Evrim Yazgin
Cosmos science journalist
Move over, graphene. Your blinged-up cousin, goldene, has entered the scene.
Researchers have accidentally created a single-atom layer of gold.
The new material has been dubbed “goldene” because it replicates the two-dimensionality of the carbon-based graphene.
Graphene was discovered in 2004 after being theoretically suggested as far back as 1985.
In the 20 years since its first production, graphene has taken the world by storm, showing its usefulness in applications from semiconductors in ultra-fast computers to making tiny carbon nanotubes stronger than diamond.
The researchers who created goldene believe its properties could make it useful in applications such as carbon dioxide conversion, hydrogen production and the manufacture of other chemicals.
The goldene breakthrough is detailed in a paper published in Nature Synthesis.
“If you make a material extremely thin, something extraordinary happens – as with graphene,” says first author Shun Kashiwaya, researcher at Linköping University, Sweden. “The same thing happens with gold. As you know, gold is usually a metal, but if single-atom-layer thick, the gold can become a semiconductor instead.”
Like graphene, scientists have long tried to make goldene, but failed. This is because the metal tends to clump together.
A 100-year-old Japanese smithing method allowed the breakthrough at Linköping. And it was all a bit of an accident.
Using a 3D base material, the researchers embedded gold between layers of titanium and carbon.
“We had created the base material with completely different applications in mind,” says senior author Lars Hultman, a professor at Linköping. “We started with an electrically conductive ceramic called titanium silicon carbide, where silicon is in thin layers. Then the idea was to coat the material with gold to make a contact. But when we exposed the component to high temperature, the silicon layer was replaced by gold inside the base material.”
Hultman found a Japanese forging method called Murakami’s reagent used for etching away carbon residue. Modifying the method, the team was able to get the gold out of the structure.
The final step in the process is to make gold sheets which are stable.
“The goldene sheets are in a solution, a bit like cornflakes in milk. Using a type of ‘sieve,’ we can collect the gold and examine it using an electron microscope to confirm that we have succeeded. Which we have,” says Kashiwaya.
Gold atoms in goldene are arranged in a triangular pattern, unlike graphene in which the carbon atoms form hexagons.
