Electrochemical evaluation of the performance of cathodically grown ultra-fine magnetite nanoparticles as electrode material for supercapacitor applications

Ultra-fine nanoparticles of magnetite iron oxide (Fe₃O₄) were prepared through a poly(vinyl alcohol) (PVA) assisted cathodic electrosynthesis. According to this method, Fe₃O₄ was deposited on a stainless steel cathode form an aqueous electrolyte containing 0.005 M Fe(NO₃)₃/FeCl₂ and 0.1 g/L PVA. The structural characterization of the electro-synthesized deposit through X-ray diffraction (XRD), field emission and transmission electron microscopies (FE-SEM and TEM) confirmed that the product was composed of pure magnetite spherical particles with average size of 5 nm. The surface area of the resulting Fe₃O₄ nanoparticles was determined to be 171.5 m²/g through Brunauer–Emmett–Teller (BET) gas-sorption measurements. The electrochemical performance of the prepared ultra-fine nanoparticles was evaluated using cyclic voltammetry(CV), continuous charge–discharge (GCD) and electrochemical impedance spectroscopy (EIS) techniques. The obtained electrochemical data showed that the prepared Fe₃O₄ nanoparticles had suitable charge storage ability with a specific capacitance of as high as 195.8 F g⁻¹, and they maintain about 94% of their initial capacity after 3000 cycles at a current load of 0.5 A g⁻¹. These data proved the suitability of the prepared nanoparticles for use in supercapacitors. Furthermore, this work provides a facile electrochemical route for the synthesis of ultra-fine iron oxide nanoparticles for application in the next generations of energy storage materials.