Synergistic Ir-Ir Duet Atoms on CoOOH Enable Efficient Water Oxidation

초록

Single-atom catalysts (SACs) have been extensively explored for the oxygen evolution reaction (OER) owing to their maximal atom utilization and high mass activity. However, isolated single-metal centers often suffer from intrinsic linear scaling relationships among oxygenated intermediates, thereby limiting their catalytic efficiency in the complex four-electron OER process. To overcome these limitations, we construct atomically dispersed Ir-Ir duet atoms anchored on CoOOH surface (Ir2/CoOOH) to break the intrinsic scaling relationships governing the OER. Benefiting from the synergistic interaction between adjacent Ir atoms, Ir2/CoOOH exhibits an ultralow overpotential of ∼235 mV at 10 mA cm−2 and outstanding durability over 1200 h at 500 mA cm−2 in 1 M KOH. Remarkably, Ir2/CoOOH achieves a turnover frequency approximately three times higher than that of isolated Ir single atoms on the CoOOH surface (Ir1/CoOOH), highlighting the critical role of synergistic duet cooperation in enhancing intrinsic OER activity. Operando spectroscopic measurements combined with theoretical calculations reveal that cooperative Ir-Ir interactions and strong metal-support interactions optimize the local charge density of Ir active centers, regulate the rate-determining step, and significantly lower the activation free energy of the OER. These findings demonstrate the effectiveness of atomically dispersed duet-metal sites in overcoming activity limitations in water oxidation catalysis.

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