Highly Stable and Efficient Oxygen Evolution Electrocatalyst Based on Co Oxides Decorated with Ultrafine Ru Nanoclusters

Abstract Exploring highly active and durable electrocatalysts for oxygen evolution reaction (OER) is significant to achieve efficient anion exchange membrane (AEM) water electrolysis. Herein, hollow Co‐based N‐doped porous carbon spheres decorated with ultrafine Ru nanoclusters (HS‐RuCo/NC) are reported as efficient OER electrocatalysts via the pyrolysis of carboxylate‐terminated polystyrene‐templated bimetallic zeolite imidazolate frameworks accommodating Ru (III) ions. The unique hollow structure with hierarchically porous characteristics contributes to the electrolyte penetration for fast mass transport and the exposure of more metal sites. Theoretical and experimental studies reveal the synergistic effect between the in situ formed RuO₂ and Co₃O₄ as another critical factor for the high OER performance, where the coupling of RuO₂ with Co₃O₄ can optimize the electronic configuration of RuO₂/Co₃O₄ heterostructure and decrease the energy barrier during OER. Meanwhile, the presence of Co₃O₄ can efficiently suppress the over‐oxidation of RuO₂, endowing the catalysts with high stability. As expected, when the resultant HS‐RuCo/NC was integrated into an AEM water electrolyzer, the obtained electrolyzer exhibits a cell voltage of 2.07 V to launch the current density of 1 A cm⁻² and excellent long‐term stability at 500 mA cm⁻² under room temperature in alkaline solution, outperforming the commercial RuO₂‐based AEM water electrolyzer (2.19 V).