References

1. M. Uchida, Y. Aoyama. N. Eda. and A. Ohta. J. Electrochem. Soc. . 142.463 (1995).

2. H. A Gastcigcr. N. Markovic, P. N. Ross. Jr.. and E. J. Cairns. Electrochim. Acta. 39. -v. 1825 (1994).

COMPARISON OF Pt-BASED BINARY AND TERNARY ALLOY ANODE CATALYSTS FOR POLYMER ELECTROLYTE DIRECT METHANOL FUEL CELLS

Renxuan Liu. K. L. Ley, Cong Pu. E. Reddington, K. Triantefillou,T.E. Mallouk, E. S. Smotkin Department of Chemical and Environmental Engineering Illinois Institute of Technology, Chicago, IL 60616

INTRODUCTION:

As an anode catalyst, Pt is highly active for the adsorption and dehydrogenation of methanol, however, the surface is poisoned by CO.1 To oxidize CO to C02, a second oxygen atom is required from an adjacent adsorbed water mo!ecuIe.(see Figure 1) Bifunctional alloys composed of Pt and a second metal M, able to activate H20 (forming -OHal,) at low potentials, are candidate materials for methanol electro-oxidation catalysts.2 A proposed mechanism is: Pt + CH3OH -> Pt-CH3OH„j, [1]

Figure 2 shows that metals which enhance methanol oxidation activity when alloyed with Pt have similar M-0 bond strengths (see bold print), suggesting that the best binary alloy catalysts have second metals that are optimized with respect to the ability to oxidatively adsorb water (affecting steps |31&[4]). and the ability to dissociate M-0 bonds to yield C02 (step [5]).3

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