Morphological and electrochemical study of iron oxide/carbon xerogel nanocomposites for supercapacitor

Abstract

A hybrid composite electrode for supercapacitor has been prepared from iron oxide and nanoporous carbon derived from polybenzoxazine. First, porous polybenzoxazine was prepared through a sol-gel process before pyrolysis under nitrogen gas at high temperature yielding nanoporous carbon. In order to improve an electrochemical performance of the electrodes, nanoporous carbon was underwent the heat treatment at 300°C in air to improve the wettability of the electrolyte on the surface of porous carbon. The BET surface area of the heat-treated carbon xerogel was approximately 372 m²/g. The cyclic voltammeter, galvanostatic charge/discharge, and electrochemical impedance spectroscopy were used to investigate the electrode performance. The results showed that the electrodes prepared from ploybenzoxazine-derived-carbon xerogel exhibited good electrochemical performance. A specific capacitance of the heat-treated carbon xerogel electrodes was 108 F/g obtained in 6M KOH at current density 5 mA/cm². In addition to the effect of the nanoporous carbon microstructure, the effect of iron oxide (Fe₃O₄) content (1, 3, and 5 wt.%) on the electrochemical properties of the composite electrodes was also investigated. Electrochemical characterization indicated that 3 wt.% Fe₃O₄-impregnated carbon xerogel with heat treatment showed the highest specific capacitance (120 F/g) due to the pseudocapacitive properties of iron oxide. The electrochemical impedance spectroscopy and cyclic voltammetry were also confirmed this electrochemical behavior.