Choice of experimental method induced by structural properties of mechanisms

The interest of checking structural properties of reaction mechanisms prior to any attempt at estimating their kinetic parameters is illustrated by considering the identifiability of the parameters of the Volmer-Heyrovsky mechanism. The technique employed applies to any of the small-signal methods used for the study of electrochemical mechanisms, as well as to signals involving large deviations. It turns out that steady-state measurements, electrochemical impedance spectroscopy and linear sweep voltammetry do not make it possible to estimate the kinetic parameters unambiguously, even from noise-free data, contrary to electrogravimetry. This type of analysis, which seems still largely ignored among electrochemists, can be used for the choice of experimental procedures to be employed.