Materials consisting of only one or a couple of atomic layers, often referred to as two-dimensional materials, are a highly intense field of research. The best-known example is graphene, which earned the research team behind its discovery the Nobel Prize in 2010. The electron microscope ARWEN at Linköping University is one of Europes sharpest. Photo credit Magnus Johansson Thanks to their thinness, these materials may have unexpected properties such as excellent electrical and thermal conductivity or extreme heat resistance.
One class of such two-dimensional materials is called MXenes. They consist of a metal in combination with either carbon or nitrogen atoms. In contrast to other two-dimensional materials, MXenes are metallically conductive. The properties of MXenes open up for their use in technical applications such as batteries and supercapacitors, air and water cleaning filters and antennas for next generation communication.
Researchers at Linköping, in collaboration with colleagues in the US and China, have now elaborated a new method for developing new MXenes that can be tailored at atom level using a “chemical scissor”.
“The atoms become like LEGO blocks that can be moved around in the material any way you like. Thanks to the chemical scissor, there are now huge possibilities to develop new materials with exciting and unexpected properties,” says Per Persson, professor at the Department of Physics, Chemistry and Biology (IFM) at Linköping University.Per Persson, professor at the Department of Physics, Chemistry and Biology. Photo credit Olov Planthaber
A “chemical scissor” is a molecule designed to react with specific chemical compounds, so that the bonds in a material can be broken in exactly the right place. The technology to break carbon-hydrogen bonds in organic molecules has existed for more than a decade. But what researchers have shown now, in their article published in Science, is that the scissor can also break strong bonds in two-dimensional materials such as MXenes.
Create unthinkable materials
MXenes are created from a three-dimensional precursor material called a MAX phase, consisting of three different substances: M is a transition metal, A is a chemical element such as aluminium or silicon, and X is carbon or nitrogen. By using acids to etch away the A part, a two-dimensional material – a MXene – is created.
Previously, the potential for MXenes was limited by the way they are produced and the finite number of MAX phases. This meant that, in practice, it was possible to create some thirty MXenes, although with limited manufacturing precision. Using the “chemical scissor” already on the MAX phase allows for the creation of completely new MXenes.Per Eklund, professor at the Department of Physics, Chemistry and Biology. Photo credit Olov Planthaber
“We can now develop previously unthinkable materials with high precision, where we can cut apart structures and stitch them back together again as we like, and also control their properties, to enable new applications,” says Per Eklund, professor at IFM.
The study was supported by the Swedish Government Strategic Research Area in Materials Science on Functional Materials – AFM – at Linköping University, the Swedish National Infrastructure in Advanced Electron Microscopy – ARTEMI, the Knut and Alice Wallenberg Foundation, and others.
Article: Chemical scissor–mediated structural editing of layered transition metal carbides; Haoming Ding, Youbing Li, Mian Li, Ke Chen, Kun Liang, Guoxin Chen, Jun Lu, Justinas Palisaitis, Per O. Å. Persson, Per Eklund, Lars Hultman, Shiyu Du, Zhifang Chai, Yury Gogotsi, Qing Huang; Science Vol 379; published online on 16 March 2023. DOI: 10.1126/science.add5901.
An electron microscope image of a MAX-phase.
Photo credit ARWEN