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Journal of Engineering
Volume 2013, Article ID 638576, 10 pages
http://dx.doi.org/10.1155/2013/638576
Research Article

High Temperature Vacuum Annealing and Hydrogenation Modification of Exfoliated Graphite Nanoplatelets

1The Composite Materials and Structures Center, Department of Chemical Engineering and Materials Science, Michigan State University, 2100 Engineering Building, East Lansing, MI 48824, USA
2Department of Civil Engineering, University of Mississippi, 106 Carrier Hall, University, MS 38677, USA
3Engineering and Process Science, The Dow Chemical Company, Midland, MI 48674, USA

Received 14 January 2013; Accepted 31 July 2013

Academic Editor: Jong M. Park

Copyright © 2013 Xiaobing Li 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

Highly active defect sites on the edges of graphene automatically capture oxygen from air to form various oxygen groups. A two-step procedure to remove various oxygen functional groups from the defect sites of exfoliated graphene nanoplatelets (GNPs) has been developed to reduce the atomic oxygen concentration from 9.5% to 4.8%. This two-step approach involves high temperature vacuum annealing followed by hydrogenation to protect the reduced edge carbon atoms from recombining with the atmospheric oxygen. The reduced GNPs exhibit decreased surface resistance and graphitic potential-dependent capacitance characteristics compared to the complex potential-dependent capacitance characteristics exhibited by the unreduced GNPs as a result of the removal of the oxygen functional groups present primarily at the edges. These reduced GNPs also exhibit high electrochemical cyclic stability for electrochemical energy storage applications.