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Oxygen-Promoted Methane Activation on Copper

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journal contribution
posted on 2017-11-01, 00:00 authored by Tianchao Niu, Zhao Jiang, Yaguang Zhu, Guangwen Zhou, Matthijs A. van Spronsen, Samuel A. Tenney, J. Anibal Boscoboinik, Dario Stacchiola
The role of oxygen in the activation of C–H bonds in methane on clean and oxygen-precovered Cu(111) and Cu2O­(111) surfaces was studied with combined in situ near-ambient-pressure scanning tunneling microscopy and X-ray photoelectron spectroscopy. Activation of methane at 300 K and “moderate pressures” was only observed on oxygen-precovered Cu(111) surfaces. Density functional theory calculations reveal that the lowest activation energy barrier of C–H on Cu(111) in the presence of chemisorbed oxygen is related to a two-active-site, four-centered mechanism, which stabilizes the required transition-state intermediate by dipole–dipole attraction of O–H and Cu–CH3 species. The C–H bond activation barriers on Cu2O­(111) surfaces are large due to the weak stabilization of H and CH3 fragments.

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