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@PHDTHESIS{Gohlke:1024182,
author = {Gohlke, Clara Marie},
othercontributors = {Mechler, Anna Katharina and Etzold, Bastian J. M.},
title = {{E}lectrochemical activation of {N}i-based electrodes for
the alkaline oxygen evolution reaction},
school = {Rheinisch-Westfälische Technische Hochschule Aachen},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2025-11036},
pages = {1 Online-Ressource : Illustrationen},
year = {2025},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University 2026; Dissertation, Rheinisch-Westfälische
Technische Hochschule Aachen, 2025},
abstract = {The transition to renewable energy sources requires
efficient and sustainable energy storage systems, such as
green hydrogen produced by alkaline water electrolysis
(AWE). To meet the rising demands, reducing cell potential
and lowering manufacturing costs are crucial. The sluggish
kinetics of the oxygen evolution reaction at the anode
offers optimization potential by efficient electrocatalyst
design. Here, electrochemical conditioning is a promising
tool as it is easily applicable and versatile. Previously,
electrochemical conditioning has already been used to study
the oxide growth on Ni and Fe and to find a low-cost and
highly active electrocatalyst from steel. However, the
interplay of the conditioning and the Ni:Fe-ratio of the
electrode, which is often stated as oxygen evolution
reaction activity descriptor, is not fully understood yet.
This raises the question of how activation, surface changes,
and electrochemical conditioning parameters are correlated
for a model electrode with a Ni:Fe ratio in the optimum
regime, considering the influence of Fe from the
electrolyte. Investigating this requires a suitable testing
system. While reported analytical electrochemical flow cells
with online downstream analysis (iEFCs) are valuable for
studying activity and stability, their designs differ
significantly from industrial setups, complicating knowledge
transfer.This work addresses these challenges by designing
an iEFC with $\mathrm{1~cm^{2}}$ parallel electrodes to
study the activity and stability of electrocatalysts
simultaneously under industrially more relevant conditions.
Simulation and experimental validation showed that the
herein-designed iEFC enables a precise activity
determination (Koutecký-Levich slope of >0.95) over a wide
potential range and minimal dilution of reaction products
with a restricted volume flow. The stability determination
was proven by online monitoring of the electrode dissolution
with peak smearing comparable to reported values. This
advanced iEFC was used to study the electrochemical
conditioning of Ni-(Fe)-based electrodes to enhance the
oxygen evolution reaction performance. Systematic parameter
variation revealed consistent activation trends across the
tested materials, promising universal activation guidelines
and suggesting a similar activation mechanism. These
activation trends are suggested to result primarily from
surface oxidation and enlargement, with Fe dissolution from
Ni-Fe-based electrodes or rather Fe incorporation into
Ni-based electrodes being linearly linked with the
(hydr)oxide formation. This increased understanding of
conditioning parameters, activation, and surface changes
offers a framework for tailoring any (pre-)catalyst’s
conditioning to maximize performance or induce a certain
surface change. Finally, the enduring activation efficacy
during long-term electrolysis at $\mathrm{100~mA~cm^{-2}}$
and relevance to industrially more relevant conditions was
demonstrated, i.e. $\mathrm{12~cm^{2}}$ electrodes,
application of a separator, 30 wt\% KOH, 80 °C, and higher
loads. This makes the technology, including in-situ
(re)activation of electrodes, more viable for large-scale
applications, helping to reduce cell potential and optimize
the anode manufacturing.Overall, this work stresses the
importance of conditioning in enhancing the OER performance
and demonstrates how to improve the catalysts' effectiveness
by tailoring oxides.},
cin = {422020},
ddc = {620},
cid = {$I:(DE-82)422020_20200514$},
pnm = {BMBF 03HY105A - PrometH2eus : Verbundvorhaben
$H2Giga_QT1.1:$ Projektverbund zur optimierten
Materialentwicklung für die technische H2-Erzeugung durch
verbesserte Sauerstoffelektroden (03HY105A)},
pid = {G:(BMBF)03HY105A},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2025-11036},
url = {https://publications.rwth-aachen.de/record/1024182},
}
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