We report on the environmentally friendly synthesis of cupric oxide zinc oxide nanocomposite (CuO-ZnO NCs) utilising Azadirachta indica (neem) leaf extract. The CuO-ZnO NCs exhibited an average crystallite size of 20 nm. Powder X-ray diffraction (PXRD) analysis confirmed their hexagonal crystal structure with a space group of P63/mmc. The synthesized CuO-ZnO NCs were comprehensively characterized using various analytical techniques, including X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM/HRTEM), Selected Area Electron Diffraction (SAED), and Energy Dispersive X-ray Spectroscopy (EDAX). While UV-diffuse reflectance spectroscopy (UV-DRS) determined the bandgap energy of CuO-ZnO NCs to be 3.37 eV. When exposed to UV radiation (from 0 to 120 min), the degradation tests were conducted for two dyes: Fast Orange (FO) and Congo Red (CR). CuO-ZnO NCs demonstrated the highest photocatalytic activity for Congo Red (CR). Excellent redox potential output was determined by cyclic voltammetry (CV) in an electrochemical evaluation of the produced material using graphite electrode paste in 1 M KOH electrolyte. Electrochemical impedance spectroscopy (EIS) research has demonstrated that the decreased charge transfer resistance of CuO-ZnO NCs is responsible for their improved behaviour. After computation, it was discovered that the CuO-ZnO NCs specific capacitance values were 31 Fg−1 at a scan rate of 30 mVs−1.
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