Highly Dispersed NiCo₂O₄ Nanodots Decorated Three-Dimensional g-C₃N₄ for Enhanced Photocatalytic H₂ Generation

Abstract

NiCo2O4 nanodots decorated graphitic carbon nitride (g-C3N4) heterojunction was synthesized based on the energy band matching theory for efficient photocatalytic hydrogen evolution reaction under simulated solar irradiation. NiCo2O4 species (Eg = 1.77 eV) are uniformly anchored on the surface of g-C3N4 for the formation of NiCo2O4/g-C3N4 heterojunction to enhance the light response of the hybrid catalyst. The NiCo2O4/g-C3N4 heterojunction generates more structure defects, favoring the photocatalysis by accelerating the separation and transfer of the photoexcited electrons and holes and suppressing the recombination of the photoinduced carries. At the heterojunction interface, the photogenerated electrons transfer from the conduction band of NiCo2O4 to that of g-C3N4, while the photogenerated holes transfer from the valence band of g-C3N4 to that of NiCo2O4, making more active electrons participate in the generation of hydrogen. Compared with the pristine g-C3N4 and NiCo2O4, a NiCo2O4/g-C3N4 heterojunction sample (NC-6%) shows a hydrogen generation rate at 462.4 μmol·g–1·h–1, reaching 2.2 times and 400 times higher than that of g-C3N4 and NiCo2O4, respectively.