In situ reduction and stabilization of Ag NPs onto magnetic composites for rapid hydrogenation catalysis

A novel core–shell-structured Ag-based magnetic functional polymer nanocatalyst, i.e., Fe₃O₄@SN/GLA@chitosan-Ag (SN represents animo-functionalized SiO₂, GLA signifies glutaraldehyde), was fabricated via a simple and environmentally friendly method. The magnetic separation property of Fe₃O₄, the protection effects of SiO₂, the reduction and stabilization activities of chitosan, and the catalytic property of Ag nanoparticles (NPs) in the multifunctional catalyst system were efficiently combined using glutaraldehyde as bridging agent. The Ag NPs with average diameter about 2–11 nm were generated in situ and stabilized by chitosan, which acted as reducing agent and stabilizer in the absence of other potentially toxic reagents. Furthermore, the reduction, chelation ability of chitosan, and the size of Ag NPs were found to be tunable, thereby enabling the preparation of other noble metal catalysts with tailored properties. Most importantly, the as-prepared catalyst exhibited superior catalytic performance (the reduction reaction was finished within 3 min) and reusability (reusable for at least six times) in the reduction of 4-nitrophenol.