專業(yè)英語w4小組展示-g4團隊報告等

Graphene:FromfundamentaltoFutureApplicationsYueZhipeng、ZhaoLeleandGaoPengfeiSunYat-senUniversityContent

Introductiontographene.PreparationandcharacterizationgraphenePotentialapplicationofgrapheneConclusionsBriefhistoryofgrapheneThetermgraphenefirstappearedin1987todescribesinglesheetsofgraphiteasoneoftheconstituentsofgraphiteintercalationcompounds(GICs).Largergraphenemoleculesorsheets(sothattheycanbeconsideredastrueisolated2Dcrystals)cannotbegrowneveninprinciple.Inthe1930s,LandauandPeierls(andMermin,later)showedthermodynamicsprevented2-dcrystalsinfreestate,anarticleinPhysicsTodayreads:"Fundamentalforcesplaceseeminglyinsurmountablebarriersinthewayofcreating[2Dcrystals]...Nascent2Dcrystallitestrytominimizetheirsurfaceenergyandinevitablymorphintooneoftherichvarietyofstable3Dstructuresthatoccurinsoot.Butthereisawayaroundtheproblem.Interactionswith3Dstructuresstabilize2Dcrystalsduringgrowth.Soonecanmake2Dcrystalssandwichedbetweenorplacedontopoftheatomicplanesofabulkcrystal.Inthatrespect,graphenealreadyexistswithingraphite...OnecanthenhopetofoolNatureandextractsingle-atom-thickcrystallitesatalowenoughtemperaturethattheyremaininthequenchedstateprescribedbytheoriginalhigher-temperature3Dgrowth.”In2004:AndreGeimandKostyaNovoselovatManchesterUniversitymanagedtoextractsingle-atom-thickcrystallites(graphene)frombulkgraphite:Pulledoutgraphenelayersfromgraphiteandtransferredthemontothinsilicondioxideonasiliconwaferinaprocesssometimescalledmicromechanicalcleavageor,simply,theScotchtapetechnique.Since2004,anexplosionintheinvestigationofgrapheneintermofsynthesis,characterization,propertiesaswellasspecificalpotentialapplicationwerereported.IntroductiontographeneGrapheneisaone-atom-thickplanarsheetofsp2-bondedcarbonatomsthataredenselypackedinabcrystallatticeThename‘graphene’comesfromgraphite+-ene=grapheneHighresolutiontransmissionelectronmicroscopeimages(TEM)ofgrapheneIntroductiontographeneMolecularstructureofgrapheneA.K.Geim&K.S.Novoselov.Theriseofgraphene.NatureMaterialsVol.6,183-191(2007).IntroductionIntroduction-ElectronicpropertiesThermalpropertiesMechanicalpropertiesOpticalpropertiesPropertiesofgrapheneElectronicpropertiesHighelectronmobility(atroomtemperature~200.000cm2/(V·s),,ex.SiatRT~1400

cm2/(V·s),carbonnanotube:~100.000cm2/(V·s),organicsemiconductors(polymer,oligomer):<10cm2/(V·s)

Resistivityofthegraphenesheet~10?6Ω·cm,lessthantheresistivityofsilver(Ag),thelowestresistivitysubstanceknownatroomtemperature.Whereυdisthedriftvelocityinm/s(SIunits)EistheappliedelectricfieldinV/m(SI)μisthemobilityinm2/(V·s),inSIunits.MaterialElectricalConductivity(S·m-1)NotesGraphene~108Silver63.0×106BestelectricalconductorofanyknownmetalCopper59.6×106Commonlyusedinelectricalwireapplicationsduetoverygoodconductivityandpricecomparedtosilver.Annealed

Copper58.0×106Referredtoas100%IACSorInternationalAnnealedCopperStandard.Theunitforexpressingtheconductivityofnonmagneticmaterialsbytestingusingtheeddy-currentmethod.Generallyusedfortemperandalloyverificationofaluminium.Gold45.2×106Goldiscommonlyusedinelectricalcontactsbecauseitdoesnoteasilycorrode.Aluminium37.8×106Commonlyusedforhighvoltageelectricitydistributioncables[citationneeded]Seawater4.8Correspondstoanaveragesalinityof35g/kgat20°C.[1]Drinkingwater0.0005to0.05ThisvaluerangeistypicalofhighqualitydrinkingwaterandnotanindicatorofwaterqualityDeionizedwater5.5×10-6Conductivityislowestwithmonoatomicgasespresent;changesto1.2×10-4uponcompletede-gassing,orto7.5×10-5uponequilibrationtotheatmosphereduetodissolvedCO2

[2]JetA-1Kerosene50to450×10-12[3]n-hexane100×10-12Air0.3to0.8×10-14MaterialThermalconductivity

W/(m·K)SilicaAerogel0.004-0.04Air0.025Wood0.04-0.4HollowFillFibreInsulationPolartherm0.042Alcoholsandoils0.1-0.21Polypropylene0.25[6]Mineraloil0.138Rubber0.16LPG0.23-0.26Cement,Portland0.29Epoxy(silica-filled)0.30Epoxy(unfilled)0.59Water(liquid)0.6Thermalgrease0.7-3Thermalepoxy1-7Glass1.1Soil1.5Concrete,stone1.7Ice2Sandstone2.4Stainlesssteel12.11~45.0Lead35.3Aluminium237(pure)

120—180(alloys)Gold318Copper401Silver429Diamond900-2320Graphene(4840±440)-(5300±480)ThermalpropertiesIntroductionPropertiesofgraphene-HighYoung’smodulus(~1,100Gpa)Highfracturestrength(125Gpa)-Monolayergrapheneabsorbsπα≈2.3%ofwhitelight(97.7%transmittance),whereαisthefine-structureconstant.MechanicalpropertiesOpticalpropertiesArepresentationofadiamondtipwithatwonanometerradiusindentingintoasingleatomicsheetofgraphene

(Science,321(5887):385)-Grapheneisasthestrongestmaterialevermeasured,some200timesstrongerthanstructuralsteelPreparationandCharacterizationGraphenePreparationmethodsTop-downapproach(Fromgraphite)Bottom-upapproach(Fromcarbonprecursors)Bychemicalvapourdeposition(CVD)ofhydrocarbonByepitaxialgrowthonelectricallyinsulatingsurfacessuchasSiCTotalOrganicSynthesisMicromechanicalexfoliationofgraphite(Scotchtapeorpeel-offmethod)Creationofcolloidalsuspensionsfromgraphiteoxideorgraphiteintercalationcompounds(GICs)Top-downapproach(Fromgraphite)GraphiteoxidemethodGraphiteintercalationcompoundDirectexfoliationofgraphitePreparationmethodsGraphenesheetsionic-liquid-modifiedbyelectrochemistryusinggraphiteelectrodes.DirectexfoliationofgraphiteGraphiteintercalationcompound

Schematicdiagramshowingtheintercalationandexfoliationprocesstoproducethinslabsofgraphite.Potassiumisinsertedbetweenthelayersandreactedviolentlywithalcohols.Theexfoliatedslabsare~30layersthick.MoreintercalationforbetterexfoliationtomonolayersGraphiteoxideGraphiteoxidemethodBottomupapproach(fromcarbonprecursors)OpticalimageofapatternedNifilmonSiO2/Si.CVDgrapheneisgrownonthesurfaceoftheNipattern(b)OpticalimageofgrowngraphenetransferredintactfromtheNisurfacein(a)toanotherSiO2/SisubtrateCVDmethodTotalOrganicSynthesisPolyacyclicaromatichydrocarbons(PAHs)mayofferaground-upsynthesisofgrapene(a)ChemicalstructureofPAHs(b)TEMofnanoribbonsynthesizedbyresearcherCharacterizationmethodsScanningProbeMicroscopy(SPM)-Atomicforcemicroscopes(AFMs)-Scanningtunnelingmicroscopy(STM)RamanSpectroscopyTransmissionelectronMicroscopy(TEM)X-raydiffraction(XRD)AtomicforcemicroscopyimagesofagraphiteoxidefilmdepositedbyLangmuir-BlodgettassemblySTMimageofgraphiteshowingonlythethreecarbonsthateclipseaneighborinthesheetdirectlybelow.Incontrast,allsixcarbonsareequivalentandthusvisibleinmechanicallyexfoliatedsingle-layergrapheneTEMimagesshowthenucleationof(c)one,(d)three,or(e)fourlayersduringthegrowthprocessRamanSpectroscopyTransmissionelectronMicroscopy(TEM)Ramanspectroscopyisapowerfuldiagnostictoolforthestudyofgraphene.BoththeG(near1584/cm)andG’(near2700/cm)bandsundergosignificantchangesduetothethicknessofABstackedflakes,asproducedbymechanicalexfoliationXRDpatternsof400umdiametergraphiteflakesoxidizedforvariouslengthsoftime.X-raydiffraction(XRD)Potentialapplicationofgraphene-Singlemoleculegasdetection-Graphenetransistors-Integratedcircuits-TransparentconductingelectrodesforthereplacementofITOectSpaceElevatorScientistsproposedtheideaofthespaceelevatorInthelastcentury.Thebiggestdifficultyistofindthesuperhardmaterialtoformulatethecable.GraphenemeettheneedofthestructureofspaceelevatorMakeputerinsteadofsiliconGrapheneisknowntohavethebestconductiveproperty.dotoit’slowresistivity,electronmobilityisfasterthanothers.solotsofenergylostincollisionofatomsandmoleculesissaved.Becauseofthesepropertiesofgraphene,itcanimprovethecurrenthighfreque