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DS: Fachverband Dünne Schichten
DS 13: Focus Session: 2D Transition Metal Carbides, Nitrides and Carbonitrides II (joint session DS/MM/O)
DS 13.1: Invited Talk
Thursday, March 21, 2024, 09:30–10:00, A 053
Computational insights into the surface functionalization and defects in MXenes — •Hannu-Pekka Komsa — Microelectronics Research Unit, University of Oulu, Finland
Two-dimensional (2D) transition metal carbide and nitride MXenes offer rich chemistry with extraordinary properties. The surface of MXenes is terminated by -O, -OH, and -F groups during the synthesis. However, there is limited understanding on how the surface composition depends on the synthesis conditions and on the type of MXene (transition metal, carbon vs. nitrogen, and the number of atomic layers).
We developed a multi-scale computational scheme to simulate the distribution and the thermodynamically favorable composition of the functional groups on the MXene surfaces. We considered the most popular MXene systems such as Ti2C, Ti3C2, Ti2N, Ti4N3, Nb2C, and Nb4C3. The surface accommodates mixtures of functional groups for all considered MXenes with similar distributions regardless of the type of metal, carbon or nitrogen species and number of atomic layers. These findings are shown to be important for an accurate prediction of properties and stability of these materials. Next, we investigated the propensity of metal vacancy formation under synthesis conditions. The results suggest that vacancy formation is crucial step in initiating MXene oxidation. Finally, to support experimental characterization, we simulated the Raman spectra as a function of functional group distribution, temperature, and disorder, and the materials’ response to electron irradiation in electron microscope.
Keywords: MXene; first-principles calculations; surface properties; defects; electrochemistry