Synthesis of graphene–NiFe2O4 nanocomposites and their electrochemical capacitive behavior

Abstract

Reduced graphite oxide–NiFe₂O₄ (RGO–NiFe₂O₄) composites were synthesized by adding different amounts of NH₃·H₂O into a mixed aqueous solution of graphite oxide, Ni(NO₃)₂ and Fe(NO₃)₃ at room temperature. NH₃·H₂O was used to adjust the synthesis system's pH value. The morphology and the microstructure of the as-prepared composites were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) and transmission electron microscope (TEM) techniques. The structure characterizations indicate that NiFe₂O₄ successfully deposited on the surface of the RGO and the morphologies of RGO–NiFe₂O₄ show a transparent structure with NiFe₂O₄ homogeneously distributed on the RGO surfaces. Capacitive properties of the synthesized electrodes were studied using cyclic voltammetry and electrochemical impedance spectroscopy in a three-electrode experimental setup using 1 M Na₂SO₄ aqueous solution as electrolyte. It is found that the pH value plays an important role in controlling the electrochemical properties of these electrodes. Among the synthesized electrodes, RGO–NiFe₁₀ (pH = 10) shows the best capacitive properties because of its suitable particle size and good dispersion property. It could be anticipated that the synthesized electrodes will gain promising applications as novel electrode materials in supercapacitors and other devices by virtue of their outstanding characteristics of controllable capacitance and facile synthesis.