FOCUS ON EMERGING TECHNOLOGY

SYNTHESIS & APPLICATIONS

FOCUS ON EMERGING TECHNOLOGY GRAPHENE SYNTHESIS & APPLICATIONS

OVERVIEW:Graphene is a single atomic layerof carbon atoms tightly packed in a two-dimensional honeycomblattice. This novel material isatomically thin, chemically inert,consists of light atoms, andpossesses a highly orderedstructure. Graphene is elec tricallyand thermally conductive, and isthe strongest material evermeasured. These remarkableproperties make graphene theideal support film for electronmicroscopy.

An atomic-resolution image of a clean andstructurally perfect graphene sheet synthesized bythe substrate-free gas-phase method. Individualcarbon atoms appear white in the image.

Elemental analysis by FT-IR reveals that thesynthesized graphene sheets are free ofdetrimental oxygen functionalities. The FT-IRspectrum of synthesized graphene is similar to thatof highly oriented pyrolytic graphite (HOPG).

A typical TEM image of graphene sheets freelysuspended on a lacey carbon TEM grid.

SYNTHESIS:the substrate-free gas-phase method

Graphene is a single atomic layer of carbon atomstightly packed in a two-dimensional honeycomblattice. The novel material has generated greatinterest throughout the scientific and technologicalcommunity because of its remarkable properties andnumerous potential applications. However, obtainingpure and highly ordered graphene has been achallenge. Small quantities of ultrahigh-qualitygraphene have been isolated through an unwieldyand time-consuming process involving themechanical exfoliation of highly oriented pyrolyticgraphite. Alternative methods require substrates orgraphite to create atomically-thin sheets, and thesetechniques involve multiple steps, expensivesubstrates, or non-ambient conditions. Furthermore,the sheets produced by these alternative methodsexhibit defects, disorder, and oxygen functionalitiesthat have a detrimental effect on the properties ofgraphene.

The substrate-free gas-phase method is the first andonly process that can synthesize ultrahigh-qualitygraphene in a single step, without the use ofsubstrates or graphite [1]. Graphene sheets arecreated through the delivery of liquid alcohol dropletsdirectly into atmospheric-pressure microwave-generated plasmas. Extensive characterizationof the synthesized graphene has proven thatthe sheets are oxygen-free and exhibit ahighly ordered structure [2]. The grapheneproduced by this unique method canimmediately be utilized for graphene applications.

0.14 nm

APPLICATION:direct imaging of soft and hardnanomaterials

The interfaces between soft and hard nanomaterialshave been the subject of extensive research.Nanoparticles coated with molecular layers havebeen shown to self-assemble into novel structuresthat could potentially be used in electronics, sensors,and photonics. Self-assembly is influenced by thenature of molecular coatings and thus more detailedcharacterization of these soft materials is needed.However, imaging surface molecules and theirinterfaces with nanoparticles at the atomic scale is asignificant challenge.

The transmission electron microscope (TEM) imagingof functionalized nanoparticles has been attempted.However, it has not been possible to observemolecular surface layers and their interfaces withnanoparticles at the atomic level. Modern aberration-corrected TEMs can produce atomic-resolutionimages of soft and hard nanomaterials. However,conventional TEM support films (e.g. ultrathinamorphous carbon) limit the capabilities of theseadvanced microscopes because they contribute tooverall electron scattering and diminish the contrastof low-atomic number specimens. The TEM imagingof the interfaces between soft and hardnanomaterials therefore requires better support filmsthat have a lower dynamical interference with animaging object [3].

Graphene is the ideal TEM support film. The materialpossesses a highly ordered structure and isatomically thin, chemically inert, structurally stable,and electrically and thermally conductive. Theultrahigh-quality graphene produced by thesubstrate-free gas-phase method [1, 2] has enabledthe unsurpassed TEM imaging of organic moleculesand the interfaces between soft and hardnanomaterials. The pure and highly-ordered sheetswere used as a near-invisible support film to directlyimage the atoms in a gold nanoparticle and itssurrounding citrate coating [3]. The results showedthat the synthesized graphene can be used to directlyobserve nanoparticles functionalized with a diverserange of molecular coatings, such as proteins andDNA

An atomic-resolution image of a gold nanoparticleand its surrounding citrate capping agent on asynthesized graphene support film

A low-magnification image of a (1) goldnanoparticle on a (2) transparent synthesizedgraphene support film, (3) the vacuum, and (4) a lacey carbon support.

OTHER POTENTIAL APPLICATIONS:biodevices • single molecule gas detection • graphene nanoribbons

integrated circuits • transparent conducting electrodes • ultracapacitors

Electron Microscopy SciencesP.O. Box 5501560 Industry Rd.Hatfield, Pa 19440Tel: (215) 412-8400Fax: (215) 412-8450email: sgkcck@aol.comwww.emsdiasum.com

We offer ultrahigh-qualitygraphene that is producedthrough the substrate-free gas-phase method[1]. The graphenecreated by this techniquepossesses a highly orderedstructure that is composed of99% carbon by mass (1%hydrogen)[2]. This graphene wasused to directly image goldnanoparticles and their organicsurface molecules in bothconventional and atomic-resolution TEMs at a level thatgreatly surpasses any currentTEM support film[3]. Our graphene provides aninvisible, crystalline backgroundthat enables the unrivaled TEMcharacterization of organic andinorganic nanomaterials.

[1] Dato et al., “Substrate-Free Gas-Phase Synthesis ofGraphene Sheets”, Nano Letters 8, 2012–2016 (2008).[2] Dato et al., “Clean and highly ordered graphenesynthesized in the gas phase”, Chemical Communica-tions, 6095–6097, (2009).[3] Lee et al., “Direct Imaging of Soft-Hard InterfacesEnabled by Graphene”, Nano Letters 9, 3365–3369(2009).

Electron Microscopy SciencesP.O. Box 5501560 Industry Rd.Hatfield, Pa 19440Tel: (215) 412-8400Fax: (215) 412-8450email: sgkcck@aol.comwww.emsdiasum.com

Graphene products come availablein five different ways, allowing you tochoose which is best for you:a) As a solution of 0.1 mg Graphene in 1 ml of

Ethanol. A homogeneous solution will takeless than 30 seconds to create by sonicatingthe Graphene-solvent mixture. One is able tocoat their own grids using this solution.

b) As Graphene-enhanced lacey carbon TEMgrids. 200 and 300 mesh. These grids arecreated by coating our existing lacey carbongrids with graphene. Through a unique dropmethod, solution is dispersed onto theLacey Carbon Grid.

c) As dry, synthesized Graphene powder, 1 mg.d) As Graphene-coated TEM grids in 200, 300

and 400 mesh.e) As a Graphene film coating on a substrate to

create a thin film of graphene.

ORDERING INFORMATION:EMS # Product Description QuantityGF1200 0.1 mg Graphene

in 1 ml of Ethanol eachGF1201 Graphene-Enhanced

Lacey Carbon TEM Grid 200 # Cu each

GF1202 Graphene-Enhanced Lacey Carbon TEM Grid 200 # Ni each

GF1203 Graphene-Enhanced Lacey Carbon TEM Grid 300 # Cu each

GF1204 Graphene-Enhanced Lacey Carbon TEM Grid 300 # N each

GF1205 Synthesized Graphene Powder, 1 mg each