简介：Bymeansoffirst-principlesdensityfunctionaltheory(DFT)calculationsandmoleculardynamics(MD)simulations,aseriesofcoronalmulti-walledsiliconnanotubes(MWSiNTs)withoutorwithhydrogenterminationsaresystematicallyidentified.Notably,coronalMWSiNTs,wheretheinteractionbetweenthewallsispreferablethroughcovalentbondsratherthanweakinteraction,showbetterstabilitythanCNT-likeSiNTs.Moreover,theyexhibitgoodelasticitywithsmallYoung’smodulus.Theinvestigationoftheelectronicstructuredemonstratesthattheypresentmetalliccharacteristics,whichisinstrikingcontrasttobulksilicon.Thus,theMWSiNTsmayfindimportantapplicationsinelectronicdevices.

简介：Usingfirst-principlescalculations,thecontactbetweenthescandium(Sc)andsemiconductingcarbonnanotube(CNT)isinvestigated.Thisisoneofthebestqualityofn-typecontacts.Twojunctionmodelswith(8,0)CNTonlow-indexScsurfacesareconstructedtoelucidatethestructuralandelectronicpropertiesofSc/CNTjunctions.AnalysesbasedondensityofstatesandchargedifferencerevealthatstrongchemicalbondsareformedbetweenScandCatomsduetohybridstatesofSc3dstateandC2πstate.WithrespecttoTi(0001)/CNTjunction,wefindthedipolelayerformedattheinterfaceofSc(0001)/CNTiscomparablewiththatofTi(0001)/CNTbutgivesanegativebarrierattheinterface.ThisindicatesthattheexcellentcontactpropertiesofScmetalelectrodearecausedbyitslowworkfunctionandexcellentbindingwithCNT.

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简介：我们学习分子的氧的绑定到一(5，0)单身者原文如此围了nanotube，借助于密度功能的计算。在SiCNT表面上的地点的硅和碳原子的等边六角形的中心是为O2分子的最稳定的吸附地点，与一个有约束力的精力?38.22eV和1.698的平均SiO有约束力的距离?。我们也与abinitio测试了O2adsorbedSiCNT/CNT的稳定性在房间温度被执行了的分子的动力学模拟。而且，单个围的碳nanotubes上的O2的吸附被调查了。我们的第一原则的计算预言硅碳化物nanotubes的O2吸附的能力比碳nanotubes的好一些。这可能为煤气的察觉和精力存储有潜力。

简介：Thisworkreportsafeasiblesynthesisofhighly-dispersedPtandPt-Fenanoparticlessupportedonmultiwallcarbonnanotubes(MWCNTs)withoutFeandmultiwallcarbonnanotubeswithiron(MWCNTs-Fe)whichappliedaselectrocatalystsformethanolelectrooxidation.APtcoordinationcomplexsaltwassynthesizedinanaqueoussolutionanditwasusedasprecursortopreparePt/MWCNTs,Pt/MWCNTs-Fe,andPt-Fe/MWCNTsusingFeCl24H2OasironsourcewhichwerenamedS1,S2andS3,respectively.Thecoordinationcomplexofplatinum(TOA)2PtCl6wasobtainedbythechemicalreactionbetween(NH4)2PtCl6withtetraoctylammoniumbromide(TOAB)anditwascharacterizedbyFT-IRandTGA.ThematerialswerecharacterizedbyRamanspectroscopy,SEM,EDS,XRD,TEMandTGA.TheelectrocatalyticactivityofPt-basedsupportedonMWCNTsinthemethanoloxidationwasinvestigatedbycyclicvoltammetry(CV)andchronoamperometry(CA).Pt-Fe/MWCNTselectrocatalystsshowedthehighestelectrocatalyticactivityandstabilityamongthetestedelectrocatalystsduetothattheadditionof'Fe'promotestheOHspeciesadsorptionontheelectrocatalystsurfaceatlowpotentials,thus,enhancingtheactivitytowardthemethanoloxidationreaction(MOR).

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简介：Wepresentnumericalcalculationoftheimpactofelectron-electroninteractiononthebehaviorofdensityofstatesandopticalpropertiesofBeO,SiCandBoron-Nitridenanotubesandsheets.Hubbardmodelhamiltonianisappliedtodescribethedynamicsofelectronsonthelatticestructureofthesescompounds.TheexcitationspectrumofthesysteminthepresenceoflocalelectronicinteractionshasbeenfoundusingmeanSeldapproach.WefindthebandgapwidthinbothopticalabsorptionanddensityofstatesreduceswithlocalHubbardelectronicinteractionparameter.Theabsorptionspectraexhibitstheremarkablepeaks,mainlyowingtothedivergencebehaviorofdensityofstatesandexcitoniceffects.AlsowecompareopticalabsorptionfrequencybehaviorofBeO,SiCandBoron-Nitridenanotubeswitheachother.FurthermoreweinvestigatetheopticalpropertiesofBeOandSiCsheets.Anovelfeatureofopticalconductivityofthesestructuresisthedecreaseoffrequencygapintheopticalspectrumduetoelectronicinteraction.

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简介：K-promotediron/carbonnanotubescomposite(i.e.,FeK-OX)waspreparedbyaredoxreactionbetweencarbonnanotubesandK_2FeO_4followedbythermaltreatmentsonapurposeastheFischer–Tropschcatalystforthedirectconversionofsyngastolowerolefins.ItscatalyticbehaviorswerecomparedwiththoseoftheothertwoFe-IMandFeK-IMcatalystspreparedbyimpregnationmethodfollowedbythermaltreatments.ThenovelFeK-OXcompositecatalystisfoundtoexhibithigherhydrocarbonselectivity,lowerolefinsselectivityandchaingrowthprobabilityaswellasbetterstability.ThecatalyststructureperformancerelationshiphasbeenestablishedusingmultipletechniquesincludingXRD,Raman,TEMandEDSelementalmapping.Inaddition,effectsofadditionalpotassiumintotheFeK-OXcompositecatalystontheFTOperformancewerealsoinvestigatedanddiscussed.Additionalpotassiumpromotersfurtherendowthecatalystswithhigheryieldoflowerolefins.Theseresultsdemonstratedthattheintroductionmethodofpromotersandironspeciesplaysacrucialroleinthedesignandfabricationofhighlyactive,selectiveandstableiron-basedcompositecatalystsfortheFTOreaction.

简介：Differentoxygenandnitrogencontainingfunctionalgroupswerecreatedonthesurfaceofthemultiwalledcarbonnanotubes.Themulti-walledcarbonnanotubesweretreatedinultrasonicbathwithsulfuricornitricacid.Furthermorethesurfacetexturewasmodifiedbyincreaseoftheroughness.Inparticularaftertreatmentwiththeoxidizingnitricacid,incomparisontotheH_2SO_4orultra-sonictreatedsamples,cratersandedgesaredominatingthesurfacestructures.Manganeseoxidewasdepositedonthemultiwalledcarbonnanotubesbyprecipitationmechanism.Variousmanganeseoxidesareformedduringthedepositionprocess.Thesampleswerecharacterizedbyelementalanalysis,microscopy,thermalanalysis,Ramanspectroscopy,andbythezetapotentialaswellasX-raydiffractionmeasurements.Itwasshownthatthedepositedmanganeseoxidesarestabilizedratherbysurfacetextureofthemulti-walledcarbonnanotubesthanbycreatedfunctionalgroups.

简介：Dopingeffectsofmanganese(Mn)oncatalyticperformanceandstructureevolutionofNiMgOcatalystsforsynthesisofmulti-walledcarbonnanotubes(MWCNTs)frommethanewereinvestigatedforthefirsttime.AdditionofMninNiMgOcatalystcangreatlyimprovetheMWCNTsyield.Mn0.2NiMgOcatalystamongthetestedonesgivesthehighestMWCNTsyieldas2244%,whichistwotimeshigherthanthatofthecatalystwithoutMn.Thestructureevolution,reductionbehaviorsandsurfacechemicalpropertiesofMnNiMgOcatalystswithvariousMncontentswerestudiedindetail.ItwasfoundthatthestablesolidsolutionofNiMgO2formedinNiMgOcatalystwasdisturbedbytheadditionofMn.Instead,anothersolidsolutionofMnMg6O8isformed.MoreamountofNicanbereducedanddispersedonthecatalystsurfacetobeactedasactivesites.Importantly,thechangesofNicontentonthesurfacearecorrelatedwiththeNiparticlesizeandtheouterdiameterofMWCNTs,suggestingthecontrollablesynthesisofMWCNTsoverMnNiMgOcatalysts.

简介：Shortpulsedfiberlasershavebeenwidelymadeusingsingle-walledcarbonnanotubesasasaturableabsorber(SA).However,mostofthecurrentlyuseddevicescanonlyoperateinonedeterminedoperationstatewithanunchangeablemodulationSAdepthinthecavity,whichsignificantlylimitstheirapplicationinphotonicdevices.Inthispaper,well-alignedcarbonnanotubearraysaresynthesizedusingzeoliteAlPO4-5asatemplate,whichfeaturesanisotropicopticalabsorption.Thelinearopticalabsorptionoftheas-synthesizedcarbonnanotubearrayscaneasilybetunedbyadjustingapolarizationcontroller,thusprovidingatunablemodulationdepthforthecarbonnanotubeSA.ByexploitingthisSAinanerbium-dopedfiberlasercavity,bothQ-switchedandmodelockedpulsedlasersareachievedbysimplyadjustingapolarizationcontrollerunderafixedpumppowerof330mW.Inaddition,therepetitionrateoftheQ-switchingandpulsedurationofthemode-lockingcanbetunedaccordingtothevariationofmodulationdepth.Moreover,solitonmoleculescanbeobtainedwhenthemodulationdepthoftheSAis4.5%.

简介：Wedemonstrateanallfiberpassivelymode-lockedlaseremittingaradiallypolarizedbeambyusingafew-modefiberBragggratingtoachievemodeselectionandspectrumfiltering.Anoffsetsplicingofsingle-modefiberwithfour-modefiberisutilizedasamodecouplerinthelasercavity.Carbonnanotubesareintroducedintothelasercavityasthesaturableabsorbertoachieveself-startmodelocking.Thelaseroperatesat1547.5nmwithanarrowspectrumwidthof0.3nmat30dB.Theemittedmode-lockedpulseshaveadurationof22.73psandrepetitionof10.61MHz.Aradiallypolarizedbeamhasbeenobtainedwithhighmodepuritybyadjustingthepolarizationinthelasercavity.

简介：Industrialgrademulti-walledcarbonnanotubes(IG-MWCNTs)arealow-costsubstituteforcommerciallypurifiedmulti-walledcarbonnanotubes(P-MWCNTs).Inthiswork,IG-MWCNTswerefunctionalizedwithtetraethylenepentamine(TEPA)forCO2capture.TheTEPAimpregnatedIG-MWCNTswerecharacterizedwithvariousexperimentalmethodsincludingN2adsorption/desorptionisotherms,elementalanalysis,X-raydiffraction,Fouriertransforminfraredspectroscopyandthermogravimetricanalysis.BoththeadsorptionisothermsofIGMWCNTs-nandtheisostericheatsofdifferentadsorptioncapacitieswereobtainedfromexperiments.TEPAimpregnatedIG-MWCNTswerealsoshowntohavehighCO2adsorptioncapacitycomparabletothatofTEPAimpregnatedP-MWCNTs.TheadsorptioncapacityofIG-MWCNTsbasedadsorbentswasintherangeof2.145to3.088mmol/g,dependingonadsorptiontemperatures.Havingtheadvantagesoflow-costandhighadsorptioncapacity,TEPAimpregnatedIG-MWCNTsseemtobeapromisingadsorbentforCO2capturefromfluegas.

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简介：Forthesynthesisofsingle-walledcarbonnanotubes(SWCNTs)fromCH4overaFe/MgOcatalyst,weproposedacoupledDowner-turbulentfluidized-bed(TFB)reactortoenhancetheselectivityandyield(orproductionrate)ofSWCNTs.Bycontrollingaveryshortcatalystresidencetime(1-3s)intheDowner,onlypartofFeoxidescanbereducedtoformFenanoparticles(NPs)availableforthegrowthofSWCNTs.ThepercentageofunreducedFeoxidesincreasedandtheyieldofSWCNTsdecreasedaccordinglywiththeincreaseofcatalystfeedingrateinDowner.SWCNTswerepreferentiallygrownonthecatalystsurfaceandinhibitedthesinteringoftheFecrystalliteswhichwouldbeformedthereafterinthedownstreamTFB,evidencedbyTEM,RamanandTGA.ThecoupledDowner-turbulentfluidized-bedreactortechnologyallowedhigherselectivityandhigherproductionrateofSWCNTsascomparedtoTFBalone.