Unlocking the future of green hydrogen: advanced porous transport layers drive high-performance pem water electrolyzers

Proton-exchange-membrane water electrolysis (PEMWE) is widely recognized as a leading technology for producing green hydrogen, offering high efficiency, a compact footprint, and fast dynamic responses. However, as the industry pushes for higher current densities to boost production efficiency, PEMWE performance is increasingly constrained by mass transport and interfacial losses within the cell.

To address this critical bottleneck, researchers from Shanghai Jiao Tong University have published a comprehensive review article in the journal ENGINEERING Energy. The paper systematically analyzes recent advancements in the design, fabrication, and optimization of porous transport layers (PTLs)—the unsung heroes of PEMWE systems.

Positioned directly between the flow field and the catalyst layer, the PTL governs a highly complex two-phase flow: it must efficiently deliver liquid water (H₂O) to the catalytic sites while simultaneously evacuating the generated oxygen (O₂) gas. Additionally, it provides essential electronic conduction, heat dissipation, and mechanical support under harsh, highly acidic, and oxidative anodic conditions. If oxygen bubbles accumulate and block the porous network, water cannot reach the catalyst, leading to severe mass-transport penalties and performance degradation.

The review highlights that optimizing Titanium-based (Ti-based) PTLs through microstructural and surface engineering is the key to unlocking ultra-efficient, high-current-density PEMWE operation.

Key Research Highlights and Advancements:

• Architectural Innovations: Introducing deterministic structures—such as integrated in-plane channels, patterned through-pores, and porosity gradients—helps decouple liquid water supply from oxygen gas removal. This prevents persistent oxygen networks from blocking the catalyst layer, dramatically reducing mass-transport losses.
• Wettability Tuning: Modifying the PTL surface to feature superhydrophilic or amphiphilic properties reshapes capillary forces. This strategic surface chemistry enhances rapid water imbibition and accelerates bubble detachment, effectively mitigating gas saturation without altering the bulk pore network.
• Protective Surface Coatings: Under harsh anodic conditions, unprotected Titanium forms thick passivation layers (TiO₂) that increase electrical resistance. Applying ultra-low-loading noble-metal coatings (such as Ir, Pt, and Au) effectively suppresses this passivation, significantly lowering interfacial contact resistance and enhancing long-term cell durability.
• Microporous Top Layers: Incorporating a microporous layer improves the physical contact between the PTL and the catalyst layer, maximizing catalyst utilization and homogenizing the current distribution to prevent localized "hot spots".
• Advanced Manufacturing Strategies: While precision techniques like laser machining and photolithography offer exceptional design control for mechanistic studies, the review emphasizes the need for scalable manufacturing routes—such as cold-gas spraying and roll-to-roll pressing—to make high-performance PTLs commercially viable.

"Standardized performance evaluation is urgently needed," the authors note, emphasizing that transitioning PTL design from empirical trial-and-error to rational engineering is critical for the commercial deployment of large-scale PEMWE systems.

By providing a clear roadmap for PTL optimization, this review offers vital theoretical and practical guidance for developing the next generation of durable, cost-effective green hydrogen production technologies.

Journal: ENGINEERING Energy

Read the full article for free: https://rdcu.be/frN5h

Cite this article: Xu, T., Ren, Y., Wang, Y. et al. Advances in high-performance porous transport layers for proton-exchange-membrane water electrolyzers: A review. ENGINEERING Energy 20, 10731 (2026). https://doi.org/10.1007/s11708-026-1073-1