Highly ordered MnO2 nanowire array thin films on Ti/Si substrate as an electrode for electrochemical capacitor

AAO/Ti/Si substrate was successfully synthesized by a two-step electrochemical anodization of the aluminum film on the Ti/Si substrate and then used as template to grow nanowire arrays. The ordered MnO₂ nanowire arrays with about 40 nm diameters had been directly fabricated on AAO/Ti/Si substrate by direct current (DC) electrodeposition. The microstructure of the nanowire arrays was investigated by field-emission scanning electron microscopy, transmission electron microscopy and X-ray diffraction. Their electrochemical characterization was performed using cyclic voltammetry in 0.5 M Na₂SO₄ aqueous solution. The synthesized MnO₂ nanowires had amorphous nature until 400 °C. The deal capacitive behavior was obtained when the as-prepared sample was heat-treated at 200 °C. The specific capacitance of the electrode was about 254 F/g.     

Ambient template synthesis of multiferroic MnWO4 nanowires and nanowire arrays

The current report describes the systematic synthesis of polycrystalline, multiferroic MnWO₄ nanowires and nanowire arrays with controllable chemical composition and morphology, using a modified template-directed methodology under ambient room-temperature conditions. We were able to synthesize nanowires measuring 55±10, 100±20, and 260±40 nm in diameter, respectively, with lengths ranging in the microns. Extensive characterization of as-prepared samples has been performed using X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, and energy-dispersive X-ray spectroscopy. Magnetic behavior in these systems was also probed.     

Synthesis of ordered Al nanowire arrays

Ordered Al nanowire arrays with the same nanowire density but the diameters decrease radially embedded in one piece of anodic alumina membranes were successfully fabricated by two-step synthesis: electrodeposition of Zn and replacement in AlCl₃ solution. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and selected-area electron diffraction techniques were used to characterize the Al nanowires obtained. SEM and TEM images taken from the different areas of Al nanowire arrays show that we can control the growth of aligned Al nanowires with different diameters in a single process at the same time. The investigation results not only have potential applications in photoelectric devices but also open up a new method for fabricating nano-scale materials.     

Template synthesis and characterization of PbTiO3 nanowire arrays from aqueous solution

Highly ordered PbTiO₃ nanowire arrays were first reported by fabricating within the pores of anodic aluminum oxide (AAO) template in the aqueous solution by liquid-phase deposition method. The structure and morphology of PbTiO₃ nanowire arrays were characterized by SEM and TEM, respectively. The XRD result shows that desired stoichiometric composition could be easily obtained preparing the treatment solution during post-annealing in order to crystallize the nanowires. TEM analyses confirmed that the obtained nanowires composed of large crystals than others made by sol-gel methods. Finally, a possible growth mechanism of the PbTiO₃ nanowires is discussed.     

不同取向的CoSb3纳米线阵列的电化学法制备

近年来,金属纳米线及其阵列由于其新奇的物理和化学特性和在纳米器件方面潜在的应用前景,越来越受到人们的关注。氧化铝模板合成一维纳米材料具有设备简单、制作方便等优点,因而成为近年来人们常用的一种方法。利用电化学沉积的方法在多孔氧化铝模板中沉积各种成分的纳米线已成为纳米材料制备的一种常见的方法。这种方法不仅可以得到大面积有序的纳米线阵列,还可以根据需要调节孔洞的大小来控制纳米线的直径[1￣3]。最近理论研究结果预言[4￣6],由于纳米材料的量子限域效应,热电材料的纳米线将有比其相应块体材料更高的品质因数n,这极大地激…     

One-step growth of Si3N4 stem-branch featured nanostructures: Morphology control by VS and VLS mode

We report here one-step synthesis of Si₃N₄ nanodendrites by selectively applying a vapor-solid (VS) and vapor-liquid-solid (VLS) strategy via direct current arc discharge method. The resultant nanodendrites were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy and X-ray powder diffraction. The spine-shaped nanodendrites were generated by a noncatalytic growth following a VS mode. The uniform secondary nanowire branches were epitaxial grown from two side surfaces of the nanowire stems. The pine-shaped nanodendrites were obtained through a catalytic growth in a VLS process. These branch nanowires were unsystematically grown from the nanocone-like stems. The photoluminescence spectra of the nanodendrites show a strong white light emission around 400-750 nm, suggesting their potential applications in light and electron emission devices.     

Tl2O3/聚-N-乙烯基咔唑复合纳米线的研究

Stable monolayers of electropolymerized poly-N-vinylcarbazole (EPVK) and arachidic acid(AA) are obtained on a subphase of alkaline Tl2O3 colloidal solutions. As revealed by the atomic force microscope, there is phase separation in the mixed LB monolayers. Transmission electron microscopic observations reveal that ordered arrays of composite Tl2O3/Epvk nanowires are formed in the mixed monolayers. Formation of the composite nanowire arrays is attributed to the ordered adsorption of Tl2O3 colloidal particles along the polycationic EPVK chains. The composite nanowire array is 3.2nm wide with a spacing of 2.7nm.The composite nanowire arrays can also be formed when pure EPVK is used. Composite LB multilayers of Tl2O3/EPVK nanowire arrays are prepared. The bilayer spacing is 5.54nm.The present study is of importance to the fabrication of inorganic semiconductor/functional polymer composite nanowires.     

Electrochemical synthesis of ordered alumina nanowire arrays

Ordered Al₂O₃ nanowire arrays embedded in the nanochannels of anodic alumina membranes (AAMs) were synthesized by electrodepostion at room temperature. Our synthetic route yielded large quantities of Al₂O₃ nanowires of uniform size and shape that are ~40 μm long with diameters of 70 nm. The Al₂O₃ nanowire structures were characterized by scanning and transmission electron microscopies, high-resolution transmission electron microscopy, energy dispersive spectroscopy and X-ray photoelectron spectroscopy. Electronic Publication     

Sol-Gel Template Synthesis of Highly Ordered LiCo0.5Mn0.5O2 Nanowire Arrays and Their Structural Properties

Highly ordered LiCo_0.5Mn_0.5O₂ nanowire arrays were prepared using porous anodic aluminum oxide (AAO) template from sol-gel solution containing Li(CH₃COO), Co(CH₃COO)₂, and Mn(CH₃COO)₂. Electron microscope results showed that uniform length and diameter of LiCo_0.5Mn_0.5O₂ nanowires were obtained, and the length and diameter of LiCo_0.5Mn_0.5O₂ nanowires are dependent on the pore diameter and the thickness of the applied AAO template. X-ray diffraction and electron diffraction pattern investigations demonstrate that LiCo_0.5Mn_0.5O₂ nanowires are a layered structure of LiCo_0.5Mn_0.5O₂ crystal. X-ray photoelectron spectroscopy analysis indicates that the most closely resembling stoichiometric layered LiCo_0.5Mn_0.5O₂ material has been obtained.     

Direct electrodeposition of highly dense Bi/Sb superlattice nanowire arrays

Ordered arrays of Bi/Sb superlattice nanowires with diameters of about 50 nm have been produced by pulsed electrodeposition technique into the pores of anodic alumina membrane (AAM). The structure of Bi/Sb superlattice nanowire can be modulated by controlling the electrodeposition conditions.     

Growth of Au/Ag nanowires in thin surfactant solution films: an electron microscopy study

The surfactant templated gold-silver nanowire growth process in a thin solution film was probed by cryo-transmission electron microscopy (cryo-TEM). The increasing surfactant concentration upon film drying appears to induce phase transformations in the film and form a liquid crystalline template for the nanowires growth. High-resolution transmission electron microscopy (HRTEM) and electron holography revealed that the nanowires were polycrystalline with some preferred crystallite orientations and had a roughly cylindrical cross-section. Further improvement of the technique may lead to highly ordered metal nanowire arrays within the surfactant matrix similar to the closely related mesoporous materials.     

有序CdS纳米线阵列的制备和光学特性

应用直流电沉积法在多孔氧化铝模板中制备了高度有序的CdS纳米线阵列,并由XRD、Raman、SEM、TEM和HRTEM等进行物理化学表征.结果表明,沉积在多孔氧化铝模板中的CdS呈六角结构,c轴沿孔长度方向定向生长.紫外吸收光谱研究表明,随着纳米线尺寸的减小,纳米线阵列的吸收边向短波长方向移动,荧光光谱测量显示,CdS纳米线阵列的荧光强度高于氧化铝模板,而且在可见光区的荧光特性与激发波长无关.     

Size-dependent orientation growth of large-area ordered Ni nanowire arrays

Large-area ordered Ni nanowire arrays with different diameters have been fabricated by the direct current electrodeposition into the holes of porous anodic alumina membrane. The crystal structure and micrograph of nanowire arrays are characterized by X-ray diffraction, field-emission scanning electron microscopy and high-resolution transmission electron microscopy. The results indicate that the growth orientation of Ni nanowires turns from [110] to [111] direction with increasing diameters of nanowires. The mechanism of the growth was discussed in terms of interface energy minimum principle. The size-dependent orientation of Ni nanowire arrays has the important significance for the design and control of nanostructures.     

Densely packed single-crystal Bi2Fe4O9 nanowires fabricated from a template-induced sol-gel route

Densely packed single-crystal Bi₂Fe₄O₉ nanowires were successfully synthesized by a template-induced citrate-based sol-gel process. The structural properties of the nanowires were characterized using many techniques. The results of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that Bi₂Fe₄O₉ nanowires possessed a uniform length and diameter, which were controlled by the thickness and the pore diameter of the applied porous anodic aluminum oxide (AAO) template, respectively. The results of X-ray diffraction (XRD) and the selected area electron diffraction (SAED) indicated that Bi₂Fe₄O₉ nanowires had an orthorhombic single-crystal structure. Furthermore, the energy-dispersive X-ray (EDX) spectroscopy demonstrated that the stoichiometric Bi₂Fe₄O₉ was formed. The possible formation mechanism of nanowires was also discussed.     

Electrodeposited highly-ordered manganese oxide nanowire arrays for supercapacitors

Large arrays of well-aligned Mn oxide nanowires were prepared by electrodeposition using anodic aluminum oxide templates. The sizes of nanowires were tuned by varying the electrotype solution involved and the MnO₂ nanowires with 10 μm in length were obtained in a neutral KMnO₄ bath for 1 h. MnO₂ nanowire arrays grown on conductor substance save the tedious electrode-making process, and electrochemical characterization demonstrates that the MnO₂ nanowire arrays electrode has good capacitive behavior. Due to the limited mass transportation in narrow spacing, the spacing effects between the neighbor nanowires have show great influence to the electrochemical performance.     

Fabrication and characterization of single-crystalline ZnTe nanowire arrays

Semiconductor ZnTe nanowire arrays have been synthesized by the pulsed electrochemical deposition from aqueous solutions into porous anodic alumina membranes. X-ray diffraction analyses show that the as-synthesized nanowires have a highly preferential orientation. Scanning electron microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy indicate that high-filling, ordered, and single-crystalline nanowire arrays have been obtained. The optical absorption spectra of the nanowire arrays show that the optical absorption band edge of the ZnTe nanowire array exhibits a blue shift compared with that of bulk ZnTe. The growth mechanism and the electrochemical deposition process are discussed together with the chemical compositions analysis.     

铅纳米线阵列的制备

使用电化学沉积方法,在有序的氧化铝模板(AAO)孔洞中制备了铅纳米线有序阵列。用X射线衍射仪(XRD)、场发射扫描电子显微镜(FE-SEM)、透射电子显微镜(TEM)对样品的结构、形貌、进行表征和观测。XRD的结果表明所制备的样品为纯的立方面心铅,且纳米线生长沿<220>有很好的取向。FE-SEM的图片清晰地说明铅纳米线阵列是大面积、高填充率和高度有序的。TEM的结果显示纳米线直径均匀、表面光滑且长径比大。     

大面积Bi单晶纳米线阵列的制备

在有序的氧化铝模板(AAO)的孔洞中, 采用电化学沉积工艺成功地制备了准金属Bi纳米线有序阵列. 使用X射线衍射仪(XRD)、场发射扫描电子显微镜(FE-SEM)、透射电子显微镜(TEM)及高分辨电子显微镜(HRTEM)对样品的结构和形貌进行了表征. XRD结果表明, 所制备的铋样品为六方相, 且沿[110]方向有很好的生长取向; FE-SEM图片清晰地说明铋纳米线阵列是大面积、填充率高和高度有序的; TEM的结果显示纳米线直径均匀、表面光滑且长径比大; HRTEM图片中清晰的晶格条纹和选区电子衍射(SAED)结果表明纳米线是单晶.     

Electrochemical characterization of vertical arrays of tin nanowires grown on silicon substrates as anode materials for lithium rechargeable microbatteries

Vertical arrays of one-dimensional tin nanowires on silicon dioxide (SiO₂)/silicon (Si) substrates have been developed as anode materials for lithium rechargeable microbatteries. The process is complementary metal-oxide-semiconductor (CMOS) compatible for fabricating on-chip microbatteries. Nanoporous anodized aluminum oxide (AAO) templates integrated on SiO₂/Si substrates were employed for fabrication of tin nanowires resulting in high surface area of anodes. The microstructure of these nanowire arrays was investigated by scanning electron microscopy and X-ray diffraction. The electrochemical tests showed that the discharge capacity of about 400 mA h g⁻¹ could be maintained after 15 cycles at the high discharge/charge rate of 4200 mA g⁻¹.     

ZnO纳米线阵列的电沉积法制备及表征(英文)

利用直流电沉积方法在多孔氧化铝模板的孔洞中生成锌纳米线,在氧气氛围中,于800°C下氧化2h,将氧化铝中的锌氧化成氧化锌.本研究利用氧气氛围进行锌的氧化,大大提高了传统方法的氧化锌纳米线的制备效率.用场发射扫描电子显微镜(FE-SEM)、透射电子显微镜(TEM)和X射线衍射仪(XRD)对其形貌及成分进行表征和分析,结果表明,氧化铝模板的有序孔洞中填充了大尺寸、均匀连续的多晶态氧化锌纳米线.纳米线具有约1000:1的高纵横比,其长度等于氧化铝模板的厚度,直径约为80nm.光致发光(PL)光谱表明,氧化锌纳米线在504nm处有由于氧空位引起的较强蓝绿光发射.这为进一步研究ZnO/AAO组装体发学性质和开发新型功能器件提供了基础.