2018 Volume 61 Pages 3-13
In supercritical water, ions are un-stabilized because of the lower dielectric constant, and metal oxides formed from metal salts. Thus, supercritical water is a good reaction atmosphere to synthesize nano metal oxides, when a metal salt solution is rapidly heated up to the supercritical state. To achieve the rapid heating, flow type reaction process in which metal salt solution is rapidly mixed with high-temperature water was employed. In most of the cases for nanoparticles applications (nano fluids/nano composite materials), nanoparticles have to be well-dispersed in solvents/polymers at high concentration, with keeping fluidity high. Thus, affinity control between the particles and matrix is the critical issue. In supercritical water, organic ligands can be miscible with water due to the low dielectric constant, so that in situ surface modification is possible during the synthesis of nano metal oxides. Based on this nano materials synthesis technology, a variety of applications of nanoparticles is expected including nano hybrid materials and nanocatalysts.
