Electrodeposition of nano crystalline cobalt oxide on porous copper electrode for supercapacitor

The cobalt oxide thin films were prepared by electrodeposition methods on to porous copper substrate. As-deposited films were obtained as Co₃O₄ films with the help of heat treatment at 300 °C for 2 h. Their structural and surface morphological properties were investigated by using X-ray diffraction, Fourier transformation analysis and field emission scanning electron micrograph (FESEM), atomic force microscope, energy dispersive X-ray analysis techniques (EDAX). The X-ray diffractogram reveals the formation of cobalt hydroxide CoOOH with orthorhombic crystal structure and cobalt oxide Co₃O₄ with cubic crystal structure. The FESEM micrographs confirms the morphology of prepared films, also EDAX spectra confirms the presence of Co and O elements of the solid films. The electrochemical performance of the films was studied in aqueous 1 M KOH electrolyte using cyclic voltammetry. The cyclic voltammograms exhibits symmetric nature and increase in capacitance with respect to the film thickness. The maximum specific capacitance of cobalt hydroxide CoOOH is 602 F g⁻¹ and cobalt oxide Co₃O₄ is found to be as 630 F g⁻¹. The above investigation shows that low-cost cobalt oxide electrode can be a potential application in supercapacitor.