Rapid and high-yield synthesis of silver nanowires using air-assisted polyol method with chloride ions

摘要

Effects of gas bubbling were studied for synthesis of silver nanostructures from a mixture of AgNO3/NaCl/poly(vinylpyrrolidone) (PVP) in ethylene glycol (EG). Monodispersed silver nanowires were synthesized under oil-bath heating in high yield (>90% without isolation) using bubbling of air through a reagent Solution from ca. 20 C to the boiling point of EG (198 degrees C) for 20 min. On the other hand, mixtures of Cubes, bipyramids, and wires were prepared under bubbling of N-2. The Ag nanostructures growth mechanism Was studied by observing ultraviolet-visible (UV-vis) spectra and transmission electron microscope (TEM) images at various temperatures. Results show that the formation process of Ag nanostructures under gas bubbling is separable into two stages: a low temperature range of 20-180 degrees C at 0-17 min. where mixtures of variously shaped Ag seeds are produced independent of the bubbling gas; and a high temperature range of 180-198 degrees C at 17-20 min, where rapid growth of nanowires and oxidative etching of cubes and bipyramids by Cl-/O-2 occur simultaneously in bubbling of air, thereby producing long nanowires in high yield. Because the etching process is absent during processing by bubbling of N-2, mixtures of shorter nanowires, cubes, and bipyramids are produced.