In situ atomic-scale imaging of the metal/oxide interfacial transformation

Abstract

Directly probing structure dynamics at metal/oxide interfaces has been a major challenge due to their buried nature. Using environmental transmission electron microscopy, here we report observations of the in-place formation of Cu ₂O/Cu interfaces via the oxidation of Cu, and subsequently probe the atomic mechanisms by which interfacial transformation and grain rotation occur at the interfaces during reduction in an H ₂ gas environment. The Cu ₂O→Cu transformation is observed to occur initially along the Cu ₂O/Cu interface in a layer-by-layer manner. The accumulation of oxygen vacancies at the Cu ₂O/Cu interface drives the collapse of the Cu ₂O lattice near the interface region, which results in a tilted Cu ₂O/Cu interface with concomitant Cu ₂O island rotation. These results provide unprecedented microscopic detail regarding the redox reactions of supported oxides, which differs fundamentally from the reduction of bulk or isolated oxides that requires the formation of new interfaces between the parent oxide and the reduced phase.

Abstract

Metal/oxide interfaces play an important role in heterogeneous catalysis and redox reactions, but their buried nature makes them difficult to study. Here, the authors use environmental transmission electron microscopy to probe the atomic-level transformations at Cu ₂O/Cu interfaces as they undergo redox reactions.