The MoS₂ nanotubes with defect-controlled electric properties

We describe a two-step synthesis of pure multiwall MoS₂ nanotubes with a high degree of homogeneity in size. The Mo₆S₄I₆ nanowires grown directly from elements under temperature gradient conditions in hedgehog-like assemblies were used as precursor material. Transformation in argon-H₂S/H₂ mixture leads to the MoS₂ nanotubes still grouped in hedgehog-like morphology. The described method enables a large scale production of MoS₂ nanotubes and their size control. X-ray diffraction, optical absorption and Raman spectroscopy, scanning electron microscopy with wave dispersive analysis, and transmission electron microscopy were used to characterize the starting Mo₆S₄I₆ nanowires and the MoS₂ nanotubes. The unit cell parameters of the Mo₆S₄I₆ phase are proposed. Blue shift in optical absorbance and metallic behaviour of MoS₂ nanotubes in two-probe measurement are explained by a high defect concentration.