AVS 52nd International Symposium
    Surface Science Wednesday Sessions
       Session SS2-WeM

Paper SS2-WeM2
Modeling of Nanoscale Spatiotemporal Behavior in CO-oxidation on Pd(100)

Wednesday, November 2, 2005, 8:40 am, Room 203

Session: Reactions on Metals & Oxides
Presenter: D.-J. Liu, Iowa State University
Authors: D.-J. Liu, Iowa State University
J.W. Evans, Iowa State University
Correspondent: Click to Email
For CO-oxidation on metal surfaces, a few STM studies have begun to explore nanoscale spatial organization in titration reactions, and FIM studies have revealed propagation of near-atomically sharp reaction fronts. However, there has been almost no realistic atomistic modeling of such processes. Thus, we have developed such a model for CO-oxidation on Pd(100) exploiting DFT calculations and experimental data, e.g., on adspecies ordering, to accurately determine the small but significant lateral interactions between adspecies. Efficient kinetic Monte Carlo algorithms are developed to study model behavior. Below 300 K, the system can be characterized by coadsorption of CO and oxygen with different ordering structures. Between 300 K and 350 K, reaction occurs involving sharp moving fronts between domains of CO and oxygen. In this regime, chemical diffusion of CO is greatly inhibited due to strong interactions between adsorbates. (At higher temperatures, the interface between CO- and oxygen-rich domains becomes an extended chemical wave, familiar from PEEM studies, the profile reflecting the coverage dependent CO diffusion.) Finally, for nanoscale systems (such as field emitter tips or supported metal clusters), fluctuation-induced transitions between reactive and near-poisoned steady states were also analyzed.