Chemisorption and Transformation of CHx Fragments (x = 0−3) on a Pd(111) Surface:  A Periodic Density Functional Study

Paul, Jean-François; Sautet, Philippe

doi:10.1021/jp9733227

Cited by 90 publications

(73 citation statements)

References 32 publications

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“…As expected, CH 2 preferentially adsorbs in the bridged position where it can complete the carbon's tetrahedral geometry ( Figure 2E,F). The Pt-C bond length of ∼2.00 Å is in agreement with the work of Kua and Goddard, 26,27 but it is much smaller than the 2.3 Å reported by Paul 46 for the adsorption of CH 2 in the bridged position on Pd-(111). In the case of the Pt 4 /F 2 O cluster, the adsorption of CH 2 leads to a large elongation of the Pt-Pt bond length to 3.07 Å between the Pt atoms forming the bridge.…”

Section: Discussionsupporting

confidence: 90%

Theoretical Study on Pt Particle Adsorbate Bonding: Influence of Support Ionicity and Implications for Catalysis

et al. 2004

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The influence of the support ionicity on the adsorption of H, CH x (x ) 2, 3), and O on supported Pt particles is investigated using density functional theory (DFT). The DFT calculations reveal that the importance of the 6s,p states for the Pt adsorbate bonding increases in the order Pt-O < Pt-CH 2 < Pt-CH 3 < Pt-H. Both the Pt-H and Pt-O bond strengths are strongly affected by changes in the support ionicity whereas the difference for the Pt-CH x bond strength is much smaller. The Pt-H bond strength is higher for ionic supports, whereas the Pt-O bond strength is higher for acidic or more covalent supports. These bond strength changes occur because the support ionicity has a large impact on both the Pt 6s,p and 5d states. On ionic supports with electron rich oxygen atoms, the 6s,p states are pushed toward the surface of a metal cluster where it can participate in H bonding, whereas on supports with electron poor oxygen atoms (existing in acidic supports or for supports with more covalent cations) the 6s,p states are attracted toward the metal-support interface. The Pt 5d states shift to lower binding energy (lower ionization potential) on ionic supports, where it bonds less effectively with the O adsorbate. These findings indicate that the hydrogen and oxygen coverage on Pt particles are strongly determined by the ionicity and acid/base properties of the support and therefore may be the most important for producing changes in the reactivity of Pt wit support ionicity in various hydrogenolysis, hydrogenation, and oxidation reactions.

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Section: Discussionsupporting

confidence: 90%

Theoretical Study on Pt Particle Adsorbate Bonding: Influence of Support Ionicity and Implications for Catalysis

et al. 2004

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“…The calculated adsorption energy is 41.11 kcal/mol (1.78 eV), which is larger than the binding energy of 1.47 eV 33 for the system with a GGA BP86 functional on a two-layer slab for the hollow site, and the possible reason is the difference exchange-correlation function and the calculation model used in the calculation. In ref.…”

Section: Ch 3 /Pd(111)mentioning

confidence: 65%

“…A periodic DFT calculation was performed to study the chemisorption and transformation of CH x fragments on Pd(111). 33 The DFT method with an Amsterdam density functional (ADF) program package was carried out to study methane dissociation and syngas formation on the M(111) surface (M ϭ Rh, Pt, Pd, Cu, Ag, Au) using an M 10 cluster model. 34 The adsorbate binds to the substrates in a distinct approach; thus, the chemisorption energies on the different adsorption sites may be different.…”

mentioning

confidence: 99%

The relationship between adsorption energies of methyl on metals and the metallic electronic properties: A first‐principles DFT study

Wang

et al. 2005

J Comput Chem

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A theoretical study of CH3 adsorbed on the (111) surface of some transition and noble metal surfaces M (M = Cu, Ni, Rh, Pt, Pd, Ag, Au) and on the Fe(100) is presented. We find that the hollow site is preferred more than the top one for Fe, Ni, Rh, and Cu, but it is the other way for Pt, Pd, Au, and Ag. In addition, a good linear relationship was observed between the chemisorption energy and d-band center for Group VIII metals or the square of the coupling matrix element for Group IB metals at the hollow site. Interestingly, with a detailed comparison of the adsorption energies at the top and hollow sites, we find that the adsorption energies among each group are very similar on the top site, which supports the theoretical model of Hammer and Norskov that the coupling between the HOMO of adsorbate and sp states of the metal is dominant and almost equal, and that the second coupling to the d-band contributes less but reflects the change of the adsorption energy. It confirms that the coupling to the d band comprises two opposite factors, that is, the d-band center was attractive and the square of the coupling matrix element was repulsive, such that the contributions from the two factors can counteract each other at the top site.

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“…It is clear from the results that the short-bridge configuration is the most stable one. This has been also shown for another carbene species (CH 2 ), when adsorbed on different metal surfaces [53][54][55][56][57].…”

Section: Stability Of the Interaction Modes Of The Cxymentioning

confidence: 54%

Theoretical Study of the Stability of Carbene Intermediates Formed During the Hydrodechlorination Reaction of the CF x Cl4−x Family on the Pd(110) Surface

2009

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In the present work the stability of the species CCl 2 , CFCl, CF 2 and CHF, which are produced during the hydrodechlorination reaction of the CF x Cl 4-x family, have been investigated on the Pd(110) surface by applying ab initio periodic Density Functional Theory. The most stable configuration for these carbenes on this surface is the short-bridge. Hollow positions have not been found as stationary points in most of the cases. For the chlorinated fragments, the optimisation of these hollow positions resulted in partial or full dechlorinated fragments. The most stable configuration for the carbenes (short-bridge) was compared to the least stable one (top) within different surface conditions in order to verify any change in this stability trend. Both geometries are equally affected by the surface modifications for most of the carbenes. The shortbridge is, however, more sensitive to the coverage increase in the CHF case. CHF has the strongest binding energy to the Pd(110) surface, whilst CF 2 has the least one. The stability trend of CHF, CFCl and CF 2 helped to better understand the selectivity of the hydrodechlorination reaction of the mono carbon CFC's, for example, the suggestion that CF 2 is the most important intermediate on the hydrodechlorination of CF 2 Cl 2 was confirmed by the calculations.

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Chemisorption and Transformation of CH_x Fragments (x = 0−3) on a Pd(111) Surface: A Periodic Density Functional Study

Cited by 90 publications

References 32 publications

Theoretical Study on Pt Particle Adsorbate Bonding: Influence of Support Ionicity and Implications for Catalysis

Theoretical Study on Pt Particle Adsorbate Bonding: Influence of Support Ionicity and Implications for Catalysis

The relationship between adsorption energies of methyl on metals and the metallic electronic properties: A first‐principles DFT study

Theoretical Study of the Stability of Carbene Intermediates Formed During the Hydrodechlorination Reaction of the CF x Cl4−x Family on the Pd(110) Surface

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