Abstract
Green hydrogen, produced via water electrolysis using renewableelectricity, will play a crucial role in decarbonizing industrial and heavy-dutytransportation sectors. Anion exchange membrane water electrolyzers(AEMWEs) can overcome many of the performance and cost limitationsof incumbent technologies, however, still suffer from durability challengesdue to oxidative instability of anion-exchange ionomers. Herein, the use of anelectro-active porous transport layer as anode (PTL-electrode) is demonstratedto enable efficient and durable AEMWEs. The stainless-steel PTL-electrodesare shown to have superior performance and durability compared to traditionalcatalyst layers containing ionomer and nanoparticle catalysts. An AEMWEcell operating at 2 A cm−2 for over 600 h exhibited a degradation rate ofjust 5 μV h−1 . During operation, the surface composition of the stainless steeltransforms into a mixture of iron and nickel oxyhydroxides, contributing toenhanced oxygen-evolution reaction activity. The combination of experimentalwork and modeling elucidates how the bulk structure of the PTL-electrode offersan additional design dimension to further improve electrolyzer performance.Lastly, a surface modification strategy is applied to a PTL-electrode to achieve aneven higher performing AEMWE (2.3 vs 2.0 A cm−2 at 1.8 V). Overall, this worklays out pathways toward more efficient, durable, and affordable AEMWEs.