Pyrene-alt-dibenzothiophene-S,S-dioxide copolymers for highly efficient photocatalytic hydrogen production: The role of linking pattern

Two analogous positional polymers P16PySO and P27PySO have been synthesized via the copolymerization from dibenzothiophene-S,S-dioxide and pyrene building blocks. The effect of the linking pattern on the molecular packing, photophysical and photocatalytic properties of the two isomers was investigated. It was interestingly found that a minor change at the substitution position of pyrene unit was demonstrated to largely influence the photocatalytic properties of the two isomers. P16PySO exhibited an encouraging average hydrogen evolution rate (HER) of 619.5 μmol h −1 and the maximum HER of 774 μmol h −1 , much higher than that of 2,7-counterpart with a moderate rate of 282 μmol h −1 . The increased photocatalytic activity of P16PySO is mainly ascribed to its more ordered molecular packing, broader absorption region, better wettability , and higher photo-generated charge mobilities. Moreover, the optimum HER was increased from 774 to 1013 μmol h −1 when the amount of the photocatalyst P16PySO was increased from 50 to 100 mg, which is among the top solar-to‑hydrogen conversion efficiencies reported so far for the polymeric photocatalysts.