Ultrathin metal films and particles on oxide surfaces: structural, electronic and chemisorptive properties

Campbell, Charles T.

doi:10.1016/s0167-5729(96)00011-8

Cited by 1,531 publications

(731 citation statements)

References 255 publications

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“…It has a different structure when it carries out oxidation reactions than when it rearranges organic molecules. This chameleon-like behavior makes it very versatile in many catalytic reactions [19][20][21] . Three aspects of the study of molecular surface chemistry of the metal are highlighted here; the study of platinum single crystal surfaces in a vacuum, the catalytic activity of platinum single crystal surfaces in high pressures and the synthesis, characterization and catalytic reactions on platinum nanoparticles 1-10 nm in size.…”

Section: Introductionmentioning

confidence: 99%

Molecular surface chemistry by metal single crystals and nanoparticles from vacuum to high pressure

2008

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Model systems for studying molecular surface chemistry have evolved from single crystal surfaces at low pressure to colloidal nanoparticles at high pressure. Low pressure surface structure studies of platinum single crystals using molecular beam surface scattering and low energy electron diffraction techniques probe the unique activity of defects, steps and kinks at the surface for dissociation reactions (H-H, C-H, C-C, O=O bonds). High-pressure investigations of platinum single crystals using sum frequency generation vibrational spectroscopy have revealed the presence and the nature of reaction intermediates. High pressure scanning tunneling microscopy of platinum single crystal surfaces showed adsorbate mobility during a catalytic reaction. Nanoparticle systems are used to determine the role of metal-oxide interfaces, site blocking and the role of surface structures in reactive surface chemistry. The size, shape and composition of nanoparticles play important roles in determining reaction activity and selectivity.

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Section: Introductionmentioning

confidence: 99%

Molecular surface chemistry by metal single crystals and nanoparticles from vacuum to high pressure

2008

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“…From the energetic point of view, a precondition for 3D growth (i.e., nonwetting), is that the adhesion energy of the Pd metal on the oxide is smaller than twice the surface free energy of the vacuum-metal interface of the liquid metal [19]. In the case of late transition metals on oxides, this criterion is usually met, and thus 3D growth is observed in most cases [14].…”

Section: The Hexagonal W'-tio X (Wagon-wheel-like) Phasementioning

confidence: 99%

Distribution of Pd clusters on ultrathin, epitaxial TiOx films on Pt3Ti(111)

Breinlich¹,

Buchholz²,

Moors³

et al. 2016

Nano Online

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Scanning tunnelling microscopy (STM) was used to investigate the nucleation and growth of palladium clusters on two different, ultrathin, epitaxial, titania films grown on a Pt 3 Ti(111) surface. The first oxide phase, z'-TiO x , is anisotropic and consists of parallel stripes separated by trenches. Defects (i.e., oxygen vacancies) in this structure are confined to these trenches and act as nucleation sites. Therefore, the Pd clusters are mostly arranged in unidirectional rows along the trenches, creating a template effect. The second phase, w'-TiO x , exhibits a hexagonal, long range, (7 × 7)R21.8°, Moiré-type superstructure with fewer and shallower defects, making the template effect less discernible. 2007

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“…One uses either conductive oxide single crystals or thin films grown on top of metal single crystals. The procedures have been extensively reviewed , Campbell 1997, Diebold 2003, Freund 1997, Freund et al 1996, Freund and Pacchioni 2008, Freund and Goodman 2007, Henry 1998, Risse et al 2008. The supports relevant to the present review are alumina and niobia.…”

Section: Model Studiesmentioning

confidence: 99%

“…Elemental metal particles have been studied extensively on a number of bulk single crystal and thin film oxide supports (Campbell 1997, Henry 1998, Freund 1997, Freund and Pacchioni 2008, Goodman 1995. For the latter case, which is the subject of the current discussion, we refer to a number of reviews.…”

Section: Martin Schmal and Hans-joachim Freundmentioning

confidence: 99%

Towards an atomic level understanding of niobia based catalysts and catalysis by combining the science of catalysis with surface science

Schmal¹,

Freund

2009

An. Acad. Bras. Ciênc.

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The science of catalysis and surface science have developed, independently, key information for understanding catalytic processes. One might argue: is there anything fundamental to be discovered through the interplay between catalysis and surface science?Real catalysts of monometallic and bimetallic Co/Nb 2 O 5 and Pd-Co/Nb 2 O 5 catalysts showed interesting selectivity results on the Fischer-Tropsch synthesis (Noronha et al. 1996, Rosenir et al. 1993. The presence of a noble metal increased the C + 5 selectivity and decreased the methane formation depending of the reduction temperature. Model catalyst of Co-Pd supported on niobia and alumina were prepared and characterized at the atomic level, thus forming the basis for a comparison with "real" support materials. Growth, morphology and structure of both pure metal and alloy particles were studied. It is possible to support the strong metal support interaction suggested by studies on real catalysts via the investigation of model systems for niobia in comparison to alumina support in which this effect does not occur. Formation of Co 2+ penetration into the niobia lattice was suggested on the basis of powder studies and can be fully supported on the basis of model studies. It is shown for both real catalysts and model systems that oxidation state of Co plays a key role in controlling the reactivity in Fischer-Tropsch reactions systems and that the addition of Pd is a determining factor for the stability of the catalyst. It is demonstrated that the interaction with unsaturated hydrocarbons depends strongly on the state of oxidation.

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Ultrathin metal films and particles on oxide surfaces: structural, electronic and chemisorptive properties

Cited by 1,531 publications

References 255 publications

Molecular surface chemistry by metal single crystals and nanoparticles from vacuum to high pressure

Molecular surface chemistry by metal single crystals and nanoparticles from vacuum to high pressure

Distribution of Pd clusters on ultrathin, epitaxial TiOx films on Pt3Ti(111)

Towards an atomic level understanding of niobia based catalysts and catalysis by combining the science of catalysis with surface science

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