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

Abstract

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-M 2N (M = Mo, W) based on first-principles calculations. The results show that the 1T-M 2N and 2H-M 2N (M = Mo, W) are all dynamically and thermodynamically stable after carbonization and further hydrogenation. After carbonization, T c’s of 1T-M 2NC2 (M = Mo, W) are all increased, while T c’s of 2H-M 2NC2 (M = Mo, W) are all decreased. By further hydrogenation, the T c’s of 1T- and 2H-M 2NC2H2 are all increased. Among all of these structures, T c of 1T-Mo2NC2H2 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 2NC2 (M = Mo, W) materials.