Especially since the Nobel prize for the discovery of graphene in 2010, 2D materials have attracted a lot of attentions which led to an immense increase in investigation of this new class of materials. They can be used in a wide range of applications such as electronics, photonics, as sensors or for energy storage. One of the more recent additions to the 2D family of materials were the transition metal carbides or nitrides, known as MXenes [1]. These materials are produced typically by selective etching of the “A” element from a MAX phase. MAX phases (M_n+1AX_n (n=1, 2, 3, …)) are three-dimensional (3D) layered ternary carbides or nitrides.

Up until now, MXenes are synthesized almost exclusively from MAX powder and thus are available in the form of flakes [2]. The main steps of the MXene synthesis comprise the preparation of the MAX phase powder precursor and the selective chemical etching of the “A” element, mainly aluminum using mostly fluorine-based solutions. Subsequently, the MXene layers might be delaminated to obtain 2D single layer flakes or lower dimensional multilayer structures. In the case, where a thin film is required, drop casting, spraying or other transfer techniques could be used to obtain more or less homogeneous surfaces [3].

A promising technique to obtain homogeneous MXene for larger surface areas, for example for biosensor applications, will be shown in the present work. For that, two Ti-Al-C based MAX phase thin films were prepared using an elemental multilayer approach with a subsequent heating step to obtain a homogeneous thin film [4]. During the following selective etching process using low concentrated hydrofluoric acid and short times the thin layer of Ti₃C₂T_x MXene could be obtained. The obtained MXene was exhaustively studied regarding its morphological and structural properties and its incorporation into a 2D-FET biosensor was proposed.

References
[1]    M. Naguib, M. Kurtoglu, V. Presser, J. Lu, J. Niu, M. Heon, L. Hultman, Y. Gogotsi, M.W. Barsoum, Adv. Mater. 2011, 23, 4248.
[2]    M. Shekhirev, C.E. Shuck, A. Sarycheva, Y. Gogotsi, Prog. Mater. Sci. 2021, 120, 100757.
[3]    A. Macknojia, A. Ayyagari, D. Zambrano, A. Rosenkranz, E. V Shevchenko, D. Berman, ACS Nano 2023.
[4]    C. Torres, R. Quispe, N.Z. Calderón, L. Eggert, M. Hopfeld, C. Rojas, M.K. Camargo, A. Bund, P. Schaaf, R. Grieseler, Appl. Surf. Sci. 2021, 537, 147864.