Mechanistic classification of electrochemical oscillators - operational experimental strategy

We consider a comprehensive classification scheme of oscillatory electrochemical systems with respect to the mechanistic basis of their kinetic instability. Four principal oscillator categories are distinguished depending on the mechanistic role of the potential drop across. the electrode I electrolyte interface (double layer potential) and of the chemical species involved. In a comparative characterization. the typical experimental behavior of the four oscillator categories is described when subjected to various Identification tests such as stationary and scanned cyclic voltammetric profiles, bifurcation behavior, impedance spectra and feedback control methods. It is shown that each category corresponds to a specific class of kinetic prototype models. Experimental example systems as well as numerical models taken from the literature are discussed in the context of their corresponding oscillator class. Moreover. an operational experimental procedure for a systematic mechanistic categorization of an unknown etectrochemical oscillator is proposed. It is argued that an initial mechanistic categorization significantly facilitates the subsequent clarification of the relevant chemical steps of the unknown electrochemical oscillator. (C) 1999 Elsevier Science S.A. All rights reserved.