Site switching in steady state carbon monoxide oxidation on platinum(113)

Reaction sites in CO oxidation were studied at the steady state over stepped Pt(113)=(s)2(111)x(001) by angular and velocity distributions of desorbing product CO2. Two reaction sites, (111) and (001) sites, are operative. The (111) site preference is suppressed with increasing CO pressure in the active region where the reaction is roughly first order in CO. The preference is reversed to the (001) site fairly below critical CO pressures where the reaction begins to be retarded by CO. Below 500 K, on the other hand, the site switching does not proceed quickly. The translational energy of CO2 is characteristic of each site throughout the site switching. O 1999 Elsevier Science B.V. All rights reserved.