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.