We’ve been talking about graphene for many, many years. It was supposed to be the material of the future, but it didn’t meet expectations. It has infinite applications, and while it’s true that it has made a difference in some areas, such as in loudspeakers, its potential has been diluted little by little. However, its principle is interesting, and now researchers at the University of Linköping in Sweden have combined the structure of graphene with gold, creating a new material: goldene.
Goldene. This term is a combination of the words "gold" and "graphene." Graphene is a substance composed of sheets of pure carbon atoms arranged in a hexagonal pattern, like a honeycomb. This substance stands out for its strength, flexibility, elasticity, transparency, and lightness. Goldene is similar but with gold atoms.
How did the scientists create goldene? By chance, of course. To create goldene, the researchers used a 3D base material in which they embedded gold between layers of titanium and carbon. Lars Hultman, a professor of thin film physics at Linköping University, explains:
“We had created the base material with completely different applications in mind. 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 contact. But when we exposed the component to high temperature, the silicon layer was replaced by gold inside the base material.”
Schematic of the reaction showing the formation of the gold atomic layer. Image | Nature
The researchers published the results of their research in Nature. An image of their research shows just how the intercalation process works, which is basically how titanium carbide and silicon (Ti3SiC2) transform into titanium carbide and gold (Ti3AuC2), a material the researchers have been using for years. However, they haven't been able to extract the gold layer until now.
The Murakami reagent. Japanese forging is an art in itself. One of its pillars is the Murakami reagent, a component used for countless years to remove carbon residues and change the color of steel. For example, it’s used in knife manufacturing to give the objects a shiny appearance. In their research, Hultman found a way to apply this reagent to titanium carbide and silicon.
“I tried different concentrations of Murakami’s reagent and different time spans for etching. 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 it still wasn’t enough,” Shun Kashiwaya, a co-author of the study, stated.
LiU researchers Shun Kashiwaya and Lars Hultman. Image | Linköping University
The researchers explained that the etching had to be done in the dark because light produces cyanide, which dissolves gold. The last step was to obtain stable gold foils (they tend to curl up). For this task, the researchers used a surfactant: a long molecule that separates and stabilizes the foils. The result is a solution that the researchers describe with an familiar analogy: “Like cornflakes in milk.” To collect the gold flakes, they used a kind of sieve.
Possible applications. According to the researchers, goldene has several applications. Since each atom has six neighbors instead of the twelve that we find in a crystal, future applications could include carbon dioxide conversion, hydrogen-generating catalysis, selective production of value-added chemicals, hydrogen production, water purification, and more. Moreover, researchers stated that goldene could reduce the amount of gold we use in other areas today.
Images | Linköping University | Nature | Unsplash
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