Preparation And Photocatalytic Properties Of Transition Metal Polyoxides

Water is the source of life and is closely related to people’s production and life.Today,with the rapid development of global science and technology,the world’s production capacity is also growing rapidly,but this has also led to various water pollution problems,which make the wastewater treatment become an urgent issue.Solar photocatalytic technology has the characters of saving time and labor,high efficiency efficient,rational use of natural resources along with bring the pollution under control.Among the many photocatalysts,transition metal polyoxides have attracted much attention for their excellent photovoltaic properties and good stability,and create the good prospects for photocatalytic research.In this thesis,a series of composites based on transition metal polyoxides Bi₂WO₆ were prepared,and the photocatalytic properties of the products were investigated.The details research contents and results are as follows:（1）The g-C₃N₄/Bi₂WO₆ was synthesized by a solvothermal method,where g-C₃N₄was prepared by the high temperature solid state method,and then the 20 wt%Ag Br was loaded on the g-C₃N₄/Bi₂WO₆ by room temperature precipitation method to prepared the ternary Ag Br/g-C₃N₄/Bi₂WO₆ composites,which exhibited the excellent photocatalytic degradation to the anionic dye Congo Red（CR）and the cationic dye Rhodamine B（Rh B）.Due to the photosensitization of Ag Br,the photo-response range of the materials was greatly extended,and the formation of double Z-type heterojunctions between the semiconductors reduced the recombination efficiency of photogenerated carrier in the samples.（2）Flower spherical Bi₂WO₆ was prepared by solvothermal method,the binary Ag Cl/Bi₂WO₆ composite was obtained by room temperature precipitation method,and the Z-type heterojunction Ag/Ag Cl/Bi₂WO₆ photocatalysis was obtained the followed photo-reduction method.The catalyst exhibited the outstanding photocatalytic degradation to the cationic dye Rhodamine B（Rh B）and the anionic dye Congo Red（CR）under visible light irradiation.Moreover,it showed also the better degradations to methylene blue,methyl orange,tetracycline hydrochloride and norfloxacin.This results could be attributed to the flower spherical structure,the construction of the Z-shaped heterojunction and the plasmon resonance effect of Ag.（3）Using Bi₂WO₆ as the substrate,the Ag I/Bi₂WO₆ binary heterostructures with different Ag I doping amounts were prepared,and the photocatalytic degradations of the cationic dye Rhodamine B（Rh B）and the anionic dye Congo Red（CR）by the materials were tested.The photo-response range of the composites was broadened by the loading of Ag I,the photocatalytic activity was also improved,and the composites with 20 wt%Ag I doping showed the most excellent photocatalytic performance.The degradation efficiency of Rh B could reach to 90.8%in 20 min,and the degradation efficiency of CR could reached to 80.7%in 40 min,which were 8.6 and 9.5 times higher than those of pure Bi₂WO₆,respectively.