---
_id: '63675'
abstract:
- lang: eng
text: Cobalt spinel (Co3O4) catalysts are widely studied in scope of the electrocatalytic
oxygen evolution reaction (OER), yet the role of interfacial structural transformation
under anodic bias remains under debate. Here, we employ an operando approach,
combining a fast electrochemical quartz crystal microbalance with dissipation
monitoring (EQCM-D), electrochemical impedance spectroscopy (EIS), and Raman spectroscopy
to investigate interfacial transformations of Co3O4 nanoparticle electrodes in
alkaline electrolyte. We identify two distinct regimes during the anodic sweep
prior to the macroscopic OER onset. At lower potentials, the catalyst interface
remains mechanically rigid while reversibly associating several OH−/H2O species
per oxidized cobalt site. At higher potentials, pronounced softening of the interface
occurs alongside further uptake of electrolyte species. This indicates amorphization
and a ‘swelling process’ beyond simple adsorption. Notably, an electrochemical
conditioning treatment can suppress mass and compliance hysteresis without affecting
OER activity, suggesting that most incorporated electrolyte species do not participate
in the OER. EIS further reveals that OER intermediates form well below the apparent
OER onset potential. These results advance our mechanistic understanding of interfacial
transformations in cobalt-based OER catalysts and establish EQCM-D as a sensitive
operando technique for probing electrocatalyst transformations.
article_number: e01104
author:
- first_name: Christian
full_name: Leppin, Christian
id: '117722'
last_name: Leppin
- first_name: Carsten
full_name: Placke‐Yan, Carsten
last_name: Placke‐Yan
- first_name: Georg
full_name: Bendt, Georg
last_name: Bendt
- first_name: Sheila
full_name: Hernandez, Sheila
last_name: Hernandez
- first_name: Kristina
full_name: Tschulik, Kristina
last_name: Tschulik
- first_name: Stephan
full_name: Schulz, Stephan
last_name: Schulz
- first_name: Julia
full_name: Linnemann, Julia
id: '116779'
last_name: Linnemann
orcid: 0000-0001-6883-5424
citation:
ama: 'Leppin C, Placke‐Yan C, Bendt G, et al. Interfacial Softening and Electrolyte
Uptake in Co3O4 OER Catalysts: Insight from Operando
Spectroscopy and Fast EQCM‐D. ChemCatChem. 2026;18(2). doi:10.1002/cctc.202501104'
apa: 'Leppin, C., Placke‐Yan, C., Bendt, G., Hernandez, S., Tschulik, K., Schulz,
S., & Linnemann, J. (2026). Interfacial Softening and Electrolyte Uptake in
Co3O4 OER Catalysts: Insight from Operando Spectroscopy
and Fast EQCM‐D. ChemCatChem, 18(2), Article e01104. https://doi.org/10.1002/cctc.202501104'
bibtex: '@article{Leppin_Placke‐Yan_Bendt_Hernandez_Tschulik_Schulz_Linnemann_2026,
title={Interfacial Softening and Electrolyte Uptake in Co3O4
OER Catalysts: Insight from Operando Spectroscopy and Fast EQCM‐D}, volume={18},
DOI={10.1002/cctc.202501104},
number={2e01104}, journal={ChemCatChem}, publisher={Wiley}, author={Leppin, Christian
and Placke‐Yan, Carsten and Bendt, Georg and Hernandez, Sheila and Tschulik, Kristina
and Schulz, Stephan and Linnemann, Julia}, year={2026} }'
chicago: 'Leppin, Christian, Carsten Placke‐Yan, Georg Bendt, Sheila Hernandez,
Kristina Tschulik, Stephan Schulz, and Julia Linnemann. “Interfacial Softening
and Electrolyte Uptake in Co3O4 OER Catalysts: Insight from
Operando Spectroscopy and Fast EQCM‐D.” ChemCatChem 18, no. 2 (2026).
https://doi.org/10.1002/cctc.202501104.'
ieee: 'C. Leppin et al., “Interfacial Softening and Electrolyte Uptake in
Co3O4 OER Catalysts: Insight from Operando Spectroscopy
and Fast EQCM‐D,” ChemCatChem, vol. 18, no. 2, Art. no. e01104, 2026, doi:
10.1002/cctc.202501104.'
mla: 'Leppin, Christian, et al. “Interfacial Softening and Electrolyte Uptake in
Co3O4 OER Catalysts: Insight from Operando Spectroscopy
and Fast EQCM‐D.” ChemCatChem, vol. 18, no. 2, e01104, Wiley, 2026, doi:10.1002/cctc.202501104.'
short: C. Leppin, C. Placke‐Yan, G. Bendt, S. Hernandez, K. Tschulik, S. Schulz,
J. Linnemann, ChemCatChem 18 (2026).
date_created: 2026-01-20T19:33:40Z
date_updated: 2026-01-20T19:36:51Z
department:
- _id: '985'
doi: 10.1002/cctc.202501104
intvolume: ' 18'
issue: '2'
keyword:
- electrocatalysis
- Co3O4
- EQCM-D
- OER
language:
- iso: eng
main_file_link:
- open_access: '1'
oa: '1'
publication: ChemCatChem
publication_identifier:
issn:
- 1867-3880
- 1867-3899
publication_status: published
publisher: Wiley
quality_controlled: '1'
status: public
title: 'Interfacial Softening and Electrolyte Uptake in Co3O4
OER Catalysts: Insight from Operando Spectroscopy and Fast EQCM‐D'
type: journal_article
user_id: '116779'
volume: 18
year: '2026'
...
---
_id: '64182'
abstract:
- lang: eng
text: Overcoming the slow kinetics of the oxygen evolution reaction at the anode
is a key challenge for the production of hydrogen via electrolysis. This reaction
operates at very positive potentials, where the electrocatalyst is exposed to
highly oxidative conditions and prone to potential-dependent transformation of
the near-surface region. While substantial evidence for such surface restructuring
exists, its extent and relevance for the catalyst’s activity are unclear. We address
this topic for the case of Co3O4, one of the best-known electrocatalysts exhibiting
surface restructuring, by studies of epitaxial (111)-ordered electrodeposited
films with combined operando X-ray surface diffraction and absorption spectroscopy,
electrochemical impedance spectroscopy, and electrochemical measurements on rotating
disk electrodes. Comparison of the as-prepared and annealed state of the same
samples, which both are stable even under long-term oxygen evolution conditions,
provides clear insight into the role of surface defects. Our results show that
defect-free annealed Co3O4(111) surfaces are structurally stable over a wide potential
range and hydroxylate via adsorption at surface oxygen and Co sites. Potential-induced
surface restructuring of the Co3O4 lattice occurs only in the presence of surface
defects, leading to the formation of the well-known nanometer-thick oxyhydroxide
skin layer. The presence of this skin layer promotes oxygen evolution at low overpotentials
but results in higher Tafel slopes. As a result, highly ordered Co3O4(111) surfaces
are more active at high current densities than defective Co3O4 surfaces that undergo
surface restructuring. These results highlight that strategies for catalyst surface
defect engineering need to be application-oriented.
article_number: acscatal.5c08785
article_type: original
author:
- first_name: Carl Hendric
full_name: Scharf, Carl Hendric
last_name: Scharf
- first_name: Alex
full_name: Chandraraj, Alex
last_name: Chandraraj
- first_name: Konrad
full_name: Dyk, Konrad
last_name: Dyk
- first_name: Felix
full_name: Stebner, Felix
last_name: Stebner
- first_name: Sören
full_name: Lepin, Sören
last_name: Lepin
- first_name: Jing
full_name: Tian, Jing
last_name: Tian
- first_name: Laila
full_name: El Bergmi Byaz, Laila
last_name: El Bergmi Byaz
- first_name: Jochim
full_name: Stettner, Jochim
last_name: Stettner
- first_name: Christian
full_name: Leppin, Christian
id: '117722'
last_name: Leppin
- first_name: Anastasiia
full_name: Kotova, Anastasiia
last_name: Kotova
- first_name: Sebastian
full_name: Reinke, Sebastian
id: '117727'
last_name: Reinke
- first_name: Julia
full_name: Linnemann, Julia
id: '116779'
last_name: Linnemann
orcid: 0000-0001-6883-5424
- first_name: Fouad
full_name: Maroun, Fouad
last_name: Maroun
- first_name: Olaf M.
full_name: Magnussen, Olaf M.
last_name: Magnussen
citation:
ama: Scharf CH, Chandraraj A, Dyk K, et al. Role of Defects in Reversible Surface
Restructuring and Activity of Co3O4 Oxygen Evolution Electrocatalysts.
ACS Catalysis. Published online 2026. doi:10.1021/acscatal.5c08785
apa: Scharf, C. H., Chandraraj, A., Dyk, K., Stebner, F., Lepin, S., Tian, J., El
Bergmi Byaz, L., Stettner, J., Leppin, C., Kotova, A., Reinke, S., Linnemann,
J., Maroun, F., & Magnussen, O. M. (2026). Role of Defects in Reversible Surface
Restructuring and Activity of Co3O4 Oxygen Evolution Electrocatalysts.
ACS Catalysis, Article acscatal.5c08785. https://doi.org/10.1021/acscatal.5c08785
bibtex: '@article{Scharf_Chandraraj_Dyk_Stebner_Lepin_Tian_El Bergmi Byaz_Stettner_Leppin_Kotova_et
al._2026, title={Role of Defects in Reversible Surface Restructuring and Activity
of Co3O4 Oxygen Evolution Electrocatalysts}, DOI={10.1021/acscatal.5c08785},
number={acscatal.5c08785}, journal={ACS Catalysis}, publisher={American Chemical
Society (ACS)}, author={Scharf, Carl Hendric and Chandraraj, Alex and Dyk, Konrad
and Stebner, Felix and Lepin, Sören and Tian, Jing and El Bergmi Byaz, Laila and
Stettner, Jochim and Leppin, Christian and Kotova, Anastasiia and et al.}, year={2026}
}'
chicago: Scharf, Carl Hendric, Alex Chandraraj, Konrad Dyk, Felix Stebner, Sören
Lepin, Jing Tian, Laila El Bergmi Byaz, et al. “Role of Defects in Reversible
Surface Restructuring and Activity of Co3O4 Oxygen Evolution
Electrocatalysts.” ACS Catalysis, 2026. https://doi.org/10.1021/acscatal.5c08785.
ieee: 'C. H. Scharf et al., “Role of Defects in Reversible Surface Restructuring
and Activity of Co3O4 Oxygen Evolution Electrocatalysts,”
ACS Catalysis, Art. no. acscatal.5c08785, 2026, doi: 10.1021/acscatal.5c08785.'
mla: Scharf, Carl Hendric, et al. “Role of Defects in Reversible Surface Restructuring
and Activity of Co3O4 Oxygen Evolution Electrocatalysts.”
ACS Catalysis, acscatal.5c08785, American Chemical Society (ACS), 2026,
doi:10.1021/acscatal.5c08785.
short: C.H. Scharf, A. Chandraraj, K. Dyk, F. Stebner, S. Lepin, J. Tian, L. El
Bergmi Byaz, J. Stettner, C. Leppin, A. Kotova, S. Reinke, J. Linnemann, F. Maroun,
O.M. Magnussen, ACS Catalysis (2026).
date_created: 2026-02-16T14:22:15Z
date_updated: 2026-02-16T14:25:00Z
department:
- _id: '985'
doi: 10.1021/acscatal.5c08785
keyword:
- electrocatalysis
- oxygen evolution reaction
- cobalt spinel
- operando characterization
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://pubs.acs.org/doi/10.1021/acscatal.5c08785
oa: '1'
publication: ACS Catalysis
publication_identifier:
issn:
- 2155-5435
- 2155-5435
publication_status: published
publisher: American Chemical Society (ACS)
quality_controlled: '1'
status: public
title: Role of Defects in Reversible Surface Restructuring and Activity of Co3O4
Oxygen Evolution Electrocatalysts
type: journal_article
user_id: '116779'
year: '2026'
...
---
_id: '62798'
abstract:
- lang: eng
text: We investigated electrodeposited nanoparticulate nickel selenide (pre)catalysts
that transform into nickel oxides/oxyhydroxides under oxygen evolution reaction
conditions in alkaline solutions. Previous studies of this transformation were
conducted at lower current densities than those of industrial relevance (≥1 A
cm–2). We used ultramicroelectrodes (UMEs) to achieve such current densities,
benefiting from their small size, ensuring low absolute currents and low ohmic
drop but high current densities. Morphological degradation of the catalyst material
was only observed at current densities exceeding 1 A cm–2 but not for smaller
ones. Using X-ray absorption, X-ray photoemission spectroscopy, and X-ray diffraction,
we confirmed that the degradation was accompanied by the literature-known transformation
of nanoparticulate Ni3Se2 (bulk)/NiSe (surface) into nickel oxyhydroxide. The
transformation of the precatalyst goes along with a significant improvement in
the charge transfer kinetics observed by decreasing Tafel slopes with ongoing
experimental time extracted from cyclic voltammetry (CV) experiments and electrochemical
impedance spectroscopy (EIS) in the high-frequency range. However, these kinetic
improvements are accompanied by limitations in mass transport concluded from decreasing
current responses at high overpotentials in CVs and increasing impedance in the
low-frequency range of the EIS spectra after extended CV cycling. These mass transport
limitations originated from morphological degradations at the UME exceeding 1
A cm–2 which we proved by applying identical location scanning electron microscopy.
This has not been reported in studies that have been limited to lower current
densities before. Our findings showcase how UMEs can be used to study (pre)catalysts
(herein nickel selenides) under current densities of industrial relevance in the
absence of ohmic drop-related ambiguities, combined with in-depth materials characterization
studies, e.g., identical location microscopy and advanced spectroscopic methods.
This approach enables direct evaluation and comparison of catalyst materials and
thus demonstrates how to overcome long-standing limitations of electrocatalyst
design and testing.
article_type: original
author:
- first_name: Felix
full_name: Hiege, Felix
last_name: Hiege
- first_name: Chun-Wai
full_name: Chang, Chun-Wai
last_name: Chang
- first_name: Oliver
full_name: Trost, Oliver
last_name: Trost
- first_name: Charlotte E. R.
full_name: van Halteren, Charlotte E. R.
last_name: van Halteren
- first_name: Pouya
full_name: Hosseini, Pouya
last_name: Hosseini
- first_name: Georg
full_name: Bendt, Georg
last_name: Bendt
- first_name: Stephan
full_name: Schulz, Stephan
last_name: Schulz
- first_name: Zhenxing
full_name: Feng, Zhenxing
last_name: Feng
- first_name: Julia
full_name: Linnemann, Julia
id: '116779'
last_name: Linnemann
orcid: 0000-0001-6883-5424
- first_name: Kristina
full_name: Tschulik, Kristina
last_name: Tschulik
citation:
ama: Hiege F, Chang C-W, Trost O, et al. Morphological Degradation of Oxygen Evolution
Reaction-Electrocatalyzing Nickel Selenides at Industrially Relevant Current Densities.
ACS Applied Materials & Interfaces. 2025;17(29):41893-41903. doi:10.1021/acsami.5c05381
apa: Hiege, F., Chang, C.-W., Trost, O., van Halteren, C. E. R., Hosseini, P., Bendt,
G., Schulz, S., Feng, Z., Linnemann, J., & Tschulik, K. (2025). Morphological
Degradation of Oxygen Evolution Reaction-Electrocatalyzing Nickel Selenides at
Industrially Relevant Current Densities. ACS Applied Materials & Interfaces,
17(29), 41893–41903. https://doi.org/10.1021/acsami.5c05381
bibtex: '@article{Hiege_Chang_Trost_van Halteren_Hosseini_Bendt_Schulz_Feng_Linnemann_Tschulik_2025,
title={Morphological Degradation of Oxygen Evolution Reaction-Electrocatalyzing
Nickel Selenides at Industrially Relevant Current Densities}, volume={17}, DOI={10.1021/acsami.5c05381}, number={29},
journal={ACS Applied Materials & Interfaces}, publisher={American Chemical
Society (ACS)}, author={Hiege, Felix and Chang, Chun-Wai and Trost, Oliver and
van Halteren, Charlotte E. R. and Hosseini, Pouya and Bendt, Georg and Schulz,
Stephan and Feng, Zhenxing and Linnemann, Julia and Tschulik, Kristina}, year={2025},
pages={41893–41903} }'
chicago: 'Hiege, Felix, Chun-Wai Chang, Oliver Trost, Charlotte E. R. van Halteren,
Pouya Hosseini, Georg Bendt, Stephan Schulz, Zhenxing Feng, Julia Linnemann, and
Kristina Tschulik. “Morphological Degradation of Oxygen Evolution Reaction-Electrocatalyzing
Nickel Selenides at Industrially Relevant Current Densities.” ACS Applied Materials
& Interfaces 17, no. 29 (2025): 41893–903. https://doi.org/10.1021/acsami.5c05381.'
ieee: 'F. Hiege et al., “Morphological Degradation of Oxygen Evolution Reaction-Electrocatalyzing
Nickel Selenides at Industrially Relevant Current Densities,” ACS Applied Materials
& Interfaces, vol. 17, no. 29, pp. 41893–41903, 2025, doi: 10.1021/acsami.5c05381.'
mla: Hiege, Felix, et al. “Morphological Degradation of Oxygen Evolution Reaction-Electrocatalyzing
Nickel Selenides at Industrially Relevant Current Densities.” ACS Applied Materials
& Interfaces, vol. 17, no. 29, American Chemical Society (ACS), 2025,
pp. 41893–903, doi:10.1021/acsami.5c05381.
short: F. Hiege, C.-W. Chang, O. Trost, C.E.R. van Halteren, P. Hosseini, G. Bendt,
S. Schulz, Z. Feng, J. Linnemann, K. Tschulik, ACS Applied Materials & Interfaces
17 (2025) 41893–41903.
date_created: 2025-12-03T15:08:47Z
date_updated: 2025-12-03T16:27:30Z
department:
- _id: '985'
doi: 10.1021/acsami.5c05381
extern: '1'
intvolume: ' 17'
issue: '29'
keyword:
- Electrocatalysis
- oxygen evolution reaction
- nickel selenide
- microelectrode
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://pubs.acs.org/doi/full/10.1021/acsami.5c05381
oa: '1'
page: 41893-41903
publication: ACS Applied Materials & Interfaces
publication_identifier:
issn:
- 1944-8244
- 1944-8252
publication_status: published
publisher: American Chemical Society (ACS)
quality_controlled: '1'
status: public
title: Morphological Degradation of Oxygen Evolution Reaction-Electrocatalyzing Nickel
Selenides at Industrially Relevant Current Densities
type: journal_article
user_id: '116779'
volume: 17
year: '2025'
...
---
_id: '61982'
abstract:
- lang: eng
text: 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.
article_type: original
author:
- first_name: L.
full_name: Kampermann, L.
last_name: Kampermann
- first_name: J.
full_name: Klein, J.
last_name: Klein
- first_name: T.
full_name: Wagner, T.
last_name: Wagner
- first_name: A.
full_name: Kotova, A.
last_name: Kotova
- first_name: C.
full_name: Placke-Yan, C.
last_name: Placke-Yan
- first_name: A.
full_name: Yasar, A.
last_name: Yasar
- first_name: L.
full_name: Jacobse, L.
last_name: Jacobse
- first_name: S.
full_name: Lasagna, S.
last_name: Lasagna
- first_name: Christian
full_name: Leppin, Christian
id: '117722'
last_name: Leppin
- first_name: S.
full_name: Schulz, S.
last_name: Schulz
- first_name: Julia
full_name: Linnemann, Julia
id: '116779'
last_name: Linnemann
orcid: 0000-0001-6883-5424
- first_name: A.
full_name: Bergmann, A.
last_name: Bergmann
- first_name: B.
full_name: Roldan Cuenya, B.
last_name: Roldan Cuenya
- first_name: G.
full_name: Bacher, G.
last_name: Bacher
citation:
ama: Kampermann L, Klein J, Wagner T, et al. Operando Analysis of the Pre-OER Activation
of Metal-Doped Co3O4 Nanoparticle Catalysts. ACS Catalysis.
2025;15(21):18391-18403. doi:10.1021/acscatal.5c03900
apa: Kampermann, L., Klein, J., Wagner, T., Kotova, A., Placke-Yan, C., Yasar, A.,
Jacobse, L., Lasagna, S., Leppin, C., Schulz, S., Linnemann, J., Bergmann, A.,
Roldan Cuenya, B., & Bacher, G. (2025). Operando Analysis of the Pre-OER Activation
of Metal-Doped Co3O4 Nanoparticle Catalysts. ACS Catalysis,
15(21), 18391–18403. https://doi.org/10.1021/acscatal.5c03900
bibtex: '@article{Kampermann_Klein_Wagner_Kotova_Placke-Yan_Yasar_Jacobse_Lasagna_Leppin_Schulz_et
al._2025, title={Operando Analysis of the Pre-OER Activation of Metal-Doped Co3O4
Nanoparticle Catalysts}, volume={15}, DOI={10.1021/acscatal.5c03900},
number={21}, journal={ACS Catalysis}, publisher={American Chemical Society (ACS)},
author={Kampermann, L. and Klein, J. and Wagner, T. and Kotova, A. and Placke-Yan,
C. and Yasar, A. and Jacobse, L. and Lasagna, S. and Leppin, Christian and Schulz,
S. and et al.}, year={2025}, pages={18391–18403} }'
chicago: 'Kampermann, L., J. Klein, T. Wagner, A. Kotova, C. Placke-Yan, A. Yasar,
L. Jacobse, et al. “Operando Analysis of the Pre-OER Activation of Metal-Doped
Co3O4 Nanoparticle Catalysts.” ACS Catalysis 15,
no. 21 (2025): 18391–403. https://doi.org/10.1021/acscatal.5c03900.'
ieee: 'L. Kampermann et al., “Operando Analysis of the Pre-OER Activation
of Metal-Doped Co3O4 Nanoparticle Catalysts,” ACS Catalysis,
vol. 15, no. 21, pp. 18391–18403, 2025, doi: 10.1021/acscatal.5c03900.'
mla: Kampermann, L., et al. “Operando Analysis of the Pre-OER Activation of Metal-Doped
Co3O4 Nanoparticle Catalysts.” ACS Catalysis, vol.
15, no. 21, American Chemical Society (ACS), 2025, pp. 18391–403, doi:10.1021/acscatal.5c03900.
short: L. Kampermann, J. Klein, T. Wagner, A. Kotova, C. Placke-Yan, A. Yasar, L.
Jacobse, S. Lasagna, C. Leppin, S. Schulz, J. Linnemann, A. Bergmann, B. Roldan
Cuenya, G. Bacher, ACS Catalysis 15 (2025) 18391–18403.
date_created: 2025-10-24T07:49:21Z
date_updated: 2025-12-07T17:15:53Z
department:
- _id: '985'
doi: 10.1021/acscatal.5c03900
intvolume: ' 15'
issue: '21'
keyword:
- electrocatalysis
- oxygen evolution reaction
- cobalt spinel
- operando characterization
- spectroelectrochemistry
language:
- iso: eng
page: 18391-18403
publication: ACS Catalysis
publication_identifier:
issn:
- 2155-5435
- 2155-5435
publication_status: published
publisher: American Chemical Society (ACS)
quality_controlled: '1'
status: public
title: Operando Analysis of the Pre-OER Activation of Metal-Doped Co3O4
Nanoparticle Catalysts
type: journal_article
user_id: '116779'
volume: 15
year: '2025'
...
---
_id: '62810'
abstract:
- lang: eng
text: Cobalt iron containing layered double hydroxides (LDHs) and spinels are promising
catalysts for the electrochemical oxygen evolution reaction (OER). Towards development
of better performing catalysts, the precise tuning of mesostructural features
such as pore size is desirable, but often hard to achieve. Herein, a computer‐controlled
microemulsion‐assisted co‐precipitation (MACP) method at constant pH is established
and compared to conventional co‐precipitation. With MACP, the particle growth
is limited and through variation of the constant pH during synthesis the pore
size of the as‐prepared catalysts is controlled, generating materials for the
systematic investigation of confinement effects during OER. At a threshold pore
size, overpotential increased significantly. Electrochemical impedance spectroscopy
(EIS) indicated a change in OER mechanism, involving the oxygen release step.
It is assumed that in smaller pores the critical radius for gas bubble formation
is not met and therefore a smaller charge‐transfer resistance is observed for
medium frequencies.
article_number: e202202015
article_type: original
author:
- first_name: Anna
full_name: Rabe, Anna
last_name: Rabe
- first_name: Maximilian
full_name: Jaugstetter, Maximilian
last_name: Jaugstetter
- first_name: Felix
full_name: Hiege, Felix
last_name: Hiege
- first_name: Nicolas
full_name: Cosanne, Nicolas
last_name: Cosanne
- first_name: Klaus Friedel
full_name: Ortega, Klaus Friedel
last_name: Ortega
- first_name: Julia
full_name: Linnemann, Julia
id: '116779'
last_name: Linnemann
orcid: 0000-0001-6883-5424
- first_name: Kristina
full_name: Tschulik, Kristina
last_name: Tschulik
- first_name: Malte
full_name: Behrens, Malte
last_name: Behrens
citation:
ama: Rabe A, Jaugstetter M, Hiege F, et al. Tailoring Pore Size and Catalytic Activity
in Cobalt Iron Layered Double Hydroxides and Spinels by Microemulsion‐Assisted
pH‐Controlled Co‐Precipitation. ChemSusChem. 2023;16(10). doi:10.1002/cssc.202202015
apa: Rabe, A., Jaugstetter, M., Hiege, F., Cosanne, N., Ortega, K. F., Linnemann,
J., Tschulik, K., & Behrens, M. (2023). Tailoring Pore Size and Catalytic
Activity in Cobalt Iron Layered Double Hydroxides and Spinels by Microemulsion‐Assisted
pH‐Controlled Co‐Precipitation. ChemSusChem, 16(10), Article e202202015.
https://doi.org/10.1002/cssc.202202015
bibtex: '@article{Rabe_Jaugstetter_Hiege_Cosanne_Ortega_Linnemann_Tschulik_Behrens_2023,
title={Tailoring Pore Size and Catalytic Activity in Cobalt Iron Layered Double
Hydroxides and Spinels by Microemulsion‐Assisted pH‐Controlled Co‐Precipitation},
volume={16}, DOI={10.1002/cssc.202202015},
number={10e202202015}, journal={ChemSusChem}, publisher={Wiley}, author={Rabe,
Anna and Jaugstetter, Maximilian and Hiege, Felix and Cosanne, Nicolas and Ortega,
Klaus Friedel and Linnemann, Julia and Tschulik, Kristina and Behrens, Malte},
year={2023} }'
chicago: Rabe, Anna, Maximilian Jaugstetter, Felix Hiege, Nicolas Cosanne, Klaus
Friedel Ortega, Julia Linnemann, Kristina Tschulik, and Malte Behrens. “Tailoring
Pore Size and Catalytic Activity in Cobalt Iron Layered Double Hydroxides and
Spinels by Microemulsion‐Assisted PH‐Controlled Co‐Precipitation.” ChemSusChem
16, no. 10 (2023). https://doi.org/10.1002/cssc.202202015.
ieee: 'A. Rabe et al., “Tailoring Pore Size and Catalytic Activity in Cobalt
Iron Layered Double Hydroxides and Spinels by Microemulsion‐Assisted pH‐Controlled
Co‐Precipitation,” ChemSusChem, vol. 16, no. 10, Art. no. e202202015, 2023,
doi: 10.1002/cssc.202202015.'
mla: Rabe, Anna, et al. “Tailoring Pore Size and Catalytic Activity in Cobalt Iron
Layered Double Hydroxides and Spinels by Microemulsion‐Assisted PH‐Controlled
Co‐Precipitation.” ChemSusChem, vol. 16, no. 10, e202202015, Wiley, 2023,
doi:10.1002/cssc.202202015.
short: A. Rabe, M. Jaugstetter, F. Hiege, N. Cosanne, K.F. Ortega, J. Linnemann,
K. Tschulik, M. Behrens, ChemSusChem 16 (2023).
date_created: 2025-12-03T15:51:54Z
date_updated: 2025-12-03T16:28:26Z
department:
- _id: '985'
doi: 10.1002/cssc.202202015
extern: '1'
intvolume: ' 16'
issue: '10'
keyword:
- electrocatalysis
- oxygen evolution reaction
- cobalt spinel
- cobalt hydroxide
- LDH
language:
- iso: eng
main_file_link:
- open_access: '1'
oa: '1'
publication: ChemSusChem
publication_identifier:
issn:
- 1864-5631
- 1864-564X
publication_status: published
publisher: Wiley
quality_controlled: '1'
status: public
title: Tailoring Pore Size and Catalytic Activity in Cobalt Iron Layered Double Hydroxides
and Spinels by Microemulsion‐Assisted pH‐Controlled Co‐Precipitation
type: journal_article
user_id: '116779'
volume: 16
year: '2023'
...
---
_id: '62801'
abstract:
- lang: eng
text: The three-dimensional (3D) distribution of individual atoms on the surface
of catalyst nanoparticles plays a vital role in their activity and stability.
Optimising the performance of electrocatalysts requires atomic-scale information,
but it is difficult to obtain. Here, we use atom probe tomography to elucidate
the 3D structure of 10 nm sized Co2FeO4 and CoFe2O4 nanoparticles during oxygen
evolution reaction (OER). We reveal nanoscale spinodal decomposition in pristine
Co2FeO4. The interfaces of Co-rich and Fe-rich nanodomains of Co2FeO4 become trapping
sites for hydroxyl groups, contributing to a higher OER activity compared to that
of CoFe2O4. However, the activity of Co2FeO4 drops considerably due to concurrent
irreversible transformation towards CoIVO2 and pronounced Fe dissolution. In contrast,
there is negligible elemental redistribution for CoFe2O4 after OER, except for
surface structural transformation towards (FeIII, CoIII)2O3. Overall, our study
provides a unique 3D compositional distribution of mixed Co-Fe spinel oxides,
which gives atomic-scale insights into active sites and the deactivation of electrocatalysts
during OER.
article_number: '179'
article_type: original
author:
- first_name: Weikai
full_name: Xiang, Weikai
last_name: Xiang
- first_name: Nating
full_name: Yang, Nating
last_name: Yang
- first_name: Xiaopeng
full_name: Li, Xiaopeng
last_name: Li
- first_name: Julia
full_name: Linnemann, Julia
id: '116779'
last_name: Linnemann
orcid: 0000-0001-6883-5424
- first_name: Ulrich
full_name: Hagemann, Ulrich
last_name: Hagemann
- first_name: Olaf
full_name: Ruediger, Olaf
last_name: Ruediger
- first_name: Markus
full_name: Heidelmann, Markus
last_name: Heidelmann
- first_name: Tobias
full_name: Falk, Tobias
last_name: Falk
- first_name: Matteo
full_name: Aramini, Matteo
last_name: Aramini
- first_name: Serena
full_name: DeBeer, Serena
last_name: DeBeer
- first_name: Martin
full_name: Muhler, Martin
last_name: Muhler
- first_name: Kristina
full_name: Tschulik, Kristina
last_name: Tschulik
- first_name: Tong
full_name: Li, Tong
last_name: Li
citation:
ama: Xiang W, Yang N, Li X, et al. 3D atomic-scale imaging of mixed Co-Fe spinel
oxide nanoparticles during oxygen evolution reaction. Nature Communications.
2022;13(1). doi:10.1038/s41467-021-27788-2
apa: Xiang, W., Yang, N., Li, X., Linnemann, J., Hagemann, U., Ruediger, O., Heidelmann,
M., Falk, T., Aramini, M., DeBeer, S., Muhler, M., Tschulik, K., & Li, T.
(2022). 3D atomic-scale imaging of mixed Co-Fe spinel oxide nanoparticles during
oxygen evolution reaction. Nature Communications, 13(1), Article
179. https://doi.org/10.1038/s41467-021-27788-2
bibtex: '@article{Xiang_Yang_Li_Linnemann_Hagemann_Ruediger_Heidelmann_Falk_Aramini_DeBeer_et
al._2022, title={3D atomic-scale imaging of mixed Co-Fe spinel oxide nanoparticles
during oxygen evolution reaction}, volume={13}, DOI={10.1038/s41467-021-27788-2},
number={1179}, journal={Nature Communications}, publisher={Springer Science and
Business Media LLC}, author={Xiang, Weikai and Yang, Nating and Li, Xiaopeng and
Linnemann, Julia and Hagemann, Ulrich and Ruediger, Olaf and Heidelmann, Markus
and Falk, Tobias and Aramini, Matteo and DeBeer, Serena and et al.}, year={2022}
}'
chicago: Xiang, Weikai, Nating Yang, Xiaopeng Li, Julia Linnemann, Ulrich Hagemann,
Olaf Ruediger, Markus Heidelmann, et al. “3D Atomic-Scale Imaging of Mixed Co-Fe
Spinel Oxide Nanoparticles during Oxygen Evolution Reaction.” Nature Communications
13, no. 1 (2022). https://doi.org/10.1038/s41467-021-27788-2.
ieee: 'W. Xiang et al., “3D atomic-scale imaging of mixed Co-Fe spinel oxide
nanoparticles during oxygen evolution reaction,” Nature Communications,
vol. 13, no. 1, Art. no. 179, 2022, doi: 10.1038/s41467-021-27788-2.'
mla: Xiang, Weikai, et al. “3D Atomic-Scale Imaging of Mixed Co-Fe Spinel Oxide
Nanoparticles during Oxygen Evolution Reaction.” Nature Communications,
vol. 13, no. 1, 179, Springer Science and Business Media LLC, 2022, doi:10.1038/s41467-021-27788-2.
short: W. Xiang, N. Yang, X. Li, J. Linnemann, U. Hagemann, O. Ruediger, M. Heidelmann,
T. Falk, M. Aramini, S. DeBeer, M. Muhler, K. Tschulik, T. Li, Nature Communications
13 (2022).
date_created: 2025-12-03T15:22:16Z
date_updated: 2025-12-03T16:30:12Z
department:
- _id: '985'
doi: 10.1038/s41467-021-27788-2
extern: '1'
intvolume: ' 13'
issue: '1'
keyword:
- electrocatalysis
- oxygen evolution reaction
- cobalt spinel
- electrochemical impedance spectroscopy
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://www.nature.com/articles/s41467-021-27788-2
oa: '1'
publication: Nature Communications
publication_identifier:
issn:
- 2041-1723
publication_status: published
publisher: Springer Science and Business Media LLC
quality_controlled: '1'
status: public
title: 3D atomic-scale imaging of mixed Co-Fe spinel oxide nanoparticles during oxygen
evolution reaction
type: journal_article
user_id: '116779'
volume: 13
year: '2022'
...
---
_id: '62803'
abstract:
- lang: eng
text: The aim to produce highly active, selective, and long-lived electrocatalysts
by design drives major research efforts toward gaining fundamental understanding
of the relationship between material properties and their catalytic performance.
Surface characterization tools enable to assess atomic scale information on the
complexity of electrocatalyst materials. Advancing electrochemical methodologies
to adequately characterize such systems was less of a research focus point. In
this Review, we shed light on the ability to gain fundamental insights into electrocatalysis
from a complementary perspective and establish corresponding design strategies.
These may rely on adopting the perceptions and models of other subareas of electrochemistry,
such as corrosion, battery research, or electrodeposition. Concepts on how to
account for and improve mass transport, manage gas bubble release, or exploit
magnetic fields are highlighted in this respect. Particular attention is paid
to deriving design strategies for nanoelectrocatalysts, which is often impeded,
as structural and physical material properties are buried in electrochemical data
of whole electrodes or even devices. Thus, a second major approach focuses on
overcoming this difference in the considered level of complexity by methods of
single-entity electrochemistry. The gained understanding of intrinsic catalyst
performance may allow to rationally advance design concepts with increased complexity,
such as three-dimensional electrode architectures. Many materials undergo structural
changes upon formation of the working catalyst. Accordingly, developing “precatalysts”
with low hindrance of the electrochemical transformation to the active catalyst
is suggested as a final design strategy.
article_type: review
author:
- first_name: Julia
full_name: Linnemann, Julia
id: '116779'
last_name: Linnemann
orcid: 0000-0001-6883-5424
- first_name: Kannasoot
full_name: Kanokkanchana, Kannasoot
last_name: Kanokkanchana
- first_name: Kristina
full_name: Tschulik, Kristina
last_name: Tschulik
citation:
ama: Linnemann J, Kanokkanchana K, Tschulik K. Design Strategies for Electrocatalysts
from an Electrochemist’s Perspective. ACS Catalysis. 2021;11(9):5318-5346.
doi:10.1021/acscatal.0c04118
apa: Linnemann, J., Kanokkanchana, K., & Tschulik, K. (2021). Design Strategies
for Electrocatalysts from an Electrochemist’s Perspective. ACS Catalysis,
11(9), 5318–5346. https://doi.org/10.1021/acscatal.0c04118
bibtex: '@article{Linnemann_Kanokkanchana_Tschulik_2021, title={Design Strategies
for Electrocatalysts from an Electrochemist’s Perspective}, volume={11}, DOI={10.1021/acscatal.0c04118},
number={9}, journal={ACS Catalysis}, publisher={American Chemical Society (ACS)},
author={Linnemann, Julia and Kanokkanchana, Kannasoot and Tschulik, Kristina},
year={2021}, pages={5318–5346} }'
chicago: 'Linnemann, Julia, Kannasoot Kanokkanchana, and Kristina Tschulik. “Design
Strategies for Electrocatalysts from an Electrochemist’s Perspective.” ACS
Catalysis 11, no. 9 (2021): 5318–46. https://doi.org/10.1021/acscatal.0c04118.'
ieee: 'J. Linnemann, K. Kanokkanchana, and K. Tschulik, “Design Strategies for Electrocatalysts
from an Electrochemist’s Perspective,” ACS Catalysis, vol. 11, no. 9, pp.
5318–5346, 2021, doi: 10.1021/acscatal.0c04118.'
mla: Linnemann, Julia, et al. “Design Strategies for Electrocatalysts from an Electrochemist’s
Perspective.” ACS Catalysis, vol. 11, no. 9, American Chemical Society
(ACS), 2021, pp. 5318–46, doi:10.1021/acscatal.0c04118.
short: J. Linnemann, K. Kanokkanchana, K. Tschulik, ACS Catalysis 11 (2021) 5318–5346.
date_created: 2025-12-03T15:31:28Z
date_updated: 2025-12-03T16:32:18Z
department:
- _id: '985'
doi: 10.1021/acscatal.0c04118
extern: '1'
intvolume: ' 11'
issue: '9'
keyword:
- electrocatalysis
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://pubs.acs.org/doi/full/10.1021/acscatal.0c04118
oa: '1'
page: 5318-5346
publication: ACS Catalysis
publication_identifier:
issn:
- 2155-5435
- 2155-5435
publication_status: published
publisher: American Chemical Society (ACS)
quality_controlled: '1'
status: public
title: Design Strategies for Electrocatalysts from an Electrochemist’s Perspective
type: journal_article
user_id: '116779'
volume: 11
year: '2021'
...
---
_id: '62805'
abstract:
- lang: eng
text: Single-entity electrochemistry allows for assessing electrocatalytic activities
of individual material entities such as nanoparticles (NPs). Thus, it becomes
possible to consider intrinsic electrochemical properties of nanocatalysts when
researching how activity relates to physical and structural material properties.
Conversely, conventional electrochemical techniques provide a normalized sum current
referring to a huge ensemble of NPs constituting, along with additives (e.g.,
binders), a complete catalyst-coated electrode. Accordingly, recording electrocatalytic
responses of single NPs avoids interferences of ensemble effects and reduces the
complexity of electrocatalytic processes, thus enabling detailed description and
modelling. Herein, we present insights into the oxygen evolution catalysis at
individual cubic Co3O4 NPs impacting microelectrodes of different support materials.
Simulating diffusion at supported nanocubes, measured step current signals can
be analyzed, providing edge lengths, corresponding size distributions, and interference-free
turnover frequencies. The provided nano-impact investigation of (electro-)catalyst-support
effects contradicts assumptions on a low number of highly active sites.
article_number: '13137'
article_type: original
author:
- first_name: Zhibin
full_name: Liu, Zhibin
last_name: Liu
- first_name: Manuel
full_name: Corva, Manuel
last_name: Corva
- first_name: Hatem M. A.
full_name: Amin, Hatem M. A.
last_name: Amin
- first_name: Niclas
full_name: Blanc, Niclas
last_name: Blanc
- first_name: Julia
full_name: Linnemann, Julia
id: '116779'
last_name: Linnemann
orcid: 0000-0001-6883-5424
- first_name: Kristina
full_name: Tschulik, Kristina
last_name: Tschulik
citation:
ama: 'Liu Z, Corva M, Amin HMA, Blanc N, Linnemann J, Tschulik K. Single Co3O4
Nanocubes Electrocatalyzing the Oxygen Evolution Reaction: Nano-Impact Insights
into Intrinsic Activity and Support Effects. International Journal of Molecular
Sciences. 2021;22(23). doi:10.3390/ijms222313137'
apa: 'Liu, Z., Corva, M., Amin, H. M. A., Blanc, N., Linnemann, J., & Tschulik,
K. (2021). Single Co3O4 Nanocubes Electrocatalyzing the
Oxygen Evolution Reaction: Nano-Impact Insights into Intrinsic Activity and Support
Effects. International Journal of Molecular Sciences, 22(23), Article
13137. https://doi.org/10.3390/ijms222313137'
bibtex: '@article{Liu_Corva_Amin_Blanc_Linnemann_Tschulik_2021, title={Single Co3O4
Nanocubes Electrocatalyzing the Oxygen Evolution Reaction: Nano-Impact Insights
into Intrinsic Activity and Support Effects}, volume={22}, DOI={10.3390/ijms222313137},
number={2313137}, journal={International Journal of Molecular Sciences}, publisher={MDPI
AG}, author={Liu, Zhibin and Corva, Manuel and Amin, Hatem M. A. and Blanc, Niclas
and Linnemann, Julia and Tschulik, Kristina}, year={2021} }'
chicago: 'Liu, Zhibin, Manuel Corva, Hatem M. A. Amin, Niclas Blanc, Julia Linnemann,
and Kristina Tschulik. “Single Co3O4 Nanocubes Electrocatalyzing
the Oxygen Evolution Reaction: Nano-Impact Insights into Intrinsic Activity and
Support Effects.” International Journal of Molecular Sciences 22, no. 23
(2021). https://doi.org/10.3390/ijms222313137.'
ieee: 'Z. Liu, M. Corva, H. M. A. Amin, N. Blanc, J. Linnemann, and K. Tschulik,
“Single Co3O4 Nanocubes Electrocatalyzing the Oxygen Evolution
Reaction: Nano-Impact Insights into Intrinsic Activity and Support Effects,” International
Journal of Molecular Sciences, vol. 22, no. 23, Art. no. 13137, 2021, doi:
10.3390/ijms222313137.'
mla: 'Liu, Zhibin, et al. “Single Co3O4 Nanocubes Electrocatalyzing
the Oxygen Evolution Reaction: Nano-Impact Insights into Intrinsic Activity and
Support Effects.” International Journal of Molecular Sciences, vol. 22,
no. 23, 13137, MDPI AG, 2021, doi:10.3390/ijms222313137.'
short: Z. Liu, M. Corva, H.M.A. Amin, N. Blanc, J. Linnemann, K. Tschulik, International
Journal of Molecular Sciences 22 (2021).
date_created: 2025-12-03T15:35:52Z
date_updated: 2025-12-03T16:52:35Z
department:
- _id: '985'
doi: 10.3390/ijms222313137
extern: '1'
intvolume: ' 22'
issue: '23'
keyword:
- electrocatalysis
- oxygen evolution reaction
- cobalt spinel
- single-entity electrochemistry
language:
- iso: eng
main_file_link:
- open_access: '1'
oa: '1'
publication: International Journal of Molecular Sciences
publication_identifier:
issn:
- 1422-0067
publication_status: published
publisher: MDPI AG
quality_controlled: '1'
status: public
title: 'Single Co3O4 Nanocubes Electrocatalyzing the Oxygen
Evolution Reaction: Nano-Impact Insights into Intrinsic Activity and Support Effects'
type: journal_article
user_id: '116779'
volume: 22
year: '2021'
...