Fabrication and Characterization of ZnO Nano-Clips by the Polyol-Mediated Process

ZnO nano-clips with better monodispersion were prepared successfully using zinc acetate hydrate (Zn(OAc)₂·nH₂O) as Zn source and ethylene glycol (EG) as solvent by a simple solution-based route-polyol process. The effect of solution concentration on the formation of ZnO nano-clips has been investigated deeply. We first prove that the 0.01 M Zn(OAc)₂·nH₂O can react with EG without added water or alkaline, producing ZnO nano-clips with polycrystalline wurtzite structure at 170 °C. As-synthesized ZnO nano-clips contain a lot of aggregated nanocrystals (~ 5 to 15 nm) with high specific surface area of 88 m²/g. The shapes of ZnO nano-clips basically keep constant with improved crystallinity after annealing at 400-600 °C. The lower solution concentration and slight amount of H₂O play a decisive role in ZnO nano-clip formation. When the solution concentration is ≤ 0.0125 M, the complexing and polymerization reactions between Zn(OAc)₂·nH₂O and EG predominate, mainly elaborating ZnO nano-clips. When the solution concentration is ≥ 0.015 M, the alcoholysis and polycondensation reactions of Zn(OAc)₂·nH₂O and EG become dominant, leading to ZnO particle formation with spherical and elliptical shapes. The possible growth mechanism based on a competition between complexing and alcoholysis of Zn(OAc)₂·nH₂O and EG has been proposed.