MXenes, as attractive two-dimensional materials, have shown extraordinary potential for applications, however, their instability severely limits further research and applications on a large-scale and industrial level. Here, we overcome the environmental instability of MXene-Ti₃C₂T_x by an optimized synthetic route, including the synthesis of high-quality MAX phase (Ti₃AlC₂) and the post-treatment of Ti₃C₂T_x. The optimized Ti₃C₂T_x (O-Ti₃C₂T_x) achieves a dramatic improvement in stability. Even at low concentrations (∼0.1 mg/mL), the dark green aqueous dispersion of monolayer O-Ti₃C₂T_x showed no oxidation and degradation when aged under ambient conditions for two months, while conventional Ti₃C₂T_x required only ∼10 days for complete oxidative degradation under the same conditions. More importantly, compared with the conventional Ti₃C₂T_x, O-Ti₃C₂T_x exhibits higher conductivity, better nonlinear optical properties, excellent thermal stability, and comparable biocompatibility. In the application of pulsed laser with MXene as a saturable absorber, the conventional Ti₃C₂T_x leads to severe degradation of Q-switching performance due to its instability, while O-Ti₃C₂T_x shows excellent Q-switching performance in long-term operation. This work achieves a substantial solution to the instability problem of MXene-Ti₃C₂T_x without compromising its excellent performance, paving the way for the development of its practical applications.

MXenes作为极具吸引力的二维材料，展现出非凡的应用潜力，然而，其不稳定性严重限制了进一步的大规模和工业级研究和应用。在这里，我们通过优化的合成路线克服了 MXene-Ti ₃ C ₂ T _x的环境不稳定性，包括高质量 MAX 相（Ti ₃ AlC ₂）的合成和 Ti ₃ C ₂ T _x的后处理。优化的 Ti ₃ C ₂ T _x (O-Ti ₃ C ₂ T _x) 实现了稳定性的显着提高。即使在低浓度（~0.1 mg/mL）下，单层 O-Ti ₃ C ₂ T _x的深绿色水性分散体在环境条件下老化两个月后也没有氧化和降解，而传统的 Ti ₃ C ₂ T _x则需要在相同条件下仅需约 10 天即可完全氧化降解。更重要的是，与传统的Ti ₃ C ₂ T _x相比，O-Ti ₃ C ₂ T _x表现出更高的电导率、更好的非线性光学特性、优异的热稳定性和相当的生物相容性。在以MXene作为可饱和吸收体的脉冲激光应用中，传统的Ti ₃ C ₂ T _x由于其不稳定导致Q开关性能严重下降，而O-Ti ₃ C ₂ T _x表现出优异的Q开关性能在长期经营中。这项工作在不影响其优异性能的情况下，实质性地解决了MXene-Ti ₃ C ₂ T _x的不稳定问题，为其实际应用的发展铺平了道路。