Optimized tantalum interlayer thickness for PTLs: Enhancing PEMWE performance, stability, and reducing precious metal loading
Leila Moradizadeh, Mohammadhossein Johar, Yasin Mehdizadeh Chellehbari, Xianguo Li, Samaneh Shahgaldi
Abstract
Proton exchange membrane water electrolyzers (PEMWEs) are clean for green hydrogen production. However, their widespread adoption is hindered by high production costs and durability challenges. The low-rate, high-overpotential oxygen evolution reaction (OER) in the anode requires a robust electrode composed of a porous transport layer (PTL) and an active catalyst. Titanium (Ti)-based PTLs are widely used in PEMWEs due to their excellent corrosion resistance. However, the formation of a non-conductive Ti oxide layer increases interfacial contact resistance (ICR) and degrades performance. While precious metal coatings can address this issue, their high cost limits large-scale application. This study investigates the influence of tantalum (Ta) interlayer thickness on PTL performance to reduce precious metal loading while maintaining conductivity. Polarization curves reveal that a 320 nm Ta interlayer with 50 nm platinum achieves 33 % higher current density at 2.0 V compared to a commercial PTL with 200 nm platinum, requiring four times less precious metal. In-situ durability tests at 2.0 V and 80 °C demonstrate stable current density without degradation. Surface morphology and ICR characterization confirm the electrochemical integrity of the PTLs. These findings highlight that optimized Ta interlayers offer a cost-effective solution for improving the efficiency and stability of PEMWEs.