Stability of Surface and Bulk Oxides on Pd(111) Revisited by in Situ X-ray Diffraction

被引:23
作者
Kasper, N. [3 ]
Nolte, P. [3 ]
Stierle, A. [1 ,2 ,3 ]
机构
[1] Deutsches Elekt Synchrotron DESY, D-22603 Hamburg, Germany
[2] Univ Hamburg, Fachbereich Phys, D-20355 Hamburg, Germany
[3] Max Planck Inst Intelligente Syst, Max Planck Inst Metallforschung, D-70569 Stuttgart, Germany
关键词
OXIDATION; ADSORPTION; CATALYSTS; OXYGEN; PDO;
D O I
10.1021/jp307434g
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
We investigated the structure and formation of surface and bulk oxide on Pd(111) as a function of temperature and oxygen pressure from ultrahigh vacuum up to atmospheric pressures by means of in situ X-ray diffraction. Our X-ray diffraction data of the quasi 2-D surface oxide layer are compatible with the structural model of a Pd5O4 layer proposed by density functional theory. In the temperature range from 650 to 950 K, the formation of the Pd5O4 surface oxide layer can be described by a constant oxygen chemical potential, giving evidence that its formation takes place in local thermodynamical equilibrium with the surrounding oxygen gas phase. Above 950 K, the formation of the surface oxide layer is no longer observed, and a direct transition from chemisorbed oxygen to bulk oxide takes place, implying that the surface oxide layer is thermodynamically unstable under these conditions. Our results suggest that the oxygen chemical potential stability regime for the Pd5O4 surface oxide layer is much smaller than recently predicted by density functional theory.
引用
收藏
页码:21459 / 21464
页数:6
相关论文
共 22 条
[1]  
CONRAD H, 1977, SURF SCI, V65, P245, DOI 10.1016/0039-6028(77)90305-3
[2]   Modeling of heterogeneous catalysts using simple geometry supports [J].
Datye, AK .
TOPICS IN CATALYSIS, 2000, 13 (1-2) :131-138
[3]   Growth and decay of the Pd(111)-Pd5O4 surface oxide:: Pressure-dependent kinetics and structural aspects [J].
Gabasch, H ;
Unterberger, W ;
Hayek, K ;
Klötzer, B ;
Kresse, G ;
Klein, C ;
Schmid, M ;
Varga, P .
SURFACE SCIENCE, 2006, 600 (01) :205-218
[4]  
Griffith W. P., 1989, GMELIN HDB INORG SB2
[5]   Adsorption and abstraction of oxygen atoms on Pd(111): Characterization of the precursor to PdO formation [J].
Kan, Heywood H. ;
Shumbera, R. Bradley ;
Weaver, Jason F. .
SURFACE SCIENCE, 2008, 602 (07) :1337-1346
[6]   In situ spectroscopic study of the oxidation and reduction of Pd(111) [J].
Ketteler, G ;
Ogletree, DF ;
Bluhm, H ;
Liu, HJ ;
Hebenstreit, ELD ;
Salmeron, M .
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 2005, 127 (51) :18269-18273
[7]   Surface oxides on Pd(111): STM and density functional calculations [J].
Klikovits, J. ;
Napetschnig, E. ;
Schmid, M. ;
Seriani, N. ;
Dubay, O. ;
Kresse, G. ;
Varga, P. .
PHYSICAL REVIEW B, 2007, 76 (04)
[8]   CATALYTIC COMBUSTION OF METHANE [J].
LEE, JH ;
TRIMM, DL .
FUEL PROCESSING TECHNOLOGY, 1995, 42 (2-3) :339-359
[9]   Kinetic hindrance during the initial oxidation of Pd(100) at ambient pressures [J].
Lundgren, E ;
Gustafson, J ;
Mikkelsen, A ;
Andersen, JN ;
Stierle, A ;
Dosch, H ;
Todorova, M ;
Rogal, J ;
Reuter, K ;
Scheffler, M .
PHYSICAL REVIEW LETTERS, 2004, 92 (04) :4-461014
[10]   Two-dimensional oxide on Pd(111) [J].
Lundgren, E ;
Kresse, G ;
Klein, C ;
Borg, M ;
Andersen, JN ;
De Santis, M ;
Gauthier, Y ;
Konvicka, C ;
Schmid, M ;
Varga, P .
PHYSICAL REVIEW LETTERS, 2002, 88 (24) :2461031-2461034