Carbon monoxide adsorption on a Pt80Fe20(111) single-crystal alloy

Abstract It has been previously shown that the topmost layer of the Pt 80 Fe 20 (111) single-crystal alloy is characterized by a large Pt surface segregation and two types of Pt atoms. Carbon monoxide adsorption has been studied on that surface by TDS, HREELS and work-function changes at 120 K. HREELS indicates that on-top CO is the prevalent adsorbed species, although bridge-bonded CO is also present near saturation. The general shape of work-function changes exhibits a similar behaviour on the alloy and on Pt(111). TDS spectra show two main peaks which have been related to the two kinds of surface Pt atoms. It is proposed that the presence of iron atoms in the subsurface induces the observed decrease in the CO binding energy.