The performance of a liquid-feed direct methanol fuel cell employing a proton-exchange membrane electrolyte with Pt-Ru/C as anode and Pt/C as cathode is reported. The fuel cell can deliver a power density of ca. 0.2 W/cm2 at 95°C, sufficient to suggest that the stack construction is well worthwhile. Methanol crossover across the polymer electrolyte at concentrations beyond 2 M methanol affects the performance of the cell which appreciates with increasing operating temperature. Inh'ocluction Electric vehicles powered with polymer-electrolyte fuel cells using hydrogen as fuel are presently being tested for vehicular applications.1 But hydrogen is difficult both to store and transport. The most satisfactory approach seems to be to electro-oxidize a liquid fuel at the anode. Methanol is the only liquid fuel that has any substantial electroactivity and can be directly oxidized to carbon dioxide and water on catalytically active anodes in a direct methanol fuel cell (DMFC).2'3 However, the fundamental limitation in the practical utilization of such fuel cells has been the existence of electrochemical losses at both the anode and cathode, leading to poor overall conversion efficiencies.45 Recently, a liquid-feed polymer-electrolyte DMFC with power outputs near 0.15 W/cm2 at operational tempera
The effect of acid/base functional-groups associated with platinized-carbon electrodes on their catalytic activity toward electro-oxidation of methanol in sulfuric acid electrolyte at 60~ is studied. Platinized-carbon electrodes with small amounts of functional groups exhibit higher catalytic activity compared to those with large concentrations of acidic/basic surface functionalities. The overpotential for methanol oxidation is minimum on electrodes of platinized carbons with pHzpc values between 6 and 7. An x-ray photoelectron spectroscopic study of various platinized carbons suggests that the acid/base surface functional-groups produce ample amounts of surface Pt-oxides and a consequent decrease in activity toward methanol oxidation.
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