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A Combined DFT and Statistical Mechanics Study for the CO Oxidation on the Au10–1 Cluster

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journal contribution
posted on 20.10.2011, 00:00 by Nima Nikbin, Giannis Mpourmpakis, Dionisios G. Vlachos
The CO oxidation reaction pathways on the negatively charged Au10–1 cluster are investigated using density functional theory calculations. Pre-exponential factors and reaction rate constants of each elementary step are calculated using statistical mechanics. Our results demonstrate that the reaction of CO and O2 on Au10–1 preferably proceeds through the formation of a 4-center intermediate rather than through O2 dissociation. The oxygen atom produced then reacts with adsorbed CO to form CO2. The rate-determining step of the CO oxidation appears to be the CO2 release from the 4-center intermediate. Interestingly, it is shown that gaseous CO2, which binds near an adsorbed atomic oxygen, forms easily a bidentate CO3 species that can poison the catalyst. The reverse reaction (carbonate decomposition) occurs with a rate constant comparable to the rate-determining step. A rate constant comparison for various reactant arrangements suggests a site-dependent reactivity, even for this subnanometer Au10–1 catalyst.