Regensburg 2019 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 75: Fundamentals of Catalysis I
O 75.1: Vortrag
Donnerstag, 4. April 2019, 10:30–10:45, H5
Coordination Effects in Model Rh1/Fe3O4 and Ir1/Fe3O4 Singe-Atom Catalysts — •Gareth Parkinson1, Jan Hulva1, Zdenek Jakub1, Matthias Meier1,2, Roland Bliem1, Cesare Franchini1,2, Michael Schmid1, and Ulrike Diebold1 — 1Institute of Applied Physics, TU Wien, Vienna, Austria — 2University of Vienna, Vienna, Austria
The coordination of the active site is thought to play a significant role in single atom catalysis, but precisely determining the local structure on high-area catalysts is extremely difficult. In this talk, I will report scanning probe microscopy, x-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD) results on the structure of Ir1/Fe3O4(001) and Rh1/Fe3O4(001) model single atom catalysts, and show that the coordination has dramatic consequences on CO adsorption. As prepared at room temperature, adatoms are twofold coordinated to surface oxygen, and hold on to CO until 650 K. Annealing the catalyst to successively higher temperatures results in five- and six-fold coordinated species, which adsorb CO even progressively more weakly. These results show that control of the local coordination environment is critical to design so-called single-atom catalysts, and that incorporation into the support can be as critical a deactivation mechanism for single atom catalysts as thermal sintering.