The Preparation Of Porous Visible Light Catalyst And Its Catalytic Performance

In recent years, photocatalytic oxidation process received wide attention in thepurification of the environmental pollution,because of its advantages of low energyconsumption, purification mild conditions, no secondary pollution, with thedevelopment of photocatalyst is an important part.Among a variety of visible lightactive photocatalyst researches, Bi2WO6is one of the most attractive materials, it isbecause of its high stability, non-toxic, light response of the extensive and goodphotocatalytic activity.The concrete content of this study includes the following two parts:(1)Monoclinic Bi2WO6with ordered mesoporous structurewas prepared by usingimpregnation method,bisumuth nitrate pentahydrate and sodium tungstate asmaterials,and the SBA-15(prepared by hydrothermal synthesis method) as template.The effects of the calcined temperature and time of Bi2WO6and SBA-15dosage onthe morphology and catalytic performance of porous Bi2WO6were also concerned.The study shows that the optimal preparation conditions of porous Bi2WO6are400℃calcination temperature and6h calcination time,0.3g of SBA-15dosage.The result ofphotocatalytic degradation of Rhodamine B solution shows that the photocatalyticdegradation rate of the Bi2WO6is66.61%,while the photocatalytic degradation rate ofthe same conditions of porous Bi2WO6is91.75%. The result of dynamics researchshows that the rate of porous Bi2WO6is2.26times of Bi2WO6without holes in thedegradation of Rhodamine B solution.(2)Mesoporous Bi2WO6(denoted by m-Bi2WO6) photocatalysts were prepared byhard template method.And then Ag loaded mesoporous Bi2WO6composites (denotedby Ag/m-Bi2WO6)were obtained by photoreduction method. The samples werecharacterized by N2adsorption-desorption,XRD,XPS and DRS techniques.Moreover,Rhodamine B was chosen as the model substance to evaluate thephotocatalytic activity of the photocatalysts. The results indicated that thephotocatalytic activity of mesoporous Bi2WO6can be enhanced by loading Ag on thesurface. And discuss the influence of the different Ag/m-Bi2WO6photocatalystdosage, initial concentration of the RhB and the RhB solution of different pH on thedegradation rate. Results show that the best dosage of photocatalyst is1g/L; Under the condition of neutral Ag/m-Bi2WO6showed good degradation of RhB.In summary,the reason that mesoporous Bi2WO6exhibit stronger photocatalyticproperties compared with Bi2WO6,was due to the construction of mesoporous stuctureimproves the specific surface area of Bi2WO6,increase the contact area of the lightcatalyst and pollutants,increase the surface reaction, at the same time light absorptionperformance has improved,thus improves the photocatalytic performance of theBi2WO6. Ag loaded on mesoporous Bi2WO6,formed a schottky junction on the surfaceof mesoporous Bi2WO6,it can improve the separation efficiency of light raw electronsand holes,in the end,improve the photocatalytic performance of mesoporous Bi2WO6.Therefore,construction of mesoporous microstructure and build heterojunction arepreferred methods to improve the photocatalytic performance of the photocatalysts.