High-yield self-assembly of flower-like ZnO nanostructures

High-yield three-dimensional (3D) flower-like nanostructures self-assembled from 1D ZnO nanorods and nanotubes are experimentally demonstrated. The Zn and O terminated crystal planes of ZnO nanorods results in positively and negatively charged top (001) and bottom (00-1) surfaces, respectively. The nanorods self-assembled into 3D nanostructures via the electrostatic interaction between the crystal planes with opposite charges. Moreover, on the basis of the different stability of polar and nonpolar planes in wurtzite-type ZnO, the nanorods based 3D nanostructures transformed into nanotubes based ones spontaneously This provides a new approach to prepare multi-dimensional materials without the necessity to employ any external intervention.