Preparation Of Layer Bismuth-based Materials And Their Application In Environmental Catalysis

Under the rapid development of social economy and science and technology,the standard and quality of human life have been greatly improved,bringing environmental problems that are also getting more and more attention from human beings.The layered bismuth-based materials,characterized by[Bi₂O₂]²⁺sheets and interlaced anionic or and anionic groups forming a layered structure,have unique crystal structures,diverse compositions,rich atomic coordination and good hybridized electronic energy band structures,which have great potential for solar energy catalytic conversion.In this paper,a series of studies were conducted around the targeted conversion of carbon-based resources on metal oxide photocatalysts.Bi₂O₂Se and multivariate high-entropy bismuth-based materials were selected for modification and synthesis control for application in water environmental pollution treatment.The structure and elemental composition of the materials were determined by XRD and XPS,the morphology of the catalysts were observed by SEM and TEM,the full-spectrum light absorption ability and photothermal conversion efficiency of the materials were verified by DRS and thermal imaging,the separation and complexation of photocatalysts were analyzed by electrochemistry and spectroscopy,and finally the mechanism was inferred by the main active components.We successfully synthesized a super biosafety Bi₂O₂Se with crossed nanosheet structure（Bi₂O₂Se-CN）for the sterilization of Escherichia coli（E.coli）via solar-induced photothermal synergistic effect.In comparison to bulk Bi₂O₂Se,the lower light reflection and more efficient photogenerated charge carrier separation under visible-infrared light irradiation resulted in the excellent sterilization effect of Bi₂O₂Se-CN,with a sterilization efficiency of 99.9%under the synergistic effect of light and heat.The crossed ultrathin nanosheet structure and suitable band gap width of Bi₂O₂Se-CN are fundamental reasons for its enhanced light absorption and charge carrier separation efficiency.Mechanistic studies showed that Bi₂O₂Se-CN can completely inactivate bacteria via generating a large amount of reactive oxygen species（·O₂^-,·OH,and ¹O₂）to attack the cell membrane,which further resulted in the reduced activity of intracellular enzymes and the leakage of intracellular contents.The biosafety property of Bi₂O₂Se-CN was confirmed by in vivo toxicological evaluation on the mice model.The first high-entropy material Bi O[Cl Br I（CO₃）_0.5]solid solution was synthesized at room temperature using a one-step co-precipitation method.The number of anions in the anion layer was adjusted so as to adjust the band gap of Bi OX to a suitable value and enhance the photocatalytic reaction.The high entropy Bi O[Cl Br I（CO₃）_0.5]exhibited enhanced visible light response and higher photocatalytic activity in the degradation of methyl orange（MO）compared to the low and medium entropy Bi OCl,Bi O（Cl Br）and Bi O（Cl Br I）.Among them,Bi O[Cl Br I（CO₃）_0.5]had the highest photocatalytic activity and could completely degrade methyl orange within 15 min.The active species capture experiments confirmed that h⁺was the major active species and ¹O₂was the minor active species for the photocatalytic degradation of MO by Bi O[Cl Br I（CO₃）_0.5].