Modulating Electron Density of Ni-N-C Sites by N-doped Ni for Industrial-level CO2 Electroreduction in Acidic Media

Graphical We find that the N-doped Ni particles can enhance the adsorption of CO 2 and modulate the configuration of adsorbed CO on Ni-N-C sites. As a result, the optimal catalyst can efficiently convert CO 2 into CO with a faradaic efficiency of 96.7 % and a current density of 500 mA cm −2 in a strongly acidic electrolyte. Electro-chemically reducing CO 2 in a highly acidic medium is promising for addressing the issue of carbonate accumulation. However, the hydrogen evolution reaction (HER) typically dominates the acidic CO 2 reduction. Herein, we construct an efficient electro-catalyst for CO formation based on a core-shell structure, where nitrogen-doped Ni nanoparticles coexist with nitrogen-coordinated Ni single atoms. The optimal catalyst demonstrates a significantly improved CO faradaic efficiency (FE) of 96.7 % in the acidic electrolyte (pH=1) at an industrial-scale current density of 500 mA cm −2 . Notably, the optimal catalyst maintains a high FE of CO exceeding 90 % (current density=500 mA cm −2 ) in the electrolyte with a wide pH range from 0.67 to 14. In-situ spectroscopic characterization and density functional theory calculations show that the local electron density of Ni-N-C sites is enhanced by N-doped Ni particles, which facilitates the formation of *COOH intermediate and the adsorption of *CO. This study demonstrates the potential of a hybrid metal/Ni-N-C interface in boosting acidic CO 2 electro-reduction.