Preparation Of Silver Nano-composites And Its Applications

Silver nanoparticles (NPs) can be used as an efficient antibacterial materials, photocatalyst and surface-enhanced Raman scattering-activity substrate, due to its unique properties. Silver NPs can be used as an efficient catalyst due to its high surface area-to-volume ratio, small diameter and high surface energy with surface defects. Ag nanoparticles powerfully antibacterial activities in vary morphology. In particular, the smaller particles leading to their antibacterial performance better than other vary dimensions. Nevertheless, the high surface energy of noble metal NPs often leads to aggregation and thus decreased catalytic and antibacterial activity. To overcome this challenge, many research methods in this paper have been discussed. Furthermore, different structures and morphology of silver nanomaterials as SERS-activity substrate for the detection of pesticide residue has been developed.First, the anatase crystal flower-like TiO2nanosphers has been synthesized in large scale by a facile sol-hydrothermal method. Then, a simple chemical method has been developed for the preparation of titanium dioxide/silver (TiO2/Ag) nanocomposite microspheres by the tyrosine-reduced silver nanoparticles on the surface of the TiO2microspheres under alkaline conditions. The as-prepared TiO2/Ag flower-like nanocomposites has efficient antibacterial capability for Salmonella and Escherichia coli. Meanwhile, TiO2/Ag nanoparticles have excellent catalytic properties for the reduction of organic dyes.The graphite oxide was synthesized by modified Hummers method, adding a certain amount of PEI-Ag+and using sodium borohydride as reducer, graphene/silver (GO/Ag) nanocomposites were prepared by self-assembly method. Then, the SiO2/Ag nanocomposite spheres were prepared by SiO2nanospheres was used as templet, polyvinylpyrrolidone (PVP) was used as dispersing agent and ascorbic acid was used as reducing agent. The results show that the GO/Ag and SiO2/Ag nanocomposites have well and steady antimicrobial property against S.aureus and E.coli. The obvious inhibitory effects against S.aureus and E.coli were observed when concentration of GO/Ag nanocomposite is4mg/mL and15mg/mL respectively. The obvious inhibitory effects against S.aureus and E.coli were observed when concentration of GO/Ag nanocomposite is0.08mg/mL and0.1mg/mL respectively. Meanwhile, SiO2/Ag nanoparticles have excellent catalytic properties for the reduction of organic dyes.Ag nanocubes and single-crystalline Ag nanowires have been synthesized by a rapid sulfide-mediated polyol method. The Ag nanoparticles were prepared by sodium citrate reduction method. The SERS performance of the Ag nanomaterials was characterized by crystal violet (CV) as the probe molecules. The pesticides of paraoxon and thiram were detected by Ag nanocubes as SERS-active substrates. The results show that the detect limit of paraoxon and thiram is low to5×10-8mol/L. The as-synthesized Ag nanowires have a good draw ratio as a built platform for SERS substrates. The EF of Ag nanowires is more than1.2×107for CV probe molecules. The thiram pesticide is detected by SERS, and the detection limit of thiram to1×10-7M. Ag nanoparticles had a good performance when they were used as the SERS-active substrate. Meanwhile, the pesticide thiram can be effectively detected in the process.