Enhanced electrocatalytic activity of Pt nanoparticles supported on functionalized graphene for methanol oxidation and oxygen reduction.

Reduced graphene oxide (RGO) is modified with 1,1'-dimethyl-4,4'-bipyridinium dichloride (methyl viologen, i.e. MV) by a π-π interaction, and further used as support for immobilization of Pt nanoparticles to prepare a Pt/MV-RGO catalyst for direct methanol fuel cells. Transmission electron microscopy, X-ray powder diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy are used to characterize the morphology and microstructure of the prepared catalyst. Electrocatalytic performance of the as-prepared Pt/MV-RGO hybrid is investigated by cyclic voltammetry, linear scan voltammetry, COads stripping voltammetry and electrochemical impedance spectroscopy. The Pt/MV-RGO hybrid exhibits much higher catalytic activities than Pt/RGO toward both methanol oxidation and oxygen reduction, suggesting that Pt/MV-RGO hybrid could be a promising electrocatalyst for high-performance direct methanol fuel cells applications.