| With the proliferation of economic and information,environmental problems are becoming increasingly serious.Water pollution,one of the most important problems in the world,has attracted wide attention.Researchers have been seeking an effective way to solve this problem efficiently,affordably and green,until photocatalytic technology being noticed.Semiconductor materials directly converts light energy into chemical energy,for the degradation of organic pollutants in air and water,and does not cause the secondary pollution,is considered to be a great treatment for the development of environmental protection.Bi2WO6,as a typical Bi-based photocatalytic materials,is a new type of photocatalyst.It is a kind of photocatalyst with visible light response,good photocatalytic ability and no photo-corrosion phenomenon.But the disadvantages of Bi2WO6 are also obvious:the short life of photogenerated electrons and holes,the large rate of surface recombination probability,which greatly affect the photocatalytic activity.In this study,we prepared a new efficient Bi2MOxWi1-xO6 solid solution catalyst,used Rhodamine B as the target pollutants,has been used to evaluate the catalytic's activity under the visible light.Through XRD,SEM,EDS,XPS,BET and other characterization techniques are show the surface characteristics of the crystal structure,morphology respectively,and the optical characteristics of the catalysts is tested by UV-Vis DRS.Finally,the photocatalytic mechanism was discussed.The main contents of this paper are as follows:1.The Bi2MoxW1-xO6 visible-light catalyst was prepared by one step hydrothermal method.The effect of precursor pH on the morphology and properties of the catalyst was investigated on the basis of the optimum Mo/W ratio.The results show that the current drive pH=5,Bi2Mo0.25W0.75O6 photocatalyst was obtained,showing the self-assembled flower like structure formed by nano particles.The structure has a larger surface area(24.834m2/g).Looking through the UV-Vis DRS test,the new photocatalyst has good response in the visible light range and the band gap is about 2.63eV,which can effectively utilize the visible light2.degradation of organic pollutants.Within 120min,the degradation rate of Rhodamine B can reaches 86.2%,The reaction kinetic of Rhodamine B degradation was according with pseudo-first orderreaction kinetic model.,the reaction rate constant is about four times of pure Bi2MoO6.After five cycles,it was found that the new Bi2Mo0.25W0.75O6 visible light catalyst has good chemical stability.3.On the basis of the preparation of Bi2Mo0.25W0.75O6 photocatalyst,Bi2O3 composite method was selected to improve the photocatalytic activity.By adjusting the molar ratio of Bi/W/Mo in the precursor solution of hydrothermal reaction,to control the content of the Bi2O3 on composite catalysts.After calcination,Bi2O3-Bi2Mo0.25W0.75O6 catalyst is obtained with good crystallization.It is found that when the mole ratio of Bi2O3 and Bi2Mo0.25W0.75O6 is 1:3,it obtains the best photocatalytic efficiency.By adjusting the calcination temperature found when the temperature is too high(T = 600?),the catalyst structure would be destroyed,flower shaped structure collapse rupture,nanosheets reunion,specific surface area decreased,so,the selection of the best calcination temperature is 400?.3.To explore the reaction mechanism of Bi2O3-Bi2Mo0.25W0.75O6 photocatalyst,the main reason increased photocatalytic activity is that the existence of Bi2O3 composite is conducive to the separation of photogenerated electrons and holes,it also inhibit recombination on the catalyst surface and realizes stable charge separation.4.By changing the initial concentration and pH of the Rhodamine B organic wastewater as well as changing the target pollutants to methylene blue to test the catalytic activity of this new kind of Bi2O3-Bi2Mo0.25W0.75O6 catalyst.It is proved that the new photocatalyst has good photocatalytic activity of methylene blue.This means the photocatalyst has a wide rage of degradation organic pollutants. |
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