New quantum spin Hall insulator in two-dimensional MoS2 with periodically distributed pores

Area of Science:

• Materials Science
• Condensed Matter Physics
• Computational Chemistry

Background:

• Molybdenum disulfide (MoS2) is a transition metal dichalcogenide (TMD) with notable semiconductor properties.
• TMDs are extensively researched for their electronic and catalytic applications.

Purpose of the Study:

• To predict and characterize a novel 2D Quantum Spin Hall (QSH) insulator phase in a porous allotrope of monolayer MoS2 (g-MoS2).
• To investigate the electronic band structure and stability of this new g-MoS2 polymorph.
• To explore potential applications arising from its unique structure and electronic properties.

Main Methods:

• Density Functional Theory (DFT) calculations were employed to predict the electronic and structural properties of g-MoS2.
• Phonon spectrum analysis was used to confirm the stability of the predicted g-MoS2 structure.

Main Results:

• A novel 2D Quantum Spin Hall (QSH) insulator phase, g-MoS2, was predicted, featuring a porous structure of MoS2 squares and hexagons.
• g-MoS2 exhibits a nontrivial band gap of 109 meV, attributed to a unique d-d band inversion mechanism.
• Phonon spectrum analysis confirmed the stability of the g-MoS2 polymorph.
• The porous structure suggests potential for gas separation and energy storage applications.

Conclusions:

• The discovery of g-MoS2 expands the family of 2D materials and TMDs.
• The unique d-d band inversion in g-MoS2 offers a new mechanism for achieving QSH effects.
• The predicted g-MoS2 material holds promise for advanced applications in gas separation and energy storage due to its porous nature and electronic properties.