Solvothermal Synthesis Of Lead Halogen Perovskite And Its Electrochemical And Photocatalytic Properties

Organic-inorganic hybrid perovskite materials are widely concerned by researchers due to their structural designability,gas sensitivity and excellent photoelectric chemical properties.In order to meet the needs of modern society for multifunctional materials,this topic selects lead-halide perovskite MAPbX₃?X=Br,I?materials as research objects,and uses reactive groups to modify the materials,providing a theoretical basis for its application in the field of energy storage electrode materials and photocatalytic degradation.The MAPbI₃ and MAPbBr₃ crystal materials were prepared by solvothermal method,and the effects of reaction temperature and time on the crystal morphology were investigated.The growth mechanism,phase structure,optical properties and carrier properties of the crystals were investigated by SEM,XRD,UV-Vis,HALL,PL and other test methods.The experimental results showed that the two crystals obtained under the optimal preparation parameters have uniform morphology,fewer defects and excellent carrier performance,and the diffusion lengths were 2.07?m and 2.08?m,respectively.The time evolution experiments showed that the growth mechanism of the two crystals was the Ostwald ripening mechanism and the aggregation and assembly growth mechanism.The excessive reaction time would destroy the crystal structure.MAPbI₃ was induced and modified by low concentration ammonia?NH₃?atmosphere,and the materials were characterized by SEM,HALL,XRD and FTIR and other analytical methods.The test results showed that the appropriate atmosphere treatment time increases the conductivity and reactive area of the material.Compared with MAPbI₃,the improved specific capacities and cycling performance(132 mAh·g^-1 at300th cycle)of sample treated by 30 min NH₃ gas could be ascribed to the kinetically faster lithium ion diffusion rate(5.26×10^-9 cm²·s^-1)and the nanorod-like cluster structure with small volume effect,and the reaction mechanism of weak coordination complex formed during molecular dynamic exchange was proposed.MAPbBr₃/p-C₃N₄ composite materials were successfully prepared by adding protonated carbon nitride?p-C₃N₄?.The effects of adding carbon nitride on the phase structure,optical properties and carrier performance of MAPbBr₃ were investigated by XRD,SEM,FTIR,TRPL and other test methods.The results showed that the interfacial charge transfer behavior of p-C₃N₄ makes it easier to extract the electrons in MAPbBr₃,and improves the ratio of active photogenic electrons.The interfacial charge transfer rate was k_et=2.83×10⁹ s^-1,and the hole transfer behavior of p-C₃N₄ would be used as a propellant to accelerate the reaction,the hole transfer rate was k_ht=4.90×10⁶ s^-1.In addition,the degradation rate of organic dye malachite green?MG?with p-C₃N₄ doping of 1 mg could reach 98.7%when exposed to visible light for 20 min,4.5 times higher than that of original MAPbBr₃.Moreover,the recycling times of p-C₃N₄ were more than10 times,which significantly improved the catalytic activity and stability.The experimental results of free radical detection showed that the improvement of performance is due to the activation process of molecular oxygen.