Chemically Stabilized and Functionalized 2D-MXene with Deep Eutectic Solvents as Versatile Dispersion Medium

2D transition metal carbides and nitrides, namely MXenes, are normally synthesized in acidic solutions and are delaminated in basic solutions. This results in versatile materials with unique physical/chemical properties suitable for various practical applications. However, solution-based chemical treatments can affect the chemical structures of MXenes, which accelerates the oxidation reactions and degrades their intrinsic properties. Here, long-term stable Ti₃C₂T_x dispersion in deep eutectic solvents (DESs) that resisted oxidation degradation for up to 28 weeks is demonstrated. As an anti-oxidative dispersion medium, DESs helped prevent oxidation of Ti₃C₂T_x layers due to hydrogen bond accepting and donating molecules passivated surface of the Ti₃C₂T_x. In addition, DES molecules in bulk solution can also be hydrated in the presence of water, which stabilizes reactive oxygen by forming stable DES-water cluster. Therefore, the use of DESs enhanced the delamination of the Ti₃C₂T_x nanosheets, while preventing oxidation of the nanosheets in solution and even in their dried state. As a result, thick and thin films of Ti₃C₂T_x fabricated using DESs exhibited stable sheet resistance in comparison with pristine-Ti₃C₂T_x. In addition, Ti₃C₂T_x dispersed in DESs can be applied as electrodes for electrochemical capacitors, in which they showed higher chemical stability and better performance than pristine Ti₃C₂T_x.