Realization of hydrogenation-induced superconductivity in two-dimensional Ti2N MXene

Abstract

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 Ti₂N MXene materials, namely Ti₂NH₂ and Ti₂NH₄, and have conducted an exhaustive analysis of their structural stability, electronic characteristics, and superconductivity. Hydrogenation endows monolayer Ti₂N with inherent metallic characteristics, as evidenced by an elevated density of states (DOS) at the Fermi level (E_f). Notably, Ti₂NH₄ 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 Ti₂NH₄, 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 Ti₂N structures, offering valuable insights for the development of novel 2D superconducting materials.