Fabrication Of Bi₂WO₆ And Its Composites For The Degradation Of Organic Dye

With the rapid development of human society and the accelerating process of industrialization,more and more household garbage and industrial waste water are generated.If discharged directly without treatment,it will cause serious damage to the ecological environment and affect people’s quality of life.Therefore,the treatment of wastewater has always been one of the hot topics of scholars at home and abroad.Photocatalytic technology,as an effective means to deal with environmental pollution and solve energy shortage,has been widely used in sewage treatment due to its advantages of economic efficiency and green environmental protection.Thus,it has become a focus to seek and develop suitable photocatalyst.In recent years,bismuth series semiconductors have been active in this field owing to its unique structure and excellent performance.Bi₂WO₆ has been widely studied because of its narrow band gap,low cost and high stability.However,Bi₂WO₆,like most semiconductor photocatalysts,has low quantum efficiency when used alone and low utilization rate of solar energy,which greatly limits its application in the degradation of organic compounds in wastewater.In this paper,Bi₂WO₆ was optimized and modified by means of morphological regulation and heterojunction construction,and the synthetic samples were characterized to explore their photodegradation performance of organic dyes under visible light irradiation.The main work contents and results were as follows.1.Four kinds of Bi₂WO₆ were successfully prepared by hydrothermal method using four different solvents.The Scanning Electron Microscopy（SEM）results showed that the four kinds of Bi₂WO₆ had different morphologies.Thus,by changing the solvent,the morphology of Bi₂WO₆ could be controlled and Bi₂WO₆ with high photocatalytic activity could be obtained.Meanwhile,the prepared Bi₂WO₆ was characterized by X-Ray Diffraction（XRD）,X-Ray Photoelectron Spectroscopy（XPS）,UV-vis Dissfuser Reflectance Spectrum（UV-vis DRS）,Photoluminescence spectra（PL）,etc.,and Rhodamine B（RhB）and Congo red（CR）were selected as the target organic pollutants for photocatalytic degradation experiment.The results showed that the photocatalytic activity of Bi₂WO₆ synthesized with ethylene glycol and dilute nitric acid as the solvent was almost the same,while the photocatalytic degradation effect of Bi₂WO₆ synthesized with acetone and the mixture of glacial acid and water as the solvent was significantly weaker than the former two,Bi₂WO₆ synthesized with acetone was the worst.2.3D flower-like BiPO₄/Bi₂WO₆ n-n homogeneity heterojunction was successfully synthesised via hydrothermal method,and the influence of BiPO₄ on the morphology,optical properties and photocatalytic properties of the composite photocatalyst was investigated.The results showed that BiPO₄ was successfully loaded on the surface of Bi₂WO₆,and BiPO₄ did not change the morphology of Bi₂WO₆.BiPO₄/Bi₂WO₆composite photocatalyst had a good photocatalytic activity against RhB under visible light irradiation.When the content of BiPO₄ was 15%,the composite photocatalyst has the best photocatalytic activity,about 1.4 and 3.7 times that of pure Bi₂WO₆ and BiPO₄.The improvement of photocatalytic performance was primarily ascribed to the synergistic effect between BiPO₄ and Bi₂WO₆,which promoted the separation of photo-generated electrons and holes.The results of three photocatalytic cycle experiments on the same sample showed that 15%BPO/BWO composite photocatalyst had excellent stability.