Enhancement of O2 dissociation on Au111 by adsorbed oxygen: implications for oxidation catalysis

We show that the dissociation probability of O2 on the reconstructed, Au111-herringbone surface is dramatically increased by the presence of some atomic oxygen on the surface. Specifically, at 400 K the dissociation probability of O2 on oxygen precovered Au111 is on the order of 10(-3), whereas ther...

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Bibliographic Details
Published in:Journal of the American Chemical Society 2005-06, Vol.127 (25), p.9267-9270
Main Authors: Deng, Xingyi, Min, Byoung Koun, Guloy, Amado, Friend, Cynthia M
Format: Article
Language:English
Subjects:
Adsorption
Catalysis
Electrons
Gold - chemistry
Nitrogen Dioxide - chemistry
Oxidation-Reduction
Oxygen - chemistry
Surface Properties
Temperature
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Summary:We show that the dissociation probability of O2 on the reconstructed, Au111-herringbone surface is dramatically increased by the presence of some atomic oxygen on the surface. Specifically, at 400 K the dissociation probability of O2 on oxygen precovered Au111 is on the order of 10(-3), whereas there is no measurable dissociation on clean Au111, establishing an upper bound for the dissociation probability of 10(-6). Atomic oxygen was deposited on the clean reconstructed Au111-herringbone surface using electron bombardment of condensed NO2 at 100 K. The dissociation probability for dioxygen was measured by exposing the surface to 18O2. Temperature programmed desorption (TPD) was used to quantify the amount of oxygen dissociation and to study the stability of the oxygen in all cases. Oxygen desorbs as O2 in a peak centered at 550 K with pseudo-first-order kinetics; i.e., the desorption peak does not shift with coverage. Our interpretation is that the coverage dependence of the activation energy for dissociation (deltaE(dis)) and/or preexponential factor (nu(d)) may be responsible for the unusual desorption kinetics, implying a possible energy barrier for O2 dissociation on Au111. These results are discussed in the context of Au oxidation chemistry and the relationship to supported Au nanoparticles.
ISSN:0002-7863