Effect of Nb interlayer thickness on the performance of porous transport layers for proton exchange membrane water electrolyzers

Polymer electrolyte membrane water electrolyzer (PEMWE) integrated with renewable energy sources is a crucial technology for energy transition. However, the high cost of precious metal-coated porous transport layers (PTLs) is one of the limiting factors for the widespread use of PEMWE. Multi-layered coatings with cost-effective Nb as an interlayer and thin layer of precious metal (one-fourth of commercial) as a top layer could serve as a potential alternative to commercial PTL in PEMWE. This study explored the impact of different thicknesses of Nb interlayer (150, 200, 350 nm) on the electrochemical behavior of multi-layered NbPt coatings, by comparing them with two single layered Pt-coated PTLs (in-house Pt-coated PTL and commercial Pt-coated PTL) under PEMWE simulated condition. The result showed that the Ti PTLs with Nb as an interlayer (150, 200, 350 nm) performed better than the single layered in-house Pt-coated PTL. The best performing multi-layered NbPt (Nb=350 nm, Pt=50 nm) sample was finally compared with commercial Pt (200 nm) coated PTL in the in-situ condition of PEMWE. The multi-layered NbPt coating showed an equivalent performance (1.967 V@3.0 A cm −2 ) compared to commercial Pt coating (1.958 V@3.0 A cm −2 ), making Nb as a promising cost-effective interlayer for PTL coating.