Influence of preparation methods on the structure and catalytic performance of SnO2-doped TiO2 photocatalysts

The influence of preparation methods on the physicochemical and photocatalytic activity of Sn4+ doped TiO2 is mainly investigated in this work. Five different preparation methods have been used to synthesize SnO2-TiO2 catalysts: sol-gel method (SGM), sol-hydrothermal method (SHM), co-precipitation method (CM), coprecipitation-hydrothermal method (CHM) and hydrothermal method (HM). Their differences in the structures, chemical composition, particle sizes, specific areas, pore size distribution and energy band structure feature were characterized by XRD, XRF, FESEM, LRS, N2-physisorption and UV-vis DRS, respectively. Furthermore, the photocatalytic activity of the as-synthesized products was evaluated by monitoring the degradation of methyl blue (MB) solution under UV illumination. It is shown that the Ti0.75Sn0.25O2 catalyst prepared by the sol-hydrothermal method has the optimum catalytic activity for degradation MB, which is attributed to the optimal crystallization, homogeneous surface, uniform particles, good dispersibility and enhanced light absorption. Moreover, this is a novel method for the synthesis of SnO2-TiO2 photocatalyst firstly combining sol-gel and hydrothermal synthesis. Our findings demonstrate that the new way could be utilized in preparations of other catalysts for promising development of high-performance photocatalysts in the environmental applications.