SKM 2021 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 7: Thin Oxides and Organic Thin Films (joint session DS/CPP)
DS 7.1: Vortrag
Donnerstag, 30. September 2021, 15:15–15:30, H5
Hybrid electronic states in epitaxially layered perovskite oxide electrocatalysts for water electrolysis — •Lisa Heymann1, Moritz Weber1, Marcus Wohlgemuth1, Felix Gunkel1, and Christoph Baeumer1,2 — 1Peter Gruenberg Institute and JARA-FIT, Forschungszentrum Juelich GmbH, Germany — 2MESA+ Institute for Nanotechnology, University of Twente, Netherlands
In electrochemical water splitting catalyzed by perovskite oxides (ABO3), the B-O hybridization degree has a major impact on the electrocatalytic activity. Additionally, space charge layers at the interface to the electrolyte may hamper the electron transfer into the electrode, complicating the analysis of hybridization phenomena. The goal in this work was to explore whether A site doping in cobaltites (ACoO3) has a major impact on the oxygen evolution reaction (OER) through a different degree of hybridization or the extend of a surface space charge layer. We investigated La0.6Sr0.4CoO3 and LaCoO3 bilayer structures in epitaxial thin films that enabled us to create a near surface depth profile of both, the hybridization degree and the doping concentration confirmed by x-ray photoelectron spectroscopy (XPS). In a Mott Schottky (MS) analysis, we showed that in the OER potential regime the catalytic activity is not limited by a space charge layer. Therefore, we can correlate the observed OER activity trend to the degree of hybridization in cobaltites. The combined XPS and MS analysis enables to differentiate between the influence of the hybridization degree and intrinsic space charge layers, which are indistinguishable in a sole physical or electrochemical characterization.