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Studying Surface Chemistry of Mixed Conducting Perovskite Oxide Electrodes with Synchrotron-Based Soft X-rays

[Image: see text] A fundamental understanding of the electrochemical reactions and surface chemistry at the solid–gas interface in situ and operando is critical for electrode materials applied in electrochemical and catalytic applications. Here, the surface reactions and surface composition of a mod...

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Autores principales: Sha, Zijie, Kerherve, Gwilherm, van Spronsen, Matthijs A., Wilson, George E., Kilner, John A., Held, Georg, Skinner, Stephen J.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Chemical Society 2023
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10591506/
https://www.ncbi.nlm.nih.gov/pubmed/37876977
http://dx.doi.org/10.1021/acs.jpcc.3c04278
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author Sha, Zijie
Kerherve, Gwilherm
van Spronsen, Matthijs A.
Wilson, George E.
Kilner, John A.
Held, Georg
Skinner, Stephen J.
author_facet Sha, Zijie
Kerherve, Gwilherm
van Spronsen, Matthijs A.
Wilson, George E.
Kilner, John A.
Held, Georg
Skinner, Stephen J.
author_sort Sha, Zijie
collection PubMed
description [Image: see text] A fundamental understanding of the electrochemical reactions and surface chemistry at the solid–gas interface in situ and operando is critical for electrode materials applied in electrochemical and catalytic applications. Here, the surface reactions and surface composition of a model of mixed ionic and electronic conducting (MIEC) perovskite oxide, (La(0.8)Sr(0.2))(0.95)Cr(0.5)Fe(0.5)O(3-δ) (LSCrF8255), were investigated in situ using synchrotron-based near-ambient pressure (AP) X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine-structure spectroscopy (NEXAFS). The measurements were conducted with a surface temperature of 500 °C under 1 mbar of dry oxygen and water vapor, to reflect the implementation of the materials for oxygen reduction/evolution and H(2)O electrolysis in the applications such as solid oxide fuel cell (SOFC) and electrolyzers. Our direct experimental results demonstrate that, rather than the transition metal (TM) cations, the surface lattice oxygen is the significant redox active species under both dry oxygen and water vapor environments. It was proven that the electron holes formed in dry oxygen have a strong oxygen character. Meanwhile, a relatively higher concentration of surface oxygen vacancies was observed on the sample measured in water vapor. We further showed that in water vapor, the adsorption and dissociation of H(2)O onto the perovskite surface were through forming hydroxyl groups. In addition, the concentration of Sr surface species was found to increase over time in dry oxygen due to Sr surface segregation, with the presence of oxygen holes on the surface serving as an additional driving force. Comparatively, less Sr contents were observed on the sample in water vapor, which could be due to the volatility of Sr(OH)(2). A secondary phase was also observed, which exhibited an enrichment in B-site cations, particularly in Fe and relatively in Cr, and a deficiency in A-site cation, notably in La and relatively in Sr. The findings and methodology of this study allow for the quantification of surface defect chemistry and surface composition evolution, providing crucial understanding and design guidelines in the electrocatalytic activity and durability of electrodes for efficient conversions of energy and fuels.
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spelling pubmed-105915062023-10-24 Studying Surface Chemistry of Mixed Conducting Perovskite Oxide Electrodes with Synchrotron-Based Soft X-rays Sha, Zijie Kerherve, Gwilherm van Spronsen, Matthijs A. Wilson, George E. Kilner, John A. Held, Georg Skinner, Stephen J. J Phys Chem C Nanomater Interfaces [Image: see text] A fundamental understanding of the electrochemical reactions and surface chemistry at the solid–gas interface in situ and operando is critical for electrode materials applied in electrochemical and catalytic applications. Here, the surface reactions and surface composition of a model of mixed ionic and electronic conducting (MIEC) perovskite oxide, (La(0.8)Sr(0.2))(0.95)Cr(0.5)Fe(0.5)O(3-δ) (LSCrF8255), were investigated in situ using synchrotron-based near-ambient pressure (AP) X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine-structure spectroscopy (NEXAFS). The measurements were conducted with a surface temperature of 500 °C under 1 mbar of dry oxygen and water vapor, to reflect the implementation of the materials for oxygen reduction/evolution and H(2)O electrolysis in the applications such as solid oxide fuel cell (SOFC) and electrolyzers. Our direct experimental results demonstrate that, rather than the transition metal (TM) cations, the surface lattice oxygen is the significant redox active species under both dry oxygen and water vapor environments. It was proven that the electron holes formed in dry oxygen have a strong oxygen character. Meanwhile, a relatively higher concentration of surface oxygen vacancies was observed on the sample measured in water vapor. We further showed that in water vapor, the adsorption and dissociation of H(2)O onto the perovskite surface were through forming hydroxyl groups. In addition, the concentration of Sr surface species was found to increase over time in dry oxygen due to Sr surface segregation, with the presence of oxygen holes on the surface serving as an additional driving force. Comparatively, less Sr contents were observed on the sample in water vapor, which could be due to the volatility of Sr(OH)(2). A secondary phase was also observed, which exhibited an enrichment in B-site cations, particularly in Fe and relatively in Cr, and a deficiency in A-site cation, notably in La and relatively in Sr. The findings and methodology of this study allow for the quantification of surface defect chemistry and surface composition evolution, providing crucial understanding and design guidelines in the electrocatalytic activity and durability of electrodes for efficient conversions of energy and fuels. American Chemical Society 2023-10-09 /pmc/articles/PMC10591506/ /pubmed/37876977 http://dx.doi.org/10.1021/acs.jpcc.3c04278 Text en © 2023 The Authors. Published by American Chemical Society https://creativecommons.org/licenses/by/4.0/Permits the broadest form of re-use including for commercial purposes, provided that author attribution and integrity are maintained (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Sha, Zijie
Kerherve, Gwilherm
van Spronsen, Matthijs A.
Wilson, George E.
Kilner, John A.
Held, Georg
Skinner, Stephen J.
Studying Surface Chemistry of Mixed Conducting Perovskite Oxide Electrodes with Synchrotron-Based Soft X-rays
title Studying Surface Chemistry of Mixed Conducting Perovskite Oxide Electrodes with Synchrotron-Based Soft X-rays
title_full Studying Surface Chemistry of Mixed Conducting Perovskite Oxide Electrodes with Synchrotron-Based Soft X-rays
title_fullStr Studying Surface Chemistry of Mixed Conducting Perovskite Oxide Electrodes with Synchrotron-Based Soft X-rays
title_full_unstemmed Studying Surface Chemistry of Mixed Conducting Perovskite Oxide Electrodes with Synchrotron-Based Soft X-rays
title_short Studying Surface Chemistry of Mixed Conducting Perovskite Oxide Electrodes with Synchrotron-Based Soft X-rays
title_sort studying surface chemistry of mixed conducting perovskite oxide electrodes with synchrotron-based soft x-rays
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10591506/
https://www.ncbi.nlm.nih.gov/pubmed/37876977
http://dx.doi.org/10.1021/acs.jpcc.3c04278
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