A heptazine-based polymer photocatalyst with donor-acceptor configuration to promote exciton dissociation and charge separation

Polymeric carbon nitride (PCN) is an emerging class of polymer semiconductor photocatalysts, but bulk PCN typically suffers from low visible-light-harvesting ability, high activation energy, and rapid charge recombination. In this context, using the same core building block, a donor-acceptor (D-A) type heptazine-based polymer, namely BPCN, was proposed via Friedel-Crafts arylation reaction to tackle these issues. Comparatively, the affording BPCN features extended light absorption, reduced activation energy, and suppressed charge recombination, triggered by the electron push-pull interactions as a consequence of the D-A configuration. BPCN is elucidated to be an effective heterogeneous photocatalyst for aerobic organic transformations and a wide range of substrate scopes and reactions were realized. Besides, BPCN also showed an advantage in mediating the photocatalytic water oxidation reaction, achieving a nearly 10-fold oxygen evolution reaction (OER) rate over PCN. These findings demonstrate the great potential of the rational design of heptazine-based polymers with D-A configurations for artificial photosynthesis.