Rod-shaped aggregates of sulfur-doped carbon nitride nanosheets for enhanced photocatalytic hydrogen evolution

Synthesis of few-layer carbon nitride with wide absorption spectra is an interesting research area. Heteroatom doping, particularly sulfur (S) doping, can effectively prevent band gap widening triggered by the quantum confinement effect in nanoscale carbon nitride sheets. Herein, different from that in second calcination sulfuration, the presulfuration supramolecular precursors can in situ form the S-doped carbon nitride (SCN) nanosheet stacked microrods. This few-layer frame construction possesses a large specific surface area (139.06 m2 g−1), exposes more active sites, and facilitates the internal reflection of photons. Furthermore, the introduction of S distorts the conjugated structure of the original heptazine ring, narrowing the band gap of carbon nitride through the activation of the n→π⋆ transition in valence band electrons. Consequently, the light absorption range is extended to 700 nm. Finally, the hydrogen evolution rate of SCN0.8 (3925.8 µmol g−1 h−1) is 8.1 times that of bulk carbon nitride (485.2 µmol g−1 h−1) under simulated sunlight conditions (AM 1.5G). The stacking of sheets avoids the accumulation of nanosheets and enhances performance and structural stability. The proposed structure aims to maximize the utilization of synergistic effects of heteroatom doping and morphology regulation to improve photocatalytic hydrogen evolution. Furthermore, this work provides a new perspective for the multidimensional synchronous optimization of photocatalysts.