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Structure and activity predictions on mono- and bi-metallic catalysts

Erünal, Ebru
The purpose of this study is to simulate PtIB (IB=Ag, Au, Cu) and PtPd bimetallic catalysts with Monte Carlo method for 201, 586, 1289, and 2406 atom containing clusters in the temperature range between 2981000K. The simulations were based on a coordination-dependent potential model in which binary interaction parameters were used. The binary interaction parameters were determined from the available thermodynamic data and classical thermodynamics mixing rules. The equilibrium structure of the clusters was dictated as a perfect cubo-octohedral shape. In the first part of this study, PtIb bimetallics were modelled in order to test the Monte Carlo program against the previously published work. In the second part of the study, the surface composition of PtPd bimetallic catalysts as a function of temperature and cluster size were estimated in order to offer further insight to the catalytic activity for CO oxidation reaction. It was found that at low temperatures Pd segregation took place on the catalyst. The Monte Carlo predictions were in good agreement with the published experimental data on the surface compositions.