Construction of Modifiable Phthalocyanine-Based Covalent Organic Frameworks with Irreversible Linking for Efficient Photocatalytic CO2 Reduction

Abstract Covalent organic frameworks (COFs) are considered promising catalysts for photocatalytic CO 2 reduction reaction (pCO 2 RR) due to facilitated regulations. However, the instability of COFs with dynamic reversible covalent bonds and the limited modifiability of COFs with irreversible covalent bonds restricted the enhancement of the pCO 2 RR performance. Herein, three phthalocyanine-based COFs with ether-linked, CoOP, CoPOP, and CoBOP, were successfully prepared via in situ polycondensation using modifiable bis-phthalonitrile. CoBOP achieved a record of syngas performance in pCO 2 RR systems with photosensitizers and sacrificial agents (CO 83.7 mmol g −1 h −1 and H 2 54.7 mmol g −1 h −1 ), surpassing most COF photocatalysts. Additionally, CoOP, CoPOP, and CoBOP exhibit stabilities in extreme environments owing to their irreversible covalent bonds. Experimental and density functional theory analyses confirm that the optimally matched the lowest unoccupied molecular orbital of the linking unit between the photosensitizer and active unit endowed CoBOP with the highest photoelectron transfer efficiency among the three catalysts, boosting its pCO 2 RR activity. This work is highly instructive for designing COFs with structure-adjustable and irreversible covalent bonds.