Comparative dynamical study of the HD and isotopomers interacting with Pd(111) and Cu(110) surfaces

Ramírez, Claudio; Busnengo, H. F.

doi:10.1016/j.susc.2009.07.017

Cited by 4 publications

(5 citation statements)

References 38 publications

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“…The authors found that, for the incidence energies shown in Fig. 132 The average rotational energy of backscattered HD was in good agreement with experiments 62 for Pd(111), but not for Cu (110). 170 Ramírez and Busnengo performed QCT, C-ZPE, and CT calculations on the reactive and rotationally inelastic scattering of HD from Pd (111) and Cu (110).…”

Section: F Dissociation Of H 2 On Low Index Metal Surfacessupporting

confidence: 53%

“…Qualitative agreement was also found for the dependence of the reaction probability on the incidence angle, which differed for the two W faces. 132 They found no difference between the reaction of HD and H 2 on Pd(111), but they did find a somewhat higher reaction probability of H 2 on Cu(110) than of HD, which could be attributed to the higher zero-point energy of H 2 . 38, both direct trapping and direct mechanisms contribute to the reaction, with dynamic trapping making a bigger contribution for W(100).…”

Section: F Dissociation Of H 2 On Low Index Metal Surfacesmentioning

confidence: 89%

“…244 AIMD 146 and KMC 209 calculations have started addressing the dynamics and kinetics of H 2 dissociation over reactive atoms such as Pd embedded in less reactive metals like Cu, and the subsequent spillover to the less reactive metal, inspired by new experiments. H 2 + low index transition metal surface systems that have been studied using PESs based on standard GGA DFs include H 2 + Pt(111), 179 H 2 + W(100) and W(110), 170 HD + Pd(111), 132 HD + Cu(110), 132 H 2 and D 2 + Cu(110), 181,186 H 2 + Rh(111), 171 and H 2 and D 2 + Ag (111). 70,322 The activated H 2 + NiAl(110) system might constitute a useful benchmark system of activated dissociation on an alloy surface, 245 with molecular beam sticking experiments 319 and diffraction experiments 55,58 available.…”

Section: Discussionmentioning

confidence: 99%

“…In the simplest one, often simply called the classical trajectory (CT) method, no zero-point vibrational energy is imparted to the molecule initially. [128][129][130][131][132][133] 2E. Earlier reviews 29,30 have shown that the QCT method yields better results when compared to quantum dynamical (QD) calculations than the CT method for activated dissociation, but that the CT method may outperform the QCT method in some cases for non-activated dissociation.…”

Section: D Classical Trajectory Methodsmentioning

confidence: 99%

“…38, both direct trapping and direct mechanisms contribute to the reaction, with dynamic trapping making a bigger contribution for W(100). 132 The reactive and non-reactive scattering of H 2 from Cu(110) was studied by Salin and co-workers 181,186 on the basis of a PW91 PES. 132 They found no difference between the reaction of HD and H 2 on Pd(111), but they did find a somewhat higher reaction probability of H 2 on Cu(110) than of HD, which could be attributed to the higher zero-point energy of H 2 .…”

Section: F Dissociation Of H 2 On Low Index Metal Surfacesmentioning

confidence: 99%

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Quantum and classical dynamics of reactive scattering of H₂ from metal surfaces

2016

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We review the state-of-the art in dynamics calculations on the reactive scattering of H2 from metal surfaces, which is an important model system of an elementary reaction that is relevant to heterogeneous catalysis. In many applications, quantum dynamics and classical trajectory calculations are performed within the Born-Oppenheimer static surface model. However, ab initio molecular dynamics (AIMD) is finding increased use in applications aimed at modeling the effect of surface phonons on the dynamics. Molecular dynamics with electronic friction has been used to model the effect of electron-hole pair excitation. Most applications are still based on potential energy surfaces (PESs) or forces computed with density functional theory (DFT), using a density functional within the generalized gradient approximation to the exchange-correlation energy. A new development is the use of a semi-empirical version of DFT (the specific reaction parameter (SRP) approach to DFT). We also discuss the accurate methods that have become available to represent electronic structure data for the molecule-surface interaction in global PESs. It has now become possible to describe highly activated H2 + metal surface reactions with chemical accuracy using the SRP-DFT approach, as has been shown for H2 + Cu(111) and Cu(100). However, chemical accuracy with SRP-DFT has yet to be demonstrated for weakly activated systems like H2 + Ru(0001) and non-activated systems like H2 + Pd(111), for which SRP DFs are not yet available. There is now considerable evidence that electron-hole pair (ehp) excitation does not need to be modeled to achieve the (chemically) accurate calculation of dissociative chemisorption and scattering probabilities. Dynamics calculations show that phonons can be safely neglected in the chemically accurate calculation of sticking probabilities on cold metal surfaces for activated systems, and in the calculation of a number of other observables. However, there is now sufficient evidence to suggest that the decision on whether or not to neglect phonons should be taken with care, with appropriate consideration of the observable to be computed and of the relevant surface temperature. AIMD calculations have provided valuable insights into the mechanisms that are operative in the dissociative adsorption and absorption of hydrogen on/in precovered metal surfaces. Classical and quantum dynamics calculations have shown that the reaction probability of H2 on Pt surfaces consisting of (100) steps and (111) terraces can to a very good approximation be computed as a weighted average of the reactivities on the steps and terraces. Progress obtained with dynamics calculations on the scattering of H2 from alloys and from simple low index metal surfaces is also reported. Insights that may be obtained on the reactivity of a metal surface from the prominent presence of out-of-plane diffraction or, conversely, the complete absence of diffraction, are discussed. A new field has been opened up by experiments on H2 scattering from surfaces at fast graz...

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Section: F Dissociation Of H 2 On Low Index Metal Surfacessupporting

confidence: 53%

Section: F Dissociation Of H 2 On Low Index Metal Surfacesmentioning

confidence: 89%

Section: Discussionmentioning

confidence: 99%

Section: D Classical Trajectory Methodsmentioning

confidence: 99%

Section: F Dissociation Of H 2 On Low Index Metal Surfacesmentioning

confidence: 99%

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Quantum and classical dynamics of reactive scattering of H₂ from metal surfaces

2016

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Kinetic Evidence for a Non‐Langmuir‐Hinshelwood Surface Reaction: H/D Exchange over Pd Nanoparticles and Pd(111)

2013

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The mechanism of hydrogen recombination on a Pd(111) single crystal and well-defined Pd nanoparticles is studied using pulsed multi-molecular beam techniques and the H2/D2 isotope exchange reaction. The focus of this study is to obtain a microscopic understanding of the role of subsurface hydrogen in enhancing the associative desorption of molecular hydrogen. HD production from H2 and D2 over Pd is investigated using pulsed molecular beams, and the temperature dependence and reaction orders are obtained for the rate of HD production under various reaction conditions designed to modulate the amount of subsurface hydrogen present. The experimental data are compared to the results of kinetic modeling based on different mechanisms for hydrogen recombination. We found that under conditions where virtually no subsurface hydrogen species are present, the HD formation rate can be described exceptionally well by a classic Langmuir-Hinshelwood model. However, this model completely fails to reproduce the experimentally observed high HD formation rates and the reaction orders under reaction conditions where subsurface hydrogen is present. To analyze this phenomenon, we develop two kinetic models that account for the role of subsurface hydrogen. First, we investigate the possibility of a change in the reaction mechanism, where recombination of one subsurface and one surface hydrogen species (known as a breakthrough mechanism) becomes dominant when subsurface hydrogen is present. Second, we investigate the possibility of the modified Langmuir-Hinshelwood mechanism with subsurface hydrogen lowering the activation energy for recombination of two hydrogen species adsorbed on the surface. We show that the experimental reaction kinetics can be well described by both kinetic models based on non-Langmuir-Hinshelwood-type mechanisms.

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