High‐Entropy Alloy Nano‐Aggregates Enable Durable and High‐Efficiency Oxygen Reduction Reaction

High‐entropy alloys (HEAs) have emerged as exceptional electrocatalysts due to their unique structural and electronic properties. In this work, we synthesized PtRhPdIrRu HEA nanoaggregates by precisely controlling the zeta potential during synthesis. The resulting catalyst demonstrated superior oxygen reduction reaction (ORR) activity in both acidic and alkaline electrolytes, outperforming commercial Pt/C. Remarkably, the HEA nanoaggregates exhibited outstanding stability, retaining half‐wave potentials ( E 1 / 2 ) of 0.851 V after 13,000 cycles in acidic media and 0.864 V after 30,000 cycles in alkaline media. These results highlight the exceptional electrocatalytic performance and durability of HEA nanoaggregates, making them highly promising candidates for next‐generation ORR catalysts.