Surface composition of clean and oxidized Pd75Ag25(100) from photoelectron spectroscopy and density functional theory calculations
Journal article, 2012
High resolution photoelectron spectroscopy and density functional theory calculations have been used to study the composition of clean and oxidized Pd75Ag25( 100). The results for the clean surface confirm earlier reports of surface segregation by Wouda et al. (1998), where the top most layers are rich in Ag. The Pd 3d core level component from the surface region is observed at higher binding energies than the contribution from the bulk which is found to be a signature of Pd embedded in Ag. Low energy electron diffraction and scanning tunneling microscopy measurements reveal that oxidation of the Pd75Ag25(100) surface results in a (root 5 x root 5)R27 degrees-O structure similar to the one reported for Pd(100). The calculations suggest that the stable structure is a PdO(101) monolayer supported on a (100) surface rich in Ag at the interface to the stoichiometric alloy. The calculated core level shifts for the oxidized surface are in good agreement with the experimental observations.
pd-ag
mu-m
Pd75Ag25(100)
segregation
PdAg alloy
Surface oxide
Density
hydrogen
oxidation
pd(111)
heat-treatment
Core level shifts
Photoelectron spectroscopy
alloys
palladium-silver
electron-spectroscopy
Author
L. E. Walle
Norwegian University of Science and Technology (NTNU)
Henrik Grönbeck
Chalmers, Applied Physics, Chemical Physics
Competence Centre for Catalysis (KCK)
V. R. Fernandes
Norwegian University of Science and Technology (NTNU)
S. Blomberg
Lund University
M. H. Farstad
Norwegian University of Science and Technology (NTNU)
K. Schulte
Lund University
J. Gustafson
Lund University
J. N. Andersen
Lund University
E. Lundgren
Lund University
A. Borg
Norwegian University of Science and Technology (NTNU)
Surface Science
0039-6028 (ISSN)
Vol. 606 23-24 1777-1782Subject Categories (SSIF 2011)
Chemical Sciences
DOI
10.1016/j.susc.2012.07.006