Carbonate formation on the O-enriched RuO2(110) surface

Lafosse, A.; Wang, Yuemin; Jacobi, K.

doi:10.1063/1.1490339

Cited by 26 publications

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“…The energy needed for these relaxations is compensated, to a large extent, by the energy gained from forming two additional ZnÀO bonds, so that the binding energy of the tridentate species is, in fact, comparable to that of monodentate carbonate species, for example, on RuO 2 (110). [20,21] The same CO 2 adsorption geometry was also found in the quantum-chemical cluster calculations. An analysis of the charge distribution and of the O1s core levels reveals a significant charge transfer to the O atoms of the adsorbed CO 2 molecule and confirms that a negatively charged carbonate ion is indeed formed upon CO 2 adsorption.…”

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confidence: 51%

“…Interestingly, the vibrational spectra for the a and b states are very similar. The HREELS data in Figure 4 show frequencies typical for carbonate species: [20,21] an out-of-plane deformation mode p(CO 3 ) at 839 cm À1 and the three CÀO stretching modes at 994, 1340, and 1615 cm À1 . To unambiguously identify the vibrations arising from CO 3 dÀ species, measurements were carried out by exposing ZnO (101 0) Figure 3) containing only weakly bound CO 2 species.…”

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confidence: 98%

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CO₂ Activation by ZnO through the Formation of an Unusual Tridentate Surface Carbonate

et al. 2007

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The activation of CO 2 is one of the most important topics in catalysis.[1] For example, one of the simple Zn-enzymecatalyzed processes, the hydration of CO 2 by carbonic anhydrase, has led to extensive mechanistic and theoretical studies of the interaction of CO 2 with Zn-OH. [2][3][4][5] Also, in heterogeneous catalysis, a detailed understanding of the surface chemistry of CO 2 is an important issue; interest in this topic ranges from developing new processes for an emplacement of this greenhouse gas to the synthesis of methanol from syngas (CO/CO 2 /H 2 ) over Cu/ZnO catalysts. [6] Numerous studies have been reported on CO 2 adsorption on clean metal surfaces, where frequently activation is found to occur via the formation of a bent CO 2 dÀ species. [7][8][9] For oxide surfaces much less information is available. This deficit is in part due to the poor electric conductivity of many oxides which severely complicates the application of electron-based spectroscopic methods. In particular, there is a lack of information concerning molecular vibrations from highresolution electron energy loss spectroscopy (HREELS).The application of HREELS on oxide surfaces is-in addition to the electric conductivity problem-severely limited by the presence of intense substrate lattice excitations (FuchsKliewer phonons [10] ) which obscure the relatively weak vibrational modes of adsorbed species.Herein we present the results of a systematic multitechnique experimental and theoretical study on the interaction of CO 2 with the mixed-terminated ZnO(101 0) surface. In contrast to other oxides, ZnO is sufficiently conductive that electron-based methods can be applied without significant difficulties. The results from HREELS, thermal desorption spectroscopy (TDS), low-energy electron diffraction (LEED), He-atom scattering (HAS), and X-ray photoelectron spectroscopy (XPS) reveal a complicated scenario, comprising the presence of two different ordered phases. By employing accurate periodic density-functional theory (DFT) and wave-function-based quantum-chemical cluster calculations it could be shown that the previously proposed bidentate bonding of CO 2 to this ZnO surface [11] has to be revised. Exposure to CO 2 leads-even at temperatures below 100 Kto the formation of an unusual tridentate carbonate species with the two O atoms of the CO 2 molecule being almost equivalently bound to two different Zn surface atoms.In a first set of experiments, the phase diagram of CO 2 adlayers on this ZnO substrate was determined using HAS. This technique uses neutral He atoms with thermal energy so charging problems are avoided. HAS is a highly sensitive surface-analysis method, [12][13][14] and has been successfully used to determine the phase diagram of H 2 O on the same surface.[15] The HAS data show that exposure of the sample to very small amounts of CO 2 in two steps (first with 4 L at 260 K and then 8 L at 120 K; exposures are given in units of langmuir (1 L = 1.33 10 À6 mbar s)) results in the formation of a well-ordered (2 1) phase (Figure 1 ...

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CO₂ Activation by ZnO through the Formation of an Unusual Tridentate Surface Carbonate

et al. 2007

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“…Additional features observed at 58, 110, 230, 436, and 447 meV increase with collection time of the spectra. These peaks are normally observed when analyzing RuO 2 (110) surfaces at low temperatures [8][9][10][11] and can be ascribed to a H 2 O-like species (H 2 O-bridge) formed through interaction of H 2 from the background with O-bridge [12]. A detailed assignment of all peaks to vibrational modes of adsorbed CH 4 (CD 4 ) will be given in Sect.…”

Section: Tds and Hreels Of Methanementioning

confidence: 99%

“…This surface is called O-rich RuO 2 (110). The O-cus species is relatively weakly bound on the surface and desorbs at temperatures as low as 400-500 K. Therefore, this species is expected to be very reactive as verified, e.g., by CO oxidation [4,6], carbonate formation [8,9], ethylene oxidation [10], and ammonia oxidation [11].…”

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Adsorption of Methane and Ethane on RuO₂(110) Surfaces

Erlekam¹,

Paulus²,

Wang³

et al. 2005

Zeitschrift Für Physikalische Chemie

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The adsorption of methane and ethane on the stoichiometric and O-rich RuO 2 (110) surfaces, respectively, was studied by thermal desorption and high-resolution electron energy loss spectroscopy. The results support weak adsorption (physisorption) of these molecules on the surface, regardless of the presence of undercoordinated Ru and oxygen surface sites. The vibrational spectra recorded at about 90 K are compared with spectra calculated for gaseous CH 4 and C 2 H 6 . The nearly complete agreement of frequencies and relative intensities is consistent with physisorption. No evidence of adsorption induced molecule activation is found.

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CO₂‐Aktivierung durch ZnO unter Bildung eines ungewöhnlichen dreizähnigen Oberflächencarbonats

et al. 2007

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Die Aktivierung von CO 2 ist eines der wichtigsten Themen in der Katalyse.[1] So wurden zum Beispiel zur Hydratation von CO 2 durch Carboanhydrase, einem der einfachen durch Zinkenzyme katalysierten Prozesse, umfangreiche mechanistische und theoretische Studien durchgeführt, speziell zur Wechselwirkung von CO 2 mit ZnÀOH. [2][3][4][5] Auch in der heterogenen Katalyse ist ein grundlegendes Verständnis der Oberflächenchemie von CO 2 von großer Bedeutung; das Interesse reicht von der Entwicklung neuer Prozesse für eine Einlagerung dieses Treibhausgases bis zur Methanolsynthese aus Synthesegas (CO/CO 2 /H 2 ) über Cu/ZnO-Katalysatoren. [6] Frühere Untersuchungen zur CO 2 -Adsorption konzentrierten sich auf saubere Metalloberflächen, auf denen in der Regel eine CO 2 -Aktivierung über die Bildung einer gewinkelten CO 2 dÀ -Spezies erfolgt. [7][8][9] In einer ersten Serie von Experimenten wurde das Phasendiagramm der CO 2 -Adsorbatlagen auf diesem ZnO-Substrat mithilfe von HAS untersucht. Bei dieser Technik werden neutrale He-Atome mit thermischer Energie verwendet, sodass grundsätzlich keine Aufladungsprobleme auftreten. Diese außerordentlich empfindliche Oberflächenanalysen-methode [12][13][14] wurde bereits erfolgreich in früheren Untersuchungen zur Bestimmung des Phasendiagramms von H 2 O auf derselben Oberfläche eingesetzt.[15] Die HAS-Daten zeigen, dass sich nach Belegen der Probe mit einer sehr kleinen CO 2 -Menge in zwei Schritten (zuerst mit 4 L bei 260 K und dann 8 L bei 120 K) eine gut geordnete (2 1)-Phase bildet (Abbildung 1, Kurve b). Nach Sättigung der Oberfläche mit CO 2 verschwindet diese (2 1)-Struktur, und eine (1 1)

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Carbonate formation on the O-enriched RuO2(110) surface

Cited by 26 publications

References 28 publications

CO₂ Activation by ZnO through the Formation of an Unusual Tridentate Surface Carbonate

CO₂ Activation by ZnO through the Formation of an Unusual Tridentate Surface Carbonate

Adsorption of Methane and Ethane on RuO₂(110) Surfaces

CO₂‐Aktivierung durch ZnO unter Bildung eines ungewöhnlichen dreizähnigen Oberflächencarbonats

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Carbonate formation on the O-enriched RuO2(110) surface

Cited by 26 publications

References 28 publications

CO2 Activation by ZnO through the Formation of an Unusual Tridentate Surface Carbonate

CO2 Activation by ZnO through the Formation of an Unusual Tridentate Surface Carbonate

Adsorption of Methane and Ethane on RuO2(110) Surfaces

CO2‐Aktivierung durch ZnO unter Bildung eines ungewöhnlichen dreizähnigen Oberflächencarbonats

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CO₂ Activation by ZnO through the Formation of an Unusual Tridentate Surface Carbonate

CO₂ Activation by ZnO through the Formation of an Unusual Tridentate Surface Carbonate

Adsorption of Methane and Ethane on RuO₂(110) Surfaces

CO₂‐Aktivierung durch ZnO unter Bildung eines ungewöhnlichen dreizähnigen Oberflächencarbonats