In Situ and Theoretical Studies for the Dissociation of Water on an Active Ni/CeO sub(2) Catalyst: Importance of Strong Metal-Support Interactions for the Cleavage of O-H Bonds
Water dissociation is crucial in many catalytic reactions on oxide-supported transition-metal catalysts. Supported by experimental and density-functional theory results, the effect of the support on O--H bond cleavage activity is elucidated for nickel/ceria systems. Ambient-pressure O1s photoemissio...
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Veröffentlicht in: | Angewandte Chemie International Edition 2015-03, Vol.54 (13), p.3917-3921 |
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Sprache: | eng |
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Zusammenfassung: | Water dissociation is crucial in many catalytic reactions on oxide-supported transition-metal catalysts. Supported by experimental and density-functional theory results, the effect of the support on O--H bond cleavage activity is elucidated for nickel/ceria systems. Ambient-pressure O1s photoemission spectra at low Ni loadings on CeO sub(2)(111) reveal a substantially larger amount of OH groups as compared to the bare support. Computed activation energy barriers for water dissociation show an enhanced reactivity of Ni adatoms on CeO sub(2)(111) compared with pyramidal Ni sub(4) particles with one Ni atom not in contact with the support, and extended Ni(111) surfaces. At the origin of this support effect is the ability of ceria to stabilize oxidized Ni super(2+) species by accommodating electrons in localized f-states. The fast dissociation of water on Ni/CeO sub(2) has a dramatic effect on the activity and stability of this system as a catalyst for the water-gas shift and ethanol steam reforming reactions. By accommodating electrons in localized f-states, ceria stabilizes Ni super(2+) species that possess unique activity for the cleavage of O--H bonds. These species play an important role in the water-gas shift reaction and the steam reforming of alcohols over Ni/CeO sub(2) catalysts. |
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ISSN: | 1433-7851 1521-3773 |
DOI: | 10.1002/anie.201410697 |