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Oxidation of Small Silver Clusters: A Density Functional Theory Study

Simon Klacar (Institutionen för teknisk fysik, Kemisk fysik ; Kompetenscentrum katalys (KCK)) ; Anders Hellman (Institutionen för teknisk fysik, Kemisk fysik ; Kompetenscentrum katalys (KCK)) ; Itai Panas (Institutionen för kemi- och bioteknik, Oorganisk miljökemi) ; Henrik Grönbeck (Institutionen för teknisk fysik, Kemisk fysik ; Kompetenscentrum katalys (KCK))
Journal of Physical Chemistry C (1932-7447). Vol. 114 (2010), 29, p. 12610-12617.
[Artikel, refereegranskad vetenskaplig]

The oxidation of small silver clusters (Ag-n, n <= 9) was investigated through electronic structure calculations based on density functional theory. The adsorption energies of molecular and dissociated adsorption show a pronounced odd/even alternation, with lower energies calculated for even-sized clusters. Molecular adsorption is favored for n <= 5, whereas dissociation is preferred for the larger sizes. Molecular oxygen is adsorbed in atop (Ag, Ag-2, Ag-6, Ag-8) or bridge (Ag-3, Ag-4, Ag-5, Ag-7, Ag-9) configurations, and atomic oxygen is preferably adsorbed in 3-fold hollow positions. Results for stoichiometric (Ag2nOn) clusters were compared to O-2 adsorption on Ag(111), and ab initio thermodynamics was used to estimate the temperature for the oxide-to-metal phase transition. The barrier for O-2 dissociation on Ag-8 was calculated to be higher than the corresponding barrier on Ag(111), which indicates a slower oxidation process. Adsorption of NOx onto the oxidized clusters was found to proceed through a formal reduction of the clusters; that is, NOx is adsorbed as NOx+1 with x = 1, 2.

Nyckelord: transition-metal clusters, molecular-oxygen, binding-energy, simple-models, adsorption, nox, chemisorption, hydrogen, surface, ag

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Denna post skapades 2010-08-11. Senast ändrad 2017-09-12.
CPL Pubid: 124366


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Institutioner (Chalmers)

Institutionen för teknisk fysik, Kemisk fysik (1900-2015)
Kompetenscentrum katalys (KCK)
Institutionen för kemi- och bioteknik, Oorganisk miljökemi (2005-2014)


Nanovetenskap och nanoteknik
Atom- och molekylfysik och optik

Chalmers infrastruktur

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