Facile synthesis of three-dimensional ZnO hierarchical microspheres composed of well-ordered nanorods by hydrothermal method

Three-dimensional (3D) ZnO hierarchical microspheres composed of well-ordered nanorods were synthesized by a facile one-step hydrothermal method without any surfactants. The effects of reaction conditions including reaction temperature, reaction time on the microstructure of hierarchical microspheres were investigated. The results demonstrated that the reaction conditions played an important role in the morphology of 3D ZnO hierarchical microspheres. A three-stage reaction mechanism of 3D ZnO hierarchical microspheres was proposed. Firstly, Zn2+ reacts with OH− and NH4+ to produce nanoparticles. Then the nanoparticles are self-assembled into nucleis. Finally is the formation and growth of the hierarchical structure on the nuclear surface. When the as-synthesized ZnO were used as the anode of the dye sensitization solar cells (DSSCs), the 3D ZnO hierarchical microspheres composed of well-ordered nanorods exhibits the best photoelectric properties, which was attributed to the increased surface area and advantageous electronic transmission path.