Realization of hydrogenation-induced superconductivity in two-dimensional Ti 2 N MXene.

Two-dimensional (2D) MXene superconductors have been currently attracting considerable interest due to their unique electronic properties and diverse applicability. Utilizing first-principles computational methods, we have designed two distinct configurations of hydrogenated 2D Ti 2 N MXene materials, namely Ti 2 NH 2 and Ti 2 NH 4 , and have conducted an exhaustive analysis of their structural stability, electronic characteristics, and superconductivity. Hydrogenation endows monolayer Ti 2 N with inherent metallic characteristics, as evidenced by an elevated density of states (DOS) at the Fermi level ( E f ). Notably, Ti 2 NH 4 exhibits a superconducting critical temperature ( T c ) of 15.8 K, which is predominantly ascribed to the electronic contributions stemming from the Ti 3d orbitals. Analysis of phonon dispersion underscores the pivotal role that diverse lattice vibrational modes play in electron-phonon coupling (EPC), particularly the significance of low-frequency vibrations for facilitating electron pairing and the emergence of superconductivity. Furthermore, strain engineering can effectively modulate the superconducting properties of Ti 2 NH 4 , with a 2% tensile strain enhancing the EPC strength ( λ ) to 0.857 and increasing T c to 18.7 K. This research elucidates the superconducting mechanisms of hydrogenated Ti 2 N structures, offering valuable insights for the development of novel 2D superconducting materials.