The unique core-shell structure of ZnO/NiO heterojunction as an improved performance of supercapacitors via chemical bath deposition approach
The integration of metal oxide composite nanostructure has attracted great attention in supercapacitors (SCs) applications. Herein, we have fabricated a series of various metal oxide composite nanostructures, such as ZnO nanowires, NiO nanosheets, ZnO/CuO nanowire arrays, ZnO/FeO nanocrystals, ZnO/NiO nanosheets and ZnO/PbO nanotubes via simple and cost-effective chemical bath deposition method (CBD). The electrochemical properties of SCs were examined by cyclic voltammetry (CV), galvanostatic charge-discharge analysis (GCD), and electrochemical impedance spectroscopy (EIS). Among different metal oxide composites, the unique surface morphology of ZnO/NiO nanosheets effectively increases the electron transfer rate and electrical conductivity, which results in improved energy storage properties. The binder-free ZnO/NiO electrode delivered a high specific capacitance /capacity of 1248 F g-1 (599 mAh g-1) at 8 mA cm-2 and long-term cyclic stability of 3000 cycles with a capacity retention of 79%. These results suggest that ZnO/NiO nanosheets show superior performance than the nanowires, nanowire arrays, nanocrystals, and nanotubes. Thus, the present work provides an opportunity to fabricate new metal oxide composite nanostructures with high-performance energy storage devices.