Oxide ultra-thin films of nano-metric thickness may display novel properties related to the presence of the oxide/metal interface [1]. The possibility of exchange charge with the metallic substrate charge transfer allows the stabilization of unusual stoichiometries and charged adsorbates. In the case of iron oxide ultrathin films on Pt(111) these combined affect the chemical reactivity of the system. 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). The oxygen-rich phase is active in CO oxidation, the catalytic activity being higher than that of metal substrate under the same conditions [2]. The transformation of the FeO bi-layer exposed to oxygen into a FeO2 tri-layer and the reactivity of the FeO2 phase towards CO have been investigated by means of first principle DFT+U calculations [3]. The transformation of the film has been found to be strongly dependent on the local register between the oxide and the platinum substrate, in agreement with STM measurements which show irregularly shaped, flat islands decorating the Moiré template of FeO [4]. Moreover, a detailed analysis of the energetic involved in the oxygen incorporation and release processes at the oxide ultra-thin films have helped in indentifying the possible sites involved in the Mars-van Krevelen type mechanism of CO oxidation on these systems. [1] L. Giordano, G. Pacchioni, Acc. Chem. Res. 44 (2011) 1244 [2] Y.-N. Sun, Z.-H. Qin, M. Lewandowski, E. Carrasco, M. Sterrer, S. Shaikhutdinov, H.-J. Freund, J. Catal. 266, 359 (2009). [3] Y.-N. Sun, L. Giordano, J. Goniakowski, M. Lewandowski, Z.-H. Qin, C. Noguera, S. Shaikhutdinov, G. Pacchioni, H.-J. Freund, Angew. Chem. Inter. Ed. 49, 4418 (2010) [4] L. Giordano, M. Lewandowski, I.M.N. Groot, Y.N. Sun, J. Goniakowski, C. Noguera, S. Shaikhutdinov, G. Pacchioni, H.-J. Freund, J. Phys. Chem. C 114, 21504 (2010)
Giordano, L. (2012). Reactivity of metal-supported ultrathin films: The case of FeO/Pt(111). In ABSTRACTS OF PAPERS OF THE AMERICAN CHEMICAL SOCIETY.
Reactivity of metal-supported ultrathin films: The case of FeO/Pt(111)
GIORDANO, LIVIA
2012
Abstract
Oxide ultra-thin films of nano-metric thickness may display novel properties related to the presence of the oxide/metal interface [1]. The possibility of exchange charge with the metallic substrate charge transfer allows the stabilization of unusual stoichiometries and charged adsorbates. In the case of iron oxide ultrathin films on Pt(111) these combined affect the chemical reactivity of the system. 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). The oxygen-rich phase is active in CO oxidation, the catalytic activity being higher than that of metal substrate under the same conditions [2]. The transformation of the FeO bi-layer exposed to oxygen into a FeO2 tri-layer and the reactivity of the FeO2 phase towards CO have been investigated by means of first principle DFT+U calculations [3]. The transformation of the film has been found to be strongly dependent on the local register between the oxide and the platinum substrate, in agreement with STM measurements which show irregularly shaped, flat islands decorating the Moiré template of FeO [4]. Moreover, a detailed analysis of the energetic involved in the oxygen incorporation and release processes at the oxide ultra-thin films have helped in indentifying the possible sites involved in the Mars-van Krevelen type mechanism of CO oxidation on these systems. [1] L. Giordano, G. Pacchioni, Acc. Chem. Res. 44 (2011) 1244 [2] Y.-N. Sun, Z.-H. Qin, M. Lewandowski, E. Carrasco, M. Sterrer, S. Shaikhutdinov, H.-J. Freund, J. Catal. 266, 359 (2009). [3] Y.-N. Sun, L. Giordano, J. Goniakowski, M. Lewandowski, Z.-H. Qin, C. Noguera, S. Shaikhutdinov, G. Pacchioni, H.-J. Freund, Angew. Chem. Inter. Ed. 49, 4418 (2010) [4] L. Giordano, M. Lewandowski, I.M.N. Groot, Y.N. Sun, J. Goniakowski, C. Noguera, S. Shaikhutdinov, G. Pacchioni, H.-J. Freund, J. Phys. Chem. C 114, 21504 (2010)
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