1-Dimensional porous α-Fe2O3 nanorods as high performance electrode material for supercapacitors

Abstract

Porous α-Fe₂O₃ nanorods are successfully synthesized without any templates by a simple wet chemical synthesis method using ferrous sulphate (FeSO₄·7H₂O) and sodium acetate (CH₃COONa) as starting materials. In this method, initially obtained α-FeOOH is calcinated at 300 °C for 2 h to form 1-dimensional porous α-Fe₂O₃ nanorods. Thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HR-TEM) and a gas sorption analyzer are employed to characterize α-Fe₂O₃ porous nanorods. Based on the characterization results, a formation mechanism for α-Fe₂O₃ nanorods is proposed. Electrochemical performance of porous α-Fe₂O₃ nanorods is studied using cyclic (CV) voltammetry, galvanostatic charge/discharge measurements and electrochemical impedance spectroscopy (EIS) in aqueous H₃PO₄, (NH₄)₂SO₄ and Na₂SO₄ electrolytes. Interestingly, the porous α-Fe₂O₃ nanorod-based electrodes exhibit excellent electrochemical performance, which can be attributed to the high surface area induced by the 1-dimensional porous nanorod structures. The rod shape porous structure facilitates the faster faradic reaction toward electrolytes and delivers highest specific capacitance (308 F g⁻¹) and an excellent long cycle life (upto 1000 cycles) in H₃PO₄ electrolyte, demonstrating that the porous α-Fe₂O₃ nanorods can serve as an excellent electrode material for supercapacitors.