Iron Oxide-based Supercapacitor from Ferratrane Precursor via Sol–gel-Hydrothermal Process

In this study, ferratrane was used as a precursor to prepare iron oxide material via a sol–gel-hydrothermal process for supercapacitor applications. The mixed solution of ferratrane precursor and de-ionized water was transferred into a Teflon-lined stainless steel autoclave and kept at a constant temperature of 200 °C for 6 h. The as-prepared powder was annealed at 500 °C for 2 h under an ambient atmosphere. The as-prepared and annealed samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) techniques. The as-prepared powder has a single phase of cubic magnetite (Fe3O4) and then can be transformed into rhombohedral hematite (α-Fe2O3) by annealing at 500 °C for 2 h. The electrochemical properties of the resultant α-Fe2O3 nanoparticles were evaluated by cyclic voltammetry (CV) and galvanostatic charge–discharge in a three-electrode cell. The α-Fe2O3 nanoparticles showed the highest specific capacitance of 532.80 F/g at the current density of 1 A/g and the highest energy density of 74.00 Wh/kg at the power density of 0.50 kW/kg.