The Role of Cerium(III) in Enhancing the Photocatalytic Performance of NiFe 2– x Ce x O 4 Nanostructures: Methyl Orange Degradation and Stability Assessment

High Resolution Image Download MS PowerPoint Slide Spinel NiFe 2– x Ce x O 4 nanoparticles ( x = 0, 0.2, 0.4, and 0.6) were synthesized via a modified sol–gel-assisted precipitation method followed by calcination at 500 °C. Their structural, morphological, optical, and electronic properties were systematically investigated using a comprehensive set of characterization techniques, including X-ray diffraction, electron microscopies (FESEM and TEM), X-ray photoelectron spectroscopy, thermogravimetric analysis, surface area measurements (BET method), optical spectroscopy, and electrochemical methods. The photocatalytic performance was evaluated through the degradation of methyl orange under visible light irradiation. All samples ( x = 0–0.4) exhibited a single-phase cubic spinel structure. Incorporation of Ce 3+ into the NiFe 2 O 4 lattice induced slight lattice distortion, reduced crystallite size, and increased the specific surface area. Thermal analysis revealed enhanced stability upon Ce doping, with the decomposition onset temperature shifting significantly at intermediate compositions. Among the investigated samples, NiFe 1.6 Ce 0.4 O 4 demonstrated the most favorable physicochemical properties, including the highest surface area, the smallest crystallite size, and the narrowed band gap of 1.90 eV. A marked decrease in photoluminescence intensity, together with enhanced photocurrent response and reduced charge transfer resistance, indicated efficient suppression of charge carrier recombination. A quantitative assessment based on normalized kinetic parameters and a combined performance index revealed that the superior photocatalytic activity arises from the synergistic interplay between structural, optical, and electronic factors. Under visible light irradiation, NiFe 1.6 Ce 0.4 O 4 achieved 99.2% degradation of methyl orange within 60 min, with a rate constant of 0.0432 min –1, outperforming the other compositions. The photocatalyst also exhibited excellent stability, retaining 96.5% of its initial activity after four cycles. These results demonstrate that controlled Ce 3+ substitution is an effective strategy for tuning the physicochemical properties of nickel ferrite and enhancing its visible-light-driven photocatalytic performance, highlighting the potential of NiFe 2– x Ce x O 4 nanostructures for sustainable wastewater treatment applications.