By a combination of electron paramagnetic resonance spectroscopy, finite-temperature ab initio simulations, and electronic structure analyses, the activation of molecular dioxygen at the interface of gold nanoparticles and titania in Au/TiO 2 catalysts is explained at the atomic scale by tracing processes down to the molecular orbital picture. Direct evidence is provided that excess electrons in TiO 2 , for example created by photoexcitation of the semiconductor, migrate to the gold particles and from there to oxygen molecules adsorbed at gold/titania perimeter sites. Superoxide species are formed more efficiently in this way than on the bare TiO 2 surface. This catalytic effect of the gold nanoparticles is attributed to a weakening of the internal O-O bond, leading to a preferential splitting of the molecule at shorter bond lengths together with a 70% decrease of the dissociation free energy barrier compared to the non-catalyzed case on bare TiO 2 . The findings are an important step forward in the clarification of the role of gold in (photo)catalytic processes.
CITATION STYLE
Siemer, N., Lüken, A., Zalibera, M., Frenzel, J., Muñoz-Santiburcio, D., Savitsky, A., … Strunk, J. (2018). Atomic-Scale Explanation of O 2 Activation at the Au-TiO 2 Interface. Journal of the American Chemical Society, 140(51), 18082–18092. https://doi.org/10.1021/jacs.8b10929
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