Preparation and electrochemical capacitive behavior of graphene by microwave assisted thermal reduction of graphite oxide in hydrazine hydrate

Graphene platelets with a large scale have been synthesized by reduction of graphene oxide (GO) in aqueous solution of hydrazine hydrate under microwave irradiation (MWI). Microstructure of the graphene was characterized by X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy (AFM) and transmission electron microscopy (TEM) together with the selected area electron diffraction (SAED). The electrochemical properties were evaluated by the analysis of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in 1 M Na₂SO₄ aqueous solution. The results show that the as-prepared materials consist of crumpled, few-layer (∼ 3 nm) thick and electronically conductive graphitic sheets. The supercapacitors fabricated using this material possess a low equivalent series resistance (ESR) value ∼ 1.6ω and a high specific capacitance of 285 F · g^-1. In addition, the graphene reduced under a diverse duration of MWI displays a different interlayer spacing, extent of reduction, level of graphitization and specific capacitances. The duration of MWI and the treatment methods strongly affect the microstructure of graphene, and then dominate its electrochemical properties.