Adsorption-desorption kinetics of carbon monoxide on a palladium (100) single crystal surface modified with sulfur

Abstract

The thermal desorption spectra, the adsorption isotherms, and the absolute rates of adsorption and desorption of carbon monoxide were measured on the (100) plane of palladium modified with sulfur adatoms. A small amount of S adatoms reduced the thermal desorption energy from ~ 34 kcal mol −1 to ~ 9 kcal mol −1. During adsorption, the absolute desorption rate increased with increasing ambient CO pressure. This kind of pressure dependency was depressed by a quarter monolayer of S. The absolute adsorption rate as a function of CO coverage did not depend on the crystal temperature of the clean surface, but it showed a negative temperature-dependence with increasing sulfur coverage.