Cu doping induced asymmetric Cu-Vs-In active sites in In₂S₃ for efficient photocatalytic C₂H₄ conversion from CO₂

Selective reduction of CO₂ to value-added C₂-chemical fuels, (such as C₂H₄) holds great promise for directly converting solar energy into chemical energy. However, the weak adsorption of CO₂ on photocatalysts directly affects its conversion efficiency. Here we use Cu doping to create asymmetric Cu-S-vacancies-In (Cu-V_S-In) sites in the two-dimensional In₂S₃, which greatly improves CO₂ adsorption, achieving efficient photocatalytic reduction of CO₂ to C₂H₄. Experiments and DFT (Density functional theory) calculations show that Cu doping, due to the influence of charge balance, will induce S vacancies and change the coordination environment around In atoms. This changes the mode of CO₂ adsorption and decreases the adsorption energy of CO₂. The asymmetric Cu-V_S-In sites promote charge transfer to the C[sbnd]O bond, increasing catalytic activity. The concept of using asymmetric sulfur vacancies to simultaneously regulate both adsorption and charge transfer between catalysts and reactants provides a design guide for the development of advanced catalytic materials aimed at photocatalytic CO₂ reduction.