Kinetics Study of ZnO Nanorod Growth in Solution

ZnO nanorods were synthesized via a solution synthesis method with temperatures ranging from 55 to 85 degrees C. The nanorods have a hexagonal cross-section length of 200-300 nm. Powder X-ray diffraction analysis showed the nanorods are single crystal materials. Using inductively coupled plasma technique, the Zn2+ concentration in solution was analyzed and the lengths of the nanorods were obtained from a SEM micrograph with ImageJ software. The concentration of Zn2+ could be described with a first-order reaction mechanism. Nanorod length analysis showed that lower temperature was beneficial to nanorod growth and high temperature resulted in a competition between nucleation and nanorod growth. With some reasonable assumptions, the correlation between the concentration of zinc ions and the length of nanorods was developed. The simple kinetics model developed in this paper agrees with the experimental results very well for low-temperature reaction, at which the nucleation could be ignored. However, at high temperature, due to the competition of nucleation with the particle growth, the experimental results deviate from the model prediction.