Graphene oxide （GO）-multiwalled carbon nanotube （MWCNT） composite was synthesized and characterized by X-ray diffraction, atomic force microscopy, scanning electron microscopy, micro Raman, Fourier transform infra...Graphene oxide （GO）-multiwalled carbon nanotube （MWCNT） composite was synthesized and characterized by X-ray diffraction, atomic force microscopy, scanning electron microscopy, micro Raman, Fourier transform infrared and ultraviolet-visible near infrared spectroscopy techniques. Spectral characteris- tics of cladding modified fiber optic gas sensors were studied for various concentrations of ammonia, ethanol and methanol at 27 ℃. Thickness of the gas sensing layer was controlled by varying the concentration of composite in ethanol medium （0.5 and 1 mg/mL） for three times dipping process. The O.S mg/ mL concentrated GO-MWCNT coated sensor showed 1.20, 1.40 and 1.15 times higher sensitivity than the GO coated sensor for ammonia, ethanol and methanol vapors, respectively. Furthermore, it exhibited 1.50, 1.80 and 1.80 times better sensitivity than 1 mg/mL concentrated GO-MWCNT coated sensor for ammonia, ethanol and methanol vapors, respectively. The presence of functional groups in GO increased the sen- sitivity. This is mainly attributed to the effective electron charge transfer between the composite materials and analytes.展开更多
Copper has been deposited on the surface of multiwailed carbon nanombes （MWNTs） and inside MWNTs by electroless deposition. The as-prepared Cu-MWNT composite materials have been characterized by X-ray diffractometer...Copper has been deposited on the surface of multiwailed carbon nanombes （MWNTs） and inside MWNTs by electroless deposition. The as-prepared Cu-MWNT composite materials have been characterized by X-ray diffractometer （XRD）, transmission electron microscopy （TEM）, and electrochemical measurement. XRD analyses showed that Cu was a face-centered cubic （fcc） structure. The average size of Cu was calculated by Scherrer＇s formula from XRD data, and it was 11 nm. TEM revealed that Cu grains on the surface of MWNTs were uniform with the sizes of about 30-60 nm. The electrochemical measurement indicated that Cu-MWNT composite materials possessed fine electron conductivity.展开更多
Efficient separation and transfer of photogenerated electron/hole as well as enhanced visible light absorption play essential roles in photocatalytic reactions. To promote the photocatalytic reduction of Cr（VI）, a t...Efficient separation and transfer of photogenerated electron/hole as well as enhanced visible light absorption play essential roles in photocatalytic reactions. To promote the photocatalytic reduction of Cr（VI）, a toxic heavy metal ion, multiwalled carbon nanotube （MWCNT） was introduced as an electron acceptor into NH2-MIL-68（In）. This led to the growth of a willow leaf-like metal-organic framework （MOF） on an MWCNT backbone forming MWCNT/NH2-MIL-68（In） （PL-1）, which showed a highly efficient transfer of photogenerated carriers. Moreover, MWCNT incorporation introduced more mesopores for Cr（VI） diffusion and enhanced the visible light adsorption without lowering the conduction band position. As a result, the photocatalytic kinetic constant of PL-1 was found to be almost three times higher than that of the parent NH2-MIL-68（In）. Thus, growing MOFs on MWCNTs provides a facile and promising solution for effective remediation of environmental pollution by utilizing solar energy. This work provides the first example of using MWCNT/MOF composites for photocatalytic reactions.展开更多
The present study focuses on the thermal response of carbon fiber-reinforced phenolic composites, where the matrix has been modified with different reinforcements. Two types of materials, multiwalled carbon nanotubes ...The present study focuses on the thermal response of carbon fiber-reinforced phenolic composites, where the matrix has been modified with different reinforcements. Two types of materials, multiwalled carbon nanotubes and zirconium diboride （ZrB2）, were used in a new design of mixture to produce the heat- resistant ablative composite system. The CNT/ZrB2/carbon/phenolic nanocomposite （Z/NT-CR） system corresponding to CNT/carbon/phenolic nanocomposite （NT-CR） showed a reasonable decrease in mass loss and the ablation rate as compared to carbon/phenolic composite （CR）. However, substantial drop in two factors was found for Z/NT-CR as compared to carbon/phenolic and NT-CR. Ablation mechanisms for all three composites were investigated by thermal gravimetric analysis in conjunction with micro- structural studies using a field emission scanning electron microscope. The microstructural studies revealed that CNTs acted as an ablation resistant phase for protection against 2000 ℃, and the conversion from ZrB2 to ZrO2 played an important role as an insulator in the performance of char layer in the ablation resistance.展开更多
The effects of three types of electrically-inert fillers, calcium carbonate （CaCO_3）, talc and glass fiber （GF）, on electrical resistivity, crystallization behavior and dynamic mechanical properties of poly（m-xyl...The effects of three types of electrically-inert fillers, calcium carbonate （CaCO_3）, talc and glass fiber （GF）, on electrical resistivity, crystallization behavior and dynamic mechanical properties of poly（m-xylene adipamide） （MXD6）/multiwalled carbon nanotube （MWCNT） composites are investigated. The electrical resistivity of MXD6/MWCNT composites is significantly reduced with the addition of inert fillers due to the volume-exclusion effect that leads to increased effective concentration of MWCNTs in MXD6 matrix and also due to improved MWCNT dispersion. The crystallization temperature of MXD6 increases with the addition of MWCNTs, indicating that MWCNTs can act as nucleating agent and induce crystallization of MXD6. The incorporation of inert fillers has no further effect on crystallization behavior of MXD6, but significantly improves the storage modulus of MXD6/MWCNT composite, demonstrating that CaCO_3, talc and GF filled MXD6/MWCNT composites are very promising materials with not only improved electrical property but also excellent mechanical properties.展开更多
This paper described a new method for the trace determination of fenpropathrin, cyhalothrin and deltamethrin using multiwalled carbon nanotubes （MWCNTs） cartridge. Important parameters, such as the sample pH, eluent...This paper described a new method for the trace determination of fenpropathrin, cyhalothrin and deltamethrin using multiwalled carbon nanotubes （MWCNTs） cartridge. Important parameters, such as the sample pH, eluent and its volume, sample flow rate and sample volume were investigated in detail. The linear ranges, the detection limits, and precisions （R.S.D.） were in the range of 0.1- 40 μg L^-11, 1.34.3 ng L^-1 and 2.3-2.8%, respectively. The performance of the proposed method was validated with real water samples, and the spiked recoveries were in the range of 91.7-117.8%, respectively. The experimental results demonstrated that the proposed method was an excellent alternative for the routine analysis of such pollutants in environmental samples. 2007 Qing Xiang Zhou. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
In this paper the multiwalled carbon nanotubes （MWNTs） were synthesized by a chemical vapour deposition and the SEM graph shows that the sample has good construction. The micro-Raman spectrum shows the characteristi...In this paper the multiwalled carbon nanotubes （MWNTs） were synthesized by a chemical vapour deposition and the SEM graph shows that the sample has good construction. The micro-Raman spectrum shows the characteristic line of the MWNTs and an additional line produced by the defects on the outer surface of MWNTs. The photoluminescence （PL） spectra observed experimentally are variable under different excitation wavelengths and the strong excitation wavelength dependence of luminescence indicates a distribution of emitters which include electron π in excited states and the Van Hove singularities. The absorption spectra confirm the transition channels which are consistent with the PL emission.展开更多
A simple one-pot method was developed to prepare Pt Ni alloy nanoparticles,which can be self-decorated on multiwalled carbon nanotubes in [BMIm][BF4] ionic liquid.The nanohybrids are targeting stable nanocatalysts for...A simple one-pot method was developed to prepare Pt Ni alloy nanoparticles,which can be self-decorated on multiwalled carbon nanotubes in [BMIm][BF4] ionic liquid.The nanohybrids are targeting stable nanocatalysts for fuel cell applications.The sizes of the supported Pt Ni nanoparticles are uniform and as small as 1–2 nm.Pt-to-Ni ratio was controllable by simply selecting a Pt Ni alloy target.The alloy nanoparticles with Pt-to-Ni ratio of 1:1 show high catalytic activity and stability for methanol electro-oxidation.The performance is much higher compared with those of both Pt-only nanoparticles and commercial Pt/C catalyst.The electronic structure characterization on the Pt Ni nanoparticles demonstrates that the electrons are transferred from Ni to Pt,which can suppress the CO poisoning effect.展开更多
In this study we investigated the enrichment ability of oxidized multiwalled carbon nanotubes （MWCNTs） and established a new method for the determination of trace cadmium in environment with flame atomic absorption ...In this study we investigated the enrichment ability of oxidized multiwalled carbon nanotubes （MWCNTs） and established a new method for the determination of trace cadmium in environment with flame atomic absorption spectrometry. The MWCNTs were oxidized by potassium permanganate under appropriate conditions before use as preconcentration packing. Parameters influencing the recoveries of target analytes were optimized. Under optimal conditions, the target analyte exhibited a good linearity （R^2=0.9992） over the concentration range 0.5-50 ng/ml. The detection limit and precision of the proposed method were 0.15 ng/ml and 2.06%, respectively. The proposed method was applied to the determination of cadmium in real-world environmental samples and the recoveries were in the range of 91.3%-108.0%. All these experimental results indicated that this new procedure could be applied to the determination of trace cadmium in environmental waters.展开更多
A nonenzymatic electrochemical sensor for glucose and fructose was fabricated that contained a glassy carbon electrode modified with a copper oxide (CuO)/multiwalled carbon nanotube (MWCNT) nanocomposite. The electroc...A nonenzymatic electrochemical sensor for glucose and fructose was fabricated that contained a glassy carbon electrode modified with a copper oxide (CuO)/multiwalled carbon nanotube (MWCNT) nanocomposite. The electrochemical properties of the CuO/MWCNT‐modified glassy carbon electrode were investigated. Two distinguishable anodic peaks were observed around 0.30 and 0.44 V corresponding to the oxidation of glucose and fructose, respectively, at the surface of the modified electrode. The detection limits for glucose and fructose were both 0.04 mmol/L. The sensor was used to simultaneously determine the concentrations of glucose and fructose in hydrolyzed sucrose samples, and to measure glucose in blood serum samples, demonstrating its potential as a nonenzymatic carbohydrate sensor.展开更多
Lithium-sulfur battery has become one of the most promising candidates for next generation batteries, and it is still restricted due to the low sulfur conductivity, large volume expansion and severe polysulfide shuttl...Lithium-sulfur battery has become one of the most promising candidates for next generation batteries, and it is still restricted due to the low sulfur conductivity, large volume expansion and severe polysulfide shuttling. Herein, we present a novel hybrid electrode with a ternary nanomaterial based on sulfur-impregnated multiwalled carbon nanotubes filled with ordered tin-monoxide nanoparticles （MWCNT-SnO/S）. Using a dry plasma reduction method, a mechanically robust material is prepared as a cathode host material for lithium-sulfur batteries. The MWCNT-SnO/S electrode exhibits high conductivity, good ability to capture polysulfides, and small volume change during a repeated charge-discharge process. In situ transmission electron microscopy and ultraviolet-visible absorption results indicate that the MWCNT-SnO host efficiently suppresses volume expansion during lithiation and reduces polysulfide dissolution into the electrolyte. Furthermore, the ordered SnO nanoparticles in the MWCNTs facilitate fast ion/electron transfer during the redox reactions by acting as connective links between the walls of the MWCNTs. The MWCNT-SnO/S cathode with a high sulfur content of 70 wt.% exhibits an initial discharge capacity of 1,682.4 mAh·g^-1 at 167.5 m·g^-1 （0.1 C rate） and retains a capacity of 530.1 mAh·g^-1 at 0.5 C after 1,000 cycles with nearly 100% Coulombic efficiency. Furthermore, the electrode exhibits the high capacity even at a high current rate of 20 C.展开更多
An efficient method using multiwalled carbon nanotubes(MWCNTs)as dispersive solid-phase extraction sorbent was established for determining chlorantraniliprole residues in fresh tea leaves,which are known to be a troub...An efficient method using multiwalled carbon nanotubes(MWCNTs)as dispersive solid-phase extraction sorbent was established for determining chlorantraniliprole residues in fresh tea leaves,which are known to be a troublesome matrix containing abundant pigments,via gas chromatography with an electron capture detector.Acetonitrile was used as the extraction solvent,with sodium chloride enhancing the analyte partition in the organic phase.The optimal mixture of MWCNTs and primary secondary amine(PSA)was based on the distribution of the target analyte recovery and on the clean-up efficiency;while matrix-matched calibration was recommended to combat the matrix effect.Mean recoveries of 95.2%–108.8%were obtained with intraday and interday precisions of less than 7.9%and 10.3%,respectively.Good linearity was observed for concentrations of 0.02–1.0 mg/kg with a correlation coefficient of 0.9984.The limits of detection and quantification were 0.005 mg/kg and 0.02 mg/kg,respectively.The method was employed to investigate the dissipation dynamics of chlorantraniliprole in fresh tea leaves with real field samples.Consequently,the dissipation rates of chlorantraniliprole in fresh tea leaves followed pseudo-first-order kinetics with a half-life of 1.9 d,and the average chlorantraniliprole residue content was below 0.02 mg/kg with a harvest withholding period of 14 d.展开更多
An amperometric hydrogen peroxide biosensor using a nanobiocomposite based on neutral red modified carbon nanotubes and co-immobilized glucose oxidase and horseradish peroxidase is reported. Modification of the nanobi...An amperometric hydrogen peroxide biosensor using a nanobiocomposite based on neutral red modified carbon nanotubes and co-immobilized glucose oxidase and horseradish peroxidase is reported. Modification of the nanobiocomposite electrode with neutral red resulted in a sensitive, low-cost and reliable H_2O_2 sensor. The use of carbon nanotubes, as the conductive part of the composite, facilitated fast electron transfer rates. The biosensor was characterized for the influence of p H, potential and temperature. A remarkable feature of the biosensor is the detection of H_2O_2 at low applied potentials where the noise level and interferences are minimal. The sensor has a fast steady-state measuring time of 10 s with a quick response(2 s). The biosensor showed a linear range from 15 n M to 45 m M of H_2O_2 and a detection limit of 5 n M. Nafion, which is used as a binder, makes the determination free from other electroactive substances. The repeatability, reproducibility,stability and analytical performance of the sensor are very good.展开更多
Synthesised triphenylphosphine-linked multiwalled carbon nanotubes （Tpp-MWCNTs） were used to study the adsorption of nickel in aqueous solutions and their adsorption capabilities were compared with purified MWCNTs.T...Synthesised triphenylphosphine-linked multiwalled carbon nanotubes （Tpp-MWCNTs） were used to study the adsorption of nickel in aqueous solutions and their adsorption capabilities were compared with purified MWCNTs.The adsorption capacity increased with an increase in pH for all adsorbents.The adsorption equilibrium was reached in 40 and 30 min for purified MWCNTs and Tpp-MWCNTs,respectively.Both Freundlich and Langmuir isotherms used to investigate the adsorption process fitted the experimental data well with the correlation coefficient R 2 close to 1 for all adsorbents.On the other hand,the experimental data fitted well with a pseudo secondorder model.The speciation of nickel also influenced the adsorption on the purified and Tpp-MWCNTs.The adsorbents used in this study showed superior adsorption capacity when compared to other adsorbents reported in the literature.展开更多
Nanocomposite of Co3O4 and multiwalled carbon nanotube (MCNT) was synthesised using one step solvothermal method, and an electrochemical non-enzymatic glucose sensor (Co3O4-MCNT/GCE) was successfully constructed by a ...Nanocomposite of Co3O4 and multiwalled carbon nanotube (MCNT) was synthesised using one step solvothermal method, and an electrochemical non-enzymatic glucose sensor (Co3O4-MCNT/GCE) was successfully constructed by a dropping method. The obtained Co3O4 and Co3O4- MCNT were characterized and investigated by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). Quantitative analysis of glucose was performed using the amperometric (i–t) method, and plot of current difference versus concentration of glucose was linear in the range of 1.0–122μmol/L, with a linear correlation coefficient (R^2) of 0.9983 and limit of detection (LOD) of 0.28μmol/L. Sensitivity of this sensor was evaluated as 2550μA L mmol^-1 cm^-2. This new sensor produced satisfactory reproducibility and stability and was applied to monitor trace amounts of glucose in human serum samples.展开更多
In this work,an electrochemical chiral sensor of a nanowire-like chiral metal-organic framework/multiwalled carbon nanotube-chitosan/glassy carbon electrode(D-MOF/MWCNTs-CS/GCE)was proposed for the enantiorecognition ...In this work,an electrochemical chiral sensor of a nanowire-like chiral metal-organic framework/multiwalled carbon nanotube-chitosan/glassy carbon electrode(D-MOF/MWCNTs-CS/GCE)was proposed for the enantiorecognition of L/D-tryptophan(L/D-Trp).The asymmetrical spatial structure of D-MOF provides the feasibility for the enantiorecognition of Trp enantiomers.Moreover,differential pulse voltammetry(DPV)was carried out to be the detection method and the DPV peak potential difference(ΔEp)between L-Trp and D-Trp was referred as the index of the enantiorecognition performance.Several parameters,such as mass ratios and drop-coated volume of MWCNTs-CS,drop-coated volume and concentration of D-MOF,pH and detection temperature of D-MOF/MWCNTs-CS/GCE were optimized for the largestΔEp value.And the molecular dynamics(MD)simulation was used to elucidate the enantiorecognition mechanism.Furthermore,the proportions of D-Trp(D-Trp%)in Trp mixtures were detected in a good linear relationship with the DPV peak potentials(Ep),and the proposed electrochemical chiral sensor exhibited good reproducibility,stability and enantiorecognition ability.Additionally,the proposed electrochemical chiral sensor(D-MOF/MWCNTs-CS/GCE)has a good application prospect in the fields of biomedicine,clinical diagnosis,chemical production,pharmaceuticals safety and so on.展开更多
Cu2O and Cul were supported on multiwalled carbon nanotubes （MWCNTs） using a wet impregna- tion method, and the resulting materials were fully characterized by powder X-ray diffraction, Fourier transform infrared sp...Cu2O and Cul were supported on multiwalled carbon nanotubes （MWCNTs） using a wet impregna- tion method, and the resulting materials were fully characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy, transmission electron microscopy, and temperature-programmed desorption with ammonia analysis. The results of these experiments revealed that Cu2O and CuI were deposited on the MWCNTs in the cubic and γ phases, respectively. These results also showed that the Cu-containing MWCNTs exhibited weak to strong electron-accepting （Lewis acidic） properties. The catalytic activities of these materials were studied for the synthesis of biologically significant N-（pyridin-2-yl）benzamides via the oxidative amidation of aryl aldehydes with 2-aminopyridines. The yields of the products were in the range 50%-95% with 100% selectivity. Notably, the CuI/MWCNT catalyst was much more effective than the Cu2O/MWCNT catalyst with respect to the isolated yield of the product, although the latter of these two catalysts exhibited much better recyclability. A preferential interaction was observed between the polar nature of the acid-activated MWCNTs and the ionic Cu2O compared with covalent CuL The differences in these interactions had a significant impact on the rate of the nucleophilic attack of the amino group of 2-aminopyridine substrate on the carbonyl group of the aryl aldehyde.展开更多
The present work has focused on the modification of multiwalled carbon nanotube with a ligand,l-（2-pyridylazo）-2-naphthol, and its potential application for the development of a new,simple and selective modified gla...The present work has focused on the modification of multiwalled carbon nanotube with a ligand,l-（2-pyridylazo）-2-naphthol, and its potential application for the development of a new,simple and selective modified glassy carbon electrode for stripping voltammetric determination of Cd（Ⅱ）.The analytical curve for Cd（Ⅱ） ions covered the linear range varying from 0.8 up to 220.4μgL^（-1）.The limit of detection was found to be 0.1μgL^（-1）,while the relative standard deviation（RSD） at 50.0μgL^（-1） was 1.8%（n=5）.This modified electrode was successfully applied for determination of Cd（Ⅱ） in some water samples.展开更多
Maize tassel-multiwalled carbon nanotube (MT-MWCNT) composite has been used as a matrix for physical adsorption of horseradish peroxidase (HRP) onto the surface of a glassy carbon electrode through electrostatic inter...Maize tassel-multiwalled carbon nanotube (MT-MWCNT) composite has been used as a matrix for physical adsorption of horseradish peroxidase (HRP) onto the surface of a glassy carbon electrode through electrostatic interactions. The HRP/MT-MWCNT biosensor was applied for the detection of Zn2+ in aqueous solution. The biosensor designed was able to determine Zn2+ in the range of 0.35 - 12 mg/L with a detection limit of 7.5 μg/L. The inhibition was found to be reversible and uncompetitive when data were modeled using the Dixon and Cornish-Bowden plots. The biosensor was found to have good repeatability, reproducibility and high selectivity. The developed biosensor can be used to detect other HRP inhibiting trace metal ions.展开更多
文摘Graphene oxide （GO）-multiwalled carbon nanotube （MWCNT） composite was synthesized and characterized by X-ray diffraction, atomic force microscopy, scanning electron microscopy, micro Raman, Fourier transform infrared and ultraviolet-visible near infrared spectroscopy techniques. Spectral characteris- tics of cladding modified fiber optic gas sensors were studied for various concentrations of ammonia, ethanol and methanol at 27 ℃. Thickness of the gas sensing layer was controlled by varying the concentration of composite in ethanol medium （0.5 and 1 mg/mL） for three times dipping process. The O.S mg/ mL concentrated GO-MWCNT coated sensor showed 1.20, 1.40 and 1.15 times higher sensitivity than the GO coated sensor for ammonia, ethanol and methanol vapors, respectively. Furthermore, it exhibited 1.50, 1.80 and 1.80 times better sensitivity than 1 mg/mL concentrated GO-MWCNT coated sensor for ammonia, ethanol and methanol vapors, respectively. The presence of functional groups in GO increased the sen- sitivity. This is mainly attributed to the effective electron charge transfer between the composite materials and analytes.
基金This work was financially supported by the Natural Science Foundation of Guangdong Province, China (No. 04300695) and the Starting-up Research Foundation of Jinan University (No 51204022)
文摘Copper has been deposited on the surface of multiwailed carbon nanombes （MWNTs） and inside MWNTs by electroless deposition. The as-prepared Cu-MWNT composite materials have been characterized by X-ray diffractometer （XRD）, transmission electron microscopy （TEM）, and electrochemical measurement. XRD analyses showed that Cu was a face-centered cubic （fcc） structure. The average size of Cu was calculated by Scherrer＇s formula from XRD data, and it was 11 nm. TEM revealed that Cu grains on the surface of MWNTs were uniform with the sizes of about 30-60 nm. The electrochemical measurement indicated that Cu-MWNT composite materials possessed fine electron conductivity.
基金Acknowledgements The financial supports received from Guangdong Natural Science Funds for Distinguished Young Scholar （No. 2016A030306031）, the National Natural Science Foundation of China （No. 21576093）, the Guangdong Program for Support of Top-notch Young Professionals （No. 2015TQ01N327）, Pearl River and S＆T Nova Program of Guangzhou （No. 201610010039）, and Fundamental Research Funds for the Central Universities are gratefully acknowledged.
文摘Efficient separation and transfer of photogenerated electron/hole as well as enhanced visible light absorption play essential roles in photocatalytic reactions. To promote the photocatalytic reduction of Cr（VI）, a toxic heavy metal ion, multiwalled carbon nanotube （MWCNT） was introduced as an electron acceptor into NH2-MIL-68（In）. This led to the growth of a willow leaf-like metal-organic framework （MOF） on an MWCNT backbone forming MWCNT/NH2-MIL-68（In） （PL-1）, which showed a highly efficient transfer of photogenerated carriers. Moreover, MWCNT incorporation introduced more mesopores for Cr（VI） diffusion and enhanced the visible light adsorption without lowering the conduction band position. As a result, the photocatalytic kinetic constant of PL-1 was found to be almost three times higher than that of the parent NH2-MIL-68（In）. Thus, growing MOFs on MWCNTs provides a facile and promising solution for effective remediation of environmental pollution by utilizing solar energy. This work provides the first example of using MWCNT/MOF composites for photocatalytic reactions.
文摘The present study focuses on the thermal response of carbon fiber-reinforced phenolic composites, where the matrix has been modified with different reinforcements. Two types of materials, multiwalled carbon nanotubes and zirconium diboride （ZrB2）, were used in a new design of mixture to produce the heat- resistant ablative composite system. The CNT/ZrB2/carbon/phenolic nanocomposite （Z/NT-CR） system corresponding to CNT/carbon/phenolic nanocomposite （NT-CR） showed a reasonable decrease in mass loss and the ablation rate as compared to carbon/phenolic composite （CR）. However, substantial drop in two factors was found for Z/NT-CR as compared to carbon/phenolic and NT-CR. Ablation mechanisms for all three composites were investigated by thermal gravimetric analysis in conjunction with micro- structural studies using a field emission scanning electron microscope. The microstructural studies revealed that CNTs acted as an ablation resistant phase for protection against 2000 ℃, and the conversion from ZrB2 to ZrO2 played an important role as an insulator in the performance of char layer in the ablation resistance.
文摘The effects of three types of electrically-inert fillers, calcium carbonate （CaCO_3）, talc and glass fiber （GF）, on electrical resistivity, crystallization behavior and dynamic mechanical properties of poly（m-xylene adipamide） （MXD6）/multiwalled carbon nanotube （MWCNT） composites are investigated. The electrical resistivity of MXD6/MWCNT composites is significantly reduced with the addition of inert fillers due to the volume-exclusion effect that leads to increased effective concentration of MWCNTs in MXD6 matrix and also due to improved MWCNT dispersion. The crystallization temperature of MXD6 increases with the addition of MWCNTs, indicating that MWCNTs can act as nucleating agent and induce crystallization of MXD6. The incorporation of inert fillers has no further effect on crystallization behavior of MXD6, but significantly improves the storage modulus of MXD6/MWCNT composite, demonstrating that CaCO_3, talc and GF filled MXD6/MWCNT composites are very promising materials with not only improved electrical property but also excellent mechanical properties.
基金This work was supported by the Creative Talented Person＇s Fund of Henan Province （No. [20051126）；Natural Science Foundation of Henan Province （No. 072300460010）；the Fund of Henan Normal University （No. 2006PL06）；the grants from the Henan Key Laboratory for environmental pollution control.
文摘This paper described a new method for the trace determination of fenpropathrin, cyhalothrin and deltamethrin using multiwalled carbon nanotubes （MWCNTs） cartridge. Important parameters, such as the sample pH, eluent and its volume, sample flow rate and sample volume were investigated in detail. The linear ranges, the detection limits, and precisions （R.S.D.） were in the range of 0.1- 40 μg L^-11, 1.34.3 ng L^-1 and 2.3-2.8%, respectively. The performance of the proposed method was validated with real water samples, and the spiked recoveries were in the range of 91.7-117.8%, respectively. The experimental results demonstrated that the proposed method was an excellent alternative for the routine analysis of such pollutants in environmental samples. 2007 Qing Xiang Zhou. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
文摘In this paper the multiwalled carbon nanotubes （MWNTs） were synthesized by a chemical vapour deposition and the SEM graph shows that the sample has good construction. The micro-Raman spectrum shows the characteristic line of the MWNTs and an additional line produced by the defects on the outer surface of MWNTs. The photoluminescence （PL） spectra observed experimentally are variable under different excitation wavelengths and the strong excitation wavelength dependence of luminescence indicates a distribution of emitters which include electron π in excited states and the Van Hove singularities. The absorption spectra confirm the transition channels which are consistent with the PL emission.
基金supported by the National Natural Science Foundation of China(No.61274019)the Soochow University-Western University Joint Centre for Synchrotron Radiation Research+1 种基金the Collaborative Innovation Center of Suzhou Nano Science & Technologythe Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘A simple one-pot method was developed to prepare Pt Ni alloy nanoparticles,which can be self-decorated on multiwalled carbon nanotubes in [BMIm][BF4] ionic liquid.The nanohybrids are targeting stable nanocatalysts for fuel cell applications.The sizes of the supported Pt Ni nanoparticles are uniform and as small as 1–2 nm.Pt-to-Ni ratio was controllable by simply selecting a Pt Ni alloy target.The alloy nanoparticles with Pt-to-Ni ratio of 1:1 show high catalytic activity and stability for methanol electro-oxidation.The performance is much higher compared with those of both Pt-only nanoparticles and commercial Pt/C catalyst.The electronic structure characterization on the Pt Ni nanoparticles demonstrates that the electrons are transferred from Ni to Pt,which can suppress the CO poisoning effect.
基金Project supported by the Hi-Tech Research and Development Program (863) of China (No.2006AA06Z424)Personal Innovation Foundation of Universities in Henan Province (No.[2005]-126)+1 种基金Youth Science Foundation of Henan Normal University (No.2004005)Natural Science Foundation of Henan Province (No.072300460010).
文摘In this study we investigated the enrichment ability of oxidized multiwalled carbon nanotubes （MWCNTs） and established a new method for the determination of trace cadmium in environment with flame atomic absorption spectrometry. The MWCNTs were oxidized by potassium permanganate under appropriate conditions before use as preconcentration packing. Parameters influencing the recoveries of target analytes were optimized. Under optimal conditions, the target analyte exhibited a good linearity （R^2=0.9992） over the concentration range 0.5-50 ng/ml. The detection limit and precision of the proposed method were 0.15 ng/ml and 2.06%, respectively. The proposed method was applied to the determination of cadmium in real-world environmental samples and the recoveries were in the range of 91.3%-108.0%. All these experimental results indicated that this new procedure could be applied to the determination of trace cadmium in environmental waters.
基金The Iranian Nanotechnology Initiative,Research Council of Isfahan University of Technology,and Centre of Excellence in Sensor and Green Chemistry
文摘A nonenzymatic electrochemical sensor for glucose and fructose was fabricated that contained a glassy carbon electrode modified with a copper oxide (CuO)/multiwalled carbon nanotube (MWCNT) nanocomposite. The electrochemical properties of the CuO/MWCNT‐modified glassy carbon electrode were investigated. Two distinguishable anodic peaks were observed around 0.30 and 0.44 V corresponding to the oxidation of glucose and fructose, respectively, at the surface of the modified electrode. The detection limits for glucose and fructose were both 0.04 mmol/L. The sensor was used to simultaneously determine the concentrations of glucose and fructose in hydrolyzed sucrose samples, and to measure glucose in blood serum samples, demonstrating its potential as a nonenzymatic carbohydrate sensor.
文摘Lithium-sulfur battery has become one of the most promising candidates for next generation batteries, and it is still restricted due to the low sulfur conductivity, large volume expansion and severe polysulfide shuttling. Herein, we present a novel hybrid electrode with a ternary nanomaterial based on sulfur-impregnated multiwalled carbon nanotubes filled with ordered tin-monoxide nanoparticles （MWCNT-SnO/S）. Using a dry plasma reduction method, a mechanically robust material is prepared as a cathode host material for lithium-sulfur batteries. The MWCNT-SnO/S electrode exhibits high conductivity, good ability to capture polysulfides, and small volume change during a repeated charge-discharge process. In situ transmission electron microscopy and ultraviolet-visible absorption results indicate that the MWCNT-SnO host efficiently suppresses volume expansion during lithiation and reduces polysulfide dissolution into the electrolyte. Furthermore, the ordered SnO nanoparticles in the MWCNTs facilitate fast ion/electron transfer during the redox reactions by acting as connective links between the walls of the MWCNTs. The MWCNT-SnO/S cathode with a high sulfur content of 70 wt.% exhibits an initial discharge capacity of 1,682.4 mAh·g^-1 at 167.5 m·g^-1 （0.1 C rate） and retains a capacity of 530.1 mAh·g^-1 at 0.5 C after 1,000 cycles with nearly 100% Coulombic efficiency. Furthermore, the electrode exhibits the high capacity even at a high current rate of 20 C.
基金Science and Technology Project of Suzhou(Grant Nos.:SNG201622 and SNG201644)。
文摘An efficient method using multiwalled carbon nanotubes(MWCNTs)as dispersive solid-phase extraction sorbent was established for determining chlorantraniliprole residues in fresh tea leaves,which are known to be a troublesome matrix containing abundant pigments,via gas chromatography with an electron capture detector.Acetonitrile was used as the extraction solvent,with sodium chloride enhancing the analyte partition in the organic phase.The optimal mixture of MWCNTs and primary secondary amine(PSA)was based on the distribution of the target analyte recovery and on the clean-up efficiency;while matrix-matched calibration was recommended to combat the matrix effect.Mean recoveries of 95.2%–108.8%were obtained with intraday and interday precisions of less than 7.9%and 10.3%,respectively.Good linearity was observed for concentrations of 0.02–1.0 mg/kg with a correlation coefficient of 0.9984.The limits of detection and quantification were 0.005 mg/kg and 0.02 mg/kg,respectively.The method was employed to investigate the dissipation dynamics of chlorantraniliprole in fresh tea leaves with real field samples.Consequently,the dissipation rates of chlorantraniliprole in fresh tea leaves followed pseudo-first-order kinetics with a half-life of 1.9 d,and the average chlorantraniliprole residue content was below 0.02 mg/kg with a harvest withholding period of 14 d.
基金Department of Science and Technology(DST)Government of India,for sanctioning financial assistance for executing this programme under Nanomaterials Science and Technology Initiative Programmethe Council of Scientific and Industrial Research(CSIR),Government of India,for granting her fellowship for executing this programme
文摘An amperometric hydrogen peroxide biosensor using a nanobiocomposite based on neutral red modified carbon nanotubes and co-immobilized glucose oxidase and horseradish peroxidase is reported. Modification of the nanobiocomposite electrode with neutral red resulted in a sensitive, low-cost and reliable H_2O_2 sensor. The use of carbon nanotubes, as the conductive part of the composite, facilitated fast electron transfer rates. The biosensor was characterized for the influence of p H, potential and temperature. A remarkable feature of the biosensor is the detection of H_2O_2 at low applied potentials where the noise level and interferences are minimal. The sensor has a fast steady-state measuring time of 10 s with a quick response(2 s). The biosensor showed a linear range from 15 n M to 45 m M of H_2O_2 and a detection limit of 5 n M. Nafion, which is used as a binder, makes the determination free from other electroactive substances. The repeatability, reproducibility,stability and analytical performance of the sensor are very good.
基金The Grant-Holder-Linked Bursary received from the National Research Foundation and the bursary granted by the Department of Chemical Technology to Mr. A. A
文摘Synthesised triphenylphosphine-linked multiwalled carbon nanotubes （Tpp-MWCNTs） were used to study the adsorption of nickel in aqueous solutions and their adsorption capabilities were compared with purified MWCNTs.The adsorption capacity increased with an increase in pH for all adsorbents.The adsorption equilibrium was reached in 40 and 30 min for purified MWCNTs and Tpp-MWCNTs,respectively.Both Freundlich and Langmuir isotherms used to investigate the adsorption process fitted the experimental data well with the correlation coefficient R 2 close to 1 for all adsorbents.On the other hand,the experimental data fitted well with a pseudo secondorder model.The speciation of nickel also influenced the adsorption on the purified and Tpp-MWCNTs.The adsorbents used in this study showed superior adsorption capacity when compared to other adsorbents reported in the literature.
基金the financial support of this study by the National Natural Science Foundation of China(NSFC, No. 31860468)
文摘Nanocomposite of Co3O4 and multiwalled carbon nanotube (MCNT) was synthesised using one step solvothermal method, and an electrochemical non-enzymatic glucose sensor (Co3O4-MCNT/GCE) was successfully constructed by a dropping method. The obtained Co3O4 and Co3O4- MCNT were characterized and investigated by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS). Quantitative analysis of glucose was performed using the amperometric (i–t) method, and plot of current difference versus concentration of glucose was linear in the range of 1.0–122μmol/L, with a linear correlation coefficient (R^2) of 0.9983 and limit of detection (LOD) of 0.28μmol/L. Sensitivity of this sensor was evaluated as 2550μA L mmol^-1 cm^-2. This new sensor produced satisfactory reproducibility and stability and was applied to monitor trace amounts of glucose in human serum samples.
基金supported by the National Key R&D Program of China(No.2019YFA0904104).
文摘In this work,an electrochemical chiral sensor of a nanowire-like chiral metal-organic framework/multiwalled carbon nanotube-chitosan/glassy carbon electrode(D-MOF/MWCNTs-CS/GCE)was proposed for the enantiorecognition of L/D-tryptophan(L/D-Trp).The asymmetrical spatial structure of D-MOF provides the feasibility for the enantiorecognition of Trp enantiomers.Moreover,differential pulse voltammetry(DPV)was carried out to be the detection method and the DPV peak potential difference(ΔEp)between L-Trp and D-Trp was referred as the index of the enantiorecognition performance.Several parameters,such as mass ratios and drop-coated volume of MWCNTs-CS,drop-coated volume and concentration of D-MOF,pH and detection temperature of D-MOF/MWCNTs-CS/GCE were optimized for the largestΔEp value.And the molecular dynamics(MD)simulation was used to elucidate the enantiorecognition mechanism.Furthermore,the proportions of D-Trp(D-Trp%)in Trp mixtures were detected in a good linear relationship with the DPV peak potentials(Ep),and the proposed electrochemical chiral sensor exhibited good reproducibility,stability and enantiorecognition ability.Additionally,the proposed electrochemical chiral sensor(D-MOF/MWCNTs-CS/GCE)has a good application prospect in the fields of biomedicine,clinical diagnosis,chemical production,pharmaceuticals safety and so on.
基金DST-SERB for the financial support for this research work(Project number:SERB/F/3690/2013-14)
文摘Cu2O and Cul were supported on multiwalled carbon nanotubes （MWCNTs） using a wet impregna- tion method, and the resulting materials were fully characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy, transmission electron microscopy, and temperature-programmed desorption with ammonia analysis. The results of these experiments revealed that Cu2O and CuI were deposited on the MWCNTs in the cubic and γ phases, respectively. These results also showed that the Cu-containing MWCNTs exhibited weak to strong electron-accepting （Lewis acidic） properties. The catalytic activities of these materials were studied for the synthesis of biologically significant N-（pyridin-2-yl）benzamides via the oxidative amidation of aryl aldehydes with 2-aminopyridines. The yields of the products were in the range 50%-95% with 100% selectivity. Notably, the CuI/MWCNT catalyst was much more effective than the Cu2O/MWCNT catalyst with respect to the isolated yield of the product, although the latter of these two catalysts exhibited much better recyclability. A preferential interaction was observed between the polar nature of the acid-activated MWCNTs and the ionic Cu2O compared with covalent CuL The differences in these interactions had a significant impact on the rate of the nucleophilic attack of the amino group of 2-aminopyridine substrate on the carbonyl group of the aryl aldehyde.
文摘The present work has focused on the modification of multiwalled carbon nanotube with a ligand,l-（2-pyridylazo）-2-naphthol, and its potential application for the development of a new,simple and selective modified glassy carbon electrode for stripping voltammetric determination of Cd（Ⅱ）.The analytical curve for Cd（Ⅱ） ions covered the linear range varying from 0.8 up to 220.4μgL^（-1）.The limit of detection was found to be 0.1μgL^（-1）,while the relative standard deviation（RSD） at 50.0μgL^（-1） was 1.8%（n=5）.This modified electrode was successfully applied for determination of Cd（Ⅱ） in some water samples.
文摘Maize tassel-multiwalled carbon nanotube (MT-MWCNT) composite has been used as a matrix for physical adsorption of horseradish peroxidase (HRP) onto the surface of a glassy carbon electrode through electrostatic interactions. The HRP/MT-MWCNT biosensor was applied for the detection of Zn2+ in aqueous solution. The biosensor designed was able to determine Zn2+ in the range of 0.35 - 12 mg/L with a detection limit of 7.5 μg/L. The inhibition was found to be reversible and uncompetitive when data were modeled using the Dixon and Cornish-Bowden plots. The biosensor was found to have good repeatability, reproducibility and high selectivity. The developed biosensor can be used to detect other HRP inhibiting trace metal ions.
