材料专业文献翻译.doc

材料专业文献翻译.doc

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SynthesisandGasSensitivityofIn2O3/CdOComposite

Abstract:

Indiumoxide（In2O3）wassynthesizedusingahydrothermalprocess.ThecrystallographyandmicrostructureofthesynthesizedsampleswerecharacterizedbyX-raydiffraction（XRD）,scanningelectronmicroscopy（SEM）,energydispersiveX-rayspectroscopy（EDX）,andtransmissionelectronmicroscopy（TEM）.TheIn2O3hadaflower-likehierarchicalnanostructureandwascomposedoftinynear-sphericalcrystalswithadiameterofapproximately20nm.WhenIn2O3wasmixedwithCdOina1:

1molarratio,itwasfoundthattheresultingIn2O3/CdOcompositeshowedaninterestinggrape-likeporousmicrostructurefollowingcalcinationsatelevatedtemperatures.AgassensorusingthisIn2O3/CdOcompositeasthesensingmaterialshowedhighersensitivitytodifferentconcentrationofformaldehydethanthegassensorbasedonpureflower-likeIn2O3nanomaterials.TheIn2O3/CdO-basedsensorsshowedahighsensitivitytoaconcentrationof0.05×10-6formaldehydeattheoptimizedoperatingtemperatureof410°Candagoodlevelofselectivityoverotherpossibleinterferencegasessuchasethanol,toluene,acetone,methanol,andammonia.ThegassensingmechanismofIn2O3/CdOsensorhasbeendiscussedindetail.

1Introduction

Formaldehyde（HCHO）isacolorlessandstrong-smellinggascomingfrombuildingmaterials,interiordecorationmaterials,woodfurniture,carpetandsoon.

HCHOisoneofthemostdangerousindoorpollutantsamongvolatileorganiccompounds（VOCs）,andisfoundtobeassociatedwithasthma,nasopharyngeal

cancer,andmultiplesubjectivehealthcomplaints.Inparticular,HCHOisconsideredasamajorcauseofsickbuildingsyndrome（SBS）.WorldHealthOrganization（WHO）establishedastandardof0.08×10-6（volumefraction）averagedover30minforlong-termexposureinformaldehydevapor.ManymethodstodetectVOCshavebeeninvestigated.Amongthem,semiconductorgassensorsarewidelyusedsincetheyarecheapandeasytobeavailable.Thesensingmaterials,includingSnO2,10-12ZnO,13NiO,14andIn2O3,15,16havebeenexploredforformaldehydedetection.

Inrecentyears,nanostructuresemiconductormaterialshavebeenextensivelystudiedduetotheirexceptionalpropertiesandpotentialapplicationsinvariousfields.Amongthem,indiumoxide（energygap3.67eV,Bohrradius2.14nm）materialhasbeenwidelystudiedbecauseofitsuniqueoptoelectronicproperties,suchashighelectricalconductivityandhighUVtransparency.Ithasbeenwidelyusedintheoptoelectronicdevicessuchassolarcells,windowheaters,andliquidcrystaldisplays。

Ithasbeenalsoexploredforsensingmaterialsfordetecting

O3，HCHO,trimethylamine（TMA）,NO2CO,andNH3。

Variousvapor-phaseorphysicaltemplatemethodsweredevelopedtoprepareIn2O3nanocrystals.Forexample,In2O3nanowiresweresynthesizedbyusingthevapor-liquid-solidtechnique。

TheIn2O3nanowirearraysornanorodswereinducedbytemplate-assistedgrowth,andtheIn2O3nanobeltswereobtainedthroughthermalevaporation。

Besidesthesephysicalmethods,therearealsowet-chemistrymethodstopreparespecificIn2O3nanostructures.Forinstance,In2O3withstructuresofnanorodbundles,spherelikeagglomerates,lotus-root-like,andnanotubesweresuccessfullysynthesizedbyhydrothermalroute。

Quasi-monodisperseIn2O3nanocrystalswereobtainedthroughanorganicsolutionsyntheticroute。

Inthiswork,theflower-likehierachicalnanostructureIn2O3composedofthetinysphericalnanocrystallineswasfabricatedbyusingthehydrothermalmethod.Then,theas-synthesizedIn2O3powdersweremixedwithCdOinamolarratioof1:

1toformagassensingmaterial.TheformaldehydesensingpropertiesoftheIn2O3/CdO-basedsensorswerecarriedout.

2Experimental

2.1Preparationandcharacterizationofmaterials

InCl3·4H2O（99.5%）wasobtainedfromSinopharmChemicalReagentCo.,Ltd.,China.Ethylenediaminetetraaceticacid（99.5%,EDTA,C10H16N2O8）andCS（NH2）2（99.0%）wereobtainedfromTianjinKermelChemicalReagentCo.,Ltd.,

China.CdO（99.5%）powderwasanalyticalgradewith30nmparticlesize,andpurchasedfromHaitaiNanometerMaterialsCo.,China.Allofthereagentsusedintheexperimentswereanalyticalgradeandutilizedwithoutfurtherpurification.

Flower-likeIn2O3wassynthesizedbyahydrothermalmethod.Inatypicalprocedure,1mmolInCl3·4H2Oand2mmolCS（NH2）2weredissolvedin30mLEDTA.Afewdropsofammoniaweredrippedintothesolution,andthesolutionwasundertheconditionsofultrasonicdispersingandconstantstirringalternatelyfor20min.Then,themixturewastransferredintoa50mLTeflon-linedstainlesssteelautoclave.Theautoclavewassealedandmaintainedinanelectricovenat180°Cfor18h.Afterthat,theautoclavewascooledtoroomtemperaturenaturally.Thepinkprecipitatewascollectedandwashedwithethanolanddeionizedwater