What are the roles of PVP and NaOH in the polyol synthesis of silver nanoparticles in glycerol?

PVP acted as a stabilizer to prevent particle growth and aggregation by a steric effect. In the absence of PVP, black precipitates formed instead of a yellow solution with a broaden absorption band. Increasing the PVP/Ag mole ratio to 10/1 increased absorption intensity, resulting in sharper bands and a shift to a shorter wavelength, indicating smaller and narrower distributed AgNPs. The two-electron oxidation steps of glycerol to form AgNPs were carried out in an alkaline medium (NaOH) to lower the reaction temperature. Without NaOH, the reaction did not occur at a low temperature (60 °C). The absorption peak intensity increased with NaOH concentration, peaking at 1.00 mM NaOH.

In the polyol synthesis of silver nanoparticles (AgNPs) in glycerol, polyvinyl pyrrolidone (PVP) acts as a stabilizer to prevent particle growth and aggregation, leading to smaller, more uniformly distributed nanoparticles. Sodium hydroxide (NaOH) creates an alkaline medium that lowers the reaction temperature required for the reduction of Ag(I) ions by glycerol.