Photocatalytic Hydrogen Evolution from Water Using Heterocyclic Conjugated Microporous Polymers: Porous or Non-Porous?

Three series of conjugated microporous polymers (CMPs) were studied as photocatalysts for producing hydrogen from water using a sacrificial hole-scavenger. In all cases, dibenzo[b,d]thiophene sulfone polymers outperformed their fluorene analogs. A porous network, S-CMP3, showed the highest hydrogen evolution rate of 6076 µmol h^-1 g^-1 (λ > 295 nm) and 3106 µmol h^-1 g^-1 (λ > 420 nm), with an external quantum efficiency of 13.2% at 420 nm. S-CMP3 outperforms its linear structural analog, P35, while in other cases, non-porous linear polymers are superior to equivalent porous networks. This suggests that microporosity can be beneficial for sacrificial photocatalytic hydrogen evolution, but not for all monomer combinations.