Phase mixing and phase separation accompanying the catalytic oxidation of CO on Ir{1 0 0}

Lerotholi, T. J.; Held, Georg; King, David A.

doi:10.1016/j.susc.2006.12.067

Cited by 18 publications

(63 citation statements)

References 29 publications

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“…Similar arrangements of oxygen atoms are also found during CO oxidation on Ir(100). [50] Significant displacements of the substrate Ir atoms are found in both experiments and theoretical calculations, and are invoked to explain the preference for (2 1)(h) ordering. However, we find that while displacements of Pt atoms do play a role in stabilizing the (n 1) structure, this is just one contributing factor.…”

Section: Dft Resultsmentioning

confidence: 91%

Interactions between Oxygen Atoms on Pt(100): Implications for Ordering during Chemisorption and Catalysis

Liu

Evans

2010

ChemPhysChem

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We present a DFT analysis of the interactions between chemisorbed oxygen on the unreconstructed (1x1)-Pt(100) surface. These interactions control ordering of O not just for single-species adsorption, but also within O domains during coadsorption and reaction with other species such as CO. The calculations indicate that O prefers bridge sites, as deduced previously. In addition, we find a large difference in the interactions between O at different types of bridge site pairs separated by one lattice constant. There is strong repulsion for pairs separated by a Pt atom, but only a weak interaction for pairs separated by a fourfold hollow site. This finding elucidates the tendency for striped (nx1)-O ordering often observed in chemisorption and reaction studies.

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Section: Dft Resultsmentioning

confidence: 91%

Interactions between Oxygen Atoms on Pt(100): Implications for Ordering during Chemisorption and Catalysis

Liu

Evans

2010

ChemPhysChem

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“…There have been several studies performed on (100) platinum metal surfaces such as Pt 8–10, Pd 11–13, and Rh 14–16. Although Ir surface is considered to be one of the most reactive catalysts 17, there are few studies for CO oxidation on Ir(100) surfaces 18. It is well established that CO oxidation on metallic surfaces can be regarded as a prototype for the Langmuir–Hinshelwood (L–H) mechanism 17, 19.…”

Section: Introductionmentioning

confidence: 99%

“…Experimentally, CO oxidation has been investigated on Ir(111) 31–34 and Ir(110) surfaces 35. Lerotholi et al 18 have examined by low‐energy electron diffraction (LEED) and temperature‐programmed desorption (TPD) CO adsorption on Ir(100) surface precovered with 0.5 ML O at 188 and 300 K. They noticed that a mixed c(4 × 2)–(2O + CO) overlayer was formed at 188 K, and upon heating all CO molecules were oxidized as CO 2 from the surface in three states (α‐CO 2 ) at 230 K, (β‐CO 2 ) at 330 K, and (γ‐CO 2 ) at 430 K. They found that β and γ desorption temperatures for CO 2 are the same and independent on the initial coverage of CO and O and the selectivity toward CO oxidation is always 100%. The dependence of reaction mechanism and kinetics on adsorbate coverage is an important factor behind the large differences in activation energies and pre‐exponential factors 16.…”

Section: Introductionmentioning

confidence: 99%

Catalytic oxidation of CO on Ir(100)

Erikat

Hamad

Khalifeh

2010

Physica Status Solidi (b)

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22023), Fax: þ962-6-5348932Density functional theory (DFT) calculations are performed to investigate the CO oxidation on Ir(100) surface at different CO coverages, 0.125, 0.25, and 0.5 monolayers (ML). The reaction pathway and transition state (TS) are determined using constrained minimization and nudged elastic band (NEB) methods. We found that the CO molecule is significantly more mobile toward O atoms, which causes a weakening of the O-metal bond. The increase of CO coverage leads to a decrease in the activation energy of the reaction and an increase of O a -CO distance where O coverage is kept at 0.25 ML.

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“…Using LEED IV analysis, it has been found that CO and O form sep- arated islands when CO is adsorbed on O-covered Ir(1 0 0) [41] and Pd(1 1 1) [42], which is related to the large energy difference for CO adsorption on different adsorption sites of the bare surface [42]. In STM studies of NO on O-covered Rh(1 1 1) [12], NO and O form separate islands that depend strongly on the initial adsorbate coverage and adsorption temperature.…”

Section: Discussionmentioning

confidence: 99%