Environmentally benign magnetic chitosan/Fe3O4 composites as reductant and stabilizer for anchoring Au NPs and their catalytic reduction of 4-nitrophenol

Abstract

We report the facile synthesis of environmentally benign Au NPs/chitosan composites and magnetic Au NPs/chitosan/Fe₃O₄ composites without employing any toxic reductants or capping agents. Renewable natural chitosan not only functioned as supporting matrix, but also served as a reductant and stabilizer for the formation and dispersions of Au NPs. Fe₃O₄ nanospheres were easily embedded into the chitosan matrix due to the strong complexation ability of chitosan with Fe₃O₄, which originated from the sharing of the lone electron pairs from the nitrogen atom in amine with Fe^II or Fe^III on the surface of Fe₃O₄. The as-prepared magnetic composites exhibited much higher activities, as well as more convenient magnetic recyclability than other supported Au NPs towards the reduction of 4-nitrophenol. From the practical point of view, apart from good performance of the reduction of nitro compounds, the biocompatibility and biodegradability of present Au NPs/chitosan/Fe₃O₄ composites promote the potential applications in the biochemical catalysis or therapy.