Construction Of Bismuth Tungstate-based Heterojunctions And Their Photocatalytic Properties Study

Though the high-speed development of science and technology has brought a lot of convenience to people’s lives,it also lead a number of new problems that threaten the environment,such as energy source shortage and environment pollution.Therefore,it is imperative to develop sustainable development methods to solve environmental problems and efficient energy storage devices.As a green method for the sake of environmental applications,photocatalytic technology has been widely investigated in recent decades.Up to now,many researches have proved that photocatalytic technology can convert organic pollutants in water into non-toxic and non polluting substances.However,there are some limited factors of most of photocatalysts,such as conduction and valence band position of the semiconductors,poor charge carrier transport.In this paper,Bi₂WO₆ has been chosen as the research material,and the aim was improvement of its photocatalytic properties by combining with other semiconductor and loading noble metal.The main works were listed below:（1）2D BWO/CN heterojunction photocatalyst was synthesized by hydrothermal method and high temperature calcination method.Photocatalytic activity was studied by degradation of RhB under visible light.The results showed that the photocatalytic activity of the heterojunction photocatalyst exhibited the best photocatalytic activity when the mass ratio of g-C₃N₄ to Bi₂WO₆ was 1: 0.67,and the degradation ability was three and two times that of the pure phase g-C₃N₄ and Bi₂WO₆,respectively.The heterojunction photocatalyst also had good degradation effect on TC and CIP.The mechanism of the photocatalytic process was discussed based on the active species trapping experiments and ESR.In the process of the degradation of RhB,·OH、·O₂^-and the hole played the major roles.（2）CNQDs/BWO composite photocatalysts were prepared by a simple hydrothermal method.Photocatalytic activity was studied by degradation of TC under visible light.The results showed that the degradation efficiency of CNQDs/BWO was2 times higher than that of pure phase BWO.The photodegradation mechanism was analyzed by photoluminescence.The presence of CNQDs accelerated the separation of photogenerated carriers and suppressed the recombination,which enhanced the photocatalytic activity.（3）Ag/Bi₂WO₆ composite photocatalyst was prepared by hydrothermal method and chemical deposition method,and the size of Ag nanoparticles was changed by adjusting the pH value of NaOH solution by controlling the amount of NaOH.Photocatalytic activity was studied by degradation of TC under visible light.The results showed that the degradation efficiency of Ag/Bi₂WO₆ was 2 times that of pure phase Bi₂WO₆.Electron spin resonance analysis shows that O₂^-plays a major role in the degradation of tetracycline,and ·OH,which is converted from it,plays a secondary role.