Analyses of Oxygen Reduction Reaction at Pt-Based Electrocatalysts

Abstract

We first reported that enhanced activities in oxygen reduction reaction (ORR) are obtained at Pt skin-layer formed on the surfaces of alloyed Pt with non-precious metals such as Fe, Co, Ni, etc. and also that a positive core level shift in Pt4f7/2 was observed at the Pt skins, due to the modification of the Pt electronic structures. It was also found that such an enhancement is induced without changing the activation energy but the corresponding frequency factor value Z from that of pure Pt. The enhancement mechanism is discussed with the experimental data obtained by using electrochemical-XPS system on adsorbed O-containing species at the Pt skin-layers in comparison with pure Pt. The enhancement, or increased Z values, can be correlated to the increase in Oads formed by dissociative adsorption of O2, resulting in the enhanced activity.