Hydrogenation-induced high-temperature superconductivity in two-dimensional molybdenum carbide Mo₂C₃

¹ School of Physics and Physical Engineering, Qufu Normal University - Qufu 273165, China
² Institute of Applied Physics and Computational Mathematics - Beijing 100088, China

^(a) hylu@qfnu.edu.cn (corresponding author)
^(b) pzhang2012@qq.com

Received: 25 February 2022
Accepted: 9 May 2022

Abstract

Two-dimensional (2D) superconductors have important potential applications in constructing nano superconducting devices, thus, 2D superconductors with high critical temperature (T_c) are highly desired. Till now, the T_c of 2D superconductors are still relatively low. Based on density functional first-principles calculations, we predicted a new stable 2D transition metal molybdenum carbide 2H-Mo₂C₃. Based on the Eliashberg theory, we predict that it is not a superconductor. However, after hydrogenation, the hydrogen atoms increase the electronic density of states at the Fermi level, and strengthen the electron-phonon coupling. Accordingly, the hydrogenated 2H-Mo₂C₃, i.e., 2H-Mo₂C₃H₂, is a 2D superconductor with T_c of 53 K, exceeding the McMillan limit. Thus, hydrogenation is an important strategy for obtaining 2D high-temperature superconductors at atmosphere pressure. In view of the high superconducting T_c of 2H-Mo₂C₃H₂, it is highly expected to be synthesized in future experiments.