Large-area Sb2Te3 nanowire arrays

High-density large-area nanowire arrays of thermoelectric material Sb(2)Te(3) have been successfully prepared using electrochemical deposition into the channels of the porous anodic alumina membrane. The morphologies, structure, and composition of the as-prepared Sb(2)Te(3) nanowires have been characterized using field-emission scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. Individual Sb(2)Te(3) nanowires are single crystalline and continuous with uniform diameters ( approximately 50 nm) throughout the entire length. The atomic ratio of Sb to Te is very close to the 2:3 stoichiometry.     

Direct electrodeposition of Cu2Sb for lithium-ion battery anodes

We describe the direct single potential electrodeposition of crystalline Cu2Sb, a promising anode material for lithium-ion batteries, from aqueous solutions at room temperature. The use of citric acid as a complexing agent increases the solubility of antimony salts and shifts the reduction potentials of copper and antimony toward each other, enabling the direct deposition of the intermetallic compound at pH 6. Electrodeposition of Cu2Sb directly onto conducting substrates represents a facile synthetic method for the synthesis of high quality samples with excellent electrical contact to a substrate, which is critical for further battery testing.     

High density copper nanowire arrays deposition inside ordered titania pores by electrodeposition

Large area and free-standing TiO₂ films was prepared by ultrasonic splitting and a chemical etching step was used to open the closed bottom end of TiO₂ films and yields a high aspect-ratio anodic titanium oxide membrane open at both ends. Ordered Cu nanowire structures were fabricated by a simple electroplating method inside high aspect-ratio anodic titanium oxide membrane. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and the X-ray diffraction (XRD) were employed to characterize the resulting samples. Detailed results and the possible mechanism are presented.     

Synthesis and characterization of highly ordered BiFeO3 multiferroic nanowire arrays

We report the synthesis and characterization of multiferroic BiFeO₃ (BFO) nanowires. The perovskite BFO nanowires with diameters about 60 nm and lengths about 10 μm were fabricated by means of the sol-gel method utilizing nanochannel alumina templates with post annealing at 700 °C. The microstructure of the BFO nanowires was investigated by means of x-ray diffraction and transmission electron microscopy, and the ferroelectric characteristic of BFO nanowires were demonstrated.     

The electrodeposition of high-density,ordered arrays of Bi1-xSbx nanowires

Here we report the synthesis of dense arrays of Bi1-xSbx nanowires with >5 x 1010 nanowires/cm2. The individual wires are crystalline, relatively homogeneous, and highly textured in a 110 direction, with diameters of 40 nm and a composition of x = 12-15 atom % Sb. By tuning the solution concentrations and controlling the growth rate by controlling the potential, the composition, crystallinity, and morphology of the nanowires can be varied.     

Electrodeposited fabrication of highly ordered Pd nanowire arrays for alcohol electrooxidation

Highly ordered Pd nanowire arrays (NWAs) are prepared using a porous aluminum oxide template by pulse electrodeposition. The obtained Pd nanowire arrays with the diameter of 50 nm and length of 850 nm have been characterized by scanning electron microscopy, energy dispersive X-ray analysis, and high resolution transmission electron microscope. Meanwhile, the electrocatalytic activity of Pd NWAs electrodes for methanol and isopropanol oxidation in alkaline media is studied. It is found that the obtained nanostructures exhibit excellent catalytic activity for alcohol electrooxidation. The isopropanol oxidation shows the higher activity on Pd NWAs electrode than methanol in alkaline medium.     

Direct electrodeposition of Pt nanotube arrays and their enhanced electrocatalytic activities

Ordered Pt nanotube arrays have been fabricated by one-step electrodeposition utilizing nanochannel alumina templates. The electro-oxidation of ethanol on Pt nanotube arrays in acidic medium has been investigated by cyclic voltammetry. The oxidation peak currents on the Pt nanotube array electrode for ethanol oxidation are about 1.7 times those on the commercial PtRu/C electrode. The high electrocatalytic activities of the Pt nanotube array towards the oxidation of ethanol made it an excellent platform for direct ethanol fuel cell applications.     

Direct electrodeposition of FeCoZn wire arrays from a zinc chloride-based ionic liquid

The use of Zinc chloride-1-ethyl-3-methylimidazolium chloride ionic liquid enables facile template-free electrochemical fabrication of arrays of polycrystalline ternary FeCoZn nanowires with diameter of 100–200 nm by controlling the deposition potential. The nanowire arrays were characterized by scanning electron microscopy, powder X-ray diffraction and transmission electron microscopy.     

One-step nanocasting synthesis of highly ordered single crystalline indium oxide nanowire arrays from mesostructured frameworks

A one-step nanocasting route has been demonstrated to prepare highly ordered single-crystal indium oxide nanowire (IONW) arrays with mesostructured frameworks. Unlike the reported multistep nanocasting process (synthesis of mesoporous materials, and then incorporation of precursors and formation of inorganic frameworks), a highly ordered mesostructured surfactant-silica monolith with low external surface serves as both the template and the reducing agent and makes the formation of single-crystal IONWs in its channels easily in one step by using normal In(NO(3))(3) as an inorganic precursor. After silica is removed, highly ordered uniform single-crystal IONW arrays with hexagonal (p6mm) or cubic (Ia3d) mesostructures are derived. These new materials are studied by XRD, SEM, TEM, N(2) adsoption, and UV spectrum. Furthermore, this one-step nanocasting synthesis route is a generalized method and can be used to synthesized a highly ordered mesoporous silica monolith with metal oxide nanocrystals in its channels. To the best of our knowledge, this is the first report of a single crystalline mesostructured In(2)O(3) framework.     

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.     

Direct electrodeposition of aluminium nano-rods

Electrodeposition of aluminium within an alumina nano-structured template, for use as high surface area current collectors in Li-ion microbatteries, was investigated. The aluminium electrodeposition was carried out in the ionic liquid 1-ethyl-3-methylimidazolium chloride:aluminium chloride (1:2 ratio). First the aluminium electrodeposition process was confirmed by combined cyclic voltammetry and electrochemical quartz crystal microbalance measurements. Then, aluminium was electrodeposited under pulsed-potential conditions within ordered alumina membranes. A careful removal of the alumina template unveiled free standing arrays of aluminium nano-rods. The nano-columns shape and dimensions are directly related to the template dimensions. To our knowledge, this is the first time that direct electrodeposition of aluminium nano-pillars onto an aluminium substrate is reported.     

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     

Perpendicular growth of catalyst-free germanium nanowire arrays

High yields of single-crystalline Ge nanowires (NWs) were synthesised in the vapour phase of a high boiling point organic solvent without the need for metal catalyst particles. High density, perpendicular arrays of Ge NWs were subsequently grown from ITO coated substrates. The approach represents a convenient route toward orientated arrays of catalyst-free Ge NWs.     

Electrochemical aspects and structure characterization of VA-VIA compound semiconductor Bi2Te3/Sb2Te3 superlattice thin films via electrochemical atomic layer epitaxy

This paper concerns the electrochemical atom-by-atom growth of VA-VIA compound semiconductor thin film superlattice structures using electrochemical atomic layer epitaxy. The combination of the Bi2Te3 and Sb2Te3 programs and Bi2Te3/Sb2Te3 thin film superlattice with 18 periods, where each period involved 21 cycles of Bi2Te3 followed by 21 cycles of Sb2Te3, is reported here. According to the angular distance between the satellite and the Bragg peak, a period of 23 nm for the superlattice was indicated from the X-ray diffraction (XRD) spectrum. An overall composition of Bi 0.25Sb0.16Te0.58, suggesting the 2:3 stoichiometric ratio of total content of Bi and Sb to Te, as expected for the format of the Bi2Te3/Sb2Te3 compound, was further verified by energy dispersive X-ray quantitative analysis. Both field-emission scanning electron microscopy and XRD data indicated the deposit grows by a complex mechanism involving some 3D nucleation and growth in parallel with underpotential deposition. The optical band gap of the deposited superlattice film was determined as 0.15 eV by Fourier transform infrared spectroscopy and depicts an allowed direct type of transition. Raman spectrum observation with annealed and unannealed superlattice sample showed that the LIF mode has presented, suggesting a perfect AB/CB bonding in the superlattice interface.