In Situ Anchoring of Cu Single Atoms on CuS/ZnS with an Optimized d-Band Center for Efficient CO2 Photoreduction

Metal sulfides and their composite materials are broadly employed in photocatalytic CO₂ reduction and water splitting, arising from their outstanding photochemical properties. However, the strong CO adsorption capacity of metal sulfides greatly inhibits the CO production performance. Herein, to weaken the Cu–C bond, Cu/CuS/ZnS composites were developed via a straightforward in situ thermal post-treatment method. It was found that the optimized Cu/CuS/ZnS composite demonstrated superior photocatalytic CO₂ conversion to CO activity at 58.7 μmol g^–1 h^–1, approximately 3.3 times higher than CuS/ZnS. According to experimental and density functional theory (DFT) calculation results, Cu single atoms (SAs) not only reduce the reduction energy barrier but also effectively downshift the d-band center of Cu. Consequently, the adsorption capacity of CO will be reduced, thus greatly improving the photocatalytic CO production activity. This study offers valuable insights into the creation of stable atomic-scale composite catalysts.