Triptycene incorporated carbon nitride based donor-acceptor conjugated polymers with superior visible-light photocatalytic activities.

Polymeric carbon nitride (CN) has evoked considerable attention in photocatalysis, however, its π-deficiency conjugated frameworks engendering weak visible-light absorption and rapid charge recombination hinder the practical utilizations. Herein, a novel donor-acceptor (D-A) conjugated polymer based on triptycene incorporated carbon nitride (T-CN) has been facilely prepared by thermal copolymerization of melamine and 2,6,14-triaminotriptycene. Combined with the density functional theory (DFT) calculations, it is found that the formation of intramolecular charge transfer and the extended π-conjugative effect in the D-A structure contribute to a broadened light-harvesting spectral range, a higher charge separation/transfer efficiency and more active sites of T-CN for photoredox reactions. The T-CN catalyst accomplished superior visible-light photocatalytic performance in both hydrogen evolving and carbon dioxide reduction. The optimal T-CN catalyst exhibited the highest hydrogen evolution rate of 80.9 ± 1.3 μmol·h and carbon monoxide production rate of 8.1 ± 0.2 μmol·h, which are ca. 8-fold and 20-fold of bulk CN, respectively. The convenient strategy of constructing D-A conjugated structure opens up a new intriguing avenue toward the rational creation of efficient polymeric nanomaterials for versatile applications of solar fuel production.