Self-driven microstructural evolution of Au@Pd core–shell nanoparticles for greatly enhanced catalytic performance during methanol electrooxidation

Abstract

The lack of direct insight into the microstructural evolution of catalytic materials under electrochemical polarization has inhibited the development of heterogeneous catalysts. By investigating a typical Au@Pd core–shell nanostructure, the present study discloses the microstructural evolution of heterogeneous catalytic materials during the methanol electrooxidation reaction (MOR). The electrocatalytic activity of the as-prepared Au@Pd_core–shell nanoparticles continuously increased during the first 100 successive voltammetry cycles of the MOR. Microstructural characterization studies revealed that during the MOR, an Au/Pd mixed bimetallic shell was formed by the self-driven microstructural evolution of the Au@Pd_core–shell nanoparticles. Both the experimental and calculation results indicated that the Au/Pd mixed bimetallic shell reduced the binding strength of OH⁻ and CO on the catalyst surface. The exposed Au atoms in the shell region also produced large-scale reactive ˙OH radicals that facilitated the oxidative removal of the adsorbed carbonaceous species from the adjacent Pd active sites.