Hierarchical NiO nanoflake coated CuO flower core–shell nanostructures for supercapacitor

In this work, we developed a simple and cost-effective approach to prepare the hierarchical NiO/CuO nanocomposite without any surfactant. The morphology and structure of the hybrid nanostructure was examined by focus ion beam scanning electron microscopy (FIB/SEM), X-ray diffraction spectroscopy (XRD) and high-resolution transmission electron microscopy (HRTEM). Furthermore, the electrochemical properties of the hierarchical NiO/CuO nanocomposite electrodes were elucidated by cyclic voltammograms, galvanostatic charge/discharge tests and electrochemical impedance spectroscopy in 6 M KOH electrolyte. The electrochemical results demonstrated that this unique NiO/CuO nanostructure exhibited a specific capacitance of 280 F g⁻¹ and excellent cycling stability (91.4% retention after 3000 cycles). The remarkable electrochemical performance coupled with the facile synthesis of the hierarchical NiO/CuO nanocomposite indicated the great application potential in supercapacitors.