Atomic scale understanding of Cu oxidation

Accurate prediction of oxide structure has long been a major challenge in corrosion science, and is becoming increasingly important for advanced nanomanufacturing. Although high-temperature corrosion is a relatively well-established field of study, it is still based on classical models such as Wagner’s model, which lack consideration at the microstructural level. Therefore, these models are less accurate in explaining earlier stages of oxidation and cannot predict how factors such as surface orientations, defects, and boundaries affect the oxidation process. This is because experimental tools capable of observing this decisive early-stage oxidation have formerly been unavailable, and success in generating a predictive understanding requires the integrated efforts of a diverse group of researchers. Developments involving in situ environmental TEM (ETEM) have demonstrated the great promise of this capability. However, methods for analyzing the in situ data to extract meaningful information are challengin. Here we present in situ ETEM experiments, with advanced data analysis and correlated theoretical simulations, to investigate the initial stages of Cu oxidation, from the missing-row Cu-O surface reconstruction, oxide nucleation to its monolayer-by-monolayer island growth. These dynamic experimental atomic-scale observations, correlated with multiscale simulations, provide critical and fascinating new insights into the initial oxidation mechanisms of metals and alloys.