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Adsorbate-induced structural evolution changes the mechanism of CO oxidation on a Rh/Fe 3 O 4 (001) model catalyst

DOI: 10.1039/C9NR10087C DOI Help

Authors: Zdenek Jakub (TU Wien) , Jan Hulva (TU Wien) , Paul T. P. Ryan (Diamond Light Source; Imperial College London) , David A. Duncan (Diamond Light Source) , David J. Payne (Imperial College London) , Roland Bliem (TU Wien) , Manuel Ulreich (TU Wien) , Patrick Hofegger (TU Wien) , Florian Kraushofer (TU Wien) , Matthias Meier (TU Wien; University of Vienna) , Michael Schmid (TU Wien) , Ulrike Diebold (TU Wien) , Gareth S. Parkinson (TU Wien)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Nanoscale , VOL 55

State: Published (Approved)
Published: February 2020

Open Access Open Access

Abstract: The structure of a catalyst often changes in reactive environments, and following the structural evolution is crucial for the identification of the catalyst's active phase and reaction mechanism. Here we present an atomic-scale study of CO oxidation on a model Rh/Fe3O4(001) “single-atom” catalyst, which has a very different evolution depending on which of the two reactants, O2 or CO, is adsorbed first. Using temperature-programmed desorption (TPD) combined with scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS), we show that O2 destabilizes Rh atoms, leading to the formation of RhxOy clusters; these catalyze CO oxidation via a Langmuir–Hinshelwood mechanism at temperatures as low as 200 K. If CO adsorbs first, the system is poisoned for direct interaction with O2, and CO oxidation is dominated by a Mars-van-Krevelen pathway at 480 K.

Subject Areas: Chemistry

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