Heteroatom doping has been proven as an effective way to tailor the properties of graphene and render its potential use for energy storage devices. In this work, we report a facile method to synthesis of reduced graphene oxide (RGO) from graphite electrodes using ionic liquid-assisted electrochemical exfoliation and the competent doping of RGO by Chlorine (Cl-RGO) in solution phase. Its capacitive performance was calculated by cyclic voltammetry and charge–discharge cycling in 6M KOH solution. The characterization of synthesized catalysts has been investigation by FT-IR, Raman, XRD and XPS techniques. We have evaluated the effectiveness of doping and performed by electrochemical measurements (involving cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy). It was found that the chlorine groups making the as-prepared Cl-RGO exhibited remarkably enhanced electrochemical performance when used as electrode materials in supercapacitors. The supercapacitor based on the Cl-RGO exhibited a high specific capacitance of 180.5 F g-1 at current density of 1 A g-1 and remains a relatively high capacitance even at a high current density more than RGO.
