硫空位提升2D/2D In2.77S4/CuInS2 S型异质结光催化还原CO2为C2H4选择性OA

Converting CO2 into multi-carbon hydrocarbons through artificial photosynthesis remains challenging due to sluggish C-C coupling dynamics and complex multi-electron processes.In this study,ultrathin In2.77S4/CuInS2 heterojunctions with abundant sulfur vacancies(SV)were synthesized via a one-step hydrothermal method.The S-scheme charge-transfer mechanism,driven by the built-in electric field,was confirmed through in situ X-ray photoelectron spectroscopy(XPS),femtosecond transient absorption spectroscopy(fs-TAS)and photoelectrochemical characterization.This S-scheme heterojunction not only enhanced the separation efficiency of photogenerated charge carriers but also maintained excellent reduction capability,enabling CO2 photoreduction to C2 hydrocarbons.Furthermore,experimental results and density functional theory(DFT)calculations demonstrated that SV shortened the Cu-In active site distance,optimized the local charge density and lowered the energy barrier for critical dimer formation(*CHOCO),thereby accelerating the C-C coupling kinetics.Finally,the In2.77S4/CuInS2-4 catalyst exhibited excellent yield(47.2 μmol g-1 h-1)and selectivity(99.1%)of C2H4,which attributed to the synergistic effect of efficient carrier rectification by the S scheme heterojunction and optimized C-C coupling dynamics facilitated by SV.Furthermore,isotope labeling confirmed CO2 as the sole carbon source for the reaction.Overall,this"sulfur vacancy-heterojunction"strategy for CO2 photoreduction to C2H4 with superior electron selectivity offers valuable insights into CO2 utilization.