Improving CO Oxidation Catalysis Over High Entropy Spinels by Increasing Disorder

Developing earth-abundant heterogeneous catalysts that are simultaneously highly stable and active remains a key challenge within material science that requires novel design strategies. Transition metal spinel oxides exhibit desirable catalytic properties but are prone to long-term degradation. We present a significant improvement to the catalytic activity and long-term stability of spinel oxides (M3O4, where M is a combination of Cr, Mn, Fe, Co, Ni, Cu, and Zn) for CO oxidation by systematically increasing the configurational disorder. We revealed an impressive 63% reduction in the T10 value (temperature to reach 10% CO oxidation) by increasing the number of first-row transition metals within the spinel structure from 4 to 7 metals. The most disordered 7-metal spinel structure was also found to exhibit superior resistance to catalyst deactivation compared to the 4-metal spinel. A facile, versatile molecular precursor-driven approach to synthesizing a series of high-entropy spinel oxides (HESO) is also presented, along with comprehensive characterization of the crystal structure (XRD/atomic resolution STEM), elemental distribution (EDS), and surface (XPS).