北京大学电分析液液界面电化学及电分析化学简介elect7课件

液/液界面电化学及电 分析化学简介邵元华,教授CollegeofChemistryandMolecularEngineering PekingUniversity二00二年十一月1.液/液界面电化学的发展历史2.液/液界面电化学的基本原理3.液/液界面电化学的主要研究方法及仪器设备4.液/液界面电化学的现状5.液/液界面电化学的未来展望主要内容参考书和文献：1.液/液界面电化学，P.Vanysek著，罗颖华译，汪尔康审校，吉林大学出版社，1987年2.H.H.GiraultandD.J.Schiffrin,inElectroanalyticalChemistry,A.J.Bard.,Ed.;Vol:15,p.1,MarcelDekker,NewYork,19893.H.H.Girault,inModernAspectsofElectrochemistry,J.O.Bockris,B.E.Conway,R.E.White,Eds.;PlenumPress,NewYork,1993,Vol:25,p.14.J.Koryta,Electrochemicalpolarizationphenomenaattheinterfaceoftwoimmiscibleelectrolytesolutions.ElectrochimicaActa,24(1979)293-3005.J.Koryta,Electrochemicalpolarizationphenomenaattheinterfaceoftwoimmiscibleelectrolytesolutions.II.Progresssince1978.ElectrochimicaActa,29(1984)445-4526.VolkovAG,DeamerDW.Liquid-liquidinterfaces.TheoryandMethods.California:CRCPress,1996.Briefhistory: 1902,NernstandRiesenfeld1906,Cremerpointedoutthattheanalogybetweenthewater/oil/waterconcentrationcellsandbiologicalmembrane1939,VerweyandNiessen,firsttheoreticalpaperontheelectricaldoublelayerandpotentialdistributionatITIES1970s,Gavachetal.inFrance首先认识到L/L界面在一定的实验条件下可以被极化，并用Chronopotentiometry对一些简单离子在Water/Nitrobenzene(W/NB)的转移行为进行了研究。同时用ModifiedVerwey-Niessen(MVN)对实验结果进行了分析。随后Korytaetal.发展了滴水电极及相应的实验装置，并首先研究了中性载体加速离子转移反应。Samecetal.in1979设计了具有iR降补偿性质的四电极恒电位仪，用来记录离子转移反应的伏安图。这样L/L界面电化学才在世界各地得到普及和蓬勃发展。1980s,汪尔康先生等是中国第一个从事L/L界面电化学研究的group1986,Giraultetal.第一个将微-L/L界面支持在Micropipettes上 1991,Cornetal.应用SHG研究L/L界面 1995，MirkinandBardetal.应用SECM研究L/L界面1997,Y.Shaoetal.第一个将纳米级-L/L界面支持在Nanopipettes上最近几年各种光谱技术也应用于此领域的研究WWElectrodeOilGold，Pt，CNB1,2-DCEThedifferencebetweenL/Linterfaceand Electrode/ElectrolyteinterfaceChemicalsensorsElectrochemistryH+，pHK+,Na+,NH4+Cl-,Ac+O+e=RElectroactivespeciesNonelectroactivespeciesL/LInterfaceElectrochemistryatL/LInterfacesisthebridgebetweentheconventionalelectrochemistryandChemicalsensorsElectrochemistryatLiquid/LiquidInterfacesisafastwaytoselectreceptorsformakingchemicalsensorsElectrodeOBiologicalMembraneModelL/LInterfaceElectrode/electrolyte

Membrane/solutionArtificial,supportedmembraneandBLM2.液/液界面电化学的基本原理2.1.EquilibriumconditionsandNernstpotentialIngeneralatLiquid/Liquidinterfaces,therearetwotypesofchargepartition: (A)thetransferofanionMwiththechargenumberzfromthephasewtothephaseoandthereverse: MZ(w) =MZ(o)M+(w) +L(o) =ML+(o)(B)theelectrontransferbetweenaredoxcoupleO1/R1inthephasewandaredoxcoupleO2/R2inthephaseo,whichcanberepresentedas:O1(w)+R2(o)=R1(w)+O2(o)

NernstEquationsLiquid/Liquidinterfaceshavebeenclassifiedintotheideal-polarizedinterfaceandno-polarizedinterface.2.2.SingleionGibbsenergyoftransferTATBassumption2.3.SolvationofIonBornequation2.4.Interfacialstructureandtheiontransfermechanism(A)MVNMODEL(B)GSMODELAtpresent,themostcommonlyusedorganicsolventsarenitrobenzene(NB)and1,2-dichloroethane(1,2-DCE).Someothersolventshavebeentriedinthepasttwodecades,forexample,propiophenone,4-isopropyl-1-methyl-2-nitrobenzene,dichloro-methane,nitrotulene,chloroform,anilineetc.Inordertogetmoreflexiblechoice,organicsolventmixtureshavebeenalsoemployed,forexample,nitrobenzene+chlorobenzene,NB+benzonitrileandNB+benzene.Baseelectrolytes:TBATPB(tetrabutylammoniumtetraphenylborate),TBATPBCl,CVTPB,BTPPATPB(Bis[triphenylphosphoranylidene]ammoniumtetraphenylborate)2-电极系统新的技术，例如:SHG(Secondharmonicgeneration)microelectrodes,micropipettesandnano-pipettesSECMFemto-laserSimulationsThinfilms现已用在L/LInterfaces的研究。各种电化学方法和技术4.液/液界面电化学的现状Structure: MVNModelandGSModelMechanism: FacilitatediontransfermechanismKinetics: Butler-Volmerequation,Marcustheory Nanometeropipettes SECMApplications:

Thinfilms(solarcell,drugdelivery)目前国际上液/液界面电化学研究 存在的主要问题1.界面结构未知!MVN模型和混合溶剂层模型(GS)2.可供选择作为有机相的有机溶剂数目有限3.没有很好的获取转移反应动力学的实验手段4.iR(i-电流，R-电阻，iR降是由于溶液中电阻所引起的干扰)降及充电电流较常规电化学更加严重HowtosolvetheseProblemsMicroelectrodes:SolidandNano-andMicropipettes+ScanningElectrochemicalMicroscopy,SECMElectrochemistryatL/LInterfacesArtificialMembrane/ElectrolyteInterfacesBLMArtificialMembraneandBiosensorsModifiedL/LInterfacesMicroelectrodesNano-andMicropipettesSECMTheSEMdiagramsofNano-andMicropipettesMicropipettesNanopipettesMicropipettesTheta()MicropipetteTheSEMdiagramsofNano-andMicropipettesMicropipettesNanopipettes我们group可以制备内径从几个nm到十几个m的玻璃纳、微米管AqueousPhaseOrganicPhaseAqueousPhaseOrganicPhaseAsymmetricDiffusionFieldTBATPBassupportingelectrolyteinDCETBATPBClassupportingelectrolyteinDCEBTPPATPBassupportingelectrolyteinDCEMicropipetteasatooltodeterminetheionicspecieslimitingthepotentialwindowatL/LInterfacesTBATPB(Tetrabutyalammoniumtetraphenylborate)TBATPBCl(tetrabutyl-ammoniumtetrakis[4-chlorophenyl]borate)BTPPATPB(Bis[triphosphor-anylidene]ammoniumtetraphenyl-borate)1,2-dichloroethane(DCE)Ag/AgCl/0.01MTBACl/0.25mMDB18C6+0.01MTBATPBCl//0.01MKCl/AgCl/AgIdentifythedifferentmechanismsACTTOCTICTIDwowowowoIdentifyofdifferentmechanismsoffacilitatediontransfersIdisk=4nFaDCIpip=3.35nFaDCWhyIpipisabout2.63timesbiggerthanIdisk?Silanizationplaysveryimportantrolehere!Anal.Chem.,1998,70,p3155-31613.4E-9Nanometer-sizedL/LInterface纳米管NanopipetAqueousPhaseNano-ITIESkofrom0.1cm/sto10cm/sA54nmradiusB5nmradiusJ.Am.Chem.Soc.,1997,119,8103K+(w)+DB18C6(DCE)=[K+DB18C6](DCE)

J.Am.Chem.Soc.,1998,120,12700科学意义和创新点：第一次在实验上实现了非氧化还原物质的Generation/CollectionMode。对于测量反应中间产物和快速电荷转移反应动力学有重要意义。Thephotoof-micropipetteundermicroscope“Non-solution”L/LInterfaceElectrochemistryGenerator(1)andcollector(2)voltammogramsofthetransferofK+betweenwaterandDCEcontainingDB18C6igvs.Egandicvs.Egcurvesobtainedwithanaqueousfilmlinkingtwobarrelsofthe-pipetDetectionofammoniaintheair.Cyclicvoltammogamsobtainedwitha-pipetexposedtoair(1)andammoniavaporaboveits2MsolutionThepotentialwindowsdependupontheamountofAgar.Scanrateis30mV/s.Theradiusofthemicropipetteis4m，curves1、2、3and4correspondingto25%、10%、1%and0.5%ofAgar,respectivelyAgar-waterMicroelectrodeCyclicVoltammogramsofK+transferfacilitatedbyDB18C6.KClis0.1M，Scanrate=30mV/s。Theradiusofthemicropipetteis3μm。Curves1,2and3correspondingtotheconcentrationsofDB18C60.25,0.5and1.0mM.123(a)r=12µm(b