Au[sbnd]Pt core-shell electrocatalysts for oxygen reduction reaction through combining the spontaneous Pt deposition and redox replacement of underpotential-deposited Cu

Abstract

Core-shell structured AuPt nanoparticles are promising electrocatalysts for oxygen reduction reaction (ORR) in fuel cells due to the superior durability as well as high activity. We report the fabrication of AuPt core-shell nanoparticles by combining the spontaneous Pt deposition and redox replacement of underpotential-deposited (UPD) Cu. It is shown that redox replacement of UPD Cu, a commonly used approach to fabricate Pt monolayer catalysts, only can produce Pt atomic layer partially covering the Au nanoparticles, leading to insufficient Au utilization in ORR. By pre-modifying the Au nanoparticles with Pt through spontaneous deposition, which produces relatively uniformly dispersed Pt atoms on the Au nanoparticles at moderate and low Pt contents, the subsequent UPD Cu and redox replacement yield a Pt overlayer with a high coverage. The resulted core-shell nanoparticles show higher precious metal (Pt + Au) utilization than that obtained either through the single approach of the spontaneous Pt deposition or redox replacement of UPD Cu, or double redox replacement of UPD Cu.