Research progress in photocatalytic reduction of CO2 to CH4
Exploring the mechanism of photocatalytic CO2 reduction reaction is of great significance for im-proving photocatalytic reduction efficiency and product selectivity.In this review,the basic principles and widely accepted pathways of photocatalytic CO2 reduction to C1 products(formaldehyde pathway and car-bene pathway)were first summarized.Secondly,methods to improve CO2 photoreduction efficiency and CH4 selectivity were summarized,as well as semiconductor modification methods such as constructing het-erojunctions,designing structural defects,introducing single atom catalysts,and other methods.The spe-cific analysis is as follows:(1)combining two suitable electronic band structure semiconductors to form a heterojunction can improve the separation efficiency of photogenerated carriers,thus increasing the number of photogenerated charges to promote the multi proton multi electron coupling reaction,and improve the probability of photocatalytic CO2 to generate CH4;(2)design structural defects can expand the spectral absorption range,adjust the bandgap position,and promote the excitation and separation of photogenerat-ed charges,while the density and properties of vacancies can be adjusted by changing the synthesis condi-tions;(3)the introduction of single atom catalysts can improve the active site of the catalyst,and adjust the adsorption/desorption strength of reactants,intermediates,and products;(4)other methods:surface regulation and doping.By modifying semiconductors,the photocatalytic efficiency and selectivity for CO2 reduction of CH4 are greatly improved,providing effective means for the rational utilization of CO2.The article concludes by point-ing out the challenges and development prospects faced by CO2 photoreduction of CH4.
photocatalysisCO2CH4heterojunctiondefect engineeringsingle atom catalyst
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