Fabrication and characterization of Fe_3O_4@SiO_2@TiO_2@Ho nanostructures as a novel and highly efficient photocatalyst for degradation of organic pollution

In this work we synthesize a novel and highly efficient photocatalyst for degradation of methyl orange and rhodamine B. In addition, a new method for synthesis of FeO@SiO@TiO@Ho magnetic core-shell nanoparticles with spherical morphology is proposed. The crystal structures, morphology and chemical properties of the as-synthesized nanoparticles were characterized using Fourier transform infrared spectroscopy（FT-IR）, scanning electron microscopy（SEM）, transmission electron microscopy（TEM）, energy dispersive X-ray（EDS）, X-ray diffraction（XRD）, UV–vis diffuse reflectance spectroscopy（DRS） and vibrating sample magnetometer（VSM） techniques. The photocatalytic activity of FeO@SiO@TiO@Ho was investigated by degradation of methyl orange（MO） as cationic dye and rhodamine B（Rh B） as anionic dye in aqueous solution under UV/vis irradiation. The results indicate that about 92.1% of Rh B and78.4% of MO were degraded after 120 and 150 min, respectively. These degradation results show that FeO@SiO@TiO@Ho nanoparticles are better photocatalyst than Fe3O4@Si O2@TiO 2@Ho for degradation of MO and Rh B. As well as, the catalyst shows high recovery and stability even after several separation cycles.

Facile preparation of Nd2Zr2O7–ZrO2 nanocomposites as an effective photocatalyst via a new route

NdZrO–ZrOnanocomposites were prepared via a facile process with propylene glycol as novel connecting agent and benzene tricarboxylic acid as a new complexing agent. The as-obtained NdZrO–ZrOnanocomposites were characterized by transmission electron microscopy（TEM）, UV–vis diffuse reflectance spectroscopy, energy dispersive X-ray microanalysis（EDX）, Fourier transform infrared（FT-IR）spectroscopy, field emission scanning electron microscopy（FESEM）, and X-ray diffraction（XRD）. According to the morphological studies of the as-synthesized nanocomposites, it was found that the shape and particle size of NdZrO–ZrOnanocomposites depended on the space-filling template type, dosage of space-filling template and tricarboxylic acid as complexing agent. NdZrO–ZrOnanocomposites with different shapes and grain sizes have been synthesized. The photocatalytic behavior of as-produced NdZrO–ZrOnanocomposites was also investigated through photodegradation of methylene blue dye and 2-naphthol as water pollutants.

微波法制备纳米结构铬酸锌的磁学和光学性能(英文)

采用微波法制备纳米结构铬酸锌(Zn Cr2O4)。结果表明,经700°C退火后Zn Cr2O4为晶型良好的尖晶石结构。研究反应时间和微波照射功率对Zn Cr2O4晶粒尺寸和形貌的影响。分别采用X射线衍射(XRD)、扫描电镜(SEM)、能量分散X射线(EDX)、透射电镜(TEM)、漫反射光谱(DRS)、光致发光(PL)光谱、傅里叶红外光谱(FTIR)等技术及振动样品磁强计对所合成的Zn Cr2O4样品进行表征。由漫反射光谱(DRS)计算得到Zn Cr2O4纳米结构的光带能隙为3.50 e V,光致发光光谱分析也证实了该结果。

共沉淀法制备BaMoO_4微米和纳米晶的形貌和光致发光(英文)

通过共沉淀法制备钼酸钡(Ba Mo O4)微米和纳米晶。采用水作为溶剂可得到八面体状的纳米结构。利用X射线衍射、X射线能谱显微分析和傅里叶变换红外光谱对这些纳米晶结构进行表征,使用扫描电镜观察其尺寸和形貌,通过室温下的紫外-可见反射光谱和光致发光测量研究其光学性能。研究温度、溶剂、表面活性剂和钡源对可控形貌的影响,发现这些参数都极大地影响最终产物的形貌、颗粒尺寸和相。

通过简单微波法使用新型硫化剂制备HgS纳米颗粒的结构与光谱表征（英文）

通过简单的微波反应,使用一种新型的前驱体复合物[Hg(C_(13)H_(11)NSO)_2]^(2+),制备具有不同形貌和颗粒尺寸的晶体汞硫化物(HgS)。通过X射线、扫描电镜、紫外-可见光谱对产物进行表征,获得了具有不同尺寸的汞硫化物纳米结构。研究前驱体浓度、溶剂种类、微波时间和功率对产物尺寸和形貌的影响。结果表明:溶剂种类和微波功率极大地影响HgS的最终尺寸。乙二醇是合成细小颗粒HgS的最佳溶剂,制备具有尺寸分布均匀的HgS纳米颗粒的最佳功率是900 W。通过紫外-可见光谱计算出HgS纳米颗粒的带隙是3.2 eV,这相对于块体样品2 eV的带隙蓝移了1.2 eV。

A controllable hydrothermal method to prepare La(OH)_3 nanorods using new precursors

Using the hydrothermal method, lanthanum hydroxide nanorods were synthesized by the reaction of LaC13·7H20, ethyl- enediamine, and hydrazine. According to SEM results, ethylenediamine and hydrazine with pH management could control the parti- cle growth and played an important role in formation of lanthanum hydroxide nanorods. The morphology and microstructure of the obtained products were characterized by X-ray diffraction （XRD） spectra, energy-dispersive X-ray spectroscopy （EDX）, Fourier transformed infi＇ared （FTIR） spectrum, transmission electron microscopy （TEM）, and scanning electron microscopy （SEM）. Further- more, the effects of the molar ratio of the precursors as well as the reaction temperature and time on the morphology and particle size of the products were investigated.

Dysprosium cerate nanostructures:facile synthesis,characterization,optical and photocatalytic properties

A facile approach was developed to prepare Dy2Ce2O7 nanostructures. Dy2Ce2O7 nanostructures were prepared by applying cerium（IV） ammonium nitrate and dysprosium nitrate as Ce and Dy precursors. It was found that the kind of connecting agent, space-filling template and chelating agent were significant factors for the control in shape and size. Transmission electron microscopy（TEM）, X-ray diffraction（XRD）, diffuse reflectance UV-vis spectroscopy（DR-UV-vis）, field emission scanning electron microscopy（FESEM）, photoluminescence spectroscopy（PL） and energy dispersive X-ray microanalysis（EDX） techniques were applied to characterize the Dy2Ce2O7 nanostructures and investigate their optical characteristics. To examine the photocatalytic activity of as-produced Dy2Ce2O7 nanostructures, the photocatalytic degradation of erythrosine dye as water pollutant was carried out. The results of the photocatalytic investigations suggest as-obtained nano-sized Dy2Ce2O7 product as a new, proper and efficient candidate for photocatalytic usages under UV illumination.

Influence of ZrB2 Nanoparticles on the Mechanical and Thermal Behaviors of Carbon Nanotube Reinforced Resol Composite

The present study focuses on the thermal response of carbon fiber-reinforced phenolic composites, where the matrix has been modified with different reinforcements. Two types of materials, multiwalled carbon nanotubes and zirconium diboride （ZrB2）, were used in a new design of mixture to produce the heat- resistant ablative composite system. The CNT/ZrB2/carbon/phenolic nanocomposite （Z/NT-CR） system corresponding to CNT/carbon/phenolic nanocomposite （NT-CR） showed a reasonable decrease in mass loss and the ablation rate as compared to carbon/phenolic composite （CR）. However, substantial drop in two factors was found for Z/NT-CR as compared to carbon/phenolic and NT-CR. Ablation mechanisms for all three composites were investigated by thermal gravimetric analysis in conjunction with micro- structural studies using a field emission scanning electron microscope. The microstructural studies revealed that CNTs acted as an ablation resistant phase for protection against 2000 ℃, and the conversion from ZrB2 to ZrO2 played an important role as an insulator in the performance of char layer in the ablation resistance.

Hydrothermal synthesis of star-like and dendritic PbS nanoparticles from new precursors

Lead sulfide （PbS） nanostructures with different morphologies and particle sizes were obtained via a simple hydrothermal reaction between lead （Ⅱ） salicylate （Pb（Hsal）2） and thiourea （tu）. Reaction products were characterized by means of X-ray diffraction （XRD）, scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, ultraviolet-visible （UV-vis） and Fourier transform infrared （FT-IR） spectroscopy. Morphology of the product, varying from star-like to dendritic, depends on the mole ratio of tu to （Pb（Hsal）2）, pH, and reaction time.

In situ and ex situ synthesis of poly（vinyl alcohol）-Fe304 nanocomposite flame retardants

Application of flame retardants is limited because of environmental requirements. This work introduces conventional magnetic nanoparticles as a new class of nontoxic and effective flame retardant. Fe3O4 enhanced both the thermal stability and flame retardant properties of a poly（vinyl alcohol） matrix. Nanoparticles were synthesized via a simple precipitation reaction without using an inert atmosphere at room temperature. The effects of different precursors and acrylamide on the morphology of the products were investigated. Nanoparticles exhibited a ferrimagnetic behavior at room temperature. To prepare the magnetic nanocomposite, Fe3O4 nanoparticles were added to the poly（vinyl alcohol）. In the presence of a flame, the magnetic nanoparticles remained together, showed resistance to dripping and protected the polymer matrix. Dispersed nanoparticles play a role of a magnetic barrier layer, which slows product volatilization and prevents flames and oxygen from reaching the sample during decomposition of the polymer.

Solvent-less synthesis of zinc oxide nanostructures from Zn(salen) as precursor and their optical properties

ZnO nanoparticles, 10-20 nm in size, were synthesized by heat treatment in air at 500 ℃ for 5 h., using [N,N＇-bis（salicylaldehydo） ethylene diamine]zinc（II）, i.e., Zn（salen）, as precursor, which was obtained by a solvent-flee solid-solid reaction. Heat-treated products were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy. Room temperature photoluminescence spectra of ZnO nanostructures are dominated by green emission attributed to oxygen vacancy related donor-acceptor transition.