Reaction mechanism of core–shell MoO2/MoS2nanoflakes via plasma-assisted sulfurization of MoO3
Year: 2016
Type: article
Abstract: The sulfurization of MoO 3 in an H 2 S/Ar plasma atmosphere has been experimentally studied and a reaction mechanism has been proposed based on the results obtained. Nanostructured thin films (NTFs) of MoO 3 were sulfurized at different temperatures varying from 150 °C to 550 °C. High-resolution transmission electron microscopy (TEM) images depict core–shell nanoflakes with varying shell thicknesses as the sulfurization temperature ( T sn ) is varied. The shells consist of MoS 2 and the core is MoO 2 /MoO 3 . X-ray diffraction (XRD) and Raman analysis have been used to study the structural changes as MoO 3 is sulfurized. The analyses showed two phases, MoO 2 and MoS 2 , at low temperatures (≤350 °C), whereas the films sulfurized at higher temperatures show predominantly MoS 2 . The scanning electron microscopy (SEM) results show no noticeable changes in the surface morphology of the NTFs after sulfurization. X-ray photoelectron spectroscopy (XPS) was carried out to calculate the relative percentages of MoO 3 , MoO 2 and MoS 2 . It is revealed that sulfurization of MoO 3 in the plasma is affected by T sn . The sulfurization process occurs in two steps, involving the reduction of MoO 3 to form MoO 2 in the first step, followed by MoO 2 being converted into MoS 2 . It is also evident that the reduction of MoO 3 is more a result of the reactive species of hydrogen (H*) than the replacement of oxygen by sulfur in the second step.
Source: Materials Research Express
Institution: Indian Institute of Technology Delhi
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2408294530