A modified polyol process for growing Ag nanowires and nanoplates using 2-ethoxy ethanol

Abstract

A modified polyol process was proposed to prepare Ag nanowires in this study. The typical reductant, ethylene glycol, was replaced with 2-ethoxy ethanol in the presence of polyvinylpyrrolidone (PVP) to grow Ag nanowires and nanoplates. The growth of Ag nanowires was monitored by the UV–Visible spectrum, which depends on the geometry-dependent surface plasmon resonances of the Ag nanowires. The crystal phase of the Ag nanostructures was identified by X-ray diffraction. Transmission electron microscopy showed that the average dimensions of the Ag nanowires were lengths of approximately 2–10 μm and diameter of 80 nm. The PVP molecules played a key role in directing the growth of the Ag nanostructures along the (111) crystal plane, and the reduction rate of Ag+ at 25 °C when 2-ethoxy ethanol was used was faster than when ethylene glycol was used, which improved the growth of the Ag nanowires. When the AgNO3-to-PVP ratio was adjusted to 2, multiple twinned particles could be observed at an initial stage of the reaction, and a higher yield of the Ag nanowires was synthesized. When the PVP drop rate was slowed, more Ag nanowires were grown. Interestingly, when the AgNO3 and PVP molecules were initially premixed, Ag nanoplates were generated, rather than nanowires, at a higher temperature in this reduction system.