A study conducted by Wataru Yoshimune et al. was published in the ADVANCED SCIENCE.​

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As renewable energy becomes more prevalent, the demand for technologies that can store and utilize surplus electricity in the form of hydrogen is increasing. Although proton exchange membrane water electrolyzer (PEMWE) systems can produce hydrogen efficiently, the presence of water vapor in the produced hydrogen and hydrogen crossover through the membrane pose challenges to safe operation. The behavior of water inside the water electrolysis cell plays a significant role in these issues, yet the distribution and movement of liquid water within the porous layer of the hydrogen electrode remain unclear.​

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This study used operando synchrotron X-ray radiography to visualize the distribution and dynamics of liquid water inside the cathode of a PEM water electrolyzer during operation. The results revealed that the behavior of water is primarily governed by current density and temperature. At low temperatures, liquid water moves continuously. At high temperatures, however, evaporation accelerates and causes the movement to shift to a cyclic pattern in which liquid water accumulates and is then expelled. Furthermore, the study demonstrated that the supply of water driven by current density competes with its removal by hydrogen gas. This result can be used to predict the state of the water in the hydrogen electrode under operating conditions that change with the amount of electricity generated. This can help design efficient operating conditions.​

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These findings are expected to deepen our understanding of the mechanisms involved in water vapor ingress and hydrogen crossover. They will also serve as fundamental guidelines for optimizing future material design, cell structures, and operating conditions.​

 

Title: Operando Visualization of Cathode Water Management in Proton Exchange Membrane Water Electrolyzers Using Synchrotron X-Ray Radiography​
Authors: Yoshimune, W., Hayakawa, T., Miyase, Y.​
Journal Name: ADVANCED SCIENCE ​
Published: August 19, 2026​
https://doi.org/10.1002/advs.77246​