Correlating Surface Crystal Orientation and Gas Kinetics in Perovskite Oxide Electrodes

© 2021 Wiley-VCH GmbH..

Solid-gas interactions at electrode surfaces determine the efficiency of solid-oxide fuel cells and electrolyzers. Here, the correlation between surface-gas kinetics and the crystal orientation of perovskite electrodes is studied in the model system La0.8 Sr0.2 Co0.2 Fe0.8 O3 . The gas-exchange kinetics are characterized by synthesizing epitaxial half-cell geometries where three single-variant surfaces are produced [i.e., La0.8 Sr0.2 Co0.2 Fe0.8 O3 /La0.9 Sr0.1 Ga0.95 Mg0.05 O3-δ /SrRuO3 /SrTiO3 (001), (110), and (111)]. Electrochemical impedance spectroscopy and electrical conductivity relaxation measurements reveal a strong surface-orientation dependency of the gas-exchange kinetics, wherein (111)-oriented surfaces exhibit an activity >3-times higher as compared to (001)-oriented surfaces. Oxygen partial pressure ( p O 2 )-dependent electrochemical impedance spectroscopy studies reveal that while the three surfaces have different gas-exchange kinetics, the reaction mechanisms and rate-limiting steps are the same (i.e., charge-transfer to the diatomic oxygen species). First-principles calculations suggest that the formation energy of vacancies and adsorption at the various surfaces is different and influenced by the surface polarity. Finally, synchrotron-based, ambient-pressure X-ray spectroscopies reveal distinct electronic changes and surface chemistry among the different surface orientations. Taken together, thin-film epitaxy provides an efficient approach to control and understand the electrode reactivity ultimately demonstrating that the (111)-surface exhibits a high density of active surface sites which leads to higher activity.

Medienart:

E-Artikel

Erscheinungsjahr:

2021

Erschienen:

2021

Enthalten in:

Zur Gesamtaufnahme - volume:33

Enthalten in:

Advanced materials (Deerfield Beach, Fla.) - 33(2021), 20 vom: 07. Mai, Seite e2100977

Sprache:

Englisch

Beteiligte Personen:

Gao, Ran [VerfasserIn]
Fernandez, Abel [VerfasserIn]
Chakraborty, Tanmoy [VerfasserIn]
Luo, Aileen [VerfasserIn]
Pesquera, David [VerfasserIn]
Das, Sujit [VerfasserIn]
Velarde, Gabriel [VerfasserIn]
Thoréton, Vincent [VerfasserIn]
Kilner, John [VerfasserIn]
Ishihara, Tatsumi [VerfasserIn]
Nemšák, Slavomír [VerfasserIn]
Crumlin, Ethan J [VerfasserIn]
Ertekin, Elif [VerfasserIn]
Martin, Lane W [VerfasserIn]

Links:

Volltext

Themen:

Electrochemical reactions
Epitaxial thin films
Half-cells
Journal Article
Perovskite oxides
Surface engineering

Anmerkungen:

Date Revised 20.05.2021

published: Print-Electronic

Citation Status PubMed-not-MEDLINE

doi:

10.1002/adma.202100977

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM323848311