Fluoride-Free Synthesis of 2D Titanium Carbide (MXenes) Assisted by scCO 2 -Based Ternary Solution.

2D MXene-Ti 3 C 2 T x holds great promise in various electronic applications, especially for electromagnetic interference (EMI) shielding devices and supercapacitors. Ti 3 C 2 T x synthesis typically involves the use of hazardous fluorine-containing chemicals that can result in the formation of inert fluoride functional groups on the surface of Ti 3 C 2 T x , severely degrading its properties and posing a threat to the performance of electron transfer among electrical devices. Herein, a supercritical carbon dioxide-based ternary solution (scCO 2 /DMSO/HCl) to produce fluoride-free Ti 3 C 2 T x in mild conditions (via 0.5 m HCl, 20 MPa, 32 °C) is reported. The fluorine-free Ti 3 C 2 T x films electrode presents an excellent gravimetric capacitance of 320 F g -1 at 2 mV s -1 in 1 m H 2 SO 4 . Besides, it is demonstrated that fluorine-free Ti 3 C 2 T x films exhibit outstanding EMI shielding efficiency of 53.12 dB at 2.5 µm thickness. The findings offer a mild and practical approach to producing fluoride-free Ti 3 C 2 T x and open opportunities for exploring MXenes' potential applications in various fields.