Two-in-one strategy to enhance the stability of Ti₃C₂T_x in transition metal ion solutions

Although MXenes have attracted significant attention across diverse fields, they exhibit a pronounced susceptibility to oxidation in aqueous environments, with oxidation significantly accelerated in the presence of transition metal ions (TMI) such as Fe³⁺ and Cu²⁺. This limitation impedes the synthesis of transition metal compounds/MXene-based composites and their potential for functional applications. In this study, we elucidate the mechanism of accelerated oxidation of Ti₃C₂T_x is that Fe³⁺ promotes the electron loss in Ti₃C₂T_x, thus leading to an increased production of hydroxyl radicals (OH) to oxidize Ti₃C₂T_x. Furthermore, a rational two-in-one strategy is provided with adding electron-rich ethylenediaminetetraacetic acid disodium zinc salt (ZnNa₂EDTA) to enhance the stability of Ti₃C₂T_x by defect filling and electron donation. Consequently, the production of OH is significantly reduced and thus Ti₃C₂T_x remains well-preserved in the presence of Fe³⁺, which has also effectively enhanced the oxidation stability of Ti₃C₂T_x in the presence of Cu²⁺. This work is expected to pave a new pathway for targeted applications with coexisting Ti₃C₂T_x and TMI.