Superconductivity Modulated by Carbonization and Hydrogenation in Two-Dimensional MXenes M 2N (M = Mo, W)

The superconductivity of two-dimensional (2D) materials has extremely important research significance. To date, superconducting transition temperatures ( T c ) of 2D superconductors are still far from practical applications. Previously, 2D MXene Mo 2 N has been successfully synthesized [Urbankowski et al. Nanoscale 9 17722, (2017)]. We systematically investigate the effects of carbonization and further hydrogenation on the stability, electronic property and superconductivity of 1T- and 2H- M 2 N ( M = Mo, W) based on first-principles calculations. The results show that the 1T- M 2 N and 2H- M 2 N ( M = Mo, W) are all dynamically and thermodynamically stable after carbonization and further hydrogenation. After carbonization, T c ’s of 1T- M 2 NC 2 ( M = Mo, W) are all increased, while T c ’s of 2H- M 2 NC 2 ( M = Mo, W) are all decreased. By further hydrogenation, the T c ’s of 1T- and 2H- M 2 NC 2 H 2 are all increased. Among all of these structures, T c of 1T-Mo 2 NC 2 H 2 is the highest one, reaching 42.7 K, and the corresponding electron-phonon coupling strength λ is 2.27. Therefore, hydrogenation is an effective method to modulate T c ’s of 2D M 2 NC 2 ( M = Mo, W) materials.