MAX Phases and MXenes Synthesis and Their Electronic Structure

MAX phases are a large family of materials that uniquely combine properties of metals and ceramics. In the Framework of the  ANR projet Maxycrist , the research has allowed to develop crystal growth methods to obtain centimeter-sized crystal of MAX phases, as for example, Cr₂AlC. Single crystal growth of those nano-laminates allows us to determine the anisotropic physical properties which are due to their crystal structure. In particular, « ARPES » measurements give an almost direct assessment of their band structure and of their Fermi surface [1].

We use MAX phase single crystals to synthesize macroscopic MXenes, which are the largest class of 2D materials with a huge potential in many applications [2-4]. In collaboration with Institute Pprime, we introduce for the first time an approach to synthesize macroscopic V₂CT_z MXenes by employing ion-implantation strategy and using single crystal as a precursor material. The synthesized multilayers of V₂CT_z MXenes with lateral size exceeding 25 µm are the largest exfoliated MXenes flakes reported up to now. More importantly the conversion of V₂AlC to 2D V₂CT_z takes 8 h which is 10 times lower as compared to typical protocols used for V₂AlC powder exfoliation. This impressive reduction of etching time is related to the selective damaging of the Al layers induced by ion-implantation that drastically facilitates the chemical etching. This contribution opens new avenues for rapid synthesis of macroscopic MXenes layers and pushes forward the discovery of their fundamental physical properties.

[4] A. Yakusheva, D. Saranin, D. Muratov, P. Gostishchev, H. Pazniak, A. Di Vito, T. Son Le, L. Luchnikov, A. Vasiliev, D. Podgorny, D. Kuznetsov, S. Didenko, A. Di Carlo, Small 18, 2201730 (2022).
[5] H. Pazniak, S. Hurand, N. Guignard, S. Célérier, U. Wiedwald, T. Ouisse, M.-L. David, V. Mauchamp, ACS Appl. Nano Mater., 5, 8029–8037 (2022).