CuO nanosheets/rGO hybrid lamellar films with enhanced capacitance

Abstract

CuO nanosheets (NSs)/reduced graphene oxide (rGO) hybrid lamellar films were prepared by vacuum filtration of CuO NSs/GO composite dispersions, followed by hydrothermal reduction. The CuO NSs/GO composite dispersions were assembled electrostatically by mixing a negatively charged GO sheets aqueous solution with a positively charged CuO NSs aqueous dispersion at room temperature. The prepared CuO NSs/rGO hybrid lamellar films exhibited a specific capacitance of 163.7 F g⁻¹, which is much higher than the 69.7 F g⁻¹ of CuO NSs and 66.0 F g⁻¹ of rGO. The effective specific capacitance was 82.5 F g⁻¹ after 1000 cycles, which was more than two times the 32.7 F g⁻¹ of CuO NSs electrodes. The synergistic redox activity of the CuO NSs, in combination with the high electronic conductivity of the rGO and the unique CuO NSs spaced sandwich-like porous structures, dominated the excellent capacitance of CuO NSs/rGO hybrid lamellar films. The sandwiched, lamellar, porous structures not only provide plenty of paths for electrolyte-ion access to the CuO NSs but also expose the rGO sheets to the electrolyte as much as possible. This process provides a potential way to synthesise metal oxide/GO composite electrodes for capacitors.