Advancing the Understanding of Oxygen Vacancies in Ceria: Insights into Their Formation, Behavior, and Catalytic Roles.

Oxygen vacancies (O's) in ceria (CeO) are critical structural and electronic features that underpin ceria's remarkable oxygen storage capacity, redox catalytic performance, and wide-ranging applications in catalysis, solid oxide fuel cells, and gas sensors. These vacancies, which result from the removal of oxygen atoms, enable dynamic oxygen exchange between the solid and its environment, profoundly influencing ceria's catalytic properties. The intricate surface structures of ceria play a key role in determining its properties and its interactions with supported metal catalysts. Over the past decade, advancements in state-of-the-art in situ characterizations, first-principles calculations, and emerging machine learning frameworks have significantly enhanced our understanding of the formation mechanisms, behaviors, and catalytic roles of O's. This perspective highlights recent experimental and theoretical progress in ceria surface research, emphasizing the dynamic interplay between surface structures and reactive environments. Additionally, the perspective addresses key challenges in elucidating ceria's defect chemistry and explores opportunities to tailor its properties using multiscale modeling and AI-driven methodologies.