Carbon Nanofilm with a New Structure and Property

Horiuchi, Shigeo; Gotou, Takuya; Fujiwara, Masahiro; Sotoaka, Ryuji; Hirata, Masukazu; Kimoto, Koji; Asaka, Toru; Yokosawa, Tadahiro; Matsui, Y.; Watanabe, Kenji; Sekita, Masami

doi:10.1143/jjap.42.l1073

Cited by 110 publications

(85 citation statements)

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“…3(f) shows that the inner peaks {1100} are less intense than the outer ones {2110}, giving a ratio of I {1100} /I {2110} of less than 1 (~0.5), which is ascribed to bilayer graphene with predominantly AB stacking. This observation is consistent with previous computational results for graphene layers [30].…”

Section: Resultssupporting

confidence: 94%

Solvothermal-assisted exfoliation process to produce graphene with high yield and high quality

et al. 2009

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Monolayer and bilayer graphene sheets have been produced by a solvothermal-assisted exfoliation process in a highly polar organic solvent, acetonitrile, using expanded graphite (EG) as the starting material. It is proposed that the dipole-induced dipole interactions between graphene and acetonitrile facilitate the exfoliation and dispersion of graphene. The facile and effective solvothermal-assisted exfoliation process raises the low yield of graphene reported in previous syntheses to 10 wt% 12 wt%. By means of centrifugation at 2000 rpm for 90 min, monolayer and bilayer graphene were separated effectively without the need to add a stabilizer or modifi er. Electron diffraction and Raman spectroscopy indicate that the resulting graphene sheets are high quality products without any signifi cant structural defects.

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Section: Resultssupporting

confidence: 94%

Solvothermal-assisted exfoliation process to produce graphene with high yield and high quality

et al. 2009

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“…In approximately 30% of cases, the flakes consisted of one layer; monolayer graphene (figure 11). That these were definitely graphene monolayers could be confirmed by electron diffraction through the difference in intensity of 2110 and 1100 diffraction spots [134] .…”

Section: Solventsmentioning

confidence: 81%

Liquid‐Phase Exfoliation of Nanotubes and Graphene

Coleman

2009

Adv Funct Materials

592

536

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Many applications of carbon nanotubes require the exfoliation of the nanotubes to give individual tubes in the liquid phase. This requires the dispersion, exfoliation and stabilisation of nanotubes in a variety of liquids. In this paper we review recent work in this area, focusing on results from the author's group. We begin by reviewing stabilisation mechanisms before exploring research into the exfoliation of nanotubes in solvents, by using surfactants or biomolecules and by covalent attachment of molecules.The concentration dependence of the degree of exfoliation in each case will be highlighted. In addition we will discuss research into the dispersion mechanism for each dispersant type. Most importantly we have compared dispersion quality metrics for all dispersants. From this analysis, we conclude that functionalised nanotubes can be exfoliated to the greatest degree. Finally, we review the extension of this work to the liquid phase exfoliation of graphite to give graphene.

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“…This is an important observation, as for graphene multi-layers with Bernal (AB) stacking, computational studies have shown that the intensity ratio, I {1100} /I {2100} <1, while for mono-layers I {1100} /I {2100} >1. 33 Virtually all the objects identified in all the images as multi-layers displayed I {1100} /I {2100} <1, demonstrating that Bernal stacking rather than AA stacking is predominant in these samples 33 .…”

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confidence: 96%

High-yield production of graphene by liquid-phase exfoliation of graphite

et al. 2008

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Graphene is at the centre of nanotechnology research. In order to fully exploit its outstanding properties, a mass production method is necessary. Two main routes are possible: large-scale growth or large-scale exfoliation. Here, we demonstrate graphene dispersions with concentrations up to ~0.01 mg/ml by dispersion and exfoliation of graphite in organic solvents such as N-methylpyrrolidone. This occurs because the energy required to exfoliate graphene is balanced by the solvent-graphene interaction for solvents whose surface energy matches that of graphene. We confirm the presence of individual graphene sheets with yields of up to 12% by mass, using absorption spectroscopy, transmission electron microscopy and electron diffraction. The absence of defects or oxides is confirmed by X-ray photoelectron, infra-red and Raman spectroscopies. We can produce conductive, semi-transparent films and conductive composites. Solution processing of graphene opens up a whole range of potential large-scale applications from device or sensor fabrication to liquid phase chemistry. Hernandez et al 2Graphene is one of the most exciting nano-materials due to the cascade of unique physical properties that have recently been demonstrated. For example, due to the details of its electronic structure, charge carriers in graphene behave as massless Dirac fermions 1 . Furthermore, novel effects such as an ambipolar field effect 2 , room temperature quantum Hall effect 3 , breakdown of the Born-Oppenheimer approximation 4 are observed. However, as was the case in the early days of nanotube and nanowire research, graphene at present still suffers from one problem, critical for its mass-scale exploitation: it cannot yet be made with high yield. The standard procedure used to make graphene is micromechanical cleavage 5 . This yields the best samples to date, with mobilities up to 200,000 cm 2 /Vs. 6 However, single layers are a negligible fraction amongst large quantities of thin graphite flakes. Furthermore, it is difficult to see how to scale up this process to mass production. Alternatively, growth of graphene is also commonly achieved by annealing SiC substrates, but these samples are in fact composed of a multitude of domains, most of them sub-micrometer, and not spatially uniform in number, or in size over larger length scales 7 . A number of works have also reported graphene growth on metal substrates 8,9 , but this would require the sample transfer to insulating substrates in order to make useful devices, either via mechanical transfer or, via solution processing.Recently, a large number of papers have described the dispersion and exfoliation of graphene oxide (GO) [10][11][12][13] . This material consists of graphene-like sheets, chemically functionalised with compounds such as hydroxyls and epoxides, which stabilise the sheets in water 14 . However, this functionalisation results in considerable disruption of the electronic structure of the graphene. In fact GO is an insulator 15 rather than a semi-metal and is conceptually differen...

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Carbon Nanofilm with a New Structure and Property

Cited by 110 publications

References 0 publications

Solvothermal-assisted exfoliation process to produce graphene with high yield and high quality

Solvothermal-assisted exfoliation process to produce graphene with high yield and high quality

Liquid‐Phase Exfoliation of Nanotubes and Graphene

High-yield production of graphene by liquid-phase exfoliation of graphite

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