Metallic nanoparticles are becoming increasingly interesting in nanoscience and technology due to their unique optical, electrical and catalytic properties. The high surface-to-volume ratios of nanoparticles lead to dramatic changes in their properties. As the size and the dimension of particles are reduced, their electronic properties change drastically, because the density of states and the spatial length scale of the electronic motion are reduced with decreasing size. Therefore, the search for new methods of мetallic nanoparticles synthesis is relevant.
Many methods have been reported for the preparation of nanoparticles, such as laser irradiation, sonochemical deposition, photochemical reduction, electrochemical method and chemical reduction of metal salts. Plasmas discharge are widely used to modify the surface properties of solid state materials.
The contact non-equilibrium plasma offers enhanced opportunities over solution chemistry for synthesis new nanomaterials and tailoring their functional properties. The use of contact nonequilibrium plasma and aqueous electrolytes system (low-temperature glow discharge electrolysis), when the cathode is in a liquid phase and the anode is at some distance from the liquid surface, makes it possible to carry out nonequilibrium oxidation processes in the liquid being treated. In the liquid media the oxidation processes occur which cannot be realized by using conventional electrolysis or by the action of arc-crown-, townsend- or barrier-discharge plasma on the liquid.
We report a simple method for preparation of silver nanoparticles by using polymer polyvinyl alcohol (PVA) as a stabilizing agent by usage contact non-equilibrium plasma. PVA was found to be a very efficient stabilizer to prevent aggregation of Ag clusters. The effects of precursor and polymer concentration and of the discharge current on the particle formation process are analysed. The morphology and optical properties of the synthesized metallic nanoparticles are characterized by transmission electron microscopy (TEM) and ultraviolet–visible spectroscopy. The UV–vis spectroscopy revealed the formation of silver nanoparticles by exhibiting surface plasmon absorption maxima at 410 nm. The metal prepared through this method are highly stable and do not show any sign of agglomeration even after storage for months.
The antimicrobial activity of synthesized nanoparticles against strains of four different bacteria (Bacillus cereus, Escherichia coli, Staphylococus aureus, Proteus vulgaris), that are commonly found in water has been studied. The results indicate that such particles have potential applications in biotechnology and biomedical science.