Interaction of H2O with Co(112¯0): a photoelectron spectroscopic study

Grellner, F.; Klingenberg, B.; Borgmann, D.; Wedler, G.

doi:10.1016/0039-6028(94)90811-7

Cited by 18 publications

(15 citation statements)

References 17 publications

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“…With increasing H 2 O exposure, the desorption peak grows continually and does not saturate, indicative of desorption from a H 2 O multilayer; meanwhile, the peak maximum shifts to higher temperature, characteristic of zero-order desorption kinetics. It was reported that surface hydroxyls formed by H 2 O dissociation on Co(112̅0) recombine to produce H 2 O above 270 K . The observed TDS features are similar to those for H 2 O adsorption on coinage metal single-crystal surfaces, – in which the H 2 O−H 2 O interaction is stronger than the H 2 O−metal interaction and the adsorption of H 2 O is nonwetting, forming intact and 3D H 2 O(a) islands.…”

Section: Resultssupporting

confidence: 55%

Water Adsorption on a Co(0001) Surface

Zhang

et al. 2010

J. Phys. Chem. C

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We have investigated the adsorption of water on a Co(0001) surface by means of temperature-programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS), and low-energy electron diffraction (LEED). At 130 K, the interaction between adsorbed water (H 2 O(a)) and Co(0001) is quite weak, and water adsorption forms an intact, nonwetting, and three-dimensional layer on Co(0001). The monolayer and multilayer of H 2 O(a) could be distinguished by XPS, and they desorb molecularly upon heating but only giving a single water desorption peak. An ordered p(2 × 2) LEED pattern was observed at low exposures of water. At room temperature, water adsorbs dissociatively on Co(0001), forming chemisorbed atomic oxygen (O(a)) and atomic hydrogen (H(a)). Upon heating, H(a) recombines into H 2 desorbing from the surface, whereas O(a) remains on the surface. The interaction of water with Co( 0001) is greatly influenced by the presence and nature of the oxygen species on Co(0001). Water adsorption on Co(0001) precovered with 0.45 ML O(a) at 130 K forms a mixture layer of OH(a) and H(a) via the reaction of 2H 2 O(a) + O(a) f 3OH(a) + H(a). However, on oxide-like Co(0001) surface, the water decomposition is completely passivated even at room temperature. These results broaden our fundamental understanding of water interaction with metal surfaces and provide insights into the water-involved catalytic reactions catalyzed by cobalt. † Part of the "D. Wayne Goodman Festschrift".

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Section: Resultssupporting

confidence: 55%

Water Adsorption on a Co(0001) Surface

Zhang

et al. 2010

J. Phys. Chem. C

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“…Experimental information can be obtained from the combination of various experimental techniques, such as low-energy electron diffraction (LEED), scanning-tunneling microscopy (STM), or reflection–absorption IR spectroscopy (RAIRS). The number of studies on the interaction of water with cobalt surfaces, while of fundamental interest for important industrial processes such as the Fischer–Tropsch synthesis, has thus far been limited; they indicate that water binds molecularly to most smooth crystalline surfaces but dissociates on defect sites. − …”

Section: Introductionmentioning

confidence: 99%

Water Adsorption on Free Cobalt Cluster Cations

et al. 2015

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Cationic cobalt clusters complexed with water Con(+)-H2O (n = 6-20) are produced through laser ablation and investigated via infrared multiple photon dissociation (IR-MPD) spectroscopy in the 200-1700 cm(-1) spectral range. All spectra exhibit a resonance close to the 1595 cm(-1) frequency of the free water bending vibration, indicating that the water molecule remains intact upon adsorption. For n = 6, the frequency of this band is blue-shifted, but it gradually converges to the free water value with increasing cluster size. In the lower-frequency range (200-650 cm(-1)) the spectra contain several bands which show a very regular frequency evolution, suggesting that the exact cluster geometry has little effect on the water-surface interaction. Density functional theory (DFT) calculations are carried out at the OPBE/TZP level for three representative sizes (n = 6, 9, 13) and indicate that the vibrations responsible for the resonances correspond to bending and torsional modes between the cluster and water moieties. The potential energy surfaces describing these interactions are very shallow, making the calculated harmonic frequencies and IR intensities very sensitive to small geometrical perturbations. We conclude that harmonic frequency calculations on (local) minima structures provide insufficient information for these types of cluster complexes and need to be complemented with calculations that provide a more extensive sampling of the potential energy surface.

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“…1 ML of Pd adsorbed on Nb͑001͒ exhibits energetically deep lying emissions like the noble-metal Cu, 55 whereas thicker Pd films display only a strong UPS peak just below the Fermi level like the ferromagnetic metals Ni ͑Ref. 56͒ and Co. 33,[57][58][59][60] The aim of this work is to determine the properties of the Pd layers exhibiting the unusual UPS emissions, i.e., of 1 ML Pd deposited on Nb͑001͒ and of thick Pd films grown on this substrate. To this end their geometric and electronic structure will be determined using electron diffraction and electron spectroscopy measurements.…”

Section: Resultsmentioning

confidence: 99%

“…A ͑1120͒-oriented bulk sample of Co also shows in UPS only an emission near the Fermi energy. [58][59][60] Similarly, a strong UPS emission at the Fermi edge is characteristic of ͑1120͒-oriented Ni films. 56,77 It should be pointed out, however, that the same crystal structure does not necessarily lead to the same UPS emissions.…”

Section: Arups From Hcp Pd Films In Comparison To Ups From Co and Ni mentioning

confidence: 95%

“…III B 3͒, similar ARUPS emissions ͑i.e., a single, strong peak close to the Fermi level͒ were obtained from ͑1120͒-oriented, ferromagnetically ordered hcp Ni ͑Refs. 56 and 77͒ and hcp Co. 33,[57][58][59][60] The UPS intensity curve related to the flat E͑k ʈ ͒ band situated close to the Fermi level of ͑1120͒-oriented hcp Co films grown on W͑001͒ ͓Fig. 24͑b͔͒ is marked with circles in Fig.…”

Section: Nonmagnetic Arups Measurementsindication Of Ferromagnetic Ormentioning

confidence: 99%

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Pd bonded on Nb(001): Dependence of noble metal and ferromagnetic characteristics on film thickness

Hüger

Osuch

2005

Phys. Rev. B

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Experimental observations confirmed by density functional theory ͑DFT͒ calculations show that strong epitaxial bonds between Pd atoms and the substrate can induce two competing properties: nobleness and ferromagnetic order in the same material, i.e., Pd bonded on Nb͑100͒. Angle-resolved ultraviolet photoelectron spectroscopy measurements, confirmed by first principles, self-consistent DFT calculations show that the strong, direct bonds between a Pd monolayer and Nb͑001͒ push the d-band center of the monolayer toward lower binding energies, which results in the Pd reactivity comparable to that of the noble metal Ag. The strong epitaxial constraint of the Nb͑001͒ substrate induces a ͑1120͒-oriented hexagonal close-packed structure in thicker Pd films. First principles, self-consistent DFT calculations with spin-orbit coupling included performed at 0 K show that Pd in this structure is ferromagnetically ordered at the optimum lattice constant. Its bands at the Fermi level are flatter in comparison to those of Pd in its natural, nonmagnetic, face-centered-cubic structure, leading to the density of states ͑DOS͒ at the Fermi level which fulfills the Stoner criterion for ferromagnetism. We identify these bands in the bulk band structure and probe them with angle-resolved ultraviolet photoelectron spectroscopy in ͑1120͒-oriented hexagonal close-packed Pd films.

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Interaction of H2O with Co(112¯0): a photoelectron spectroscopic study

Cited by 18 publications

References 17 publications

Water Adsorption on a Co(0001) Surface

Water Adsorption on a Co(0001) Surface

Water Adsorption on Free Cobalt Cluster Cations

Pd bonded on Nb(001): Dependence of noble metal and ferromagnetic characteristics on film thickness

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