Copper substitution in cobalt ferrites for tunable supercapacitive properties

Advanced materials engineering plays a crucial role in the development of high-performance energy storage devices. In this study, a single-phase copper-substituted cobalt ferrite (Cu_0.4Co_0.6Fe₂O₄) was synthesized via a tartaric acid-assisted auto-combustion method. The structural and morphological characteristics of the synthesized material were investigated using a suite of analytical techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, infrared (IR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The analysis confirmed the formation of a monophasic cubic inverse spinel structure with uniform particle distribution. The electrochemical performance of the material was evaluated using cyclic voltammetry, revealing a high specific capacitance of 256 F g⁻¹ at a scan rate of 5 mV s⁻¹. The enhanced electrochemical behavior is attributed to the synergistic effect introduced by copper substitution, which improves redox activity, facilitates faster ionic diffusion, and enhances charge transfer dynamics. These combined effects contribute significantly to the superior charge storage capacity, making Cu-substituted CoFe₂O₄ a promising electrode material for next-generation supercapacitor applications.