The synergistic effect of iron cobaltite compare to its single oxides as cathode in supercapacitor

Mixed transition metal oxides have attracted great attention in supercapacitors applications due to their better electrochemical performance than their single oxides. In this work, iron cobaltite (FeCo₂O₄) and its single metal oxides i.e. iron oxide (Fe₂O₃) and cobalt oxide (Co₃O₄) were synthesized by a simple hydrothermal process. The structural, spectroscopic and morphological properties were studied using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and field-emission scanning electron microscope (FESEM). XRD and FTIR results show the composition of the products. The obtained iron oxide was α-Fe₂O₃. FESEM images show that FeCo₂O₄ and its single metal oxides exhibit different morphology even though they were synthesized via similar method. The electrochemical properties of the α-Fe₂O₃, Co₃O₄ and FeCo₂O₄ electrodes were examined by cyclic voltammetry (CV), galvanostatic charge/discharge (GCD) and electrochemical impedance spectroscopy (EIS) in a 6 M KOH electrolyte solution. At comparable current density, the FeCo₂O₄ electrode has the highest specific capacitance (C_sp), followed by Co₃O₄ and α-Fe₂O₃. An asymmetric FeCo₂O₄/KOH/GO supercapacitor was fabricated. The supercapacitor exhibits maximum energy density of 14.5 Wh kg⁻¹ and maximum power density of 2177 W kg⁻¹. It demonstrates 60% rate capability after 1000 continuous charge-discharge cycles at 1 A g⁻¹.