Chou Pei-Tung, Kuo Cheng-Chia, Peng Po-Yang, Lu Ying-Rui, Chen Chi-Liang, Lin Yu-Chuan
Department of Chemical Engineering, National Cheng Kung University, Tainan 70101, Taiwan.
National Synchrotron Radiation Center, Hsinchu 30076, Taiwan.
ACS Appl Mater Interfaces. 2025 Sep 17;17(37):52315-52324. doi: 10.1021/acsami.5c14624. Epub 2025 Sep 2.
High-entropy oxides (HEOs) offer tunable redox chemistry and thermal stability for catalytic applications. Here, we compare two spinel-type HEOs, MnFeCoNiCuO and MnCoNiCuZnO, with similar configurational entropy but different redox behaviors under reverse water-gas shift (RWGS) conditions. Only MnFeCoNiCuO exhibits reversible exsolution and reincorporation of Fe/Co/Ni/Cu alloy nanoparticles (NPs) during H-CO cycling, as confirmed by in situ X-ray absorption spectroscopy and wavelet-transformation. This dynamic restructuring correlates with higher concentrations of oxygen vacancy and exsolved Fe/Co/Ni/Cu alloy NPs, resulting in higher RWGS activity above 400 °C. In contrast, redox-inert Zn in MnCoNiCuZnO suppresses lattice flexibility and alloy formation. These findings underscore that redox-active cations, rather than entropy alone, govern the regenerative behavior and catalytic performance in HEO systems.
高熵氧化物（HEOs）为催化应用提供了可调节的氧化还原化学性质和热稳定性。在此，我们比较了两种具有相似组态熵但在逆水煤气变换（RWGS）条件下具有不同氧化还原行为的尖晶石型高熵氧化物，即MnFeCoNiCuO和MnCoNiCuZnO。原位X射线吸收光谱和小波变换证实，只有MnFeCoNiCuO在H-CO循环过程中表现出Fe/Co/Ni/Cu合金纳米颗粒（NPs）的可逆析出和再掺入。这种动态重构与较高浓度的氧空位和析出的Fe/Co/Ni/Cu合金NPs相关，从而在400℃以上具有更高的RWGS活性。相比之下，MnCoNiCuZnO中氧化还原惰性的Zn抑制了晶格灵活性和合金形成。这些发现强调，在高熵氧化物体系中，氧化还原活性阳离子而非仅熵决定了再生行为和催化性能。
