Synthesise Of The Cd₂Sb₂O_6.8-Based Visible Light Photocatalysts And Their Photocatalytic Degradation Performances Of Rhodamine B

With the development of chemical industry,a variety of dyes have been widely applied in aspect of life.They are profoundly difficult to be degradeded thoroughly in the traditional wastewater treatment processes.Semiconductor photocatalytic technology,which can degrade organic pollutants in wastewater efficiently and completely under a mild condition,has a good application prospect.Due to its own defects,the traditional photocatalyst shows great disadvantages holding the features of low quantum yield,poor solar energy utilization and deactivation easily which limits greatly its practical application.Therefore the focus and hot spot of photocatalysis reasearch is to prepare for the other eco-friendly photocatalyst with high efficiency.Cd₂Sb₂O_6.8 is a kind of typical ternary semiconductor material,whose band gap is bigger than other materials（nearly 3.5 eV）.At the same time,Cd₂Sb₂O_6.8 has only photocatalytic activity in ultraviolet region due to posesses a narrow light response range.It is reported that pure Cd₂Sb₂O_6.8 nanoparticle can degrade benzene steam and dye under UV light irradiation The research results show that pure Cd₂Sb₂O_6.8 nanoparticles can degrade 150 mL(2×10^-5mol/L)RhB thoroughly within 60 min.But Cd₂Sb₂O_6.8 posesses lower mineralization rate.Apparently,its degradation ability is terrible and it is still ameliorated.In most semiconductor photocatalytic materials,BiOI and CdS photocatalysts exhibit excellent photocatalytic properties due to their special layered crystal structure and suitble band gap.Therefore,this research studied the composite materials of Cd₂Sb₂O_6.8 and BiOI or CdS,respectively.In this work,the scanning electron microscopy（SEM）,X-ray photoelectron spectroscopy（XPS）,transmission electron microscopy（TEM）,X-ray diffraction（XRD）and other related instruments are used to investigate the bulk phase,surface structure and morphology of the catalyst in detail.Subsequently,the optical response of the catalysts,catalytic degradation rate of dye,endocrine disrupting chemicals reduction rate and band structure are characterized by ultraviolet-visible diffuse reflection spectrum（UV-vis DRS）,photoluminescence spectra（PLand TA-PL）,ultraviolet-visible spectrophotometer,photocurrent（PC）and electrochemical impedance spectroscopy（EIS）.The main results and conclusion obtained from these studies are as follows:1.Using a solvothermal-chemical bath method,the BiOI/Cd₂Sb₂O_6.8 and CdS/Cd₂Sb₂O_6.8 composite catalyst have been prepared successfully.The analytical results by SEM,TEM and HRTEM show that Cd₂Sb₂O_6.8 nanoparticles have been uniformly distributed on the surface of BiOI nanoplates in BiOI/Cd₂Sb₂O_6.8 composite.And particle sizes are equably and its diameter is about 5-10 nm.In the CdS/Cd₂Sb₂O_6.8 composite,Cd₂Sb₂O_6.8 nanoparticles are contacted with CdS tightly and uniformly.It can be concluded that the absorption rang of light of two kinds of composite catalysts have been extended into visible light region by analysing the datas of DRS.2.In BiOI/Cd₂Sb₂O_6.8 composite catalyst,the adding amount of BiOI can influence composite catalyst crystal structure and activity.When adding amount of BiOI is 10 wt %,the composite catalyst photocatalytic activity can reach up to the highest point.3.In CdS/Cd₂Sb₂O_6.8 composite catalyst,the adding amount of CdS can also result in the important influence on composite catalyst crystal structure and activity.When adding amount of CdS is 10 wt%,the composite catalyst photocatalytic activity can reach up to the highest point.4.We make a research for studying the photocatalytic activity of Bi OI/Cd₂Sb₂O_6.8 and CdS/Cd₂Sb₂O_6.8 about the degradation of RhB（the concentration of RhB is 10 mg/L）.The results show that the two kinds of compound visible light catalyst for RhB degradation efficiency,compared with the pure Cd₂Sb₂O_6.8,pure BiOI and pure CdS,are enhanced significantly.BiOI/CSO-10 visible light catalyst can degrade RhB thoroughly within 180 min under visible light irradiation.Its photocatalytic efficiency is 100%.CdS/CSO-10 visible light catalyst can degrade RhB and its degradation efficiency can reach up to 99%.5.Combining with the band theory of semiconductor,the result of trapping agent test and test characterization results of the PC and EIS,We make a multiple analysis to reveal preliminary the transfer way of carrier in the photocatalytic reaction and explain the nature reason of the photocatalytic degradation of Rh B.At the same time,We put forward the possible degradation mechanism.