Core-shell structure carbon coated ferric oxide (Fe sub(2)O sub(3)C) nanoparticles for supercapacitors with superior electrochemical performance

Core-shell structure carbon coated ferric oxide nanoparticles (Fe sub(2)O sub(3)C) were fabricated by the oxidation of carbon coated iron nanoparticles (Fe[at]C) prepared by a direct current carbon arc discharge method. Porous activated-Fe sub(2)O sub(3)C was prepared by KOH activation of Fe sub(2)O sub(3)C at the temperature of 750 [degrees]C. X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to characterize the structure and morphology of the Fe sub(2)O sub(3)C and activated-Fe sub(2)O sub(3)C. The specific surface area and pore size distribution of the samples were also tested. The activated-Fe sub(2)O sub(3)C electrodes exhibited good electrochemical performance with a maximum specific capacitance of 612 F g super(-1) at the charge/discharge current density of 0.5 A g super(-1) with 5 M NaOH electrolyte. After 10,000 cycling DC tests at the charge/discharge current density of 4 A g super(-1), a high level specific capacitance of 518 F g super(-1) was obtained (90.6% retention of the initial capacity), suggesting excellent long-term cycling stability.