title: Size-controlled deposition of Ag nanoparticles on alumina with the assistance of a photo-induced chromic reaction, and study of their catalytic properties.
abstract: This paper describes a promising method to synthesize supported metal catalysts based on a photochromic reaction. Highly dispersed Ag nanoparticles (NPs) with a mean diameter of ca. 10 nm stabilized by 3-mercaptopropionic acid (3-MPA) were prepared as a colloidal precursor solution. The zeta electric potential was found to be negatively charged in the region of pH higher than 5 due to the presence of dissociated carboxylate ions (-COO(-)), which led to electric repulsion between Ag NPs and kept the solution in a highly dispersed colloidal state. In the presence of photochromic molecules, trans-2-hydroxychalcone, the photo-irradiation gradually decreased the electric charge on the nanoparticles owing to the formation of flavylium cations, which induced the assembly of Ag NPs. Such photo-induced assembly-dispersion control of Ag NPs enables size selective deposition on a catalyst support, which is controlled by varying the photo-irradiation time.
authors.affiliation: Division of Materials and Manufacturing Science, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871.
authors.forename: Kohsuke
authors.initials: K
authors.lastname: Mori
authors.forename: Akihito
authors.initials: A
authors.lastname: Kumami
authors.forename: Hiromi
authors.initials: H
authors.lastname: Yamashita