Few-layered Ti₃C₂T_x MXene synthesized via water-free etching toward high-performance supercapacitors

MXene has drawn considerable attention in energy storage due to particular physicochemical properties. At present, among most near-ambient temperature preparation methods, water is usually served as the main solvent. However, MXene is usually subjected to fast structural degradation on account of water molecules attacking in aqueous solution. Herein, we report a novel water-free etching strategy for synthesizing few-layered Ti₃C₂T_x MXenes in deep eutectic solvents at near-ambient temperature. Benefitting from the absence of water and macromolecular structure of deep eutectic solvents, the as-synthesized few-layered Ti₃C₂T_x (DES-Ti₃C₂T_x) MXene presents abundant -O terminations and low oxidation degree. As a consequence, the DES-Ti₃C₂T_x MXene displays excellent specific capacitance of 320 F/g at 2 mV/s. Impressively, the DES-Ti₃C₂T_x MXene exhibits splendid long-term stability that 97% specific capacitance retention can be acquired over 50 000 cycles at high current density of 50 A/g. Therefore, this study offers a new thought for preparing high performance MXene-based materials by water-free etching method.