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

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 mu mol h(-1) of CO with 98.8% selectivity over H-2 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.

Automated summary

This research presents a new approach to enhance the efficiency and durability of photocatalytic CO2 conversion by designing imine-linked covalent organic frameworks as an electron bridge between the photocatalyst and robust metal active sites. The composite, integrated with defective g-C3N4, achieved a high CO production rate of 37.3 μmol/h with 98.8% selectivity over H2 evolution under visible light irradiation, surpassing other non-noble metal species as cocatalysts. Experimental and theoretical analysis revealed that stabilized Co ions with a six-membered chelating structure effectively improved electron collection and catalyst stability. The study demonstrates the potential of coupling defect-modulated photocatalysts with bridging cocatalysts to enhance CO2 photoreduction performance.