Synthesis And Properties Of Functional Gold Based Nano-composites

Gold is an important material with special optical, electrical properties and catalytic activity. In recent years, the research about it is obtaining more and more intensive study. But the price of gold is expensive, which limits its application in many fields. Development of nanomaterials, especially the gold nano-composites, provides a new way to utilize gold effectively. The composite materials not only maintain the special properties of gold, but also have many other advantages. Conductive polymer, organic hybrid silica nanospheres and functionalized graphene are the three outstanding categories of materials. It is significant to design simple and efficient method to prepare gold nano-composites and to increase the interaction between the gold and other nanomaterials.The Au, Pt and polypyrrole nanocomplex (Au-Pt@PPy) with a novel three-dimensional structure was synthesized by a facile one-pot reaction. Raman spectra, transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV-vis spectroscopy (UV-vis), and cyclic voltammograms (CV) were employed to characterize the complex. TEM and SEM results indicated that the products had novel three-dimensional (3D) multi-branch structures, which were controllable by simply adjusting the ratios of HAuCl4to H2PtCl6. Raman characterization proved that the products had significant surface-enhanced Raman Effect. CV results showed that the Au-Pt@PPy with coral-like structure had high catalytic efficiency for methanol oxidation. For improving stability and efficiency of gold nanomaterials, a straightforward one-step method was developed to synthesize Au-SiO2composite nanospheres. As the first step, monodisperse hybrid silica nanospheres which had anilino-methyl on the surfaces were prepared. The as-prepared hybrid silica nanospheres were then used to obtain Au nanocrystal through the redox reaction of HAuCl4and anilino-methyl. TEM, SEM, dynamic light scattering (DLS), and energy dispersive spectrometer (EDS) were employed to characterize the complex. By adjusting the surface morphologies and the particle sizes, the functional nanospheres displayed different surface enhanced Raman scattering effects of Rhodamine6G. The composite nanospheres showed surprisingly high catalytic activity and good reusability in catalytic reduction of4-nitrophenol.In order to improve the catalytic efficiency and the utilization of Au, we designed and synthesized the composite nanomaterial by Au with two-dimensional gold nanostructure dispersing on functional reduced graphene oxide (FRGO). TEM, AFM and EDS were employed to characterize the complex. The as-prepared Au nanoplates had regular triangular shape. The sizes and morphologies of the nanoplates were controllable by simply adjusting the ratios of HAuCl4to FRGO. The products with ultralow trace amounts of Au showed high catalytic activity in liquid-phase reduction of4-nitro phenol (4-NP).