Controlling nanosized ZnO growth kinetics using various Zn:OH concentration ratios

Zinc oxide particle growth from homogeneous solution was monitored using in situ UV-vis spectroscopy. Final particle size and overall growth rates increased with increasing zinc to hydroxide concentration ratio and with the use of acetate as compared to tribromoacetic acid as surfactant additive. Particle growth was fit using three models: (1) the commonly used linear coarsening model, (2) the classic coarsening model, and (3) the simultaneous coarsening and oriented aggregation model. Both the classic coarsening and the simultaneous coarsening and oriented aggregation model produce reasonable fits of the data. In the case of the classic coarsening model, a value of n = 3, which is consistent with diffusion-limited coarsening, produced the best fit. However, the simultaneous coarsening and oriented aggregation model was slightly better at describing the early stages of growth, which is indicative of a substantial contribution to growth by oriented aggregation. High-resolution transmission electron micrographs confirm oriented aggregation at the early stages of growth, and the degree of oriented aggregation was substantially higher for experiments using tribromoacetic acid as compared to acetate.