The binding energy of CO on clean and sulfur covered platinum surfaces

Abstract

The desorption of CO from clean Pt(111) and (100), and from the same surfaces with partial overlayers of sulfur, was studied by Thermal Desorption Spectroscopy. The method of desorption rate isotherms was employed for data analysis. The desorption of CO from the (111) surface and both surfaces with ordered sulfur overlayers can be described as a first order process with coverage dependent activation energies. The desorption of CO from the clean Pt(100) surface is complicated by the dynamic interaction of the molecule with a thermally activated change of platinum surface structure. On both platinum faces surface sulfur decreases the initial binding energy of CO. As the CO concentration increases, its binding energy decreases very rapidly. This is due to a repulsive interaction which exists between co-adsorbed species.