Tuning the Microenvironment of Co−N₄ Ensemble for Co Single‐Atom Catalysts for Electrocatalytic CO₂ Reduction

Single‐atom catalysts (SACs), with their well‐defined structure, serve as an efficient catalyst model for studying the structure‐performance relation in the electrocatalytic CO 2 reduction reaction (CO 2 RR). Current CO 2 RR research primarily focus on the coordination interactions between metal single atoms and coordinated ligands, while the impact of the metal SAC′s microenvironment remains largely unexplored. Herein, we generate three microenvironments for a CoN 4 ensemble by using different nitrogen sources to prepare Co SACs, i. e. pyridine‐type Co−N 4 (Co−N 4 SAC Phen ), the pyrrole‐type Co−N 4 (Co−N 4 SAC Dp ) and the mixed‐type Co−N 4 (Co−N 4 SAC Mm ). It reveals that the Co−N 4 SAC Phen contributes to CO generation with 99.5 % selectivity at −0.76 vs RHE, whereas the Co−N 4 SAC Dp accelerates a severe hydrogen evolution reaction. Experimental studies confirmed that the Co−N 4 SAC Phen possesses distinctive electrochemical properties and electronic structure, with the pyridine‐N being more conducive to electron accumulation and exhibited a higher electron delocalization, thereby promoting the generation of CO. This study deepens our understanding of the cobalt SAC′s microenvironment‘s influence on CO 2 RR.