Khanra, Partha and Lee, Chang-No and Kuila, Tapas and Kim, Nam Hoon and Park, Min Jun and Lee, Joong Hee (2014) 7,7,8,8-Tetracyanoquinodimethane-assisted onestep electrochemical exfoliation of graphite and its performance as an electrode material. Nanoscale, 6. pp. 4864-4873. ISSN 2040-3364

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A green approach for the preparation of water-dispersible functionalized graphene via one-step electrochemical exfoliation of graphite using 7,7,8,8-tetracyanoquinodimethane (TCNQ) anions as surface modifiers and electrolytes was described. TCNQ is an organic charge-transfer complex with electron accepting and noteworthy electrical properties. The exfoliation of graphite to a few-layer graphene sheets was confirmed by transmission electron microscopy (TEM) and atomic force microscopy (AFM) image analysis. The chemical state, surface functional groups and chemical compositions of bulk graphite as well as TCNQ-functionalized graphene sheets were investigated by Fourier-transform infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS) analysis. Adsorption of TCNQ onto the surface of graphene sheets was confirmed by the appearance of the N1s peak at _399.4 eV in the XPS of TCNQ-functionalized graphene. Exfoliation of bulk graphite to functionalized graphene sheets was further confirmed by the appearance of a sharp single peak at _2695 cm_1 along with increased intensity ratios of the D-band to the G-band. Electrochemical performance of a TCNQfunctionalized graphene sheet was investigated using 1 M Na2SO4 and 1 M KOH aqueous solutions. Cyclic voltammetry (CV) and galvanometric charge–discharge experiments revealed that TCNQfunctionalized graphene could be used as a supercapacitor electrode material. The specific capacitance values of TCNQ-modified graphene measured with electrolytes (1 M KOH and 1 M Na2SO4) were 324 and 140 F g_1, respectively, at a current density of 1 A g_1. Impedance spectroscopic analysis revealed that the charge transfer process was dependent on surface functionalization and interaction between the electrode and the electrolyte.

Item Type: Article
Subjects: Materials
Depositing User: Dr. Sarita Ghosh
Date Deposited: 15 Jan 2016 11:09
Last Modified: 15 Jan 2016 11:09

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