Disulfide nanotubes are analogs of the well-known carbon nanotubes (CNTs). However, they have been much less tested in sensing and optoelectronic technologies. The functionalization of disulfide nanotubes is still trickier than for CNTs, and no universal surface activation methods have been found so far.

Alexander Polyakov, Lomonosov Moscow State University, Russia, and colleagues have functionalized WS₂ nanotubes (NT-WS₂) with gold nanoparticles and evaluated the gas-sensing properties of the resulting nanocomposites. Gold nanoislands (pictured) can be grown onto NT-WS₂ by direct interaction of the disulfide with dissolved HAuCl_4.

Due to the plasmonic features of gold nanoparticles, the synthesized material can be easily excited by visible light. The gold-decorated nanotubes (Au–NT–WS₂) have a remarkable sensitivity to NO₂ gas at room temperature under periodical illumination by a 530 nm-light-emitting diode. Au–NT–WS₂ possesses a sensitivity in the 0.25–2.0 ppm range of NO₂ concentration. The material could, thus, be used in low-power sensors to detect toxic NO_x gases.

• Gold Decoration and Photoresistive Response to Nitrogen Dioxide of WS₂ Nanotubes,
  Alexander Yu. Polyakov, Daniil A. Kozlov, Vasily A. Lebedev, Ratibor G. Chumakov, Alexander S. Frolov, Lada V. Yashina, Marina N. Rumyantseva, Eugene A. Goodilin,
  Chem. Eur. J. 2018.
  https://doi.org/10.1002/chem.201803502