Dataset of "Effects of Catalyst Loading and Nafion Content on the Activity and Stability of Ir-Based Thin Catalyst Layers for the Oxygen Evolution Reaction"

Proton-exchange-membrane water electrolysis (PEMWE) is a leading technology for scalable, carbon-free hydrogen production, but its widespread adoption is limited by the cost and scarcity of iridium (Ir) oxygen-evolution catalysts. To develop stable, low-loading anodes, standardized testing procedures must be established based on a clear understanding of how each catalyst-layer component, including the catalyst loading and ionomer binder, affects performance and degradation. Here, we systematically investigate how catalyst loading and Nafion ionomer content affect the activity–stability tradeoff in metallic Ir and thermally prepared IrOx. Real-time Ir dissolution is tracked using scanning flow cell coupled with inductively coupled plasma mass spectrometry (SFC-ICP-MS) and benchmarked with rotating-disk electrode (RDE) measurements, while morphology and interfacial properties are analyzed by SEM-EDX, X-ray photoelectron spectroscopy, and contact-angle goniometry. Varying Ir loading has minimal effect on the activity or dissolution of metallic Ir. By contrast, Nafion–catalyst interactions strongly influence both utilization and degradation: weak binding on metallic Ir leads to poor dispersion, coffee-ring effects, and reduced electrochemically active surface area, while strong binding on IrOx improves dispersion and boosts activity at moderate loadings but increases dissolution, likely due to sulfonate interactions or reduced agglomerate size. Across both catalysts, 10 wt.% Nafion provides the best balance between performance and durability. These results demonstrate the critical role of interfacial chemistry in electrocatalyst design and offer practical guidance for developing low-loading, durable PEMWE anodes for renewable hydrogen production.