The influence of deposition temperature on the electrodeposition of NiO films on ITO-glass substrate

An investigation on the influence of deposition temperature on the formation of NiO films on ITO-glass was carried out. The films were electrochemically deposited from bath solution containing 0.1 M nickel sulfate, 0.1 M sodium acetate and 0.1 M sodium sulfate at pH 6.7 by applying constant potential of + 1.1 V at various deposition temperatures. The microstructure and surface morphology of the NiO thin films were characterized by X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM), respectively. Deposition temperature has significantly changed the surface morphology of NiO films. The structure of NiO films becomes porous as the bath solution was heated and the pores size becomes larger as higher deposition temperature was used. The porous films electrodeposited at 40°C and 60°C have good electrochemical activity as they have high specific surface area and they are easily accessible by electrolyte which leading to a decrease in diffusion resistance. However, the porous films prepared at 80°C have poor electrochemical behavior probably due to the entrapment of OH^- ions in the thick NiO structure during cycling.