Publications in Scientific Journals:
D. Halwidl, W. Mayr-Schmölzer, D. Fobes, J. Peng, Z. Mao, M. Schmid, F. Mittendorfer, J. Redinger, U. Diebold:
"Ordered hydroxyls on Ca3Ru2O7(001)";
As complex ternary perovskite-type oxides are increasingly used in solid oxide fuel cells,
electrolysis and catalysis, it is desirable to obtain a better understanding of their surface
chemical properties. Here we report a pronounced ordering of hydroxyls on the cleaved (001)
surface of the Ruddlesden-Popper perovskite Ca3Ru2O7 upon water adsorption at 105 K and
subsequent annealing to room temperature. Density functional theory calculations predict the
dissociative adsorption of a single water molecule (Eads = 1.64 eV), forming an (OH)ads group
adsorbed in a Ca-Ca bridge site, with an H transferred to a neighboring surface oxygen atom,
Osurf. Scanning tunneling microscopy images show a pronounced ordering of the hydroxyls
with (2 × 1), c(2 × 6), (1 × 3), and (1 × 1) periodicity. The present work demonstrates the
importance of octahedral rotation and tilt in perovskites, for influencing surface reactivity,
which here induces the ordering of the observed OH overlayers.
Created from the Publication Database of the Vienna University of Technology.