Thin WS₂ nanotubes from W₁₈O₄₉ nanowires

Abstract

Single-and double-walled WS 2 nanotubes of small diameter (<10 nm) and few layers (<4) have been synthesized by heating ultrathin W 18 O 49 nanowires and S powders in an H 2 /Ar atmosphere at 840°C. In the process of formation and growth of a WS 2 nanotube, the W 18 O 49 phase transformed first into an amorphous WS 3 structure via the absorption and diffusion of the sulfur atoms to substitute the oxygen atoms, and followed by a phase transition from amorphous WS 3 to 2H-WS 2 by losing sulfur atoms to form the shell of the WS 2 nanotube. IMPACT STATEMENTSynthesis of thin WS 2 nanotubes with single-and doubled-walled structure from ultrathin W 18 O 49 nanowires is developed and their structure and growth are studied using electron diffraction and microscopy. ARTICLE HISTORY

Hydrothermal synthesis and controlled growth of group-VIB W metal compound nanostructures from tungsten oxide to tungsten disulphide

“…In this process, the H atoms play an important role, which has the effect of reducing WO 3 . In addition, Y. H. Chen et al 24 reported another role of the H atom when the precursor is W 18 O 49 , which prevents the oxidation of W 18 O 49 and enhances the effect of the subsequent vulcanization process. A. J. van der Vlies et al 48 reported that S is allowed to enter WO 3 when ∼20% of the tungsten centers were reduced from 6 + to 5 + .…”

“…1(a)), 21–23 WS 2 is fabricated by sulfiding tungsten oxide (in the lower left corner of Fig. 1(a)), 24–28 and the WS x O y hybrid (such as S-doped WO 3 , O-doped WS 2 and WO 3 /WS 2 heterojunction) is present in the process. 29–31 Fig.…”

“…Researchers usually flow H 2 S gas through W powder or W oxide (including WO 3 , WO 2.92 , WO 2.9 and WO 2.72 ) at high temperature for the sulfidation reaction by CVD method. 24–27 It is easier to reduce W 6+ to W 5+ with the assistance of Ar/H 2 , but the sulfurization reaction can occur at the lowest temperature of 400 °C. 34 Several common vulcanization routes are summarized in the center of Fig.…”

Layered tungsten-based composites and their pseudocapacitive and electrocatalytic performance

“…The phase transformation of W 18 O 49 is expected to initially proceed through the formation of WS 3 via the substitution of oxygen atoms with sulphur atoms. 15 Further reaction leads to the formation of WS 2 with residual orthorhombic WO 3 nanoparticles due to oxidation occurring during sulfidation. The presence and homogeneous distribution of C, N, W, O and S was clearly confirmed from the elemental mapping of WS_800 (Fig.…”

Open-ended W18O49-filled tungsten dichalcogenide nanotubes grown on a W substrate to efficiently catalyze hydrogen evolution

“…Tungsten dichalcogenides nanotubes had been introduced into the family of inorganic nanotubes for many years, and the sulfurization/selenization of tungsten oxide nanowires, a template technique developed by Tenne and Zhu et al, 18,19 has been widely studied to form their tubular nanostructures. [20][21][22][23] However, unlike what achieved in the research of carbon nanotubes, to grow WSe 2 /WS 2 nanotube arrays over large area still remains challenging. In this communication, we will report a scalable one-step CVD method to directly grow denselypacked aligned WOx-filled WSe 2 nanotubes or WS 2 nanotubes, and importantly, employing a simple growth control can keep nanotubes universally uncapped at the top-ends, which would greatly boost the density active edge sites on tubular nanostructures.…”