Controllable Fabrication of Atomic Dispersed Low-Coordination Nickel-Nitrogen Sites for Highly Efficient Electrocatalytic Co2 Reduction

Single-atom catalysis has been considered as a powerful approach for CO 2 reduction reaction (CO 2 RR) to achieve efficient resource conversion and carbon neutrality. The electrocatalytic activity of single-atom catalysts (SACs) is closely related to the local coordination environment. Herein, Ni SACs with well-defined low-coordination nickel-nitrogen sites (denoted as Ni SA @N 3 -C) have been successfully developed via a facile sacrificial template method. XAS results reveal that the coordination environment of the atomically dispersed Ni active sites can be controlled by the pyrolysis temperature. Significantly, the Ni SA @N 3 -C displays remarkably excellent activity toward electrocatalytic CO 2 RR with CO Faradaic efficiency (FE CO ) of 96.0% at -0.83 V vs . RHE and remains high FE CO exceeding 90% over a broad potential range from -0.63 to -0.93 V vs . RHE, outperforming those of Ni SA @N 4 -C and Ni NP @NC. Density functional theory (DFT) calculations further suggest that the Ni single atoms coordinated by three N atoms possesses a suitable free energy barrier for *COOH formation and *CO desorption, thereby exhibiting the most excellent CO 2 RR performance. This study sheds a new light on the design of SACs with controllable coordination structures for CO 2 RR