Investigation of gamma-ray irradiation induced phase change from NiO to Ni2O3 for enhancing photocatalytic performance

An Irradiated nickel oxide (NiO) thin film was deposited onto glass substrates at 723 K by the spray pyrolysis using nickel chloride as precursors. The obtained films were irradiated by gamma-radiation doses varying from 180 Gy to 10 kGy. The structure and optical properties of the samples were examined by X-ray diffraction, UV–vis spectrometer and photoluminescence measurement. Un-irradiated and irradiated NiO thin films have a cubic structure with the same preferred orientation along the plane (111). XRD investigation shows that, the intensity of preferred orientation and crystallite size depend on gamma-radiation dose. For a study of the dose effect, it is very important to optimize the precursor concentration. With a concentration of 5.10−2M precursor NiCl2 and a dose of 10 kGy, we obtain a thin film of Ni2O3. With a 10 kGy dose we obtain a new dominant phase, Ni2O3, which induced an activation of the visible range under the effect of gamma rays. This improved the photocatalytic performance under gamma rays treatment. Moreover, the PL quenching effect shows an improvement of photocatalytic properties.