Nanometer perovskite-type oxides MgTiO3,CaTiO3,SrTiO3 were prepared using tetrabutyl titanate,alkaline earth metal nitrates as raw materials by sol-gel method.The samples were characterized by thermogravimetry-differential thermal(TG-DTA),X-ray diffraction(XRD),UV-Vis spectrophotometer(UV-Vis)and X-ray photoelectron spectroscopy(XPS).Using methylene blue as a degradation target,we studied that calcination temperature had an impact on photocatalytic activity of three different photocatalysts.Through the photocatalytic degradation of methylene blue,photocatalytic activity of the three perovskite-type catalysts was compared.The results showed that different crystal structure resulted in different temperature of optimum activity.The temperature of best photocatalytic activity for MgTiO3 was 700 ℃,CaTiO3 and SrTiO3 were 800 ℃.In the above-mentioned catalyst,CaTiO3 had the highest photocatalytic activity.XPS analysis and catalytic reaction with O2 show that the surface oxygen absorbed capacity is the most important factor which has an influence on photocatalytic activity of three perovskite-type photocatalysts.
