Preparation and photocatalytic properties of nanometer TiO2 thin films by improved ultrasonic spray pyrolysis

The nitrogen-doped TiO2 thin films were prepared on glass substrate by an improved ultrasonic spray pyrolysis device with butyl titanate as the titanium source and ammonia as the nitrogen source. The surface morphology, crystal structure and optical properties of the resulting films were characterized by SEM, XRD and UV-VIS spectroscopy, respectively. The results show that N-doped TiO2 films have a more uniform and compact surface, the particle size trends to become smaller and then larger with the increasing amount of doping nitrogen. All the thin films belong to polycrystalline anatase structure and have a well visible light responsiveness with N doped. The photocatalytic activity and hydrophilic properties were investigated under ultraviolet irradiation. The degradation rate for methylene blue solution can reach 94.0% after 3 h under ultraviolet irradiation. The hydrophilic test shows that the hydrophilicity of TiO2 thin films can be improved by doping nitrogen to some extent.