▎ 摘　　要

An effective, simple, low temperature and environmentally benign supercritical fluid (SCF) route is presented for preparing graphene-supported metal nanoparticles. With the assistance of supercritical carbon dioxide (SC CO2), ultrafine PtRu nanoparticles with an average size of 2.87 nm were very uniformly distributed on the surfaces of functionalized graphene sheets (FGSs) by the reduction of a mixture of H2PtCl6 and RuCl3 precursors. The catalytic property of the as-prepared composites for methanol oxidation was investigated by cyclic voltammetry and chronoamperometry. In comparison with their carbon black (Vulcan XC-72) counterparts, the PtRu/FGSs composites showed considerably improved catalytic activity and stability for methanol oxidation. The high surface area of graphene and even distribution of ultrafine bimetallic particles are vital for the superior electrocatalytic performance of the PtRu/FGSs composites. The findings suggest that highly efficient graphene-supported metallic electrocatalysts can be fabricated by the supercritical fluid method and graphene as a favorable electrocatalytic carrier, which has promising potential application in direct methanol fuel cells.