Obtaining stable aqueous dispersions of graphene based materials is a major obstacle in the development and widespread use of graphene in nanotechnology. Highefficiency exfoliation of largearea monolayer graphene oxide with controlled dimension. Deposition and characterisation of singlesheet graphene and. Introduction graphene, possessing excellent mechanical, electric, thermal conductivities and optical, biologic properties, has drawn. Novel preparation of hydrophilic graphenegraphene oxide. Our basic strategy involved the complete exfoliation of go into individual go sheets followed by their insitu reduction to produce individual graphene like sheets 19,20. These isocyanatetreated gos igos can then be exfoliated into functionalized graphene oxide nanoplatelets that can form a stable dispersion in polar aprotic solvents. Subsequently reduced graphene oxide rgo having few layer graphene is extracted from go by the thermal reduction of go.
Computational modeling of graphene oxide exfoliation and. Research article preparation and characterization of reduced. One step electrochemical exfoliation of natural graphite. Highefficiency exfoliation of largearea monolayer graphene. Preparation and characterization of reduced graphene oxide. Comparison between exfoliated graphite, graphene oxide and multiwalled carbon nanotubes as reinforcing agents of a polyurethane elastomer. Secondly, the bulk graphite oxide can be exfoliated by sonication to form colloidal suspensions of monolayer, bilayer or fewlayer go sheets in. A simple approach to stepwise synthesis of graphene oxide.
Rapid heating of graphite oxide and exfoliation yields highly dispersed carbon powder with a few percent of graphene flakes. Advances in microwaveassisted production of reduced graphene. Synthesis of highquality graphene with a predetermined number of. Variation of exfoliated graphene flake thickness and lateral diameters with increasing. Recently, graphene oxide go, which was prepared by chemically oxidizing graphite to graphite oxide gto with strong oxidants and ultrasonic cleavage, has attracted much attention as a possible intermediate for manufacture of graphene in large volume.
This approach is effective for exfoliation of graphite oxide and yields. Synthesis and characterization of exfoliated graphene oxide. Characterization after mechanical exfoliation charlotte reeves research advisor. Carbon exists in threedimensional 3d forms regarded as allotropes as diamond and graphite. As the graphene can be considered as the core structural motif of graphite, carbon nanotubes cnts, and many other carbon nanomaterials, it is possible to obtain graphene materials through the exfoliation of those by mechanical, chemical, thermal, or electrical routes. Synthesis of graphene materials by electrochemical. Andre geim and konstantin novoselov initially used adhesive tape to split graphite into graphene. Pdf synthesis and exfoliation of isocyanatetreated. Nowadays, graphene can be produced by micromechanical exfoliation of highly ordered pyrolytic graphite,20 epitaxial growth,17,23,24 and chemical vapor. We report a simple room temperature method for the exfoliation of. Modelling the exfoliation of graphite for production of graphene diva. In this thesis we demonstrate a highly efficient electrochemical exfoliation of graphite in organic solvent containing tetraalkylammonium salts, avoiding oxidation. The bulk graphite oxide can be viewed as an accumulation of go sheets and was synthesized by brodie in 1855 by adding a portion of potassium chlorate to graphite in fuming nitric acid.
Tractable synthesis of graphene oxide by electrochemical. Synthesis of graphenebased nanosheets via chemical. Characterization of igos by ftir spectroscopy and elemental analysis suggested that the isocyanate. Short communication optimization of production of graphene. Exfoliation experiments were conducted both for odcontaining graphene oxide and odstripped graphene oxide samples, basewashed go bwgo, in order to detect the effect of oxidative debris on agglomeration of graphene layers. Ultrasonic exfoliation and dispersion is an very efficient, rapid and costeffective method to synthesize, disperse and functionalize graphene oxide on industrial scale. Inthis procedure, graphene akes supported on sisio 2 substrate were. In a typical experiment, the go sample was taken in a graphite boat susceptor and placed inside a cvd inductionrolled quartz tube.
Nov 27, 2017 currently, graphene oxide go is one of the most widely studied materials synthesized by the solution processed chemical approach 9,11,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32. Ksv nima an 3 ho hooc cooh oh oh ho o oh oh cooh ho cooh cooh graphene is a form of carbon where the carbon atoms have formed a planar sheet. In general, these conventional methods are assisted with intercalation via covalent or noncovalent functionalization, expansion, and swelling, adsorption of organic molecules in gas. 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.
Reviewprogress of research on the preparation of graphene. The substantial electron conjugation in graphene results in fascinating electronic, thermal, magnetic, optical, mechanical, and chemical properties. Graphene oxide is watersoluble, amphiphilic, nontoxic, biodegradable and can be easily dispersed into stable colloids. Experts at manchester and sports footwear firm inov8 collaborate to create the worlds first running shoe with a graphene enhanced foam in the sole.
The ellipsometric characterisations also matches with that of the thermally reduced graphene oxide films formed. Computational modeling of graphene oxide exfoliation and lithium storage characteristics reza mortezaee wright state university follow this and additional works at. Chemical or thermal treatments are popular approaches to exfoliate graphite chunks. A diagram of the ego preparation method is shown in fig. The synthesis of graphene oxide via electrochemical. Particular emphasis is directed toward the synthesis of graphene oxide, as well as its structure.
The efficacy of atomistic simulations in obtaining a molecularlevel insight into aggregation and exfoliation of graphene graphene oxide go is hindered by length and time scale limitations. Current work investigates the onset temperature where reduction in terms of exfoliation takes place, which is determined to be 325 c at standard atmospheric pressure. Graphene foam doubles longevity of new running shoe. Exfoliation of graphite into graphene in aqueous solutions. Exfoliation of graphite into graphene in aqueous solutions of. Extensive characterizations showed that the asprepared materials consisted of crumpled, fewlayer thick and electronically conductive. Among several methodologies to improve the solution processing of graphene based materials, noncovalent functionalization has been considered as the simplest and nondestructive method. Since graphene was first reported in 2004, made using mechanical exfoliation from graphite, graphite oxide has attracted a great deal of interest, as researchers have explored simpler, more efficient, cheaper and better yielding methods of synthesizing graphene, which can be scaled up easily and retain commercially viable properties for. Manchester academics conferred as fellows of the academy of social sciences. We demonstrated that the graphite did not need to be oxidized to such a deep degree as described in hummers method because the space distance increased little when the oxidation proceeded to a certain extent and the obtained graphite oxides gtos could be fully exfoliated to single layers with high thermal stability. Since monolayer graphene was first successfully separated from threedimensional 3d natural graphite by topdown mechanical exfoliation, graphene with its unique physical and chemical properties has attracted great attention as an appealing platform for diverse applications in the fields of electronics, optoelectronics, and other fields 24. The effects of applied bias, electrolyte concentration and the duration of the electrochemical exfoliation on the quality of the go nanosheets were investigated. In the past, the electrochemical exfoliation of graphite has been.
Onestep synthesis and characterization of reduced graphene oxide using chemical exfoliation method highlights abstract graphical abstract keywords. Apr 08, 2021 graphene oxide go, an oxidative exfoliation product of graphite, has gained great interest as a precursor for building graphene based bulk engineering materials due to the high yield of single layers from their synthesis, the large lateral dimensions of the sheets, their excellent dispersibility in water, and the ease of conversion to reduced go rgo. Materials and methods graphite oxide was prepared from puri. Large scale preparation of singlelayer graphene and graphene oxide is of great importance due to their potential applications. This is in stark contrast to reduced graphene oxide rgo graphene, where the rgo process permanently damages the graphene lattice because of the chemical routes involved. Synthesis of electrochemical exfoliated graphene oxide. Hummers method is one of the most common methods used in synthesizing graphene oxide. Synthesis and exfoliation of isocyanatetreated graphene oxide nanoplatelets sasha stankovich a, richard d. Evidence of the 3d graphitic form of carbon dates as far back to 1500s 2. Synthesis of reduced graphene oxide using novel exfoliation. For instance, a liquid phase exfoliation could be demonstrated as a technique to produce high quality, oxide free and defectfree graphene sheets upon treatment with nmethyl2pyrrolidone nmp and a subsequent thermal treatment at. Highquality graphene via microwave reduction of solution.
Graphene oxide as a substrate for a variety of chemical transformations, including its reduction to graphene like materials, is also discussed. Introduction the field of nanotechnology has blossomed following several studies on carbon. The preparation of graphene oxide and its derivatives and their. Reduction graphene oxide chemical reduction of graphite oxide is one of the conventional procedures to prepare graphene in large quantities 84. The effects of applied bias, electrolyte concentration and the duration of the electrochemical exfoliation on the quality of the go nanosheets were. Pdf exfoliation of graphite into graphene in aqueous. Graphite oxide is then exfoliated into monolayers or fewlayered stacks of graphene oxide xgo. Graphite, graphene, reduced graphene oxide, nanosheets, oxidation, exfoliation.
Pdf covalent modification and exfoliation of graphene oxide. Reduced go rgo is obtained by the extensive reduction of go using different methods, yielding a significantly. In this study, electrochemical exfoliation method was adopted in the production of graphene oxide go. This method provides graphene with about 2 at% of chlorine. Electrochemical exfoliation schematic diagram 15 in electrochemical exfoliation, many researchers utilized this method because it is. We report a green, simple and efficient approach for the production of graphene oxide go by ultrasonic assisted electrochemical exfoliation of graphite rods, and by using improved hummers graphene oxide igo as an electrolyte. Nov 17, 2016 graphene oxide has many applications such as in electronic devices, as storage energy device, biosensor, biomedical application, water purification, coating technology, as a composite and paper like materials. Synthesis of graphenebased nanosheets via chemical reduction. Graphene nanosheets by lowtemperature thermal reduction of. Feb 09, 2016 thermal exfoliation and reduction of graphite oxide also produce goodquality graphene, generally referred to as reduced graphene oxide rgo. Boehm reported producing monolayer flakes of reduced graphene oxide in 1962.
Efficient synthesis of graphene oxide and the mechanisms of. Cvd, exfoliation, graphene, graphene oxide, synthesis 1. Herein, we show that molecular selfassembly process can be used as a useful tool to exfoliate reduced graphene oxide rgo, resulting in hybrid materials with improved physical properties. The excellent mechanical, electrical, thermal, optical properties and high specific surface area of graphene and manipulation of these properties via chemical. Massive production of graphene oxide from expanded graphite arxiv. New insight of high temperature oxidation on selfexfoliation. As discussed, the liquid phase exfoliation process can easily be scaled up. Coarse grained models of graphene and graphene oxide for use. Colloidal graphene ink was prepared by diluting graphene in ndimethylformamide with a high concentration at sonication state 15. Graphene synthesis, properties, and applications cheap tubes. We demonstrated that the graphite did not need to be oxidized to such a deep degree as described in hummers method because the space distance increased little when the oxidation proceeded to a certain extent and the obtained graphite oxides gtos could be fully. Highefficiency exfoliation of largearea monolayer graphene oxide.
Synthesis of graphene oxide go by modified hummers method. Synthesis and exfoliation of isocyanatetreated graphene. It has the association of both the thermal and electric conductivities at remarkably great1. As of 2014 exfoliation produced graphene with the lowest number of defects and highest electron mobility.
Pdf today, research on graphene and other twodimensional sp2hybridized carbon nanomaterials has tremendously impacted the areas of. Synthesis of graphene oxide through ultrasonic assisted. The silverson model consists of manual control system, rotor and stat. Synthesis and fabrication of graphene and graphene oxide. The electrolyte used was sodium dodecyl sulphate sds aqueous solution at various concentrations from 0. Reduction temperature plays the most crucial role as it controls the quality of reduced graphene oxide in terms of weight percentage of carbon and lattice defect. In downstream processing, ultrasonic dispersers produce highperformance graphene oxide polymer composites.
Graphene oxides gos with large sheets and more perfect aromatic structure were prepared by a novel modified hummers method. A number of functionalized graphite oxides were prepared by treatment of graphite oxide go with organic isocyanates. Sep 15, 2017 graphene oxide go is a twodimensional material derived from graphene by decorated several oxygenated functional groups on its basal planes and at its edges. Dec 01, 2019 the exfoliation of graphite oxide and the interactions between graphene and graphene oxide cause the 001 peak towards lower. Natural flake graphite nfg was procured from loba chemie india having a mean size of 60 mesh and purity of 98%. Onestep synthesis and characterization of reduced graphene oxide. Role of peroxide ions in formation of graphene nanosheets by. By treating graphite oxide powders in a commercial microwave oven, reduced graphite oxide materials could be readily obtained within 1 min. Graphene oxide go has been initially prepared by a modified hummersmethod. Dispersed graphene oxide go nanosheets in water were synthesized via a new approach involving sonicationfree exfoliation, as promoted by repetitive simple freezethaw cycles. For instance, a liquid phase exfoliation could be demonstrated as a technique to produce high quality, oxide free and defectfree graphene sheets upon treatment with nmethyl2pyrrolidone nmp and a subsequent thermal treatment at 800c oh et al. Graphene oxide ultrasonic exfoliation and dispersion. Graphene is different in size and structure because of oxidized layered of graphene oxide hence. Layerengineered largearea exfoliation of graphene science.
Research article preparation and characterization of. The second step is the oxidation step, where oxidation of exfoliated graphene sheets. Pdf microwave assisted exfoliation and reduction of. Exfoliation of graphite oxide in water without sonication. Graphite materials were exfoliated by a single step electrochemical exfoliation. Sep 23, 2016 oxidation of graphite and its subsequent exfoliation into monolayered graphene oxide go with large lateral dimensions 57 produce an exfoliation yield of 100%. Graphene oxide go is a twodimensional material derived from graphene by decorated several oxygenated functional groups on its basal planes and at its edges. Go is usually prepared by exfoliating graphite oxide. These cycles consist of rapid freezing of an aqueous solution containing graphite oxide and subsequent thawing of the resultant solid. The next three sections describe the three types of chemical methods. Thermal reduction of graphene oxide chemical conversion of go to reduced graphene oxide trgo was done by thermal exfoliation using rfcvd. Coarse grained models of graphene and graphene oxide for. In the rst step, bulk graphite would be oxidized by chemical oxidation to become hydrophilic graphite oxide go.
Part of the oil, gas, and energy commons, and the power and energy commons. Synthesis of graphene oxide go by modified hummers. The effect of sds concentrations on the morphology of go samples were characterized using field emission scanning electron microscopy fesem, energy dispersive xray. A simple, green and costeffective approach has been reported to synthesize highquality graphene oxide go flakes via electrochemical exfoliation of pencil cores in aqueous electrolytes. Pyrolytic graphite, electrochemical, intercalation, exfoliation, graphene oxide nano sheets, afm, tem. Simple synthesis of large graphene oxide sheets via. Achieving single layers typically requires multiple exfoliation steps, each producing a slice with fewer layers, until only one remains. Visualization of the reduction and exfoliation of graphene oxide in a microwave oven. Geometrydependent thermal reduction of graphene oxide solid. Pdf simple preparation of exfoliated graphene oxide sheets via. Reduction and exfoliation of graphene oxide via microwaves. Role of peroxide ions in formation of graphene nanosheets. Exfoliation of reduced graphene oxide with selfassembled. We report a simple yet versatile method to simultaneously achieve the exfoliation and reduction of graphite oxide.
1145 1474 1350 1054 44 274 1012 1813 892 410 1571 1574 328 615 596 1515 1666 1864 580 1454 355