A controllable hydrothermal synthesis of uniform three-dimensional hierarchical microstructured ZnO films

ZnO films composed of uniform three-dimensional (3D) hierarchical microstructures on the conductive glass were synthesized by a one-step polyethylene glycol-assisted hydrothermal route with excellent reproducibility. The morphology of the ZnO hierarchical structured films was controlled by adjusting hydrothermal reaction conditions, i.e., time, temperature, reactant concentration, Zn source and surfactant. A specific growth mechanism for the ZnO hierarchical microstructured films is proposed, and the hydrothermal time is found to be a crucial role in the formation of the hierarchical structures either from the initial nucleation and growth of the primary rods or secondary/tertiary nucleation and growth on the the column facets of the primary rods. As-fabricated ZnO films show a strong photoluminescence emission peak at 435 nm, and a superhydrophobic adhesive surface with a water contact angle of 154.1° and a high contact angle hysteresis.