Operando Analysis of the Pre-OER Activation of Metal-Doped Co <sub>3</sub> O <sub>4</sub> Nanoparticle Catalysts

Doped Co3O4 nanoparticles are investigated via spectro-electrochemistry in the (pre-) oxygen evolution reaction (OER) regime by tracing the absorption signal of the Co3+ d–d transition under applied bias for getting insight into the catalysts activation and the formation of catalytically active phases. In the low potential regime up to 1.37 VRHE, a rise in the optical absorption signal of the [Co3+]oct d–d transition is observed and attributed to a structural change from [Co2+]tet to [Co3+]oct due to an electrochemically induced surface restructuring with water. For applied potentials higher than 1.37 VRHE an overall offset of the absorption spectra in the UV–vis range, equivalent to a darkening of the materials is detected. This is attributed to the formation of a CoOx(OH)y skin layer as supported by high-energy X-ray diffraction (HE-XRD) measurements. We found that the kinetics of the Co3+ states are heavily influenced by the type of dopant with V-doped Co3O4 exhibiting stable Co3+ states (>20 min) while the Mn-doped Co3O4 Co3+ states reduce within 36 s under reductive bias. We conclude that doping Co3O4 with transition metals affects the formation and potential-dependent thickness of the CoOx(OH)y skin layer as the catalytically active phase and the formation of long-time stable surface Co3+ states after activation in the first OER cycle.

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Publication Details

Journal
ACS Catalysis
Published
2025-10-22
DOI
https://doi.org/10.1021/acscatal.5c03900
Citations
3
Primary Topic
Electrocatalysts for Energy Conversion
Type
article
Field-Weighted Citation Impact
1.09
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article

Operando Analysis of the Pre-OER Activation of Metal-Doped Co 3 O 4 Nanoparticle Catalysts

Stephan Schulz, Julia Linnemann, Leon Jacobse, Arno Bergmann et al.
3 citations
ACS Catalysis
Electrocatalysts for Energy Conversion
1.09
article

Operando Analysis of the Pre-OER Activation of Metal-Doped Co 3 O 4 Nanoparticle Catalysts

Stephan Schulz, Julia Linnemann, Leon Jacobse, Arno Bergmann, Abdulkadir Yaşar, G. Bacher, A. Kotova, Christian Leppin, Laura Kampermann, Beatriz Roldán Cuenya, Julian Klein, Carsten Placke‐Yan, T. Wagner, Samuele Lasagna
article en
3 citations

Abstract

Doped Co3O4 nanoparticles are investigated via spectro-electrochemistry in the (pre-) oxygen evolution reaction (OER) regime by tracing the absorption signal of the Co3+ d–d transition under applied bias for getting insight into the catalysts activation and the formation of catalytically active phases. In the low potential regime up to 1.37 VRHE, a rise in the optical absorption signal of the [Co3+]oct d–d transition is observed and attributed to a structural change from [Co2+]tet to [Co3+]oct due to an electrochemically induced surface restructuring with water. For applied potentials higher than 1.37 VRHE an overall offset of the absorption spectra in the UV–vis range, equivalent to a darkening of the materials is detected. This is attributed to the formation of a CoOx(OH)y skin layer as supported by high-energy X-ray diffraction (HE-XRD) measurements. We found that the kinetics of the Co3+ states are heavily influenced by the type of dopant with V-doped Co3O4 exhibiting stable Co3+ states (>20 min) while the Mn-doped Co3O4 Co3+ states reduce within 36 s under reductive bias. We conclude that doping Co3O4 with transition metals affects the formation and potential-dependent thickness of the CoOx(OH)y skin layer as the catalytically active phase and the formation of long-time stable surface Co3+ states after activation in the first OER cycle.

ACS CatalysisVol. 15(21)
Paderborn University (DE), Fritz Haber Institute of the Max Planck Society (DE), Frumkin Institute of Physical Chemistry and Electrochemistry Russian Academy of Sciences (RU), Forschungsinstitut für Anorganische Werkstoffe -Glas/Keramik (DE), Czech Academy of Sciences, Institute of Inorganic Chemistry (CZ), Institute of Inorganic Chemistry of the Slovak Academy of Sciences (SK), ECSI Fibrotools (United States) (US), Materials and Electrochemical Research (United States) (US), University of Duisburg-Essen (DE), Ruhr University Bochum (DE)
Openalex Percentile: Top 21%
Electrocatalysts for Energy Conversion
1.09
DOISourceOpenAlex
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