ScanningElectrochemicalMicroscopy扫描电化学显微镜扫描电化学显微镜学习总结张富纬2016.9.17Asmallprobeisscannedinshortdistanceoverasamplesurfaceandacharacteristicpropertyofthesampleisdetected.Interactionofprobeandsample!其原理是在样品短距离的表面上,通过探针与样品的相互作用并检测到样品的特征属性。扫描探针技术有STM,AFM,SNOM,SECMScanningelectrochemicalmicroscopy(SECM)istheonlytechniqueabletodetect(electro-)chemicalreactions.SECM是唯一一种能够检测(电)化学反应的扫描探针技术。Resolutiondependsonthetipsize!SECM–ClassificationSECM归类于扫描探针技术Scanningprobetechniques:3BasicSetup下图是整个仪器的形貌44这是与SECM连用的电化学工作站这是SECM的工作池也就是放样品的区域(长宽高大概为2*2*1cm)SECM目前只能在小样品(1cm左右),平面上做一些基础性研究使用。ImagingModes5SECM的这些工作模式基底都是不通电的,这是原来理解上的一个误区。这个误区在下面反馈模式中的正反馈中给本人和万通中国的人都造成了误解。正反馈是由于基底为导体由于导体与探针之间的相互作用导致了电流的增大。其关于电流密度的扫描是通过一定电镀时间的间隔下对被镀件表面进行扫描通过哪里沉积的多少来实现的。ImagingModes–NegativeFeedbackAreversibleredoxspeciesisrequired!6ImagingModes–PositiveFeedback7由于基底不通电所以检测基底活性是SECM都是采用的可溶解的氧化还原电对(如Fe3+/Fe2+)。FeedbackMode-MeasurementConditionsCalculatedapproachcurveswithRG=10accordingtoJ.L.Amphlettetal.,J.Phys.Chem.B102(1998),99468FeedbackMode9ArrayScanforSurfaceMappingxydatapointindividuallineofarrayscan10FeedbackModeVisualizationofelectrochemicalactivitydistributiononasamplesurface.11FeedbackMode-ExampleRu3+Ru2+itip-400mV12FeedbackMode-ExampleDifferencesinlocalelectrochemicalactivitye.g.duetosurfaceimpurities.GeneralgoalofSECMstudiesisthedeterminationoftheelectron-transferkineticsatthesamplesurface!13Generator/CollectorMode(GCMode)14Generator/CollectorMode-Example15ComparisonFeedbackandGCMode5mM[Ru(NH3)6]3-in100mMKCl,RE:Ag/AgCl(3MKCl),forGC:WE1:2ndbandEsample=-400mV,WE2:25µmPttipRu2+Ru3+0mVRu3+Ru2+Ru3+Ru2+-400mV16ComparisonFeedbackandGCMode5mM[Ru(NH3)6]3-in100mMKCl,RE:Ag/AgCl(3MKCl),forGC:WE1:2ndbandEsample=-400mV,WE2:25µmPttip+sensitivitylateralresolution(diffusionprofiles)timedependency+lateralresolutionhighbackgroundcurrentredoxmediatorrequired17PracticalTrainingSECM18Fe2+Fe3+500mVLocalexperimentsduetomobileelectrochemicalcellStandardEC(OCPdetection,polarizationcurvesetc.)possibleOnlysmallareaofsamplesisincontactwithelectrolyte,exchangeofsolutionpriortoeachnewgridpointRECEElectrolyteWE19对于我们公司这种大且形状复杂的产品,Thomas给出了一下Cell的解决方案不过这是一种全新的技术,其液滴口直径也不超过1mm,基本无工业化应用价值。ScanningDropletCell–SDCScanningDropletCell–OptionSDCLocalexperimentsduetomobileelectrochemicalcellStandardEC(OCPdetection,polarizationcurvesetc.)possibleOnlysmallareaofsamplesisincontactwithelectrolytePhotoelectrochemistryRECEElectrolyteinlet20SECM–ApplicationsSECM的应用领域ApplicationSECMisalwaysuseablewhenthelocaleffectsdeterminethepropertyofthewholematerial(globalappearance).SECM主要是通过研究材料的局部反应来判断材料的整体性能。2FieldsofApplication3腐蚀催化剂燃料电池表面修饰与我们公司关联性较大的主要就是腐蚀不过其主要是用于单层涂层的耐蚀性研究。对于电镀产品而言此功能通过电化学工作站的阻抗分析也可以实现。ReactivityonStainlessSteels304and316J.Izquierdoetal.,ElectrochimicaActa134(2014),167StainlessSteel316StainlessSteel3040.5h4h7.5h24h0.5h3h4Distributionofiron(II)ions0.25MHCl(GC-Mode)O2O2O2O2O2CorrosionofSteel–OxygenCompetitionE,iiTEConsumptionofOxygenistracedVariationofGC-modeJ.J.Santanaetal.,Electrochim.Acta55(2010),44885Corrosion–ProtectiveCoatingsR.G.Duarteetal.,Prog.Org.Coat.74(2012),365PVCPlastisolcoatednickelfoilsand0.5mMferrocene-methanol.InsulatorassamplesurfaceTopography6Corrosion–ProtectiveCoatingsJ.Izquierdoetal.,Prog.Org.Coat.74(2012),5262-mercaptobenzimidazoleSECMimagerecordedinmeasuringsolutionof0.1MNa2SO4+1mMferrocenemethanol7E.Martinez-Lombardiaetal.,Electrochim.Acta116(2014),895mMferrocenemethanolCorrosion-CopperImagewithpassivelayerEffectsduetocrystallographicorientationsofcopperImageafterremovalofpassivelayer8DissimilarWeldJ.Jayarajetal.,J.Adv.Microsc.Res.7(2012),214Tipreactionat1.5V:HNO3+2H++2e-→HNO2+H2O9Self-healingCoatingsA.Pilbáthetal.,Prog.Org.Coat.75(2012),480DetectionofFe2+DetectionofO2Microcapsuleswithlinseedoilmixedintoepoxyresincoating.10Catalysis11PtonCsupport(E-tek)VulcanXC-72RPrintexL6Catalysis–FuelCellsOxygenReductionReactionORRinalkalinesolution,effectofcarbonsupportH2O2detectionM.H.M.T.Assumpçãoetal.,Carbon49(2011),284212ElectrocatalyticActivityofCarbonFiberInvestigationofasinglestrandofcarbonfiber.3mMα-methylferrocenemethanolinphosphatebufferPseudofirstorderrateconstantviaapproachcurvesV.S.Joshietal.,J.Phys.Chem.C116(2012),970313MembraneTransportTransportphenomenainchannels/membranes/pores14DiffusionthroughMembranesforGasSensorsM.Nebeletal.,Electrochim.Acta55(2010),792315LifeSciences-BiodegradableMaterialM.D.Peredaetal.,ActaBiomater.6(2010),177216MaterialScience–ReducedGrapheneOxideonFabricsJ.Molinaetal.,Appl.Surf.Sci.279(2013),4617BiosensorsBiosensorcharacterization18GCandRC-SECMforBiosensorsI.Morkvenaite-Vilkoncieneetal.,RSCAdv.4(2014),50064.19CellularActivityReleaseorconsumption20RespirationActivityd,t=15msTopographyM.Nebeletal.Angew.Chem.Int.Ed.52(2013)633521Intra-andExtracellularRedoxProcesses–YeastCellI.Morkvenaite-Vilkoncieneetal.,SensorsandActuatorsB:Chemical228(2016),20022SECM–AdvancedDetectionModesSECM–前沿的检测方法AC-SECM阻抗-SECM联用技术AlladvantagesoffrequencydependentresponseNoredoxmediatornecessaryDilutedsolutionpossibleImpedancespectraat