World's Thinnest Gold Just Two Atoms Thick Created by Scientists

Researchers have created the world's "thinnest unsupported gold" that is just two atoms thick. A team from the University of Leeds in the U.K. say the material measures only 0.47 nanometers in thickness. One nanometer is a billionth of a meter (about 3.3 feet.)

The material is considered to be two-dimensional because all of the atoms—which are laid out in two layers, one on top of the other—are surface atoms. According to a study published in the journal Advanced Science which describes the new material, the 2D gold is comfortably thinner than previous attempts.

"The previous reported thinnest unsupported 2D gold nanosheets have a minimum thickness of 3.6 nanometers," Sunjie Ye, lead author of the study, told Newsweek. "Our work represents the first fabrication of freestanding 2D gold with a sub-nanometer thickness, that is, we have brought 2D gold to sub-nanometer scale, which is a new focus of nanotechnology."

Ultrathin nanomaterials such as these have unique structural features which open up the possibility for numerous applications. However, producing ultrathin 2D metal nanomaterials free of a solid substrate—a surface or material which provides support—poses a significant challenge, according to Ye. Nevertheless, the researchers managed to achieve this by developing a new production technique.

"Synthesis of the gold nanosheets starts with chloroauric acid—an inorganic substance that contains gold," Ye said. "It is reduced to its metallic form in the presence of a 'confinement agent'—a chemical that encourages the gold to form as 2D nanosheet."

According to Ye, the latest development represents a "landmark achievement," which could be particularly beneficial to the medical and electronics industries.

"Not only does it open up the possibility that gold can be used more efficiently in existing technologies, it is providing a route which would allow material scientists to develop other 2D metals," she said in a statement. "This method could innovate nanomaterial manufacturing."

One of the main potential applications for the 2D gold could be as a catalyst to speed up chemical reactions in numerous industrial process.

"Gold is a highly effective catalyst. Because the nanosheets are so thin, just about every gold atom plays a part in the catalysis. It means the process is highly efficient," Stephen Evans, a researcher from Leeds who supervised the study, said in a statement.

"Standard benchmark tests revealed that gold nanoscale sheets were ten times more efficient than the gold nanoparticles conventionally used in industry. Our data suggests that industry could get the same effect from using a smaller amount of gold, and this has economic advantages when you are talking about a precious metal," said Evans.

The 2D gold could also be used to develop artificial enzymes that may form part of water purification technologies in the future or rapid, medical diagnostic tests. Furthermore, because the material is flexible, it has the potential to be used in foldable electronics.

The substance created by Ye and her team is not the world's thinnest supported gold, however. That record goes to a team from the Chinese Academy of Sciences who have fabricated gold sheets that are just one atom in thickness.

"These monatomic-thick gold sheets are fabricated from gold-silver alloys by utilizing the different knock-on energies of gold and silver atoms to electron beam," lead author of the research, Kui Du, said in a statement.

Speaking of the gold created by the Chinese team, Ye said the work was impressive but noted that the gold is "impossible to be separated from the bulk crystal. That is, this gold membrane is always associated with the bulk crystal."

2D gold
The image shows a gold nanosheet that is just two atoms thick. It has been artificially coloured. University of Leeds