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Temporal and thermal evolutions of surface Sr-segregation in pristine and atomic layer deposition modified La 0.6 Sr 0.4 CoO 3−δ epitaxial films
Ist Teil von
Journal of materials chemistry. A, Materials for energy and sustainability, 2018-12, Vol.6 (47), p.24378-24388
Erscheinungsjahr
2018
Quelle
Alma/SFX Local Collection
Beschreibungen/Notizen
The bulk-to-surface Sr segregation can seriously compromise the stability of oxygen electrocatalysis in La
1−x
Sr
x
CoO
3−δ
and limit its practical applications such as in solid oxide fuel cells. Here we show
via in situ
ambient pressure X-ray photoelectron spectroscopy (APXPS) that the surface Sr-segregation is a kinetically fast process and the equilibrium surface Sr-concentration follows Arrhenius law from 250 to 520 °C at a fixed
p
O2
= 1 × 10
−3
atm. We also show that application of a nanoscaled, atomic layer deposition (ALD) derived ZrO
2
overcoat can effectively suppress the Sr-segregation by reducing the surface concentration of oxygen vacancies. Electrochemical impedance spectroscopy (EIS) study further confirms that the ALD-ZrO
2
-coated LSCo epitaxial film exhibits a much lower and more stable polarization resistance than the uncoated one at 550 °C for >300 hours, suggesting that Sr-segregation is the source of the higher resistance.
Sprache
Englisch
Identifikatoren
ISSN: 2050-7488
eISSN: 2050-7496
DOI: 10.1039/C8TA08355J
Titel-ID: cdi_crossref_primary_10_1039_C8TA08355J
Format
–
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