Why Gold Doesn’t Rust: A New Study
June 24, 10:00 PM
A team from Tulane University has uncovered the reason gold remains untarnished. When a fresh surface appears—due to a scratch or the formation of a crystal edge—the gold atoms on that surface reorganize into a denser hexagonal pattern. This rearrangement blocks oxygen molecules from splitting apart and triggering oxidation.
Research Methods
Computational chemists Santo Biswas and Matthew Montemore led the investigation, using quantum-mechanical simulations to model how oxygen molecules behave on two distinct types of gold surfaces. On a reconstructed surface—where the gold atoms have shifted into a new arrangement—oxygen molecules cannot break apart enough to start oxidation. In contrast, a non-reconstructed surface with a square atomic layout gives oxygen the chance to split.
Strikingly, the oxidation rate on a reconstructed surface drops by a factor of a billion to a trillion.
Matthew Montemore noted: ‘Just how much more reluctant reconstructed gold is to oxidize was truly surprising.’
The study also highlighted a known fact since the 1980s: gold nanoparticles catalyze reactions more effectively than bulk gold.
These fresh insights deepen the understanding of what makes gold so resistant to oxidation, which could have major implications for industry and scientific research. For example, the findings may help optimize the use of gold in catalysts and other technologies where its oxidation resistance is critical.