Redox-Driven Exsolution and Dissolution Behavior of High-Entropy Spinel Catalysts: A Comparative Study of MnFeCoNiCuO<sub><i>x</i></sub> and MnCoNiCuZnO<sub><i>x</i></sub>
High-entropy oxides (HEOs) offer tunable redox chemistry and thermal stability for catalytic applications. Here, we compare two spinel-type HEOs, MnFeCoNiCuO<sub><i>x</i></sub> and MnCoNiCuZnO<sub><i>x</i></sub>, with similar configurational entropy but different redox behaviors under reverse water-gas shift (RWGS) conditions. Only MnFeCoNiCuO<sub><i>x</i></sub> exhibits reversible exsolution and reincorporation of Fe/Co/Ni/Cu alloy nanoparticles (NPs) during H<sub>2</sub>-CO<sub>2</sub> 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<sup>2+</sup> in MnCoNiCuZnO<sub><i>x</i></sub> 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.
Authors
- Yu‐Chuan Lin (ORCID: https://orcid.org/0000-0002-2229-6354)
- Po-Yang Peng
- Cheng-Chia Kuo
- Ying‐Rui Lu (ORCID: https://orcid.org/0000-0002-6002-5627)
- Chi‐Liang Chen (ORCID: https://orcid.org/0000-0001-8509-0655)
- P.C. Chou
Institutions
- National Synchrotron Radiation Research Center (TW)
- National Cheng Kung University (TW)
Publication Details
- Journal
- ACS Applied Materials & Interfaces
- Published
- 2025-09-02
- DOI
- https://doi.org/10.1021/acsami.5c14624
- Citations
- 1
- Primary Topic
- Catalytic Processes in Materials Science
- Type
- article
- Field-Weighted Citation Impact
- 0.52
Funders
- National Science and Technology Council