Monte Carlo simulation for the formation of subsurface oxygen on Pt(100) and its elimination by CO oxidation

The process of CO oxidation on Pt(100) at low pressure has a complicated behavior by spontaneously reconfiguring the structure of the surface (1 × 1) to a quasi-hexagonal (hex). The interface between the empty hex surface and chemisorbed O allows its diffusion under the layer of platinum atoms. Either on the stage of subsurface oxygen formation or on its subsequent elimination, the CO oxidation process is quite complex, implying both a phase change in the surface structure 1 × 1 ↔ hex and particle migration between phases. Using a Monte Carlo simulation we were able to mimic the experimental phenomenon finding an optimal temperature and a CO partial pressure for this complex process.