Preparation and photocatalytic performance of Cs+/Sr2+-doped nano-sized TiO2

The un-doped TiO2 and Cs+/Sr2+-doped TiO2 nanometer particles were prepared by sol-gel method using tetrabutyl titanate (Ti(OC4H9)(4)) as TiO2 precursor, and characterized with X-ray diffraction (XRD) and UV-Vis absorption spectra (UV-Vis). The photocatalytic activities of these samples were investigated by the photocatalytic degradation of methyl orange in aqueous suspension under 300 W medium pressure mercury lamp irradiation. The results show that the growth of crystallite size can be controlled effectively for the Cs+/Sr2+-doped TiO2, and crystal phase transformation of nano-sized TiO2 is retarded from anatase structure to rutile structure while using the proper doping concentration of Cs+/Sr2+. It is pure anatase of high photocatalytic activity for Cs+/Sr2+-doped nano-sized TiO2 prepared at 600 degrees C for 2 h. The average crystal sizes of un-doped TiO2, 0.1% Cs+-doped TiO2 and 0.3% Sr2+-doped TiO2 are 21.3, 13.1 and 10.8 nm, respectively. Moreover, the doping TiO2 can extend the light response to the visible region at 400-600 nm. By measuring their photocatalytic degradation rate of methyl orange solution, the results indicate that Cs+/Sr2+ -doped TiO2 samples are found to improve photocatalytic degradation activity of TiO2 markedly, and the optimal doping concentration is determined to be 0.1% and 0.3% for Cs+ and Sr2+, respectively. Photocatalytic degradation rate of Cs/Sr-doped nano-sized TiO2 can be 15%-25% higher than that of un-doped TiO2 under the same condition.