J. Molina et al., Appl. Surf. Sci. 279 (2013), 46
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Biosensors
Biosensor characterization
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GC and RC-SECM for Biosensors
PVC Plastisol coated nickel foils and 0.5 mM ferrocenemethanol. Insulator as sample surface Topography
R. G. Duarte et al., Prog. Org. Coat. 74 (2012), 365
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Feedback Mode - Example
itip -400 mV
Ru3+ Ru2+
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Feedback Mode - Example
General goal of SECM studies is the determination of the electron-transfer kinetics at the sample surface!


3
Basic Setup 下图是整个仪器的
形貌
4
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。
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）
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Imaging Modes
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。
Printex L6
M. H. M. T. Assumpção et al., Carbon 49 (2011), 2842
Electrocatalytic Activity of Carbon Fiber
Investigation of a single strand of carbon fiber. 3 mM α-methyl ferrocene methanol in phosphate buffer
5
Imaging Modes – Negative Feedback
A reversible redox species is required !
6
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+）。
Imaging Modes – Positive Feedback
0.5 h
4h
7.5 h
24 h
Stainless Steel 304
Distribution of iron (II) ions 0.25 M HCl (GC-Mode)
3h 0.5 h
J. Izquierdo et al., Electrochimica Acta 134 (2014), 167
扫描电化学显微镜学习总结 张富纬 2016.9.17
Scanning Electrochemical Microscopy
扫描电化学显微镜
SECM – Classification
SECM归类于扫描探针技术
Scanning probe techniques: A small probe is scanned in short distance over a sample surface and 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, SECM Scanning electrochemical 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!
Pseudo first order rate constant via approach curves
Membrane Transport
Transport phenomena in channels / membranes / pores
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Diffusion through Membranes for Gas Sensors
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。
2
Fields of Application
燃料电池 催化剂 腐蚀 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。
3
Reactivity on Stainless Steels 304 and 316
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Catalysis – Fuel Cells Oxygen Reduction Reaction
ORR in alkaline solution, effect of carbon support
Pt on CБайду номын сангаасsupport (E-tek)
H2O2 detection
Vulcan XC-72R
7
Corrosion - Copper
Image with passive layer
Effects due to crystallographic orientations of copper
E. Martinez-Lombardia et al., Electrochim. Acta 116 (2014), 89
Stainless Steel 316
4
Corrosion of Steel – Oxygen Competition
E, i
O2
O2
O2
O2 O2
iT E
Consumption of Oxygen is traced
Variation of GC-mode
Corrosion – Protective Coatings
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Comparison Feedback and GC Mode
+ lateral resolution
high background current redox mediator required
+ sensitivity lateral resolution (diffusion profiles) time dependency
RE CE Electrolyte
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Scanning Droplet Cell – Option SDC
Local experiments due to mobile electrochemical cell Standard EC (OCP detection, polarization curves etc.) possible Only small area of samples is in contact with electrolyte Photoelectrochemistry
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Generator/Collector Mode (GC Mode)
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Generator/Collector Mode - Example
15
Comparison Feedback and GC Mode
-400 mV
0 mV
Ru3+ Ru2+
Ru3+
Ru2+
Ru2+
Ru3+
5 mM [Ru(NH3)6]3- in 100 mM KCl, RE: Ag/AgCl (3 M KCl), for GC: WE1: 2nd band Esample = -400 mV, WE2: 25 µm Pt tip
5 mM ferrocenemethanol
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Dissimilar Weld
Tip reaction at 1.5 V: HNO3 + 2H++ 2e- → HNO2 + H2O
J. Jayaraj et al., J. Adv. Microsc. Res. 7 (2012), 214
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Self-healing Coatings
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Feedback Mode - Measurement Conditions
Calculated approach curves with RG=10 according to J. L. Amphlett et al., J. Phys. Chem. B 102 (1998), 9946
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Feedback Mode
Detection of O2 Detection of Fe2+
Microcapsules with linseed oil mixed into epoxy resin coating.
A. Pilbáth et al., Prog. Org. Coat. 75 (2012), 480
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Catalysis
Fe3+
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Scanning Droplet Cell – SDC