S型CeO2/Bi2MoO6微球异质结的理性设计及其高效光催化CO2还原OA北大核心CSTPCD

In the pursuit of efficient photocatalytic carbon dioxide(CO2)conversion,the use of artificial semiconductors powered by solar energy offers great potential for simulating natural carbon cycling.However,the efficiency of photocatalytic CO2 conversion remains suboptimal,primarily due to inadequate separation of photogenerated charges,which hinders the performance of semiconductor-based CO2 reduction.Consequently,recent research efforts have focused on identifying ideal materials for CO2 photocatalytic conversion.Among the candidate materials,the structure of Bi2MoO6 consists of alternating layers of(Bi2O2)2+and perovskite-like(MoO4)2-layers with shared oxygen atoms between them.This inherent charge distribution within Bi2MoO6 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 Bi2MoO6 nanosheets,compared to other 2D and 3D structures of Bi2MoO6 materials,possess longer fluorescence lifetimes,providing more opportunities for the separation of photogenerated charge carriers.However,Bi2MoO6 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 Bi2MoO6,creating an S-scheme heterojunction.In this study,Bi2MoO6 nanosheets were synthesized through a hydrothermal method,and simultaneously,CeO2 nanoparticles were grown on their surfaces,forming an S-scheme heterojunction modified with Ce3+/Ce4+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 Bi2MoO6 to CeO2.Experimental results revealed that the photocatalytic CO2 reduction efficiencies of CeO2/Bi2MoO6,Bi2MoO6,and CeO2 were 65.3,14.8,and 1.2 µmol·g-1·h-1,respectively.Compared to pure Bi2MoO6,the catalytic efficiency of the CeO2/Bi2MoO6 composite catalyst for CO2 photocatalytic reduction to CO improved by a factor of 3.12.This enhancement in photocatalytic CO2 conversion performance can be attributed to the synergistic interaction between the S-scheme heterojunction and Ce3+/Ce4+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.