Preparation And Characterization Of Silver-Titania Nanoparticles Constructing Block Copolymer Micelles

Becasue of non-toxic, cheap and easy synthesis, titanium dioxide(Ti O2)nano-materials is widely used in solar cells, Nano-catalyst carriers, especially in photocatalysis. In order to achieve high photocatalytic efficiency of the materials, a variety of organic and inorganic compounds have been doped, among them noble metals, since they can en hance the photoelectron-hole separation of risk to significantly improve the catalytic activity of Ti O 2 nano-materials and get attention. This paper aims to take advantage of block copolymers self-assembly synthesizing Ag NPs of core-shell structure and Ag Au NPs of hollow structure. Combining sol-gel preparation methods, Ag-Ti O2 and Ag Au-Ti O2 are synthesized successfully which have high photocatalytic properties.Firstly, block copolymers PS-b-P2 VP with the inorganic components of silver nitrate respectively dissolving in tetrahy drofuran(THF),and block copolymers P2VP-b-PEO with the inorganic components of silver nitrate respectively dissolving in tetrahy drofuran(THF) combining DMF; forming P2VP/Ag+ as the core of the micelle by self-assembled was researched. Experiment takes simple preparation method with UV light irradiation means restoring the Ag+ to Ag, preparing of Ag nanoparticles with core-shell structure without high temperature condition. The size of Ag nanoparticles can be controlled by changing quality of triblock copolymers and silver nitrate.Secondly, combining sol-gel method preparing Ag-Ti O2 nanoparticles, the size and shell thickness of them can be changed by controlling the amount of sol-gel dripping. Tests of photocatalytic degradation o f methylene blue solution with Ag-Ti O2 composite nanoparticles as catalyst are researched. Ultraviolet absorption spectroscopy(UV-Vis spectra) and transmission electron microscope(TEM) show that when adding sol-gel content is 5%SG, Ag-Ti O2 nanoparticles have the best photo-catalytic effect.On the basis of completing the study of Ag-Ti O2 nanoparticles, an in-depth study on the method of preparing bimetallic nanoparticles is explored. Preparation of silver nano-particles with core-shell structure as sacrificial template using simple electronic displacement reaction between gold and silver, Ag Au bimetal composite nanoparticles were prepared. Since Ag+/Ag(0.80Vvs) standard reduction potential is lower than Au Cl4-/Au standard reduction potential(0.99 Vvs standard hydrogen electrode), an electronic substitution reaction will produce when a certain percentage of gold chloride is added to the Ag nanoparticles solution. The majority of Ag nanoparticles will be consumed with the reduction of Au Cl4+. By changing the proportion of gold/silver ratio, the composition and structure of alloy particles can be regulated. Ag Au bimetallic nanoparticles are prepared with a hollow structure at 0.2 percent of gold and silver.Combining with sol-gel method, Ag Au-Ti O2 Nanocomposites were prepared, observed appearance of them by TEM and high-resolution electron microscopy(HRTEM). The photocatalytic activity of Ti O2 nanocomposite materials were researched by photocatalytic degradation of 5mg/L methylene blue solution. Results show that compared to Ti O2 nanocomposite material, Ag Au-Ti O2 composite nanomaterials disply high photocatalytic properties of 42 percent increased.