Identification of Subsurface Oxygen Species Created during Oxidation of Ru(0001)

Blume, Raoul; Niehus, Horst; Conrad, H.; Böttcher, Artur; Aballe, Lucía; Gregoratti, Luca; Barinov, A.; Кискинова, М.

doi:10.1021/jp044175x

Cited by 76 publications

(116 citation statements)

References 24 publications

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“…When the total amount of adsorbed and incorporated oxygen exceeds ~ 3 ML a new broad component at ~ 0.4 eV, Ru x O y , grows. It corresponds to the most advanced oxidation state below 500 K with a poorly-defined structure and thickness of about two rutile layers (5-6 Ǻ) [21]. Although the energy position of the Ru x O y component is practically identical with the Ru(I)-2O ad one, the Ru 3d spectra are very different, because of the strong attenuation of Ru bulk component due to screening by the 'surface oxide' film.…”

Section: Resultsmentioning

confidence: 99%

“…They undergo distinct chemical shifts when binding to O, determined by the coordination number of O atoms and their bonding configuration [4,25]. The incorporation of O subsurface, O sub , leads to a distinct shift of Ru(II) resulting in the component Ru(II)-O sub at ~ 0.5 eV, well separated from the Ru bulk position [21]. The Ru(I) energy shift induced by the subsurface oxygen accounts for the Ru(I)-2O ad O sub and Ru(I)-3O ad O sub components at ~0.8 and 1.3 eV, assigned to Ru(I) atom coordinated with 2 or 3 O adatoms, respectively, and subsurface oxygen below.…”

Section: Resultsmentioning

confidence: 99%

“…1 shows schematically the 'oxidation' states of the Ru(0001) that have attained experimental proof [2,4,13,14,21] In the following we will call them: adsorption phase, referring the state when oxygen in present only on the surface with maximum coverage 1 ML (A), 'surface oxide' with ~ 1-3 ML oxygen incorporated within the top few Ru layers (B and C) and rutile RuO 2 phase (D). An important finding of XPS microscopy is that 'surface oxide' and RuO 2 phases coexist in a wide T-pressure range, even when formed in a pure O 2 ambient [13,21] Undoubtedly under reaction conditions, the CO will drive the oxidation state away from the equilibrium achieved in O 2 ambient, which implies that the T-p space of coexistence of the two phases may be expanded.…”

Section: Figurementioning

confidence: 99%

“…The conversion into a RuO 2 (110) structure is supposed to occur above the critical thickness of two O-Ru-O trilayers (oxygen content of 4 ML). Spectroscopic evidence for subsurface oxygen species has been provided by photoelectron diffraction and combined photoemission and thermal desorption spectroscopy [20,21] according to another model, based on investigations of Ru oxidation carried out at T > 600 K, the RuO 2 nucleus is formed as far as the oxygen exceeds 1 ML, the coverage of the most dense (1x1) adsorption phase, and the RuO 2 (110) film grows progressively in autocatalytic manner [10,22].…”

Section: Introductionmentioning

confidence: 99%

“…The recent XPS microscopy and TDS studies demonstrated that starting from an atomically clean Ru(0001) surface, the formation of a stoichiometric RuO 2 phase is kinetically hindered at temperatures lower than 500 K and readily occurs at higher temperatures [2,13,14,21]. The main reason for such temperature dependence of the Ru oxidation state is that the incorporation up to 3 ML of oxygen at T < 500 K is limited to the top 2-3 Ru layers.…”

Section: Introductionmentioning

confidence: 99%

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Catalytically active states of Ru(0001) catalyst in CO oxidation reaction

Blume

Hävecker

Zafeiratos

et al. 2006

Journal of Catalysis

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Identifying the composition of the catalytically active state of metal catalysts under dynamic operating conditions is of particular importance for oxidation catalysis. We report here new insights into the chemical identity of different catalytically active states formed on a Ru(0001) catalyst during the CO oxidation at different reaction temperatures. The changes in the surface composition of the Ru catalyst and the CO 2 yield under varying reaction conditions in the 10 -4 to 10 -1 mbar pressure range were followed in-situ by synchrotron-based high-pressure x-ray photoelectron spectroscopy and mass spectroscopy. The obtained results reveal that the catalytic activity of a few layers thick 'surface oxide' without well defined stoichiometry and structure is comparable with the activity of the stoichiometric RuO 2 (110) phase. The 'surface oxide' forms under reaction conditions when the formation of the RuO 2 is kinetically hindered, and can coexist with RuO 2 in a wide temperature-pressure range.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Figurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Catalytically active states of Ru(0001) catalyst in CO oxidation reaction

Blume

Hävecker

Zafeiratos

et al. 2006

Journal of Catalysis

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Flexible Ru/Graphene Aerogel with Switchable Surface Chemistry: Highly Efficient Catalyst for Room‐Temperature CO Oxidation

Zhang

Wang

et al. 2016

Adv Materials Inter

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such as direct crosslinking of the GO suspension, [ 7 ] chemical reduction, [ 8,9 ] hydrothermal assembly, [ 10,11 ] ice-templateguided assembly, [ 12 ] organic sol-gel chemistry, [ 13 ] have been developed to assemble porous 3D graphene aerogels. These 3D aerogels could provide graphene materials with high surface areas, and strong or fl exible mechanical properties.Functionalization of 3D graphene aerogels are generally required to offset the drawbacks of pure graphene in the specifi c desired functionality. Utilizing an in situ chemical or hydrothermal reduction, functional metal/metal oxide nanoparticles could be directly decorated onto the graphene sheets during 3D network formation. [14][15][16] The large accessible surface area together with the open macropore structure enables graphene aerogels to effectively host fi nely dispersed nanoparticles, to provide nanoparticle accessibility, as well as to provide paths for the easy access and diffusion of molecules. [ 16 ] In addition, the oxygen-containing functional groups on GO would facilitate the effective linking between graphene and nanoparticles, which may contribute to the synergistic effects, such as modifying chemical and electronic structure of the active metal. [ 17 ] Thus, this is an ideal strategy for developing high-performance heterogeneous catalysts. Recently, many metal oxide nanoparticles such as FeO x , [17][18][19] MnO x , [ 20,21 ] TiO 2 , [ 22 ] Co 3 O 4[ 23 ] could be incorporated into the graphene network during the reduction and self-assembly of GO sheets. And in some cases, the noble metal (Pt, Au, or Ag) nanoparticles could be also in situ incorporated into the 3D graphene aerogels for potential catalytic applications. For example, Wang et al. [ 24 ] demonstrated a hydrothermal assembly of GO into 3D aerogel promoted by a noble-metal nanocrystal, and the resulting composites exhibited excellent catalytic activity and selectivity for the Heck reaction. Here the glucose was used as the reduce agent, which promoted the formation of noble-metal nanocrystal. Ren et al. [ 25 ] reported a hydrothermal reduction of GO and Ni ions using N 2 H 4 as the reduction regent, which could obtain metallic nickel nanoparticle/graphene aerogel with high electrocatalytic properties for ethanol oxidation. Li et al. [ 26 ] described a hydrothermal self-assembly to obtain Au/graphene hydrogels using Self-assembly and functionalization of macroscopic graphene architectures are generally required to offset the drawbacks of pure graphene sheets for practical applications. Herein, a macroscopic 3D fl exible well-faceted Ru nanocrystalline-decorated graphene aerogel is prepared by a unique poly ol-mediated solvothermal method. The key to the synthesis is relied on ethylene glycol as the solvent and reducing agent, which can simultaneously reduce graphene oxide (GO) and Ru 3+ ions and further self-assemble into the 3D aerogel network. The resultant Ru/graphene aerogels possess a low density of 17.3 mg cm −3 , highly porous structures, good fl exible ability, and ...

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Die CO‐Oxidation als Modellreaktion für heterogene Prozesse

et al. 2011

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Die CO‐Oxidation, obwohl eine scheinbar einfache chemische Reaktion, dient als ein Modell, welches die Vielfalt und Attraktivität der heterogenen Katalyse offenbart. Das Fritz‐Haber‐Institut ist ein Ort, an dem ein multidisziplinärer Forschungsansatz zum Studium einer solchen heterogenen Reaktion innerhalb eines Instituts entwickelt und umgesetzt werden kann. Dabei ist die Forschung am Institut primär durch Neugier getrieben, was sich auch in den fünf Abschnitten dieses Aufsatzes widerspiegelt. Wir nutzen dabei mikroskopische Konzepte, um die Wechselwirkung einfacher Moleküle mit wohldefinierten Materialien wie Clustern in der Gasphase oder festen Oberflächen zu untersuchen. Dieser Ansatz erfordert nicht selten die Entwicklung von neuen Methoden, Werkzeugen und Materialien zur Verifizierung dieser Konzepte, und dies ermöglicht eine methodologisch solide, breit aufgestellte Herangehensweise als ein Markenzeichen des Instituts.

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Identification of Subsurface Oxygen Species Created during Oxidation of Ru(0001)

Cited by 76 publications

References 24 publications

Catalytically active states of Ru(0001) catalyst in CO oxidation reaction

Catalytically active states of Ru(0001) catalyst in CO oxidation reaction

Flexible Ru/Graphene Aerogel with Switchable Surface Chemistry: Highly Efficient Catalyst for Room‐Temperature CO Oxidation

Die CO‐Oxidation als Modellreaktion für heterogene Prozesse

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