Quantum Mechanical Calculations of Chemical Interactions on Transition Metal Surfaces

Ruette, Fernando; Sierraalta, Aníbal; Hernández, Aureliano

doi:10.1007/978-94-017-2825-6_9

Cited by 17 publications

(21 citation statements)

References 420 publications

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“…The atomic orbitals of sulfur and oxygen were expressed in terms of double-ζ quality basis sets augmented with polarization functions. ,, Sn and Pt were described using the effective-core potentials and basis sets employed in our previous study for the adsorption of H 2 S and S 2 on ( × )R30°-Sn/Pt(111) . For these elements, we treated explicitly only the valence shells: 5s and 5p orbitals of Sn, , plus 5d and 6s,p orbitals of Pt. , Previous experience indicates that these basis sets provide satisfactory results for the adsorption geometries of sulfur-containing molecules. , On the other hand, the energetics derived from these SCF calculations for adsorption reactions are not quantitative and simply provide a guide for the interpretation of experimental results. ,, The size of the basis sets, the use of finite clusters, and the lack of electron correlation introduce uncertainty in the computed bonding energies. , Despite this limitation, the use of ab initio SCF methods with cluster models has proved to be a very useful approach for studying a large variety of surface phenomena. , …”

Section: Experimental and Theoretical Methodsmentioning

confidence: 99%

Surface Chemistry of SO₂on Sn and Sn/Pt(111) Alloys: Effects of Metal−Metal Bonding on Reactivity toward Sulfur

et al. 1998

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The surface chemistry of SO2 on polycrystalline Sn, Pt(111), and a ( x )R30°-Sn/Pt(111) surface alloy has been investigated using synchrotron-based high-resolution photoemission and ab initio self-consistent field calculations. Metallic tin has a large chemical affinity for SO2. At 100−150 K, SO2 disproportionates on polycrystalline tin forming multilayers of SO3 (2SO2,a → SOgas + SO3,a). At these low temperatures, the full dissociation of SO2 (SO2,a → Sa + 2Oa) is minimal. As the temperature is raised to 300 K, the SO3 decomposes, yielding SO4, S, and O on the surface. Pure tin exhibits a much higher reactivity toward SO2 than late transition metals (Ni, Pd, Pt, Cu, Ag, Au). In contrast, tin atoms in contact with Pt(111) interact weakly with SO2. A ( × )R30°-Sn/Pt(111) alloy is much less reactive toward SO2 than polycrystalline tin or clean Pt(111). At 100 K, SO2 adsorbs molecularly on ( × )R30°-Sn/Pt(111). Most of the adsorbed SO2 desorbs intact from the surface (250−300 K), whereas a small fraction dissociates into S and O. The drastic drop in reactivity when going from pure tin to the ( × )R30°-Sn/Pt(111) alloy can be attributed to a combination of ensemble and electronic effects. On the other hand, the low reactivity of the Pt sites in ( × )R30°-Sn/Pt(111) with respect to Pt(111) is a consequence of electronic effects. The Pt−Sn bond is complex, involving a Sn(5s,5p) → Pt(6s,6p) charge transfer and a Pt(5d) → Pt(6s,6p) rehybridization that localize electrons in the region between the metal centers. These phenomena reduce the electron donor ability of Pt and Sn, and both metals are not able to respond in an effective way to the presence of SO2. The Sn/Pt system illustrates how a redistribution of electrons that occurs in bimetallic bonding can be useful for the design of catalysts that have a remarkably low reactivity toward SO2 and for controlling sulfur poisoning.

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Section: Experimental and Theoretical Methodsmentioning

confidence: 99%

Surface Chemistry of SO₂on Sn and Sn/Pt(111) Alloys: Effects of Metal−Metal Bonding on Reactivity toward Sulfur

et al. 1998

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“…Type I1 chemisorption is irreversible and Type I1 is deduced to consist of bridged Zn-H. Many theoretical studies have been undertaken to increase our comprehension of the catalytic behavior of the H20 and H2 adsorption process by semiempirical methods and ab initio cluster models [4,25,26] as well. The H20 and H2 molecular interaction as well as the heterolytic dissociation with the ZnO surface was investigated by extended Huckel procedures [27,28], ab initio clusters with Madelung potential for point charge [29], and semiempirical molecular orbital methods [30,31].…”

Section: Introductionmentioning

confidence: 99%

H2O and H2 interaction with ZnO surfaces: A MNDO, AM1, and PM3 theoretical study with large cluster models

Martins

Andrés

Longo

et al. 1996

Int. J. Quantum Chem.

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mWe investigated the adsorption and heterolytic dissociation of H 2 0 and H2 molecules on a (ZnO)*? cluster corresponding to ZnO (OOOl), (OOOl), and (lOi0) surfaces using MNDO, AM^, and PM3 semiempirical procedures. The geometry of the adsorbed molecule has been optimized in order to analyze binding energies, charge transfer, and preferential sites of interaction. The adsorbed species interact most strongly when it is bonded to the twofold coordinated zinc atom of the cluster surface. The interaction of the H 2 0 molecule with the surface of ZnO has a charge transfer from H 2 0 to the surface ranging between 0.17 and 0.27 au. The neighboring atoms of the surface are the main receptors during the process of charge transfer. Our results indicate that there is a weak bonding of the hydrogen atom from OH with the oxygen surface atom that could produce the O--H....O band. The interaction of the H2 molecule with the surface is generally weak and only the PM3 method yields a strong binding energy for this interaction. There is a charge transfer from the H2 molecule to the surface. The chemisorption of H on oxygen atom of the surface transfer charge from the surface to the H. We also calculated the vibrational analyses for these interactions on ZnO surface and compared our results with available experimental data.

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“…Semiempirical methods have become increasingly popular for the study of complex molecular systems because of their ability to handle a large number of electrons . Standard choice of parameters for the Hamiltonian prevents, in a way, the kind of systematic improvement that can be achieved with a multiconfigurational or perturbational procedure.…”

Section: Introductionmentioning

confidence: 99%

A Semiempirical Quantum Chemical Study of Some Local Aspects of Ionic Conduction in Poly(ethylene oxide): Ion Motion and Rotational Barriers

1998

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Several aspects of electronic potential energy curves for the ionic conduction process in poly(ethylene oxide) are modeled. A supermolecule is taken as a local model for a section of a polymer chain in the amorphous phase. Ion-polymer interaction, rotational barriers for the free and charged supermolecule, and the activation energy for intrachain ionic motion were calculated. For the latter, the oxygen-cation distance is considered as the reaction coordinate. The supermolecule assembly consists of five monomer units and a proton as probe ion. Strong coupling occurs between the motion of the ion and the flexional dynamics of the polymer that is manifest in the rearrangement that takes place in the nuclear framework of the chain as the position of the ion changes. The calculated activation energy was found in the range of the experimental values. All these results are consistent with the picture that ionic conduction in solid electrolytes such as poly(ethylene oxide) takes place mainly in the amorphous phase, because a considerable degree of flexibility on the polymer backbone is required to allow for the necessary bond rearrangements to promote cationic motion.

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Quantum Mechanical Calculations of Chemical Interactions on Transition Metal Surfaces

Cited by 17 publications

References 420 publications

Surface Chemistry of SO₂on Sn and Sn/Pt(111) Alloys: Effects of Metal−Metal Bonding on Reactivity toward Sulfur

Surface Chemistry of SO₂on Sn and Sn/Pt(111) Alloys: Effects of Metal−Metal Bonding on Reactivity toward Sulfur

H2O and H2 interaction with ZnO surfaces: A MNDO, AM1, and PM3 theoretical study with large cluster models

A Semiempirical Quantum Chemical Study of Some Local Aspects of Ionic Conduction in Poly(ethylene oxide): Ion Motion and Rotational Barriers

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Quantum Mechanical Calculations of Chemical Interactions on Transition Metal Surfaces

Cited by 17 publications

References 420 publications

Surface Chemistry of SO2on Sn and Sn/Pt(111) Alloys: Effects of Metal−Metal Bonding on Reactivity toward Sulfur

Surface Chemistry of SO2on Sn and Sn/Pt(111) Alloys: Effects of Metal−Metal Bonding on Reactivity toward Sulfur

H2O and H2 interaction with ZnO surfaces: A MNDO, AM1, and PM3 theoretical study with large cluster models

A Semiempirical Quantum Chemical Study of Some Local Aspects of Ionic Conduction in Poly(ethylene oxide): Ion Motion and Rotational Barriers

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Surface Chemistry of SO₂on Sn and Sn/Pt(111) Alloys: Effects of Metal−Metal Bonding on Reactivity toward Sulfur

Surface Chemistry of SO₂on Sn and Sn/Pt(111) Alloys: Effects of Metal−Metal Bonding on Reactivity toward Sulfur