Regulating the N-coordination environment of single-atom active sites in covalent organic frameworks for boosting photocatalytic CO2 reduction

Abstract

The catalytic properties of single-atom catalysts with N atoms coordinated metal sites are highly dependent on their coordination environment, but a clear and systematic study of CO₂ reduction performances affected by the type of coordinated N atoms is still lacking. Herein, by using Co single-atom incorporated covalent organic frameworks (COF) catalyst as a well-defined platform, we demonstrate that changing one coordinated N atom from pyrazine N to pyridine N can successfully improve the activity and selectivity of photocatalytic CO₂ reduction in the presence of triethanolamine as sacrificial agent. Both the experimental and theoretical results reveal that regulating the type of coordinated N atoms can modulate the electronic structure of single-atom Co sites in COF, resulting in enhanced CO₂ adsorption ability, improved electron trapping capability and reduced formation energy barriers of *COOH intermediate for facilitating CO₂ reduction and simultaneously suppressing H₂ evolution. This work sheds light on the significance of coordination atoms regulation in single-atom catalysts for improving catalytic performances.