Studies On The Preparation And Photocatalytic Activity Of Perovakite-type Oxides SrTiO₃

In order to improve the photocatalytic activity of SrTiO3 perovskite oxide under visible light,and to increase its degradation of weak biochemical dye wastewater,the preparation of SrTiO3 composite and the influence of Zr doping perovskite-type photocatalyst structure and properties were investigated.The analysis on the structure performance of the photocatalysts was obtained by different methods of characterization,as XRD,BET,SEM etc.The photocatalytic activity of the photocatalysts was studied by degrading methylene blue as the goal pollutant in photocatalytic reactor made by ourselves under visible light.First of all,SrTiO3 powders(SrTi-F,SrTi-S and SrTi-C)were prepared by three methods:fractional-precipitation method,sol-gel and coprecipitation.The samples obtained were characterized by UV-Vis spectroscopy,XRD,BET,SEM,TEM and EDX.The photocatalytic activity of degrading methylene blue was also studied under visible light.The results showed that SrTi-S and SrTi-C exhibited perovskite phase.Besides perovskite phase SrTi-F showed Sr2TiO4 crystalloid.Photocatalytic activity tests showed that the first-order reaction rate constants were 4.6 times higher than Degussa-P25 photocatalyst.Existence of impurity-crystalloid Sr2TiO4 was good for the conduction of electrons and holes,and improved the photocatalytic activity of SrTiO3.Secondly,nanophotocatalysts SrTi1-XZrXO3(x=0,0.2,0.3,0.4,0.5,0.8)were prepared by fractional-precipitation method.The structural features and photocatalysis performance of different x value samples were studied.The results showed that compared with SrTiO3 sample,the crystalling phase structure of SrTi0.5Zr0.5O3 sample had changed significantly.With the increase of x value,the crystalling phase structure of sample changed from SrTiO3 and Sr2Ti04 to SrZrO2 and SrO etc oxide crystalling phase.Compared with other samples,the sample of SrTio.5Zro.5O3 had smaller grain size,larger surface area,larger absorption strength of the visible light,and the highest photocatalytic activity.Photocatalytic activity tests showed that the first-order reaction rate constants of SrTi0.5Zr0.5O3 sample were 14.5 times higher than pure SrTi03 photocatalyst.The larger surface area and the higher adsorption properties of visible light can make photocatalysts produce more electronic and holes.In addition,mixed crystalling phase is propitious to the effective separation of electronic and holes.All of these can help photocatalysts improve the photocatalytic activity under visible light.The research shows that the best preparation of SrTiO3 photocatalyst is fractional-precipitation method,and adequately doping of Zr can effectively improve photocatalytic activity of SrTiO3 on degradation of methylene blue under visible light.It is a good application prospect.