Hydrothermally Induced Oxygen Doping of Graphitic Carbon Nitride with a Highly Ordered Architecture and Enhanced Photocatalytic Activity

As an amorphous or semicrystalline material, graphitic carbon nitride (g‐C3N4) displays poor photocatalytic activity owing to rapid recombination of the photogenerated charge carriers, which is mainly caused by a high density of defects in the graphitic structure. In this work, a porous O‐doped g‐C3N4 (P‐CNO) nanosheet with a highly ordered architecture is fabricated by introducing a novel hydrothermal treatment to the precursor before the final thermal condensation. The photocatalytic hydrogen evolution rate (HER) and HER per surface area of P‐CNO are 13.9 and 1.7 times higher than that of bulk g‐C3N4. The improved photocatalytic activity is ascribed to a synergistic effect of O doping, a porous sheet‐like morphology, and increased crystallinity. This work also provides a new approach for the synthesis of other polymer‐based photocatalysts with high crystallinity and excellent performance.