Core Shell Nanocables Research Articles

Core-Shell Nanocables Decorated with Carbon Spherical Shells and Silver Nanoparticles for Sensing Ethinylestradiol Hormone in Water Sources and Pills.

The selective, rapid detection of low levels of hormones in drinking water and foodstuffs requires materials suitable for inexpensive sensing platforms. We report on core-shell Ag@C nanocables (NCs) decorated with carbon spherical shells (CSSs) and silver nanoparticles (AgNPs) by using a hydrothermal green approach. Sensors were fabricated with homogeneous, porous films on screen-printed electrodes, which comprised a 115 nm silver core covered by a 122 nm thick carbon layer and CSSs with 168 nm in diameter. NCs and CSSs were also decorated with 10-25 nm AgNPs. The NC/CSS/AgNP sensor was used to detect ethinylestradiol using square wave voltammetry in 0.1 M phosphate buffer (pH 7.0) over the 1.0-10.0 μM linear range with a detection limit of 0.76 μM. The sensor was then applied to detect ethinylestradiol in tap water samples and a contraceptive pill with recovery percentages between 93 and 101%. The high performance in terms of sensitivity and selectivity for hormones is attributed to the synergy between the carbon nanomaterials and AgNPs, which not only increased the sensor surface area and provided sites for electron exchange but also imparted an increased surface area.

The fabrication and thermal properties of bismuth–aluminum oxide nanothermometers

Bismuth (Bi) nanowires, well controlled in length and diameter, were prepared by using an anodic aluminum oxide (AAO) template-assisted molding injection process with a high cooling rate. A high performance atomic layer deposition (ALD)-capped bismuth–aluminum oxide (Bi–Al2O3) nanothermometer is demonstrated that was fabricated via a facile, low-cost and low-temperature method, including AAO templated-assisted molding injection and low-temperature ALD-capped processes. The thermal behaviors of Bi nanowires and Bi–Al2O3 nanocables were studied by in situ heating transmission electron microscopy. Linear thermal expansion of liquid Bi within native bismuth oxide nanotubes and ALD-capped Bi–Al2O3 nanocables were evaluated from 275 °C to 700 °C and 300 °C to 1000 °C, respectively. The results showed that the ALD-capped Bi–Al2O3 nanocable possesses the highest working temperature, 1000 °C, and the broadest operation window, 300 °C–1000 °C, of a thermal-expanding type nanothermometer. Our innovative approach provides another way of fabricating core–shell nanocables and to further achieve sensing local temperature under an extreme high vacuum environment.

Nanowire-templated formation of SnO2/carbon nanotubes with enhanced lithium storage properties.

In this work, we have designed and synthesized SnO2 nanotubes wrapped by a porous carbon layer via a multistep method. Single-crystalline MnO(x) nanowires are employed as the template. SnO2 is grown on MnO(x) nanowires by a simple hydrothermal method to generate MnO(x)/SnO2 core-shell nanocables, followed by further coating with a layer of polydopamine. After carbonization of polydopamine and selective removal of MnO(x) nanowires, carbon coated SnO2 nanotubes are obtained. This structure combines several advantages. First, the internal empty space of the tubular structure can buffer the huge volume variation during lithium insertion-extraction processes properly, leading to improved cycling performance. Second, the nanosized SnO2 subunits and porous carbon coating not only shorten the distance for lithium ion diffusion but also offer large electrode-electrolyte contact area for fast Li(+) crossing the interface, thus enabling improved rate capability. Third, the flexible carbon coating is closely covered onto the SnO2 nanocrystals, which could facilitate the electronic transport and also significantly mitigate the pulverization. As a result, the as-synthesized SnO2/C-NT nanocomposites exhibit a high reversible capacity of 596 mA h g(-1) after 200 cycles, as well as an outstanding rate capability.

Electrodeposition of three-dimensional ZnO@MnO2 core–shell nanocables as high-performance electrode material for supercapacitors

Hybrid nano-architecture for supercapacitors has been designed by growing three-dimensional ZnO@MnO2 core–shell nanocables on Ti/RuO2 + TiO2 substrate (titanium plate covered with RuO2+TiO2 coating). Electrochemical depositions were utilized for constructing this core–shell nanostructure, which involved potentiostastic deposition of ZnO nanorod arrays and potentiodynamic deposition of multivalent and partially hydrous manganese oxide. According to cyclic voltammetry and galvanostatic charge–discharge measurements, ZnO@MnO2 core–shell nanocables electrode exhibits higher specific capacitance and better rate capability than those of pure MnO2 electrode. The specific capacitances of ZnO@MnO2 core–shell nanocables reach 537.8 F g−1 at a scan rate of 5 mV s−1 and 613.5 F g−1 at a current density of 1 A g−1. Electrochemical impedance spectroscopies also confirm that ZnO@MnO2 core–shell nanocables electrode has better electrochemical characteristics. Furthermore, ZnO@MnO2 core–shell nanocables losses 10.2% of the initial capacitance after 5000 charge–discharge cycles, which demonstrates its excellent cycling stability. These results indicate that the electrochemical property of manganese oxide has been greatly enhanced due to the supporting of ZnO nanorod arrays, and ZnO@MnO2 core–shell nanocables is promising electrode material for high-performance supercapacitors.

Preparation and Properties Research of Ag@M<SUB><I>x</I></SUB>O<SUB><I>y</I></SUB> Core–Shell Nanocables

Preparation and Properties Research of Ag@M<SUB><I>x</I></SUB>O<SUB><I>y</I></SUB> Core–Shell Nanocables

Alternative synthesis of cobalt monophosphide@C core–shell nanocables for electrochemical hydrogen production

Cobalt monophosphide@C (CoP@C) core–shell nanocables are successfully synthesized via a one-step fast reaction of cobalt(II) acetylacetonate [Co(acac)2] and triphenyl phosphine (PPh3) in a sealed tube at 400 °C for 1 h. The electrocatalytic property of the CoP@C nanocables towards the hydrogen evolution reaction (HER, for the production of molecular hydrogen from water) has been investigated in the current work and it is found that the CoP@C nanocables exhibit a high electrochemical performance and excellent cycling stability. Moreover, investigations show that the carbon coating ensures a fast electron transport and effective restriction of corrosion during the catalytic process. We believe that the CoP@C nanocables would be promising candidates for electrochemical hydrogen production catalyst.

Highly porous honeycomb manganese oxide@carbon fibers core–shell nanocables for flexible supercapacitors

Core–shell electrodes composed of highly porous honeycomb manganese oxide@carbon fibers (HMO@CFs) are synthesized by a facile hydrothermal approach involving an in situ redox replacement reaction between potassium permanganate (KMnO4) and carbon fibers. In this reaction, the carbon fibers serve as not only a sacrificial reductant, but also the substrate. The porous HMO@CFs core–shell nanocables deliver remarkable electrochemical performance with a high capacitance (295.24Fg−1 at 100mAg−1), high good rate capability, and superior cycling stability (about 96.4% specific capacitance retained after 3000 cycles). The maximum energy density of 22.2Whkg−1 (at a power density of 400Wkg−1) and power density of 12,000Wkg−1 (at an energy density of 10Whkg−1) can be achieved at an operating voltage of 1.6V. The fabrication method is simple, cost-effective, and readily scalable thereby having large commercial potential.

Coaxial carbon nanofiber/NiO core–shell nanocables as anodes for lithium ion batteries

The CNF/NiO core–shell nanocables are prepared by electrospinning and electrophoretic deposition. The CNF/NiO nanocables deliver a high reversible capacity of 825 mA h g−1 at 200 mA g−1 after 50 charge–discharge cycles without showing obvious decay.

Metal–semiconductor Zn/ZnO core–shell nanocables: facile and large-scale fabrication, growth mechanism, oxidation behavior, and microwave absorption performance

Zn/ZnO core–shell nanocables have been fabricated on a large scale and the formation mechanism and microwave absorption properties have been investigated.

Characterization of modified SiC@SiO2 nanocables/MnO2 and their potential application as hybrid electrodes for supercapacitors.

In this research, we demonstrate a simple route for preparing SiC@SiO2 core-shell nanocables and furthermore obtain SiC@SiO2 nanocables/MnO2 as hybrid electrodes for supercapacitors using various modified methods. The modified procedure consists of mild modifications using sodium hydroxide as well as UV light irradiation and deposition of MnO2. The morphology and microstructural characteristics of the composites are investigated using XRD, XPS, FE-SEM with EDS and TEM. The results indicate that the surfaces of modified SiC@SiO2 nanocables are uniformly coated with a MnO2 thin layer. The electrochemical behaviors of the hybrid electrodes are systematically measured in a three-electrode system using cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance spectroscopy. The resultant electrode presents a superb charge storage characteristic with a large specific capacitance of 276.3 F g(-1) at the current density of 0.2 A g(-1). Moreover, the hybrid electrode also displays a long cycle life with a good capacitance retention (∼92.0%) after 1000 CV cycles, exhibiting a promising potential for supercapacitors.

Facile synthesis of Ag nanowires/mesoporous TiO2core–shell nanocables with improved properties for lithium storage

In this paper, the Ag/TiO2coaxial nanocables were successfully fabricated through a facile sol–gel method combined with a hydrothermal treatment process and a short post-annealing procedure. The obtained electrode materials delivered superior electrochemical performance.

Synthesis and fabrication of CNTs/Fe3O4@Pdop@Au nanocables by a facile approach

Multifunctional nanocables were prepared by directly welding superparamagnetic Fe3O4 nanoparticle decorated CNTs and Au nanoparticles together with polydopamine (Pdop) as “glue” in a facile but effective way. Additionally, the size and density of the Au nanoparticles can be easily controlled by different chemical approaches. Moreover, these core–shell nanocables can be a versatile platform for multiple applications.

Selective trimethylamine sensors using Cr2O3-decorated SnO2 nanowires

Pristine SnO2 nanowires (NWs), Cr2O3-decorated SnO2 NWs, and SnO2–Cr2O3 core-shell nanocables (NCs) were prepared by thermal evaporation, and their gas-sensing characteristics were investigated. The decoration of discrete p-type Cr2O3 nanoclusters on SnO2 NWs increased their response to trimethylamine (TMA). Highly sensitive and selective detection of TMA was attributed to the chemical affinity and catalytic activity of Cr2O3 toward TMA. In contrast, the SnO2–Cr2O3 NCs, formed by the coating of a continuous p-type Cr2O3 overlayer on SnO2 NWs, showed negligibly low responses to all analyte gases used. The variations in gas-sensing characteristics due to configuration changes in one-dimensional SnO2–Cr2O3 hetero-nanostructures are explained and discussed in relation to the gas-sensing mechanisms of n- and p-type oxide semiconductors.

Propagation and enhancement of ultraviolet radiation in metal–dielectric nanocables assisted by surface plasmon polaritons

Zn/Zn2SiO4 core–shell nanocables are convenient to grow and have ability to carry ultraviolet (UV) information, which makes them a promising structure in the future application, the nano-waveguide amplifier. In this study, the propagation and enhancement characteristics of surface plasmon polaritons in metal–dielectric core–shell nanocables are experimentally and theoretically studied. The strong coupling effect is also determined. The results demonstrate that UV signals can be effectively transmitted and significantly enhanced in the nanocables.

Hydrogenated ZnO Core–Shell Nanocables for Flexible Supercapacitors and Self-Powered Systems

Although MnO2 is a promising material for supercapacitors (SCs) due to its excellent electrochemical performance and natural abundance, its wide application is limited by poor electrical conductivity. Inspired by our results that the electrochemical activity and electrical conductivity of ZnO nanowires were greatly improved after hydrogenation, we designed and fabricated hydrogenated single-crystal ZnO@amorphous ZnO-doped MnO2 core-shell nanocables (HZM) on carbon cloth as SC electrodes, showing excellent performance such as areal capacitance of 138.7 mF/cm(2) and specific capacitance of 1260.9 F/g. Highly flexible all-solid-state SCs were subsequently assembled with these novel HZM electrodes using polyvinyl alcohol/LiCl electrolyte. The working devices achieved very high total areal capacitance of 26 mF/cm(2) and retained 87.5% of the original capacitance even after 10 000 charge/discharge cycles. An integrated power pack incorporating series-wound SCs and dye-sensitized solar cells was demonstrated for stand-alone self-powered systems.

Transformation of ZnO Nanobelts into Single-Crystalline Mn3O4 Nanowires

Single-crystalline Mn(3)O(4) nanowires were prepared using the vapor-phase transformation of ZnO nanobelts. Mn(3)O(4)-decorated ZnO nanobelts and ZnO-ZnMn(2)O(4) core-shell nanocables (NCs) were also obtained as reaction intermediates. Heteroepitaxial growth of tetragonal spinel Mn(3)O(4) (or ZnMn(2)O(4)) on wurtzite ZnO is a possible reason for the growth of single-crystalline Mn(3)O(4) nanowires. Growth interfaces are possibly formed between the wurtzite (101[overline]0)/(21[overline]1[overline]0) and spinel (1[overline]01)/(4[overline]11) planes. Various one-dimensional homonanostructures and heteronanostructures consisting of n-ZnO, p-Mn(3)O(4), and p-ZnMn(2)O(4) can be used to design high-performance gas sensors.

Ag/TiO2 core–shell nanocables prepared with a one-step polyol process

One-dimensional (1D) Ag/TiO2 core–shell nanocables have been synthesized with a facile polyol process by reducing AgNO3 and hydrolysis of titanium tetraisopropoxide without the need for any templates and capping agents under atmospheric conditions. The morphology of the Ag/TiO2 core–shell nanocables produced in this way is as either linear or spiral particles. The former are composed of an Ag rod core, and the later are aggregates of Ag nanoparticles which are aligned into an ID structure. The nanocables are about 50 and 150 nm in diameter for the linear and spiral particles, respectively, and over 30 μm in length. The absorption peaks of these Ag/TiO2 core–shell nanocables are significantly red-shifted comparing with those of uncoated pure silver nanowires. On the basis of the experimental results, a micro-reactor oxide template mechanism has been proposed to explain the growth of Ag/TiO2 core–shell nanocables.

Free-standing open-ended TiO2 nanotube membranes and their promising through-hole applications

Free-standing open-ended TiO2 nanotube membranes were fabricated by raising voltage for a short time at the end of anodization process. Benefiting from its semiconducting nature and distinctive through-hole structure, the applications of open-ended TiO2 nanotube membranes on flow-through photocatalysis and nanoreactor were demonstrated. As for flow-through photocatalysis, the photocatalytic property of TiO2 is beneficial to reduce the concentration of RhB solution during RhB molecules diffuse through open-ended TiO2 nanotube membrane. As for nanoreactor application, CdS@TiO2 core–shell nanocables were successfully fabricated by a simple paired-cell reaction. A possible formation mechanism for the growth of core–shell structure was discussed on the basis of a series of electron microscopy characterization results. In addition, we evaluated the photocatalytic activity of CdS@TiO2 samples synthesized at different reaction time through the degradation of rhodamine B under simulated sunlight irradiation. It was found that the CdS@TiO2 samples synthesized at 24h exhibited about 100% enhanced photocatalytic activity as compared to bare TiO2 nanotubes, while the CdS@TiO2 samples synthesized at 48h (core–shell nanocables) had the equivalent photocatalytic activity to the bare TiO2 nanotubes. Such behavior that the photocalytic activity changes with CdS loading amount results from a compromise between a larger amount of light absorption and a lower efficiency of charge separation, as well as limited diffusion by channel blocking higher degree of CdS loading.

Nanoscale integration of SiC/SiO2 core-shell nanocables in diamond through a simultaneous hybrid structure fabrication

The nanoscale integration of SiC nanocables in a diamond thin film is achieved through a novel synthetic pathway, which combines Fe catalyst and detonation nanodiamond seeding technique in a microwave plasma chemical vapor deposition process. The obtained hybrid structures show controllable SiC nanocable fraction depending on the relative fraction of iron catalyst and diamond seeds. The SiC nanocable has a conical structure with 10 nm diameter SiC core, surrounded by SiO2 shell. The diamond crystals show high quality/crystallinity even for hybrid structures featuring an increasing SiC nanocable fraction. In the end, the growth behavior of the hybrid structure is discussed.

One-pot synthesis of Bi-Ni nanowire and nanocable arrays by coelectrodeposition approach

A novel and convenient one-pot electrodeposition approach has been developed for precisely controlled fabrication of large-scale Bi-Ni nanowire and nanocable arrays. Using porous anodic aluminum oxide as a shape-directing template, by simply changing the electrochemical deposition mode, desired Bi-Ni hybrid nanowires and Bi-Ni core-shell nanocables have been obtained in the CV and CC modes, respectively. The structure, morphology, and composition of the as-prepared samples were characterized using X-ray powder diffraction, transmission electron microscopy, elemental mapping, and energy-dispersive X-ray spectrometry.