Computational Discovery and Properties of Novel MXenes

Since their discovery one decade ago, the MXenes have developed into the largest family of two dimensional materials with a broad array of predicted and reported properties. Theory and computation have been useful to explore many variations from the standard (M_n+1X_nT_x) formula, chiefly by varying the M atom to consider alloys and their possible ordering. Some of the variations include ordered multi-metal atom MXenes, where the different species of metal atoms are ordered in different layers, and more recently high-entropy MXenes where many metal atoms form a solid solution. These all result in different structural and electronic properties. In this presentation I will first review the range of structures that have been predicted in the MXene family. Second, I will consider some of the surprising opportunities remaining for new materials, based on the results from recent high throughput density functional calculations looking at variations on the “X” site, where we have studied many seemingly overlooked borides, nitrides, and their alloys with carbon. Results are contrasted with the established properties of Ti₃C₂. Finally, looking forward to the next few years of MXene research, I will outline some of the properties that have remained out-of-reach and the challenges posed to theory by recent experiments.<br/><br/>This research was sponsored by the Fluid Interface Reactions, Structures, and Transport (FIRST) Center, an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences.