nitrogen diffusion at low temperature and on in its adsorption capacity in the narrowest pores. In an attempt to explain the influence of the carbon nanostructure on the CO2 and N2 ultra-micropore adsorption capacities, the materials were characterized by High Resolution Transmission Electron Microscopy (HRTEM) image processing. For that purpose, an original approach was employed which relies on image morphological analysis techniques [1]. The image analysis enables to characterize the geometry and the arrangement of the fringes representative of the graphene-like sheets seen edge on. The procedure applied has pointed out different degrees of disorder of the material nanostructures, associated to the size of the continuous domain, which were defined as assemblies of nearly parallel fringes following a common orientation. Besides, the probability density functions of the fringe lengths, tortuosities and local curvature radii were computed and statistical means were derived. The mean geometrical parameters were used in order to design a slit-shape micropore model accounting for local curvature of the defective graphene walls. The ultra-micropores were so assumed to be ideally represented by spaces separated by two semi-infinite corrugated graphene walls, which shape could be analytically described by a sine curve. The amplitude and the period of the sine function were defined to fit the mean geometrical parameters of the fringes determined from the HRTEM image analysis. These pore structures were used to compute the gas adsorption isotherms on the basis of the Non Local Density Functionnal Theory (NLDFT). So defined, the micropore model introduces heterogeneity of the adsorption potential which is shown to be enhanced in the cavities formed by the local curvatures of the walls, and to result in significant variations of the local density of the adsorbed phase within the pore. According to this model, the improvement in the prediction of the gas adsorption isotherms by the NLDFT method was assessed by comparison with the experimental data. In addition, the agreement between the ultra-micropore size distributions computed from the modified NLDFT model and the effective inter-fringe space distributions determined from the HRTEM image analysis was examined.

[1] Pré P et al., 2013, Carbon, 52, 239-258.



118
Preparation of activated carbons from agricultural wastes for CO2 capture from flue-gas
Marco Balsamoa, Temenuzhka Budinovab, Alessandro Ertoa,*, Amedeo Lanciaa, Nartzislav Petrovb, et al.
a Dipartimento di Ingegneria Chimica - Università di Napoli
b lab. Chemistry of Solid Fuels, Institute of Organic Chemistry, Bulgarian Academy of Sciences

The increase in worldwide CO2 emissions, mainly deriving from fossil fuel combustion, has forced the scientific research to the development of new and efficient technologies for CO2 capture and storage. Post-combustion solutions, such as adsorption, gas separation membrane, cryogenic separation, etc. seem to have the greatest near-term potential. In particular, the adsorption process represents a very promising technology, widely used for gas treatments due to its good removal efficiency, great versatility and, if coupled with an effective regeneration process, for the absence of by-products. Many different sorbents can be used on purpose; activated carbons (AC) are generally less costly than other materials (e.g., zeolites, ordered mesoporous silicas, metal organic frameworks, etc.), and in some cases they also show comparable adsorption capacity. The high potentiality of AC for CO2 capture relies in their complex structure characterized by high surface area, tunable porosity and chemical surface properties. In particular, the presence of basic oxygen functionalities (such as chromene, ketone, pyrone, etc.) increases the affinity between AC surface and the acidic CO2 molecule.

In the last years, the production of activated carbon from waste materials has received increasing attention both to provide an alternative solution for the reutilization/disposal of such materials and to overcome the high cost related to commercial activated carbons. In particular, agricultural by-products have proved to be promising raw materials for the production of activated carbons because of their availability at a low price, good mechanical strength, and low ash content of the final product.

In this work, a pyrolysis process is employed for the production of new carbonaceous adsorbents from different agricultural by-products such as peach stones, apricot stones and olive stones. The process is carried out at 550°C with a heating rate of 10°C/min at atmospheric pressure, in a stainless-steel vertical reactor placed in a tube furnace. The pyrolyzed samples were subjected to activation with water vapor at 800°C for 1 h. The procedure followed for the synthesis of the adsorbents and the complete physico-chemical characterization of all the intermediates of the process are described to highlight its economic and technical properties. The results from N2 adsorption show that the synthesized activated carbons are characterized by a well-developed pore structure, with dominant content of micropores. The results from pore size distribution demonstrate that most of the pores are in the range 1-2 nm, whereas the BET surface area ranges between 800 and 1000 m2/g. All the samples have alkaline character of the surface.

In order to test the performances of the synthesized activated carbons, CO2 adsorption tests from simulated flue-gas have been carried out in a lab-scale fixed-bed column, at different temperature and CO2 concentration in order to investigate both kinetic and thermodynamic aspects.

All the synthesized adsorbents showed good CO2 adsorption capacity, the pore size and the chemical surface properties being the parameters with greatest influence. Adsorption rate increases with CO2 concentration and temperature, even if an increase in temperature significantly reduces the adsorption capacity. Finally, it was demonstrated that the adsorbents can be regenerated and used in consecutive adsorption-desorption cycles without any significant loss in their CO2 adsorption capacity.



119
Calcium phosphate coating on carbon fiber clothes for their use as biomaterial
Sylvie BONNAMYa,*, Quentin PICARDa, Jérôme CHANCOLONa, Sandrine DELPEUXa, Franck FAYONb, et al.
a CRMD/CNRS/University of Orleans, France
b CEMHTI/CNRS, ORLEANS , France

Due to their mechanical properties, carbon fibers have previously been considered for hard and soft tissue implanting. Due to the strong electrostatic forces within the cloth combined with a micro- and nanoporous texture, the carbon cloth has permeable properties which improve the breathability of the cloth. Despite the excellent biocompatibility of activated carbon fibers, considering their application in scaffolds or implants, biological activity needs to be enhanced. This is realized via the deposition of calcium phosphate phases (CaP) on the carbon substrate. Thanks to the excellent biocompatibility, bioactivity and osteoconductivity of calcium phosphate ceramics, especially hydroxyapatite (HA), carbon cloth-reinforced HA composites which combine the highly biocompatible CaP matrix with the properties of carbon fiber are promising bioceramic materials, particularly useful in the reconstruction of bone defects.

In our work, CaP coatings are performed on activated carbon clothes using a sono-electrodeposition method. This technique is well adapted to carbon materials because of their high electrical conductivity, especially in the case of fibers or fabrics behaving as self-standing and easily handling electrodes. The thickness and the chemical composition of the coatings can be well controlled using adequate experimental conditions of polarization, electrolyte pH and concentration. Sonication helps to increase deposition rates and efficiencies, deposit homogeneity, thickness, and hardness but also to improve the adhesion of the deposit to the carbon matrix electrode.

SEM, FTIR spectroscopy, X-ray diffraction and 31P NMR are used to characterize the morphology, chemical composition and structure of the carbon cloth-reinforced CaP composites and to identify the CaP phases. Various CaP deposit thickness with different morphologies (platelets or needles) are obtained depending on the polarization conditions.

To study the effect of CaP coatings on biological performance of the materials, in vitro biocompatibility tests are carried out using osteoblast-like cells.



120
Relationship between activated carbon fiber cloth’s structure and electrical resistance
David Johnsena,*, Hamidreza Emamipoura, Zhanquan Zhangb, Zifeng Yanc, Mark Rooda
a University of Illinois at Urbana-Champaign
b China University of Petroleum, University of Illinois at Urbana-Champaign
c China University of Petroleum

Electrothermal swing adsorption (ESA) with activated carbon fiber cloth (ACFC) can be used to selectively remove and concentrate an organic vapor/gas (e.g., toluene and isobutane emitted during coatings and manufacturing operations, respectively) from gas streams for reuse as a feedstock. ACFC’s electrical resistance is an important parameter for both the adsorption and regeneration cycles for ESA. During adsorption cycles, ACFC’s electrical resistance is affected by the adsorbed material and can thus potentially be used to determine when to end the adsorption cycle before the occurrence of adsorbate breakthrough. For regeneration cycles, the electrical resistance of the ACFC is also used to control the temperature of the adsorbent during electrothermal heating.

This research evaluates ACFC’s properties that affect its electrical resistance, particularly its physical and chemical properties as well as the affect of adsorbed materials. ACFCs with select levels of activation and thus different physical structures (i.e., microporous volume ranging from 0.40-0.74 cm3/g) were hydrogen treated at 900 oC to remove oxygen functional groups. Additionally, the ACFC with the lowest microporosity was treated with HNO3 to add oxygen functional groups. Bulk oxygen content and resistivity at a reference temperature of 273 K were measured for each sample. The resistivity values included the reduced cross-sectional area from the select levels of porosity in the ACFC samples. The hydrogen treated ACFCs with similar oxygen contents (2.0-2.4 wt%) had similar resistivity values (5.0x10-4 to 7.0x10-4 Ω-m). This similarity in resistivity suggests that resistivity differences between ACFCs with different activation levels are largely explained by the consideration of the effective cross-sectional area of the ACFC. The HNO3 treated ACFC with oxygen content of 8.5 wt% had a resistivity value of 1.5x10-3 Ω-m. This increase in resistivity compared to the hydrogen treated samples is attributed to the added oxygen functional groups providing a low energy state that localizes charge carriers. Thus, the porosity and oxygen functional groups both affect the ACFC resistivity.

The resistance of an untreated annular ACFC cartridge was measured during the adsorption of isobutane and acetone. ACFC’s electrical resistance decreased by 7.0 x 10-3 Ω/g adsorbed and 2.8 x 10-3 Ω/g adsorbed during the adsorption of isobutane and acetone at 2,000 ppmv in an air stream, respectively. Based on these results, it is hypothesized that the adsorbed isobutane and acetone increase the energy level at the oxygen functional groups, reducing the localization of charge carriers at these adsorption sites. The acetone would then have a lesser impact on ACFC resistance than isobutane because it contains oxygen, which localizes charge carriers in the adsorbate.

This study improves our understanding of the mechanisms impacting ACFC’s electrical resistance and will allow for the selection of desirable adsorbent properties for a simplified and lower cost ESA system that is controlled entirely based on in situ measurements of the ACFC’s electrical resistance and that is applicable for the abatement of a wide range of adsorbate pollutants.



123
Preparation of Electrochemical Characterization of Boron/carbon Material as an Anode of Sodium Ion Battery
Takayuki Kaseda, Masayuki Kawaguchi
Osaka Electro-Communication University

Boron/carbon (B/C) materials were previously prepared [1] and were applied to the anode of lithium ion batteries [2]. In the present study, we have prepared B/C materials and applied them to the anode of sodium ion batteries. We prepared B/C materials by chemical vapor deposition method using boron trichloride and ethylene as starting materials. Obtained films were dark gray in color. X-ray diffraction pattern indicated that materials prepared at temperatures between 1470 K and 1670 K had the graphite-like layered structure. However, materials prepared at temperatures 1770 K and higher than 1770 K contained B4C as well as the graphite-like layered material. ESCA analyses suggested that the material prepared at 1470 K had a chemical bond between boron and carbon with a composition of B0.52C. Sodium could be intercalated into the material prepared at 1470 K to be an intercalation compound by an electrochemical method in an electrolyte of 1 M-NaPF6 with a mixed solvent of ethylene carbonate (EC) and diethyl carbonate (DEC). A plateau at around 0.6 V vs. Na/Na+ was observed on the first discharge (intercalation) which might be due to the formation of solid electrolyte interface (SEI) similar to the case of the anode of lithium ion batteries. The plateau of SEI was not observed on second discharge and thereafter. Reversible discharge capacities of ca. 130 mAh/g were observed on the second discharge and thereafter. The capacity 130 mAh/g is comparable to that measured for the BC2N anode [3,4]. From these results, the B/C materials can be one of the candidates for the anode of sodium ion batteries.

References: [1] J. Kouvetakis, T. Sasaki, C. Shen, R. Hagiwara, M. M. Lerner, K. M. Krishnan, N. Bartlett, Synth. Met., 34 (1989) 1-7. [2] B. M. Way, J. R. Dahn, J. Electrochem. Soc., 141 (1994) 907-912. [3] M. Kawaguchi, K. Ohnishi, K. Yamada and Y. Muramatsu, j. Electrochem. Soc, 157 (2010) P13-P17. [4] K.Yamada, A. Kurasaki, M. Kawaguchi, Tanso, No.249 (2011) 161-167 [in Japanese].



130
Preparation and Properties of Adsorbents from Formed-wood with Binders
HONG Ikpyo, KIM Yong Jung, AN Jung Chul, PARK Sei-Min
Research Institute of Industrial Science & Technology(RIST)

The pellet-shaped activated carbons were prepared from carbonized wood pellets by reinforced with impregnants. The wood pellet was carbonized in inert atmosphere, pellet-shape char was obtained. After carbonization chars were still maintained shape of pellet but had not enough hardness to apply for activated carbon, so chars were impregnated with pitch or phenolic resin. The reinforced chars were further carbonized and activated in steam atmosphere at 800°C and finally pellet-shaped activated carbons with high hardness were obtained. The pore properties of activated carbons were evaluated and compared with commercial activated carbons. The pellet-shaped activated carbon is expected to be available replaced by the formed activated carbon.



132
The Synthesis of Graphene Films in the Combustion at Atmospheric Conditions
Nikolay Prikhodko, Bakhytzhan Lesbayev, Moldir Auyelkhankyzy, Zulkhair Mansurov, Yestay Ospanov
Institute of Combustion Problems

The results of the study of the formation of layered graphene films in premixed propane-oxygen mixture flames at atmospheric pressure under the following conditions are described: flow rate of propane - 219.1 cm3/min, the flow rate of oxygen - 381.2 cm3/min, that correspond to the ratio of C/O = 0.86. Studies were carried out with addition of argon to the propane-oxygen mixture in an amount of 300-650 cm3/min as well as without argon. As catalytic substrates copper and nickel plates placed in the center of the flame were used. The time range of the substrate in flame varied from 5, 10, 20, 30, 40, 60 seconds, 5 and 10 minutes, and the substrate angle varied relatively to the vertical axis of the flame: α = 0, 30, 45, 60, 85°. Flame temperature in the experiments was in the range 900-950 °С. Soot structure samples received on substrate were examined with Raman spectrometer NTEGRA Spectra at a wavelength λ = 473 nm. Analysis of the results showed that for formation of layered graphene films is preferred to use a nickel substrate. Copper substrate, having a predominantly superficial way of synthesis of graphene layers, does not give a distinct graphitized structure. In this case, the copper substrate is exposed to strong oxidation in the flame with formation on the surface of oxide film, flaking when cooling. It was determined that the minimum number of graphene layers (two or three layers, IG/I2D = 1.1-1.3) is observed in the range of nickel substrate angle from 0 ° to 30 °. A further increase of the substrate angle relatively to the vertical axis of the flame (over 30°) leads to increase of minimum number of graphene layers formed on substrate - from 5 to 10 (IG/I2D = 1.7-2.4). It was discovered that without the addition of argon on the substrate 5-10 graphene layers are forming (IG/I2D = 1.6-2.5). It was determined that the formation of graphene layers on the substrate occurs vertically on height of the flame with following proceeding to the soot structure.



133
Activated-carbon cloth supports umbilical-cord stromal stem cells growth and differentiation
Virgínea de Araújo Fariasa,*, Julia Sirés-Camposa, Jesús López-Peñalvera, Carlos Moreno-Castillab, José Mariano Ruiz de Almodóvara
a Centro de Investigación Biomédica, Universidad de Granada, Granada, Spain.
b Departamento de Química Inorgánica, Facultad de Ciencias, Universidad de Granada, Granada, Spain.

Bone is composed primarily of cells, collagen, fibre, hydroxyapatite and water, each hierarchical structural level contributing to its functional strength, ductility and toughnes. Biomaterial capable of promoting osteoregeneration would provide a promising solution for many common clinical procedures.

Activated-carbon cloth (ACC), which presents a large surface area and well-developed porosity, fulfils all three of the fundamental features of biomaterial thought to be important for effective bone regeneration: i) a physico-chemical structure and composition that supports cell growth and osteogenic and chondrogenic cell responses; ii) biocompatibility, with no release of toxic products; and iii) an adequate porous network to allow cell growth and the nutrition of inner cellular mass formed by the biomaterial. The ACC used as substrate in our experiments had a BET surface area of 2.089 m2/g and a total pore volume of 0.927 cm3/g, of which 84% were micropores with a mean width of 1.23 nm and the remaining 16% were mesopores with widths of between 2 and 4 nm. One of the characteristics of the porosity of ACC in comparison to other porous carbons is that the micropores are perpendicular to the fibre axis and are thus directly open to the surface.

Living cells are known to adhere to the surface of activated carbon via adsorption (LópezPeñalver et al., 2009)and so we hypothesized that ACCs may be useful materials to support stem-cell growth since repeated passaging in conventional cell cultures reduces the pluripotency and proliferation capacity of human mesenchymal stem cells (MSCs) because of exposure to enzymes that degrade cell-surface proteins (trypsin, for example), thus calling for new stem-cell culture procedures. Umbilical-cord stromal stem cells (UCSSCs) have been shown to be biologically equivalent to bone-marrow MSCs (Farias et al., 2011)and are emerging as an interesting alternative to bone-marrow-derived cells because: i) they are obtained by non-invasive means; ii) they meet International Society of Cellular Therapy criteria; and iii) they have been successfully differentiated to adipocytes, chondrocytes and osteocytes, hepatocyte-like cells, endothelial and neuronal cells.

We have investigated the capacity of ACC to support growth and differentiation of UCSSCs. Immunoflourescence staining revealed extensive expression of collagen in all the samples, and collagen type II and osteopontin within the samples cultivated in specific differentiation-inducing media. Our results demonstrate that an activated-carbon cloth provides the adequate scaffold conditions for the development of cell-derived matrix proteins and facilitates the growth of undifferentiated stem cells with the ability to induce osteogenic and chondrogenic differentiation. The formation of cells, natural collagen, calcium-magnesium carbonate and hydroxyapatite crystals, together with the self-assemblage of the collagen to produce suprafibrillar arrangements of fibrils all occur simultaneously on the scaffold and can be studied together ex vivo under physiological conditions. In particular, the spontaneous differentiation of stem cells cultured on activated-carbon cloth without extra osteogenic supplements suggests new possibilities for the treatment of traumatic and degenerative bone diseases.

López Peñalver J, et al. Carbon 2009;47(15):3574-3577.

Farias VA, et al. Placenta 2011 Jan;32(1):86-95.



134
Competitive adsorption of binary vapor mixtures on activated carbon filters
Inna Berezovska, Peter Lodewyckx
Royal Military Academy, Department of Chemistry, Renaissancelaan 30, B-1000 Brussels, Belgium

It is assumed that accurate prediction of breakthrough time of binary organic mixtures is strictly correlated with competitive phenomena inside activated carbon filters. In this work we propose a detailed study of the influence of different parameters on the capacity of activated carbons and the kinetic profiles of adsorption in the presence of binary organic mixtures. Analysis of the breakthrough curves of mixtures and independent modeling of the “overshoot” of the more volatile vapor will be presented, with the aim to be applied for the prediction of breakthrough times of activated carbon filters.



136
Graphene p-n vertical junctions showing rectifying behaviors at large n doping concentrations
Suk-Ho Choi, Sung KIm, Dong Hee Shin, Chang Oh Kim
Kyung Hee University

Formation and characterization of graphene p-n junctions are of particular interest because the p-n junctions are used in a wide variety of electronic/photonic systems as building blocks. We firstly fabricate and characterize vertical-type graphene p-n junctions. Single-layer graphene was synthesized by using chemical vapor deposition, and transferred on SiO2/Si substrates. For the formation of graphene p-n junction, a solution of benzyl viologen (BV) was first dropped and spin-coated on the 10 x 10 mm2 graphene/SiO2/p-type Si wafer, and then annealed at 100 oC for 10 min to make graphene uniformly n-type. Subsequently, a 5 x 5 mm2 bare graphene was transferred on ~1/4 area of the n-graphene/SiO2/p-type Si wafer, a solution of AuCl3 was dropped and spin-coated on the surface of graphene, and similarly annealed. As a result, the graphene p-n vertical junction was formed on the ~1/4 area of the SiO2/p-type Si wafer. 1-mm-diameter Ag electrodes were deposited on the top of both n- and p-graphene layers to complete the graphene p-n device. We prepared the p-n junctions for various n doping concentrations at a fixed highest p-doping concentration. At lower n doping concentrations, the p-n junctions are ohmic, consistent with the Klein-tunneling effect. In contrast, at higher n doping concentrations, the p-n junctions show asymmetric rectifying behaviors. We also report high-efficient photocurrent (PC) behaviors of these graphene p-n jucntions. The observed rectification and PC characteristics of the graphene p-n vertical junction well follow what are expected from its band structure and the tunneling of current through the insulating or semiconducting interlayers formed between the metallic p- and n-graphene layers.



137
Highly efficient quantum molecular sieving of 13CH4 and 12CH4 using nanocarbon with the aim of 14C separation from nuclear wastes
Katsumi Kaneko, Daiki Minami, Toshihiko Fujimori
Research Center for Exotic Nanocarbons, Shinshu University

There are many graphite type nuclear plants (at least 116) which do not work all over the world. In the graphite type nuclear plant, a plenty of 14C (about 1-2%) deposits in graphite on collision with neutrons. Each graphite type nuclear plant has radio-graphite wastes of about 2000 t and 20 t of 14C, being a large amount of radiocarbon wastes. The whole amount of radioactive 14C-graphite from 116 graphite type nuclear plants is estimated to be more than 2000-4000 t.If 14C is burned into CO2, it is predicted to increase the atmospheric concentration of 14CO2 by more than 50 times higher of the present atmospheric 14C level . The huge amount of 14C is incorporated in organic matter through photosynthesis, becoming available for incorporation in the food chain. Consequently, human has a great cancer risk of human organs by continuous irradiation with electrons from 14C, because the half life of 14C is 5730 years.

Therefore, we must innovate a completely new control route of the 14C-graphite wastes. As controlled oxidation of graphite into CO2 and the successive reduction of CO2 into methane are already established, the development of the highly efficient separation of methane isotopes enables to concentrate 14C-methane to useful carbon nanotube.

We propose the quantum molecular sieving separation (QMMS) of 14C in the form of methane using the recently developed technique (1). We found that single wall carbon nanohorn (SWCNH) was highly efficient for separation of 13CH4 from 13CH4-12CH4 mixture at 112 K. Also SWCNH gave a great difference in equilibrium adsorption amount of 24 % between 13CH4 and 12CH4. The dynamic quantum molecular sieving effect measurement of the 13CH4 and 12CH4 mixture on activated carbon fiber at 112 K also gave the selective adsorption of heavier 13CH4; the selective adsorptivity could be interpreted by quantum molecular dynamics. As the theoretical principle of the QMSS guarantees the more efficient separation for 14C, the present results should be a promising route of concentration and separation of 14C from the radio-graphite wastes.

Reference (1) S. Niimura, T. Fujimori, D. Minami, Y. Hattori, L. Abrams, D. R. Corbin, K. Hata, K. Kaneko, J. Amer. Chem. Soc. 134 (45), 18483—6 (2012).



138
Mott-transition type anomaly in electrical conductivity of SWCNT tiled with conjugated electron molecular systems
Fitri Khoerunnisaa, Aaron Morelos-Gomezb, Toshihiko Fujimorib, Tutomu Itohc, Katsumi Kanekob,*, et al.
a Research Center for Exotic Nanocarbons, shinshu University
b Research Center for Exotic Nanocarbons, Shinshu University
c Analytical Center, Chiba University

Confinement of substances in carbon nanospaces and presence of active edge carbon atoms have given new aspects in interface carbon chemistry. However, all carbon atoms of SWCNT are exposed to the surrounding atmosphere and thereby the even surface treatment of the SWCNT enables to change profoundly the intrinsic properties such as electrical conductivity. Polycyclic aromatic hydrocarbon (PAH)s of conjugated p-electrons interact strongly with single wall carbon nanotube (SWCNT). The morphological defects are also quite essential to govern the physical properties of SWCNT (1). Also we have a possibility of commensurate coupling of the PAH molecule with the surface carbon-hexagon structure of SWCNT and then we can design the physical properties through the relationship between the commensurate structure and physical properties. In the previous studies(2), we introduced molecular tiling method of the SWCNT walls with PAHs to modify the physical properties of WCNT.

In this presentation, we chose naphthalene derivatives of different electron donor and acceptor characteristics as the molecular tiles for coating of the SWCNT walls. We carried out the molecular tiling with liquid phase adsorption. The structure of the naphthalene derivative-tiled SWCNTs was characterized by synchrotron X-ray diffraction, high resolution transmission electron microscope, Raman spectroscopy, nitrogen adsorption at 77 K, CO2 adsorption at 283-293 K, optical absorption, and electrical conductivity measurement over the wide temperature range from 2 K to 300 K.

Naphthalene derivatives are intercalated in the interstitial sites of the SWCNT bundles to change remarkably the nanoporosity. The synchrotron X-ray diffraction and TEM supported the above-mentioned intercalation structure. The molecular tiling enhanced significantly the electrical conductivity. The electrical conductivity increased with the elevation of temperature, showing the semiconducting property. However, the electrical conductivity decreased around the room temperature, showing the metallic property. Thus, the Mott transition type anomaly was found in these naphthalene-derivatives-tiled SWCNTs.

(1) T. Fujimori, L. R. Radovic, , A. B. Silva-Tapia, M. Endo, K. Kaneko, Carbon 50, 3274-3279 (2012).

  1. F. Khoerunnisa, T. Fujimori, T. Itoh, K. Urita, T. Hayashi, H. Kanoh, T. Ohba, S. Y. Hong, Y. C. Choi, S. J. Santosa, M. Endo, K. Kaneko, dx.doi.org/10.1021/jp303630m | J. Phys. Chem. C 2012, 116, 11216−11222.



141
Performance of the carbon foams prepared form a mesophase pitch at different foaming pressures
Tong-Qi Li
Science and Technology on Advanced Functional Composites Laboratory

In order to investigate the correlation between the bulk density and the performance of the carbon foams with high thermal conductivities, different carbon foams were prepared from a mesophase pitch at 500oC by varying the foaming pressure. All the carbon foams were finally heat-treated at a temperature of 2800oC for 3h. Samples were taken out from the bottom and the top of these foams. The thermal conductivity and the compression strength were tested. It has been found that the thermal conductivity of these foams is linearly correlated with their bulk density and has no relationship with their cell structures. The compression strength is correlated not only with their bulk densities but also with their structures. The open-cell structure of the carbon foams that have low bulk densities decreases the integrality of their cell walls and consequently weakens their strength. On the contrary, the close-cell structure of the carbon foams that have high bulk densities increases their strength.



142
Comparison of Thermal Interfacial Performance of Carbon Nanofiller-Based Polymer Composites
Mohsin Ali Razaa,*, Aidan Westwoodb, Chris Stirlingc, Rafiq Ahmeda
a College of Engineering and Emerging Technologies, University of the Punjab, Lahore, Pakistan
b Institute for Materials Research, University of Leeds, UK
c Morgan Advanced Materials and Technology, Swansea, UK

Thermal interface materials (TIMs) are essential components of microelectronics as they improve interfacial contacts between the microchips and heat sinks, thus ensuring sufficient electronic cooling. Thermal interface adhesives are polymer-based composites which improve contacts between the mating surfaces, offer good thermal conductivity and also bind mating surfaces to improve mechanical integrity of the electronics packaging. High thermal conductivity and low thermal contact resistance are desirable characteristics of TIMs. Carbon nanofillers such as graphite nanoplatelets (GNP), carbon nanotubes and carbon nanofibres are being extensively researched as fillers to produce polymer composites due to their very high thermal conductivity. Carbon black (CB)-based thermal pastes have been reported to offer very low thermal contact resistances. Researchers have reported the potential of carbon nanofiller-based polymer composites for thermal interface applications due to their high thermal conductivity. However, high thermal conductivity alone cannot guarantee good TIM performance. The performance of TIMs mainly depends on wt.%, size, shape and orientation of the fillers and on the adhesion, wettability and spreadability of the resulting polymer composite dispersions, which improves thermal contacts between the mating surfaces. The present work reports comparison of thermal interfacial performance of carbon nanofiller-based polymer composite adhesives, measured according to an ASTM standard that mimics the conditions prevailing in electronics packages.

GNP/rubbery epoxy, GNP/glassy epoxy, CB/rubbery epoxy, CB/silicone and CB/GNP/rubbery epoxy hybrid composite dispersions were produced by mechanical mixing. These composites were tested as pastes (uncured matrix) and also, with cured matrix, as adhesives. The effect of GNP type, hybrid combination of CB and GNP, types of polymer matrix and CB on the thermal interfacial performance of the composites is reported. The effect of applied pressure, temperature and surface roughness of the substrate on the thermal interfacial performance of these composites is also reported. The results show that the thermal contact resistance of 25 wt.% GNP/rubbery epoxy composite is almost the same as that of an equivalent glassy epoxy composite but the former has the advantage of being applicable as thin bondlines due to its much lower viscosity. GNP/rubbery epoxy composite has lower thermal contact resistance on rough substrates than on smooth substrates. Although CB/rubbery epoxy and CB/silicone epoxy composites can be applied as thin bondlines of ~10 µm, their thermal contact resistances were significantly higher than for GNP/rubbery epoxy composites mainly due to the poor thermal conductivity of CB-based composites. The addition of GNPs into CB/rubbery epoxy composite improves the thermal interfacial performance of the CB/rubbery epoxy composites by increasing the thermal conductivity of the composite but the performance of CB/GNP/rubbery epoxy hybrid composite was inferior to GNP/rubbery epoxy composite. The thermal contact resistance of commercial 65 wt.% BN/silicone based TIM (EPM 2490) was 27 % higher than that of 25 wt.% GNP/rubbery epoxy. This comparative study suggests that GNPs offer potential as fillers for enhancing thermal interfacial performance of polymer composite adhesives and that thermal interfacial performance of adhesives depends on good combination of thermal conductivity and their interfacial contact with substrates.



143
Encapsulation of Particle Ensembles in Graphene Nanosacks as a New Route to Multifunctional Materials
Yantao Chen, Fei Guo, Yang Qiu, Edward Walsh, Robert Hurt, et al.
Brown University

A major goal in the nanosynthesis field is the fabrication of hybrid nanostructures with multiple functions for use in smart materials, biomedical diagnostics, and theranostics. Hybrid nanostructures may be designed for combinations of photonic, magnetic, radiological, mechano-responsive, catalytic, and/or targeted delivery behaviors, and the designs typically require complex multistep chemical synthesis. Recent reports of a continuous, scalable aerosol process for graphene encapsulation of nanoparticles may provide a new route to such hybrids if different types of particles can be simultaneously wrapped.

Here we demonstrate a systematic way to create multifunctional hybrid materials through aerosol-phase graphene encapsulation of ensembles of simple uni-functional nanoparticles. We first develop a general theory of aerosol encapsulation based on pH-dependent colloidal interactions in drying microdroplets. It is shown that a wide range of cargo particles can be encapsulated, including some that are colloidally unstable alone, because of association with the highly-charged, stable graphene oxide sheets. High pH is shown to be a favorable operating regime for the aerosol encapsulation process because it leads to particle/sheet electrostatic repulsion, colloidal stability, and low proton activity that limits dissolution of metal and metal-oxide nanoparticles. The cargo-filled graphene nanosacks are also shown to be open structures that rapidly release soluble salt cargoes when reintroduced into water, but can be partially sealed by filler addition during synthesis to achieve slow release profiles of interest in controlled release or theranostic applications.

Finally we demonstrate an example multifunctional material by fabricating graphene/Au/Fe3O4 and graphene/BaTiO3/Fe3O4 ternary particles as MRI/CT multimodal imaging probes. The graphene/Au/Fe3O4 probe is magnetically responsive and shows excellent MRI and CT contrast in CMC gel suspensions at low concentrations ranging from 0.05– 2000 ug/ml based on tests using full-scale clinical scanners. Graphene nanosack encapsulation is shown to be a flexible approach for the fabrication of multimodal bioimaging probes and possible theranostic devices.



144
Colloidal Phase Interactions of Graphene Oxide Sheets
Megan Creightona,*, Yuzo Ohatab, Robert Hurta, Jin Miyawakib, Arijit Bosec, et al.
a Brown University
b Kyushu University
c University of Rhode Island

Fine particles can assemble at aqueous-organic interfaces and stabilize droplets to form what is known as a Pickering emulsion. Graphene-based nanomaterials are of potential interest for this application as a replacement for chemical surfactants, because a large fraction of their atoms reside at the interface. Here we develop a thermodynamic theory for the stabilization of liquid-liquid emulsions by ultrathin platelike colloids with application to graphene materials. We show that thin plates provide higher emulsion stabilization energies than spherical particles of similar surface chemistry due to more effective coverage of the liquid-liquid interface. For atomically thin sheets such as monolayer graphene oxide, every atom lies on the interface and interacts with both liquid phases, and stabilization energies can be orders of magnitude higher than spherical nanoparticles at equal mass loading. Experiments show that GO is an effective stabilizer for a range of oil-in-water emulsions, but few-layer-graphene with pristine surfaces is much less effective. This trend is consistent with the thermodynamic theory, which provides a basis for optimizing the surface chemistry of a graphene-based material to achieve the highest stabilization free-energy. Other potential advantages of graphene-based emulsion stabilizers include tunable surface chemistry, elastic conformal coverage of curved surfaces, irreversible interface attachment, and barrier properties associated with full area coverage. The ability of graphene-based interfacial films to hinder molecular transport between the droplet and continuous phases may have application to controlled-release delivery or vaporization of functional agents in the dispersed oil phase.



147
Photo Catalytic Behavior of Carbonaceous Material Prepared from Chitin
Ishida Yuki, kawaguchi Masayuki
Osaka Electro-Communication University

Photo catalytic properties of carbonaceous materials containing nitrogen (C/N materials) were previously reported elsewhere [1]. We prepared C/N materials by pyrolysis of organic precursors and applied for capacitors [2,3]. The present paper deals with the preparation of C/N materials by pyrolysis of chitin which can be obtained from crab et al. The C/N materials were prepared by the pyrolysis of chitin which was commercially available and was made from natural crab at temperatures around 1070 K. Obtained materials were gray to black powders in color. The materials showed a structure similar to the non-crystalline carbon with the structure of calcium phosphate as an impurity. The material prepared at 1070 K decomposed methylene blue in an aqueous solution under irradiation of visible light or UV-visible light. For example, 80 % of methylene blue was decomposed by the material under the irradiation of visible light during 6 hours. In the case of using TiO2, which is the typical photo catalytic material, decomposed 79 % of methylene blue under the same condition described above. These results suggested that the C/N materials prepared in the present study showed the photo catalytic behavior comparable to that of TiO2.

Reference:[1] X. Wang, K. Maeda, A. Thomas, K. Takanabe, G. Xin, J. M. Carlsson, K. Domen, M. Antonietti, Nat. Mater, 8 (2009) 76-80. [2] M. Kawaguchi, T. Yamanaka, Y. Hayashi, H. Oda, J. Electrochem. Soc., 157 (2010) A35-A40. [3] M. Kawaguchi, A. Itoh, S. Yagi, H. Oda, J.Power Sources, 172 (2007) 481-486



148
Treatment condition of animal cellulose nanofibrils to produce graphite nanofibers
Yutaka Kaburagia,*, Ito Yutakaa, Shindo Emia, Yoshida Akiraa, Iwashita Noriob, et al.
a Faculty of Engineering, Tokyo City University
b National Institute of Advanced Industrial Science and Technology, AIST, Tsukuba

Highly crystallized cellulose nanofibrils were prepared from the outer wall of Halocynthia (tunicate). The outer wall is one of food wastes, but the cellulose is only one case prepared from animal, and so-called “animal cellulose”. The animal cellulose was purified in distilled water with 0.3% sodium chlorite at 70oC under electromagnetic stirring and then in distilled water with 5% potassium hydrochloride at room temperature. This procedure was repeated until the outer wall became pure white. The purified animal cellulose, hereafter NF-Or, is composed of pure cellulose nanofibrils with about 20 - 30 nm thick. The animal cellulose was smashed into a pulp in ethanol or t-butyl-alcohol by a liquidizer, and dispersed uniformly in each solution and then filtered, and paper like samples, NF-Et or NF-Bt, respectively, were obtained. The nanofibrils dispersed in ethanol with distilled water or dispersed in t-butyl-alcohol were freeze-dried and floss like samples, NF-Et+H2O-F or NF-Bt-F, respectively, were also obtained. These 5 samples of different treatment types were carbonized at 800oC for 30 min and then heat-treated at high temperatures up to 3100oC and kept for 30 min in high purity Ar flow. The texture and structure of the carbonized samples heat-treated at high temperatures were investigated by SEM and TEM observations and measurements of XRD and Raman spectra.

The individual carbon nanofibers were observed for the carbonized NF-Et+H2O-F and NF-Bt-F samples, even after heat-treated at high temperatures, while no individual carbon nanofibers were found for the other samples after heat-treated at high temperatures. The development of graphite structure by heat treatment was remarkable for the carbonized NF-Et+H2O-F, i. e. graphite nanofibers were obtained, and for the carbonized NF-Et with no individual graphite nanofibers, while the other samples exhibited turbostratic structure with small amount of graphitic component after heat-treated at high temperatures.

The improvement of graphite structure on nongraphitizing carbons without mechanical and catalytic treatments should be attributed to graphitization behavior on the surfaces of the nongraphitizing carbons as pointed out for carbonized bacteria cellulose nanofibrils at Carbon2012. The surface graphitization seems to have an effect not only on the surfaces of the carbon nanofibers, but also the insides because of very thin diameters. However, the graphitization effect was not effective for the carbonized samples of NF-Or and NF-Bt. The difference in graphitization behavior between the carbonized NF-Et+H2O-F and NF-Et and the carbonized NF-Or and NF-Bt should be attributed to the difference in degree of separation of the individual carbon nanofibers. If the separation is not enough, and the nanofibers stick together and make a conglomerate in some cases, graphitization occurs only on the surface region and does not progress in the inside. For carbonized NF-Bt-F, the graphitization effect was also not effective, even though the individual carbon nanofibers were observed after heat-treated at high temperatures. By the SEM observations for the carbonized NF-Bt-F, the carbon nanofibers wound considerably, and no straight nanofibers were observed. The winding texture in nanometer size of the carbonized NF-Bt-F seems to prevent improvement of graphite structure after heat-treated at high temperatures.



149
Blue photoluminescent carbon nanodots derived from coal
Chao Hu, Zhou Ying, Yang Junyu, Chang Yu, Jieshan Qiu
Carbon Research Laboratory, Liaoning Key Laboratory for Energy Materials and Chemical Engineering, State Key Lab of Fine Chemicals, Dalian University of Technology, High Tech Zone, No.2 Ling Gong Road, West Campus,Dalian 116024, China

Luminescent carbon nanodots (CDs) as a new class of carbon nanomaterials have been receiving much attention due to their chemical inertness, low toxicity, good biocompatibility, and high resistance to photobleaching. Herein, CDs were first successfully synthesized by oxidation peeling of graphite microcrystallines from coal, which is a very cheap and readily available carbon source in nature. The results preliminarily show that the coal-based CDs with a size distribution of 1~4 nm are linked by a large number of oxygen-containing functional groups, and emit blue fluorescence when being excited at ultraviolet light (365 nm). Interestingly, the photoluminescence spectra of the coal-based CDs exhibit an excitation-dependent behavior. Subsequently reduction by sodium borohydride significantly enhanced the photoluminescence of the CDs with the quantum yield of 4.2%. Their unique luminescence properties indicate their potential for use in bioimaging and varieties of optoelectronic devices.



152
Proficient photocatalytic degradation of commercial industrial dyes using CdSe-graphene and ultraviolet irradiation
Ghosh Trisha, Meng Ze-Da, Ullah Kefayat, Park Chong-Yeon, Oh Won-Chun, et al.
Department of Advanced Materials Science & Engineering, Hanseo University

This study was focused on the intriguing photocatalytic activity of CdSe-graphene composites synthesized by facile hydrothermal method, in which the composites successfully degraded highly complex commercial industrial dyes by the process of photocatalysis. Industrial dye such as Texbrite BBU- L (TBBU, liquid) and Texbrite BAC-L (TBAC, liquid) were used as sample compounds. A small reactor arrangement was organized to carry out the photocatalytic degradation of TBBU and TBAC using UV lamp (8W, VL-4.LC). The aqueous dilutions of the two industrial dyes were done forming 0.0003% V/V solution of TBBU and 0.00025% V/V solution of TBAC, owing to the slightly higher colour intensity of TBAC. The absorbance graph obtained from UV-Vis spectroscopic analysis showed the gradual decrease in the absorbance of the dyes with increasing time after the addition of the CdSe-graphene composites. The photocatalytic degradation were calculated based on the decreasing concentration as a function of increasing time obtained after the initial adsorption/desorption equilibrium. Results demonstrated CdSe-graphene composites effectively degrade TBBU and TBAC under optimum conditions.



153
Detection of oxygen species generated by CoS2 and CoS2-fullerene nanoparticle under visible light in degradation of organic dyes
Meng Ze-Da, Zhu Lei, Ghosh Trisha, Park Chong-Yeon, Oh Won-Chun, et al.
Department of Advanced Materials Science & Engineering, Hanseo University

In the present work, CoS2, and CoS2-fullerene were irradiated by visible light respectively. The generation of reactive oxygen species were detected through the oxidation reaction from 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). The composite obtained was also characterized by transmission electron microscopy (TEM) and UV-vis analysis. From the photocatalytic results, the excellent activity of the CoS2-fullerene composites for degradation of methylene blue under visible irradiation could be attributed to both the effects between photocatalysis of the supported CoS2 and charge transfer of the fullerene to enhance the photogenerated electrons transfer.



154
Lattice model of fluid dynamics in porous media: Application to Kerogen in Gas Shale
Alexandru Botana,*, Roland Pellenqb, Franz Ulmb, Benoit Coasneb
a Dept. of Civil and Env. Eng., Massachusetts Institute of Technology,USA
b Dept. of Civil and Env. Eng.;UMI 3466 CNRS-MIT, Massachusetts Institute of Technology,USA

In the context of high fuel prices the reserves of natural gas stored in shales are too large to be ignored. A major difficulty for a proper description of fluid transport in such systems stems from its multiscale texture characterized by a wide pore size distribution. Mass transfer in micropores and mesopores is very different from that in macropores and models for conventional reservoirs, intended to describing transport in macropores, are unsuitable for shale. As a result, any attempt in understanding overall transport requires a multiscale modeling approach. In this work, we built a hierarchical model of kerogen (the carbon-based matrix containing gas or oil in shale reservoir) which includes microporous, mesoporous and macroporous domains. A transmission electronic microscopy (or any imaging technique) image of kerogen obtained from experiments is divided into a grid of equal-size tiles, each of them represents subnanoporous, nanoporous, or macroporous domain.

Then fluid flow from domain i to domain j (therefore permeability of the whole sample) is described using a novel lattice model originated from the lattice gas automata method. The foundation of this lattice model will be atom-scale molecular simulations of mass transport processes. The flow behavior will be averaged to allow upscaling of length and time, and the eventual combination with continuum fluid mechanics solvers. An overview of the proposed model and comparison with Lattice Boltzmann Dynamics will be provided.



157
Production of custom-made CNT in a Riser-Reactor
Franziska Toni, Karl-Ernst Wirth
Institute of Particle Technology Erlangen

Carbon nanotubes (CNTs) are a promising additive for composite materials due to their unique properties like their high tensile strength, good electrical and thermal conductivity. Good dispersible CNTs are required to effectively transform these properties to for example a polymer matrix, since CNT need to form a percolation network. For commercial applications large amounts of reasonably priced high quality CNTs are necessary. However, CNTs fulfilling these criteria are hardly available.

Currently, the only production method that allows scale-up and therefore mass production is the catalytic chemical vapor deposition (CCVD). The production by CCVD includes flowing a carbon source over a nanometer sized metal particle, where the carbon source is cracked and the CNTs starts growing. The diameter of the CNTs is dependent on the diameter of the metal particle. A large number of processes are known for the production of CNTs by CCVD, but for scale-up the most promising ones are the gas-phase methods. In this respect solid and dissolved catalysts can be used. Solid catalyst provides less flexibility since the catalyst is produced for example by impregnation. The dissolved catalyst, also called “floating catalyst”, on the other hand, is produced in situ and therefore the catalyst size, which affects the CNT diameter, can be adjusted. The dissolved catalyst is usually composed of a carbon source e.g. ethanol and a metallocene precursor. This mixture is brought into the gas phase via a nebulizer and then carried into the reactor by a gas flow. The decomposition of the ferrocene starts at 550°C and iron clusters form which act as nucleation sites for the tubes. CNTs normally grow in between a few seconds or minutes; hence, a riser reactor is the preferred reactor since too long residence times lead to compact agglomerates. In general riser reactors are characterized by low solids concentration and short residence times. As the residence time of the catalyst particles in the riser reactor can be adjusted, the quality and the structure of the CNT agglomerates can be modified.

In literature riser reactors used for the production of CNTs represent a considerable disadvantage: the CNTs synthetized stick to the reactor wall and tend to clog the reactor or grow directly on the wall as the catalyst particles are deposited at the hot spots of the reactor. To solve these problems, a lab scale riser reactor developed at IPT is operated in a laminar flow regime to minimize the deposition of catalyst particles on the wall, thus avoiding CNT growth on the reactor wall. With this reactor CNTs of different diameters (1-25 nm) can be synthesized. To characterize this reactor, the flow regime is analyzed by particle image velocimetry (PIV) and the temperature allocation is examined by temperature measurements. Furthermore these results are compared with numerical simulations. The CNTs produced are analyzed by REM, TEM and TGA measurements. The overall goal is to derive scale-up rules to produce custom made CNTs on a large scale.



158
Broadening of C1s X-ray photoelectron spectra of carbon materials
Yasuhiro Yamada
Chiba University

X-ray photoelectron spectroscopy (XPS) is among the most powerful tools to analyze the surface structures of carbon materials, but the analysis of defects including oxygen- and nitrogen-containing functional groups is still unclear because of a large number of possible functional groups. Density functional theory calculation is one of the approaches to obtain the peak shifts of XP spectra. Due to the large number of functional groups, full width at half maximum (FWHM) of main peaks of C1s spectra should be analyzed for detailed analysis. In this work, a numerous number of oxygen- and nitrogen-containing functional groups were calculated, and FWHMs were analyzed.

Over 100 kinds of oxygen- and nitrogen-containing functional groups on edges and in the basal plane of functionalized graphene were constructed. All of the following calculation were conducted using B3LYP/6-31g(d) integral=grid=ultrafine of Gaussian 03. After optimization of structures, population analysis for simulated XP spectra was conducted. Binding energies of these model structures were directly obtained from orbital energy using an approximation based on the modified Koopmans theory applying calculation from vacuum level. For simulating XP spectra using the calculated binding energy, the number of orbitals was counted every 0.1 eV to draw spectra using Gaussian function with the full width at half maximum (FWHM) of 1.2 eV, which was obtained from the experimental FWHM of Au4f7/2.

Calculated C1s, O1s, and N1s XPS shifts of functional groups on edges and in the basal plane in this work were close to the reported values. C1s, O1s, and N1s XPS peak shifts of a number of unreported functional groups were also obtained. Among all of functional groups on edges of functionalized graphene, only a few functional groups such as hydroxyl and amino groups showed small influence on FWHMs of main peak of C1s spectra, whereas other functional groups such as semiquinone, lactone, o-quinone, and nitrile groups showed large influence. For example, FWHMs of the main peak of C1s spectra of graphene with hydroxyl groups and amino groups were both 1.2 eV, whereas those with semiquinone and nitrile were 1.4 and 1.3 eV, respectively. It indicates that FWHMs depends on functional groups on edges.

The functional groups in the basal plane such as hydroxyl and epoxy groups showed no influence on FWHMs. FWHMs of graphene with epoxy groups and OH groups in the basal plane were both 1.2 eV. On the other hand, other functional groups and vacancy defects increased FWHMs. For example, FWHMs of graphene with defects in the basal plane such as semiquinone and lactone in the basal plane increased FWHM up to 1.3 eV. FWHMs of main peaks of C1s spectra of graphene with Stone-Thrower-Wales defects, monovacancy, and divacancy defects were 1.4, 1.3, and 1.4 eV, respectively.

Functional groups such as hydroxyl and amino groups have the small influence on FWHMs of main peaks of C1s spectra in addition to the shift of the main peak of C1s spectra. Therefore, these functional groups can be utilized as reference functional groups for computational analysis.



159
Interactions between nickel ions and exfoliated graphene sheets
Yasuhiro Yamada, Yukiko Suzuki, Satoshi Sato
Chiba University

Graphene-supported metal catalysts have been studied for hydrogenation reaction, coupling reaction, and electrodes for fuel cells. The interaction between metals and functional groups of graphene becomes significant as the size of the metal on graphene becomes small. On the other hand, unstable functional groups have possibility to decompose during reaction. Our group has found that the thermal stability of nickel ion coordinated with exfoliated graphene sheets is high. However, the interaction between nickel ion and graphene sheets has not been reported in detail. In this work, the interaction of nickel ion coordinated with exfoliated graphene sheets containing both oxygen- and nitrogen-containing functional groups were analyzed experimentally and theoretically using density functional theory calculation.

Highly purified graphite powder (SP270) provided by Nippon Graphite Industries Ltd. Japan was oxidized by a Brodie method. Graphite oxide was heated in air at 1323 K for 2 min to obtain exfoliated graphene sheet (EG). EG was heated from room temperature to 573-1273 K for 30 min in ammonia gas (EG-NH). EG-NH were immersed in 2-propanol dissolving Ni(NO3)2.6H2O, and rinsed with 2-propanol using sonication. As a last step, the samples were heated in vacuum at 773 K for 30 min (EG-NH-Ni). The following calculation was conducted using B3LYP/6-31g(d) integral=grid=ultrafine of Gaussian 03. Total electron energies of optimized structures of aromatic compounds with oxygen- and nitrogen-containing functional groups were used to calculate the stabilization energy by comparing aromatic compounds with and without coordinated nickel ion.

The compositions of EG-NH and EG-NH-Ni were analyzed by elemental analysis and X-ray photoelectron spectroscopy. The amount of coordinated nickel ions was increased as the amount of nitrogen introduced in the exfoliated graphene sheets increased. Also, nickel was partially oxidized after being heated in vacuum at 773 K, probably due to the remaining oxygen on EG. It indicates that nickel ions were more stably coordinated with nitrogen-containing functional groups than oxygen-containing functional groups.

The stabilization energy of coordinating nickel ions to nitrogen- and oxygen-containing functional groups was estimated by density functional theory calculation. The stabilization energy of coordinated nickel with pyridine-like functional groups was higher than that with pyran-like and carbonyl groups. In terms of both the thermal stability and the stabilization energy, nickel ions were considered to coordinate with nitrogen-containing functional groups rather than oxygen-containing functional groups.



161
Sub-nanometer vacancy defects introduced on graphene by oxygen gas
Yasuhiro Yamada, Kazumasa Murota, Jungpil Kim, Ryo Fujita, Masashi Nakamura, et al.
Chiba University

Sub-nanometer vacancy defects in the basal plane of single-layered nano carbon materials such as graphene and carbon nanotube have been intensively studied due to a number of possible applications such as molecular sieves and coordination of metal ions as ligands. One of the methods to introduce sub-nanometer vacancy defects is a reaction between oxygen gas and the basal plane of graphene. The presence of sub-nanometer vacancy defects in the basal plane of nano carbon materials reacted with oxygen gas above 573 K has been indicated experimentally by the effect of sieving molecules and Raman spectroscopy. However, the structures of the sub-nanometer vacancy defects created in the basal plane of graphene by reacting with oxygen gas have not been directly observed.

In this work, single-layered graphene was reacted with oxygen gas at 493-573 K, and the structures of sub-nanometer vacancy defects were directly observed by high-resolution transmission electron microscope (HRTEM (TEAM 0.5)). To support the observed structures of sub-nanometer vacancy defects, X-ray photoelectron spectroscopy (XPS) and elemental analysis of highly purified graphite with high surface area of ca. 250 m2g-1 and 4 μm in diameter were conducted. Raman spectroscopy of super-growth carbon nanotubes (SGCNTs) reacted with oxygen was also conducted.

HRTEM image simulations using a graphene structure determined from density functional theory match the experimental HRTEM images indicating the reacted graphene includes oxygen-containing functional groups such as carbonyl, cyclic ether, and epoxide. The oxygen-containing functional groups on graphite treated at the same reaction conditions were also analyzed by XPS and show the presence of oxygen-containing functional groups such as carbonyl, cyclic ether, epoxide, and lactone. Lactone detected in XPS analysis was not observed in the basal plane of graphene by HRTEM probably because lactone has a low activation energy of decomposition reaction easily surpassed by the energy of an 80 keV electron beam. The oxygen contents of oxidized graphite measured by elemental analysis were increased from 0.3% to 1.3, 1.5, and 1.9% at 493 K, 533 K, and 573 K for 5 h, respectively. Assuming that all of the edges of graphite were reacted, the increase in oxygen content was calculated to be 0.014%, but it was measured to be 1.3% at 493 K, indicating that the basal plane of the graphite was reacted.

The intensity ratio of D-band/G-band of SGCNTs reacted with oxygen gas increased from 0.17 to 0.30 at 533 K for 1 week and to 0.53 at 573 K for 1 week by Raman spectroscopy, which indicates the increment of defects in the basal plane of SGCNTs. All of these results of graphite and SGCNTs can support the results that the basal plane of graphene can react with oxygen even below 573 K, specifically between 493 and 573 K.



164
Carbon nanowalls growth by surface-wave microwave plasma-enhanced chemical vapour deposition
Takashi Uchida, Yoshikazu Yoshida
Bio-Nano Electronics Research Centre, Toyo University

Carbon nanowalls (CNWs), one of the graphite-based nanostructures, have a petal-like structure, which stands perpendicular to the substrate surface. A CNW is a sheet with a length of several µm, a height of several µm, and a thickness of several tens of nm. Such sheet is composed of nanographite domains [1]. The unique structure of CNWs may have advantages for possible applications of CNWs such as field emitter, electrode, storage, coating, and so on [2-4]. CNWs have been synthesised mainly by plasma-enhanced chemical vapour deposition (PECVD) techniques. In this study, we demonstrate the synthesis of high-quality CNWs by a surface-wave microwave PECVD (SWMPECVD) and investigate the structure and the growth rate of CNWs.

A Si wafer was used as a substrate for the deposition. The deposition conditions are as follows. The chamber pressure was 20 Pa. The process gases were methane and hydrogen with their flow rates of 15 and 30 sccm, respectively. The substrate temperature was ranged from 540 to 725 oC. The deposition duration was examined up to 15 min. The frequency and power of microwave were 2.45 GHz and 350 W, respectively. The synthesised materials were characterised by scanning electron microscopy (SEM), transmission electron microscopy (TEM), micro-Raman spectroscopy, and nitrogen gas adsorption.

The synthesized materials were CNWs. The height of CNWs were analysed using SEM images. The height of CNWs was increased linearly with the deposition duration. The growth rate of CNWs in height was 1 µm/min. This is higher than the previous reports. Nonetheless the width of the G band in the Raman spectra, which is inversely related to the degree of graphitization, was small (approx. 25 cm-1). The substrate temperature did not affect the growth of the CNWs, i.e., the structure and the growth rate of them were almost the same for the different substrate temperatures. The Brunauer-Emmett-Teller (BET) surface area analysis using nitrogen gas adsorption at 77 K revealed that the CNWs has specific surface area of approx. 100 m2/g. These results indicate that the SWMPECVD technique has an advantage in terms of the growth rate or the yield of CNWs and that the CNWs are promising materials, in particular, as electrode materials.

References

1.Kobayashi K, Tanimura M, Nakai H, Yoshimura A, Yoshimura H, Kojima K, et al., Journal of Applied Physics. 2007;101(9):094306.

2.Hiramatsu M, Hori M., Carbon Nanowalls: Synthesis and Emerging Applications: Springer-Verlag 2010.

3.Tanaike O, Kitada N, Yoshimura H, Hatori H, Kojima K, Tachibana M., Solid State Ionics. 2009;180(4-5):381-5.

4.Stancu EC, Ionita MD, Vizireanu S, Stanciuc AM, Moldovan L, Dinescu G., Materials Science and Engineering B-Advanced Functional Solid-State Materials. 2010;169(1-3):119-22.



167
Large pseudocapacitance induced by redox reactions on microporous carbon in organic electrolyte
Hirotomo Nishiharaa,*, Khanin Nueangnoraja, Raúl Berenguer-Betrianb, Hiroyuki Itoia, Takashi Kyotania, et al.
a Institute of Multidisciplinary Research for Advanced Materials, Tohoku University
b Department of Chemical Engineering, School of Industrial Engineering, University of Malaga

When carbon is introduced into the nanochannels of zeolite and the zeolite is dissolved away, an ordered microporous carbon is obtained as a negative replica of the zeolite template. This zeolite-templated carbon (ZTC) has adequate electrical conductivity, together with ordered microporosity and huge surface area (ca. 3600 m2/g). One of the most important features of ZTC is a very large amount of edge sites, namely ca. 10 times larger than the amount of ordinary activated carbons. We have previously demonstrated that such edge sites of ZTC are very easily oxidized in aqueous electrolytes, and as a result, a large amount of quinone-type functional groups are introduced at the edge sites. The quinone groups give rise to large pseudocapacitance (up to 700 F/g) with reasonably high rate capability and good cyclability. On the other hand, electrochemical behavior of ZTC in organic electrolytes was investigated only in a limited potential range of –1.5 ~ 0.5 V (vs. Ag/Ag+). In this work, we report the occurrence of large pseudocapacitance of ZTC also in organic electrolytes after a proper electrochemical pretreatment simply by polarization in the same electrolyte.

A three-electrode cell including 1 M TEA-BF4/PC is constructed. An electrode sheet for working electrode is prepared by mixing ZTC, PTFE, and carbon black with the weight ratio of 90:5:5. By using the same manner, a counter electrode is also prepared, but an activated carbon fiber is used instead of ZTC. First, cyclic voltammetry (CV) is performed for 4 cycles in a potential range of –1.5 ~ 0.5 V (vs Ag/Ag+). Then, galvanostatic charge/discharge cycling (GC) is performed at several different current densities. Next, the upper potential is increased by 0.1 V (up to 0.6 V), and the set of CV and GC is repeated. Such potential expansion is then repeated up to 1.3 V. With increasing the upper potential above 0.5 V, a clear redox couple appears around 0.2 ~ 0.3 V, and the capacitance of ZTC is enhanced. The maximum capacitance of 240 F/g is achieved when the upper potential is 1.0 V. The first CV scan in this potential window (–1.5 ~ 1.0 V) shows a large anodic current above 0.7 V, indicating that ZTC is electrochemically oxidized above 0.7 V in 1 M TEA-BF4/PC. According to the results from temperature programmed desorption and FT-IR analyses, we have confirmed the increase of oxygen-functional groups in ZTC after the polarization. These results suggest that the functional groups formed during the electrochemical polarization are the origin of the pseudocapacitance. Interestingly, the capacitance of ZTC is enhanced also by widening the potential window towards negative direction. After polarization at a potential range of –2.0 ~ 1.0 V, ZTC shows new redox peaks around –1.4 ~ –0.2 V, and thus it exhibits a very high capacitance of 330 F/g.



182
Organic redox couples impregnated on carbons for high energy density supercapacitors
Suheda Isikli, Raul Diaz
Electrochemical Processes Unit, IMDEA Energy Institute, Avda. Ramon de la Sagra 3, 28935 Mostoles (Madrid), Spain

The desirable deployment of renewable energies as primary energy sources is highly dependent on the development of efficient energy storage devices with both high energy density and high power density, and carbons are the state of the art active electrode materials in many electrochemical energy storage devices due to their unique features such as high surface area, good electrical conductivity and low cost [1].

Supercapacitors are electrochemical energy storage devices which attract considerable research and commercial interests for their high power densities and long cycling life when storing energy using electrostatic forces, but they still have a relatively low energy density compared to batteries [2]. So, different strategies have been proposed in order to get energy density values closer to batteries, and the presence of pseudocapacitive reactions is a very powerful concept to overcome this issue.

In general, activated carbon surface has naturally existing functionalities which undergo Faradaic-type reactions. Quinone bearing functionalities have been confirmed as effective pseudocapacitive source thanks to their multiple and reversible electron transfer mechanism. Thus, further attempts have been done to attach these molecules onto carbon surfaces by simple and cost affordable processes.

Homogeneous reduction of diazonium salts is the mostly studied methodology for the derivatization of carbon powder with quinone type compounds. When using this method, there is a parallel physisorption process of the organic molecule which can account for up to 50% of the total molecules present on the carbon surface [2]. We have recently studied pure physisorption by impregnation of carbon with solutions of a quinone and have shown dependencies on the carbon properties and high capacitance values [3].

As impregnation is potentially a low cost alternative to reduction of diazonium salts, in the present work we demonstrate that impregnation of carbon with p-benzoquinone (p-BQ) can yield a much higher increase of capacitance values than impregnation with anthracenetetraone [3] or diazonium salt modification with anthraquinone [2]. In particular, PICACTIF BP10 activated carbon particles were impregnated with p-BQ and capacitances in aqueous 0.5 M H2SO4 were increased from 150 F/g to 400 F/g at 10 mV/s.

A complete electrochemical, structural, and physicochemical characterization including cyclic voltammetries, charge-discharge experiments including long term cycling, and physisorption experiments for measuring surface area and porosity has been carried out, allowing us to have a clear understanding of physisorption processes on carbons and their promise and future optimization possibilities for the obtention of improved carbon-based supercapacitor electrode materials with higher energy densities.

1. A. Stein et al., Adv. Mater. 2009; 21, 265-93.

2. R. D. L. Smith, P. G. Pickup, Electrochim. Acta 2009; 54, 2305-11.

3. S. Isikli, R. Diaz, J. Power Sources 2012; 206, 53-8.



185
Hydrothermal Synthesis, Solid State Transformations and Thiophene HDS Activity of Novel MoO2/Carbon Hierarchical Nano/Microcomposites.
Carlos Avendañoa,*, Alexander Briceñob, Franklin Méndeza, Joaquín Britoa, Gema Gonzálezc, et al.
a Centro de Química, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela
b Centro de Química, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela.
c Departamento de Ingeniería de Materiales y Nanotecnología, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela

Novel MoO2/C nano/microcomposites were obtained via hydrothermal carbonization of a solution of glucose and phosphomolybdic acid (H3PMo12O40). The structural characterization by FT-IR, XRPD, SEM and TEM analyses revealed the controlled formation of hierarchical MoO2/C composites with different morphologies: strawberry-like, based on carbon microspheres decorated with MoO2 nanoparticles; and MoO2/C core-shell composites. These composites can be fine-tuned by varying glucose/POM molar ratio. Subsequent transformations in the solid state through calcinations of MoO2/C core-shell composites in air lead to hollow nanostructured molybdenum trioxide microspheres together with nanorods and plate microcrystals or cauliflower-like composites (MoO2/C). In addition, the MoO2/C composite undergoes a morphology evolution to urchin-like composites when it is calcined under nitrogen atmosphere (MoO2/C-N2). The MoO2/C strawberry-like and MoO2/C-N2 composites were transformed into Mo carbide and nitride supported on carbon microspheres (Mo2C/C, MoN/C, MoN/C-N2). These phases were tested as precursors in thiophene hydrodesulphurization (HDS) at 400 °C, observing the following trend in relation to the thiophene steady-state conversion: MoN/C-N2 > MoN/C > Mo2C/C > MoO2/C-N2 > MoO2/C. According to these conversion values, it was observed a direct correlation between higher HDS activity and decreasing crystal size as estimated from the Scherrer equation. These results suggest that such composites represent interesting and promising precursors for HDS catalysts, where the activity and stability can be modified either by chemical or structural changes of the composites under different conditions.



189
Inhibition of amyloid fibrillation by the cavities of carbon nano-test-tubes
Keiji Goto, Yasuto Hosikawa, Takehiko Wada, Takashi Kyoutani
Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University

The formation of amyloid fibrils derived from amyloid β peptide (Aβ) in human brain is known as a cause of Alzheimer's disease. The fibrillation starts with the formation of self-assembled Aβ aggregate, which works as a seed crystal in biological conditions. Previously, several researchers have found the inhibition and/or destruction of amyloid fibrillation in the presence of fullerene, polymer and inorganic nanoparticles. However, the behavior of the fibrillation in nano-space such as carbon nanotubes has not yet been reported. The carbon nano-test-tubes (CNTTs) prepared by the template method using straight nanochannels of an aluminum anodic oxidized film are characterized by good water dispersibility and uniform nanochannels (φ25 nm) where water-dispersed biomolecules can be encapsulated. In this study, the encapsulation and transformation behaviors of Aβ molecules in CNTTs were investigated directly by TEM observation. The CNTTs were mixed into an Aβ-phosphate buffer solution (pH7.4) and soaked for 1~3 days. During the mixing, Aβ molecules were rapidly introduced into the cavities of CNTTs with an aggregated form. Even upon the soaking for 3 days, the morphology of the Aβ aggregates was not changed and any fibril form was not observed in the cavities of CNTTs, but slight fibrillation was witnessed in the bulk Aβ-phosphate buffer solution. In remarked contrast, without CNTTs, a significant amount of fibrils was formed in the solution within 1 day. These findings suggest that most of Aβ molecules are entrapped in the nanospace of CNTTs and, as a result, the fibrillation in the solution was inhibited due to the decrease in Aβ concentration. The thioflavin T fluorescence assay for amyloid fibril detection also supports such an inhibition effect of CNTTs on the formation of amyloid fibrils.



190
A carbon nanoring as a soft crystalline adsorbent
Hirotoshi Sakamoto, Toshihiko Fujimori, Katsumi Kaneko
Research Center for Exotic Nanocarbons, Shinshu University

We investigated adsorption properties of a carbon nanoring as a porous carbon material and elucidated its structurally soft nature induced by the uptake of guest molecules through the techniques of X-ray diffraction.

Porous carbon materials have been studied intensively for their potential for efficient storage or capture of various chemical species due to their large surface areas and pore capacities. Although reasonable design and fine tuning of the pore structures are essential for significant enhancement of the pore properties, they are more difficult to be done on porous carbons than on the crystalline counterparts. One of the reasons is that the less structural uniformity of conventional porous carbons makes it much more difficult to characterize their structures and then evaluate the pore effects thoroughly.

Cycloparaphenylenes (CPPs) are cyclic molecules with benzene rings connected at their para positions. Their structures can be seen as the shortest sidewall segments of armchair carbon nanotubes (CNTs), therefore, CPPs are also called “carbon nanorings” as a new class of nanocarbon materials. Recently, many different CPPs have been successfully prepared with complete selectivity over their ring size and chirality through sophisticated techniques of organic syntheses.

CPPs have hollow structures intrinsically, which we consider as space for guest molecules. Some structures of CPPs have been determined by X-ray crystallography, showing highly periodic packing structures. If there is a pore system in the crystal, it also would be highly uniform. These features of CPP, “the minimum unit of CNTs with a well-defined uniform structure”, are definitely valuable to investigate, because they could serve as a simple model to explain the properties of CNTs which are complicated to understand clearly.

We used [12]CPP (CPP of 12 benzene rings) for the following investigations. To evaluate the porosity of [12]CPP, nitrogen (77 K) and argon (87 K) adsorption isotherms were obtained and the isotherms exhibited almost no uptake of these molecules, which indicates that the dried structure does not have accessibility to their internal and interstitial spaces due to the low diffusivity of the molecules at each temperature.

However, when methanol and ethanol were introduced to the dried [12]CPP at 288-303 K, the isotherms showed two-step uptakes. One possible process is as follows. Because these alcohols have both hydrophilic alkyl group and hydrophilic hydroxyl group, in the lower pressure region alkyl part is favorably adsorbed on the wall of [12]CPP (1st step), and then, in the higher pressure region hydroxyl groups form a cluster-like structure through the hydrogen bonds to fill the remaining space with a lattice transformation (2nd step). The desorption isotherms exhibited large hysteresis indicating that the guest alcohol molecules are strongly bound in the [12]CPP crystal down to low pressure P/P0 = 0.03 for methanol and P/P0 = 0.007 for ethanol, respectively. It was confirmed by in situ synchrotron X-ray diffraction that the packing structures of [12]CPP also transformed corresponding to each adsorption step. The soft nature induced by molecular adsorption shown here seems to be a rare example in the field of CNTs and porous organic crystals.



191
Dispersion of nanotubes in thermoplastic polymers sheets
Ekaterina Pavlenko, Victoria Tishkova, Pascal Puech, Wolfgang Bacsa, Laetitia Dardenne, et al.
CEMES-CNRS, UPR8011, Université de Toulouse, 29 rue Jeanne Marvig, BP 94347, Toulouse, Cedex 4, France

Dispersing carbon nanotubes in a polymer matrix is a major challenge to improve the electrical and mechanical properties of carbon nanotubes polymer composites. We have recently discovered that carbon nanotubes (CNT) disperse spontaneously in Poly Ether Ether Ketone (PEEK) when annealing 1. PEEK is a high performance polymer, chemically inert and has a high thermal resistance satisfying the temperature range requirements for aircrafts. The high melting temperature (343°C) and strong adhesion of PEEK are challenging when making composites.

To study this dispersion, we have used solutions of CNTs in NMP (N-methyl-2-Pyrrolidone) which were stable after sonication (at least for several hours) and which could wet well the PEEK surface. A solution with a known concentration can be prepared using nanotubes with different number of walls. CNTs deposited on PEEK surfaces show a much higher electrical resistance before annealing at the temperature of 380°C than after. This observation of resistance reduction with annealing that is also correlated with the amount of deposited CNTs shows indirectly the effect of tube dispersion on electrical resistance. We optimize the annealing time, annealing temperature and the quantity of CNTs used.

Several techniques have been used to characterize the surface with deposited CNTs. We investigated the effect of the annealing on the dispersion and electrical conductivity. While transmission electron microscopy turns out to be limited when observing small diameter nanotubes in a polymer matrix, Raman spectroscopy can be used to monitor the tube dispersion at different scales (> 1 micrometer). The charge transfer from the PEEK to CNTs and the crystallinity of PEEK can be analyzed using Raman mapping through images and histograms.

1 1. V. Tishkova, G. Bonnet, P. Puech, W. Bacsa, Uniform dispersion of nanotubes in polymers through thermal diffusion, Carbon 10.1016/j.carbon.2012.10.033



192
Competitive uptake of SO2 and CO2 from air by porous carbon containing CaO and MgO
Adam Czyzewskia, Joanna Kapicaa, Robert Pietrzakb, Antoni W. Morawskia, Jacek Przepiórskia,*
a West Pomeranian University of Technology in Szczecin, Poland
b Adam Mickiewicz University in Poznan, Poland

Porous carbon containing CaO and MgO, prepared by one-step carbonization of poly(ethylene terephthalate) mixed with a natural dolomite, was examined as a sorbent material for simultaneous removal of CO2 and SO2 from air in dry conditions and in a presence of humidity. Attained results clearly confirmed crucial effect of water on the uptake of the gases and on mechanisms their removal from air streams. As confirmed by XPS studies, in dry conditions minor amounts of the gases were removed mainly due to chemisorption on the metal oxides. During removal of either CO2 or SO2 in presence of water, the MgO/CaO – containing carbon material performed much more efficiently than in dry conditions. Formation of either CaCO3 or Ca3(SO3)2SO4 and MgSO4, was confirmed, respectively.

While both contaminants were simultaneously removed from air in humid conditions, formation of CaCO3 was favored. As a consequence uptake of CO2 by the sorbent material increased while amounts of SO2 captured tended to lower with humidity content in the system. Regardless of conditions used for simultaneous removal of CO2 and SO2, the latter always displaced certain amounts of CO2 initially retained by the bed. Amounts of CO2 displaced and thus uptakes of the gas by the sorbent material appeared to be especially impacted by humidity content and to less extent by temperature used during breakthhrough tests. Amounts of CO2 displaced slightly increased with temperature and considerably decreased with humidity content. XPS, XRD and TG-MS studies confirmed that uptake of both contaminants was predominantly due to chemical interaction with CaO. On the other hand, only partial transformation of MgO was confirmed.



193
Raman D band behavior for pyrocarbons with crystallite size ranging from 2 to 5 nm
Philippe Mallet-Ladeiraa, Pascal Puecha,*, Patrick Weisbeckerb, Gerard Vignolesb, Marc Monthiouxa
a CEMES-CNRS, UPR8011, Université de Toulouse, 29 rue Jeanne Marvig, BP 94347, Toulouse, Cedex 4, France
b Université Bordeaux 1, CNRS, Laboratoire des Composites ThermoStructuraux, UMR 5801, 3 Allée de la Boëtie, F33600 Pessac, France

Raman spectroscopy is a versatile tool to characterize defective carbon. Since the work of Tuinstra and Koenig [J. Chem. Phys. 53, 1126, 1970], the ratio of intensities between the D and the G band has been widely used. With the understanding of the 2D band (previously called G’), other indicators have been tentatively proposed but not retained. With the rise of graphene, well controlled amounts of defects have been introduced and observed experimentally leading Lucchese et al [Carbon 48, 1592, 2010] to consider two domains around a defect with an extension of the lattice region electronically impacted by the presence of a defect of about 2 nm. The length travelled by the electron associated to the D band is in the range of few nanometers. Beams et al [Nanoletters11, 1177 2011] have developed a novel optical defocusing method for studying spatial coherence of photoexcited electrons and found a typical length of 3 nm. Previously, from the uncertainty principle, Casiraghi et al [Nano Lett9, 1433, 2009] have proposed a value of 4 nm. Consequently, with a domain size lower than this value, multi-scattering events should be considered and it is not surprising to find a new behavior or new effects.

Pyrocarbon are examples of disordered graphene-based carbons whose crystallite size La ranges from 2 to 5 nm ideal for this purpose. Using several wavelengths, we clearly show that the D band should be fitted with two contributions. Other approaches with several bands added until the spectrum is well fitted are not satisfactory at all from a physical point of view and cannot resist to an analysis of their wavelength dependences. The La range size is between two different Raman behaviors, one for which the D band broadens (for La < 2 nm) and the other for which the D band sharpens (for La > 5 nm) respectively, with increasing La. We demonstrated that the Raman spectrum is well fitted with simply two Lorentzians with various respective contributions centered at the wavenumber of the D band and a Breit-Wigner-Fano shape for the G band (giving a shape approaching well the phonon density of states). Each intensity contribution for the D band varies linearly with La between 2 and 5 nm while the total D band intensity is nearly constant for excitation wavelengths ranging from 0.532 to 0.638 µm. On the contrary, the integrated intensity ratio D/G follows the well-known 1/La law.



194
Charge transfer between carbon nanotubes and sulfuric acid or potassium using Raman spectroscopy
Pascal Puecha,*, Yu Wangb, Ekaterina Pavlenkoa, Victoria Tishkovaa, Wolfgang Bacsaa, et al.
a CEMES, UPR 8011, CNRS-Université de Toulouse, 29, rue Jeanne Marvig, BP 94347, 31055 Toulouse, France
b CRPP, UPR 8641, CNRS-Université Bordeaux I, 115 Avenue Schweitzer, 33600 Pessac, France

Determining accurately the charge transfer by an optical way is fundamental to go further in the interpretation of chemical experiments. The spontaneous interaction between sulfuric acid and double walled carbon nanotubes is studied using Raman spectroscopy [1]. We have also acquired Raman spectra on double walled carbon nanotubes intercalated with potassium. These two materials allow analyzing several behaviors with strong p and n doping. The large amount of Raman data available from the literature and from our measurements using wavelengths ranging from UV to infrared allows addressing the quenching of the optical transition, the Raman shift and the electron-phonon coupling. While sulfuric acid bath can be performed in air, intercalation of potassium has to be done in inert atmosphere. The interaction of sulfuric acid with carbon nanotubes is easier to observe experimentally as the quenching of the optical transition is lower than 2 eV and the phonon shape for the outer tube remains Lorentzian. With potassium, the displacement of the Fermi level is expected to be in this range and we observe a modification of the G band shape and position.

With sulfuric acid, we are able to determine the charge transfer without any additional parameter using the spectral signature of inner and outer walls of double wall carbon nanotubes. While both the lattice contraction and the non-adiabatic effects contribute to the phonon shift for the outer wall, only the lattice contraction contributes for the inner nanotube. For the outer nanotube, we are able to separate these two contributions of the Raman G band shift as a function of the charge transfer. The linear law (wavenumber shift versus the charge transfer fc) usually used corresponds only to the lattice contraction and cannot be used with the spontaneous interaction of carbon nanotubes with a dopant. A more careful analysis shows that an additional term which depends on the dopant should be added to the linear term in fc.

Graphite intercalated compound (GIC), which is equivalent to graphene in contact with dopant, is an ideal system giving enough insights to fully interpret the data. Studies dealing with GIC indicate a charge transfer limit. This limit value is interesting to analyze the results with carbon nanotubes and check the consistency of the findings.

[1] “Charge transfer between carbon nanotubes and sulfuric acid as determined by Raman spectroscopy” , Pascal Puech, Tao Hu, Andrei Sapelkin, Iann Gerber, Victoria Tishkova, Ekaterina Pavlenko, Benjamin Levine, Emmanuel Flahaut, and Wolfgang Bacsa, Phys. Rev. B 85, 205412 (2012)



195
Natural and anthropogenic sources of carbons materials: coal, coal mining residues, and coal combustion residues
Joana Ribeiroa,*, Jordi Piellab, Sandra Rodriguesa, Victor Puntesb, Deolinda Floresa
a Centre of Geology from University of Porto. Rua do Campo Alegre, 687. 4169-007 Porto, Portugal.
b Catalan Institute of Nanotechnology, Autonomous University of Barcelona Campus, 08193 Bellaterra, Spain.

Carbon-containing particles from coal and its combustion by-products are a topic of expanding scientific interest, and significant research is required due to the ability of carbon materials to be used in a variety of different areas such as nanotechnology. In addition, most attention should also be dedicated to environmental and health implications related with the emission of C-containing ultrafine and nanoparticles from fossil fuels combustion. Carbon nanotubes, fullerenes, other C-containing nanoparticles and nanominerals have been detected in various geological materials, including coal combustion by-products.

The main goal of the present study is to identify and characterize carbon materials present in coal, coal mining residues, and coal combustion residues. For this study, samples of coal (anthracite type) from Douro Coalfield (NW Portugal), the mining residues resulting from the past coal mining activities (since 1795 until 1994) and the fly ash produced by coal combustion for power generation in a thermal power plant were analyzed. Some samples of coal mining residues were collected in coal waste piles which are under self-burning process since 2005, when intense forest fires caused their ignition. In this case, these samples are considered to be the result of natural and uncontrolled combustion whereas the fly ash samples are the result of industrial and controlled combustion process.

Transmission electron microscope (TEM) and high resolution transmission electron microscope (HR-TEM) with energy-dispersive x-ray spectroscopy (EDX) detector were used for the identification and characterization (size, shape, morphology, microstructure, chemical composition and crystallinity) of the carbon fraction present in coal, coal waste material, and fly ash. The samples were also analyzed with dynamic light scattering (DLS) to determine the ultrafine and nanoparticles size distribution. For TEM, HR-TEM and DLS analyses the samples were firstly powdered, suspended in water, and then, for TEM and HR-TEM observations, the samples were prepared by drop casting the solutions on cupper grids coated with amorphous carbon ultrathin films and left to dry at room temperature.

The TEM and HR-TEM/EDX observations and analyses demonstrated that the coal, coal waste material, and fly ash presented a wide variety of carbon constituents with different aspects, structure, and size. In coal were observed spherical nanoparticles with C in the core and Si on the outer side. These particles tend to appear in smaller quantity, or even disappeared, in the burning coal waste and fly ash samples, which is attributed to the combustion process that may have caused their thermal transformation. In samples resulting from self-combustion process in coal waste piles it was observed graphite particles. Previous studies demonstrated that the combustion of these materials could have reached 1500ºC, based on the identification of neoformed mineral phases. In addition, it is also scientifically accepted that at this temperature the graphitization of anthracites takes place, at least partially. The DLS is a well-known tool to determine the hydrodynamic diameter of particles in suspension. The results demonstrated that the samples present a heterogeneous size distribution, having carbon particles from 2 nm up to particles in the µm range.



198
Metal-free carbon nanotubes as catalysts for advanced oxidation processes: the role of surface chemistry
Raquel Rocha, João Restivo, Adrián Silva, Manuel Fernando Pereira, José Luís Figueiredo, et al.
Laboratory of Catalysis and Materials - Associate Laboratory LSRE/LCM, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal

Carbon materials are recognized as efficient catalysts for degradation of small chain carboxylic acids by advanced oxidation processes (AOPs), such as catalytic wet air oxidation and catalytic ozonation [1]. Recent works using metal-free carbon nanotubes (CNTs) as catalysts for both processes [2, 3] have shown that the performance of CNTs depends on their texture and surface chemistry, which can be tuned by adequate treatment methods.

In this work, commercial multiwalled carbon nanotubes (CNTs) were subjected to different liquid-phase treatments with nitric acid, sulphuric acid, mixture of both acids, and urea, in some cases followed by gas-phase thermal treatments in order to incorporate different types and amounts of oxygen containing groups on the surface of the CNTs. During the performed treatments, several surface groups were incorporated on the CNTs structures, including carboxylic acids, anhydrides, phenol and sulfonic groups as well as nitrogen functional groups, which were determined by suitable methods, such as temperature programmed desorption and X-ray photoelectron spectroscopy. The point of zero charge was used to characterize the acidity of the samples, and nitrogen adsorption isotherms were used to evaluate the modifications on the textural properties introduced by the applied treatments.

The catalytic performances of the pristine and modified CNTs were evaluated in two AOPs (catalytic wet air oxidation and ozonation) using two organic model compounds, namely oxalic acid and phenol. The nature of the oxygen-containing groups incorporated during the chemical treatments has a significant influence on the catalytic activity of the materials for the oxidation of both model pollutants, regardless of the oxidation process tested. The presence of the oxygenated surface groups incorporated during the nitric acid treatment was perceived as less favourable than sulfonic groups resulting from the sulphuric acid treatment. However, the presence of N-containing groups (in the urea-treated samples) additionally contributed to the higher catalytic activity of those materials.

Acknowledgments

This work was supported by projects: FREECATS financed by the European Union 7th FP (2007-2013), grant no. 280658; PEst-C/EQB/LA0020/2011, financed by FEDER through COMPETE - Programa Operacional Factores de Competitividade and by FCT - Fundação para a Ciência e a Tecnologia; and NORTE-01-0162-FEDER-000051 (SAIECT-IEC/2/2010). S.M.M.R. acknowledges the research fellowship PT/2012/17 (IAESTE programme).

References

  1. Serp P, Figueiredo JL (Eds.). Carbon Materials for Catalysis. Wiley, Hoboken, 2009.
  2. Rocha RP, Sousa JPS, Silva AMT, Pereira MFR, Figueiredo JL, Appl. Catal. B: Environmental 2011; 104:330-336.
  3. Gonçalves AG, Figueiredo JL, Órfão JJM, Pereira MFR. Carbon 2010; 48:4369–4381.


199
Synthesis and Characterization of Multi-Walled Carbon Nanotubes by Spray Pyrolysis using Tire Pyrolysis Oil as Starting Material
Srinivasan Karthikeyana,*, Mani Karthikb, Abdul Cafoor Jafar Ahamedc, Dhandapani Saravanand, Chinnusamy Sathiskumara, et al.
a Department of Chemistry, Chikkanna Government Arts College, Tirupur, TN, India
b CIC Energigune, Energy Cooperative Research Centre, Parque Tecnológico , Spain
c Department of Chemistry, Jamal Mohamed College, Tiruchirappalli. TN, India
d Department of Chemistry, National College, Tiruchirappalli. TN, India

Tire pyrolysis oil (TPO) from recycling of waste tires has been found to be effective precursor for the synthesis of one dimensional carbon nano materials. Multi-walled carbon nanotubes (MWNTs) have been successfully synthesized by spray pyrolysis using Tire pyrolysis oil and ferrocene mixture on silicon substrate at 850 ºC under argon atmosphere. Ferrocene was used as a source of Fe which acts as a catalyst for the growth of MWNTs. As-grown MWNTs was characterized by scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM) and raman spectroscopic studies. Raman spectroscopy demonstrated the presence of well graphitized MWNTs. This regenerative and low-cost material may be effective starting material for scalable mass production of MWNTs. Photovoltaic characteristic of MWNTs from TPO were also reported.

Key words: Tire pyrolysis oil; Multi-walled Carbon Nanotubes; Ferrocene; Spray Pyrolysis;



200
Application of novel mesophase pitch-based carbon-fiber web as the negative electrode in lithium-ion batteries
Takahiro Kitanoa, Fujio Okinob,*
a Hiramatsu Sangyo Co.
b Faculty of Textile Science and Technology, Shinshu University

Electrochemical performances of the novel mesophase pitch-based carbon-fiber web as anode materials in lithium-ion batteries were investigated.

The web was prepared using an aqueous solution of polyvinyl alcohol without organic solvents. The dispersion of mesophase pitch in polyvinyl alcohol (PVA) water solution was electrospun to form a web of nanofibers. The web was heat-treated at 2800 °C in argon. The diameters of carbon fibers were 200 to 800 nm. The XRD peak near 2θ = 26°, which corresponds to the (002) diffraction of graphite, was broad and at slightly lower angle compared to that of the graphite powder because of the less crystalline nature and the smaller size of the mesophase pitch-derived graphitic particles. The TEM observation indicated that the fiber consists of the aggregates of mesophase pitch-derived small graphitic particles surrounded by an amorphous substance likely originating from PVA.

Electrically conductive web-based electrodes were fabricated without copper current collector and binder, which will lead to more compact and economical LIBs. The reversible capacity for the graphite powder used for comparison was larger than that for the web at lower rates (50-100 mA/g), but the capacity for the web was lager than that for the graphite powder at higher rates (100-3000 mA/g). The results are partially attributable to the difference in their specific surface areas. The capacity and the rate performance at higher rates of the mesophase pitch-based carbon-fiber web improved when the web was pulverized due to an added increase of the specific surface area.

Application of the novel mesophase pitch-based carbon-fibers as conductive additives in cathode of lithium ion batteries will also reported.



201
Preparation and Characterization of Si/C Anode Materials for LIB via Dip-coating of Resol Resin on the Surface of Si/PVA Electrospun Nanofibers
Ding Nan, Zheng-Hong Huang, et al.
School of Materials Science and Engineering

Silicon is an exciting and promising alternative anode material in Li-ion batteries due to its high gravimetric capacity of ~4200 mAh/g, high volume capacity of ~ 9786 mAh/cm3, relatively low working potential (~0.5 V vs Li/Li+), abundance and environmentally benignity. However, there are some significant challenges such as pulverization of the silicon caused by up to 400% large volume changes, unstable solid-electrolyte interphase (SEI) formation during the electrochemical cycles, poor electrical conductivity, etc. In this work, we demonstrate a kind of hollow carbon nanofibers containing silicon nanoparticles which were prepared by dip-coating of resol resin on the surface of Si/PVA electrospun nanofibers and subsequent thermal treatments. The nanofibers exhibit relatively good electrochemical properties when used as anode materials. It suggests a new, low-cost and scalable synthetic method for lithium battery anodes suffering from volume expansion.



202
Copper cyanocomplexes adsorption on activated carbon from different source materials: Mechanisms and effects on gold adsorption
Clauson Souza, Virginia Ciminelli, Daniel Majuste, Heitor Abreu
UFMG

An adsorption mechanism of copper cyanocomplexes on activated carbon based on the nature of the interaction among the negatively charged copper species and the available reactive sites of the adsorbent material is proposed. The mechanism takes into account the effects of pH, CN/Cu molar ratio, and ionic strength not only on copper adsorption density, but also on the physicochemical properties of the activated carbon (e.g., density of surface functional groups - DSFG - and point of zero charge - PZC). The solid samples were also characterized in this work by the specific surface area (SSA) and ash content (A). The DSFG value of each sample, as well as the identification of the functional groups, was determined by the Boehm method, while the PZC value was obtained by titration. The results demonstrated an enhanced interaction of copper species under acidic conditions (i.e., pH < PZC) and low ionic strength, which may be explained by a net positive charge on the surface of the solid phase. Under alkaline conditions (i.e., pH > PZC) and low ionic strength, the interaction is less favorable. The net charge is negative under this condition, but positive charges due to the presence of remaining protonated basic functional groups may still be available. On the other hand, when such basic groups are completely deprotonated, a more intense electrostatic repulsion of the negatively charged copper species takes place, thereby decreasing metal adsorption. Under typical, industrial conditions (i.e., pH > PZC and high ionic strength), the surface of the activated carbon interacts with cations present in the solution in a way that the attraction of the negatively charged species is favored. The interaction of Ca2+ ions, for instance, with acid functional groups of the activated carbon may generate an excess of locally positive charges on the surface of this material, enhancing copper adsorption. This finding was supported by DFT calculations. In a subsequent investigation, the effects of the properties of the substrate and process parameters such as excess of cyanide, addition of calcium ion, and aeration, on the selective adsorption of gold were evaluated. Samples with the lowest density of surface groups were found to be more selective to gold adsorption. This finding was also supported by DFT calculations. Finally, the results obtained in this work may be helpful to minimize the effects of copper adsorption on activated carbon during gold recovery, thereby favoring the treatment of low-grade, complexes gold resources, an upcoming trend.



203
Carbon & Graphite for Energy Storage Technologies - An Overview
Oswin Öttinger
SGL Carbon GmbH, Werner-von-Siemens-Str. 18, 86405 Meitingen, Germany

The ongoing industrial development and the growth in population will boost the worldwide energy demand over the next decades. Besides energy generation based on fossil fuels such as oil, gas and coal the energy generation based on renewable sources like wind and solar combined with a set of advanced energy storage technologies will play a significant role in the future. For most of these electrical energy storage technologies such as supercapacitors (EDLC), various batteries like lithium ion batteries (LIB), redox flow or sodium sulfur batteries and fuel cells the key element of choice is carbon.

The double digit growth in LIB and EDLC will cause additional demand for engineered carbon and graphite powders. The expansion of LIB and EDLC applications from electronic and consumer area to the area of electro-mobility generates new technological and economical challenges. Higher cycling stability, longer lifetime, higher storage capacity, quick charging behavior, higher safety at lower cost are just some of the key challenges of graphite and amorphous carbon based anode material solutions for LIB. In case of carbon powders for EDLC application the comprehensive understanding of the porous structure as well as the volumetric capacitance is gaining more and more importance.

Redox flow and sodium sulfur batteries for stationary energy storage will require advanced carbon fiber based felts. In addition to electrical conductivity, the permeability properties and the surface chemistry will determine the efficiency and last but not least the breakthrough of these large-scale electrical storage devices. Besides carbon felt materials redox flow batteries call for economical graphite based bipolar plates with high chemical stability and low electrical resistivity.

Looking at low and high temperature proton exchange membrane fuel cells (PEM-FC) the carbon fiber based gas diffusion layers with a system specific carbon based micro-porous layer in fuel cell stack is often underestimated. Besides small commercial fuel cell series for applications such as backup power systems and forklifts the fuel cell is at the beginning of an extended field testing for stationary and for automotive applications worldwide. Stable, long lasting constant performance, higher current densities with an adequate water management at lower cost are the main challenges.

All things considered, the variety of carbon has a sustainable future in the field of storage technologies for renewable energies. Therefore, we believe that “More Carbon for less CO2” is the answer to our prosperous common future.



204
Influence of production parameters on structural properties of carbon nanospheres produced from complex hydrocarbon residues
Alexandre Castro, Luiz Castro
Centro Tecnológico do Exército

Carbon nanospheres have been produced from a variety of carbon-rich precursors, including pure hydrocarbons, polymers and heavy petroleum residues, aiming at potential applications in composites, catalysis and electrochemistry, among others. In this work, the effect of temperature, carrier gas flow rate and precursor feed rate on the structural features of nanospheres produced from four residues of different industrial origins was studied. Nanosphere production was carried in a continuous process setup using a vertical furnace and nitrogen as carrier gas, as cost reduction is a fundamental issue for the application of this kind of material. Structural parameters determined included sphere morphology by SEM, diameter distribution and aggregation by centrifugal sedimentation and thermal stability by oxidative TGA.



206
Activated carbon fiber as redox mediator for the anaerobic reduction of methyl red
E. Emilia Ríos-Del Toro, L. B. Celis, Francisco J. Cervantes, J. René Rangel-Méndez
Instituto Potosino de Investigación Científica y Tecnológica (IPICYT)

These results are the first evidence of the role of activated carbon fiber (ACF) as redox mediator in the reductive decolorization of methyl red. Also biofilm formation on ACF and its implication in redox-mediating capacity of ACF was evaluated. ACF was chemically modified with HNO3 by 0.5, 1, 1.5 and 2 h. Chemical modification of ACF increased up to 3-fold its redox-mediating capacity during methyl red reduction in chemical assays, while biological tests reported an increase of 8-fold, compared to controls incubated without ACF. However, reduction rate of methyl red without biofilm was 8-fold greater. Thus, biofilm formation on the ACF decreased its redox-mediating capacity. Further kinetic studies suggested that the electron transport from ACF to methyl red, was the rate-limiting step in the process. Due to the versatile characteristics of ACF and its redox-mediating capacity, it could be applied in wastewater treatment systems to accelerate the reductive transformation of pollutants commonly found in industrial effluents.

Key words: activated carbon fibers, biofilm, decolorization, methyl red, and redox mediator.

References

  1. Van der Zee, F. P., Bisschops, I. A., Lettinga, G. y Field, J. A. (2003). Environ Sci Technol 37, 402-408.
  2. Pereira, L., Pereira, R., Pereira, M.F.R., van der Zee, F.P., Cervantes, F. J. y Alves, M. M. (2010). J Hazard Mater 183, 931-939.


207
Characterization of a Zeolite-templated carbon by electrochemical quartz crystal microbalance
Dolores Lozano-Castellóa,*, S. Leyva-Garcíaa, K. Nueangnorajb, H. Nishiharab, T. Kyotanib, et al.
a Departamento de Química Inorgánica e Instituto Universitario de Materiales. Universidad de Alicante.
b Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan

Zeolite-templated carbon (ZTC) synthesized in the nanochannels of zeolite Y is a promising candidate as electrode for electric double-layer capacitors (EDLC), because of the high surface area (as high as 4000 m2/g [1]), the pore diameter, the regularity of the pore arrangement and the three dimensional penetration of the ordered pores [2, 3]. Recently, it has been observed that ZTC can be electrochemically oxidized, resulting in a high increase of the specific capacitance due to the contribution of the pseudocapacitance, and capacitance values over 700 F/g have been reported in 1M H2SO4 solution [4].

The objective of the present work is to use the electrochemical quartz crystal microbalance (EQCM) to analyze the mass change produced during the electrochemical characterization of the ZTC. The electrochemical and gravimetric behaviour under different potential ranges have been analyzed in order to study the changes occurring in the ZTC during the change in potential.

Electrochemical oxidation of the ZTC has been analyzed by the EQCM. More than 20 scans have been done using two different subsequent intervals (from -0.10 to 0.80 V and from -0.10 to 1.20 V vs Ag/AgCl (KCl sat)). For both scan intervals, a large mass increase is observed in the first cycles due to the electrochemical oxidation of the carbon, and after several cycles, the mass change is negligible reaching a steady state.

References

[1]Matsuoka K, Yamagishi Y, Yamazaki T, Setoyama N, Tomita A, Kyotani T. Carbon 2005;43:855-94.

[2]Ma Z, Kyotani T, Tomita A. Carbon 2002;40:2367-74.

[3]Nishihara H, Itoi H, Kogure T, Hou PX, Touhara H, Okino F, Kyotani T. Chemistry A European Journal 2009;15:5355-63.

[4]Berenguer E, Nishihara H, Itoi H, Ishii T, Morallón E, Cazorla-Amorós D, Kyotani T. The Annual World Conference on Carbon; 2012; 17-22 June; Krakow, Poland.



208
Carbonization behavior of fibers from solvent-soluble aromatic polymers
Toshihira Irisawa, Yasushi Soneda, Masaya Kodama, Hiroaki Hatori
National Institute of Advanced Industrial Science and Technology (AIST)

Over 90% of carbon fibers are commercially produced from polyacrylonitrile (PAN) and mesophase pitch precursors. In order to render the precursor fibers infusible, a preliminary thermal oxidation process at low temperatures (about 200 - 400 oC) is required prior to carbonization. It is known that a considerable amount of heat evolution at this preliminary oxidation step should be strictly controlled , and hence the process is extremely lengthy.

Some aromatic polymer having rigid-rod structure can be carbonized without a preliminary oxidation step due to the highly heat-resistant nature., and the polymers are attractive material as the precursor of highly oriented carbon fibers. This study reports here the carbon fiber production from the new precursors. Poly[bis(benzimidazobenzisoquinolinone)] (PBB) and polybenzimidazole (PBI) fibers were chosen as precursors,whichare solvent-soluble aromatic polymers and have high carbon content. The carbonization behavior of PBB and PBI fibers was investigated by using wide- and small- angle X-ray scattering (WAXD, SAXS), scanning electron microscopy (SEM) and measurements of density and mass changes. The measured parameters were compared with PAN-, pitch- and some aromatic-polymer-based carbon fibers.

PBB was synthesized from 4,4’-binaphthyl -1,1’8,8’-tetracarboxylic acid and 4,4’-biphenyl-1,1’,2,2’-tetraamine (BPTA). PBI was synthesized from terephthalic acid and BPTA. These polymers were dissolved with methanesulfonic acid and were spun to fibers by wet spinning. These fibers were heat-treated at desired temperatures in nitrogen atmosphere.

PBB and PBI fibers could be carbonized without melting, maintaining fiber geometry, and PBB- and PBI -based carbon fibers were obtained in high carbonization yield of 77.3 and 65.6 % after heat-treatment at 1500 oC. It is known that the density of PAN-based carbon fiber changes just over and below 1.7 g cm-3 by balance relations of the amount of void and a degree of graphitization in the heat-treatment temperature region from 1000 to 1500 oC. On the other hand, the density of PBB- and PBI -based carbon fibers had a steady value mostly with 1.8 g cm-3 and 1.7 g cm-3 in the same heat-treatment temperature range.

By heat-treatment at 1500 oC, the cross section of PBB-based carbon fibers showed lamellar stacking structure like high modulus carbon fibers in the SEM photographs, while crystallite parameters such as Lc, La and d002 from WAXD profiles are similar to PAN-based carbon fibers. Furthermore, it is expected from SAXS profiles that the microvoids in PBB- and PBI based carbon fibers were of needle-like shape, oriented in the fiber axis direction.



209
Production of nanoscopic particles through the hydrothermal carbonization of E. grandis wood
Jorge De Vivo, Nestor Tancredi
Laboratorio de Fisicoquímica de Superficies, DETEMA, Facultad de Química, Universidad de la República

The hydrothermal carbonization (HTC) of E. grandis wood was carried out at 200 ºC, after a previous treatment with concentrated sulphuric acid at room temperature, yielding nanoscopic particles. These exhibit a morphology which significantly differs from that of the particulates obtained through the HTC of E. grandis without a previous hydrolysis, consisting now of larger particles covered with much smaller (roughly 30 nm in size) particles. The products were characterized through different methods, including SEM, FTIR and nitrogen adsorption.



210
Control of the pore structure of pillared carbons
Yoshiaki Matsuo, Shogo Akita
University of Hyogo

We have recently reported the preparation of pillared carbons with soft pores from the pyrolysis of graphite oxide silylated with methyltrichlorosilane repaetedly [1]. Microporous pillared carbos are usually obtained and it was rather difficutl to control the pore strucuture in them even if we use various silylating reagents for the precursors of pillars. In this study, graphite oxide was first reacted with hydradine in order to reduce the number of oxygen containing groups where silylating reagnets are attached. It is expected that the distance between pillars increase and the larger pores are formed in pilalred carbons by using the reulting reduced graphite oxides as starting materials.

Graphite oxide (heareafter GO) was preapred based on the Brodie’s method. The reduction of it was perfomerd in 0.1M ammonia soultion using variuos amounts of hydradine monhydrate as a reducing reagent. The reduced GO was silylated with octyltrichlorosilane and then with methyltrochlorosilane 3 times according to our previous paper [1]. The resulting silylated graphite oxide was heated at 500°C under vacuum.

The diffraction peak observed for the prestine GO at 2θ=13° gradually shifted to higher angles with the increase in the amount of added hydradine and reached 2θ=24°, indicating that the oxygen functional groups were removed from the layers of GO. When the resulting samples were silylated, the diffraction peak shited to lower angles. The interlayer spacings of the silylated samples were smaller than that observed for the prestine GO silylated in the same manner and the silicon content in them decreased with the increase in the amount of added hydradine. When the sample with lower silicon contents were heated, the diffraction peak at 2θ=8° was observed, indicating that the pillared carbons with an interlayer spacing of 1.1 nm were formed. This value was slightly smaller than that of pillared carbon preapred from prestine GO (1.3 nm). The N2 adsorption isotherm of these pillared carbons were type IV and BET surface area decreased to 332 m2/g. These indicate that the reduction of oxygen containing functional groups on GO layers resulted in the increase of the pore size in the resulting pillared carbons.

Reference

[1] Y. Matsuo, K. Konishi, Chem. Commun., 47, 4409-4411 (2011).



211
Preparation of enzymatic biofuel-cell electrodes from a carbon-coated alumina film with straight nanochannels
Yasuto Hoshikawaa,*, Alberto Castro-Muñiza, Hiroshi Komiyamaa, Takashi Kyotania, Tetsuji Itohb, et al.
a Institute of Multidisciplinary Research for Advanced (IMRAM), Tohoku University
b National Institute of Advanced Industrial Science and Technology (AIST)

An enzymatic biofuel cell has attracted a lot of attention since they are green and safe power sources and can be miniaturized for the use of energy suppliers of implantable electronic medical devices. The amount of enzyme immobilized in the electrode directly affects the performance of the biofuel cell. In order to load a larger amount of enzymes, a porous collector with high surface area such as carbon black has been utilized so far. On the other hand, the electrode efficiency depends also on the diffusion of reactants and products in the electrode; e.g., the performance of an electrode with irregular pore structure such as carbon black might be limited. An anodic aluminum oxide (AAO) film, which possesses an array of parallel and straight nanochannels with a uniform diameter, can be fully and uniformly coated with a thin carbon layer by pyrolytic carbon deposition. In this study, we try to use such a carbon-coated anodic aluminum oxide (CAAO) film as an enzymatic electrode and examine how its straight nanochannels are beneficial for the ease of the mass transfer. At first, AAO films (pore size: 50 nm, thickness: 70 µm, a size of 1×1 cm2) were prepared and they were carbon-coated by acetonitrile CVD at 800ºC, where the whole surface of AAO films including the inner walls of the nanochannels was entirely covered with a nitrogen-doped carbon layer with a thickness of 5 nm. Enzyme molecules (fructose dehydrogenase (FDH) or bilirubin oxidase (BOD)) were introduced into the nanochannels of the resulting CAAO films and then they were used as a porous electrode for anode and cathode in a biofuel cell. The biofuel cell fabricated from the anode (FDH-immobilized CAAO) and cathode (BOD-immobilized CAAO) output a maximum current of 60 μW/cm2 at 0.3 V in a D-fructose solution of 200 mM, indicating that the mass transfer of both the reactants and products proceeds inside the nanochannels in CAAO and electron transfer between enzyme molecules and the carbon layer is achieved at each anode and cathode. In conclusion, CAAO can indeed be used as anode and cathode electrodes for a biofuel cell. Moreover, as the size, length and density of the nanochannels and the nature of the carbon layer are controllable, they can be easily optimized to furthe increase both the amount of immobilized enzyme, its stability and the diffision of reactants and products into the nanochannels.



212
Electrochemical performance of microporous activated carbon prepared by chemical activation as supercapacitor
Alireza Mirhabibia,*, Ahad Saeidib, Farhad Golestani Farda
a Center of Excellence for Ceramics in Energy and Environment, Iran University of Science and Technology, Tehran, Iran
b School of Materials, Iran University of Science and Technology, Tehran, Iran

Properties of activated carbon depended on pore size and its distribution. In this research microporous activated carbon with high surface area produced by chemical activation. We tried to study the effect of parameters on pore size distribution and surface area of the chemically activated samples. For agricultural waste, such as nut shells, as raw material for carbon source is used. After preparation of the samples, the effect of impregnating ratio, time and temperature of activation is studied. Activated microporous carbon prepared with more than 1800 m2/g surface area and 1-1.2 cm3/g pore volume. For experimental design and optimization of the experiments from Taguchi method was used. Then use microporous activated carbon with high surface area used as supercapacitor electrode. Some electrochemical analysis such as CV and EIS are used. Capacitive of microporous carbon is more than 90 F/g.



214
Graphene-like nanosheets synthesized by natural flaky graphite
Chuan Xiu Yun
School of Earth and Space Sciences, Peking University, Beijing100871, China

Natural flaky graphite was purified by H2O2, a new patent method to produce graphite without sulfur, and used as precursor to prepare exfoliated graphite through microwave irradiated expansion with some chemicals (such as, hydrogen peroxide, nitric acid and acetic acid). With the centrifugation process, graphene was synthesized by using an efficient and simple method under ultrasonic and microwave irradiation at the room temperature. Natural graphite, exfoliated graphite were characterized by XRD (X-ray diffractionmetor) and Scanning Electronic Microscopy (SEM), and resultant graphene was investigated and confirmed by Atomic Force Microscopy (AFM), and Raman micro-spectrometer, and etc. Natural graphite consisted of mainly hexagonal (2H), and a little rhombohedral structure (3R), was beneficial for synthesis of graphene. Graphene-like nanosheets about 1-3 nm, around 3, 5 carbon layers can be synthesized efficiently by microwave and ultrasonic irradiation with natural graphite.



215
Mechanical hydrothermal reduction for nano-graphene synthesis
Le-Qing Fana,*, Jian-Xiao Yanga, Jin Miyawakib, Isao Mochidab, Seong-Ho Yoona
a Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga, Fukuoka 816-8580, Japan
b nstitute for Materials Chemistry and Engineering, Kyushu University, Kasuga, Fukuoka 816-8580, Japan

Graphene has been received great attentions due to its high thermal, electrical, mechanical and optical properties, and also extensive potential applications for electronics, sensor, catalysis, and energy conversion and storage devices. Inevitable chemical reduction in the preparation process of graphene has been considered to be main reasons for birthing defects and ascending production cost. In this study, we successfully prepared very uniform shaped nano-graphene through the novel mechanical hydrothermal reduction method. Graphitized platelet carbon nanofiber (GPCNF) oxide was exfoliated in mixed solvent of ethylene glycol (EG) and deionized water to form nano-graphene oxide solution by ultrasonication and then reduced by pollution-free mechanical hydrothermal method. The reduction conditions were systematically investigated by taking account of the influences of maximum reaction temperature, rotation speed, EG/deionized water ratio and size of graphite oxide. The reduced nano-graphene oxides materials were characterized by UV-vis spectroscopy, transmission electron microscopy, X-ray diffraction, solid-state 13C NMR spectroscopy, X-ray photoelectron spectroscopy and Raman spectroscopy. The results indicated that after mechanical hydrothermal reduction at 110°C for 3 h, the uniform shaped nano-graphene could be obtained.



216
Enhancing the rate performance of graphite anode in Li-ion battery by coal tar derived pitch coatings
Yu-Jin Hana,*, Jae-Seong Yeoa, Jin Miyawakib, Seong-Ho Yoonb
a Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Japan
b Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga,Fukuoka 816-8580, Japan

The various types of anode materials forLi-ion batteries such as graphite, lithium-alloying materials, intermetallic, and silicon have been commercialized and investigated.Among them,graphite materials still keep their importance as anodic materials in Li-ion batteries in terms of cost, availability and electrochemical properties. However, the rate performance of graphite materials is not sufficient for applications in high-power density batteries such as electric vehicles and large-scale backup power supplies. Previous studieshave reported that higher initial Coulombic efficiency and better cyclability could be obtained by coating a thick carbonaceous mesophase layer (ca. 2.5 μm in a thickness) on the surface of spherical natural graphite using coal tar pitch. However, the carbon coating-related research using coal tar pitch has only focused on decreasing the surface area in graphite anode materials and increasing their initial Coulombic efficiency without any consideration of properties of coal tar pitch. This study investigated the effect of pitch coating on the rate performance of graphite materials. For the selection of best pitch, various coal tar based pitches with different softening points and components were prepared and adopted to carbon coating on the graphite materials. Natural and synthetic graphite that werecoated with coal tar pitch with a different softening points of 25°Cto 195°Cand successively heat treated at 800oC and 1000oC under Ar and vacuum atmospheres, respectively. Carbon coated graphites exhibited two times larger capacity even at 5C discharge rate than those of without the pitch coating. In detail, graphite coated with coal tar pitch of high softening point exhibited higher rate performance than that of low softening point. Also, graphite that had been coated with hexane soluble components of pitch exhibited a half lower capacity at 5C discharge rate than the other soluble components. From these results, the enhancement of rate performance may be resulted from a reduction of surface resistance facilitated by thecoatingand heat treatment of coal tar pitch with a high softening point onto the surface of graphite.



217
Improving anodic performances of biomass derived hard carbon
Han Yu-Jina,*, Jae-Seong Yeoa, Min-Hyun Seob, Jin Miyawakib, Yoon Seong-Hob, et al.
a Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Japan
b Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga, Fukuoka 816-8580, Japan
Hard carbon is considered a promising anodic material in Li-ion batteries for applications to electric vehicles and large-scale backup power supplies due to its high reversible capacity, good rate capabilities and low cost of production. However, the first-cycle Coulombic efficiency and cyclability of hard carbon are still not sufficient for its commercialization for Li-ion batteries. In our previous work, we showed that mangrove-charcoal-derived char heat treated at 1000°C possessed the highest available discharge capacity of 463 mAhg-1, the first-cycle Coulombic efficiency of 73.7%, good rate and cyclability. It was also found that the mangrove-char-derived carbon carbonized in vacuum showed a lower irreversible capacity of 58 mAhg-1 than that in Ar atmosphere due to the formation of pyrolytic carbon film on the surface, and the reduction of the BET surface area, amount of heteroatoms and hydroxyl groups. These results suggest that mangrove-charcoal-derived carbon could be used as an effective anode material for Li-ion batteries. However, the previous studies have only focused on anodic performances of mangrove-char-derived carbon. Because the distillation in the ground is not a suitable for steady supply of mangrove char with a stable quality, it is indispensable to develop a mass production method of mangrove char from raw mangrove wood. The present study is aiming at improving the first-cycle Coulombic efficiency of mangrove-derived hard carbon by changing the preparation conditions of char from a raw mangrove wood and to find out the optimum preparation conditions of mangrove charcoal to give the highest first-cycle Coulombic efficiency. The optimum fabrication condition of mangrove charcoal from raw mangrove wood was found to be at 500°C in inner gas at 0.7MPa for 28 days. Hard carbon prepared under the optimum fabrication condition exhibited the first-cycle Coulombic efficiency of 78.2% and discharge capacity of 441 mAh g-1. The high first-cycle Coulombic efficiency was considered to be obtained due to the low H/C and Odiff/C ratios, and pore structure suitable for Li-ion intercalation/de-intercalation.


219
Characterization of naphtha cracked oil derived spinnable isotropic pitches prepared by different synthetic routes
Byung-Jun Kima,*, Jianxiao Yangb, Osamu Katob, Jin Miyawakib, Seong-Ho Yoonb, et al.
a Interdisciplinary Graduate school of Engineering Sciences, Kyushu University, Japan
b Institute for Materials Chemistry and Engineering, Kyushu University, Japan

Spinnable isotropic pitches for applying to pitch based long carbon fiber were prepared through different two methods of bromination-dehydrobromination and simple distillation methods using naphtha cracked oil (NCO). NCO was used as a raw material for the spinnable isotropic pitch for this study. Bromine was employed to carry the bromination-dehydrobromination reaction at 120oC. Bromine content was controlled to 20% against NCO amount. After the reaction, the obtained pitch was continuously heat treated at 320oC for obtaining basic pitch. The distillation reaction was carried out by simple heat treatment at various temperatures for obtaining basic pitches. The obtained basic pitches from the two methods were finally vacuum-distillated for obtaining spinnable isotropic pitches. All obtained spinnable pitches showed excellent spinnability on the mono-filament base spinning tests. The yields and softening points of spinnable pitches through the reactions of bromination-dehydrobromination and simple distillation were 40% and 20%, and 250°C and 242°C, respectively. The aromatic molecular compositions of NCO and prepared spinnable pitches were analyzed by gas chromatography-atomic emission detector (GC-AED), which could carry the quantitative aromatic compositions of total molecules. GC-AED results revealed that NCO was principally composed of 2-aromatic ring compounds by around 85%. The spinnable pitch prepared by bromination-dehydrobromination was mainly composed of 3, 4-ring compounds, whereas the pitch by simple distillation showed 2 ~ 6 ring compounds as main aromatic composition. Nevertheless the composition of lower condensed ring compounds, the pitch prepared by bromination-dehydrobromination showed higher average molecular weight than that of the pitch by simple distillation, which meant the reaction of bromination-dehydrobromination could afford more linearity and flexibility through the formation of methylene bridges between the aromatic molecules.



220
Preparation of carbon nanofiber using various hydrocarbons under the coexistence of CO2
Kazuya Isomotoa,*, Akinobu Imamuraa, Jin Miyawakib, Isao Mochidac, Seong-Ho Yoonb
a Interdiscliplinary Graduate School of Engineering Science Kyushu University, Japan
b Institute of Materials Chemistry and Engineering Kyushu University, Japan
c Research and Education Center of Carbon Resources Kyushu University, Japan
Carbon nanofiber (CNF) is very expected to apply to wide range of energy saving and environmental protection fields because of its variety in morphologies and surface properties. In previous study, we found out that iron-based catalysts can produce CNF in high yield using carbon dioxide mixed ethylene gases. Interestingly, in such preparation system, some of CO2 were converted into CO and continuously changed into CNF. From these result, we can produce CNF using wasted exhausted gases from chemical plants even if there contains some amounts of CO2. Wasted exhausted gases from chemical plants have usually various kinds of hydrocarbon gases to clarify what kind of hydrocarbon can be converted into CNF even the coexistence of carbon dioxide. In this study, we tried to prepare CNF using methane, ethane and acetylene under the coexistence of CO2. Acetylene produced CNF in higher yield than ethylene. In addition, Acetylene produced CNF higher CO2 concentration and reaction temperature than ethylene. However, Methane and Ethane failed to produce CNF under the coexistence of CO2. From these results, we conjectured that hydrocarbon gases having a multiple bond in the molecular structure tended to produce CNF in high yield under the coexistence of CO2.


221
Enhancing the electrochemical performance of graphite anodes through addition of natural graphite/carbon nanofibers in lithium-ion batteries
Tae-Hwan Parka,*, Yu-Jin Hana, Jin Miyawakib, Isao Mochidac, Seong-Ho Yoonb
a Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Japan
b Institute for Materials Chemistry and Engineering, Kyushu University, Japan
c Research and Education Center of Carbon Resources, Kyushu University, Japan
High capacity, long life, high rate performances and safety are essential for the practical use of Li-ion batteries. These properties are principally related to the characteristics of the carbon material used as an anode in the Li-ion batteries. Graphitic materials are commonly used as anodic materials in commercial Li-ion batteries due to their low, flat potential at discharge, stability, and safety in long-life use. Recently, high rate performances in the Li-ion batteries cause great attentions because of the commercialization of electric vehicles (EV). Graphite can be divided into two categories: (i) natural micro- or macrocrystalline graphite (found as an earth mineral) and (ii) synthetic graphite obtained through high-temperature treatment of graphitic material, usually at around 3,000°C. Natural graphite (NG) is regarded as one of the most attractive anodic materials for Li-ion batteries because of its high discharge capacity, lower discharge potential, and cost competitiveness. However, its limitations, such as low 1st cycle coulombic efficiency, poor cyclability, and poor rate performance, are its main weaknesses for commercialization. Also, synthetic graphite suffers from poor rate performance at high hourly rates (C-rates), which limits its broad application in Li-ion batteries for electric vehicles. In previous reports, cyclabilty and rate performance were effectively improved in the natural graphite/carbon nanofiber (NG/CNF) composite. In this study, we attempted to improve the rate performance of synthetic graphite through the suitable introduction of nano-scaled internal pores into the mesophase pitch-derived synthetic graphite matrix. As a result, hybridized graphite with 10 wt% of added NG/CNF composite exhibited the most improved electrochemical performance in terms of cyclability (99.2% retention rate after 30 cycles) and rate performance (90% retention rate after a 5C discharge rate test). The internal pore volume in the hybridized composites was efficiently controlled via variation of the composition of NG/CNF into the synthetic graphite matrix. Addition of NG/CNF to the synthetic graphite matrix also reduced volume expansion of the electrodes after the high rate test. The electrical conductivity of the hybridized composites was significantly increased, from 457 S cm–1 to 1618 S cm–1, by hybridization of mesophase pitch-derived synthetic graphite with NG/CNF. These results show that the better cyclability and rate performance of the hybridized composites could be ascribed to the buffering effect of internal pores, which prvides facile strain relaxation during electrode structure changes by volume expansion of of graphite during cycle processes, and the electronic contact through carbon nanofiber between natural graphite and synthetic graphite matrix. Addition of the NG/CNF composites introduced effective internal pores inside the synthetic graphite matrix, thereby improving the rate performance and cyclability without compromising the 1st cycle coulombic efficiency.


222
H2S removal using activated carbon from waste palm tree trunk
Nor’Azizi Bin Othmana,*, Taegon Kimb, Akinobu Imamuraa, Jin Miyawakib, Seong-Ho Yoonb, et al.
a Interdisciplinary Graduate school of Engineering Sciences, Kyushu University, Japan
b Institute for Materials Chemistry and Engineering, Kyushu University, Japan
H2S removal of activated carbons prepared from a waste palm trunk were investigated. A dried waste palm trunk WPT was first pulverized and sieved to 100–250 μm, and then carbonized and activated by steam or KOH activation method. The obtained steam-activated bio-char was designated as SAC and KOH-activated bio-char was designated to as KAC. H2S removal performance of the WPT-derived activated carbons, SAC and KAC, were carried out by using a home-made fixed-bed reactor. As a reference, a commercially available activated carbon fiber, OG7A, was also tested. The H2S/N2 mixed gas was diluted with pure N2 to be 50 ppmv of the inlet H2S concentration, and introduced through the sample at total flow rate of 50 mL/min. The outlet gases were periodically collected in gasbags, and the H2S concentrations were measured using a gas chromatography. H2S breakthrough curves for SAC and KAC and results of OG7A, a commercial activated carbon fiber, are as a benchmark. Breakthrough times were calculated. Regardless of the much higher specific surface area of KAC, SAC showed the remarkably long breakthrough time of 390 min; as compared with the commercial activated carbon fiber having similar porosity, the breakthrough time of SAC was more than 8 times longer. Although KAC and OG7A showed steep uptakes of the outlet H2S concentration after the breakthrough times passed, the breakthrough curve of SAC relatively gradually increased with time. Therefore, total removed amount of H2S by SAC was much larger than that by KAC or OG7A, more than 11 or 15 times, respectively . The results suggest that porosity is not necessarily the predominant factor for the H2S removal. Also, the large oxygen content of KAC seemed not to contribute to increase the H2S removal capability. It was found that high specific surface area is not necessarily indispensable, but minerals involved in the WPT-derived activated carbon were suggested to be effective for the H2S removal. It was suggested that minerals contained in the steam-activated carbon acted effectively to remove H2S.


223
Preparation of titanium oxide entrained CNTs and its electrochemical properties
Ryohei Miyamaea,*, Min-Hyun Seob, Tae-Gon Kimb, Jin Miyawakib, Seong-Ho Yoonb, et al.
a Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Japan
b Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga, Fukuoka 816-8580, Japan
Metal oxides such as Ni, Mn, Co, Zn, Sn and Ti have been attracting great attentions as anode materials for novel rechargeable batteries such as Na-ion battery due to their high capacity, low cost, low toxicity and high abundance. Among them, titanium oxide (TiO2) is a well-known important functional material used for electrochemical electrode applications; TiO2 as anode has the advantage of avoiding solid electrolyte interphase (SEI) formation due to its discharge potential range and relatively stable cycle performance. However, the intrinsic low electronic conductivity leads to a relatively poor rate capability, which limits its practical industrial application. Therefore, recently many efforts have been made to improve the poor rate capability of Ti-based electrodes. Carbon nanotube (CNT) has a notably high electric conductivity, especially in an axial direction. Moreover, intrinsic internal spaces of CNT allow materials to be stored inside. These characteristic features of CNT suggest that an encapsulation of TiO2 in the inside of CNT could not only increase the electric conductivity but also avoid formation of dendrite at outside of CNT, which would improve battery performance together with the safety issue. Here, we designed and prepared novel anode materials of TiO2 entrained CNTs for the useful application to the secondary batteries. Well-entrained TiO2 anatase nanoparticles were successfully filled to the inside of special CNTs. Specially designed CNT with nanogates allowed Li, Na, sulfur-ions to pass through between inside and outside of CNT. The investigation of electrochemical properties is now under progress.


226
Morphology and non-isothermal crystallisation of poly(ethylene terephthalate)(PET)/graphite oxide(GO) nanocomposites
Sandra Paszkiewicza,*, Anna Szymczykb, Zdeno Špitalskýc, Jaroslav Mosnáčekd, Zbigniew Roslanieca
a West Pomeranian University of Technology Insitute of Materials Science and Engineering
b West Pomeranian University of Technology Institute of Physics
c Polymer Institute, Slovak Academy of Sciences
d Polymer Institute, Centre of Excellence FUN-MAT, Slovak Academy of Sciences

Graphene–based fillers have been used in polymer nanocomposites and hold potential for a variety of possible applications. To achieve large property enhancements in their nanocomposites, layered materials such as GO must be exfoliated and well dispersed in the polymer matrix. Among other methods, in situ polymerization might offer superior dispersion of this filler [1]. Nanocomposites based on poly(ethylene terephthalate) (PET) and graphite oxide (GO, 5μm) were synthesised by melt transesterification and subsequently polycondensation as follows [2]. Covalent functionalization of exfoliated GO has been used in an effort to compatibilize the filler with polymer hosts for improved dispersion. Morphology of the nanocomposites has been examined by electronic microscopy (SEM, TEM). Using of SAXS and DSC methods, the nanostructure of PET/GO nanocomposites and neat PET was investigated in real time in the process of crystallization from the melt. The correlation function approach was used to analyze SAXS data. Changes in long period values, thickness of crystalline lamellae, thickness of amorphous layers, degree of crystallinity during cooling from the melt were discussed.

This work is sponsored by European Project MNT ERA NET 2012 (project APGRAPHEL). The experiments performed at A2 in HASYLAB (DESY, Hamburg) were done using the beamtime of the proposal II-20110255EC.

References :

  1. Steurer P., Wissert R., Thomann R., Mulhaupt R., “Functionalized graphenes and thermoplastic nanocomposites based upon expanded graphite oxide”, Macrom. Rapid Comm. 2009, 30, 316-27
  2. Paszkiewicz S., Szymczyk A., Špitalský Z., Soccio M., Mosnáček J., Ezquerra T.A., Z. Rosłaniec, “Influence of EG on electrical conductivity of PET/EG nanocomposites prepared by in situ polymerization”, J Polym Sci: Part B: Polym Phys 2012, 50, 1645-52


227
LIQUID PHASE OXIDATION FOR THE PREPARATION OF GRANULAR ACTIVATED CARBONS FROM GRAPE SEEDS BY CYCLIC OXIDATION-DESORPTION
M.A. Gilarranz, Diana Jimenez-Cordero, Francisco Heras, Noelia Alonso-Morales, Juan J. Rodriguez
Universidad Autónoma de Madrid

Activation of grape seeds char upon cyclic activation by liquid phase oxidation/desorption permits a controlled development of porosity versus burn-off using nitric acid, hydrogen peroxide and ammonium persulphate. In this work the influence of activating agent (HNO3, H2O2, (NH4)2S2O8), the desorption temperature (850-950ºC) and the number of cycles (1-10) is studied. A high increase of BET surface area is obtained using HNO3 like activating agent in the first five cycles, reaching BET surface area values higher than 1200m2/g for a burn-off lower than 50%. In the case of the activation with H2O2 and (NH4)2S2O8 significantly lower development of porosity is observed, with respective values of 600 and 800 m2/g for 50% burn-off. The analysis of the pore size distribution showed that porosity generation takes place by the creation of new micropores and by widening of existing micropores in the case of activated carbons prepared with HNO3 and (NH4)2S2O8, whereas the use of H2O2 only led to the widening of the narrow micropores previously existing in the starting char. The activated carbons obtained are essentially microporous, with some significant contribution of mesoporosity in the case of those activated with HNO3 (Vmicro= 0.69cm3/g; Vmeso= 0.07cm3/g) The activation with (NH4)2S2O8 and H2O2 can provide activated carbons with very low mesopore contribution (Vmeso= 0.04 and 0.01cm3/g) and mean micropore size below 1.5nm. SEM characterization showed that the activated carbon maintained the granular morphology of the seeds after 10 cycles also showing an egg shell structure with a wall thickness of about 200mm.



228
DEVELOPMENT OF POROSITY UPON PHYSICAL ACTIVATION OF GRAPE SEEDS BY OZONE OXIDATION-DESORPTION CYCLES
Juan J. Rodriguez, Diana Jimenez-Cordero, Francisco Heras, Noelia Alonso-Morales, Miguel A. Gilarranz
Universidad Autónoma de Madrid

Cyclic oxygen chemisorption-desorption activation consists of a chemisorption step at low temperature followed by desorption in an inert atmosphere at high temperature. The purpose of this work is to study the influence of operating conditions in the development of porosity during the activation of grape seeds char with ozone as activating agent to obtain granular activated carbons. The variables studied were ozone oxidation temperature (250-275ºC), desorption temperature (850- 950ºC) and number of activation cycles (1-10). The starting char was prepared by flash pyrolysis at 800ºC (SBET: 47m2/g, SDA: 505 m2/g).

Under all the combinations of oxidation and desorption temperature studied, the burn-off increased almost linearly with the number of activation cycles. The burn-off was higher for an oxidation temperature of 275ºC. The highest development of surface area also corresponded to this oxidation temperature. After 7-9 activation cycles, activated carbons with SBET higher than 1200 m2/g and SDA higher that 1500m2/g were obtained. Only 5-6 activation were needed to obtain activated carbons with SBET close to 850 m2/g at a burn-off lower than 40%. All the activated carbons prepared were highly microporous, with some macroporositiy and a negligible contribution of mesoporous. The mean micropore size increased with the number of activation cycles due to widening of previously existing pores, while mean mesopore size decreases along the cycles. Some mesoporosity development was observed once the activated carbons achieved a micropore volume of around 0.20 cm3/g. The samples of higher porosity (VMICRO: 0.52 cm3/g) showed a mesopore volume lower than 0.05 cm3/g. The morphology of activated carbon was evaluated by SEM, showing that it maintained granular morphology and a hollow core structure even after 10 activation cycles due to low burn-off.



229
Feasibility of elaborating quaternary mixtures of vegetable oils for the biodiesel production
Lecia Freirea, Ieda Santosa, Luiz Soledadeb,*, Angela Cordeiroc, Antonio Souzaa, et al.
a Laboratório de Combustíveis e Materiais, Departamento de Química, CCEN, Universidade Federal da Paraíba, Campus I, CEP 58059-900, João Pessoa, PB, Brazil
b Campus de Pinheiro, Universidade Federal do Maranhão, CEP 65200-000, Pinheiro, MA, Brazil
c Instituto Federal de Educação, Ciência e Tecnologia do Amazonas – IFAM, CEP 69083-000, Manaus, AM, Brazil

The philosophy used for the selection of coal blends has always consisted of placing together coals with different defficiencies, in such a way that the advantages of one coal offset the disadvantages of another. For instance a high ash/ low sulfur coal with a low ash/ high sulfur coal. Therefore, although very few/expensive coals meet the standards for met coke production, the blend does make more sense both technically and costwise.

The extrapolation of this concept to other raw materials for energy generation has not been much common. For example, the biodiesel production, in most of the cases has been supported by one only vegetable oil or animal fat.

The present work describes the extrapolation of the coal blending concept for the raw materials which biodiesel is comprised of. In the specific case studied, four vegetable oils (soybean, cotton, jatropha curcas and babassu) were used.

The vegetable oils based on saturated fatty acids tend to display excellent oxidative stability and bad properties of low temperature flow. Conversely, the ones based on mono and polyunsaturated fatty acids display good low temperature flow and poor oxidative stability.

The extrapolation of the coal blending philosophy allowed that quaternary blends from the fore aforementioned raw materials displayed adequate values for the tests of pour point, cloud point and kinematic viscosity, related to low temperature flow, as well as for the tests of PDSC, Petro-Oxy and Rancimat, which deal with the oxidative stability. These results are discussed throughout the paper.



230
Vitreous carbon obtained from glassy carbon powder: vantages and advantages
Fabio Dondeo, Alvaro Damião
Instituto de Estudos Avançados

Monolithic vitreous carbon — MVC — is a low density carbonaceous material suitable for several industrial applications due to properties such as good electrical conductibility, resistance to high temperatures, biocompatibility, and chemical inertness.

MVC traditionally is produced from the cure of a carbon rich resin followed by a slow carbonization process due to thermal limitations of this material. MVC samples with thicknesses exceeding 7 mm are uncommon to obtain as the loss of volatiles during the carbonization process generates stress, causing cracks. Nearly 20% of the samples break due to the presence of large pores which could not be eliminated during the centrifugation and cure of the resin.

This work presents the characterization of CVM obtained by an alternative route to efficiently prepare thicker MVC pieces. It is based on the use of partially or completely carbonized furfurilic resin micrometric powder. This material is crushed in a ball mill; the resulting powder was sifted and classified according to particle size. Sieves with aperture sizes of 149, 105, 74, 62, 44 and 37 μm were used forming two different groups: one with particles smaller than 37 μm, and another with particles between 37 and 44 μm, and so on. Poly-furfuryl alcohol resin was added to the selected size powder. The mixture was then homogenized and compacted in a mold, using a hydraulic press, with controlled charge. Samples were carbonized to 1100 ºC in a furnace in nitrogen atmosphere. The percentage of broken pieces was strongly reduced to less than 5%. After carbonization, the samples were polished for surface characterization. Linear and 2D roughness were measured. Surface structures were observed by light and confocal laser microscopy. The micrographs were used to calculate surface porosity with the ImageJ software. Apparent density was calculated using a high precision analytical balance. X-ray diffraction was measured to detect phases and amorphicity.

Samples with 15 mm thicknesses were obtained, clearly exceeding the limit of the traditional method. While the density of MVC obtained with the traditional method is close to 1.5 g/cm3, the apparent density of MVC samples obtained from powder phase ranged from 1.2 to 1.4 g/cm3 depending on the pressure applied and on the average size of particles employed. These smaller apparent density values occur due to voids between grains. The application of thinner particles, higher charges or combination of powder with different average size contributes to the increase of density. Arithmetic mean roughness (Ra) values vary from 0.7 to 5.1 μm and tend to increase with grain size. Surface porosity calculated (with 25X magnification) is nearly constant for all samples: 30%, however the average pores size is strongly reduced for samples produced with thinner particles. X ray diffraction of these samples showed that bulk material presents a large broad amorphous like peak due to CVM, an additional small sharp peak corresponding to graphite. The origin of this crystalline phase will be discussed.



232
ALKALI PHENOLATES IN GRAPHENE: ELECTRONIC AND GEOMETRIC EFFECTS IN CATALYTIC GASIFICATION
Ljubisa Radovica, Camila Morab,*, Antonio Buljanb
a University of Concepcion and Penn State University
b University of Concepcion

The effectiveness of metals in both heterogeneous catalysis and electrocatalysis on carbon surfaces is known to be a complex interplay of electronic and geometric factors. In particular, the importance of alkali metal phenolates (C-O-M moieties) in catalytic carbon gasification is well documented. The objective of the present study is to take advantage of the power of computational quantum chemistry to explore fundamental phenomena whose experimental elucidation has been particularly difficult, and at best indirect: (a) how is the electron density at the reactive carbon site affected by the presence of alkali phenolate groups in its vicinity, and (b) how does the orientation of the phenolate group at the graphene edge affect the accessibility of a gas molecule to the reactive site. Initial results in this endeavor will be presented and discussed.



233
Controlled and catalytic fluorination to prepare graphene and fluorinated graphene
Marc Duboisa,*, Monica Craciumb, et al.
a Institut de Chimie de Clermont-Ferrand UMR CNRS 6296 Clermont Université
b Centre for Graphene Science, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Physics building, Exeter EX4 4QF, UK

Graphene, an infinite two-dimensional layer consisting of sp2 hybridized carbon atoms, has been attracting considerable interest in recent years because of its unique band structure and physical properties. The preparation of fluorinated graphene is still a real challenge because of its reactivity with fluorine gas, even diluted with an inert gas (N2 or Ar). Graphene strongly reacts with molecular fluorine F2 to form volatile CF4 and C2F6 species. In other terms, graphene burns in fluorine atmosphere. Our strategy consists then to fluorinate graphite flakes and to perform a mechanical exfoliation. Xenon difluoride has been chosen as fluorinating agent (FA). This method results in a homogenous dispersion of fluorine atoms into the whole volume of graphite, contrary to F2 gas, and favours the mechanical exfoliation by cleavage of the fluorocarbon sheets [1,2].

Fluorination allows also non-fluorinated graphene materials to be synthesized using two strategies:

i) Using a two-step strategy with controlled fluorination (with solid FA) followed by a thermal defluorination [3]; the synthesis of sub-fluorinated graphitized nanodiscs was first performed. The fluorinated parts must be homogenously dispersed in the carbon lattice with a non-fluorinated core (the process is called sub-fluorination). A controlled fluorination using solid FA (TbF4) was then preferred rather than the direct process using F2. Whatever the fluorination method, the removal of the fluorinated parts during a process similar to a peeling with CF4 and C2F6 gas evolution does not result in damages of the non-fluorinated region. Multilayer carbonaceous nanomaterials were synthesized in a form of ruffled paper [4]. The discs fold up on themselves during thinning.

ii) A chemical exfoliation of graphite fluorides (GFs) prepared at room temperature. Contrary to the conventional method using F2 at high temperature in the 300-600°C range, the fluorination of graphite can be performed at room temperature thanks to a catalytic gaseous mixture of F2, HF and iodine pentafluoride IF5. The resulting room temperature GFs contain intercalated residual catalysts, such as IF5, IF6- and IF7 and the covalence of the C-F is weakened in comparison with high temperature GFs. In order both to strengthen the C-F bond and to remove the residual catalysts, a post-treatment was carried out. The resulting samples were then exfoliated using a thermal shock. Fast evolution of gaseous iodine species resulted in the exfoliation/defluorination of graphite. The thermal defluorination and the nature of the sheets were investigated by thermogravimetry and electronic microscopies, respectively. Electrochemical discharge in primary lithium battery was also used to check the presence of residual C-F bonds and their covalence. This underlines that non-fluorinated graphene can be obtained by this original way. Finally, the dispersion of those samples was studied in different polar and non-polar solvents; In order to enhance the dispersion, the graphene materials were post-fluorinated.

[1] Withers et al, Phys. Rev. B 2011;82:073403.

[2] Withers et al, Nano Lett., 2011;11:3912.

[3] Ahmad et al, Carbon, 2012;50:3897.



234
Extra-capacity in primary lithium battery using new fluorinated nanocarbons
André Hamwia,*, Yasser Ahmada, Marc Duboisa, Katia Guérinb
a Institut de Chimie de Clermont-Ferrand UMR CNRS 6296 Clermont Université UBP
b Institut de Chimie de Clermont-Ferrand UMR CNRS 6296 Clermont Université UBP

When fluorinated carbons (denoted CFx) are used as electrode material in primary lithium battery, the C-F bonds are broken during the electrochemical discharge and carbon and LiF particles are formed. Then, the higher the fluorine content, the higher the theoretical capacity, the maximal value being 865 mAh/g for a CF1 composition. Although this limitation, we found higher capacities (Cexp) than the theoretical ones (Ctheo) for several optimized fluorinated nanocarbons. The faradic yield, defined as 100xCexp/Ctheo, was then higher than 100% and reached even 170 %. This means that a second electrochemical process takes place after the defluorination. In order to understand such additional mechanism, a set of carbonaceous nanomaterials, namely carbon nanodiscs, graphitized carbon blacks, double- and multi-walled were fluorinated using either pure F2 gas or a solid fluorinating agent (TbF4) [1] and their electrochemical performances were investigated. After a deep characterization of the material (SEM, TEM, XRD, 19F solid state NMR, EPR), the discharge mechanisms were investigated using the same complementary techniques and compared to conventional graphite fluorides. This systematic study of about ten different CFx underlined that the key point for the extra-capacities lies in both the maintaining of some unfluorinated parts and the ability of the fluorinated carbon to reform its raw structure after electrochemical defluorination are necessary for extra-capacity. LiF particles, which are formed during this process, are then located outside the new carbonaceous matrix and may participate to the second mechanism, similar to the intercalation into the freshly formed carbon matrix. These two processes, electrochemical defluorination and intercalation into the defluorinated carbon are well exemplified by the case of carbon nanodiscs. This sample was fluorinated with TbF4 in order to homogenously locate the fluorine atoms in the whole volume of the discs, except in the central discs, less or not fluorinated. The deep characterization of the fluorinated discs allows this conclusion to be proposed in accordance with the properties of the starting materials [2]. After the defluorination, a shell of agglomerated LiF particles covered the discs. Any exfoliation of the discs has been observed after the defluoration contrary to the studied conventional graphite fluoride. The process similar to an intercalation into the reformed discs may take place thanks to the maintaining of the discotic geometry. The extra-capacity comes from this additional process, which occurs through the LiF shell. In other words, the less or not fluorinated central discs act as a reinforcement that allows the rebuilding of the carbon matrix. The necessity of a reinforcement was then confirmed for the cases of fluorinated double and low diameter multi-walled carbon nanotubes, for which the fluorination with F2 gas has been conducted in order to avoid the fluorination of the inner tube [3], which allows the reinforcement and the carbon rebuilding. The higher faradic yield (170%) was obtained for those samples [4].

[1] Zhang et al, Carbon, 2008;46(7):1017-1024 and 1010-1016.

[2] Ahmad et al, Carbon, 2012 ;50:3897.

[3] Zhang et al, Phys. Chem. Chem. Phys., 2010;12 :1388-1398.

[4] Dubois M, Guérin K, Hamwi A, French patent, FR 1261927.



235
THE GRAPHENE-NO REACTION: INITIAL INSIGHTS FROM COMPUTATIONAL QUANTUM CHEMISTRY
Ljubisa R Radovica, Andrea Oyarzunb,*, Ximena Garciab
a University of Concepcion and Penn State University
b University of Concepcion

The reaction between carbon and nitric oxide is as complex as that of carbon with O2. Its importance has grown tremendously over the past several decades, as society struggles to prevent acid rain and smog formation through NOx reduction. Use of carbon as a convenient reducing agent (e.g., 2C+2NO = C + CO2 + N2), or even better as a catalyst (2C + 2NO = O2 + N2), has been hampered by a lack of understanding of key details of the reaction mecanism. Here we use computational quantum chemistry to explore similarities and differences with respect to the much better understood, both experimentally and theoretically, carbon combustion reaction. We emphasize the adsorption process on zigzag and armchair sites of graphene, keeping in mind that, once the carbon-oxygen surface complexes are formed, the similarities between the two reactions are likely to increase (e.g., 2C(O) = C + CO2).



238
Energetic Parameters Determination in Adsorption and Immersion of different adsorbates on activated carbon
Rodriguez Paolaa,*, Giraldo Lilianaa, Moreno Juanb
a Universidad Nacional de Colombia
b Universidad de los Andes

The porous structure on adsorbent determines the adsorption capacity of the same on various applications, several adsorbates that are commonly used to determine solid surface characteristics, nitrogen at 77 K and carbon dioxide at 273 K, are the most frequently, another adsorbate employed is benzene at 293 K. This investigation presents the design and construction of a vapor adsorption device on porous solids, in determining adsorption isotherms of benzene over a granular activated carbon that was produced ​​from coconut shell (GAC).

The solid was characterized by N2 and CO2 adsorption on a common device and gave following textural parameters: the surface area value, SBET, is 842 m2g-1, the total micropore volume value, Vo, is 0.34 cm3g-1 and narrow micropore volume, Vn, is 0.35 cm3g-1. The surface chemistry of the solid was checked by determining the pH in the point of zero charge, pHPZC, acidity and basicity total, the obtained results are: 5.4, 0.141 and 0.065 molecules nm-2 respectively.

There were determined adsorption capacity and the immersion enthalpy of benzene on GAC in devices of local construction; the results were correlated to evaluate energetic and textural parameters using both techniques. The benzene adsorption capacity determinate was 7.17.mol C6H6 and immersion enthalpy was -106.4 ± 0.5 Jg-1.

Key words: benzene adsorption, activated carbon, immersion calorimetry



239
CO2 adsorption on activated carbon monoliths with nitrogen chemical groups
Vargas Dianaa,*, Giraldo Lilianaa, Moreno Juanb
a Universidad Nacional de Colombia
b Universidad de los Andes

The development of materials with potential application for CO2 capture is a topic of great scientific interest. Activated carbons (AC) can be conveniently used as CO2 adsorbents thanks to their microporous structure and tunable chemical properties. In this work, two AC honeycomb monoliths were synthesized starting from African palm stones, through activation either with H3PO4 or ZnCl2 solutions. A surface functionalization was performed in order to add nitrogen groups, aiming at an enhancement of CO2 adsorption capacity. This chemical modification was performed either with ammonia in gas phase or a 30% ammonium hydroxide aqueous solution, on both AC monolith samples. The original and modified monoliths were characterized by N2 adsorption at 77 K, infrared spectroscopy, Boehm titration and immersion calorimetry in benzene and water. CO2 adsorption on both raw and functionalized AC monoliths was evaluated in a volumetric equipment at a temperature of 273 K and until 1 bar, and values ​​ranging between 120-220 mg CO2 gAC-1 were obtained. The experimental results indicated that both methods of chemical modification determined an increase in the content of superficial nitrogen groups and thus an increase in CO2 adsorption capacity, being the treatment with ammonium hydroxide slightly preferable.

Key words: CO2 adsorption, activated carbon monoliths, nitrogen chemical groups, immersion calorimetry, hydrophobic factor



241
Highly oriented C/C composites with high thermal conductivity
Guanming Yuan, Xuanke Li, Zhijun Dong, Zhengwei Cui, Ye Cong
Wuhan University of Science and Technology

Using mesophase pitch as a starting material, smooth ribbon-shaped carbon fibers were prepared by melt-spinning, oxidation stabilization and further heat treatment at a low temperature. Utilizing such pretreated fibers as matrix material, followed by coating some mesophase pitch binder on them, one-dimensional carbon/carbon (C/C) composites were fabricated by a hot-pressing method at a relatively low temperature (~500oC). The C/C composites with low electrical resistivity and high thermal conductivity along the longitudinal direction of the ribbon fibers could be obtained through subsequent carbonization and graphitization. The results show that the shape and structure of ribbon fibers can be nearly maintained integrity without any damage in the process of hot-pressing and subsequent heat treatment. XRD, PLM and SEM analyses indicate that the ribbon-shaped fibers have been unidirectionally distributed in the composite block and the main planes of the wide ribbon fibers are orderly accumulated along the hot-pressing direction. The internal graphitic layers possess a higher degree of preferred orientation parallel to the longitudinal direction of the ribbon fibers. The electrical resistivities and thermal conductivities of the C/C composites are respective decreasing and increasing with the rising of heat-treatment temperatures. For the samples made with 1.5 mm wide ribbon fibers after graphitization at 3100oC, the bulk density and electrical resistivity approach 1.86 g/cm3 and 1.5 μO.m, respectively. Their thermal conductivity and thermal diffusivity along the longitudinal direction of the ribbon fibers at room temperature are measured to be as high as 896 W/m.K and 642 mm2/s, respectively.



244
Adsorption mechanism of fluoride in zirconium-impregnated activated carbon
Litza H. Velazquez-Jimeneza,*, Robert H. Hurtb, Juan Matosc, J. Rene Rangel-Mendeza
a Instituto Potosino de Investigación Científica y Tecnológica, A.C.
b School of Engineering/Institute for Molecular and Nanoscale Innovation (IMNI), Brown University
c cDepartment of Catalysis and Alternative Energies, Venezuelan Institute for Scientific Research (IVIC)

When activated carbon is modified with zirconium(IV) by impregnation or precipitation the adsorption capacity improves 3-5 times [1,2]. The relatively easy experimental methodology contrasts with the complexity of the conditions of pH, ionic strength, presence of complexing ions, among others, that could affect the aggregation and reorganization of Zr(IV) particles on the surface of carbon materials. These facts are usually ignored or very little explored in research regarding the use of modified carbon materials as adsorbents, but these are a key factor to understand the adsorption mechanism of fluoride. In this study, a commercial activated carbon was modified with Zr(IV) which also involved the use of oxalic acids as a capping agent (OA) to control the particle size of Zr(IV) to maximize the adsorption capacity for F-.

Adsorption experiments were carried out at pH 7 and 25 °C with a fluoride concentration of 40 mg L-1. The ratio organic capping agent to zirconium (OA/Zr) was varied to determine the best conditions to produce an adsorbent with high fluoride adsorption capacity. The data were analyzed by the Langmuir and Freundlich isotherm models. FTIR, XPS and the determination of the surface charge distribution were performed in order to elucidate the fluoride adsorption mechanism. Potentiometric titrations showed that ZrOx-AC posses positive charge at pH lower than 7, and FTIR analyses demonstrated that zirconium ions interact mainly with carboxylic groups contained on the surface of activated carbon. Moreover, Zr(IV) interacts with oxalate ions from the organic capping agent, which suggests that the fluoride adsorption mechanism could be attributed to a –OH exchange from the zirconyl oxalate complex. XPS analysis showed that oxalic acid changes the oxygenated functional groups in carbon surface. The influence of these groups is expected to induce an enhancement in the Zr (IV) dispersion in agreement with an increase in the fluoride adsorption capability of modified carbon material.

The developed material in this study has up to 3 times higher fluoride adsorption capacity than activated alumina or iron-impregnated ceramics, which can help to comply with the fluoride limit in drinking water established by the World Health Organization.

Keywords: activated carbon, impregnation, zirconium, fluoride, adsorption, mechanism

References

1. Janardhana C., Nageswara Rao G., Sathish R.S., Lakshman V.S.; Study on the defluoridation of drinking water by impregnation of metal ions in activated charcoal, Indian J. Chem. Technol. 13 (2006) 414-416.

2. Sandoval R., Cooper A.M., Aymar K., Jain A., Hristovsi; Removal of arsenic and methylene blue from water by granular activated carbon media impregnated with zirconium dioxide nanoparticles, J. Haz. Mat. 193 (2011) 296-303.



245
SELF-PROPAGATING HIGH TEMPERATURE SYNTHESIS OF COMPOSITION MATERIALS ON THE BASIS OF SiC AND TiC
Roza Abdulkarimovaa,*, Zulkhair Mansurova, Bagdatkul Mylyhatb
a Institute of Combustion Problems
b Al-Farabi Kazakh National University

Development of rational technologies with the aim to create construction materials with the designed properties and functions is a very important problem at present. The possibility to synthesize in one stage multicomponent ceramic materials consisting of both one-phase compounds and heterogeneous system, for example, on the basis of carbides, nitrides, oxides is interesting from a scientific point of view and important for practical application. To intensify the processes of self-propagating high temperature synthesis (SHS), the method of mechanical activation is used which is very promising as it not only changes dispersity but also results in power activation of the particles both on the surface and in the volume, as well as in the formation of point and extended defects which finally influence the composition and properties of the material being synthesized.

In the present work refractory SHS-carbon containing multicomponent composition materials in the system SiO2 – Al – C, TiO2-B2O3-Al-C, TiO2-B2O3-Mg - C were created. The possibility of using available carbon containing additives: carbonized rice husk, shungit and wastes of electrode graphite as a source of carbon in this system was shown.

The use of carbon-donating agents was found to increase the amount of silicon carbide SHS products, which improves the refractory properties and strength of synthesized materials.

It was found for the first time that in the course of thermal carbonization of preliminary mechanoactivated quartz there formed a new structural type of nanotubes – nanosize loops which strengthen the obtained material in the subsequent SH-synthesis. It is stated that iron containing inclusions from the walls and balls of the steel vessel of a planetary centrifugal mill contribute to formation of nanosize particles in the course of carbonization.

Also, the possibility to produce composition materials on the basis of boron containing ore of Inder deposit of the Republic of Kazakhstan by SHS method was investigated. Boron containing ore, titanium dioxide (rutile), aluminium, magnesium, graphite and soot were used as initial components. The regularities of the SHS process, composition and structure of SH- synthesis process products were studied. The presence of high temperature phases of titanium boride, titanium carbide, oxides of aluminium, magnesium and their spinels in SHS products was determined by the X- ray phase analysis.

Thus, the possibility of synthesis under the condition of combustion of refractory materials using available mineral raw materials was shown.



246
Characterization of chemical properties of solvent-extracts from metallurgical coal by instrumental analysis
Jung-Chul Ana,*, Seong-Young Leea, Ik-Pyo Honga, Jae-Hoon Choib, In-Kuk Suhb
a Research Institute of Industrial Science & Technology
b Raw Material Research Group of POSCO

Nine metallurgical bituminous coals were heat-treated in the atmosphere-controlled box furnace at different temperatures and the effects of temperature on the amount of solvent-extracts and the aromaticity of coal were investigated in this study. Toluene and Quinoline were used as the extracting solvents. In general, the beta-resin content (i.e., Toluene Insolubles-Quinoline Solubles) of heat-treated coal was increased as temperature increased. Measured maximum fluidity of coal was closely relevant to its beta-resin content as well as its volatile matter content. 1H nuclear magnetic resonance (NMR) study revealed the temperature effect on the variation of aromaticity of heat-treated coal. The aromaticity was measured relatively low for the heat-treated coals at the temperature of 663 and 683K. For coals heat-treated at higher temperature (e.g., 703 and 723K), the measured aromaticity was relatively high. The heat-triggered molecular chain scission & cross linking, radical formation & recombination in coal molecular structure are expected to contribute the aromaticity variation of coal.



247
DEFORMATION OF 1D NANOCRYSTALS AS A FUNCTION OF UNIT CELL SIZE AND SWCNTs DIAMETER.
Andrey Kumskova,*, Nikolay Verbitskiyb, Victoria Zhigalinaa, Lada Yashinac, Andrey Eliseevd, et al.
a Institute of Crystallography RAS
b Department of Materials Science, Moscow State University; Faculty of Physics, University of Vienna
c Department of Chemistry Moscow State University
d Department of Materials Science, Moscow State University

Here we show that after filling of single-walled carbon nanotubes (SWCNTs) with SnTe, AgBr,CuI and CuBr, 1D and 3D crystals are formed in the inner channels depending on SWCNTs diameter. CuI@SWCNT and CuBr@SWCNT nanostructures were formed by capillary filling of preopened nanotubes with various diameters (1.3-2.0 nm) [1]. Using HRTEM as well as image simulation [2] it was shown that 1D crystal of CuI in the SWCNTs with the diameter of 1.3-1.5 nm in the internal channel is hexagonal close-packed or distorted cubic iodine anion sublattice. Also phase transition 1DCuI (hexagonal) ®1DCuI (cubic) sublattice type is observed under a beam irradiation [3]. As the SWCNT diameter is increasing to 1.8 nm only cubic modification is formed with unit cells connected by [001] edges. Such 1D crystal orientation relative to the nanotube provides maximum bonding between anions (cations) of 1D crystal with nanotube walls. When diameter is larger than 2.0 nm the necessity and possibility of 1D crystal formation disappears. The crystal is keeping the specific <110> orientation along the nanotube axis but has a possibility to grow in radial direction and is formed by more than one full cubic unit cell chains.

As supported by the Raman spectroscopy the crystals of copper halides exhibit acceptor behavior as well as chemical bonding between crystal and nanotube wall due to partial hybridization of Cu3d and C2pz orbitals [1]. It is shown that charge transfer is increasing with nanotubes diameter growth as a result of increasing CuI-SWCNT contacts. Chemical bonding is also strongly depends on structure and dimensionality of composites. It can be clearly observed in NEXAFS and XPS spectra in case of 1D CuBr@SWCNT nanostructures and is absent for 2D graphene layer with CuBr deposited on top of it.

1. Eliseev A. A. et al. Interaction between single walled carbon nanotube and 1D crystal in CuX@SWCNT (X = Cl, Br, I) nanostructures. Carbon 50, 4021–4039 (2012).

2. Kumskov A. S. et al. The structure of 1D and 3D CuI nanocrystals grown within 1.5–2.5 nm single wall carbon nanotubes obtained by catalyzed chemical vapor deposition. Carbon 50, 4696–4704 (2012).

3. Kiselev N. A. et al. The structure of nanocomposite 1D cationic conductor crystal@SWNT. Journal of Microscopy 246, 309–321 (2012).



248
Selective removal of benzothiophene and dibenzothiophene from gasoline using double-templates molecularly imprinted polymers on the surface of carbon microspheres
Xuguang Liu, Weifeng Liu, Yongzhen Yang, Bingshe Xu
Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024, China

A novel double-templates molecularly imprinted polymer (D-MIP) on the surface of carbon microspheres (CMSs), using benzothiophene (BT) and dibenzothiophene (DBT) as the template molecules, was prepared for the removal of thiophene sulfides from fuel gasoline. Field emission scanning electron microscopy, Fourier transformation infrared spectrometry and thermogravimetric analysis were used to characterize the structure and morphology of the D-MIP-CMSs. The adsorption behaviors of the D-MIP-CMSs including adsorption kinetics and isotherms were detected in detail by gas chromatography. The D-MIP-CMSs exhibited excellent selectivity affinity toward BT and DBT with higher binding capacity in simulated gasoline compared to non-imprinted polymer (D-NIP-CMSs). The pseudo-second-order model and Langmuir-Freundlich isotherm well described the adsorption of thiophene sulfides on the D-MIP-CMSs. In addition, the dynamic adsorption and regeneration were also investigated. The D-MIP-CMSs provides a new material for using in deep desulfurization of fuel oils.



249
Structure of pyrolytic carbon deposited on carbon matrices
Alexander Tikhomirov, Nataly Sorokina, Kirill Skripnik, Artyom Malakho, Viktor Avdeev
Lomonosov Moscow State University

The number of carbon matrices with different structure and morphology: HOPG, carbon fiber and two types of exfoliated graphite was used to produce carbon-carbon composites by pyrolityc carbon deposition from methane by a Chemical Vapor Infiltration technique. Origin matrices possess graphitic structure varied from turbostratic to highly-ordered one and crystallite size Lc from 2 to 75 nm, specific surface area is from few to 140 m2/g.

Using XRD correlation between perfection of graphitic matrix structure and orderly manner of pyrolytic carbon forming on it was established. The most ordered pyrolytic carbon with Lc = 25 ± 2 nm deposited on HOPG, the least ordered with Lc of about several nm - on original and modified in nitric acid carbon fibers.

The intensity ratio of ID/IG in Raman spectra of pyrolytic carbon which can be used for qualitative estimation of the crystallite size La indicates that PC on HOPG has the largest crystallite size La, pyrolytic carbon deposited on carbon fibers has the smallest La.

Thus, the morphological features of pyrolytic carbon is mostly determined by the nature of the carbon matrix. Pyrolytic carbon formed on hot non-catalytic surfaces of the matrices (carbon fiber - exfoliated graphite - HOPG) is low ordered with Lc from 3 to 25 nm.



250
Reactivity carbon matrices after anodic oxidation in pyrolityc carbon deposition process
Nataly Sorokina, Alexander TIkhomirov, Kirill Skripnik, Artyom Malakho, Viktor Avdeev
Lomonosov Moscow State University

Modification of carbon matrixes (natural graphite and carbonized carbon fiber) was carried out by chemical intercalation (in fuming nitric acid) and by anodic oxidation in a nitric acid solution. The process of pyrolytic carbon deposition by CVI technique from methane at original and modified carbon matrices was studied.

Intercalation of graphite in 98% HNO3 provides formation of graphite nitrate of stage II with identity period Ic = 11.2 Å. As a result of thermal shock of hydrolyzed graphite nitrate at Т=900оС in the air an expansion with formation of nitric exfoliated graphite EG (N) was observed.

Anodic polarization of natural graphite in 58% HNO3 at high potentials (EAg/AgCl>1.5В) provides better oxidation of the carbon matrix and results in a mixture of oxidized graphite and graphite oxide. As a result of thermal shock electrochemical exfoliated graphite EG (E) was obtained.

As a result of intercalation, oxidation and subsequent heat treatment crystalline size decreased from Lc=60 to Lc(EG(N))=36 and Lc(EG(E))=24 nm, the specific surface area increased to SBET(EG(N))=89 and SBET(EG(E))=140 m2/g. Modification results in the surface functionalization with hydroxyl groups and in the case of anodic polarization also with ether, carbonyl and carboxyl groups.

Similar syntheses were conducted with Zoltek carbonized carbon fibers. Intercalation was not observed in any of the cases because of the small size of the crystallites and the highest functionalization was achieved in 58% HNO3 using anodic polarization. After washing that samples contained 15-20 at.% oxygen and shown specific surface area of about 5 m2/g after heat treatment.

Low ordered pyrolytic carbon deposited on the obtained matrix by pulsed pyrolysis of methane.

The rate of pyrolytic carbon deposition was shown to depend on the nature of the matrix. The highest deposition rate, other things being equal, were found for the samples of expanded graphite and carbon fiber, obtained by electrochemical modification in a solution of nitric acid.

The highest deposition rates were fixed at the initial stages of low-density samples saturation CEG (E) with the most advanced surface. The content of pyrolytic carbon in the composite increases linearly with the increase of SBET of original matrix for both types of expanded graphite in the studied range.



251
Effect of Electric potential on Ionic Liquid Structure in Carbon Nanospace
Ryusuke Futamuraa,*, Taku Iiyamab, Toshihiko Fujimoria, Patrice Simonc, Katsumi Kanekoa, et al.
a Research Center for Exotic NanoCarbons, Shinshu University
b Faculty of Science, Shinshu University
c Université Paul Sabatier, CIRIMAT UMR, CNRS 5085

The effect of electric potential on ionic liquid (IL) structure in carbon nanospaces was investigated with wide angle X-ray scattering supported by reverse Monte Carlo (RMC) simulations.

ILs are key materials of the 21 century science because of their unique properties (e.g. negligible vapor pressures and high thermal stabilities). Although the application fields are getting wider varieties, one of the most hopeful areas is electrical device, especially electrical double layer capacitors (EDLCs), which have great potentials as energy storage systems alternating to secondary batteries, due to their wide electrochemical windows and high ionic conductivities.

Since EDLCs store high electrical energy by forming electrical double layer on the interface between the porous carbon electrodes and electrolytes without any chemical reactions, the microscopic understanding of the interaction between carbons and ions and of the ionic behaviors in carbon nanospaces could provide a marked improvement of EDLCs performance. In fact, Chmiola et al. have reported anomalous high capacitances of porous carbon electrodes whose pore widths are less than 1 nm, suggesting that deformation and partial desolvation of solvation structure of ions could directly relate to the high performance. Although the solvated ions and the ion-solvent interaction are essential in conventional EDLCs, the ion and solvent system has some complicate factors to be elucidated. Consequently, solvent free ion systems are promising applicants for this purpose and it should be carried out with ILs to study the role of electric potential on EDL structures of ions in carbon nanospaces.

X-ray scattering measurement is a powerful tool for the investigation of molecular nanoassembly structures confined in pores because of the strong transmissibity of X-ray. So far, we have successfully showed organic solution structures in carbon nanospaces with X-ray scattering methods[1]. In this presentation, we report intermolecular structure of ILs in carbon nanospaces especially under electric potential and the effect of electric potential on the assembly structure with the aid of RMC simulation.

The intermolecular structure of 1-ethyl-3-methylimidasolium bis(trifloromethaneslfonyl)imide (EMI-TFSI) ILs was studied in slit pore of carbide derived carbons and cylindrical pores of single wall carbon nanotubes. We also measured X-ray scattering in positively charged state for SWCNT system.

X-ray scattering curves of EMI-TFSI confined in both carbon nanospaces showed that intrinsic long distance ordering of EMI-TFSI was disturbed in nanospaces. Interestingly, the radial distribution functions of confined ILs derived from Fourier transformation of X-rays scattering curves revealed adlayer formation on carbon surfaces even without any electric potentials. Moreover, the 1st and 2nd neighboring ion numbers became large in positively charged SWCNT pore in which TFSI anions must be selectively adsorbed. To our knowledge, this is a first direct experimental observation for the effect of electric potential on ILs structure in carbon nanospaces and our results would shed light on the unique EDL structure to design optimum EDLCs.

[1]A. Tanaka, T. Iiyama, T. Ohba, S. Ozeki, K. Urita, T. Fujimori, H. Kanoh and K. Kaneko, J. Am. Chem. Soc., 2010, 132, 2112



252
NMR and NEXAFS study of various graphite fluorides
Marc Duboisa,*, Alexander Kharitonovb, Alexander Vinogradovc, et al.
a Institut de Chimie de Clermont-Ferrand UMR CNRS 6296 Clermont Université UBP
b The Branch of the Institute for Energy Problems of Chemical Physics of the Russian Academy of Sciences, Chernogolovka, Moscow Region, 142432, Russia
c V.A. Fock Institute of Physics, St. Petersburg State University, St. Petersburg 198504, Russia

Due to their numerous applications, such as electrode material of primary lithium batteries, solid lubricants, reservoir for storage of strong oxidant and fluorinating agents (BF3, ClF3), graphite fluorides are extensively studied during several decades. For all these uses, the chemical, electrochemical and tribological properties depend strongly of the C-F bonding in the fluorocarbon matrix. The control of the covalence and the fluorine content allows the tuning of the properties e.g. the discharge potential and the capacity in lithium batteries. The higher the covalence, i.e. the higher the strength of the bonding, the lower the discharge potential is. The C-F bonding is highly versatile in fluorinated carbons. The strength of the interaction between the fluorine and carbon atoms can considerably vary from a very weak (van der Waals) one for the case of fluorine adsorption on the surface of carbonaceous material to a strong covalent one in graphite fluorides with (C2F)n and (CF)n structural types, prepared by treatment with molecular fluorine at 350°C and 600°C. Intermediate state, i.e. weakened covalence, can be also obtained according to the fluorination conditions.

Graphite fluorides with different structural types (CyF)n (y = 2.5, 2 and 1) and room temperature graphite fluorides were studied by solid state NMR and NEXAFS. This latter synthesis allows the weakening of the C-F covalence by the coexistence of fluorinated carbon atoms having sp3 hybridization, and non-fluorinated sp2 one in the carbon layers (hyperconjugation) [1,2]. Data extracted from those two techniques are complementary providing information about the C-F bonding, weakened or pure covalent ones and the hybridization of the carbon valence states. Comparison of data obtained by different methods such as NMR, Raman and X-ray absorption results in a similar conclusion on the chemical bonding in fluorographites. The present works reviews all the possible configurations of fluorinated graphites, i.e. planar sheets with mainly sp2 hybridization in room temperature graphite fluorides and corrugated sheets with sp3 hybridization in covalent high temperature graphite fluoride. Different references such as highly oriented pyrolytic graphite (HOPG) crystal, graphitized carbon nanodiscs and nanodiamonds were also investigated for comparison.

[1] Y. Sato, K. Itoh, R. Hagiwara, T. Fukunaga, Y. Ito, Carbon 42(15) (2004) 3243.

[2] J. Giraudet, M. Dubois, K. Guérin, C. Delabarre, A. Hamwi, F. Masin, J. Phys. Chem. B 111(51) (2007) 14143.



253
Electrochemical properties of fluorinated graphitized carbon blacks
Yasser Ahmada, Elodie Disaa, Katia Guérina, Marc Duboisb, André Hamwib,*
a Institut de Chimie de Clermont-Ferrand UMR CNRS 6296 Clermont Université UBP
b Institut de Chimie de Clermont-Ferrand UMR CNRS 6296 Clermont Université UBP

Primary lithium batteries are commonly used for many applications thanks their numerous advantages such as high energy densities, good reliability, safety and long life. One of the attractive chemistries is that provided with a fluorine based cathode and more particularly carbon fluoride (denoted as CFx). The most important features of the Li/CFx batteries are: high energy density (up to 2203 Wh.kg−1), high average operating voltage (around 2.4 V vs. Li+/Li), long shelf life (>10 years at room temperature). However due to kinetic limitations associated with the poor electrical conductivity of strongly covalent CFx material, the battery can sustain only low to medium range of discharge currents that means low power densities. In order to develop such batteries with high power densities, the range of achievable discharge currents should be extended, in order to increase the power density. To address this issue, non-fluorinated parts should be present in the material to ensure the electronic conduction into the electrode, whereas fluorinated parts are insulating. Fast electron flux can be obtained and the power density is enhanced. In general, carbonaceous starting material has a strong effect on the electrochemical performances e.g. its nature, its morphology, its shape factor, the stacking of the graphene layers (in tubes or sheets). Researches about fluorination of carbonaceous nanomaterials must focus on the location of the fluorinated parts into the carbonaceous matrix. These parameters could act on the lithium and/or fluorine diffusion during the electrochemical processes. Moreover, fluorination conditions strongly influence the electrochemical performances. In particular, the choice of the fluorinating agent is of primary importance; atomic or molecular fluorine can be used [1,2].

This work focuses on the electrochemical performances of a particular fluorinated nanocarbons (graphitized carbon black GCBs) as electrode materials for primary lithium batteries. Two different strategies of fluorination have been applied on these materials in order to compare their power density and their thermal stability. The two fluorination methods applied to fluorinate graphitized carbon black materials were (i) the direct fluorination (under a flux of pure molecular fluorine) and (ii) controlled fluorination by thermal decomposition of a solid fluorinating agent, terbium tetrafluoride TbF4. Different electrochemical performances have been obtained, due to different fluorination mechanisms and thus different repartitions of the fluorinated and non-fluorinated domains in the carbonaceous lattice. The fluorination mechanisms of each type of fluorinated carbon have been established thank to a deep physical-chemical characterization by XRD, TEM, TGA and solid state NMR using 13C and 19F nuclei.

[1] Zhang W, Guérin K, Dubois M, Fawal ZE, Ivanov DA, Vidal L, et al. Carbon nanofibres fluorinated using TbF4 as fluorinating agent. Part I: Structural properties. Carbon. 2008;46(7):1010-6.

[2] Zhang W, Guérin K, Dubois M, Houdayer A, Masin F, Hamwi A. Carbon nanofibres fluorinated using TbF4 as fluorinating agent. Part II: Adsorption and electrochemical properties. Carbon. 2008;46(7):1017-24.



254
The effect of the graphite oxidation depth on the expanded graphite morphology and porous structure
Olga Shornikova, Ekaterina Kogan, Victor Avdeev
Lomonosov Moscow State University, Moscow, Russia 119991

Herein the transformation of structure, morphology and porosity observed during graphite chemical or electrochemical intercalation in nitric and sulfuric acids and further exfoliation was studied by scanning electron microscopy, contact angel measurements, X-ray diffraction, Raman spectroscopy, nitrogen adsorption etc. Natural graphite flakes was taken as a parent substance. Chemical intercalation was carried out in 98 % nitric and 96 % sulfuric acid to synthesize graphite nitrate and graphite bisulfate of different stages. Further chemical oxidation was conducted in the presence of oxidizer excess for 24-72 hours. Electrochemical intercalation was carried out by graphite anodic polarization in both concentrated and diluted (50 and 30 %) nitric and sulfuric acids at a constant current of 100 mA and specific quantity of electricity of 1000 – 3000 C/g. All the prepared samples were studied by XRD and then hydrolyzed to prepare expandable graphite. Expanded graphite was produced by the expandable graphite exfoliation at a temperature of 300 and 900 oC in air.
According to the XRD data and using Scherer equation, the graphite crystalline size along “c” axis was estimated for all the samples. The reduction of crystalline size from 120 nm for natural graphite to 40-60 and 10 nm during graphite intercalation was shown. The significant change was observed for electrochemically prepared samples especially in diluted nitric acid. Moreover, deeply oxidized sample are characterized with the lowering of the order between crystallines that is reflecting in the decreasing of the peaks intensity on XRD patterns and D-line appearance in Raman spectra. Exfoliation was shown not to affect the crystalline size.
Contact angel measurements shown that free surface energy for expanded graphite samples prepared by long-term chemical or electrochemical treatment is less than that for chemically prepared samples. Electrochemical samples demonstrate hydrophilic properties and could be wetted with polar liquids whereas chemically prepared samples are wetted only by non-polar liquids. The sorption capacity to water and octane was determined for the expanded graphite compacted to the pellets with a density of 0.3 g/cm3. The sorption rate along and perpendicular to the compacting axis was determined.
Specific surface area of expanded graphite samples varies from 20 m2/g to 160 m2/g. Porous structure of expanded graphite consists mostly of micropores and mesopores although in electrochemically prepared samples micropores was observed as well. The pore volume and pore size distribution was determined for all investigated samples.


255
Adsorption of Proteins by High Surface Area Carbons with Wide Porosity
Krisztina Lászlóa,*, Irina Savinab, Ajna Tótha, Erik Geisslerc, Lyuba Mikhalovskab, et al.
a Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, Budapest, Hungary
b Nanoscience & Nanotechnology Group, Faculty of Science and Engineering, University of Brighton, Brighton, United Kingdom
c 4Laboratoire Interdisciplinaire de Physique CNRS UMR 5588, Université J. Fourier de Grenoble,St Martin d'Hères, France

Porous carbons are used for purification of various bio-fluids, including for the treatment of acute poisoning by means of haemo-perfusion, whereby toxins are removed from the bloodstream by adsorption. In such processes the size of the pores relative to that of the proteins to be removed is of crucial importance, since many toxins are large molecules that cannot penetrate into micropores. For such molecules, carbons with larger pore size are required.

Here we report measurements of the adsorption of proteins on two microporous carbons of different pore size distributions, a resorcinol-formaldehyde based carbon aerogel (C1) [1, 2] and a porous MAST carbon made from phenolic resin (C2). The probe proteins, aprotinin and bovine serum albumin (BSA), are significantly different in molecular weight.

At saturation C1 adsorbs ca. 1.1 g/g aprotinin and 0.4 g/g BSA. In C2, the corresponding values are 0.27 and 0.09 g/g, respectively, in unbuffered conditions.

Small angle neutron scattering (SANS) was used to measure the penetration of these proteins into the two nanoporous carbons. In both systems the D2O solvent matched the signal from the carbon in the micro- and mesoporous q range. At small q, however, the signal of the D2O-filled samples displayed power law behaviour, I(q)~q-m, where m=4.8. This response is characteristic of interfaces that exhibit a concentration gradient normal to the surface. In other words, in the large pores, either owing to heteroatoms at the interface or to hydrophobicity, the liquid D2O is not in intimate contact with the carbon. When the proteins were present, however, this scattering component disappeared, indicating that the proteins make contact with the walls of the large pores.

In C1, the data suggest that the smaller protein forms spherical-like clusters of approximate radius 110 Å. In the C2 matrix, by contrast, the aprotinin assemblies are much larger (R≈700Å) and more polydisperse. In the higher q range, in addition to the surface scattering, volume scattering from the internal structure of the clusters becomes appreciable. Analogous results were found with BSA.

Acknowledgements. The support of the FP7 program 2009-269267 is gratefully acknowledged. We are grateful to the Institut Laue-Langevin for access to the neutron scattering instrument D11.

[1] K. László, O. Czakkel, G. Dobos, P. Lodewyckx, C. Rochas, E. Geissler Carbon 48, 1038-1048 (2010)

[2] K. László, O. Czakkel, B. Demé, E. Geissler Carbon 50, 4155-4162 (2012)



256
MOLYBDENUM DOPED CARBON AEROGELS WITH CATALYTIC ACTIVITY
Balázs Nagya, Dániel Ábraháma, Gábor Dobosb, Erik Geisslerc, Krisztina Lászlóa,*, et al.
a Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics, Budapest, Hungary
b Department of Atomic Physics, Budapest University of Technology and Economics, Budapest, Hungary
c Laboratoire Interdisciplinaire de Physique CNRS UMR 5588, Université J. Fourier de Grenoble, St Martin d'Hères, France

Carbon aerogels that are simultaneously micro-, meso- and macroporous offer advantages over other forms of porous materials for catalytic applications that demand rapid access to the internal surface. Polymer precursors for such carbons can be prepared from resorcinol and formaldehyde by a sol/gel process under controlled conditions. Carbonization enhances the microporosity while the porosity in the wider range is conserved [1, 2]. The synthesis route offers several opportunities for introducing metal ions that can improve the catalysis or gas purification efficiency of the porous carbon.

The precursor hydrogel was prepared by using sodium carbonate as catalyst. Drying was performed after substituting the water by acetone, which was then replaced with CO2 under supercritical conditions. A detailed description is given elsewhere [3]. The polymer aerogel was then impregnated with a solution of (NH4)6Mo7O24.4H2O and carbonized to yield carbon aerogels with highly dispersed molybdenum nanoparticles. The carbonization step reduced the Mo into various carbides.

The catalytic activity of the Mo decorated carbon aerogel was tested in the hydrogenation reaction of a model biomass. The molybdenum nanoparticles significantly reduced the amount of gaseous products (CO, CH4) and enhanced the yield of high value products such as acetone, acetaldehyde and ethyl acetate.

Acknowledgement

The support of the FP7 program 2009-269267 is gratefully acknowledged. The authors thank the ESRF for access to the French CRG beamline BM2.

References

[1] O. Czakkel, E. Geissler, I. M. Szilágyi, E. Székely, K. László, J. Coll. Int. Sci. 337, 513 (2009)

[2] O. Czakkel, K. Marthi, E. Geissler, K. László, Influence of drying on the morphology of resorcinol–formaldehyde-based carbon gels. Micropor. Mesopor. Mat. 86,124-133 (2005)

[3] C. Lin C, J. A. Ritter, Effect of synthesis pH on the structure of carbon xerogels Carbon 35, 1271-8 (1997)



257
Surface modification of MWCNTs with different surface chemistry during catalytic H2O2 decomposition
Ajna Tótha, Kateryna Voitkob, Berke Barbaraa, Gábor Dobosc, Krisztina Lászlóa, et al.
a Department of Physical Chemistry and Materials Science, Budapest University of Technology and Economics,Budapest, Hungary
b O.O. Chuiko Institute of Surface Chemistry of NAS of Ukraine, Kyiv, Ukraine
c Department of Atomic Physics, Budapest University of Technology and Economics, Budapest, Hungary

Owing to the expanding large-scale production from nanoindustry, incomplete combustion of fossil fuels and continuously growing motorization, carbon nanotubes (CNTs) are increasingly emitted into the environment. They are mobile, either air- or waterborne. They have been detected in air, water and soil phases even as far from any motorization as the polar region. The high surface area of CNTs raises concerns about their possible fate in nature.

Hydrogen peroxide is a well-known agent used in water purification and soil remediation because it is environmentally friendly and cheap. If CNTs are present when H2O2 assisted water or soil treatment is performed, being exposed to H2O2 and may act as a catalyst.

We investigated the effect of H2O2 decomposition on multiwall carbon nanotubes (MWCNTs) of different surface chemistry (untreated, O- and N-functionalised) but with similar morphology. It was found that the CNTs catalyse the decomposition of the peroxide and this effect is influenced by the surface chemistry of the nanotube. Surface analysis of the CNTs before and after such a reaction reveals that the chemistry of the nanotubes is modified during the catalysis resulting in the incorporation of more heteroatoms.

Acknowledgement:

The support of the FP7 Marie Curie IRSES program COMPOSITUM Hybrid Nanocomposites (PIRSES-GA-2008-230790) and Hungarian National Found OTKA (K101861) is gratefully acknowledged. We express our thanks to G. Bosznai for his assistance.

References:

1 I. Fekete-Kertész, M. Molnár, Á. Atkári, K. Gruiz, É. Fenyvesi: Hydrogen peroxide oxidation for in situ remediation of Trichloroethylene. Manuscript



262
Preparation of carbon nanomaterials from nature materials by hydrothermal carbonization
Yong Li, Lingpeng Yan, Yongzhen Yang, Xuguang Liu, Bingshe Xu
Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024, China

Hydrothermal carbonization is a simple and efficient method to prepare inorganic materials. The carbon nanomaterials were prepared by hydrothermal carbonization of natural products such as leaf and tea in certain conditions. The effect of various reaction parameters on morphology, such as reaction time and temperature, was evaluated. The microstructure and functional groups were characterized using field emission scanning electron microscopy, X-ray diffraction, thermogravimetric analysis and Fourier transformation infrared spectrometry. This work provides a wide route toward the preparation and applications of carbon nanomaterials from nature materials.



263
Preparation of iron/graphene nanocomposites by DC arc discharge and their characterization
Fan Zhang, Shen Cui, et al.
Tianjin University

Iron compounds/graphene nanocomposites (ICs/GNCs) are one of the novel trends in the research field of graphene and have many applications in extensive areas [1]. Several methods have been reported for preparation of ICs/GNCs, such as chemical deposition, hydrotherm, and direct pyrolysis [2–4]. No iron/graphene nanocomposites (Fe/GNCs) have been reported, except graphene-encapsulated iron microspheres/graphene nanocomposites [5]. Here we present the preparation of Fe/GNCs by DC arc discharge under nitrogen atmosphere of high temperature, using an anode with high iron content (72.8 mass %). HRTEM characterization clearly shows that iron species mainly exists in the form of the quasi-spherical nanoparticles with diameters of 3-6 nm inside graphene. HRTEM and SEM characterizations show that the Fe/GNCs are the main component in the inner core of cylinder-shaped deposit (ICCSD) formed on the top of the cathode. The Raman spectrum of the sample of ICCSD shows the characteristic peaks of the multi-layer graphene nanosheets. XRD and XPS characterizations show that the phase composition of the sample of ICCSD includes carbon, iron, iron carbide, ferrous and ferric oxide, iron nitride, and carbon nitride. The sample of ICCSD shows the superparamagnetic behavior and its saturation magnetization is 164.45 emu/g. The formation mechanism of Fe/GNCs may mainly include three steps, i.e., (a) the formation of carbon atoms and iron atoms and/or clusters, (b) the formation of graphene nuclei, and (c) Fe species is incorporated into the graphene to form Fe/GNCs.

References

[1] H.K. He, C. Gao, Supraparamagnetic, conductive, and processable multifunctional graphene nanosheets coated with high-density Fe3O4 nanoparticles, ACS Appl Mater Inter 2 (11) 2010, p. 3201-3210.

[2] B.J. Li, H.Q. Cao, J. Shao, M.Z. Qu, J.H. Warner, Superparamagnetic Fe3O4 nanocrystals@graphene composites for energy storage devices, J Mater Chem 21 2011, p. 5069-5075.

[3] G. Wang, T. Liu, Y.J. Luo, Y. Zhao, Z.Y. Ren, J.B. Bai, H. Wang, Preparation of Fe2O3/graphene composite and its electrochemical performance as an anode material for lithium ion batteries, J Alloys Comp 509 2011, p. L216-L220.

[4] J.S. Zhou, H.H. Song, L.L. Ma, X.H. Chen, Magnetite/graphene nanosheet composites: interfacial interaction and its impact on the durable high-rate performance in lithium-ion batteries, RSC Adv 1 2011, p. 782-791.

[5] P. Guo, G. Zhu, H.H. Song, X.H. Chen, S.J. Zhang, Graphene-encapsulated iron microspheres on the graphene nanosheets, Phys Chem Chem Phys 13 2011, p. 17818-17824.



264
Particle size effects on adsorption behaviors of molecularly imprinted polymers on the surface of porous carbon microspheres
Lei Qin, Sha Li, Yongzhen Yang, Husheng Jia, Xuguang Liu, et al.
Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024, China

The environmental-friendly reagent glucose was used as carbon source to prepare the porous carbon microspheres (PCMSs). The size-controllable PCMSs can be obtained by changing the original concentration of glucose and time span of synthesis through the hydro-thermal synthesis methods. Three groups of PCMSs in different sizes were selected to prepare the molecularly imprinted polymer (MIP) in various particle sizes. Dibenzothiophene (DBT) was used as the template molecule so that the product can be applied in selective removal of DBT from gasoline. Field emission scanning electron microscopy, thermogravimetric analysis, Fourier transformation infrared spectrometry and nitrogen adsorption measurement were used to characterize the morphology and structure of MIP. The selective adsorption ability of MIP was detected by gas chromatography as well as adsorption kinetics and isotherms. Additionally, adsorption behaviors including dynamic adsorption and regeneration were also tentatively investigated. The research provides a basis for gaining high perfermance adsorption material for deep desulphurization of fuel oils.



265
Synthesis and fluorescence properties of carbon quantum dots
Xiaoting Feng, Sha Li, Yongzhen Yang, Lanqing Hu, Xuguang Liu, et al.
Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024, China

Water-soluble fluorescent carbon quantum dots (CQDs) were synthesized by a simple hydrothermal process with glucose as carbon source and water as solvent. In order to improve its fluorescence properties, CQDs were passivated by polyethylene glycol (PEG200N). Then the effects of glucose concentration, dosage of passivating reagent, passivation time and temperature on the fluorescence intensity of passivated CQDs were investigated. High resolution transmission electron microscopy and Atomic force microscope were used to characterize the morphology of the passivated CQDs. Ultraviolet irradiation and fluorescence spectrophotometry were used to investigate fluorescence properties.



267
Advanced Chemical Modifications of Graphene
Mikkel Kongsfelta,*, Andrew Cassidyb, Louis Nilssonb, Liv Hornekærc, Kim Daasbjerga, et al.
a Department of Chemistry and iNANO, Aarhus University
b Department of Physics and Astronomy, Aarhus University
c Department of Physics and Astronomy and iNANO, Aarhus University

Introduction

Since the discovery of graphene as a stable 2D material in 2004[1], the interest in this material and its unique properties has exploded. Great challenges remain, however, and prevent the implementation in real applications. To exploit graphene in real world electronics detailed control of the charge transport, band gap and positioning of graphene on a substrate are a few of the challenges. For coating applications, it also remains unsolved how to improve the adhesion of graphene to a substrate as well as producing large sheets in a high enough quality.

Chemical Modifications Could Be the Answer

One of the many proposed approaches for solving these issues is controlled chemical modifications of graphene[2]. The main focus of chemical modifications has been on graphene oxide, whereas limited knowledge is available about chemical reactions using prisitine graphene. Hydrogenation of graphene has been shown to introduce a bandgap in graphene on iridium suitable for applications in transistors[3]. Aryl diazonium salts has been shown in certain cases to react primarily on edges of graphene and to be selective towards single layers of graphene[4]. These are a few very promising examples of how chemical modifications of graphene could be utilized to control this interesting carbon material.

It is well known now, that the substrate for the graphene has an enormous impact on the properties of graphene and thereby also on the reactivity. Very few studies, however, have addressed or even discussed these implications in the studies of chemical reactions with graphene.

In our work, we utilize the reactivity of aryl diazonium salts to modify graphene on a range of metal substrates such as platinum, iridium and nickel. We use graphene grown directly on single crystals of transition metal substrates to gain a high degree of control. Using Scanning Tunneling Microscopy (STM), Raman spectroscopy and Temperature-Programmed Desorption (TPD), we are able to make detailed analysis of the reactions of aryl diazonium salts made on graphene substrates. These results are giving a new insight into the reactivity of prisitine graphene on a range of substrates. Utilizing studies of these reactions under Ultra High Vacuum (UHV) conditions, our work is contributing to the field with knowledge that will enhance the prospect of doing controlled chemical reactions on graphene.

References

[1] Novoselov KS, Geim aK, Morozov SV, Jiang D, Zhang Y, Dubonos SV, et al. Electric field effect in atomically thin carbon films. Science (New York, NY). 2004;306:666-9.

[2] Yan L, Zheng YB, Zhao F, Li S, Gao X, Xu B, et al. Chemistry and physics of a single atomic layer: strategies and challenges for functionalization of graphene and graphene-based materials. Chemical Society reviews. 2012;41:97-114.

[3] Balog R, Jørgensen B, Nilsson L, Andersen M, Rienks E, Bianchi M, et al. Bandgap opening in graphene induced by patterned hydrogen adsorption. Nature materials. 2010;9:315-9.

[4] Sharma R, Baik JH, Perera CJ, Strano MS. Anomalously large reactivity of single graphene layers and edges toward electron transfer chemistries. Nano letters. 2010;10:398-405.



269
Binderless thin films of zeolite-templated carbon on a conductive substrate for high performance super capacitors
Ángel Berenguer-Murciaa,*, Hirotomo Nishiharab, Emilia Morallóna, Takashi Kyotanib, Diego Cazorla-Amorosa, et al.
a University of Alicante
b Tohoku University

One of the challenges that still remains for the development of next-generation electrochemical capacitors is the preparation of capacitor electrodes with high rate performance, or in other words, which can store energy even under high charge-discharge rates. Even though significant advances have been made in the preparation of carbon materials for the fabrication of electrodes with enhanced performance, be it either from a classical approach (activated carbons) or from a more recent approach (ordered porous carbons with tunable porosity, including ordered mesoporous carbons and zeolite templated carbons (ZTCs)). Nevertheless, all these materials are prepared in powder form, and in most cases, the obtained powders possess very small particle size. The use of such materials for capacitors implies that a binder such as PTFE is required in order to prepare a continuous layer which may be shaped for its use as electrode. This brings forth the significant disadvantage that interparticle resistance between the active material and the binder may be too high, which in turn may result in poor performance of the electrode under fast charge-discharge conditions. This work focuses on the integration of electrochemical and chemical techniques for the development of supercapacitors with high rate performance based on thin zeolite templated carbon layers supported on a macroporous current collector. Using a suspension of FAU zeolite crystals with an average size of 50 nm, we have prepared controlled zeolite deposits on macroporous carbon discs by means of electrochemically assisted deposition. The prepared deposits are firmly anchored to the support surface (they could not be removed after sonication for 15 minutes in an ultrasonic bath) and can be readily used as templates for the direct preparation of ZTC layers by chemical vapour deposition at 600ºC using a stream of 15% C2H2 in N2 with a flow rate of 150 sccm, as reported elsewhere. The prepared materials are then washed with 20% HF overnight to yield the macroporous carbon support coated with a thin layer of ZTC firmly anchored to its surface which may be used as electrochemical capacitor electrodes without any further preparation. The prepared materials were analyzed by SEM and TEM to reveal that the zeolitic structure could be successfully replicated even when prepared in a thin layer configuration. The resulting thin films were electrochemically characterized in a three-electrode cell by cyclic voltammetry at different scan rates (from 1 to 500 mV/s) and galvanostatic charge-discharge experiments using different current densities in 1 M aqueous H2SO4. Our results clearly show that even under the fastest scan rates used (500 mV/s), the shape of the obtained voltammograms retains the characteristic square shape of a double layer process, which even displays noticeable redox processes due to the pseudocapacitance, arising from the surface functional groups present on the ZTC layer. This behavior evidences the negligible interparticle resistance of the obtained film, and thus the prepared material should be very interesting for the development of electrodes for high energy density capacitors.



273
Elucidation of Surface Properties on Carbon Blacks by Solid-State NMR Using Water Molecule as a Surface Probe
Hata Koichiroa, Ideta Keiko Idetab, Miyawaki Jin Miyawakib,*, Mochida Isaoc, Yoon Seong-Hod, et al.
a Interdisciplinary Graduate School of Engineering Sciences, Kyushu University
b Institute for Materials Chemistry and Engineering, Kyushu University
c Research and Education Center of Carbon Resources, Kyushu University
d Interdisciplinary Graduate School of Engineering Sciences, Kyushu University. Institute for Materials Chemistry and Engineering, Kyushu University

Carbon blacks (CBs) are mainly used to reinforce tire rubbers. Particle size and surface functionalities are known to strongly influence on contact characteristics between CBs and rubbers, which control the tire performance. In this study, we tried to elucidate surface properties of CBs by applying solid-state NMR technique using adsorbed water as a surface probe, which can give rise to information about states of adsorbed molecules. Amounts of functionalities were changed by O3 oxidization or reductive heat treatment. Elemental compositions of samples were analyzed by a CHN analyzer. N2 isotherms at 77 K and H2O isotherms at 303 K were measured using a volumetric adsorption equipment. Prior to NMR measurements, CBs were dried at 373 K in a N2 flow for 2 h. Then, the dried CBs were exposed to vapors of H2O/D2O mixtures of different mixing ratios at 298 K for 96 h. Solid-state 1H-NMR measurements were carried out using 400 MHz NMR equipment at a magic angle spinning (MAS) speed of 5 or 10 kHz. Oxygen contents of the samples increased by the oxidization, and decreased by the reductive heat treatment. The specific surface area by analysis of N2 adsorption isotherms did not show remarkable changes regardless of the oxidation or reduction treatment. The 1H-NMR spectra of dried CBs showed a weak broad peak centered at about 0 ppm and ranging from -20 to 20 ppm, which was likely to be attributed to protons of remained volatile matters on the CBs. For oxidized CB, another weak broad peak, considered to be originated from the introduced surface functionalities, was observed at about 6 ppm. In 2H-NMR spectra, no apparent peaks were observed for all dried CBs. Water-adsorbed CBs gave relatively strong and broad peaks centered at about -5 ppm at 5 kHz of MAS speed. When the MAS speed increased to 10 kHz, intensity of the broad peaks decreased and new sharp peaks appeared at low magnetic field at 4-5 ppm. The new peaks were considered to be due to water molecules desorbed by very high speed MAS, and thus the broad peaks were able to be assigned to weakly adsorbed water on the CB surface. Depending on the amount of oxygen content, the extent of the intensity decrease of the broad peaks was different; the more the oxygen content, the less the intensity decrease. On the other hand, a sharp peak at 3-4 ppm observed in 1H-MAS NMR spectrum of water-adsorbed oxidized CB was not found in 2H-MAS NMR spectrum. Because a very broad characteristic peak was observed in 2H-NMR spectrum at the static condition, the broad peak at 3-4 ppm should be due to water molecules strongly adsorbed to surface functionalities. Remarkably short spin-lattice relaxation time of this peak supported the assignment. These suggest that, by combined usage of 1H- and 2H-NMR measurements with changing the MAS speed, it could be possible to classify adsorbed waters depending on the adsorption strength, and thus information about different surface properties of CBs would be obtainable.



274
Producing of hydrophobic sand from superhydrophobic soot synthesized in flames
Bakhytzhan Lesbayev, Meruyert Nazhipkyzy, Milana Solovyova, Nikolay Prikhodko, Gauhar Smagulova, et al.
Institute of Combustion Problems

The paper presents results of studies of the synthesis of carbon soot which has superhydrophobic properties in propane - oxygen flame on the surface of the nickel substrate as well as hydrophobic sand from this soot producing. Propane flow rate ranged from 50 to 150, the oxygen from 260 to 310 cm3/min. Substrate is a circle with a diameter of 7 cm, which is located at a height of 2-3 cm above the flame. The time of deposition of soot particles on the substrate surface from 4 to 10 minutes. The soot layer thickness deposited on the substrate surface is 1 - 1.5 mm. The studies carried out with help of liquid droplet method showed that the contact angle of the surface of carbon soot is over 1600C, which characterizes its superhydrophobic properties. Electron microscopic studies showed that soot surface consists of soot particles with sizes of 30-50 nm, joined together in the form of pearl, which preserving the structure of the pearl after the forced wetting in an alcohol solution and mechanical treatment.

Synthesized superhydrophobic soot used to produce of hydrophobic sand. Hydrophobic sand production technology involves several phases. On the surface of sands the glutinous agent is applying and on applied glutinous agent the nanosized superhydrophobic layer of soot is attaching and within 1 hour the process of hardening is occurring. In the course of the experiment the normal washed river sand and as glutinous agent the polyurethane glue dissolved in ethyl acetate were used.

Thus the method of synthesis of soot which has superhydrophobic properties by propane combustion was worked out. With employment of synthesized soot the hydrophobic sand was produced. The proposed method allows to hydrophobize not only the surface layer of sands, but the whole mass of the volume of sand, which significantly improves the quality of protection against the penetration of moisture. The produced hydrofobic sand is proposed to use in agriculture to prevent leakage of irrigation water to the lower layers of the soil or evaporation. Hydrophobic sand can also be used to isolate the soil around the plants from saline soils and saline groundwater, leading to the destruction of the root system of plants.



276
NMR Analysis of Water Adsorption Behavior in Carbon Micropores
Hata Koichiroa, Ideta Keikob, Miyawaki Jinb,*, Mochida Isaoc, Yoon Seong-Hod, et al.
a Interdisciplinary Graduate School of Engineering Sciences, Kyushu University
b Institute for Materials Chemistry and Engineering, Kyushu University
c Research and Education Center of Carbon Resources, Kyushu University
d Interdisciplinary Graduate School of Engineering Sciences, Kyushu University,Institute for Materials Chemistry and Engineering, Kyushu University

Adsorption behavior of water molecules in carbon micropores are interested in various aspects, such as biochemistry, fundamental science, and industrial applications. In this study, we tried to analyze adsorbed states of water molecules in micropores of carbon materials by solid-state NMR method. Various porous carbons were prepared by KOH or steam activation and reductive heat treatment using non-porous carbon black as a parent material. NMR measurements were carried out for the samples, which had been exposed to vapors of H2O/D2O mixtures of different mixing ratios at room temperature, using a 400 MHz solid-state NMR equipment at different magic angle spinning speeds. It was found that adsorbed waters in carbon micropores showed NMR peaks at different chemical shifts as compared with those on the external surface in both 1H- and 2H-NMR spectra. The chemical shift of the adsorbed waters in carbon micropores depended on activation methods and conditions. Furthermore, by comparison of the 1H- and 2H-NMR spectra, influence of surface functionalities was also able to be estimated. These findings suggest that the NMR technique is a powerful tool to analyze adsorption behavior of water molecules in carbon micropores.



279
Selective conductivity of quartz grains modified by carbon
Tatyana Shabanovaa,*, Nina Mofab, Zulkhair Mansurovb, Udana Koshimovab
a K.I.Satpaev Institute of geological sciences
b Institute of Combustion Problems

Quartz sand after mechanochemical processings with carbon containing the modifier gets the selective raised or lowered dielectric permeability. The appearing through electronic microscopy (JEM – 100CX, 100 kV) fixes various morphological structures of carbon -quartz composites. Diffraction analysis has revealed structural orderliness in these particles. Reception of various materials for condensers is possible at modifying natural quartzes.


References
1.Mansurov Z.A., Mofa N.N.,Shabanova T.A. Mechanochemical treatment of mineral materials with carbon-containing modifiers. // Carbon 12, 15-25 julay 2012, Kracov, ID 770, CD.
2. Solodovnic V.D. Mikrokapsulirovanie. - M: Chemistry. 1980. - 216 p.



280
Quantum chemical properties of graphene nanoflakes
Mykola Kartel, Oksana Karpenko, Viktor Lobanov
Chuiko Institute of Surface Chemistry, NAS of Ukraine

Properties of carbon nanoclusters (CNC) graphene-like structure depend on both the form and the type of framed boundaries. The most interesting are zigzag type boundaries of CNC, so for their doubly coordinated atoms (C(2)) are localized edge states with main input from the dangling sp2-hybrid orbitals. The energies of these states are into the area of ​​the energy spectrum for highest occupied molecular orbitals (MO).

The report presents the results of the calculation (the DFT method, the exchange-correlation functional B3LYP, basis 6-31 G**) of geometric and electronic properties of hexagonal CNC C24 - S216. Optimization of their spatial structure of a given multiplicity (M) showed that the ground electronic state (GES) of CNC C24 is a singlet, and for others the most stable high-spin states are triplet and quintet.

As the majority of the properties for all investigated CNC are almost independent from their size, they are convenient to consider the one representative, namely C96. An equilibrium geometry of CNC C96 (M = 5) is characterized by the formation of six C≡C bonds (1.236 Å) at the junction of zigzag-like edges, and the presence on its perimeter conjugated system weakly interacted with the 2pz-orbitals of the central part of the cluster. This is indicated by the length of the corresponding C-C bonds, which range from 1.484 to 1.452 Å and significantly higher than the bond length in benzene. Despite the fact that the CNC C96 is composed from atom of only one type, the distribution of molecular electrostatic potential for GES of C96 (M = 5) in a neighborhood is far from uniform.

Analysis of the structure of MO α- and β-subsystems showed that the lowest vacant MO were located above occupied, were delocalized across the cluster. MO of the same type (vacant), falling in the range of energies occupied MO are distributed solely on the periphery of the cluster and focused on the triple and almost double bonds of edge cyclic chain. Therefore, the filling of such MO eliminates the possibility of localization of the electronic states on uncompensated bonds of atoms C(2). Each of the frontal occupied MO are almost 100% focused on one of the edges of the CNC C96. It has a rather complicated topology and ensures implementation in the system of edge states localized on uncompensated bonds.

GES of CNC C24 is singlet that can be explained by the presence of only two carbon atoms in each of the six boundaries, and for CNC C54 is triplet, which is also due to the number of atoms C(2) in each of the boundaries, which equals three. In the CNC C96 each of boundaries contains four atoms C(2). On two of them, not involved in the formation of triple bonds, the spin densities are of the same sign, which generates ferromagnetic ordering of the corresponding magnetic moments within each of the boundaries. Similarly, we can explain the triplet GES of CNC C150 and quintet GES of CNC C216, each of boundaries of which has respectively odd and even number of carbon atoms C(2).



281
Urease-like properties of nanoscale sp2-hybridized carbon materials
Mykola Kartel, Katerina Voitko, Olga Bakalinska, Dmytro Nasiedkin, Borys Palyanitca, et al.
Chuiko Institute of Surface Chemistry, NAS of Ukraine

Application of extracorporeal methods for blood toxic substances neutralization makes it possible to correct process of nitrous metabolism, in particular, synthesis and decomposition of urea. The materials with own urease-like activity could solve this problem. Among them the nanoscale carbon materials appear as perspective. Such materials, first of all, carbon nanotubes (CNTs), fullerenes, nanoplates of exfoliated graphite (GNPs) and graphene, take a key position among nanomaterials that could be used in medicine.

In this study the enzymatic (urease-like) catalytic properties of CNTs and GNPs were investigated in urea hydrolysis reaction by volumetric method. An influence of surface chemistry (O-, N- and S-atoms doping), concentration of urea and pH on catalytic properties of mentioned before carbon were determined. Michaelis constants (Km, mmol) have been applied for analysis, the quantitative assessment and comparison of catalytic activity of investigated carbon materials and their modified forms. Affinity constant (Kaff.) is a value inverse to Km and it was applied for simplification of results interpretation.

Initial multi-walled carbon nanotubes were prepared by CVD-method at catalytic decomposition of propylene. CNTs correspond to requests of Ukrainian Standard (TU U 24.1-03291669-009:2009). For further investigation CNTs were oxidized (70% HNO3, 95 - 100 oC, 3 h, O-CNTs) and doped by nitrogen using thermal treaty process with urea (700-800 oC, 1 h in Argon, N-CNTs). CNTs were also modified by SO3H--groups (S-CNTs): О-CNTs were treated by concentrated H2SO4 (250 - 300 oC, 6 h). GNPs samples were prepared from exfoliated graphite, which in turn was produced from intercalated graphite by thermal shock at 900 oC for 10 s. GNPs were oxidized for 6 h in the mixture of concentrated sulphuric and nitric acids for getting O-GNPs; oxidized samples were doped by nitrogen using urea melt (like for N-CNTs) to obtain N-GNPs.

Synthesized materials were characterized by several methods: Boehm titration, TPD MS analysis, hydrophilicity degree by determination of contact angles, and structural characteristics by X-ray diffraction.

It was shown that urease-like activity of carbon nanomaterials is more stable than native enzyme for high substrate concentrations. Thus, investigated nanomaterials are perspective for biomedicine usage. It was established that activity of CNTs and S-CNTs practically does not depend from рН. Kaff for these materials are two times lower than N-CNTs and О-CNTs. The catalytic activity of O- and N-doped CNTs is extreme like urease activity with maximum at рН 6.7 for N-ВНТ and pH 7.2 for О-CNT. It should be mentioned that activity of O- and N-doped CNTs are higher than native enzyme at pH 7.1 - 7.3.

The catalytic activity of О-GNPs is less than native urease and extremely depends from pH with maximum at рН 7.2. It is remarkable that at pH 8 activity of N-GNPs two times more than urease (due to its alkaline inhibition). The obtained results of this study can be used for creation selective biosensors and biocatalysts, processes of separation, enzyme immobilization, drug delivery, etc.



284
Rheological characterization of petroleum pitches
Fabiana Louvema,*, Carlos Henrique Dutraa, Paulo Mendesb, Luiz Castroa
a NCDTC/CTEx
b PUC-Rio

The rheological properties of petroleum pitches are very important during the manufacturing process of carbon materials regarding to the final properties of the carbon products, especially during the mesophase formation. In this work, three pitch samples with mesophase contents between 10% and 92% were obtained from FCC decant oil with different heat treatment time and were analyzed in a rotational rheometer using a plate/plate geometry. The rheological behavior of these pitches was studied using steady and transient shear rheometry. The viscoelastic behavior of the pitches was investigated using oscillatory rheometry and creep-recovery tests.



289
Super-structured Carbon for Energy Storage
Feiyu Kang
Tsinghua University

Carbon is usually used in energy storage and conversion devices due to their good electric conductivity, low cost, easy to control the structure and surface functionality. However, a pure carbon material cannot achieve both energy density and power density. We propose a super-structured carbon model to reach superior properties. This model demonstrate a super-structure carbon possesses three levels nano-structures, 1) surface functional group and graphitation degree control for wetting with electrolyte and high conductivity; 2) Hierarchical pore structure for charge storage and transportation; and 3) composite with non-carbons to enhance energy and power densities.

We will present several examples to demonstrate the methodology: 1) MnO2 loading on the carbon nano-fiber (CNF) prepared by electric spinning process for the super-capacitor; 2) Tin or silicon particles dispersed inside CNF for anode materials in lithium ion battery (LIB); 3) metal oxides composite with graphite nano-sheet using for electrodes both in LIB and super-capacitor; 4) graphitic porous carbon prepared with asphalt using for electrodes in asymmetric super-capacitors.



290
Fracture Properties of Kerogen and Importance for Organic-Rich Shales
Laurent Brocharda,*, György Hantalb, Hadrien Laubieb, Roland J.-M. Pellenqb, Franz J. Ulmb
a Université Paris-Est, Laboratoire Navier (UMR 8205), CNRS, ENPC, IFSTTAR, F-77455 Marne-la-Vallée
b MIT, Civil and Environmental Engineering, 77 Massachusetts avenue, 02139,Cambridge, MA, USA

Oil and gas produced from organic-rich shales have become in the last ten years one of the most promising sources of unconventional fossil fuels. The oil and gas are trapped in rocks of very small permeability, but hydraulic fracturing enables to operate those reservoirs with competitive costs. The global reserves of shale oil and gas that are potentially recoverable are equivalent to tens of years of world consumption. However, hydraulic fracturing is facing many challenges regarding the productivity but also the security and the environment. One of those challenges is to understand how the fractures propagate underground. The propagation depends on the mechanical stress prevailing in the reservoir and on the fracture properties of the rocks. Regarding the fracture properties, the oil and gas industry developed brittleness indicators to distinguish between brittle rocks (containing mostly calcite and silica) and ductile rocks (containing a significant proportion of clay and kerogen). During fracturing, a brittle rock shatters easily leading to a well-distributed network of fractures, whereas a ductile rock deforms instead of shattering leading to few fractures and in some situations acting as a barrier to the fracture propagation. In this work, we study the role of kerogen in the ductility of shale. The ultimate objective is to develop a fine understanding of the fracture properties of shales.

Organic-rich shales are heterogeneous materials containing a small fraction of kerogen. The typical size of the kerogen heterogeneities is a micrometer or less, and, therefore, mechanical testing on these materials are usually performed at the scale of the heterogeneous medium. Measuring the fracture properties of kerogen and of its interface with minerals is very challenging. As an alternative to laboratory experiments, we use molecular simulations to estimate fracture properties at the nanometer scale. First, we develop a methodology to estimate fracture properties by molecular simulation. This methodology is a thermodynamic integration based on the energy approach of fracture mechanics. We validate the methology on the specific case of silica, a very brittle mineral common in shales, for which experimental data are available and the classical theory of Linear Elastic Fracture Mechanics (LEFM) is valid. Then, we apply the methodology to a microporous carbon, which is a rough representation of kerogen at the molecular scale. We identify a significant ductility and we show that LEFM could not apply to kerogen at least at the nanometer scale. Finally, we reconstruct the silica-kerogen interface based on a study of the interface chemistry by quantum calculation. We estimate the fracture properties of the reconstructed interfaces and, as for bulk kerogen, we identify a significant ductility. The ductility comes from the cross-linked carbon structure of kerogen that can rearrange locally in the microporous space, which dissipates a lot of energy. Those results at the scale of the constituents of shales and their interface can be combined to predict the effective fracture properties of the heterogeneous shale. We present some cases, which show that a small fraction of kerogen can turn a brittle mineral matrix into ductile heterogeneous shale.



293
The Effects of Graphene as a Conductive Material for Capacitive Deionization Application
Ayu Tyas Utami Nugrahennya, Jiyoung Kima, Seongyop Limb, Sangkyung Kimb, Doo-Hwan Jungb,*, et al.
a Advanced Energy Technology, University of Science and Technology (UST), 305-343 Daejeon, South Korea
b Fuel Cell Research Center, Korea Institute of Energy Research (KIER), 305-343 Daejeon, South Korea

Graphene has attracted many interests because of its excellent properties. This paper report the addition effect of graphene as conductive material in the electrode composition of capacitive deionization (CDI), a process to remove salt from water using adsorption and desorption technique driven by external applied voltage. Graphene can be synthesized in an inexpensive way from the reduction of graphite oxide (GO) by removing the oxygen-containing groups with the recovery of a conjugated structure. GO powder can be obtained from the modification of Hummers method and reduced into graphene material using thermal method. The physical and electrochemical characteristics of graphene material were evaluated and its desalination performance test was carried using a series of CDI unit cell with a potentiostat and conductivity meter by varying the feed rate and concentration of the salt solution. The salt removal efficiency was compared with that of carbon black as conductive material in a CDI electrode.



294
Tribologic properties of exfoliated graphite in the presence of lubricating base oil.
Audrey MOLZAa, Jean-Louis MANSOTb,*, Yves BERCIONc, Georges MINATCHYa, Laurence ROMANAa, et al.
a GTSI Université des Antilles et de la Guyane
b GTSI and C3MAG Université des Antilles et de la Guyane
c C3MAG Université des Antilles et de la Guyane

In order to overcome the limitations of molecular anti wear and friction reduction additives used in lubrication oils and greases, new lubrication strategies, using solid nano particles as nano additives, were recently developed [1,2]. The present work is concerned with the tribologic properties of nano particles of exfoliated graphite used as solid lubricant (deposited on the sliding surfaces) and dispersed in the lubricating base oil presenting a low viscosity (pentane, dodecane). As for molecular additives, the friction reduction process is associated to the formation of a tribofilm between the rubbing surfaces [2]. When the exfoliated graphite particles are used as solid lubricant, the recorded friction coefficient is of 0.08. When they are dispersed in the base oil the friction coefficient drastically decreases down to 0.03. In order to understand the friction reduction mechanisms in the two cases, the structure of the resulting tribofilms, formed during friction, are investigated by analytical transmission electron microscopy, electron diffraction and Raman micro-spectrometry. When exfoliated particles are used as solid lubricants, the tribofilm presents a ill organised structure mainly constituted nano crystallized domains (≈2nm average diameters) embedded in an amorphous carbonaceous phase. When the particles are in dispersion in the lubricating base oil, the tribofilm is constituted of large lamellar particles oriented parallel to the sliding plane. For this last case, in situ Raman analyses carried out in the dynamic contact allowed us to point out the simultaneous presence of the base oil and the graphite nano particles in the contact which induces both the resulting well organised structure of the final tribofilm and the drastic friction reduction.

ACKNOWLEDGEMENTS

The authors acknowledge the French research department, the Conseil Régional de la Guadeloupe, the Fond Social Européen (FSE) and Fonds Européens de Développement Régional (FEDER) for their financial supports.

[1] J.L Mansot, M. Hallouis and J.M Martin, Colloids and Surfaces A, 75, (1993), 25

[2] J.L. Mansot, J.M. Martin, Y. Bercion, L. Romana, “Nanolubrication”, Brazil. J. of Phys., 39, 1, (2009), 53



295
Phenolic resin-based carbon/reduced graphene oxide composite ultrafine fibers by electrospinning for adsorption of water and volatile organic compounds
Zheng-Hong Huanbg, Yu Bai, Feiyu Kang
School of Materials Science and Engineering, Tsinghua University

Flexible carbon/reduced graphene oxide (RGO) composite ultrafine fibers were prepared from resole-type phenolic resin and graphene oxide (GO) by electrospinning, and their adsorption performance for water and volatile organic compounds (VOCs) was evaluated. Hydrogen bonds between GO sheets and phenolic resin demonstrated contributed to the stable network structure and flexible freestanding characteristic of carbon/RGO composite fibers. Nitrogen adsorption measurement showed that the specific surface area and pore volume of pristine carbon and composite fibers were extremely similar. Water contact angles and adsorption isotherms suggested that improved hydrophobicity was observed with carbon/RGO composite fibers due to the embedded RGO and more micropores with widths of 1.4-1.5 nm.



296
Electrical Impedance of Reduced Graphene Oxide Multilayers
Marcos Grossa,*, Leonardo Paternob, Mauro da Silvac, Marcelo Pereira-da-Silvad
a Universidade de Brasilia - Instituto de Quimica
b Universidade de Brasilia - Instituto de Química
c Pontificia Universidade Catolica de SP
d Universidade de Sao Paulo - Instituto de Fisica de Sao Carlos

Reduced graphene oxide (RGO) multilayers were deposited onto plain glass slides and gold interdigitated microelectrodes following a layer-by-layer assembly procedure and their electrical properties were investigated by means of impedance spectroscopy. The multilayer deposition was performed in the electrostatic mode, where a solid substrate is alternately immersed in cationic and anionic solutions. For that purpose, poly(diallyldimethyl ammonium) chloride (PDAC) in aqueous solution was used as a polycation and graphene oxide (GO) in aqueous suspension (pH 9) was used as an anion. Multilayered films of type (PDAC/GO)n where n stands for the number of PDAC/GO bilayers were deposited with n varying from 1 to 20. Monitoring of film assembly by UV-vis spectroscopy and AFM revealed, respectively, that the transparency of reduced films decreases while their thickness increases practically linearly with the number of bilayers. For instance, each PDAC/GO bilayers displays thickness of 1.4 nm. Thus, this deposition procedure enables one to control the film growth in the nanometer range by simply varying the number of deposition cycles (n). The thicker multilayers (n = 10 and 20) appeared pale yellow while the thinner ones were practically colorless. After chemical reduction with a hot aqueous hydrazine solution all multilayers turned dark. Raman spectra confirmed the reduction reaction by the increase on the ID/IG ratio (ratio of intensities of D-band and G-band in graphene) in the samples. Impedance spectra of multilayers deposited onto interdigitated microelectrodes before chemical reduction confirmed the insulating behavior, with an overall impedance of 105 ohms (at 20 Hz) which decreased continuously as the frequency increased up to 10 MHz. After chemical reduction, the overall impedance (at 20 Hz) decreased to 190 ohms (about 3 orders of magnitude lower) and a single relaxation process was detected solely above 105 Hz, which confirms the conversion from GO to RGO. Furthermore, it was also observed an asymptotic decrease on the impedance of reduced multilayers when going from 1 to 20 PDAC/GO bilayers. This behavior is ascribed to the densification of the multilayer as the number of bilayers increases. In conclusion, the multilayer assembly procedure described herein offers a simple but very efficient way to process graphene-based materials with great control over multilayers' structure and end properties and which make them promising electrode materials for optoelectronic devices.



297
Multilayered Nanocomposites of Graphene-Oxide and Magnetite Nanoparticles
Camila Costaa,*, Leonardo Paternob, N Pereiraa, Maria Solerc, Mauro da Silvad, et al.
a Universidade de Brasilia - Instituto de Quimica
b Universidade de Brasilia - Instituto de Química
c Universidade de Brasilia - Instituto de Fisica
d Pontificia Universidade Catolica de SP

The layer-by-layer technique was employed to produce multilayered nanocomposite films that incorporate magnetite nanoparticles (np- MGN, 8.5 nm in diameter) and graphene oxide (GO) layers. The multilayer assembly was performed by alternate dipping of glass slides into a colloidal suspension of np-MGN, that in pH 3 behave as cationic species, and an alkaline suspension of GO, used as source of anions. The multilayer assembly was monitored by UV-vis spectroscopy after every deposited (np-MGN/GO) bilayer and evidenced a stepwise increase on the film´s absorption at 480 nm, up to 10 np-MGN/GO bilayers, which was ascribed to the Fe(II)®Fe(III) electron transfer in magnetite. This trend was only possible own to the electrostatic driven adsorption of components that turns the multilayer assembly self-regulated. Atomic force microscopy revealed that the multilayer morphology was dominated by homogeneous and compact layers of np-MGN, with surface roughness around 13 nm for multilayers with 10 np-MGN/GO bilayers. Treatment with hot aqueous hydrazine resulted in chemical reduction of GO as evidenced by Raman spectroscopy. Nonetheless, the same treatment invariably leaded to disruption of the multilayers. To overcome this drawback, an additional layer of poly(diallyldimethyl ammonium) chloride (PDAC) was introduced in the multilayer assembly. The PDAC layer significantly improved the chemical resistance of the multilayer which could then be reduced by hydrazine without any detectable damage. The electrical properties of the improved multilayer were accessed by impedance spectroscopy, before and after hydrazine treatment. Before the treatment, multilayers were highly insulating and displayed an overall impedance of ~ 105 ohms that remained unaltered over the entire frequency range investigated (20 Hz to 1 MHz). After the treatment, the multilayers´ impedance was significantly decreased to about 60 ohms due to the conversion of GO to RGO (reduced graphene oxide), which is a semiconductor. Moreover, the impedance spectrum of the reduced multilayer displayed a single relaxation process at 10 kHz which was ascribed to the electrical polarization at the np-MGN/RGO interface. The plenty control of morphology and electrical properties as provided by this deposition method turns the np-MGN/GO multilayers potential electrode materials for electrochemical devices such as capacitors and batteries.



298
Bionanocomposites of Graphene-Oxide Reinforced Starch
P Peregrinoa,*, Leonardo Paternob, Maria Jose Salesa, Mauro da Silvac
a Universidade de Brasilia - Instituto de Quimica
b Universidade de Brasilia - Instituto de Química
c Pontificia Universidade Catolica

Bionanocomposites represent today an environmentally friendly strategy for the production of novel materials while employing raw components from the plenty source provided by biomass. These systems are comprised by a continuous biopolymer matrix loaded with nanofillers, usually inorganic in nature. While the biopolymer matrix ensures the material’s biodegradability, nanofillers provide the required thermal, mechanical, and electrical properties, usually very poor in the biopolymer alone. In this regard, we have produced bionanocomposites films by casting an aqueous suspension of acetylated starch mixed with different amounts of graphene oxide (GO). Apart from inherent environmental benign features of starch, GO is a cheaper and more feasible source of graphene, which displays unusual optical, electrical and mechanical properties and should exert in the near future a profound impact in organic electronics and engineering materials. The resulting starch/GO suspension as well as the cast films were rather homogeneous and transparent to visible light at GO loads up to 0.1% wt. Higher GO loads turn films more opaque with transparency bellow 30% and also very brittle. The presence of GO exerted a straightforward effect over the water content in the nanocomposites, which decreased as the amount of GO increased. According to thermogravimetry, the release of water became less endothermic as the GO load increased, with a substantial decrease from 465 J g-1 for plain starch to about 100 J g-1 for the nanocomposite with 0.5% wt of GO. FT-IR spectroscopy provided further evidence for the replacement of water molecules by GO which binds to starch mainly through hydrogen bonds. An additional experiment proved that short time expositions of nanocomposites to UV light (220 nm) could conduct the photochemical reduction of GO structures without any deleterious effect over the starch matrix. Since hydrazine treatment invariably leads to dissolution of starch and disruption of the nanocomposite film, the UV treatment appeared as an alternative approach to prepare starch nanocomposites filled with semiconducting graphene materials.



301
Surface Characterization of Carbon Fiber Treated by Microwave Excited Plasmas
Mauro Oliveira Juniora,*, Choyu Otania, Milton Dinizb, Rita Dutrab, Marcos Massic, et al.
a Instituto Tecnológico de Aeronáutica
b Instituto de Aeronáutica e Espaço
c Universidade Federal de São Paulo

In last decades, the well-known metallic materials have been replaced in many cases by composites reinforced by structural carbon fibers, due to their excellent mechanical properties. The good tensile strength associated with low weight of carbon fibers (CFs) has been an important advantage to overcome heavy duty of quality demands and allow them to be applied in aeronautic and aerospace industries. These high performance carbon fibers are generally obtained in a high temperature carbonization process, usually above 1500ºC, aiming better crystallographic structure organization, which is a temperature dependent characteristic of CFs. Consequently, the tensile modulus and tensile strength rise considerably when the temperature process is increased. However, these carbon fibers have low content of polar groups on their surface, because N, H and O are volatilized during carbonization giving them a surface with poor adhesion characteristics with some matrices used in carbon fiber reinforced composites [1]. This fact leads to the additional surface treatment to elevate their free surface energy. Microwave excited plasmas are presented to be effective in dissociation process of gaseous molecules [2] and some of them are known to be able to treat carbon fibers surface without production of cracks and roughness [3]. In this work, it is presented the effect of exposure of unsized T-300 carbon fibers from Toray to Ar/N2 and Ar/O2 microwave excited plasmas. The surface energy analyses performed by Goniometry showed that few seconds of plasma treatment can be effective to improve significantly the wettability of carbon fiber, and that the energetically enhanced surface condition can be kept for more than one month period after treatment. The exposition of carbon fibers on such plasma environment did not change their crystallinity, in the extent observed by simple XRD analysis. The surface chemistry of treated and untreated carbon fibers was analyzed by FT-IR/ATR/Ge method. This technique has been revealed to be useful to analyze the carbon fiber surface in a depth of tenth of micrometers [4] and for this study showed some interesting spectral changes. The samples treated for 600 seconds showed an increase of some FT-IR spectra bands, generally related to -O binds. Spectra of samples treated in both plasmas for 10 until 120 seconds presented overall decrease of absorption bands intensities when compared to those observed in the samples spectra as received. These reductions denote a cleaning action of plasmas on carbon fiber surface for short period (time) treatments. In this case, the growing wettability of carbon fibers produced by treatment can be justified as the increase of active sites created on the carbon fiber surfaces and/or by incorporation of polar groups in a few atomic layers near the surface, not detected by FT-IR technique. The new surface analyses by means of XPS are being provided to deepen the research about that hypothesis.

[1] CHUNG, D. D. L. Carbon Fiber Composites, Butterworth-Heinemann, 1994.

[2] MOISAN, M. et al. Revue Phys. Appl., v.17, p.707-727, 1982.

[3] OLIVEIRA JR, M. S. et al. Anais do V Congresso Brasileiro de Carbono, Rio de Janeiro/RJ, p.204-208, 2011.

[4] OLIVEIRA JR, M. S. et al. Polímeros (submitted), october, 2012.



305
Microwave synthesis of noble metal (Pt) doped grephene hybrid for efficient visible light photocatalyst
Ullah Kefayat, Zhu Lei, Ghosh Trisha, Park Chong-Yeon, Oh Won-Chun, et al.
Department of Advanced Materials Science & Engineering, Hanseo University

Decorations of grephene with metal complexes are very important for catalysis and their application. In this present work noble metal doped grephene hybrid were prepared by a simple and scalable one pot synthesis method. In which grephene oxide is mixed with Platinium and resulting solution were irradiated by microwave radiation for 300 seconds. In this process simultaneous reduction of grephene oxide into grephene and attachment of noble metal nanocrystals are observed in ethylene glycol solution. The visible light photo catalytic activities of different samples were tested by Rhudamine B and methylene blue is the model contaminant. This analysis gives a promising development towards grephen based efficient photocatalyst that employ visible light as an energy source. Furthermore the Samples were characterized by XRD, SEM, EDX, XPS, Raman spectroscopy, TEM, and UV-vis Spectrometer.



307
Biocarbons for Supercapacitor Electrode Application.
Andrés Cuñaa,*, Nestor Tancredia, Juan Bussia, Violeta Barrancob, José M. Rojob, et al.
a Facultad de Química, DETEMA, Cátedra de Fisicoquímica y Laboratorio de Fisicoquímica de Superficies, Universidad de la República, Uruguay. General Flores 2124, PO Box 11800, CC 1157 Montevideo, Uruguay.
b Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Sor Juana Inés de la Cruz, 3, Cantoblanco, 28049- Madrid, Spain.

Wood residues are ordinary wastes in the forestry industry and their valorization is an important issue. Eucalyptus grandis wood dust was chosen as a model wood residue and Biocarbons (BCs) and activated BCs were prepared from it and studied as active materials for supercapacitor electrodes. Several ordinary activation methods were used and microporous activated BCs with specific surface areas up to 900 m2 g-1, and different content of oxygenated surface groups were obtained. The preparation or activation temperature is the parameter that mainly affects the electrical conductivity. For temperatures above 700 °C, the samples reach an electrical conductivity as high as 1 S cm-1. The specific capacitance of the activated BCs reaches values up to 203 F g-1 in acidic electrolyte. The highest specific capacitance is obtained when chemical activation with ZnCl2 at 900 ºC followed by chemical oxidation with nitric acid is used. BCs activated with ZnCl2 at 900ºC and CO2 at 800ºC displayed good rate capability and the maximum power density. Activation with ZnCl2 at 900ºC also leads to BCs with high energy density up to 50 Wh kg-1 in organic electrolyte. These results show that E.grandis wood dust is a promising low cost and environmental friendly precursor for biocarbon electrodes.



308
Effect of Anti-oxidation Coating on the Characteristics of Carbon/Carbon Composites Prepared by CVI Process for Brake Disk Applications
Donghwan Choa,*, Jinsil Cheona, Chaewook Chob, Jonghyun Parkb
a Department of Polymer Science and Engineering, Kumoh National Institute of Technology, Gumi, Gyeongbuk 730-701, Korea
b DACC Co., Ltd., Jeonju, Jeonbuk 561-844, Korea

Carbon/carbon composites have been widely used in aircraft and automobile brake disk applications and also in extremely high temperature structural material applications such as missile and aerospace and fusion reactors due to their extremely high temperature resistance, high thermal conductivity, low thermal expansion, high wear resistance, and excellent mechanical properties at high temperature. However, they have drawbacks such as poor oxidation resistance particularly above about 400°C in air, resulting in considerable decrease of their mechanical properties. In most cases, carbon/carbon composites are used in thermally oxidative environments. This oxidation behavior limits their high temperature applications and shortens their lifetime in service. Such the oxidation behavior may be protected by appropriate anti-oxidation coating technique. Consequently, in the present study, two different types of antioxidant coating materials, which were developed industrially, were applied to the carbon/carbon composites prepared by chemical vapor infiltration (CVI) process. One of the antioxidants used was phosphorous-based and the other was BN-based. The effect of single- and multi-antioxidant coating of two different types of anti-oxidants on the characteristics was also studied. The oxidation tests of carbon/carbon composites were performed with multiple heat-treatment steps in a furnace of high temperature oxidation environments in air, which were similar to causing the oxidation of aircraft brake disks in practice. The characteristic results are discussed in terms of elemental analysis, surface morphology, thermal stability, thermal expansion, and microstructure. Uncoated carbon/carbon composites were used for comparison.



313
Curing mechanism of multilayer graphene oxide (GO) films by irradiations with visible light.
Mauro da Silvaa,*, Marco Cavallarib, Leonardo Paternoc, Guilherme e Silvab, Ely Diranid, et al.
a Pontifícia Universidade de São Paulo, FCET, São Paulo - SP, Brazil
b Escola Politécnica da Universidade de São Paulo, São Paulo - SP,Brazil
c Universidade de Federal de Brasília,Brasília – DF, Brazil
d Pontifícia Universidade de São Paulo, FCET, São Paulo - SP, Brazil; Escola Politécnica da Universidade de São Paulo - SP,Brazil

The present work shows the proposition of a curing mechanism of multilayer graphene oxide (GO) films caused by irradiations with visible light. The film was assembled in glass slide by a photo-assisted centripetal compression method using an acqueous dispersion of GO. The film was characterized using Raman spectroscopy, transient near infrared optical emission, FTIR/ATR spectroscopy, scanning electron microscopy (SEM) and electrical measurements. Near infrared luminescence spectroscopy of GO dispersion provides strong evidences that in situ visible light irradiation sensitizes the acqueous molecular oxygen (3O2) generating Δ1O2. The as-formed high energy Δ1O2 attacks graphene oxide sheets at the double bonds and aryl groups, forming grafted endoperoxide groups. These as-generated grafted endoperoxide groups by thermal or photochemistry decomposition generate grafted reactive oxygen species that attack the remaining double bonds and aryl groups of neighborhood sheets forming ether bridges, properly curing the film. FTIR/ATR spectra of photoassisted assembled films show the peak assigned to presence of assymetric ether bridges and the intensity of this peak grows with time of irradiation during assembling. Additionally, the FTIR/ATR spectrum of assembled films using a GO solution containing a Δ1O2 scavenger (10 mM of NaN3) does not show evidence of ether peak which strongly supports the proposed mechanism. The Raman analysis of the resulting film shows a typical graphene signature with G and D bands pointing out the turbostatic character of film. SEM images performed on the edge of these films show an uniform thickness of about (75 ± 1) nm. Eletrical measurements of these films were performed on bottom gate bottom contact thin-film transistors built over a silicon wafer. It provides (0.14 ± 0.02) Ω.cm of eletrical resistivity, (18.4 ± 2.6) kΩ/sq of sheet resistance and 200 cm2/V.s charge carrier mobility for both types.



314
Synthesis of Coal-based Graphene and its Photocatalytic Properties for CO2 Conversion
Yating Zhanga, Anning Zhoua, Xiaoqian Zhanga, Yunpeng Sia, Jieshan Qiub,*, et al.
a College of Chemistry and Chemical Engineering, Xi’an University of Science and Technology
b Carbon Research Laboratory, Liaoning Key Lab for Energy Materials and Chemical Engineering, State Key Lab of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology

Graphene has attracted extensive attention and research interests because of its unique properties. Here we report on the synthesis of coal-based graphene (CBG) with anthracite as a raw material by a process combining several steps including catalytic graphitization, chemical oxidation, and dielectric barrier discharge (DBD) plasma treatment. The results show that the catalysts of graphitization have remarkable effects, i.e. to reduce the thermal treatment temperature, to increase the graphitization degree of graphitic carbon and to improve the properties of CBG. The Pt/CBG composites in which CBGs are decorated with highly dispersed Pt nanoparticles on the surface have been fabricated by the H2 DBD plasma-assisted deoxygenation of graphene oxide (GCO) in the solution of chloroplatinic acid under ultrasonic conditions. The Pt/CBG, GCO, CBG, and the conventional TiO2 were tested as photocatalysts for CO2 reduction, of which Pt/CBG shows good catalytic properties than other materials including the conventional TiO2.



315
Measuring electrical conductivity on carbons
Ana Arenillas, Esther G. Calvo, Natalia Rey-Raap, Jose M. Bermúdez, J. Angel Menéndez, et al.
Instituto Nacional del Carbón CISC, Apartado 73, 33080 Oviedo, Spain

A large variety of carbon materials are being increasingly used in different electronic and electrochemical devices. Therefore, among other very valuable properties the electrical conductivity of these carbons is of huge importance in order to evaluate the viability of these materials in these applications. Measuring the electrical conductivity of carbon is not, however, straightforward. Thus, different methods are available and described in the bibliography. The different possibilities can be divided in two main groups: (i) measuring the sheet conductivity based in the four-points method and (ii) measuring the conductivity of the material compacted in a mould at a certain pressure. Each method presents certain strengths and drawbacks, for instance in the four-point method low amount of sample is needed but the sample should agglomerate itself otherwise an additive is needed for the measurement. On the other hand, the compacted test-bars method needs an optimisation of the shape of the mould, amount of sample and pressure used in the test for each material, but no additives are required.

In this work the electrical conductivity of a large variety of carbons, ranging from ordered ones like graphite, graphene, nanotubes or nanofibers to disordered carbons as commercial activated carbons used in electrochemical applications, was measured using the four-points method and the compacted test-bars method. For the former, a current source (Keithley 6221) and a nanovoltmeter (Keithley 2182A) besides a 4-Point-Prober EB-SR-4-6L from Everbeing were used , while for the compacted test-bars method the sample was placed between two copper electrodes in a non-conductive mould and pressed, a current source (Time Electronics 1044) and a multimeter (Fluke 45 Dual display) were used for measurements.

Results are reported and compared and discrepancies discussed. The ASTM standards tests were also taken into account in the discussion. Bearing in mind the advantages and disadvantages of each method and the results obtained for each type of carbon, a recommendation of the most suitable method is proposed.



317
INFLUENCE OF CARBONIZATION ON MICROSTRUCTURE AND TENSILE STRENGTH OF T300 PAN-BASED CARBON FIBERS
Gengheng Zhou, Joon-Hyung Byun, Sang-Bok Lee, Jin-Woo Yi, Wonoh Lee, et al.
Korea Institute of Materials Science

Carbon fibers are widely used as reinforcements in composites due to their high specific strength and modulus which can be remained even at high temperature up to 2000oC. To study the influence of high-temperature treatment on the tensile properties of high strength PAN-based carbon fibers, two types of commercial high tensile strength PAN-based carbon fibers, T300 and T700 carbon fibers were heat-treated at 1400oC, 1600oC, 1800oC, 2000oC and 2300oC under inert atmosphere. The tensile properties of these fibers plus as received ones have been investigated by a single fiber tensile test with a gauge length of 20mm. The statistical distributions of the tensile strength were characterized and the influence of high-temperature treatment (HTT) on the tensile properties was discussed. The average tensile strength of T300 carbon fibers fluctuated with HTT temperature. It increased from 3.43 GPa to 3.58 GPa after HTT at 1400oC. Then it decreased dramatically to 2.25 GPa after HTT at 1600oC and gradually increased to 2.68 GPa after HTT at 1800oC. With the increasing of HTT temperature, it increased significantly to 3.54 GPa after HTT at 2000oC. Finally, it decreased to 2.96 GPa after HTT at 2300oC. Surprisingly, T700 carbon fibers show quite a difference phenomenon. The average tensile strength decreased dramatically from 5.46 GPa to 1.97 GPa after HTT at 1600oC. After a little increasing after HTT at 1800oC, from 1.97 GPa to 3.17GPa, the average tensile strength decreased continuously to 2.09 GPa after HTT at 2300oC. The values of Weibull modulus for all the fibers have been calculated based on the distributions of the tensile strengths. The Weibull modulus for the as received T300 and T700 carbon fibers are 6.55 and 4.62, respectively. The Weibull modulus for T300 carbon fibers after HTT at 1400oC, 1600oC, 1800oC, 2000oC and 2300oC were 11.02, 3.12, 4.51, 6.44 and 2.40, respectively. The corresponding Weibull modulus for T700 carbon fibers after HTT at 1400oC, 1600oC, 1800oC, 2000oC and 2300oC were 3.74, 3.54, 6.27, 3.45 and 3.17, respectively. Based on the observations, T300 carbon fibers were recommended to be used as reinforcements in the composites under high temperature applications up to 2000oC, while T700 carbon fibers should be used in the composites under low temperature applications.



318
Phenol photocatalytic degradation by TiO2/Cu-doped carbon composites
Marta Andradea,*, Ana S. Mestrea, Juan Matosb, Ana P. Carvalhoa, Conchi O. Aniac
a Dpt. Química e Bioquímica and CQB, Faculdade de Ciências da Universidade de Lisboa, Ed. C8, Campo Grande, 1749-016 Lisboa, Portugal
b Dpt. Catalysis and Alternative Energies. Venezuelan Institute for Scientific Research (IVIC), 20632, Caracas 1020-A, Venezuela
c Instituto Nacional del Carbón (INCAR, CSIC) 33011, Oviedo, Spain

Heterogeneous photocatalysis is an expanding technology for the removal of toxic pollutants in wastewater treatment plants. Carbons have been successfully used as supports of photoactive species and carbon/semiconductor composites have shown quite high efficiencies for the photodegradation of a variety of pollutants [1,2]. Recently, it has also been reported that certain activated carbons possess a significant level of self-photochemical activity [3]. On the other hand, the incorporation of transition metals with catalytic activity on the surface of activated carbons is a powerful synthesis tool which offers great possibilities in the preparation of selective adsorbents and/or catalysts for processes of environmental remediation, in particular in the adsorption and/or degradation of contaminants. In this context, the aim of the present work was to investigate the photocatalytic activity of composites of TiO2/Cu-doped carbons on the degradation of phenol from aqueous medium.

Carbons with diferent copper loadings were prepared by a one-pot route consisting in the impregnation of a lignocellulosic industrial residue (carbon precursor) using copper nitrate and K2CO3, followed by chemical activation to develop a porous network. The obtained materials were characterized by several techniques (gas adsorption, TEM, XPS, XRD) and resulted to be essentially microporous materials exhibiting a homogenous distribution of copper species within the carbon matrix. The photocatalytic activity of the hybrid carbon/TiO2 composites towards phenol degradation was found to be strongly modified by the incorporation of copper in the carbon material. The copper-loaded hybrid composite increased the photodegration rate of phenol in solution, as well as the mineralization rate of the intermediates, revealing a copper-promoted enhancement of the carbon/titania synergy effect [4]. These results have been analyzed in terms of the chemical state of the copper species incorporated to the carbon matrix.

[1] R. Leary, A. Westwood, Carbonaceous nanomaterials for the enhancement of TiO2 photocatalysis, Carbon 49 (3) 2011, p. 741-72.

[2] J. L., Faria, W. Wang, Carbon materials in photocatalysis (chapter 13), in Carbon Materials for Catalysis, (Serp, Ph., Figueiredo, J. L. eds.) Wiley & Sons, 2009.

[3] L.F. Velasco, J.B. Parra, C.O. Ania, Role of activated carbon features on the photocatalytic degradation of phenol, Appl. Surf. Sci. 256 (17) 2010, p. 5254-8.

[4] J. Matos, E. García-López, L. Palmisano, A. García, G. Marcì, Influence of activated carbon in TiO2 and ZnO mediated photo-assisted degradation of 2-propanol in gas-solid regime, Appl. Catal. B: Environ. (99) 2010, p. 170-180.



319
IMPROVEMENT OF PROPERTIES OF TRANSPARENT ELECTRODES VIA CNT SELF-ASSEMBLY
Laurent MAILLAUD, Alain PENICAUD, Cécile ZAKRI, Philippe POULIN
Centre de recherche Paul Pascal - PESSAC - FRANCE
The realization of transparent and conductive electrodes is a major challenge for the development of new screens, keyboard, photovoltaic panels or light emitting diodes. Current technologies rely on the use of costly inorganic oxides with a limited availability. In addition these materials are brittle and cannot be used on flexible electrodes. Carbon nanotubes (CNTs) are among the most promising candidates as an alternative to inorganic oxides [1]. They have a high aspect ratio (length / diameter) and a very good electrical conductivity. Therefore they can form conductive networks at low concentrations. This ensures electrical conductivity while maintaining good optical transmission. However, achieving performances adapted to the needs of applications requires a fine control of the structure of nanotubes networks on the substrate and an understanding of the interactions that lead to this structuring. In this study, we develop conductive inks by dispersing CNTs in aqueous solutions in the presence of surfactants and / or polymers and exposure to ultrasound. The obtained dispersions are deposited as thin layers over a flexible substrate (PET sheet) using a filtration membrane method. The key objective is the achievement of the best compromise between conductivity and transmittance. Such an objective is approached via the control of the interactions between the particles. Interactions affect the rheological, wetting and self-assembly properties of the CNTs. In particular, it is theoretically expected that weak attractive forces should promote local alignment of the CNTs along with a decrease of the percolation threshold [2]. This phenomenon could lead to improvements of electrical conductivity [3]. Indeed, local alignment should lead to better electrical contacts and the lower percolation threshold should allow a decrease in the concentration of CNTs responsible of the drop in transmittance. We validate in this work these theoretical expectations by showing that increasing the surfactant concentration in the dispersion actually promotes contacts and local alignment of CNTs because of weak depletion forces induced by the micelles. The morphology in the solution is investigated by cryo-TEM analyses. The influence of attractive interactions has been studied in the case of the formation of thin dried films. The control of the network morphology leads to improvements of the performance of conductive transparent electrodes based on carbon nanotubes. It is also shown that weak attractive interactions result in an increase of the solution viscosity which yields improvements of processability. References [1] K. A. Sierros, D. S. Hecht, D. A. Banerjee, N. J. Morris, L. Hu, G. C. Irvin, R. S. Lee, D. R. Cairns, Thin Solid Films, 518 (2010), pp. 6977–6983. [2] A. V. Kyrylyuk and P. van der Schoot, PNAN, 105 (2008), pp. 8221-8226. [3] B.Vigolo, C. Coulon, M. Maugey, C. Zakri, P. Poulin, Science, 309 (2005), pp. 920-923.


320
Tannin as a key precursor of new porous carbon materials
Gisele AMARAL-LABATa,*, Andrzej SZCZUREKa, Vanessa FIERROa, Antonio PIZZIb, Alain CELZARDa
a Institut Jean Lamour, UMR Lorraine University - CNRS 7198, ENSTIB, Epinal (France)
b LERMAB - Lorraine University, Epinal (France)

Flavonoid tannins are natural oligomers extracted from vegetable resources, especially from tree barks, by an ecological process only based on hot water. Their polyphenolic nature explains both their reactivity for preparing high-quality thermoset resins and the high carbon yield of such resins after pyrolysis. These advantages, combined to their low cost, renewable and non-toxic character, definitely make tannin an essential precursor of new materials able to compete with phenolic resins and derived carbon materials, such as those based on expensive, synthetic, resorcinol.

In this presentation, our most recent results will be presented, unambiguously demonstrating the interest of tannin for preparing valuable porous carbons such as gels, foams, and porous monoliths. These materials just prepared in our lab will be introduced and their most remarkable properties will be described.

First, tannin allowed the preparation of the broadest family of hydrogels in terms of porous texture, from which very different carbon aerogels, cryogels or xerogels could be prepared. Versatile characteristics could be obtained through the drawing of the first phase diagram of tannin in water, alone or in presence of another natural polyphenolic molecule, lignin. The structure of carbon aerogels was strictly controlled through the first, systematic, study of the (strong) impact of the parameters of the supercritical drying process. Carbon cryogels were found to have the same electrochemical behaviour as their synthetic counterparts. Unique carbon xerogels could also be obtained, based on soft-templating of tannin, having single-sized mesopores centred on 10 nm.

Second, tannin-based resins could be foamed and formed homogeneous and flawless cellular vitreous carbon foams. Our last studies revealed that the acoustic properties of such foams were rather poor, due to their high air flow resistivity. However, we have shown that tannin-based carbon foams were very appropriate materials to apply the double porosity concept, by which the sound absorption coefficient could be successfully increased to 100% in some targeted frequency ranges. We have also shown that carbon foams are very interesting materials for electromagnetic shielding, as they are almost not transparent to microwaves, highly conducting and at the same time, ultra-lightweight. Additionally, tannin-based carbon foams were excellent precursors of microcellular SiC foams, characterized by extremely thin pore walls, a feature hardly obtained by conventional precursors and techniques.

Finally, we will report the first carbon monoliths based on polymerized High Internal Phase Emulsions (polyHIPEs) derived from tannins. Such new porous materials were produced by emulsifying a tannin solution with oil, hardening the whole and extracting the oil. The resultant carbons had a fully open and interconnected porosity, whose characteristics were easily modified by suitable changes of emulsion formulation. New carbon foams derived by a process without oil were also obtained, whose average cell sizes were tuned by the simple change of tannin concentration in water.



321
Improving the sound absorption ability of vitreous carbon foams
Gisele AMARAL-LABATa, Emmanuel GOURDONb, Vanessa FIERROa, Antonio PIZZIc, Alain CELZARDa,*
a Institut Jean Lamour, UMR Lorraine University - CNRS 7198, ENSTIB, Epinal (France)
b LGCB LTDS CNRS 5513, ENTPE - Lyon University, Vaulx en Velin (France)
c LERMAB - Lorraine University, Epinal (France)

Acoustic performances of vitreous carbon foams were investigated for the first time in terms of frequency-dependent sound absorption coefficient. Two kinds of foams were considered: cellular vitreous carbon (CVC) and reticulated vitreous carbon (RVC) foams. Whereas the former clearly presented spherical cells connected with each other through smaller circular windows, the latter were just made of struts having a triangular cross-section connected with each other at well identified nodes. CVC foams were prepared from a tannin-based resin which was foamed by a blowing agent, hardened and pyrolysed, and were investigated in an impedance tube, which is the usual tool for determining acoustic parameters. Sound absorption coefficients of RVC foams, supplied by ERG Materials and Aerospace Corporation (Oakland, CA), were recalculated from the very few data existing in the literature. Both kinds of foams were available in different porosities and different linear cell densities expressed in pores per inch (ppi).

We show that sound absorption coefficients are strongly related to both porosity and air flow resistivity of the materials. A compromise is indeed required. Air must penetrate the material, so if the resistivity is too high, the acoustic wave can’t penetrate and the material is reflecting. Therefore, a higher resistivity leads to a lower absorption, as observed for tannin-based CVC foams in the present work. Conversely, if the resistivity is low, air easily enters the material but the air flow resistance might be too low for attenuating the acoustic wave. Therefore, a higher resistivity leads to a higher absorption, as observed for RVC foams. As a conclusion, at similar porosity and number of ppi, RVC foams are much better than CVC foams for absorbing sound.

However, the high air flow resistivity of CVC foams can be significantly decreased and adjusted by means of perforations of suitable diameters, resulting in a high permeability contrast which is necessary for achieving a significant increase of sound absorption coefficient. Perforating CVC foams indeed led to 100% of sound absorption in a targeted frequency range. It is expected that any other cellular vitreous carbon foam behave similarly and can thus compete with other excellent sound absorbing materials.



322
Turning adhesive formulations into valuable carbon gels
Gisele AMARAL-LABATa,*, Andrzej SZCZUREKa, Vanessa FIERROa, Antonio PIZZIb, Alain CELZARDa
a Institut Jean Lamour, UMR Lorraine University - CNRS 7198, ENSTIB, Epinal (France)
b LERMAB - Lorraine University, Epinal (France)

In the recent years, interest has grown for new ways of preparing carbon aerogels that might be cheaper than the traditional gels derived from resorcinol–formaldehyde resin subsequently dried in supercritical CO2. Resorcinol is indeed a very expensive chemical, and high amounts of liquid CO2 are required for solvent exchange of gels and solvent extraction in the supercritical state. Therefore, various cheap precursors have been suggested, as well as new, inexpensive, drying methods. Among these, chemicals like phenol, melamine, mixed phenol–melamine systems, polyvinyl chloride, isocyanate polymers, cresol and cellulose have been successfully tested.

We show here that formulations habitually used for preparing adhesives may be changed and adapted to the preparation of highly porous materials. A cold-setting adhesive indeed experiences a gel point above which a hard material is formed, having the lowest porosity as possible. However, the formulation can be modified and diluted in order to obtain a material having high pore volumes. With this aim in view, we have successfully used different adhesive formulations such as tannin-formaldehyde, tannin-resorcinol-formaldehyde, phenol-formaldehyde and branched phenol-resorcinol-formaldehyde for preparing various kinds of gels. The latter were then converted into aerogels or cryogels, whether they were supercritically or freeze-dried, respectively, and finally pyrolysed to get carbon gels.

This presentation will demonstrate how broad can be the range of carbon gels’ porous textures which can be obtained, depending on composition, dilution, pH of the resin and dying mode. We will also show that cheap adhesive formulations can be used for preparing carbon gels having similar characteristics as those derived from expensive resorcinol-formaldehyde resins.



324
COAL-BASED AROMATIC RESINS: DEVELOPMENT AND UTILIZATION
Xiaoyi Gong, Ying Sheng, Shengzhen Zhang, Junqing Liu, Dongfang Zheng, et al.
National Institute of Clean-and-Low-Carbon Energy

Aromatic resins consist of asphalt, isotropic pitch and mesophase pitch. Asphalt represents one of the most important components of paving and roofing materials. Isotropic and mesophase pitches are the precursors of carbon materials and graphite electrodes. The annual world consumption of aromatic resins is estimated of 50 million tons. Most of the aromatic resins come from heavy cuts of petroleum refining, only a small portion is from coal. As coal refining technology advances at a fast pace in recent years especially in China, coal-based aromatic resins have received more attention than ever before from engineering and materials science community. Coal-based aromatic resins have the following properties that are superior over petroleum-based aromatic resins: stronger binding strength, higher aromatic content, and higher carbon yield. Depending on the polymerization conditions, coal-based aromatics show better controllability and generate highly oriented mesophase structures that provide the graphite fibers with high modulus and thermal conductivity. Graphite fibers with over 900 GPa Young’s modulus were produced with coal tar pitch in the lab of China Coal Research Institute.

To further develop and utilize coal-based aromatic resins, three issues were identified to be addressed: high ash content, high concentration of nitrogen- and sulfur-containing hydrocarbons, and poor understanding of the polymerization process. Separation technologies including acid wash, solvent extraction, and centrifuge were investigated and compared regarding ash removal and heteroatom-containing hydrocarbon removal. Thermal condensation to convert the oligomers into isotropic pitch and mesophase pitch was investigated and compared to catalytic condensation regarding the product properties – mesophase content and morphology, softening point, melt viscosity, carbon to hydrogen atomic ratio, and volatile concentration. Understanding of the polymerization mechanisms requires quantitative analysis and characterization on the molecular level for oligomers, intermediate and final pitch products. It also requires modeling for process parameters’ effects on properties of final products. Both analysis and modeling face challenges due to the complex composition and pseudo solubility of coal-based aromatic resins. A strategic approach needs to be constructed to tackle these challenges in order to make the most of coal-based aromatic resins and to fully develop their potential applications.



325
Preparation and capacitive performance of the anion intercalation graphite materials as positive electrode materials
hao zhang, bin xu, wenfeng zhang
research institute of chemical defense

Carbon materials are often used as anode materials of Li-ion batteries because they have good charge and discharge reversibility, large capacity and low discharge platform. Now carbon materials becoming research focus because of their reversible insertion and de-intercalate of anions. Here, we prepared the needle coke at 1500℃ and 2800℃. Then, the influence of the degree of graphitization to the performance of graphite was researched. The specific discharge capacity of needle coke sintered at 1500℃ and 2800℃ are 70.1 mAh/g and 90.6 mAh/g in organic electrolyte when the current density was controlled at 50 mA/g. The value capacity is 55 mAh/g when the current density was raised to 5 A/g. However, the specific capacity of commercialization active carbon is only 35.9 mAh/g when the current density was controlled at 50 mA/g. The retention of the capacitance after 1000 charge-discharge cycles are 89.2% and 95.7%, respectively when the current density was controlled at 1A/g.



326
Determination of crystallite size in polished graphitized sp2 nanostructured carbon by Raman spectroscopy
Mohamed Ramzi AMMARa,*, Olga MASLOVAa, guillaume GUIMBRETIEREa, AURELIEN CANIZARESa, Jean-Noel ROUZAUDb, et al.
a CEMHTI
b ENS

Raman spectrum of the graphitic matter is known to give detailed information about its structural features making Raman spectroscopy a widely used tool in the last four decades. It has historically played an important role for the characterization of pyrolitic graphite, carbon fibers, glassy carbon, pitch-based graphitic foams, nanographite ribbons, carbon nanotubes, fullerenes, and graphene. For instance, a perfect crystalline sp2 carbon is characterized by a single sharp band centered at 1580 cm1 (the so-called G band) in the first-order Raman spectrum. It is the doubly degenerate phonon mode (E2g symmetry) at the Brillouin zone center that is Raman active for sp2 carbon networks. However, the introduction of disorder within the structure (doping, edges, defects….) breaks the crystal symmetry and activates certain vibrational modes that would be silent otherwise. These bands of the first-order Raman are called defect bands (D~1200–1400 cm1) and (D~1600–1630 cm1). They are known to be dispersive in frequency due to the double resonance process. Varying efforts have been devoted to determine the carbon “crystallite” diameter La based on the ratio between the intensities of the disorder-induced D band and the first-order graphite G band (ID/IG). After the pioneering work of Tuinstra and Koenig who performed systematic Raman and x-ray diffraction characterizations showing the proportional relationship between ID/IG (using fixed excitation laser energy) and the inverse of La determined from various disordered graphitic materials, Knight and White derived an empirical expression to measure the “crystallite” diameter La from the ID/IG. This obtained relation can only be applied to large sp2 graphitized carbon crystallites, whereas another relationship was proposed by Ferrari and Robertson for highly disordered carbon. Later, a general equation was developed for nanographites (La>20 nm) by using any excitation laser energy in the visible range. Great interest is to be attributed to all these correlations. However, this parameter fails in the case of polished graphitized carbon (i.e., unpredictable increase of ID/IG leading to the overestimation of the intrinsic structural disorder). It is important to underline that the polishing process is usually required for some carbon materials and that the polishing-induced Raman spectra change has been known for many years. Consequently, an alternative for this parameter is needed in the case of polished samples. The characterization of sp2-nanostructured carbon “nanographites” with various excitation laser energies, pyrolysis temperatures, and varying kinds of precursors will be detailed in this conference, and how to determine the “crystallite” diameter from Raman spectra strongly modified by the effect of previous polishing of the sample.



327
GROWTH OF CARBON NANOMATERIALS IN CARBON-CERAMIC PARTICULATE COMPOSITES
LALIT MANOCHA, GUDDU PRASAD, SATISHA MANOCHA
Department of Materials Science & Centre for Carbon studies, Sardar Patel University, Vallabh Vidyanagar - 388120, Gujarat, India

Carbon nanomaterials offer a wide range of useful properties making them very interesting materials to a broad range of industrial applications. Virgin carbon materials in nanoforms are synthesized basically using laboratory techniques i.e. arc-discharge method, laser ablation method and catalytic chemical vapor deposition. These are used as such for applications in electronic, spectroscopic or medical applications etc or in combination with other materials in the form of composites for structural applications. In the present investigation carbon nanostructures were found to be grown insitu during carbonization of carbon-ceramic composites. Carbon-ceramic particulate composites with fly ash, B4C as reinforcements were developed by powder metallurgical route. These were carbonized to 1000oC in inert atmosphere. Pyrolysis behavior of these materials has been studied. Confirmation of nanostructures in the composites was studied using SEM and TEM. These carbon nanomaterials were found to be growing in random fashion. At various stages coiled type nanofibers were observed. Crystallinity of carbon nanomaterials was studied by XRD. The ID/ IG ratio as calculated from the Raman spectra for the carbon nanomaterials grown were found to be 0.51. Coefficient of friction were studied and were found to be lower as compared with other carbon-ceramic composites made with carbon fiber/oxipan fiber.

Key words: - Solid Carbon, Nanomaterial, SEM, TEM, XRD, Raman, Friction



328
PREPARATION OF THERMAL EXFOLIATED GRAPHENE AND STUDIES ON EFFECT OF GRAPHENE ON THERMAL STABILITY OF GRAPHENE-EPOXY NANOCOMPOSITES
LALIT MANOCHA, HASMUKH GAJERA, SATISH MANOCHA
Department of Materials Science & Centre for Carbon Studies, Sardar Patel University, Vallabh Vidyanagar - 388120, Gujarat, INDIA

Graphite oxide was synthesized by modified Hummers method using natural graphite flakes as starting material and then graphene was prepared through thermal exfoliation treatment of dried graphite oxide paper. This thermal exfoliated graphene (TEG) was characterized using SEM, TEM, Raman and XRD techniques. Nano composites were fabricated with TEG and Epoxy by using solution mixing method. The influence of graphene on the thermal stability and glass transition temperature of nano composites was investigated by using thermo gravimetric analysis and differential scanning calorimetry respectively. The thermo gravimetric results showed higher thermal stability of composites in comparison with pure epoxy and also increase char concentration with increase in graphene content. It shows that pure epoxy resin thermally degrades at 346oC temperature and composites show thermal degradation at higher temperature at 350oC for 0.05 wt%. Remaining oxygen functionalities on graphene acted as catalysts for cross linking of epoxies which increased decomposition temperature of resulting composites. DSC results showed increase in glass transition temperature from 68.63oC for pure epoxy to 78.15oC for 0.05 wt% graphene loaded nano composites.

Key words: graphene, thermal exfoliation, thermal stability, nano composites



329
Preparation and lithium storage performance of hierarchical porous carbons by dual template approach
Song Ranran, Song Huaihe, Chen Xiaohong
State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing, 100029, PR China

Novel hierarchical porous carbon (HPC) with micropores, mesopores and macropores were prepared on a large-scale by using thermoplastic phenolic formaldehyde resin as the carbon source and copper nitrate and silicon oxide nanoparticals as the template precursors. HPC exhibited high specific capacity and favorable high-rate performance when used as anode material for lithium ion batteries (LIBs). The reversible capacities were 918 mAh g-1 at a current density of 50 mA g-1 and 256 mAh g-1 even at 1 A g-1. In this paper, the effect of additive amount of silicon oxide nanoparticals on the morphology, specific surface area, porous structure and lithium storage performance of HPC were investigated by SEM, TEM, BET and electrochemical measurements.



330
High performance asymmetric capacitor based on zeolite-templated carbon and KOH-activated carbon
Khanin Nueangnoraja,*, Hirotomo Nishiharaa, Takashi Kyotania, Ramiro Ruiz-Rosasb, Emilia Morallónc, et al.
a Institute of multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 Japan
b Departamento de Química Inorgánica e Instituto Universitario de Materiales, Universidad de Alicante. Carretera de San Vicente del Raspeig S/N, 03690 San Vicente del Raspeig (Alicante), España
c Departamento de Química Física e Instituto Universitario de Materiales, Universidad de Alicante. Carretera de San Vicente del Raspeig S/N, 03690 San Vicente del Raspeig (Alicante), España

Asymmetric capacitor was constructed by using zeolite-templated carbon (ZTC) as a positive electrode and KOH-activated Spanish anthracite as a negative electrode. ZTC possesses a very high specific surface area and ordered pore structure replicated from the zeolite template. Molecular model of ZTC reveals that it contains a lot of edge sites, which results in its high surface area. Moreover, it has been recently reported that ZTC can be electrochemically oxidized by an anodic polarization, which gives rise to the pseudocapacitance in the positive potential region. Therefore, ZTC was selected as a positive electrode in this study. On the other hand, the material for a negative electrode should be stable upon the cathodic polarization and the KOH-activated Spanish anthracite meets this requirement. It was thus selected as the negative electrode.

To construct the asymmetric capacitor, we optimized the mass of each electrode based on the equation developed by Snook et al., considering the capacitance of each material in a three-electrode system; each carbon electrode was first characterized in the three-electrode cell and the capacitance was calculated from the charge/discharge measurement (1 M H2SO4, 25 mA/g). A two-electrode capacitor was then assembled by using the optimized mass ratio, which is calculated from the obtained capacitances of each electrode. Its electrochemical performance was characterized by means of cyclic voltammogram (5 mV/s) and galvanostatic charge/discharge (25 mA/g) measurements in 1 M H2SO4 within the potential window of 1.4 V. In addition, the potential of ZTC electrode was followed by another auxiliary Ag/AgCl (in sat. KCl) reference. Moreover, the cyclability of this capacitor was tested with 5000 cycles of charge/discharge (500 mA/g) measurement. It has been found that this asymmetric capacitor possesses a high capacitance (ca. 90 F/g, based on the total weight of carbon material in the electrodes) with an excellent cyclability. It retains 83 % of initial capacitance after 5000 cycles of duration test.



333
TEM study of perpendicular/parallel orientation of aromatic layers in self-supported ultrathin carbon films from BBL polymer
Noriko Yoshizawa, Yasushi Soneda, Masaya Kodama
National Institute of Advanced Industrial Science and Technology

Poly(benzisimidazobenzophenanthroline) (BBL) is one of the rigid-rod polymers with large molecular plane of ladder-like structure. It was revealed in our previous study that the BBL polymer films prepared by a casting method showed remarkable carbonization yield (80% at 1,000 °C, 65% at 2,500 °C), and that their carbonized films had high crystallinity comparable to polyimide-derived carbon films in respect to their crystallite size and degree of orientation. Furthermore, we prepared self-supported ultrathin (10-102 nm order in thickness) carbon films by a heat-treatment of spin-coated BBL films up to 2800 °C. In preparation of these carbon films, it was found that a shrinkage behavior during the heat-treatment as well as mechanical properties of them were dependent upon the type of acid (MSA or TFMSA) for dissolving BBL polymer in the spin-coating process. In order to relate these characteristics of the ultrathin carbon films to their nanostructure, TEM observation was done at an accelerating voltage of 120 kV. The samples for the TEM study were prepared by tearing the film with tweezers for a top-view observation (surface view, electron beam was normal to the film surface), or by an ion-milling method for a side-view observation (cross-sectional view, electron beam was parallel to the film surface). According to these TEM investigations with electron diffraction patterns, bright- and dark-field images and carbon 002 lattice images, it was clarified that; (1) the ultrathin carbon film prepared from the MSA solution of BBL polymer showed microtexture in which aromatic carbon layers were preferentially oriented perpendicular to the surface of the film, and (2) those from the TFMSA solution consisted of stacking structure of aromatic layers well developed along the surface of the film. Formation of these unique structure in the BBL-derived ultrathin carbon films will be also discussed in the presentation with the structure of polymer films as well as their morphological changes during the heat-treatment.



334
Porous carbon from aqua mesophase pitch for supercapacitors
Wenfeng Zhanga,*, Hao Zhanga, Bin Xua, Zheng-Hong Huangb, Feiyu Kangb, et al.
a Research Institute of Chemical Defense, China
b Laboratory of Advanced Materials, Department of Materials Science and Engineering, Tsinghua University, China

Porous carbon was prepared from aqua mesophase pitch (AMP) by the combination of nano-sized MgO template method and NaOH activation process. The AMP was a product of oxidation of coal tar pitch with mixtures of concentrated sulfuric acid and nitric acid. Needle-like nano-sized Mg(OH)2 was used as precursor of MgO. The pore structure of the samples was characterized by nitrogen adsorption at 77 K, and the electrochemical performances for supercapacitor were evaluated in a 6 M KOH aqueous solution. The results showed that the prepared porous carbon possesses high surface area, large pore volume and a hierarchical pores structure with abundant micropores and mesopores of 7-15 nm. Rich nitrogen was detected in the porous carbon. At a current density of 0.1 A·g-1, the porous carbon showed a high capacitance of 282 F·g-1, which exceeded 20 μF·cm-2 when normalized by the surface areas. The porous carbon also showed an excellent rate property. 65% capacitance can be retained even at a high current density of 50 A·g-1.



337
Synthesis of sponge-like multi-walled carbon nanotube/chitosan-based carbon composites for oil absorption
Zheng Ling, Nan Xiao, Mengdi Zhang, Ying Zhou, Jieshan Qiu
Carbon Research Laboratory, Liaoning Key Lab for Energy Materials and Chemical Engineering, State Key Lab of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, China

Sponge-like multi-walled carbon nanotube (MWCNT)/chitosan-based carbon composites have been synthesized by a simple yet effective method, in which chitosan-based carbon functions as glue to bond MWCNTs. MWCNTs were dispersed into the chitosan and diluted acetic acid solution under sonication, yielding dispersions that were frozen in a refrigerator for 4 h, followed by a freeze drying process, which finally results in monolithic MWCNT/chitosan composites. After carbonization at 800 °C for 1 h in flowing nitrogen, the sponge-like monolithic MWCNT/chitosan-based carbon composites were obtained. The structure, the bulk density and the oil adsorption capacity of the as-made MWCNT/chitosan-based composites can be easily tuned by varying the concentration of chitosan in the acetic acid solution, and the weight ratio of MWCNTs to chitosan. One of the sponge-like MWCNT/chitosan-based carbon composites shows an adsorption capacity for vegetable oil as large as 100.5 g/g, demonstrating its potential as adsorbent in cleaning and recovery of spilled oils.



338
CHAR MORPHOLOGY FROM COAL BLENDS USING IMAGES ANALYSIS
Deisy Chavesa,*, Edward Garcíab, Maria Trujilloa, Juan Barrazab
a Escuela de Ingeniería de Sistemas y Computación, Facultad de Ingeniería, Universidad del Valle
b Escuela de Ingeniería Química, Facultad de Ingeniería, Universidad del Valle

Char is produced by devolatising coal and represents the dominant stage in a combustion process. It can be used as natural catalysts in the dehydrogenation process of natural gas and corresponds to the first state in the process of producing activated coal. It is well known that chars with morphology of thin-walled, high porosity and large superficial area are more reactive than chars with morphology of thick-walled, low porosity and small superficial area. In this research, char morphology is analysed using coal from three Colombian regions (Antioquia, Cundinamarca, and Valle del Cauca) and their blends. Char are produced in a drop tube furnace using two temperatures (800°C and 1000°C), and one residence time (200ms). A set of 120 char images are acquired using a metallographic microscope coupled with a camera in order to obtain approximately 400 individual particles from each devolatilisation condition. Each char particle is characterised using an images processing software based on morphology features, such as: undevolatilised material, porosity, sphericity and wall thickness. Those morphology features are selected according to the classification proposed by the Combustion Working Group in Commission III of the International Committee for Coal and Organic Petrology (ICCP) and features observed in Colombian chars. Preliminary results have shown that chars with thick-walled, high porosity, and network or spherical shape are dominant in similar rates in pure and blend coals. Moreover, there is not an additive effect in char morphologies from coal blends. However, the use of blend coals at low desvolatisation temperature (800°C) has a beneficial effect in coal combustion, reducing undevolatilised particles and increasing the production of reactive char morphologies.



339
LIQUID PHASE EXFOLIATED MULTI-LAYER GRAPHENE
Andrei Alaferdov, Mara Canesqui, Stanislav Moshkalev
Center for Semiconductor Components, State University of Campinas, Campinas, Sao Paulo 13083-870, Brazil

Fabrication of multi-layer graphene (MLG) with large lateral dimensions and high quality is currently a subject of intense research [1]. In this work we used a liquid phase exfoliation of natural graphite that is a low-cost alternative and allows obtaining solutions with high quality graphene flakes [2].

Graphene dispersions were prepared from natural graphite flakes of mm size in dimethylformamide (DMF) or isopropyl alcohol (IPA) using ultrasound processing (sonication) followed by centrifugation. In order to characterize the process of natural graphite dispersion into graphene sheets, we deposited the obtained solutions onto standard holey carbon mesh grids by drop casting. SEM analysis was performed for a large number of flakes (>102 for each sample) and the statistic for the particle lateral sizes was found to follow log-normal distribution (i.e., the Gaussian distribution for logarithm of the flake sizes), reflecting the specific way of gradual delamination of graphite flakes in a sonication process [3].

The effects of time of sonication and centrifugation, type and temperature of solvent on the size distribution of the graphene sheets were analyzed. During first 2´ of sonication, graphene sheets with lateral size up to 10 µm are mostly formed. The mean size decreases down to ~1 µm for 240´. For study of centrifugation time effect, 2´ and 240´ sonication times were used. Centrifugation time was 15´ and 90´, at speed of 800 rpm. For 2´ sonication and 15´ centrifugation, the fraction of large size flakes reduced slightly. In contrast, when both sonication and centrifugation times are increased (240´ and 90´), the distribution function localizes at small sizes with the mean value of ~ 1 µm. The aspect ratio (lateral size/thickness) was estimated to vary within a range of 50-300 in all cases. From comparison of images and statistics results, it can be concluded that the delamination of graphite occurs quite similarly for both DMF and IPA solvents. It was also determined that for room temperatures, the distribution is more uniform with higher mean size, while for elevated temperatures (40оС) the curve is localized at ~0.9 µm. This change likely occurs due to increased frequency of cavitation events and thus formation of smaller and more numerous graphene flakes at higher temperature as exfoliation of graphite by sonication is believed to be due to shock waves and micro-jets generated in the sonicated liquid [4].

Raman analysis was performed to confirm high quality of graphene, with narrow full width at half maximum values, usually near 16-18 cm-1. The D/G band ratio that is widely used to evaluate the quality graphene flakes, was found to vary from near 0 to 0.2, a result which is consistent with small defect-free flakes.

References

  1. Y. Kopelevich , P. Esquinazi , Adv. Mater. 19, 4559 (2007).
  2. Y. Hernandez, V. Nicolosi, M. Lotya, F.M. Blighe at al. Nat. Nanotechnology. 3, 563 (2008).
  3. A.N. Kolmogorov. The proceedings of the USSR Academy of Sciences. 31, 99 (1941).
  4. G. Cravotto, P. Cintas. Chem. Eur. J. 16, 5246 (2010).


340
Anisotropy of oxidation rates along and across basal plane in suspended multi-layer graphene.
Victor Ermakov, Andrei Alaferdov, Alfredo Vaz, Stanislav Moshkalev
Center for Semiconductor Components, State University of Campinas, Campinas, Sao Paulo 13083-870, Brazil

Thermal properties of graphene in its various forms like single layer and multi-layer graphene (SLG and MLG, respectively) are currently subject of intense research activities. Here, results of a study of multi-layer graphene oxidation rates at elevated temperatures (up to 2500K) along and across the basal plane are presented. We prepared suspended MLG flakes (thickness range from 10 to 50 nm, lateral sizes from 1 to 10 micron) using liquid phase exfoliation of natural graphite [1] and deposited them onto standard amorphous holey carbon grids by drop casting. Flakes were heated up in air by using the same laser employed for confocal Raman scattering diagnostics, with 473 nm wavelength, power less than 2 mW focused at the flake’s center, and the laser spot of 400-500 nm. Laser heating caused notable reduction of MLG lateral dimensions due to oxidation/burning, with much smaller rates observed for the flake thinning. Further, due to rapid heat distribution along the basal plane (very high in-plane thermal conductivity [2]), and thus even distribution of temperature over the sample area, uniform rates of sample thinning were observed. The dimensions of flakes were estimated before and after laser treatment using scanning electron microscopy images. The flakes’ temperatures were monitored through the downshift of the Raman G-line [3] during all the time of treatment. The thinning rate appeared to be up to an order of magnitude smaller than lateral burning rate in the temperature range from 1500 K to 2300 К (near 0.01 nm/s and 0.1 nm/s at 1800 K, respectively). Above the 2300 K both rates increase fast tending to the same level of 10 nm/s at 2500 K, when the carbon sublimation process is likely to occur.

Comparison was also made with flakes supported over SiO2 substrate, and significant difference in the thinning process was observed. For supported MLG flakes, the process resulted in essentially non-uniform sample thinning (1-2 micron wide holes were produced around the point of heating), in contrast to suspended flakes where uniform thinning over the sample area was observed (see above). The rates of thinning were found to be higher for supported samples. The effect of supporting substrate on graphene oxidation is discussed.

References.

[1] Rouxinol FP, Gelamo RV, Amici RG, Vaz AR, Moshkalev SA. Low contact resistivity and strain in suspended multilayer graphene. Applied Physics Letters. 2010;97(25):253104-3.

[2] Balandin AA. Thermal properties of graphene and nanostructured carbon materials. Nat Mater. 2011;10(8):569-81.

[3] Calizo I, Balandin AA, Bao W, Miao F, Lau CN. Temperature Dependence of the Raman Spectra of Graphene and Graphene Multilayers. Nano Letters. 2007;7(9):2645-9.



347
Electrochemical detection of As(V) by using iron modified carbon paste electrodes
Eduardo Toral-Sánchez, Luis Cházaro-Ruiz, José Rangel-Méndez
Instituto Potosino de Investigación Científica y Tecnológica A.C.

Arsenic (As) is a toxic element that seriously affect human health when this exceeds the maximum allowable limit of 10 μgL-1 in drinking water recommended by the World Health Organization (WHO) [1]. Recently, it was reported the functionalization of activated carbon with iron (Fe) particles and its application to remove As (V) from water. It has been mentioned that Fe (II) complexes have high selectivity and adsorption capacity for As (V) in the pH range of natural water [2].

Nowadays, a considerable number of analytical methods have been developed to detect low concentrations of arsenic in water. Electroanalytical methods, offer high sensitivity, ease operation, low cost instrumentation and portability, allowing to conduct field analysis [3]. Carbon paste electrodes (CPE) modified with metal particles represent an attractive alternative for detection of As.

In this study, a new sensor is proposed for the voltammetric detection of As (V). Graphite was modified with iron particles and then this was used to prepare a CPE, which allowed us to selectively detect As (V) in water.

The sensor contained Fe-modified graphite and silicone oil in a weight ration 55:45. The unmodified material was characterized by physisorption and potentiometric titration. The amount of iron in the graphite powder and its effect on the detection of arsenic was studied. Adsorption experiments were carried with 20-1500 μgL-1 of As at pH 6.5 and 25°C.

According to preliminary results, potentiometric titrations showed that graphite possesses negative charge at pH 6.5, at which the adsorption experiments were conducted, and also that carbonyl groups predominate on its surface. Physisorption analyses revealed that the unmodified material is macroporous and the adsorption isotherms showed that the electrolyte media decreased the As (V) adsorption capacity. On the other hand, differential pulse voltammetric experiments performed by a potentiostat/galvanostat in the three-electrode cell with and without arsenic solution at pH 6.5 and 25°C, presented better arsenic detection in the modified CPE, which was attributed to the iron particles.

Although more studies are needed, these results suggest that once optimized an iron modified CPE can be used to detect low concentrations of As (V) in both underground and drinking water.

Keywords: Arsenic(V), modified carbon paste electrodes, iron particles, DPV, adsorption.

References

[1]World Health Organization, Arsenic in Drinking Water, Fact Sheet No 210,

http://www.who.int/mediacentre/factsheets/fs210/en/index.html (revised December 2012).

[2]Nieto, C., & Rangel, J. (2012). Anchorage of iron hydro(oxide) nanoparticles onto activated carbon to remove As(V) fron water. Water Research 30, 1-10.

[3] Yamada, D., Ivandini, T., Komatsu, M., &et, a. (2008). Anodic stripping voltammetry of inorganic species of As3+ and As5+ at gold-modified boron doped diamond electrodes. Journal of Electroanalytical Chemistry 615, 145-153.



348
Towards Self-Assembling Fullerenes and Metallofullerenes in Coal Fly Ash
Felipe Leãoa,*, Marcio Kronbauera, Silvio Taffarela, Marcos Oliveirab, Luis Felipe Silvaa
a Centro Universitário La Salle, Ensino.
b Environmental Science and Nanotechnology Department, Institute of Environmental Research and Human Development – IPADH

A group of high-As, high-C fly ashes were analyzed by a number of techniques, including high-resolution transmission electron microscopy (HR-TEM), time-of-flight secondary ion mass spectrometry (Tof-SIMS), X-ray photoelectron spectroscopy (XPS), and field-emission scanning electron microscopy (FE-SEM). The sooty carbon is in the form of nano balls with the major fullerenes at C60+, C70+, and C80+, with species at C2 increments from C56+ to C78+. Arsenic and Hg, among other metals, are found in association with the fullerenes, but, with our techniques, it is not possible to determine if the metals are encapsulated by the fullerenes or attached to the side of the structure. TOF-SIMS studies suggest an association of As with the C-amorphous compounds; an association of Pb with oxides, sulfates, and carbon; and Hg with carbon nantubes.



350
Geochemistry of multi-walled carbon nanotubes in coal fire areas.
Felipe Leãoa, Marcio Kronbauera, Silvio Taffarela, Marcos Oliveirab, Luis Felipe Silvaa
a Centro Universitário La Salle, Ensino.
b Environmental Science and Nanotechnology Department, Institute of Environmental Research and Human Development – IPADH

Worldwide coal fires typically generate a diversity organic deposit associated with the venting emission gases. Carbons compounds include amorphous carbon particles, complex nanotubes encapsulating Hg, onion-like structures with polyhedral and quasi-spherical morphology with hollow centers, and metal-bearing multi-walled nanotubes. Mineral and amorphous inorganic phases included glassy Al–Si spheres with associated Pb and Se; nanopyrite grains with trace As and Se; nanohematite with V3+; salammoniac; quartz; Cr- and Pb-bearing jarosite; fibrous pickeringite with surficial natrojarosite; and Cd-, Co-, Mo-, Ni, V-, W-, and Zr-bearing nanospheres. The enrichment of 15N in the soot is associated with the fractionation of NH3 to NH4 in the formation of salammoniac. Selenium, Pb, and Zn are found in relatively high concentrations in the soot and Hg, with 5.68 ppm, has a higher concentration than any coal fly ash.



352
In situ Raman monitoring of the formation and growth of carbon nanotubes via chemical vapor deposition
Karla Reinhold-Lópeza,*, Andreas Braeuera, Bettina Romanna, Nadejda Popovska-Leipertzb, Alfred Leipertza
a Universität Erlangen-Nürnberg, Lehrstuhl für Technische Thermodynamik and Erlangen Graduate School in Advanced Optical Technologies
b Universität Erlangen-Nürnberg, Lehrstuhl für Chemische Reaktionstechnik

Extensive research efforts have been made in the scientific community aiming to understand the nucleation and growth mechanism of carbon nanotubes (CNTs) using the catalytic chemical vapor deposition (CCVD) process. However, after numerous theoretical and experimental investigations, there is still no general agreement about what the deposition determinant steps are and what the influence of the input parameters on the resulting structures is. On this account, we introduce a temporally and spatially highly resolving in situ measurement technique to monitor the formation and growth of CNTs. This approach is based on linear Raman spectroscopy, which enables us to measure simultaneously and in situ the gas temperature and the composition at different locations apart from the substrate surface as well as the structural quality of the growing CNTs. Thus, these investigations can provide a sustained understanding of the CNTs formation and growth mechanism, which for the first time consider experimentally the intermediate reaction steps taking place inside the reactor.

The authors gratefully acknowledge financial support for parts of this work by the German Research Foundation (DFG) which additionally funds the Erlangen Graduate School in Advanced Optical Technologies (SAOT) in the framework of the German excellence initiative.



353
TG/DTA studies on ZnCl2 wood impregnates for activated carbon preparation
NESTOR TANCREDIa,*, MAURICIO GABÚSa, MARÍA IRENE YOSHIDAb, ANDRÉS CUÑAa
a Facultad de Química, DETEMA, Cátedra de Fisicoquímica y Laboratorio de Fisicoquímica de Superficies, Universidad de la República, Uruguay. General Flores 2124, PO Box 11800, CC 1157 Montevideo, Uruguay
b Departamento de Química, Universidade Federal de Minas Gerais, Av: Antonio Carlos, 6627, Pampulha, Belo Horizonte, MG 31270-901, Brazil

Impregnation of wood with ZnCl2 is a treatment used in activated carbon production, and in the liquefaction and fast pyrolysis of biomass. Frequently, the impregnated wood is dried for several hours at temperatures above 370 K and then it is carbonized. Catalytic pyrolysis occurs giving rise to a complex set of reactions. Although a lot of work has been done on this subject, heat changes during the process and the effect of the drying step on the intermediate products have been poorly studied.

In this work Pinus taeda wood sawdust, used as a raw material, was impregnated with ZnCl2 in a mass ratio 1:2. A TG/DTA study was done on: the raw material, the pure ZnCl2, the impregnated wood, the same after drying, the same after drying and washing and the obtained activated carbon. In order to study the mass and thermal changes that occur during the process, elemental analysis, SEM and EDS analysis were carried out. A catalytic torrefaction develops during the drying step in air at 343K. As the pyrolysis proceeds at 743 K, devolatilization of the torrefied product components occurs, at a higher temperature than that of non-impregnated wood and through an endothermic process that include ZnCl2 volatilization. On the other hand, the torrefied product, washed for removing the salt, has a different behaviour during its pyrolysis: the decomposition occurs more slowly, for a larger temperature range, with maximum velocity at a higher temperature than that of the torrefied non washed product. In addition, the process is exothermic, probably similar to that of the exothermic portion of wood pyrolysis, and may involve the decomposition of cellulose, lignin and the solid product of hemicellulose torrefaction. Porous structure accessible to N2 at 77K develops only during the activation step.



355
Carbon Foam from liquefied Products of Wood in Phenol
Zhifeng Zhenga,*, Yunwu Zhenga, Yuanbo Huanga, Mingkun Liua, Hui Panb
a Key Laboratory of Forest Resources Conservation and Utilization in the Southwest Mountains of China (SWFU), Ministry of Education; College of Materials Engineering, Southwest Forestry University, Kunming 650224, China
b Calhoun Research Station, Louisiana State University AgCenter, Calhoun, Louisiana 71225, USA

Carbon foam was successfully prepared from phenolic resin synthesized with liquefied products of wood and formaldehyde under low alkali condition. Firstly, the liquefied product was obtained at the liquefaction of wood in phenol with sulfuric acid as a catalyst. Then phenolic resin foam was synthesized with the liquefied product and formaldehyde at the starting phenol/formaldehyde/NaOH molar ratio of 1/1.8/0.02 and foamed at 80 ℃ with hydrochloric acid as a catalyst. The consequent resin foam was carbonized at 800 ℃. The carbon foams obtained at different phenol replacement by wood part were investigated. They showed good absorption ability for iodine and methylene blue. SEM showed that the carbon foam had honeycomb structure, and the pore size on the wall was about 200-500 nm.



357
Raman analysis of the micro-structure and confirmation by oxidation behaviors of the commercial carbon fibers
Kap Seung Yanga,*, Dae Ho Kimb, Bo-Hye Kimc, Yun Hyuk Bangd, Sung Ryong Kimd
a Professor
b Graduate student
c Research Professor
d Research director

The micro-structure and defect of the carbon fibers are the determining factors of their physical and mechanical properties. The R values (Intensity of D/Intensity of G band) were determined by the Raman analysis and the values were visualized with various colors. The carbon fiber is sensitively oxidized depending on the contact area of the micro-domain of the carbon fiber at above 500℃ and the property limits their application condition. This study includes the oxidation dependence on the micro structures of the carbon fibers. In general, the more crystalline fibers, the higher the oxidation resistive was. The diameter reduction ratio value at 50wt% burn-off and surface morphologies deduced to 4 classifications of the oxidation mechanism as: oxidation from the surface of the fiber due to its dense microstructure as high modulus polyacrylonitrile(PAN) based fiber; oxidation from the large crystallite surface through the diffusion of oxygen along the pores among as high modulus pitch based graphitized fiber; oxidation from the relatively small crystallite surface due to the porous structure with low crystallinity as rayon based carbon fiber; and oxidation showing the characteristics of the medium of 1st and 2nd cases as PAN based carbon fiber.



358
Tailoring the porosity of biomass-based activated carbons intended for methane storage
Marcos Juliano Prauchnera,*, Francisco Rodríguez-Reinosob
a Brasília University, Brasília, Brazil
b Alicante University, Alicante, Spain

Activated carbon is considered to be the general adsorbent due to the large range of applications. For the purpose of gas storage, a high adsorption capacity on a volumetric basis is required. In order to improve it, the adsorbent should present a porosity as high as possible with the pore size distribution centered at an optimum value that permits to maximize the density of the adsorbed phase. In the particular case of methane, this value is assumed to be slightly above 0,8 nm - twice the dimension of the molecule. Further, the material should present an elevated compactness in order to minimize the occurrence of waste spaces.

The present work concerns the development of a methodology for producing biomass-based activated carbons with improved methane storage capacities. The starting material was a granular dried endocarp of coconut shell. The procedures employed were physical activation with CO2 and/or chemical activation with H3PO4 or ZnCl2.

The results showed that the physical process permits to tailor the pore size distribution more accurately. This way, carbons with high microporosity and surface area were achieved. However, they presented relatively low packing densities due to the occurrence of large empty spaces that originate from the structure of conductor vessels present in the botanical structure of the precursor. Therefore, the volumetric adsorption capacities of physically activated carbons were reduced. In turn, H3PO4 and ZnCl2 promoted a redistribution and reorganization of the lignocellulosic material during early carbonization stages, leading to the suppression of the above mentioned empty spaces. Therefore, a positive effect on the volumetric adsorption capacity took place. On the other hand, the employment of large chemical proportions needed for obtaining high activation degrees led to the broadening of the pore size distribution, which compromised the density of the adsorbed methane.

These features suggested a more efficient methodology for producing biomass-based activated carbons with improved gas storage capacities: the combination of a relatively weak chemical activation with H3PO4 or ZnCl2, only sufficient to suppress the presence of empty spaces that originate from the precursor botanical structure, followed by physical activation with CO2 to appropriately develop a structure of narrow micropores. This methodology permitted to obtain granular carbons with methane adsorption capacities nearing 100 V/V.

The present work permitted to elucidate several aspects related to the physical and chemical activation of biomass derivatives with CO2 and H3PO4 or ZnCl2, respectively. This comprehension made possible to develop a methodology that has permitted the synthesis of granular carbons with methane adsorption capacities that might be considered reasonable for applications such as natural gas transportation in mobile pipelines.



359
Partially carbonized furfurilic resin powder: a new route to obtain vitreous carbon
Alvaro Jose Damiao, Fábio Dondeo Origo, Fernanda Nascimento, Marcos Valentim
Instituto de Estudos Avançados

The traditional route to obtain Monolithic Vitreous Carbon (MVC) leads to a limit of 7 mm in thickness. Due to a large loss of volatiles, most part of the samples break during the carbonization process, even when very slow temperature ramps are used. This work presents a new route to obtain vitreous carbon (VC) that allows thicknesses higher than 21 mm. The process is based on the Powder Metallurgy Process and higher carbonization temperatures rates can be used without breaking the samples. The idea is to divide the carbonization process in two steps. In the first step, the furfurilic resin was catalyzed and partially carbonized at 600 ºC as in the traditional route. The samples are then ball milled, so higher temperatures rates can be applied during the previous partial carbonization. The material is then sieved using sieves with different mesh numbers, resulting in powder classified from less than 37 μm, from 37 μm to 44 μm, and so on, till larger than 149 μm. Using graphite (3%) as lubricant, the powder is uniaxially and isostatically pressed (400 MPa). Higher temperatures rates can be used on the second carbonization step (1100 ºC), since most part of the volatiles went out in the first carbonization step and its rest is eliminated through the voids. All carbonization steps were performed in nitrogen atmosphere. The samples presented higher strength, what was not expected. This development was associated to a project to obtain lower specific mass mirrors for space embedded imaging devices. Results of apparent density and surface roughness will be presented.



360
Activated carbon production using a Cerrejón Coal as row material
Jose Rincona,*, Daniel Balléna, Lisbeth Vallecilla Yepeza, Pedro Guevaraa, Nestor Monroyb
a Centro de Desarrollo Industrial – Tecsol
b Cerrejón Coal Company

Colombia is the major coal producing country in Latin America. It has thermal coal in the north, near to the Caribbean Sea, and coking coal is located in the central region. Normally, low ash coking coal is used for the activated carbon producing but the intrinsic ash content of this coal in Colombia is over 5%. Cerrejón coal, thermal coal, can be beneficiated to give ash content lower than 3%. So, the main objective is to evaluate the possibility of use this coal to produce commercial activated carbon.

In the present work, we tested two routes to obtain the activated carbon. The first route was physical activation in two steps: carbonization and steam activation- The results show that three hours of residence time at 1023 K gives an activated carbon with an Iodine number of 1034 and methylene blue index of 6.0. The second route was chemical activation with potassium hydroxide- the results show Iodine numbers from 1000 to 1771 at 873 K – 1073 K with the relation KOH/Coal: 1/1 and one hour of residence time.



362
Synthesis of ultrathin graphite films with controlled preferential orientation of carbon layers
Yasushi Soneda, Genki Odahara, Noriko Yoshizawa, Masaya Kodama
National Institute of Advanced Industrial Science and Technology (AIST)

Ultrathin graphite films of 20 mm square with the thickness between 30 and 100 nm were synthesized by the carbonization of poly-benzimidazobenzophenanthroline ladder (BBL) polymer. BBL polymer was soluble in strong acid such as methanesulfonic acid (MSA) or trifluoromethanesulfonic acid (TFMSA) and those solutions were able to form a polymer coating on a suitable substrate by the spin-coating process. Spin-coated BBL polymer on a glass substrate was subjected to vacuum dry and rinse in base solvents to complete the elimination of acid solvent. Then, BBL polymer thin films on the substrate were covered with PMMA by subsequent spin-coating and peeled off from the substrate as a double layer thin film. The BBL/PMMA double layer polymer films thus obtained were sandwiched in between two graphite plates for the heat treatment in inert atmosphere.

The heat treatment of the pre-carbonized polymer film at 2800ºC yielded the ultrathin graphite films which possess the light transparent and the self-standing characteristics. The resultant graphite ultrathin film prepared from the TFMSA solution of BBL polymer were composed of the parallel orientation of carbon layer stacking to the film surface, although the graphite ultrathin film from MSA solution showed the perpendicular stacking of carbon layers against to the film surface.

The anisotropy of texture in graphite ultrathin films with both preferential orientations is evaluated with different technique such as XRD, Raman, TEM, SEM, transport properties and mechanical behavior. The graphitization behavior of those films is also examined with different heat treatment temperatures up to 3200 ºC.



363
Adsorption Behaviors of Heavy Metals Cd(II) and Pb(II) on Activated Carbon and Activated Carbon Fiber
Kim Dae Hoa, Kim Doo Wona,*, Kim Bo-Hyeb, Yang Kap Seungc, Lim Young-Kyund, et al.
a Department of Advanced Chemical Engineering, Chonnam National University, Gwangju, 500-757, Korea
b Alan G. MacDiarmid Energy Institute, Chonnam National University, Gwangju, 500-757, Korea
c Department of Polymer & Fiber System Engineering, Chonnam National University, Gwangju, 500-757, Korea
d Microfilter Co., Ltd, 162-1, Sansu, Deoksan, Jinchun, Chung-Buk, 365-842, Korea

The adsorption characteristics of Cd(II) and Pb(II) in aqueous solution using granular activated carbon (GAC), activated carbon fiber (ACF), modified ACF (NaACF), and mixture of GAC and NaACF (GAC/NaACF) has been studied. The surface properties, such as morphology, surface functional group, and composition of various adsorbents were determined by using X-ray photoelectron spectroscopy (XPS) and scanning electron micrograph (SEM) measurements. The specific surface are, total pore volume, and pore size distribution were investigated by using nitrogen adsorption, Brunauer-Emmett-Teller (BET), and Barrett-Joyner-Halenda (BJH) methods. In this study, the NaACF showed high adsorption capacity and adsorption rate for the heavy metal ions, due to the improved ion-exchange capabilities by more oxygen functional groups. Moreover, the mixture of GAC and NaACF was used as adsorbent and determined the interaction of adsorbent-adsorbate in competitive two adsorbents.



369
ADSORPTION OF NITROGEN AND SULPHUR COMPOUNDS OF DIESEL FOR ACTIVATED CARBONS IMPREGNATED WITH COPPER BEFORE AND AFTER SOLVENT REGENERATION
Caroline Schmitta,*, Carlos Yamamotoa, Sandra Chiarob
a Universidade Federal do Paraná
b CENPES/PETROBRAS

Following global trends of minimizing the emission of pollutants from burning fossil fuels, started in Brazil the Control Program Air Pollution by Motor Vehicles (PROCONVE). In January 2013 come into force on stage when the Diesel S50 (50 ppm sulfur) will be replaced by Diesel S10 (10 ppm sulfur). Among the technologies that can complement or replace the Hydrodesulfurization, currently used to remove sulfur from diesel, the adsorption technology showing a low-cost alternative because requires low pressure and temperature. However, adsorption is only feasible commercially if an efficient regeneration is applied.

Based on this problem, two commercial coconut babaçu activated carbons (CAB-I and CAB-II), both mesoporous impregnated CuCl2 were used as adsorbents to selective removal of sulfur and nitrogen compounds from diesel S200, product of Hydrodesulfurization. The adsorption of nitrogen compounds was evaluated due the inhibitory characteristic that exhibit on the desulfurization. First the carbons were impregnated with CuCl2 solution. Then held adsorption, where 20 ml of Diesel were kept for 24 h with 2 g of dry carbon. The adsorption was performed at 40 °C and agitation of 150 rpm.

Furthermore, recovery of the adsorption capacity after regeneration was investigated with toluene. The adsorbents used in the first adsorption were filtered and after removal of excess Diesel, 20 mL of desorbent was added to activated carbon. The regeneration was performed at 33 °C and agitation of 150 rpm for 30 minutes. The adsorption capacity was determined after regeneration and recovery of adsorptive capacity was evaluated.

The carbon CAB-I removed 48,8% of the sulfur present in diesel, with the adsorptive capacity of 1,01 mg-S/g-CA. Already CAB-II was able to remove about 22,6% of the sulfur compounds from the diesel presenting a adsorptive capacity of 0,47mg-S/g-CA lower than the CAB-I, probably due to the lower concentration of micropores.

The ability of removal of nitrogen compounds from both carbons was greater than the capacity of removing sulfur, probably due to the presence of oxygenates in the carbon surface. The carbon CAB-I removed 93.8% of the nitrogen Diesel, with a adsorptive capacity of 1,93 mg-N/g-CA. Since the CAB-II removed 70,7% of nitrogen with an adsorption capacity of 1,45 mg-N/g-CA. The presence of mesopores may have contributed to the adsorption of nitrogen, favoring the diffusion.

After regeneration with toluene, the greater recovery adsorption capacity was obtained for CAB-I, with 58,7% recovery for sulfur and 83,35% for nitrogen. Both carbons had higher recovery of adsorption capacity for nitrogen, as with virgin carbon. It was possible to recover 31,6% of the adsorption capacity for sulfur and 54,8% for nitrogen coal CAB-II.

The carbons presented promising for removal of contaminants from Diesel, and the CAB-I showed the best performance. The reuse after regeneration with toluene was shown as an alternative to reuse of adsorbents.



370
Comparison the removal capabilities of sulfur and nitrogen compounds from diesel oil through adsorption by different lots of activated carbons impregnated with copper chloride.
Rubia Mariatha,*, Carlos Yamamotoa, Sandra Chiarob
a UFPR
b Petrobrás

The production of sulfur and nitrogen oxides, environmentally damaging, is worrisome due mainly to the large consumption of diesel for freight transport. To improve the removal of sulfur compounds such as dibenzothiophene and 4-metildibenzothiophene, and thus reach the limit of sulfur content in diesel, established by CONAMA Resolution n0 415/2009, we analyzed the desulfurization by adsorption using activated carbon impregnated with copper. The reactions occur at atmospheric pressure and room temperature. The activated carbon has a good adsorption capacity due to its surface area, where there are functional groups that facilitate the removal of sulfur and nitrogen compounds, besides having a low cost. The impregnation with copper helps in increasing the adsorption capacity of the activated carbon. Two types of carbons from coconut shell were used, named CAC3 and CAC2, differentiated in their particle sizes and the production process. The impregnation of these carbons was carried out with copper chloride 0.52 M. After impregnation the adsorption was performed using 2 g of activated carbon to 20 ml of diesel S250, at temperatures of 40 and 70 0C. The adsorption kinetics showed that CAC3 obtained the best performance in removing sulfur and also nitrogen. But CAC2 showed significant results for nitrogen removal too. This affinity, both CAC3 and CAC2, by nitrogen compounds is a great advantage, because there is a competitive reaction with the sulfur removal compounds in hydrodesulfurization processes. It was not evidenciated the influence of temperature on adsorption reactions.



372
PROCESSES TO CONTROL THE POLLUTION BY EMERGING WATER CONTAMINANTS
Sandrine DELPEUX-OULDRIANE, Mickael GINEYS, Nathalie COHAUT, François BEGUIN
CNRS-CRMD-Orleans University

During the last decade, thanks to the improvement of analytical techniques, a wide variety of micro pollutants, like reproductive hormones and pharmaceuticals, have been detected at trace concentrations in wastewater effluents [1-3]. For tertiary water treatments, activated carbons (AC) efficiency is already well established, particularly at low pollutant concentration. ACs appear as the most competing adsorbents with adsorption levels reaching nearly 100% without generating by-products. Especially, due to their microtexture, activated carbon cloths (ACC) are ideal candidates for an adsorption purpose as they show minimal diffusion limitation and therefore high adsorption rates. However, the lack of in-situ regeneration potentialities is still to be overcome and new techniques have to be developed in this sense. In previous works, we have shown that desorption of organic pollutants loaded on ACC, could be conducted successfully by applying a cathodic polarization of the carbon electrodes, therefore leading to a fast regeneration of its porosity [3, 4]. In the present work, the adsorption properties of some pharmaceuticals residues have been investigated using activated carbon cloths having different nanotextural and chemical properties. An electrochemical polarization has been applied to perform the reversible desorption of adsorbed species and the regeneration ability has been characterized by gas adsorption. The involved mechanisms have been examined carefully in light of nanoporous texture and surface functionality of carbons but also of adsorbat speciation. Especially, porosity and concentration effects have been studied. Additionally, HPLC measurements were conducted in order to determine the impact of the polarization conditions on the stability of organic pollutants and the degradation rate. The regeneration of ACC loaded with biologically active molecules could be achieved within a short time, with levels reaching nearly 95%, depending on the targeted pollutant. It has been demonstrated that water decomposition can help by favoring the dissociation of surface groups and therefore enhancing electrostatic repulsions. We assume that reversible desorption of adsorbed species is performed through electrostatic repulsions, reinforced by the presence of dissociated carbon groups and the electrical field. The contaminants desorption or degradation abilities depend strongly on their physico-chemical characteristics, i.e. pKA and solubility. It appears that electrochemical techniques can either be conducted to perform the reversible desorption of induced charged molecules or their desorption-degradation, depending on the polarization parameters. Such techniques offer great potentialities for the development of soft and controlled in-situ regeneration processes and could find applications in industrial treatments for chemical industry or hospitals effluents. [1] Huerta-Fontela M., Galceran M.T., Martin-Alonso J., Ventura F., Sci. Total. Environ. (397) 2008, p. 31-40. [2] Report of the Metropolitan Agencies: « Pharmaceuticals in the Water Environment, 2010. [3] T. Deblonde, C. Cossu-Leguille, P. Hartemann, Int. J. of Hyg. and Env. Health (214) 2011, p. 442-448 [4] C.O. Ania, F. Béguin, Water Research (41) 2007, p. 3372-3380. [5] S. Delpeux-Ouldriane, N. Cohaut, F. Béguin, Proceedings World Carbon Conference, Biarritz (France) June 2009.



375
Band structure calculation of graphane using LDA-1/2 method
Cássio S. Sousa, Lara K. Teles, Ronaldo R. Pelá, André J. C. Chaves, Marcelo Marques, et al.
Instituto Tecnológico de Aeronáutica

Graphene is one of the most studied materials nowadays. Its carbon constitution and a two-dimensional structure brings a new role of possibilities for new technologies and science itself. One of these outspreads is graphane [1], a hydrocarbon built from graphene, whose first theoretical analyses showed a gap presence [2], which may be really helpful for electronic devices and semiconductors. Using the local density approximation (LDA), a minimum, direct gap of 3.4 eV was found at point Γ of the stable chair conformation [2] of graphane, where hydrogen atoms are attached to carbon atoms in alternate, opposite sides along the graphane structure. However, standard DFT approaches using LDA and others exchange correlation potentials obtain an underestimation of energy gap value for semiconductors. Several methods for overcoming these limitations have been proposed, as the most precise and important of them being GW approximation [3], in which one considers the energies of quasiparticles and calculate the electron self-energy in terms of perturbation theory. Very recently in 2008, our group has proposed a novel method, called LDA-1/2 (or GGA-1/2) [4], that obtains very good results for energy gap in semiconductors, with the great advantage of no extra computational effort compared with standard DFT approaches. A further analysis using LDA-1/2 for graphane approximation showed a minimum, direct gap of 5.6 eV also at point Γ, which agrees with GW calculations made for the same conformation of graphane (5.4 eV) [5].

[1] D. C. Elias et al., Science, Vol. 323, no. 5914, pp. 610-613, 1167130 (2009).

[2] J. O. Sofo, A. S. Chaudhari and G. D. Barber, Phys. Rev. B 75, 153401 (2007).

[3] M. S. Hybertsen and S. G. Louie, Phys. Rev. Lett. 55, 1418 (1985).

[4] L. G. Ferreira, M. Marques and L. K. Teles, Phys. Rev. B 78, 125116 (2008).

[5] S. Lebègue, M. Klintenberg, O. Eriksson and M. I. Katsnelson, Phys. Rev. B 79, 245117 (2009).



377
Influence of textile PAN fiber oxidation degree on activated carbon fiber produced by ultrafast process.
Jossano Saldanha Marcuzzoa,*, Choyu Otanib, Heitor Aguiar Polidoroc, Satika Otanic
a ITA - Instituto Tecnológico da Aeronáutica / Multivácuo Aeroespacial Ltda
b ITA - Instituto Tecnológico da Aeronáutica
c Multivácuo Aeroespacial Ltda

Using textile PAN fibers oxidized at two different conditions (S – strongly and W – weakly), this work aims the study of the micropores formation on activated carbon fiber (ACF) by ultrafast activation process, characterized by use of 100 °C/min heating rate and 2.5h total process. Both fiber samples (0,4 m length and 6 g) were carbonized at 900°C-20 min in argon atmosphere, and subsequently activated in CO2 atmosphere at 1000°C-50 min. The pore structures of the samples were evaluated by N2 gas adsorption isotherm at 77K, while the mechanical properties of fibers were measured before and after carbonization-activation process. The main considered results are focused on final ACF surface area (1000 m2/g by DFT) and pores sizes distribution (PSD) calculated by NLDFT model. In spite of high heating rate applied to ACF production and the differences observed in oxidizing condition of PAN fiber, both ACF presented similar micropores distribution function, unless the fact that S type fiber produces micropores with diameter less than detection limit of the method (< 0,5nm). This result leads to the conclusion that the oxidation condition of PAN influences on minimum diameter of micropores available on the ACF surface.



378
Aerographite – a network of tetrapod-shaped and coherent interconnected graphite tubes. – Utilization of integrated bridges of graphite for exceptional specific mechanical and electrical properties, due to a highly tailorable CVD-approach.
Matthias Mecklenburga,*, Arnim Schuchardtb, Rainer Adelungb, Karl Schultea
a Hamburg University of Technology (TUHH); Insitute for Poylmers and Composites
b University of Kiel (CAU); Institute for Materials Science - Functional Nanomaterials

Utilization of graphite-based networks, as e.g. CNT-sponges, few-layered graphene - or graphite-oxide-based aerogel assemblies, is often limited due to a lack of real structural integrity. A highly porous structure, with building elements of graphite in all three dimensions, but with direct interconnections would deliver much more reliable pathways for electrical conduction and mechanical load transfer, than mechanisms of just mechanical entanglement or weak van der Waals bonds, as in other highly porous carbon nanotube or graphite-based aerogels recently reported. CVD growth, which can form coherent layers of graphite over a network of small building-elements, is highly preferred.

If one would theoretical think a framework, which shall meet the demands of: (a) isotropic mechanical load bearing capacity for various load cases, but which is (b) tolerant to high deformations and which is (c) highly lightweight, one would end by a construction of inner building-elements, with long, rigid, tubular, hollow arms of large diameter and low wall thickness, oriented in all three dimensions. These tubes would bridge towards their next neighbors and forming strong nodes. - We tried to transfer this construction principle to graphite in the order to highly improve the utilization graphite-based materials excellent mechanical and electrical properties in manifold applications.

Here we introduce a novel CVD-approach, which leads to the desired inner bridges of a graphite aerogel: Aerographite is a hierarchical carbon nanomaterial, which is formed by a covalently interconnected 3d-network of micrometer-sized tetrapods of thin-walled graphite tubes. The first time we introduced, that networks of micrometer-sized ZnO tetrapod-like particles can be used as substrate for the deposition of thin-layered graphite. This approach benefits from the well-known highly-adjustable geometries of ZnO particles, sintering bridges between the used template particles, and the new possibility of simultaneous removal of all the template material without any wet-chemical treatment. This results in a single-step CVD-process which can potentially be up-scaled to large volumes. Network morphology, wall thickness and also carbon species (glass-like or graphitic) of Aerographite can be tuned by template and synthesis parameters. Even low-density Aerographite variants of just 200 µg/cm³ can handle tensile forces. Despite of the ultra-low density a high light absorption, excellent specific electrical conductivity and an extraordinary high mechanical robustness and flexibility is enabled.

In the lecture we will highlight the synthesis approach, and introduce several derived structure variants using TEM, SEAD, EELS, XRD and Raman Spectroscopy. Structural features of Aerographite will be discussed in detail, together with resulting mechanical and electrical properties. Additionally, we give insight into intermediate reaction states by TEM and SEM observations to discuss its growth and formation. Many of today's and future energy key-technologies, like batteries or super capacitors call for mass producible, lightweight, flexible and electrically conductive materials. Aerographite is robust under tension and compression loads, but highly accessible for electrons and ions and electrical contacts are not altered by penetrating polymers or solvents. - In order to demonstrate practical application, first measurements on Aerographite based double layer capacitors will be presented.



380
Bindered anthracite bricks as fuel alternative of metallurgical coke: full scale performance in a cupola furnace.
Cesar Nieto Delgadoa,*, Fred S. Cannonb, Paul David Paulsenc, James C Furnessc
a Department of Civil and Environmental Engineering, The Pennsylvania State University.
b Department of Civil and Environmental Engineering, The Pennsylvania State University,
c Furness-Newburge Inc

This work has focused making bindered anthracite bricks that perform similar to metallurgical coke that is employed in cupola furnaces. The anthracite bricks were bindered with lignin, biomaterials, and silicon-silicate. These binderes gave the bricks mechanical strength at the full spectrum of temperatures encountered in a foundry cupola—from ambient to 1600oC. The bricks burned as hot and as fast as conventional metallurgical coke, while achieving a 15-20% less life cycle energy consumption per ton of metal melted. The mechanical properties, measured as unconfined compressive strength of the anthracite bindered bricks were superior to the metallurgical coke. Diverse production parameters where studied to manufacture the bricks in demonstration-scale and ultimately full-scale production. During two full-scale demonstrations of this technology that employed 8 tons of these bricks, the anthracite bricks perform similar to the metallurgical coke, while the foundries substituted up to 25% of the coke with the bricks. Images taken through the tuyere windows (where oxygen-enriched air was lanced into the bottom of the cupola) demonstrated that the anthracite bricks could reach the melting zone in tact--without having fallen apart. Also, once these bricks reached the level of the tuyere windows, they burned faster in the oxygen-enriched air than did conventional coke. The presentation will also include nano-scale analyses and images of the polyaromatic structures in the brick materials after they have experienced the spectrum of temperatures that occur in cupolas.



381
Nanostructured porous carbon with high loading sulfur as cathode for high performance lithium sulfur battery
Feng LIa,*, Guangmin Zhoua, Dawei Wangb, Li-chang Yina, Lu Lia, et al.
a Shenyang National Laboratory of Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang110016, China
b ARC Centre of Excellence for Functional Nanomaterials, AIBN, The University of Queensland, Brisbane, Qld 4072, Australia

Elemental sulfur, which has a high abundance in the Earth’s upper continental crust, has various functional applications. Sulfur can be used as cathode for the high energy lithium sulfur batteries, which have extraordinary high specific energy dramatically outperform those of lithium ion batteries. However, various problems hinder the practical use of this attractive high-capacity cathode material. These challenges mainly include the insulating nature of sulfur that retards its reduction, leading to low power, and a short cyclic life due to the dissolution of polysulphide intermediates in electrolyte. Carbon materials with high porosity and good electrical conductivity are the best choice to overcome the aforementioned sulfur cathode challenges. Herein, we reported that the selective immobilization of sulfur in sub-nanometer micropores results in an ultrafast and durable cathode, which is from the confinement of sulfur in sub-nanometer micropores, meso-macroscale lithium ion transport and electron conduction in graphitic structure can be realized in a carbon system. Therefore we can obtain the carbon nanotube/sulfur cathode, which has a high electrical conductivity of 800 S m−1 that is ~30 orders of magnitude higher than sulfur, a long life of over 100 cycles, and a high discharge capacity of 712 mA h g−1sulphur at an ultrafast rate of 6 A g−1sulphur. These results demonstrate the great potential of this nanostructured sulfur/carbon composite as a cathode for Li-S batteries with ultrafast charge/discharge performance and long life.



383
Direct polymer infiltration of graphene aerogels for the production of conductive nanocomposites
Han Hu, Zongbin Zhao, Quan Zhou, Ying Zhou, Jieshan Qiu
Carbon Research Laboratory, Liaoning Key Lab for Energy Materials and Chemical Engineering, State Key Lab of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology

As the strongest and most conductive material, graphene has been demonstrated as one of the most effective filler to enhance the electrical and mechanical properties of polymer by integration of graphene sheets into the matrix. For the sake of formation of percolation network of fillers in polymer host, strategies such as functionalization, high shear mixing and long-time sonication are generally required, which may result in deterioration of properties of the fillers. It still remains a great challenge to efficiently fabricate continuous network of graphene in polymer matrix at low concentration. Herein, we present a solution to this challenge by direct infiltration of epoxy fluid into graphene aerogel compromising of interconnected graphene sheets with ultralow density. The presence of aerogel makes the composite conductive at filler content as low as 0.4 wt.%. Composites with different morphologies such as circular cylinder, triangular prism, quadrangular prism, etc. can be easily achieved by incorporation of polymer into aerogels with different shapes. The strategy developed here may inspire new possibilities to efficiently create graphene-polymer compositions with excellent properties.



385
Synthesis and supercapacitor performance of Morphology-controlled Ni-doped Carbon Particles in Resorcinol-Formaldehyde Inverse emulsion Polymerization System
Lei Qian, Song Huaihe, Chen Xiaohong
State Key Laboratory of Chemical Resource Engineering, Key laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology

Ni-doped Carbon Particles with controlled morphology were synthesized by carbonization of Ni-doped Resorcinol-formaldehyde (RF) aerogel particles extracted from an inverse emulsion polymerization system. Ni was introduced into the reaction system by directly adding nickel salt into the RF solution. The morphology and size distribution of Ni-doped carbon particles can be controlled by adjusting nickel salt concentration and stirring speed. It was found that metal salt addition can change the morphology of RF carbon particles from spheres to hemispheres, hollow spheres and irregular bladder. Ni particles were distributed uniformly in the carbon network. The morphology and structure of the Ni-doped carbon particles were investigated by TEM, HRTEM, XRD, FI-IR and BET measurement. The electrochemical performance was tested when using these carbon particles as the electrode material for supercapacitors.



386
Anomalous capacitive increase of graphene nanosheets with extremely low surface area
Xian Du, Huaihe Song, Xiaohong Chen, Kang Guo
State Key Laboratory of Chemical Resource Engineering, Key laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029, China

Carbon materials are widely applied as electrodes for supercapacitors, mostly ascribed to the high effective specific surface area (SSA) (500-1500 m2 g-1) accessible for the electrolyte ions to form large electric double-layer for energy storage. Graphene, a two-dimensional carbon material with single atomic thickness, is the basic structural unit for graphitic materials by maximum stripping graphite. Since the single graphene layer was detected in 2004, it has become an excellent candidate for electrode of electric double-layer capacitor (EDLC) due to the large intrinsic surface area (2630 m2 g-1) of graphene. Optimizing the preparation of graphene nanosheets could potentially improve performance by enlarging the actual surface area of graphene electrode, but until recently, no literatures had studied whether the SSA was the only main capacitive resource for graphene electrode. Ball-milling graphene nanosheets in Ar atmosphere for different time (0-21 h), we generated surface areas from 25 to 665 m2 g-1 and studied double-layer capacitance in KOH electrolyte. The milled graphene nanosheets for 21 h had a severely low SSA (25 m2 g-1) but a higher capacitance of 183 F g-1 than that of raw graphene nanosheets (665 m2 g-1). The results challenge the long-held axiom that large specific surface area is the necessary prerequisite for electrode materials of EDLC.



388
Characterization of nanoporous carbons from X-ray Scattering, Transmission Electron Microscopy and (N2, CO2) adsorption.
Pascaline Préa,*, Andrei Shiryaevb, Jean-Nöel Rouzaudc, Albert Voloshchukb
a (1) GEPEA, UMR CNRS 6122, Ecole des Mines de Nantes, 4 rue Alfred Kastler, 44307 Nantes Cedex 03, France
b (2) A.N. Frumkin Institute of Physical Chemistry and Electrochemistry of Russian Academy of Sciences, Leninsky pr. 31, Moscow 119071, Russia
c (3) Laboratoire de Géologie, Ecole Normale Supérieure, UMR CNRS 8538, 75231 Paris, France

The efficiency of the adsorption processes using nanoporous carbons for bulk gas separation or purification is mainly conditioned by their microporosity features. As these materials exhibit a highly disordered nanostructure, with a carbon backbone formed by assemblages of defective graphene sheets with cross-links, the pore morphology is irregular, leading to more or less broad pore size distributions and possibly partially closed porosity. The aim of the study was to explain the differences observed in the adsorption capacities (i.e. open pore volumes) of a variety of activated carbons by collecting some information about their structure throughout the combination of two characterization methods: Small and Wide Angle X-ray Scattering (SWAXS) and Transmission Electron Microscopy (TEM) image processing.

The set of adsorbents under investigation includes different commercial activated carbons, a carbon molecular sieve and carbons produced from a synthetic monomer (furfurol) at different degrees of activation. The adsorption capacities of the materials were determined for N2 at 77K, and CO2 at 273K in the pressure range from 10-7 up to 1 atm. The isotherm data, completed with Hg intrusion measurements, were used to estimate pore volumes and pore size distributions (PSDs) over the range from ultra-micro (less than 0.7 nm) up to mesopores (up to 50 nm). The nanostructure of the materials was observed by TEM under high resolution lattice fringe mode. The TEM images were processed with a home-made software [1] so that the least and higher disordered parts of the structure could be extracted and their geometry characterized throughout a variety of parameters, such as fringe length, tortuosity, local curvature radii... The most ordered parts of the structure were identified as double layer stacks and continuous domains (multiple layer stacks with a common orientation) which size and surface density could be determined. In addition probability density functions of the effective spaces separating the different entities were measured and could be compared with micro and ultra-micro pore size distributions. Furthermore, SWAXS patterns were recorded using monochromatic CuKα-radiation in broad angular range (scattering vectors s between 0.1–27 nm-1) using dedicated diffractometer SAXSess (Anton Paar). Kratki collimation scheme was employed; desmearing was performed using standard software. The scattering curves were interpreted in the low s range as resulting from the existence of large substructures entities (continuous domains and possibly mesopores) whilst the large s range was assumed to be representative of both the closed and open microporosity. Accounting for TEM image processing and adsorption data, interpretation of the SWAXS curves could be consolidated and porosity features clarified.

[1] Pré P et al., 2013, Carbon, 52, 239-258.


391
Active sites of nanoshell-containing carbon cathode catalysts for proton exchange membrane fuel cells
Ozaki Jun-ichi, Kusadokoro Sayaka, Maie Takuya, Kannari Naokatsu
Gunma University

Realization of low-carbon-dioxide emission society by utilizing hydrogen as an energy carrier requires practical implementation of fuel cells. Particularly, proton exchange membrane fuel cell (PEMFC) is the most expected type of the fuel cells, since it can be loaded on electric vehicles that will contribute to a large amount of reduction of carbon dioxide emission. However, the cost problem due to the cathode platinum catalyst retarded its implementation. Therefore, exploring non-platinum cathode catalyst has interested material scientists and fuel cell engineers to spur the installation of PEMFC on the electric vehicles.

There have been many types of non-platinum cathode catalysts, such as surface metal complexes supported on carbon substrates, nitrogen doped carbons and several types of ceramics containing high-melting–point transition metals. We have reported the higher activity of nanoshell containing carbon (NSCC) for oxygen reduction reaction (ORR), the cathode reaction of PEMFC. The active sites of NSCC have not been directly clarified, since NSCC is composed of nanoshell structure (NS), which is hollow shell-like structure with diameters ranging 20-50 nm, and amorphous carbon moiety (ACM) that has not been influenced by the nanoshell forming transition metal catalysts; although NS has been speculated as the component holding the active sites for ORR. In the present study, we carried out the condensation of NS by selective removal of ACM with hydrogen peroxide, and to reveal NS responsible for the ORR activity.

Carbonization of a precursor composed of novolac type phenol-formaldehyde resin (PFR) and cobalt phthalocyanine at 1000oC for 1h gave NSCC. The carbonized sample was pulverized with a ball mill followed by acid-wash treatment to remove the surface metal species, which is referred to as un-NSCC. The obtained un-NSCC was subjected to H2O2 treatment at 100oC under reflux condition for 2 h. After the treatment, the sample was thoroughly rinsed with deionized water and then dried. The retrieved sample is referred to as H2O2-NSCC. In order to remove the surface functionality formed during the H2O2 treatment, H2O2-NSCC was heat-treated at 850oC in a nitrogen stream (HT-H2O2-NSCC).

The selective removal of the ACM in H2O2-NSCC was confirmed by the studies of scanning electron microscopy, Raman spectroscopy and X-ray diffraction. The ORR activity of the sample was found to be deteriorated by the H2O2 treatment, which does not agree with our anticipation that the active sites located on NS. A temperature-programmed desorption study of H2O2-NSCC revealed the formation of a plenty amount of oxygen surface functionalities. Heat treatment at 850oC was the maximum temperature that reduced the amounts of the surface functionality to the original level without influencing the carbon structures. The treatment induced the ORR activity exceeding the original un-NSCC on weight basis, indicating the effect of NS condensation by the removal of ACM. A comparison of the normalized ORR activities based on mesopore surface areas of the un-NSCC and HT-H2O2-NSCC revealed that the removal of ACM resulted in the formation of effective path for mass transfer, of which walls possessed active sites that had been hindered by the presence of ACM.



394
Sculpture Preparation of Mesoporous Carbon from Nanoshell-Containing Carbon
Naokatsu Kannari, Yutaka Nakamura, Jun-ichi Ozaki
Gunma University

Mesoporous carbon (MC) is a type of porous carbon material with pore diameters in the range 2–50 nm. MC has attracted much attention because of its potential for use in many applications. In particular, it may be used in electrodes for electric double-layer capacitors or Li-ion batteries, catalysts for some organic synthesis reactions, and supports for biomolecules or metal catalysts.

Nanoshell-containing carbon (NSCC) is one of the nanostructured carbon materials that was identified by Ozaki et al. It is a promising material for a cathode catalyst in the polymer electrolyte fuel cell replacing Pt catalyst. Nanoshell (NS) and amorphous carbon moieties (ACM) are the principal components of NSCC, where NS possesses a hollow spherical shape whose wall is composed of turbostratic layers with diameter of 20 to 50 nm. Typically, a starting polymer such as phenol-formaldehyde resin or furan resin is carbonized in the presence of transition metal complexes such as metallophthalocyanines, resulting in the formation of NSCC. NSCC is expected to contain mesopores because there are mesosize vacancies or interstitial spaces between the NSs. Since the interstitial mesopores in the original NSCC are clogged with ACM, the selective elimination of these moieties produces MC with unique properties. In the present study, we propose a new technique for the sculpture preparation of mesoporous carbon, which eliminates ACM from NSCC by H2O2 oxidation in order to obtain MC.

In this study, untreated NSCC (un-NSCC) is prepared by the carbonization of the mixture of phenol-formaldehyde resin and Co-phthalocyanine. The carbons were then finely pulverized by a planetary ball mill followed by acid washing to remove the metal species resided on the carbon surface. H2O2 treated sample (P1-NSCC) was obtained by treatment of NSCC with 30 % H2O2 at 100°C. P2-NSCC and P5-NSCC were also prepared by the repetitions of the H2O2 treatment, two or five times.

Scanning and transmission electron microscopies revealed that increased repetition number of the H2O2 treatments resulted in the selective elimination of ACM and the increase of NS fraction with crystalline structure. The mesopore volume and mesopore ratio measured by N2 adsorption-desorption measurement remarkable increased by multiple repetitions of the treatment. This was because the H2O2 treatment further developed the mesoscale vacancies, which had been left by the removal of ACM and were located at the interstices of the NS particles. In particular, when the treatment was repeated five times, the highest mesopore ratio (calculated from the ratio of mesopore surface area to BET surface area or the ratio of mesopore volume to total pore volume) of approximately unity was observed.



396
Iron-Catalyzed Formation of Nanoshell-Containing Carbon from Different Types of Polymers and Their Activities for Oxygen Reduction Reaction
Naokatsu Kannari, Katsutoshi Yabutsuka, Takuya Maie, Jun-ichi Ozaki
Gunma University

 Polymer electrolyte fuel cells (PEFC) have been recognized as the most attractive energy-converting devices due to their high efficiency and low or zero emissions. Platinum has been exclusively employed as the catalysts for anode and cathode in PEFC; the cathode, in particular, requires more platinum than the anode, because the cathode reaction i.e. oxygen reduction reaction (ORR) is quite slower. This is recognized as a serious problem preventing the actual utilization of PEFC. Therefore development of non-platinum cathode catalysts for PEFC is one of the most serious issues in the practical application of PEFC

 Nanoshell-containing carbon (NSCC) is prepared by the carbonization of starting polymers in the presence of transition metal complexes. Nanoshell is a type of nanocarbon, whose structure is hollow spherical shape with 20-50 nm by stacking of hexagonal carbon layers. NSCC is a promising candidate for the cathode catalyst in PEFC replacing Pt catalyst because of its high catalytic activity for ORR.

 We tentatively attributed the ORR activity of NSCC to the presences of surface defects such as non-planar structure and edges on the surfaces of nanoshells. In order to prepare more active ORR catalysts than the conventional NSCCs, we need to find ways to introduce such defects more efficiently. The possible ways to introduce such defects are to change the types of precursor polymers that have different carbonization behaviors such as resulting in graphitizing or non-graphitizing carbons, or providing mechanical stresses on the partially carbonized polymers. In the present study, we studied the differences in the nanoshell formation during carbonizations of three different polymers, poly (vinyl chloride) (PVC), novolac-type phenol-formaldehyde resin (PFR) and poly (acrylonitrile) (PAN), in the presence of iron phthalocyanine (FePc) complex as the nanoshell forming catalyst.

 The specimens were prepared by carbonizing the polymers which included FePc at 3 wt %Fe to the polymer at 1000°C for 1 h in a nitrogen stream. The carbons were then finely pulverized by a planetary ball mill followed by acid washing treatment to remove the metal species resided on the carbon surfaces.

 Transmission electron microscopy revealed that all the polymers resulted in the formations of nanoshells; however the crystallinity depended on the types of polymers. PVC-NSCC showed two types of crystalline carbons; i.e. nanoshells and graphitic platelet. PFR-NSCC produced nanoshells whose crystallinity was the same as the ones formed in PVC-NSCC. The nanoshells formed in PAN-NSCC had irregular shapes with wavy graphitic layers, i.e. many defects were introduced. Among the three NSCCs, the ORR activity of PAN-NSCC was the highest. Thermogravimetric measurements revealed a retarded evolution of fragments relating to FePc by ca. 100°C in the case of PAN. The results obtained here clearly indicated that the selection of polymers is a key to prepare more active NSCC for ORR.



398
Influence of Ball Milling of Partially Carbonized Precursor composed of Phenol-formaldehyde Resin and Cobalt phthalocyanine on the Developments of Nanoshell Structure and Oxygen Reduction Activity
Takuya Maie, Tomoyuki Moteki, Naokatsu Kannari, Jun-ichi Ozaki
Gunma University

Polymer electrolyte fuel cells (PEFC) are the most attractive energy-converting devices because of their high efficiency and low or zero emissions. The fuel cells exclusively employ platinum as the catalysts for anode and cathode; the cathode, in particular, requires more platinum than the anode, because the cathode reaction i.e. oxygen reduction reaction (ORR) is too slow. Development of non-platinum cathode catalysts for PEFC is eagerly required in the practical application of PEFC, since the cost problem due to the utilization of platinum prevents the actual implementation of PEFC.

Nanoshell-containing carbon (NSCC) is one of the most expected non-platinum catalysts, which has been developed by our group. It is usually prepared by carbonizing starting polymers in the presences of transition metal phthalocyanines. The material includes two principal constituents, i.e. amorphous carbon moieties (ACM) and nanoshells (NS). NS has characteristic structure, i.e. hollow spherical shape with 20-50 nm, whose wall is composed by stacked graphitic layers.

We tentatively attributed the ORR activity of NSCC to the presences of the surface defects such as non-planar structure and edges on the surfaces of nanoshells. In order to prepare more active ORR catalysts than the conventional NSCCs, we need to find ways to introduce such defects more efficiently. The possible ways to introduce such defects are changing the types of precursor polymers with different carbonization behaviors such as resulting in graphitizing or non-graphitizing carbons, or providing mechanical stresses on the partially carbonized polymers. In the present study, we introduced an additional treatment to the normal carbonization process, i.e. partial carbonization and ball milling, which was supposed to alter the configuration of aromatic rings developed in the partially carbonized precursor, which would lead to the introduction of defects.

 The carbon precursor for NSCC was a mixture of a novolac-type phenolic resin and cobalt phthalocyanine (3 wt% Co). Firstly, the precursor was partially carbonized at 500 deg.C for 1 h, and then it was mechanically treated by using a planetary ball mill operated at an acceleration of 38 G. Finally it was carbonized at 1000 deg.C for 1 h in a nitrogen stream followed by acid washing with hydrochloric acid to remove the resided metal species on the carbon surface, which is referred to as 500-BM-1000-NSCC. A control NSCC was prepared by directly heating the precursor to 1000 deg. C and held it for 1 h, followed by pulverization and acid washing treatments. The ORR activities of the prepared carbons were evaluated by using linear sweep voltammetry in 0.5 M H2SO4 aqueous solution saturated with oxygen.

 Both 1000-NSCC and 500-BM-1000-NSCC were found to form NSs; however the latter showed lower crystallinity of the NS walls, indicating a hindering effect of the additional treatments on the development of crystallinity of NS particles. As expected, the ORR activity of 500-BM-1000-NSCC was higher than that of 1000-NSCC. The results obtained here clearly indicated the importance of the additional treatments for preparing more active NSCC for ORR.



399
Aqueous dye adsorption on ordered mesoporous carbons modified with lanthanum
Joanna Goscianska, Michał Marciniak, Robert Pietrzak
Faculty of Chemistry, Adam Mickiewicz University in Poznań

The discharge of dye wastewater from industry has become one of the most serious pollutants in water. Various treatments for removal dyes have been reported, such as adsorption, photodegradation, biodegradation. Among these techniques, adsorption on carbon materials is one of the most efficient and frequent methods on removal dyes and decoloration. The previous researches showed that micropores were dominant in common activated carbons, so that bulky molecules or macromolecules cannot easily penetrate into the micropores and adsorb onto them. Therefore, the performance of common activated carbons in bulky molecules adsorption is rather constrained due to the microporous nature of activated carbons. Mesoporous (2–50 nm) carbons which have ordered pore structure, high surface area and large pore size provide marked advantages in bulky dye molecules adsorption [1-3].

The subject of the research work reported was to synthesize the series of mesoporous carbons (from various silica templates, e.g. SBA-15, KIT-6) as supports for lanthanum. Incipient wetness technique was used to impregnate all the carbonaceous supports with an aqueous solution of lanthanum chloride in the amount necessary to obtain 0.5, 1, 3, 5 wt. % La loading. The prepared materials were characterised by the means of nitrogen adsorption/desorption measurements, as well as X-ray diffraction, FT-IR spectroscopy, scanning and transmision electron microscopy. The content of the surface oxygen functional groups, both acidic and basic, was determined according to Boehm method. Finally, we will correlate the surface properties with ability of mesoporous carbons impregnated with lanthanum chloride to remove dyes such as methylene blue, tartrazine and methylene orange.

The results have shown that lanthanum strongly determine textural properties of the mesoporous carbons. The impregnation of the carbonaceous supports with lanthanum chloride leads to decrease in their surface area and pore volume. Small angle XRD patterns and TEM images confirmed the ordered mesoporous structures of materials obtained. All the mesoporous carbons modified with lanthanum show the well adsorption capacity towards methylene blue, tartrazine and methylene orange. After investigating the adsorption isotherms of these dyes, they all fit the typical Langmuir adsorption model. The adsorption amount is mainly affected by BET surface area and the structure/size matching between adsorbent and adsorbate.

References

1. Y. Dong, H. Lin, F. Qu, Synthesis of ferromagnetic ordered mesoporous carbons for bulky dye molecules adsorption, Chemical Engineering Journal 193–194 (2012) 169–177.

2. A. Derylo-Marczewska, A.W. Marczewski, Sz. Winter, D. Sternik, Studies of adsorption equilibria and kinetics in the systems: Aqueous solution of dyes–mesoporous carbons, Applied Surface Science 256 (2010) 5164-5170.

3. X. Dong, J. Fu, X. Xiong, Ch. Chen, Preparation of hydrophilic mesoporous carbon and its application in dye adsorption, Materials Letters 65 (2011) 2486-2488.



400
Annealing effect on nanographite
Naira Balzarettia,*, Jackeline Britob, João Alziro Jornadac, Antonio Villanuevad
a IF-UFRGS
b PGCIMAT-UFRGS
c INMETRO
d Peru

Recently we have shown that it was possible to produce nanographite samples through the pyrolysis under high pressure of methyl groups coating nanosize grains of amorphous silica (hydrophobic aerosil) in the temperature range from 1000°C to 1600°C [1]. The atomically dispersed carbon content of the aerosil was from 0.7 to 4 wt %. The effect of high pressure was to inhibit the diffusion of carbon atoms during the pyrolysis under high temperature. In fact, Raman spectroscopy and transmission electron microscopy analyses revealed the formation of graphite nanosheets from 5 to 35 nm size. The Raman spectra of these samples showed an unusual intense and narrow D band, with a very large ID/IG ratio, close to 7, corroborating the formation of very small graphite domains in the boundaries in-between the silica grains when the pyrolysis was performed at 1.25 and 2.5 GPa. The silica matrix could be removed by chemical etching to release the carbon nanostructures. The aim of the present work was to investigate the thermal stability of these nanographite structures under high temperatures. It was observed that the Raman spectrum remained practically the same after annealing up to 600°C under argon atmosphere. The annealing at higher temperatures, however, indicated the formation of amorphous carbon due to the enlargement of the D and G peaks. This effect may be a consequence of the unstable thermodynamic situation of the dangling bonds at the surface of the nanographite sheets produced under high pressure. When the annealing temperature was high enough to promote carbon diffusion, the minimization of energy would induce the formation of larger graphitic structures. In fact, when the annealing was performed within the silica matrix, it was observed by transmission electron microcopy the enlargement and increasing curvature of the carbon nanostructures after annealing above 600°C. On the other hand, when the annealing was performed after removing the silica matrix it was observed that, above 900°C, the carbon nanosctructures probably volatized.

[1] A.E.L.Villanueva, N.M. Balzaretti, J.A.H. Jornada, J. Raman Spectrosc. 2012, 43, 1029-1034.



402
Confined nanoalloys in ordered porous carbon by a one-step synthesis pathway and their interactions with hydrogen
Camelia Matei Ghimbeua,*, Claudia Zloteab, Jean-Marc Le Meinsa, Michel Latrocheb, Cathie Vix-Guterla
a Institut de Science des Matériaux de Mulhouse, UMR CNRS-UHA, Mulhouse, France
b Institut de Chimie et des Matériaux Paris-Est, CNRS-UPEC, UMR 7182, Thiais, France

The synthesis of hybrid carbon materials with well-defined and controllable properties at the nanometer scale remains still a challenge. The general approach used for their synthesis consists in the preparation of an ordered carbon material by a hard-template method followed by impregnation with a metal salt and reduction. Very small and well-dispersed particles (2-10 nm) in the porous carbon network can be obtained by this way [1-2]. We could highlight that such combination between a nanostructured carbon and very small metal particles allow to prevent their coalescence and furthermore improve the hydrogen sorption, kinetics and thermodynamics properties [3-4] compared to porous carbons. However, this multi-step hard template synthesis approach is rather time-consuming and expensive. Hence, in the present work, we report on the synthesis of nanosized transition metals and metal alloys (Pd, Ti, Ni, Co, Fe) in ordered nanostructured carbon materials by a simple one-step pathway. This involves the self-assembly of carbon precursors in the presence of a structural directing agent and the metal salt. To our knowledge, this is the first time that carbon-based hybrid materials are prepared by this way using environmental friendly precursors, such as phloroglucinol and glyoxal. This represents a real progress compared to conventionnal carbon precursor such as phenol-formaldehyde known to be cancerogens. Several synthesis parameters (metal precursor type, ratio between the components, temperature…) were tunned and the experimental results (based on TEM, XRD and SAXS measurements) underline that these parameters play an important role on the size and dispersion of the nanoparticles and on the carbon nanostructure. Particulary, TEM tomographies showed that the nanoparticles are embedded in the carbon and that they can grow into the mesopore channels and their walls. The hydrogen storage properties and hydrogen interactions of these hybrid materials were studied. The use of nanoalloys may enhance the hydrogen capacity, due to the synergistic effects and diversity of compositions and structures.

[1] C. Matei Ghimbeu, C. Zlotea, R. Gadiou, F .Cuevas, E. Leroy, M. Latroche, C. Vix-Guterl, Understanding the mechanism of hydrogen uptake at low pressure in carbon/palladium nanostructured composites, J. Mater. Chem. 21 (2011) 17765

[2] P. Dibandjo, C. Zlotea, R. Gadiou, C. Matei Ghimbeu, F. Cuevas, M. Latroche, E. Leroy, C. Vix-Guterl, Hydrogen storage in hybrid nanostructured carbon/palladium materials: influence of particle size and surface chemistry, Int. J. Hydrogen Energy 38 (2013) 952

[3] C. Zlotea, F. Cuevas, J. Andrieux, C. Matei Ghimbeu, E. Leroy, E. Léonel, S. Sengmany, C. Vix-Guterl, R. Gadiou, T. Martens, M. Latroche, Tunable synthesis of (Mg-Ni)-based hydrides nanoconfined in templated carbon studied by in situ synchrotron diffraction, Nano Energy(2013) 2, 12–20

[4] C. Zlotea, M. Latroche, Role of nanoconfinement on hydrogen sorption properties of metal nanoparticles hybrids, Colloids Surf. A (2012), In press, doi:10.1016/j.colsurfa.2012.1011.1043



403
Graphting of activated carbon cloths for selective adsorption purposes
Sandrine DELPEUX-OULDRIANEa,*, Mickael GINEYSa, Ann LAHEAARb, Roland BENOITa, Christine VAUTRIN-ULa, et al.
a CRMD, CNRS-Université, 1B rue de la Férollerie, 45071 Orléans, Cedex02, France
b Institute of Chemistry, University of Tartu, Ravila 14a, 50411 Tartu, Estonia

Due to their developed and accessible porous network, the efficiency of activated carbons (ACs) for adsorption applications is already well established, especially for tertiary water treatments, and particularly at low pollutant concentration. ACs indeed appear as the most competing adsorbents with complete adsorption levels and without generating noxious by-products. Among these, activated carbon cloths (ACC) are interesting candidates as they show minimal diffusion limitation and consequently high adsorption rates.

Beside the porous texture, the surface functionality plays a great role in the adsorption mechanisms, which have still to be better understood. Since the traditional oxidation methods do not allow the surface functionalities of ACs to be perfectly tailored, the chemical grafting of selected functions able to give specific interactions with targeted pollutants appears as an attractive research direction. In this sense, the spontaneous grafting of diazonium salts is promising because it enables selected reactive species to be strongly bonded on the AC surface. Additionally, by controlling the experimental conditions, the grafting level can be well monitored, from a very discreet grafting to complete monolayer coverage.

In the present work, selected functions has been covalently attached on microporous activated carbon powder and cloth. The amount of grafted functionalities on AC has been characterized using elemental analysis, chemical titration, XPS and TPD. For electroactive species, cyclic voltammetry has been applied to quantify the surface concentration of loaded functions. TOF-SIMS measurements were also conducted in order to characterize the homogeneity of the covered surface. In order to determine whether the coupling of diazonium salts blocks the accessible surface area of the carbon substrates or not, the nanotextural properties of grafted AC have been studied by gas adsorption (N2, CO2).

The behavior and reactivity of the two activated carbon samples (powder and fibers) towards chemical coupling of diazonium salts presenting different aromatic substituents have been studied and will be discussed. Finally, the modified AC samples were used for the adsorption of targeted micropollutants and emerging contaminants, and the adsorption selectivity has been established.



404
Influence of carbon pore size on the capacitance of Li-ion capacitors using lithium-based electrolytes
Camelia Matei Ghimbeua,*, Céline Decauxb, Mouad Dhabic, Encarnacion Raymundo-Piñerob, Mérièm Anoutic, et al.
a Institut de Science des Matériaux de Mulhouse, UMR CNRS-UHA, Mulhouse, France
b Centre de Recherche sur la Matière Divisée, CNRS-Université, Orléans, France
c Université François-Rabelais, PCM2E (EA6299), Tours, France

Hybrid Li-ion capacitors (LIC) are currently very promising energy storage devices combining both high energy and power densities They consist of two distinct electrodes: a lithium - battery type electrode (graphite, LTO,…) and a supercapacitor type electrode (generally a porous carbon). We recently showed [1,2] the successful design of a LIC hybrid capacitor with graphite and activated carbon as negative and positive electrodes, respectively, and without lithium auxiliary electrode as the graphite electrode is preloaded from the Li-ion based electrolyte. This system is able to provide an energy density four times higher than the classical EDLC devices. In such a capacitor the capacitance of the system is given by the capacitance of the carbon based positive electrode. In this sense, it is well known that the capacitance of a carbon material is strongly dependent on its textural properties: microporous volume, pore size, balance between the mesopores and micropores etc. [3-5]. Hence, in the present work, the influence of the carbon pore size on the capacitance properties was studied for the first time in LiTFSI electrolytes based on different solvents and the results were compared with classical organic electrolytes for EDLCs. A family of activated carbons with controlled textural and surface functionality were synthesized by activation of coconut shells with CO2 by tunning the experimental parameters.

It was found that the carbon optimal pore size is strongly dependent on the solvent used and the applied current density. A charge storage mechanism is proposed to explain these properties.

[1] V. Khomenko, E. Raymundo-Piñero, F. Béguin, High-energy density graphite/AC capacitor in organic electrolyte, J. Power Sources (2008) 643-51.

[2] C. Decaux, G. Lota, E. Raymundo-Piñero, E. Frackowiak, F. Béguin, Electrochemical performance of a hybrid lithium-ion capacitor with graphite anode preloaded from lithium bis(trifluoromethane)sulfonimide-based electrolyte, Electrochim. Acta 86 (2012) 282-286

[3] C. Vix-Guterl, E. Frackowiak, K. Jurewicz, M. Friebe, J. Parmentier, F. Béguin, Electrochemical energy storage in ordered porous carbon materials, Carbon 43 (2005) 1293-1302

[4] E. Raymundo-Piñero, K. Kierzek , J. Machnikowski, F. Béguin, Relationship between the nanoporous texture of activated carbons and their capacitance properties in different electrolytes, Carbon 44 (2006) 2498–2507

[5] J. Chmiola, G. Yushin, Y. Gogotsi, C. Portet, P. Simon, P. L. Taberna, Anomalous increase in carbon

capacitance at pore sizes less than 1 nanometer, Science 313 (2006) 1760-1763



405
Mechanism of fluorination of various porous carbon materials
Camelia Matei Ghimbeua,*, Katia Guérinb, Marc Duboisb, Cathie Vix-Guterla
a Institut de Science des Matériaux de Mulhouse, UMR CNRS-UHA, 15 rue Jean Starcky, Mulhouse, France
b Université Blaise Pascal, Institut de Chimie de Clermont Ferrand (ICCF), UMR UBP CNRS 6296, Aubière, France

In order to understand the fluorination mechanism of a variety of ordered and disordered porous carbons, the influence of the fluorination conditions on the physicochemical characteristics and adsorption properties were studied in this work by several techniques (nitrogen adsorption, TEM, XRD, XPS, IR and Raman spectroscopies, TPD-MS, solid state NMR with 13C and 19F nuclei). It was for the first time that the temperature programmed desorption coupled with mass spectrometry technique was used to determine the surface chemistry of such carbon fluoride materials and the strength of the C-F bonds. Four types of carbons were synthesised: two Carbide-Derived Carbons (CDCs), two ordered carbons (SBA-15 silica and zeolite beta replica). These were compared with an commercial activated carbon. Several experimental fluorination conditions were performed: molecular fluorination with pure gaseous fluorine in static and dynamic conditions and atomic fluorination generated by xenon difluoride decomposition. Thus, these treatments allowed to control the F/C atomic ratio. For all the fluorinated carbons, the fluorination level was correlated with the fluorine reactivity. We showed that the highest fluorination level is achieved in static conditions compared to the dynamic conditions while the lowest reactivity is obtained with the atomic fluorine conditions. For the same fluorination condition, the C-F bonding is strongly dependent on the physical-chemical characteristics of porous carbon. The carbon replicas are very reactive towards fluorination compared to the CDCs and the activated carbon as underlined by the presence of CFx bonds (NMR and TPD-MS measurements). The carbon textural and structural properties and also its surface chemistry are strongly modified by the fluorination conditions. The carbon modification characteristics with the fluorination conditions will be basically discussed in this paper. The present work allows to understand the fluorination of porous carbons and moreover to select the most suitable fluorination conditions in regard of a specific potential application of these fluorinated carbon materials [1, 2].

[1] H. Touhara, F. Okino, Property control of carbon materials by fluorination, Carbon 38 (2000) 241–267

[2] K. Guérin, M. Dubois, A. Houdayer, A. Hamwi, Applicative performances of fluorinated carbons through fluorination routes: A review, Journal of Fluorine Chemistry 134 (2012) 11–17



406
Electrically Conductive Carbon Nanotube-Filled Acrylic Fiber in Multifilament Continuous Tows
Ashley Morris, Matthew Weisenberger, Stephanie Billiter
UK Center for Applied Energy Research

Through the use of a novel heat treatment process, an as-spun, insulating MWCNT/acrylic fiber was made conductive, on the order of 0.5 Ohm-cm. A 10 wt% polyacrylonitrile (PAN)/dimethylacetamide (DMAc), 20 wt% MWCNT/PAN solution was prepared and solution spun utilizing a bench scale spinline at the UK Center for Applied Energy Research to produce continuous 100 filament tow. Due to shear effects and high draw down ratios commonly encountered during fiber spinning, the filaments were insulating as-spun. However, a simple heat treatment to the fiber at 225 C for 3 hours resulted in a lowering of the fiber resistivity from non-measurable to 0.5 Ohm-cm. This novel heat treatment is hypothesized to have reoriented the embedded MWCNTs, which were previously highly aligned due to the shear effects and draw ratios, resulting in a more random/entangled network of MWCNTs, therefore creating a conductive network within the polymer fiber.

This shift from an initially aligned state stems from dimensional shrinkages of the host matrix fiber (-17% longitudinal and -48% radial, with a -17% mass change) during heat treatment. It is likely that a decrease in fiber diameter and an increase in conductivity are related, as dimensional changes from internal void collapse (radial shrinkage) and relaxation of polymer chains (longitudinal shrinkage, 17%; along with a 17% mass loss) enabled the as-spun insulating fibers to become conductive with an average resistivity of 0.612 Ohm-cm. It is hypothesized that the fundamental mechanism for this transition stems from a corresponding internal rearrangement of MWCNTs commensurate with the dimensional changes. Detailed XRD experiments will be provided testing this hypothesis.

Further work was completed to ensure oxidative stabilization of the fibers during heat treatment was not the cause for the increase in conductivity. Thermogravimetric analysis, as well as differential scanning calorimetry proved that no stabilization reaction was occurring during heat treatment, and that the resulting conductive fibers were not cyclized PAN.

This heat treatment discovery has many unique and novel aspects. For example, there is a one way change in fiber resistance. The application of heat to the fiber results in increased conductivity, which may lead to sensor applications. It is also a supple, conductive material, which can withstand being tied in knots. The fiber is also easy to produce, as the fibers are spun on a conventional wet spinning line in multifilament, continuous tow and need only undergo a short heat treatment to become conductive. Finally, the fibers are a lightweight conductive material (1.5 g/cc), which may have application as signal conducting wires to replace heavier, metal conductor wires. In addition, it may well be preferred to stabilize the host acrylic fiber – thus rendering a fire-retardant AND electrically conductive fiber.



411
Porosity and Guest Molecules as a Potential Barrier Moderator in Activated Carbon Fibers
Wojciech Kempińskia,*, Damian Markowskia, Mateusz Kempińskib
a Institute of Molecular Physics PAS, M. Smoluchowskiego17, 60-179 Poznań, Poland
b Faculty of Physics, A. Mickiewicz University, Umultowska 85, Poznań, Poland

The paper is focused on modifications of the ACF electronic properties generated by the guest molecules located inside the pores of ACFs of different porosity. Both parameters, porosity and specific guest molecules, decide about the potential barriers defined by T0 parameter – the energy needed for hopping of charges in the model of charge carriers transport in ACF [1,2].

The problem of ACF as a quantum dots matrix is discussed.

Acknowledgements:

This research was supported by the Polish grant MNiSW DPN/N174/COST/2010 and COST MP0901 “NanoTP”.

[1] M. Kempiński, W. Kempiński, J. Kaszyński, M. Śliwińska-Bartkowiak, „Model of spin localization in activated carbon fibers” Appl. Phys. Lett. 88, 2006, p. 143103–143103,

[2] S. Lijewski, M. Wencka, S. K. Hoffmann, M. Kempiński, W. Kempiński and M. Śliwińska-Bartkowiak “Electron spin relaxation and quantum localization in carbon nanoparticle: Electron spin echo studies” Phys. Rev. B 77, 2008, p. 014304-014304,



412
CHAR DEVOLATILIZATION INDEX FROM COAL BLENDS
Edward Garcíaa,*, Deisy Chavesb, Maria Trujillob, Juan Barrazaa, Francisco Velascoc, et al.
a Escuela de Ingeniería Química, Universidad del Valle
b Escuela de Ingeniería de Sistemas, Universidad del Valle
c Escuela de Ingeniería de Recursos Naturales y Medio Ambiente, Universidad del Valle

Char production plays an important role in combustion, as catalysts in dehydrogenation process and in the production of activated carbon, among others. Char devolatilization index represents a parameter that determines the feasibility to liberate volatile matter from raw coals or coal blends. The aim of this study was to evaluate the effect of coal blend on char devolatilization index. In this study, samples of chars from pure and binary blend coal (50-50 %w/w), located at three regions of Colombia (Antioquia, Cundinamarca and Cauca Valley) were produced in an entrainment tubular reactor under nitrogen atmosphere with an oxygen concentration of 1% v/v. The char samples, with particle size smaller than 200 mesh, were obtained at temperatures 800 and 1000 °C and a residence time of 200 ms. Results showed that both, ash percentage and devolatilization index increase with temperature. Original and coals blends from Antioquia, despite of the highest volatile matter content, showed the lowest devolatilization index whereas Cundinamarca coal, characterized by low amount of volatile matter, produced the highest devolatilization index. Results also showed that for some coal blends occurs synergism, may be due the different original coal characteristics.



415
Petroleum coke activation: thermogravimetric behavior and scale-up effect
Manoel Alvarez Mendeza, Guilherme B.M. Almeidaa, Filipe V. Ferreiraa, Antonio C.L. Lisboab, Aparecido R. Coutinhoa
a Methodist University of Piracicaba - UNIMEP
b State University of Campinas - UNICAMP

Petroleum coke is basically composed of amorphous carbon from the thermal separation of the petroleum. When this material is chemically activated with an oxidizing agent, such as the potassium hydroxide (KOH), presents a high superficial area with elevated values of porosity, which allow these materials to be used as filter element to remove impurities from air and water. The main objective of the present work is to evaluate the themogravimetric behavior of the petroleum coke and how the scale-up affects the activation petroleum coke production by chemical activation with KOH. The methodology used to evaluate the thermogravimetric behavior consists in measure the mass variations of petroleum coke in different thermal conditions and different oxidizing environments. Oxygen, carbon dioxide and water was used as oxidizing gas. Potassium hydroxide, sodium hydroxide and zinc chloride was used as oxidizing agent. The evaluation of the scale-up effect in the process was made by a series of activation with differences only in the mass of petroleum coke used in the process. Analysis of nitrogen adsorption at 77 K, real density by helium pycnometry and thermogravimetric analysis to quantify the volatile and ash content was used to evaluate the scale-up effect. The result indicates that the scale up do not affect almost all the parameters that have been analyzed. The only parameter, which has the impact of the scale up was the thermogravimetric behavior of the activated petroleum coke produced, which is correlated with the deposition of inorganic material on the surface that could not be remove by the process.



416
Preparation and Characterization of Activated Carbonaceous Materials from Natural Fibers
Carla Rombaldoa, Larissa Silvaa, Lucas Andriettaa, Antonio Lisbôab, Aparecido Coutinhoa
a Methodist University of Piracicaba
b State University of Campinas

Brazil is currently the largest producer and exporter of natural fibers in the world, with 58% of the total world production. The largest cultivation takes place in 112 cities in the northeast region of Brazil, in the Bahia state, the Sisaleira region. Natural fibers can be divided according its origin into three categories, vegetable, animal and mineral. The vegetable fibers can be extracted from stems of plants, leaves, fruits and seeds of plants. The jute fiber is the second natural cellulose fiber most common in the world, and has excellent mechanical and chemical properties. It can be extracted by maceration of the jute plant using biological and/or chemical methods. The fiber is mainly composed of cellulose (65 wt%), hemicellulose (22.2 wt%) and lignin (6.8 wt%), besides water soluble fats and greases. The sisal fiber yields about 80 million dollars to Brazil, besides generating more than half a million jobs in its chain of services, demonstrating the crucial socioeconomic role of sisal in these areas. Tanzania and Brazil are the two main producers of sisal fibers in the world. The objective of the present study was the preparation and characterization of activated carbon materials from natural fibers (ACF), using the jute and sisal as raw materials. The preparation was made by physical activation process divided in two stages, beginning by carbonization of the raw material, followed by the activation with an oxidizing gas, such as steam or carbon dioxide. The objective of the carbonization is to eliminate the non-carbonaceous compounds present in the fibers. The carbonization temperature used in the present work was between 200 °C up to 300 °C. In the activation step amorphous carbons produced in the carbonization reacted with the oxidizing gas at temperatures ranging from 700 °C up to 900 °C, releasing the blocked pores and forming new pores, which give a higher adsorptive capacity for the activated natural fibers. Nitrogen gas adsorption at 77 K was used in order to evaluate the influences of the carbonization and activation parameters used to produce the ACF from jute or sisal. The results indicate the possibility to produce a porous material with a microporous or mesoporous structure, depending on the parameters used in the process, resulting in materials with specific surface area in the range of 800 m2.g-1.



420
Graphene / Polyaniline Composite Electrode for Supercapacitors
Huaiyan Liu, Huaihe Song, Xiaohong Chen
State Key Laboratory of Chemical Resource Engineering, Ministry of Education, Beijing University of Chemical Technology, Beijing, 100029, P.R. China

Supercapacitors have attracted great attention as the promising power source in recent years. There are two energy storage mechanisms in supercapacitors: electrical double layer (EDL) capacitance and pseudocapacitance.Today, carbon-based materials, such as graphene, have been applied as EDL capacitor electrode materials. Generally, they have good cycling stability but low capacitance.Conductive polymers, such as polyaniline (PANI), are commonly used as pseudocapacitance electrode materials, having high capacitance value but poor cycling stability. In our study, The Graphene/Polyaniline composites were synthesized via in situ polymerization. Aniline monomer was kept in H2O with N,N-dimethyl formamide (DMF) in order to prevent the agglomeration of grapheme nanosheets and control the structure of composites. The composite exhibits a homogeneous spherical like cauliflowers. The specific capacitance of composite electrode is 324 F/g. After soaking with acid, the composite can reach specific capacitance of 497 F/g at a current density of 0.5A g−1. In addition, the capacitance in the long term charge /discharge cycling test reached 456 F/g at a current density of 5 A g−1, suggesting the potential use in supercapacitors. The reasons could be ascribed to the particular structure of composites , the unique slice layer structure and the holes benefiting to electrolyte infiltrate and the ion transmission.



421
Investigation of negative carbon-electrode to improve the high rate characteristic of hybrid capacitor
Ick Jun Kim, Sunhye Yang, Sung Do Yun, In Sik Choi
Korea Electrotechnology Research Institute

Recently, a substantial improvement in the energy density has been achieved through an asymmetric electrode design of utilizing a lithium-ion intercalating electrode as the negative electrode, instead of one of the activated carbon (AC) electrodes in a commercial electric double layer capacitor (EDLC) ; so-called hybrid capacitor such as lithium-ion capacitor (LIC) or nano hybrid capacitor. In these hybrid capacitor, during charge/discharge, lithium-ion intercalation/deintercalation occurs within the bulk of the negative electrode, whereas, anion adsorption/desorption occurs on the surface of the AC positive electrode. Negative electrodes, in generally, are typically produced with increased density in order to minimize contact resistance of carbons and obtain the volumetric capacity in the electrode. However, C-rate of graphite according to literatures shows rapid reduction in C-rate after approximately 2C. In this study, we have investigated the manufacturing parameters to enhance the rate-capability of negative carbon-electrode by controlling the electrode density.



423
Copper oxide/graphene oxide composite nanosheet used as anode material for lithium-ion batteries
Xiaoting Zhang1, Jisheng Zhou1, Huaihe Song*, Xiaohong Chen, Jingming Li
State Key Laboratory of Chemical Resource Engineering, Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing, 100029, PR China

In this paper, copper oxide nanosheets/graphene composites are prepared using a simple solution approach and subsequent annealing at 300 oC. The morphology and structures of as-prepared CuO/graphene composites are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric and differential scanning calorimetry analysis (TG-DSC), X-ray photoelectron energy spectrum (XPS) and Fourier transform infrared spectroscopy measurements (FTIR). It is found that the CuO nanosheets with the average size of ca.200 nm and average thickness of ca. 6.3 nm are layed homogeneously and anchored closely on the graphene surface. The composite, used as the anode materials, exhibits the excellent electrochemical performance. The first reversible capacity is up to ca. 586 mAhg−1 at 50 mAg−1, and the corresponding coulombic efficiency is about 67.63%. At the higher current densities of 500 and 1000 mAg−1, the reversible capacity can reach 350 and 272 mAhg−1 respectively. The excellent electrochemical performance should be attributed to 2D laminated structure of CuO as well as close connection between graphene and CuO: (1) 2D laminated structure of CuO can withstand more impact from the intercalation/de-intercalation of lithium-ion compared with other structure such as nanoparticles. (2) Both the 2D structures and close connection make the conductive network of graphene and CuO more stable. Therefore, the CuO nanosheets/graphene composite shows the great potential for application in the anode.



424
Synthesis of metal-encapsulated carbon nanotubes and electromagnetic interference shielding behaviors of their composites
Byung-Joo KIMa,*, Kyong-Min BAEb, Young-Sil LEEc, Kay-Hyeok ANa
a Jeonju Institute of Machinery and Carbon Composites
b Department of Chemistry, Inha University
c Cheil Industries Inc

In recent years, electromagnetic interference (EMI) has become a critical problem to electric devices because it causes the malfunction of electric devices, such as the control panels of airplanes, mobile phones and many computers, and has adverse effects on human diseases, such as breast cancer and leukemia. Among the electric devices, the malfunction of an electric control unit (ECU) in automobiles by EMI is considered as a key reason for sudden acceleration. To ensure the safety of driving automobiles, major car makers have been trying to develop high performance and light EMI shielding ECU housing materials.

Encapsulation ferromagnetic metals into carbon nanotubes can be very important due to their good magnetic and electric properties, resulting in the high EMI shielding performance. In this work, we report the synthetic methods for Fe and Co encapsulated carbon nanotubes as functions of reaction temperatures and carbon sources. Me-encapsulated carbon nanotubes have various tube diameters and metal content according to the synthetic conditions. We also report the EMI shielding performance of me-encapsulated carbon nanotube-filled propylene composites.



425
Construction of Graphene-Encapsulated Copper Spheres
Jisheng Zhou, Huaihe Song, Xiaoting Zhang, Jingming Li, Xiaohong Chen
State Key Laboratory of Chemical Resource Engineering, Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing, 100029, PR China

Graphene encapsulated copper spheres (GECSs) can be prepared via the conformational change of graphene activated by annealing the cupric nitrate and graphene. The morphologies and structures of as-prepared GECSs and CGBs were investigated by scanning electron microscopy (SEM), high-angle annular dark-field (HAADF) scanning transmission electron microscopy (STEM) and energy-dispersive X-ray (EDX) elemental mapping, and X-ray diffraction (XRD). It can be seen that the GECSs with the diameter in the range of 0.5-2 μm are coated intensely by graphene on the surface. And, then, crumpled graphene balls (CGBs) can be obtained after removing the copper. The formation mechanism of graphene-encapsulation structures can be attributed to the conformational changes of graphene actived by the melting copper particles, while the driving force for curl of graphene may be attributed to the Van del Waals force and also the capillarity force beween melting metal and graphene. These novel grpahene-based structures are expected to be applied in energy storage, catalyst, etc.



426
Effects of graphene oxide addition on the formation and properties of resorcinol-formaldehyde aerogels
Kang Guo, Huaihe Song, Xiaohong Chen, Xian Du
State Key Laboratory of Chemical Resource Engineering, Key laboratory of Carbon Fiber and Functional Polymers, Ministry of Education, Beijing University of Chemical Technology, Beijing 100029, China

Resorcinol-formaldehyde (RF) carbon aerogels are novel porous carbon materials with many interesting properties, such as low mass densities, continuous porosities, and high electrical conductivity. These properties are derived from the three-dimensional nano-network structure. The great challenge associated with the preparation of RF aerogels comes from the nanopores collapse and shrinkage during drying, and one of the main reasons is the poor mechanical properties of the constituting network. Incorporating with reinforcement additives that have strong interaction with matrix is a widely used technique to improve the mechanical properties of polymer materials. Graphene oxide, due to its remarkable intrinsic properties, is one kind of important reinforcement additives in the design of new composite materials. In this paper, GO/RF composite aerogels were prepared by sol-gel polymerizaion of resorcinol (R) and formaldehyde (F) in aqueous suspensions with different concentrations of GO (0~2 wt%) and dried at ambient pressure. We investigated the influence of GO content on the structure and physical properties of aerogels. It is found that GO can be well-dispersed in RF matrix, and obviously accelerate the gelation of RF solution and reduce the drying shrinkage and density of aerogels.



427
The generation and catalytic oxidation of surface oxygenated complexes on the surface of soot
Xiaodong Wu, Shuang Liu, Duan Weng
Tsinghua University

The removal of soot in diesel exhaust is a topic of ongoing researches due to the environmental and health impacts of these carbon nanoparticles. In the catalytic oxidation of soot, the formation and further oxidation of SOCs (surface oxygenated complexes) are important steps. The sulfated Pt/Al2O3 catalyst exhibits a much higher catalytic activity than Pt/Al2O3 for soot oxidation in a feed flow containing NO and O2. Further studies with FTIR and soot–TPO ascribe its good activity to a synergistic effect between sulfate species and platinum. The NO2 generated from NO oxidation on the Pt active sites can first attack the soot surface, leading to the formation of SOCs. The catalytic oxidation of these surface oxygenated species is accelerated by the addition of sulfates because of the promoted transfer of the adsorbed NOx from the alumina support to soot, which provides more chance for NO2–soot reaction. Thus, the surface sulfate species act as an promoter for the decomposition of the SOCs, resulting in a high efficiency in the catalytic oxidation of soot.



428
Use of different activated carbons in the preparation of porous BaTiO3-based ceramics
Jorge R. B. Tagarro, Miguel A. Schettino Jr., Gustavo R. Gonçalves, Alfredo G. Cunha, Francisco G. Emmerich, et al.
Federal University of Espirito Santo

BaTiO3 ceramic can be used as a dielectric and piezoelectric due to its high dielectric constant and ferroelectric characteristics. Donor-doped BaTiO3 ceramics may present an anomalous increase in their electrical resistivity near the Curie temperature, which is known as positive temperature coefficient of resistivity (PTCR) behavior. Since porous BaTiO3-based ceramics may exhibit larger PTCR characteristics than dense ceramics, in this work we have investigated the use of different activated carbons to produce pure and doped porous BaTiO3-based ceramics, using Nb as donor dopant. We have used a commercial activated carbon and activated carbons from endocarp of babassu coconut. Three methods and some of their combinations were used to prepare the final products: solid-state synthesis; sol-gel synthesis; and ball milling. Among other techniques, the produced materials were characterized with X-ray diffraction, specific surface area, electrical resistivity, electrical polarization, and dielectric constant measurements. Some properties of the developed materials are currently under investigation with the objective of being optimized for possible applications.



429
CHARACTERIZATION OF POROUS GRAPHITE MATERIAL BY USING COMPUTED TOMOGRAPHY AND OPTICAL MICROSCOPY OF A POROUS GRAPHITE MATERIAL
Luiz Pardinia,*, Christian Von Dollingerb
a DCTA/IAE/Materials Division
b DCTA/IAE/Materials Divison

Solid carbon materials are used in many important industrial sectors, ranging from household appliances to nuclear industries. The processes to obtain carbon materials uses heat treatment cycles that can reach up to 2800 oC. Particularly, solid carbons in the form of synthetic graphite are obtained by mixing coke, pitch and other additives, such as carbon black and anthracite, which results in final properties of the materíal suitable for industrial use. The pitch/coke/additives mixture can be processed by extrusion, uniaxial compression or isostatic pressing. Once molded, the “green” graphite material is submitted to controlled heat treatment to convert all organic materials into carbon. Processing details and properties of graphites have been described elsewhere. During heat treatment processing, low molecular weight gas release is the main event that takes place, which results in porosity and microcracks which affects thermal and mechanical properties of the graphite.

The amount of porosity in graphites and other carbon bodies have been made by mercury porosimetry through the years. Mercury porosimetry have many drawbacks related to operational constraints and accuracy of results. In present work, industrial graphite samples having different densities, ranging from 1.75 g/cm3 to 1.35 g/cm3, were characterized by using computed tomography and light optical microscopy. The range of porosity was obtained by controlled oxidation of the pristine graphite material (1.75 g/cm3). X-ray computerized tomography (CT) has been invaluable for medical diagnosis since the early seventies. In recent years, CT has gained attention in the field of nondestructive characterization for materials during processing stages and as an evaluation and quality control tool. Porosity can be calculated from the CT image by scanning the material piece detecting the pore space by image and volume by segmentation techniques. Segmentation is the first treatment applied to CT images before analyzing the physical characterization. It consists of the pores spaces extraction in a given scale corresponding to the CT image resolution. X-ray CT has the ability to show sample cross-sections in a nondestructive way have also made it successful in industry. Results of porosity obtained by X-ray CT and micrographs were compared in order to correlate amount, shape and distribution.



430
ELETRICAL RESISTIVITY AS A TOOL FOR PROCESS MONITORING DURING CARBON FIBER/PHENOLIC COMPOSITE PYROLYSIS
Luiz Pardinia,*, Williane Oliveirab
a DCTA/iAE/Materials Divison
b DCTA/IAE/ASA

Carbon fiber reinforced carbon composites are a class of materials that belongs to the family of thermostructural composites. These materials are essential for high demanding applications such as for structural thermal protection systems used in aerospace components. Inevitably, during the cycles of processing inherent to these materials, temperature cycles are necessary either to convert an organic matrix material, such as pitch or a thermoset resin, to a carbon matrix, or even during densification of a fibrous porous carbon fiber perform, gradually reducing the pore volume fraction of the material. In both cases changes in the morphology e microstructure occurs, as well as in the thermomechanical properties. So, the action of temperature during processing undergoes changes in the spectrum of mechanical, thermal and electrical properties during the steps of processing.

Electrical resistivity has been used as a technique for process monitoring and quality control of many industrial materials, such as graphite manufacturing and SiC manufacturing. For solid homogeneous materials electrical resistivity is a function of electronic charge multiplied by the electron movement e by the electron flux concentration, in the conductor(2). Besides, electrical resistivity can be associated to microstructural characteristics of materials in low and high temperatures. The technique is based on the application of an electrical potential V [volts, J/C] through the body of a material, where a current of magnitude i [amperes, C/s] flows through. In many materials at low voltage values the current if proportional to V, which is described by the Ohm law (i = V/R), where R is the electrical resistance in ohms (W). The electrical resistance depends on the intrinsic electrical resistivity (r) and the geometry of the material, where the current passes through an area of a material (R = rl/A). The objective of this work is to investigate the electrical resistivity changes during processing of a 2D carbon fiber/phenolic resin composite up to 1000 oC, where a polymer matrix composite material is converted to a carbon fiber reinforced carbon material. The measurements of electrical conductivity where conduced by using the ASTM C611 – 1998 standard. Results have showed that a 2D carbon fiber/phenolic resin composite has an electrical resistivity, measured by the four point method, of 0.093 mΩ/m. After heat treatment up to 1000 oC, which converts the polymer matrix to a carbon matrix, the carbon fiber reinforced carbon composite, having 25% pore volume, has an electrical resistivity of 0.060 mΩ/m. This indicates that convertion of a polymer matrix to a carbon matrix plays the role in the electrical resistivity of the material than the formation of pores, that hinders current flow.



431
DFT modeling of H2–gasification promoted by oxygen functionalities
Lucas A. Calderón, Diana López, Juan F. Espinal
Institute of Chemistry, University of Antioquia, A.A. 1226, Medellín, Colombia

When molecular hydrogen reacts with a carbonaceous material to generate methane as a main product, the process is known as H2-gasification. Even though the reaction of H2 and char is thermodynamically favored, its kinetics is not. It has been reported that oxygen functionalities introduced by partial combustion or chemical oxidation before H2-gasification increase the rate of CH4 formation [1]. Due to the complexity of the system and the limitations of available experimental techniques, molecular modeling is a useful tool for increasing our understanding of the reactions that take place at molecular level. In order to model the char structure, molecular systems (with zigzag upper edge configuration) were chosen according to the average size reported for aromatic clusters in this carbonaceous material [2]. To understand the effect of oxygen-groups at a local level, groups such as semiquinone, ether and pyrone have been introduced in several H2-gasification mechanisms. The thermodynamic (ΔH, ΔS and ΔG) and kinetic (k) information for each step and for the whole mechanism was evaluated at the B3LYP/6-311++G** from 300 to 2000 K at 1 atm. Among the main results, the global process is less exergonic when increasing temperature for all the evaluated mechanisms. For the whole mechanism in the zig-zag edge, a reasonable agreement was obtained between the ΔH300 (-58.6 kJ/mol) and the experimental ΔH°298 for CH4 formation (-74.9 kJ/mol). Regarding the effect of oxygen groups, it was found that the presence of the ether and pyrone functionalities thermodynamically and kinetically promote the H2-gasification of the fragments with zig-zag configuration in the whole range of temperature. As for the semiquinone group, its presence on the zigzag edge becomes the H2-gasification less favorable from a thermodynamic point of view.

[1] Treptau, M. H.; Miller, D. J. Carbon 1991, 29, 531.
[2] Perry, S. T.; Hambly, E. M.; Fletcher, T. H.; Solum, M. S.; Pugmire, R. J. Proceedings of the Combustion Institute 2000, 28, 2313.



433
Cobalt nanowires encapsulated in carbon nanotubes produced by methane catalytic decomposition
Beata Michalkiewicz, Justyna Majewska
The West Pomeranian University of Technology in Szczecin

In order to metal filled CNT synthesis several method have been attempted: filling with melted metal due to the capillarity effect, opening by boiling acid followed by an inclusion of metal oxide or metal [1]. One step method are known as well: an arc discharge technique, pyrolysis of metalorganic compounds, but they need high temperature [2].

In this work, we show that the Co/ZSM-5 prepared by impregnation method can be used as catalysts of CNT filled with continuous cobalt nanowires (CoF-CNT) growth from methane decomposition even at the temperature of 400oC and of 800oC. This is the one step method simpler and cheaper than the other described up to now.

The choice of cobalt as the material encapsulated inside carbon nanotubes (CNTs) is motivated by interesting magnetic properties of composite cobalt-carbon nanomaterials [3], which are of great interest for various applications such as magnetic data storage, ferrofluids, or magnetic resonance imaging [4].

The CoF-CNT growth was carried out at atmospheric pressure in a conventional gas-flow system. The morphology of as prepared cobalt nanorods was characterized by TEM and FE-SEM equipped with secondary electron (SE) and backscattered electron (BSE) detectors. Raman and the X-ray diffraction patterns measurements were performed.

The SEM images of catalyst and CoF-CNT obtained at 400 and 800 oC show cobalt nanowires (bright oblong shape). TEM analysis of CoF-CNT obtained at 400 and 800 oC show the presence of cobalt nanorods encapsulated inside the carbon tubes. The carbon produced at 400 oC seems to be amorphous whereas the graphitic lattice of carbon nanotube can be clearly resolved, confirming the multiwalled nature of the carbon nanotube. The interplanar distance for the (002) planes of carbon layers measured from TEM micrographs was equal to 0.34 nm. The average diameter of the CoF-CNT is about 25 and 40 nm for products obtained at 400 oC and at 800 oC respectively. The XRD patterns confirm SEM and TEM observations. On the basis of Raman spectra the relative intensities of the G and D bands, which IG/ID is a measure of the degree of perfection of carbon nanomaterials, were determined. IG/ID was equal to 0.84 for CoF-CNT obtained at 800 oC and 0.69 for obtained at 400 oC ones.

In conclusion, cobalt-filled carbon nanotubes can be produced by simple method. The results of XRD, FE-SEM, TEM indicate that carbon nanotubes filed with cobalt nanowires can be prepared even at 400oC by catalytic decomposition of methane. The results of XRD, TEM, Raman spectroscopy show that at temperature 800 oC better quality of carbon was obtained.

Acknowledgement: The project was financed by the National Science Centre of Poland (N N507 306240)

1. M. Xicheng et al. Mater Let 57 (2003) 2879

2. M. Liu and J. M. Coeley, Carbon 33 (1995) 749

3. M.E. McHenry et al. Phys Rev B 49 (1994) 11358

4. O. Lehtinen et al. Physica E 40 (2008) 2618



441
Fabrication of Hexagonal Cobalt Hydroxide/Graphene Composites Used as anode material for lithium-ion batteries
Jingming Lia,*, Kunhong Liub, Jisheng Zhou*a, Huaihe Song*a, Xiaohong Chena, et al.
a State Key Laboratory of Chemical Resource Engineering, Key Laboratory of Carbon Fiber and Functional Polymers, Ministry of Education,Beijing University of Chemical Technology, Beijing, 100029, PR China
b Petrochemical Research Institute, PetroChina Company Limited, Beijing, 100195, China

A facile precipitation approach is employed to synthesize hexagonal cobalt hydroxide/graphene composites (Co(OH)2/GNS) at room temperature. The morphology and structures of resulting composites are characterized by SEM, TEM, XRD, TG-DSC, XPS and FTIR. Notably, the Co(OH)2 nanoplates, with interesting hexagonal patterns of average size of about 130nm and average thickness of about 40nm, stands vertically rather than lies flat on the surface of graphene sheets. More interestingly, it is confirmed that the Co(OH)2 sheets are single crystalline, and the preferable growth face is (001),which is perpendicular to graphene. Co(OH)2/GNS exhibits not only high specific capacitance, but also outstanding high-rate performance. At current density of 50 mAg−1, the reversible capacity is 976.5 mAhg−1 for the first cycle and remains at 1103 mAhg−1 after 50 cycles without any fads. At 500 and 1000 mAg-1, the reversible capacities can reach up to 590 and 410 mAhg-1, which are 62 and 43 % of that at 50 mAg-1 respectively. We attribute excellent electrochemical performance to the particular structure of Co(OH)2 as well as synergistic effect between Co(OH)2 and graphene. Therefore, transition-metal hydroxide/graphene composites are expected to have potential applications in LIB.



442
Effects of Polyaromatic Compounds on Coke Texture and Strength
TOSHIMASA TAKANOHASHIa,*, NAOTO SAKIMOTOa, YASUYUKI HARADAb, HIDEKAZU FUJIMOTOc
a National Institute of Advanced Industrial Science and Technology
b Mitsubishi Chemical Corporation
c JFE Steel Corporation

Though coal is widely distributed around the world, half of it consists of sub-bituminous coal and lignite, and the amount of caking-coal suitable for coke making is limited. There are two ways to use slightly and non-caking coals. One is to replace coking plants with a new coke-making process, such as the “super coke oven for productivity and environmental enhancement toward the 21st century” (SCOPE21). The second way to use slightly and non-caking coals is to add a caking agent. This method is applicable to existing plants and has a lower initial cost. We have proposed an ash-free coal extract, called “HyperCoal” (HPC), as an additive or alternative for caking coal. HPC can be produced from a wide range of coal types, including slightly and non-caking coals. When HPC was added to a coal blend containing 50% slightly caking coal, the strength of the coke was markedly enhanced. Although the effect of HPC was attributed to its higher fluidity, it was unclear which fraction(s) in HPC was responsible for the enhanced strength and what the mechanism was. Understanding the mechanism may make possible further enhancement of coke strength.

In the current work, polyaromatic hydrocarbons as model compounds of coal extract were added to coal. We investigated the effects of these compounds on coke texture and strength and their mechanism of action.

Addition of large aromatic-ring compounds (coronene, perylene, naphtho[2,3-a]pyrene) greatly enhanced coke strength, whereas three-ring aromatics (anthracene, phenanthrene) had no significant effect on coke strength. In addition, 3 wt% addition of coronene or naphtho[2,3-a]pyrene increased the relative percentage of anisotropic texture at the expense of the isotropic texture. Because large polyaromatic compounds have greater affinity for coal molecules, they co-fused with the coal particles. As a result, formation of large pores during coking was suppressed, leading to increased coke strength. In the current paper, the effects of nitrogen-containing polyaromatic compounds will be also reported.



443
Surface modification of porous alumina membranes with nanodiamonds
Jiri Cervenka
The University of Melbourne

Nanoporous membranes are crucial components in various chemical, biological and medical applications such as sensing, separation, filtration and drug delivery. Inorganic nanoporous membranes have gained significant attention in this area due to their easy fabrication, robustness and biocompatibility. Porous alumina membranes with well-ordered pore structures are very popular because of their low fabrication cost, uniform, tunable pore size and high pore density [1]. Anodic aluminium oxide (AAO) membranes are obtained by using common electrochemical-etching techniques and have a honeycomb-like pore structure with short distance ordering. The pore geometry and morphology can be controlled by the conditions during the anodization processes. However, the use of porous alumina membranes is limited owing to their insufficient biocompatibility and resistance to acidic and alkali environments [2]. Various approaches of surface modification of alumina membranes have been reported in recent years [3], including surface polymerization [4], coating it by gold [5] and diamond like carbon (DLC) [6]. Despite of these efforts, fabrication of highly chemically stable and biocompatible porous alumina membranes is still an open issue.

Here we use plasma-enhanced chemical vapor deposition (PE-CVD) to modify the surface of porous alumina membranes with nanodiamond. Nanodiamond coatings are well known for their inertness and biocompatibility. Our CVD process results in uniform thin nanodiamond coatings on the surface as well as inside of the pore structures of free standing anodic aluminium oxide. Different pore sizes (18 - 150nm) and nanodiamond growth conditions have been studied. Chemical stability of the diamond coated alumina membranes was tested in very strong alkali and acid solutions. In all cases the diamond modified porous alumina membranes showed excellent chemical stability. Our samples have been analysed with Raman spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The mechanism of diamond nucleation and growth inside the alumina pores will be discussed. In addition, we will show results of protein adsorption into the pores of porous alumina with and without diamond surface modification.

[1] P. Stroeve, N. Ileri, Trends in Biotechnology 29, No. 6, 259 (2011).
[2] S. P. Adiga et al., WIREs Nanomedicine and Nanobiotechnology 1, 568 (2009).
[3] A. M. M. Jani et al., Chem. Commun., 3062–3064 (2009).
[4] K. E. La Flamme, et al., Biomaterials 28 2638–2645 (2007).
[5] L. Velleman, J. G. Shapter and D. Losic, J. Membr. Sci., 2009, 328, 121–126.
[6] S. Karan et al., Science 335, 444-447 (2012).



444
Investigation of carbon microstructure of binder-coal interface using SEM-EDS and its relationship with the tensile strength of the composite
Atul Sharma, Naoto Sakimoto, Toshimasa Takanohashi
National Institute of Advanced Industrial Science & Technology, Energy Technology Research Institute, Advanced Fuel Group

In this paper, we report a method to produce high strength cokes from non-caking coals that do not show softening/melting properties by adding a coal derived binder. The strength of the carbon composite/cokes produced by our method is higher than the cokes produced by coking coals. Two types of binders, a coal derived HyperCoal and an oil derived Asphalt pitch were added to Anthracite, a low rank coal Adaro and Mulia lignite and carbonized at 1000 oC for 30 min to produce semi-cokes. The strength of these semi-cokes was higher than the semi-coke produced from Goonyella coal, a standard coking coal under similar conditions. Effect of carbon composition of binder, base coal particle size, and binder-coal mixing ratio were investigated. As the bonding of binder on coal particles surface is expected to be dependent on carbon microstructure, chemical composition and chemical structure of both the binder and coal, we investigated the binder-coal interface by SEM-EDS, and Laser-Raman mapping analysis. The study also reports the first observation of coal-binder interface using SEM at microscopic level and correlated with it coke strength. CO2 gasification reactivity at 1100 oC was about 5 times higher than the standard coke.



447
Sonication and oxidation of activated carbon and effect on the removal of Ibuprofen
Hanen Guedidia, Laurent Duclauxa,*, Reinert Reinerta, Jean-Marc Levêquea, Yasushi Sonedab, et al.
a Laboratoire de Chimie Moléculaire et Environnement, University of Savoie, 73376, Le Bourget du Lac Cedex, France
b National Institute of Advanced Industrial Science and Technology, Energy Technology Research Institute, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan

The aim of our work was to study the effect of modification of activated carbon surface by sonication in different solvents on the adsorption properties of Ibuprofen (IB). A raw granular activated carbon (AC) was modified by ultrasonic irradiation at 500 kHz (in a cup-horn reactor) or 20 kHz (probe in a cylindrical reactor) of 5 weight % suspensions in different solvents : H2O2 (35%) or pure water or formic acid (3M) for 5h at room temperature, and concentrated formic acid (98 %) for 2h T=20°C or 65°C . The same carbon was also treated by stirring in H2O2 (35%) solutions. The raw and the modified materials were characterized by N2 adsorption-desorption at 77 K, CO2 adsorption at 273 K elemental analysis, pHPZC (point of zero charge) measurements, laser granulometry, X-ray Photoelectron Spectroscopy (XPS), and infra-red spectroscopy. IB adsorption of isotherms were studied at pH=3. The adsorption properties were correlated to the porous textures, the surface chemistry and the pH conditions.

The ultrasonic treatment at 20 kHz induced a significant particle size reduction due to the cavitation phenomenon. Samples sonicated at 20 kHz in H2O2 were formed of submicrometric particles (d50 ~ 1µm instead of ~ 700µm for AC). Sonication at 500 Kz or impregnation without ultrasound in the same H2O2 solution preserved the micrometric particles (d50 ~ 100µm). The nitrogen adsorption–desorption isotherms for the raw and modified carbons were typical of microporous-mesoporous adsorbent, except that the ultramicroporous volume was slightly reduced for the more oxidized samples.

XPS studies has brought out that the effect of the ultrasonication at 20 Kz or 500 Kz is an oxidation for all the samples except the ones treated at 500 kHz in water and at 20 kHz in concentrated formic acid. The oxidation in H2O2 medium is mainly attributed to the oxidant power of this chemical agent. Ultrasonication at 20 KHz leads to the C-C bond breaking of aromatic planes through cavitation, and further oxidation at the edge of the layers by reaction with water or OH° radicals or gas emitted during the decomposition of solvent (for example formic acid). The sonication in concentrated formic acid might hinder the oxidation due to the higher yied of H2 emission (and also CO2) from the decomposition of HCOOH. Sonolysis of water at 500 kHz is known to produce small amount of H2 (from H° radicals) and H2O2 (from OH° radicals) compared to the sonolysis of formic acid (also giving CO2 and CO emission) which can induce higher oxidation of AC.

The oxidation of the surface of AC has yielded to higher uptake for the IB adsorption, as some oxygenated surface functionalities promote the adsorption of IB [1]. The study of the Pore Size Distributions of IB-loaded and pristine ACs brought out that this molecule was mainly adsorbed in the ultramicropores in agreement with its dimension.

[1] H. Guedidi, L. Reinert, J-M. Lévêque, Y. Soneda, N. Bellakhal, L. Duclaux, Carbon in press 2013 http://dx.doi.org/10.1016/j.carbon.2012.11.059



448
Adsorption of micropollutants onto activated carbon fabric and felt
Sylvain Masson, Laurence Reinert, Sylvie Guittonneau, Laurent Duclaux
Laboratoire de Chimie Moléculaire et Environnement, University of Savoie, 73376, Le Bourget du Lac Cedex, France

The aim of this work is to better understand the adsorption mechanism of micropollutants onto activated carbon fabrics and felts (ACs). Some widespread pharmaceutical molecules: Carbamazepine, Diclofenac, Ibuprofen, Ofloxacin and an endocrine disrupting compound : Bisphenol A were studied as model molecules. The adsorption of Caffeine was also studied as this molecule is usually used as indicator of waste water contamination.

The adsorbents (KIP1200 fabric and CSV4 felt purchased from Dacarb, France) were characterized by N2 adsorption-desorption at 77 K, and CO2 adsorption 273 K, acido-basic titrations (Boehm method), pHPZC (point of zero charge) measurements and by infra-red spectroscopy. The adsorption kinetics and isotherms were studied at pH=7.4 in a NaHPO4/KH2PO4 buffered solution (about 0.04 M) using HPLC for the analysis of organic molecules remaining in solution. The adsorption isotherms of the molecules were studied at 25, 40 and 55°C; and the thermodynamic parameters (isosteric enthalpies and entropies, and Gibbs free energies) were determined. The pore size distributions (PSD) of the loaded carbons were determined by DFT method from gas adsorption isotherms, to investigate the porosity accessible to the adsorbate.

The activated carbon materials were found to be microporous and mainly ultramicroporous and contained low amounts of oxygenated surface groups. The pHPZC of the carbon surfaces were found to be slightly basic (8.75 for the fabric and 7.85 for the felt), indicating positive surfaces at the studied pH.

The adsorption properties were correlated to the porous textures, the surface chemistry and the molecule size, charges and hydrophobicity. The kinetics of all the pollutants, studied at C0=100 ppm, were better reproduced using diffusion model for short time (t<400 min) and by pseudo second model order for longer times. Adsorption saturation was found longer for the larger size molecule (i.e. Ofloxacin, saturation reached after 10 days) in agreement with its hindered diffusion into the micropores. The comparison of loaded volume and accessible volume and the PSD of the loaded and pristine ACs brought out that the smaller molecules (Carbamazepine, Ibupofen, Diclofenac) were mainly adsorbed in the ultramicropores in agreement with their dimensions, whereas the larger molecules (Ofloxacin and Bisphenol A) were also adsorbed in supermicropores.

The adsorption isotherms were better simulated by Langmuir-Freundlich models whatever the micropollutant. The profile of the Carbamazepine adsorption isotherms presented a stronger knee, indicating a higher interaction with the surface than other molecules despite of its positive charge promoting repulsion. This might be due to the higher amount of unsaturated electrons in this molecule. The adsorption isotherms of Carbamazepine were found to be very similar in the buffered solution and in water, showing the absence of co-adsorption of the buffer ions. The thermodynamic parameters of adsorption were interpreted as a function of interactions of the molecules with solvent and carbon materials.

Saturated ACs were then used to study microwave desorption of the pollutants. The experiment was performed in aqueous condition and at low temperature (from 80°C to 180°C) to minimize the degradation of the micropollutants.



450
Adsorption of ibuprofen on modified activated carbon fabrics
Hanen Guedidia, Laurent Duclauxa,*, Laurence Reinerta, Jean-Marc Levêquea, Yasushi Sonedab, et al.
a Laboratoire de Chimie Moléculaire et Environnement, University of Savoie, 73376, Le Bourget du Lac Cedex, France
b National Institute of Advanced Industrial Science and Technology, Energy Technology Research Institute, 16-1 Onogawa, Tsukuba, Ibaraki 305-8569, Japan

This study aims at investigating the performance of fabric activated carbon (FAC) in removing of a widespread drug: ibuprofen. The fabric activated carbon (900-20 from Kuraray, Japan) was used as received and was oxidized by a sodium hypochlorite solution at 0.13 M and by impregnation in H2O2 solution (35%). Besides, the thermal treatment of the FAC in a flow of N2 gas was carried out at 700°C for 1 hour. The raw and modified FACs were characterized by N2 adsorption-desorption measurement at 77 K, CO2 adsorption at 273 K, Boehm titrations, pHpzc (point of zero charge) measurement, X-ray Photoelectron Spectroscopy, and infra-red spectroscopy.

The treatment of FAC by NaOCl decreased both the specific surface area and the micropore volume and increased the acidic functional groups compared to the pristine FAC.

XPS and Boehm titrations results showed that carboxyl and phenol groups were the most abundant oxygen functional groups. However, the treatment of FAC at 700°C under N2, induced a slight increase of the BET specific surface area (1946 vs 1910 m2.g-1) and removed the acidic oxygenated surface groups except the carbonyl groups amount which increased after such treatment.

Ibuprofen adsorption studies of kinetics and isotherms were carried out at pH = 3 and 7 on raw and modified materials. The adsorption properties were correlated to the FAC porous textures, surface chemistry and pH conditions. The thermal treatment of FAC under N2 led to about the same adsorption capacity as the raw FAC at pH 3, as the carbon became slightly oxidized after ageing. However, oxidation by NaOCl induced a decrease in the ibuprofen adsorption explained by the formation of phenolic groups and a decrease of carbonyl groups amount. The isotherms of adsorption were better reproduced by Langmuir-Freundlich models. The adsorption kinetics have been investigated and the results indicated that the adsorption process followed the pseudo-second-order kinetic model. The effect of temperature on the Ibuprofen uptake by the adsorbent was also investigated at three different temperatures (25, 40 and 55°C). The adsorption of ibuprofen was found to be an endothermic process. The pore size distributions (PSD) of all the studied fabric activated carbons loaded with ibuprofen were determined by DFT method to investigate the accessible porosity of the adsorbent molecule. The study of the PSDs of ibuprofen loaded and raw FAC brought out that this molecule was mainly adsorbed in the ultramicropores. However, after the modification either by NaOCl or by the thermal treatment under N2, the ibuprofen was found to be also adsorbed in the supermicropores.



453
Synthesis and study of thermal behavior of nanostructured iron oxides dispersed in carbon materials.
Gustavo Gonçalvesa,*, Miguel Schettino Jr.a, Milton Morigakib, Evaristo Nunesa, Jair Freitasa, et al.
a Laboratory of Carbon and Ceramic Materials, Department of Physics, Federal University of Espírito Santo, Av. Fernando Ferrari, 514, Vitória, 29075-910, Brazil
b Department of Chemistry, Federal University of Espírito Santo, Av. Fernando Ferrari, 514, Vitória, 29075-910, Brazil

Nanostructured iron oxides dispersed in porous materials find a large number of applications in catalysis, magnetic separation and water cleaning, among others. Wet chemical methods have been extensively used for preparation of these materials, allowing the synthesis of products with varied chemical and physical properties. This work describes the synthesis of nanocomposites consisting of iron oxides dispersed into a char and the study of the thermal transformations occurring in these materials as a consequence of heat-treatments. The materials were prepared starting from hydrated iron nitrate, which was mixed with a char (derived from the endocarp of babassu coconut by carbonization at 700 °C) in the presence of ammonium hydroxide in aqueous suspension. The mixture was continuously stirred at room temperature for 1 h, leading to the precipitation of hydrated iron oxide nanoparticles dispersed in the char; next, the powders were separated by filtering and dried at 110 °C. X-ray diffraction experiments performed using synchrotron radiation showed that the as-prepared material was composed of amorphous iron oxides. Scanning electron microscopy (SEM) images combined with energy-dispersive X-ray spectrometry (EDS) indicated a homogeneous dispersion of iron oxides and of silica particles (naturally present in the babassu coconut) throughout the char. The 57Fe Mössbauer spectrum recorded at room temperature for this material exhibited a doublet typical of superparamagnetic particles, with isomer shift associated with Fe3+ oxides. At low temperature (4.2 K) the development of a sextet was evidenced, with a hyperfine magnetic field value consistent with the presence of hematite (α-Fe2O3). In spite of the large iron content in this composite (~39 wt. %) the specific surface area was still relatively high (240 m2/g) as compared to the value corresponding to the babassu coconut char (340 m2/g). Thermogravimetry (TG) and differential scanning calorimetry (DSC) curves recorded under N2 flow showed the release of water at temperatures below 200 °C. Exothermic peaks were detected in the DSC curve at 275 °C (weak) and 425 °C (strong) with negligible weight change, pointing to the occurrence of crystallization processes. Accordingly, X-ray diffractograms recorded in situ during heating showed the presence of broad diffraction maxima associated with the formation of small hematite crystallites (average size ~22 nm) starting from ~250 °C. Further heating caused a progressive growth of the hematite crystallites up to ~530 °C, when the conversion to magnetite (Fe3O4) started to take place. At higher temperatures, wüstite (Fe1-xO) was detected as an intermediate phase (between 780 and 930 °C), and austenitic iron (γ-Fe) became the dominant phase at temperatures above 900 °C. A steep weight loss was observed in the TG curve accompanying this last reduction stage. Upon cooling, γ-Fe was converted into α-Fe (ferrite), which was the dominant phase at room temperature. The final product after heat-treatment at 1000 °C and cooling down to room temperature was a mixture of a silica-rich carbonaceous material with α-Fe crystals (average size ~190 nm) and with minor contributions from wüstite and γ-Fe – this last phase being probably stabilized at room temperature by the inclusion of carbon atoms.



454
Study by X-ray diffraction and solid state 27Al NMR of the thermal changes occurring in alumina-carbon composites.
Thierry Lopes, Gustavo Gonçalves, Ewerton Barcellos Jr., Miguel Schettino Jr., Jair Freitas, et al.
Laboratory of Carbon and Ceramic Materials, Department of Physics, Federal University of Espírito Santo, Av. Fernando Ferrari, 514, Vitória, 29075-910, Brazil

Porous carbon materials containing dispersed aluminum oxides are of interest for many applications, including the removal of fluoride from water and the adsorption of ammonia from gaseous mixtures. Moreover, alumina-carbon composites can also be used to support metallic catalysts, combining the positive aspects of both alumina and carbon as porous supports. In this work we have investigated the structural and chemical transformations occurring in alumina-carbon composites upon heat-treatment, by using a combination of X-ray diffraction (XRD) and solid-state 27Al nuclear magnetic resonance (NMR) spectroscopy. Two different carbon precursors were employed: a commercial activated carbon (denoted as AC) and a char obtained by carbonization of the endocarp of babassu coconut at 700 ºC (denoted as BC), with specific surface areas of 1300 and 340 m2/g, respectively. The alumina-carbon composites were prepared by aqueous impregnation of AC or BC with aluminum nitrate (samples named AC_Al or BC_Al, respectively), using ammonium hydroxide as the precipitating agent. After filtering and drying, the as-prepared powders were heat-treated under argon flow at temperatures up to 1500 ºC. The aluminum compounds present in the as-synthesized AC_Al samples were identified by XRD and solid-state 27Al NMR as nanocrystalline aluminum oxyhydroxides or hydroxides, depending on the detailed synthesis conditions. On the other hand, all aluminum-containing phases were X-ray amorphous in the as-synthesized BC_Al samples, with the presence of a distribution of AlO6 (octahedral Al site), AlO5 and AlO4 (tetrahedral Al site) units revealed by solid-state 27Al NMR spectroscopy. In the case of the AC_Al samples, heat treatment at 400 ºC caused the thermal degradation of the hydroxides and oxyhydroxides and the development of X-ray amorphous or nanocrystalline transition aluminas. The contribution from AlO4 sites was found first to increase with the rise in the heat-treatment temperature, going through a maximum around 800 ºC and then decreasing with the formation of the thermally stable corundum (α-Al2O3) phase, which was fully developed at 1500 ºC. As for the BC_Al samples, no crystalline phase was detected up to 1000 ºC. With increase in the heat-treatment temperature, a small and progressive reduction in the relative intensity associated with AlO5 units was observed in the 27Al NMR spectra of these samples. These results showed that the nature of the carbon material used as support was of great relevance for the definition of the type and crystallinity of the alumina phases formed after heat treatments. Depending on the type of support and on the heat-treatment temperature, alumina-carbon composites containing either nanocrystalline or amorphous alumina phases were produced. Solid-state 27Al NMR was then essential for the characterization of the short-range order occurring in the aluminum-containing phases present in the studied composites.



455
Connection between magnetism and structural distortions in graphene containing vacancies as revealed by ab initio calculations.
Wendel Paz, Wanderlã Scopel, Jair Freitas
Department of Physics, Federal University of Espírito Santo, Av. Fernando Ferrari, 514, Vitória, 29075-910, Brazil.

The consequences of the presence of defects (such as atomic vacancies, edge sites and chemisorbed species) on the peculiar electronic structure of graphene have been intensively investigated in the last years. In particular, it has been shown that the emergence of magnetic features in graphene and other nanocarbons can be associated with the occurrence of some these defects and that the details of the electronic structure are strongly dependent on the type and concentration of defects. In this work, we have used first-principle calculations to investigate the properties of graphene containing carbon vacancies, by using spin-polarized density functional theory (DFT), as implemented in the VASP code. We have studied the formation energy, electronic, magnetic and structural properties of a graphene sheet containing one or more vacancies created by removing carbon atoms from the graphene structure. Different vacancy configurations were investigated, including isolated or interacting single vacancies and divacancies. In all cases, a structural distortion was found to occur in the relaxed structure containing the vacancies. In the case of the graphene sheet containing a single vacancy, the results have shown that a local distortion is formed around the vacancy, with reconstruction of two atomic bonds and with a dangling bond remaining at the third atom adjacent to the vacancy. A systematic investigation of the possible out-of-plane displacement of this third atom was then carried out, in order to ascertain its effects on the magnetic features of the system. The ground state was definitely found to be magnetic and planar, with spin-resolved sigma and pi bands contributing to the total magnetic moment, which was found to be in the range 1.1-1.2 μB per vacancy, depending on the vacancy concentration. However, it was also found that metastable solutions can be achieved if an initial shift of the third atom above a minimum threshold from the graphene plane is provided, which leads to a non-planar geometry and a non-magnetic state. Similar calculations were performed for a graphene sheet containing a divacancy, i.e., with removal of two adjacent carbon atoms; the results showed that the total magnetization is zero, pointing to a non-magnetic ground state for this system.



459
Spatially resolved EELS study of BN/C multilayers films
Nathalie Bruna, Ricardo Torresb, Ignacio Carettic, Ignacio Jimenezc, Virginie Serinb,*, et al.
a Laboratoire de physique des Solides, Bat 510, Université Paris Sud, Orsay France
b CEMES- CNRS, 29 rue J. Marvig, 31055 Toulouse Cédex, France
c Instituto de Ciencia de Materiales de Madrid. c/ Sor Juana Inés de la Cruz, 3, Cantoblanco, 28049 Madrid, Spain

B-C-N coatings exhibit a variety of physical properties that depend both on the B-C-N composition and on the atomic bonding structure. Among these properties are the high hardness and abrasion resistance. Multilayer nanostructuration increases the interface contribution with respect to the total volume and thus enhances mechanical properties of the system[1].

Such multilayers have been deposited by ion beam assisted deposition (IBAD), by using two independent evaporators as sources of C and B atoms, and a Kauffman ion gun as the source of nitrogen ions that impinge the substrate at an angle of 50°. In this study, we have considered a sample with a nominal period of 10 nm, corresponding to the sequence/C/BN/.

Owing to the characteristic nanoscale of the samples, EELS (Electron Energy Loss Spectroscopy) conducted in a STEM (Scanning Transmission Electron Microscope, probe size 0.1 nm) is well suited to their characterization [2]. Indeed this technique can provide both compositional information as well as local bonding from the study of fine structure of the ionisation edges of light elements (B, C, N). In particular we aim to detect and characterize the presence of an interface compound. Spectra acquired by the technique of spectrum-images are analysed by new spectral unmixing algorithms in order to extract base spectra representative of the different phases present [3].

It was observed, for the sample under consideration, a shift of the order of 1 nm between the maximum of the concentration profile of N and the maximum for B. The origin of this shift is not clear. It could result from the experimental process and the action of the N ion gun, or from the preferential affinity between C and N. Anyway this shift seems to hinder formation of the compound BCN. Thus the stacking appears to be rather like C/B(C)N/BC(N) with a mixture of different phases.

BCxN compounds having the best tribo-mechanical properties, optimizing the formation of a layer of this compound would allow better control of the tribo-mechanical properties of the multi-layer.

[1] I. Jimenez, R. Torres, I. Caretti, R. Gago and J. M. Albella, "A review of monolithic and multilayer coatings within the boron-carbon-nitrogen system by ion-beam-assisted deposition", J. Mater. Res., Vol. 27, 05, 2012, pp 743-764.

[2] Colliex C., Brun N., Gloter A., Imhoff D., Kociak M., March K., Mory C., Stéphan O., Tencé M. and Walls M., "Multi-dimensional and multi-signal approaches in scanning transmission electron microscopes", Phil. Trans. R. Soc. A 367: 3845-3858 AUG 2009

[3] Dobigeon N., Brun N., "Blind Linear unmixing of EELS spectrum-images", Ultramicroscopy 120 : 25-34 JUN 2012



461
The Effect of Boron-doping on Electric Conduction Property of Metallicity-Separated Carbon Nanotube-Sheet
Kazunori Fujisawaa,*, Yong Il Kob, Takuya Hayashib, Yoong Ahm Kimb, Morinobu Endob
a Shinshu University, Research Fellow of the Japan Society for the Promotion of Science (PD)
b Shinshu University

Carbon Nanotubes have 1D cylindrical structure which constructed by only sp2 configulation of carbon atoms. Because of sp2 bonding nature, CNTs are considered as a promising material for multi-functional filler and transparent electrode. However, CNTs don’t form 3 dimensional crystal, thus the electron conduction mechanism is not simple. The electronic structure of isolated CNT is determined by rolling up way of graphene-sheet (Chirality), and varies from semiconductive to metallic. In addition, macroscopic factors (percolation and orientation etc.) affect the electron conduction mechanism as well as microscopic structure, thus the analysis of both of macro- and micro-scopic structure is quite important.

Boron doping is widely used to increase the conductivity of carbon material. Under high temperature environment, the boron atom easily diffuse into carbon lattice as substitution of carbon atom, thus boron atom is doped into carbon structure with minimum structure difference (Defect). Useally pre-doping method was used for producing boron-doped CNT. However, mixed boron source could affect the chemical reaction during synthesis, and then both of macro- and micro-structure of final product was changed.

In this study, we used metallicity-separated single-wall CNT (SWNT, metallic-SWNT and semiconductive-SWNT) for boron-doping and then electric conductivity was measured. For boron doping thermal diffusion method was used to avoid structural change of CNT. XPS mesurement show that the content of substituted atom was ~0.15 at%. As a result of temperature dependence of electric conductivity, the resistivity decrease to 1/50 in semiconductive-SWNT, and increase in metallic-SWNT. The observed decreasing in resistivity could be explained by increasing of density of state (DOS) at Fermi level and formation of impurity level by boron-doping. In addition, magneticfield dependence of resistivity (MR) was measured to analyse the increasing of resistivity in metallic-SWNT. MR in metallic-SWNT was fitted by 2 dimensional weak localization theory. As a result of fitting, doped boron induced elastic and inelastic scattering was estimated as main reason for increasing of resistivity in metallic-SWNT.



462
Effects on mechanical and electrical properties improvement of nature rubber by fillers with different nanostructures
Qingshan Fu, jian Chen, Yongzhong Jin, Huazhi Zhang, Yilan Song
Key Laboratory of Material Corrosion and Protection, Sichuan University of Science and Engineering

Nanofillers are proved to be effective on reinforcement of elastomers, which can get more substantial improvements in mechanical behavior, thermal property and electrical conductivity than microfillers. At present, kinds of fillers with different nanostructures are used for formation of nanocomposites and show different properties. However, the mechanism of interaction between nanofillers and elastomers, and the key factor of reinforced effects are still ambiguous. In this study, following adding vulcanizing additives into nature rubber, three carbon nanomaterials (graphene, straight and coiled nanotubes) were filled into the nature rubber matrix for fabricating three nanocomposites in an open two-roll mill, respectively. The three nanocomposites were subjected to an XRD diffractometer, Raman spectroscopy and SEM. Tensile stress-strain properties of the three nanocomposites were measured in a dynamometer. AC conductivity of the nanocomposites was measured in a dielectric analyzer. Based on these results, we look forward to discover the relation between nanofillers’ structure and mechanical/electrical property. Further, we expect to find out the key factor of improving mechanical and electrical properties of nature rubber by nanofillers.



463
Functionalization of Carbon Nanotubes by Atomic Layer Deposition (ALD) in a Fluidized Bed Reactor
Adeliene Schmitta,*, Marius Sachsa, Christian Seidelb, Karl-Ernst Wirtha
a Friedrich-Alexander-University, Erlangen-Nuremberg, Institute of Particle Technology
b Siemens AG, Corporate Technology

Carbon Nanotubes (CNTs) provide outstanding mechanical and electrical properties, thus being interesting candidates when it comes to developing new composite materials. The inertness of the CNT surface towards chemical reactions and adhesion however, hinders an effective integration of the CNTs in commonly used matrices, e. g. resins and metals.

As a consequence the linking between the CNTs and the matrix material will fail, which is most likely to result in so-called „break-up“ effects. To overcome this problem, functional groups has to be introduced to the CNT surface, which serve as linker between the CNT surface and the matrix. Functionalization can be performed by Atomic Layer Deposition (ALD), which consists of splitting a common Chemical Vapour Deposition (CVD) reaction into two alternating and self-limitating reaction sequences A and B; thus allowing the formation of very thin and pure metal oxide layers.

The ALD process works batchwise and is mainly applied on semiconducting devices at the moment. In order to develop a continuous operating ALD process, which aims to functionalize CNTs on a large scale, experiments are carried out in a lab-scale ALD plant at the Institute of Particle Technology. This plant consists of a heated fluidized bed reactor (DI: 50mm), in which the CNTs are functionalized, and additional piping, as well as Mass Flow Controller (MFCs), used for precursor dosing. Fluidized Bed Reactors (FBR) provide excellent heat and mass transfer properties.

The experiments were carried out using tetraethylorthosilicate (TEOS) and water as precursors, leading to SiO2/x functional groups. Thus a more hydrophilic and reactive surface is generated and an improved linking between the CNT surface and the matrix material will be achieved. SEM/EDX, XPS, TEM, TGA and ICP-OES measurements confirm the deposition of SiO2/x. The functionalized CNTs were finally inserted in an epoxy resin (LY566). Stress tests showed a significant improvement of the composite’s mechanical properties (E-Modulus, bending strain and strength).

Studying the fluidization behaviour by differential pressure measurements and balancing of the reactor via exhaust gas analysis will provide necessary data concerning scale-up criteria. Consequently a continuous working ALD reactor concept will follow which aims to serve commercial applications on an industrial scale.



465
Evaluation of cytotoxicity and biocompatibility of carbon nanotubes in contact with tissues by spin probes
Mykola Kartela,*, Leonid Ivanova, Oleg Nardidb
a Chuiko Institute of Surface Chemistry, NAS of Ukraine
b Institute of Problems of Crybiology and Cryomedicine, NAS of Ukraine

The method of spin probes can provide information about the most important characteristics of tissue engineering - cytotoxicity and biocompatibility of nanoparticles of different origin, including the creation of interfaces between nanoparticles and tissue cells. We have devised evaluation methods of mitochondrial activity of the cells, the integrity of cytoplasmic membrane and the packing density of phospholipids (microviscosity) in the membranes of cells.

In this work we used high-purity multiwalled carbon nanotubes obtained in a pilot-install the Chuiko Institute of Surface Chemistry and TMSpetsmash-Ltd (Kiev). Toxicity of CNTs for samples of tissue homogenates was assessed by the EPR spectra to change the rate of recovery of the spin probe (water soluble stable nitroxyl radicals) by coenzyme Q10 of mitochondrial tissue that was taken proportional mitochondrial activity of the studied tissues.

It is shown selective toxicity of conventional and oxidized nanotubes to the tissues of different organs: different degrees of inhibition of mitochondrial activity of tissue homogenates or no effect of CNTs on different tissue samples. Studies show that in some cases directed functionalization of nanotubes can reduce or eliminate their toxic effects on the cells of certain organs.

We have developed a method for quantitative evaluation of the integrity of cell membranes at long-time their contact with the suspensions of nanotubes of different concentrations. The important point is that the concept of the cytotoxicity of CNTs also includes structural or conformational irreversible changes in contacted cytoplasmic components of cell membranes of tissues under the nanotube action.

Creating the hybrid CNT-based interfaces involves the introduction in a system of different substances, which increase the biocompatibility of nanotubes: polyethyleneglycol’s, dimethylformamide, propanol, etc. The spin labeled palmitic acid (fat-soluble marker), introduced into the membrane of liposome’s or erythrocytes, shows that these solvents of different directions affect on lipid fluidity (microviscosity) of membranes. In turn, microviscosity (packing density of phospholipids) of membranes of different cells affects on the functional activity of enzyme macromolecules in the cell membrane, the efficiency of ion and water channels in the membrane (membrane electrical potential), the conductivity of the nerve pulse in neurons and other processes. Therefore, registration of changes of microviscosity of cell membranes of tissues provides additional information on the biocompatibility and cytotoxicity of nanotubes, as well as the quality of the generated interfaces.



471
Microporous activated carbons prepared from sugarcane molasses
Joanna Sreńscek-Nazzala, Weronika Kamińskaa, Beata Michalkiewicza,*, Zvi Korenb
a The West Pomeranian University of Technology in Szczecin
b Department of Chemical Engineering, Shenkar College of Engineering and Design

Activated carbons (ACs) were prepared by carbonization of sugarcane molasses, which is a by-product of the vegetable sugar industry, as a natural precursor for the production of ACs. This would be a very useful new application for molasses. We show the possibility to obtain high added value materials from agriculture waste. According to our knowledge, only one short published communication deals with molasses as a raw material for ACs [1]. This communication was not followed by a full paper so the details about production of ACs from this new precursor are very limited. Further, we used KOH as the activating agent while the other authors used sulfuric acid [1]. In the present study, chemical activation and carbonization was performed in a single step by carrying out thermal decomposition of the raw material with a chemical reagent.

Carbonization, which was performed under nitrogen flow at 400-800 oC, and activation were performed simultaneously in one step. The porous texture of the produced ACs was characterized by N2 and CO2 adsorptions at 77 K. Activated carbons were characterized by XRD, FT-IR and Raman spectroscopic methods. The results indicate that ACs have a turbostratic structure and only a few impurity groups were adsorbed on their surfaces. All the ACs obtained were microporous materials and have a well-developed pore structure and high adsorption capacities The highest surface area calculated by the BET method was equal to 2202 m2/g.

The methane adsorption capacities at 25 oC and 40 bar reported by other authors were (in units of mg/g): 111.58 [2], 122.85 [3], and 136.00 [4]. Our measurements were performed at 40 oC and the methane adsorption capacity was equal to 134.12 mg/g at 40 bar. The mass of the adsorbed gas considerably depends on the temperature. The increase of the temperature causes the reduction of the adsorption. The results suggest that activated carbons prepared from molasses using carbonization and chemical activation in one step may be further developed as potential adsorbents for natural gas storage applications.

1. Legrouri, K., Khouya, E., Ezzine, M., Hannache, H., Denoyel, R., Pallier, R., Naslain, R., 2005. J. Hazard. Mater. B 118, 259–263

2. Dreisbach, F., Losch, H.W., Harting, P., 2002. Adsorption 8, 95

3. Azevedo, D.C.S., Cassia, J., Araujo, S., Bastos-Neto, M., Eurico, A., Torres, B., Jaguaribe, E.F., Cavalcante, C.L., 2007. Micropor. Mesopor. Mat. 100, 361–364

4. Lozano-Castelló, D., Alcañiz-Monge, J., de la Casa-Lillo, M.A., Carzola-Amarós, D., Linares-Solano, A., 2002. Fuel 81,1777-1803



472
Nanoparticles in Products from Sediments Brazilian Coal Mine Drainage
Silvio Taffarela,*, Marcio Kronbauera, Felipe Leãoa, Marcos Oliveirab, Luis Felipe Silvaa
a Centro Universitário La Salle, Ensino.
b Environmental Science and Nanotechnology Department, Institute of Environmental Research and Human Development – IPADH

Coal mine drainage is a major source of underground and surface water contamination in the world. The coal mine drainage (CMD) from mine contains large amount solids in suspension and a high content in nanocarbons, sulphate and dissolved metals (Al, Mn, Zn, Cu, Pb, Fe, etc.) that finally are deposited in the rivers. Since this problem can persist for centuries after mine abandonment, it is necessary to apply methods multidisciplinary to determine the potential risk in a determinate area. These methods multidisciplinary must include molecular and elemental analysis and finally all information must be studied statistically. This methodology was used in the case of coal mining acid drainage from Tubarão River (Santa Catarina, Brasil). As molecular analysis, Raman Spectroscopy, electron bean, and X-ray diffraction (XRD) have proven very useful for the study of minerals presents in the sediments rivers near of this CMD. The obtained spectra allow the precise identification of the fullerenes (C60, C70, C80), nanominerals as jarosite, Fe-oxi/hydroxide, clays, etc. The elemental analysis (Al, As, Fe, K, Na, Ba, Mg, Mn, Ti, V, Zn, Ag, Co, Li, Mo, Ni, Se, Sn, W, B, Cr, Cu, Pb and Sr) was realized by Inductively Coupled Plasma mass spectrometry (ICP-MS). Statistical analysis (Principal Component Analysis) of these dates of concentration reveals the existence of different groups of samples with specific pollution profiles in different areas of Tubarão River. Nanocarbons compounds were examined by, X-ray diffraction (XRD), and high-resolution–transmission electron microscopy (HR-TEM) with select area electron diffraction (SAED) and microbeam diffraction (MBD) modes containing hazardous elements, such as As, B, Cd, Cl, Cr, Hg, Mo, Pb, Se, Pb, U, and others hazardous elements.



473
Three-Dimensional Graphene-based Macro- and Meso-porous Frameworks for High Performance Electrochemical Capacitors
Zhong-Shuai Wu, et al.
Max-Planck Institute for Polymer Research, 55128, Mainz, Germany

Three-dimensional (3D) graphene-based frameworks (3D-GFs), such as aerogels, foams, and sponges are an important class of new-generation porous carbon materials, which exhibit continuously interconnected macroporous structures, low mass density, large surface area and high electrical conductivity.These materials can serve as robust matrix for accommodating metal, metal oxide and electrochemically active polymers for various applications in ECs,batteries, and catalysis.However, 3D-GFs generally lack well-defined mesopores and/or micropores, which substantially limits the efficiency of mass transport and charge storage for ECs through the small pores. Therefore, it is highly attractive to build up hierarchical porous architectures for 3D-GFs by integrating small mesoporous channels within interconnected macroporous frameworks.

Herein, we present the fabrication of novel 3D-GFs with hierarchical macro- and meso-porous structures. The interconnected macropores are derived from hydrothermally assembled 3D graphene aerogels (GAs) while the mesopores are generated by the silica networks uniformly grown on the surface of graphene. The resulting 3D-GFs exhibit narrow mesopore size distribution (2~3.5 nm), high surface area, and low mass density. These intriguing features render 3D-GFs a promising template for creating various 3D porous materials. Specifically, 3D GA based mesoporous carbons (GA-MC) and metal oxide hybrids (GA-Co3O4, GA-RuO2) can be successfully constructed via a nanocasting technology. Benefiting from the integration of meso- and macro-porous structures, 3D GA-MC manifests outstanding specific capacitance (226 F g-1), high rate capability and excellent cycling stability (no capacitance loss after 5000 cycles) when it is applied in electrochemical capacitors.



474
Heterogeneous Model of hexane adsorption on fixed bed of carbon aerogels by transient balance equation into porous particle.
Diego Camargo-Trillosa,*, Farid Chejnea, Elizabeth Pabon-Gelvesa, Carlos Moreno-Castillab, Francisco Carrasco-Marinb
a Universidad Nacional de Colombia
b Universidad de Granada

A base phenomenological model was developed to describe the behavior of adsorption systems at low and moderate concentrations. The model is based on partial differential equation of energy and mass balance to represent the kinetic adsorption and mass transfer at different space scales into the bed and porous material. The carbon aerogels were prepared previously by resorcinol-formaldehyde polymerization (RF), using acid and basic catalyst. Characterization of porous structure and morphology of the materials was obtained by N2 (-196 ° C) and CO2 (0 °C) gas adsorption. The specific surface areas BET up to 890 m2/g and 850m2/g were obtained for catalyst acid and basic respectively. The aerogels samples presented a high homogeneous mesopore and micropore size distribution.

Transient balance equations of gas phase into free mean of bed and particle were implemented to model the mass transport into the fixed bed of porous material. An outer transport resistance of particle, the subsequent diffusion through of macro – mesopores in particle and specific kinetic adsorption in micropores were considering by the model. The mass transport properties were associated with surface structure and morphology characteristic of carbon materials like the radio of particle, radio of microparticle, real density, porosity of particle and pore size distribution of aerogels.

At this work the implementation of boundary condition with an unique mass flux at the interface of particle, that considered the effect of kinetic adsorption on the outer surface and external film mass transfer was proposed. The kinetic adsorption in micropore of particle was represented through of Linear Driving Force model that introduced an additional transfer coefficient “kd for represent the specific rate adsorption by micropore.

The model was validated with experimental adsorption data of hexane on fixed bed of carbon aerogels, implemented the breakthrough curve methodology. The simulation of proposed model allows obtaining a good fit with the experimental uptake data of adsorption Breakthrough curve of hexane on the samples of carbon aerogels . The results of simulation showed that increasing of effective diffusivity favors the mass transport and the homogeneous saturation into the particle.The mass transfer boundary condition implemented at external particle surface represent suitable adsorption process with experimental data that allow a very good mass conservation and good representation of mass flux between the mean free of bed and pores of particle.

Keywords: Adsorption, hexane, carbon aerogels, model.



475
Activated carbon monolith production by organic binders to capture CO2.
Farid Chejnea, Adrian Betancura, Diego Camargo-Trillosa,*, Carlos Moreno-Castillab, Francisco Carrasco-Marinb, et al.
a Universidad Nacional de Colombia
b Universidad de Granada

This research is the development of a protocol suitable for the preparation of monoliths from activated carbon to adsorb greenhouses. It uses two class of activated charcoal: Norit CNR 115, it commercial coal from vegetable and activated carbon from olive stones previously activated. The synthesis of the activated carbon Norit CNR115 Queen took using carboxymethylcellulose and activated carbon from olive stones was employed Plivinilalcohol (PVA) and carboxymethylcellulose (CMC). In this work enhance the variation of percentage of binder and compaction pressure in the textural, structural and mechanical properties. To improve the selectivity of the sorvents to capture CO2 was carried out surface modification with nitrogen-rich compounds which improved the basicity of the monolith surface by generating a greater capacity CO2 adsorption.



476
Measurement methodology of Isosteras Curves on porous materials.
Farid Chejne, Diego Camargo-Trillos, Jessica Osorio, Farid Cortés, Carlos Gomez
Universidad Nacional de Colombia

Isosteres curves of the activated carbon/methanol pair were obtained based on the performance of a new device invented by the research group, the methodology to determine the characteristics of adsorbate/adsorbent pairs at equilibrium was described, particularly regarding their capacity and main thermodynamical properties. The adsorption and desorption phenomena on solid surfaces with high porosity were analyzed and the complexity inside porous materials, including properties such as morphology, energetic distribution and molecule interaction with the gaseous phase, were considered. This characterization is of great importance and relevance in the design of adsorption refrigerators, either with solar energy or gas.



477
Ordered mesoporous carbons as carriers for L-phenylalanine release
Joanna Goscianska, Anna Olejnik, Izabela Nowak, Robert Pietrzak
Faculty of Chemistry, Adam Mickiewicz University in Poznań

Mesoporous materials are interesting in delivery systems because of their outstanding features such as high surface area, great pore volumes and well–ordered pores [1,2]. Several studies have proved that different biologically active molecules can be loaded and successfully released from mesoporus materials. It has been suggested that the pore diameter of the carrier should be adapted according to the released molecule size. Therefore, in this study we try to access the applicability of various ordered mesoporous carbons such as CMK-3 and CMK-8 for loading and release of L-phenylalanine. This compound plays significant role as a precursor in the biosynthesis of L-tyrosine and is important in biochemical processes regarding the synthesis of several neurotransmitters. Phenylalanine is thought to have potential antidepressant and analgesic effects. However, on the other hand L-phenylalanine seems to exacerbate symptoms of phenylketonuria and dyskinesia in some schizophrenic patients. The results of clinical trials are not clear and more detailed research is required. In some cases L-phenylalanine is essential for human body, therefore we have developed a carrier for this compound that enables its slow-rate delivery.

In vitro release of L-phenylalanine from ordered mesoporous carbons was carried out for 48 hours in a phosphate buffer solution at three different pH - at pH 5.6 close to the isoelectric point of L-Phe, at pH 7.2 close to physiological pH and at pH 9.4. Electrostatic, and hydrophobic interactions are all likely to be important effects in amino acid release from ordered mesoporous materials. The fact that at pH 5.6 more than 50 % of adsorbed L-phenylalanine was not release is due to the strengths of the interactions between amino acid and material surface. In addition, at pH 5.6 interactions between L-Phe molecules and mesoporus carbons are high and can be responsible for close packing of L-Phe on mesoporous adsorbents. Furthermore, we suggest that L-Phe adsorbed previously at pH 5.6 could be packed inside the pores of the material, therefore amino acid could not be easily release from these materials. The higher release was observed for L-Phe in potassium phosphate buffer at pH 7.2 compared to the previous mentioned conditions. The reason could be due to the fact that amino acid was located mostly on the outer surface of the ordered mesoporous material that may have influenced the release process. The same explanation could be appropriate also for the release study carried out at pH 9.4.

1. X. Wang, P. Liu, Y. Tian, Ordered mesoporous carbons for ibuprofen drug loading and release behavior, Microporous and Mesoporous Materials 142 (2011) 334-340.

2. R. Mellaerts, J. Jammaer, M. Van Speybroeck, H. Chen, J. Van Humbeeck, P. Augustijns, G. Vanden Mooter, J. Martens, Physical state of poorly water soluble therapeutic molecules loaded into SBA-15 ordered mesoporous silica carriers: A case study with itraconazole and ibuprofen, Langmuir 24 (2008) 8651–8659.



479
Highly reactive CNTs and CNFs obtained on Ni/CeZrO2 via CO disproportionation and CH4 decomposition
Agata Lamacz, Andrzej Krzton
Centre of Polymer and Carbon Materials, Polish Academy of Sciences
Carbon nanotubes (CNTs) and nanofibres (CNFs) were obtained by decomposition of CO and CH4 on the nanosize ceria-zirconia supported Ni catalyst at temperatures ranging from 500 to 800 ○C. The formation of CNTs or CNFs was proved by the high resolution transmission electron microscopy (HRTEM), thermogravimetric analysis (TGA) and Raman spectroscopy (RS). It has been observed, that CO disproportionation over Ni/CeZrO2 yields CNTs in the whole range of applied temperatures. Whereas CH4 decomposition below 600 ○C leads to CNFs, and above this temperature to CNTs. In all cases some amount of the amorphous carbon was formed. The reactivity of obtained nanomaterials with H2O and CO2 has been studied by the experiments carried out in temperature programmed conditions (TPSR) and in isotherms. These experiments indicated that obtained nanomaterials are active in H2O and CO2 decomposition even at 350 ○C and reach the maximal reactivity at 500-550○C. High reactivity of CNTs or CNFs arises from their activation by the ceria-zirconia support. The reactivity of CNTs and CNFs obtained from CO or CH4 decomposition on Ni/MgO was found to be much lower than in the case of Ni/CeZrO2 catalyst, which is due to the inert character of MgO support. Moreover, the commercial CNTs were found to able to decompose H2O or CO2 only above 850 ○C. The evolution of functional groups formed on the surface of CNTs or CNFs obtained on Ni/CeZrO2 and Ni/MgO during H2O or CO2 decomposition was studied by the diffuse reflectance infrared Fourier transform spectroscopy. One of the purposes of our studies is to improve the knowledge about mechanisms occurring on Ni/CeZrO2 surface during steam and dry reforming reactions. High reactivity of carbon deposits, i.e. CNTs or CNFs, formed on Ni/CeZrO2 during reforming reactions, explains the increase in catalyst activity. In contrary, the presence of these carbon nanomaterials on conventional reforming catalyst, e.g. supported on Al2O3, results in their deactivation.


480
Novel Simulation Approach to Find the Performance Dependency of MOSFET-like CNTEFT on Gate Oxide Thickness
Sabbir Ahmed Khana,*, Mahmudul Hasana, Zahangir Alomb, Sourav Mahmoodc, Sharif Mohammad Mominuzzamanc
a Department of EEE,BRAC University
b Department of CSE,BRAC University
c Department of EEE,Bangladesh University of Engineering and Technology
From the concept of material science, any materials having an individual structure and characteristics have their own limitations. Due to the call for technological advancement, silicon-based integrated circuits and the scaling of silicon MOSFET design faces high complications like tunneling effect, short channel effect, gate oxide thickness effect etc. To solve these problems, new material alternatives are needed with such or better characteristics. Recently, carbon nanotube has caught the attentions with promising future to replace silicon-based materials due to its superior electrical properties and characteristics.New Simulation studies of MOSFET-like carbon nanotube field-effect transistors (CNTFETs) are presented using models of increasing rigor and versatility that have been systematically developed. Also, analysis has been made to see the effect of gate oxide thickness change in particular on the drain current. The purpose of this paper is to study the effect of Gate Oxide thickness on CNTFET and the main focus is on the simulation of its current-voltage (I-V) characteristic with new modified simulation method. The simulation study is carried out using MATLAB program and the result obtained is used to compare the device performance with MOSFET. Besides,further analysis has been done through the comparison of the simulation result of the other research groups to justify the results.


481
Fabrication of nanostructures from thermal-treated N-doped multiwalled carbon nanotubes: nanoparticles, nanoribbons, junctions and coalesced nanotubes
Emilio Munoz-Sandovala,*, Yadira Vega-Cantúb, David Meneses-Rodríguezc, Ana Elíasd, Mauricio Terronese, et al.
a Advanced Materials Division, IPICYT, Camino a la Presa San Jose 2055, SLP, SLP, 78216, Mexico.
b Advanced Materials Division, IPICYT, Camino a la Presa San Jose 2055, SLP, SLP, 78216, Mexico
c Instituto de Microelectronica de Madrid, IMM (CNM-CSIC), C/Isaac Newton 8 (PTM),E-28760 Tres Cantos (Madrid), Spain.
d Department of Physics, Department of Materials Science and Engineering & Materials Research Institute, The Pennsylvania State University, University Park, PA 16802-6300, USA.
e Research Center for Exotic Nano Carbons (JST), Shinshu University, 4-17-1 Wakasato, Nagano City 380-8553, Japan.

N-doped multiwalled carbon nanotubes (CNxMWNT) have been thermally treated at atmospheric pressure in order to obtain different nanostructures. Chemical vapor deposition (CVD) grown nanotubes were produced using a benzylamine and ferrocene precursor solution. CNxMWNT were suspended in methanol and dispersed in an ultrasonic bath. This suspension was placed inside an alumina boat for the heat treatment. A quartz reaction tube with a controlled inert atmosphere was used (low flow, namely 1 bubble per second). CNxMWNT heat treatments were carried out at 1000 and 1100 °C during different times, ranging from 16 to 36 hours. The obtained nanostructures were characterized by SEM, TEM and Raman spectroscopy. Nanoparticles, nanoribbons, junctions and coalesced nanotubes were found in the products. Mechanisms responsible for the formation of these diverse nanostructures will be discussed. The N-doped nanoribbons may find applications in electronics, including sensors, field effect transistors, and field emission sources. Ferromagnetic nanoparticles have importance in nanobiomedicine. Carbon nanotube junctions and coalescence are important phenomena, since they constitute building blocks for hierarchical nano-electronic devices.



482
Polymer-derived carbon materials with bimodal pore size distribution
Maryam Peer, Ali Qajar, Ramakrishnan Rajagopalan, Henry C. Foley
The Pennsylvania State University

Porous carbon materials are of great interest in a wide range of applications including gas adsorption and separation, catalysis, fuel cells and capacitors. Polymer-derived porous carbon prepared by pyrolysis of synthesized polymers have been increasingly studied by researchers since their textural and morphological properties can be controlled by careful choose of monomer and controlling polymerization condition. We as a group have been using furfuryl alcohol which is a cheap and available biomass-derived monomer to synthesize microporous carbon with unique textural properties and inert surface chemistry. Polyfurfuryl alcohol-derived carbon has been used for gas adsorption and catalysis in our group and has shown great performance in both applications. To use carbon as catalyst support, control over its porosity and pore size is a big challenge which has been dealt with in literature by hard and soft templating. In this study, we have used different monomers (substituted furan rings) and also mixtures of furfuryl alcohol and phloroglucinol to synthesize carbon with a bimodal pore size distribution and to control the size of the pores in the micropore and mesopore region. This kind of bimodal porosity gives carbon superior properties such as facilitated mass transfer due to presence of mesopores and molecular sieving effect because of micropores. Different approaches were taken to control the porosity and pore size and methyl chloride gas adsorption measurement was conducted to investigate the effect of each approach on carbon pore size. Carbons with bigger pores can be used as catalyst supports for bigger/bulkier reactant molecules. Creating controlled amount of mesoporosity (with a specific pore size) improves catalyst activity by decreasing mass transfer limitation.

Carbon derived from polyfurfuryl alcohol has an average pore size of 0.5 nm and that made of phloroglucinol polymer has a mesoporous structure with the average pore size of 8-9 nm. It was observed that by mixing these monomers bimodal carbon with both micro and mesopores can be synthesized.



483
Evaluation of activated carbon impregnation with copper and palladium for the removal of sulfur and nitrogen compounds present in diesel oil
Fulvy Pereiraa,*, Antonio Souzab, Selene Souzab, Carlos Yamamotoa, Sandra Chiaroc, et al.
a Universidade Federal do Paraná
b Universidade Federal de Santa Catarina
c PDAB/HPE - CENPES/PETROBRAS

The consumption of liquid fuels (such as gasoline and diesel) is increasing worldwide, because of this, heavier oil processing in refineries has been performed, so that the demand for these fuels be satisfied. However, these heavier oils contain very high levels of sulfur and nitrogen compounds, which cause damages to human health and to the environment, and due to these problems new stricter regulations on the content of these compounds in diesel oil are being established. Hydrodesulfurization process is used in refineries for the removal of sulfur compounds and is already being modified (increased operational conditions, like temperature and pressure) to enhance its ability to remove sulfur compounds, but the processed oil presents high levels of sulfur compounds that are refractory to this process, in addition to nitrogen compounds that affect the sulfur removal. For these reasons, a supplement unit to hydrodesulfurization is needed to reduce the total sulfur content to levels required by legislation (approximately 10 mg.Kg-1). The adsorptive desulfurization with activated carbon has been widely studied as alternative, since it can reduce the sulfur content of diesel to very low concentrations, using ambient conditions of temperature and pressure, without high energy costs. The present study evaluated the impregnation of activated carbon from babassu coconut, with copper, palladium and mixtures of copper and palladium (30, 50 and 70 wt %) in the adsorption of nitrogen and sulfur compounds present in commercial diesel, product of hydrodesulfurization . Physical and structural characteristics were analyzed before and after activated carbon impregnation with copper, and the results of nitrogen adsorption presented a reduction on BET area, on the external surface area and micropores area of the impregnated activated carbon in relation to the original activated carbon. This fact was also observed in photomicrographs obtained by scanning electron microscopy, in which the visible pores on the surface of activated carbon before impregnation were filled with copper metal after impregnation. Even with the reduction in textural parameters of activated carbon, occurred significant improvements in the adsorption of nitrogen and sulfur compounds present in diesel. The copper impregnated activated carbon presented reduction of 53% for sulfur compounds and 97% for nitrogen compounds, initially presents in diesel fuel. The carbon impregnated with palladium reduced 75 % of sulfur content and 96% of nitrogen content in commercial diesel. The better result for mixture removed 67% of total sulfur, and 96% of nitrogen. Such results are extremely important, because the activated carbons tested removed a large amount of nitrogen and sulfur compounds present in diesel, and show the activated carbon impregnated with copper and palladium as a viable alternative to the complementary process of hydrodesulfurization.



484
A new ceramic-carbon hybrid made from organoclay and functioning as a reinforcing filler and a binder for carbon/carbon composites and as a high-temperature structural monolith
Andi Wang, Xiaoqing Gao, Rossman F. Giese, Jr., D.D.L. Chung
University at Buffalo, State University of New York

Carbon/carbon (C/C) composites are important as high-temperature lightweight structural materials, as used for reentry vehicles, missiles and aircraft brakes. In addition, they are valuable for biomedical and corrosion-resistant applications. However, they suffer from high processing cost, which is due to the need to use multiple impregnation-carbonization cycles and methods such as chemical vapor infiltration (CVI) in order to achieve sufficient densification and hence adequate mechanical properties.

This work is primarily aimed at (i) investigating the mechanical properties of C/C composites containing organoclay through filler incorporation and elucidating the structure of this multi-scale composite, (ii) investigating the feasibility and effect of conversion of the organic component of organoclay to carbon and the associated feasibility of forming a ceramic-carbon hybrid and a monolithic material from organoclay in the absence of any other ingredient, (iii) investigating the feasibility of organoclay serving as both filler and binder at the same time, (iv) investigating the feasibility of using organoclay incorporation to facilitate the low-cost fabrication of C/C composites without densification, and (v) investigating the feasibility of using organoclay in the absence of any other ingredient to form a low-cost monolithic structural material.

A unidirectional carbon/carbon composite exhibiting flexural strength 290 MPa, modulus 55 GPa and toughness 2.9 MPa is obtained by 1000°C 21-MPa hot-press carbonization of a mesophase-pitch-matrix carbon-fiber composite without densification, but with incorporation of a new ceramic-carbon hybrid nanostructured filler/binder (86 vol.% ceramics, 14 vol.% carbon) formed from montmorillonite organoclay (d001 31.5 Å) during carbonization. The composite with the filler contains 50 vol.% fibers, 33 vol.% carbon matrix, 5 vol.% filler and 12% porosity. Despite the porosity increase from 10% to 12% upon filler incorporation, the thermal stability is improved. Despite the fiber content decrease from 53 to 50 vol.%, the flexural strength and modulus are increased by 64% and 46% respectively relative to the composite without filler or densification, and by 46% and 14% respectively relative to the composite without filler but with densification. Hot pressing the organoclay alone forms a black monolithic sheet with thermal stability superior to C/C composites, electrical resistivity 6 x 106 Ω.cm, flexural strength 180 MPa, modulus 69 GPa, low ductility, low toughness, and phases including mullite, cristobalite, disordered clay, ordered graphite and disordered graphite. Without the organic component, the sheet is grey, with higher resistivity and lower binding ability, strength, modulus and toughness.



485
Through-thickness piezoresistivity in a carbon fiber polymer-matrix structural composite for electrical-resistance-based through-thickness strain sensing
Daojun Wang, D.D.L. Chung
University at Buffalo, State University of New York

The sensing of strain and damage of a structure is practically important for load monitoring, operation control, structural vibration control and structural health monitoring. Piezoresistivity (change of the volume electrical resistivity with strain) in continuous carbon fiber polymer-matrix structural composites allows electrical-resistance-based strain/stress sensing.

In carbon fiber composites, strain can cause a partly irreversible change in the microstructure even if it is in the elastic regime. An example of a microstructural change is a change in the degree of fiber-fiber contact. The fiber-fiber contact stems from the fiber waviness and the consequent presence of points at which a fiber is locally in electrical contact with an adjacent fiber. The electrical contact, which is to be distinguished from a physical contact, allows the tunneling of electrons from one fiber to another, thus resulting in percolative conduction. Tunneling requires the adjacent fibers to be separately by a sufficiently small distance (of the order of Angstroms) at the contact point. A statistical increase in the number of contact points, as enabled during loading (such as compression in the direction perpendicular to the general direction of the fibers) by a very slight increase in the proximity between the adjacent fibers, can cause a decrease in the resistivity in the direction perpendicular to the general direction of the fibers. In this paper, an increase in the number of contact points is referred to as an increase in the degree of fiber-fiber contact.

The objectives of this paper are (i) to extend the technology of electrical-resistance-based strain/stress/damage self-sensing of carbon fiber polymer-matrix composites from uniaxial longitudinal (in-plane) loading and flexural loading to uniaxial through-thickness loading, and (ii) to address the science behind the through-thickness piezoresistivity, with attention on the effects of through-thickness stress on the through-thickness and longitudinal resistivities.

Uniaxial through-thickness compression is encountered in fastening. As shown for a 24-lamina quasi-isotropic epoxy-matrix composite, compression results in (i) strain-induced reversible decreases in through-thickness and longitudinal volume resistivities, due to increase in the degree of through-thickness fiber-fiber contact, and (ii) minor-damage-induced irreversible changes in these resistivities, due to a microstructural change involving an irreversible through-thickness resistivity increase and an irreversible longitudinal resistivity decrease. The Poisson effect plays a minor role. The effects in the longitudinal resistivity are small compared to those in the through-thickness direction, but longitudinal resistance measurement is more practical. The through-thickness gage factor (reversible fractional change in resistance per unit strain) ranges from 2.6 to 5.1 and the reversible fractional change in through-thickness resistivity per unit through-thickness strain ranges from 1.5 to 4.0, both quantities decreasing with increasing strain magnitude from 0.19% to 0.73% due to the increasing irreversible effect. The irreversible fractional change in through-thickness resistivity per unit through-thickness strain ranges from -1.0 to -1.3 and is strain independent. The effects are consistent with the surface resistance changes previously reported for the same material under flexure.


486
The cell wall of exfoliated graphite as a nanoscale viscoelastic material
Po, H. Chen, D.D.L. Chung
University at Buffalo, State University of New York

Viscoelastic solids are valuable for vibration damping and mechanical isolation. The viscoelastic behavior of exfoliated graphite has not been previously studied with focus on the cell wall in the cellular structure of exfoliated graphite. This work involves dynamic mechanical testing of exfoliated graphite compacts, using a sinusoidal stress wave at a controlled frequency.

The cell wall (with about 60 graphite layers thick on the average) is viscoelastic, due to the shear between graphite layers. The viscous character of the cell wall decreases with increasing solid content (corresponding to increasing compaction pressure), due to the increasing difficulty of shear between the graphite layers. The elastic character of the cell wall is essentially independent of the solid content, essentially in accordance with the Rule of Mixtures, though it tends to decrease slightly with increasing solid content.

The viscous character is greater under in-plane flexure than uniaxial compression in the compaction direction, due to the preferred orientation of the graphite layers in the plane perpendicular to the compaction direction and the consequent stiffness anisotropy. At the lowest solid content of 1.0 vol.% (99.0 vol.% voids), the loss-tangent/solid-content is 35 and 25 under flexure and compression respectively, the storage-modulus/solid-content is 125 MPa and 46 kPa under flexure and compression respectively, and the loss-modulus/solid-content is 45 MPa and 13 kPa under flexure and compression respectively. The loss-tangent/solid-content decreases with increasing solid content, leveling off at 0.9 at 15 vol.% solid, whether under flexure or compression. The loss-modulus/solid-content decreases with increasing solid content, leveling off at 6 vol.% solid at 19 MPa and 6.1 kPa for flexure and compression respectively. The shear-driven viscous character occurs extensively under flexure only when the solid content is below 4 vol.%.

The cell wall of exfoliated graphite is superior to rubber and the solid part of a carbon black compact in the viscous character, the stiffness and the mechanical energy dissipation ability. The highest values of the loss-tangent/solid-content, the storage-modulus/solid-content and the loss-modulus/solid-content are much greater for an exfoliated graphite compact than rubber or a carbon black compact.



487
Electrical and dielectric properties of carbon particle paste electrodes and of the electrode-metal interface, including comparative evaluation of various carbons
Andi Wang, D.D.L. Chung
University at Buffalo, State University of New York

Carbon electrodes for electrochemical devices are commonly in the form of a paste. An electrode is commonly characterized in terms of its effectiveness in a particular device, which involves electrodes and an electrolyte. Although this application-oriented method of characterization is important, it does not allow characterization of the behavior of the components of the cell in a decoupled manner and does not allow characterization of the properties of specific interfaces. The properties of an electrode encompass at least (i) the volume electrical resistivity, (ii) the contact resistivity ( the resistivity of the interface between the electrode and the electrical contact), (iii) the relative dielectric constant (which relates to the volumetric capacitance) and (iv) the specific interfacial capacitance (which is the capacitance per unit area of the interface between the electrode and the electrical contact). Low values of the volume resistivity and contact resistivity are desired for a low resistance in the cell; a high value of the relative dielectric constant is desired for strong interaction between the electrode and the applied electric field; and a high value of the specific interfacial capacitance is desired for the interface to contribute little to the capacitance of the cell. This work addresses the properties of the electrodes rather than the cell, thereby providing new information about how the carbon solid and the liquid electrolyte contribute to governing the four properties mentioned above. The objectives are (i) to characterize electrolyte-filled carbon electrodes in terms of the volume electrical resistivity and the relative dielectric constant, (ii) to characterize the interface between an electrolyte-filled carbon electrode and its electrical contact in terms of the contact electrical resistivity and the specific capacitance (i.e., capacitance per unit area), (iii) to determine the contributions of carbon and the electrolyte to each of the electrical and dielectric properties mentioned above, (iv) to characterize the interplay between carbon and the electrolyte in the electrical and dielectric behavior, and (v) to provide a comparative evaluation of natural graphite, exfoliated graphite, carbon black, activated carbon and activated GNP in the effectiveness for providing high-performance electrolyte-filled carbon electrodes.

The electrical conduction and dielectric properties of carbon particle electrolyte-filled pastes for electrochemical electrodes are reported, with the contributions of the carbon, electrolyte (sulfuric acid in water) and interface (between the electrode and the copper electrical contact) decoupled and determined. Activated graphite nanoplatelet (GNP, relative-dielectric-constant/specific-surface-area = 5.5 g/m2) paste is more attractive than activated carbon paste, exfoliated graphite paste, natural graphite paste and carbon black paste, as shown by high values of the relative dielectric constant and the specific interfacial capacitance and low values of the volume and contact electrical resistivities. The addition of exfoliated graphite to activated GNP in a 1:3 ratio decreases the volume and contact resistivities and improves the handleability. The relative dielectric constant of the carbon solid is lower than that of the electrolyte for natural graphite, exfoliated graphite and carbon black pastes, but is higher for activated carbon and activated GNP pastes. The electrical resistivity of the carbon solid is higher than that of the electrolyte for natural graphite, activated carbon and activated GNP pastes, but is lower for exfoliated graphite and carbon black pastes. The interfacial capacitance is much increased and the interfacial resistivity is much decreased by the addition of the electrolyte.



490
Appearance of Edges of Miniaturized Carbon Fibers Produced by Electrochemical Processing and Their Evaluation
Masahiro Toyoda, Hiroyuki Hara, Taro Kinumoto, Tomoki Tsumura
Dept. Applied Chemistry, Oita University

Preparation of miniaturized nanometer sized carbon fibers (Exfoliated Carbon Fibers; ExCFs) have been carried out by electrochemical treatment and following rapid heat-treatment. Shape of its fiber has changed to the scale-like morphology in PAN-based carbon fibers and bundle of thin filament along the fiber axis in Pitch-based carbon fibers. ExCFs of PAN- and pitch-based carbon fibers have a large amount of edges which are seldom observed in carbon nanotubes because they have gone through the formation of graphite oxide and miniaturization. This was clarified by the analysis of thermal programmed desorption and temperature programmed oxidation of the ExCFs. Carboxyl groups were generated at the edges by electrochemical processing. Subsequently the number of carboxyl groups decreased as a result of the rapid heat treatment, while the number of oxygen functional groups derived from CO increased. The differences in morphology of ExCFs prepared from PAN- and pitch-based carbon fibers seem to reflect the texture of the initial carbon fibers.

* Corresponding author; toyoda22@oita-u.ac.jp



491
Enhancing the dimensionless thermoelectric figure of merit of carbon fiber polymer-matrix composite in the through-thickness direction by four orders of magnitude
Seungjin Han, D.D.L. Chung
University at Buffalo, State University of New York

The conversion of thermal energy to electricity provides clean energy and can use thermal energy that is largely untapped. For large-scale thermoelectric energy conversion, it is important to have thermoelectric materials that can be formed into large bulk cost-effective devices. As the electrical resistance is inversely proportional to the area perpendicular to the resistance direction, a large area of the thermoelectric material in the plane perpendicular to the temperature gradient is valuable for providing a small resistance and hence a high electric power. Thermoelectric structural materials are potentially attractive for large-scale energy harvesting and enable self-powered structures.

The objectives of this paper are (i) providing the scientific basis for understanding the thermoelectric power of composite materials, which necessarily involve interfaces, (ii) decoupling the interfacial and bulk contributions to the thermoelectric power, as such decoupling has not been previously attained and is critical to the understanding of the factors that govern the thermoelectric power of a material with interfaces, (iii) decoupling the lamina and interlaminar interface contributions to the thermoelectric power of a carbon fiber/polymer composite laminate in the through-thickness direction, (iv) enhancing the thermoelectric power of carbon fiber/polymer composites in the through-thickness direction, (v) evaluating and increasing the ZT of carbon fiber polymer-matrix composites, and (vi) studying the effects of the curing pressure and interlaminar fillers on ZT.

Through filler incorporation and unprecedented decoupling of the bulk (laminae) and interfacial (interlaminar interfaces) contributions to the Seebeck voltage (through-thickness Seebeck voltage of a crossply continuous carbon fiber/epoxy composite laminate), this work provides thermoelectric power magnitudes at ~70°C up to 110, 1670 and 11000 μV/K for the laminate, a lamina and an interlaminar interface respectively. The interface provides an apparent thermoelectric effect due to carrier backflow. The interfacial voltage is opposite in sign from the laminate and lamina voltages and is slightly lower in magnitude than the lamina voltage. An interlaminar filler, particularly a thermoelectric filler (tellurium or bismuth telluride), enhances the magnitudes of the voltages and thermoelectric powers of the laminate, lamina and interlaminar interface. Bismuth telluride results in negative values of the voltages and thermoelectric powers of the laminate and lamina; tellurium results in positive values. Tellurium content increase or tellurium particle size decrease enhances the magnitudes of the voltages and thermoelectric powers of the laminate, lamina and interlaminar interface. Decreasing the curing pressure decreases these magnitudes, due to fiber-fiber contact decrease. The resistance-related voltage at each electrical contact is unprecedentedly decoupled from the thermoelectric specimen voltages. By adding tellurium particles (13 vol.l%), bismuth telride particles (2 vol.%) and carbon black (2 vol.%), the thermoelectric power is increased from 8 to 163 µV/K, the electrical resistivity is decreased from 0.17 to 0.02 Ω.cm, the thermal conductivity is decreased from 1.31 to 0.51 W/m.K, and the dimensionless thermoelectric figure of merit ZT at 70°C is increased from 9 x 10-6 to 9 x 10-2. Tellurium increases the thermoelectric power greatly. Bismuth telluride decreases the electrical resistivity and thermal conductivity. Carbon black decreases the electrical resistivity.



492
Functionalization of textiles with nanostructured carbon materials
Alexandra G. Gonçalvesa, José F. Silvab, Carla J. Silvab, Cristina Freirec, Manuel Fernando R. Pereiraa,*, et al.
a Laboratório de Catálise e Materiais(LCM), Laboratório Associado LSRE/LCM, Departamento de Engenharia Química, Faculdade de Engenharia, Universidade do Porto, 4200-465 Porto.
b Centro de Nanotecnologia e Materiais Técnicos, Funcionais, e Inteligentes (CENTI), 4760-034 Vila Nova de Famalicão
c REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, 4169-007 Porto.

Multi-walled carbon nanotubes (MWCNTs) and Carbon Black (CB) were functionalized with oxygen-containing surface groups and subsequently incorporated into cotton and polyester fabrics by a process that mimics the traditional industrial dyeing process. The washing fastness, hydrophobicity, flame retardancy and bulk conductivity of the functional textiles were evaluated. The MWCNTs and CB surface chemistry was modified by three different routes: (i) liquid phase oxidation with nitric acid, in order to introduce acidic oxygen-containing groups, (ii) thermal treatment of the samples oxidized in the previous step in order to remove the carboxylic acid functionalities and (iii) gas phase oxidation with 5% oxygen in nitrogen to incorporate basic and neutral groups. Some of the modified CBs were further functionalized with the incorporation of an organosilane. All samples were characterized by temperature programmed desorption, pH at the point of zero charge and N2 adsorption–desorption isotherms at -196 ºC. The CBs functionalized with the organosilane were also characterized by X-ray spectroscopy. The effect of the MWCNTs and CB acidity/basicity and of the type of textile substrate in the nanomaterials incorporation efficiencies and in the performance of the final textile materials was assessed. Some samples of cotton fabrics were submitted to a plasma treatment prior to the incorporation of the carbon materials, in order to evaluate the effect of the cotton surface groups. The scanning electron microscopy images and the whiteness degree values of the functional textiles before and after washing indicated that the incorporation efficiency was higher for the textiles containing the most acidic carbon materials, especially for the polyester textiles. The immobilization of the less acidic MWCNTs in polyester imparted hydrophobic properties to the fabrics surface; in particular, the polyester samples functionalized with unmodified and O2-oxidized MWCNTs presented an almost superhydrophobic behaviour. In the case of the cotton-based samples, a hydrophobic behaviour was not achieved. The flame-retardant properties of both substrates improved upon the MWCNTs immobilization, which was not observed in the case of the CB immobilization. Acknowledgments: This work was funded by Fundação para a Ciência e a Tecnologia (Portugal) and FEDER, through project PTDC/CTM/108820/2008 in the context of Programme COMPETE. C.P. thanks FCT for a grant.



493
Mass Production of Graphene Through High-Speed CVD Process
Kazuo Muramatsua, Kohichi Sutania, Masahiro Toyodab,*
a Incubation Alliance, Inc.,
b Dept. Applied Chemistry, Oita University,

Graphene is the basic structure of which graphite is composed, and has commonly been known for some time by technical terms such as hexagonal lattice carbon. Different types of carbon materials are all multilayered structures of graphene. Carbon materials with a variety of properties have been designed and produced based on different lamination methods and orientations of graphene. However, its preparation method was still experimental and large amount of preparation is difficult. Incubation Alliance Inc. has used a proprietary high-speed CVD process to successfully mass-production of graphene without the use of substrates, catalysts, or stripping. “Graphene flower” (registered trademark) is a mass of graphene that has been grown into individual flower pedal shapes, which together form a unified mass of graphene. From observation SEM image of Figure, it shows the external appearance of Graphene flower. The graphene that forms the Graphene flower uses a bottom-up method to grow the graphene from a small geometry, singlelayer shape to a geometry of several layers of about 10 μm. Then, from TEM image, we can confirm that the graphene is about 2 nm thick, which means it is composed of only 7 layers. The layer number estimated from the Raman spectrum was 3 or 4.

* Corresponding author; toyoda22@oita-u.ac.jp



495
Functionalization and Characterization of Multi-Walled Carbon Nanotubes/Polyaniline Composites
Cristal M. Ibañeza,*, Celso P. De Melob, Yadira I. Vega-Cantuc, Humberto Terronesd, André Galembecke
a Programa de Ciência de Materiais, Universidade Federal de Pernambuco, 50670-901 Recife, PE, Brazil
b Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, PE, Brazil
c Advanced Materials Department, IPICYT, Camino a la Presa San José 2055, Lomas 4a. Sección, San Luis Potosí 78216, México
d Pennsylvania Department of Physics, The Pennsylvania State University, 104 Davey Lab, University Park, Pennsylvania 16802-6300, United States
e Departamento de Química Fundamental, Universidade Federal de Pernambuco, 50670-901 Recife, PE, Brazil

The synthesis of polyaniline (PANI) containing multi-walled carbon nanotubes (MWCNTs) by in situ polymerization was carried out using three different methods of MWCNTs functionalization. This study describes the synthesis, functionalization and preparation the MWCNTs/PANI composites by in situ polymerization. All the samples were characterized by X-ray diffraction, Fourier transform infrared, ultraviolet-visible and Raman spectroscopy to determine the changes in structure of the MWCNTs/PANI composites. Scanning electron microscope (FESEM) and transmission electron microscopy (HRTEM) were used to observe the coating, morphology and dispersion of the MWCNTs. The three functionalization methods have focused on improving MWCNTs dispersion because a better MWCNTs dispersion in the polymer matrices has been found to improve properties. The synthesis of MWCNTs/PANI composite starts by dispersing nanotubes in the monomer solution followed by polymerization process. Various weight percentages of MWCNTs (0, 1, 2, 5 and 10 wt.% based on the aniline monomer content) were then dispersed in a solution. The functionalization of MWCNTs improve the dispersion of them in the solution and consequently in the polymer matrix. The Raman spectroscopy shows change of the characteristics band of functionalized MWCNTs and the composites. In the FESEM and HRTEM images shows the different defects formed on ends and on the outer sidewalls of the MWCNTs after of functionalization process and slight reduction in the length (2mm to 1mm). Uniform PANI coated MWCNTs was observed and a good dispersion in the polymer matrix.



497
Characterization of NO gas sensing of modified graphene oxide by fluorination
Seho Cho, Mi-Seon Park, Yesol Kim, Young-Seak Lee
Chungnam National University

NO detecting gas sensor electrode is prepared using graphene oxide (GO) and for enhancing performance of sensing, fluorine is introduced by gas fluorination on GO. Fluorinated graphene oxide (FGO) has properties of the hydrophilic and hydrophobic simultaneously. Fluorination was carried out various condition of the temperature (R.T. ~ 400℃) at 760 torr with nitrogen: fluorine gas ratios of 9 : 1. The chemical and physical properties of the FGOs are measured through XPS and XRD and the electrical resistance is measured by using a programmable electrometer with chamber having gas flow system to evaluate the gas sensing properties of FGOs.



499
Effect of boric acid treatment on electrochemical properties of activated carbon for electric double-layer capacitor electrodes
Min-Jung Jung, Hye-Ryeon Yu, Young-Seak Lee
Chungnam National University

Electric double layer capacitor (EDLC) is performed with high power density and low specific capacitance. Accordingly, many researches were issued in EDLC for increasing a specific capacitance. The performance of an EDLC is based on the charge accumulation at the electrode/electrolyte interface, the surface characteristic of electrode material is an important factor to determine the performance of EDLC. Therefore, the controlled surface modification of electrode material is crucial for the improvement of EDLC capacity. So, in this study, boric acid treatment of activated carbon (AC), which is electrode material of EDLC, was investigated to improve EDLC performance of AC-based electrodes. The AC surface’s functional groups ratio of Quinone-like (C=O), which is electrochemical active functional group, was increased after boric acid treatment. In addition, boric acid treated AC showed an increase in the specific surface area, total pore volume, and micropore volume. In case of optimum boric acid treated AC, its specific capacitance increased up to 20 % in comparison to that of untreated AC. These results demonstrate that a boric acid treated carbon surface-based electrode effectively enhances a specific capacitance of electric double layer capacitor.



500
Effects of heat-treatment and surface modification on melt- electrospun pitch-based carbon fibers for an efficient gas sensor
Jinhoon Kima,*, Seho Choa, Sung ho Leeb, Young-Seak Leea
a Chungnam National University
b Institute of Advanced Composites Materials, Korea Institute of Science and Technology

Activated pitch-based carbon fibers (APCFs) were fabricated using a melt-electrospinning method as a NO gas sensor electrode. APCFs were prepared by thermal treatment at various temperatures (1,000, 1,650 and 2,300 °C) and activation process (using 2, 4 and 6 M KOH solutions) based on developed electrical property and porosity for a high-performance of gas sensor. Field emission scanning electron microscopy, elemental analyzer, Raman spectroscopy and pore analysis techniques were employed to characterize the prepared samples. As a result, the porosity and electrical conductivity of the prepared APCFs increased, which resulted in enlarged gas adsorption sites and an improved electron transfer. The improved porosity of the APCFs was attributed to the chemical activation process, whereas the enhanced electrical conductivity was attributed to higher heat-treatment temperature. The sensing ability of the APCFs for NO-gas was significantly improved accordingly based on the effects of the chemical activation and higher heat-treatment temperatures.



501
Effects of chemical activation on electrospun carbon nanofiber for capacitive deionization
Yesol Kima,*, Seho Choa, Min-Jung Junga, Jeen-Seok Jangb, Young-Seak Leea
a Chungnam National University
b Chungbuk Regional Small & Medium Business Administration

Capacitive deionization (CDI) is becoming essential for a water desalination process because of the increasing lack of water throughout the world. Porous carbon materials are attractive for CDI electrode because of their high specific surface areas and good electrical conductivities. In this study, a CDI electrode was constructed using chemically activated carbon fiber (ACF) and its salt removal efficiency was evaluated. CDI unite cell was constructed by electrospun ACFs. The morphology change of ACFs was investigated by using SEM. The specific surface area and pore structure were evaluated by BET and DFT equations. In conclusion, chemical activation using NaOH was carried out under various conditions to investigate the relationship between pore structure and CDI efficiency.



502
Optoelectronic properties of nitrogen doped multi-walled carbon nanotubes
Raul Arenal
LMA-INA, Universidad de Zaragoza, Spain

The incorporation of nitrogen atoms into the hexagonal network of the carbon nanotube (C-NT) walls strongly modifies the chemical and physical properties of the pure C-NT [1-4]. Even if significant efforts have been devoted to investigate N-doped C-NT, considerable progresses are still needed in order to complete the understanding and optimization of their properties. Among them, in this contribution we will focus on their local dielectric/optoelectronic properties which will be probed by low-loss EELS. In order to deeply investigate these properties, we will combine these studies with very detailed analysis of the atomic configuration, spatial distribution and concentration of dopants via spatial-resolved EELS.

This kind of studies has been possible due to the improvements developed the last two decades in transmission electron microscopes, allowing ~ 100 meV energy resolutions for a close to one angstrom electron beams and using low acceleration voltages. Thus, we have carried out these works using a FEI Titan – XFEG - Cs probe corrected microscope equipped with a monochromator (working at 80 KV and with an energy resolution below 0.25 eV).

These N-doped nanotubes (CNx-NT) present different morphologies as a function of N concentration and configuration [2-4]. Thus, we have investigated the local dielectric properties considering these aspects that we have also analyzed in parallel [7]. Furthermore, for properly analyzing the different spectroscopic modes, we have also taken into account other factors as the acquisition geometry (for probing the anisotropic effects), the thickness, the structural defects... All these results will be deeply discussed in the framework of previous experimental and theoretical works carried out in pure C-NT and compared with results coming from pure C-NT also collected under the same conditions [5-7]. In conclusion, the present study improves our knowledge of the dielectric/optoelectronic properties of CNx-NT and provides further insight into the potential applications of these materials.

References:

[1] "Boron-nitride and boron-carbonitride NTs: synthesis, characterization and theory", R. Arenal, X. Blase, A. Loiseau, Advances in Physics 59, 101 (2010).

[2] "The physical and chemical properties of heteronanotubes", P. Ayala, R. Arenal, A. Rubio, A. Loiseau, T. Pichler, Rev. Mod. Phys. 82, 1843 (2010).

[3] "Doping carbon nanotubes with Nitrogen: a route towards applications", P. Ayala, R. Arenal, M. Rummeli, A. Rubio, T. Pichler, Carbon 48, 575 (2010).

[4] "N doping in C-NT", C.P. Ewels, M. Glerup, J. Nanosci. Nanotech. 5, 1345 (2005).

[5] "Electron energy-loss spectrum of an electron passing near a locally anisotropic nanotube". D. Taverna et al., Phys. Rev. B 66, 235419 (2002).

[6] "Dielectric response of isolated carbon NT investigated by SR-EELS: From MW- to SW-NT". O. Stephan et al., Phys. Rev. B 66, 155422 (2002).

[7] R. Arenal, submitted (2013).



504
A New Approach in the Modelling and Characterization of Porous Carbon
Chunyan Fana, Phuong Nguyena, Van Nguyena, Zhonghong Zenga, Duong Dob,*, et al.
a PhD student
b Professor in Chemical Engineering

Characterization of porous carbon to determine the pore size distribution and its derivatives (surface area, pore volume and average pore size) is commonly carried out under the implicit assumption of a pore model that has slit-like pores of uniform length having both ends open to the surrounding external gas phase. It is worthwhile to point out that this assumption is not widely known to carbon practitioners. This ideal model does not adequately describe the inherently complex structure of porous carbons. An improved model should account for the following factors: (1) pore size variation along the pore axis, (2) connectivity between adjacent pores and (3) the presence of functional groups. Although some models have been proposed recently to account for structural and energetic corrugation in order to address point (1), they do not account for the effects of connectivity or the role of functional groups. In this presentation, we shall discuss recent simulation results for three basic models designed to understand the separate roles of these factors, and we shall propose a new composite pore model that better describes the structural parameters of porous carbons. The first basic model accounts for the non-uniformity of pore size along a pore axis by studying the influence of a concave or convex surface of the pore walls; the second deals with the role of the connectivity between a pore segment and adjacent pores, and the last one introduces functional groups, with an emphasis on their role in adsorption of molecules with strong dipoles and quadrupoles, such as carbon dioxide which is frequently used in characterization of microporous carbons to circumvent the severe diffusional limitation of nitrogen at 77K. We use grand canonical Monte Carlo simulation to evaluate the effects of these factors on the adsorption isotherms of adsorbates commonly used for the characterization of porous carbons, such as argon, nitrogen and carbon dioxide. It is found that different adsorbates, and variation in modelling of the adsorbent, all have significant effects on the condensation and evaporation pressures which are used in the standard procedures of inversion to determine the pore size distribution (PSD). It is recommended that existing kernels used in standard software for the determination of PSD should be modified to give an improved account of the structural properties of porous carbon.



507
Electrochemical properties of activated carbon nanofibers prepared from PAN and Pitch for electric double layer capacitor(EDLC)
Mi-Seon Park, Hye-Ryeon Yu, Min-Jung Jung, Young-Seak Lee
Chungnam National University

An electric double layer capacitor (EDLC) is popular in industries of automobile and mobile phone. But specific energy density of EDLC is low comparing with its power density. The performance of EDLC is based on charge accumulation at the electrode. The charge is accumulated by Van der waals force and physical force. In this study, activated carbon nanofiber was prepared from polyacrylonitrile and pitch that have a superior electrical conductivity. The specific energy density of the activated carbon nanofiber for EDLC electrode was confirmed by cyclic voltammetry. Activated carbon nanofiber was manufactured by electrospinning using mixed polyacrylonitrile and pitch solutions with various mass ratios (10:0, 9:1, 8:2, 6:4), stabilization, thermal treatment and activation processes. The cyclic voltammetry results showed that specific energy density increased with higher Pitch content. The highest was obtained as 251.7 F/g at a scan rate of 50mV/s.



508
Electrochemical property of phenol-based activated carbon with dual pore structure on electric double layer capacitor electrodes
Dayoung Lee, Seho Cho, Min-Jung Jung, ji-hyun Kim, Young-Seak Lee
Chungnam National University

The specific surface area and pore structure of the activated carbon electrode material are essential factors to determine the electrochemical performance of electric double layer capacitor. Therefore, the controlled pore structure of AC is crucial for the improvement of EDLC capacity. In order to improve the charge-discharge efficiency and power density, Phenol-based activated carbon materials having dual pore structure were prepared. Phenol-based carbon material with high surface area and facilitated pore development was prepared by using SiO2 template and KOH activation for mesopore and micropore, respectively. The textural properties were investigated by BET, HK, BJH and DFT methods. The electrochemical properties were evaluated using cyclic voltammetry. There was no strict correlation between the specific surface area and the template contents, whereas the mesopore volume was increased with increasing SiO2 quantity. Specific capacitance was increased with higher specific surface area and mesopore structure.



509
Carbon dioxide adsorption behavior of activated carbon nanofibers prepared by SiO2 template method
Jin-Young Junga,*, Seho Choa, Dayoung Leea, Seungkon Ryub, Young-Seak Leea
a Chung nam national university
b Jeonju Institute of Machinery and Carbon composites

Activated carbon nanofibers were prepared as a CO2 absorbent by electrospinning, thermal treatment and activation processes. KOH was used as an activation agent and activated fibers were treated at various mass ratio of silica (0, 5 ,10, 30 and 50 wt%) to investigate the effects of activation and template methods on pore structure. As-received and treated samples were labeled as 4K, 5S4K, 10S4K, 30S4K and 50S4K according to the mass ratio of silica. Surface morphologies of the prepared activated carbon nanofibers were investigated using field emission-scanning electron microscopy (FE-SEM). The physical property of activated PAN-Based CFs was investigated based on their pore size distribution and specific surface area with CO2 gas adsorption. Specific surface areas of activated carbon nanofibers are 1584~1796 m2/g and micropore volumes are comparatively similar (0.60~0.74 cm3/g). As the mass ratio of used silica increased, the micropore volume was also increased. In addition, the mesopore volume of activated PAN-Based CFs was also increased with higher amount of silica additive. The mechanism of CO2 gas adsorption/desorption was discussed based on pore structure of CFs.



510
Novel Shear Thickening Fluids based on Graphene Oxide with Improved Rheological Performance
Jie Dinga,*, Wenchao Huangb, Yanzhe Wub, Dan Lic, Cunku Dongc
a Human Protection and Performance Division,,Defence Science and Technology Organisation
b Department of Materials Engineering, Monash University
c Department of Materials Engineering, Monash University,

Recently there has been increased research in the area of shear thickening fluids (STFs) due to their potential for commercial applications. For example, they are considered possible candidate materials for liquid body armour and sporting protective clothing because of their unique properties. Graphene oxide has high mechanical strength, extremely high aspect ratio and specific surface area which make it an ideal candidate for a host of composite material applications. Here we demonstrate the effect of graphene oxide as an active component on the rheological properties and energy dissipation capability of a traditional STF of silica/ polyethylene glycol (PEG). We have found that only a very small amount of graphene oxide make remarkable contribution in rheological performance of the STF. Specifically, we have noticed that the addition of 0.3% (w/w) graphene oxide to the suspension of 15% silica (w/w) in PEG greatly facilitates the shear thickening with beneficial increases of viscosity, elastic modulus and loss modulus over one order of magnitude. The concept of using graphene oxide as an active component in STFs opens new avenues to improving performance of STFs, which may find potential applications in sports protection clothes and flexible body armour applications as they can be prepared with much lighter weights to achieve similar performance.



511
Photoelectric Conversion Properties of a CNT/TiO2 complex Working Electrode for Dye-sensitized Solar Cells
Do Young Kim, Young-Seak Lee
Chungnam National University

Dye-sensitized solar cells(DSSCs) have received significant attention as an alternative to silicon based solar cells due to their low cost fabrication and relatively high conversion efficiency. Nevertheless, despite their initial success of approximately 11% solar conversion efficiency, continued efforts to improve cell performance have not made many further breakthroughs. The carbon nanotubes(CNTs) are suitable semiconductor supports because of their combination of electronic, adsorption, mechanical and thermal properties. CNTs could offer a possible route to provide high area, interpenetrating electrodes in DSSCs. In this study, we prepared a photoanode material using the multi-walled carbon nanotubes(MWCNT)-TiO2 complex. The working electrode prepared by using electrospray apparatus. Photoelectric conversion efficiency was measured by the solar simulator and photocurrent-voltage (I-V) curve analyzer.

Keywords: Carbon nanotubes, TiO2, Dye-sensitized Solar Cells, Photoelectric Conversion Efficiency



512
Development of CNT field emitters for a high power electron source
Kim Won-Seoka,*, Kim Byung-Jooa, An Kay-Hyeoka, Kang Shin-Jaeb
a Carbon Valley R&D Division, Jeonju Institute of Machinery and Carbon composites, 110-11, Banyong-ro, Jeonju, 561-844, Republic of Korea
b Jeonju Institute of Machinery and Carbon composites, 110-11, Banyong-ro, Jeonju, 561-844, Republic of Korea

Field emission characteristics of CNT emitters were improved for an application to high power electron sources including an X-ray generating source. The effect of both the amount of CNTs and nickel inorganic fillers on field emission currents was investigated by measuring the field emission characteristics of CNT cathodes. Nickel powders which act as an adhesive between a CNT cathode and a substrate played an important role for forming cathode patterns on the substrate. The increase with CNT contents up to 7wt% in a CNT paste increased the field emission current density up to 412.5 mA/cm2 at an electric field of 5.5 V/㎛, which is available to an X-ray generating source. It was demonstrated that the increased field emission current density resulted from the increased number of CNT emitters due to the improved adhesive strength between a CNT emitter and a substrate by nickel powders. Furthermore, we obtained the field emission current density in a triode structure to be 208 mA/cm2 at an electric field of 4.5 V/㎛ with a leakage current density of 10 mA/cm2, indicating the leakage current ratio of 4.8%.



514
Molecular modelling of protein adsorption on graphite & graphene: From fundamentals to design
Mark Biggs, Matthew Penna, Milan Mijajlovic, Meisam Valizadeh Kiamahalleh, Yuhui Sun, et al.
School of Chemical Engineering, The University of Adelaide, Australia.

The adsorption of biomolecules on carbons is of relevance to their purification, the response of the body to implants, including their biocompatibility, fate of carbon nanomaterials in vivo, including their toxicology, and peptide-mediated self-assembly of carbon materials. This wide relevance has motivated us to undertake a program of research focused on using molecular simulation to build fundamental understanding of adsorption of proteins on graphite and graphene, and to exploit this new understanding to develop technologies. In this contribution, we will outline some aspects of this work, including:

  1. an until now unavailable molecular-level understanding of protein adsorption from aqueous solution on to graphite and graphene - in particular we will show the critical role played by surface-bound water in the proteinadsorption process;
  2. methods for the prediction of protein adsorption propensities and free energies for graphite and graphene - we will demonstrate that these methods are able to predict experimentally observed adsorption propensities;
  3. understanding of the conformation of MP-11, an electrochemical active enzyme, on graphene - we will show that the peptide takes on a conformation that naturally optimises its electrochemical capacity; and
  4. preliminary work focused on the design of peptides for the self-assembly of graphene-based porous structures - in particular, molecular simulation will be used to demonstrate the putative ability of de novo peptide designs to self-assemble porous graphene hydrogels of desired pore size, designs that are soon to be tested in the laboratory.


517
A Study on Pore Development of Carbon Nanofibers in the Presence of Zinc Chloride
Byung-Joo KIMa,*, Hye-Min LEEb, Hong-Gun KIMb
a Carbon Valley R&D Division, Jeonju Institute of Machinery and Carbon Composites
b Department of Carbon Fusion Engineering, Jeonju University

Electrospinning is a simple, convenient, and versatile technique for generating extremely long fibers with diameters on both the micro- and nanoscales. Continuous carbon nanofibers have been produced utilizing the electrospinning technique from solutions containing polymers, such as polyacrylonitrile (PAN), polyvinylalcohol (PVA), polyimides, polybenzimidazole (PBI), and polymer blend solutions. Following electrospinning, the as spun precursor nanofibers are high-temperature heat treated under an air atmosphere (stabilization) and finally under an inert environment (carbonization). Many of the applications of electrospun fibers could be greatly enhanced by increasing the surface area and porosity of the fibers. Importantly, the specific surface area of structures increase with increased pore volume. Porous electrospun carbon nanofibers have been produced from different precursors, such as nanofibers from bicomponent polymers or polymers and nanoparticle blends. In these cases, one of the phases in the nanofiber is eliminated during the heat treatment processes. Also, porous carbon fibers have been prepared in a manner that enables the presence of an additional metal phase or that allows the formation of the metal phase in the structure. These procedures include doping with titanium, silicon, chromium, nickel, copper, magnesium, palladium, vanadium, and iron. Owing to the catalytic behaviors of the second phase in the fibers, this process leads to the formation of porous structured carbon nanofibers during heat treatment processes.

In the study described below, a one-step electrospinning based method for the preparation of zinc-loaded, highly porous, activated carbon nanofibers (Zn/ACNFs) was developed. Various analytical techniques were utilized to investigate the morphology and material properties of the precursors and final nanofibers. In addition, the mechanism for formation of the Zn/ACNFs was developed. By adding of ZnCl2 in the nanofibers, the specific surface area were dramatically increased from 310 to 980 m2/g though the content of ZnCl2 was not optimized.

Final nanofiber diameters were also increased three times in the presence of ZnCl2 due to the thickening behaviors. In conclusion, the pore structure in electrospun carbon nanofibers can be controlly by ZnCl2 content and activation process conditions.



518
Change in the Thermal Oxidation Behavior of IG-110 after Gas Pressurization
Kim Eung-Seon, Hong Sung-Deok, Kim Yong-Wan
Korea Atomic Energy Research Institute

In a high temperature gas-cooled reactor (HTGR), polycrystalline graphite has been widely used as fuel elements, moderator or reflector blocks and core support structures owing to its excellent moderating power, mechanical properties and machinability. These graphite components may be oxidized due to impurities from a graphite outgassing and He coolant, and a leakage in a heat exchanger. The mechanical properties of graphite are severely degraded by oxidation, a reduction of 50 % in its compression strength at a burn-off of 10 % for example. Therefore, the oxidation of graphite has been widely studied to analyze the safety of the HTGR and assess the operational life of core structures. Although the coolant gas pressure is around 5~7 MPa, in most cases, the former oxidation researches were performed under atmospheric pressure. In this study, the change in oxidation behavior of a nuclear graphite, IG-110 after gas pressurization were investigated. The specimen for the oxidation test was a cylinder with a 12.5 mm diameter and 12.5 mm length. The specimens were pressurized up to 10 MPa using Ar gas. Then the specimens were dried for 3 hours at 110 oC. The oxidation tests were performed with a thermogravimeter at 550oC. It was found that as the Ar gas pressure increased the oxidation rate increased. The change in the oxidation rate was correlated with the pore structure change after the gas pressurization based on porosimetry results.



519
Developement of A Method for Converting Direct Titration Results into Boehm Titration Results
Yern Seung Kim, Taehoon Kim, Seung Jae Yang, Hyung June Kim, Chong Rae Park
Carbon Nanomaterials Design Laboratory, Global Research Laboratory, Research Institute of Advanced Materials, and Department of Materials Science and Engineering, Seoul National University, Seoul 151-744, Korea

Carbon nanomaterials such as carbon nanotubes, graphene, and fullerene are usually functionalized by various methods, and it is significant to control and determine the modified surface properties for their proper utilization. For this purpose, various methods such as X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy have been adopted for surface characterization of functionalized carbon nanomaterials.

Among the various techniques, Boehm titration method has been widely used because of its simple methodology and practical information for surface characterization. The method utilizes a selective neutralization of the reaction bases with different basicities (NaOH, Na2CO3, and NaHCO3) and three main acidic groups (carboxylic, lactonic, and phenolic groups) on the surface of the carbon nanomaterials. Particularly it is generally assumed that NaOH reacts with all of the three functional groups, while Na2CO3 reacts with carboxylic and lactonic groups, and NaHCO3 reacts only with carboxylic group.

On the other hands, several limitations interrupt the proper utilization of the Boehm titration method. For example, experimental procedures including reaction, filtration and titration are rather complicated and time-consuming comparing to the other surface characterization methods. In addition, the results from Boehm titration strongly depend on the variations of the experimental factors such as the amount of the samples reacted with the reaction bases, the concentrations of the reaction bases, and CO2 contamination. Various solutions for these problems have been developed to elucidate these problems but more fundamental consideration is necessary.

Comparing to the Boehm titration method, direct titration method is simple and the results are hardly sensitive to the experimental factors different from Boehm titration. However, interpretation of the direct titration data to provide the pK distributions is complex and these results should be further analyzed to apply them in the practical utilization.

Therefore in this paper, we develop an alternative method for converting the pK distribution function of the surface functionalities of the carbon nanomaterials from direct titration results into practical Boehm titration results, regardless of the experimental variations in the Boehm titration, adopting the modified Henderson-Hasslbalch equation. Applying the developed theory Boehm titration results with different experimental factors such as the concentration of the titrant, the quantity of the sample, and CO2 contamination was calculated and compared with the experimental results.



520
Preparation of Carbon Nano Fiber by Using Activated Carbon and Its Characteristics of Electrode for Capacitive Deionization
Lee Seon Hoa, Kim Jiyoungb, Jung Doo-Hwanc,*, Hwang Taek Sungd
a Graduate School of Green Energy Technology, Chungnam National University, 220 Gung-dong, Yuseong-gu, Daejeon 305-764, South Korea
b Advanced Energy Technology, University of Science and Technology (UST), 305-343 Daejon, South Korea
c Fuel Cell Research Center, Korea Institute of Energy Research (KIER), 305-343 Daejeon, South Korea
d Department of Chemical Engineering, College of Engineering, Chungnam National University, 220 Gung-dong, Yuseong-gu, Daejeon 305-764, South Korea

Capacitive deionization (CDI) is a removal process of ions via electrochemical adsorption using porous carbon electrodes, thus its performance largely affected by choice of electrodes. The ions are adsorbed onto the surface of porous carbon electrodes by applying electric field to brackish water. In order to improve the performance of the CDI, A highly porous activated carbon (AC) electrodes were used. it promote the growth carbon nano fiber (CNF) for increased conductivity. The well grown CNF conductivity, flexibility and mesoporous exhibit framework have promised them as effective electrode materials for CDI desalination to display effective ion capture capability. The capacitance increase may be attributed to the high surface area and suitable pore size distribution properties. Moreover, the AC grown CNF provided a high surface adsorption capability and an effective ion intercalation.



521
Revisit of Filtration Method for Aligned Carbon Nanotube Papers
Jun Young Oh, Seung Jae Yang, Yern Seung Kim, Taehoon Kim, Chong Rae Park
Department of Materials Science and Engineering, Seoul National University

Carbon nanotubes (CNTs) are one-dimensional nanomaterial to possess excellent mechanical, electrical, an, thermal properties. Unfortunately, the properties of macroscopic forms involving aggregated CNTs are quite lower than the intrinsic properties of individual CNTs. The assembly of CNTs into well-aligned structure is crucial to allow them to preserve outstanding properties of individual CNTs. Though in-situ synthesis assembly method for aligned CNTs mats with the use of chemical vapor deposition (CVD) has been widely researched, the complex condition and scalability problem limit the real application of CNTs. To prepare aligned CNTs using disordered CNTs, solution-based assembly method has been found to be attractive method. However, dispersion and low degree of alignment still remain challenges. With consideration for this situation, we report a facile preparation method to align disordered CNTs via well-known filtration method. Aligned CNTs papers have anisotropic property in macro scale and densely packed nanostructure in nano scale. We also show that the mechanical properties of aligned CNTs papers outperform that of disordered CNTs papers.



523
The effects of electrochemical oxidation of carbon fiber surfaces on mechanical interfacial properties
Kay-Hyeok An, Byung-Joo Kim, Woong-Ki Choi, Hon-Chung Chin, Woon-Bae Lee, et al.
Carbon Valley R&D Division, Jeonju Institute of Machinery and Carbon Composites, Jeonju 561-844, Korea

Thermoplastic composites are used in a variety of applications such as mass transit, automotive parts and military structures. Thermoplastic composites are attractive compared to traditional materials, such as steel, aluminum and thermoset composites for these applications, due to their high specific strength, good damping capacity, corrosion resistance, superior impact resistance, high toughness and ease of shaping and recycling. In recent year, carbon fibers are widely used as reinforcing materials in high performance composites materials. Carbon fibers present several advantages, such as high modulus and strength, good stiffness, and creep resistance. Nevertheless these advantages, the carbon fibers/thermoplastic composites has incomplete mechanical properties because of carbon fibers has poor interfacial adhesion with most of the polymers due to it is non-polar surface. The improvement of interfacial adhesion between carbon fibers and thermoplastic matrix are attributed to the presence of polar functional groups (-OH and -COOH) on the carbon fibers surface, which are able to interact with the active functional groups presented in the thermoplastic matrix. To increase the surface polar functional groups of carbon fibers, various surface treatment techniques have been applied using plasma treatment, anodic oxidation, metal plating and coupling treatment. Among the various treatments, anodic oxidation is known to be a method for improving the interfacial adhesion of between the fibers and the thermoplastic matrix. In this work, the effects of electrochemical oxidation treatment on mechanical interfacial properties of carbon fibers-reinforced polarized-polypropylene matrix composites were studied. Surface properties of the fibers, before and after treatments were observed by X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), and contact angle. Mechanical interfacial properties of the composites were measured in terms of KIC. From the investigation results, anodized carbon fibers increases in surface oxygen groups, compared with untreated carbon fibers. Additionally, it was found that O1s peaks on the fiber surfaces were strengthened after electrochemical oxidation which led to the enhancement of surface free energy of the fibers, resulting in good mechanical performance of the composites. It can be concluded that electrochemical oxidation of the carbon fiber surfaces can control the interfacial adhesion between the carbon fibers and polarized-polypropylene in this system.



524
Roles of Ozone Treatments on Interfacial Adhesion Strength of Carbon Fibers-reinforced Nylon-6 Matrix Composites
Kay-Hyeok Ana,*, Woong Hanb, Byung-Joo Kima, Seung-Il Parka, Hong-Gun Kimb
a Carbon valley R&D Division, Jeonju Institute of Machinery and Carbon Compsite
b Department of Carbon Fusion Engineering, Jeonju University

In carbon fibers-reinforced composites, the carbon fiber provides strength and stiffness while the matrix transfers the load from fiber to another via the interphase formed between the carbon fiber and matrix. An effective interface is required in an excellent composite to obtained better stress transfer and crack resistant, whereas favorable wettability is the precondition for excellent interfacial adhesion and mechanical properties of composites. A universal method to increase the surface wettability of carbon fibers is their surface modification, which raises fiber surface hydrophilicity. In order to improve the surface wettability of carbon fibers, extensive studies have been performed. Among the various methods, dry oxidation method is known to be a very efficient method for increasing the interfacial adhesion between carbon fibers and matrices in the composites. Ozone treatment, a dry oxidation method can remove impurities and introduce various oxygen functional groups, such as -COOH, -OH, and –C=O, on carbon fiber surfaces. The ozone treatment is simple, and it is possible to control the quantity of new functional groups on carbon surfaces by the ozone concentration. Also, the ozone treatment does not cause the environment problems because the ozone residue after the treatment can be totally changed into oxygen. Normally, carbon fibers-reinforced composites were prepared with thermosetting matrices, such as epoxy, unsaturated polyester, etc, by various production methods. However, thermosetting matrices can cause serious environmental problems because these composites can’t be recycled. It is why thermoplastic-based composites have been studied by many researchers. In this point of view, nylon-6 is one promising matrix which can be used ‘carbon fibers-reinforced composite’-based parts for automobiles. However, nylon-6 based composites haven’t studied exhaustively in the respect of interfacial behaviors between fillers and nylon-6. In this study, the effects of ozone treatments on mechanical interfacial properties of carbon fibers-reinforced nylon-6 matrix composites were investigated. The surface properties of ozone treated carbon fibers were studied by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectrometer (XPS), Scanning electron microscope (SEM), and contact angle measurement. Mechanical interfacial properties of the composites were investigated using critical stress intensity factor (KIC) and interlaminar shear strength (ILSS). As a result, the ozone treatments led to the high surface free energies of carbon fibers by the surface oxidation. KIC and ILSS of the ozone-treated carbon fibers reinforced composites showed higher values than those of as-received carbon fibers-reinforced composites. This result can be concluded that the mechanical interfacial properties of nylon-6 matrix composites can be controlled by suitable ozone treatments on the carbon fibers in this work.



525
CARBON NANOTUBES TO REMOVE CADMIUM FROM WASTEWATER
Nancy Perez-Aguilara,*, Vladimir Parra-Elizondob, Jesus Espinoza-Ibarrab, Angeles Escobedo-Bocardob, Paola Diaz-Floresc
a Facultad de CIencias Quimicas Universidad Autonoma de Coahuila
b Facultad de Ciencias Quimicas Universidad Autonoma de Coahuila
c Facultad de Agronomía, Universidad Autonoma de San Luis Potosi

Since more than ten years ago, several studies have demonstrated adsorption capacity of carbon nanotubes to remove heavy metals from aqueous solutions. Many of these studies used synthetic solutions of toxic metals, among others, such as lead, cadmium, copper and nickel. However, interests to the development of water and wastewater treatment technologies based on CNT´s still remain. Meaningful results showed that CNT´s should be oxidized to change their surface chemistry, before adsorption tests. Oxygen-containing groups attached to the tips and along the walls of CNT´s are adsorption sites for cations in aqueous solution. CNT´s can be oxidized with strong acidic solution such as concentrated nitric acid, concentrated sulfuric acid, or a mixture of both, under reflux at high temperature. In this research, we oxidated MWCNT´s with two solutions. The first one was a concentrated nitric and sulfuric acids solution (A), strong mineral acids; the second one was a concentrated citric acid solution (B), a weak organic acid. First results showed that both solutions (A and B) changed physical-chemical properties of CNT´s. However, CNT´s oxidized with a mixture of nitric and sulfuric acids (CNT-A) had the lower point of zero charge, pH= 4, lower than the pH=6.5 for CNT-B oxidized with citric acid. By the other hand, the total acidic sites concentration (TAS) was of 1.8 and 1.1 mmol/g for CNT-A and CNT-B, respectively. FTIR spectroscopy suggested that carboxylic groups might exist on the oxidized CNT´s surface. From these results, we used the oxidized CNT-A for equilibrium adsorption tests, to evaluate the effects of pH (pH values of 4, 5 and 6) and temperature (20, 25 and 30 °C). The results showed that pH had a significant impact in CNT´s adsorption capacity. The maximum adsorption capacity was 7.5, 14.3 and 29.8 mg/g for pH 4, 5 and 6, respectively. By the other side, adsorption is an endothermic process as demonstrated by the temperature effect in cadmium adsorption capacity; it was 7.5, 7.7 and 8.4 mg/g for 20, 25 and 30 °C, respectively. Finally, we studied the influence of the outcome of organic matter in cadmium adsorption onto CNT-A, with a wastewater sample. The experimental conditions for adsorption tests at equilibrium were a pH 5 and 25 °C, with solutions of cadmium in this wastewater; isotherms showed that cadmium adsorption capacity of CNT-A decreased, probably due to competition between CNT´s and organic matter present in the sample. Hence, organic matter from wastewater decreased the cadmium adsorption capacity of CNT´s.



526
Graphene and graphite oxide based PTT-block-PTMO copolymer nanocomposites: structure and properties
Anna Szymczyka,*, Sandra Paszkiewiczb, Zdenko Spitalskyc, Jaroslav Mosnacekc, Zbigniew Roslaniecb
a West Pomeranian University of Technology, Institute of Physics, Piastow Av. 48, PL-70310 Szczecin, Poland
b West Pomeranian University of Technology, Institute of Material Science and Engineering, Piastow Av. 19, PL-70310 Szczecin, Poland
c Polymer Institute, Slovak Academy of Sciences, Dúbravská cesta 9, 845 41 Bratislava 45, Slovakia

Nano graphene platelets (GNP; <3 layers) and graphite oxide (GO) were used as carbon nanofillers in nanocomposites based on poly(trimethylene terephthalate)-block-poly(tetramethylene oxide) (PTT-PTMO) segmented copolymer as polymer matrix. Nanocomposites with low loading of GNP and GO (0.1, 0.3, 0.5, 1 wt%) were prepared by in situ polymerization method. The dispersion and exfoliation graphene and graphite oxide nanoplatelets in polymer matrix was evaluated studied by using scanning electron microscopy (SEM), transmission electron microscopy (TEM). Both TEM and SEM showed that the graphene and GO sheets were well exfoliated and distributed uniformly in PTT-PTMO matrix. The effect of the presence of graphene and graphite oxide in PTT-PTMO matrix on phase structure and mechanical properties was investigated by using differential scanning calorimetry (DSC) and tensile tests.

This work is sponsored by European Project MNT ERA NET 2012 (project APGRAPHEL).



527
Mathematical algorithm of deposition process of a carbon films on a copper's buffer layer
Batyr Mansurov, A. Tolegen, B.S. Medyanova, Y.S. Merkibayev, A.K. Kenzhegulov, et al.
al-Farabi Kazakh National University

Various techniques, plasma-enhanced chemical vapour deposition (CVD), ion-assisted deposition, and hot filament CVD in obtaining diamond films have been developed and today are widely used. However, the characteristics achieved thus far for electronic device are not good enough for practical applications.

The majority of the processes of CVD crystallization occur in conditions of the massive chaotic crystallization of diamonds hinder the obtaining of high quality crystals.

As is generally known, such specific problems as simultaneous nucleation of non-diamond structures, flawless hindering stable growth of the oriented diamond film, the problems related with controlled growth rates, selective elimination of highly defective areas and non-diamond structural modifications of carbon films are characteristic for processes of diamond synthesis.

The above-mentioned problems may be solved through technological control by applied fields (electrostatic, magnetic, optical, temperature, field of elastic deformations) of certain limiting symmetry group.

Herewith according with the principles of crystal physics the symmetry of fields should correspond to pointed and spaced symmetry group of the diamond and not correspond to the symmetry of non-diamond modifications of carbon films.

The nucleus formation and growth rate of a crystalline film are determined rather by difference of magnitudes of thermodynamic functions of various phase conditions, than by magnitudes themselves, the difference being substantially less compared with those of magnitudes. Thus, even the insignificant variations of thermodynamic functions in the applied fields effect on the process of nucleation, the rate and direction of the crystalline structure growth.

The energy of formation of nucleus (Gn) is determined by a chemical potential (µ) of a substance, by surface energy (ð) and, as a rule, by non-considered parameters, defining effects of applied fields and their space symmetry:

Gn = µ + ð + WE + WH + WC + Whn + WSE + WSH

The additional members determine contributions of: WE - energy of the electric field, WH - energy of the magnetic field, WC - energy of the field of elastic deformations, Whn - energy of the optical influence, WSE and WSH - space symmetry of the applied fields (electric and magnetic fields).

Thus, it is possible to create conditions for preferential nucleation and growth of a diamond film through changing the magnitude and the shape of applied fields.

On the basis of the literature review and the comparison of physical and chemical properties of materials and calculations, it was showed that the copper, saturated with hydrogen, is an appropriate substrate material for heteroepitaxial growth of diamond films. The estimations have shown that it is possible to create conditions for preferential oriented growth of diamond films through changing the magnitude and configuration of applied fields. On the basis of estimated theoretical calculations the technological installation for carbon films’ growth by a method of differential magnetron sputtering has been developed and designed. The basic technological parameters of the installation are calculated. Also the mathematical algorithm of deposition process of a carbon films on a copper's buffer layer is offered.



528
Thermophysical properties of expanded graphite monoliths.
Stanislav Filimonov, Nataly Sorokina, Nikolay Yaschenko, Artyom Malakho, Viktor Avdeev
Lomonosov Moscow State University

Unique thermal stability and chemical inertia determine promising application of EG as a basis of heat-transfer layer especially in high temperature region. Heat conducting properties of exfoliated graphite monoliths mainly depends on the density and these dependencies are diverse. Herein we report about connection between heat-conducting and mechanical properties of EG monolith and the method of its production (stage number of intercalation compounds, density of the monoliths).

In order to obtain expandable graphite, a number of stages (2-5) of graphite nitrate synthesized on the base of natural graphite (d002 = 3,35 Ǻ) was subjected to hydrolysis. Thermal treatment of the expandable graphite was carried out at 900 0C. In the result exfoliated graphite with bulk density 2-7 g*l-1 was obtained. Highly porous monoliths were made by uniaxial pressing without any binders of exfoliated graphite. Heat-transfer characteristics of the materials in both parallel and perpendicular direction to the axis of compression were studied by LFA method. Determination of specific heat was performed by DSC. Mechanical properties of the monoliths were evaluated using the elastic modulus in compression and bending strength.

There was double increase of thermal conductivity during the transition from 2 to 5 stage while the elastic modulus decreased by 3 times. It was shown that the strength properties of the monoliths vary nonlinearly This behavior can be described by the theory of similarity, and the critical exponent (ζ= 1,7) is typical for a highly porous three-dimensional fragile systems[1].

Anisotropy of heat conducting properties is observed at a density of 40 kg*m-3. The anisotropy factor rises to 6 with an increase in the density up to 300 kg*m-3.

Thus, materials with very different properties can be obtained by varying the density of monoliths and nature of EG.

1. Celzard A., Mareche J.F., Furdin G.Modelling of exfoliated graphite. // Prog. Mater. Sci. 2005. V. 50. P. 93 – 179.



529
POTENTIAL USE OF CARBON ELECTRODE MATERIALS DERIVED FROM VEGETABLE BIOMASS FOR SUPERCAPACITORS
Jakpar Jandosova,*, Vladimir Pavlenkob, Francois Béguinc, Zulkhair Mansurova, Piotr Kleszykd, et al.
a Institute of Combustion Problems, Almaty, Kazakhstan
b Kazakh National Universuty, Institute of Combustion Problems, Almaty, Kazakhstan
c CRMD, CNRS-University, France; ICTE, Poznan University of Technology, Poland
d Poznan University of Technology, Poland

Different activated carbons were produced from vegetable raw materials, e.g.: rice husk, apricot stones and walnut shells, by means of chemical activation using phosphoric acid. 70% H3PO4 (ρ ≈1.54 g/cm3) was admixed to appropriate amount of rice husk or 1-2 mm fraction of walnut shells and apricot stones to make Н3РО4/precursor (wt/wt) impregnation ratio of up to 2:1. The mixtures were first precarbonized in an oven at 200 ºС for 12 hours, and then activated in self-generated atmosphere at 500 ºС for rice husk and apricot stones, and at various temperatures within range of 400-800 ºС for walnut shells. In the case of rice husk, upon carbonization, an additional method of desilication with 0.5M NaOH solution was applied. Samples were analyzed and compared using the data of argon thermal desorption, low temperature nitrogen adsorption using BET equation, and BJH-calculation scheme, methylene blue adsorption, SEM, elemental analysis and yields. Ar-BET surface area for walnut shells derived activated carbons reached the values within range of 1100-1550 m2/g. N2-BET surface area reached the value of 1690 m2/g for activated rice husk and 2030 m2/g for activated apricot stones carbon samples, total pore volumes– 1.95 cm3/g and 1.64 cm3/g, while methylene blue adsorption– 562 mg/g and 893mg/g, respectively.

The obtained carbons were used for preparation of composite electrodes using 10 % polyvinylidene fluoride binder (PVdF) and 5 % commercial carbon black. Electrochemical characterization of porous carbons in supercapacitor cell assemblies was realized using cyclic voltammetry (CV), galvanostatic cycling with potential limitation (GCPL) and electrochemical impedance spectroscopy (EIS). The effect of carbonization temperature on efficiency along with the galvanostatic charge-discharge curves were plotted. Effect of scan rate on charge propagation and capacitance has been illustrated, the effect of voltage limiting on curves of cyclic voltammetry has been shown as well. The characteristics of impedance were studied, the Nyquist plots for carbon electrode materials samples were built. Studies have suggested the possibility of using the electrode materials based on H3PO4-activated vegetable biomass in supercapacitors: specific electrochemical capacitance reached values within the range of 100-160 F/g.



530
The effects of microwave-irradiation on carbon materials
Yongil Cho
Department of Chemical and Biomolecular Engineering, Yonsei University, Seoul 120-749, South Korea

Carbon materials mainly used as a catalyst supports for Fuel cell or secondary battery that required large surface area and high electrical conductivity. In order to satisfy these, we seek to improve the electrical conductivity and surface area of various carbon materials through the microwave-radiation. Generally surface modified carbon materials can be obtained by conventional thermal treatments such as tubular furnace. However, this treatments require high temperature (>800’c) under the reducing or inert gas flow to the carbon material during at least 1 or 2 hr. Microwave can fairly reduce the reaction time and the consumption of the gases used for carbon modification.

We treated carbon materials through the microwave radiation under inert gases(N2). As a result, electrical conductivity and surface area effectively increased during short-time treatment compare to the traditional heating process. All materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-Ray Diffraction (XRD) and nitrogen adsorption (BET). And the microwave treated carbons present the increasing performance as proton exchange membrane fuel cell (PEMFC) catalysts supports & redox flow battery electrode. The performance was investigated through current-voltage (I-V) characteristics, electrode impedance and constant current charge-discharge test.



531
Effect of particle size of N-doped mesoporous carbon catalyst for oxygen reduction for PEMFC
Ulziidelger Byambasuren
Department of Chemical and Biomolecular Engineering, Yonsei University, Seoul 120-749, South Korea

Carbon supported platinum (Pt/C) is widely used in cathode catalysts for ORR. But Pt is a precious metal because of it is low abundance. So it is thus of great interest to develop Pt-free cathode catalyst for PEMFC. Therefore there are recently large interests in non Pt catalyst for PEMFC. So we investigated the effect of particle size distribution of N-doped mesoporous carbon catalyst for PEMFC cathode side. N-doped mesoporous carbon was synthesized by polyacrylonitrile as a carbon and nitrogen precursor, and three kinds of silicas which have different by particles as hard templates. Carbons were produced by pyrolysis which is a thermochemical decomposition under nitrogen and 9000C. We impregnated iron on the carbon prepared the nonprecious metal catalyst for oxygen reduction. Carbons were characterized scanning electron microscopy (SEM), transmission electron microscopy (TEM) and BET. The oxygen reduction reaction test was performed using rotating disk electrode H2SO4 solution in room temperature. A H2/O2 proton exchange membrane fuel cell (PEMFC) was constructed with the catalyst which exhibits a current density as high as 0.21 A/cm2 at 0.5V.



532
Removal of nitrogen dioxide on the carbonaceous adsorbents prepared by physical and direct activation of hay
Anna Figas, Justyna Kaźmierczak, Piotr Nowicki, Robert Pietrzak
Faculty of Chemistry, Adam Mickiewicz University in Poznań, Umultowska 89b, 61-614 Poznań, Poland

Because of their unique porous structure, easy availability as well as neutral effect on the natural environment, activated carbons have found a wide range of applications. So no wonder that their global production continuously increases. Nowadays, production of activated carbons is based on the natural organic sources, mainly hard and brown coals, wood and peat. However, literature provides many reports on obtaining activated carbons by physical or chemical activation of different kinds of waste materials of plant and industrial origin. Such solutions are appreciated both from the ecological and economical reasons.

The main aim of this study was to obtain a series of carbonaceous adsorbents from hay and their physicochemical characterization. Different preparation parameters were examined in order to evaluate the influence of activation conditions on the sorption properties of the final product.

The starting hay in the form of pellets (length 25 mm and 6 mm in diameter) was divided on two portions and subjected to pyrolysis (at 500-700ºC) followed by physical activation at 850ºC or to direct activation at 750-850ºC. The activation process was performed in a horizontal furnace under a stream of carbon dioxide with a flow rate of 250 mL/min, for 60 min.

The activated carbons obtained were characterised by elementary analysis, surface area measurements as well as estimation of the number of surface oxygen groups. The sorption capacity of the adsorbents towards nitrogen dioxide was measured in dry and wet conditions, using a mixture of NO2 and air containing 1000 ppm NO2.

The final products were adsorbents of rather low surface area, showing basic character of the surface and high nitrogen dioxide adsorption capacity.

.



533
Protein immobilization on carbon nanofibers composites for electrocatalytic oxidation of hydrogen
Helena Knopf-Marquesa, Joseph Dentzera, Roger Gadioua,*, Anne De Poulpiquetb, Elisabeth Lojoub, et al.
a IS2M/CNRS
b BIP/CNRS

Among the new carbonaceous materials, carbon nanofibers (CNFs) are one of the most promising precursors for the production of high performance sorbents. Compared to nanotubes, nanofibers exhibit a nanostructure based on graphene layer stacking which is favorable for activation and adsorption phenomena. There are mainly three types of carbon nanofibers: the herringbone in which the graphene layers are stacked obliquely with respect to the fiber axis; the platelet in which the graphene layers are perpendicular to the fiber axis; and the ribbon in which the graphene layers are parallel to the growth axis. This leads to materials with high surface areas and pore volumes while keeping a carbon structure which is relatively graphitic. Moreover, the surface chemistry of the carbon materials can be controlled by selective chemical and thermal treatments. The adsorption of proteins on a carbon surface plays an important role for research on related applications in medical or energy fields. The aim of this work was to develop materials which could be used as electrodes for bio-catalysis with hydrogenase proteins. To achieve this, the supporting materials must have good mechanical properties, a good conductivity, a significant and accessible surface area, and surface sites able to immobilize the enzyme.

The CNFs were prepared by a conventional chemical vapor deposition process using a Ni catalyst on a graphite support. The deposition was done during 0.5h under C2H2/H2 (4:1) flow. The raw product was composed of 79 wt% of CNFs, 4.20 wt% of catalyst and 16.80 wt% of graphite. In order to tailor the texture of the material, an oxidation treatment was done, which led to an increase of the BET surface from 83 m2/g to 131 m2/g. TEM images show typical fish-bone morphology of the CNFs. The surface chemistry is then modified by reduction treatment under H2. According to SEM observations, the raw CNFs exhibit a rather regular diameter, estimated values of this parameter are in range of 200nm.

The adsorption experiments were performed by immersing CNF samples in a protein solution inside an incubator at controlled temperature (23°C) for 4h. The adsorption isotherms were measured by temperature-programmed desorption with a gas trapping of the desorbed species and a quantitative mass spectrometry analysis, which allows a direct quantification of proteins adsorbed on a porous material, even when the proteins are present in low quantity. The comparison of this method with the conventional depletion methods allowed to quantify the fraction of proteins which are irreversibly adsorbed. Furthermore, the CNFs present a higher adsorption capacity (60mg/g) than that of other carbon materials like activated carbons (e.g. Maxsorb or PICA). Hydrogenase protein was then immobilized on these materials, their electrochemical performances for hydrogen oxidation were studied and good current densities were achieved.



534
Exploring electrolyte organisation and nanoporous carbon structures in supercapacitors with solid-state NMR
Michael Deschampsa,*, Encarnacion Raymundo-Pinerob, Dominique Massiotc, Francois Beguind, et al.
a CNRS-CEMHTI, University of Orleans, FRANCE
b CNRS-CRMD, Orleans, FRANCE
c CNRS-CEMHTI, FRANCE
d ICTE, Poznan University of Technology, Poznan, POLAND

Natural abundance ex-situ 13C and 11B Magic-Angle Spinning Nuclear Magnetic Resonance (MAS-NMR) have the ability to characterize the relative concentrations and environment of electrolyte species (acetonitrile and alkylammonium tetrafluoroborate) inside the nanopores of carbon for a supercapacitor charged at different voltage values.[1]

Upon charging, an extensive reorganization of the electrolyte solution is observed in our experiments, where anions are substituted by cations in the negative electrode and cations by anions in the positive electrode, as observed using a quartz microbalance and numerical simulations.[2],[3] At the positive electrode, the non-evaporable fraction of acetonitrile (either solvating an ion or adsorbed between graphene layers) remains nearly constant while at the negative electrode, acetonitrile seems to be expelled from the graphene interlayer space upon charging, as cations are bulkier than anions. Interestingly, the NMR frequencies of each species (chemical shifts) are affected by both the diamagnetic contribution of the graphene layers stemming from the graphene layer ring currents[4],[5],[6] and the paramagnetic contribution of the electronic charges carried by the carbon network.

Two non-graphitisable nanoporous activated carbons have been tested, both having relatively similar gas adsorption properties but different capacitance values and nanotextures. Upon charging, one of the carbons seems to have the capacity to undergo an expansion of the graphene interlayer spacing,[7] which might result from ion intercalation, and this carbon appears to be more disordered from Raman and NMR spectra.[8] This carbon also shows a lesser paramagnetic effect, at both the positive and negative electrodes, and such an observation may indicate a smaller local electronic density and a better repartition of the charges in its graphene layers, eventually explaining why the electrolyte in this carbon suffers less from degradation at higher voltages. Finally, we show that adding a larger amount of electrolyte allows exploring the immediate vicinity of the graphene layers using NMR exchange spectroscopy, confirming the carbon structural models obtained from numerical simulations and compatible with transmission electron microscopy results.[9]


[1] M.Deschamps et al., Exploring electrolyte organization in supercapacitor electrodes with solid-state NMR, Nature Mater. in press.

[2] M.D. Levi et al., Application of a quartz-crystal microbalance to measure ionic fluxes in microporous carbons for energy storage, Nature Mater. 8 (2009) 872.

[3] C.Merlet et al., On the molecular origin of supercapacitance in nanoporous carbon electrodes, Nature Mater. 11 (2012) 306.

[4] S.I. Lee et al., 11B NMR study of the BF4- anion in activated carbons at various stages of charge of EDLCs in organic electrolyte, Carbon 44 (2006) 2578.

[5] R.K. Harris et al., High-resolution 2H solid-state NMR of 2H2O adsorbed onto activated carbon, J. Chem. Soc.-Faraday Trans. 91 (1995) 1795.

[6] G.W. Wagner et al., Magic angle spinning NMR study of adsorbate reactions on activated charcoal, Langmuir 11 (1995) 1439.

[7] P.W. Ruch et al., A dilatometric and small-angle X-ray scattering study of the electrochemical activation of mesophase pitch-derived carbon in non-aqueous electrolyte solution, Carbon 48 (2010) 1880.

[8] M.Deschamps et al., A solid-state NMR study of C70: a model molecule for amorphous carbons, Solid State NMR 42 (2012) 81.

[9] P.J.F. Harris, New Perspectives on the Structure of Graphitic Carbons, Critical Reviews in Solid State and Materials Sciences 30 (2005) 235.



536
Elucidating the degree of spatial variation of pore characteristics within nanoporous carbon particles that undergo controlled activation
Mark Biggsa,*, Cheng Hua, Phillip Pendletonb, Francisco Rodríguez-Reinosoc, Katsumi Kanekod, et al.
a School of Chemical Engineering, The University of Adelaide, Australia.
b Sansom Institute, University of South Australia, Australia.
c Departamento de Química Inorgánica, Universidad de Alicante.
d Research Center for Exotic NanoCarbons, Shinshu University, Japan.

Whilst nanoporous activated carbons are well known to be highly disordered across multiple length scales, there are situations where it is highly desirable to minimize the degree of heterogeneity that arises from this disorder (e.g. molecular sieve-based separations; natural gas storage; supercapacitor electrodes). This has led to a number of activation methods being developed over the past two decades to reduce the heterogeneity in the pore system characteristics, particularly the degree of dispersion in the pore size distribution (e.g. [1-4]). None of these prior studies have, however, established the degree to which spatial heterogeneity has been minimized – this contribution addresses this issue for an activation method in which the char undergoes a repeated cyclic two-stage process [3], the first seeing the char being exposed to oxygen at 250ºC until the pore surface is saturated before it is in the second stage raised to 800ºC in an inert atmosphere to drive off the chemisorbed oxygen with some of the carbon. We show that this method indeed leads to the formation of a spatially highly homogeneous carbon when it is composed of 100 micron sized particles whereas these particles demonstrated, for example, up to a 10% decrease in the BET surface area from the periphery to the centre when treated using ‘normal’ CO2 activation. Further understanding of the spatial heterogeneity for the two activation methods will be provided as a function of the degree of activation and the particle size.

References

  1. Quinn DF, Holland JA. Carbonaceous material with high micropore and low macropore volume and processes for producing same. US Patent 5071820, 1991.
  2. Hu Z, Vansant EF. Synthesis and characterization of a controlled-micropore-size carbonaceous adsorbent produced from walnut shell. Microporous Materials 1995;3(6):603-612.
  3. Py X, Guillot A, Cagnon B. Activated carbon porosity tailoring by cyclic sorption/decomposition of molecular oxygen. Carbon 2003;41(8):1533-1543.
  4. Williams HM, Dawson EA, Barnes PA, Parkes GMB, Pears LA, Hindmarsh CJ. A new low temperature approach to developing mesoporosity in metal-doped carbons for adsorption and catalysis. J Porous Mater 2009;16(5):557-564.


539
Aberration-corrected scanning transmission electron microscopy based study of the variation of the nanoscale structure of a nanoporous carbon along its activation pathway
Cheng Hua, Lachlan Smillieb, Amelia Liub, Matthew Weylandc, Mark Biggsa,*, et al.
a School of Chemical Engineering, The University of Adelaide, Australia.
b School of Physics, Monash University, Australia.
c Monash Centre for Electron Microscopy, Monash University, Australia.

The radial distribution function (RDF) is a well-known means of representing the structure of non-crystalline materials at the nanoscale [1], including nanoporous carbons. Whilst RDFs have long been generated using laboratory-based X-ray machines, they are typically of modest resolution due to the low Q-ranges accessible on such machines (Q = 6-12 Å-1). Much higher resolution has been available for some time via national synchrotron or neutron facilities, but access to these is generally limited and expensive. Recent advances in transmission electron microscope (TEM) lenses and detectors means they are now not only able to facilitate the obtaining of RDFs with resolutions comparable to those obtained from synchrotron or neutron facilities, but also to do so for nanometre-scale volumes (via nano-selected area electron diffraction or nano-SAED) and for different chemical elements (via Enhanced energy loss fine structure or EXELFS) [2].

In this contribution, exploiting state-of-the-art aberration-corrected scanning transmission electron microscopy (STEM), the evolution of the nanoscale structure of a poly(furfural alcohol) (PFA)-based nanoporous carbon along the activation pathway will be elucidated through the presentation of aberration-corrected HRTEM images and RDFs derived from both nano-SAED and EXELFS. A comparison of the overall RDF obtained from nano-SAED with the EXELFS-derived RDFs for the carbon element only will also be presented with a view to elucidating the origin of the differences between them over the activation process.

References

  1. Ossi PM. Disordered Materials: An Introduction. Berlin: Springer-Verlag; 2003.
  2. Cockayne DJH. The study of nanovolumes of amorphous materials using electron scattering. Annu Rev Mater Res 2007; 37:159-87.


540
Influence of the anthracite properties in the degree of graphitization attained after heat treatment
Sandra Rodriguesa,*, Manuela Marquesa, Isabel Suárez-Ruizb, Joana Ribeiroa, Deolinda Floresc
a Centro de Geologia da Universidade do Porto. Rua do Campo Alegre, 687. 4169-007 Porto, Portugal.
b Instituto Nacional del Carbón, (INCAR-CSIC), Francisco Pintado Fe 26, 33011-Oviedo, Spain.
c Departamento de Geociências, Ambiente e Ordenamento do Território da Faculdade de Ciências da Universidade do Porto. Rua do Campo Alegre, 687. 4169-007 Porto, Portugal.

Due to economic benefits, the research for suitable precursors for the manufacture of synthetic graphite and other highly valuable carbon materials still continues. The application of anthracites in non-fuel purposes may benefit the coal extraction industry by opening potential new markets for anthracites, and simultaneously, benefit the industry of carbon and graphite materials production by using lower cost precursors. Anthracites are considered potential precursors for the production of graphitic carbon due to their specific parent characteristics. That is, the way in which each anthracite reach a graphitic structure largely depends on their previous characteristics, such as the initial arrangement of the Basic Structural Units (BSUs) into a parallel orientation, and the presence of planar pores together with high hydrogen content. Additionally, catalytic graphitization promoted by the presence of mineral matter in the raw anthracites was also found to facilitate these materials to achieve a higher structural ordering.

In this study five anthracites (PBEB, ACB, DB, AF, and ATO) with different characteristics were compared based on the texture of the raw materials as predicted by Ram RIS (Reflectance Indicating Surface) parameter, hydrogen content, and ash yield of the samples. The raw anthracites were firstly carbonized at 1000 ºC in a tube furnace, under nitrogen flow, at a heating rate of 2 ºC/min and a residence time of 1h. The carbonized samples were then heated to temperature of 2500 ºC in a graphite furnace, under argon flow, at a heating rate of 10 ºC/min and then the samples were kept at that temperature for 1h.

In order to evaluate the extent of the graphitization attained by the heat treated materials, the value of the interlayer spacing (d002, nm) and the degree of graphitization “g” [where g=(0.3440-d002)/(0.3440-0.3354)] were used as parameters that informs about the degree of graphitization reached by the anthracites after heat treatment at 2500 ºC

The highest degree of graphitization (g) was attained in the sample that shows the highest Ram value (DB anthracite, g=0.756) but also by the sample with a lower Ram value (AF anthracite, g=0.779). The difference of Ram value between these two samples is significant, 0.090 and 0.229 for AF and DB anthracites respectively. However, AF anthracite has the highest hydrogen and ash contents, which strongly contributed to its degree of graphitization.

The promotion of anthracite’s graphitization by the catalytic effect of mineral matter is evidenced by the analysis of PBEB (g=0.023) and AF samples. These two anthracites have similar Ram values (0.078 and 0.090, respectively) and hydrogen contents (2.99% and 3.01%, respectively) but differ significantly in their ash contents (6.57% and 19.74%, respectively).

Based on the results of these five samples it can be suggested that: i) for samples with a strong preferential orientation of BSUs, the hydrogen content is not so important, as the mobilization of BSUs into a parallel orientation is already present in the raw anthracite; and ii) for samples where this preferential orientation is weaker, higher hydrogen and ash contents are essential for the ability of the anthracites to graphitize.



541
Fluctuation Electron Microscopy (FEM) based study of the variation of medium-range ordering (MRO) in a nanoporous carbons long its activation pathway
Cheng Hua, Lachlan Smillieb, Amelia Liub, Matthew Weylandc, Mark Biggsa, et al.
a School of Chemical Engineering, The University of Adelaide, Australia.
b School of Physics, Monash University, Australia.
c Monash Centre for Electron Microscopy, Monash University, Australia.

Nanoporous carbons (NPCs) are typically characterized as non-crystalline materials that are disordered but not completely so. They are typically composed of stacked sp2-bonded sheets possessing curvature and defects where there is so-called medium-range ordering (MRO) between 0.5 and 3.0 nm. Structural ordering over this scale is particularly challenging for traditional diffraction techniques. Fluctuation electron microscopy (FEM), on the other hand, was developed to study MRO in tetrahedral semiconductors [1] and has been successfully applied to carbon materials to study graphitizing in annealed amorphous carbon films [2] as well as fullerene-like curvatures in graphitic carbons [3].

In this contribution, we will present FEM analysis of a series of carbons along the activation pathway of a NPC. We will show the evolution of the mesostructure and mesoporosity along the activation pathway. We will also discuss the degree of spatial heterogeneity at the mesoscale. Finally, we will present correlations between these results and those obtained from vapour adsorption.

References

  1. Gibson JM and Treacy MMJ. Diminished medium-range order observed in annealed amorphous germanium. Phys Rev Lett 1998;78(6):1074-7.
  2. Chen X, Sullivan JP, Friedmann TA, Gibson JM. Fluctuation microscopy studies of medium-range ordering in amorphous diamond-like carbon films. Appl Phys Lett 2004;84(15): 2823-5.
  3. Zhao G, Buseck PR, Rougée A, Treacy MMJ. Medium-range order in molecular materials: Fluctuation electron microscopy for detecting fullerenes in disordered carbons. Ultramicroscopy 2009;109(2):177-88.


544
Novel nanoporous carbons prepared by self-activation of biomass and their properties in supercapacitors
François Béguin, Piotr Kleszyk, Paula Ratjczak, Piotr Skowron
Poznan University of Technology

The main disadvantage of the traditional activation methods is the broadening of pores, which occurs especially for high activation degrees. In case of chemical activation, this is due to the heterogeneous mixture of solid reagents which imposes high temperatures to enhance the reactions kinetics. In recent years, we have shown that nanoporous carbons can be obtained by one-step carbonization of biopolymers, e.g., sodium alginate and the seaweeds where they are extracted from, at temperatures ranging from 600 to 900°C [1,2]. For example, the pyrolysis of sodium alginate at 600°C under argon flow results in a slightly microporous carbon (SBET = 273 m2 g-1) which contains a high amount of oxygen (15 at%) in the form of phenol and ether groups (C-OR; 7.1 at%), keto and quinone groups (C=O; 3.5 at%) and carboxylic groups (COOR; 3.4 at%) retained in the carbon framework. Despite the low BET specific surface area of this carbon, the capacitance in 1 mol dm-3 H2SO4 medium reaches 200 F g-1, i.e. a value comparable to the best activated carbons available on the market. A contribution of pseudocapacitance is clearly confirmed by the presence of cathodic and anodic humps at around –0.1 V and 0.0 V vs Hg/Hg2SO4, respectively, on the cyclic voltammograms in three electrode cell [1]. The porosity development in the material is due to sodium distributed at the atomic scale in all the bulk, allowing mild temperatures to be applied and consequently pore broadening to be reduced. Our further objective was to extend this process to alkali containing biomass precursors, grown by organized agriculture, with easy harvesting of well-defined materials. This is the case of tobacco stems and leaves; especially stems themselves are wastes from cigarettes manufacturing. The carbons were manufactured at 600°C or 900°C under nitrogen atmosphere and further washed with HCl and HF to remove the inorganic matter. The samples carbonized at 600°C are relatively rich in oxygen (16–18 %); the maximum BET specific surface area of 775 m2g-1 was observed for tobacco Burley. In opposite, the carbons manufactured at 900°C have a higher BET specific surface area (1316 m2g-1 for Burley) and less oxygen (5–6 %). The most interesting feature is the very narrow pore size distribution (PSD) for Burley tobacco carbonized at 600°C, with only ultra-micropores (<0.7 nm). Burley tobacco carbonized at 900°C possesses as well wider micropores, and in comparison to the industrial carbon DLC SUPRA 30 (Norit) prepared by steam activation of a wood precursor, it has definitely a much narrower PSD. The tobacco carbons were implemented in supercapacitor cells with 1 mol dm-3 solutions of neutral (Li2SO4), acidic (H2SO4) and organic (TEABF4 in acetonitrile) electrolytes. Their capacitance values are higher than for most commercially available carbons. The maximum values for neutral and organic electrolytes were obtained for the samples prepared at 900°C and reach 122 Fg-1 and 121 Fg-1, respectively. On the other hand, the best value of 218 Fg-1 for the acidic medium was achieved for the carbons manufactured at 600°C. References: [1] E. Raymundo-Piñero, F. Leroux, F. Béguin, Adv. Mat. 18 (2006) 1877-1882. [2] E. Raymundo-Piñero, M. Cadek, F. Béguin, Adv. Funct. Mat. 19 (2009) 1-8.



545
Cyclability improvement of Si/C composites for Li-ion batteries prepared from polyvinyl alcohol
François Béguina,*, Cyril Paireaub, Severine Jouanneaub, Encranacion Raymundob
a Poznan University of Technology
b CNRS Orléans

With a theoretical capacity of 3580 mAh/g (corresponding to the Li15Si4 alloy), silicon appears as a promising anode material for lithium-ion batteries in replacement of graphite (372 mAh/g). However, the lithium insertion into silicon is accompanied by a high volumetric expansion (~280%), leading to the disintegration of particles and loss of contact with the current collectors during charge/discharge cycling; the reversible capacity decreases while the irreversible one increases. Silicon/carbon (Si/C) composites have been proposed in literature to tentatively solve these problems. The carbon matrix in which silicon is dispersed is able to accommodate the repeated volume changes and to improve the electrical contacts. Although promising properties of these composites are often described, most of the suggested solutions are not adapted for applications, in particular because the electrodes thickness is generally very low. In this presentation, polyvinylic alcohol (PVA) has been used as water soluble and environment friendly precursor to coating silicon nanoparticles by the spray drying technique. Then PVA is cross-linked by oxidative treatment in air at 200°C and the composite is further pyrolyzed at 1050°C under nitrogen flow to get a Si/C composite. Compared to a Si/C composite without cross-linking step of PVA, the carbonisation yield is considerably enhanced and the cycleability of electrodes with PVDF binder as-well. In another set of experiments, the Si/PVA composite has been carbonised in presence of a small amount (<5wt%) of iron. Using Raman spectroscopy, it is shown that iron plays as a graphitisation catalyst which favours the development of an ordered carbon structure of high electrical conductivity. This type of carbon also leads to an enhancement of cycleability as compared with simply pyrolyzed PVA. The last strategy was the use of other binders such as polyacrylic acid (PAA) and carboxymethyl cellulose. Thick electrodes of very good cycle life could be prepared from Si/C composites together with PAA binder. Such electrodes were able to withstand 100 galvanostatic cycles at a capacity of 800 mAh/g.



546
Ultralong Carbon Nanotubes: Atomic Structural Studies
Raul Arenala,*, Per Loethmanb, Mathieu Picherb, Vincent Jourdainb
a LMA-INA, Universidad de Zaragoza, Spain
b Laboratoire Charles Coulomb, UMR 5221, CNRS, Montpellier, France

Among the potential applications of carbon nanotubes (CNT), nanoelectronics is one of the most promising [1]. Ultra-long carbon nanotubes (UL-CNT), i.e. longer than 100 µm, have an especially high potential for such applications [2,3]. However, their applicability is extremely dependent on their atomic structure which should be well-controlled and uniform along the CNT since the atomic structure determines the transport/electronic/optoelectronic properties of the CNT.

In this communication, we present our results of a deep study of the atomic structure of CVD-grown UL-CNT by electron diffraction and high resolution transmission electron microscopy. Importantly, these two techniques provide a direct characterization and determination of the atomic structure of the CNTs contrary to the indirect optical methods (Raman, photoluminescence) that are most commonly employed [4,5].

Two tens of UL-CNT have been investigated. These NT have high structural quality and we have observed that there is a marked tendency (> 2/3) of these NT to double-walled (DW). Furthermore, these DW-NT display a chiral angle and diameter correlation between the inner and outer NT which is important for the mechanical and vibrational properties of the DW-NT. For instance, we have been recently shown a mechanical coupling between two highly-correlated layers composing a DW, modifying of the nanotube vibrational properties, as it has been proven by Raman spectroscopy carried out on the same NT [6,7].

Another very important aspect that we have observed in these UL-CNT is that there is no chiral angle modification, nor diameter change along the whole nanotube length. In addition, we observed selectivity toward high chiral angles manifesting by the facts that the chiral angle of most of NT ranges between 20 and 30 deg., that 12.5 % of the NT are pure armchair and that no zig-zag NT were observed.

For the first time, we provide direct evidence that the chirality of such UL-CNT can be uniform for the whole nanotube length (several hundreds of microns). We also improved the knowledge of the atomic structure of double-walled, in particular the mechanical coupling between the 2 layers which is important to consider when extrapolating the CNT structure from optical measurements. Finally, our results provide statistical evidence of growth selectivity toward high chiral angles, a currently highly-debated topic.

References

[1] Understanding CNTs from basics to applications, Lect. notes phys., V. 677, Springer-Verlag (06).

[2] S. Huang et al., Journal of the American Chemical Society 125, 5636 (2003).

[3] X. Wang et al., Nano Lett. 9, 3137 (2009).

[4] R. Arenal, et al., J. Phys. Chem C116, 140103 (2012).

[5] R. Arenal et al., Appl. Phys. Lett. 89, 073104 (2006).

[6] D. Levhov, T.X. Than, R. Arenal et al., Nano Lett. (2011).

[7] These works have been carried out by our collaborators: T. Michel, D. Levshov, M. Paillet and JL.Sauvajol of the Charles Coulomb Lab., Montpellier U. (France).

[8] Some of these works have been developed at the Electron Microscopy Center of Argonne Nat. Lab.(US).



547
Desalination performance related to the pore-structure of activated carbon fiber by capacitive deionization
Jiyoung Kima, Seongyop Lima, Seong-Ho Yoonb, Doo-Hwan Junga,*
a Advanced Energy Technology, University of Science and Technology (UST), Daejeon 305-333 Korea
b Institute for Materials Chemistry and Engineering, Kyushu University, Fukuoka, 816-8580, Japan

Desalination performances of activated carbon fiber (OG-series; 7A, 10A, 15A, 20A from Osaka gas Co. Ltd. Japan), which had well-defined pore structure, was examined using capacitive de-ionization (CDI) method. The experiments were conducted with different concentration and feed rates of sodium-chloride solution. To evaluate the performance about each ion, the activated carbon electrodes were applied at positive or negative side of cell respectively with high performance reference carbon. The relations between the pore-structure of activated carbons and adsorption/desorption of ions from sodium-chloride solution are presented based on the experiment results.



549
In-situ keV-ion Irradiation Studies on Single-Walled Carbon and Boron Nitride Nanotubes
Raul Arenala,*, Amelia C.Y. Liub
a LMA-INA, Universidad de Zaragoza, Spain
b Monash U., Melbourne, Australia

An important aspect to consider in nanotechnology, in particular when seeking applications for nanomaterials, is their performance and behaviour against irradiation. Furthermore, irradiation is a very useful tool for materials processing, for instance, for the fabrication and modification of nanostructures. Thus, developing an understanding of the fundamental processes involved in the irradiation phenomena is a critical and highly significant issue. In this communication, we will present in-situ transmission electron microscopy (TEM) ion irradiation experiments that we have conducted on single-walled carbon nanotubes (SWCNT) and SW boron nitride nanotubes (SWBNNT). These experiments have been coupled with ex-situ Raman experiments on the same samples and in the same areas as the in-situ irradiation and TEM observations. These measurements are the first in-situ observations that have been performed on single-walled boron nitride nanotubes [1-3] and provide very rich information on these nanomaterials, potentially useful for applications in nuclear and space environments.

The in-situ ion irradiation experiments were conducted at the IVEM-Tandem facility in the Electron Microscopy Centre at Argonne National Laboratory. SWCNT and SWBNNT were irradiated with 30 keV Kr+ ions (1.25e10 ions/cm2/sec) to doses of up to 1e15 ions/cm2. The accelerating voltage of the microscope was chosen as 100 kV to limit knock-on damage from the electron beam. In parallel, we carried out ex-situ Raman experiments at different wavelengths in the visible (514 nm) and UV (244 nm) spectral ranges.

In the low ion dose regime no structural changes have been observed. In one of the explored areas, we observed the scission of a SWBNNT likely due to a single displacement cascade. Concerning the higher doses regime, the irradiation effects are evident: the modification of the NT walls, showing clear diameter shrinkage, and eventual sputtering away when the dose became very high are observed. Similar behaviours have been also reported on SWCNT. The structural modifications due to irradiation are also clearly evident from the analysis of the ex-situ Raman spectra recorded on selected regions. The observed behaviours can be explained by different irradiation phenomena, such as atomic re-arrangements and defect accumulation leading to many vacancy-cluster and Stone-Walls defects, amorphization, ion beam welding and diameter shrinkage [4,5].

To sum up, these experiments show that these two kinds of NT appear to be very resistant to high-radiation doses, suggesting that these nanomaterials could be applied as effective radiation shielding or used in devices in space environments.

References

[1] A.C.Y. Liu, R. Arenal, G. Montagnac, submitted (2013).

[2] R. Arenal, X. Blase, A. Loiseau, Advances in Physics 59, 101 (2010).

[3] P. Ayala, R. Arenal, A. Loiseau, A. Rubio, T. Pichler, Rev. Mod. Phys. (2010).

[4] A. Krasheninnikov, F. Banhart. Nature Materials, 6, 723, (2007)

[5] A. Krasheninnikov, K. Nordlund, M. Sirvio, E. Salonen, J. Keinonen. Phys. Rev. B 63 (2001)

[6] We thank P. Baldo and E. Ryan for their assistance in the in-situ ion irradiating TEM measurements. Raman spectroscopy measurements have been carried out at the ENS-Lyon (France). We acknowledge G. Montagnac for his assistance in these experiments.



550
Braiding Effects of Carbon Fibers Fabric Treated by Air DBD on Shear Resistance of Polymeric Composites
Alberto Santosa,*, Dielly Cavalcantib, Konstantin Kostova, Edson Botelhoa, Leide Lili da Silvab, et al.
a Faculty of Engineering, FEG/UNESP, Guaratingueta - SP, Brazil
b Technological Faculty of Pindamonhangaba, Pindamonhangaba – SP, Brazil

Fiber-reinforced composites are high-performance engineering materials widely applied in aerospace, marine and automobile industries due mainly to their favourable properties, such as, low specific weight, high resistances to corrosion and erosion, enhanced toughness, excellent fire resistance and high mechanical strength. In the last decades carbon fibers (CFs) reinforcements have been extensively employed to improve the mechanical properties of polymer composites.

In this work has been investigated the effect of different carbon fiber fabrics on the CF/Polyphenylene (PP) interface laminates. Two different styles of fabrics were investigated: 1x1 (plain weave) and 2x2 (twill weave) and prior the composite manufacturing the fabrics were treated with plasma. Atmospheric pressure plasma treatment for adhesion improvement of material is an attractive surface modification technique due mainly to its applicability to a variety of substrates, easy scaling-up, quick processing time and low equipment cost. In this work dielectric barrier discharge (DBD) treatment is aimed to enhance the adhesion between the composite layers without decreasing the carbon fiber mechanical resistance. The surface modification of CFs is originated by introduction of chemical functional groups and also by alteration of the surface morphology during the treatment.

The DBD reactor used in this work consists of two planar circular stainless-steel electrodes covered by 2-mm-thick glass plates. The air gap between both dielectric layers was 4 mm. The bottom electrode was connected to a high-voltage transformer (Vrms 110/20000), powered by an autotransformer Variac operating at frequency of 60 Hz. The upper reactor electrode was grounded. The DBD is constituted of large number of filamentary discharges randomly distributed over entire dielectric. The discharge power was set to 6.6 W and the CF substrates of 7.0 cm x 7.0 cm were placed on the glass layer covering the bottom electrode. The treatment times were set at 2, 5, and 10 minutes while the voltage peak-to-peak amplitude was kept fixed at 35 kV. Carbon fiber-reinforced polypropylene (CF/PP) composites were produced by hot compression moulding process. This procedure resulted in composite laminates with a thickness of approximately 2.5 mm.

The Raman spectra of all CF samples presented the characteristic D and G bands at approximately 1373 and 1595 cm-1, respectively. This observation suggests that the DBD process did not change the structure of the samples as inferred by other authors. SEM results of the treated samples revealed small particles distributed over entire surface of the fibers. These particles are product of the fibers surface etching during the DBD treatment that removes the epoxy layer covering as-received samples. AFM analysis showed that the plasma treatment changed the CF surface morphology leading to rougher fiber surface. For some treatments the rms roughness increased up to 2.1 times in comparison to the roughness of the untreated CF. Interlaminar shear strength (ILSS) test of CF/PP composites showed that for both braiding fabrics the DBD treatment increased the shear resistance of the polymeric composite.



551
Obtaining of nanosized carbon fibers with pulsed electrospinning method
Bakhytzhan Lesbayev, Zulkhair Mansurov, Gauhar Smagulova, Gaukhar Ustaeva, et al.
Institute of Combustion Problems

Electrospinning is a well known method used to obtain a universal micro- and nanosized fibers. Despite the fact that the method of electrospinning is a complex process that depends on a number of technical parameters of the installation and the raw materials used, it is possible to synthesize a wide range of carbon fiber with a complex structure. The main advantage of the electrospinning method is the possibility to obtain of continuous fibers, but for many processes especially when creating composite materials the length of the fibers is an important parameter. In present paper the studies of obtaining of fibers with the method of pulse electrospinning were carried out, and this method allows to regulate the sizes of the fibers not only in diameter, but by the length up to obtaining of nanopowder materials. The method consists in the fact that the organization of electrospinning uses high voltage pulse charge, which allows discrete break off the process of stretching of fibers. Designed laboratory setup allows to study the processes of formation of nanofibers and nanopowders under varying of the following parameters of voltage - frequency from 0.1 Hz to 1000 Hz, duty cycle from 5% to 99%, and the voltage from 9 to 18 kV. The main advantage of this method is that the variation of the above parameters allows to obtain one-dimensional fiber of a given length as well as nanopowders. The original material used is polymethylmethacrylate dissolved in dichloroethane. In order to change the structure and improve the strength properties various alloying elements of the metal salts were added to solution (cobalt chloride 6 – aquatic, aluminum chloride 6 – aquatic, and sodium carbonate). As result, prototypes of carbon fibers with stable reproducible sizes were obtained and with scanning and atomic force microscopy the structural characteristics of these prototypes were studied. Currently, studies on application of obtained materials for producing composite materials, nano-concrete and increasing of power output of solar cells are carrying out.



552
THE COMBUSTION SYNTHESIS OF CARBON NANOMATERIALS
Zulkhair Mansurov
Institute of Combustion Problems

The kinetic mechanism of conversion of hydrocarbon fuels with the formation of soot and fullerenes and graphenes are refined in strictly connection with new experimental data on the formation of fullerens and graphenes in flames. It is shown that at low pressures, the formation of fullerenes is sensitive to the spatial orientation of polycyclic aromatic hydrocarbons (PAH) molecules. The evolution of hydrocarbon fuels to polycyclic aromatic hydrocarbons (PCAH) during combustion of fuel rich flames leads to the formation of soot, and PCAHs are nuclei of soot particles. It is evident that PCAHs can be converted to soot or fullerenes, depending on combustion conditions, among which the determining parameter is pressure. It is known that the formation and synthesis of fullerenes in the traditional method of arc evaporation of graphite is performed at pressures p < 40 torr [1]. Because fullerenes are formed at low pressures, the corresponding spatial orientation is important, which requires a consideration of the steric factor. There are various models of formation of fullerenes C60, one of which is the zip mechanism [2]. A necessary condition for this mechanism is low pressure. As the pressure increases, i.e., with transition to atmospheric pressure or above, where triple collisions dominate, PCAHs coagulate to form soot clusters.

The results of research the synthesis graphene are presented is in mixture premixed propane – oxygen flames the addition of argon at atmospheric conditions. It is established that temperature of 900-950 ° C and exposition time five minutes are sufficient for synthesis of graphene films on a nickel substrate which is preferable in comparison with copper. It is defined that the zone of formation of graphene layers is on the border before the formation of soot particles.

Earlier, H. Bockhorn [3] was proposed a general scheme reaction soot formation in a homogeneous mixture of premixed flames, where intermediate products are polycyclic aromatic hydrocarbons (PAH). PAH are able to considered, as the basis of graphene formation in flames, as precursors of the formation of soot particles. The scheme of the formation of soot particles, completed by stages of the formation of fullerens and graphenes is proposed.

REFERENCES

1. Z. A. Mansurov. Producing Nanomaterials in Combustion // Combustion, Explosion, and Shock Waves. Vol. 48, № 5, P. 561–569, 2012.

2. J. Ahrens, M. Bachmann, Th. Baum, J. Griesheimer, R. Kovacs, P. WeilmЁunster, K.-H. Homann, “Fullerenes and Their Ions in Hydrocarbon Flames,” Int. J. Mass Spectrom. Ion Proc. 138, P. 133–148, 1994.

3. H. Bockhorn (ed). Soot Formation in Combustion. Springer, Berlin / Heidelberg P. 596, 1994.



554
The effect of hot stretching on the microstructure and mechanical properties of PAN and rayon based carbon fibers
Yonggen Lua,*, Hao Xiaoa, Xin Zhanga, Changling Yanga, Qingfang Zhab
a Donghua University
b China University of Petroleum

The influence of hot stretching stress, ranging from 15 to 270 MPa at four degrees of heat treatment temperature on the structure and mechanical properties of polyacrylonitrile(PAN) and rayon based carbon fibers was studied.

It was observed that the Young’s modulus increased with increasing hot stretching stress while the tensile strength increased within an appropriate range of stress and decreased with further hot stretching for the PAN based carbon fiber. However, both the Young’s modulus and the tensile strength increased with hot stress for the rayon based carbon fiber. When the PAN carbon fiber was treated at 2700 oC for a fixed time of 2.0 min under different stresses, the tensile strength of the derived carbon fiber treated under 165 MPa increased to 3.79 GPa from 3.43 GPa of that under 15 MPa, with a 10.5% increase, and then dropped to 3.37 GPa of that under 240 MPa. The same situation can be found for treatment at 2300 and 2500 oC. However, when the rayon carbon fiber was treated at 2700 ℃ for a fixed time of 2.0 min under different stresses, the tensile strength of the derived carbon fiber treated under 252 MPa increased to 1.75 GPa from 1.01 GPa of that under 36 MPa, with a 73.3% increase, while the Young’s modulus of carbon fiber increased from 62.72GPa to 161.95GPa. with a 158.2% increase. And the higher the temperature, the faster the mechanical properties increased. Wide x-ray diffraction shows that the crystallite sizes and the orientation degree of graphene planes increased of the carbon fibers heat treated with increasing hot stretching stresses. And the microvoid sizes increased with the increasing hot stretching stress. It is believed that the orientation degree of graphene planes plays the dominated factor within appropriate stretching stresses thus the tensile strength of carbon fibers increased, and then the affect of microvoids become remarkable under further hot stretching. The increased Young’s modulus of carbon fibers was mainly determined by the increased crystallite sizes and the degree of orientation of graphene planes.



555
The mechanism of forming of carbon at pyrolysis of hydrocarbons on ferromagnetic catalysts
Makhmut Biisenbayev, Zulrhair Mansurov, Shalpan Tuleibayeva
Institute of Combustion Problems

A number of researches are devoted laws and the mechanism of formation and growth of carbon threads.

However not all data established in experiments by training and to growth nanotubes, can be explained within the limits of offered mechanisms.

For example:

· The range of diameters нанотрубок is limited in limits ~ 0,7 - 100 nanometers

· The catalysts applied at cultivation carbon нанотрубок, it is exclusive metals of a subgroup of iron or their alloys

· There is no clearness why tubes, instead of continuous fibers grow.

We want to offer and prove the mechanism of growth of the carbon tubes, not entering into the contradiction with the experimental facts.

If to assume that forming carbon нанотрубки occurs under the influence of a high-tension magnetic field that all the above-stated data find an explanation. In such assumption results that fact that all above-stated metals-catalysts are ферромагнетиками, and their active particles have the sizes not allowing containing more than one magnetic domain [4].

Power lines of a magnetic field of a one-domain particle do not become isolated in a particle, and form an external magnetic field. Such particle represents a magnetic dipole.

Proceeding from this data carbon нанотрубки it is possible to explain forming by influence of a magnetic field of ferromagnetic particles.

In a question on possibility of influence of magnetic fields on chemical reactions, skepticism dominates. Computation of change of function of energy of Gibbs for system to which the magnetic field is applied, shows that the substance with a magnetic susceptibility of size of an order 10-4 (typical for diamagnetic materials) changes energy of system on 5x10-4 joule/mol in a magnetic field in size 106 А/м. This size is too small.

Let's try to estimate intensity of a field in domains ферромагнетика. It is known that ferromagnetic orderliness collapses in a point of Kjuri, i.e. for iron, approximately, at 1000К. Having counted up energy of thermal fluctuations in system at this temperature - we will receive:

kT = 1.38.10-23*1000 K = 1.38 10-20Дж

Corresponding to it on energy intensity of a magnetic field is equal:

H = U / M = 1.38. 10-20 / 9.3.10-24 = 1.48 109A/m

In the literature the order of size 1010 A/m that 10 times a necessary minimum [] is resulted.

Thus, in a domain particle and in immediate proximity from it magnetic fields of enormous intensity act. Such fields can make essential impact on a course of chemical reactions at temperatures to 1000К.



556
Calculation of Technological Parameters of new technological technique of the differential magnetron sputtering for Synthesis SiC Films
Batyr Mansurov, A. Tolegen, B.S. Medyanova, Y.S. Merkibayev, A.K. Kenzhegulov, et al.
al-Farabi Kazakh National University

The significant efforts devoted to synthesis of silicon carbides were motivated by the unique combination of properties of this material such as relatively high electron mobility, high magnitude of breakdown electric field intensity in combination with sufficiently high band gap energy and excellent thermo-mechanical characteristics compared with other polytypes. They give chance to produce electronic devices, both in discrete and integrate forms, with the highest speed and power, with a huge working temperature range, with a high element density, and with increased mechanical strength and reliability. However realization of high potential opportunities of this material is hindered by absence of qualitative heteroepitaxial silicon carbide layers. Most studies of 3C-SiC films on Si have been focused on films grown by CVD at substrate temperatures higher than 1200°C using silane and hydrocarbon (most commonly propane) as reactive gases. Such films have a rough SiC/Si interface, sometimes with a high density of voids, and a high concentration of lattice defects. These problems are related to the high growth temperature, thus the development of a low temperature process to prepare SiC films to essential for the practical application f SiC.

Efforts for reducing the growth temperature commonly involve the use of plasma to reduced pressures, e.g. plasma-assisted CVD, plasma-assisted gas-source molecular-beam epitaxy, or sputtering. The predominant research on low-pressure and low-temperature growth for 3C-SiC films has concerned the use of MBE where both the solid sources of Si and C have been used, or GS-MBE where a hydrocarbon gas is used as the C source, with either solid or gaseous Si sources.

Silicon carbide films obtained by these techniques are used as heat sinks and hard surfaces, but they are not good enough for microelectronics because of their structure imperfection.

Therefore searching of systems in which the rate of the backwards process would be noticeably and in addition would allow correcting growth defects during growth processes, is the most urgent problem that solution will determine further development of silicon carbide synthesis technology as a whole.

On the basis of estimated theoretical calculations the new technological technique of the differential magnetron sputtering which is based on balancing of streams of carbon from two magnetrons has been developed and designed. Using the symmetric two magnetron systems allows artificially reduce super saturation, due to balancing growing and etching rates of SiC films.

For definition of optimum modes for silicon carbide films growth the following calculations have been carried out. Dependence sputtering coefficient from a voltage the target-anode and dependence of deposition rates film from a current intensity and the applied voltage for silicon and graphite had been calculated.

The deposition profiles for each disk of combined silicon-carbon targets were calculated by the ratio. And it was found that the radius of silicon and graphite disks. Also the dependence of film-thickness for combined silicon-carbide target from a current intensity and a deposition time was obtained.



557
Influence of graphite characteristics on their electrochemical performance in the electrolytes used for Li-ion capacitors
Camelia Matei Ghimbeua,*, Céline Decauxb, Patrice Brendera, Mouad Dhabic, Encarnacion Raymundo-Piñerob, et al.
a Institut de Science des Matériaux de Mulhouse, CNRS LRC 7228, Mulhouse, France
b Centre de Recherche sur la Matière Divisée, CNRS-Université, Orleans, France
c Université François-Rabelais, PCMB (PCM2E), Tours, France

Hybrid capacitors combining a lithium-ion battery type (graphite, metal oxides…) and an electrical double-layer (EDL) type electrode (porous carbon) appear as very promising energy storage devices. We recently showed [1,2] the successful design of a LIC hybrid capacitor with graphite and activated carbon as negative and positive electrodes, respectively, and without supplementary lithium auxiliary electrode, as the graphite electrode is preloaded from the Li-ion based electrolyte. The performance of such system depends on the choice of the graphite and of the electrolyte. The electrolyte previously identified for the hybrid LIC capacitor [2], i.e., LiTFSI (lithium bis(trifluoromethane sulfonyl) imide) is more stable and it can provide better performances than LiPF6(lithium hexafluorophosphate) in a large temperature range [3]. However, the corrosion of Al collector was observed in the presence of LiTFSI but this drawback was overcomed by adding a few percentage of LiPF6 (1%) in the electrolyte [3].

In this work we present the influence of graphite characteristics (morphology, structure, textural properties and surface functionnality and active surface area (ASA)) on the electrochemical performance (reversible and irreversible capacity, SEI formation at different charging rates, cycle ability) in LiTFSI electrolyte and its mixtures with LiPF6 .

Two families of graphites from two companies (Timcal and Superior Graphite) were selected for this study. The graphites present distinct physical and chemical properties as revealed by several characterisation techniques (SEM, XRD, N2 adsorption, Temperature Programmed Desorption (TPD-MS)) which were correlated to the electrochemical performance. A special attention has been payed to the influence of the graphite active sites (ASA) on the SEI formation and the irreversible capacity since we previously showed that the ASA parameter is one of the most important governing the first cycle of Li-insertion for a system working in LiPF6 [4]. In the LiTFSI electrolyte, the irreversible capacity increases as the ASA and the specific surface area (SBET) increase and the graphite particles size decreases. We also pointed out that the current rate plays an important role in the SEI formation as shown by SEM and XPS analysis.

[1] V. Khomenko, E. Raymundo-Piñero, F. Béguin, High-energy density graphite/AC capacitor in organic electrolyte, J. Power Sources (2008) 643-51.

[2] C. Decaux, G. Lota, E. Raymundo-Piñero, E. Frackowiak, F. Béguin, Electrochemical performance of a hybrid lithium-ion capacitor with graphite anode preloded from lithiumbis(trifluoromethene)sulfonimide-based electrolyte, Electrochim. Acta 86 (2012) 282-286

[3] M . Dahbi, F. Ghamouss, F. Tran-Van, D. Lemordant, M. Anouti, Comparative study of EC/DMC LITFSI and LiPF6 electrolytes for electrochemical storage, J. Power Sources 196 (2011) 9743-9750

[4] Ph. Bernardo, J. Dentzer, R. Gadiou, W. Markle, D. Goers, P. Novak, M.E. Spahr, C. Vix-Guterl,Influence of graphite surface properties on the first electrochemical lithium intercalation, Carbon 49 (2011) 4867-4876



558
Cost analysis of a granular activated carbon plant design based on RSSCT: a case study for reuse of wastewater in a Brazilian petroleum refinery
Sílvia Toumaa,*, Ana Claudia Cerqueirab, Vania Santiagoa, Lidia Yokoyamac, Fabiana Araujoc
a PETROBRAS - Petróleo Brasileiro S.A.
b TRANSPETRO - Petrobras Transporte S.A.
c UFRJ - Universidade Federal do Rio de Janeiro / Escola de Química

Granular activated carbon (GAC) has been widely used in the environmental field all over the world, also finding applications in industry in various liquid and gas phase adsorptions. When it comes to industrial wastewater treatment, GAC is normally used to meet stringent regulations before discharge into receiving waters. However, as a consequence of rising concerns about pollution control together with increasing water scarcity scenario, the opportunities for reuse applications seems to be a way to keep business sustainability. Using GAC as a tertiary treatment step to remove various organic species previously to a desalination step for reuse can be quite expensive, especially in Brazil, where there are no GAC reactivation plants, neither on-site nor off-site. Thus, it is important to have a proper design of full-scale adsorbers, which typically includes time-consuming and expensive pilot-scale studies. Rapid Small Scale Column Tests (RSSCT) can be a very attractive alternative to it, since it reduces time and cost of a full-scale design. In this study, a RSSCT with 10 mm diameter column and 60 to 80 mesh GAC was applied to simulate a 15-minute empty-bed contact time (EBCT) full-scale adsorber treating a Brazilian petroleum refinery secondary wastewater, previously clarified and filtered. Removal of dissolved organic carbon was monitored either by TOC and UV absorbance analysis. As a result of the test, effluent concentration versus bed volumes fed was plotted, giving the breakthrough profile curve. Assuming that perfect similarity is maintained, the RSSCT have identical breakthrough profiles as the full-scale process. Based on this curve and other design parameters it was possible to make a cost analysis of the GAC plant, including capital and operational costs for a 20-year life cycle. The best process configuration was determined, considering beds in series and/or in parallel. This means determining the optimum number of adsorbers in order to keep the TOC specification at effluent stream with reduced frequency of bed replacement and increased carbon usage efficiency. For parallel configuration, vessel sizes and number of vessels were determined based on a wastewater flow rate to be treated of 500 m³/h together with information provided by local equipment vendors for various vessels sizes, resulting in an estimated cost of about 97 million dollars for a 20 year period. In this case, carbon bed replacement would occur every 24 days. Then, an analysis was conducted to determine the potential impact of setting up the GAC treatment system in a series configuration, which leaded to an estimated replacement in every 36 days as a result of more complete exhaustion of the adsorptive capacity of the lead vessel. Estimated times for payback appeared to be quite short even for marginal increases in GAC usage efficiencies, ranging from 1 to 5 years. Cost savings for a 20-year life cycle varied from about 7 to 30 million dollars, depending on the percentage of increase in GAC usage efficiency. Therefore, the estimated improved efficiency from series configuration seems to be quite significant, what justifies the additional investment.



559
The effect of γ-ray irradiation of polyacrylonitrile fibers on oxidation and carbonization processes
Weizhe Zhao, Jiaqiang Ji, Yonggen Lu
College of Materials Science and Engineering, Donghua University

This paper studied the effects of γ-ray irradiation on behaviors of oxidation and carbonization of polyacrylonitrile fibers. Through oxidation at different constant loads and for different time with constant length, it is found that γ-ray irradiation made PAN molecules crosslinked, which allowed a larger tension applied on the fiber tow during oxidation and made the fiber tows contracte or elongate more, and that γ-ray irradiation made the PAN molecules cyclized and oxidized initially, which shortened the stabilization time and allowed the fibers oxidized a little faster. After carbonization in batch with a fixed length, the carbon fibers through γ-ray irradiation formed a more compacted structure with higher preferred orientation of graphitic layers, which benefited the improvement of tensile strength and modulus. The strength of carbon fiber was maximumly increased about 16%.



560
Electrode Materials based on Chemically Activated Carbons from Vegetable Waste for Application in Lithium/Sulfur Batteries
Jakpar Jandosova,*, Renat Tussupbayevb, Alzhan Baimenovc, Zhumabay Bakenovb, Zulkhair Mansurova, et al.
a Institute of Combustion Problems, Almaty, Kazakhstan
b Nazarbayev University, Astana, Kazakhstan
c Kazakh National University,Institute of Combustion Problems, Almaty, Kazakhstan

Highly porous carbons, namely CRH-P-500 and CAS-P-500, were obtained from renewable materials, e.g.: vegetable wastes such as rice husk (RH) and apricot stones (AS), via H3PO4-activation for 2 and 1 hour respectively, in self-generated atmosphere at 500 ºC and H3PO4/precursor (wt/wt) impregnation ratio of 2:1. In the case of RH, upon carbonization, an additional method of desilication with 0.5M NaOH solution was applied to remove silica ash.

The activated carbons were characterized by means of modern physico-chemicals methods of investigation. Elemental analyses of both samples using X-ray fluorescence spectroscopy and VARIO ELEMENTAR III elemental analyzer detected up to 1% of remained phosphorus and about 88% of carbon. SEM characterization and nitrogen adsorption data revealed that highly porous materials were obtained. According to BET-method and BJH calculation scheme, N2 BET‑surface area and pore volume for CAS-P500 reached the values of 2030 m2/g and 1.64 cm3/g, while for CRH‑P‑500: 1690 m2/g and 1.95 cm3/g respectively. Methylene Blue adsorption data at equilibrium conditions fitted linearized Langmur model equation with high correlation coefficients, which allowed determining monolayer capacity: 562 mg/g for CRH‑P‑500 and 893 mg/g for CAS‑P‑500. These carbons were used as components in carbon-sulfur composite preparation serving as cathode in carbon-sulfur batteries.

These carbons were used for preparation of carbon/sulfur (C/S) composites applied as cathodes in lithium/sulfur (Li/S) batteries. The C/S cathode is considered as one of the most promising candidates due to its low cost, environmental friendliness and large theoretical capacity up to 1672 mAh g-1. The impregnation of sulfur into conductive highly porous carbon significantly increases electronic conductivity of naturally insulating sulfur. Moreover, excellent adsorption properties of carbon synthesized from vegetable wastes are used to trap the spare discharge products such as polysulfides. Reduction of spare products results in improved electrochemical characteristics of battery such as cyclability and rate capability.



561
Dispersibility of surface-oxidized single-walled carbon nanotubes and its influence on the performance of transparent conductive films
Sae Jin Sung, Taehoon Kim, Jun Young Oh, Chong Rae Park
Carbon Nanomaterials Design Laboratory, Global Research Laboratory, Research Institute of Advanced Materials, and Department of Materials Science and Engineering, Seoul National University

Single-walled carbon nanotubes (SWCNTs) are promising materials in electronics due to their excellent electrical conductivity from sp2-conjugated system, extremely large aspect ratio and possibility of solution process. Because indium tin oxide (ITO) which is commercial source of transparent electrode has a high price and shows a brittle behavior, SWCNT is a candidate material for the replacement of ITO. Due to the π-conjugated surface of SWCNTs, there is an aggregation among SWCNTs. Bundling of SWCNTs impedes formation of effective pathways, thus performance of SWCNT networks becomes poor. From above explanation, the degree of dispersion is critical for enhancement in electrical conductivity of SWCNT network. However, current researches related with transparent conductive SWCNT films have focused on fabrications using dispersion agents only. Surface oxidiation enables SWCNT dispersed in various solvents, but it has been known that oxidized SWCNTs are not appropriate for the application to transparent electrodes. Despite of this problem, results were reported that partially oxidized SWCNT have an potential to the transparent conductive films. To explain this phenomena, relationship between dispersibility of oxidized SWCNTs in solvent and performance of transparent conductive films is needed.

Here, we discuss the correlation between the degree of dispersion of acid-modified SWCNT suspensions and the performance of transparent SWCNT films. We find that the degree of dispersion is a key factor for the performance of transparent conductive films. Surface oxidation using an mixture of sulfuric acid and nitric acid is a more effective method for the formation of high performance films than a protocol using nitric acid only. As the dispersibility increased at the initial state, conductivity of films were enhanced due to the formation of dense networks with smaller SWCNT bundles. Our experiment displays that surface oxidation can be an alternative method for the application to transparent conductive electrodes.



563
An alternate construction approach for large-scale atomistic representations of carbon with controls over structural diversity and orientation
Jonathan Mathews, Enette Louw, Justin Watson
The Pennsylvania State University

One of the challenges associated with the construction of large-scale atomistic models of complex carbon structure is scale. While increased scale (number of atoms) has the benefits of better capturing the chemical and physical arrangement it is associated with additional challenge in capturing the structural diversity (such as stacking height and width of crystallites). Also, for many carbon structures and their precursors, there is diversity in orientations over various scales and domains. For these complex structures the traditional construction approaches are often computationally expensive, and limited in their ability to control or even determine the structural diversity. An improved approach is proposed.

Earlier work utilized image analysis for the direct determination of structural diversity of the aromatic structure from HRTEM lattice micrographs. Diversity in structure and orientation were often observed. A Perl script (Fringe3D) was created to directly reproduce molecular slice models from the lattice based on a central assumption that the fringes were as deep as they were wide. Structures produced were often 100’s of angstroms in height and width but only tens of angstroms in depth for carbon-rich structures of limited crystallinity. Thus while the structural diversity was observed with good agreement with the pair distribution function the physical structure was not considered and the models generated were of limited use. Here we increase the ability to inexpensively create improved structural models by adding an additional capability: the construction of large-scale models by first producing the desired distribution of crystallites (with control over the distribution of width, height and orientation) using Fringe3D. An additional Perl program Vol3D was written to determine the volume of the crystallites and distribute them in a more realistic representation with control over the height, width, and depth of the rectangular cuboid volume. Creation of very large-structures (100,000 atoms) for this approach is measured in minuets for a desktop computer.

By directly providing the structural diversity the iterative approach commonly utilized is avoided, and similarly distribution of pore sizes (and orientations if appropriate) can be dispersed through the structure. Construction of much larger structures is also possible. Minimization of the structure and perhaps densification (that does incur limited computational expense) produces the final representations. This is considered an improved approach for atomistic construction for those structures that are not amorphous or highly crystalline.



565
High-density Fe3-xO4 or cobalt nanoparticles filled into multiwalled carbon nanotubes
Dominique Begina,*, Walid Baaziza, Xiao Jie Liua, Cuong Pham Huua, Sylvie Begin-Colinb, et al.
a ICPEES - CNRS - Strasbourg University
b IPCMS - CNRS - Strasbourg University

The development of a new liquid-phase filling of carbon nanotubes (CNT) channel with magnetic iron oxide or cobalt-based nanoparticles (NPs) of uniform size and shape along with an extremely high loading is reported. Multiwalled CNT synthesized by CCVD were used as a starting material for the filling NPs obtained from iron and cobalt stearate salts. The surface concentration of oxygen species on the CNT surface has a great influence on the filling density and has been measured as a function of the annealing temperature determined by in situ XPS analyses. The nature of the NPs grown in the presence of CNTs was checked by XRD. In the case of the cobalt, the results show that without CNT, the decomposition yield of cobalt stearate into cobalt-based NPs is low whereas CNTS are highly charged in cobalt NPs. The representative STEM and EELS line scan confirms the relatively high Co:O atomic ratio of the encapsulated Co NPs (see below), which indicates further that surface oxidation is relatively low on these Co NPs casted inside the CNT channel compared to those synthesized without CNTs. In the case of the iron oxide, the average particle size is 13 nm when inside the channel (see figure below) or 8 nm when outside the channel, and particles are superparamagnetic at ambient temperature. First experiments are in progress to test such new materials as anode in Li-ion batteries.

Baaziz W., Begin S., Pichon B., Florea I., Ersen O., Zafeiratos S., Barbosa R., Begin D., Pham-Huu C.Chemistry of Materials, 24 (2012) 1549-1551

Baaziz W., Florea I., Begin S., Pichon B., Uhlacq C., Ersen O., Soria-Sanchez M., Zafeiratos S., Janowska I., Begin D., Pham-Huu C. Carbon, (submitted)



566
Xanthates as a novel method of carbon nanotubes and graphene covalent functionalization
Florence Pennetreau, Béatrice Vanhorenbeke, Charles Vriamont, Olivier Riant, Sophie Hermans
Université Catholique de Louvain

Since their discovery, carbon nanotubes (CNTs) have attracted a lot of interest in different fields such as material sciences, electronics, bio-medical and catalysis. However a functionalization step in usually necessary to benefit from their potential[1,2]. More recently, graphene has emerged as a new promising form of nano-carbon because of its extraordinary properties and lower production cost. In this context, we present here a new way to covalently functionalize CNTs and graphene based on the radical grafting of xanthates.

The reaction between a xanthate (noted R1O-C=S-SR2) and CNTs was initiated by thermal decomposition of a peroxide and led to grafting of two different moieties at the CNTs surface, namely the (R1O-C=S-S) and the R2 fragments. The amount of functionalization was evaluated by XPS and elemental analysis and the covalent nature of the bond between nanotubes and xanthate proved by Raman spectroscopy and thermogravimetric analyses. At best, 1 surface carbon atom of MWNTs on 11 was functionalized. Moveover functionalized nanotubes were analyzed by TEM to confirm their integrity and by SIMS to confirm the nature of functions tethered at their surface[3].

The advantages of this method are multiple such as simplicity, adaptability and versatility. Indeed by varying the ratio between CNTs, xanthate and peroxide, it is possible to modulate the grafting yield of both (R1O-C=S-S) and R2 fragments to achieve mono- or bi-functional CNTs. Moreover by changing the R2 moiety, we can modify the type of functions present at the CNTs surface to obtain starting materials useful in different applications. Up to now, five different R2 fragments have been grafted on nanotubes: an α-chloroketone, an activated ester, a phtalimide, a NHS derivative and trifluorinated aromatic ketone. The first application developed was the formation of heterogeneous catalysts by two different pathways. First the use of a R2 of activated ester type allows reacting with an amine bearing a Ru-Pt cluster and, after thermolysis, obtaining a bimetallic nanoparticulate catalyst. Secondly by reducing the (R1O-C=S-S) moiety, it is possible to obtain CNTs functionalized with thiols which have been used as an anchor for gold nanoparticles. The presence of both clusters and gold NPs has been demonstrated by XPS and TEM.

The xanthate grafting method was then adapted from nanotubes to graphene. We succeeded in covalently grafting both the (R1O-C=S-S) and R2 moieties at the non-curved graphene surface. The functionalized materials were characterized by Raman spectroscopy, XPS, TEM, TGA and elemental analysis. It was also shown that metal-containing species could be grafted at the carbonaceous surfaces by post-functionalizing grafted moieties.

[1] S. Banerjee, T. Hemraj-Benny, S. S. Wong, Adv. Mater., 17 (2005) 17.

[2] P. Singh, S. Campidelli, S. Giordani, D. Bonifazi, A.Bianco, M. Prato, Chem. Soc.Rev., 38 (2009) 2214.

[3] B. Vanhorenbeke, C.Vriamont, F. Pennetreau, M. Devillers, O. Riant, S. Hermans, Chem. Eur. J., 19 (2013) 852-856.



568
Enzyme biosensor based on N-doped activated carbon fiber electrode prepared by thermal solid-state reaction of activated PAN fiber and urea
Ji-Hyun Kim, Yesol Kim, Dayoung Lee, Hye-Ryeon Yu, Young-Seak chungnam national university
chungnam national university

The N-doped activated carbon fiber for an enzyme-based glucose sensor was prepared by reaction of activated PAN fiber and urea. The PAN based carbon fiber was activated by KOH for improving adsorption of glucose oxidase (GOD) enzyme and introducing oxygen functional groups which were reacted with urea. The reactions were carried out various weight ratios of amounts of urea per activated PAN fiber (0.5:1, 1:1, 3:1, 5:1) and temperature (150-600 OC). The synthesized samples were characterized by X-ray photoelectron spectroscopy to analysis chemical elements composition on the surface. Glucose sensing was carried out by current voltagram and amperometric methods. The mechanism of the sensitive on enzyme activity in the electrodes of glucose sensor was modeled by enzyme kinetics using the Michaelis-Menten equation.



569
Highly atom-economic synthesis of Mn3O4/graphene hybrid composites for lithium ion batteries
feng Gaoa, jiangying Qub, zongbin Zhaob, quan Zhoub, jieshan Qiub,*, et al.
a Carbon Research Laboratory, Center for Nano Materials and Science, School of Chemical Engineering, State Key Lab of Fine Chemicals, Dalian University of Technology, Dalian 116012, China
b Carbon Research Laboratory, Center for Nano Materials and Science, School of Chemical Engineering, State Key Lab of Fine Chemicals, Dalian University of Technology, Dalian, 116012, China

We present a highly atom-economic procedure for the creation of Mn3O4/reduced graphene oxide (RGO) hybrid materials which have potential applications in lithium ion battery. Graphene oxide/manganese sulfate (GO/MnSO4) suspension from modified Hummers method was in situ converted into GO/Mn3O4 hybrid composite by air oxidation. Subsequently, RGO/Mn3O4 composite was obtained by the reduction of GO/Mn3O4 in hydrazine solution. RGO/Mn3O4 composites show a high specific capacity up to 930 mAh/g, near their theoretical capacity, with good rate capability and cycling stability, owing to the intimate interactions between the graphene substrates and the Mn3O4 nanoparticles grown atop. The approach developed in this study offer an efficent and environmental friendly technique for the large-sacle production of MnOx/graphene composites for electrochemical applications



570
Study of Raman spectroscopy and its correlation with structural and morphological properties of nanostructured amorphous carbon thin films
SAURABH DAYALa,*, SASIKUMAR Cb
a Research Scholar, MSME DEPARTMENT, MANIT, BHOPAL
b ASSISTANT PROFESSOR, MANIT, BHOPAL

The carbon nanomaterials have revolutionized the field of material science since the discovery of fullerenes C60 and carbon nano-tubes. These materials offer a wide range of useful properties such as their electronic, optical, mechanical and chemical characteristics making them very interesting materials for broad range of industry.

Raman spectroscopy is very sensitive to even a slight change in structure making it very useful tool in the characterization of carbon based nanomaterials and other forms amorphous carbon thin films. Raman spectroscopy is highly sensitive to symmetric covalent bonds with little or no natural dipole moment.In the present study the effect of self-bias on structural and morphological of nanostructured diamond-like carbon (ns-DLC) thin films is explored. These films were grown at different negative self-biases ranging from -100 V to -200 V using radio frequency (13.56 MHz) plasma enhanced chemical vapor deposition technique. The generation of nanostructured morphology at room temperature in these films is confirmed by scanning electron microscopy, whereas change in microstructure by varying the self-bias is confirmed by Raman analysis. The Raman shift clearly reveals the presence of graphite and diamond like carbon films (DLC). Further the peak characteristics: FWHM, Intensity, and position are also influenced by the phase constituents, crystal structure, crystallite size and lattice stain. The ID/IG ratio was found to have inverse relation with crystallite size of diamond like carbon.



572
Graphene oxide membrane with hierarchical structure self-assembled at liquid/air interface:high absorption and energy storage performance
Quan-Hong Yanga, Wei Lva,*, Zhengjie Lib, Baohua Lia, Feiyu Kanga
a Engineering Laboratory for Functionalized Carbon Materials,Graduate School at Shenzhen, Tsinghua University
b School of Chemical Engineering and Technology, Tianjin University

Graphene oxide membrane, which always appeared in a layered structure, is one of the most important graphene-based derivatives in macroscale. It is believed to have great potential in the fields of separation and filiation, and is also considered to be an integrated electrode to assemble membrane-like supercapacitor after reduction. However, the tightly stacked layered structure goes against the fast ion transfer when it is used as the electrode in energy storage fields. In our previous work, a series of free-standing graphene-based membranes, including graphene oxide membrane, graphene oxide/carbon nanotube hybrid membrane and graphene/polymer hybrid membrane, were prepared by a liquid/air self-assembly method. Generally, the original obtained membrane contains a lot of water and the layered structure is formed after the slow removal of water caught in the adjacent layers by the oven drying in atmosphere or vacuum environment. In this study, we used a freeze-drying method to replace the ordinary oven drying method, and obtained a membrane with a hierarchical structure due to the unique water removal process. The hierarchical structure of the membrane can be described as follows: The top of the membrane has a layered structure, the middle of the membrane has unorderly structure and the bottom of the membrane has a well vertically aligned structure, containing a lot of macropores. The membrane shows good adsorption capability and rate towards the oils and large organic molecules, while the adsorption capacity is over 4000 times larger than the mass of membrane. Due to the open surface and strong adsorption ability, it also exhibits the strong adsorption to sulfur and the formed hybrid can be used as the cathode in Li-sulfur battery. The hybrid shows a good rate performance and stable cyclic ability (no capacity fading after 130 cycles) although only large macropores exit. Furthermore, the reduced membrane can also be directly used to assemble a solid-state supercapacitor, which shows good electrochemical performance.



573
Carbide-Derived Carbon Aerogels with Ultrahigh Porosity prepared from Polycarbosilane Precursors
Martin Oschatz, Lars Borchardt, Winfried Nickel, Stefan Kaskel
Dresden University of Technology

There is a considerable interest in porous carbon materials as components for catalysis, separation/purification, gas storage, electronics, and biology/medicine. A fine-tuning of their pore structure is necessary to enhance the performance within the certain application. Carbide-derived carbons (CDCs) are a class of porous carbon materials prepared by the etching of metals or semi-metals from their carbides leading to a high amount of micropores [1]. However, in many applications hierarchical pore arrangements are of fundamental interest in order to achieve high surface areas combined with advanced mass transport properties. Recently, we have reported hard- and soft templating approaches allowing the combination of a randomly oriented CDC micropore system with a well ordered mesopore arrangement [2-3]. These ordered mesoporous CDCs (OM-CDCs) show large specific surface areas of more than 2900 m2/g and total pore volumes up to 2 cm3/g leading to outstanding gas storage capacities and high performance as electrode material in supercapacitors. Moreover, a secondary macropore system was successfully introduced into CDCs using so called High Internal Phase Emulsions (HIPEs). Resulting materials offer high specific surface areas (2300 m2/g) in combination with impressively large over-all pore volumes of more than 8 cm3/g combining nm-sized pores and macrocages with diameters in the µm range [4].Here, we report a template-free synthesis of strongly hierarchical carbide-derived carbon materials starting from polycarbosilane aerogels. The polymeric precursor gels can be prepared by a platinum-induced hydrosilylation reaction followed by drying with supercritical carbon dioxide [5]. After conversion to silicon carbide the materials can be directly subjected to high-temperature chlorine treatment for the selective extraction of silicon atoms and formation of a microporous carbon network. The typical aerogel pore structure and the monolithic appearance can be fully converted since the chlorination is known to be a conformal process. CDC aerogels exhibit specific surface areas as high as 2200 m2/g as well as total nitrogen uptakes above 5000 cm3/g. The distinct aerogel pore system leads to an extremely low density and a high total porosity. Next to adsorption and electrochemistry, these materials will be highly suitable in applications where a coupling of high specific surface area, high porosity and low density with the favorable properties of carbon such as electric conductivity, high thermal stability and high chemical inertness is required.

[1] V. Presser, M. Heon, Y. Gogotsi, Adv. Funct. Mater. 2011, 21, 810.

[2] P. Krawiec, E. Kockrick, L. Borchardt, D. Geiger, A. Corma, S. Kaskel, J. Phys. Chem. C 2009, 113, 7755.; M. Oschatz, E. Kockrick, M. Rose, L. Borchardt, N. Klein, I. Senkovska, T. Freudenberg, Y. Korenblit, G. Yushin, S. Kaskel, Carbon 2010, 48, 3987.

[3] L. Borchardt, M. Oschatz, M. Lohe, V. Presser, Y. Gogotsi, S. Kaskel, Carbon 2012, 50, 3987.

[4] M. Oschatz, L. Borchardt, M. Thommes, K. A. Cychosz, I. Senkovska, N. Klein, R. Frind, M. Leistner, V. Presser, Y. Gogotsi, S. Kaskel, Angew. Chem. Int. Ed. 2012, 51, 7577.

[5] G. D. Sorarù, F. Dalcanale, R. Campostrini, A. Gaston, Y. Blum, S. Carturan, P. R. Aravind, J. Mater. Chem. 2012, 22, 7676.



574
Development of a mini directly heated reactor to measure the gasification rate of coal char under high pressure and high temperature in the presence of CO2, H2O, CO and H2
Miura Kouichi, Makino Mitsunori, Imai Syunsuke, Shibata Yasuhiro, Sasaoka Eiji, et al.
Department of Chemical Engineering, Kyoto University

In Japan oxygen blown gasification with recycled CO2 has been proposed to facilitate the CO2 separation under the NEDO “Innovative Zero-emission Coal Gasification Power Generation Project”. The process also expects that the gasification rate of char will increase by the high pressure CO2 recycled. The latter will expected to increase the gasification efficiency. To realize the gasification concept practically, it is essential to estimate the gasification reactivity of coal chars under high pressure of 2 MPa at T < 1300°C in the presence of CO2, H2O, CO and H2. However, the direct measurement of gasification rates of coal chars under such conditions is very difficult and very few works have been performed. Direct gasification rate measurements of coal chars under high pressure have been made by several experimental techniques including thermobalance and wire mesh reactor. When using these techniques, it is very difficult to eliminate the mass transfer effects especially at high temperature and high pressure. It is also very difficult to supply H2O to the reactor of high temperature and high pressure when using small scale reactors. Using sophisticated pressurized drop tube furnace (PDTF) type reactor, H2O can be easily supplied. However, the presence of CO2, H2O, CO and H2 makes the gasification rate measurements very difficult even by using the PDTF. This is because the water-gas shift reaction that inevitably occurs changes the gas atmosphere in the course of reaction. This makes the analysis of experimental data obtained very difficult.

In this work a mini directly heated reactor (mini-DHR) was constructed to measure the gasification rate handily at T < 1300°C under the pressure of 2 MPa in the presence of CO2, H2O, CO and H2. The mini-DHR was made of U-shaped SUS or Pt tubing of 3 mm I.D. The reactor itself was used as a heating element. An electric current of 60 – 130 A and a few volts were introduced to the reactor to heat up the reactor up to 900 to 1300°C. About 0.7 mg of char particles dispersed in quarts wool was placed just above a thermocouple in the reactor. The conversion of char, X, was estimated by combusting the remaining char sample. The experimental set up enabled to use high gas velocity and hence enabled to measure the gasification rates under chemical reaction controlling conditions. The gasification rate measurements in the presence of CO2, H2O, CO and H2 were realized by supplying CO2, CO, and H2. Utilizing the water–gas shift reaction that inevitably occurs, the concentrations of CO2, H2O, CO and H2 were successfully adjusted. The X vs. t relationships obtained under various conditions were analyzed to formulate gasification rates equation for the chars prepared from an Australian brown coal and a Chinese bituminous coal.



575
Structural Varieties of Polymer-Based Carbide-Derived Carbons
Martin Oschatza,*, Lars Borchardta, Marion Adama, Soeren Thiemeb, Stefan Kaskela, et al.
a Dresden University of Technology
b Fraunhofer IWS Dresden

Metal- or semi-metal atoms can be selectively removed from their carbides in the presence of halogens such as chlorine gas at high temperatures. This etching reaction produces a highly microporous carbon network known as carbide-derived carbon (CDC) [1]. The properties of the carbon structure like micropore diameters, surface properties, and the degree of graphitization can be controlled by the halogenation conditions and the particular carbide precursor. The size distributions of CDC micropores are rather narrow as compared to other porous carbon materials, such as physically or chemically activated carbons. This makes CDCs highly suitable for applications in gas storage, separation or as electrode materials in supercapacitors. However, for certain applications like cytokine removal, filtration of gas mixtures or battery systems the generation of uniformly sized secondary meso- or macropore networks is of leading importance and is not readily accessible when starting from bulk carbides.

In the last years we reported various approaches for the generation of CDCs with hierarchical pore architectures starting from polycarbosilanes as SiC precursors to overcome this drawback. A hard templating procedure (widely known as nanocasting), was applied for the synthesis of CDC materials with an ordered mesopore system using oxidic templates (e.g. SBA-15 or KIT-6) [2]. Soft templating methods, namely the evaporation-induced self-assembly (EISA) and high internal phase emulsions (HIPEs), allowed for the synthesis of inverse mesoporous and macroporous structures, respectively [3-4].

In the present contribution we report advanced methods for the synthesis of various hierarchical CDC materials starting from synthetic, biological as well as technical templates showing the impressive flexibility of the use of polycarbosilane precursors for the synthesis of CDC structures. The resulting carbon materials have proven to show outstanding properties in applications ranging from electrical energy- and gas storage to separation processes.

For instance, nanocasting of mesocellular silica foams has been applied for the synthesis of large-mesopore carbide-derived carbons with specific surface areas up to 2800 m2/g and total pore volumes as high as 2.4 cm3/g. These materials show outstanding performance as electrode materials in electrochemical double-layer capacitors with specific capacities significantly exceeding a value of 240 F/g in aqueous electrolyte (1 M H2SO4). Furthermore, extremely high reversible capacities of more than 800 mAh/g (related to the mass of the active material) and outstanding cycling performance were determined for the large-pore CDCs when used as a cathode material in lithium-sulfur cells, which are one of the most promising future generation battery systems. Moreover, we report a novel impregnation technique for the implementation of micropores within the walls of different sorts of wood (oak, pine, birch) and cellulose acetate cigarette filters. The resulting CDCs display ideal filter materials since they combine high specific surface areas due to microporous walls with a directional mass transfer leading to advanced adsorption kinetics in combination with low pressure drops.

[1] V. Presser, M. Heon, Y. Gogotsi, Adv. Funct. Mater. 2011, 21, 810.

[2] M. Oschatz, E. Kockrick, M. Rose, L. Borchardt, N. Klein, I. Senkovska, T. Freudenberg, Y. Korenblit, G. Yushin, S. Kaskel, Carbon 2010, 48, 3987.

[3] M. Oschatz, L. Borchardt, M. Thommes, K. A. Cychosz, I. Senkovska, N. Klein, R. Frind, M. Leistner, V. Presser, Y. Gogotsi, S. Kaskel, Angew. Chem. Int. Ed. 2012, 51, 7577.

[4] L. Borchardt, M. Oschatz, M. Lohe, V. Presser, Y. Gogotsi, S. Kaskel, Carbon 2012, 50, 3987.



577
Sponge Spicules formation studies by Analytical Transmission Electron Microscopy
André Rossia,*, Andréa Carreirob, Madalena Barrosoc, Michelle Klautaud, et al.
a Universade Federal do Rio de Janeiro, Centro de Ciências da Saúde,Instituto de Ciências Biomédicas, Laboratório de Biomineralização
b bDivisão de Metrologia de Materiais, Instituto Nacional de Metrologia, Normalização e Qualidade Industrial
c Universidade Federal do Rio de Janeiro, Centro de Ciências da Saúde, Instituto de Ciências Biomédicas, Laboratório de Biomineralização
d Universidade Federal do Rio de Janeiro, Centro de Ciências da Saúde, Instituto de Biologia, Departamento de Zoologia, Laboratório de Biologia de Porifera

The objective of this work is to understand the biomineralization process of sponges and especially the role of extracellular matrix macromolecules in the control of this process.

This study was performed with analytical transmission electron microscopy on triaxon spicules from Paraleucilla magna belonging to the Calcarea class.

Macroskeleton of sponges is a three-dimensional supportive framework of mineral spicules and collagens. After complete removal of the organic part, focused ion beam of a scanning electron microscope was used for samples extraction of triaxon spicules shaped in stars. This method allowed us to choose the region and the orientation of the obtained thin cross sections. Moreover, the relative orientation of these cross sections has been conserved after welding them on the copper grid sample holders.

Selected area diffraction (SAD) was used to determinate the crystallographic characteristic of the spicules. It was shown that the spicules are monocrystalline calcite and the geometrical axis of the unpaired one is close to the <211> zone axis. No evidence of crystallographic defects has been observed by high resolution transmission electron microscopy. Calcareous spicules are impure calcite containing a solid solution of MgCO3. EDX Chemical analysis was carried out made to quantify the presence of magnesium and its atomic concentration is not homogeneous and it is less than 10%.

Voids with or without amorphous material were observed in several spicules. This observation is not general. A number of them do not present such defect.

Electrons Energy Loss Spectroscopy (EELS) was performed to characterize this amorphous material, and especially to highlight the presence of macromolecules in calcite. Special attention was given to the energy-loss near-edge structure (ELNES), which contains detailed chemical and structural information concerning the oxidation state, structural organization and molecular bonding. A comparison between the carbon K edges recorded from pure Calcite and from the spicules shows significant changes in the near-edge structures which inferred that the proteins are not particularly localized in voids. More, they are not present in all observed biogenic calcite.

From the present work and those reported by other authors (Jones 1955; Sethmann 2008) we can conclude that: i) spicules are calcite composites containing organic matter ii) the presence of organic matter does not seem to be the source of crystallographic defects and more, the biogenic calcite is close to a perfect crystal iii) there are several morphological orientations of the single crystals that constitutes the spicules versus the network of rhombohedra calcite.

Thus we can conclude that the macromolecules of the extracellular matrix do not play a major role in the growth oriented calcite single crystals constituting the spicules.

W.C. Jones (1955) Journal of Microscopical Sciences 96, 123-144

I. Sethmann, G. Wörheide (2008) Micron 39, 209-208



579
Preparation of nitrogen and boron doped carbon hollow spheres with porous shell
Noelia Alonso-Morales, Ismael Mate, Fran Heras, Miguel Angel Gilarranz, Juan Jose Rodriguez
Autonoma University of Madrid
Nitrogen and boron doped carbon hollow spheres with porous shells were synthesized by template method. The material combines the interesting morphology, of carbon hollow spheres with porous shell, with the properties of carbons doped with nitrogen or boron. Silica submicrospheres with a solid core and mesoporous shell were used as template. The template was obtained following the method proposed by Alonso-Morales et al. [1], using tetraethoxysilane (TEOS) as precursor to obtain the solid silica nuclei according to the Störber method [2]. A mixture containing TEOS and C18TMS was used to form the mesoporous shell around the solid core. A phenol-formaldehyde resin was used as carbon precursor to obtain the doped hollow spheres. Nitrogen or boron additives were added with the formaldehyde addition step, in order to insert the doping element in the carbon precursor network. Pyridine, 1-10-phenantroline, boric acid and sodium tetraphenyl borate were used as doping additives. The carbon precursor with the doping element was heated in inert atmosphere to 1123 K at rate of 5 K/min, and maintained at such temperature during 7 h to achieve complete pyrolysis. The resulting carbon aluminosilicate spheres were washed with HF (48%) to dissolve template and obtain the doped carbon hollow spheres. The doped carbon hollow spheres were analysed by elemental analysis, nitrogen adsorption/desorption at 77 K, SEM, TEM and XPS. SEM images of the doped materials prepared showed that they are composed by individual spherical carbon particles with a mean diameter around 700 nm. No changes in morphology were observed respect to the material obtained without doping agent, as observed by SEM and TEM characterization. Nitrogen doped hollow spheres obtained with phenanthroline as doping additive showed a higher nitrogen content (0.6-4.4%, w) than those obtained from pyridine (0.3-2.3%, w). XPS analysis indicated the presence of three different nitrogen species in the carbon matrix: pyridine-like, pyrrole-like, and quaternary N-bonds. The proportion of each type of bond depended on the nitrogen source and the percentage added during the synthesis. The surface area of the samples, resulting from the porosity of the sphere shell, increased with the nitrogen content of the samples with values from 1500 to 2100 m2/g. Likewise, the pore structure displaced to a lower contribution of mesoporosity, compared to the non-doped material. The boron doped hollow spheres showed doping element contents of up to 10% (w), depending on the additive and the additive concentration used. Boric acid led to higher boron contents in the final material. The doping with boron led to some loss of porosity, respect to the non-doped material, although the morphology showed no changes. References [1] N. Alonso-Morales, M.A. Gilarranz, J. Palomar, J. Lemus, F. Heras, J.J. Rodriguez. Preparation of hollow submicrocapsules with mesoporous carbon shell. Carbon 2013. [2] W. Stöber, A. Fink. Controlled Growth of Monodisperse Silica Spheres in the Micron Size Range. J Colloid Interf Sci 1968;26:62-69.


580
Surface interactions between graphene-based carbon nano-objects
Irene Suarez-Martineza, Chris P. Ewelsb, Marc Monthiouxc,*, Jagjiwan Mittalc, Hatem Allouchec, et al.
a Nanochemistry Research Institute, Department of Chemistry, Curtin University of Technology, P.O. Box U1987, Perth, WA, 6845, Australia
b Institut des Matériaux Jean Rouxel, UMR6502 CNRS, University of Nantes, 2 rue de la Houssinière, F-44322 Nantes, France
c Centre d’Elaboration des Matériaux et d’Etudes Structurales, UPR-8011 CNRS, University of Toulouse, BP 94347, F-31055 Toulouse, Cedex 4, France

Carbon nanocones (also referred to as nanohorns) and fullerenes were jointly prepared in a single batch by electric arc discharge.

Frequent, spontaneous chemi-/physi-sorption of C60 buckminsterfullerenes and carbon nanocone surface in the vicinity of the cone apexes was observed upon investigation by high resolution electron microscopy. Whether the chemi-/physi-sorption occurred was found to depend on the cone apex angle, with a threshold at 60° beyond which the sorption is no longer possible.

In order to understand the phenomena, the interaction between C60 and carbon cones with different tip angles (in relation to the number of pentagons at or close to the cone apex) was investigated theoretically by considering the physi-sorption energetics of C60 to the exterior of the horn surface. Calculations covered a range of cone angles from flat graphene, through 114°, 84°, 60°, 39° and 20° to fullerene pair interaction. Full DFT/LDA calculations were performed and the influence of dispersion forces were considered independently using a numerical potential. Fullerenes were found to bind weakly to the external nanocone wall with 0.29 nm spacing (0.5–0.9 eV binding energy), showing no discernable trend with cone tip angle. Then, covalent bridging (chemisorption) was considered. We showed that oxygen mediates covalent cross-linking between fullerenes and high angle nanocone tip outer surface (i.e., cones whose apex is formed with the presence of more than 3 pentagons), analogously to oxygen-mediated fullerene dimerisation (C120O).

The theoretical results demonstrate that oxygen bridging only occurs in systems with relatively localized double bond character, hence they explain the experimental observations. More generally, the results apply to the interaction between any graphene-based carbon nano-object surfaces.



582
Transmutation of Structure and Properties in the Preparation of Chestnut Shell Based Biochar
Qilin Wu, Guangxue Wang
Donghua University, Shanghai, China

Chestnut shell based biochar with high calorific value was manufactured through pre-oxidation and carbonization. The pyrolysis behaviors and the transmutation of both the structure and properties during the carbonization were investigated.

The pyrolysis behaviors of chestnut shell were studied by TG and GC-MS. Results showed that there are three stages of pyrolysis. With catalyst, the TG curve slightly shifted to low temperature at the same heating rate. With the pyrolysis temperature increasing, the weight proportion of CO2 in pyrolysis products increased, while furans decreased obviously. The catalyst restrained the levoglucosan's generation.

The transmutation of elements composition, functional groups and crystalline structure in pre-oxidation and carbonization were investigated by element analysis tester, FT-IR and XRD respectively. As the process temperature increased, carbon element content increased gradually and carbon network grew up.

The transmutation of calorific value was investigated by oxygen bomb calorimeter. Results showed that the carbon yield decreased as the process temperature increased, while the transformation of density was undulation. Calorific value went up slowly in pre-oxidation process, but it increased quickly in carbonization stage. With the catalyst, the chestnut shell based biochar with carbon yield of 44.31% and calorific value of 35.48MJ/Kg can be obtained at 750℃.



583
A computational study of defects and their mobility in bulk and nano-carbons
Jean-Marc Leyssale, Baptiste Farbos, Gérard Vignoles
Laboratoire des Composites ThermoStructuraux - CNRS/CEA/Herakles/Université Bordeaux1

We will present first some atomistic simulation results, based on classical molecular dynamics simulations and the Image Guided Atomistic Reconstruction (IGAR) method [1,2], on the structure of laminar pyrocarbons (pyCs) and of polycrystalline graphene (pcG) layers. This will show that the structure of pyCs essentially consists in stacks of pcG, connected together by screw dislocations [2] while the pcG can be seen as disoriented nano-sized hexagonal graphene planes bound together through grain boundaries made of networks of pentagon-heptagon pairs and holes. In a second step, we will discuss results on the formation and mobility of di-vacancies - a very low mobility defect - in graphene, in line with the structure of pcG, before presenting some results on the structural evolution (healing) of pcG under heat treatment.

[1] Leyssale, J.-M.; Da Costa, J.-P.; Germain, C.; Weisbecker, P.; Vignoles, G. L., App. Phys. Lett. 95 (2009) 231912.

[2] Leyssale, J.-M.; Da Costa, J.-P.; Germain, C.; Weisbecker, P.; Vignoles, G. L., Carbon 50 (2012) 4388-4400.



584
Elemental Analysis of different heavy oils
Fernanda Albuquerque, Luiz Castro
NCDTC - Núcleo de Competência para o Desenvolvimento de Tecnologia de Carbono / CTEx

Heavy fossil oils are very complex mixtures of hydrocarbons comprising nitrogen and sulfur compounds and metals in minor proportion. These oils may be originated or produced from petroleum sources or extracted from within rocks. Nitrogen, sufur and metals are inherent of these fossil materials however, it is known already that metals can also be introduced into petroleum derivates by the corrosion process of vases and pipes, by chemicals used to avoid it, dispersants and catalysts on refining stages.

The production of advanced carbon materials, such as pitch based carbon fibers, should take into consideration the influence of these heteroatoms into its production process and properties. Small catalyst amount left over from FCC process can also speed up undesirable reactions during the anisotropic pitch production and severely interfere in the mesophase production affecting hardly the advanced carbon materials properties.

In this work, different heavy oils from FCC process were analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) in order to determine their metals contents and by elemental analysis to determine carbon, hydrogen, nitrogen, sulfur and oxygen concentrations.



587
Preparation of Zeocarbons by exchange and impregnation of mordenite with dyes
Esmeralda García Díaz, Fernando Cortina-Moreno, María de la Paz Elizalde-González, Martín Marino Dávila-Jiménez
Universidad Autónoma de Puebla

Combinations of zeolites and carbon are under active study in the fields of catalysis, nanoscience, and carbonaceous materials. The most extensively studied materials include the zeolite-carbon composites, and the use of the zeolite as a template in the preparation of ordered micro and mesoporous carbon. However, these materials must differ from the material including carbon formed in the zeolite channels. Zeocarbons are of interest because synergistic effects are present between the zeolite and carbon. The purpose of this study was the modification of pre-activated natural (NM) and synthetic mordenites (SM) with two types of dye and its further carbonization. Impregnation was conducted with a mixture of anionic triarylmethane dyes (ABs), while ion exchange was performed with the cationic dye methylene blue (MB) at different concentrations to yield the exchange isotherm. Characterization of the zeolites, the zeocarbon precursors and the zeocarbons was carried out by X-ray fluorescence, X-ray diffraction, thermogravimetric analysis, FTIR spectroscopy and nitrogen adsorption. The theoretical cation exchange capacity of SM was 0.80 meq g-1, whereas the effective exchange capacity was 0.12 meq g-1. SM and NM exhibited an exchange capacity upon MB of 0.02 and 0.2 meq g-1, respectively. The chosen synthetic mordenite had low surface area (20 m2 g-1) in order to be comparable with the specific surface of the natural mordenite (40 m2 g-1). After exchange with MB, the BET specific surface area of the zeocarbon precursors increased considerably, reaching 300 m2 g-1 in SM and 165 m2 g-1 in NM for an exchanged amount of MB of 5 mg g-1 in SM and 67 mg g-1 in NM. The impregnated zeocarbon precursors, containing low amounts of ABs, i.e. 0.73 mg g-1 in SM and 0.87 mg g-1 in NM exhibited 77 m2 g-1 and 184 m2 g-1, respectively. High impregnation amounts (5%w) corresponding to 46 mg g-1 increased the BET specific surface of SM up to 320 m2 g-1. However, the specific surface area magnitude of the zeocarbon precursor prepared with NM containing 48 mg g-1 of ABs was 36 m2 g-1 indicating that the zeolite porosity was affected. The DRIFT spectra of the zeocarbon precursors showed the characteristic bands of the zeolites framework and of aromatic groups.



591
Preparation of size controllability spherical mesoporous carbon with magnetite nanoparticles
Toshihide Horikawa, Takuma Hasegawa, Ken-Ichiro Sotowa
Department of Advanced Materials, Institute of Technology and Science, The University of Tokushima

Magnetically separable spherical mesoporous carbon was successfully synthesized by emulsion polymerization of resorcinol-formaldehyde (RF) with Fe3O4 magnetic nanoparticles. Fe3O4 nanoparticles which were synthesized by coprecipitation of ferric and ferrous iron and have 10 nm mean diameter were embedded into the RF sol. RF spherical hydrogel particles were dried by freeze drying, and then the dried particles were carbonized at high temperature in flowing nitrogen stream. The resulting magnetite spherical mesoporous carbon was denoted as MSMC. The mesopore sizes of MSMC were controlled by changing the basic catalysis (K2CO3) amount [1], and the particle sizes of MSMC were also controlled in the range from about 10 to 500 μm by changing the apparent viscosity of the RF sol containing Fe3O4 nanoparticles accompanying the gelation to put into the cyclohexane containing a surfactant for preparation of the spherical RF hydrogels [2, 3]. We investigated the influence of the added Fe3O4 nanoparticles on the pore properties and the size controlling of MSMC. We found that the most of Fe3O4 nanoparticles were located on the surface of MSMC because the nanoparticles were self-assembled on interface between RF solution and cyclohexane due to the surfactant in cyclohexane during the spherical particles synthesis by emulsion polymerization, although the Fe3O4 nanoparticles were dispersed evenly in the bulk RF carbon without the emulsion polymerization process. As a result, we also found that the amount of surfactant in the cyclohexane for emulsion polymerization is one of the crucial factors to obtain the pore volume of MSMC as same as that of the bulk RF carbon. Since the surfactant in cyclohexane favors to adsorb on Fe3O4 nanoparticles, it covered the surface of MSMC and caulked the pores of MSMC. Therefore, there are the proper conditions of the additive amount of the surfactant in cyclohexane for maintaining the pore volume as same as the bulk RF carbons.

References

[1] Horikawa T, Hayashi J, Muroyama K. Controllability of pore characteristics of resorcinol-formaldehyde carbon aerogel. Carbon. 2004;42(8-9):1625-33.

[2] Horikawa T, Hayashi J, Muroyama K. Size control and characterization of spherical carbon aerogel particles from resorcinol–formaldehyde resin. Carbon. 2004;42(1):169-75.

[3] Horikawa T, Ono Y, Hayashi J, Muroyama K. Influence of surface-active agents on pore characteristics of the generated spherical resorcinol–formaldehyde based carbon aerogels. Carbon. 2004;42(12–13):2683-9.



592
CATALYTIC ACTIVITY OF MINERAL RESIDUES (Fe, Mn) IN THE HYDROCONVERSION OF DIBENZYLETHER FOR COAL LIQUEFACTION PROCESS
Andrés Moreno, Wilson Ruiz, Juliana Sanchez, Jennifer Laverde
Universidad de Antioquia

The gradual depletion of world petroleum reserves and the large global coal reserves have increased the interest in the direct coal liquefaction as an alternative to supply liquid fuels. Catalysts and solvents are used for direct coal liquefaction with the purpose to moderate the reaction conditions and to increase the liquid products yield. The most used catalysts are metal transition sulfides, especially, iron sulfides because of their relative high activity and the possibility to be obtained from low-priced mineral ores or industrial wastes. The principal solvents are hydroaromatic compounds which are hydrogen donor compounds.

Due to the complexity of the coal structure dibenzylether was selected as a coal related model compound to study the effect of four catalysts from different sources and tetralin as hydrogen donor solvent in the hydrogenation and hydrocracking reactions.The purpose of this work was to understand the role of catalyst and solvents and the chemical transformations that happen during the process.