In the pursuit of efficient photocatalytic carbon dioxide(CO_(2))conversion,the use of artificial semiconductors powered by solar energy offers great potential for simulating natural carbon cycling.However,the efficie...In the pursuit of efficient photocatalytic carbon dioxide(CO_(2))conversion,the use of artificial semiconductors powered by solar energy offers great potential for simulating natural carbon cycling.However,the efficiency of photocatalytic CO_(2)conversion remains suboptimal,primarily due to inadequate separation of photogenerated charges,which hinders the performance of semiconductor-based CO_(2)reduction.Consequently,recent research efforts have focused on identifying ideal materials for CO_(2)photocatalytic conversion.Among the candidate materials,the structure of Bi_(2)MoO_(6)consists of alternating layers of(Bi_(2)O_(2))2+and perovskite-like(MoO4)2-layers with shared oxygen atoms between them.This inherent charge distribution within Bi_(2)MoO_(6)creates an inhomogeneous electric field,facilitating the efficient separation of photogenerated charge carriers.The morphology and structure of a catalyst significantly influence the rate of recombination of photogenerated charge carriers.Research has shown that ultrathin Bi_(2)MoO_(6)nanosheets,compared to other 2D and 3D structures of Bi_(2)MoO_(6)materials,possess longer fluorescence lifetimes,providing more opportunities for the separation of photogenerated charge carriers.However,Bi_(2)MoO_(6)still exhibits relatively low catalytic efficiency due to its insufficiently negative conduction band position(ranging between-0.2 and-0.4 V).To address this limitation,a viable strategy is to load a semiconductor with a more negatively positioned conduction band onto Bi_(2)MoO_(6),creating an S-scheme heterojunction.In this study,Bi_(2)MoO_(6)nanosheets were synthesized through a hydrothermal method,and simultaneously,CeO_(2)nanoparticles were grown on their surfaces,forming an S-scheme heterojunction modified with Ce^(3+)/Ce^(4+)ion bridges.Time-resolved photoluminescence(TRPL)and photoelectrochemical tests demonstrated the enhanced charge separation effect of this heterojunction.In situ X-ray photoelectron spectroscopy(In situ XPS)analysis and theoretical calculations further confirmed that photogenerated electrons follow an S-scheme mechanism,transferring from Bi_(2)MoO_(6)to CeO_(2).Experimental results revealed that the photocatalytic CO_(2)reduction efficiencies of CeO_(2)/Bi_(2)MoO_(6),Bi_(2)MoO_(6),and CeO_(2)were 65.3,14.8,and 1.2μmol·g^(-1)·h^(-1),respectively.Compared to pure Bi_(2)MoO_(6),the catalytic efficiency of the CeO_(2)/Bi_(2)MoO_(6)composite catalyst for CO_(2)photocatalytic reduction to CO improved by a factor of 3.12.This enhancement in photocatalytic CO_(2)conversion performance can be attributed to the synergistic interaction between the S-scheme heterojunction and Ce^(3+)/Ce^(4+)ion bridging,resulting in enhanced light absorption,efficient charge separation,and redox capabilities of the composite catalyst.This study offers valuable insights into the rational design and construction of novel S-scheme heterojunction photocatalysts.展开更多
文摘In the pursuit of efficient photocatalytic carbon dioxide(CO_(2))conversion,the use of artificial semiconductors powered by solar energy offers great potential for simulating natural carbon cycling.However,the efficiency of photocatalytic CO_(2)conversion remains suboptimal,primarily due to inadequate separation of photogenerated charges,which hinders the performance of semiconductor-based CO_(2)reduction.Consequently,recent research efforts have focused on identifying ideal materials for CO_(2)photocatalytic conversion.Among the candidate materials,the structure of Bi_(2)MoO_(6)consists of alternating layers of(Bi_(2)O_(2))2+and perovskite-like(MoO4)2-layers with shared oxygen atoms between them.This inherent charge distribution within Bi_(2)MoO_(6)creates an inhomogeneous electric field,facilitating the efficient separation of photogenerated charge carriers.The morphology and structure of a catalyst significantly influence the rate of recombination of photogenerated charge carriers.Research has shown that ultrathin Bi_(2)MoO_(6)nanosheets,compared to other 2D and 3D structures of Bi_(2)MoO_(6)materials,possess longer fluorescence lifetimes,providing more opportunities for the separation of photogenerated charge carriers.However,Bi_(2)MoO_(6)still exhibits relatively low catalytic efficiency due to its insufficiently negative conduction band position(ranging between-0.2 and-0.4 V).To address this limitation,a viable strategy is to load a semiconductor with a more negatively positioned conduction band onto Bi_(2)MoO_(6),creating an S-scheme heterojunction.In this study,Bi_(2)MoO_(6)nanosheets were synthesized through a hydrothermal method,and simultaneously,CeO_(2)nanoparticles were grown on their surfaces,forming an S-scheme heterojunction modified with Ce^(3+)/Ce^(4+)ion bridges.Time-resolved photoluminescence(TRPL)and photoelectrochemical tests demonstrated the enhanced charge separation effect of this heterojunction.In situ X-ray photoelectron spectroscopy(In situ XPS)analysis and theoretical calculations further confirmed that photogenerated electrons follow an S-scheme mechanism,transferring from Bi_(2)MoO_(6)to CeO_(2).Experimental results revealed that the photocatalytic CO_(2)reduction efficiencies of CeO_(2)/Bi_(2)MoO_(6),Bi_(2)MoO_(6),and CeO_(2)were 65.3,14.8,and 1.2μmol·g^(-1)·h^(-1),respectively.Compared to pure Bi_(2)MoO_(6),the catalytic efficiency of the CeO_(2)/Bi_(2)MoO_(6)composite catalyst for CO_(2)photocatalytic reduction to CO improved by a factor of 3.12.This enhancement in photocatalytic CO_(2)conversion performance can be attributed to the synergistic interaction between the S-scheme heterojunction and Ce^(3+)/Ce^(4+)ion bridging,resulting in enhanced light absorption,efficient charge separation,and redox capabilities of the composite catalyst.This study offers valuable insights into the rational design and construction of novel S-scheme heterojunction photocatalysts.
