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

ABSTRACT 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 Co 2+ to Co 3+ , collectively modulating local charge redistribution. This strategy enables facilitated Cu nanoparticle exsolution and alters the exsolution sequence from Cu 0 > Ni 0 > Co 0 in pristine HEO to Cu 0 > Co 0 > Ni 0 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.