Boron-Doped Nickel-Nitrogen-Carbon Single-Atom Catalyst for Boosting Electrochemical CO₂ Reduction

Tuning the coordination environment of the metal center in metal-nitrogen-carbon (M-N-C) single-atom catalysts via heteroatom-doping (oxygen, phosphorus, sulfur, etc.) is effective for promoting electrocatalytic CO2 reduction reaction (CO2RR). However, few studies are investigated establishing efficient CO2 reduction by introducing boron (B) atoms to regulate the M-N-C structure. Herein, a B-C3N4 self-sacrifice strategy is developed to synthesize B, N co-coordinated Ni single atom catalyst (Ni-BNC). X-ray absorption spectroscopy and high-angle annular dark field scanning transmission electron microscopy confirm the structure (Ni-N3B/C). The Ni-BNC catalyst presents a maximum CO Faradaic efficiency (FECO) of 98.8% and a large CO current density (j(CO)) of -62.9 mA cm(-2) at -0.75 and -1.05 V versus reversible hydrogen electrode, respectively. Furthermore, FECO could be maintained above 95% in a wide range of potential windows from -0.65 to -1.05 V. In situ experiments and density functional theory calculations demonstrate the Ni-BNC catalyst with B atoms coordinated to the central Ni atoms could significantly reduce the energy barrier for the conversion of *CO2 to *COOH, leading to excellent CO2RR performance.