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 (CO2RR), 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 CO2RR. 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 CO2RR 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 CO2RR.•FECO 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.