Supersaturation-controlled surface structure evolution of Pd@Pt core–shell nanocrystals: enhancement of the ORR activity at a sub-10 nm scale

Abstract

Here, we designed and implemented a facile strategy for controlling the surface evolution of Pd@Pt core–shell nanostructures by simply adjusting the volume of OH⁻ to control the reducing ability of ascorbic acid and finally manipulating the supersaturation in the reaction system. The surface structure of the obtained Pd@Pt bimetallic nanocrystals transformed from a Pt {111} facet-exposed island shell to a conformal Pt {100} facet-exposed shell by increasing the pH value. The as-prepared well aligned Pd@Pt core–island shell nanocubes present both significantly enhanced electrocatalytic activity and favorable long-term stability toward the oxygen reduction reaction in alkaline media.