扫描电化学显微镜瑞士万通学习报告课件

1、Scanning Electrochemical Microscopy扫描电化学显微镜扫描电化学显微镜学习总结 张富纬 2016.9.17A small probe is scanned in short distance over a sample surfaceand a characteristic property of the sample is detected.Interaction of probe and sample!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, SECMScanning ele

2、ctrochemical microscopy (SECM) is the only technique able to detect(electro-) chemical reactions.SECM是唯一一种能够检测（电）化学反应的扫描探针技术。Resolution depends on the tip size!SECM ClassificationSECM归类于扫描探针技术Scanning probe techniques:3Basic Setup 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

3、前只能在小样品（1cm左右），平面上做一些基础性研究使用。Imaging Modes5 SECM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。Imaging Modes Negative FeedbackA reversible redox species is required !6Imaging Modes Positive Feedback7 由于

4、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+）。Feedback Mode - Measurement ConditionsCalculated approach curves with RG=10 according to J. L. Amphlett et al., J. Phys. Chem. B 102 (1998), 99468Feedback Mode9Array Scan for Surface Mappingxydata pointindividual line of array scan10Feedback ModeVisualiz

5、ation of electrochemical activity distribution on a sample surface.11Feedback Mode - ExampleRu3+Ru2+itip-400 mV12Feedback Mode - ExampleDifferences in local electrochemical activity e.g. due to surface impurities.General goal of SECM studies is the determination of the electron-transferkinetics at t

6、he sample surface!13Generator/Collector Mode (GC Mode)14Generator/Collector Mode - Example15Comparison Feedback and GC Mode5 mM Ru(NH3)63- in 100 mM KCl, RE: Ag/AgCl (3 M KCl), for GC: WE1: 2nd band Esample = -400 mV, WE2: 25 m Pt tipRu2+Ru3+0 mVRu3+Ru2+Ru3+Ru2+-400 mV16Comparison Feedback and GC Mo

7、de5 mM Ru(NH3)63- in 100 mM KCl, RE: Ag/AgCl (3 M KCl), for GC: WE1: 2nd band Esample = -400 mV, WE2: 25 m Pt tip+ sensitivity lateral resolution (diffusion profiles) time dependency+ lateral resolution high background currentredox mediator required17Practical Training SECM18Fe2+Fe3+500 mV Local exp

8、eriments due to mobile electrochemical cell Standard EC (OCP detection, polarization curves etc.) possible Only small area of samples is in contact with electrolyte, exchangeof solution prior to each new grid pointRECEElectrolyteWE19 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

9、无工业化应用价值。 Scanning Droplet Cell SDCScanning Droplet Cell Option SDCLocal experiments due to mobile electrochemical cellStandard EC (OCP detection, polarization curves etc.) possibleOnly small area of samples is in contact with electrolytePhotoelectrochemistryRECEElectrolyteinlet20SECM ApplicationsSE

10、CM 的应用领域ApplicationSECM is always useable when the local effects determine theproperty of the whole material (global appearance).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。2Fields of Application3 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。Reactivity on Stainless Steels 304

11、and 316J. Izquierdo et al., Electrochimica Acta 134 (2014), 167Stainless Steel 316Stainless Steel 3040.5 h4h7.5 h24 h0.5 h3h4Distribution ofiron (II) ions0.25 M HCl(GC-Mode)O2O2O2O2O2Corrosion of Steel Oxygen CompetitionE, iiTEConsumption ofOxygen is traced Variation of GC-modeJ. J. Santana et al.,

12、Electrochim. Acta 55 (2010), 44885Corrosion Protective CoatingsR. G. Duarte et al., Prog. Org. Coat. 74 (2012), 365PVC Plastisolcoated nickelfoils and 0.5 mMferrocene-methanol.Insulator assample surface Topography6Corrosion Protective CoatingsJ. Izquierdo et al., Prog. Org. Coat. 74 (2012), 5262-mer

13、captobenzimidazoleSECM image recordedin measuring solution of0.1 M Na2SO4 + 1 mMferrocenemethanol7E. Martinez-Lombardia et al., Electrochim. Acta 116 (2014), 895 mM ferrocenemethanolCorrosion - CopperImage with passive layerEffects due to crystallographicorientations of copperImage after removal of

14、passive layer8Dissimilar WeldJ. Jayaraj et al., J. Adv. Microsc. Res. 7 (2012), 214Tip reaction at 1.5 V:HNO3 + 2H+ 2e- HNO2 + H2O9Self-healing CoatingsA. Pilbth et al., Prog. Org. Coat. 75 (2012), 480Detection of Fe2+Detection of O2Microcapsules with linseed oil mixedinto epoxy resin coating.10Cata

15、lysis11Pt on C support (E-tek)Vulcan XC-72RPrintex L6Catalysis Fuel Cells Oxygen Reduction ReactionORR in alkaline solution, effect of carbon support H2O2 detectionM. H. M. T. Assumpo et al., Carbon 49 (2011), 284212Electrocatalytic Activity of Carbon FiberInvestigation of a single strand of carbon

16、fiber.3 mM -methylferrocenemethanol inphosphate bufferPseudo first order rateconstant via approach curvesV. S. Joshi et al., J. Phys. Chem. C 116 (2012), 970313Membrane TransportTransport phenomena in channels / membranes / pores14Diffusion through Membranes for Gas SensorsM. Nebel et al., Electroch

17、im. Acta 55 (2010), 792315Life Sciences - Biodegradable MaterialM. D. Pereda et al., Acta Biomater. 6 (2010), 177216Material Science Reduced Graphene Oxide on FabricsJ. Molina et al., Appl. Surf. Sci. 279 (2013), 4617BiosensorsBiosensor characterization18GC and RC-SECM for BiosensorsI. Morkvenaite-V

18、ilkonciene et al., RSC Adv. 4 (2014), 50064.19Cellular ActivityRelease or consumption20Respiration Activityd, t = 15 msTopographyM. Nebel et al. Angew. Chem. Int. Ed. 52 (2013) 633521Intra- and Extracellular Redox Processes Yeast CellI. Morkvenaite-Vilkonciene et al., Sensors and Actuators B: Chemic

19、al 228 (2016), 20022SECM Advanced Detection ModesSECM 前沿的检测方法AC-SECM 阻抗-SECM联用技术 All advantages of frequencydependent response No redox mediator necessary Diluted solution possibleImpedance spectra at each point of the scanned gridmeasured at the tip in close distance to the sample surface.2AC-SECMR

20、ECEnon-conductiveB. Ballesteros Katemann, A. Schulte, E. J. Calvo, M. Koudelka-Hep, W. Schuhmann, Electrochem. Commun. (2002), 4 134A. S. Baranski, P. M. Diakowski, J. Solid State Electrochem. (2004), 8, 683K. Eckhard, T. Erichsen, M. Stratmann, W. Schuhmann, Chem. Eur. J. (2008), 14, 3968RCtCdlRSRC

21、tCdlRSRStRSsRP1RP2CP1CP2conductive sampleRctCdlRsRP=charge transfer resistancedouble layer capacitancesolution resistancepolarization resistance (sample)3AC-SECMRECERECECdlRSRCtCdlRSRStRSsRP1RP2CP1CP2constantNo faradayprozessA. S. Baranski, P. M. Diakowski, J. Solid State Electrochem. (2004), 8, 683

22、K. Eckhard, T. Erichsen, M. Stratmann, W. Schuhmann, Chem. Eur. J. (2008), 14, 3968No faradayprozess RCtnon-conductiveRS increases during approachconductive samplealternative path through sample4Z/ZAC-SECM1 mM KCl, RE: Ag/AgCl, Ampl. 10 mVRCtCdlRSRStRSPRP1RP2CP1shortcutCP2RctCdlRsRP=charge transfer

23、resistancedouble layer capacitancesolution resistancepolarization resistance (sample)080132Glass0.5 kHzGlassPlatinumPlatinum6 kHZ0.5 kHz6 kHz4L = d/r5Comparison LEIS and AC-SECMEWE5-electrode configurationLEIS: Global AC perturbation atsample, measurement of local ACcurrent density to calculate loca

24、limpedance.3-electrode configurationAC-SECM: AC perturbation directly attip electrode and interactionunderneath measured, uses SECM tips(much smaller tips resolution) 6High resolution imaging in SECM成像技术Resolution in SECM Tip size (ratio of the size of tip and structure) Distance between data points

25、 (step size) Working distance (contrast) Detection mode and RG value of tip*Ratio of overall electrode radius tothe radius of the active tip surface2Fe2+Fe3+itip500 mV3Resolution in SECM Effect of Tip Size5 mM Fe(CN)64- in 100 mM KCl, RE: Ag/AgCl (3 M KCl), Etip = +500 mV, Feedback mode25 m Pt tipIn

26、crements: x = 12.5 m, y = 25 mWorking distance: 25 m10 m Pt tipIncrements: x = 5 m, y = 10 mWorking distance: 10 m4Resolution in SECM Effect of Tip SizeInteraction areadepends on tip sizeSignal averaged over tip size5Resolution in SECM Effect of Tip Size25 m Pt tipIncrements: x = 12.5 m, y = 10 mWor

27、king distance: 12.5 m5 mM Fe(CN)64- in 100 mM KCl, RE: Ag/AgCl (3 M KCl), Etip = +500 mV10 m Pt tipIncrements: x = 5 m, y = 10 mWorking distance: 5 m6Resolution in SECM - The Parameter Step WidthdrFast experiment, no loss ofinformation.Max. of information andwell resolved graphs.No additional inform

28、ation BUTincrease of the exp. duration.Loss of information (dottedlines) but fast experiments.7Resolution in SECM Effect of Step Width5 m12.5 m2 m50 m10 m Pt tip, working distance 5 m, 10 m y-increment, 5 mM Fe(CN)64- in 100 mM KCl, RE: Ag/AgCl (3 M KCl), Etip = +500 mV8I = i / i024681032104L = d/r1

29、210 m Pt tip,12.5 m x-increment, 10 m y-increment, 5 mM Fe(CN)64- in 100 mM KCl, RE: Ag/AgCl (3 M KCl), Etip = +500 mVWD 25 m (5r)WD 5 m (r)Working distancedetermines contrast!9Resolution in SECM EC determines the resolution! The choice of the electrode size and the parameter step width(distance bet

30、ween data points) is crucial.drThe positioning system has a sufficient repeatability (bidirectional15 m stepper motors and 10 nm piezo system).10Comparison Feedback and GC Mode5 mM Ru(NH3)63- in 100 mM KCl, RE: Ag/AgCl (3 M KCl), for GC: WE1: 2nd band Esample = -400 mV, WE2: 25 m Pt tipRu2+Ru3+0 mVR

31、u3+Ru2+Ru3+Ru2+-400 mV11Comparison Feedback and GC Mode5 mM Ru(NH3)63- in 100 mM KCl, RE: Ag/AgCl (3 M KCl), for GC: WE1: 2nd band Esample = -400 mV, WE2: 25 m Pt tip+ sensitivity lateral resolution (diffusion profiles) time dependency+ lateral resolution high background currentredox mediator requir

32、ed12working distance depends on tip sizetip crashConstant-Height vs. Constant-Distance Mode SECMWhen using a very small probe (sub-m),or scanning a rough sample, the distancedependency of the current signal cancause difficulties.loss of nearfield interaction13Constant-Height Mode SECMitipz-positioni

33、iElectrochemical activity and topography influence the tip signal(data interpretation difficult).14Constant-Distance Mode SECMitipz-positioniTip follows topography and the tip signal represents theelectrochemical activity.15magnitude / mVRequires specialvibratory SECM tipsConstant-Distance SECM Detection of shearforce interactions for current independentdistance controlPiezo elementAgitatorDetector8642010200250350400300frequency / kHzsolutionsf regime16MAG / mVConstant-Distance SECM Approach Curve012364161412108interaction rangecontactbulk signalset pointshearforcez-position