MXenes are prone to oxidize and degrade quickly in a matter of days. Here, the use of antioxidants, such as sodium L-ascorbate, is demonstrated as an effective approach to arrest the oxidation of colloidal and dehydrated Ti 3 C 2 T x MXene nanosheets. The success of the method is evident as the Ti 3 C 2 T x nanosheets maintain their composition, morphology, electrical conductivity, and colloidal stability. This method addresses the most pressing challenge in the field of MXene engineering.

Ti 3 C 2 T x belongs to the family of MXenes, 2D materials with an attractive combination of functional properties suitable for applications such as batteries, supercapacitors, and strain sensors. However, the fabrication of devices and functional coatings based on Ti 3 C 2 T x remains challenging as they are prone to chemical degradation by their oxidation to TiO 2. In this paper, we examine the oxidation of Ti 3 C 2 T x in air, liquid, and solid media via conductivity measurements to assess the shelf life of Ti 3 C 2 T x MXenes. The oxidation of Ti 3 C 2 T x was observed in all the media used in this study, but it is fastest in liquid media and slowest in solid media (including polymer matrices). We also show that the conventional indicators of MXene oxidation, such as changes in color and colloidal stability, are not always reliable. Finally, we demonstrate the acceleration of oxidation under exposure to UV light.

In this study, we successfully demonstrate the electrochemical etching of Al from porous Ti2AlC electrodes in dilute hydrochloric acid to form a layer of Ti2CTx MXene on Ti2AlC.