Synthesis and Photocatalytic Performance of Nanocrystalline NiFe₂O₄ Synthesized via an Eco-Friendly Sol–Gel Route

Materials have become more and more important in a variety of businesses in recent years, going well beyond their conventional uses in day-to-day living. Over the past few decades, metal oxides and mixed metal oxides (MMOs) have drawn a lot of interest as effective and environmentally suitable substitutes for a variety of chemical, food, dye, and pharmaceutical sectors as well as for environmental remediation. The remarkable magnetic, electrical, and catalytic properties of nickel ferrite (NiFe₂O₄), a technologically significant spinel ferrite, have garnered significant interest. Using nickel nitrate, ferric nitrate, and Triton X-100 as a surfactant, the environmentally friendly sol–gel process was effectively used in this study to create nanocrystalline NiFe₂O₄. FT-IR analysis revealed distinctive tetrahedral and octahedral vibration bands at 774 and 668 cm⁻ 1 , respectively, supporting the structural confirmation of the spinel phase. SEM micrographs showed homogenous agglomerated nanostructures, while optical investigations showed a direct band gap of 2.0 eV. Under UV irradiation, the photocatalytic efficiency of NiFe₂O₄ was assessed for the breakdown of indigo carmine (IC) dye. At a catalyst dose of 30 mg and pH 4.5–5, complete degradation of IC dye (≈99%) was accomplished in 30 min. The oxidative cleavage of chromophoric linkages, which led to mineralisation into carbon dioxide and water, was verified by LC-MS analysis. Over the course of five successive cycles, the catalyst maintained high activity and stability, exhibiting exceptional reusability. These results show that NiFe₂O₄ produced from sol–gel is an effective, recyclable, and sustainable photocatalyst for removing organic dye contaminants from aqueous environments.