Turbulence-assisted shear exfoliation of graphene using household detergent and a kitchen blender

Abstract

To facilitate progression from the lab to commercial applications, it will be necessary to develop simple, scalable methods to produce high quality graphene. Here we demonstrate the production of large quantities of defect-free graphene using a kitchen blender and household detergent. We have characterised the scaling of both graphene concentration and production rate with the mixing parameters: mixing time, initial graphite concentration, rotor speed and liquid volume. We find the production rate to be invariant with mixing time and to increase strongly with mixing volume, results which are important for scale-up. Even in this simple system, concentrations of up to 1 mg ml À1 and graphene masses of >500 mg can be achieved after a few hours mixing. The maximum production rate was $0.15 g h À1 , much higher than for standard sonication-based exfoliation methods. We demonstrate that graphene production occurs because the mean turbulent shear rate in the blender exceeds the critical shear rate for exfoliation.Over the last decade, graphene has become one of the most studied of all nano-materials due to its 2-dimensional structure and its unique set of physical properties. 1,2 During this period, the focus of much of the research community has been on mapping out and understanding the fundamental physics and chemistry of graphene. However, in recent years, the emphasis has started to shi slightly towards the demonstration of applications. 3 Over the next few years, we expect the emphasis to shi further as both academic and industrial researchers concentrate on fullling the applications potential of graphene, eventually leading to a range of graphene-enabled products.However, before this can be achieved, it will be critically important to develop industrially scalable production methods for graphene. While graphene can be produced by a range of techniques, many applications will require solution-processed 4 graphene. In particular, a number of applications will require access to large volumes of graphene dispersions or inks. Using standard solution deposition techniques such as inkjet printing 5,6 or spray coating, 7,8 such inks can be used to prepare a range of lms, coatings or patterned structures. In particular, applications in areas such as printed electronics will require the production of conductive lms or traces. Here, defect free graphene performs particularly well, giving high conductivity structures without high temperature post treatments. 5 Thus, it is clear that large scale production techniques for defect-free graphene are urgently required.Defect free graphene is generally produced by sonicating graphite powder either in certain solvents 9-16 or aqueous surfactant 17-23 solutions. The sonication tends to break up the graphite crystallites as well as exfoliating them to give large number of graphene nanosheets. 11 Raman spectroscopy 15,24,25 shows this method to produce negligible quantities of basal plane defects while XPS shows the akes to be un-oxidised. 14 While the graphene produced by this m...

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

“…It is important to do this first as nanosheet dispersions can be very sensitive to surfactant content, perhaps more so than any other parameter. 37 To do this, figure 3A). We note that this behaviour is distinct to that observed for graphene produced by shear-exfoliation in a slightly different blender with a different surfactant, where we found the graphene concentration to depend on the ratio of Csurf /Ci rather than Csurf alone.…”

“…Below, we will use this to measure the MoS2 concentration as a function of mixing parameters, in a manner similar to that recently reported for shear-exfoliated graphene. 35,37 However, in addition to concentration information, it has recently been shown that the extinction spectrum of MoS2 nanosheets carries information about both the mean nanosheet length and thickness. 39 The length effects are due to the effect of nanosheet edges on the spectral profile while quantum confinement effects result in well-defined shifts in A-exciton position with nanosheet thickness.…”

“…37,38 This gives graphene nanosheets of similar size and quality to those produced using sonication. The advantage of this technique is that much higher volumes can be produced compared to sonication and so much higher production rates can be achieved.…”

Facile and size-controllable preparation of graphene oxide nanosheets using high shear method and ultrasonic method

“…Recently, shear mixer was introduced to exfoliate the graphite into individual graphene nanosheets [3,4,[38][39][40]. Because the oxygen-containing groups binding on carbon atoms will increase the interlayer spacing of graphite oxide, and make the layered graphite oxide easier to cleave [10,41].…”

“…Recently, there has been growing interest in exfoliation of layered materials to produce two-dimensional (2D) nanosheets, such as graphene [2][3][4][5][6], graphene oxide (GO) [1,[7][8][9][10], etc. GO has recently attracted substantial interest as a possible intermediate for the preparation of graphene [11][12][13] and metal oxide/graphene nanocomposites [14][15][16].…”