High‐performance porous transport layers for proton exchange membrane water electrolyzers

Abstract Hydrogen is a favored alternative to fossil fuels due to the advantages of cleanliness, zero emissions, and high calorific value. Large‐scale green hydrogen production can be achieved using proton exchange membrane water electrolyzers (PEMWEs) with utilization of renewable energy. The porous transport layer (PTL), positioned between the flow fields and catalyst layers (CLs) in PEMWEs, plays a critical role in facilitating water/gas transport, enabling electrical/thermal conduction, and mechanically supporting CLs and membranes. Superior corrosion resistance is essential as PTL operates in acidic media with oxygen saturation and high working potential. This paper covers the development of high‐performance titanium‐based PTLs for PEMWEs. The heat/electrical conduction and mass transport mechanisms of PTLs and how they affect the overall performances are reviewed. By carefully designing and controlling substrate microstructure, protective coating, and surface modification, the performance of PTL can be regulated and optimized. The two‐phase mass transport characteristics can be enhanced by fine‐tuning the microstructure and surface wettability of PTL. The addition of a microporous top‐layer can effectively improve PTL|CL contact and increase the availability of catalytic sites. The anticorrosion coatings, which are crucial for chemical stability and conductivity of the PTL, are compared and analyzed in terms of composition, fabrication, and performance.