Simultanous Determination of Diffusion Coefficients and Electrode Radii

When using cyclic voltammetry for electrochemical analysis with respect to reaction and transport parameters, it is often necessary to determine the diffusion coefficient D of the redox-active species. Although the Randles-Sevcik equation gives a straightforward relation between the voltammetric peak current and D, in common practice a problem arises from the fact that this is a relative determination. In particular, it relies on the knowledge of the electro-active area A of the electrode, which is in turn experimentally accessible from peak current data for a redox system with known D.

Cyclic Voltammetry at macro- and microelectrodes can be used to determine consistent values of D coupled to the (simultaneous) estimation of the electrode dimensions in non-aqueous electrolytes.

Furthermore, the pulsed gradient spin echo (PGSE) NMR experiment allows the determination of D in an electrolyte without changing the oxidation state of the examined species. Thus, the method is totally independent of current measurements and can be used to confirm the values for D obtained from CV-experiments.

Coworkers in this project

Rebekka Klinkhammer, Adrian Ruff, Janina Janisch, Christian Wolff and Jonas Zigelli

We closely cooperate with the group of

Hermann A. Mayer.

Poster presentation

A. Ruff, J. Janisch, C. Wolff, J. Zigelli, B. Speiser, V. Feldmann, and H.A. Mayer "Consistent Simultaneous Determination of Diffusion Coefficients and Electrode Dimensions by Means of Cyclic Voltammetry at Macro- and Microelectrodes", Electrochemistry 2010, Bochum, Germany

Publications from this projet

Consistent diffusion coefficients of ferrocene in some non-aqueous solvents: electrochemical simultaneous determination together with electrode sizes and comparison to pulse-gradient spin-echo NMR results, J. Janisch, A. Ruff, B. Speiser, C. Wolff, J. Zigelli, S. Benthin, V. Feldmann and H.A. Mayer, J. Solid State Electrochem. 15, 2083-2094 (2011).
(This article is dedicated to Professor Fritz Pragst on the occasion of his 70th birthday).