Preparation And Characterization Of Silver Doped Titanium Dioxide Composite Nanopowder

Semiconductor photocatalytic technology in water and air purification,Solar energy conversion have wide potential application prospect.Since 1972,Fujishima and Honda found TiO2 electrode photodissociation water, titanium dioxide semiconductor optical catalytic materials has been widely studied.Nanosized titanium dioxide is one of most popular environmentally harmonious photocatalysts in this day because of its non-toxicity,physical and chemical stability,high photocatalytic activity,low cost become the most potential semiconductor photocatalytic materials.However,the efficiency of photocatalytic reaction is limited by the high recombination rate of photo-induced electron-hole pairs formed in photocatalytic processes and by the absorption capability to visible light of photocatalysts.Therefore,Numerous studies have been recently performed to improve the efficiency of photocatalytic reactions through various methods broaden spectral response range,improving the quantum efficiencies,this studies include controling crystal shape,doping metal ion into the TiO2 lattice,dye photosensitization on the TiO2 surface,deposition of noble metals and the dual semiconductor compound and so on.In this paper, it introduces the mechanism of the photocatalytic titanium dioxide,Modified sol-gel process route,preparation of the metals Ag doping nano TiO2 photocatalyst and Through a variety of characterization method was used to study the Ag/TiO2 nano photocatalyst preparation process the influencing factors and catalytic activity.First of all, Pure and Ag-doped TiO2 nanoparticle powders were prepared by the sol-gel process, using Ti(OC4H9)4 and silver nitrate as raw materials and the source of silver, respectively, adding mixture of acetic acid to control hydrolysis.It studied the influence factors of titanium dioxide crystal transformation and grain size effect,analyzes the formation mechanism of composite powder.Then,in order to solve the above sol-gel process of preparation nanometer TiO2 particles of dispersion and Ag particles uniform distribution problems.We take the polymer gel route, using Ti(OC4H9)4 as raw material and silver nitrate as silver source, nano-TiO2 and nano-sized Ag/TiO2 particles were prepared via polymer gel process by adding chelating agent acetic acid, surface modification agent 3-aminopropyltriethoxysilane and reducing agent formaldehyde to the reaction system.The nano-powder of TiO2 and Ag/TiO2 were characterized by FT-IR,XRD,TG-DTA, TEM,SEM and UV-Vis-NIR.The results indicate that the composite powders of Ag-doped TiO2 surface modified with 3-Aminopropyltriethoxysilane improve the dispersion of the grains, and silver particles, with average grain diameter of 1nm, are distributed on surface of TiO2 particle of 10～15 nm; Absorption of visible light and heat stability of anatase are improved. Surface modifier in the formation of a compound particle plays a role of bridge, Roasting temperature and roasting time of a sample size and type composition have effect. Research on preparation of samples at different PH value the morphology of influence.Finally, we use the sample preparation degradation of methyl orange solution and found through the APS modification of TiO2 composite nanometer powder Ag/TiO2 the degradation of the best performance.Meanwhile, solution PH value of TiO2 photocatalytic degradation reaction efficiency have influence.