Electrical and Elastic Properties of Individual Single‐Layer Nb₄C₃T<i>_x</i> MXene Flakes

Abstract 2D carbides and nitrides (MXenes) are widely recognized for their exceptional promise for numerous applications. However, physical property measurements of their individual monolayers remain very limited despite their importance for revealing the intrinsic physical properties of MXenes. The first mechanical and electrical measurements of individual single‐layer flakes of Nb 4 C 3 T x MXene, which are prepared via an improved synthetic method are reported. Characterization of field‐effect transistor devices based on individual single‐layer Nb 4 C 3 T x flakes shows an electrical conductivity of 1024 ± 165 S cm −1 , which is two orders of magnitude higher than the previously reported values for bulk Nb 4 C 3 T x assemblies, and an electron mobility of 0.41 ± 0.27 cm 2 V −1 s −1 . Atomic force microscopy nanoindentation measurements of monolayer Nb 4 C 3 T x membranes yield an effective Young's modulus of 386 ± 13 GPa, assuming a membrane thickness of 1.26 nm. This is the highest value reported for nanoindentation measurements of solution‐processable 2D materials, revealing the potential of Nb 4 C 3 T x as a primary component for various mechanical applications. Finally, the agreement between the mechanical properties of 2D Nb 4 C 3 T x MXene and cubic NbC suggests that the extensive experimental data on bulk carbides could be useful for identifying new MXenes with improved functional characteristics.