Structural isomerization of novel donor–donor–acceptor conjugated microporous polymers by regulating the linking positions of pyrene for efficient photocatalytic hydrogen production

Conjugated microporous polymers (CMPs) have attracted considerable interest in photocatalytic water splitting due to their remarkable photocatalytic efficiency. However, their practical application is hindered by low charge separation efficiency and severe charge recombination, making the rational design of novel CMP architectures crucial for overcoming these limitations. Building upon the donor–acceptor (D–A) framework, this study presents a novel donor–donor–acceptor (D–D–A) structural motif, wherein pyrene units (Py) arising from the use of two distinct pyrene-derived units serves as dual donor and dibenzo[b,d]thiophene-S,S-dioxide (BTDO) acts as the acceptor. By employing substitutional isomeric Py monomers and utilizing a ternary statistical copolymerization strategy, three structurally distinct D–D–A type CMPs P-1,6-P-BTDO, P-2,7-P-BTDO, and P-1,8-P-BTDO were successfully synthesized. Comprehensive structural design, coupled with photoelectrochemical characterization and photocatalytic hydrogen evolution test, it has been demonstrated that P-1,6-P-BTDO constructed from 1,6-dibromopyrene exhibits a high hydrogen evolution rate of 26.5mmol g^-1h⁻¹ under visible light illumination (λ > 420 nm, no noble metal cocatalyst), which is 3.2 times higher than that of the conventional D–A type counterpart P-BTDO (8.22mmol g^-1h⁻¹) and ranks among the best for noble-metal-free CMPs using ascorbic acid as the sacrificial agent. The apparent quantum yield (AQY) of P-1,6-P-BTDO reaches 7.6% at 420 nm, and the catalyst maintains over 95% of its initial activity after six consecutive cycles (12 h), demonstrating excellent stability. In comparison with conventional D–A type CMPs, the incorporation of the dual donor architecture facilitates the generation of photogenerated electrons and significantly improves the separation efficiency of electron-hole pairs in CMPs photocatalysts, thereby boosting photocatalytic activity. This work not only validates the efficacy of the D–D–A molecular design in enhancing the performance of CMP-based photocatalysts, but also offers a new avenue for fine-tuning material properties through precise control of monomer substitution patterns.