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D. Halwidl, B. Stöger, W. Mayr-Schmölzer, J. Pavelec, D. Fobes, J. Peng, Z. Mao, G. Parkinson, M. Schmid, F. Mittendorfer, J. Redinger, U. Diebold:
"Adsorption of water at the SrO surface of ruthenates";
Nature Materials, 15 (2016), 450 - 456.

Although perovskite oxides hold promise in applications ranging from solid oxide fuel cells to catalysts, their surface chemistry
is poorly understood at the molecular level. Herewe followthe formation of the first monolayer ofwater at the (001) surfaces of
Srn+1RunO3n+1 (n=1, 2) using low-temperature scanning tunnelling microscopy, X-ray photoelectron spectroscopy, and density
functional theory. These layered perovskites cleave between neighbouring SrO planes, yielding almost ideal, rocksalt-like
surfaces. An adsorbed monomer dissociates and forms a pair of hydroxide ions. The OH stemming from the original molecule
stays trapped at Sr-Sr bridge positions, circling the surface OH with a measured activation energy of 187 ± 10meV. At higher
coverage, dimers of dissociated water assemble into one-dimensional chains and form a percolating network where water
adsorbs molecularly in the gaps. Our work shows the limitations of applying surface chemistry concepts derived for binary
rocksalt oxides to perovskites.