Quantifying Dynamic Changes of Oxygen Nonstoichiometry and Formation of Surface Phases of SrCoOx Electrocatalysts by Operando Characterizations
(2025) In ACS Nano 19(14). p.13999-14009- Abstract
Perovskite electrocatalysts like strontium cobaltite (SrCoOx, denoted as SCO) experience dynamic changes in both surface and bulk during the oxygen evolution reaction (OER), rather than remaining static. This dynamic, electrochemically driven evolution in composition, structure, and ionic defects (e.g., oxygen vacancies) can strongly impact the OER activity and stability. Yet, the current lack of quantitative information on these processes impedes a precise and predictive evaluation of the individual and combined effect of both bulk and surface transformations. Here, using epitaxial SCO thin films as a model system, we demonstrate that SCO is a bulk and surface redox-active OER electrocatalyst that undergoes a bulk phase... (More)
Perovskite electrocatalysts like strontium cobaltite (SrCoOx, denoted as SCO) experience dynamic changes in both surface and bulk during the oxygen evolution reaction (OER), rather than remaining static. This dynamic, electrochemically driven evolution in composition, structure, and ionic defects (e.g., oxygen vacancies) can strongly impact the OER activity and stability. Yet, the current lack of quantitative information on these processes impedes a precise and predictive evaluation of the individual and combined effect of both bulk and surface transformations. Here, using epitaxial SCO thin films as a model system, we demonstrate that SCO is a bulk and surface redox-active OER electrocatalyst that undergoes a bulk phase transition via electrochemically induced oxygen intercalation, as well as a surface phase transition toward Co (oxy-)hydroxide. Specifically, applying a suite of operando and ex situ characterization we established a reliable relationship between oxygen nonstoichiometry, optical density, and conductivity as a function of applied potentials. We further accurately quantify the evolution of oxygen stoichiometry in the SCO bulk and the thickness of the formed surface secondary phase. Our work provides a reliable and generalizable workflow and operando characterization toolbox for quantitative assessment of surface and bulk transformations in oxygen-deficient perovskite electrocatalysts.
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- author
- Hu, Yang ; Wei, Luhan ; Chen, Haowen ; Xu, Zihan ; Shavorskiy, Andrey LU ; Baeumer, Christoph and Lu, Qiyang
- organization
- publishing date
- 2025-04
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- operando characterization, oxygen evolution reaction, perovskite oxides, phase transitions, thin film
- in
- ACS Nano
- volume
- 19
- issue
- 14
- pages
- 11 pages
- publisher
- The American Chemical Society (ACS)
- external identifiers
-
- pmid:40189847
- scopus:105002691835
- ISSN
- 1936-0851
- DOI
- 10.1021/acsnano.4c18105
- language
- English
- LU publication?
- yes
- id
- 8697e358-8a47-4cee-b356-3a75df8561fa
- date added to LUP
- 2025-08-18 14:35:17
- date last changed
- 2025-09-01 15:45:27
@article{8697e358-8a47-4cee-b356-3a75df8561fa,
abstract = {{<p>Perovskite electrocatalysts like strontium cobaltite (SrCoO<sub>x</sub>, denoted as SCO) experience dynamic changes in both surface and bulk during the oxygen evolution reaction (OER), rather than remaining static. This dynamic, electrochemically driven evolution in composition, structure, and ionic defects (e.g., oxygen vacancies) can strongly impact the OER activity and stability. Yet, the current lack of quantitative information on these processes impedes a precise and predictive evaluation of the individual and combined effect of both bulk and surface transformations. Here, using epitaxial SCO thin films as a model system, we demonstrate that SCO is a bulk and surface redox-active OER electrocatalyst that undergoes a bulk phase transition via electrochemically induced oxygen intercalation, as well as a surface phase transition toward Co (oxy-)hydroxide. Specifically, applying a suite of operando and ex situ characterization we established a reliable relationship between oxygen nonstoichiometry, optical density, and conductivity as a function of applied potentials. We further accurately quantify the evolution of oxygen stoichiometry in the SCO bulk and the thickness of the formed surface secondary phase. Our work provides a reliable and generalizable workflow and operando characterization toolbox for quantitative assessment of surface and bulk transformations in oxygen-deficient perovskite electrocatalysts.</p>}},
author = {{Hu, Yang and Wei, Luhan and Chen, Haowen and Xu, Zihan and Shavorskiy, Andrey and Baeumer, Christoph and Lu, Qiyang}},
issn = {{1936-0851}},
keywords = {{operando characterization; oxygen evolution reaction; perovskite oxides; phase transitions; thin film}},
language = {{eng}},
number = {{14}},
pages = {{13999--14009}},
publisher = {{The American Chemical Society (ACS)}},
series = {{ACS Nano}},
title = {{Quantifying Dynamic Changes of Oxygen Nonstoichiometry and Formation of Surface Phases of SrCoO<sub>x</sub> Electrocatalysts by Operando Characterizations}},
url = {{http://dx.doi.org/10.1021/acsnano.4c18105}},
doi = {{10.1021/acsnano.4c18105}},
volume = {{19}},
year = {{2025}},
}