Tuning aspect ratio of hierarchical ZnO nanotetrapod

Fine-tuning the aspect ratio is crucial for practical application and optimizing various properties of nanostructure. In this work, a mixed metal (Zn) and oxide (ZnO + C) powder was adopted as precursor to obtain initial high reagent vapour pressure and subsequent low reagent vapour pressure, and one kind of hierarchical ZnO nanotetrapod with legs composed of thick primary nanorod and thin secondary nanowire was successfully synthesized. Two growth stages controlled by the reagent supersaturation ratio were proposed to unveil the underlying growth mechanism of this hierarchical structure. Further, a series of comparative experiments were undertaken to validate the growth mode and explore the growth strategy tailoring the aspect ratio. Our results suggest one accessible approach to manipulate the aspect ratio, and the growth mode has some promises for preparing hierarchical nano-blocks with specific geometry demanding.