Nanoclusters of TiO2 wetted with gold

Park, K.T.; Meunier, Vincent; Pan, Minghu; Shelton, W. A.; Yu, Na; Plummer, E. W.

doi:10.1016/j.susc.2009.08.028

Cited by 9 publications

(10 citation statements)

References 29 publications

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“…[13,14] Segregation of Ti interstitials from the bulk to the surface and formation of additional layers (see e.g., refs. [15,16]), which is characteristic for reduced titania, might play an important role in the heterogeneous catalysis of gold.…”

Section: Introductionmentioning

confidence: 99%

“…[15,[46][47][48] The influence of these additional layers on the catalytic activity is still under discussion. [16,47] Wendt et al [12] proposed that Ti interstitials in the near subsurface regime should promote the catalytic activity of planar Au/TiO 2 model catalysts by lowering the energetic barrier of the CO oxidation. The presence of surface vacancies alone (e.g., created by sputtering with Ar ions) should not lead to enhanced conversion rates, but together with Ti interstitials, it should again have a preferential influence on the catalytic activity.…”

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confidence: 99%

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Planar Au/TiO₂ Model Catalysts: Fabrication, Characterization and Catalytic Activity

et al. 2010

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Different types of planar Au/TiO(2) model catalysts are produced on TiO(2)(110) single-crystal substrates and thin TiO(2) films on Ru(0001) by physical vapor deposition of gold under ultrahigh-vacuum (UHV) conditions or by micelle-based chemical routes. Both the Au nanoparticles and the support are characterized by surface-science-based methods (such as atomic force microscopy and X-ray photoelectron spectroscopy) as well as by transmission electron microscopy. Finally, the activity of the model catalysts in the CO oxidation reaction is analyzed in a microflow reactor. Au/TiO(2)(110) model catalysts with a stoichiometric TiO(2)(110) support exhibit only a low catalytic activity compared to those with a reduced crystal and Au/TiO(2) model catalysts with thin TiO(2) films on Ru(0001) as a substrate. The possible influence of Ti interstitials in the reduced TiO(2)(110) substrates on the CO oxidation activity is discussed.

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Section: Introductionmentioning

confidence: 99%

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confidence: 99%

Planar Au/TiO₂ Model Catalysts: Fabrication, Characterization and Catalytic Activity

et al. 2010

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“…These topographically distinctive dots have been interpreted as clusters of stoichiometric TiO 2 . Detailed discussions on their structures and their roles in cluster nucleation and growth were presented elsewhere (13).…”

Section: Figurementioning

confidence: 99%

“…This charge is related to the presence of stoichiometric and reduced TiO 2 clusters at the end of the line defects (13). In this form, δq 1;2 implicitly include depolarization effects related to the dielectric constant of inside the nanoclip.…”

Section: Modelmentioning

confidence: 99%

Evidence of Coulomb blockade behavior in a quasi-zero-dimensional quantum well on TiO ₂ surface

Meunier

Pan

Moreau

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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Line defects on the surface of rutile TiO 2 ð110Þ form in pairs separated by 1.2 nm creating a quantum well. The well is effectively closed by the presence of two charged structures at both ends separated by a distance in the 10-20 nm range. As expected for quantum confinement a long period oscillatory feature of the local density of states is observed and attributed to the formation of discrete quantum states inside the system. It is at first glance surprising that the lowest energy quantum state of the well can be observed at room temperature. The properties of the quantum state cannot be explained in an independent-electron, band-like theory. Instead, electron-electron correlation must be included to give a satisfactory picture of the spatial distribution of the charge density. Theory predicts charging energies of 1.30 eV and 1.14 eV for quantum well lengths of 14 nm and 16 nm, respectively, in good agreement with a classical calculation and the size dependence of the capacitance. This observation opens up the possibility of experimentally imaging the transition from a Coulomb blockade localized in a zero-dimensional system to an independent-particle or band-like behavior in an extended one-dimensional system.capacitor | Coulomb blockage | quantum confinement | titanium dioxide | scanning tunneling microscopy O ne of the most striking features of quantum mechanics is the distinctive electronic behavior associated with each level of dimensionality. Advances in scanning probe techniques coupled with the ability to prepare low-dimensional systems of unprecedented quality permits the direct observation of a number of manifestations of quantum mechanics in dimensionally confined systems (1). For example, a recent study revealed the presence of one-dimensional electronic states in the region between selforganized metallic nanowires on a semiconducting surface (2), a textbook illustration of an electron in a one-dimensional box. The famous picture of electron waves in a quantum corral is another beautiful example of imaging the density distribution of electrons in quantum confining structures (3-5). The electronic behavior of such systems may often be successfully understood within the independent-electron picture. When dimensionality is further reduced from quasi one-dimension (Q1D) to quasi zero-dimension (Q0D), electron-electron correlations are increasingly important and, in some instances, even dominate. In that case, the singleelectron picture breaks down. The failure of the single-electron description is exemplified by Coulomb blockade behavior (6, 7). Here, the presence of a net charge in the structure and the associated Coulomb repulsive potential hinder the addition of an extra electron. A convenient way to understand this behavior is through the concept of charging energy, similar to the energy stored on the plates of a conventional capacitor. For a typical spherical quantum well with tens of nanometer radius, the equivalent capacitance is on the order of the 10 −17 F, which corresponds to a charging ener...

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“…In addition to the sub-stoichiometric defects, partially reduced surfaces of TiO 2 show another type of defects: a nanometer-sized, bright dot [21]. It is imaged by STM as a 3 Å high protrusion on (110) surface (Figure 1(a),(b)).…”

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Defect-Driven Restructuring of TiO2 Surface and Modified Reactivity Toward Deposited Gold Atoms

et al. 2013

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A partially reduced TiO 2 surface exhibits increasingly complex nature when forming various defects, whose stoichiometry, structure and properties are markedly different from those of bulk TiO 2 . Using scanning tunneling microscopy and density functional theory, we investigate different types of surface defects formed by Ti interstitials on TiO 2 (110) and their reactivity toward deposited gold atoms. Sub-stoichiometric strands greatly enhance bonding of Au by transferring the excess charges from the reduced Ti 3+ onto the strands. Thus the sub-stoichiometric strands behave as strong electron donor sites toward reactants. On the contrary, fully stoichiometric nanoclusters provide increased Au bonding through its 1-coordinated oxygen, which acts as a strong electron acceptor site. Specific interactions between Au and defects as well as the implication of electron donor/acceptor complexes for catalytic reactions are discussed.

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Nanoclusters of TiO2 wetted with gold

Cited by 9 publications

References 29 publications

Planar Au/TiO₂ Model Catalysts: Fabrication, Characterization and Catalytic Activity

Planar Au/TiO₂ Model Catalysts: Fabrication, Characterization and Catalytic Activity

Evidence of Coulomb blockade behavior in a quasi-zero-dimensional quantum well on TiO ₂ surface

Defect-Driven Restructuring of TiO2 Surface and Modified Reactivity Toward Deposited Gold Atoms

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Nanoclusters of TiO2 wetted with gold

Cited by 9 publications

References 29 publications

Planar Au/TiO2 Model Catalysts: Fabrication, Characterization and Catalytic Activity

Planar Au/TiO2 Model Catalysts: Fabrication, Characterization and Catalytic Activity

Evidence of Coulomb blockade behavior in a quasi-zero-dimensional quantum well on TiO 2 surface

Defect-Driven Restructuring of TiO2 Surface and Modified Reactivity Toward Deposited Gold Atoms

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Product

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Planar Au/TiO₂ Model Catalysts: Fabrication, Characterization and Catalytic Activity

Planar Au/TiO₂ Model Catalysts: Fabrication, Characterization and Catalytic Activity

Evidence of Coulomb blockade behavior in a quasi-zero-dimensional quantum well on TiO ₂ surface