Highly monodisperse and sub-nano silver particles synthesis via microemulsion technique

Highly monodisperse silver nanoparticles were synthesized by chemical reduction of silver nitrate dissolved in water core of one microemulsion and sodium borohydride (reducing agent) dissolved in water core of another microemulsion. The surfactant used in the study was di-octyl sodium sulfosuccinate or aerosol OT (AOT), which is an effective surfactant for synthesizing silver nanoparticles in microemulsion. In the present work, influence of water-to-surfactant mole ratio (ω), molar ratio of reducing agent-to-silver nitrate (R′) and stirring effect on silver nanoparticles size and size distribution were studied. In the present work cyclohexane was chosen as continuous oil phase. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) were used for elucidating the structure, size and size distribution of the synthesized silver nanoparticles. TEM micrographs show that the synthesized nanoparticles were having average diameter of 5.5 nm, which increased ω. Isooctane was also used as a continuous oil phase to study the influence of water-to-surfactant ratio. The results showed a highly monodisperse and sub-nano size silver particles formation. The surface area of the synthesized particles was calculated to be 1.46 × 1010 mm2/g. An increase in R′ from 0.66 to 1 resulted in slightly smaller nanoparticles production, but on further increase of R′ led to bigger particles formation.