A facile synthesis of high optical quality silver nanoparticles by ascorbic acid reduction in reverse micelles at room temperature.

We report a convenient synthesis of silver nanoparticles (AgNPs) using ascorbic acid (AA) as a reducing agent in sodium dioctylsulfosuccinate (AOT) reverse micelles at w0 (=[water]/[AOT]) values of 2, 6 and 10. Simple injection of silver nitrate and AA solutions into AOT/n-heptane mixtures leads to formation of nanoparticles at room temperature in the absence of inert atmosphere or prolonged stirring. The optical quality of the surface plasmon resonance (SPR) band of the synthesized AgNPs was found to be superior (stronger peak and narrower bandwidth) than for AgNPs obtained by common reducing agents like sodium borohydride or hydrazine under similar conditions. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements revealed that the nanoparticles are spherical, and are slightly larger than the pure reverse micelles. Also, the size and the polydispersity increase with increase in the w0 value.