Time-resolved oxygen bubble dynamics in proton exchange membrane electrolyser

Oxygen bubble formation at the anode of proton exchange membrane water electrolysers (PEMWEs) strongly influences electrocatalyst utilisation, mass-transport resistance, and cell efficiency. This work reports a new full-frame, millisecond-resolved experimental study of oxygen bubble dynamics on the anode porous transport layer (PTL) using high-speed imaging (2000 fps) and deep-learning segmentation in a transparent PEMWE. Bubble emergence, growth, detachment, and transport are quantified across a 38 mm optical window. Bubble emergence rates are two to three times higher near the outer PTL than at the centre. Transport preferentially follows a stable radial–angular direction aligned with anode-side flow imposed by the circular architecture and inlet–outlet configuration. Spatiotemporal mapping reveals persistent pathways not observable using snapshot-based imaging. These results provide quantitative insight into oxygen bubble transport heterogeneity and support bubble-management strategies for PEM water electrolysers.