Interfacial generation of plates assembled with alpha-Fe2O3 nano-flakes for electrochemical capacitors

Abstract

In this work, we report facile synthesis of two-dimensional plates formed by the assembly of iron oxide nano flakes for application in electrochemical capacitors. The alpha-Fe2O3 nano-flakes plates were synthesized by an interfacial reaction and a subsequent thermal treatment without employing any template or matrix for the self assembly. The flake size could be easily controlled by varying the duration for which the iron precursor (Fe(CO)(5)) underwent a reaction with the basic aqueous phase at the oil-water interface. The resulting plates were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FT-IR). The results indicated that the as-obtained materials were hematite (alpha-Fe2O3). The thickness and edge size of the nano-flakes were in the range of 30-50 nm and 200-800 nm, respectively. The electrochemical properties of alpha-Fe2O3 nano flakes plates were systematically investigated by means of cyclic voltammetry (CV), galvanostatic charge/discharge cycling, and electrochemical impedance spectroscopy (EIS). The highest specific capacitance of 171 F g(-1), was obtained for the NF-1 sample whose average flake size was 250 nm and the thickness was 30 nm. Capacitance retention of the NF-1 sample after 1000 cycles was found to be 85% of the initial capacitance, indicating its good cycle stability. (C) 2016 Elsevier B.V. All rights reserved.