Synthesis And Catalytic Activity Of Au NPs And PS/Au Composites

Gold nanoparticles(Au NPs) have been applied in many fields for its unique physical, chemical properties and good biocompatibility. The novel preparation methods of Au NPs always are a key factor for these applications. In this paper, two kinds of novel methods were applied in preparation of Au NPs, the CPS/Au and PS/Au composites were prepared via a method of anchoring Au NPs onto PS microspheres.The structure of resulted Au NPs, CPS/Au composites and PS/Au composites were characterized. The catalytic activity of resulted Au NPs, CPS/Au and PS/Au composites were investigated.1. We first reported an eco-friendly method for the synthesis of stable and crystalline Au NPs by using extract solution of the skin and the leaf of mungbean as reducing agent. The structure and morphology of Au NPs were characterized by UV-visible absorption spectra(UV-visible), Transmission electron microscopy(TEM), and Fourier-transform infrared spectra(FTIR), respectively. The effects of process temperatures, reaction time, and the concentrations of HAu Cl4 on the resulted Au NPs were discussed. Catalytic activity of Au NPs was investigated. The reduction mechanism of the HAu Cl4 using the extract solution of mungbean skin as reducing agent were investigated. The results have showed: Au NPs with varies shape have been obtained by using extract solution of mungbean skin as reducing agent. The Au NPs with quasi-sphere and an average diameter of 20 nm were prepared by using the leaf extract of mungbean seedlings as reducing agent. The prepared Au NPs exhibited catalytic activity for the reducing reaction of p-nitrophenol using sodium borohydride as reducing agent.2.We first developed a simple and reproducible method to prepare the Au NPs by using aldehydes(formaldehyde, N-propylaldehyde, N-pentanal, heptaldehyde or N-nonylaldehyde) as reducing agent. The structure and morphology of Au NPs were characterized by UV-visible, TEM, respectively. Catalytic activity of Au NPs was investigated. The results have showed: the oil-soluble aldehydes can also reduce aqueous HAu Cl4 in the interface of oil-water Au NPs. The existence of sodium hydroxide in this reaction system is crucial for the formation of Au NPs. Stable and well-dispersed Au NPs with the size of 10 nm are obtained by using heptaldehyde as reducing agent. The Au NPs with lager size and different morphologies, such as triangles, can be obtained by using formaldehyde and N-nonylaldehyde as reducing agent. The prepared Au NPs exhibited catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol with an amount of Na BH4.3. Carboxylated polystyrene microsphere(CPS) was prepared by suspension polymerization. CPS/Au composites were prepared by direct mixing of CPS microspheres and Au NPs nanoparticles. The CPS/Au composites were characterized by scanning electron microscope(SEM), thermogravimetric analysis(TG) and UV-vis, respectively. The catalytic activity of resulted CPS/Au composites was investigated. The results have showed: the size distribution of resulted CPS/Au composite is uniform with the size of 8 μm.The CPS microspheres were coated with dispersed Au NPs, and the weight percent of Au NPs in CPS/Au composite is about 25%. The prepared CPS/Au composite exhibited catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol with an amount of Na BH4.4. PS microspheres were prepared by a dispersion polymerization, the Au NPs were “anchored onto” the surface of PS microspheres by a thermodynamic driving force. The PS/Au composite were characterized by SEM, Differential scanning calorimetry(DSC), TG and UV-vis, respectively. The catalytic activity of resulted PS/Au composites was investigated. The results have showed: the size distribution of resulted PS/Au composite is more uniform with the size of 1.5-3.0 μm. The dispersed Au NPs were anchored onto the surface of PS microspheres, and the weight percent of Au NPs in PS/Au composite is about 15%. The prepared PS/Au composite exhibited catalytic activity for the reduction of 4-nitrophenol to 4-aminophenol with an amount of Na BH4.