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- Widenkvist, Erika, et al.
(författare)
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Intercalation and Ultrasonic Treatment of Graphite : a New Synthetic Route to Graphene
- 2008
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Konferensbidrag (refereegranskat)abstract
- We will demonstrate that ultrasonic treatment of a graphite crystal in water can lead to the formation of small graphene-like flakes in solution. The delamination of the graphite can be increased dramatically by intercalation of bromine from a Br2-saturated water solution. After ultrasonic treatment, large amounts of graphene-like flakes with varying thickness are observed in SEM and TEM. They can be adsorbed onto a surface of a suitable substrate by a simple dipping technique. The effect of polar and non-polar solvents as well as adsorption of the graphene on hydrophobic and hydrophilic substrates will be demonstrated and compared. DFT calculations of the intercalation process have been carried out using the SIESTA package and the effect of bromine intercalation on cohesive energy and electronic structure will be discussed and compared with experimental data. Finally, the general approach of using ultrasonic treatment and intercalation as a facile route to graphene synthesis compared to other methods will be discussed.
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- Widenkvist, Erika, et al.
(författare)
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Mild sonochemical exfoliation of bromine-intercalated graphite a new route towards graphene
- 2009
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Ingår i: Journal of Physics D. - : IOP Publishing Ltd. - 0022-3727 .- 1361-6463. ; 42:11, s. 112003-
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Tidskriftsartikel (refereegranskat)abstract
- A method to produce suspensions of graphene sheets by combining solution-based bromine intercalation and mild sonochemical exfoliation is presented. Ultrasonic treatment of graphite in water leads to the formation of suspensions of graphite flakes. The delamination is dramatically improved by intercalation of bromine into the graphite before sonication. The bromine intercalation was verified by Raman spectroscopy as well as by x-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculations show an almost ten times lower interlayer binding energy after introducing Br2 into the graphite. Analysis of the suspended material by transmission and scanning electron microscopy (TEM and SEM) revealed a significant content of few-layer graphene with sizes up to 30 µm, corresponding to the grain size of the starting material
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- Yang, Wenzhi, et al.
(författare)
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The Functionalization of Graphene
- 2009
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Molecular functionalization of graphene is a key to materials applications. This could be by covalent and non-covalent strategies, the latter more interesting since this causes no damage to the carbon lattice, but also more challenging since this can be more difficult to detect by “standard” graphene methods such as Raman spectroscopy, microscopy (light, AFM, STM and TEM). Pyrene derivatives are established tools for non-covalent fuctionalization of carbon nano-tubes that should interact with Graphene in the same fashion.
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