Exploring the Potential of Lanthanum-Doped ZnFe₂O₄ Nanomaterials as Electrode Materials for Next-Generation Supercapacitors

In this study, we synthesized ZnFe_2-xLa_xO₄ nanoparticles with varying lanthanum (La) content (x = 0, 0.01, 0.03, 0.05) via a cost-effective combustion method utilizing citric acid as a fuel. This method was selected for its cost-effectiveness and its capability to produce high-quality nanoparticles with tailored properties. X-ray diffraction (XRD) analysis confirmed the cubic structure of the synthesized ZnFe₂O₄ product, revealing planes (220), (311), (400), (511), and (440) within the Fd-3m space group, with no additional peaks observed, indicating phase purity. The study proceeded to calculate essential parameters including lattice parameter, particle size, and strain, utilizing the Williamson–Hall method, offering important insights into the structural features and behaviors of synthesized nanoparticles. The crystallite size and surface morphology were investigated by TEM analysis. Additionally, Raman spectroscopy revealed five distinct Raman-active modes (A1g + Eg + 3F2g), consistent with the spinel structure. The electrochemical properties of the electrodes were assessed using a three-electrode system in a 2 M KOH electrolyte, employing cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). At a scan rate of 2 mV/s, a specific capacitance of 109.58 F/g was achieved with the nanomaterial synthesized via the combustion technique.