How to Prepare WS2 Nanotube with W18O49 Nanowire?

Under an atmosphere of H₂ or Ar, WS₂ nanotube with small diameter and few layers can be successfully synthesized by heating W₁₈O₄₉ nanowire and sulfur powders at 840°C. During the preparation process, W₁₈O₄₉ nanowire is first prepared from WCl₆ and ethanol.

At present, WS₂ nanotube is usually prepared by gas-solid phase synthesis. However, the obtained WS₂ nanotube often has large diameter and always has more than five layers, resulting in a low-specific surface area. In this point, the synthesis of WS₂ nanotube with small diameter (<10 nm) and few shells (<4) has been considered a great experimental challenge.

Researchers are trying to find a feasible way to prepare WS₂ nanotube with small diameter and few shells. Here is a specific preparation process as following as:

WS₂ nanotube is obtained in a two-step process. In the first step, W₁₈O₄₉ nanowire is prepared. In a typical procedure, 25 mg of WCl₆ is dissolved in 20 mL of ethanol and subsequently transferred to a teflon-lined stainless steel autoclave heated to 180°C for 24 hours. The obtained solution is then centrifuged and purified with ethanol for five times before the precipitates are collected.

In the second step, 2 mg of W₁₈O₄₉ nanowire is first dispersed in 10 mL of ethanol. A quartz burette is then dipped into the ethanol solution to collect the W₁₈O₄₉ nanowire for reaction with sulfur powders at 840°C in a furnace for 3 hours, so as to allow the formation and growth of WS₂ nanotube.

During the preparation process, W₁₈O₄₉ nanowire is prepared by solvothermal method. It is directly used as the template for the formation and growth of WS₂ nanotube, which is the main advantage of this kind of preparation method. Since the W₁₈O₄₉ phase is non-volatile, the produced WS₂ nanotube would retain the morphology of its template and a diameter below 10 nm would be reachable.

W₁₈O₄₉ nanowire is reduced by sulfur powders in the reducing atmosphere of H₂ or Ar, so as to prepare WS₂ nanotube successfully.

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