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 coup...
