Pd nanoparticles(Pd-NPs)were prepared and directly anchored on the surface of multi-walled carbon nanotubes(MWCNTs)in the absence of chemical reduction agent,where MWCNTs were used as both the chemical reduction agent...Pd nanoparticles(Pd-NPs)were prepared and directly anchored on the surface of multi-walled carbon nanotubes(MWCNTs)in the absence of chemical reduction agent,where MWCNTs were used as both the chemical reduction agent and the support substrate of Pd-NPs.Effect of various surfactants on the in situ deposition of PdNPs on MWCNTs was investigated.When MWCNTs were modified with a cationic surfactant(hexadecyl trimethyl ammonium bromide,CTAB),the amount of the Pd-NPs(Pd-NP/CTAB-MWCNT)generated by such an in situ deposition method gets a notable increase,and the size of the as-synthesized Pd-NPs becomes smaller,compared with those in the absence of any surfactant(Pd-NP/MWCNT)or in the presence of an anionic surfactant SDS(Pd-NP/SDS-MWCNT)and a neutral surfactant OP(PdNP/OP-MWCNT).Results show that the MWCNTs modified with CTAB are propitious to the in situ reduction of Pd2?.Among the prepared catalysts,Pd-NP/CTABMWCNT displays the highest electroactivity for ethanol oxidation in alkaline media.展开更多
Platinum-based nanocomposites have been considered as one of the most promising catalysts for methanol oxidation reactions(MORs), which yet still suffer from low electrochemical activity and electron-transfer properti...Platinum-based nanocomposites have been considered as one of the most promising catalysts for methanol oxidation reactions(MORs), which yet still suffer from low electrochemical activity and electron-transfer properties. Apart from van-der-Waals heterostructures,herein, we report a novel nanocomposite with the structure of Pt–Ru bimetallic nanoparticles covalently-bonded onto multi-walled carbon nanotubes (MWCNTs)(Pt–Ru@MWCNT), which have been successfully fabricated via a facile and green synthesis method. It is demonstrated that the Pt–Ru@MWCNT nanocomposite possesses much enhanced electrocatalytic activity with the electrochemical active surface area(ECSA) of 110.4 m^(2)·g^(-1)for Pt towards MOR, which is 2.67 and 4.0 times higher than those of 20wt%commercial Pt@C and Pt-based nanocomposite prepared by other method, due to the improved electron-transfer properties originated from M–O–C covalent bonds. This work provides us a new strategy for the structural design of highly-efficient electrocatalysts in boosting MOR performance.展开更多
A sensitive electroanalytical method for quantification of pheniramine in pharmaceutical formulation has been investigated on the basis of the enhanced electrochemical response at glassy carbon electrode modified with...A sensitive electroanalytical method for quantification of pheniramine in pharmaceutical formulation has been investigated on the basis of the enhanced electrochemical response at glassy carbon electrode modified with multi-walled carbon nanotubes in the presence of sodium lauryl sulfate.The experimental results suggest that the phcniramine in anionic surfactant solution exhibits electrocatalytic effect resulting in a marked enhancement of the peak current response.Peak current response is linearly dependent on the concentration of pheniramine in the range 200-1500 μg/mL with correlation coefficient 0.9987.The limit of detection is 58.31 μg/m L.The modified electrode shows good sensitivity and repeatability.展开更多
This work proposes the synthesis of the 5%wt Ru on MWCNT catalyst and the influence of feed rate and testing variables for low-temperature oxidation affecting the CO<sub>2</sub> yield. Morphology and incor...This work proposes the synthesis of the 5%wt Ru on MWCNT catalyst and the influence of feed rate and testing variables for low-temperature oxidation affecting the CO<sub>2</sub> yield. Morphology and incorporation of the nanoparticles in carbon nanotubes were investigated by specific surface area (BET method);thermogravimetric analyses (TGA);X-ray diffraction;Raman spectroscopy, transmission electron microscopy (TEM) and XPS. The conversions of CO and O<sub>2</sub> were mostly 100% in groups C1 and C2 (temperature between 200 and 500<span style="white-space:nowrap;">°</span>C with low WHSV). In order to assess the effect of mass on catalytic activity, condition C3 was tested at even lower temperatures. In the tested catalyst, high activity (100% CO and O<sub>2</sub> conversion) was observed, keeping it active under reaction conditions, suggesting oxi-reduction of the RuO<sub>2</sub> at surface without affecting the MWCNT but Lewis acid influencing the CO<sub>2</sub> yield.展开更多
Improving the performance of anode is a crucial step for increasing output power of marine sediment microbial fuel cells(MSMFCs)to drive marine monitor to work for a long term on the ocean floor.A pyrolyzed iron phtha...Improving the performance of anode is a crucial step for increasing output power of marine sediment microbial fuel cells(MSMFCs)to drive marine monitor to work for a long term on the ocean floor.A pyrolyzed iron phthalocyanine modified multi-walled carbon nanotubes composite(FePc/MWCNTs)has been utilized as a novel nodified anode in the MSMFC.Its structure of the composite modified anode and electrochemical performance have been investigated respectively in the paper.There is a substantial improvement in electron-transfer efficiency from the bacteria biofilm to the modified anode via the pyrolyzed FePc/MWCNTs composite based on their cyclic voltammetry(CV)and Tafel curves.The electron transfer kinetic activity of the FePc/MWCNTs-modified anode is 1.86 times higher than of the unmodified anode.The maximum power density of the modified MSMFC was 572.3±14 m W m^-2,which is 2.6 times larger than the unmodified one(218.3±11 m W m^-2).The anodic structure and cell scale would be greatly minimized to obtain the same output power by the modified MSMFC,so that it will make the MSMFC to be easily deployed on the remote ocean floor.Therefore,it would have a great significance for us to design a novel and renewable long term power source.Finally,a novel molecular synergetic mechanism is proposed to elucidate its excellent electrochemical performance.展开更多
Objective This study was aimed to investigate the toxic effects of 3 nanomaterials, i.e. multi-walled carbon nanotubes （MWCNTs）, graphene oxide （GO）, and reduced graphene oxide （RGO）, on zebrafish embryos. Metho...Objective This study was aimed to investigate the toxic effects of 3 nanomaterials, i.e. multi-walled carbon nanotubes （MWCNTs）, graphene oxide （GO）, and reduced graphene oxide （RGO）, on zebrafish embryos. Methods The 2-h post-fertilization （hpf） zebrafish embryos were exposed to MWCNTs, GO, and RGO at different concentrations （1, 5, 10, 50, 100 mg/L） for 96 h. Afterwards, the effects of the 3 nanomateria on spontaneous movement, heart rate, hatching rate, length of larvae, mortality, and malformations Is were evaluated. Results Statistical analysis indicated that RGO significantly inhibited the hatching of zebrafish embryos. Furthermore, RGO and MWCNTs decreased the length of the hatched larvae at 96 hpf. No obvious morphological malformation or mortality was observed in the zebrafish embryos after exposure to the three nanomaterials. Conclusion MWCNTs, GO, and RGO were all toxic to zebrafish embryos to influence embryos hatching and larvae length. Although no obvious morphological malformation and mortality were observed in exposed zebrafish embryos, further studies on the toxicity of the three nanomaterials are still needed.展开更多
The electrocatalytic oxidation of nitric oxide（NO） at a glass carbon electrode（GC） modified with functionalized single-walled carbon nanotubes（SWCNTs） was investigated by cyclic voltammetry（CV） and electrochem...The electrocatalytic oxidation of nitric oxide（NO） at a glass carbon electrode（GC） modified with functionalized single-walled carbon nanotubes（SWCNTs） was investigated by cyclic voltammetry（CV） and electrochemical impedance spectroscopy（EIS）.It was found that the SWCNT modified electrode could speed greatly up the electron transfer rate compared with the bare GC electrode.After the SWCNT was treated with alkali or mixed acids,the reaction rate and activation energy of NO electrooxidation were changed to different extent.Chemical modification of the SWCNT surface is one of the most powerful methods to change the sensitivity of NO electrooxidation reaction.The modified electrode with SWCNT obtained by the firstly alkali treatment and then the mixed acids treatment was the best one for NO electrooxidation,the result of CV was also confirmed by that of EIS.The anodic processes of NO were recognized more clearly by exploring the reaction mechanism of NO electrooxidation at the SWCNT modified electrode.展开更多
A new chemically modified electrode(CME) immobilized on the surface of multi-wall carbon nanotubes functionalized with carboxylic groups was fabricated. The results indicate that the CME exhibits efficiently electroca...A new chemically modified electrode(CME) immobilized on the surface of multi-wall carbon nanotubes functionalized with carboxylic groups was fabricated. The results indicate that the CME exhibits efficiently electrocatalytic oxidation of 6-mercaptopurine(6-MP). The CME can be used as the working electrode in the liquid chromatography for the determination of 6-MP. The peak current of 6-MP is linearly changed with its concentration ranging from 4.0×10 -7 to 1.0×10 -4 mol/L with the calculated detection limit (S/N=3) of 2.0×10 -7 mol/L. Coupled with microdialysis sampling, the method has been successfully applied to assessing the content of 6-MP in rat blood.展开更多
In this work, noncovalent functionalization of multiwalled carbon nanotube （MWNT） with acridine orange （AO） by electropolymerization is studied. The obtained composite film is a viable alternate electrode material...In this work, noncovalent functionalization of multiwalled carbon nanotube （MWNT） with acridine orange （AO） by electropolymerization is studied. The obtained composite film is a viable alternate electrode material, non-toxic, chemical inert, not volatile, using to construct modified electrode. The new type modified electrode has both of unique properties of MWNT and poly acridine orange （POAO）, can provide good sensitivity, low limits of detection, good response precision, and superb response stability.展开更多
Acid-based purification process of multi-walled carbon nanotubes （MWNTs） produced via catalytic decomposition of methane with NiO/TiO2 as a catalyst is described. By combining the oxidation in air and the acid reflu...Acid-based purification process of multi-walled carbon nanotubes （MWNTs） produced via catalytic decomposition of methane with NiO/TiO2 as a catalyst is described. By combining the oxidation in air and the acid refluxes, the impurities, such as amorphous carbon, carbon nanoparticles, and the NiO/TiO2 catalyst, are eliminated. Scanning electron microscopy （SEM） and transmission electron microscopy （TEM） images confirm the removal of the impurities. The percentage of the carbon nanotubes purity was analyzed using thermal gravimetric analysis （TGA）. Using this process, 99.9 wt% purity of MWNTs was obtained.展开更多
Hydrogen peroxide(H2O2)is a very useful chemical reagent,but the current industrial methods for its production suffer from serious energy consumption problems.Using high-activity and high-selectivity catalysts to elec...Hydrogen peroxide(H2O2)is a very useful chemical reagent,but the current industrial methods for its production suffer from serious energy consumption problems.Using high-activity and high-selectivity catalysts to electrocatalyze the oxygen reduction reaction(ORR)through a two-electron(2e^-)pathway is a very promising route to produce H2O2.In this work,we obtained partially oxidized multi-walled carbon nanotubes(MWCNTs)with controlled structure and composition by oxidation with concentrated sulfate and potassium permanganate at 40℃ for 1 h(O-CNTs-40-1).The outer layers of O-CNTs-40-1 are damaged with defects and oxygen-containing functional groups,while the inner layers are maintained intact.The optimized structure and composition of the partially oxidized MWCNTs ensure that O-CNTs-40-1 possesses both a sufficient number of catalytic sites and good conductivity.The results of rotating ring disk electrode measurements reveal that,among all oxidized MWCNTs,O-CNTs-40-1 shows the greatest improvement in hydrogen peroxide selectivity(from ~ 30% to ~ 50%)and electron transfer number(from ~ 3.4 to ~ 3.0)compared to those of the raw MWCNTs.The results of electrochemical impedance spectroscopy measurements indicate that both the charge-transfer and intrinsic resistances of O-CNTs-40-1 are lower than those of the raw MWCNTs and of the other oxidized MWCNTs.Finally,direct tests of the H2O2 production confirm the greatly improved catalytic activity of O-CNTs-40-1 relative to that of the raw MWCNTs.展开更多
Objective To investigate in vitro cytotoxicity and oxidative stress response induced by multiwalled carbon nanotubes （MWCNTs）. Methods Cultured macrophages （murine RAW264.7 cells） and alveolar epithelium cells typ...Objective To investigate in vitro cytotoxicity and oxidative stress response induced by multiwalled carbon nanotubes （MWCNTs）. Methods Cultured macrophages （murine RAW264.7 cells） and alveolar epithelium cells type II （human A549 lung cells） were exposed to the blank control, DNA salt control, and the MWCNTs suspensions at 2.5, 10, 25, and 100 ug/mL for 24 h. Each treatment was evaluated by cell viability, cytotoxicity and oxidative stress. Results Overall, both cell lines had similar patterns in response to the cytotoxicity and oxidative stress of MWCNTs. DNA salt treatment showed no change compared to the blank control. In both cell lines, significant changes at the doses of 25 and 100 ug/mL treatments were found in cell viabilities, cytotoxicity, and oxidative stress indexes. The reactive oxygen species （ROS） generation was also found to be significantly higher at the dose of 10 ug/mL treatment, whereas no change was seen in most of the indexes. The ROS generation in both cell lines went up in minutes, reached the climax within an hour and faded down after several hours. Conclusion Exposure to MWCNTs resulted in a dose-dependent cytotoxicity in cultured RAW264.7 cells and A549 cells, that was closely correlated to the increased oxidative stress.展开更多
The microstructural evolution and oxidation resistance of multi-walled carbon nanotubes （MWCNTs） by di- rectly heating silicon powder and MWCNTs in a coke bed from 1000 to 1500 ~C are investigated with the aid of X-...The microstructural evolution and oxidation resistance of multi-walled carbon nanotubes （MWCNTs） by di- rectly heating silicon powder and MWCNTs in a coke bed from 1000 to 1500 ~C are investigated with the aid of X-ray diffraction （XRD）, scanning electron microscopy （SEM）, high resolution transmission electron microscopy （HRTEM） and thermogravimetry-differential scanning calorimetry （TG-DSC）. The results showed that the morphology and microstructure of MWCNTs did not change much after being treated from 1000 ~C to 1200 ~C. An obvious SiC coating was formed on the surface of MWCNTs from 1300 to 1400 ~C. Up to 1500 ~C, nearly all the MWCNTs transformed into SiC nanowires. The oxidation resistance of the treated MWCNTs was improved compared with as-received ones. Non-isothermal kinetics showed that the oxidation activation energy of the treated MWCNTs reached 208 kJ/mol, much higher than 264 k J/tool of as-received ones.展开更多
We have designed and prepared β-cyclodextrin （β-CD）-functionalized multi-walled nanotubes （MWCNTs-g-CD） for the oxidation of cinnamon oil to natural benzaldehyde under aqueous condi- tions. The synergistic effec...We have designed and prepared β-cyclodextrin （β-CD）-functionalized multi-walled nanotubes （MWCNTs-g-CD） for the oxidation of cinnamon oil to natural benzaldehyde under aqueous condi- tions. The synergistic effect of combining MWCNTs with β-CD led to a remarkable increase in the performance of the MWCNTs-g-CD for the catalytic oxidation of cinnamaldehyde, which exhibited 95% cinnamaldehyde conversion and 85% selectivity to natural benzaldehyde with a short reaction time of 10 rain. The MWCNTs-g-CD also exhibited outstanding recyclability with good stability, showing no discernible decrease in their catalytic activity over five reaction cycles.展开更多
Graphene possesses unique physical and chemical properties, which have inspired a wide range of potential biomedical applications. However, little is known about the adverse effects of graphene on the human body and e...Graphene possesses unique physical and chemical properties, which have inspired a wide range of potential biomedical applications. However, little is known about the adverse effects of graphene on the human body and ecological environment. The purpose of our work is to make assessment on the toxicity of graphene oxide (GO) against human cell line (human bone marrow neuroblastoma cell line and human epithelial carcinoma cell line) and zebrafish (Danio rerio) by comparing the toxic effects of GO with its sister, multi-walled carbon nanotubes (MWNTs). The results show that GO has a moderate toxicity to organisms since it can induce minor (about 20%) cell growth inhibition and slight hatching delay of zebrafish embryos at a dosage of 50 mg/L, but did not result in significant increase of apoptosis in embryo, while MWNTs exhibit acute toxicity leading to a strong inhibition of cell proliferation and serious morphological defects in developing embryos even at relatively low concentration of 25 mg/L. The distinctive toxicity of GO and MWNTs should be ascribed to the different models of interaction between nanomaterials and organisms, which arises from the different geometric structures of nanomaterials. Collectively, our work suggests that GO does actual toxicity to organisms posing potential environmental risks and the result is also shedding light on the geometrical structure-dependent toxicity of graphitic nanomaterials.展开更多
NADPH can be directly oxidized on a carbon nanotube modified glassy carbon (CNT/GC) electrode in phosphate buffer solution (pH=6.0) with a diminution of the overpotential of more than 700 mV. The anodic peak currents ...NADPH can be directly oxidized on a carbon nanotube modified glassy carbon (CNT/GC) electrode in phosphate buffer solution (pH=6.0) with a diminution of the overpotential of more than 700 mV. The anodic peak currents increase linearly with the increase of concentration of NADPH in the range of 5 x 10(-7) to 1 x 10(-3) mol/L with a detection limit of about 1 x 10-7 mol/L. The CNT/GC electrode exhibits high sensitivity, low potential and stability in detecting NADPH and thus might be used in biosensors to study the electrocatalytic reaction of important dehydrogenase-based biological systems.展开更多
Multi-walled carbon nanotubes （MWCNTs） were fabricated and oxidized by different concentrations of sodium hypochlorite （NaOC1） solutions. The untreated MWCNTs and modified MWCNTs were employed as adsorbents to stu...Multi-walled carbon nanotubes （MWCNTs） were fabricated and oxidized by different concentrations of sodium hypochlorite （NaOC1） solutions. The untreated MWCNTs and modified MWCNTs were employed as adsorbents to study their characterizations and adsorption performance of toluene, ethylbenzene and xylene isomers （TEX） in an aqueous solution. The physicochemical properties of MWCNTs were greatly affected after oxidation, which influences TEX adsorption capacity. The 3% NaOCl-oxidized MWCNTs shows the greatest enhancement in TEX adsorption, followed by the 30% NaOCl. More interestingly, the 15% NaOCl-oxidized MWCNTs has lower adsorption capacities than untreated MWCNTs. The adsorption mechanism of TEX on treated MWCNTs is attributed to the combined action of hydrophobic interaction, π-π bonding interaction between the aromatic ring of TEX and the oxygen-containing functional groups of MWCNTs and electrostatic interac- tion. 3% NaOCl solution could not only introduce much oxygen-containing functional groups on MWCNTs, but also lead to less damage for the pore structure. This suggests that the CNTs-3% NaOCl is efficient adsorbent for TEX and that they may possess good potential for TEX removal in wastewater treatment.展开更多
Nanoparticles(NPs)are widely used for their special physical properties and released into the natural environment.When two types of NPs exist in the same environment,the presence of one type of NP may affect the prope...Nanoparticles(NPs)are widely used for their special physical properties and released into the natural environment.When two types of NPs exist in the same environment,the presence of one type of NP may affect the properties of the other type of NP.This study investigated the toxic effects of multi-walled carbon nanotubes(MWCNTs)and copper oxide nanoparticles(Cu O NPs)on Tetradesmus obliquus.Both NPs had toxic effects on algae,and the toxic effects of MWCNTs were significantly stronger than Cu O NPs which the 96-hr median effective concentration to algae were 33.8 and 169.2 mg/L,respectively.Oxidative stress and cell membrane damage were the main reasons for the toxicity of NPs to algae,and they were concentration-dependent,and the existence of Cu O NPs in some groups reduced cell membrane damage caused by MWCNTs which may because that Cu O NPs formed heteroaggregation with MWCNTs,reducing the contact of nanoparticles with cell membranes,then reducing physical damage.Scanning electron microscopy(SEM)and transmission electron microscope(TEM)results indicated cell damage,the heteroaggregation of MWCNTs-Cu O NPs and obvious nanoparticles internalization.In some groups,the presence of Cu O NPs significantly reduced reactive oxygen species(ROS)level induced by MWCNTs.However,for the highest concentration group,the ROS level was much higher than that of the two NPs alone treatment groups,which might be related to the high concentration of MWCNTs promoting the internalization of Cu O NPs.MWCNTs and Cu O NPs affected and interacted with each other,causing more complex toxic effects on aquatic organisms.展开更多
This work describes the electrochemical behaviour of ibuprofen on two types of multi-walled carbon nanotubes based composite electrodes, i.e., multi-walled carbon nanotubes-epoxy （MWCNT） and silver-modified zeolite-...This work describes the electrochemical behaviour of ibuprofen on two types of multi-walled carbon nanotubes based composite electrodes, i.e., multi-walled carbon nanotubes-epoxy （MWCNT） and silver-modified zeolite-multi-wailed carbon nanotubes-epoxy （AgZMWCNT） composites electrodes. The composite electrodes were obtained using two-roll mill procedure. SEM images of surfaces of the composites revealed a homogeneous distribution of the composite components within the epoxy matrix. AgZMWCNT composite electrode exhibited the better electrical conductivity and larger electroactive surface area. The electrochemical determination of ibuprofen （IBP） was achieved using AgZMWCNT by cyclic voltammetry, differential-pulsed voltammetry, square-wave voltammetry and chronoamperometry. The IBP degradation occurred on both composite electrodes under controlled electrolysis at 1.2 and 1.75 V vs. Ag/AgCl, and IBP concentration was determined comparatively by differential-pulsed voltammetry, under optimized conditions using AgZMWCNT electrode and UV-Vis spectrophotometry methods to determine the IBP degradation performance for each electrode. AgZMWCNT electrode exhibited a dual character allowing a double application in IBP degradation process and its control.展开更多
The functionalization of multi-walled carbon nanotubes （MWCNTs） by ozone treatment has been sys- tematically investigated by using Raman spectroscopy, transmission electron microscopy （TEM）, Fourier transform inha...The functionalization of multi-walled carbon nanotubes （MWCNTs） by ozone treatment has been sys- tematically investigated by using Raman spectroscopy, transmission electron microscopy （TEM）, Fourier transform inhared spectroscopy （FTIR）, X-ray photoelectron spectroscopy （XPS）, organic elemental anal- ysis （OEA） and Boehm titration. The results showed that the functionalization process occurred at defective sites （opened mouths, tube caps, debris, etc.） before opening caps and truncating walls, and finally the graphitic structure was deteriorated. The surface oxygen content first increased with the treatment time but kept at around 8.0 wt% after 5 h. The analysis of the distribution of oxygen-containing groups re- vealed that phenolic hydroxyl was gradually converted to carboxyl and lactone, The carboxyl was found to play a pivotal role to reduce the over-potentials when we used the functionalized MWCNTs as the cat- alyst for oxygen reduction reaction （ORR）.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 21376070 and 20876038)Scientific Research Fund of Hunan Provincial Edu- cation Department (No. 11K023)Hunan Provincial Natural Science Foundation of China (14JJ2096)
文摘Pd nanoparticles(Pd-NPs)were prepared and directly anchored on the surface of multi-walled carbon nanotubes(MWCNTs)in the absence of chemical reduction agent,where MWCNTs were used as both the chemical reduction agent and the support substrate of Pd-NPs.Effect of various surfactants on the in situ deposition of PdNPs on MWCNTs was investigated.When MWCNTs were modified with a cationic surfactant(hexadecyl trimethyl ammonium bromide,CTAB),the amount of the Pd-NPs(Pd-NP/CTAB-MWCNT)generated by such an in situ deposition method gets a notable increase,and the size of the as-synthesized Pd-NPs becomes smaller,compared with those in the absence of any surfactant(Pd-NP/MWCNT)or in the presence of an anionic surfactant SDS(Pd-NP/SDS-MWCNT)and a neutral surfactant OP(PdNP/OP-MWCNT).Results show that the MWCNTs modified with CTAB are propitious to the in situ reduction of Pd2?.Among the prepared catalysts,Pd-NP/CTABMWCNT displays the highest electroactivity for ethanol oxidation in alkaline media.
基金the support from Shanghai QingZhen Test Technology Co.,Ltd.,China (No.880772)Dalian Jin Dian Biotechnology Co.,Ltd.,China (No.880988)+5 种基金Anhui Chromatographic Instrument Co.,Ltd.,China (No.880511)the Key Project of Anhui Provincial Department of Education,China (No.2023AH051634)the Innovative Research Team of Undergraduates,China (Nos.S202110879087 and S202210879085)the Research Funds of Anhui Science and Technology University,China (No.FZ220179)the Foundation of Anhui Science and Technology University,China (No.HCWD202001)the Science and Technology Planning Project of Bengbu City,China (No.2022gx10)。
文摘Platinum-based nanocomposites have been considered as one of the most promising catalysts for methanol oxidation reactions(MORs), which yet still suffer from low electrochemical activity and electron-transfer properties. Apart from van-der-Waals heterostructures,herein, we report a novel nanocomposite with the structure of Pt–Ru bimetallic nanoparticles covalently-bonded onto multi-walled carbon nanotubes (MWCNTs)(Pt–Ru@MWCNT), which have been successfully fabricated via a facile and green synthesis method. It is demonstrated that the Pt–Ru@MWCNT nanocomposite possesses much enhanced electrocatalytic activity with the electrochemical active surface area(ECSA) of 110.4 m^(2)·g^(-1)for Pt towards MOR, which is 2.67 and 4.0 times higher than those of 20wt%commercial Pt@C and Pt-based nanocomposite prepared by other method, due to the improved electron-transfer properties originated from M–O–C covalent bonds. This work provides us a new strategy for the structural design of highly-efficient electrocatalysts in boosting MOR performance.
文摘A sensitive electroanalytical method for quantification of pheniramine in pharmaceutical formulation has been investigated on the basis of the enhanced electrochemical response at glassy carbon electrode modified with multi-walled carbon nanotubes in the presence of sodium lauryl sulfate.The experimental results suggest that the phcniramine in anionic surfactant solution exhibits electrocatalytic effect resulting in a marked enhancement of the peak current response.Peak current response is linearly dependent on the concentration of pheniramine in the range 200-1500 μg/mL with correlation coefficient 0.9987.The limit of detection is 58.31 μg/m L.The modified electrode shows good sensitivity and repeatability.
文摘This work proposes the synthesis of the 5%wt Ru on MWCNT catalyst and the influence of feed rate and testing variables for low-temperature oxidation affecting the CO<sub>2</sub> yield. Morphology and incorporation of the nanoparticles in carbon nanotubes were investigated by specific surface area (BET method);thermogravimetric analyses (TGA);X-ray diffraction;Raman spectroscopy, transmission electron microscopy (TEM) and XPS. The conversions of CO and O<sub>2</sub> were mostly 100% in groups C1 and C2 (temperature between 200 and 500<span style="white-space:nowrap;">°</span>C with low WHSV). In order to assess the effect of mass on catalytic activity, condition C3 was tested at even lower temperatures. In the tested catalyst, high activity (100% CO and O<sub>2</sub> conversion) was observed, keeping it active under reaction conditions, suggesting oxi-reduction of the RuO<sub>2</sub> at surface without affecting the MWCNT but Lewis acid influencing the CO<sub>2</sub> yield.
基金supported by the National Defense Science and Technology Innovation Zone Project (Nos. 17H863-05-ZT-002-040-001 and 18-H863-05-ZT-002-01301
文摘Improving the performance of anode is a crucial step for increasing output power of marine sediment microbial fuel cells(MSMFCs)to drive marine monitor to work for a long term on the ocean floor.A pyrolyzed iron phthalocyanine modified multi-walled carbon nanotubes composite(FePc/MWCNTs)has been utilized as a novel nodified anode in the MSMFC.Its structure of the composite modified anode and electrochemical performance have been investigated respectively in the paper.There is a substantial improvement in electron-transfer efficiency from the bacteria biofilm to the modified anode via the pyrolyzed FePc/MWCNTs composite based on their cyclic voltammetry(CV)and Tafel curves.The electron transfer kinetic activity of the FePc/MWCNTs-modified anode is 1.86 times higher than of the unmodified anode.The maximum power density of the modified MSMFC was 572.3±14 m W m^-2,which is 2.6 times larger than the unmodified one(218.3±11 m W m^-2).The anodic structure and cell scale would be greatly minimized to obtain the same output power by the modified MSMFC,so that it will make the MSMFC to be easily deployed on the remote ocean floor.Therefore,it would have a great significance for us to design a novel and renewable long term power source.Finally,a novel molecular synergetic mechanism is proposed to elucidate its excellent electrochemical performance.
基金supported by the Specialized Research Fund for the Doctoral Program of Higher Education(200800191013)the Fundamental Research Funds for the Central Universities
文摘Objective This study was aimed to investigate the toxic effects of 3 nanomaterials, i.e. multi-walled carbon nanotubes （MWCNTs）, graphene oxide （GO）, and reduced graphene oxide （RGO）, on zebrafish embryos. Methods The 2-h post-fertilization （hpf） zebrafish embryos were exposed to MWCNTs, GO, and RGO at different concentrations （1, 5, 10, 50, 100 mg/L） for 96 h. Afterwards, the effects of the 3 nanomateria on spontaneous movement, heart rate, hatching rate, length of larvae, mortality, and malformations Is were evaluated. Results Statistical analysis indicated that RGO significantly inhibited the hatching of zebrafish embryos. Furthermore, RGO and MWCNTs decreased the length of the hatched larvae at 96 hpf. No obvious morphological malformation or mortality was observed in the zebrafish embryos after exposure to the three nanomaterials. Conclusion MWCNTs, GO, and RGO were all toxic to zebrafish embryos to influence embryos hatching and larvae length. Although no obvious morphological malformation and mortality were observed in exposed zebrafish embryos, further studies on the toxicity of the three nanomaterials are still needed.
基金Supported by the National Natural Science Foundation of China(Nos.20676027 and 21076066)the Postdoctoral Foundation of Heilongjiang Province,China(No.LBH-Q07111)
文摘The electrocatalytic oxidation of nitric oxide（NO） at a glass carbon electrode（GC） modified with functionalized single-walled carbon nanotubes（SWCNTs） was investigated by cyclic voltammetry（CV） and electrochemical impedance spectroscopy（EIS）.It was found that the SWCNT modified electrode could speed greatly up the electron transfer rate compared with the bare GC electrode.After the SWCNT was treated with alkali or mixed acids,the reaction rate and activation energy of NO electrooxidation were changed to different extent.Chemical modification of the SWCNT surface is one of the most powerful methods to change the sensitivity of NO electrooxidation reaction.The modified electrode with SWCNT obtained by the firstly alkali treatment and then the mixed acids treatment was the best one for NO electrooxidation,the result of CV was also confirmed by that of EIS.The anodic processes of NO were recognized more clearly by exploring the reaction mechanism of NO electrooxidation at the SWCNT modified electrode.
文摘A new chemically modified electrode(CME) immobilized on the surface of multi-wall carbon nanotubes functionalized with carboxylic groups was fabricated. The results indicate that the CME exhibits efficiently electrocatalytic oxidation of 6-mercaptopurine(6-MP). The CME can be used as the working electrode in the liquid chromatography for the determination of 6-MP. The peak current of 6-MP is linearly changed with its concentration ranging from 4.0×10 -7 to 1.0×10 -4 mol/L with the calculated detection limit (S/N=3) of 2.0×10 -7 mol/L. Coupled with microdialysis sampling, the method has been successfully applied to assessing the content of 6-MP in rat blood.
文摘In this work, noncovalent functionalization of multiwalled carbon nanotube （MWNT） with acridine orange （AO） by electropolymerization is studied. The obtained composite film is a viable alternate electrode material, non-toxic, chemical inert, not volatile, using to construct modified electrode. The new type modified electrode has both of unique properties of MWNT and poly acridine orange （POAO）, can provide good sensitivity, low limits of detection, good response precision, and superb response stability.
文摘Acid-based purification process of multi-walled carbon nanotubes （MWNTs） produced via catalytic decomposition of methane with NiO/TiO2 as a catalyst is described. By combining the oxidation in air and the acid refluxes, the impurities, such as amorphous carbon, carbon nanoparticles, and the NiO/TiO2 catalyst, are eliminated. Scanning electron microscopy （SEM） and transmission electron microscopy （TEM） images confirm the removal of the impurities. The percentage of the carbon nanotubes purity was analyzed using thermal gravimetric analysis （TGA）. Using this process, 99.9 wt% purity of MWNTs was obtained.
基金supported by the National Natural Science Foundation of China(21576299,21576300)Guangzhou Science and Technology Project(201607010104,201707010079)+3 种基金Science and Technology Planning Project of Guangdong Province(2017A050501009)the National Key Research and Development Program of China(2016YFB0101204)Tip-top Scientific and Technical Innovative Youth Talents of Guangdong Special Support Program(2016TQ03N322)the fundamental Research Funds for Central Universities(17lgzd14)~~
文摘Hydrogen peroxide(H2O2)is a very useful chemical reagent,but the current industrial methods for its production suffer from serious energy consumption problems.Using high-activity and high-selectivity catalysts to electrocatalyze the oxygen reduction reaction(ORR)through a two-electron(2e^-)pathway is a very promising route to produce H2O2.In this work,we obtained partially oxidized multi-walled carbon nanotubes(MWCNTs)with controlled structure and composition by oxidation with concentrated sulfate and potassium permanganate at 40℃ for 1 h(O-CNTs-40-1).The outer layers of O-CNTs-40-1 are damaged with defects and oxygen-containing functional groups,while the inner layers are maintained intact.The optimized structure and composition of the partially oxidized MWCNTs ensure that O-CNTs-40-1 possesses both a sufficient number of catalytic sites and good conductivity.The results of rotating ring disk electrode measurements reveal that,among all oxidized MWCNTs,O-CNTs-40-1 shows the greatest improvement in hydrogen peroxide selectivity(from ~ 30% to ~ 50%)and electron transfer number(from ~ 3.4 to ~ 3.0)compared to those of the raw MWCNTs.The results of electrochemical impedance spectroscopy measurements indicate that both the charge-transfer and intrinsic resistances of O-CNTs-40-1 are lower than those of the raw MWCNTs and of the other oxidized MWCNTs.Finally,direct tests of the H2O2 production confirm the greatly improved catalytic activity of O-CNTs-40-1 relative to that of the raw MWCNTs.
基金supported partly by a grant from Shanghai Science and Technology Committee International Collaboration Program (Project No. 055207078)
文摘Objective To investigate in vitro cytotoxicity and oxidative stress response induced by multiwalled carbon nanotubes （MWCNTs）. Methods Cultured macrophages （murine RAW264.7 cells） and alveolar epithelium cells type II （human A549 lung cells） were exposed to the blank control, DNA salt control, and the MWCNTs suspensions at 2.5, 10, 25, and 100 ug/mL for 24 h. Each treatment was evaluated by cell viability, cytotoxicity and oxidative stress. Results Overall, both cell lines had similar patterns in response to the cytotoxicity and oxidative stress of MWCNTs. DNA salt treatment showed no change compared to the blank control. In both cell lines, significant changes at the doses of 25 and 100 ug/mL treatments were found in cell viabilities, cytotoxicity, and oxidative stress indexes. The reactive oxygen species （ROS） generation was also found to be significantly higher at the dose of 10 ug/mL treatment, whereas no change was seen in most of the indexes. The ROS generation in both cell lines went up in minutes, reached the climax within an hour and faded down after several hours. Conclusion Exposure to MWCNTs resulted in a dose-dependent cytotoxicity in cultured RAW264.7 cells and A549 cells, that was closely correlated to the increased oxidative stress.
基金supported by the Natural Science Foundation of Hubei Province (No.2009CDA050)the New Century Excellent Talents in University (No. NCET-10-0137)the National Natural Science Foundation of China (No. 51072143)
文摘The microstructural evolution and oxidation resistance of multi-walled carbon nanotubes （MWCNTs） by di- rectly heating silicon powder and MWCNTs in a coke bed from 1000 to 1500 ~C are investigated with the aid of X-ray diffraction （XRD）, scanning electron microscopy （SEM）, high resolution transmission electron microscopy （HRTEM） and thermogravimetry-differential scanning calorimetry （TG-DSC）. The results showed that the morphology and microstructure of MWCNTs did not change much after being treated from 1000 ~C to 1200 ~C. An obvious SiC coating was formed on the surface of MWCNTs from 1300 to 1400 ~C. Up to 1500 ~C, nearly all the MWCNTs transformed into SiC nanowires. The oxidation resistance of the treated MWCNTs was improved compared with as-received ones. Non-isothermal kinetics showed that the oxidation activation energy of the treated MWCNTs reached 208 kJ/mol, much higher than 264 k J/tool of as-received ones.
基金supported by the National Natural Science Foundation of China (21376279, 21276102, 21425627)Guangdong Technology Research Center for Synthesis and Separation of Thermosensitive Chemicals (2015B090903061)+1 种基金the Fundamental Research Funds for the Central Universities (14lgpy28)Guangzhou Science and Technology Plan Projects (2014J4100125)~~
文摘We have designed and prepared β-cyclodextrin （β-CD）-functionalized multi-walled nanotubes （MWCNTs-g-CD） for the oxidation of cinnamon oil to natural benzaldehyde under aqueous condi- tions. The synergistic effect of combining MWCNTs with β-CD led to a remarkable increase in the performance of the MWCNTs-g-CD for the catalytic oxidation of cinnamaldehyde, which exhibited 95% cinnamaldehyde conversion and 85% selectivity to natural benzaldehyde with a short reaction time of 10 rain. The MWCNTs-g-CD also exhibited outstanding recyclability with good stability, showing no discernible decrease in their catalytic activity over five reaction cycles.
基金supported by the National Natural Science Foundation of China (21035005)the Doctoral Program Foundation of Institutions of Higher Education of China (20115301120002)the Natural Science Foundation of Yunnan Province of China (2011FB007)
文摘Graphene possesses unique physical and chemical properties, which have inspired a wide range of potential biomedical applications. However, little is known about the adverse effects of graphene on the human body and ecological environment. The purpose of our work is to make assessment on the toxicity of graphene oxide (GO) against human cell line (human bone marrow neuroblastoma cell line and human epithelial carcinoma cell line) and zebrafish (Danio rerio) by comparing the toxic effects of GO with its sister, multi-walled carbon nanotubes (MWNTs). The results show that GO has a moderate toxicity to organisms since it can induce minor (about 20%) cell growth inhibition and slight hatching delay of zebrafish embryos at a dosage of 50 mg/L, but did not result in significant increase of apoptosis in embryo, while MWNTs exhibit acute toxicity leading to a strong inhibition of cell proliferation and serious morphological defects in developing embryos even at relatively low concentration of 25 mg/L. The distinctive toxicity of GO and MWNTs should be ascribed to the different models of interaction between nanomaterials and organisms, which arises from the different geometric structures of nanomaterials. Collectively, our work suggests that GO does actual toxicity to organisms posing potential environmental risks and the result is also shedding light on the geometrical structure-dependent toxicity of graphitic nanomaterials.
基金Project supported by the National Natural Science Foundation of China (No. 20373027) the Foundation for Scientists Returned from Abroad Di-rected under the State Ministry of Education of China the Natural Science Foundation of Education Committee of
文摘NADPH can be directly oxidized on a carbon nanotube modified glassy carbon (CNT/GC) electrode in phosphate buffer solution (pH=6.0) with a diminution of the overpotential of more than 700 mV. The anodic peak currents increase linearly with the increase of concentration of NADPH in the range of 5 x 10(-7) to 1 x 10(-3) mol/L with a detection limit of about 1 x 10-7 mol/L. The CNT/GC electrode exhibits high sensitivity, low potential and stability in detecting NADPH and thus might be used in biosensors to study the electrocatalytic reaction of important dehydrogenase-based biological systems.
文摘Multi-walled carbon nanotubes （MWCNTs） were fabricated and oxidized by different concentrations of sodium hypochlorite （NaOC1） solutions. The untreated MWCNTs and modified MWCNTs were employed as adsorbents to study their characterizations and adsorption performance of toluene, ethylbenzene and xylene isomers （TEX） in an aqueous solution. The physicochemical properties of MWCNTs were greatly affected after oxidation, which influences TEX adsorption capacity. The 3% NaOCl-oxidized MWCNTs shows the greatest enhancement in TEX adsorption, followed by the 30% NaOCl. More interestingly, the 15% NaOCl-oxidized MWCNTs has lower adsorption capacities than untreated MWCNTs. The adsorption mechanism of TEX on treated MWCNTs is attributed to the combined action of hydrophobic interaction, π-π bonding interaction between the aromatic ring of TEX and the oxygen-containing functional groups of MWCNTs and electrostatic interac- tion. 3% NaOCl solution could not only introduce much oxygen-containing functional groups on MWCNTs, but also lead to less damage for the pore structure. This suggests that the CNTs-3% NaOCl is efficient adsorbent for TEX and that they may possess good potential for TEX removal in wastewater treatment.
基金supported by the National Natural Science Foundation of China(Nos.51521006,51579095,51378190)Ecology and Environment Department of Hunan,the Program for Changjiang Scholars and Innovative Research Team in University(No.IRT-13R17)。
文摘Nanoparticles(NPs)are widely used for their special physical properties and released into the natural environment.When two types of NPs exist in the same environment,the presence of one type of NP may affect the properties of the other type of NP.This study investigated the toxic effects of multi-walled carbon nanotubes(MWCNTs)and copper oxide nanoparticles(Cu O NPs)on Tetradesmus obliquus.Both NPs had toxic effects on algae,and the toxic effects of MWCNTs were significantly stronger than Cu O NPs which the 96-hr median effective concentration to algae were 33.8 and 169.2 mg/L,respectively.Oxidative stress and cell membrane damage were the main reasons for the toxicity of NPs to algae,and they were concentration-dependent,and the existence of Cu O NPs in some groups reduced cell membrane damage caused by MWCNTs which may because that Cu O NPs formed heteroaggregation with MWCNTs,reducing the contact of nanoparticles with cell membranes,then reducing physical damage.Scanning electron microscopy(SEM)and transmission electron microscope(TEM)results indicated cell damage,the heteroaggregation of MWCNTs-Cu O NPs and obvious nanoparticles internalization.In some groups,the presence of Cu O NPs significantly reduced reactive oxygen species(ROS)level induced by MWCNTs.However,for the highest concentration group,the ROS level was much higher than that of the two NPs alone treatment groups,which might be related to the high concentration of MWCNTs promoting the internalization of Cu O NPs.MWCNTs and Cu O NPs affected and interacted with each other,causing more complex toxic effects on aquatic organisms.
基金supported by the strategic grant POSDRU/88/1.5/S/50783POSDRU/21/1.5/G/13798+1 种基金POSDRU/89/1.5/S/57649 co-financed by the European Social Fund - Investing in People,within the Sectoral Operational Programme Human Resources Development 2007-2013partially by the PN II-RU-PD129/2010 and PN II Ideas 165/2011
文摘This work describes the electrochemical behaviour of ibuprofen on two types of multi-walled carbon nanotubes based composite electrodes, i.e., multi-walled carbon nanotubes-epoxy （MWCNT） and silver-modified zeolite-multi-wailed carbon nanotubes-epoxy （AgZMWCNT） composites electrodes. The composite electrodes were obtained using two-roll mill procedure. SEM images of surfaces of the composites revealed a homogeneous distribution of the composite components within the epoxy matrix. AgZMWCNT composite electrode exhibited the better electrical conductivity and larger electroactive surface area. The electrochemical determination of ibuprofen （IBP） was achieved using AgZMWCNT by cyclic voltammetry, differential-pulsed voltammetry, square-wave voltammetry and chronoamperometry. The IBP degradation occurred on both composite electrodes under controlled electrolysis at 1.2 and 1.75 V vs. Ag/AgCl, and IBP concentration was determined comparatively by differential-pulsed voltammetry, under optimized conditions using AgZMWCNT electrode and UV-Vis spectrophotometry methods to determine the IBP degradation performance for each electrode. AgZMWCNT electrode exhibited a dual character allowing a double application in IBP degradation process and its control.
基金financially supported by the National Natural Science Foundation of China(Nos.21307142 and 21403261)Ningbo Science and Technology Bureau(No.2014D10004)
文摘The functionalization of multi-walled carbon nanotubes （MWCNTs） by ozone treatment has been sys- tematically investigated by using Raman spectroscopy, transmission electron microscopy （TEM）, Fourier transform inhared spectroscopy （FTIR）, X-ray photoelectron spectroscopy （XPS）, organic elemental anal- ysis （OEA） and Boehm titration. The results showed that the functionalization process occurred at defective sites （opened mouths, tube caps, debris, etc.） before opening caps and truncating walls, and finally the graphitic structure was deteriorated. The surface oxygen content first increased with the treatment time but kept at around 8.0 wt% after 5 h. The analysis of the distribution of oxygen-containing groups re- vealed that phenolic hydroxyl was gradually converted to carboxyl and lactone, The carboxyl was found to play a pivotal role to reduce the over-potentials when we used the functionalized MWCNTs as the cat- alyst for oxygen reduction reaction （ORR）.
