Supercritical hydrothermal synthesis of nanoparticles

Some important aspects of supercritical hydrothermal synthesis of nanoparticles are (i) nanoparticle formation, (ii) single crystal formation, (iii) the ability to control particle morphology to some extent with pressure and temperature, and (iv) the ability to create a homogeneous reducing or oxidizing atmosphere by introducing gases or additional components (02, 142). In this study, another important aspect of supercritical hydrothermal synthesis was discovered; that is, in-situ surface modification of nanoparticles with alcohols, aldehydes, or carboxylic acids during crystallization. This paper also describes the simulation of the supercritical hydrothermal synthesis process, based on fluid dynamics, kinetics, solubility, nucleation, particle growth, and particle coagulation. Simulation results are compared with experimental results to elucidate the effect of mixing on the nucleation and growth of particles. Based on the simulation results, the mixing method and solution flow rate have been optimized to continuously produce ZnO whiskers with high crystallinity and good opto-electronic properties.