Modification Of Bi₄Ti₃O₁₂ Based Photocatalyst And Its Degradation Performance

Photocatalytic technology uses solar energy as an energy source,and has advanced redox technology with important application prospects in environmental pollution treatment.It has become a research hotspot because of its advantages such as low cost and no secondary pollution.Among many catalysts,bismuth titanate has a variety of structural formulas and different spectral response ranges.In this paper,Bi₄Ti₃O₁₂ photocatalyst was prepared by solvothermal method and molten salt method,and its photocatalytic performance was systematically studied.The specific content is as follows:?1?Bi₄Ti₃O₁₂ photocatalyst was synthesized by solvothermal method using Bi?NO₃?₃·5H₂O and C₁₆H₃₆O₄Ti as raw materials,and then acidified by nitric acid to obtain acidified Bi₄Ti₃O₁₂ photocatalyst.Under photodegradation of RhB solution,tetracycline hydrochloride,and Cr?VI?solution,the photocatalytic activity of Bi₄Ti₃O₁₂ activated by nitric acid with a molar ratio of 1%is several times higher than that of Bi₄Ti₃O₁₂.Combined with XRD,HRTEM,XPS,solid UV-Vis absorption spectrum,transient photocurrent?I-T curve?and electrochemical impedance spectroscopy?EIS?,the defects of acidified Bi₄Ti₃O₁₂ were proved.Defective oxygen vacancies formed by nitric acid treatment play a vital role in improving the separation efficiency and transfer of photo-generated carriers.?2?In order to study whether the photocatalytic activity of Bi ₄Ti₃O₁₂photocatalysts prepared by different methods is the same,we use Bi?NO₃?₃·5H₂O and C₁₆H₃₆O₄Ti as raw materials,chloride as the molten salt,and anhydrous ethanol as the auxiliary method Bi₄Ti₃O₁₂ nanosheets were prepared.Combined with XRD,TEM,XPS and other tests,the crystal structure and morphology of the prepared samples were observed.The photodegradation of RhB solution,methylene blue solution and Cr?VI?solution proved the excellent photocatalytic activity of Bi₄Ti₃O₁₂ nanosheets prepared by this method.?3?In order to further improve the photocatalytic activity of Bi ₄Ti₃O₁₂prepared by sintering with molten salt method,we use Bi?NO₃?₃·5H₂O and C₁₆H₃₆O₄Ti as raw materials and use chloride as the molten salt to synthesize Bi₄Ti₃O₁₂/Bi₂Ti₂O₇ composite photocatalyst in one step.By adjusting the raw material ratio of bismuth nitrate pentahydrate and tetrabutyl titanate,th e relative amounts of Bi₄Ti₃O₁₂/Bi₂Ti₂O₇ were changed.The crystal phase structure of the prepared samples was characterized by XRD,SEM,TEM,DRS and so on.The photocatalytic activity of the composite is better than that of the monomers Bi₄Ti₃O₁₂ and Bi₂Ti₂O₇.The apparent degradation rate constants of the best composite are 3 and 2 times that of Bi₄Ti₃O₁₂ and Bi₂Ti₂O₇,respectively.I-T and EIS prove that the formation of heterogeneous combinations of composite photocatalysts improves the photocarrier transport and separation efficiency,thereby improving the photocatalytic activity.