The effect of Sn content on the electrocatalytic properties of Pt-Sn nanoparticles dispersed on graphene nanosheets for the methanol oxidation reaction

摘要

Direct methanol fuel cell (DMFC) electrode catalysts with improved electrochemical properties have been prepared by dispersing platinum-tin (Pt-Sn) nanoparticles onto graphene sheets. During the deposition, a majority of the oxygenated functional groups on the graphene oxide nanosheets were removed, resulting in the formation of graphene. Micro-structural characterization shows that metallic Pt, Pt-Sn alloy and tin dioxide (SnO2) nanoparticles were distributed on the graphene sheets, representing different lattice planes during the synthetic process. In terms of the electrocatalytic properties, graphene-sup-ported Pt-Sn and graphene-supported Pt catalysts exhibited much higher current densities compared with that of commercial carbon black-supported Pt catalysts. Graphene-supported Pt-Sn increased the electrocatalytic activity, which is strongly influenced by the addition of Sn in its alloyed and oxidized forms, boosting the reaction more readily because of the lower oxidation potential.