Facile synthesis of inorganic nanoparticles by a precipitation method in molten ε-caprolactam solvent

Abstract

This work reports on a general route to synthesize inorganic nanoparticles. Using molten ε-caprolactam (CL, melting point = 69.2 °C) as a nonaqueous solvent and a stabilizer, various types of inorganic nanoparticles such as metal oxide, metal hydroxide and sulfide are readily synthesized via precipitation reactions of inexpensive precursors at about 100 °C for 2 h. These nanoparticles are relatively uniform in size and have relatively high crystallinity. Some of them such as ZnO and Fe₃O₄ have excellent optical and magnetic properties. Appropriate polarity, dielectric constant and coordinating effect are three key aspects for the formation of high-quality nanoparticles. The approach developed in this work would pave a new way for facile, low toxicity, solvent-recyclable and large-scale synthesis of inorganic nanoparticles with well-controlled dimensions and properties.