Xiaodan Yang

Precursor-induced fabrication of β-Bi2O3 microspheres and their performance as visible-light-driven photocatalysts

Flower-like β-Bi2O3 microspheres with high specific surface area and excellent visible-light-driven photocatalytic activity (for degradation of Rhodamine B) were successfully synthesized via a facile hydrothermal process and subsequent calcination. By precisely adjusting the hydrothermal conditions, the composition and morphology of the microspherical precursors could be well controlled, so that upon further optimized calcination of the precursors, the selective formation of the monoclinic α-Bi2O3 and tetragonal β-Bi2O3 with three dimensional (3D) hierarchical architectures could be achieved. These tetragonal β-Bi2O3 microspheres with an average diameter of 3 μm were constructed by nanoflakes with an average thickness of 50 nm, which, as far as we know, is the first reported result on the 3D hierarchical architectures of tetragonal β-Bi2O3. Its flower-like microspherical architecture made the tetragonal β-Bi2O3 possess not only much improved specific surface area but also a narrower band gap, which significantly enhanced its visible-light-driven photocatalytic activity for the degradation of Rhodamine B (RhB). To further optimize the synthetic conditions and realize the controllable synthesis, the formation mechanism for the morphologies and polymorphs of the Bi2O3 microspheres was discussed in detail.

Low-temperature hydrothermal synthesis and structure control of nano-sized CePO4

The nanostructured CePO4 with hexagonal and monoclinic phases were controllably synthesized through a hydrothermal route at a low temperature of 100 °C by simply varying the reactant PO4/Ce molar ratio. By analyzing the synthesis procedure and product structures, the formation mechanism of the CePO4nanostructures was proposed. The luminescent properties of CePO4 with different structures and morphologies have been studied and compared. The obvious blue shift of the strongest excitation peak of the monoclinic CePO4 compared with the hexagonal CePO4 could be observed in their luminescence spectra. With the cycling use of phosphoric acid, the low-cost preparation of CePO4 could be achieved. Furthermore, this synthesis strategy will open a novel approach to rare earth phosphates with multiple structures.

Microstructure construction and composition modification of CeO2 macrospheres with superior performance

Macro/nano-composite CeO2 spheres with variable diameters of 30–300 μm assembled from nanoparticles of 5–8 nm were synthesized through the calcination of the well assembled spherical Ce(COOH)3 precursor. The controlled hydrolysis of DMF is the key factor for both the crystallization of Ce(COOH)3 and the formation of its macrospheres. These hierarchical CeO2 macrospheres possess pretty high specific surface areas of up to ∼190 m2 g−1 and show an excellent ability to remove Cr(VI) from aqueous solution. Moreover, when substituted with Bi(III), the oxygen storage capacity (OSC) of these CeO2 spheres could be improved sharply to 3243.75 μmol [O] g−1. With an easy-to-manipulate macroscale spherical morphology, these materials are easily recycled. This synthesis opens a promising route for high performance metal oxides.