Localized electrochemical mapping

Recently, two new electrochemical mapping techniques have become available the scanning vibrating electrode technique (SVET) and the localized electrochemical impedance spectroscopy (LEIS) technique. These techniques provide the capability to identify and monitor electrochemical behavior down to the micron level. These represent significant advances over traditional electrochemical methods (cyclic voltammetry, EIS, and even EQCM), which provide data that reflect only an average over the entire sample surface. Although such data are very useful, a major drawback is that no local or spatial information is obtained. 

Wittmann, M.W., R.B. Leggat, and S.R. Taylor. 1999. The detection and mapping of defects in organic coatings using local electrochemical impedance methods. J Electrochem Soc 146 (11) 4071. 

M. E., Macpherson, J.V., and Unwin, P.R. (2012) Electrochemical mapping reveals direct correlation between heterogeneous electron-transfer kinetics and local density of states in diamond electrodes. Angew. Chem. Int. Ed., 51(28), 7002 - 7006. 

Basame, S.B. and White, H.S. (1995) Scanning electrochemical microscopy of native titanium-oxide films - mapping the potential dependence of spatially-localized electrochemical reactions. Journal of Physical Chemistry, 99,16430-16435. 

The local electrochemical impedance spectroscopy (LEIS) " is another scanning probe technique that can map the ac impedance distribution over an electrode surface. In LEIS a sinusoidal voltage perturbation between the working and reference electrode is maintained by driving an ac current between the working... 

SECCM has been typically used to map the local electrochemical response and can also be used to modify a surface. Active species can be dissolved or suspended in the electrolyte solution and the contact between the liquid meniscus and the surface used to deliver the active species to a specific location on the surface. " The SECCM probe can be used to generate spots on a surface by approaching the probe to discrete points on the surface or generate patterns by moving the probe laterally across the surface while using a feedback loop to follow the topography of the surface and maintain the contact between the liquid meniscus and the surface. Applications of these methods are discussed herein. 

Localized electrochemical study of corrosion inhibition in microdefects on coated AZ31 magnesium alloy. Electrochim Acta 2010, 55(19), 5401-5406 (c) Bastos, A. C., Taryba, M. G., Karavai, O. V., Zheludkevich, M. L., Lamaka, S. V., Ferreira, M. G. S., Micropotentiometric mapping of local distributions of relevant to corrosion studies. Electrochem Commun 2010,12(3), 394—397. 

Recently, two new electrochemical mapping techniques have become available the scanning vibrating electrode technique (SVET) and the localized... 

Figure 55 Comparison of LEIS admittance maps for red (right) and black (left) defects under a vinyl coating on 2024-T3 after 35 h exposure to 0.6 M NaCl. The large admittance peak for the red defect indicates aggressive local corrosion. (From A. M. Miersch, J. Yuan, R. G. Kelly, S. R. Taylor. J. Electrochem. Soc. 146, 4449 (1999).)...

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