The oxidation of CO at MgO supported gold aggregates is studied by means density functional theory calculations. In addition to serving as a structural promoter holding the particles, supporting oxide also takes an active role in bonding and activation adsorbates bound gold. stabilizes peroxolike reaction intermediate, CO.O2, causes steric repulsion CO. most reactive site Au/MgO appears where shelters thereby creating cavity several low-coordinated Au atoms Mg2+ cations from substrate can...

Density functional theory calculations are performed for the adsorption of O2, coadsorption CO, and CO+O2 reaction at interfacial perimeter nanoparticles supported by rutile TiO2(110). Both stoichiometric reduced TiO2 surfaces considered, with various relative arrangements Au particles respect to substrate vacancies. Rather stable binding configurations found O2 adsorbed either trough Ti atoms or leaning against particles. The presence a particle strongly stabilizes O2. A sizable electronic...

String quartets: Guanine molecules self-assemble into a hydrogen-bonded network of G quartets upon deposition under ultrahigh vacuum conditions onto Au(111) surfaces as shown by STM (see picture). The resilience the H-bonded (stable up to 400 K) is explained through cooperative increase in strength H-bonds between guanine quartet.

Epoxidation made easy: Subnanometer gold clusters immobilized on amorphous alumina result in a highly active and selective catalyst for propene epoxidation. The highest selectivity is found gas mixtures involving oxygen water, thus avoiding the use of hydrogen. Ab initio DFT calculations are used to identify key reaction intermediates pathways. results confirm high activity owing formation oxide metallacycles. Al green, Au yellow, O red, C gray.

We present a density-functional-theory (DFT) study of the reactivity towards CO oxidation Au nanoparticles supported by MgO(100). model two geometrical aspects particles, low index facets and Au-MgO interface boundary. The precise structure boundary depends on size different models with either small or large contact angles are introduced. For all systems, we find that reaction proceeds via adsorption, trapping ${\mathrm{O}}_{2},$ leading to formation metastable...

The properties of reduced rutile TiO2(110) surfaces, as well the adsorption, diffusion, and dissociation molecular oxygen are investigated by means density functional theory. O2 molecule is found to bind strongly bridging vacancies, attaining a state with an expanded O-O bond 1.44 A. also binds (with somewhat shortened lengths) fivefold coordinated Ti atoms in troughs between rows, but only when vacancies present somewhere surface. In all cases, magnetic moment lost upon adsorption. lengths...

Density functional theory has been used to study the adsorption of molecular H2 on a graphene layer. Different sites top atoms, bonds and center carbon hexagons have considered compared. We conclude that most stable configuration is physisorbed above hexagon. Barriers for classical diffusion are, however, very small.

Density functional theory has been used to study the interaction of molecular and atomic hydrogen with (5,5) (6,6) single-wall carbon nanotubes. Static calculations allowing for different degrees structural relaxation are performed, in addition dynamical simulations. Molecular physisorption inside outside nanotube walls is predicted be most stable state those systems. The binding energies H2 molecule range 0.04–0.07 eV. This means that uptake release from nanotubes a relatively easy process,...

The interaction potential of a $\mathrm{Li}$ atom with graphene layer is calculated using the local density approximation to functional theory. Two configurations corresponding different separations between in neighboring supercells were considered determine effect $\mathrm{Li}\text{\ensuremath{-}}\mathrm{Li}$ on binding graphene. equilibrium position not affected by and remains same both cases. It equal $3.1\phantom{\rule{0.3em}{0ex}}\mathrm{a.u.}$ above at center hexagonal ring formed...

Using scanning tunneling microscopy we have studied the nucleation and growth of unidirectional molecular rows upon adsorption amino acid cysteine onto anisotropic Au(110)-(1 x 2) surface under ultrahigh vacuum conditions. By modeling a large variety possible geometries using density-functional theory calculations, find that in optimum, lowest energy configuration, no significant intermolecular interactions exist along direction. Instead driving force for formation is an adsorbate-induced...

Abstract A major drawback of state‐of‐the‐art proton exchange membrane fuel cells is the CO poisoning platinum catalysts. It known that reduced if alloys are used, but underlying mechanism therefore still under debate. We study influence dopant atoms on adsorption small clusters using mass spectrometry experiments and density functional calculations. significant reduction in reactivity for Nb‐ Mo‐doped attributed to electron transfer from those highly coordinated dopants Pt concomitant lower...

The structure, stability, and O2 adsorption properties of anionic Au(n) (n=1-11) clusters either free or supported at defected MgO100 surfaces are investigated using density-functional theory. is strong whenever unpaired electrons present, except for some small, supported, planar, high-band-gap clusters. These have the pinned by Madelung potential support. Larger (starting Au7-Au8) become three dimensional metallic. This ensures that while one cluster orbital to defect, another comparable...

The chemical properties of small gold clusters Aun with n up to 10 atoms were investigated using density functional theory (DFT). These have planar structures, and we analyzed the effects planarity on chemistry clusters. Using atomic hydrogen as a probe, found strong site dependence reactivity: H preferentially react at regions rim cluster. A directionality bonds formed was also observed. Bonds in directions contained plane Au cluster are preferred, along direction perpendicular generally...

Gemeinsam sind wir stark: Guaninmoleküle bilden bei der Abscheidung im Ultrahochvakuum auf Au(111)-Oberflächen spontan ein H-Brücken-gebundenes Netzwerk aus G-Quartetten, wie STM-Aufnahmen belegen (siehe Bild). Die Unverwüstlichkeit des Netzwerks (bis 400 K stabil) wird mit einer kooperativen Zunahme Stärke H-Brücken zwischen Guaninmolekülen in einem Quartett erklärt.

Abstract Epoxidieren leicht gemacht : Subnanometergroße Goldcluster auf amorphem Aluminiumoxid sind ein hoch aktiver und selektiver Katalysator für die Epoxidierung von Propen. Am höchsten ist Selektivität bei Gasmischungen, Sauerstoff Wasser enthalten, sodass der Einsatz Wasserstoff vermieden werden kann. Ab‐initio‐Dichtefunktionalrechnungen lieferten Informationen über Schlüsselintermediate Reaktionswege. Demnach beruht Aktivität des Katalysators Bildung Propenoxid‐Metallacyclen. Al grün,...

Abstract A major drawback of state‐of‐the‐art proton exchange membrane fuel cells is the CO poisoning platinum catalysts. It known that reduced if alloys are used, but underlying mechanism therefore still under debate. We study influence dopant atoms on adsorption small clusters using mass spectrometry experiments and density functional calculations. significant reduction in reactivity for Nb‐ Mo‐doped attributed to electron transfer from those highly coordinated dopants Pt concomitant lower...

Extensive Molecular Dynamics simulations have been performed to investigate the structural and thermal properties of Si-doped fullerenes containing one two silicon atoms. Both, a many-body potential ab initio Density Functional Theory (DFT) used features heterofullerenes. The competition between exohedral substitutional types doping, as function fullerene size (both even odd heterofullerenes considered) Si concentration, is analyzed. DFT calculations confirm main trends obtained with...

Density functional calculations are performed to study the interaction of molecular and atomic hydrogen with (5,5) (6,6) single-wall carbon nanotubes. Molecular physisorption is predicted be most stable adsorption state, molecule at equilibrium a distance 5-6 a.u. from nanotube wall. The energies outside nanotubes approximately 0.07 eV, larger inside, reaching value 0.17 eV inside nanotube. Although these binding appear lower than values required for an efficient adsorption/desorption...