Combining materials development with structural design: Insights into porous transport layer for proton exchange membrane water electrolysis

The porous transport layer (PTL) as a multifunction part, is a critical component of proton exchange membrane electrolysis cells (PEMECs) and plays a pivotal role in the commercialization of proton exchange membrane water electrolysis (PEMWE). Over the past few decades, researchers have proposed a series of optimization strategies for PTLs aimed at reducing costs and enhancing their performance. This review consolidated the pertinent literature on this topic. First, the mechanisms of overpotential loss inside the PEMEC and the factors of the losses were elucidated to underscore the importance of PTLs in PEMEC performance. Additionally, the technical methodologies commonly used to investigate PTLs were discussed. They provide a foundation for subsequent experimental studies. The review then summarized recent optimization efforts by researchers in terms of material and structure and assessed the impacts of these improvements. Finally, potential future directions for the development of PTLs were proposed, which offer valuable insights for ongoing research and development in this field.