Diameter Of Multi-walled Carbon Nanotubes Research Articles

Impact of Atomic Vacancy Defects on Vibrational Characteristics of Chiral MWCNT for Viruses/Bacteria

In this study the authors investigated the vibrations performance of chiral multi-walled carbon nanotubes (MWCNTs). They examined chiral MWCNTs with attached bacteria positioned at both the tip and middle sections of the nanotubes. The main goal of this research was to create a sensor with the ability to detect and distinguish bacteria or viruses that could potentially adhere to the surfaces of chiral MWCNTs. The authors considered two boundary conditions, fixed-fixed and fixed -free for the chiral MWCNT. They utilized a molecular structural mechanics approach. In this approach the vibrational responses of chiral MWCNT-based nano-biosensors with different diameters of the chiral MWCNTs were examined. The study’s objective was to fill research gaps by introducing an innovative approach for detecting defects in chiral MWCNTs through vibrational analysis. They simulated 432 MWCNT samples to investigate the vibrational performance of defective chiral MWCNTs. The results suggested that the first mode of the vibrational frequency of the chiral MWCNT is particularly significant for sensing applications. It was observed that as the percentage of vacancy defects increased, the natural frequency decreased for both boundary conditions.

Effect of multi-walled carbon nanotubes diameter in electrochemical activity of lithium iron phosphate

Multi-walled carbon nanotube (MWCNT) is an attractive conductive carbon material for lithium-ion batteries (LIB). However, without a comprehensive understanding of the link between MWCNT diameter and polarization in an active material, it remains challenging to use MWCNT in high energy density batteries. Herein, we report a comparative cyclic voltammetry (CV) study of MWCNT with different diameters for lithium iron phosphate (LFP) electrochemical activity. The discrete smaller outer diameter MWCNT (<8 nm) significantly decreases the polarization and increases LFP electrochemical activity. Our study presents a simple and straightforward method to choose MWCNT for LIB.

Hydrothermal impact of multiwall carbon nanotube diameter in a conventional square cavity

This study aimed to computationally examine the effect of the average diameter of multiwall carbon nanotubes (MWCNTs) on the hydrothermal properties of a square cavity. A conventional square cavity filled with MWCNT–water was used for the experiment. The left and right walls of the cavity are maintained as hot and cold respectively, whereas the top and bottom walls were assumed to be adiabatic. Mathematical models were developed using the Navier–Stokes equations by applying the thermophysical properties of the MWCNT–water nanofluid. A newly proposed correlation between the effective thermal conductivity and the diameter of carbon nanotube was utilized to analyze the impact of the average diameter on the natural convection of nanofluid inside the cavity. The governing equations were non-dimensionalized using suitable variables and then solved using the Galerkin finite element technique. The combined effects of the Rayleigh number (103<Ra<106) and the average diameter of the MWCNTs (10 nm to 30 nm) on the streamlines, isolines, velocity, local Nusselt number, and mean Nusselt number were examined in detail. It is found that the flow and heat transfer rate inside the cavity can be effectively controlled by increasing the average diameter of MWCNTs at higher Rayleigh numbers compared to lower Rayleigh number. A larger MWCNT diameter dominated the impact of the buoyancy force inside the square cavity.

Effect of Diameter of Carbon Nanotubes in Nanocomposite Membrane for Methyl Orange Dye Removal

It is worth noticing that structure of nanomaterials affects the membrane performance, however, the effect of diameter of multiwalled carbon nanotubes (MWCNTs) has not been discussed in the past. This research aims to investigate the effect of diameter of MWCNTs on the performance of graphene oxide (GO)/ MWCNTs nanocomposite membrane for methyl orange dye removal. MWCNTs with different diameters (12-15 nm, 30-50 nm) with the same length (&lt; 10 µm) are used to synthesize the nanocomposite membrane. The characteristics of the synthesized nanocomposite membrane were determined by surface hydrophilicity, pore size and porosity, zeta potential, and Fourier-transfer infrared (FTIR) spectroscopy. Besides, the membrane performance was evaluated by the water permeability test, dye rejection test, and antifouling test. The result showed that pure MWCNTs (30-50 nm) nanocomposite membrane (M2b) has the best performance among the synthesized membrane. The dye rejection of M2b membrane reached 86.77% and the normalized flux was approximately 0.82. Lower dye rejection (83.37%) and normalized flux (0.76) were attained by M2a membrane with smaller diameter MWCNTs (12-15 nm). This was due to M2b membrane having a smaller pore size (0.032 nm), which helped reduce the tendency of dye to pass through the membrane. Besides, M2b membrane has a more negative surface charge (-10.93 mV) that produces larger repulsion force, resulting in more dye being rejected. In conclusion, the performance of the synthesized nanocomposite membrane particularly antifouling properties can be enhanced with the addition of MWCNTs with larger diameter.

Evaluation of the effect of diameter of multi-walled carbon nanotube on the tensile strength using sonication-induced fragmentation

Ultrasonication is a simple way to cut carbon nanotubes in suspension. The length of fragmented carbon nanotubes is made shorter by iterating ultrasonication but approaches a critical aspect ratio. The critical aspect ratio is determined by the tensile strength of the carbon nanotube, the viscosity of the solvent, and physical properties of the cavitation bubbles produced by ultrasonication. Thus, it is possible to evaluate the tensile strength of carbon nanotubes from the critical aspect ratio. In this study, the tensile strengths of multi-walled carbon nanotubes with different diameters were evaluated using sonication-induced fragmentation. The results confirmed the strong dependency of tensile strength on diameter.

Oxidative Stress in Long-Term Exposure to Multi-Walled Carbon Nanotubes in Male Rats

Multi-walled carbon nanotubes (MWCNTs) serve as nanoparticles due to their size, and for that reason, when in contact with the biological system, they can have toxic effects. One of the main mechanisms responsible for nanotoxicity is oxidative stress resulting from the production of intracellular reactive oxygen species (ROS). Therefore, oxidative stress biomarkers are important tools for assessing MWCNTs toxicity. The aim of this study was to evaluate the oxidative stress of multi-walled carbon nanotubes in male rats. Our animal model studies of MWCNTs (diameter ~15-30 nm, length ~15-20 μm) include measurement of oxidative stress parameters in the body fluid and tissues of animals after long-term exposure. Rattus Norvegicus/Wistar male rats were administrated a single injection to the knee joint at three concentrations: 0.03 mg/mL, 0.25 mg/mL, and 0.5 mg/mL. The rats were euthanized 12 and 18 months post-exposure by drawing blood from the heart, and their liver and kidney tissues were removed. To evaluate toxicity, the enzymatic activity of total protein (TP), reduced glutathione (GSH), glutathione S-transferase (GST), thiobarbituric acid reactive substances (TBARS), Trolox equivalent antioxidant capacity (TEAC), nitric oxide (NO), and catalase (CAT) was measured and histopathological examination was conducted. Results in rat livers showed that TEAC level was decreased in rats receiving nanotubes at higher concentrations. Results in kidneys report that the level of NO showed higher concentration after long exposure, and results in animal serums showed lower levels of GSH in rats exposed to nanotubes at higher concentrations. The 18-month exposure also resulted in a statistically significant increase in GST activity in the group of rats exposed to nanotubes at higher concentrations compared to animals receiving MWCNTs at lower concentrations and compared to the control group. Therefore, an analysis of oxidative stress parameters can be a key indicator of the toxic potential of multi-walled carbon nanotubes.

Effect of multiwalled carbon nanotube size on electrical properties of cement mortar composites

Cement mortars (CM) containing different contents and sizes of multiwalled carbon nanotubes (MWCNTs) were prepared using surfactants in combination with ultrasonic dispersion. The effects of the content, diameter and length of MWCNTs on the electrical conductivity of cement mortar and the self-inductive piezoresistive rate under single and cyclic loading were studied using the four-electrode method. The results show that the conductive percolation thresholds of CMs containing MWCNTs with different length–diameter ratios occur at an approximate MWCNT content of 0.1 wt%. The electrical conductivity of cement mortars with MWCNT diameters of 10–20 nm was the largest for a content of 0.1 wt%, and the values were 112% and 128.3% of the conductivity of the MWCNTs/CM with diameters of 20–40 nm and 40–60 nm, respectively. In addition, the fractional change in resistivity of the cement mortar specimens varied most significantly at a content of 0.75 wt% of MWCNTs; the fractional change in resistivity reached 14.27%. Adding small-diameter MWCNTs to cement mortar can maximise the sensitivity of electrical resistance of cement mortar to compressive stress.

A study on development of silicone rubber with conductive carbon, polyaniline, MWCNT composite for EMI shielding

The multiwall carbon nanotubes (MWCNTs) were grown by CVD method and using Ni impregnated zeolite as a substrate. The prepared MWCNT diameter varied from 10 to 60 nm and length in few microns. The silicone rubber (SR) was mixed well with conductive carbon, Polyaniline (PANI) and MWCNTs in two roll mill. The prepared silicone rubber materials were fabricated in the form of sheets with dimensions of 200 mm × 200 mm × 2 mm by using compression molding technique. The prepared sheets were subjected for EMI shielding efficiency measurements at low frequency (&lt; 1.5 GHz) and high frequency range from 1 GHz to 18 GHz. At high frequency the shielding effectiveness of the Conducting Silicone Rubber and Conductive silicone rubber with MWCNT was found to be 24 dB and 48 dB. The volume resistivity measurements were also carried for all the prepared silicone rubber sheets, the results reveals that SR + MWCNT, CSR + MWCNT composites shows volume resistivity 4032 and 20.7 Ω.cm respectively. This confirms the conductivity of CSR + MWCNT is enough to exhibit good Shielding Effectiveness.

Microwave absorption performance of MWCNTS derived from plant based oil

The carbon nano structure (CNS) have excellent dielectric properties and hence shows better microwaveabsorbingperformance. The economically obtained CNS are efficient microwave absorbing materials (MAMs) demonstrate a big potential in industrial and defense application. The synthesis of CNS from Plant based precursors has become one of the newest approach in the field ofmicrowaveabsorption due to its economical, immense availability and sustainability. Chemical Vapour deposition (CVD) is most utilized method to synthesize Multiwall Carbon Nano Tubes (MWCNTs) using plant based oil due to its easy to control experiment condition, economical, controllable diameters and better yield compare to others methods.Plant-based precursors i.e., Olive oil was used as source of carbon to obtained MWCNTs over Ni-Co catalyst in inert atmosphere of Hydrogen gas. Acid treated MWCNTs were characterized using XRD, FEG-SEM, EDAX, HR-TEM. The average diameter and length of MWCNTs are 48 nm and 736 nm, respectively. MWCNTs/Acrylic composite with 9 wt% and 3.8 mm thickness, shows an optimal Reflection loss (RL) value of −44.0 dB at 10.9 GHz. The effective absorption (RL ≤ -20 dB) has a bandwidth of 10.14–11.59 GHz.

Tailoring Fe2O3–Al2O3 catalyst structure and activity via hydrothermal synthesis for carbon nanotubes and hydrogen production from polyolefin plastics

Fe2O3–Al2O3 catalysts applied for conversion of polyolefin plastic waste into multi-walled carbon nanotubes (MWCNTs) and H2 are typically produced by impregnation, co-precipitation or sol-gel synthesis at atmospheric pressure and temperatures below 100 °C. This study utilized hydrothermal conditions and established the role of precipitating agents (urea, N-methylurea and N,N′-dimethylurea) on properties and catalytic activity of Fe2O3–Al2O3 catalysts (Fe-u, Fe-mu and Fe-dmu, respectively). The precipitating agent played a key role in tailoring the properties, such as crystallization degree, surface area and reducibility. The precipitating agents influenced the yield and outer diameters of MWCNTs but did not affect graphitization degree. Among the synthesized catalysts, Fe-u had the largest surface area and preferential formation of the highly reducible α-Fe2O3 crystalline phase. As a result, Fe-u had the highest activity during conversion of pyrolysis gas from low-density polyethylene (LDPE) into MWCNTs, yielding 0.91 g·g−1-catalyst MWCNTs at 800 °C as compared to 0.42 and 0.14 g·g−1-catalyst using Fe-dmu and Fe-mu, respectively. Fe-dmu favored the growth of MWCNTs with smaller outer diameters. Fe-u demonstrated high efficiency during operation using a continuous flow of pyrolysis gas from a mixture of polyolefins (70 wt% polypropylene, 6 wt% LDPE and 24 wt% high density polyethylene) producing 4.28 g·g−1-catalyst MWCNTs at 3.2% plastic conversion efficiency and a stable H2 flow for 155 min (25–32 vol%). The obtained data demonstrate that the selection of an appropriate precipitating agent for hydrothermal synthesis allows for the production of highly active Fe2O3–Al2O3 catalysts for the upcycling of polyolefin plastic waste into MWCNTs and H2.

The potential of white and soft-rot fungi for biodegradation of multi-walled carbon nanotubes (MWCNTs): characterization and enzyme analysis

ABSTRACT Multi-walled carbon nanotubes (MWCNTs) have significant environmental concerns for soil, water and ecosystems. Since their harmful effects on human health, including respiratory disease, they are considered dangerous substances. Thus, it is required to discover a constructive solution to decrease of MWCNT toxicity. Due to their high degradability, white rot and soft rot fungi have been used in the biodegradation of various pollutants. In this study, we evaluated the ability of native Iranian white and soft rot fungi to degrade MWCNTs mainly by means of dynamic light scattering (DLS) and surface charge measurement. In this regard, growth kinetics, CO2 and protein production, size, surface charge and pH change were measured. Continuous Raman spectroscopy, scanning electron microscope (SEM) and transmission electron microscope (TEM) imaging were carried out to detect the process of degradation. The results showed that the morphology, arrangement, size and diameter of MWCNTs were modified due to fungal degradation. The cytotoxicity of treated MWCNTs was determined by the MTT test. The results indicated that native Iranian white and soft rot fungi have a significant ability for degradation of MWCNTs. Furthermore, it could be concluded that fungal treatment could reduce the toxicity of MWCNTs and the best result was achieved in 500 ppm MWCNTs for Trichoderma sp. The activities of oxidative enzymes such as laccase, manganese peroxidase (MnP) and lignin peroxidase (LiP) were measured to determine the mechanism of degradation. Enzyme assays have suggested that these oxidising enzymes especially laccase might play a key role in the degradation of MWCNTs in white rot and soft rot fungi. The overall results confirmed the reproductive ability of Trichoderma sp. WF29 as a soft rot and two white rot fungi Irpex lacteus WF36 and Trametes versicolor to degrade MWCNT.

Study of rheological properties of carbon nanotube-reinforced ultrafine cement grouting materials

In this study, three different diameters of multi-walled carbon nanotubes (MWCNTs) dispersed by polyvinyl pyrrolidone (PVP) were used to reinforce superfine cement grouting materials. The effect of MWCNTs and PVP on the rheological properties of grouting material were accordingly studied. It was found that the yield stress (τ0) and plastic viscosity (η) decreased slightly when PVP content was low and increased when PVP content increased. The effect of MWCNT diameter on τ0was not found to be clear but was more significant on η. The smaller the MWCNT diameter, the quicker η increased. It was also found that the thixotropic ring area increased as the MWCNT content increased. The addition of PVP and MWCNTs caused an increase in the number of entanglement points in different scales, which was the main reason for the viscosity and thixotropy increase. Therefore, the rheological properties of superfine cement grouting material should be adjusted when MWCNTs are added as a reinforcing component. Owing to the wrapping of PVP on cement particles, which isolates the contacting part between water and cement particles, it slows down the hydration rate of cement and thus slows down the fluidity loss of the slurry.

Synthesis and characterization of catalytic CVD growth pristine and functionalized MWCNT

The catalyzed CVD method is considered significant for the production of low cost and high yield carbon nanostructures. In this study, multiwall carbon nanotubes (MWCNTs) were synthesized using a facile and efficient way with the modified CVD method, using Co nanoparticles as the metallic catalysis for MWCNT growth, in a distinct temperature range of 650–750 °C. The structural and magnetic properties of pristine and functionalized MWCNT (p-MWCNT and f-MWCNT) are investigated in the temperature range of 10–300 K. The phase structure of all MWCNT samples was analyzed using various characterization techniques, namely, x-ray diffraction, Raman, and x-ray photoelectron spectroscopy. Scanning electron microscopy and particle size analysis suggested that the diameter of MWCNTs increases with a rise in the growth temperature, but the nanotube density decreases at 750 °C. Temperature-dependent magnetization studies of the p-MWCNT and f-MWCNT samples were investigated using a quantum design physical property measurement system-vibrating sample magnetometer mode. The magnetic properties and the effect of the growth temperature and acid functionalization on the morphology of MWCNT were also investigated. The results revealed that the diamagnetism effect of the graphitic nanotubes is dominating for p-MWCNT, and it reduces for f-MWCNT. A possible explanation for this feature is discussed in detail in the later part of this article. It may be considered that this study, which emerged with different growth temperatures of MWCNTs using a facile method for gaining control over magnetic properties, can be fundamental for further consideration of magnetic MWCNTs for various potential applications.

Outer diameter Curvature effects in Multi-Walled carbon nanotubes on the twistron energy harvester

We describe an experimental and computational study of increased electrical double layer capacitance (EDLC) changes and improved harvesting performances in multi-walled carbon nanotube (MWCNT) yarn-based energy harvesters using smaller-diameter MWCNTs. Twisted MWCNT yarn-based energy harvesters convert tensile mechanical energy into electrical energy by utilizing changes in the EDLC on the surface of MWCNTs. The correlation of the variance in EDLC and open circuit voltage (OCV) of the coiled MWCNT yarn was investigated under the mechanical stretch applied to the twistron energy harvester, and both OCV and capacitance increased as the MWCNT diameter decreased. We performed molecular dynamics (MD) simulations to elucidate the mechanisms of the increasing EDLC and OCV of twistron energy harvesters, which were verified by experiment. The computational results elucidate the relationship between the decrease in MWCNT diameters and the increasing number density of interstitial spaces between multi-walled MWCNTs. The decrease in the total surface area of the interstitial spaces is an important factor in the capacitance change of the twistron energy harvester under longitudinal stretching. Such novel findings are a foundation for the development of a twistron harvester with significantly improved energy harvesting performance.

The effect of MWCNTs with different diameters on the interface properties of Ti/CFRP fiber metal laminates

Fiber-metal laminates (FMLs) consist of alternating thin layers of metal and fiber-polymer composite and are characterized by a relatively weak interface. In this paper, to address the needed improvement in the strength of the metal-resin interface, we apply molecular dynamics (MD) simulations in the design of an interface model of titanium-polyimide (Ti/PI) in which multi-walled carbon nanotubes (MWCNTs) of diameters ranging from 2 nm to 20 nm are added to PI resin to enhance the interface mechanical properties of the obtained Ti/carbon fiber-reinforced polyimide (Ti/CFRP) FMLs. As a result, these mechanical properties can be significantly improved by adding MWCNTs of different diameters to a polymer matrix. The van der Waals energy and the total energy of the system linearly increased with increasing diameter of the MWCNTs. Furthermore, the interfacial interaction energy decreased with increasing MWCNT diameter to a minimum, then increased and finally stabilized, which implied that the improvement of the interface properties followed the same trend. Notably, at an average MWCNT diameter of 8 nm, the interface fracture energy as an indication of interface mechanical performance is increased by nearly 180% compared to the material without MWCNTs.

Synthesis and formation mechanism of novel double-thick-walled silicon carbide nanotubes from multiwalled carbon nanotubes

In this study, double-thick-walled (DTW) silicon carbide (SiC) nanotubes, the walls of which comprise connected disordered polycrystalline nanograins, were successfully synthesized for the first time via the reaction of multiwalled carbon nanotubes (MWCNTs) with Si powder. DTW SiC nanotubes are expected to exhibit novel properties unlike other SiC nanomaterials, owing to their intriguing geometries. The DTW SiC nanotubes had a wall thickness exceeding 20 nm, regardless of the external diameter, as indicated by transmission electron microscopy results. The DTW SiC nanotubes with a spacing of above 30 nm between the outer and inner nanotubes exhibited perfect double-walled structures. The inner and outer nanotubes were not connected in any region. When all the carbon was transformed into SiC, the volume of carbon increased to 2.2 times the initial value. These results reveal that DTW SiC nanotubes with perfect structures cannot be synthesized without an MWCNT wall thickness of at least 50 nm. Several types of DTW SiC nanotubes with different morphologies, such as diameter, end structure, and distance between the inner and outer nanotubes, were synthesized. The morphology of DTW SiC nanotubes can be controlled by changing the wall thickness and/or diameter of the original MWCNTs and the reaction conditions.

Influence of the diameter of multi-walled carbon nanotubes on the electrochromic performance of NiO thin films

This work presents the influence of functionalized multi-walled carbon nanotubes (MWCNTs) with different diameter on the electrochromic performance of compact NiO films deposited by electrostatic spraying. MWCNTs did not noticeable modify the structure and morphology of NiO films, although they tended to adsorb larger amounts of OH and O. Spectroelectrochemical measurements show that MWCNTs with a diameter of 15–25 nm are preeminent to enhance the charge-transfer kinetics (36.1%), coloration efficiency (17.3%), reversibility (12.5%) and cycling durability (66.6%) of NiO films.

Size dependent conduction characteristics of catalyst-multi-walled carbon nanotube junction

Multi-walled carbon nanotubes (MWCNTs) grown by chemical vapor deposition retain the residual catalyst particles from which the growth occurred, which are considered a detriment to MWCNTs’ performance, especially electrical conductivity. The first direct measurements have been made of the electrical transport through the catalyst cap into the MWCNT using nanoscale 2-point-probe to determine the effects of the catalyst particle’s size and the diameter ratio with its associated MWCNT on the electrical transport through the catalyst cap as compared to the inherent conductivity of the MWCNT. The MWCNT diameter is independent of the catalyst size, but the ratio of the catalyst cap diameter to MWCNT diameter (DC/DNT) determines the conduction mechanism. Where DC/DNT is greater than 1 the resulting I–V curve is near ohmic, and the conduction through the catalyst (RC+NT) approaches that of the MWCNT (RNT); however, when the DC/DNT > RNT. The experimental results are discussed in relation to current crowding at the interface between catalyst and nanotube due to an increased electric field.

Effect of multiwalled carbon nanotube diameter on mechanical behavior and fracture toughness of epoxy nanocomposites

Epoxy nanocomposites reinforced by multiwalled carbon nanotubes (MWCNT) with different diameters were prepared. The effect of MWCNT diameter on mechanical and fracture properties of epoxy nanocomposites were investigated. The results show that the MWCNT diameter has an important influence on its dispersion performance. As the MWCNT diameter increases, the dispersion performance becomes better. The reinforcing effect of MWCNTs on epoxy resins (EP) is affected by the combination of factors including the diameter and the additive amount of MWCNTs as well as its dispersion. At low additive amount of MWCNTs (≤0.3 wt%), the reinforcing effect of MWCNTs with smaller diameter is better. However, as the additive amount of MWCNTs increases (≥0.5 wt%), the reinforcing effect of MWCNTs with larger diameters becomes more significant. MWCNTs with diameter of 25 nm (MWCNT-25) have the best reinforcing effect when the additive amount is 0.5 wt%, and the tensile strength and elastic modulus of the MWCNT-25/EP composites are increased by 11.5% and 8.3% than those of EP, respectively. The fracture toughness of the composites shows a tendency to increase first and then decrease with the increase of MWCNT diameter. The main reason of this tendency is that the main failure mode of MWCNTs gradually changes from fracture to pull-out with the increase of MWCNT diameter. The optimal MWCNT diameter is 25 nm, reaching the best toughening effect (KIC and GIC are increased by 38.8% and 80.9% than those of EP, respectively) at the additive amount of 0.7 wt%.

Direct Electron Transfer Between Single-Walled Carbon Nanotube and Fructose Dehydrogenase

In this paper, we report the direct electron transfer (DET) reaction between debundled single-walled carbon nanotubes (SWCNTs) and the enzyme flavin adenine dinucleotide (FAD)-dependent fructose dehydrogenase (FDH). An anionic surfactant, sodium cholate (SC), was used to debundle the SWCNTs and disperse them in an aqueous solution, and the experimental conditions were optimized. The DET electrode, FDH/SWCNT-SC, was fabricated by the layer-by-layer drop-casting technique. Cyclic voltammetry experiments were conducted, and the experimental results revealed the presence of a high level of fructose concentration-dependent current (FDC). In the control experiment, FDC was not observed with either multi-walled carbon nanotubes (MWCNTs) or graphene flakes. The reported dimension of the FDH molecule is ~7 nm, which is larger than the diameter of an individual SWCNT (1 nm) but smaller than the diameter of an individual MWCNT (10 nm) and the dimensions of a graphene flake (~100 nm square). Only individual SWCNTs can reside in close proximity (within the distance for DET) of the cofactors FAD and heme c, both of which remain deeply embedded within the protein shell. The FDH/SWCNT-SC electrode had a sensitivity of 27 μA mM <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> , a linear dynamic range of 1.4-18.5 mM, and a detection limit of 2.1 μM. The electrode, combined with the enzyme invertase (IVT), can detect the total concentration of fructose and sucrose in samples (using the IVT/FDH/SWCNT-SC electrode). Therefore, fructose and sucrose can be separately quantified when both FDH/SWCNT-SC and IVT/FDH/SWCNT-SC electrodes are used. The amounts of fructose and sucrose in real food samples (100% fruit juice in the present case) determined using these electrodes agreed well with the amounts obtained from high-performance liquid chromatography (HPLC) experiments.