Design, Synthesis And Photocatalytic Activity Of Bismuth-based Photocatalysts With Ionic Liquids

With the development of our society, the problems of energy shortage and environment Pollution affect our living standard. Photocatalytic technology is one kind of green Advanced oxidation technology, which has been widely used in environmental pollutant treatment and energy development. Visible-light-driven photocatalysts with high activity and stability had attracted a great deal of attention. In this paper, it was focused on the synthesis of BiOX visible-light-driven photocatalysts in reactable ionic liquids system. These resulting materials were characterized by XRD,XPS,SEM,TEM,BET,DRS and photocatalytic activity test, the relationship between the structure of the photocatalyst and the photocatalytic activities were also discussed in details.BiOI uniform porous nanospheres and flower-like hollow microspheres with a hole in its surface structures have been synthesized through an EG-assisted solvothermal process in the presence of ionic liquid 1-butyl-3-methylimidazolium iodine ([Bmim]I). The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), nitrogen sorption and diffuse reflectance spectroscopy (DRS). Possible formation mechanism for the growth of hollow microspheres was discussed. During the reactive process, ionic liquid not only acted as solvents and templates but also as I source for the fabrication of BiOI hollow microspheres, and was vital for the structure of hollow microspheres. Additionally, we evaluated the photocatalytic activities of BiOI on the degradation of methyl orange (MO) under visible light irradiation and found that as-prepared BiOI hollow microspheres exhibited higher photocatalytic activity than BiOI nanoplates and TiO2 (Degussa, P25) did. On the basis of such analysis, it can be assumed that the enhanced photocatalytic activities of BiOI hollow microspheres could be ascribed to its energy band structure, high BET surface area, high surface-to-volume ratios and light absorbance.BiOBr uniform flower-like hollow microspheres and porous nanospheres structures have been synthesized through a one-pot EG-assisted solvothermal process in the presence of reactable ionic liquid 1-hexadecyl-3-methylimidazolium bromide ([C16mim]Br). The as-prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and diffuse reflectance spectroscopy (DRS). Possible formation mechanism for the growth of hollow microspheres was discussed. During the reactive process, ionic liquid [C16mim]Br played the role of solvent, reactant and template at the same time. Moreover, the photocatalytic activities of BiOBr flower-like hollow and porous structures were evaluated on the degradation of rhodamine B (RhB) under visible light irradiation. The results assumed that BiOBr porous nanospheres samples showed much higher photocatalytic activity than the conventional method prepared sample and TiO2 (Degussa, P25). The relationship between the structure of the photocatalyst and the photocatalytic activities were also discussed in details, it can be assumed that the enhanced photocatalytic activities of BiOBr materials could be ascribed to a synergetic effect, including high BET surface area, the energy band structure, the smaller particle size and light absorbance.BiOCl uniform flower-like and sphere-like structures have been synthesized through an solvothermal process in the presence of ionic liquid 1-hexadecyl-3-methylimidazolium chloride ([C16mim]C1). The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and diffuse reflectance spectroscopy (DRS). During the reactive process, ionic liquid not only acted as solvents and templates but also as Cl source for the fabrication of BiOCl materials. The influence of the ionic liquid cations and solvothermal solution on the morphology of BiOCl materials was studied in detail. Additionally, the photocatalytic activities of BiOCl crystals on the degradation of rhodamine B (RhB) under visible light irradiation were evaluated. The results showed that flower-like BiOCl structures synthesized with exhibited higher photocatalytic activity than other BiOCl materials and the photocatalytic activities of BiOCl crystals were increased with the increasing alkyl carbon chain of ionic liquid cations.BiOX1/BiOX2(X1, X2=C1, Br, I) uniform flower-like composites have been synthesized through an solvothermal process in the presence of ionic liquid [C16mim]Cl, [C16mim]Br and [Bmim]I. The as-prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and diffuse reflectance spectroscopy (DRS). During the reactive process, ionic liquid acted as solvents, templates and halides source for the fabrication of BiOX1/BiOX2(X,, X2=C1, Br, I) materials. The optical properties of BiOX1/BiOX2(X1, X2=C1, Br, I) were studied studied in detail and the band gaps of the as-prepared composites were estimated to about 2.18,2.89, and 2.39 eV for BiOBr/BiOI, BiOBr/BiOCl and BiOCl/BiOI, respectively. Additionally, the photocatalytic activities of BiOX1/BiOX2(X1, X2=C1, Br, I) crystals on the degradation of rhodamine B (RhB), Methylene Blue (MB) and Methyl Orange (MO) under visible light irradiation were evaluated. The results showed that flower-like BiOX1/BiOX2(X1,X2=C1, Br, I) structures synthesized with exhibited good photocatalytic activity of the three types of dye and the photocatalytic activity of RhB was the best. Bi2WO6 uniform hierarchical nest-like structures have been synthesized through an ionic liquid-assisted hydrothermal method in the presence of 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4). The Bi2WO6 hierarchical structures have an average diameter of about 3-5μm and are assembled by Bi2WO6 nanosheets with size ranging from 18 to 20 nm. The results show that ionic liquid [Bmim]BF4 is vital for the formation of Bi2WO6 nest-like hierarchical structures. The UV-vis diffuse reflectance spectroscopy indicate that Bi2WO6 hierarchical nest-like structures induces a significantly enhanced optical absorbance in the UV-visible region, which is ascribed to multiple scattering within the hierarchical assemblies to the lengthened optical path length for light transporting. Additionally, the photocatalytic activities of Bi2WO6 crystals on the degradation of rhodamine B (RhB) under visible light irradiation were evaluated. The results showed that nest-like Bi2WO6 structures synthesized with exhibited higher photocatalytic activity than Bi2WO6 nanosheets prepared in conventional method.