Rational control on the morphology of WS2 nanomaterials by altering hydrothermal reaction conditions

Here, we present the synthesis of nanomaterials based on WS2, using a simple and green hydrothermal route. The synthesis was accomplished by the high-temperature hydrothermal reaction of WS2 powder in aqueous NaOH. Upon changing the mole ratio of WS2 to NaOH, different types of nanomaterials such as quantum dots (QDs), nanosheets and hybrid QDs-nanosheets were obtained. We systematically characterized the optical properties of these materials. All exhibited high photoluminescence spanning a large portion of the UV and visible region of the electromagnetic spectrum. The morphological and other structural aspects were unraveled by transmission electron microscopy (TEM) and Raman spectroscopy. Size-dependent photophysical properties of various WS2 nanomaterials were investigated using UV–visible absorption spectroscopy, fluorescent spectroscopy and fluorescence lifetime analysis. We envisage that these materials can be promising candidates for various biological and optoelectronic applications due to their extraordinary temporal and photostability.