Chemical and Electrochemical Properties of La0.58Sr0.4Fe0.8Co0.2O3-δ (LSCF) Thin Films upon Oxygen Reduction and Evolution Reactions

Simon Pitscheider, Michael Machala, Zixuan Guan, Di Chen, Johan Hjelm, Torben Jacobsen, William C. Chueh, Mogens Bjerg Mogensen, Christodoulos Chatzichristodoulou

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Abstract

The Oxygen Evolution and Oxygen Reduction Reactions (OER/ORR), occurring at the oxygen electrode of Solid Oxide Cells (SOCs) in the two possible ways of operation, require substantial overpotentials, therefore lowering the operating efficiency of the cells. The reaction mechanisms occurring at these electrodes are still not completely understood due to their complexity and localized character at the interfaces between different materials or between the gas atmosphere and the electrocatalyst, and need in situ techniques with very high chemical sensitivity, with the additional difficulty of probing the materials as close as possible to their realistic operating conditions. In addition, the properties of LSCF are, despite numerous studies, still unclear in many aspects, despite LSCF being one of the state-of-the-art electrocatalysts used for SOCs. It is understood that the surface chemical composition deviates from the nominal bulk composition, and that secondary phases can segregate at the surfaces and interfaces during operation. Furthermore, the electrochemical properties such as Area Specific Resistance (ASR), oxygen exchange coefficient (kex), ASR activation energy (Ea) and pO2exponents for LSCF reported in the literature vary considerably. This study aims to better understand the properties of LSCF, by combining the results of Electrochemical Impedance Spectroscopy (EIS) and Near-Ambient Pressure X-ray Photoelectron Spectroscopy (NAP-XPS) on model electrodes, both in polarized and unpolarized conditions. In particular, NAP-XPS studies of the surface chemistry evolution under operation, as well as the correlation between surface potential changes in relation to the applied overpotential are addressed, in an attempt to determine the real driving force for the oxygen reactions.For this purpose, thin films of LSCF are deposited by Pulsed Laser Deposition (PLD) through shadow masks, in order to obtain well-defined electrode geometries with low risk of contamination, and subsequently tested both in highly clean EIS measuring setups and at the synchrotron beamline. The results of both kinds of experiments are correlated, the goal being a better understanding of the material’s properties under operation, as well as possible degradation phenomena.
Original languageEnglish
Publication date2017
Publication statusPublished - 2017
Event232nd ECS meeting - National Harbor, Washington, DC, United States
Duration: 1 Oct 20175 Oct 2017
http://www.electrochem.org/232

Conference

Conference232nd ECS meeting
CountryUnited States
CityNational Harbor, Washington, DC
Period01/10/201705/10/2017
Internet address

Cite this

@conference{a49d386f21eb41daa5321d9f006626f6,
title = "Chemical and Electrochemical Properties of La0.58Sr0.4Fe0.8Co0.2O3-δ (LSCF) Thin Films upon Oxygen Reduction and Evolution Reactions",
abstract = "The Oxygen Evolution and Oxygen Reduction Reactions (OER/ORR), occurring at the oxygen electrode of Solid Oxide Cells (SOCs) in the two possible ways of operation, require substantial overpotentials, therefore lowering the operating efficiency of the cells. The reaction mechanisms occurring at these electrodes are still not completely understood due to their complexity and localized character at the interfaces between different materials or between the gas atmosphere and the electrocatalyst, and need in situ techniques with very high chemical sensitivity, with the additional difficulty of probing the materials as close as possible to their realistic operating conditions. In addition, the properties of LSCF are, despite numerous studies, still unclear in many aspects, despite LSCF being one of the state-of-the-art electrocatalysts used for SOCs. It is understood that the surface chemical composition deviates from the nominal bulk composition, and that secondary phases can segregate at the surfaces and interfaces during operation. Furthermore, the electrochemical properties such as Area Specific Resistance (ASR), oxygen exchange coefficient (kex), ASR activation energy (Ea) and pO2exponents for LSCF reported in the literature vary considerably. This study aims to better understand the properties of LSCF, by combining the results of Electrochemical Impedance Spectroscopy (EIS) and Near-Ambient Pressure X-ray Photoelectron Spectroscopy (NAP-XPS) on model electrodes, both in polarized and unpolarized conditions. In particular, NAP-XPS studies of the surface chemistry evolution under operation, as well as the correlation between surface potential changes in relation to the applied overpotential are addressed, in an attempt to determine the real driving force for the oxygen reactions.For this purpose, thin films of LSCF are deposited by Pulsed Laser Deposition (PLD) through shadow masks, in order to obtain well-defined electrode geometries with low risk of contamination, and subsequently tested both in highly clean EIS measuring setups and at the synchrotron beamline. The results of both kinds of experiments are correlated, the goal being a better understanding of the material’s properties under operation, as well as possible degradation phenomena.",
author = "Simon Pitscheider and Michael Machala and Zixuan Guan and Di Chen and Johan Hjelm and Torben Jacobsen and Chueh, {William C.} and Mogensen, {Mogens Bjerg} and Christodoulos Chatzichristodoulou",
year = "2017",
language = "English",
note = "232nd ECS meeting ; Conference date: 01-10-2017 Through 05-10-2017",
url = "http://www.electrochem.org/232",

}

Pitscheider, S, Machala, M, Guan, Z, Chen, D, Hjelm, J, Jacobsen, T, Chueh, WC, Mogensen, MB & Chatzichristodoulou, C 2017, 'Chemical and Electrochemical Properties of La0.58Sr0.4Fe0.8Co0.2O3-δ (LSCF) Thin Films upon Oxygen Reduction and Evolution Reactions' 232nd ECS meeting, National Harbor, Washington, DC, United States, 01/10/2017 - 05/10/2017, .

Chemical and Electrochemical Properties of La0.58Sr0.4Fe0.8Co0.2O3-δ (LSCF) Thin Films upon Oxygen Reduction and Evolution Reactions. / Pitscheider, Simon; Machala, Michael; Guan, Zixuan; Chen, Di; Hjelm, Johan; Jacobsen, Torben; Chueh, William C.; Mogensen, Mogens Bjerg; Chatzichristodoulou, Christodoulos.

2017. Abstract from 232nd ECS meeting, National Harbor, Washington, DC, United States.

Research output: Contribution to conferenceConference abstract for conferenceResearchpeer-review

TY - ABST

T1 - Chemical and Electrochemical Properties of La0.58Sr0.4Fe0.8Co0.2O3-δ (LSCF) Thin Films upon Oxygen Reduction and Evolution Reactions

AU - Pitscheider, Simon

AU - Machala, Michael

AU - Guan, Zixuan

AU - Chen, Di

AU - Hjelm, Johan

AU - Jacobsen, Torben

AU - Chueh, William C.

AU - Mogensen, Mogens Bjerg

AU - Chatzichristodoulou, Christodoulos

PY - 2017

Y1 - 2017

N2 - The Oxygen Evolution and Oxygen Reduction Reactions (OER/ORR), occurring at the oxygen electrode of Solid Oxide Cells (SOCs) in the two possible ways of operation, require substantial overpotentials, therefore lowering the operating efficiency of the cells. The reaction mechanisms occurring at these electrodes are still not completely understood due to their complexity and localized character at the interfaces between different materials or between the gas atmosphere and the electrocatalyst, and need in situ techniques with very high chemical sensitivity, with the additional difficulty of probing the materials as close as possible to their realistic operating conditions. In addition, the properties of LSCF are, despite numerous studies, still unclear in many aspects, despite LSCF being one of the state-of-the-art electrocatalysts used for SOCs. It is understood that the surface chemical composition deviates from the nominal bulk composition, and that secondary phases can segregate at the surfaces and interfaces during operation. Furthermore, the electrochemical properties such as Area Specific Resistance (ASR), oxygen exchange coefficient (kex), ASR activation energy (Ea) and pO2exponents for LSCF reported in the literature vary considerably. This study aims to better understand the properties of LSCF, by combining the results of Electrochemical Impedance Spectroscopy (EIS) and Near-Ambient Pressure X-ray Photoelectron Spectroscopy (NAP-XPS) on model electrodes, both in polarized and unpolarized conditions. In particular, NAP-XPS studies of the surface chemistry evolution under operation, as well as the correlation between surface potential changes in relation to the applied overpotential are addressed, in an attempt to determine the real driving force for the oxygen reactions.For this purpose, thin films of LSCF are deposited by Pulsed Laser Deposition (PLD) through shadow masks, in order to obtain well-defined electrode geometries with low risk of contamination, and subsequently tested both in highly clean EIS measuring setups and at the synchrotron beamline. The results of both kinds of experiments are correlated, the goal being a better understanding of the material’s properties under operation, as well as possible degradation phenomena.

AB - The Oxygen Evolution and Oxygen Reduction Reactions (OER/ORR), occurring at the oxygen electrode of Solid Oxide Cells (SOCs) in the two possible ways of operation, require substantial overpotentials, therefore lowering the operating efficiency of the cells. The reaction mechanisms occurring at these electrodes are still not completely understood due to their complexity and localized character at the interfaces between different materials or between the gas atmosphere and the electrocatalyst, and need in situ techniques with very high chemical sensitivity, with the additional difficulty of probing the materials as close as possible to their realistic operating conditions. In addition, the properties of LSCF are, despite numerous studies, still unclear in many aspects, despite LSCF being one of the state-of-the-art electrocatalysts used for SOCs. It is understood that the surface chemical composition deviates from the nominal bulk composition, and that secondary phases can segregate at the surfaces and interfaces during operation. Furthermore, the electrochemical properties such as Area Specific Resistance (ASR), oxygen exchange coefficient (kex), ASR activation energy (Ea) and pO2exponents for LSCF reported in the literature vary considerably. This study aims to better understand the properties of LSCF, by combining the results of Electrochemical Impedance Spectroscopy (EIS) and Near-Ambient Pressure X-ray Photoelectron Spectroscopy (NAP-XPS) on model electrodes, both in polarized and unpolarized conditions. In particular, NAP-XPS studies of the surface chemistry evolution under operation, as well as the correlation between surface potential changes in relation to the applied overpotential are addressed, in an attempt to determine the real driving force for the oxygen reactions.For this purpose, thin films of LSCF are deposited by Pulsed Laser Deposition (PLD) through shadow masks, in order to obtain well-defined electrode geometries with low risk of contamination, and subsequently tested both in highly clean EIS measuring setups and at the synchrotron beamline. The results of both kinds of experiments are correlated, the goal being a better understanding of the material’s properties under operation, as well as possible degradation phenomena.

M3 - Conference abstract for conference

ER -

Pitscheider S, Machala M, Guan Z, Chen D, Hjelm J, Jacobsen T et al. Chemical and Electrochemical Properties of La0.58Sr0.4Fe0.8Co0.2O3-δ (LSCF) Thin Films upon Oxygen Reduction and Evolution Reactions. 2017. Abstract from 232nd ECS meeting, National Harbor, Washington, DC, United States.