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

Abstract

Due to the high conductivity and abundant active sites, the metallic 1T phase of a two-dimensional molybdenum sulfide monolayer (1T-MoS₂) has witnessed a broad range of potential applications in catalysis, and spintronic and phase-switching devices, which, however, are greatly hampered by its poor stability. Thus, the development of particular strategies to realize the phase transition from the stable 2H phase to the metastable 1T phase for MoS₂ nanosheets is highly desirable. Herein, by means of density functional theory (DFT) computations, we systematically explored the potential of the interfacial interaction of 2H- and 1T-MoS₂ monolayers with a series of M₂C MXenes (M = Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W) for achieving the 2H/1T phase transformation. Our results revealed that the 2H → 1T transition for MoS₂ monolayers can occur thermodynamically by anchoring on Ti₂C, Zr₂C, or Hf₂C substrates with the extremely strong metal-S interaction, which can be well rationalized by the analysis of the charge transfer, work function, and density of states. Specially, these obtained stable 1T-MoS₂/M₂C hybrid materials exhibit excellent metallic features, outstanding magnetism, and enhanced mechanical properties. Our findings provide a new avenue to tune the phase transformation for MoS₂ monolayers by strong interfacial interactions, which helps to further widen the potential applications of MoS₂ monolayers.