Study of alcohol electrooxidation mechanism at nano-particle electrocatalyst by using integrated powder microelectrodes

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Thus far, electrocatalyst investigations have consisted of two categories ; one is Pt-plate electrode-based fundamental study and the other is Pt-loading carbon-based single-cell characteristic study. The present report is planned to study alcohol electrooxidation mechanism directly at powder electrocatalysts for use in direct alcohol fuel cells (DAFCs) by employing a powder microelectrode without any influence of binder polymer. We have focused our attention on an electrocatalyst of Pt-loading carbon (Pt/C) and filled it to the microcavity of the powder microelectrode to measure the alcohol oxidation activity easily and precisely. Investigated topics are summarized as follows. Powder microelectrode filled with Pt/C or Pt-Ru/C is utilized to measure I-V curves of C_1-C_4 alcohol oxidation under elevated temperature and pressurized conditions. In addition, a dual microelectrode of powder microelectrode combined with microdisk electrode was fabricated, in which the latter collector electrode successfully detected the reaction product of alcohol oxidation at the former generator electrode. Moreover, reaction products/intermediates produced at the membrane-electrode assembly was investigated in order to clarify the reaction pathways, by developing analyzing equipment. Furthermore, electrochemical solid-state half cell was fabricated to investigate the difference of alcohol oxidation reactions between aqueous system and proton-exchange-membrane-based solid system. In conclusion, by designing new electrode system to evaluate the functional materials used in the DMFCs, electrochemical studies for the powder electrocatalysts and the electrocatalyst-based cell systems have been greatly improved.