Preparation And Photocatalytic CO₂ Reduction Performance Of BiOCl_xBr_1-x/ACSs Catalyst

In recent years,the increasing CO₂ level in atmosphere has caused a series of environmental challenges,such as the greenhouse effect.The photocatalysis technology presents potential applications for resource conversion of CO₂.The heart of this technology is the construction of the photocatalyst.Theoretical calculations and experimental results demonstrate that the BiOCl_xBr_1-x-x photocatalysts possess the unique layered-structure and indirect transition mode of BiOX?X=Cl,Br?,and their energy band structures are controlled by changing the ratio of X,realizing good catalytic activities.These catalysts were prepared according to the difference in the solubility of BiOX.The mesoporous structures result in the weak adsorption capacity of CO₂ and the powder is easily agglomerated,which limit the photocatalytic activities of BiOCl_xBr_1-x.In the present work,we prepared the solid solution BiOCl_xBr_1-x at room temperature using a simple method.Afterwards,the activated carbon spheres?ACSs?with strong adsorption capacity for CO₂ were used as the carrier,obtaining BiOCl_xBr_1-x/ACSs composite by impregnation method.The research content and results are as follows:?1?We dispersed BiOBr powders prepared by the hydrolysis method into different concentration HCl aqueous solutions to synthesize a series of BiOCl_xBr_1-x catalysts.XRD,EDX,SEM,BET and DRS were used to characterize e its composition,morphology,specific surface area,pore structure,light absorption and photoelectric properties.The Bi OCl_xBr_1-x photocatalyst and a amount of CO₂ were placed in a photocatalytic reduction CO₂ evaluation system.Under simulated sunlight irradiation,the photocatalytic CO₂ reduction performance was investigated.The experimental results show that H⁺and Cl^-in HCl solution change the structure and composition of BiOBr,affecting its energy band structure and morphology,which influence its photocatalytic CO₂reduction performance.The CO yield increased first and then decreased with increasing of HCl concentration.Results indicate that there is particular emphasis placed on the roles of H⁺and Cl^-ions in the micro-and macro-performance improvements of BiOBr photocatalysts.Our findings should provide important knowledge for further understanding the roles of H⁺and Cl^-ions in such‘like-BiOX'layered-structure systems.?2?In order to improve the adsorption capacity of CO₂ and solve the problem of aggregation of the powder catalyst,we used suspension polymerization method to prepare phenolic resin spheres,which were activated by water vapor during the high-temperature carbonization process.Then BiOCl_xBr_1-x/ACSs photocatalyst was prepared by impregnation method.It was found that BiOCl_xBr_1-x of BiOCl_xBr_1-x/ACSs system maintains the original morphology of the nanosheets,while the light absorption performance of change significantly and the performance has been greatly improved.The photocatalytic CO₂ reduction performance of BiOCl_xBr_1-x and BiOCl_xBr_1-x/ACSs was investigated under simulated sunlight irradiation.The yield of CO in the BiOCl_xBr_1-x/ACSs system was found to be higher than that of the powder BiOCl_xBr_1-x.