Spinel MnFe2O4 nanoparticles with improved surface area and charge transfer characteristics for next-generation supercapacitors

The growing demand for sustainable and efficient energy storage devices has accelerated the development of advanced electrode materials for high-performance supercapacitors. In this work, MnFe₂O₄ nanoparticles were successfully synthesized through a novel green co-precipitation approach using Curcuma longa extract as a natural reducing and stabilizing agent. XRD analysis confirmed the formation of highly crystalline spinel MnFe₂O₄ with an average crystallite size of 19.9 nm and excellent phase purity. Raman spectroscopy further validated the characteristic vibrational modes of the spinel ferrite structure, while BET analysis revealed an enhanced surface area with mesoporous characteristics favorable for ion diffusion. SEM images demonstrated porous cauliflower-like interconnected morphology, and EDX confirmed the homogeneous distribution of Mn, Fe, and O elements without impurities. Electrochemical studies exhibited remarkable pseudocapacitive behavior with a high specific capacitance of 295 F g⁻¹ at 0.8 A g⁻¹ and 87.3% capacitance retention after 5000 charge–discharge cycles. Furthermore, EIS analysis revealed low charge transfer resistance and enhanced ion diffusion kinetics, confirming the strong potential of green-synthesized MnFe₂O₄ for sustainable next-generation supercapacitor applications.