Two-Dimensional Carbides and Nitrides (MXenes)
Dr. Yury Gogotsi
Charles T. and Ruth M. Bach Distinguished University Professor
Director, A.J. Drexel Nanomaterials Institute
Following the discovery of 2D Ti3C2 in 2011, 2D carbides, oxycarbides, carbonitrdes and nitrides of transition metals known as MXenes  have greatly expanded the nanomaterials family. More than 50 different MXenes have been reported, and the structure and properties of numerous other MXenes have been predicted. Moreover, the availability of solid solutions on M and X sites, multi-element high-entropy MXenes, control of surface terminations, and the discovery of out-of-plane ordered double-M o-MXenes (e.g., Mo2TiC2), as well as in-plane ordered i-MXenes offer a potential for producing dozens of new distinct structures and virtually an infinite number of compositions with unique and useful properties. Majority of MXenes have metallic conductivity, but their surfaces are terminated with O, OH, halogens or chalcogens. The MXene family includes the most conductive 2D materials yet discovered, a consequence of their large carrier density. Inherent to their 2D structure, the charge carriers responsible for MXene’s optical responses and electronic transport are very close to an external interface that has exceptional ability to undergo reversible chemical and electrochemical reactions to add or change surface terminations. By design of the MXene composition, the carrier plasma can be rendered either sensitive to or uncommonly robust against the resulting changes in band structure and state-filling. MXenes offer chemically controlled optical and electronic properties that facilitate new ways of influencing material interactions with electromagnetic waves over visible light, IR, THz and even GHz ranges. Many breakthrough technological advances can be enabled by these chemically responsive, conductive materials.
- A. VahidMohammadi, J. Rosen, Y. Gogotsi, The World of Two-Dimensional Carbides and Nitrides (MXenes), Science, 372, eabf1581 (2021)
Hosted by Dr. Manukyan