Breaking the activity-stability limit in acidic oxygen evolution reaction with dual-iridium active sites.

Meeting terawatt-scale global energy demands requires overcoming the activity-stability trade-off of iridium-based catalysts, the only industrially viable option for acidic water oxidation. Herein, we report a lattice-confinement strategy that creates patches of fully exposed Ir atoms, simultaneously enhancing oxygen evolution reaction (OER) activity and stability in acidic media. In situ vibrational and mass spectroscopy identify peroxo intermediates bridging adjacent Ir atoms, supporting an OER mechanism based on direct O─O radical coupling. Density functional theory reveals synergistic interactions between neighboring Ir atoms that enable O2 evolution through a low-energy pathway. These abundant dual active sites achieve an ultralow overpotential of 198 millivolts at 10 milliamperes per square centimeter and a two-order-of-magnitude higher mass activity than commercial IrO2. Stability calculations further show that lattice confinement suppresses Ir dissolution, enabling durable operation beyond 2 months in acid. This work establishes lattice confinement as an effective route to high-performance catalysts for practical water electrolysis.