A 1,3,5-triazine and benzodithiophene based donor-acceptor type semiconducting conjugated polymer for photocatalytic overall water splitting

Donor–acceptor domains hold the key to tailoring photochemical properties and charge carrier mobility of conjugated microporous polymers (CMPs) for application in photocatalytic water splitting. Herein, a family of electron-withdrawing 1,3,5-triazine and electron-donating fused thiophene based porous polymers are obtained via C–H arylation. The TBT-BDT showed an excellent HER of 4238 ​μmol ​g−1 ​h−1, which is 17-fold and 3-fold higher than that of TBT-Th and TBT-TT, respectively. In addition, TBT-BDT facilitates overall water splitting to produce stoichiometric amounts of H2 (28 ​μmol ​g−1 ​h−1) and O2 (14 ​μmol ​g−1 ​h−1). The significant difference in the photocatalytic performance was mainly ascribed to the band structure change of the polymers, which underlined the importance of the donor unit on the performance of D−A type photocatalysts and indicated that thiophene-contained unit BDT is an excellent donor for high photocatalytic activity. A family of electron-withdrawing 1,3,5-triazine and electron-donating fused-thiophene based conjugated microporous polymers (CMPs) are obtained via C–H arylation. As a result, the band structure as well as the photocatalytic performance of CMPs was tuned by rationally adjusting electron-rich monomers and TBT-BDT achieved photocatalytic overall water splitting in pure water. [Display omitted] •A novel thiophene-based CMP(TBT-BDT) was synthesized.•The D-A type CMPs showed broad light absorption and narrow band gap.•The band structure of CMPs was tuned by adjusting electron-rich monomers.•The platinum/nickel-loaded TBT-BDT achieves overall water splitting.