High concentration few-layer graphene sheets obtained by liquid phase exfoliation of graphite in ionic liquid

Nuvoli, Daniele; Valentini, Luca; Alzari, Valeria; Scognamillo, Sergio; Bon, Silvia Bittolo; Piccinini, M.; Illescas, Javier; Mariani, Alberto

doi:10.1039/c0jm02461a

Cited by 357 publications

(247 citation statements)

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“…[36][37][38][39][40][41][42][43][44][45][46][47] This work has contributed greatly to our understanding of the dispersion process, our practical approach to dispersion and the number of solvents available to graphene researchers.…”

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confidence: 99%

Liquid Exfoliation of Defect-Free Graphene

2012

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Due to its unprecedented physical properties, graphene has generated huge interest over the last 7 years. Graphene is generally fabricated in one of two ways: as very high quality sheets produced in limited quantities by micromechanical cleavage or vapour growth, or a rather defective, graphenelike material, graphene oxide, produced in large quantities. However, a growing number of applications would profit from the availability of a method to produce high quality graphene in large quantities.This Account describes recent work to develop such a processing route inspired by previous theoretical and experimental studies on the solvent-dispersion of carbon nanotubes. That work had shown that nanotubes could be effectively dispersed in solvents whose surface energy matched that of the nanotubes. We describe the application of the same approach to the exfoliation of graphite to give graphene in a range of solvents. When graphite powder is exposed to ultrasonication in the presence of a suitable solvent, the powder fragments into nanosheets, which are stabilized against aggregation by the solvent. The enthalpy of mixing is minimized for solvents with surface energies close to that of graphene (~68 mJ/m 2 ). The exfoliated nanosheets are free of defects and oxides and can be produced in large quantities. Once solvent exfoliation is possible, the process can be optimized and the nanosheets can be separated by size. The use of surfactants can also stabilize exfoliated graphene in water, where the zeta potential of the surfactant-coated graphene nanosheets controls the dispersed concentration.Liquid exfoliated graphene can be used for a range of applications: graphene dispersions as optical limiters, films of graphene flakes as transparent conductors or sensors, and exfoliated graphene as a mechanical reinforcement for polymer-based composites. Finally, we have extended this process to exfoliate other layered compounds such as BN and MoS 2 . Such materials will be important in a range of applications from thermoelectrics to battery electrodes. This liquid exfoliation technique can be applied to a wide range of materials and has the potential to be scaled up into an industrial process. We believe the coming decade will see an explosion in the applications involving liquid exfoliated two dimensional materials.J.N. Coleman, Liquid exfoliation of defect free graphene, Accounts of Chemical Research 2

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confidence: 99%

Liquid Exfoliation of Defect-Free Graphene

2012

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“…It also offers graphene yields as high as 5.33 mg/mL. Because of the use of an ionic liquid (1-hexyl-3-methyl-imidazolium hexafluorophosphate or HMIH), this process is stable and green [51]. Sodium dodecylbenzene sulfonate (SDBS) also tends to stabilize graphene layers and keeps them from aggregation [53].…”

Section: Sonicationmentioning

confidence: 99%

“…), where graphene can be separated from graphite with the help of centrifugation [49]. NMP or other ionic liquid can be used in such process [50,51]. A singlecycle yield of up to 5 % is obtainable from this process and about 70 % of the graphene obtained by this process is 1 nm thick having electrical conductivity of up to 5000 S·m −1 [52].…”

Section: Sonicationmentioning

confidence: 99%

Graphene synthesis: a Review

Shams

Zhang

Zhu

2015

Materials Science-Poland

132

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Graphene has achieved a great amount of popularity and interest from the science world because of its extraordinary physical, mechanical and thermal properties. Graphene is an allotrope of carbon, having one-atom-thick planar sheets of sp 2 bonded carbon atoms densely packed in a honeycomb crystal lattice. Many methods to synthesize graphene have been developed over a short period and we believe it is necessary to create a list of the most notable approaches. This article focuses on the methods to synthesize graphene in an attempt to summarize and document advancements in the synthesis of graphene research and future prospects.

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“…Zheng et al has reported solvothermal route to prepare graphene by direct exfoliation using oleylamine as a solvent as well as stabilizing agent [16]. Nuvoli et al has used a commercial ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate (HMIH), as a convenient solvent medium for graphite exfoliation in mild and easy conditions without any chemical modification [17]. This method resulted in few layer graphene with a concentration as high as 5.33 mg/ml, which is the highest value reported so far in any solvent.…”

Section: Introductionmentioning

confidence: 99%