Development of scanning electrochemical microscopy in the transient mode and its limitations Seminar

The scanning electrochemical microscopy (SECM) is a powerful technique for sensing the local (electro)chemical reactivity of various types of interfaces. It is also used for studying reaction mechanisms taking advantage of the high mass transfer coefficient at the microelectrode in SECM configuration. In a recent series of papers, the Bard’s group has investigated adsorption processes using the surface interrogation mode to quantify electrogenerated oxides (adsorbed oxygen species) on gold and platinum electrodes at neutral pH [1, 2]. In this presentation, we will introduce the ac-SECM, which is a transient technique based on electrochemical impedance spectroscopy for studying adsorbed intermediates involved in multi-step mechanisms [3,4].
In a first part, a special attention will be paid to the description of the technique, the introduction of new complex transfer functions, and the characterization of the diffusion process occurring between the tip and the substrate. In a second part, the ac-SECM will be used for the characterization of specific adsorbed intermediates involved in the hydrogen evolution reaction (HER) and in the oxidation of halide ions. Then, in a last part, the limitation of the technique such as the spatial resolution, the frequency range investigated, and the time constant [5] that can be reached will be discussed.

References
[1] Rodriguez-Lopez, J.; Alpuche-Aviles, M. A.; Bard, A. J. Journal of the American Chemical Society 2008, 130, 16985-16995.
[2] Rodriguez-Lopez, J.; Bard, A. J. Journal of the American Chemical Society 2010, 132, 5121-5129.
[3] D. Trinh, M. Keddam, X.R. Novoa, V. Vivier. ChemPhysChem 2011, 12, 2169-2176.
[4] D. Trinh, M. Keddam, X.R. Novoa, V. Vivier. ChemPhysChem 2011, 12, 2169-2176.
[5] D. Trinh, E. Maisonhaute, V. Vivier. Electrochem. Comun. 2012, 16, 49-52.