Li-Li Ma

Template-free synthesis of BiVO4 nanostructures: II. Relationship between various microstructures for monoclinic BiVO4 and their photocatalytic activity for the degradation of rhodamine B under visible light

The shape-controlled synthesis of nanostructured materials has opened up new possibilities to improve their physical and chemical properties. In this work, new types of monoclinic structured BiVO4 with complex morphologies, namely flowerlike, disclike, tubelike and platelike shapes, have been synthesized in a binary green solvent (water and ethanol) through controlling reaction conditions such as solvent, pH value, concentration of precursors and reaction temperature. The morphology of BiVO4 can transform from three-dimensional (3D) flowerlike superstructures and hexagonal-prismatic nanotubes to two-dimensional (2D) platelike and disclike structures. UV-vis absorption spectra show that all of the prepared nano- and microstructures can respond to visible light and the optical properties of BiVO4 samples are relevant to their structures. More importantly, the photocatalytic activities of various BiVO4 samples are strongly dependent on their morphology for the degradation of rhodamine B (RhB) under visible-light irradiation. The 2D (disclike and platelike) BiVO4 demonstrates better photocatalytic activity than 3D and bulk BiVO4. Among the nano- and microstructures, the nanoplate BiVO4 exhibit the highest photocatalytic activity for degradation of organic pollutants. Additionally, it is found that the different microstructure of BiVO4 leads to the different degradation route for organic compounds of RhB. The reasons for the differences in the photocatalytic behavior for these BiVO4 nanostructures are further discussed. The relationship between the microstructure and the photocatalytic activity for BiVO4 may give clues for the preparation of photocatalysts with high activity based on material morphology design. Moreover, the prepared 2D BiVO4 can be a good photocatalyst used in environmental pollution control.

Atomistic study on twinning of Cu2O quantum dots

Cu2O nanoparticles are investigated at atomic scale by high-resolution transmission electron microscopy. It is found that growth {111} twinning is the most common type of defects in these nanoparticles. The atomic structure of the twinning boundaries is determined referring to the detailed image simulations based on the structure model refined by first-principles calculation. The twin boundary plane is along a {111} oxygen plane and the twinning shows a crystallographic relation with a symmetry operation of 180° rotation around a ⟨111⟩ axis perpendicular to the plane. The effect of the twinning on the stability of the particles is discussed.

Synthesis and Characteristic of Cuprous Oxide Nano-Whiskers with Photocatalytic Activity under Visible Light

A novel Cu2O nano-whiskers with diameter of 6 ~ 12nm has been synthesized with the method of chemical deposition by adding surfactant cetyltrimethylammonium bromide (CTAB) as a template. The structure of the nano-whiskers has been characterized with XRD, SAED, TEM and XPS. The results show that the nano-whiskers exhibit a well crystallized 1D structure about 300 nm in length, and they are self-assembled by Cu2O quantum dots. Under visible light, the degradation efficiency of p-chloronitrobenzene with the Cu2O nano-whiskers as photocatalyst can reach 85.8%.

Cu2O nanorods with large surface area for photodegradation of organic pollutant under visible light

Cu2O nanorods with extraordinary large surface area are synthesized by polyol method successfully. Their photocatalytic property is evaluated by the photodegradation of brilliant red dye under visible light irradiation. For comparison, Cu2O nanocubes are synthesized and evaluated with photocatalytic property as well. The results show that the photocatalytic activity of the Cu2O nanorods is more than one time higher than that for Cu2O nanocubes under visible light. Additionally, the structure of the Cu2O nanorods is very stable and they can not be oxidized to CuO even during the photocatalytic reaction process. It is noticeable that this kind of Cu2O nanorods has remarkable large surface areas 47.6 m2/g, which is about forty times as large as that for as-prepared Cu2O nanocubes and it is also three times larger than that for the reported porous Cu2O nanoparticles. The large surface area of Cu2O nanorods leads to its higher adsorption ability to the brilliant red dye and excellent high photocatalytic activity under visible light. Since Cu2O nanorods are very stable and have high photocatalytic activity under visible light, they are expected to be used in photocatalytic oxidation technology practically in the future.