Dynamics and kinetics of CO oxidation on Pd(335): infrared chemiluminescence of CO 2

Abstract

Infrared chemiluminescence technique has been applied to steady-state carbon monoxide oxidation on a stepped Pd(335) surface, which consists of four-atom wide terraces of (111) orientation and monatomic-height steps, and the results are compared with those of a flat Pd(111) surface. The activity for CO oxidation was higher on Pd(335) than on Pd(111). The vibrational temperatures ( T v) of the product CO 2 molecules were substantially different on the stepped Pd(335) surface from on the Pd(111) surface, and the difference in T v between on Pd(335) and on Pd(111) is much larger at the surface temperature ( T s) of 850 K than at T s=650 K. These results suggest that, for the steady-state CO oxidation on the Pd(335) surface, the reaction takes place mostly on the step sites at T s=850 K, but the contribution from the terrace sites is increased significantly at T s=650 K.