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Título: | Theoretical studies of the adsorption of CO and C on Ni(111) and Ni/CeO2(111): Evidence of a strong metal-support interaction |
Autor: | Carrasco Rodríguez, Javier; Barrio Pliego, Laura CSIC ORCID; Liu, P.; Rodríguez, José A.; Ganduglia-Pirovano, M. V. CSIC ORCID | Fecha de publicación: | 2013 | Editor: | American Chemical Society | Citación: | Journal of Physical Chemistry C 117(16): 8241-8250 (2013) | Resumen: | The catalytic CO methanation reaction on Ni/CeO2(111) systems is known to depend on Ni coverage: at medium and large coverages, Ni/CeO 2(111) surfaces are able to catalyze methane production, whereas at small coverage they become efficient catalysts for the water-gas shift reaction. Electronic structure, geometries, and the adsorption of C and CO on small Nin (n = 1 and 4) particles deposited on CeO2(111) have been studied using density functional theory (DFT) with the DFT+U approach and compared with Ni(111) and CeO2(111). The most stable Ni4 cluster has a pyramidal structure (pyr-Ni4), and a planar rhombohedral structure (r-Ni4) is less stable by ∼0.2 eV. Metallic Ni particles are partially oxidized (Ni2+/Ni1+) upon deposition on the ceria support, which is partially reduced. C species are strongly bound on Ni(111), whereas on Ni/CeO2(111), and on the bare support, oxidative adsorption (C + CeO2 → CO + CeO 2-x) is mostly preferred, opening a Mars-van Krevelen mechanism to prevent coke formation. The exothermicity of nonoxidative adsorption of C on nickel sites follows the trend: Ni1/CeO2(111) < pyr-Ni4/CeO2(111) < Ni(111). On these systems, CO adsorption is nonoxidative. The C-O bond strength follows the inverse trend of the nonoxidative adsorption of C: Ni(111) < pyr-Ni4/CeO 2(111) < Ni1/CeO2(111). The stronger C-O bond found for the CO/Ni1/CeO2(111) system compared with CO/Ni(111) provides an explanation of the Ni coverage dependence reported for the CO methanation reaction on Ni/CeO2(111) catalysts. The strong electronic perturbations in the Ni1 adatoms produce a drastic change in their chemical properties. © 2013 American Chemical Society. | Versión del editor: | https://doi.org/10.1021/jp400430r | URI: | http://hdl.handle.net/10261/181773 | DOI: | 10.1021/jp400430r | ISSN: | 1932-7447 | E-ISSN: | 1932-7455 |
Aparece en las colecciones: | (ICP) Artículos |
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