Replication data and analysis scripts for: Insights into the Ir–O redox dynamics of an operating PEM water electrolyzer using in operando Raman spectroscopy

Jülich DATA

Abstract

Replication data and analysis scripts for: Insights into the Ir–O redox dynamics of an operating PEM water electrolyzer using in operando Raman spectroscopy This repository provides the experimental data and analysis scripts supporting a research study on the structural evolution of iridium-based oxygen evolution reaction (OER) catalysts under in operando conditions. The scientific objective of the underlying work is to understand how catalytically active species form and transform during potential-dependent electrolysis and subsequent relaxation at open-circuit potential in application-relevant proton exchange membrane (PEM) systems. In the associated study, in operando Raman spectroscopy was combined with electrochemical measurements on catalyst-coated membrane electrode assemblies (CCM-MEAs). Raman spectra were acquired during defined electrochemical protocols and analyzed using a dedicated spectral deconvolution and fitting workflow designed to ensure stability and physical consistency of the extracted components. This repository contains raw electrochemical and in operando Raman spectroscopy data, analysis scripts, and plotting routines used for the deconvolution, quantitative analysis, and visualization of Raman spectra acquired under different electrochemical perturbation conditions. Repository Structure electrochemical_data/ seq >_ type > id >(_ pot > ).txt ... README.md potential/ potentials.txt README.md spectra_norm/ seq >_ type > id >(_ pot > ).txt ... README.md XRD/ prist_Ir_side_5-130deg2th_5h.xy membrane_ref_Ir_side_5-130deg2th_5h.xy operando_Ir_side_5-130deg2th_5h.xy README.md export.pkl fit_script.py plot.py README.md electrochemical_data Contains preprocessed electrochemical data ( seq >_ type > id >(_ pot > ).txt) exported from Gamry .DTA files. Only the relevant columns required for analysis are retained (e.g. time, potential, current). potential Contains the perturbation sequence used during in operando measurements (used for labeling in the fitting script). potentials.txt Defines the sequence of applied potentials or experimental states. Entries may be numeric values or categorical labels (e.g. OCP1). spectra_norm Contains area-normalized Raman spectra ( seq >_ type > id >(_ pot > ).txt) used as input for peak fitting. Raman spectra correspond to the electrochemical states defined in potentials.txt. Files contain Raman shift (cm⁻¹) in the first column and intensity (arb. u.) in the second column. XRD This folder contains XRD diffractograms of the anode sides of the pristine and operated samples, as well as a diffractogram of the pristine MEAs' membrane as reference. export.pkl Serialized Python object containing all fitting results. It stores fitted peak parameters, raw spectra, individual peak curves, constant background terms, and final fitted spectra for all random seeds. This file enables full reproducibility of all plots without rerunning the fitting. The export.pkl file provided with this repository contains all fitted spectra and peak parameters used for the analysis and figures reported in the publication. fit_script.py Main analysis script performing Raman peak fitting using the lmfit library. The script defines peak models, parameter bounds, random seeds, optimizer settings, and exports all results to export.pkl. plot.py Script for generating publication-ready figures from export.pkl. It reconstructs fitted spectra and peak contributions, assigns alphabetical panel labels, and plots averaged peak amplitudes with standard deviations. README.md files For each folder, detailed experimental procedures and relevant information are provided in its README.md file.

Authors 6

1. Stefan Speer

   Forschungszentrum Jülich

   Affiliation as printed

   (IET-1 Forschungszentrum Jülich GmbH)

2. Sven Jovanovic

   Forschungszentrum Jülich

   Affiliation as printed

   (IET-1 Forschungszentrum Jülich GmbH)

3. Christina Oeß Aachen

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   (IET-1 Forschungszentrum Jülich GmbH, IPC RWTH Aachen University)

4. André Karl

   Forschungszentrum Jülich

   Affiliation as printed

   (IET-1 Forschungszentrum Jülich GmbH)

5. Eva Jodat

   Forschungszentrum Jülich

   Affiliation as printed

   (IET-1 Forschungszentrum Jülich GmbH)

6. Rüdiger‐A. Eichel Aachen Faculty of Mechanical Engineering

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   (IET-1 Forschungszentrum Jülich GmbH, IPC RWTH Aachen University, Faculty of Mechanical Engineering RWTH Aachen University)