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| 2. |
- Knapp, M., et al.
(author)
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Unusual process of water formation on RuO2(110) by hydrogen exposure at room temperature
- 2006
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In: The Journal of Physical Chemistry Part B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 110:29, s. 14007-14010
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Journal article (peer-reviewed)abstract
- The reduction mechanism of the RuO2(110) surface by molecular hydrogen exposure is unraveled to an unprecedented level by a combination of temperature programmed reaction, scanning tunneling microscopy, high-resolution core level shift spectroscopy, and density functional theory calculations. We demonstrate that even at room temperature hydrogen exposure to the RuO2(110) surface leads to the formation of water. In a two-step process, hydrogen saturates first the bridging oxygen atoms to form (O-br-H) species and subsequently part of these O-br-H groups move to the undercoordinated Ru atoms where they form adsorbed water. This latter process is driven by thermodynamics leaving vacancies in the bridging O rows.
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| 3. |
- Over, H, et al.
(author)
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Visualization of atomic processes on ruthenium dioxide using scanning tunneling microscopy
- 2004
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In: ChemPhysChem. - : Wiley. - 1439-7641 .- 1439-4235. ; 5:2, s. 167-174
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Research review (peer-reviewed)abstract
- The visualization of surface reactions on the atomic scale provides direct insight into the microscopic reaction steps taking place in a catalytic reaction at a (model) catalyst's surface. Employing the technique of scanning tunneling microscopy (STM), we investigated the CO oxidation reaction over the RuO2(110) and RuO2(100) surfaces. For both surfaces the protruding bridging O atoms are imaged in STM as bright features. The reaction mechanism is identical on both orientations of RuO2. CO molecules adsorb on the undercoordinated surface Ru atoms from where they recombine with undercoordinated O atoms to form CO2 at the oxide surface. In contrast to the RuO2(110) surface, the RuO2(100) surface stabilizes also a catalytically inactive c(2 x 2) phase may play an important role in the deactivation of RuO2 catalysts in the electrochemical Cl-2 evolution and other heterogeneous reactions.
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| 4. |
- He, YB, et al.
(author)
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Ru(0001) model catalyst under oxidizing and reducing reaction conditions: in-situ high-pressure surface X-ray diffraction study
- 2005
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In: The Journal of Physical Chemistry Part B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 109:46, s. 21825-21830
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Journal article (peer-reviewed)abstract
- With surface X-ray diffraction (SXRD) using a high-pressure reaction chamber we investigated in-situ the oxidation of the Ru(0001) model catalyst under various reaction conditions, starting from a strongly oxidizing environment to reaction conditions typical for CO oxidation. With a mixture Of O-2 and CO (stoichiometry, 2:1) the partial pressure of oxygen has to be increased to 20 mbar to form the catalytically active RuO2(110) oxide film, while in pure oxygen environment a pressure of 10(-5) mbar is already sufficient to oxidize the Ru(0001) surface. For preparation temperatures in the range of 550-630 K a self-limiting RUO2(110) film is produced with a thickness of 1.6 nm. The RuO2(110) film grows self-acceleratedly after an induction period. The RuO2 films on Ru(0001) can readily be reduced by H-2 and CO exposures at 415 K, without an induction period.
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| 5. |
- Knapp, M., et al.
(author)
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Complex interaction of hydrogen with the RuO2(110) surface
- 2007
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In: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 111:14, s. 5363-5373
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Journal article (peer-reviewed)abstract
- Using a variety of dedicated surface sensitive techniques, we studied the interaction of hydrogen with bare and adsorbate modified RuO2(110) surfaces on the atomic scale. Hydrogen interacts strongly with the undercoordinated O atoms, thereby forming hydroxyl groups and passivating available oxygen species on the oxide surface, for instance, for the catalytic CO oxidation reaction. Temperature programmed reaction and desorption elucidate the complex reaction behavior of hydrogen with O precovered RuO2(110), including the hydrogen transfer reaction between the different kinds of undercoordinated surface oxygen atoms. Hydroxyl, water species, and hydrogen transfer are identified with high-resolution O1s core level spectroscopy by comparison with density functional theory (DFT) calculated O1s core level shifts. DFT calculations provide adsorption energies, atomic geometries, as well as diffusion barriers of H atoms on the RuO2(110) surface.
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| 6. |
- Seitsonen, A. P., et al.
(author)
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Reaction mechanism of ammonia oxidation over RuO2(110): A combined theory/experiment approach
- 2009
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In: Surface Science. - : Elsevier BV. - 0039-6028. ; 603:18, s. 113-116
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Journal article (peer-reviewed)abstract
- Combining state-of-the-art density functional theory (DFT) calculations with high resolution core level shift spectroscopy experiments we explored the reaction mechanism of the ammonia oxidation reaction over RuO2(1 1 0). The high catalytic activity of RuO2(1 1 0) is traced to the low activation energies for the successive hydrogen abstractions of ammonia by on-top O (less than 73 kJ/mol) and the low activation barrier for the recombination of adsorbed O and N (77 kJ/mol) to form adsorbed NO. The NO desorption is activated by 121 kJ/mol and represents therefore the rate determining step in the ammonia oxidation reaction over RuO2 (1 1 0). (C) 2009 Elsevier B.V. All rights reserved.
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| 7. |
- Zweidinger, S., et al.
(author)
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Reaction mechanism of the oxidation of HCl over RuO2(110)
- 2008
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In: Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 112:27, s. 9966-9969
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Journal article (peer-reviewed)abstract
- High-resolution core-level shift spectroscopy and temperature-programmed reaction experiments together with density functional theory calculations reveal that the oxidation of HCl with oxygen producing Cl-2 and water proceeds on the chlorine-stabilized RuO2(110)surface via a one-dimensional Langmuir-Hinshelwood mechanism. The recombination of two adjacent chlorine atoms on the catalyst's surface constitutes the rate-determining step in this novel Deacon-like process.
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