Highly dispersed Co-modified covalent organic frameworks as bridging cocatalysts for boosting CO2 photoreduction over defective carbon nitride

Abstract

It is still a great challenge to increase both the active sites and charge separation of earth-abundant catalysts for efficient and durable photocatalytic CO₂ conversion. To achieve these aims, we designed imine-linked covalent organic frameworks as the electron bridge that links the photocatalyst and robust metal active sites for photocatalytic CO₂ reduction. When integrated with defective g-C₃N₄, the composite generated 37.3 μmol h⁻¹ of CO with 98.8% selectivity over H₂ evolution under visible light irradiation, which greatly outperformed other non-noble metal species as cocatalysts. Experimental and theoretical results demonstrated that the stabilized Co ions with a six-membered chelating structure effectively improved the collection of excited electrons and stability of the catalyst. This study provides a new protocol to improve CO₂ photoreduction performance through coupling defect-modulated photocatalysts with bridging cocatalysts.