Dynamic Monte Carlo simulations of O2 adsorption and reaction on Pt(1 1 1)

Temperature-programmed dynamic Monte Carlo simulations describe the time evolution of adsorption and desorption of molecular oxygen, its dissociation, and atomic oxygen diffusion. A hexagonal lattice containing six adsorption sites per unit cell represents the Pt(1 1 1) surface. The temperature is increased linearly with time, starting with an empty initial surface. Temperature effects on the rate of molecular oxygen adsorption are incorporated through the temperature dependence of the O2 sticking coefficient and that of the flux of molecules impinging the surface at a given pressure. The results illustrate the mechanisms by which molecular oxygen cannot be adsorbed at temperatures above 155 K.