Tulane Researchers Explain Why Gold Never Tarnishes: Surface Atoms Self-Reconstruct to Suppress Oxidation a Billion-Fold
A Tulane University study finds gold surface atoms spontaneously reorganize into a denser pattern that blocks oxygen reactions by a billion to a trillion times.
Overview
Gold jewelry and coins can stay bright for centuries without tarnishing, and researchers at Tulane University say they have finally pinned down why. A study by postdoctoral fellow Santu Biswas and associate professor of chemical engineering Matthew Montemore, published in Physical Review Letters on May 21, 2026, found that atoms on gold’s surface spontaneously rearrange themselves into a denser pattern that suppresses oxygen reactions by a factor of one billion to one trillion compared with an unreconstructed surface.
What We Know
- “People have generally thought gold doesn’t tarnish simply because it doesn’t interact strongly with oxygen. What we show is that for two of the most common gold surface types, the surface atoms actually rearrange themselves in a way that makes the gold much more resistant to oxidation,” said Matthew Montemore, associate professor of chemical engineering at Tulane’s School of Science and Engineering.
- The finding was published in Physical Review Letters, volume 136, issue 20, according to ScienceDaily’s account of the study.
- According to Scientific American, the researchers describe the reorganization as a “herringbone pattern” — a zigzag configuration — that transforms the atomic lattice from a simple square shape into a denser hexagonal arrangement. The densely packed hexagonal surface makes it significantly harder for oxygen molecules to attach to and bond with gold atoms.
- Scientific American reports that oxygen can more readily oxidize gold in the brief moment before this reconstruction occurs, since that requires substantially less energy; once the herringbone pattern establishes itself, the surface reaches a stable equilibrium that blocks oxygen from penetrating further.
- “Everyone knows that gold is difficult to oxidize. The thing is, why? What is the proper reason for that?” Santu Biswas, the study’s postdoctoral co-author, told Scientific American, describing the motivation behind the research.
- The suppression effect was independently reported by Phys.org at the same one-billion-to-one-trillion magnitude, and again by GIGAZINE, which described “a very dense pattern” on gold’s surface that keeps oxygen molecules from breaking down and reacting with the metal.
- The discovery also helps explain a long-standing puzzle in catalysis: why gold nanoparticles are effective catalysts even though bulk gold is famously inert. GIGAZINE reports that gold nanoparticles “do not form the densely packed surface reconstruction seen in large gold ingots, which may leave more reactive, square-shaped regions exposed.”
- “If you can trick gold into dissociating oxygen, it can actually become a very effective catalyst for certain reactions. Our work suggests a new strategy for potentially doing that by preventing or reversing these surface rearrangements,” Montemore said, according to Tulane University’s release.
- Biswas told Scientific American that reconstruction could be deliberately disrupted: “You can prevent reconstruction by putting some absorbent on top of the surface. And then the gold can easily oxidize.”
- Per Tulane’s release, the findings could inform gold-palladium catalysts already used in vinyl acetate production, as well as potential applications in carbon monoxide removal and propylene oxide manufacturing.
What We Don’t Know
- The researchers’ underlying Physical Review Letters paper was not directly accessible for this article (the journal’s abstract page returned an access error), so exact crystallographic surface labels and any additional quantitative detail in the paper itself beyond what is reported in the press coverage above cannot be independently confirmed here.
- It is not yet clear how directly the catalytic strategy Montemore describes — deliberately preventing or reversing surface reconstruction — could be engineered at commercial scale, or on what timeline.
Analysis
The finding reframes a question that has lingered since antiquity: gold’s resistance to corrosion has typically been attributed simply to its weak chemical reactivity with oxygen. The Tulane work adds a structural dimension to that explanation — the metal’s surface actively reorganizes itself into a more stable, oxygen-blocking configuration. That same mechanism, run in reverse, is what the researchers point to as a possible route to better gold-based catalysts, since disrupting the protective reconstruction is what allows gold nanoparticles to activate oxygen in industrial reactions where bulk gold would not.