Structure and Surface Reactivity of Ultra-Thin Pt/W(111) Films

We report on the structure, the chemisorption and the electrocatalytic properties of multilayer (2.2, 3.3 and 5.5 physical monolayers) Pt films deposited on W(111) elaborated by molecular beam epitaxy. The Pt/W(111) surfaces were characterized by low-energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV). Pronounced changes of the surface reactivity were noticed as the Pt coverage is decreased. In particular, the affinity for under-potentially deposited hydrogen (Hupd) and hydroxyl (OHads) species and the ability to electrooxidize a monolayer of COads were depreciated in agreement with strain and ligand effects.