Liquid-phase exfoliation, functionalization and applications of graphene

Xu, Chonghai; Zhang, Chenzhen; Hao, Rui; Hou, Yanglong

doi:10.1039/c1nr10127g

Cited by 261 publications

(175 citation statements)

References 114 publications

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“…4,[15][16][17] The sonic energy tends to exfoliate 18 the crystals to give nanosheets stabilised against aggregation by interaction with the liquid. 15 The stabilising liquids can be certain solvents 16,17,[19][20][21][22][23][24][25][26][27][28][29][30] or solvent blends 31,32 , aqueous surfactant solutions 33-36 or polymer solutions. 37,38 Both surfactant-and polymer-stabilisation are due to repulsive forces between adjacent polymer-or surfactant-coated nanosheets.…”

Section: Introductionmentioning

confidence: 99%

Production of Molybdenum Trioxide Nanosheets by Liquid Exfoliation and Their Application in High-Performance Supercapacitors

et al. 2014

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ABSTRACT:Here we demonstrate a simple method to exfoliate layered molybdenum trioxide (MoO3) crystallites to give multi-layer MoO3 nanosheets dispersed in solvents. Exfoliation is achieved by sonicating MoO3 powder in the presence of suitable solvents followed by centrifugation to remove undispersed material. This procedure works well in a range of solvents with Hildebrand solubility parameters close to 21 MPa 1/2 , and is consistent with the predictions of classical solubility theory. We have fully optimised this process and demonstrated methods to separate the resultant nanosheets by size. Raman spectroscopy suggests the exfoliation process does not damage the MoO3. This is supported by measurements which show reaggregated nanosheets to display very similar photoluminescence to bulk MoO3. However, the dispersed nanosheets had distinctly different photoluminescence indicating a decoupling of the monolayers on exfoliation. We have used liquid exfoliated MoO3 to prepare supercapacitor electrodes which had relatively low capacitance (~2 F/g at 10 mV/s), due to the low electrical conductivity of the MoO3.However, addition of carbon nanotubes beyond the percolation threshold yielded a 100-fold increase in capacitance. Some MoO3/nanotube composites displayed capacitances as high as 540 F/g at 0.1 mV/s. This is the first example of solvent exfoliation of a layered metal oxide.We believe this work opens the way to liquid exfoliation of a wide range of layered compounds leading to an array of new solution processed 2D materials.

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Section: Introductionmentioning

confidence: 99%

Production of Molybdenum Trioxide Nanosheets by Liquid Exfoliation and Their Application in High-Performance Supercapacitors

et al. 2014

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“…An alternative solution is a top-down method of liquid phase exfoliation 18,19 , in which a bulk powder is sonicated or sheared in an appropriately chosen solvent, which also prevents the monoor few-layer nanosheets from reaggregation. This versatile and inexpensive technique allows to obtain large quantities of monolayer material [20][21][22][23][24][25] , which can be then used for ink-jet printing 26 , spray coating, forming hybrids and composites 27 , depositing thin films 28 , and functionalization 29 .…”

Section: Introductionmentioning

confidence: 99%

Revealing the nature of excitons in liquid exfoliated monolayer tungsten disulphide

et al. 2016

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Transition metal dichalcogenides hold promise for applications in novel optoelectronic devices. There is therefore a need for materials that can be obtained in large quantities and with well understood optical properties. In this report, we present a thorough photoluminescence (PL) investigations of monolayer tungsten disulphide obtained via liquid phase exfoliation. As shown by microscopy studies, the exfoliated nanosheets have dimensions of tens of nanometers and thickness of 2.5 monolayers on average. The monolayer content is about 20%. Our studies show that at low temperature the photoluminescence is dominated by excitons localized on nanosheet edges. As a consequence, the PL is strongly sensitive to environment and exhibits an enhanced splitting in magnetic field. As the temperature is increased, the excitons are thermally excited out of the defect states and the dominant transition is that of the negatively charged exciton. Furthermore, upon excitation with a circularly polarized light, the PL retains a degree of polarization reaching 50% and inherited from the valley polarized photoexcited excitons. The studies of PL dynamics reveal that the PL lifetime is on the order of 10 ps, probably limited by non-radiative processes. Our results underline the potential of liquid exfoliated TMD monolayers in large scale optoelectronic devices.

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“…By analogy to CNTs, graphene should have surface energy close to that of Imi-ILs which would be promising solvents for the exfoliation of graphite into graphene [81,98]. Luo et al [99] first presented a one-step electrochemical approach for the exfoliation of anode graphite rod to graphene sheets with the aid of Imi-ILs and water.…”

Section: Graphene Sheets In Imidazolium Ionic Liquidsmentioning

confidence: 99%

Progress in Imidazolium Ionic Liquids Assisted Fabrication of Carbon Nanotube and Graphene Polymer Composites

et al. 2013

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Carbon nanotubes (CNTs) and graphene sheets are the most promising fillers for polymer nanocomposites due to their superior mechanical, electrical, thermal optical and gas barrier properties, as well as high flame-retardant efficiency. The critical challenge, however, is how to uniformly disperse them into the polymer matrix to achieve a strong interface for good load transfer between the two. This problem is not new but more acute in CNTs and graphene, both because they are intrinsically insoluble and tend to aggregate into bundles and because their surfaces are atomically smooth. Over the past decade, imidazolium ionic liquids (Imi-ILs) have played a multifunctional role (e.g., as solvents, dispersants, stabilizers, compatibilizers, modifiers and additives) in the fabrication of polymer composites containing CNTs or graphene. In this review, we first summarize the liquid-phase exfoliation, stabilization, dispersion of CNTs and graphene in Imi-ILs, as well as the chemical and/or thermal reduction of graphene oxide to graphene with the aid of Imi-ILs. We then present a full survey of the literature on the Imi-ILs assisted fabrication of CNTs and graphene-based nanocomposites with a variety of polymers, including fluoropolymers, hydrocarbon polymers, polyacrylates, cellulose and polymeric ionic liquids. Finally, we give a future outlook in hopes of facilitating progress in this emerging area. OPEN ACCESSPolymers 2013, 5 848

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Liquid-phase exfoliation, functionalization and applications of graphene

Cited by 261 publications

References 114 publications

Production of Molybdenum Trioxide Nanosheets by Liquid Exfoliation and Their Application in High-Performance Supercapacitors

Production of Molybdenum Trioxide Nanosheets by Liquid Exfoliation and Their Application in High-Performance Supercapacitors

Revealing the nature of excitons in liquid exfoliated monolayer tungsten disulphide

Progress in Imidazolium Ionic Liquids Assisted Fabrication of Carbon Nanotube and Graphene Polymer Composites

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