Nanostructured CuO thin film deposited on stainless steel using spray pyrolysis as supercapacitor electrode

Abstract

We investigated the effects of different annealing temperatures on cupric oxide (CuO) films as supercapacitor electrode. CuO films were grown on stainless steel substrates via spray pyrolysis and annealed for two hours at different temperatures of 160 °C, 250 °C, and 400 °C. X-ray diffractometry (XRD) and micro-Raman spectroscopy (MRS) confirmed the monoclinic phase of CuO films. At higher annealing temperatures, narrower XRD peaks were observed due to reduced defects and increased grain size. The supercapacitive properties of the CuO electrode were evaluated using three-electrode cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in 1.0 M aqueous sodium sulfate (Na2SO4) electrolyte. At a scan rate of 10 mV s-1, the highest specific capacitance of 87.06 F g-1 was achieved from the CuO electrode annealed at 400 °C. Furthermore, repeated CV scans up to the 1000th cycle revealed that the CV plots have retained its shape and capacitance up to 84.68% of the original value. The obtained results revealed that the CuO nanostructures grown by spray pyrolysis can be used as an electrode for supercapacitors.