Oxidation Stability of Colloidal Two-Dimensional Titanium Carbides (MXenes)

Two-dimensional (2D) transition metal carbides and nitrides (MXenes) have shown outstanding performances in electrochemical energy storage and many other applications. Delamination of MXene flakes in water produces colloidal solutions that are used to manufacture all kinds of products (thin films, coatings, and electrodes, etc.). However, the stability of MXene colloidal solutions, which is of critical importance to their application, remains largely unexplored. Here we report on the degradation of delaminated-Ti3C2Tx colloidal solutions (T represents the surface functionalities) and outline protocols to improve their stability. Ti3C2Tx MXene solutions in open vials degraded by 42%, 85%, and 100% after 5, 10, and 15 days, respectively, leading to the formation of cloudy-white colloidal solutionss containing primarily anatase (TiO2). On the other hand, the solution could be well-preserved when Ti3C2Tx MXene colloidal solutionss were stored in hermetic Ar-filled bottles at 5 °C, because dissolved oxygen, th...