Photochemical synthesis of gold nanoparticles by the sunlight radiation using a seeding approach

A novel photochemical synthesis of colloidal gold particles has been studied based on a seed-mediated growth approach under the UV solar radiation on plateau. In the HAuCl4 solution containing certain amounts of protective agent and acetone, the colloidal gold particles with 5 nm (sigma=0.86) in average diameter were prepared by UV 300 nm irradiation and used as seeds, their further growth then was carried out in the identical constituent solutions under the UV solar radiation. The results showed that to control the molar ratio of seed to Au(III) ion and use repetitive seeds can obtain different sized and surface-confined gold nanoparticles, and it is completely possible to utilize the UV solar radiation on the plateau with the higher elevation for the size-controlled synthesis of monodisperse gold nanoparticles under suitable conditions. The mechanism of the nucleation, growth and stabilization of gold particles were discussed in detail.