Facile design of N-rich g-C₃N₅/NiFe2O4 heterojunction for visible-light-driven photo-Fenton RhB degradation and photocatalytic hydrogen evolution

The need for effective and eco-friendly solutions to address dye pollution and hydrogen (H2) generation has driven research into visible-light-responsive photocatalysts. This study presents the synthesis of a novel nanocomposite, combining triazole-derived graphitic carbon nitride (g-C₃N₅) with nickel ferrite (NiFe₂O₄), prepared through a facile wet-chemical approach using 3-amino,1,2,4-triazole as a precursor. This composite is specifically designed for visible-light-driven photo-Fenton-like dye degradation and H₂ evolution without the necessity for precious metal co-catalysts. Characterization techniques, including X-ray diffraction (XRD), confirmed the successful synthesis of the nanocomposite by revealing distinct peaks corresponding to both NiFe₂O₄ and g-C₃N₅, indicating phase purity. Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) demonstrated the uniform deposition of NiFe₂O₄ nanoparticles on the g-C₃N₅ nanosheets, while energy-dispersive X-ray (EDX) spectroscopy confirmed the presence of nickel and iron in the composite. The NiFe₂O₄/N-rich g-C₃N₅ composite possessed a surface area of 131.11 m²/g, which is two times higher than that of pure NiFe₂O₄. Enhanced optical absorption and charge separation resulting from heterojunction formation significantly improved its photocatalytic efficiency. The NiFe₂O₄/g-C₃N₅ composite achieved 97 % degradation of rhodamine B dye within 40 min of visible-light exposure, compared to 13 % and 41 % for pure NiFe₂O₄ and N-rich g-C₃N₅, respectively. Additionally, it demonstrated superior H2 production, yielding 3247 μmol/g after 4 h of visible-light irradiation, outperforming pure g-C₃N₅ (2550 μmol/g) and NiFe₂O₄ (1127 μmol/g). The photocatalytic mechanism was explored using a band potential diagram and elemental trapping experiments. This is the first demonstration of NiFe₂O₄/N-rich g-C₃N₅driving both photo-Fenton dye degradation and H₂ evolution without noble-metal co-catalysts. This work offers a viable pathway for developing efficient and scalable photocatalysts for environmental and energy applications.