Turning Disorder Into Advantage: Precisely Tailored Hybrid Phase Interfaces in B‐Doped High‐Entropy (FeCoNiCrMn) 3 O 4 for Lattice Oxygen‐Mediated Seawater Electrolysis

ABSTRACT Conventional high‐entropy oxide (HEO) catalysts typically rely on high crystallinity for entropy stabilization, yet their ordered structures often limit the exposure of active sites and compromise the intrinsic activity of HEO. Here, we overturn this paradigm by deliberately introducing controlled structural disorder into two‐dimensional HEO nanosheets. Through boron doping, a crystalline‐amorphous hybrid interface in (FeCoNiCrMn) 3 O 4 is successfully constructed. In this unique structure, the amorphous regions provide abundant defective sites, whereas the preserved crystalline domains ensure efficient charge transport. This intentionally engineered disorder not only enhances the density of the active site but also promotes a shift in the oxygen evolution pathway toward the lattice‐oxygen‐mediated mechanism, thereby significantly reducing the kinetic barrier. The optimized catalyst achieves a low overpotential of only 346 mV to deliver a current density of 200 mA cm −2 and maintains excellent long‐term stability even in chloride‐containing electrolytes. Our work demonstrates that controlled disordering—as opposed to perfect ordering—can simultaneously boost both the catalytic activity and durability of HEOs. This insight offers a feasible and innovative design principle for developing advanced high‐entropy electrocatalysts toward practical applications such as seawater splitting.