| Synthesis of Ag/SiO2 nanocomposite materials in a nanoreactor formed by the water-rich adsorption layer on the surface of SiO2 were studied in this dissertation. First, the research, characteristic and application of Ag nanoparticles and nanocomposite materials were reviewed. According to whether nanoreactor was used in the preparation process of nanoparticles, the author divided the preparation methods of nanocomposite materials into two kinds: traditional methods and microscale reaction technology. The author divided microscale reaction technology into soft constraint and hard constraint in terms of boundary properties, and independently generalized its principle, characteristic and application. The advantage and disadvantage microscale reaction technology were also generalized contrasted with traditional methods.Based on the generalization of abroad literatures and research findings, the principle and characteristic of adsorption phase nanoreactor technology were represented detailed, and pointed out the formation of adsorption layer and reaction place were the two most important factors in this technology. Then the aspects which were not discussed deeply and research findings which had been achieved were summarized, and the research orientation and experiment strategies were proposed.Four reaction systems were employed to investigate the effects of adsorbates (L-Ascorbic acid, AgNO3, C6H57Na3, NaOH) distribution between ethanol bulk phase and water-rich adsorption layer. It was found that, with increase of distribution proportion of adsorbates in the water-rich adsorption layer, Ag grain size decreased and Ag dispersion on the surface of SiO2 became more uniform; NaOH was an adsorbate which trended to distribute in adsorption layer, and a set of comparable experiments proved that Ag generation reaction took place in the layer, so the author selected the reaction system with NaOH as adsorbate to study deeply.For the established system the author designed a series of experiments including NaOH concentration, water concentration and temperature experiments to study thepreparation processes with the help of many kinds of analytical methods such as Electrical Conductivity Meter, TEM, XRD, EDAX and UV-Vis spectra. Results showed: (1) with increase of NaOH concentration the content ratio of NaOH between in adsorption layer and in ethanol would decrease after increasing firstly and Ag grain size would increase after decreasing firstly; (2) with increase of water concentration the content of NaOH adsorbed on SiO2 would increase, and Ag grain size would become smaller and its dispersion become more uniform; (3) with increase of temperature the content of NaOH adsorbed on SiO2 would increase, and Ag grain size and Ag appearing time would both change radically from 25°C to 40°C.Based on the discussion about adsorption phase reaction processes including adsorption layer formation, NaOH distribution and Ag generation, it could be concluded that there were three potential reaction zones in the system, and in different reaction zone the mechanism of Ag generation would change, which resulted in change of Ag size. Then the effect mechanisms of NaOH concentration, water concentration and temperature were gained: (1) the change of NaOH concentration would influence the difference of NaOH concentration between in adsorption layer and in ethanol, and the difference determined the reaction zone; (2) the change of water concentration would influence the thickness of adsorption layer, which would determine the reaction zone; (3) the change of temperature would result in the change of adsorption layer thickness, which would change reaction zone.At last, the work in the dissertation was generalized, and the problems which still need to discuss in paper were represented. |
