Preparation Of Bi-based Materials For Visible-light-driven Photocatalytic Applications

Among the various new energy technologies and environmental pollution treatment technologies that support the future global sustainable development,the solar-light-driven photocatalytic technology is a green technology that can simultaneously solve energy depletion and environmental pollution.However,there are still some challenges in improving the conversion efficiency of solar energy,such as poor response of semiconductors to long-wavelength light,easy recombination of photo-generated electrons and holes,and easy photo-corrosion of catalysts.Dye sensitization is a promising method to solve the above problems.The improvement of dye sensitization performance mainly depends on the band gap energy（E_g）of the catalyst and the strong adsorption capacity for dyes.BiOX_xY_1-x（X,Y=Cl,Br,I）solid solution with continuously adjustable E_gis an ideal dye-sensitized carrier matrix.However,the BiOX_xY_1-x（X,Y=Cl,Br,I）solid solution currently reported in the literature has an unsatisfactory adsorption capacity for dyes,which affects the improvement of its photocatalytic performance.Aiming at the problem of poor dye adsorption capacity of BiOX_xY_1-x（X,Y=Cl,Br,I）solid solution,the main research work of this paper is as follows:（1）By chemical precipitation method,a series of 3D BiOBr_xI_1-xsolid solutions were synthesized at room temperature under the induction of ethylene glycol.The synthesized BiOBr_xI_1-xsolid solution exhibits better photocatalytic performance than BiOBr and BiOI under visible light degradation of rhodamine B（Rh B）,especially BiOBr_0.9I_0.1.We used a variety of testing instruments to characterize the synthesized BiOBr_xI_1-xsolid solution in terms of structure,morphology and size,and also conducted an in-depth analysis of the mechanism of its photocatalytic degradation of Rh B.（2）As we all know,Rh B is a dye sensitizer.Based on BiOBr_0.9I_0.1showing the best degradation performance on Rh B,in order to further improve the adsorption of BiOBr_0.9I_0.1on Rh B,we successfully synthesized a commercial bismuth oxide（Bi₂O₃）as a self-templating agent with a larger specific surface area and surface containing BiOBr_0.9I_0.1with more oxygen vacancies（OVs）.After UV-visible spectrophotometric detection,it was found that the adsorption rate of Rh B on the modified BiOBr_0.9I_0.1reached 46.56%,while the previous adsorption rate of BiOBr_0.9I_0.1on Rh B was only 28.35%.The modified BiOBr_0.9I_0.1and Rh B sensitized were used for visible light hydrolysis to produce hydrogen.The hydrogen production rate reached 33.5μmol g^-1h^-1,which was 27.9 times that of BiOBr_0.9I_0.1which was not sensitized by Rh B.In addition,when the p H of the solution was adjusted to 3,we found that the modified BiOBr_0.9I_0.1’s adsorption rate of Rh B increased to 79.77%,and the superoxide radical（·O₂^-）generated by the oxygen activation of the photocatalytic system was used.For the degradation of tetracycline hydrochloride（TCH）and methyl orange（MO）,the result shows excellent degradation performance.