Synthesis And Propoties Of Silver-based/Graphene Nanocomposites

Graphene is a kind of two dimensionality plane structure material with excellent mechanical, electrical and optical properties, and huge specific surface area, which can be used as an advanced support for preparation of nanocomposites. The nanocomposites constructed with nanoparticles and graphene sheets present the great potential in widerspread applications such as catalyst, supercapacitor, biological sensor, water purification and so on. The achievement in preparation of multi-functional above nanocomposites is useful to broaden the application field and develop their practical applications. In this dissertation, we study on design and synthesis of multi-functional silver-based/graphene nanocomposites. The effects of experimental conditions on the morphology, size, composition and dispersion of silver-based nanoparticles in such nancomposites were demonstrated. Through these work, we hope to obtain the multi-functional silver-based/graphene nanocomposites, which can be used to achieve the bacteria separation, surface-enhanced Raman scattering(SERS) detection, and antibacterial properties. The main contributions are described as followed:1. Synthesis of silver nanoparticles/reduced graphene oxisde(Ag/r GO) composites. The Ag/r GO nanocomposites were synthesized by ascorbic acid reduction of Ag+/GO precursor using in-suit reduction method, and the graphene oxide(GO) used as supports. The SEM results showed that Ag nanoparticles in nanocomposites prepared under the condition of p H 10, ice bath and mass ratio of 3:1 were uniform distributed on the r GO sheets, and the average size of Ag nanoparticles was 63 nm. This nanocomposite showed the strong SERS property, which can be used as a SERS substructure for detection of Escherichia coli(E. coli) and Staphylococcus aureus(S. aureus). What is more, this nanocomposite also showed the good antibacterial property. The E. coli can be completely killed by Ag/r GO nanocomposite at the concentration of 50 ?g/m L.2. Synthesis of Ag Fe/r GO nanocomposites. The Ag Fe/r GO nanocomposites were synthesized by sodium borohydride reduction of silver nitrate and iron chloride hexahydrate using in-suit reducetion method, and GO used as supports. The results showed that alloyed Ag with Fe have an average size of 12 nm and decorated uniformly on r GO sheets. This nanocomposite has strong SERS activity, which can be used as a SERS substructure to detect E. coli and S. aureus. This nanocomposite also showed the good antibacterial property. At the concentration of 500 ?g/m L, the nhibition zone size was 13.0 mm. Furthermore, the composite has magnetic property. The saturated magnetizing ratio Ms was 6.1 emu/g, and coercivity Hc was 26.6 Oe.3. Synthesis of Ag Fe/PDDA/r GO composite using electrostatic self-assembly method. The positive charged Ag Fe/PDDA nanoparticles were firstly synthesized, and then were self-assembly with GO sheets to form the Ag Fe/PDDA/r GO composites. This composite has strong magnetic property. The saturated magnetizing ratio Ms was 32.0 emu/g, and coercivity Hc was 61 Oe. In solution, the bacteria can be absorbed by this composite, and deposited in magnetic field within 60 min. The bacteria adsorbed in composites can be detected by Raman spectrum. Moreover, this composite also has antibacterial property, which can restrain the growth of absorbed bacteria. At the concentration of 500 ?g/m L, the nhibition zone size was 15.8 mm.