| In this dissertation, three kinds of works had been done, as:Firstly, an electro-assisted visible light photocatalytic system was designed for photodegradation of pollutants. AgCl/NPG (nanoporous gold) thin films were prepared via selectively electrochemical corrosion method. The films could effectively decompose methyl orange (MO) dye in aqueous solution which contained a little excess of Ag+ ions under visible light illumination. MO was usually used as a model water pollutant. The visible light induced activity could be ascribed to the self-sensitization of AgCl crystals. The reduced silver species produced during the photooxidation of MO dye could be electrochemically reoxidized by anodic polarization of the AgCl film. Therefore, AgCl crystals were not consumed during the reaction process and they could be used as a visible light photocatalyst in the studied system.Secondly, a metastable porous sheet-likeβ-Bi2O3 was fabricated by the thermal decomposition of bismuth acetate at a relative low temperature. The catalysts were characterized by XRD, TEM, SEM, BET and DRS, and the photo-catalytic activity was evaluated by degrading organic pollutants. The results showed that pure tetragonalβ-Bi2O3 samples could be obtained at 300℃, while increasing the thermal treatment temperature to 350℃or to longer time, the product was a-Bi2O3. The TEM and SEM results revealed that the samples were sheet-like with pores at the size of ca. 30 nm. The UV-Vis spectra results showed that the samples had obvious photoadsorption in visible light region, and the band gap (Eg) was 2.72 eV. Theβ-Bi2O3 samples exhibited very excellent photocatalytic activity for the degradation of methyl orange, rhodamine B and 4-chloropheno (10 mg L-1) under visible light. While 0.05 g catalysts were used, these three kinds of organic pollutants could be degraded in less than 2,2 and 4 hours, respectively. The excellent photo-catalytic performance was due largely to the high BET surface area, and nano-structure. Thirdly, Ti-Bi alloys of different ratios were eroded in nitrid acid for different time, and then were annealed at different temperatures. Finally, series of photocatalysts, such as bismuth titanate, TiO2 andβ-Bi2O3 were prepared by dealloying. The catalysts were characterized by XRD, SEM and EDS, and the photo-catalytic activities were evaluated by degrading organic pollutants in aqeous solutions. The results revealed that when Ti:Bi= 1:2, the erosion time was 5,15,20 and 30 min, and after being heat treated at 500℃, the products were a-Bi2O3, a-Bi2O3, the mixture of a-Bi2O3 and TiO2, and relative pureTiO2, the poweder particles were at the diameter of ca.50 nm. After being heat treated at 600℃, the product was bismuth titanate, and the power size increased to 100 nm. While Ti:Bi= 1:5, the erosion time was 25 min,40 min and 24 h, and after being heat treated at 500℃, the products wereβ-Bi2O3,a-Bi2O3 and relative pureTiO2, the poweder particles were at the diameter of ca.30 nm. After being heat treated at 600℃, similarly the product was bismuth titanate, and the power size increased to 100 nm, too. Among all the catalysts made above,β-Bi2O3,TiO2 and bismuth titanate exhibited a better photocatalytic activity.
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