The Structure and Reactivity of Oxide Thin Films Grown on Transition Metal Surfaces

Abstract

Epitaxially grown oxide and sulfide films [FeO_x and ZrO₂ on Pt(111), V₂O₃ on Au(111), S on flat and vicinal Mo(100) and Re(0001)] and oxide islands (TiO₂, ZrO₂, FeO, V₂O₃ on Rh) were produced on transition metal surfaces. Their structure has been studied by LEED-surface crystallography and by scanning tunneling microscopy. The reactivity of the oxide films is probed by chemisorption and by carrying out catalytic reactions at high pressures using these oxide-metal systems. The ordered FeO_x films are unreactive for chemisorption. The sulfur layers order into a large number of complex structures as a function of coverage, thereby inducing restructuring of the metal substrate. The periphery of the oxide islands deposited on metals proved to be very reactive for the hydrogenation of molecules with polar C-O bonds (CO, CO₂ and acetone).