Delocalized Frustrated Lewis Pairs in COF‐Catalyzed N‐Transfer for Urea Photosynthesis

Abstract

Abstract Photosynthesis of urea through C─N coupling from CO 2 and nitrates (NO 3 − ) represents a sustainable route for both carbon utilization and environmental remediation, yet remains fundamentally challenging due to competing parallel reduction reactions. Building upon hard‐soft acid‐base principles, we demonstrate that electronic delocalization modulation in iron (Fe)‐keto oxygen frustrated Lewis pairs (FLPs) can effectively suppress these reductions while selectively promoting C─N coupling. To realize this strategy, we engineered a fluorinated Fe‐β‐ketoenamine‐linked covalent organic framework (Fe/F─COF) photocatalyst, where F functionalization modulates the electronic structure to create electron‐delocalized FLPs with precisely controlled Fe‐keto oxygen spatial spacing at 3.4 Å. Experimental and computational results reveal that F‐induced electron delocalization enhances Lewis acidity at Fe sites for NO 3 − activation and increases basicity at keto oxygen for the CO 2 activation. Furthermore, the electron‐delocalized Fe center exhibits softened acid character that weakens the Fe‐N bond in adsorbed *NH species, facilitating N‐transfer for C─N coupling. Such spatial and electronic configuration lowers the C─N coupling barrier, favoring *NHCO intermediate formation and subsequent urea production. The Fe/F‐COF achieves a high urea yield rate of 93 µmol g cat. −1 h −1 with an apparent quantum yield of 1.1% at 400 nm, surpassing most reported photocatalytic co‐reduction coupling systems to date.