Size tunable synthesis of silver nanoparticles in water–ethylene glycol mixtures

Silver nanoparticles having narrow size distribution were synthesized in ethylene glycol–water mixtures without using any stabilizer. The formation of the Ag nanoparticles was monitored using UV–vis absorption spectroscopy. Size of the nanoparticles can be well controlled by varying the solvent composition. The product was analysed by dynamic light scattering and transmission electron microscopy. To elucidate the mechanism the effect of variation in polarity and viscosity on diffusion and non-diffusion controlled reactions of silver ions with reducing radicals was monitored by kinetic spectrophotometric technique. It was observed that adsorption of ethylene glycol at the surface of dimmer silver cluster leads to the formation of a ligand-to-metal charge transfer (LMCT) band at around 390 nm. The surface plasmon absorption band of stable silver clusters obtained by bombardment with electron pulses of mixtures of water:ethylene glycol media showed an absorption maximum at around 410 nm.