Flexible, nonfused sulfone functionalized polymer with enhanced active site access for photocatalytic sacrificial hydrogen evolution.

The fused sulfone unit has been a key building block for hydrogen evolution photocatalysts for 9 years but still faces the challenge of a poor water/polymer interface due to its rigid structure. This work introduces nonfused, flexible sulfur segments (SSs) into the polymer's backbone to enhance hydrophilicity and active site access. Unlike rigid, fused sulfone moieties, our flexible SS improves interfacial water contact and charge transport. P-2SO, with sulfone-functionalized SS, represents a 237% improvement over the control polymer, PBDTTSO. In addition, P-2SO demonstrated an outstanding hydrogen evolution rate of 1060.1 micromoles per hour and an apparent quantum yield of 32.4% (460 nanometers). Molecular dynamics simulations indicate SS improves hydrophilicity and water/polymer interface while promoting a hairpin-like conformation that increases intrachain π-π stacking for better charge hopping. Transient absorption spectroscopy shows sulfone-functionalized SS enhances electron transfer to platinum cocatalysts, increases active site density, and reduces exciton migration lengths through stronger polymer/platinum interactions.