Few-layer thick WS2 nanosheets produced by intercalation/exfoliation route

Thin two-dimensional (2D) nanostructures of layered materials are of importance for both science and technology due to their unique properties and promising applications. Few-layer tungsten disulfide (WS2) presents some amazing optoelectronic behaviors that have attracted great interest. In this work, WS2 nanosheets with few-layer (< 10 layers) thickness have been successfully produced by Li ions intercalation/exfoliation of bulk WS2 via a solvothermal technique. X-ray diffraction indicates that hexagonal crystal structure of bulk WS2 remains the same after the intercalation/exfoliation treatment. Scanning electron microscopy and transmission electron microscopy characterizations reveal that the exfoliated products are single-crystalline thin nanosheets with high crystallinity. Atomic force microscopy reveals that 8-layer thick WS2 nanosheets can be fabricated by the present approach. Raman phonon modes of the prepared WS2 nanosheets present the redshifts due to their decreased thickness. The work provides a facile and affective route to high-quality WS2 thin 2D nanostructures that would have great potentials for optoelectronics.