Preparation of NiO Thin Films and Their Application for NO2 Gas Detection

Abstract

The current study reports the successful preparation of NiO thin films on the surface of a ceramic substrate using chemical spray pyrolysis, followed by their fabrication as NO2 gas sensors. A 0.2 M nickel chloride solution was utilized for the purpose. We investigated the influence of different deposition times on the surface morphology, phase structure, optical transmittance, and NO2 gas sensitivity of NiO thin films. The results suggested that, at a deposition time equal to 10 min, the NiO-10 thin film deposited by chemical spray pyrolysis presented a large number of honeycomb pores on the surface, thereby possessing a high specific surface area and porous structure (the porosity: ~5.6%). Among the four synthesized films, the NiO-10 thin film had the highest optical transmittance in the visible and near-infrared ranges. At an operating temperature of 200°C, the NiO-10, NiO-20, NiO-30, and NiO-40 thin film gas sensors had respective sensitivities of 57.8%, 53.3%, 40.5%, and 34.2%. Additionally, the NiO-10 thin film gas sensor demonstrated high stability and selectivity for sensing NO2 gas. NiO-10 thin-film demonstrated a corrosion current density equal to 5.46 X 10-5 A/cm2