Scanning Acoustic Microscopy for Quantifying Bubble Evolution in Alkaline Water Electrolyzers

TL;DR

This paper demonstrates the use of volumetric scanning acoustic microscopy (SAM) to non-destructively image and quantify hydrogen bubble evolution within porous electrodes during alkaline water electrolysis, providing high-resolution 3D insights.

Contribution

It introduces a novel application of high-frequency SAM for in-situ, volumetric imaging of gas bubbles in electrochemical systems, enabling detailed analysis of bubble dynamics.

Findings

SAM provides high-resolution 3D imaging of bubbles in electrodes

Digital image processing quantifies gas content accurately

The technique is scalable and suitable for operando studies

Abstract

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 evolution 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 evolution in operando electrochemical environments. Here, a solid 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.