High‐Entropy Engineering of Cobalt Spinel Oxide Breaks the Activity‐Stability Trade‐Off in Oxygen Evolution Reaction

Abstract The oxygen evolution reaction (OER) remains a key challenge in electrochemical water splitting owing to the inherent activity‐stability trade‐off of conventional catalysts, which suffer from either sluggish kinetics governed by the adsorbate evolution mechanism (AEM) or structural degradation triggered by the lattice oxygen‐mediated mechanism (LOM). Here, a high‐entropy engineering strategy is proposed to break this dilemma via the synthesis of a novel high‐entropy (CoFeNiMnW) ₃ O ₄ spinel oxide. The incorporation of multiple principal elements induces lattice expansion and electronic redistribution, enabling simultaneous improvement of OER activity and durability. The well‐designed (CoFeNiMnW) ₃ O ₄ catalyst delivers a low overpotential of 256 mV at 10 mA cm ⁻² and sustains industrial‐grade durability over 200 h at 500 mA cm ⁻² in alkaline media, surpassing the lower‐entropy counterparts and benchmark RuO ₂ . Combined experimental and computational analyses reveal that high‐entropy engineering suppresses excessive LOM activation while favoring the AEM pathway with a reduced energy barrier. The synergy between a confined LOM process and optimized AEM kinetics effectively circumvents the limitations of linear scaling relationships and lattice oxygen loss, achieving a breakthrough in the activity‐stability balance. This work establishes a paradigm for designing high‐efficiency and robust electrocatalysts through entropy‐driven structural and mechanistic regulation.