北京大學電分析課件電分析化學新技術(shù)elec.ppt

NovelTechniquesinElectroanalyticalChemistry電分析化學新技術(shù)YuanhuaShao 邵元華 教授Ph D CollegeofChemistryandMolecularEngineeringPekingUniversity Outline 1 Ultramicroelectrode microelectrode 超微電極或微電極 2 Electroanalyticalchemistryatliquid liquidinterfaces 液 液界面電分析化學 3 Scanningprobemicroscopy 掃描探針顯微術(shù) 4 Spectroscopictechniques 光譜或波譜技術(shù) 5 Nano electrochemistry 納米電化學 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電化學基礎(chǔ) 張祖訓 汪爾康 200010生命科學中的電分析化學 彭圖治 楊麗菊編著 199911 電極過程動力學導論 查全性 1976 19872ndEdition 12電化學研究方法 田昭武 198413 電化學測定方法 騰島昭等著 陳震等譯 199514電分析化學 蒲國剛 袁倬斌 吳守國編著 199315超微電極電化學 張祖訓 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 超微電極或微電極 1 1Introduction1 2Definition1 3BriefHistory1 4Theoryandapplications 1 1Introduction 導言 電分析化學在60年代末期基本上停止不前 極譜學的研究已經(jīng)達到其最高峰 隨著其它分析化學技術(shù)的發(fā)展 極譜學越來越不重要 光譜電化學及微電極的出現(xiàn)重新使電化學及電分析化學獲得新生 M Fleischmann A Bewicketal 1970sto1980s insitu光譜 波譜電化學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 電流 時間曲線是 當較短時間時 1 當較長時間時 1 從上述幾個公式可知 當 很大時 微園盤電極的穩(wěn)態(tài)電流為 SummaryofBehavioratUltramicroelectrodes AlthoughtherearesomeimportantdifferencesinthebehaviorofUMEswithdifferentshapes itisusefulheretorecollectsomecommonfeaturesintheresponsestoalarge amplitudepotentialStep First atshorttime wherethediffusion layerthicknessissmallcomparedtothecriticaldimension thecurrentatanyUMEfollowstheCottrellequation andsemi infinitelineardiffusionapplies Second atlongtimes wherethediffusion layerthicknessislargecomparedtothecriticaldimension thecurrentatanyUMEapproachesasteadystateoraquasi steadystate Onecanwritethecurrentinthislimitasfollowing 對于最簡單的情況 球形電極的情況 其電流 時間的關(guān)系是 Earlytransientregimeortheregimeofsemi infinitelineardiffusion Long timelimitSteady stateregime UMEshaveextendedelectrochemicalmethodologyintobroadnewdomainsofspace time chemicalmedium andmethodology Applications Kineticmeasurements Steady statevoltammogramsatasphericalorhemisphericalelectrodeforavariouskineticregimes 最常用的采用穩(wěn)態(tài)伏安法獲取動力學數(shù)據(jù)的方法 MethodofMirkinandBard2 Curvefitting size BiologicalSystem ORGANISM TISSUESCELLS AMINOACIDSH2O CO2 PROTEINSPOLYPEPIDE MEMBRANEENZYME 半徑 A 91 B 27 C 1 8nm Anal chem 2001 73 5346 5351 TheSEMdiagramsofNano andMicropipettes Micropipettes Nanopipettes 我們group可以制備內(nèi)徑從幾個nm到十幾個 m的玻璃納 微