Mechanical and electrical properties of Ti₃C₂T_x MXene single flakes

Two-dimensional transition metal carbides and nitrides, known as MXenes, are a large class of materials that are finding numerous applications ranging from energy storage and electromagnetic interference shielding to water purification and antibacterial coatings. While bulk applications of MXenes are rapidly developing, their intrinsic physical property characterization through single-flake measurements remains a largely unexplored area of research. Here, we report the elastic properties of monolayers and bilayers of the most important MXene material to date, Ti₃C₂T_x (T stands for surface termination) measured using nanoindentation with the tip of an atomic force microscope. The effective Young’s modulus of a single layer of Ti₃C₂T_x was found to be 0.33 ± 0.03 TPa, which is the highest among the reported values for solution-processed 2D materials, including graphene oxide. Individual Ti₃C₂T_x flakes also exhibit a high conductivity of 4600±1100 S/cm and field-effect electron mobility of 2.6±0.7 cm²/Vs. We found that the resistivity of individual flakes is only one order of magnitude lower than the resistivity of multilayer Ti₃C₂T_x films, which indicates a surprisingly good electron transport through the surface terminations of different flakes, unlike in many other 2D materials.