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Sample records for carbon nanotube electrodes

  1. Flexible carbon nanotubes electrode for neural recording.

    Science.gov (United States)

    Lin, Chia-Min; Lee, Yu-Tao; Yeh, Shih-Rung; Fang, Weileun

    2009-05-15

    This paper demonstrates a novel flexible carbon nanotubes (CNTs) electrode array for neural recording. In this device, the CNTs electrode arrays are partially embedded into the flexible Parylene-C film using a batch microfabrication process. Through this fabrication process, the CNTs can be exposed to increase the total sensing area of an electrode. Thus, the flexible CNTs electrode of low impedance is realized. In application, the flexible CNTs electrode has been employed to record the neural signal of a crayfish nerve cord for in vitro recording. The measurements demonstrate the superior performance of the presented flexible CNTs electrode with low impedance (11.07 kohms at 1 kHz) and high peak-to-peak amplitude action potential (about 410 microV). In addition, the signal-to-noise ratio (SNR) of the presented flexible CNTs electrode is about 257, whereas the SNR of the reference (a pair of Teflon-coated silver wires) is only 79. The simultaneous recording of the flexible CNTs electrode array is also demonstrated. Moreover, the flexible CNTs electrode has been employed to successfully record the spontaneous spikes from the crayfish nerve cord. The amplitude of the spontaneous peak-to-peak response is about 25 microV. PMID:19272765

  2. Voltammetric Response of Epinephrine at Carbon Nanotube Modified Glassy Carbon Electrode and Activated Glassy Carbon Electrode

    Institute of Scientific and Technical Information of China (English)

    WANG Juan; TANG Ping; ZHAO Fa-qiong; ZENG Bai-zhao

    2005-01-01

    The electrochemical behavior of epinephrine at activated glassy carbon electrode and carbon nanotube-coated glassy carbon electrode was studied. Epinephrine could exhibit an anodic peak at about 0.2 V (vs. SCE) at bare glassy carbon electrode, but it was very small.However, when the electrode was activated at certain potential (i. e. 1.9V) or modified with carbon nanotube, the peak became more sensitive,resulting from the increase in electrode area in addition to the electrostatic attraction. Under the selected conditions, the anodic peak current was linear to epinephrine concentration in the range of 3.3 × 10-7-1.1 × 10-5mol/L at activated glassy carbon electrode and in the range of 1.0 × 10-6-5.0 × 10-5 mol/L at carbon nanotube-coated electrode. The correlation coefficients were 0. 998 and 0. 997, respectively. The determination limit was 1.0 × 10-7 mol/L. The two electrodes have been successfully applied for the determination of epinephrine in adrenaline hydrochloride injection with recovery of 95%-104%.

  3. Electrochemical properties of double wall carbon nanotube electrodes

    Directory of Open Access Journals (Sweden)

    Pumera Martin

    2007-01-01

    Full Text Available AbstractElectrochemical properties of double wall carbon nanotubes (DWNT were assessed and compared to their single wall (SWNT counterparts. The double and single wall carbon nanotube materials were characterized by Raman spectroscopy, scanning and transmission electron microscopy and electrochemistry. The electrochemical behavior of DWNT film electrodes was characterized by using cyclic voltammetry of ferricyanide and NADH. It is shown that while both DWNT and SWNT were significantly functionalized with oxygen containing groups, double wall carbon nanotube film electrodes show a fast electron transfer and substantial decrease of overpotential of NADH when compared to the same way treated single wall carbon nanotubes.

  4. Carbon Nanotube Electrodes for Effective Interfacing with Retinal Tissue

    OpenAIRE

    Shoval, Asaf; Adams, Christopher; David-Pur, Moshe; Shein, Mark; Hanein, Yael; Sernagor, Evelyne

    2009-01-01

    We have investigated the use of carbon nanotube coated microelectrodes as an interface material for retinal recording and stimulation applications. Test devices were micro-fabricated and consisted of 60, 30 μm diameter electrodes at spacing of 200 μm. These electrodes were coated via chemical vapor deposition of carbon nanotubes, resulting in conducting, three dimensional surfaces with a high interfacial area. These attributes are important both for the quality of the cell-surface coupling as...

  5. Carbon nanotube electrodes for effective interfacing with retinal tissue

    Directory of Open Access Journals (Sweden)

    Asaf Shoval

    2009-04-01

    Full Text Available We have investigated the use of carbon nanotube microelectrodes as an interface material for retinal recording and stimulation applications. Test devices were micro-fabricated and consisted of 60 pristine 30 um electrodes coated with chemical vapor deposited carbon nanotubes, resulting in conducting, three dimensional surfaces with a high effective interfacial area. These attributes are important both for the quality of the cell-surface coupling as well as for electro-chemical interfacing efficiency. The entire chip was packaged to fit a commercial multielectrode recording and stimulation system. Electrical recordings of spontaneous spikes from whole-mount neonatal mouse retinas were consistently obtained minutes after retinas were placed over the electrodes, exhibiting typical bursting and propagating waves. Most importantly, the signals obtained with carbon nanotube electrodes have exceptionally high signal to noise ratio, reaching values as high as 75. Moreover, spikes are marked by a conspicuous gradual increase in amplitude recorded over a period of minutes to hours, suggesting improvement in cell-electrode coupling. This phenomenon is not observed in conventional commercial electrodes. Electrical stimulation using carbon nanotube electrodes was also achieved. We attribute the superior performances of the carbon nanotube electrodes to their three dimensional nature and the strong neuro-carbon nanotube affinity. The results presented here show the great potential of carbon nanotube electrodes for retinal interfacing applications. Specifically, our results demonstrate a route to achieve a reduction in the electrode size down to few micrometers in order to achieve high efficacy local stimulation needed in retinal prosthetic devices.

  6. Supercapacitor Electrodes from Activated Carbon Monoliths and Carbon Nanotubes

    Science.gov (United States)

    Dolah, B. N. M.; Othman, M. A. R.; Deraman, M.; Basri, N. H.; Farma, R.; Talib, I. A.; Ishak, M. M.

    2013-04-01

    Binderless monoliths of supercapacitor electrodes were prepared by the carbonization (N2) and activation (CO2) of green monoliths (GMs). GMs were made from mixtures of self-adhesive carbon grains (SACG) of fibers from oil palm empty fruit bunches and a combination of 5 & 6% KOH and 0, 5 & 6% carbon nanotubes (CNTs) by weight. The electrodes from GMs containing CNTs were found to have lower specific BET surface area (SBET). The electrochemical behavior of the supercapacitor fabricated using the prepared electrodes were investigated by electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge (GCD). In general an addition of CNTs into the GMs reduces the equivalent series resistance (ESR) value of the cells. A cell fabricated using electrodes from GM with 5% CNT and 5% KOH was found to have the largest reduction of ESR value than that from the others GMs containing CNT. The cell has steeper Warburg's slope than that from its respective non-CNT GM, which reflect the smaller resistance for electrolyte ions to move into pores of electrodes despite these electrodes having largest reduction in specific BET surface area. The cell also has the smallest reduction of specific capacitance (Csp) and maintains the specific power range despite a reduction in the specific energy range due to the CNT addition.

  7. Carbon Nanotubes as Electrodes for Dielectrophoresis of DNA

    OpenAIRE

    Tuukkanen, Sampo; Toppari, J. Jussi; Kuzyk, Anton; Hirviniemi, Lasse; Hytonen, Vesa P.; Ihalainen, Teemu; Torma, Paivi

    2006-01-01

    Dielectrophoresis can potentially be used as an efficient trapping tool in the fabrication of molecular devices. For nanoscale objects, however, the Brownian motion poses a challenge. We show that the use of carbon nanotube electrodes makes it possible to apply relatively low trapping voltages and still achieve high enough field gradients for trapping nanoscale objects, e.g., single molecules. We compare the efficiency and other characteristics of dielectrophoresis between carbon nanotube ele...

  8. Carbon nanotube electrodes for effective interfacing with retinal tissue

    OpenAIRE

    Asaf Shoval; Christopher Adams; Moshe David-Pur; MArk Shein; Yael Hanein; Evelyne Sernagor

    2009-01-01

    We have investigated the use of carbon nanotube microelectrodes as an interface material for retinal recording and stimulation applications. Test devices were micro-fabricated and consisted of 60 pristine 30 um electrodes coated with chemical vapor deposited carbon nanotubes, resulting in conducting, three dimensional surfaces with a high effective interfacial area. These attributes are important both for the quality of the cell-surface coupling as well as for electro-chemical interfacing eff...

  9. Density controlled carbon nanotube array electrodes

    Science.gov (United States)

    Ren, Zhifeng F.; Tu, Yi

    2008-12-16

    CNT materials comprising aligned carbon nanotubes (CNTs) with pre-determined site densities, catalyst substrate materials for obtaining them and methods for forming aligned CNTs with controllable densities on such catalyst substrate materials are described. The fabrication of films comprising site-density controlled vertically aligned CNT arrays of the invention with variable field emission characteristics, whereby the field emission properties of the films are controlled by independently varying the length of CNTs in the aligned array within the film or by independently varying inter-tubule spacing of the CNTs within the array (site density) are disclosed. The fabrication of microelectrode arrays (MEAs) formed utilizing the carbon nanotube material of the invention is also described.

  10. Enhanced Growth and Redox Characteristics of Some Conducting Polymers on Carbon Nanotube Modified Electrodes

    Institute of Scientific and Technical Information of China (English)

    R.Saraswathi

    2007-01-01

    1 Results Recent studies on the electrochemistry of a number of active compounds at carbon nanotube electrodes have proved beyond doubt their excellent electrocatalytic properties.Particularly,the advancements accomplished towards the functionalization of carbon nanotubes resulting in their enhanced solubilization in aqueous solutions have helped in the preparation of stable carbon nanotube electrodes.Glassy carbon has been invariably the preferred substrate for casting carbon nanotube electrodes.Such c...

  11. Fabrication, Characterization and Electrocatalysis of an Ordered Carbon Nanotube Electrode

    Institute of Scientific and Technical Information of China (English)

    陈静; 包建春; 蔡称心

    2003-01-01

    A method for fabrication of ordered carbon nanotube (CNT) film,which was template-synthesized within the highly ordered pores of a commercially available alumina template membrane,modified glassy carbon(CNT/GC) electrode was established.The CNT/GC electrode showed excellent electrocatalytic activity toward dopamine electrochemical reaction without introducing any electrochemically active group into CNT film or activating any electrochemically active group into CNT film or activating the electrode electrochemically.DA undergoes ideal reversible electrochemical reaction on CNT/GC electrode at low scan rate(≤20mV/s) with an excellent reproducibility and stability.The CNT/GC electrode might be used in biosensors because the highly ordered CNT may present a steric effect on more efficient redox reactions of biomolecules.

  12. Electrical breakdown gas detector featuring carbon nanotube array electrodes.

    Science.gov (United States)

    Kim, Seongyul; Pal, Sunil; Ajayan, Pulickel M; Borca-Tasciuc, Theodorian; Koratkar, Nikhil

    2008-01-01

    We demonstrate here detection of dichloro-difluoro-methane and oxygen in mixtures with helium using a carbon nanotube electrical breakdown sensor device. The sensor is comprised of an aligned array of multiwalled carbon nanotubes deposited on a nickel based super-alloy (Inconel 600) as the anode; the counter electrode is a planar nickel sheet. By monitoring the electrical breakdown characteristics of oxygen and dichloro-difluoro-methane in a background of helium, we find that the detection limit for dichloro-difluoro-methane is approximately 0.1% and the corresponding limit for oxygen is approximately 1%. A phenomenologigal model is proposed to describe the trends observed in detection of the two mixtures. These results indicate that carbon nanotube based electrical breakdown sensors show potential as end detectors in gas-chromatography devices. PMID:18468093

  13. Flexible supercapacitor yarns with coaxial carbon nanotube network electrodes

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Fabricated flexible yarn supercapacitor with coaxial electrodes. • Use of multifunctional carbon nanotube network electrodes eliminates inactive components and enables high energy/power density. • Robust structure maintains >95% of energy/power while under deformation. - Abstract: Flexible supercapacitors with a yarn-like geometry were fabricated with coaxially arranged electrodes. Carbon nanotube (CNT) network electrodes enabled the integration of the electronic conductor and active material of each electrode into a single component. CNT yarns were employed as the inner electrode to provide the supporting structure of the device. These part integration strategies eliminated the need for inactive material, which resulted in device volumetric energy and power densities among the highest reported for flexible carbon-based EDLCs. In addition, the coaxial yarn cell design provided a robust structure able to undergo flexural deformation with minimal impact on the energy storage performance. Greater than 95% of the energy density and 99% of the power density were retained when wound around an 11 cm diameter cylinder. The electrochemical properties were characterized at stages throughout the fabrication process to provide insights and potential directions for further development of these novel cell designs

  14. Carbon-Nanotube-Based Electrodes for Biomedical Applications

    Science.gov (United States)

    Li, Jun; Meyyappan, M.

    2008-01-01

    A nanotube array based on vertically aligned nanotubes or carbon nanofibers has been invented for use in localized electrical stimulation and recording of electrical responses in selected regions of an animal body, especially including the brain. There are numerous established, emerging, and potential applications for localized electrical stimulation and/or recording, including treatment of Parkinson s disease, Tourette s syndrome, and chronic pain, and research on electrochemical effects involved in neurotransmission. Carbon-nanotube-based electrodes offer potential advantages over metal macroelectrodes (having diameters of the order of a millimeter) and microelectrodes (having various diameters ranging down to tens of microns) heretofore used in such applications. These advantages include the following: a) Stimuli and responses could be localized at finer scales of spatial and temporal resolution, which is at subcellular level, with fewer disturbances to, and less interference from, adjacent regions. b) There would be less risk of hemorrhage on implantation because nano-electrode-based probe tips could be configured to be less traumatic. c) Being more biocompatible than are metal electrodes, carbon-nanotube-based electrodes and arrays would be more suitable for long-term or permanent implantation. d) Unlike macro- and microelectrodes, a nano-electrode could penetrate a cell membrane with minimal disruption. Thus, for example, a nanoelectrode could be used to generate an action potential inside a neuron or in proximity of an active neuron zone. Such stimulation may be much more effective than is extra- or intracellular stimulation via a macro- or microelectrode. e) The large surface area of an array at a micron-scale footprint of non-insulated nanoelectrodes coated with a suitable electrochemically active material containing redox ingredients would make it possible to obtain a pseudocapacitance large enough to dissipate a relatively large amount of electric charge

  15. Field emission properties of the graphenated carbon nanotube electrode

    Energy Technology Data Exchange (ETDEWEB)

    Zanin, H., E-mail: hudson.zanin@bristol.ac.uk [School of Chemistry, University of Bristol, Bristol BS8 1TS (United Kingdom); Faculdade de Engenharia Elétrica e Computação, Departamento de Semicondutores, Instrumentos e Fotônica, Universidade Estadual de Campinas, UNICAMP, Av. Albert Einstein N. 400, CEP 13 083-852 Campinas, São Paulo (Brazil); Ceragioli, H.J.; Peterlevitz, A.C.; Baranauskas, Vitor [Faculdade de Engenharia Elétrica e Computação, Departamento de Semicondutores, Instrumentos e Fotônica, Universidade Estadual de Campinas, UNICAMP, Av. Albert Einstein N. 400, CEP 13 083-852 Campinas, São Paulo (Brazil); Marciano, F.R.; Lobo, A.O. [Laboratory of Biomedical Nanotechnology/Institute of Research and Development at UNIVAP, Av. Shishima Hifumi, 2911, CEP 12244-000 Sao Jose dos Campos, SP (Brazil)

    2015-01-01

    Graphical abstract: - Highlights: • Facile method to prepare graphenated carbon nanotubes (g-CNTs). • The electric field emission behaviour of g-CNTs was studied. • g-CNTs show better emission current stability than non-graphenated CNTs. - Abstract: Reduced graphene oxide-coated carbon nanotubes (RGO-CNT) electrodes have been prepared by hot filament chemical vapour deposition system in one-step growth process. We studied RGO-CNT electrodes behaviour as cold cathode in field emission test. Our results show that RGO-CNT retain the low threshold voltage typical of CNTs, but with greatly improved emission current stability. The field emission enhancement value is significantly higher than that expected being caused by geometric effect (height divided by the radius of nanotube). This suggested that the field emission of this hybrid structure is not only from a single tip, but eventually it is from several tips with contribution of graphene nanosheets at CNT's walls. This phenomenon explains why the graphenated carbon nanotubes do not burn out as quickly as CNT does until emission ceases completely. These preliminaries results make nanocarbon materials good candidates for applications as electron sources for several devices.

  16. ELECTROANALYTICAL APPLICATIONS OF CARBOXYL-MODIFIED CARBON NANOTUBE FILM ELECTRODES

    Institute of Scientific and Technical Information of China (English)

    C.G. Hu; W.L. Wang; K.J. Liao; W. Zhu

    2003-01-01

    The electrochemical behavior of a carboxyl-modified carbon nanotube films was investigated to explore its possibility in electroanalytical applicaton. Cyclic voltammetry of quinone was conducted in 1mol/L Na2SO4, which showed a stable, quasi-reversible voltammetric response for quinone / hydroquinone, and the anodic and the cathodic peak potentials were 0.657V and -0.029V (vs. SCE) at a scan rate of 0.1V.s-1, respectively. Both anodic and cathodic peak currents depended linearly on the square root of the scan rate over the range of 0.01-0. 5 V.s-1, which suggested that the process of the electrode reactions was diffusion-controlled. Carboxyl-modified carbon nanotube electrodes made it possible to determine low level of dopamine selectively in the presence of a large excess of ascorbic acid in acidic media using derivative voltammetry.The results obtained were discussed in details. This work demonstrates the potential of carboxyl-modified carbon nanotube electrodes for electroanalytical applications.

  17. Carbon nanotube prepared from carbon monoxide by CVD method and its application as electrode materials

    Institute of Scientific and Technical Information of China (English)

    AN Yuliang; YUAN Xia; CHENG Shinan; GEN Xin

    2006-01-01

    Carbon nanotubes with larger inner diameter were synthesized by the chemical vapor deposition of carbon monoxide (CO) on iron catalyst using H2S as promoting agent.It is found that the structure and morphology of carbon nanotubes can be tailored, to some degree, by varying the experimental conditions such as precursor components and process parameters.The results show that the presence of H2S may play key role for growing Y-branched carbon nanotubes.The products were characterized by SEM, TEM, and Raman spectroscopy, respectively.Furthermore, the obtained carbon nanotubes were explored as electrode materials for supercapacitor.

  18. Effects of binders on the performance of electric double-layer capacitors of carbon nanotube electrodes

    Institute of Scientific and Technical Information of China (English)

    LI Chensha; WANG Dazhi; ZHANG Baoyou; WANG Xiaofeng; CAO Maosheng; LIANG Ji

    2005-01-01

    Polarizable electrodes of electric double layer capacitor (EDLCs) were made from carhon nanotubes. Effects of different binders, which are phenolic resin (PF) and polytetrafluoroethylene (PTFE), on the properties of polarizable electrodes are studied. Results indicate that the microstructure, pore size distribution and specific capacitance of the electrodes with PTFE binder are superior to those electrodes with PF binder after carbonization. The suitable binder (PTFE) for carbon nanotubes electrodes is proposed.

  19. Single-wall carbon nanotube chemical attachment at platinum electrodes

    Science.gov (United States)

    Rosario-Castro, Belinda I.; Contés-de-Jesús, Enid J.; Lebrón-Colón, Marisabel; Meador, Michael A.; Scibioh, M. Aulice; Cabrera, Carlos R.

    2010-11-01

    Self-assembled monolayer (SAM) techniques were used to adsorb 4-aminothiophenol (4-ATP) on platinum electrodes in order to obtain an amino-terminated SAM as the base for the chemical attachment of single-wall carbon nanotubes (SWCNTs). A physico-chemical, morphological and electrochemical characterizations of SWCNTs attached onto the modified Pt electrodes was done by using reflection-absorption infrared spectroscopy (RAIR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and cyclic voltammetry (CV) techniques. The SWNTs/4-ATP/Pt surface had regions of small, medium, and large thickness of carbon nanotubes with heights of 100-200 nm, 700 nm to 1.5 μm, and 1.0-3.0 μm, respectively. Cyclic voltammetries (CVs) in sulfuric acid demonstrated that attachment of SWNTs on 4-ATP/Pt is markedly stable, even after 30 potential cycles. CV in ruthenium hexamine was similar to bare Pt electrodes, suggesting that SWNTs assembly is similar to a closely packed microelectrode array.

  20. Using a cut-paste method to prepare a carbon nanotube fur electrode

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, H; Cao, G P; Yang, Y S [Research Institute of Chemical Defense, West building, No. 35 Huayuanbeilu Road, Beijing 100083 (China)

    2007-05-16

    We describe and realize an aligned carbon nanotube array based 'carbon nanotube fur (CNTF)' electrode. We removed an 800 {mu}m long aligned carbon nanotube array from the silica substrate, and then pasted the array on a nickel foam current collector to obtain a CNTF electrode. CNTF's characteristics and electrochemical properties were studied systemically in this paper. The cut-paste method is simple, and does not damage the microstructure of the aligned carbon nanotube array. The CNTF electrode obtained a specific capacitance of 14.1 F g{sup -1} and excellent rate capability.

  1. Using a cut paste method to prepare a carbon nanotube fur electrode

    Science.gov (United States)

    Zhang, H.; Cao, G. P.; Yang, Y. S.

    2007-05-01

    We describe and realize an aligned carbon nanotube array based 'carbon nanotube fur (CNTF)' electrode. We removed an 800 µm long aligned carbon nanotube array from the silica substrate, and then pasted the array on a nickel foam current collector to obtain a CNTF electrode. CNTF's characteristics and electrochemical properties were studied systemically in this paper. The cut-paste method is simple, and does not damage the microstructure of the aligned carbon nanotube array. The CNTF electrode obtained a specific capacitance of 14.1 F g-1 and excellent rate capability.

  2. Using a cut-paste method to prepare a carbon nanotube fur electrode

    International Nuclear Information System (INIS)

    We describe and realize an aligned carbon nanotube array based 'carbon nanotube fur (CNTF)' electrode. We removed an 800 μm long aligned carbon nanotube array from the silica substrate, and then pasted the array on a nickel foam current collector to obtain a CNTF electrode. CNTF's characteristics and electrochemical properties were studied systemically in this paper. The cut-paste method is simple, and does not damage the microstructure of the aligned carbon nanotube array. The CNTF electrode obtained a specific capacitance of 14.1 F g-1 and excellent rate capability

  3. Single-walled Carbon Nanotubes as Electrode Materials for Supercapacitors

    Institute of Scientific and Technical Information of China (English)

    XU Bina; WU Feng; WANG Fang; CHEN Shi; CAO Gao-Ping; YANG Yu-Sheng

    2006-01-01

    Large-scale synthesized single-walled carbon nanotubes (SWNT) prepared by electric arc discharge method and a mixture of NiO and Y2O3 as catalyst have been used as electrode materials for supercapacitors. N2 adsorption/desorption measurement shows that the SWNT is a microporous and mesoporous material with specific surface area 435 m2g1.Thespecific capacitance of the nitric acid treated SWNT in aqueous electrolyte reaches as high as 105 F/g, which is a combination of electric double layer capacitance and pseudocapacitance. The SWNT-based capacitors also have good charge/discharge reversibility and cycling perdurability.

  4. Copper-decorated carbon nanotubes-based composite electrodes for nonenzymatic detection of glucose

    OpenAIRE

    Pop, A.(National Institute for Physics and Nuclear Engineering, Bucharest, Romania); Manea, F.; Orha, C.; Motoc, S.; Llinoiu, E.; Vaszilcsin, N.; Schoonman, J.

    2012-01-01

    The aim of this study was to prepare three types of multiwall carbon nanotubes (CNT)-based composite electrodes and to modify their surface by copper electrodeposition for nonenzymatic oxidation and determination of glucose from aqueous solution. Copper-decorated multiwall carbon nanotubes composite electrode (Cu/CNT-epoxy) exhibited the highest sensitivity to glucose determination.

  5. Highly conductive interwoven carbon nanotube and silver nanowire transparent electrodes

    Directory of Open Access Journals (Sweden)

    Andrew J Stapleton, Rakesh A Afre, Amanda V Ellis, Joe G Shapter, Gunther G Andersson, Jamie S Quinton and David A Lewis

    2013-01-01

    Full Text Available Electrodes fabricated using commercially available silver nanowires (AgNWs and single walled carbon nanotubes (SWCNTs produced sheet resistances in the range 4–24 Ω squ−1 with specular transparencies up to 82 %. Increasing the aqueous dispersibility of SWCNTs decreased the bundle size present in the film resulting in improved SWCNT surface dispersion in the films without compromising transparency or sheet resistance. In addition to providing conduction pathways between the AgNW network, the SWCNTs also provide structural support, creating stable self-supporting films. Entanglement of the AgNWs and SWCNTs was demonstrated to occur in solution prior to deposition by monitoring the transverse plasmon resonance mode of the AgNWs during processing. The interwoven AgNW/SWCNT structures show potential for use in optoelectronic applications as transparent electrodes and as an ITO replacement.

  6. All-Carbon Electrode Consisting of Carbon Nanotubes on Graphite Foil for Flexible Electrochemical Applications

    Directory of Open Access Journals (Sweden)

    Je-Hwang Ryu

    2014-03-01

    Full Text Available We demonstrate the fabrication of an all-carbon electrode by plasma-enhanced chemical vapor deposition for use in flexible electrochemical applications. The electrode is composed of vertically aligned carbon nanotubes that are grown directly on a flexible graphite foil. Being all-carbon, the simple fabrication process and the excellent electrochemical characteristics present an approach through which high-performance, highly-stable and cost-effective electrochemical applications can be achieved.

  7. Asymmetric electrochemical supercapacitor, based on polypyrrole coated carbon nanotube electrodes

    International Nuclear Information System (INIS)

    Highlights: • Polypyrrole (PPy) coated multiwalled carbon nanotubes (MWCNT) were prepared. • New method is based on the use of new electrochemically active dopants for PPy. • The dopans provided dispersion of MWCNT and promoted PPy coating formation. • Symmetric PPy–MWCNT supercapacitors showed high capacitance and low resistance. • Asymmetric PPy–MWCNT/VN–MWCNT devices and modules allowed larger voltage window. - Abstract: Conductive polypyrrole (PPy) polymer – multiwalled carbon nanotubes (MWCNT) composites were synthesized using sulfanilic acid azochromotrop (SPADNS) and sulfonazo III sodium salt (CHR-BS) as anionic dopants for chemical polymerization of PPy. The composites were tested for application in electrodes of electrochemical supercapacitors (ES). Sedimentation tests, electrophoretic deposition experiments and Fourier transform infrared spectroscopy (FTIR) investigations showed that strong adsorption of anionic CHR-BS on MWCNT provided MWCNT dispersion. The analysis of scanning and transmission electron microscopy data demonstrated that the use of CHR-BS allowed the formation of PPy coatings on MWCNT. As a result, the composites, prepared using CHR-BS, showed higher capacitance, compared to the composites, prepared using SPADNS. The electrodes, containing MWCNT, coated with PPy showed a capacitance of 179 F g−1 for active mass loading of 10 mg cm−2, good capacitance retention at scan rates in the range of 2–100 mV s−1 and excellent cyclic stability. Asymmetric ES devices, containing positive PPy–MWCNT electrodes and negative vanadium nitride (VN)–MWCNT electrodes showed significant improvement in energy storage performance, compared to the symmetric ES due to the larger voltage window. The low impedance and high capacitance of the individual cells paved the way to the development of modules with higher voltage, which showed good electrochemical performance

  8. Carbon nanotube/felt composite electrodes without polymer binders

    Energy Technology Data Exchange (ETDEWEB)

    Rosolen, J. Mauricio; Matsubara, E.Y.; Marchesin, Marcel S.; Lala, Stella M.; Montoro, L.A.; Tronto, S. [Departamento de Quimica-FFCLRP, Universidade de Sao Paulo, Ribeirao Preto 14040-930, SP (Brazil)

    2006-11-08

    In this work we have investigated the suitability of composite electrodes consisting of cup-stacked and bamboo-like carbon nanotubes (CNT) synthesized directly onto a carbon felt for both lithium storage and double-layer capacitance applications. The CNT/felt composite electrode was prepared using catalytic chemical vapor decomposition on the carbon felt. The microstructure of the electrodes was characterized by scanning electron microscopy. Electrochemical characterization of the CNT/felt, either submitted or not to acid treatment for extraction of the catalytic particles used during the CNT growth, was carried out using 1molL{sup -1} LiPF{sub 6} in mixtures of ethylene carbonate, dimethyl carbonate, diethyl carbonate, and propylene carbonate. The carbon nanotubes loading and the type of CNT, whether open or closed, on the felt were the most significant factors regarding the electrochemical properties of the composite. With respect to the application of the composite to lithium storage, an anomalous behavior in the reversible specific capacity as a function of the current was detected. The capacity was found to be large at higher current values. The best reversible specific capacity was found for the open-CNT/felt (275mAhg{sup -1} at 0.16Ag{sup -1}, and 200mAhg{sup -1} at 0.82Ag{sup -1}), on an area of 0.634mm{sup 2}. The double-layer capacitance of the CNT decreased with increasing current. In the case of the open-CNT with a CNT loading of 13.93mg, the composite provided 40.3{mu}Fcm{sup 2} or about 12Fg{sup -1} at 10mA of polarization current using 1molL{sup -1} LiPF{sub 6} in mixtures of ethylene carbonate and dimethyl carbonate. For the closed-CNT with a CNT loading of 9.3mg, the double-layer capacitance was 30Fg{sup -1} at 20mA in 1M H{sub 2}SO{sub 4}. (author)

  9. Polymer-Assisted Direct Deposition of Uniform Carbon Nanotube Bundle Networks for High Performance Transparent Electrodes

    KAUST Repository

    Hellstrom, Sondra L.

    2009-06-23

    Flexible transparent electrodes are crucial for touch screen, flat panel display, and solar cell technologies. While carbon nanotube network electrodes show promise, characteristically poor dispersion properties have limited their practicality. We report that addition of small amounts of conjugated polymer to nanotube dispersions enables straightforward fabrication of uniform network electrodes by spin-coating and simultaneous tuning of parameters such as bundle size and density. After treatment in thionyl chloride, electrodes have sheet resistances competitive with other reported carbon nanotube based transparent electrodes to date. © 2009 American Chemical Society.

  10. Polymer-assisted direct deposition of uniform carbon nanotube bundle networks for high performance transparent electrodes.

    Science.gov (United States)

    Hellstrom, Sondra L; Lee, Hang Woo; Bao, Zhenan

    2009-06-23

    Flexible transparent electrodes are crucial for touch screen, flat panel display, and solar cell technologies. While carbon nanotube network electrodes show promise, characteristically poor dispersion properties have limited their practicality. We report that addition of small amounts of conjugated polymer to nanotube dispersions enables straightforward fabrication of uniform network electrodes by spin-coating and simultaneous tuning of parameters such as bundle size and density. After treatment in thionyl chloride, electrodes have sheet resistances competitive with other reported carbon nanotube based transparent electrodes to date. PMID:19422197

  11. Composite electrode of carbon nanotubes and vitreous carbon for electron field emission

    OpenAIRE

    Matsubara, EY; Rosolen, JM; Silva, SRP

    2008-01-01

    In this work, the electron field emission behaviour of electrodes formed by carbon nanotubes (CNTs) grown onto monolithic vitreous carbon (VCarbon) substrates with microcavities is presented. Scanning electron microscopy was used to characterize the microstructure of the films. Tungsten probes, stainless steel sphere, and phosphor electrodes were employed in the electron field emission study. The CNT/VCarbon composite represents a route to inexpensive excellent large area electron emission ca...

  12. Electroadsorption Desalination with Carbon Nanotube/PAN-Based Carbon Fiber Felt Composites as Electrodes

    OpenAIRE

    2014-01-01

    The chemical vapor deposition method is used to prepare CNT (carbon nanotube)/PCF (PAN-based carbon fiber felt) composite electrodes in this paper, with the surface morphology of CNT/PCF composites and electroadsorption desalination performance being studied. Results show such electrode materials with three-dimensional network nanostructures having a larger specific surface area and narrower micropore distribution, with a huge number of reactive groups covering the surface. Compared with PCF ...

  13. Study on electroactive and electrocatalytic surfaces of single walled carbon nanotube-modified electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Salinas-Torres, David [Departamento de Quimica Fisica and Instituto Universitario de Materiales de Alicante, Universidad de Alicante, Apdo. de Correos 99, E-03080 Alicante (Spain); Huerta, Francisco [Departamento de Ingenieria Textil y Papelera, Universidad Politecnica de Valencia, Plaza Ferrandiz y Carbonell, 1. E-03801 Alcoy (Spain); Montilla, Francisco, E-mail: francisco.montilla@ua.e [Departamento de Quimica Fisica and Instituto Universitario de Materiales de Alicante, Universidad de Alicante, Apdo. de Correos 99, E-03080 Alicante (Spain); Morallon, Emilia [Departamento de Quimica Fisica and Instituto Universitario de Materiales de Alicante, Universidad de Alicante, Apdo. de Correos 99, E-03080 Alicante (Spain)

    2011-02-01

    An investigation of the electrocatalysis of single-walled carbon nanotubes modified electrodes has been performed in this work. Nanotube-modified electrodes present a surface area much higher than the bare glassy carbon surfaces as determined by capacitance measurements. Several redox probes were selected for checking the reactivity of specific sites at the carbon nanotube surface. The presence of carbon nanotubes on the electrode improves the kinetics for all the reactions studied compared with the bare glassy carbon electrode with variations of the heterogeneous electron transfer rate constant up to 5 orders of magnitude. The most important effects are observed for the benzoquinone/hydroquinone and ferrocene/ferricinium redox couples, which show a remarkable improvement of their electron transfer kinetics on SWCNT-modified electrodes, probably due to strong {pi}-{pi} interaction between the organic molecules and the walls of the carbon nanotubes. For many of the reactions studied, less than 1% of the nanotube-modified electrode surface is transferring charge to species in solution. This result suggests that only nanotube tips are active sites for the electron transfer in such cases. On the contrary, the electroactive surface for the reactions of ferrocene and quinone is higher indicating that the electron transfer is produced also from the nanotube walls.

  14. SELECTIVE VOLTAMMETRIC DETERMINATION OF HYDROXYPURINS ON ELECTRODE MODIFIED BY CARBON NANOTUBES

    OpenAIRE

    Shaidarova, L. G.; Chelnokova, I. A.; Mahmutova, G. F.; Degteva, M. A.; Gedmina, A. V.; Budnikov, H. C.

    2014-01-01

    Carbon nanotubes (CNT) deposited on the surface of glassy carbon electrode show catalytic activity in the oxidation of uric acid, xanthine and hypoxanthine that is exhibited in decreasing overvoltage and increasing oxidation current of hydroxypurins. The method of simultaneous voltammetric determination of uric acid, xanthine and hypoxanthine at the electrode modified by carbon nanotubes is suggested. The linear dependence of analytical signal from substrates concentration is observed in the ...

  15. Electrodes from carbon nanotubes/NiO nanocomposites synthesized in modified Watts bath for supercapacitors

    Science.gov (United States)

    Hakamada, Masataka; Abe, Tatsuhiko; Mabuchi, Mamoru

    2016-09-01

    A modified Watts bath coupled with pulsed current electroplating is used to uniformly deposit ultrafine nickel oxide particles (diameter carbon nanotubes. The capacitance of the multiwalled carbon nanotubes/nickel oxide electrodes was as high as 2480 F g-1 (per mass of nickel oxide), which is close to the theoretical capacitance of NiO.

  16. Copper-decorated carbon nanotubes-based composite electrodes for nonenzymatic detection of glucose

    NARCIS (Netherlands)

    Pop, A.; Manea, F.; Orha, C.; Motoc, S.; Llinoiu, E.; Vaszilcsin, N.; Schoonman, J.

    2012-01-01

    The aim of this study was to prepare three types of multiwall carbon nanotubes (CNT)-based composite electrodes and to modify their surface by copper electrodeposition for nonenzymatic oxidation and determination of glucose from aqueous solution. Copper-decorated multiwall carbon nanotubes composite

  17. A Multiwall Carbon Nanotube-chitosan Modified Electrode for Selective Detection of Dopamine in the Presence of Ascorbic Acid

    Institute of Scientific and Technical Information of China (English)

    Ling Yan JIANG; Chuan Yin LIU; Li Ping JIANG; Guang Han LU

    2005-01-01

    A novel multiwall carbon nanotube-chitosan modified electrode has been prepared.The modified electrode resolves the overlapping voltammetric response of dopamine and ascorbic acid into two well-defined peak by 212 mY. The mechanism of discrimination of dopamine from ascorbic acid is discussed. Dopamine can be determined selectively with the carbon nanotube-chitosan modified electrode. The electrode shows good sensitivity, selectivity and stability.keywords: Nanotube-chitosan modified electrode, dopamine, ascorbic acid.

  18. Anthocyanin-sensitized solar cells using carbon nanotube films as counter electrodes

    Science.gov (United States)

    Zhu, Hongwei; Zeng, Haifeng; Subramanian, Venkatachalam; Masarapu, Charan; Hung, Kai-Hsuan; Wei, Bingqing

    2008-11-01

    Carbon nanotube (CNT) films have been used as counter electrodes in natural dye-sensitized (anthocyanin-sensitized) solar cells to improve the cell performance. Compared with conventional cells using natural dye electrolytes and platinum as the counter electrodes, cells with a single-walled nanotube (SWNT) film counter electrode show comparable conversion efficiency, which is attributed to the increase in short circuit current density due to the high conductivity of the SWNT film.

  19. Anthocyanin-sensitized solar cells using carbon nanotube films as counter electrodes

    International Nuclear Information System (INIS)

    Carbon nanotube (CNT) films have been used as counter electrodes in natural dye-sensitized (anthocyanin-sensitized) solar cells to improve the cell performance. Compared with conventional cells using natural dye electrolytes and platinum as the counter electrodes, cells with a single-walled nanotube (SWNT) film counter electrode show comparable conversion efficiency, which is attributed to the increase in short circuit current density due to the high conductivity of the SWNT film.

  20. Carbon nanotube macrofilm-based nanocomposite electrodes for energy applications

    Science.gov (United States)

    Cao, Zeyuan

    Finding new electrode materials for energy conversion and storage devices have been the focus of recent research in the fields of science and engineering. Suffering from poor electronic conductivity, chemical and mechanical stability, active electrode materials are usually coupled with different carbon nanostructured materials to form nanocomposite electrodes, showing promising electrochemical performance. Among the carbon nanostructured materials, carbon nanotube (CNT) macrofilms draw great attention owing to their extraordinary properties, such as a large specific surface area, exceptionally high conductivity, porous structure, flexibility, mechanical robustness, and adhesion. They could effectively enhance the electrochemical performance of the incorporated active materials in the nanocomposites. In this dissertation, CNT macrofilm-based nanocomposites are investigated for rechargeable lithium-ion batteries, supercapacitors, and electrocatalysts of fuel cells. The progressive research developed various nanocomposites from cathode materials to anode materials followed by a general nanocomposite solution due to the unique adhesive property of the fragmented CNT macrofilms. The in-situ synthesis strategy are explored to in-situ deposit unlithiated cathode materials V2O5 and lithiated cathode materials LiMn2O4 nanocrystals in the matrix of the CNT macrofilms as nanocomposites to be paired with metallic lithium in half cells. The presence of oxygen-containing functional groups on the surface of the CNT macrofilms after purification can enhance the association with the active materials to enable the facilitated transport of solvated ions to the electrolyte/electrode interfaces and increase the diffusion kinetics, consequently enhancing the battery performance in terms of high specific capacity, rate capability, and cycling stability. It is also significant to demonstrate a reliable, low-cost, and effective route to synthesize the family of metal oxides (MxOy (M=Fe, Co

  1. Relation between the composition and properties of carbon nanotubes paste electrodes (CNTPEs)

    Czech Academy of Sciences Publication Activity Database

    Mikysek, T.; Stočes, M.; Švancara, I.; Ludvík, Jiří

    Pardubice : Univerzita Pardubice, 2010, s. 69-75. ISBN 978-80-7395-348-5 R&D Projects: GA MŠk(CZ) LC06035; GA MŠk LC510 Institutional research plan: CEZ:AV0Z40400503 Keywords : carbon nanotube paste electrode * carbon paste electrode * characterization Subject RIV: CG - Electrochemistry

  2. Carbon Nanotube Electrodes for Hot-Wire Electrochemistry

    Czech Academy of Sciences Publication Activity Database

    Gründler, P.; Frank, Otakar; Kavan, Ladislav; Dunsch, L.

    2009-01-01

    Roč. 10, č. 3 (2009), s. 559-563. ISSN 1439-4235 R&D Projects: GA AV ČR IAA400400804; GA AV ČR KAN200100801 Institutional research plan: CEZ:AV0Z40400503 Keywords : electrochemistry * electrodes * nanotubes * Raman spectroscopy Subject RIV: CG - Electrochemistry Impact factor: 3.453, year: 2009

  3. Nanostructured membranes and electrodes with sulfonic acid functionalized carbon nanotubes

    KAUST Repository

    Tripathi, Bijay Prakash

    2011-02-01

    Herein we report the covalent functionalization of multiwall carbon nanotubes by grafting sulfanilic acid and their dispersion into sulfonated poly(ether ether ketone). The nanocomposites were explored as an option for tuning the proton and electron conductivity, swelling, water and alcohol permeability aiming at nanostructured membranes and electrodes for application in alcohol or hydrogen fuel cells and other electrochemical devices. The nanocomposites were extensively characterized, by studying their physicochemical and electrochemical properties. They were processed as self-supporting films with high mechanical stability, proton conductivity of 4.47 × 10 -2 S cm-1 at 30 °C and 16.8 × 10-2 S cm-1 at 80 °C and 100% humidity level, electron conductivity much higher than for the plain polymer. The methanol permeability could be reduced to 1/20, keeping water permeability at reasonable values. The ratio of bound water also increases with increasing content of sulfonated filler, helping in keeping water in the polymer in conditions of low external humidity level. © 2010 Elsevier B.V.

  4. Resistive random access memory enabled by carbon nanotube crossbar electrodes.

    Science.gov (United States)

    Tsai, Cheng-Lin; Xiong, Feng; Pop, Eric; Shim, Moonsub

    2013-06-25

    We use single-walled carbon nanotube (CNT) crossbar electrodes to probe sub-5 nm memory domains of thin AlOx films. Both metallic and semiconducting CNTs effectively switch AlOx bits between memory states with high and low resistance. The low-resistance state scales linearly with CNT series resistance down to ∼10 MΩ, at which point the ON-state resistance of the AlOx filament becomes the limiting factor. Dependence of switching behavior on the number of cross-points suggests a single channel to dominate the overall characteristics in multi-crossbar devices. We demonstrate ON/OFF ratios up to 5 × 10(5) and programming currents of 1 to 100 nA with few-volt set/reset voltages. Remarkably low reset currents enable a switching power of 10-100 nW and estimated switching energy as low as 0.1-10 fJ per bit. These results are essential for understanding the ultimate scaling limits of resistive random access memory at single-nanometer bit dimensions. PMID:23705675

  5. Electrocatalysis of oxygen reduction on nitrogen-containing multi-walled carbon nanotube modified glassy carbon electrodes

    International Nuclear Information System (INIS)

    Highlights: ► Pyrolysis in the presence of urea was used for nitrogen doping of carbon nanotubes. ► N-doped carbon nanotubes were used as catalysts for the oxygen reduction reaction. ► N-doped carbon material showed a high catalytic activity for ORR in alkaline media. ► N-containing CNT material is an attractive cathode catalyst for alkaline membrane fuel cells. - Abstract: The electrochemical reduction of oxygen was studied on nitrogen-doped multi-walled carbon nanotube (NCNT) modified glassy carbon (GC) electrodes employing the rotating disk electrode (RDE) method. Nitrogen doping was achieved by simple pyrolysis of the carbon nanotube material in the presence of urea. The surface morphology and composition of the NCNT samples were investigated by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The SEM images revealed a rather uniform distribution of NCNTs on the GC electrode substrate. The XPS analysis showed a successful doping of carbon nanotubes with nitrogen species. The RDE results revealed that in alkaline solution the N-doped nanotube materials showed a remarkable electrocatalytic activity towards oxygen reduction. At low overpotentials the reduction of oxygen followed a two-electron pathway on undoped carbon nanotube modified GC electrodes, whereas on NCNT/GC electrodes a four-electron pathway of O2 reduction predominated. The results obtained are significant for the development of nitrogen-doped carbon-based cathodes for alkaline membrane fuel cells.

  6. Large scale inkjet-printing of carbon nanotubes electrodes for antioxidant assays in blood bags

    OpenAIRE

    Lesch, Andreas; Cortes Salazar, Fernando; Prudent, Michel; Delobel, Julien; Rastgar, Shokoufeh; Lion, Niels; Tissot, Jean-Daniel; Tacchini, Philippe; Girault, Hubert H.

    2014-01-01

    Herein, we present the large scale fabrication of carbon nanotubes (CNT) electrodes supported on flexible polymeric sheets by subsequent multilayer inkjet printing of a silver layer for electrical connection, CNT layers as active electrode material and an insulation layer to define a stand-alone CNT active electrode area with high accuracy. Optical and electrochemical characterization using several redox mediators demonstrates the reproducibility of the electrode surfaces and their functional...

  7. Enzymatic electrodes nanostructured with functionalized carbon nanotubes for biofuel cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Nazaruk, E.; Bilewicz, R. [University of Warsaw, Faculty of Chemistry, Warsaw (Poland); Sadowska, K.; Biernat, J.F. [Gdansk University of Technology, Chemical Faculty, Gdansk (Poland); Rogalski, J. [Maria Curie Sklodowska University, Department of Biochemistry, Lublin (Poland); Ginalska, G. [Medical University of Lublin, Department of Biochemistry, Lublin (Poland)

    2010-10-15

    Nanostructured bioelectrodes were designed and assembled into a biofuel cell with no separating membrane. The glassy carbon electrodes were modified with mediator-functionalized carbon nanotubes. Ferrocene (Fc) and 2,2{sup '}-azino-bis (3-ethylbenzothiazoline-6-sulfonate) diammonium salt (ABTS) bound chemically to the carbon nanotubes were found useful as mediators of the enzyme catalyzed electrode processes. Glucose oxidase from Aspergillus niger AM-11 and laccase from Cerrena unicolor C-139 were incorporated in a liquid-crystalline matrix-monoolein cubic phase. The carbon nanotubes-nanostructured electrode surface was covered with the cubic phase film containing the enzyme and acted as the catalytic surface for the oxidation of glucose and reduction of oxygen. Thanks to the mediating role of derivatized nanotubes the catalysis was almost ten times more efficient than on the GCE electrodes: catalytic current of glucose oxidation was 1 mA cm{sup -2} and oxygen reduction current exceeded 0.6 mA cm{sup -2}. The open circuit voltage of the biofuel cell was 0.43 V. Application of carbon nanotubes increased the maximum power output of the constructed biofuel cell to 100 {mu}W cm{sup -2} without stirring of the solution which was ca. 100 times more efficient than using the same bioelectrodes without nanotubes on the electrode surface. (orig.)

  8. Amperometric biosensor based on glassy carbon electrode modified with long-length carbon nanotube and enzyme

    Science.gov (United States)

    Furutaka, Hajime; Nemoto, Kentaro; Inoue, Yuki; Hidaka, Hiroki; Muguruma, Hitoshi; Inoue, Hitoshi; Ohsawa, Tatsuya

    2016-05-01

    An amperometric biosensor based on a glassy carbon electrode modified with long-length multiwalled carbon nanotubes (MWCNTs) and enzyme nicotinamide-adenine-dinucleotide-dependent glucose dehydrogenase (GDH) is presented. We demonstrate the effect of the MWCNT length on the amperometric response of the enzyme biosensor. The long length of MWCNT is 200 µm (average), whereas the normal length of MWCNT is 1 µm (average). The response of the long MWCNT–GDH electrode is 2 times more sensitive than that of the normal-length MWCNT–GDH electrode in the concentration range from 0.25–35 mM. The result of electrochemical impedance spectroscopy measurements suggest that the long-length MWCNT–GDH electrode formed a better electron transfer network than the normal-length one.

  9. Electrochemical oxidation and nanomolar detection of acetaminophen at a carbon-ceramic electrode modified by carbon nanotubes: A comparison between multi walled and single walled carbon nanotubes

    International Nuclear Information System (INIS)

    Carbon-ceramic electrodes (CCE) modified with carbon nanotubes were prepared, and the electrochemical behavior towards acetaminophen (ACOP) was investigated using both a bare CCE and electrodes modified with either single walled carbon nanotubes (SWCNT) or multi walled carbon nanotubes (MWCNT) in an effort to understand which of them is the better choice in terms of electrocatalyzing the oxidation of ACOP, and thus for sensing it. The SWCNT are found to be the better material in significantly enhancing the oxidation peak current and improving the reversibility of the oxidation. Under optimal conditions, linearity between the oxidation peak current and the concentration of ACOP is obtained for the concentration range from 40 nM to 85 μM, with a detection limit of 25 nM. Finally, ACOP was successfully determined with the SWCNT modified electrode in pharmaceutical samples. (author)

  10. Theoretical Simulation on the Assembly of Carbon Nanotubes Between Electrodes by AC Dielectrophoresis

    OpenAIRE

    Yang Liu; Lu Yang; Chen Changxin; Zhang Yafei

    2008-01-01

    Abstract The assembly of single-walled carbon nanotubes (SWCNTs) using the AC dielectrophoresis technique is studied theoretically. It is found that the comb electrode bears better position control of SWCNTs compared to the parallel electrode. In the assembly, when some SWCNTs bridge the electrode first, they can greatly alter the local electrical field so as to “screen off” later coming SWCNTs, which contributes to the formation of dispersed SWCNT array. The screening distance sc...

  11. Assembly of Carbon Nanotubes between Electrodes by Utilizing Optically Induced Dielectrophoresis and Dielectrophoresis

    OpenAIRE

    Gwo-Bin Lee; Pei-Fang Wu

    2011-01-01

    This study reports a new approach for assembling carbon nanotubes (CNTs) between electrodes combination of optically induced dielectrophoresis force and dielectrophoresis force. Metal electrodes and amorphous silicon layer were first patterned and then used to assemble CNTs. By utilizing moving light patterns, the CNTs could be collected to the central area between two metal electrodes. The CNTs with different concentrations can be collected and aligned to form CNTs lines with different width...

  12. Fabrication and electrochemical properties of carbon nanotube array electrode for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Qiao Ling Chen; Kuan Hong Xue; Wei Shen; Fei Fei Tao; Shou Yin Yin; Wen Xu [Nanjing Normal University (China). Chemistry Dept.

    2004-09-30

    The multiwalled carbon nanotube (MWNT) array was fabricated by chemical vapor deposition (CVD) in the template of porous alumina from the carbonaceous source of C{sub 2H}2 in the presence of a catalyst of ferric metals. To utilize the external surface other than the inner surface of the carbon nanotubes, 1 mol/L sulfuric acid was applied to remove off the most part of AAO template on the carbon nanotube electrode. The electrochemical performances of the carbon nanotube array electrode were investigated by use of the cyclic voltammetry, galvanostatic charge/discharge and ac impedance methods for its application in supercapacitors. The specific capacitance of 365 F/g of the electrode was achieved with the discharge current density of 210 mA/g in the solution of 1 mol/L H{sub 2}SO{sub 4}. In addition, the carbon nanotube array electrode was found to have low equivalent series resistance (ESR) and good cycling stability. (author)

  13. Composite electrodes of activated carbon derived from cassava peel and carbon nanotubes for supercapacitor applications

    Science.gov (United States)

    Taer, E.; Iwantono, Yulita, M.; Taslim, R.; Subagio, A.; Salomo, Deraman, M.

    2013-09-01

    In this paper, a composite electrode was prepared from a mixture of activated carbon derived from precarbonization of cassava peel (CP) and carbon nanotubes (CNTs). The activated carbon was produced by pyrolysis process using ZnCl2 as an activation agent. A N2 adsorption-desorption analysis for the sample indicated that the BET surface area of the activated carbon was 1336 m2 g-1. Difference percentage of CNTs of 0, 5, 10, 15 and 20% with 5% of PVDF binder were added into CP based activated carbon in order to fabricate the composite electrodes. The morphology and structure of the composite electrodes were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The SEM image observed that the distribution of CNTs was homogeneous between carbon particles and the XRD pattern shown the amorphous structure of the sample. The electrodes were fabricated for supercapacitor cells with 316L stainless steel as current collector and 1 M sulfuric acid as electrolyte. An electrochemical characterization was performed by using an electrochemical impedance spectroscopy (EIS) method using a Solatron 1286 instrument and the addition of CNTs revealed to improve the resistant and capacitive properties of supercapacitor cell.

  14. Electrochemical Reduction of Oxygen on Multi-walled Carbon Nanotubes Electrode in Alkaline Solution

    Institute of Scientific and Technical Information of China (English)

    You Qun CHU; Chun An MA; Feng Ming ZHAO; Hui HUANG

    2004-01-01

    The multi-walled carbon nanotubes (MWNTs) electrode was constructed using poly- tetrafluoroethylene as binder, and the electrochemical reductive behavior of oxygen in alkaline solution was first examined on this electrode. Compared with other carbon materials, MWNTs show higher electrocatalytic activity, and the reversibility of O2 reduction reaction is greatly improved. The experiments reveal that the electrochemical reduction of O2 to HO2- is controlled by adsorption. The preliminary results illustrate the potential application of MWNTs in fuel cells.

  15. Carbon felt supported carbon nanotubes catalysts composite electrode for vanadium redox flow battery application

    Science.gov (United States)

    Wei, Guanjie; Jia, Chuankun; Liu, Jianguo; Yan, Chuanwei

    2012-12-01

    A modified electrode for vanadium redox flow battery (VRFB) has been developed in this paper. The electrode is based on a traditional carbon felt (CF) grafted with the short-carboxylic multi-walled carbon nanotubes (MWCNTs). The microstructure and electrochemical property of the modified electrode as well as the performance of the VRFB single cell with it have been characterized. The results show that the MWCNTs are evenly dispersed and adhere to the surface of carbon fibres in the CF. The electrochemical activities of the modified CF electrode have been improved dramatically and the reversibility of the VO2+/VO2+ and V3+/V2+ redox couples increased greatly. The VRFB single cell with the modified CF exhibits higher coulombic efficiency (93.9%) and energy efficiency (82.0%) than that with the pristine CF. The SEM analysis shows that the MWCNTs still cohere with carbon fibres after charge and discharge test, indicating the stability of the MWCNTs in flowing electrolyte. Therefore, the composite electrode presents considerable potential for the commercial application of CF in VRFB.

  16. Development of electrochemical oxidase biosensors based on carbon nanotube-modified carbon film electrodes for glucose and ethanol

    OpenAIRE

    Gouveia-Caridade, Carla; Pauliukaite, Rasa; Brett, Christopher M. A.

    2008-01-01

    Functionalised multi-walled carbon nanotubes (MWCNTs) were cast on glassy carbon (GC) and carbon film electrodes (CFE), and were characterised electrochemically and applied in a glucose-oxidase-based biosensor. MWCNT-modified carbon film electrodes were then used to develop an alcohol oxidase (AlcOx) biosensor, in which AlcOx-BSA was cross-linked with glutaraldehyde and attached by drop-coating. The experimental conditions, applied potential and pH, for ethanol monitoring were optimised, and ...

  17. Electrooxidation of DNA at glassy carbon electrodes modified with multiwall carbon nanotubes dispersed in polyethylenimine

    International Nuclear Information System (INIS)

    This work reports the electrochemical response of the complex between dsDNA and PEI formed in solution and at the surface of glassy carbon electrodes (GCE) modified with a dispersion of multi-walled carbon nanotubes in polyethylenimine (CNT-PEI). Scanning Electron Microscopy and Scanning Electrochemical Microscopy demonstrate that the dispersion covers the whole surface of the electrode although there are areas with higher density of CNT and, consequently, with higher electrochemical reactivity. The adsorption of DNA at GCE/CNT-PEI is fast and it is mainly driven by electrostatic forces. A clear oxidation signal is obtained either for dsDNA or a heterooligonucleotide of 21 bases (oligoY) at potentials smaller than those for the oxidation at bare GCE. The comparison of the behavior of DNA before and after thermal treatment demonstrated that the electrochemical response highly depends on the 3D structure of the nucleic acid.

  18. Electrochemical Determination of Glycoalkaloids Using a Carbon Nanotubes-Phenylboronic Acid Modified Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Huiying Wang

    2013-11-01

    Full Text Available A versatile strategy for electrochemical determination of glycoalkaloids (GAs was developed by using a carbon nanotubes-phenylboronic acid (CNTs-PBA modified glassy carbon electrode. PBA reacts with α-solanine and α-chaconine to form a cyclic ester, which could be utilized to detect GAs. This method allowed GA detection from 1 μM to 28 μM and the detection limit was 0.3 μM. Affinity interaction of GAs and immobilized PBA caused an essential change of the peak current. The CNT-PBA modified electrodes were sensitive for detection of GAs, and the peak current values were in quite good agreement with those measured by the sensors.

  19. Electrochemical sensor for Baicalein using a carbon paste electrode doped with carbon nanotubes

    International Nuclear Information System (INIS)

    We report on the voltammetric determination of the flavonoid Baicalein by using a carbon paste electrode that was doped with multi-walled carbon nanotubes. The resulting sensor exhibits excellent redox activity towards Baicalein due to the large surface area and good conductivity of the electrode. Cyclic voltammetry at various scan rates was used to investigate the redox properties of Baicalein. At the optimum conditions, the sensor displays a linear current response to Baicalein in the 0.02-10 μM concentration range, with a limit of detection of 4.2 n M. The method was successfully applied to the determination of Baicalein in spiked human blood serum samples and in a Chinese oral liquid. (author)

  20. Electrochemical investigation of NO at single-wall carbon nanotubes modified electrodes

    Indian Academy of Sciences (India)

    Tingliang Xia; Hongmei Bi; Keying Shi

    2010-05-01

    The NO electro-oxidation was investigated at various single-wall carbon nanotubes (SWCNTs) modified electrodes by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Compared with the glassy carbon electrode, the SWCNTs modified electrodes possess higher electro-catalytic activity to NO electro-oxidation. CV results indicate that the peak current density of NO electro-oxidation at the SWCNT-COOH (SWCNTs with carboxyl groups) modified electrode is the highest and the peak potential is the most negative among the four kinds of electrodes. EIS indicates that the charge transfer resistance of NO electro-oxidation at the SWCNT-COOH modified electrode is the least. The determined factors (charge transfer and mass transfer of diffusion) of NO electro-oxidation are different in varied potential region. The mechanism of NO electro-oxidation reaction at the SWCNTs modified electrodes is also discussed.

  1. Effect of acid oxidization of carbon nanotube electrode on the capacitances of double layer capacitors

    Institute of Scientific and Technical Information of China (English)

    LI; Chensha; WANG; Dazhi; LIANG; Tongxiang; WANG; Xiaofen

    2004-01-01

    Polarizable electrode of electric double layer capacitor was made from carbon nanotubes. The effect of acid oxidation of electrode on the specific capacitance was studied. Oxidation removed the redundant carbon, expanded the pore size and introduced some kinds of functional groups on the surface of CNTs. The specific capacit ance of the electrodes with organic electrolyte was increased from 21.4 to 49.6 F/gafter being oxidized at a volume ratio of H2SO4 to HNO3 of 3:1.

  2. Fabrication and electrical properties of single wall carbon nanotube channel and graphene electrode based transistors arrays

    Energy Technology Data Exchange (ETDEWEB)

    Seo, M.; Kim, H.; Kim, Y. H.; Yun, H.; McAllister, K.; Lee, S. W., E-mail: leesw@konkuk.ac.kr [Division of Quantum Phases and Devices, School of Physics, Konkuk University, Seoul 143-701 (Korea, Republic of); Na, J.; Kim, G. T. [School of Electrical Engineering, Korea University, Seoul 136-701 (Korea, Republic of); Lee, B. J.; Kim, J. J.; Jeong, G. H. [Department of Nano Applied Engineering, Kangwon National University, Kangwon-do 200-701 (Korea, Republic of); Lee, I.; Kim, K. S. [Department of Physics and Graphene Research Institute, Sejong University, Seoul 143-747 (Korea, Republic of)

    2015-07-20

    A transistor structure composed of an individual single-walled carbon nanotube (SWNT) channel with a graphene electrode was demonstrated. The integrated arrays of transistor devices were prepared by transferring patterned graphene electrode patterns on top of the aligned SWNT along one direction. Both single and multi layer graphene were used for the electrode materials; typical p-type transistor and Schottky diode behavior were observed, respectively. Based on our fabrication method and device performances, several issues are suggested and discussed to improve the device reliability and finally to realize all carbon based future electronic systems.

  3. Fabrication and electrical properties of single wall carbon nanotube channel and graphene electrode based transistors arrays

    International Nuclear Information System (INIS)

    A transistor structure composed of an individual single-walled carbon nanotube (SWNT) channel with a graphene electrode was demonstrated. The integrated arrays of transistor devices were prepared by transferring patterned graphene electrode patterns on top of the aligned SWNT along one direction. Both single and multi layer graphene were used for the electrode materials; typical p-type transistor and Schottky diode behavior were observed, respectively. Based on our fabrication method and device performances, several issues are suggested and discussed to improve the device reliability and finally to realize all carbon based future electronic systems

  4. A Novel Cholesterol Oxidase Biosensor Based on Pt-nanoparticle /Carbon Nanotube Modified Electrode

    Institute of Scientific and Technical Information of China (English)

    Qiao Cui SHI; Tu Zhi PENG

    2005-01-01

    A Pt-nanoparticle/carbon nanotube modified graphite electrode immobilized with cholesterol oxidase/sol-gel layer was developed for monitoring cholesterol. Using this electrode,cholesterol concentration (4.0×10-6 to 1.0×10 mol/L) could be determined accurately in the presence of ascorbic or uric acid, and the response time was rapid (< 20 s). This biosensor has high sensitivity and selectivity.

  5. Carbon nanotube/Co3O4 composite for air electrode of lithium-air battery

    OpenAIRE

    Yoon, Taek Han; Park, Yong Joon

    2012-01-01

    A carbon nanotube [CNT]/Co3O4 composite is introduced as a catalyst for the air electrode of lithium-air [Li/air] batteries. Co3O4 nanoparticles are successfully attached to the sidewall of the CNT by a hydrothermal method. A high discharge capacity and a low overvoltage indicate that the CNT/Co3O4 composite is a very promising catalyst for the air electrode of Li/air batteries.

  6. Large magnetoresistance in single-walled carbon nanotubes contacted different ferromagnetic metal electrodes

    International Nuclear Information System (INIS)

    Magnetoresistance (MR) in single-walled carbon nanotubes (SWNTs) with different ferromagnetic source and drain electrodes (iron and cobalt) which have different coercivity was studied. Large MR ratio of 20% could be obtained at 8 K, while 1∼2% small MR ratio could be observed for the sample with the same ferromagnetic source and drain electrodes of Co. The MR ratio of 20% is very close to the theoretically predicted value of 26% for Co-Fe system

  7. First-principles study of high-conductance DNA sequencing with carbon nanotube electrodes

    OpenAIRE

    Sanvito, Stefano; RUNGGER, IVAN

    2012-01-01

    Rapid and cost-effective DNA sequencing at the single nucleotide level might be achieved by measuring a transverse electronic current as single-stranded DNA is pulled through a nanometer-sized pore. In order to enhance the electronic coupling between the nucleotides and the electrodes and hence the current signals, we employ a pair of single-walled close-ended (6,6) carbon nanotubes (CNTs) as electrodes. We then investigate the electron transport properties of nucleotides sandwich...

  8. Fabrication of Functionalized Carbon Nanotube Buckypaper Electrodes for Application in Glucose Biosensors

    OpenAIRE

    Henry Papa; Melissa Gaillard; Leon Gonzalez; Jhunu Chatterjee

    2014-01-01

    A highly sensitive glucose detection method was developed using functionalized carbon nanotube buckypaper as a free standing electrode in an electrochemical biosensor. Glucose oxidase was immobilized onto various buckypaper samples in order to oxidize glucose resulting in a measureable current/voltage signal output of the biosensor. Cyclic voltammetry (CV) and amperometry were utilized to determine the sensitivity of these buckypaper electrodes. Sensors of three different types of buckypaper ...

  9. Progress towards high-power Li/CFx batteries: electrode architectures using carbon nanotubes with CFx.

    Science.gov (United States)

    Zhang, Qing; Takeuchi, Kenneth J; Takeuchi, Esther S; Marschilok, Amy C

    2015-09-21

    Carbon monofluoride (CFx) has a high energy density, exceeding 2000 W h kg(-1), yet its application in primary lithium batteries is limited by its power capability. Multi-walled carbon nanotubes (CNTs) are appealing additives for high-power batteries, due to their outstanding electronic transport properties, high aspect ratio necessitating low volume fraction for percolation, and high tensile strength. This perspective describes the current state of the art in lithium-carbon monofluoride (Li/CFx) batteries and highlights the opportunities for the development of high-power Li/CFx batteries via utilization of carbon nanotubes. In this report, we generated several electrode architectures using CFx/CNT combinations, and demonstrated the effectiveness of CNTs in enhancing the rate capability and energy density of Li/CFx batteries. First, we investigated the resistivity of CFx combined with CNTs and compared the CFx/CNT composites with conventional carbon additives. Second, we built CFx-CNT electrodes without metallic current collectors using CNTs as substrates, and compared their electrochemical performance with conventional CFx electrodes using aluminum foil as a current collector. Furthermore, we fabricated multi-layered CNT-CFx-CNT composite electrodes (sandwich electrodes) and studied the impact of the structure on the performance of the electrode. Our work demonstrates some of the opportunities for utilization of CNTs in CFx electrodes and the resultant implementation of CFx as a battery cathode in next-generation high-power batteries. PMID:26280394

  10. Compressed multiwall carbon nanotube composite electrodes provide enhanced electroanalytical performance for determination of serotonin

    International Nuclear Information System (INIS)

    Serotonin (5-HT) is an important neurochemical that is present in high concentrations within the intestinal tract. Carbon fibre and boron-doped diamond based electrodes have been widely used to date for monitoring 5-HT, however these electrodes are prone to fouling and are difficult to fabricate in certain sizes and geometries. Carbon nanotubes have shown potential as a suitable material for electroanalytical monitoring of 5-HT but can be difficult to manipulate into a suitable form. The fabrication of composite electrodes is an approach that can shape conductive materials into practical electrode geometries suitable for biological environments. This work investigated how compression of multiwall carbon nanotubes (MWCNTs) epoxy composite electrodes can influence their electroanalytical performance. Highly compressed composite electrodes displayed significant improvements in their electrochemical properties along with decreased internal and charge transfer resistance, reproducible behaviour and improved batch to batch variability when compared to non-compressed composite electrodes. Compression of MWCNT epoxy composite electrodes resulted in an increased current response for potassium ferricyanide, ruthenium hexaammine and dopamine, by preferentially removing the epoxy during compression and increasing the electrochemical active surface of the final electrode. For the detection of serotonin, compressed electrodes have a lower limit of detection and improved sensitivity compared to non-compressed electrodes. Fouling studies were carried out in 10 μM serotonin where the MWCNT compressed electrodes were shown to be less prone to fouling than non-compressed electrodes. This work indicates that the compression of MWCNT carbon-epoxy can result in a highly conductive material that can be moulded to various geometries, thus providing scope for electroanalytical measurements and the production of a wide range of analytical devices for a variety of systems

  11. Carbon nanotube modification of microbial fuel cell electrodes.

    Science.gov (United States)

    Yazdi, Alireza Ahmadian; D'Angelo, Lorenzo; Omer, Nada; Windiasti, Gracia; Lu, Xiaonan; Xu, Jie

    2016-11-15

    The use of carbon nanotubes (CNTs) for energy harvesting devices is preferable due to their unique mechanical, thermal, and electrical properties. On the other hand, microbial fuel cells (MFCs) are promising devices to recover carbon-neutral energy from the organic matters, and have been hindered with major setbacks towards commercialization. Nanoengineered CNT-based materials show remarkable electrochemical properties, and therefore have provided routes towards highly effective modification of MFC compartments to ultimately reach the theoretical limits of biomass energy recovery, low-cost power production, and thus the commercialization of MFCs. Moreover, these CNT-based composites offer significant flexibility in the design of MFCs that enable their use for a broad spectrum of applications ranging from scaled-up power generation to medically related devices. This article reviews the recent advances in the modification of MFCs using CNTs and CNT-based composites, and the extent to which each modification route impacts MFC power and current generation. PMID:27213269

  12. Enhancing the capacitances of electric double layer capacitors based on carbon nanotube electrodes by carbon dioxide activation and acid oxidization

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Polarizable electrodes of electric double layer capacitors(EDLCs) were made from carbon nanotubes(CNTs).Effect of carbon dioxide activation together with acid oxidation for the electrodes on the characteristics and performances of electrodes and EDLCs was studied.Carbon dioxide activation changed the microstructure of the electrodes,increased the effective surface area of CNTs and optimized the distribution of apertures of the electrodes.Acid oxidization modified the surface characteristics of CNTs.Based on the polarizable electrodes treated by carbon dioxide activation and acid oxidization,the performances of EDLCs were greatly enhanced.The specific capacitance of the electrodes with organic electrolyte was increased from 21.8 F/g to 60.4 F/g.

  13. Design and Manufacture of Silver-Selective Electrode Based on Single-Walled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Khoorshid Mehdizadeh

    2015-06-01

    Full Text Available The present research explores the design and manufacture of coated ion-selective membranes on graphite electrodes with selectivity towards silver cations.Single- walled carbon nanotube N-6- aminohexylamide ,was used as the ionophore.The electrode was manufactured in a concentration range of 1×10-6to1×10-2 , , resulting in a Nernst response with a gradient of 59.1±0.5 mv/decade . In this work, the effects of membrane composition, pH of the solution, temperature and non-aqueous environment were investigated on the performance of the electrodes Furthermore, the response time of the electrode and the electrode response reversibility were calculated using both static and dynamic methods. This electrode can be applied in ethanol environments of up to 25% and in dioxane environments of up to 25% volume-volume without hindrance. The electrode response time was less than 18 seconds.

  14. Electroadsorption Desalination with Carbon Nanotube/PAN-Based Carbon Fiber Felt Composites as Electrodes

    Directory of Open Access Journals (Sweden)

    Yang Liu

    2014-01-01

    Full Text Available The chemical vapor deposition method is used to prepare CNT (carbon nanotube/PCF (PAN-based carbon fiber felt composite electrodes in this paper, with the surface morphology of CNT/PCF composites and electroadsorption desalination performance being studied. Results show such electrode materials with three-dimensional network nanostructures having a larger specific surface area and narrower micropore distribution, with a huge number of reactive groups covering the surface. Compared with PCF electrodes, CNT/PCF can allow for a higher adsorption and desorption rate but lower energy consumption; meanwhile, under the condition of the same voltage change, the CNT/PCF electrodes are provided with a better desalination effect. The study also found that the higher the original concentration of the solution, the greater the adsorption capacity and the lower the adsorption rate. At the same time, the higher the solution’s pH, the better the desalting; the smaller the ions’ radius, the greater the amount of adsorption.

  15. Electroadsorption desalination with carbon nanotube/PAN-based carbon fiber felt composites as electrodes.

    Science.gov (United States)

    Liu, Yang; Zhou, Junbo

    2014-01-01

    The chemical vapor deposition method is used to prepare CNT (carbon nanotube)/PCF (PAN-based carbon fiber felt) composite electrodes in this paper, with the surface morphology of CNT/PCF composites and electroadsorption desalination performance being studied. Results show such electrode materials with three-dimensional network nanostructures having a larger specific surface area and narrower micropore distribution, with a huge number of reactive groups covering the surface. Compared with PCF electrodes, CNT/PCF can allow for a higher adsorption and desorption rate but lower energy consumption; meanwhile, under the condition of the same voltage change, the CNT/PCF electrodes are provided with a better desalination effect. The study also found that the higher the original concentration of the solution, the greater the adsorption capacity and the lower the adsorption rate. At the same time, the higher the solution's pH, the better the desalting; the smaller the ions' radius, the greater the amount of adsorption. PMID:24963504

  16. Chemical attachment of functionalized multiwalled carbon nanotubes on glassy carbon electrode for electrocatalytic application

    International Nuclear Information System (INIS)

    Highlights: • FMWCNTs were covalently attached on GC surface with the aid of alkyldiamine. • The attached FMWCNTs were stable for a wide potential window due to the robust C−N bond. • The composite electrode was prepared by electropolymerizing thiadiazole on FMWCNTs. • The detection limit of 0.27 μM (S/N = 3) of GMP was achieved using composite modified electrode. - Abstract: The covalent attachment of acid functionalized multiwalled carbon nanotubes (FMWCNTs) on glassy carbon (GC) electrode using 1,8-octanediamine (OD) as a linker via carbodiimide chemistry was described. The attachment of FMWCNTs on GC electrode were confirmed by attenuated total reflectance Fourier transform infra-red (ATR-FT-IR) spectroscopy, Raman, scanning electron microscopy (SEM) and electrochemical impedance studies. Raman spectrum of FMWCNTs modified surface shows the characteristic G and D bands at 1563 cm−1 and 1340 cm−1, respectively. This confirmed the successful attachment of FMWCNTs on the OD modified GC surface. Further, the attachment of FMWCNTs on OD modified surface via amide linkage was confirmed from the observed characteristic peak at 1681 cm−1 in the ATR-FT-IR spectrum. The SEM images showed that the covalently attached FMWCNTs retained their morphology similar to powder and the average diameter of them was found to be 58 nm. Unlike modification of FMWCNTs on gold substrates with the aid of conventional thiol linkers (Au−S bond), modification of them by the present method was stable for a wide positive potential window due to the robust C−N bond. To demonstrate the electrochemical stability of the MWCNTs modified electrode at more positive potential, guanosine 5′-monophosphate (GMP) was selected as a representative probe because its oxidation occurs at more than 1 V. It was found that the FMWCNTs modified electrode not only showed a stable signal for GMP but also enhanced its oxidation current when compared to bare GC electrode. Further, the present

  17. Electrochemical Reduction of Oxygen on Anthraquinone/Carbon Nanotubes Nanohybrid Modified Glassy Carbon Electrode in Neutral Medium

    OpenAIRE

    Zheng Gong; Guoquan Zhang; Song Wang

    2013-01-01

    The electrochemical behaviors of monohydroxy-anthraquinone/multiwall carbon nanotubes (MHAQ/MWCNTs) nanohybrid modified glassy carbon (MHAQ/MWCNTs/GC) electrodes in neutral medium were investigated; also reported was their application in the electrocatalysis of oxygen reduction reaction (ORR). The resulting MHAQ/MWCNTs nanohybrid was characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM). It was found that the ORR at the MHAQ/MWCNTs/GC electrode occurs ...

  18. Nanostructured networks of single wall carbon nanotubes for highly transparent, conductive, and anti-reflective flexible electrodes

    OpenAIRE

    Boulanger, Nicolas; Barbero, David

    2013-01-01

    Highly transparent, anti-reflective, flexible, and conductive electrodes are produced by nanopatterning of a polymer composite made of single wall carbon nanotubes (SWNTs). The formation of nanostructures creates interconnected nanotubes and vertically aligned SWNT networks which greatly improves charge transport compared to a traditionally mixed composite. These electrodes moreover possess high transparency (98% at 550 nm) and good anti-reflective properties. The use of low nanotube loadings...

  19. Biosensor based on a glassy carbon electrode modified with tyrosinase immobilized on multiwalled carbon nanotubes

    International Nuclear Information System (INIS)

    We describe a biosensor for phenolic compounds that is based on a glassy carbon electrode modified with tyrosinase immobilized on multiwalled carbon nanotubes (MWNTs). The MWNTs possess excellent inherent electrical conductivity which enhances the electron transfer rate and results in good electrochemical catalytic activity towards the reduction of benzoquinone produced by enzymatic reaction. The biosensor was characterized by cyclic voltammetry, and the experimental conditions were optimized. The cathodic current is linearly related to the concentration of the phenols between 0.4 μM and 10 μM, and the detection limit is 0.2 μM. The method was applied to the determination of phenol in water samples (author)

  20. Electrochemical behaviour of different redox probes on single wall carbon nanotube buckypaper-modified electrodes

    International Nuclear Information System (INIS)

    In the present work, the electrochemical properties of single-walled carbon nanotube buckypapers (BPs) were examined in terms of carbon nanotubes nature and preparation conditions. The performance of the different free-standing single wall carbon nanotube sheets was evaluated via cyclic voltammetry of several redox probes in aqueous electrolyte. Significant differences are observed in the electron transfer kinetics of the buckypaper-modified electrodes for both the outer- and inner-sphere redox systems. These differences can be ascribed to the nature of the carbon nanotubes (nanotube diameter, chirality and aspect ratio), surface oxidation degree and type of functionalities. In the case of dopamine, ferrocene/ferrocenium, and quinone/hydroquinone redox systems the voltammetric response should be thought as a complex contribution of different tips and sidewall domains which act as mediators for the electron transfer between the adsorbate species and the molecules in solution. In the other redox systems only nanotube ends are active sites for the electron transfer. It is also interesting to point out that a higher electroactive surface area not always lead to an improvement in the electron transfer rate of various redox systems. In addition, the current densities produced by the redox reactions studied here are high enough to ensure a proper electrochemical signal, which enables the use of BPs in sensing devices

  1. Fabrication of Functionalized Carbon Nanotube Buckypaper Electrodes for Application in Glucose Biosensors

    Directory of Open Access Journals (Sweden)

    Henry Papa

    2014-11-01

    Full Text Available A highly sensitive glucose detection method was developed using functionalized carbon nanotube buckypaper as a free standing electrode in an electrochemical biosensor. Glucose oxidase was immobilized onto various buckypaper samples in order to oxidize glucose resulting in a measureable current/voltage signal output of the biosensor. Cyclic voltammetry (CV and amperometry were utilized to determine the sensitivity of these buckypaper electrodes. Sensors of three different types of buckypaper were prepared and compared. These modified buckypaper electrode-based sensors showed much higher sensitivity to glucose compared to other electrochemical glucose sensors.

  2. Fabrication of functionalized carbon nanotube buckypaper electrodes for application in glucose biosensors.

    Science.gov (United States)

    Papa, Henry; Gaillard, Melissa; Gonzalez, Leon; Chatterjee, Jhunu

    2014-12-01

    A highly sensitive glucose detection method was developed using functionalized carbon nanotube buckypaper as a free standing electrode in an electrochemical biosensor. Glucose oxidase was immobilized onto various buckypaper samples in order to oxidize glucose resulting in a measureable current/voltage signal output of the biosensor. Cyclic voltammetry (CV) and amperometry were utilized to determine the sensitivity of these buckypaper electrodes. Sensors of three different types of buckypaper were prepared and compared. These modified buckypaper electrode-based sensors showed much higher sensitivity to glucose compared to other electrochemical glucose sensors. PMID:25587433

  3. Fabrication of free-standing carbon nanotube electrode arrays on a quartz wafer

    International Nuclear Information System (INIS)

    For this paper, the fabrication of nano-electrodes by the synthesis of multi-wall carbon nanotubes (MWCNTs) has been investigated. MWCNTs were grown on a TiN coated quartz plate with Fe catalysts patterned by UV nano-imprint lithography (NIL). The proposed study is the realization of a simple, inexpensive and reproducible method to produce nano-scale electrode arrays in large areas. The patterns were defined by an array of circles 200 nm in diameter, and 500 nm in pitch. The nano-patterned master and Fe catalyst are observed with good pattern fidelity over a large area by atomic force microscope (AFM) and scanning electron microscopy (SEM). Among various synthesis methods for carbon nanotube growth, plasma-enhanced chemical-vapor deposition (PECVD) was used for the growth of vertically aligned multi-wall carbon nanotube arrays. Ammonia (NH3) and acetylene (C2H2) were used as the etchant gases and the carbon source, respectively. The carbon nanotubes were vertically aligned in high density on a large area of the plain quartz substrates. High-resolution transmission electron microscopy analysis reveals that the synthesized CNTs are multi-walled with a bamboo-like structure. Patterned catalysts made it possible to allow the precise placement of individual CNT electrodes on the substrate. These electrodes have diameters ranging from 50 nm to 100 nm and lengths of about 300 nm. A field emission test using isolated CNTs on quartz plates showed the ability of CNTs as nano-electrodes. Bio-compatibility was also investigated by cell culturing on the fabricated CNTs/quartz template for potential bio-applications.

  4. Single-walled carbon nanotubes modified carbon ionic liquid electrode for sensitive electrochemical detection of rutin

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Zhihong [Institute of Nano-Science and Technology Center, Huazhong Normal University, Wuhan 430079 (China); Sun Xiaoying; Zhuang Xiaoming [College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Zeng Yan [Institute of Nano-Science and Technology Center, Huazhong Normal University, Wuhan 430079 (China); Sun Wei, E-mail: sunwei@qust.edu.c [College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Huang Xintang [Institute of Nano-Science and Technology Center, Huazhong Normal University, Wuhan 430079 (China)

    2010-11-01

    The single-walled carbon nanotubes (SWCNTs) modified carbon ionic liquid electrode (CILE) was designed and further used for the voltammetric detection of rutin in this paper. CILE was prepared by mixing graphite powder with ionic liquid (IL) 1-butyl-3-methylimidazolium tetrafluoroborate and liquid paraffin together. Based on the interaction of SWCNTs with IL present on the electrode surface, a stable SWCNTs film was formed on the CILE to get a modified electrode denoted as SWCNTs/CILE. The characteristics of SWCNTs/CILE were recorded by different methods including cyclic voltammetry, electrochemical impedance spectroscopy and scanning electron microscopy. The electrochemical behaviors of rutin on the SWCNTs/CILE were investigated by cyclic voltammetry and differential pulse voltammetry. Due to the specific interface provided by the SWCNTs-IL film, the electrochemical response of rutin was greatly enhanced with a pair of well-defined redox peaks appeared in pH 2.5 phosphate buffer solution. The oxidation peak currents showed good linear relationship with the rutin concentration in the range from 1.0 x 10{sup -7} to 8.0 x 10{sup -4} mol/L with the detection limit as 7.0 x 10{sup -8} mol/L (3{sigma}). The SWCNTs/CILE showed the advantages such as excellent selectivity, improved performance, good stability and it was further applied to the rutin tablets sample detection with satisfactory results.

  5. Electrochemical impedance-based DNA sensor using a modified single walled carbon nanotube electrode

    International Nuclear Information System (INIS)

    Carbon nanotubes have become promising functional materials for the development of advanced electrochemical biosensors with novel features which could promote electron-transfer with various redox active biomolecules. This paper presents the detection of Salmonella enterica serovar Typhimurium using chemically modified single walled carbon nanotubes (SWNTs) with single stranded DNA (ssDNA) on a polished glassy carbon electrode. Hybridization with the corresponding complementary ssDNA has shown a shift in the impedance studies due to a higher charge transfer in ssDNA. The developed biosensor has revealed an excellent specificity for the appropriate targeted DNA strand. The methodologies to prepare and functionalize the electrode could be adopted in the development of DNA hybridization biosensor.

  6. Electrochemical impedance-based DNA sensor using a modified single walled carbon nanotube electrode

    Energy Technology Data Exchange (ETDEWEB)

    Weber, Jessica E. [Department of Mechanical Engineering, University of South Florida, Tampa, FL (United States); Nanomaterials and Nanomanufacturing Research Center, University of South Florida, Tampa, FL (United States); Pillai, Shreekumar [Center for NanoBiotechnology Research, Alabama State University, Montgomery, AL (United States); Ram, Manoj Kumar, E-mail: mkram@usf.edu [Department of Mechanical Engineering, University of South Florida, Tampa, FL (United States); Nanomaterials and Nanomanufacturing Research Center, University of South Florida, Tampa, FL (United States); Kumar, Ashok [Department of Mechanical Engineering, University of South Florida, Tampa, FL (United States); Nanomaterials and Nanomanufacturing Research Center, University of South Florida, Tampa, FL (United States); Singh, Shree R. [Center for NanoBiotechnology Research, Alabama State University, Montgomery, AL (United States)

    2011-07-20

    Carbon nanotubes have become promising functional materials for the development of advanced electrochemical biosensors with novel features which could promote electron-transfer with various redox active biomolecules. This paper presents the detection of Salmonella enterica serovar Typhimurium using chemically modified single walled carbon nanotubes (SWNTs) with single stranded DNA (ssDNA) on a polished glassy carbon electrode. Hybridization with the corresponding complementary ssDNA has shown a shift in the impedance studies due to a higher charge transfer in ssDNA. The developed biosensor has revealed an excellent specificity for the appropriate targeted DNA strand. The methodologies to prepare and functionalize the electrode could be adopted in the development of DNA hybridization biosensor.

  7. Layered carbon nanotube-polyelectrolyte electrodes outperform traditional neural interface materials.

    Science.gov (United States)

    Jan, Edward; Hendricks, Jeffrey L; Husaini, Vincent; Richardson-Burns, Sarah M; Sereno, Andrew; Martin, David C; Kotov, Nicholas A

    2009-12-01

    The safety, function, and longevity of implantable neuroprosthetic and cardiostimulating electrodes depend heavily on the electrical properties of the electrode-tissue interface, which in many cases requires substantial improvement. While different variations of carbon nanotube materials have been shown to be suitable for neural excitation, it is critical to evaluate them versus other materials used for bioelectrical interfacing, which have not been done in any study performed so far despite strong interest to this area. In this study, we carried out this evaluation and found that composite multiwalled carbon nanotube-polyelectrolyte (MWNT-PE) multilayer electrodes substantially outperform in one way or the other state-of-the-art neural interface materials available today, namely activated electrochemically deposited iridium oxide (IrOx) and poly(3,4-ethylenedioxythiophene) (PEDOT). Our findings provide the concrete experimental proof to the much discussed possibility that carbon nanotube composites can serve as excellent new material for neural interfacing with a strong possibility to lead to a new generation of implantable electrodes. PMID:19785391

  8. Preparation and electrochemical performance of polyaniline-based carbon nanotubes as electrode material for supercapacitor

    International Nuclear Information System (INIS)

    Nitrogen-containing carbon nanotubes (CNTs) with open end and low specific surface area were prepared via the carbonization of polyaniline (PANI) nanotubes synthesized by a rapidly mixed reaction. On the basis of analyzing the morphologies and structures of the original and carbonized PANI nanotubes, the electrochemical properties of PANI-based CNTs obtained at different temperatures as electrode materials for supercapacitors using 30 wt.% aqueous solution of KOH as electrolyte were investigated by galvanostatic charge/discharge and cyclic voltammetry. It was found that the carbonized PANI nanotubes at 700 oC exhibit high specific capacitance of 163 F g-1 at a current density of 0.1 A g-1 and excellent rate capability in KOH solution. Using X-ray photoelectron spectroscopy measurement the nitrogen state and content in PANI-CNTs were analysed, which could play important roles for the enhancement of electrochemical performance. When the appropriate content of nitrogen is present, the presence of pyrrole or pyridone and quaternary nitrogen is beneficial for the improvement of electron mobility and the wettability of electrode.

  9. Electrocatalytic response of poly(cobalt tetraaminophthalocyanine)/multi-walled carbon nanotubes-Nafion modified electrode toward sulfadiazine in urine*

    OpenAIRE

    Hong, Xiao-ping; Zhu, Yan; Zhang, Yan-zhen

    2012-01-01

    A highly sensitive amperometric sulfadiazine sensor fabricated by electrochemical deposition of poly(cobalt tetraaminophthalocyanine) (poly(CoIITAPc)) on the surface of a multi-walled carbon nanotubes-Nafion (MWCNTs-Nafion) modified electrode is described. This electrode showed a very attractive performance by combining the advantages of CoIITAPc, MWCNTs, and Nafion. Compared with the bare glassy carbon electrode (GCE) and the MWCNTs-Nafion modified electrode, the electrocatalytic activity of...

  10. Fabrication of functional micro- and nanoneedle electrodes using a carbon nanotube template and electrodeposition

    Directory of Open Access Journals (Sweden)

    Lee Eunjoo

    2011-01-01

    Full Text Available Abstract Carbon nanotube (CNT is an attractive material for needle-like conducting electrodes because it has high electrical conductivity and mechanical strength. However, CNTs cannot provide the desired properties in certain applications. To obtain micro- and nanoneedles having the desired properties, it is necessary to fabricate functional needles using various other materials. In this study, functional micro- and nanoneedle electrodes were fabricated using a tungsten tip and an atomic force microscope probe with a CNT needle template and electrodeposition. To prepare the conductive needle templates, a single-wall nanotube nanoneedle was attached onto the conductive tip using dielectrophoresis and surface tension. Through electrodeposition, Au, Ni, and polypyrrole were each coated successfully onto CNT nanoneedle electrodes to obtain the desired properties.

  11. Hydrogen peroxide biosensor based on electrodeposition of zinc oxide nanoflowers onto carbon nanotubes film electrode

    Institute of Scientific and Technical Information of China (English)

    Hui Ping Bai; Xu Xiao Lu; Guang Ming Yang; Yun Hui Yang

    2008-01-01

    A new amperometric biosensor for hydrogen peroxide was developed based on adsorption of horseradish peroxidase at the glassy carbon electrode modified with zinc oxide nanoflowers produced by electrodeposition onto multi-walled carbon nanotubes (MWNTs) firm. The morphology of the MWNTs/nano-ZnO electrode has been investigated by scanning electron microscopy (SEM), and the electrochemical performance of the electrode has also been studied by amperometric method. The resulting electrode offered an excellent detection for hydrogen peroxide at -0.11 V with a linear response range of 9.9 × 10(-7) to 2.9 × 10(-3) mol/L with a correlation coefficient of 0.991, and response time <5 s. The biosensor displays rapid response and expanded linear response range, and excellent stability.

  12. Fabrication and electrochemical properties of free-standing single-walled carbon nanotube film electrodes

    Institute of Scientific and Technical Information of China (English)

    Niu Zhi-Qiang; Ma Wen-Jun; Dong Hai-Bo; Li Jin-Zhu; Zhou Wei-Ya

    2011-01-01

    An easily manipulative approach was presented to fabricate electrodes using free-standing single-walled carbon nanotube (SWCNT) films grown directly by chemical vapor deposition. Electrochemical properties of the electrodes were investigated. In comparison with the post-deposited SWCNT papers, the directly grown SWCNT film electrodes manifested enhanced electrochemical properties and sensitivity of sensors as well as excellent electrocatalytic activities. A transition from macroelectrode to nanoelectrode behaviours was observed with the increase of scan rate. The heat treatment of the SWCNT film electrodes increased the current signals of electrochemical analyser and background current, because the heat-treatment of the SWCNTs in air could create more oxide defects on the walls of the SWCNTs and make the surfaces of SWCNTs more hydrophilic. The excellent electrochemical properties of the directly grown and heat-treated free-standing SWCNT film electrodes show the potentials in biological and electrocatalytic applications.

  13. Titanyl phthalocyanine ambipolar thin film transistors making use of carbon nanotube electrodes

    International Nuclear Information System (INIS)

    The capability of efficiently injecting charge carriers into organic films and finely tuning their morphology and structure is crucial to improve the performance of organic thin film transistors (OTFTs). In this work, we investigate OTFTs employing carbon nanotubes (CNTs) as the source-drain electrodes and, as the organic semiconductor, thin films of titanyl phthalocyanine (TiOPc) grown by supersonic molecular beam deposition (SuMBD). While CNT electrodes have shown an unprecedented ability to improve charge injection in OTFTs, SuMBD is an effective technique to tune film morphology and structure. Varying the substrate temperature during deposition, we were able to grow both amorphous (low substrate temperature) and polycrystalline (high substrate temperature) films of TiOPc. Regardless of the film morphology and structure, CNT electrodes led to superior charge injection and transport performance with respect to benchmark Au electrodes. Vacuum annealing of polycrystalline TiOPc films with CNT electrodes yielded ambipolar OTFTs. (paper)

  14. The determination of acetaminophen using a carbon nanotube:graphite-based electrode

    International Nuclear Information System (INIS)

    The oxidation of acetaminophen was studied at a glassy carbon electrode modified with multi-walled carbon nanotubes and a graphite paste. Cyclic voltamety, differential pulse voltammetry and square wave voltammetry at various pH values, scan rates, and the effect of the ratio of nanotubes to graphite were investigated in order to optimize the parameters for the determination of acetaminophen. Square wave voltammetry is the most appropriate technique in giving a characteristic peak at 0. 52 V at pH 5. The porous nanostructure of the electrode improves the surface area which results in an increase in the peak current. The voltammetric response is linear in the range between 75 and 2000 ng. mL-1, with standard deviations between 0. 25 and 7. 8%, and a limit of detection of 25 ng. mL-1. The method has been successfully applied to the analysis of acetaminophen in tablets and biological fluids. (author)

  15. Manganese Detection with a Metal Catalyst Free Carbon Nanotube Electrode: Anodic versus Cathodic Stripping Voltammetry

    OpenAIRE

    Yue, Wei; Bange, Adam; Riehl, Bill L.; Riehl, Bonnie D.; Johnson, Jay M.; Papautsky, Ian; Heineman, William R.

    2012-01-01

    Anodic stripping voltammetry (ASV) and cathodic stripping voltammetry (CSV) were used to determine Mn concentration using metal catalyst free carbon nanotube (MCFCNT) electrodes and square wave stripping voltammetry (SWSV). The MCFCNTs are synthesized using a Carbo Thermal Carbide Conversion method which results in a material that does not contain residual transition metals. Detection limits of 120 nM and 93 nM were achieved for ASV and CSV, respectively, with a deposition time of 60 s. CSV w...

  16. Electronic transport properties of a molecular switch with carbon nanotube electrodes: A first-principles study

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, P., E-mail: ss_zhaop@ujn.edu.c [School of Science, University of Jinan, Jinan 250022 (China); School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Wang, P.J.; Zhang, Z. [School of Science, University of Jinan, Jinan 250022 (China); Liu, D.S. [School of Physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Department of Physics, Jining University, Qufu 273155 (China)

    2010-01-01

    We have studied the electronic transport properties of a new kind of optical molecular switch with two single-walled carbon nanotube (SWCNT) electrodes using first-principles transport calculations. It is shown that the enol form shows an overall higher conductance than the keto form at low-bias voltage, which is independent of the SWCNTs' chirality. Meantime, it is possible to tune the conductance of the molecular switch by changing the chirality of the SWCNTs.

  17. Performance of a combined capacitor based on ultrafine nickel oxide/carbon nanotubes composite electrodes

    Institute of Scientific and Technical Information of China (English)

    Xiaofeng Wang; Yanqiu Cao; Yiqiang Lu; Qiqian Sha; Ji Liang

    2004-01-01

    A new sol-gel process for the preparation of ultrafine nickel hydroxide electrode materials was developed. The composite electrodes consisting of carbon nanotubes and Ni(OH)2 were developed by mixing the hydroxide and carbon nanotubes together in different mass ratios. In order to enhance energy density, a combined type pseudocapacitor/electric double layer capacitor was considered and its electrochemical properties were characterized by cyclic voltammetry and dc charge/discharge test. The combined capacitor shows excellent capacitor behavior with an operating voltage up to 1.6 V in KOH aqueous electrolyte. Stable charge/discharge behaviors were observed with much higher specific capacitance values of 24 F/g compared with that of EDLC (12F/g) by introducing 60% Ni(OH)2 in the anode material. By using the modified anode of a Ni(OH)2/carbon nanotubes composite electrode, the specific capacitance of the cell was less sensitive to discharge current density compared with that of the capacitor employing pure nickel hydroxide as anode. The combined capacitor in this study exhibits high energy density and stable power characteristics.

  18. Voltammetric determination of theophylline at a Nafion/multi-wall carbon nanotubes composite film-modified glassy carbon electrode

    Indian Academy of Sciences (India)

    Suling Yang; Ran Yang; Gang Li; Jianjun Li; Lingbo Qu

    2010-11-01

    A Nafion/multi-wall carbon nanotubes (MWNTs) composite film-modified electrode was fabricated and applied to the sensitive and convenient determination of theophylline (TP). Multi-wall carbon nanotubes (MWNTs) were easily dispersed homogeneously into 0.1% Nafion methanol solution by sonication. Appropriate amount of Nafion/MWNTs suspension was coated on a glassy carbon electrode. After evaporating methanol, a Nafion/MWNTs composite film-modified electrode was achieved. TP could effectively accumulate at Nafion/MWNTs composite film-modified electrode and cause a sensitive anodic peak at around 1180 mV (vs SCE) in 0.01 mol/L H2SO4 medium (pH 1.8). In contrast with the bare glassy carbon electrode, Nafion film-modified electrode, Nafion/MWNTs film-modified electrode could remarkably increase the anodic peak current and decreased the overpotential of TP oxidation. Under the optimized conditions, the anodic peak current was proportional to TP concentration in the range of 8.0 × 10-8-6.0 × 10-5 mol/L, with a detection limit of 2.0 × 10-8 mol/L. This newly developed method was used to determine TP in drug samples with good percentage of recoveries.

  19. Inkjet printed multiwall carbon nanotube electrodes for dielectric elastomer actuators

    Science.gov (United States)

    Baechler, Curdin; Gardin, Samuele; Abuhimd, Hatem; Kovacs, Gabor

    2016-05-01

    Dielectric elastomers (DE’s) offer promising applications as soft and light-weight electromechanical actuators. It is known that beside the dielectric material, the electrode properties are of particular importance regarding the DE performance. Therefore, in recent years various studies have focused on the optimization of the electrode in terms of conductivity, stretchability and reliability. However, less attention was given to efficient electrode processing and deposition methods. In the present study, digital inkjet printing was used to deposit highly conductive and stretchable electrodes on silicone. Inkjet printing is a versatile and cost effective deposition method, which allows depositing complex-shaped electrode patterns with high precision. The electrodes were printed using an ink based on industrial low-cost MWCNT. Experiments have shown that the strain-conductivity properties of the printed electrode are strongly depended on the deposition parameters like drop-spacing and substrate temperature. After the optimization of the printing parameters, thin film electrodes could be deposited showing conductivities of up to 30 S cm-1 without the need of any post-treatment. In addition, electromechanical tests with fabricated DE actuators have revealed that the inkjet printed MWCNT electrodes are capable to self-clear in case of a dielectric breakdown.

  20. Electrocatalytic oxidation of deferiprone and its determination on a carbon nanotube-modified glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Yadegari, H. [Department of Chemistry, Faculty of Science, K.N. Toosi University of Technology, P.O. Box 16315-1618, Tehran (Iran, Islamic Republic of); Jabbari, A. [Department of Chemistry, Faculty of Science, K.N. Toosi University of Technology, P.O. Box 16315-1618, Tehran (Iran, Islamic Republic of)], E-mail: jabbari@kntu.ac.ir; Heli, H.; Moosavi-Movahedi, A.A. [Institute of Biochemistry and Biophysics, University of Tehran, Tehran (Iran, Islamic Republic of); Karimian, K. [Arasto Pharmaceutical Chemicals Inc., Tehran (Iran, Islamic Republic of); Khodadadi, A. [Department of Chemical Engineering, Faculty of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

    2008-02-15

    The electrochemical behavior of the anti-thalassemia and anti-HIV replication drug, deferiprone, was investigated on a carbon nanotube-modified glassy carbon (GC-CNT) electrode in phosphate buffer solution, pH 7.40 (PBS). During oxidation of deferiprone, two irreversible anodic peaks, with E{sub 1}{sup 0}=452 and E{sub 2}{sup 0}=906mV, appeared, using GC-CNT. Cyclic voltammetric study indicated that the oxidation process is irreversible and diffusion controlled. The number of exchanged electrons in the electro-oxidation process was obtained, and the data indicated that deferiprone is oxidized via two two-electron steps. The results revealed that carbon nanotube (CNT) promotes the rate of oxidation by increasing the peak current, so that deferiprone is oxidized at lower potentials, which thermodynamically is more favorable. This result was confirmed by impedance measurements. The diffusion coefficient, electron-transfer coefficient and heterogeneous electron-transfer rate constant of deferiprone were found to be 1.49 x 10{sup -6} cm{sup 2} s{sup -1}, 0.44, and 3.83 x 10{sup -3} cm s{sup -1}, respectively. A sensitive, simple and time-saving differential-pulse voltammetric procedure was developed for the analysis of deferiprone. Using the proposed method, deferiprone can be determined with a detection limit of 5.25 x 10{sup -7} M. The applicability of the method to direct assays of spiked human serum and urine fluids is described.

  1. Pseudocapacitive Effects of N-Doped Carbon Nanotube Electrodes in Supercapacitors

    Directory of Open Access Journals (Sweden)

    Hyun Ho Park

    2012-07-01

    Full Text Available Nitrogen- and micropore-containing carbon nanotubes (NMCNTs were prepared by carbonization of nitrogen-enriched, polymer-coated carbon nanotubes (CNTs, and the electrochemical performances of the NMCNTs with different heteroatom contents were investigated. NMCNTs-700 containing 9.1 wt% nitrogen atoms had a capacitance of 190.8 F/g, which was much higher than that of pristine CNTs (48.4 F/g, despite the similar surface area of the two CNTs, and was also higher than that of activated CNTs (151.7 F/g with a surface area of 778 m2/g and a nitrogen atom content of 1.2 wt%. These results showed that pseudocapacitive effects play an important role in the electrochemical performance of supercapacitor electrodes.

  2. Gold nanoparticle decorated multi-walled carbon nanotubes as counter electrode for dye sensitized solar cells.

    Science.gov (United States)

    Kaniyoor, Adarsh; Ramaprabhu, Sundara

    2012-11-01

    A novel counter electrode material for dye sensitized solar cells (DSSCs) composed of nanostructured Au particles decorated on functionalized multi-walled carbon nanotubes (f-MWNTs) is demonstrated for the first time. MWNTs synthesized by catalytic chemical vapor deposition technique are purified and functionalized by treating with concentrated acids. Au nanoparticles are decorated on f-MWNTs by a rapid and facile microwave assisted polyol reduction method. The materials are characterized by X-ray diffractometry, Fourier transform infra red spectroscopy and electron microscopy. The DSSC fabricated with Au/f-MWNTs based counter electrode shows enhanced power conversion efficiency (eta) of 4.9% under AM 1.5G simulated solar radiation. In comparison, the reference DSSCs fabricated with f-MWNTs and Pt counter electrodes show eta of 2.1% and 4.5%. This high performance of Au/f-MWNTs counter electrode is investigated using electrochemical impedance spectroscopy and cyclic voltammetry studies. PMID:23421212

  3. Flexible supercapacitor electrodes with vertically aligned carbon nanotubes grown on aluminum foils

    Institute of Scientific and Technical Information of China (English)

    Itir Bakis Dogru; Mete Batuhan Durukan; Onur Turel; Husnu Emrah Unalan

    2016-01-01

    In this work, vertically aligned carbon nanotubes (VACNTs) grown on aluminum foils were used as flexible supercapacitor electrodes. Aluminum foils were used as readily available, cheap and conductive substrates, and VACNTs were grown directly on these foils through chemical vapor deposition (CVD) method. Solution based ultrasonic spray pyrolysis (USP) method was used for the deposition of the CNT catalyst. Direct growth of VACNTs on aluminum foils ruled out both the internal resistance of the su-percapacitor electrodes and the charge transfer resistance between the electrode and electrolyte. A specific capacitance of 2.61 mF/cm2 at a scan rate of 800 mV/s was obtained from the fabricated elec-trodes, which is further improved through the bending cycles.

  4. Theoretical Simulation on the Assembly of Carbon Nanotubes Between Electrodes by AC Dielectrophoresis

    Directory of Open Access Journals (Sweden)

    Yang Liu

    2008-01-01

    Full Text Available Abstract The assembly of single-walled carbon nanotubes (SWCNTs using the AC dielectrophoresis technique is studied theoretically. It is found that the comb electrode bears better position control of SWCNTs compared to the parallel electrode. In the assembly, when some SWCNTs bridge the electrode first, they can greatly alter the local electrical field so as to “screen off” later coming SWCNTs, which contributes to the formation of dispersed SWCNT array. The screening distance scales with the gap width of electrodes and the length of SWCNTs, which provides a way to estimate the assembled density of SWCNTs. The influence of thermal noise on SWCNTs alignment is also analyzed in the simulation. It is shown that the status of the array distribution for SWCNTs is decided by the competition between the thermal noise and the AC electric-field strength. This influence of the thermal noise can be suppressed by using higher AC voltage to assemble the SWCNTs.

  5. Portable cholesterol detection with polyaniline-carbon nanotube film based interdigitated electrodes

    International Nuclear Information System (INIS)

    Polyaniline-carboxylic multiwalled carbon nanotubes composite film (PANi-MWCNT) has been polymerized on the surface of interdigitated platinum electrode (fabricated by MEMS technology) which was compatibly connected to Autolab interface via universal serial bus (USB). An amperometric biosensor based on covalent immobilization of cholesterol oxidase (ChOx) on PANi–MWCNT film with potassium ferricyanide (FeCN) as the redox mediator was developed. The mediator helps to shuttle the electrons between the immobilized ChOx and the PANi-MWCNT electrode, therefore operating at a low potential of −0.3 V compared to the saturated calomel electrode (SCE). This potential precludes the interfering compounds from oxidization. The bio-electrode exhibits good linearity from 0.02 to 1.2 mM cholesterol concentration with a correlation coefficient of 0.9985

  6. Flexible supercapacitor electrodes with vertically aligned carbon nanotubes grown on aluminum foils

    Directory of Open Access Journals (Sweden)

    Itir Bakis Dogru

    2016-06-01

    Full Text Available In this work, vertically aligned carbon nanotubes (VACNTs grown on aluminum foils were used as flexible supercapacitor electrodes. Aluminum foils were used as readily available, cheap and conductive substrates, and VACNTs were grown directly on these foils through chemical vapor deposition (CVD method. Solution based ultrasonic spray pyrolysis (USP method was used for the deposition of the CNT catalyst. Direct growth of VACNTs on aluminum foils ruled out both the internal resistance of the supercapacitor electrodes and the charge transfer resistance between the electrode and electrolyte. A specific capacitance of 2.61 mF/cm2 at a scan rate of 800 mV/s was obtained from the fabricated electrodes, which is further improved through the bending cycles.

  7. Roll to plate printed stretchable silver electrode using single walled carbon nanotube on elastomeric substrate.

    Science.gov (United States)

    Jung, Minhun; Noh, Jinsoo; Kim, Junseok; Kim, Donghwan; Cho, Gyoujin

    2013-08-01

    Stretchable electronics may open new applications in display, sensors and actuators. To attain the stretchable electronics, the ink formulation should be compatible with elastomeric substrates. Here, we present the formulation of silver nanoparticles and single walled carbon nanotubes (SWNTs) for printing stretchable silver electrodes on the elastomeric substrates. Highly conductive stretchable electrodes can be printed directly on the poly(styrene-b-butadiene-b-styrene) (PSBS) substrates by roll to plate (R2P) gravure printer. During the stretching test, R2P printed silver based stretchable electrodes show the high conductivity of 1000 S cm(-1) at 0.27 wt% of SWNT loading. Furthermore, the resistance of the printed silver electrode was not changed up to 15% of tensile strain. PMID:23882805

  8. Electrocatalytic detection of insulin at RuOx/carbon nanotube-modified carbon electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Joseph [Departments of Chemical and Material Engineering, Chemistry and Biochemistry, The Biodesign Institute, Arizona State University, Tempe, AZ 85287-5801 (United States)]. E-mail: joseph.wang@asu.edu; Tangkuaram, Tanin [Departments of Chemical and Material Engineering, Chemistry and Biochemistry, The Biodesign Institute, Arizona State University, Tempe, AZ 85287-5801 (United States); Department of Chemistry, Mahidol University, Bangkok 10400 (Thailand); Loyprasert, Suchera [Departments of Chemical and Material Engineering, Chemistry and Biochemistry, The Biodesign Institute, Arizona State University, Tempe, AZ 85287-5801 (United States); Department of Chemistry, Prince of Songkla University, Songkhla 90000 (Thailand); Vazquez-Alvarez, Terannie [Departments of Chemical and Material Engineering, Chemistry and Biochemistry, The Biodesign Institute, Arizona State University, Tempe, AZ 85287-5801 (United States); Veerasai, Waret [Department of Chemistry, Mahidol University, Bangkok 10400 (Thailand); Kanatharana, Proespichaya [Department of Chemistry, Prince of Songkla University, Songkhla 90000 (Thailand); Thavarungkul, Panote [Department of Chemistry, Prince of Songkla University, Songkhla 90000 (Thailand)

    2007-01-02

    A bilayer surface coating, prepared by electrodepositing ruthenium oxide (RuOx) onto a carbon nanotube (CNT) layer, offers dramatic improvements in the stability and sensitivity of voltammetric and amperometric measurements of insulin compared to the individual (CNT or RuOx) coated electrodes. The enhanced electrocatalytic activity towards insulin is indicated from lowering the potential of the oxidation process (starting around 0.35 versus Ag/AgCl) and the substantially higher sensitivity over the entire potential range. A wide linear dynamic range (10-800 nM) was achieved with a detection limit of 1 nM. The marked electrocatalytic activity of the RuOx/CNT coating towards insulin is coupled with a greatly enhanced stability. For example, the insulin amperometric response of the RuOx/CNT-coated electrodes is highly stable, with 97% of the initial activity remaining after 60 min stirring of 2 x 10{sup -6} M solution (compared to significantly faster current diminutions at the RuOx- or CNT-coated surfaces). The results suggest great promise for miniaturized sensors and detectors for monitoring insulin.

  9. Electrocatalytic detection of insulin at RuOx/carbon nanotube-modified carbon electrodes

    International Nuclear Information System (INIS)

    A bilayer surface coating, prepared by electrodepositing ruthenium oxide (RuOx) onto a carbon nanotube (CNT) layer, offers dramatic improvements in the stability and sensitivity of voltammetric and amperometric measurements of insulin compared to the individual (CNT or RuOx) coated electrodes. The enhanced electrocatalytic activity towards insulin is indicated from lowering the potential of the oxidation process (starting around 0.35 versus Ag/AgCl) and the substantially higher sensitivity over the entire potential range. A wide linear dynamic range (10-800 nM) was achieved with a detection limit of 1 nM. The marked electrocatalytic activity of the RuOx/CNT coating towards insulin is coupled with a greatly enhanced stability. For example, the insulin amperometric response of the RuOx/CNT-coated electrodes is highly stable, with 97% of the initial activity remaining after 60 min stirring of 2 x 10-6 M solution (compared to significantly faster current diminutions at the RuOx- or CNT-coated surfaces). The results suggest great promise for miniaturized sensors and detectors for monitoring insulin

  10. Electrochemical Reduction of Oxygen on Anthraquinone/Carbon Nanotubes Nanohybrid Modified Glassy Carbon Electrode in Neutral Medium

    Directory of Open Access Journals (Sweden)

    Zheng Gong

    2013-01-01

    Full Text Available The electrochemical behaviors of monohydroxy-anthraquinone/multiwall carbon nanotubes (MHAQ/MWCNTs nanohybrid modified glassy carbon (MHAQ/MWCNTs/GC electrodes in neutral medium were investigated; also reported was their application in the electrocatalysis of oxygen reduction reaction (ORR. The resulting MHAQ/MWCNTs nanohybrid was characterized by scanning electron microscope (SEM and transmission electron microscope (TEM. It was found that the ORR at the MHAQ/MWCNTs/GC electrode occurs irreversibly at a potential about 214 mV less negative than at a bare GC electrode in pH 7.0 buffer solution. Cyclic voltammetric and rotating disk electrode (RDE techniques indicated that the MHAQ/MWCNTs nanohybrid has high electrocatalytic activity for the two-electron reduction of oxygen in the studied potential range. The kinetic parameters of ORR at the MHAQ/MWCNTs nanohybrid modified GC electrode were also determined by RDE and EIS techniques.

  11. Functionalization of carbon nanotube and nanofiber electrodes with biological macromolecules: Progress toward a nanoscale biosensor

    Science.gov (United States)

    Baker, Sarah E.

    The integration of nanoscale carbon-based electrodes with biological recognition and electrical detection promises unparalleled biological detection systems. First, biologically modified carbon-based materials have been shown to have superior long-term chemical stability when compared to other commonly used materials for biological detection such as silicon, gold, and glass surfaces. Functionalizing carbon electrodes for biological recognition and using electrochemical methods to transduce biological binding information will enable real-time, hand-held, lower cost and stable biosensing devices. Nanoscale carbon-based electrodes allow the additional capability of fabricating devices with high densities of sensing elements, enabling multi-analyte detection on a single chip. We have worked toward the integration of these sensor components by first focusing on developing and characterizing the chemistry required to functionalize single-walled carbon nanotubes and vertically aligned carbon nanofibers with oligonucleotides and proteins for specific biological recognition. Chemical, photochemical and electrochemical methods for functionalizing these materials with biological molecules were developed. We determined, using fluorescence and colorimetric techniques, that these biologically modified nanoscale carbon electrodes are biologically active, selective, and stable. A photochemical functionalization method enabled facile functionalization of dense arrays vertically aligned carbon nanofiber forests. We found that much of the vertically aligned carbon nanofiber sidewalls were functionalized and biologically accessible by this method---the absolute number of DNA molecules hybridized to DNA-functionalized nanofiber electrodes was ˜8 times higher than the number of DNA molecules hybridized to flat glassy carbon electrodes and implies that nanofiber forest sensors may facilitate higher sensitivity to target DNA sequences per unit area. We also used the photochemical method

  12. Control of geometrical properties of carbon nanotube electrodes towards high-performance microbial fuel cells

    Science.gov (United States)

    Erbay, Celal; Pu, Xiong; Choi, Woongchul; Choi, Mi-Jin; Ryu, Yeontack; Hou, Huijie; Lin, Furong; de Figueiredo, Paul; Yu, Choongho; Han, Arum

    2015-04-01

    In microbial fuel cells (MFCs), physical and electrochemical interactions between microbes and electrode surfaces are critical to performance. Nanomaterial-based electrodes have shown promising performances, however their unique characteristics have not been fully utilized. The developed electrodes here consist of multi-wall carbon nanotubes (MWCNTs) directly grown in the radial direction from the wires of stainless steel (SS) meshes, providing extremely large three-dimensional surfaces while ensuring minimal ohmic loss between CNTs and SS meshes, fully utilizing the advantages of CNTs. Systematic studies on how different lengths, packing densities, and surface conditions of CNTs affect MFC power output revealed that long and loosely packed CNTs without any amorphous carbon show the highest power production performance. The power density of this anode is 7.4-fold higher compared to bare carbon cloth, which is the highest reported improvement for MFCs with nanomaterial-decorated electrodes. The results of this study offer great potential for advancing the development of microbial electrochemical systems by providing a highly efficient nanomaterial-based electrode that delivers large surface area, high electrochemical activity, and minimum ohmic loss, as well as provide design principles for next-generation nanomaterial-based electrodes that can be broadly applicable for highly efficient microbial electrochemical cells.

  13. Performance improvement of pasted nickel electrodes with multi-wall carbon nanotubes for rechargeable nickel batteries

    International Nuclear Information System (INIS)

    Carbon nanotubes (CNTs) were employed as a functional additive to improve the electrochemical performance of pasted nickel-foam electrodes for rechargeable nickel-based batteries. The nickel electrodes were prepared with spherical β-Ni(OH)2 powder as the active material and various amounts of CNTs as additives. Galvanostatic charge/discharge cycling tests showed that in comparison with the electrode without CNTs, the pasted nickel electrode with added CNTs exhibited better electrochemical properties in the chargeability, specific discharge capacity, active material utilization, discharge voltage, high-rate capability and cycling stability. Meanwhile, the CNT addition also lowered the packing density of Ni(OH)2 particles in the three-dimensional porous nickel-foam substrate, which could lead to the decrease in the active material loading and discharge capacity of the electrode. Hence, the amount of CNTs added to Ni(OH)2 should be optimized to obtain a high-performance nickel electrode, and an optimum amount of CNT addition was found to be 3 wt.%. The superior electrochemical performance of the nickel electrode with CNTs could be attributed to lower electrochemical impedance and less γ-NiOOH formed during charge/discharge cycling, as indicated by electrochemical impedance spectroscopy and X-ray diffraction analyses. Thus, it was an effective method to improve the electrochemical properties of pasted nickel electrodes by adding an appropriate amount of CNTs to spherical Ni(OH)2 as the active material

  14. All-Organic Actuator Fabricated with Single Wall Carbon Nanotube Electrodes

    Science.gov (United States)

    Lowther, Sharon E.; Harrison, Joycelyn S.; Kang, Jinho; Park, Cheol; Park, Chan Eon

    2008-01-01

    Compliant electrodes to replace conventional metal electrodes have been required for many actuators to relieve the constraint on the electroactive layer. Many conducting polymers have been proposed for the alternative electrodes, but they still have a problem of poor thermal stability. This article reports a novel all-organic actuator with single wall carbon nanotube (SWCNT) films as the alternative electrode. The SWCNT film was obtained by filtering a SWCNT solution through an anodized alumina membrane. The conductivity of the SWCNT film was about 280 S/cm. The performance of the SWCNT film electrode was characterized by measuring the dielectric properties of NASA Langley Research Center - Electroactive Polymer (LaRC-EAP) sandwiched by the SWCNT electrodes over a broad range of temperature (from 25 C to 280 C) and frequency (from 1 KHz to 1 MHz). The all-organic actuator with the SWCNT electrodes showed a larger electric field-induced strain than that with metal electrodes, under identical measurement conditions.

  15. Advantages of flattened electrode in bottom contact single-walled carbon nanotube field-effect transistor

    International Nuclear Information System (INIS)

    We fabricated single-walled carbon nanotube (SWNT) field-effect transistor (FET) devices on flattened electrodes, in which there are no height difference between metal electrodes and the substrate. SWNT-FET fabricated using bottom contact technique have some advantages, such that the SWNTs are free from electron irradiation, have direct contact with the desired metal electrodes, and can be functionalized before or after deposition. However, the SWNTs can be bent at the contact point with the metal electrodes leading to a different electrical characteristic of the devices. The number of SWNT direct junctions in short channel length devices is drastically increased by the use of flattened electrodes due to strong attractive interaction between SWNT and the substrate. The flattened electrodes show a better balance between their hole and electron mobility compared to that of the non-flattened electrodes, that is, ambipolar FET characteristic. It is considered that bending of the SWNTs in the non-flattened electrode devices results in a higher Schottky barrier for the electrons.

  16. Characterization of Carbon Nanotube/Graphene on Carbon Cloth as an Electrode for Air-Cathode Microbial Fuel Cells

    Directory of Open Access Journals (Sweden)

    Hung-Yin Tsai

    2015-01-01

    Full Text Available Microbial fuel cells (MFCs, which can generate low-pollution power through microbial decomposition, have become a potentially important technology with applications in environmental protection and energy recovery. The electrode materials used in MFCs are crucial determinants of their capacity to generate electricity. In this study, we investigate the performance of using carbon nanotube (CNT and graphene-modified carbon-cloth electrodes in a single-chamber MFC. We develop a process for fabricating carbon-based modified electrodes and Escherichia coli HB101 in an air-cathode MFC. The results show that the power density of MFCs can be improved by applying a coat of either graphene or CNT to a carbon-cloth electrode, and the graphene-modified electrode exhibits superior performance. In addition, the enhanced performance of anodic modification by CNT or graphene was greater than that of cathodic modification. The internal resistance decreased from 377 kΩ for normal electrodes to 5.6 kΩ for both electrodes modified by graphene with a cathodic catalyst. Using the modified electrodes in air-cathode MFCs can enhance the performance of power generation and reduce the associated costs.

  17. Effect of the rheological properties of carbon nanotube dispersions on the processing and properties of transparent conductive electrodes.

    Science.gov (United States)

    Maillaud, Laurent; Poulin, Philippe; Pasquali, Matteo; Zakri, Cécile

    2015-06-01

    Transparent conductive films are made from aqueous surfactant stabilized dispersions of carbon nanotubes using an up-scalable rod coating method. The processability of the films is governed by the amount of surfactant which is shown to alter strongly the wetting and viscosity of the ink. The increase of viscosity results from surfactant mediated attractive interactions between the carbon nanotubes. Links between the formulation, ink rheological properties, and electro-optical properties of the films are determined. The provided guidelines are generalized and used to fabricate optimized electrodes using conductive polymers and carbon nanotubes. In these electrodes, the carbon nanotubes act as highly efficient viscosifiers that allow the optimized ink to be homogeneously spread using the rod coating method. From a general point of view and in contrast to previous studies, the CNTs are optimally used in the present approach as conductive additives for viscosity enhancements of electronic inks. PMID:25961667

  18. Study on the Highly Sensitive AChE Electrode Based on Multiwalled Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Shuping Zhang

    2014-01-01

    Full Text Available Using chitosan (CS as carrier, the method named layer-by-layer (LBL self-assembly modification to modify the glassy carbon electrode (GCE with multiwalled carbon nanotubes (MWNTs and acetylcholine esterase (AChE was proposed to prepare the acetylcholine esterase electrode with high sensitivity and stability. The modified electrode was used to detect pesticide of aldicarb, and the enzyme inhibition rate of the electrode showed good linearity with pesticide concentrations in the range of 10−10 g·L−1 to 10−3 g·L−1. The detection limit was 10−11 g·L−1. The modified electrode was also used to detect the actual sample, and the recovery rate range was from 97.72% to 107.15%, which could meet the rapid testing need of the aldicarb residue. After being stored in the phosphate buffer solution (PBS in 4°C for 30 days, the modified electrode showed good stability with the response current that was 80% of the original current.

  19. Ionic liquid coated single-walled carbon nanotube buckypaper as supercapacitor electrode

    Institute of Scientific and Technical Information of China (English)

    Chao Zheng; Weizhong Qian; Yuntao Yu; Fei Wei

    2013-01-01

    Effect of stacking structure of single-walled carbon nanotubes (SWCNTs) on its performance as electrode of supercapacitor was investigated in the present work.Considering SWCNTs easily formed bundles due to strong van de Waals attraction between tubes,we proposed first dispersion of SWCNTs by ionic liquids (ILs) of 1-ethyl-3-methyl imidazolium tetrafluoroborate (EMIMBF4),followed by fabrication of buckypaper by compression.The debundling effect of ILs on SWCNTs increased the interface between electrode and electrolyte,decreased electrical resistance,and,consequently,increased performance of the supercapacitor.Since ILs,used to disperse SWCNTs,also functioned as electrolyte in supercapacitor,our method is a simple way to prepare buckypaper electrode with high performance.

  20. Detection of Trace Copper Metal at Carbon Nanotube Based Electrodes Using Squarewave Anodic Stripping Voltammetry

    International Nuclear Information System (INIS)

    We investigate sensitivity and limit of detection (LOD) of trace copper (Cu) metal using pristine carbon nanotube (CNT) and acidified CNT (ACNT) electrodes. Squarewave based anodic stripping voltammetry (SWASV) is used to determine the stripped Cu concentration. Prior to performing the SWASV measurements, its optimal conditions are determined and with that, effects of potential scan rate and Cu2+ concentration on stripping current are evaluated. The measurements indicate that (1) ACNT electrode shows better results than CNT electrode and (2) stripping is controlled by surface reaction. In the given Cu2+ concentration range of 25-150 ppb, peak stripping current has linearity with Cu2+ concentration. Quantitatively, sensitivity and LOD of Cu in ACNT electrode are 9.36 μA μM-1 and 3 ppb, while their values are 3.99 μA μM-1 and 3 ppb with CNT electrode. We evaluate the effect of three different water solutions (deionized water, tap water and river water) on stripping current and the confirm types of water don't affect the sensitivity of Cu. It turns out by optical inspection and cyclic voltammetry that superiority of ACNT electrode to CNT electrode is attributed to exfoliation of CNT bundles and improved interfacial adhesion occurring during oxidation of CNTs

  1. Fabrication and performance evaluation of hybrid supercapacitor electrodes based on carbon nanotubes and sputtered TiO2

    Science.gov (United States)

    Aravinda, L. S.; Nagaraja, K. K.; Nagaraja, H. S.; Udaya Bhat, K.; Ramachandra Bhat, B.

    2016-08-01

    We report a simple and eco-friendly method for the fabrication of a titanium dioxide/functionalized multiwalled carbon nanotube (TiO2/FMWCNT) composite electrode for use in supercapacitors. The nanocomposite electrodes were formed by depositing titanium dioxide onto FMWCNTs using reactive magnetron sputtering, thus providing a green roue for the formation of the binder-free composite electrode. It is shown that the electrochemical performance of the fabricated electrodes can be altered by tuning the thickness of the titanium dioxide overlayer. The integrated nanocomposite electrode showed an improved specific capacitance of 90 Fg‑1 in two-electrode configuration.

  2. Electrochemical detection of carbidopa using a ferrocene-modified carbon nanotube paste electrode

    Directory of Open Access Journals (Sweden)

    FATEMEH KARIMI

    2009-12-01

    Full Text Available A chemically modified carbon paste electrode (MCPE containing ferrocene (FC and carbon nanotubes (CNT was constructed. The electrochemical behavior and stability of the MCPE were investigated by cyclic voltammetry. The electrocatalytic activity of the MCPE was investigated and it showed good characteristics for the oxidation of carbidopa (CD in phosphate buffer solution (PBS. A linear concentration range of 5 to 600 μM CD, with a detection limit of 3.6±0.17 μM CD, was obtained. The diffusion coefficient of CD and the transfer coefficient ( were also determined. The MCPE showed good reproducibility, remarkable long-term stability and especially good surface renewability by simple mechanical polishing. The results showed that this electrode could be used as an electrochemical sensor for the determination of CD in real samples, such as urine samples.

  3. Voltammetric Determination of Ferulic Acid Using Polypyrrole-Multiwalled Carbon Nanotubes Modified Electrode with Sample Application

    Directory of Open Access Journals (Sweden)

    Refat Abdel-Hamid

    2015-10-01

    Full Text Available A polypyrrole-multiwalled carbon nanotubes modified glassy carbon electrode-based sensor was devised for determination of ferulic acid (FA. The fabricated sensor was prepared electrochemically using cyclic voltammetry (CV and characterized using CV and scanning electron microscope (SEM. The electrode shows an excellent electrochemical catalytic activity towards FA oxidation. Under optimal conditions, the anodic peak current correlates linearly to the FA concentration throughout the range of 3.32 × 10−6 to 2.59 × 10−5 M with a detection limit of 1.17 × 10−6 M (S/N = 3. The prepared sensor is highly selective towards ferulic acid without the interference of ascorbic acid. The sensor applicability was tested for total content determination of FA in a commercial popcorn sample and showed a robust functionality.

  4. Square Wave Voltammetric Determination of Residues of Carbendazim Using a Fullerene/Multiwalled Carbon Nanotubes/Nafion/Coated Glassy Carbon Electrode

    OpenAIRE

    Djimadoum N. Teadoum; Seraphine K. Noumbo; Kamdem T. Arnaud; Temgoua T. Ranil; Antoine D. Mvondo Zé; Ignas K. Tonle

    2016-01-01

    A glassy carbon electrode (GCE) was modified with a fullerene/Multiwalled Carbon Nanotubes (MWCNTs)/Nafion composite and applied to the determination of carbendazim, a fungicide. The voltammetric behavior of the analyte was investigated using Cyclic Voltammetry (CV), on the bare GCE and on the same electrode coated by a thin film of the composite material. The electrode response was more than fourfold important on the modified electrode, due to electrical conductivity of fullerene and MWCNT a...

  5. Low temperature growth of carbon nanotubes on printing electrodes by MPCVD

    Energy Technology Data Exchange (ETDEWEB)

    Chen, K.-C. [Department of Materials Science and Engineering, National Chiao Tung University, Taiwan (China) and Electronics Research and Service Organization (ERSO), Industrial Technology Research Institute (ITRI), Hsinchu, Taiwan (China)]. E-mail: northnose@itri.org.tw; Chen, C.-F. [Department of Materials Science and Engineering, National Chiao Tung University, Taiwan (China); Chiang, J.-S. [Union Chemica Laboratories (UCL), Industrial Technology Research Institute (ITRI), Hsinchu, Taiwan, 310 (China); Hwang, C.-L. [Union Chemica Laboratories (UCL), Industrial Technology Research Institute (ITRI), Hsinchu, Taiwan, 310 (China); Chang, Y.-Y. [Electronics Research and Service Organization (ERSO), Industrial Technology Research Institute (ITRI), Hsinchu, Taiwan (China); Lee, C.-C. [Electronics Research and Service Organization (ERSO), Industrial Technology Research Institute (ITRI), Hsinchu, Taiwan (China)

    2006-03-01

    In this work, combination of screen-printing process and microwave plasma enhanced chemical vapor deposition system (MPCVD) was applied to fabricate patterned carbon nanotubes (CNTs) on the cathode electrodes on glass substrates. Solution based Ni catalyst was well-mixed with Ag powders and organic binder materials to form screen printed paste. CNTs were then grown under the atmosphere of CH{sub 4}/H{sub 2} gas mixture below 550 deg. C. In the field emission measurement, the turn-on field was 3.2 V/{mu}m and uniform electron emission image was also observed.

  6. Carbon nanotube/polymer composite electrodes for flexible, attachable electrochemical DNA sensors.

    Science.gov (United States)

    Li, Jianfeng; Lee, Eun-Cheol

    2015-09-15

    All-solution-processed, easily-made, flexible multi-walled carbon nanotube (MWCNT)/polydimethylsiloxane (PDMS)-based electrodes were fabricated and used for electrochemical DNA sensors. These electrodes could serve as a recognition layer for DNA, without any surface modification, through π-π interactions between the MWCNTs and DNA, greatly simplifying the fabrication process for DNA sensors. The electrodes were directly connected to an electrochemical analyzer in the differential pulse voltammetry (DPV) and cyclic voltammetry (CV) measurements, where methylene blue was used as a redox indicator. Since neither functional groups nor probe DNA were immobilized on the surfaces of the electrodes, the sensor can be easily regenerated by washing these electrodes with water. The limit of detection was found to be 1.3 × 10(2)pM (S/N=3), with good DNA sequence differentiation ability. Fast fabrication of a DNA sensor was also achieved by cutting and attaching the MWCNT-PDMS composite electrodes at an analyte solution-containable region. Our results pave the way for developing user-fabricated easily attached DNA sensors at low costs. PMID:25950937

  7. Flexible multiwalled carbon nanotubes/conductive polymer composite electrode for supercapacitor applications

    Science.gov (United States)

    Lee, Ka Yeung Terence; Shi, HaoTian Harvey; Lian, Keryn; Naguib, Hani E.

    2015-11-01

    The electrode performance of three types of selected electrically conductive polymers (ECPs), namely polyaniline, polypyrrole (PPy) and poly(3, 4-ethylenedioxythiophene) PEDOT (PSS:PEDOT) composite with multiwalled carbon nanotubes (MWCNTs) were investigated in this study. The capacitor electrode performance has been examined in both three electrodes half-cell and two electrodes device setups. The nano-composites were fabricated via polymerization of pseudocapacitive conductive monomer onto the MWCNT surface through the in situ chemical polymerization approach. Stainless steel thin foils were used as a current collector as well as a flexible backbone. Graphite conductive ink was used as the binder with the composite powder to form a conductive electrode layer. Half-cell electrochemical study was conducted to optimize the weight proportion between MWCNT and ECP in this parametric study. Two-electrode cell electrochemical study assessed the potential performance for the device. MWCNT was found to serve as the framework for polymerization of the ECP into a tubular structure. Among the three composites, it was discovered that the PPy/MWCNT composite has superior capacitor performance up to scan rate of 500 mV s-1.

  8. Electrospray deposition of carbon nanotube thin films for flexible transparent electrodes.

    Science.gov (United States)

    Meng, Yinan; Xin, Guoqing; Nam, Jaewook; Cho, Sung Min; Chae, Heeyeop

    2013-09-01

    Flexible transparent carbon nanotube (CNT) electrodes were fabricated by electrospray deposition, a large-area scalable and cost-effective process. The carbon nanotubes were dispersed in N,N-dimethylformamide (DMF) and deposited on polyethylene terephthalate (PET) substrates by electrospray deposition process at room temperature and atmospheric pressure. Major process variables were characterized and optimized for the electrospray process development such as electric field between nozzle and substrates, CNT solution flowrate, gap between nozzle and substrates, solution concentration, solvent properties and surface temperature. The sheet resistance of the electrospray deposited CNT films were reduced by HNO3 doping process. 169 Omega/sq sheet resistance and 86% optical transmittance was achieved with low surface roughness of 1.2 nm. The films showed high flexibility and transparency, making them potential replacements of ITO or ZnO in such as solid state lighting, touch panels, and solar cells. Electrospray process is a scalable process and we believe that this process can be applied for large area carbon nanotube film formation. PMID:24205613

  9. Hybrid Multi-Walled Carbon Nanotube TiO2 Electrode Material for Next Generation Energy Storage Devices

    CERN Document Server

    Marler, Sydney

    2016-01-01

    Current supercapacitors present several distinct limitations that severely inhibit the efficiency, power, and electrical capacitance of energy storage devices. Supercapacitors present an exciting prospect that has countless applications in renewable energy storage and modern day electronic devices. In recent years the exciting development of carbon nanotubes (CNTs) has presented an advantage in electrode development. CNTs, however beneficial for their increased electrode surface area, have severe limitations regarding conductivity and electrode density. Creating a nanocomposite hybrid out of a transition metal-oxide and carbon nanotube array would help the current limitations of the modern supercapacitor. TiO2 was chosen for its common occurrence in everyday materials and promising capacitance levels. A multi-walled carbon nanotube array was grown on a SiO2 precursor via CCVD. The transition metal oxide was then deposited via RF Sputtering methods to a MWCNT array. Recharge tests and characterization were con...

  10. Glassy carbon electrodes modified with multiwalled carbon nanotubes for the determination of ascorbic acid by square-wave voltammetry

    Directory of Open Access Journals (Sweden)

    Sushil Kumar

    2012-05-01

    Full Text Available Multiwalled carbon nanotubes were used to modify the surface of a glassy carbon electrode to enhance its electroactivity. Nafion served to immobilise the carbon nanotubes on the electrode surface. The modified electrode was used to develop an analytical method for the analysis of ascorbic acid (AA by square-wave voltammetry (SWV. The oxidation of ascorbic acid at the modified glassy carbon electrode showed a peak potential at 315 mV, about 80 mV lower than that observed at the bare (unmodified electrode. The peak current was about threefold higher than the response at the bare electrode. Replicate measurements of peak currents showed good precision (3% rsd. Peak currents increased with increasing ascorbic acid concentration (dynamic range = 0.0047–5.0 mmol/L and displayed good linearity (R2 = 0.994. The limit of detection was 1.4 μmol/L AA, while the limit of quantitation was 4.7 μmol/L AA. The modified electrode was applied to the determination of the amount of ascorbic acid in four brands of commercial orange-juice products. The measured content agreed well (96–104% with the product label claim for all brands tested. Recovery tests on spiked samples of orange juice showed good recovery (99–104%. The reliability of the SWV method was validated by conducting parallel experiments based on high-performance liquid chromatography (HPLC with absorbance detection. The observed mean AA contents of the commercial orange juice samples obtained by the two methods were compared statistically and were found to have no significant difference (P = 0.05.

  11. Electroanalysis of NADH Using Conducting and Redox Active Polymer/Carbon Nanotubes Modified Electrodes-A Review

    Directory of Open Access Journals (Sweden)

    Shen-Ming Chen

    2008-01-01

    Full Text Available Past few decades, conducting and redox active polymers play a critical role in the development of transducers for biosensing. It has been evidenced by increasing numerous reports on conducting and redox active polymers incorporated electrodes for assay of biomolcules. This review highlights the potential uses of electrogenerated polymer modified electrodes and polymer/carbon nanotubes composite modified electrodes for electroanalysis of reduced form of nicotinamide adenine dinuceltoide (NADH. In addition, carbon electrodes modified with organic and inorganic materials as modifier have been discussed in detail for the quantification of NADH based on mediator or mediator-less methods.

  12. In situ functionalisation of mesoporous carbon electrodes with carbon nanotubes for proton exchange membrane fuel-cell application

    International Nuclear Information System (INIS)

    In the work presented here, an attempt is made to study the effect of different carbon supports on the mesostructural properties as well as electrochemical behaviour of Pt/carbon supports. In this respect, the functionalised samples have been synthesised by using CMK-3, nickelocene as nickel source and the chemical vapour deposition (CVD) process for growth of carbon nanotubes. The platinum catalysts (Pt 20 wt.%) were obtained through a conventional wet impregnation method. All the materials have been characterised by XRD (small- and high-) angle, N2 adsorption–desorption isotherms, high-resolution transmission electron microscopy and high-resolution field emission scanning electron microscopy. The results showed that the mesostructural structure had been partially destroyed by functionalisation of CMK-3 with NiO and multiwalled carbon nanotubes (MWCNTs). Moreover, wide-angle X-ray diffraction (WAXRD) studies revealed the formation of smaller platinum crystallite sizes compared to Vulcan-supported samples. Furthermore, electrochemical evaluation indicates that CMK-3–CNT–20Pt gives a specific surface area of 58.9 m2 g−1. Finally, the polarisation curves for the fabricated membrane electrode assemblies (MEAs) with Pt loading of 0.5 mg cm−2 demonstrated that the CMK-3–CNT–20Pt catalyst shows better performance than industrial catalysts and even Vulcan–40% Pt. - Highlights: • In situ functionalisation of ordered mesoporous carbon with carbon nanotubes. • Novel electrocatalytic activity of functionalised mesostructured carbon. • Simultaneous effect of surface area and reactivity on electrocatalytic activity

  13. Fabrication and electrical properties of single wall carbon nanotube channel and graphene electrode based transistors; Toward all carbon electronics

    Science.gov (United States)

    Lee, Sang Wook; Seo, Miri; Na, Junhong; Kim, Yong Hyeon; Lee, Byeong-Joo; Kim, Jin-Ju; Yun, Hoyeol; Kim, Hakseong; Yoon, Ho-Ang; Kim, Keun Soo; Jeong, Goo-Hwan; Kim, Gyu Tae

    2014-03-01

    A transistor structure composed of an individual single-walled carbon nanotube (SWNT) channel with a graphene electrode was demonstrated. The integrated arrays of transistor devices were prepared by transferring patterned graphene electrode array on top of the pre-deposited SWNTs which were aligned along one direction. Aligned arrays of SWNTs were synthesized by thermal chemical vapor deposition (CVD) method on quartz substrate. The micro scale contact electrodes and following circuit structures were defined by photo lithography on the large area graphene produced by CVD. Both of the single and multi layer graphene were used for the electrode materials. In this presentation, the device fabrication procedure, the contact properties, and the transistor performances of the device structures were discussed. This work was supported by NRF.

  14. Vertically aligned carbon nanotube electrodes for high current density operating proton exchange membrane fuel cells

    Science.gov (United States)

    Murata, Shigeaki; Imanishi, Masahiro; Hasegawa, Shigeki; Namba, Ryoichi

    2014-05-01

    We successfully developed cathode electrodes for polymer electrolyte membrane fuel cells (PEMFC) that enable operation at high current densities by incorporating vertically aligned carbon nanotubes (CNTs) as the catalyst support; additionally, we prepared 236 cm2 membrane electrodes assemblies (MEAs) for vehicular use. The electrode structure improved the mass transport of reactants, i.e. oxygen, proton, electron and water, in systems performing at a 2.6 A cm-2 current density and 0.6 V with extremely low platinum (Pt) loading at the cathode (0.1 mg cm-2). The improved mass transport caused the 70 mV dec-1 Tafel slope to continue up to 1.0 A cm-2. The mass transport was improved because the pores were continuous, the catalyst support materials did not agglomerate and the catalyst layer made good electrical contact with the microporous layer. Utilizing wavy coil-shaped CNTs was also crucial. These CNTs displayed anti-agglomerative characteristics during the wet manufacturing process and maintained a continuous pore structure framing the layered catalyst structure. Because the CNTs had elastic characteristics, they might fill the space between catalyst and microporous layers to prevent flooding. However, the compressed CNTs in the cells were no longer vertically aligned. Therefore, vertically aligning the nanotubes was important during the MEA manufacturing process but was irrelevant for cell performance.

  15. Floating electrode transistor based on purified semiconducting carbon nanotubes for high source–drain voltage operation

    International Nuclear Information System (INIS)

    We report floating-electrode-based thin-film transistors (F-TFTs) based on a purified semiconducting single-walled carbon nanotube (swCNT) network for a high source–drain voltage operation. At a high source–drain voltage, a conventional swCNT-TFT exhibited poor transistor performance with a small on–off ratio, which was attributed to the reduced Schottky barrier modulation at a large bias. In the F-TFT device, an swCNT network channel was separated into a number of channels connected by floating electrodes. The F-TFTs exhibited a much higher on–off ratio than a conventional swCNT-TFT with a single channel. This work should provide an important guideline in designing swCNT-TFTs for high voltage applications such as displays. (paper)

  16. Carbon nanotube growth on a pointed bulk electrode using femtosecond laser nonlinear lithography

    Science.gov (United States)

    Nishiyama, Hiroaki; Iba, Tomohiro; Hirata, Yoshinori

    2013-11-01

    Carbon nanotube (CNT) bundles were synthesized on pointed bulk electrodes using femtosecond laser nonlinear lithography. A resist mask of 1.5 μm diameter was formed on a pointed bulk cathode by translating a laser focus three-dimensionally inside the spherical photoresist. Metal masks obtained by pattern transfers of the resists effectively suppressed CNT growth during plasma-enhanced chemical vapor deposition, resulting in synthesis of CNT bundles only at the electrode tip. Irradiation of field emission currents from the pointed cathode enables local melting and subsequent removal of anode materials. The damaged region size and the threshold voltage for this removal process were reduced by spatial limitations of emission sites using the metal mask.

  17. Fully Oriented Bilirubin Oxidase on Porphyrin-Functionalized Carbon Nanotube Electrodes for Electrocatalytic Oxygen Reduction.

    Science.gov (United States)

    Lalaoui, Noémie; Le Goff, Alan; Holzinger, Michael; Cosnier, Serge

    2015-11-16

    The efficient immobilization and orientation of bilirubin oxidase from Myrothecium verrucaria on multi-walled carbon nanotube electrodes by using π-stacked porphyrins as a direct electron-transfer promoter is reported. By comparing the use of different types of porphyrin, the rational effect of the porphyrin structure on both the immobilization and orientation of the enzyme is demonstrated. The best performances were obtained for protoporphyrin IX, which is the natural precursor of bilirubin. These electrodes exhibit full orientation of the enzyme, as confirmed by the observable non-catalytic redox system corresponding to the T1 copper center associated with pure Nernstian electrocatalytic behavior with high catalytic currents of almost 5 mA cm(-2) at neutral pH. PMID:26449635

  18. Amperometric Low-Potential Detection of Malic Acid Using Single-Wall Carbon Nanotubes Based Electrodes

    Directory of Open Access Journals (Sweden)

    Camelia Bala

    2008-03-01

    Full Text Available The electrocatalytical property of single-wall carbon nanotube (SWNTmodified electrode toward NADH detection was explored by cyclic voltammetry andamperometry techniques. The experimental results show that SWNT decrease theovervoltage required for oxidation of NADH (to 300 mV vs. Ag/AgCl and this propertymake them suitable for dehydrogenases based biosensors. The behavior of the SWNTmodified biosensor for L-malic acid was studied as an example for dehydrogenasesbiosensor. The amperometric measurements indicate that malate dehydrogenase (MDHcan be strongly adsorbed on the surface of the SWNT-modified electrode to form anapproximate monolayer film. Enzyme immobilization in Nafion membrane can increasethe biosensor stability. A linear calibration curve was obtained for L-malic acidconcentrations between 0.2 and 1mM.

  19. Flexible carbon nanotube--Cu2O hybrid electrodes for li-ion batteries.

    Science.gov (United States)

    Goyal, Anubha; Reddy, Arava L M; Ajayan, Pulickel M

    2011-06-20

    This study demonstrates the formation of a flexible and free-standing carbon nanotube-copper oxide-poly(vinylidene fluoride) (CNT-Cu(2) O-PVDF) nanocomposite and its application as an electrode-separator material for Li-ion batteries. Binder-free hybrid electrodes are obtained by conformally coating CNTs with Cu(2) O via electrodeposition and then embedding the resulting architecture into a porous poly(vinylidene fluoride-hexafluoropropylene) PVDF-HFP-SiO(2) polymer electrolyte membrane. The synergistic presence of high-capacity transition metal oxides and conductive CNTs results in twice the reversible areal capacity of 2.3 mAh cm(-2) as compared to 1.2 mAh cm(-2) for pure CNTs. PMID:21574248

  20. High-efficiency electrochemical thermal energy harvester using carbon nanotube aerogel sheet electrodes

    Science.gov (United States)

    Im, Hyeongwook; Kim, Taewoo; Song, Hyelynn; Choi, Jongho; Park, Jae Sung; Ovalle-Robles, Raquel; Yang, Hee Doo; Kihm, Kenneth D.; Baughman, Ray H.; Lee, Hong H.; Kang, Tae June; Kim, Yong Hyup

    2016-01-01

    Conversion of low-grade waste heat into electricity is an important energy harvesting strategy. However, abundant heat from these low-grade thermal streams cannot be harvested readily because of the absence of efficient, inexpensive devices that can convert the waste heat into electricity. Here we fabricate carbon nanotube aerogel-based thermo-electrochemical cells, which are potentially low-cost and relatively high-efficiency materials for this application. When normalized to the cell cross-sectional area, a maximum power output of 6.6 W m−2 is obtained for a 51 °C inter-electrode temperature difference, with a Carnot-relative efficiency of 3.95%. The importance of electrode purity, engineered porosity and catalytic surfaces in enhancing the thermocell performance is demonstrated. PMID:26837457

  1. High-efficiency electrochemical thermal energy harvester using carbon nanotube aerogel sheet electrodes

    Science.gov (United States)

    Im, Hyeongwook; Kim, Taewoo; Song, Hyelynn; Choi, Jongho; Park, Jae Sung; Ovalle-Robles, Raquel; Yang, Hee Doo; Kihm, Kenneth D.; Baughman, Ray H.; Lee, Hong H.; Kang, Tae June; Kim, Yong Hyup

    2016-02-01

    Conversion of low-grade waste heat into electricity is an important energy harvesting strategy. However, abundant heat from these low-grade thermal streams cannot be harvested readily because of the absence of efficient, inexpensive devices that can convert the waste heat into electricity. Here we fabricate carbon nanotube aerogel-based thermo-electrochemical cells, which are potentially low-cost and relatively high-efficiency materials for this application. When normalized to the cell cross-sectional area, a maximum power output of 6.6 W m-2 is obtained for a 51 °C inter-electrode temperature difference, with a Carnot-relative efficiency of 3.95%. The importance of electrode purity, engineered porosity and catalytic surfaces in enhancing the thermocell performance is demonstrated.

  2. Direct Electrochemistry of Glucose Oxidase at a Gold Electrode Modified with Single-Wall Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Yuan Zhuobin

    2003-12-01

    Full Text Available The direct electrochemistry of glucose oxidase (GOD was accomplished at a gold electrode modified with single-wall carbon nanotubes (SWNTs. A pair of welldefined redox peaks was obtained for GOD with the reduction peak potential at –0.465 V and a peak potential separation of 23 mV at pH 7.0. Both FT-IR spectra and the dependence of the reduction peak current on the scan rate revealed that GOD adsorbed onto the SWNT surfaces. The redox wave corresponds to the redox center of the flavin adenine dinucleotide(FAD of the GOD adsorbate. The electron transfer rate of GOD redox reaction was greatly enhanced at the SWNT-modified electrode. The peak potential was shown to be pH dependent. Verified by spectral methods, the specific enzyme activity of GOD adsorbates at the SWNTs appears to be retained.

  3. High-efficiency electrochemical thermal energy harvester using carbon nanotube aerogel sheet electrodes.

    Science.gov (United States)

    Im, Hyeongwook; Kim, Taewoo; Song, Hyelynn; Choi, Jongho; Park, Jae Sung; Ovalle-Robles, Raquel; Yang, Hee Doo; Kihm, Kenneth D; Baughman, Ray H; Lee, Hong H; Kang, Tae June; Kim, Yong Hyup

    2016-01-01

    Conversion of low-grade waste heat into electricity is an important energy harvesting strategy. However, abundant heat from these low-grade thermal streams cannot be harvested readily because of the absence of efficient, inexpensive devices that can convert the waste heat into electricity. Here we fabricate carbon nanotube aerogel-based thermo-electrochemical cells, which are potentially low-cost and relatively high-efficiency materials for this application. When normalized to the cell cross-sectional area, a maximum power output of 6.6 W m(-2) is obtained for a 51 °C inter-electrode temperature difference, with a Carnot-relative efficiency of 3.95%. The importance of electrode purity, engineered porosity and catalytic surfaces in enhancing the thermocell performance is demonstrated. PMID:26837457

  4. Electrochemical detection and degradation of ibuprofen from water on multi-walled carbon nanotubes-epoxy composite electrode

    Institute of Scientific and Technical Information of China (English)

    Sorina Motoc; Adriana Remes; Aniela Pop; Florica Manea; Joop Schoonman

    2013-01-01

    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-walled 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.

  5. Graphene Platelets as Morphology Tailoring Additive in Carbon Nanotube Transparent and Flexible Electrodes for Heating Applications

    Directory of Open Access Journals (Sweden)

    Grzegorz Wroblewski

    2015-01-01

    Full Text Available Flexible and transparent electrodes were fabricated with spray coating technique from paints based on multiwalled carbon nanotubes with the addition of graphene platelets. The work presents the influence of graphene platelets on the paints rheology and layers morphology, which has a strong connection to the electrooptical parameters of the electrodes. The paints rheology affects the atomization during spray coating and later the leveling of the coating on the substrate. Both technological aspects shape the morphology of the electrode and the distribution of nanoparticles in the coating. All these factors influence the sheet resistance and roughness, which is linked to the optical transmission and absorbance. In our research the electrode was applied as a transparent and elastic heating element with 68% optical transmission at 550 nm wavelength and 8.4 kΩ/□ sheet resistance. The elastic heating element was tested with a thermal camera at the 3 diverse supply voltages −20, 30, and 60 VDC. The test successfully confirmed and supported our proposed uses of elaborated electrodes.

  6. Flow injection based microfluidic device with carbon nanotube electrode for rapid salbutamol detection.

    Science.gov (United States)

    Karuwan, Chanpen; Wisitsoraat, Anurat; Maturos, Thitima; Phokharatkul, Disayut; Sappat, Assawapong; Jaruwongrungsee, Kata; Lomas, Tanom; Tuantranont, Adisorn

    2009-09-15

    A microfabicated flow injection device has been developed for in-channel electrochemical detection (ECD) of a beta-agonist, namely salbutamol. The microfluidic system consists of PDMS (polydimethylsiloxane) microchannel and electrochemical electrodes formed on glass substrate. The carbon nanotube (CNT) on gold layer as working electrode, silver as reference electrode and platinum as auxiliary electrode were deposited on a glass substrate. Silver, platinum, gold and stainless steel catalyst layers were coated by DC-sputtering. CNTs were then grown on the glass substance by thermal chemical vapor deposition (CVD) with gravity effect and water-assisted etching. 100-microm-deep and 500-microm-wide PDMS microchannels fabricated by SU-8 molding and casting were then bonded on glass substrate by oxygen plasma treatment. Flow injection and ECD of salbutamol was performed with the amperometric detection mode for in-channel detection of salbutamol. The influences of flow rate, injection volume, and detection potential on the response of current signal were optimized. Analytical characteristics, such as sensitivity, repeatability and dynamic range have been evaluated. Fast and highly sensitive detection of salbutamol have been achieved. Thus, the proposed combination of the efficient CNT electrode and miniaturized lab-on-a-chip is a powerful platform for beta-agonists detection. PMID:19615498

  7. Textile electrodes woven by carbon nanotube-graphene hybrid fibers for flexible electrochemical capacitors

    Science.gov (United States)

    Cheng, Huhu; Dong, Zelin; Hu, Chuangang; Zhao, Yang; Hu, Yue; Qu, Liangti; Chen, Nan; Dai, Liming

    2013-03-01

    Functional graphene-based fibers are promising as new types of flexible building blocks for the construction of wearable architectures and devices. Unique one-dimensional (1D) carbon nanotubes (CNTs) and 2D graphene (CNT/G) hybrid fibers with a large surface area and high electrical conductivity have been achieved by pre-intercalating graphene fibers with Fe3O4 nanoparticles for subsequent CVD growth of CNTs. The CNT/G hybrid fibers can be further woven into textile electrodes for the construction of flexible supercapacitors with a high tolerance to the repeated bending cycles. Various other applications, such as catalysis, separation, and adsorption, can be envisioned for the CNT/G hybrid fibers.Functional graphene-based fibers are promising as new types of flexible building blocks for the construction of wearable architectures and devices. Unique one-dimensional (1D) carbon nanotubes (CNTs) and 2D graphene (CNT/G) hybrid fibers with a large surface area and high electrical conductivity have been achieved by pre-intercalating graphene fibers with Fe3O4 nanoparticles for subsequent CVD growth of CNTs. The CNT/G hybrid fibers can be further woven into textile electrodes for the construction of flexible supercapacitors with a high tolerance to the repeated bending cycles. Various other applications, such as catalysis, separation, and adsorption, can be envisioned for the CNT/G hybrid fibers. Electronic supplementary information (ESI) available: Electrochemical measurement of graphene fibers. See DOI: 10.1039/c3nr00320e

  8. Low-temperature synthesis of carbon nanotubes on indium tin oxide electrodes for organic solar cells

    Directory of Open Access Journals (Sweden)

    Andrea Capasso

    2012-07-01

    Full Text Available The electrical performance of indium tin oxide (ITO coated glass was improved by including a controlled layer of carbon nanotubes directly on top of the ITO film. Multiwall carbon nanotubes (MWCNTs were synthesized by chemical vapor deposition, using ultrathin Fe layers as catalyst. The process parameters (temperature, gas flow and duration were carefully refined to obtain the appropriate size and density of MWCNTs with a minimum decrease of the light harvesting in the cell. When used as anodes for organic solar cells based on poly(3-hexylthiophene (P3HT and phenyl-C61-butyric acid methyl ester (PCBM, the MWCNT-enhanced electrodes are found to improve the charge-carrier extraction from the photoactive blend, thanks to the additional percolation paths provided by the CNTs. The work function of as-modified ITO surfaces was measured by the Kelvin probe method to be 4.95 eV, resulting in an improved matching to the highest occupied molecular orbital level of the P3HT. This is in turn expected to increase the hole transport and collection at the anode, contributing to the significant increase of current density and open-circuit voltage observed in test cells created with such MWCNT-enhanced electrodes.

  9. Serotonin sensor based on a glassy carbon electrode modified with multiwalled carbon nanotubes, chitosan and poly(p-aminobenzenesulfonate)

    International Nuclear Information System (INIS)

    A glassy carbon electrode was modified with a nanocomposite prepared from poly(p-aminobenzene sulfonic acid), multi-walled carbon nanotubes and chitosan to obtain a differential pulse voltammetric sensor for serotonin that is remarkably stable and displays enhanced current response. Its peak current (at 0.38 V vs. Ag/AgCl) varied linearly with the concentration of serotonin in the 0.1–100 μM range, and the detection limit is 80 nM (at an S/N of 3). The sensor was successfully applied to the determination of serotonin in (spiked) human blood serum. (author)

  10. Binderless Composite Electrode Monolith from Carbon Nanotube and Biomass Carbon Activated by KOH and CO2 Gas for Supercapacitor

    Science.gov (United States)

    Farma, R.; Deraman, M.; Omar, R.; Awitdrus, Ishak, M. M.; Taer, E.; Talib, I. A.

    2011-12-01

    This paper presents a method to improve the performance of supercapacitors fabricated using binderless composite electrode monolith (BCMs) from self-adhesive carbon grains (SACG) of fibers from oil palm empty fruit bunches. The BCMs were prepared from green monoliths (GMs) contain SACG, SACG treated with KOH (5 % by weight) and SACG mixed with carbon nanotubes (CNTs) (5% by weight) and KOH (5 % by weight), respectively. These GMs were carbonized at 800 ° C under N2 environment and activated by CO2 gas at 800 ° C for 1 hour. It was found that addition of KOH and CNTs produced BCMs with higher specific capacitance and smaller internal resistance, respectively. It was also found that supercapacitor cells using these BCMs as electrodes exhibited a better specific energy and specific power. The physical properties of BCMs (density, electrical conductivity, porosity, interlayer spacing, crystallite dimension and microstructure) were affected by the addition of KOH and CNTs.

  11. A pyrrole quinoline quinone glucose dehydrogenase biosensor based on screen-printed carbon paste electrodes modified by carbon nanotubes

    International Nuclear Information System (INIS)

    A carbon nanotube (CNT) modified biosensor based on oxygen-independent, pyrrole quinoline quinone glucose dehydrogenase (PQQ-GDH) for monitoring glucose was studied. The disposable amperometric biosensors based on screen-printed carbon paste electrodes are low cost and suitable for mass production. Potassium ferricyanide was immobilized on the surface of the electrodes as an electron mediator, which decreased the work potential. The biosensor showed a linear amperometric response to glucose from 1 to 35 mM, with a sensitivity of 31.0 µA mM−1 cm−2. Experimentally, the compositions of PQQ-GDH, potassium ferricyanide, CNTs and other components were evaluated and optimized. Only 2 µl of sample are needed for one test, and the response time of the sensor is 20 s. The characteristics of the biosensor were studied through cyclic voltammetry, and experimental results showed that the CNTs could facilitate the electron transfer between the enzyme and electrode surface significantly. Compared with the biosensor without carbon nanotube modification, the CNTs improved the sensitivity of the biosensor up to five times

  12. Study of enzyme biosensor based on carbon nanotubes modified electrode for detection of pesticides residue

    Institute of Scientific and Technical Information of China (English)

    Shu Ping Zhang; Lian Gang Shan; Zhen Ran Tian; Yi Zheng; Li Yi Shi; Deng Song Zhang

    2008-01-01

    The paper describes a controllable layer-by-layer (LBL) self-assembly modification technique of multi-walled carbon nanotubes(MWNTs) and poly(diallyldimethylammonium chloride) (PDDA) towards glassy carbon electrode (GCE), Acetylcholinesterase(ACHE) was immobilized directly to the modified GCE by LBL self-assembly method, the activity value of AChE was detected byusing i-t technique based on the modified Ellman method. Then the composition of carbaryl were detected by the enzyme electrodewith 0.01U activity value and the detection limit of carbaryl is 10-12 g L-1 so the enzyme biosensor showed good properties forpesticides residue detection.2008 Shu Ping Zhang. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.

  13. Electrocatalytic Study of Paracetamol at a Single-Walled Carbon Nanotube/Nickel Nanocomposite Modified Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Koh Sing Ngai

    2015-01-01

    Full Text Available A rapid, simple, and sensitive method for the electrochemical determination of paracetamol was developed. A single-walled carbon nanotube/nickel (SWCNT/Ni nanocomposite was prepared and immobilized on a glassy carbon electrode (GCE surface via mechanical attachment. This paper reports the voltammetry study on the effect of paracetamol concentration, scan rate, pH, and temperature at a SWCNT/Ni-modified electrode in the determination of paracetamol. The characterization of the SWCNT/Ni/GCE was performed by cyclic voltammetry. Variable pressure scanning electron microscopy (VPSEM and energy dispersive X-ray (EDX spectrometer were used to examine the surface morphology and elemental profile of the modified electrode, respectively. Cyclic voltammetry showed significant enhancement in peak current for the determination of paracetamol at the SWCNT/Ni-modified electrode. A linear calibration curve was obtained for the paracetamol concentration between 0.05 and 0.50 mM. The SWCNT/Ni/GCE displayed a sensitivity of 64 mA M−1 and a detection limit of 1.17 × 10−7 M in paracetamol detection. The proposed electrode can be applied for the determination of paracetamol in real pharmaceutical samples with satisfactory performance. Results indicate that electrodes modified with SWCNT and nickel nanoparticles exhibit better electrocatalytic activity towards paracetamol.

  14. Investigation of Lithium-Air Battery Discharge Product Formed on Carbon Nanotube and Nanofiber Electrodes

    Science.gov (United States)

    Mitchell, Robert Revell, III

    Carbon nanotubes have been actively investigated for integration in a wide variety of applications since their discovery over 20 years ago. Their myriad desirable material properties including exceptional mechanical strength, high thermal conductivities, large surface-to-volume ratios, and considerable electrical conductivities, which are attributable to a quantum mechanical ability to conduct electrons ballistically, have continued to motivate interest in this material system. While a variety of synthesis techniques exist, carbon nanotubes and nanofibers are most often conveniently synthesized using chemical vapor deposition (CVD), which involves their catalyzed growth from transition metal nanoparticles. Vertically-aligned nanotube and nanofiber carpets produced using CVD have been utilized in a variety of applications including those related to energy storage. Li-air (Li-O2) batteries have received much interest recently because of their very high theoretical energy densities (3200 Wh/kgLi2O2 ). which make them ideal candidates for energy storage devices for future fully-electric vehicles. During operation of a Li-air battery O2 is reduced on the surface a porous air cathode, reacting with Li-ions to form lithium peroxide (Li-O2). Unlike the intercalation reactions of Li-ion batteries, discharge in a Li-air cell is analogous to an electrodeposition process involving the nucleation and growth of the depositing species on a foreign substrate. Carbon nanofiber electrodes were synthesized on porous substrates using a chemical vapor deposition process and then assembled into Li-O2 cells. The large surface to volume ratio and low density of carbon nanofiber electrodes were found to yield a very high gravimetric energy density in Li-O 2 cells, approaching 75% of the theoretical energy density for Li 2O2. Further, the carbon nanofiber electrodes were found to be excellent platforms for conducting ex situ electron microscopy investigations of the deposition Li2O2 phase

  15. Carbon nanotube-coated macroporous sponge for microbial fuel cell electrodes

    KAUST Repository

    Xie, Xing

    2012-01-01

    The materials that are used to make electrodes and their internal structures significantly affect microbial fuel cell (MFC) performance. In this study, we describe a carbon nanotube (CNT)-sponge composite prepared by coating a sponge with CNTs. Compared to the CNT-coated textile electrodes evaluated in prior studies, CNT-sponge electrodes had lower internal resistance, greater stability, more tunable and uniform macroporous structure (pores up to 1 mm in diameter), and improved mechanical properties. The CNT-sponge composite also provided a three-dimensional scaffold that was favorable for microbial colonization and catalytic decoration. Using a batch-fed H-shaped MFC outfitted with CNT-sponge electrodes, an areal power density of 1.24 W m -2 was achieved when treating domestic wastewater. The maximum volumetric power density of a continuously fed plate-shaped MFC was 182 W m -3. To our knowledge, these are the highest values obtained to date for MFCs fed domestic wastewater: 2.5 times the previously reported maximum areal power density and 12 times the previously reported maximum volumetric power density. © 2011 The Royal Society of Chemistry.

  16. Extended width in discontinuously connected polymer-free carbon nanotubes grown between electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Wen-Teng, E-mail: wtchang@nuk.edu.tw; Yang, Fu-Siang

    2015-02-15

    Polymer-free carbon nanotubes (CNTs) grown between single-gap (SG) and interdigital-gap (IG) electrodes were used to develop miniature strain gauges. The strain and stress of the gauges were approximated according to the distance lift of a screw on a cantilever silicon substrate. In our preliminary study, electrical characterization indicated the gauge factors (GFs) of SG and IG devices to be approximately 36 and 1500, respectively. This result suggests that an extended width in IG electrodes, generating a larger amount of CNTs, provides a smaller minimum tunneling distance than does the width in SG electrodes. The distance shift under a small distance is expected to generate a high ratio of tunneling resistance change. The sparser and denser distributions of CNTs in SG and IG electrodes probably caused the gauges to exhibit capacitive and inductive features, respectively. Despite having substantial GFs, the gauge may require improvement in packaging to resist environmental effects and the growth of homogeneous CNTs and, thus, be reproducible.

  17. Gold nanoparticle-coated multiwall carbon nanotube-modified electrode for electrochemical determination of methyl parathion

    International Nuclear Information System (INIS)

    We report on an electrochemical sensor for the determination of methyl parathion. It is based on an electrode modified with multi-walled carbon nanotubes that were covered with gold nanoparticles (Au-NPs). The vertically aligned array of MWCNTs on a tantalum substrate was coated with Au-NPs by overhead magnetron sputtering deposition. Scanning and transmission electron microscopy and XRD were used to characterize the Au-NP-MWCNTs composite. Cyclic voltammetry and differential pulse voltammetry were employed to evaluate the suitability of the new electrode for the determination of methyl parathion. Under the optimal conditions, the current response of the electrode to methyl parathion is linear in the range from 0.50 to 16.0 mg mL-1, with a detection limit of 50 μg mL-1 (signal/noise = 3), and the sensitivity is 4.5 times better than that of the plain MWCNTs electrode. We conclude that this method represents a simple, rapid, effective and sensitive approach for the detection of methyl parathion. (author)

  18. Flexible organic light-emitting diodes with transparent carbon nanotube electrodes: problems and solutions

    International Nuclear Information System (INIS)

    We study in detail here the application of transparent, conductive carbon single-wall nanotube (SWNT) networks as electrodes in flexible organic light-emitting diodes (FOLEDs). Overall comparisons of these networks to the commonly used electrodes poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and indium tin oxide (ITO) are made, and SWNT networks are shown to have excellent optical and superior mechanical properties. The effects of protruding nanotubes, rough surface morphology, and SWNT network-adjacent layer dewetting are shown to be problematic, and approaches for addressing these issues are identified. The mechanical properties of SWNT networks and ITO are compared, and SWNT networks are shown to exhibit more durable sheet conductance under bending, which leads to bendable FOLEDs. We demonstrated FOLEDs with SWNT network anodes that exhibit outstanding light output and meet display requirements. SWNT-based FOLEDs show comparable lifetime performances to ITO-based devices. The promise and the remaining challenges for implementing SWNT networks in organic light-emitting diodes are discussed.

  19. Direct electrochemistry of glucose oxidase and electrochemical biosensing of glucose on quantum dots/carbon nanotubes electrodes.

    Science.gov (United States)

    Liu, Qing; Lu, Xianbo; Li, Jun; Yao, Xin; Li, Jinghong

    2007-06-15

    Because of their unique chemical, physical and electronic properties, Quantum dots (QDs) and carbon nanotubes (CNTs) are now extremely attractive and important nanomaterials in bioanalytical applications. In this work, CdTe QDs with the size of about 3 nm were prepared and a novel electrochemical biosensing platform of glucose based on CdTe/CNTs electrode was explored. This CdTe/CNTs electrode was prepared by first mixing CdTe QDs, CNTs, Nafion, and glucose oxidase (GOD) in appropriate amounts and then modifying this mixture on the glass carbon electrode (GC). Transmission electron microscopy (TEM) was used to observe the dispersion of CdTe QDs on carbon nanotubes and cyclic voltammetry (CV) was used to investigate the electrochemical behavior of the CdTe/CNTs electrode. A pair of well-defined quasi-reversible redox peaks of glucose oxidase were obtained at the CdTe/CNTs based enzyme electrode by direct electron transfer between the protein and the electrode. The immobilized glucose oxidase could retain bioactivity and catalyze the reduction of dissolved oxygen. Due to the synergy between the CdTe QDs and CNTs, this novel biosensing platform based on QDs/CNTs electrode responded even more sensitively than that based on GC electrode modified by CdTe QDs or CNTs alone. The inexpensive, reliable and sensitive sensing platform based on QDs/CNTs electrode provides wide potential applications in clinical, environmental, and food analysis. PMID:17416515

  20. Direct electron transfer of glucose oxidase on the carbon nanotube electrode

    Institute of Scientific and Technical Information of China (English)

    CAI Chenxin; CHEN Jing; LU Tianhong

    2004-01-01

    The direct electron transfer of glucose oxidase (Gox) immobilized onto the surface of the carbon nanotube (CNT)-modified glassy carbon (CNT/GC) electrode is reported. The direct electron transfer rate of Gox is greatly enhanced when it was immobilized onto the surface of CNT/GC electrode. Cyclic voltammetric results show a pair of well-defined and nearly sym metric redox peaks, which corresponds to the direct electron transfer of Gox, with the formal potential (E0′), which is almost independent on the scan rates, of about -0.456 V (vs. SCE) in the phosphate buffer solution (pH 6.9). The apparent heterogeneous electron transfer rate constant (ks) of Gox at the CNT/GC electrode surface is estimated to be (1.74 ± 0.42) s-1, which is much higher than that reported previously. The dependence of E0′on solution pH indicates that the direct electron transfer of Gox is a two-electron-transfer coupled with two-proton-transfer reaction process. The experimental results also demonstrate that the immobilized Gox retains its bioelectrocatalytic activity toward the oxidation of glucose. The method presented here can be easily extended to obtain the direct electrochemistry of other enzymes or proteins.

  1. Hybrid Multi-Walled Carbon Nanotube TiO2 Electrode Material for Next Generation Energy Storage Devices

    OpenAIRE

    Marler, Sydney

    2016-01-01

    Current supercapacitors present several distinct limitations that severely inhibit the efficiency, power, and electrical capacitance of energy storage devices. Supercapacitors present an exciting prospect that has countless applications in renewable energy storage and modern day electronic devices. In recent years the exciting development of carbon nanotubes (CNTs) has presented an advantage in electrode development. CNTs, however beneficial for their increased electrode surface area, have se...

  2. Glucose Biosensor Based on a Glassy Carbon Electrode Modified with Polythionine and Multiwalled Carbon Nanotubes

    OpenAIRE

    Wenwei Tang; Lei Li; Lujun Wu; Jiemin Gong; Xinping Zeng

    2014-01-01

    A novel glucose biosensor was fabricated. The first layer of the biosensor was polythionine, which was formed by the electrochemical polymerisation of the thionine monomer on a glassy carbon electrode. The remaining layers were coated with chitosan-MWCNTs, GOx, and the chitosan-PTFE film in sequence. The MWCNTs embedded in FAD were like "conductive wires" connecting FAD with electrode, reduced the distance between them and were propitious to fast direct electron transfer. Combining with good ...

  3. 14.7% efficient mesoscopic perovskite solar cells using single walled carbon nanotubes/carbon composite counter electrodes

    Science.gov (United States)

    Li, Hao; Cao, Kun; Cui, Jin; Liu, Shuangshuang; Qiao, Xianfeng; Shen, Yan; Wang, Mingkui

    2016-03-01

    A single walled carbon nanotube (SWCNT) possesses excellent hole conductivity. This work communicates an investigation of perovskite solar cells using a mesoscopic TiO2/Al2O3 structure as a framework in combination with a certain amount of SWCNT-doped graphite/carbon black counter electrode material. The CH3NH3PbI3-based device achieves a power conversion efficiency of 14.7% under AM 1.5G illumination. Detailed investigations show an increased charge collection in this device compared to that without the SWCNT additive.A single walled carbon nanotube (SWCNT) possesses excellent hole conductivity. This work communicates an investigation of perovskite solar cells using a mesoscopic TiO2/Al2O3 structure as a framework in combination with a certain amount of SWCNT-doped graphite/carbon black counter electrode material. The CH3NH3PbI3-based device achieves a power conversion efficiency of 14.7% under AM 1.5G illumination. Detailed investigations show an increased charge collection in this device compared to that without the SWCNT additive. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07347b

  4. Direct Electrochemical Oxidation of NADPH at a Low Potential on the Carbon Nanotube Modified Glassy Carbon Electrode

    Institute of Scientific and Technical Information of China (English)

    CHEN, Jing(陈静); CAI, Chen-Xin(蔡称心)

    2004-01-01

    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 5×10-7 to 1×10-3 mol/L with a detection limit of about 1×10-7 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.

  5. 'Bucky gel' of multiwalled carbon nanotubes as electrodes for high performance, flexible electric double layer capacitors.

    Science.gov (United States)

    Singh, Manoj K; Kumar, Yogesh; Hashmi, S A

    2013-11-22

    We report the preparation of a gelled form of multiwalled carbon nanotubes (MWCNTs) with an ionic liquid 1-butyl-1-methyl pyrrolidinium bis(trifluoromethane sulfonyl)imide (BMPTFSI)), referred to as 'bucky gel', to be used as binderless electrodes in electrical double layer capacitors (EDLCs). The characteristics of gelled MWCNTs are compared with pristine MWCNTs using transmission electron microscopy, x-ray diffraction and Raman studies. A gel polymer electrolyte film consisting of a blend of poly(vinylidene fluoride-co-hexafluoropropylene) and BMPTFSI, exhibiting a room temperature ionic conductivity of 1.5 × 10(-3) S cm(-1), shows its suitability as an electrolyte/separator in flexible EDLCs. The performance of EDLCs, assembled with bucky gel electrodes, using impedance spectroscopy, cyclic voltammetry and charge-discharge analyses, are compared with those fabricated with pristine MWCNT-electrodes. An improvement in specific capacitance (from 19.6 to 51.3 F g(-1)) is noted when pristine MWCNTs are replaced by gelled MWCNT-binderless electrodes. Although the rate performance of the EDLCs with gelled MWCNT-electrodes is reduced, the pulse power of the device is sufficiently high (~10.5 kW kg(-1)). The gelled electrodes offer improvements in energy and power densities from 2.8 to 8.0 Wh kg(-1) and 2.0 to 4.7 kW kg(-1), respectively. Studies indicate that the gel formation of MWCNTs with ionic liquid is an excellent route to obtain high-performance EDLCs. PMID:24157648

  6. Electrochemical oxidation of dihydronicotinamide adenine dinucleotide at nitrogen-doped carbon nanotube electrodes.

    Science.gov (United States)

    Goran, Jacob M; Favela, Carlos A; Stevenson, Keith J

    2013-10-01

    Nitrogen-doped carbon nanotubes (N-CNTs) substantially lower the overpotential necessary for dihydronicotinamide adenine dinucleotide (NADH) oxidation compared to nondoped CNTs or traditional carbon electrodes such as glassy carbon (GC). We observe a 370 mV shift in the peak potential (Ep) from GC to CNTs and another 170 mV shift from CNTs to 7.4 atom % N-CNTs in a sodium phosphate buffer solution (pH 7.0) with 2.0 mM NADH (scan rate 10 mV/s). The sensitivity of 7.4 atom % N-CNTs to NADH was measured at 0.30 ± 0.04 A M(-1) cm(-2), with a limit of detection at 1.1 ± 0.3 μM and a linear range of 70 ± 10 μM poised at a low potential of -0.32 V (vs Hg/Hg2SO4). NADH fouling, known to occur to the electrode surface during NADH oxidation, was investigated by measuring both the change in Ep and the resulting loss of electrode sensitivity. NADH degradation, known to occur in phosphate buffer, was characterized by absorbance at 340 nm and correlated with the loss of NADH electroactivity. N-CNTs are further demonstrated to be an effective platform for dehydrogenase-based biosensing by allowing glucose dehydrogenase to spontaneously adsorb onto the N-CNT surface and measuring the resulting electrode's sensitivity to glucose. The glucose biosensor had a sensitivity of 0.032 ± 0.003 A M(-1) cm(-2), a limit of detection at 6 ± 1 μM, and a linear range of 440 ± 50 μM. PMID:23991631

  7. Synthesis of carbon nanotubes by laser ablation in graphite substrate of industrial arc electrodes

    International Nuclear Information System (INIS)

    In this work, an inexpensive and simple technique for the synthesis of carbon nanotubes (CNTs) by using graphite as the target for IR laser radiation is presented. This graphite material is obtained from the recycled graphite electrode core of an electric arc furnace. The experiment was carried out in a reaction chamber in an argon atmosphere at a low pressure. For laser ablation, a Lumonics TEA CO2 laser beam (7 J; 0.05-50 μs pulse length) was used in multimode operation. Products were collected on free mica sheets. The substrates were characterized by scanning electron microscopy (SEM) and the products were characterized (collected as powder) by transmission electron microscopy (TEM). They showed significant amounts of high-quality dense filaments (CNTs) that were morphologically not aligned.

  8. Third Generation Horseradish Peroxidase Biosensor Based on Self-assembling Carbon Nanotubes to Gold Electrode Surface

    Institute of Scientific and Technical Information of China (English)

    Jing Juan XU; Gang WANG; Qing ZHANG; Xing Hua XIA; Hong Yuan CHEN

    2005-01-01

    A third-generation horseradish peroxidase (HRP) biosensor has been developed by adsorbing HRP on multi-wall carbon nanotube (MWNTs) monolayer modified gold electrode surface. The assembly process was investigated by electrochemical and spectroscopic techniques.Results showed that the immobilized HRP exhibited direct electrochemical behavior toward the reduction of H2O2. The resulting biosensor shows a fast amperometric response (<2 s) to H2O2.The linear response range was from 5.0×10-7~1.0×10-5 mol/L with a detection limit of1.0×10-7mol/L. Moreover, the biosensor has a good reproducibility, and long-term stability.

  9. Nickel foam-based manganese dioxide-carbon nanotube composite electrodes for electrochemical supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jun; Zhitomirsky, Igor [Department of Materials Science and Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario (Canada); Yang, Quan Min [Inco Technical Services, Mississauga, Ontario (Canada)

    2008-12-01

    Manganese dioxide nanofibers with length ranged from 0.1 to 1 {mu}m and a diameter of about 2-4 nm were prepared by a chemical precipitation method. Composite electrodes for electrochemical supercapacitors were fabricated by impregnation of slurries of the manganese dioxide nanofibers and multiwalled carbon nanotubes (MWCNTs) into porous nickel foam current collectors. In the composite electrodes, MWCNT formed a secondary conductivity network within the nickel foam cells. Obtained composite electrodes, containing 0-20 wt.% MWCNT with total mass loading of 40 mg cm{sup -2}, showed a capacitive behavior in the 0.1-0.5 M Na{sub 2}SO{sub 4} solutions. The highest specific capacitance (SC) of 155 F g{sup -1} was obtained at a scan rate of 2 mV s{sup -1} in the 0.5 M Na{sub 2}SO{sub 4} solutions. The SC increased with increasing MWCNT content in the composite materials and increasing Na{sub 2}SO{sub 4} concentration in the solutions and decreased with increasing scan rate. (author)

  10. Nickel foam-based manganese dioxide-carbon nanotube composite electrodes for electrochemical supercapacitors

    Science.gov (United States)

    Li, Jun; Yang, Quan Min; Zhitomirsky, Igor

    Manganese dioxide nanofibers with length ranged from 0.1 to 1 μm and a diameter of about 2-4 nm were prepared by a chemical precipitation method. Composite electrodes for electrochemical supercapacitors were fabricated by impregnation of slurries of the manganese dioxide nanofibers and multiwalled carbon nanotubes (MWCNTs) into porous nickel foam current collectors. In the composite electrodes, MWCNT formed a secondary conductivity network within the nickel foam cells. Obtained composite electrodes, containing 0-20 wt.% MWCNT with total mass loading of 40 mg cm -2, showed a capacitive behavior in the 0.1-0.5 M Na 2SO 4 solutions. The highest specific capacitance (SC) of 155 F g -1 was obtained at a scan rate of 2 mV s -1 in the 0.5 M Na 2SO 4 solutions. The SC increased with increasing MWCNT content in the composite materials and increasing Na 2SO 4 concentration in the solutions and decreased with increasing scan rate.

  11. First-principles study of high-conductance DNA sequencing with carbon nanotube electrodes

    KAUST Repository

    Chen, X.

    2012-03-26

    Rapid and cost-effective DNA sequencing at the single nucleotide level might be achieved by measuring a transverse electronic current as single-stranded DNA is pulled through a nanometer-sized pore. In order to enhance the electronic coupling between the nucleotides and the electrodes and hence the current signals, we employ a pair of single-walled close-ended (6,6) carbon nanotubes (CNTs) as electrodes. We then investigate the electron transport properties of nucleotides sandwiched between such electrodes by using first-principles quantum transport theory. In particular, we consider the extreme case where the separation between the electrodes is the smallest possible that still allows the DNA translocation. The benzene-like ring at the end cap of the CNT can strongly couple with the nucleobases and therefore it can both reduce conformational fluctuations and significantly improve the conductance. As such, when the electrodes are closely spaced, the nucleobases can pass through only with their base plane parallel to the plane of CNT end caps. The optimal molecular configurations, at which the nucleotides strongly couple to the CNTs, and which yield the largest transmission, are first identified. These correspond approximately to the lowest energy configurations. Then the electronic structures and the electron transport of these optimal configurations are analyzed. The typical tunneling currents are of the order of 50 nA for voltages up to 1 V. At higher bias, where resonant transport through the molecular states is possible, the current is of the order of several μA. Below 1 V, the currents associated to the different nucleotides are consistently distinguishable, with adenine having the largest current, guanine the second largest, cytosine the third and, finally, thymine the smallest. We further calculate the transmission coefficient profiles as the nucleotides are dragged along the DNA translocation path and investigate the effects of configurational variations

  12. A flexible graphene/multiwalled carbon nanotube film as a high performance electrode material for supercapacitors

    International Nuclear Information System (INIS)

    Highlights: → A flexible graphene/multiwalled carbon nanotube (GN/MWCNT) film fabricated by flow-directed assembly and hydrazine to reduce. → The MWCNTs in the obtained composite film not only efficiently increase the basal spacing but also bridge the defects for electron transfer between GN sheets. → The freestanding GN/MWCNT film has a potential application in flexible energy storage devices. - Abstract: A flexible graphene/multiwalled carbon nanotube (GN/MWCNT) film has been fabricated by flow-directed assembly from a complex dispersion of graphite oxide (GO) and pristine MWCNTs followed by the use of gas-based hydrazine to reduce the GO into GN sheets. The GN/MWCNT (16 wt.% MWCNTs) film characterized by Fourier transformation infrared spectra, X-ray diffraction and scanning electron microscope has a layered structure with MWCNTs uniformly sandwiched between the GN sheets. The MWCNTs in the obtained composite film not only efficiently increase the basal spacing but also bridge the defects for electron transfer between GN sheets, increasing electrolyte/electrode contact area and facilitating transportation of electrolyte ion and electron into the inner region of electrode. Electrochemical data demonstrate that the GN/MWCNT film possesses a specific capacitance of 265 F g-1 at 0.1 A g-1 and a good rate capability (49% capacity retention at 50 A g-1), and displays an excellent specific capacitance retention of 97% after 2000 continuous charge/discharge cycles. The results of electrochemical measurements indicate that the freestanding GN/MWCNT film has a potential application in flexible energy storage devices.

  13. In situ functionalisation of mesoporous carbon electrodes with carbon nanotubes for proton exchange membrane fuel-cell application

    Energy Technology Data Exchange (ETDEWEB)

    Samiee, Leila, E-mail: Leila.samiee83@gmail.com; Shoghi, Fatemeh; Maghsodi, Akram

    2014-02-14

    In the work presented here, an attempt is made to study the effect of different carbon supports on the mesostructural properties as well as electrochemical behaviour of Pt/carbon supports. In this respect, the functionalised samples have been synthesised by using CMK-3, nickelocene as nickel source and the chemical vapour deposition (CVD) process for growth of carbon nanotubes. The platinum catalysts (Pt 20 wt.%) were obtained through a conventional wet impregnation method. All the materials have been characterised by XRD (small- and high-) angle, N{sub 2} adsorption–desorption isotherms, high-resolution transmission electron microscopy and high-resolution field emission scanning electron microscopy. The results showed that the mesostructural structure had been partially destroyed by functionalisation of CMK-3 with NiO and multiwalled carbon nanotubes (MWCNTs). Moreover, wide-angle X-ray diffraction (WAXRD) studies revealed the formation of smaller platinum crystallite sizes compared to Vulcan-supported samples. Furthermore, electrochemical evaluation indicates that CMK-3–CNT–20Pt gives a specific surface area of 58.9 m{sup 2} g{sup −1}. Finally, the polarisation curves for the fabricated membrane electrode assemblies (MEAs) with Pt loading of 0.5 mg cm{sup −2} demonstrated that the CMK-3–CNT–20Pt catalyst shows better performance than industrial catalysts and even Vulcan–40% Pt. - Highlights: • In situ functionalisation of ordered mesoporous carbon with carbon nanotubes. • Novel electrocatalytic activity of functionalised mesostructured carbon. • Simultaneous effect of surface area and reactivity on electrocatalytic activity.

  14. Comparative Study of Different Cross-Linking Agents for the Immobilization of Functionalized Carbon Nanotubes within a Chitosan Film Supported on a Graphite−Epoxy Composite Electrode

    OpenAIRE

    Pauliukaite, Rasa; Ghica, Mariana Emilia; Fatibello-Filho, Orlando; Brett, Christopher M. A.

    2009-01-01

    The effectiveness of immobilization of functionalized carbon nanotubes into chitosan using different cross-linking agents has been evaluated. The cross-linkers used were glyoxal (GO), glutaraldehyde (GA), epichlorohydrin (ECH), and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide together with N-hydroxysuccinimide (EDC-NHS), and the nanotubes were retained on graphite epoxy resin composite electrodes. The nanotube modified electrodes have been characterized by cyclic voltammetry (CV) and electr...

  15. Bienzymatic glucose biosensor based on co-immobilization of peroxidase and glucose oxidase on a carbon nanotubes electrode.

    Science.gov (United States)

    Zhu, Liande; Yang, Ruilan; Zhai, Jiangli; Tian, Chunyuan

    2007-11-30

    A bienzymatic glucose biosensor was proposed for selective and sensitive detection of glucose. This mediatorless biosensor was made by simultaneous immobilization of glucose oxidase (GOD) and horseradish peroxidase (HRP) in an electropolymerized pyrrole (PPy) film on a single-wall carbon nanotubes (SWNT) coated electrode. The amperometric detection of glucose was assayed by potentiostating the bienzymatic electrode at -0.1 versus Ag/AgCl to reduce the enzymatically produced H(2)O(2) with minimal interference from the coexisting electroactive compounds. The single-wall carbon nanotubes, sandwiched between the enzyme loading polypyrrole (PPy) layer and the conducting substrate (gold electrode), could efficiently promote the direct electron transfer of HRP. Operational characteristics of the bienzymatic sensor, in terms of linear range, detection limit, sensitivity, selectivity and stability, were presented in detail. PMID:17764922

  16. Supercritical fluid deposition of vanadium oxide on multi-walled carbon nanotube buckypaper for supercapacitor electrode application

    International Nuclear Information System (INIS)

    Composite electrodes were fabricated for supercapacitor applications by depositing vanadium oxide onto multi-walled carbon nanotube (MWCNT) buckypaper using supercritical fluid deposition (SFD). The deposited thin vanadium oxide layer showed amorphous structure with excellent uniformity. In aqueous KCl electrolyte, the vanadium oxide exhibited a constant pseudo-capacitance of ∼ 1024 F g-1, which was independent of the oxide material loading (up to 6.92 wt%) and voltage scan rate (up to 100 mV s-1). The highest specific electrode capacitance achieved was ∼ 85 F g-1, which was almost four times that of the pristine buckypaper electrode.

  17. A Poly(cobaloxime)/Carbon Nanotube Electrode: Freestanding Buckypaper with Polymer‐Enhanced H2‐Evolution Performance

    OpenAIRE

    Reuillard, Bertrand; Warnan, Julien; Leung, Jane J.; Wakerley, David W; Reisner, Erwin

    2016-01-01

    Abstract A freestanding H2‐evolution electrode consisting of a copolymer‐embedded cobaloxime integrated into a multiwall carbon nanotube matrix by π–π interactions is reported. This electrode is straightforward to assemble and displays high activity towards hydrogen evolution in near‐neutral pH solution under inert and aerobic conditions, with a cobalt‐based turnover number (TONCo) of up to 420. An analogous electrode with a monomeric cobaloxime showed less activity with a TONCo of only 80. T...

  18. Coatings of Different Carbon Nanotubes on Platinum Electrodes for Neuronal Devices: Preparation, Cytocompatibility and Interaction with Spiral Ganglion Cells

    Science.gov (United States)

    Schwarz, Hans-Christoph; Kranz, Katharina; Motz, Damian; Vogt, Carla; Lenarz, Thomas; Warnecke, Athanasia; Behrens, Peter

    2016-01-01

    Cochlear and deep brain implants are prominent examples for neuronal prostheses with clinical relevance. Current research focuses on the improvement of the long-term functionality and the size reduction of neural interface electrodes. A promising approach is the application of carbon nanotubes (CNTs), either as pure electrodes but especially as coating material for electrodes. The interaction of CNTs with neuronal cells has shown promising results in various studies, but these appear to depend on the specific type of neurons as well as on the kind of nanotubes. To evaluate a potential application of carbon nanotube coatings for cochlear electrodes, it is necessary to investigate the cytocompatibility of carbon nanotube coatings on platinum for the specific type of neuron in the inner ear, namely spiral ganglion neurons. In this study we have combined the chemical processing of as-delivered CNTs, the fabrication of coatings on platinum, and the characterization of the electrical properties of the coatings as well as a general cytocompatibility testing and the first cell culture investigations of CNTs with spiral ganglion neurons. By applying a modification process to three different as-received CNTs via a reflux treatment with nitric acid, long-term stable aqueous CNT dispersions free of dispersing agents were obtained. These were used to coat platinum substrates by an automated spray-coating process. These coatings enhance the electrical properties of platinum electrodes, decreasing the impedance values and raising the capacitances. Cell culture investigations of the different CNT coatings on platinum with NIH3T3 fibroblasts attest an overall good cytocompatibility of these coatings. For spiral ganglion neurons, this can also be observed but a desired positive effect of the CNTs on the neurons is absent. Furthermore, we found that the well-established DAPI staining assay does not function on the coatings prepared from single-wall nanotubes. PMID:27385031

  19. Electrochemical Characterization and Determination of Phenol and Chlorophenols by Voltammetry at Single Wall Carbon Nanotube/Poly(3,4-ethylenedioxythiophene) Modified Screen Printed Carbon Electrode

    OpenAIRE

    Negash, Negussie; Alemu, Hailemichael; Tessema, Merid

    2015-01-01

    Screen printed carbon electrode (SPCE) has been modified with single wall carbon nanotube/poly(3,4-ethylenedioxythiophene) (SWCNT/PEDOT) composites for the determination of phenol and chlorophenols (phenol, 4-chlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol). The effect of the modifiers on the electrode characteristics was evaluated and the responses were optimized for the voltammetric determination of phenol and chlorophenols. The parameters affecting the responses such as pH, sca...

  20. Electrical detection of deoxyribonucleic acid hybridization based on carbon-nanotubes/nano zirconium dioxide/chitosan-modified electrodes

    International Nuclear Information System (INIS)

    A novel and sensitive electrochemical DNA biosensor based on nanoparticles ZrO2 and multi-walled carbon nanotubes (MWNTs) for DNA immobilization and enhanced hybridization detection is described. The MWNTs/nano ZrO2/chitosan-modified glassy carbon electrode (GCE) was fabricated and oligonucleotides were immobilized to the GCE. The hybridization reaction on the electrode was monitored by differential pulse voltammetry (DPV) analysis using electroactive daunomycin as an indicator. Compared with previous DNA sensors with oligonucleotides directly incorporated on carbon electrodes, this carbon nanotube-based assay with its large surface area and good charge-transport characteristics increased DNA attachment quantity and complementary DNA detection sensitivity. The response signal increases linearly with the increase of the logarithm of the target DNA concentration in the range of 1.49 x 10-10 to 9.32 x 10-8 mol L-1 with the detection limit of 7.5 x 10-11 mol L-1 (S/N = 3). The linear regression equation is I = 32.62 + 3.037 log C DNA (mol L-1) with a correlation coefficient value of 0.9842. This is the first application of carbon nanotubes combined with nano ZrO2 to the fabrication of an electrochemical DNA biosensor with a favorable performance for the rapid detection of specific hybridization

  1. Electrocatalytic and simultaneous determination of isoproterenol, uric acid and folic acid at molybdenum (VI) complex-carbon nanotube paste electrode

    Energy Technology Data Exchange (ETDEWEB)

    Beitollahi, Hadi, E-mail: h.beitollahi@yahoo.com [Environment Department, Research Institute of Environmental Sciences, International Center for Science, High Technology and Environmental Sciences, Kerman (Iran, Islamic Republic of); Sheikhshoaie, Iran [Department of Chemistry, Faculty of Science, Shahid Bahonar University of Kerman, Kerman 76175-133 (Iran, Islamic Republic of)

    2011-11-30

    Highlights: > A molybdenum (VI) complex-carbon nanotube paste electrode have been fabricated. > This electrode reduced the oxidation potential of isoproterenol by about 175 mV. > It resolved the voltammetric waves of isoproterenol, uric acid and folic acid. - Abstract: This paper describes the development, electrochemical characterization and utilization of a novel modified molybdenum (VI) complex-carbon nanotube paste electrode for the electrocatalytic determination of isoproterenol (IP). The electrochemical profile of the proposed modified electrode was analyzed by cyclic voltammetry (CV) that showed a shift of the oxidation peak potential of IP at 175 mV to less positive value, compared with an unmodified carbon paste electrode. Differential pulse voltammetry (DPV) in 0.1 M phosphate buffer solution (PBS) at pH 7.0 was performed to determine IP in the range from 0.7 to 600.0 {mu}M, with a detection limit of 35.0 nM. Then the modified electrode was used to determine IP in an excess of uric acid (UA) and folic acid (FA) by DPV. Finally, this method was used for the determination of IP in some real samples.

  2. Electrochemical behavior of dye-linked L-proline dehydrogenase on glassy carbon electrodes modified by multi-walled carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Haitao Zheng

    2010-12-01

    Full Text Available A glassy carbon electrode (GC was modified by multi-walled carbon nanotubes (MWCNTs. The modified electrode showed a pair of redox peaks that resulted from the oxygen-containing functional groups on the nanotube surface. A recombinant thermostable dye-linked L-proline dehydrogenase (L-proDH from hyperthermophilic archaeon (Thermococcus profundus was further immobilized by physical adsorption. The modified electrode (GC/MWCNTs/L-proDH exhibited an electrocatalytic signal for L-proline compared to bare GC, GC/L-proDH and GC/MWCNTs electrodes, which suggested that the presence of MWCNTs efficiently enhances electron transfer between the active site of enzyme and electrode surface. The immobilized L-proDH showed a typical Michaelis–Menten catalytic response with lower apparent constant.

  3. Electrochemical sensors and biosensors based on redox polymer/carbon nanotube modified electrodes: a review.

    Science.gov (United States)

    Barsan, Madalina M; Ghica, M Emilia; Brett, Christopher M A

    2015-06-30

    The aim of this review is to present the contributions to the development of electrochemical sensors and biosensors based on polyphenazine or polytriphenylmethane redox polymers together with carbon nanotubes (CNT) during recent years. Phenazine polymers have been widely used in analytical applications due to their inherent charge transport properties and electrocatalytic effects. At the same time, since the first report on a CNT-based sensor, their application in the electroanalytical chemistry field has demonstrated that the unique structure and properties of CNT are ideal for the design of electrochemical (bio)sensors. We describe here that the specific combination of phenazine/triphenylmethane polymers with CNT leads to an improved performance of the resulting sensing devices, because of their complementary electrical, electrochemical and mechanical properties, and also due to synergistic effects. The preparation of polymer/CNT modified electrodes will be presented together with their electrochemical and surface characterization, with emphasis on the contribution of each component on the overall properties of the modified electrodes. Their importance in analytical chemistry is demonstrated by the numerous applications based on polymer/CNT-driven electrocatalytic effects, and their analytical performance as (bio) sensors is discussed. PMID:26041516

  4. Comparative voltammetric study and determination of carbamate pesticide residues in soil at carbon nanotubes paste electrodes

    Directory of Open Access Journals (Sweden)

    THOMMANDRU RAVEENDRANATH BAB

    2014-02-01

    Full Text Available In this investigation, the persistence of carbamate pesticides in soil samples was investigated. A simple and selective differential pulse adsorptive stripping voltammetry was selected for this investigation. Carbon nanotubes paste electrodes were used as working electrodes for differential pulse adsorptive stripping voltammetry and cyclic voltammetry. A symmetric study of the various operational parameters that affect the stripping response was carried out by differential pulse voltammetry. Peak currents were linear over the concentration range of 10-5 to 10-10 M with an accumulation potential of -0.6 V and a 70 s accumulation time with lower detection limits of 1.09 x 10-7 M, 1.07 × 10-7M, 1.09×10-7 M for chlorphropham, thiodicarb, aldicarb. The relative standard deviation (n=10 and correlation coefficient values were 1.15 %, 0.988; 1.13 %, 0.978; and 1.14 %, 0.987, respectively. Universal buffer with pH range 2.0 - 6.0 was used as sup­porting electrolyte. The solutions with uniform concentration (10-5 M were used in all deter­minations. Calculations were made by standard addition method.

  5. Voltammetric monitoring photodegradation of EDTA based on carbon nanotubes-modified electrode

    International Nuclear Information System (INIS)

    This work described a fast and sensitive voltammetric method developed for monitoring the photodegradation of ethylenediaminetetraacetic acid (EDTA). Due to the unique properties of carbon nanotubes (CNTs) such as negative charges, large surface area and excellent electron transfer ability, metal ion namely Fe3+ showed a pair of well-defined redox response peaks on the CNTs-modified electrode. When EDTA was present in the solution, the voltammetric response of Fe3+ was suppressed due to the chelating interaction between Fe3+ and EDTA. In acetate buffer solution, the concentration of EDTA was found to be inversely proportional to the decreased cathodic peak current in the range of 1.0 x 10-6 to 1.0 x 10-4 mol/L with a detection limit (3S/N) of 6.5 x 10-7 mol/L. While EDTA was degraded by UV irradiation, the voltammetric response on the CNTs-modified electrode was enhanced due to the reduced amount of EDTA species chelating with Fe3+. Accordingly, the concentration variation of EDTA during the photodegradation was analyzed. The effects of H2O2 and pH on the photodegradation of EDTA were investigated. Thus, the proposed CNTs-based voltammetry provided a useful analytical tool for studying the degradation of EDTA.

  6. Role of the Material Electrodes on Resistive Behaviour of Carbon Nanotube-Based Gas Sensors for H2S Detection

    Directory of Open Access Journals (Sweden)

    M. Lucci

    2012-01-01

    Full Text Available Miniaturized gas-sensing devices that use single-walled carbon nanotubes as active material have been fabricated using two different electrode materials, namely, Au/Cr and NbN. The resistive sensors have been assembled aligning by dielectrophoresis the nanotube bundles between 40 μm spaced Au/Cr or NbN multifinger electrodes. The sensing devices have been tested for detection of the H2S gas, in the concentration range 10–100 ppm, using N2 as carrier gas. No resistance changes were detected using sensor fabricated with NbN electrodes, whereas the response of the sensor fabricated with Au/Cr electrodes was characterized by an increase of the resistance upon gas exposure. The main performances of this sensor are a detection limit for H2S of 10 ppm and a recovery time of few minutes. The present study suggests that the mechanism involved in H2S gas detection is not a direct charge transfer between molecules and nanotubes. The hypothesis is that detection occurs through passivation of the Au surfaces by H2S molecules and modification of the contact resistance at the Au/nanotube interface.

  7. The fabrication of carbon-nanotube-coated electrodes and a field-emission-based luminescent device.

    Science.gov (United States)

    Agarwal, Sanjay; Yamini Sarada, B; Kar, Kamal K

    2010-02-10

    Tungsten substrates were coated with an Ni or Ni-Co catalyst by the electroless dip coating technique. Various carbon nanotubes were synthesized by the catalytic chemical vapor deposition (CVD) method under different growth conditions. It was observed that Ni-and Ni-Co-coated tungsten substrates give very good growth of carbon nanotubes (CNT) in terms of yield, uniformity and alignment at a growth temperature of 600 degrees C. We fabricated a field-emission-based luminescent light bulb where a tungsten wire coated with carbon nanotubes served as a cathode. Results show lower threshold voltage, better emission stability and higher luminescence for CNT cathodes in comparison with uncoated tungsten cathodes. We found that aligned-coiled carbon nanotubes are superior to straight CNTs in terms of field emission characteristics and luminescence properties. PMID:20057034

  8. Amperometric sensing of anti-HIV drug zidovudine on Ag nanofilm-multiwalled carbon nanotubes modified glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Rafati, Amir Abbas, E-mail: aa_rafati@basu.ac.ir; Afraz, Ahmadreza

    2014-06-01

    The zidovudine (ZDV) is the first drug approved for the treatment of HIV virus infection. The detection and determination of this drug are very importance in human serum because of its undesirable effects. A new ZDV sensor was fabricated on the basis of nanocomposite of silver nanofilm (Ag-NF) and multiwalled carbon nanotubes (MWCNTs) immobilized on glassy carbon electrode (GCE). The modified electrodes were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), cyclic voltammetry (CV), and linear sweep voltammetry (LSV) techniques. Results showed that the electrodeposited silver has a nanofilm structure and further electrochemical studies showed that the prepared nanocomposite has high electrocatalytic activity and is appropriate for using in sensors. The amperometric technique under optimal conditions is used for the determination of ZDV ranging from 0.1 to 400 ppm (0.37 μM–1.5 mM) with a low detection limit of 0.04 ppm (0.15 μM) (S/N = 3) and good sensitivity. The prepared sensor possessed accurate and rapid response to ZDV and shows an average recovery of 98.6% in real samples. - Highlights: • New anti-HIV drug sensor was fabricated on the basis of nanomaterials composite. • The GCE modified by prepared hydrophilic MWCNT silver nanoparticles. • Silver nanofilm electrodeposited on MWCNT/GCE and characterized by SEM, EDX, CV and LSV • Response of electrode to ZDV was thoroughly investigated by electrochemical techniques.

  9. Determination of oleuropein using multiwalled carbon nanotube modified glassy carbon electrode by adsorptive stripping square wave voltammetry.

    Science.gov (United States)

    Cittan, Mustafa; Koçak, Süleyman; Çelik, Ali; Dost, Kenan

    2016-10-01

    A multi-walled carbon nanotube modified glassy carbon electrode was used to prepare an electrochemical sensing platform for the determination of oleuropein. Results showed that, the accumulation of oleuropein on the prepared electrode takes place with the adsorption process. Electrochemical behavior of oleuropein was studied by using cyclic voltammetry. Compared to the bare GCE, the oxidation peak current of oleuropein increased about 340 times at MWCNT/GCE. Voltammetric determination of oleuropein on the surface of prepared electrode was studied using square wave voltammetry where the oxidation peak current of oleuropein was measured as an analytical signal. A calibration curve of oleuropein was performed between 0.01 and 0.70µM and a good linearity was obtained with a correlation coefficient of 0.9984. Detection and quantification limits of the method were obtained as 2.73 and 9.09nM, respectively. In addition, intra-day and inter-day precision studies indicated that the voltammetric method was sufficiently repeatable. Finally, the proposed electrochemical sensor was successfully applied to the determination of oleuropein in an olive leaf extract. Microwave-assisted extraction of oleuropein had good recovery values between 92% and 98%. The results obtained with the proposed electrochemical sensor were compared with liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. PMID:27474292

  10. Sensitive Detection of Haloperidol and Hydroxyzine at Multi-Walled Carbon Nanotubes-Modified Glassy Carbon Electrodes

    Directory of Open Access Journals (Sweden)

    Jilie Kong

    2008-03-01

    Full Text Available Haloperidol (i.e. HPD and hydroxyzine (i.e. HXY, two effective and important tranquilizers with low redox activity, were found to generate an irreversible anodic peak at about +0.86 V (vs. SCE or two anodic peaks at about +0.83 and +0.91 V in 0.05 M NaH2PO4-Na2HPO4 (pH=7.0 buffer solution with a multi-walled carbon nanotubes-modified glassy carbon electrode (i.e. MWNTs/GC, respectively. Their sensitive and quantitative measurement based on the first two anodic peaks was established under the optimum conditions. The anodic peak current was linear to HPD and HXY concentration from 1×10-7 to 2.5 ×10-5 M and 5×10-8 to 2.5 ×10-5 M, the detection limits obtained were 8×10-9 and 5×10-9 M, separately. The modified electrode exhibited some excellent characteristics including easy regeneration, high stability, good reproducibility and selectivity. The method proposed was successfully applied to the detection of HPD and HXY in drug tablets and proved to be reliable compared with ultraviolet spectrophotometry. The modified electrode was characterized by electrochemical methods.

  11. Poly-glutamic acid modified carbon nanotube-doped carbon paste electrode for sensitive detection of L-tryptophan.

    Science.gov (United States)

    Liu, Xiao; Luo, Liqiang; Ding, Yaping; Ye, Daixin

    2011-08-01

    A novel poly-glutamic acid (PGA) film modified carbon paste electrode (CPE) incorporating carbon nanotubes (CNTs) was first prepared for the determination of l-tryptophan (l-Trp). Scanning electron microscopy and Fourier transform infrared spectroscopy were applied for characterization of the surface morphology of the modified electrodes and cyclic voltammetry was used to investigate the electrochemical properties of the proposed electrode towards the oxidation of l-Trp. Optimization of the experimental parameters was performed with regard to pH, ratio of CNTs, concentration of glutamic acid, electro-polymerization cycles, accumulation time and concentration of sodium dodecylbenzene sulfonate. The linearity between the oxidation peak current and the l-Trp concentration was obtained in the range of 5.0×10(-8) to 1.0×10(-4)M with a detection limit of 1.0×10(-8)M (S/N=3) and the sensitivity was calculated to be 1143.79μA∙mM(-1)∙cm(-2). In addition, the PGA modified CPE incorporating CNTs displayed high selectivity, good stability and reproducibility, making it suitable for the routine analysis of l-Trp in clinical use. PMID:21640670

  12. Amperometric sensing of anti-HIV drug zidovudine on Ag nanofilm-multiwalled carbon nanotubes modified glassy carbon electrode

    International Nuclear Information System (INIS)

    The zidovudine (ZDV) is the first drug approved for the treatment of HIV virus infection. The detection and determination of this drug are very importance in human serum because of its undesirable effects. A new ZDV sensor was fabricated on the basis of nanocomposite of silver nanofilm (Ag-NF) and multiwalled carbon nanotubes (MWCNTs) immobilized on glassy carbon electrode (GCE). The modified electrodes were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), cyclic voltammetry (CV), and linear sweep voltammetry (LSV) techniques. Results showed that the electrodeposited silver has a nanofilm structure and further electrochemical studies showed that the prepared nanocomposite has high electrocatalytic activity and is appropriate for using in sensors. The amperometric technique under optimal conditions is used for the determination of ZDV ranging from 0.1 to 400 ppm (0.37 μM–1.5 mM) with a low detection limit of 0.04 ppm (0.15 μM) (S/N = 3) and good sensitivity. The prepared sensor possessed accurate and rapid response to ZDV and shows an average recovery of 98.6% in real samples. - Highlights: • New anti-HIV drug sensor was fabricated on the basis of nanomaterials composite. • The GCE modified by prepared hydrophilic MWCNT silver nanoparticles. • Silver nanofilm electrodeposited on MWCNT/GCE and characterized by SEM, EDX, CV and LSV • Response of electrode to ZDV was thoroughly investigated by electrochemical techniques

  13. Carbon nanotube solar cells.

    Directory of Open Access Journals (Sweden)

    Colin Klinger

    Full Text Available We present proof-of-concept all-carbon solar cells. They are made of a photoactive side of predominantly semiconducting nanotubes for photoconversion and a counter electrode made of a natural mixture of carbon nanotubes or graphite, connected by a liquid electrolyte through a redox reaction. The cells do not require rare source materials such as In or Pt, nor high-grade semiconductor processing equipment, do not rely on dye for photoconversion and therefore do not bleach, and are easy to fabricate using a spray-paint technique. We observe that cells with a lower concentration of carbon nanotubes on the active semiconducting electrode perform better than cells with a higher concentration of nanotubes. This effect is contrary to the expectation that a larger number of nanotubes would lead to more photoconversion and therefore more power generation. We attribute this to the presence of metallic nanotubes that provide a short for photo-excited electrons, bypassing the load. We demonstrate optimization strategies that improve cell efficiency by orders of magnitude. Once it is possible to make semiconducting-only carbon nanotube films, that may provide the greatest efficiency improvement.

  14. Fabrication of spintronics device by direct synthesis of single-walled carbon nanotubes from ferromagnetic electrodes

    International Nuclear Information System (INIS)

    We describe an alternative method for realizing a carbon nanotube spin field-effect transistor device by the direct synthesis of single-walled carbon nanotubes (SWNTs) on substrates by alcohol catalytic chemical vapor deposition. We observed hysteretic magnetoresistance (MR) at low temperatures due to spin-dependent transport. In these devices, the maximum ratio in resistance variation of MR was found to be 1.8%.

  15. Fabrication of spintronics device by direct synthesis of single-walled carbon nanotubes from ferromagnetic electrodes

    Directory of Open Access Journals (Sweden)

    Mohd Ambri Mohamed, Nobuhito Inami, Eiji Shikoh, Yoshiyuki Yamamoto, Hidenobu Hori and Akihiko Fujiwara

    2008-01-01

    Full Text Available We describe an alternative method for realizing a carbon nanotube spin field-effect transistor device by the direct synthesis of single-walled carbon nanotubes (SWNTs on substrates by alcohol catalytic chemical vapor deposition. We observed hysteretic magnetoresistance (MR at low temperatures due to spin-dependent transport. In these devices, the maximum ratio in resistance variation of MR was found to be 1.8%.

  16. Fabrication of the single-wall carbon nanotube compound polymer film electrode and the simultaneous electrochemical behavior of aminophenol isomers

    International Nuclear Information System (INIS)

    We describe a simple, rapid and selective voltammetry for simultaneous determination of electroactive isomers using nanometer composite electrode. The electrode was constructed by electropolymerization of 4-aminopyridine at single-wall carbon nanotubes modified glassy carbon electrode (SWNTs/POAPE). The configuration and electrochemical properties of SWNTs/POAPE were characterized by scanning electronic micrographs (SEM) and voltammetry. The SWNTs/POAPE showed an excellent electrocatalytic activity to the oxidation of aminophenol isomers and capability of determining three aminophenol isomers simultaneously. The oxidation peak potential difference between m-aminophenol and o-aminophenol was 416 mV, o-aminophenol and p-aminophenol 119 mV, indicating that the o-, m- and p-aminophenol could be identified entirely at the SWNTs/POAPE. The proposed electrode has been applied to the simultaneous voltammetric determination of aminophenol isomers in mixture without previous chemical or physical separations.

  17. Selective Electrochemical Detection of Ciprofloxacin with a Porous Nafion/Multiwalled Carbon Nanotube Composite Film Electrode.

    Science.gov (United States)

    Gayen, Pralay; Chaplin, Brian P

    2016-01-27

    This study focuses on the development of electrochemical sensors for the detection of Ciprofloxacin (CFX) in natural waters and wastewater effluents. The sensors are prepared by depositing a layer of multiwalled carbon nanotubes (MWCNTs) dispersed in a porous Nafion film on to a boron-doped diamond (BDD) electrode substrate. The porous-Nafion-MWCNT/BDD electrode enhanced detection of CFX due to selective adsorption, which was accomplished by a combination of electrostatic attraction at -SO3(-) sites in the porous Nafion film and the formation of charge assisted hydrogen bonding between CFX and -COOH MWCNT surface functional groups. By contrast, the bare BDD electrode did not show any activity for CFX oxidation. The sensors were selective for CFX detection in the presence of other antibiotics (i.e., amoxicillin) and other nontarget water constituents (i.e., Cl(-), Ca(2+), humic acid, sodium dodecylbenzenesulfonate, salicylic acid, 4-aminobenzoic acid, and 4-hydroxybenzoic acid). A limit of detection of 5 nM (S/N = 5.04 ± 0.26) in a 0.1 M KH2PO4 supporting electrolyte (pH = 4.5) was obtained using differential pulse voltammetry. The linear dynamic ranges with respect to CFX concentration were 0.005-0.05 μM and 0.05-10 μM, and the sensitivities were 41 ± 5.2 μA μM(-1) and 2.1 ± 0.22 μA μM(-1), respectively. Sensor fouling was observed at high concentrations of some organic compounds such as 1 mM 4-aminobenzoic acid and 4-hydroxybenzoic acid. However, a short cathodic treatment fully restores sensor response. The results indicate that these sensors have application in detecting CFX in natural waters and wastewater effluents. PMID:26711553

  18. Performance assessments of vertically aligned carbon nanotubes multi-electrode arrays using Cath.a-differentiated (CAD) cells

    Science.gov (United States)

    Jeong, Du Won; Jung, Jongjin; Kim, Gook Hwa; Yang, Cheol-Soo; Kim, Ju Jin; Jung, Sang Don; Lee, Jeong-O.

    2015-08-01

    In this work, Cath.a-differentiated (CAD) cells were used in place of primary neuronal cells to assess the performance of vertically aligned carbon nanotubes (VACNTs) multi-electrode arrays (MEA). To fabricate high-performance MEA, VACNTs were directly grown on graphene/Pt electrodes via plasma enhanced chemical deposition technique. Here, graphene served as an intermediate layer lowering contact resistance between VACNTs and Pt electrode. In order to lower the electrode impedance and to enhance the cell adhesion, VACNTs-MEAs were treated with UV-ozone for 20 min. Impedance of VACNTs electrode at 1 kHz frequency exhibits a reasonable value (110 kΩ) for extracellular signal recording, and the signal to noise ratio the is good enough to measure low signal amplitude (15.7). Spontaneous firing events from CAD cells were successfully measured with VACNTs MEAs that were also found to be surprisingly robust toward the biological interactions.

  19. Electrochemical detection of hydrogen peroxide at a waxed graphite electrode modified with platinum-decorated carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    SHI Qiao-cui; ZENG Wen-fang; ZHU Yunu

    2009-01-01

    Platinum-decorated carbon nanotubes (CNT-Pt) were produced by the chemical reduction method. A novel modified electrode was fabricated by intercalated CNT-Pt in the surface of waxed graphite, which provided excellent electro-catalytic activity and selectivity for both oxidation and reduction of hydrogen peroxide. The current response of the modified electrode for hydrogen peroxide was very rapid and the detection limits in amperometry are 2.5×10-6 mol/L at reduction potential and 4.8×10-6 mol/L at oxidation potential. It was desmonstrated that the electrode with high electro-activity was a suitable basic electrode for preparing enzyme electrode.

  20. Enhanced oxidation and detection of toxic ractopamine using carbon nanotube film-modified electrode

    International Nuclear Information System (INIS)

    Highlights: ► The enhanced oxidation of ractopamine on MWCNT film surface was firstly studied. ► The oxidation occurred at phenolic hydroxyl groups and transferred two electrons. ► A sensitive and effective electrochemical sensor was developed for ractopamine. ► It was used to detect ractopamine in animal tissues, the recovery was satisfactory. - Abstract: Insoluble multi-walled carbon nanotube (MWCNT) was readily dispersed into water in the presence of dihexadecyl hydrogen phosphate, and then used to modify the surface of glassy carbon electrode (GCE) by means of solvent evaporation. Scanning electron microscopy test indicated that the GCE surface was coated with uniform MWCNT film. The resulting MWCNT film-modified GCE greatly enhanced the oxidation signal of ractopamine. The oxidation mechanism was studied, and it was found that the oxidation of ractopamine occurred at two phenolic hydroxyl groups, involving two protons and two electrons. Moreover, the influences of pH value, amount of MWCNT, accumulation potential and time were investigated on the oxidation signal of ractopamine. Based on the strong enhancement effect of MWCNT, a sensitive, rapid and simple electrochemical method was developed for the detection of ractopamine. The linear range was from 50 μg L−1 to 2 mg L−1, and the detection limit was 20 μg L−1. Finally, this method was successfully used to detect the content of ractopamine in pork and liver samples, and the recovery was in the range from 93.1% to 107.2%.

  1. Dual mechanisms of DNA sequencing based on tunnelling between nitrogen-doped carbon nanotube electrodes

    Science.gov (United States)

    Kim, Han; Kim, Yong-Hoon

    2013-03-01

    The DNA sequencing approach based on the combination of nanopores and electron tunnelling has seen considerable advances in recent years, and particularly carbon nanomaterials have emerged as promising candidates to replace metal electrodes. Carrying out extensive first-principles calculations, we here show that two distinct DNA sequencing mechanisms can be achieved with different configurations of a single-type nitrogen-doped capped carbon nanotube (CNT) that has significantly enhanced transmission and chemical sensitivity over its pristine counterpart. With a small CNT-CNT gap size that induces face-on nucleobase configurations, we obtain a typical conductance ordering where the largest signal is induced from guanine due to its highest occupied molecular orbital energetic position higher than those of other bases. On the other hand, for a large CNT-CNT gap size that accommodates edge-on nucleobase configurations, we extract a completely different conductance ordering in which thymine results in the largest signal. We find that the latter novel nucleobase sensing mechanism originates from the nature of chemical connectivity between nitrogen-doped CNT caps and nucleobase functional groups that include the thymine methyl group. This work thus demonstrates the feasibility of a tunnelling-based dual-mode approach toward whole genome sequencing applications, detection of DNA base modifications, and single-molecule sensing in general.

  2. Work function engineering of ZnO electrodes by using p-type and n-type doped carbon nanotubes

    International Nuclear Information System (INIS)

    Transparent electrodes in organic electronic devices are strongly needed in order to replace indium tin oxide (ITO). Some of the best candidates are ZnO films, which have shown both good electronic properties and solution processability compatible with roll-to-roll production of the devices. We present the possibility to engineer the work function of ZnO by blending it with carbon nanotubes (CNTs). B-doped (p-type), N-doped (n-type) and undoped CNTs as well as their blends with ZnO have been characterized by atomic force microscopy (AFM), scanning Kelvin probe microscopy (SKPM) and Raman spectroscopy. The results of Raman spectroscopy demonstrate the substitutional doping of carbon nanotubes, which preserves their covalent structure although increasing the disorder within the nanotubes. The roughness and average shape of grains of ZnO when blended with the doped nanotubes have been measured by AFM. Finally, SKPM shows that the work function of the blends can be engineered from 4.4 ± 0.1 to 4.9 ± 0.1 eV according to the kind of nanotube that is blended even if only a small amount of nanotubes is added to the blend (0.08 wt%). (paper)

  3. The ohmic resistance effect for characterisation of carbon nanotube paste electrodes (CNTPEs)

    Czech Academy of Sciences Publication Activity Database

    Mikysek, T.; Stočes, M.; Švancara, I.; Ludvík, Jiří

    2012-01-01

    Roč. 2, č. 9 (2012), s. 3684-3690. ISSN 2046-2069 R&D Projects: GA MŠk LC510 Institutional research plan: CEZ:AV0Z40400503 Keywords : voltammetry * nanotubes * paste electrodes Subject RIV: CG - Electrochemistry Impact factor: 2.562, year: 2012

  4. Four probe architecture using high spatial resolution single multi-walled carbon nanotube electrodes for electrophysiology and bioimpedance monitoring of whole tissue

    Science.gov (United States)

    de Asis, Edward D.; Leung, Joseph; Wood, Sally; Nguyen, Cattien V.

    2010-03-01

    We report the application of a sensor with a multielectrode architecture consisting of four single multiwalled carbon nanotube electrodes (sMWNT electrodes) with nanotube tip diameters of approximately 30 nm to stimulation, recording, and bioimpedance characterization of whole muscle. Parallel pairs of sMWNT electrodes achieve improved stimulation efficiency from a reduction in electrode impedance and enhanced signal-to-noise ratio by detecting endogenic signals from a larger population of electrically active cells. The sensor with a four sMWNT electrode configuration can monitor changes in whole tissue bioimpedance.

  5. Screen-printed electrodes modified with carbon nanotubes or graphene for simultaneous determination of melatonin and serotonin

    International Nuclear Information System (INIS)

    Single-walled carbon nanotubes (SWCNT), multi-walled carbon nanotubes (MWCNT) and graphene have been tested as carbon allotropes for the modification of carbon screen-printed electrodes (CSPEs) to simultaneously determine melatonin (MT) and serotonin (5-HT). Two groups of CSPEs, both 4 mm in diameter, were explored: The first includes commercial SWCNT, MWCNT and graphene, the second includes SWCNT, MWCNT, graphene oxide nanoribbons and reduced nanoribbons that were drop casted on the electrodes. The carbon nanomaterials enhanced the electroactive area in the following order: CSPE carbon nanomaterials, in particular of graphene oxide nanoribbons on CSPEs, represents an excellent and disposable tool for sensing the two target molecules in even small sample volumes. Figures of merit for MT and 5-HT include (a) detection limit of 1.1 and 0.4 μM for MT and 5-HT, respectively; (b) an inter-electrode reproducibility with RSD ≤ 8 %; (c) 120 s response time, and (d) recoveries (in case of spiked samples) ranging from 94 to 103 % (with an RSD < 1 %). (author)

  6. The study of capacitive deionization behavior of a carbon nanotube electrode from the perspective of charge efficiency.

    Science.gov (United States)

    Li, Haibo; Liang, Sen; Gao, Mangmang; Li, Guolong; Li, Jin; He, Lijun

    2015-01-01

    In this work, the capacitive deionization (CDI) performance of a single-walled carbon nanotube (CNT) electrode has been studied from the point view of charge efficiency theory. It is revealed here that the charge efficiency of a CNT electrode is strongly dependent upon the cell voltage and solution concentration. Either the high cell voltage or the low ionic strength results in a high charge efficiency, implying that CDI is expected to be a promising technique for an aqueous solution with low ionic strength. Additionally, it is found that the high decay constant and high electrical double-layer capacity are beneficial to enhance electrosorption performance. PMID:25607673

  7. Amperometric nitrate biosensor based on Carbon nanotube/Polypyrrole/Nitrate reductase biofilm electrode.

    Science.gov (United States)

    Can, Faruk; Korkut Ozoner, Seyda; Ergenekon, Pinar; Erhan, Elif

    2012-01-01

    This study describes the construction and characterization of an amperometric nitrate biosensor based on the Polypyrrole (PPy)/Carbon nanotubes (CNTs) film. Nitrate reductase (NR) was both entrapped into the growing PPy film and chemically immobilized via the carboxyl groups of CNTs to the CNT/PPy film electrode. The optimum amperometric response for nitrate was obtained in 0.1 M phosphate buffer solution (PBS), pH 7.5 including 0.1 M lithium chloride and 7 mM potassium ferricyanide with an applied potential of 0.13 V (vs. Ag/AgCl, 3 M NaCl). Sensitivity was found to be 300 nA/mM in a linear range of 0.44-1.45 mM with a regression coefficient of 0.97. The biosensor response showed a higher linear range in comparison to standard nitrate analysis methods which were tested in this study and NADH based nitrate biosensors. A minimum detectable concentration of 0.17 mM (S/N=3) with a relative standard deviation (RSD) of 5.4% (n=7) was obtained for the biosensor. Phenol and glucose inhibit the electrochemical reaction strictly at a concentration of 1 μg/L and 20 mg/L, respectively. The biosensor response retained 70% of its initial response over 10 day usage period when used everyday. PMID:23177766

  8. Electrochemically reduced graphene oxide/carbon nanotubes composites as binder-free supercapacitor electrodes

    Science.gov (United States)

    Yang, Qin; Pang, Siu-Kwong; Yung, Kam-Chuen

    2016-04-01

    Binder-free composites of electrochemically reduced graphene oxide (ecrGO) and multiwalled carbon nanotubes (MWCNTs) were fabricated as supercapacitors electrodes operating in aqueous systems. GO was found to be electrochemically reduced according to the XRD and Raman data. Therefore, this facile and controllable method was applied to reduce GO in the GO/MWCNTs composites, generating ecrGO/MWCNTs composites. The ecrGO/MWCNTs composites exhibit higher specific capacitance (Csp) than ecrGO because the intercalation of MWCNTs into ecrGO sheets increases the surface areas, according to the TEM, XRD and N2 adsorption-desorption results. The composites with different mass ratios of GO to MWCNTs (10:1, 5:1, 1:1, 1:5, 1:10) were investigated. The ecrGO/MWCNTs composite (GO: MWCNTs = 5:1) showed the highest Csp from the cyclic voltammetry results at a scan rate of 10 mV s-1, and it expressed Csp of 165 F g-1 at a current density of 1 A g-1 and 93% retention after 4000 cycles of charge/discharge. When the mass ratio of GO to MWCNTs further decreases to 1:10, the Csp of the composites declines, and the ecrGO/MWCNTs composite (GO: MWCNTs = 1:10) performs a nearly pure double-layer capacitor. However, the composites containing more MWCNTs can maintain better capacitive behavior at higher rates of charge/discharge.

  9. Hybrid metal grid-polymer-carbon nanotube electrodes for high luminance organic light emitting diodes

    International Nuclear Information System (INIS)

    Organic light emitting diodes (OLEDs) incorporating grid transparent conducting electrodes (TCEs) with wide grid line spacing suffer from an inability to transfer charge carriers across the gaps in the grids to promote light emission in these areas. High luminance OLEDs fabricated using a hybrid TCE composed of poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS PH1000) or regioregular poly(3-hexylthiophene)-wrapped semiconducting single-walled carbon nanotubes (rrP3HT-SWCNT) in combination with a nanometre thin gold grid are reported here. OLEDs fabricated using the hybrid gold grid/PH1000 TCE have a luminance of 18 000 cd m−2 at 9 V; the same as the reference indium tin oxide (ITO) OLED. The gold grid/rrP3HT-SWCNT OLEDs have a lower luminance of 8260 cd m−2 at 9 V, which is likely due to a rougher rrP3HT-SWCNT surface. These results demonstrate that the hybrid gold grid/PH1000 TCE is a promising replacement for ITO in future plastic electronics applications including OLEDs and organic photovoltaics. For applications where surface roughness is not critical, e.g. electrochromic devices or discharge of static electricity, the gold grid/rrP3HT-SWCNT hybrid TCE can be employed. (paper)

  10. Immunoassay for netrin 1 via a glassy carbon electrode modified with multi-walled carbon nanotubes, thionine and gold nanoparticles

    International Nuclear Information System (INIS)

    We describe a nanostructured immunosensor for the cardiovascular biomarker netrin 1. A glassy carbon electrode was consecutively modified with multi-walled carbon nanotubes (MWCNTs), nafion (to retain the MWCNTs), thionine-coated gold nanoparticles (Thi-AuNPs), and monoclonal antibodies against netrin 1. The modified electrode was characterized by transmission electron microscopy, cyclic voltammetry, differential pulse voltammetry, UV-visible spectrophotometry and X-ray diffraction. The presence of Thi-AuNPs warrants direct and convenient immobilization of the antibody. This immunoelectrode enables netrin 1 to be determined, best at a voltage of −300 mV (vs. SCE), with a limit of detection of 30 fg mL−1 (at an S/N ratio of 3) after a 50 min incubation time. The detection range extends from 0.09 to 1800 pg∙mL−1. The method is simple, sensitive, specific and reproducible. We presume this stable and reproducible biosensor to be useful for the early detection of cardiovascular diseases. (author)

  11. Application of a multiwalled carbon nanotube-chitosan composite as an electrode in the electrosorption process for water purification.

    Science.gov (United States)

    Ma, Chih-Yu; Huang, Shih-Ching; Chou, Pei-Hsin; Den, Walter; Hou, Chia-Hung

    2016-03-01

    In this study, a multiwalled carbon nanotubes-chitosan (CNTs-CS) composite electrode was fabricated to enable water purification by electrosorption. The CNTs-CS composite electrode was shown to possess excellent capacitive behaviors and good pore accessibility by electrochemical impedance spectroscopy, galvanostatic charge-discharge, and cyclic voltammetry measurements in 1 M H2SO4 electrolyte. Moreover, the CNTs-CS composite electrode showed promising performance for capacitive water desalination. At an electric potential of 1.2 V, the electrosorption capacity and electrosorption rate of NaCl ions on the CNTs-CS composite electrode were determined to be 10.7 mg g(-1) and 0.051 min(-1), respectively, which were considerably higher than those of conventional activated electrodes. The improved electrosorption performance could be ascribed to the existence of mesopores. Additionally, the feasibility of electrosorptive removal of aniline from an aqueous solution has been demonstrated. Upon polarization at 0.6 V, the CNTs-CS composite electrode had a larger electrosorption capacity of 26.4 mg g(-1) and a higher electrosorption rate of 0.006 min(-1) for aniline compared with the open circuit condition. The enhanced adsorption resulted from the improved affinity between aniline and the electrode under electrochemical assistance involving a nonfaradic process. Consequently, the CNT-CS composite electrode, exhibiting typical double-layer capacitor behavior and a sufficient potential range, can be a potential electrode material for application in the electrosorption process. PMID:26714293

  12. Amperometric sensor for detection of bisphenol A using a pencil graphite electrode modified with polyaniline nanorods and multiwalled carbon nanotubes

    International Nuclear Information System (INIS)

    We report on a simple and highly sensitive amperometric method for the determination of bisphenol A (BPA) using pencil graphite electrodes modified with polyaniline nanorods and multiwalled carbon nanotubes. The modified electrodes display enhanced electroactivity for the oxidation of BPA compared to the unmodified pencil graphite electrode. Under optimized conditions, the sensor has a linear response to BPA in the 1. 0 and 400 μM concentration range, with a limit of detection of 10 nM (at S/N = 3). The modified electrode also has a remarkably stable response, and up to 95 injections are possible with a relative standard deviation of 4. 2% at 100 μM of BPA. Recoveries range from 86 to 102% for boiling water spiked with BPA from four brands of baby bottles. (author)

  13. A novel hydrazine electrochemical sensor based on a carbon nanotube-wired ZnO nanoflower-modified electrode

    Energy Technology Data Exchange (ETDEWEB)

    Fang Bin, E-mail: binfang_47@yahoo.com.c [Anhui Key Laboratory of Chemo-Biosensor, College of Chemistry and Materials Science, Anhui Normal University, Beijing East Road, No. 1, Wuhu 241000 (China); Zhang Cuihong; Zhang Wei; Wang Guangfeng [Anhui Key Laboratory of Chemo-Biosensor, College of Chemistry and Materials Science, Anhui Normal University, Beijing East Road, No. 1, Wuhu 241000 (China)

    2009-12-15

    ZnO nanoflowers were synthesized by a simple process (ammonia-evaporation-induced synthetic method) and were applied to the hydrazine electrochemical sensor. The prepared material was characterized by means of scanning electron microscopy (SEM) and X-ray powder diffraction (XRD) and was then immobilized onto the surface of a glassy carbon electrode (GCE) via multi-walled carbon nanotubes (MWCNTs) to obtain ZnO/MWCNTs/GCE. The potential utility of the constructed electrodes was demonstrated by applying them to the analytical determination of hydrazine concentration. An optimized limit of detection of 0.18 muM was obtained at a signal-to-noise ratio of 3 and with a fast response time (within 3 s). Additionally, the ZnO/MWCNTs/GCE exhibited a wide linear range from 0.6 to 250 muM and higher sensitivity for hydrazine than did the ZnO modified electrode without immobilization of MWCNTs.

  14. Flexible, Transparent and Conductive Carbon Nanotube Aerogels /PEDOT:PSS Electrodes created by Top-bottom Fabrication

    Science.gov (United States)

    Martinez, Patricia M.; Cerdan Pasaran, Andrea; Zakhidov, Anvar; University of Guanajuato, Mexico Collaboration

    The sheets of Carbon Nanotubes (CNT) have proven to be a good substitute for ITO. To improve their conductivity and increase optical transparency we have created composites which incorporate silver nanowires or other evaporated metals. Coating CNT/metals with PEDOT:PSS is important for creating hole transport/electron barrier layer functionality, but it is not easy to achieve using PEDOT:PSS solutions due to the hydrophobicity of CNT. We report a new top-to-bottom approach for the fabrication of highly flexible, transparent and conductive carbon nanotube-based electrodes using PDMS as a substrate. A uniform and smooth layer of approximately 50 nm of PEDOT:PSS was spin coated on top of a PDMS stamp followed by the deposition of vapor densified freestanding Multiwall Carbon Nanotube (MWNT) aerogels. An incorporation of silver nanowires, silver or Aluminum thin layer can be sprayed or evaporated on top of the freestanding MWNT aerogels in order to lower the sheet resistance even further. The PDMS substrate is drop cast on top of the configuration then the PDMS stamp is lifted-up. The PEDOT:PSS layer is selectively deposited on top of the MWNT only. The composite electrodes can be laminated on photovoltaic devices and on LEDs.

  15. Enhanced Carbon Nanotube Ultracapacitors Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed innovation utilizes carbon nanotubes (CNTs) coated with pseudo-capacitive MnO2 material as nano-composite electrode and ionic electrolyte for the...

  16. An amperometric hydrogen peroxide biosensor based on Co3O4 nanoparticles and multiwalled carbon nanotube modified glassy carbon electrode

    International Nuclear Information System (INIS)

    Highlights: • Hydrogen peroxide biosensor was constructed by combining the advantageous properties of MWCNTs and Co3O4. • Incorporating Co3O4 nanoparticles into MWCNTs/gelatin film increased the electron transfer. • Co3O4/MWCNTs/gelatin/HRP/Nafion/GCE showed strong anti-interference ability. • Hydrogen peroxide was successfully determined in disinfector with an average recovery of 100.78 ± 0.89. - Abstract: In this work a new type of hydrogen peroxide biosensor was fabricated based on the immobilization of horseradish peroxidase (HRP) by cross-linking on a glassy carbon electrode (GCE) modified with Co3O4 nanoparticles, multiwall carbon nanotubes (MWCNTs) and gelatin. The introduction of MWCNTs and Co3O4 nanoparticles not only enhanced the surface area of the modified electrode for enzyme immobilization but also facilitated the electron transfer rate, resulting in a high sensitivity of the biosensor. The fabrication process of the sensing surface was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Amperometric detection of hydrogen peroxide was investigated by holding the modified electrode at −0.30 V (vs. Ag/AgCl). The biosensor showed optimum response within 5 s at pH 7.0. The optimized biosensor showed linear response range of 7.4 × 10−7–1.9 × 10−5 M with a detection limit of 7.4 × 10−7. The applicability of the purposed biosensor was tested by detecting hydrogen peroxide in disinfector samples. The average recovery was calculated as 100.78 ± 0.89

  17. Electrooxidation of morin on glassy carbon electrode modified by carboxylated single-walled carbon nanotubes and surfactants

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • Carboxylated SWNT/GCE modified with surfactants are tested for morin determination. • The best electrocatalytic effect observed for Cetylpyridinium bromide/SWNT-COOH/GCE. • Adsorption-controlled irreversible two electron oxidation of morin is confirmed. • Sensitive differential pulse voltammetric quantification of morin is developed. • Limits of detection and quantification are 28.9 and 96 nM, respectively. - Abstract: Voltammetric characteristics of morin on glassy carbon electrode (GCE) modified by carboxylated single-walled carbon nanotubes (SWNT-COOH) and surfactants in phosphate buffer have been found. Cationic cetylpyridium bromide (CPB), nonionic Triton X100 and anionic sodium dodecylsulfate surfactants under different concentrations have been tested as modifier of SWNT-COOH/GCE. The form of CVs and oxidation potentials are not changed significantly in the presence of all type surfactants on the electrode surface that confirms negligible influence of surfactant on electron transfer rate. Morin oxidation currents are increased on surfactant-modified electrodes. The best characteristics are observed on CPB (1 μM)/SWNT-COOH/GCE when 1.8-fold increase of oxidation currents has been observed in comparison with SWNT-COOH/GCE. Mechanism of morin oxidation on CPB/SWNT-COOH/GCE is suggested on the basis of relationship between oxidation potential and pH of supporting electrolyte. Electrooxidation is adsorption-controlled irreversible two-step process with participation of one electron and one proton on each step. The linear dynamic ranges of morin determination under conditions of differential pulse voltammetry are 0.1-100 and 100-750 μM with the limits of detection and quantification 28.9 and 96.0 nM of morin, respectively. The developed approach applied for morin quantification in mulberry leaves using preliminary extraction with ethanol

  18. Evaluation of poly(3,4-ethylenedioxythiophene)/carbon nanotube neural electrode coatings for stimulation in the dorsal root ganglion

    Science.gov (United States)

    Kolarcik, Christi L.; Catt, Kasey; Rost, Erika; Albrecht, Ingrid N.; Bourbeau, Dennis; Du, Zhanhong; Kozai, Takashi D. Y.; Luo, Xiliang; Weber, Douglas J.; Cui, X. Tracy

    2015-02-01

    Objective. The dorsal root ganglion is an attractive target for implanting neural electrode arrays that restore sensory function or provide therapy via stimulation. However, penetrating microelectrodes designed for these applications are small and deliver low currents. For long-term performance of microstimulation devices, novel coating materials are needed in part to decrease impedance values at the electrode-tissue interface and to increase charge storage capacity. Approach. Conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) and multi-wall carbon nanotubes (CNTs) were coated on the electrode surface and doped with the anti-inflammatory drug, dexamethasone. Electrode characteristics and the tissue reaction around neural electrodes as a result of stimulation, coating and drug release were characterized. Hematoxylin and eosin staining along with antibodies recognizing Iba1 (microglia/macrophages), NF200 (neuronal axons), NeuN (neurons), vimentin (fibroblasts), caspase-3 (cell death) and L1 (neural cell adhesion molecule) were used. Quantitative image analyses were performed using MATLAB. Main results. Our results indicate that coated microelectrodes have lower in vitro and in vivo impedance values. Significantly less neuronal death/damage was observed with coated electrodes as compared to non-coated controls. The inflammatory response with the PEDOT/CNT-coated electrodes was also reduced. Significance. This study is the first to report on the utility of these coatings in stimulation applications. Our results indicate PEDOT/CNT coatings may be valuable additions to implantable electrodes used as therapeutic modalities.

  19. Poly(brilliant green) and poly(thionine) modified carbon nanotube coated carbon film electrodes for glucose and uric acid biosensors

    OpenAIRE

    Ghica, M. Emilia; Christopher M. A. Brett

    2014-01-01

    Poly(brilliant green) (PBG) and poly(thionine) (PTH) films have been formed on carbon film electrodes (CFEs) modified with carbon nanotubes (CNT) by electropolymerisation using potential cycling. Voltammetric and electrochemical impedance characterisation were performed. Glucose oxidase and uricase, as model enzymes, were immobilised on top of PBG/CNT/CFE and PTH/CNT/CFE for glucose and uric acid (UA) biosensing. Amperometric determination of glucose and UA was carried out in phosphate buffer...

  20. Glucose biosensor based on a glassy carbon electrode modified with polythionine and multiwalled carbon nanotubes.

    Directory of Open Access Journals (Sweden)

    Wenwei Tang

    Full Text Available A novel glucose biosensor was fabricated. The first layer of the biosensor was polythionine, which was formed by the electrochemical polymerisation of the thionine monomer on a glassy carbon electrode. The remaining layers were coated with chitosan-MWCNTs, GOx, and the chitosan-PTFE film in sequence. The MWCNTs embedded in FAD were like "conductive wires" connecting FAD with electrode, reduced the distance between them and were propitious to fast direct electron transfer. Combining with good electrical conductivity of PTH and MWCNTs, the current response was enlarged. The sensor was a parallel multi-component reaction system (PMRS and excellent electrocatalytic performance for glucose could be obtained without a mediator. The glucose sensor had a working voltage of -0.42 V, an optimum working temperature of 25°C, an optimum working pH of 7.0, and the best percentage of polytetrafluoroethylene emulsion (PTFE in the outer composite film was 2%. Under the optimised conditions, the biosensor displayed a high sensitivity of 2.80 µA mM(-1 cm(-2 and a low detection limit of 5 µM (S/N = 3, with a response time of less than 15 s and a linear range of 0.04 mM to 2.5 mM. Furthermore, the fabricated biosensor had a good selectivity, reproducibility, and long-term stability, indicating that the novel CTS+PTFE/GOx/MWCNTs/PTH composite is a promising material for immobilization of biomolecules and fabrication of third generation biosensors.

  1. Carbon Nanotube Solar Cells

    OpenAIRE

    Klinger, Colin; Patel, Yogeshwari; Postma, Henk W. Ch.

    2012-01-01

    We present proof-of-concept all-carbon solar cells. They are made of a photoactive side of predominantly semiconducting nanotubes for photoconversion and a counter electrode made of a natural mixture of carbon nanotubes or graphite, connected by a liquid electrolyte through a redox reaction. The cells do not require rare source materials such as In or Pt, nor high-grade semiconductor processing equipment, do not rely on dye for photoconversion and therefore do not bleach, and are easy to fabr...

  2. Pd–Au nanoparticle decorated carbon nanotube as a sensing layer on the surface of glassy carbon electrode for electrochemical determination of ceftazidime

    International Nuclear Information System (INIS)

    A simple electrodeposition method is employed to construct a thin film modifier of palladium–gold nanoparticles (Pd–AuNPs) decorated multi-walled carbon nanotube (MWCNT) on the surface of glassy carbon electrode (GCE). Morphology and property of Pd–AuNPs–MWCNT have been examined by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Electrochemical performance of Pd–AuNPs–MWCNT/GCE for detection of ceftazidime (CFZ) has been investigated by cyclic voltammetry (CV). This nanostructured film modified electrode effectively exhibited enhanced properties for detection of ceftazidime (CFZ). The effects of various experimental variables such as, the amount of casted MWCNT, time and potential of deposition of metal nanoparticles and the pH of the buffered solution on the electrode response are optimized. The proposed electrode showed a linear dynamic range of 0.05–50 μM and the detection limit of 1 nM for the CFZ. The modified electrode successfully supports the sensitive detection of trace amounts of the CFZ in pharmaceutical and clinical preparations. - Highlights: • A simple electrodeposition method was employed to construct a thin film modified electrode. • Palladium–gold nanoparticles are decorated on MWCNT pre-casted glassy carbon electrode. • Characterization of the electrode surface was performed by microscopic, spectroscopic and cyclic voltammetry. • The modified electrode showed enhanced properties for the detection of ceftazidime with a nano-molar detection limit. • The modified electrode was applied for detection of CFZ in pharmaceutical and clinical preparations

  3. Efficient organometallic spin filter between single-wall carbon nanotube or graphene electrodes

    DEFF Research Database (Denmark)

    Koleini, Mohammad; Paulsson, Magnus; Brandbyge, Mads

    2007-01-01

    We present a theoretical study of spin transport in a class of molecular systems consisting of an organometallic benzene-vanadium cluster placed in between graphene or single-wall carbon-nanotube-model contacts. Ab initio modeling is performed by combining spin density functional theory and...

  4. Electrochemical study and flow injection analysis of paracetamol in pharmaceutical formulations based on screen-printed electrodes and carbon nanotubes

    International Nuclear Information System (INIS)

    Acetaminophenol or paracetamol is one of the most commonly used analgesics in pharmaceutical formulations. Acetaminophen is electroactive and voltammetric mechanistic studies for the electrode processes of the acetaminophenol/N-acetyl-p-quinoneimine redox system are presented. Carbon nanotubes modified screen-printed electrodes with enhanced electron transfer properties are used for the study of the electrochemical-chemical oxidation mechanism of paracetamol at pH 2.0. Quantitative analysis of paracetamol by using its oxidation process (in a Britton-Robinson buffer solution pH 10.0) at +0.20 V (vs. an Ag pseudoreference electrode) on an untreated screen-printed carbon electrode (SPCE) was carried out. Thus, a cyclic voltammetric based reproducible determination of acetaminophen (R.S.D., 2.2%) in the range 2.5 x 10-6 M to 1 x 10-3 M, was obtained. However, when SPCEs are used as amperometric detectors coupled to a flow injection analysis (FIA) system, the detection limit achieved for paracetamol was 1 x 10-7 M, one order of magnitude lower than that obtained by voltammetric analysis. The repeatability of the amperometric detection with the same SPCE is 2% for 15 successive injections of 10-5 M acetaminophen and do not present any memory effect. Finally, the applicability of using screen-printed carbon electrodes for the electrochemical detection of paracetamol (i.e. for quality control analysis) was demonstrated by using two commercial pharmaceutical products.

  5. Electrochemical study and flow injection analysis of paracetamol in pharmaceutical formulations based on screen-printed electrodes and carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Fanjul-Bolado, Pablo [DropSens, S.L., Edificio Severo Ochoa, Campus El Cristo, 33006 Oviedo, Asturias (Spain); Lamas-Ardisana, Pedro Jose [Departamento de Quimica Fisica y Analitica, Universidad de Oviedo, Julian Claveria 8, 33006 Oviedo, Asturias (Spain); Hernandez-Santos, David [DropSens, S.L., Edificio Severo Ochoa, Campus El Cristo, 33006 Oviedo, Asturias (Spain); Costa-Garcia, Agustin, E-mail: costa@fq.uniovi.es [Departamento de Quimica Fisica y Analitica, Universidad de Oviedo, Julian Claveria 8, 33006 Oviedo, Asturias (Spain)

    2009-04-13

    Acetaminophenol or paracetamol is one of the most commonly used analgesics in pharmaceutical formulations. Acetaminophen is electroactive and voltammetric mechanistic studies for the electrode processes of the acetaminophenol/N-acetyl-p-quinoneimine redox system are presented. Carbon nanotubes modified screen-printed electrodes with enhanced electron transfer properties are used for the study of the electrochemical-chemical oxidation mechanism of paracetamol at pH 2.0. Quantitative analysis of paracetamol by using its oxidation process (in a Britton-Robinson buffer solution pH 10.0) at +0.20 V (vs. an Ag pseudoreference electrode) on an untreated screen-printed carbon electrode (SPCE) was carried out. Thus, a cyclic voltammetric based reproducible determination of acetaminophen (R.S.D., 2.2%) in the range 2.5 x 10{sup -6} M to 1 x 10{sup -3} M, was obtained. However, when SPCEs are used as amperometric detectors coupled to a flow injection analysis (FIA) system, the detection limit achieved for paracetamol was 1 x 10{sup -7} M, one order of magnitude lower than that obtained by voltammetric analysis. The repeatability of the amperometric detection with the same SPCE is 2% for 15 successive injections of 10{sup -5} M acetaminophen and do not present any memory effect. Finally, the applicability of using screen-printed carbon electrodes for the electrochemical detection of paracetamol (i.e. for quality control analysis) was demonstrated by using two commercial pharmaceutical products.

  6. Voltammetric determination of norepinephrine in the presence of acetaminophen using a novel ionic liquid/multiwall carbon nanotubes paste electrode

    International Nuclear Information System (INIS)

    A novel multiwall carbon nanotubes (MWCNTs) modified carbon ionic liquid electrode (CILE) was fabricated and used to investigate the electrochemical behavior of norepinephrine (NP). MWCNTs/CILE was prepared by mixing hydrophilic ionic liquid, 1-methyl-3-butylimidazolium bromide (MBIDZBr), with graphite powder, MWCNTs, and liquid paraffin. The fabricated MWCNTs/CILE showed great electrocatalytic ability to the oxidation of NE. The electron transfer coefficient, diffusion coefficient, and charge transfer resistant (Rct) of NE at the modified electrode were calculated. Differential pulse voltammetry of NE at the modified electrode exhibited two linear dynamic ranges with slopes of 0.0841 and 0.0231 μA/μM in the concentration ranges of 0.3 to 30.0 μM and 30.0 to 450.0 μM, respectively. The detection limit (3σ) of 0.09 μM NP was achieved. This modified electrode exhibited a good ability for well separated oxidation peaks of NE and acetaminophen (AC) in a buffer solution, pH 7.0. The proposed sensor was successfully applied for the determination of NE in human urine, pharmaceutical, and serum samples. Highlights: ► Electrochemical behavior of norepinephrine study using carbon ionic liquid electrode ► This sensor resolved the overlap response of norepinephrine and acetaminophen. ► This sensor is also used for the determination of above compounds in real samples.

  7. Voltammetric determination of norepinephrine in the presence of acetaminophen using a novel ionic liquid/multiwall carbon nanotubes paste electrode

    Energy Technology Data Exchange (ETDEWEB)

    Salmanpour, Sadegh [Department of Chemistry, Sari Branch, Islamic Azad University, Sari (Iran, Islamic Republic of); Tavana, Toktam [Department of Chemistry, Qaemshahr Branch, Islamic Azad University, Qaemshahr (Iran, Islamic Republic of); Pahlavan, Ali [Department of Physics, Science and Research Branch, Islamic Azad University, Mazandaran (Iran, Islamic Republic of); Khalilzadeh, Mohammad A., E-mail: khalilzadeh73@yahoo.com [Department of Chemistry, Science and Research Branch, Islamic Azad University, Mazandaran (Iran, Islamic Republic of); Ensafi, Ali A. [Department of Chemistry, Isfahan University of Technology, Isfahan (Iran, Islamic Republic of); Karimi-Maleh, Hassan, E-mail: h.karimi.maleh@gmail.com [Department of Chemistry, Science and Research Branch, Islamic Azad University, Mazandaran (Iran, Islamic Republic of); Beitollahi, Hadi [Environment Department, Research Institute of Environmental Sciences, International Center for Science, High Technology and Environmental Sciences, Kerman (Iran, Islamic Republic of); Kowsari, Elaheh [Department of Chemistry, Amirkabir University of Technology, No. 424, Hafez Avenue, Tehran (Iran, Islamic Republic of); Zareyee, Daryoush [Department of Chemistry, Qaemshahr Branch, Islamic Azad University, Qaemshahr (Iran, Islamic Republic of)

    2012-10-01

    A novel multiwall carbon nanotubes (MWCNTs) modified carbon ionic liquid electrode (CILE) was fabricated and used to investigate the electrochemical behavior of norepinephrine (NP). MWCNTs/CILE was prepared by mixing hydrophilic ionic liquid, 1-methyl-3-butylimidazolium bromide (MBIDZBr), with graphite powder, MWCNTs, and liquid paraffin. The fabricated MWCNTs/CILE showed great electrocatalytic ability to the oxidation of NE. The electron transfer coefficient, diffusion coefficient, and charge transfer resistant (R{sub ct}) of NE at the modified electrode were calculated. Differential pulse voltammetry of NE at the modified electrode exhibited two linear dynamic ranges with slopes of 0.0841 and 0.0231 {mu}A/{mu}M in the concentration ranges of 0.3 to 30.0 {mu}M and 30.0 to 450.0 {mu}M, respectively. The detection limit (3{sigma}) of 0.09 {mu}M NP was achieved. This modified electrode exhibited a good ability for well separated oxidation peaks of NE and acetaminophen (AC) in a buffer solution, pH 7.0. The proposed sensor was successfully applied for the determination of NE in human urine, pharmaceutical, and serum samples. Highlights: Black-Right-Pointing-Pointer Electrochemical behavior of norepinephrine study using carbon ionic liquid electrode Black-Right-Pointing-Pointer This sensor resolved the overlap response of norepinephrine and acetaminophen. Black-Right-Pointing-Pointer This sensor is also used for the determination of above compounds in real samples.

  8. Hydrogen peroxide sensor based on a stainless steel electrode coated with multi-walled carbon nanotubes modified with magnetite nanoparticles

    International Nuclear Information System (INIS)

    Multi-walled carbon nanotubes (MWCNTs) were decorated with magnetite (Fe3O4) nanoparticles and then used to modify a stainless steel electrode. The Fe3O4/MWCNTs composite was characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy and X-ray diffraction patterns. Electrochemical properties of the modified electrode revealed a substantial catalytic activity for the reduction of hydrogen peroxide. The relationship between peak current and the concentration of hydrogen peroxide was linear in the range from 0.06 mmol L-1 to 0.36 mmol L-1, and the lowest detectable concentration is 0.01 mmol.L-1 (S/N=3). The modified stainless steel electrode displays excellent stability. (author)

  9. A Poly(cobaloxime)/Carbon Nanotube Electrode: Freestanding Buckypaper with Polymer‐Enhanced H2‐Evolution Performance

    Science.gov (United States)

    Reuillard, Bertrand; Warnan, Julien; Leung, Jane J.; Wakerley, David W.

    2016-01-01

    Abstract A freestanding H2‐evolution electrode consisting of a copolymer‐embedded cobaloxime integrated into a multiwall carbon nanotube matrix by π–π interactions is reported. This electrode is straightforward to assemble and displays high activity towards hydrogen evolution in near‐neutral pH solution under inert and aerobic conditions, with a cobalt‐based turnover number (TONCo) of up to 420. An analogous electrode with a monomeric cobaloxime showed less activity with a TONCo of only 80. These results suggest that, in addition to the high surface area of the porous network of the buckypaper, the polymeric scaffold provides a stabilizing environment to the catalyst, leading to further enhancement in catalytic performance. We have therefore established that the use of a multifunctional copolymeric architecture is a viable strategy to enhance the performance of molecular electrocatalysts. PMID:26890469

  10. Amperometric nitrate biosensor based on Carbon nanotube/Polypyrrole/Nitrate reductase biofilm electrode

    International Nuclear Information System (INIS)

    This study describes the construction and characterization of an amperometric nitrate biosensor based on the Polypyrrole (PPy)/Carbon nanotubes (CNTs) film. Nitrate reductase (NR) was both entrapped into the growing PPy film and chemically immobilized via the carboxyl groups of CNTs to the CNT/PPy film electrode. The optimum amperometric response for nitrate was obtained in 0.1 M phosphate buffer solution (PBS), pH 7.5 including 0.1 M lithium chloride and 7 mM potassium ferricyanide with an applied potential of 0.13 V (vs. Ag/AgCl, 3 M NaCl). Sensitivity was found to be 300 nA/mM in a linear range of 0.44–1.45 mM with a regression coefficient of 0.97. The biosensor response showed a higher linear range in comparison to standard nitrate analysis methods which were tested in this study and NADH based nitrate biosensors. A minimum detectable concentration of 0.17 mM (S/N = 3) with a relative standard deviation (RSD) of 5.4% (n = 7) was obtained for the biosensor. Phenol and glucose inhibit the electrochemical reaction strictly at a concentration of 1 μg/L and 20 mg/L, respectively. The biosensor response retained 70% of its initial response over 10 day usage period when used everyday. - Highlights: ► K3Fe(CN)6 has been used for the first time as mediator for nitrate reductase. ► Better performance was obtained in comparison to other nitrate biosensor studies operated with various mediators. ► Analytical parameters were better than standard nitrate analysis methods.

  11. Amperometric nitrate biosensor based on Carbon nanotube/Polypyrrole/Nitrate reductase biofilm electrode

    Energy Technology Data Exchange (ETDEWEB)

    Can, Faruk; Korkut Ozoner, Seyda; Ergenekon, Pinar; Erhan, Elif, E-mail: e.erhan@gyte.edu.tr

    2012-01-01

    This study describes the construction and characterization of an amperometric nitrate biosensor based on the Polypyrrole (PPy)/Carbon nanotubes (CNTs) film. Nitrate reductase (NR) was both entrapped into the growing PPy film and chemically immobilized via the carboxyl groups of CNTs to the CNT/PPy film electrode. The optimum amperometric response for nitrate was obtained in 0.1 M phosphate buffer solution (PBS), pH 7.5 including 0.1 M lithium chloride and 7 mM potassium ferricyanide with an applied potential of 0.13 V (vs. Ag/AgCl, 3 M NaCl). Sensitivity was found to be 300 nA/mM in a linear range of 0.44-1.45 mM with a regression coefficient of 0.97. The biosensor response showed a higher linear range in comparison to standard nitrate analysis methods which were tested in this study and NADH based nitrate biosensors. A minimum detectable concentration of 0.17 mM (S/N = 3) with a relative standard deviation (RSD) of 5.4% (n = 7) was obtained for the biosensor. Phenol and glucose inhibit the electrochemical reaction strictly at a concentration of 1 {mu}g/L and 20 mg/L, respectively. The biosensor response retained 70% of its initial response over 10 day usage period when used everyday. - Highlights: Black-Right-Pointing-Pointer K{sub 3}Fe(CN){sub 6} has been used for the first time as mediator for nitrate reductase. Black-Right-Pointing-Pointer Better performance was obtained in comparison to other nitrate biosensor studies operated with various mediators. Black-Right-Pointing-Pointer Analytical parameters were better than standard nitrate analysis methods.

  12. Peroxi-coagulation degradation of C.I. Basic Yellow 2 based on carbon-PTFE and carbon nanotube-PTFE electrodes as cathode

    International Nuclear Information System (INIS)

    The electrochemical treatment of solutions containing C.I. Basic Yellow 2 (BY2) in aqueous solutions with carbon-PTFE (polytetrafluoroethylene) and carbon nanotube (CNT)-PTFE electrodes as cathode has been studied. The fabricated electrodes were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The amount of electrogenerated H2O2 on the surface of these electrodes was investigated, too. The results showed that the amount of H2O2 obtained with the CNT-PTFE electrode was nearly three times higher than that of carbon-PTFE electrode. The decolorization efficiency of BY2 in peroxi-coagulation process reached 62% and 96% in the first 10 min by carbon-PTFE and CNT-PTFE electrodes at 100 mA, respectively. The effect of operational parameters such as applied current, initial pH and initial dye concentration was studied in an attempt to reach higher decolorization efficiency. The degradation and mineralization of BY2 using CNT-PTFE electrode were followed by total organic carbon (TOC) and GC-MS analysis. The results of TOC measurements indicated that peroxi-coagulation with carbon-PTFE allowed 81% mineralization after 6 h of electrolysis; whereas peroxi-coagulation with CNT-PTFE yields 92% mineralization under the same conditions. GC-MS analysis verified the identity of intermediates and a reaction pathway based on them was proposed.

  13. Peroxi-coagulation degradation of C.I. Basic Yellow 2 based on carbon-PTFE and carbon nanotube-PTFE electrodes as cathode

    Energy Technology Data Exchange (ETDEWEB)

    Zarei, Mahmoud [Department of Applied Chemistry, University of Tabriz, Tabriz (Iran, Islamic Republic of)], E-mail: Zarei90211@yahoo.com; Salari, Darioush [Department of Applied Chemistry, University of Tabriz, Tabriz (Iran, Islamic Republic of)], E-mail: Darioush_salari@yahoo.com; Niaei, Aligoli [Department of Applied Chemistry, University of Tabriz, Tabriz (Iran, Islamic Republic of)], E-mail: Niaei@yahoo.com; Khataee, Alireza [Department of Applied Chemistry, University of Tabriz, Tabriz (Iran, Islamic Republic of)], E-mail: a_khataee@tabrizu.ac.ir

    2009-11-01

    The electrochemical treatment of solutions containing C.I. Basic Yellow 2 (BY2) in aqueous solutions with carbon-PTFE (polytetrafluoroethylene) and carbon nanotube (CNT)-PTFE electrodes as cathode has been studied. The fabricated electrodes were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The amount of electrogenerated H{sub 2}O{sub 2} on the surface of these electrodes was investigated, too. The results showed that the amount of H{sub 2}O{sub 2} obtained with the CNT-PTFE electrode was nearly three times higher than that of carbon-PTFE electrode. The decolorization efficiency of BY2 in peroxi-coagulation process reached 62% and 96% in the first 10 min by carbon-PTFE and CNT-PTFE electrodes at 100 mA, respectively. The effect of operational parameters such as applied current, initial pH and initial dye concentration was studied in an attempt to reach higher decolorization efficiency. The degradation and mineralization of BY2 using CNT-PTFE electrode were followed by total organic carbon (TOC) and GC-MS analysis. The results of TOC measurements indicated that peroxi-coagulation with carbon-PTFE allowed 81% mineralization after 6 h of electrolysis; whereas peroxi-coagulation with CNT-PTFE yields 92% mineralization under the same conditions. GC-MS analysis verified the identity of intermediates and a reaction pathway based on them was proposed.

  14. Atomic layer deposition of Co3O4 on carbon nanotubes/carbon cloth for high-capacitance and ultrastable supercapacitor electrode

    International Nuclear Information System (INIS)

    Co3O4 nanolayers have been successfully deposited on a flexible carbon nanotubes/carbon cloth (CC) substrate by atomic layer deposition. Much improved capacitance and ultra-long cycling life are achieved when the CNTs@Co3O4/CC is tested as a supercapacitor electrode. The improvement can be from the mechanically robust CC/CNTs substrate, the uniform coated high capacitance materials of Co3O4 nanoparticles, and the unique hierarchical structure. The flexible electrode of CNTs@Co3O4/CC with high areal capacitance and excellent cycling ability promises great potential for developing high-performance flexible supercapacitors. (paper)

  15. A sensitive DNA biosensor fabricated from gold nanoparticles, carbon nanotubes, and zinc oxide nanowires on a glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jie [College of Chemistry and Materials Science, Anhui Key Laboratory of Chemo-Biosensing, Anhui Normal University, Wuhu 241000 (China); Li Shuping [College of Environment Science, Anhui Normal University, Wuhu 241000 (China); Zhang Yuzhong, E-mail: zhyz65@mail.ahnu.edu.c [College of Chemistry and Materials Science, Anhui Key Laboratory of Chemo-Biosensing, Anhui Normal University, Wuhu 241000 (China)

    2010-06-01

    We outline here the fabrication of a sensitive electrochemical DNA biosensor for the detection of sequence-specific target DNA. Zinc oxide nanowires (ZnONWs) were first immobilized on the surface of a glassy carbon electrode. Multi-walled carbon nanotubes (MWCNTs) with carboxyl groups were then dropped onto the surface of the ZnONWs. Gold nanoparticles (AuNPs) were subsequently introduced to the surface of the MWNTs/ZnONWs by electrochemical deposition. A single-stranded DNA probe with a thiol group at the end (HS-ssDNA) was covalently immobilized on the surface of the AuNPs by forming an Au-S bond. Scanning electron microscopy (SEM) and cyclic voltammetry (CV) were used to investigate the film assembly process. Differential pulse voltammetry (DPV) was used to monitor DNA hybridization by measuring the electrochemical signals of [Ru(NH{sub 3}){sub 6}]{sup 3+} bounding to double-stranded DNA (dsDNA). The incorporation of ZnONWs and MWCNTs in this sensor design significantly enhances the sensitivity and the selectivity. This DNA biosensor can detect the target DNA quantitatively in the range of 1.0 x 10{sup -13} to 1.0 x 10{sup -7} M, with a detection limit of 3.5 x 10{sup -14} M (S/N = 3). In addition, the DNA biosensor exhibits excellent selectivity, even for single-mismatched DNA detection.

  16. A Sensitive Voltammetric Sensor for Determination of Glutathione Based on Multiwall Carbon Nanotubes Paste Electrode Incorporating Pyrogallol Red

    Directory of Open Access Journals (Sweden)

    Mohsen Keyvanfard

    2014-06-01

    Full Text Available A new sensitive and selective electrochemical sensor was developed for determination of glutathione (GSH at the surface of carbon paste electrode (CPE modified with multi-wall carbon nanotubes (MWCNTs as a sensor and pyrogallol red (PGR as a mediator. The mechanism of GSH electrochemical behavior at the modified electrode surface was investigated by various electrochemical techniques including chronoamperometry, cyclic voltammetry (CV and square wave voltammetry (SWV. A linear calibration curve was obtained in the concentration range of GSH of 0.3–500 μmol L–1, with a limit of detection of 0.19 μmol L–1. The method was applied to the determination of GSH in urine samples with satisfactory results.

  17. Nickel Sulfide/Graphene/Carbon Nanotube Composites as Electrode Material for the Supercapacitor Application in the Sea Flashing Signal System

    Institute of Scientific and Technical Information of China (English)

    Hailong Chen; Ji Li; Conglai Long; Tong Wei; Guoqing Ning; Jun Yan; Zhuangjun Fan

    2014-01-01

    This work presents NiS/graphene/carbon nanotube (NiS/GNS/CNT) composites as electrode material for the supercapacitor application in sea flashing signal systems. NiS nanosheets were closely anchored on the conductive GNS-CNT networks. As a result, the NiS/GNS/CNT electrode showed a high specific capacitance of 2 377 F·g-1 at 2 mV·s-1 and good cycling stability compared with the pure NiS (1 599 F·g-1 ). The enhanced electrochemical performances are attributed to the synergetic effect between the conductive carbon and the pseudo-capacitive NiS. The high performance supercapacitor may provide application in the sea flashing signal system.

  18. Simultaneous determination of cysteamine and folic acid in pharmaceutical and biological samples using modified multiwall carbon nanotube paste electrode

    Institute of Scientific and Technical Information of China (English)

    Ali Taherkhani; Hassan Karimi-Maleh; Ali A.Ensafi; Hadi Beitollahi; Ahmad Hosseini; Mohammad A.Khalilzadeh; Hassan Bagheri

    2012-01-01

    A carbon paste electrode (CPE) chemically modified with multiwall carbon nanotubes and ferrocene (FC) was used as a selective electrochemical sensor for the simultaneous determination of trace amounts of cysteamine (CA) and folic acid (FA).This modified electrode showed very efficient electrocatalytic activity for the anodic oxidation of CA.The peak current of differential pulse voltammograms of CA and FA increased linearly with their concentration in the ranges of 0.7-200 μmol/L CA and 5.0-700 μmol/L FA.The detection limits for CA and FA were 0.3 μmol/L and 2.0 μ mol/L,respectively.The diffusion coefficient (D) and transfer coefficient (α) of CA were also determined.These conditions are sufficient to allow determination of CA and FA both individually and simultaneously.

  19. Flammable and noxious gas sensing using a microtripolar electrode sensor with diameter and chirality sorted single-walled carbon nanotubes

    International Nuclear Information System (INIS)

    We report on the utilization of densely packed (∼10 SWCNTs µm−1), well-aligned arrays of single-chirality single-walled carbon nanotubes (SWCNTs) as an effective thin-film for integration into a gas sensor with a microtripolar electrode, based on field ionization by dielectrophoretic assembly from a monodisperse SWCNTs solution obtained by polymer-mediated sorting. The sensor is characterized as a field ionization electrode with sorted SWCNTs acting as both the sensing material and transducer gas concentrated directly into an electrical signal, an extractor serving to improve electric field uniformity and a collector electrode completing the current path. The gas sensing properties toward flammable and noxious gases, such as CO and H2, were investigated at room temperature. Besides the high sensitivity, the as-fabricated sensor exhibited attractive behaviors in terms of both the detection limit and a fast response, suggesting that our sensor could be used to partly circumvent the low sensing selectivity, long recovery time or irreversibility and allow for a preferential identification of the selected flammable and noxious analytes. Interestingly, the excellent sensing behaviors of the sensors based on the field ionization effect derive directly from the combined effects of the high-quality, low defect SWCNTs arrays, which leads to a small device-to-device variation in the properties and the optimization of electrode fabrication, highlighting the sensor as an appealing candidate in view of nanotube electronics. (paper)

  20. Layered manganese oxides-decorated and nickel foam-supported carbon nanotubes as advanced binder-free supercapacitor electrodes

    KAUST Repository

    Huang, Ming

    2014-12-01

    Three-dimensional carbon nanotubes@MnO2 core-shell nanostructures grown on Ni foam for binder-free capacitor electrodes have been fabricated by a floating catalyst chemical vapor deposition process and a facile hydrothermal approach. Ultrathin layered MnO2 nanosheets are uniformly coated on the surface of the carbon nanotubes (CNTs), directly grown on Ni foam. This unique well-designed binder-free electrode exhibits a high specific capacitance (325.5 F g-1 at a current density of 0.3 A g-1), good rate capability (70.7% retention), and excellent cycling stability (90.5% capacitance retention after 5000 cycles), due to the high conductivity of the close contact between CNTs and Ni foam, as well as the moderate specific surface area of the CNTs@MnO2 core-shell nanostructures. The developed synthetic strategy may provide design guidelines for constructing advanced binder-free supercapacitors electrode. © 2014 Elsevier B.V. All rights reserved.

  1. Printed transparent electrodes containing carbon nanotubes for elastic circuits applications with enhanced electrical durability under severe conditions

    International Nuclear Information System (INIS)

    Organic composites filled with nanostructures are new group of materials with unique physical properties. Carbon nanotubes (CNTs) are demonstrating good electrical and mechanical properties. This enables to produce conductive polymer-CNT thick films optically transparent, which are highly useful in production of printed electronic paper. Currently used indium tin oxide (ITO) and antimony tin oxide (ATO) films exhibit high optical transmittance with reasonable electrical conductivity, but very low resilience to mechanical stresses. This is one of the key problems in fabrication of flexible electronic displays. Current authors' achievements include fabrication of transparent electrodes obtained by screen printing technique, used for production of fully functional thick film electroluminescent structures.

  2. Binder free MoO3/multiwalled carbon nanotube thin film electrode for high energy density supercapacitors

    International Nuclear Information System (INIS)

    Highlights: • Greener alternative method for electrode preparation. • The composite electrode exhibits an energy density of 7.28 Wh kg−1. • The composite electrode exhibit high power density of 4930 W kg−1 at high current rates. • Potential energy storage material for portable and consumer electronics. - Abstract: MoO3/multiwalled carbon nanotube (MWCNT) composites were prepared by Magnetron sputtering in Ar/O2 atmosphere. This will provide a greener alternative for the fabrication of binder free composite electrode for supercapacitor applications. MWCNT provides good support for the growth of MoO3 thin films. This integrated composite electrode exhibited specific capacitance of 93 F g−1 and a corresponding energy density of 7.28 Wh kg−1 in non-aqueous electrolyte, which is almost fourfold increase compared to the bare MWCNT. Also the electrode maintains high power density of 4930 W kg−1 at high current rates, suggesting a potential energy storage material for portable and consumer electronics

  3. A novel nonenzymatic hydrogen peroxide sensor based on silver nanoparticles and ionic liquid functionalized multiwalled carbon nanotube composite modified electrode

    International Nuclear Information System (INIS)

    Highlights: • A novel nonenzymatic H2O2 sensor was constructed on AgNPs/MWCNTs-IL modified GCE. • Ionic liquid functionalized carbon nanotube was used as matrices for deposition of AgNPs effectively. • AgNPs were uniformly and less agglomerate formed on the MWCNTs-IL film. • AgNPs/MWCNTs-IL/GCE displayed good electrocatalytic activity to the reduction of H2O2 and applied to real samples. • The electrocatalytic mechanism of the constructed sensor was proposed. -- Abstract: A novel hydrogen peroxide (H2O2) sensor was fabricated by electrodepositing Ag nanoparticles (NPs) on a glassy carbon electrode (GCE) modified with ionic liquid functionalized multiwalled carbon nanotube (MWCNTs-IL) composites. The AgNPs/MWCNTs-IL composite was characterized by different methods including scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The constructed electrode exhibited good catalytic activity toward the reduction of H2O2, and obtained a linear response to logarithm of the H2O2 concentrations ranging from 1.2 × 10−8 to 4.8 × 10−6 M with a limit of detection (LOD) of 3.9 × 10−9 M. Moreover, it can be applied to real samples analysis. The excellent performance of hydrogen peroxide sensor were ascribed to the MWCNTs-IL composites being used as effective load matrix for the deposition of AgNPs and the synergistic amplification effect of the two kinds of nanomaterials – AgNPs and MWCNTs. Therefore, the catalytic mechanism of the constructed sensor was proposed. AgNPs dispersed on MWCNTs-IL were used as the catalyst for the H2O2 into O2, and the generated oxygen transported the electrode surrounding where it was detected by reduction on the electrode

  4. Transition metal doped poly(aniline-co-pyrrole)/multi-walled carbon nanotubes nanocomposite for high performance supercapacitor electrode materials

    Energy Technology Data Exchange (ETDEWEB)

    Dhibar, Saptarshi; Bhattacharya, Pallab; Hatui, Goutam; Das, C.K., E-mail: chapal12@yahoo.co.in

    2015-03-15

    Highlights: • The CuCl{sub 2} doped copolymer (PANI and PPy)/MWCNTs nanocomposite was prepared. • The nanocomposite achieved highest specific capacitance of 383 F/g at a 0.5 A/g. • Nanocomposite exhibits better energy density as well as power density. • The nanocomposite also showed better electrical conductivity at room temperature. • The nanocomposite can be used as promising electrode materials for supercapacitor. - Abstract: In this present communication, copolymer of polyaniline (PANI) and polypyrrole (PPy) that is poly(aniline-co-pyrrole) [poly(An-co-Py)], copper chloride (CuCl{sub 2}) doped poly(aniline-co-pyrrole) [poly(An-co-Py) Cu], and CuCl{sub 2} doped poly(aniline-co-pyrrole)/multi walled carbon nanotubes (MWCNTs) [poly(An-co-Py) Cu CNT] nanocomposite have been prepared by a simple and inexpensive in-situ chemical oxidative polymerization method, using ammonium persulfate (APS) as oxidant and hydrochloric acid (HCl) as dopant and investigated as high performance supercapacitor electrode materials. The possible interaction between CuCl{sub 2} with copolymers and MWCNTs was investigated by Fourier transform infrared spectroscopy (FTIR) and UV–visible spectroscopy analysis. The morphological characteristic of all the electrode materials were analyzed by Field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM) study. The electrochemical characterizations of all the electrode materials were carried out by three electrode probe method where, standard calomel electrode and platinum were used as reference and counter electrodes, respectively. Among all the electrode materials, poly(An-co-Py) Cu CNT nanocomposite achieved highest specific capacitance value of 383 F/g at 0.5 A/g scan rate. The nanocomposite showed better electrical conductivity at room temperature and also attained nonlinear current–voltage characteristic. Based on the superior electrochemical as well as other properties the as prepared

  5. High-efficiency electrochemical thermal energy harvester using carbon nanotube aerogel sheet electrodes

    OpenAIRE

    Im, Hyeongwook; Kim, Taewoo; Song, Hyelynn; Choi, Jongho; Park, Jae Sung; Ovalle-Robles, Raquel; Yang, Hee Doo; Kihm, Kenneth D.; Baughman, Ray H.; Lee, Hong H.; Kang, Tae June; Kim, Yong Hyup

    2016-01-01

    Conversion of low-grade waste heat into electricity is an important energy harvesting strategy. However, abundant heat from these low-grade thermal streams cannot be harvested readily because of the absence of efficient, inexpensive devices that can convert the waste heat into electricity. Here we fabricate carbon nanotube aerogel-based thermo-electrochemical cells, which are potentially low-cost and relatively high-efficiency materials for this application. When normalized to the cell cross-...

  6. Development of supercapacitors based on carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    马仁志; 魏秉庆; 徐才录; 梁吉; 吴德海

    2000-01-01

    Block-type electrodes made of carbon nanotubes were fabricated by different processes. The volumetric specific capacitance based on such electrodes reached 107 F/cm3, which proves carbon nanotubes to be ideal candidate materials for supercapacitors. The composite electrodes consisting of carbon nanotubes and RuO2 ·xH2O were developed by the deposition of RuO2 on the surface of carbon nanotubes. Supercapacitors based on the composite electrodes show much higher specific capacitance than those based on pure carbon nanotube ones. A specific capacitance of 600 F/g can be achieved when the weight percent of RuO2· xH2O in the composite electrodes reaches 75% . In addition , supercapacitors based on the composite electrodes show both high energy density and high power density characteristics.

  7. Development of supercapacitors based on carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Block-type electrodes made of carbon nanotubes were fabricated by different processes. The volumetric specific capacitance based on such electrodes reached 107 F/cm3, which proves carbon nanotubes to be ideal candidate materials for supercapacitors. The composite electrodes consisting of carbon nanotubes and RuO2.xH2O were developed by the deposition of RuO2 on the surface of carbon nanotubes. Supercapacitors based on the composite electrodes show much higher specific capacitance than those based on pure carbon nanotube ones. A specific capacitance of 600 F/g can be achieved when the weight percent of RuO2.xH2O in the composite electrodes reaches 75%. In addition, supercapacitors based on the composite electrodes show both high energy density and high power density characteristics.

  8. Physical process in OLED architectures with transparent carbon nanotube sheets as electrodes

    Science.gov (United States)

    Ovalle Robles, Raquel

    There has been a great deal of activity in the development of organic light emitting diodes (OLED's) and polymeric light emitting diodes (PLED's). Research in OLEDs and PLEDs have been having a significant development over the last few years towards commercialization, extended life time, stability, efficiency and new fabrication processes suitable for mass production are some of the topics. The potential for commercialization is high due to their low operating voltage (typically between 2.5 to 5 volts), their high brightness and their ease to process. They are light weight and can be flexible. Furthermore, these devices can be easily color tune to produce red, green and blue colors. Research in this type of electroluminescence devices has advanced rapidly and device prototypes now meet realistic specifications for applications. By proper device engineering these devices can achieve high electroluminescence efficiencies and lifetimes. In this research project we present several methods and procedures that we developed and use to produce OLEDs and PLEDs. We have incorporated quantum dots into OLEDs as emissive dopants that contribute to the control of the spectral distribution of emitted light allowing the production of white OLEDs using both a multilayer structure with emission from multiple layers and a bilayer structure with emission from only the quantum dots. We have also produced PLED devices with a new family of novel PPV polymers achieving high bright efficient devices. OLED structures with transparent carbon nanotube sheets, obtained by dry drawing from a CVD-grown forest have been produced. The devices shown to be very bright and the MCNT sheets are efficient hole-injecting anodes for OLEDs Also, for flexible display applications, there is a need for high strength, flexible materials which can be deposited as transparent films and can act as hole injectors for organic films. By using a hybrid ITO/MWCNT anode onto flexible substrates an enhancement of the

  9. Nitrogen-Doped Carbon Nanotube/Graphite Felts as Advanced Electrode Materials for Vanadium Redox Flow Batteries.

    Science.gov (United States)

    Wang, Shuangyin; Zhao, Xinsheng; Cochell, Thomas; Manthiram, Arumugam

    2012-08-16

    Nitrogen-doped carbon nanotubes have been grown, for the first time, on graphite felt (N-CNT/GF) by a chemical vapor deposition approach and examined as an advanced electrode for vanadium redox flow batteries (VRFBs). The unique porous structure and nitrogen doping of N-CNT/GF with increased surface area enhances the battery performance significantly. The enriched porous structure of N-CNTs on graphite felt could potentially facilitate the diffusion of electrolyte, while the N-doping could significantly contribute to the enhanced electrode performance. Specifically, the N-doping (i) modifies the electronic properties of CNT and thereby alters the chemisorption characteristics of the vanadium ions, (ii) generates defect sites that are electrochemically more active, (iii) increases the oxygen species on CNT surface, which is a key factor influencing the VRFB performance, and (iv) makes the N-CNT electrochemically more accessible than the CNT. PMID:26295765

  10. Preparation and modification of carbon nanotubes electrodes by cold plasmas processes toward the preparation of amperometric biosensors

    Energy Technology Data Exchange (ETDEWEB)

    Luais, E. [CEISAM, Universite de Nantes, CNRS, 2 rue de la Houssiniere, 44322 Nantes cedex 3 (France); IMN, Universite de Nantes, CNRS, 2 rue de la Houssiniere, 44322 Nantes cedex 3 (France); PCI, Universite du Maine, CNRS, rue Aristote, 72085 Le Mans cedex 9 (France); Thobie-Gautier, C. [CEISAM, Universite de Nantes, CNRS, 2 rue de la Houssiniere, 44322 Nantes cedex 3 (France); Tailleur, A.; Djouadi, M.-A.; Granier, A.; Tessier, P.Y. [IMN, Universite de Nantes, CNRS, 2 rue de la Houssiniere, 44322 Nantes cedex 3 (France); Debarnot, D.; Poncin-Epaillard, F. [PCI, Universite du Maine, CNRS, rue Aristote, 72085 Le Mans cedex 9 (France); Boujtita, M., E-mail: mohammed.boujtita@univ-nantes.f [CEISAM, Universite de Nantes, CNRS, 2 rue de la Houssiniere, 44322 Nantes cedex 3 (France)

    2010-11-30

    An electrochemical transducer based on vertically aligned carbon nanotubes (CNT) was prepared as a platform for biosensor development. Prior to enzyme immobilization, the CNT were treated using a microwave plasma system (CO{sub 2} and N{sub 2}/H{sub 2}) in order to functionalize the CNT surface with oxygenated and aminated groups. The morphological aspect of the electrode surface was examined by SEM and its chemical structure was also elucidated by XPS analysis. It was found out that microwave plasma system (CO{sub 2} and N{sub 2}/H{sub 2}) not only functionalizes the CNT but also permits to avoid the collapse phenomena retaining thus the alignment structure of the electrode surface. The electrochemical properties of the resulting new material based on CNT were carried out by cyclic voltammetry and were found suitable to develop high sensitive enzyme (HRP) biosensors operating on direct electron transfer process.

  11. Strong and Stable Doping of Carbon Nanotubes and Graphene by MoO x for Transparent Electrodes

    KAUST Repository

    Hellstrom, Sondra L.

    2012-07-11

    MoO x has been used for organic semiconductor doping, but it had been considered an inefficient and/or unstable dopant. We report that MoO x can strongly and stably dope carbon nanotubes and graphene. Thermally annealed MoO x-CNT composites can form durable thin film electrodes with sheet resistances of 100 ω/sq at 85% transmittance plain and 85 ω/sq at 83% transmittance with a PEDOT:PSS adlayer. Sheet resistances change less than 10% over 20 days in ambient and less than 2% with overnight heating to 300 °C in air. The MoO x can be easily deposited either by thermal evaporation or from solution-based precursors. Excellent stability coupled with high conductivity makes MoO x-CNT composites extremely attractive candidates for practical transparent electrodes. © 2012 American Chemical Society.

  12. Carbon Nanotube-based Nanohybrid Materials as Counter Electrode for Highly Efficient Dye-sensitized Solar Cells

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ji-Soo; Sim, Eun-Ju; Dao, Van-Duong; Choi, Ho-Suk [Chungnam National University, Daejeon (Korea, Republic of)

    2016-04-15

    In this study, we present an excellent approach for easily and uniformly immobilizing Pt, Au and bimetallic PtAu nanoparticles (NPs) on a multi-walled carbon nanotube (MWNT)-coated layer through dry plasma reduction. The NPs are stably and uniformly immobilized on the surface of MWNTs and the nanohybrid materials are applied to counter electrode (CE) of dye-sensitized solar cells (DSCs). The electrochemical properties of CEs are examined through cyclic voltammogram, electrochemical impedance spectroscopy, and Tafel measurements. As a result, both electrochemical catalytic activity and electrical conductivity are highest for PtAu/MWNT electrode. The DSC employing PtAu/MWNT CE exhibits power conversion efficiency of 7.9%. The efficiency is better than those of devices with MWNT (2.6%), AuNP/MWNT (2.7%) and PtNP/MWNT (7.5%) CEs.

  13. Photoamperometric flow injection analysis of glucose based on dehydrogenase modified quantum dots-carbon nanotube nanocomposite electrode.

    Science.gov (United States)

    Ertek, Bensu; Dilgin, Yusuf

    2016-12-01

    In this work, a core-shell quantum dot (QD, ZnS-CdS) was electrodeposited onto multiwalled carbon nanotube modified glassy carbon electrode (ZnS-CdS/MWCNT/GCE) and following glucose dehydrogenase (GDH) was immobilized onto QD modified electrode. The proposed electrode (GDH/ZnS-CdS/MWCNT/GCE) was effectively used for the photoelectrochemical biosensing of glucose in flow injection analysis (FIA) system using a home-made flow cell. Results from cyclic voltammetric and FI amperometric measurements have revealed that GDH/ZnS-CdS/MWCNT/GCE is capable of signaling photoelectrocatalytic activity toward NADH when the surface of enzyme modified electrode was irradiated with a light source (250W Halogen lamp). Thus, photoelectrochemical biosensing of glucose was monitored by recording current-time curve of enzymatically produced NADH at optimized conditions. The biosensor response was found linear over the range 0.010-2.0mM glucose with detection limits of 6.0 and 4.0μM for amperometric and photoamperometric methods, respectively. The relative standard deviations (n=5) for 0.5mM glucose were 5.8% and 3.8% for photoamperometric and amperometric results, respectively. The photoelectrochemical biosensor was successfully applied to the real samples. The results with this biosensor showed good selectivity, repeatability and sensitivity for monitoring glucose in amperometric and photoamperometric FIA studies. PMID:26944347

  14. Amperometric bienzyme glucose biosensor based on carbon nanotube modified electrode with electropolymerized poly(toluidine blue O) film

    Energy Technology Data Exchange (ETDEWEB)

    Wang Wenju [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong (Hong Kong); Wang Fang [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong (Hong Kong)] [Department of Chemistry, Wuhan University, Wuhan 430072 (China); Yao Yanli [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong (Hong Kong); Hu Shengshui [Department of Chemistry, Wuhan University, Wuhan 430072 (China); Shiu, Kwok-Keung, E-mail: kkshiu@hkbu.edu.h [Department of Chemistry, Hong Kong Baptist University, Kowloon Tong (Hong Kong)

    2010-09-30

    The amperometric bienzyme glucose biosensor utilizing horseradish peroxidase (HRP) and glucose oxidase (GOx) immobilized in poly(toluidine blue O) (PTBO) film was constructed on multi-walled carbon nanotube (MWNT) modified glassy carbon electrode. The HRP layer could be used to analyze hydrogen peroxide with toluidine blue O (TBO) mediators, while the bienzyme system (HRP + GOx) could be utilized for glucose determination. Glucose underwent biocatalytic oxidation by GOx in the presence of oxygen to yield H{sub 2}O{sub 2} which was further reduced by HRP at the MWNT-modified electrode with TBO mediators. In the absence of oxygen, glucose oxidation proceeded with electron transfer between GOx and the electrode mediated by TBO moieties without H{sub 2}O{sub 2} production. The bienzyme electrode offered high sensitivity for amperometric determination of glucose at low potential, displaying Michaelis-Menten kinetics. The bienzyme glucose biosensor displayed linear response from 0.1 to 1.2 mM with a sensitivity of 113 mA M{sup -1} cm{sup -2} at an applied potential of -0.10 V in air-saturated electrolytes.

  15. Voltammetric Determination of Homocysteine Using Multiwall Carbon Nanotube Paste Electrode in the Presence of Chlorpromazine as a Mediator

    Directory of Open Access Journals (Sweden)

    Fathali Gholami-Orimi

    2012-01-01

    Full Text Available We propose chlorpromazine (CHP as a new mediator for the rapid, sensitive, and highly selective voltammetric determination of homocysteine (Hcy using multiwall carbon nanotube paste electrode (MWCNTPE. The experimental results showed that the carbon nanotube paste electrode has a highly electrocatalytic activity for the oxidation of Hcy in the presence of CHP as a mediator. Cyclic voltammetry, double potential step chronoamperometry, and square wave voltammetry (SWV are used to investigate the suitability of CHP at the surface of MWCNTPE as a mediator for the electrocatalytic oxidation of Hcy in aqueous solutions. The kinetic parameters of the system, including electron transfer coefficient, and catalytic rate constant were also determined using the electrochemical approaches. In addition, SWV was used for quantitative analysis. SWV showed wide linear dynamic range (0.1–210.0 μM Hcy with a detection limit of 0.08 μM Hcy. Finally, this method was also examined as a selective, simple, and precise electrochemical sensor for the determination of Hcy in real samples.

  16. Modification of glassy carbon electrode with a bilayer of multiwalled carbon nanotube/tiron-doped polypyrrole: Application to sensitive voltammetric determination of acyclovir

    International Nuclear Information System (INIS)

    A novel voltammetric sensor based on glassy carbon electrode (GCE) modified with a thin film of multi-walled carbon nanotubes (MWCNTs) coated with an electropolymerized layer of tiron-doped polypyrrole was developed and the resulting electrode was applied for the determination of acyclovir (ACV). The surface morphology and property of the modified electrode were characterized by field emission scanning electron microscopy and electrochemical impedance spectroscopy techniques. The electrochemical performance of the modified electrode was investigated by means of linear sweep voltammetry (LSV). The effect of several experimental variables, such as pH of the supporting electrolyte, drop size of the cast MWCNTssuspension, number of electropolymerization cycles and accumulation time was optimized by monitoring the LSV response of the modified electrode toward ACV. The best response was observed at pH 7.0 after accumulation at open circuit for 160 s. Under the optimized conditions, a significant electrochemical improvement was observed toward the electrooxidation of ACV on the modified electrode surface relative to the bare GCE, resulting in a wide linear dynamic range (0.03–10.0 μM) and a low detection limit (10.0 nM) for ACV. Besides high sensitivity, the sensor represented high stability and good reproducibility for ACV analysis, and provided satisfactory results for the determination of this compound in pharmaceutical and clinical preparations. - Highlights: • A simple method was employed to construct a thin film modified electrode. • Tiron-doped polypyrrole was electropolymerized on MWCNT precast glassy carbon electrode. • Electrode surface characterization was performed by microscopic and spectroscopic techniques. • The modified electrode showed nano-molar detection limit for acyclovir. • The modified electrode was applied for the detection of ACV in pharmaceutical and clinical preparations

  17. Modification of glassy carbon electrode with a bilayer of multiwalled carbon nanotube/tiron-doped polypyrrole: Application to sensitive voltammetric determination of acyclovir

    Energy Technology Data Exchange (ETDEWEB)

    Shahrokhian, Saeed, E-mail: shahrokhian@sharif.edu [Department of Chemistry, Sharif University of Technology, Tehran 11155-3516 (Iran, Islamic Republic of); Institute for Nanoscience and Technology, Sharif University of Technology, Tehran (Iran, Islamic Republic of); Azimzadeh, Mahnaz [Department of Chemistry, Sharif University of Technology, Tehran 11155-3516 (Iran, Islamic Republic of); Amini, Mohammad K. [Department of Chemistry, Isfahan University, Isfahan (Iran, Islamic Republic of)

    2015-08-01

    A novel voltammetric sensor based on glassy carbon electrode (GCE) modified with a thin film of multi-walled carbon nanotubes (MWCNTs) coated with an electropolymerized layer of tiron-doped polypyrrole was developed and the resulting electrode was applied for the determination of acyclovir (ACV). The surface morphology and property of the modified electrode were characterized by field emission scanning electron microscopy and electrochemical impedance spectroscopy techniques. The electrochemical performance of the modified electrode was investigated by means of linear sweep voltammetry (LSV). The effect of several experimental variables, such as pH of the supporting electrolyte, drop size of the cast MWCNTssuspension, number of electropolymerization cycles and accumulation time was optimized by monitoring the LSV response of the modified electrode toward ACV. The best response was observed at pH 7.0 after accumulation at open circuit for 160 s. Under the optimized conditions, a significant electrochemical improvement was observed toward the electrooxidation of ACV on the modified electrode surface relative to the bare GCE, resulting in a wide linear dynamic range (0.03–10.0 μM) and a low detection limit (10.0 nM) for ACV. Besides high sensitivity, the sensor represented high stability and good reproducibility for ACV analysis, and provided satisfactory results for the determination of this compound in pharmaceutical and clinical preparations. - Highlights: • A simple method was employed to construct a thin film modified electrode. • Tiron-doped polypyrrole was electropolymerized on MWCNT precast glassy carbon electrode. • Electrode surface characterization was performed by microscopic and spectroscopic techniques. • The modified electrode showed nano-molar detection limit for acyclovir. • The modified electrode was applied for the detection of ACV in pharmaceutical and clinical preparations.

  18. Non-enzymatic sensing of hydrogen peroxide using a glassy carbon electrode modified with a nanocomposite made from carbon nanotubes and molybdenum disulfide

    International Nuclear Information System (INIS)

    We report on a non-enzymatic electrochemical sensing strategy for ultrasensitive detection of hydrogen peroxide (H2O2) at nanomolar levels. A glassy carbon electrode (GCE) was modified with a hybrid material consisting of multiwalled carbon nanotubes (CNT) and molybdenum disulfide (MoS2). Transmission electron microscopy and Raman spectroscopy were employed to characterize the hybrid nanostructures. GCEs modified with carbon nanotubes, or nanoscaled MoS2, or with the CNT-MoS2 hybrid were investigated with respect to sensing H2O2, and this revealed that the GCE modified with the CNT-MoS2 hybrid performed best and resulted in a limit of detection as low as 5.0 nM. A repeatability and intermediate precision of 9 % was accomplished. The method was applied to determine H2O2 in spiked sterilized milk and gave satisfactory results. (author)

  19. Carbon nanotubes and graphene modified screen-printed carbon electrodes as sensitive sensors for the determination of phytochelatins in plants using liquid chromatography with amperometric detection.

    Science.gov (United States)

    Dago, Àngela; Navarro, Javier; Ariño, Cristina; Díaz-Cruz, José Manuel; Esteban, Miquel

    2015-08-28

    Nanomaterials are of great interest for the development of electrochemical sensors. Multi-walled carbon nanotubes and graphene were used to modify the working electrode surface of different screen-printed carbon electrodes (SPCE) with the aim of improving the sensitivity of the SPCE and comparing it with the conventional glassy carbon electrode. To assay the usability of these sensors, a HPLC methodology with amperometric detection was developed to analyze several phytochelatins in plants of Hordeum vulgare and Glycine max treated with Hg(II) or Cd(II) giving detection limits in the low μmolL(-1) range. Phytochelatins are low molecular weight peptides with the general structure γ-(Glu-Cys)n-Gly (n=2-5) which are synthesized in plants in the presence of heavy metal ions. These compounds can chelate heavy metal ions by the formation of complexes which, are transported to the vacuoles, where the toxicity is not threatening. For this reason phytochelatins are essential in the detoxification of heavy metal ions in plants. The developed HPLC method uses a mobile phase of 1% of formic acid in water with KNO3 or NaCl (pH=2.00) and 1% of formic acid in acetonitrile. Electrochemical detection at different carbon-based electrodes was used. Among the sensors tested, the conventional glassy carbon electrode offers the best sensitivity although modification improves the sensitivity of the SPCE. Glutathione and several isoforms of phytochelatin two were found in plant extracts of both studied species. PMID:26212803

  20. Application of Multi-Walled Carbon Nanotubes Modified Glassy Carbon Electrode for Determination of Mefenamic Acid in Pharmaceutical Preparations and Biological Fluids

    International Nuclear Information System (INIS)

    A chemically modified electrode is constructed based on multi-walled carbon nanotube modified glassy carbon electrode (MWCNTs/GCE). It is demonstrated that this sensor could be used for determination of pharmaceutically important compound mefenamic acid (MEF). Differential pulse voltammetry (DPV) experiments of various concentration of MEF showed two linear dynamic ranges. The first linear dynamic range was from 2 micro M to 40 micro M, and the second linear dynamic range was between 50 micro M to 360 micro M. A detection limit of 0.21 micro M (S/N = 3) was obtained. Under optimal conditions the modified electrode exhibited high sensitivity and stability for determination of MEF, making it a suitable sensor for the submicromolar detection of MEF in solutions. The analytical performance of this sensor has been evaluated for the detection of MEF in human serum, human urine and a pharmaceutical preparation with satisfactory results. (author)

  1. A Voltammetric Biosensor Based on Glassy Carbon Electrodes Modified with Single-Walled Carbon Nanotubes/Hemoglobin for Detection of Acrylamide in Water Extracts from Potato Crisps

    Directory of Open Access Journals (Sweden)

    Hanna Radecka

    2008-09-01

    Full Text Available The presence of toxic acrylamide in a wide range of food products such as potato crisps, French fries or bread has been confirmed by Swedish scientists from Stockholm University. The neurotoxicity, possible carcinogenicity of this compound and its metabolites compels us to control them by quantitative and qualitative assays. Acrylamide forms adduct with hemoglobin (Hb as a result of the reaction the -NH2 group of the Nterminal valine with acrylamide. In this work we present the use of glassy carbon electrodes coated with single-walled carbon nanotubes (SWCNTs and Hb for voltammetric detection of acrylamide in water solutions. The electrodes presented a very low detection limit (1.0×10-9 M. The validation made in the matrix obtained by water extraction of potato crisps showed that the electrodes presented are suitable for the direct determination of acrylamide in food samples.

  2. Enhanced direct electron transfer between laccase and hierarchical carbon microfibers/carbon nanotubes composite electrodes. Comparison of three enzyme immobilization methods

    International Nuclear Information System (INIS)

    Three immobilization protocols were investigated with respect to direct electron transfer between hierarchical carbon microfibers/carbon nanotubes composite material on graphite rod electrodes and Trametes hirsuta laccase. Immobilization was done by covalent binding of laccase to aminophenyl-modified electrodes via amide-bond formation with carboxylic acid residues or imino-bond formation with aldehyde groups introduced by oxidation of sugar residues of the enzyme's glycosylation shell. Moreover, immobilization was achieved by adsorbing laccase to electrodes hydrophilized with pyrene-hexanoic acid. High current densities for biocatalytic oxygen reduction were obtained for all immobilization strategies. The formation of the imino bonds let to the binding of laccase in close to 100% direct electron transfer configuration and consequently to the highest oxygen reduction currents.

  3. Highly catalytic carbon nanotube counter electrode on plastic for dye solar cells utilizing cobalt-based redox mediator

    International Nuclear Information System (INIS)

    A flexible, slightly transparent and metal-free random network of single-walled carbon nanotubes (SWCNTs) on plain polyethylene terephthalate (PET) plastic substrate outperformed platinum on conductive glass and on plastic as the counter electrode (CE) of a dye solar cell employing a Co(II/III)tris(2,2′-bipyridyl) complex redox mediator in 3-methoxypropionitrile solvent. The CE charge-transfer resistance of the SWCNT film was 0.60 Ω cm2, 4.0 Ω cm2 for sputtered platinum on indium tin oxide-PET substrate and 1.7 Ω cm2 for thermally deposited Pt on fluorine-doped tin oxide glass, respectively. The solar cell efficiencies were in the same range, thus proving that an entirely carbon-based SWCNT film on plastic is as good CE candidate for the Co electrolyte

  4. Designer electrode interfaces simultaneously comprising three different metal nanoparticle (Au, Ag, Pd)/carbon microsphere/carbon nanotube composites: progress towards combinatorial electrochemistry.

    Science.gov (United States)

    Dai, Xuan; Wildgoose, Gregory G; Compton, Richard G

    2006-11-01

    In this report gold, silver and palladium metal nanoparticles are separately supported on glassy carbon microspheres (GCM) using bulk electroless deposition techniques to produce three different materials labelled as GCM-Au, GCM-Ag and GCM-Pd respectively. These three materials are then combined together into a composite film on a glassy carbon (GC) electrode surface using multiwalled carbon nanotubes (MWCNTs). The MWCNTs serve to not only mechanically support this composite film as a "binder" but they also help to "wire up" each modified GCM to the underlying substrate. The intelligently designed structure of this electrode interface allows this single modified electrode to simultaneously behave as if it were a macrodisc electrode constructed of gold, silver or palladium, whilst using only a fraction of the equivalent amount of these precious metals. Furthermore this unique structure allows the possibility of combinatorial electrochemistry to be realised using a relatively facile electrode construction which avoids the problems of alloy formation, co-deposition and the formation of bimetallic species. For instance a mixture of several different analytes, which can each only be detected on a different specific substrate, can simultaneously be determined using one electrode in a single voltammetric experiment! Alternatively a substrate could undergo electrocatalytic reactions on one substrate, whilst the products, and hence the progress of this reaction, can be studied at a different substrate simultaneously at the same electrode surface. Proof-of-concept examples are presented herein and the designer electrode interface is shown to produce analytical responses to model target analytes such as hydrazine, bromide and thallium(I) ions that are comparable, if not better, than those obtained at metal macrodisc electrodes and even at other state-of-the-art nanoparticle modified electrodes. PMID:17066193

  5. PEG-assisted Synthesis of Homogeneous Carbon Nanotubes-MoS2-Carbon as a Counter Electrode for Dye-sensitized Solar Cells

    International Nuclear Information System (INIS)

    Graphical abstract: We developed a polyethylene glycol-assisted strategy to improve the coating of ultra-thin MoS2 on carbon nanotubes (CNTs). The composite was used as counter electrodes (CEs) for dye-sensitized solar cells to give a higher photo-to-electron efficiency than that of Pt CEs. - Highlights: • A polyethylene glycol-assisted strategy was developed. • The homogeneous composite of CNTs-MoS2-carbon was prepared. • The composite was used as counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). • The CNTs-MoS2-carbon CEs possess low Rct of 1.73 Ω cm2. • DSSCs based on CNTs-MoS2-carbon CEs achieve a power conversion efficiency of 7.23%. - Abstract: Carbon nanotubes-MoS2-carbon (CNTs-MoS2-carbon) was synthesized via a method of wet impregnation and calcination with the assistance of surface-active polyethylene glycol 400 (PEG400). Characterizations of TEM, Raman spectra, XRD, XPS, BET and TG-DSC revealed that CNTs were homogenously coated with ultra-thin layers of MoS2. It was demonstrated that the unique structure is attributed to the wetting and emulsification capacity of PEG400. The CNTs-MoS2-carbon was used as counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). Analyses of electrochemistry indicate that the CEs modified by CNTs-MoS2-carbon have high activity and stability in the electro-reduction from I3− to I− due to the low charge transfer resistance. DSSCs based on CNTs-MoS2-carbon CEs were demonstrated to have a power conversion efficiency of 7.23%, which is higher than Pt CEs (6.19%)

  6. A novel non-enzymatic hydrogen peroxide sensor based on single walled carbon nanotubes-manganese complex modified glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Salimi, Abdollah, E-mail: absalimi@uok.ac.i [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Research Center for Nanotechnology, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Mahdioun, Monierosadat; Noorbakhsh, Abdollah [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Abdolmaleki, Amir [Department of Chemistry, Isfahan University of Technology, Isfahan, 84156/83111 (Iran, Islamic Republic of); Ghavami, Raoof [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of)

    2011-03-30

    A simple procedure was developed to prepare a glassy carbon (GC) electrode modified with single wall carbon nanotubes (SWCNTs) and phenazine derivative of Mn-complex. With immersing the GC/CNTs modified electrode into Mn-complex solution for a short period of time 20-100 s, a stable thin layer of the complex was immobilized onto electrode surface. Modified electrode showed a well defined redox couples at wide pH range (1-12). The surface coverages and heterogeneous electron transfer rate constants (k{sub s}) of immobilized Mn-complex were approximately 1.58 x 10{sup -10} mole cm{sup -2} and 48.84 s{sup -1}. The modified electrode showed excellent electrocatalytic activity toward H{sub 2}O{sub 2} reduction. Detection limit, sensitivity, linear concentration range and k{sub cat} for H{sub 2}O{sub 2} were, 0.2 {mu}M and 692 nA {mu}M{sup -1} cm{sup -2}, 1 {mu}M to 1.5 mM and 7.96({+-}0.2) x 10{sup 3} M{sup -1} s{sup -1}, respectively. Compared to other modified electrodes, this electrode has many advantageous such as remarkable catalytic activity, good reproducibility, simple preparation procedure and long term stability.

  7. Determination of Phenol and Chlorophenols at Single-Wall Carbon Nanotubes/Poly(3,4-ethylenedioxythiophene) Modified Glassy Carbon Electrode Using Flow Injection Amperometry

    OpenAIRE

    Negussie Negash; Hailemichael Alemu; Merid Tessema

    2014-01-01

    Phenol and chlorophenols were investigated using single-wall carbon nanotubes (SWCNT) and poly(3,4-ethylenedioxythiophene) (PEDOT) composite modified glassy carbon electrode (SWCNT/PEDOT/GCE) as a detector in flow injection system. Optimization of experimental variables such as the detection potential, flow rate, and pH of the carrier solution (0.1 M sodium acetate) for the determination of phenol (P), 4-chlorophenol (CP), 2,4-dichlorophenol (DCP), 2,4,6-trichlorophenol (TCP), and pentachloro...

  8. Microbial biofuel cell operating effectively through carbon nanotube blended with gold–titania nanocomposites modified electrode

    International Nuclear Information System (INIS)

    In this study, we have explored the possibility to fabricate microbial biofuel cell operating with carbon nanotube–gold–titania nanocomposites (CNT/Au/TiO2) as anode modifier. The results demonstrate that the CNT/Au/TiO2 electrode could be utilized as a new and effective microbial fuel cell (MFC) anode, which integrate the advantages of relevant nanocomposites such as high conductivity, high specific surface area, and easy adsorption of the microorganism. It is evident that the three-dimensional network nanostructures of CNT/Au/TiO2 are propitious to improve the relevant anode surface area and thus the adsorption of the microorganism, which can efficiently promote the electronic transfer rate between the probe and electrode. Meanwhile, it is noted that open circuit voltage of the CNT/Au/TiO2 nanocomposites modified carbon paper anode increased to 0.77 V, which is more than twice that of the open circuit voltage obtained with bare carbon paper anode (0.36 V). And the MFC equipped with CNT/Au/TiO2 nanocomposites modified carbon paper anode delivers a maximum power density of 2.4 mW m−2, which is three times larger than that obtained from the MFC with bare carbon paper. This observation illustrates that the CNT/Au/TiO2 nanocomposites modified electrode could obviously increase the relevant electron transfer rate and promote the electron exchange at electrode surface, which could readily provide enhanced stability and relatively long life-span to facilitate the high electricity production efficiency, suggesting its promising prospect application in MFCs

  9. A novel non-enzyme hydrogen peroxide sensor based on an electrode modified with carbon nanotube-wired CuO nanoflowers

    International Nuclear Information System (INIS)

    We have prepared a novel sensor for hydrogen peroxide that is based on a glassy carbon electrode modified with a film containing multi-walled carbon nanotubes wired to CuO nanoflowers. The nanoflowers were characterized by X-ray powder diffraction, and the electrode was characterized by cyclic voltammetry (CV) and scanning electron microscopy. The response of the modified electrode towards hydrogen peroxide was investigated by CV and chronoamperometry and showed it to exhibit high electrocatalytic activity, with a linear range from 0. 5 μM to 82 μM and a detection limit of 0. 16 μM. The sensor also displays excellent selectivity and stability. (author)

  10. Detection of Carbofuran with Immobilized Acetylcholinesterase Based on Carbon Nanotubes-Chitosan Modified Electrode

    OpenAIRE

    Shuping Zhang; Shaoyang Li; Jie Ma; Fei Xiong; Song Qu

    2013-01-01

    A sensitive and stable enzyme biosensor based on efficient immobilization of acetylcholinesterase (AChE) to MWNTs-modified glassy carbon electrode (GCE) with chitosan (CS) by layer-by-layer (LBL) technique for rapid determination of carbofuran has been devised. According to the inhibitory effect of carbamate pesticide on the enzymatic activity of AChE, we use carbofuran as a model pesticide. The inhibitory effect of carbofuran on the biosensor was proportional to concentration of carbofuran i...

  11. Electrosorptive desalination by carbon nanotubes and nanofibres electrodes and ion-exchange membranes.

    Science.gov (United States)

    Li, Haibo; Gao, Yang; Pan, Likun; Zhang, Yanping; Chen, Yiwei; Sun, Zhuo

    2008-12-01

    A novel membrane capacitive deionization (MCDI) device, integrating both the advantages of carbon nanotubes and carbon nanofibers (CNTs-CNFs) composite film and ion-exchange membrane, was proposed with high removal efficiency, low energy consumption and low cost. The CNTs-CNFs film was synthesized by low pressure and low temperature thermal chemical vapor deposition. Several experiments were conducted to compare desalination performance of MCDI with capacitive deionization (CDI), showing that salt removal of the MCDI system was 49.2% higher than that of the CDI system. The electrosorption isotherms of MCDI and CDI show both of them follow Langmuir adsorption, indicating no change in adsorption behavior when ion-exchange membranes are introduced into CDI system. The better desalination performance of MCDI than that of CDI is due to the minimized ion desorption during electrosorption. PMID:18929385

  12. Sensitive voltammetric determination of chloramphenicol by using single-wall carbon nanotube-gold nanoparticle-ionic liquid composite film modified glassy carbon electrodes

    International Nuclear Information System (INIS)

    A novel composite film modified glassy carbon electrode has been fabricated and characterized by scanning electron microscope (SEM) and voltammetry. The composite film comprises of single-wall carbon nanotube (SWNT), gold nanoparticle (GNP) and ionic liquid (i.e. 1-octyl-3-methylimidazolium hexafluorophosphate), thus has the characteristics of them. The resulting electrode shows good stability, high accumulation efficiency and strong promotion to electron transfer. On it, chloramphenicol can produce a sensitive cathodic peak at -0.66 V (versus SCE) in pH 7.0 phosphate buffer solutions. Parameters influencing the voltammetric response of chloramphenicol are optimized, which include the composition of the film and the operation conditions. Under the optimized conditions, the peak current is linear to chloramphenicol concentration in the range of 1.0 x 10-8-6.0 x 10-6 M, and the detection limit is estimated to be 5.0 x 10-9 M after an accumulation for 150 s on open circuit. The electrode is applied to the determination of chloramphenicol in milk samples, and the recoveries for the standards added are 97.0% and 100.3%. In addition, the electrochemical reaction of chloramphenicol and the effect of single-wall carbon nanotube, gold nanoparticle and ionic liquid are discussed

  13. Layer-by-layer self-assembling copper tetrasulfonated phthalocyanine on carbon nanotube modified glassy carbon electrode for electro-oxidation of 2-mercaptoethanol

    Energy Technology Data Exchange (ETDEWEB)

    Shaik, Mahabul, E-mail: mshaik86@gmail.com; Rao, V.K.; Gupta, Manish; Pandey, P.

    2012-12-30

    This paper describes the electrocatalytic activity of layer-by-layer self-assembled copper tetrasulfonated phthalocyanine (CuPcTS) on carbon nanotube (CNT)-modified glassy carbon (GC) electrode. CuPcTS is immobilized on the negatively charged CNT surface by alternatively assembling a cationic poly(diallyldimethylammonium chloride) (PDDA) layer and a CuPcTS layer. UV-vis absorption spectra and electrochemical measurements suggested the successive linear depositions of the bilayers of CuPcTs and PDDA on CNT. The surface morphology was observed using scanning electron microscopy. The viability of this CuPcTS/PDDA/CNT modified GC electrode as a redox mediator for the anodic oxidation and sensitive amperometric determination of 2-mercaptoethanol (2-ME) in alkaline conditions is described. The effect of number of bilayers of CuPcTS/PDDA and pH on electrochemical oxidation of 2-ME was studied. The proposed electrochemical sensor displayed excellent characteristics towards the determination of 2-ME in 0.1 M NaOH; such as low overpotentials (- 0.15 V vs Ag/AgCl), linear concentration range of 3 Multiplication-Sign 10{sup -5} M to 6 Multiplication-Sign 10{sup -3} M, and with a detection limit of 2.5 Multiplication-Sign 10{sup -5} M using simple amperometry. - Highlights: Black-Right-Pointing-Pointer Carbon nanotubes (CNT) were drop-dried on glassy carbon electrode (GCE). Black-Right-Pointing-Pointer Copper tetrasulfonated phthalocyanine (CuPcTS) was deposited on CNT/GCE. Black-Right-Pointing-Pointer Layer-by-layer self-assembling method is used for depositing CuPcTS. Black-Right-Pointing-Pointer Electrocatalytic oxidation of 2-mercaptoethanol (ME) was studied at this electrode Black-Right-Pointing-Pointer The detection limit of ME at modified electrode was 25 {mu}M by amperometry.

  14. Fine structure and related properties of the assembleable carbon nanotubes based electrode for new family of biosensors with chooseable selectivity.

    Science.gov (United States)

    Razumiene, Julija; Gureviciene, Vidute; Voitechovic, Edita; Barkauskas, Jurgis; Bukauskas, Virginijus; Setkus, Arūnas

    2011-10-01

    Surfaces of constituent parts of biosensors based on single wall carbon nanotube layer were investigated and compare for properly functioning and faulty biosensors. Though the original technology is acceptable for changing of the selectivity, only glucose sensitive biosensors are investigated. Based on the results of the study, a correlation between the features of the nanoscale structures and parameters of amperiometric biosensors for assemblage of which an innovative approach is described. Original template of the electrodes has been prepared on a base of single wall carbon nanotube layer deposited on the supporting polycarbonate membrane. Original immobilisation of enzymes within special membrane allows functional modification of biosensors being accomplished by simple replacement of the enzymatic membrane. The original technology leads to a novel family of biosensors acceptable for detection of wide range of carbohydrates. The morphology and the local electric properties of the constituent parts of the biosensors are characterized by scanning probe microscopy. The sensitivity, selectivity and stability are described for typical types of the biosensors. PMID:22400293

  15. Voltammetric and amperometric determination of hydrogen peroxide using a carbon-ceramic electrode modified with a nanohybrid composite made from single-walled carbon nanotubes and silver nanoparticles

    International Nuclear Information System (INIS)

    A nanohybrid composite material was prepared from single-walled carbon nanotubes and silver nanoparticles, and used to fabricate a modified carbon-ceramic electrode. The preparation of the composite is facile and efficient. The nanohybrid composite deposited on the carbon-ceramic electrode was characterized by X-ray diffraction and cyclic voltammetry. The new electrode displays favorable electrocatalytic ability towards hydrogen peroxide (HO2) and can be used to electrocatalytically reduce this species. Under the optimum conditions, the current measured during hydrodynamic amperometry is linearly related to the concentration of H2O2 over the concentration range from 0.01 to 8 mM, with a detection limit of 2 x 10-7 M at a signal-to-noise ratio of 3 and sensitivity of 3.23 μA/mM. The electrode exhibits good reproducibility, long-term stability and negligible interference by dopamine, uric acid, and other important biological compounds. The electrode was successfully applied to the determination of H2O2 in honey samples, and the recovery was 101.2%. (author)

  16. Electrochemical performance of solid-state lithium-air batteries using carbon nanotube catalyst in the air electrode

    Energy Technology Data Exchange (ETDEWEB)

    Kitaura, Hirokazu; Zhou, Haoshen [Energy Technology Research Institute, National Institute of Advanced Industrial Science and Technology, Umezono, Tsukuba (Japan)

    2012-07-15

    Solid-state lithium-air cells using lithium anode, a polymer electrolyte, Li{sub 1+x+y}Al{sub x}(Ti, Ge){sub 2-x}Si{sub y}P{sub 3-y}O{sub 12} inorganic solid electrolyte, and an air electrode composed of carbon nanotubes and an inorganic solid electrolyte are constructed and their electrochemical properties investigated. The cells show a reversible capacity of about 400 mA h g{sup -1} during the first few cycles. The rate performance and impedance measurements are also examined. The large cell resistance, which mainly comes from the interfacial resistance between Li and the polymer electrolyte, limits the rate performance. The results indicate that such all-solid-state lithium-air batteries without polymer electrolytes have good potential for development. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. Bifacial dye-sensitized solar cells from covalent-bonded polyaniline-multiwalled carbon nanotube complex counter electrodes

    Science.gov (United States)

    Zhang, Huihui; He, Benlin; Tang, Qunwei; Yu, Liangmin

    2015-02-01

    Exploration of cost-effective counter electrodes (CEs) and enhancement of power conversion efficiency have been two persistent objectives for dye-sensitized solar cells (DSSCs). In the current work, polyaniline-multiwalled carbon nanotube (PANi-MWCNT) complexes are synthesized by a reflux method and employed as CE materials for bifacial DSSCs. Owing to the high optical transparency of PANi-MWCNT complex CE, the incident light from rear side can compensate for the incident light from TiO2 anode. The charge-transfer ability and electrochemical behaviors demonstrate the potential utilization of PANi-MWCNT complex CEs in robust bifacial DSSCs. The electrochemical properties as well as photovoltaic performances are optimized by adjusting MWCNT dosages. A maximum power conversion efficiency of 9.24% is recorded from the bifacial DSSC employing PANi-8 wt‰ MWCNT complex CE for both irradiation, which is better than 8.08% from pure PANi CE.

  18. Development of 3D carbon nanotube interdigitated finger electrodes on polymer substrate for flexible capacitive sensor application

    International Nuclear Information System (INIS)

    This study reports a novel approach to the implementation of 3D carbon nanotube (CNT) interdigitated finger electrodes on flexible polymer, and the detection of strain, bending curvature, tactile force and proximity distance are demonstrated. The merits of the presented CNT-based flexible sensor are as follows: (1) the silicon substrate is patterned to enable the formation of 3D vertically aligned CNTs on the substrate surface; (2) polymer molding on the silicon substrate with 3D CNTs is further employed to transfer the 3D CNTs to the flexible polymer substrate; (3) the CNT–polymer composite (∼70 μm in height) is employed to form interdigitated finger electrodes to increase the sensing area and initial capacitance; (4) other structures such as electrical routings, resistors and mechanical supporters are also available using the CNT–polymer composite. The preliminary fabrication results demonstrate a flexible capacitive sensor with 50 μm high CNT interdigitated electrodes on a poly-dimethylsiloxane substrate. The tests show that the typical capacitance change is several dozens of fF and the gauge factor is in the range of 3.44–4.88 for strain and bending curvature measurement; the sensitivity of the tactile sensor is 1.11% N−1; a proximity distance near 2 mm away from the sensor can be detected. (paper)

  19. Role of iron oxide impurities in electrocatalysis by multiwall carbon nanotubes: An investigation using a novel magnetically modified ITO electrodes

    Indian Academy of Sciences (India)

    Kanchan M Samant; Vrushali S Joshi; Kashinath R Patil; Santosh K Haram

    2014-04-01

    The role of iron oxide impurities in the electrocatalytic properties of multiwall carbon nanotubes (MWCNTs) prepared by catalytic chemical vapour decomposition method (CCVD) is studied in detail. A novel magnetically modified electrodes have been developed by which MWCNTs were immobilized on indium-tin oxide (ITO) electrodes, without any chemical binders. The electro-catalytic oxidation of dopamine, and reduction of hydrogen peroxide have been studied by cyclic voltammetry on magnetically modified electrodes with (i) MWCNTs with occluded iron oxide impurities (Fe-MWCNTs), (ii) MWCNTs grown on iron oxide nanoparticle particulate films (Io-MWCNTs) and (iii) pristine iron oxide nanoparticle particulate film (Io-NPs). A shift towards less positive potentials for the oxidation of dopamine was observed which is in the order of Fe-MWCNTs < Io-MWCNTs < Io-NPs. Similarly, trend towards less negative potentials for the reduction of hydrogen peroxide was observed. Thus, the electrocatalytic activities displayed by MWCNTs have been attributed to the iron oxide impurities associated with it. The systematic variation was related to the nature of interaction of iron oxide nanoparticles with MWCNT surface.

  20. Enzyme-free sensing of glucose on a copper electrode modified with nickel nanoparticles and multiwalled carbon nanotubes

    International Nuclear Information System (INIS)

    We describe a new electrochemical platform for direct sensing of glucose. The electrode was prepared by controlled electrodeposition of nickel nanoparticles onto carbon nanotubes on a copper electrode. The sensor was optimized by investigating the effects of the concentration of nickel precursor, electrolysis time and acidity of the medium. The nanocomposite was characterized by scanning electron microscopy and energy dispersive spectroscopy. Cyclic voltammetry of glucose in 0.1 M NaOH solution gives a well-defined anodic wave with a peak potential at 0.53 V (vs. Ag/AgCl) that indicates the direct electrooxidation of glucose at the nanomaterial. The electrode responds to glucose over a wide linear range (from 2 μM to 10 mM), with high sensitivity (3.8 mA∙mM−1∙cm−2) and a low detection limit (0.7 μM). The sensor was applied to the determination of glucose in blood samples, and the results were in good agreement with data obtained by a commercially available glucometer. The method holds promise due to the ease of sensor fabrication and its robust performance and longevity. (author)

  1. Mild in situ growth of platinum nanoparticles on multiwalled carbon nanotube-poly (vinyl alcohol) hydrogel electrode for glucose electrochemical oxidation

    International Nuclear Information System (INIS)

    This investigation describes an effective strategy to fabricate an electrochemically active hybrid hydrogel made from platinum nanoparticles that are highly dense, uniformly dispersed, and tightly embedded throughout the conducting hydrogel network for the electrochemical oxidation of glucose. A suspension of multiwalled carbon nanotubes and polyvinyl alcohol aqueous was coated on glassy carbon electrode by electrophoretic deposition and then physically crosslinked to form a three-dimensional porous conductive hydrogel network by a process of freezing and thawing. The network offered 3D interconnected mass-transport channels (around 200 nm) and confined nanotemplates for in situ growth of uniform platinum nanoparticles via the moderate reduction agent, ascorbic acid. The resulting hybrid hydrogel electrode membrane demonstrates an effective method for loading platinum nanoparticles on multiwalled carbon nanotubes by the electrostatic adsorption between multiwalled carbon nanotubes and platinum ions within porous hydrogel network. The average diameter of platinum nanoparticles is 37 ± 14 nm, which is less than the particle size by only using the moderate reduction agent. The hybrid hydrogel electrode membrane-coated glassy carbon electrode showed excellent electrocatalytic activity and good long-term stability toward glucose electrochemical oxidation. The glucose oxidation current exhibited a linear relationship with the concentration of glucose in the presence of chloride ions, promising for potential applications of implantable biofuel cells, biosensors, and electronic devices

  2. Mild in situ growth of platinum nanoparticles on multiwalled carbon nanotube-poly (vinyl alcohol) hydrogel electrode for glucose electrochemical oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shumin; Zheng, Yudong, E-mail: zhengyudong@mater.ustb.edu.cn; Qiao, Kun [University of Science and Technology Beijing, School of Material Science and Engineering (China); Su, Lei [University of Science and Technology Beijing, School of Chemistry and Biological Engineering (China); Sanghera, Amendeep; Song, Wenhui [University College London, UCL Centre for Nanotechnology & Regenerative Medicine, Division of Surgery and Interventional Science (United Kingdom); Yue, Lina; Sun, Yi [University of Science and Technology Beijing, School of Material Science and Engineering (China)

    2015-12-15

    This investigation describes an effective strategy to fabricate an electrochemically active hybrid hydrogel made from platinum nanoparticles that are highly dense, uniformly dispersed, and tightly embedded throughout the conducting hydrogel network for the electrochemical oxidation of glucose. A suspension of multiwalled carbon nanotubes and polyvinyl alcohol aqueous was coated on glassy carbon electrode by electrophoretic deposition and then physically crosslinked to form a three-dimensional porous conductive hydrogel network by a process of freezing and thawing. The network offered 3D interconnected mass-transport channels (around 200 nm) and confined nanotemplates for in situ growth of uniform platinum nanoparticles via the moderate reduction agent, ascorbic acid. The resulting hybrid hydrogel electrode membrane demonstrates an effective method for loading platinum nanoparticles on multiwalled carbon nanotubes by the electrostatic adsorption between multiwalled carbon nanotubes and platinum ions within porous hydrogel network. The average diameter of platinum nanoparticles is 37 ± 14 nm, which is less than the particle size by only using the moderate reduction agent. The hybrid hydrogel electrode membrane-coated glassy carbon electrode showed excellent electrocatalytic activity and good long-term stability toward glucose electrochemical oxidation. The glucose oxidation current exhibited a linear relationship with the concentration of glucose in the presence of chloride ions, promising for potential applications of implantable biofuel cells, biosensors, and electronic devices.

  3. A novel composite electrode based on tungsten oxide nanoparticles and carbon nanotubes for the electrochemical determination of paracetamol

    International Nuclear Information System (INIS)

    An electrochemical sensor was prepared by the modification of a glassy carbon electrode (GCE) with a composite of nanoparticles of tungsten oxide (WO3) and carbon nanotubes (CNTs) for the quantification of paracetamol (PR). Energy dispersive X-ray analysis (EDX) and scanning electron microscopy (SEM) were performed for the characterization of the nanocomposite layer. Compared with a bare GCE and a GCE modified with CNTs, the proposed electrode (WO3NPs/CNTs/GCE) exhibited a well-defined redox couple for PR and a marked enhancement of the current response. The experimental results also showed that ascorbic acid (AA) did not interfere with the selective determination of PR. The proposed electrode was used for the determination of PR in 0.1 M phosphate buffer solution (PBS) at pH 7.0 using square wave voltammetry (SWV). The peak current increased linearly with the concentration of PR in the range of 1.0 × 10−9–2.0 × 10−7 M. The detection limit (LOD) was 5.54 × 10−11 M (based on 3 Sb/m). The proposed voltammetric sensor provided long-time stability, improved voltammetric behavior and good reproducibility for PR. The selective, accurate and precise determination of PR makes the proposed electrode of great interest for monitoring its therapeutic use. - Highlights: • A voltammetric nanosensor was prepared using nanoparticles of WO3 and CNTs. • A selective quantification of paracetamol was carried out in the presence of AA. • A linear plot was obtained for current responses versus concentrations over the range from 1.0 × 10−9 to 2.0 × 10−7 M. • A detection limit of 554 pM was obtained for paracetamol using the proposed nanosensor. • An accurate quantification makes the proposed nanosensor of great interest for public health

  4. A novel composite electrode based on tungsten oxide nanoparticles and carbon nanotubes for the electrochemical determination of paracetamol

    Energy Technology Data Exchange (ETDEWEB)

    Baytak, Aysegul Kutluay; Duzmen, Sehriban; Teker, Tugce; Aslanoglu, Mehmet, E-mail: maslanoglu@harran.edu.tr

    2015-12-01

    An electrochemical sensor was prepared by the modification of a glassy carbon electrode (GCE) with a composite of nanoparticles of tungsten oxide (WO{sub 3}) and carbon nanotubes (CNTs) for the quantification of paracetamol (PR). Energy dispersive X-ray analysis (EDX) and scanning electron microscopy (SEM) were performed for the characterization of the nanocomposite layer. Compared with a bare GCE and a GCE modified with CNTs, the proposed electrode (WO{sub 3}NPs/CNTs/GCE) exhibited a well-defined redox couple for PR and a marked enhancement of the current response. The experimental results also showed that ascorbic acid (AA) did not interfere with the selective determination of PR. The proposed electrode was used for the determination of PR in 0.1 M phosphate buffer solution (PBS) at pH 7.0 using square wave voltammetry (SWV). The peak current increased linearly with the concentration of PR in the range of 1.0 × 10{sup −9}–2.0 × 10{sup −7} M. The detection limit (LOD) was 5.54 × 10{sup −11} M (based on 3 S{sub b}/m). The proposed voltammetric sensor provided long-time stability, improved voltammetric behavior and good reproducibility for PR. The selective, accurate and precise determination of PR makes the proposed electrode of great interest for monitoring its therapeutic use. - Highlights: • A voltammetric nanosensor was prepared using nanoparticles of WO{sub 3} and CNTs. • A selective quantification of paracetamol was carried out in the presence of AA. • A linear plot was obtained for current responses versus concentrations over the range from 1.0 × 10{sup −9} to 2.0 × 10{sup −7} M. • A detection limit of 554 pM was obtained for paracetamol using the proposed nanosensor. • An accurate quantification makes the proposed nanosensor of great interest for public health.

  5. Carbon nanotube nanoelectrode arrays

    Science.gov (United States)

    Ren, Zhifeng; Lin, Yuehe; Yantasee, Wassana; Liu, Guodong; Lu, Fang; Tu, Yi

    2008-11-18

    The present invention relates to microelectode arrays (MEAs), and more particularly to carbon nanotube nanoelectrode arrays (CNT-NEAs) for chemical and biological sensing, and methods of use. A nanoelectrode array includes a carbon nanotube material comprising an array of substantially linear carbon nanotubes each having a proximal end and a distal end, the proximal end of the carbon nanotubes are attached to a catalyst substrate material so as to form the array with a pre-determined site density, wherein the carbon nanotubes are aligned with respect to one another within the array; an electrically insulating layer on the surface of the carbon nanotube material, whereby the distal end of the carbon nanotubes extend beyond the electrically insulating layer; a second adhesive electrically insulating layer on the surface of the electrically insulating layer, whereby the distal end of the carbon nanotubes extend beyond the second adhesive electrically insulating layer; and a metal wire attached to the catalyst substrate material.

  6. Enzyme entrapment by β-cyclodextrin electropolymerization onto a carbon nanotubes-modified screen-printed electrode.

    Science.gov (United States)

    Alarcón-Ángeles, G; Guix, M; Silva, W C; Ramírez-Silva, M T; Palomar-Pardavé, M; Romero-Romo, M; Merkoçi, A

    2010-12-15

    A novel enzyme entrapment approach based on an electropolymerization process utilizing multi-walled carbon nanotubes (MWCNT), β-cyclodextrin (β-CD) and glucose oxidase (GOx) is shown. Dopamine (DA) quantification is presented using a screen-printed electrode modified by electropolymerization of cyclodextrin with glucose oxidase, SPE/MWCNT/β-CD-GOx. In order to show the relevance of the enzyme entrapment strategy controlled by electropolymerization to develop a specific and efficient biosensor, the various parts composing the electrode: SPE, SPE/β-CD, SPE/GOx, SPE/β-CD/GOx, SPE/MWCNT/β-CD, SPE/MWCNT/GOx and SPE/MWCNT/β-CD/GOx were tested separately. It was shown that although DA determination can be achieved with all of them, the electrodes modified with MWCNT presented better analytical features that those built without MWCNT, the best being the one including all components. This biosensor displayed good reproducibility, repeatability, and prolonged life-time under cold storage conditions. Its DA limit of detection (LOD) was 0.48±0.02 μA in a linear range of 10-50 μM with a sensitivity of 0.0302±0.0003 μA μM(-1) that makes it comparable or even better than many other electrodes reported in the literature. Moreover, it was also shown that using this electrode, DA quantification can be done in the presence of interfering agents such as ascorbic and uric acid. These findings demonstrate that the approach employed is feasible for enzyme entrapment and may find applications in other biosensing systems, where better sensitivity, stability and fast response are required. PMID:20863684

  7. Hydrothermal synthesis of carbon nanotube/cubic Fe3O4 nanocomposite for enhanced performance supercapacitor electrode material

    International Nuclear Information System (INIS)

    Graphical abstract: First, the acid treated CNTs were used as support substrate. Then cubic Fe3O4 nanoparticles directly anchored on the surfaces of CNTs as supercapacitor electrode material by an easy and cost effective hydrothermal method. Results showed that the composite has superior capacitive performance with a maximum specific capacitance of 119 F/g. -- Highlights: • The acid treated CNTs were used as conductive substrate materials. • Cubic Fe3O4 nanoparticles directly grew onto surfaces of CNTs preventing the agglomeration of Fe3O4. • The loose structure improves the contact between the electrode and the electrolyte. • Results showed that this composite has good electrochemical property. -- Abstract: Carbon nanotube/Fe3O4 (CNT/Fe3O4) nanocomposite with well-dispersed Fe3O4 nano-cubes inlaid on the surfaces of carbon nanotubes, was synthesized through an easy and efficient hydrothermal method. The electrochemical behaviors of the nanocomposite were analyzed by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronopotentiometry in 6 M KOH electrolyte. Results demonstrated that CNT as the supporting material could significantly improve the supercapacitor (SC) performance of the CNT/Fe3O4 composite. Comparing with pure Fe3O4, the resulting composite exhibited improved specific capacitances of 117.2 F/g at 10 mA/cm2 (3 times than that of pure Fe3O4), excellent cyclic stability and a maximum energy density of 16.2 Wh/kg. The much improved electrochemical performances could be attributed to the good conductivity of CNTs as well as the anchored Fe3O4 particles on the CNTs

  8. Vanadium oxide–carbon nanotube composite electrodes for energy storage by supercritical fluid deposition: experiment design and device performance

    International Nuclear Information System (INIS)

    Vanadium pentoxide (V2O5) deposited on porous multiwalled carbon nanotube (MWCNT) buckypaper using supercritical fluid CO2(scCO2) deposition shows excellent performance for electrochemical capacitors. However, the low weight loading of V2O5 is one of the main problems. In this paper, design of experiments and response surface methods were employed to explore strategies for improving the active material loading by increasing the organo-vanadium precursor adsorption. A second-order response surface model was fitted to the designed experiments to predict the loading of the vanadium precursors onto carbon nanotube buckypaper as a function of time, temperature and pressure of CO2, buckypaper functionalization, precursor type, initial precursor mass and stir speed. Operation conditions were identified by employing a model that led to a precursor loading of 19.33%, an increase of 72.28% over the initial screening design. CNTs–V2O5 composite electrodes fabricated from deposited samples using the optimized conditions demonstrated outstanding electrochemical performance (947.1 F g−1 of V2O5 at a high scan rate 100 mV s−1). The model also predicted operation conditions under which light precursor aggregation took place. The V2O5 from aggregated precursor still possessed considerable specific capacitance (311 F g−1 of V2O5 at a scan rate 100 mV s−1), and the significantly higher V2O5 loading (∼81%) contributed to an increase in overall electrode capacitance. (paper)

  9. A hydrogen peroxide sensor based on a horseradish peroxidase/polyaniline/carboxy-functionalized multiwalled carbon nanotube modified gold electrode

    Energy Technology Data Exchange (ETDEWEB)

    Hua, Mu-Yi, E-mail: huamy@mail.cgu.edu.t [Green Research Center, Department of Chemical and Materials Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Biosensor Group, Biomedical Engineering Research Center, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Lin, Yu-Chen [Green Research Center, Department of Chemical and Materials Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Biosensor Group, Biomedical Engineering Research Center, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Tsai, Rung-Ywan [Electronics and Optoelectronics Research Laboratories, Industrial Technology Research Institute, 195, Sec. 4, Chung Hsing Rd., Hsinchu 31040, Taiwan (China); Chen, Hsiao-Chien; Liu, Yin-Chih [Green Research Center, Department of Chemical and Materials Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Biosensor Group, Biomedical Engineering Research Center, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China)

    2011-10-30

    We have developed a polyaniline/carboxy-functionalized multiwalled carbon nanotube (PAn/MWCNTCOOH) nanocomposite by blending the emeraldine base form of polyaniline (PAn) and carboxy-functionalized multiwalled carbon nanotubes (MWCNT) in dried dimethyl sulfoxide (DMSO) at room temperature. The conductivity of the resulting PAn/MWCNTCOOH was 3.6 x 10{sup -3} S cm{sup -1}, mainly as a result of the protonation of the PAn with the carboxyl group and the radical cations of the MWCNT fragments. Horseradish peroxidase (HRP) was immobilized within the PAn/MWCNTCOOH nanocomposite modified Au (PAn/MWCNTCOOH/Au) electrode to form HRP/PAn/MWCNTCOOH/Au for use as a hydrogen peroxide (H{sub 2}O{sub 2}) sensor. The adsorption between the negatively charged PAn/MWCNTCOOH nanocomposite and the positively charged HRP resulted in a very good sensitivity to H{sub 2}O{sub 2} and an increased electrochemically catalytical current during cyclic voltammetry. The HRP/PAn/MWCNTCOOH/Au electrode exhibited a broad linear response range for H{sub 2}O{sub 2} concentrations (86 {mu}M-10 mM). This sensor exhibited good sensitivity (194.9 {mu}A mM{sup -1} cm{sup -2}), a fast response time (2.9 s), and good reproducibility and stability at an applied potential of -0.35 V. The construction of the enzymatic sensor demonstrated the potential application of PAn/MWCNTCOOH nanocomposites for the detection of H{sub 2}O{sub 2} with high performance and excellent stability.

  10. A sensor for determination of tramadol in pharmaceutical preparations and biological fluids based on multi-walled carbon nanotubes-modified glassy carbon electrode

    International Nuclear Information System (INIS)

    A chemically modified electrode is constructed based on multi-walled carbon nanotube modified glassy carbon electrode (MWCNTs/GCE). It is demonstrated that this sensor could be used for determination of pharmaceutical important compound tramadol (TRA). The measurements were carried out using differential pulse voltammetry (DPV), cyclic voltammetry (CV) and chronoamperometry (CA) methods. DPV experiments of various concentration of TRA showed two linear dynamic ranges. The first linear dynamic range was from 4 micro M to 35 micro M, and the second linear dynamic range was between 60 micro M to 550 micro M. A detection limit of 0.38 micro M (S/N = 3) was obtained. The analytical performance of this sensor has been evaluated for the detection of TRA in human serum, human urine and some pharmaceutical preparations with satisfactory results. (author)

  11. Poly(brilliant green) and poly(thionine) modified carbon nanotube coated carbon film electrodes for glucose and uric acid biosensors.

    Science.gov (United States)

    Ghica, M Emilia; Brett, Christopher M A

    2014-12-01

    Poly(brilliant green) (PBG) and poly(thionine) (PTH) films have been formed on carbon film electrodes (CFEs) modified with carbon nanotubes (CNT) by electropolymerisation using potential cycling. Voltammetric and electrochemical impedance characterisation were performed. Glucose oxidase and uricase, as model enzymes, were immobilised on top of PBG/CNT/CFE and PTH/CNT/CFE for glucose and uric acid (UA) biosensing. Amperometric determination of glucose and UA was carried out in phosphate buffer pH 7.0 at -0.20 and +0.30 V vs. SCE, respectively, and the results were compared with other similarly modified electrodes existing in the literature. An interference study and recovery measurements in natural samples were successfully performed, indicating these architectures to be good and promising biosensor platforms. PMID:25159399

  12. Dye-Sensitized Solar Cell Based on Polyaniline/Multiwalled Carbon Nanotubes Counter Electrode

    Directory of Open Access Journals (Sweden)

    Shaker Ebrahim

    2013-01-01

    Full Text Available This work presented the successful fabrication of dye-sensitized solar cell using polyaniline base (EB, multiwalled carbon nanotubes (MWCNTs, organic dye (rhodamine B or riboflavin, zinc oxide (ZnO, and indium tin oxide (ITO. The electrical properties of the resultant devices were investigated by measuring the current density voltage (-, capacitance voltage (-, and impedance measurements under both dark and illuminated conditions. The photovoltaic cell characteristics, that is, open circuit voltage (, short circuit current density (, and energy conversion efficiency (, were evaluated under illumination and were found to be 0.48 mA/cm2, 400 mV, and 0.224%, respectively, for ITO/EB-MWCNTs/ZnO-rhodamine B/ITO heterostructure. Using impedance spectra, it was found that the series resistances of this type of solar cell are 62 and 60 Ω under darkness and illumination, respectively.

  13. Voltammetric determination of polyphenolic content in pomegranate juice using a poly(gallic acid)/multiwalled carbon nanotube modified electrode.

    Science.gov (United States)

    Abdel-Hamid, Refat; Newair, Emad F

    2016-01-01

    A simple and sensitive poly(gallic acid)/multiwalled carbon nanotube modified glassy carbon electrode (PGA/MWCNT/GCE) electrochemical sensor was prepared for direct determination of the total phenolic content (TPC) as gallic acid equivalent. The GCE working electrode was electrochemically modified and characterized using scanning electron microscope (SEM), cyclic voltammetry (CV), chronoamperometry and chronocoulometry. It was found that gallic acid (GA) exhibits a superior electrochemical response on the PGA/MWCNT/GCE sensor in comparison with bare GCE. The results reveal that a PGA/MWCNT/GCE sensor can remarkably enhance the electro-oxidation signal of GA as well as shift the peak potentials towards less positive potential values. The dependence of peak current on accumulation potential, accumulation time and pH were investigated by square-wave voltammetry (SWV) to optimize the experimental conditions for the determination of GA. Using the optimized conditions, the sensor responded linearly to a GA concentration throughout the range of 4.97 × 10(-6) to 3.38 × 10(-5) M with a detection limit of 3.22 × 10(-6) M (S/N = 3). The fabricated sensor shows good selectivity, stability, repeatability and (101%) recovery. The sensor was successfully utilized for the determination of total phenolic content in fresh pomegranate juice without interference of ascorbic acid, fructose, potassium nitrate and barbituric acid. The obtained data were compared with the standard Folin-Ciocalteu spectrophotometric results. PMID:27547628

  14. Nonenzymatic L-lysine amino acid detection using titanium oxide nanoparticles/multi wall carbon nanotube composite electrodes

    International Nuclear Information System (INIS)

    Graphical abstract: - Abstract: For the first time, a nonenzymatic electrochemical sensor for the detection of lysine was proposed based on immobilizing Multi wall carbon nanotube (MWCNT) and Titanium oxide nanoparticles (TiO2NPs) on glassy carbon (GC) electrode. Scaning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS) were used to confirm the successful stepwise assembly procedure of the sensor. The electrocatalytical behaviors of the sensor were also investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The results showed that MWCNT- TiO2NPs exhibited a remarkable electrocatalytic activity for the oxidation of lysine. Under optimal conditions, the DPV response of the sensor was proportional to the lysine concentration in the range of 500 to 5500 nanomolar with a detection limit and sensitivity of 390 nM and 0.1795 μAμM−1. This electrode show many advantages such as simple preparation without using any enzyme special electron transfer mediator or specific reagent, excellent catalytic activity at physiological pH values and antifouling property toward lysine and its oxidation product. Furthermore, the selectivity of the proposed sensor was tested in the presence of some amino acids and the response of the sensor was encountered with interferences of proline and tryptophan at equimolar concentrations

  15. Detection of Carbofuran with Immobilized Acetylcholinesterase Based on Carbon Nanotubes-Chitosan Modified Electrode

    Directory of Open Access Journals (Sweden)

    Shuping Zhang

    2013-01-01

    Full Text Available A sensitive and stable enzyme biosensor based on efficient immobilization of acetylcholinesterase (AChE to MWNTs-modified glassy carbon electrode (GCE with chitosan (CS by layer-by-layer (LBL technique for rapid determination of carbofuran has been devised. According to the inhibitory effect of carbamate pesticide on the enzymatic activity of AChE, we use carbofuran as a model pesticide. The inhibitory effect of carbofuran on the biosensor was proportional to concentration of carbofuran in the range from  g/L to  g/L with a detection limit of  g/L. This biosensor is a promising new method for pesticide analysis.

  16. Potentiometric stripping analysis of bismuth based on carbon paste electrode modified with cryptand [2.2.1] and multiwalled carbon nanotubes

    International Nuclear Information System (INIS)

    An electrochemical method based on potentiometric stripping analysis (PSA) employing a cryptand [2.2.1] (CRY) and carbon nanotube (CNT) modified paste electrode (CRY-CNT-PE) has been proposed for the subnanomolar determination of bismuth. The characterization of the electrode surface has been carried out by means of scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronocoulometry (CC). It was observed that by employing CRY-CNT-PE, a 9-fold enhancement in the PSA signal (dt/dE) was observed as compared to plain carbon paste electrode (PCPE). Under the optimized conditions, dt/dE (s/V) was proportional to the Bi(III) concentration in the range of 5.55 x 10-8 to 9.79 x 10-11 M (r = 0.9990) with the detection limit (S/N = 3) of 3.17 x 10-11 M. The practical analytical utilities of the modified electrode were demonstrated by the determination of bismuth in pharmaceutical formulations, human hair, sea water, urine and blood serum samples. The prepared modified electrode showed several advantages, such as a simple preparation method, high sensitivity, very low detection limits and excellent reproducibility. Moreover, the results obtained for bismuth analysis in commercial and real samples using CRY-CNT-PE and those obtained by atomic absorption spectroscopy (AAS) are in agreement at the 95% confidence level.

  17. A sensitive electrochemical sensor for paracetamole based on a glassy carbon electrode modified with multiwalled carbon nanotubes and dopamine nanospheres functionalized with gold nanoparticles

    International Nuclear Information System (INIS)

    We describe an electrochemical sensor for paracetamole that is based on a glassy carbon electrode modified with multiwalled carbon nanotubes and dopamine nanospheres functionalized with gold nanoparticles. The functionalized nanospheres were prepared by a chemical route and characterized by scanning electron microscopy. The well-dispersed gold nanoparticles were anchored on the dopamine nanosphere via a chemical reduction of the gold precursor. The stepwise fabrication of the modified electrode and its electrochemical response to paracetamole were evaluated using electrochemical impedance spectroscopy and cyclic voltammetry. The modified electrode displayed improved electrocatalytic activity towards paracetamole, a lower oxidation potential (371 mV), and a larger peak current when compared to a bare electrode or other modified electrodes. The kinetic parameters governing the electro-oxidation of paracetamole were studied, and the analytical conditions were optimized. The peak current was linearly related to the concentration of paracetamole in 0.8–400 μM range, and the detection limit was 50 nM (at an SNR of 3). The method was successfully applied to the determination of paracetamole in spiked human urine samples and gave recoveries between 95.3 and 105.2 %. (author)

  18. Determination of mutagenic amines in water and food samples by high pressure liquid chromatography with amperometric detection using a multiwall carbon nanotubes-glassy carbon electrode.

    Science.gov (United States)

    Bueno, Ana María; Marín, Miguel Ángel; Contento, Ana María; Ríos, Ángel

    2016-02-01

    A chromatographic method, using amperometric detection, for the sensitive determination of six representative mutagenic amines was developed. A glassy carbon electrode (GCE), modified with multiwall carbon nanotubes (GCE-CNTs), was prepared and its response compared to a conventional glassy carbon electrode. The chromatographic method (HPLC-GCE-CNTs) allowed the separation and the determination of heterocyclic aromatic amines (HAAs) classified as mutagenic amines by the International Agency for Research of Cancer. The new electrode was systematically studied in terms of stability, sensitivity, and reproducibility. Statistical analysis of the obtained data demonstrated that the modified electrode provided better sensitivity than the conventional unmodified ones. Detection limits were in the 3.0 and 7.5 ng/mL range, whereas quantification limits ranged between 9.5 and 25.0 ng/mL were obtained. The applicability of the method was demonstrated by the determination of the amines in several types of samples (water and food samples). Recoveries indicate very good agreement between amounts added and those found for all HAAs (recoveries in the 92% and 105% range). PMID:26304357

  19. Carbon nanotubes as electrode substrate material for PEM fuel cells; Kohlenstoff-Nanoroehrchen als Elektrodenmaterial fuer PEM-Brennstoffzellen

    Energy Technology Data Exchange (ETDEWEB)

    Soehn, Matthias

    2010-06-21

    This thesis reports an enhanced method to deposit nanoscaled noble metal catalysts (Pt/Ru) uniformly on carbon nanotubes based on wet chemical reduction of anorganic precursors via ethylene glycol. This well-known method is widely used to deposit noble metal catalyst particles on carbon black. Unfortunately, carbon nanotubes tend to agglomerate and therefore form bundles which cannot be penetrated by the precursor. Thus, effectiveness of the substrate is reduced. The new method prevents this by suspending the CNTs in butyl acetate by means of ultrasonic dispersion leading to a homogenous distribution. Because the butyl acetate is almost unpolar, it is nearly immiscible with the water-based ethylene glycol mixture. This problem has been solved by adding liquid Nafion {sup registered} which acts as an emulsifying agent. Thus an emulsion is created by ultrasonic treatment. This results in 30 {mu}m-sized droplets of butyl acetate with a layer of CNTs and Nafion {sup registered}. The large interface to the ethylene glycol phase yields a large surface for homogenous catalyst deposition. The prepared samples showed a narrow size distribution ({+-}0.5 nm) of small noble metal particles with loading up to 50% by weight and an average particle size of 3 nm. They are investigated using XRD, SEM, TEM, TGA-MS and CV. The added Nafion {sup registered} improves catalyst utilisation by establishing a proton conductive path to the catalyst particles. Furthermore, different manufacturing techniques for the CNT electrodes are evaluated. Thin layer Membrane-Electrode-Assemblies (MEAs) are prepared by the airbrush technique. Electrode thickness, composition and structure as well as membrane thickness is varied and the MEAs are tested in a single-cell hydrogen-oxygen-fed PEM fuel cell. The cells are characterised by cyclic IV curves which are recorded over an extended period of time, showing power densities up to 770mWcm-2 at a platinum loading of 0.3mgcm-2. Additionally, the MEAs are

  20. Preparation of glass carbon electrode modified with nanocrystalline nickel-decorated carbon nanotubes and electrocatalytic oxidation of methanol in alkaline solution

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Nanocrystalline nickel with an average diameter of about 16 nm and a face-centered cubic (fcc)structure was uniformly attached to the surface of carbon nanotubes (CNT) by wet chemistry.The sample was characterized by X-ray powder diffraction and transmission electron microscopy (TEM).A glass carbon electrode modified with nickel-modified multi-wall carbon nanotubes (MWCNTs-Ni/GCE) was prepared.The electrochemical behavior of the MWCNTs-Ni/GCE and the electrocatalytic oxidation of methanol at the MWCNTsNi/GCE were investigated by cyclic voltammetry in 1.0 mol/L NaOH solution.The cyclic voltammograms showed that the electron transfer between β-Ni(OH)2 and β-NiOOH is mainly a diffusion-controlled quasireversible process,and that the electrode has high catalytic activity for the electrooxidation of methanol in alkaline medium,revealing its potential application in alkaline rechargeable batteries and fuel cells.

  1. Plumbing carbon nanotubes

    Science.gov (United States)

    Jin, Chuanhong; Suenaga, Kazu; Iijima, Sumio

    2008-01-01

    Since their discovery, the possibility of connecting carbon nanotubes together like water pipes has been an intriguing prospect for these hollow nanostructures. The serial joining of carbon nanotubes in a controlled manner offers a promising approach for the bottom-up engineering of nanotube structures-from simply increasing their aspect ratio to making integrated carbon nanotube devices. To date, however, there have been few reports of the joining of two different carbon nanotubes. Here we demonstrate that a Joule heating process, and associated electro-migration effects, can be used to connect two carbon nanotubes that have the same (or similar) diameters. More generally, with the assistance of a tungsten metal particle, this technique can be used to seamlessly join any two carbon nanotubes-regardless of their diameters-to form new nanotube structures.

  2. Simultaneous determination of mycophenolate mofetil and its active metabolite, mycophenolic acid, by differential pulse voltammetry using multi-walled carbon nanotubes modified glassy carbon electrode

    International Nuclear Information System (INIS)

    A highly sensitive electrochemical sensor for the simultaneous determination of mycophenolate mofetil (MPM) and mycophenolic acid (MPA) was fabricated by multi-walled carbon nanotubes modified glassy carbon electrode (MWCNTs/GCE). The electrochemical behavior of these two drugs was studied at the modified electrode using cyclic voltammetry and adsorptive differential pulse voltammetry. MPM and MPA were oxidized at the GCE during an irreversible process. DPV analysis showed two oxidation peaks at 0.87 V and 1.1 V vs. Ag/AgCl for MPM and an oxidation peak at 0.87 V vs. Ag/AgCl for MPA in phosphate buffer solution of pH 5.0. The MWCNTs/GCE displayed excellent electrochemical activities toward oxidation of MPM and MPA relative to the bare GCE. The experimental design algorithm was used for optimization of DPV parameters. The electrode represents linear responses in the range 5.0 × 10−6 to 1.6 × 10−4 mol L−1 and 2.5 × 10−6 mol L−1 to 6.0 × 10−5 mol L−1 for MPM and MPA, respectively. The detection limit was found to be 9.0 × 10−7 mol L−1 and 4.0 × 10−7 mol L−1 for MPM and MPA, respectively. The modified electrode showed a good sensitivity and stability. It was successfully applied to the simultaneous determination of MPM and MPA in plasma and urine samples. - Highlights: • A new modified electrochemical sensor was constructed and used. • Multiwalled carbon nanotubes were used as the modifiers. • MPM and MPA were measured simultaneously at the low levels. • The sensor was used to the determination of MPA and MPM in real samples

  3. Electrochemiluminescence biosensor for determination of organophosphorous pesticides based on bimetallic Pt-Au/multi-walled carbon nanotubes modified electrode.

    Science.gov (United States)

    Miao, Shan Shan; Wu, Mei Sheng; Ma, Li Ya; He, Xiao Jing; Yang, Hong

    2016-09-01

    A novel and highly sensitive electrochemiluminescence (ECL) biosensing system was designed and developed for individual detection of different organophosphorous pesticides (OPs) in food samples. Bimetallic Pt-Au nanoparticles were electrodeposited on multi-walled carbon nanotubes (MWNTs)-modified glass carbon electrode (GCE) to increase the surface area of electrode and ECL signals of luminol. Biocomposites of enzymes from acetylcholinesterase and choline oxidase (AChE and ChOx) were immobilized onto the electrode surface to produce massive hydrogen peroxides (H2O2), thus amplifying ECL signals. Based on the dual-amplification effects of nanoparticles and H2O2 produced by enzymatic reactions, the proposed biosensor exhibits highly sensitivity. The proposed biosensing approach was then used for detecting OPs by inhibition of OPs on AChE. Under optimized experimental conditions, the ECL intensity decreased accordingly with the increase in concentration of OPs, and the inhibition rates of OPs were proportional to their concentrations in the range of 0.1-50nmolL(-1) for malathion, methyl parathion and chlorpyrifos, with detection limit of 0.16nmolL(-1), 0.09nmolL(-1) and 0.08nmolL(-1), respectively. The linearity range of the biosensor for pesticide dufulin varied from 50 to 500nmolL(-1), with the detection limit of 29.7nmolL(-1). The resulting biosensor was further validated by assessment of OPs residues in cabbage, which showed a fine applicability for the detection of OPs in the realistic sample. PMID:27343588

  4. Binderless Composite Electrode Monolith from Carbon Nanotube and Biomass Carbon Activated by H2 SO4 and CO2 Gas for Supercapacitor

    Science.gov (United States)

    Deraman, M.; Ishak, M. M.; Farma, R.; Awitdrus, Taer, E.; Talib, I. A.; Omar, R.

    2011-12-01

    Binderless composite electrodes in the monolithic form prepared from carbon nanotubes (CNTs) and self-adhesive carbon grains (SACG) from fibers of oil palm empty fruit bunch were studied as an electrode in a supercapacitor. The green monoliths (GMs) were prepared from three different types of precursors, SACG, SACG treated with 0.4 Molar H2 SO4 and mixture of SACG and 5% CNTs (by weight) treated with 0.4 Molar H2 SO4 , respectively. These GMs were carbonized at 600 ° C in N2 gas environment and activated by CO2 gas at 800 ° C for 1 hour to produce activated carbon monoliths (ACMs). The properties of the ACMs (density, porosity, microstructure, structure and electrical conductivity) were found affected by CNTs addition and acid treatment. The acid treatment did not improve the electrochemical behavior of the ACMs used as electrodes (specific capacitance, specific energy and specific power of the supercapacitor) in the supercapacitor cells but CNTs addition improves the equivalent series resistance of the cell.

  5. Sol-gel derived multiwalled carbon nanotubes ceramic electrode modified with molecularly imprinted polymer for ultra trace sensing of dopamine in real samples

    International Nuclear Information System (INIS)

    Highlights: → MWCNTs-CE was prepared by silane acrylate which provides a nanometer thin MIP film. → The sensor was modified by iniferter and MIP using 'surface grafting-from approach'. → A comparative study was performed between differentially designed ceramic electrodes. → The sensor can detect dopamine in real samples with LODs (0.143-0.154 ng mL-1). - Abstract: A new class of composite electrodes made of sol-gel derived ceramic-multiwalled carbon nanotubes is used for the growth of a nanometer thin film adopting 'surface grafting-from approach'. For this the multiwalled carbon nanotubes-ceramic electrode surface is first modified with an iniferter (benzyl N,N-diethyldithiocarbamate) and then dopamine imprinted polymer, under UV irradiation, for differential pulse anodic stripping voltammetric sensing of dopamine in aqueous, blood serum, cerebrospinal fluid, and pharmaceutical samples (detection limit 0.143-0.154 ng mL-1, 3σ), without any cross reactivity, interferences and false-positive contributions. Such composite electrodes offer higher stability, electron kinetics, and renewable porous surface of larger electroactive area (with insignificant capacitance) than carbon ceramic electrodes. Additional cyclic voltammetry (stripping mode) and chronocoulometry experiments were performed to explore electrodics and kinetics of electro-oxidation of dopamine.

  6. Carboxylated or Aminated Polyaniline—Multiwalled Carbon Nanotubes Nanohybrids for Immobilization of Cellobiose Dehydrogenase on Gold Electrodes

    Directory of Open Access Journals (Sweden)

    Johannes Tanne

    2014-10-01

    Full Text Available Polymer-multiwalled carbon nanotube (MWCNT nanohybrids, which differ in surface charge have been synthesized to study the bioelectrocatalysis of adsorbed cellobiose dehydrogenase (CDH from Phanerochaete sordida on gold electrodes. To obtain negatively charged nanohybrids, poly(3-amino-4-methoxybenzoic acid-co-aniline (P(AMB-A was covalently linked to the surface of MWCNTs while modification with p-phenylenediamine (PDA converted the COOH-groups to positively charged amino groups. Fourier transform infrared spectroscopy (FTIR measurements verified the p-phenylenediamine (PDA modification of the polymer-CNT nanohybrids. The positively charged nanohybrid MWCNT-P(AMB-A-PDA promoted direct electron transfer (DET of CDH to the electrode and bioelectrocatalysis of lactose was observed. Amperometric measurements gave an electrochemical response with KMapp = 8.89 mM and a current density of 410 nA/cm2 (15 mM lactose. The catalytic response was tested at pH 3.5 and 4.5. Interference by ascorbic acid was not observed. The study proves that DET between the MWCNT-P(AMB-A-PDA nanohybrids and CDH is efficient and allows the sensorial detection of lactose.

  7. Electrochemical Degradation Characteristics of Refractory Organic Pollutants in Coking Wastewater on Multiwall Carbon Nanotube-Modified Electrode

    Directory of Open Access Journals (Sweden)

    Yan Wang

    2012-01-01

    Full Text Available The multiwall carbon nanotube-mollified electrode (MWCNT-ME was fabricated and its electrocatalytic activity of refractory organic pollutants of coking wastewater was investigated. The surface morphology, absorption properties, and the electrochemical behavior of phenol and aniline at the MWCNT-ME were analyzed. Using ultraviolet-visible adsorption spectroscopy (UV-vis, Gas chromatography mass spectrometry (GC/MS, and chemical oxygen demand (COD test, the electrochemical oxidation properties of refractory organic pollutants of coking wastewater using the MWCNT-ME and the IrSnSb/Ti electrode were analyzed. Compared with the powder adsorption media, the MWCNT-ME was proved to have weaker adsorption activity, which means electrochemical degradation is the decisive factor of the removal of organic pollutants. The MWCNT-ME shows high electrochemical reactivity with oxidation peaks of 0.18 A and 0.12 A for phenol and aniline, respectively. Under the same working conditions, the MWCNT-ME COD removal rate 51% is higher than IrSnSb/Ti electrode’s rate 35%. The MWCNT-ME has application potential of electrochemical oxidation of refractory organic pollutants of coking wastewater.

  8. Highly sensitive choline biosensor based on carbon nanotube-modified Pt electrode combined with sol-gel immobilization

    Institute of Scientific and Technical Information of China (English)

    SONG Zhao; ZHAO Zixia; QIN Xia; HUANG Jiadong; SHI Haibin; WU Baoyan; CHEN Qiang

    2007-01-01

    A novel amperometric choline biosensor has been fabricated with choline oxidase (ChOx) immobilized by the sol-gel method on the surface of multi-walled carbon nanotubes (MWCNT) modified platinum electrode to improve the sensitivity and the anti-interferential property of the sensor.By analyzing the electrocatalytic activity of the modified electrode by MWCNT,it was found that MWCNT could not only improve the current response to H2O2 but also decrease the electrocatalytic potential.The effects of experimental variables such as the buffer solutions,pH and the amount of loading enzyme were investigated for the optimum analytical performance.This sensor shows sensitive determination of choline with a linear range from 5.0×10-6 to 1.0×10-4 mol/L when the operating pH and potential are 7.2 and 0.15 V,respectively.The detection limit of choline was 5.0×10-7 mol/L.Selectivity for choline was 9.48 μA.(mmol/L)-1.The biosensor exhibits excellent anti-interferential property and good stability,retaining 85% of its original current value even after a month.It has been applied to the determination of choline in human serum.

  9. Enhanced sensitivity for biosensors: Functionalized P1,5-diaminonaphthalene-multiwall carbon nanotube composite film-modified electrode

    International Nuclear Information System (INIS)

    A homogeneous electroactive poly(1,5-diaminonaphthalene) (P1,5DAN) and multiwalled carbon nanotube (MWNT) composite film-modified electrode was fabricated by cyclic voltammetry and a casting method. The dispersion and morphology of the MWNTs/P1,5DAN composite film were investigated by scanning electron microscopy. The cyclic voltammograms of the electrode modified by the MWNTs/P15DAN composite film strongly depended on the film thickness and pH of the electrolyte solution. Two absolutely isolated oxidation potentials were found as the MWCNTs were immobilized onto the surface of P1,5DAN film in a pH 6.8 buffer solution containing ascorbic acid (AA) and uric acid (UA). Both peak currents linearly increased with increased concentrations. The electrochemical behavior of UA was not interrupted even in the presence of high-concentration AA given that AA had no observable electrochemical changes at the immobilized concentration. The electrocatalytic behavior of H2O2 was also investigated by steady-state amperometry for the immobilization of horseradish peroxidase on the P1,5DAN film. The plot of the response current vs. H2O2 concentration was linear over the wide concentration range of 0.015–5.37 mM.

  10. Determination of arbutin and bergenin in Bergeniae Rhizoma by capillary electrophoresis with a carbon nanotube-epoxy composite electrode.

    Science.gov (United States)

    Zhang, Luyan; Zhang, Wei; Chen, Gang

    2015-11-10

    This report describes the fabrication and the application of a novel carbon nanotube (CNT)-epoxy composite electrode as a sensitive amperometric detector for the capillary electrophoresis (CE). The composite electrode was fabricated on the basis of the in situ polycondensation of a mixture of CNTs and 1,2-ethanediamine-containing bisphenol A epoxy resin in the inner bore of a piece of fused silica capillary under heat. It was coupled with CE for the separation and detection of arbutin and bergenin in Bergeniae Rhizoma, a traditional Chinese medicine, to demonstrate its feasibility and performance. The two phenolic constituents were well separated within 10min in a 45cm capillary length at a separation voltage of 12kV using a 50mM borate buffer (pH 9.2). The CNT-based detector offered higher sensitivity, significantly lower operating potential, satisfactory resistance to surface fouling, and lower expense of operation, indicating great promise for a wide range of analytical applications. It showed long-term stability and reproducibility with relative standard deviations of less than 5% for the peak current (n=15). PMID:26263060

  11. Square Wave Voltammetric Determination of Residues of Carbendazim Using a Fullerene/Multiwalled Carbon Nanotubes/Nafion®/Coated Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Djimadoum N. Teadoum

    2016-01-01

    Full Text Available A glassy carbon electrode (GCE was modified with a fullerene/Multiwalled Carbon Nanotubes (MWCNTs/Nafion composite and applied to the determination of carbendazim, a fungicide. The voltammetric behavior of the analyte was investigated using Cyclic Voltammetry (CV, on the bare GCE and on the same electrode coated by a thin film of the composite material. The electrode response was more than fourfold important on the modified electrode, due to electrical conductivity of fullerene and MWCNT and to favorable electrostatic interaction between the negatively charged Nafion and the protonated fungicide. A sensitive electroanalytical procedure based on Square Wave Voltammetry (SWV was then developed to detect the analyte. Under the optimum conditions, a linear relationship was obtained between the peak current and the concentration of carbendazim, in the range from 2.0 × 10−8 mol/L to 3.5 × 10−7 mol/L, leading to a detection limit of 1.7 × 10−8 mol/L and to a quantification limit of 5.57 × 10−8 mol/L. The developed procedure was successfully applied to detect carbendazim upon adsorption by some ferritic soils.

  12. Highly Conductive Aromatic Functionalized Multi-Walled Carbon Nanotube for Inkjet Printable High Performance Supercapacitor Electrodes.

    Directory of Open Access Journals (Sweden)

    Sanjeev K Ujjain

    Full Text Available We report the functionalization of multiwalled carbon nanotubes (MWCNT via the 1,3-dipolar [3+2] cycloaddition of aromatic azides, which resulted in a detangled CNT as shown by transmission electron microscopy (TEM. Carboxylic moieties (-COOH on aromatic azide result in highly stable aqueous dispersion (max. conc. ~ 10 mg/mL H2O, making the suitable for inkjet printing. Printed patterns on polyethylene terephthalate (PET flexible substrate exhibit low sheet resistivity ~65 Ω. cm, which is attributed to enhanced conductivity. Fabricated Supercapacitors (SC assembled using these printed substrates exhibit good electrochemical performance in organic as well as aqueous electrolytes. High energy and power density (57.8 Wh/kg and 0.85 kW/kg in 1M H2SO4 aqueous electrolyte demonstrate the excellent performance of the proposed supercapacitor. Capacitive retention varies from ~85-94% with columbic efficiency ~95% after 1000 charge/discharge cycles in different electrolytes, demonstrating the excellent potential of the device for futuristic power applications.

  13. Electrosorption of Os(III)-complex at single-wall carbon nanotubes immobilized on a glassy carbon electrode: Application to nanomolar detection of bromate, periodate and iodate

    Energy Technology Data Exchange (ETDEWEB)

    Salimi, Abdollah [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Research Center for Nanotechnology, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of)], E-mail: absalimi@uok.ac.ir; Kavosi, Begard [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of); Department of Chemistry, Arak University, P.O. Box, 38156-879 Arak (Iran, Islamic Republic of); Babaei, Ali [Department of Chemistry, Arak University, P.O. Box, 38156-879 Arak (Iran, Islamic Republic of); Hallaj, Rahman [Department of Chemistry, University of Kurdistan, P.O. Box 416, Sanandaj (Iran, Islamic Republic of)

    2008-06-16

    A simple procedure was developed to prepare a glassy carbon electrode modified with single-wall carbon nanotubes (SWCNTs) and Os(III)-complex. The glassy carbon (GC) electrode modified with CNTs was immersed into Os(III)-complex solution (direct deposition) for a short period of time (60 s). 1,4,8,12-Tetraazacyclotetradecane osmium(III) chloride, (Os(III)LCl{sub 2}).ClO{sub 4}, irreversibly and strongly adsorbed on SWCNTs immobilized on the surface of GC electrode. Cyclic voltammograms of the Os(III)-complex-incorporated-SWCNTs indicate a pair of well defined and nearly reversible redox couple with surface confined characteristic at wide pH range (1-8). The surface coverage ({gamma}) and charge transfer rate constant (k{sub s}) of the immobilized Os-complex on SWCNTs were 3.07 x 10{sup -9} mol cm{sup -2}, 5.5 ({+-}0.2) s{sup -1}, 2.94 x 10{sup -9} mol cm{sup -2}, 7.3 ({+-}0.3) s{sup -1} at buffer solution with pH 2 and 7, respectively, indicate high loading ability of SWCNTs for Os(III) complex and great facilitation of the electron transfer between electroactive redox center and carbon nanotubes immobilized on the electrode surface. Modified electrodes showed higher electrocatalytic activity toward reduction of BrO{sub 3}{sup -}, IO{sub 3}{sup -} and IO{sub 4}{sup -} in acidic solutions. The catalytic rate constants for catalytic reduction bromate, periodate and iodate were 3.79 ({+-}0.2) x 10{sup 3}, 7.32 ({+-}0.2) x 10{sup 3} and 1.75 ({+-}0.2) x 10{sup 3} M{sup -1} s {sup -1}, respectively. The hydrodynamic amperometry of rotating modified electrode at constant potential (0.3 V) was used for nanomolar detection of selected analytes. Excellent electrochemical reversibility of the redox couple, good reproducibility, high stability, low detection limit, long life time, fast amperometric response time, wide linear concentration range, technical simplicity and possibility of rapid preparation are great advantage of this sensor.

  14. Driving High-Performance n- and p-type Organic Transistors with Carbon Nanotube/Conjugated Polymer Composite Electrodes Patterned Directly from Solution

    KAUST Repository

    Hellstrom, Sondra L.

    2010-07-12

    We report patterned deposition of carbon nanotube/conjugated polymer composites from solution with high nanotube densities and excellent feature resolution. Such composites are suited for use as electrodes in high-performance transistors of pentacene and C60, with bottom-contact mobilities of ?0.5 and ?1 cm2 V-1 s-1, respectively. This represents a clear step towards development of inexpensive, high-performance all-organic circuits. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Transparent Electrodes with Nanotubes and Graphene for Printed Optoelectronic Applications

    Directory of Open Access Journals (Sweden)

    Marcin Słoma

    2014-01-01

    Full Text Available We report here on printed electroluminescent structures containing transparent electrodes made of carbon nanotubes and graphene nanoplatelets. Screen-printing and spray-coating techniques were employed. Electrodes and structures were examined towards optical parameters using spectrophotometer and irradiation meter. Electromechanical properties of transparent electrodes are exterminated with cyclical bending test. Accelerated aging process was conducted according to EN 62137 standard for reliability tests of electronics. We observed significant negative influence of mechanical bending on sheet resistivity of ITO, while resistivity of nanotube and graphene based electrodes remained stable. Aging process has also negative influence on ITO based structures resulting in delamination of printed layers, while those based on carbon nanomaterials remained intact. We observe negligible changes in irradiation for structures with carbon nanotube electrodes after accelerated aging process. Such materials demonstrate a high application potential in general purpose electroluminescent devices.

  16. Factors influencing MnO2/multi-walled carbon nanotubes composite's electrochemical performance as supercapacitor electrode

    International Nuclear Information System (INIS)

    Poor crystallined α-MnO2 grown on multi-walled carbon nanotubes (MWCNTs) by reducing KMnO4 in ethanol are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and Brunauer-Emmett-Telle (BET) surface area measurement, which indicate that MWCNTs are wrapped up by poor crystalline MnO2 and BET areas of the composites maintain the same level of 200 m2 g-1 as the content of MWCNTs in the range of 0-30%. The electrochemical performances of the MnO2/MWCNTs composites as electrode materials for supercapacitor are evaluated by cyclic voltammetry (CV) and galvanostatic charge-discharge measurement in 1 M Na2SO4 solution. At a scan rate of 5 mV s-1, rectangular shapes could only be observed for the composites with higher MWCNTs contents. The effect of additional conductive agent KS6 on the electrochemical behavior of the composites is also studied. With a fixed carbon content of 25% (MWCNTs included), MnO2 with 20% MWCNTs and 5% KS6 has the highest specific capacitance, excellent cyclability and best rate capability, which gives the specific capacitance of 179 F g-1 at a scan rate of 5 mV s-1, and remains 114.6 F g-1 at 100 mV s-1.

  17. Direct Electrochemistry of Hemoglobin Immobilized on a Functionalized Multi-Walled Carbon Nanotubes and Gold Nanoparticles Nanocomplex-Modified Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Nader Sheibani

    2013-07-01

    Full Text Available Direct electron transfer of hemoglobin (Hb was realized by immobilizing Hb on a carboxyl functionalized multi-walled carbon nanotubes (FMWCNTs and gold nanoparticles (AuNPs nanocomplex-modified glassy carbon electrode. The ultraviolet-visible absorption spectrometry (UV-Vis, transmission electron microscopy (TEM and Fourier transform infrared (FTIR methods were utilized for additional characterization of the AuNPs and FMWCNTs. The cyclic voltammogram of the modified electrode has a pair of well-defined quasi-reversible redox peaks with a formal potential of −0.270 ± 0.002 V (vs. Ag/AgCl at a scan rate of 0.05 V/s. The heterogeneous electron transfer constant (ks was evaluated to be 4.0 ± 0.2 s−1. The average surface concentration of electro-active Hb on the surface of the modified glassy carbon electrode was calculated to be 6.8 ± 0.3 × 10−10 mol cm−2. The cathodic peak current of the modified electrode increased linearly with increasing concentration of hydrogen peroxide (from 0.05 nM to 1 nM with a detection limit of 0.05 ± 0.01 nM. The apparent Michaelis-Menten constant (Kmapp was calculated to be 0.85 ± 0.1 nM. Thus, the modified electrode could be applied as a third generation biosensor with high sensitivity, long-term stability and low detection limit.

  18. A glassy carbon electrode modified with a polyaniline doped with silicotungstic acid and carbon nanotubes for the sensitive amperometric determination of ascorbic acid

    International Nuclear Information System (INIS)

    We report on an electrochemical sensor for the sensitive amperometric determination of ascorbic acid (AA). Aniline containing suspended silicotungstic acid and carbon nanotubes was electropolymerized on the surface of a glassy carbon electrode in a single step which provides a simple and controllable method and greatly improves the electrocatalytic oxidation of AA. The effects of scan rate, solution pH and working potential were studied. A linear relationship exists between the current measured and the concentration of AA in the range from 1 μM to 10 μM and 0.01 mM to 9 mM, with a limit of detection as low as 0.51 μM (S/N = 3). The sensor is selective, stable and satisfyingly reliable in real sample experiments. In our eyes, it has a large potential for practical applications. (author)

  19. A Novel Electrochemical Sensor for Probing Doxepin Created on a Glassy Carbon Electrode Modified with Poly(4-Amino- benzoic Acid/Multi-Walled Carbon Nanotubes Composite Film

    Directory of Open Access Journals (Sweden)

    Ji-Lie Kong

    2010-09-01

    Full Text Available A novel electrochemical sensor for sensitive detection of doxepin was prepared, which was based on a glassy carbon electrode modified with poly(4-aminobenzoic acid/multi-walled carbon nanotubes composite film [poly(4-ABA/MWNTs/GCE]. The sensor was characterized by scanning electron microscopy and electrochemical methods. It was observed that poly(4-ABA/MWNTs/GCE showed excellent preconcentration function and electrocatalytic activities towards doxepin. Under the selected conditions, the anodic peak current was linear to the logarithm of doxepin concentration in the range from 1.0 ´ 10−9 to 1.0 ´ 10−6 M, and the detection limit obtained was 1.0 × 10−10 M. The poly(4-ABA/MWNTs/GCE was successfully applied in the measurement of doxepin in commercial pharmaceutical formulations, and the analytical accuracy was confirmed by comparison with a conventional ultraviolet spectrophotometry assay.

  20. Amperometric biosensor for bisphenol A based on a glassy carbon electrode modified with a nanocomposite made from polylysine, single walled carbon nanotubes and tyrosinase

    International Nuclear Information System (INIS)

    We have prepared a nanocomposite consisting of single-walled carbon nanotubes and polylysine. It was characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, and by UV/vis and FTIR spectroscopy. Tyrosinase was covalently immobilized on the nanocomposite, and the resulting bioconjugate deposited on a glassy carbon electrode to form a biosensor for bisphenol A. The biosensor was characterized by scanning electron microscopy and electrochemical impedance spectroscopy. Under optimized experimental conditions, the biosensor gives a linear response to bisphenol A in the 4.00 nM to 11.5 μM concentration range. Its sensitivity is 788 mA M−1 cm−2, and the lower detection limit is 0.97 nM (at an S/N of 3). The biosensor shows good repeatability, reproducibility and long-term stability. In a preliminary practical application, it was successfully applied to the determination of bisphenol A in leachates of plastic spoons. (author)

  1. Voltammetric determination of bisphenol A in food package by a glassy carbon electrode modified with carboxylated multi-walled carbon nanotubes

    International Nuclear Information System (INIS)

    A highly sensitive and mercury-free method for determination of bisphenol A (BPA) was established using a glassy carbon electrode that was modified with carboxylated multi-walled carbon nanotubes. A sensitive oxidation peak is found at 550 mV in linear sweep voltammograms at pH 7. Based on this finding, trace levels of bisphenol A can be determined over a concentration range that is linear from 10 nM to 104 nM, the correlation coefficient being 0.9983, and the detection limit (S/N = 3) being 5.0 nM. The method was successfully applied to the determination of BPA in food package. (author)

  2. Gold Nanoparticle-based Layer-by-Layer Enhancement of DNA Hybridization Electrochemical Signal at Carbon Nanotube Modified Carbon Paste Electrode

    Institute of Scientific and Technical Information of China (English)

    Li Bo NIE; Jian Rong CHEN; Yu Qing MIAO; Nong Yue HE

    2006-01-01

    Colloid gold nanoparticle-based layer-by-layer amplification approach was applied to enhance the electrochemical detection sensitivity of DNA hybridization at carbon nanotube modified carbon paste electrodes (CNTPEs). Streptavidin was immobilized onto the surface of CNTPEs, and the conjugation of biotin labeled target oligonucleotides to the above immobilized streptavidin was performed, followed by the hybridization of target oligonucleotides with the gold nanoparticle-labeled DNA probe and then the layer-by-layer enhanced connection of gold nanoparticles, on which oligonucleotides complementary to the DNA probe were attached, to the hybridization system. The differential pulse voltammetry (DPV) signal of total gold nanoparticles was monitored. It was found that the layer-by-layer colloidal gold DPV detection enhanced the sensitivity by about one order of magnitude compared with that of one-layer detection. One-base mismatched DNA and complementary DNA could be distinguished clearly.

  3. A glassy carbon electrode modified with a multiwalled carbon nanotube-reduced graphene oxide nanoribbon core-shell structure for electrochemical sensing of p-dihydroxybenzene

    International Nuclear Information System (INIS)

    Multiwalled carbon nanotubes (MWCNT) were covered with reduced graphene oxide nanoribbons (rGONR) to give a material with a core-shell heterostructure of the type MWCNT-rGONR. It was obtained by (a) longitudinal partial unzipping of MWCNT to form MWCNT-GONR, and (b) subsequent chemical reduction with hydrazine to give MWCNT-rGONR. The MWCNT-rGONR heterostructure was used to modify a glassy carbon electrode (GCE) to obtain an electrochemical sensor for p-dihydroxybenzene (DHB). The synergistic effects of the MWCNT and the rGONR results in a distinctly improved redox current towards DHB compared to a bare GCE, an MWCNT/GCE, and an MWCNT-GONR/GCE. At the working voltage range from −100 to 400 mV, it displays a linear response to DHB in the 80 to 3000 nM concentration range with a 20 nM detection limit. (author)

  4. Square wave anodic stripping voltammetric determination of lead(II) using a glassy carbon electrode modified with a lead ionophore and multiwalled carbon nanotubes

    International Nuclear Information System (INIS)

    We report on a glassy carbon electrode (GCE) modified with a lead ionophore and multiwalled carbon nanotubes. It can be applied to square wave anodic stripping voltammetric determination of Pb(II) ion after preconcentration of Pb(II) at -1. 0 V (vs. SCE) for 300 s in pH 4. 5 acetate buffer containing 400 μg L-1 of Bi(III). The ionophore-MWCNTs film on the GCE possesses strong and highly selective affinity for Pb(II) as confirmed by quartz crystal microbalance experiments. Under the optimum conditions, a linear response was observed for Pb(II) ion in the range from 0. 3 to 50 μg L-1. The limit of detection (at S/N = 3) is 0. 1 μg L-1. The method was applied to the determination of Pb(II) in water samples with acceptable recovery. (author)

  5. Dielectrophoretic assembly of carbon nanotube devices

    OpenAIRE

    Dimaki, Maria; BØGGILD, Peter

    2004-01-01

    The purpose of this project has been to assemble single-walled carbon nanotubes on electrodes at the tip of a biocompatible cantilever and use these for chemical species sensing in air and liquid, for example in order to measure the local activity from ion channels in the cell membrane. The electrical resistance of carbon nanotubes has been shown to be extremely sensitive to gas molecules. Dielectrophoresis is a method capable of quickly attracting nanotubes on microelectrodes by using an ele...

  6. Biosensor based on tyrosinase immobilized on a single-walled carbon nanotube-modified glassy carbon electrode for detection of epinephrine

    Directory of Open Access Journals (Sweden)

    Apetrei IM

    2013-11-01

    Full Text Available Irina Mirela Apetrei,1 Constantin Apetrei21Department of Pharmaceutical Sciences, Faculty of Medicine and Pharmacy, 2Department of Chemistry, Physics and Environment, Faculty of Sciences and Environment, Dunarea de Jos University of Galati, RomaniaAbstract: A biosensor comprising tyrosinase immobilized on a single-walled carbon nanotube-modified glassy carbon electrode has been developed. The sensitive element, ie, tyrosinase, was immobilized using a drop-and-dry method followed by cross-linking. Tyrosinase maintained high bioactivity on this nanomaterial, catalyzing the oxidation of epinephrine to epinephrine-quinone, which was electrochemically reduced (-0.07 V versus Ag/AgCl on the biosensor surface. Under optimum conditions, the biosensor showed a linear response in the range of 10–110 µM. The limit of detection was calculated to be 2.54 µM with a correlation coefficient of 0.977. The repeatability, expressed as the relative standard deviation for five consecutive determinations of 10-5 M epinephrine solution was 3.4%. A good correlation was obtained between results obtained by the biosensor and those obtained by ultraviolet spectrophotometric methods.Keywords: amperometry, single-walled carbon nanotubes, spectrophotometry, catecholamine, pharmaceutical formula

  7. Controlled Deposition and Alignment of Carbon Nanotubes

    Science.gov (United States)

    Smits, Jan M. (Inventor); Wincheski, Russell A. (Inventor); Patry, JoAnne L. (Inventor); Watkins, Anthony Neal (Inventor); Jordan, Jeffrey D. (Inventor)

    2012-01-01

    A carbon nanotube (CNT) attraction material is deposited on a substrate in the gap region between two electrodes on the substrate. An electric potential is applied to the two electrodes. The CNT attraction material is wetted with a solution defined by a carrier liquid having carbon nanotubes (CNTs) suspended therein. A portion of the CNTs align with the electric field and adhere to the CNT attraction material. The carrier liquid and any CNTs not adhered to the CNT attraction material are then removed.

  8. Electrochemical behavior of propranolol hydrochloride in neutral solution on platinum nanoparticles doped multi-walled carbon nanotubes modified glassy carbon electrode

    International Nuclear Information System (INIS)

    Graphical abstract: PtNPs/MWCNTs has been successfully stabilized onto the surface of GCE and used for electrochemical determination of PRO as a sensor. The results showed that the oxidation of PRO was catalyzed by PtNPs/MWCNTs film in neutral environment and that the peak potential of PRO was shifted to 1.10 V. Highlights: ► Pt nanoparticles and multi-walled carbon nanotubes mixture as the electrode modified material. ► The modified material doped directly onto the electrode surface. ► Detected in the neutral environment. - Abstract: Platinum nanoparticles (PtNPs) were used in combination with multi-walled carbon nanotubes (MWCNTs) with Nafion as the adhesives for fabricating sensitivity-enhanced electrochemical propranolol hydrochloride (PRO) sensor. The modifier, PtNPs doped MWCNTs (PtNPs/MWCNTs), was characterized by transmission electron microscopy (TEM) and electrochemical method which showed an excellent character for electrocatalytic oxidization of PRO. In addition, the experimental parameters such as pH values, the concentration of PtNPs/MWCNTs and the scan rate were optimized. Due to the fine characteristics of PtNPs/MWCNTs, a good linear relationship between the anodic peak current and PRO concentration in the range 6.76 × 10−7–3.8 × 10−5 M was observed. The detection limit of 8.45 × 10−8 M was achieved with the linear correlation coefficient R = 0.9965. The relative standard derivation was 2.74% for 3.38 10−6 M PRO in 11 repeated determinations. This modified electrode showed excellent sensitivity and stability for the determination of PRO.

  9. Electrochemical Characterization and Determination of Phenol and Chlorophenols by Voltammetry at Single Wall Carbon Nanotube/Poly(3,4-ethylenedioxythiophene) Modified Screen Printed Carbon Electrode

    Science.gov (United States)

    Negash, Negussie; Alemu, Hailemichael; Tessema, Merid

    2015-01-01

    Screen printed carbon electrode (SPCE) has been modified with single wall carbon nanotube/poly(3,4-ethylenedioxythiophene) (SWCNT/PEDOT) composites for the determination of phenol and chlorophenols (phenol, 4-chlorophenol, 2,4-dichlorophenol, and 2,4,6-trichlorophenol). The effect of the modifiers on the electrode characteristics was evaluated and the responses were optimized for the voltammetric determination of phenol and chlorophenols. The parameters affecting the responses such as pH, scan rate, and stability were studied. The analytical performance of the SWCNT/PEDOT/SPCE using cyclic voltammetry was tested and found to be impressive. Under these conditions, the designed electrode showed a good performance for the voltammetric measurements of the phenolic compounds. The modified SPCE, when it is compared with other enzymatic and nonenzymatic sensors, showed a wider dynamic range for the detection of the phenolic compounds. The modified SPCE was used for the quantification of phenol in water samples. The results suggest that the method is quite useful for analyzing and monitoring phenols and chlorophenols. PMID:27347519

  10. Nonenzymatic sensing of glucose using a carbon ceramic electrode modified with a composite film made from copper oxide, over oxidized polypyrrole and multi-walled carbon nanotubes

    International Nuclear Information System (INIS)

    A carbon ceramic electrode was modified with a thin film composed of over oxidized polypyrrole, CuO and multi-walled carbon nanotubes. The surface morphology, electrochemical properties and electrocatalytic activity towards the oxidation of glucose of the modified electrode were studied in detail. Benefiting from the high electrocatalytic activity of CuO, the selectivity of OPpy film, and the fast electron transfer rate promoted by MWCNTs, this modified electrode displays good stability, selectivity, high electrocatalytic activity and a low detection limit for the determination of glucose in pH 13 solution. Under the optimum conditions, the linear range for the determination of glucose by cyclic voltammetry is from 20 μM to 10 mM, and the detection limit is 4.0 μM (at an SNR of 3). The amperometric calibration plot covers the 0.20 μM to 2.0 mM concentration range, and the detection limit is 50 nM. The highest sensitivity for the determination of glucose is 3922.6 μA mM−1 cm2. (author)

  11. An amperometric penicillin biosensor with enhanced sensitivity based on co-immobilization of carbon nanotubes, hematein, and {beta}-lactamase on glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Chen Bi; Ma Ming [Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081 (China); Su Xiaoli, E-mail: xsu@hunnu.edu.cn [Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (Ministry of Education of China), College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081 (China)

    2010-07-26

    An amperometric penicillin biosensor with enhanced sensitivity was successfully developed by co-immobilization of multi-walled carbon nanotubes (MWCNTs), hematein, and {beta}-lactamase on glassy carbon electrode using a layer-by-layer assembly technique. Under catalysis of the immobilized enzyme, penicillin was hydrolyzed, decreasing the local pH. The pH change was monitored amperometrically with hematein as a pH-sensitive redox probe. MWCNTs were used as an electron transfer enhancer as well as an efficient immobilization matrix for the sensitivity enhancement. The effects of immobilization procedure, working potential, enzyme quantity, buffer concentration, and sample matrix were investigated. The biosensor offered a minimum detection limit of 50 nM (19 {mu}g L{sup -1}) for penicillin V, lower than those of the conventional pH change-based biosensors by more than two orders of magnitude. The electrode-to-electrode variation of the response sensitivity was 7.0% RSD.

  12. Direct electrochemistry and electrocatalysis of hemoglobin with carbon nanotube-ionic liquid-chitosan composite materials modified carbon ionic liquid electrode

    International Nuclear Information System (INIS)

    A novel composite biomaterial was prepared by combining chitosan, multi-walled carbon nanotubes (MWCNTs), hemoglobin (Hb) and ionic liquid (IL) 1-butyl-3-methyl-imidazolium bromide together, which was further modified on the surface of a carbon ionic liquid electrode (CILE) with another ionic liquid 1-ethyl-3-methylimidazolium ethylsulphate as the binder. Ultraviolet-visible and Fourier transform infrared spectroscopic results indicated that Hb molecules in the composite film retained the native structure. Cyclic voltammetric results showed that a pair of well-defined redox peaks appeared in 0.1 mol/L phosphate buffer solution, indicating that the direct electron transfer of Hb in the composite film with the underlying electrode was realized. The results were attributed to the synergistic effect of MWCNTs and IL in the composite film, which promoted the electron transfer rate of Hb. The composite material modified electrode showed excellent electrocatalytic ability towards the reduction of different substrates such as trichloroacetic acid and NaNO2 with good stability and reproducibility.

  13. An electrochemical sensor for rizatriptan benzoate determination using Fe3O4 nanoparticle/multiwall carbon nanotube-modified glassy carbon electrode in real samples.

    Science.gov (United States)

    Madrakian, Tayyebeh; Maleki, Somayeh; Heidari, Mozhgan; Afkhami, Abbas

    2016-06-01

    In this paper a sensitive and selective electrochemical sensor for determination of rizatriptan benzoate (RZB) was proposed. A glassy carbon electrode was modified with nanocomposite of multiwalled carbon nanotubes (MWCNTs) and Fe3O4 nanoparticles (Fe3O4/MWCNTs/GCE). The results obtained clearly show that the combination of MWCNTs and Fe3O4 nanoparticles definitely improves the sensitivity of modified electrode to RZB determination. The morphology and electroanalytical performance of the fabricated sensor were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), square wave voltammetry (SWV) and cyclic voltammetry (CV). Also, the effect of experimental and instrumental parameters on the sensor response was evaluated. The square wave voltammetric response of the electrode to RZB was linear in the range 0.5-100.0μmolL(-1) with a detection limit of 0.09μmolL(-1) under the optimum conditions. The investigated method showed good stability, reproducibility and repeatability. The proposed sensor was successfully applied for real life samples of blood serum and RZB determination in pharmaceutical. PMID:27040259

  14. Simple flow injection for determination of sulfite by amperometric detection using glassy carbon electrode modified with carbon nanotubes-PDDA-gold nanoparticles.

    Science.gov (United States)

    Amatatongchai, Maliwan; Sroysee, Wongduan; Chairam, Sanoe; Nacapricha, Duangjai

    2015-02-01

    A new approach is presented for sensitive and selective measurement of sulfite (SO3(2-)) in beverages based on a simple flow injection system with amperometric detection. In this work, the sulfite sensor was a glassy carbon electrode modified with multiwall carbon nanotubes-poly(diallyldimethylammonium chloride)-gold nanoparticles composites (CNTs-PDDA-AuNPs/GC). Electrochemical oxidation of sulfite with this electrode was first studied in 0.1M phosphate buffer (pH 7.0) using cyclic voltammetry. The results indicated that the CNTs-PDDA-AuNPs/GC electrode possesses electrocatalytic activity for the oxidation of sulfite with high sensitivity and selectivity. Sulfite was quantified using amperometric measurement with the new sensor at +0.4V vs Ag/AgCl in conjunction with flow injection. The linear working range for the quantitation of sulfite was 2-200 mg L(-1) (r(2)=0.998) with a detection limit of 0.03 mg L(-1) (3σ of blank) and an estimated precision of 1.5%.The proposed method was successfully applied to the determination of sulfite in fruit juices and wines with a sample throughput of 23 samples per hour. PMID:25435239

  15. Immunoassay for serum amyloid A using a glassy carbon electrode modified with carboxy-polypyrrole, multiwalled carbon nanotubes, ionic liquid and chitosan

    International Nuclear Information System (INIS)

    We report on a highly sensitive electrochemical immunoassay for the serum inflammation marker amyloid A (SAA). It is making use of a glassy carbon electrode that was modified with carboxy-endcapped polypyrrole (PPy-α-COOH), multiwalled carbon nanotubes (MWCNTs), ionic liquid and chitosan acting as the support platform. The nanocomposite increases the sensitivity and stability of the assay. Antibody against SAA was immobilized on a monolayer surface consisting of PPy-α-COOH. The electrode material was characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectra, cyclic voltammetry, electrochemical impedance spectroscopy and differential pulse voltammetry. The calibration plot for this assay, when operated at 0.16 V (vs. SCE) and applied to spiked serum samples, is linear in the 0.001 to 900 ng mL−1 SAA concentration range, and the detection limit is as low as 0.3 pg mL−1 (at an S/N ratio of 3). The electrode is stable and highly sensitive. The detection scheme is likely to be applicable to numerous other kinds of immunoassays. (author)

  16. Comparison of amperometric biosensors fabricated by palladium sputtering, palladium electrodeposition and Nafion/carbon nanotube casting on screen-printed carbon electrodes.

    Science.gov (United States)

    Lee, Chung-Hun; Wang, Shih-Chang; Yuan, Chiun-Jye; Wen, Meng-Fang; Chang, Ku-Shang

    2007-01-15

    Different strategies, including palladium electrodeposition (Pd(CV)), Pd sputtering (Pd(S)) and Nafion-solubilized carbon nanotube casting (Nafion/CNT), were used to modify screen-printed carbon electrodes (SPCEs) for the fabrication of amperometric enzyme biosensors. The electrochemical properties of the bare and modified SPCEs and the optimal conditions for surface modification were determined. The electrochemical response of the bare SPCE to H(2)O(2) under the potential of 0.3 V could be improved about 100-fold by Pd modification by electrodeposition or sputtering. By contrast, the electrochemical response of the bare SPCE was enhanced by only about 11-fold by Nafion/CNT casting. Moreover, the Pd(CV)-SPCEs exhibited better reproducibility of electrochemical response (a relative standard deviation (R.S.D.)10%). The glucose biosensor fabricated from Pd-modified electrodes could be stored for up to 108 days without loosing significant activity. The Pd(CV)-SPCE also showed very reliable signal characteristics upon 50 consecutively repeated measurements of ascorbic acid. The electrocatalytic detection of the Pd-SPCE was combined with additional advantages of resistance to surface fouling and hence good stability. In conclusion, this study demonstrated that deposition of Pd thin film on SPCEs by electrodeposition or sputtering provided superior enhancement of electrochemical properties compared to Nafion/CNT-SPCEs. Despite their high electrochemical response, Pd(S)-SPCEs required an activation process to improve stability and Pd(CV)-SPCEs suffered from poor between electrode reproducibility. PMID:16644200

  17. Preparation of Ni(OH)2-graphene sheet-carbon nanotube composite as electrode material for supercapacitors

    International Nuclear Information System (INIS)

    Highlights: • CNT is introduced into graphene to prevent restacking by solvothermal reaction. • Ethanol as a low cost and green solvent is used in solvothermal reaction. • Ni(OH)2 nanosheets were chemically precipitated into GS-CNT to increase the capacitance. - Abstract: Ni(OH)2-graphene sheet-carbon nanotube composite was prepared for supercapacitance materials through a simple two-step process involving solvothermal synthesis of graphene sheet-carbon nanotube composite in ethanol and chemical precipitation of Ni(OH)2. According to N2 adsorption/desorption analysis, the Brunauer–Emmett–Teller surface area of graphene sheet-carbon nanotube composite (109.07 m2 g−1) was larger than that of pure graphene sheets (32.06 m2 g−1), indicating that the added carbon nanotubes (15 wt.%) could prevent graphene sheets from restacking in the solvothermal reaction. The results of field emission scanning electron microscopy and transmission electron microscopy showed that Ni(OH)2 nanosheets were uniformly loaded into the three-dimensional interconnected network of graphene sheet-carbon nanotube composite. The microstructure enhanced the rate capability and utilization of Ni(OH)2. The specific capacitance of Ni(OH)2-graphene sheet-carbon nanotube composite was 1170.38 F g−1 at a current density of 0.2 A g−1 in the 6 mol L−1 KOH solution, higher than those provided by pure Ni(OH)2 (953.67 Fg−1) and graphene sheets (178.25 F g−1). After 20 cycles at each current density (0.2, 0.4, 0.6, 0.8, 1.0 and 1.2 A g−1), the capacitance of Ni(OH)2-graphene sheet-carbon nanotube composite decreased 26.96% of initial capacitance compared to 74.52% for pure Ni(OH)2

  18. Carbon nanotubes decorating methods

    OpenAIRE

    A.D. Dobrzańska-Danikiewicz; D. Łukowiec; D. Cichock; W. Wolany

    2013-01-01

    Purpose: The work is to present and characterise various methods of depositing carbon nanotubes with nanoparticles of precious metals, and also to present the results of own works concerning carbon nanotubes coated with platinum nanoparticles.Design/methodology/approach: Electron transmission and scanning microscopy has been used for imaging the structure and morphology of the nanocomposites obtained and the distribution of nanoparticles on the surface of carbon nanotubes.Findings: The studie...

  19. Functionalization of Carbon Nanotubes

    OpenAIRE

    Abraham, Jürgen

    2005-01-01

    Carbon nanotubes have an enormous potential due to their outstanding electronic, optical, and mechanical properties. However, any technological application is still hindered due to problems regarding the processibility of the pristine carbon nanotubes. In the past few years, it has been shown that the chemical modification of the carbon nanotubes is an inevitable step prior to their application. The first part of this work (chapter 3.1) was focused on the purification of pristine laser ablati...

  20. Preparation of a sol-gel-derived carbon nanotube ceramic electrode by microwave irradiation and its application for the determination of adenine and guanine

    Energy Technology Data Exchange (ETDEWEB)

    Abbaspour, Abdolkarim, E-mail: abbaspour@chem.susc.ac.i [Department of Chemistry, College of Sciences, Shiraz University, Shiraz, Fars 71456-85464 (Iran, Islamic Republic of); Ghaffarinejad, Ali [Department of Chemistry, College of Sciences, Shiraz University, Shiraz, Fars 71456-85464 (Iran, Islamic Republic of)

    2010-01-01

    In this study, microwave irradiation was used for the fast preparation (min) of a sol-gel-derived carbon nanotube ceramic electrode (MW-CNCE). For confirmation of the preparation of the ceramic by MW irradiation, Fourier transform infrared, X-ray diffraction spectra and scanning electron microscopy images of the produced ceramic were compared with those of conventional ceramic (which is produced by drying the ceramic in air for 48 h). The electrochemical behavior of MW-CNCE in nicotinamide adenine dinucleotide, L-cysteine, adenine and guanine was compared with that of a conventional sol-gel-derived carbon nanotube ceramic electrode (CNCE). In all systems, similar peak potentials and lower background currents were obtained with respect to CNCE. Finally, the MW-CNCE was used for the simultaneous determination of adenine and guanine using differential pulse voltammetry. The linear ranges of 0.1-10 and 0.1-20 muM were obtained for adenine and guanine, respectively. These results are comparable with some modified electrodes that have recently been reported for the determination of adenine and guanine, with the advantage that the proposed electrode did not contain modifier. In addition, the proposed electrode was successfully used for the oxidation of adenine and guanine in DNA, and the detection limit for this measurement was 0.05 mug mL{sup -1} DNA.

  1. Simulation and modelling of charge transport in dye-sensitized solar cells based on carbon nano-tube electrodes

    International Nuclear Information System (INIS)

    For a better understanding of the mechanisms of dye-sensitized solar cells (DSSCs), based on carbon nano-tube (CNT) electrodes, a phenomenological model is proposed. For modelling purposes, the meso-scopic porous CNT electrode is considered as a homogeneous nano-crystalline structure with thickness L. The CNT electrode is covered with light-absorbing dye molecules, and interpenetrated by the tri-iodide (I−/I3−) redox couple. A simulation platform, designed to study coupled charge transport in such cells, is presented here. The work aims at formulating a mathematical model that describes charge transfer and charge transport within the porous CNT window electrode. The model is based on a pseudo-homogeneous active layer using drift–diffusion transport equations for free electron and ion transport. Based on solving the continuity equation for electrons, the model uses the numerical finite difference method. The numerical solution of the continuity equation produces current–voltage curves that fit the diode equation with an ideality factor of unity. The calculated current–voltage (J–V) characteristics of the illuminated idealized DSSCs (100 mW cm−2, AM1.5), and the different series resistances of the transparent conductor oxide (TCO) layer were introduced into the idealized simulated photo J–V characteristics. The results obtained are presented and discussed in this paper. Thus, for a series resistance of 4 Ω of the TCO layer, the conversion efficiency (η) was 7.49% for the CNT-based cell, compared with 6.11% for the TiO2-based cell. Two recombination kinetic models are used, the electron transport kinetics within the nano-structured CNT film, or the electron transfer rate across the CNT–electrolyte interface. The simulations indicate that both electron and ion transport properties should be considered when modelling CNT-based DSSCs and other similar systems. Unlike conventional polycrystalline solar cells which exhibit carrier recombination, which

  2. Direct electron transfer and biosensing of glucose oxidase immobilized at multiwalled carbon nanotube-alumina-coated silica modified electrode

    International Nuclear Information System (INIS)

    Investigations are reported regarding the direct electrochemical performance of glucose oxidase (GOD) immobilized on a film of multiwalled carbon nanotube-alumina-coated silica (MWCNT-ACS). The surface morphology of the GOD/MWCNT-ACS nanobiocomposite is characterized by scanning electron microscopy. In cyclic voltammetric response, the immobilized GOD displays a pair of well-defined redox peaks, with a formal potential (E°′) of − 0.466 V versus Ag/AgCl in a 0.1 M phosphate buffer solution (pH 7.5) at a scan rate of 0.05 V s−1; also the electrochemical response indicates a surface-controlled electrode process. The dependence of formal potential on solution pH indicates that the direct electron transfer reaction of GOD is a reversible two-electron coupled with a two-proton electrochemical reaction process. The glucose biosensor based on the GOD/MWCNT-ACS nanobiocomposite shows a sensitivity of 0.127 A M−1 cm−2 and an apparent Michaelis–Menten constant of 0.5 mM. Furthermore, the prepared biosensor exhibits excellent anti-interference ability to the commonly co-existed uric acid and ascorbic acid. - Highlights: ► A film composed of MWCNT-ACS was used for biosensor application. ► High sensitivity and good selectivity were obtained for the detection of glucose. ► This approach is potential for fabrication of mediator-free biosensor.

  3. The development of chloride ion selective polypyrrole thin film on a layer-by-layer carbon nanotube working electrode

    Science.gov (United States)

    Liu, Yang; Lynch, Jerome

    2011-04-01

    A chloride ion selective thin film sensor is proposed for measuring chloride ion concentration, which is an environmental parameter correlated to corrosion. In this work, electrochemical polymerization of Polypyrrole (PPy) doped with chloride ions was achieved on the top of a carbon nanotube (CNT) thin film as a working electrode in an electrochemical cell. The underlying CNT layer conjugated with doped PPy thin film can form a multifunctional "selfsensing" material platform for chloride ion detection in a concrete environment. The paper presents the first type of work using CNT and PPy as hybrid materials for chloride ion sensing. Electrochemical polymerization of PPy results in oxidation that yields an average of one positive charge distributed over four pyrrole units. This positive charge is compensated by negatively-charged chloride ions in the supporting electrolyte. In effect, the chloride ion-doped PPy has become molecularly imprinted with chloride ions thereby providing it with some degree of perm-selectivity for chloride ions. The detection limit of the fabricated chloride ion-doped PPy thin film can reach 10-8 M and selectivity coefficients are comparable to those in the literature. The reported work aims to lay a strong foundation for detecting chloride ion concentrations in the concrete environment.

  4. A stretchable polymer-carbon nanotube composite electrode for flexible lithium-ion batteries: porosity engineering by controlled phase separation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hojun; Yoo, Jung-Keun; Jung, Yeon Sik [Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon (Korea, Republic of); Park, Jong-Hyun [Material R and D Department, LG Display Co., Ltd., Paju-si, Gyeonggi-do (Korea, Republic of); Kim, Jin Ho [Icheon Branch, Korea Institute of Ceramic Engineering and Technology, Icheon-si, Gyeonggi-do (Korea, Republic of); Kang, Kisuk [Department of Materials Science and Engineering, Seoul National University, Seoul (Korea, Republic of)

    2012-08-15

    Flexible energy-storage devices have attracted growing attention with the fast development of bendable electronic systems. However, it still remains a challenge to find reliable electrode materials with both high mechanical flexibility/toughness and excellent electron and lithium-ion conductivity. This paper reports the fabrication and characterization of highly porous, stretchable, and conductive polymer nanocomposites embedded with carbon nanotubes (CNTs) for application in flexible lithium-ion batteries. The systematic optimization of the porous morphology is performed by controllably inducing the phase separation of polymethylmethacrylate (PMMA) in polydimethylsiloxane (PDMS) and removing PMMA, in order to generate well-controlled pore networks. It is demonstrated that the porous CNT-embedded PDMS nanocomposites are capable of good electrochemical performance with mechanical flexibility, suggesting these nanocomposites could be outstanding anode candidates for use in flexible lithium-ion batteries. The optimization of the pore size and the volume fraction provides higher capacity by nearly seven-fold compared to a nonporous nanocomposite. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Electrochemical Characterization of O2 Plasma Functionalized Multi-Walled Carbon Nanotube Electrode for Legionella pneumophila DNA Sensor

    Science.gov (United States)

    Park, Eun Jin; Lee, Jun-Yong; Hyup Kim, Jun; Kug Kim, Sun; Lee, Cheol Jin; Min, Nam Ki

    2010-08-01

    An electrochemical DNA sensor for Legionella pneumophila detection was constructed using O2 plasma functionalized multi-walled carbon nanotube (MWCNT) film as a working electrode (WE). The cyclic voltammetry (CV) results revealed that the electrocatalytic activity of plasma functionalized MWCNT (pf-MWCNT) significantly changed depending on O2 plasma treatment time due to some oxygen containing functional groups on the pf-MWCNT surface. Scanning electron microscope (SEM) images and X-ray photoelectron spectroscopy (XPS) spectra were also presented the changes of their surface morphologies and oxygen composition before and after plasma treatment. From a comparison study, it was found that the pf-MWCNT WEs had higher electrocatalytic activity and more capability of probe DNA immobilization: therefore, electrochemical signal changes by probe DNA immobilization and hybridization on pf-MWCNT WEs were larger than on Au WEs. The pf-MWCNT based DNA sensor was able to detect a concentration range of 10 pM-100 nM of target DNA to detect L. pneumophila.

  6. Tubular carbon nanotube-based gas diffusion electrode removes persistent organic pollutants by a cyclic adsorption - Electro-Fenton process.

    Science.gov (United States)

    Roth, Hannah; Gendel, Youri; Buzatu, Pompilia; David, Oana; Wessling, Matthias

    2016-04-15

    We report a novel tubular electrochemical cell which is operated in a cyclic adsorption - electro-Fenton process and by this means overcomes the drawbacks of the traditional electro-Fenton process. A microtube made only of multi-walled carbon nanotubes (MWCNT) functions as a gas diffusion electrode (GDE) and highly porous adsorber. In the process, the pollutants were first removed electroless from the wastewater by adsorption on the MWCNT-GDE. Subsequently, the pollutants are electrochemically degraded in a defined volume of electrolyte solution using the electro-Fenton process. Oxygen was supplied into the lumen of the saturated microtubular GDE which was surrounded by a cylindrical anode made of Ti-felt coated with Pt/IrO2 catalysts. For the proof of concept the model pollutant Acid Red 14 (AR14), an azo dye, was used. The decomposition of AR14 was studied at different applied current densities and initial concentrations of ferrous iron in the electrolyte solution. At optimal conditions, complete regeneration of the adsorption capacity of the MWCNT-GDE, complete decolorization and TOC and COD removal rates of 50% and 70% were achieved, respectively. The MWCNT-GDE is regenerated and again available for adsorption. This approach allows water treatment independent of its composition, thus does not require any addition of chemicals to the wastewater. PMID:26775104

  7. Multiwalled carbon nanotube coated polyester fabric as textile based flexible counter electrode for dye sensitized solar cell.

    Science.gov (United States)

    Arbab, Alvira Ayoub; Sun, Kyung Chul; Sahito, Iftikhar Ali; Qadir, Muhammad Bilal; Jeong, Sung Hoon

    2015-05-21

    Textile wearable electronics offers the combined advantages of both electronics and textile characteristics. The essential properties of these flexible electronics such as lightweight, stretchable, and wearable power sources are in strong demand. Here, we have developed a facile route to fabricate multi walled carbon nanotube (MWCNT) coated polyester fabric as a flexible counter electrode (CE) for dye sensitized solar cells (DSSCs). A variety of MWCNT and enzymes with different structures were used to generate individual enzyme-dispersed MWCNT (E-MWCNT) suspensions by non-covalent functionalization. A highly concentrated colloidal suspension of E-MWCNT was deposited on polyester fabric via a simple tape casting method using an air drying technique. In view of the E-MWCNT coating, the surface structure is represented by topologically randomly assembled tubular graphene units. This surface morphology has a high density of colloidal edge states and oxygen-containing surface groups which execute multiple catalytic sites for iodide reduction. A highly conductive E-MWCNT coated fabric electrode with a surface resistance of 15 Ω sq(-1) demonstrated 5.69% power conversion efficiency (PCE) when used as a flexible CE for DSSCs. High photo voltaic performance of our suggested system of E-MWCNT fabric-based DSSCs is associated with high sheet conductivity, low charge transfer resistance (RCT), and excellent electro catalytic activity (ECA). Such a conductive fabric demonstrated stable conductivity against bending cycles and strong mechanical adhesion of E-MWCNT on polyester fabric. Moreover, the polyester fabric is hydrophobic and, therefore, has good sealing capacity and retains the polymer gel electrolyte without seepage. This facile E-MWCNT fabric CE configuration provides a concrete fundamental background towards the development of textile-integrated solar cells. PMID:25912056

  8. Preparation of Ti/SnO2-Sb electrodes modified by carbon nanotube for anodic oxidation of dye wastewater and combination with nanofiltration

    International Nuclear Information System (INIS)

    Highlights: • Ti/SnO2-Sb-CNT electrodes were prepared by pulse electrodeposition technology. • The characteristics of Ti/SnO2-Sb-CNT was compared with Ti/SnO2-Sb. • We combined electro-catalytic oxidation with NF to treat dye wastewater. - Abstract: A new type of Ti/SnO2-Sb electrode modified with carbon nanotube (CNT) has been fabricated using a pulse electrodeposition method. The electrode modified with CNT versus without CNT has larger surface area and smaller crystallite particles (41.9 nm versus 46.8 nm) as seen by scanning electron microscopy (SEM), and calculated through X-ray diffraction (XRD), respectively. It means that the CNT-modified electrode can provide more active sites for electrochemical oxidation of organic pollutants. Oxygen evolution potential of the CNT-modified electrode has 0.07 V higher overpotential in the Linear sweep voltammetry (LSV) curve. The service lifetime of Ti/SnO2-Sb-CNT electrode is 4.8 times longer than that of the Ti/SnO2-Sb electrode without CNT modifying. The Ti/SnO2-Sb-CNT electrode is demonstrated to have a superior electrochemical oxidation and degradation abilities using Acid Red 73 (AR 73) as a model organic pollutant. The CNT-modified electrode has higher kinetic rate constant, chemical oxygen demand (COD) and total organic carbon (TOC) removals, and mineralization current efficiency, which is 1.93, 1.27, 1.26, and 1.38 times those of the Ti/SnO2-Sb electrode, respectively. The repeated experiments prove the reproducibility of the data. Ti/SnO2-Sb-CNT electrode is 1.15 times more effective in permeation flux than the Ti/SnO2-Sb electrode when combining electro-catalytic oxidation and nanofiltration for treating dye wastewater

  9. Multiwalled carbon nanotube modified screen-printed electrodes for the detection of p-aminophenol: Optimisation and application in alkaline phosphatase-based assays

    International Nuclear Information System (INIS)

    Carboxylated multiwalled carbon nanotubes (MWCNT-COOH) were used to modify the working electrode surface of different screen-printed electrodes. The effect of this modification on the electrodic characteristics (double layer capacitance, electroactive area and heterogeneous rate constants for the electron transfer) was evaluated and optimized for the cyclic voltammetric determination of p-aminophenol. The enzymatic hydrolysis of p-aminophenylphosphate was employed for the quantification of alkaline phosphatase, one of the most important label enzymes in immunoassays. Finally, ELISA assays were carried out to quantify pneumolysin using this enzymatic system. Results obtained indicated that low superficial densities of MWCNT-COOH (0.03-0.06 μg mm-2) yielded the same electrodic improvements but with better analytical properties

  10. Multiwalled carbon nanotube modified screen-printed electrodes for the detection of p-aminophenol: Optimisation and application in alkaline phosphatase-based assays

    Energy Technology Data Exchange (ETDEWEB)

    Lamas-Ardisana, Pedro Jose [Departamento de Quimica Fisica y Analitica, Universidad de Oviedo, 33006 Oviedo, Asturias (Spain); Queipo, Paula [Departamento de Fisica, Universidad de Oviedo, 33007 Oviedo, Asturias (Spain); Fanjul-Bolado, Pablo [Departamento de Quimica Fisica y Analitica, Universidad de Oviedo, 33006 Oviedo, Asturias (Spain); Costa-Garcia, Agustin [Departamento de Quimica Fisica y Analitica, Universidad de Oviedo, 33006 Oviedo, Asturias (Spain)], E-mail: costa@fq.uniovi.es

    2008-05-12

    Carboxylated multiwalled carbon nanotubes (MWCNT-COOH) were used to modify the working electrode surface of different screen-printed electrodes. The effect of this modification on the electrodic characteristics (double layer capacitance, electroactive area and heterogeneous rate constants for the electron transfer) was evaluated and optimized for the cyclic voltammetric determination of p-aminophenol. The enzymatic hydrolysis of p-aminophenylphosphate was employed for the quantification of alkaline phosphatase, one of the most important label enzymes in immunoassays. Finally, ELISA assays were carried out to quantify pneumolysin using this enzymatic system. Results obtained indicated that low superficial densities of MWCNT-COOH (0.03-0.06 {mu}g mm{sup -2}) yielded the same electrodic improvements but with better analytical properties.

  11. A Sensitive Simultaneous Determination of Adrenalin and Paracetamol on a Glassy Carbon Electrode Coated with a Film of Chitosan/Room Temperature Ionic Liquid/Single-Walled Carbon Nanotubes Nanocomposite%A Sensitive Simultaneous Determination of Adrenalin and Paracetamol on a Glassy Carbon Electrode Coated with a Film of Chitosan/Room Temperature Ionic Liquid/Single-Walled Carbon Nanotubes Nanocomposite

    Institute of Scientific and Technical Information of China (English)

    Babaei, Ali; Babazadeh, Mitra; Afrasiabi, Mohammad

    2011-01-01

    The present work demonstrates that simultaneous determination of adrenalin (AD) and paracetamol (PAR) can be performed on single-walled carbon nanotube/chitosan/ionic liquid modified glassy carbon electrode (SWCNT-CHIT-IL/GCE). The electro-oxidations of AD and PAR were investigated with cyclic voltammetry (CV), differential pulse voltammetry (DPV) and also chronoamperometry (CA) methods. DPV experiments showed that the oxidation peak currents of AD and PAR are proportional to the corresponding concentrations over the 1-580 μmol/L and 0.5-400 μmol/L ranges, respectively. The RSD at a concentration level of 15 μmol/L AD and 15 μmol/L PAR were 1.69% and 1.82%, respectively. Finally the modified electrode was used for simultaneous determination of AD and PAR in real samples with satisfactory results.

  12. Determination of cadmium(II) using glassy carbon electrodes modified with cupferron, β-naphthol, and multiwalled carbon nanotubes

    International Nuclear Information System (INIS)

    We report on a simple and reliable method for the determination of trace cadmium ion using a glassy carbon electrode (GCE) modified with cupferron, β-naphthol and MWCNTs. The operational mechanism consists of several steps: first, the ligand cupferron on the modified electrode reacts with Cd2+ ion to form a chelate compound. Next, this chelate is adsorbed by the carrier β-following the principle of organic co-precipitation. Finally, the coprecipitated complex is detected by the GCE. This scheme is interesting because it combines preconcentration and electrochemical detection. Two linear responses are obtained, one in the concentration range of 5.0 x 10-11 to 1.6 x 10-8 M, the other in the range of 1.6 x 10-8 to 1.42 x 10-6 M, with a lower detection limit of 1.6 x 10-11 M. This modified GCE does not suffer from significant interferences by Cu(II), Hg(II), Ag(I), Fe(III), Pb(II), Cr(III), Zn(II), NO3-, Cl-, SO42- ions and EDTA. The response of the electrode remained constant for at least 3 weeks of successive operation. The method presented here provides a new way for the simultaneous separation, enrichment, and electrochemical detection of trace cadmium ion. (author)

  13. ENOBIO - First tests of a dry electrophysiology electrode using carbon nanotubes

    CERN Document Server

    Ruffini, G; Farres, E; Watts, P C P; Mendoza, Eric; Silva, R; Grau, C; Marco-Pallares, J; Fuentemilla, L; Vanfleteren, J; De Moor, P; Van de Casteele, B; Ruffini, Giulio; Dunne, Stephen; Farres, Esteve; Watts, Paul C. P.; Mendoza, Ernest; Silva, Ravi; Grau, Carles; Marco-Pallares, Josep; Fuentemilla, Lluis; Vanfleteren, Jan; Moor, Piet De; Vandecasteele, Bjorn

    2006-01-01

    We describe the development and first tests of Enobio, a dry electrode sensor concept for biopotential applications. In the proposed electrodes, the tip of the electrode is covered with a forest of multi-walled CNTs that will be coated with Ag/AgCl to provide ionic-electronic transduction. The CNT brush-like structure is to penetrate the outer layers of the skin improving electrical contact as well as increae the contact surface area. In this paper, we report the results of the first tests of this concept -- immersion on saline solution and pig skin signal detection. These indicate performance on a par with state of the art research-oriented wet electrodes.

  14. Amperometric detection of nitrite in water samples by use of electrodes consisting of palladium-nanoparticle-functionalized multi-walled carbon nanotubes.

    Science.gov (United States)

    Thirumalraj, Balamurugan; Palanisamy, Selvakumar; Chen, Shen-Ming; Zhao, Duo-Han

    2016-09-15

    An amperometric determination of nitrite in different water samples was evaluated using palladium nanoparticles (PdNPs) decorated functionalized multiwalled carbon nanotubes (f-MWCNT) modified glassy carbon electrode. The f-MWCNT/PdNPs composite modified electrode was prepared by electrodeposition of PdNPs on the surface of f-MWCNT modified electrode. The parameters such as effect of number of cycles of PdNPs deposition, drop coated amount of f-MWCNT and effect of pH were optimized and discussed in detail. As-prepared f-MWCNT/PdNPs composite modified electrode exhibits excellent electrocatalytic activity towards the oxidation of nitrite compared to MWCNT, f-MWCNT and PdNPs modified electrodes. Amperometric i-t method was used to determine nitrite and the response of the nitrite on modified electrode was linear over the concentration from 0.05 to 2887.6μM. The response time of the sensor was estimated as 3s with the detection limit of 22nM. The fabricated f-MWCNT/PdNPs composite modified electrode shows its satisfactory practical ability in nitrite containing different water samples, which authenticate its potential ability for determination of nitrite. PMID:27344354

  15. Differential pulse voltammetric determination of methyl parathion based on multiwalled carbon nanotubes-poly(acrylamide) nanocomposite film modified electrode

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Yanbo [Department of Chemistry and Shanghai Key Laboratory of Green Chemistry and Chemical Process, East China Normal University, 3663 Zhongshan Road(N), Shanghai, 200062 (China); College of Biological, Chemical Sciences and Engineering, Jiaxing University, Jiaxing 314001 (China); Yu, Dajun; Yu, Yanyan [Department of Chemistry and Shanghai Key Laboratory of Green Chemistry and Chemical Process, East China Normal University, 3663 Zhongshan Road(N), Shanghai, 200062 (China); Zhou, Tianshu [Department of Environmental Science, East China Normal University, 3663 Zhongshan Road(N), Shanghai, 200062 (China); Shi, Guoyue, E-mail: gyshi@chem.ecnu.edu.cn [Department of Chemistry and Shanghai Key Laboratory of Green Chemistry and Chemical Process, East China Normal University, 3663 Zhongshan Road(N), Shanghai, 200062 (China)

    2012-05-30

    Highlights: Black-Right-Pointing-Pointer A sensitive electrochemical sensor for detecting methyl parathion in environmental samples. Black-Right-Pointing-Pointer The preparation, characterization and application of this novel MWCNTs-PAAM nanocomposite. Black-Right-Pointing-Pointer The MWCNTs-PAAM/GCE exhibited a high adsorption and strong affinity toward methyl parathion. Black-Right-Pointing-Pointer Wide linear range and low detection limit of the proposed method for detecting methyl parathion. - Abstract: A sensitive electrochemical differential pulse voltammetry method was developed for detecting methyl parathion based on multiwalled carbon nanotubes-poly(acrylamide) (MWCNTs-PAAM) nanocomposite film modified glassy carbon electrode. The novel MWCNTs-PAAM nanocomposite, containing high content of amide groups, was synthesized by PAAM polymerizing at the vinyl group functionalized MWCNTs surface using free radical polymerization. The MWCNTs-PAAM nanocomposite was characterized by Fourier transform infrared spectroscopy, thermal gravimetric analysis and scanning electron microscopy. Electrochemical behavior and interference studies of MWCNTs-PAAM/GCE for methyl parathion were investigated. The experimental results demonstrated that the MWCNTs-PAAM/GCE exhibited a high adsorption and strong affinity toward methyl parathion compared with some metal ions and nitroaromatic compounds, which exist in environmental samples. The adsorbed amount of methyl parathion on the MWCNTs-PAAM/GCE approached the equilibrium value upon 5 min adsorption time. A linear calibration curve for methyl parathion was obtained in the concentration range from 5.0 Multiplication-Sign 10{sup -9} to 1.0 Multiplication-Sign 10{sup -5} mol L{sup -1}, with a detection limit of 2.0 Multiplication-Sign 10{sup -9} mol L{sup -1}. The MWCNTs-PAAM/GCE was proved to be a suitable sensing tool for the fast, sensitive and selective determination of methyl parathion in environmental water samples.

  16. Preparation of electrochemically reduced graphene oxide/multi-wall carbon nanotubes hybrid film modified electrode, and its application to amperometric sensing of rutin

    Indian Academy of Sciences (India)

    Uling Yang; Gang Li; Meifang Hu; Lingbo Qu

    2014-07-01

    Through a facile electrochemical method, we prepared an electrochemically reduced graphene oxide (ERGO)/multi-wall carbon nanotubes (MWNTs) hybrid film modified glassy carbon electrode (GCE), and characterized it by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and x-ray diffraction (XRD) The experimental results demonstrated that ERGO-MWNTs/GCE exhibited excellent electrocatalytic activity toward rutin as evidenced by the significant enhancement of redox peak currents in comparison with a bare GCE, ERGO/GCE and MWNTs/GCE. This method has been applied for the direct determination of rutin in real samples with satisfactory results.

  17. Simultaneous determination of ascorbic acid, dopamine, and uric acid using a carbon paste electrode modified with multiwalled carbon nanotubes, ionic liquid, and palladium nanoparticles

    International Nuclear Information System (INIS)

    We describe the modification of a carbon paste electrode (CPE) with multiwalled carbon nanotubes (MWCNT) and an ionic liquid (IL). Electrochemical studies revealed an optimized composition of 60 % graphite, 20 % paraffin, 10 % MWCNT and 10 % IL. In a next step, the optimized CPE was modified with palladium nanoparticles (Pd-NPs) by applying a double-pulse electrochemical technique. The resulting electrode was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, cyclic voltammetry, and electrochemical impedance spectroscopy. It gives three sharp and well separated oxidation peaks for ascorbic acid (AA), dopamine (DA), and uric acid (UA), with peak separations of 180 and 200 mV for AA-DA and DA-UA, respectively. The sensor enables simultaneous determination of AA, DA and UA with linear responses from 0.6 to 112, 0.1 to 151, and 0.5 to 225 μM, respectively, and with 200, 30 and 150 nM detection limits (at an S/N of 3). The method was successfully applied to the determination of AA, DA, and UA in spiked samples of human serum and urine. (author)

  18. Electrohemical Properties of Carbon Nanotube Paste Electrodes Modified with Redox Cationic Dyes - doi: 10.4025/actascitechnol.v34i3.15250

    Directory of Open Access Journals (Sweden)

    Juliana Maria Ramos Antônio

    2012-05-01

    Full Text Available The present work describes the electrochemical behavior of cationic dyes (methylene blue and toluidine blue as electron mediators adsorbed in the multiwall carbon nanotubes paste in 0.5 KCl at pH 7.0 by using cyclic voltammetry. Based on midpoint potential [Em = (Eap + Ecp/2] and separation of cathodic and anodic peaks (ΔE, it was not observed interaction of different eletrolytes (LiCl, KCl, BaCl2, CaCl2, NaCl, NaNO3, Na2SO4 and NaClO4, with the cationic dyes by an ion exchange reaction and, as a consequence, absence of leaching of cationic dyes to the solution phase.  The kinetics of electron transfer on the surface electrode was not sufficiently fast showing a fairly resistence of carbon nanotube paste modified with the cationic dyes.  The midpoint potential and ΔE also were insentive to the pH range (4-8, confirming the protective effect of carbon nanotubes matrix, owing to strong interaction of between the latter and the nitrogen of nitrogen of cationic dyes with carbon nanotube matrix, minimizing the proton interaction under cationic dye. This result is very important for sensor/biosensor preparation, because the eletrooxidation behavior of the analyte will be only affected by its formal potencial shifting.  Carbon nanotubes proved to be an efficient solid matrix for the adsorption of mediator electron in comparison to the electrochemical behavior of free cationic dyes in solution phase.

  19. ELECTROCHEMICAL INVESTIGATION ON CARBON NANOTUBE FILM WITH DIFFERENT PRETREATMENTS

    Institute of Scientific and Technical Information of China (English)

    C.G. Hu; W.L. Wang; Y. Ma; W. Zhu

    2003-01-01

    Wide potential windows were found at carbon nanotube film electrodes in neutral solutions after being treated with nitric acid and mixed acid. Electrochemical reversibility was investigated at carbon nanotube films with different pretreatments for ferri/ferrocyanide and quinone /hydroquinone. Carbon nanotube film electrodes presented quasi-reversible electrochemical behavior for both electrolytes. In the range of scan rate, carbon nanotube film electrodes treated with acids showed heterogeneous electron-transfer properties, which was mainly controlled by its electron state density on the surface of the film. On the whole, the carbon nanotube electrode with nitric acid treatment presented the best electrochemical behaviors, so we chose it as an analytical electrode to determine the trace compound in dilute solution. The results demonstrated that this new electrode material exhibits superior performance characteristics for the detection of azide anion.

  20. Manganese oxide nanoflakes/multi-walled carbon nanotubes/chitosan nanocomposite modified glassy carbon electrode as a novel electrochemical sensor for chromium (III) detection

    International Nuclear Information System (INIS)

    Highlights: • CNTs/chitosan/GC electrode used as platform for electrodeposition of MnOx-nanoflakes. • Modified electrode has excellent catalytic activity for oxidation of Cr3+ at pH 3–7. • Detection limit and sensitivity of sensor for Cr3+ detection were 0.3 μM and 18.7 nA/μM. • Sensor has good stability and high selectivity in the presence of common interferences. • Sensor applied for the detection of Cr3+in real samples with satisfactory results. - Abstract: In this research a nanocomposite containing chitosan (Chit) and maltiwalled carbon nanotubes (MWCNTs) was applied as platform for immobilization of electrodeposited manganese oxide (MnOx) nanostructures. First, glassy carbon (GC) electrode modified with thin film of Chitosan/MWCNTs nanocomposite. Then MnOx nanostructures was electrodeposited onto Chitosan/MWCNTs modified GC electrode using combination of constant potential step (0.6 V) and cyclic voltammetry(0.3–0.6 V) techniques. The XRD patterns and scanning electron microscope images indicated immobilization of uniformly MnOx nanoflakes with high crystallite onto MWCNTs/Chit film. The modified electrode shows a well-defined redox couple for Mn2+/MnO2 system. Charge transfer coefficient (α), electron transfer rate constant (ks) and surface concentration (Γ) were 0.394, 3.44 s−1 and 3.3 × 10−11 mol cm−2, respectively. The modified electrode showed excellent electrocatalytic activity toward oxidation of chromium (III) at natural pH solutions. Cyclic voltammetry and hydrodynamic amperometery were applied as measuring techniques for chromium detection. Detection limit, sensitivity and linear concentration range of the sensor were, 0.3 (μM), 18.7 nAμ M−1 and 3 μM to 200 μM, respectively. Moreover, the sensor retained about 90% of its original response toward Cr(III) after storage three months in ambient condition. Furthermore, the sensor response toward different common interferences was negligible. Finally, the developed sensor

  1. Preparation of Ni(OH){sub 2}-graphene sheet-carbon nanotube composite as electrode material for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Y.F. [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); College of Environmental and Chemical Engineering, Heilongjiang University of Science and Technology, Harbin 150022 (China); Yuan, G.H., E-mail: ygh@hit.edu.cn [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Jiang, Z.H., E-mail: jiangzhaohua@hit.edu.cn [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Yao, Z.P. [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Yue, M. [Shenzhen BTR New Energy Materials INC., Shenzhen 528206 (China)

    2015-01-05

    Highlights: • CNT is introduced into graphene to prevent restacking by solvothermal reaction. • Ethanol as a low cost and green solvent is used in solvothermal reaction. • Ni(OH){sub 2} nanosheets were chemically precipitated into GS-CNT to increase the capacitance. - Abstract: Ni(OH){sub 2}-graphene sheet-carbon nanotube composite was prepared for supercapacitance materials through a simple two-step process involving solvothermal synthesis of graphene sheet-carbon nanotube composite in ethanol and chemical precipitation of Ni(OH){sub 2}. According to N{sub 2} adsorption/desorption analysis, the Brunauer–Emmett–Teller surface area of graphene sheet-carbon nanotube composite (109.07 m{sup 2} g{sup −1}) was larger than that of pure graphene sheets (32.06 m{sup 2} g{sup −1}), indicating that the added carbon nanotubes (15 wt.%) could prevent graphene sheets from restacking in the solvothermal reaction. The results of field emission scanning electron microscopy and transmission electron microscopy showed that Ni(OH){sub 2} nanosheets were uniformly loaded into the three-dimensional interconnected network of graphene sheet-carbon nanotube composite. The microstructure enhanced the rate capability and utilization of Ni(OH){sub 2}. The specific capacitance of Ni(OH){sub 2}-graphene sheet-carbon nanotube composite was 1170.38 F g{sup −1} at a current density of 0.2 A g{sup −1} in the 6 mol L{sup −1} KOH solution, higher than those provided by pure Ni(OH){sub 2} (953.67 Fg{sup −1}) and graphene sheets (178.25 F g{sup −1}). After 20 cycles at each current density (0.2, 0.4, 0.6, 0.8, 1.0 and 1.2 A g{sup −1}), the capacitance of Ni(OH){sub 2}-graphene sheet-carbon nanotube composite decreased 26.96% of initial capacitance compared to 74.52% for pure Ni(OH){sub 2}.

  2. Direct electron transfer and biosensing of glucose oxidase immobilized at multiwalled carbon nanotube-alumina-coated silica modified electrode

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Wei-Che; Huang, Jian-Lung; Tsai, Yu-Chen, E-mail: yctsai@dragon.nchu.edu.tw

    2012-05-01

    Investigations are reported regarding the direct electrochemical performance of glucose oxidase (GOD) immobilized on a film of multiwalled carbon nanotube-alumina-coated silica (MWCNT-ACS). The surface morphology of the GOD/MWCNT-ACS nanobiocomposite is characterized by scanning electron microscopy. In cyclic voltammetric response, the immobilized GOD displays a pair of well-defined redox peaks, with a formal potential (E Degree-Sign Prime ) of - 0.466 V versus Ag/AgCl in a 0.1 M phosphate buffer solution (pH 7.5) at a scan rate of 0.05 V s{sup -1}; also the electrochemical response indicates a surface-controlled electrode process. The dependence of formal potential on solution pH indicates that the direct electron transfer reaction of GOD is a reversible two-electron coupled with a two-proton electrochemical reaction process. The glucose biosensor based on the GOD/MWCNT-ACS nanobiocomposite shows a sensitivity of 0.127 A M{sup -1} cm{sup -2} and an apparent Michaelis-Menten constant of 0.5 mM. Furthermore, the prepared biosensor exhibits excellent anti-interference ability to the commonly co-existed uric acid and ascorbic acid. - Highlights: Black-Right-Pointing-Pointer A film composed of MWCNT-ACS was used for biosensor application. Black-Right-Pointing-Pointer High sensitivity and good selectivity were obtained for the detection of glucose. Black-Right-Pointing-Pointer This approach is potential for fabrication of mediator-free biosensor.

  3. Optimization of modified carbon paste electrode with multiwalled carbon nanotube/ionic liquid/cauliflower-like gold nanostructures for simultaneous determination of ascorbic acid, dopamine and uric acid

    Energy Technology Data Exchange (ETDEWEB)

    Afraz, Ahmadreza [Department of Physical Chemistry, Faculty of Chemistry, Bu-Ali Sina University, P.O. Box 65174, Hamedan (Iran, Islamic Republic of); Rafati, Amir Abbas, E-mail: aa_rafati@basu.ac.ir [Department of Physical Chemistry, Faculty of Chemistry, Bu-Ali Sina University, P.O. Box 65174, Hamedan (Iran, Islamic Republic of); Najafi, Mojgan [Department of Materials Engineering, Hamedan University of Technology (HUT), 65169 Hamedan (Iran, Islamic Republic of)

    2014-11-01

    We describe the modification of a carbon paste electrode (CPE) with multiwalled carbon nanotubes (MWCNTs) and an ionic liquid (IL). Electrochemical studies by using a D-optimal mixture design in Design-Expert software revealed an optimized composition of 60% graphite, 14.2% paraffin, 10.8% MWCNT and 15% IL. The optimal modified CPE shows good electrochemical properties that are well matched with model prediction parameters. In the next step, the optimized CPE was modified with gold nanostructures by applying a double-pulse electrochemical technique. The resulting electrode was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and electrochemical impedance spectroscopy. It gives three sharp and well-separated oxidation peaks for ascorbic acid (AA), dopamine (DA), and uric acid (UA). The sensor enables simultaneous determination of AA, DA and UA with linear responses from 0.3 to 285, 0.08 to 200, and 0.1 to 450 μM, respectively, and with 120, 30 and 30 nM detection limits (at an S/N of 3). The method was successfully applied to the determination of AA, DA, and UA in spiked samples of human serum and urine. - Highlights: • New method for simultaneous determination of AA, DA and UA was developed. • MWCNT/ionic liquid/cauliflower-like Au nanostructure was used for CPE modification. • Optimization of electrode composition was done by Design-Expert software. • The pH effect, peak separation mechanism and real samples was thoroughly studied.

  4. An amperometric hydrogen peroxide biosensor based on Co{sub 3}O{sub 4} nanoparticles and multiwalled carbon nanotube modified glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Kaçar, Ceren; Dalkiran, Berna; Erden, Pınar Esra, E-mail: erdenpe@gmail.com; Kiliç, Esma

    2014-08-30

    Highlights: • Hydrogen peroxide biosensor was constructed by combining the advantageous properties of MWCNTs and Co{sub 3}O{sub 4}. • Incorporating Co{sub 3}O{sub 4} nanoparticles into MWCNTs/gelatin film increased the electron transfer. • Co{sub 3}O{sub 4}/MWCNTs/gelatin/HRP/Nafion/GCE showed strong anti-interference ability. • Hydrogen peroxide was successfully determined in disinfector with an average recovery of 100.78 ± 0.89. - Abstract: In this work a new type of hydrogen peroxide biosensor was fabricated based on the immobilization of horseradish peroxidase (HRP) by cross-linking on a glassy carbon electrode (GCE) modified with Co{sub 3}O{sub 4} nanoparticles, multiwall carbon nanotubes (MWCNTs) and gelatin. The introduction of MWCNTs and Co{sub 3}O{sub 4} nanoparticles not only enhanced the surface area of the modified electrode for enzyme immobilization but also facilitated the electron transfer rate, resulting in a high sensitivity of the biosensor. The fabrication process of the sensing surface was characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Amperometric detection of hydrogen peroxide was investigated by holding the modified electrode at −0.30 V (vs. Ag/AgCl). The biosensor showed optimum response within 5 s at pH 7.0. The optimized biosensor showed linear response range of 7.4 × 10{sup −7}–1.9 × 10{sup −5} M with a detection limit of 7.4 × 10{sup −7}. The applicability of the purposed biosensor was tested by detecting hydrogen peroxide in disinfector samples. The average recovery was calculated as 100.78 ± 0.89.

  5. Optimization of modified carbon paste electrode with multiwalled carbon nanotube/ionic liquid/cauliflower-like gold nanostructures for simultaneous determination of ascorbic acid, dopamine and uric acid

    International Nuclear Information System (INIS)

    We describe the modification of a carbon paste electrode (CPE) with multiwalled carbon nanotubes (MWCNTs) and an ionic liquid (IL). Electrochemical studies by using a D-optimal mixture design in Design-Expert software revealed an optimized composition of 60% graphite, 14.2% paraffin, 10.8% MWCNT and 15% IL. The optimal modified CPE shows good electrochemical properties that are well matched with model prediction parameters. In the next step, the optimized CPE was modified with gold nanostructures by applying a double-pulse electrochemical technique. The resulting electrode was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and electrochemical impedance spectroscopy. It gives three sharp and well-separated oxidation peaks for ascorbic acid (AA), dopamine (DA), and uric acid (UA). The sensor enables simultaneous determination of AA, DA and UA with linear responses from 0.3 to 285, 0.08 to 200, and 0.1 to 450 μM, respectively, and with 120, 30 and 30 nM detection limits (at an S/N of 3). The method was successfully applied to the determination of AA, DA, and UA in spiked samples of human serum and urine. - Highlights: • New method for simultaneous determination of AA, DA and UA was developed. • MWCNT/ionic liquid/cauliflower-like Au nanostructure was used for CPE modification. • Optimization of electrode composition was done by Design-Expert software. • The pH effect, peak separation mechanism and real samples was thoroughly studied

  6. Applications of Carbon Nanotubes

    Science.gov (United States)

    Ajayan, Pulickel M.; Zhou, Otto Z.

    Carbon nanotubes have attracted the fancy of many scientists worldwide. The small dimensions, strength and the remarkable physical properties of these structures make them a very unique material with a whole range of promising applications. In this review we describe some of the important materials science applications of carbon nanotubes. Specifically we discuss the electronic and electrochemical applications of nanotubes, nanotubes as mechanical reinforcements in high performance composites, nanotube-based field emitters, and their use as nanoprobes in metrology and biological and chemical investigations, and as templates for the creation of other nanostructures. Electronic properties and device applications of nanotubes are treated elsewhere in the book. The challenges that ensue in realizing some of these applications are also discussed from the point of view of manufacturing, processing, and cost considerations.

  7. Organic modification of carbon nanotubes

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The organic modification of carbon nanotubes is a novel research field being developed recently. In this article, the history and newest progress of organic modification of carbon nanotubes are reviewed from two aspects:organic covalent modification and organic noncovalent modification of carbon nanotubes. The preparation and properties of organic modified carbon nanotubes are discussed in detail. In addition, the prospective development of organic modification of carbon nanotubes is suggested.

  8. OPPORTUNITIES OF BIOMEDICAL USE OF CARBON NANOTUBES

    Directory of Open Access Journals (Sweden)

    I. V. Mitrofanova

    2015-12-01

    Full Text Available Nanomaterials  –  materials,  whouse  structure  elements  has  proportions  doesn’t  exceed  100  nm.  In superdispersed state matter acquire new properties. In the last decade, carbon nanotubes become the most popular nanomaterials, that cause attention of representatives of various scientific field. The сarbon nanotubes offer new opportunities for biological and medical applications: imaging at the molecular, cellular and tissue levels, biosensors and electrodes based on carbon nanotubes, target delivery of various substances, radiation and photothermal therapy. The most promising of carbon nanotubes in the context of biomedical applications is their ability to penetrate the various tissues of the body and carry large doses of agents, providing diagnostic and therapeutic effects. Functionalized nanotubes are biodegradable. Other current direction of using carbon nanotubes in medicine and biology is to visualize objects on the molecular, cellular and tissue level. Associated with carbon nanotubes contrasting substances improve the visualization of cells and tissues, which can detected new patterns of development of the pathological process. Due to the vagueness of the question of biocompatibility and cytotoxicity of carbon nanotubes possibility of their practical application is hampered. Before the introduction of carbon nanotubes into practical health care is necessary to provide all the possible consequences of using nanotubes. High rates of properties and development of new nanostructures based on carbon nanotubes in the near future will lead to new advances related to the application and development of new parameters that will determine their properties and effects. In these review attention is paid to the structure, physico-chemical properties of nanotubes, their functionalization, pharmacokinetics and pharmacodynamics and all aspects of using of carbon nanotubes.

  9. Carbon paste electrode incorporating multi-walled carbon nanotube/ferrocene as a sensor for the electroanalytical determination of -acetyl--cysteine in the presence of tryptophan

    Indian Academy of Sciences (India)

    Jahan Bakhsh Raoof; Fereshteh Chekin; Reza Ojani; Saeideh Barari

    2013-03-01

    The preparation and electrochemical performance of the carbon nanotube paste electrode modified with ferrocene (FCMCNPE) was investigated for electrocatalytic behaviour toward oxidation of -acetyl--cysteine (NAC) in the presence of tryptophan (Trp) using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The results showed an efficient electrocatalytic activity of FCMCNPE toward oxidation of NAC and Trp, as the electrooxidation of NAC and Trp together gave two well-defined anodic peaks, revealing the applicability of this modified electrode for simultaneous voltammetric detection of mentioned compounds in the same solution. The values of catalytic rate constant () and the apparent diffusion coefficient (Dapp) were also calculated using chronoamperometry. The DPV method was applied as a sensitive method for the quantitative detection of trace amounts of NAC and Trp. A linear dynamic range from 1.0 to 18.0 M for NAC and 2.0 to 150.0 M for Trp was obtained using DPV method in pH 7.00 buffered solution and the detection limit (3) was determined as 0.49 M and 0.54 M for NAC and Trp, respectively. The proposed method was also applied for analysis of NAC tablet, investigating the applicability of the proposed voltammetric method for determination of NAC in real sample.

  10. Electrocatalytic determination of L-cysteine using a modified carbon nanotube paste electrode: Application to the analysis of some real samples

    Institute of Scientific and Technical Information of China (English)

    Malihe Ahmadipour; Mohammad Ali Taher; Hadi Beitollahi; Rahman Hosseinzadeh

    2012-01-01

    The electrooxidation of L-cysteine (L-Cys) was studied using a benzoylferrocene (BF) modified multi-wall carbon nanotube paste electrode (BFCNPE) using cyclic voltammetry (CV),square wave voltammetry (SWV) and chronoamperometry (CHA).Under optimum pH in CV the oxidation of L-Cys occurs at a potential about 215 mV less positive than that at the surface of unmodified carbon paste electrode.The catalytic oxidation peak currents were dependent on the L-Cys concentration and a linearcalibration curve was obtained in the range 0.7-350.0 μmol/L of L-Cys with SWV method.The detection limit (3σ) was determined as 0.1 μmolL.This method was also used for the determination of L-Cys in some real samples.

  11. Non-enzymatic sensing of uric acid using a carbon nanotube ionic-liquid paste electrode modified with poly(β-cyclodextrin)

    International Nuclear Information System (INIS)

    We describe a nonenzymatic electrochemical sensor for uric acid. It is based on a carbon nanotube ionic-liquid paste electrode modified with poly(β-cyclodextrin) that was prepared in-situ by electropolymerization. The functionalized multi-walled carbon nanotubes and the surface morphology of the modified electrodes were characterized by transmission electronic microscopy and scanning electron microscopy. The electrochemical response of uric acid was studied by cyclic voltammetry and linear sweep voltammetry. The effects of scan rate, pH value, electropolymerization cycles and accumulation time were also studied. Under optimized experimental conditions and at a working voltage of 500 mV vs. Ag/AgCl (3 M KCl), response to uric acid is linear in the 0.6 to 400 μΜ and in the 0.4 to 1 mΜ concentration ranges, and the detection limit is 0.3 μΜ (at an S/N of 3). The electrode was successfully applied to the detection of uric acid in (spiked) human urine samples. (author)

  12. Highly sensitive amperometric sensor for micromolar detection of trichloroacetic acid based on multiwalled carbon nanotubes and Fe(II)–phtalocyanine modified glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Kurd, Masoumeh [Department of Chemistry, University of Kurdistan, P. O. Box 416, Sanandaj (Iran, Islamic Republic of); Salimi, Abdollah, E-mail: absalimi@uok.ac.ir [Department of Chemistry, University of Kurdistan, P. O. Box 416, Sanandaj (Iran, Islamic Republic of); Research Center for Nanotechnology, University of Kurdistan, P. O. Box 416, Sanandaj (Iran, Islamic Republic of); Hallaj, Rahman [Department of Chemistry, University of Kurdistan, P. O. Box 416, Sanandaj (Iran, Islamic Republic of)

    2013-04-01

    A highly sensitive electrochemical sensor for the detection of trichloroacetic acid (TCA) is developed by subsequent immobilization of phthalocyanine (Pc) and Fe(II) onto multiwalled carbon nanotubes (MWCNTs) modified glassy carbon (GC) electrode. The GC/MWCNTs/Pc/Fe(II) electrode showed a pair of well-defined and nearly reversible redox couple correspondent to (Fe(III)Pc/Fe(II)Pc) with surface-confined characteristics. The surface coverage (Γ) and heterogeneous electron transfer rate constant (k{sub s}) of immobilized Fe(II)–Pc were calculated as 1.26 × 10{sup −10} mol cm{sup −2} and 28.13 s{sup −1}, respectively. Excellent electrocatalytic activity of the proposed GC/MWCNTs/Pc/Fe(II) system toward TCA reduction has been indicated and the three consequent irreversible peaks for electroreduction of CCl{sub 3}COOH to CH{sub 3}COOH have been clearly seen. The observed chronoamperometric currents are linearly increased with the concentration of TCA at concentration range up to 20 mM. Detection limit and sensitivity of the modified electrode were 2.0 μM and 0.10 μA μM{sup −1} cm{sup −2}, respectively. The applicability of the sensor for TCA detection in real samples was tested. The obtained results suggest that the proposed system can serve as a promising electrochemical platform for TCA detection. Highlights: ► Phthalocyanine (PC) and Fe(II) immobilized onto MWCNTs modified GC electrode. ► A pair of well-defined redox couple correspondent to (Fe(III)Pc/Fe(II)Pc) observed. ► Modified electrode shows excellent catalytic activity to electroreduction of CCl{sub 3}COOH. ► Amperometry and cyclic voltammetry techniques were used for detection of CCl{sub 3}COOH. ► Detection limit and sensitivity were 2.0 μM and 0.10 μA μM{sup −1} cm{sup −2}, respectively.

  13. Empirical study of unipolar and bipolar configurations using high resolution single multi-walled carbon nanotube electrodes for electrophysiological probing of electrically excitable cells

    International Nuclear Information System (INIS)

    Identifying the neurophysiological basis underlying learning and memory in the mammalian central nervous system requires the development of biocompatible, high resolution, low electrode impedance electrophysiological probes; however, physically, electrode impedance will always be finite and, at times, large. Herein, we demonstrate through experiments performed on frog sartorius muscle that single multi-walled carbon nanotube electrode (sMWNT electrode) geometry and placement are two degrees of freedom that can improve biocompatibility of the probe and counteract the detrimental effects of MWNT/electrolyte interface impedance on the stimulation efficiency and signal-to-noise ratio (SNR). We show that high aspect ratio dependent electric field enhancement at the MWNT tip can boost stimulation efficiency. Derivation of the sMWNT electrode's electrical equivalent indicates that, at low stimulus voltage regimes below 1 V, current conduction is mediated by charge fluctuation in the double layer obviating electrolysis of water, which is potentially toxic to pH sensitive biological tissue. Despite the accompanying increase in electrode impedance, a pair of closely spaced sMWNT electrodes in a two probe (bipolar) configuration maintains biocompatibility and enhances stimulation efficiency and SNR compared to the single probe (unipolar) configuration. For stimulus voltages below 1 V, the electrical equivalent verifies that current conduction in the two probe configuration still proceeds via charge fluctuation in the double layer. As an extracellular stimulation electrode, the two sMWNT electrodes comprise a current dipole that concentrates the electric field and the current density in a smaller region of sartorius; consequently, the bipolar configuration can elicit muscle fiber twitching at low voltages that preclude electrolysis of water. When recording field potentials, the bipolar configuration subtracts the potential between two points allowing for the detection of

  14. Direct electrochemistry with enhanced electrocatalytic activity of hemoglobin in hybrid modified electrodes composed of graphene and multi-walled carbon nanotubes

    International Nuclear Information System (INIS)

    Graphical abstract: -- Highlights: •A graphene and multi-walled carbon nanotubes nanocomposite was prepared. •Hemoglobin and nanocomposite modified carbon ionic liquid electrode was fabricated. •Direct electrochemistry of hemoglobin was realized on the modified electrode. •Bioelectrocatalysis towards the reduction of different substrates was enhanced. -- Abstract: A graphene (GR) and multi-walled carbon nanotubes (MWCNT) hybrid was prepared and modified on a 1-hexylpyridinium hexafluorophosphate based carbon ionic liquid electrode (CILE). Hemoglobin (Hb) was immobilized on GR-MWCNT/CILE surface with Nafion as the film forming material and the modified electrode was denoted as Nafion/Hb-GR-MWCNT/CILE. Spectroscopic results revealed that Hb molecules retained its native structure in the GR-MWCNT hybird. Electrochemical behaviors of Hb were carefully investigated by cyclic voltammetry with a pair of well-defined redox peaks obtained, which indicated that direct electron transfer of Hb was realized in the hybrid modified electrode. The result could be attributed to the synergistic effects of GR-MWCNT hybrid with enlarged surface area and improved conductivity through the formation of a three-dimensional network. Electrochemical parameters of the immobilized Hb on the electrode surface were further calculated with the results of the electron transfer number (n) as 1.03, the charge transfer coefficient (a) as 0.58 and the electron-transfer rate constant (ks) as 0.97 s−1. The Hb modified electrode showed good electrocatalytic ability toward the reduction of different substrates such as trichloroacetic acid in the concentration range from 0.05 to 38.0 mmol L−1 with a detection limit of 0.0153 mmol L−1 (3σ), H2O2 in the concentration range from 0.1 to 516.0 mmol L−1 with a detection limit of 34.9 nmol/L (3σ) and NaNO2 in the concentration range from 0.5 to 650.0 mmol L−1 with a detection limit of 0.282 μmol L−1 (3σ). So the proposed electrode had the

  15. Direct electrochemistry with enhanced electrocatalytic activity of hemoglobin in hybrid modified electrodes composed of graphene and multi-walled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Wei, E-mail: swyy26@hotmail.com [College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158 China (China); College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Cao, Lili; Deng, Ying; Gong, Shixing [College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Shi, Fan; Li, Gaonan; Sun, Zhenfan [College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158 China (China)

    2013-06-05

    Graphical abstract: -- Highlights: •A graphene and multi-walled carbon nanotubes nanocomposite was prepared. •Hemoglobin and nanocomposite modified carbon ionic liquid electrode was fabricated. •Direct electrochemistry of hemoglobin was realized on the modified electrode. •Bioelectrocatalysis towards the reduction of different substrates was enhanced. -- Abstract: A graphene (GR) and multi-walled carbon nanotubes (MWCNT) hybrid was prepared and modified on a 1-hexylpyridinium hexafluorophosphate based carbon ionic liquid electrode (CILE). Hemoglobin (Hb) was immobilized on GR-MWCNT/CILE surface with Nafion as the film forming material and the modified electrode was denoted as Nafion/Hb-GR-MWCNT/CILE. Spectroscopic results revealed that Hb molecules retained its native structure in the GR-MWCNT hybird. Electrochemical behaviors of Hb were carefully investigated by cyclic voltammetry with a pair of well-defined redox peaks obtained, which indicated that direct electron transfer of Hb was realized in the hybrid modified electrode. The result could be attributed to the synergistic effects of GR-MWCNT hybrid with enlarged surface area and improved conductivity through the formation of a three-dimensional network. Electrochemical parameters of the immobilized Hb on the electrode surface were further calculated with the results of the electron transfer number (n) as 1.03, the charge transfer coefficient (a) as 0.58 and the electron-transfer rate constant (k{sub s}) as 0.97 s{sup −1}. The Hb modified electrode showed good electrocatalytic ability toward the reduction of different substrates such as trichloroacetic acid in the concentration range from 0.05 to 38.0 mmol L{sup −1} with a detection limit of 0.0153 mmol L{sup −1} (3σ), H{sub 2}O{sub 2} in the concentration range from 0.1 to 516.0 mmol L{sup −1} with a detection limit of 34.9 nmol/L (3σ) and NaNO{sub 2} in the concentration range from 0.5 to 650.0 mmol L{sup −1} with a detection limit of 0

  16. Emerging transparent electrodes based on thin films of carbon nanotubes, graphene, and metallic nanostructures.

    Science.gov (United States)

    Hecht, David S; Hu, Liangbing; Irvin, Glen

    2011-04-01

    Transparent electrodes are a necessary component in many modern devices such as touch screens, LCDs, OLEDs, and solar cells, all of which are growing in demand. Traditionally, this role has been well served by doped metal oxides, the most common of which is indium tin oxide, or ITO. Recently, advances in nano-materials research have opened the door for other transparent conductive materials, each with unique properties. These include CNTs, graphene, metal nanowires, and printable metal grids. This review will explore the materials properties of transparent conductors, covering traditional metal oxides and conductive polymers initially, but with a focus on current developments in nano-material coatings. Electronic, optical, and mechanical properties of each material will be discussed, as well as suitability for various applications. PMID:21322065

  17. Carbon nanotube macroelectronics

    Science.gov (United States)

    Zhang, Jialu

    In this dissertation, I discuss the application of carbon nanotubes in macroelectronis. Due to the extraordinary electrical properties such as high intrinsic carrier mobility and current-carrying capacity, single wall carbon nanotubes are very desirable for thin-film transistor (TFT) applications such as flat panel display, transparent electronics, as well as flexible and stretchable electronics. Compared with other popular channel material for TFTs, namely amorphous silicon, polycrystalline silicon and organic materials, nanotube thin-films have the advantages of low-temperature processing compatibility, transparency, and flexibility, as well as high device performance. In order to demonstrate scalable, practical carbon nanotube macroelectroncis, I have developed a platform to fabricate high-density, uniform separated nanotube based thin-film transistors. In addition, many other essential analysis as well as technology components, such as nanotube film density control, purity and diameter dependent semiconducting nanotube electrical performance study, air-stable n-type transistor fabrication, and CMOS integration platform have also been demonstrated. On the basis of the above achievement, I have further demonstrated various kinds of applications including AMOLED display electronics, PMOS and CMOS logic circuits, flexible and transparent electronics. The dissertation is structured as follows. First, chapter 1 gives a brief introduction to the electronic properties of carbon nanotubes, which serves as the background knowledge for the following chapters. In chapter 2, I will present our approach of fabricating wafer-scale uniform semiconducting carbon nanotube thin-film transistors and demonstrate their application in display electronics and logic circuits. Following that, more detailed information about carbon nanotube thin-film transistor based active matrix organic light-emitting diode (AMOLED) displays is discussed in chapter 3. And in chapter 4, a technology to

  18. Electrochemical sandwich immunoassay for the peptide hormone prolactin using an electrode modified with graphene, single walled carbon nanotubes and antibody-coated gold nanoparticles

    International Nuclear Information System (INIS)

    We describe a new kind of electrochemical immunoassay for the peptide hormone prolactin. A glassy carbon electrode (GCE) was modified with a hybrid material consisting of graphene, single walled carbon nanotubes and gold nanoparticles (AuNPs) in a chitosan (CS) matrix. The graphene and the single wall carbon nanotubes were first placed on the GCE, and the AuNPs were then electrodeposited on the surface by cyclic voltammetry. This structure results in a comparably large surface for immobilization of the capturing antibody (Ab1). The modified electrode was used in a standard sandwich-type of immunoassay. The secondary antibody (Ab2) consisted of AuNPs with immobilized Ab2 and modified with biotinylated DNA as signal tags. Finally, alkaline phosphatase was bound to the biotinylated DNA-AuNPs-Ab2 conjugate via streptavidin chemistry. The enzyme catalyzes the hydrolysis of the α-naphthyl phosphate to form α-naphthol which is highly electroactive at an operating voltage as low as 180 mV (vs. Ag/AgCl). The resulting immunoassay exhibits high sensitivity, wide linear range (50 to 3200 pg∙mL-1), low detection limit (47 pg∙mL-1), acceptable selectivity and reproducibility. The assay provides a pragmatic platform for signal amplification and has a great potential for the sensitive determination of antigens other than prolactine. (author)

  19. Fabrication and Electrochemical Properties of Carbon Nanotube-based Composite Electrodes for Electrochemical Capacitor Applications

    Institute of Scientific and Technical Information of China (English)

    Kwang; Bum; Kim

    2007-01-01

    1 Results Electrochemical capacitors (ECs) are expected to be used in hybrid electric vehicles in combination with batteries or fuel cells because of their higher power density than batteries. ECs using electrical double layer capacitance of carbon based materials and pseudocapacitance of transition metal oxides are called electrochemical double layer capacitors (EDLC) and supercapacitors (or pseudocapacitor), respectively. Transition metal oxides are considered the best candidates for high energy dens...

  20. Electrical Transport in Carbon Nanotubes and Graphene

    OpenAIRE

    Liu, Gang

    2010-01-01

    This thesis summarizes our work in the past few years in the field of transport studies of carbon nanotubes and graphene. The first half of the thesis focuses on carbon nanotube (CNT) Josephson junctions (JJ) formed by coupling CNTs to superconducting electrodes. They exhibited Fabry Perot resonance patterns, enhanced differential conductance peaks, multiple Andreev reflection peaks, gate-tunable supercurrent transistor behaviors, hysteretic current-voltage line shape and "superconductor-insu...

  1. Carbon Nanotube Paper-Based Electroanalytical Devices

    OpenAIRE

    Youngmi Koo; Vesselin N. Shanov; Yeoheung Yun

    2016-01-01

    Here, we report on carbon nanotube paper-based electroanalytical devices. A highly aligned-carbon nanotube (HA-CNT) array, grown using chemical vapor deposition (CVD), was processed to form bi-layered paper with an integrated cellulose-based Origami-chip as the electroanalytical device. We used an inverse-ordered fabrication method from a thick carbon nanotube (CNT) sheet to a thin CNT sheet. A 200-layered HA-CNT sheet and a 100-layered HA-CNT sheet are explored as a working electrode. The de...

  2. Facile synthesis of β-lactoglobulin-functionalized multi-wall carbon nanotubes and gold nanoparticles on glassy carbon electrode for electrochemical sensing.

    Science.gov (United States)

    Du, Xin; Miao, Zhiying; Zhang, Di; Fang, Yuxin; Ma, Min; Chen, Qiang

    2014-12-15

    A facile approach was developed for the preparation of nanocomposite based on β-lactoglobulin (BLG)-functionalized multi-wall carbon nanotubes (MWCNTs) and gold nanoparticles (GNPs) for the first time. Owing to the amphipathic nature, BLG can be adopted onto the surface of MWCNTs to form BLG-MWCNTs with uniform dispersion in water. Taking advantage of sulfhydryl groups on BLG-MWCNTs, GNPs were decorated on the BLG-MWCNTs-modified glassy carbon electrode (GCE) by electrodeposition. The nanocomposite was characterized by transmission electron microscopy, scanning electron microscopy and X-ray spectroscopy analysis. Cyclic voltammetry and chronoamperometric method were used to evaluate the electrocatalytic ability of the nanocomposite. Furthermore, a glucose biosensor was developed based on the immobilization of glucose oxidase with cross-linking in the matrix of bovine serum albumin (BSA) on the nanocomposite modified GCE. The resulting biosensor exhibited high sensitivity (3.98 μA mM(-1)), wider linear range (0.025-5.5 mM), low detection limit (1.1 μM at the signal-to-noise ratio of 3) and fast response time (within 7s) for glucose detection. PMID:24984286

  3. Biosensor for bisphenol A leaching from baby bottles using a glassy carbon electrode modified with DNA and single walled carbon nanotubes

    International Nuclear Information System (INIS)

    We have developed a biosensor for highly sensitive and selective determination of the endocrinic disruptor bisphenol A (BPA). It is based on glassy carbon electrode modified with calf thymus DNA and a composite prepared from single walled carbon nanotubes (SWNT) and Nafion. The interaction between BPA and DNA was studied by voltammetry. The binding constant was determined to be 3.55 × 103 M−1, and the binding site has a length of 4.3 base pairs. These electrochemical studies provide further information for a better understanding of the toxicity and carcinogenicity of BPA. Under optimal conditions, the biosensor displays a linear electrochemical response to BPA in the 10 nM to 20 μM concentration range, with a detection limit as low as 5.0 nM (at an S/N of 3). The method was successfully applied to the quantification of BPA in leachates from plastic baby bottles. Recoveries range from 94.0 % to 106.0 % which underpins the excellent performance of this SWNT-based DNA sensor. (author)

  4. High Sensitivity Electrochemical Cholesterol Sensor Utilizing a Vertically Aligned Carbon Nanotube Electrode with Electropolymerized Enzyme Immobilization

    Directory of Open Access Journals (Sweden)

    Ditsayut Phokharatkul

    2009-10-01

    Full Text Available In this report, a new cholesterol sensor is developed based on a vertically aligned CNT electrode with two-step electrochemical polymerized enzyme immobilization. Vertically aligned CNTs are selectively grown on a 1 mm2 window of gold coated SiO2/Si substrate by thermal chemical vapor deposition (CVD with gravity effect and water-assisted etching. CNTs are then simultaneously functionalized and enzyme immobilized by electrochemical polymerization of polyaniline and cholesterol enzymes. Subsequently, ineffective enzymes are removed and new enzymes are electrochemically recharged. Scanning electron microscopic characterization indicates polymer-enzyme nanoparticle coating on CNT surface. Cyclic voltammogram (CV measurements in cholesterol solution show the oxidation and reduction peaks centered around 450 and −220 mV, respectively. An approximately linear relationship between the cholesterol concentration and the response current could be observed in the concentration range of 50–300 mg/dl with a sensitivity of approximately 0.22 μA/mg·dl−1, which is considerably higher compared to previously reported CNT bioprobe. In addition, good specificity toward glucose, uric acid acetaminophen and ascorbic acid have been obtained. Moreover, sensors have satisfactory stability, repeatability and life time. Therefore, the electropolymerized CNT bioprobe is promising for cholesterol detection in normal cholesterol concentration in human blood.

  5. Determination of trace heavy metals in herbs by sequential injection analysis-anodic stripping voltammetry using screen-printed carbon nanotubes electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Injang, Uthaitip; Noyrod, Peeyanun [Sensor Research Unit, Department of Chemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Siangproh, Weena [Department of Chemistry, Faculty of Science, Srinakharinwirot University, Sukumvit 23 Rd., Wattana, Bangkok 10110 (Thailand); Dungchai, Wijitar [Sensor Research Unit, Department of Chemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Motomizu, Shoji [Department of Chemistry, Faculty of Science, Okayama University, 3-1-1 Tsushimanaka, Okayama 700-8530 (Japan); Chailapakul, Orawon, E-mail: corawon@chula.ac.th [Sensor Research Unit, Department of Chemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Center for Petroleum, Petrochemicals and Advanced Materials, Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand)

    2010-05-23

    A method for the simultaneous determination of Pb(II), Cd(II), and Zn(II) at low {mu}g L{sup -1} concentration levels by sequential injection analysis-anodic stripping voltammetry (SIA-ASV) using screen-printed carbon nanotubes electrodes (SPCNTE) was developed. A bismuth film was prepared by in situ plating of bismuth on the screen-printed carbon nanotubes electrode. Operational parameters such as ratio of carbon nanotubes to carbon ink, bismuth concentration, deposition time and flow rate during preconcentration step were optimized. Under the optimal conditions, the linear ranges were found to be 2-100 {mu}g L{sup -1} for Pb(II) and Cd(II), and 12-100 {mu}g L{sup -1} for Zn(II). The limits of detection (S{sub bl}/S = 3) were 0.2 {mu}g L{sup -1} for Pb(II), 0.8 {mu}g L{sup -1} for Cd(II) and 11 {mu}g L{sup -1} for Zn(II). The measurement frequency was found to be 10-15 stripping cycle h{sup -1}. The present method offers high sensitivity and high throughput for on-line monitoring of trace heavy metals. The practical utility of our method was also demonstrated with the determination of Pb(II), Cd(II), and Zn(II) by spiking procedure in herb samples. Our methodology produced results that were correlated with ICP-AES data. Therefore, we propose a method that can be used for the automatic and sensitive evaluation of heavy metals contaminated in herb items.

  6. Supercapacitor electrodes by direct growth of multi-walled carbon nanotubes on Al: a study of performance versus layer growth evolution

    International Nuclear Information System (INIS)

    Supercapacitor electrodes were fabricated by direct growth of multi-walled carbon nanotubes (CNTs) on Al current collectors via a chemical vapor deposition process in the presence of a spin-coated Co-Mo catalyst. A detailed study of the dependence of the CNT layer structure and thickness on growth time set the basis for the assessment of supercapacitors assembled with the CNTs/Al electrodes. As the main features of the layer growth evolution, an increase in the population of finer CNTs and a shift from a random entanglement to a rough vertical alignment of nanotubes were noted with proceeding growth. The growth time influence on the performance of supercapacitors was in fact apparent. Particularly, the specific capacitance of CNTs/Al electrodes in 0.5 M K2SO4 aqueous electrolyte increased from 35 to 80 F g−1 as the CNT layer thickness varied from 20 to 60 μm, with a concurrent loss in rate capability (knee frequency from 1 kHz to 60 Hz). The latter was excellent in general, arguably due to both a fast ion transport through the interconnected CNT network and a negligible contribution of the active layer/current collector contact to the equivalent series resistance (0.15–0.22 mΩ g), a distinct advantage of the direct growth fabrication method. Overall, a relatively simple process of direct growth of CNTs on Al foils is shown to be an effective method to fabricate supercapacitor electrodes, notably in the absence of special measures and processing steps finalized to a tight control of nanotubes growth and organization

  7. Conducting carbonized polyaniline nanotubes

    Science.gov (United States)

    Mentus, Slavko; Ćirić-Marjanović, Gordana; Trchová, Miroslava; Stejskal, Jaroslav

    2009-06-01

    Conducting nitrogen-containing carbon nanotubes were synthesized by the carbonization of self-assembled polyaniline nanotubes protonated with sulfuric acid. Carbonization was carried out in a nitrogen atmosphere at a heating rate of 10 °C min-1 up to a maximum temperature of 800 °C. The carbonized polyaniline nanotubes which have a typical outer diameter of 100-260 nm, with an inner diameter of 20-170 nm and a length extending from 0.5 to 0.8 µm, accompanied with very thin nanotubes with outer diameters of 8-14 nm, inner diameters 3.0-4.5 nm and length extending from 0.3 to 1.0 µm, were observed by scanning and transmission electron microscopies. Elemental analysis showed 9 wt% of nitrogen in the carbonized product. Conductivity of the nanotubular PANI precursor, amounting to 0.04 S cm-1, increased to 0.7 S cm-1 upon carbonization. Molecular structure of carbonized polyaniline nanotubes has been analyzed by FTIR and Raman spectroscopies, and their paramagnetic characteristics were compared with the starting PANI nanotubes by EPR spectroscopy.

  8. Conducting carbonized polyaniline nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Mentus, Slavko; Ciric-Marjanovic, Gordana [Faculty of Physical Chemistry, University of Belgrade, Studentski trg 12-16, 11158 Belgrade (Serbia); Trchova, Miroslava; Stejskal, Jaroslav [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovsky Square 2, 162 06 Prague 6 (Czech Republic)], E-mail: gordana@ffh.bg.ac.rs

    2009-06-17

    Conducting nitrogen-containing carbon nanotubes were synthesized by the carbonization of self-assembled polyaniline nanotubes protonated with sulfuric acid. Carbonization was carried out in a nitrogen atmosphere at a heating rate of 10 deg. C min{sup -1} up to a maximum temperature of 800 deg. C. The carbonized polyaniline nanotubes which have a typical outer diameter of 100-260 nm, with an inner diameter of 20-170 nm and a length extending from 0.5 to 0.8 {mu}m, accompanied with very thin nanotubes with outer diameters of 8-14 nm, inner diameters 3.0-4.5 nm and length extending from 0.3 to 1.0 {mu}m, were observed by scanning and transmission electron microscopies. Elemental analysis showed 9 wt% of nitrogen in the carbonized product. Conductivity of the nanotubular PANI precursor, amounting to 0.04 S cm{sup -1}, increased to 0.7 S cm{sup -1} upon carbonization. Molecular structure of carbonized polyaniline nanotubes has been analyzed by FTIR and Raman spectroscopies, and their paramagnetic characteristics were compared with the starting PANI nanotubes by EPR spectroscopy.

  9. FLUIDIZATION OF CARBON NANOTUBES

    Institute of Scientific and Technical Information of China (English)

    Fei Wei; Cang Huang; Yao Wang

    2005-01-01

    Carbon nanotubes (CNTs) can be fluidized in the form of fluidlike agglomerates made of many three-dimensional sub-agglomerates, having a multi-stage agglomerate (MSA) structure and containing large amounts of twisting CNTs of micrometer magnitude.

  10. Carbon nanotubes: Fibrillar pharmacology

    Science.gov (United States)

    Kostarelos, Kostas

    2010-10-01

    The mechanisms by which chemically functionalized carbon nanotubes flow in blood and are excreted through the kidneys illustrate the unconventional behaviour of these fibrillar nanostructures, and the opportunities they offer as components for the design of advanced delivery vehicles.

  11. Electrocatalytic determination of dopamine in the presence of uric acid using an indenedione derivative and multiwall carbon nanotubes spiked in carbon paste electrode

    Energy Technology Data Exchange (ETDEWEB)

    Nasirizadeh, Navid, E-mail: nasirizadeh@yahoo.com [Scientific Society of Nanotechnology, Yazd Branch, Islamic Azad University, Yazd (Iran, Islamic Republic of); Department of Textile Engineering, Yazd Branch, Islamic Azad University, Yazd (Iran, Islamic Republic of); Shekari, Zahra [Scientific Society of Nanotechnology, Yazd Branch, Islamic Azad University, Yazd (Iran, Islamic Republic of); Zare, Hamid R. [Department of Chemistry, Yazd University, P.O. Box 89195-741, Yazd (Iran, Islamic Republic of); Makarem, Somayeh [Department of Chemistry, Faculty of Sciences, ShahidBeheshti University, G. C., P. O. Box 19839-4716, Tehran (Iran, Islamic Republic of)

    2013-04-01

    In the present study, a modified carbon paste electrode (CPE) containing multi-wall carbon nanotubes and an indenedione derivative(IMWCNT−CPE) was constructed and was successfully used for dopamine(DA) electrocatalytic oxidation and simultaneous determination of DA and uric acid (UA). Cyclic voltammograms of the IMWCNT−CPE show a pair of well-defined and reversible redox. The obtained results indicate that the peak potential of DA oxidation at IMWCNT−CPE shifted by about 65 and 185 mV toward the negative values compared with that at a MWCNT and indenedione modified CPE, respectively. The electron transfer coefficient, α, and the heterogeneous electron transfer rate constant, k′, for the oxidation of DA at IMWCNT−CPE were calculated 0.4 ± 0.01 and (1.13 ± 0.03) × 10{sup −3} cm s{sup −1}, respectively. Furthermore, differential pulse voltammetry (DPV) exhibits two linear dynamic ranges of 1.9–79.4 μM, and 79.4–714.3 μM and a detection limit of 0.52 μM for DA determination. Then IMWCNT−CPE was applied to the simultaneous determination of DA and UA with DPV. Finally, the activity of the modified electrode was also investigated for determination of DA and UA in real samples, such as injection solution of DA and urine, with satisfactory results. - Highlights: ► According to referee's comment we have omitted references 33–35. ► Fig. 1 of the revised manuscript was improved based on referee comment. ► We have calculated the effective areas of MWCNT−CPE and unmodified CPE. ► Differential pulse voltammetry was used to estimate the quantitative parameters. ► Based on referee comment, the necessary corrections at the references list were mad.

  12. Composite carbon foam electrode

    Science.gov (United States)

    Mayer, S.T.; Pekala, R.W.; Kaschmitter, J.L.

    1997-05-06

    Carbon aerogels used as a binder for granulated materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivity and power to system energy. 1 fig.

  13. Nanotube composite carbon fibers

    Science.gov (United States)

    Andrews, R.; Jacques, D.; Rao, A. M.; Rantell, T.; Derbyshire, F.; Chen, Y.; Chen, J.; Haddon, R. C.

    1999-08-01

    Single walled carbon nanotubes (SWNTs) were dispersed in isotropic petroleum pitch matrices to form nanotube composite carbon fibers with enhanced mechanical and electrical properties. We find that the tensile strength, modulus, and electrical conductivity of a pitch composite fiber with 5 wt % loading of purified SWNTs are enhanced by ˜90%, ˜150%, and 340% respectively, as compared to the corresponding values in unmodified isotropic pitch fibers. These results serve to highlight the potential that exits for developing a spectrum of material properties through the selection of the matrix, nanotube dispersion, alignment, and interfacial bonding.

  14. Synthesis and characterization of novel dopamine-derivative:Application of modified multi-wall carbon nanotubes paste electrode for electrochemical investigation

    Institute of Scientific and Technical Information of China (English)

    Shadpour Mallakpour; Mehdi Hatami; Ali A. Ensafi; Hassan Karimi-Maleh

    2011-01-01

    Novel dopamine-derivative compound, 3,5-diamino-N-(3,4-dihydroxyphenethyl)benzamide (3,5-DAB) was prepared in two steps. In the first step dopamine hydrochloride was reacted with 3,5-dinitrobenzoyl chloride in the presence of propylene oxide. In the second step reduction of nitro groups resulted in preparation of 3,5-DAB in quantitative yield. This material was characterized using conventional spectroscopic methods such as FT-IR and 1H NMR. In addition, the redox response of a modified carbon nanotubes paste electrode of 3,5-DAB was investigated in aqueous solution at a neutral pH. The result showed that the electrode process has a guasi-reversible response, with △Ep, greater than the (59/n) mV expected for a reversible system. Finally, the diffusion coefficient for redox process in paraffin oil matrix obtained using chronoamperometry methods.

  15. Studies on the heterogeneous electron transport and oxygen reduction reaction at metal (Co, Fe) octabutylsulphonylphthalocyanines supported on multi-walled carbon nanotube modified graphite electrode

    International Nuclear Information System (INIS)

    Heterogeneous electron transfer dynamics and oxygen reduction reaction (ORR) activities using octabutylsulphonylphthalocyanine complexes of iron (FeOBSPc) and cobalt (CoOBSPc) supported on multi-walled carbon nanotube (MWCNT) platforms have been described. The MWCNT-based electrodes (MWCNT-CoOBSPc and MWCNT-FeOBSPc) showed larger Faradaic current responses than the electrodes without the MWCNTs, interpreted as a consequence of the trapped electrolyte species within the porous layers of MWCNTs undergoing a redox process. The EPPGE-MWCNT-FeOBSPc showed onset potential (-0.01 V vs Ag|AgCl) which is comparable and even much lower than recent reports. The MWCNT-FeOBSPc showed the best ORR activity involving a direct 4-electron mechanism, with a Tafel slope of about 124 mV, indicating a 1-electron process in the rate-determining step.

  16. Facile stripping voltammetric determination of haloperidol using a high performance magnetite/carbon nanotube paste electrode in pharmaceutical and biological samples

    International Nuclear Information System (INIS)

    Multi-walled carbon nanotubes decorated with Fe3O4 nanoparticles were prepared to construct a novel sensor for the determination of haloperidol (Hp) by voltammetric methods. The morphology and properties of electrode surface were characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy. This modified sensor was used as a selective electrochemical sensor for the determination of trace amounts of Hp. The peak currents of differential pulse and square wave voltammograms of Hp increased linearly with its concentration in the ranges of 1.2 × 10−3–0.52 and 6.5 × 10−4–0.52 μmol L−1, respectively. The detection limits for Hp were 7.02 × 10−4 and 1.33 × 10−4 μmol L−1 for differential pulse and square wave voltammetric methods, respectively. The results show that the combination of multi-walled carbon nanotubes and Fe3O4 nanoparticles causes a dramatic enhancement in the sensitivity of Hp quantification. This sensor was successfully applied to determine Hp in pharmaceutical samples and biological fluids. The fabricated electrode showed excellent reproducibility, repeatability and stability. - Highlights: • A sensitive paste using Fe3O4/multi-walled carbon nanotubes was fabricated. • Haloperidol determination is based on its adsorption on the surface of Fe3O4/MWCNTs. • Different electrochemical methods and impedance spectroscopy were used for this study. • Haloperidol was determined in pharmaceutical and biological samples. • In comparison to other conventional methods, this method is simple, rapid, selective and cost-effective

  17. Facile stripping voltammetric determination of haloperidol using a high performance magnetite/carbon nanotube paste electrode in pharmaceutical and biological samples

    Energy Technology Data Exchange (ETDEWEB)

    Bagheri, Hasan, E-mail: h.bagheri@srbiau.ac.ir [Chemical Injuries Research Center, Baqiyatallah University of Medical Sciences, Tehran (Iran, Islamic Republic of); Afkhami, Abbas [Faculty of Chemistry, Bu-Ali Sina University, Hamedan (Iran, Islamic Republic of); Panahi, Yunes [Chemical Injuries Research Center, Baqiyatallah University of Medical Sciences, Tehran (Iran, Islamic Republic of); Khoshsafar, Hosein; Shirzadmehr, Ali [Faculty of Chemistry, Bu-Ali Sina University, Hamedan (Iran, Islamic Republic of)

    2014-04-01

    Multi-walled carbon nanotubes decorated with Fe{sub 3}O{sub 4} nanoparticles were prepared to construct a novel sensor for the determination of haloperidol (Hp) by voltammetric methods. The morphology and properties of electrode surface were characterized by scanning electron microscopy (SEM) and electrochemical impedance spectroscopy. This modified sensor was used as a selective electrochemical sensor for the determination of trace amounts of Hp. The peak currents of differential pulse and square wave voltammograms of Hp increased linearly with its concentration in the ranges of 1.2 × 10{sup −3}–0.52 and 6.5 × 10{sup −4}–0.52 μmol L{sup −1}, respectively. The detection limits for Hp were 7.02 × 10{sup −4} and 1.33 × 10{sup −4} μmol L{sup −1} for differential pulse and square wave voltammetric methods, respectively. The results show that the combination of multi-walled carbon nanotubes and Fe{sub 3}O{sub 4} nanoparticles causes a dramatic enhancement in the sensitivity of Hp quantification. This sensor was successfully applied to determine Hp in pharmaceutical samples and biological fluids. The fabricated electrode showed excellent reproducibility, repeatability and stability. - Highlights: • A sensitive paste using Fe{sub 3}O{sub 4}/multi-walled carbon nanotubes was fabricated. • Haloperidol determination is based on its adsorption on the surface of Fe{sub 3}O{sub 4}/MWCNTs. • Different electrochemical methods and impedance spectroscopy were used for this study. • Haloperidol was determined in pharmaceutical and biological samples. • In comparison to other conventional methods, this method is simple, rapid, selective and cost-effective.

  18. Multi-layer electrode with nano-Li4Ti5O12 aggregates sandwiched between carbon nanotube and graphene networks for high power Li-ion batteries

    Science.gov (United States)

    Choi, Jin-Hoon; Ryu, Won-Hee; Park, Kyusung; Jo, Jeong-Dai; Jo, Sung-Moo; Lim, Dae-Soon; Kim, Il-Doo

    2014-12-01

    Self-aggregated Li4Ti5O12 particles sandwiched between graphene nanosheets (GNSs) and single-walled carbon nanotubes (SWCNTs) network are reported as new hybrid electrodes for high power Li-ion batteries. The multi-layer electrodes are fabricated by sequential process comprising air-spray coating of GNSs layer and the following electrostatic spray (E-spray) coating of well-dispersed colloidal Li4Ti5O12 nanoparticles, and subsequent air-spray coating of SWCNTs layer once again. In multi-stacked electrodes of GNSs/nanoporous Li4Ti5O12 aggregates/SWCNTs networks, GNSs and SWCNTs serve as conducting bridges, effectively interweaving the nanoporous Li4Ti5O12 aggregates, and help achieve superior rate capability as well as improved mechanical stability of the composite electrode by holding Li4Ti5O12 tightly without a binder. The multi-stacked electrodes deliver a specific capacity that maintains an impressively high capacity of 100 mA h g-1 at a high rate of 100C even after 1000 cycles.

  19. In Situ-Grown ZnCo2O4 on Single-Walled Carbon Nanotubes as Air Electrode Materials for Rechargeable Lithium–Oxygen Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Bin; Xu, Wu; Yan, Pengfei; Bhattacharya, Priyanka; Cao, Ruiguo; Bowden, Mark E.; Engelhard, Mark H.; Wang, Chong M.; Zhang, Jiguang

    2015-10-12

    Although lithium-oxygen (Li-O2) batteries have great potential to be used as one of the next generation energy storage systems due to their ultrahigh theoretical specific energy, there are still many significant barriers before their practical applications. These barriers include electrolyte and electrode instability, poor ORR/OER efficiency and cycling capability, etc. Development of a highly efficient catalyst will not only enhance ORR/OER efficiency, it may also improve the stability of electrolyte because the reduced charge voltage. Here we report the synthesis of nano-sheet-assembled ZnCo2O4 spheres/single walled carbon nanotubes (ZCO/SWCNTs) composites as high performance air electrode materials for Li-O2 batteries. The ZCO catalyzed SWCNTs electrodes delivered high discharge capacities, decreased the onset of oxygen evolution reaction by 0.9 V during charge processes, and led to more stable cycling stability. These results indicate that ZCO/SWCNTs composite can be used as highly efficient air electrode for oxygen reduction and evolution reactions. The highly enhanced catalytic activity by uniformly dispersed ZnCo2O4 catalyst on nanostructured electrodes is expected to inspire

  20. Simultaneous detection of ascorbic acid, dopamine, uric acid and tryptophan with Azure A-interlinked multi-walled carbon nanotube/gold nanoparticles composite modified electrode

    Directory of Open Access Journals (Sweden)

    Hayati Filik

    2016-05-01

    Full Text Available In this paper, multi-walled carbon nanotube/Azure A/gold nanoparticle composites (Nafion/AuNPs/AzA/MWCNTs were prepared by binding gold nanoparticles to the surfaces of Azure A-coated carbon nanotubes. Nafion/AuNPs/AzA/MWCNTs based electrochemical sensor was fabricated for the simultaneous determination of ascorbic acid, dopamine, uric acid, and tryptophan. Cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the electrochemical properties of the modified electrodes. The modified electrode showed excellent electrocatalytic activity toward ascorbic acid, dopamine, uric acid, and tryptophan (pH 7.0. The experiment results showed that the linear response range for simultaneous detection of AA, DA, UA and Trp were 300–10,000 μM, 0.5–50 μM, 0.5–50 μM and 1.0–100 μM, respectively, and the detection limits were 16 μM, 0.014 μM, 0.028 μM and 0.56 μM (S/N = 3. The proposed method offers promise for simple, rapid, selective and cost-effective analysis of small biomolecules. The procedure was also applied to the determination of tryptophan in spiked milk samples.

  1. Suppression of single-molecule conductance fluctuations using extended anchor groups on graphene and carbon-nanotube electrodes

    Science.gov (United States)

    Péterfalvi, Csaba G.; Lambert, Colin J.

    2012-08-01

    Devices formed from single molecules attached to noble-metal electrodes exhibit large conductance fluctuations, which inhibit their development as reproducible functional units. We demonstrate that single molecules with planar anchor groups attached to carbon-based electrodes are more resilient to atomic-scale variation in the contacts and exhibit significantly lower conductance fluctuations. We examine the conductance of a 2,6-dibenzylamino core-substituted naphthalenediimide chromophore attached to carbon electrodes by either phenanthrene anchors or more extended anchor groups, which include oligophenylene ethynylene spacers. We demonstrate that for the more spatially extended anchor groups conductance fluctuations are significantly reduced. The current-voltage characteristic arising from long-range tunneling is found to be strongly nonlinear with pronounced conductance suppression below a threshold voltage of approximately 2.5 V.

  2. Effect of solution conductivity and electrode shape on the deposition of carbon nanotubes from solution using dielectrophoresis

    International Nuclear Information System (INIS)

    Dielectrophoresis (DEP) is a popular technique for fabricating carbon nanotube (CNT) devices. The electric current passing through the solution during DEP creates a temperature gradient, which results in electrothermal fluid flow because of the presence of the electric field. CNT solutions prepared with various methods can have different conductivities and the motion of the solution because of the electrothermal phenomenon can affect the DEP deposition differently in each case. We investigated the effect of this movement in solutions with various levels of conductivity through experiments as well as numerical modeling. Our results show that electrothermal motion in the solution can alter the deposition pattern of the nanotubes drastically for high conductivity solutions, while DEP remains the dominant force when a low conductivity (surfactant-free) solution is used. The extent of effectiveness of each force is discussed in the various cases and the fluid movement model is investigated using two- and three-dimensional finite element simulations. (paper)

  3. A Novel Activated-Charcoal-Doped Multiwalled Carbon Nanotube Hybrid for Quasi-Solid-State Dye-Sensitized Solar Cell Outperforming Pt Electrode.

    Science.gov (United States)

    Arbab, Alvira Ayoub; Sun, Kyung Chul; Sahito, Iftikhar Ali; Qadir, Muhammad Bilal; Choi, Yun Seon; Jeong, Sung Hoon

    2016-03-23

    Highly conductive mesoporous carbon structures based on multiwalled carbon nanotubes (MWCNTs) and activated charcoal (AC) were synthesized by an enzymatic dispersion method. The synthesized carbon configuration consists of synchronized structures of highly conductive MWCNT and porous activated charcoal morphology. The proposed carbon structure was used as counter electrode (CE) for quasi-solid-state dye-sensitized solar cells (DSSCs). The AC-doped MWCNT hybrid showed much enhanced electrocatalytic activity (ECA) toward polymer gel electrolyte and revealed a charge transfer resistance (RCT) of 0.60 Ω, demonstrating a fast electron transport mechanism. The exceptional electrocatalytic activity and high conductivity of the AC-doped MWCNT hybrid CE are associated with its synchronized features of high surface area and electronic conductivity, which produces higher interfacial reaction with the quasi-solid electrolyte. Morphological studies confirm the forms of amorphous and conductive 3D carbon structure with high density of CNT colloid. The excessive oxygen surface groups and defect-rich structure can entrap an excessive volume of quasi-solid electrolyte and locate multiple sites for iodide/triiodide catalytic reaction. The resultant D719 DSSC composed of this novel hybrid CE fabricated with polymer gel electrolyte demonstrated an efficiency of 10.05% with a high fill factor (83%), outperforming the Pt electrode. Such facile synthesis of CE together with low cost and sustainability supports the proposed DSSCs' structure to stand out as an efficient next-generation photovoltaic device. PMID:26911208

  4. Carbon nanotubes decorating methods

    Directory of Open Access Journals (Sweden)

    A.D. Dobrzańska-Danikiewicz

    2013-06-01

    Full Text Available Purpose: The work is to present and characterise various methods of depositing carbon nanotubes with nanoparticles of precious metals, and also to present the results of own works concerning carbon nanotubes coated with platinum nanoparticles.Design/methodology/approach: Electron transmission and scanning microscopy has been used for imaging the structure and morphology of the nanocomposites obtained and the distribution of nanoparticles on the surface of carbon nanotubes.Findings: The studies carried out with the HRTEM and SEM techniques have confirmed differences in morphology, homogeneity and density of depositing platinum nanoparticles on the surface of carbon nanotubes and its structure.Research limitations/implications: The studies conducted pertained to the process of decorating carbon nanotubes with platinum nanoparticles. Further works are planned aimed at extending the application scope of the newly developed methodology to include the methods of nanotubes decorating with the nanoparticles of other precious metals (mainly palladium and rhodium.Practical implications: CNTs-NPs (Carbon NanoTube-NanoParticles composites can be used as the active elements of sensors featuring high sensitivity, fast action, high selectivity and accuracy, in particular in medicine as cholesterol and glucoses sensors; in the automotive industry for the precision monitoring of working parameters in individual engine components; in environmental conservation to examine CO2, NOx, and CH4 concentrations and for checking leak-tightness and detecting hazardous substances in household and industrial gas installations.Originality/value: The comprehensive characterisation of the methods employed for fabricating nanocomposites consisting of carbon nanotubes deposited with Pt, Pd, Rh, Au, Ag nanoparticles with special consideration to the colloidal process.

  5. Electroanalysis with carbon paste electrodes

    CERN Document Server

    Svancara, Ivan; Walcarius, Alain; Vytras, Karel

    2011-01-01

    Introduction to Electrochemistry and Electroanalysis with Carbon Paste-Based ElectrodesHistorical Survey and GlossaryField in Publication Activities and LiteratureCarbon Pastes and Carbon Paste ElectrodesCarbon Paste as the Binary MixtureClassification of Carbon Pastes and Carbon Paste ElectrodesConstruction of Carbon Paste HoldersCarbon Paste as the Electrode MaterialPhysicochemical Properties of Carbon PastesElectrochemical Characteristics of Carbon PastesTesting of Unmodified CPEsIntera

  6. A carbon nanotube-based sensing element

    Institute of Scientific and Technical Information of China (English)

    YANG Xing; ZHOU Zhao-ying; WU Ying; ZHANG Jin; ZHANG Ying-ying

    2007-01-01

    A carbon nanotube-based(CNT) sensing element is presented, which consists of substrate, insulating layer, electrodes,carbon nanotube and measuring circuit. The sensing components are a single or array of CNTs, which are located on the two electrodes. The CNT-based sensing element is fabricated by CVD (chemical vapor deposition)-direct-growth on microelectrodes. The sensing model and measurement method of electromechanical property are also presented. Finally, the voltage-current characteristics are measured, which show that the CNT-based sensing element has good electrical properties.

  7. Carbon Nanotube Tower-Based Supercapacitor

    Science.gov (United States)

    Meyyappan, Meyya (Inventor)

    2012-01-01

    A supercapacitor system, including (i) first and second, spaced apart planar collectors, (ii) first and second arrays of multi-wall carbon nanotube (MWCNT) towers or single wall carbon nanotube (SWCNT) towers, serving as electrodes, that extend between the first and second collectors where the nanotube towers are grown directly on the collector surfaces without deposition of a catalyst and without deposition of a binder material on the collector surfaces, and (iii) a porous separator module having a transverse area that is substantially the same as the transverse area of at least one electrode, where (iv) at least one nanotube tower is functionalized to permit or encourage the tower to behave as a hydrophilic structure, with increased surface wettability.

  8. Templated Growth of Carbon Nanotubes

    Science.gov (United States)

    Siochik Emilie J. (Inventor)

    2007-01-01

    A method of growing carbon nanotubes uses a synthesized mesoporous si lica template with approximately cylindrical pores being formed there in. The surfaces of the pores are coated with a carbon nanotube precu rsor, and the template with the surfaces of the pores so-coated is th en heated until the carbon nanotube precursor in each pore is convert ed to a carbon nanotube.

  9. Hydrogen peroxide biosensor based on gold nanoparticles/thionine/gold nanoparticles/multi-walled carbon nanotubes-chitosans composite film-modified electrode

    Energy Technology Data Exchange (ETDEWEB)

    Li Shenfeng; Zhu Xiaoying; Zhang Wei; Xie Guoming [Key Laboratory of Laboratory Medical Diagnostics, Ministry of Education, Department of Laboratory Medicine, Chongqing Medical University, Chongqing 400016 (China); Feng Wenli, E-mail: fengwlcqmu@sina.com [Key Laboratory of Laboratory Medical Diagnostics, Ministry of Education, Department of Laboratory Medicine, Chongqing Medical University, Chongqing 400016 (China)

    2012-01-15

    In this paper, an amperometric electrochemical biosensor for the detection of hydrogen peroxide (H{sub 2}O{sub 2}), based on gold nanoparticles (GNPs)/thionine (Thi)/GNPs/multi-walled carbon nanotubes (MWCNTs)-chitosans (Chits) composite film was developed. MWCNTs-Chits homogeneous composite was first dispersed in acetic acid solution and then the GNPs were in situ synthesized at the composite. The mixture was dripped on the glassy carbon electrode (GCE) and then the Thi was deposited by electropolymerization by Au-S or Au-N covalent bond effect and electrostatic adsorption effect as an electron transfer mediator. Finally, the mixture of GNPs and horseradish peroxidase (HRP) was assembled onto the modified electrode by covalent bond. The electrochemical behavior of the modified electrode was investigated by scanning electron microscope, cyclic voltammetry and chronoamperometry. This study introduces the in situ-synthesized GNPs on the other surface of the modified materials in H{sub 2}O{sub 2} detection. The linear response range of the biosensor to H{sub 2}O{sub 2} concentration was from 5 Multiplication-Sign 10{sup -7} mol L{sup -1} to 1.5 Multiplication-Sign 10{sup -3} mol L{sup -1} with a detection limit of 3.75 Multiplication-Sign 10{sup -8} mol L{sup -1} (based on S/N = 3).

  10. A high-performance glucose biosensor using covalently immobilised glucose oxidase on a poly(2,6-diaminopyridine)/carbon nanotube electrode.

    Science.gov (United States)

    Ali Kamyabi, Mohammad; Hajari, Nasim; Turner, Anthony P F; Tiwari, Ashutosh

    2013-11-15

    A highly-sensitive glucose biosensor amenable to ultra-miniaturisation was fabricated by immobilisation of glucose oxidase (GOx), onto a poly(2,6-diaminopyridine)/multi-walled carbon nanotube/glassy carbon electrode (poly(2,6-DP)/MWNT/GCE). Cyclic voltammetry was used for both the electrochemical synthesis of poly-(2,6-DP) on the surface of a MWNT-modified GC electrode, and characterisation of the polymers deposited on the GC electrode. The synergistic effect of the high active surface area of both the conducting polymer, i.e., poly-(2,6-DP) and MWNT gave rise to a remarkable improvement in the electrocatalytic properties of the biosensor. The transfer coefficient (α), heterogeneous electron transfer rate constant and Michaelis-Menten constant were calculated to be 0.6, 4 s(-1) and 0.20 mM at pH 7.4, respectively. The GOx/poly(2,6-DP)/MWNT/GC bioelectrode exhibited two linear responses to glucose in the concentration ranging from 0.42 μM to 8.0 mM with a correlation coefficient of 0.95, sensitivity of 52.0 μA mM(-1) cm(-2), repeatability of 1.6% and long-term stability, which could make it a promising bioelectrode for precise detection of glucose in the biological samples. PMID:24148477

  11. Lithium storage properties of multiwall carbon nanotubes prepared by CVD

    International Nuclear Information System (INIS)

    Full text: Multiwall carbon nanotubes (MWCNTs) were synthesised by chemical vapour deposition (CVD) method using acetylene gas. The XRD pattern of as prepared carbon nanotubes showed that the d002 value is 3.44 Angstroms. The morphology and microstructure of carbon nanotubes were characterized by HRTEM. Most of carbon nanotubes are entangled together to form bundles or ropes. The diameter of the carbon nanotubes is in the range of 10 ∼ 20 nm. There is a small amount of amorphous carbon particles presented in the sample. However, the yield of carbon nanotubes is more than 95%. Electrochemical properties of carbon nanotubes were characterised via a variety of electrochemical testing techniques. The result of CV test showed that the Li insertion potential is quite low, which is very close to O V versus Li+/Li reference electrode, whereas the potential for Li de-intercalation is in the range of 0.2-0.4 V. There exists a slight voltage hysteresis between Li intercalation and Li de-intercalation, which is similar to the other carbonaceous materials. The intensity of redox peaks of carbon nanotubes decrease with scanning cycle, indicating that the reversible Li insertion capacity gradually decreases. The carbon nanotubes electrode demonstrated a reversible lithium storage capacity of 340 mAh/g with good cyclability at moderate current density. Further improvement of Li storage capacity is possible by opening the end of carbon nanotubes to allow lithium insertion into inner graphene sheet of carbon nanotubes. The kinetic properties of lithium insertion in carbon nanotube electrodes were characterised by a.c. impedance measurements. It was found that the lithium diffusion coefficient dLi decreases with an increase of Li ion concentration in carbon nanotube host

  12. Carbon Nanotubes for Supercapacitor

    Directory of Open Access Journals (Sweden)

    Li Jianyi

    2010-01-01

    Full Text Available Abstract As an electrical energy storage device, supercapacitor finds attractive applications in consumer electronic products and alternative power source due to its higher energy density, fast discharge/charge time, low level of heating, safety, long-term operation stability, and no disposable parts. This work reviews the recent development of supercapacitor based on carbon nanotubes (CNTs and their composites. The purpose is to give a comprehensive understanding of the advantages and disadvantages of carbon nanotubes-related supercapacitor materials and to find ways for the improvement in the performance of supercapacitor. We first discussed the effects of physical and chemical properties of pure carbon nanotubes, including size, purity, defect, shape, functionalization, and annealing, on the supercapacitance. The composites, including CNTs/oxide and CNTs/polymer, were further discussed to enhance the supercapacitance and keep the stability of the supercapacitor by optimally engineering the composition, particle size, and coverage.

  13. Horizontal carbon nanotube alignment.

    Science.gov (United States)

    Cole, Matthew T; Cientanni, Vito; Milne, William I

    2016-09-21

    The production of horizontally aligned carbon nanotubes offers a rapid means of realizing a myriad of self-assembled near-atom-scale technologies - from novel photonic crystals to nanoscale transistors. The ability to reproducibly align anisotropic nanostructures has huge technological value. Here we review the present state-of-the-art in horizontal carbon nanotube alignment. For both in and ex situ approaches, we quantitatively assess the reported linear packing densities alongside the degree of alignment possible for each of these core methodologies. PMID:27546174

  14. Nanocomposite electrodes based on pre-synthesized organically capped platinum nanoparticles and carbon nanotubes. Part I: Tuneable low platinum loadings, specific H upd feature and evidence for oxygen reduction

    International Nuclear Information System (INIS)

    A bottom-up approach is used here to combine carbon nanotubes synthesized by CVD and organically capped platinum nanoparticles electrocatalyst exhibiting a direct electrochemical activity towards oxygen reduction. Both nano-objects are handled in liquid suspension and are associated together in a controlled way. The nanocomposite liquid dispersions can be precisely controlled in terms of platinum nanoparticles to carbon nanotubes weight ratios (NP/NT) which correspond to different coverages of nanotubes by nanoparticles. Electrodes with low to ultra-low platinum loadings can then be prepared on porous fuel cell carbon supports by filtration. The direct electrochemical activity towards aqueous oxygen reduction reaction (ORR) of electrodes with platinum loadings ranging from about 1 to 60 μg/cm2 is reported without any activation step in order to keep the features of the nanoparticles intact. Before that, we studied the responses obtained when impregnating our hydrophobic electrodes by a voltamperometric gas consumption procedure. These responses are also dependent of the composition of our electrodes. Whereas our results are of particular interest with respect to the optimization of platinum loading in fuel cell electrodes, the specific behaviour of these capped platinum nanoparticles towards proton adsorption-desorption reveals the difficulty to determine reliable active surface area with related regard to the platinum loading and point to the necessity to determine other characteristic parameters for the electrodes.

  15. Deposition of new thia-containing Schiff-base iron (III) complexes onto carbon nanotube-modified glassy carbon electrodes as a biosensor for electrooxidation and determination of amino acids

    Energy Technology Data Exchange (ETDEWEB)

    Saghatforoush, Lotfali [Department of Chemistry, Faculty of Science, Payame Noor University (PNU), P.O. Box 58168-45164, Khoy (Iran, Islamic Republic of); Hasanzadeh, Mohammad, E-mail: mhmmd_hasanzadeh@yahoo.co [Department of Chemistry, Faculty of Science, Payame Noor University (PNU), P.O. Box 58168-45164, Khoy (Iran, Islamic Republic of); Department of Chemistry, Faculty of Science, K.N. Toosi University of Technology (KNTU), Tehran (Iran, Islamic Republic of); Shadjou, Nasrin [Department of Chemistry, Faculty of Science, Payame Noor University (PNU), P.O. Box 58168-45164, Khoy (Iran, Islamic Republic of); Department of Chemistry, Faculty of Science, K.N. Toosi University of Technology (KNTU), Tehran (Iran, Islamic Republic of); Khalilzadeh, Balal [Department of Analytical Chemistry, Faculty of Science, Arak University, Arak (Iran, Islamic Republic of)

    2011-01-01

    Multiwall carbon nanotubes (MWCNTs) were used as an immobilization matrix to incorporate an Fe (III)-Schiff base complex as an electron-transfer mediator onto a glassy carbon electrode surface. First, the preheated glassy carbon was subjected to abrasive immobilization of MWCNTs by gently rubbing the electrode surface on filter paper supporting the carbon nanotubes. Second, the electrode surface was modified by casting 100 {mu}L of an Fe (III)-complex solution (0.01 M in ACN). The cyclic voltammograms of the modified electrode in an aqueous solution displayed a pair of well-defined, stable and nearly reversible reductive oxidation redox systems with surface confined characteristics. Combinations of unique electronic and electrocatalytic properties of MWCNTs and Fe (III)-Schiff base complexes resulted in a remarkable synergistic augmentation of the response. The electrochemical behavior and stability of the modified electrode in aqueous solutions at pH 1-9 were characterized by cyclic voltammetry. The apparent electron transfer rate constant (K{sub s}) and transfer coefficient (a) were determined by cyclic voltammetry and were approximately 7 s{sup -1} and 0.55, respectively. The modified electrodes showed excellent catalytic activity towards the oxidation of amino acids at an unusually positive potential in acidic solution. They also displayed inherent stability at a wide pH range, fast response time, high sensitivity, low detection limit and had a remarkably positive potential oxidation of amino acids that decreased the effect of interferences in analysis. The linear concentration range, limits of detection (LOD), limits of quantization (LOQ) and relative standard deviation of the proposed sensor for the amino acid detection were 1-55,000, 1.10-13.70, 2.79-27.14 and 1.30-5.11, respectively.

  16. Carbon nanotube junctions and devices

    OpenAIRE

    Postma, H. W. Ch.

    2001-01-01

    In this thesis Postma presents transport experiments performed on individual single-wall carbon nanotubes. Carbon nanotubes are molecules entirely made of carbon atoms. The electronic properties are determined by the exact symmetry of the nanotube lattice, resulting in either metallic or semiconducting behaviour. Due to their small diameter, electronic motion is directed in the length direction of the nanotube, making them ideal systems to study e.g. one-dimensional transport phenomena. First...

  17. Two-ply yarn supercapacitor based on carbon nanotube/stainless steel core-sheath yarn electrodes and ionic liquid electrolyte

    Science.gov (United States)

    Lyu, Xiaoming; Su, Fenghua; Miao, Menghe

    2016-03-01

    Linear supercapacitors have great potential as power source in electronic textiles. However, the energy density of most yarn supercapacitors reported so far is still quite low and decreases significantly as the supercapacitor length increases. Here, we report a two-ply yarn supercapacitor based on carbon nanotube/stainless steel core-sheath yarn electrode and ionic liquid electrolyte. The use of IL gel electrolyte widens the potential window of supercapacitor from 1.0 V to 2.7 V. The carbon nanotube/stainless steel core-sheath yarn structure greatly improves the charge transport efficiency and allows the length of the linear supercapacitor to be significantly scaled up. The resulting supercapacitor has shown outstanding electrochemical performances with a high volumetric capacitance of 263.31 F cm-3 and energy density of 6.67×10-2 Wh cm-3. The two-ply yarn supercapacitors are also very flexible and strong for use as sewing thread and for making knots without significant loss of their energy storage capacity.

  18. Carbon nanotube cathode with capping carbon nanosheet

    Science.gov (United States)

    Li, Xin; Zhao, Dengchao; Pang, Kaige; Pang, Junchao; Liu, Weihua; Liu, Hongzhong; Wang, Xiaoli

    2013-10-01

    Here, we report a vertically aligned carbon nanotube (VACNT) film capped with a few layer of carbon nanosheet (FLCN) synthesized by chemical vapor deposition using a carbon source from iron phthalocyanine pyrolysis. The square resistance of the VACNT film is significantly reduced from 1500 Ω/□ to 300 Ω/□ when it is capped with carbon nanosheet. The VACNT capped with carbon nanosheet was transferred to an ITO glass substrate in an inverted configuration so that the carbon nanosheet served as a flexible transparent electrode at the bottom and the VACNT roots served as emission tips. Because all of the VACNTs start growing from a flat silicon substrate, the VACNT roots are very neat and uniform in height. A field emission test of the carbon nanosheet-capped VACNT film proved that the CNT roots show better uniformity in field emission and the carbon nanosheet cap could also potentially serve as a flexible transparent electrode, which is highly desired in photo-assisted field emission.

  19. Electrochemical performance of polyaniline nanofibres and polyaniline/multi-walled carbon nanotube composite as an electrode material for aqueous redox supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Sivakkumar, S.R.; Kim, Wan Ju; Choi, Ji-Ae; Kim, Dong-Won [Department of Applied Chemistry, Hanbat National University, Yusung-Gu, Daejeon 305-719 (Korea); MacFarlane, Douglas R. [School of Chemistry, Monash University, Wellington Road, Clayton, Vic. 3800 (Australia); Forsyth, Maria [Department of Materials Engineering, Monash University, Wellington Road, Clayton, Vic. 3800 (Australia)

    2007-09-27

    Polyaniline (PANI) nanofibres are synthesized by interfacial polymerization and their electrochemical performance is evaluated in an aqueous redox supercapacitor constituted as a two-electrode cell. The initial specific capacitance of the cell is 554 F g{sup -1} at a constant current of 1.0 A g{sup -1}, but this value rapidly decreases on continuous cycling. In order to improve the cycleability of the supercapacitor, a composite of polyaniline with multi-walled carbon nanotubes (CNTs) is synthesized by in situ chemical polymerization. Its capacitive behaviour is evaluated in a similar cell configuration. A high initial specific capacitance of 606 F g{sup -1} is obtained with good retention on cycling. In both supercapacitors, the effect of charging potential on cycling performances is investigated. (author)

  20. Transport Through Carbon Nanotube Wires

    Science.gov (United States)

    Anantram, M. P.; Kwak, Dochan (Technical Monitor)

    2001-01-01

    This viewgraph presentation deals with the use of carbon nanotubes as a transport system. Contact, defects, tubular bend, phonons, and mechanical deformations all contribute to reflection within the nanotube wire. Bragg reflection, however, is native to an ideal energy transport system. Transmission resistance depends primarily on the level of energy present. Finally, the details regarding coupling between carbon nanotubes and simple metals are presented.

  1. Highly sensitive and simultaneous electrochemical determination of 2-aminophenol and 4-aminophenol based on poly(l-arginine)-β-cyclodextrin/carbon nanotubes@graphene nanoribbons modified electrode.

    Science.gov (United States)

    Yi, Yinhui; Zhu, Gangbing; Wu, Xiangyang; Wang, Kun

    2016-03-15

    Owing to the similar characteristics and physiochemical property of 2-aminophenol (2-AP) and 4-aminophenol (4-AP), the highly sensitive simultaneous electrochemical determination of 2- and 4-AP is a great challenge. In this paper, by electropolymerizing β-cyclodextrin (β-CD) and l-arginine (l-Arg) on the surface of carbon nanotubes@graphene nanoribbons (CNTs@GNRs) core-shell heterostructure, a P-β-CD-l-Arg/CNTs@GNRs nanohybrid modified electrode was prepared successfully, and it could exhibit the synergetic effects of β-CD (high host-guest recognition and enrichment ability), l-Arg (excellent electrocatalytic activity) and CNTs@GNRs (prominent electrochemical properties and large surface area), the P-β-CD-l-Arg/CNTs@GNRs modified electrode was used in the electrochemical determination of 2- and 4-AP, the results demonstrated that the highly sensitive and simultaneous determination of 2- and 4-AP is successfully achieved and the modified electrode has a linear response range of 25.0-1300.0 nM for both 2- and 4-AP, and the detection limits of 2- and 4-AP obtained in this work are 6.2 and 3.5 nM, respectively. PMID:26433068

  2. Ion adsorption on the inner surface of single-walled carbon nanotubes used as electrodes for electric double-layer capacitors.

    Science.gov (United States)

    Al-zubaidi, Ayar; Inoue, Tsuyoshi; Matsushita, Tomohiro; Ishii, Yosuke; Kawasaki, Shinji

    2012-12-14

    In the present study, ion adsorption on the outer and inner surfaces of single-walled carbon nanotubes (SWCNTs) in different aqueous and organic electrolytes was analysed. It was found that the fundamental properties of tube size and electronic structure, particularly the transition between van Hove singularities (the band gap), reflected by the shape of the cyclic voltammogram and increase in the number of charge carriers upon doping, apparently provided additional energy for ion adsorption inside open-end SWCNTs. In addition, when cyclic voltammograms recorded at different potential scan rates were observed, the outer surface of the tubes demonstrated the behaviour of a flat electrode with less dependence on the potential scan rate when compared to the inner surface, which acts as a porous electrode showing an ohmic drop and a distorted voltammogram at high scan rates. Mathematical analysis showed that opening the inner channel of the tubes increases electrode resistance, and that the magnitude of variation in the resistance depends on the type of electrolyte. PMID:23108533

  3. Second order advantage obtained by spectroelectrochemistry along with novel carbon nanotube modified mesh electrode: Application for determination of acetaminophen in Novafen samples

    Science.gov (United States)

    Asadpour-Zeynali, Karim; Maryam Sajjadi, S.; Taherzadeh, Fatemeh

    2016-01-01

    A matrix-augmentation multivariate curve resolution-alternating least-squares (MA-MCR-ALS) has been conducted on the spectroelectrochemical data of acetaminophen oxidation in order to quantify acetaminophen in Novafen capsule in the presence of unknown interferences. The experiments were carried out using new cheap mesh electrode, namely carbon nanotube modified mesh electrode (CNMME) as optically transparent thin layer electrode (OTTLE). For each sample, a second order spectroelectrochemical data was obtained and MA-MCR-ALS method was applied to analyze these data. Unlike full trilinear models such as PARAFAC, MCR-ALS is flexible in applying trilinearity constraint for each component, a fact which makes it manage deviations from trilinearity of data effectively. This method was employed in both spectral and kinetic augmentation mode of data under examining different trilinear components. However, spectral augmentation was the only setting which allows MA-MCR-ALS to solve the analytical problem achieving the second order advantage. Therefore, here the results of the augmentation in this mode have been described. In order to obtain the best analytical figures of merit in the analysis, different constraints were investigated. The results indicated the accuracy of the proposed method.

  4. Lithium ion batteries made of electrodes with 99 wt% active materials and 1 wt% carbon nanotubes without binder or metal foils

    Science.gov (United States)

    Hasegawa, Kei; Noda, Suguru

    2016-07-01

    Herein, we propose lithium ion batteries (LIBs) without binder or metal foils, based on a three-dimensional carbon nanotube (CNT) current collector. Because metal foils occupy 20-30 wt% of conventional LIBs and the polymer binder has no electrical conductivity, replacing such non-capacitive materials is a valid approach for improving the energy and power density of LIBs. Adding only 1 wt% of few-wall CNTs to the active material enables flexible freestanding sheets to be fabricated by simple dispersion and filtration processes. Coin cell tests are conducted on full cells fabricated from a 99 wt% LiCoO2-1 wt% CNT cathode and 99 wt% graphite-1 wt% CNT anode. Discharge capacities of 353 and 306 mAh ggraphite-1 are obtained at charge-discharge rates of 37.2 and 372 mA ggraphite-1, respectively, with a capacity retention of 65% at the 500th cycle. The suitability of the 1 wt% CNT-based composite electrodes for practical scale devices is demonstrated with laminate cells containing 50 × 50 mm2 electrodes. Use of metal combs instead of metal foils enables charge-discharge operation of the laminate cell without considerable IR drop. Such electrodes will minimize the amount of metal and maximize the amount of active materials contained in LIBs.

  5. Carbon nanotubes: synthesis and functionalization

    OpenAIRE

    Andrews, Robert

    2007-01-01

    This thesis focuses on two of the major challenges of carbon nanotube (CNT) research: understanding the growth mechanism of nanotubes by chemical vapour deposition (CVD) and the positioning of nanotubes on surfaces. The mechanism of growth of single–walled nanotubes (SWNTs) has been studied in two ways. Firstly, a novel iron nanoparticle catalyst for the production of single–walled nanotubes was developed. CVD conditions were established that produced high quality tubes. These optimised C...

  6. Glucose sensing electrodes based on a poly(3,4-ethylenedioxythiophene)/Prussian blue bilayer and multi-walled carbon nanotubes.

    Science.gov (United States)

    Chiu, Jing-Yang; Yu, Chung-Mu; Yen, Miao-Ju; Chen, Lin-Chi

    2009-03-15

    Here we report a new glucose sensing electrode based on a poly(3,4-ethylenedioxythiophene) (PEDOT)/Prussian blue (PB) bilayer and multi-walled carbon nanotubes (CNT). The bilayer was prepared on a flexible screen-printed carbon electrode (SPCE) by sequential electrodeposition. The inner PB layer was electrodeposited first for detecting H(2)O(2) from glucose oxidation; the outer PEDOT layer was electropolymerized on a baked or an unbaked PB film to entrap glucose oxidase (GOD). It was observed that the stability of PB in phosphate buffered saline (pH 7.4) was attained by post-deposition bake at 100 degrees C and the outer PEDOT layer both. In addition, a baked PB film enhanced the subsequent PEDOT growth and the corresponding GOD entrapment. As a result, the bilayer enzyme electrode showed highly resolved and reproducible signals (R.S.D.=2.54%) to glucose samples from 100 microM to 1M during a flow-injection analysis (FIA) at -0.1V vs. Ag/AgCl. The sensitivity of the linear range (1-10mM) was 2.67 microAcm(-2)mM(-1). Moreover, the electrode retained ca. 82% of the original response after 1-month storage in PBS, pH 6.0 at 4 degrees C and could determine the glucose level in human serum precisely. Besides, it was found that CNT incorporation could further improve the sensitivity and could achieve muM-range glucose detection. PMID:19042119

  7. Mn3O4 anchored on carbon nanotubes as an electrode reaction catalyst of V(IV)/V(V) couple for vanadium redox flow batteries

    International Nuclear Information System (INIS)

    Highlights: • Mn3O4/MWCNTs (multi-walled carbon nanotubes) composite fabricated by a simple solvothermal method was developed as electrochemical catalyst of V(IV)/V(V) redox couple for vanadium redox flow batteries for the first time. • The electrocatalytic kinetics of the redox reactions of three electrocatalysts (pure Mn3O4, pure MWCNTs, Mn3O4/MWCNTs) were compared, and were in the order of Mn3O4/MWCNTs > MWCNTs > Mn3O4. • The cell using Mn3O4/MWCNTs has lower electrochemical polarization, with larger discharge capacity and energy efficiency. The average energy efficiency of the cell using Mn3O4/MWCNTs is 84.65%, 3.73% higher than that of the pristine cell. - Abstract: Mn3O4/MWCNTs (multi-walled carbon nanotubes) composite fabricated by a simple solvothermal method was developed as electrochemical catalyst of V(IV)/V(V) redox couple for vanadium redox flow batteries. The electrochemical activity of V(IV)/V(V) redox couple can be enhanced by the electrochemical catalysts (Mn3O4, MWCNTs, Mn3O4/MWCNTs), and the electrocatalytic kinetics of the redox reactions were in the order of Mn3O4/MWCNTs > MWCNTs > Mn3O4. The cell using Mn3O4/MWCNTs composite as electrochemical catalyst was assembled and the charge-discharge performance was evaluated. Compared with the pristine cell, the cell using positive graphite felt modified by Mn3O4/MWCNTs had lower electrochemical polarization, larger discharge capacity and energy efficiency. The average energy efficiency of the cell using modified positive electrode for 50 cycles was 84.65%, 3.73% higher than that of the pristine cell. The superior electrocatalytic performance of Mn3O4/MWCNTs composite was mainly due to the effective mixed conducting network, facilitating the electron transport and ion diffusion in the electrode/electrolyte interface

  8. An electrochemical sensor for warfarin determination based on covalent immobilization of quantum dots onto carboxylated multiwalled carbon nanotubes and chitosan composite film modified electrode

    International Nuclear Information System (INIS)

    A method is described for the construction of a novel electrochemical warfarin sensor based on covalent immobilization of CdS-quantum dots (CdS-QDs) onto carboxylated multiwalled carbon nanotubes/chitosan (CS) composite film on the surface of a glassy carbon electrode. The CdS-QDs/CS/MWCNTs were characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infra-red (FTIR) spectroscopy, XRD analysis and electrochemical impedance spectroscopy (EIS). The sensor showed optimum anodic stripping response within 90 s at an accumulation potential of 0.75 V. The modified electrode was used to detect the concentration of warfarin with a wide linear range of 0.05–80 μM and a detection limit (S/N = 3) of 8.5 nM. The proposed sensor has good storage stability, repeatability and reproducibility and was successfully applied for the determination of warfarin in real samples such as urine, serum and milk. - Highlights: • A new sensitive sensor for warfarin determination was developed. • The sensor was constructed based on covalent immobilization of CdS-QDs on the chitosan/MWCNTs/GCE. • The parameters affecting the stripping analysis of warfarin were optimized. • The proposed sensor is used for trace determination of warfarin in urine, serum and milk

  9. An electrochemical sensor for warfarin determination based on covalent immobilization of quantum dots onto carboxylated multiwalled carbon nanotubes and chitosan composite film modified electrode

    Energy Technology Data Exchange (ETDEWEB)

    Gholivand, Mohammad Bagher, E-mail: mbgholivand2013@gmail.com; Mohammadi-Behzad, Leila

    2015-12-01

    A method is described for the construction of a novel electrochemical warfarin sensor based on covalent immobilization of CdS-quantum dots (CdS-QDs) onto carboxylated multiwalled carbon nanotubes/chitosan (CS) composite film on the surface of a glassy carbon electrode. The CdS-QDs/CS/MWCNTs were characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infra-red (FTIR) spectroscopy, XRD analysis and electrochemical impedance spectroscopy (EIS). The sensor showed optimum anodic stripping response within 90 s at an accumulation potential of 0.75 V. The modified electrode was used to detect the concentration of warfarin with a wide linear range of 0.05–80 μM and a detection limit (S/N = 3) of 8.5 nM. The proposed sensor has good storage stability, repeatability and reproducibility and was successfully applied for the determination of warfarin in real samples such as urine, serum and milk. - Highlights: • A new sensitive sensor for warfarin determination was developed. • The sensor was constructed based on covalent immobilization of CdS-QDs on the chitosan/MWCNTs/GCE. • The parameters affecting the stripping analysis of warfarin were optimized. • The proposed sensor is used for trace determination of warfarin in urine, serum and milk.

  10. Voltammetric behavior of 3,5-dinitrobenzoic acid in solution on GCE and encapsulated on multiwalled carbon nanotube modified electrode

    OpenAIRE

    Moscoso, R.; Carbajo Timoteo, José Coronada; Mozo Llamazares, Juan Daniel; Squella Serrano, Juan Arturo

    2016-01-01

    The cyclic voltammetric behavior of 3,5-dinitrobenzoic acid (3,5-DNB) in 0.1 M PBS of pH 7 was examined at a glassy carbon electrode (GCE). 3,5-DNB was found to produce two irreversible reduction peaks corresponds to the reduction of each nitro group in the 3,5-DNB molecule. Our results contradict previous studies (P.Gopal et al. Journal of Molecular Liquids 178 (2013) 168-174) wherein the same peaks are assigned as, the first, to the reduction of the nitro group to hydroxylami...

  11. An amperometric biosensor based on acetylcholinesterase immobilized onto iron oxide nanoparticles/multi-walled carbon nanotubes modified gold electrode for measurement of organophosphorus insecticides

    International Nuclear Information System (INIS)

    Graphical abstract: The stepwise amperometric biosensor fabrication process and immobilized acetylcholinesterase inhibition in pesticide solution. Highlights: · Constructed a novel composite material using Fe3O4NP and c-MWCNT at Au electrode for electrocatalysis. · The properties of nanoparticles modified electrodes were studied by SEM, FTIR, CVs and EIS. · The biosensor exhibited good sensitivity (0.475 mA μM-1) · The half life of electrode was 2 months. · The sensor was suitable for trace detection of OP pesticide residues in milk and water. - Abstract: An acetylcholinesterase (AChE) purified from maize seedlings was immobilized covalently onto iron oxide nanoparticles (Fe3O4NP) and carboxylated multi walled carbon nanotubes (c-MWCNT) modified Au electrode. An organophosphorus (OP) biosensor was fabricated using this AChE/Fe3O4/c-MWCNT/Au electrode as a working electrode, Ag/AgCl as standard and Pt wire as an auxiliary electrode connected through a potentiostat. The biosensor was based on inhibition of AChE by OP compounds/insecticides. The properties of nanoparticles modified electrodes were studied by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), cyclic voltammograms (CVs) and electrochemical impedance spectroscopy (EIS). The synergistic action of Fe3O4NP and c-MWCNT showed excellent electrocatalytic activity at low potential (+0.4 V). The optimum working conditions for the sensor were pH 7.5, 35 deg. C, 600 μM substrate concentration and 10 min for inhibition by pesticide. Under optimum conditions, the inhibition rates of OP pesticides were proportional to their concentrations in the range of 0.1-40 nM, 0.1-50 nM, 1-50 nM and 10-100 nM for malathion, chlorpyrifos, monocrotophos and endosulfan respectively. The detection limits were 0.1 nM for malathion and chlorpyrifos, 1 nM for monocrotophos and 10 nM for endosulfan. The biosensor exhibited good sensitivity (0.475 mA μM-1), reusability (more than 50 times) and stability (2

  12. An amperometric biosensor based on acetylcholinesterase immobilized onto iron oxide nanoparticles/multi-walled carbon nanotubes modified gold electrode for measurement of organophosphorus insecticides

    Energy Technology Data Exchange (ETDEWEB)

    Chauhan, Nidhi [Department of Biochemistry, M.D. University, Rohtak 124001, Haryana (India); Pundir, Chandra Shekhar, E-mail: pundircs@rediffmail.com [Department of Biochemistry, M.D. University, Rohtak 124001, Haryana (India)

    2011-09-02

    Graphical abstract: The stepwise amperometric biosensor fabrication process and immobilized acetylcholinesterase inhibition in pesticide solution. Highlights: {center_dot} Constructed a novel composite material using Fe{sub 3}O{sub 4}NP and c-MWCNT at Au electrode for electrocatalysis. {center_dot} The properties of nanoparticles modified electrodes were studied by SEM, FTIR, CVs and EIS. {center_dot} The biosensor exhibited good sensitivity (0.475 mA {mu}M{sup -1}) {center_dot} The half life of electrode was 2 months. {center_dot} The sensor was suitable for trace detection of OP pesticide residues in milk and water. - Abstract: An acetylcholinesterase (AChE) purified from maize seedlings was immobilized covalently onto iron oxide nanoparticles (Fe{sub 3}O{sub 4}NP) and carboxylated multi walled carbon nanotubes (c-MWCNT) modified Au electrode. An organophosphorus (OP) biosensor was fabricated using this AChE/Fe{sub 3}O{sub 4}/c-MWCNT/Au electrode as a working electrode, Ag/AgCl as standard and Pt wire as an auxiliary electrode connected through a potentiostat. The biosensor was based on inhibition of AChE by OP compounds/insecticides. The properties of nanoparticles modified electrodes were studied by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), cyclic voltammograms (CVs) and electrochemical impedance spectroscopy (EIS). The synergistic action of Fe{sub 3}O{sub 4}NP and c-MWCNT showed excellent electrocatalytic activity at low potential (+0.4 V). The optimum working conditions for the sensor were pH 7.5, 35 deg. C, 600 {mu}M substrate concentration and 10 min for inhibition by pesticide. Under optimum conditions, the inhibition rates of OP pesticides were proportional to their concentrations in the range of 0.1-40 nM, 0.1-50 nM, 1-50 nM and 10-100 nM for malathion, chlorpyrifos, monocrotophos and endosulfan respectively. The detection limits were 0.1 nM for malathion and chlorpyrifos, 1 nM for monocrotophos and 10 nM for endosulfan. The

  13. Studies on electrochemical behaviour on NpO22+/NpO2+ redox couple at single walled carbon nanotube modified glassy carbon electrode (SWCNT-GC)

    International Nuclear Information System (INIS)

    Electrochemistry of NpO22+/NpO2+ couple in 1 M H2SO4 was studied on bare and modified glassy carbon (GC) electrodes by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The modified electrode (SWCNTs-GC) was characterized by scanning electron microscopy (SEM). Electrocatalysis of NpO22+/NpO2+ redox reaction was observed on SWCNT-GC electrode. The lower charge transfer resistance at SWCNT-GC reflects faster rate of electron transfer reaction of Np(VI)/Np(V) couple. These results are interesting to develop electroanalytical methodologies for neptunium determination using SWCNT modified electrode. To the best of our knowledge, this is the first study on the electrocatalysis of neptunium on SWCNT modified electrode.

  14. Formation of a robust and stable film comprising ionic liquid and polyoxometalate on glassy carbon electrode modified with multiwalled carbon nanotubes: Toward sensitive and fast detection of hydrogen peroxide and iodate

    International Nuclear Information System (INIS)

    A robust and stable film comprising n-octylpyridinum hexafluorophosphate ([C8Py][PF6]) and 1:12 phosphomolybdic acid (PMo12) was prepared on glassy carbon electrodes modified with multiwall carbon nanotubes (GCE/MWCNTs) by dip-coating. The cyclic voltammograms of the GCE/MWCNTs/[C8Py][PF6]-PMo12 showed three well-defined pairs of redox peaks due to the PMo12 system. The surface coverage for the immobilized PMo12 and the average values of the electron transfer rate constant for three pairs of redox peaks were evaluated. The GCE/MWCNTs/[C8Py][PF6]-PMo12 showed great electrocatalytic activity towards the reduction of H2O2 and iodate. The kinetic parameters of the catalytic reduction of hydrogen peroxide and iodate at the electrode surface and analytical features of the sensor for amperometric determination of hydrogen peroxide and iodate were evaluated.

  15. A glassy carbon electrode modified with the nickel(II)-bis(1,10-phenanthroline) complex and multi-walled carbon nanotubes, and its use as a sensor for ascorbic acid

    International Nuclear Information System (INIS)

    A glassy carbon electrode (GCE) was modified with the nickel(II)-bis(1,10-phenanthroline) complex and with multi-walled carbon nanotubes (MWCNTs). The nickel complex was electrodeposited on the MWCNTs by cyclic voltammetry. The modified GCE displays excellent electrocatalytic activity to the oxidation of ascorbic acid (AA). The effects of fraction of MWCNTs, film thickness and pH values were optimized. Response to AA is linear in the 10 to 630 μM concentration range, and the detection limit is 4 μM (at a signal-to-noise ratio of 3:1). The modified electrode was applied to determine AA in vitamin C tablets and in spiked fruit juice. (author)

  16. Selective Deposition and Alignment of Single-Walled Carbon Nanotubes Assisted by Dielectrophoresis: From Thin Films to Individual Nanotubes

    OpenAIRE

    Li Pengfei; Xue Wei

    2010-01-01

    Abstract Dielectrophoresis has been used in the controlled deposition of single-walled carbon nanotubes (SWNTs) with the focus on the alignment of nanotube thin films and their applications in the last decade. In this paper, we extend the research from the selective deposition of SWNT thin films to the alignment of small nanotube bundles and individual nanotubes. Electrodes with “teeth”-like patterns are fabricated to study the influence of the electrode width on the deposition an...

  17. Fast Electromechanical Switches Based on Carbon Nanotubes

    Science.gov (United States)

    Kaul, Anupama; Wong, Eric; Epp, Larry

    2008-01-01

    Electrostatically actuated nanoelectromechanical switches based on carbon nanotubes have been fabricated and tested in a continuing effort to develop high-speed switches for a variety of stationary and portable electronic equipment. As explained below, these devices offer advantages over electrostatically actuated microelectromechanical switches, which, heretofore, have represented the state of the art of rapid, highly miniaturized electromechanical switches. Potential applications for these devices include computer memories, cellular telephones, communication networks, scientific instrumentation, and general radiation-hard electronic equipment. A representative device of the present type includes a single-wall carbon nanotube suspended over a trench about 130 nm wide and 20 nm deep in an electrically insulating material. The ends of the carbon nanotube are connected to metal electrodes, denoted the source and drain electrodes. At bottom of the trench is another metal electrode, denoted the pull electrode (see figure). In the off or open switch state, no voltage is applied, and the nanotube remains out of contact with the pull electrode. When a sufficiently large electric potential (switching potential) is applied between the pull electrode and either or both of the source and drain electrodes, the resulting electrostatic attraction bends and stretches the nanotube into contact with the pull electrode, thereby putting the switch into the "on" or "closed" state, in which substantial current (typically as much as hundreds of nanoamperes) is conducted. Devices of this type for use in initial experiments were fabricated on a thermally oxidized Si wafer, onto which Nb was sputter-deposited for use as the pull-electrode layer. Nb was chosen because its refractory nature would enable it to withstand the chemical and thermal conditions to be subsequently imposed for growing carbon nanotubes. A 200- nm-thick layer of SiO2 was formed on top of the Nb layer by plasma

  18. Synthesis of carbon nanotubes over 3D cubical Co-KIT-6 and nickel decorated graphene by Hummer's method, its application as counter electrode in dye sensitive solar cell

    Science.gov (United States)

    Subramanian, Sunu; Pandurangan, Arumugam

    2016-04-01

    The challenges on carbon nanotubes and graphene are still the subject of many research works due to its unique properties. There are three main methods to synthesis carbon nanotubes in which chemical vapor deposition (CVD) method can use for large scale production. The principle of CVD is the decomposition of various hydrocarbons over transition metal supported catalyst. KIT-6 molecular sieve was used as a support to prepare cobalt catalyst for CVD method using metal impregnation method to produce cobalt loadings of 2, 4 and 6 wt%. The catalysts were characterized by XRD, FTIR &TEM. Carbon nanotubes (CNTs) synthesized on Co-KIT-6 was also characterized by XRD, TGA, SEM & Raman spectra. Graphene was synthesized by Hummers method, which is the most common method for preparing graphene oxide. Graphene oxide was prepared by oxidation of graphite using some oxidizing agents like sulphuric acid, sodium nitrate and potassium permanganate. This graphene oxide is further treated with hydrazine solution to convert it into chemically converted graphene and also decorated with nickel metal and characterized. Hummer's method is important for large scale production of graphene. Both Graphene and carbon nanotubes are used in different fields due to its unique properties. Both Graphene and carbon nanotubes are fabricated in counter electrode of Dye sensitized solar cells (DSSC). By cyclic voltammetry study, it confirms that both materials are good and efficient to replace platinum in the DSSC.

  19. Insights into the surface and redox properties of single-walled carbon nanotube-cobalt(II) tetra-aminophthalocyanine self-assembled on gold electrode

    Energy Technology Data Exchange (ETDEWEB)

    Ozoemena, Kenneth I. [Chemistry Department, University of Pretoria, Pretoria 0002 (South Africa)]. E-mail: kenneth.ozoemena@up.ac.za; Nyokong, Tebello [Chemistry Department, Rhodes University, Grahamstown 6140 (South Africa); Nkosi, Duduzile [Chemistry Department, University of Pretoria, Pretoria 0002 (South Africa); Chambrier, Isabelle [School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich, Norfolk NR4 7TJ (United Kingdom); Cook, Michael J. [School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich, Norfolk NR4 7TJ (United Kingdom)

    2007-03-10

    This paper describes for the first time the electrochemical properties of redox-active self-assembled films of single-walled carbon nanotubes (SWCNTs) coordinated to cobalt(II)tetra-aminophthalocyanine (CoTAPc) by sequential self-assembly onto a preformed aminoethanethiol (AET) self-assembled monolayer (SAM) on a gold electrode. Both redox-active SAMs (Au-AET-SWCNT and Au-AET-SWCNT-CoTAPc) exhibited reversible electrochemistry in aqueous (phosphate buffer) solution. X-ray photoelectron spectroscopy (XPS) confirmed the appearance on the gold surface of the various elements found on the SAMs. Atomic force microscopy (AFM) images prove, corroborating the estimated electrochemical surface concentrations, that these SAMs lie normal to the gold surface. Electrochemical impedance spectroscopy (EIS) analyses in the presence of [Fe(CN){sub 6}]{sup 3-/4-} as a redox probe revealed that the Au-AET-SWCNT-CoTAPc showed much lower ({approx}10 times) electron-transfer resistance (R {sub et}) and much higher ({approx}10 times) apparent electron-transfer rate constant (k {sub app}) compared to the Au-AET-SWCNT SAM. Interestingly, a preliminary electrocatalytic investigation showed that both SAMs exhibit comparable electrocatalytic responses towards the detection of dopamine in pH 7.4 phosphate buffer solutions (PBS). The electrochemical studies (cyclic voltammetry (CV) and EIS) prove that SWCNT greatly improves the electronic communication between CoTAPc and the Au electrode surface.

  20. Insights into the surface and redox properties of single-walled carbon nanotube-cobalt(II) tetra-aminophthalocyanine self-assembled on gold electrode

    International Nuclear Information System (INIS)

    This paper describes for the first time the electrochemical properties of redox-active self-assembled films of single-walled carbon nanotubes (SWCNTs) coordinated to cobalt(II)tetra-aminophthalocyanine (CoTAPc) by sequential self-assembly onto a preformed aminoethanethiol (AET) self-assembled monolayer (SAM) on a gold electrode. Both redox-active SAMs (Au-AET-SWCNT and Au-AET-SWCNT-CoTAPc) exhibited reversible electrochemistry in aqueous (phosphate buffer) solution. X-ray photoelectron spectroscopy (XPS) confirmed the appearance on the gold surface of the various elements found on the SAMs. Atomic force microscopy (AFM) images prove, corroborating the estimated electrochemical surface concentrations, that these SAMs lie normal to the gold surface. Electrochemical impedance spectroscopy (EIS) analyses in the presence of [Fe(CN)6]3-/4- as a redox probe revealed that the Au-AET-SWCNT-CoTAPc showed much lower (∼10 times) electron-transfer resistance (R et) and much higher (∼10 times) apparent electron-transfer rate constant (k app) compared to the Au-AET-SWCNT SAM. Interestingly, a preliminary electrocatalytic investigation showed that both SAMs exhibit comparable electrocatalytic responses towards the detection of dopamine in pH 7.4 phosphate buffer solutions (PBS). The electrochemical studies (cyclic voltammetry (CV) and EIS) prove that SWCNT greatly improves the electronic communication between CoTAPc and the Au electrode surface

  1. A third-generation biosensor for hydrogen peroxide based on the immobilization of horseradish peroxidase on a disposable carbon nanotubes modified screen–printed electrode

    International Nuclear Information System (INIS)

    A screen-printed carbon nanotube (CNTs) based disposable third generation biosensor for hydrogen peroxide (H2O2) was constructed by mixing CNTs with a cellulose acetate binder on an epoxy substrate. The surface was covered with a layer consisting of horseradish peroxidase (HRP) crosslinked to bovine serum albumin with glutaraldehyde. The CNTs acted as both the electrode material and charge promoter to facilitate the direct electron transfer between immobilized HRP and the modified electrode. At a working potential of −300 mV (vs. Ag/AgCl), the biosensor displays an excellent electrocatalytic response to the reduction of H2O2 without the aid of a mediator. It has a fast (3 s) amperometric response and a linear calibration in the concentration range 0.005–0.1 mmol L−1, with a 0.85 μM detection limit (at an S/N of 3). The biosensor can be easily produced, is stable and reproducible. (author)

  2. Laccase electrodes based on the combination of single-walled carbon nanotubes and redox layered double hydroxides: Towards the development of biocathode for biofuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Shou-Nian; Holzinger, Michael; Cosnier, Serge [Departement de Chimie Moleculaire UMR-5250, ICMG FR-2607, CNRS Universite Joseph Fourier, BP-53, 38041 Grenoble Cedex 9 (France); Mousty, Christine [Laboratoire des Materiaux Inorganiques, Universite Blaise Pascal, CNRS UMR-6002, 63177 Aubiere Cedex (France)

    2010-08-01

    Single-walled carbon nanotubes (SWCNT) were combined with layered double hydroxides (LDH) intercalated with 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) diammonium salt [ZnCr-ABTS] to entrap and electrically connect laccase enzyme. The resulting laccase electrodes exhibited an electro-enzymatic activity for O{sub 2} reduction. To improve this electrocatalytic activity, varying SWCNT quantities and loading methods were tested to optimize the configuration of the laccase electrodes. Furthermore, the resulting bioelectrode was successfully used as a biocathode for the elaboration of a membrane-less glucose/air biofuel cell. In 0.1 M phosphate buffer (PBS) of pH 6.0, containing glucose (5 mM) under ambient conditions, the assembled biofuel cell yielded a maximum power density of 18 {mu}W cm{sup -2} at a cell voltage of 0.3 V whereas this power decreased to 8.3 {mu}W cm{sup -2} for a biofuel cell based on the identical biocathode setup without SWCNT. (author)

  3. Synthesis of nano-sized cyanide ion-imprinted polymer via non-covalent approach and its use for the fabrication of a CN(-)-selective carbon nanotube impregnated carbon paste electrode.

    Science.gov (United States)

    Alizadeh, Taher; Sabzi, Reza Emamali; Alizadeh, Hassan

    2016-01-15

    Nano-sized CN(-)-imprinted polymer was synthesized by the copolymerization of methyl methacrylic acid (MAA), vinyl pyridine (VP) and ethylene glycol dimethacrylate in the presence of cyanide ion. The obtained polymeric nanoparticles were incorporated with carbon paste electrode (CPE) to produce a CN(-)-selective electrode. Functional monomer kind had crucial influence on the efficiency of the sensor. The presence of both VP and MAA in the structure of the imprinted polymer improved the sensing characteristics of the electrode. Also, the mole ratio of MAA/VP, cross-liker kind, cross-linker amount, solvent kind and amount were found to be effective factors in the electrode behavior. Presence of little amount of multi-walled carbon nanotubes (MWCNTs) in the CPE improved the detection range and response time of the electrode at the expense of small decrease in Nernstian slope. The electrode, containing CN(-)-imprinted polymer and MWCNTs showed a dynamic linear range of 1×10(-6)-1×10(-1)mol L(-1), Nernstian slope of 46.3±(0.6) mV and detection limit of 7.5×10(-7)mol L(-1); whereas, the same electrode in the absence of MWCNTs led to linear range, Nernstian slope and detection limit of 1×10(-5)-1×10(-1)molL(-1), 55.3±(0.7) mV and 8×10(-6)mol L(-1), respectively. The utility of the electrodes was checked by determination of cyanide ion in some real samples. PMID:26592581

  4. Carbon Nanotube Electron Emitter for X-ray Imaging

    Directory of Open Access Journals (Sweden)

    Jung Su Kang

    2012-11-01

    Full Text Available The carbon nanotube field emitter array was grown on silicon substrate through a resist-assisted patterning (RAP process. The shape of the carbon nanotube array is elliptical with 2.0 × 0.5 mm2 for an isotropic focal spot size at anode target. The field emission properties with triode electrodes show a gate turn-on field of 3 V/µm at an anode emission current of 0.1 mA. The author demonstrated the X-ray source with triode electrode structure utilizing the carbon nanotube emitter, and the transmitted X-ray image was of high resolution.

  5. Carbon Nanotube Electron Emitter for X-ray Imaging

    OpenAIRE

    Jung Su Kang; Je Hwang Ryu; Kyu Chang Park

    2012-01-01

    The carbon nanotube field emitter array was grown on silicon substrate through a resist-assisted patterning (RAP) process. The shape of the carbon nanotube array is elliptical with 2.0 × 0.5 mm2 for an isotropic focal spot size at anode target. The field emission properties with triode electrodes show a gate turn-on field of 3 V/µm at an anode emission current of 0.1 mA. The author demonstrated the X-ray source with triode electrode structure utilizing the carbon nanotube em...

  6. Carbon nanotube network varactor

    International Nuclear Information System (INIS)

    Microelectromechanical system (MEMS) varactors based on a freestanding layer of single-walled carbon nanotube (SWCNT) films were designed, fabricated and tested. The freestanding SWCNT film was employed as a movable upper patch in the parallel plate capacitor of the MEMS. The measurements of the SWCNT varactors show very high tunability, nearly 100%, of the capacitance with a low actuation voltage of 10 V. The functionality of the varactor is improved by implementing a flexible nanocellulose aerogel filling. (paper)

  7. Carbon nanotube network varactor

    Science.gov (United States)

    Generalov, A. A.; Anoshkin, I. V.; Erdmanis, M.; Lioubtchenko, D. V.; Ovchinnikov, V.; Nasibulin, A. G.; Räisänen, A. V.

    2015-01-01

    Microelectromechanical system (MEMS) varactors based on a freestanding layer of single-walled carbon nanotube (SWCNT) films were designed, fabricated and tested. The freestanding SWCNT film was employed as a movable upper patch in the parallel plate capacitor of the MEMS. The measurements of the SWCNT varactors show very high tunability, nearly 100%, of the capacitance with a low actuation voltage of 10 V. The functionality of the varactor is improved by implementing a flexible nanocellulose aerogel filling.

  8. Carbon nanotube IR detectors (SV)

    Energy Technology Data Exchange (ETDEWEB)

    Leonard, F. L.

    2012-03-01

    Sandia National Laboratories (Sandia) and Lockheed Martin Corporation (LMC) collaborated to (1) evaluate the potential of carbon nanotubes as channels in infrared (IR) photodetectors; (2) assemble and characterize carbon nanotube electronic devices and measure the photocurrent generated when exposed to infrared light;(3) compare the performance of the carbon nanotube devices with that of traditional devices; and (4) develop and numerically implement models of electronic transport and opto-electronic behavior of carbon nanotube infrared detectors. This work established a new paradigm for photodetectors.

  9. From Carbon Nanotube Crystals to Carbon Nanotube Flowers

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhengjun; ZHAO Ye; ZHOU Ya

    2005-01-01

    We have investigated the very initial deposition stages of chemical vapor deposition (CVD) with ferrocene (Fe(C5H5)2) and xylene (C8H10) for growing carbon nanotubes, and made clear that the mechanism for the self-organization behaviors of nanotubes at different growth stages by this approach. For instance, the organization of nanotubes into flower-like structures at prolonged deposition is developed from the crystal-like structures formed at early growth stages, both of which are closely related to and determined by the very initial deposition stages of this CVD approach. Based on this approach, ways have been established to build up different architectures of carbon nanotubes, by controlling the initial deposition stages of the CVD process, with which we have realized the selective growth of self-organized carbon nanotube structures. This study provides a new idea for growing carbon nanotube architectures by CVD.

  10. Co@Co3O4 Encapsulated in Carbon Nanotube-Grafted Nitrogen-Doped Carbon Polyhedra as an Advanced Bifunctional Oxygen Electrode.

    Science.gov (United States)

    Aijaz, Arshad; Masa, Justus; Rösler, Christoph; Xia, Wei; Weide, Philipp; Botz, Alexander J R; Fischer, Roland A; Schuhmann, Wolfgang; Muhler, Martin

    2016-03-14

    Efficient reversible oxygen electrodes for both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) are vitally important for various energy conversion devices, such as regenerative fuel cells and metal-air batteries. However, realization of such electrodes is impeded by insufficient activity and instability of electrocatalysts for both water splitting and oxygen reduction. We report highly active bifunctional electrocatalysts for oxygen electrodes comprising core-shell Co@Co3O4 nanoparticles embedded in CNT-grafted N-doped carbon-polyhedra obtained by the pyrolysis of cobalt metal-organic framework (ZIF-67) in a reductive H2 atmosphere and subsequent controlled oxidative calcination. The catalysts afford 0.85 V reversible overvoltage in 0.1 m KOH, surpassing Pt/C, IrO2 , and RuO2 and thus ranking them among one of the best non-precious-metal electrocatalysts for reversible oxygen electrodes. PMID:26913583

  11. Carbon nanotube core graphitic shell hybrid fibers.

    Science.gov (United States)

    Hahm, Myung Gwan; Lee, Jae-Hwang; Hart, Amelia H C; Song, Sung Moo; Nam, Jaewook; Jung, Hyun Young; Hashim, Daniel Paul; Li, Bo; Narayanan, Tharangattu N; Park, Chi-Dong; Zhao, Yao; Vajtai, Robert; Kim, Yoong Ahm; Hayashi, Takuya; Ku, Bon-Cheol; Endo, Morinobu; Barrera, Enrique; Jung, Yung Joon; Thomas, Edwin L; Ajayan, Pulickel M

    2013-12-23

    A carbon nanotube yarn core graphitic shell hybrid fiber was fabricated via facile heat treatment of epoxy-based negative photoresist (SU-8) on carbon nanotube yarn. The effective encapsulation of carbon nanotube yarn in carbon fiber and a glassy carbon outer shell determines their physical properties. The higher electrical conductivity (than carbon fiber) of the carbon nanotube yarn overcomes the drawbacks of carbon fiber/glassy carbon, and the better properties (than carbon nanotubes) of the carbon fiber/glassy carbon make up for the lower thermal and mechanical properties of the carbon nanotube yarn via synergistic hybridization without any chemical doping and additional processes. PMID:24224730

  12. Simultaneous detection of ascorbic acid, dopamine, uric acid and tryptophan with Azure A-interlinked multi-walled carbon nanotube/gold nanoparticles composite modified electrode

    OpenAIRE

    Hayati Filik; Asiye Aslıhan Avan; Sevda Aydar

    2016-01-01

    In this paper, multi-walled carbon nanotube/Azure A/gold nanoparticle composites (Nafion/AuNPs/AzA/MWCNTs) were prepared by binding gold nanoparticles to the surfaces of Azure A-coated carbon nanotubes. Nafion/AuNPs/AzA/MWCNTs based electrochemical sensor was fabricated for the simultaneous determination of ascorbic acid, dopamine, uric acid, and tryptophan. Cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the electrochemical properties of the modified e...

  13. A glassy carbon electrode modified with bismuth nanotubes in a silsesquioxane framework for sensing of trace lead and cadmium by stripping voltammetry

    International Nuclear Information System (INIS)

    Single-walled bismuth nanotubes (sw-BiNTs) were self-assembled with octa(3-aminopropyl) silsesquioxane as a framework and to govern morphology. Deposited on a glassy carbon electrode (GCE), the sw-BiNTs were used for the simultaneous analysis of Pb(II) and Cd(II) by square wave stripping voltammetry. The sw-BiNTs were prepared by (a) coordination interaction between the amino groups of the silsesquioxane and the Bi(III) ions, and by (b) reduction with sodium borohydride. Transmission electron microscopy images revealed single-walled tubular structures with diameters of ∼4–6 nm, and with lengths of several hundreds nanometers. GCEs modified with such sw-BiNTs perform much better than bare GCEs in stripping analysis of Pb(II) and Cd(II). The effects of adsorption quantity of sw-BiNTs, solution pH, pulse amplitude, and pulse width were optimized. The modified electrode was then used for the analysis of Pb(II) and Cd(II) in a linear response range from 0.4 to 6 μM with a sensitivity of 4.692 μA μM−1 and 3.835 μA μM−1, and detection limits of 1 nM and 5 nM, respectively. The method was successfully applied to the analysis of Pb(II) and Cd(II) in toy leachates, and the results were in good agreement with those obtained with atomic absorption spectrometry. Sensitivity and detection limits were compared with other voltammetric methods, and the sw-BiNTs are deemed to be an attractive alternative for practical applications. Other features of the electrode include low costs, a well reproducible nanostructure, and ease of scale-up of the fabrication process. (author)

  14. Glucose aided synthesis of molybdenum sulfide/carbon nanotubes composites as counter electrode for high performance dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • The glucose aided (G-A) preparation of MoS2/CNTs composites were employed as CE in Pt-free DSSC. • The (G-A) MoS2/CNTs* CE showed the low Rct of 1.77 Ω cm2. • The efficiency of the DSSC reached 7.92% based on the (G-A) MoS2/CNTs* CE. - Abstract: In our present study, the composites of molybdenum disulfide/carbon nanotubes (MoS2/CNTs) were synthesized with glucose aided (G-A) by using an in situ hydrothermal route, and proposed as counter electrode (CE) catalyst in the dye-sensitized solar cells (DSSCs) for enhancing electrocatalytic activity toward the reduction of triiodide. The MoS2/CNTs composites with tentacle-like structure were confirmed by using the scanning and transmission electron microscopy. The superior structural characteristics including large active surface area and particularly the unique tentacle-like nanostructure along with 3D large interconnected interstitial volume guaranteed fast mass transport for the electrolyte, and enabled the (G-A) MoS2/CNTs CE to speed up the reduction of triiodide to iodide. The extensive electrochemical studies by the cyclic voltammetry, electrochemical impedence spectroscopy and Tafel measurements indicated that the (G-A) MoS2/CNTs CE possessed superior electrocatalytic activity, great electrochemical stability and impressive low charge transfer resistance on the electrolyte|electrode interface (1.77 Ω cm2) in the triiodide/iodide system compared to the pristine MoS2, MoS2/C and sputtered Pt CEs. The DSSC assembled with the novel (G-A) MoS2/CNTs CE exhibited high power conversion efficiency of 7.92% under the illumination of 100 mW cm−2, comparable to that of the DSSC with the Pt electrode (7.11%)

  15. Electrocatalytic detection of dopamine in the presence of ascorbic acid and uric acid using single-walled carbon nanotubes modified electrode.

    Science.gov (United States)

    Li, Yaya; Du, Jie; Yang, Jiandong; Liu, Dong; Lu, Xiaoquan

    2012-09-01

    Single-walled carbon nanotubes (SWCNTs) fabricated by sodium dodecyl sulfate (SDS) (f-SWCNTs) modified glassy carbon electrodes (f-SWCNTs/GCE) for the simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA). The f-SWCNTs/GCE displayed very good electrochemical catalytic activities with respect to GCE. The oxidation over-potentials of DA and UA decreased dramatically, and their oxidation peak currents increased significantly at f-SWCNTs/GCE compared to those obtained at the bare GCE. Simultaneously, the oxidation peak currents of AA decreased accordingly. The f-SWCNTs/GCE not only divide the overlapping voltammetric responses of them into individual voltammetric peaks, but also totally eliminate the interference from AA and distinguish DA from UA. The catalytic peak currents obtained from square-wave voltammetry increased linearly with increasing DA concentrations in the range of 5.0×10(-6) to 1.0×10(-4)M with a detection limit of 2.0×10(-8)M (S/N=3). The method was also successfully applied for determination of DA and showed good recovery in some biological fluids. PMID:22580482

  16. Preparation of yttrium hexacyanoferrate/carbon nanotube/Nafion nanocomposite film-modified electrode: Application to the electrocatalytic oxidation of L-cysteine

    Energy Technology Data Exchange (ETDEWEB)

    Qu Lingbo, E-mail: qulingbo@zzu.edu.c [Department of Chemistry, Zhengzhou University, Kexue Road, Zhengzhou 450001 (China); Chemistry and Chemical Engineering School, Henan University of Technology, Zhengzhou 450001 (China); College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang 455002 (China); Yang Suling [Department of Chemistry, Zhengzhou University, Kexue Road, Zhengzhou 450001 (China); Li Gang [College of Chemistry and Chemical Engineering, Anyang Normal University, Anyang 455002 (China); Yang Ran; Li Jianjun; Yu Lanlan [Department of Chemistry, Zhengzhou University, Kexue Road, Zhengzhou 450001 (China)

    2011-02-28

    An yttrium hexacyanoferrate nanoparticle/multi-walled carbon nanotube/Nafion (YHCFNP/MWNT/Nafion)-modified glassy carbon electrode (GCE) was constructed. Several techniques, including infrared spectroscopy, energy dispersive spectrometry, scanning electron microscopy and electrochemistry, were performed to characterize the yttrium hexacyanoferrate nanoparticles. The electrochemical behavior of the YHCFNP/MWNT/Nafion-modified GCE in response to L-cysteine oxidation was studied. The response current of L-cysteine oxidation at the YHCFNP/MWNT/Nafion-modified GCE was obviously higher than that at the bare GCE or other modified GCE. The effects of pH, scan rate and interference on the response to L-cysteine oxidation were investigated. In addition, on the basis of these findings, a determination of L-cysteine at the YHCFNP/MWNT/Nafion-modified GCE was carried out. Under the optimum experimental conditions, the electrochemical response to L-cysteine at the YHCFNP/MWNT/Nafion-modified GCE was fast (within 4 s). Linear calibration plots were obtained over the range of 0.20-11.4 {mu}mol L{sup -1} with a low detection limit of 0.16 {mu}mol L{sup -1}. The YHCFNP/MWNT/Nafion-modified GCE exhibited several advantages, such as high stability and good resistance against interference by ascorbic acid and other oxidizable amino acids.

  17. A CNT (carbon nanotube) paper as cathode gas diffusion electrode for water management of passive μ-DMFC (micro-direct methanol fuel cell) with highly concentrated methanol

    International Nuclear Information System (INIS)

    A novel MEA (membrane electrode assembly) structure of passive μ-DMFC (micro-direct methanol fuel cell) controls water management and decreases methanol crossover. The CNT (carbon nanotube) paper replacing CP (carbon paper) as GDL (gas diffusion paper) enhances water back diffusion which passively prevents flooding in the cathode and promotes low methanol crossover. Moreover, the unique structure of CNT paper can also enhance efficiency of oxygen mass transport and catalyst utilization. The passive μ-DMFC with CNT-MEA exhibits significantly higher performance than passive μ-DMFC with CP-MEA and can operate in high methanol concentration, showing the peak power density of 23.2 mW cm−2. The energy efficiency and fuel utilization efficiency are obviously improved from 11.54% to 22.7% and 36.61%–49.34%, respectively, and the water transport coefficient is 0.47 which is lower than previously reported passive μ-DMFC with CP. - Highlights: • This novel GDL (gas diffusion layer) solves water management and methanol crossover. • This GDL creates a hydraulic pressure in the cathode increasing water back diffusion. • This GDL improves the electrical conductivity and activity of catalyst

  18. Amperometric Detection of Aqueous Silver Ions by Inhibition of Glucose Oxidase Immobilized on Nitrogen-Doped Carbon Nanotube Electrodes.

    Science.gov (United States)

    Rust, Ian M; Goran, Jacob M; Stevenson, Keith J

    2015-07-21

    An amperometric glucose biosensor based on immobilization of glucose oxidase on nitrogen-doped carbon nanotubes (N-CNTs) was successfully developed for the determination of silver ions. Upon exposure to glucose, a steady-state enzymatic turnover rate was detected through amperometric oxidation of the H2O2 byproduct, directly related to the concentration of glucose in solution. Inhibition of the steady-state enzymatic glucose oxidase reaction by heavy metals ions such as Ag(+), produced a quantitative decrease in the steady-state rate, subsequently creating an ultrasensitive metal ion biosensor through enzymatic inhibition. The Ag(+) biosensor displayed a sensitivity of 2.00 × 10(8) ± 0.06 M(-1), a limit of detection (σ = 3) of 0.19 ± 0.04 ppb, a linear range of 20-200 nM, and sample recovery at 101 ± 2%, all acquired at a low-operating potential of 0.05 V (vs Hg/Hg2SO4). Interestingly, the biosensor does not display a loss in sensitivity with continued use due to the % inhibition based detection scheme: loss of enzyme (from continued use) does not influence the % inhibition, only the overall current associated with the activity loss. The heavy metals Cu(2+) and Co(2+) were also detected using the enzyme biosensor but found to be much less inhibitory, with sensitivities of 1.45 × 10(6) ± 0.05 M(-1) and 2.69 × 10(3) ± 0.07 M(-1), respectively. The mode of GOx inhibition was examined for both Ag(+) and Cu(2+) using Dixon and Cornish-Bowden plots, where a strong correlation was observed between the inhibition constants and the biosensor sensitivity. PMID:26079664

  19. Silver-functionalized carbon nanofiber composite electrodes for ibuprofen detection

    OpenAIRE

    Manea, F.; Motoc, S.; Pop, A.(National Institute for Physics and Nuclear Engineering, Bucharest, Romania); Remes, A.; Schoonman, J.

    2012-01-01

    The aim of this study is to prepare and characterize two types of silver-functionalized carbon nanofiber (CNF) composite electrodes, i.e., silver-decorated CNF-epoxy and silver-modified natural zeolite-CNF-epoxy composite electrodes suitable for ibuprofen detection in aqueous solution. Ag carbon nanotube composite electrode exhibited the best electroanalytical parameters through applying preconcentration/differential-pulsed voltammetry scheme.

  20. Aligned Carbon Nanotubes Array by DC Glow Plasma Etching for Supercapacitor

    OpenAIRE

    Yongfeng Luo; Xi Li; Zhiqiang Gong; Zhongzhi Sheng; Xiaofang Peng; Qunying Mou; Mengdong He; Xianjun Li; Hong Chen

    2013-01-01

    To open the end of carbon nanotubes and make these ends connect with functional carboxyl group, aligned carbon nanotubes (CNTs) arrays was etched by DC glow oxygen-argon plasma. With these open-ended carbon nanotubes array as electrode materials to build supercapacitor, we found that the capacity (32.2 F/g) increased significantly than that of pure carbon nanotubes (6.7 F/g).

  1. Shot noise in carbon nanotube based Fabry-Perot interferometers

    OpenAIRE

    Herrmann, L.G.; Delattre, T.; Morfin, P.; Berroir, J. -M.; Plaçais, B.; Glattli, D.C.; Kontos, T.

    2007-01-01

    We report on shot noise measurements in carbon nanotube based Fabry-Perot electronic interferometers. As a consequence of quantum interferences, the noise power spectral density oscillates as a function of the voltage applied to the gate electrode. The quantum shot noise theory accounts for the data quantitatively. It allows to confirm the existence of two nearly degenerate orbitals. At resonance, the transmission of the nanotube approaches unity, and the nanotube becomes noiseless, as observ...

  2. Polymer cantilever platform for dielectrophoretic assembly of carbon nanotubes

    DEFF Research Database (Denmark)

    Johansson, Alicia; Calleja, M.; Dimaki, Maria;

    2004-01-01

    A polymer cantilever platform for dielectrophoretic assembly of carbon nanotubes has been designed and realized. Multi-walled carbon nanotubes from aqueous solution have been assembled between two metal electrodes that are separated by 2 mu m and embedded in the polymer cantilever. The entire chip......, except for the metallic electrodes and wiring, was fabricated in the photoresist SU-8. SU-8 allows for an inexpensive, flexible and fast fabrication method, and the cantilever platform provides a hydrophobic surface that should be well suited for nanotube assembly. The device can be integrated in a micro...

  3. Determination of the intershell conductance in a multiwall carbon nanotube

    Science.gov (United States)

    Stetter, A.; Vancea, J.; Back, C. H.

    2008-10-01

    We have measured the current induced voltage drop along an individual multiwall carbon nanotube as a function of the distance to the current injecting electrode. The measurements have been performed at room temperature using scanning probe potentiometry combined with scanning electron microscopy. For a nanotube with an incomplete outer shell, a sharp potential jump was observed at the end of the outermost shell. The electric potential variation along the carbon nanotube has been used to determine the contact resistance between metal electrodes and the tube, the intrashell resistance, and the intershell conductance.

  4. Contacting single bundles of carbon nanotubes with alternating electric fields

    OpenAIRE

    Krupke, R.; Hennrich, F.; Weber, H. B.; Beckmann, D.; Hampe, O.; Malik, S.; Kappes, M. M.; Löhneysen, H. v.

    2002-01-01

    Single bundles of carbon nanotubes have been selectively deposited from suspensions onto sub-micron electrodes with alternating electric fields. We explore the resulting contacts using several solvents and delineate the differences between Au and Ag as electrode materials. Alignment of the bundles between electrodes occurs at frequencies above 1 kHz. Control over the number of trapped bundles is achieved by choosing an electrode material which interacts strongly with the chemical functional g...

  5. Studies of Carbon Nanotubes

    Science.gov (United States)

    Caneba, Gerard T.

    2005-01-01

    The fellowship experience for this summer for 2004 pertains to carbon nanotube coatings for various space-related applications. They involve the following projects: (a) EMI protection films from HiPco-polymers, and (b) Thermal protection nanosilica materials. EMI protection films are targeted to be eventually applied onto casings of laptop computers. These coatings are composites of electrically-conductive SWNTs and compatible polymers. The substrate polymer will be polycarbonate, since computer housings are typically made of carbon composites of this type of polymer. A new experimental copolymer was used last year to generate electrically-conductive and thermal films with HiPco at 50/50 wt/wt composition. This will be one of the possible formulations. Reference films will be base polycarbonate and neat HiPco onto polycarbonate films. Other coating materials that will be tried will be based on HiPco composites with commercial enamels (polyurethane, acrylic, polyester), which could be compatible with the polycarbonate substrate. Nanosilica fibers are planned for possible use as thermal protection tiles on the shuttle orbiter. Right now, microscale silica is used. Going to the nanoscale will increase the surface-volume-per-unit-area of radiative heat dissipation. Nanoscale carbon fibers/nanotubes can be used as templates for the generation of nanosilica. A sol-gel operation is employed for this purpose.

  6. Teslaphoresis of Carbon Nanotubes.

    Science.gov (United States)

    Bornhoeft, Lindsey R; Castillo, Aida C; Smalley, Preston R; Kittrell, Carter; James, Dustin K; Brinson, Bruce E; Rybolt, Thomas R; Johnson, Bruce R; Cherukuri, Tonya K; Cherukuri, Paul

    2016-04-26

    This paper introduces Teslaphoresis, the directed motion and self-assembly of matter by a Tesla coil, and studies this electrokinetic phenomenon using single-walled carbon nanotubes (CNTs). Conventional directed self-assembly of matter using electric fields has been restricted to small scale structures, but with Teslaphoresis, we exceed this limitation by using the Tesla coil's antenna to create a gradient high-voltage force field that projects into free space. CNTs placed within the Teslaphoretic (TEP) field polarize and self-assemble into wires that span from the nanoscale to the macroscale, the longest thus far being 15 cm. We show that the TEP field not only directs the self-assembly of long nanotube wires at remote distances (>30 cm) but can also wirelessly power nanotube-based LED circuits. Furthermore, individualized CNTs self-organize to form long parallel arrays with high fidelity alignment to the TEP field. Thus, Teslaphoresis is effective for directed self-assembly from the bottom-up to the macroscale. PMID:27074626

  7. Carbon Nanotube Amperometric Chips with Pneumatic Micropumps

    Science.gov (United States)

    Tsujita, Yuichi; Maehashi, Kenzo; Matsumoto, Kazuhiko; Chikae, Miyuki; Torai, Soichiro; Takamura, Yuzuru; Tamiya, Eiichi

    2008-04-01

    We fabricated carbon nanotube (CNT) amperometric chips with pneumatic micropumps by the combination of amperometric biosensors based on CNT-arrayed electrodes and microchannels with pneumatic micropumps made of poly(dimethylsiloxane). On the chip, phosphate buffer solution and potassium ferricyanide, K3[Fe(CN)6], were introduced into the CNT electrodes using each pneumatic micropump and electrochemically measured by differential pulse voltammetry. The results indicate that our chip can automatically exchange reagents on the CNT electrodes and clearly detect molecules. Moreover, by modifying the CNT electrodes with enzyme glucose oxidase, glucose molecules could be detected using our chips by cyclic voltammetry and chronoamperometry. We conclude that microfluidic chips with CNT-arrayed electrodes are a promising candidate for the development of hand-held electrochemical biosensors.

  8. Nanocomposite of hexagonal β-Ni(OH){sub 2}/multiwalled carbon nanotubes as high performance electrode for hybrid supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Chaitra, K. [Department of Nanobiosciences, Centre for Emerging Technologies, Jain Global Campus, Jain University, Jakkasandra Post, Kanakapura Taluk, Ramanagara District, Bangalore Rural 562112, Karnataka (India); Nagaraju, N. [Department of Chemistry, St. Joseph' s College P.G. Centre, 46, Langford Road, Shanthinagar, Bangalore 560027, Karnataka (India); Nagaraju, Kathyayini, E-mail: nkathyayini45@gmail.com [Department of Nanobiosciences, Centre for Emerging Technologies, Jain Global Campus, Jain University, Jakkasandra Post, Kanakapura Taluk, Ramanagara District, Bangalore Rural 562112, Karnataka (India)

    2015-08-15

    β-Ni(OH){sub 2} and its composite with multiwalled carbon nanotubes (MWCNTs) were synthesized by hydrothermal process. Their electrochemical properties such as specific capacitance, energy density, power density, coulombic efficiency and charge-discharge cycles were investigated by Cyclic voltammetry (CV), Chronopotentiometry (CP) and Electrochemical impedance spectroscopy (EIS) techniques. The materials were analyzed for their textural and structural properties by different analytical techniques such as Powder X-ray diffraction (PXRD), Brunauer-Emmett-Teller (BET) surface area, Scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDS), Transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), and Raman spectroscopy. The diffraction peaks obtained from PXRD studies and the TEM images of the materials inferred the formation of hexagonal nanostructured β- Ni(OH){sub 2} in both pure and composite materials. The composite material exhibited better electrochemical supercapacitance performance than pure β-Ni(OH){sub 2}. Their specific capacitance values were found to be 1882 F g{sup −1} and 819 F g{sup −1} respectively at a scan rate of 2 mVs{sup −1}. The presence of MWCNTs enhanced the specific capacitance value of β-Ni(OH){sub 2} nearly by 57% at 2 mVs{sup −1}. Chronopotentiometric studies conducted at a current density of 5 A/g indicated that the composite material was stable up to 5000 charge-discharge cycles. Another interesting observation made is that the composite material exhibited 100% coulombic efficiency where as it was only 84% for β-Ni(OH){sub 2} at 5000th cycle. The composite material gave an energy density of 40 Wh/kg which was nearly 4 times that of β-Ni(OH){sub 2}. - Graphical abstract: Display Omitted - Highlights: • β-Ni(OH){sub 2} and its composite with MWCNTs were synthesized by hydrothermal process. • β-Ni(OH){sub 2} and composite exhibited Csp of 819 and 1882 F/g at 2 m

  9. Luminescence of carbon nanotube bulbs

    Institute of Scientific and Technical Information of China (English)

    LI ChuanGang; WU DeHai; WANG KunLin; WEI JinQuan; WEI BingQing; ZHU HongWei; WANG ZhiCheng; LUO JianBin; LIU WenJin; ZHENG MingXin

    2007-01-01

    Carbon nanotube (CNT) bulbs made of decimeter-scale double-walled carbon nanotube (DWCNT) strands and films were fabricated and their luminescence properties, including the lighting efficiency, voltage-current relation and thermal stability were investigated. The results show that the DWCNT bulb has a comparable spectrum of visible light with tungsten bulb and its average efficiency is 40% higher than that of a tungsten filament at the same temperature (1400-2300 K). The nanotube filaments show both resistance and thermal stability over a large temperature region. No obvious damage was found for a nanotube bulb illuminating at 2300 K for more than 24 hours in vacuum.

  10. Effect of polarization of ultrafast laser irradiation on carbon nanotube film

    International Nuclear Information System (INIS)

    Selective patterning of carbon nanotubes film on transparent substrates was performed using a femtosecond laser. The high shock wave generated by the femtosecond laser effectively removed the carbon nanotubes without damage to the substrate. This process has many advantages because it is performed without chemicals and is easily applied to large-area patterning. It could also control the transparency and conductivity of carbon nanotubes film by selective removal of carbon nanotubes. Furthermore, a femtosecond laser does not cause any phase change in the CNTs, as usually occurs in focused ion beam irradiation of carbon nanotubes. The patterned single-walled carbon nanotube films on transparent substrate can be used as an electrode layer for touch panels of flexible or flat panel displays instead of indium tin oxide film. - Highlights: • Fabrication of topological architectures on carbon nanotube-based coatings. • Patterning of single-walled carbon nanotubes film to femtosecond laser pulses. • Femtosecond laser-induced nanotubes alignment

  11. PEDOT:PSS and glucose assisted preparation of molybdenum disulfide/single-wall carbon nanotubes counter electrode and served in dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Graphical abstract: Much higher photovoltaic performance of dye-sensitized solar cell with (G-P-A) MoS2/SWCNTs counter electrode than that of Pt configuration device. - Highlights: • The (G-P-A) MoS2/SWCNTs composite were first time prepared and employed as counter electrode (CE) in Pt-free DSSC;. • The (G-P-A) MoS2/SWCNTs CE showed the low Rct of 1.46 Ω·cm2;. • The photo-electric conversion efficiency of the DSSC reached 8.14% based on the (G-P-A) MoS2/SWCNTs CE. - Abstract: A flower-like structure complexes of molybdenum disulfide/single-wall carbon nanotubes (MoS2/SWCNTs) are for the first time synthesized with glucose and poly (3, 4-ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT:PSS) assisted (G-P-A) by the use of an in situ hydrothermal route, and proposed as counter electrode (CE) catalyst for Pt-free dye-sensitized solar cells (DSSCs). The DSSC assembled with the (G-P-A) MoS2/SWCNTs CE exhibits a high photo-electric conversion efficiency of 8.14% under the illumination of 100 mW·cm−2, comparable to that of the DSSC Pt-based (7.78%). Furthermore, the surface morphology of the (G-P-A) MoS2/SWCNTs complexes with flower-like structure is confirmed by using the scanning and transmission electron microscopes (SEM). The superior structural characteristic along with 3D large interconnected interstitial volume is advantageous fast mass transport for the electrolyte, and enables the (G-P-A) MoS2/SWCNTs CE to speed up the reduction of triiodide to iodide. The electrochemical performance of the sample is analyzed from cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It indicates that the (G-P-A) MoS2/SWCNTs CE possesses excellent electrocatalytic activity in iodide/triiodide electrolyte and lower charge transfer resistance of 1.46 Ω·cm2 compared to the Pt electrode (2.44 Ω·cm2). Sum up, the (G-P-A) MoS2/SWCNTs CE can be considered as a promising alternative CE for Pt-free DSSCs

  12. Unexpected Li2O2 Film Growth on Carbon Nanotube Electrodes with CeO2 Nanoparticles in Li-O2 Batteries.

    Science.gov (United States)

    Yang, Chunzhen; Wong, Raymond A; Hong, Misun; Yamanaka, Keisuke; Ohta, Toshiaki; Byon, Hye Ryung

    2016-05-11

    In lithium-oxygen (Li-O2) batteries, it is believed that lithium peroxide (Li2O2) electrochemically forms thin films with thicknesses less than 10 nm resulting in capacity restrictions due to limitations in charge transport. Here we show unexpected Li2O2 film growth with thicknesses of ∼60 nm on a three-dimensional carbon nanotube (CNT) electrode incorporated with cerium dioxide (ceria) nanoparticles (CeO2 NPs). The CeO2 NPs favor Li2O2 surface nucleation owing to their strong binding toward reactive oxygen species (e.g., O2 and LiO2). The subsequent film growth results in thicknesses of ∼40 nm (at cutoff potential of 2.2 V vs Li/Li(+)), which further increases up to ∼60 nm with the addition of trace amounts of H2O that enhances the solution free energy. This suggests the involvement of solvated superoxide species (LiO2(sol)) that precipitates on the existing Li2O2 films to form thicker films via disproportionation. By comparing toroidal Li2O2 formed solely from LiO2(sol), the thick Li2O2 films formed from surface-mediated nucleation/thin-film growth following by LiO2(sol) deposition provides the benefits of higher reversibility and rapid surface decomposition during recharge. PMID:27105122

  13. A Novel Asymmetric Supercapacitor Designed with Mn3O4@Multi-wall Carbon Nanotube Nanocomposite and Reduced Graphene Oxide Electrodes

    Science.gov (United States)

    Mandal, Manas; Ghosh, Debasis; Chattopadhyay, Krishna; Das, Chapal Kumar

    2016-07-01

    We demonstrate a straightforward process for the synthesis and fabrication of a hybrid-type asymmetric supercapacitor (ASC) by combining Mn3O4 nanoparticle-supported multi-wall carbon nanotube (Mn3O4@MWCNT) composite as positive and reduced graphene oxide (rGO) as negative electrodes. A controlled hydrothermal synthesis of Mn3O4 in the presence of MWCNT resulted in a well-distributed Mn3O4 nanoparticles on the MWCNT backbone in the Mn3O4@MWCNT composite. The structure and morphology of the as-prepared materials have been investigated by x-ray diffraction, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller analysis and x-ray photoelectron spectroscopy measurements. The electrochemical characterizations were carried out in terms of cyclic voltammetry, galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy analysis. The constructed ASC with 1 M KOH-supporting electrolyte was able to provide high-specificity capacitance of 173.36 F/g at 2 mV/s scan rate and high-energy density of 26.8 Wh/kg accompanied by high cycle stability with 79.3% capacitance retention over 3000 GCD cycles.

  14. Flexible carbon nanotube/polypropylene composite plate decorated with poly(3,4-ethylenedioxythiophene) as efficient counter electrodes for dye-sensitized solar cells

    Science.gov (United States)

    Lin, Jeng-Yu; Wang, Wei-Yen; Chou, Shu-Wei

    2015-05-01

    In this study, we fabricate an efficient, flexible and low-cost counter electrode (CE) composed of a plasma-etched carbon nanotubes/polypropylene (designated as ECP) composite plate decorated with poly(3,4-ethylene dioxythiophene) (PEDOT) for dye-sensitized solar cells (DSCs). The PEDOT-decorated monolithic ECP CEs are fabricated via series of processes including high-temperature refluxing, thermal compression, oxygen plasma etching, and electropolymerization. The bottom ECP plate is used to replace conventional transparent conducting oxide (TCO) as a conductive substrate, and the top PEDOT layer is employed as catalyst for I3- reduction. According to the extensive electrochemical measurements, the as-fabricated flexible PEDOT coated ECP CE demonstrates a Pt-like electrocatalytic for I3- reduction. The DSC based on the flexible PEDOT-decorated ECP CE yields impressive energy conversion efficiency of 6.82% (or 6.77% even after the bending test), which is comparable to that of the DSC using the Pt CE (7.20%) under similar device architecture conditions. Therefore, the PEDOT-decorated ECP based CEs show the possibility of serving as low-cost and flexible CEs for efficient DSCs.

  15. Electrochemical sensor using neomycin-imprinted film as recognition element based on chitosan-silver nanoparticles/graphene-multiwalled carbon nanotubes composites modified electrode.

    Science.gov (United States)

    Lian, Wenjing; Liu, Su; Yu, Jinghua; Li, Jie; Cui, Min; Xu, Wei; Huang, Jiadong

    2013-06-15

    A novel imprinted electrochemical sensor for neomycin recognition was developed based on chitosan-silver nanoparticles (CS-SNP)/graphene-multiwalled carbon nanotubes (GR-MWCNTs) composites decorated gold electrode. Molecularly imprinted polymers (MIPs) were synthesized by electropolymerization using neomycin as the template, and pyrrole as the monomer. The mechanism of the fabrication process and a number of factors affecting the activity of the imprinted sensor have been discussed and optimized. The characterization of imprinted sensor has been carried out by scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). The performance of the proposed imprinted sensor has been investigated using cyclic voltammetry (CV) and amperometry. Under the optimized conditions, the linear range of the sensor was from 9×10(-9)mol/L to 7×10(-6)mol/L, with the limit of detection (LOD) of 7.63×10(-9)mol/L (S/N=3). The film exhibited high binding affinity and selectivity towards the template neomycin, as well as good reproducibility and stability. Furthermore, the proposed sensor was applied to determine the neomycin in milk and honey samples based on its good reproducibility and stability, and the acceptable recovery implied its feasibility for practical application. PMID:23395725

  16. Preparation of Carbon Nanotube/TiO2 Mesoporous Hybrid Photoanode with Iron Pyrite (FeS2) Thin Films Counter Electrodes for Dye-Sensitized Solar Cell

    Science.gov (United States)

    Kilic, Bayram; Turkdogan, Sunay; Astam, Aykut; Ozer, Oguz Can; Asgin, Mansur; Cebeci, Hulya; Urk, Deniz; Mucur, Selin Pravadili

    2016-05-01

    Multi-walled carbon nanotube (MWCNT)/TiO2 mesoporous networks can be employed as a new alternative photoanode in dye-sensitized solar cells (DSSCs). By using the MWCNT/TiO2 mesoporous as photoanodes in DSSC, we demonstrate that the MWCNT/TiO2 mesoporous photoanode is promising alternative to standard FTO/TiO2 mesoporous based DSSC due to larger specific surface area and high electrochemical activity. We also show that iron pyrite (FeS2) thin films can be used as an efficient counter electrode (CE), an alternative to the conventional high cost Pt based CE. We are able to synthesis FeS2 nanostructures utilizing a very cheap and easy hydrothermal growth route. MWCNT/TiO2 mesoporous based DSSCs with FeS2 CE achieved a high solar conversion efficiency of 7.27% under 100 mW cm‑2 (AM 1.5G 1-Sun) simulated solar irradiance which is considerably (slightly) higher than that of A-CNT/TiO2 mesoporous based DSSCs with Pt CE. Outstanding performance of the FeS2 CE makes it a very promising choice among the various CE materials used in the conventional DSSC and it is expected to be used more often to achieve higher photon-to-electron conversion efficiencies.

  17. Flowerlike molybdenum sulfide/multi-walled carbon nanotube hybrid as Pt-free counter electrode used in dye-sensitized solar cells

    International Nuclear Information System (INIS)

    A flowerlike molybdenum sulfide/multi-walled carbon nanotube (MoS2/MWCNT) hybrid is prepared and used as an efficient Pt-free counter electrode (CE) for dye-sensitized solar cells (DSSCs). Field emission scanning electron microscopy observes that the flowerlike MoS2/MWCNTs possess lamellar and large specific surface area, which benefits the enhancement of electrocatalytic activity. Cyclic voltammogram measurement indicates that MoS2/MWCNT CE has larger current density smaller overpotential than MoS2, MWCNT, even Pt CEs. Electrochemical impedance spectroscopy shows that the MoS2/MWCNT with optimal MWCNT content has low charge-transfer resistance of 2.05 Ω × cm2 and series resistance of 1.13 Ω·cm2. Under simulated solar light irradiation with intensity of 100 mW·cm−2 (AM 1.5), the DSSC based on the MoS2/MWCNT CE achieves a power conversion efficiency of 7.50 %, which is comparable with the solar cells based on the Pt CE (7.49%)

  18. Electrochemical lactate biosensor based upon chitosan/carbon nanotubes modified screen-printed graphite electrodes for the determination of lactate in embryonic cell cultures.

    Science.gov (United States)

    Hernández-Ibáñez, Naiara; García-Cruz, Leticia; Montiel, Vicente; Foster, Christopher W; Banks, Craig E; Iniesta, Jesús

    2016-03-15

    l-lactate is an essential metabolite present in embryonic cell culture. Changes of this important metabolite during the growth of human embryo reflect the quality and viability of the embryo. In this study, we report a sensitive, stable, and easily manufactured electrochemical biosensor for the detection of lactate within embryonic cell cultures media. Screen-printed disposable electrodes are used as electrochemical sensing platforms for the miniaturization of the lactate biosensor. Chitosan/multi walled carbon nanotubes composite have been employed for the enzymatic immobilization of the lactate oxidase enzyme. This novel electrochemical lactate biosensor analytical efficacy is explored towards the sensing of lactate in model (buffer) solutions and is found to exhibit a linear response towards lactate over the concentration range of 30.4 and 243.9 µM in phosphate buffer solution, with a corresponding limit of detection (based on 3-sigma) of 22.6 µM and exhibits a sensitivity of 3417 ± 131 µAM(-1) according to the reproducibility study. These novel electrochemical lactate biosensors exhibit a high reproducibility, with a relative standard deviation of less than 3.8% and an enzymatic response over 82% after 5 months stored at 4 °C. Furthermore, high performance liquid chromatography technique has been utilized to independently validate the electrochemical lactate biosensor for the determination of lactate in a commercial embryonic cell culture medium providing excellent agreement between the two analytical protocols. PMID:26579934

  19. One-step synthesis of layered CuS/multi-walled carbon nanotube nanocomposites for supercapacitor electrode material with ultrahigh specific capacitance

    International Nuclear Information System (INIS)

    In this work, hierarchical-structured copper sulfide/multi-walled carbon nanotubes (CuS/MWCNTs) are synthesized via a one-step hydrothermal process. The chemical composition and microstructure of CuS-MWCNTs are characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy and research as electrode matericals for high-performance supercapacitors by cyclic voltammogram, galvanostatic charge-discharge and electrochemical impedance spectroscopy. As expected, the CuS-MWCNTs exhibit a much higher specific capacitance up to 2831 F g−1, compared with 925.1 F g−1 for CuS and 555.6 F g−1 for MWCNTs. Furthermore, the CuS-MWCNTs hybrids also exhibit good cycling stability with more than 90% capacitance retention over 600 cycles. The enhancement of CuS/MWCNTs in supercapacitor performance not only attribute to their unique 3D structures with large specific surface area, but also their excellent conductivity, which facilitate efficient charge transport and promotes electrolyte diffusion

  20. Immobilization of the laccases from trametes versicolor and streptomyces coelicolor on single-wall carbon nanotube electrodes: a molecular dynamics study

    Energy Technology Data Exchange (ETDEWEB)

    Trohalaki, S. [Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, OH (United States); General Dynamics Information Technology, Dayton, OH (United States); Pachter, R. [Materials and Manufacturing Directorate, Air Force Research Laboratory, Wright-Patterson Air Force Base, OH (United States); Luckarift, H.R. [Materials and Manufacturing Directorate, Air Force Research Laboratory, Tyndall Air Force Base, FL (United States); Universal Technology Corporation, Dayton, OH (United States); Johnson, G.R. [Materials and Manufacturing Directorate, Air Force Research Laboratory, Tyndall Air Force Base, FL (United States)

    2012-08-15

    In this work, we investigate the immobilization of laccases from Trametes versicolor (TvL) and the small laccase (SLAC) from Streptomyces coelicolor on single-wall carbon nanotube (SWCNT) surfaces. SLAC may potentially offer improved adsorption on the electrode, thus improving bioelectrocatalytic activity via direct electron transfer (DET). Laccase immobilization on SWCNTs is achieved non-covalently with a molecular tether (1-pyrene butanoic acid, succinimidyl ester) that forms an amide bond with an amine group on the laccase surface while the pyrene coordinates to the SWCNT by {pi}-{pi} stacking. In our approach, density functional theory calculations were first used to model the interaction energies between SWCNTs and pyrene to validate an empirical force field, thereafter applied in molecular dynamics (MD) simulations. In the simulated models, the SWCNT was placed near the region of the (type 1) Cu(T1) atom in the laccases, and in proximity to other regions where adsorption seems likely. Calculated interaction energies between the SWCNTs and laccases and distances between the SWCNT surface and the Cu(T1) atom have shown that SWCNTs adsorb more strongly to SLAC than to TvL, and that the separation between the SWCNTs and Cu(T1) atoms is smaller for SLAC than for TvL, having implications for improved DET. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. A Novel Asymmetric Supercapacitor Designed with Mn3O4@Multi-wall Carbon Nanotube Nanocomposite and Reduced Graphene Oxide Electrodes

    Science.gov (United States)

    Mandal, Manas; Ghosh, Debasis; Chattopadhyay, Krishna; Das, Chapal Kumar

    2016-04-01

    We demonstrate a straightforward process for the synthesis and fabrication of a hybrid-type asymmetric supercapacitor (ASC) by combining Mn3O4 nanoparticle-supported multi-wall carbon nanotube (Mn3O4@MWCNT) composite as positive and reduced graphene oxide (rGO) as negative electrodes. A controlled hydrothermal synthesis of Mn3O4 in the presence of MWCNT resulted in a well-distributed Mn3O4 nanoparticles on the MWCNT backbone in the Mn3O4@MWCNT composite. The structure and morphology of the as-prepared materials have been investigated by x-ray diffraction, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, transmission electron microscopy, Brunauer-Emmett-Teller analysis and x-ray photoelectron spectroscopy measurements. The electrochemical characterizations were carried out in terms of cyclic voltammetry, galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy analysis. The constructed ASC with 1 M KOH-supporting electrolyte was able to provide high-specificity capacitance of 173.36 F/g at 2 mV/s scan rate and high-energy density of 26.8 Wh/kg accompanied by high cycle stability with 79.3% capacitance retention over 3000 GCD cycles.

  2. Preparation of Carbon Nanotube/TiO2 Mesoporous Hybrid Photoanode with Iron Pyrite (FeS2) Thin Films Counter Electrodes for Dye-Sensitized Solar Cell

    Science.gov (United States)

    Kilic, Bayram; Turkdogan, Sunay; Astam, Aykut; Ozer, Oguz Can; Asgin, Mansur; Cebeci, Hulya; Urk, Deniz; Mucur, Selin Pravadili

    2016-01-01

    Multi-walled carbon nanotube (MWCNT)/TiO2 mesoporous networks can be employed as a new alternative photoanode in dye-sensitized solar cells (DSSCs). By using the MWCNT/TiO2 mesoporous as photoanodes in DSSC, we demonstrate that the MWCNT/TiO2 mesoporous photoanode is promising alternative to standard FTO/TiO2 mesoporous based DSSC due to larger specific surface area and high electrochemical activity. We also show that iron pyrite (FeS2) thin films can be used as an efficient counter electrode (CE), an alternative to the conventional high cost Pt based CE. We are able to synthesis FeS2 nanostructures utilizing a very cheap and easy hydrothermal growth route. MWCNT/TiO2 mesoporous based DSSCs with FeS2 CE achieved a high solar conversion efficiency of 7.27% under 100 mW cm−2 (AM 1.5G 1-Sun) simulated solar irradiance which is considerably (slightly) higher than that of A-CNT/TiO2 mesoporous based DSSCs with Pt CE. Outstanding performance of the FeS2 CE makes it a very promising choice among the various CE materials used in the conventional DSSC and it is expected to be used more often to achieve higher photon-to-electron conversion efficiencies. PMID:27243374

  3. Preparation of isolated carbon nanotubes

    International Nuclear Information System (INIS)

    Full text: Carbon nanotubes are of great interest for a large range of applications from physical chemistry, solid state physics to molecular quantum optics. We propose the preparation of molecular beams of isolated carbon nanotubes for future matter wave experiments, as well as for applications in the material sciences and spectroscopy. Carbon nanotubes may be particularly interesting for quantum experiments because of their low ionization threshold, high mechanical stability and high polarizability. This is expected to facilitate the cooling, coherent manipulation and efficient detection of such molecular beams. For this purpose we are investigating different methods of solvation, isolation and shortening of carbon nanotubes from commercial bundles. Length and diameter distributions are recorded by SPM whereas the unbundling of the tubes is determined by absorption spectroscopy. Established methods from physical chemistry, such as laser desorption are currently being modified and studied as potential tools for generating beams of nanotubes in the mass range of around 50.000-100.000 amu. (author)

  4. Scaling Law in Carbon Nanotube Electromechanical Devices

    OpenAIRE

    Lefevre, R.; Goffman, M.F.; Derycke, V.; Miko, C.; Forro, L.; Bourgoin, J. P.; Hesto, P.

    2005-01-01

    We report a method for probing electromechanical properties of multiwalled carbon nanotubes(CNTs). This method is based on AFM measurements on a doubly clamped suspended CNT electrostatically deflected by a gate electrode. We measure the maximum deflection as a function of the applied gate voltage. Data from different CNTs scale into an universal curve within the experimental accuracy, in agreement with a continuum model prediction. This method and the general validity of the scaling law cons...

  5. Dielectrophoretic assembly of carbon nanotube devices

    DEFF Research Database (Denmark)

    Dimaki, Maria

    The purpose of this project has been to assemble single-walled carbon nanotubes on electrodes at the tip of a biocompatible cantilever and use these for chemical species sensing in air and liquid, for example in order to measure the local activity from ion channels in the cell membrane. The elect...... and semiconducting. Raman spectra taken from samples assembled at different frequencies directly contradicted theoretical predictions as well as previously published experimental results.......The purpose of this project has been to assemble single-walled carbon nanotubes on electrodes at the tip of a biocompatible cantilever and use these for chemical species sensing in air and liquid, for example in order to measure the local activity from ion channels in the cell membrane...... nanotubes dispersed in a number of different liquids. As a result of these test experiments a cantilever probe was designed specifically for the dielectrophoretic assembly of carbon nanotubes and a prototype was fabricated in the MIC (now Danchip) cleanroom. The prototype is not yet fully operational...

  6. Electrochemical studies of U(VI)/U(IV) redox reaction in 1M H{sub 2}SO{sub 4} at single-walled carbon nanotubes (SWCNTs) modified gold (Au) electrode

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Ruma; Aggarwal,S.K. [Bhabha Atomic Reseach Centre, Trombay, Mumbai (India). Fuel Chemistry Div.

    2013-08-01

    Electrochemistry of U(VI)/U(IV) couple in 1 M H{sub 2}SO{sub 4} was studied on bare and SWCNT modified gold (Au) electrodes by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The gold electrode modified with single-walled carbon nanotubes (SWCNTs-Au) was characterized by scanning electron microscopy (SEM). Electrocatalysis of U(VI)/U(IV) redox reaction was observed on SWCNT-Au. The lower charge transfer resistance at SWCNT-Au promoted the rate of electron transfer reaction of U(VI)/U(IV) couple. These results are interesting to develop electroanalytical methodologies for uranium determination using SWCNT modified electrodes. To the best of our knowledge, this is the first study on the electrocatalysis of uranium on SWCNT modified electrode. (orig.)

  7. Boron carbide nanolumps on carbon nanotubes

    Science.gov (United States)

    Lao, J. Y.; Li, W. Z.; Wen, J. G.; Ren, Z. F.

    2002-01-01

    Boron carbide nanolumps are formed on the surface of multiwall carbon nanotubes by a solid-state reaction between boron and carbon nanotubes. The reaction is localized so that the integrity of the structure of carbon nanotubes is maintained. Inner layers of multiwall carbon nanotubes are also bonded to boron carbide nanolumps. These multiwall carbon nanotubes with boron carbide nanolumps are expected to be the ideal reinforcing fillers for high-performance composites because of the favorable morphology.

  8. Carbon nanotube network thin-film transistors on flexible/stretchable substrates

    Science.gov (United States)

    Takei, Kuniharu; Takahashi, Toshitake; Javey, Ali

    2016-03-29

    This disclosure provides systems, methods, and apparatus for flexible thin-film transistors. In one aspect, a device includes a polymer substrate, a gate electrode disposed on the polymer substrate, a dielectric layer disposed on the gate electrode and on exposed portions of the polymer substrate, a carbon nanotube network disposed on the dielectric layer, and a source electrode and a drain electrode disposed on the carbon nanotube network.

  9. Increased Alignment in Carbon Nanotube Growth

    Science.gov (United States)

    Delzeit, Lance D. (Inventor)

    2007-01-01

    Method and system for fabricating an array of two or more carbon nanotube (CNT) structures on a coated substrate surface, the structures having substantially the same orientation with respect to a substrate surface. A single electrode, having an associated voltage source with a selected voltage, is connected to a substrate surface after the substrate is coated and before growth of the CNT structures, for a selected voltage application time interval. The CNT structures are then grown on a coated substrate surface with the desired orientation. Optionally, the electrode can be disconnected before the CNT structures are grown.

  10. Simultaneous determination of 2,4,6-trichlorophenol and pentachlorophenol based on poly(Rhodamine B)/graphene oxide/multiwalled carbon nanotubes composite film modified electrode

    Science.gov (United States)

    Zhu, Xiaolin; Zhang, Kexin; Lu, Nan; Yuan, Xing

    2016-01-01

    In the present study, a poly(Rhodamine B)/graphene oxide/multiwalled carbon nanotubes nanocomposite modified glass carbon electrode (PRhB/GO/MWCNTs/GCE) was developed for the simultaneous determination of 2,4,6-trichlorophenol (2,4,6-TCP) and pentachlorophenol (PCP). The PRhB/GO/MWCNTs film was extensively characterized by emission scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy and electrochemical impedance spectroscopy (EIS). The electrochemical behaviors of 2,4,6-TCP and PCP were investigated by cyclic voltammetry, linear sweep voltammetry and differential pulse voltammetry. Due to the synergistic effect, the PRhB/GO/MWCNTs/GCE significantly facilitated the simultaneous electro-oxidation of 2,4,6-TCP and PCP with peak potential difference of 160 mV and enhanced oxidation currents. Under optimum conditions, the oxidation current of 2,4,6-TCP was linear to its concentration in the ranges of 4.0 × 10-9 to 1.0 × 10-7 M and 1.0 × 10-7 to 1.0 × 10-4 M with the detection limit (S/N = 3) of 8.0 × 10-10 M. And the linear concentration ranges for PCP were 2.0 × 10-9 to 1.0 × 10-7 M and 1.0 × 10-7 to 9.0 × 10-5 M with the detection limit of 5.0 × 10-10 M. Moreover, the proposed PRhB/GO/MWCNTs/GCE was successfully applied to the simultaneous determination of 2,4,6-TCP and PCP in practical water samples.

  11. Carbon nanotube switches for memory, RF communications and sensing applications, and methods of making the same

    Science.gov (United States)

    Kaul, Anupama B. (Inventor); Wong, Eric W. (Inventor); Baron, Richard L. (Inventor); Epp, Larry (Inventor)

    2008-01-01

    Switches having an in situ grown carbon nanotube as an element thereof, and methods of fabricating such switches. A carbon nanotube is grown in situ in mechanical connection with a conductive substrate, such as a heavily doped silicon wafer or an SOI wafer. The carbon nanotube is electrically connected at one location to a terminal. At another location of the carbon nanotube there is situated a pull electrode that can be used to elecrostatically displace the carbon nanotube so that it selectively makes contact with either the pull electrode or with a contact electrode. Connection to the pull electrode is sufficient to operate the device as a simple switch, while connection to a contact electrode is useful to operate the device in a manner analogous to a relay. In various embodiments, the devices disclosed are useful as at least switches for various signals, multi-state memory, computational devices, and multiplexers.

  12. Carbon Nanotubes Used in Electroanalysis

    Science.gov (United States)

    Hu, C. G.; Feng, B.

    The fabrication of the carboxyl-modified CNT electrode was described. The electroanalytical investigation of sulfadiazine has been conducted in alkaline aqueous solution at the CNT electrode by voltammetry. Highly reproducible and well-defined cyclic voltammograms were obtained for sulfadiazine with a very good signal to background (S/B) ratio. However, no fouling of the electrode was observed at the CNT electrode within the experimental period of several hours, which illustrated that the CNT electrode was much better than traditional electrodes. Meanwhile, the detection of trace sulfadiazine in milk was also conducted by cyclic voltammetry with satisfactory ratio of recovery, indicating that the nanotube electrode can be used in routine monitoring of sulfadiazine residues in food.

  13. Torsional Electromechanics of Carbon Nanotubes

    Science.gov (United States)

    Joselevich, Ernesto; Cohen-Karni, Tzahi; Segev, Lior; Srur-Lavi, Onit; Cohen, Sidney R.

    2007-03-01

    Carbon nanotubes are known to be distinctly metallic or semiconducting depending on their diameter and chirality. Here we show that continuously varying the chirality by mechanical torsion can induce conductance oscillations, which can be attributed to metal-semiconductor periodic transitions. The phenomenon is observed in multi-walled carbon nanotubes, where both the torque and the current are shown to be carried predominantly by the outermost wall. The oscillation period with torsion is consistent with the theoretical shifting of the corners of the first Brillouin zone of graphene across different subbands allowed in the nanotube. Beyond a critical torsion, the conductance irreversibly drops due to torsional failure, allowing us to determine the torsional strength of carbon nanotubes. Our experiments indicate that carbon nanotubes could be used as self-sensing torsional springs for nanoelectromechanical systems (NEMS). [1] E. Joselevich, Twisting nanotubes: From torsion to chirality, ChemPhysChem 2006, 7, 1405. [2] T. Cohen-Karni, L. Segev, O. Srur-Lavi, S. R. Cohen, E. Joselevich, Torsional electromechanical quantum oscillations in carbon nanotubes, Nature Nanotechnology, 2006, 1, 36.

  14. Conductivity of transparent electrodes made from interacting nanotubes

    Science.gov (United States)

    Maillaud, Laurent; Zakri, Cécile; Ly, Isabelle; Pénicaud, Alain; Poulin, Philippe

    2013-12-01

    Interactions in carbon nanotube (CNT) dispersions alter the morphology of films made from such dispersions. Weak attractive interactions induce an enhancement of the electrical conductivity. This phenomenon is observed in thin films that lie in a near percolated regime. Strong interactions instead induce a decrease of conductivity. In spite of strong morphological differences, the conductivity of thick films, away from percolated regimes, do not depend on interactions between the CNTs. These experiments support a recent theoretical scenario of the percolation of interacting rods and provide guidance for the optimal formulations of CNT inks in transparent electrode applications.

  15. Functionalization of Carbon Nanotubes

    Science.gov (United States)

    Khare, Bishun N. (Inventor); Meyyappan, Meyya (Inventor)

    2009-01-01

    Method and system for functionalizing a collection of carbon nanotubes (CNTs). A selected precursor gas (e.g., H2 or F2 or CnHm) is irradiated to provide a cold plasma of selected target species particles, such as atomic H or F, in a first chamber. The target species particles are d irected toward an array of CNTs located in a second chamber while suppressing transport of ultraviolet radiation to the second chamber. A CNT array is functionalized with the target species particles, at or below room temperature, to a point of saturation, in an exposure time interval no longer than about 30 sec. *Discrimination against non-target species is provided by (i) use of a target species having a lifetime that is much greater than a lifetime of a non-target species and/or (2) use of an applied magnetic field to discriminate between charged particle trajectories for target species and for non-target species.

  16. Carbon nanotube optical mirrors

    Science.gov (United States)

    Chen, Peter C.; Rabin, Douglas

    2015-01-01

    We report the fabrication of imaging quality optical mirrors with smooth surfaces using carbon nanotubes (CNT) embedded in an epoxy matrix. CNT/epoxy is a multifunctional composite material that has sensing capabilities and can be made to incorporate self-actuation. Moreover, as the precursor is a low density liquid, large and lightweight mirrors can be fabricated by processes such as replication, spincasting, and three-dimensional printing. Therefore, the technology holds promise for the development of a new generation of lightweight, compact "smart" telescope mirrors with figure sensing and active or adaptive figure control. We report on measurements made of optical and mechanical characteristics, active optics experiments, and numerical modeling. We discuss possible paths for future development.

  17. Carbon Nanotube Electron Gun

    Science.gov (United States)

    Nguyen, Cattien V. (Inventor); Ribaya, Bryan P. (Inventor)

    2013-01-01

    An electron gun, an electron source for an electron gun, an extractor for an electron gun, and a respective method for producing the electron gun, the electron source and the extractor are disclosed. Embodiments provide an electron source utilizing a carbon nanotube (CNT) bonded to a substrate for increased stability, reliability, and durability. An extractor with an aperture in a conductive material is used to extract electrons from the electron source, where the aperture may substantially align with the CNT of the electron source when the extractor and electron source are mated to form the electron gun. The electron source and extractor may have alignment features for aligning the electron source and the extractor, thereby bringing the aperture and CNT into substantial alignment when assembled. The alignment features may provide and maintain this alignment during operation to improve the field emission characteristics and overall system stability of the electron gun.

  18. Carbon nanotube biconvex microcavities

    Energy Technology Data Exchange (ETDEWEB)

    Butt, Haider, E-mail: h.butt@bham.ac.uk; Ahmed, Rajib [Nanotechnology Laboratory, School of Mechanical Engineering, University of Birmingham, Birmingham B15 2TT (United Kingdom); Yetisen, Ali K.; Yun, Seok Hyun [Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, 50 Blossom Street, Boston, Massachusetts 02114 (United States); Dai, Qing [National Center for Nanoscience and Technology, Beijing 100190 (China)

    2015-03-23

    Developing highly efficient microcavities with predictive narrow-band resonance frequencies using the least amount of material will allow the applications in nonlinear photonic devices. We have developed a microcavity array that comprised multi-walled carbon nanotubes (MWCNT) organized in a biconvex pattern. The finite element model allowed designing microcavity arrays with predictive transmission properties and assessing the effects of the microarray geometry. The microcavity array demonstrated negative index and produced high Q factors. 2–3 μm tall MWCNTs were patterned as biconvex microcavities, which were separated by 10 μm in an array. The microcavity was iridescent and had optical control over the diffracted elliptical patterns with a far-field pattern, whose properties were predicted by the model. It is anticipated that the MWCNT biconvex microcavities will have implications for the development of highly efficient lenses, metamaterial antennas, and photonic circuits.

  19. Molybdenum Disulfide Sheathed Carbon Nanotubes

    Institute of Scientific and Technical Information of China (English)

    Xu Chun SONG; Zhu De XU; Yi Fan ZHENG; Gui HAN; Bo LIU; Wei Xiang CHEN

    2004-01-01

    Single and double layered MoS2-coated multiwalled carbon nanotubes (MWCNs) were successfully prepared by pyrolyzing (NH4)2MoS4-coated multiwalled carbon nanotubes in an H2 atmosphere at 900℃. MoS2-coated MWCNs would be expected to have different tribological and mechanical properties compared to MoS2, so it may have potential applications in many fields.

  20. Selective functionalization of carbon nanotubes

    Science.gov (United States)

    Strano, Michael S. (Inventor); Usrey, Monica (Inventor); Barone, Paul (Inventor); Dyke, Christopher A. (Inventor); Tour, James M. (Inventor); Kittrell, W. Carter (Inventor); Hauge, Robert H. (Inventor); Smalley, Richard E. (Inventor)

    2009-01-01

    The present invention is directed toward methods of selectively functionalizing carbon nanotubes of a specific type or range of types, based on their electronic properties, using diazonium chemistry. The present invention is also directed toward methods of separating carbon nanotubes into populations of specific types or range(s) of types via selective functionalization and electrophoresis, and also to the novel compositions generated by such separations.