Ultralong Stability of Ti 3 C 2 T x -MXene Dispersion Through Synergistic Regulation of Storage Environment and Defect Capping with Tris-HCl Buffering.

Aqueous MXene dispersion suffers from a bottleneck issue of oxidation, leading to its gradual deterioration and ultimately compromised physicochemical characteristics. Herein, Tris-HCl buffer is employed to stabilize the diluted Ti 3 C 2 T x -MXene dispersion (0.05 mg mL -1 ) through the synergy of its potent pH-regulation capability and capping effect toward oxidation-susceptible defects/edges. Tris-HCl functionalized Ti 3 C 2 T x maintained its original morphology, structure, and favorable dispersity even after 150 days of aging under naturally aerated conditions. The pH-regulation nature of Tris-HCl is elucidated through solution monitoring of Ti 3 C 2 T x dispersion, while the adsorption of Tris-HCl onto defects/edges is revealed by spectral analysis and multi-scale simulations. Tris-HCl at the neutral pH can bind to the negatively charged basal plane of Ti 3 C 2 T x via + HTris moiety, while the other moiety (Tris) interacts with the exposed edge-based Ti atoms and/or intrinsic defects, forming a Ti─N bond that prevents MXene from attack by H 2 O and O 2 . Besides, Tris-HCl stabilized Ti 3 C 2 T x exhibited nearly identical capacitive characteristics to its freshly-etched counterpart, indicating the minimal impact of Tris-HCl on electrochemical performance of Ti 3 C 2 T x during long-term storage. This study provides practical guidance for stabilizing MXene in their native aqueous dispersion without compromising the inherent properties.