Construction of Graphitic C3N4-Based Intramolecular Donor–Acceptor Conjugated Copolymers for Photocatalytic Hydrogen Evolution

The construction of intramolecular donor–acceptor conjugated copolymers has been devised for years to enhance the mobility of charge carriers in an organic photovoltaic field; however, surprisingly, similar strategies have not been reported in polymeric photocatalytic systems for promoting the separation of charge carriers. Graphitic carbon nitride (g-C3N4) is an emerging polymeric visible-light photocatalyst with high stability but still low photocatalytic efficiency. Here, we prepared a series of g-C3N4-based intramolecular donor–acceptor copolymers (aromatics-incorporated g-C3N4) via nucleophilic substitution/addition reactions. The copolymer showed remarkably enhanced and stable visible-light photocatalytic hydrogen evolution performance. The intramolecular charge transfer transition is first proposed to explain the photocatalytic activity of g-C3N4-based photocatalysts under long-wavelength-light irradiation.