Ultrathin porous sulfur, oxygen co-doped graphitic carbon nitride nanosheets for improved photocatalytic activity

Regulating the electronic structure and morphology of photocatalysts serves as an effective strategy for significantly enhancing their photodegradation efficiency. Herein, we develop a facile supramolecular self-assembly route followed by low-temperature heat treatment to synthesize ultrathin porous sulfur, oxygen co-doped g-C₃N₄ (S,O-GCN) nanosheets. This method simultaneously achieves heteroatom doping and structural engineering at a low synthesis temperature of 450 °C. The S,O-GCN delivers a high specific surface area of 123 m² g^-1, an ultrathin layer thickness of 0.9 nm, and a narrowed bandgap of 2.60 eV. Moreover, photoluminescence spectroscopy, photocurrent intensity, and electron paramagnetic resonance spectroscopy demonstrate an outstanding charge separation and transfer efficiency of the S,O-GCN catalyst. Benefiting from these structural and electronic merits, the S,O-GCN achieves nearly complete degradation of rhodamine B within 40 min under visible light irradiation, along with excellent cycling stability, maintaining robust stability. The corresponding first-order kinetic constant is calculated to be 0.18718 min^-1, which is 5.6-fold higher than that of pristine GCN (0.03321 min^-1). This work offers feasible guidance for the development of high-performance, low-cost g-C₃N₄-based catalysts for addressing practical environmental challenges.