Multi-walled Carbon Nanotube Composite Films Research Articles

Influence of functional group on the electrical transport properties of polyvinyl alcohol grafted multiwall carbon nanotube composite thick film

We present a novel technique to obtain a higher or lower value of dielectric constant due to the variation of a functional group on the surface of multiwall carbon nanotube (MWCNTs) for a polyvinyl alcohol (PVA) grafted MWCNT system. We have prepared PVA grafted pristine and different types of functionalized (-COOH, -OH, and -NH2) MWCNT nanocomposite films. The strong interfacial interaction between the host PVA matrix and nanofiller is characterized by different experimental techniques. The frequency variation of the electrical transport properties of the composite films is investigated in a wide temperature range (303 ≤ T ≤ 413 K) and frequency range (20 Hz ≤ f ≤ 1 MHz). The dielectric constant of the amine (-NH2) functionalized MWCNT incorporated PVA film is about 2 times higher than that of the pristine MWCNT embedded PVA film. The temperature variation of the dielectric constant shows an anomalous behaviour. The modified Cole-Cole equation simulated the experimentally observed dielectric spectroscopy at high temperature. The ac conductivity of the composite films obeys the correlated barrier hopping model. The imaginary part of the electric modulus study shows the ideal Debye-type behaviour at low frequency and deviation of that at high frequency. To illustrate the impedance spectroscopy of the nanocomposite films, we have proposed an impedance based battery equivalent circuit model. The current-voltage characteristic shows hysteresis behaviour of the nanocomposite films. The trap state height for all composite films is evaluated by simulating the current density-electric field data with the Poole-Frenkel emission model. This investigation opens a new avenue for designing electronic devices with a suitable combination of cost effective soft materials.

Electrolytic Synthesis of Ni-W-MWCNT Composite Coating for Alkaline Hydrogen Evolution Reaction

Nickel–tungsten multi-walled carbon nanotube (Ni-W-MWCNT) composite films were fabricated by an electrodeposition technique, and their electrocatalytic activity toward hydrogen evolution reaction (HER) was studied. Ni-W-MWCNT composite films with a homogeneous dispersion of MWCNTs were deposited from an optimal Ni-W plating bath containing functionalized MWCNTs, under galvanostatic condition. The presence of functionalized MWCNT was found to enhance the induced codeposition of the reluctant metal W and resulted in a W-rich composite coating with improved properties. The electrocatalytic behaviors of Ni-W-MWCNT composite coating toward HER were studied by cyclic voltammetry (CV) and chronopotentiometry techniques in 1.0 M KOH medium. Further, Tafel polarization and electrochemical impedance spectroscopy (EIS) studies were carried out to establish the kinetics of HER on the alloy and composite electrodes. The experimental results revealed that the addition of MWCNTs (having a diameter of around 10-15 nm) into the alloy plating bath has a significant effect on the electrocatalytic behavior of Ni-W alloy deposit. The Ni-W-MWCNT composite coating was found to show better HER activity than the conventional Ni-W alloy coating. The enhanced electrocatalytic activity of Ni-W-MWCNT composite coating is attributed to the MWCNT intersticed in the deposit matrix, evidenced by surface morphology, composition and phase structure of the coating through SEM, EDS and XRD analyses, respectively.

Strain-gauge sensoring composite films with self-restoring water-repellent properties for monitoring human movements

Abstract Flexible strain-gauge sensors are an essential constituent in smart electronic devices that can monitor the complex movements of people. We herein report a strain-gauge sensor with self-restoring water repellency, based on thermoplastic polyurethane (TPU)/multi-walled carbon nanotube composite films . TPU/carbon nanotube (CNT) composite films were simply fabricated by the filtration of CNT suspensions using electrospun TPU nonwovens as the filter paper. The strain-gauge sensors exhibited not only high sensitivity and durability, but also excellent self-restoring water repellency. The sensors performed well in monitoring a person’s fingers, elbows, knees, and even neck movements. The self-restoring water repellency of the strain-gauge sensors originated from the hierarchical CNT networks on the TPU nonwovens. The “mesh-like” CNT networks would be cracked or broke under mechanical deformation , exposing the “feather-duster” structures underneath. The integrated hierarchical roughness mobilized the water droplets on the surface even under mechanical deformation. It is expected that the strain-gauge sensors will be applied in wearable electronic devices with super water-repellent properties. The work paves the possibility to fabricate high performance strain-gauge sensors that could be used in raining days or moist conditions.

Fabrication of surface-modified poly(3-aminobenzoic acid)/multiwalled carbon nanotubes composite thin films for hydrogen peroxide sensing

ABSTRACTThis work reports the fabrication of poly(3-aminobenzoic acid), (PABA)/multiwalled carbon nanotubes (MWNTs) composite thin film modified with layer-by-layer (LbL) self-assembled multilayers of cytochrome C (Cyt C) and poly(diallyldimethylammonium chloride) (PDADMAC) for hydrogen peroxide (H2O2) sensing on indium tin oxide-coated glass substrate. An electropolymerized PABA/MWNTs composite thin film was employed for the covalent attachment of Cyt C. The subsequent multilayers of PDADMAC and Cyt C were then fabricated using LbL deposition technique. The fabricated film was characterized by UV-vis spectroscopy, Raman spectroscopy, SEM and AFM. The modified thin film was finally used for successive detection of H2O2 at constant applied potential through an electrochemical method.

Preparation of ZnO nanoribbon–MWCNT composite film and its application as antimicrobial bandage, antibacterial filter and thermal IR camouflage material

A zinc oxide nanoribbon (ZnO NR)–multiwall carbon nanotube (MWCNT) composite film was prepared by filtration technique. The film was characterized by X-ray diffraction spectroscopy, scanning electron microscopy (SEM), Raman spectroscopy, infrared (IR) spectroscopy and reflectance spectroscopy. The SEM images showed ZnO NRs trapped in the porous MWCNT network. This composite film displayed a strong antimicrobial property and porous structure, which has potential application as an antimicrobial bandage material. The composite film successfully removed the Escherichia coli bacteria from water and destroyed the bacteria retained on its surface due to the antibacterial action of ZnO NRs. The absorption of thermal IR radiation by the composite film was studied by thermography, which can be useful in IR camouflage applications.

Electrochemical Determination of Bisphenol A on a Glassy Carbon Electrode Modified with Gold Nanoparticles Loaded on Reduced Graphene Oxide-multi Walled Carbon Nanotubes Composite

Abstract A glassy carbon electrode (GCE) modified with gold nanoparticles loading on the reduced graphene oxide (rGO)-multi-walled carbon nanotubes (MWCNTs) composite film was fabricated by a two-step procedure. Firstly, rGO-MWCNTs composite were prepared by in-situ chemical reduction with hydrazine as a reducing agent. Then, gold nanoparticles (AuNPs) were deposited on the surface of rGO-MWCNTs using simple cyclic voltammetry. This modified electrode was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and electrochemical methods. Furthermore, the electrochemical behavior of bisphenol A (BPA) was also investigated using this modified electrode. The results showed that the modified electrode had high electrochemical activity for the oxidation of BPA. In 0.10 M phosphate buffer (PBS, pH 7.0), the linear range for the determination of BPA with differential pulse voltammetry (DPV) was in the range of 5.0 × 10−9−1.0 × 10−7 M and 1.0 × 10−7−2.0 × 10−5 M. The detection limit was 1.0 × 10−9 M (S/N = 3). The as-prepared modified electrode was successfully used to determine BPA in river water and the shopping receipt samples with recoveries range of 97%–110% and 98%–104%, respectively.

Electropolymerized polyaniline/graphene nanoplatelet/multi-walled carbon nanotube composites as counter electrodes for high performance dye-sensitized solar cells

Polyaniline (PANI)/graphene nanoplatelet (GNP)/multi-walled carbon nanotube (MWCNT) composite films deposited on fluorine-doped tin oxide (FTO) substrates were successfully fabricated through electrochemical method without pre-treatment of GNP and MWCNT to provide a lower cost counter electrode (CE) for dye-sensitized solar cells (DSSCs). By varying the contents of GNP and MWCNT in the PANI composite CE, the short-circuit current density of DSSC was found to linearly relate to the reduction current density of I−/I3− redox couples measured by cyclic voltammetry. The open-circuit voltage (VOC) is also highly dependent on the reduction potential of redox couples. Besides, the charge transfer resistance at the electrolyte/CE interface measured by electrochemical impedance spectroscopy has an approximately linear relationship with the sheet resistance of PANI composite CE. Notably, the DSSC with the CE fabricated by the weight ratio of PANI/GNP/MWCNT at 1:0.003:0.0045 yielded the highest power conversion efficiency of 7.67±0.05%, which is comparable with the conventional Pt cell (7.62±0.07%).

Electropolymerization of β-cyclodextrin onto multi-walled carbon nanotube composite films for enhanced selective detection of uric acid

An amperometric uric acid (UA) sensor incorporating a multi-walled carbon nanotubes (MWCNT) network in Nafion and electropolymerized β-cyclodextrin (β-CD) layer is investigated. The electrochemical sensor is comprised of a glassy carbon electrode modified with Nafion-MWCNT nanocomposite film, a β-CD polymer inner selective layer, and a Hydrothane polyurethane (HPU) outer selective coating. The surface morphology and electronic structure of the electrode material are characterized using transmission electron microscopy (TEM), scanning electron microscope (SEM), and Fourier transform infrared (FTIR) spectroscopy. The electrocatalytic activity of the sensor is studied using cyclic voltammetry (CV), chronocoulometry (CC) and differential pulse voltammetry (DPV). Analytical performance of the electrochemical sensor scheme with and without MWCNT and/or β-CD polymer is determined from direct UA injection during an amperometric analysis. The effective surface area is notably higher for Nafion-MWCNT coated glassy carbon electrodes, which in turn enhanced the sensitivity when coated with β-CD polymer. The results indicated an excellent electrocatalytic property of Nafion-MWCNT/β-CD film for UA detection with enhanced sensitivity (2.11μA·mM−1), wide linear responses over physiologically relevant concentrations, and fast response times. Enhancement is attributed to MWCNT offering increased electroactive surface area and the ability of β-CD to selectively sequester UA.

Synthesis and characterization of phenylethynyl-terminated polyimide/carboxylated multiwalled carbon nanotube composite film

Phenylethynyl-terminated polyimide (PI)/carboxylated multiwalled carbon nanotube (MWCNT) composite films were synthesized from 4,4′-oxydianiline, carboxylated MWCNTs, and 3,3′,4,4′-biphenyl tetracarboxylic dianhydride and capped by 4-phenylethynylphthalic anhydride through in situ polymerization under sonication. The results of scanning electron microscopy indicated that the carboxylated MWCNTs were uniformly dispersed in the phenylethynyl-terminated PI matrix. Thermal gravimetric analysis indicated that the initial thermal decomposition temperatures of the films were up to 500°C, and the addition of carboxylic MWCNT have advantage of thermal properties of the phenylethynyl-terminated PI. The dynamic mechanical thermal analysis results clearly indicated that the glass transition temperature increases with increasing carboxylated MWCNT content. In addition, the mechanical properties of the composite films were improved by the carboxylated MWCNTs. The electrical properties were greatly enhanced due to the good conductivity of the carboxylated MWCNTs.

Enhanced Electrochemical Performance Of Xanthine Biosensor By Core - Shell Magnetic Nanoparticles And Carbon Nanotube Interface

Xanthine oxidase (XOD) was extracted from bovine milk. Immobilization of extracted XOD was performed by covalently Nethyl-N'-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxy succinimide (NHS) chemistry on core–shell magnetic nanoparticles (MNPs)/carboxylated multiwalled carbon nanotube (c-MWCNT) composite film. The film was electrodeposited on glass plate electrode (usually the surface of fluorine doped tin oxide (FTO). In order to characterize nanocomposite modified FTO electrode, various methods including scanning electron microscopy (SEM), cyclic voltammetry (CV), Fourier transform infrared (FTIR), and electrochemical impedance spectroscopy (EIS) were performed. These methods were evaluated prior and following XOD immobilization. The working optimal conditions for instance 30 °C, +0.2 V vs. Ag/AgCl, sodium phosphate buffer at pH 7.0 were attributed for developing this biosensor. The linearity of the response upto 150 μM xanthine concentration, 0.05 μM (S/N = 3) detection limit and a response time within 3 s were obtained. The biosensor was stored at 4 °C and used above 100 times for a long period of 120 days. The loss of 50 % of activity was noticed. This fabricated biosensor was then employed determining xanthine in fish meat sample. Copyright © 2016 VBRI Press.

Enhancement of the ferroelectricity of poly(vinylidene fluoride)/multiwalled carbon nanotube composite scaffolds and its effect on the cellular metabolic activity

Abstract The highly polar surfaces having a strong effect on the cellular growth are desirable for the preparation of effective scaffolds. Here, we demonstrate that poly(vinylidene fluoride) (PVDF)/multiwalled carbon nanotube (MWCNT) composite films having a very high β-phase that shows the ferroelectric properties are quite effective for cell growth of RT4-D6P2T cells (Schwannoma cell line of rats), U87-MG (glioblastoma cell line of human) and SH-SY5Y (neuroblastoma cell line of human) cells. The contents of polar β-phase in the nanocomposite films could be finely tuned by the variation of MWCNT amount. The cell growth behavior of the three types of cells was congruent with the amount of the polar β-phase. Addition of 0.5 wt% MWCNT could generate 10% more β-phase in the composite, but show 250% more cell proliferation rates for all three cells than neat PVDF film after 7days of incubation. In vitro tests revealed synergy effects of scaffold’s stiffness and ferroelectricity on the cellular activity with the amount of MWCNT in the composite film.

Hydrophilic Modification of Multi-Walled Carbon Nanotube for Building Photonic Crystals with Enhanced Color Visibility and Mechanical Strength.

Low color visibility and poor mechanical strength of polystyrene (PS) photonic crystal films have been the main shortcomings for the potential applications in paints or displays. This paper presents a simple method to fabricate PS/MWCNTs (multi-walled carbon nanotubes) composite photonic crystal films with enhanced color visibility and mechanical strength. First, MWCNTs was modified through radical addition reaction by aniline 2,5-double sulfonic acid diazonium salt to generate hydrophilic surface and good water dispersity. Then the MWCNTs dispersion was blended with PS emulsion to form homogeneous PS/MWCNTs emulsion mixtures and fabricate composite films through thermal-assisted method. The obtained films exhibit high color visibility under natural light and improved mechanical strength owing to the light-adsorption property and crosslinking effect of MWCNTs. The utilization of MWCNTs in improving the properties of photonic crystals is significant for various applications, such as in paints and displays.

Structure evolution in poly(ethylene terephthalate) (PET) – Multi-walled carbon nanotube (MWCNT) composite films during in-situ uniaxial deformation

Combined small- and wide-angle X-ray scattering (SAXS/WAXS), mechanical and thermal techniques have been used to follow the morphology evolution in a series of poly(ethylene terephthalate) (PET) multiwall carbon nanotube (MWCNT) composite films during quasi solid-state uniaxial deformation at low strain rates. Uniaxially deformed PET-MWCNT films displayed improved mechanical properties compared with unfilled PET films. SAXS/WAXS data revealed a well oriented lamellar structure for unfilled PET films. In contrast, the PET-MWCNT composites revealed a nanohybrid shish-kebab (NHSK) morphology, with reduced orientation and crystallinity. Mechanistically, this morphology development is attributed to the MWCNTs acting as shish for the epitaxial growth of PET crystallites. Furthermore, nucleation and crystal growth occurs in the PET matrix, but MWCNTs ultimately inhibit crystallite development and hinder a final lamellar structure developing. The results show unequivocally the role MWCNTs play as nanofillers, in the morphology development, thermal and mechanical properties in composite polymer films.

Dielectric behavior of a flexible three-phase polyimide/BaTiO3/multi-walled carbon nanotube composite film

A three-phase composite film was produced by inserting multi-walled carbon nanotubes (MWCNTs) and BaTiO3 nanoparticles into polyimide (PI). The combination of in-situ polymerization and water-based preparation involved in the experiment ensured fillers’ homogeneous dispersion in the matrix, which led to flexible shape of the composite films. The dielectric properties of composite films as a function of the frequency and the volume fraction of MWCNTs were studied. Such composite film displayed a high dielectric constant (314.07), low dielectric loss and excellent flexibility at 100[Formula: see text]Hz in the neighborhood of percolation threshold (9.02 vol%) owing to the special microcapacitor structure. The experimental results were highly consistent with the power law of percolation theory.

Magnetic studies of polystyrene/iron-filled multi-wall carbon nanotube composite films

Polystyrene/iron-filled multi-wall carbon nanotube composite films were prepared by solution processing, forge-rolling and stretching methods. Elongated iron carbide nanoparticles formed because of catalytic growth are situated inside the hollow cavity of the nanotubes. Magnetic susceptibility measurements as well as records of isothermal hysteresis loops performed in three perpendicular directions of magnetic field confirmed that the nanotubes have a preferential alignment in the matrix. Strong diamagnetic anisotropy in the composites emerges not only from the MWCNTs but also from the polystyrene matrix. The polymer sticks to the honeycomb lattice through the interaction of the π-orbitals of the phenyl ring and those of the carbon nanotube, contributing to anisotropic diamagnetic response. The contribution of iron nanoparticles to overall magnetic response strongly depends on nanotube concentration in the composite as well as on matrix-filler non-covalent stacking, which influences magnetic interparticle interactions.

Electrocatalytic oxidation of small organic molecules on Pt-Au nanoparticles supported by POMAN-MWCNTs

Poly (o-methoxyaniline) and multi-wall carbon nanotube composite (POMAN-MWCNT) films were deposited onto the platinum (Pt) electrode surface by cyclic voltammetry (CV). Then, platinum and gold (Au) nano-particles were deposited by CV and the double potential deposition method to modify the composite film on the Pt electrode. The morphology of the composite film was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and its electrocatalytic activity toward methanol and formaldehyde oxidation was studied by CV and other electrochemical methods. The results demonstrated that Pt-Au/POMAN-MWCNTs obtained by the double potential deposition method had a much higher catalytic activity and better anti-poisoning property for electrooxidation of methanol and formaldehyde. The improved catalytic performance could be attributed to the uniformly distribution of duel-metal nanoparticles and the synergistic effect between Pt and Au metals. The abstract should briefly state the problem or purpose of the research, indicate the methodology used, summarize the principal findings and major conclusions.

Fabrication and Characterization of Pyrrole/Multi-Walled Carbon Nanotubes Composite Electrodes

Carbon based nano-materials have received a large amount of focus because of their ultra-high energy density which approaches 600 F/g. Specifically, pyrrole and graphene double layer supercapacitors have achieved the highest charge density. Their performance has been attributed to the films conductivity, surface area and low density. This study focused on fabrication of a pyrrole (Pyr)/ multi-walled carbon nanotubes (MWCNTs) composite for analysis. Composite films were electrochemically deposited from an aqueous MWCNTs, Pyr, and sodium dodecyl sulfate (SDS) solution onto a copper substrate. After deposition the films were annealed at 230˚C for an hour, allowed to cool to room temperature, then exfoliated using tape. SEM, AFM, and ATR-FT-IR spectroscopy were performed on unexfoliated films. 4-point probe conductivity and UV-Vis transmission measurements were performed on exfoliated films. SEM analysis (Figure 1) shows two components of the composite, MWCNTs and Pyr forming a dense mat. All three components of the precursor were present in the final film as confirmed by ATR-FT-IR spectroscopy and the films were minimally transparent in the UV-Vis region (%T<.5%). The roughness of the film from AFM was RMS = 77.1 nm. Lastly the films had low conductivity of 0.015 S/cm. Further optimization of the precursor and deposition cycle will hopefully result in composite films with high charge density for applications in double layered capacitors. Figure 1 Figure 1:SEM micrograph of the edge of the Pyr/ MWCNT composite film deposition.

Electrochemical Performance of Multi Walled Carbon Nanotube and Graphene Composite Films Using Electrophoretic Deposition Technique

This study aims to investigate multi-walled carbon nanotube and graphene composite thin films fabricated using cathodic electrophoretic deposition in aqueous solution. The deposition mechanism and films microstructure were investigated using the cyclic voltammetry (CV) and field emission scanning electron microscope. The depositions yield varied by the deposition time and deposition voltage. The composite films were studied for its application in the electrochemical capacitor. The electrochemical performance showed the capacitive behavior of the films in 6 M potassium hydroxide electrolyte. CV scans were verified from 0 to 1 V at different scan rates. The specific capacitance of 29 Fg-1 was achieved at the scan rate of 1 mVs-1.

Preparation and characterization of sulfonated poly(1,3,4-oxadiazole)/multi-walled carbon nanotube composite films with high performance in electric heating and thermal stability

For manufacturing thermally stable electric heating composite films, a sulfonated poly(1,3,4-oxadiazole) (sPOD) was synthesized and it was composited with pristine MWCNT of 0.1–10.0 wt% by an ultrasonicated solution mixing and casting. SEM images revealed that the pristine MWCNTs were dispersed well in the composite matrix via π–π interaction between the MWCNTs and the aromatic rings of sPOD backbone. The electrical resistivity of the composite films decreased considerably from ∼109 Ω cm to ∼100 Ω cm with the increment of the MWCNT content by forming a percolation threshold at ∼0.026 wt%. The composite films with 5.0–10.0 wt% MWCNT contents, which had sufficiently low electrical resistivity of ∼103–100 Ω cm, exhibited excellent electric heating performance by attaining high maximum temperatures as well as electric energy efficiency. Since the dominant thermal decomposition of the composite films took place at ∼500 °C, sPOD/MWCNT composite films with low electrical resistivity could be used for high performance electric heating materials for advanced applications.

A novel sensor based on Fe3O4 nanoparticles–multiwalled carbon nanotubes composite film for determination of nitrite

A novel nitrite sensor was constructed via electropolymerization of l-cysteine on the multiwalled carbon nanotubes and then immobilization of cationic poly(diallyldimethylammonium chloride) coated Fe3O4 nanoparticles through electrostatic interaction at glassy carbon matrix. Under the optimized conditions, the obtained sensor exhibited good electrocatalytic activity for the oxidation of nitrite, and the peak current of nitrite increased linearly with its concentration from 7.49×10−6 to 3.33×10−3mol/L (R=0.9998) with the detection limit of 8.46×10−7mol/L (S/N=3). Moreover, the sensor exhibited good sensitivity, stability and repeatability with potential applications.