Studies On Preparation Characteration And Photocatalytic Properties Of Crystal Induced BiVO₄/CdS Composite

In the current environment,the production and living of human society demand more and more energy,people's social activities on the environment caused more and more serious damage,the traditional way of access to energy can no longer meet people's needs,and the excessive development and utilization of traditional fossil energy produces a large number of pollutants,causing serious environmental damage.Environmental problems have threatened the environment on which human beings live and affect people's health.Semiconductor catalytic materials with sunlight as energy input can achieve photolysis of water to obtain hydrogen,reduce carbon dioxide and degradation of pollutants,not only can produce energy supply for production and daily use,but also can control pollution and reduce the pressure on the ecological environment.The huge application prospect of semiconductor materials photocatalysis technology has attracted the attention of many scholars.Bismuth vanadate and cadmium sulfide are two kinds of semiconductor materials which have good photoelectric conversion ability under visible light.They are widely used in photocatalysis.In this paper,decahedral monoclinic bismuth vanadate with crystal plane separation was prepared by hydrothermal method.Cadmium sulfide nanoparticles were deposited on{010}surface of bismuth vanadate by visible light irradiation induced by crystal plane of bismuth vanadate.The structure,photoelectric properties and photocatalytic properties of the composites were tested and analyzed.The main contents of this thesis are as follows:?1?The decahedral monoclinic bismuth vanadate with crystal plane separation was prepared by hydrothermal method,and the{010}surface of BiVO₄ photoelectron aggregation surface was electrostatically adsorbed to Cd²⁺,then reacted with S^2-to form CdS nanoparticles in situ.After high temperature heat treatment,BiVO₄ and CdS composite catalysts were obtained.The effect of{110}/{010}ratio on the photocatalytic properties of BiVO₄/CdS composites was further investigated by changing the pH value of the reaction solution during the preparation of BiVO₄,thus changing the morphology of BiVO₄ and adjusting the{110}/{010}ratio of crystal planes.The ratio of{110}/{010}crystal plane directly affects the amount of CdS deposited on BiVO₄,and ultimately affects the hydrogen production performance of BiVO₄/CdS composites.It was found that when the pH value of the reaction solution was 0.4,{110}was larger and{010}crystal plane was smaller,and the amount of CdS deposited was relatively small,so the photocatalytic properties of the composites decreased significantly.However,when the pH value of the reaction solution was 0.8,the exposed surface of BiVO₄ was incomplete,and CdS could not be induced to deposit,so the photocatalytic properties of the composites were not improved.When the pH value of the reaction solution is 0.6,the ratio of{110}to{010}crystal plane is more suitable,which makes the deposition amount of CdS on{010}crystal plane appropriate,so the photoelectric conversion efficiency and photocatalytic hydrogen production performance of the prepared BiVO₄/CdS composite are better than the former two.?2?Based on the above studies,the morphology,photoelectric properties,photocatalytic hydrogen production and photocatalytic mechanism of BiVO₄ and CdS composites prepared at pH=0.6 were studied by XRD,XPS,SEM,UV-Vis DRS and PL.According to the photoelectric characterization of the material,the prepared BiVO₄/CdS composite is a Z-scheme heterojunction structure.The effect of CdS input on the photocatalytic hydrogen production performance of BiVO₄/CdS composites was also investigated in this paper.The results showed that when the amount of BiVO₄ was500 mg?1.54 mmol?and the amount of CdS input was 1.75 mmol,the hydrogen production rate of the composites was 7.8 times as high as that of CdS samples,and no light induced crystal surface.The effect was 5.5 times less than that of the reference sample.