Document Abstract
ZnO nanoparticles (NPs) were prepared by chemical precipitation method from zinc acetate
dihydrate and NaOH using isopropanol as the reaction medium. The influence of an
imidazolium-based hydrophilic ionic liquid (IL), 1-ethyl-3-methylimidazolium methylsulfate,
[EMIM][MeSO4] at different concenrations on the size and morpholgy of ZnO NPs was
investigated. The NPs were characterized by Fourier transform-infrared, energy dispersive Xray
and UV-visible spectroscopy, along with x-ray diffraction, particle size analysis, field
emission scanning electron microscopy and high resolution transmission electron
microscopy. Pure nanocrystalline ZnO with hexagonal wurtzite phase was formed in the
system. The particle size of the NPs varied in the range of 2-55 nm depending on the
concentration of the IL used during preparation. With increasing concentration of
[EMIM][MeSO4] the shape of the NPs also changed interestingly from spheres to flakes
through nanorods. The use of the IL has been proved effective as a self directing agent and
templating material for the successful preparation of ZnO nanostructures. Finally, the
mechanism for preparation of ZnO NPs with controllable size and morphlogy has been
established and the variation of size, shape and morphology has been explained in terms of
hydrogen bonding -co- π-π* stacking interaction between IL and the NPs.