Photocatalytic Degradation of Rhodamine B Using ZnCo₂O₄/N-doped g-C₃N₄ Nanocomposite

In this study, g-C₃N_4, ZnCo₂O_4, N-doped g-C₃N₄, ZnCo₂O₄/g-C₃N₄ and ZnCo₂O₄/N-doped g-C₃N₄ nanopowders were synthesized by the hydrothermal method and applied as photocatalysts to degrade Rhodamine B under visible light illumination in an aqueous solution. The as synthesized nanostructures were characterized via FT-IR, XRD, FE-SEM, EDS, TEM, UV–Vis DRS, and BET/BJH techniques. The XRD analysis revealed the successful synthesis of cubic ZnCo₂O₄ and nanolayered g-C₃N₄. The BET/BJH analysis exhibited that all samples show a typical Type-III isotherm and H3-type hysteresis loops. The FTIR and EDX analyses validated the formation of the presumed nanomaterials. UV–Vis DRS results indicated that the loading of ZnCo₂O₄ on N-doped g-C₃N₄ effectively shifted absorption edge to longer wavelengths. The morphological study showed sufficient distribution of ZnCo₂O₄ nanoparticles onto g-C₃N₄ nanosheets. The photocatalytic degradation results show that photocatalytic performance can be enhanced by optimizing operating conditions, including irradiation time, catalyst dosage, RhB concentration and solution pH. The ZnCo₂O₄/N-doped g-C₃N₄ showed the highest photodegradation efficiency of 92.34% RhB degradation in 60 min illumination. In addition, the results of scavenging study indicate that hydroxyl radicals (^•OH) play a main role in the photodegradation process. The kinetic study demonstrates that the photodegradation of RhB follows pseudo first order kinetic model. The recyclability study showed that the ZnCo₂O₄/N-doped g-C₃N₄ nanocomposite retained 83.38% of its initial activity after reuse for five cycles. Furthermore, at optimum conditions, the COD removal efficiency was 79.55%, indicating that most of dye molecules are degraded. Therefore, the current designed system can be regarded as an efficient and effective approach for the remediation of water contaminants.