Solvation structure design for stabilizing MXene in transition metal ion solutions

Although MXene has attracted great interest in diverse fields, it is susceptible to oxidation in water (H2O) with transition metal ions such as Co2+, Fe2+, and Cu2+, which is pronounced at high temperatures. This impedes the preparation of MXene‐based composites and their functional applications. Here, this study revealed that Co2+ increases the maximum and average atomic charge of H in H2O to improve the reactivity of H2O, which leads to the fact that Co2+ catalyzes the oxidation of Ti3C2Tx MXene. Furthermore, the addition of N,N‐dimethyl formamide (DMF) reduces the H2O activity and improves the oxidation stability of Ti3C2Tx in the presence of Co2+ via preferentially forming coordination bonds with Co2+. This strategy is also effective in enhancing the oxidation tolerance of Ti3C2Tx to Fe2+ in H2O. Moreover, it is feasible to enhance the oxidation stability of Ti2CTx MXene in H2O with the existence of Co2+. By virtue of these, the CoO/Ti3C2Tx composite was successfully prepared without obvious Ti3C2Tx oxidation, which is desirable to harness the advantages of Ti3C2Tx as the complementary component for lithium‐ion batteries. This work provides a straightforward paradigm to enhance the oxidation resistance of MXene in H2O in the presence of transition metal ions and at high temperatures, which opens a new vista to use MXene for target applications.