To test their hypothesis, the scientists analyzed cupric oxide, a copper oxide that many researchers are interested in because it is more abundant and affordable than noble metals such as silver, gold and platinum, and it is used for numerous processes such as methanol production.

The team examined the reaction between hydrogen and copper oxide using atomic-scale transmission electron microscopy. The technique allowed them to see the surface and subsurface simultaneously and in real-time, showing that structural oscillations are induced in the subsurface by loss of oxygen from the oxide surface.

“This study shows how the reaction from the surface propagates to deeper atomic layers. We look at it from a cross-section so we can see atoms both in the top layer and subsurface layers more clearly,” said the senior author of the study, Guangwen Zhou, in a media statement. “We can’t care just about the surface but also the deeper layers if we want to understand the process better. If we know these reaction mechanisms, we can design better materials.”