In-situ synthesis of noble metal nanoparticles in alginate solution and their application in catalysis

Integration of eco-friendly method into metallic nanotechnology is one of the key issues in the field of nanoscience research. In this work, we reported a facile method to synthesize noble metal (Pt, Au, and Pd) nanoparticles in sodium alginate (SA) aqueous solution at 100 degrees C. The SA provides circumstance for reducing the metal precursors to their corresponding elemental states, and also acts as stabilizing agent for these metal nanoparticles. X-ray photoelectron spectroscopy of the as-produced metal-SA composites showed that the metallic form was the dominant species in the SA matrix under the experimental conditions. Transmission electron microscopy demonstrated that the metallic nanoparticles prepared in this way appeared to be homogeneous and their sizes were well within quantum size domain (<10 nm). The size and size distribution of the metal nanoparticles can be adjusted by altering the concentration of the metal precursors. The Pt-SA suspension could be cross-linked with divalent ions to form beads with porous structure at room temperature. The reaction behavior of cyclohexene hydrogenation suggested that the resultant Pt-alginate composites exhibited high catalytic activity.