Defective three-dimensional covalent organic frameworks for enhanced hydrogen peroxide photosynthesis and organic transformation

Covalent organic frameworks with three-dimensional networks and interconnected porous structures show promising advantages for hydrogen peroxide photocatalysis. However, 3D COFs are typically constructed from 3D-oriented knots with less conjugation and insufficient light absorption, which significantly inhibits their performance. Herein, we present a universal defect engineering approach by systematically replacing T_d knots with trigonal planar ligands and modifying linear linkers with electron-withdrawing/donating groups to achieve simultaneous enhancement of light absorption and precise electronic tuning of 3D donor-acceptor structures. Experimental results and theoretical analysis reveal that the optimized 3D COF with planar ligands induced defects and fluorine functional groups (COF-300-D-F), which achieve an H₂O₂ production rate of 19.09 mmol g^-1 h^-1 and apparent quantum yield of 11.95% at 400 nm with benzyl alcohol as sacrificial agent. Moreover, the material maintains long-term stability during continuous operation exceeding 96 hours and exhibits high activity in photocatalytic benzylamine coupling reactions.