Effect of deposition parameters on spray pyrolysis synthesized CuO nanoparticle thin films for higher supercapacitor performance

In this study, copper oxide (CuO) thin films were synthesized at different deposition temperatures on fluorine doped tin oxide coated glass (FTO) substrates by spray pyrolysis for supercapacitor applications. The physical and electrochemical properties of the as-synthesized CuO samples were characterized via different analytical techniques such as X-ray diffraction (XRD), X-ray photoelectron spectroscopy, scanning electron (SEM) microscopy, surface wettability tests, and electrochemical measurements. The results showed that the deposition temperature affected their structural, morphological, and supercapacitor properties. The higher specific capacitance and extensive charge/discharge capability of the nanoparticle-like CuO thin films demonstrated their suitability as outstanding candidates in electrochemical applications. The evaluated specific capacitance further confirmed the effect of the deposition temperature on the supercapacitor performance of the CuO electrodes; its values for the thin films synthesized at 300, 350, and 400 °C were 363, 691, and 487 F g^{− 1}, respectively, at a scan rate of 5 mV s^{− 1} in a 2 M Na₂SO₄ aqueous electrolyte. Hence, this study demonstrates that the surface morphology and electrochemical supercapacitive properties of materials are dependent on the deposition temperature of CuO thin films.