Element Replacement Approach by Reaction with Lewis Acidic Molten Salts to Synthesize Nanolaminated MAX Phases and MXenes.

By Mian Li, Jun Lu, Kan Luo, Youbing Li, Keke Chang, Ke Chen, Jie Zhou, J. Rosen, L. Hultman, P. Eklund and 5 more. Journal of the American Chemical Society, 2019

1,199 citations recorded by the source corpus.

Nanolaminated materials are important because of their exceptional properties and wide range of applications. Here, we demonstrate a general approach to synthesizing a series of Zn-based MAX phases and Cl-terminated MXenes originating from the replacement reaction between the MAX phase and the late transition-metal halides. The approach is a top-down route that enables the late transitional element atom (Zn in the present case) to occupy the A site in the pre-existing MAX phase structure. Using this replacement reaction between the Zn element from molten ZnCl2 and the Al element in MAX phase precursors (Ti3AlC2, Ti2AlC, Ti2AlN, and V2AlC), novel MAX phases Ti3ZnC2, Ti2ZnC, Ti2ZnN, and V2ZnC were synthesized. When employing excess ZnCl2, Cl-terminated MXenes (such as Ti3C2Cl2 and Ti2CCl2) were derived by a subsequent exfoliation of Ti3ZnC2 and Ti2ZnC due to the strong Lewis acidity of molten ZnCl2. These results indicate that A-site element replacement in traditional MAX phases by late transition-metal halides opens the door to explore MAX phases that are not thermodynamically stable at high temperature and would be difficult to synthesize through the commonly employed powder metallurgy approach. In addition, this is the first time that exclusively Cl-terminated MXenes were obtained, and the etching effect of Lewis acid in molten salts provides a green and viable route to preparing MXenes through an HF-free chemical approach.

Subfields: Materials Chemistry, Mechanical Engineering

View Paper: https://www.semanticscholar.org/paper/345a15a871ed84c73898b56150a3a2b9db4e23d9

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Materials Chemistry

1. Yury Gogotsi
2. Michel W. Barsoum
3. J. Rosen
4. P. Persson
5. P. Simon
6. Varun Natu
7. Armin VahidMohammadi
8. P. Eklund

In Mechanical Engineering

1. Yury Gogotsi
2. L. Hultman
3. J. Rosen
4. P. Eklund
5. P. Persson
6. Jun Lu
7. Varun Natu
8. Maxim Sokol

Citations in the corpus

• 2D Ti3C2Tz MXene Synthesized By Water-Free Etching of Ti3AlC2 in Polar Organic Solvents (2020, background): “showed a one-step molten salt (ZnCl2) etching of MAX phases to synthesize –Cl terminated MXenes.(15) Delamination of these –Cl terminated MXenes to form a stable colloid of single to few layers of MXene has not been reported, possibly because of the absence of intercalated cations and/or the absence”