Core-shell structure carbon coated ferric oxide (Fe2O3@C) nanoparticles for supercapacitors with superior electrochemical performance

Core-shell structure carbon coated ferric oxide nanoparticles (Fe2O3@C) were fabricated by the oxidation of carbon coated iron nanoparticles (Fe@C) prepared by a direct current carbon arc discharge method. Porous activated-Fe2O3@C was prepared by KOH activation of Fe2O3@C at the temperature of 750 °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 Fe2O3@C and activated-Fe2O3@C. The specific surface area and pore size distribution of the samples were also tested. The activated-Fe2O3@C electrodes exhibited good electrochemical performance with a maximum specific capacitance of 612 F g−1 at the charge/discharge current density of 0.5 A g−1 with 5 M NaOH electrolyte. After 10,000 cycling DC tests at the charge/discharge current density of 4 A g−1, a high level specific capacitance of 518 F g−1 was obtained (90.6% retention of the initial capacity), suggesting excellent long-term cycling stability.