Dataset Information

The Chemical Evolution of the La0.6Sr0.4CoO3-? Surface Under SOFC Operating Conditions and Its Implications for Electrochemical Oxygen Exchange Activity.

ABSTRACT: Owing to its extraordinary high activity for catalysing the oxygen exchange reaction, strontium doped LaCoO3 (LSC) is one of the most promising materials for solid oxide fuel cell (SOFC) cathodes. However, under SOFC operating conditions this material suffers from performance degradation. This loss of electrochemical activity has been extensively studied in the past and an accumulation of strontium at the LSC surface has been shown to be responsible for most of the degradation effects. The present study sheds further light onto LSC surface changes also occurring under SOFC operating conditions. In-situ near ambient pressure X-ray photoelectron spectroscopy measurements were conducted at temperatures between 400 and 790 °C. Simultaneously, electrochemical impedance measurements were performed to characterise the catalytic activity of the LSC electrode surface for O2 reduction. This combination allowed a correlation of the loss in electro-catalytic activity with the appearance of an additional La-containing Sr-oxide species at the LSC surface. This additional Sr-oxide species preferentially covers electrochemically active Co sites at the surface, and thus very effectively decreases the oxygen exchange performance of LSC. Formation of precipitates, in contrast, was found to play a less important role for the electrochemical degradation of LSC.

SUBMITTER: Opitz AK

PROVIDER: S-EPMC6404788 | biostudies-literature | 2018

REPOSITORIES: biostudies-literature

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Publications

The Chemical Evolution of the La0.6Sr0.4CoO3-δ Surface Under SOFC Operating Conditions and Its Implications for Electrochemical Oxygen Exchange Activity.

Opitz Alexander K AK Rameshan Christoph C Kubicek Markus M Rupp Ghislain M GM Nenning Andreas A Götsch Thomas T Blume Raoul R Hävecker Michael M Knop-Gericke Axel A Rupprechter Günther G Klötzer Bernhard B Fleig Jürgen J

Topics in catalysis 20181020 20

Owing to its extraordinary high activity for catalysing the oxygen exchange reaction, strontium doped LaCoO3 (LSC) is one of the most promising materials for solid oxide fuel cell (SOFC) cathodes. However, under SOFC operating conditions this material suffers from performance degradation. This loss of electrochemical activity has been extensively studied in the past and an accumulation of strontium at the LSC surface has been shown to be responsible for most of the degradation effects ...[more]

PMID: 30930590

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Project description:Calcitic valves of non-marine ostracodes are important geochemical archives. Investigations of the relationship between the ranges of oxygen and carbon isotope values of modern ostracode populations and their host water provide important information on local or regional conditions and influences. Here we present the first δ18Oostracode and δ13C of the freshwater ostracode species Cytheridella ilosvayi along with the isotopic composition of the waters in which the ostracodes calcified, δDwater, δ18Owater, δ13CDIC values-covering a large geographical range (Florida to Brazil). With this data we extended a newly developed approach based on the estimation of δ18O values of monthly equilibrium calcites as references for the interpretation of δ18Oostracode values. The expected apparent oxygen isotope fractionation between CaCO3 and H2O is correlated with temperature with smaller values occurring at higher temperatures as valid at isotope equilibrium (δ18Ocalcite_eq). Uncertainties about the expected equilibrium calcites derive from incomplete knowledge of high-frequency variations of the water bodies caused by interplay of mixing, evaporation, and temperature. Coincidence between δ18Oostracode and δ18Ocalcite_eq is restricted to few months indicating a seasonal calcification of Cytheridella. There is a characteristic pattern in its difference between mean δ18Oostracode and δ18Ocalcite_eq which implies that Cytheridella provides a synchronous life cycle in its geographical range with two calcification periods in spring (May, June) and autumn (October). This ubiquitous life cycle of Cytheridella in the entire study area is considered to be phylogenetically inherited. It might have originally been adapted to environmental conditions but has been conserved during the migration and radiation of the group over the Neotropical realm.Supplementary informationThe online version contains supplementary material available at 10.1007/s10533-022-00917-9.

Dataset Information

The Chemical Evolution of the La0.6Sr0.4CoO3-? Surface Under SOFC Operating Conditions and Its Implications for Electrochemical Oxygen Exchange Activity.

Publications

The Chemical Evolution of the La<sub>0.6</sub>Sr<sub>0.4</sub>CoO<sub>3-δ</sub> Surface Under SOFC Operating Conditions and Its Implications for Electrochemical Oxygen Exchange Activity.

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