TANSO
Online ISSN : 1884-5495
Print ISSN : 0371-5345
ISSN-L : 0371-5345
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Volume 2014, Issue 265
Displaying 1-10 of 10 articles from this issue
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Research Paper
  • Effects of graphite oxide additions on the oxygen reduction reaction activity of a carbon alloy catalyst for a polymer electrolyte fuel cell cathode
    Takuya Maie, Saki Tsuboi, Jun-ichi Ozaki
    Article type: Research Paper
    2014 Volume 2014 Issue 265 Pages 159-164
    Published: November 15, 2014
    Released on J-STAGE: December 15, 2014
    DOIhttps://doi.org/10.7209/tanso.2014.159
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    The effects of graphite oxide (GO) additions on the oxygen reduction reaction (ORR) activity of carbon alloy catalysts were examined in order to develop high performance cathode catalysts for polymer electrolyte fuel cell. Different amounts of GO were mixed with a carbon alloy precursor consisting of phenolic resin and phthalocyanine iron, followed by carbonization at 800 °C. Thermogravimetry revealed that the GO addition changed the carbonization behavior of the precursor. The formation of a nanoshell structure was observed under TEM for the carbons derived from precursors containing less than 50% GO. The ORR activities of the obtained carbons in 0.5 M H2SO4 varied with the GO content showing a maximum at 40% GO. A similar trend was obtained for the relation between the N/C atomic ratio determined by XPS and the GO content; the contribution of edge nitrogen species such as pyrrole/pyridone and pyridine types to the ORR activity was suggested. The results indicate that the GO addition to the carbon alloy precursors improved the ORR activity, and that it was caused by the introduction of edge nitrogen species.
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Short Paper
  • A carbonaceous thin film containing N-coordinated Fe and Co with catalytic activity for oxygen reduction
    Jun Maruyama, Tsutomu Shinagawa, Zyun Siroma, Atsushi Mineshige
    Article type: Short Paper
    2014 Volume 2014 Issue 265 Pages 165-168
    Published: November 15, 2014
    Released on J-STAGE: December 15, 2014
    DOIhttps://doi.org/10.7209/tanso.2014.165
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    Carbon materials containing Fe coordinated by N atoms (Fe-Nx moiety) embedded in the surface have been attracting much attention as noble-metal-free oxygen reduction catalysts for polymer electrolyte fuel cells. A carbonaceous thin film containing N-coordinated Fe and Co was formed from Fe and Co phthalocyanines on the basal plane of highly-oriented pyrolytic graphite to fundamentally investigate the effects of the addition of another kind of metal. An increase in the oxygen reduction current was observed for the carbonaceous thin film compared to those containing only either metal, suggesting the synergetic effect of their coexistence.
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Integrated Paper
Account
  • The effect of a graphene support on the properties of Pt electrode catalysts in fuel cells
    Junji Nakamura
    Article type: Account
    2014 Volume 2014 Issue 265 Pages 177-186
    Published: November 15, 2014
    Released on J-STAGE: December 15, 2014
    DOIhttps://doi.org/10.7209/tanso.2014.177
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    The use of graphene as a catalyst support for Pt in fuel cells is reviewed. Sub-nano Pt clusters can be prepared on graphene with an electrochemical surface area of 170 m2/g. For such small Pt clusters on graphene, significant improvements in catalytic activity have been observed for the electro-oxidation of CO or methanol, indicating that the graphene support has an effect on the properties of the Pt catalyst. The Pt clusters interact with graphene, resulting in a modification of Pt in terms of electronic structure. The interaction between Pt and graphene is ascribed to π-d hybridization. The reactivity of graphene with molecules or metal clusters is also discussed, in which we propose that non-bonding pz states are responsible for the reactivity.
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Review Papers
  • Influence of carbon deposition on the anode performance of solid oxide fuel cells
    Toshiaki Matsui, Koichi Eguchi
    Article type: Review Paper
    2014 Volume 2014 Issue 265 Pages 187-194
    Published: November 15, 2014
    Released on J-STAGE: December 15, 2014
    DOIhttps://doi.org/10.7209/tanso.2014.187
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    Solid oxide fuel cells (SOFCs) are promising power generation systems because of their high energy conversion efficiency, fuel flexibility, and low emissions. High-temperature operation of SOFCs enables the internal reforming of fuels such as hydrocarbons and alcohols in the cell chamber, which leads to the construction of a simplified generation system. In addition to the high activity for the reforming and electrochemical oxidation of fuel, the anode is required to be tolerant to the carbon deposition formed by the decomposition of hydrocarbon fuels. In this review, we focus on the degradation of the anode induced by the carbon deposition in the internal reforming operation of SOFCs. We also provided important factors to design the anode with high tolerance to carbon deposition.
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  • Recent advances in carbon electrodes for the development of enzyme-based biofuel cells
    Seiya Tsujimura
    Article type: Review Paper
    2014 Volume 2014 Issue 265 Pages 195-203
    Published: November 15, 2014
    Released on J-STAGE: December 15, 2014
    DOIhttps://doi.org/10.7209/tanso.2014.195
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    In this review, recent developments in enzymatic biofuel cell (EBFC) technology are reviewed. A general introduction to EBFCs, including their operating principles and applications, is provided. The electron transfer mechanism, mediator and enzyme materials (anode and cathode) are discussed. EBFCs are promising for sustainable green energy applications; however, they are still at an early stage of development, with many yet-to-be-resolved fundamental scientific and engineering problems. Two critical problems are short lifetime and poor power density, both of which are related to enzyme stability, electron transfer rate, and enzyme loading. To achieve the practical application of EBFCs, a promising approach is to use porous carbon materials as enzyme supports. Strategies for the design of hierarchically structured supports with both mesopores and macropores are considered. The large surface area of these mesoporous materials can increase the enzyme loading and electron transfer efficiency. The macropores enable efficient biocatalyst and fuel transport. The essential properties of the resulting materials with respect to the EBFC application are also discussed. A combination of electron transfer technology and porous carbon material would be helpful in achieving a much higher and stable current output, thus contributing to a practical advance in the sustainable energy field.
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  • Development of carbon alloy catalysts for a polymer electrolyte fuel cell
    Jun-ichi Ozaki, Yasuo Imashiro
    Article type: Review Paper
    2014 Volume 2014 Issue 265 Pages 204-212
    Published: November 15, 2014
    Released on J-STAGE: December 15, 2014
    DOIhttps://doi.org/10.7209/tanso.2014.204
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    Using hydrogen as an energy source is the most promising option to construct a society with low carbon dioxide emission. We are dreaming to establish such a world by using carbon materials to produce, store and use hydrogen. The present paper provides an explanation of the carbon alloy cathode catalysts for polymer electrolyte fuel cells, which we have discovered and nurtured to the level of platinum catalysts. The paper explains the necessity of developing non-platinum cathode catalysts and our ideas for carbon alloy cathode catalysts, to meet the demand. It then gives our research results on the active sites for oxygen reduction reaction (ORR) of the carbon alloy catalysts by comparing them with results from other researchers on non-platinum cathode catalysts. The paper concludes that the ORR active sites of our catalysts are disordered carbon structures formed on the carbon alloy catalysts. Lastly, the paper describes our efforts to improve the catalytic activity, where our latest carbon alloy catalysts with the highest cell performance are presented.
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