Intermittent oxidation kinetics and metal/oxide interfacial undulation

The phenomenon of oxygen adsorption induced surface restructuring is widespread across various metal-oxygen systems, yet its impact on initiating bulk oxide formation remains largely unexplored. Through in situ atomic-resolution electron microscopy observations of surface oxidation of Cu(110) and Cu₈₅Au₁₅(110), we unveil intermittent oxide-film growth modulated by oxygen-induced surface restructuring. This modulation is evidenced by repeated pinning of the Cu₂O growth front at isolated Cu columns of the c(6×{}2)-O reconstruction, owing to required long-range diffusion of Cu and O atoms to the Cu₂O growth front. We reveal that Cu vacancies, generated at the Cu₂O growth front, are injected into the Cu₂O/Cu interface, inducing hill and valley undulation of the Cu₂O film. In contrast, atomic vacancies produced during the Cu₈₅Au₁₅(110) oxidation preferentially migrate into interfaces between Au-rich and Au-poor regions in the bulk, resulting in a flat and adherent Cu₂O film. These findings demonstrate the critical role of oxygen-induced surface restructuring in modulating oxide film growth kinetics and the manipulability of the fate of injected vacancies by alloying, thereby offering insights applicable to a broader range of metal-oxygen systems for fine-tuning oxidation kinetics and enhancing oxide/metal interfacial adhesion.