Abstract: The nanocrystalline TiO2 with different crystal structures were prepared by sol-gel method at different temperatures.The crystal structure, morphology, element composition and chemical state of the samples were analyzed by XRD, SEM, EDS and XPS, respectively.The results show that TiO2 form anatase crystal structure at the temperature of 400 ℃ and 500 ℃, form anatase / rutile mixed crystal structure at the temperature of 600 ℃, and form rutile crystal structure at the temperature of 700 ℃.The single particle presents approximate spherical morphology.The rhodamine B was employed as the target pollutant to evaluate the photocatalytic activity of the samples.The results reveal that TiO2 which is annealed at 400 ℃ shows the highest photocatalytic activity and reaction rate constant.The degradation rate and the reaction rate constant are 94.6; and 0.969 h-1 after illumination for 3 h.

Key words: The nanocrystalline TiO2 with different crystal structures were prepared by sol-gel method at different temperatures.The crystal structure, morphology, element composition and chemical state of the samples were analyzed by XRD, SEM, EDS and XPS, respectively.The results show that TiO2 form anatase crystal structure at the temperature of 400 ℃ and 500 ℃, form anatase / rutile mixed crystal structure at the temperature of 600 ℃, and form rutile crystal structure at the temperature of 700 ℃.The single particle presents approximate spherical morphology.The rhodamine B was employed as the target pollutant to evaluate the photocatalytic activity of the samples.The results reveal that TiO2 which is annealed at 400 ℃ shows the highest photocatalytic activity and reaction rate constant.The degradation rate and the reaction rate constant are 94.6; and 0.969 h-1 after illumination for 3 h.