Study On Preparation And Properties Of Ag/Au-Chrysotile Composites

Surface-enhanced Raman Scattering has seen an enormous improvement during the last decade, originating from potential applications of these systems in a wide variety of attractive fields, ranging from molecular detection and microelectronics to medical diagnostics and catalytic. In this paper, the silicon oxide nanowires were synthesized with the natural mineral chrysotile as the raw material to fabricate silicon nanowires by using the magnesiothermic reduction method. After modified the nanowires by silane coupling agent, it was used decorated Au and Ag nanoparticles to prepare the Ag/Au-SiO2 nanowires materials. The resultant samples were characterized by means of the thermal analysis, X-ray diffraction, scanning electron microscope(SEM) and transmission electron microscopy(TEM) to analyze the phase structure and morphology characteristics. UV-vis was used to research the catalytic performance of the composite materials towards the reduction reaction of 4-NP.(1)The silicon oxide nanowire was synthesized with the natural mineral chrysotile as the raw material, and used as the oxidant and templates to prepare silicon nanowire by magnesiothermic reduction method. The results show that the temperature plays a crucial role on the structure and morphology of silicon. With the increasing of reaction temperature, the crystallinities of samples decreased firstly and then increased, silicon inherited the microstructure of the original templates at 650℃. However, the nanowire structure collapsed when the temperature reaches to 700 ℃, and convert to nanoparticles.(2) The pre-processing and self-assembling method was employed to prepare Ag/Au-SiO2 nanowires, which used the Silicon oxide nanowires as the substrate,silver nitrate or gold acid as precursor,sodium borohydride as reducing agent, trisodium citrate as surfactant and deducting agent, the double reduction method and hydrothermal synthesis method was used to synthesis Ag/Au-SiO2 nanowires materials.The results show that the gold or silver nanoparticles grow on the surface of silica nanowires successfully without aggregation, the nanowire structure was not collapsed when the gold or silver nanoparticles decorated silica nanowires. The catalytic activities of the Ag/Au-SiO2 nanowires to the reduction of 4-nitrophenol(4-NP).In the presence of sodium borohydrid(NaBH4).The Ag/Au-SiO2 nanowires exhibited high catalytic activity to the reduction of 4-NP, rapid reaction, reaction process in line with the first order kinetics process, the stability of the catalytic is well.(3) We report herein a method for the ultra-trace detection of TNT on p-aminothiophenol-functionalized silver nanoparticles coated on silicon oxide nanowires based on surface-enhanced Raman scattering(SERS).The method relies on p-donor-acceptor interactions between the p-acceptor TNT and the p-donor p,p’-dimercaptoazobenzene(DMAB), with the latter serving to cross-link the silver nanoparticles deposited on the silicon oxide nanowires. This system presents optimal imprint molecule contours, with the DMAB forming imprint molecule sites that constitute SERS “hot spots”.Anchoring of the TNT analyte at these sites leads to a pronounced intensification of its Raman emission. Our experiments show that TNT can be detected quickly and accurately with ultra-high sensitivity, selectivity, reusability, and stability. The results reported herein may not only lead to many applications in SERS techniques, but might also form the basis of a new concept for a molecular imprinting strategy.