Triple‑layer porous transport layers with ultra‑high porosity for enhanced oxygen transport and catalyst utilization in water electrolysis

As the world races toward carbon-neutral hydrogen, proton-exchange-membrane water electrolysis (PEMWE) stands out for its high current density and rapid response. Yet the high cost and performance limits of titanium porous transport layers (PTLs) still block widespread deployment. Now, researchers from KAIST, KIER and Hyundai Motor Company have delivered a comprehensive study on a triple-layer Ti-PTL that shreds voltage loss, boosts catalyst use and is ready for scalable production—offering a clear path to cheaper, greener hydrogen.

Why Triple-Layer PTLs Matter

• Energy Efficiency: 127 mV lower cell voltage at 2 A cm⁻² translates into 8.6 % higher electrical efficiency, directly cutting the energy bill for every kilogram of hydrogen.
• Mass-Transport Gains: a 75 % ultra-porous backing layer plus graded pores vent oxygen faster, slashing mass-transport overpotential at high current densities.
• Manufacturing Ready: tape-casting plus roll-calendering forms meter-scale green tapes in minutes, sidestepping costly, slow powder-sintering routes.

Innovative Design and Features

• Layer Functions: a 25 µm microporous surface smooths contact with the IrO₂ catalyst; a 50 µm interlayer bridges pore-size mismatch; a 185 µm backing layer stores and transports oxygen with minimal pressure drop.
• Digital-Twin Insight: X-ray microscopy reveals 65 % more contact area and 84 % extra triple-phase boundaries versus commercial single-layer PTLs, lifting catalyst utilization without extra noble metal.
• Mechanical Integrity: the interlayer locks fine-pore and coarse-pore regions together, surviving 150 N cm^-2 stack pressure and 50 bar differential pressure without delamination.

Applications and Future Outlook

• Single-Cell Performance: 1.805 V at 2 A cm^-2 and only 15 µV h^-1 decay over 350 h continuous operation—outperforming today’s best sintered PTLs.
• Stack Compatibility: drop-in replacement for existing Ti felts or sintered plates; no new membranes, catalysts or field patterns required.
• Cost Roadmap: material savings and line-speed gains position PEMWE for < 2 V operation at 3 A cm^-2—bringing DOE’s $2 kg^-1 hydrogen target within reach.

This work provides a blueprint for pore-graded, ultra-porous PTLs that unite high performance with low-cost, roll-to-roll fabrication. Expect wider adoption as electrolyzer OEMs scale toward gigawatt green-hydrogen plants—and watch for further advances from the KAIST-led team as they translate lab wins into stack-ready hardware!