Reaction fronts and pulses in the CO oxidation on Pt. Theoretical analysis

A set of coupled nonlinear reaction-diffusion equations was formulated for the oxidation of CO on low-index plane Pt surfaces and solved for their spatiotemporal behavior using continuation techniques and the method of global connections. A two-variable model for Pt(111), consisting of the CO and O coverages as a function of time and space, gave rise to reaction fronts. In order to model the behaviour of Pt(111) or Pt(100), a third equation describing the respective adsorbate-driven phase transition had to be added. The resulting three-variable system predicts extended regions of excitability, where pulses can be triggered. The front or pulse velocities, as well as the critical radii for nucleation, were computed and compared to experimental data, where available.