Date of Award

8-1-2011

Degree Name

Master of Science

Department

Physics

First Advisor

Talapatra, Saikat

Abstract

In this work we have investigated supercapacitor electrodes prepared from pure and 1-pyrenecarboxylic acid (PCA)-functionalized graphene flakes obtained from liquid phase chemical exfoliation method. The performances of the supercapacitor devices fabricated using the graphene electrodes were tested using cyclic voltammetry, constant current charging-discharging and by electrochemical impedance spectroscopy (EIS) The specific capacitances obtained (using 6M KOH aqueous solution as an electrolyte) were found to be ~ 30 F/g and ~ 200 F/g for pure graphene and PCA functionalized graphene electrodes respectively. A comprehensive understanding of the effect of surface fictionalization on the electrochemical double layer capacitance was obtained in the light of equivalent circuit modeling and EIS data analysis. Information obtained from the EIS spectrum analysis revealed the possibility of occurrence of pseudocapacitance due to the presence of surface functional groups on the graphene flakes. Further, the wettability by KOH significantly increases upon functionalizing the graphene surfaces. These results shows PCA functionalized graphene membrane electrodes have the potential for high performance as supercapacitor electrode material.

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