Chemical and electronic properties of ultrathin metal films: The Pd/Re(0001) and Pd/Ru(0001) systems

Ra, Campbell; Ja, Rodriguez; Dw, Goodman

doi:10.1103/physrevb.46.7077

Cited by 122 publications

(83 citation statements)

References 72 publications

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“…The onset of desorption is shifted by another 50 K to higher temperatures, reflecting a further increase in CO adsorption energy. The shift in desorption temperature on the mono-and bilayer Pt covered Ru(0001) surface as compared to desorption from bulk Pt(111) resembles that observed for Pd/Ru(0001), but is even more pronounced [41]. Along with these modifications in the adsorption properties of the Pd surface layer the authors also reported a significant shift in the Pd(3d) core level energies as compared to bulk Pd, indicative of changes in the electronic structure of the Pd layer.…”

Section: Surface Chemistry On Homogeneous Bimetallic Surfacesmentioning

confidence: 72%

Spatially Resolved Chemistry on Bimetallic Surfaces

Behm

1998

Acta Phys. Pol. A

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The local chemical properties of bimetallic surfaces, which are often drastically different from those of each of the components, will be discussed. Using CO adsorption as a probe molecule it will be shown for two model systems, Au/Pd(111) and Pt/Ru(0001), that their chemical properties depend decisively on the local surface structure and that the correct interpretation of area integrating spectroscopic and kinetic data obtained from such surfaces requires detailed knowledge of their (defect) structure and of the distribution of the different components in the surface layer. It will further be shown that information on the local chemical properties of specific structural elements such as monolayer islands and monolayer island edges, and specific surface ensembles can be gained by applying high resolution scanning tunneling microscopy imaging and area integrating spectroscopic techniques in combination to bimetallic surfaces whose morphology and composition is varied in a systematic and controlled way. Based on experimental results adsorption on a monolayer Α / substrate B system is suggested as a model for gaining information on the modifications in chemical properties of ΑB alloy surfaces due to metal-metal interactions.

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Section: Surface Chemistry On Homogeneous Bimetallic Surfacesmentioning

confidence: 72%

Spatially Resolved Chemistry on Bimetallic Surfaces

Behm

1998

Acta Phys. Pol. A

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“…The last decade has witnessed a tremendous growth in our understanding of the chemical and electronic properties of thin metal films supported on foreign metal substrates [1][2][3][4][5][6][7][8][9]. Only shortly after the successful UHV studies, the adsorption and catalytic properties of pseudomorphic Pd films supported on single crystal metal surfaces has also received considerable attention in the field of surface electrochemistry [10][11][12][13][14][15][16][17][18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

CO adsorption and kinetics on well-characterized Pd films on Pt() in alkaline solutions

et al. 2002

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The electrochemistry of CO on a bare Pt(111) electrode as well as a Pt (111) electrode modified with pseudomorphic thin palladium films has been studied in alkaline solution by means of Fourier transform infrared (FTIR) spectroscopy. First Pd films were prepared and well characterized in UHV and subsequently transferred into the electrochemical cell for the registration of the voltammetric profiles. The charge corresponding to the formation of underpotentially deposited hydrogen (H upd ) on these Pt(111)-xPd surfaces was established in sulfuric acid solution as a function of x (0 ≤ x ≤ 1 Pd monolayer (ML)).All subsequent measurements were then performed on electrochemically deposited palladium films using the above H upd -charge vs. Pd coverage relationship to evaluate the amount of electrochemically deposited palladium. FTIR spectra for CO adsorbed on one monolayer and a submonolayer coverage are compared to those of the unmodified Pt(111) surface, all surfaces having identical 2D lattice structures. Infrared absorption bands of CO bound on either Pt(111) or Pt(111)-1ML Pd are clearly 1 distinguished. Spectra of CO adsorbed on Pd submonolayers show characteristic features of both CO bound to Pt and to Pd, indicating that on Pt(111)-xPd surfaces there is no coupling between Pt-CO ad and Pd-CO ad molecules. The kinetics of CO oxidation on these surfaces is determined either by rotating disk electrode (RDE) measurements or by FTIR spectroscopy, monitoring the CO 3 2-production. The oxidation of CO ad on Pt (111) and on Pd modified platinum surfaces starts at the same potential, ca. at 0.2 V. The oxidation rate is, however, considerably lower on the Pt(111)-xPd surfaces than on the Pt(111) surface. The kinetics of CO oxidation appears to be determined by the nature of adsorbed hydroxyl anions (OH ad ), which are more strongly (less active) adsorbed on the highly oxophilic Pd atoms.

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“…Goodman and coworkers, for instance, showed how changes in the chemisorption energy of CO on pseudomorphic overlayers, correlate with measured XPS shifts in the core-level binding energies for the surface metal. 6,7,14,15 Using frontier orbital theory 16,17 and the Newns-Anderson chemisorption model, 18 Hammer and Nørskov developed a simplified chemisorption and reactivity model, 3,[19][20][21] which demonstrated that the metal-adsorbate bond strength is closely related to the surface metal d-band structure. The core-level shifts measured by Goodman and co-workers were shown to be commensurate with changes in the valence d-band center.…”

Section: Introductionmentioning

confidence: 99%

First principles analysis of hydrogen chemisorption on Pd–Re alloyed overlayers and alloyed surfaces

Pallassana

Neurock

Hansen

et al. 2000

The Journal of Chemical Physics

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Gradient corrected periodic density functional theory ͑DFT-GGA͒ slab calculations were used to examine the chemisorption of atomic hydrogen on various Pd-Re alloyed overlayers and uniformly alloyed surfaces. Adsorption was examined at 33% surface coverage, where atomic hydrogen preferred the three-fold fcc sites. The binding energy of atomic hydrogen is observed to vary by as much as 0.7 eV due to Pd-Re interactions. The computed adsorption energies were found to be between Ϫ2.35 eV ͓for monolayer Pd-on-Re, i.e., Pd ML /Re͑0001͔͒ and Ϫ3.05 eV ͓for Pd 33 Re 66 /Pd͑111͔͒. A d-band weighting scheme was developed to extend the Hammer-Nørskov surface reactivity model ͓Surf. Sci. 343, 211 ͑1995͔͒ to the analysis of bimetallic Pd-Re alloyed systems. The hydrogen chemisorption energies are correlated linearly to the surface d-band center, which is weighted appropriately by the d-band coupling matrix elements for Pd and Re. The farther the weighted d-band center is shifted below the Fermi energy, the weaker is the interaction of atomic hydrogen with the alloyed Pd-Re surface.

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Chemical and electronic properties of ultrathin metal films: The Pd/Re(0001) and Pd/Ru(0001) systems

Cited by 122 publications

References 72 publications

Spatially Resolved Chemistry on Bimetallic Surfaces

Spatially Resolved Chemistry on Bimetallic Surfaces

CO adsorption and kinetics on well-characterized Pd films on Pt() in alkaline solutions

First principles analysis of hydrogen chemisorption on Pd–Re alloyed overlayers and alloyed surfaces

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