Nanostructured CuO directly grown on copper foam and their supercapacitance performance

Nanostructured CuO with diverse morphology was directly grown on copper foam. Their supercapacitance performance was investigated and correlated with the morphology. CuO nanowires, nanosheets, and flower-like nanostructures were formed on copper foam which acts as both the substrate of CuO formation and the current collector of the electrode. Their morphology was examined by scanning and transmission electron microscopy and their phase structure was analyzed by X-ray diffraction spectroscopy. The supercapacitance of the nanostructured CuO on copper foam was investigated by cyclic voltammetry, galvanostatic charge/discharge measurements and electrochemical impedance spectroscopy. Results showed that the specific capacitance of the nanostructured CuO strongly depends on its morphology and dimension. CuO nanosheets exhibited higher specific capacitance than nanowires and flower-like nanostructure. The specific capacitance of the CuO nanosheets reached 212 Fg(-1) at a current density of 0.41 mA mg(-1) in 6.0 mol dm(-3) KOH electrolyte. The capacitance loss is around 15% after 850 charge/discharge cycles at 0.41 mA mg(-1) and the majority of capacitance loss occurred in the initial 50 cycles (8.1%). (C) 2012 Elsevier Ltd. All rights reserved.