Size Distribution of Hexagonal Prismatic-Shaped ZnO Nanorods Synthesized by Microwave-Assisted Irradiation of Precursors

A microwave irradiation-assisted single-step method is used for the synthesis of ZnO nanorods with a hexagonal prismatic shape, using a customized domestic microwave oven. The effects of different process parameters, including precursor reagents, synthesis time and precursor concentration, are studied. The morphological, structural and optical properties of the ZnO nanorods are investigated using scanning electron microscopy (SEM), powder x-ray diffraction (XRD) and UV–Vis spectroscopy. It is observed that the average diameter of the ZnO nanorods depends on the precursor used, and ZnO nanorods with the smallest diameter of around 300 nm are synthesized when zinc nitrate (ZNH) is used as a precursor. The average diameter of the nanorods, on the other hand, increases as the precursor concentration and synthesis time increase. The average diameter varies from 300 nm to 500 nm depending on the concentration of the precursor, and the length of the nanorods varies within a range of 1.8–3.5 μm. The average length of the nanorods increases as the precursor concentration increases, to an optimum value of 15 mM. It is also observed that an increase in the average length (1.5–4 μm) is associated with the slight increase in diameter up to an optimum synthesis time of 20 min. The best length-to-diameter ratio of the synthesized ZnO nanorods using basic precursor solution is obtained at an optimum concentration of 15 mM and synthesis time of 20 min, using the customized system. Graphical Abstract ZnO nanorods are synthesized with microwave irradiation from a customized domestic oven. A low-cost and facile synthesis route for the production of high-aspect-ratio ZnO nanorods is reported. The size of the ZnO nanorods is controllable with different process parameters. The optical properties can be easily tuned by the size of the synthesized ZnO nanorods.