Preparation of Carbon-Supported Core-Shell Au-Pt Nanoparticles for Methanol Oxidation Reaction: The Promotional Effect of the Au Core

摘要

Core-shell Au-Pt nanoparticles with intimate contact of Pt and Au were prepared by a displacement reaction without formation of monometallic Au nanoparticles.The Au-Pt nanoparticles were dispersed on carbon (Au@Pt/C) and were used to catalyze methanol electroxidation in acidic solutions at room temperature.The core-shell nanostructure was confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy,and specific catalytic activities were evaluated by CO anodic stripping voltammetry in 0.5 M H_2SO_4 and by cyclic voltammetry in 1 M CH_3OH + 0.5 M H_2SO_4.The Au@Pt/C catalyst demonstrated enhanced specific activity in methanol electrooxidation and showed multiple CO stripping peaks which were all negatively shifted with respect to a similarly prepared Ag@Pt/C catalyst.The activity enhancement is attributed to the presence of Au underneath a very thin Pt shell where electron exchange between Au and Pt had promoted the formation of active oxygen species on Pt,which facilitated the removal of inhibiting CO-like reaction intermediates.