Low‐Coordinated Ni Single Atom Catalyst with Carbon Coordination for Efficient CO2 Electroreduction

A low-coordinated Ni single atom catalyst (SAC) is synthesized by nitrogen elimination method, characterized by an undersaturated coordination structure with carbon coordination. This configuration induces moderate electron depletion at its Ni sites, which enhances the adsorption of *COOH while concurrently facilitating the subsequent desorption of *CO, thereby contributing to the greatly improved electrocatalytic performance of carbon dioxide reduction.

Abstract

In essence, electrocatalytic CO₂ reduction reaction (CO₂RR) process for the CO₂-to-CO conversion involves two critical reactive intermediates: *COOH and *CO. The trade-off between the adsorption of *COOH and the desorption of *CO is challenging for Ni-based CO₂RR catalysts. The high-valence Ni site is inadequate in supplying sufficient electrons for CO₂ activation and subsequent adsorption of *COOH; conversely, the metallic Ni site with abundant electron exhibits excessively strong π-backbonding with *CO, thus hindering its desorption. Here, the study reports a low-coordinated Ni single atom catalyst (SAC) characterized by a low-coordinated structure with carbon coordination, thereby engineering a moderate electron depletion at its Ni sites. This Ni SAC achieves a high selectivity for CO production up to 99.1% in H-cell. Additionally, it maintains an ultrahigh CO selectivity near 100% across a broad range of current densities in flow cell, coupled with sustained stability at a large current of 250 mA cm⁻² for 20 h. Both in situ characterization results and density functional theory (DFT) calculations confirm the dual functionality of this low-coordinated structure, as it enhances the adsorption of *COOH while concurrently facilitating the subsequent desorption of *CO, thus greatly promoting the overall CO₂RR process.