Zehua Dou, Hannes Rox, Zyzi Ramos, Robert Baumann, Rachappa Ravishankar, Peter Czurratis, Xuegeng Yang, Andrés Fabián Lasagni, Kerstin Eckert, Juergen Czarske, David Weik
Improved understanding of gas/liquid transport in electrochemical gas-evolving systems is increasingly demanded for optimizing device performance. However, high-resolution measurement techniques for in-situ imaging remain limited. This work demonstrates the use of volumetric scanning acoustic microscopy (SAM) for quantifying hydrogen bubble distribution in porous nickel electrodes in a customized alkaline water electrolysis cell. By using high-frequency focused ultrasound, SAM enables volumetric imaging with high spatial resolution in the range of tens of micrometers. This allows the distribution of gas bubbles within the complex 3D architecture of porous electrodes to be resolved. Digital image processing methods are used to segment and quantify the gas content in the electrode. Thus, non-destructive SAM imaging is demonstrated to be an accessible and scalable analytical tool for the quantitative investigation of bubble distribution in electrochemical environments. Here, a methodological foundation is established for future studies aimed at optimizing bubble dynamics and cell design under practically relevant operating conditions, ultimately contributing to higher electrolysis efficiencies. • Volumetric SAM imaging quantifies H2 bubbles in porous Ni electrodes. • Demonstrated applicability for both mesh and open cell foam electrode structures. • Provides 10's μm spatial resolution in opaque, technically relevant electrodes. • Non-destructive, scalable technique for gas-evolving electrochemical systems.