Nanostructured CuO Thin Films for High-Performance Supercapacitors: A Comparative Study on Capacitance Enhancement

Abstract

This study explores the supercapacitive properties of nanostructured CuO thin films synthesized through sol-gel deposition, electrodeposition, and thermal oxidation. The films were characterized for their structural and morphological features, and their electrochemical performance was evaluated using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD).The results demonstrate that electrodeposited CuO thin films exhibit superior capacitance and cycling stability compared to sol-gel and thermally oxidized films, highlighting the importance of fabrication technique in optimizing supercapacitor performance.CuO thin films were successfully synthesized using three different methods: sol-gel deposition, electrodeposition, and thermal oxidation, to investigate their structural, morphological, and electrochemical properties for supercapacitor applications. The sol-gel method involved spin-coating copper nitrate on conductive substrates followed by annealing at 300°C, while the electrodeposition technique utilized copper sulfate solution and thermal oxidation involved direct oxidation of copper foil at 450°C. Structural characterization using X-ray diffraction (XRD) confirmed the formation of monoclinic CuO with preferential growth along the (1̲11) plane. Scanning Electron Microscopy (SEM) revealed uniform, granular morphology, and crystallite sizes increased with annealing temperature, reaching a maximum of 24 nm at 350°C. The electrochemical performance of the films was evaluated through cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), showing improved capacitance and cycling stability. The films prepared at 350°C exhibited the best crystallinity and electrochemical performance, making them suitable for use in energy storage devices. These results highlight the influence of synthesis methods and annealing conditions on the structural and electrochemical properties of CuO thin films, offering insights into their potential for supercapacitor applications.