Synthesis of core–shell Au@Pt nanoparticles supported on Vulcan XC-72 carbon and their electrocatalytic activities for methanol oxidation

Abstract

Au@Pt core–shell nanoparticles were successfully synthesized by successive reduction of HAuCl4 and H2PtCl6 and were then assembled on Vulcan XC-72 carbon surface (noted as Au@Pt/C). The morphology and distribution of Au@Pt nanoparticles were characterized by UV–vis spectroscopy, transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy (EDS) and the corresponding result is that core–shell like structure is observed. The Au@Pt/C catalysts with different Au/Pt atomic ratios were characterized by TEM, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The electrocatalytic activities of Au@Pt/C catalysts were investigated by cyclic voltammetry (CV) in 1.0M H2SO4+1.0M methanol aqueous solution. The effects of Au/Pt atomic ratio, CV scan rate and methanol concentration on the peak current of methanol oxidation and the long-term cycle stability were also discussed. The results revealed that compared with Au@Pt/C (1:4, 1:1, 2:1) catalysts, Au/C catalyst, and Pt/C catalyst, Au@Pt/C (1:2) catalyst exhibits higher electrocatalytic activity toward methanol oxidation in acidic media, and the peak current density of Au@Pt/C (1:2) catalyst is about 2.5 times as large as that of Pt/C catalyst without Au core. Further more, Au@Pt/C (1:2) catalyst shows good long-term cycle stability and 91.1% value of peak current of methanol oxidation remains after 200 cycles.