Graphene mechanically exfoliated graphen

The discussion in Sect. 4 of the Raman spectrum of bilayer and multilayer graphene is valid only for Bernal (AB) stacked graphene. Mechanically exfoliated graphene from crystalline graphite usually exhibits such characteristics. However, multilayer... 

The majority of studies have used surfactants that wrap around nanocarbons via van der Waals interactions [37]. For instance, surfactants such as sodium dodecylsulfate (SDS) are commonly used to disperse CNTs in aqueous solutions [38,39] while other surfactants, such as Pluorinc-123, are used to mechanically exfoliate graphene from graphite flakes (Fig. 5.4(a)) [40,41]. The polar head group of the surfactant can be used to further hybridize the nanocarbon via a range of covalent or noncovalent interactions [42]. For example, nanoparticles of Pt [43,44] and Pd [45] have been decorated onto SDS-wrapped MWCNTs. Similarly, Whitsitt et al. evaluated various surfactants for their ability to facilitate the deposition of Si02 NPs onto SWCNTs [46,47]. As an exam-... 

Toth, P.S., Valota, A., Velicky, M., Kinloch, I., Novoselov, K., Hill, E.W, and Dryfe, R.A.W. (2014) Electrochemistry in a drop a study of the electrochemical behaviour of mechanically exfoliated graphene on photoresist coated silicon substrate. Chem. Set, 5, 582- 589. 

Oxidized silicon is the most commonly used substrate because it provides enhanced optical visibility of graphene (Section 4) and can be used for transport measurements. However, mechanically exfoliated graphene has also been deposited on other substrates such as quartz, silicon, glass, sapphire, NiFe, and GaAs [57, 58] no strong effects on the Raman spectrum have been observed by using these substrates. 

It is common for mechanically exfoliated graphene not to have enough structural defects for the D peak to be clearly seen. This is indicative of the high crystallinity of graphene obtained by this technique. In this case, the D peak is only present at the edges. Fig. 9. An edge acts as defect on the Raman scattering process because it breaks the translation symmetry of the crystal. 

Bulk graphite oxide is best prepared from purified natural graphite using the Hummers method Hummers, W. S. Offeman, R. E. J. Am. Chem. Soc. 1958,80,1339. For the mechanical exfoliation of bulk graphene oxide into sheets within an aqueous medium, see Stankovich, S. Dikin, D. A. Dommett, G. H. B. Kohlhaas, K. M. Zimney, E. J. Stach, E. A. Finer, R. D. Nguyen, S. T. Ruoff, R. S. Nature 2006,442, 282. 

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