Formation Mechanism of ZnO Nanorod Superstructures in Different Solvents

Hierarchical superstructures consisting of nanoscale building blocks show great potential in achieving configurable properties. In this work, two patterns of ZnO nanorod superstructures are obtained directly by thermal decomposition of zinc acetylacetonate in different solvents. Namely, fan-shaped structures are obtained in methanol, whereas side-by-side assembly is achieved in n-pentanol. Time-dependent observations indicate the formation of quasi-spherical particles at the beginning of the reaction, which later transform into different superstructures depending on the types of solvents. The selective formation of superstructures is rationalized based on the calculation of interaction potentials between two nanorods with either crossed or side-by-side spatial organizations. The results reveal the significant role of solvents in affecting electrostatic repulsion, which may compete with attractive van der Waals forces leading to the favored superstructures.