Growth of ZnO nanostructures with different morphologies by using hydrothermal technique

ZnO nanostructures, including nanotowers, nanovolcanoes, nanorods, nanotubes, and nanoflowers, have been grown by using the hydrothermal technique. Most of the ZnO nanostructures show the perfect hexagonal cross section and well-faceted top and side surfaces. The basic chemistry and growth mechanism are discussed. By increasing the reaction time, the volcano-like and tube-like ZnO structures were formed due to the Ostwald ripening process and the selective adsorption of the complexes. By using the seed layer, the dense-arrayed, regular oriented ZnO nanorods were obtained due to the decreased nucleation barrier and the abundant interfaces as well as the increasing surface roughness.