Breakthrough method creates 2D-layered metallic materials

Scientists have developed an efficient and easy method to make atomically-thin metal layers of metals for technological applications.

A research team at the University of Chicago has discovered a new way of making the fabrication of MXene (pronounced max-ene) materials much more efficient, paving the way for their use in high-tech electronics or energy storage methods. 

These materials are made from extremely thin layers of metal, between which scientists can slip different ions for various purposes.

The majority of metals, when shaved, stop reacting like a metal. MXenes, in contrast, have unusually strong chemical bonds that allow them to retain the special abilities of metal, like conducting electricity strongly, while also being easily customisable. 

“You can put ions between the layers to use them to store energy, for example,” said chemistry graduate student Di Wang, one of the researchers involved. 

All of these advantages could make MXenes extremely useful for building new devices — for example, to store electricity or to block electromagnetic wave interference.

Until now, these materials have been extremely difficult to fabricate. They could only be produced through several intensive chemical engineering steps, including heating the mixture at 3,000°F (1650ºC) followed by a bath in hydrofluoric acid.

“This is fine if you’re making a few grams for experiments in the laboratory, but if you wanted to make large amounts to use in commercial products, it would become a major corrosive waste disposal issue,” explained Dmitri Talapin, the leader of the research. 

The UChicago team discovered new chemical reactions that allowed them to make MXenes far more quickly from simple and inexpensive precursors, without the use of hydrofluoric acid. It consists of just one step: mixing several chemicals with whichever metal you wish to make layers of, then heating the mixture at 1,700°F (930ºC). “Then you open it up and there they are,” said Wang.

The easier, less toxic method opens up use cases for MXenes — such as different metal alloys or different ion flavourings. The team tested the method with titanium and zirconium metals, but they think the technique can also be used for many other different combinations.

“These new MXenes are also visually beautiful,” Wang added. “They stand up like flowers—which may even make them better for reactions because the edges are exposed and accessible for ions and molecules to move in between the metal layers.”

The researchers’ findings were published in the journal Science.

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