Study On Synthesis And Photocatalytic Properties Of Double Perovskites A₂MnMoO₆（A=Ca,Sr,Ba） And Doped Compounds

Double perovskite compound,as a new type of inorganic material,which is similar to single perovskite compound,become the focus of many researchers due to its unique physical and chemical properties in the field of ceramics,electromagnetic field and catalytic fields.In this paper,A₂MnMoO₆（A=Ca,Sr,Ba）and La³⁺doped Sr_2-xLa_xMnMoO₆double perovskite photocatalytic materials are prepared by infrared-assisted sol gel method using citric acid as complexing agent.The pretreatment conditions and calcination temperature of the precursor are investigated by means of TG-DSC.Finally,the dry powder precursor is presintered at 600℃then calcined at 1000℃.The structure and surface morphology of catalysts have been characterized by XRD,IR,SEM and other instruments.The experimental results show that a series of double perovskite photocatalysts that have a single phase structure can be prepared by this method.Furthermore,the samples’surface morphology are regular,particle are clear without obvious agglomeration.This paper mainly explores photocatalytic properties of A₂MnMoO₆（A=Ca,Sr,Ba）in the visible light and A-site La³⁺dopant amount influenced on photocatalytic properties of Sr_2-xLa_xMnMoO₆.The dye wastewater is simulated by methyl orange solution.The degradation process of the dye under visible light is investigated by UV-Vis and DRS.The results proves that the band gap of Ca₂MnMoO₆,Sr₂MnMoO₆and Ba₂MnMoO₆ are 2.552 eV,2.448 eV and 2.940 eV respectively,they have high photocatalytic activities under visible light.The degradation rate of methyl orange solution are 69.76%,79.28%and 54.11%.In addition,compared to undoped Sr₂MnMoO₆,the band gap of Sr_2-xLa_xMnMoO₆ decreases,and the range of the light response is red shifted,which indicates that the photocatalytic activity of the catalyst in the visible region is increased after La³⁺doping.By observing the effect of doping amount on the photocatalytic activity,it is found that x is 0.4,the photocatalytic activity of the catalyst is the highest.