Engineered atomically dispersed cobalt sites in one-dimensional pyridine-based covalent organic frameworks for enhanced photocatalytic CO2 reduction

Abstract

Metal-coordinated covalent organic frameworks (COFs) have attracted significant attention for photocatalytic CO₂ reduction, but the precise role of coordination microenvironment engineering and the topological structure in modulating charge transfer dynamics remains unclear. Herein, we synthesized two novel one-dimensional COF architectures incorporating distinct chelating motifs – phenanthroline and imine–pyridine units. By anchoring cobalt ions, two atomically dispersed cobalt-coordinated COFs (Co-Phen-COF and Co–Py-COF) were successfully constructed for efficient photocatalytic CO₂ reduction. Notably, the Co–Py-COF exhibited superior photoelectric properties and a higher CO generation rate compared to the pristine COF and Co-Phen-COF. Experimental and theoretical analyses revealed that the synergistic interaction between single-atom Co²⁺ sites and the one-dimensional Py-COF configuration enhanced CO₂ adsorption, promoted charge migration and carrier separation, and lowered the formation energy barrier of the rate-determining intermediate. Mechanistic studies demonstrated that the localized charges at the interface of Co sites and the Py-COF were redistributed and more photogenerated electrons were accumulated around the single-atom Co²⁺ sites in the Co–Py-COF, promoting CO₂ activation and improving CO₂ reduction efficiency. This study offers a promising strategy for optimizing photocatalytic CO₂-to-CO conversion by fine-tuning metal-chelating microenvironments within COFs.