Molecular engineering of donor–acceptor sp2-carbon-linked covalent organic frameworks for enhancing photocatalytic hydrogen production

Three sp 2 -carbon-linked D–A COFs have been successfully synthesized via a Knoevenagel condensation reaction. The TTh-COF with strong electron-donating unit of benzotrithiophene exhibits an impressive hydrogen evolution rate 22.22 mmol h −1 g −1 .