CO OXIDATION AT Pd(111) SURFACE
V. Kuzovkov and G. Zvejnieks,
V. Petrauskas and E. Tornau (Semiconductor Physics Institute, Vilnius, Lithuania)

Catalytic surface reactions still remain an actual research topic, which is supported by both search of effective catalysts in automotive industry and challenges for applicability of theoretical methods. In collaboration with the Semiconductor Physics Institute (Vilnius), the model has been proposed to simulate numerically the reaction O + CO → CO₂ and occurring phase transitions on Pd(111) surface. We calculated the phase diagram for this system by means of the kinetic Monte Carlo method. We have shown existence of the phase transitions p(2x2)_o→√3x√3R30°_o and p(2x2)_o→√3x√3R30°_o→p(2x1)_o with increase of CO coverage for room and intermediate temperatures, respectively, while in the low temperature limit the direct p(2x2)_o→p(2x1)_o phase transition is observed. We demonstrated that the reaction rate is the crucial factor determining the occurrence of the p(2x1)_o phase and vanishing of the 3x√3R30°_o with temperature decrease. The results of correlation function analysis indicated that the reaction proceeds inside both the p(2x2)_o and √3x√3R30°_o phases, but on the perimeter of the domains of p(2x1)_o structure.

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