Gold Decoration and Photoresistive Response to Nitrogen Dioxide of WS₂ Nanotubes

Composites of WS₂ nanotubes (NT‐WS₂) and gold nanoparticles (AuNPs) were prepared using aqueous HAuCl₄ solutions and subjected to surface analysis. The obtained materials were jointly characterized by X‐ray photoelectron (XPS), Raman scattering (RSS), and ultraviolet photoelectron (UPS) spectroscopies. Optical extinction spectroscopy and electron energy loss spectroscopy in the scanning transmission electron microscopy regime (STEM‐EELS) were also employed to study plasmon features of the nanocomposite. It was found that AuNPs deposition is accompanied by a partial oxidative dissolution of WS₂, whereas Au‐S interfacial species could be responsible for the tight contact of metal nanoparticles and the disulfide. A remarkable sensitivity of n‐type resistance of NT‐WS₂ and Au‐NT‐WS₂ to the adsorption of NO₂ gas was also demonstrated at room temperature using periodical illumination by a 530 nm light‐emitting diode. Au‐NT‐WS₂ nanocomposites are found to possess a higher photoresponse and enhanced sensitivity in the 0.25–2.0 ppm range of NO₂ concentration, as compared to the pristine NT‐WS₂. This behaviour is discussed within the physisorption‐charge transfer model to explore sensing properties of the nanocomposites.