Electrocatalysis of the Oxygen Reduction Reaction at Pt and Pt-Alloys

Abstract

We have clarified for Pt nanoparticles supported on carbon black that the oxygen reduction reaction (ORR) activities are not affected by differences in the particle size. Enhanced activities in the ORR have been demonstrated at Pt alloyed with non-precious metals such as Fe, Co, and Ni. By use of multiple analysis methods, we found that the dissolution of the surface alloy layer was followed by a rearrangement of the remaining Pt layer, resulting in a Pt skin layer, which can protect the underlying bulk alloy. It was shown that a modified electronic structure at the Pt skin layer induced enhanced ORR activity due to an increased coverage of oxygen atoms. These results contribute to establishing a clear strategy for the design of highly active electrocatalysts for fuel cells.