Scientists develop a solution for preparing macroscopic two-dimensional MXenes

Mar 10, 2020
Scientists develop a solution for preparing macroscopic two-dimensional MXenes (Nanowerk News) Scientists at the Institute of Solid State Physics (ISSP), Hefei Institutes of Physical Science reported that they have obtained the macroscopic V4C3Tx MXene by wet-chemical method (Inorganic Chemistry, "Achieving Macroscopic V4C3Tx MXene by Selectively Etching Al from V4AlC3 Single Crystals").
MXene is a new kind of two-dimensional (2D) material, which are synthesized by chemical etching the "A" layers of MAX phase compounds.

Macroscopic V4C3Tx MXenes (right) obtained by hydrofluoric acid (HF) selectively etching the Al layers of V4AlC3 single crystals (left); The crystal structure diagram of V4AlC3 (middle). (Image: LIN Shuai)
MXenes have shown promises in electrochemical energy storage, electromagnetic interference shielding, sensor, catalysis and so on. Besides, they also have exhibited outstanding performances in electronic and photonic applications based on their metallic conductivity, tunable work function, and adjustable band gap, which is a fast-emerging field of MXene research with huge potential.
In general, the obtained MXenes are micron size or even smaller because they are usually produced by etching micron-size (<38 µm) MAX phase polycrystalline powders.
Such a small size of MXene materials limits their applications in electronic and photonic devices. How to obtain 2D MXene materials with large size or even macroscopic size has become an urgent problem to be solved.
For this purpose, the researchers in ISSP firstly grew millimeter-scale V4AlC3 single crystals by high-temperature flux method. And then, V4AlC3 single crystals were immersed in hydrofluoric acid at room temperature for 40 days.
As a result, the Al layers of V4AlC3 single crystals were selectively etched, resulting in the formation of macro-sized V4C3Tx MXene (as shown in Fig. above).
Obtaining of macroscopic V4C3Tx MXene will not only provide the possible to probe its application in electronic and photonic devices but also stimulate the preparation and applications of other macroscopic MXene materials.

Source: Chinese Academy of Sciences

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