Effect of ultraviolet irradiation on crystallization behavior and surface microstructure of titania in the sol–gel process

Nanosized titania was prepared at various hydrolysis ratios (r=H2O/Ti) by photo-assisted and conventional sol–gel methods. It was found that hydrolysis ratio and ultraviolet irradiation greatly affect the titania crystallization behavior. The introduction of photo-irradiation benefits anatase formation throughout a wide range of hydrolysis ratio. XPS results show that hydrolysis reaction was promoted by ultraviolet irradiation. In addition, photo-irradiation was also verified to be in favor of the generation of large specific surface area and high crystallinity, which resulted in relative high photocatalytic activity of TiO2 prepared by a photo-assisted sol–gel method.