A Novel Biomimetic Catalyst with Mn_4‐xNi_xCaO₅ Structure for Superior Oxygen Evolution Reaction

AbstractIn natural plants, Mn4CaO5 cluster with metal‐oxo “distorted chair”‐like structure exhibits excellent oxygen evolution activity. However, the performance of biomimetic oxygen evolution catalysts based on the Mn4CaO5‐like structure is far inferior to expectations. Herein, Ca and Ni are first doped together into birnessite and constructed a “distorted chair”‐like structure unit Mn4‐xNixCaO5 in a birnessite‐like Ca‐Mn(Ni)‐O catalyst, the biomimetic Mn4‐xNixCaO5 unit efficiently activates lattice oxygen and boosts the O─O coupling in oxygen evolution reaction (OER), which allows the catalyst to perform superior OER activity with an outstanding overpotential of 184 mV at 300 mA cm−2. Besides, the birnessite‐like Ca‐Mn(Ni)‐O catalyst is stabilized by coupling to NiMnO3 nanoplate, thus forming a stable catalyst that can work for >500 h without attenuation. This work optimizes biomimetic structures by introducing new elements, which provides new insight into developing efficient biomimetic materials.