Abstract
<jats:p> High-entropy oxides retain a significantly larger population of oxygen vacancies (OVs) compared to their single-element or binary metal oxide counterparts, highlighting their unique potential as prospective electrocatalytic materials. However, the stabilization of surface oxygen vacancies (S-OVs) is highly challenging due to their inherently dynamic nature generally resulting in defect healing, migration, or initiation of structural collapse under operating conditions. By means of rational high-throughput materials science, we investigate the stability of S-OVs in (Cu-Fe-Ni-Cr-Zn)O <jats:sub>x</jats:sub> high-entropy oxides covering a compositional search space of at least 5 to 35 %. A methodology based on X-ray photoelectron spectroscopy and X-ray absorption spectroscopy is utilized to quantitatively follow the distribution of the OVs across the materials library. For low Zn stoichiometries, (Cu <jats:sub>14</jats:sub> -Fe <jats:sub>13</jats:sub> -Ni <jats:sub>5</jats:sub> -Cr <jats:sub>8</jats:sub> -Zn <jats:sub>4</jats:sub> )O <jats:sub>55</jats:sub> , complete stabilization of S-OVs is achieved even after prolonged exposure to ambient environment. The discovery of S-OV stabilization in our high-entropy oxide system is a prerequisite to exploit the unique properties of this class of materials for electrocatalytic applications and beyond. </jats:p>