This is the data publication accompanying the published manuscript

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'Correlating Electrode Morphology with Electrochemical Properties in PEM
Water Electrolysis CCMs after Variable Load Cycling'
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K. Froehlich, T. Hilche, O. Camara, C. König, I. Park, S. Speer, J. Liu,
S. Jovanovic, F. Hausen, E. Jodat, A. Karl, R.-A. Eichel,
Electrochimica Acta, DOI: 10.1016/j.electacta.2026.150006

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CONTENTS:
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Replication data for experimental results in the manuscript:
- MEA anode activation and conditioning
- AC-SECM
- Electrochemical Characterization
- SEM
- AFM
- Raman
Details are given in the respective subdirectories.

The data publication contains the electrochemical measurement data (current and potential) recorded during activation of 1 MEA anode (representative data) and conditioning (1 V, 2 V, 3 V static potential hold or dynamic potential change between OCP and 2 V) of 4 MEA anodes (measurements performed in an in-house developed cell on a Bio-Logic M470 workstation with a Bio-Logic SP-300 bipotentiostat); the impedance magnitude data recorded in AC-SECM mapping scans of 4 MEA anodes (2 scan positions each) in pristine, activated and conditioned state (measurements performed in an in-house developed cell on a Bio-Logic M470 workstation with a Bio-Logic SP-300 bipotentiostat); the electrochemical characterization data (CV, PEIS, LSV, double layer capacitance) of 4 conditioned MEA anodes (measurements performed in an in-house developed cell with a Bio-Logic VSP-300 potentiostat); the SEM images (SE, BSE, EDX) recorded of 1 pristine MEA anode and 4 conditioned MEA anodes in several acquisition spots (measurements performed with a Tescan Amber X); the AFM measurement data (topography and contact current) recorded of 1 pristine MEA anode and 4 conditioned MEA anodes at two scanning areas (measurements performed on a Bruker Dimension Icon); the Raman spectroscopy data (normalized and averaged spectra, fitting curves and vibration amplitudes) recorded of 1 pristine MEA anode and 4 conditioned MEA anodes (measurements performed on a WITec/Oxford Instruments Alpha 300R); as included in the main manuscript and supporting information of the publication. Read the _README.txt files contained with this dataset for detailed information.

Abstract:
In operation of a proton exchange membrane (PEM) water electrolyzer, the applied electric field has direct impact on the overall cell performance. Thus, an electrochemical break-in procedure is often performed to activate the membrane electrode assembly (MEA) and optimize the cell performance, while accelerated stress tests allow an investigation of the cell durability and degradation behavior, including the MEA. However, the effect of an applied electric field on the electrochemical and correlated morphological properties of MEA electrodes has not been discussed so far. This work examines this influence on Ir black based anodes in commercial MEAs utilizing a multi-technique approach. Here, we present two in-house developed cells for operating an individual MEA electrode as the working electrode in a three-electrode configuration. The impact of MEA treatment in an oxidative environment under constant potential holds or dynamic potential profiles in 1 M H2SO4 solution was examined in alternating current scanning electrochemical microscopy (AC-SECM) studies and by analyzing the double layer capacitance and electrochemical performance for the oxygen evolution reaction. The results show a clear correlation between the electrochemical response and morphological features from oxidation and agglomeration of catalyst material depending on the applied electric field. The exposure to the electric field reduced the anode surface impedance compared to the initial state. Furthermore, the amount of IrOx in the catalyst layer varied between the experimental protocols, directly impacting the density, porosity, electrical conductivity and electrochemical performance of agglomerated material. (2026-08-06)