Question

What is the mechanism of silver nanoparticle(citrate as the capping agent) aggregation induced by sodium ions?

Answer 1

Nanomaterial's properties and applications are dependent on their shape, size, and morphology of these structures. Silver Nanoparticles have considerably versatile properties, such as

1)a variable surface area to volume ratio, which is very useful for many biomedical and technological applications.

2)small nanoparticle aggregates can have their properties reduced due to the increased size and alterations in their shape/morphology.

Silver nanoparticles aggregation from chemical reduction of silver nitrate in the presence of sodium borohydride and sodium citrate. By changing amount of reducing agent along the reaction, unaggregated and partially aggregated samples were obtained and characterized by UV–vis, zeta potential, and SAXS techniques.

pH measured in every step of the reaction to correlate these results with those obtained from structural techniques. Addition of the reducing agent first causes the reduction of Ag⁺ to silver nanoparticles.

For higher concentrations of sodium borohydrate, the average Silver nanoparticle's size is increased and NPs aggregation is observed.

It was found that zeta potential and pH values have a strong influence on AgNPs formation, since reducing agent addition can induce partial removal of citrate weakly associated on the AgNPs surface and increase ionic strength of solution, promoting partial aggregation of the particles.