同轴静电纺丝技术制备Y2O3:Eu3＋@SiO2豆角状纳米电缆与表征

采用同轴静电纺丝技术, 以氧化钇、氧化铕、正硅酸乙酯(C₈H₂₀O₄Si)、无水乙醇、PVP和DMF为原料, 成功制备出大量的Y₂O₃:Eu^3＋@SiO₂豆角状纳米电缆. 用TG-DTA, XRD, SEM, TEM和荧光光谱等分析技术对样品进行了系统地表征． 结果表明, 得到的产物为Y₂O₃:Eu^3＋@SiO₂豆角状纳米电缆, 以无定型SiO₂为壳层, 晶态Y₂O₃:Eu^3＋球为芯, 电缆直径约为200 nm, 内部球平均直径约150 nm, 壳层厚度约为25 nm, 电缆长度＞300 μm. 纳米电缆内部为球状结构, 沿着纤维长度方向有序排列, 形貌均一. Y₂O₃:Eu^3＋@SiO₂豆角状纳米电缆在246 nm紫外光激发下, 发射出Eu^3＋离子特征的波长为614 nm的明亮红光. 对其形成机理进行了初步讨论.     

MWCNT@SiO_2纳米同轴电缆的制备及储锂性能

以多壁碳纳米管(MWCNT)为模板,通过正硅酸乙酯(TEOS)的水解缩聚反应制得MWCNT@SiO2纳米同轴电缆.采用透射电子显微镜(TEM)、扫描电子显微镜(SEM)和电化学测试对样品的形貌、结构及电化学性能进行表征.结果表明,MWCNT表面包覆了一层厚度均匀的多孔SiO2层,利于其获得较好的储锂性能.作为锂离子电池负极材料,MWCNT@SiO2纳米同轴电缆表现出了较高的比容量和较好的循环性能.在100 m A/g电流密度下经过80次循环,MWCNT@SiO2纳米同轴电缆的放电比容量仍高达431.7 m A·h/g,高于石墨材料的理论比容量(372 m A·h/g).     

Surface plasmon polariton and mode transformation in a nanoscale lossy metallic cylindrical cable

A theoretical investigation on the surface plasmon polariton in a gold cylindrical nanocable is presented. By solving a complete set of Maxwell＇s equations in the nanocable （with a 50 nm radius gold nanocore, 10-300 nm silica layer, and 30-200nm gold nanocladding）, the dispersion relations on the optical frequency and on the silica thickness are discussed. When the silica thickness varies from 50 to 250 nm, at a fixed waveleltgth, the strong coupling between the gold nanocore and the nanocladding leads to a symmetric-like surface mode and an antisymmetric-like surface mode in the nanocable. The transformation between the surface mode and the waveguide mode in this structure is also investigated. The results will be helpful for understanding the surface waves in the subwavelength structures.     

Fabrication of Zn/ZnO nanocables through thermal oxidation of Zn nanowires grown by RF magnetron sputtering

Fabrication of Zn/ZnO nanocables by thermal oxidation of Zn nanowires grown by RF magnetron sputtering is reported. Single crystalline Zn nanowires could be grown by controlling supersaturation of source material through the adjustment of temperature and Zn RF power. X-ray diffraction and high-resolution transmission electron microscopy showed that surfaces of these Zn nanowires, grown along the [0 1 0] direction, gradually oxidized inward the Zn core to form coaxial Zn/ZnO nanocables in the subsequent oxidation at 200 °C. In the Zn/ZnO nanocable, epitaxial relations of [1 0 0]_Zn//[1 0 0]_ZnO, and (0 0 1)_Zn//(0 0 1)_ZnO existed at the interface between the Zn core and ZnO shell. A number of dislocations were also observed in the interface region of the Zn/ZnO nanocable, which are attributed to large differences in the lattice constants of Zn and ZnO. With further increasing the oxidation temperature over 400 °C, Zn nanowires were completely oxidized to form polycrystalline ZnO nanowires. The results in this study suggest that coaxial Zn/ZnO nanocable can be fabricated through controlled thermal oxidation of Zn nanowires, yielding various cross-sectional areal fractions of Zn core and ZnO shell.     

同轴静电纺丝技术制备Y_2O_3:Eu~(3+)@SiO_2豆角状纳米电缆与表征

采用同轴静电纺丝技术,以氧化钇、氧化铕、正硅酸乙酯(C8H20O4Si)、无水乙醇、PVP和DMF为原料,成功制备出大量的Y2O3:Eu3+@SiO2豆角状纳米电缆.用TG-DTA,XRD,SEM,TEM和荧光光谱等分析技术对样品进行了系统地表征.结果表明,得到的产物为Y2O3:Eu3+@SiO2豆角状纳米电缆,以无定型SiO2为壳层,晶态Y2O3:Eu3+球为芯,电缆直径约为200nm,内部球平均直径约150nm,壳层厚度约为25nm,电缆长度300μm.纳米电缆内部为球状结构,沿着纤维长度方向有序排列,形貌均一.Y2O3:Eu3+@SiO2豆角状纳米电缆在246nm紫外光激发下,发射出Eu3+离子特征的波长为614nm的明亮红光.对其形成机理进行了初步讨论.     

Controllable synthesis,characterization and optical properties of Ag@AgCl coaxial core‐shell nanocables

Core‐shell structures often exhibit improved physical and chemical properties. Developing a relatively general, facile, and low temperature synthetic approach for core‐shell structures with complex compositions is still a particularly challenging work. Here we report a general chemical conversion route to prepare high quality Ag@AgCl coaxial core‐shell nanocables via the redox reaction between Ag nanowires and FeCl₃ in solution. The powder X‐ray diffraction of the Ag@AgCl coaxial core‐shell nanocables shows additional diffraction peaks corresponding to AgCl crystals apart from the signals from the Ag nanowire cores. Scanning electron microscopy and transmission electron microscopy images of the Ag@AgCl coaxial core‐shell nanocables reveal that the Ag nanowires are coated with AgCl nanoparticles. The effect of the molar ratio of Fe:Ag on the morphology and optical absorption of the Ag@AgCl coaxial core‐shell nanocables is systematically investigated. The result shows that the optical absorption of Ag nanowires decreases gradually and that of AgCl nanoparticles improves gradually with the increase of the molar ratio of Fe:Ag. The formation process of the Ag@AgCl coaxial core‐shell nanocables has been discussed in detail. The present chemical conversion approach is expected to be employed in a broad range of applications to fabricate innovative core‐shell structures with different compositions and shapes for unique properties. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Template Synthesis and Characterization of Cu2O/TiO2 Coaxial Nanocable for Photocatalysis

Coaxial nanocable consisted of p-type Cu₂O nanowires and n-type TiO₂ nanotubes arrays was prepared in the porous anodic aluminum oxide(AAO) template via the sol-gel method and subsequent electrodeposition method. X-ray diffraction analysis identified an anatase structure of the TiO₂ nanotubes and cubic structure of the Cu₂O nanowires. The obtained samples were also characterized by scanning electron microscopy(SEM), transmission electron microscopy(TEM) and energy dispersive X-ray spectroscopy(EDS). The diffrence of open circuit potential of the coaxial nanocable electrode was larger than that of the TiO₂ nanotubes electrode under ultraviolet illumination, which means doping with Cu₂O could improve the photovoltage effectively. Meanwhile, nanocable arrays exhibited a high activity for photodegrading Rhodamine B under Xe lamp irradiation and the photocatalysis degradation efficiency was up to 98.69% after degradation for 7 h. The enhanced photocatalytic activity could be attributed to the high migration efficiency of photoinduced electrons, which may suppress the charge recombination effectively.     

用离子吸附法制备银/聚吡咯同轴纳米电缆

以多元醇还原反应法制备出直径为40~50 nm的纳米银线, 采用醋酸铜水溶液对银纳米线表面进行处理, 通过离子吸附在纳米银线表面吸附铜离子. 以吸附在银纳米线表面上的铜离子作为活性单元, 氧化吡咯单体聚合, 制得Ag/PPy同轴纳米电缆. 采用TEM, FTIR和XPS等表征手段对产物进行表征和检测, 并通过表面增强拉曼光谱进一步证实产物中聚吡咯层紧密地吸附在银线表面. 结果表明, 利用醋酸铜作为氧化剂, 通过离子吸附法制备的Ag/PPy同轴纳米电缆, 可以在较大范围内有效地控制聚吡咯层厚度, 避免银纳米线被刻蚀.     

同轴三层纳米电缆NiO@SiO2@TiO2的制备与表征

采用静电纺丝技术, 通过改进实验装置, 成功地制备出了NiO@SiO₂@TiO₂同轴三层纳米电缆. 采用差热-热重(TG-DTA)分析、X射线衍射(XRD)分析、傅立叶变换红外光谱(FTIR)分析、扫描电子显微镜(SEM)分析和透射电子显微镜(TEM)等分析技术对样品进行表征, 结果表明, 所得产物为NiO@SiO₂@TiO₂同轴三层纳米电缆, 内层为NiO, 直径大约为40～50 nm|中间层为SiO₂, 厚度大约为40～45 nm|外层为TiO₂, 厚度大约为45～50 nm. 对NiO@SiO₂@TiO₂同轴三层纳米电缆的形成机理进行了讨论.     

n-ZnO/p-CuO同轴纳米线异质结的制备及其I-V特性

采用热蒸发气相沉积法在Si(100)衬底上生长直径约为60～70 nm的氧化锌(ZnO)纳米线,迸一步运用离子束溅射技术和热氧化工艺在ZnO纳米线表面形成含有均匀密集分布的超细氧化铜(CuO)纳米颗粒的CuO壳层,构成n-ZnO(核芯)/p-CuO(壳层)同轴纳米线异质结.扫描电子显微镜(SEM)、X射线衍射(XRD)、透射电子显微镜(TEM)和高分辨透射电子显微镜(HRTEM)用于研究样品的形貌、成分和晶体结构.实验结果表明,生长的ZnO纳米线呈纤锌矿单晶结构,CuO壳层为多晶结构.I-V曲线表明该同轴纳米线异质结构具有优良的二极管整流特性.这种具有大的异质结面积和高的比表面受光面积及强的表面化学活性的n-ZnO/p-CuO同轴纳米线异质结构在大电流密度的纳米整流器件、太阳能电池、光敏器件和气敏传感器等领域有很好的应用前景.