Abstract
Two-dimensional (2D) transition metal dichalcogenides (TMDs) have been widely used from nanodevices to energy harvesting/storage because of their tunable physical and chemical properties. In this work, we systematically investigate the effects of hydrogenation on the structural, electronic, magnetic, and catalytic properties of 33 TMDs based on first-principles calculations. We find that the stable phases of TMD monolayers can transit from 1T to 2H phase or vice versa upon the hydrogenation. We show that the hydrogenation can switch their magnetic and electronic states accompanying with the phase transition. The hydrogenation can tune the magnetic states of TMDs among non-, ferro, para-, and antiferro-magnetism and their electronic states among semiconductor, metal, and half-metal. We further show that, out of 33 TMD monolayers, 2H-TiS2 has impressive catalytic ability comparable to Pt in hydrogen evolution reaction in a wide range of hydrogen coverages. Our findings would shed the light on the multi-functional applications of TMDs.
Highlights
Transition, it may result in a lot of defects in the monolayers
We find that 1T and 2H phases can transform to each other upon hydrogenation, depending on the transition metal elements in MX2 monolayers
1T-MX2 (M in group IV) monolayers transfer into 2H phase upon hydrogenation, their ground states can be tuned from non-magnetic to ferromagnetic accompanying with electronic switching from semiconducting to half-metallic
Summary
Transition, it may result in a lot of defects in the monolayers. We present a general method – hydrogenation – to realize the phase transition and tune the physical and chemical properties of 33 different MX2 monolayers. We find that 1T and 2H phases can transform to each other upon hydrogenation, depending on the transition metal elements in MX2 monolayers. Accompanying with the phase transition, their electronic properties switch among semiconducting, metallic, and half metallic, and magnetic ground states among nonmagnetic, ferromagnetic, paramagnetic and anti-ferromagnetic states. We further predict that TiS2 monolayer in 2H phase shows effective catalytic performance for hydrogen evolution reaction in a wide range of hydrogen coverages with neutral thermal Gibbs free energies
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