Water adsorption and dissociation on the Au(321) stepped surface

• Tipo: Artigo em Revista Científica Internacional
• Data: 2010

Autores

Jose L C Fajin (Autor) FCUP; Natalia N D S Cordeiro (Autor) FCUP; Jose R B Gomes (Autor) Outra

Revista

Título: Journal of Molecular Structure: THEOCHEM

Vol. 946

Páginas: 51-56

ISSN: 0166-1280

Editora: Elsevier B.V.

Indexação

ISI Web of Knowledge - 13 Citações

Scopus - 12 Citações

Classificação Científica

FOS: Ciências exactas e naturais > Química

Outras Informações

ID Authenticus: P-003-7CS

DOI: 10.1016/j.theochem.2009.09.013

Abstract (EN): The H(2)O adsorption and dissociation on the zigzag stepped Au(3 2 1) surface was investigated using density functional theory and a periodic supercell approach. The water molecule interacts directly with the lowest coordinated gold atoms on the surface with one of its hydrogen atoms pointing towards the (1 1 1) terraces below. The adsorption energy with respect to the separated H(2)O and metal clean slab is -0.23 eV. The co-adsorption of the OH and H species is also more favorable with the fragments adsorbed nearby the step (bridge sites). The calculated interaction energy, with respect to gaseous water and to the clean slab, is 0.96 eV. The dissociation of water is endothermic by 1.19 eV and the barrier of the reaction is 1.33 eV. Finally, the rate constant for this reaction was determined for two different temperatures from transition state theory. The reaction rate constants are 1 x 10(-4) s(-1) and 2 x 10(0) s(-1) at 150 and 300 degrees C evidencing that the reaction of water dissociation is slow on the Au(3 2 1) surface. Importantly, these results suggest that the high performance of some Au-based catalysts in the water gas shift reaction (WGSR) is not related only with the presence of low-coordinated atoms, and that the support nature and structure, and support-gold interaction must have also an important role in the catalytic activity.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 6