Decorated Carbon Nanotubes Research Articles

Enhanced water-selective performance of dual-layer hybrid membranes by incorporating carbon nanotubes

Water-selective membranes are utilized in many fields such as wastewater treatment, desalination, organic solvent dehydration. In this study, dual-layer hybrid membranes were designed and prepared through electrostatic interactions for ethanol dehydration. The polyethyleneimine (PEI) with carboxyl decorated carbon nanotubes (CNT-C) was spin-coated on porous hydrolyzed polyacrylonitrile (HPAN) substrate as one active layer and then coated with sodium alginate (Alg) layer as another active layer. The hydrophobic outside surface of CNT-C provided the abundant paths for the fast water transport, which facilitated the water permeation. Meanwhile, the incorporated CNT-C increased the surface roughness and enhanced the hydrophilicity of the membranes. PEI improved the dispersion of CNT and interfacial compatibilities within membranes. The resultant dual-layer hybrid membranes acquired enhanced separation performance when utilized for pervaporation dehydration of 90 wt% ethanol aqueous solution. The permeation flux was increased by 15% to 2825 g/(m2h) and the separation factor was increased by 1.70 times to 2148, compared with the Alg/PEI/HPAN membrane.

Temperature-controlled in situ synthesized carbon nanotube-protected vanadium phosphate particle-anchored electrospun carbon nanofibers for high energy density symmetric supercapacitors

Designing a novel composite material with hierarchical nanostructures as a negative electrode material with high capacitance and outstanding stability is challenging. To this end, we synthesized carbon nanotubes (CNTs)-protected vanadium phosphate (VPO) nanoparticles trapped within an electrospun carbon matrix (CNTs@VPO@CNFs) for potential use in energy storage applications. Temperature was found to be the major controlling factor for the fabrication of composites with CNT decoration. CNTs@VPO@CNFs exhibited the highest capacitance of 576.1F g−1 at a current density of 0.66 A g−1 among other corresponding electrode materials. Furthermore, this electrode exhibited outstanding stability of up to 99% after 5000 cycles, which was attributed to the coating of core-forming VPO@CNFs by the CNTs as the sheath material. Interestingly, the as-fabricated material worked in a wide potential range from −1.2 to 0.6, thereby providing the opportunity to assemble a symmetric supercapacitor device (SSCD). The SSCD showed an exceptionally high energy density of 69.1 W h kg−1 at a power density of 3.2 kW h and ~ 90% stability after 5000 cycles. Thus, this work presents a strategy for fabricating a new composite as a negative electrode material that can be used in a symmetrical supercapacitor device with an ultrahigh energy density.

Laser-assisted decoration of carbon nanotubes with palladium nanoparticles for application in electrochemical methanol oxidation

Multi-walled carbon nanotubes (MWCNTs) were decorated with palladium nanoparticles (Pd NPs) by laser-ablation of a physical mixture of MWCNTs and Pd NPs without using any reducing agent. The morphology and composition of MWCNT/Pd were analysed by complementary techniques involving Fourier transform infrared spectrometry, transmission electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. Using cyclic voltammetry and chronoamperometry, the electrocatalytic activity and stability of CNT/Pd were evaluated for the electrochemical oxidation of methanol in a basic medium. Comparative investigations were provided with laser-ablated Pd NPs (LA Pd) catalyst concerning catalytic activity and stability. MWCNT/Pd exhibited remarkably high catalytic activity (104.20 mA mg−1) in comparison to the LA Pd catalyst (14.41 mA mg−1). The catalyst was found to exhibit long-term stability even after 3600 s of operation and high resistance towards CO poisoning. It is suggested that the MWCNT/Pd would be valuable as an active electrocatalyst for its commercial applications in direct methanol fuel cells.

Thiol-Amine Functionalized Decorated Carbon Nanotubes for Biomarker Gases Detection

Thousands of gas molecules are expelled in exhaled breath, and some of them can reveal diseases and metabolomic disorders. For that reason, the development of fast, inexpensive, and reliable sensing devices has been attracting growing interest. Here, we present the development of different chemoresistors based on multi-walled carbon nanotubes (MWCNTs) decorated with platinum (MWCNT/Pt) and palladium (MWCNT/Pt) nanoparticles and also functionalized with a self-assembled monolayer (SAM) of 11-amino-1-undecanethiol (Thiol-amine). The nanocomposites developed are a proof-of-concept to detect some biomarker molecules. Specifically, the capability to identify and measure different concentrations of volatile organic compounds (VOCs), either aromatic (toluene and benzene) and non-aromatic (ethanol and methanol) was assessed. As a result, this paper reports the significant differences in sensing performance achieved according to the metal nanoparticle used, and the high sensitivity obtained when SAMs are grown on the sensitive film, acting as a receptor for biomarker vapours.

Facile morphology controllable synthesis of zinc oxide decorated carbon nanotubes with enhanced microwave absorption

The microscopic morphology of the composites has a great influence on their microwave absorbing (MA) performances. However, it remains a challenge to achieve morphology control through a facile way when preparing composites of carbon nanotubes and zinc oxide. In this work, a simple and room-temperature approach is proposed to synthesize zinc oxide/carbon nanotubes (CNT/ZnO) nanocomposites with different microstructures. Changing the type of solvent can lead to different microstructures of CNT/ZnO nanocomposites. This is mainly because of the different ion molar ratio to Zn2+ and OH- in the reaction solution. Besides by adjusting the content of CNT, the microwave absorbing properties of the obtained CNT/ZnO nanocomposites can be controlled. When the CNT content is 10% mass fraction, the minimum reflection loss (RL) of CNT/ZnO-E nanocomposite can reach − 55.42 dB at a thickness of 3 mm. With the increasing weight ratio of CNT, the degree of disorder in the material and the number of the defects increase, 3D conductive networks are easier to form, resulting in the enhanced polarization loss and conductive loss. However, excessive CNTs will cause excessive current induced which is not conducive to electromagnetic wave absorption.

Hierarchical Co3O4/CNT decorated electrospun hollow nanofiber for efficient hybrid capacitive deionization

Hybrid capacitive deionization (HCDI) is emerging as an energy-efficient alternative for brackish water desalination with low expenditure cost and favourable ion removal effectiveness by adopting battery-type electrodes in the traditional capacitive deionization (CDI) system. Herein, an unscalable electrospinning method is introduced to contrive cathode material for HCDI system. Co3O4 and nitrogen-doped carbon nanotube decoration are formed successfully and uniformly distributed with the hollow structure of free-standing carbon nanofibers (Co3O4@CNF@CNT). The conductive “bridges” provided by the CNF matrix significantly shorten the diffusion length of Na+ and promote the electrical conductivity of the Co3O4 nanoparticles. Moreover, benefiting from the incorporation of nitrogen-doped CNTs, the electrical conductivity is further enhanced. The as-prepared Co3O4@CNF@CNT cathode shows excellent pseudocapacitive performance of 395F g−1 at a scan rate of 1 mV s−1 and superior rate performance of 279F g−1 at 100 mV s−1. The HCDI system delivers an outstanding salt adsorption capacity (SAC) of 58.6 mg g−1 and a highest salt adsorption rate (SAR) of 12.27 mg g−1 min−1 with a potential difference of 1.4 V, indicating the great potential of applying Co3O4@CNF@CNT in the practical HCDI system.

High performance flexible energy storage device based on copper foam supported NiMoO4 nanosheets-CNTs-CuO nanowires composites with core–shell holey nanostructure

Because of the intensified electrochemical activities, mixed metal oxides as a representative for pseudocapacitive materials play a key role for high performance supercapacitor electrodes. Nevertheless, low ion and electron transfer rate and poor cycling performance in the electrode practically restrict further promotion of their electrochemical performance. In order to offset the defect, a novel copper (Cu) foam-supported nickel molybdate nanosheet decorated carbon nanotube wrapped copper oxide nanowire array (NiMoO4 NSs-CNTs-CuO NWAs/Cu foam) flexible electrode is constructed. The as-prepared electrode demonstrates a unique core-shell holey nanostructure with a large active surface area, which can provide a large number of active sites for redox reactions. Besides, the CNTs networks supply improved conductivity, which can hasten electron transport. Through this simple and efficient design method, the spatial distribution of each component in the flexible electrode is more orderly, short and fast electron transport path with low intrinsic resistance. As a result, the NiMoO4 NSs-CNTs-CuO NWAs/Cu foam as an adhesiveless supercapacitor electrode material exhibits excellent energy storage performance with high specific areal capacitance of 23.40 F cm−2 at a current density of 2 mA cm−2, which outperforms most of the flexible electrodes reported recently. The assembled asymmetric supercapacitor demonstrates an energy density up to 96.40 mW h cm-3 and a power density up to 0.4 W cm-3 under a working voltage window of 1.7 V. In addition, outstanding flexibility of up to 100° bend and good cycling stability with the capacitance retention of 82.53 % after 10,000 cycles can be obtained.

Stretchable strain sensors with dentate groove structure for enhanced sensing recoverability

Stretchable strain sensors based on conductive polymer composites commonly utilize elastic polymers as the matrix. However, elastic polymers always show strong mechanical hysteresis effect leading to shoulder peak phenomenon and thereby poor recoverability of strain sensors. Herein, we design a stretchable rough filament strain sensor with dentate groove structure to eliminate the shoulder peak phenomenon and improve recoverability. The filament strain sensor is fabricated by the extrusion of poly(styrene-b-ethylene-b-butylene-b-styrene) (SEBS) filament constructing dentate groove structure and the subsequent ultrasonic treatment decorating carbon nanotubes (CNTs) on the surface of the SEBS filament. It is interesting to find that the strain sensing range of rough SEBS/CNTs filaments with dentate groove structure is wider than that of smooth filaments. More importantly, the rough filament strain sensors exhibit significantly enhanced recoverability without shoulder peak during the releasing process while the rough dentate groove structure has minor effects on the mechanical properties of SEBS filaments. The great improvement is ascribed to the uniform distribution of deformation because of the dentate groove structure, which induces reduction of the mechanical hysteresis effect and thereby decreases residual strain. Moreover, the rough filament strain sensors have a favorable integration of good stability, fast response time of 300 ms (0.5% strain is applied with a high strain rate of 500 mm/min) and excellent durability (1976 cycles at the strain of 50%). The rough filament strain sensors can accurately and stably monitor both large and subtle human motions (such as body motion, expression and phonation), showing broad application prospects in wearable devices.

Detonation performance of nitroaromatic decorated carbon nanotubes

In this study, density functional theory (DFT) was employed to predict thermochemical and energetic properties for single-walled carbon nanotubes (SWCNTs) decorated with one and more nitroaromatic substituents. Heat of sublimation and crystal density of these molecules were estimated on the basis of molecular surface properties calculated by electrostatic potential (ESP) analysis. Heats of formation in gas and solid phases were calculated using isodesmic approach. These data were used to measure velocity, pressure, and heat of detonation based on valid theoretical equations. Results show that crystal density of these molecules is close to TNT and their heat of formation is much larger. The calculated velocity and pressure of detonation for these molecules are approximately 4–6 km/s and 20–123 kbar, respectively; which are in the range of high explosives. However, their performance is lower than TNT. The detonation performance of these molecules increases as the number of nitroaromatic substituents increases.

Iron nanoparticle surface treatment of carbon nanotubes to increase fatigue strength of steel composites

A simple, scalable, and reproducible method is used to decorate carbon nanotubes (CNTs) with metal nanoparticles (NPs). Decorating CNTs with iron NPs prior to forming steel-based metal matrix composites (MMCs) improves the high-cycle fatigue (HCF) strength of the MMC by more than 350% vs. plain 1084 steel and more than 100% vs. an MMC with untreated CNTs. An inverse correlation between CNT loading and tensile strength was observed. The CNT surface treatment uses an organic microenvironment surrounding suspended CNTs and emulsion chemistry to treat individual CNTs or small bundles. This process can be adapted to work with other metal NPs or CNT types. This work demonstrates the potential for metal-treated CNTs to further improve the HCF strength of MMCs and paves a pathway toward additional CNT-reinforced composites.

Electrochemical two-electron O2 reduction reaction toward H2O2 production: using cobalt porphyrin decorated carbon nanotubes as a nanohybrid catalyst

A Co-tetramethoxyphenylporphyrin/carbon nanotube hybrid efficiently electrocatalyzes H2O2 production via 2e− O2 reduction with an ultrahigh mass activity. The catalytic mechanism is revealed by in situ infrared spectroscopy and DFT calculations.

Synthesis of Ag Nanoparticles Decorated Carbon Nanotubes as an Electrochemical Sensor for Determination of Phenolic Compounds in Shale Gas Wastewater

Synthesis of Ag Nanoparticles Decorated Carbon Nanotubes as an Electrochemical Sensor for Determination of Phenolic Compounds in Shale Gas Wastewater

Tuning the structure and morphology of Li2O2 by controlling the crystallinity of catalysts for Li-O2 batteries

Large overpotential in oxygen reduction and evolution reactions is the intractable obstruction of Li-O2 batteries, causing inferior round-trip efficiency and diminished cycle life. Modulating the reaction mechanism of Li2O2 is of crucial importance for a high-performance Li-O2 battery. Herein, we report a composite of amorphous RuO2 nanoparticles decorated carbon nanotubes (A-RuO2@CNT) as an efficient catalyst for Li-O2 batteries. The amorphous catalyst contains abundant defects and vacancies as well as distorted atom arrangements, which provide sufficient active sites for reactions and enhance the affinity for LiO2 intermediates. As a result, the formation/decomposition mechanisms of Li2O2 are reasonably regulated. An amorphous film-like Li2O2 product forms and uniformly deposits on the surface of A-RuO2@CNT, thus achieving faster redox kinetics and smaller overpotential. When used in Li-O2 batteries, the amorphous catalyst affords remarkably decreased charge overpotential and enhanced cyclic stability, which is superior to its crystalline counterpart.

Pt nanoparticle decorated carbon nanotubes nanocomposite based sensing platform for the monitoring of cell-secreted dopamine

Development of reliable sensors for real-time quantification of dopamine is highly essential to understand various biological processes and still remains challenge. Here, we proposed a novel and ultrasensitive electrochemical sensing platform for the monitoring of cell-secreted dopamine based on Pt nanoparticles (PtNPs) decorated multi-wall carbon nanotubes (MWCNTs) nanocomposite, which is synthesized by in-situ reduction of platinum on poly (diallyldimethylammonium chloride) (PDDA) functionalized MWCNTs. The unique structure of the hybrid nanocomposite and the interconnectivity between PtNPs and carbon nanotubes endow the nanocomposite with the enhancing conductivity and electrochemical activity. The Pt-MWCNTs hybrid modified screen-printed electrode exhibited excellent electrocatalytic ability for the detection of dopamine with a wide linear range (5 nM to 1 μM) and a low detection limit (2 nM). The developed sensor enables the real-time recording of dopamine released from PC12 cells induced by the stimulation of K+ saline. Also, this approach can be used to quantitatively evaluate the effects of antipsychotic drug (aripiprazole) on the dopamine release from cells treated with high K+. Results indicated that the sensor could provide an effective tool for the monitoring of extracellular neurotransmitters related to the exogenous agent and drug on the nervous system.

Synthesis and characterization of multi-walled carbon nanotubes decorated with hydroxyapatite

In this paper, multi-walled carbon nanotubes have been prepared at low synthesis temperatures and without high pressure by a simple chemical route. Fourier transformed infrared spectroscopy, Raman spectroscopy and X-ray diffraction analysis was used to determine the purity of the synthetized compound. Also, by transmission electron microscopy and atomic force microscopy, a diameter between 9 nm and 43 nm and approximately 500–600 nm in length of multi-walled carbon nanotubes, was confirmed. Further, the multi-walled carbon nanotubes functionalized with negative charged functional groups (anionic groups) were decorated with hydroxyapatite by co-precipitation method. The decoration of multi-walled carbon nanotubes with hydroxyapatite was confirmed by transmission electron microscopy, Fourier transformed infrared spectroscopy and X-ray diffraction analysis. Also, energy-dispersive X-ray analysis proved the successfully obtaining of the nanocomposites. The simple method presented here may be extended to synthesize other composites based on coated multi-walled carbon nanotubes.

Gold nanoparticle decorated carbon nanotube nanocomposite for dye-sensitized solar cell performance and stability enhancement

• AuNP/MWCNT inlaid mesoporous TiO 2 films are fabricated as photoanodes for DSSCs. • An enhancement of ~31% in PCE is achieved by using AuNP/MWCNT nanocomposite. • AuNP/MWCNT increases the PCE of the DSSC with a thin anode. • The developed nanocomposite is able to significantly improve the long-term stability of DSSCs. Improving the conversion efficiency of dye-sensitized solar cells (DSSCs) requires enhancing the photogeneration of charge carriers as well as facilitating their transport to electrodes before charge recombination or quenching can occur. Here we describe a simple, fast and large-area scalable procedure for the preparation of a nanocomposite made of functional gold nanoparticles (AuNPs) and multiwall carbon nanotubes (MWCNTs) to improve the performance of DSSCs. We fabricated AuNP/MWCNT inlaid mesoporous TiO 2 films as photoanodes in DSSCs, to improve crucial factors including light absorption, charge-carrier generation, collection and transport. By using a AuNP/MWCNT nanocomposite directly inlaid in TiO 2 as the working electrode, a power conversion efficiency (PCE) of 6.61% and short-circuit photocurrent density ( J sc ) of 12.26 mA cm −2 were obtained, representing an enhancement of ~31% in PCE and ~19% in J sc compared to a control cell based on TiO 2 alone. In addition, DSSCs based on the TiO 2 /AuNP/MWCNT photoanode remained remarkably stable compared with the control device, retaining 92% of the initial PCE value after ten days of continuous illumination.

Enhancement of Electron Emission Properties of Carbon Nanotubes by the Decoration with Low Work Function Metal Oxide Nanoparticles.

In the present report, the properties of the field emission devices of carbon nanotubes (CNTs) were remarkably improved by decorating their surface with magnesium oxide nanoparticles (MgO NPs). The MgO NPs were attached effectively on the surface of CNTs via thermal evaporation. The Raman spectra confirm the graphitic order of as-grown pristine CNTs with RBM (radial breathing mode), D band and G band peaks at the 282 cm-1, 1347 cm-1 and 1594 cm-1 respectively. The peak at 471 cm-1 indicates successful attachment of MgO NPs to the CNTs. The enhanced field emission properties of CNTs were mainly attributed to the MgO NPs which increased the field enhancement factor and the density of emission sites. The decreased work function and increased field enhancement factor were responsible for the improved FE properties of the CNTs. Our results indicate that the MgO decorated CNTs can be used as an effective field emitter for various electron emission devices. The turn-on field decrease from 1.6 V/μm to 1.3 V/μm and the maximum current density increases from 1.581 to 3.678 mA/cm2 after the decoration of CNTs with MgO NPs. The value of field enhancement factor (β) also increases from 2.814×10³ to 9.823×10³.

Synergistic Effect of Plasmonic Gold Nanoparticles Decorated Carbon Nanotubes in Quantum Dots/TiO2 for Optoelectronic Devices.

Here, a facile approach to enhance the performance of solar‐driven photoelectrochemical (PEC) water splitting is described by means of the synergistic effects of a hybrid network of plasmonic Au nanoparticles (NPs) decorated on multiwalled carbon nanotubes (CNTs). The device based on TiO2–Au:CNTs hybrid network sensitized with colloidal CdSe/(CdSexS1− x)5/(CdS)1 core/alloyed shell quantum dots (QDs) yields a saturated photocurrent density of 16.10 ± 0.10 mA cm−2 [at 1.0 V vs reversible hydrogen electrode (RHE)] under 1 sun illumination (AM 1.5G, 100 mW cm−2), which is ≈26% higher than the control device. The in‐depth mechanism behind this significant improvement is revealed through a combined experimental and theoretical analysis for QDs/TiO2–Au:CNTs hybrid network and demonstrates the multifaceted impact of plasmonic Au NPs and CNTs: i) hot‐electron injection from Au NPs into CNTs and TiO2; ii) near‐field enhancement of the QDs absorption and carrier generation/separation processes by the plasmonic Au NPs; iii) enhanced photoinjected electron transport due to the highly directional pathways offered by CNTs. These results provide fundamental insights on the properties of QDs/TiO2–Au:CNTs hybrid network, and highlights the possibility to improve the performance of other solar technologies.

A density functional theory study on the interaction of toluene with transition metal decorated carbon nanotubes: a promising platform for early detection of lung cancer from human breath

In this study, single-wall carbon nanotubes (SWCNTs) decorated by platinum-group transition metals (Pt, Pd, Rh, or Ru) were introduced as promising nanosensors for the detection of toluene, an important biomarker in the exhaled breath of the lung cancer patients. First-principle calculations based on density functional theory (DFT) was employed to scrutinize the impact of an individual toluene gas molecule on the structural, electronic, and magnetic properties of pristine and metal decorated SWCNTs. It was discovered that toluene is physisorbed on the pristine SWCNT through the interaction of the π orbitals of the carbon atoms in the toluene and the nanotube. Decoration of the SWCNT with metal atoms enhanced the adsorption energies significantly by means of strong overlapping between d orbital of the metal atoms and p orbital of C atoms in the benzene ring of toluene. Investigations showed that toluene is strongly chemisorbed on Rh- and Ru-SWCNT systems via strong covalent bonds with the superior response (−96.98% and −99.98%, respectively), and moderately chemisorbed on Pt-SWCNTs (−27.3%) and Pd-SWCNTs (61.60%). Our findings propose metal decorated SWCNT molecular sensors are attractive candidates for the detection of toluene and other lung cancer biomarkers in the exhaled breath of the lung cancer patients.

Synthesis of Au Nanoparticles Decorated Carbon Nanotubes as an Electrochemical Sensor for Phenol Determination in Petrochemical Wastewater

Synthesis of Au Nanoparticles Decorated Carbon Nanotubes as an Electrochemical Sensor for Phenol Determination in Petrochemical Wastewater