Regulating the coordination metal center in immobilized molecular complexes as single-atomic electrocatalysts for highly active, selective and durable electrochemical CO2 reduction.

For electrochemical carbon dioxide reduction (CO 2 RR), metal–N sites exhibit promising catalytic activity, yet the structure–activity relationship remains largely unclear. Here we synthesize well-defined homogeneous catalysts containing four coordinating pyridine N atoms, regulate the coordination metal centers in immobilized molecular complexes, and investigate their catalytic performances in CO 2 RR. The resulting Co(qpy)/CNTs composite exhibit the highest efficiency. Its Faradaic efficiency for CO reaches >98% over the broad range from −0.5 V to −0.9 V (vs. RHE), with long-term stability over 100 h. Density functional theory calculations reveal that the larger electronic overlap between the catalytic site and intermediate can decrease the free energy change for *COOH formation. The calculation results are experimentally verified by changing the metal centers (Fe(qpy), Ni(qpy) and Cu(qpy)). This work unveils the relationship between metal–ligand coordination and CO 2 RR performance, and offers a strategy for the design and synthesis of high-performance catalysts for practical applications. [Display omitted] • Various metal centers with four coordinating pyridine N are regulated for CO 2 RR. • FE CO of Co(qpy)/CNTs reaches above 98% from −0.5 to −0.9 V over 100 h. • DFT reveal that the larger electronic overlap can decrease free energy for *COOH. [ABSTRACT FROM AUTHOR]