Sol–gel/hydrothermal synthesis of well-aligned ZnO nanorods

The nucleation and growth of ZnO nanorods by hydrothermal method onto seed layer deposited onto an ITO/PET substrate. Concentrations of 10 and 15 mM were used for the synthesis of the seed layer solution, as well as 10 and 15 mM for the hydrothermal treatment, it is noted that the entire process was carried out at low temperature (<100 °C). The synthesis of ZnO nanorods was carried out in two stages: (i) A nucleation process, using the sol–gel method to obtain a seed layer; and (ii) a growth process, using the hydrothermal process to promote the perpendicular growth of ZnO nanostructures. The X-ray diffraction (XRD) ZnO results revealed a preferential orientation along the (002) axis, with a wurtzite hexagonal structure. The crystallite size (27 nm) and Gibbs free energy of the films were calculated, which exhibited a minimum diameter for the nucleation of ZnO nanorods (22 and 30 nm of the core diameter). The thickness layer is between 200 and 500 nm. These results indicate that ZnO nanorods with an average diameter between 50 and 195 nm are obtained, oriented perpendicularly to the ITO/PET substrate, synthesized by a low temperature process. Their potential applications are in power generators and sensors.