Chalcogen heteroatoms doped nickel-nitrogen-carbon single-atom catalysts with asymmetric coordination for efficient electrochemical CO2 reduction

The electronic configuration of central metal atoms in single-atom catalysts (SACs) is pivotal in electrochemical CO2 reduction reaction (eCO(2)RR). Herein, chalcogen heteroatoms (e.g., S, Se, and Te) were incorporated into the symmetric nickel-nitrogen-carbon (Ni-N-4-C) configuration to obtain Ni-X-N-3-C (X: S, Se, and Te) SACs with asymmetric coordination presented for central Ni atoms. Among these obtained Ni-X-N-3-C (X: S, Se, and Te) SACs, Ni-Se-N-3-C exhibited superior eCO(2)RR activity, with CO selectivity reaching similar to 98% at -0.70 V versus reversible hydrogen electrode (RHE). The Zn-CO2 battery integrated with Ni-Se-N-3-C as cathode and Zn foil as anode achieved a peak power density of 1.82 mW cm(-2) and maintained remarkable rechargeable stability over 20 h. In-situ spectral investigations and theoretical calculations demonstrated that the chalcogen heteroatoms doped into the Ni-N-4-C configuration would break coordination symmetry and trigger charge redistribution, and then regulate the intermediate behaviors and thermodynamic reaction pathways for eCO(2)RR. Especially, for Ni-Se-N-3-C, the introduced Se atoms could significantly raise the d-band center of central Ni atoms and thus remarkably lower the energy barrier for the rate-determining step of *COOH formation, contributing to the promising eCO(2)RR performance for high selectivity CO production by competing with hydrogen evolution reaction. (c) 2024, Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. All rights reserved.