Effect of Mechanical Grinding and Sonication on the Optical Properties of MoS2 Nanosheets

In the present study, MoS2 nanosheets are prepared by a two-step, grinding-assisted ultrasonication technique. Various parameters governing the optical, electrical, and dielectric properties of the MoS2 nanosheets are determined from the absorbance, reflectance, and transmittance spectra acquired using UV-Vis spectroscopy. These parameters are analysed with change in grinding hours as well as for sonication effects. It is observed that the absorption coefficient, optical conductivity, and dissipation factor increase (along with a decrease in refractive index) with increase in grinding hours and with sonication. The obtained changes in the optical parameters are correlated with the number of exfoliated layers revealed by Raman spectroscopy. The results of this study provide insightful information about the layer-dependent properties of MoS2 nanosheets and develop better understanding of how the synthesis routes are effective for tailoring the optical response of MoS2 nanosheets.