Unveiling the influence of various vacancies on the mechanical properties of Ti 4 C 3 O 2

Two-dimensional transition metal carbides and nitrides are widely recognized as potential candidates in areas such as energy storage and sensors. In this work, we explore the mechanical properties of Ti 4 C 3 O 2 with a perfect cell and Ti 4 C 3 O 2 with vacancies by a first-principles method. The results indicate that the loss of C in the outer layer of Ti 4 C 3 O 2 is more likely to occur due to the smaller formation energy of C-vacancy. By considering the charge contribution, the removed atom changes the valence electron equilibrium concentration between that atom and its neighbors, which in turn affects the mechanical properties of Ti 4 C 3 O 2 . The presence of various vacancies affects the strength of the Ti - O bonds on the shear plane, causing Ti 4 C 3 O 2 to exhibit changes towards brittleness or ductility. It is noteworthy that the elastic modulus, critical strain, and ideal stress of Ti 4 C 3 O 2 with different concentrations of O vacancies are all approximately the same, suggesting that the variations in their mechanical properties are not significant for Ti 4 C 3 O 2 with different degrees of O functional group coverage. Our findings offer valuable insights for the development of MXene-based nanoflexible energy storage devices, gassensitive sensors, high-temperature environmental applications, and beyond.