Reduced Graphene Oxide Supported Bimetallic Cobalt–Palladium Nanoparticles with High Catalytic Activity towards Formic Acid Electro-oxidation

Abstract

In this work, we report the growth of uniformly dispersed bimetallic cobalt–palladium nanoparticles (NPs) on reduced graphene oxide (RGO) nanosheets to prepare CoPd–RGO composites via a two-step procedure, where firstly formed Co NPs are used as seeds for the subsequent growth of Pd. The generation of Co NPs on RGO is performed by an in-situ reduction reaction with the reducer ethylene glycol under oil bath at 180 °C. According to composition, size and microstructure analyses, NPs in the resulting CoPd–RGO have an average particle size of 5 nm, and Pd is added to one side of Co NPs, thus forming Co–Pd bimetallic interfaces. The involved formation mechanism is suggested. The composite is used as an electro-catalyst for the formic acid oxidation in alkaline electrolyte, and the catalytic performance is investigated by cyclic voltammetry and chronopotentiometry etc. The results show that the composite has the highest electro-catalytic activity, the best electrochemical stability and the highest resistance to CO poisoning than those of the monometallic composite and commercial Pd black at the same loading. This is due not only to the small size of NPs with Co–Pd bimetallic interfaces providing more active atoms accessible for reactants, but also to the electric synergistic effect between metals and graphene.