A review of how to improve Ti3C2Tx MXene stability

Recently, the two-dimensional (2D) Ti3C2Tx (MXene) has attracted more and more attentions in energy, electronics, environment, biomedicine, etc., due to its unique features such as high conductivity, unusual layered structures, adjustable surface chemistry, and outstanding mechanical properties. However, the easy degradation of MXene in the presence of oxygen and moisture would induce the destruction of its microstructures and thus affect the physical and chemical properties of MXene, resulting in minimal practical applications of MXene-based functional devices. To this end, increasing efforts have been made in the MXene community to improve the environmental stability of MXene, from theories to experiments. It is important to timely summarize the recent progress on the stability of MXene. In this review, firstly, the structures and synthesis of MXenes are briefly introduced. Secondly, the mechanisms of Ti3C2Tx MXene degradation are analyzed from the angles of oxidation and hydrolysis. Thirdly, the effects of MXene degradation on its physical and chemical properties (i.e., electronic, optical, mechanical, and catalytic properties) are carefully discussed, which are often missed in other review articles on MXene stability. Lastly and most importantly, recently reported strategies for effectively inhibiting or slowing down the degradation of MXene are systematically summarized from four aspects of optimizing the MXene preparation process, performing post-treatments on MXene, promoting the storage conditions of MXene, and encapsulation of MXene. This timely review is helpful for preparations, storage, and applications of MXenes in widespread fields.