Investigating the Seed-Growth Method for the Synthesis of Silver Sols with Several Colors

The seed-growth method for the preparation of silver sols with several colors, other than its characteristic yellow color, was investigated during a nanochemistry student research project. The seed solution was obtained by synthesizing silver colloids with sodium borohydride as a reducing agent and was subsequently added to polyvinylpyrrolidone solutions containing silver nitrate. By controlling the concentrations of the aqueous solutions of both trisodium citrate and ascorbic acid in the growth solutions, we obtained orange, red, magenta, blue and green colors for the several silver sols. The optical properties from the aqueous silver sols were characterized by UV-Vis spectroscopy. These highly reproducible experiments are suitable for advanced nanochemistry courses. They also provide students with a thorough introduction on complementary colors.status: publishe