Substrate-integrated core–shell Co3O4@Au@CuO hybrid nanowires as efficient cathode materials for high-performance asymmetric supercapacitors with excellent cycle life

Abstract

Here we demonstrate a facile strategy to boost the electrochemical performance of Co₃O₄ based electrodes through a unique Co₃O₄@Au@CuO core–shell nanowire (NW) electrode design. Ultra-thin interconnected nano-sheets of Co₃O₄ have been uniformly coated on Au@CuO NWs, formed via Au sputtering on CuO NWs directly grown on Cu foil, providing an ameliorated surface area for electrochemical reactions together with the Au interlayer serving as the current accumulator. The results suggest that the incorporation of the Au interlayer into Co₃O₄@Au@CuO core–shell NWs dramatically improves their electrochemical performance in terms of capacitance and rate capability as compared to Co₃O₄@CuO NWs. Accordingly, the Co₃O₄@Au@CuO core–shell NW electrode reaches a specific capacitance of about 1141 F g⁻¹, equivalent to an areal capacitance of about 240 mF cm⁻², at a current density of 4.8 A g⁻¹. Moreover, the ASC device assembled with a Co₃O₄@Au@CuO core shell NW cathode and an α-Fe₂O₃ nanorod anode exhibits an impressive volumetric energy density of 0.23 mW h cm⁻³ (equivalent to 33.8 W h kg⁻¹) with a high power density of 270 mW cm⁻³ (equivalent to 40.4 kW kg⁻¹) and a remarkable capacitance retention of ∼100% during 10 000 cycles. Indeed, this study would help design advanced high-performance ASCs with core–shell NW electrodes.