• The nanospheres of Ce-doped ZnFe₂O₄ were synthesized via a solvent-free, citric acid-fueled auto-combustion method. • Band gap narrowing upon Ce doping enhanced electrical conductivity and charge transport properties. • The optimized nanoparticle achieved 422.85 F/g specific capacitance at 1 A/g as well as charge transfer resistance decreased markedly from 1.23 Ω to 0.97 Ω, indicating improved ion diffusion and interfacial kinetics. Cerium-doped zinc ferrite nanospheres (ZnFe 2-x Ce x O 4 ; x = 0.0, 0.01, 0.03, 0.05) were successfully synthesized via a citric acid-fueled auto-combustion method. To the best of our knowledge, this is the first time these nanospheres have been developed for dual applications in photocatalysis and supercapacitors. X-ray diffraction confirmed the formation of a crystalline spinel structure with successful incorporation of Ce ions into the ZnFe₂O₄ lattice. Microstructural analysis using Debye–Scherrer, Williamson–Hall, and size–strain plot methods, supported by transmission electron microscopy, revealed well-dispersed nanospheres with controlled crystallite size and lattice strain. Rietveld refinement and X-ray photoelectron spectroscopy further verified the structural parameters and oxidation states of the constituent elements. UV–Vis diffuse reflectance spectroscopy showed a red shift in the absorption edge and a reduced band gap upon Ce doping, indicating enhanced visible-light absorption. The optimized ZnFe 1.95 Ce 0.05 O 4 sample exhibited superior photocatalytic performance, achieving 93.84% degradation of methylene blue under visible light within 4 h and maintaining stable activity over repeated cycles. Electrochemical measurements in 2 M KOH electrolyte demonstrated pronounced pseudocapacitive behaviour with a high specific capacitance of 422.85 F g⁻¹ at 1 A g⁻¹ and reduced charge-transfer resistance, indicating improved conductivity and ion transport. These findings demonstrate that Ce-doped ZnFe₂O₄ nanostructures are promising bifunctional materials for photocatalytic pollutant degradation and high-performance supercapacitor electrodes.
Rai et al. (Wed,) studied this question.