Synthesis of Ag Nanostructures with Controlled Shapes by a Polyvinylpyrrolidone-Assisted Hydrothermal Method

Abstract

Ag nanostructures with well-defined shapes and optical resonances have been masssynthesized by a hydrothermal method.Polyvinylpyrrolidone(PVP) polymers with average molecular weights(MW) of 8000,40000,160000,and 360000 denoted as K17,K30,K60,and K90,respectively,were chosen as surfactants(K is usually used to represent the characteristic value of relative viscosity of the PVP solution).It was found that the larger MW of PVP,the higher relative viscosity of the PVP solution.All of the reactants were transferred into a 60 mL stainless steel autoclave and heated at a certain temperature for hours.Five-fold twinned Ag nanodecahedrons with nearly uniform size were synthesized in the aqueous solution of K17.Ag nanowires were obtained with the presence of K30,K60,and K90 in ethylene glycol(EG) solution,and the aspect ratios of the Ag nanowires increased with increasing the MW of PVP.The morphology and microstructures of the obtained products were characterized by transmission electron microscopy(TEM) and field emission-scanning electron microscopy(FE-SEM).The surface plasmon resonance(SPR) spectra of the Ag nanostructures were measured using an UV-Vis spectrophotometer.The results showed that the surface plasma resonance of the Ag nanostructures was dependent on their shape and size.