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 $\mathrm{C}{\mathrm{u}}_{85}\mathrm{A}{\mathrm{u}}_{15}$(110), we unveil intermittent oxide-film growth modulated by oxygen-induced surface restructuring. This modulation is evidenced by repeated pinning of the $\mathrm{C}{\mathrm{u}}_{2}\mathrm{O}$ growth front at isolated Cu columns of the $c$(6\ifmmode\times\else\texttimes\fi{}2)-O reconstruction, owing to required long-range diffusion of Cu and O atoms to the $\mathrm{C}{\mathrm{u}}_{2}\mathrm{O}$ growth front. We reveal that Cu vacancies, generated at the $\mathrm{C}{\mathrm{u}}_{2}\mathrm{O}$ growth front, are injected into the $\mathrm{C}{\mathrm{u}}_{2}\mathrm{O}$/Cu interface, inducing hill and valley undulation of the $\mathrm{C}{\mathrm{u}}_{2}\mathrm{O}$ film. In contrast, atomic vacancies produced during the $\mathrm{C}{\mathrm{u}}_{85}\mathrm{A}{\mathrm{u}}_{15}$(110) oxidation preferentially migrate into interfaces between Au-rich and Au-poor regions in the bulk, resulting in a flat and adherent $\mathrm{C}{\mathrm{u}}_{2}\mathrm{O}$ 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.