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Self-Improving Na Ion Storage in Oxygen Deficient, Carbon Coated Self-Organized TiO <sub/>2</sub> Nanotubes
摘要： The development of sodium ion batteries is largely motivated by the growing cost and limited resources of lithium. Titanium dioxide (TiO2), in the form of self-organized and well-oriented nanotube arrays, are considered as a highly attractive anode material for sodium ion batteries, due to their inherent safety, low cost and structural stability. This work reports on the sodiation and desodiation characteristics of anodically grown, self-organized TiO2 nanotubes annealed in an Ar/C2H2 atmosphere (TiO2-x-C). It is found that anatase TiO2-x-C nanotubes demonstrate substantial self-improving charge storage capacities as cycling proceeds, leading to a specific capacity of 202.2 ± 50.6 mAh g-1 at a current rate of 30 mA g-1 (C/20). Subsequent kinetic analysis reveals a pseudocapacitive contribution which dominates the Na storage process in TiO2-x-C nanotubes at fast sodiation rates. This pseudocapacitance in TiO2-x-C nanotubes is found to enable exceptional high-rate capabilities with a specific capacity of 58.4 ± 14.6 mAh g-1 at a current rate of 12 A g-1 (20C).
关键词： nanotubes,Na ion,self-improving,batteries,titanium dioxide
更新于2025-09-23 15:21:01
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Transconductance Amplification in Dirac-Source Field-Effect Transistors Enabled by Graphene/Nanotube Hereojunctions
摘要： Steep-slope devices are predicted to provide excellent quality for analog integrated circuit applications due to their high transconductance efficiency (gm/Ids) breaking the metal-oxide-semiconductor field-effect transistor limit (38.5 V?1). The potential advantage of a Dirac-source FET (DSFET) as an analog transistor is explored based on a graphene/carbon nanotube (CNT) heterojunction. A high gm/Ids beyond 38.5 V?1 over four decades of current is experimentally demonstrated in an individual CNT-based DSFET, reaching a peak value of 66 V?1, which is a new record for all reported transistors. Importantly, this high gm/Ids extends beyond the subthreshold region and leads to transconductance amplification in the overthreshold region. The best peak transconductance at a low bias of ?0.1 V exceeds 20 μS per tube, which has approximately threefold improvement over that of a normal CNT FET with a shorter gate length. Outperforming other advanced devices, the extended high transconductance efficiency greatly promotes DSFET competitiveness in the high-precision analog field.
关键词： carbon nanotubes,heterojunctions,Dirac sources,graphene,field-effect transistors
更新于2025-09-23 15:21:01
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ZnO/Ag NANOPARTICLE-DECORATED SINGLE-WALLED CARBON NANOTUBES (SWCNTs) AND THEIR PROPERTIES
摘要： Raw single-walled carbon nanotubes (SWCNTs) were oxidized by using sulfuric acid and nitric acid at 3:1 ratio to produce oxygen functional groups attached to SWCNTs surfaces. Then, the oxidized SWCNTs are coated with zinc oxide and silver nanoparticles by chemical precipitation route to synthesize ZnO/Ag-SWCNTs nanocomposite material. The nanocomposite sample was analyzed via zeta potential analyzer, ultraviolet-visible (UV-Vis) spectrophotometer, ˉeld emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), X-ray di?raction (XRD), and Raman spectroscopy to investigate colloidal stability, optical, morphological, and structural properties. The SWCNT properties were found to be changed after the addition of ZnO/Ag nanoparticles. Hence, the new ZnO/Ag-SWCNTs nanocomposite is a good candidate for photocatalyst applications and biological applications.
关键词： biological applications,photocatalyst applications,Single-walled carbon nanotubes (SWCNTs),ZnO/Ag nanocomposite,chemical precipitation
更新于2025-09-23 15:21:01
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Nonresonant Polarized Raman Spectra Calculations of Nitrogen-Doped Single-Walled Carbon Nanotubes: Diameter, Chirality, and Doping Concentration Effects
摘要： Raman spectra of nitrogen-doped single-walled carbon nanotubes are calculated using the spectral moment’s method combined with the bond polarizability model. The influence of the nanotube diameter and chirality is investigated. We also address the important question of the effect of the N-doping concentration, and we propose an equation to estimate the doping concentration from the knowledge of the tube diameter and the frequency of the radial breathing mode.
关键词： spectral moment’s method,Raman spectra,N-doping concentration,nanotube diameter,nitrogen-doped single-walled carbon nanotubes,bond polarizability model,chirality
更新于2025-09-23 15:21:01
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The effects of growth TiO <sub/>2</sub> nanotubes on forged Ti <sub/>6</sub> Al <sub/>4</sub> V alloy and selectivelaser sintered Ti <sub/>6</sub> Al <sub/>4</sub> V alloy surfaces for environment and medical applications
摘要： The paper describes the effect of growth TiO2 nanotubes on titanium surfaces by anodic oxidation for environmental and medical applications. The importance of the metallurgical state of TiAl6V alloy on the growing of TiO2 nanotubes by anodization will be highlighted. Starting from the possibility of obtaining the TiO2 nanotubes, the paper presents results on TiO2 nanotubes grown by electrochemical anodization method, using a solution containing HF 0,4% and having as electrodes, graphite as cathode and titanium alloy specimens obtained by two technologies: by cold plastic deformation as well as by additive manufacturing process SLS, as anode. So, the nanotubes were produced by anodization and analysed by scanning electron microscopy. The aim of this paper is to compare the electrochemical formation of TiO2 on the surface of both specimens knowing that the titanium alloys and its oxides are used in many biomedical and environmental applications, thus providing the importance of nanotubes and the fact that their properties open doors in these fields.
关键词： medical applications,TiO2 nanotubes,environmental applications,anodic oxidation,Ti6Al4V alloy
更新于2025-09-23 15:21:01
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Variance Spectroscopy Studies of Single-Wall Carbon Nanotube Aggregation
摘要： Early stages of single-wall carbon nanotube aggregation in aqueous surfactant suspension have been investigated through combined structure-resolved fluorescence and variance spectroscopies. Following the addition of NaCl to destabilize dispersed samples, variance data revealed strong decreases in the concentrations of emitting particles, while fluorescence spectra showed only modest changes. This indicates the formation of loose aggregates in which electronic contact between individual nanotubes is too limited to perturb their emission. Variance data showed that the initial formation rates of homoaggregates (clusters of the same (n,m) species) increase superlinearly with NaCl concentration. Co-variance analysis gave complementary structure-resolved data on emissive heteroaggregates. For both types of clusters, it is found that the initial aggregation rates correlate with species particle concentrations, but show no clear dependence on nanotube structure. Variance spectroscopy can sensitively detect and characterize small loose clusters of carbon nanotube that are not observable by other spectroscopic methods.
关键词： heteroaggregates,homoaggregates,aggregation,fluorescence spectroscopy,variance spectroscopy,single-wall carbon nanotubes
更新于2025-09-23 15:21:01
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A Predictive Model for the Electrical Transport Within Nanowire Networks
摘要： Thin networks of high aspect ratio conductive nanowires can combine high electrical conductivity with excellent optical transparency, which has led to a widespread use of nanowires in transparent electrodes, transistors, sensors, and ?exible and stretchable conductors. Although the material and application aspects of conductive nanowire ?lms have been thoroughly explored, there is still no model which can relate fundamental physical quantities, like wire resistance, contact resistance and nanowire density, to the sheet resistance of the ?lm. Here we derive an analytical model for the electrical conduction within nanowire networks based on an analysis of the parallel resistor network. The model captures the transport characteristics and ?ts a wide range of experimental data, allowing for the determination of physical parameters and performance limiting factors, in sharp contrast to the commonly employed percolation theory. The model thus constitutes a useful tool with predictive power for the evaluation and optimization of nanowire networks in various applications.
关键词： nanowires,electrical transport,model,percolation,carbon nanotubes,nanowire network,silver nanowires
更新于2025-09-23 15:21:01
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Application of Nanostructured Tungsten Fabricated by Helium Plasma Irradiation for Photoinduced Decolorization of Methylene Blue
摘要： The dendritic nanostructure was fabricated on a surface of tungsten plate by helium plasma irradiation. The nanostructure consisting of W metal was partially oxidized to form WO3 on exposure to air, and the resulting surface exhibited a broad photoabsorption in the range from 1 to 5 eV. We examined photoinduced reaction of methylene blue (MB) on the material. It was found that the partially and fully oxidized surface nanostructures were able to promote a decolorization of MB under photoirradiation even with the near-infrared light (< 1:55 eV), whose energy is lower than the band gap of WO3. The reaction rate was varied with the fraction of W and WO3 on the surface layers, that is, the partially oxidized sample promoted the reaction at a higher rate than the fully oxidized one. It is also found that the reaction rate decreased with time, which would be caused by the products accumulation on the surface and the surface oxidation.
关键词： Scanning electron microscopy (SEM),Tungsten oxide,Surface photochemistry,Plasma processing,Nano-wires, quantum wires, and nanotubes,Visible/ultraviolet absorption spectroscopy, X-ray photoelectron spectroscopy
更新于2025-09-23 15:21:01
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AIP Conference Proceedings [Author(s) 3RD INTERNATIONAL SCIENCES, TECHNOLOGY & ENGINEERING CONFERENCE (ISTEC) 2018 - MATERIAL CHEMISTRY - Penang, Malaysia (17–18 April 2018)] - Synthesis of gold nanoparticles (AuNPs) onto anodized titania nanotubes (TNTs) by spin coating technique
摘要： Gold nanoparticles (AuNPs) have received copious interests due to their unique properties such as small in size, reactive, high surface area and can be potentially applied in myriad fields including physics, chemistry, medicine and material sciences. However, the nanosized of gold particles makes them very reactive and undergo aggregation without protection. For that reason, supporting materials are introduced to prevent the aggregation of the AuNPs. In particular, metal oxide for example, titanium dioxide or titania nanotubes (TNTs) has been used as a support material because of its inertness, high porosity and great surface areas. Nevertheless, achieving precise control of attachment AuNPs on the TNTs substrate by conventional methods such as thermal evaporation and conservative heating are far from satisfactory. Herein, in this work, a new approach has been developed to synthesize controlled and uniformed attachment of AuNPs onto fabricated electrochemically-anodized TNTs by a spin coating technique. This preliminary work used different spin rate of 500, 1000 and 2000 revolutions per minute (rpm), following by heat treatment at 250 °C for 2 hours. The FESEM micrograph showed the anodized TNTs with good morphological structures were successfully fabricated at a voltage of 50 V in a mixture of ethylene glycol containing 0.5 wt. % ammonium fluoride solution, with an average nanotubes diameter of 150 nm. Meanwhile, the attachment of AuNPs on the fabricated TNTs has been effectively achieved at a higher spin rate of 2000 rpm and the EDX analysis confirmed the deposition of AuNPs over the TNTs. The AuNPs-TNTs also were tested for the catalytic reduction of p-nitrophenol (p-NP), in which is discussed shortly in this paper.
关键词： Gold nanoparticles,spin coating,titania nanotubes,electrochemical anodization
更新于2025-09-23 15:21:01
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Plasmon-Assisted Energy Transfer in Hybrid Nanosystems
摘要： While direct optical excitation of carbon nanotubes activates only the tube species strictly matching the excitation source, excitation energy transfer processes provide a single excitation channel for all the nanotubes species in a sample. The requirement of an overlap between donor emission and acceptor absorption limits the poll of donors able to trasfer their excitation to the tubes, leaving the high-energy part of the solar spectrum excluded from such processes. Here it is shown that the grafting of small metal nano-particles to the tubes alters those rules, enabling energy transfer process from molecules for which the standard energy transfer process is strongly suppressed. The onset of an energy transfer band in the UV/blue spectral region is demonstrated for an hybrid gold-pyrene-nanotube system, yielding collective emission from all the tubes present in our samples upon excitation of pyrene.
关键词： gold nanoparticles,pyrene dye,carbon nanotubes,plasmonic hybrids,energy transfer
更新于2025-09-23 15:21:01