Effect of annealing on hydrothermally deposited Co₃O₄-ZnO thin films for supercapacitor applications

Co₃O₄-ZnO thin films were synthesis using hydrothermal technique in an alkaline bath. The alkalinity of the reaction bath was maintained at pH values of 10 and 12 using an aqueous ammonia solution. Fabricated films were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and UV-visible spectroscopy for morphological, structural and optical properties of the fabricated thin films respectively. Electrochemical behaviour of the films were studied using potentiostat to carry out its cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge discharge (GCD) to ascertain its usefulness as supercapacitors electrodes materials. The maximum specific capacitance of 730F/g and electrode resistance of 0.0076? electrode was obtained. Calculated values of the band gap energy, specific capacitance and its resistance indicate its possible applications in photovoltaic energy storage systems and supercapacitors.