Synthesis of functional nanoparticles using supercritical fluids

In this review, we discuss the synthesis of functional nanoparticles using supercritical fluids, focusing on their unique characters. Enhanced transport properties, larger solubility, and easy operation in changing the phase behavior realize the instantaneous formation of solid products, leading to the synthesis of fine nanoparticles with narrow size distribution. Several methods are shown to prepare organic and inorganic nanoparticles using supercritical carbon dioxide or water. We then introduce our recent activities on the supercritical hydrothermal synthesis of metal oxide nanoparticles whose surface is modified with organic molecules. The organic molecules change the surface chemical character of the metal oxide nanoparticles, facilitating their handling and hybridization. We hope that this review provides a guide to the synthesis of various nanoparticles that are used as a key component for functional materials and future nanodevices.