Influence of the reactant concentrations on the synthesis of ZnO nanoparticles.

We report on the synthesis of ZnO nanoparticles from Zn(CH3CO2)2 and NaOH in 2-propanol. Nucleation and growth are fast, and hence at longer times the particle size is controlled by coarsening. The coarsening kinetics are independent of the Zn(CH3CO2)2 concentration between 0.5 and 1.25 mM at a fixed [Zn(CH3CO2)2]:[NaOH] ratio of 0.625. The width of the size distribution was found to increase only slightly with aging time. In addition, at a fixed Zn(CH3CO2)2 concentration of 1 mM, the kinetics are independent of the [Zn(CH3CO2)2]:[NaOH] ratio between 0.476 and 0.625. The presence of water in the reaction mixture was found to only slightly affect the coarsening kinetics for water contents larger than about 20 mM. For lower water concentrations, the nucleation and growth of ZnO were very slow. It can be concluded that the synthesis method described provides a reliable source of ZnO nanoparticles due to its insensitivity to the reactant concentrations and the presence of water.