Nickel Nanocluster‐Stabilized Unsaturated Ni‐N3 Atomic Sites for Efficient CO2‐to‐CO Electrolysis at Industrial‐Level Current

Unsaturated Ni single atom catalysts (SACs), Ni‐Nx (x=1,2,3), have been investigated to break the conventional Ni‐N4 structural limitation and provide more unoccupied 3d orbitals for CO2RR intermediates adsorption, but their intrinsically low structural stability has seriously hindered their applications. Here, we developed a strategy by integrating Ni nanoclusters to stabilize unsaturated Ni‐N3 atomic sites for efficient CO2 electroreduction to CO at industrial‐level current. DFT calculations revealed that the incorporation of Ni nanocluster effectively stabilizes the unsaturated Ni‐N3 atomic sites and modulates their electronic structure to enhance the adsorption of the key intermediate *COOH during CO2RR. Guided by these insights, we prepared an optimal composite catalyst, Ni6@Ni‐N3, which features a Ni6N6 nanocluster surrounded by six Ni‐N3 single atoms sites, through low‐temperature pyrolysis. As a result, Ni6@Ni‐N3 demonstrated a remarkably high CO Faradaic efficiency (FECO) of 99.7% and a turnover frequency (TOF) of 83984.2 h‐1 at 500 mA cm‐2 under ‐1.15 VRHE, much better than the conventional Ni‐N4 . XAS analyses of Ni6@Ni‐N3 before and after long‐term CO2RR testing confirmed the excellent stability of its coordinative environment. This work highlights a generalizable approach for stabilizing unsaturated single‐atom catalysts, paving the way for their application in high‐performance CO2RR.