Preparation And Photocatalytic Properties Of The New Bi Nano Functional Materials

Semiconductor photocatalysis is a comprehensive discipline which combinesphysics, chemistry, material science, biology and engineering science. Recently,photocatalysis has caused great interest in the scientific research area due to itspotential application in the energy utility, environmental purification and realizesustainable development for society. Among lots of photocatalysts, Titanium dioxide（TiO2） has been proved as a widely used photocatalyst for its non-toxicity, cheapnessand stability. However, TiO₂can only be activated by the UV light （occupying around4%of the solar energy）. In order to make the utilization of solar light as sufficient aspossible, doping TiO₂with hybrid atoms and coupling TiO₂with othersemiconductors with low band gaps are usually utilized to extend the light adsorptionedge of TiO₂to visible light range. Recently, Zhao et al. proved the photosensitizationas another approach to extending the photo-response of large band-gapsemiconductors into the visible-light region. Meanwhile, Zhu et al. provedBismuth-based photocatalysts are sensitive in the visible light region since their bandgap are narrow resulted from the hybrid of Bi Bi_6sand O2porbitals. Thus, we mainlyfocus on improving the light utilization and synthesizing visible-light photocatalyststo eliminate these drawbacks. This research work could be described in the followingthree parts:1. Efficient Photosensitized Degradation of High Concentration RhB andRhB-induced Degradation of4-Chlorophenol under Visible Light Irradiation byBiOCl.The BiOCl microsphere photocatalysts were prepared by solvothermal treatment.The as-prepared samples were characterized by X-ray powder diffraction （XRD）, feldemission scanning electron microscopy （FESEM）, transmission electron microscopy（TEM）, N2adsorption desorption （BET）, UV-Vis diffuse refectance spectroscopy（DRS）. The effect of the morphologies, compositions, and physicochemical propertieson the photocatalytic results has been well discussed. Under visible light irradiation（λ>420nm）, BiOCl can be utilized to effectively decompose Rhodamine B （RhB） by photo-sensitization mechanism. Based on detailed study, it was found that the electronfrom the excited dye molecule （RhB） can be directly injected into the conduction bandof BiOCl under visible light irradiation, with the formation of reactive radicals species（HO and O2-） for oxidizing the molecules of RhB and4-CP.2. Self-Assembled3D Architectures of Bi₂TiO₄F₂as a New Durable Visible-LightPhotocatalystA new hierarchical visible-light-driven photocatalyst Bi₂TiO₄F₂was synthesized bya solvothermal method for the frst time. The photocatalyst was characterized byX-ray powder diffraction （XRD）, feld emission scanning electron microscopy（FESEM）, transmission electron microscopy （TEM）, N2adsorption desorption （BET）,UV-Vis diffuse refectance spectroscopy （DRS）. Such hierarchical Bi₂TiO₄F₂microspheres assembled by nanosheets were fabricated via an Ostwal ripeningprocess in the absence of soft templates （surfactants）. Compared to that prepared viahigh temperature solid state method, the Bi₂TiO₄F₂microspheres synthesized with asolvothermal exhibited high photocatalytic performance and durability for thedegradation of rhodamine B （RhB） under visible light （>420nm）.3. Enhancement of Photocatalytic Activity for Bi₂TiO₄F₂with C₆₀modify underVisible IrradiationFullerene (C₆₀) enhanced Bi₂TiO₄F₂hierarchical microspheres were prepared by afacile solvothermal method. Compared to the pure Bi₂TiO₄F₂photocatalyst, the C₆₀/Bi₂TiO₄F₂samples exhibit much stronger photocatalytic performance fordegrading rhodamine B （RhB） and Methyl orange （MO） under visible light irradiation.Such greatly enhanced photocatalytic activity maybe ascribed to strong combinationand heterojunctions between C₆₀and Bi₂TiO₄F₂, favorable for charge separation andlight adsorption. Loading C₆₀on Bi₂TiO₄F₂results in a new photocatalytic mechanism（based on photo-generated hvb+and·O2-radicals） different from that of the pureBi₂TiO₄F₂.