Annealed Ti₃C₂T_z MXene Films for Oxidation-Resistant Functional Coatings

Two-dimensional transition metal carbide and nitride nanomaterials, known as MXenes, exhibit low chemical stability in aqueous environments; they tend to oxidize and react with water molecules, resulting in structural degradation and decreased electrical conductivity. This significantly limits their storage lifetime and potential use in the presence of water, particularly in nanosheet-assembled films for battery electrodes and functional coatings. Here we demonstrate that thermal annealing of Ti3C2Tz films at elevated temperatures (∼600 °C) causes changes in the termination distribution as well as the formation of a protective layer of TiO2 on the outermost layer of films. The induced chemical and structural changes during thermal treatment arrest MXene oxidation and enable the MXene films to be stable in aqueous solutions for over 10 months.