Unraveling the Stability Mechanism of Ru‐Based High‐Entropy Oxides for Oxygen Evolution Reactions by the First‐Principles Method

Abstract It has been experimentally reported that Ru‐based high‐entropy oxides (Ru‐HEO) exhibit higher stability and durability in acidic oxygen evolution reaction (OER) compared to RuO 2 . However, the underlying stability mechanism remains unclear. Herein, the surface states of Ru‐HEO and RuO 2 are first studied as a function of applied potential and pH to elucidate the poisoning or oxidation of Ru active sites under OER electrocatalytic conditions. Subsequently, the formation energies of oxygen vacancies on various Ru‐HEO surface states are calculated, which are typically associated with structural instability due to the lattice oxygen oxidation mechanism. The results indicate that the presence of metal atoms in Ru‐HEO strengthens the Ru─O bond, possibly contributing to the long‐term stability of Ru‐HEO OER catalysts. This work provides insights into the origin of Ru‐HEO stability by comparison with RuO 2 .