Ultrafast synthesis of Ir/RuO₂ with enriched oxygen vacancies for durable acidic water electrolysis

Developing efficient and durable catalysts is crucial for advancing proton exchange membrane water electrolysis (PEMWE) toward sustainable hydrogen production. Ir-based catalysts are stable but limited by scarcity and cost, whereas Ru-based catalysts are more active and affordable yet unstable in acidic media due to Ru over-oxidation into soluble RuO₄ species. Here, we report a heterostructured Ir/RuO₂ catalyst prepared through a combination of an ultrafast high-temperature shock (HTS) process followed by a wet-chemistry deposition of Ir. The HTS method enables the ultrafast synthesis of oxygen vacancy-rich RuO₂ nanoparticles accomplished in 20 s. Subsequently, uniformly dispersed 1.02 nm Ir clusters were anchored on RuO₂, forming a stable Ru-O-Ir interface that enhances catalytic activity and durability. The optimized Ir/RuO₂ via HTS catalysts exhibits an ultra-low overpotential of 150 mV at 10 mA cm⁻² and exceptional stability over 500 h in 0.5 M H₂SO₄ electrolyte. When implemented as anode membrane electrode in proton-exchange membrane water electrolysis (PEMWE), it delivers 1 A cm⁻² at 1.60 V (60 ^◦C) and maintains stable operation for 100 h. In situ characterizations combined with density functional theory (DFT) calculations reveal that oxygen vacancies and strong interfacial charge transfer synergistically facilitate the adsorbate evolution mechanism (AEM) while suppressing Ru dissolution. This work demonstrates a two-step approach for constructing high-utilization-efficiency Ru-Ir catalysts with improved activity and stability for acidic OER.