Preparation of uniform 2D ZnO nanostructures by the ionic liquid-assisted sonochemical method and their optical properties

Uniform 2D ZnO nanostructures were successfully synthesized by a sonochemical method, using 1,4-diazabicyclo[2.2.2]octane (DABCO) and imidazolium-based ionic liquids in water as the solvent after 30 min. The effects of ionic liquids as template on the morphology and size of nanostructures were investigated. The structural and optical properties of ZnO nanostructures were studied by using XRD, SEM and UV–visible. The characteristic results revealed that using ionic liquids in water not only prevents a drastic increase in the crystallite size of the zinc oxide species but also provides suitable conditions for the oriented growth of primary nanoparticles with nanosheet morphology. SEM revealed that using the longer alkyl chain at position-1 of DABCO or dicationic ionic liquids causes a uniform nanosheet and nanoleaf. A possible mechanism was proposed to explain the formation of ZnO nanostructures with nanosheet morphology. Also band gap variation with particle size was investigated.