Preparation of nanocrystalline nickel oxide thin films by sol–gel process for hydrogen sensor applications

Preparation of nanocrystalline NiO thin films by sol–gel method and their hydrogen (H2) sensing properties were investigated. The thin films of NiO were successfully deposited on the glass and SiO2/Si substrate by a sol–gel coating method. The films were characterized for crystallinity, electrical properties, surface topography and optical properties as a function of calcination temperature and substrate material. It was found that the films produced by this method were polycrystalline and phase pure NiO. The H2 gas sensitivity of these films was studied as a function of H2 concentration and calcination temperature. The results indicated that the sol–gel derived NiO films could be used for the fabrication of H2 gas sensors to monitor low concentration of H2 in air quantitatively at low temperature range (< 200 °C).