Preparation of size‐controlled silver nanoparticles by the hydrothermal method

Abstract

AbstractWe have examined the hydrothermal synthesis of silver nanoparticles using the flow‐type reactor system. The reactor was designed to allow for the quick mixing of two kinds of reaction solutions; solution 1 containing silver nitrate and solution 2 containing a reducing reagent along with polyvinylpyrrolidone as a stabilizer, under hydrothermal conditions. It was found that, among the reaction conditions examined, the temperature of about T =300 °C and pressure of P =20∼23 MPa were the optimal condition for the synthesis of fine and uniform Ag nanoparticles. The flow rate of solutions fed into the reactor also had a significant influence on the size distribution of obtained Ag nanoparticles. The flow rate higher than 10 cm3min–1 was favourable for the synthesis of uniform nanoparticles because of the effective mixing of solutions. To facilitate the mixing of solutions, an orifice having 0.5 or 1.0 mm pinhole at the center was installed inside the reactor. It was confirmed that the use of orifice is of great benefit for the synthesis of fine Ag nanoparticles with a narrow size‐distribution. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)