Activation of Oxygen Evolution Electrocatalysis via Reduced Ruthenium–Oxygen–Ruthenium Coordination

Noble metal oxides such as RuO2 are the state-of-the-art electrocatalysts for anodic reactions in acidic electrolytes, but their scarcity and moderate activity greatly limit emerging renewable energy technologies. Here, we show that oxidized overlayers of ruthenium on earth-abundant manganese oxide (MnO2/o-RuOx) nanocrystal supports exhibit Ru chemical states associated with reduced Ru-O-Ru coordination that enable dynamic switching of hydrogen bonding, with *OH intermediates hydrogen bonding to surface O and *OOH intermediates bonding to protruding RuOx clusters. The resulting electrocatalysts exhibit an overpotential of 218.9 ± 0.3 mV at 10 mA cm-2 for the oxygen evolution reaction in acid, corresponding to a 2425% increase in Ru mass activity compared to RuO2, enabling the construction of electrolyzers that achieved 3 A cm-2 at 1.646 V, 5.54 A cm-2 at 1.8 V, and exhibited over 3000-h stability at 100 mA cm-2. These findings motivate further efforts to develop nanomaterials that harness reduced Ru-O-Ru coordination to enable emerging renewable energy technologies.