Influence of extended interactions on the surface dynamics in the catalytic CO oxidation on Pt single crystal substrate

Abstract

The simulation of kinetic oscillations and dynamics of CO chemical fronts propagating through a Pt(100) substrate by the use of cellular automaton techniques, is reexamined with an extended interacting neighborhood model, that allows for a temperature dependence of the reaction constants. These new cellular automaton rules account for the structural phase transformations of the Pt substrate, the reaction kinetics of the adsorbed phase, and diffusion of adsorbed species. In addition it provides a richer variety of surface patterns formation. Specifically, we consider the effect of lateral interactions between adsorbed particles, this is taken into account our simulations through the definition of a site-dependent reaction constant, that is dependent of the state of the metal. This is achieved by considering an extended neighborhood of next-nearest-neighbors and beyond. For CO–CO and O–O attractive interactions, the oscillation amplitude increases as the interaction energy increases. It is shown herein that the presence of strong attractive lateral interactions in reacting adsorbate can lead to the spontaneous formation of traveling waves. The diffracting properties of the waves moving in the media with different composition (one part clean and other containing inert sites) are also investigated. It is shown that beyond a critical coverage, waves traveling from a clean part of the crystal to a partially covered surface are adsorbed by the media, destroying their coherence. Finally, it is shown that appropriate initial conditions can also lead to the formation of double stable spirals.