Preparation And The Spectral Properties Of Silver Nanoparticles And Their Analytical Application

Chapter 1:Nano-materials have been become one focus in material science due to their unique properties.Having the advantages of easy to get,simple in preparation,low-cost and so on in noble nano-metallic materials,silver nanoparticles material has attracted many researchers.This chapter briefly introduced the defination,properties and applications of nano-materials. The major focus was the current preparation methods of silver nanoparticles and their application in various fields.Chapter 2:The silver nanoparticles were prepared using chemical reduction method in water phase and organic phase,respectively.And they were characterized by ultraviolet - visible absorption spectroscopy(UV-Vis), fluorescence spectroscopy,infrared absorption spectrometry(FT-IR), transmission electron microscopy(TEM) and other means.The experiment results showed that the silver nanoparticles using sodium citrate or sodium borohydride in water phase were smaller,the size of silver nanoparticles was about 20nm and 5nm,respectively.And they were more uniform in shape and having a longer time for preservation,simpler in preparation and easier in operation.The silver nanoparticles prepared in organic phase of DMF were unevener in shape,larger in size,shorter for saving and easier for gathering.Chapter3:A series of factors in preparation of Silver nanoparticles particles were investigated.The influence of polyvinyl pyrrolidone,polyvinyl alcohol and strong electrolytes of sodium halogeneration(NaCl,NaBr and NaI) was characterized by TEM and UV-Vis spectra.It was found that silver particles synthesized by different methods showed the diversity in dispersedness and size.However,there was difference in UV-Vis spectra. The adding of strong electrolyte of sodium halogeneration had distinct effects on the UV-Vis spectra of silver particles especially when they were without protection of PVP and PVA.When the concentration of strong electrolyte of sodium halogeneration achieved a critical value,a abrupt change in UV-Vis spectra of silver nanoparticles was obtained.Chapter 4:This chapter studied the interaction between Silver nanoparticles and methylene blue by UV-Vis spectroscopy and fluorescence spectrometry. It was found that UV-Vis Spectral significantly decreased with the adding of methylene blue in the solution of silver nanoparticles.However,no obvious change of UV-Vis absorption spectra was observed when silver nanoparticles were added into methylene blue solution.In the presence of surfactant of sodium dodecyl sulfate,NaBH4 and methylene blue solution, UV-Vis spectroscopy and fluorescence spectra of methylene blue solution which was added silver nanoparticles was much more significant in decrease and shorter in response time than that not added.The experiment showed that the surface activity of silver nanoparticals was great and the strong physical adsorption of them to methylene blue was existed.Thus,the probe made by silver nanoparticals and methylene blue has a wide promising application in protein detection,DNA analysis,small molecule recognition and so on.Chapter 5:In this chapter,silver nanoparticles film,Ag-SiO₂ composite film and Ag-MCNT composite film were prepared on the slide glass.They were used as a sensitive layer for methane detection.It was found that there was response of the slide glass coated by Ag-SiO₂ composite nanoparticles to CH₄ and N₂ gas,but it was poor in selectivity and repeatability.And the other two films showed no apparent response.Nanomaterials of Ag-SiO₂ used in gas detection were realized.