Tradeoff between Mechanical Strength and Electrical Conductivity of MXene Films by Nacre-Inspired Subtractive Manufacturing

Abstract

Traditional strategies, by additive manufacturing, for integrating monolayer Ti₃C₂T_x nanosheets into macroscopic films with binders can effectively improve their mechanical strength, but the electrical conductivity is often sacrificed. Herein, inspired by the aligned nano-compacted feature of nacre, a flexible subtractive manufacturing strategy is reported to squeeze the interlayer 2D spacings by removing the nanoconfined water and interface terminations, leading to the improvement of mechanical strength and stability of Ti₃C₂T_x layered films without sacrificing the electrical conductivity. After the vacuum annealing of Ti₃C₂T_x films at 300 °C (A300), the interlayer 2D spacing decreased ≈0.1 nm with the surface functional groups (═O, ─OH, ─F) and interlayer water molecules greatly removed. The tensile strength (95.59 MPa) and Young's modulus (9.59 GPa) of A300 are ≈3 and ≈2 times improved, respectively. Moreover, the A300 films maintain a metallic electrical conductivity (2276 S cm⁻¹) and show greatly enhanced stability. Compared to the original films, the mechanical strength of the A300 films is enhanced by increasing the interlayer friction and energy dissipation with the decrease of interlayer 2D spacings. This work provides a new way for engineering the self-assembled films with more functions for broad applications.