Scalable Catalyst Coated Membranes in the Low μg _Ir /cm ² Range for Proton Exchange Membrane Water Electrolysis Facilitated by Antimony-Doped Tin Oxide Nanofibers

Lowering the iridium content in the anodic catalyst layer remains one of the main challenges for proton exchange membrane water electrolysis (PEM-WE), as it can cause discontinuous catalyst layers and increased overpotentials. In this work, we managed to reproducibly cast anodic catalyst layers with a loading as low as 22 μgIr/cm2 by introducing electrospun antimony-doped tin oxide (ATO) nanofibers along the IrOx nanoparticles. In addition to a facilitated fabrication route for low-loaded catalyst layers via casting, electrolyzer cells with these ATO-supported catalyst layers reached a loading-normalized current of 454 A/mgIr at their maximum operating point, which is almost four times higher than the reference cells (120 A/mgIr) with a loading of 100 μgIr/cm2.