Template-free synthesis of CdS hollow nanospheres based on an ionic liquid assisted hydrothermal process and their application in photocatalysis

Polycrystalline CdS hollow nanospheres with diameter of about 130 nm have been successfully synthesized in high yield by an ionic liquid (IL) assisted template-free hydrothermal method for the first time. Both the molar ratios of Cd/S precursor in the solution and the reaction temperature play important roles in the formation of the CdS hollow nanospheres. The concentrations of capping agent hexamethylenetetramine (HMT) and polyvinylpyrrolidone (PVP) are also crucial for the morphology and size of the final product. IL was found to be a key component in the formation of CdS hollow structures, because solid spheres were obtained in the absence of IL. A subsequent growth mechanism of hollow interior by localized Ostwald ripening process has been further discussed. Such hollow structures show high photocatalytic ability in the photodegradation of methylene blue.     

单斜晶型钒酸铋空心纳米球的制备及其光催化性能

无需添加任何模板剂,以Bi(NO3)·5H2O和NH4VO3为原料,采用柠檬酸络合法结合热处理的方法成功合成了BiVO4空心纳米球.采用TEM、XRD、TG-DTA、UV-Vis等测试手段对样品的形貌、相结构、光吸收性能进行了表征,以亚甲基蓝染料溶液的脱色降解实验为模型反应考察了样品的光催化性能.结果表明,所制备的BiVO4以单斜晶系白钨矿相存在且具有良好的中空结构,空心球平均粒径为160 nm,空腔直径为10～80 nm.UV-Vis谱图数据表明所制备的BiVO4样品的禁带宽度约为2.26 eV,样品在紫外区和可见区均有较强的光吸收.可见光照射下,亚甲基蓝溶液经BiVO4空心球脱色处理150 min后,脱色率可达到95%以上,COD去除率为73.66%.另外,考察了柠檬酸与铋离子不同摩尔比对空心球形貌的影响,并对BiVO空心纳米球的形成机理进行了探讨.     

Facile fabrication and optical property of hollow SnO2 spheres and their application in water treatment

Hollow SnO(2) spheres with smooth surface have been fabricated by a low temperature template-free solution phase route via self-assembly of small nanocrystalline particles. These hollow spheres have a very thin shell thickness of about 10 nm and are built from SnO(2) nanocrystals of an average size of 5.3 nm. The evacuation behavior of inside-out Ostwald ripening can be used to explain the formation of hollow spheres according to results of time-dependent reactions. The cathodoluminescence spectrum indicates a blue shift of the band gap emission peak of SnO(2), originating from quantum confinement effect due to the nanoscale size of SnO(2) particles. The as-prepared SnO(2) hollow spheres were also found to exhibit excellent performance in wastewater treatment.     

Fe2O3/ZnO/ZnFe2O4 composites for the efficient photocatalytic degradation of organic dyes under visible light

In this study, novel ternary Fe₂O₃/ZnO/ZnFe₂O₄ (ZFO) composites were successfully prepared through a simple hydrothermal reaction with subsequent thermal treatment. The as-prepared products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) analysis, Barrett-Joyner-Halenda (BJH) measurement, and UV–vis diffuse reflectance spectroscopy (UV–vis DRS). The photocatalytic degradation of rhodamine B (Rh B) under visible light irradiation indicated that the ZFO composites calcined at 500 °C has the best photocatalytic activity (the photocatalytic degradation efficiency can reach up to 95.7% within 60 min) and can maintain a stable photocatalytic degradation efficiency for at least three cycles. In addition, the photocatalytic activity of ZFO composites toward dye decomposition follows the order cationic Rh B > anionic methyl orange. Finally, using different scavengers, superoxide and hydroxyl radicals were identified as the primary active species during the degradation reaction of Rh B.     

Non-conductive nanomaterial enhanced electrochemical response in stripping voltammetry: The use of nanostructured magnesium silicate hollow spheres for heavy metal ions detection

Nanostructured magnesium silicate hollow spheres, one kind of non-conductive nanomaterials, were used in heavy metal ions (HMIs) detection with enhanced performance for the first time. The detailed study of the enhancing electrochemical response in stripping voltammetry for simultaneous detection of ultratrace Cd²⁺, Pb²⁺, Cu²⁺ and Hg²⁺ was described. Electrochemical properties of modified electrodes were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The operational parameters which have influence on the deposition and stripping of metal ions, such as supporting electrolytes, pH value, and deposition time were carefully studied. The anodic stripping voltammetric performance toward HMIs was evaluated using square wave anodic stripping voltammetry (SWASV) analysis. The detection limits achieved (0.186 nM, 0.247 nM, 0.169 nM and 0.375 nM for Cd²⁺, Pb²⁺, Cu²⁺ and Hg²⁺) are much lower than the guideline values in drinking water given by the World Health Organization (WHO). In addition, the interference and stability of the modified electrode were also investigated under the optimized conditions. An interesting phenomenon of mutual interference between different metal ions was observed. Most importantly, the sensitivity of Pb²⁺ increased in the presence of certain concentrations of other metal ions, such as Cd²⁺, Cu²⁺ and Hg²⁺ both individually and simultaneously. The proposed electrochemical sensing method is thus expected to open new opportunities to broaden the use of SWASV in analysis for detecting HMIs in the environment.     

Facile synthesis of iron oxide with wormlike morphology and their application in water treatment

A novel and facile synthesis route for the manufacture of transparent and uniform nanocrystalline α-Fe₂O₃ (nc-Fe₂O₃) thin films and equivalent powders with wormlike morphology is reported, utilizing ferric nitrate as the inorganic source and triblock copolymer as the wormlike morphology-directing agent through the evaporation-induced assembly (EIA) method. X-ray powder diffraction (XRD), ellipsometry, thermogravimetry-differential scanning calorimetry (TG-DSC), Raman spectrum, N₂-sorption and scanning electron microscopy (SEM) were used to study the nc-Fe₂O₃ thin films and powders obtained by calcination at different temperatures. The nc-Fe₂O₃ powder samples showed an excellent ability to remove heavy metal ion (Cr(VI)) in water treatment. The possible formation mechanism of the nc-Fe₂O₃ with wormlike morphology was discussed.     

Synthesis,Structure and Characterization of Three Metal Molybdate Hydrates: Fe(H2O)2(MoO4)2·H3O,NaCo2(MoO4)2(H3O2)and Mn2(MoO4)3·2H3O

Three metal molybdate hydrates,Fe(H2O)2(MoO4)2·H3O(FeMo),NaCo2(MoO4)2(H3O2)(CoMo)and Mn2(MoO4)3·2H3O(MnMo),were synthesized by the mixed-solvent-thermal methods and characterized by singlecrystal X-ray...     

Facile synthesis of Co3O4 and Ag/Co3O4 nanosheets and their electrocatalytic properties

The precursors of Co₃O₄ and Ag/Co₃O₄ composites with different Ag contents were synthesized with assistance of (NH₄)₂CO₃ via a facile hydrothermal process. The final samples were fabricated by calcining each precursor at 400 °C according to TG experiment. The as-prepared samples were identified and characterized by thermogravimetric analysis, X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and field emission scanning electron microscopy, respectively. The results showed that the morphology of Co₃O₄ and Ag/Co₃O₄ composites were sheet-like. Ag nanoparticles were dispersed well in the nanosheets. The samples were used as electrocatalysts modified directly on a glassy carbon electrode for p-nitrophenol reduction in a basic solution. The results showed that p-nitrophenol could be reduced at a large peak current but a higher peak potential with Co₃O₄, at lower potentials with Ag/Co₃O₄ composites. Ag/Co₃O₄ composite with 3 % Ag showed more efficiently electrocatalytic activity than other composites. The present method suggested the potential application of Ag/Co₃O₄ composites in electrocatalysis.     

Individual and Simultaneous Voltammetric Determination of Cd(II), Cu(II) and Pb(II) Applying Amino Functionalized Fe3O4@Carbon Microspheres Modified Electrode

Amino‐functionalized Fe₃O₄@carbon microspheres (NH₂?Fe₃O₄@C) were prepared and the electrochemical sensor was constructed using NH₂?Fe₃O₄@C modified glassy carbon electrodes (GCE) to determine toxic heavy metals in aqueous solution. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the structure and phase of NH₂?Fe₃O₄@C. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results indicate that NH₂?Fe₃O₄@C modified GCE possesses large active area and excellent electron transfer. Under optimized electrochemical condition, Cd(II), Pb(II) and Cu(II) were determined using NH₂?Fe₃O₄@C modified GCE. The electrode through amino functionalization exhibits higher sensitivity and lower detection limit toward Cd(II) and Cu(II) due to the acid‐base pairing interaction between the electron‐rich ?NH₂ ligand and the electron‐deficient heavy metal ions. Compared with other similar results reported in the literature, the NH₂?Fe₃O₄@C modified electrode exhibits wider linear response range while with comparable lower detection limit. It also exhibits excellent stability, reproducibility and anti‐interference ability.     

Preparation of core-shell magnetic Fe3O4@SiO2-dithiocarbamate nanoparticle and its application for the Ni2+, Cu2+ removal

A typical superparamagnetic nanoparticles-based dithiocarbamate absorbent (Fe₃O₄@SiO₂-DTC) with core-shell structure was applied for aqueous solution heavy metal ions Ni²⁺, Cu²⁺ removal.     

微米聚苯胺/Fe_3O_4空心球的制备及吸波性能

采用界面聚合和Pickering乳液聚合相结合的方法,以甲苯为软模板,磁性Fe3O4纳米颗粒为稳定剂,十二烷基苯磺酸钠(SDBS)为乳化剂,过硫酸铵(APS)为氧化剂,盐酸(HCl)为掺杂剂,制备了掺杂态聚苯胺/Fe3O4(D-PANI/Fe3O4)空心球.作为比较,在不掺杂盐酸的条件下,制备了本征态聚苯胺/Fe3O4(PANI/Fe3O4)空心球.用透射电子显微镜(TEM)、扫描电子显微镜(SEM)、X射线衍射(XRD)仪、傅里叶变换红外光谱(FTIR)仪、热重分析(TG)仪、振动样品磁强(VSM)计及恒压四探针测试仪对复合材料的形貌、结构、组成和电磁性能进行了表征.结果表明,D-PANI/Fe3O4空心球的直径约为2.8μm,电导率和饱和磁化强度(Ms)分别为2.75×10-2S/cm和54.26 A·m2/kg.用矢量网络分析(VNA)仪对D-PANI/Fe3O4空心球和PANI/Fe3O4空心球吸波性能进行分析,结果表明,D-PANI/Fe3O4空心球在12.64 GHz处的最小反射率为-43.3 d B,对应的匹配厚度为2 mm,其吸波性能明显优于PANI/Fe3O4空心球.     

Easy synthesis of hollow core, bimodal mesoporous shell carbon nanospheres and their application in supercapacitor

Hollow core, mesoporous shell carbon nanospheres (HCMSs) with large bimodal mesopores (6.4 and 3.1 nm) and high surface area (1704 m(2) g(-1)) have been synthesized by a triconstituent surface co-assembly of monodisperse silica nanospheres method. The resulted HCMS show a high specific capacity of 251 F g(-1) at 50 mV s(-1) in 2 M H(2)SO(4) and long cyclic life.     

大学化学综合实验:Fe/Fe3O4磁性材料的合成、结构性质与磁性能的测定*

推荐一个大学化学综合实验: Fe/Fe3O4磁性材料的合成、结构性质与磁性能的测定,该实验涉及材料的合成、结构表征和磁性能的测定。通过该实验可以使学生掌握一些大型仪器的基本原理和基本操作,掌握材料合成的方法、材料结构及形貌的表征手段以及磁滞曲线的测定方法。使学生在掌握材料研究的基础理论和基本实验技能的同时,培养学生独力实验能力和创新意识,尤其是培养他们综合运用知识的能力。进一步缩短教学与科研的距离。     

Fe3O4纳米催化剂的制备及其F-T合成性能研究

基于溶剂热合成体系,制备了不同形貌的Fe₃O₄微球和纳米片催化剂,考察了水热合成条件对Fe₃O₄晶粒形貌的影响,并研究了Fe₃O₄纳米催化剂的费托合成(F-T)性能。结果表明,成核和晶体生长速率是控制Fe₃O₄晶体形貌的关键。与传统的沉淀铁催化剂相比,Fe₃O₄纳米催化剂更容易还原和向活性相转变,因此,具有更高的F-T反应活性、低碳烯烃选择性及C₅₊选择性;Fe₃O₄微球催化剂比纳米片催化剂更易维晶粒的稳定,具有更高的反应活性和稳定性。     

Synthesis and application of magnetically recyclable nanocatalyst Fe3O4@Nico@Cu in the reduction of azo dyes

A novel method for synthesizing magnetically recyclable nanocatalyst Fe3O4@Nico@Cu (Nico =nicotinic acid) was introduced. The structural, morphological, and magnetic properties of the nano-catalyst were characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction, scanning electron microscopy, and vibrating sample magnetometry. Finally, Fe3O4@Nico@Cu was examined toward the hydrogenation of azo dyes methyl orange, methylene blue, eosin Y, and rho-damine B. The nanocatalyst showed excellent reusability properties that remained unchanged after several catalytic cycles. Therefore, the current findings show the potential of the prepared Fe3O4@Nico@Cu nanocatalyst as a candidate for application in the purification of organic aqueous pollutants for wastewater treatment.     

Fabrication and characterization of double‐shelled CeO2‐La2O3/Au/Fe3O4 hollow architecture as a recyclable and highly thermal stability nanocatalyst

A novel magnetic binary‐metal‐oxide‐coated nanocataly composing of a hollow Fe₃O₄ core and CeO₂‐La₂O₃ shells with Au nanoparticles encapsulated has been created in this work. The structural features of catalysts were characterized by several techniques, including SEM, TEM, UV‐vis, FTIR, XRD, XPS and TGA analyses. After the coating of CeO₂‐La₂O₃ layer, CeO₂‐La₂O₃/Au/C/Fe₃O₄ microspheres showed a superior thermal stability and catalytic reactivity compared with a pure CeO₂ or La₂O₃ layer. Accompanied by the burning of carbon layer, the specific surface could be increased by the formation of double‐shelled structure. Besides, the desired samples could be separated by magnet, implying the superior recycle performance. Using the reduction of 4‐nitrophenol by NaBH₄ as a model reaction, the microspheres exhibited highly reusability, superior catalytic activity, thermal stability, which are attributed to the unique double‐shelled structure of the support, uniform distribution of Au nanoparticles, the highly thermal stability of CeO₂‐La₂O₃ layer and mixed oxide synergistic effect. As a consequence, the unique nanocatalyst will open a promising way in the fabrication of the double‐shelled hollow binary‐metal‐oxide materials for future research and has great potential in other applications.