A new study explains why the “noble metal” resists oxidation and how surface modifications could unleash its catalytic power.
Gold has long been prized for its stability, but in the world of chemistry, that stability of gold is precisely what has caused the problem. The process of oxygen activation, the first step in many catalytic reactions, occurs on gold only to a very small extent and therefore has limited application in industrial oxidation processes.
While fascinating to chemists, this paradox is also frustrating. This resistance to oxygen is why we see gold as bright and shiny in jewelry and in some historical artifacts that have survived for thousands of years. But it also raises a more fundamental question: if the metal is so good at selective catalysis, why does it have such difficulty with oxygen, the most abundant oxidant on Earth?
Recently, researchers explored this phenomenon at the structural level. Through investigations across different facets of gold, the researchers found that the answer lies in both the chemistry and the atomic-scale architecture of gold’s surfaces.
EPFL scientists explore molecular collisions with gold
The Au(110) and Au(100) surfaces reconstruct to quasi-hexagonal structures. These hexagonal arrangements create a large energy barrier against the dissociation of oxygen molecules. In contrast, this splitting of oxygen atoms is much more easily achieved on gold surfaces, where the atoms are laid out in square or rectangular patterns.
The implication is striking: without this surface reconstruction, gold will oxidize rapidly in ambient conditions. Rather, its atomic geometry serves as a delicate yet strong defensive layer, protecting the metal from corrosive attack.
This knowledge not only elucidates gold’s inertness to oxygen but also provides a viable direction for catalyst design. If the atomic-scale squares or rectangles on these gold surfaces can be stabilized through engineering, we may witness a dramatic increase in catalytic activity for oxidation reactions.
Fundamentally, this research redefines the “nobility” of gold not as a fixed characteristic but as a selectable end-state resulting from its adjustable atomic structure, something that chemists can now carefully tailor.
Journal Reference:
- Santu Biswas and Matthew M. Montemore. Role of Reconstruction in the Inertness of Gold toward Oxygen. Physical Review Letters. DOI: DOI: 10.1103/g3bc-t1qv