Preparation And Visible Light Photocatalytic Performance Of All Inorganic Halogen Perovskite Photocatalyst

All-inorganic halide perovskite nanocrystals Cs Pb X₃?X=I,Br,Cl?has attracted more and more attention in recent years,and due to its longer carrier lifetime,higher photoluminescence quantum yield,and defect density Low,large band gap,good emission spectrum tunability,low cost,simple synthesis,etc.,were widely used in solar cells and light-emitting diodes.Although perovskite-type nanocrystals have relatively outstanding photoelectric properties,research in the field of photocatalysis is still in the experimental stage,mainly because although this material can be excited by visible light,its photocatalytic activity and materials Stability has been the main factor restricting its development.In this paper,Cs Pb Br₃nanocrystals were modified by noble metal doping and material compounding.Water-insoluble Sudan Red III with carcinogenic properties was selected as the target pollutant of the photocatalytic reaction.The visible light catalytic activity of the modified perovskite-type catalyst and the stability of its cyclic degradation were explored.The photocatalytic mechanism and the possible model of photocatalytic degradation.Low-cost Cs Pb Br₃nanocrystals were synthesized by recrystallization at room temperature,and graphene oxide?GO?was used to encapsulate the Cs Pb Br₃nanocrystals by in-situ synthesis.Then,the precious metal gold?Au?was reduced by surface ligand reduction.Doped in it to form Au-Cs Pb Br₃@GO composite photocatalyst.The SEM,EDS,XRD,PL,and laser particle size analysis were used to characterize the crystal structure,morphology,and optical properties of the modified photocatalyst.The characterization results show that the Au-Cs Pb Br₃@GO composite photocatalyst was successfully prepared.The addition of graphene oxide increases the specific surface area of the composite,provides a certain adsorption capacity and increases the number of reactive sites with organic pollutants,thereby increasing the photocatalytic activity;the doping of precious metal gold makes the surface and A built-in electric field is formed on the surface of Cs Pb Br₃to absorb photo-generated carriers,thereby reducing the recombination efficiency of photo-generated electron-hole pairs.Under the combined effect of these conditions,the catalytic activity of the composite photocatalyst is greatly improved.Photocatalytic degradation experiments show that 15mg of Au-Cs Pb Br₃@GO composite photocatalyst has the best photodegradation performance.It can degrade 60%of Sudan Red III at 60 minutes,and the degradation rate of Sudan Red III reaches 80%at 200 minutes.Free radical capture experiments show that in the Au-Cs Pb Br₃@GO-degraded Sudan Red III system,holes and hydroxyl radicals play a major role.And through the cycle degradation experiment,we know that the material has basically been inactivated in the second cycle experiment in the water system.After four cycles in the ethanol system,the degradation efficiency of Sudan Red III drops to about 10%,while in ethanol/toluene system,the degradation efficiency of Sudan III reduced to about 20%after four cycles of experiments.This shows that the polar stability of the Au-Cs Pb Br₃@GO composite photocatalyst is poor.Si O₂/Cs Pb Br₃composite photocatalyst was prepared by in-situ synthesis using TEOS as the precursor of silica.The SEM,EDS,XRD,PL,and laser particle size analysis were also used to characterize the crystal structure,morphology,and optical properties of the composite photocatalyst.The characterization results show that Si O₂/Cs Pb Br₃was successfully prepared with high purity.The characterization results show that the Cs Pb Br₃nanocrystals prepared by the ethanol/ultra-pure water system can remove excess Cs₄Pb Br₆impurities generated during the reaction to remove one Cs Br to generate Cs Pb Br₃,thereby improving the purity of the target product.The introduction of fine silica particles can effectively reduce the particle size of Cs Pb Br₃nanocrystals and increase their specific surface area,and make the Cs Pb Br₃nanocrystals effectively separated and not easily agglomerated,thereby increasing the photocatalytic performance of the composite photocatalyst;Si O₂/Cs Pb Br₃The increase in the photocatalytic activity of the composite is also due to the formation of active groups that can absorb holes on the surface of the silica,thereby effectively separating the electron-hole pairs.The degradation experiment of Sudan Red III showed that 10 mg,0.05 m L of TEOS-modified Si O₂/Cs Pb Br₃composite exhibited the most excellent photocatalytic activity,and could degrade nearly 55%of Sudan Red III in 200 min.Free radical masking experiments show that,as holes are captured by reactive groups,superoxide radicals play a leading role in the degradation of organics.The stability experiment shows that the stability of the lead-cesium halide perovskite modified with silica has been greatly improved,and the initial degradation efficiency is 55%.After four repeated experiments,the degradation efficiency is still 50%.Compared with Au-Cs Pb Br₃@GO composite photocatalyst,the stability has been reduced by about 10%,and the stability has been improved by nearly 7 times.Therefore,although the photocatalytic activity of the composite material modified with silica is not as good as the Au-Cs Pb Br₃@GO composite photocatalyst,it can also remove 55%of Sudan Red III while maintaining good stability.The purpose of this experimental study is to modify the lead-cesium halide perovskite photocatalyst by means of precious metal doping and surface compounding,so that it has more excellent visible light catalytic activity and stability,especially for polar solutions Greatly improved,while reducing the synthesis cost and improving the safety of the material preparation process,it provides a more certain theoretical basis for the future research of all-inorganic halogenated perovskite photocatalysts.