Mechanistic aspects of the linear stabilization of non-stationary electrochemical oscillations.

The problem of non-stationarity in experimentally recorded time-series is common in many (electro)chemical systems. Underlying this non-stationarity is the slow drift in some uncontrollable parameter, and it occurs in spite of the fact that all controllable parameters are kept constant. Particularly for electrochemical systems, some of us have recently suggested [J. Phys. Chem. C, 144, (2010), 22262-22268] an empirical method to stabilize experimental time-series. The method was exemplified for the electro-oxidation of methanol and different patterns were satisfactorily stabilized. In this paper we further elaborate some mechanistic aspects of this method and test it for the electro-oxidation of formaldehyde, a system that has some resemblance with the electro-oxidation of methanol, but produces a richer dynamics. In terms of the reaction mechanism, we were able to describe the coupling and to separate the surface processes of the two sub-systems: the fast one (or the core-oscillator) and the slow one, responsible for the drift.