Improving CO Oxidation Catalysis Over High Entropy Spinels by Increasing Disorder
Joshua D. Swindell, Gareth R.M. Tainton, Sarayute Chansai, Kerry Hazeldine, Mark A. Buckingham, Alex S. Walton, Christopher Hardacre, Sarah J. Haigh, David J. Lewis
Abstract
Abstract Enhancing the activity and stability of earth‐abundant, heterogeneous catalysts remains a key challenge, requiring new materials design strategies to replace platinum‐group metals. Herein, it is demonstrated that increasing the configurational disorder of spinel metal oxides (M 3 O 4 , where M is a combination of Cr, Mn, Fe, Co, Ni, Cu, and Zn) leads to significant improvements in carbon monoxide (CO) oxidation performance. A substantial 63% decrease in the T 10 value (temperature to reach 10% CO oxidation) is observed by systematically increasing the number of first‐row transition metals within the spinel oxide. Long‐term stability studies reveal that the most disordered 7‐metal spinel oxide exhibited superior resistance to catalyst deactivation compared to the 4‐metal variant, showing a decrease in activity of only 4.7% versus 12.2% during 14 h of operation. A solventless thermolysis approach is developed to synthesize a series of medium entropy spinel oxide (MESO) and high entropy spinel oxides (HESOs) from discrete, air‐stable molecular precursors. Comprehensive crystal structure determination, elemental distribution analysis, and surface characterization are conducted, establishing a clear structure‐function relationship between elemental composition, configurational disorder, and catalytic performance. This work highlights how configurational disorder can serve as an effective design principle for developing both active and stable catalysts.