Current status and future trends in anode porous transport layers for high-efficiency PEM water electrolysis

This review comprehensively analyzes technical fundamentals and engineering solutions for anode porous transport layers (PTLs) in proton exchange membrane water electrolysis (PEMWE). As a critical component governing two-phase transport, conductivity, and mechanical stability, the PTL dictates cell performance at high current densities (>2 A cm −2 ). This work evaluates the operational limits and economics of base materials (titanium, stainless steel, carbon) in the aggressive anodic environment. To resolve capillary bottlenecks and interfacial resistance inherent to conventional stochastic structures, we highlight the paradigm shift toward deterministic architectures, including perforated sheets and monolithic bipolar plate-PTL integration. Furthermore, mitigation strategies for high capital costs and degradation under dynamic renewable loads are addressed via protective coatings, microporous layers, and surface modifications enabling ultra-low iridium loadings. Synthesizing advancements in multiscale modeling and machine learning, this review provides a strategic roadmap for next-generation PTLs to scale green hydrogen infrastructure cost-effectively.