Multilayer Nanotubes Research Articles

Review of: "Electrically conductive graphene nanoribbons in the structure of multi-layer and single-layer nanotubes show signs of ballistic transport"

Review of: "Electrically conductive graphene nanoribbons in the structure of multi-layer and single-layer nanotubes show signs of ballistic transport"

Elevating photocatalytic H2 evolution over ZnIn2S4@Au@Cd0.7Zn0.3S multilayer nanotubes via Au-mediating H–S antibonding-orbital occupancy

Metal sulfides have been considered as an important category of photocatalysts for photocatalytic hydrogen evolution because of their low cost, simple preparation process and abundance of active sites. However, the atomic hydrogen is generally adsorbed on the sulfide photocatalysts to form strong H–S bond, which impedes the release of generated H2 molecules from the photocatalyst surface, severely limiting the H2 evolution efficiency. To address this issue, herein we have designed an interesting type of ZnIn2S4@Au@Cd0.7Zn0.3S (ZIS@Au@CZS) multilayer nanotubes with Au medium sandwiched between inner CZS layer and outer ZIS layer. The Au medium serves as the electron mediator to provide free electrons to fill the H–S antibonding orbitals in CZS and ZIS; this process decreases the adsorption capability of the S sites towards atomic hydrogen, thus facilitating the release of generated H2 molecules. This study provides an important guidance for modifying the photocatalysts to maximize their photocatalytic H2 evolution.

Fabrication and regulation of self-assembled nanostructures of benzene-1,3,5-tricarboxamide derivatives

A variety of supramolecular structures of benzene-1,3,5-tricarboxamide derivatives (BTAs), such as helixes and nanosheets, have been fabricated. However, how to regulate the self-assembly behavior through molecular design and control of experimental conditions, and thus to form supramolecular structures with different morphologies is still a topic that needs to be further explored. In this paper, two kinds of BTAs with different end groups, i.e. terpyridine and carboxyl were synthesized, which are referred to as L and A, respectively. Their self-assembly behaviors in DMF/aqueous solution were investigated by adding the DMF solution of BTAs into the aqueous solution dropwise. It was found that the two BTAs exhibited different self-assembly behaviors. L self-assembled into helical nanowires and nanosheets in the mixed media at lower and higher metal ion concentrations. However, A formed multilayer vesicles and nanotubes at lower and higher concentrations of A molecules. Such a difference was ascribed to their different molecular structures and therefore the different amphiphilicity. The more hydrophobic L molecules could escape from DMF droplets and self-assembled with the help of supramolecular interactions. The more amphiphilic A molecules were prone to adsorb at the oil/water interface to form layered films. The relative strength of coordination interaction determined the self-assembly behavior of L and the formation of helical nanowires and nanosheets, and the packing mode of A molecules at the oil/water interface determined the formation of vesicles and nanotubes. In addition, the formed vesicles of A were responsive to pH.

Implantation of Gallium into Layered WS2 Nanostructures is Facilitated by Hydrogenation.

Bombarding WS2 multilayered nanoparticles and nanotubes with focused ion beams of Ga+ ions at high doses, larger than 1016 cm-2, leads to drastic structural changes and melting of the material. At lower doses, when the damage is negligible or significantly smaller, the amount of implanted Ga is very small. A substantial increase in the amount of implanted Ga, and not appreciable structural damage, are observed in nanoparticles previously hydrogenated by a radio-frequency activated hydrogen plasma. Density functional calculations reveal that the implantation of Ga in the spaces between adjacent layers of pristine WS2 nanoparticles is difficult due to the presence of activation barriers. In contrast, in hydrogenated WS2, the hydrogen molecules are able to intercalate in between adjacent layers of the WS2 nanoparticles, giving rise to the expansion of the interlayer distances, that in practice leads to the vanishing of the activation barrier for Ga implantation. This facilitates the implantation of Ga atoms in the irradiationexperiments.

Flexible Strain Sensors Based on Bionic Parallel Vein-like Structures for Human Motion Monitoring.

In recent years, strain sensors have penetrated various fields. The capability of sensors to convert physical signals into electrical signals is of great importance in healthcare. However, it is still challenging to obtain sensors with high sensitivity, large operating range and low cost. In this paper, a stretchable strain sensor made of a double-layer conductive network, including a biomimetic multilayer graphene-Ecoflex (MLG-Ecoflex) substrate and a multilayer graphene-carbon nanotube (MLG-CNT) composite up-layer was developed. The combined action of the two layers led to an excellent performance with an operating range of up to 580% as well as a high sensitivity (gauge factor (GFmax) of 1517.94). In addition, a pressure sensor was further designed using the bionic vein-like structure with a multi-layer stacking of MLG-Ecoflex/MLG-CNT/MLG-Ecoflex to obtain a relatively high deformation along the direction of thickness. The device presented a high sensing performance (up to a sensitivity of 0.344 kPa-1) capable of monitoring small movements of the human body such as vocalizations and gestures. The good performance of the sensors together with a simple fabrication procedure (flip-molding) make it of potential use for some applications, for example human health monitoring and other areas of human interaction.

Designed Synthesis of Cu2O Quantum Dots/TiO2 Nanotubes Heterostructure as a Photocatalyst for Converting CO2 to CH4

Herein, H+ in oxalic acid is used instead of Na+ to obtain titanate nanosheets through P200 hydrolysis, which further curls to form a multilayer TiO2 nanotubes (NTs) structure. Then, Cu2O quantum dots (QDs) are successfully loaded on TiO2 NTs via a hydrothermal method using fructose as a reducing agent. The optical, impedance, and photocurrent tests indicate that the composite structure improves its optoelectronic performance. The photocatalytic H2 production and CO2 reduction efficiency of Cu2O QDs/TiO2 NTs are lower than those of TiO2 NTs. However, the molar ratio of CH4 to CO produced by CO2 reduction of Cu2O QDs/TiO2 NTs composite catalyst is greater than that of pure TiO2 NTs. The CH4 production accounts for 97%, indicating that the composite catalyst has a high CH4 selectivity. The experimental and density functional theory calculation results prove that the Z‐scheme heterojunction accelerates the separation and transfer of photogenerated carriers, and broadens the absorption range of visible light.

Silk-protein-based gradient hydrogels with multimode reprogrammable shape changes for biointegrated devices

Biocompatible and morphable hydrogels capable of multimode reprogrammable, and adaptive shape changes are potentially useful for diverse biomedical applications. However, existing morphable systems often rely on complicated structural designs involving cumbersome and energy-intensive fabrication processes. Here, we report a simple electric-field-activated protein network migration strategy to reversibly program silk-protein hydrogels with controllable and reprogrammable complex shape transformations. The application of a low electric field enables the convergence of net negatively charged protein cross-linking networks toward the anode (isoelectric point plane) due to the pH gradient generated in the process, facilitating the formation of a gradient network structure and systems suitable for three-dimensional shape change. These tunable protein networks can be reprogrammed or permanently fixed by control of the polymorphic transitions. We show that these morphing hydrogels are capable of conformally interfacing with biological tissues by programming the shape changes and a bimorph structure consisting of aligned carbon nanotube multilayers and the silk hydrogels was assembled to illustrate utility as an implantable bioelectronic device for localized low-voltage electrical stimulation of the sciatic nerve in a rabbit.

Non-Thermal Plasma Pyrolysis of Fuel Oil in the Liquid Phase

A pulsed plasma pyrolysis reactor with an efficient control system was designed for fuel oil processing. Non-thermal plasma pyrolysis was carried out in the liquid phase at low temperatures (not higher than 100 °C) in a 300 cm3 reactor without additional reagents or catalysts. The main process parameters and characteristics of non-thermal plasma fuel oil products were investigated within the DC source voltage range of 300–700 V. An increase in the energy of pulsed discharges led to an increase in the productivity of the plasma pyrolysis process and the yield of hydrogen but reduced the yield of acetylene and ethylene. The resulting gas consisted predominantly of hydrogen (46.5–50.0 mol%), acetylene (28.8–34.3 mol%), ethylene (7.6–8.6 mol%), methane (4.2–6.2 mol%), and C3–C5 hydrocarbons. The solid-phase products were in the form of disordered graphite and multilayer nanotubes.

From multi-segmented to core/shell nanorods: morphology evolution in Fe–Au nanorods by tuning fabrication conditions

Aiming to obtain hybrid magneto-plasmonic nanostructures, we have developed multisegmented and core/shell structured Fe–Au nanorods using template assisted electrochemical deposition. A facile method of tuning the growth pattern of multisegmented nanorods into core/shell structured is demonstrated. With a precise control of current density and deposition time, a brick-stacked wire like growth led to the formation of hollow nanotubes that could be further tuned to multilayered hollow nanotubes and core/shell structured nanorods. TEM imaging and STEM-EELS technique were used to explore the morphology, microstructure and the distribution of Au and Fe in the nanorods. The easy magnetization direction was found to be perpendicular to the nanorods’ growth direction in the segmented nanorods. On the other hand, core/shell nanorods exhibited isotropic behavior. Our findings provide deeper insights into the fabrication of hybrid nanorods and the opportunity to tune the fabrication method to vary their morphology accordingly. Such studies will benefit design of hybrid nanorods with specific morphologies and physical properties and hence their integration into sensing, spintronics and other potential biomedical and technological applications.

Enhanced Faradaic Capacitance in High-Performance Asymmetric Supercapacitor Device by Nickel Sites Encapsulated in Multilayered Nanotube

Enhanced Faradaic Capacitance in High-Performance Asymmetric Supercapacitor Device by Nickel Sites Encapsulated in Multilayered Nanotube

High-performance asymmetric supercapacitor device with nickel–cobalt bimetallic sites encapsulated in multilayered nanotubes

Assembled ASC and corresponding red LED lightning via connection of two ASCs in series.

Investigation of the Effect of Supersonic Flow of Dissociated Nitrogen on ZrB2-HfB2-SiC Ceramics Doped with 10 vol.% Carbon Nanotubes.

The method of fabricating dense ultra-high temperature ceramic materials ZrB2−HfB2−SiC−CCNT was developed using a combination of sol-gel synthesis and reaction hot pressing approaches at 1800 °C. It was found that the introduction of multilayer nanotubes (10 vol.%) led to an increase in the consolidation efficiency of ceramics (at temperatures > 1600 °C). The obtained ZrB2−HfB2−SiC and ZrB2−HfB2−SiC−CCNT materials were characterized by a complex of physical and chemical analysis methods. A study of the effects on the modified sample ZrB2−HfB2−SiC−CCNT composition speed flow of partially dissociated nitrogen, using a high-frequency plasmatron, showed that, despite the relatively low temperature established on the surface (≤1585 °C), there was a significant change in the chemical composition and surface microstructure: in the near-surface layer, zirconium−hafnium carbonitride, amorphous boron nitride, and carbon were present. The latter caused changes in crucial characteristics such as the emission coefficient and surface catalyticity.

Nanoarchitectonics of Ag-modified g-C3N4@halloysite nanotubes by a green method for enhanced photocatalytic efficiency

In this study, a facile and cost effective green synthesis has been utilized for the synthesis of silver nanoparticles (Ag-NPs)–modified graphitic carbon nitride (Ag-g-C3N4) and halloysite nanotubes (HNTs) using Centella Asiatica (L.) extract, urea and mineral source of natural halloysite (HNTs), respectively. Here, silver ions (Ag+) were reduced to Ag-NPs using an aqueous Centella Asiatica (L.) as reducing and capping agent. The synthesized Ag-g-C3N4@HNTs were characterized by various physiochemical methods such as XRD, FT-IR, BET, SEM, TEM, EDS–mapping, UV–vis-DRS, PL, XPS and EPR methods. In the photocatalytic experiment, Ag-g-C3N4@HNTs nanocomposite with silver surface plasmon resonance of Ag-NPs and multi-layer hollow nanotubes was outperformed by the individual components. With an in-depth study on the photocatalytic mechanisms, we can conclude that the enhanced performance of the nanocomposite is due to the effective separation of photogenerated electrons and superoxide radicals (•O2–) in water molecules. The photocatalyst preserved excellent photostability for up to four cycles (with a minor activity reduction from 95% to 91%). These results demonstrated the development of novel semiconductors from inexpensive resources with effective photoactivity to mitigate environmental problems.

The mechanics and design of a local crystallization of amorphous for carbon material by molecular dynamics simulation

Achieving high strength and plasticity by means of microstructure manipulation of three-dimensional carbon material attracts researchers’ attention. This work is primarily on the influence of sp2 content at micro and molecular level on mechanical properties by molecular dynamics simulation. Additionally, the influence of interfaces has been investigated by three multi-nanocapsule pillars assembled with the equiaxed amorphous models. The model that has the best fit between strength and plasticity we obtained is the amorphous model with 100% multi-layer nanotubes fragments, and with no interfaces. We found that the rotating and folding of fragments are the main microscopic deformation mechanisms of amorphous carbon materials with sp2 fraction decreasing attributed to the breaking of covalent bonds, which has also been verified in experiment. The rotation of the nanocapsule and the migration of the interface contribute more in the condition of the existence of interfaces in the amorphous carbon material.

Nonthermal plasma in the induction of polycondensation processes and intermolecular dehydrochlorination of chloroethanes in the liquid phase

AbstractThe nonthermal plasma treatment of 1,2‐dichloroethane, 1,1,2‐trichloroethane, and 1,1,2,2‐tetrachloroethane in the liquid phase leads to the formation of unsaturated chlorine derivatives of hydrocarbons, nanostructures, and hydrogen chloride. In the case of nonthermal plasma‐induced elimination of chloroethanes, the main products are: chloroethene from 1,2‐dichloroethane, 1,1‐dichloro‐, 1,2‐dichloroethene from trichloroethane, and trichloro‐ and tetrachlorethylenes from tetrachloroethane. Solid products are presented in the form of nanoscale carbon structures—multilayer nanotubes, carbon fibers, graphene layers, and others. Quantum‐chemical calculations show that the elimination of HCl under the nonthermal plasma treatment on chloroethanes occurs intermolecularly.

Structural, Morphological, Topographical Characterization of Titanium Dioxide Nanotubes Metal Substrates for Solar Cell Application

High demand on energy conversion in DSSC, requires development of well-organized TiO2 nanotube structures because of their large surface area-to-volume ratio, superior lifetime and provision of optimal pathways for electron percolation. In this work multi-layered Titanium dioxide nanotubes (MTNTs) have been fabricated by an electrochemical anodization technique. MTNTs were annealed at 350‚°C, 450‚°C, 550‚°C and 650‚°C. The structural and morphological properties of the MTNTs have been evaluated by XRD, Confocal Raman Microscopy (CRM) through Large Area Scan (LAS), Depth Profiling (DP) and SEM analysis. SEM-EDX has been employed for element elucidation of TNTs. SEM analysis has revealed the change in surface with increase in annealing temperature. Moreover SEM analysis has revealed the presence of porous and MTNTs for the samples annealed at 350‚°C and 650‚°C with modal pore size of 35.56 nm and 31.05 nm respectively. EDX analysis has revealed that the fabricated MTNTs consist of Ti and O atoms. CRM has confirmed the presence of Anatase phase TiO2 with Raman vibration modes at 142.37 cm-1, 199.04 cm-1, 394.67 cm-1, 516.16 cm-1 and 639.29 cm-1with the Rutile phase TiO2 with Raman vibration modes at 445.26 cm-1 and 612.07 cm-1. The XRD analysis has revealed that the MTNTs consist of multiphase Anatase and Rutile phase depending on the annealing temperature. AFM has confirmed the existence of porous nano-tubular structure for all samples.

Inorganic fullerene-like nanoparticles and nanotubes of tungsten disulfide as reinforcement of carbon-epoxy composites

A possibility was examined to enhance carbon-epoxy laminated composite mechanical properties by introducing a small concentration of reinforcing nanostructures – multi-wall onion-shaped fullerene-like nanoparticles of tungsten disulfide IF-WS2, and its multi-layer hollow nanotubes, INT-WS2, both known for their outstanding thermal, chemical, and mechanical resistance. Composite structures were prepared using a unidirectional prepreg of strong carbon fibers and epoxy resin, poly (vinyl butyral) solution in ethanol with ultrasonically dispersed WS2 nanostructures in it. Particle size analysis has been performed to evaluate the quality of IF-WS2 nanoparticles. SEM/EDS analysis was applied to observe the nanostructures, their dispersion in the composite, and the fracture zone after mechanical resistance tests of the prepared composite samples. Thorough mechanical tests were performed on a set of specimens with different fiber orientations: tensile test, bending test, and interlaminar shear test. The encouraging results were obtained, indicating that these newly designed light-weight composites are applicable for the automotive and nautical industry, unmanned aerial vehicles, and military aircrafts.

Characterization of Molecular Spacer-Functionalized Nanostructured Carbons for Electrical Energy Storage Supercapacitor Materials

The use of molecular spacers between Carbon Nanotubes (CNTs) has been shown to increase the ion-accessible surface area for use in supercapacitor materials. Maintaining porosity and electrical conductivity is important for maximizing capacitance, energy storage, and power. Two reported novel coordination complexes have shown exceptional Faradaic charge transfer and binding capabilities to prevent CNT aggregation. Dispersion stability measurements show less aggregation of HiPco Single Walled CNTs (SWCNTs) compared to other chirality and multilayered nanotubes. Cu2FcOH binds weakly to CNTs compared +2Zn2 and +2Ru2 due to Columbic electrostatic interactions, which is favorable because it does not collapse the electrical double layer as strongly as +2Zn2 or +2Ru2. Adsorption isotherms and a full characterization (1H NMR, ATR FT-IR, UV-Vis, CV) of these novel complexes are presented. Electrical characterization using CV, charge discharge, and electrochemical impedance spectroscopy and the supercapacitor performance of functionalized thin film electrodes are presented as a function of spacer properties and nanostructured carbon tube diameter. This study uses rigid, earth-abundant coordination complexes that bind to and intercalate between SWCNTs. These functionalized nanostructured carbons are then used to make electrodes for electrical double layer supercapacitors. A complete description of the synthesis, characterization, and processing of these materials is described.

Influence of Carbon Nanomodifier on the Structure and Properties of the Modified Gypsum Binder

Water-soluble polymer and latex additives are used to give the gypsum building plaster elasticity and placeability, improved water resistance and increased bending strength. The nanomodifiers in the form of carbon single-layer and multi-layer nanotubes, fullerenes and other nanoparticles are used for the formation of the structure of a gypsum stone with improved strength characteristics and improved weather resistance. In this work, the joint effect of the plasticizer based on polycarboxylate and the carbon nanomodifier on the structure, physicomechanical properties, and water resistance of the gypsum stone is investigated. It is shown that nanomodifiers contribute to the increase in the plasticizing ability of carboxylate additives, which leads to the significant decrease in the amount of mixing water, and as a result, to the increase in density, decrease in the porosity of the gypsum stone and the increase in its strength characteristics and water resistance.

Nanocomposite Polymeric Materials Based on Eucalyptus Lignoboost® Kraft Lignin for Liquid Sensing Applications.

This study reports the synthesis of polyurethane–lignin copolymer blended with carbon multilayer nanotubes to be used in all-solid-state potentiometric chemical sensors. Known applicability of lignin-based polyurethanes doped with carbon nanotubes for chemical sensing was extended to eucalyptus LignoBoost® kraft lignin containing increased amounts of polyphenolic groups from concomitant tannins that were expected to impart specificity and sensitivity to the sensing material. Synthesized polymers were characterized using FT-MIR spectroscopy, electrical impedance spectroscopy, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry and are used for manufacturing of all solid-state potentiometric sensors. Potentiometric sensor with LignoBoost® kraft lignin-based polyurethane membrane displayed theoretical response and high selectivity to Cu (II) ions, as well as long-term stability.