March 27, 2026 Dataset Open Access

Data publication: Bubble-induced versus thermodynamic voltage losses during pressurized alkaline water electrolysis

Rox, Hannes; Liang, Feng; Baumann, Robert; Marzec, Mateusz M.; Sokołowski, Krystian; Yang, Xuegeng; Lasagni, Andrés F.; van de Krol, Roel; Eckert, Kerstin

Understanding how bubbles influence the efficiency of water electrolysis is crucial to achieve economically competitive hydrogen, generated by renewable energy sources, such as wind and solar power. Water electrolysis is typically performed at high pressures to  lower the cost of the energy-intensive mechanical compression required for the produced hydrogen. Thus, a better understanding of how absolute pressure affects electrochemical performance and bubble size is necessary.  This data set compares four laser-structured Ni electrodes with different spatial periods (Λ = 30, 40, 60, and 100 μm) at a constant depth of ≈ 7 μm. The comparison is made in terms of electrode potential, detached bubble size, and the number of nucleation sites. The applied current density was varied between j = -25, -50, and -100 mA/cm², and the absolute cell pressure was varied between p = 1, 2, 4, and 6 bar. The electrolyte used was 1 M KOH. All experiments were carried out at a constant temperature of T = 293 K.

A.) Description of Data.zip:

An overview of all performed experiments is given in the file Summary.csv. The data is analyzed as described in the corresponding journal publication Bubble-induced versus thermodynamic voltage losses during pressurized alkaline water electrolysis. Each data set is stored in a .hdf5-file, with the relevant metadata incorporated into the attributes assigned to the groups/datasets within the .hdf5-file. The data files are structured in groups as follows:

• Electrochemical Measurement Data
  • Galvanostatic Measurement Data
• Results
  • Detected Bubbles Frontview
• Frontview Raw Images (only for LS_P_01.hdf5)

With the exception of a single comprehensive data set comprising unprocessed images (LS_P_01.hdf5), the remaining raw images from all performed measurements can be made available upon request.

B.) Description of Videos.zip:

Example videos of non-structured and laser-structured electrodes at a current density of -100 mA/cm² are provided. The characteristic videos provided are named according to the following scheme:

• SpatialPeriod_Pressure_CurrentDensity
• E.g.: 100μm_6bar_-100mAcm-2