Lingling Wang

Self-assembled 3D BiOCl hierarchitectures: tunable synthesis and characterization

3D hierarchitectures (HAs) of BiOCl composed of 2D nanosheets, which intercross with each other, have been successfully synthesized by a template-free solvothermal method at 160 °C for 12 h. The morphology and compositional characteristics of the 3D HAs were investigated by various techniques. On the basis of characterization results, the growth of such 3D HAs has been proposed as an Ostwald ripening process followed by self-assembly. The growth and self-assembly of BiOCl nanosheets could be readily tuned with the molar ratio of urea to BiCl3·5H2O, which brought different morphologies and microstructures to the final products. The specific surface area and porosity of the 3D hierarchitectured (HAd) BiOCl also were investigated by using nitrogen adsorption and desorption isotherms. UV–vis spectra reveal that the band gap energies of the 3D HAs can be tuned from 3.05 eV to 3.32 eV. The as-prepared 3D HAd BiOCl showed much higher photocatalytic activity than that of the reported in the literature, which was evaluated by the degradation of Rhodamine-B (RhB) dye under ultraviolet light irradiation.

Porous Fluorine-Doped γ-Fe2O3 Hollow Spheres: Synthesis, Growth Mechanism, and Their Application in Photocatalysis

Porous fluorine-doped maghemite(γ-Fe2O3) hollow spheres have been prepared by facile route based on solvothermal reaction and sequential calcinations. The composition and morphology of the as-prepared samples were characterized by various techniques. The SEM and TEM results showed that the as-synthesized products exhibited a spherical morphology with porous hollow structures. Ultraviolet-visible (UV-vis) diffuse reflectance spectra display that the optical performance of γ-Fe2O3 products are related to their structure and the fluorine concentrations. The porous hollow structured fluorine-doped γ-Fe2O3 spheres exhibit ferromagnetic properties with relatively high saturation magnetization at room temperature. According to the experimental results, a formation mechanism of the fluorine-doped γ-Fe2O3 hollow spheres has been presented. Under UV light irradiation, the photocatalytic degradation activities of the as-synthesized fluorine-doped γ-Fe2O3 samples for RhB dye were 2-5 times higher than that of the undoped sample. The prepared fluorine-doped γ-Fe2O3 hollow spheres will also aroused great interest for their application in catalysis, separation technology, sensors, nanotechnology, and biomedical fields.

In situ synthesis of N-doped carbon nanotubes–BiOCl nanocomposites and their synergistic photocatalytic performance

N-Doped carbon nanotube–BiOCl (NCB) nanocomposites were prepared by an in situ growth strategy in liquid ethylene glycol (EG). The prepared samples were characterized by powder X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (DRS), and photoluminescence (PL) emission spectroscopy. The photocatalytic investigations showed that the 2-NCB nanocomposites loaded with 2.0 wt% N-doped carbon nanotubes (CNxNTs) possessed the highest rate constant, which is about 2.5, 3.7, and 1.5 times that of pure BiOCl 3D hierarchical structures, BiOCl/MWCNTs composites, and P25, respectively. The enhanced photocatalytic performance could be attributed to the beneficial microstructure, synergistic effects of coupled CNxNTs–BiOCl nanocomposites, and the high migration efficiency of the photogenerated electrons, which may effectively suppress the charge recombination.

Preparation and photocatalytic properties of SnO 2 coated on nitrogen-doped carbon nanotubes

SnO2 nanoparticles coated on nitrogen-doped carbon nanotubes were prepared successfully via a simple wet-chemical route. The as-obtained SnO2/CNx composites were characterized using X-ray powder diffraction, scanning electron microscopy, and transmission electron microscopy. The photocatalytic activity of as-prepared SnO2/CNx for degradation Rhodamine B under UV light irradiation was investigated. The results show that SnO2/CNx nanocomposites have a higher photocatalytic activity than pure SnO2 and SnO2/CNTs nanocomposites. This enhanced photoresponse indicates that the photoinduced electrons in the SnO2 prefer separately transferring to the CNx, which has a high degree of defects. As a consequence, the radiative recombination of the electron-hole pairs is hampered and the photocatalytic activity is significantly enhanced for the SnO2/CNx photocatalysts.

Enhancement of Photocatalytic Activity on TiO2-Nitrogen-Doped Carbon Nanotubes Nanocomposites

TiO2-nitrogen-doped carbon nanotubes (TiO2-CNx) nanocomposites are successfully synthesized via a facile hydrothermal method. The prepared photocatalysts were systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and thermogravimetric and differential scanning calorimetry analyses (TGA-DSC). The results show that the TiO2 nanoparticles with a narrow size of 7u2009nm are uniformly deposited on CNx. The photocatalytic activity of the nanocomposite was studied using methyl orange (MO) as a model organic pollutant. The experimental results revealed that the strong linkage between the CNx and TiO2 played a significant role in improving photocatalytic activity. However, the mechanical process for CNx and TiO2 mixtures showed lower activity than neat TiO2. Moreover, TiO2-CNx nanocomposites exhibit much higher photocatalytic activity than that of neat TiO2 and TiO2-CNTs nanocomposites. The improved photodegradation performances are attributed to the suppressed recombination of electrons and holes caused by the effective transfer of photogenerated electrons from TiO2 to CNx.

Three-dimensional lupinus-like TiO2 nanorod@Sn3O4 nanosheet hierarchical heterostructured arrays as photoanode for enhanced photoelectrochemical performance

A novel photoelectrode of three-dimensional (3D) lupinus-like TiO2 nanorod@Sn3O4 nanosheet hierarchical heterostructured arrays (TiO2@Sn3O4 HHAs) on a transparent F-doped SnO2 glass substrate was designed and fabricated by a two-step solvothermal growth process. Photoelectrochemical (PEC) measurements showed that the 3D lupinus-like TiO2@Sn3O4 HHAs photoelectrode displayed enhanced photocurrent density (3-fold increase with respect to that of pure TiO2), improved conversion efficiency, more negative onset potential (from -0.13 to -0.33 V vs normal hydrogen electrode), and higher light on/off cycle stability. The improved PEC properties may be ascribable to the enhancement of light harvesting and large contact area with the electrolyte by increased surface area as well as improvement of charge transfer and collection through the synergistic effects between band structures and morphology.

Facile Fabrication of Platinum Nanoparticles Supported on Nitrogen-doped Carbon Nanotubes and Their Catalytic Activity

A facile impregnation method under mild condition is designed for synthesis of highly dispersed Pt nanoparticles with a narrow size of 4–7 nm on nitrogen-doped carbon nanotubes (CN x ). CN x do not need any pre-surface modification due to the inherent chemical activity. The structure and nature of Pt/CN x were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive spectroscopy spectrum. All the experimental results revealed that the large amount of doped nitrogen atoms in CN x was virtually effective for capturing the Pt(IV) ions. The improved surface nitrogen functionalities and hydrophilicity contributed to the good dispersion and immobilization of Pt nanoparticles on the CN x surface. The Pt/CN x served as active and reusable catalysts in the hydrogenation of allyl alcohol. This could be attributed to high dispersion of Pt nanoparticles and stronger interaction between Pt and the supports, which prevented the Pt nanoparticles from aggregating into less active Pt black and from leaching as well.

Self-assembled spherical palladium/HMS nanocomposites and their catalytic application

A novel palladium catalyst immobilised the mesoporous molecular sieve Hexagonal Mesoporous Silica (HMS) was prepared via a self-assembly process. The catalytic activity and recycle ability of the spherical palladium/HMS nanocomposites were examined for the Heck reaction. Palladium nanoparticles incorporated into HMS are characterised by X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). The morphology of HMS is predominated with spheres, and Pd nanoparticles are randomly distributed throughout the entire silica framework without severe agglomeration. The heterogeneous catalyst is proved to be an active and reusable catalyst in the coupling of ethyl acrylate with aryl halides because of combination, the advantages of stabilising agent and mesoporous silica support.