6533b7d5fe1ef96bd126453e

RESEARCH PRODUCT

Surface phase transitions at O and CO catalytic reaction on Pd(111)

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Abstract The model has been proposed to simulate numerically the reaction O + CO → CO2 and occurring phase transitions on Pd(1 1 1) surface. We calculate the phase diagram for this system by kinetic Monte Carlo method. It shows the phase transitions p ( 2 × 2 ) O → 3 × 3 R 30 O ° and p ( 2 × 2 ) O → 3 × 3 R 30 O ° → p ( 2 × 1 ) O with increase of CO coverage for room and intermediate temperatures, respectively, while in the low temperature limit the direct p(2 × 2)O → p(2 × 1)O phase transition is observed. We demonstrate that the reaction rate is the crucial factor determining the occurrence of the p(2 × 1)O phase and vanishing of the 3 × 3 R 30 O ° with decrease of temperature. The results indicate that the reaction proceeds inside both the p(2 × 2)O and 3 × 3 R 30 O ° phases, but on the perimeter of the domains of p(2 × 1)O structure.