Preparation, Characterization And Photocatalytic Properties Of Perovskite-Type Nano-Materials Titanate And Bismuth Vanadate

This paper were committed to study preparation, characterization and photocatalytic properties of nanometer perovskite oxide A(Mg, Ca, Sr)TiO3 and another visible-light photocatalyst vanadate bismuth.Firstly, Nanometer perovskite-type oxides MgTiO3, CaTiO3, SrTiO3 were prepared 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). Through the photocatalytic degradation of methylene blue and TCE, photocatalytic activity of the three perovskite-type catalysts was compared. The results showed that different atoms at A metal lead to different crystal structure, and 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. The reason was that CaTiO3 photocatalyst had a greater ability of surface adsorbed oxygen, which provided more surface active species.Secondly, a single crystalline phase monoclinic scheelite type BiVO4 was prepared using Bi(NO3)3·5H2O and NH4VO3 as raw materials by water-phase precipitation method at different calcination temperature. Using methylene blue as a degradation target, we studied that calcination temperature had an impact on visible-light photocatalytic activity of samples. At the same time, molten salt-assisted method was tried to prepare monoclinic BiVO4 to enhance its photocatalytic activity in visible light. The results showed that a single crystalline phase monoclinic scheelite-type BiVO4 was successfully prepared at different calcination temperature(300℃,400℃, 500℃,600℃). The visible-light photocatalytic activity of sample obtained at 400℃was optima. The photocatalytic activity of monoclinic scheelite-type BiVO4 obtained by molten salt-assisted method had been obviously improved, and the amount of molten salt had a significant impact on visible-light photocatalytic activity of BiVO4.Thirdly, single crystalline tetragonal scheelite type BiVO4 and monoclinic scheelite type BiVO4 were prepared using Bi(NO3)3·5H2O and NH4VO3 as raw materials by water-phase precipitation method at low temperature. We studied that pH had an impact on visible-light photocatalytic activity of samples. The results showed that the tetragonal scheelite-type BiVO4 can be obtained by water-phase precipitation method at room temperature, and the monoclinic scheelite-type BiVO4 can be prepared at 110℃. pH had an impact on the crystalline of samples in the low-temperature synthesis process, and neither too acid nor too alkaline conditions are conducive to the formation of monoclinic phase. In the samples prepared at 110℃under different pH, the photocatalytic activity of sample under pH=7 was the highest. The reason was that it had smaller grain size and greater ability of surface adsorbed oxygen.It provides a certain theoretical foundation for the role of A metal in ABO3 perovskite structure photocatalyst by studying structure and photocatalytic properties of perovskite-type oxides A (Mg, Ca, Sr) TiO3. Simultaneously, preparation condition of high visible-light activity BiVO4 at low temperature is optimized, and the application path of BiVO4 material is also developed. The paper lays a stone for expanding research of visible light photocatalyst and utilization of green light source-solar energy.