Amorphous High-Entropy Oxides With High-Valent Metal and Oxygen-Vacancy Pairs for Thermally Stable Catalytic Oxidation.
basic_science · Level V
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- Record sourced from PubMed, PMID 42412391.
- Also identified by DOI 10.1002/adma.74010.
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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<sub>x</sub> HEO (MYZrO<sub>x</sub>-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<sub>x</sub>-a retains short‑range disorder and abundant defect sites even after calcination at 600°C. Moreover, the stabilized high‑valence metal-oxygen vacancy (M<sup>δ+</sup>-O<sub>v</sub>) pairs facilitate the activation of C─H bonds and oxygen species, endowing MYZrO<sub>x</sub>-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.