A covalent organic framework constructed from a donor–acceptor–donor motif monomer for photocatalytic hydrogen evolution from water

Abstract

Covalent organic frameworks (COFs), featuring semiconductor-like behavior, have recently garnered widespread interest for applications in photocatalysis by virtue of their well-defined and tailorable porous structures, high surface areas and excellent chemical stability. A facile strategy for designing COFs exerting efficient charge transfer and separation as well as suppressing charge carrier recombination is the precise integration of electron-donating and electron-withdrawing moieties to form long-range ordered donor–acceptor (D–A) type structures. In this work, we rationally designed and synthesized a novel imine-linked COF (DABT-Py-COF) by the condensation of a newly designed D–A–D type monomer of 4,4′,4′′,4′′′-(benzo[c][1,2,5]thiadiazole-4,7-diylbis(9,9-dimethyl-9,10-dihydroacridine-10,2,7-triyl))tetrabenzaldehyde and 1,3,6,8-tetrakis(4-aminophenyl)pyrene under solvothermal conditions. Remarkably, the obtained DABT-Py-COF exhibited outstanding and steady hydrogen production with a maximum hydrogen evolution rate (HER) of 5458 μmol g⁻¹ h⁻¹ under visible-light irradiation (AM 1.5). This work has paved the way for the rational design and preparation of more efficient D–A type COFs for photocatalysis.