Tunable multimetallic nanoparticle exsolution from high-entropy spinel oxides

Metal nanoparticle exsolution from oxides is a powerful route to generate stable metal-oxide interfaces relevant for catalysis, but controlling the process remains challenging. High-entropy oxides (HEOs) serve as compositionally complex and defect-tolerant host lattices that broaden the scope of this process beyond conventional oxides. Here, we use several in situ X-ray and microscopic techniques to track the structural, chemical, and electronic evolution of spinel-type HEOs during thermally induced exsolution under reducing conditions. We show that exsolution proceeds through composition-dependent pathways dictated by the ability of the host lattice to undergo local structural rearrangements. By varying the nominal B-site composition, we control whether exsolution occurs directly from the spinel lattice or through transient rock salt intermediates. These findings establish metal nanoparticle exsolution from high-entropy spinels as a structure- and composition-governed process and identify local rearrangements as the basis for tuning the exsolved phase composition and extent.