Enhancing superconductivity in MXenes through hydrogenation

Two-dimensional transition metal carbides and nitrides (MXenes) are an emerging class of atomically-thin superconductors, whose characteristics are highly prone to tailoring by surface functionalization. Here we explore the use of hydrogen adatoms to enhance phonon-mediated superconductivity in MXen...

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Bibliographic Details
Published in:Nanoscale 2022-07, Vol.14 (27), p.9918-9924
Main Authors: Bekaert, Jonas, Sevik, Cem, Miloševi, Milorad V
Format: Article
Language:English
Subjects:
Adatoms
Charge transfer
First principles
Metal carbides
MXenes
Niobium carbide
Phonons
Structural models
Structural stability
Superconductivity
Superconductors
Transition metals
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Summary:Two-dimensional transition metal carbides and nitrides (MXenes) are an emerging class of atomically-thin superconductors, whose characteristics are highly prone to tailoring by surface functionalization. Here we explore the use of hydrogen adatoms to enhance phonon-mediated superconductivity in MXenes, based on first-principles calculations combined with Eliashberg theory. We first demonstrate the stability of three different structural models of hydrogenated Mo- and W-based MXenes. Particularly high critical temperatures of over 30 K are obtained for hydrogenated Mo 2 N and W 2 N. Several mechanisms responsible for the enhanced electron-phonon coupling are uncovered, namely (i) hydrogen-induced changes in the phonon spectrum of the host MXene, (ii) emerging hydrogen-based phonon modes, and (iii) charge transfer from hydrogen to the MXene layer, boosting the density of states at the Fermi level. Finally, we demonstrate that hydrogen adatoms are moreover able to induce superconductivity in MXenes that are not superconducting in pristine form, such as Nb 2 C. We reveal that superconductivity in MXenes, 2D crystals of transition metal carbides and nitrides, is strongly enhanced by surface functionalization with hydrogen. Elevated superconducting transition temperatures of up to 32 K are achieved.
ISSN:2040-3364
2040-3372
DOI:10.1039/d2nr01939f