壳聚糖作用下一步法合成具有高电活性的AgCl聚苯胺核壳结构

壳聚糖作用下一步法合成具有高电活性的AgCl聚苯胺核壳结构 壳聚糖作用下一步法合成具有高电活性的 AgCl聚苯胺核壳结构 第9期 2007年9月 无机化学 CH[INESEJ0URNAL0FINORG,ANICCHEMISlTRY Vo1.23No.9 Sep.,2007 壳聚糖作用下一步法合成具有高电活性的AgCI@聚苯胺核壳结构 冯晓叶青青侯文华朱俊杰 学化学化工学院.南京210093) 摘要:在壳聚糖的作用下,采用简单的一步法合成了具有星状结构的氯化银,聚苯胺核壳型复合材料.当壳聚糖的浓度为1% 时,所制备的氯化银,聚苯胺复合材料具有高度的分散性,壳层厚度为3O-80nm,核的直径在25,60nm范围内.通过透射电镜, 红外光谱和x一射线衍射对样品的形态和组成进行了 表 关于同志近三年现实表现材料材料类招标技术评分表图表与交易pdf视力表打印pdf用图表说话 pdf 征.循环伏安实验结果表明这种复合材料在中性条件下具有很好的电化 学活性. 关键词:氯化银;聚苯胺;核壳;电化学活性 中图分类号:0614,.122文献标识码:A文章编 号:1001—4861(2007)09.1572-.05 OneStepSynthesisofAgCl@PolyanilineCore-.shellNanostructure withEnhancedElectrochemicalActivityinthePresenceofChitosan FENGXiao--MiaoYEQing.-QingHOUWen--HuaZHUJun-Jie (SchoolofChemistryandChemicdEngtneering,NanjingUniversity,Nanjing210093) Abstract:Silverehloride@polyaniline(PAN[)core—shellcompositeswith astar-likestructureweresynthesized throughafacileone-.stepprocessinthepresenceofchitosan..Whenthechitosanconcentrationwasl%.highly dispersedAgCI@PANIcore—shellnanostructurewithashellthicknessof30-80nmandacorediameterof25-60 nmcouldbeobtained.Themorphologyandcompositionwerecharacterizedbytransmissionelectronmicroscopy (TEM), thatthi Fouriertransforminfrared(FT[R)andX-.raydiffraction(XRD).Cychcvohammetrieexperimentsindicated SkindofmaterialshowedexcellentelectrochemicalactivityinneutralpHenvironment. Keywords:silverchloride;polyaniline;core—shen;electrochemicalactivit y 0Introduction Thesynthesisofmaterialswithcontrolledsizeand morphologyisanimportantfactorfordefining propertiessuchastheelectronicbandgap,conductivity andlightemissionefficiency”.Three-?dimensional(3D) nanomaterialswithcore—shellstructure.locatedinthe transitionregionbetweenatomsandbulksolids,are interestinginthefieldsofcatalysis,biosensor.,and light-.emittingdevicesbecauseoftheirlargeBET surfacearea.particlesizeandquantumeffect,t. Conductingpolymer/inorganicnanocomposites withdifferentcombinationsofthetwocomponentshave attractedmoreandmoreattention.,sincetheyhave interestingphysicalpropertiesandmanypotential applicationsi31,.Asoneofthemostimportantconducting polymers,polyaniline(PANF)hasbeenintensively studiedinrecentyears.Thisismainlybecauseithas manyadvantagessuchaseasysynthesisandgood environmentalstabilityaswellaselectronic,biological, 收稿日期:2007—05..08.收修改稿日期:2007-0Z-06. 国家自然科学基金资助项目(No.20635020,90606016);国家基础研究 项~t(No.20o3CB6l58O4);南京大学 分析 定性数据统计分析pdf销售业绩分析模板建筑结构震害分析销售进度分析表京东商城竞争战略分析 测试基金. 通讯联系 人.E-.mail:jjzhu@nju.edu.cn;whou@nju.edu.cn;Tel&Fax:025_8359 4976 g-Cg~:冯晓苗,女,29岁,博士研究生;研究方向:复合材料与电化学. 第9期冯晓苗等:壳聚糖作用下一步法合成具有高电活性的AgCI@ 聚苯胺核壳结构1573 andopticalproperties【4.Thefabricationofnanocomp— ositescontainingPANIandalargevarietyofinorganic nanoparticleswithcore—shellstructurehavebeen reportedt. However,PANIisredox—activeonlyatacidic conditions,generallyatpH<4【”,thisgreatlyrestrictsits applicationsinbioelectrochemistry,whichnormally needsaneutralpHenvironment.Manyeffectiveefforts havebeendirectedtowardsenhancingtheredox—active ofPANIeitherbyintroducingacidicgroupsintothe PANIchainsordopingPAN1withnegativelycharged polyelectrolytesI王l31.Someofthesematerialshavebeen successfullyusedtoimmobilizeenzymest41. WesynthesizedAgCI@PANInanocompositeswith core—shellstructureinthepresenceofchitosaninthis work.Herein,chitosanasananchoragentpromoteda stronginteractionbetweenAgCIparticlesandaniline monomer,leadingtotheformationofAgCI@PANIcore— shellstructure.Themorphologyandcompositionwere characterizedbytransmissionelectronmicroscopy (TEM),Fouriertransforminfrared(n’IR)andX—ray diffraction(XRD).Cyclic indicatedthatthiskindof electrochemicalactivity. 1Experimental vohammetricexperiments materialshowedexcellent 1.1Materials Aniline,silvernitrate(AgNO3),hydrochloricacid (HCI)andammoniumpersulfate((NH4)2S2Os,APS)were purchasedfromShanghaiChemicalReagentCo.The deacetylationdegreeofchitosan(NantongShuanglin BiologicalProductInc.)wasabout95%.Anilinewas distilledunderreducedpressureandotherreagents wereusedasreceivedwithoutfurthertreatment. 1.2SynthesisofAgCI@PANICOl’e-shell composites AgNO3(0.01andaniline(0.05mmo1)were addedto20mLofchitosanaceticacidsolution.5mLof 1mo卜L一HClaqueoussolutionofAPSasoxidantwas addeddropwiseintotheabovemixtureunderstirringat roomtemperature.Themolarratiooterization Thecore—shellstructureofAgCI@PAN1was verifiedbytransmissionelectronmicroscopy(TEM, JEOLJEM一200CX).PowderX—raydiffractionpatterns fXRD1weretakenonaPhilip—XPertX—raydiffra— ctometerwithaCuKaX—ray Fourier—transforminfrared source(A=0.15418nm). (FTIR)spectroscopymen— surementswereperformedonBrukerFouriertransforln spectrometermodelVECTOR22usingKBrpellets. Electrochemicalexperimentswereconductedwitha CHI660Bworkstation(ShanghaiChenhua,Shanghai)in athree—electrodesystem.Allelectrochemicalexperi— mentswereperformedinacellcontaining20.0mLof phosphatebuffersolution(PBS,0.1mol?L)atroom temperatureandusingacoiledplatinumwireasthe auxiliaryelectrode,asaturatedcalomelelectrode(SCE) asthereferenceelectrode,andtheAgCI@PANImodi— fiedglassycarbonelectrode(GCE)astheworkingelect— rode. 2Resultsanddiscussion Chitosanwithexcellentbiodegradability,biocom— patibility,andnontoxicityisanN-deacetylatedderi— vativepolyelectrolyteofchitinandthesecond—most abundantnaturalpolysaccharideaftercellulose【一.In themolecularstructure(Scheme1)ofchitosan,the hydroxylandaminogroupsareregularlyarrangedatthe equatorialpositionsintheN1,4)一linkedD—glucosamine repeatingunits.Itcanactasastabilizertopromotethe interactionbetweeninorganicmaterialsandPANI. 瞬t)H嘴[--OHH +HH Hc0cH Scheme1Chemicalstructureofchitosan AgCI@PANIcore—shellnanocompositeswere synthesizedthroughafacileone—stepprocessinthe presenceofchitosan.Thecore—shellstructurecanbe confirmedbyTEMasshowninFig.1.Thedarkspots insidethenanoparticlescorrespondtoAgClthatis 1574无机化学第23卷 Fig.DistheTEMimagewithhighmagnificationof(C) Othersynthesisconditions:AgNO3O.O1anilineO.05mraol;n~:nxe=1:1;re actiontime24h Fig.1TEMimagesofAgCI@PANIcore?shell chitosan:(A)0.2%;(B)0.5%;(C)and nanocompositessynthesizedindifferentconcentrationsof (D)1% surroundedbyalayerofPANImatrix.Whenthe chitosanconcentrationswere0.2%and0.5%.the obtainedAgC1@PANInanocompositewithadiameter intherangeof40—120nmwasconglomerated.When thechitosanconcentrationincreasedfrom0.5%to1%. highlydispersedAgCl@PANIcore—shellnanostructure withashellthicknessof3080nmandacorediameter of25,60nmcouldbeobtained.Itshouldbenotedthat mostoftheas??preparednanocompositeshadastar??like structure.Duringtheprocessfortheformationof AgCl@PANIcore—shellnanoparticles,afterHC1aqu— eoussolutionofammoniumpersulfatewasaddeddro— pwisetochitosansolutioncontainingAgNO3and aniline,awhiteAgC1precipitateappearedimmediately andgraduallyturnedblue.Intheexperiment,chitosan asananchoragentplaysanimportantrole.Without shellstructurecouldnotbeformed. chitosan,thecore— Chitosanisausefulstabilizerthatcanpromoteastrong interactionbetweenAgC1particlesandaniline monomer.Forexample,ithasbeenusedsuccessfullyin thepreparationofuniformAgC1/polypyrrolecore—shell particles『l8】. TheXRDpatterncon~rnlsthepresenceofAgC1 nanoparticlesinthecomposites,asshowninFig.2.The broaddiffractionpeakappearedat20valueof25.is ascribedtotheperiodicityparalleltothepolymer chainsofPANI【例.Anothereightdiffractionpeaksabove 25.(20)correspondtoBraggsdeflectionsfrom(111), (200),(220),(311),(222),(400),(331),and(420)planes ofAgC1.Theyareingoodagreementwiththereported data(PDFNo.06一O480),showingtheexistenceofAgC1 nanoparticlesintheAgCI@PANIcore—shellcomposites. TheFTIRspectrumoftheAgCI@PANIisshown inFig.3.Thecharacteristicpeaksat1561am一and1 489am一correspondtotheC:Cstretchingofquinoid andbenzenoidrings,1301am一and1241am,are 第9期冯晓苗等:壳聚糖作用下一步法合成具有高电活性的AgCl@ 聚苯胺核壳结构1575 relatedtotheC—NandC=Nstretchingmodest2”.1142 em,isassignedtothein—planebendingofC—H.and 816emisattributedtotheout—of-planebendingofC— Hg.2XRDpatternofAgCl@PANIcole-shellnanocomposite Wavenumber,cm.. Synthesisconditions:AgNOs0.01g;aniline0.05retool;/IAn;/IAI~= 1:1:chitosanconcentration1%:reactiontime24h Fig.3VlqRsprectrumofAgCI@PANIcole—shell nanocomposite ThebareGCEwastestedbycyclicvoltammetric (CV)indifferentpHvaluesofphosphatebuffer solutions(PBS)beforeitwasdrop—coatedby AgCl@PANIcomposite.Itpresentsnoredoxprocessin thepotentialrangestudied.Theworkingelectrode coatedwiththecompos~ewasimmersedinthe electrolytesolutionfor30minpriortothemeasurement toassurediffusionofthesolutionintotheinterlayer spaceandpermitabetterionicexchange.Fig.4Ve thecyclicvoltammogramsofAgCI@PANImodified GCEmeasuredindifferentpHPBSatascanrateof 100mV?s,. 丘/v Synthesisconditions:AgNOs0.01g;aniline0.05retool;//,An: l:1;chitosanconcentration1%;reactiontime24h Fig.4CyclicvoltammogramsofAgCI@PANIcore—shell nanocomposltemodifiedGCEmeasuredin differentPBSpHbuffersatascanrateof100 mV.s’1 PANIshowstwoseparateredoxpeaksatpHvalue of1PBS.However,thesetworedoxpeaksmovecloser asthepHvalueofthesolutionisincreased.andfinally theymergetoshowonlyonebroadredoxpeakwhenthe pHvalueis4.ItiswellknownthatPANIexistsinthree well—definedoxidationstates:leucoemeraldine. emeraldineandpernigraniline.Intheleucoemeraldine stateallthenitrogenatomsareamines,butin pernigranilinethenitrogenatomsareimines.The amine/imineratioinemeraldineis,1.Furthermore. emeraldinecanbeinitsbaseorsaltform,dependingon thepHvalue.Thefirstoxidationwaveisassignedtothe transitionofleucoemeraldinetoemeraldinesaltandthe secondoxidationwaveisduetothetransitionfrom emeraldinesalttopernigranilinestate.Thebroad redoxpeakisobservedatpHvalueof4inPBSforthe samplewiththeredoxpotentialaround0.2V.This redoxpeakistheoverlapoftworedoxprocesses normallyfoundforthePANIsysteminacidic conditionstz~,asconfirmedbytheredoxbehaviorofthe compositesmeasuredindifferentPBSpHvalues.This electrochemicalbehaviorofAgC1/PANIisalsosimilar tothatofPANI/earbonnanotubemuhilayerfilms preparedbythelayer-by—layermethodt~. IntheCVcurves,itisclearthattheAgC1/PANI core—shellcompositesshowgoodredoxactivitynotonly 1576无机化学第23卷 atacidicsolutionbutalsoatneutralpHenvironmentin PBS.Itiswellknownthatsilverhalidesareonetypeof importantsemiconductors.AlthoughAgCIparticlesdo notmakeacontinuouselectronpath,theincorporated conductingAgCIprovidesmoreactivesitesforthe chargetransferthroughtheinterfaceinsidethe electrodebymakinggoodcontactswiththePANI matrix.Therefore,PANIparticleslocatedfarfromthe electrodesurfacecaneffectivelytakepartintheredox reaction.Meanwhile,webelievethatmorestudiesare neededtoinvestigatetheexactmechanismforthe enhancementinelectroactivity.TheAgCI@PANIcore— shellcompositeswithgoodelectrochemicalactivity havethepotentialapplicationintheareaofbiosensor. 3Conclusion Wehavedemonstratedtheone—stepsynthesisof AgCI@PANIcore—shellnanostructuresinthepresence ofchitosan.Chitosanasausefulanchoragentpromotea stronginteractionbetweenAgCIparticlesandaniline monomerleadingtotheformationofAgCI@PANIcore— shellstructure.Thecore—shellstructurewas characterizedbyTEM,XRD,FTIRandCV.IntheCV measurements.itwasfoundthattheAgCI@PANI nanocompositesshowedonewell—definedpairofredox peaksinneutralpHenvironment. 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