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Chusuei, Charles C.; Lai, Xiaofeng; Luo, Kai; Goodman, D. W.

doi:10.1023/a:1009059100646

Cited by 155 publications

(153 citation statements)

References 85 publications

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“…3.15A). 48,250,251,252,253 Using this approach, the spatial distribution and number density of defects has been revealed, however, no information on their nature and electronic properties could be obtained. The first topographic images of undecorated point defects were obtained on the TiO 2 (110) surface, 254,255 although those sites were confused with hydrogen adatoms for a long time due to their similar appearance.…”

Section: Defects In the Oxide Surfacementioning

confidence: 99%

Properties of oxide thin films and their adsorption behavior studied by scanning tunneling microscopy and conductance spectroscopy

Nilius

2009

Surface Science Reports

216

231

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The preparation of thin oxide films on metal supports is a versatile approach to explore the properties of oxide materials that are otherwise inaccessible to most surface science techniques due to their insulating nature. Although substantial progress has been made in the characterization of oxide surfaces with spatially averaging techniques, a local view is often essential to provide comprehensive understanding of such systems. The scanning tunneling microscope (STM) is a powerful tool to obtain atomic-scale information on the growth behavior of oxide films, the resulting surface morphology and defect structure.

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Section: Defects In the Oxide Surfacementioning

confidence: 99%

Properties of oxide thin films and their adsorption behavior studied by scanning tunneling microscopy and conductance spectroscopy

Nilius

2009

Surface Science Reports

216

231

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“…The enhanced catalytic activity of small gold clusters has been ascribed to a number of effects: bilayer structures that exhibit metal-nonmetal transitions [1][2][3], the metal-support interface [4][5][6][7], uncoordinated step-and corner atoms [8][9][10][11], strain [11], charge transfer from the support [12,13], and metal cationic sites [14]. Early work on model Au clusters supported on TiO 2 (110) correlated the presence of Au bilayer cluster morphologies (figure 1) with catalytic activity for CO oxidation [1].…”

mentioning

confidence: 99%

“…(3) With SMSI electron transfer occurs from titania to the supported metal yielding an electron-rich metal D.W. Goodman/Catalytically active Au on Titania [29,30]. For an active Au/TiO 2 model catalyst, core level shifts measured by X-ray photoelectron spectroscopy (XPS) are consistent with electron transfer from titania to Au leading to electron-rich Au [3]. Density functional calculations also are consistent with Au being electron-rich when supported on titania [18,39].…”

mentioning

confidence: 99%

?Catalytically active Au on Titania:? yet another example of a strong metal support interaction (SMSI)?

2005

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In light of the many similarities between previous studies of the so-called strong metal support interaction (SMSI) involving Gr. VIII metals, and catalytically active Au, it is apparent that these two phenomena must be closely related. That active Au on titania spreads to form a bilayer structure, is electron-rich as determined by theory and experiment, nucleates on reduced Ti defects created by annealing to temperatures >750 K, and is deactivated via sintering in oxygen, is convincing evidence that the same basic principles responsible for activation of Au on titania are operative for SMSI involving Gr. VIII metals.KEY WORDS: gold, titania, CO oxidation, strong metal support interaction, SMSI.The enhanced catalytic activity of small gold clusters has been ascribed to a number of effects: bilayer structures that exhibit metal-nonmetal transitions [1][2][3], the metal-support interface [4][5][6][7], uncoordinated step-and corner atoms [8][9][10][11], strain [11], charge transfer from the support [12,13], and metal cationic sites [14]. Early work on model Au clusters supported on TiO 2 (110) correlated the presence of Au bilayer cluster morphologies (figure 1) with catalytic activity for CO oxidation [1]. These bilayer Au structures have been shown to bind CO approximately 50% more strongly than bulk Au (figure 2) [15]. Furthermore oxygen either alone or in a reaction mixture has been shown to promote sintering of these bilayer Au structures (figure 3) [1]. A recent model study [16] of Au on a highly reduced TiO x ordered film grown on Mo(112) has demonstrated that a coordinatively unsaturated, continuous Au bilayer structure that precludes assess of the reactant to the support, exhibits an exceptional high activity for catalytic CO oxidation (figure 4). The activity of this Au bilayer film is more than an order of magnitude more active than any previous report on a per Au atom basis [16]. A key feature of Au grown on TiO x /Mo(112) is the strength of the interaction between the overlayer Au and the support comprised of strong bonding between Au and reduced Ti atoms of the TiO x support, yielding electron-rich Au [16]. These recent studies are entirely consistent with recent theoretical studies [17] that show the importance of reduced Ti defect sites at the boundary between Au clusters and a TiO 2 interface in determining the Au cluster shape and electronic properties via transfer of charge from the support to Au [18]. Finally a recent theoretical study [19] has shown that a Au-only reaction pathway for a TiO x supported Au bilayer cluster is energetically competitive with alternative pathways requiring reactant-support interactions.In summary the essential features of the interaction of Au with TiO 2 that lead to enhanced catalytic activity are: (1) wetting of the support by the cluster; (2) strong bonding between the Au atoms at the interface with surface defects (reduced Ti sites); (3) electron-rich Au; (4) annealing at temperatures in excess of 750 K, sufficient to create and mobilize surface and bulk defects...

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“…3a. The most common approach is metal deposition and growth from the gas phase (physical vapour deposition, PVD) 9,55,56 . The main advantages of PVD are its applicability to most materials, cleanliness of the samples prepared, and a broad range of available particle sizes.…”

Section: On the Development Of Model Catalystsmentioning

confidence: 99%

Model studies in heterogeneous catalysis at the microscopic level: from the structure and composition of surfaces to reaction kinetics

et al. 2006

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Heterogeneous catalysis is one of the fields of modern technology, in which a characterization of structural and chemical properties of solid surfaces at the microscopic level is of enormous importance. For a long time, such insights have been precluded by the complexity of most catalytically active materials. Recently, substantial progress has been made, however, toward a microscopic-level understanding of complex catalyst surfaces. We discuss the driving factors for these advancements, which are based on the development of new well-defined model systems as well as on advances in experimental technology and theory. Scrutinizing the example of planar model catalysts, we identify the process of linking structural and chemical information to microscopic reaction kinetics as a particular challenging aspect of today's work. We review the kinetic effects which may have an influence on the reaction kinetics on complex surfaces. As an example how structural and kinetic information can be correlated at the microscopic level we discuss the case of surface oxidation and oxygen induced restructuring of Pd nanoparticles as studied by molecular beam methods.

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Untitled

Cited by 155 publications

References 85 publications

Properties of oxide thin films and their adsorption behavior studied by scanning tunneling microscopy and conductance spectroscopy

Properties of oxide thin films and their adsorption behavior studied by scanning tunneling microscopy and conductance spectroscopy

?Catalytically active Au on Titania:? yet another example of a strong metal support interaction (SMSI)?

Model studies in heterogeneous catalysis at the microscopic level: from the structure and composition of surfaces to reaction kinetics

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