Elucidating Metal Coordination Interactions in Pt‐Impregnated β‐Ketoenamine‐Imine Covalent Organic Frameworks for Efficient Photocatalytic Hydrogen Production

ABSTRACT Incorporating platinum (Pt) active species into metal‐free covalent organic frameworks (COFs) that possess exceptional structural regularity, robust stability, and a local coordination environment provides inspiration for designing high‐performance photocatalysts towards the hydrogen evolution reaction (HER). Nonetheless, rationally modulating metal coordination interactions in Pt‐decorated COF photocatalysts, a key factor governing the hydrogen‐evolving performance, is fundamentally challenging. Herein, we report a β ‐ketoenamine‐imine hybrid COF that achieves remarkably enhanced photocatalytic activity through an interfacial metal–coordination strategy. Compared with its conventional β ‐ketoenamine counterpart (PaTp‐3‐NT), the modified PaTp‐2‐NT nanohybrids deliver an exceptional hydrogen evolution rate of 17.2 mmol·g −1 ·h −1 at a low Pt loading. The adjacent ─C═N ─ and ─C═O chelating motifs in PaTp‐2‐NT constitute a bidentate coordination geometry that facilitates the precise anchoring of Pt species within the COF framework, yielding a specific Pt‐impregnated COF hybrid photocatalyst (PaTp‐2‐NT@Pt). The modulation of metal‐to‐ligand charge‐transfer (MLCT) pathways in the illuminated PaTp‐2‐NT@Pt is achieved by tailoring the local coordination environment from Pt (II) to N, O‐chelated Pt/COF complexes, thereby promoting extensive electron delocalization across the π‐conjugated framework via d‐π* orbital hybridization. Advanced experimental studies and density functional theory (DFT) calculations further verify the structural evolution, coordination microenvironment, and also the catalytic mechanism.