Rational rope-like CuCo2O4 nanosheets directly on Ni foam as multifunctional electrodes for supercapacitor and oxygen evolution reaction

Transition metal oxides have shown promising candidates for energy storage and conversion devices, but the limited electroactive sites may greatly limit the further improvement. Herein, we successfully achieve rope-like CuCo2O4 nanosheets directly on Ni foam, which acts as multifunctional electrodes for super-capacitor and oxygen evolution reaction (OER). The rope-like nanosheets with the ultrathin thickness and large surface areas can effectively increase the number of active sites, resulting in enhanced electrochemical performances. In addition, directly growing nanostructures on conductive Ni foam can endows the electrode materials with higher conductivity and richer active sites. Consequently, obtained rope-like CuCo2O4 nanosheets show the superior electrochemical performances toward supercapacitor and OER. In detail, obtained rope-like CuCo2O4 nanosheets display a high capacity of 5.84 F cm(-2) (0.65 mAh cm(-2)) at 5 mA cm(-2), as good as good stability. The asymmetric supercapacitor made of CuCo2O4 (positive electrode) and activated carbon (negative electrode) also show a high energy density of 0.55 mWh cm(-2) at 8 mW cm(-2) power density. In addition, obtained rope-like CuCo2O4 nanosheets only require a low overpotential of 220 mV at 10 mA cm(-2) for OER, and also maintain the outstanding long-term durability. These remarkable performances of rope-like CuCo2O4 hold great promise for energy storage and conversion devices. (C) 2020 Elsevier B.V. All rights reserved.