Kaixun Huang

Controlled growth of oxygen-deficient tin oxide nanostructures via a solvothermal approach in mixed solvents and their optical properties

SnO2 nanostructures such as flower-like nanorod clusters, nanorods with arc or ring hierarchical structures, and individual nanorods were obtained via a solvothermal approach in mixed solvents of ethylenediamine and distilled water. By just simply adjusting growth parameters such as the volume ratio of the two kinds of solvents and dosage of NaOH, the size and hierarchical structures of SnO2 crystals could be easily varied. X-ray diffraction patterns revealed the as-prepared products to be pure tetragonal SnO2 with rutile structure. The energy-dispersive x-ray spectroscopy analysis displayed evidence of nonstoichiometry, indicating that a high concentration of oxygen vacancies exist in the nanorods. High-resolution transmission electron microscopy images revealed that the obtained nanorods exhibited preferential growth along [] and many structural defects existed in the nanorods. The crystal growth mechanism of the SnO2 nanostructures is discussed. Their size-dependent optical properties including UV–vis absorption spectra and room-temperature photoluminescence spectra were also studied.

Rapid and Efficient Removal of Cationic Dyes by Magnetic Chitosan Adsorbent Modified with EDTA

A novel magnetic EDTA–modified chitosan/SiO2/Fe3O4 adsorbent (EDCMS) was employed to remove cationic dyes from aqueous solutions. EDCMS exhibited rapid, efficient, and recyclable adsorption properties for crystal violet (CV) and methylene blue (MB) at pH 5.0-10.0. The adsorption preferably followed the pseudo-second kinetic and the Langmuir isothermal models with an exothermic nature, and the Langmuir maximum capacities reached 227.3 and 138.9 mg g−1 for CV and MB, respectively. Furthermore, EDCMS exhibited much high removal efficiency for both dyes and heavy metal ions in the bi–pollutants system containing low concentrations of heavy metal ions.

Photocatalysis of several organic dyes by a hierarchical Ag 2 V 4 O 11 micro–nanostructures

Hierarchical Ag2V4O11 nano-protuberance-assembled submicrofibers have been successfully synthesized through a facile and surfactant-free hydrothermal strategy. Morphology and microstructures of as-fabricated products are carefully examined using TEM, SA-ED, HRTEM, FE-SEM, XPS and X-ray diffraction. A possible growth mechanism of the as-obtained Ag2V4O11 hierarchical submicrofibers is proposed by a time dependent experiments and the dosage of Ag. The as-prepared Ag2V4O11 products are further regarded as a kind of photocatalyst for the catalytic degradation of three toxic organic dyes, methyl blue (MB), methyl orange and rhodamine blue. Radical trapping experiments have been applied to confirm the photoreaction mechanism. Compared with N-doped TiO2 and P25, the catalyst Ag2V4O11 prepared at 24xa0h reaction time exhibited much higher photocatalytic activity for MB degradation under visible-light illumination. It was ascribed to the formation of superoxide radicals species, and hierarchical structure. The use of ESI-MS analyses showed that the MB dye molecules were broken up by the action of the Ag2V4O11 photocatalyst, indicating the occurrence of a mineralization process. Additionally, kinetic results showed that the degradation process follows Langmuir–Hinshelwood (L–H) first-order kinetic reaction.