Hydrothermal and template-free preparation and characterization of nanocrystalline ZnS in presence of a low-cost ionic liquid and photocatalytic activity

Low temperature, template-free and hydrothermal method is proposed for preparation of nanocrystalline ZnS in presence of 1-ethyl-3-methylimidazolium ethyl sulfate, [EMIM][EtSO4], room-temperature ionic liquid (RTIL). The powder X-ray diffraction (XRD) studies display that the products are excellently crystallized in the form of cubic structure. Energy dispersive X-ray spectroscopy (EDX) investigations reveal that the products are extremely pure and nearly stoichiometric. The results obtained by scanning electron microscopy (SEM) demonstrate that the nanocrystalline ZnS prepared in presence of the RTIL are smaller than the prepared sample in water. Diffuse reflectance spectra (DRS) of the products prepared in presence of the RTIL demonstrate blue shift relative to the bulk ZnS. Photocatalytic activity of the nanocrystallines towards photodegradation of methylene blue (MB) was determined. Observed first-order rate constant of the reaction on the nanocrystallines prepared in presence of the RTIL is about four times greater than the prepared sample in water.