Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 49: Metal Substrates: Structure, Epitaxy and Growth
O 49.7: Vortrag
Mittwoch, 18. März 2015, 12:00–12:15, MA 042
Ultra-thin stepped iron oxide films on high index Pt surfaces — •Elin Grånäs1,2, Niclas Johansson1, Mohammad A. Arman1, Jacek Osiecki3, Karina Thånell3, Jesper N. Andersen1,3, Joachim Schnadt1, and Jan Knudsen1,3 — 1Division of Synchrotron Radiation Research, Lund Universiy, Sweden — 2Deutsches-Elektron Synchrotron (DESY), Hamburg, Germany — 3MAX IV Laboratory, Lund University, Sweden
Iron oxide films grown on metal surfaces show high catalytic activity for reactions such as CO oxidation and the water-gas shift, and it has been suggested that the high activity is due to under-coordinated Fe atoms at the edge of FeO islands[1]. Whether the metal substrate is essential for the activity of the edge sites remain an open question and the few and heterogeneous edge sites present on FeO islands make it difficult to characterize them with chemically sensitive techniques like X-ray photoelectron spectroscopy (XPS).
We have grown FeO films on Pt(322), producing films with a very high density of homogenous FeO-FeO edge sites. Scanning tunneling microscopy show that approx. 20 % of the sites are edge sites. In water adsorption studies on the stepped FeO film we observe an enhanced ability to split water compared to planar FeO. As the Pt(322) substrate is fully covered by stepped FeO we assign the high water splitting ability to the pure FeO-FeO step site.
[1] L. Xu, Z. Wu et al., J. Phys. Chem. C 115, 14290 (2011)