title: Enhancing electrochemical water-splitting kinetics by polarization-driven formation of near-surface iron(0): an in situ XPS study on perovskite-type electrodes.
abstract: In the search for optimized cathode materials for high-temperature electrolysis, mixed conducting oxides are highly promising candidates. This study deals with fundamentally novel insights into the relation between surface chemistry and electrocatalytic activity of lanthanum ferrite based electrolysis cathodes. For this means, near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS) and impedance spectroscopy experiments were performed simultaneously on electrochemically polarized La0.6 Sr0.4 FeO3-δ (LSF) thin film electrodes. Under cathodic polarization the formation of Fe(0) on the LSF surface could be observed, which was accompanied by a strong improvement of the electrochemical water splitting activity of the electrodes. This correlation suggests a fundamentally different water splitting mechanism in presence of the metallic iron species and may open novel paths in the search for electrodes with increased water splitting activity.
authors.affiliation: Vienna University of Technology, Institute of Chemical Technologies and Analytics, Getreidemarkt 9/164-EC, 1060 Vienna (Austria). alexander.opitz@tuwien.ac.at.
authors.forename: Alexander K
authors.initials: AK
authors.lastname: Opitz
authors.forename: Andreas
authors.initials: A
authors.lastname: Nenning
authors.forename: Christoph
authors.initials: C
authors.lastname: Rameshan
authors.forename: Raffael
authors.initials: R
authors.lastname: Rameshan
authors.forename: Raoul
authors.initials: R
authors.lastname: Blume
authors.forename: Michael
authors.initials: M
authors.lastname: Hävecker
authors.forename: Axel
authors.initials: A
authors.lastname: Knop-Gericke
authors.forename: Günther
authors.initials: G
authors.lastname: Rupprechter
authors.forename: Jürgen
authors.initials: J
authors.lastname: Fleig
authors.forename: Bernhard
authors.initials: B
authors.lastname: Klötzer
mesh_terms: D017610:Calcium Compounds / Q000737:chemistry*; D055664:Electrochemical Techniques; D004566:Electrodes; D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D007811:Lanthanum / Q000737:chemistry; D010087:Oxides / Q000737:chemistry*; D056951:Photoelectron Spectroscopy; D013324:Strontium / Q000737:chemistry; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D017610:Calcium Compounds; D010087:Oxides; D014867:Water; C059910:perovskite; D007811:Lanthanum; D014025:Titanium; D007501:Iron; D013324:Strontium
keywords: electrocatalysis; heterogeneous catalysis; perovskites; solid oxide electrolysis cells; thin-film electrodes