Golden in the form of gold monolayer sheets is prepared by etching away titanium carbide (Ti)₃C₂. Slabs of titanium gold carbide (Ti)₃AuC₂.

“When you make a material extremely thin, something unusual happens, just as it did with graphene. The same thing happens with gold,” said Dr. Shun Kashiwaya, a researcher at Linköping University.

“As you know, gold is normally a metal, but if it's an atomic layer thick, it can become a semiconductor instead.”

To create Goldene, Dr. Kashiwaya and his colleagues used a three-dimensional substrate with gold embedded between layers of titanium and carbon. However, coming up with a golden turned out to be difficult.

“We created the basic material with a completely different application in mind,” said Professor Lars Hartmann from Linköping University.

“We started with a conductive ceramic called titanium silicon carbide, which has a thin layer of silicon.”

“Then the idea was to coat the material with gold to make the contacts. However, when the component was exposed to high temperatures, the silicon layer inside the substrate was replaced by gold.”

This phenomenon is called intercalation, and what the researchers discovered was titanium-gold carbide.

For several years, authors have been using titanium gold carbide without knowing how the gold could be exfoliated or panned out.

They accidentally discovered a method that has been used in Japanese forging for more than 100 years.

This is called Murakami's reagent, and it etches away carbon residues and changes the color of steel, such as in knife making. However, it was not possible to use exactly the same recipe as the blacksmith.

“We tried varying the concentration of Murakami's reagent and the etching time. One day, one week, one month, several months. What we noticed was that the lower the concentration and the longer the etching process, the better. But even that wasn't enough,” Dr. Kashiwaya said.

Etching must also be performed in the dark, as the reaction produces cyanide, which dissolves the gold when exposed to light. This step was to stabilize the gold sheet.

A surfactant was added to prevent the exposed two-dimensional sheet from curling up. In this case, it is a long molecule, a surfactant, that separates and stabilizes the sheets.

“The golden sheets sit in a solution, a bit like cornflakes in milk. We use a sort of 'sieve' to collect the gold and examine it under an electron microscope to see if we were successful.” We have that,” Dr. Kashiwaya said.

“Golden's new properties are due to the fact that gold has two free bonds when it is two-dimensional.”

“Thanks to this, future applications could include carbon dioxide conversion, hydrogen production catalysts, selective production of value-added chemicals, hydrogen production, water purification, communications, etc.”

“Additionally, the amount of gold used in today's applications can be significantly reduced.”

team's work It was published in the magazine natural synthesis.

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Shin Kashiwaya other. Golden synthesis consisting of a single atomic layer of gold. nut.synthesizer, published online March 18, 2024. doi: 10.1038/s44160-024-00518-4