Confronting Dynamic Operation in Proton Exchange Membrane Water Electrolysis With Hollandite‐Type IrRuO x Anode Nanocatalysts

ABSTRACT The operational instability of IrRu‐based anodes, particularly under the dynamic regimes inherent to renewable energy, remains a critical barrier to cost‐effective proton exchange membrane water electrolysis. Here, we address this challenge by designing hollandite‐structured IrRuO x nanocrystals (H‐IrRuO x ) via a low‐temperature phase‐transition synthesis. Distinct from the conventional rutile structure, the open hollandite framework stabilizes sub‐4‐valent metal sites within a unique coordination environment, which simultaneously enhances the oxygen evolution reaction activity and suppresses metal dissolution by mitigating overoxidation. When integrated into membrane electrode assemblies, the H‐IrRuO x catalyst layer demonstrates exceptional durability, operating stably at industrial current densities (1–2 A cm −2 ) with a minimal voltage decay rate of