Topology Regulation of Donor-Acceptor Conjugated Polymers for Solar-Driven Hydrogen Production

Conjugated polymers, especially those with a donor-acceptor (D-A) structure, are emerging as potent photocatalysts for solar-to-chemical energy conversion. However, even constructed with identical D-A building blocks, conjugated polymers with diverse topologies can yield distinct photocatalytic properties, underscoring the significance of topology regulation. Herein, two conjugated polymers, Bi-CBTP with a D-A₂ motif and Tri-CBTP with a D-A₃ motif, were designed with identical building blocks, and synthesized via a low-energy, rapid sonochemical method to investigate the influence of topologies on photocatalytic hydrogen production. Comprehensive theoretical calculations and femtosecond transient absorption (fs-TA) spectroscopy reveal that the topology profoundly regulates the planarity, exciton binding energy, and electron push-pull effect of the D-A conjugated polymer. Specifically, Bi-CBTP achieves a rather high hydrogen production rate of 516.7 mmol g^-1 h^-1 as the state-of-art performance under simulated solar irradiation, along with a 61.2% apparent quantum efficiency (AQE) at 420 nm. This work provides valuable insights into the design of high-performance polymer photocatalysts for solar hydrogen production.