Solvent effects on gold nanoparticle formation from photochemical reduction of Au(III) by UV irradiation

Colloidal gold nanoparticles (AuNPs) have attracted more and more attention in areas of materials science, biotechnology and organic chemistry due to their unique functions as molecular markers and their applications in diagnostic imaging and catalysis. The AuNP synthesis approaches have been well developed; however, the solvent effects have not been systematically studied yet. Here we analyzed and compared solvent effects on AuNP formation using UV irradiation of Au(III) without adding any other ligands. By monitoring the surface plasmon resonance absorption of Au(III)-containing solutions, results showed that both ketone and alcohol solvents can induce Au(III) to form gold nanospheres; on the other hand, solvents like ACN and THF can induce Au(III) to form nanostructures with longer dimensions. The possible mechanism was discussed, which could facilitate efficient photochemical synthesis of AuNPs and might apply to other metal NP synthesis.