Superconductivity Modulated by Carbonization and Hydrogenation in Two-Dimensional MXenes M N-2 (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 Mo2N 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-M2N (M = Mo, W) based on first-principles calculations. The results show that the 1T-M2N and 2H-M2N (M = Mo, W) are all dynamically and thermodynamically stable after carbonization and further hydrogenation. After carbonization, Tc's of 1T-M2NC2 (M = Mo, W) are all increased, while T-c's of 2H-M2NC2 (M = Mo, W) are all decreased. By further hydrogenation, the Tc's of 1T-and 2H-M2NC2H2 are all increased. Among all of these structures, Tc of 1T-Mo2NC2H2 is the highest one, reaching 42.7 K, and the corresponding electron-phonon coupling strength ? is 2.27. Therefore, hydrogenation is an effective method to modulate T-c's of 2D M2NC2 (M = Mo, W) materials.