High‐Valence Metal Modulating Lattice Oxygen in High‐Entropy Layered Double Hydroxides for Enhanced Oxygen Evolution Reaction

Abstract The oxygen evolution reaction (OER) is hindered by sluggish kinetics due to its complex four‐electron, proton‐coupled mechanism. While noble metal oxides like IrO ₂ and RuO ₂ are effective OER catalysts, their high cost and unsatisfactory stability limit large‐scale applications. High‐entropy layered double hydroxides (HE‐LDHs) offer a promising alternative by enabling multi‐metallic site tuning and entropy‐driven phase stabilization. Herein, VCoNiCuZn and MoCoNiCuZn HE‐LDHs respectively modulated by high‐valence V ⁴⁺ /V ⁵⁺ and Mo ⁶⁺ are hydrothermally synthesized on Ni foam. The MoCoNiCuZn HE‐LDH achieved an overpotential of 186 mV at 10 mA cm ⁻² , which is significantly lower than that of 306 mV obtained from CoNiCuZn LDH. The strong M‐O covalency induced by high‐valence metals facilitates charge redistribution and d ‐ p orbital overlap, activating lattice oxygen and promoting the lattice oxygen mechanism (LOM). The resulting OER performance surpasses most reported multi‐principal element materials and rivals noble‐metal‐doped LDHs. Moreover, high‐entropy stabilization presents excellent structural durability and long‐term electrochemical stability, highlighting the promise of noble‐metal‐free HE‐LDHs for water splitting.