Solar light reduced Graphene as high energy density supercapacitor and capacitive deionization electrode

Graphene is a promising electrode material for high performance supercapacitors and capacitive deionization applications. Our present work is focused on the synthesis of graphene nanosheets by the reduction of graphite oxide using focused solar irradiation. The as prepared graphene nanosheets are characterized by Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray Photoelectron Spectroscopy (XPS) and Fourier transform infrared spectroscopic (FTIR) techniques for surface, structural and functional group analysis. Electrochemical properties are studied using cyclic voltammetry and galvanostatic charge-discharge method. The fabricated supercapacitor cell shows high specific capacitance of 265.9 and 187.1 F g−1 with 6 M KOH and ionic liquid electrolyte (EMIMBF4), respectively. High energy density of 58.5 Wh Kg−1 has been obtained for EMIMBF4 electrolyte. The electrosorption studies were also performed to study the effect of deionization behaviour of the prepared graphene under flow in between electrodes technique. The electrosortion capacity of 22.4 mg/g has been obtained for 100 mM NaCl (∼5844 mg/l) solution at the applied voltage of 1 V.