Interaction between electrode wettability, pressure and bubble dynamics during alkaline water electrolysis

Kerstin Eckert, Helmholtz-Zentrum Dresden-Rossendorf, Germany

Efficient alkaline water electrolysis requires linking material properties and interfacial processes across several scales. Laser-generated microstructures determine wettability and bubble nucleation, while the bubble population controls surface coverage, ohmic resistance and electrode performance. We combine surface characterization, electrochemical measurements, high-speed imaging and interface-resolved simulations of laser-patterned nickel electrodes.
Direct Laser Interference Patterning produces superhydrophilic structures that increase the electrochemically active surface area twelvefold [1]. During oxygen evolution, these electrodes exhibit fewer nucleation sites but larger detached bubbles. Persistent wetting limits bubble-induced blockage and reduces the overpotential by approximately 164 mV at 100 mA cm⁻². Experiments with pillar-patterned electrodes show how structure and wettability interact with pressure during hydrogen evolution [2]. Increasing pressure from 1 to 6 bar reduces bubble size and narrows its distribution. At 25 mA cm⁻², the potential follows the thermodynamic penalty predicted by the Nernst equation. At 100 mA cm⁻², reduced bubble-induced losses outweigh this penalty and improve the potential by up to approximately 60 mV.
Three-dimensional volume-of-fluid simulations resolve interface deformation and the moving three-phase contact line. A dynamic wetting framework incorporates advancing and receding contact angles, contact-angle hysteresis and contact-line dissipation [3]. Static wetting models may predict premature detachment, whereas dynamic wetting captures bubble coalescence, deformation, sliding and detachment. Electrolysis-specific simulations also couple bubble growth and phase change to the primary electric field [4], revealing how non-uniform current density, bubble footprints and interactions on catalytic microelectrode arrays govern surface coverage and ohmic losses.
Together, the experiments and simulations establish a scale-bridging relationship from surface structure and three-dimensional wetting through bubble dynamics to electrode performance.

References:
[1] Rox et al., ACS Appl. Mater. Interfaces 17 (2025) 9364–9377.
[2] Rox et al., arXiv:2603.26855 (2026).
[3] Han, Eckert & Mutschke, Journal of Computational Physics 561 (2026).
[4] Huang, Mutschke, Yuan & Eckert, arXiv:2607.24286 (2026).

Hannes Rox (1, 2), Feng Liang (4), Robert Baumann (3), Xuegeng Yang (1, 2), Andrés F. Lasagni (3), Yifan Han (1, 2), Gerd Mutschke1, Mengyuan Huang (1, 2), and Kerstin Eckert (1, 2)
1 Institute of Fluid Dynamics, Helmholtz-Zentrum Dresden-Rossendorf, 01328 Dresden, Germany
2 Institute of Process Engineering and Environmental Technology, Technische Universität Dresden, 01062 Dresden, Germany.
3 Fraunhofer Institute for Material and Beam Technology IWS, Winterbergstraße 28, 01277 Dresden, Germany.
4 School of Mechanical Engineering, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China