Synthesis and characterization of silver nanoparticles

Abstract

Silver nanoparticles may be prepared in aqueous solution by reducing silver nitrate with borohydride in the presence of sodium citrate and 4-4-(phenylphosphinidene) bis-(benzene sulfonic acid) (BSPP). Variation of the reaction conditions produces nanoparticles of different sizes, shapes, and chemical properties. For instance, the resistance to oxidation in the presence of cyanide can be increased by synthesizing nanoparticles using a high concentration of citrate. The differing chemical properties also show different results when using silver nanoparticles as a catalyst for the reduction of dichlorofluorescein. An induction time for the reduction reaction to begin was longer when nanoparticles were used that had been synthesized with a high concentration of BSPP. Finally, the surface effects of sulfur containing molecules on silver nanoparticles differ depending upon nanoparticle preparation. For example, silver nanoparticle solutions that were prepared with a high concentration of citrate showed a smaller shift in the Amax than those with a low concentration of citrate with the addition of L-cysteine.