TY - JOUR

T1 - Crystal-Orientation-Dependent Oxygen Exchange Kinetics on Mixed Conducting Thin-Film Surfaces Investigated by In Situ Studies

AU - Siebenhofer, Matthäus

AU - Riedl, Christoph

AU - Nenning, Andreas

AU - Raznjevic, Sergej

AU - Fellner, Felix

AU - Artner, Werner

AU - Zhang, Zaoli

AU - Rameshan, Christoph

AU - Fleig, Jürgen

AU - Kubicek, Markus

N1 - Publisher Copyright: © 2023 The Authors. Published by American Chemical Society.

PY - 2023/6/13

Y1 - 2023/6/13

N2 - The oxygen exchange kinetics and the surface chemistry of epitaxially grown, dense La0.6Sr0.4CoO3−δ (LSC) thin films in three different orientations, (001), (110), and (111), were investigated by means of in situ impedance spectroscopy during pulsed laser deposition (i-PLD) and near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS). i-PLD measurements showed that pristine LSC surfaces exhibit very fast surface exchange kinetics but revealed no significant differences between the specific orientations. However, as soon as the surfaces were in contact with acidic, gaseous impurities, such as S-containing compounds in nominally pure measurement atmospheres, NAP-XPS measurements revealed that the (001) orientation is substantially more susceptible to the formation of sulfate adsorbates and a concomitant performance decrease. This result is further substantiated by a stronger increase of the work function on (001)-oriented LSC surfaces upon sulfate adsorbate formation and by a faster performance degradation of these surfaces in ex situ measurement setups. This phenomenon has potentially gone unnoticed in the discussion of the interplay between the crystal orientation and the oxygen exchange kinetics and might have far-reaching implications for real solid oxide cell electrodes, where porous materials exhibit a wide variety of differently oriented and reconstructed surfaces.

AB - The oxygen exchange kinetics and the surface chemistry of epitaxially grown, dense La0.6Sr0.4CoO3−δ (LSC) thin films in three different orientations, (001), (110), and (111), were investigated by means of in situ impedance spectroscopy during pulsed laser deposition (i-PLD) and near-ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS). i-PLD measurements showed that pristine LSC surfaces exhibit very fast surface exchange kinetics but revealed no significant differences between the specific orientations. However, as soon as the surfaces were in contact with acidic, gaseous impurities, such as S-containing compounds in nominally pure measurement atmospheres, NAP-XPS measurements revealed that the (001) orientation is substantially more susceptible to the formation of sulfate adsorbates and a concomitant performance decrease. This result is further substantiated by a stronger increase of the work function on (001)-oriented LSC surfaces upon sulfate adsorbate formation and by a faster performance degradation of these surfaces in ex situ measurement setups. This phenomenon has potentially gone unnoticed in the discussion of the interplay between the crystal orientation and the oxygen exchange kinetics and might have far-reaching implications for real solid oxide cell electrodes, where porous materials exhibit a wide variety of differently oriented and reconstructed surfaces.

KW - mixed conducting oxides

KW - oxygen exchange

KW - pulsed laser deposition

KW - sulfate adsorbates

KW - work function

UR - http://www.scopus.com/inward/record.url?scp=85163473293&partnerID=8YFLogxK

U2 - 10.1021/acsaem.3c00870

DO - 10.1021/acsaem.3c00870

M3 - Article

AN - SCOPUS:85163473293

VL - 6.2023

SP - 6712

EP - 6720

JO - ACS Applied Energy Materials

JF - ACS Applied Energy Materials

SN - 2574-0962

IS - 12

ER -