Amorphous High‐Entropy Oxides With High‐Valent Metal and Oxygen‐Vacancy Pairs for Thermally Stable Catalytic Oxidation

Abstract

ABSTRACT High‐entropy oxides (HEOs) show great promise in heterogeneous catalysis due to their unique structural properties. However, stabilizing the amorphous structure of HEOs under high‐temperature conditions remains challenging. Herein, we propose a thermodynamic synergy‐driven strategy to construct the long‐range disordered structure in HEO, achieving the preservation of defect‐rich sites with high thermal stability. By integrating multiple metal elements with substantial atomic size differences, we construct an amorphous MnFeCoNiCuYZrO x HEO (MYZrO x ‐a), in which the high configurational entropy creates a thermodynamic barrier against amorphous‐to‐crystalline transition. This strategy also demonstrates both universality and scalability for synthesizing thermally stable amorphous HEOs. Combined experimental characterization and theoretical calculations reveal that MYZrO x ‐a retains short‑range disorder and abundant defect sites even after calcination at 600°C. Moreover, the stabilized high‑valence metal–oxygen vacancy (M δ+ –O v ) pairs facilitate the activation of C─H bonds and oxygen species, endowing MYZrO x ‐a with exceptional methane combustion activity and durability, with stable performance exceeding 200 h even under high‑humidity conditions. This work underscores the pivotal role of configurational entropy in designing amorphous HEOs and expands their potential for advanced thermocatalytic applications.