Hydrothermal And Solid-stat Synthesis,Modification And Photocatalytic Performance Of M（Ca,Zn）TiO₃

Perovskite-type photocatalyst (ABO3) becomes an active aspect in photocatalytic research field for its unique structure. When other metal ions partially substitute the A or B of ABO3, it is possible to form an ion defect or lead to the change of valency of B, thereby improving the performance of the photocatalytic. ABO3has been synthesized by solid-state processe, sol-gel processe and hydrothermal processe and so on. However, these methods can not meet the industrial requirements, such as low cost and low energy. Therefore, developing a new technique of ABO3is significant.In this paper, cheap TiO2was used as raw materials, starting from the lower calcinating temperature. CaTiO3and ZnTiO3were prepared by combination of hydrothermal processe and solid-state processe. A study was carried out about doping on the A site of CaTiO3. The synthesis, structure characteristics, doping improvements, photocatalytic performance were carried out systemically and in detail through test measures such as TGA-DTA (Thermogravimetry analysis-Differential Thermal Anylysis), XRD (X-ray radial diffraction), SEM (Scanning electron microscope), transmission electron microscopy (TEM) and UV-vis spectrometer. The main research contents and results are as follows:(1) The process of hydrothermal and solid-state method was studied to optimize the synthesis process of perovskite CaTiO3. The effect of calcination temperature and reaction time on the structure has been studied. The results show perovskite CaTiO3can be obtained by calcinated2h under500℃, CaTiO3was pure by calcinated10h under700℃. The results of SEM and TEM indicated the particle was about100nm. The formation mechanism and photocatalytic activity of CaTiO3was studied finally. The study of mechanism indicated titanate nanotubes exchanged with Ca2+ions first and then transferred to CaTiO3at high temperature.The degradation rate of methyl orange solution (15mg/L) reached95.5%over CaTiO3(0.3g/L) in20min under the irradiation of xenon light. The degradation kinetics follows first-order equation with0.1091of rate constant.(2) ZnTiO3was synthesized by hydrothermal and solid-state method. The effect of calcination temperature and reaction time on the structure has been studied.Results indicate the optimized condition of perovskite ZnTiO3was:the raw materials calcinated at800℃for10h. The SEM and TEM images showed that the particle was about100～500nm in width.The degradation rate of methyl orange solution (15mg/L) reached92.7%over ZnTiO3(0.3g/L) in20min under the irradiation of xenon light. The degradation kinetics follows first-order equation with0.1020of rate constant.(3) A study was carried out the degradation kinetics follows first-order equation with0.1091of rate constant on La and Ag doping on the B site of CaTiO3. XRD results show that La and Ag have been doped into Ca site of CaTiO3. It is found that La doping decrease the optical ability of CaTiO3, optical ability of CaTiO3is improved by doping Ag and the optimal doping amount was0.015with0.1638of rate constant.