Kinetic oscillations in the catalytic CO oxidation on Pt(100): Experiments

Under properly chosen conditions the rate of catalytic CO oxidation at a clean and well-defined Pt(100) surface exhibits sustained temporal oscillations which are also reflected by periodic changes of the work function (Δφ). These oscillations are associated with periodic changes of the surface structure between the CO-covered (θCO =0.5) 1×1–c(2×2) phase and an oxygen adlayer, respectively the reconstructed hex phase, as demonstrated by LEED. Laterally resolved experiments revealed that the surface phase transformations propagate in the form of trigger waves across the whole surface area. On the basis of detailed experiments and of literature data on the adsorptive properties of the two surface modifications of Pt(100) a microscopic picture on the mechanism of the observed phenomena is developed which also underlies a recently performed theoretical treatment.