Adsorption of O\ :sub:`2` and oxidation of CO at Au nanoparticles
supported by TiO\ :sub:`2`\ (110).

Adsorption of O\ :sub:`2` and oxidation of CO at Au nanoparticles supported by TiO\ :sub:`2`\ (110).
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by L. M. Molina, M. D. Rasmussen, and B. Hammer

J. Chem. Phys. **120**, 7673 (2004).

Abstract
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Density functional theory calculations are performed for the adsorption
of O\ :sub:`2`, coadsorption of CO, and the CO+O\ :sub:`2` reaction at
the interfacial perimeter of nanoparticles supported by rutile
TiO\ :sub:`2`\ (110). Both stoichiometric and reduced TiO\ :sub:`2`
surfaces are considered, with various arrangements of the supported Au
particles with respect to the substrate vacancies. Rather stable binding
configurations are found for the O\ :sub:`2` adsorbed either at the
trough Ti atoms or leaning against the Au particles. The presence of a
supported Au particle strongly stabilizes the adsorption of O\ :sub:`2`.
A sizable electronic charge transfer from the Au to the O\ :sub:`2` is
found together with a concomitant electronic polarization of the support
meaning that the substrate is mediating the charge transfer. The
O\ :sub:`2` attains two different charge states, with either one or two
surplus electrons depending on the precise O\ :sub:`2` adsorption site
at or in front of the Au particle. From the least charged state, the
O\ :sub:`2` can react with CO adsorbed at the edge sites of the Au
particles leading to the formation of CO\ :sub:`2` with very low (0.15
eV) energy barriers.