Topological Synthesis of 2D High‐Entropy Multimetallic (Oxy)hydroxide for Enhanced Lattice Oxygen Oxidation Mechanism

Abstract Owing to sluggish reaction kinetics and high potential, oxygen evolution reaction (OER) electrocatalysts face a trade‐off between activity and stability. Herein, an innovative topological strategy is presented for preparing 2D multimetallic (oxy)hydroxide, including ternary CoFeZn, quaternary CoFeMnZn, and high‐entropy CoFeMnCuZn. The key to the synthesis lies in using Ca‐rich brownmillerite oxide as a precursor, which possesses inherent structural flexibility enabling tailored elemental adjustments and topologically transforms from a point‐shared structure of metal‐oxygen octahedrons into an edge‐shared structure under alkaline conditions. The presence of Zn in the catalysts causes a shift in the center of the O2p band toward the Fermi level, resulting in more Co⁴⁺ species, which drive holes into oxygen ligands to promote intramolecular oxygen coupling. The triggered lattice oxidation mechanism is identified by detecting peroxo‐like (O₂²⁻) negative species using tetramethylammonium chemical probe, along with ¹⁸O isotope labeling experiments. As a result, the catalyst demonstrates an overpotential of 267 mV at 10 mA cm⁻², ranking it among the top‐performing non‐Ni‐based catalysts. Importantly, the catalysts also show high Fe‐leaching resistance during OER compared to conventional NiFe and CoFe hydroxides/(oxy)hydroxides. The assembled zinc‐air battery enables stable operation for over 225 h at a low charging voltage of 1.93 V.