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 electrooxidation 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 highest 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 from such a surface at 80 degrees C is approximately 1 order of magnitude higher than that from the industrial platinum/ruthenium catalyst. Therefore, the Pt(111)/Ru electrode is the best laboratory scale fuel cell anode for methanol oxidation. We conclude that crystallographic variables should be exploited in syntheses of novel metal-alloy catalysts for fuel cell use.