Confronting Dynamic Operation in Proton Exchange Membrane Water Electrolysis With Hollandite‐Type IrRuO <i> _x </i> Anode Nanocatalysts

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 <4 µV h^-1 over 3700 h. Crucially, under harsh dynamic cycling, it retains 96% of its initial activity after 36 000 cycles, outperforming conventional benchmarks. This structural engineering strategy provides a viable path to durable, cost-effective hydrogen production under realistic conditions.