The presence of a second, inert metal component in an alloy surface can have a dramatic effect on the adsorption kinetics compared to that predicted from simple site-blocking. This is due to the important role that is often played by the modifier precursor state [Xu and Koel, J. Chem. Phys., in press]. In order to more clearly reveal details concerning this state, the adsorption kinetics and thermodynamics of CO on Pt(111) and two ordered Sn/Pt(111) surface alloys have been studied. The thermodynamics of CO adsorption on Pt(111) is only slightly influenced by the presence of Sn. In contrast to the adsorption thermodynamics, the nature of the adsorption kinetics depends strongly on the presence of Sn. This difference can be explained by the fact that the thermodynamics of strong chemisorption is mainly determined by chemical bonding forces, while the adsorption kinetics can be determined by physisorption forces because of their influence on precursor states.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Materials Chemistry