Low-Temperature Solution Synthesis of Few-Layer 1T′-MoTe₂ Nanostructures Exhibiting Lattice Compression

Molybdenum ditelluride, MoTe₂, is emerging as an important transition-metal dichalcogenide (TMD) material because of its favorable properties relative to other TMDs. The 1T′ polymorph of MoTe₂ is particularly interesting because it is semimetallic with bands that overlap near the Fermi level, but semiconducting 2H-MoTe₂ is more stable and therefore more accessible synthetically. Metastable 1T′-MoTe₂ forms directly in solution at 300%deg;C as uniform colloidal nanostructures that consist of few-layer nanosheets, which appear to exhibit an approx. 1% lateral lattice compression relative to the bulk analogue. Density functional theory calculations suggest that small grain sizes and polycrystallinity stabilize the 1T′ phase in the MoTe₂ nanostructures and suppress its transformation back to the more stable 2H polymorph through grain boundary pinning. Raman spectra of the 1T′-MoTe₂ nanostructures exhibit a laser energy dependence, which could be caused by electronic transitions.