Residual Silver Remarkably Enhances Electrocatalytic Activity and Durability of Dealloyed Gold Nanosponge Particles.

Abstract

Percolation dealloying of multimetallic alloys entangles the selective dissolution of the less-noble elements with nanoscale restructuring of the more-noble components, resulting in the formation of spongelike, nanoporous architectures with a unique set of structural characteristics highly desirable for heterogeneous catalysis. Although the dealloyed nanoporous materials are compositionally dominated by the more-noble elements, they inevitably contain residual less-noble elements that cannot be completely removed through the percolation dealloying process. How to employ the less-noble elements to rationally guide the structural evolution and optimize the catalytic performances of the dealloyed noble metal nanocatalysts still remains largely unexplored. Here, we have discovered that incorporation of Ag into Au-Cu binary alloy nanoparticles substantially enhances the Cu leaching kinetics while effectively suppressing the ligament coarsening during the nanoporosity-evolving percolation dealloying of the alloy nanoparticles. The controlled coleaching of Ag and Cu from Au-Ag-Cu ternary alloy nanoparticles provides a unique way to optimize both the surface area-to-mass ratios and specific activities of the dealloyed nanosponge particles for the electrocatalytic oxidation of alcohols. The residual Ag in the fully dealloyed nanosponge particles plays crucial roles in stabilizing the surface active sites and maintaining the nanoporous architectures during the electrocatalytic reactions, thereby greatly enhancing the durability of the electrocatalysts. The insights gained from this work shed light on the underlying roles of residual less-noble elements that are crucial to the rational optimization of electrocatalysis on noble-metal nanostructures.