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

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. Microstructural 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-supported 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.