| Recently, as people pay more attention to the environmental issues, the study on treatment technology of environmental pollution is fastly developed. The photocatalysis has attracted great interest for its low energy consumption and innocuity. TiO2is the most widely used photocatalyst due to its high catalytic activity, good chemical stability and non-toxicity, etc. However, it is activated only under UV light irradiation because of its large band gap, moreover, the TiO2powder in suspended system was difficult to separate from aqueous solution, and these questions hindered its practical applications. Therefore, the development of new visible light-driven photocatalyst is essential to improve recyclable performance. Due to its nontoxicity and visible-light responsiveness, Bi2WO6exhibits excellent photocatalytic properties for the decomposition of a great variety of organic pollutants in environmental purification applications. However, the high recombination of photo-generated carriers and low adsorption capacity cause low photo quantum efficiency, resulting in the low photocatalytic performance of Bi2WO6. To overcome the drawback of low photocatalytic efficiency brought by electron holes recombination and low adsorption capacity, we mainly introduced the synthesis and the enhanced photocatalytic activity of the Bi2WO6composite, the clay composite and the plasma composite.In this paper, hierarchical structured CaWO4/Bi2WO6composite was successfully synthesized by a facile and low-cost hydrothermal route. The as-prepared composite were characterized by XRD, SEM, TEM, UV-vis DRS, FT-IR, TG-DSC and BET. The relationship between the hierarchical structured, chemical composition and the surface features of the composite was discussed through a various kind’s characterization analysis. The photocatalytic activities of the CaWO4Bi2WO6composite were evaluated for the degradation of Rhodamine B (RhB) dye and4-nitrophenol (4-NP) in aqueous solution under visible-light irradiation (>420nm), which were4.5times and2.5times higher than that of the pure Bi2WO6, respectively. The CaWO4/Bi2WO6composite still showed the high photocatalytic activity after four reaction cycles. On the basis of the calculated energy band positions, the mechanism of enhanced photocatalytic activity for the CaWO4/Bi2WO6composite can be attributed to the effective separation of electron-hole pairs.To further improve the photocatalytic activities of the Bi2WO6, the hierarchically structured a-Fe2O3/Bi2WO6composite was synthesized by a hydrothermal route. The as-prepared samples were characterized by XRD, SEM, TEM, FT-IR, XPS and BET. The a-Fe2O3/Bi2WO6composite exhibited a strong adsorption capability and a higher visible light photocatalytic activity than the pure Bi2WO6for the photocatalytic degradation of acid red G dye or RhB dye. On the basis of the experimental results and calculated energy band positions, the enhanced photocatalytic activity of the composite can be attributed to the hierarchical structure and the coupling effect of a-Fe2O3and Bi2WO6in the composite.To further improve the adsorption capability of the Bi2WO6, the Bi2WO6/rectorite composites were prepared by a sol-gel method. The relationship between the layer structured and the surface features of the composite was investigated by XRD, SEM, TEM, FT-IR, XPS and BET. The results showed that the composites exhibited a strong adsorption capability and a higher photocatalytic degradation activity for4BS dye, which could be attributed to the synergetic effects of the adsorbability of rectorite and the photocatalytic property of Bi2WO6in it.The novel, efficient, plasma photocatalytic materials was also exploring at the last part. The visible-light-responsive Ag-Ag6Si2O7photocatalyst was synthesized using sodium silicate and silver nitrate as raw materials by a facile microwave method or ion-exchange method and subsequently light-induced reduction route. The Ag-Ag6Si2O7spherical composite exhibited a higher visible light photocatalytic activity for the photocatalytic degradation of MB dye in aqueous solution, which was attributed to the surface plasmon and the polarized field of the Ag6Si2O7photocatalyst. The results showed that h+and O2·-were involved as the active species in the photocatalytic reaction. A possible photocatalytic mechanism and the photocatalytic stability were discussed. |
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