Synthesis of ZnO microstructures in glycerol/water solution

Zinc oxide (ZnO) microrods with high aspect ratio and microstructures with flowerlike morphologies have been synthesized successfully in a glycerol/water reaction system by a simple solvothermal method without adding any surfactants or templates at 180 °C. Experimental results indicated that the flowerlike ZnO microstructures were transformed into rodlike ones with increasing amounts of zinc acetate dihydrate (Zn(Ac)2·2H2O) and sodium hydroxide (NaOH) because of the rapid nucleation and growth, indicating that the concentration of reactants is the key to control the morphologies of ZnO samples. In contrast, double-columned and double-hemisphered ZnO microstructures were fabricated using similar solvothermal conditions without adding NaOH by adjusting the proportion of glycerol and water, for these crystallites were generated mainly by esterification between Zn(Ac)2·2H2O and glycerol. Time-dependent experiments have also been conducted to explore the evolution of ZnO morphologies. The growth mechanism of as-prepared ZnO structures synthesized in different conditions was discussed.