Synthesis of dendrimer-stabilized gold-polypyrrole core-shell nanoparticles

Core-shell composite nanoparticles consisting of a gold core and polypyrrole shell were prepared and stabilized with the poly(amidoamine) dendrimer. An in situ redox polymerization technique was used in which pyrrole reduced Au3+ to Au and then oxidized to polypyrrole. The presence of gold nanoparticles as a core was characterized by its surface plasmon absorption peak at 534 nm. Fourier transform infrared spectroscopy confirmed the presence of polypyrrole on the nanoparticle surfaces. The average diameter of the core-shell nanoparticle is 8.7 +/- 1.8 nm with a shell thickness of approximately 1.5-2.0 nm as estimated from the transmission electron microscopy image. Dissolution of the Au core using KCN enabled the formation of hollow polymer nanospheres.     

Preparation and characterization of PtRu nanoparticles supported on nitrogen-doped porous carbon for electrooxidation of methanol

N-doped porous carbon nanospheres (PCNs) were prepared by chemical activation of nonporous carbon nanospheres (CNs), which were obtained via carbonization of polypyrrole nanospheres (PNs). The catalysts, PtRu and Pt nanoparticles supported on PCNs and Vulcan XC-72 carbon black, were prepared by ethylene glycol chemical reduction. Transmission electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy were employed to characterize samples. It was found that PCNs containing N function groups possess a large number of micropores. Uniform and well-dispersed Pt and PtRu particles with narrow particle size distribution were observed. The electrooxidation of liquid methanol on these catalysts was investigated at room temperature by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy (EIS). The results showed that alloy catalyst (Pt(1)Ru(1)/PCN) possessed the highest catalytic activity and better CO tolerance than the other PtRu and Pt-only catalysts; PtRu nanoparticles supported on PCN showed a higher catalytic activity and more stable sustained current than on carbon black XC-72. Compared to commercial Alfa Aesar PtRu catalyst, Pt(1)Ru(1)/PCN reveals an enhanced and durable catalytic activity in methanol oxidation because of the high dispersion of small PtRu nanoparticles and the presence of N species of support PCNs.     

Synthesis of core-shell Au@polypyrrole nanocomposite using a dendrimer-template approach

Conducting polymeric nanostructures have been reported recently, which were produced from polypyrrole (PPy), including hollow nanocapsules, nanofibers, nanoporous membranes, nanowires, and nanofilms. In most cases, new synthetic routes were used aimed at controlling specific properties of these conducting nanostructures at the molecular level. In this communication we present a new chemical route to synthesize polypyrrole-based nanocomposites, in which polyamidoamine (PAMAM) dendrimers encapsulating Au nanoparticles are used as template. The two-step synthesis comprises the reduction of Au nanoparticles inside PAMAM molecules followed by PPy polymerization around the PAMAM-Au nanoparticles. The structure of the core-shell PAMAM-gold@polypyrrole nanospheres comprises a 40 nm PPy shell enclosing a core of 3 nm gold nanoparticles, as revealed by Transmission Electronic Microscopy (TEM). This new, environmentally-friendly approach may be suitable to produce hybrid nanomaterials for applications in catalysis, batteries, sensors, and micro/nanoelectronic devices.     

MⅡFe2O4（M=Fe,Ni）纳米空心微球的合成和磁性能（英文）

以气泡为模板,通过简单的一步水热法合成了尖晶石型MⅡFe2O4(M=Fe,Ni)纳米空心微球,并采用柠檬酸对其表面进行了修饰。利用X射线衍射(XRD)、扫描电子显微镜(SEM)、红外光谱(IR)和振动样品磁强计(VSM)对修饰前后纳米空心微球的形貌、结构和磁性能进行了表征。结果表明,MⅡFe2O4(M=Fe,Ni)纳米空心微球的尺寸在300～600nm,前躯体溶液的pH值大于9或反应时间小于12h都不能生成空心结构。此外,MⅡFe2O4(M=Fe,Ni)纳米空心微球呈现较好的超顺磁性,但与纳米Fe3O4实心微粒相比较,Fe3O4纳米空心微球的饱和磁化强度却有所降低。     

Monodisperse hematite porous nanospheres: synthesis, characterization, and applications for gas sensors

Monodisperse α-Fe(2)O(3) porous nanospheres with uniform shape and size have been synthesized via a facile template-free route. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and Raman spectroscopy were employed to characterize the product, showing the high quality of the as-prepared α-Fe(2)O(3) porous nanospheres. Furthermore, the α-Fe(2)O(3) porous nanospheres can selectively detect ethanol, formaldehyde and acetic acid, with a rapid response and high sensitivity, from a series of flammable and toxic/corrosive gases, indicating their potential applications for high sensitivity gas sensors.     

Fe3O4／壳聚糖纳米微球的制备与表征

采用原位聚合法制备分散性良好、粒径在300nm以下、兼具磁性能与荧光性能的Fe3O4／壳聚糖纳米微球,通过XRD、IR和SEM等对产物的组成、结构和微观形貌进行表征,利用荧光光谱分析Fe3O4壳聚糖纳米微球进行光学性能测试,实验结果表明,通过交联反应,Fe3O4被壳聚糖所包覆,产物显示出了非常好的荧光性能,并且在外加磁场下具有明显的磁响应行为。     

Facile synthesis and characterization of CdTe quantum dots–polystyrene fluorescent composite nanospheres

A novel method for the synthesis of CdTe quantum dots–polystyrene (CdTe/PS) composite nanospheres was developed by a two-step route. The as-prepared composite nanospheres were characterized by high-resolution transmission electron microscopy (HRTEM), X-ray powder diffraction (XRD), fluorescent microscope imaging and fluorescence spectrometer. The results showed that the composite nanospheres were spherical and relatively uniform with a diameter of 120 nm. Compared with previous methods, the proposed method was simple, efficient and inexpensive, moreover the composite nanospheres exhibited favorable water-dispersible, stable, size-tunable and fluorescent properties.     

Polyol synthesis and chemical conversion of Cu<Subscript>2</Subscript>O nanospheres

Polyol synthesis route, which is a popular and effective way of synthesizing noble metal nanocrystals, has been employed for the fabrication of Cu₂O nanospheres. With this method, the particle size of the product can be readily tailored by tuning the concentration of Cu(NO₃)₂ and/or poly(vinyl pyrrolidone). It has been demonstrated that the main driving force of this reaction is the difference in redox potentials between ethylene glycol (EG) and NO₃⁻, and not that between those of EG and Cu²⁺. The resulting Cu₂O nanospheres were used as a solid precursor for generating hollow nanospheres of copper sulfide with different sulfiding degrees, as well as CuO, via suitable chemical conversions. The Kirkendall effect determined the final hollow structure. The results in this paper provide a good example of the broadening of the scope of application of polyol synthesis route and may supply a thinking clue for the synthesis of other oxide materials.      

Preparation and characterization of ketorolac tromethamine-loaded ethyl cellulose micro-/nanospheres using different techniques

Sustained-release micro-/nanospheres of the ketorolac tromethamine (KTC) were prepared using four different techniques viz., single emulsion solvent evaporation, high pressure homogenization, spray drying, and using a microreactor. Ethyl cellulose (EC) was used as an encapsulating agent for the preparation of sustained-release micro-/nanospheres of KTC. The Plackett–Burman design was employed for design of the experiments. The resulting micro-/nanospheres were characterized for their size, morphology, encapsulation efficiency, and in vitro drug release performance. Interactions between the KTC and EC were quantified by Fourier transform infrared (FTIR) spectroscopy and X-ray powder diffractometry (XRPD). Particle morphology characterization was performed using field emission scanning electron microscopy. The micro-/nanospheres showed encapsulation efficiency of 42.34–89.33% by the solvent evaporation technique, 76.36–91.13% by the high-pressure homogenization technique, 70.74–79.68% by spray drying, and 79.00–89.49% by the microreactor technique. The micro-/nanospheres were found to be spherical and oval with smooth surface. The FTIR analysis confirmed no interaction of KTC with EC polymer. The XRPD analysis revealed good dispersion of the drug within the micro-/nanospheres formulation. Sustained KTC release profile over 12?h was achieved successfully by EC polymer. In conclusion, EC sustained-release micro-/nanospheres containing KTC can be prepared successfully using different techniques.     

Preparation and characterization of TiO2/polystyrene core-shell nanospheres via microwave-assisted emulsion polymerization

A combined procedure of sol-gel and microwave-assisted emulsion polymerization has been developed to prepare TiO₂/polystyrene core-shell nanospheres with nano-scale TiO₂ core and smooth and well-defined polystyrene shell. The core-shell structure and morphology were examined by TEM. The diameter and its distribution of the nanospheres were measured by dynamic light scattering. The nanospheres were characterized with Fourier transform infrared spectroscopy (FTIR). It is found that the diameter and its distribution of the TiO₂/polystyrene core-shell nanospheres can be regulated by the concentration of styrene monomer in the emulsion solution.     

聚吡咯涂层的制备及其对多孔316不锈钢抗腐蚀性能的影响

为提高粉末冶金烧结的多孔316不锈钢材料的耐腐蚀性能,采用恒电位沉积法在多孔316不锈钢表面制备了聚吡咯涂层。利用场发射扫描电镜(FE-SEM)、阳极极化曲线和电化学阻抗图谱(EIS)对试样的表面形貌和耐腐蚀性能进行了表征。结果表明负载了聚吡咯涂层的多孔316不锈钢材料表面呈球状,物相表征显示2θ=25.8°处有宽的吡咯环单元衍射峰。耐腐蚀性能测试表明负载聚吡咯的多孔不锈钢材料的电荷转移电阻大大增加,表明其耐腐蚀性能大大提升。120 h的浸泡试验表明负载聚吡咯的多孔不锈钢材料具有较强的耐蚀稳定性。     

Synthesis and characterization of Fe-Co binary ferrospinel nanospheres via one-step nonaqueous solution pathway

Fe-Co binary ferrospinel (CoFe₂O₄) nanospheres were synthesized by a facile nonaqueous solution route. X-ray diffraction (XRD) and electron diffraction (ED) showed that the obtained nanospheres had the cubic spinel structure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicated that the samples consisted of abundant uniform CoFe₂O₄ nanospheres with the particle size in the range of 35-40 nm. The magnetic properties of the sample were measured by using a vibrating sample magnetometer (VSM) at room temperature, which showed that the nanospheres exhibited a typical ferromagnetic behavior.     

Solvothermal synthesis of solid and hollow CoO nanospheres and their electrochemical properties in lithium-ion battery

Solid and hollow CoO nanospheres were synthesized by solvothermal method with oleic acid as reactant and SiO₂ as template. Each sample of high-purity CoO was characterized by X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy and X-ray photoelectron energy spectroscopy, respectively. Both solid and hollow CoO nanospheres as anode for lithium-ion battery were tested by galvanostatic discharge–charge experiments. The first discharge capacity of 1598 and 1640 mAh g^?1 was obtained at 0.1C for solid and hollow CoO nanospheres, respectively. Hollow CoO nanospheres showed better cycle performance.     

Comparison of the Solubility and Dissolution Rate Between Gliclazide Solid Complex and Its Nanospheres

ABSTRACT

The solid complex of gliclazide and β-cyclodextrin was prepared by neutralization method and the precipitation solvent evaporation method was used to prepare gliclazide nanospheres. Fourier-transform infrared spectroscopy and differential scanning calorimetry were used to examine whether gliclazide solid complex and gliclazide nanospheres were successfully formed in this study. The dissolution rate of gliclazide from its nanospheres was faster than its solid complex and pure drug. The morphology of particles for nanospheres showed no crystal character of gliclazide. In summary, the results indicate that nanotechnology provides better effects in solubility and dissolution rate of gliclazide than neutralization method.     

Surfactant-assisted fabrication of MoS2 nanospheres

The fabrication of MoS₂ nanospheres with an average diameter of 100 nm via a surfactant-assisted route was reported, in which an amorphous MoS₃ precursor was obtained by the aggregation transformation of surfactant at a low temperature and then transformed to the MoS₂ nanospheres with quasi-fullerene structures by thermal decomposition. The final products were characterized by XRD, IR, SEM, and TEM, respectively. The results indicate that the polyethylene glycol (PEG) promotes the formation of nanospheres and has a great effect on the microstructures, resulting in the abnormal expansion of lattice. The possible transformation mechanism of structures has been discussed based on the experimental results.     

Synthesis of V2O3/C composites with different morphologies by a facile route and phase transition properties of the compounds

V₂O₃ and amorphous carbon composites (V₂O₃/C composites) with different morphologies (e.g. nanospheres, nanorods and nanosheets) were, for the first time, successfully synthesized by a facile hydrothermal route and subsequent calcination. The as-obtained samples were characterized by X-ray powder diffraction (XRD), energy dispersive spectrometery (EDS), elemental analysis (EA), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The morphology of V₂O₃/C composites could be easily controlled by varying the reaction time, and, as a result, V₂O₃/C composites with nanospheres, nanorods and nanosheets were selectively synthesized. Furthermore, the phase transition property of V₂O₃/C composites was measured by differential scanning calorimetry (DSC), suggesting that V₂O₃/C composites exhibit the phase transition similar to V₂O₃, which could expand the potential applications of materials related to V₂O₃ in the future.     

Comparison of the solubility and dissolution rate between gliclazide solid complex and its nanospheres

The solid complex of gliclazide and β-cyclodextrin was prepared by neutralization method and the precipitation solvent evaporation method was used to prepare gliclazide nanospheres. Fourier-transform infrared spectroscopy and differential scanning calorimetry were used to examine whether gliclazide solid complex and gliclazide nanospheres were successfully formed in this study. The dissolution rate of gliclazide from its nanospheres was faster than its solid complex and pure drug. The morphology of particles for nanospheres showed no crystal character of gliclazide. In summary, the results indicate that nanotechnology provides better effects in solubility and dissolution rate of gliclazide than neutralization method.     

Preparation of conductive polypyrrole-palladium composite nanospheres by inverse microemulsion polymerization

Conductive polypyrrole-palladium (PPy-Pd) composite nanospheres of about 50 nm in diameter, containing dispersed Pd metal nanoparticles of about 2-4 nm in size, were prepared in a 1-step oxidative polymerization of pyrrole by Pd(NO3)2. Pyrrole was oxidized by Pd(NO3)2 in an inverse microemulsion polymerization system, yielding PPy nanospheres and elemental Pd nanoparticles simultaneously. Palladium nanoparticles were uniformly dispersed in the nanospheres of PPy chains. The latter also exhibited an enhanced effective conjugation. The chemical composition of the PPy-Pd composite nanospheres was characterized by X-ray photoelectron spectroscopy and FTIR spectroscopy. The crystalline structure of the Pd nanoparticles was deduced from X-ray diffraction patterns. The morphology of the composites was revealed by scanning and transmission electron microscopy.     

Facile hydrothermal synthesis and characterization of LaFeO3 nanospheres for visible light photocatalytic applications

LaFeO₃ nanospheres were synthesized by hydrothermal method followed by calcination. Citric acid was found to be key factor to the purity and the surface morphology of the LaFeO₃ nanospheres. The obtained nanospheres have been structurally characterized by XRD which confirms the single crystalline orthorhombic structure. The structural information of the nanosphere was also confirmed from the Raman spectrum. HRSEM and AFM revealed that the prepared sample has been composed of spherical like morphology with an average size of about 45 nm. From XPS analysis, the chemical state of the LaFeO₃ nanospheres was confirmed. Magnetic measurement indicates the products shows weak magnetic behaviour. The UV–Vis spectroscopy analysis shows strong absorption at 466 nm which confirms that the obtained material has excellent visible light absorption ability. Furthermore, the photocatalytic experiment demonstrates that the prepared LaFeO₃ nanospheres exhibit well and stable photocatalytic activity for decomposition of methyl orange under visible-light irradiation.     

Fabrication of multiwalled carbon nanotubes/polypyrrole/Prussian blue ternary composite nanofibers and their application for enzymeless hydrogen peroxide detection

In this article, Prussian blue (PB) covered multiwalled carbon nanotubes (MWCNTs)/polypyrrole (PPy) ternary composite nanofibers with good dispersibility in water and ethanol have been prepared by directly mixing ferric-(III) chloride and potassium ferricyanide in the presence of MWCNT/PPy coaxial nanofibers under ambient conditions. Transmission electron microscopy shows that the as-synthesized PB nanoparticles covered on the surface of MWCNT/PPy nanofibers. Fourier-transform infrared spectroscopy, UV–Visible spectroscopy, and X-ray diffraction patterns have been used to characterize the obtained MWCNT/PPy/PB ternary composite nanofibers. The MWCNT/PPy/PB ternary composite nanofibers exhibit good electrocatalytic response to detection of H₂O₂ and provide a new material to modify electrode for amperometric biosensors.