SURFACE-STRUCTURE EFFECTS IN PLATINUM RUTHENIUM METHANOL OXIDATION ELECTROCATALYSIS/

Catalytic activity of low-index platinum single-crystal faces, Pt(111) , Pt(100), and Pt(110), and polycrystalline platinum toward methanol e lectrooxidation was enhanced by controlled amounts of electrodeposited ruthenium. Platinum surface structure affects all factors involved in the oxidation process: (i) ruthenium coverage corresponding to the hi ghest methanol oxidation rate, (ii) rate of oxidation current decay, ( iii) Tafel slopes and reaction turnovers, and (iv) apparent activation energy. We found a unique methanol oxidation reactivity at the Pt(111 ) surface covered by 0.2 monolayer of ruthenium. The turnover number f rom such a surface at 80 degrees C is approximately 1 order of magnitu de higher than that from the industrial platinum/ruthenium catalyst. T herefore, the Pt(111)/Ru electrode is the best laboratory scale fuel c ell anode for methanol oxidation. We conclude that crystallographic va riables should be exploited in syntheses of novel metal-alloy catalyst s for fuel cell use.