Unveiling Bubble Dynamics of Proton Exchange Membrane Water Electrolysis at Elevated Temperatures

ABSTRACT Operation of water electrolysers at elevated temperatures (> 100°C) is a promising method for substantially increasing the efficiency and reduce the cost of green hydrogen production. These efficiency gains are thought to be limited by bubble‐related losses, which manifest as ohmic and mass transport overpotentials. However, there is limited experimental evidence of electrolyzer bubble dynamics in these harsh operating conditions. In this work, we conduct a parametric study of a proton exchange membrane electrolyzer's performance at temperatures up to 120°C and pressures up to 100 bar, while obtaining images of bubble growth and transport. We show that, at elevated temperatures, there is a reduction in the average fraction of flow channel area occupied by bubbles as well as bubble‐related losses, which may be attributed to the decrease in water surface tension as described by classical bubble detachment models. These results underscore the advantages of operating at elevated temperatures, which allows higher‐efficiency green hydrogen production.