Layered crystal materials are an emerging class of compounds with desirable properties for a variety of applications. In particular, the family of two-dimensional (2D) transition metal carbides and nitrides known as MXenes has shown exciting prospects for use in various applications.

However, MXenes have only been synthesized from MAX phases by chemically removing A atoms with aggressive solutions. Because this method generates large amounts of waste, it limits the production scale of MXenes and hinders their usefulness.

In a new study, scientists at the University of Chicago report the direct synthesis of MXenes. They have shown how to make these MXenes much faster and easier, with less toxic by-products.

To design a more efficient and less toxic method, the team used the principles of chemistry, specifically “atom economy,” which attempts to minimize the number of atoms wasted during a reaction.

Scientists have devised new chemical processes to produce MXenes from simple and affordable precursors without the need for hydrofluoric acid. It only requires one step: mixing different chemicals with the metal you plan to use for the layers, then heating the mixture to 1700°F.

Chemistry graduate student Di Wang, co-first author of the paper, said: “Then you open it up, and there they are.”

“These new MXenes are also visually beautiful. They stand upright like flowers – which might even make them better for reactions because the edges are exposed and accessible for ions and molecules to move between the metal layers.

The simpler, less dangerous process opens new possibilities for researchers to develop and investigate new variants of MXenes for different applications, such as multiple metal alloys or different ion aromas. The technology has been tested with the metals titanium and zirconium, but the researchers believe it could be applied to a wide variety of additional combinations.

Magazine reference:

  1. Daniel Robertson and Sarah Tolbert. A direct and clean route to MXenes. Science. DOI: 10.1126/science.ade9914