Oxygen adsorbed on oxidized Ru(0001)

Böttcher, Artur; Niehus, Horst

doi:10.1103/physrevb.60.14396

Cited by 112 publications

(123 citation statements)

References 28 publications

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“…The O br /− termination is routinely observed experimentally after high temperature anneals in UHV, whereas the O br /O cus termination can be stabilized by oxygen post-exposure [10,[22][23][24]. Extensive theoretical work over the last years has shown that O and CO adsorption at other sites of the surface is energetically significantly less favorable than adsorption at bridge and cus sites [10,[23][24][25][26], which is consistent with all presently available experimental data [6,10,[27][28][29][30][31][32].…”

Section: Co Oxidation At Ruo (110)supporting

confidence: 83%

“…Practically identical activities were subsequently obtained by Peden and Goodman [4], also for the Ru(0001) single crystal surface, on which I will focus from now on. This clear manifestation of a pressure gap could be resolved by extensive experimental and theoretical work, which showed that in oxygen-rich reactive environments RuO 2 forms at the surface [5][6][7][8][9][10][11][12]. While under UHV conditions the CO oxidation therefore takes place at the inactive Ru surface, the measured high catalytic activity in ambient conditions is instead actuated by the formed oxide film [8,[12][13][14][15].…”

Section: Oxide Formation In the Reactive Environmentmentioning

confidence: 99%

“…It is important to realize that this spatial distribution is inherent to the steady-state situation under these specific gas-phase conditions. While all four terminations with defined surface structures shown in Figure 3 could recently be stabilized and characterized in UHV [6,10,27,29,31,32], the spatial distribution of the chemicals at the surface in the catalytically relevant active state is quite distinct from any of these terminations. The problem with ex situ UHV studies is obviously, that depending on the specific preparation recipe, quite different surface structures can be kinetically frozen in.…”

Section: The "Active State"mentioning

confidence: 99%

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Insight into a Pressure and Materials Gap: CO Oxidation at "Ruthenium" Catalysts

Reuter¹

2006

Oil & Gas Science and Technology - Rev. IFP

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Résumé -Impact de la pression et de l'état du matériau sur la réactivité : oxydation de CO avec des catalyseurs de « ruthénium » -Des travaux expérimentaux et théoriques récents sur l'oxydation du CO avec des catalyseurs au ruthenium offrent un apercu fascinant sur les origines microscopiques des « gouffres » des pressions et des matériaux, sujet souvent controversé entres les études réalisées dans des conditions réalistes de pression et celles réalisées sous ultravide (UHV). En se concentrant sur le catalyseur modèle Ru(0001), le système considéré présente en fait deux composants importants relatifs à ce sujet. En premier lieu, un environnement riche en oxygène transforme le matériau Ru en RuO 2 . Ainsi, des études antérieures sur la pression ambiante portant sur les catalyseurs au « ruthénium » se concentraient en fait sur un film d'oxyde formé à la surface. En second lieu, même après que le RuO 2 se soit formé, la composition de surface varie fortement selon la pression ; il faut également noter que sur le RuO 2 (110) formé, il y a une phase de surface de basse pression qui est couramment étudiée sous UHV, mais qui présente peu d'éléments en commun avec la situation où le catalyseur est actif. (0001) Abstract -Insight into a Pressure and Materials Gap: CO Oxidation at "Ruthenium" CatalystsRecent experimental and theoretical work on the CO oxidation reaction at "ruthenium" catalysts provides intriguing insight into the microscopic origins behind the frequently discussed pressure and materials gap between studies performed in ultra-high vacuum (UHV) and under realistic pressure conditions. Focusing on the Ru

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Section: Co Oxidation At Ruo (110)supporting

confidence: 83%

Section: Oxide Formation In the Reactive Environmentmentioning

confidence: 99%

Section: The "Active State"mentioning

confidence: 99%

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Insight into a Pressure and Materials Gap: CO Oxidation at "Ruthenium" Catalysts

Reuter¹

2006

Oil & Gas Science and Technology - Rev. IFP

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“…3 we present the calculated work-functions together with experimental values. References for experiments: Co [23], Ni [23], Cu [23], Ru [24,25], Rh [26], Pd [27], Ag [23], Ir [23], Pt [26,28], Au [23].…”

Section: B Work-functionmentioning

confidence: 99%

CO adsorption on close-packed transition and noble metal surfaces: trends fromab initiocalculations

Gajdoš

Eichler

Häfner

2004

J. Phys.: Condens. Matter

413

431

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We have studied the trends in CO adsorption on close-packed metal surfaces: Co, Ni, Cu from the 3d row, Ru, Rh, Pd, Ag from the 4d row and Ir, Pt, Au from the 5d row using density functional theory. In particular, we were concerned with the trends in the adsorption energy, the geometry, the vibrational properties and other parameters derived from the electronic structure of the substrate. The influence of specific changes in our setup such as choice of the exchange correlation functional, the choice of pseudopotential and size of the basis set, substrate relaxation has been carefully evaluated. We found that while the geometrical and vibrational properties of the adsorbate-substrate complex are calculated with high accuracy, the adsorption energies calculated with the gradient-corrected Perdew-Wang exchange-correlation energies are overestimated. In addition, the calculations tend to favour adsorption sites with higher coordination, resulting in the prediction of wrong adsorption sites for the Rh, Pt and Cu surfaces (hollow instead of top). The revised Perdew-Burke-Erzernhof functional (RPBE) leads to lower (i.e. more realistic) adsorption energies for transition metals, but to wrong results for noble metals -for Ag and Au endothermic adsorption is predicted. The site preference remains the same. We discuss trends in relation to the electronic structure of the substrate across the Periodic Table, summarizing the state-of-the-art of CO adsorption on close-packed metal surfaces.

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“…Recently, a mechanism was presented for the formation of an oxygen ad-layer through subsurface oxides using TDS and UPS. [7] An understanding of these initial oxide stages can be instrumental in developing methods for mitigation of oxidation in EUV lithography. XPS is a powerful technique for identifying chemical states.…”

Section: Introductionmentioning

confidence: 99%

Unraveling the oxidation of Ru using XPS

Ernst

Sloof

2008

Surface & Interface Analysis

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A method is presented to analyze XPS spectra recorded from thin (<5 nm) oxide layers with known thickness on corresponding metal substrates. With this method, the contribution of the oxide overlayer can be separated from the metal substrate for the metal core level line, even when the difference in binding energy between metallic and oxidic electrons is small. This method involves the fitting of Doniach-Sunjic (DS) line shapes for the metallic and oxidic state to the measured spectrum, where the area ratio between the metallic and oxidic contribution is fixed through the known thickness.The method was applied to ruthenium single crystals with a (0001) surface that were oxidized in a ultra-high vacuum (UHV) chamber at a temperature of 673 K and an oxygen pressure between 1×10 −4 and 1×10 −2 Pa. Analysis of the oxidic contribution to the Ru 3p 3/2 line shows that two different types of oxides can be formed in the oxidation process.

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Oxygen adsorbed on oxidized Ru(0001)

Cited by 112 publications

References 28 publications

Insight into a Pressure and Materials Gap: CO Oxidation at "Ruthenium" Catalysts

Insight into a Pressure and Materials Gap: CO Oxidation at "Ruthenium" Catalysts

CO adsorption on close-packed transition and noble metal surfaces: trends fromab initiocalculations

Unraveling the oxidation of Ru using XPS

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