High Entropy-Driven Role of Oxygen Vacancies for Water Oxidation

Oxygen vacancy engineering is a promising strategy to enhance the electrocatalytic activities in conventional metal oxide electrocatalysts. However, the utilization of oxygen vacancies in high-entropy oxides remains unknown, primarily due to the challenges associated with facile introduction of the oxygen vacancies and explanation of their roles in complex high-entropy systems. Herein, the facile introduction of oxygen vacancies into high-entropy oxides is realized and the unique high entropy-driven role of oxygen vacancies for oxygen evolution reaction (OER) process is revealed. A low-temperature surface carbonization–decarbonization approach is developed to introduce and regulate the oxygen vacancies in high-entropy spinel oxides (HEOs). The oxygen vacancies in HEOs can both facilitate pre-oxidation process for faster OH⁻ adsorption and induce the unique bridge site pathway for easier deprotonation, distinctive in conventional oxides where oxygen vacancies favor ^*OH adsorption yet hinder the deprotonation. Consequently, the as-prepared high-entropy spinel oxides with oxygen vacancies (HEOs-Ov) exhibit superior OER activities, outperforming the HEOs and most reported oxide-based electrocatalysts. Besides, this universal method can be extended to other spinel oxides with different configuration entropies and can be scaled up. The work paves the way for the exploration of oxygen vacancies in high-entropy oxides toward electrocatalysis fields.