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 CO 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.