Preparation And Photocatalytic Activity Of Bi (subscript 6) 6 Photocatalyst

Photocatalytic technology is an important aspect of oxidatively degrading andmineralizing organic pollutants in the environment applications. Becausephotocatalytic semiconducting mateirals have a strong oxidizing ability of degrading avariety of toxic and hazardous organic pollutants, and it utilizes the solar energy withlow cost, it has an extremely broad application petential. However, TiO〗 has a wideband gap, reduces the utilization of sunlight, and the quantum efficiency is low. Inorder to develop an alternative non-TiC^photocatalyst utilizing sunlight, this paperaims to develop a visible-light-responsed photocatalyst which has a controllablestructure.Bismuth-based photocatalysts are sensitive in the visible light region since theirband gap are narrow resulted from the hybird of Bi6S and〇2P orbitals, so that it can beexcited by visible light and applied to the ifeld of photocatalysis. Bismuth tungstate isa composite multilayered structure, and Bi2W06is the simplest one among Auirvilliusfamily. Vairous methods for the synthesis of Bi2W06have been developed includingsolid-phase method, hydrothermal method and solvothermal method. However, thesecatalysts only absorpt the light in the limited visible light region，and the separationeiffciency of photo-generated electron-hole pairs is low, not conducive to improvingthe photocatalytic activity. In view of the improvement of the environment and makebetter use of solar energy, it is still in need of further development of Bi2W06-basedcomposite photocatalysts which have a wider range of visible light response andhigher photocatalytic activity. In this paper, an ionic liquid assisted solvothermalprocess in glycol-ethanol system has been developed to synthesize the photocatalystswith controllable morphologies and high surface area. Furthermore, the relationshipsbetween catalyst structure and catalysis performance are discussed in detail. The mainworks are listed as following:1. Ionic liquid-assisted solvothermal synthesis of highly active Bi2W06photocatalystand its photocatalytic activity Highly active Bi2W06has been synthesized by using ionic liquid. In theglycol-ethanol system,[Cn-mim]BF4(n=2，4，8，16) ionic liquid acts asstructure-directing agent. Bi2W06with hollow microspheres presents the greatlyenhanced light absorption, and improves the photocatalytic activity. By changing thesovolthermal time, the amount of ionic liquid and alkyl chain length of ionic liquid,the optimal reaction conditions during the photocatalytic degradation of rhodamine Borganic pollutants as a probe has been demonstrated as20h,15ul and [C^mim] BF4.2.Ag/Bi2W06prepared by photo-reduction method and its photocatalytic activityAg nanoparticles supported on the surface of Bi2W〇6enhances the absorptionof visible light and improves the separation eiffciency of the eanrer via plasmaresonance effect. Ag/Bi2W〇6catalyst with0.75mol%Ag/Bi and photo-reduction timeof20min has been confirmed as the best photocatalytic activity.3.Ag/Bi2W06prepared by ultrasound-assisted photo-reduction method and itsphotocatalytic activityWe utilize ultrasonic-photoreduction synergistic mechanism to convert A+g intometallic Ag. The result shows that the effect of ultrasonic-photoreduction synergisticmechanism helps to improve the content of Ag and enhance the absorption in thevisible light region. The recombination probability of photogenerated carriers is low,and the mineralization eiffciency of organics is increased. This technology expandsthe preparation process method of photocatalyst with a perfect prospect.