Controlling Exsolution Dynamics in High-Entropy Oxides for Highly Active and Selective Acetylene Semi-Hydrogenation

Exsolution-derived catalysts feature robust metal-support interactions that enhance catalytic performance; yet achieving precise control over exsolution dynamics in multicomponent oxides remains challenging. In this study, we demonstrate that exsolution behavior in high-entropy oxides (HEOs) can be rationally tuned through coupled lattice- and valence-engineering to create a highly active and selective catalyst for acetylene semi-hydrogenation. Incorporation of Li⁺ into a rock salt-structured HEO (LiNiMgCuZnCoO_x and LiHEO) induces local lattice distortion, generates oxygen vacancies, and partially oxidizes Co sites from Co²⁺ to Co³⁺, collectively modulating local charge redistribution. This strategy enables facilitated Cu nanoparticle exsolution and alters the exsolution sequence from Cu⁰ > Ni⁰ > Co⁰ in pristine HEO to Cu⁰ > Co⁰ > Ni⁰ in the LiHEO. The resulting catalyst via controlled exsolution exhibits superior activity and ethylene selectivity, outperforming state-of-the-art transition metal systems. This work establishes entropy-enabled lattice and valence engineering as a facile route to programmable exsolution for enhanced catalysis.