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

Abstract

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 (CO₂ RR). However, few studies are investigated establishing efficient CO₂ reduction by introducing boron (B) atoms to regulate the M-N-C structure. Herein, a B-C₃ N₄ 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-N₃ B/C). The Ni-BNC catalyst presents a maximum CO Faradaic efficiency (FE_CO ) 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, FE_CO 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 CO₂ RR performance.

Keywords: CO2 reduction; coordination environment; heteroatom doping; nickel single atoms.