Fast and High-Yield Anhydrous Synthesis of Ti3C2Tx MXene with High Electrical Conductivity and Exceptional Mechanical Strength

Abstract

2D transition metal carbides or nitrides (MXenes) have attracted considerable attention from materials scientists and engineers owing to their physicochemical properties. Currently, MXenes are synthesized from MAX-phase precursors using aqueous HF. Here, in order to enhance the production of MXenes, an anhydrous etching solution is proposed, consisting of dimethylsulfoxide as solvent with its high boiling point, NH4HF2 as an etchant, CH3SO3H as an acid, and NH4PF6 as an intercalant. The reaction temperature can be increased up to 100 degrees C to accelerate the etching and delamination of Ti3AlC2 MAX crystals; in addition, the destructive side reaction of the produced Ti3C2Tx MXene is suppressed in the etchant. Consequently, the etching reaction is completed in 4 h at 100 degrees C and produces high-quality monolayer Ti3C2Tx with an electrical conductivity of 8200 S cm(-1) and yield of over 70%. The Ti3C2Tx MXene fabricated via this modified synthesis exhibits different surface structures and properties arising from more F-terminations than those of Ti3C2Tx synthesized in aqueous HF2T. The atypical surface structure of Ti3C2Tx MXene results in an exceptionally high ultimate tensile strength (167 +/- 8 MPa), which is five times larger than those of Ti3C2Tx MXenes synthesized in aqueous HF solution (31.7 +/- 7.8 MPa).