Metallicity of Ultrathin Metal Layers

Gomer, R.

doi:10.1021/ar950219w

Cited by 12 publications

(8 citation statements)

References 32 publications

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“…Our Φ results are in a good agreement with previous theoretical and experimental results. ,− ,− For Ru(0001), Pd(111), Ag(111), Pt(111), and Au(111), the work function error is less than 1% compared with previous PBE results, ,, while for other systems the deviation is about 1.9–3.2%, , except for Co(0001), where we found a deviation of about 9.5% . In general, our results are smaller than the experimental values. , The smallest deviation (about 0.5%) is obtained for Pt(111), while for the remaining systems the deviation is about 3.5–6.6%, , which have been attributed to the large error bar among the experimental results …”

Section: Resultssupporting

confidence: 89%

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Ethanol and Water Adsorption on Close-Packed 3d, 4d, and 5d Transition-Metal Surfaces: A Density Functional Theory Investigation with van der Waals Correction

2012

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Nowadays, there is a great interest in the economic success of direct-ethanol fuel cells; however, our atomistic understanding of the designing of stable and low-cost catalysts for the steam reforming of ethanol is still far from satisfactory, in particular due to the large number of undesirable intermediates. In this study, we will report a first-principles investigation of the adsorption properties of ethanol and water at low coverage on close-packed transition-metal (TM) surfaces, namely, Fe(110), Co(0001), Ni(111), Cu(111), Ru(0001), Rh(111), Pd(111), Ag(111), Os(0001), Ir(111), Pt(111), and Au(111), employing density functional theory (DFT) calculations. We employed the generalized gradient approximation with the formulation proposed by Perdew, Burke, and Erzenholf (PBE) to the exchange-correlation functional and the empirical correction proposed by S. Grimme (DFT+D3) for the van der Waals correction. We found that both adsorbates binds preferentially near or on the on-top sites of the TM surfaces through the O atoms. The PBE adsorption energies of ethanol and water decreases almost linearly with the increased occupation of the 4d and 5dd-band, while there is a deviation for the 3d systems. The van der Waals correction affects the linear behavior and increases the adsorption energy for both adsorbates, which is expected as the van der Waals energy due to the correlation effects is strongly underestimated by DFT-PBE for weak interacting systems. The geometric parameters for water/TM are not affected by the van der Waals correction, i.e., both DFT and DFT+D3 yield an almost parallel orientation for water on the TM surfaces; however, DFT+D3 changes drastically the ethanol orientation. For example, DFT yields an almost perpendicular orientation of the C–C bond to the TM surface, while the C–C bond is almost parallel to the surface using DFT+D3 for all systems, except for ethanol/Fe(110). Thus, the van der Waals correction decreases the distance of the C atoms to the TM surfaces, which might contribute to break the C–C bond. The work function decreases upon the adsorption of ethanol and water, and both follow the same trends, however, with different magnitude (larger for ethanol/TM) due to the weak binding of water to the surface. The electron density increases mainly in the region between the topmost layer and the adsorbates, which explains the reduction of the substrate work function.

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Section: Resultssupporting

confidence: 89%

“… a Reference ; DFT-GGA result. b Reference ; DFT-PW91 result. c Reference ; experiment. d Reference ; experiment. e Reference ; DFT-GGA result. f Reference ; DFT-GGA result. g Reference ; DFT-GGA result. h Reference ; DFT-GGA result. …”

Section: Resultsmentioning

confidence: 99%

Ethanol and Water Adsorption on Close-Packed 3d, 4d, and 5d Transition-Metal Surfaces: A Density Functional Theory Investigation with van der Waals Correction

2012

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“…⌽ Pd͑111͒ = 5.66, 5.25, and 5.31 eV for LDA, GGA-PBE, and GGA-PW91, respectively, while the experimental results are 5.44 eV, 59 5.55 eV, 60 and 5.95 eV. 2 The experimental and calculated results for ⌽ Pd͑111͒ are discussed in detail elsewhere.…”

Section: Work Function Change and Induced Surface Dipole Momentmentioning

confidence: 99%

Trends in adsorption of noble gases He, Ne, Ar, Kr, and Xe onPd(111)(3×3)R30°: All-electron

Silva

Stampfl

2008

Phys. Rev. B

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It was recently found from ab initio investigations ͓J. L. F. Da Silva et al., Phys. Rev. Lett. 90, 066104 ͑2003͔͒ that polarization effects and the site dependence of the Pauli repulsion largely dictate the nature of the interaction and the site preference of Xe adatoms on close-packed metal surfaces. It is unclear if the same interaction mechanism occurs for all rare-gas atoms adsorbed on such surfaces. To address this question, we perform all-electron density-functional theory calculations with the local-density approximation ͑LDA͒ and generalized gradient approximations ͑GGA͒ for ͓He, Ne, Ar, Kr, and Xe͔ / Pd͑111͒ in the ͑ ͱ 3 ϫ ͱ 3͒R30°s tructure. Our results confirm that polarization effects of the rare-gas adatoms and Pd atoms in the topmost surface layer, together with the site-dependent Pauli repulsion, largely determine the interaction between rare-gas atoms and the Pd͑111͒ surface. Similar to the earlier ab initio study, the on-top site preference is obtained by the LDA for all rare-gas adatoms, while the GGA functionals yield the on-top site preference for Xe, Kr, and He adatoms, but the fcc site for Ne and Ar.

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“…The agreement with experiment are satisfactory, taking into account the uncertainties in the measurements. [58][59][60][61][62][63]…”

Section: Clean Surfacesmentioning

confidence: 99%

Theory of nitride oxide adsorption on transition metal (111) surfaces: a first-principles investigation

Zeng

Silva

2010

Phys. Chem. Chem. Phys.

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In this work, we report a density functional theory study of nitric oxide (NO) adsorption on close-packed transition metal (TM) Rh(111), Ir(111), Pd(111) and Pt(111) surfaces in terms of adsorption sites, binding mechanism and charge transfer at a coverage of Theta(NO) = 0.25, 0.50, 0.75 monolayer (ML). Based on our study, an unified picture for the interaction between NO and TM(111) and site preference is established, and valuable insights are obtained. At low coverage (0.25 ML), we find that the interaction of NO/TM(111) is determined by an electron donation and back-donation process via the interplay between NO 5sigma/2pi* and TM d-bands. The extent of the donation and back-donation depends critically on the coordination number (adsorption sites) and TM d-band filling, and plays an essential role for NO adsorption on TM surfaces. DFT calculations shows that for TMs with high d-band filling such as Pd and Pt, hollow-site NO is energetically the most favorable, and top-site NO prefers to tilt away from the normal direction. While for TMs with low d-band filling (Rh and Ir), top-site NO perpendicular to the surfaces is energetically most favorable. Electronic structure analysis show that irrespective of the TM and adsorption site, there is a net charge transfer from the substrate to the adsorbate due to overwhelming back-donation from the TM substrate to the adsorbed NO molecules. The adsorption-induced change of the work function with respect to bare surfaces and dipole moment is however site dependent, and the work function increases for hollow-site NO, but decreases for top-site NO, because of differences in the charge redistribution. The interplay between the energetics, lateral interaction and charge transfer, which is element dependent, rationalizes the structural evolution of NO adsorption on TM(111) surfaces in the submonolayer regime.

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Metallicity of Ultrathin Metal Layers

Cited by 12 publications

References 32 publications

Ethanol and Water Adsorption on Close-Packed 3d, 4d, and 5d Transition-Metal Surfaces: A Density Functional Theory Investigation with van der Waals Correction

Ethanol and Water Adsorption on Close-Packed 3d, 4d, and 5d Transition-Metal Surfaces: A Density Functional Theory Investigation with van der Waals Correction

Trends in adsorption of noble gases He, Ne, Ar, Kr, and Xe onPd(111)(3×3)R30°: All-electron

Theory of nitride oxide adsorption on transition metal (111) surfaces: a first-principles investigation

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