Kinetic oscillations in the catalytic CO oxidation on Pt(100): Theory

Abstract

Experimental investigations on the catalytic oxidation of CO on well-defined Pt(100) surfaces at low pressures (∼10−4 Torr) revealed under certain conditions the occurrence of kinetic oscillations which were associated with periodic transformations of the surface structure propagating wave-like across the surface area. Based on experimental information about the various elementary steps involved (adsorption, desorption, surface reaction, adsorbate-induced surface structural transformation) a set of coupled differential equations describing the kinetics of the various processes was established. A simplified version of these equations allows analytical treatment and provides qualitative insight into the occurrence of oscillations through linear stability analysis. Numerical solution of the full set of reaction-diffusion equations reproduces the essential spatio-temporal features of the experimental observations, although full quantitative agreement would still require better adjustment of the parameters involved as well as further refinement of the model.