Controlled 2H/1T phase transition in MoS₂ monolayers by a strong interface with M₂C MXenes: a computational study

Area of Science:

• Materials Science
• Condensed Matter Physics
• Surface Science

Background:

• The metallic 1T phase of molybdenum disulfide (MoS₂) offers high conductivity and active sites for catalysis and spintronics.
• Poor stability of 1T-MoS₂ hinders its practical applications, necessitating strategies for phase transition from the stable 2H phase.

Purpose of the Study:

• To investigate the potential of M₂C MXene substrates in inducing the phase transition of 2D molybdenum disulfide monolayers from the 2H to the 1T phase.
• To explore the interfacial interactions governing this phase transformation and the properties of the resulting hybrid materials.

Main Methods:

• Density Functional Theory (DFT) computations were employed to systematically study the interactions between 2H/1T-MoS₂ monolayers and various M₂C MXenes (M = Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W).
• Analysis of charge transfer, work function, and density of states was used to understand the mechanism of phase transformation.

Main Results:

• Thermodynamic 2H → 1T phase transition of MoS₂ monolayers was achieved by anchoring on Ti₂C, Zr₂C, or Hf₂C substrates due to strong metal-sulfur interactions.
• The resulting 1T-MoS₂/M₂C hybrid materials demonstrated excellent metallic characteristics, significant magnetism, and improved mechanical properties.
• The interfacial interaction strength was correlated with the observed phase transition and material property enhancements.

Conclusions:

• Strong interfacial interactions, particularly with Ti₂C, Zr₂C, and Hf₂C, provide an effective strategy for stabilizing the metastable 1T phase of MoS₂ monolayers.
• This approach offers a new pathway to tune the phase and enhance the properties of MoS₂ for advanced applications in catalysis and electronics.
• The study highlights the role of substrate engineering in controlling the phase and functionality of 2D materials.