O2 Adsorption Dynamics at Metal Surfaces: Non-adiabatic Effects, Dissociation and Dissipation

Carbogno, Christian; Groß, Axel; Meyer, Jörg

doi:10.1007/978-3-642-32955-5_16

Cited by 23 publications

(23 citation statements)

References 126 publications

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“…The triplet multiplicity of small Pd clusters ground state is relevant considering that the O 2 molecule exhibits little or no reactivity with closed-shell molecules [31]. The Pd clusters have unpaired electrons uniformly distributed among Pd atoms in the triplet and quintet states.…”

Section: Resultsmentioning

confidence: 99%

The CO oxidation mechanism on small Pd clusters. A theoretical study

et al. 2015

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CO is a pollutant that is removed by oxidation using Pd, Pt or Rh as catalysts in the exhaust pipes of vehicles. Here, a quantum chemistry study on the CO + O2 reaction catalyzed by small Pdn clusters (n ≤ 5) using the PBE/TZ2P/ZORA method is performed. The limiting step in this reaction at low temperature and coverage is the O2 dissociation. Pdn clusters catalyze the O=O bond breaking, reducing the energy barrier from 119 kcal mol(-1) without catalyst to ∼35 kcal mol(-1). The charge transfer from Pd to the O2,ad antibonding orbital weakens, and finally breaks the O─O bond. The CO oxidation takes place by the Eley-Rideal (ER) mechanism or the Langmuir-Hinshelwood (LH) mechanism. The ER mechanism presents an energy barrier of 4.10-7.05 kcal mol(-1) and the formed CO2 is released after the reaction. The LH mechanism also shows barrier energies to produce CO2 (7-15 kcal mol(-1)) but it remains adsorbed on Pd clusters. An additional energy (7-25 kcal mol(-1)) is necessary to desorb CO2 and release the metal site. The triplet multiplicity is the ground states of studied Pdn clusters, with the following order of stability: triplet > singlet > quintet state. Graphical Abstract CO oxidation mechanism on small Pd clusters.

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Section: Resultsmentioning

confidence: 99%

The CO oxidation mechanism on small Pd clusters. A theoretical study

et al. 2015

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“…39,40 This is not too surprising considering that a major break-down of the electronic adiabaticity of the adsorption process had been invoked as one possible reason behind the O 2 /Al(111) discrepancy. 39,41 This unlikely applies to Pd(100), which exhibits a very high electronic density-of-states at the Fermi level and for which only small energy losses to electronhole pairs during O 2 adsorption have been calculated. 28 In terms of overall (rough) magnitude, the favorable agreement of experimental and theoretical sticking extends over the entire range of incidence energies shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…From a bulk of work on O 2 adsorption on late transition metals, 41 the PBE and RPBE functionals can be seen as popular representatives for opposite ends within the range of current gradient-corrected functionals, with the prior likely more on the overbinding side and the latter possibly slightly underbinding. Within the understanding of the just presented dynamical analysis, concomitant uncertainties in the energetic description of the molecular chemisorption well (E b and E diss ) at the semi-local DFT level are nevertheless unlikely to cause the wrong trend of the sticking curve with E i as compared to the experimental data.…”

Section: Resultsmentioning

confidence: 99%

Fingerprints of energy dissipation for exothermic surface chemical reactions: O2 on Pd(100)

Bukas

Mitra

Meyer

et al. 2015

The Journal of Chemical Physics

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We present first-principles calculations of the sticking coefficient of O 2 at Pd(100) to assess the effect of phononic energy dissipation on this kinetic parameter. For this we augment dynamical simulations on sixdimensional potential energy surfaces (PESs) representing the molecular degrees of freedom with various effective accounts of surface mobility. In comparison to the prevalent frozen-surface approach energy dissipation is found to qualitatively affect the calculated sticking curves. At the level of a generalized Langevin oscillator (GLO) model we achieve good agreement with experimental data. The agreement is similarly reached for PESs based on two different semi-local density-functional theory functionals. This robustness of the simulated sticking curve does not extend to the underlying adsorption mechanism, which is predominantly directly dissociative for one functional or molecularly trapped for the other. Completely different adsorption mechanisms therewith lead to rather similar sticking curves that agree equally well with the experimental data. This highlights the danger of the prevalent practice to extract corresponding mechanistic details from simple fingerprints of measured sticking data for such exothermic surface reactions.

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“…Carbogno and co-workers describe the issue and recent attempts to resolve it for O 2 adsorption on simple metal surfaces in Ref. 27. For basic adsorption on an ideal surface, recent work has employed surface-hopping algorithms in which adiabatic triplet and singlet potential energy surfaces (PES) are simultaneously calculated.…”

Section: Computational Methodologymentioning

confidence: 99%

Oxidation of ligand-protected aluminum clusters: An ab initio molecular dynamics study

Alnemrat

Hooper

2014

The Journal of Chemical Physics

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Oxidation of ligand-protected aluminum clusters: an ab-initio molecular dynamics study. "J. Chem. Phys. 140, 104313 (2014 We report Car-Parrinello molecular dynamics simulations of the oxidation of ligand-protected aluminum clusters that form a prototypical cluster-assembled material. These clusters contain a small aluminum core surrounded by a monolayer of organic ligand. The aromatic cyclopentadienyl ligands form a strong bond with surface Al atoms, giving rise to an organometallic cluster that crystallizes into a low-symmetry solid and is briefly stable in air before oxidizing. Our calculations of isolated aluminum/cyclopentadienyl clusters reacting with oxygen show minimal reaction between the ligand and O 2 molecules at simulation temperatures of 500 and 1000 K. In all cases, the reaction pathway involves O 2 diffusing through the ligand barrier, splitting into atomic oxygen upon contact with the aluminum, and forming an oxide cluster with aluminum/ligand bonds still largely intact. Loss of individual aluminum-ligand units, as expected from unimolecular decomposition calculations, is not observed except following significant oxidation. These calculations highlight the role of the ligand in providing a steric barrier against oxidizers and in maintaining the large aluminum surface area of the solid-state cluster material. [http://dx

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O2 Adsorption Dynamics at Metal Surfaces: Non-adiabatic Effects, Dissociation and Dissipation

Cited by 23 publications

References 126 publications

The CO oxidation mechanism on small Pd clusters. A theoretical study

The CO oxidation mechanism on small Pd clusters. A theoretical study

Fingerprints of energy dissipation for exothermic surface chemical reactions: O2 on Pd(100)

Oxidation of ligand-protected aluminum clusters: An ab initio molecular dynamics study

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