Synthesis And Characterization Of Vanadium Oxides Loaded Mesoporous Titanium Dioxide

Because of its high photocatalytic activity, thermal stability and high corrosion resistance, since Fijishima and Honda discovered the phenomenon that hydrogen could be generated from water by TiO2 electrode in 1972, TiO2 has been at the heart of the study of photocatalytic technology. Another significant influence to TiO2 was the synthesis of mesoporous materials. Due to nano-sized porous structure, mesoporus TiO2 photocatalytic technology has much broader application prospects. However its narrow spectral response range, low optical quantum yield and harsh conditions of use severely limit its large-scale application. It was reported that doping TiO2 with transition metal is an effective approach to improve the photocatalytic activity of TiO2. So this dissertation studied the effect of V2O5 loaded on the photocatalytic activity of mesoporous TiO2. The as-prepared composites were characterized by modern testing methods. The results and conclusions are listed as follows:The mesoporous TiO2 prepared based on the generalized liquid crystal template mechanism possesses particle morphology and worm-like pores, its specific surface area, pore volume and average pore size are 158.7 m2/g,0.095cm3/g and 5.5 nm, respectively. Adding phenolic resin in the synthesis process could limit the hydrolysis rate of titanium dioxide source and the grown up of titanium dioxide. And the exist of carbon could contribute to the formation and retention of worm-like mesoporous structure. The mesoprous TiO2 prepared based on the "Acid-base pairs" theory also possesses particle morphology and its specific surface area, pore volume and average pore size are 137.9 m2/g,0.223cm3/g and 5.9 nm, respectively.V2O5 loading to the two kinds of mesoporous TiO2 was via impregnation and ultrasonic method. It was shown that the particle morphology of the mesoporous TiO2 host was well retained in the composites. The impregnation and ultrasonic method could make the V2O5 well dispersed on/into the TiO2 host. V2O5 loading makes the absorption edge red-shift and enhances absorption intensity of the composites. Because of the polarizability effect of V to O in the composites, the band-gaps of the composites decrease. The two kinds of composite achieve much higher removal rate of the dye than their host in the experiment of characterization of photocatalytic activity of the composites. The mechanism of photocatalyse crystal violet of the two composites is basically the same:the mechanism of demethylation is dominant at the initial stage while the mechanism of damaging the conjugate structure becomes the dominant factor with the increase of irradiation time. In general, mesoporous V2O5/TiO2 composites have a promising application in the environment protection in the future.