Preparation of high concentration graphene dispersion with. Furthermore, graphene was produced by using supercritical. Production of high concentration graphene dispersions in. 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. Fewlayer graphene obtained by electrochemical exfoliation of graphite cathode ming zhoua, jie tangb, qian chengb, gaojie xua, ping cuia, luchang qina,c. In the case of odcb, the most effective exfoliation. 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. Abstract a method is demonstrated to prepare graphene dispersions at high concentrations, up to 1. Highquality thin graphene films from fast electrochemical.
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. Highconcentration aqueous dispersions of graphene produced. 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. 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. This gives dispersions of graphene at concentrations of up to 1. Journal of colloid and interface science 2017, 497, 359367. In this paper, an effort has been made to demonstrate the preparation of homogeneous and stable dispersion of graphene in odcb solvent. In this paper, by dispersing graphene powder at low boiling point solvent water.
University of groningen dispersion of graphene in ethanol. Effect of sonication time on the yield and quality of graphene exfoliated in dmf has been studied. Boilingpoint organic solvents by liquidphase noncovalent. Graphite was exfoliated to graphene by tip sonic using sodium cholate as a surfactant in the presence of millipore water as a medium. 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. Efficient exfoliation of graphite in solutions to obtain high quality graphene flakes is desirable for printable electronics, catalysis, energy storage, and composites.
This does not require high vacuum and high temperatures as well as the low cost of the starting materials. This work builds upon over 50 years of study into chemical exfoliation of graphite24. The discovery of graphene in 2004 gave us a new lowdimensional carbonbased nanomaterial to explore 2, 3. A method is presented to produce graphene dispersions, stabilized in water by the surfactant sodium cholate, at concentrations up to 0. Electrochemical exfoliation of graphite in quaternary. Concentration solvent exfoliation of graphene high. Request pdf highconcentration solvent exfoliation of graphene a method is demonstrated to prepare graphene dispersions at high. 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. Background history graphene is a flat sheet of carbon just one atom thick. From equation1, we expect a minimal energy cost of exfoliation for solvents whose surface energy matches that of graphene. Since graphene has a highly conjugated system, it is easy to conduct strong interaction with conjugated structure. Mechanical exfoliation to make graphene and visualization. To confirm the presence of few layer graphene, its dispersion, which exhibits tyndall effect, was characterized by rama chemically modified graphenes.
For each sample the visual aspect 45 of the dispersion is shown. Graphite can be highly exfoliated in the solvent n. A high graphene dispersion concentration can be obtained by selecting a suitable solvent that includes organic solvents, 6,11121415 16 17181920 organosilanes, 21 ionic. Effect of processing parameters on graphene concentration. Surfactant mediated liquid phase exfoliation of graphene. To exploit the remarkable properties of graphene fully, an efficient largescale production method is required. Liquidphase exfoliation of graphite to produce highquality. 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. Exfoliation of graphite into graphene in aqueous solutions of. Synthesis of few layer graphene by direct exfoliation of. The graphite was dispersed in the relevant solvent cylindrical vial, 1025 ml solvent at a concentration of 0. Influence of ternary hydroalcoholic solvent on direct. 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. The electrical conductivities of the graphene were up to 849 scm.
Characterization after mechanical exfoliation charlotte reeves research advisor. In fact, the fully exfoliated top phase can trap a larger amount of liquid during the reaggregation process compared to unexfoliated bottom phase. Request pdf highconcentration solvent exfoliation of graphene a method is demonstrated to prepare graphene dispersions at high concentrations, up to 1. Liquidphase exfoliation, the use of a sheared liquid to delaminate graphite into fewlayer graphene, is a promising technique for the largescale production of graphene. The exfoliation of graphene in liquids by electrochemical. Exfoliation in these electrolytes leads to graphene with a high yield 85%. Because of the complexity of this method, it is not possible to really get information on the role of py1so. Solventexfoliated graphene at extremely high concentration. Graphene sheets may be precipitated by centrifuging a graphene solution for more than 3 h at 17,000 rpm. Prethermal activation of pristine graphite in a sealed bath is a crucial factor. Graphene synthesis via exfoliation of graphite by ultrasonication. Effect of concentration of surfactant on the exfoliation. This approach is achieved by exfoliating graphite in an ethanolwater mixture and. Exfoliation of highquality graphene in volatile and.
Liquidphase exfoliation of graphene semantic scholar. High concentration graphene dispersion stabilized by block copolymers in ethanol. In summary, we propose a simple yet general route to prepare highconcentration surfactantfree graphene liquid dispersions based on a distillationassisted solvent exchange technique. Preparation of ultra high concentration graphene in water. 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. However, production and dispersion of unfunctionalized graphene are still big challenges. Metal dichalcogenides and their application as supercapacitors, angewandte chemie, 126, 46, 1278412788, 2014. A simple route towards highconcentration surfactantfree. Aug 10, 2008 here, we demonstrate graphene dispersions with concentrations up to. May 15, 2014 the concentration of this solution portion was measured and was 5. Modelling the exfoliation of graphite for production of graphene. In this paper we report liquidphase exfoliation to produce graphene from tetraethylammonium graphite intercalation compound teagic. Scalable production of large quantities of defect free. Solvothermalassisted liquidphase exfoliation of graphite in.
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. Strong bonds link each carbon atom to three other carbon atoms and form hexagonal sixsided shapes. Highconcentration solvent exfoliation of graphene request pdf. Electrochemical exfoliation of graphite in quaternary ammoniumbased deep eutectic solvents. Production of graphene by exfoliation of graphite in a. High yield production and purification of few layer graphene by gum arabic assisted physical sonication. The use of water as a solvent for exfoliation purposes is very important due to its environ. Liquid dispersions of zeolite monolayers with high. From the plot, it is clear that the wavenumber shift between the two different substrates is in the range of. These different methods are used to achieve high yield of graphene for different application. Concentration solvent exfoliation of graphene khan.
Effect of concentration of surfactant on the exfoliation of graphite to graphene in aqueous media regular paper. 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. Herein, we demonstrate a simple method for preparation and dispersion of such graphene with low cost and non toxicum. Stable high concentration aqueous dispersions 1 mg ml. Fewlayer graphene obtained by electrochemical exfoliation of. Production of highconcentration graphene dispersions in low. 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.
Concentration solvent exfoliation of graphene khan, umar. The dispersions can be further concentrated to reach the graphene concentration as high as 3. Although extremely high concentration of graphene in nmp has already been reported by our group, i. So, exfoliation using odcb solvent has been chosen. 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. Highyield production of graphene by liquidphase exfoliation. Highconcentration shearexfoliated colloidal dispersion. This process relies on lowpower sonication for long times, up to 460 hours. The production of concentrated dispersions of fewlayer. It is possible to achieve concentrations of up to 0. Scalable preparation of lowdefect graphene by urea. Here we show that high quality monolayer graphene can be produced at signi. A method is demonstrated to prepare graphene dispersions at high concentrations, up to 1.
A welldispersed, defectfree, and nonoxidized graphene solution was obtained. Surfactantfree exfoliation of graphite in aqueous solutions. Producing processable graphene flakes in large quantities remains an ongoing challenge for largescale applications. Even moreso than with nanotubes, the success of graphene research depends on the exfoliation of graphene from its parent crystal. 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. To explore a new equipment to offer high shear, shen et al. 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. 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. Casiraghi a,d, a school of chemistry and photon science institute, oxford road, university of manchester, manchester. Spontaneous highconcentration dispersions and liquid. A simple method for graphene production based on exfoliation of graphite in water using 1pyrenesulfonic acid sodium salt h. High yield and high concentration fewlayer graphene.
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. Highconcentration, spontaneous dispersions and liquid. High concentration solvent exfoliation of graphene. Highconcentration solutions, both isotropic and liquid crystalline, could be particularly useful for making. 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. 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. Graphene sheets resemble a honeycomb or chicken wire. High yield production and purification of few layer. In the exfoliation process, hbpe adsorbs onto the surface of exfoliated graphene flakes. Enhancing the liquidphase exfoliation of graphene in organic. 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. High concentration fewlayer graphene sheets obtained by.
The journal of physical chemistry c 20, 117 20, 1073010742. Graphene can be dispersed at concentrations of up to 0. Many promising macroscopic applications of graphene require the development of new routes for effective graphite exfoliation and processing1,7. This process relies on lowpower sonication for long times, up to 460 h. The dispersed concentration increases with sonication time while the best quality dispersions are obtained for centrifugation. High concentration solutions, both isotropic and liquid crystalline, could be particularly useful for making. Production of highconcentration graphene dispersions in. Biodegradable and widely available from renewable sources, cnc have proven to be very efficient graphene stabilizers even at low concentrations 0. Concentration solvent exfoliation of graphene khan 2010. A simple method for graphene production based on exfoliation. Graphene dispersion and exfoliation in low boiling point. Liquidphase exfoliation of graphite to produce high. Graphene dispersion and exfoliation in low boiling point solvents.
The process uses low power sonication for long times up to 400 h followed by centrifugation to yield stable dispersions. This gives dispersions of graphene at concentrations of. The different exfoliation routes of graphite to produce graphene by sonication in solvent, chemical oxidation and electrochemical oxidation are compared. Graphene has attracted much attention as a new nanocarbon for its unique structure and properties. 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. Our results are consistent with earlier analysis of graphene dispersions in nmp. Highconcentration, spontaneous dispersions and liquid crystals of graphene natnael behabtu, jay r. Xray diffraction and scanning electron microscopy sem results implied that the interlayer. The concentration of the graphene product at various volume ratios of toluene to oleylamine is shown in figure 4. However, the microscale and nanoscale fluidstructure processes controlling the exfoliation are not fully understood. Thus, liquid exfoliation of graphene will become a critically important technology in the near future.
Jun 14, 2017 high quality fewlayer to multilayer graphene sheets were exfoliated in n,ndimethylformamide dmf and 1propanol by simple liquidphase exfoliation method. This fundamentally expected behavior can be used to deposit monolayers on supports or to reassemble into hierarchical materials to produce, by. 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. 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.
A series of stable graphene dispersions in different organic solvents were prepared by the liquidphase exfoliation of microcrystalline graphite. Low defect concentration fewlayer graphene using a two. Liquid exfoliation of multilayer graphene in sheared. Enhancing liquidphase exfoliation of graphene with addition of anthracene in organic solvents. The pristine graphite was heattreated in nmethyl2pyrrolidone before it was exfoliated in solvents containing 0.
Effect of thermal treatment on production of graphene from. On the other hand, liquidphase shear exfoliation with a highshear mixer is easily. 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. 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. 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. Highquality graphene via microwave reduction of solution. High yield and high concentration fewlayer graphene sheets.
Concentration solvent exfoliation of graphene, small. The effect of surfactants and their concentrations on the. The intercalation of nontoxic tea was achieved by simple high power tipsonication of graphite in tea aqueous solution. The first successful lpe of graphite was achieved in the organic solvent nmp. Pdf highconcentration solvent exfoliation of graphene. Exfoliation and dispersion of graphene in ethanolwater. It can be seen from figure 4 that the concentration of graphene reaches the highest value of 0.
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