Modelling of phase transitions and reaction at CO adsorption on oxygen precovered Pd(1 1 1)

Using the interaction parameters up to the third neighbors and activated form of O and CO diffusion and their reaction, the model has been proposed for Monte-Carlo simulations describing the catalytic O + CO !CO2 reaction and occurring phase transitions on Pd(1 1 1) surface. Upon adsorption of CO the pre-adsorbed oxygen transforms from p(2 2)O phase into ffiffiffi 3 p ffiffiffi 3 p R30 O and ffiffiffi 3 p ffiffiffi 3 p R30 O! pð2 1ÞO phases in the limit of room and moderate temperatures, respectively.We demonstrate that the kinetic effects determine both the occurrence of the p(2 1)O and disappearance of the ffiffiffi 3 p ffiffiffi 3 p R30 O phases at moderate and low temperatures, respectively. Using reaction rate as a fit parameter, we show that at room temperature the start of the reaction can be synchronized with the occurrence of ffiffiffi 3 p ffiffiffi 3 p R30 O phase.