Exfoliation of graphite into graphene in aqueous solutions of. The production of graphene in the liquid phase exfoliation is a cost efficient method one part of this work is devoted to learn the method of production of. In this study, using the strategy of tailoring hansen solubility parameters hsp, a method based on exfoliation of graphite in wateracetone mixtures is demonstrated to achieve concentrated graphene. In particular, the solvent composition that led to high graphene concentrations were located in the center of the limiting boundary region, and the highest graphene concentration obtained was 29.
Highquality thin graphene films from fast electrochemical. Surfactantfree exfoliation of graphite in aqueous solutions. Highconcentration, spontaneous dispersions and liquid. The graphite was dispersed in the relevant solvent cylindrical vial, 1025 ml solvent at a concentration of 0.
Liquidphase exfoliation of graphene semantic scholar. Xray diffraction and scanning electron microscopy sem results implied that the interlayer. To confirm the presence of few layer graphene, its dispersion, which exhibits tyndall effect, was characterized by rama chemically modified graphenes. Here we report a prompt electrochemical exfoliation of graphene sheets into aqueous solutions of different inorganic salts nh 4 2 so 4, na 2 so 4, k 2 so 4, etc. Aug 10, 2008 here, we demonstrate graphene dispersions with concentrations up to. Graphite was exfoliated to graphene by tip sonic using sodium cholate as a surfactant in the presence of millipore water as a medium.
Production of high concentration graphene dispersions in lowboilingpoint organic solvents by liquidphase noncovalent exfoliation of graphite with a hyperbranched polyethylene and formation of graphene ethylene copolymer composites. The dispersions can be further concentrated to reach the graphene concentration as high as 3. Liquidphase exfoliation, the use of a sheared liquid to delaminate graphite into fewlayer graphene, is a promising technique for the largescale production of graphene. Production of high concentration graphene dispersions in. The exfoliation of graphene in liquids by electrochemical. The use of water as a solvent for exfoliation purposes is very important due to its environmentally friendly nature and almost no cost, contrary to organic media. Electrochemical exfoliation of graphite in quaternary. Since graphene has a highly conjugated system, it is easy to conduct strong interaction with conjugated structure. Journal of colloid and interface science 2017, 497, 359367.
Graphene dispersion and exfoliation in low boiling point. For example, coleman and coworkers demonstrated the exfoliation of graphene at relatively high concentration in low boiling point solvents such as chloroform and isopropanol 20arlene et al. This approach is achieved by exfoliating graphite in an ethanolwater mixture and. Boilingpoint organic solvents by liquidphase noncovalent. Surfactant mediated liquid phase exfoliation of graphene. Scalable production of large quantities of defect free. Fewlayer graphene obtained by electrochemical exfoliation of graphite cathode ming zhoua, jie tangb, qian chengb, gaojie xua, ping cuia, luchang qina,c. Graphene synthesis via exfoliation of graphite by ultrasonication. High yield and high concentration fewlayer graphene. In the present work, the use of a commercial ionic liquid as a convenient solvent medium for graphite exfoliation in mild and easy conditions without any chemical modification is presented. A welldispersed, defectfree, and nonoxidized graphene solution was obtained. Biodegradable and widely available from renewable sources, cnc have proven to be very efficient graphene stabilizers even at low concentrations 0. Read high yield graphene exfoliation using sodium dodecyl sulfate accompanied by alcohols as surfacetensionreducing agents in aqueous solution, carbon on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. The use of water as a solvent for exfoliation purposes is very important due to its environ.
This gives dispersions of graphene at concentrations of up to 1. In this paper we report liquidphase exfoliation to produce graphene from tetraethylammonium graphite intercalation compound teagic. Effect of processing parameters on graphene concentration. The discovery of graphene in 2004 gave us a new lowdimensional carbonbased nanomaterial to explore 2, 3. From the plot, it is clear that the wavenumber shift between the two different substrates is in the range of. Nov 17, 2015 in particular, the most effective exfoliation was obtained with 15 volume % of notbz in nmp as a solvent, with a concentration of exfoliated graphene of 250. A method is demonstrated to prepare graphene dispersions at high concentrations, up to 1. Request pdf highconcentration solvent exfoliation of graphene a method is demonstrated to prepare graphene dispersions at high concentrations, up to 1. High yield production and purification of few layer graphene by gum arabic assisted physical sonication. Pdf highconcentration solvent exfoliation of graphene.
Graphene can be dispersed at concentrations of up to 0. Strong bonds link each carbon atom to three other carbon atoms and form hexagonal sixsided shapes. The dispersed concentration increases with sonication time while the best quality dispersions are obtained for centrifugation. A high graphene dispersion concentration can be obtained by selecting a suitable solvent that includes organic solvents, 6,11121415 16 17181920 organosilanes, 21 ionic. Concentration solvent exfoliation of graphene khan, umar. Background history graphene is a flat sheet of carbon just one atom thick. The pristine graphite was heattreated in nmethyl2pyrrolidone before it was exfoliated in solvents containing 0. Effect of sonication time on the yield and quality of graphene exfoliated in dmf has been studied.
Effect of concentration of surfactant on the exfoliation of graphite to graphene in aqueous media regular paper. The most effective approach to practical exploitation of the layered solids that often have unique valuable propertiessuch as graphene, clays, and other compoundsis by dispersion into colloidal suspensions of monolayers, called liquid exfoliation. Spontaneous highconcentration dispersions and liquid. Furthermore, graphene was produced by using supercritical. This gives dispersions of graphene at concentrations of. Graphene sheets may be precipitated by centrifuging a graphene solution for more than 3 h at 17,000 rpm. To exploit the remarkable properties of graphene fully, an efficient largescale production method is required. This work builds upon over 50 years of study into chemical exfoliation of graphite24.
High concentration fewlayer graphene sheets obtained by. Concentration solvent exfoliation of graphene khan. Scalable preparation of lowdefect graphene by urea. Highconcentration aqueous dispersions of graphene produced.
Metal dichalcogenides and their application as supercapacitors, angewandte chemie, 126, 46, 1278412788, 2014. Effect of thermal treatment on production of graphene from. It can be seen from figure 4 that the concentration of graphene reaches the highest value of 0. Jun 14, 2017 high quality fewlayer to multilayer graphene sheets were exfoliated in n,ndimethylformamide dmf and 1propanol by simple liquidphase exfoliation method. This process relies on lowpower sonication for long times, up to 460 hours.
May 15, 2014 the concentration of this solution portion was measured and was 5. Care must be taken as excessive sonication can lead to destruction of the graphene. Liquid dispersions of zeolite monolayers with high. Our results are consistent with earlier analysis of graphene dispersions in nmp. Exploring the graphene material is premised on the graphene sheets being singlelayer graphene sg or bilayer graphene bg state, and graphene suspension keeps stably disperse are critical. Concentration solvent exfoliation of graphene high. Chemical exfoliation methods based on the hummers method, oxidation of graphite into thin graphene oxide go, followed by chemical or thermal reduction, haverecentlydrawn much attentiondueto the advantages of potentially lowcost and solutionprocessed fabrication. So, exfoliation using odcb solvent has been chosen. Concentration solvent exfoliation of graphene khan 2010. High concentration fewlayer graphene sheets obtained by liquid phase exfoliation of graphite in ionic liquid daniele nuvoli, a luca valentini, b valeria alzari, a sergio scognamillo, a silvia bittolo bon, b massimo piccinini, c javier illescas d and alberto mariani a.
Lukaszew april, 2010 abstract the purpose of this experiment was to produce and characterize samples of graphene, defined as a oneatom layer of hexagonally bonded carbon atoms, using a method of mechanical exfoliation. Effect of concentration of surfactant on the exfoliation. A simple route towards highconcentration surfactantfree. Highquality graphene via microwave reduction of solution. Liquidphase exfoliation of graphite to produce highquality. Efficient exfoliation of graphite in solutions to obtain high quality graphene flakes is desirable for printable electronics, catalysis, energy storage, and composites.
These different methods are used to achieve high yield of graphene for different application. Dec, 2012 by this technique, our research group obtained fewlayer graphene sheets by sonication of graphite with nmethyl pyrrolidone, isocyanates, nvinyl caprolactam, a commercial ionic liquid, and an acrylate, thus, achieving a graphene concentration as high as 2. Because of the complexity of this method, it is not possible to really get information on the role of py1so. Characterization after mechanical exfoliation charlotte reeves research advisor. Request pdf highconcentration solvent exfoliation of graphene a method is demonstrated to prepare graphene dispersions at high. However, production and dispersion of unfunctionalized graphene are still big challenges. Abstract a method is demonstrated to prepare graphene dispersions at high concentrations, up to 1.
Highconcentration shearexfoliated colloidal dispersion. Influence of ternary hydroalcoholic solvent on direct. High yield production and purification of few layer. For each sample the visual aspect 45 of the dispersion is shown. In this paper, an effort has been made to demonstrate the preparation of homogeneous and stable dispersion of graphene in odcb solvent. Gengzhi sun, juqing liu, xiao zhang, xuewan wang, hai li, yang yu, wei huang, hua zhang and peng chen, fabrication of ultralong hybrid microfibers from nanosheets of reduced graphene oxide and transition. High concentration graphene dispersion stabilized by block copolymers in ethanol. Highconcentration solutions, both isotropic and liquid crystalline, could be particularly useful for making. The effect of surfactants and their concentrations on the. Here we show that high quality monolayer graphene can be produced at signi.
It is possible to achieve concentrations of up to 0. University of groningen dispersion of graphene in ethanol. The merits of our approach lie in the quick and complete removal of the remaining solvent from the exfoliated graphitic sheets without the help of high temperature annealing or long vacuum drying. Modelling the exfoliation of graphite for production of graphene mehwish abro the aim of my thesis is to make a theoretical model of data obtained from liquidphase exfoliation of graphene. Production of graphene by exfoliation of graphite in a. In the exfoliation process, hbpe adsorbs onto the surface of exfoliated graphene flakes. A method is presented to produce graphene dispersions, stabilized in water by the surfactant sodium cholate, at concentrations up to 0. In fact, the fully exfoliated top phase can trap a larger amount of liquid during the reaggregation process compared to unexfoliated bottom phase. High concentration solutions, both isotropic and liquid crystalline, could be particularly useful for making. A rapidly increasing list of graphene production techniques have been developed to enable graphene s use in commercial applications isolated 2d crystals cannot be grown via chemical synthesis beyond small sizes even in principle, because the rapid growth of phonon density with increasing lateral size forces 2d crystallites to bend into the third dimension. Highconcentration solvent exfoliation of graphene request pdf. Liquid exfoliation of multilayer graphene in sheared.
To explore a new equipment to offer high shear, shen et al. Preparation of high concentration graphene dispersion with. Solventexfoliated graphene at extremely high concentration. Achieving concentrated graphene dispersions in water. Modelling the exfoliation of graphite for production of graphene. Highyield production of graphene by liquidphase exfoliation. One of the problems with solvent exfoliation of graphene is that the best solvents tend to have high boiling points and so are difficult to remove and can present problems for flake deposition and composite formation. Graphite can be highly exfoliated in the solvent n. A series of stable graphene dispersions in different organic solvents were prepared by the liquidphase exfoliation of microcrystalline graphite. The production of concentrated dispersions of fewlayer. Producing processable graphene flakes in large quantities remains an ongoing challenge for largescale applications. The results revealed that the graphene yield first increased with increasing initial graphite concentration and reached a maximum at an initial graphite concentration of approximately 14. Thus, liquid exfoliation of graphene will become a critically important technology in the near future. High concentration solvent exfoliation of graphene.
Casiraghi a,d, a school of chemistry and photon science institute, oxford road, university of manchester, manchester. Production of graphene by liquidphase exfoliation of. High yield and high concentration fewlayer graphene sheets. This does not require high vacuum and high temperatures as well as the low cost of the starting materials. In this paper, by dispersing graphene powder at low boiling point solvent water. The journal of physical chemistry c 20, 117 20, 1073010742. Exfoliation in these electrolytes leads to graphene with a high yield 85%. Electrochemical exfoliation of graphite in quaternary ammoniumbased deep eutectic solvents. Concentration solvent exfoliation of graphene, small. In the case of odcb, the most effective exfoliation.
Graphene sheets resemble a honeycomb or chicken wire. Herein, we demonstrate a simple method for preparation and dispersion of such graphene with low cost and non toxicum. Sonicationassisted liquidphase exfoliation of graphite, for example, has been extensively used for the production of fewlayer graphene sheets, but suffers from low efficiency and high energy consumption and thus is not viable for largescale production. Although extremely high concentration of graphene in nmp has already been reported by our group, i. Transmission electron microscopy shows the sonication to reduce the flake size, with flake dimensions scaling as t12. The graphene yield from the graphite was as high as 14% after 3 cycles of sonication and graphene collection. Liquidphase exfoliation of graphite to produce high.
Enhancing the liquidphase exfoliation of graphene in organic. Many promising macroscopic applications of graphene require the development of new routes for effective graphite exfoliation and processing1,7. Fewlayer graphene obtained by electrochemical exfoliation of. To that end, topdown colloidal approaches such as the exfoliation of powdered graphite in the liquid phase is a very promising route due to its simplicity, utilization of lowcost and readily available graphite, high throughput potential, possibility of. Graphite oxide with large lateral dimensions has an exfoliation yield of 100%, but it has not been possible to completely remove the oxygen functional groups so that the reduced form of graphene oxide go. Here, we demonstrate the exfoliation of graphene at relatively high concentration in low boiling point solvents such as chloroform and isopropanol. Production of highconcentration graphene dispersions in low.
Production of highconcentration graphene dispersions in. The first successful lpe of graphite was achieved in the organic solvent nmp. A simple method for graphene production based on exfoliation of graphite in water using 1pyrenesulfonic acid sodium salt h. Our experiments demonstrate that the prepared graphene dispersions contain fewlayer graphene flakes without severe defects. Low defect concentration fewlayer graphene using a two.
A simple method for graphene production based on exfoliation. Graphene has attracted much attention as a new nanocarbon for its unique structure and properties. Solvothermalassisted liquidphase exfoliation of graphite in. Enhancing liquidphase exfoliation of graphene with addition of anthracene in organic solvents.
Highconcentration, spontaneous dispersions and liquid crystals of graphene natnael behabtu, jay r. Prethermal activation of pristine graphite in a sealed bath is a crucial factor. This fundamentally expected behavior can be used to deposit monolayers on supports or to reassemble into hierarchical materials to produce, by. Exfoliation of highquality graphene in volatile and. Graphene dispersion and exfoliation in low boiling point solvents. Mechanical exfoliation to make graphene and visualization. The process uses low power sonication for long times up to 400 h followed by centrifugation to yield stable dispersions. We report in this paper the successful production of stable high concentration graphene dispersions in lowboilingpoint, lowpolarity conventional organic solvents chloroform and thf by liquidphase noncovalent exfoliation of graphite assisted with a hyperbranched polyethylene hbpe as the stabilizer. The different exfoliation routes of graphite to produce graphene by sonication in solvent, chemical oxidation and electrochemical oxidation are compared.
However, the microscale and nanoscale fluidstructure processes controlling the exfoliation are not fully understood. The electrical conductivities of the graphene were up to 849 scm. In particular, the most effective exfoliation was obtained with 15 volume % of notbz in nmp as a solvent, with a concentration of exfoliated graphene of 250. Synthesis of few layer graphene by direct exfoliation of. The concentration of the graphene product at various volume ratios of toluene to oleylamine is shown in figure 4. The intercalation of nontoxic tea was achieved by simple high power tipsonication of graphite in tea aqueous solution. Exfoliation and dispersion of graphene in ethanolwater. This process relies on lowpower sonication for long times, up to 460 h. Stable high concentration aqueous dispersions 1 mg ml. In summary, we propose a simple yet general route to prepare highconcentration surfactantfree graphene liquid dispersions based on a distillationassisted solvent exchange technique.
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