A Mössbauer spectral study of degradation in La0.58Sr0.4Fe0.5Co0.5O3−x after long-term operation in solid oxide electrolysis cells

Abdelfattah Mahmoud; Mahmoud Al Daroukh; Marta Lipinska-Chwalek; Martina Luysberg; Frank Tietz; Raphael P. Hermann

doi:10.1016/j.ssi.2017.10.003

A Mössbauer spectral study of degradation in La_0.58Sr_0.4Fe_0.5Co_0.5O_3−x after long-term operation in solid oxide electrolysis cells

Abdelfattah Mahmoud, Mahmoud Al Daroukh, Marta Lipinska-Chwalek, Martina Luysberg, Frank Tietz, Raphael P. Hermann

Neutron & X-Ray Scattering, & Thermophys

Research output: Contribution to journal › Article › peer-review

23 Scopus citations

Abstract

Degradation processes of oxygen electrodes in solid oxide electrolysis cells (SOECs) were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Mössbauer spectroscopy. La_0.58Sr_0.4Fe_0.5Co_0.5O_3−x (LSCF) anodes (oxygen electrode) were analyzed after different long-term operations durations of 1774, 6100 and 9000 h. The results were compared with a cell in the initial state. Besides the LSCF anode, the SOECs were composed of a Ce_0.8Gd_0.2O_1.9 barrier layer between the anode and electrolyte, yttria-stabilized zirconia (YSZ) as electrolyte and Ni-YSZ as cathode (hydrogen electrode). Mössbauer spectra of the iron-containing anode were acquired in order to determine the alteration of the iron oxidation state and its local environment during operation. Mössbauer spectroscopy yields indirect information about the degradation mechanism, especially in combination with SEM, TEM, and XRD. XRD and TEM revealed the appearance of Co₃O₄ during the SOEC operation and SEM analyses confirmed the formation of SrZrO₃ at the electrode/electrolyte interface. The spectral analysis confirmed the reduction of iron from Fe(IV) to Fe(III) in LSCF after long-term operation. The fraction of Fe(IV) in the electrode decreased with time and 18, 15, 13 and 11% were obtained for 0, 1774, 6100, and 9000 h of operation, respectively.

Original language	English
Pages (from-to)	38-43
Number of pages	6
Journal	Solid State Ionics
Volume	312
DOIs	https://doi.org/10.1016/j.ssi.2017.10.003
State	Published - Dec 1 2017

Funding

A. Mahmoud acknowledges the Forschungzentrum Jülich for an international postdoctoral grant ( 2013 ) and the Walloon Region for a Beware Fellowship Academia 2015-1, RESIBAT no. 1510399 . This work was partially funded within the project HORIZONT by the Federal Ministry of Economics and Technology, Germany (Grant: 03ET2014C ). The responsibility for the contents of this work lies with the authors. Research sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U.S. Department of Energy (data analysis and manuscript edition by RPH). The authors gratefully acknowledge Dr. D. Sebold for SEM investigations.

Keywords

Degradation
Mössbauer spectroscopy
Oxygen electrode
SOEC
Safety

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10.1016/j.ssi.2017.10.003

Cite this

@article{5652da0a565c4302bdd2ebf9687841b3,

title = "A M{\"o}ssbauer spectral study of degradation in La0.58Sr0.4Fe0.5Co0.5O3−x after long-term operation in solid oxide electrolysis cells",

abstract = "Degradation processes of oxygen electrodes in solid oxide electrolysis cells (SOECs) were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and M{\"o}ssbauer spectroscopy. La0.58Sr0.4Fe0.5Co0.5O3−x (LSCF) anodes (oxygen electrode) were analyzed after different long-term operations durations of 1774, 6100 and 9000 h. The results were compared with a cell in the initial state. Besides the LSCF anode, the SOECs were composed of a Ce0.8Gd0.2O1.9 barrier layer between the anode and electrolyte, yttria-stabilized zirconia (YSZ) as electrolyte and Ni-YSZ as cathode (hydrogen electrode). M{\"o}ssbauer spectra of the iron-containing anode were acquired in order to determine the alteration of the iron oxidation state and its local environment during operation. M{\"o}ssbauer spectroscopy yields indirect information about the degradation mechanism, especially in combination with SEM, TEM, and XRD. XRD and TEM revealed the appearance of Co3O4 during the SOEC operation and SEM analyses confirmed the formation of SrZrO3 at the electrode/electrolyte interface. The spectral analysis confirmed the reduction of iron from Fe(IV) to Fe(III) in LSCF after long-term operation. The fraction of Fe(IV) in the electrode decreased with time and 18, 15, 13 and 11% were obtained for 0, 1774, 6100, and 9000 h of operation, respectively.",

keywords = "Degradation, M{\"o}ssbauer spectroscopy, Oxygen electrode, SOEC, Safety",

author = "Abdelfattah Mahmoud and {Al Daroukh}, Mahmoud and Marta Lipinska-Chwalek and Martina Luysberg and Frank Tietz and Hermann, {Raphael P.}",

note = "Publisher Copyright: {\textcopyright} 2017 Elsevier B.V.",

year = "2017",

month = dec,

day = "1",

doi = "10.1016/j.ssi.2017.10.003",

language = "English",

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T1 - A Mössbauer spectral study of degradation in La0.58Sr0.4Fe0.5Co0.5O3−x after long-term operation in solid oxide electrolysis cells

AU - Mahmoud, Abdelfattah

AU - Al Daroukh, Mahmoud

AU - Lipinska-Chwalek, Marta

AU - Luysberg, Martina

AU - Tietz, Frank

AU - Hermann, Raphael P.

PY - 2017/12/1

Y1 - 2017/12/1

N2 - Degradation processes of oxygen electrodes in solid oxide electrolysis cells (SOECs) were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Mössbauer spectroscopy. La0.58Sr0.4Fe0.5Co0.5O3−x (LSCF) anodes (oxygen electrode) were analyzed after different long-term operations durations of 1774, 6100 and 9000 h. The results were compared with a cell in the initial state. Besides the LSCF anode, the SOECs were composed of a Ce0.8Gd0.2O1.9 barrier layer between the anode and electrolyte, yttria-stabilized zirconia (YSZ) as electrolyte and Ni-YSZ as cathode (hydrogen electrode). Mössbauer spectra of the iron-containing anode were acquired in order to determine the alteration of the iron oxidation state and its local environment during operation. Mössbauer spectroscopy yields indirect information about the degradation mechanism, especially in combination with SEM, TEM, and XRD. XRD and TEM revealed the appearance of Co3O4 during the SOEC operation and SEM analyses confirmed the formation of SrZrO3 at the electrode/electrolyte interface. The spectral analysis confirmed the reduction of iron from Fe(IV) to Fe(III) in LSCF after long-term operation. The fraction of Fe(IV) in the electrode decreased with time and 18, 15, 13 and 11% were obtained for 0, 1774, 6100, and 9000 h of operation, respectively.

AB - Degradation processes of oxygen electrodes in solid oxide electrolysis cells (SOECs) were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Mössbauer spectroscopy. La0.58Sr0.4Fe0.5Co0.5O3−x (LSCF) anodes (oxygen electrode) were analyzed after different long-term operations durations of 1774, 6100 and 9000 h. The results were compared with a cell in the initial state. Besides the LSCF anode, the SOECs were composed of a Ce0.8Gd0.2O1.9 barrier layer between the anode and electrolyte, yttria-stabilized zirconia (YSZ) as electrolyte and Ni-YSZ as cathode (hydrogen electrode). Mössbauer spectra of the iron-containing anode were acquired in order to determine the alteration of the iron oxidation state and its local environment during operation. Mössbauer spectroscopy yields indirect information about the degradation mechanism, especially in combination with SEM, TEM, and XRD. XRD and TEM revealed the appearance of Co3O4 during the SOEC operation and SEM analyses confirmed the formation of SrZrO3 at the electrode/electrolyte interface. The spectral analysis confirmed the reduction of iron from Fe(IV) to Fe(III) in LSCF after long-term operation. The fraction of Fe(IV) in the electrode decreased with time and 18, 15, 13 and 11% were obtained for 0, 1774, 6100, and 9000 h of operation, respectively.

KW - Degradation

KW - Mössbauer spectroscopy

KW - Oxygen electrode

KW - SOEC

KW - Safety

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DO - 10.1016/j.ssi.2017.10.003

M3 - Article

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EP - 43

JO - Solid State Ionics

JF - Solid State Ionics

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