Growth of flower-like ZnO on ZnO nanorod arrays created on zinc substrate through low-temperature hydrothermal synthesis

Flower-like ZnO with various morphologies on ZnO nanorod arrays have been hydrothermally fabricated using zinc substrates at low temperature (70 °C). The time-dependent experiments indicated that both dense ZnO nanorod arrays and flower-like ZnO were created when the reaction time is 30 min. A growth mechanism was proposed to account for the growth of the flower-like ZnO on ZnO nanorod arrays. In situ growth caused the generation of dense ZnO nanorod arrays that were almost perpendicular to the surface of a zinc substrate. Due to the different rate of nucleation and crystal growth the morphology of flower-like ZnO on the top of ZnO nanorod arrays varied with the concentration of OH−. The ionic radius of alkali metal hydroxide used to generate Zn(OH)42− ions greatly affected the morphology of ZnO. Owing to the small quantity of ZnO nuclei and Zn(OH)42− the flower-like ZnO on ZnO nanorod arrays became fewer when lowering the concentration of Zn2+ and OH− while keeping the ratio between them.