Porous-microelectrode study on Pt/C catalysts for methanol electrooxidation |
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Authors: | Minoru Umeda Isamu Uchida |
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Affiliation: | Department of Applied Chemistry, Faculty of Engineering, Tohoku University, Aramaki-Aoba 07, Aoba-ku, Sendai 980-8579, Japan |
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Abstract: | We have developed a porous-microelectrode (PME) to investigate the electroactivity of catalyst particles for proton exchange membrane fuel cells. The cavity at the tip of the PME was filled with Pt/C catalysts prepared by impregnation method. Cyclic voltammograms (CVs) recorded in 1 N H2SO4 aqueous solution revealed that the active area of the stacked catalysts exist not only at the surface but also inside of the stack. For methanol electrooxidation, 30 wt.% Pt/C exhibited the highest electroactivity, whereas the 50 wt.% Pt/C showed extremely small current. The small current is considered as a result of a small active-surface area. Methanol oxidation peak potential shifted toward cathodic direction as Pt-loading decreased, which agrees well with the Pt-oxide formation potential. The activation energy for methanol oxidation was assessed to be 44±3 kJ mol−1 for all Pt/C catalysts and Pt-disc electrode. |
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Keywords: | Porous-microelectrode Direct methanol fuel cell Pt-loading carbon Methanol electrooxidation Electroactivity |
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