Designing a novel highly efficient magnetic binary NiFe2O4/CeO2 nano-photocatalyst for visible-light-driven degradation of organic pollutants

Herein, novel magnetic binary NiFe₂O₄/CeO₂ nanocomposites were simultaneously prepared via simple sol–gel auto-combustion method serving as an efficient photocatalyst toward dye degradation under visible light illumination. Various gelation agents, including tetraethylenepentamine (TEPA), ammonia (NH₃), ethylene diamine (EN), and sodium hydroxide (NaOH), were employed to evaluate their influence on the purity and particle size of the NiFe₂O₄/CeO₂ nanocomposite. The designed nanocomposite was investigated through its performance in the photodecomposition of eosin (EO) and malachite green (MG) dyes. The results exposed that the anionic dye is degraded much more efficiently than cationic dye. The as-prepared photocatalyst displayed remarkable photocatalytic performance, with a 95% efficiency in degrading EO and a comparatively lower efficiency of 68.29% for MG. The pseudo-first-order kinetic model has been identified as the most appropriate for describing the adsorption of dyes onto the photocatalyst. The rate constant (k) for decolorization of EO over a period of 120 min using NiFe₂O₄/CeO₂ photocatalyst was determined to be 0.02798 min⁻¹. The magnetic characteristics of NiFe₂O₄/CeO₂ showed ferromagnetic behavior, which enhances the recovery of catalyst from water, suggesting a valuable opportunity in the practical applications. Besides, the mechanism of photocatalytic degradation was examined through scavenger experiments, which revealed the reactive radicals involved, emphasizing the crucial effect of ·O₂^– radicals in this procedure. The influence of the initial dye concentration and amount of photocatalyst on the degradation efficiency was also examined thoroughly. Moreover, the recyclability of the photocatalyst was verified over five repeated cycles, demonstrating its good stability.