Preparation And Photocatalytic CO₂ Reduction Performance Of MAPbBr₃ Based Heterojunction

In recent years,in order to solve the greenhouse effect and environmental problem caused by the massive use of fossil fuels,the use of green and mild photocatalytic technology to reduce the concentration of CO₂ in the atmosphere has become the focus of scientists.Photocatalytic reduction of CO₂ can convert atmospheric CO₂ into energy materials,so various semiconductors have been developed for the application of photocatalytic reduction of CO₂.Among them,halide perovskite is a promising photocatalytic material with suitable band gap and strong absorption capacity of visible light.However,the photogenic carrierh of halide perovskite is tend to compound and the stability of it is poor,which greatly limits its industrial application.In this paper,three strategies are proposed to improve the photocatalytic CO₂reduction performance of halide perovskite by improving the photoelectron-hole pair separation rate and significantly optimizes stability of MAPb Br₃ in water vapor.The main contents are as follows:（1）The heterojunction catalyst MAPb Br₃/La₂Ti₂O₇ prepared by high energy ball milling was prepared by using MABr and Pb Br₂ as precursors,which combined with MAPb Br₃ and La₂Ti₂O₇.The formation of heterojunction can realize the effective separation of photogenerated carriers,thus improving the performance of MAPb Br₃ photocatalytic reduction of CO₂.The characteristic diffraction peaks of MAPb Br₃ and La₂Ti₂O₇ indicate the successful preparation and combination of the two.SEM analysis showed that MAPb Br₃ and La₂Ti₂O₇were successfully recombined.The results show that the successful recombination of MAPb Br₃/La₂Ti₂O₇ improves the photocatalytic CO₂ reduction performance of the composite catalyst.（2）In this experiment,the self-assembly of core-shell structure was realized by solvothermal method.The MAPb Br₃ was used as a self-sacrificing template.Control the dissociation of MAPb Br₃ at appropriate temperature to make the Pb-MOF grew in-situ and evenly wrapped MAPb Br₃,which significantly increases the stability of MAPb Br₃ in water vapor.The formation of heterojunction effectively realizes the separation of photogenerated carriers.Meanwhile,the water resistance stability of the composite catalyst is also improved to a certain extent due to the coating of Pb-MOF on the outside of perovskite.（3）In this experiment,the MABr and Pb Br₂ mixed in certain proportions.Under the action of mechanical ball milling,MAPb Br₃ showed irregular blocky form,which combined with Bi Fe O₃ nanosheets to form heterojunction.Based on the heterojunction,the piezoelectric material Bi Fe O₃ generates a polarized electric field as the driving force of photogenerated carrier separation by introducing mechanical force through ultrasound.The photogenerated carrier separation can be realized under the dual-energy driving system of illumination and piezoelectricity.XRD and TEM analyses show that Bi Fe O₃ and MAPb Br₃ are successfully prepared and recombined,and XPS maps prove that there is an effective charge transfer between them.The photoluminescence（PL）spectra and the time-resolved photoluminescence（TRPL）spectra further demonstrate rapid charge transfer in heterojunction.The experimental results showed that in the dual-drive system,the composite catalytic MAPb Br₃/Bi Fe O₃ showed stronger photocatalytic CO₂ reduction performance,and the product selectivity was also improved.