A solid control strategy for preparation of silver nanoparticles in aqueous medium

Abstract

Uniformly distributed, spherically shaped, mild concentrated silver nanoparticles with single-digit to hundreds nm size have been prepared by reducing silver nitrate with popular reducers like sodium borohydride or hydrazine in the presence of ordinary stabilizers such as SDS, PVP, Polysorbates and ultrasonication. Uv-visble spectroscopic analysis, particle size analysis, and particle-imaging through transmission electron microscopy (TEM) were used for nanoparticle characterization. Higher temperature accelerated the reduction rates, which follows the typical autocatalytic kinetics. Particularly, ultrasonication helped to facilitate the crucial stage of reduction phase to result in excellent quality of nanosolution, such as narrow distribution of particles and size uniformity. We found that initial location or arrangement of silver ions in clouds of stabilizers and 'effectve mixing' in the stage of reduction were vital for successful preparation of silver nanosolution. Also, reagent/stabilizer ratio, reducer input, solution environment such as pH, temperature, and stabilizer properties were optimized and discussed in detail. Proper selection of stabilizer and molar ratio to reagent and effective 'mixing' for preventing grain growth needs to be investigated more in the future work.