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

RWTH Aachen University

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

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.

Original language	English
Journal	Journal of Materials Chemistry A
Early online date	20 Feb 2025
DOIs	https://doi.org/10.1039/d4ta07063a
Publication status	Published - 20 Feb 2025

Data Availability Statement

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

Acknowledgements

Discussions with Clement Nicollet, Julius Dąbrowa, Andreas Falkenstein, and Bernd Huppertz are all gratefully acknowledged.

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
Horizon 2020
Fermi Level Engineering Applied
H2020 Marie Skłodowska-Curie Actions	101031819
Deutsche Forschungsgemeinschaft	463184206, SFB 1548

Access to Document

10.1039/d4ta07063aLicence: CC BY

Cite this

@article{6220b1d93aaa4915b7b010c33b31fbd2,

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.",

author = "Schwenkel, {David M.} and {De Souza}, {Roger A.} and Harrington, {George F.}",

year = "2025",

month = feb,

day = "20",

doi = "10.1039/d4ta07063a",

language = "English",

journal = "Journal of Materials Chemistry A",

issn = "2050-7488",

publisher = "Royal Society of Chemistry",

}

TY - JOUR

T1 - Understanding the role of acidity on the surface exchange reaction in mixed conductors

T2 - what is the effect of surface hydration?

AU - Schwenkel, David M.

AU - De Souza, Roger A.

AU - Harrington, George F.

PY - 2025/2/20

Y1 - 2025/2/20

N2 - 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.

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.

UR - http://www.scopus.com/inward/record.url?scp=85219503534&partnerID=8YFLogxK

U2 - 10.1039/d4ta07063a

DO - 10.1039/d4ta07063a

M3 - Article

SN - 2050-7488

JO - Journal of Materials Chemistry A

JF - Journal of Materials Chemistry A

ER -

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

Abstract

Data Availability Statement

Acknowledgements

Funding

Access to Document

Other files and links

Fingerprint

Cite this