Adsorption of acetylene and hydrogen on Pd(111): formation of a well-ordered ethylidyne overlayer

Sandell, A.; Beutler, Andreas S.; Jaworowski, A.J; Wiklund, M; Heister, K.; Nyholm, R.; Andersen, Jesper N

doi:10.1016/s0039-6028(98)00602-5

Cited by 38 publications

(34 citation statements)

References 31 publications

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“…The problem here is not only that the substrate Pd 3p 3/2 component is intense (and shows strong PhD modulations in intensity), but this substrate emission itself is expected to comprise at least two distinct components associated with emission from the surface and subsurface ('bulk') atoms (like the Pd 3d 3/2 peak [15]). Moreover, previous detailed studies of the Pd 3d spectrum indicate that adsorption may lead to chemical shifts in the surface component(s) [15], so using the clean surface spectra as a means of subtracting the Pd component to extract the O 1s component are also unlikely to be reliable. After exhaustive efforts to effect the separation in a range of different ways we finally concluded that it was not possible to extract meaningful O 1s PhD modulation spectra from the recorded data.…”

Section: Experimental Details and Surface Characterisationmentioning

confidence: 99%

The adsorption structure of furan on Pd(111)

et al. 2008

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The structure of molecular furan, C 4 H 4 O, on Pd(111) has been investigated by O K-edge near-edge X-ray absorption fine structure (NEXAFS) and C 1s scanned-energy mode photoelectron diffraction (PhD). NEXAFS shows the molecule to be adsorbed with the molecular plane close to parallel to the surface, a conclusion confirmed by the PhD analysis. Chemical-state specific C 1s PhD data were obtained for the two inequivalent C atoms in the furan, the α-C atoms adjacent to the O atom, and the β-C atoms bonded only to C atoms, but only the PhD modulations for the α-C emitters were of sufficiently large amplitude for detailed evaluation using multiple scattering calculations. This analysis shows the α-C atoms to be located approximately 0.6 Å off-atop surface Pd atoms with an associated C-Pd bondlength of 2.13±0.03 Å. Two alternative local geometries consistent with the data place the O atom in off-atop or near-hollow locations, and for each of these local structures there are two equally-possible registries relative to the fcc and hcp hollow sites. The results are in good agreement with earlier density functional theory calculations which indicate that the fcc and hcp registries are equally probable, but the PhD results fail to distinguish the two distinct local bonding geometries.

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Section: Experimental Details and Surface Characterisationmentioning

confidence: 99%

The adsorption structure of furan on Pd(111)

et al. 2008

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“…Palladium is one of the most important hydrogenation catalysts, widely employed in industrial processes [1][2][3][4][5][6][7] but also in basic research [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Its practical importance in the interaction with various gases has stimulated widespreading investigations from the point of view of catalytic [8][9][10][11][12]14,15,17] and surface properties [13,16,[18][19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

“…Its practical importance in the interaction with various gases has stimulated widespreading investigations from the point of view of catalytic [8][9][10][11][12]14,15,17] and surface properties [13,16,[18][19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

High-pressure X-ray photoelectron spectroscopy of palladium model hydrogenation catalysts.Part 1: Effect of gas ambient and temperature

Teschner

Pestryakov

Kleimenov

et al. 2005

Journal of Catalysis

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In light of accumulating evidences highlighting the major role of operational conditions (gas composition, pressure, temperature) on the surface/bulk structure of catalytic materials, their characterization should involve more and more in-situ methods. We constructed a synchrotronbased high-pressure XPS (X-ray photoelectron spectroscopic) instrument, allowing us to investigate the surface and near-surface state of a catalyst in the mbar pressure range. We discuss here the surface characteristics of palladium samples as a function of gas-phase (hydrogen, oxygen) and temperature. We demonstrate that the surface region of catalytic materials behaves dynamically in its composition, always reflecting on its environment. For example, surface oxide can be formed on Pd(111) in oxygen which decomposes rapidly as the gas supply is switched off. The chemical nature of carbonaceous deposits depends also strongly on the operational conditions (gas-phase hydrogen, temperature). It is the first time that XPS investigation on palladium β-hydride was performed at RT. The possible drawbacks of using non-UHV setup e.g. fast carbon accumulation are also discussed.

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“…Palladium, as one of the Group 8 metals, is widely employed in industrial processes [1][2][3][4][5][6][7] but also in basic research [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23] mainly as a hydrogenation catalyst. Its interaction with various gases has been extensively investigated with regard to its catalytic [8][9][10][11][12]14,15,17] and surface properties [13,16,[18][19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

High-pressure X-ray photoelectron spectroscopy of palladium model hydrogenation catalysts. Part 2: Hydrogenation of trans-2-pentene on palladium

Teschner

Pestryakov

Kleimenov

et al. 2005

Journal of Catalysis

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We have performed the first "high-pressure" XPS study on the palladium, hydrogen and olefin (trans-2-pentene) system in order to gain a better insight into the hydrogenation reaction. We report here data collected using a Pd(111) single crystal and a polycrystalline foil. Hydrogenation was observed on polycrystalline foil (RT and 373 K), but not on Pd(111) single crystal, revealed by on-line mass-spectrometry. We observed the reaction in the presence of huge amount of carbon (up to 73 %) in the information depth of XPS. On Pd(111) mainly graphite was present while other components C-H and C-Pd were also formed on the foil in much higher extent. C-Pd characterizes a carbon species in the interaction with palladium whereas C-H represents hydrogenated carbon including chemisorbed species. The d-band of the foil showed a remarkable up-shift towards E FERMI as compared to Pd(111). We concluded that both differences found in the valence and in C 1s region are indicators for different electronic structures that contribute to the variation in activity. The palladium foil lost its activity at elevated temperature (523 K), most probably due to desorption of hydrogen. Using additional UPS measurements we concluded that trans-2-pentene is hydrogenated in σ-bonded chemisorption modus, at least in UHV conditions.

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Adsorption of acetylene and hydrogen on Pd(111): formation of a well-ordered ethylidyne overlayer

Cited by 38 publications

References 31 publications

The adsorption structure of furan on Pd(111)

The adsorption structure of furan on Pd(111)

High-pressure X-ray photoelectron spectroscopy of palladium model hydrogenation catalysts.Part 1: Effect of gas ambient and temperature

High-pressure X-ray photoelectron spectroscopy of palladium model hydrogenation catalysts. Part 2: Hydrogenation of trans-2-pentene on palladium

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