北京大学电分析课件电分析化学新技术elec.ppt

NovelTechniquesinElectroanalyticalChemistry电分析化学新技术YuanhuaShao 邵元华 教授Ph D CollegeofChemistryandMolecularEngineeringPekingUniversity Outline 1 Ultramicroelectrode microelectrode 超微电极或微电极 2 Electroanalyticalchemistryatliquid liquidinterfaces 液 液界面电分析化学 3 Scanningprobemicroscopy 扫描探针显微术 4 Spectroscopictechniques 光谱或波谱技术 5 Nano electrochemistry 纳米电化学 GeneralBooks 1 A J BardandL R Faulkner Electrochemicalmethods fundamentalsandapplications Wiley NewYork 1980 2ndEdition 2001 2 C M A BrettandA M O Brett Electrochemistry Principles Methods andApplications Oxford 19933 SouthamptonElectrochemistryGroup NewInstrumentalMethodsinElectrochemistry EllisHorwood Chichester 19854A M Bond ModernpolarographicmethodsinAnalyticalChemistry Dekker NewYork 19805J Koryta PrinciplesofElectrochemistry Wiley 19876P Delahay NewInstrumentalmethodsinElectrochemistry 19547R N Adams Electrochemistryatsolidelectrodes 19698 J O M BockrisandA N Reddy ModernElectrochemistry Plenum NewYork 19709电化学基础 张祖训 汪尔康 200010生命科学中的电分析化学 彭图治 杨丽菊编著 199911 电极过程动力学导论 查全性 1976 19872ndEdition 12电化学研究方法 田昭武 198413 电化学测定方法 腾岛昭等著 陈震等译 199514电分析化学 蒲国刚 袁倬斌 吴守国编著 199315超微电极电化学 张祖训 1998 Series1 ElectroanalyticalChemistry ed A J Bard2 ModernAspectsofElectrochemistry eds J O M Bockris B E Conway etal JournalsNature Science JACS Angew Chem IntEditAnal Chem May1 2000 J Phys Chem B J Electroanal Chem ElectrochimicaActa J Electrochem Society Electroanalysis ElectrochemicalandSolidStateLetters J AppliedElectrochemistry ElectrochemistryCommunications J SolidStateElectrochemistry Reviews AccountsofChemicalResearchAnalyticalChemistryAnnualReviewsofPhysicalChemistryChemicalReviewsWebsites http electrochem cwru edu estir PartOne 第一部分 1 Ultramicroelectrodes UMEs microelectrodes 超微电极或微电极 1 1Introduction1 2Definition1 3BriefHistory1 4Theoryandapplications 1 1Introduction 导言 电分析化学在60年代末期基本上停止不前 极谱学的研究已经达到其最高峰 随着其它分析化学技术的发展 极谱学越来越不重要 光谱电化学及微电极的出现重新使电化学及电分析化学获得新生 M Fleischmann A Bewicketal 1970sto1980s insitu光谱 波谱电化学M Fleischmann M Wightmanetal ultramicroelectrodes1970s 1980s 1 2Definition MicroelectrodesorultramicroelectrodesaredefinedasElectrodeswhichhaveatleastonedimensionthatisafunctionofitssize whichinpracticemeansbetween0 1and50 m WedefineaUMEoperationallyasanelectrodehavingatleastonedimension suchastheradiusofadiskortheWidthofaband smallerthan25 m Thisaspectiscalledthecriticaldimension Nano electrodes 1 1000nm m mm m nm 100 10 3 10 6 10 9 1 2Definition Commongeometriesincludespherical hemispherical disc ring andline 1 2Definition Commongeometriesincludespherical hemispherical disk ring andline MostcommonisthediskUME whichcanbefabricatedbysealingafinewireinaninsulator suchasglassoraplasticresin andthenexposingandPolishingacross sectionofthewire SphericalUMEscanbemadeforgold butaredifficulttorealizeforothermaterials HemisphericalUMEscanbeachievedbyplatingmercuryontoamicroelectrodedisk QuitedifferentisthebandUME whichhasasitscriticaldimensionawidth w intherangebelow25 m Thelength L canbemuchlarger eveninthecentimeterrange CylindricalUMEetc 1 3Briefhistory Inthelate1970s M Fleischmannetal atSouthamptonUniversityofU K andM Wightmanetal atIndianaUniversityofUSAstartedtoworkwithverysmallelectrodes 1 4Theoryandapplications Responsestoalarge AmplitudePotentialStep DiskUME ThediffusionequationforspeciesOiswrittenasfollowsforthisgeometry Whererdescribesradialpositionnormaltotheaxisofsymmetryatr 0 andzdescribeslineardisplacementnormaltotheplaneoftheelectrodeatz 0 Fiveboundaryconditionsareneededforasolution Threecomefromtheinitialconditionandtwosemi infiniteconditions AokiandOsteryoungaddresseditintermsofadimensionlessParameter representingthesquaredratioofthediffusionlengthtotheradiusofthedisk 电流 时间曲线是 当较短时间时 1 当较长时间时 1 从上述几个公式可知 当 很大时 微园盘电极的稳态电流为 SummaryofBehavioratUltramicroelectrodes AlthoughtherearesomeimportantdifferencesinthebehaviorofUMEswithdifferentshapes itisusefulheretorecollectsomecommonfeaturesintheresponsestoalarge amplitudepotentialStep First atshorttime wherethediffusion layerthicknessissmallcomparedtothecriticaldimension thecurrentatanyUMEfollowstheCottrellequation andsemi infinitelineardiffusionapplies Second atlongtimes wherethediffusion layerthicknessislargecomparedtothecriticaldimension thecurrentatanyUMEapproachesasteadystateoraquasi steadystate Onecanwritethecurrentinthislimitasfollowing 对于最简单的情况 球形电极的情况 其电流 时间的关系是 Earlytransientregimeortheregimeofsemi infinitelineardiffusion Long timelimitSteady stateregime UMEshaveextendedelectrochemicalmethodologyintobroadnewdomainsofspace time chemicalmedium andmethodology Applications Kineticmeasurements Steady statevoltammogramsatasphericalorhemisphericalelectrodeforavariouskineticregimes 最常用的采用稳态伏安法获取动力学数据的方法 MethodofMirkinandBard2 Curvefitting size BiologicalSystem ORGANISM TISSUESCELLS AMINOACIDSH2O CO2 PROTEINSPOLYPEPIDE MEMBRANEENZYME 半径 A 91 B 27 C 1 8nm Anal chem 2001 73 5346 5351 TheSEMdiagramsofNano andMicropipettes Micropipettes Nanopipettes 我们group可以制备内径从几个nm到十几个 m的玻璃纳 微