Enhanced energy storage in supercapacitors: A study of chemically synthesized ferrite nanoparticles with optimized electrochemical properties

Herein, the impact of pH on ferrite nanoparticles (NPs) was synthesized using a simple chemical co-precipitation process and utilized for supercapacitor (SCs) applications. The X-ray analysis supports the stable phase formation and cubic crystal structures of Fe₃O₄-NPs. The scanning electron microscope (SEM) revealed irregular and non-uniformly shaped (NPs) signifying the important role in electrochemistry. Further, Fourier transform infrared and Raman spectroscopy confirm the presence of various functional groups and the stretching-bending vibrations between Fe–O, and O–O bonds, respectively. In addition to this, the X-ray photoelectron spectroscopy (XPS) reveals the presence of various oxidation states of the Fe in the prepared Fe₃O₄ NPs. Additionally, the specific surface area (SSA) and pore size of prepared Fe₃O₄ (pH-12) were determined using N₂ adsorption/desorption and it shows the SSA of 33.45 m²/g, and the average pore radius of 11.23 nm, respectively. Additionally, the electrochemical measurements of the prepared electrodes were examined using an electrode cell system in 1 M KOH electrolyte. Among all samples, the Fe₃O₄ (pH-12) shows better electrochemical properties such as a high specific capacitance and capacity values of 520 F/g (57 mAh/g) at 5 mA/cm². Further, the Fe₃O₄ (pH-12) sample exhibits better capacitance retention of 84 % over 4000 CV cycles. In addition to this, the fabricated device shows better electrochemical properties in terms of energy and power densities of 12 Wh/kg and 700 W/kg at 3 mA/cm² with 88 % retention over 3000 cycles. Therefore, this study explores the better electrochemical analysis for Fe₃O₄ NPs in SCs applications.