Use of graphene-supported manganite nano-composites for methanol electrooxidation

Binary nano-composites of palladium and a metal (Fe or Cu) manganite on graphene nanosheets (GNS) have been prepared by a microwave-assisted polyol reduction method and investigated as electrocatalysts for the methanol oxidation reaction (MOR) in 1 M KOH at 25 °C. Structural and electrocatalytic surface characterizations of composites are carried out by X-ray diffraction, transmission electron microscopy, X-ray photoelectron microscopy, cyclic voltammetry and chronoamperometry. Results show that new composite catalysts, particularly 40 wt%Pd-x wt%FeMn2O4/GNS (where x = 5, 8, 10 & 15) are MOR active and that the activity is the greatest with the catalyst containing 8 wt% of the oxide. The composite, Pd-8 wt%FeMn2O4/GNS, exhibits much superior catalytic activity as well as stability compared to the base (Pd/GNS) electrode. The enhanced catalytic activity and stability of the Pd/GNS catalyst in presence of the oxide can be ascribed to increased population of adsorbed OH− ions/OH radicals at the electrode surface.