Engineering structural defects into a covalent organic framework for enhanced photocatalytic activity

Defect engineering is a promising methodology for modulating the electronic and band structure of semiconductive materials. A series of covalent organic frameworks, designated TAPT-COF-X (X = mole equivalents of modulator 3,5-dimethylbenzaldehyde relative to three equivalents of linker) for water-splitting have been prepared bearing a controlled proportion of structural defects. These defects significantly enhanced photocatalytic H-2 production. Hydrogen evolution rates of 33 910 mu mol g(-1) h(-1) were achieved, with the maximum H-2 evolution rate for TAPT-COF-7 2.3 times that of parent TAPT-COF. Time-resolved fluorescence measurements and electrochemical impedance spectroscopy indicated that TAPT-COF-7 also possessed the highest charge separation efficiency.