Potentiodynamic electrochemical impedance spectroscopy
G. A. Ragoisha* and A. S. Bondarenko
Electrochimica Acta 50 (2005) 1553-1563.

Physico-Chemical Research Institute, Belarusian State University, 220050, Minsk, Belarus

Keywords: electrochemical impedance spectroscopy, EIS, PDEIS, Faradaic impedance, double layer capacitance, pseudocapacitance and resistance of adsorption, impedance of diffusion, Warburg constant, charge transfer resistance, equivalent circuit, analysis of multivariate impedance data, underpotential deposition, upd, bismuth, aniline electropolymerisation.

Potentiodynamic electrochemical impedance spectroscopy (PDEIS) uses virtual instruments to acquire, by means of a common potentiostat, multidimensional dependencies that characterise variations of dc current and frequency response in the same potential scan. Unlike classical EIS, which finds the whole equivalent circuit in stationary states, PDEIS finds, in potentiodynamic systems, only those elements of equivalent circuits that are needed to decompose the ac response in a limited range of frequencies. The decomposition of ac response into components belonging to different elements is provided by a built-in spectrum analyser, which gives dependences of equivalent circuit parameters on variable potential. The new technique develops the idea, originally suggested by D.E. Smith, of versatile characterisation of the electrochemical response in a simple computerised experiment. PDEIS solves this problem with the use of multi-frequency potentiodynamic probing based on analysis of streams of wavelets. The use of the additional variable (electrode potential) helps to disambiguate the equivalent circuit analysis. The PDEIS performance is illustrated on systems of various kinds: a reversible system (ferricyanide redox transformations on glassy carbon and platinum electrodes), a system that is locally reversible but shows different responses in forward and backward scans (Bi upd on Au) and a strongly irreversible variable system (initial stages of aniline electropolymerisation on gold).

*Presented at the International Workshop on Electrochemistry of Electroactive Materials, WEEM-2003, 2227 July 2003, Bad Herrenalb, Germany

Full-text preprint (PDF, 372 KB) Electrochim. Acta 50 (2005) 1553, preprint.

Supplementary files. Potentiodynamic impedance spectra of reversible and irreversible systems. The 3D objects show variable frequency response and dc response as functions of electrode potential acquired in the same potential scan.
1. Animation to Fig. 4. Spectrum of a reversible system (ferricyanide redox transformations on glassy carbon).
2. Animation to Fig. 12. Spectrum of an irreversible system (initial stages of aniline electropolymerisation on gold).

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