Construction Of Bismuth Oxychloride-based Materials For Co₂ Reduction And Their Enhanced Photocatalytic Performance

During the period of rapid development of society and science and technology,a large amount of energy is consumed rapidly,causing energy crisis,environmental pollution and ecological damage,which need to be solved urgently.Semiconductor photocatalysis technology uses light energy to drive the reduction of CO₂ into carbon-based fuels,which is expected to solve the environmental and energy problems faced by mankind.In recent years,BiOCl photocatalytic materials with a unique layered structure have received extensive attention due to their better photocatalytic activity.However,the BiOCl material has shortcomings such as the light absorption range is limited to the ultraviolet region and the separation efficiency of photogenerated carriers is low.In this paper,the modification of BiOCl material was studied.Through morphology control,bismuth-rich strategy,heterojunction structure and surface defect construction,the visible light absorption capacity and photo-generated carrier separation efficiency are effectively improved.The photocatalytic CO₂ reduction performance is effectively improved.In addition,the composition,structure,photoelectric properties and possible photocatalytic mechanism of the prepared bismuth oxychloride-based materials were studied.The specific content is as follows:1.The porous BiOCl ultrathin nanosheets were prepared by ball milling method.Transmission electron microscopy results confirmed that the prepared BiOCl ultra-thin nanosheets have obvious porous structures on the surface.The structure of porous structure exposes more（001）crystal faces,forming（110）/（001）crystal face heterojunction,which improves the efficiency of photo-generated carrier migration and separation.The pore structure of BiOCl ultra-thin nanosheets enhances the CO₂adsorption performance,thereby improving its photocatalytic CO₂ reduction performance.The photocatalytic CO₂ reduction process was further analysis by in-situ FT-IR,it is found that COOH*is the main reaction intermediate,and proposed a possible photocatalytic mechanism.2.Under normal temperature and pressure,CPDs/Bi₁₂O₁₇Cl₂ composite materials were prepared by uniformly loading different contents carbonized polymer dots（CPDs）on the surface of ultra-thin Bi₁₂O₁₇Cl₂ nanosheets by simple mechanical stirring.The structure,morphology and photoelectric properties of the prepared materials were analyzed.The oxygen production performance test showed that the photogenerated carriers of the CPDs/Bi₁₂O₁₇C1₂ composite materials migrated in a Z-scheme mechanism.The improved photocatalytic CO₂ reduction performance of CPDs/Bi₁₂O₁₇Cl₂ is attributed to the enhanced visible light absorption capacity,photo-generated carrier migration and separation efficiency and exposure more active sites.A possible photocatalytic mechanism is proposed.3.Two-dimensional PbBiO₂Cl（PBOC）atomic layer material were constructed by solvothermal method,then calcined in H₂/Ar mixed atmosphere to prepare PBOC atomic layer materials with different surface oxygen vacancy concentrations.A series of characterization and theoretical calculations results show that the construction of atomic layer structure of oxygen-rich defects（ROVs）is conducive to the migration and separation of photogenerated electrons,and OVs can be used as the adsorption and activation sites of CO₂ molecules and the intermediate product COOH*,so as to improve the photocatalytic CO₂ reduction performance of the material.Under Xe lamp irradiation,the ROV PBOC-1 shows the largest CO yield(16.02μmol g^-1 h^-1),which is 2.7 and 18.0 times of PBOC and bulk PBOC,respectively.A possible photocatalytic mechanism is proposed through in-situ FT-IR and theoretical calculations.