The defect engineering and S-bridged d-p-p orbital hybridization synergistically enhance CO₂ electroreduction

Ni-based catalysts are promising candidates for electrocatalytic reduction of CO₂ to CO, but their intrinsic electronic structure is still a key obstacle to achieving high catalytic performance. Heteroatom doping and defect engineering are effective strategies for regulating the band structure of catalysts. Herein, sulfur-bridged nickel/carbon catalysts containing structural defects (Ni-S1@CVC) are innovatively designed. DFT results show that the incorporation of S atoms successfully form the d-p-p hybrid orbitals and shift Ni 3d orbital energy toward the Fermi level. Additionally, carbon defect induced by electron-rich ligand regulated electron distribution around the S atom, successfully activating the Ni-S-C directional electron transport channels. Thereby continuous internal electrons induced by sulfur bridging and carbon vacancy are rapidly transferred to the reaction site and injected into the surface *CO₂, promoting the rapid formation and stability of *COOH. The Faradaic efficiency of CO reaches 98% in Ni-S1@CVC. Compared with Ni@CVC, the partial current density for CO is enhanced by 34 times at -0.98 V vs. RHE in Ni-S1@CVC. This work has new insights on the electron transport of sulfur-bridged transition metal/carbon composite catalysts and provides new ideas for the design of catalysts.