Thursday 18 Oct 2012FMG Seminar: Chemical control of graphene architecture and impact on applications

Professor Ray Whitby (Brighton) - Nanoscience and Nanotechnology Group, Faculty of Science and Engineering, University of Brighton

HAR/170 (3D Visualisation Suite) 14:00-15:00

Acid-oxidation of graphite followed by additional chemical treatment and sonication, as a variation of the Hummer's method, generates single-layer graphene oxide (SLGO) with an extensive number and variety of oxygen containing groups across the surface and along the periphery of each sheet, which improves hydrophilicity. Each SLGO sheet is negatively charged when dispersed in aqueous solution due to the oxygen-containing groups being ionized. The stability of aqueous SLGO colloids was therefore attributed to electrostatic repulsion between adjacent sheets rather than just hydrophilic interaction with the surrounding aqueous solution [1]. This is further demonstrated through the ability to "salt out" SLGO by overcoming the electrostatic repulsion, leading to SLGO sedimentation [2]. The colloidal dispersion becomes useful for exerting environmental changes and conducting chemical reactions that can manipulate the interface between solution and graphene, altering the architecture of SLGO [3]. This allows greater flexibility of use of SLGO, where the architecture will influence the final physicochemical properties of modified SLGO and its composites [4]. Herein, SLGO are explored through chemical reactivity, exploiting the oxygen-containing acidic groups, to drive conformational changes and how carefully selected chemistry can directly influence the nano- to marco-scale geometry and in turn their potential applications.

Acknowledgement: The author thanks the support obtained from the EC Seventh Framework Programme (FP7/2007-2013), Marie Curie International Research Staff Exchange Scheme (grant no. 230790), Marie-Curie Industry-Academia Partnerships and Pathways Agreement (PIAP-GA-2008-218242) for financial support, the RCUK Academic Fellowship Scheme and CheapTubes Inc for useful discussions.

References:
[1] D. Li, M.B. Muller, S. Gilje, R.B. Kaner, G.G. Wallace, Nature Nanotechnology, 3, 101 (2008)
[2] R.L.D. Whitby, A. Korobeinyk, K.V. Glevatska, Carbon, 49, 722 (2011)
[3] R.L.D. Whitby, V.M. Gun'ko, A. Korobeinyk, R. Busquets, A.B. Cundy, K. Laszlo, J. Skubiszewska-Zieba, R. Leboda, E. Tombacz, I.Y. Toth, K. Kovacs and S.V. Mikhalovsky, ACS Nano, 6, 3967 (2012)
[4] R.L.D. Whitby, A. Korobeinyk, S.V. Mikhalovsky, T. Fukuda and T. Maekawa, Journal of Nanoparticle Research, 13, 4829 (2011)

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