Two-step synthesis of MoS₂ nanotubes using shock waves with lead as growth promoter

A new two-step procedure for the synthesis of MoS₂ nanotubes using lead as a growth promoter is reported. In the first step, molybdenum suboxide nanowhiskers containing a small amount of lead atoms were created by exposing a pressed MoS₂+Pb mixture to highly compressed shock-heated argon gas, with estimated temperatures exceeding 9900 K. In the second step, these molybdenum suboxide nanowhiskers served as templates for the sulfidization of the oxide into MoS₂ nanotubes (by using H₂S gas in a reducing atmosphere at 820 °C). Unlike the case of WS₂ nanotubes, the synthesis of a pure phase of MoS₂ nanotubes from molybdenum oxide has proven challenging, due mostly to the volatile nature of the latter at the high requisite reaction temperatures (>800 °C). In contrast, the nature and apparent reaction mechanism of the method reported herein are amenable to future scale-up. The high-temperature shockwave system should also facilitate the synthesis of new nanostructures from other layered materials.