Mechanistic classification of electrochemical oscillators - operational experimental strategy

We consider a comprehensive classification scheme of oscillatory electroche mical systems with respect to the mechanistic basis of their kinetic instab ility. Four principal oscillator categories are distinguished depending on the mechanistic role of the potential drop across. the electrode I electrol yte interface (double layer potential) and of the chemical species involved . In a comparative characterization. the typical experimental behavior of t he four oscillator categories is described when subjected to various Identi fication tests such as stationary and scanned cyclic voltammetric profiles, bifurcation behavior, impedance spectra and feedback control methods. It i s shown that each category corresponds to a specific class of kinetic proto type models. Experimental example systems as well as numerical models taken from the literature are discussed in the context of their corresponding os cillator class. Moreover. an operational experimental procedure for a syste matic mechanistic categorization of an unknown etectrochemical oscillator i s proposed. It is argued that an initial mechanistic categorization signifi cantly facilitates the subsequent clarification of the relevant chemical st eps of the unknown electrochemical oscillator. (C) 1999 Elsevier Science S. A. All rights reserved.