▎ 摘　　要

High quality thermally exfoliated reduced graphene oxide (RGO) nanosheets decorated with platinum nanocrystals have been synthesized using a simple environmentally benign process. The electrocatalytic behaviour of the Pt-RGO nanohybrid for methanol oxidation was studied using cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy. High resolution transmission electron microscopy shows uniform dispersion of Pt nanoparticles of similar to 2-4 nm size. X-ray diffraction and selected area diffraction studies reveal (111) orientation of the platinum nanoparticles. The cyclic voltammetry and chronoamperometry results indicate higher catalytic activity and stability for Pt-RGO compared to commercial Pt-C. The electrochemical active surface area of Pt-RGO (52.16 m(2)/g) is found to be 1.5 times that of commercial Pt-C. Impedance spectroscopy shows different impedance behaviour at different potential regions, indicating change in methanol oxidation reaction mechanism with potential. The reversal of impedance pattern to the second quadrant, at potentials higher than similar to 0.40 V, indicates change in the rate determining reaction. (C) 2015 Elsevier Ltd. All rights reserved.