Atomically thin, two-dimensional (2D) materials have unique properties compared to their conventional three-dimensional counterparts. Graphene, which is a single atomic layer of carbon, is the most illustrious and studied of these newly emerging 2D materials. However, graphene is limited to just carbon in its composition. Recently, a new family of 2D early transition metal carbides and carbonitrides – so called “MXene”- were synthesized by our group via selective etching of the ‘A’ elements in the corresponding MAX phases. These 2D materials offer a large variety of chemical compositions compared to graphene and they can exist as 3, 5, or 7 atomic layer-thick compounds. The resulting MXene flakes are have a highly conductive transition metal carbide/nitride core with surface functional groups (i.e. -O, -OH, -F). As a result of having possessing surface charge and having surface terminations that render a hydrophillic character, MXenes can be thought of as “conductive clays” in which cation intercalation and exchange can easily occur. To date more than 15 MXenes with different transition metal, or mixed transition metal surfaces, have been synthesized. Our goal is to master the synthesis of MXenes and comprehensively study their fundamental physical properties.
MXenes may have a wide range of potential applications, including energy storage, polymer nanocomposite fillers, water purification, transparent optical conductive coatings, electromagnetic shielding/absorption, and electronic devices. Before the best application can be identified, however, the fundamental physics of these materials must be understood and the synthesis-structure-property relationships must be established. By combining experimental and theoretical work, we hope to understand the surface chemistries and the processing-structure- properties of MXenes. For a comprehensive review of MXene research to date, see the recent review article by Ng et al.