Constructing CoO Nanowire@NiCoO Nanosheet Hierarchical Array as Electrode Material for High-Performance Supercapacitor.

The CoO nanowire@NiCoO nanosheet hierarchical array was constructed on Ni foam using hydrothermal and annealing approaches in turn, from which a NiCoO nanosheet could self-assemble on the CoO nanowire. The structure and morphology of the CoO nanowire@NiCoO nanosheet hierarchical array were characterized via XRD, EDS, SEM, and FESEM, respectively. The electrochemical performance of the composite array was measured via a cyclic voltammetry curve, galvanostatic current charge-discharge, charge-discharge cycle, and electrochemical impedance and then compared with the CoO nanowire. The results show that the CoO nanowire@NiCoO nanosheet hierarchical array could reach a high value of 2034 F g at a current density of 2.5 A g. After 5000 galvanostatic charge-discharge cycles, the specific capacitance of the CoO nanowire@NiCoO nanosheet hierarchical array could still maintain 94.7% of the original value. Therefore, the CoO nanowire@NiCoO nanosheet hierarchical array would be a desirable electrode material for a high-performance supercapacitor.