Influence of Zn doping on the photocatalytic property of SrTiO₃

 The Zn doped SrTiO₃ photocatalysts were synthesized and the photocatalytic activity of the doped samples for water decomposition to hydrogen was measured under the irradiation of a high pressure Hg lamp (400W). The influence of doping amount of Zn and the calcination temperature on the photocatalytic activity were investigated. The physical properties of catalysts with and without Zn doping were characterized using XRD, XPS, SEM and UV-visible diffuse reflectance spectra. The experimental results show that Zn doping greatly improves the photocatalytic activity of SrTiO₃. The optimum molar doping amount of Zn is about 1%, and in this case, the suitable calcination temperature is about 950℃. Under this condition, the photocatalytic property of Zn doped SrTiO₃ is 2.2 times higher than that of the undoped one. The characterization results indicate that 1% Zn doping does not change the crystal structure and crystal perfection properties of SrTiO₃. However, doping element Zn is enriched on the surface of SrTiO₃ sample. In addition, the crystal size increases within a certain range of Zn doping. It can be predicted that Zn2TiO₄ is generated by the incorporated Zn reacting with the Ti-rich phase existed on the SrTiO3 surface, which leads to the decrease of the surface defect concentration of SrTiO₃, and consequently increases the photocatalytic activity of Zn doped SrTiO₃.