Oxide ultra-thin films of nano-metric thickness may display novel properties related to the presence of the oxide/metal interface. The possibility of exchanging charge with the metallic substrate allows the stabilization of unusual stoichiometries and charged adsorbates, affecting the chemical reactivity of the system. FeO films grown on Pt(111) are indeed more active in CO than the bare metal substrate under the same conditions. The reaction mechanism proceeds as follows: under oxygen-rich conditions, the FeO/Pt(111) film incorporates oxygen and transforms itself  in a new phase, of  stoichiometry FeOx  (x ~ 1.8 - 1.9). CO is then easily oxidized by the oxygen-rich film.A detailed analysis of the energetics involved in the processes of oxygen incorporation and release, performed by means of first principle DFT+U calculations, have helped in indentifying the possible sites involved in the Mars-van Krevelen type mechanism of CO oxidation on the oxide ultra-thin film.

Reactivity of metal-supported ultrathin films: The case of FeO/Pt(111)

244th National Meeting (2012)

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