Multiwalled Carbon Nanotubes Nanocomposite Film Research Articles

Preparation of ZnS-decorated MWCNTs/p-Si hybrid photodetector by pulsed laser deposition

In the present work, a zinc sulfide (ZnS) nanostructure film is deposited on multi-walled carbon nanotubes (MWCNTs) by means of pulsed laser deposition technique. The structural, morphological, and optical properties of ZnS-decorated MWCNTs are investigated. X-ray diffraction (XRD) studies showed the presence of peaks related to polycrystalline faced-center cubic ZnS and MWCNTs. The best crystallinity is found for ZnS/MWCNTs nanocomposite prepared at 5.3 J/cm2. Scanning electron microscope (SEM) investigation shows that the deposited ZnS films have a smooth structure with some spherical particles attached to the film surface. The SEM image of the ZnS-decorated MWCNTs confirms the formation of a nanocomposite morphology structure. The optical energy gap of ZnS film decreases from 4 to 3.85 eV as laser fluence increases from 5.3 to 6.5 J/cm2, and in addition, the energy gap of ZnS-decorated MWCNTs nanocomposite film is smaller than that of ZnS film. The current-voltage characteristics of ZnS/Si and ZnS-decorated MWCNTs/Si heterojunction photodetectors are measured in dark and illumination conditions. The responsivity of n-ZnS/p-Si and n-ZnS/MWCNTs/p-Si prepared at 6.5 J/cm2 was found to be as high as 0.35 at 710 nm and 0.674 A/W at 610 nm, respectively. The figures of merit of the ZnS/Si photodetectors, including external quantum efficiency and specific detectivity, were improved after being embedded with MWCNTs. The band lineup of n-ZnS-decorated MWCNTs/p-Si under illumination was constructed.

Optical, optoelectronic, structural, and chemical characterizations of (PEO-PVA)/MWCNT nanocomposite films

Nanocomposite films were fabricated from polyethylene oxide (PEO) and polyvinyl alcohol (PVA) incorporated with variant contents of multi-walled carbon nanotubes (MWCNTs) deposited on the glass substrates. FTIR and XRD techniques determined the chemical and structural characteristics of (PEO-PVA)/MWCNTs nanocomposite films. The optical properties, including refractive index, extinction coefficient, and dielectric functions, were comprehended via UV-Vis spectroscopy's transmittance and reflectance spectra. Classical and quantum models, including Al-Bataineh, Urbach, Spitzer-Fan, and Drude models, are employed to determine optical and optoelectronic characteristics. The optical bandgap energy of the PEO-PVA film was found to be 4.032 eV. Introducing MWCNTs to PEO-PVA films leads to a decrease in bandgap energy. The effective medium models (EMMs) described the diluted MWCNTs in the host PEO-PVA matrix. Our samples obey the Maxwell-Garnett model indicating a considerable distance between the MWCNTs in the polymer matrix with predicted possible interactions between the nanotubes and the host polymer chain. In addition, electrical conductivity increased as increasing MWCNT in PEO-PVA films.

Synthesis and characterization of platinum multi-walled carbon nanotubes nanocomposite film electrode

Carbon nanotubes (CNTs) were synthesized by a bimetallic (Fe–Co/CaCO3) catalytic chemical vapour deposition (CCVD) method. The synthesized CNTs were purified with acid to remove the catalyst impurities to enhance the deposition of platinum (Pt) onto the CNTs surface. Platinum multiwall (Pt-MWCNTs) nanocomposites were produced by a wet impregnation technique dispersed in Texanol and Acrylic resins to form a paste. The paste was screen printed on an FTO glass substrate. Surface morphology, microstructure, chemical composition, crystallographic phase, surface area and electrical performance of the Pt-MWCNTs nanocomposites were measured by HRSEM, HRTEM, EDS, XPS and XRD. The electrical conductivity of the electrode produced was found to be 4.927 S m−1. The results showed that the prepared nanocomposites will be a good electrode material in solar cell applications.

Chitosan/MWCNTs composite as bone substitute: Physical, mechanical, bioactivity, and biodegradation evaluation

In the present research, via the solvent casting method, Chitosan(CS)/multiwalled carbon nanotubes (MWCNTs) nanocomposite films were prepared through the use of four different percentages (1, 1.5, 2, and 2.5 wt%) of CS as polymer matrix and two percentages (0.5 and 1 wt%) of MWCNTs as ceramic reinforcement. Based on the results of TGA, it was shown that the addition of MWCNTs augmented the thermal stability of CS film. The results of XRD showed that MWCNTs induced the crystallization of chitosan film and FTIR analysis demonstrated the formation of CS/MWCNTs composite film. According to the results of tensile tests, the highest strength belonged to 2.5 wt% CS/0.5 wt% MWCNTs nanocomposite film which was increased by 176% (from 18.26 to 50.46 MPa) in comparison to tensile strength of 2.5 wt% CS film and the Young's modulus of CS/MWCNTs film increased by 195% (from 406 to 1,197 MPa) in comparison to the Young's modulus of CS film. The best film with 2.5 wt% CS/0.5 wt % MWCNTs was selected as an optimum sample for other experiments. Contact angle analysis indicated that with the addition of MWCNTs, the contact angle of CS films decreased. The results of bioactivity test showed that adding 0.5 wt% MWCNTs to CS film improved the bioactivity of CS film. Based on the biodegradability evaluation, the addition of MWCNTs to CS film reduced the degradation rate of CS film. The research illustrated the potentials of CS/MWCNTs in bone substitute. POLYM. COMPOS., 40:E1622–E1632, 2019. © 2018 Society of Plastics Engineers

Preparation and Tribological Properties of Polyimide/Carboxyl-Functionalized Multi-walled Carbon Nanotube Nanocomposite Films Under Seawater Lubrication

The polyimide (PI)/carboxyl-functionalized multi-walled carbon nanotube (MWCNTs-COOH) nanocomposite films were synthesized by situ polymerization method. The results showed that the incorporation of MWCNTs-COOH greatly enhanced thermal stability and mechanical property of PI. PI/MWCNTs-COOH nanocomposites exhibited better tribological properties under seawater lubrication than other conditions because of excellent lubricating effect of seawater. Besides, the wear resistance of PI under seawater lubrication had been greatly improved by filling MWCNTs-COOH, because strong interfacial adhesion between PI matrix and MWCNTs-COOH nanofillers could transfer load effectively between contact surfaces. In particular, when the content of MWCNTs-COOH was 0.7 wt%, the corresponding PI/MWCNTs-COOH nanocomposites had the best tribological properties under seawater lubrication. The polyimide (PI)/carboxyl-functionalized multi-walled carbon nanotube (MWCNTs-COOH) nanocomposite films were synthesized by in situ polymerization using 4,4′-oxydianiline (ODA), carboxyl-functionalized multi-walled carbon nanotube (MWCNTs-COOH) and pyromellitic dianhydride (PMDA). The tribological properties of PI/MWCNTs-COOH nanocomposite films were measured under dry sliding condition, pure water condition and seawater lubrication condition. This study can provide some guidance to develop polymer materials with excellent wear resistance suitable for ocean environment.

A facile sensitivel-tyrosine electrochemical sensor based on a coupled CuO/Cu2O nanoparticles and multi-walled carbon nanotubes nanocomposite film

L-tyrosine in human urine is an essential biomarker for the early detection of various cancers. A facile electrochemical method for preparing a coupled copper oxide/cuprous oxide nanoparticles and multi-walled carbon nanotubes nanocomposite film modified glass carbon electrode (CuO/Cu2O/MWCNTs/GCE) via in situ growth is proposed for electrochemical sensing of L-tyrosine. The electrocatalytic activity of CuO/Cu2O/MWCNTs/GCE was investigated for L-tyrosine by cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA), and the morphology and shape of the nanocomposite film were characterized by scanning electron microscope (SEM), energy-dispersive spectroscopy (EDS), transmission electron microscope (TEM) and X-ray powder diffraction (XRD). An irreversible oxidation peak for L-tyrosine at a potential of 0.645 V (vs. SCE) was observed in pH 8.0 of phosphate buffer solution at the CuO/Cu2O/MWCNTs/GCE electrode. The as-fabricated L-tyrosine sensor shows a fast response time (less than 2 s), a wide linear range 2 × 10−7–2 × 10−4 M, a high sensitivity of 1001 μA mM−1 cm−2 and a low detection limit of 9.6 × 10−9 M (at signal/noise = 3) in pH 8.0 phosphate buffer solution at 0.645 V. The nanocomposite film electrode has been successfully applied to determine L-tyrosine in human urine. It exhibits high electrocatalytic activity, satisfactory repeatability, stability, fast response and good selectivity against potentially interfering species, which suggests its potential for the development of a sensitive, selective, easy-operation and low-cost L-tyrosine sensor for practical routine analyses. The proposed new facile electrochemical growth method has the potential to expand the range of nanocomposite materials applied for the detection of various electroactive substances.

Electrochemical sensor for determination of aflatoxin B1 based on multiwalled carbon nanotubes-supported Au/Pt bimetallic nanoparticles

A sensitive and selective imprinted electrochemical sensor for the determination of aflatoxin B1 (AFB1) was constructed on a glassy carbon electrode by stepwise modification of functional multiwalled carbon nanotubes (MCNTs), Au/Pt bimetallic nanoparticles (Au/PtNPs), and a thin imprinted film. The fabrication of a homogeneous porous poly o-phenylenediamine (POPD)-grafted Au/Pt bimetallic multiwalled carbon nanotubes nanocomposite film was conducted by controllable electrodepositing technology. The sensitivity of the sensor was improved greatly because of the nanocomposite functional layer; the proposed sensor exhibited excellent selectivity toward AFB1 owing to the porous molecular imprinted polymer (MIP) film. The surface morphologies of the modified electrodes were characterized using a scanning electron microscope. The performance of the imprinted sensor was investigated by cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy in detail. A linear relationship between the sensor response signal and the logarithm of AFB1 concentrations ranging from 1 × 10−10 to 1 × 10−5 mol L−1 was obtained with a detection limit of 0.03 nmol L−1. It was applied to detect AFB1 in hogwash oil successfully.

Electrochemical and Optical Investigation of Conductive Polymer and MWCNT Nanocomposite Film

Composites of multi-walled carbon nanotubes (MWCNT) and conductive polymer with good uniformity were prepared by electropolymerization. Molecular modeling calculations were carried out for electroactive monomer (OAP) polymerization with density functional theory (DFT) level using 6-311G(d,p) basis set for all atoms and Gaussian 03 program package. The reflectance and transmittance amplitudes of the composite were obtained, using the continuity of the tangential components of electrical and magnetic fields at interfaces and solving the algebraic matrix equation. The calculated absorbance spectra as a function of wavelength for MWCNTs dispersed in the conductive polymer are depicted. Band gap of the p-type semiconducting film was obtained from the plot of (αhv)2vs. photon energy.

Co-immobilization of glucose oxidase and xylose dehydrogenase displayed whole cell on multiwalled carbon nanotube nanocomposite films modified electrode for simultaneous voltammetric detection of d-glucose and d-xylose

In this paper, we first report the construction of Nafion/glucose oxidase (GOD)/xylose dehydrogenase displayed bacteria (XDH-bacteria)/multiwalled carbon nanotubes (MWNTs) modified electrode for simultaneous voltammetric determination of d-glucose and d-xylose. The optimal conditions for the immobilized enzymes were established. Both enzymes retained their good stability and activities. In the mixture solution of d-glucose and d-xylose containing coenzyme NAD+ (the oxidized form of nicotinamide adenine dinucleotide), the Nafion/GOD/XDH-bacteria/MWNTs modified electrode exhibited quasi-reversible oxidation-reduction peak at −0.5V (vs. saturated calomel electrode, SCE) originating from the catalytic oxidation of d-glucose, and oxidation peak at +0.55V(vs. SCE) responding to the oxidation of NADH (the reduced form of nicotinamide adenine dinucleotide) by the carbon nanotubes, where NADH is the resultant product of coenzyme NAD+ involved in the catalysis of d-xylose by XDH-displayed bacteria. For the proposed biosensor, cathodic peak current at −0.5V was linear with the concentration of d-glucose within the range of 0.25–6mM with a low detection limit of 0.1mM d-glucose (S/N=3), and the anodic peak current at +0.55V was linear with the concentration of d-xylose in the range of 0.25∼4mM with a low detection limit of 0.1mM d-xylose (S/N=3). Further, d-xylose and d-glucose did not interfere with each other. 300-fold excess saccharides including d-maltose, d-galactose, d-mannose, d-sucrose, d-fructose, d-cellobiose, and 60-fold excess l-arabinose, and common interfering substances (100-fold excess ascorbic acid, dopamine, uric acid) as well as 300-fold excess d-xylitol did not affect the detection of d-glucose and d-xylose (both 1mM). Therefore, the proposed biosensor is stable, specific, reproducible, simple, rapid and cost-effective, which holds great potential in real applications.

Acid yellow 9 as a dispersing agent for carbon nanotubes: Preparation of redox polymer–carbon nanotube composite film and its sensing application towards ascorbic acid and dopamine

In this study, we show that acid yellow 9 (4-amino-1-1′-azobenzene-3,4′-disulfonicacid, AY) is a good stabilizing agent for multi-walled carbon nanotubes (MWCNTs). MWCNTs dispersed in AY solution was remained stable about three months and even remained stable after centrifugation at 10,000 rpm for 30 min. Using MWCNTs/AY dispersion, thin-films were prepared on indium tin oxide coated glass electrode and glassy carbon electrodes. Further, dried films of MWCNTs/AY were subjected to electropolymerization in 0.1 M H 2SO 4 solution. Adsorbed AY molecules on MWCNTs get polymerized and they yield a polymer–MWCNTs nanocomposite film on electrode surface which is found to be electrochemically active in wide pH range (1–11). Characterization studies were performed using cyclic voltammetry and SEM. These studies are supported that hybrid material PAY/MWCNTs was obtained. Moreover, newly synthesized PAY–MWCNTs composite film showed excellent electrocatalytic activity towards oxidation of dopamine (DA) and ascorbic acid (AA) with high sensitivity in physiological pH. Linear sweep voltammetry was employed to the determination of DA in the presence of AA in the range of 2 × 10 −7 to 1.4 × 10 −6 M. Amperometry was employed to determination of AA at 0.0 V in the range from 1 × 10 −6 to 5.6 × 10 −5 M, and DA, uric acid are not interfered on the steady-state current of AA. In addition, real samples such as dopamine injection and AA spiked into human urine were analyzed using PAY/MWCNTs composite modified electrode and satisfactory results were obtained.

Biofuel cell and phenolic biosensor based on acid-resistant laccase–glutaraldehyde functionalized chitosan–multiwalled carbon nanotubes nanocomposite film

To immobilize laccase (Lac) from Trametes versicolor that shows its maximum enzymatic activity in acidic aqueous solutions, the biopolymer chitosan (CS) was chemically modified with glutaraldehyde (GA) to form GA functionalized CS (GAfCS), which was then allowed to react with Lac to form a Lac–GAfCS composite that is robust in weakly acidic solutions (two-step protocol), as confirmed by quartz crystal microbalance and durability tests. The Lac–GAfCS–multiwalled carbon nanotubes (MWCNTs)/glassy carbon (GC) electrode exhibited good catalytic activity towards O2 reduction in the presence of 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonate) diammonium salt (ABTS), and the pH-dependent enzymatic activity of the immobilized Lac towards O2 reduction was examined. A glucose/air biofuel cell was fabricated, with the Lac–GAfCS–MWCNTs/GC electrode as the biocathode and a glucose oxidase (GOx)–GAfCS–MWCNTs/GC electrode as the bioanode in a Nafion membrane-separated acetate buffer solution (pH 5.0). The biofuel cell output a maximum power density of 9.6μW/cm2, an open-circuit cell voltage of 0.19V, and a short-circuit current density of 114μA/cm2, respectively, as measured with an electrochemical noise (ECN) apparatus. Furthermore, the Lac–GAfCS–MWCNTs/GC electrode was applied to determine catechol in Britton–Robinson buffer solution (pH 3.0), with a linear range of 0.1–50μM and a limit of detection of 20nM. In comparison with the direct use of GA for one-pot Lac–GA-CS or Lac–GA crosslinking to immobilize Lac, the use of macromolecular GAfCS in the proposed two-step protocol was proven to be less harmful to the enzymatic activity and thus more suitable for immobilizing the enzyme to construct the biofuel cell and biosensor. This work may be helpful for exploiting the popular biocompatible CS as an acid-resistant film matrix for many other biotechnology applications, and the proposed two-step crosslinking protocol is recommended for high-activity immobilization of other biomolecules.