In situ replacement of Cu-DEN: An approach for preparing a more noble metal nanocatalyst for catalytic use

The advantage of dendritic monodisperse macromolecules' dual templating ability was useful in the formation of silica-supported copper nanoparticles Cun@SiO2NPs. This was acquired by the initial synthesis of a silica framework (G4-PAMAM-NH2-SiO2) as a mesoporous support using amine-terminated generation 4 PAMAM dendrimers (G4-PAMAM-NH2). The encapsulated Cun@SiO2 NPs, calcined at 500 C, were made to undergo a displacement reaction with Au3+ generated from the equivalent molar addition of HAuCl4. This resulted in the formation of Aun@SiO2NPs upon in situ replacement at a regulated pH. The synthesized nanoparticles were characterized and examined. The catalysts were shown to be catalytically active in the hydrogenation of 4-nitrophenol, and oxidation of rhodamine B as model reactions, before oxidation of styrene using TBHP. Also, the stability of the catalyst was evaluated, and the catalytic activity was retained after three consecutive cycles.