Hydrothermal synthesis and characterization of coreshell ALO

MicroporousandMesoporousMaterials119(2009)

208–216

ContentslistsavailableatScienceDirect

MicroporousandMesoporousMaterials

journalhomepage:http://doc.guandang.net/locate/micromes

o

Hydrothermalsynthesisandcharacterizationofcore/shellALOOHmicrospheres

LiangmiaoZhang,WencongLu*,LiumingYan,YongliFeng,XinhuaBao,JipengNi,XingfuShang,YongLv

DepartmentofChemistry,ShanghaiUniversity,Shanghai200444,PRChina

StateKeyLaboratoryofPowdermetallurgy,CentralSouthUniversity,Changsha410083,PRChina

articleinfoabstract

TheAlOOHcore/shellmicrospheresweresuccessfullysynthesizedviaaone-steptemplate-freehydro-thermalroute.Bysimplychangingtheratioofalcoholtowater,core/shellmicrospheresconstructedwithnanoplateletsandtheircurlingstructurescouldbeselectivelysynthesized.Aseriesofcontrolledexper-imentshavealsobeencarriedouttobetterunderstandtheformationmechanismofAlOOHspheresandthefunctionofreactantsusedintheexperiments.Theformationofcore/shellstructuresmayinvolveaggregationofamorphousbuildingclustersintospheresandtheirsubsequentreaction,dissolution,andre-depositionprocess.Themorphology,structure,andcompositionofthespheresareinvestigatedusing eld-emissionscanningelectronmicroscopy,transmissionelectronmicroscopy,andX-raydiffrac-tionanalysis.Thespeci csurfaceareaandpore-sizedistributionoftheobtainedproductasdeterminedbygas-sorptionmeasurementsshowthattheboehmitecore–shellmicrospheresexhibithighBrunauer–Emmett–Teller(BET)surfaceareaandporosityproperties.Theas-preparedAlOOHcore–shellsuperstruc-turesarepowerfulintheremovalofCongoredpollutantfromwastewater.

Ó2008ElsevierInc.Allrightsreserved.

Articlehistory:

Received8July2008

Receivedinrevisedform14October2008Accepted20October2008

Availableonline30October2008Keywords:AlOOH

Core/shellmicrospheresHydrothermalmethodWatertreatment

1.Introduction

Thefabricationofhighlyorderedmicro-andnanostructureshasattractedmuchinterestinareasofmaterialsscience[1].Inpartic-ular,thefabricationofhierarchicalandcomplexnano-andmicro-structuresassembledusingnanoparticles,nanorods,nanoribbons,andsoforth,asbuildingblocksatdifferentlevels,hasbecomere-centlyahottopicinmaterialresearch elds[2].Core/shellandhol-lowspheres,astwospecialkindsof3Dcurvedmicrostructureswithinnercavities,areofgreatinterestforalargespectrumofapplications,suchasadsorbents[3],deliverycarriers[4],catalysts[5],gassensors[6],chemicalreactors[7],controlreleaseofvarioussubstances[8],andprotectionofenvironmentallysensitivebiolog-icalmolecules[9].Uptonow,variouskindsofmetaloxide[10],sul de[11],andhydrate[12]withcore/shellandhollowmicro-structureshavebeensuccessfullysynthesized.ForthecaseofTiO2,theuniquecore/shellstructureshowsdramaticactivityenhancementinphotocatalyticphenoldegradation[13].Sincetheutilityorpropertyofnano-andmicrostructureisinextricablylinkedtoitsshapeandsize[14],itisameaningfulworktodesignandfabricatedifferentkindsofnanoandmicrostructuresbyusingappropriatenanoscalebuildingblocksandvoidspace.However,itstillremainsamajorchallengetodevelopafacile,template-free,

*Correspondingauthor.Address:DepartmentofChemistry,ShanghaiUniversity,Shanghai200444,PRChina.Tel.:+862166133513;fax:+862166133522.

E-mailaddress:lmzhang@http://doc.guandang.net(W.Lu).1387-1811/$-seefrontmatterÓ2008ElsevierInc.Allrightsreserved.doi:10.1016/j.micromeso.2008.10.017

one-stepsolutionrouteforthepreparationofinorganiccore/shellandhollowmicrostructures.

Aluminaisoneofthemostimportantoxidesandhasbeenstud-iedintensivelyoveralongperiodoftimebecauseofitsbroadapplicationsinadsorbents,compositematerials,ceramics,cata-lystsandcatalystsupports[15].Thesynthesisofnanostructuredaluminahasreceivedconsiderableinterestduetotheirpromisingproperties,suchashighelasticmodulus,thermalandchemicalsta-bility,andopticalcharacteristics.Thealuminacanbeobtainedthroughthedehydrationoftheboehmite,andtheoriginalsizeandthemorphologyoftheboehmitenanostructurescanbere-tained.Uptonow,manykindsofinterestinganddelicateboehmitenanostructures,suchasnanoribbons[16],nano bers[17,18],nanobelts[19],nanotubes[20],bundlesofalignedboehmitenano-wires[21],and ower-like3Dnanoarchitectures[22]havebeenprepared.Morerecently,wehavedevelopedafacilehydrothermalsyntheticstrategyforselectivelypreparinghierarchicalcanta-loupe-likeAlOOHsuperstructuresbasedonself-assemblyof1Dnanorods[23].AlOOHself-encapsulatedstructureshavebeensyn-thesizedsuccessfullybyhydrothermalmethodinthepresenceofPS-b-PHEAamphiphilicblockcopolymerasthestructure-directingreagent[24a].Panetal.reportedthepreparationofAl2O3hollowshellsviathecalcinationsofAl/AlOOHÁnH2Ocore–shellparticles,althoughAlcoexistedwithAlOOH[24b,c].However,itstillremainsasigni cantchallengetodevelopfacile,mild,template-freeandshape-controllableroutefortheformationofpureAlOOHcore/shellandhollowmicrostructures.Inthispaper,wereportatem-plate-freehydrothermalroutetofabricateAlOOHcore/shell

L.Zhangetal./MicroporousandMesoporousMaterials119(2009)208–216209

microspheresviaasurfacereaction-dissolution-recrystallizationprocess.Judiciouschoiceofthealcoholamountsandreactiontimeaffordsthesynthesisofsphereswithadjustablemorphologyandinteriorstructurethatistunablefromsolidtosphere-in-sphere.2.Experimentalsection2.1.Preparation

AlOOHwithcore/shellmicroarchitecturewerepreparedusingthehydrothermalmethodinamixedethanol–watersolution.Inatypicalprocedure,2mmolofAl(NO3)3Á9H2Owasdissolvedin20mLdistilledwateratroomtemperatureformingahomoge-neoussolution.Andthen,another20mLabsoluteethanolwasaddedslowly.Inaddition,0.5mmoltrisodiumcitratedehydrate(C6H5Na3O7Á2H2O)wasadded,andtheresultingsolutionwasfur-therstirredvigorouslyfor30min.TheresultedclearandcolorlesssolutionwastransferredintoaTe on-linedstainlessautoclave ll-ing80%ofthetotalvolume.Theautoclavewassealedandmain-tainedat200°Cfor24h.Theautoclavewasthencooledtoroomtemperaturenaturally.Thisprocedureresultedinawhitepowderprecipitated.Finally,thewhitepo …… 此处隐藏：24762字，全部文档内容请下载后查看。喜欢就下载吧 ……