Donor-Acceptor Cyanocarbazole-Based Supramolecular Photocatalysts for Visible-Light-Driven H2 Production.

Highly efficient, stable, and metal-free supramolecular photocatalysts for H2 production are uncommon and of significant interest. In this study, a donor-acceptor (D-A) cyanocarbazole-based supramolecule (2CzPN) is assembled by intermolecular C≡N⋅⋅⋅H-Ar H-bonding interactions to form an efficient, stable, and metal-free photocatalyst for H2 evolution. The catalyst affords an H2 production rate of 91.8 μmol h-1 (20 mg of samples, λ>420 nm) and a corresponding apparent quantum efficiency of 7.5 % at 420 nm. The photon-generated carrier separation of the 2CzPN supramolecule, which is higher than that of the analogous polymer, can be attributed to the strong D-A characteristics and high crystallinity. This study offers the first experimental evidence of visible-light H2 evolution among D-A cyanocarbazole-based supramolecules and it enriches the variety of supramolecular photocatalysts. This stable and effective metal-free 2CzPN supramolecular photocatalyst has obvious advantages among very few supramolecular photocatalysts for H2 production.