Gabrielli C, Keddam M, Portail N, Rousseau P, Takenouti H, Vivier V. Electrochemical Impedance Spectroscopy Investigations of a Microelectrode Behavior in a Thin-Layer Cell: Experimental and Theoretical Studies.
J Phys Chem B 2006;
110:20478-85. [PMID:
17034233 DOI:
10.1021/jp063055h]
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Abstract
Electrochemical impedance spectroscopy experiments were performed on a microdisk electrode in a thin-layer cell using a scanning electrochemical microscope for controlling the cell geometry. Experimental data showed that when the thin-layer thickness diminished, an additional low-frequency response appeared. It was ascribed to the radial diffusion of the electroactive species and was strongly dependent on the thin-layer dimensions (both thickness and diameter). Moreover, the numerical simulation of the impedance diagrams by finite element method calculations confirmed this behavior. An equivalent circuit based on a Randles-type circuit was proposed. Thus, the diffusion was described by introducing two electrical elements: one for the spherical diffusion and the other for the radial contribution. A nonlinear Simplex algorithm was used, and this circuit was shown to fit the impedance diagrams with a good accuracy.
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