Nanoparticle-coated Carbon Nanotubes Research Articles

Remarkable improvement of wettability of Cu-coated carbon nanotubes by molten aluminum

The wettability plays a decisive role in the mechanical performances of the aluminum matrix composites reinforced with carbon nanotubes (CNTs). In this paper, novel Cu nanoparticles-coated CNTs (Cu@CNTs) were prepared successfully by the liquid phase reduction method to enhance the wettability of CNTs in aluminum melt. The microstructure, contact angle, and interfacial structure of aluminum liquid on Cu@CNTs substrate at high temperature were investigated by scanning electron microscopy (SEM) and sessile drop method in detail. By incorporating Cu nanoparticles on the surface of CNTs, the contact angle was reduced from 133° to 91°, indicating a significant improvement in the wettability of CNTs in aluminum melt. The atomic diffusion of Cu and Al elements leads to a remarkable improvement of wettability for Al-Cu@CNTs model. The coating of CNTs provides a new insight for strong wettability in high-performance aluminum matrix composites.

Stretchable Electrochemical Biosensing Platform Based on Ni-MOF Composite/Au Nanoparticle-Coated Carbon Nanotubes for Real-Time Monitoring of Dopamine Released from Living Cells

Existing electrochemical biosensing platforms, using traditional rigid and unstretchable electrodes, cannot monitor the biological signaling molecules released by cells in a mechanically deformed state in real time. Here, a stretchable and flexible electrochemical sensor was developed based on nickel metal-organic framework composite/Au nanoparticle-coated carbon nanotubes (Ni-MOF composite/AuNPs/CNTs) for sensitive detection of dopamine (DA) released by C6 living cells in real time. A Ni-MOF composite was obtained by introducing Ni, NiO, and a carbon frame onto the surface of two-dimensional (2D) Ni-MOF nanosheets using an efficient one-step calcination method. The hybrid of Ni-MOF composite/AuNPs/CNTs that deposited on the poly(dimethylsiloxane) (PDMS) film endowed the sensor with excellent electrochemical performance with a wide linear range of 50 nM to 15 μM and a high sensitivity of 1250 mA/(cm2 M) and also provided the sensor with desirable stability against mechanical deformation. Furthermore, the stretchable electrode also displayed good cellular compatibility while C6 living cells can be cultured and proliferated on it with strong adhesion. Then, the DA released by C6 living cells with chemical induction in both natural and stretched states was monitored using our stretchable and flexible electrochemical sensor in real time. This indicates that our new design of flexible Ni-MOF composite/AuNPs/CNTs/PDMS (NACP) film electrodes provides more opportunities for the detection of chemical signals released from cells and soft living organisms even under mechanically deformed states.

Flexible Array of Microsupercapacitor for Additive Energy Storage Performance Over a Large Area.

An on-chip microsupercapacitor (MSC) pattern is obtained by layer-by-layer spray deposition of both manganese dioxide (MnO2) nanoparticle-coated carbon nanotubes (MnO2-CNTs) and MnO2 nanosheet-decorated reduced graphene oxide (MnO2-rGO) on mechanically robust, flexible polyethylene terephthalate. Layer-by-layer patterning of MSC electrodes offers rapid in-plane diffusion of electrolyte ions in electrodes the layered electrode and hence ultrahigh capacitance and energy density of 7.43 mF/cm2 (32300 mF/cm3) and 0.66 μW h/cm2 (2870 μW h/cm3), respectively, are obtained. A robust electrochemical response was measured under multiple bending of the solid-state flexible MSC as well as under repetitive cycles (∼5000).

A study on the CNTs-Ag composites prepared based on spark plasma sintering and improved electroless plating assisted by ultrasonic spray atomization

Carbon nanotubes reinforced silver composites (CNTs-Ag composites) are considered as a promising candidate for high-performance contact materials with the potential properties of low contact resistance, high thermal conductivity and excellent mechanical performance. While at present the dispersion of CNTs in silver matrix and the interfacial bonding of the composites remain problems to be resolved or enhanced. In this study, silver nanoparticles coated carbon nanotubes (Ag@CNTs) were synthesized through an improved electroless plating method assisted by ultrasonic spray atomization, which inhibited excessive growth of silver particles and led to much more uniform nanometer grain-sized coating. The Ag@CNTs were solution ball-milled (SBM) with Ag powders and then were densified by spark plasma sintering (SPS). The composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDS). The results showed the CNTs dispersion in Ag matrix was improved benefitting from the homogeneous Ag nanoparticles distribution on CNTs, and correspondingly, the hardness and electrical conductivity were significantly improved. The mechanism may result from the combination of more homogeneous CNTs dispersion and tighter interface bonding in composite materials.

Development and characterization of PLA-mPEG copolymer containing iron nanoparticle-coated carbon nanotubes for controlled delivery of Docetaxel

The practicability of application of single wall carbon nanotubes doped with iron oxide nanoparticles (Fe3O4-iSWNTs) and coated with Poly (lactic acid)-co-methoxy polyethylene glycol copolymeric (PLA-co-mPEG) micelles as a smart drug delivery systems based on hybrid nanomaterials (HNDDSs) for the puissant chemotherapy agent Docetaxel (DTX) were studied. The SWNTs treatment in the acidic medium leads to formation of carboxylate groups on the surface of SWNTs and functionalization by iron oxide nanoparticles, Then PLA-co-mPEG was synthesized by ring-opening polymerization and prepared in the form of micelles and coated the Fe3O4-iSWNTs.The surface functionalization of nanomaterials and the type of surface-interaction were characterized by Fourier transform spectroscopy (FT-IR), proton nuclear magnetic resonance (H-NMR), X-ray powder diffraction (XRD), vibrating sample magnetometers (VSM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), field-emission gun scanning electron microscope and energy dispersive X-ray (FE-SEM-EDX). The particle size of nanocomposites examined by FE-SEM was in the range of 15–50 nm. The in-vitro drug release and cytotoxicity investigations of DTX loaded on Fe3O4-iSWNTs/PLA-co-mPEG nanocomposites were also studied. Docetaxel release in tumor environment simulated conditions showed sustained release manner (43.7% was released during 348.5 h) And kinetic mechanism of release according to log-probability equation. The designed nanocomposite showed no apparent evidence of toxicity to MCF7 cancer cells while DTX-loaded nanocomposites indicated enhanced antitumor activity in comparison to free DTX, 59% and 36% of the cells were viable after incubation, respectively. It was concluded that these findings may open the possibilities for targeted and sustained delivery of DTX to the cancerous tissues under external magnetic fields.

Flexible polyaniline/carbon nanotube nanocomposite film-based electronic gas sensors

Real-time ammonia (NH3) detection in anaerobic digestion is highly desirable, due to the ammonia inhibition on methane production. Here, the interconnected nanocomposite network of polyaniline (PANI) nanoparticle-coated carbon nanotube (CNT) and PANI nanofiber is fabricated by adding ammonium persulfate into CNT-containing aniline solution for PANI polymerization and film deposition. The film is assembled as high-sensitive ammonia sensors, exhibiting highly sensitive NH3 sensing from 200ppb to 50ppm, fast response/recovery time, room-temperature operation without external aid, reliable flexibility and excellent selectivity to NH3 compared to other volatile organic compounds.

CdS nanoparticle coated carbon nanotube through magnetron sputtering and its improved field emission performance

Carbon nanotubes (CNTs) are the most famous cold cathodes for display technology. However, graphene and other two dimensional carbon nanostructures and advanced II-VI semiconductor nanostructures are strongly emerging as strong competitors challenging the well established performance of CNTs in this field. Hence several technologies to improve field emission (FE) properties of CNTs are being developed. Here we report a facile technique to improve the cold emission performance of multiwalled CNTs (MWCNTs) by coating the same with chalcogenide semiconductor. MWCNT thin films were synthesized via chemical vapor deposition (CVD) technique and the same was coated by cadmium sulfide (CdS) nanoparticles via radio frequency magnetron sputtering technique. The pure and coated thin films were characterized by Fourier transform infrared spectroscopy and Raman spectroscopy to confirm presence of CdS on CNT surfaces. X-ray photoelectron spectroscopy revealed the compositional and valance state information of the as prepared samples. Field emission scanning electron microscopy and high resolution transmission electron microscopic studies were carried out to obtain information regarding morphology and nanocrystallinity of the CNTs and the coated CdS nanoparticles. Field assisted electron emission of pristine CNTs developed significantly with improved turn-on field and very high current density by CdS nanoparticle coating.

Gold Nanoparticle Coated Carbon Nanotube Ring with Enhanced Raman Scattering and Photothermal Conversion Property for Theranostic Applications.

We report a new type of carbon nanotube ring (CNTR) coated with gold nanoparticles (CNTR@AuNPs) using CNTR as a template and surface attached redox-active polymer as a reducing agent. This nanostructure of CNTR bundle embedded in the gap of closely attached AuNPs can play multiple roles as a Raman probe to detect cancer cells and a photoacoustic (PA) contrast agent for imaging-guided cancer therapy. The CNTR@AuNP exhibits substantially higher Raman and optical signals than CNTR coated with a complete Au shell (CNTR@AuNS) and straight CNT@AuNP. The extinction intensity of CNTR@AuNP is about 120-fold higher than that of CNTR at 808 nm, and the surface enhanced Raman scattering (SERS) signal of CNTR@AuNP is about 110 times stronger than that of CNTR, presumably due to the combined effects of enhanced coupling between the embedded CNTR and the plasmon mode of the closely attached AuNPs, and the strong electromagnetic field in the cavity of the AuNP shell originated from the intercoupling of AuNPs. The greatly enhanced PA signal and photothermal conversion property of CNTR@AuNP were successfully employed for imaging and imaging-guided cancer therapy in two tumor xenograft models. Experimental observations were further supported by numerical simulations and perturbation theory analysis.

Preparation and Characterization of Aligned Iron Oxide Carbon Nanotube Thin Film. Acta Physica Polonica A 125, 77 (2014), ERRATUM

Thin lms of acid-functionalized multiwall carbon nanotubes (O-MWCNT) with di erent concentrations and coated O-MWCNT with Fe3O4 nanoparticles (MWCNT/Fe3O4) were prepared on glass substrate at 300 ◦C by spray pyrolysis technique. In order to study the e ect of nanotubes alignment on the physical properties of carbon nanotube lms, thin lm of iron oxide nanoparticles coated carbon nanotubes was deposited under magnetic eld of 0.4 T. All samples were characterized using UV Vis spectroscopy, X-ray di raction, scanning electron microscopy, and the Hall e ect experiment. Results show that the electrical conductivity and optical transmittance of carbon nanotubes thin lms depend on the concentration of carbon nanotubes and their arrangement at the lms. Aligning carbon nanotubes in thin lms leads to an obvious improvement in electrical and optical properties of thin lms.

Preparation and Characterization of Aligned Iron Oxide Carbon Nanotube Thin Film

Thin lms of acid-functionalized multiwall carbon nanotubes (O-MWCNT) with di erent concentrations and coated O-MWCNT with Fe3O4 nanoparticles (MWCNT/Fe3O4) were prepared on glass substrate at 300 ◦C by spray pyrolysis technique. In order to study the e ect of nanotubes alignment on the physical properties of carbon nanotube lms, thin lm of iron oxide nanoparticles coated carbon nanotubes was deposited under magnetic eld of 0.4 T. All samples were characterized using UV Vis spectroscopy, X-ray di raction, scanning electron microscopy, and the Hall e ect experiment. Results show that the electrical conductivity and optical transmittance of carbon nanotubes thin lms depend on the concentration of carbon nanotubes and their arrangement at the lms. Aligning carbon nanotubes in thin lms leads to an obvious improvement in electrical and optical properties of thin lms.

Facile synthesis of titania nanoparticles coated carbon nanotubes for selective enrichment of phosphopeptides for mass spectrometry analysis

In this work, titania nanoparticles coated carbon nanotubes (denoted as CNTs/TiO2 composites) were synthesized through a facile but effective solvothermal reaction using titanium isopropoxide as the titania source, isopropyl alcohol as the solvent and as the basic catalyst in the presence of hydrophilic carbon nanotubes. Characterizations using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) indicate that the CNTs/TiO2 composites consist of CNT core and a rough outer layer formed by titania nanoparticles (5–10nm). Measurements using wide angle X-ray diffraction (WAXRD), zeta potential and N2 sorption reveal that the titania shell is formed by anatase titania nanoparticles, and the composites have a high specific surface area of about 104m2/g. By using their high surface area and affinity to phosphopeptides, the CNTs/TiO2 composites were applied to selectively enrich phosphopeptides for mass spectrometry analysis. The high selectivity and capacity of the CNTs/TiO2 composites have been demonstrated by effective enrichment of phosphopeptides from digests of phosphoprotein, protein mixtures of β-casein and bovine serum albumin, human serum and rat brain samples. These results foresee a promising application of the novel CNTs/TiO2 composites in the selective enrichment of phosphopeptides.

Self-deposition of Pt nanocrystals on Mn3O4 coated carbon nanotubes for enhanced oxygen reduction electrocatalysis

Developing catalysts with high electrocatalytic activity for oxygen reduction reaction (ORR) has recently attracted much attention because the sluggish ORR limits the performance and commercialization of current PEMFCs and metal–air batteries as well. Herein, a facile approach was reported to synthesize Mn3O4 nanoparticle coated carbon nanotubes (Mn3O4/CNTs) and self-deposit well-dispersed Pt nanocrystals on Mn3O4/CNTs to obtain Pt/Mn3O4/CNTs hybrid catalysts via in situ reduction of support matrix with no need of any capping agent and additional reducing agent. As a result of good dispersion of uncapped Pt nanocrystals, interconnected carbon nanotube conductive network, and possible synergetic co-catalytic effect from heterojunction interfaces of Pt nanocrystals and Mn3O4, the as-prepared Pt/Mn3O4/CNTs hybrid catalysts demonstrated much enhanced electrocatalytic activity for ORR. The reported strategy may inspire the development of new high efficient hybrid electrocatalysts in a cost-effective way with the potential to harness the metal/oxide interaction to improve the performance of catalysts.

Preparation and Electromagnetic Wave Absorption Properties of Carbon Nanotubes-Titanium Dioxide Nanoparticles

A novel titanium dioxide （TiO2） nanoparticles coated carbon nanotubes (CNTs) composites were prepared by sol-gel method as microwave absorbing materials in this paper. SEM and XRD researches show that sol-gel method can realize uniform coating of CNTs with TiO2. Among them, with the weight fraction of TiO2/ CNTs composites was 10%, microwave absorption characteristics with a minimum RL value of -34 dB at 6.2 GHz on a coating with a matching thickness of 4mm and <−10 dB was obtained in the frequency range of 4.5-18 GHz with the thickness of 1.5-5.0mm.

Preparation and Electromagnetic Wave Absorption Properties of Carbon Nanotubes-Titanium Dioxide Nanoparticles

A novel titanium dioxide （TiO2） nanoparticles coated carbon nanotubes (CNTs) composites were prepared by sol-gel method as microwave absorbing materials in this paper. SEM and XRD researches show that sol-gel method can realize uniform coating of CNTs with TiO2. Among them, with the weight fraction of TiO2/ CNTs composites was 10%, microwave absorption characteristics with a minimum RL value of -34 dB at 6.2 GHz on a coating with a matching thickness of 4mm and &lt;−10 dB was obtained in the frequency range of 4.5-18 GHz with the thickness of 1.5-5.0mm.

Simultaneous electrochemical immunoassay of three liver cancer biomarkers using distinguishable redox probes as signal tags and gold nanoparticles coated carbon nanotubes as signal enhancers

A novel strategy for simultaneous determination of three liver cancer biomarkers based on three redox labels with distinct voltammetric peaks was described. Gold nanoparticles coated carbon nanotubes were used as carriers to immobilize redox probes labeled antibodies and to amplify the signals.

Coating multiwalled carbon nanotubes with gold nanoparticles derived from gold salt precursors

Derived gold nanoparticles supported on carbon nanotubes were generated via local reduction of AuCl 4 − ions, which are ion-paired with 3-aminopropyltriethoxysilane that are chemically attached to carbon nanotubes. The controllable loading of gold nanoparticles on carbon nanotubes can be tuned by regenerative ion exchange and subsequent reduction. This method is not limited to gold, however, it may be used to assemble a variety of other metal nanoparticles on surfaces of the modified carbon nanotubes. Transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction are all used to characterize the as-prepared gold nanoparticle coated carbon nanotube hybrids. The hybrids show characteristic plasmon absorption of gold nanoparticles in the UV–visible spectrum and very good electrochemical properties. The results imply that these nanohybrids may have a good application potential in catalysis, sensor, and fuel cells.

Influence of metal nanoparticle decorated CNTs on polyurethane based electro active shape memory nanocomposite actuators

Polymer nanocomposites based on thermoplastic polyurethane (PU) elastomer and metal nanoparticle (Ag and Cu) decorated multiwall carbon nanotubes (M-CNTs) were prepared through melt mixing process and investigated for its mechanical, dynamic mechanical and electro active shape memory properties. Structural characterization and morphological characterization of the PU nanocomposites were done using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Morphological characterization revealed better dispersion of M-CNTs in the polyurethane, which is attributed to the improved interaction between the M-CNTs and polyurethane. Loading of the metal nanoparticle coated carbon nanotubes resulted in the significant improvement on the mechanical properties such as tensile strength of the PU composites in comparison to the pristine carbon nanotubes (P-CNTs). Dynamic mechanical analysis showed that the glass transition temperature (Tg) of the polyurethane increases slightly with increasing loading of both pristine and metal nanoparticle functionalized carbon nanotubes. The metal nanoparticles decorated carbon nanotubes also showed significant improvement in the thermal and electrical conductivity of the PU/M-CNTs nanocomposites. Shape memory studies of the PU/M-CNTs nanocomposites exhibit remarkable recoverability of its shape at lower applied dc voltages.

A Direct Route toward Assembly of Nanoparticle−Carbon Nanotube Composite Materials

The preparation of nanocomposite materials from carbon nanotubes (CNTs) and metal or metal oxide nanoparticles has important implications to the development of advanced catalytic and sensory materials. This paper reports findings of an investigation of the preparation of nanoparticle-coated carbon nanotube composite materials. Our approach involves molecularly mediated assembly of monolayer-capped nanoparticles on multiwalled CNTs via a combination of hydrophobic and hydrogen-bonding interactions between the capping/mediating shell and the CNT surface. The advantage of this route is that it does not require tedious surface modification of CNTs. We have demonstrated its simplicity and effectiveness for assembling alkanethiolate-capped gold nanoparticles of 2-5 nm core sizes onto CNTs with controllable coverage and spatially isolated character. The loading and distribution of the nanoparticles on CNTs depend on the relative concentrations of gold nanoparticles, CNTs, and mediating or linking agents. The composite nanomaterials can be dispersed in organic solvent, and the capping/linking shells can be removed by thermal treatment to produce controllable nanocrystals on the CNT surfaces. The nanocomposite materials are characterized using transmission electron microscopy and Fourier transform infrared spectroscopy techniques. The results will be discussed in terms of developing advanced catalytic and sensory nanomaterials.