Contribution of electrochemical impedance spectroscopy to the investigation of the electrochemical kinetics

Abstract

A general framework related to the investigation of electrochemical reaction mechanism under linear regimes is established. The problem of the identification of the parameters of a model of heterogeneous reaction mechanism is discussed from the data obtained through the electrochemical impedance and the electrogravimetric transfer function. If the model involves ℓ independent differential equations dealing with ℓ coverage rates of the electrode surface by absorbed reaction intermediates, the impedance provides 2ℓ + 1 independant quantities which could lead to 2ℓ + 1 kinetic rate constants. The electrogravimetric transfer function leads to ℓ + 1 extra independent quantities. Therefore, by using simultaneously the two approaches, it can be possible to obtain not only the rate constants but also the atomic mass of the adsorbed reaction intermediates. Processes where only one adsorbed reaction intermediate is involved is thoroughly analyzed by ac electrogravimetry and the possible shapes of the transfer functions which can be experimentally obtained is listed.