Hierarchical 3D-flower-like CuO nanostructure on copper foil for supercapacitors

We report a trouble-free chemical synthesis of copper oxide (CuO) nanoflowers on flexible copper foil (Cu) and their use as electrodes for supercapacitors. Various characterization techniques, such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HR-TEM), and Brunauer–Emmett–Teller (BET) analysis, have been used to characterize CuO nanostructure. Supercapacitive properties show that CuO electrodes exhibit a high specific capacitance of about 498 F g⁻¹ at 5 mV s⁻¹, with a high energy density of 26 W h kg⁻¹ in KOH electrolyte. Moreover, impedance analysis showed lower ESR value, high power performance, and an excellent rate as well as frequency response for the CuO electrodes. The excellent electrochemical properties of the CuO electrodes indicate that they have many potential applications in high-performance supercapacitors.