F/d Mental Doped Functional Bi₂WO₆ Composites: Design, Synthesis, Characterization And Its Degradation Of Methylene Blue

In this thesis,Bi₂WO₆ was modified by doping with lanthanide element Eu,actinide element uranium and V₂O₅.The as-prepared products were characterized by X-ray diffraction（PXRD）,UV-vis diffuse reflectance spectra（UV-vis）,infrared spectrum（IR）,scanning electron microscopy（SEM）,energy dispersive X-ray spectrometry（EDX）,fluorescence,photoluminescence（PL）and BET analysis.The photocatalytical activity was investigated by a self-made optical reaction device in order to find the optimal doping ratio of the catalyst,so that a high photocatalytic performance of Bi₂WO₆ composite material was prepared.Using Bi（NO₃）₃·5H₂O and Na₂WO₄·2H₂O as raw materials,hydrothermal synthesis methods assisted by different amount of Eu were adopted to prepare Eu/Bi₂WO₆ composites with different morphologies.The as-prepared products were characterized by X-ray diffraction（PXRD）,UV-vis diffuse reflectance spectra（UV-vis）,scanning electron microscopy（SEM）,fluorescence and the photocatalytical activity tests.The result showed that Eu doping could improve the photocatalytic activities.Interestingly,the degradation rate increased with the increase of Eu content when the concentration was lower than 5%,however,as the Eu concentration further increased,the photocatalytic activity decreased.Therefore,the optimal Eu doping ratio was 5%.A novel 3D flower-like morphology of U/Bi₂WO₆ composite was successfully synthesized by the hydrothermal method assisted by sodium dodecyl sulfate（SDS）using Bi（NO₃）₃.5H₂O,Na₂WO₄.2H₂O and UO₂（CH₃COO）₂·2H₂O as precursors.The sample was characterized by X-ray diffraction（PXRD）,scanning electron microscopy（SEM）,energy dispersive X-ray spectrometry（EDX）,UV-vis diffuse reflectance spectra,photoluminescence（PL）spectra,BET and the photocatalytical activity tests including visible light induced and UV light induced photocatalytic experiences.In addition,the growth process of 3D hierarchical flower-like U/Bi₂WO₆ composite and its photocatalytic mechanism were also discussed.The shape of as-prepared product presented a good flower-like particle,and a higher photocatalytic activity of the sample was found which methylene blue（MB）could be completely degradated in 50 min under visible light irradiation and in 30 min under UV light irradiation.So the optimal U/W ratio was 4%.Using Na₂WO₄·2H₂O,Bi（NO₃）₃·5H₂O and V₂O₅ as precursors,the nest-like V₂O₅/Bi₂WO₆ composite was successfully synthesized when the V₂O₅ doping ratio was 16%by the hydrothermal method.The as-product was characterized by X-ray diffraction（PXRD）,scanning electron microscopy（SEM）,UV-vis diffuse reflectance spectra and BET analysis.The different doping amount of V₂O₅ was studied in this chapter.The result revealed that the nest-like V₂O₅/Bi₂WO₆ composite possessed a higher photocatalytic activity which methylene blue（MB）can be completely degradated in 6 min under visible light irradiation.In addition,we also investigated the effect factors of photocatalytic activities including the different amount of nest-like V₂O₅/Bi₂WO₆ composite and MB concentration.The result revealed that the nest-like V₂O₅/Bi₂WO₆ composite had a higher photocatalytic activity when the amount of nest-like V₂O₅/Bi₂WO₆ composite was 0.1g and the concentration of MB was 10mg/L.