Preparation, Modification Of Bi₂WO₆ Photocatalyst And Their Photocatalytic Performance In Low Concentration Gas-phase Toluene Degradation

Novel photocatalysts Bi2WO6 have intrinsic visible-light absorbtion ability due to its narrow band gap, and become one of the current topics. However, there are still some drawbacks, such as:complex preparation methods, highly combination rate of e-/h+, lower photocatalytic activity. In this paper, Bi2WO6 photocatalyst was prepared by liquid phase method. The BioWO6 photocatalyst was then doped with transition metal Fe-ions and modified with Pt species, respectively. The photocatalytic activity of the samples was evaluated using photocatalytic oxidation of toluene.(1) Bi2WO6 nanosheets photocatalyst were synthesized via a non-surfactant hydrothermal process. And it was modified with Fe-ions by wetness impregnation treatment to prepared Fe-Bi2WO6 photocatalyst. The photocatalytic activity of the catalyst was evaluated by the photodegradation of low concentration gas phase toluene.The result showed that the optimized content of Fe-ions was at 0.1 wt.%. The characterization analysis indicated that Fe-ions were mainly uniformly distributed on the surface of Bi2WO6 nanosheets. It also showed moderate Fe-ions acted as both electron and hole trap, reduced the e-/h+ pair recombination rate, improved the photocatalytic activity. Circled photocatalytic activity test indicated that the devitalization of the catalyst could mainly attribute to the migration of Fe3+-ions to bulk phase and the accumulation of by-product.(2) PtCl4/Bi2WO6 nanojunction photocatalyst was produced by a one-step hydrothermal approach. The result showed that PtCl4/Bi2WO6 nanojunction revealled excellent photocatalytic activity and photochemical stability.The optimized content of Pt species was 1.0wt.%. The characterization analysis indicated that the nanojunction between PtCl4 and Bi2WO6 enhanced the absorbtion of visible light and the separation rate of photocarrier, improved its visible light photocatalytic pefermance.(3) The novel three-component Pt/Bi2WO6/PtO nanjunction system was synthesized by wet-chemical method. It was suggested that PtO (p-type semiconductor) increased the absorbtion of visible light, the p-n type nanojunction between PtO and Bi2WO6 strengthened the separation of e-/h+. The formation of Schottky barrier between Pt particle and Bi2WO6 promoted the migration and utilization of electron, and contributed to the separation of e-/h+. Furthermore, the effect of pH during the preparation process on the photocatalytic performance of system was investigated. It was found that the pH changed the ratio of Pt particle and PtO, which existed on the surface of Bi2WO6, thus influenced the separative efficiency of photocarrier.