Scientists conceive of efficient way to make atomically-thin metal layers

The layers could be used to boost electronics.
Loukia Papadopoulos
A scanning electron microscopy image reveals the beautiful shapes of tiny structures known as MXenes.jpg
A scanning electron microscopy image reveals the beautiful shapes of tiny structures known as MXenes.

University of Chicago 

MXenes are materials made of many extremely thin layers of metal, between which scientists can slip different ions for various purposes. They are particularly adept at enabling new electronics or energy storage methods but they are notoriously hard to produce.

Now, a new breakthrough by scientists with the University of Chicago allows MXenes to be manufactured far more quickly and easily, with fewer toxic byproducts, according to a press release by the institution published on Thursday.

First discovered in 2011, MXenes allowed for metals like gold or titanium to be shaved to create atomic-thin sheets while retaining their special abilities like conducting electricity strongly.

They’re also easily customizable: “You can put ions between the layers to use them to store energy, for example,” said chemistry graduate student Di Wang, co-first author of the paper along with postdoctoral scholar Chenkun Zhou.

These properties could make MXenes extremely useful for building new devices—for example, to store electricity or to block electromagnetic wave interference.

But up to now, the only way to make MXenes involved several intensive chemical engineering steps, including heating the mixture at 3,000°F 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 Ernest DeWitt Burton Distinguished Service Professor of Chemistry at the University of Chicago, joint appointee at Argonne National Laboratory and the corresponding author on the paper.

Just one step

The UChicago team has now discovered new chemical reactions that allow scientists to make MXenes in just one step. The process is simple: simply mix several chemicals with whichever metal you wish to make layers of, then heat the mixture at 1,700°F. “Then you open it up and there they are,” said Wang.

The method is less toxic as it does not require the use of hydrofluoric acid. The team has already tested the method with titanium and zirconium metals, but they claim the technique can also be used for many other different metal combinations.

“These new MXenes are also visually beautiful,” Wang added in the press statement. “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.”

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