Ultrasonic preparation of tungsten disulfide single-layers and quantum dots

Abstract

Natural raw mineral tungstenite (WS₂) was exfoliated to single-layer sheets using high intensity ultrasound. Exfoliation of bulk layered materials, such as WS₂ by ultrasound is an attractive way to a large-scale preparation of mono- or few-layered crystals. To evaluate the quality of delamination, X-ray diffraction, Raman spectroscopy and microscopic techniques (TEM and AFM) were employed. The obtained exfoliated product served as a precursor for quantum dot preparation using simple refluxing in ethylene glycol. The synthesized WS₂ quantum dots were characterized by photoluminescence spectroscopy and AFM microscopy. Exfoliated WS₂ can thus join the group of similarly prepared single-layers of MoS₂ or graphene.