Photocatalytic Hydrogen Evolution from Water Using Fluorene and Dibenzothiophene Sulfone-Conjugated Microporous and Linear Polymers

Three series of conjugated microporous polymers (CMPs) were studied as photocatalysts for hydrogen production from water using a sacrificial hole scavenger. In all cases, dibenzo[b,d]thiophene sulfone polymers outperformed their fluorene analogues. A porous network, S-CMP3, showed the highest hydrogen evolution rates of 6076 mu mol h(-1) g(-1) (lambda > 295 nm) and 3106 mu mol h(-1) g(-1) (lambda > 420 nm), with an external quantum efficiency of 13.2% at 420 nm. S-CMP3 outperforms its linear structural analogue, P35, whereas in other cases, nonporous linear polymers are superior to equivalent porous networks. This suggests that microporosity might be beneficial for sacrificial photocatalytic hydrogen evolution, if suitable linkers are used that do not limit charge transport and the material can be wetted by water as studied here sorption and quasi-elastic neutron scattering.