Table of Contents
Journal of Nanoparticles
Volume 2014, Article ID 640281, 6 pages
http://dx.doi.org/10.1155/2014/640281
Research Article

Aqueous Colloidal Stability of Graphene Oxide and Chemically Converted Graphene

1Department of Ceramic Engineering, National Institute of Technology Rourkela, Odisha 769 008, India
2Department of Ceramic Engineering, Indian Institute of Technology BHU, Varanasi, Uttar Pradesh 221 005, India

Received 6 August 2014; Revised 24 October 2014; Accepted 24 October 2014; Published 13 November 2014

Academic Editor: Vijaya Rangari

Copyright © 2014 Swarnima Kashyap et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Graphene oxide (GO) was prepared by modified Hummer’s method, and chemically converted graphene (CCG) was prepared by further reduction of the aqueous GO colloid. The effect of pH on particle size, particle charge, and light absorption of the aqueous colloids of GO and CCG was studied with titration against HCl or NaOH, to find the ideal characteristics for a stable dispersion. The GO colloid was stable in the pH range of 4–11, whereas the CCG colloid gained stability at a relatively narrower pH range of 7–10. Poor stability of the colloids was observed for both GO and CCG colloids at both extremes of the pH scale. Both of the colloids exhibited average size of ~1 micron in the low pH range, whereas for higher pH the size ranged between 300 and 500 nm. The UV-Vis spectra showed absorption peak at 230 nm for GO colloids that shifted to 260 nm for the CCG colloid. Such shift can be ascribed to restoring of electronic conjugation of the C=C bonds in CCG.