Superconductivity in the Janus WSH Monolayer.

Hydrogen-based compounds have been found to exhibit high superconducting critical temperature ( T c ) through the electron–phonon coupling mechanism under ultrahigh pressure. Herein, a new two-dimensional transition metal dichalcogenide material is constructed, namely, the Janus WSH monolayer. It is formed by replacing one layer of S atoms in the WS₂ monolayer with H atoms. Then the electronic structure, phonon dispersion, electron–phonon coupling, and superconductivity are investigated by first-principles calculations. The results show that the introduction of H atoms helps to flatten the electronic dispersion and leads to high electronic density of states at the Fermi level, resulting in strong electron–phonon coupling. Additionally, the softening of phonon modes from the hybridization of in-plane W atomic vibrations and out-of-plane H atomic vibrations boosts the electron–phonon coupling further. The strong interactions between electrons and phonons lead to phonon-mediated superconductivity in Janus WSH monolayer with a calculated T c being about 23.1 K. This is the highest T c predicted in WS₂-based materials at present, which indicates that hydrogenation is a great way to improve the T c of transition metal dichalcogenide materials. [ABSTRACT FROM AUTHOR]