Carbon Nanotube Hybrid Nanocomposites Research Articles

Self-affinity of AuNPs on polyethyleneimine (PEI) functionalized polypyrrole-derived carbon nanotubes hybrid nanocomposite: A novel interference-free electrochemical sensing platform for caffeine detection

Heterogeneous composite materials have drawn considerable attention for their synergistic effects and are anticipated to provide high-performance electrochemical sensing. In the present study, a simple, sensitive, and selective electrochemical sensor for the determination of caffeine (CAF) was developed by using carbon-rich polypyrrole nanotubes (PPy NTs) derived carbon nanotubes (PPy CNTs) via direct pyrolysis strategy without structural degradation loaded with AuNPs by in situ chemical route via hydrogen bonding with polyethyleneimine (PEI) to obtained [email protected] NTs and [email protected] CNTs hybrid nanocomposites. Subsequently immobilized on a glassy carbon electrode (GCE) to construct [email protected] NTs/GCE and [email protected] CNTs/GCE electrochemical sensors that could be directly used to measure caffeine in beverages and pharmaceuticals using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Interestingly, [email protected] CNTs modified sensors showed exceptional electrocatalytic effects on CAF oxidation with a significantly increased peak current (∼4.5-fold) than an [email protected] NTs/GCE sensor. The electrode material exhibited linear responses in the concentration ranges 50 nM to 500 µM and 10 nM to 10 mM with detection limits of 14.2 and 2.8 nM (S/N = 3) for the [email protected] NTs/GCE and [email protected] CNTs/GCE, respectively. The fabricated electrode displayed a low detection limit, wide linear range, excellent selectivity, stability, and high reproducibility (2.37 % RSD for seven prepared sensors). The proposed method was successfully applied to determine caffeine in actual samples such as tea, coffee, and energy drinks without sample pretreatments, with recoveries ranging from 92.36 to 117.1 %. Therefore, the present electrode has excellent potential for sensitive and straightforward determination of caffeine in actual samples.

The role of multiwall carbon nanotubes on physical, mechanical and rheological properties of poly(lactic acid)/natural rubber/CNT hybrid systems

The main objective of the present work was to study the role of carbon nanotube (CNT) on the microstructure development and physical, mechanical, and rheological properties of poly(lactic acid) (PLA)/natural rubber (NR)/CNT hybrid nanocomposites. The PLA/NR blend samples with constant blend ratio (90/10) were prepared by melt mixing in a laboratory internal mixer at a temperature of 190°C. The behavior of the PLA/NR blend was examined depending on the CNT content (0.5–6 wt%). The droplet size and droplet size distribution of the NR phase decreases with the increase in CNTs content. This could be explained in terms of compatibilizing effect of CNT and the changing of the viscosity ratio of the blend phases. The development of the microstructure and the physical properties of the blend were also investigated according to the CNT contents by measuring the linear viscoelasticity. The elongational behavior and mechanical properties of the blends were strongly dependent on the location of the CNT. The CNT worked as an efficient compatibilizer and also it worked as a reinforcing filler making the matrix more rigid.

Simultaneous Determination of Four DNA bases at Graphene Oxide/Multi-Walled Carbon Nanotube Nanocomposite-Modified Electrode.

In this study, we developed a modified glassy carbon electrode (GCE) with graphene oxide, multi-walled carbon nanotube hybrid nanocomposite in chitosan (GCE/GO-MWCNT-CHT) to achieve simultaneous detection of four nucleobases (i.e., guanine (G), adenine (A), thymine (T) and cytosine (C)) along with uric acid (UA) as an internal standard. The nanocomposite was characterized using TEM and FT-IR. The linearity ranges were up to 151.0, 78.0, 79.5, 227.5, and 162.5 µM with a detection limit of 0.15, 0.12, 0.44, 4.02, 4.0, and 3.30 µM for UA, G, A, T, and C, respectively. Compared to a bare GCE, the nanocomposite-modified GCE demonstrated a large enhancement (~36.6%) of the electrochemical active surface area. Through chronoamperometric studies, the diffusion coefficients (D), standard catalytic rate constant (Ks), and heterogenous rate constant (Kh) were calculated for the analytes. Moreover, the nanocomposite-modified electrode was used for simultaneous detection in human serum, human saliva, and artificial saliva samples with recovery values ranging from 95% to 105%.

Selective photocurrent generation in HfO2 and carbon nanotube hybrid nanocomposites under Ultra-Violet and visible photoexcitations

We report on the photocurrent generation in HfO2-carbon nanotube (CNT) nanocomposites under Ultra-Violet (UV) and visible excitations at zero bias. Cubic phase HfO2 nanoparticles have been combined with multi-walled carbon nanotubes in this work. The cubic phase of HfO2 has been stabilized by oxygen vacancies which act as luminescent band gap states. In a broad UV–visible range of below band gap photoexcitation, a photocurrent is generated which was found to be most efficient under UV illumination. We discuss the possible mechanism in terms of a CNT assisted charge transfer involving optically active surface states of the HfO2 nanoparticles. The abrupt generation and relaxation responses of the photocurrent on/off cycles along with a constant steady state current as high as 200 nA for 1 mg of the nanocomposite, has potential in energy harvesting and other applications requiring stable charge retention.

Synthesis of polydopamine-functionalized magnetic graphene and carbon nanotubes hybrid nanocomposites as an adsorbent for the fast determination of 16 priority polycyclic aromatic hydrocarbons in aqueous samples.

A novel adsorbent made of polydopamine-functionalized magnetic graphene and carbon nanotubes hybrid nanocomposite was synthesized and applied to determine 16 priority polycyclic aromatic hydrocarbons by magnetic solid phase extraction in water samples. FTIR spectroscopy, transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy consistently indicate that the synthesized adsorbents are made of core-shell nanoparticles well dispersed on the surface of graphene and carbon nanotubes. The major factors affecting the extraction efficiency, including the pH value of samples, the amount of adsorbent, adsorption time and desorption time, type and volume of desorption solvent, were systematically optimized. Under the optimum extraction conditions, a linear response was obtained for polycyclic aromatic hydrocarbons between concentrations of 10 and 500ng/L with the correlation coefficients ranging from 0.9958 to 0.9989, and the limits of detection (S/N=3) were between 0.1 and 3.0ng/L. Satisfactory results were also obtained when applying these magnetic graphene/carbon nanotubes/polydopamine hybrid nanocomposites to detect polycyclic aromatic hydrocarbons in several environmental aqueous samples.

Polypyrrole with a functionalized multi-walled carbon nanotube hybrid nanocomposite: a new and efficient nitrite sensor

This study mainly focuses on the electrochemical-assisted synthesis of conducting polymers such as polypyrrole (PPy) with sodium dodecyl sulfate (SDS) as a surfactant and supported with functionalized multi-walled carbon nanotubes (f-MWCNTs).

(Invited) Semiconducting Polymer-Semiconducting Single-Walled Carbon Nanotubes Hybrid Nanocomposites

Semiconducting single-walled carbon nanotubes (SWNTs) show promise as core materials for next-generation solar cells and nanoelectronic devices. However, most commercial SWNT production methods generate mixtures of metallic SWNTs (m-SWNTs) and semiconducting SWNT (sc-SWNTs). Therefore, sc-SWNTs must be separated from their original mixtures before use. In this study, we investigated a polymer-based, noncovalent sc-SWNT separation approach, which is simple to perform and does not disrupt the electrical properties of the SWNTs, thus improving the performance of the corresponding sc-SWNT-based applications. By systematically investigating the effect that different structural features of the semiconductor polymers have on the separation of sc-SWNTs, we discovered that the length and configuration of the alkyl side chains and the rigidity of the backbone structure exert significant effects on the efficiency of sc-SWNT separation. We also found that electron transfer between the semiconducting polymers and sc-SWNTs is strongly affected by their energy-level alignment, which can be tailored by controlling the donor-acceptor configuration in the polymer backbone structures. Among the polymers investigated, the highly planar P8T2Z-C12 semiconducting polymer showed the best sc-SWNT separation efficiency and unprecedentedly strong electronic interaction with the sc-SWNTs, which is important for improving their performance in applications.

UHMWPE Hybrid Nanocomposites for Improved Tribological Performance Under Dry and Water-Lubricated Sliding Conditions

To tap the full potential of polymers to be used as tribo-materials under water lubrication, it is very important to improve their resistance to water uptake on the one hand and improve their strength and load bearing capacity on the other so that their performance under these conditions is not deteriorated. Hence, a unique approach of fabricating a hybrid polymer nanocomposite reinforced with nanoclay for improving the resistance to water uptake and carbon nanotubes (CNTs) to improve the mechanical/tribological properties is undertaken. Ultrahigh molecular weight polyethylene (UHMWPE) hybrid nanocomposites were fabricated via ball milling followed by hot pressing method. Functionalized multi-wall CNTs and C15A organoclay were used as nanofillers in UHMWPE matrix. Hybrid nanocomposites were developed with CNT loadings of 0.5, 1.5 and 3.0 wt% while keeping C15A organoclay content fixed at an optimized value of 1.5 wt%. Initially, the hybrid nanocomposites were optimized under dry sliding conditions whereby a loading of 1.5 wt% of CNTs and 1.5 wt% C15A organoclay resulted in the maximum reduction in the specific wear rate by about 64% as compared to pristine UHMWPE. Later, tribological performance of the optimized hybrid nanocomposite was compared with pristine UHMWPE and its UHMWPE nanocomposites under water-lubricated conditions sliding against a 440C stainless steel ball for 150,000 cycles. The specific wear rate showed a reduction by ~46% for the 1.5 wt% CNTs hybrid nanocomposites as compared to pristine UHMWPE under water lubrication. The improved resistance to wear was attributed to the uniform dispersion of both the nanofillers, namely CNTs and C15A organoclay which effectively increased the load bearing capacity of UHMWPE. Moreover, the excellent barrier properties of the platelet-like structure of C15A clay which presented a torturous path for the diffusion of the water molecule in UHMWPE reduced the softening of the surface layer leading to better resistance to wear under water lubrication.

Spinel MnCo2O4/N,S‐doped Carbon Nanotubes as an Efficient Oxygen Reduction Reaction Electrocatalyst

AbstractThe development of inexpensive and effective catalysts for oxygen reduction reaction (ORR) has become one of the most important topics. Herein, we designed a novel MnCo2O4/N,S‐doped carbon nanotubes hybrid nanocomposite, which was synthesized via facile solvothermal and solution‐based oxidation‐precipitation process. After carefully investigated by Cyclic voltammetry (CV) and Rotating‐disc electrode (RDE) tests, the result indicated that benefiting from the doping N,S into carbon nanotubes provides superior enhancement of electrocatalytic activity.

Molybdenum nitride/nitrogen-doped multi-walled carbon nanotubes hybrid nanocomposites as novel electrochemical sensor for detection l-cysteine

In this work, we reported a novel, facile and effective strategy by using hydrothermal reaction and following high-temperature pyrolysis under the ammonia flow to fabricate the molybdenum nitride nanosheets/N-doped multi-walled carbon nanotubes (MoN/N-MWNTs) hybrid nanocomposite. MoN/N-MWNTs nanocomposite was characterized via X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and electrochemical methods. This nanocomposite exhibits excellent electrocatalytic oxidation of l-cysteine (l-CySH). An amperometric l-CySH sensor was constructed based on the MoN/N-MWNTs modified glassy carbon electrode. The as-prepared MoN/N-MWNTs nanocomposite has favourable conductivity, large surface area due to the MWNTs as supporter and highly exposed active sites of MoN. Moreover, the influence of different loading amounts of MoN was researched. The optimized MoN/N-MWNTs catalyst showed a wide detection range that was composed by two line segments (5μM– 0.79mM and 0.79mM–12.60mM), a sensitivity of 198.59nAμM−1cm−2 in the low concentration range, a rapidly response within 1.5s as well as good reproducibility and stability.

Progress and challenges of carbon nanotube membrane in water treatment

ABSTRACTThe potential of the carbon nanotube (CNT) membrane has been highly strengthened in water treatment during the last decade. According to works published up to now, the unique and excellent characteristics of CNT outperformed conventional polymer membranes. Such achievements of CNT membranes are greatly dependent on their fabrication methods. Further, the intrinsic properties of CNT could be a critical factor of applicability to membrane processes. This article provides an explicit and systematic review of the progress of CNT membranes addressing the current epidemic—whether (i) the CNT membranes could tackle current challenges in the pressure- or thermally driven membrane processes and (ii) CNT hybrid nanocomposite as a new generation of materials could complement current CNT-enhanced membrane.

Ultra-sensitive determination of epinephrine based on TiO2-Au nanoclusters supported on reduced graphene oxide and carbon nanotube hybrid nanocomposites

A highly efficient and sensitive electrochemical sensor for EP based on reduced graphene and multi-walled carbon nanotube hybrid nanocomposites loaded TiO2-Au nano-clusters modified glassy carbon electrode was developed. The surface nature and morphology of the nanocomposite film and the electrochemical properties of the sensor were characterized by Raman spectra, X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectra (EDX), Fourier transform infrared spectroscopy (FT-IR), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), respectively. Carbon nanomaterials were widely used in sensing due to its large electroactive surface area, fast electron transport and strong adsorption capacity. Meanwhile, TiO2-Au nano-clusters could accelerate the electron transfer, increase reactive site and extend electrochemical response window. The nanocomposite film could greatly enhance the response sensitivity and decrease the overpotential. The resulting sensor showed an excellent electrocatalytic activity toward EP. Under the optimum conditions (i.e. pH6.0, 0.1M PBS, preconcentration for 110s), Differential pulse voltammetry was employed to detect ultra-trace amounts of EP. The result of a wide linear range of 1.0–300nM and limited of detection 0.34nM (S/N=3) were obtained. The constructed sensor exhibited excellent accuracy and precision, the relative standard deviation (RSD) was less than 5%. The nanocomposite film sensor was successfully used to accurately detect the content of EP in practical samples, and the recoveries for the standards added are 97%–105%.

Flexible plane heater: Graphite and carbon nanotube hybrid nanocomposite

We report a facile method for fabricating a flexible plane heater on a plastic substrate using a graphite and carbon nanotube hybrid nanocomposite. To scale up to an industrial level, all the processes are applied in a conventional manner including three-roll calendar and screen printing. Bare graphite flakes are used as a main filler to increase the electrical conductivity of the nanocomposite. To preserve the high crystallinity of graphite, chemical treatments are excluded during the process. A small amount of amino-functionalized multi-walled carbon nanotubes (a-MWCNTs) (10wt%) are added not only to increase the mechanical strength of the plane heater, but also to improve the heat conduction in the nanocomposite. Therefore, while graphite nanocomposite film mostly peeled off after an adhesion test, a-MWCNT-graphite nanocomposite film adhered on the PET substrate without noticeable change. Furthermore, the fabricated plane heater shows the high performance, compared to that of a graphite nanocomposite, a carbon black/graphite nanocomposite, and Cu wire heaters. We demonstrate that our plane heater is applicable for heating seats of commercial vehicles as well as a flexible plane heater. It will be applied to numerous areas such as heating systems in electrical vehicle and household items for heating.

The preparation and electrochemical properties of MnO2/poly(3,4-ethylenedioxythiophene)/multiwalled carbon nanotubes hybrid nanocomposite and its application in a novel flexible micro-supercapacitor

In this work, a novel supercapacitor electrode material named MnO2/b-PEDOT/MWCNTs is synthesized by first preparing the PEDOT hollow spheres (b-PEDOT), and then anchoring the b-PEDOT on the surface of MWCNTs. At last, wrapping MnO2 nano-grains onto the surface of b-PEDOT and these composite spherical grains form a network structure with multiwalled carbon nanotubes (MWCNTs) after the coprecipitation process. Utilizing this hybrid material, a specific capacitance of 270 F g−1 at a current density of 0.3 A g−1 is achieved. A new flexible, low cost and easy fabricated micro-supercapacitor device by using MnO2/b-PEDOT/MWCNTs nanocomposite as electrode material is assemblied, which has a relatively rectangle in shape of standard cyclic voltammetry curves, indicating excellent supercapacitor behavior and a specific capacitance of 110 F g−1 at a current density of 2 A g−1 is achieved. The CV curves of the assemblied micro-supercapacitor under different bending states showed that there is no noticeable difference of electrochemical properties after being folded.

Zinc oxide–multiwalled carbon nanotubes hybrid nanocomposite based urea biosensor

An efficient matrix comprising a hybrid nanocomposite of zinc oxide (ZnO) and multiwalled carbon nanotubes (MWCNTs) has been synthesised on indium tin oxide coated glass slides (ITO/Glass) using a chemical route deposition technique for the realization of an efficient urea biosensor. Urease (Urs) was used as the specific enzyme for urea detection and was physically immobilized over the surface of the hybrid nanocomposite matrix based (ZnO-MWCNT/ITO) electrode. The fabricated Urs/ZnO-MWCNT/ITO bioelectrode was characterized using electrochemical impedance spectroscopy (EIS) and cyclic voltammetric (CV) techniques. The nanocomposite based bioelectrode i.e. Urs/ZnO-MWCNT/ITO exhibits enhanced biosensing response characteristics as compared to that of the bare ZnO based (Urs/ZnO/ITO) bioelectrode. The prepared bioelectrode (Urs/ZnO-MWCNT/ITO) exhibits a very high sensitivity of about 43.02 μA mM-1 cm-2 and a long shelf-life of more than 4 months (>16 weeks). The low Michaelis-Menten parameter (Km) value, only 0.85 mM, indicates high affinity of the immobilized urease on the surface of hybrid nanocomposite matrix towards its analyte (urea). The obtained results in the present study are encouraging and will pave the way towards the realization of an efficient urea biosensor.

Cellulose–titanium dioxide–multiwalled carbon nanotube hybrid nanocomposite and its ammonia gas sensing properties at room temperature

Abstract A titanium dioxide (TiO2)–multiwall carbon nanotube (MWCNT) nanocomposite was synthesized by hydrothermal process. X-ray diffractometry, transmittance electron microscopy observation revealed that the nanocomposite has high nanocrystal structure. After blended with cellulose, a cellulose–TiO2–MWCNT hybrid nanocomposite was made and applied to a room temperature ammonia (NH3) gas sensor. The cellulose–TiO2–MWCNT hybrid nanocomposite exhibited much higher response and faster recovery for NH3 gas when the gas concentration changed from 50 ppm to 500 ppm. The gas sensing mechanism of the hybrid nanocomposite gas sensor is also discussed. This hybrid gas sensor is flexible and cheap with good sensitivity and repeatability.

Processing and thermal/mechanical studies of unsaturated polyester toughened epoxy composites filled with amine functionalized carbon nanotubes

The intercrosslinking networks of unsaturated polyester (UP) toughened epoxy and amine modified multiwalled carbon nanotube hybrid nanocomposites have been developed. Ultrasonication and ball milling were carried out for effective dispersion of the amine functionalized multiwalled carbon nanotubes within the resin. A mixture of concentrated H2SO4/HNO3 was used to oxidize the carbon nanotubes and further chemical functionalization was carried out by using ethylene diamine. The pristine and amine functionalized nanotubes were examined by FT-IR, TGA, XRD and Raman spectroscopy to characterize the attached functional groups and the defects caused by the chemical modification. The epoxy resin was toughened with 5 and 10% (by wt) of unsaturated polyester using benzoyl peroxide as radical initiator and 4, 4'diaminodiphenylmethane (DDM) as curing agent. Epoxy and Unsaturated polyester toughened epoxy systems were further modified with 0.1, 0.3 and 0.5% (by wt) of amine modified multi walled carbon nanotube (NH2-CH2-CH2-NH-CO-MWCNT). The modified MWCNT filled hybrid UP-epoxy matrices developed in the form of casting were characterized for their mechanical, thermal properties and water absorption capacity as per ASTM standards. Thermal behavior of the matrices was characterized by differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA). Significant improvement in the flexural and tensile properties were observed on the neat epoxy and UP-epoxy blends according to the percentage content of amine modified MWCNT particles. The water absorption behavior decreases with UP toughening and increases with concentration of amine modified MWCNT on the epoxy and UP-epoxy matrix. The homogeneous morphologies of the UP toughened epoxy and UP toughened epoxy-nanocomposite hybrid systems were ascertained from scanning electron microscope (SEM).

Solar exfoliated graphene–carbon nanotube hybrid nano composites as efficient catalyst supports for proton exchange membrane fuel cells

Ultra thin graphene–multi walled carbon nanotube composites prepared by a solar exfoliation technique have been explored as catalyst supports for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFC). Pt nanoparticles were dispersed on a solar exfoliated graphene-functionalized multi walled carbon nanotube (sG-fMWNT) hybrid nanocomposite, which exhibits higher electrocatalytic activity for ORR than Pt dispersed functionalized solar graphene (f-sG) catalyst support. The single cell PEMFC measurements give maximum power densities of 355 mW cm−2 and 675 mW cm−2 with sG and sG-f MWNT respectively. The improved performance in the power density with the sG-f MWNT fuel cell can be ascribed to the synergistic effect of 1D MWNT and 2D graphene in sG-f MWNT as well as its high electrochemical surface area. The inclusion of MWNT bridges the defects for electron transfer besides increasing the basal spacing between graphene sheets. The good performance and possibility of high throughput production of sG-f MWNT makes this material a promising catalyst support for PEMFC.

Carrier transport mechanisms of bistable memory devices fabricated utilizing core–shellCdSe/ZnSe quantum-dot/multi-walled carbon nanotube hybrid nanocomposites

Transmission electron microscopy images showed that conjugation between single core–shellCdSe/ZnSe quantum dots (QDs) and oxidized multi-walled carbon nanotubes(MWCNTs) was achieved through the complexation reaction. Current–voltage(I–V) measurements on Al/CdSe:MWCNT conjugated nanocomposite/indium–tin-oxide devicesat 300 K showed that the on/off ratio of the current bistability was as large as about104, which was significantly increased due to an enhancement of the carriertransfer efficiency between the CdSe/ZnSe QDs and the MWCNTs. Carriertransport mechanisms of the bistable memory devices fabricated utilizingCdSe/ZnSe QD/MWCNT hybrid nanocomposite are described on the basis of theI–V results.