S-scheme heterojunctions can preserve strong redox capacity on the basis of achieving spatial separation of photogenerated carriers.Therefore,a deep comprehension of the photoinduced charge transfer dynamics in S-sche...S-scheme heterojunctions can preserve strong redox capacity on the basis of achieving spatial separation of photogenerated carriers.Therefore,a deep comprehension of the photoinduced charge transfer dynamics in S-scheme heterostructures is vital to enhancing photocatalytic properties.Herein,SnO_(2)/BiOBr S-scheme heterojunctions with tight contact are fabricated with in situ hydrothermal method.The optimal SnO_(2)/BiOBr exhibits excellent photocatalytic performance for CO_(2)reduction,with yields of CO and CH4 of 345.7 and 6.7μmol∙g^(–1)∙h^(–1),which are 5.6 and 3.7 times higher than those of the original BiOBr.The photoinduced charge transfer mechanism and dynamics of SnO_(2)/BiOBr S-scheme heterostructure are characterized by in situ X-ray photoelectron spectrum(XPS)and femtosecond transient absorption spectroscopy(fs-TA).A new fitted lifetime of photogenerated carriers are observed,which could be attributed to interfacial electron transfer of S-scheme heterojunction,further illustrating an ultrafast transfer channel for photoelectrons from SnO_(2)conduction band to BiOBr valence band.As a result,the powerful reduced electrons in BiOBr conduction band and the powerful oxidation holes in SnO_(2)valence band are retained.This work provides profound comprehension of photoinduced charge transfer mechanism of S-scheme heterojunction.展开更多
Reforming CO_(2)into storable solar fuels via semiconductor photocatalysis is considered an effective strategy to solve the greenhouse effect and resource shortage.Unfortunately,the problem of rapid photogenerated car...Reforming CO_(2)into storable solar fuels via semiconductor photocatalysis is considered an effective strategy to solve the greenhouse effect and resource shortage.Unfortunately,the problem of rapid photogenerated carriers severely limits the CO_(2)reduction capability of one-component catalysts.The fabrication of S-scheme heterojunctions with defects can result in efficient spatial separation of photo-generated charge carriers and increase adsorption and activation of nonpolar molecules.Herein,ZnWO_(4)/g-C_(3)N_(4)S-scheme heterojunctions with defects are constructed through in situ growth method.The experiments show that the generation rate of CO from CO_(2)reduction is up to 232.4μmol∙g^(−1)∙h^(−1)with a selectivity close to 100%,which is 11.6 and 8.5 times higher than those of pristine ZnWO_(4)and g-C_(3)N_(4),respectively.In situ XPS and work function analyses demonstrate the S-scheme charge transport pathway,which facilitates the spatial segregation of photogenerated carriers and promotes CO_(2)reduction.In situ ESR illustrates that CO_(2)molecules are adsorbed by nitrogen vacancies,which act as photoelectron acceptors during the photocatalytic reaction and are favorable for charge trapping and separation.The S-scheme charge transport mode and nitrogen vacancy work together to stimulate the efficient conversion of CO_(2)to CO.This work presents significant insights to the cooperative influence of the S-scheme charge transport mode and defects in regulating CO_(2)reduction activity.展开更多
文摘S-scheme heterojunctions can preserve strong redox capacity on the basis of achieving spatial separation of photogenerated carriers.Therefore,a deep comprehension of the photoinduced charge transfer dynamics in S-scheme heterostructures is vital to enhancing photocatalytic properties.Herein,SnO_(2)/BiOBr S-scheme heterojunctions with tight contact are fabricated with in situ hydrothermal method.The optimal SnO_(2)/BiOBr exhibits excellent photocatalytic performance for CO_(2)reduction,with yields of CO and CH4 of 345.7 and 6.7μmol∙g^(–1)∙h^(–1),which are 5.6 and 3.7 times higher than those of the original BiOBr.The photoinduced charge transfer mechanism and dynamics of SnO_(2)/BiOBr S-scheme heterostructure are characterized by in situ X-ray photoelectron spectrum(XPS)and femtosecond transient absorption spectroscopy(fs-TA).A new fitted lifetime of photogenerated carriers are observed,which could be attributed to interfacial electron transfer of S-scheme heterojunction,further illustrating an ultrafast transfer channel for photoelectrons from SnO_(2)conduction band to BiOBr valence band.As a result,the powerful reduced electrons in BiOBr conduction band and the powerful oxidation holes in SnO_(2)valence band are retained.This work provides profound comprehension of photoinduced charge transfer mechanism of S-scheme heterojunction.
文摘Reforming CO_(2)into storable solar fuels via semiconductor photocatalysis is considered an effective strategy to solve the greenhouse effect and resource shortage.Unfortunately,the problem of rapid photogenerated carriers severely limits the CO_(2)reduction capability of one-component catalysts.The fabrication of S-scheme heterojunctions with defects can result in efficient spatial separation of photo-generated charge carriers and increase adsorption and activation of nonpolar molecules.Herein,ZnWO_(4)/g-C_(3)N_(4)S-scheme heterojunctions with defects are constructed through in situ growth method.The experiments show that the generation rate of CO from CO_(2)reduction is up to 232.4μmol∙g^(−1)∙h^(−1)with a selectivity close to 100%,which is 11.6 and 8.5 times higher than those of pristine ZnWO_(4)and g-C_(3)N_(4),respectively.In situ XPS and work function analyses demonstrate the S-scheme charge transport pathway,which facilitates the spatial segregation of photogenerated carriers and promotes CO_(2)reduction.In situ ESR illustrates that CO_(2)molecules are adsorbed by nitrogen vacancies,which act as photoelectron acceptors during the photocatalytic reaction and are favorable for charge trapping and separation.The S-scheme charge transport mode and nitrogen vacancy work together to stimulate the efficient conversion of CO_(2)to CO.This work presents significant insights to the cooperative influence of the S-scheme charge transport mode and defects in regulating CO_(2)reduction activity.
