Fig. 2

TEM images of a MXene flakes from fresh d-Ti₃C₂T_x solution and aged solutions in open air for c 7 days and e 30 days, respectively. b, d, f The high-resolution TEM images of a, c, e; respectively. Inset in b is the corresponding Selected Area Electron Diffraction (SAED) pattern, and those in d, f are the corresponding FFT patterns. g, h Photographs of fresh Ti₃C₂T_x MXene in water, and the aged Ti₃C₂T_x MXene dispersion in water after 30 days in open air, showing an opaque whitish color due to oxidation. i UV–visible absorbance spectra of pristine Ti₃C₂T_x in water collected over a period of one month. a–f Reproduced with permissions from ref. [41]. Copyright (2017), American Chemical Society. g–i Reproduced with permissions from ref. [40]. Copyright (2019), American Chemical Society