Effect of ligand structure on the catalytic activity of Au nanocrystals

The surface coating-dependent catalytic activity of icosahedral Au nanoparticles (IAuNPs) for the reduction of 4-nitrophenol by NaBH4 in aqueous solution was investigated. Cetyltrimethylammonium bromide (CTAB)-stabilized IAuNPs with average size of 50 nm were prepared by three-step seeding protocol. The CTAB was then exchanged with several amine derivatives such as pyrrole, pyridine, 2,2′-bipyridine, and 4,4′-bipyridine. The catalytic reaction rates of nanoparticles are in the order of IAuNPs@4,4′-bpy > IAuNPs@2,2′-bpy > IAuNPs@pyridine > IAuNPs@pyrrole > IAuNPs@CTAB, revealing that the catalytic activity of the nanoparticles highly depends on the type and structure of the ligand molecules.