The origin of enhanced electrocatalytic activity of Pt-M (M = Fe, Co, Ni, Cu, and W) alloys in PEM fuel cell cathodes: A DFT computational study

The origin of enhanced electrocatalytic activity of Pt-M (M = Fe, Co, Ni, Cu, and W) alloy catalysts in PEM fuel cell cathodes have been investigated by the periodic DFT geometry optimization and electronic structure calculations. The stability of Pt-M alloy catalysts and the electrocatalytic activity have been explained, and we confirmed that the electronic structure of surface Pt is tuned after alloying Pt with non-noble transition metals, thus leading to enhancement of the electrocatalytic activity of Pt-M alloys for the ORR. Meanwhile, a positive shift in reversible potential was predicted for OHads formation from H2O oxidation on the Pt3M alloy catalysts with Pt-skin compared to the pure Pt. Therefore, this improvement of electrocatalytic activity of the ORR can be also attributed to a positive shift of the onset potential for forming OHads on the alloys relative to the Pt catalyst; thereby the overpotential for O-2 reduction is reduced. In these ways we could screen new electrocatalysts for the ORR. (C) 2014 Elsevier B.V. All rights reserved.