Core–Shell WO₃–WS₂ Nanostructured Thin Films via Plasma Assisted Sublimation and Sulfurization

The present work describes the synthesis of WO3/WS2 core–shell nanorods (NRs) using plasma assisted sublimation followed by sulfurization process. In this process, WO3 nanostructured thin films were deposited using resistively heated tungsten (W) strip in the presence of O2 plasma and their subsequent sulfurization at different temperatures in the presence of H2S/Ar plasma. The sulfurization temperature (Ts) was varied from 150 to 550 °C in order to obtain the core–shell WO3/WS2 with varying shell thickness. The structural properties of the as-obtained core–shell nanostructures were studied using XRD, Raman spectroscopy, XPS, and morphological properties using SEM, HR-TEM. It is observed that an intermediate oxidation state (5+) of W is formed during the conversion of WO3 (6+) into WS2 (4+). The use of plasma reduced the energy barrier required for sulfurization. The mechanism for sulfurization of WO3 NRs in the presence of reactive species of H2S/Ar plasma is also proposed.