Preparation Of Bi₄O₅Br₂/MOFs Composite Catalyst For Photocatalytic Reduction Of CO₂

Due to the increasing demand for fossil fuels in modern society,the greenhouse effect of carbon dioxide（CO₂）as one of the combustion products is an environmental problem that we urgently need to solve.Using effective catalysts to reduce CO₂ to organic products through artificial photosynthesis can not only alleviate energy shortages but also solve environmental problems,so it is particularly important to explore available photocatalysts.Metal organic frameworks（MOFs）,as one of the promising photocatalysts,have a wide band gap which limits their further application in the field of photocatalysis.The post-synthesis modification of MOFs and the construction of heterojunctions with other semiconductors are enhanced an effective solution for photocatalytic performance.In this paper,two new types of Bi₄O₅Br₂/MOFs-based composite photocatalysts were designed and constructed,which were used to catalyze the reduction of carbon dioxide to carbon monoxide and methane in an isopropanol system through light.The specific research content is as follows:（1）Study on photocatalytic reduction of CO₂ by X%NPC-Mo S₂/Bi₄O₅Br₂ composite materials under ultraviolet lightThe precursor Mo-MOF of Mo S₂ was prepared by heating in an oil bath,and a rod-shaped Mo S₂ containing nitrogen doped carbon was obtained by using a CVD growth system and a N₂ purge method,which was named NPC-Mo S₂.Using the Bi₄O₅Br₂ ultra-thin two-dimensional nanosheet structure and abundant active sites,by constructing and preparing different ratios of X%NPC-Mo S₂/Bi₄O₅Br₂heterojunctions,the reduction CO₂ activity under ultraviolet light was studied.When the content of NPC-Mo S₂ is 5%wt,the best photocatalytic performance was shown.（2）Study on photocatalytic reduction of CO₂ by X%Bi₄O₅Br₂/Fe-MIL composite materials under simulated sunlightThe precursor of Bi₄O₅Br₂ material was prepared by solvothermal method.After hydrolysis,a hollow spherical bismuth-rich material was obtained,which was used as a solid acid to adjust two visible light-responsive Fe-MOF(NH₂-MIL-101（Fe）to NH₂-MIL-88B（Fe）of the transformation of the crystal morphology.By adjusting the amount of Bi₄O₅Br₂ added to form a heterojunction with NH₂-MIL-88B（Fe）,the electron transport was accelerated,the electron-hole recombination rate was reduced,and it exhibited excellent photocatalytic reduction of CO₂ to produce methane under simulated sunlight.,greatly improving the photocatalytic reduction of CO₂ activity.