Detailed understanding of the electrochemistry and oxygen reduction activity of La1–xCaxMnO3 obtained by in situ XAS and XES
Detailed understanding of the electrochemistry and oxygen reduction activity of La1–xCaxMnO3 obtained by in situ XAS and XES
Understanding the interplay between redox behavior and structural stability is crucial for the development of transition metal oxides in electrocatalysis. In this work, we use both X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES) to investigate the electrochemical response of Mn-based perovskite oxides (La1–xCaxMnO3) under oxygen reduction reaction (ORR) conditions. This dual approach enables tracking of changes in both the oxidation state and local coordination environment. Mn Kβ XES data show that oxidation-state changes are reversible, despite a shift in transition potentials across a range of compositions, including CaMnO3. In contrast, Mn K-edge EXAFS analyses reveal that while LaMnO3 retains structural integrity, CaMnO3 undergoes irreversible structural changes at low potentials, associated with the collapse of the perovskite framework. Intermediate compositions show partially reversible structural behavior. This decoupling of redox reversibility and structural instability, a picture only accessible through the use of XAS and XES, provides critical insight into the complex behavior of these materials under operational conditions. Additionally, our analysis shows that Mn(II) formation is only detected in CaMnO3 at potentials more negative than 0.4 V (vs RHE). The ORR onset is associated with Mn(IV) reduction, while peroxide formation correlates with an increased Mn(III)/Mn(IV) ratio, supporting a 2e– + 2e– reduction pathway. This study demonstrates the power of XAS and XES analyses to disentangle electronic and structural dynamics, providing a more complete understanding of activity–stability relationships in perovskite electrocatalysts.
Mn-based perovskite oxides, oxygen reduction reaction, redox−structure relationships, X-ray absorption spectroscopy, X-ray emission spectroscopy
1190–1196
Celorrio, Veronica
7a8ccfa9-5d90-4502-8008-5e1bb15035c5
Huang, Haoliang
132a8eda-b800-4fa7-9583-6b4306f30247
Hayama, Shusaku
dbaecfbe-b0a6-4b21-9030-b2942d42b33c
Fermin, David J.
3bfcec3e-75fc-487b-9367-ea8c805f4c0d
Russell, Andrea E.
b6b7c748-efc1-4d5d-8a7a-8e4b69396169
7 May 2026
Celorrio, Veronica
7a8ccfa9-5d90-4502-8008-5e1bb15035c5
Huang, Haoliang
132a8eda-b800-4fa7-9583-6b4306f30247
Hayama, Shusaku
dbaecfbe-b0a6-4b21-9030-b2942d42b33c
Fermin, David J.
3bfcec3e-75fc-487b-9367-ea8c805f4c0d
Russell, Andrea E.
b6b7c748-efc1-4d5d-8a7a-8e4b69396169
Celorrio, Veronica, Huang, Haoliang, Hayama, Shusaku, Fermin, David J. and Russell, Andrea E.
(2026)
Detailed understanding of the electrochemistry and oxygen reduction activity of La1–xCaxMnO3 obtained by in situ XAS and XES.
ACS Electrochemistry, 2 (5), .
(doi:10.1021/acselectrochem.5c00541).
Abstract
Understanding the interplay between redox behavior and structural stability is crucial for the development of transition metal oxides in electrocatalysis. In this work, we use both X-ray absorption spectroscopy (XAS) and X-ray emission spectroscopy (XES) to investigate the electrochemical response of Mn-based perovskite oxides (La1–xCaxMnO3) under oxygen reduction reaction (ORR) conditions. This dual approach enables tracking of changes in both the oxidation state and local coordination environment. Mn Kβ XES data show that oxidation-state changes are reversible, despite a shift in transition potentials across a range of compositions, including CaMnO3. In contrast, Mn K-edge EXAFS analyses reveal that while LaMnO3 retains structural integrity, CaMnO3 undergoes irreversible structural changes at low potentials, associated with the collapse of the perovskite framework. Intermediate compositions show partially reversible structural behavior. This decoupling of redox reversibility and structural instability, a picture only accessible through the use of XAS and XES, provides critical insight into the complex behavior of these materials under operational conditions. Additionally, our analysis shows that Mn(II) formation is only detected in CaMnO3 at potentials more negative than 0.4 V (vs RHE). The ORR onset is associated with Mn(IV) reduction, while peroxide formation correlates with an increased Mn(III)/Mn(IV) ratio, supporting a 2e– + 2e– reduction pathway. This study demonstrates the power of XAS and XES analyses to disentangle electronic and structural dynamics, providing a more complete understanding of activity–stability relationships in perovskite electrocatalysts.
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detailed-understanding-of-the-electrochemistry-and-oxygen-reduction-activity-of-la1-xcaxmno3-obtained-by-in-situ-xas
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Accepted/In Press date: 26 March 2026
e-pub ahead of print date: 14 April 2026
Published date: 7 May 2026
Keywords:
Mn-based perovskite oxides, oxygen reduction reaction, redox−structure relationships, X-ray absorption spectroscopy, X-ray emission spectroscopy
Identifiers
Local EPrints ID: 512595
URI: http://eprints.soton.ac.uk/id/eprint/512595
PURE UUID: e5242bff-decf-4296-93d2-0b9d1a7dde44
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Date deposited: 09 Jul 2026 16:56
Last modified: 14 Aug 2026 10:02
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Contributors
Author:
Veronica Celorrio
Author:
Haoliang Huang
Author:
Shusaku Hayama
Author:
David J. Fermin
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