---
_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: '62814'
abstract:
- lang: eng
text: Porous carbons are prominent electrode materials in energy storage applications
such as supercapacitors. However, rational materials development is hampered by
difficulties in interpreting electrochemical impedance spectra (EIS) and drawing
conclusions about promising aspects of device improvement. Here, we characterized
electrodes consisting of activated carbon with polyacrylic acid binder in four
different concentrations of sulfuric acid, using cyclic voltammetry and electrochemical
impedance spectroscopy. Both datasets were evaluated with simple equivalent circuits
and comparatively analyzed. Conductivity of the electrolyte was independently
measured. Cyclic voltammograms (CV) show larger resistance and capacitance at
low scan rates. Resistances obtained from EIS are in good agreement with those
obtained by cyclic voltammograms particularly at high scan rates. The comparison
against specific electrolyte resistance can reveal whether resistances within
the solid electrode architecture or resistances within the electrolyte, partially
confined by pores, are the dominant cause of increased resistance at low scan
rate. Comparison between CV and EIS points to the main electrode capacitance being
described by a constant phase element (CPE) used to fit the low-frequency region
of EIS.
author:
- first_name: Sebastian
full_name: Reinke, Sebastian
id: '117727'
last_name: Reinke
- first_name: Vera
full_name: Khamitsevich, Vera
last_name: Khamitsevich
- first_name: Julia
full_name: Linnemann, Julia
id: '116779'
last_name: Linnemann
orcid: 0000-0001-6883-5424
citation:
ama: 'Reinke S, Khamitsevich V, Linnemann J. Complementary Analysis of Cyclic Voltammograms
and Impedance Spectra of Porous Carbon Electrodes. In: 2024 International Workshop
on Impedance Spectroscopy (IWIS). IEEE; 2025. doi:10.1109/iwis63047.2024.10847115'
apa: Reinke, S., Khamitsevich, V., & Linnemann, J. (2025). Complementary Analysis
of Cyclic Voltammograms and Impedance Spectra of Porous Carbon Electrodes. 2024
International Workshop on Impedance Spectroscopy (IWIS). https://doi.org/10.1109/iwis63047.2024.10847115
bibtex: '@inproceedings{Reinke_Khamitsevich_Linnemann_2025, title={Complementary
Analysis of Cyclic Voltammograms and Impedance Spectra of Porous Carbon Electrodes},
DOI={10.1109/iwis63047.2024.10847115},
booktitle={2024 International Workshop on Impedance Spectroscopy (IWIS)}, publisher={IEEE},
author={Reinke, Sebastian and Khamitsevich, Vera and Linnemann, Julia}, year={2025}
}'
chicago: Reinke, Sebastian, Vera Khamitsevich, and Julia Linnemann. “Complementary
Analysis of Cyclic Voltammograms and Impedance Spectra of Porous Carbon Electrodes.”
In 2024 International Workshop on Impedance Spectroscopy (IWIS). IEEE,
2025. https://doi.org/10.1109/iwis63047.2024.10847115.
ieee: 'S. Reinke, V. Khamitsevich, and J. Linnemann, “Complementary Analysis of
Cyclic Voltammograms and Impedance Spectra of Porous Carbon Electrodes,” 2025,
doi: 10.1109/iwis63047.2024.10847115.'
mla: Reinke, Sebastian, et al. “Complementary Analysis of Cyclic Voltammograms and
Impedance Spectra of Porous Carbon Electrodes.” 2024 International Workshop
on Impedance Spectroscopy (IWIS), IEEE, 2025, doi:10.1109/iwis63047.2024.10847115.
short: 'S. Reinke, V. Khamitsevich, J. Linnemann, in: 2024 International Workshop
on Impedance Spectroscopy (IWIS), IEEE, 2025.'
date_created: 2025-12-03T16:06:09Z
date_updated: 2026-01-19T15:41:43Z
department:
- _id: '985'
doi: 10.1109/iwis63047.2024.10847115
extern: '1'
keyword:
- electrochemical impedance spectroscopy
- distorted cyclic voltammograms
- supercapacitors
- carbon
language:
- iso: eng
publication: 2024 International Workshop on Impedance Spectroscopy (IWIS)
publication_status: published
publisher: IEEE
quality_controlled: '1'
status: public
title: Complementary Analysis of Cyclic Voltammograms and Impedance Spectra of Porous
Carbon Electrodes
type: conference
user_id: '116779'
year: '2025'
...
---
_id: '62812'
abstract:
- lang: eng
text: Attributing features of electrochemical impedance spectra to electrochemical
phenomena is both crucial and frequently ambiguous. To elucidate the origin of
the ohmic part of the spectrum, activated carbon electrodes were prepared with
different contents of polyacrylic acid as binder. Their impedance spectra and
cyclic voltammograms were recorded using sulfuric acid of five different concentrations
as the electrolyte. To distinguish electrolyte resistance and resistances related
to the activated carbon layer of the electrode, the specific electrolyte conductivity
was independently measured and compared against the ohmic part of the electrochemical
impedance spectra (EIS). The capacitive cyclic voltammograms show larger resistive
contributions with higher scan rate and lower electrolyte conductivity. Comparing
the ohmic part of the EIS to the specific resistance of the electrolyte, a linear
function with no statistically significant offset was found. The ohmic part of
the EIS, thus, reflects the electrolyte resistance, not that of the carbon electrode.
author:
- first_name: Sebastian
full_name: Reinke, Sebastian
id: '117727'
last_name: Reinke
- first_name: Vera
full_name: Khamitsevich, Vera
last_name: Khamitsevich
- first_name: Oliver
full_name: Röth, Oliver
id: '117786'
last_name: Röth
- first_name: Julia
full_name: Linnemann, Julia
id: '116779'
last_name: Linnemann
orcid: 0000-0001-6883-5424
citation:
ama: 'Reinke S, Khamitsevich V, Röth O, Linnemann J. Assessment of the Physicochemical
Meaning of the Ohmic Series Resistance Observed for High Frequencies in Electrochemical
Impedance Spectra. In: 2023 International Workshop on Impedance Spectroscopy
(IWIS). IEEE; 2023. doi:10.1109/iwis61214.2023.10302764'
apa: Reinke, S., Khamitsevich, V., Röth, O., & Linnemann, J. (2023). Assessment
of the Physicochemical Meaning of the Ohmic Series Resistance Observed for High
Frequencies in Electrochemical Impedance Spectra. 2023 International Workshop
on Impedance Spectroscopy (IWIS). https://doi.org/10.1109/iwis61214.2023.10302764
bibtex: '@inproceedings{Reinke_Khamitsevich_Röth_Linnemann_2023, title={Assessment
of the Physicochemical Meaning of the Ohmic Series Resistance Observed for High
Frequencies in Electrochemical Impedance Spectra}, DOI={10.1109/iwis61214.2023.10302764},
booktitle={2023 International Workshop on Impedance Spectroscopy (IWIS)}, publisher={IEEE},
author={Reinke, Sebastian and Khamitsevich, Vera and Röth, Oliver and Linnemann,
Julia}, year={2023} }'
chicago: Reinke, Sebastian, Vera Khamitsevich, Oliver Röth, and Julia Linnemann.
“Assessment of the Physicochemical Meaning of the Ohmic Series Resistance Observed
for High Frequencies in Electrochemical Impedance Spectra.” In 2023 International
Workshop on Impedance Spectroscopy (IWIS). IEEE, 2023. https://doi.org/10.1109/iwis61214.2023.10302764.
ieee: 'S. Reinke, V. Khamitsevich, O. Röth, and J. Linnemann, “Assessment of the
Physicochemical Meaning of the Ohmic Series Resistance Observed for High Frequencies
in Electrochemical Impedance Spectra,” 2023, doi: 10.1109/iwis61214.2023.10302764.'
mla: Reinke, Sebastian, et al. “Assessment of the Physicochemical Meaning of the
Ohmic Series Resistance Observed for High Frequencies in Electrochemical Impedance
Spectra.” 2023 International Workshop on Impedance Spectroscopy (IWIS),
IEEE, 2023, doi:10.1109/iwis61214.2023.10302764.
short: 'S. Reinke, V. Khamitsevich, O. Röth, J. Linnemann, in: 2023 International
Workshop on Impedance Spectroscopy (IWIS), IEEE, 2023.'
date_created: 2025-12-03T15:58:28Z
date_updated: 2026-01-19T15:40:41Z
department:
- _id: '985'
doi: 10.1109/iwis61214.2023.10302764
extern: '1'
keyword:
- electrochemical impedance spectroscopy
- supercapacitors
- carbon
language:
- iso: eng
publication: 2023 International Workshop on Impedance Spectroscopy (IWIS)
publication_status: published
publisher: IEEE
quality_controlled: '1'
status: public
title: Assessment of the Physicochemical Meaning of the Ohmic Series Resistance Observed
for High Frequencies in Electrochemical Impedance Spectra
type: conference
user_id: '116779'
year: '2023'
...