Preparation Of Bismuth Vanadate Composite Photocatalysts And Study On Its Visible-Light Driven Photocatalytic Performance

In recent years,the use of photocatalytic technology to deal with environmental pollution has become the focus of the world.Among them,the use of photocatalysts to degrade organic contaminants has the advantages of being highly efficient and environmentally friendly,material availability,and lower maintenance cost,and is expected to be an ideal way to solve environmental pollution problems.Bismuth vanadate is a typical metal oxide.It has the characteristics of wide photoresponse range,low-carbon and environmentally-friendly and non-toxicity.It is widely used in the fields of photocatalysis and electrocatalysis.However,the drawbacks of the high recombination rate and low activity of photogenerated electron-holes in Bismuth vanadate limit its practical application in many fields.In order to improve the insufficiency of the vanadate bismuth material itself,a highly efficient and stable photocatalyst is developed.In this paper,Bismuth vanadate is used as the main body,and a heterojunction photocatalyst is constructed by compounding with other materials,and various characterization means and experimental methods are adopted.The structure characteristics,activity and reaction mechanism of the samples were discussed by various analytical and experimental methods.The thesis mainly includes the following cintents:?1?A one-step solvothermal method for the synthesis of RGO/Bi₄V₂O₁₁composite photocatalyst was proposed.Regulation by adding RGO of amount to inquire the effect in RGO/Bi₄V₂O₁₁ photocatalyst structure,and composite of the samples or the like can be charactered by X-ray diffraction?XRD?,and Raman analysis?Raman?.The activity of the prepared photocatalysts was performed.As a result,it was confirmed that after the introduction of RGO,the photocatalytic activity was significantly improved.Particularly,BR-4%sample has showed higher photocatalytic activity and stability than other samples,and the degradation rate for TC is 72.4%under visible light for 60 min.Finally,the mechanism of RGO/Bi₄V₂O₁₁ indicates that·OH and h⁺are active species participating in the system.?2?The CdS/Bi₄V₂O₁₁ heterojunction photocatalyst was designed and synthesized based on hydrothermal method and in-situ deposition method.The molar ratio between the two components of CdS/Bi₄V₂O₁₁ heterojunction photocatalyst was regulated by changing the amounts of cadmium acetate and thioacetamide.On this basis,the microstructure,composition and activity of the samples were analyzed by a series of characterization and photocatalytic experiments such as XRD,SEM,TEM,HRTEM etc,and the optimum ratio between the components was determined.The experimental results show that?3:1?-CdS/Bi₄V₂O₁₁ has the highest photocatalytic activity to different organic pollutants solution?including CIP,TC and RhB?,reaching76.97%,95.7%and 83.7%within 120 min respectively,and the stability is higher than other samples.The degradation reaction mechanism of CdS/Bi₄V₂O₁₁ confirms that·OH,h⁺and·O₂^-are the main active species in this system.?3?Bi/BiVO₄ photocatalysts were synthesized by co-precipitation and NaBH₄reduction method.By changing the concentration of NaBH₄ solution,the amount of reduced Bi nanoparticles was regulated.On the basis,the composition and microstructure of the Bi/BiVO₄ photocatalyst were explored by using XRD,XPS,SEM,TEM,HRTEM and other analytical methods.In addition,the activity of Bi/BiVO₄photocatalysts was performed by TC degradation under visible light.As a result,0.04-Bi/BiVO₄ showed the highest activity and good stability than other samples,and the degradation rate for TC solution up to 74.7%within 60 min.In addition,the results of photocatalytic degrading experiments,photocurrent and DRS analysis shows that the Bi nanoparticles in the Bi/BiVO₄ samples improve the separation efficiency of photogenerated electron-holes pairs.Finally,the reaction mechanism of the photocatalyst was determined by capture experiments and ESR analysis,and·OH and h⁺are the active species in this system.