Stabilization of Au-Ag Nanoalloys with Polyvinylpyrrolidone (PVP) as Capping Agent

Van der Waals attraction between nanoparticles will create aggregation, therefore, adding a capping agent is needed to stabilize the nanoparticles. We have synthesized Au50Ag50 nanoalloys from a mixture of silver and gold metal ions using a femtosecond laser irradiated for 5, 10, and 15 minutes. The process occurred in a water-only medium and in a water medium added with 0.01 wt% polyvinylpyrrolidone (PVP). Only Au50Ag50 with 5 minutes irradiation times that was characterized by TEM. From TEM result, PVP was proven to generate stabilization of the nanoparticles. It was confirmed that the nanoparticles in Au-Ag nanoalloys with PVP are more disperse than the Au-Ag nanoalloys without PVP. From the result, the particle size of Au-Ag nanoalloys without PVP is 10.72 nm, and 7.94 nm with PVP. This indicates that not only reducing the van der Waals attractive forces and stabilizing the nanoparticles, PVP can also reduce the particle size.