First-principles investigation of Ag-Cu alloy surfaces in and oxidizing environment (Articolo in rivista)

Type
Label
  • First-principles investigation of Ag-Cu alloy surfaces in and oxidizing environment (Articolo in rivista) (literal)
Anno
  • 2008-01-01T00:00:00+01:00 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#doi
  • 10.1103/PhysRevB.77.075426 (literal)
Alternative label
  • Piccinin, Simone; Stampfl, Catherine; Scheffler, Matthias (2008)
    First-principles investigation of Ag-Cu alloy surfaces in and oxidizing environment
    in Physical review. B, Condensed matter and materials physics (Online)
    (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#autori
  • Piccinin, Simone; Stampfl, Catherine; Scheffler, Matthias (literal)
Pagina inizio
  • 075426-1 (literal)
Pagina fine
  • 075426-9 (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#numeroVolume
  • 77 (literal)
Rivista
Note
  • ISI Web of Science (WOS) (literal)
Http://www.cnr.it/ontology/cnr/pubblicazioni.owl#affiliazioni
  • School of Physics, The University of Sydney, Sydney; Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin (literal)
Titolo
  • First-principles investigation of Ag-Cu alloy surfaces in and oxidizing environment (literal)
Abstract
  • In this paper, we investigate by means of first-principles density functional theory calculations the (111) surface of the Ag-Cu alloy under varying conditions of pressure of the surrounding oxygen atmosphere and temperature. This alloy has been recently proposed as a catalyst with improved selectivity for ethylene epoxidation with respect to pure silver, the catalyst commonly used in industrial applications. Here, we show that the presence of oxygen leads to copper segregation to the surface. Considering the surface free energy as a function of the surface composition, we construct the convex hull to investigate the stability of various surface structures. By including the dependence of the free surface energy on the oxygen chemical potential, we are able compute the phase diagram of the alloy as a function of temperature, pressure, and surface composition. We find that, at temperature and pressure, typically used in ethylene epoxidation, a number of structures can be present on the surface of the alloy, including clean Ag(111), thin layers of copper oxide, and thick oxidelike structures. These results are consistent with, and help explain, recent experimental results. (literal)
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