Novel Flower-Like CuO/N-rGO as Enhanced Electrocatalyst for Oxygen Reduction Reaction

Abstract

Flower-like copper oxide (CuO)/nitrogen-doped reduced graphene oxide (N-rGO) was synthesized through a one-pot microwave hydrothermal method by using polyvinylpyrrolidone (PVP) as surfactant. In the process, in situ formation of nanomaterial CuO, reduction of graphene oxide and doping of nitrogen species occurred simultaneously in urea solution. The structural and surface properties of the material were investigated by field emission scanning electron microscopy (FESEM) and transmission electron microscopies (TEM), the energy dispersive spectroscopic (EDS) and powder X-ray diffraction (XRD). This showed the flower-like CuO with an interconnected architecture was successfully uniformed and grown on the surface of N-rGO. Moreover, the surfactant PVP and urea were found to be the key factors to control the morphology of the CuO nanostructure. Electrochemical investigations indicated that the CuO/N-rGO composite exhibited a significantly enhanced ORR activity in comparison to pure CuO and N-rGO in an alkaline solution. The enhancement in ORR activity of CuO/N-rGO composite can be attributed to the synergistic effects of good electron transport from N-rGO as well as abundance of exposed catalytic sites and meso/macroporosity from CuO nanostructures.