Efficient and Superiorly Durable Pt-Lean Electrocatalysts of Pt-W Alloys for the Oxygen Reduction Reaction

The commercial viability of polymer electrolyte membrane fuel cells in transportation applications will rely on significant reductions in the amount and great improvements in the stability of Pt in their cathodes to catalyze the oxygen reduction reaction (ORR). We demonstrated through first-principle theoretical calculations and experimental measurements that alloying Pt with 5d transition metal W could help to accomplish this aspiration. It was shown that the strong surface segregation tendency of Pt in Pt-W alloys and the peculiar electronic effect of W to Pt allow facile formation of stable Pt-enriched surfaces with likely better-than-Pt ORR activity at Pt-lean alloys such as PtW2, in contrast to the previously reported Pt alloy ORR electrocatalysts which mostly have to be Pt-rich in total composition (e.g., Pt3M). The prepared PtW2 alloy catalysts exhibited a Pt mass activity nearly 4 times higher than the pure Pt catalysts and almost no changes in the activity and surface area in over 30,000 cycles of potential cycling under oxidizing conditions of ORR, in contrast to significant losses seen with the pure Pt catalyst. In addition, the present study also showed a density functional theory-based multiple-descriptor strategy for screening durable and efficient bimetallic catalysts of low precious metal contents.