Synthesis of size-controlled cobalt ferrite particles with high coercivity and squareness ratio

Cobalt ferrite particles with diameters ranging from a few micrometer to about 15 nm were synthesized using a modified oxidation process. The fine control of the particle size was achieved by introducing various concentrations of Fe(3+) ions at the beginning of the reaction. Among the particle sizes obtained by using this method, particles with a grain size of about 36 nm showed a magnetization (M(s)) of 64 emu/g and a maximum coercivity (H(c)) of 2020 Oe at room temperature. The corresponding squareness ratio was found to be 0.53.     

Microvials with tungsten nanowire arrays

Nanostructured eutectic NiAl–W, fabricated using a Bridgman-type directional solidification facility, combines the advantages of single individual nanowires with the benefit of a conductive macroscopic matrix. Through an electrochemical dissolution step, using conditions derived from the combined Pourbaix diagrams of all three elements involved, the NiAl matrix is selectively dissolved allowing the release of embedded W nanowires. An application of micro-scale electrochemical techniques, such as scanning droplet cell microscopy, facilitates not only selective but moreover local matrix dissolution. Such a local dissolution leads to the formation of cavities on the micro-scale containing arrays of single crystalline W nanowires. In this connection, the depth and volume of fabricated microvials can directly be determined from the charge consumed during potentiostatic dissolution. A subsequent surface functionalisation enhances the hydrophobic behaviour, which is already observed for non-functionalised nanowire arrays, resulting in measured contact angles close to the border to superhydrophobicity.     

CdS nanoparticles sensitized large-scale patterned ZnO nanowire arrays for enhanced solar water splitting

Journal of Solid State Electrochemistry - CdS nanoparticle-sensitized patterned ZnO nanowire arrays (NWAs) were designed and synthesized through two-beam laser interference lithography (2BLIL),...     

Synthesis of hybrid nanowire arrays and their application as high power supercapacitor electrodes

Arrays of multi-segmented hybrid nanostructures of carbon nanotube and gold nanowires have been synthesized using a combination of chemical vapour deposition and electrodeposition methods and we further demonstrate that ultra-high power electrochemical double layer capacitors can be engineered using these hybrid nanowires, resulting in very high power densities.     

Efficient charge transfer and separation of TiO2@NiCo-LDH core-shell nanowire arrays for enhanced photoelectrochemical water-splitting

Journal of Solid State Electrochemistry - Efficient charge transfer and separation play a significant role in determining the photoelectrochemical (PEC) water-splitting performance of...     

Type-II CdS nanoparticle-ZnO nanowire heterostructure arrays fabricated by a solution process: enhanced photocatalytic activity

We report a two-step, solution-based synthetic method to fabricate CdS nanoparticles-sensitized ZnO nanowire heterostructure arrays which showed enhanced photocatalytic activities in comparison with bare ZnO nanowire arrays.     

Thermal properties of bi nanowire arrays with different orientations and diameters

The thermal properties of single-crystalline Bi nanowire arrays with different orientations and diameters were studied by differential scanning calorimeter and in situ high-temperature X-ray diffraction. Bi nanowires were fabricated by a pulsed electrodeposition technique within the porous anodic alumina membrane. The relationships between the orientation and diameter of Bi nanowires and the corresponding thermal properties are deduced solely from experimental results. It is shown that the melting point decreases with decreasing nanowire diameter, and there is an anisotropic thermal expansion property of Bi nanowires with different orientations and diameters. The transition of the thermal expansion coefficient from positive at low temperature to negative at high temperature for Bi nanowire arrays was analyzed and discussed.     

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.     

Fabrication of gold microtubes and microwires in high aspect ratio capillary arrays

In this communication, we describe the sequential deposition of materials in capillaries as a means to produce self-assembled three-dimensional gold microtubes, hollow gold microwires, and microtube and microwire arrays with unprecedented aspect ratios. The initial application of this technique is the fabrication of an array of microwires within a silica capillary array. The physical characteristics of these microwires are characterized via SEM, electrochemistry, and electrogenerated chemiluminescence emission.     

Tetracene-doped anthracene nanowire arrays: preparation and doping effects

Large-scale tetracene-doped anthracene nanowire arrays were prepared, and the doping effects were studied. The high doping concentration up to 10% (molar ratio) has been achieved, attributed to both the unique long-nanowire geometry and the excellent structural compatibility of anthracene and tetracene. The incorporation of long tetracene molecules into the matrix of short anthracene molecules induced an enlarged interlayer thickness, a decreased nanowire thickness, and an expanded nanowire width. The tetracene molecules were homogeneously embedded into the anthracene matrix at low doping concentrations (<1%). The doping became inhomogeneous at high doping concentrations (≥1%). The energy transfer efficiency between anthracene and tetracene is nearly 100% at doping concentrations ≥1%.     

High-performance, all-solution-processed organic nanowire transistor arrays with inkjet-printing patterned electrodes

Organic nanowire (NW) transistor arrays with a mobility of as high as 1.26 cm(2)·V(-1)·S(-1) are fabricated by combining the dip-coating process to align the NW into arrays with the inkjet printing process to pattern the source/drain electrodes. A narrow gap of ~20 μm has been obtained by modifying the inkjet process. The all-solution process is proven to be a low-cost, high-yield, simple approach to fabricating high-performance organic NW transistor arrays over a large area.     

Large-scale Ni-doped ZnO nanowire arrays and electrical and optical properties

Large-scale Ni-doped ZnO nanowire (NW) arrays are grown. The electrical conductivity of a single Ni-doped ZnO NW has been increased for 30 times. The photoluminescence (PL) spectrum of the doped ZnO NWs has a red shift, suggesting possible doping induced band edge bending. The doped NW arrays could be the basis for building integrated nanoscale transistors, sensors, and photodetectors.     

Ordered nickel oxide nanowire arrays and their optical absorption properties

Ordered NiO nanowire arrays embedded in anodic alumina membranes have been prepared by using an electrochemical deposition method. After annealing at 300 °C, the NiO nanowire arrays were characterized using SEM, TEM, SAED, and XRD. SEM and TEM observations reveal that these nanowires are dense, continuous and arranged roughly parallel to one another. XRD and SAED analysis together indicate that these NiO nanowires crystallize with a polycrystalline structure. The optical absorption band gap of NiO nanowire arrays is 3.74 eV, and no obvious blue shift or red shift with respect of that of the bulk NiO can be observed.     

Synthesis and characterization of axial heterojunction inorganic-organic semiconductor nanowire arrays

The end-to-end P-N heterojunction nanowire arrays combined organic (poly[1,4-bis(pyrrol-2-yl)benzene], BPB) and inorganic (CdS) molecules have been successfully designed and fabricated. The electrical properties of P-N heterojunctions of organic-inorganic nanowire arrays were investigated. The diode nature and rectifying feature of P-N heterojunction nanowire arrays were observed. The rectification ratio of the diode increased from 29.9 to 129.7 as the illumination intensity increased. The material exhibits a new property, which is an improvement in the integration of the physical and chemical properties of the two independent components.     

Template-based synthesis of nanorod, nanowire, and nanotube arrays

This review introduces and summarizes the fundamentals and various technical approaches developed for the template-based synthesis of nanorod, nanowire and nanotube arrays. After a brief introduction to various concepts for the growth of nanorods, nanowires and nanobelts, attention will be focused mainly on the most widely used and well established techniques for the template-based growth of nanorod arrays: electrochemical deposition, electrophoretic deposition, filling of templates by capillary force and centrifugation, and chemical conversion. In each section, relevant fundamentals will be first introduced, followed with examples to illustrate the specific details of each technique.     

Orthogonal PbS nanowire arrays and networks and their Raman scattering behavior

Three-dimensional, orthogonal lead sulfide (PbS) nanowire arrays and networks have been prepared by using a simple, atmospheric pressure chemical vapor deposition (APCVD) method. These uniform nanowires (average diameter 30 nm) grow epitaxially from the surface of the initial PbS crystal seeds and form orthogonal arrays and networks in space. The growth mechanism has been explored, and the process was classified as homogeneous, epitaxial growth in the 200 directions. Furthermore, Raman spectra of PbS nanowires are reported here, and their characteristic Raman peak (190 cm(-1), no shoulder) could be used as a unique probe for the study of PbS nanomaterials.     

ZnO nanowire arrays coating on TiO2 nanoparticles as a composite photoanode for a high efficiency DSSC

A novel composite photoanode with ZnO nanowire arrays coating on the top of TiO(2) nanoparticles is fabricated, and an efficiency of 4.52% is achieved for the composite cell, far higher than both 0.90% of the ZnO nanowire cell and 3.56% of the TiO(2) nanoparticle cell. The improved efficiency is resulted from the high surface area of nanoparticles, as well as fast electron transport and light scattering effect of nanowires.     

A novel non-enzymatic glucose sensor modified with Fe2O3 nanowire arrays

Fe(2)O(3) was generally considered to be biologically and electrochemically inert, and its electrocatalytic functionality has been rarely realized directly in the past. In this work, Fe(2)O(3) nanowire arrays were synthesized and electrochemically characterized. The as prepared Fe(2)O(3) nanomaterial was proved to be an ideal electrode material due to the intrinsic peroxidase-like catalytic activity. The Fe(2)O(3) nanowire array modified glucose sensor exhibited excellent biocatalytic performance towards the oxidation of glucose with a response time of <6 s, a linear range between 0.015-8 mM, and sensitivity of 726.9 μA mM(-1)cm(-1). Additionally, a high sensing selectivity towards glucose oxidation in the presence of ascorbic acid (AA) and dopamine (DA) has also been obtained at their maximum physiological concentrations, which makes the Fe(2)O(3) nanomaterial promising for the development of effective electrochemical sensors for practical applications.     

Au nanowires with high aspect ratio and atomic shell of Pt-Ru alloy for enhanced methanol oxidation reaction

The methanol oxidation reaction(MOR) is the limiting half-reaction in direct methanol fuel cell(DMFC).Although Pt is the most active single-metal electrocatalyst for MOR,it is hampered by high cost and CO poisoning.Constructing a Pt or Ru monolayer on a second metal substrate by means of galvanic replacement of underpotentially deposited(UPD) Cu monolayer has been shown as an efficient catalyst design strategy for the electrocatalysis of MOR because of the presumed 100% utilization of atoms and resistance to CO poisoning.Herein,we prepared one-dimensional surface-alloyed electrocatalyst from predominantly(111) faceted Au nanowires with high aspect ratio as the substrate of under-potential deposition.The electrocatalyst comprises a core of the Au nanowire and a shell of catalytically active Pt coated by Ru.Coverage-dependent electro-catalytic activity and stability is demonstrated on the Pt/Ru submonolayers on Au wires for MOR.Among all these catalysts,Au@Pt_(ML)@Ru_(ML) exhibits the best electrocatalytic activity and poisoning tolerance to CO.This presents a viable method for the rational catalyst design for achieving high noble-metal utilization efficiency and high catalytic performance.     

Aligned silicon carbide nanowire crossed nets with high superhydrophobicity

Aligned silicon carbide nanowire crossed nets (a-SiCNWNs) were directly synthesized by using a vapor-solid reaction at 1100 degrees C. Zinc sulfide was used as catalyst to assist the growth of a-SiCNWNs with small size and crystal structure. After functionalization with perfluoroalkysilane, a-SiCNWNs showed excellent superhydrophobic property with a high water contact angle more than 156 +/- 2 degrees , compared to random nanowires (147 +/- 2 degrees ) and pure silicon wafers (101 +/- 2 degrees ). The topographic roughness and chemical modification with CF 2/CF 3 groups contributed the better superhydrophobicity. Furthermore, the as-grown SiCNWNs can be scraped off and coated on other substrates such as pure silicon wafers. The novel nanowire coating with good superhydrophobicity displays extensive applications in silicon-related fields such as solar cells, radar, etc.