title: Adsorption of water at the SrO surface of ruthenates.
abstract: 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. Here we follow the formation of the first monolayer of water at the (001) surfaces of Sr(n+1)Ru(n)O3(n+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 ± 10 meV. 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.
authors.affiliation: Institute of Applied Physics, TU Wien, Wiedner Hauptstrasse 8-10/134, A-1040 Vienna, Austria.
authors.forename: Daniel
authors.initials: D
authors.lastname: Halwidl
authors.affiliation: Institute of Applied Physics, TU Wien, Wiedner Hauptstrasse 8-10/134, A-1040 Vienna, Austria.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Stöger
authors.affiliation: Institute of Applied Physics, TU Wien, Wiedner Hauptstrasse 8-10/134, A-1040 Vienna, Austria.|Center for Computational Materials Science, TU Wien, Wiedner Hauptstrasse 8-10/134, A-1040 Vienna, Austria.
authors.forename: Wernfried
authors.initials: W
authors.lastname: Mayr-Schmölzer
authors.affiliation: Institute of Applied Physics, TU Wien, Wiedner Hauptstrasse 8-10/134, A-1040 Vienna, Austria.
authors.forename: Jiri
authors.initials: J
authors.lastname: Pavelec
authors.affiliation: Department of Physics and Engineering Physics, Tulane University, New Orleans, LA 70118, USA.
authors.forename: David
authors.initials: D
authors.lastname: Fobes
authors.affiliation: Department of Physics and Engineering Physics, Tulane University, New Orleans, LA 70118, USA.
authors.forename: Jin
authors.initials: J
authors.lastname: Peng
authors.affiliation: Department of Physics and Engineering Physics, Tulane University, New Orleans, LA 70118, USA.
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Mao
authors.affiliation: Institute of Applied Physics, TU Wien, Wiedner Hauptstrasse 8-10/134, A-1040 Vienna, Austria.
authors.forename: Gareth S
authors.initials: GS
authors.lastname: Parkinson
authors.affiliation: Institute of Applied Physics, TU Wien, Wiedner Hauptstrasse 8-10/134, A-1040 Vienna, Austria.
authors.forename: Michael
authors.initials: M
authors.lastname: Schmid
authors.affiliation: Institute of Applied Physics, TU Wien, Wiedner Hauptstrasse 8-10/134, A-1040 Vienna, Austria.|Center for Computational Materials Science, TU Wien, Wiedner Hauptstrasse 8-10/134, A-1040 Vienna, Austria.
authors.forename: Florian
authors.initials: F
authors.lastname: Mittendorfer
authors.affiliation: Institute of Applied Physics, TU Wien, Wiedner Hauptstrasse 8-10/134, A-1040 Vienna, Austria.|Center for Computational Materials Science, TU Wien, Wiedner Hauptstrasse 8-10/134, A-1040 Vienna, Austria.
authors.forename: Josef
authors.initials: J
authors.lastname: Redinger
authors.affiliation: Institute of Applied Physics, TU Wien, Wiedner Hauptstrasse 8-10/134, A-1040 Vienna, Austria.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Diebold