Fabrication And Photocatalytic Properties Of BiOX-based Composites

Industry is the main body and engine of economic growth,and its development promotes social progress.However,the pollution of water environment caused by industrial sewage is becoming more and more stern.Organic pollutants such as dyes and antibiotics in water environment have complex ingredients,strong poisonousness and poor biodegradability,and difficult purification.Photocatalysis technology can completely mineralize pollutants into H₂O and CO₂ under the excitation of light,which is a green and economic water treatment technology.Today,a large number of semiconductor materials have been used for photocatalytic degradation of pollutants.Bismuth halide oxide（BiOX）,as a typical photocatalytic material,has a unique layered structure,excellent chemical stability and controllable band gap,and has strong applied potential.In view of the above problems,this paper mainly takes BiOBr and Bi OCl as research objects and aims to improve the photogenic carrier transfer efficiency to prepare stable and efficient composite photocatalytic materials for degrading organic pollutants in wastewater.Main contents are as follows:（1）An efficient S-type AgBiO₃/BiOBr heterostructure was synthesized by hydrothermal method and in situ precipitation method.The degradation efficiency of ciprofloxacin under visible light irradiation was studied,and the relationship between the loading capacity of Ag Bi O₃ and the activity of photocatalytic material was discussed.The effects of pollutant concentration,catalyst dose,p H,impurity ions(PO₄^3-,HPO₄^2-,H₂PO₄^-)on photocatalytic activity were investigated.The results showed that the optimal proportion of AB5heterojunction showed excellent ciprofloxacin degradation performance within 120 minutes.The degradation efficiency of ciprofloxacin was up to 83%,which was 1.46 times and 4.15times of that of pure Ag Bi O₃ and BiOBr,respectively.The elevated photocatalytic behavior get benefited from the introduction of Ag Bi O₃,which not only improves the availability of visible light,but also forms the S-scheme heterojunction with valency band matching,which accelerates the segregation and divert of electron-hole,and heighten the redox capacity.（2）The oxygen-rich BiOBr was prepared by hydrothermal method,and the Z-type Ag₂WO₄/BiOBr heterojunction was constructed by in-situ precipitation.The effect of Ag₂WO₄loading on the photocatalytic performance of Ag₂WO₄/BiOBr heterojunction was investigated,and the influence of environmental factors on the photocatalytic degradation of Lanasol Red5B（LR5B）was investigated,and the reasons for the enhanced photocatalytic performance of AB-20 heterojunction were analyzed.According to the experimental results,the degradation rate of LR5B by AB-20 heterojunction is 98%within 15 minutes,which is 4.67 times that of BiOBr.The formation of oxygen vacancy and the construction of heterojunction have improved the visible light absorption performance of the photocatalyst,promoted interfacial charge separation and transfer,enhanced the redox performance,and thereby improving the photocatalytic performance of the photocatalyst.（3）AgCl/BiOCl composites were synthesized by water bath and hot stirring method.The structure,composition and morphology of Ag Cl/Bi OCl heterojunction were characterized by various analytical methods.Tetracycline hydrochloride（TC）was taken as the target of the study to evaluate the photocatalytic performance of the material under simulated sunsight.The influence of the loading capacity of Ag Cl on the photocatalytic activity of the photocatalyst was investigated,and the influence of TC concentration,p H and inorganic salts on the photocatalytic degradation activity of the material was explored.The experimental results proved that the optimal ratio of Ag Cl/Bi OCl composites showed the best degradation efficiency of TC with81.53%after 60 minutes of simulated sunsight irradiation,which was 1.66 and 2.15 times of pure Bi OCl and Ag Cl,respectively.The improvement of catalyst performance is attributed to the effective separation of photogenic charge,the good interfacial interaction between Ag Cl and Bi OCl and the construction of Z-type heterojunction.