Development of a wet chemical method for the synthesis of arrayed ZnO nanorods

A two-step wet chemical process with economic and practical advantages was developed to prepare arrayed ZnO nanorods on glass substrates using zinc acetate dihydrate (Zn(CH3COO)2·2H2O, ZnAc2) and monoethanolamine (NH2CH2CH2OH, MEA) as raw materials. The proposed method includes the pre-deposition of a thin ZnO seed layer using the sol-gel technique and the subsequent hydrothermal growth of ZnO nanorods at 130 °C for 2 or 4 h. The synthesis process was monitored using X-ray diffraction (XRD), Fourier transformation infrared (FTIR) spectroscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The ZnO nanorods exhibited a diameter of 25-75 nm with an aspect ratio ranging from 10 to 50 after growing for 4 h. Each ZnO nanorod was confirmed to be a single crystal with a wurtzite structure and grow along the [0 0 0 2] direction during the hydrothermal process. Photoluminescence (PL) measurements confirmed that the ZnO nanorods exhibited a near-UV emission at ∼380nm together with a green emission that was centered at ∼500 nm. We note that the PL properties may be affected by the hydrothermal time.