Monomer–dimer CO–O2 catalytic reaction on (0 0 1) surface and subsurface of a simple cubic structure

The presence of subsurface oxygen has been observed experimentally in monomer–dimer (CO–O2 and NO–CO) surface reactions. By the use of Monte Carlo simulation the effect of this subsurface oxygen in CO–O2 catalytic reaction on (0 0 1) surface and subsurface of a simple cubic structure is studied. We have carried out detailed analysis of the effect of increasing the subsurface neighbours on the phase diagram of the CO–O2 reaction. It is shown that the presence of subsurface completely eliminates the usual second-order phase transition of this reaction. It is also shown that increase in the number of subsurface neighbours shifts the single-transition point towards higher CO concentration value. When first, second and third subsurface nearest-neighbours are considered, the single-transition point is shifted to the stoichiometric ratio of 2/3.