Preparation and Characterization of ZnO Nanocrystallines in the Presence of an Ionic Liquid Using Microwave Irradiation and Photocatalytic Activity

M. Esmaili and A. Habibi-Yangjeh*

Department of Chemistry, Faculty of Science, University of Mohaghegh Ardabili, P.O. Box 179, Ardabil, Iran

Fast, simple and template-free method is proposed for preparation of ZnO nanocrystallines in the presence of 1-ethyl-3-methylimidazolium ethyl sulfate, [EMIM][EtSO₄], a room-temperature ionic liquid (RTIL) under microwave irradiation. The powder X-ray diffraction (XRD) studies display that products are excellently crystallized in the form of wurtzite hexagonal structure. Energy dispersive X-ray spectroscopy (EDX) investigations reveal that the products are extremely pure. The results obtained by scanning electron microscopy (SEM) demonstrate that mean size of ZnO nanocrystallines decreases with microwave irradiation time and the RTIL content of media. Diffuse reflectance spectra (DRS) of the ZnO nanocrystallines shows blue shift relative to the bulk ZnO, which can be attributed to quantum confinement effect of ZnO nanocrystallines. A possible formation mechanism of the ZnO nanocrystallines in aqueous solution of the RTIL is presented. Photocatalytic activity of the ZnO nanocrystallines towards photodegradation of methylene blue (MB) was carried out. The results demonstrate that photocatalytic activity of the ZnO nanocrystallines increases with microwave irradiation time and the RTIL content of media.

Keywords: Zinc oxide, Room-temperature ionic liquid, Nanocrystalline, Microwave irradiation, Photocatalysis