Liquid‐Phase Exfoliation of Graphite Towards Solubilized Graphenes

Bourlinos, Athanasios B.; Georgakilas, Vasilios; Zbořil, Radek; Steriotis, Theodore; Stubos, A.K.

doi:10.1002/smll.200900242

Cited by 507 publications

(317 citation statements)

References 37 publications

(28 reference statements)

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“…This method is extremely versatile and can be used to produce a range of nanosheet types including graphene, 36,37 MoS2, 38-40 GaS 41 and black phosphorous. 42,43 Transmission electron microscopy (TEM) showed the dispersions to contain large numbers of electron transparent, and so relatively thin, nanosheets ( Figure 1A, inset).…”

Section: Mos2-only Anodesmentioning

confidence: 99%

Electrical, Mechanical, and Capacity Percolation Leads to High-Performance MoS₂/Nanotube Composite Lithium Ion Battery Electrodes

et al. 2016

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Advances in lithium ion batteries would facilitate technological developments inareas from electrical vehicles to mobile communications. While 2-dimensional systems like MoS2 are promising electrode materials due to their potentially high capacity, their poor ratecapability and low cycle-stability are severe handicaps. Here we study the electrical, mechanical and lithium storage properties of solution-processed MoS2/carbon nanotube anodes.Nanotube addition gives up to ×10 10 and ×40 increases in electrical conductivity and mechanical toughness respectively. The increased conductivity results in up to a ×100 capacity enhancement to ~1200 mAh/g (~3000 mAh/cm 3 ) at 0.1 A/g, while the improved toughness significantly boosts cycle stability. Composites with 20 wt% nanotubes combined high reversible capacity with excellent cycling stability (e.g. ~950 mAh/g after 500 cycles at 2 A/g) and high-rate capability (~600 mAh/g at 20 A/g). The conductivity, toughness and capacity scaled with nanotube content according to percolation theory while the stability increased sharply at the mechanical percolation threshold. We believe the improvements in conductivity and toughness obtained after addition of nanotubes can be transferred to other electrode materials such as silicon nanoparticles.Keywords: percolating, network, anode, mechanical 2 In recent years, lithium ion batteries (LIBs) have become the most common rechargeable power sources for portable electronic devices and electric vehicles. 1, 2 Nevertheless, they still suffer from several problems; their energy and especially power densities have not fulfilled their ultimate potential while their safety record is not unblemished. 3 A significant problem is that graphite, the dominant anode material used in LIBs, is limited by a relatively low theoretical capacity of 372 mAh/g. 4 As such, the development of the next-generation of LIBs, is expected to see the replacement of graphite-based anodes with alternative materials having higher capacity at similarly low cost. While a range of materials, including silicon, have been envisaged as future LIB anode materials, 4 of particular interest are 2-dimensional (2D) nanomaterials 5 such as graphene 6 and MoS2. 7 Over the last decade, 2D nano-materials have generated much excitement in the nanomaterials science community. [8][9][10] They come in many types including graphene, transition metal dichalcogenides (TMDs) and transition metal oxides (TMOs). These materials consist of covalently bonded monolayers which can stack via van der Waals interactions to form layered crystals. 8,9 Such 2D nanomaterials are often found as nanosheets with lateral size ranging from 10s of nm to microns and thickness of ~nm. 9 These materials have shown potential for applications 5 in both energy generation 11 and storage. 12 In the context of LIBs, exfoliated TMDs have received significant attention as prospective anode materials. 13,14 While bulk MoS2 was proposed 15 as a Li ion battery electrode material as early as 1980 due to its hi...

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Section: Mos2-only Anodesmentioning

confidence: 99%

Electrical, Mechanical, and Capacity Percolation Leads to High-Performance MoS₂/Nanotube Composite Lithium Ion Battery Electrodes

et al. 2016

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“…This results in the production of nanosheets which are stabilised against aggregation via the interaction with the liquid. 12,15,17,18 This method has been used to successfully produce dispersions of nanosheets of a range of materials, including graphene, 8,19 BN,6,20 and various transition metal dichalcogenides 6,10,21,22 such as MoS2 and WSe2. Using sonication-assisted exfoliation, dispersions of volumes typically in the range of hundreds of millilitres can be produced.…”

Section: Introductionmentioning

confidence: 99%

Large-Scale Production of Size-Controlled MoS₂ Nanosheets by Shear Exfoliation

Varrla¹,

Backes²,

et al. 2015

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In order to fulfil their potential for applications, it will be necessary to develop large-scale production methods for two-dimensional (2D) inorganic nanosheets. Here we demonstrate the large-scale shear-exfoliation of molybdenum disulphide nanosheets in aqueous surfactant solution using a kitchen blender. Using standard procedures, we measure how the MoS2 concentration and production rate scale with processing parameters. However, we also use recently developed methods based on optical spectroscopy to simultaneously measure both nanosheet lateral size and thickness, allowing us to also study the dependence of nanosheet dimensions on processing parameters. We found the nanosheet concentration and production rates to depend sensitively on the mixing parameters (the MoS2 concentration, Ci; the mixing time, t; the liquid volume, V; and the rotor speed, N). By optimising mixing parameters, we achieved concentrations and production rates as high as 0.4 mg/ml and 1.3 mg/min respectively. Conversely, the nanosheet size and thickness were largely invariant with these parameters. The nanosheet concentration is also extremely sensitive to the surfactant concentration. However, more interestingly the nanosheet lateral size and thickness also varied strongly with the surfactant concentration. This allows the mean nanosheet dimensions to be controlled during shear exfoliation at least in the range ~40-220 nm for length and ~2-12 layers for thickness. We demonstrate the importance of this by showing that the MoS2 nanosheets prepared using different surfactant concentrations, and so displaying different nanosheets sizes, perform differently when used as hydrogen evolution catalysts. We find the nanosheets produced using high surfactant concentrations, which gives smaller flake sizes, perform significantly better, consistent with catalysis occurring at nanosheet edges. Finally, we also demonstrate that shear exfoliation using a kitchen blender is not limited to MoS2 but can also be achieved for boron nitride and tungsten disulphide. ToC fig3

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“…While this was initially achieved by micromechanical cleavage, it soon became apparent that the sort of strategies used to exfoliate nanotubes in the liquid phase could be successfully applied to graphene. [41][42][43][44] In this paper we review the work carried out in our group on the liquid phase dispersion of nanotubes and graphene. We first consider the mechanisms for stabilisation of nanotubes (which also apply to graphene).…”

Section: Introductionmentioning

confidence: 99%

Liquid‐Phase Exfoliation of Nanotubes and Graphene

Coleman

2009

Adv Funct Materials

586

525

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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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Liquid‐Phase Exfoliation of Graphite Towards Solubilized Graphenes

Abstract: Colloidal graphene: Treatment of graphite powder with a series of certain aromatic solvents under sonication leads to the homologous set of colloidal dispersions containing solubilized graphenes (see image).

Cited by 507 publications

References 37 publications

Electrical, Mechanical, and Capacity Percolation Leads to High-Performance MoS₂/Nanotube Composite Lithium Ion Battery Electrodes

Electrical, Mechanical, and Capacity Percolation Leads to High-Performance MoS₂/Nanotube Composite Lithium Ion Battery Electrodes

Large-Scale Production of Size-Controlled MoS₂ Nanosheets by Shear Exfoliation

Liquid‐Phase Exfoliation of Nanotubes and Graphene

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Liquid‐Phase Exfoliation of Graphite Towards Solubilized Graphenes

Abstract: Colloidal graphene: Treatment of graphite powder with a series of certain aromatic solvents under sonication leads to the homologous set of colloidal dispersions containing solubilized graphenes (see image).

Cited by 507 publications

References 37 publications

Electrical, Mechanical, and Capacity Percolation Leads to High-Performance MoS2/Nanotube Composite Lithium Ion Battery Electrodes

Electrical, Mechanical, and Capacity Percolation Leads to High-Performance MoS2/Nanotube Composite Lithium Ion Battery Electrodes

Large-Scale Production of Size-Controlled MoS2 Nanosheets by Shear Exfoliation

Liquid‐Phase Exfoliation of Nanotubes and Graphene

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Electrical, Mechanical, and Capacity Percolation Leads to High-Performance MoS₂/Nanotube Composite Lithium Ion Battery Electrodes

Electrical, Mechanical, and Capacity Percolation Leads to High-Performance MoS₂/Nanotube Composite Lithium Ion Battery Electrodes

Large-Scale Production of Size-Controlled MoS₂ Nanosheets by Shear Exfoliation