MXenes are large family of two-dimensional (2D) transition metal carbides and nitrides of Mn+1XnTz composition; where M is an early transition metal (e.g. Ti, V, Mo, Nb) and X is either carbon or nitrogen, “Tz” stands for a mixture of surface terminations (e.g. O, OH, F, Cl), and n can be 1, 2, or 3. So far, about two dozens of MXenes have been produced experimentally (e.g. Ti3C2, V2C, Nb2C, Mo2C, (V0.5,Cr0.5)3C2, Ti3CN, Ta4C3, and Nb4C3). In addition, ab initio calculations predicted many others to be stable. Combining the metallic conductivity of transition metal carbide/nitrides with the hydrophilic nature of their terminated surfaces place MXenes in a unique position among all other 2D materials.
MXenes can be intercalated by a wide range of intercalants from mono- and multi-valent ions to organic and inorganic molecules. Since their discovery, intercalation has been of a critical importance for MXenes processing and applications including electrochemical energy storage, water purification and sensing. However, very little has been known for the nature of intercalant and the bonding between MXenes surface and the intercalant. Using various neutron scattering techniques, we studied MXenes intercalation for two systems: Ti3C2/ion/water and Ti3C2/urea/water. In this presentation, the recent fundamental findings and understanding for the complexity of intercalations in MXenes, will be discussed. In addition, the performance of MXenes as electrode materials hosting ions for batteries, and the effect of ions intercalation on the structure and behavior of MXenes will be presented.
Michael Naguib is an assistant professor in the department of Physics and Engineering Physics at Tulane University, New Orleans, Louisiana, USA. Prior to joining Tulane in 2018, he was a Eugene Wigner Fellow (2014-2017) and Research Staff (2017-2018) at Oak Ridge National Laboratory. He earned his Ph.D. in Materials Science and Engineering at Drexel University in 2014. He is an inventor on the first patent on two-dimensional transition metals carbides and carbonitrides, so-called MXenes. He has published 59 papers (with more than 8000 citations) in international journals and presented many invited talks at number of international conferences and universities. He has received many awards, such as Robert L. Coble Award, Kroto Award, Ross Coffin Purdy Award, MRS Gold Graduate Student Award, Graduate Excellence in Materials Science (GEMS) Award, and was listed as Drexel University Forty- Under-Forty. His research focuses on the synthesis and characterization of novel ceramics materials for electrochemical energy storage and energy conversion.