Biomimetic Non‐Coplanar Multilayer Defense Architecture Achieves High Current Density Chloride‐Resistant Seawater Oxidation

Rational design of highly active and Cl − ‐tolerant electrocatalysts for the oxygen evolution reaction (OER) is critical to enabling practical seawater electrolysis for hydrogen production. Herein, a novel MCF‐LDH catalyst with a biomimetic ‘Clam‐Shield’ multilevel defense system is synthesized via hydrothermal and in situ redox methods. The innovative z ‐axis non‐coplanar architecture of functional layers enables synergistic chloride resistance via physical blocking (MnO 2 barrier) and electrostatic repulsion (CO 3 2− interlayers). Density functional theory (DFT) calculations elucidate that the MnO 2 modulates the d ‐band center of CoFe‐LDH, while the catalyst exhibits a pronounced thermodynamic preference for OH − adsorption (−1.89 eV) over Cl − (−0.35 eV), thereby stabilizing critical reaction intermediates. Furthermore, the density of states (DOS) analysis of MCF‐LDH reveals enhanced continuity of Fe‐3 d and Co‐3 d orbitals near the Fermi energy ( E f ), indicating improved electronic conductivity. This ‘axial dislocation‐functional synergy’ strategy endows MCF‐LDH with exceptional electrocatalytic performance, delivering low overpotentials of 277 and 304 mV at 300 and 500 mA cm −2 , respectively. Moreover, the MCF‐LDH catalyst presents outstanding long‐term stability, retaining 99.4% and 97.8% of its initial activity after 600 h at high current densities of 500 and 1000 mA cm −2 in alkaline seawater electrolyte. This study provides a promising design strategy for chloride‐resistant OER electrocatalysts.