Decorated Carbon Nanotubes Research Articles

Development of 4-methoxyphenol chemical sensor based on NiS2-CNT nanocomposites

Nickel disulphide decorated carbon nanotube nanocomposites (NiS2-CNT NCs) was synthesized by the wet-chemical method in alkaline medium. Characterization of the resulting NiS2-CNT NCs was performed in details by field emission scanning electron microscopy (FESEM) attached with energy-dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), UV/vis. spectroscopy, FT-IR spectroscopy, and X-ray diffraction pattern (XRD). Glassy carbon electrode (GCE; Surface area: 0.0316cm2) was fabricated with NiS2-CNT NCs and developed in chemical sensing performance by a simple and reliable I-V method. Toxic chemical 4-methoxyphenol (4-MP) was used as a target analyte in selectivity study, which exhibits a fast response towards NiS2-CNT NCs fabricated GCE sensor by the I-V method. It also displayed an excellent sensitivity, lower-detection limit, large linear dynamic range, long-term stability, and reproducibility. In analytical investigation, the calibration plot was found linear (r2: 0.8744) over a large concentration range (from 0.1nM to 10.0mM), where the sensitivity was around 632.9224µAmM−1cm−2 with a very low detection limit (LOD) of 30.0±0.02pM (Based on the S/N=3). Potentials of NiS2-CNT NCs in terms of chemical sensing are also discussed in this report. This approach is introduced as a well-organized route of efficient phenolic sensor development in environmental and healthcare fields in broad scales.

Decorating carbon nanotubes with co-precipitated magnetite nanocrystals

The superior properties of carbon nanotubes (CNTs) are best manifest in bulk materials when the CNTs are organized in tandem and embedded in a continuous matrix. Decorating the CNTs with magnetic nanoparticles (MNPs) facilitates their expedient organization with a magnetic field. One of the most convenient methods for their decoration is to first treat the CNTs with nitric or sulfuric acid, or a mixture of the two, and then co-precipitate MNPs in situ. Here, six variations of this protocol are compared to identify their influence on the decoration of multi-walled CNTs (MWNTs). Acid-treated MWNTs are scrutinized using XPS, and the decorated MWNTs are examined using X-ray diffraction, transmission electron microscopy, Fourier transformer infrared spectroscopy and vibrating sample magnetometry. The results show that (1) treatment with nitric acid provides the highest (~100%) attachment of MNPs to the MWNT walls, (2) sulfuric acid best preserves the MWNTs with only ~8% weight loss, and (3) after acid-treatment, the MWNTs must be washed and filtered prior to co-precipitation to prevent the consumption of up to 70% of the iron through side reactions that yield non-magnetic phases.

Platinum nanoparticles decorated carbon nanotubes for highly sensitive 2-nitrophenol chemical sensor

Herein, we report the successful preparation and characterization of platinum nanoparticles decorated carbon nanotubes. The Pt nanoparticles were deposited on the surfaces of carbon nanotubes (CNTs) using RF magnetron sputtering technique under inert gas atmosphere. The prepared Pt nanoparticles decorated CNTs were characterized in detail using several techniques in terms of their morphological, structural and compositional properties. Further, the Pt-decorated CNT nanocomposites were used as efficient redox mediators for the fabrication of 2-nitrophenol chemical sensor. The fabricated 2-nitrophenol chemical sensor exhibited a very high-sensitivity of ~395.234μAmM−1cm−2 and a low detection limit of 2.19mM. The observed linear dynamic range (LDR) of the fabricated sensor was 0.156–2.5mM with a regression coefficient of ~0.99273. The observed results demonstrate that the Pt nanoparticles decorated CNTs are efficient electron mediator to fabricate highly sensitive chemical sensors.

Electrophoretically‐Deposited Metal‐Decorated CNT Nanoforests with High Thermal/Electric Conductivity and Wettability Tunable from Hydrophilic to Superhydrophobic

A single‐step, room‐temperature, and scalable electrophoretic deposition process is reported to form nanocomposites on any electrically conductive surface with metal nanoparticle decorated carbon nanotubes (CNTs). The contact angles (CAs) can be easily tuned from ≈60° to 168° by varying the deposition voltage, while hydrophobicity and superhydrophobicity surprisingly arise from the hydrophilic CNTs being deposited. The relatively high voltage tends to vertically align CNTs during deposition, leading to architectural micro/nanoscale roughness on the surface. The combination of the multiscale roughness along with the low surface energy of hydrocarbon functional groups on the CNT surface has enabled facile wettability control, including the Petal and Lotus effects. Further, the relatively vertical orientation of the CNTs, without any coating, allows for current and heat transfer along their axis with superior conductivity. Similar behavior in terms of CA control is seen for all three divalent metal ions in the deposition solution (i.e., Cu2+, Ni2+, and Zn2+) that are used to charge the CNTs while eventually getting co‐deposited. This implies that this method could possibly be extended to other metals by selecting appropriate charging salt. A patterning technique is also demonstrated for facile fabrication of superhydrophobic CNT‐metal islands surrounded by hydrophilic CNT coating.

A gold electrode modified with silver oxide nanoparticle decorated carbon nanotubes for electrochemical sensing of dissolved ammonia

We have prepared silver oxide nanoparticles with a diameter of ~ 15 nm and decorated with carbon nanotube nanocomposites (Ag2O/CNT NCs) by a facile wet chemical method using reducing agents in alkaline medium. These NCs were characterized by UV/vis, FTIR and energy dispersive X-ray spectroscopy, by X-ray powder diffraction and field emission scanning electron microscopy. The NCs were then deposited on a flat gold electrode with the help of a conducting binder to result in an electrochemical sensor for aqueous ammonia using the I-V technique. Response is based on surface oxidation of ammonium hydroxide with electrode-adsorbed oxygen to form nitrogen oxide, these simultaneously liberating free electrons in the conduction band. Sensor features include a sensitivity of 32.856 μA.μM‾1.cm‾2, a low detection limit (1.3 pM at a signal to noise ratio of 3), reliability, reproducibility, ease of integration, and long term stability. The response to dissolved ammonia is linear (r2: 0.9778) over the 0.01 nM to 0.1 mM concentration range.

Simultaneous deposition of carbon nanotubes and decoration with gold–palladium nanoparticles by laser-induced forward transfer

Decorating carbon nanotubes (CNTs) with nanoparticles has proved to be an intelligent approach to improve the gas adsorption properties of CNTs for the development of new sensors, including hydrogen sensors. However, in order to take advantage of this hybrid structure, methods are needed that ensure a proper decoration and the fabrication of small features without compromising the sensing surface. Within this paper, we report a novel technique to simultaneously decorate multiwall carbon nanotubes (MWCNTs) with gold–palladium nanoparticles and transfer them to a substrate by laser-induced forward transfer using femtosecond laser pulses. The nanoparticles decorating the MWCNTs present a spherical shape with a Feret diameter bellow 200 nm. The nanoparticle size can be tuned by varying the amount of pulses within the transfer. Finally, hydrogen adsorption showed up to a 20-fold increase compared to a sample composed of non-transferred, non-decorated MWCNTs.

Decoration of Carbon Nanotubes by Semiconducting or Metallic Nanoparticles using Fluidized Bed Chemical Vapour Deposition

Multi-Walled Carbon Nanotubes (MWCNTs) have promising properties that make them potentially useful in a wide variety of applications. The decoration of MWCNTs by metallic or semiconducting nanoparticles aims to intensify some of their properties, in particular thermal and electrical conductivity. Fluidized Bed Chemical Vapour Deposition (FBCVD) is an efficient process to uniformly coat powders by various materials. The coating by SnO2, Fe and Si nanoparticles of MWCNTs (Graphistrength®) tangled in balls of 360 microns in mean diameter using the FBCVD process has been studied. The influence of some deposition parameters with and without oxidative pre-treatment is analysed on the nucleation and growth of nanoparticles. The various results obtained indicate that the intrinsic surface reactivity of MWCNTs is high enough for CVD precursors involving the formation of highly reactive unsaturated species such as silylene SiH2 formed from silane SiH4 pyrolysis in the case of Si deposition. But it must be enhanced for less reactive CVD precursors such as tin tetrachloride SnCl4 which needs the presence of oxygen-containing groups at the nanotube surface to allow Sn nucleation. So, provided the reactivity of the powder surface and that of the CVD precursors are well tuned, the FBCVD process can uniformly coat the outer surface of MWCNTs by metallic or semiconducting nanoparticles.

Review—The Development of Gas Sensor Based on Carbon Nanotubes

Carbon nanotubes (CNTs) are one of the carbon nanomaterial that is very popular in the field of gas sensors. It has unique properties, large surface area and hollow structure that makes its potentially applicability for using as a gas sensor. Several attempts have been made to improve the sensing performances of carbon nanotubes including the sensitivity and selectivity of CNTs by modifying CNTs with a noble metals, metal oxides and polymers. From these studies, there are evident that the modifications of CNTs with certain materials can improve the sensitivity and selectivity of CNTs for the sensor applications for several harmful gases. Decorating carbon nanotubes with metal oxides can improve the CNTs to reach the highest sensitivity. Moreover the increasing sensitivity of polymer/ CNTs is higher than the metal/CNTs. The modification of metal in CNTs aims to accelerate the reaction surface and as channel for electrons path from or to the CNTs. Therefore the used of metal oxides on CNTs built a p-n junction that can increase sensitivity. Subsequently the addition of polymer can increase the charge carrier density in CNTs.

Improved electromagnetic wave absorption of Co nanoparticles decorated carbon nanotubes derived from synergistic magnetic and dielectric losses.

In this study, we report a feasible way to synthesize carbon nanotube nanocomposites deposited with cobalt nanoparticles (20-30 nm) on the surface (Co/CNTs) to serve as an electromagnetic (EM) wave absorption material. EM absorption measurements indicated that epoxy resin composites with 20 wt% Co/CNTs exhibited an effective EM absorption (RL < -10 dB) in the frequency range of 2.5-20 GHz with an absorber thickness of 1.0 to 6.0 mm. A strong absorption peak (RL = -36.5 dB) appeared at 4.1 GHz as the thickness was 4.0 mm, and the absorption bandwidth (RL < -10 dB) was in the frequency range of 3.6-4.6 GHz. The electromagnetic loss research suggested that the superior EM absorption performances including a light weight, strong absorption, broad frequency scope, and thin thickness could be ascribed to the synergistic effect of magnetic loss from Co nanoparticles and the dielectric loss of CNTs, resulting in better impedance matching.

Benzene Removal by Iron Oxide Nanoparticles Decorated Carbon Nanotubes

In this paper, carbon nanotubes (CNTs) impregnated with iron oxide nanoparticles were employed for the removal of benzene from water. The adsorbents were characterized using scanning electron microscope, X-ray diffraction, BET surface area, and thermogravimetric analysis. Batch adsorption experiments were carried out to study the adsorptive removal of benzene and the effect of parameters such as pH, contact time, and adsorbent dosage. The maximum removal of benzene was 61% with iron oxide impregnated CNTs at an adsorbent dosage 100 mg, shaking speed 200 rpm, contact time 2 hours, initial concentration 1 ppm, and pH 6. However, raw CNTs showed only 53% removal under same experimental conditions. Pseudo-first-order kinetic model was found well to describe the obtained data on benzene removal from water. Initial concentration was varied from 1 to 200 mg/L for isotherms study. Langmuir isotherm model was observed to best describe the adsorption data. The maximum adsorption capacities were 987.58 mg/g and 517.27 mg/g for iron oxide impregnated CNTs and raw CNTs, respectively. Experimental results revealed that impregnation with iron oxide nanoparticles significantly increased the removal efficiency of CNTs.

Carbide decorated carbon nanotube electrocatalyst for high-efficiency hydrogen evolution from seawater

Co3Mo3C/CNT electrocatalysts are developed for high-efficiency hydrogen evolution by seawater splitting.

Magnetic Carbon Paste Electrode Modified with a High Performance Composite Based on Molecularly Imprinted Carbon Nanotubes for Sensitive Determination of Levofloxacin

A selective electrochemical sensor based on molecularly imprinted magnetite decorated carbon nanotubes (MCNTs@MIP) was developed for the determination of levofloxacin (Lv). The preparation of molecularly imprinted polymers was performed using Lv as template, MCNTs as support, methacrylic acid as functional monomer and ethylene glycol dimethacrylate as cross-linker. Fourier transform infrared spectroscopy and scanning electron microscopy were used to characterize the composites structures. The resulting MCNTs@MIP were suspended in Lv solution and then collected on the surface of a carbon paste electrode via a permanent magnet, situated within the carbon paste electrode and then the voltammetry signals were recorded. Under the optimized experimental conditions, a linear response was obtained in the range of 0.003–0.440 μM with a detection limit of 0.8 nM. The applicability of the method for complex matrix analysis was also evaluated and the modified electrode showed good stability and reproducibility.

A novel approach towards hydrazine sensor development using SrO·CNT nanocomposites

Strontium oxide nanoparticle decorated carbon nanotube nanocomposites (SrO·CNT NCs) were prepared in alkaline medium using a wet-chemical technique at low temperature.

Cobalt nickel phosphide nanoparticles decorated carbon nanotubes as advanced hybrid catalysts for hydrogen evolution

Cobalt nickel phosphide nanoparticle decorated carbon nanotubes (Co2−xNixP/CNTs) as efficient hybrid catalysts for enhanced hydrogen evolution reaction catalytic activity.

CoFe2O4-decorated carbon nanotubes for the dehydration of glucose and fructose

Carbon nanotubes were decorated with various ferrites of normal and inverse spinels and were characterized using XRD, Raman, SEM and TEM analysis. The inverse-spinel-decorated CNTs were successfully evaluated in the dehydration of glucose and fructose.

Iron–cobalt bimetal decorated carbon nanotubes as cost-effective cathode catalysts for Li–O2batteries

FeCo bimetal decorated CNTs were synthesized as highly efficient and cost-effective non-noble metal catalysts for Li-O2batteries.

The "click-on-tube" approach for the production of efficient drug carriers based on oxidized multi-walled carbon nanotubes.

To demonstrate the potential of azido-substituted carbon nanotubes for application in nanomedicine, multiple-decorated oxidized multi-walled carbon nanotubes as drug delivery systems have been synthesized. These DDSs were able to carry doxorubicin inside breast MCF-7 cancer cell lines resulting in an enhanced cytotoxic effect with respect to the free drug. Decoration of the carbon nanotubes was accomplished through both covalent and non-covalent approaches: versatile click reactions and π-π interactions were exploited. To assess the internalization of the carbon nanotubes inside cells, decoration with a BODIPY fluorescent molecule was performed. Furthermore, the nanotubes were decorated with a biotin selector molecule to increase the uptake of the system by cancer cells. Comparative studies were performed on the complete drug delivery system to highlight its effect with respect to the free drug and the contribution of the selector in the internalization efficiency. Finally, preliminary in vivo tests were performed on MCF-7 inoculated mice. A net improvement in efficiency, concerning the minor growth of the tumors, has been found when using doxorubicin loaded on our drug delivery system with respect to free doxorubicin.

Progammed synthesis of magnetic mesoporous silica coated carbon nanotubes for organic pollutant adsorption

Magnetic mesoporous silica coated carbon nanotubes were produced from hydrophilic monodisperse magnetic nanoparticles decorated carbon nanotubes using well controlled programmed synthesis method and were characterized by TEM, XRD, FTIR, TGA, N2 adsorption–desorption and VSM. The well-designed mesoporous magnetic nanotubes had a large specific area, a highly open mesoporous structure and high magnetization. Firstly, SiO2-coated maghemite/CNTs nanoparticles (CNTs/Fe3O4@SiO2 composites) were synthesized by the combination of high temperature decomposition process and an sol–gel method, in which the iron acetylacetonate as well as TEOS acted as the precursor for maghemite and SiO2, respectively. The CNTs/Fe3O4@SiO2 composites revealed a core–shell structure, Then, CNTs/Fe3O4@mSiO2 was obtained by extracting cetyltrimethylammonium bromide (CTAB) via an ion-exchange procedure. The resulting composites show not only a magnetic response to an externally applied magnetic field, but also can be a good adsorbent for the organic pollutant in the ambient temperature.

Hierarchical oil–water separation membrane using carbon fabrics decorated with carbon nanotubes

Abstract The study adopts an efficient spin-coating method to disperse fluorinated carbon nanotubes (CNTs) onto carbon fabrics (CFs) as hierarchical oil–water separation membrane. The topography observation indicates that multi-walled CNTs with an average diameter of 30–50 nm are coated over the CF surface, forming a nano/submicron scaled roughness. The CNT–CF membrane exhibits superhydrophobic behavior (water contact angle: 165°), low wetted surface fraction (5.5%), and low work of adhesion ( W ad : 2.5 mJ/m 2 ). The oil–water separation efficiency of CNT–CF membrane can reach to 99.7%, better than the CF membrane without the CNT decoration. The robust design of CNT–CF membranes enhances not only the oil–water separation efficiency but also the permeability. The enhanced efficiency can be ascribed to the fact that the decoration of fluorinated CNTs is capable of lowering roll-off kinetic energy barrier, proved by the oil–water separation mechanism. Accordingly, the difference of W ad values between oil and water droplets can be taken into account as a crucial index for evaluating the separation efficiency, favoring the development of oil–water separators and filtration units in the future.

Synthesis and Characterization of Au NPs/Molybdophosphoric Acid/CNT Tricomponent Nanohybrid

In the present study, hybrids of gold nanoparticle-decorated multiwalled carbon nanotubes (CNTs) were synthesized through an effective, green and facile method, using molybdophosphoric acid. This polyoxometalate with exciting properties was used as reducing agent in the synthesis of stabilized gold nanoparticles and also linking them to the CNTs at ambient temperature. The prepared nanohybrids were characterized by TGA, XRD, FTIR, Raman, and TEM techniques. Using this method, a yield of 17% in CNTs decoration with a well distribution of nanoparticles is satisfactorily achieved within 8 h.