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Improving CO Oxidation Catalysis Over High Entropy Spinels by Increasing Disorder
Joshua D Swindell1, Gareth R M Tainton1, Sarayute Chansai2
1Department of Materials, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK.
Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
|February 21, 2025
Summary
Configurational disorder in spinel metal oxides significantly boosts carbon monoxide (CO) oxidation. Increasing metal elements in these earth-abundant catalysts improves both activity and stability, offering a promising alternative to precious metals.
Area of Science:
- Materials Science
- Catalysis
- Inorganic Chemistry
Background:
- Developing active and stable heterogeneous catalysts from earth-abundant materials is crucial for replacing platinum-group metals.
- Spinel metal oxides (M3O4) offer a versatile platform for catalyst design, but their performance is often limited by composition and structure.
- Configurational disorder is an emerging strategy to tune catalyst properties.
Purpose of the Study:
- To investigate the impact of configurational disorder in spinel metal oxides on catalytic performance for carbon monoxide (CO) oxidation.
- To establish a structure-function relationship between elemental composition, disorder, and catalytic activity/stability.
- To develop a synthesis method for medium entropy spinel oxides (MESOs) and high entropy spinel oxides (HESOs).
Main Methods:
- Synthesis of a series of spinel metal oxides with varying numbers of first-row transition metals (Cr, Mn, Fe, Co, Ni, Cu, Zn) using a solventless thermolysis approach.
- Evaluation of catalytic activity through carbon monoxide (CO) oxidation performance, specifically measuring the T10 value (temperature for 10% CO oxidation).
- Long-term stability testing of catalysts under reaction conditions and comprehensive characterization including crystal structure, elemental distribution, and surface analysis.
Main Results:
- Increasing configurational disorder by incorporating more transition metals into the spinel oxide structure significantly enhanced CO oxidation activity, with a 63% decrease in the T10 value.
- The most disordered 7-metal spinel oxide demonstrated superior long-term stability, with only a 4.7% decrease in activity over 14 hours compared to a 12.2% decrease for a 4-metal variant.
- A clear correlation was established between higher configurational disorder, specific elemental compositions, and improved catalytic performance.
Conclusions:
- Configurational disorder is an effective materials design principle for enhancing both the activity and stability of earth-abundant heterogeneous catalysts.
- Medium entropy spinel oxides (MESOs) and high entropy spinel oxides (HESOs) show great promise for CO oxidation and potentially other catalytic applications.
- This approach provides a viable strategy for developing advanced catalysts without relying on expensive platinum-group metals.
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