Coordination Environment in Single‐Atom Catalysts for High‐Performance Electrocatalytic CO₂ Reduction

The electrochemical reduction of carbon dioxide (EC CO 2 RR) is a promising technology to achieve a carbon‐neutral society. EC CO 2 RR can directly convert the greenhouse gas emitted from stacks into valuable fuels and chemical feedstocks for various industrial applications. Numerous metal‐based electrocatalysts have been researched to reduce overpotential and enhance the product selectivity of CO 2 RR. Recently, single‐atom catalysts (SACs) are attracting intensive attention due to their low‐cost, extremely high activities per loading amounts, and extensive stability of catalytic active sites due to the strong chemical interaction with coordination atoms. The coordination environments of SACs affect the electronic structure of active sites and change the energetics of the CO 2 RR pathways. Herein, the principles of EC CO 2 RR, including reaction mechanisms, figures of merits, and electrolysis systems, are first discussed. Then, the recent progress in the synthesis and characterization of SACs on various supports is accessed. Most importantly, the coordination environments of single‐metal atoms and their influence on CO 2 RR catalytic ability, product selectivity, and active site stabilization are focused. This review provides a milestone along the design of SACs from the perspective of optimizing atomic configuration surrounding the active sites for EC CO 2 RR.