浮动催化体系中碳纳米管的生长机理

!垡堕竺皇!!:鉴,!!!!:鱼巴!尘竺!!!!!堕墨!!!!!!!!!!!!!!!竺!里!!!!!!曼g!!!!!!璺!!!!曼翌..————————三!!!一Growthmechallismofcarb明naIlotubesinn的tingcatalyStsystem

ZHUChun—ve,XIEZi一1i,GUoKull-min

(R础rchInstltute。fchemjcalDefencetB蜘i“g100083?china)

Abstract:Vaporphascnucleation(VPN)growthmechanismwasprop05edtoexplainthegrowthofcarbonnanotubes

inf108tlngcatalystsystemActlvecarbonavailableforthegrowthofCNTsinfloatingcatalystsystemcame

fromthepyrolysIsofbenzene.Catalvstparticle,partiallycoveredwithsulphur.actedasthenucIeationceⅡterfor

SWNTs.(bntinuousradiaIgrow血oiSWNTsandEradualgraphhizationresuhedintheformationofMWNTs.TheVPNgrowthmechaIlismcanbeu3edtowellexDlalnthecharacteristicsofCNTsinfloatingcataIystsystem.

Keywords:衄rb∞n蛐otube}订舳tingcatalystsystem;growthmechanism

CLCnumber:TQ342.742Documentcode:AArtickID;1001—9731(2005)11一1789—05lIntrOducti帅

Carbonnanotubes(CNTs)hasbeenpaidintensiveattentlonfortheiruniquechemicalandphysicalproper

tlcsandpotentialapplications[卜”.Chemical

vapordep。sitlon(CVD)waseverusedtogrow

ca曲。nflbersfrom

hydrocarbonL“and1ateronwasdevelopedtoprepareCNTs,whichwasknownassupportedcatalystmethod。~Inor出rtocontrolthediameterandchiralilyofCNTs,whichdeterminethepropertiesofCNTs¨川,growlhmechanismshavebeenstudiedandachievementshavebeenmade[8~11].Floatingcatalystmethodisthemostprosperouspr。cessforthelargescaIesynthesisofCNTs[】2].Butgrowth

mechanismisstillunclear.Thegr。wthⅡ1echanismofCNTsfr。msuppo¨edcatalystmethodisnolongerapplicablef。rLhefloatingcatalystsystem,be—causenocatalys卜supportinteractlonexistsfortheabsenceofcatalystsupport.

Basedonthefactthatchemicalreactlonthalcarbo矿bearinggasundergoestoproducefreecarbonlsnotgenerallykn。wntodeterminethecarbonmorph0109y,Kukovitskyetal_[13]reported

VLSgrowthofcarbonnanotubesfromthevaporcombiningsupportedcatalystandarcdischarge,theyusedarcdischargetoproVidefreecarbonfortheCNTstogrowonsupportedcatalyst.HirokiAgoetaL[14]alsorep。rtedthatgasphasesyn—thesisofsingle—wallcarbonnanotubesfollowedsomewhatsimilarmechanismwithlaser-ablationtechnique.Re—centlv,onthebasisofVLSgrowthm。deL[I…,J.Gavilleteta1.‘埘reportedacommongrowthmechanismforSWNTsfromarcdischar*盲and1aserablation,whichmightbethecommongrowthmechanismfordifferenttechniques.Allthesefactshintedthatlherenlightbeacommo“growthmechanismforvaporphasegrowthtechniques,suchasarc-discharge,1aserablationandfloatingcatalystmethod.

F。rhlghtemperaturemethods(suchasarcdischargemethod),arcisnecessarytoprovldetemperatureasH叠has3000~5000K[17]fortheca曲onanodetovaporize.Butmediumreactiontemperatureisneededtoobtainhlghestyieldforarcdischargemethod[1“,whichisclosetothetemperaturerequiredforthedec。mpositionofhydrocarbonsandgrowthofCNTsforthefloatingcatalystmethod[12’1¨.ThecatalystparticleinarcdischargeandlaserablationprocessisindispensabIeforthegrowthofSWNTs[16].TheformationofMWNTshasbeenat_t打butedt。otherparameterstsuchassp。tweldingofadat。m5betweenadjacent】8yers0201duetoextremeconditlons.ButforthesynthesisofbothSWNTsandMWNTsinfloatingcatalystsystem,catalystisnecessary,forwhich,noreas。nableexplanationhasbeenreportedyet.WeinvestigatedthegrowthofCNTsinatwostageh()一z。ntalfloati“gcatalystsystem.Vap。‘phasenuckati。n(VPN)growthmodel,adaptedfromVLSmodel,jsproposedforthegrowthofCNTsinthesystem.ThismodelmightcontributetothegeneralgrowthmechanismofCNTsfromallvaporphasegrowthtechniques.

2Experimental

Tw。stageho“zontalfloati“gcatalystapparatuswasusedtoprepareCNTs,wherelowtemperaturestage

*Foundationjtem:TheChlnaNatiollalM由orStateBasicResearchporgram(G2000026403)

Receiveddate:2005一Ol—04M0djfieddate:2005—03一15Co嗍poⅡdi“g邪thorlZHUChun-ye

BiograPhy:ZHUChun,ye(1974一).maJe,Ph.D,engagedjnthep‘印arationandappljcationofnanocarbonnlat“日ls. 万方数据

万方数据

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