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Role of Oxide Reducibility in the Deoxygenation of Phenol on Ruthenium Clusters Supported on the Anatase Titania (1 0 1) Surface
Author(s) -
Chen HsinYi Tiffany,
Pacchioni Gianfranco
Publication year - 2016
Publication title -
chemcatchem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.497
H-Index - 106
eISSN - 1867-3899
pISSN - 1867-3880
DOI - 10.1002/cctc.201600457
Subject(s) - deoxygenation , anatase , chemistry , adsorption , phenol , photochemistry , oxide , inorganic chemistry , molecule , ruthenium , stoichiometry , photocatalysis , catalysis , organic chemistry
The deoxygenation of phenol on stoichiometric and reduced Ru 10 /TiO 2 anatase (1 0 1) surfaces has been studied by using DFT with the Hubbard correction (DFT+U). If the molecule orients with the OH group towards the metal–oxide interface, the direct deoxygenation of phenol can occur. However, on the stoichiometric TiO 2 surface, the reaction is thermodynamically unfavorable. Two kinds of reduced surfaces have been considered: one in which Ti 3+ centers are generated by hydrogen addition, and a second one in which a water molecule is removed from a hydroxylated surface with the formation of O vacancies and Ti 3+ centers. On the surface reduced by hydrogen addition (Ti 3+ ions), the phenol molecular and dissociative adsorptions (C 6 H 5 +OH fragments) become isoenergetic; the barrier to dissociate the C−OH bond is 1.19 eV, which indicates a possible channel for the deoxygenation of phenol. On the surface reduced by O vacancies, the dissociative adsorption is 0.22 eV more stable than the molecular adsorption, which indicates a thermodynamically favorable process; however, the C−OH activation energy is higher, 1.50 eV. The results show that the C−O scission can be an important step towards the direct deoxygenation. The reduction of the surface facilitates the direct deoxygenation of phenol significantly.