Alloys of platinum and early transition metals as oxygen reduction electrocatalysts

Abstract

The widespread use of low-temperature polymer electrolyte membrane fuel cells for mobile applications will require significant reductions in the amount of expensive Pt contained within their cathodes, which drive the oxygen reduction reaction (ORR). Although progress has been made in this respect, further reductions through the development of more active and stable electrocatalysts are still necessary. Here we describe a new set of ORR electrocatalysts consisting of Pd or Pt alloyed with early transition metals such as Sc or Y. They were identified using density functional theory calculations as being the most stable Pt- and Pd-based binary alloys with ORR activity likely to be better than Pt. Electrochemical measurements show that the activity of polycrystalline Pt₃Sc and Pt₃Y electrodes is enhanced relative to pure Pt by a factor of 1.5–1.8 and 6–10, respectively, in the range 0.9–0.87 V.