Preparation Of BiOBr-based Photocatalyst And Degradation Of Organic Dyes

As a large printing and dyeing industry,China should pay attention to the pollution control of organic dyes.At present,the organic dye pollutant treatment technology also has various degrees of shortcomings,such as physical method,biological method,chemical method and other methods.Among them,the photocatalytic technology in chemical method has entered people’s vision with the advantages of high efficiency,complete degradation,low energy consumption and simple operation,which fully embodies the environmental protection concept of sustainable and full utilization of clean energy-solar energy.Among them,Bi OBr has become a research hotspot due to its excellent photocatalytic ability.In this paper,the preparation and characterization of Bi OBr photocatalyst and its modified products,photocatalytic performance testing,photocatalytic mechanism and so on were discussed.The conclusions are as follows:（1）Bi OBr thin sections were prepared by hydrothermal synthesis method.Characterization showed that Bi OBr thin sections had certain photochemical activity,but had weak absorption to visible region and high electron-hole composite rate.The actual degradation rate after 60 min of photocatalysis was 57.9%.Bi OBr has good modification potential,among which ion doping and semiconductor compound are more efficient modification methods.（2）Bi OBr:Ag⁺photocatalyst was prepared by Ag⁺doping.It was found that The Bi OBr:Ag⁺photocatalyst showed a three-dimensional morphology of flower spheres with a large surface area.Ag⁺doping effectively improves the separation and transmission efficiency of photogenic carriers.After 60 min of photocatalysis,the degradation rate of Bi OBr:Ag⁺to MB was up to 85.9%,indicating that ion doping could indeed improve the photocatalytic performance of Bi OBr.However,the experimental conditions are still slightly harsh,which is not consistent with the concept of environmental protection and resource conservation.（3）Bi OBr and g-C₃N₄ were combined modified Bi OBr,and Bi OBr/g-C₃N₄composite photocatalyst was prepared by hydrothermal method.Characterization showed that in the Bi OBr/g-C₃N₄ composite catalyst,Bi OBr flake nanoparticles were evenly distributed on the g-C₃N₄ flake,forming a heterogeneous structure and effectively improving the separation and transmission efficiency of photogenic carriers.After 60 min of photocatalysis,the Rh B degradation rate of Bi OBr/g-C₃N₄was up to 72.9%,and showed high stability.Under the same conditions,Bi OBr/g-C₃N₄ also had good degradation effect on other organic dyes.The results show that the composite semiconductor method can improve the photocatalytic performance of Bi OBr.However,the catalytic activity of the modified composite photocatalyst needs to be further improved.（4）Bi₂₄O₃₁Br₁₀ nanometer tablets were prepared by microwave method,and the characterization showed that Bi₂₄O₃₁Br₁₀ nanometer tablets had greater crimp degree and increased specific surface area than Bi OBr nanometer tablets.Eg is 2.68 e V slightly lower than Bi OBr,and other photochemical properties are similar to Bi OBr.Under the same conditions as Bi OBr photocatalytic experiment,the actual degradation rate of AF after 60 min photocatalytic was 68.2%,higher than that of Bi OBr.This indicates that the Bi rich technology can improve the photocatalytic activity of Bi OBr,and Bi₂₄O₃₁Br₁₀ inherits the good modification potential of Bi OBr.（5）CeO₂/Bi₂₄O₃₁Br₁₀ composite semiconductor was prepared by in situ precipitation method.The characterization results showed that CeO₂ nanorods were evenly distributed on the surface of Bi₂₄O₃₁Br₁₀ nanorods,forming a Z-shaped heterostructure.After recombination with CeO₂,the intrinsic absorption edge of Bi₂₄O₃₁Br₁₀ is redshifted,which enhances the response intensity of Bi₂₄O₃₁Br₁₀ to visible light,reduces Eg（1.96 e V）,enhances the absorption capacity of Bi₂₄O₃₁Br₁₀ to visible light,reduces the electron-hole pair recombination rate,and effectively inhibits the strong adsorption of Bi₂₄O₃₁Br₁₀ and improves the photocatalytic efficiency.CeO₂/Bi₂₄O₃₁Br₁₀ composite semiconductor has degradation effect on a variety of dyes,among which the degradation rate of AF reached 97.6%after 60 min of light,and AF was degraded into H₂O and CO₂,avoiding secondary pollution.After repeated use for 4 times,the degradation rate of CeO₂/Bi₂₄O₃₁Br₁₀ composite photocatalyst to AF was still as high as 91.7%after 60 min of photocatalysis.The results of the active species capture experiment showed that the main active species of CeO₂/Bi₂₄O₃₁Br₁₀photocatalytic degradation of AF was·O₂^-.Interestingly,in the active species capture experiment,it was found that the catalytic effect of photocatalyst in the photocatalytic system with Ag⁺capture agent was higher than that in the blank group,and the CeO₂/Bi₂₄O₃₁Br₁₀ composite photocatalyst showed metallic luster on the surface.（6）Ag-CeO₂/Bi₂₄O₃₁Br₁₀ photocatalyst was prepared by depositing Ag on CeO₂/Bi₂₄O₃₁Br₁₀ nanocomposite semiconductor by redox method.The characterization results showed that the morphology of Ag-CeO₂/Bi₂₄O₃₁Br₁₀photocatalyst was similar to that of CeO₂/Bi₂₄O₃₁Br₁₀ nanocomposite semiconductor.After Ag deposition,the intrinsic absorption edge of photocatalyst was redshifted,which enhanced the response intensity of Bi₂₄O₃₁Br₁₀ to visible light,and effectively improved the separation and transmission efficiency of photogenic carriers.The degradation rate of AF by Ag-CeO₂/Bi₂₄O₃₁Br₁₀ photocatalyst reached 98.2%after 60min of illumination,showing a better photocatalytic performance than CeO₂/Bi₂₄O₃₁Br₁₀.（7）The CeO₂/Bi₂₄O₃₁Br₁₀/GO photocatalyst was prepared by in situ growth method and supported by CeO₂/Bi₂₄O₃₁Br₁₀.The characterization results showed that CeO₂/Bi₂₄O₃₁Br₁₀ nanocomposite semiconductor grew on the GO surface,which increased the specific surface area of CeO₂/Bi₂₄O₃₁Br₁₀/GO photocatalyst,providing more reactive sites for photocatalytic reaction.When GO is loaded with CeO₂/Bi₂₄O₃₁Br₁₀,the intrinsic absorption edge of the photocatalyst is redshifted,which enhances the response intensity of CeO₂/Bi₂₄O₃₁Br₁₀ to visible light,and effectively improves the separation and transmission efficiency of photo-generated carriers.The photocatalytic degradation rate of CeO₂/Bi₂₄O₃₁Br₁₀/GO reached 98.6%after 60 min of illumination under the photocatalytic experimental condition of half catalyst dose,showing a superior photocatalytic performance compared with CeO₂/Bi₂₄O₃₁Br₁₀.