Preparation And Catalytic Performance Of Cesium Lead Bromide And Its Water-Resistant Composites

Environmental pollution,especially water pollution,is becoming more and more serious.The semiconductor photocatalytic technology that came into being has great significance for environmental protection and sustainable development of society.However,due to the low photocatalytic efficiency,the development of new and efficient photocatalysts has become the key to the widespread application of photocatalytic technology.At present,all-inorganic lead halide perovskites have become promising materials for photoelectric applications due to their good photoelectric conversion performance.However,due to its ionic structure being very unstable in water,there have been no reports on the photocatalytic application of all inorganic lead halide perovskites in water systems.In this paper,try to apply cesium lead bromide(CsPbBr₃)to photocatalytic degradation of tetracycline hydrochloride(TC-HCl)in organic systems to evaluate the photocatalytic activity of materials firstly.Then,the surface of CsPbBr₃ was modified with silica(SiO₂),and the CsPbBr₃@SiO₂core-shell structure composite was prepared,and it was successfully applied to the photocatalytic degradation of TC-HCl in water system.Finally,CsPbBr₃ was compounded with titanium dioxide(TiO₂)microspheres with excellent charge transport properties,which greatly improved its photocatalytic activity and stability in water system.Details are as follows:(1)In this experiment,all-inorganic perovskite cesium lead bromide quantum dots(CsPbBr₃ QDs)were successfully prepared by the antisolvent method.The study found that the prepared CsPbBr₃ is unstable in water,and is easily transformed into the perovskite-like phase Cs Pb₂Br₅,which leads the loss of photocatalytic activity.CsPbBr₃ QDs were applied to visible light photocatalytic degradation under ethanol system,and TC-HCl was used as a model reactant to evaluate its photocatalytic activity.76%TC-HCl was degraded in 30 minutes,which shows that CsPbBr₃ quantum dots can be used as effective photocatalysts in ethanol.The photocatalytic degradation process was analyzed by high performance liquid chromatography(HPLC).It was found that CsPbBr₃ quantum dots could degrade TC-HCl selectively in ethanol system.The photoelectric conversion efficiency and photoluminescence quantum yield of the catalyst were measured and calculated.It was found that superoxide radicals(·O₂^-)played a major role in photocatalytic degradation through capture experiments,and a reaction mechanism was proposed.This work shows that CsPbBr₃ can be used as an effective photocatalyst to remove pollutants in organic systems,which will be beneficial to the development of new photocatalysts and applications in special fields.(2)In this experiment,the CsPbBr₃@SiO₂ core-shell composite was prepared by a simple precipitation coating method,and its photocatalytic activity was evaluated by degrading TC-HCl in water under visible light as a model reaction.The results show that CsPbBr₃@SiO₂ composites exhibit enhanced photocatalytic activity.In order to further study the reasons for the increase in photocatalytic activity,we first studied the photoelectric conversion properties of CsPbBr₃@SiO₂ composites by electrochemical methods and photoluminescence.The results show that the addition of SiO₂ reduces the impedance and lowers the energy barrier of the interface reaction,thereby promoting the transfer of photogenerated electrons,increasing the photogenerated current of the composite product,and reducing the photogenerated electron-hole recombination.The active materials in the photocatalytic process were explored through capture experiments.The results show that holes(h⁺)and superoxide radicals(·O₂^-)are the main sources of photocatalytic active materials.This experiment is the first application of cesium lead bromide composites to photocatalytic degradation of pollutants in water.This research provides new ideas for expanding the application of all-inorganic lead halide perovskites and developing efficient photocatalysts.(3)In this experiment,CsPbBr₃ nanoparticles were prepared by a solvothermal method,and added it to the titanium precursor for encapsulation,then CsPbBr₃-TiO₂composites were synthesized by 200°C solvothermal and 400°C calcination.Photocatalytic degradation performance was tested by degrading TC-HCl in water under visible light as a model reaction.The results show that TiO₂ microspheres can effectively protect CsPbBr₃ nanoparticles and significantly improve the photocatalytic performance of CsPbBr₃-TiO₂ composites.The more CsPbBr₃ nanoparticles per unit area in the material,the better the adsorption effect of the sample on TC-HCl.Photoelectrochemical and photoluminescence performance tests were used to study the photoelectric conversion characteristics of the composites,the results show that the addition of TiO₂ reduces the charge transfer resistance at the interface of the composites,which is beneficial to increase the electron-hole separation rate and thus improve the photocatalytic activity.The active materials in the photocatalytic process were explored through capture experiments.The results show that holes(h⁺)and superoxide radicals(·O₂^-)are the main active materials in photocatalytic reactions.This experiment provided new possibilities for further research and application of water-resistant perovskite composites and new photocatalytic composites.