Oscillating Structural Changes in Catalytic Reactions
Under appropriate pO2/ PCO, T-conditions kinetic oscillations may arise during catalytic CO oxidation which have been studied on Pt(100), Pt(110) and Pt(210) single crystal surfaces in the 10-5 and 10-4 Torr range. The mechanism of the oscillations could be traced back to periodic structural transformations of the surface via the operation of an adsorbate-induced surface phase transition. Due to the strong mass transport of 50% of the surface atoms that is associated with the 1×1 ⇌ 1×2 phase transition of Pt(110) one may also observe a facetting of the surface during catalytic CO oxidation. The facetted Pt(110) surface was identified as a non-equilibrium structure of the Turing type, since LEED investigations demonstrated that the facets form a regular pattern on the surface with a lateral periodicity of ~ 100 Å. This interpretation could be confirmed by a Monte Carlo simulation which reproduced the formation of regular facet patterns on Pt(110) during catalytic CO oxidation.
KeywordsPhase Transition Single Crystal Surface Lateral Periodicity Spatial Pattern Formation Torr Range
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