Tan Lianjiang

Preparation of LaTiO2N photocatalyst with a large surface area

In this following communication, a new nanocrystalline photocatalyst LaTiO2N with a large surface area of 27.5 m2/g was synthesized by nitridation of amorphous La2O3/TiO2 composite powder at 900°C for 8 h using NH3 as the reactant gas, and the co-precipitate method was used to synthesize the high active amorphous La2O3/TiO2 composite powder. The X-ray powder diffraction (XRD) and transmission electron microscopy (TEM) results revealed that the as-prepared LaTiO2N nanocrystals had a mean diameter of about 30 nm. With increasing the nitrided temperature from 700°C to 900°C, it can be seen that the color of the oxynitride vary from yellow to red, and the specific surface area of the sample became lower since the high temperature can lead to the coalescence and aggregation of the nanoparticles. Both a higher nitridation temperature and a longer nitridation time can lead to a higher nitrogen content of the oxynitride. The TEM of the oxynitride obtained at 700°C, 800°C revealed some voids are in the oxynitride nanoparticles, which may be attribute to the density difference between oxide and oxynitride. The band gap energy of LaTiO2N was estimated to be 2.1 eV for its absorption band was founded to extend to 600 nm, it indicated that the synthesized oxynitrides displayed good light absorption properties not only in the ultraviolet light but also in the visible light region. Its high specific surface area and narrow band gap energy may guarantee photocatalytic activity under visible light excitation.

基于“分子胶”的新型两亲性嵌段共聚物 β -CD-PLA的合成及其胶束化

以二重氢键为引导，二硫键连接疏水性聚乳酸（PLA）和亲水性 β -环糊精（ β -CD）合成了嵌段共聚物 β -CD-PLA。采用 1 H-NMR和GPC对嵌段共聚物 β -CD-PLA的结构进行了表征，以芘作为荧光分子探针对嵌段共聚物 β -CD-PLA自组装胶束的性质进行了表征，采用动态光散射纳米粒度仪（DLS）对自组装胶束的粒径进行了测试。结果表明：在二重氢键的引导作用力和碘的氧化作用下，中间体脱去保护基形成双二硫键，形成目标嵌段共聚物 β -CD-PLA，该嵌段共聚物能够在水中自组装形成纳米胶束，临界胶束浓度（CMC）为0.089 mg/mL，在稀溶液中具有良好的稳定性，自组装形成空白胶束的粒径为31 nm，阿霉素盐酸盐（DOX）载药胶束的粒径为42 nm。