Template-free preparation and characterization of nanocrystalline ZnO inaqueeus solution of [EMIM][EtSO_4] as a low-cost ionic liquid using ultrasonicirradiation and photocatalytic activity

摘要

A fast, template-free, and environmentally benign green route for the preparation of nanocrystallineZnO in aqueous solution of 1-ethyl-3-methylimidazolium ethyl sulfate, [EMIM][EtSO_4], room-temperature ionic liquid (RTIL), via ultrasonic irradiation is proposed. The X-ray diffraction (XRD)studies display that the products are excellently crystallized in the form of wurtzite hexagonal. Energy-dispersive X-ray spectroscopy (EDX) investigations reveal the products are extremely pure. Themorphology of as-prepared nanocrystalline ZnO was characterized by scanning electron microscopy(SEM). Diffuse reflectance spectra (DRS) of the products with absorption maxima at 3.59 nm show blueshift relative to the bulk ZnO with absorption at 384 nm that can be attributed to quantum confinementeffect of nanocrystalline ZnO. A possible formation mechanism of the nanocrystalline ZnO usingultrasonic irradiation in aqueous solution of the RTIL is presented. The results demonstrate thatphotocatalytic activity of the nanocrystalline ZnO prepared in the presence of the RTIL is higher than the prepared sample in water.