Here we established a simple electrochemical method of synthesizing ZnO nanomaterials with high quality and the ability to control the nanostructures' density For ZnO nanorod growth, a thin layer of Al doped ZnO (AZO) was deposited on glass substrates and ZnO nanorod arrays were grown on these substrates from aqueous solution containing Zn(NO3)(2) and NH4NO3. It was found that the density, morphology, and quality of the nanorod arrays can be controlled by changing the applied potentials or the concentration of NH4NO3 in the solution as growing and etching were carried out simultaneously. Moreover, the nanorod density decrease resulted in an improvement of the quality of the as-grown nanorods. Scanning electron microscope (SEM), transmission electron microscopy (TEM), photoluminescence and X-ray diffraction (XRD) have been used to characterize the samples. The density of ZnO nanorods can be controlled by varying the concentrations of the precursor solutions or applied potentials. Passivated low-density ZnO nanorod arrays with high quality were fabricated. (C) 2017 Elsevier B.V. All rights reserved.