Synthesis and characterization of ZnO nanorods prepared using microwave-assisted hydrothermal method

ZnO is one of the most studied semiconductor materials for many applications; however, the synthesis of one-dimensional ZnO nanostructures by a simple and low-cost method in a short time is still a big challenge. The hydrothermal method is a simple way to produce nanostructures but the process is usually slow. However, the reaction can be accelerated using microwaves. This study aims to grow ZnO nanorods were on the glass substrates using ultrasonic spray pyrolysis and microwave-assisted hydrothermal methods. Our goal was to investigate the effect of the concentration of the growth solution containing equimolar amounts of hexamethyelenentetramine and zinc nitrate tetrahydrate (0.05, 0.1, and 0.15 M) on the morphology and structural and optical properties of the ZnO nanorods. Scanning electron microscopy, X-ray diffraction, and ultraviolet (UV)-visible spectroscopy studies demonstrated that an increase in the concentration of the growth solution results in an increase in the lattice parameters, unit-cell volume, crystallite size, density, and diameter of the nanorods. In addition, increasing the precursor concentrations improves the optical absorbance in the UV region and leads to a slight increase in the bandgap energy (from 3.20 to 3.22 eV).