Facile templateless fabrication of ZnO nanostructures: A consideration of several parameters

Abstract. ZnO nanostructures were formed via a hydrothermal reaction mechanism between simple anionic (ammonia or sodium hydroxide) and cationic (zinc acetate dehydrate) precursors without using any organic templates. Eects of the reaction conditions, including the initial solution pH, type and concentration of the anionic and cationic precursors, and the reaction time and temperature, on the nanostructure particle size and morphology were investigated. The nanostructures formed were analyzed by powder X-ray diraction, energy dispersive X-ray analysis, and scanning electron microscopy. According to the results, the morphology of the nanostructures is highly pH-dependent. Needlelike nanostructures were formed using ammonia at initial solution pH value around 9, but plate-like nanostructures were formed using NaOH at pH value around 13, regardless of the reaction time or temperature. The precursors concentration could not be considered as an independent parameter per se as it consequently changes the reaction medium pH, which aects the morphology in turn. In general, increasing the reaction time and temperature increased the mean particle size of the nanostructures with no signicant change in their morphology. It was found that the nanostructure morphology changes from nanoneedle to star-like at higher addition rates of ammonia.