Porous transport layers with low Pt loading having Nb–Ta alloy as interlayer for proton exchange membrane water electrolyzers

Abstract

Titanium (Ti), commercially used as substrate for porous transport layers (PTLs) in proton exchange membrane water electrolyzers (PEMWEs), tends to form passivating oxide layer, increasing interfacial contact resistance (ICR) and reducing performance and durability; practice of using precious metal coatings for mitigation significantly increases costs. This study investigates niobium-tantalum (Nb–Ta) alloys as cost-effective interlayer coatings on Ti-felt to reduce precious metal loading. Nb–Ta coated samples significantly increase corrosion potential, lower current densities by 3–4 orders of magnitude, reduce ICR by 3.5 times, and improve durability. The best performance sample with an ultra-low amount of platinum, shows 8 times greater durability, 12.5% reduction in ohmic resistance and 28% increase in current density at +2.0 V than the commercial PTL in a single cell stack. Improved contact angle, electrical, and thermal conductivity highlight Nb–Ta interlayer coatings for PTLs, offering a cost-effective strategy to enhance PEMWE performance and durability for green hydrogen production.