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Enhanced catalytic activity of nanostructured, A-site deficient (La0.7Sr0.3)0.95(Co0.2Fe0.8)O3−δ for SOFC cathodes

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Title: Enhanced catalytic activity of nanostructured, A-site deficient (La0.7Sr0.3)0.95(Co0.2Fe0.8)O3−δ for SOFC cathodes
Authors: Celikbilek, O
Thieu, C-A
Agnese, F
Cali, E
Lenser, C
Menzler, N
Son, J-W
Skinner, S
Djurado, E
Item Type: Journal Article
Abstract: Lower operating temperatures (≤650 °C) of solid oxide fuel cells (SOFCs) are sought in order to decrease the system costs and improve material compatibility and durability issues. Here, we report A-site deficient (La0.7Sr0.3)0.95(Co0.2Fe0.8)O3−δ (LSCF) perovskite film as a potential high-performance cathode with microstructural details at the nanometre length scale. This cathode exhibits area specific resistance values of as low as 0.037 and 0.1 Ω cm2 in a symmetrical cell and peak power densities of 1.4 and 1.0 W cm−2 in a Ni/YSZ anode-supported cell at 650 and 600 °C, respectively. These values are among the highest reported data for LSCF-type cathodes. X-ray diffraction and electron microscopy analyses revealed a closely related two-phase perovskite structure for LSCF and a well-dispersed, nanoscale B-site spinel phase (CoFeOx) decorating the LSCF surfaces. Detailed investigations were carried out to correlate the surface to bulk elemental composition changes on the film, the catalytic activity of the spinel phase and the crystal structures of the constituents with the oxygen reduction reaction (ORR) kinetics. The oxygen transport parameters calculated from the electrochemical impedance spectra indicate an increase by one-to-two-orders of magnitude in the oxygen surface-exchange coefficient in comparison to nominally stoichiometric, state-of-the-art La0.6Sr0.4Co0.2Fe0.8O3−δ. Such substantial improvements in the electrode performance were attributed to the catalytically active B-site spinel phase precipitated as a result of the A-site deficiency and to the very high active surface area of the film.
Issue Date: 21-Nov-2019
Date of Acceptance: 15-Oct-2019
URI: http://hdl.handle.net/10044/1/74546
DOI: 10.1039/C9TA07697B
ISSN: 2050-7488
Publisher: Royal Society of Chemistry
Start Page: 25102
End Page: 25111
Journal / Book Title: Journal of Materials Chemistry A
Volume: 7
Issue: 43
Copyright Statement: © The Royal Society of Chemistry 2019
Sponsor/Funder: Engineering & Physical Science Research Council (EPSRC)
Funder's Grant Number: EP/R002010/1
Keywords: 0303 Macromolecular and Materials Chemistry
Publication Status: Published
Online Publication Date: 2019-10-16
Appears in Collections:Materials
Faculty of Natural Sciences