Hydroxyl‐Bridged Phosphorus Doping‐Induced Charge Polarization Enhancing Electron Delocalization for Efficient Photoreduction of CO 2

ABSTRACT 2D metal‐free carbon nitride (CN) with extensive π–π conjugated structures suffers from electron localization due to p z orbital overlap, which severely limits its photocatalytic CO 2 reduction performance. Herein, we propose an electron delocalization strategy via functional group‐modified heteroatom doping. Through DFT screening and three‐step copolymerization of phytic acid and urea, we precisely synthesized a 4‐coordinated OH‐bridged P‐doped carbon nitride (CN−POH) featuring a unique 2N–P═OOH microstructure within heptazine units. CN−POH achieves a CO production rate of 1.82 mmol g −1 h −1 , 15 times higher than pristine CN. Experimental and theoretical results reveal that P doping disrupts the π–π conjugation, triggering electron delocalization and transferring electrons to adjacent active N sites. The OH‐modified P atom forms 2N–P═OOH coordination, inducing spatial charge polarization between VBM and CBM, which significantly enhances charge separation and electron delocalization. This unique structure also converts CO 2 adsorption from physical to chemical mode under the effect of water solvents and facilitates CO 2 ‐to‐CO conversion via hydrogen bonding with the water solvent. Collectively, CN−POH emerges as a highly efficient photocatalyst for CO 2 reduction. This work provides a promising strategy for electron delocalization in CN materials and introduces a new reaction mechanism incorporating solvent molecule interactions.