Understanding the role of acidity on the surface exchange reaction in mixed conductors: what is the effect of surface hydration?

David M. Schwenkel; Roger A. De Souza; George F. Harrington

doi:10.1039/d4ta07063a

Understanding the role of acidity on the surface exchange reaction in mixed conductors: what is the effect of surface hydration?

David M. Schwenkel, Roger A. De Souza, George F. Harrington

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

6 Citations (SciVal)

Abstract

An increasingly robust body of evidence attests that the kinetics of the oxygen exchange reaction at the surface of mixed ionic-electronic conducting oxides can be modified by infiltrating binary oxides. Furthermore, a clear relationship has been found between the reaction rate and the acidity of the surface binary oxide. Nevertheless, the underlying mechanism is still poorly understood. In this study we investigate the effect of acidic and basic infiltrated species (SiO₂ and CaO) on SrTi_0.65Fe_0.35O_3−δ (STF), a perovskite-structured, technologically relevant MIEC. From these experiments and an analysis of literature data, we demonstrate that a model based on electron-transfer as the rate-determining step and a modified surface electron concentration is quantitatively inconsistent with the data. Consequently, we propose instead that water species, present at trace levels in the conditions of the experiments, play a decisive role in the surface exchange kinetics and their modification through acidic or basic infiltrated species.

Original language	English
Pages (from-to)	8541-8548
Number of pages	8
Journal	Journal of Materials Chemistry A
Volume	13
Issue number	12
Early online date	20 Feb 2025
DOIs	https://doi.org/10.1039/d4ta07063a
Publication status	Published - 20 Feb 2025

Bibliographical note

Publisher Copyright:
© 2025 The Royal Society of Chemistry.

Data Availability Statement

The data supporting this article have been included as part of the ESI.

Acknowledgements

Discussions with Clement Nicollet, Julius Dabrowa, Andreas
Falkenstein, and Bernd Huppertz are all gratefully acknowledged. G. F. H. gratefully acknowledges funding from the
European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement
number [101031819 – OPTICS]. This project has received
funding from the Deutsche Forschungsgemeinschaft (DFG,
German Research Foundation) 463184206 (SFB 1548, FLAIR:
Fermi Level Engineering Applied to Oxide Electroceramics).

Funding

Discussions with Clement Nicollet, Julius D\u0105browa, Andreas Falkenstein, and Bernd Huppertz are all gratefully acknowledged. G. F. H. gratefully acknowledges funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement number [101031819 \u2013 OPTICS]. This project has received funding from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) 463184206 (SFB 1548, FLAIR: Fermi Level Engineering Applied to Oxide Electroceramics).

Funders	Funder number
EU - Horizon 2020
Fermi Level Engineering Applied
H2020 Marie Skłodowska-Curie Actions	101031819
Deutsche Forschungsgemeinschaft (DFG)	463184206, SFB 1548

ASJC Scopus subject areas

General Chemistry
Renewable Energy, Sustainability and the Environment
General Materials Science

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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10.1039/d4ta07063aLicence: CC BY

Cite this

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title = "Understanding the role of acidity on the surface exchange reaction in mixed conductors: what is the effect of surface hydration?",

abstract = "An increasingly robust body of evidence attests that the kinetics of the oxygen exchange reaction at the surface of mixed ionic-electronic conducting oxides can be modified by infiltrating binary oxides. Furthermore, a clear relationship has been found between the reaction rate and the acidity of the surface binary oxide. Nevertheless, the underlying mechanism is still poorly understood. In this study we investigate the effect of acidic and basic infiltrated species (SiO2 and CaO) on SrTi0.65Fe0.35O3−δ (STF), a perovskite-structured, technologically relevant MIEC. From these experiments and an analysis of literature data, we demonstrate that a model based on electron-transfer as the rate-determining step and a modified surface electron concentration is quantitatively inconsistent with the data. Consequently, we propose instead that water species, present at trace levels in the conditions of the experiments, play a decisive role in the surface exchange kinetics and their modification through acidic or basic infiltrated species.",

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AB - An increasingly robust body of evidence attests that the kinetics of the oxygen exchange reaction at the surface of mixed ionic-electronic conducting oxides can be modified by infiltrating binary oxides. Furthermore, a clear relationship has been found between the reaction rate and the acidity of the surface binary oxide. Nevertheless, the underlying mechanism is still poorly understood. In this study we investigate the effect of acidic and basic infiltrated species (SiO2 and CaO) on SrTi0.65Fe0.35O3−δ (STF), a perovskite-structured, technologically relevant MIEC. From these experiments and an analysis of literature data, we demonstrate that a model based on electron-transfer as the rate-determining step and a modified surface electron concentration is quantitatively inconsistent with the data. Consequently, we propose instead that water species, present at trace levels in the conditions of the experiments, play a decisive role in the surface exchange kinetics and their modification through acidic or basic infiltrated species.

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Understanding the role of acidity on the surface exchange reaction in mixed conductors: what is the effect of surface hydration?

Abstract

Bibliographical note

Data Availability Statement

Acknowledgements

Funding

ASJC Scopus subject areas

UN SDGs

Access to Document

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