WorldWideScience

Sample records for nanotube array electrode

  1. Coated carbon nanotube array electrodes

    Science.gov (United States)

    Ren, Zhifeng [Newton, MA; Wen, Jian [Newton, MA; Chen, Jinghua [Chestnut Hill, MA; Huang, Zhongping [Belmont, MA; Wang, Dezhi [Wellesley, MA

    2008-10-28

    The present invention provides conductive carbon nanotube (CNT) electrode materials comprising aligned CNT substrates coated with an electrically conducting polymer, and the fabrication of electrodes for use in high performance electrical energy storage devices. In particular, the present invention provides conductive CNTs electrode material whose electrical properties render them especially suitable for use in high efficiency rechargeable batteries. The present invention also provides methods for obtaining surface modified conductive CNT electrode materials comprising an array of individual linear, aligned CNTs having a uniform surface coating of an electrically conductive polymer such as polypyrrole, and their use in electrical energy storage devices.

  2. Density controlled carbon nanotube array electrodes

    Science.gov (United States)

    Ren, Zhifeng F [Newton, MA; Tu, Yi [Belmont, MA

    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.

  3. Biochips Containing Arrays of Carbon-Nanotube Electrodes

    Science.gov (United States)

    Li, Jun; Meyyappan, M.; Koehne, Jessica; Cassell, Alan; Chen, Hua

    2008-01-01

    Biochips containing arrays of nanoelectrodes based on multiwalled carbon nanotubes (MWCNTs) are being developed as means of ultrasensitive electrochemical detection of specific deoxyribonucleic acid (DNA) and messenger ribonucleic acid (mRNA) biomarkers for purposes of medical diagnosis and bioenvironmental monitoring. In mass production, these biochips could be relatively inexpensive (hence, disposable). These biochips would be integrated with computer-controlled microfluidic and microelectronic devices in automated hand-held and bench-top instruments that could be used to perform rapid in vitro genetic analyses with simplified preparation of samples. Carbon nanotubes are attractive for use as nanoelectrodes for detection of biomolecules because of their nanoscale dimensions and their chemical properties.

  4. Ti/TiO 2 nanotube array electrode as a new sensor to ...

    Indian Academy of Sciences (India)

    The Ti/TiO2 nanotube array (Ti-NTA) electrode was prepared by anodizing of the Ti foil ... and the pH=3.0 and =1.0 V (vs. reference electrode) were determined as the ... It was found that the photocurrent of EG was linearly dependent on the ...

  5. Fabrication of nickel hydroxide electrodes with open-ended hexagonal nanotube arrays for high capacitance supercapacitors.

    Science.gov (United States)

    Wu, Mao-Sung; Huang, Kuo-Chih

    2011-11-28

    A nickel hydroxide electrode with open-ended hexagonal nanotube arrays, prepared by hydrolysis of nickel chloride in the presence of hexagonal ZnO nanorods, shows a very high capacitance of 1328 F g(-1) at a discharge current density of 1 A g(-1) due to the significantly improved ion transport.

  6. Highly stable palladium-loaded TiO{sub 2} nanotube array electrode for the electrocatalytic hydrodehalogenation of polychlorinated biphenyls

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Chunyue; Wu, Juan; Xin, Yanjun [Qingdao Agricultural University, Qingdao (China); Han, Yanhe [Beijing Institute of Petrochemical Technology, Beijing (China)

    2015-06-15

    Palladized TiO{sub 2} nanotube array electrode was prepared for the electrocatalytic hydrodehalogenation (HDH) of 2,4,5-trichlorobiphenyl (2,4,5-PCB). The TiO{sub 2} nanotube array electrode was successfully fabricated by anodic oxidation method, and Pd was loaded onto the TiO{sub 2} nanotubes by electrochemical deposition. The morphology and structure of the nanotube array electrodes with and without Pd catalysts were evaluated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The results showed that the diameters and lengths of the TiO{sub 2} nanotubes were 30-50 nm and 200-400 nm, respectively. The particle size of the Pd was about 12 nm. Electrocatalytic HDH of 2,4,5-PCB with the Pd/TiO{sub 2} nanotube array electrode was performed in H-cell reactor. Under a constant potential of -1.0 V, the HDH efficiency of 2,4,5-PCB was 90% and the biphenyl yield was 83% (15% current efficiency) within 180min at the Pd/TiO{sub 2} nanotube array electrode. Compared with the Pd/Ti electrode, the Pd/TiO{sub 2} nanotube array electrode exhibited higher HDH efficiency and stability. Additionally, the effect of the primary HDH factors was also investigated.

  7. 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.

  8. Polyaniline nanowire array encapsulated in titania nanotubes as a superior electrode for supercapacitors

    Science.gov (United States)

    Xie, Keyu; Li, Jie; Lai, Yanqing; Zhang, Zhi'an; Liu, Yexiang; Zhang, Guoge; Huang, Haitao

    2011-05-01

    Conducting polymer with 1D nanostructure exhibits excellent electrochemical performances but a poor cyclability that limits its use in supercapacitors. In this work, a novel composite electrode made of polyaniline nanowire-titania nanotube array was synthesized via a simple and inexpensive electrochemical route by electropolymerizing aniline onto an anodized titania nanotube array. The specific capacitance was as high as 732 F g-1 at 1 A g-1, which remained at 543 F g-1 when the current density was increased by 20 times. 74% of the maximum energy density (36.6 Wh kg-1) was maintained even at a high power density of 6000 W kg-1. An excellent long cycle life of the electrode was observed with a retention of ~86% of the initial specific capacitance after 2000 cycles. The good electrochemical performance was attributed to the unique microstructure of the electrode with disordered PANI nanowire arrays encapsulated inside the TiO2 nanotubes, providing high surface area, fast diffusion path for ions and long-term cycle stability. Such a nanocomposite electrode is attractive for supercapacitor applications.

  9. Visible light photoelectrocatalysis with salicylic acid-modified TiO2 nanotube array electrode for p-nitrophenol degradation

    International Nuclear Information System (INIS)

    Wang Xin; Zhao Huimin; Quan Xie; Zhao Yazhi; Chen Shuo

    2009-01-01

    This research focused on immersion method synthesis of visible light active salicylic acid (SA)-modified TiO 2 nanotube array electrode and its photoelectrocatalytic (PEC) activity. The SA-modified TiO 2 nanotube array electrode was synthesized by immersing in SA solution with an anodized TiO 2 nanotube array electrode. Scanning electron microscope (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR), UV-vis diffuse reflectance spectrum (DRS), and Surface photovoltage (SPV) were used to characterize this electrode. It was found that SA-modified TiO 2 nanotube array electrode absorbed well into visible region and exhibited enhanced visible light PEC activity on the degradation of p-nitrophenol (PNP). The degradation efficiencies increased from 63 to 100% under UV light, and 79-100% under visible light (λ > 400 nm), compared with TiO 2 nanotube array electrode. The enhanced PEC activity of SA-modified TiO 2 nanotube array electrode was attributed to the amount of surface hydroxyl groups introduced by SA-modification and the extension of absorption wavelength range.

  10. electrode array

    African Journals Online (AJOL)

    PROF EKWUEME

    A geoelectric investigation employing vertical electrical soundings (VES) using the Ajayi - Makinde Two-Electrode array and the ... arrangements used in electrical D.C. resistivity survey. These include ..... Refraction Tomography to Study the.

  11. Oriented Polyaniline Nanowire Arrays Grown on Dendrimer (PAMAM) Functionalized Multiwalled Carbon Nanotubes as Supercapacitor Electrode Materials.

    Science.gov (United States)

    Jin, Lin; Jiang, Yu; Zhang, Mengjie; Li, Honglong; Xiao, Linghan; Li, Ming; Ao, Yuhui

    2018-04-19

    At present, PANI/MWNT composites have been paid more attention as promising electrode materials in supercapacitors. Yet some shortcomings still limit the widely application of PANI/MWNT electrolytes. In this work, in order to improve capacitance ability and long-term stability of electrode, a multi-amino dendrimer (PAMAM) had been covalently linked onto multi-walled carbon nanotubes (MWNT) as a bridge to facilitating covalent graft of polyaniline (PANI), affording P-MWNT/PANI electrode composites for supercapacitor. Surprisingly, ordered arrays of PANI nanowires on MWNT (setaria-like morphology) had been observed by scanning electron microscopy (SEM). Electrochemical properties of P-MWNT/PANI electrode had been characterized by cyclic voltammetry (CV) and galvanostatic charge-discharge technique. The specific capacitance and long cycle life of P-MWNT-PANI electrode material were both much higher than MWNT/PANI. These interesting results indicate that multi-amino dendrimer, PAMAM, covalently linked on MWNT provides more reaction sites for in-situ polymerization of ordered PANI, which could efficiently shorten the ion diffusion length in electrolytes and lead to making fully use of conducting materials.

  12. Vertically Aligned Carbon Nanotube Arrays as Efficient Supports for Faradaic Capacitive Electrodes

    Science.gov (United States)

    Oguntoye, Moses; Holleran, Mary-Kate; Roberts, Katherine; Pesika, Noshir

    Supercapacitors are notable for their ability to deliver energy at higher power (compared to batteries) and store energy at higher density (compared to capacitors) as well as exhibit a long cycle life. In our efforts to further the development of supercapacitors, our focus is on using vertically aligned carbon nanotubes (VACNT) as supports for faradaic capacitive electrode materials. The objective is to develop electrodes functioning in an inexpensive aqueous environment with small potential windows, that store energy at a higher density than carbon materials alone. We describe the different approaches explored to overcome the challenges of non-uniform deposition, poor wetting and array collapse. Materials that are electrochemically anchored to VACNT supports include NiCo2O4, VOx, Fe2O3 and Co-Mn mixed oxides. In each case, the specific capacitance obtained using the VACNT arrays as supports is significantly more than that obtained by direct deposition onto current collectors or by using VACNT alone. The ease of VACNT growth and the degree of coating control achievable using electrodeposition means there is much potential in exploring them as supports for capacitive electrode materials.

  13. Fabrication of nano-electrode arrays of free-standing carbon nanotubes on nano-patterned substrate by imprint method

    Energy Technology Data Exchange (ETDEWEB)

    Chang, W.S., E-mail: paul@kimm.re.kr [Department of Nano Mechanics, Korea Institute of Machinery and Materials, 104 Sinseongno, Yuseong-gu Daejeon 305-343 (Korea, Republic of); Kim, J.W. [Gyeongbuk Hybrid Technology Institute, 36 Goeyeon-dong, Yeongcheon, Gyeongbuk 770-170 (Korea, Republic of); Choi, D.G. [Department of Nano Mechanics, Korea Institute of Machinery and Materials, 104 Sinseongno, Yuseong-gu Daejeon 305-343 (Korea, Republic of); Han, C.S. [Gyeongbuk Hybrid Technology Institute, 36 Goeyeon-dong, Yeongcheon, Gyeongbuk 770-170 (Korea, Republic of)

    2011-01-15

    The synthesis of isolated carbon nanotubes with uniform outer diameters and ordered spacing over wafer-scale areas was investigated for fabrication of nano-electrode arrays on silicon wafers for field emission and sensor devices. Multi-walled carbon nanotubes (MWCNTs) were grown on TiN electrode layer with iron catalyst patterned by nano-imprint lithography (NIL), which allows the precise placement of individual CNTs on a substrate. The proposed techniques, including plasma-enhanced chemical vapor deposition (PECVD) and NIL, are simple, inexpensive, and reproducible methods for fabrication of nano-scale devices in large areas. The catalyst patterns were defined by an array of circles with 200 nm in diameter, and variable lengths of pitch. The nano-patterned master and Fe catalyst were observed with good pattern fidelity over a large area by atomic force microscope (AFM) and scanning electron microscopy (SEM). Nano-electrodes of MWCNTs had diameters ranging from 50 nm to 100 nm and lengths of about 300 nm. Field emission tests showed the reducing ignition voltage as the geometry of nanotube arrays was controlled by catalyst patterning. These results showed a wafer-scale approach to the control of the size, pitch, and position of nano-electrodes of nanotubes for various applications including electron field-emission sources, electrochemical probes, functionalized sensor elements, and so on.

  14. Fabrication of PANI/C-TiO2 Composite Nanotube Arrays Electrode for Supercapacitor

    Directory of Open Access Journals (Sweden)

    Chengcheng Zhang

    2015-01-01

    Full Text Available Polyaniline/carbon doped TiO2 composite nanotube arrays (PANI/C-TiO2 NTAs have been prepared successfully by electrodepositing PANI in C-TiO2 NTAs which were prepared by directly annealing the as-anodized TiO2 NTAs under Ar atmosphere. The organic residual in the TiO2 NTAs during the process of anodization acts as carbon source and is carbonized in Ar atmosphere to manufacture the C-TiO2 NTAs. The specific capacitance of the PANI/C-TiO2 electrode is 120.8 mF cm−2 at a current density of 0.1 mA cm−2 and remains 104.3 mF cm−2 at a current density of 2 mA cm−2 with the calculated rate performance of 86.3%. After 5000 times of charge-discharge cycling at a current density of 0.2 mA cm−2, the specific capacitance retains 88.7% compared to the first cycle. All these outstanding performances of the as-prepared PANI/C-TiO2 NTAs indicate it will be a promising electrode for supercapacitor.

  15. 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.

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

    International Nuclear Information System (INIS)

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

    2015-01-01

    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. (paper)

  17. Oriented nanotube electrodes for lithium ion batteries and supercapacitors

    Science.gov (United States)

    Frank, Arthur J.; Zhu, Kai; Wang, Qing

    2013-03-05

    An electrode having an oriented array of multiple nanotubes is disclosed. Individual nanotubes have a lengthwise inner pore defined by interior tube walls which extends at least partially through the length of the nanotube. The nanotubes of the array may be oriented according to any identifiable pattern. Also disclosed is a device featuring an electrode and methods of fabrication.

  18. 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.

  19. Vertically Aligned Co9 S8 Nanotube Arrays onto Graphene Papers as High-Performance Flexible Electrodes for Supercapacitors.

    Science.gov (United States)

    Xiong, Dongbin; Li, Xifei; Bai, Zhimin; Li, Jianwei; Han, Yan; Li, Dejun

    2018-02-16

    Paper-like electrodes are emerging as a new category of advanced electrodes for flexible supercapacitors (SCs). Graphene, a promising two-dimensional material with high conductivity, can be easily processed into papers. Here, we report a rational design of flexible architecture with Co 9 S 8 nanotube arrays (NAs) grown onto graphene paper (GP) via a facile two-step hydrothermal method. When employed as flexible free-standing electrode for SCs, the proposed architectured Co 9 S 8 /GPs exhibits superior electrochemical performance with ultrahigh capacitance and outstanding rate capability (469 F g -1 at 10 A g -1 ). These results demonstrate that the new nanostructured Co 9 S 8 /GPs can be potentially applied in high performance flexible supercapacitors. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Ni nanotube array-based electrodes by electrochemical alloying and de-alloying for efficient water splitting.

    Science.gov (United States)

    Teng, Xue; Wang, Jianying; Ji, Lvlv; Lv, Yaokang; Chen, Zuofeng

    2018-05-17

    The design of cost-efficient earth-abundant catalysts with superior performance for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is extremely important for future renewable energy production. Herein, we report a facile strategy for constructing Ni nanotube arrays (NTAs) on a Ni foam (NF) substrate through cathodic deposition of NiCu alloy followed by anodic stripping of metallic Cu. Based on Ni NTAs, the as-prepared NiSe2 NTA electrode by NiSe2 electrodeposition and the NiFeOx NTA electrode by dipping in Fe3+ solution exhibit excellent HER and OER performance in alkaline conditions. In these systems, Ni NTAs act as a binder-free multifunctional inner layer to support the electrocatalysts, offer a large specific surface area and serve as a fast electron transport pathway. Moreover, an alkaline electrolyzer has been constructed using NiFeOx NTAs as the anode and NiSe2 NTAs as the cathode, which only demands a cell voltage of 1.78 V to deliver a water-splitting current density of 500 mA cm-2, and demonstrates remarkable stability during long-term electrolysis. This work provides an attractive method for the design and fabrication of nanotube array-based catalyst electrodes for highly efficient water-splitting.

  1. Microstructure and pseudocapacitive properties of electrodes constructed of oriented NiO-TiO2 nanotube arrays.

    Science.gov (United States)

    Kim, Jae-Hun; Zhu, Kai; Yan, Yanfa; Perkins, Craig L; Frank, Arthur J

    2010-10-13

    We report on the synthesis and electrochemical properties of oriented NiO-TiO(2) nanotube (NT) arrays as electrodes for supercapacitors. The morphology of the films prepared by electrochemically anodizing Ni-Ti alloy foils was characterized by scanning and transmission electron microscopies, X-ray diffraction, and photoelectron spectroscopies. The morphology, crystal structure, and composition of the NT films were found to depend on the preparation conditions (anodization voltage and postgrowth annealing temperature). Annealing the as-grown NT arrays to a temperature of 600 °C transformed them from an amorphous phase to a mixture of crystalline rock salt NiO and rutile TiO(2). Changes in the morphology and crystal structure strongly influenced the electrochemical properties of the NT electrodes. Electrodes composed of NT films annealed at 600 °C displayed pseudocapacitor (redox-capacitor) behavior, including rapid charge/discharge kinetics and stable long-term cycling performance. At similar film thicknesses and surface areas, the NT-based electrodes showed a higher rate capability than the randomly packed nanoparticle-based electrodes. Even at the highest scan rate (500 mV/s), the capacitance of the NT electrodes was not much smaller (within 12%) than the capacitance measured at the slowest scan rate (5 mV/s). The faster charge/discharge kinetics of NT electrodes at high scan rates is attributed to the more ordered NT film architecture, which is expected to facilitate electron and ion transport during the charge-discharge reactions.

  2. In situ synthesis of oriented NiS nanotube arrays on FTO as high-performance counter electrode for dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yan, E-mail: liyan-nwnu@163.com [Key Laboratory of Atomic and Molecular Physics & Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou, 730070 (China); Chang, Yin [Key Laboratory of Atomic and Molecular Physics & Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou, 730070 (China); Zhao, Yun [Laboratory of Clean Energy Chemistry and Materials, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); Wang, Jian; Wang, Cheng-wei [Key Laboratory of Atomic and Molecular Physics & Functional Materials of Gansu Province, College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou, 730070 (China)

    2016-09-15

    Oriented nickel sulfide (NiS) nanotube arrays were successfully in-situ fabricated on conductive glass substrate and used directly as counter electrode for dye-sensitized solar cells without any post-processing. Compared with Pt counter electrode, for the beneficial effect of electronic transport along the axial direction through the arrays to the substrate, oriented NiS nanotube arrays exhibit both higher electrocatalytic activity for I{sub 3}{sup −} reduction and better electrochemical stability, resulting in a significantly improved power conversion efficiency of 9.8%. Such in-situ grown oriented sulfide semiconductor nanotube arrays is expected to lead a new class structure of composites for highly efficient cathode materials. - Highlights: • In-situ synthesis strategy was proposed to construct oriented NiS nanotube arrays. • Such oriented tube nanostructure benefits the electronic transport along the axial direction of the arrays. • As CE of DSSCs, NiS nanotube arrays exhibit both higher efficiency (9.8%) and electrochemical stability than Pt.

  3. Supported noble metals on hydrogen-treated TiO2 nanotube arrays as highly ordered electrodes for fuel cells.

    Science.gov (United States)

    Zhang, Changkun; Yu, Hongmei; Li, Yongkun; Gao, Yuan; Zhao, Yun; Song, Wei; Shao, Zhigang; Yi, Baolian

    2013-04-01

    Hydrogen-treated TiO2 nanotube (H-TNT) arrays serve as highly ordered nanostructured electrode supports, which are able to significantly improve the electrochemical performance and durability of fuel cells. The electrical conductivity of H-TNTs increases by approximately one order of magnitude in comparison to air-treated TNTs. The increase in the number of oxygen vacancies and hydroxyl groups on the H-TNTs help to anchor a greater number of Pt atoms during Pt electrodeposition. The H-TNTs are pretreated by using a successive ion adsorption and reaction (SIAR) method that enhances the loading and dispersion of Pt catalysts when electrodeposited. In the SIAR method a Pd activator can be used to provide uniform nucleation sites for Pt and leads to increased Pt loading on the H-TNTs. Furthermore, fabricated Pt nanoparticles with a diameter of 3.4 nm are located uniformly around the pretreated H-TNT support. The as-prepared and highly ordered electrodes exhibit excellent stability during accelerated durability tests, particularly for the H-TNT-loaded Pt catalysts that have been annealed in ultrahigh purity H2 for a second time. There is minimal decrease in the electrochemical surface area of the as-prepared electrode after 1000 cycles compared to a 68 % decrease for the commercial JM 20 % Pt/C electrode after 800 cycles. X-ray photoelectron spectroscopy shows that after the H-TNT-loaded Pt catalysts are annealed in H2 for the second time, the strong metal-support interaction between the H-TNTs and the Pt catalysts enhances the electrochemical stability of the electrodes. Fuel-cell testing shows that the power density reaches a maximum of 500 mWcm(-2) when this highly ordered electrode is used as the anode. When used as the cathode in a fuel cell with extra-low Pt loading, the new electrode generates a specific power density of 2.68 kWg(Pt) (-1) . It is indicated that H-TNT arrays, which have highly ordered nanostructures, could be used as ordered electrode supports

  4. A pH sensor based on the TiO{sub 2} nanotube array modified Ti electrode

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Rongrong; Xu Meizhu [Ministry of Education Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection for Food Safety, Department of Chemistry, Fuzhou University, 523 Gongye Road, Fuzhou 350002, Fujian (China); Wang Jian, E-mail: jwang@fzu.edu.c [Ministry of Education Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection for Food Safety, Department of Chemistry, Fuzhou University, 523 Gongye Road, Fuzhou 350002, Fujian (China); Chen Guonan, E-mail: guonanchen@126.co [Ministry of Education Key Laboratory of Analysis and Detection for Food Safety, Fujian Provincial Key Laboratory of Analysis and Detection for Food Safety, Department of Chemistry, Fuzhou University, 523 Gongye Road, Fuzhou 350002, Fujian (China)

    2010-08-01

    In this paper, a novel solid state pH sensor was fabricated by anodization of titanium substrate electrode. The relationship between pH sensitivity and hydrophilicity or surface morphology of TiO{sub 2} film was investigated. Amorphous TiO{sub 2} nanotube has better pH response than anatase TiO{sub 2} nanotube. After being irradiated by ultraviolet light (UV), the potential response of the electrode modified by amorphous TiO{sub 2} nanotube was close to Nernst equation (59 mV/pH). SEM, XRD, and XPS were used to characterize electrodes. Possible mechanism was discussed by analyzing surface hydroxyl groups, crystal structure and hydrophilicity of the electrodes. The electrode has been used to detect some kinds of soft drinks and shows good response.

  5. High-performance and renewable supercapacitors based on TiO2 nanotube array electrodes treated by an electrochemical doping approach

    International Nuclear Information System (INIS)

    Wu, Hui; Li, Dongdong; Zhu, Xufei; Yang, Chunyan; Liu, Dongfang; Chen, Xiaoyuan; Song, Ye; Lu, Linfeng

    2014-01-01

    Although one-dimensional anodic TiO 2 nanotube arrays have shown promise as supercapacitor electrode materials, their poor electronic conductivity embarrasses the practical applications. Here, we develop a simple electrochemical doping method to significantly improve the electronic conductivity and the electrochemical performances of TiO 2 nanotube electrodes. These TiO 2 nanotube electrodes treated by the electrochemical hydrogenation doping (TiO 2 -H) exhibit a very high average specific capacitance of 20.08 mF cm −2 at a current density of 0.05 mA cm −2 , ∼20 times more than the pristine TiO 2 nanotube electrodes. The improved electrochemical performances can be attributed to ultrahigh conductivity of TiO 2 -H due to the introduction of interstitial hydrogen ions and oxygen vacancies by the doping. The supercapacitor device assembled by the doped electrodes delivers a specific capacitance of 5.42 mF cm −2 and power density of 27.66 mW cm −2 , on average, at the current density of 0.05 mA cm −2 . The device also shows an outstanding rate capability with 60% specific capacitance retained when the current density increases from 0.05 to 4.00 mA cm −2 . More interestingly, the electrochemical performances of the supercapacitor after cycling can be recovered by the same doping process. This strategy boosts the performances of the supercapacitor, especially cycling stability

  6. Preparation of CuInS{sub 2}/TiO{sub 2} nanotube heterojunction arrays electrode and investigation of its photoelectrochemical properties

    Energy Technology Data Exchange (ETDEWEB)

    Li, Tingting [School of Environmental Science and Technology, State Key Laboratory of Fine Chemical, Key Laboratory of Industrial Ecology and Environmental Engineering of Ministry of Education, Dalian University of Technology, Dalian 116024, Liaoning (China); College of Civil Engineering and Architecture, Liaoning Technical University, Fuxin 123000 (China); Li, Xinyong, E-mail: xyli@dlut.edu.cn [School of Environmental Science and Technology, State Key Laboratory of Fine Chemical, Key Laboratory of Industrial Ecology and Environmental Engineering of Ministry of Education, Dalian University of Technology, Dalian 116024, Liaoning (China); Zhao, Qidong; Teng, Wei [School of Environmental Science and Technology, State Key Laboratory of Fine Chemical, Key Laboratory of Industrial Ecology and Environmental Engineering of Ministry of Education, Dalian University of Technology, Dalian 116024, Liaoning (China)

    2014-11-15

    Graphical abstract: Schematic illustration of the synthesis steps of CuInS{sub 2}/TiO{sub 2} heterojunction arrays electrode. - Highlights: • CuInS{sub 2}/TiO{sub 2} nanotube heterojunction arrays electrode was successfully fabricated via a modified SILAR method. • Morphology, chemical compositions and the photoelectrochemical properties were studied. • The formed heterojunction structure is demonstrated as n–n type heterojunction. - Abstract: CuInS{sub 2}/TiO{sub 2} nanotube heterojunction arrays electrode was synthesized via a modified successive ionic layer adsorption and reaction (SILAR) method. The morphology, crystalline structure and chemical composition of the composite electrode were characterized with field-emission scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectra (XPS), respectively. The optical properties were investigated by UV–vis diffusion reflection spectra (DRS) and photoluminescence (PL) spectra as well as the photoelectrochemical measurements. Significantly enhanced photoelectrochemical properties of CuInS{sub 2}/TiO{sub 2} NTs electrode were observed under visible light irradiation, which could be attributed to the high absorption coefficient of CuInS{sub 2} in visible region and the heterostructure formed between CuInS{sub 2} and TiO{sub 2}.

  7. Co(OH)2/RGO/NiO sandwich-structured nanotube arrays with special surface and synergistic effects as high-performance positive electrodes for asymmetric supercapacitors.

    Science.gov (United States)

    Xu, Han; Zhang, Chi; Zhou, Wen; Li, Gao-Ren

    2015-10-28

    High power density, high energy density and excellent cycling stability are the main requirements for high-performance supercapacitors (SCs) that will be widely used for portable consumer electronics and hybrid electric vehicles. Here we investigate novel types of hybrid Co(OH)2/reduced graphene oxide (RGO)/NiO sandwich-structured nanotube arrays (SNTAs) as positive electrodes for asymmetric supercapacitors (ASCs). The synthesized Co(OH)2/RGO/NiO SNTAs exhibit a significantly improved specific capacity (∼1470 F g(-1) at 5 mV s(-1)) and excellent cycling stability with ∼98% Csp retention after 10 000 cycles because of the fast transport and short diffusion paths for electroactive species, the high utilization rate of electrode materials, and special synergistic effects among Co(OH)2, RGO, and NiO. The high-performance ASCs are assembled using Co(OH)2/RGO/NiO SNTAs as positive electrodes and active carbon (AC) as negative electrodes, and they exhibit a high energy density (115 Wh kg(-1)), a high power density (27.5 kW kg(-1)) and an excellent cycling stability (less 5% Csp loss after 10 000 cycles). This study shows an important breakthrough in the design and fabrication of multi-walled hybrid nanotube arrays as positive electrodes for ASCs.

  8. Understanding the effect of morphology on the photocatalytic activity of TiO2 nanotube array electrodes

    International Nuclear Information System (INIS)

    Adán, C.; Marugán, J.; Sánchez, E.; Pablos, C.; Grieken, R. van

    2016-01-01

    A comprehensive report on the correlation between the morphology and the photocatalytic (PC) and photoelectrocatalytic (PEC) activity of TiO 2 nanotubes (NTs) electrodes is presented. New insights are provided to support the effect of the anodization conditions on the photon-to-current efficiency of the electrodes based on the dimensional characteristics of the TiO 2 -NTs. Electrodes with promising properties based on the characterization data were scaled-up to test their activity on the PC and PEC oxidation of methanol. Results indicate that the length of the nanotubes significantly influences the photodegradation efficiency. The enhancement achieved in both PC and PEC processes with longer nanotubes can be explained by the higher surface area in contact with the electrolyte and the increase in the light absorption as the TiO 2 layer becomes thicker. However, as the length of the nanotubes increases, a reduction in the enhancement achieved by the application of a potential bias is observed. Kinetic constants of both reactions (PC and PEC) tend to get closer and the charge separation effect diminishes. In relative terms, the effect of the electric potential is more pronounced for electrodes with the shorter NTs. The reason is that once the TiO 2 layer is thick enough to absorb the available radiation, a further increase in the NTs length increases the resistance of the electrons to reach the back contact and the diffusional restrictions to the mass transport of the reactants/products along the tubes. Consequently, the existence of a compromise between reactivity and transport properties lead to the existence of an optimal NTs length.

  9. Carbon nanotube array actuators

    International Nuclear Information System (INIS)

    Geier, S; Mahrholz, T; Wierach, P; Sinapius, M

    2013-01-01

    Experimental investigations of highly vertically aligned carbon nanotubes (CNTs), also known as CNT-arrays, are the main focus of this paper. The free strain as result of an active material behavior is analyzed via a novel experimental setup. Previous test experiences of papers made of randomly oriented CNTs, also called Bucky-papers, reveal comparably low free strain. The anisotropy of aligned CNTs promises better performance. Via synthesis techniques like chemical vapor deposition (CVD) or plasma enhanced CVD (PECVD), highly aligned arrays of multi-walled carbon nanotubes (MWCNTs) are synthesized. Two different types of CNT-arrays are analyzed, morphologically first, and optically tested for their active characteristics afterwards. One type of the analyzed arrays features tube lengths of 750–2000 μm with a large variety of diameters between 20 and 50 nm and a wave-like CNT-shape. The second type features a maximum, almost uniform, length of 12 μm and a constant diameter of 50 nm. Different CNT-lengths and array types are tested due to their active behavior. As result of the presented tests, it is reported that the quality of orientation is the most decisive property for excellent active behavior. Due to their alignment, CNT-arrays feature the opportunity to clarify the actuation mechanism of architectures made of CNTs. (paper)

  10. Co(OH)2/RGO/NiO sandwich-structured nanotube arrays with special surface and synergistic effects as high-performance positive electrodes for asymmetric supercapacitors

    Science.gov (United States)

    Xu, Han; Zhang, Chi; Zhou, Wen; Li, Gao-Ren

    2015-10-01

    High power density, high energy density and excellent cycling stability are the main requirements for high-performance supercapacitors (SCs) that will be widely used for portable consumer electronics and hybrid electric vehicles. Here we investigate novel types of hybrid Co(OH)2/reduced graphene oxide (RGO)/NiO sandwich-structured nanotube arrays (SNTAs) as positive electrodes for asymmetric supercapacitors (ASCs). The synthesized Co(OH)2/RGO/NiO SNTAs exhibit a significantly improved specific capacity (~1470 F g-1 at 5 mV s-1) and excellent cycling stability with ~98% Csp retention after 10 000 cycles because of the fast transport and short diffusion paths for electroactive species, the high utilization rate of electrode materials, and special synergistic effects among Co(OH)2, RGO, and NiO. The high-performance ASCs are assembled using Co(OH)2/RGO/NiO SNTAs as positive electrodes and active carbon (AC) as negative electrodes, and they exhibit a high energy density (115 Wh kg-1), a high power density (27.5 kW kg-1) and an excellent cycling stability (less 5% Csp loss after 10 000 cycles). This study shows an important breakthrough in the design and fabrication of multi-walled hybrid nanotube arrays as positive electrodes for ASCs.High power density, high energy density and excellent cycling stability are the main requirements for high-performance supercapacitors (SCs) that will be widely used for portable consumer electronics and hybrid electric vehicles. Here we investigate novel types of hybrid Co(OH)2/reduced graphene oxide (RGO)/NiO sandwich-structured nanotube arrays (SNTAs) as positive electrodes for asymmetric supercapacitors (ASCs). The synthesized Co(OH)2/RGO/NiO SNTAs exhibit a significantly improved specific capacity (~1470 F g-1 at 5 mV s-1) and excellent cycling stability with ~98% Csp retention after 10 000 cycles because of the fast transport and short diffusion paths for electroactive species, the high utilization rate of electrode materials, and

  11. Enhanced photoelectrochemical performance of PbS sensitized Sb–SnO{sub 2}/TiO{sub 2} nanotube arrays electrode under visible light illumination

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jia; Tang, Chengli [Department of Environmental Science and Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Xu, Hao, E-mail: xuhao@mail.xjtu.edu.cn [Department of Environmental Science and Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); Yan, Wei, E-mail: yanwei@mail.xjtu.edu.cn [Department of Environmental Science and Engineering, Xi’an Jiaotong University, Xi’an 710049 (China); State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049 (China)

    2015-06-05

    Highlights: • Sb–SnO{sub 2} is used to modify TiO{sub 2} NTAs by microwave method. • PbS is employed to sensitive Sb–SnO{sub 2}/TiO{sub 2} NTAs by S-SILAR method. • Sb–SnO{sub 2} improves electrons transfer and PbS enhances visible light absorption. • The composite electrode shows enhanced photoelectrochemical properties. • The composite electrode exhibits high hydrogen evolution and high QE. - Abstract: The novel PbS sensitized Sb–SnO{sub 2}/TiO{sub 2} nanotube arrays (NTAs) composite electrode (PbS/Sb–SnO{sub 2}/TiO{sub 2} NTAs) was fabricated by microwave combined with sonication-assisted successive ionic layer adsorption and reaction technique (S-SILAR). The obtained electrodes were characterized by field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV–Vis diffuse reflectance absorption spectra techniques. Enhanced photocurrent (15.52 mA/cm{sup 2}) of the PbS/Sb–SnO{sub 2}/TiO{sub 2} NTAs electrode was observed and can be attributed to the facile photo-generated electrons transfer and enhanced charge separation efficiency. Furthermore, the PbS/Sb–SnO{sub 2}/TiO{sub 2} NTAs composite electrode shows a higher H{sub 2} production rate than the Sb–SnO{sub 2}/TiO{sub 2} NTAs electrode and PbS/TiO{sub 2} NTAs electrode. The results indicate that the PbS/Sb–SnO{sub 2}/TiO{sub 2} NTAs electrode is a promising photoanode in visible photocatalytic water splitting.

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

    International Nuclear Information System (INIS)

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

    2007-01-01

    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

  13. MnO{sub 2} nanotube and nanowire arrays by electrochemical deposition for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Xia, Hui; Feng, Jinkui; Wang, Hailong; Lai, Man On; Lu, Li [Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117576 (Singapore)

    2010-07-01

    Highly ordered MnO{sub 2} nanotube and nanowire arrays are successfully synthesized via a electrochemical deposition technique using porous alumina templates. The morphologies and microstructures of the MnO{sub 2} nanotube and nanowire arrays are investigated by field emission scanning electron microscopy and transmission electron microscopy. Electrochemical characterization demonstrates that the MnO{sub 2} nanotube array electrode has superior capacitive behaviour to that of the MnO{sub 2} nanowire array electrode. In addition to high specific capacitance, the MnO{sub 2} nanotube array electrode also exhibits good rate capability and good cycling stability, which makes it promising candidate for supercapacitors. (author)

  14. Synthesis of carbon nanotubes bridging metal electrodes

    International Nuclear Information System (INIS)

    Kotlar, M.; Vojs, M.; Marton, M.; Vesel, M.; Redhammer, R.

    2012-01-01

    In our work we demonstrate growth of carbon nanotubes that can conductively bridge the metal electrodes. The role of different catalysts was examined. Interdigitated metal electrodes are made from copper and we are using bimetal Al/Ni as catalyst for growth of carbon nanotubes. We are using this catalyst composition for growth of the single-walled carbon nanotube network. (authors)

  15. Vertically aligned carbon nanotubes for microelectrode arrays applications.

    Science.gov (United States)

    Castro Smirnov, J R; Jover, Eric; Amade, Roger; Gabriel, Gemma; Villa, Rosa; Bertran, Enric

    2012-09-01

    In this work a methodology to fabricate carbon nanotube based electrodes using plasma enhanced chemical vapour deposition has been explored and defined. The final integrated microelectrode based devices should present specific properties that make them suitable for microelectrode arrays applications. The methodology studied has been focused on the preparation of highly regular and dense vertically aligned carbon nanotube (VACNT) mat compatible with the standard lithography used for microelectrode arrays technology.

  16. Aligned Carbon Nanotubes Array by DC Glow Plasma Etching for Supercapacitor

    Directory of Open Access Journals (Sweden)

    Yongfeng Luo

    2013-01-01

    Full Text Available 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.

  17. Multiwall carbon nanotube microcavity arrays

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Rajib; Butt, Haider, E-mail: h.butt@bham.ac.uk [Nanotechnology Laboratory, School of Mechanical Engineering, University of Birmingham, Birmingham B15 2TT (United Kingdom); Rifat, Ahmmed A. [Integrated Lightwave Research Group, Department of Electrical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603 (Malaysia); Yetisen, Ali K.; Yun, Seok Hyun [Harvard Medical School and Wellman Center for Photomedicine, Massachusetts General Hospital, 65 Landsdowne Street, Cambridge, Massachusetts 02139 (United States); Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Dai, Qing [National Center for Nanoscience and Technology, Beijing 100190 (China)

    2016-03-21

    Periodic highly dense multi-wall carbon nanotube (MWCNT) arrays can act as photonic materials exhibiting band gaps in the visible regime and beyond terahertz range. MWCNT arrays in square arrangement for nanoscale lattice constants can be configured as a microcavity with predictable resonance frequencies. Here, computational analyses of compact square microcavities (≈0.8 × 0.8 μm{sup 2}) in MWCNT arrays were demonstrated to obtain enhanced quality factors (≈170–180) and narrow-band resonance peaks. Cavity resonances were rationally designed and optimized (nanotube geometry and cavity size) with finite element method. Series (1 × 2 and 1 × 3) and parallel (2 × 1 and 3 × 1) combinations of microcavities were modeled and resonance modes were analyzed. Higher order MWCNT microcavities showed enhanced resonance modes, which were red shifted with increasing Q-factors. Parallel microcavity geometries were also optimized to obtain narrow-band tunable filtering in low-loss communication windows (810, 1336, and 1558 nm). Compact series and parallel MWCNT microcavity arrays may have applications in optical filters and miniaturized optical communication devices.

  18. Pd-MnO2 nanoparticles/TiO2 nanotube arrays (NTAs) photo-electrodes photo-catalytic properties and their ability of degrading Rhodamine B under visible light.

    Science.gov (United States)

    Thabit, Mohamed; Liu, Huiling; Zhang, Jian; Wang, Bing

    2017-10-01

    Pd-MnO 2 /TiO 2 nanotube arrays (NTAs) photo-electrodes were successfully fabricated via anodization and electro deposition subsequently; the obtained Pd-MnO 2 /TiO 2 NTAs photo electrodes were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and characterized accordingly. Moreover, the light harvesting and absorption properties were investigated via ultraviolet-visible diffuse reflectance spectrum (DRS); photo degradation efficiency was investigated via analyzing the photo catalytic degradation of Rhodamine B under visible illumination (xenon light). The performed analyses illustrated that Pd-MnO 2 codoped particles were successfully deposited onto the surface of the TiO 2 nanotube arrays; DRS results showed significant improvement in visible light absorption which was between 400 and 700nm. Finally, the photo catalytic degradation efficiency results of the designated organic pollutant (Rhodamine B) illustrated a superior photocatalytic (PC) efficiency of approximately 95% compared to the bare TiO 2 NTAs, which only exhibited a photo catalytic degradation efficiency of approximately 61%, thus it indicated the significant enhancement of the light absorption properties of fabricated photo electrodes and their yield of OH radicals. Copyright © 2017. Published by Elsevier B.V.

  19. Graphene quantum dots-carbon nanotube hybrid arrays for supercapacitors

    Science.gov (United States)

    Hu, Yue; Zhao, Yang; Lu, Gewu; Chen, Nan; Zhang, Zhipan; Li, Hui; Shao, Huibo; Qu, Liangti

    2013-05-01

    Graphene quantum dots (GQDs) have been successfully deposited onto aligned carbon nanotubes (CNTs) by a benign electrochemical method and the capacitive properties of the as-formed GQD/CNT hybrid arrays were evaluated in symmetrical supercapacitors. It was found that supercapacitors fabricated from GQD/CNT hybrid arrays exhibited a high capacitance of 44 mF cm-2, representing a more than 200% improvement over that of bare CNT electrodes.

  20. Direct growth of metal-organic frameworks thin film arrays on glassy carbon electrode based on rapid conversion step mediated by copper clusters and hydroxide nanotubes for fabrication of a high performance non-enzymatic glucose sensing platform.

    Science.gov (United States)

    Shahrokhian, Saeed; Khaki Sanati, Elnaz; Hosseini, Hadi

    2018-07-30

    The direct growth of self-supported metal-organic frameworks (MOFs) thin film can be considered as an effective strategy for fabrication of the advanced modified electrodes in sensors and biosensor applications. However, most of the fabricated MOFs-based sensors suffer from some drawbacks such as time consuming for synthesis of MOF and electrode making, need of a binder or an additive layer, need of expensive equipment and use of hazardous solvents. Here, a novel free-standing MOFs-based modified electrode was fabricated by the rapid direct growth of MOFs on the surface of the glassy carbon electrode (GCE). In this method, direct growth of MOFs was occurred by the formation of vertically aligned arrays of Cu clusters and Cu(OH) 2 nanotubes, which can act as both mediator and positioning fixing factor for the rapid formation of self-supported MOFs on GCE surface. The effect of both chemically and electrochemically formed Cu(OH) 2 nanotubes on the morphological and electrochemical performance of the prepared MOFs were investigated. Due to the unique properties of the prepared MOFs thin film electrode such as uniform and vertically aligned structure, excellent stability, high electroactive surface area, and good availability to analyte and electrolyte diffusion, it was directly used as the electrode material for non-enzymatic electrocatalytic oxidation of glucose. Moreover, the potential utility of this sensing platform for the analytical determination of glucose concentration was evaluated by the amperometry technique. The results proved that the self-supported MOFs thin film on GCE is a promising electrode material for fabricating and designing non-enzymatic glucose sensors. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. A facile one-step synthesis of Mn{sub 3}O{sub 4} nanoparticles-decorated TiO{sub 2} nanotube arrays as high performance electrode for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jianfang [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Wang, Yan [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Key Laboratory of Advance Functional Materials and Devices of Anhui Province, Hefei 230009 (China); Qin, Yongqiang, E-mail: albon@hfut.edu.cn [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Key Laboratory of Advance Functional Materials and Devices of Anhui Province, Hefei 230009 (China); Yu, Cuiping [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Cui, Lihua [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); School of Materials Science and Engineering, Beifang University of Nationalities, Yinchuan 750021 (China); Shu, Xia [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Cui, Jiewu; Zheng, Hongmei; Zhang, Yong [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Key Laboratory of Advance Functional Materials and Devices of Anhui Province, Hefei 230009 (China); Wu, Yucheng, E-mail: ycwu@hfut.edu.cn [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Key Laboratory of Advance Functional Materials and Devices of Anhui Province, Hefei 230009 (China)

    2017-02-15

    Via a facile one-step chemical bath deposition route, homogeneously dispersed Mn{sub 3}O{sub 4} nanoparticles have been successfully deposited onto the inner surface of TiO{sub 2} nanotube arrays (TNAs). The content and size of Mn{sub 3}O{sub 4} can be controlled by changing the deposition time. Field emission scanning electron microscopy and transmission electron microscopy analysis reveal the morphologies structures of Mn{sub 3}O{sub 4}/TNAs composites. The crystal-line structures are characterized by the X-ray diffraction patterns and Raman spectra. X-ray photoelectron spectroscopy further confirms the valence states of the sample elements. The electrochemical properties of Mn{sub 3}O{sub 4}/TNAs electrodes are systematically investigated by the combine use of cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The resulting Mn{sub 3}O{sub 4}/TNAs electrode prepared by deposition time of 3 h shows the highest specific capacitance of 570 F g{sup −1} at a current density of 1 A g{sup −1}. And it also shows an excellent long-term cycling stability at a current density of 5 A g{sup −1}, which remaining 91.8% of the initial capacitance after 2000 cycles. Thus this kind of Mn{sub 3}O{sub 4} nanoparticles decorated TNAs may be considered as an alternative promising candidate for high performance supercapacitor electrodes. - Graphical abstract: Mn{sub 3}O{sub 4} nanoparticles have been uniformly deposited onto the inner surfaces of TiO{sub 2} nanotube arrays through a facile one-step chemical bath deposition method. As electrodes for supercapacitors, they exhibit a relatively high specific capacity and excellent cycling stability. - Highlights: • Mn{sub 3}O{sub 4} nanoparticles have been deposited onto TiO{sub 2} nanotube arrays by chemical bath deposition. • The Mn{sub 3}O{sub 4}/TNAs exhibits a highest specific capacitance of 570 F g{sup –1} at a current density of 1 A g{sup –1}. • The Mn{sub 3}O{sub 4}/TNAs

  2. Optical properties of titanium dioxide nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Abdelmoula, Mohamed [Department of Physics, Northeastern University, Boston, Massachusetts 02115 (United States); Department of Materials Science, Carnegie Mellon University, Pittsburgh, PA 15213 (United States); Sokoloff, Jeffrey; Lu, Wen-Tao; Menon, Latika [Department of Physics, Northeastern University, Boston, Massachusetts 02115 (United States); Close, Thomas; Richter, Christiaan, E-mail: christiaan.richter@rit.edu [Department of Chemical Engineering, Rochester Institute of Technology, Rochester, New York, 14623 (United States)

    2014-01-07

    We present experimental measurements and a theoretical analysis of the near UV to NIR optical properties of free standing titania nanotube arrays. An improved understanding of the optical physics of this type of nanostructure is important to several next generation solar energy conversion technologies. We measured the transmission, reflection, and absorption of the electromagnetic spectrum from 300 nm to 1000 nm (UV to NIR) of titania nanotube arrays. We measured the total, specular, and diffuse reflection and transmission using both single point detection and an integrating sphere spectrometer. We find that the transmission, but not the reflection, of light (UV to NIR) through the nanotube array is well-explained by classic geometric optics using an effective medium model taking into account the conical geometry of the nanotubes. For wavelengths shorter than ∼500 nm, we find the surprising result that the reflection coefficient for light incident on the open side of the nanotube array is greater than the reflection coefficient for light incident on the closed “floor” of the nanotube array. We consider theoretical models based on the eikonal approximation, photonic crystal band theory, and a statistical treatment of scattering to explain the observed data. We attribute the fact that light with wavelengths shorter than 500 nm is more highly reflected from the open than the closed tube side as being due to disorder scattering inside the nanotube array.

  3. Ordered metal nanotube arrays fabricated by PVD.

    Science.gov (United States)

    Marquez, F; Morant, C; Campo, T; Sanz, J M; Elizalde, E

    2010-02-01

    In this work we report a simple method to fabricate ordered arrays of metal nanotubes. This method is based on the deposition of a metal by PVD onto an anodized aluminum oxide (AAO) template. The dimensions of the synthesized nanotubes depend both on the AAO template and on the deposited metal. In fact, it is observed that the aspect ratios of the nanotubes clearly depend significantly on the metal, ranging from 0.6 (Fe) to at least 3 (Zr).

  4. Functionalized polypyrrole nanotube arrays as electrochemical biosensor for the determination of copper ions

    International Nuclear Information System (INIS)

    Lin Meng; Hu Xiaoke; Ma Zhaohu; Chen Lingxin

    2012-01-01

    Highlights: ► PPy nanotube arrays were electropolymerized using ZnO nanowire arrays as templates. ► PPy nanotube arrays were anchored onto ITO glass without any chemical linker. ► Using SWV, the biosensor was found to be highly sensitive and selective to Cu 2+ . ► The biosensor was successfully applied for the determination of Cu 2+ in drinking water. - Abstract: A novel electrochemical biosensor based on functionalized polypyrrole (PPy) nanotube arrays modified with a tripeptide (Gly-Gly-His) proved to be highly effective for electrochemical analysis of copper ions (Cu 2+ ). The vertically oriented PPy nanotube arrays were electropolymerized by using modified zinc oxide (ZnO) nanowire arrays as templates which were electrodeposited on indium–tin oxide (ITO) coated glass substrates. The electrodes were functionalized by appending pyrrole-α-carboxylic acid onto the surface of polypyrrole nanotube arrays by electrochemical polymerization. The carboxylic groups of the polymer were covalently coupled with the amine groups of the tripeptide, and its structural features were confirmed by attenuated total reflection infrared (ATR-IR) spectroscopy. The tripeptide modified PPy nanotube arrays electrode was used for the electrochemical analysis of various trace copper ions by square wave voltammetry. The electrode was found to be highly sensitive and selective to Cu 2+ in the range of 0.1–30 μM. Furthermore, the developed biosensor exhibited a high stability and reproducibility, despite the repeated use of the biosensor electrode.

  5. Microneedle array electrode for human EEG recording.

    NARCIS (Netherlands)

    Lüttge, Regina; van Nieuwkasteele-Bystrova, Svetlana Nikolajevna; van Putten, Michel Johannes Antonius Maria; Vander Sloten, Jos; Verdonck, Pascal; Nyssen, Marc; Haueisen, Jens

    2009-01-01

    Microneedle array electrodes for EEG significantly reduce the mounting time, particularly by circumvention of the need for skin preparation by scrubbing. We designed a new replication process for numerous types of microneedle arrays. Here, polymer microneedle array electrodes with 64 microneedles,

  6. Virtual electrodes for high-density electrode arrays

    Science.gov (United States)

    Cela, Carlos J.; Lazzi, Gianluca

    2015-10-13

    The present embodiments are directed to implantable electrode arrays having virtual electrodes. The virtual electrodes may improve the resolution of the implantable electrode array without the burden of corresponding complexity of electronic circuitry and wiring. In a particular embodiment, a virtual electrode may include one or more passive elements to help steer current to a specific location between the active electrodes. For example, a passive element may be a metalized layer on a substrate that is adjacent to, but not directly connected to an active electrode. In certain embodiments, an active electrode may be directly coupled to a power source via a conductive connection. Beneficially, the passive elements may help to increase the overall resolution of the implantable array by providing additional stimulation points without requiring additional wiring or driver circuitry for the passive elements.

  7. Force sensitive carbon nanotube arrays for biologically inspired airflow sensing

    Science.gov (United States)

    Maschmann, Matthew R.; Dickinson, Ben; Ehlert, Gregory J.; Baur, Jeffery W.

    2012-09-01

    The compressive electromechanical response of aligned carbon nanotube (CNT) arrays is evaluated for use as an artificial hair sensor (AHS) transduction element. CNT arrays with heights of 12, 75, and 225 µm are examined. The quasi-static and dynamic sensitivity to force, response time, and signal drift are examined within the range of applied stresses predicted by a mechanical model applicable to the conceptual CNT array-based AHS (0-1 kPa). Each array is highly sensitive to compressive loading, with a maximum observed gauge factor of 114. The arrays demonstrate a repeatable response to dynamic cycling after a break-in period of approximately 50 cycles. Utilizing a four-wire measurement electrode configuration, the change in contact resistance between the array and the electrodes is observed to dominate the electromechanical response of the arrays. The response time of the CNT arrays is of the order of 10 ms. When the arrays are subjected to constant stress, mechanical creep is observed that results in a signal drift that generally diminishes the responsiveness of the arrays, particularly at stress approaching 1 kPa. The results of this study serve as a preliminary proof of concept for utilizing CNT arrays as a transduction mechanism for a proposed artificial hair sensor. Such a low profile and light-weight flow sensor is expected to have application in a number of applications including navigation and state awareness of small air vehicles, similar in function to natural hair cell receptors utilized by insects and bats.

  8. Fabrication of titanium dioxide nanotube arrays using organic electrolytes

    Science.gov (United States)

    Yoriya, Sorachon

    anodization rates are relatively slower in DEG electrolyte; as a result, the nanotube length is typically less than 10 microm. Pore size of nanotubes grown in DEG has been extended from 150 nm up to approximately 400 nm. The approach to pore widening could be achieved by using a specific condition of low HF concentration and prolonged anodization time. The study of evolution of nanotubes grown in DEG electrolytes showed that a fibrous layer was formed in the early growth stages and then was chemically and gradually removed after a long duration, leaving behind the nanotubes with large pore size. In DEG electrolyte, the closer spacing between Ti and Pt electrodes resulted in the larger nanotube morphological parameters due to the enhanced electrode kinetics facilitating the electrode reactions. Furthermore, this dissertation showed possibilities to crystallize the titania nanotube array films at room temperature via anodization in either DMSO or DEG electrolytes. The partially crystallized films could be achieved specifically in the optimum slow growth process conditions. Due to partial crystallization of the as-anodized samples, the high temperature annealing study revealed that the temperatures of phase transformation are 260 ºC and 430°C for respectively amorphous to anatase and anatase to rutile, which are accounted as the lowest phase transformation temperatures reported to date (2010). Finally, the photoelectrochemical properties of the DMSO fabricated nanotubes were investigated. The maximum photocurrent density of ~ 11 mA cm--2 was achieved by using the 46-microm long nanotube array sample with completely open pores, and photoconversion efficiencies of 5.425 % (+/- 0.087) (under UV light) and 0.197 % (+/- 0.001) (under solar spectrum AM 1.5) have been demonstrated. Biomedical applications of the DEG fabricated nanotube arrays films such as blood clotting, hemocompatibility, and drug delivery were investigated. The titania nanotube arrays showed a significant platelet

  9. Fabrication and characterization of CaP-coated nanotube arrays

    International Nuclear Information System (INIS)

    Kung, Kuan-Chen; Chen, Jia-Ling; Liu, Yen-Ting; Lee, Tzer-Min

    2015-01-01

    Modified anodization techniques have been shown to improve the biocompatibility of titanium. This study demonstrated the anodic formation of self-organized nanotube arrays on titanium from an electrolyte solution containing 1 M H 3 PO 4 and 1 wt% hydrofluoric acid (HF). Our aim was to investigate the effects of sputter-deposited CaP on nanotube arrays. SEM images revealed a surface with uniform morphology and an average pore diameter of 29 nm. XRD results indicated that the phase of the nanotube arrays was amorphous. Electron spectroscopy for chemical analysis (ESCA) confirmed that the nanotube arrays were coated with calcium and phosphorus. Cell culture experiments using human osteosarcoma (HOS) cells demonstrated that the CaP/nanotube arrays had a pronounced effect on initial cell attachment as well as on the number of cells at 1, 7, and 14 days. Compared to as-polished titanium, the CaP/nanotube arrays accelerated cell proliferation, attachment, and spreading. Our results demonstrate the pronounced effects of CaP/nanotube arrays on the biological responses of HOS cells. - Highlights: • Self-organized nanotube arrays were anodically formed on titanium. • Surfaces of nanotube arrays exhibited uniform morphology and pore size. • According to ESCA results, Ca and P were successfully coated on nanotube arrays. • CaP/nanotube arrays accelerated the attachment and spreading of cells. • CaP/nanotube arrays were shown to affect biological responses of cells

  10. Fabrication and characterization of CaP-coated nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Kung, Kuan-Chen; Chen, Jia-Ling [Institute of Oral Medicine, National Cheng Kung University, Tainan 701, Taiwan (China); Liu, Yen-Ting [Department of Materials Science and Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Lee, Tzer-Min, E-mail: tmlee@mail.ncku.edu.tw [Institute of Oral Medicine, National Cheng Kung University, Tainan 701, Taiwan (China); Medical Device Innovation Center, National Cheng Kung University, Tainan 701, Taiwan (China); School of Dentistry, Kaohsiung Medical University, Kaohsiung 807, Taiwan (China)

    2015-03-01

    Modified anodization techniques have been shown to improve the biocompatibility of titanium. This study demonstrated the anodic formation of self-organized nanotube arrays on titanium from an electrolyte solution containing 1 M H{sub 3}PO{sub 4} and 1 wt% hydrofluoric acid (HF). Our aim was to investigate the effects of sputter-deposited CaP on nanotube arrays. SEM images revealed a surface with uniform morphology and an average pore diameter of 29 nm. XRD results indicated that the phase of the nanotube arrays was amorphous. Electron spectroscopy for chemical analysis (ESCA) confirmed that the nanotube arrays were coated with calcium and phosphorus. Cell culture experiments using human osteosarcoma (HOS) cells demonstrated that the CaP/nanotube arrays had a pronounced effect on initial cell attachment as well as on the number of cells at 1, 7, and 14 days. Compared to as-polished titanium, the CaP/nanotube arrays accelerated cell proliferation, attachment, and spreading. Our results demonstrate the pronounced effects of CaP/nanotube arrays on the biological responses of HOS cells. - Highlights: • Self-organized nanotube arrays were anodically formed on titanium. • Surfaces of nanotube arrays exhibited uniform morphology and pore size. • According to ESCA results, Ca and P were successfully coated on nanotube arrays. • CaP/nanotube arrays accelerated the attachment and spreading of cells. • CaP/nanotube arrays were shown to affect biological responses of cells.

  11. DNA-FET using carbon nanotube electrodes

    International Nuclear Information System (INIS)

    Sasaki, T K; Ikegami, A; Aoki, N; Ochiai, Y

    2006-01-01

    We demonstrate DNA field effect transistor (DNA-FET) using multiwalled carbon nanotube (MWNT) as nano-structural source and drain electrodes. The MWNT electrodes have been fabricated by focused ion-beam bombardment (FIBB). A very short channel, approximately 50 nm, was easily formed between the severed MWNT. The current-voltage (I-V) characteristics of DNA molecules between the MWNT electrodes showed hopping transport property. We have also measured the gate-voltage dependence in the I-V characteristics and found that poly DNA molecules exhibits p-type conduction. The transport of DNA-FET can be explained by two hopping lengths which depend on the range of the source-drain bias voltages

  12. High-performance flexible supercapacitor based on porous array electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Shieh, Jen-Yu; Tsai, Sung-Ying; Li, Bo-Yan [Institute of Electro-Optical and Materials Science, National Formosa University, 64 Wenhua Road, Huwei, Yunlin 63208, Taiwan (China); Yu, Hsin Her, E-mail: hhyu@nfu.edu.tw [Department of Biotechnology, National Formosa University, 64 Wenhua Road, Huwei, Yunlin 63208, Taiwan (China)

    2017-07-01

    In this study, an array of polystyrene (PS) spheres was synthesized by a dispersion-polymerization technique as a template onto which a porous polydimethylsiloxane (PDMS) microarray structure was fabricated by soft lithography. A conducting layer was coated on the surface of the microarray after a suspension of multi-walled carbon nanotubes (MWCNTs) mixed with graphene (G) had been poured into the porous array. A PDMS-based porous supercapacitor was assembled by sandwiching a separator between two porous electrodes filled with a H{sub 3}PO{sub 4}/polyvinyl alcohol (PVA) gel electrolyte. The specific capacitance, electrochemical properties, and cycle stability of the porous electrode supercapacitors were explored. The porous PDMS-electrode-based supercapacitor exhibited high specific capacitance and good cycle stability, indicating its enormous potential for future applications in wearable and portable electronic products. - Highlights: • Porous electrode was prepared using an array of polystyrene spheres as template. • The porous electrodes provided increased contact area with the electrolyte. • A gel electrolyte averted problems with leakage and poor interfacial contact. • A larger separator pore size effectively reduced the internal resistance, iR{sub drop}. • Porous PDMS supercapacitor showed superior flexibility and cycling stability.

  13. A novel method for the fabrication of a high-density carbon nanotube microelectrode array

    Directory of Open Access Journals (Sweden)

    Adam Khalifa

    2015-09-01

    Full Text Available We present a novel method for fabricating a high-density carbon nanotube microelectrode array (MEA chip. Vertically aligned carbon nanotubes (VACNTs were synthesized by microwave plasma-enhanced chemical vapor deposition and thermal chemical vapor deposition. The device was characterized using electrochemical experiments such as cyclic voltammetry, impedance spectroscopy and potential transient measurements. Through-silicon vias (TSVs were fabricated and partially filled with polycrystalline silicon to allow electrical connection from the high-density electrodes to a stimulator microchip. In response to the demand for higher resolution implants, we have developed a unique process to obtain a high-density electrode array by making the microelectrodes smaller in size and designing new ways of routing the electrodes to current sources. Keywords: Microelectrode array, Neural implant, Carbon nanotubes, Through-silicon via interconnects, Microfabrication

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

    International Nuclear Information System (INIS)

    Rosario-Castro, Belinda I.; Contes-de-Jesus, Enid J.; Lebron-Colon, Marisabel; Meador, Michael A.; Scibioh, M. Aulice; Cabrera, Carlos R.

    2010-01-01

    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.

  15. Force sensitive carbon nanotube arrays for biologically inspired airflow sensing

    International Nuclear Information System (INIS)

    Maschmann, Matthew R; Ehlert, Gregory J; Baur, Jeffery W; Dickinson, Ben

    2012-01-01

    The compressive electromechanical response of aligned carbon nanotube (CNT) arrays is evaluated for use as an artificial hair sensor (AHS) transduction element. CNT arrays with heights of 12, 75, and 225 µm are examined. The quasi-static and dynamic sensitivity to force, response time, and signal drift are examined within the range of applied stresses predicted by a mechanical model applicable to the conceptual CNT array-based AHS (0–1 kPa). Each array is highly sensitive to compressive loading, with a maximum observed gauge factor of 114. The arrays demonstrate a repeatable response to dynamic cycling after a break-in period of approximately 50 cycles. Utilizing a four-wire measurement electrode configuration, the change in contact resistance between the array and the electrodes is observed to dominate the electromechanical response of the arrays. The response time of the CNT arrays is of the order of 10 ms. When the arrays are subjected to constant stress, mechanical creep is observed that results in a signal drift that generally diminishes the responsiveness of the arrays, particularly at stress approaching 1 kPa. The results of this study serve as a preliminary proof of concept for utilizing CNT arrays as a transduction mechanism for a proposed artificial hair sensor. Such a low profile and light-weight flow sensor is expected to have application in a number of applications including navigation and state awareness of small air vehicles, similar in function to natural hair cell receptors utilized by insects and bats. (paper)

  16. Amorphous and crystalline TiO2 nanotube arrays for enhanced Li-ion intercalation properties.

    Science.gov (United States)

    Guan, Dongsheng; Cai, Chuan; Wang, Ying

    2011-04-01

    We have employed a simple process of anodizing Ti foils to prepare TiO2 nanotube arrays which show enhanced electrochemical properties for applications as Li-ion battery electrode materials. The lengths and pore diameters of TiO2 nanotubes can be finely tuned by varying voltage, electrolyte composition, or anodization time. The as-prepared nanotubes are amorphous and can be converted into anatase nanotubes with heat treatment at 480 degrees C. Rutile crystallites emerge in the anatase nanotube when the annealing temperature is increased to 580 degrees C, resulting in TiO2 nanotubes of mixed phases. The morphological features of nanotubes remain unchanged after annealing. Li-ion insertion performance has been studied for amorphous and crystalline TiO2 nanotube arrays. Amorphous nanotubes with a length of 3.0 microm and an outer diameter of 125 nm deliver a capacity of 91.2 microA h cm(-2) at a current density of 400 microA cm(-2), while those with a length of 25 microm and an outer diameter of 158 nm display a capacity of 533 microA h cm-2. When the 3-microm long nanotubes become crystalline, they deliver lower capacities: the anatase nanotubes and nanotubes of mixed phases show capacities of 53.8 microA h cm-2 and 63.1 microA h cm(-2), respectively at the same current density. The amorphous nanotubes show excellent capacity retention ability over 50 cycles. The cycled nanotubes show little change in morphology compared to the nanotubes before electrochemical cycling. All the TiO2 nanotubes demonstrate higher capacities than amorphous TiO2 compact layer reported in literature. The amorphous TiO2 nanotubes with a length of 1.9 microm exhibit a capacity five times higher than that of TiO2 compact layer even when the nanotube array is cycled at a current density 80 times higher than that for the compact layer. These results suggest that anodic TiO2 nanotube arrays are promising electrode materials for rechargeable Li-ion batteries.

  17. Investigation on the Photoelectrocatalytic Activity of Well-Aligned TiO2 Nanotube Arrays

    Directory of Open Access Journals (Sweden)

    Xiaomeng Wu

    2012-01-01

    Full Text Available Well-aligned TiO2 nanotube arrays were fabricated by anodizing Ti foil in viscous F− containing organic electrolytes, and the crystal structure and morphology of the TiO2 nanotube array were characterized and analyzed by XRD, SEM, and TEM, respectively. The photocatalytic activity of the TiO2 nanotube arrays was evaluated in the photocatalytic (PC and photoelectrocatalytic (PEC degradation of methylene blue (MB dye in different supporting solutions. The excellent performance of ca. 97% for color removal was reached after 90 min in the PEC process compared to that of PC process which indicates that a certain external potential bias favors the promotion of the electrode reaction rate on TiO2 nanotube array when it is under illumination. In addition, it is found that PEC process conducted in supporting solutions with low pH and containing Cl− is also beneficial to accelerate the degradation rate of MB.

  18. Template-based fabrication of nanowire-nanotube hybrid arrays

    International Nuclear Information System (INIS)

    Ye Zuxin; Liu Haidong; Schultz, Isabel; Wu Wenhao; Naugle, D G; Lyuksyutov, I

    2008-01-01

    The fabrication and structure characterization of ordered nanowire-nanotube hybrid arrays embedded in porous anodic aluminum oxide (AAO) membranes are reported. Arrays of TiO 2 nanotubes were first deposited into the pores of AAO membranes by a sol-gel technique. Co nanowires were then electrochemically deposited into the TiO 2 nanotubes to form the nanowire-nanotube hybrid arrays. Scanning electron microscopy and transmission electron microscopy measurements showed a high nanowire filling factor and a clean interface between the Co nanowire and the TiO 2 nanotube. Application of these hybrids to the fabrication of ordered nanowire arrays with highly controllable geometric parameters is discussed

  19. Fabrication of Vertically Aligned Carbon Nanotube or Zinc Oxide Nanorod Arrays for Optical Diffraction Gratings.

    Science.gov (United States)

    Kim, Jeong; Kim, Sun Il; Cho, Seong-Ho; Hwang, Sungwoo; Lee, Young Hee; Hur, Jaehyun

    2015-11-01

    We report on new fabrication methods for a transparent, hierarchical, and patterned electrode comprised of either carbon nanotubes or zinc oxide nanorods. Vertically aligned carbon nanotubes or zinc oxide nanorod arrays were fabricated by either chemical vapor deposition or hydrothermal growth, in combination with photolithography. A transparent conductive graphene layer or zinc oxide seed layer was employed as the transparent electrode. On the patterned surface defined using photoresist, the vertically grown carbon nanotubes or zinc oxides could produce a concentrated electric field under applied DC voltage. This periodic electric field was used to align liquid crystal molecules in localized areas within the optical cell, effectively modulating the refractive index. Depending on the material and morphology of these patterned electrodes, the diffraction efficiency presented different behavior. From this study, we established the relationship between the hierarchical structure of the different electrodes and their efficiency for modulating the refractive index. We believe that this study will pave a new path for future optoelectronic applications.

  20. High power and high energy electrodes using carbon nanotubes

    Science.gov (United States)

    Martini, Fabrizio; Brambilla, Nicolo Michele; Signorelli, Riccardo

    2015-04-07

    An electrode useful in an energy storage system, such as a capacitor, includes an electrode that includes at least one to a plurality of layers of compressed carbon nanotube aggregate. Methods of fabrication are provided. The resulting electrode exhibits superior electrical performance in terms of gravimetric and volumetric power density.

  1. Novel iron oxide nanotube arrays as high-performance anodes for lithium ion batteries

    Science.gov (United States)

    Zhong, Yuan; Fan, Huiqing; Chang, Ling; Shao, Haibo; Wang, Jianming; Zhang, Jianqing; Cao, Chu-nan

    2015-11-01

    Nanostructured iron oxides can be promising anode materials for lithium ion batteries (LIBs). However, improvement on the rate capability and/or electrochemical cycling stability of iron oxide anode materials remains a key challenge because of their poor electrical conductivities and large volume expansion during cycling. Herein, the vertically aligned arrays of one-dimensional (1D) iron oxide nanotubes with 5.8 wt% carbon have been fabricated by a novel surfactant-free self-corrosion process and subsequent thermal treatment. The as-fabricated nanotube array electrode delivers a reversible capacity of 932 mAh g-1 after 50 charge-discharge cycles at a current of 0.6 A g-1. The electrode still shows a reversible capacity of 610 mAh g-1 even at a very high rate (8.0 A g-1), demonstrating its prominent rate capability. Furthermore, the nanotube array electrode also exhibits the excellent electrochemical cycling stability with a reversible capacity of 880 mAh g-1 after 500 cycles at a current of 4 A g-1. The nanotube array electrode with superior lithium storage performance reveals the promising potential as a high-performance anode for LIBs.

  2. 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.

  3. Carbon Nanofiber Electrode Array for Neurochemical Monitoring

    Science.gov (United States)

    Koehne, Jessica E.

    2017-01-01

    A sensor platform based on vertically aligned carbon nanofibers (CNFs) has been developed. Their inherent nanometer scale, high conductivity, wide potential window, good biocompatibility and well-defined surface chemistry make them ideal candidates as biosensor electrodes. Here, we report using vertically aligned CNF as neurotransmitter recording electrodes for application in a smart deep brain stimulation (DBS) device. Our approach combines a multiplexed CNF electrode chip, developed at NASA Ames Research Center, with the Wireless Instantaneous Neurotransmitter Concentration Sensor (WINCS) system, developed at the Mayo Clinic. Preliminary results indicate that the CNF nanoelectrode arrays are easily integrated with WINCS for neurotransmitter detection in a multiplexed array format. In the future, combining CNF based stimulating and recording electrodes with WINCS may lay the foundation for an implantable smart therapeutic system that utilizes neurochemical feedback control while likely resulting in increased DBS application in various neuropsychiatric disorders. In total, our goal is to take advantage of the nanostructure of CNF arrays for biosensing studies requiring ultrahigh sensitivity, high-degree of miniaturization, and selective biofunctionalization.

  4. Improved electrochemical performances of CuO nanotube array prepared via electrodeposition as anode for lithium ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Anguo, E-mail: hixiaoanguo@126.com; Zhou, Shibiao; Zuo, Chenggang; Zhuan, Yongbing; Ding, Xiang

    2015-10-15

    Graphical abstract: CuO nanotube array electrodes prepared by electrodeposition method exhibit an excellent lithium ion storage ability as anode of Li-ion battery. - Highlights: • CuO nanotube arrays are synthesized by an electrodeposition method. • CuO nanotube shows a high-rate performance. • CuO nanotube shows an excellent cycling performance. - Abstract: We report a facile strategy to prepared CuO nanotube arrays directly grown on Cu plate through the electrodeposition method. The as-prepared CuO nanotubes show a quasi-cylinder nanostructure with internal diameters of ca. ∼100 nm, external diameters of ca. ∼120 nm, and average length of ∼3 μm. As an anode for lithium ion batteries, the electrochemical properties of the CuO nanotube arrays are investigated by cyclic voltammetry (CV) and galvanostatic charge/discharge tests. Due to the unique nanotube nanostructure, the as-prepared CuO electrodes exhibit good rate performance (550 mAh g{sup −1} at 0.1 C and 464 mAh g{sup −1} at 1 C) and cycling performance (581 mAh g{sup −1} at 0.1 C and 538 mAh g{sup −1} at 0.5 C)

  5. 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.

  6. Electrochemical properties of double wall carbon nanotube electrodes

    OpenAIRE

    Pumera, Martin

    2007-01-01

    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 funct...

  7. Fabrication of high thermal conductivity arrays of carbon nanotubes and their composites

    Science.gov (United States)

    Geohegan, David B [Knoxville, TN; Ivanov, Ilya N [Knoxville, TN; Puretzky, Alexander A [Knoxville, TN

    2010-07-27

    Methods and apparatus are described for fabrication of high thermal conductivity arrays of carbon nanotubes and their composites. A composition includes a vertically aligned nanotube array including a plurality of nanotubes characterized by a property across substantially all of the vertically aligned nanotube array. A method includes depositing a vertically aligned nanotube array that includes a plurality of nanotubes; and controlling a deposition rate of the vertically aligned nanotubes array as a function of an in situ monitored property of the plurality of nanotubes.

  8. Layered growth of aligned carbon nanotube arrays by pyrolysis

    International Nuclear Information System (INIS)

    Zhang Hongrui; Liang Erjun; Ding Pei; Chao Mingju

    2003-01-01

    Based on the study of reaction temperature and duration of the growth of aligned carbon nanotube arrays, layered aligned multi-wall carbon nanotube (MWNT) films grown directly around a reaction quartz tube in an Ar/H 2 atmosphere by pyrolysis of ferrocene in xylene in a suitable reaction furnace with the help of cobalt powder. The scanning electron microscope and transmission electron microscope images indicated that the obtained arrays were composed of many separated layers with MWNTs. The reaction temperature significantly influenced the alignment of the MWNTs, and an appropriate reaction temperature range for growth was 800-900 deg. C. The diameter of the carbon nanotube increased from 46 to 75 nm with the growth temperature. Besides temperature, the reaction duration influenced the length of the well-aligned carbon nanotubes. There was no significant relation between the growth time and the diameter of the carbon nanotubes in the array

  9. Improving Single-Carbon-Nanotube-Electrode Contacts Using Molecular Electronics.

    Science.gov (United States)

    Krittayavathananon, Atiweena; Ngamchuea, Kamonwad; Li, Xiuting; Batchelor-McAuley, Christopher; Kätelhön, Enno; Chaisiwamongkhol, Korbua; Sawangphruk, Montree; Compton, Richard G

    2017-08-17

    We report the use of an electroactive species, acetaminophen, to modify the electrical connection between a carbon nanotube (CNT) and an electrode. By applying a potential across two electrodes, some of the CNTs in solution occasionally contact the electrified interface and bridge between two electrodes. By observing a single CNT contact between two microbands of an interdigitated Au electrode in the presence and absence of acetaminophen, the role of the molecular species at the electronic junction is revealed. As compared with the pure CNT, the current magnitude of the acetaminophen-modified CNTs significantly increases with the applied potentials, indicating that the molecule species improves the junction properties probably via redox shuttling.

  10. Enhancing the electrochemical response of myoglobin with carbon nanotube electrodes.

    Science.gov (United States)

    Esplandiu, M J; Pacios, M; Cyganek, L; Bartroli, J; del Valle, M

    2009-09-02

    In this paper, the electrochemical behavior of different myoglobin-modified carbon electrodes is evaluated. In particular, the performance of voltammetric biosensors made of forest-like carbon nanotubes, carbon nanotube composites and graphite composites is compared by monitoring mainly the electrocatalytic reduction of H(2)O(2) by myoglobin and their corresponding electroanalytical characteristics. Graphite composites showed the worst electroanalytical performance, exhibiting a small linear range, a limit of detection (LOD) of 9 x 10(-5) M and low sensitivity. However, it was found that the electrochemical response was enhanced with the use of carbon nanotube-based electrodes with LOD up to 5 x 10(-8) M, higher sensitivities and wider linear range response. On the one hand, in the case of the CNT epoxy composite, the improvement in the response can be mainly attributed to its more porous surface which allows the immobilization of higher amounts of the electroactive protein. On the other hand, in the case of the forest-like CNT electrodes, the enhancement is due to an increase in the electron transfer kinetics. These findings encourage the use of myoglobin-modified carbon nanotube electrodes as potential (bio)sensors of H(2)O(2) or O(2) in biology, microbiology and environmental fields.

  11. Carbon nanotube yarns as strong flexible conductive capacitive electrodes

    NARCIS (Netherlands)

    Liu, F.; Wagterveld, R.M.; Gebben, B.; Otto, M.J.; Biesheuvel, P.M.; Hamelers, H.V.M.

    2015-01-01

    Carbon nanotube (CNT) yarn, consisting of 23 µm diameter CNT filaments, can be used as capacitive electrodes that are long, flexible, conductive and strong, for applications in energy and electrochemical water treatment. We measure the charge storage capacity as function of salt concentration, and

  12. Carbon paste electrode incorporating multi-walled carbon nanotube ...

    Indian Academy of Sciences (India)

    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 ...

  13. 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

  14. Developing barbed microtip-based electrode arrays for biopotential measurement.

    Science.gov (United States)

    Hsu, Li-Sheng; Tung, Shu-Wei; Kuo, Che-Hsi; Yang, Yao-Joe

    2014-07-10

    This study involved fabricating barbed microtip-based electrode arrays by using silicon wet etching. KOH anisotropic wet etching was employed to form a standard pyramidal microtip array and HF/HNO3 isotropic etching was used to fabricate barbs on these microtips. To improve the electrical conductance between the tip array on the front side of the wafer and the electrical contact on the back side, a through-silicon via was created during the wet etching process. The experimental results show that the forces required to detach the barbed microtip arrays from human skin, a polydimethylsiloxane (PDMS) polymer, and a polyvinylchloride (PVC) film were larger compared with those required to detach microtip arrays that lacked barbs. The impedances of the skin-electrode interface were measured and the performance levels of the proposed dry electrode were characterized. Electrode prototypes that employed the proposed tip arrays were implemented. Electroencephalogram (EEG) and electrocardiography (ECG) recordings using these electrode prototypes were also demonstrated.

  15. Structure and dye-sensitized solar cell application of TiO{sub 2} nanotube arrays fabricated by the anodic oxidation method

    Energy Technology Data Exchange (ETDEWEB)

    Ok, Seon-Yeong; Cho, Kwon-Koo; Kim, Ki-Won [School of Material Science and Engineering, ERI and i-cube center, Gyeongsang National University, 900 Gazwadong, Jinju, Gyeongnam 660-701 (Korea, Republic of); Ryu, Kwang-Sun, E-mail: kkcho66@gnu.ac.k [Department of Chemistry, University of Ulsan, Ulsan, 680-749 (Korea, Republic of)

    2010-05-01

    Well-ordered TiO{sub 2} nanotube arrays were fabricated by the potentiostatic anodic oxidation method using pure Ti foil as a working electrode and ethylene glycol solution as an electrolyte with the small addition of NH{sub 4}F and H{sub 2}O. The influence of anodization temperature and time on the morphology and formation of TiO{sub 2} nanotube arrays was examined. The TiO{sub 2} nanotube arrays were applied as a photoelectrode to dye-sensitized solar cells. Regardless of anodizing temperature and time, the average diameter and wall thickness of TiO{sub 2} nanotube arrays show a similar value, whereas the length increases with decreasing reaction temperature. The conversion efficiency is very low, which is due to a morphology breaking of the TiO{sub 2} nanotube arrays in the manufacturing process of a photoelectrode.

  16. Structure and dye-sensitized solar cell application of TiO2 nanotube arrays fabricated by the anodic oxidation method

    Science.gov (United States)

    Ok, Seon-Yeong; Cho, Kwon-Koo; Kim, Ki-Won; Ryu, Kwang-Sun

    2010-05-01

    Well-ordered TiO2 nanotube arrays were fabricated by the potentiostatic anodic oxidation method using pure Ti foil as a working electrode and ethylene glycol solution as an electrolyte with the small addition of NH4F and H2O. The influence of anodization temperature and time on the morphology and formation of TiO2 nanotube arrays was examined. The TiO2 nanotube arrays were applied as a photoelectrode to dye-sensitized solar cells. Regardless of anodizing temperature and time, the average diameter and wall thickness of TiO2 nanotube arrays show a similar value, whereas the length increases with decreasing reaction temperature. The conversion efficiency is very low, which is due to a morphology breaking of the TiO2 nanotube arrays in the manufacturing process of a photoelectrode.

  17. Microelectrode array fabrication for electrochemical detection with carbon nanotubes

    Science.gov (United States)

    Clark, James

    Understanding how the brain works remains one of the key challenges for scientists. To further this understanding a wide variety of technologies and research methods have been developed. One such technology is conductive electrodes, used to measure the electrical signals elicited from neuronal cells and tissues. These electrodes can be fabricated as a singular electrode or as a multi-electrode array (MEA). This permits bio-electrical measurements from one particular area or simultaneous measurements from multiple areas, respectively. Studying electrical and chemical signals of individual cells in situ requires the use of electrodes with ≤20 µm diameter. However, electrodes of this size generally produce high impedance, perturbing recording of the small signals generated from individual cells. Nanomaterials, such as carbon nanotubes (CNTs), can be deposited to increase the real surface area of these electrodes, producing higher sensitivity measurements. This thesis investigates the potential for using photo-thermal chemical vapour deposition grown CNTs as the electrode material for a de novo fabricated MEA. This device aimed to measure electrochemical signals in the form of dopamine, an important mammalian neurotransmitter, as well as conventional bio-electrical signals that the device is designed for. Realising this aim began with improving CNT aqueous wetting behaviour via oxygen plasma functionalisation. This procedure demonstrated grafting of oxygen functional groups to the CNT structure, and dramatic improvements in aqueous wetting behaviour, with CNTs attached to the device. Subsequently, oxygen plasma functionalised CNT-based MEAs were fabricated and tested, allowing comparisons with a non-functionalised CNT MEA and a state-of-the-art commercial MEA. The functionalised CNT MEA demonstrated an order of magnitude improvement compared to commercial MEAs (2.75 kΩ vs. 25.6 kΩ), at the biologically relevant frequency of 1 kHz. This was followed by measurement

  18. Design of a new electrode array for cochlear implants

    International Nuclear Information System (INIS)

    Kha, H.; Chen, B.

    2010-01-01

    Full text: This study aims to design a new electrode array which can be precisely located beneath the basilar membrane within the cochlear scala tympani. This placement of the electrode array is beneficial for increasing the effectiveness of the electrical stimulation of the audi tory nerves and maximising the growth factors delivered into the cochlea for regenerating the progressively lost auditory neurons, thereby significantly improving performance of the cochlear implant systems. Methods The design process involved two steps. First, the biocom patible nitinol-based shape memory alloy, of which mechanical deformation can be controlled using electrical cUTents/fields act vated by body temperature, was selected. Second, five different designs of the electrode array with embedded nitinol actuators were studied (Table I). The finite element method was employed to predict final positions of these electrode arrays. Results The electrode array with three 6 mm actuators at 2-8, 8-J4 and 14-20 mm from the tip (Fig. I) was found to be located most closely to the basilar membrane, compared with those in the other four cases. Conclusions A new nitinol cochlear implant electrode array with three embedded nitinol actuators has been designed. This electrode array is expected to be located beneath the basilar membrane for maximising the delivery of growth factors. Future research will involve the manufacturing of a prototype of this electrode array for use in insertion experiments and neurotrophin release tests.

  19. Activity patterns of cultured neural networks on micro electrode arrays

    NARCIS (Netherlands)

    Rutten, Wim; van Pelt, J.

    2001-01-01

    A hybrid neuro-electronic interface is a cell-cultured micro electrode array, acting as a neural information transducer for stimulation and/or recording of neural activity in the brain or the spinal cord (ventral motor region or dorsal sensory region). It consists of an array of micro electrodes on

  20. Flexible supercapacitor yarns with coaxial carbon nanotube network electrodes

    International Nuclear Information System (INIS)

    Smithyman, Jesse; Liang, Richard

    2014-01-01

    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

  1. Percolation effects in supercapacitors with thin, transparent carbon nanotube electrodes.

    Science.gov (United States)

    King, Paul J; Higgins, Thomas M; De, Sukanta; Nicoloso, Norbert; Coleman, Jonathan N

    2012-02-28

    We have explored the effects of percolation on the properties of supercapacitors with thin nanotube networks as electrodes. We find the equivalent series resistance, R(ESR), and volumetric capacitance, C(V), to be thickness independent for relatively thick electrodes. However, once the electrode thickness falls below a threshold thickness (∼100 nm for R(ESR) and ∼20 nm for C(V)), the properties of the electrode become thickness dependent. We show the thickness dependence of both R(ESR) and C(V) to be consistent with percolation theory. While this is expected for R(ESR), that the capacitance follows a percolation scaling law is not. This occurs because, for sparse networks, the capacitance is proportional to the fraction of nanotubes connected to the main network. This fraction, in turn, follows a percolation scaling law. This allows us to understand and quantify the limitations on the achievable capacitance for transparent supercapacitors. We find that supercapacitors with thickness independent R(ESR) and C(V) occupy a well-defined region of the Ragone plot. However, supercapacitors whose electrodes are limited by percolation occupy a long tail to lower values of energy and power density. For example, replacing electrodes with transparency of T = 80% with thinner networks displaying T = 97% will result in a 20-fold reduction of both power and energy density.

  2. Growth of ZnO nanotube arrays and nanotube based piezoelectric nanogenerators

    KAUST Repository

    Xi, Yi; Song, Jinhui; Xu, Sheng; Yang, Rusen; Gao, Zhiyuan; Hu, Chenguo; Wang, Zhong Lin

    2009-01-01

    We present a systematic study of the growth of hexagonal ZnO nanotube arrays using a solution chemical method by varying the growth temperature (<100 °C), time and solution concentration. A piezoelectric nanogenerator using the as-grown ZnO nanotube arrays has been demonstrated for the first time. The nanogenerator gives an output voltage up to 35 mV. The detailed profile of the observed electric output is understood based on the calculated piezoelectric potential in the nanotube with consideration of the Schottky contact formed between the metal tip and the nanotube; and the mechanism agrees with that proposed for nanowire based nanogenerator. Our study shows that ZnO nanotubes can also be used for harvesting mechanical energy. © 2009 The Royal Society of Chemistry.

  3. Solar fuel production in a novel polymeric electrolyte membrane photoelectrochemical (PEM-PEC) cell with a web of titania nanotube arrays as photoanode and gaseous reactants

    NARCIS (Netherlands)

    Stoll, T.; Zafeiropoulos, G.; Tsampas, M. N.

    2016-01-01

    A novel photoelectrochemical (PEC) cell design is proposed and investigated for H-2 production with gaseous reactants. The core of the cell is a membrane electrode assembly (MEA) that consists of a TiO2 nanotube arrays photoanode, a Pt/C cathode, a Pt/C reference electrode and a proton conducting

  4. Stretchable Transparent Electrode Arrays for Simultaneous Electrical and Optical Interrogation of Neural Circuits in Vivo.

    Science.gov (United States)

    Zhang, Jing; Liu, Xiaojun; Xu, Wenjing; Luo, Wenhan; Li, Ming; Chu, Fangbing; Xu, Lu; Cao, Anyuan; Guan, Jisong; Tang, Shiming; Duan, Xiaojie

    2018-04-09

    Recent developments of transparent electrode arrays provide a unique capability for simultaneous optical and electrical interrogation of neural circuits in the brain. However, none of these electrode arrays possess the stretchability highly desired for interfacing with mechanically active neural systems, such as the brain under injury, the spinal cord, and the peripheral nervous system (PNS). Here, we report a stretchable transparent electrode array from carbon nanotube (CNT) web-like thin films that retains excellent electrochemical performance and broad-band optical transparency under stretching and is highly durable under cyclic stretching deformation. We show that the CNT electrodes record well-defined neuronal response signals with negligible light-induced artifacts from cortical surfaces under optogenetic stimulation. Simultaneous two-photon calcium imaging through the transparent CNT electrodes from cortical surfaces of GCaMP-expressing mice with epilepsy shows individual activated neurons in brain regions from which the concurrent electrical recording is taken, thus providing complementary cellular information in addition to the high-temporal-resolution electrical recording. Notably, the studies on rats show that the CNT electrodes remain operational during and after brain contusion that involves the rapid deformation of both the electrode array and brain tissue. This enables real-time, continuous electrophysiological monitoring of cortical activity under traumatic brain injury. These results highlight the potential application of the stretchable transparent CNT electrode arrays in combining electrical and optical modalities to study neural circuits, especially under mechanically active conditions, which could potentially provide important new insights into the local circuit dynamics of the spinal cord and PNS as well as the mechanism underlying traumatic injuries of the nervous system.

  5. Dipolar interaction in arrays of magnetic nanotubes

    International Nuclear Information System (INIS)

    Velázquez-Galván, Y; Martínez-Huerta, J M; Encinas, A; De La Torre Medina, J; Danlée, Y; Piraux, L

    2014-01-01

    The dipolar interaction field in arrays of nickel nanotubes has been investigated on the basis of expressions derived from the effective demagnetizing field of the assembly as well as magnetometry measurements. The model incorporates explicitly the wall thickness and aspect ratio, as well as the spatial order of the nanotubes. The model and experiment show that the interaction field in nanotubes is smaller than that in solid nanowires due to the packing fraction reduction in tubes related to their inner cavity. Finally, good agreement between the model and experiment is found for the variation of the interaction field as a function of the tube wall thickness. (paper)

  6. Inherent-opening-controlled pattern formation in carbon nanotube arrays

    International Nuclear Information System (INIS)

    Huang Xiao; Zhou, Jijie J; Sansom, Elijah; Gharib, Morteza; Haur, Sow Chorng

    2007-01-01

    We have introduced inherent openings into densely packed carbon nanotube arrays to study self-organized pattern formation when the arrays undergo a wetting-dewetting treatment from nanotube tips. These inherent openings, made of circular or elongated hollows in nanotube mats, serve as dewetting centres, from where liquid recedes from. As the dewetting centres initiate dry zones and the dry zones expand, surrounding nanotubes are pulled away from the dewetting centres by liquid surface tension. Among short nanotubes, the self-organized patterns are consistent with the shape of the inherent openings, i.e. slender openings lead to elongated trench-like structures, and circular holes result in relatively round nest-like arrangements. Nanotubes in a relatively high mat are more connected, like in an elastic body, than those in a short mat. Small cracks often initialize themselves in a relatively high mat, along two or more adjacent round openings; each of the cracks evolves into a trench as liquid dries up. Self-organized pattern control with inherent openings needs to initiate the dewetting process above the nanotube tips. If there is no liquid on top, inherent openings barely enlarge themselves after the wetting-dewetting treatment

  7. Modiolus-Hugging Intracochlear Electrode Array with Shape Memory Alloy

    Directory of Open Access Journals (Sweden)

    Kyou Sik Min

    2013-01-01

    Full Text Available In the cochlear implant system, the distance between spiral ganglia and the electrodes within the volume of the scala tympani cavity significantly affects the efficiency of the electrical stimulation in terms of the threshold current level and spatial selectivity. Because the spiral ganglia are situated inside the modiolus, the central axis of the cochlea, it is desirable that the electrode array hugs the modiolus to minimize the distance between the electrodes and the ganglia. In the present study, we propose a shape-memory-alloy-(SMA- embedded intracochlear electrode which gives a straight electrode a curved modiolus-hugging shape using the restoration force of the SMA as triggered by resistive heating after insertion into the cochlea. An eight-channel ball-type electrode array is fabricated with an embedded titanium-nickel SMA backbone wire. It is demonstrated that the electrode array changes its shape in a transparent plastic human cochlear model. To verify the safe insertion of the electrode array into the human cochlea, the contact pressures during insertion at the electrode tip and the contact pressures over the electrode length after insertion were calculated using a 3D finite element analysis. The results indicate that the SMA-embedded electrode is functionally and mechanically feasible for clinical applications.

  8. Electrodeposition of polyfluorene on a carbon nanotube electrode

    International Nuclear Information System (INIS)

    Valentini, L; Mengoni, F; Mattiello, L; Kenny, J M

    2007-01-01

    Electrophoretically deposited single-walled carbon nanotube (SWCNT) films on a transparent conducting surface are used as electrodes for the electrodeposition of a π-conjugated polymer formed by the oxidative coupling of fluorene units. This method provides a uniform coverage of the conducting surface with respect to SWCNTs chemically assembled on a gold substrate. Electron microscopy reveals the formation of a polymer-SWCNT nanostructure which imparts distinct electrical properties from those of the polymer electrodeposited on the neat electrode. By combining the attractive properties of SWCNTs and polyfluorene, these nanocomposites open up new opportunities to achieve electrical contacts in nano- to micro-devices

  9. 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.

  10. Flexible electroluminescent device with inkjet-printed carbon nanotube electrodes

    Science.gov (United States)

    Azoubel, Suzanna; Shemesh, Shay; Magdassi, Shlomo

    2012-08-01

    Carbon nanotube (CNTs) inks may provide an effective route for producing flexible electronic devices by digital printing. In this paper we report on the formulation of highly concentrated aqueous CNT inks and demonstrate the fabrication of flexible electroluminescent (EL) devices by inkjet printing combined with wet coating. We also report, for the first time, on the formation of flexible EL devices in which all the electrodes are formed by inkjet printing of low-cost multi-walled carbon nanotubes (MWCNTs). Several flexible EL devices were fabricated by using different materials for the production of back and counter electrodes: ITO/MWCNT and MWCNT/MWCNT. Transparent electrodes were obtained either by coating a thin layer of the CNTs or by inkjet printing a grid which is composed of empty cells surrounded by MWCNTs. It was found that the conductivity and transparency of the electrodes are mainly controlled by the MWCNT film thickness, and that the dominant factor in the luminance intensity is the transparency of the electrode.

  11. Carbon nanotube fiber mats for microbial fuel cell electrodes.

    Science.gov (United States)

    Delord, Brigitte; Neri, Wilfrid; Bertaux, Karen; Derre, Alain; Ly, Isabelle; Mano, Nicolas; Poulin, Philippe

    2017-11-01

    Novel carbon nanotube based electrodes of microbial fuel cells (MFC) have been developed. MFC is a promising technology for the wastewater treatment and the production of electrical energy from redox reactions of natural substrates. Performances of such bio-electrochemical systems depend critically on the structure and properties of the electrodes. The presently developed materials are made by weaving fibers solely comprised of carbon nanotubes. They exhibit a large scale porosity controlled by the weaving process. This porosity allows an easy colonization by electroactive bacteria. In addition, the fibers display a nanostructuration that promotes excellent growth and adhesion of the bacteria at the surface of the electrodes. This unique combination of large scale porosity and nanostructuration allows the present electrodes to perform better than carbon reference. When used as anode in a bioelectrochemical reactor in presence of Geobacter sulfurreducens bacteria, the present electrodes show a maximal current density of about 7.5mA/cm 2 . Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Integrated high-efficiency Pt/carbon nanotube arrays for PEM fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Weimin; Minett, Andrew I.; Zhao, Jie; Razal, Joselito M.; Wallace, Gordon G.; Romeo, Tony; Chen, Jun [Intelligent Polymer Research Institute, AIIM Facility, Innovation Campus, University of Wollongong, NSW 2522 (Australia); Gao, Mei [Division of Materials Science and Engineering, CSIRO, Bayview Ave, Clayton, VIC 3168 (Australia)

    2011-07-15

    A facile strategy to deposit Pt nanoparticles with various metal-loading densities on vertically aligned carbon nanotube (ACNT) arrays as electrocatalysts for proton exchange membrane (PEM) fuel cells is described. The deposition is achieved by electrostatic adsorption of the Pt precursor on the positively charged polyelectrolyte functionalized ACNT arrays and subsequent reduction by L-ascorbic acid. The application of the aligned electrocatalysts in fuel cells is realized by transferring from a quartz substrate to nafion membrane using a hot-press procedure to fabricate the membrane electrode assembly (MEA). It is shown that the MEA with vertically aligned structured electrocatalysts provides better Pt utilization than that with Pt on conventional carbon nanotubes or carbon black, resulting in higher fuel cell performance. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Visible diffraction from quasi-crystalline arrays of carbon nanotubes

    Science.gov (United States)

    Butler, Timothy P.; Butt, Haider; Wilkinson, Timothy D.; Amaratunga, Gehan A. J.

    2015-08-01

    Large area arrays of vertically-aligned carbon nanotubes (VACNTs) are patterned in a quasi-crystalline Penrose tile arrangement through electron beam lithography definition of Ni catalyst dots and subsequent nanotube growth by plasma-enhanced chemical vapour deposition. When illuminated with a 532 nm laser beam high-quality and remarkable diffraction patterns are seen. The diffraction is well matched to theoretical calculations which assume apertures to be present at the location of the VACNTs for transmitted light. The results show that VACNTs act as diffractive elements in reflection and can be used as spatially phased arrays for producing tailored diffraction patterns.

  14. ELECTROCHEMICAL DETERMINATION OF HYDROGEN SULFIDE AT CARBON NANOTUBE MODIFIED ELECTRODES. (R830900)

    Science.gov (United States)

    Carbon nanotube (CNT) modified glassy carbon electrodes exhibiting a strong and stable electrocatalytic response towards sulfide are described. A substantial (400 mV) decrease in the overvoltage of the sulfide oxidation reaction (compared to ordinary carbon electrodes) is...

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

    KAUST Repository

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

    2009-01-01

    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.

  16. 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.

  17. Wearable carbon nanotube based dry-electrodes for electrophysiological sensors

    Science.gov (United States)

    Kang, Byeong-Cheol; Ha, Tae-Jun

    2018-05-01

    In this paper, we demonstrate all-solution-processed carbon nanotube (CNT) dry-electrodes for the detection of electrophysiological signals such as electrocardiograms (ECG) and electromyograms (EMG). The key parameters of P, Q, R, S, and T peaks are successfully extracted by such CNT based dry-electrodes, which is comparable with conventional silver/chloride (Ag/AgCl) wet-electrodes with a conducting gel film for the ECG recording. Furthermore, the sensing performance of CNT based dry-electrodes is secured during the bending test of 200 cycles, which is essential for wearable electrophysiological sensors in a non-invasive method on human skin. We also investigate the application of wearable CNT based dry-electrodes directly attached to the human skins such as forearm for sensing the electrophysiological signals. The accurate and rapid sensing response can be achieved by CNT based dry-electrodes to supervise the health condition affected by excessive physical movements during the real-time measurements.

  18. Electrochemical impedance measurement of a carbon nanotube probe electrode

    International Nuclear Information System (INIS)

    Inaba, Akira; Takei, Yusuke; Kan, Tetsuo; Shimoyama, Isao; Matsumoto, Kiyoshi

    2012-01-01

    We measured and analyzed the electrochemical impedance of carbon nanotube (CNT) probe electrodes fabricated through the physical separation of insulated CNT bridges. The fabricated CNT electrodes were free-standing CNTs that were completely covered with an insulator, except for their tips. Typical dimensions of the nanoelectrodes were 1–10 nm in CNT diameter, 80–300 nm in insulator diameter, 0.5–4 μm in exposed CNT length and 1–10 μm in probe length. The electrochemical impedance at frequencies ranging from 40 Hz to 1 MHz was measured in physiological saline. The measured impedance of the CNT electrode was constant at 32 MΩ at frequencies below 1 kHz and was inversely proportional to frequency at frequencies above 10 kHz. By means of comparison with the parasitic capacitive impedance of the insulator membrane, we confirmed that the electrode was sufficiently insulated such that the measured constant impedance was given by the exposed CNT tip. Consequently, we can use the CNT electrode for highly localized electrochemical impedance measurements below 1 kHz. Considering an equivalent circuit and the nanoscopic dimensions of the CNT electrode, we demonstrated that the constant impedance was governed by diffusion impedance, whereas the solution resistance, charge-transfer resistance and double-layer capacitance were negligible. (paper)

  19. The standardized EEG electrode array of the IFCN.

    Science.gov (United States)

    Seeck, Margitta; Koessler, Laurent; Bast, Thomas; Leijten, Frans; Michel, Christoph; Baumgartner, Christoph; He, Bin; Beniczky, Sándor

    2017-10-01

    Standardized EEG electrode positions are essential for both clinical applications and research. The aim of this guideline is to update and expand the unifying nomenclature and standardized positioning for EEG scalp electrodes. Electrode positions were based on 20% and 10% of standardized measurements from anatomical landmarks on the skull. However, standard recordings do not cover the anterior and basal temporal lobes, which is the most frequent source of epileptogenic activity. Here, we propose a basic array of 25 electrodes including the inferior temporal chain, which should be used for all standard clinical recordings. The nomenclature in the basic array is consistent with the 10-10-system. High-density scalp EEG arrays (64-256 electrodes) allow source imaging with even sub-lobar precision. This supplementary exam should be requested whenever necessary, e.g. search for epileptogenic activity in negative standard EEG or for presurgical evaluation. In the near future, nomenclature for high density electrodes arrays beyond the 10-10 system needs to be defined, to allow comparison and standardized recordings across centers. Contrary to the established belief that smaller heads needs less electrodes, in young children at least as many electrodes as in adults should be applied due to smaller skull thickness and the risk of spatial aliasing. Copyright © 2017 International Federation of Clinical Neurophysiology. Published by Elsevier B.V. All rights reserved.

  20. Binder-free carbon nanotube electrode for electrochemical removal of chromium.

    Science.gov (United States)

    Wang, Haitao; Na, Chongzheng

    2014-11-26

    Electrochemical treatment of chromium-containing wastewater has the advantage of simultaneously reducing hexavalent chromium (CrVI) and reversibly adsorbing the trivalent product (CrIII), thereby minimizing the generation of waste for disposal and providing an opportunity for resource reuse. The application of electrochemical treatment of chromium is often limited by the available electrochemical surface area (ESA) of conventional electrodes with flat surfaces. Here, we report the preparation and evaluation of carbon nanotube (CNT) electrodes consisting of vertically aligned CNT arrays directly grown on stainless steel mesh (SSM). We show that the 3-D organization of CNT arrays increases ESA up to 13 times compared to SSM. The increase of ESA is correlated with the length of CNTs, consistent with a mechanism of roughness-induced ESA enhancement. The increase of ESA directly benefits CrVI reduction by proportionally accelerating reduction without compromising the electrode's ability to adsorb CrIII. Our results suggest that the rational design of electrodes with hierarchical structures represents a feasible approach to improve the performance of electrochemical treatment of contaminated water.

  1. Piezoelectric Nanotube Array for Broadband High-Frequency Ultrasonic Transducer.

    Science.gov (United States)

    Liew, Weng Heng; Yao, Kui; Chen, Shuting; Tay, Francis Eng Hock

    2018-03-01

    Piezoelectric materials are vital in determining ultrasonic transducer and imaging performance as they offer the function for conversion between mechanical and electrical energy. Ultrasonic transducers with high-frequency operation suffer from performance degradation and fabrication difficulty of the demanded piezoelectric materials. Hence, we propose 1-D polymeric piezoelectric nanostructure with controlled nanoscale features to overcome the technical limitations of high-frequency ultrasonic transducers. For the first time, we demonstrate the integration of a well-aligned piezoelectric nanotube array to produce a high-frequency ultrasonic transducer with outstanding performance. We find that nanoconfinement-induced polarization orientation and unique nanotube structure lead to significantly improved piezoelectric and ultrasonic transducing performance over the conventional piezoelectric thin film. A large bandwidth, 126% (-6 dB), is achieved at high center frequency, 108 MHz. Transmission sensitivity of nanotube array is found to be 46% higher than that of the monolithic thin film transducer attributed to the improved electromechanical coupling effectiveness and impedance match. We further demonstrate high-resolution scanning, ultrasonic imaging, and photoacoustic imaging using the obtained nanotube array transducers, which is valuable for biomedical imaging applications in the future.

  2. A flexible capacitive tactile sensing array with floating electrodes

    International Nuclear Information System (INIS)

    Cheng, M-Y; Huang, X-H; Ma, C-W; Yang, Y-J

    2009-01-01

    In this work, we present the development of a capacitive tactile sensing array realized by using MEMS fabrication techniques and flexible printed circuit board (FPCB) technologies. The sensing array, which consists of two micromachined polydimethlysiloxane (PDMS) structures and a FPCB, will be used as the artificial skin for robot applications. Each capacitive sensing element comprises two sensing electrodes and a common floating electrode. The sensing electrodes and the metal interconnect for signal scanning are implemented on the FPCB, while the floating electrode is patterned on one of the PDMS structures. This special design can effectively reduce the complexity of the device structure and thus makes the device highly manufacturable. The characteristics of the devices with different dimensions are measured and discussed. The corresponding scanning circuits are also designed and implemented. The tactile images induced by the PMMA stamps of different shapes are also successfully captured by a fabricated 8 × 8 array

  3. Challenging aspects of contemporary cochlear implant electrode array design.

    Science.gov (United States)

    Mistrík, Pavel; Jolly, Claude; Sieber, Daniel; Hochmair, Ingeborg

    2017-12-01

    A design comparison of current perimodiolar and lateral wall electrode arrays of the cochlear implant (CI) is provided. The focus is on functional features such as acoustic frequency coverage and tonotopic mapping, battery consumption and dynamic range. A traumacity of their insertion is also evaluated. Review of up-to-date literature. Perimodiolar electrode arrays are positioned in the basal turn of the cochlea near the modiolus. They are designed to initiate the action potential in the proximity to the neural soma located in spiral ganglion. On the other hand, lateral wall electrode arrays can be inserted deeper inside the cochlea, as they are located along the lateral wall and such insertion trajectory is less traumatic. This class of arrays targets primarily surviving neural peripheral processes. Due to their larger insertion depth, lateral wall arrays can deliver lower acoustic frequencies in manner better corresponding to cochlear tonotopicity. In fact, spiral ganglion sections containing auditory nerve fibres tuned to low acoustic frequencies are located deeper than 1 and half turn inside the cochlea. For this reason, a significant frequency mismatch might be occurring for apical electrodes in perimodiolar arrays, detrimental to speech perception. Tonal languages such as Mandarin might be therefore better treated with lateral wall arrays. On the other hand, closer proximity to target tissue results in lower psychophysical threshold levels for perimodiolar arrays. However, the maximal comfort level is also lower, paradoxically resulting in narrower dynamic range than that of lateral wall arrays. Battery consumption is comparable for both types of arrays. Lateral wall arrays are less likely to cause trauma to cochlear structures. As the current trend in cochlear implantation is the maximal protection of residual acoustic hearing, the lateral wall arrays seem more suitable for hearing preservation CI surgeries. Future development could focus on combining the

  4. Developing Barbed Microtip-Based Electrode Arrays for Biopotential Measurement

    Directory of Open Access Journals (Sweden)

    Li-Sheng Hsu

    2014-07-01

    Full Text Available This study involved fabricating barbed microtip-based electrode arrays by using silicon wet etching. KOH anisotropic wet etching was employed to form a standard pyramidal microtip array and HF/HNO3 isotropic etching was used to fabricate barbs on these microtips. To improve the electrical conductance between the tip array on the front side of the wafer and the electrical contact on the back side, a through-silicon via was created during the wet etching process. The experimental results show that the forces required to detach the barbed microtip arrays from human skin, a polydimethylsiloxane (PDMS polymer, and a polyvinylchloride (PVC film were larger compared with those required to detach microtip arrays that lacked barbs. The impedances of the skin-electrode interface were measured and the performance levels of the proposed dry electrode were characterized. Electrode prototypes that employed the proposed tip arrays were implemented. Electroencephalogram (EEG and electrocardiography (ECG recordings using these electrode prototypes were also demonstrated.

  5. Surface-conduction electron-emitter characteristics and fabrication based on vertically aligned carbon nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Shih, Yi-Ting [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Li, Kuan-Wei [Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Honda, Shin-ichi [Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280 (Japan); Lin, Pao-Hung; Huang, Ying-Sheng [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Lee, Kuei-Yi, E-mail: kylee@mail.ntust.edu.tw [Graduate Institute of Electro-Optical Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China); Department of Electronic and Computer Engineering, National Taiwan University of Science and Technology, No. 43, Section 4, Keelung Road, Taipei 10607, Taiwan (China)

    2017-06-01

    Graphical abstract: The pattern design provides a new structure of surface-conduction electron-emitter display (SED). Delta-star shaped vertically aligned CNT (VACNT) arrays with 20o tips can simultaneously provide three emitters to bombard the sides of equilateral triangles pattern of VACNT, which produces numerous secondary electrons and enhance the SED efficiency. - Highlights: • The carbon nanotube (CNT) has replaced palladium oxide (PdO) as the electrode material for surface-conduction electron-emitter (SCE) applications. • The vertically aligned CNT (VACNT) arrays with 20° tips of the delta-star arrangement are used as cathodes that easily emit electrons. The cathode pattern simultaneously provides three emitters to bombard the sides of equilateral triangles pattern of VACNT. • The VACNT arrays were covered with magnesium oxide (MgO) nanostructures to promote the surface-conduction electron-emitter display (SED) efficiency (η). • The η was stably maintained in the 75–85% range. The proposed design provides a facile new method for developing SED applications. - Abstract: The carbon nanotube (CNT) has replaced palladium oxide (PdO) as the electrode material for surface-conduction electron-emitter (SCE) applications. Vertically aligned CNT arrays with a delta-star arrangement were patterned and synthesized onto a quartz substrate using photolithography and thermal chemical vapor deposition. Delta-star shaped VACNT arrays with 20° tips are used as cathodes that easily emit electrons because of their high electrical field gradient. In order to improve the field emission and secondary electrons (SEs) in SCE applications, magnesium oxide (MgO) nanostructures were coated onto the VACNT arrays to promote the surface-conduction electron-emitter display (SED) efficiency (η). According to the definition of η in SCE applications, in this study, the η was stably maintained in the 75–85% range. The proposed design provides a facile new method for

  6. A novel screen-printed electrode array for rapid high-throughput detection.

    Science.gov (United States)

    Mu, Shuai; Wang, Xiao; Li, Yuan-Ting; Wang, Yang; Li, Da-Wei; Long, Yi-Tao

    2012-07-21

    A novel multi-channel electrode array sensing device was fabricated by screen-printing techniques using 96-well plate as the template. To confirm its practical value, we developed a one-step preparation of multi-walled carbon nanotubes (MWCNTs) doped electrode array by an ink containing MWCNTs, which was applied to the simultaneous detection of a variety of biological samples and environmental pollutants. Results demonstrated that the designed sensing device could carry out the multiple measurements of different analytes at the same time, while MWCNTs enhanced the electrocatalytic activity of electrodes toward electroactive molecules. The required amount of each sample was only ∼200 μL. Moreover, the excellent differential pulse voltammetric (DPV) response toward dopamine, hydroquinone and catechol was obtained and the detection limits was determined to be 0.337, 0.289 and 0.369 μM, respectively. Comparing it with the traditional screen-printed electrode (SPE), this sensing device possesses the advantages of high-throughput, fast electron transfer rate for electrodes, short-time analysis and low sample consumption.

  7. Drying induced upright sliding and reorganization of carbon nanotube arrays

    International Nuclear Information System (INIS)

    Li Qingwen; De Paula, Raymond; Zhang Xiefei; Zheng Lianxi; Arendt, Paul N; Mueller, Fred M; Zhu, Y T; Tu Yi

    2006-01-01

    Driven by capillary force, wet carbon nanotube (CNT) arrays have been found to reorganize into cellular structures upon drying. During the reorganization process, individual CNTs are firmly attached to the substrate and have to lie down on the substrate at cell bottoms, forming closed cells. Here we demonstrate that by modifying catalyst structures, the adhesion of CNTs to the substrate can be weakened. Upon drying such CNT arrays, CNTs may slide away from their original sites on the surface and self-assemble into cellular patterns with bottoms open. It is also found that the sliding distance of CNTs increases with array height, and drying millimetre tall arrays leads to the sliding of CNTs over a few hundred micrometres and the eventual self-assembly into discrete islands. By introducing regular vacancies in CNT arrays, CNTs may be manipulated into different patterns

  8. 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.

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

    International Nuclear Information System (INIS)

    Su, Y.; Zhitomirsky, I.

    2015-01-01

    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

  10. Built-in test of electrode degradation of multi-electrode array biosensors

    NARCIS (Netherlands)

    Liu, H.Y.; Dumas, N.; Richardson, A.; Heal, R.; Kerkhoff, Hans G.

    2006-01-01

    Micro-electrode array (MEA) is a widely used platform in biosensor systems, which provide a technology in communicating with micro chemical and biological world. This paper addresses hte topic of testing micro electrode degradation for MEAs, which is a common encountered damage during its

  11. Fabrication and structural characterization of highly ordered titania nanotube arrays

    Science.gov (United States)

    Shi, Hongtao; Ordonez, Rosita

    Titanium (Ti) dioxide nanotubes have drawn much attention in the past decade due to the fact that titania is an extremely versatile material with a variety of technological applications. Anodizing Ti in different electrolytes has proved to be quite successful so far in creating the nanotubes, however, their degree of order is still not nearly as good as nanoporous anodic alumina. In this work, we first deposit a thin layer of aluminum (Al) onto electropolished Ti substrates, using thermal evaporation. Such an Al layer is then anodized in 0.3 M oxalic acid, forming an ordered nanoporous alumina mask on top of Ti. Afterwards, the anodization of Ti is accomplished at 20 V in solutions containing 1 M NaH2PO4 and 0.5% HF or H2SO4, which results in the creation of ordered titania nanotube arrays. The inner pore diameter of the nanotubes can be tuned from ~50 nm to ~75 nm, depending on the anodization voltage applied to Al or Ti. X-ray diffractometry shows the as-grown titania nanotubes are amorphous. Samples annealed at different temperatures in ambient atmosphere will be also reported.

  12. A Porous Perchlorate-Doped Polypyrrole Nanocoating on Nickel Nanotube Arrays for Stable Wide-Potential-Window Supercapacitors.

    Science.gov (United States)

    Chen, Gao-Feng; Li, Xian-Xia; Zhang, Li-Yi; Li, Nan; Ma, Tian Yi; Liu, Zhao-Qing

    2016-09-01

    A bottom-up synthetic strategy is developed to fabricate a highly porous wave-superposed perchlorate-doped polypyrrole nanocoating on nickel nanotube arrays. The delicate nanostructure and the unique surface chemistry synergistically endow the obtained electrode with revealable pseudocapacitance, large operating potential window, and excellent cycling stability, which are highly promising for both asymmetric and symmetric supercapacitors. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. System of fabricating a flexible electrode array

    Energy Technology Data Exchange (ETDEWEB)

    Krulevitch, Peter [Pleasanton, CA; Polla, Dennis L [Roseville, MN; Maghribi, Mariam N [Davis, CA; Hamilton, Julie [Tracy, CA; Humayun, Mark S [La Canada, CA; Weiland, James D [Valencia, CA

    2012-01-28

    An image is captured or otherwise converted into a signal in an artificial vision system. The signal is transmitted to the retina utilizing an implant. The implant consists of a polymer substrate made of a compliant material such as poly(dimethylsiloxane) or PDMS. The polymer substrate is conformable to the shape of the retina. Electrodes and conductive leads are embedded in the polymer substrate. The conductive leads and the electrodes transmit the signal representing the image to the cells in the retina. The signal representing the image stimulates cells in the retina.

  14. System of fabricating a flexible electrode array

    Science.gov (United States)

    Krulevitch, Peter; Polla, Dennis L.; Maghribi, Mariam N.; Hamilton, Julie; Humayun, Mark S.; Weiland, James D.

    2010-10-12

    An image is captured or otherwise converted into a signal in an artificial vision system. The signal is transmitted to the retina utilizing an implant. The implant consists of a polymer substrate made of a compliant material such as poly(dimethylsiloxane) or PDMS. The polymer substrate is conformable to the shape of the retina. Electrodes and conductive leads are embedded in the polymer substrate. The conductive leads and the electrodes transmit the signal representing the image to the cells in the retina. The signal representing the image stimulates cells in the retina.

  15. Fabrication of polyaniline/graphene/titania nanotube arrays nanocomposite and their application in supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Hua; Gan, Mengyu; Ma, Li, E-mail: mlsys607@126.com; Yu, Lei; Hu, Haifeng; Yang, Fangfang; Li, Yanjun; Ge, Chengqiang

    2015-05-05

    Highlights: • The PANI/graphene/TiO{sub 2} nanotube arrays were fabricated firstly. • The composite shows a high specific capacitance and superior rate capability. • A high capacity retention rate of 91% after 1000 cycles can be achieved. • The composite possesses a novel three-dimensional (3D) highly ordered nanostructure. • TiO{sub 2} NTs enhance the adhesion between PANI and substrate. - Abstract: Polyaniline/graphene/titania nanotube arrays (PGTNs) nanocomposite as a supercapacitor electrode is fabricated by in-situ polymerization for the first time. Herein, the PGTNs possesses a novel three-dimensional (3D) highly ordered hybrid nanostructure consisting of coaxial polyaniline (PANI)/TiO{sub 2} nanotube arrays and graphene coated with PANI on the surface of TiO{sub 2} in some degree. The synthesized three-dimensional PGTNs is characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Raman spectroscopy, and its electrochemical performance is measured by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge. The maximum specific capacitance of PGTNs is as high as 933 F g{sup −1} at current density of 0.75 A g{sup −1} and the specific capacitance retains 91% of the initial after constant charge–discharge 1000 cycles. The improved electrochemical performance is due to the 3D nanostructure, which effectively prevents the mechanical deformation during the fast charge/discharge process and favors the diffusion of the electrolyte ions into the inner region of active materials. The composite electrode material is very promising for the next generation of high-performance electrochemical supercapacitors.

  16. Fabrication of polyaniline/graphene/titania nanotube arrays nanocomposite and their application in supercapacitors

    International Nuclear Information System (INIS)

    Huang, Hua; Gan, Mengyu; Ma, Li; Yu, Lei; Hu, Haifeng; Yang, Fangfang; Li, Yanjun; Ge, Chengqiang

    2015-01-01

    Highlights: • The PANI/graphene/TiO 2 nanotube arrays were fabricated firstly. • The composite shows a high specific capacitance and superior rate capability. • A high capacity retention rate of 91% after 1000 cycles can be achieved. • The composite possesses a novel three-dimensional (3D) highly ordered nanostructure. • TiO 2 NTs enhance the adhesion between PANI and substrate. - Abstract: Polyaniline/graphene/titania nanotube arrays (PGTNs) nanocomposite as a supercapacitor electrode is fabricated by in-situ polymerization for the first time. Herein, the PGTNs possesses a novel three-dimensional (3D) highly ordered hybrid nanostructure consisting of coaxial polyaniline (PANI)/TiO 2 nanotube arrays and graphene coated with PANI on the surface of TiO 2 in some degree. The synthesized three-dimensional PGTNs is characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Raman spectroscopy, and its electrochemical performance is measured by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge/discharge. The maximum specific capacitance of PGTNs is as high as 933 F g −1 at current density of 0.75 A g −1 and the specific capacitance retains 91% of the initial after constant charge–discharge 1000 cycles. The improved electrochemical performance is due to the 3D nanostructure, which effectively prevents the mechanical deformation during the fast charge/discharge process and favors the diffusion of the electrolyte ions into the inner region of active materials. The composite electrode material is very promising for the next generation of high-performance electrochemical supercapacitors

  17. Self-assembled ordered carbon-nanotube arrays and membranes.

    Energy Technology Data Exchange (ETDEWEB)

    Overmyer, Donald L.; Siegal, Michael P.; Yelton, William Graham

    2004-11-01

    Imagine free-standing flexible membranes with highly-aligned arrays of carbon nanotubes (CNTs) running through their thickness. Perhaps with both ends of the CNTs open for highly controlled nanofiltration? Or CNTs at heights uniformly above a polymer membrane for a flexible array of nanoelectrodes or field-emitters? How about CNT films with incredible amounts of accessible surface area for analyte adsorption? These self-assembled crystalline nanotubes consist of multiple layers of graphene sheets rolled into concentric cylinders. Tube diameters (3-300 nm), inner-bore diameters (2-15 nm), and lengths (nanometers - microns) are controlled to tailor physical, mechanical, and chemical properties. We proposed to explore growth and characterize nanotube arrays to help determine their exciting functionality for Sandia applications. Thermal chemical vapor deposition growth in a furnace nucleates from a metal catalyst. Ordered arrays grow using templates from self-assembled hexagonal arrays of nanopores in anodized-aluminum oxide. Polymeric-binders can mechanically hold the CNTs in place for polishing, lift-off, and membrane formation. The stiffness, electrical and thermal conductivities of CNTs make them ideally suited for a wide-variety of possible applications. Large-area, highly-accessible gas-adsorbing carbon surfaces, superb cold-cathode field-emission, and unique nanoscale geometries can lead to advanced microsensors using analyte adsorption, arrays of functionalized nanoelectrodes for enhanced electrochemical detection of biological/explosive compounds, or mass-ionizers for gas-phase detection. Materials studies involving membrane formation may lead to exciting breakthroughs in nanofiltration/nanochromatography for the separation of chemical and biological agents. With controlled nanofilter sizes, ultrafiltration will be viable to separate and preconcentrate viruses and many strains of bacteria for 'down-stream' analysis.

  18. Effects of carbon nanotube arrays on nucleate pool boiling

    OpenAIRE

    Ujereh, Sebastine; Fisher, Timothy; Mudawar, Issam

    2007-01-01

    Experiments were performed to assess the impact coating silicon and copper substrates with nanotubes (CNTs) have on pool boiling performance. Different CNT array densities and area coverages were tested on 1.27 1.27 mm2 samples in FC-72. The CNT preparation techniques used provided strong adherence of CNTs to both substrate materials. Very small contact angle enabled deep penetration of FC-72 liquid inside surface cavities of smooth uncoated silicon surfaces, requiring unusually high surface...

  19. Highly aligned carbon nanotube arrays fabricated by bias sputtering

    International Nuclear Information System (INIS)

    Hayashi, Nobuyuki; Honda, Shin-ichi; Tsuji, Keita; Lee, Kuei-Yi; Ikuno, Takashi; Fujimoto, Keiichi; Ohkura, Shigeharu; Katayama, Mitsuhiro; Oura, Kenjiro; Hirao, Takashi

    2003-01-01

    Vertically aligned carbon nanotube (CNT) arrays have been successfully grown on Si substrates by dc bias sputtering. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations revealed that the resultant arrays consisted of dense CNTs with diameters of 40-60 nm and lengths of 300-400 nm. The CNTs were found to have a bamboo-like structure at the end of which metallic nanoparticle was formed, indicating tip growth mechanism. The energy enhancement of carbon particles is a key factor for synthesis of CNTs using dc bias sputtering system

  20. Nanoparticle fractionation using an aligned carbon nanotube array

    Energy Technology Data Exchange (ETDEWEB)

    Lim Xiaodai [NUS Graduate School for Integrative Sciences and Engineering (NGS), Centre for Life Sciences (CeLS), 05-01, 28 Medical Drive, 117456 (Singapore); Xu Hairuo; Chin, Wee Shong [Department of Chemistry, Faculty of Science, National University of Singapore, 3 Science Drive 3, 117543 (Singapore); Nicole Chew, Yi Hui; Phua, Yi Hui [Dunman High School, 10 Tanjong Rhu Road, 436895 (Singapore); Sie, Edbert Jarvis; Sum, Tze Chien [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 637371 (Singapore); Chia, Guo Hao; Sow, Chorng-Haur, E-mail: chmcws@nus.edu.sg, E-mail: physowch@nus.edu.sg [Department of Physics, Blk S12, Faculty of Science, National University of Singapore, 2 Science Drive 3, 117542 (Singapore)

    2010-07-23

    A technique utilizing the capillary assisted sieving capability of carbon nanotubes (CNTs) to achieve fractionation of nanoparticles of small size distribution is presented. By dipping aligned CNT arrays into a solution comprising different sized quantum dots (QDs), size-selective gradient decoration of QDs onto CNTs is achieved. The fractionating capability of CNTs is also demonstrated for poly-dispersed manganese doped zinc sulfide nanoparticles and QDs of varying sizes and chemical compositions, which we attribute to the size-selective sieving effect of CNTs. By controlling the terminating point for the flow of QDs across the CNT array, a QD size specific CNT/QD hybrid structure is achieved.

  1. Fabrication of Pillar Shaped Electrode Arrays for Artificial Retinal Implants

    Directory of Open Access Journals (Sweden)

    Sung June Kim

    2008-09-01

    Full Text Available Polyimide has been widely applied to neural prosthetic devices, such as the retinal implants, due to its well-known biocompatibility and ability to be micropatterned. However, planar films of polyimide that are typically employed show a limited ability in reducing the distance between electrodes and targeting cell layers, which limits site resolution for effective multi-channel stimulation. In this paper, we report a newly designed device with a pillar structure that more effectively interfaces with the target. Electrode arrays were successfully fabricated and safely implanted inside the rabbit eye in suprachoroidal space. Optical Coherence Tomography (OCT showed well-preserved pillar structures of the electrode without damage. Bipolar stimulation was applied through paired sites (6:1 and the neural responses were successfully recorded from several regions in the visual cortex. Electrically evoked cortical potential by the pillar electrode array stimulation were compared to visual evoked potential under full-field light stimulation.

  2. 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.

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

    International Nuclear Information System (INIS)

    Salinas-Torres, David; Huerta, Francisco; Montilla, Francisco; Morallon, Emilia

    2011-01-01

    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 π-π 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.

  4. Graphene Transparent Conductive Electrodes for Next- Generation Microshutter Arrays

    Science.gov (United States)

    Li, Mary; Sultana, Mahmooda; Hess, Larry

    2012-01-01

    Graphene is a single atomic layer of graphite. It is optically transparent and has high electron mobility, and thus has great potential to make transparent conductive electrodes. This invention contributes towards the development of graphene transparent conductive electrodes for next-generation microshutter arrays. The original design for the electrodes of the next generation of microshutters uses indium-tin-oxide (ITO) as the electrode material. ITO is widely used in NASA flight missions. The optical transparency of ITO is limited, and the material is brittle. Also, ITO has been getting more expensive in recent years. The objective of the invention is to develop a graphene transparent conductive electrode that will replace ITO. An exfoliation procedure was developed to make graphene out of graphite crystals. In addition, large areas of single-layer graphene were produced using low-pressure chemical vapor deposition (LPCVD) with high optical transparency. A special graphene transport procedure was developed for transferring graphene from copper substrates to arbitrary substrates. The concept is to grow large-size graphene sheets using the LPCVD system through chemical reaction, transfer the graphene film to a substrate, dope graphene to reduce the sheet resistance, and pattern the film to the dimension of the electrodes in the microshutter array. Graphene transparent conductive electrodes are expected to have a transparency of 97.7%. This covers the electromagnetic spectrum from UV to IR. In comparison, ITO electrodes currently used in microshutter arrays have 85% transparency in mid-IR, and suffer from dramatic transparency drop at a wavelength of near-IR or shorter. Thus, graphene also has potential application as transparent conductive electrodes for Schottky photodiodes in the UV region.

  5. Facile fabrication of organic/inorganic nanotube heterojunction arrays for enhanced photoelectrochemical water splitting

    Science.gov (United States)

    Chen, Yingzhi; Li, Aoxiang; Yue, Xiaoqi; Wang, Lu-Ning; Huang, Zheng-Hong; Kang, Feiyu; Volinsky, Alex A.

    2016-07-01

    Organic/inorganic heterojunction photoanodes are appealing for making concurrent use of the highly photoactive organic semiconductors, and the efficient dielectric screening provided by their inorganic counterparts. In the present work, organic/inorganic nanotube heterojunction arrays composed of TiO2 nanotube arrays and a semiconducting N,N-(dicyclohexyl) perylene-3,4,9,10-tetracarboxylic diimide (PDi) layer were fabricated for photoelectrochemical water splitting. In this arrayed architecture, a PDi layer with a tunable thickness was coated on anodic TiO2 nanotube arrays by physical vapor deposition, which is advantageous for the formation of a uniform layer and an adequate interface contact between PDi and TiO2. The obtained PDi/TiO2 junction exhibited broadened visible light absorption, and an effective interface for enhanced photogenerated electron-hole separation, which is supported by the reduced charge transfer resistance and prolonged excitation lifetime via impedance spectroscopy analysis and fluorescence emission decay investigations. Consequently, such a heterojunction photoanode was photoresponsive to a wide visible light region of 400-600 nm, and thus demonstrated a highly enhanced photocurrent density at 1.23 V vs. a reversible hydrogen electrode. Additionally, the durability of such a photoanode can be guaranteed after long-time illumination because of the geometrical restraint imposed by the PDi aggregates. These results pave the way to discover new organic/inorganic assemblies for high-performance photoelectric applications and device integration.Organic/inorganic heterojunction photoanodes are appealing for making concurrent use of the highly photoactive organic semiconductors, and the efficient dielectric screening provided by their inorganic counterparts. In the present work, organic/inorganic nanotube heterojunction arrays composed of TiO2 nanotube arrays and a semiconducting N,N-(dicyclohexyl) perylene-3,4,9,10-tetracarboxylic diimide (PDi

  6. Polymyxin-coated Au and carbon nanotube electrodes for stable [NiFe]-hydrogenase film voltammetry.

    NARCIS (Netherlands)

    Hoeben, F.J.M.; Heller, I.; Albracht, S.P.J.; Dekker, C.; Lemay, S.G.; Heering, H.A.

    2008-01-01

    We report on the use of polymyxin (PM), a cyclic cationic lipodecapeptide, as an electrode modifier for studying protein film voltammetry (PFV) on Au and single-walled carbon nanotube (SWNT) electrodes. Pretreating the electrodes with PM allows for the subsequent immobilization of an active

  7. Copper-encapsulated vertically aligned carbon nanotube arrays.

    Science.gov (United States)

    Stano, Kelly L; Chapla, Rachel; Carroll, Murphy; Nowak, Joshua; McCord, Marian; Bradford, Philip D

    2013-11-13

    A new procedure is described for the fabrication of vertically aligned carbon nanotubes (VACNTs) that are decorated, and even completely encapsulated, by a dense network of copper nanoparticles. The process involves the conformal deposition of pyrolytic carbon (Py-C) to stabilize the aligned carbon-nanotube structure during processing. The stabilized arrays are mildly functionalized using oxygen plasma treatment to improve wettability, and they are then infiltrated with an aqueous, supersaturated Cu salt solution. Once dried, the salt forms a stabilizing crystal network throughout the array. After calcination and H2 reduction, Cu nanoparticles are left decorating the CNT surfaces. Studies were carried out to determine the optimal processing parameters to maximize Cu content in the composite. These included the duration of Py-C deposition and system process pressure as well as the implementation of subsequent and multiple Cu salt solution infiltrations. The optimized procedure yielded a nanoscale hybrid material where the anisotropic alignment from the VACNT array was preserved, and the mass of the stabilized arrays was increased by over 24-fold because of the addition of Cu. The procedure has been adapted for other Cu salts and can also be used for other metal salts altogether, including Ni, Co, Fe, and Ag. The resulting composite is ideally suited for application in thermal management devices because of its low density, mechanical integrity, and potentially high thermal conductivity. Additionally, further processing of the material via pressing and sintering can yield consolidated, dense bulk composites.

  8. Anodic Fabrication of Ti-Nb-Zr-O Nanotube Arrays

    Directory of Open Access Journals (Sweden)

    Qiang Liu

    2014-01-01

    Full Text Available Highly ordered Ti-Nb-Zr-O nanotube arrays were fabricated through pulse anodic oxidation of Ti-Nb-Zr alloy in 1 M NaH2PO4 containing 0.5 wt% HF electrolytes. The effect of anodization parameters and Zr content on the microstructure and composition of Ti-Nb-Zr-O nanotubes was investigated using a scanning electron microscope equipped with energy dispersive X-ray analysis. It was found that length of the Ti-Nb-Zr-O nanotubes increased with increase of Zr contents. The diameter and the length of Ti-Nb-Zr-O nanotubes could be controlled by pulse voltage. XRD analysis of Ti-Nb-Zr-O samples annealed at 500°C in air indicated that the (101 diffraction peaks shifted from 25.78° to 25.05° for annealed Ti-Nb-Zr-O samples with different Zr contents because of larger lattice parameter of Ti-Nb-Zr-O compared to that of undoped TiO2.

  9. Synthesis of highly-ordered TiO2 nanotube arrays with tunable sizes

    Science.gov (United States)

    Wang, Xian; Zha, Chenyang; Ji, Cheng; Zhang, Xiaoyan; Shen, Liming; Wang, Yifeng; Gupta, Arunava; Yoriya, Sorachon; Bao, Ningzhong

    2014-09-01

    Vertically-oriented one-dimensional TiO2 nanotube (TNT) arrays have been fabricated by anodic oxidation using different electrolyte solvents, including ethylene glycol (EG), diethylene glycol (DEG), and dimethyl sulfoxide (DMSO), in the presence of hydrofluoric acid (HF) or ammonium fluoride (NH4F). The influence of synthetic conditions, including the nature of the electrolyte and anodization voltage, on nanotube microstructure has been systematically investigated. Highly-ordered TNTs with tube length of ˜0.5-26.7 μm, inner diameter of ˜13-201 nm, and outer diameter of ˜28-250 nm have been obtained. The conversion of as-prepared TNT arrays from amorphous phase to crystalline structure has been achieved by a post-synthetic annealing at 500 °C for 3 h in oxygen ambient. The TNT arrays with tunable sizes and structures are attractive for use as electrode materials in fabrication of thin film solar cells and highly active photocatalysts.

  10. Synthesis of highly-ordered TiO2 nanotube arrays with tunable sizes

    International Nuclear Information System (INIS)

    Wang, Xian; Zha, Chenyang; Ji, Cheng; Zhang, Xiaoyan; Shen, Liming; Wang, Yifeng; Bao, Ningzhong; Gupta, Arunava; Yoriya, Sorachon

    2014-01-01

    Vertically-oriented one-dimensional TiO 2 nanotube (TNT) arrays have been fabricated by anodic oxidation using different electrolyte solvents, including ethylene glycol (EG), diethylene glycol (DEG), and dimethyl sulfoxide (DMSO), in the presence of hydrofluoric acid (HF) or ammonium fluoride (NH 4 F). The influence of synthetic conditions, including the nature of the electrolyte and anodization voltage, on nanotube microstructure has been systematically investigated. Highly-ordered TNTs with tube length of ∼0.5–26.7 μm, inner diameter of ∼13–201 nm, and outer diameter of ∼28–250 nm have been obtained. The conversion of as-prepared TNT arrays from amorphous phase to crystalline structure has been achieved by a post-synthetic annealing at 500 °C for 3 h in oxygen ambient. The TNT arrays with tunable sizes and structures are attractive for use as electrode materials in fabrication of thin film solar cells and highly active photocatalysts. (paper)

  11. Double-walled ZrO{sub 2} nanotube array. Preparation and enhanced photocatalytic activity

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Chaorui; Hu, Shengliang; Chang, Qing; Wang, Yanzhong [School of Materials Science and Engineering, North University of China, Taiyuan (China); Yang, Jinlong [School of Materials Science and Engineering, North University of China, Taiyuan (China); School of Materials Science and Engineering, Tsinghua University, Beijing (China)

    2017-11-15

    This work demonstrates the formation of self-ordered double-walled ZrO{sub 2} nanotube array via electrochemical anodization in glycerol-based electrolyte. Compared with its counterpart of single-walled ZrO{sub 2} nanotube array, the tube wall of double-walled ZrO{sub 2} nanotube split into outer and inner layers for the decomposition of glycerol during anodization process. Moreover, the double-walled structure showed its advantage of achieving improved utilization of light and higher specific surface area of nanotube array. Due to the unique double-walled structure, the double-walled ZrO{sub 2} nanotube array exhibited better photocatalytic activity than the single-walled ZrO{sub 2} nanotube array. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Influence of anodization parameters on the morphology of TiO 2 nanotube arrays

    Science.gov (United States)

    Omidvar, Hamid; Goodarzi, Saba; Seif, Ahmad; Azadmehr, Amir R.

    2011-07-01

    TiO 2 nanotube arrays can be fabricated by electrochemical anodization in organic and inorganic electrolytes. Morphology of these nanotube arrays changes when anodization parameters such as applied voltage, type of electrolyte, time and temperature are varied. Nanotube arrays fabricated by anodization of commercial titanium in electrolytes containing NH 4F solution and either sulfuric or phosphoric acid were studied at room temperature; time of anodization was kept constant. Applied voltage, fluoride ion concentration, and acid concentrations were varied and their influences on TiO 2 nanotubes were investigated. The current density of anodizing was recorded by computer controlled digital multimeter. The surface morphology (top-view) of nanotube arrays were observed by SEM. The nanotube arrays in this study have inner diameters in range of 40-80 nm.

  13. Direct electrodeposition of gold nanotube arrays of rough and porous wall by cyclic voltammetry and its applications of simultaneous determination of ascorbic acid and uric acid

    International Nuclear Information System (INIS)

    Yang Guangming; Li Ling; Jiang Jinhe; Yang Yunhui

    2012-01-01

    Gold nanotube arrays of rough and porous wall has been synthesized by direct electrodeposition with cyclic voltammetry utilizing anodic aluminum oxide template (AAO) and polycarbonate membrane (PC) during short time (only 3 min and 2 min, respectively). The mechanism of the direct electrodeposition of gold nanotube arrays by cyclic voltammetry (CV) has been discussed. The morphological characterizations of the gold nanotube arrays have been investigated by scanning electron microscopy (SEM). A simultaneous determination of ascorbic acid (AA) and uric acid (UA) by differential pulse voltammetry (DPV) was constructed by attaching gold nanotube arrays (using AAO) onto the surface of a glassy carbon electrode (GCE). The electrochemical behavior of AA and UA at this modified electrode has been studied by CV and differential pulse voltammetry (DPV). The sensor offers an excellent response for AA and UA and the linear response range for AA and UA were 1.02 × 10 −7 –5.23 × 10 −4 mol L −1 and 1.43 × 10 −7 –4.64 × 10 −4 mol L −1 , the detection limits were 1.12 × 10 −8 mol L −1 and 2.24 × 10 −8 mol L −1 , respectively. This sensor shows good regeneration, stability and selectivity and has been used for the determination of AA and UA in real human urine and serum samples with satisfied results. - Graphical abstract: The schematic diagram of formation of Au nanotube arrays (a) and the stepwise procedure of the sensor (b). Highlights: ► Gold nanotubes array has been synthesized by cyclic voltammetry. ► The mechanism of deposition of gold nanotube has been discussed. ► A determination of ascorbic acid and uric acid was constructed by gold array. ► A satisfied determination of samples can be obtained by this sensor.

  14. A Communications Link for an Implantable Electrode Array.

    Science.gov (United States)

    1984-12-01

    be gene -rated from the 256 electrodes in a 16 x 16 array which is narrow enough in bandwidth to be transmitted over a FM radio frequency carrier. The...MARCH 1973 DESIGNED FOR HIGH-SPE ED, MEDIUM-POWER SWITCHINGU AND GENERAL PURPOSE AMPLIFIER APPLICATIONS a hFE ... Guaranteed from 100 1pA to 500 mA

  15. A Platform for Manufacturable Stretchable Micro-electrode Arrays

    NARCIS (Netherlands)

    Khoshfetrat Pakazad, S.; Savov, A.; Braam, S.R.; Dekker, R.

    2012-01-01

    A platform for the batch fabrication of pneumatically actuated Stretchable Micro-Electrode Arrays (SMEAs) by using state-of-the-art micro-fabrication techniques and materials is demonstrated. The proposed fabrication process avoids the problems normally associated with processing of thin film

  16. Hot spot dynamics in carbon nanotube array devices.

    Science.gov (United States)

    Engel, Michael; Steiner, Mathias; Seo, Jung-Woo T; Hersam, Mark C; Avouris, Phaedon

    2015-03-11

    We report on the dynamics of spatial temperature distributions in aligned semiconducting carbon nanotube array devices with submicrometer channel lengths. By using high-resolution optical microscopy in combination with electrical transport measurements, we observe under steady state bias conditions the emergence of time-variable, local temperature maxima with dimensions below 300 nm, and temperatures above 400 K. On the basis of time domain cross-correlation analysis, we investigate how the intensity fluctuations of the thermal radiation patterns are correlated with the overall device current. The analysis reveals the interdependence of electrical current fluctuations and time-variable hot spot formation that limits the overall device performance and, ultimately, may cause device degradation. The findings have implications for the future development of carbon nanotube-based technologies.

  17. Additional magnetoelectric effect in electrode-arrayed magnetoelectric composite

    Directory of Open Access Journals (Sweden)

    D. A. Pan

    2014-11-01

    Full Text Available An electrode-arrayed magnetoelectric (ME composite was proposed, in which the positive and negative electrodes of the PZT-5H plate (Pb(Zr0.52Ti0.48O3 were equally divided into a 2 × 5 array, while the PZT plate remained intact. The ME voltage coefficients of these 10 sections were measured individually and in parallel/series modes. The magnetoelectric coefficient is doubled compared with un-arrayed condition, when the 10 sections are connected in parallel/series using an optimized connecting sequence derived from the charge matching rule. This scheme can also be applied to other types of layered magnetoelectric composites to obtain additional magnetoelectric effect from the original composite structure.

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

    KAUST Repository

    Xie, Xing; Ye, Meng; Hu, Liangbing; Liu, Nian; McDonough, James R.; Chen, Wei; Alshareef, Husam N.; Criddle, Craig S.; Cui, Yi

    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

  19. Electrochemical properties of Ti3+ doped Ag-Ti nanotube arrays coated with hydroxyapatite

    Science.gov (United States)

    Zhang, Hangzhou; Shi, Xiaoguo; Tian, Ang; Wang, Li; Liu, Chuangwei

    2018-04-01

    Ag-Ti nanotube array was prepared by simple anodic oxidation method and uniform hydroxyapatite were electrochemically deposited on the nanotubes, and then characterized by SEM, XRD, XPS and EIS. In order to investigate the influence of Ti3+ on the electrochemical deposition of hydroxyapatite on the nanotubes, the Ag-Ti nanotube array self-doped with Ti3+ was prepared by one step reduction method. The experiment results revealed that the Ti3+ can promote the grow rate of hydroxyapatite coatings on nanotube surface. The hydroxyapatite coated Ag-Ti nanotube arrays with Ti3+ exhibit excellent stability and higher corrosion resistance. Moreover, the compact and dense hydroxyapatite coating can also prevent the Ag atom erosion from the Ag-Ti nanotube.

  20. WIMP detection and slow ion dynamics in carbon nanotube arrays

    International Nuclear Information System (INIS)

    Cavoto, G.; Cirillo, E.N.M.; Cocina, F.; Ferretti, J.; Polosa, A.D.

    2016-01-01

    Large arrays of aligned carbon nanotubes (CNTs), open at one end, could be used as target material for the directional detection of weakly interacting dark matter particles (WIMPs). As a result of a WIMP elastic scattering on a CNT, a carbon ion might be injected in the body of the array and propagate through multiple collisions within the lattice. The ion may eventually emerge from the surface with open end CNTs, provided that its longitudinal momentum is large enough to compensate energy losses and its transverse momentum approaches the channeling conditions in a single CNT. Therefore, the angle formed between the WIMP wind apparent orientation and the direction of parallel carbon nanotube axes must be properly chosen. We focus on very low ion recoil kinetic energies, related to low mass WIMPs (∼ 11 GeV) where most of the existing experiments have low sensitivity. Relying on some exact results on two-dimensional lattices of circular obstacles, we study the low energy ion motion in the transverse plane with respect to CNT directions. New constraints are obtained on how to devise the CNT arrays to maximize the target channeling efficiency. (orig.)

  1. WIMP detection and slow ion dynamics in carbon nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Cavoto, G. [INFN Sezione di Roma, Rome (Italy); Cirillo, E.N.M. [Sapienza Universita di Roma, Dipartimento SBAI, Rome (Italy); Cocina, F. [Sapienza Universita di Roma, Dipartimento di Fisica, Rome (Italy); Ferretti, J. [Sapienza Universita di Roma, Dipartimento di Fisica (Italy); INFN Sezione di Roma, Rome (Italy); Polosa, A.D. [Sapienza Universita di Roma, Dipartimento di Fisica (Italy); CERN, Theory Division, Geneva (Switzerland); INFN Sezione di Roma, Rome (Italy)

    2016-06-15

    Large arrays of aligned carbon nanotubes (CNTs), open at one end, could be used as target material for the directional detection of weakly interacting dark matter particles (WIMPs). As a result of a WIMP elastic scattering on a CNT, a carbon ion might be injected in the body of the array and propagate through multiple collisions within the lattice. The ion may eventually emerge from the surface with open end CNTs, provided that its longitudinal momentum is large enough to compensate energy losses and its transverse momentum approaches the channeling conditions in a single CNT. Therefore, the angle formed between the WIMP wind apparent orientation and the direction of parallel carbon nanotube axes must be properly chosen. We focus on very low ion recoil kinetic energies, related to low mass WIMPs (∼ 11 GeV) where most of the existing experiments have low sensitivity. Relying on some exact results on two-dimensional lattices of circular obstacles, we study the low energy ion motion in the transverse plane with respect to CNT directions. New constraints are obtained on how to devise the CNT arrays to maximize the target channeling efficiency. (orig.)

  2. WIMP detection and slow ion dynamics in carbon nanotube arrays.

    Science.gov (United States)

    Cavoto, G; Cirillo, E N M; Cocina, F; Ferretti, J; Polosa, A D

    2016-01-01

    Large arrays of aligned carbon nanotubes (CNTs), open at one end, could be used as target material for the directional detection of weakly interacting dark matter particles (WIMPs). As a result of a WIMP elastic scattering on a CNT, a carbon ion might be injected in the body of the array and propagate through multiple collisions within the lattice. The ion may eventually emerge from the surface with open end CNTs, provided that its longitudinal momentum is large enough to compensate energy losses and its transverse momentum approaches the channeling conditions in a single CNT. Therefore, the angle formed between the WIMP wind apparent orientation and the direction of parallel carbon nanotube axes must be properly chosen. We focus on very low ion recoil kinetic energies, related to low mass WIMPs ([Formula: see text] GeV) where most of the existing experiments have low sensitivity. Relying on some exact results on two-dimensional lattices of circular obstacles, we study the low energy ion motion in the transverse plane with respect to CNT directions. New constraints are obtained on how to devise the CNT arrays to maximize the target channeling efficiency.

  3. 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 < 4 nm) on multiwalled 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.

  4. 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

  5. Laser-Assisted Simultaneous Transfer and Patterning of Vertically Aligned Carbon Nanotube Arrays on Polymer Substrates for Flexible Devices

    KAUST Repository

    In, Jung Bin; Lee, Daeho; Fornasiero, Francesco; Noy, Aleksandr; Grigoropoulos, Costas P.

    2012-01-01

    We demonstrate a laser-assisted dry transfer technique for assembling patterns of vertically aligned carbon nanotube arrays on a flexible polymeric substrate. A laser beam is applied to the interface of a nanotube array and a polycarbonate sheet

  6. Electrochemical characteristics of flexible micro supercapacitors with reduced graphene oxide-carbon nanotubes composite electrodes

    Science.gov (United States)

    Yang, Kyungwhan; Cho, Kyoungah; Kim, Sangsig

    2018-06-01

    In this study, we fabricate solid-state flexible micro-supercapacitors (MSCs) with reduced graphene oxide-carbon nanotube (rGO-CNT) composite electrodes and investigate the electrochemical characteristics by comparing with those of an MSC with rGO electrodes. Regarding the resistance-capacitance time constant and IR drop, the addition of CNTs into the rGO electrodes shows a significant effect owing to both the decrease in the resistance and the increase in the permeability of the electrolytes. Compared to the rGO MSCs, the rGO-CNT MSCs show an excellent areal capacitance of 2.6 mF/cm2, a smaller IR drop of 11 mV, a lower RC time constant of 6 ms, and faster charging/discharging rates with a high scan rate ability up to 100 V/s. The mechanical stability of the flexible rGO-CNT MSCs is verified by 1000 bending cycles. In addition, the electrochemical characteristics of the flexible rGO-CNT MSCs are maintained regardless of the MSC array type.

  7. Carbon Nanotubes as Counter Electrodes for Gratzel Solar Cells

    Science.gov (United States)

    Shodive, Hasan; Aliev, Ali; Zhang, Mei; Lee, Sergey; Baughman, Ray; Zakhidov, Anvar

    2006-03-01

    The role of interfaces is very critical for solar cell devices which use nanostructured materials. Dye Sensitized Solar Cells (DSSC) are devices which parts are interfacial in character and physico --chemical processes occur at the interface of two distinct media. DSSC are of great interest due to combination of their high efficiency and relatively low cost. An effective counterelectrode with high electrochemical activity is an important component of DSSC to enhance its practical utility. Presently used Pt coated ITO counterelectrode can not be applied in flexible DSSC architectures, while there is a growing need for flexible anodes which are transparent and have desired interface characteristics. In this work in order to search for such materials for counter electrode in dye sensitized solar cells, newly developed strong and transparent and modified carbon nanotube sheets [1] are used in interfacial counter electrode. To increase the electrochemical activity of the anode the CNT sheets are coated with highly conductive SWCNT and compared with pure multiwall CNT sheets. We show that the transparent sheets of SWCNT/MWCNT perform as a flexible anode and as electrochemical catalyst and also can be used in tandems of dye sensitized solar cells as transparent charge recombination or interconnect layers. [1] M. Zhang, S.Fang, A.Zakhidov, S.B.Lee, A.Aliev et.al., Science, 309,(2005) 1215

  8. Double-sided anodic titania nanotube arrays: a lopsided growth process.

    Science.gov (United States)

    Sun, Lidong; Zhang, Sam; Sun, Xiao Wei; Wang, Xiaoyan; Cai, Yanli

    2010-12-07

    In the past decade, the pore diameter of anodic titania nanotubes was reported to be influenced by a number of factors in organic electrolyte, for example, applied potential, working distance, water content, and temperature. All these were closely related to potential drop in the organic electrolyte. In this work, the essential role of electric field originating from the potential drop was directly revealed for the first time using a simple two-electrode anodizing method. Anodic titania nanotube arrays were grown simultaneously at both sides of a titanium foil, with tube length being longer at the front side than that at the back side. This lopsided growth was attributed to the higher ionic flux induced by electric field at the front side. Accordingly, the nanotube length was further tailored to be comparable at both sides by modulating the electric field. These results are promising to be used in parallel configuration dye-sensitized solar cells, water splitting, and gas sensors, as a result of high surface area produced by the double-sided architecture.

  9. A fabrication method for field emitter array of carbon nanotubes with improved carbon nanotube rooting

    Energy Technology Data Exchange (ETDEWEB)

    Chouhan, V., E-mail: vchouhan@post.kek.jp [School of High Energy Accelerator, The Graduate University for Advanced Studies, Tsukuba 305-0801 (Japan); Noguchi, T. [High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801 (Japan); Kato, S. [School of High Energy Accelerator, The Graduate University for Advanced Studies, Tsukuba 305-0801 (Japan); High Energy Accelerator Research Organization (KEK), Tsukuba 305-0801 (Japan)

    2015-11-30

    We have developed a technique for fabrication of a field emitter array (FEA) of carbon nanotubes (CNTs) to obtain a high emission current along with a high current density. The FEA was prepared with many small equidistant circular emitters of randomly oriented multiwall carbon nanotubes. The fabrication of a FEA substrate followed with deposition of titanium nitride (TiN) film on a tantalum (Ta) substrate and circular titanium (Ti) islands on the TiN coated Ta substrate in a DC magnetron sputtering coater. CNTs were dispersed on the substrate and rooted into the circular Ti islands at a high temperature to prepare an array of circular emitters of CNTs. The TiN film was applied on a Ta substrate to make a reaction barrier between the Ta substrate and CNTs in order to root CNTs only into the Ti islands without a reaction with the Ta substrate at the high temperature. A high emission current of 31.7 mA with an effective current density of 34.5 A/cm{sup 2} was drawn at 6.5 V/μm from a FEA having 130 circular emitters in a diameter of 50 μm and with a pitch of 200 μm. The high emission current was ascribed to the good quality rooting of CNTs into the Ti islands and an edge effect, in which a high emission current was expected from the peripheries of the circular emitters. - Highlights: • We developed a method to fabricate a field emitter array of carbon nanotubes (CNTs). • CNT rooting into array of titanium islands was improved at a high temperature. • Titanium nitride film was used to stop reaction between CNT and tantalum substrate. • Strong edge effect was achieved from an array of small circular emitters of CNTs. • The good quality CNT rooting and the edge effect enhanced an emission current.

  10. Exploring hierarchical FeS2/C composite nanotubes arrays as advanced cathode for lithium ion batteries

    Science.gov (United States)

    Pan, G. X.; Cao, F.; Xia, X. H.; Zhang, Y. J.

    2016-11-01

    Rational construction of advanced FeS2 cathode is one of research hotspots, and of great importance for developing high-performance lithium ion batteries (LIBs). Herein we report a facile hydrolysis-sulfurization method for fabrication of FeS2/C nanotubes arrays with the help of sacrificial Co2(OH)2CO3 nanowires template and glucose carbonization. Self-supported FeS2/C nanotubes consist of interconnected nanoburrs of 5-20 nm, and show hierarchical porous structure. The FeS2/C nanotubes arrays are demonstrated with enhanced cycling life and noticeable high-rate capability with capacities ranging from 735 mAh g-1 at 0.25 C to 482 mAh g-1 at 1.5 C, superior to those FeS2 counterparts in the literature. The composite nanotubes arrays architecture plays positive roles in the electrochemical enhancement due to combined advantages of large electrode-electrolyte contact area, good strain accommodation, improved electrical conductivity, and enhanced structural stability.

  11. Electrochemical DNA biosensor based on the BDD nanograss array electrode.

    Science.gov (United States)

    Jin, Huali; Wei, Min; Wang, Jinshui

    2013-04-10

    The development of DNA biosensor has attracted considerable attention due to their potential applications, including gene analysis, clinical diagnostics, forensic study and more medical applications. Using electroactive daunomycin as an indicator, the hybridization detection was measured by differential pulse voltammetry in this study. Electrochemical DNA biosensor was developed based on the BDD film electrode (fBDD) and BDD nanograss array electrode (nBDD). In comparison with fBDD and AuNPs/CA/fBDD electrode, the lower semicircle diameter of electrochemical impedance spectroscopy obtained on nBDD and AuNPs/CA/nBDD electrode indicated that the presence of nanograss array improved the reactive site, reduced the interfacial resistance, and made the electron transfer easier. Using electroactive daunomycin as an indicator, the hybridization detection was measured by differential pulse voltammetry. The experimental results demonstrated that the prepared AuNPs/CA/nBDD electrode was suitable for DNA hybridization with favorable performance of faster response, higher sensitivity, lower detection limit and satisfactory selectivity, reproducibility and stability.

  12. Formic Acid Electrooxidation by a Platinum Nanotubule Array Electrode

    Directory of Open Access Journals (Sweden)

    Eric Broaddus

    2013-01-01

    Full Text Available One-dimensional metallic nanostructures such as nanowires, rods, and tubes have drawn much attention for electrocatalytic applications due to potential advantages that include fewer diffusion impeding interfaces with polymeric binders, more facile pathways for electron transfer, and more effective exposure of active surface sites. 1D nanostructured electrodes have been fabricated using a variety of methods, typically showing improved current response which has been attributed to improved CO tolerance, enhanced surface activity, and/or improved transport characteristics. A template wetting approach was used to fabricate an array of platinum nanotubules which were examined electrochemically with regard to the electrooxidation of formic acid. Arrays of 100 and 200 nm nanotubules were compared to a traditional platinum black catalyst, all of which were found to have similar surface areas. Peak formic acid oxidation current was observed to be highest for the 100 nm nanotubule array, followed by the 200 nm array and the Pt black; however, CO tolerance of all electrodes was similar, as were the onset potentials of the oxidation and reduction peaks. The higher current response was attributed to enhanced mass transfer in the nanotubule electrodes, likely due to a combination of both the more open nanostructure as well as the lack of a polymeric binder in the catalyst layer.

  13. Real-time imaging of vertically aligned carbon nanotube array growth kinetics

    International Nuclear Information System (INIS)

    Puretzky, A A; Eres, G; Rouleau, C M; Ivanov, I N; Geohegan, D B

    2008-01-01

    In situ time-lapse photography and laser irradiation are applied to understand unusual coordinated growth kinetics of vertically aligned carbon nanotube arrays including pauses in growth, retraction, and local equilibration in length. A model is presented which explains the measured kinetics and determines the conditions for diffusion-limited growth. Laser irradiation of the growing nanotube arrays is first used to prove that the nanotubes grow from catalyst particles at their bases, and then increase their growth rate and terminal lengths

  14. The rational for a mid-scala electrode array.

    Science.gov (United States)

    Boyle, P J

    2016-06-01

    Today increasing numbers of cochlear implant candidates have residual hearing that can be aided and hence is worth trying to preserve. This means that surgical technique and electrode array design must be adapted to minimize trauma. Wide opening of the round window is often preferred to reduce drill related trauma and to avoid pressure spikes during electrode array insertion. A recent meta-analysis suggested that there is no significant correlation between hearing preservation and either insertion depth or scala position. However, a slow insertion speed of at least 30seconds was associated with better hearing preservation. An electrode design is proposed that targets the middle of the scala tympani. This minimizes frictional forces from either lateral or medial wall during insertion and imposes less static pressure on cochlear structures following insertion. The flexibility to insert via the round window requires a 0.7-mm maximum dimension at the proximal end of the array. Micro-anatomical analysis by micro-CT indicated that a 420-degree insertion depth was optimal between cochlear coverage and available space within the scala tympani. Physical measurements showed that mean insertion forces remained below 10mN during insertion. A series of 20 human temporal bone insertions found a mean insertion depth of 400 degrees with no scala dislocations. Six clinical series, in total 94 cases, found postoperative hearing in 81% of cases with a mean loss of 12dB compared to preoperative levels. Speech understanding out to one year post-fitting trended better for a mid-scala design group than for a straight electrode array group; although the differences were not statistically significant. A mid-scala array design appears able to be inserted with minimal trauma, to return a predictable insertion depth across various sizes of cochleae and to support reasonable levels of speech understanding without relying on residual hearing. Copyright © 2016. Published by Elsevier Masson

  15. Modelling clustering of vertically aligned carbon nanotube arrays.

    Science.gov (United States)

    Schaber, Clemens F; Filippov, Alexander E; Heinlein, Thorsten; Schneider, Jörg J; Gorb, Stanislav N

    2015-08-06

    Previous research demonstrated that arrays of vertically aligned carbon nanotubes (VACNTs) exhibit strong frictional properties. Experiments indicated a strong decrease of the friction coefficient from the first to the second sliding cycle in repetitive measurements on the same VACNT spot, but stable values in consecutive cycles. VACNTs form clusters under shear applied during friction tests, and self-organization stabilizes the mechanical properties of the arrays. With increasing load in the range between 300 µN and 4 mN applied normally to the array surface during friction tests the size of the clusters increases, while the coefficient of friction decreases. To better understand the experimentally obtained results, we formulated and numerically studied a minimalistic model, which reproduces the main features of the system with a minimum of adjustable parameters. We calculate the van der Waals forces between the spherical friction probe and bunches of the arrays using the well-known Morse potential function to predict the number of clusters, their size, instantaneous and mean friction forces and the behaviour of the VACNTs during consecutive sliding cycles and at different normal loads. The data obtained by the model calculations coincide very well with the experimental data and can help in adapting VACNT arrays for biomimetic applications.

  16. Glucose biosensor based on glucose oxidase immobilized on unhybridized titanium dioxide nanotube arrays

    International Nuclear Information System (INIS)

    Wang, Wei; Xie, Yibing; Du, Hongxiu; Xia, Chi; Wang, Yong; Tian, Fang

    2014-01-01

    A glucose biosensor has been fabricated by immobilizing glucose oxidase (GOx) on unhybridized titanium dioxide nanotube arrays using an optimized cross-linking technique. The TiO 2 nanotube arrays were synthesized directly on a titanium substrate by anodic oxidation. The structure and morphology of electrode material were characterized by X-ray diffraction and scanning electron microscopy. The electrochemical performances of the glucose biosensor were conducted by cyclic voltammetry and chronoamperometry measurements. It gives a linear response to glucose in the 0.05 to 0.65 mM concentration range, with a correlation coefficient of 0.9981, a sensitivity of 199.6 μA mM −1 cm −2 , and a detection limit as low as 3.8 µM. This glucose biosensor exhibited high selectivity for glucose determination in the presence of ascorbic acid, sucrose and other common interfering substances. This glucose biosensor also performed good reproducibility and long-time storage stability. This optimized cross-linking technique could open a new avenue for other enzyme biosensors fabrication. (author)

  17. Highly efficient biosensors by using well-ordered ZnO/ZnS core/shell nanotube arrays

    Science.gov (United States)

    Tarish, Samar; Xu, Yang; Wang, Zhijie; Mate, Faten; Al-Haddad, Ahmed; Wang, Wenxin; Lei, Yong

    2017-10-01

    We have studied the fabrication of highly efficient glucose sensors using well-ordered heterogeneous ZnO/ZnS core/shell nanotube arrays (CSNAs). The modified electrodes exhibit a superior electrochemical response towards ferrocyanide/ferricyanide and in glucose sensing. Further, the fabricated glucose biosensor exhibited good performance over an acceptable linear range from 2.39 × 10-5 to 2.66 × 10-4 mM, with a sensitivity of 188.34 mA mM-1 cm-2, which is higher than that of the ZnO nanotube array counterpart. A low limit of detection was realized (24 μM), which is good compared with electrodes based on conventional structures. In addition, the enhanced direct electrochemistry of glucose oxidase indicates the fast electron transfer of ZnO/ZnS CSNA electrodes, with a heterogeneous electron transfer rate constant (K s) of 1.69 s-1. The fast electron transfer is attributed to the high conductivity of the modified electrodes. The presented ZnS shell can facilitate the construction of future sensors and enhance the ZnO surface in a biological environment.

  18. WIMP detection and slow ion dynamics in carbon nanotube arrays

    CERN Document Server

    Cavoto, G.; Cocina, F.; Ferretti, J.; Polosa, A.D.

    2016-06-24

    Large arrays of aligned carbon nanotubes (CNTs), open at one end, could be used as target material for the directional detection of weakly interacting dark matter particles (WIMPs). As a result of a WIMP elastic scattering on a CNT, a carbon ion might be injected in the body of the array and propagate through multiple collisions within the lattice. The ion may eventually emerge from the surface with open end CNTs, provided that its longitudinal momentum is large enough to compensate energy losses and its transverse momentum approaches the channeling conditions in a single CNT. Therefore, the angle formed between the WIMP wind apparent orientation and the direction of parallel carbon nanotube axes must be properly chosen. We focus on very low ion recoil kinetic energies, related to low mass WIMPs (~ 10 GeV) where most of the existing experiments have low sensitivity. Relying on some exact results on two-dimensional lattices of circular obstacles, we study the low energy ion motion in the transverse plane with ...

  19. Array of 1- to 2-GHz electrodes for stochastic cooling

    International Nuclear Information System (INIS)

    Voelker, F.; Henderson, T.; Johnson, J.

    1983-03-01

    Described is an array of directional-coupler loop pairs that are to be used as either pickup or kicker electrodes for the frequency range of 1 to 2 GHz. Each coupler pair is a lambda/4 long parallel-plane transmission line that is arranged to be flush with the upper and lower surfaces of a rectangular beam pipe. As pickups, the coupler pairs are used in arrays and are operated at 80 degrees Kelvin for improving the signal-to-noise ratio. The loop output power is added in stripline combiner networks before being fed to a low-noise preamplifier. When the couplers are used as kickers, the combining network serves to split power and distribute it uniformly to each electrode

  20. Direct current injection and thermocapillary flow for purification of aligned arrays of single-walled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Xu; Islam, Ahmad E.; Seabron, Eric; Dunham, Simon N.; Du, Frank; Lin, Jonathan; Wilson, William L.; Rogers, John A., E-mail: jrogers@illinois.edu [Department of Materials Science and Engineering, Frederick Seitz Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Wahab, Muhammad A.; Alam, Muhammad A. [School of Electrical and Computer Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Li, Yuhang [Institute of Solid Mechanics, Beihang University, Beijing 100191 (China); Tomic, Bojan [Department of Electrical Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Huang, Jiyuan [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States); Burns, Branden [Department of Physics, Purdue University, West Lafayette, Indiana 47907 (United States); Song, Jizhou [Department of Engineering Mechanics and Soft Matter Research Center, Zhejiang University, Hangzhou 310027 (China); Huang, Yonggang [Department of Civil and Environmental Engineering, Department of Mechanical Engineering, Center for Engineering and Health, and Skin Disease Research Center, Northwestern University, Evanston, Illinois 60208 (United States)

    2015-04-07

    Aligned arrays of semiconducting single-walled carbon nanotubes (s-SWNTs) represent ideal configurations for use of this class of material in high performance electronics. Development of means for removing the metallic SWNTs (m-SWNTs) in as-grown arrays represents an essential challenge. Here, we introduce a simple scheme that achieves this type of purification using direct, selective current injection through interdigitated electrodes into the m-SWNTs, to allow their complete removal using processes of thermocapillarity and dry etching. Experiments and numerical simulations establish the fundamental aspects that lead to selectivity in this process, thereby setting design rules for optimization. Single-step purification of arrays that include thousands of SWNTs demonstrates the effectiveness and simplicity of the procedures. The result is a practical route to large-area aligned arrays of purely s-SWNTs with low-cost experimental setups.

  1. Direct current injection and thermocapillary flow for purification of aligned arrays of single-walled carbon nanotubes

    International Nuclear Information System (INIS)

    Xie, Xu; Islam, Ahmad E.; Seabron, Eric; Dunham, Simon N.; Du, Frank; Lin, Jonathan; Wilson, William L.; Rogers, John A.; Wahab, Muhammad A.; Alam, Muhammad A.; Li, Yuhang; Tomic, Bojan; Huang, Jiyuan; Burns, Branden; Song, Jizhou; Huang, Yonggang

    2015-01-01

    Aligned arrays of semiconducting single-walled carbon nanotubes (s-SWNTs) represent ideal configurations for use of this class of material in high performance electronics. Development of means for removing the metallic SWNTs (m-SWNTs) in as-grown arrays represents an essential challenge. Here, we introduce a simple scheme that achieves this type of purification using direct, selective current injection through interdigitated electrodes into the m-SWNTs, to allow their complete removal using processes of thermocapillarity and dry etching. Experiments and numerical simulations establish the fundamental aspects that lead to selectivity in this process, thereby setting design rules for optimization. Single-step purification of arrays that include thousands of SWNTs demonstrates the effectiveness and simplicity of the procedures. The result is a practical route to large-area aligned arrays of purely s-SWNTs with low-cost experimental setups

  2. 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.)

  3. Solution-processed single-wall carbon nanotube transistor arrays for wearable display backplanes

    Directory of Open Access Journals (Sweden)

    Byeong-Cheol Kang

    2018-01-01

    Full Text Available In this paper, we demonstrate solution-processed single-wall carbon nanotube thin-film transistor (SWCNT-TFT arrays with polymeric gate dielectrics on the polymeric substrates for wearable display backplanes, which can be directly attached to the human body. The optimized SWCNT-TFTs without any buffer layer on flexible substrates exhibit a linear field-effect mobility of 1.5cm2/V-s and a threshold voltage of around 0V. The statistical plot of the key device metrics extracted from 35 SWCNT-TFTs which were fabricated in different batches at different times conclusively support that we successfully demonstrated high-performance solution-processed SWCNT-TFT arrays which demand excellent uniformity in the device performance. We also investigate the operational stability of wearable SWCNT-TFT arrays against an applied strain of up to 40%, which is the essential for a harsh degree of strain on human body. We believe that the demonstration of flexible SWCNT-TFT arrays which were fabricated by all solution-process except the deposition of metal electrodes at process temperature below 130oC can open up new routes for wearable display backplanes.

  4. Physicochemical characteristics and droplet impact dynamics of superhydrophobic carbon nanotube arrays.

    Science.gov (United States)

    Aria, Adrianus I; Gharib, Morteza

    2014-06-17

    The physicochemical and droplet impact dynamics of superhydrophobic carbon nanotube arrays are investigated. These superhydrophobic arrays are fabricated simply by exposing the as-grown carbon nanotube arrays to a vacuum annealing treatment at a moderate temperature. This treatment, which allows a significant removal of oxygen adsorbates, leads to a dramatic change in wettability of the arrays, from mildly hydrophobic to superhydrophobic. Such change in wettability is also accompanied by a substantial change in surface charge and electrochemical properties. Here, the droplet impact dynamics are characterized in terms of critical Weber number, coefficient of restitution, spreading factor, and contact time. Based on these characteristics, it is found that superhydrophobic carbon nanotube arrays are among the best water-repellent surfaces ever reported. The results presented herein may pave a way for the utilization of superhydrophobic carbon nanotube arrays in numerous industrial and practical applications, including inkjet printing, direct injection engines, steam turbines, and microelectronic fabrication.

  5. Lithium storage study on MoO3-grafted TiO2 nanotube arrays

    Directory of Open Access Journals (Sweden)

    Tauseef Anwar

    2016-03-01

    Full Text Available Abstract Titanium dioxide nanotube arrays (TNAs were fabricated via anodic ionization. Porous MoO3 was grafted on TNAs with the help of hydrothermal method. Scanning electron microscopy and X-ray powder diffraction was utilized for the confirmation of one dimensional morphology and phase identification. The porous MoO3 nanoflake-grafted TNAs (MoO3/TNAs electrode was used as anode material in lithium ion battery (LIB and it was found that the areal specific capacity of MoO3/TNAs (~797 µAh cm−2 was three times higher than those of anatase TNAs (~287 µAh cm−2 and porous MoO3 (~234 µAh cm−2 at 50 µA cm−2.

  6. Bifacial dye-sensitized solar cells based on vertically oriented TiO2 nanotube arrays

    International Nuclear Information System (INIS)

    Liu Zhaoyue; Misra, Mano

    2010-01-01

    In this work we describe a novel bifacial design concept for dye-sensitized solar cells (DSCs). Bifacial DSCs are fabricated with ruthenium complex chemisorbed double-sided TiO 2 nanotube arrays on a Ti metal substrate, in combination with two electron-collecting counter electrodes. Our investigation shows that the present bifacial DSCs have similar conversion efficiencies when illuminated from either their front or rear side, and a summated output power when illuminated on both sides. Furthermore, this type of bifacial DSC is also able to summate the output power of each side when working at an 'unsymmetrical' mode, in which much different output powers are generated by the front and rear sides. Therefore, this bifacial design concept exhibits a promising potential to reduce the cost of solar electricity when DSCs are operated at a location where a high albedo radiation is available.

  7. Thin-film electroencephalographic electrodes using multi-walled carbon nanotubes are effective for neurosurgery.

    Science.gov (United States)

    Awara, Kousuke; Kitai, Ryuhei; Isozaki, Makoto; Neishi, Hiroyuki; Kikuta, Kenichiro; Fushisato, Naoki; Kawamoto, Akira

    2014-12-15

    Intraoperative morphological and functional monitoring is essential for safe neurosurgery. Functional monitoring is based on electroencephalography (EEG), which uses silver electrodes. However, these electrodes generate metal artifacts as silver blocks X-rays, creating white radial lines on computed tomography (CT) images during surgery. Thick electrodes interfere with surgical procedures. Thus, thinner and lighter electrodes are ideal for intraoperative use. The authors developed thin brain electrodes using carbon nanotubes that were formed into thin sheets and connected to electrical wires. The nanotube sheets were soft and fitted the curve of the head very well. When attached to the head using paste, the impedance of the newly developed electrodes was 5 kΩ or lower, which was similar to that of conventional metal electrodes. These electrodes can be used in combination with intraoperative CT, magnetic resonance imaging (MRI), or cerebral angiography. Somatosensory-evoked potentials, auditory brainstem responses, and visually evoked potentials were clearly identified in ten volunteers. The electrodes, without any artifacts that distort images, did not interfere with X-rays, CT, or MR images. They also did not cause skin damage. Carbon nanotube electrodes may be ideal for neurosurgery.

  8. Embedded arrays of vertically aligned carbon nanotube carpets and methods for making them

    Science.gov (United States)

    Kim, Myung Jong; Nicholas, Nolan Walker; Kittrell, W. Carter; Schmidt, Howard K.

    2015-06-30

    According to some embodiments, the present invention provides a system and method for supporting a carbon nanotube array that involve an entangled carbon nanotube mat integral with the array, where the mat is embedded in an embedding material. The embedding material may be depositable on a carbon nanotube. A depositable material may be metallic or nonmetallic. The embedding material may be an adhesive material. The adhesive material may optionally be mixed with a metal powder. The embedding material may be supported by a substrate or self-supportive. The embedding material may be conductive or nonconductive. The system and method provide superior mechanical and, when applicable, electrical, contact between the carbon nanotubes in the array and the embedding material. The optional use of a conductive material for the embedding material provides a mechanism useful for integration of carbon nanotube arrays into electronic devices.

  9. Anodic Fabrication of Ti-Ni-O Nanotube Arrays on Shape Memory Alloy

    Directory of Open Access Journals (Sweden)

    Qiang Liu

    2014-04-01

    Full Text Available Surface modification with oxide nanostructures is one of the efficient ways to improve physical or biomedical properties of shape memory alloys. This work reports a fabrication of highly ordered Ti-Ni-O nanotube arrays on Ti-Ni alloy substrates through pulse anodization in glycerol-based electrolytes. The effects of anodization parameters and the annealing process on the microstructures and surface morphology of Ti-Ni-O were studied using scanning electron microscope and Raman spectroscopy. The electrolyte type greatly affected the formation of nanotube arrays. A formation of anatase phase was found with the Ti-Ni-O nanotube arrays annealed at 450 °C. The oxide nanotubes could be crystallized to rutile phase after annealing treatment at 650 °C. The Ti-Ni-O nanotube arrays demonstrated an excellent thermal stability by keeping their nanotubular structures up to 650 °C.

  10. Metal-electrode-free Window-like Organic Solar Cells with p-Doped Carbon Nanotube Thin-film Electrodes

    Science.gov (United States)

    Jeon, Il; Delacou, Clement; Kaskela, Antti; Kauppinen, Esko I.; Maruyama, Shigeo; Matsuo, Yutaka

    2016-08-01

    Organic solar cells are flexible and inexpensive, and expected to have a wide range of applications. Many transparent organic solar cells have been reported and their success hinges on full transparency and high power conversion efficiency. Recently, carbon nanotubes and graphene, which meet these criteria, have been used in transparent conductive electrodes. However, their use in top electrodes has been limited by mechanical difficulties in fabrication and doping. Here, expensive metal top electrodes were replaced with high-performance, easy-to-transfer, aerosol-synthesized carbon nanotubes to produce transparent organic solar cells. The carbon nanotubes were p-doped by two new methods: HNO3 doping via ‘sandwich transfer’, and MoOx thermal doping via ‘bridge transfer’. Although both of the doping methods improved the performance of the carbon nanotubes and the photovoltaic performance of devices, sandwich transfer, which gave a 4.1% power conversion efficiency, was slightly more effective than bridge transfer, which produced a power conversion efficiency of 3.4%. Applying a thinner carbon nanotube film with 90% transparency decreased the efficiency to 3.7%, which was still high. Overall, the transparent solar cells had an efficiency of around 50% that of non-transparent metal-based solar cells (7.8%).

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

    KAUST Repository

    Tripathi, Bijay Prakash; Schieda, Mauricio; Shahi, Vinod Kumar; Nunes, Suzana Pereira

    2011-01-01

    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.

  12. 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.

  13. Porosimetry and packing morphology of vertically-aligned carbon nanotube arrays via impedance spectroscopy.

    Science.gov (United States)

    Mutha, Heena K; Lu, Yuan; Stein, Itai; Cho, H Jeremy; Suss, Matthew; Laoui, Tahar; Thompson, Carl; Wardle, Brian; Wang, Evelyn

    2016-12-13

    Vertically aligned one-dimensional nanostructure arrays are promising in many applications such as electrochemical systems, solar cells, and electronics, taking advantage of high surface area per unit volume, nanometer length scale packing, and alignment leading to high conductivity. However, many devices need to optimize arrays for device performance by selecting an appropriate morphology. Developing a simple, non-invasive tool for understanding the role of pore volume distribution and interspacing would aid in the optimization of nanostructure morphologies in electrodes. In this work, we combined electrochemical impedance spectroscopy (EIS) with capacitance measurements and porous electrode theory to conduct in situ porosimetry of vertically-aligned carbon nanotubes (VA-CNTs) non-destructively. We utilized the EIS measurements with a pore size distribution model to quantify the average and dispersion of inter-CNT spacing (Γ), stochastically, in carpets that were mechanically densified from 1.7 × 1010 tubes/cm2 to 4.5 × 1011 tubes/cm2. Our analysis predicts that the inter-CNT spacing ranges from over 100 ± 50 nm in sparse carpets to sub 10 ± 5 nm in packed carpets. Our results suggest that waviness of CNTs leads to variations in the inter-CNT spacing, which can be significant in sparse carpets. This methodology can be used to predict the performance of many nanostructured devices, including supercapacitors, batteries, solar cells, and semiconductor electronics. Copyright 2016 IOP Publishing Ltd.

  14. Micromachined three-dimensional electrode arrays for transcutaneous nerve tracking

    Science.gov (United States)

    Rajaraman, Swaminathan; Bragg, Julian A.; Ross, James D.; Allen, Mark G.

    2011-08-01

    We report the development of metal transfer micromolded (MTM) three-dimensional microelectrode arrays (3D MEAs) for a transcutaneous nerve tracking application. The measurements of electrode-skin-electrode impedance (ESEI), electromyography (EMG) and nerve conduction utilizing these minimally invasive 3D MEAs are demonstrated in this paper. The 3D MEAs used in these measurements consist of a metalized micro-tower array that can penetrate the outer layers of the skin in a painless fashion and are fabricated using MTM technology. Two techniques, an inclined UV lithography approach and a double-side exposure of thick negative tone resist, have been developed to fabricate the 3D MEA master structure. The MEAs themselves are fabricated from the master structure utilizing micromolding techniques. Metal patterns are transferred during the micromolding process, thereby ensuring reduced process steps compared to traditional silicon-based approaches. These 3D MEAs have been packaged utilizing biocompatible Kapton® substrates. ESEI measurements have been carried out on test human subjects with standard commercial wet electrodes as a reference. The 3D MEAs demonstrate an order of magnitude lower ESEI (normalized to area) compared to wet electrodes for an area that is 12.56 times smaller. This compares well with other demonstrated approaches in literature. For a nerve tracking demonstration, we have chosen EMG and nerve conduction measurements on test human subjects. The 3D MEAs show 100% improvement in signal power and SNR/√area as compared to standard electrodes. They also demonstrate larger amplitude signals and faster rise times during nerve conduction measurements. We believe that this microfabrication and packaging approach scales well to large-area, high-density arrays required for applications like nerve tracking. This development will increase the stimulation and recording fidelity of skin surface electrodes, while increasing their spatial resolution by an order of

  15. A three-dimensional microelectrode array composed of vertically aligned ultra-dense carbon nanotube networks

    Science.gov (United States)

    Nick, C.; Yadav, S.; Joshi, R.; Schneider, J. J.; Thielemann, C.

    2015-07-01

    Electrodes based on carbon nanotubes are a promising approach to manufacture highly sensitive sensors with a low limit of signal detection and a high signal-to-noise ratio. This is achieved by dramatically increasing the electrochemical active surface area without increasing the overall geometrical dimensions. Typically, carbon nanotube electrodes are nearly planar and composed of randomly distributed carbon nanotube networks having a limited surface gain for a specific geometrical surface area. To overcome this limitation, we have introduced vertically aligned carbon nanotube (VACNT) networks as electrodes, which are arranged in a microelectrode pattern of 60 single electrodes. Each microelectrode features a very high aspect ratio of more than 300 and thus a dramatically increased surface area. These microelectrodes composed of VACNT networks display dramatically decreased impedance over the entire frequency range compared to planar microelectrodes caused by the enormous capacity increase. This is experimentally verified by electrochemical impedance spectroscopy and cyclic voltammetry.

  16. Fabrication of an artificial nanosucker device with a large area nanotube array of metallic glass.

    Science.gov (United States)

    Chen, Wei-Ting; Manivannan, Karthikeyan; Yu, Chia-Chi; Chu, Jinn P; Chen, Jem-Kun

    2018-01-18

    The concurrent attachment and detachment movements of geckos on virtually any type of surface via their foot pads have inspired us to develop a thermal device with numerous arrangements of a multi-layer thin film together with electrodes that can help modify the temperature of the surface via application of a voltage. A sequential fabrication process was employed on a large-scale integration to generate well-defined contact hole arrays of photoresist for use as templates on the electrode-based device. The photoresist templates were then subjected to sputter deposition of the metallic glass Zr 55 Cu 30 Al 10 Ni 5 . Consequently, a metallic glass nanotube (MGNT) array having a nominal wall thickness of 100 nm was obtained after removal of the photoresist template. When a water droplet was placed on the MGNT array, close nanochambers of metallic glass were formed. By applying voltage, the surface was heated to increase the pressure inside the nanochambers; this generated an expanding force that raised the droplet; thus, the static water contact angle (SWCA) was increased. In contrast, a sucking force was generated during surface cooling, which decreased the SWCA. Our fabrication strategy exploits the MGNT array surface as nanosuckers, which can mimic the climbing aptitude of geckos as they attach to (>10 N m -2 ) and detach from (0.26 N m -2 ) surfaces at 0.5 and 3 V of applied voltage, respectively. Thus, the climbing aptitude of geckos can be mimicked by employing the processing strategy presented herein for the development of artificial foot pads.

  17. Micromachined three-dimensional electrode arrays for transcutaneous nerve tracking

    International Nuclear Information System (INIS)

    Rajaraman, Swaminathan; Allen, Mark G; Bragg, Julian A; Ross, James D

    2011-01-01

    We report the development of metal transfer micromolded (MTM) three-dimensional microelectrode arrays (3D MEAs) for a transcutaneous nerve tracking application. The measurements of electrode–skin–electrode impedance (ESEI), electromyography (EMG) and nerve conduction utilizing these minimally invasive 3D MEAs are demonstrated in this paper. The 3D MEAs used in these measurements consist of a metalized micro-tower array that can penetrate the outer layers of the skin in a painless fashion and are fabricated using MTM technology. Two techniques, an inclined UV lithography approach and a double-side exposure of thick negative tone resist, have been developed to fabricate the 3D MEA master structure. The MEAs themselves are fabricated from the master structure utilizing micromolding techniques. Metal patterns are transferred during the micromolding process, thereby ensuring reduced process steps compared to traditional silicon-based approaches. These 3D MEAs have been packaged utilizing biocompatible Kapton® substrates. ESEI measurements have been carried out on test human subjects with standard commercial wet electrodes as a reference. The 3D MEAs demonstrate an order of magnitude lower ESEI (normalized to area) compared to wet electrodes for an area that is 12.56 times smaller. This compares well with other demonstrated approaches in literature. For a nerve tracking demonstration, we have chosen EMG and nerve conduction measurements on test human subjects. The 3D MEAs show 100% improvement in signal power and SNR/√area as compared to standard electrodes. They also demonstrate larger amplitude signals and faster rise times during nerve conduction measurements. We believe that this microfabrication and packaging approach scales well to large-area, high-density arrays required for applications like nerve tracking. This development will increase the stimulation and recording fidelity of skin surface electrodes, while increasing their spatial resolution by an order

  18. Disposable pencil graphite electrode modified with peptide nanotubes for Vitamin B{sub 12} analysis

    Energy Technology Data Exchange (ETDEWEB)

    Pala, Betül Bozdoğan [Nanotechnology and Nanomedicine Division, Institute of Science, Hacettepe University, 06800 Ankara (Turkey); Vural, Tayfun [Department of Chemistry, Faculty of Science, Hacettepe University, 06800 Beytepe, Ankara (Turkey); Kuralay, Filiz [Department of Chemistry, Faculty of Science and Arts, Ordu University, 52200 Ordu (Turkey); Çırak, Tamer [Nanotechnology and Nanomedicine Division, Institute of Science, Hacettepe University, 06800 Ankara (Turkey); Bolat, Gülçin; Abacı, Serdar [Department of Chemistry, Faculty of Science, Hacettepe University, 06800 Beytepe, Ankara (Turkey); Denkbaş, Emir Baki, E-mail: denkbas@hacettepe.edu.tr [Department of Chemistry, Faculty of Science, Hacettepe University, 06800 Beytepe, Ankara (Turkey)

    2014-06-01

    In this study, peptide nanostructures from diphenylalanine were synthesized in various solvents with various polarities and characterized with Scanning Electron Microscopy (SEM) and Powder X-ray Diffraction (PXRD) techniques. Formation of peptide nanofibrils, nanovesicles, nanoribbons, and nanotubes was observed in different solvent mediums. In order to investigate the effects of peptide nanotubes (PNT) on electrochemical behavior of disposable pencil graphite electrodes (PGE), electrode surfaces were modified with fabricated peptide nanotubes. Electrochemical activity of the pencil graphite electrode was increased with the deposition of PNTs on the surface. The effects of the solvent type, the peptide nanotube concentration, and the passive adsorption time of peptide nanotubes on pencil graphite electrode were studied. For further electrochemical studies, electrodes were modified for 30 min by immobilizing PNTs, which were prepared in water at 6 mg/mL concentration. Vitamin B{sub 12} analyses were performed by the Square Wave (SW) voltammetry method using modified PGEs. The obtained data showed linearity over the range of 0.2 μM and 9.50 μM Vitamin B{sub 12} concentration with high sensitivity. Results showed that PNT modified PGEs were highly simple, fast, cost effective, and feasible for the electro-analytical determination of Vitamin B{sub 12} in real samples.

  19. Disposable pencil graphite electrode modified with peptide nanotubes for Vitamin B12 analysis

    International Nuclear Information System (INIS)

    Pala, Betül Bozdoğan; Vural, Tayfun; Kuralay, Filiz; Çırak, Tamer; Bolat, Gülçin; Abacı, Serdar; Denkbaş, Emir Baki

    2014-01-01

    In this study, peptide nanostructures from diphenylalanine were synthesized in various solvents with various polarities and characterized with Scanning Electron Microscopy (SEM) and Powder X-ray Diffraction (PXRD) techniques. Formation of peptide nanofibrils, nanovesicles, nanoribbons, and nanotubes was observed in different solvent mediums. In order to investigate the effects of peptide nanotubes (PNT) on electrochemical behavior of disposable pencil graphite electrodes (PGE), electrode surfaces were modified with fabricated peptide nanotubes. Electrochemical activity of the pencil graphite electrode was increased with the deposition of PNTs on the surface. The effects of the solvent type, the peptide nanotube concentration, and the passive adsorption time of peptide nanotubes on pencil graphite electrode were studied. For further electrochemical studies, electrodes were modified for 30 min by immobilizing PNTs, which were prepared in water at 6 mg/mL concentration. Vitamin B 12 analyses were performed by the Square Wave (SW) voltammetry method using modified PGEs. The obtained data showed linearity over the range of 0.2 μM and 9.50 μM Vitamin B 12 concentration with high sensitivity. Results showed that PNT modified PGEs were highly simple, fast, cost effective, and feasible for the electro-analytical determination of Vitamin B 12 in real samples.

  20. Thin randomly aligned hierarchical carbon nanotube arrays as ultrablack metamaterials

    Science.gov (United States)

    De Nicola, Francesco; Hines, Peter; De Crescenzi, Maurizio; Motta, Nunzio

    2017-07-01

    Ultrablack metamaterials are artificial materials able to harvest all the incident light regardless of wavelength, angle, or polarization. Here, we show the ultrablack properties of randomly aligned hierarchical carbon nanotube arrays with thicknesses below 200 nm. The thin coatings are realized by solution processing and dry-transfer deposition on different substrates. The hierarchical surface morphology of the coatings is biomimetic and provides a large effective area that improves the film optical absorption. Also, such a morphology is responsible for the moth-eye effect, which leads to the omnidirectional and polarization-independent suppression of optical reflection. The films exhibit an emissivity up to 99.36% typical of an ideal black body, resulting in the thinnest ultrablack metamaterial ever reported. Such a material may be exploited for thermal, optical, and optoelectronic devices such as heat sinks, optical shields, solar cells, light and thermal sensors, and light-emitting diodes.

  1. Polymeric Electrolyte Membrane Photoelectrochemical (PEM-PEC Cell with a Web of Titania Nanotube Arrays as Photoanode and Gaseous Reactants

    Directory of Open Access Journals (Sweden)

    Tsampas M.N.

    2017-01-01

    Photoanodes of titania nanotube arrays, TNTAs, were developed, for the first time, on a Ti-web of microfiber substrates, by electrochemical anodization. The performance of TNTAs/Ti-web photoanodes were evaluated in both gaseous and liquid reactants. Due to the presence of reliable reference electrode in gas phase direct comparison of the results was possible. Gas phase operation with He or Air as carrier gases and only 2.5% of water content exhibits very promising photoefficiency in comparison with conventional PEC cells.

  2. Graphene-carbon nanotube hybrid materials and use as electrodes

    Science.gov (United States)

    Tour, James M.; Zhu, Yu; Li, Lei; Yan, Zheng; Lin, Jian

    2016-09-27

    Provided are methods of making graphene-carbon nanotube hybrid materials. Such methods generally include: (1) associating a graphene film with a substrate; (2) applying a catalyst and a carbon source to the graphene film; and (3) growing carbon nanotubes on the graphene film. The grown carbon nanotubes become covalently linked to the graphene film through carbon-carbon bonds that are located at one or more junctions between the carbon nanotubes and the graphene film. In addition, the grown carbon nanotubes are in ohmic contact with the graphene film through the carbon-carbon bonds at the one or more junctions. The one or more junctions may include seven-membered carbon rings. Also provided are the formed graphene-carbon nanotube hybrid materials.

  3. Conformally encapsulated multi-electrode arrays with seamless insulation

    Energy Technology Data Exchange (ETDEWEB)

    Tabada, Phillipe J.; Shah, Kedar G.; Tolosa, Vanessa; Pannu, Satinderall S.; Tooker, Angela; Delima, Terri; Sheth, Heeral; Felix, Sarah

    2016-11-22

    Thin-film multi-electrode arrays (MEA) having one or more electrically conductive beams conformally encapsulated in a seamless block of electrically insulating material, and methods of fabricating such MEAs using reproducible, microfabrication processes. One or more electrically conductive traces are formed on scaffold material that is subsequently removed to suspend the traces over a substrate by support portions of the trace beam in contact with the substrate. By encapsulating the suspended traces, either individually or together, with a single continuous layer of an electrically insulating material, a seamless block of electrically insulating material is formed that conforms to the shape of the trace beam structure, including any trace backings which provide suspension support. Electrical contacts, electrodes, or leads of the traces are exposed from the encapsulated trace beam structure by removing the substrate.

  4. Exploring aligned-carbon-nanotubes@polyaniline arrays on household Al as supercapacitors.

    Science.gov (United States)

    Huang, Fan; Lou, Fengliu; Chen, De

    2012-05-01

    Herein, we demonstrate a new approach towards the construction of supercapacitors consisting of carbon nanotubes (CNTs) and conducting polymers (ECPs) with high specific power, high specific energy, and stable cycling performance through a 3D design of a thin film of polyaniline (PANI) on an aligned small carbon nanotube (ACNT) array on household Al foils. The thin-film strategy is used to fully exploit the specific capacitance of PANI, and obtain regular pores, strong interaction between PANI and CNTs, and reduced electrical resistance for the electrodes. A facile process is developed to fabricate a highly flexible supercapacitor using this binder-free composite on household Al foil as the current collector. It exhibits high specific energy of 18.9 Wh kg(-1) , high maximum specific power of 11.3 kW kg(-1) of the active material in an aqueous electrolyte at 1.0 A g(-1) , and excellent rate performance and cycling stability. A high specific energy of 72.4 Wh kg(-1) , a high maximum specific power of 24.9 kW kg(-1) , and a good cycling performance of the active material are obtained in an organic electrolyte. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Au Nanoparticles Decorated TiO2 Nanotube Arrays as a Recyclable Sensor for Photoenhanced Electrochemical Detection of Bisphenol A.

    Science.gov (United States)

    Hu, Liangsheng; Fong, Chi-Chun; Zhang, Xuming; Chan, Leo Lai; Lam, Paul K S; Chu, Paul K; Wong, Kwok-Yin; Yang, Mengsu

    2016-04-19

    A photorefreshable and photoenhanced electrochemical sensing platform for bisphenol A (BPA) detection based on Au nanoparticles (NPs) decorated carbon doped TiO2 nanotube arrays (TiO2/Au NTAs) is described. The TiO2/Au NTAs were prepared by quick annealing of anodized nanotubes in argon, followed by controllable electrodeposition of Au NPs. The decoration of Au NPs not only improved photoelectrochemical behavior but also enhanced electrocatalytic activities of the resulted hybrid NTAs. Meanwhile, the high photocatalytic activity of the NTAs allowed the electrode to be readily renewed without damaging the microstructures and surface states after a short UV treatment. The electrochemical detection of BPA on TiO2/Au NTAs electrode was significantly improved under UV irradiation as the electrode could provide fresh reaction surface continuously and the further increased photocurrent resulting from the improved separation efficiency of the photogenerated electron-hole pairs derived from the consumption of holes by BPA. The results showed that the refreshable TiO2/Au NTAs electrode is a promising sensor for long-term BPA monitoring with the detection limit (S/N = 3) of 6.2 nM and the sensitivity of 2.8 μA·μM(-1)·cm(-2).

  6. Carbon nanotubes functionalized by salts containing stereogenic heteroatoms as electrodes in their battery cells

    OpenAIRE

    Zdanowska Sandra; Pyzalska Magdalena; Drabowicz Józef; Kulawik Damian; Pavlyuk Volodymyr; Girek Tomasz; Ciesielski Wojciech

    2016-01-01

    This paper concentrates on electrochemical properties of groups of multi-walled carbon nanotubes (MWCNT) functionalized with substituents containing a stereogenic heteroatom bonded covalently to the surface of the carbon nanotube. This system was tested in Swagelok-type cells. The cells comprised a system (functionalized CNT with salts containing S and P atoms) with a working electrode, microfiber separators soaked with electrolyte solution, and a lithium foil counter/reference (commercial Li...

  7. Preparation and elementary research on electrocatalytic hydrogen evolution of highly ordered titanium dioxide nanotube arrays

    International Nuclear Information System (INIS)

    Wu Qinglong; Liao Junsheng; Bai Yun

    2010-01-01

    Well ordered and uniform titanium dioxide nanotube arrays were fabricated by anodiaing process from a bath containing 1% NaF, 1mol/L Na 2 SO 4 , 0.5 mol/L H 2 SO 4 at room temperature. Surface morphology of titanium dioxide nanotube arrays were observed with SEM. The formation process of titanium dioxide nanotube arrays was suggested by current-time transient. Its catalytic hydrogen evolution behavior was studied by electrochemical measurements in a 5%(mass fraction) H 2 SO 4 solution. The results showed that the titanium dioxide nanotube arrays on titanium had better hydrogen evolution activity and trace palladium lead to the maximum electrocatalytic activity of hydrogen production. (authors)

  8. Optimizing the fabrication of carbon nanotube electrode for effective capacitive deionization via electrophoretic deposition strategy

    Directory of Open Access Journals (Sweden)

    Simeng Zhang

    2018-04-01

    Full Text Available In order to obtain superior electrode performances in capacitive deionization (CDI, the electrophoretic deposition (EPD was introduced as a novel strategy for the fabrication of carbon nanotube (CNT electrode. Preparation parameters, including the concentration of slurry components, deposition time and electric field intensity, were mainly investigated and optimized in terms of electrochemical characteristic and desalination performance of the deposited CNT electrode. The SEM image shows that the CNT material was deposited homogeneously on the current collector and a non-crack surface of the electrode was obtained. An optimal preparation condition of the deposited CNT electrode was obtained and specified as the Al (NO33 M concentration of 1.3 × 10−2 mol/L, the deposition time of 30 min and the electric field intensity of 15 V/cm. The obtained electrode performs an increasing specific mass capacitance of 33.36 F/g and specific adsorption capacity of 23.93 mg/g, which are 1.62 and 1.85 times those of the coated electrode respectively. The good performance of the deposited CNT electrode indicates the promising application of the EPD methodology in subsequent research and fabrication of the CDI electrodes for CDI process. Keywords: Carbon nanotube, Water treatment, Desalination, Capacitive deionization, Electrode fabrication, Electrophoretic deposition

  9. Performance of dye-sensitized solar cells with various carbon nanotube counter electrodes

    International Nuclear Information System (INIS)

    Zhang, D.; Li, X.; Chen, S.; Sun, Z.; Huang, S.; Yin, X.J.

    2011-01-01

    Double-wall carbon nanotubes (DWCNTs), single-wall carbon nanotubes (SWCNTs), and multi-wall carbon nanotubes (MWCNTs) were investigated as an alternative for platinum in counter-electrodes for dye-sensitized solar cells. The counter-electrodes were prepared on fluorine-doped tin oxide glass substrates by the screen printing technique from pastes of carbon nanotubes and organic binder. The solar cells were assembled from carbon nanotubes counter-electrodes and screen printed anodes made from titanium dioxide. The cells produced with DWCNTs, SWCNTs or MWCNTs have overall conversion efficiencies of 8.0%, 7.6% and 7.1%, respectively. Electrochemical impedance spectroscopy measurements revealed that DWCNTs displayed the highest catalytic activity for the reduction of tri-iodide ions. The large surface area and superior chemical stability of the DWCNTs facilitated the electron-transfer kinetics at the interface between counter-electrode and electrolyte and yielded the lowest transfer resistance, thereby improving the photovoltaic activity. A short-term stability test at moderate conditions confirmed the robustness of solar cells based on the use of DWCNTs, SWCNTs or MWCNTs. (author)

  10. Poly(3,4-ethylenedioxythiophene) nanotubes as electrode materials for a high-powered supercapacitor

    International Nuclear Information System (INIS)

    Liu Ran; Cho, Seung Il; Lee, Sang Bok

    2008-01-01

    We report the fast charging/discharging capability of poly(3,4-ethylenedioxythiophene) (PEDOT) nanotubes during the redox process and their potential application to a high-powered supercapacitor. PEDOT nanotubes were electrochemically synthesized in a porous alumina membrane, and their structures were characterized using electron microscopes. Cyclic voltammetry was used to characterize the specific capacitance of the PEDOT nanotubes at various scan rates. A type I supercapacitor (two symmetric electrodes) based on PEDOT nanotube electrodes was fabricated, and its energy density and power density were evaluated by galvanostatic charge/discharge cycles at various current densities. We show that the PEDOT-nanotube-based supercapacitor can achieve a high power density of 25 kW kg -1 while maintaining 80% energy density (5.6 W h kg -1 ). This high power capability is attributed to the fast charge/discharge of nanotubular structures: hollow nanotubes allow counter-ions to readily penetrate into the polymer and access their internal surfaces, while the thin wall provides a short diffusion distance to facilitate the ion transport. Impedance spectroscopy shows that nanotubes have much lower diffusional resistance to charging ions than solid nanowires shielded by an alumina template, providing supporting information for the high charging/discharging efficiency of nanotubular structures

  11. Photoelectrocatalytic properties of Ag nanoparticles loaded TiO2 nanotube arrays prepared by pulse current deposition

    International Nuclear Information System (INIS)

    Xie Kunpeng; Sun Lan; Wang Chenglin; Lai Yuekun; Wang Mengye; Chen Hongbo; Lin Changjian

    2010-01-01

    A pulse current deposition technique was adopted to construct highly dispersed Ag nanoparticles on TiO 2 nanotube arrays which were prepared by the electrochemical anodization. The morphology, crystallinity, elemental composition, and UV-vis absorption of Ag/TiO 2 nanotube arrays were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and diffuse reflectance spectra (DRS). In particular, the photoelectrochemical properties and photoelectrocatalytic activity under UV light irradiation and the photocatalytic activity under visible light irradiation for newly synthesized Ag/TiO 2 nanotube arrays were investigated. The maximum incident photon to charge carrier efficiency (IPCE) value of Ag/TiO 2 nanotube arrays was 51%, much higher than that of pure TiO 2 nanotube arrays. Ag/TiO 2 nanotube arrays exhibited higher photocatalytic activities than the pure TiO 2 nanotube arrays under both UV and visible light irradiation. The photoelectrocatalytic activity of Ag/TiO 2 nanotube arrays under UV light irradiation was 1.6-fold enhancement compared with pure TiO 2 nanotube arrays. This approach can be used in synthesizing various metal-loaded nanotube arrays materials.

  12. Preparation of FeS2 nanotube arrays based on layer-by-layer assembly and their photoelectrochemical properties

    International Nuclear Information System (INIS)

    Wang, Mudan; Xue, Dongpeng; Qin, Haiying; Zhang, Lei; Ling, Guoping; Liu, Jiabin; Fang, Youtong; Meng, Liang

    2016-01-01

    Graphical abstract: - Highlights: • Amorphous Fe 2 O 3 nanotube arrays are prepared via layer-by-layer assembly. • Pyrite FeS 2 nanotube arrays are obtained by sulfurizing Fe 2 O 3 nanotube arrays. • Various electrochemical properties are characterized. • A comparison between FeS 2 nanotube and nanoparticle films is conducted. • Nanotube arrays show enhanced corrosion resistance and photoresponse. - Abstract: Well-aligned one-dimensional iron pyrite FeS 2 nanotube arrays have been fabricated via layer-by-layer assembly technique on ZnO nanorod arrays in combination with subsequent sulfurization. The as-prepared products were confirmed to be pure phase pyrite FeS 2 with Fe/S ratio approaching 1/2. Typical nanotube structure was observed for the FeS 2 with average outer diameter of 150 ± 20 nm and wall thickness of 50 ± 5 nm. Comparisons of photoelectrochemical properties between FeS 2 nanotubes and FeS 2 nanoparticles were conducted. Tafel polarization curves and electrochemical impedance spectroscopy indicate that FeS 2 nanotubes possess high corrosion resistance and electrochemical stability. The J–V curves show that the photocurrent at 1.0 V for FeS 2 nanotubes is more than five times larger than that of FeS 2 nanoparticles, indicating enhanced photoresponse and rapid charge transfer performances of 1-D nanotube structure. The enhanced photoelectrochemical properties mainly benefit from the unique architecture features of nanotube array structure.

  13. Fabrication and electrochemical behavior of single-walled carbon nanotube/graphite-based electrode

    International Nuclear Information System (INIS)

    Moghaddam, Abdolmajid Bayandori; Ganjali, Mohammad Reza; Dinarvand, Rassoul; Razavi, Taherehsadat; Riahi, Siavash; Rezaei-Zarchi, Saeed; Norouzi, Parviz

    2009-01-01

    An electrochemical method for determining the dihydroxybenzene derivatives on glassy carbon (GC) has been developed. In this method, the performance of a single-walled carbon nanotube (SWCNT)/graphite-based electrode, prepared by mixing SWCNTs and graphite powder, was described. The resulting electrode shows an excellent behavior for redox of 3,4-dihydroxybenzoic acid (DBA). SWCNT/graphite-based electrode presents a significant decrease in the overvoltage for DBA oxidation as well as a dramatic improvement in the reversibility of DBA redox behavior in comparison with graphite-based and glassy carbon (GC) electrodes. In addition, scanning electron microscopy (SEM) and atomic force microscopy (AFM) procedures performed for used SWCNTs

  14. High power density supercapacitor electrodes of carbon nanotube films by electrophoretic deposition

    International Nuclear Information System (INIS)

    Du Chunsheng; Pan Ning

    2006-01-01

    Carbon nanotube thin films have been successfully fabricated by the electrophoretic deposition technique. The supercapacitors built from such thin film electrodes have a very small equivalent series resistance, and a high specific power density over 20 kW kg -1 was thus obtained. More importantly, the supercapacitors showed superior frequency response. Our study also demonstrated that these carbon nanotube thin films can serve as coating layers over ordinary current collectors to drastically enhance the electrode performance, indicating a huge potential in supercapacitor and battery manufacturing

  15. Nanoindentation study of the mechanical behavior of TiO{sub 2} nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Y. N.; Wang, M. C.; Oloyede, A.; Bell, J. M.; Yan, C., E-mail: c2.yan@qut.edu.au [School of Chemistry, Physics and Mechanical Engineering, Science and Engineering Faculty, Queensland University of Technology (QUT), Brisbane, Queensland 4001 (Australia); Liu, M. N. [i-Lab, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Science, Suzhou (China)

    2015-10-14

    Titanium dioxide (TiO{sub 2}) nanotube arrays are attracting increasing attention for use in solar cells, lithium-ion batteries, and biomedical implants. To take full advantage of their unique physical properties, such arrays need to maintain adequate mechanical integrity in applications. However, the mechanical performance of TiO{sub 2} nanotube arrays is not well understood. In this work, we investigate the deformation and failure of TiO{sub 2} nanotube arrays using the nanoindentation technique. We found that the load–displacement response of the arrays strongly depends on the indentation depth and indenter shape. Substrate-independent elastic modulus and hardness can be obtained when the indentation depth is less than 2.5% of the array height. The deformation mechanisms of TiO{sub 2} nanotube arrays by Berkovich and conical indenters are closely associated with the densification of TiO{sub 2} nanotubes under compression. A theoretical model for deformation of the arrays under a large-radius conical indenter is also proposed.

  16. Nanoindentation study of the mechanical behavior of TiO2 nanotube arrays

    International Nuclear Information System (INIS)

    Xu, Y. N.; Wang, M. C.; Oloyede, A.; Bell, J. M.; Yan, C.; Liu, M. N.

    2015-01-01

    Titanium dioxide (TiO 2 ) nanotube arrays are attracting increasing attention for use in solar cells, lithium-ion batteries, and biomedical implants. To take full advantage of their unique physical properties, such arrays need to maintain adequate mechanical integrity in applications. However, the mechanical performance of TiO 2 nanotube arrays is not well understood. In this work, we investigate the deformation and failure of TiO 2 nanotube arrays using the nanoindentation technique. We found that the load–displacement response of the arrays strongly depends on the indentation depth and indenter shape. Substrate-independent elastic modulus and hardness can be obtained when the indentation depth is less than 2.5% of the array height. The deformation mechanisms of TiO 2 nanotube arrays by Berkovich and conical indenters are closely associated with the densification of TiO 2 nanotubes under compression. A theoretical model for deformation of the arrays under a large-radius conical indenter is also proposed

  17. Direct electrodeposition of highly ordered gold nanotube arrays for use in non-enzymatic amperometric sensing of glucose

    International Nuclear Information System (INIS)

    Tian, Taolei; Dong, Junping; Xu, Jiaqiang

    2016-01-01

    The authors describe vertically aligned gold nanotube arrays (Au-NTAs) and gold nanowire arrays (Au-NWAs) that were directly grown in alumina oxide templates by galvanostatic deposition. The morphology of the gold arrays can be controlled by adjusting the pH value of the plating bath. Scanning electron microscopy shows the nanoarrays to be highly ordered (with an average length of around 2 μm), and the opening width of the gold nanotube arrays to be uniform (with diameters of around 50 nm). The electrocatalytic activities of the Au-NTAs and Au-NWAs deposited on a glassy carbon electrode toward glucose oxidation were compared by cyclic voltammetry and amperometry at pH 7.2. The Au-NTAs yield higher amperometric currents. The respective glucose sensor, when operated at a working potential of 0.25 V (vs. SCE), exhibits a linear range that extends from 5 μM to 16.4 mM concentrations of glucose, a sensitivity of 44.2 μA mM"−"1 cm"−"2, and a detection limit of 2.1 μM (at an S/N ratio of 3). The excellent sensing performance is attributed to the large surface area and the fast electron transfer rate for the one-dimensional gold nanoarrays (author)

  18. Enhanced photoelectrochemical water splitting performance of anodic TiO(2) nanotube arrays by surface passivation.

    Science.gov (United States)

    Gui, Qunfang; Xu, Zhen; Zhang, Haifeng; Cheng, Chuanwei; Zhu, Xufei; Yin, Min; Song, Ye; Lu, Linfeng; Chen, Xiaoyuan; Li, Dongdong

    2014-10-08

    One-dimensional anodic titanium oxide nanotube (TONT) arrays provide a direct pathway for charge transport, and thus hold great potential as working electrodes for electrochemical energy conversion and storage devices. However, the prominent surface recombination due to the large amount surface defects hinders the performance improvement. In this work, the surface states of TONTs were passivated by conformal coating of high-quality Al2O3 onto the tubular structures using atomic layer deposition (ALD). The modified TONT films were subsequently employed as anodes for photoelectrochemical (PEC) water splitting. The photocurrent (0.5 V vs Ag/AgCl) recorded under air mass 1.5 global illumination presented 0.8 times enhancement on the electrode with passivation coating. The reduction of surface recombination rate is responsible for the substantially improved performance, which is proposed to have originated from a decreased interface defect density in combination with a field-effect passivation induced by a negative fixed charge in the Al2O3 shells. These results not only provide a physical insight into the passivation effect, but also can be utilized as a guideline to design other energy conversion devices.

  19. Carbon Nanotubes Counter Electrode for Dye-Sensitized Solar Cells Application

    Directory of Open Access Journals (Sweden)

    Drygała A.

    2016-06-01

    Full Text Available The influence of the carbon nanotubes counter electrode deposited on the FTO glass substrates on the structure and optoelectrical properties of dye-sensitized solar cells counter electrode (CE was analysed. Carbon materials have been applied in DSSC s in order to produce low-cost solar cells with reasonable efficiency. Platinum is a preferred material for the counter electrode because of its high conductivity and catalytic activity. However, the costs of manufacturing of the platinum counter electrode limit its use to large-scale applications in solar cells. This paper presents the results of examining the structure and properties of the studied layers, defining optical properties of conductive layers and electrical properties of dye-sensitized solar cells manufactured with the use of carbon nanotubes.

  20. Solid-state, polymer-based fiber solar cells with carbon nanotube electrodes.

    Science.gov (United States)

    Liu, Dianyi; Zhao, Mingyan; Li, Yan; Bian, Zuqiang; Zhang, Luhui; Shang, Yuanyuan; Xia, Xinyuan; Zhang, Sen; Yun, Daqin; Liu, Zhiwei; Cao, Anyuan; Huang, Chunhui

    2012-12-21

    Most previous fiber-shaped solar cells were based on photoelectrochemical systems involving liquid electrolytes, which had issues such as device encapsulation and stability. Here, we deposited classical semiconducting polymer-based bulk heterojunction layers onto stainless steel wires to form primary electrodes and adopted carbon nanotube thin films or densified yarns to replace conventional metal counter electrodes. The polymer-based fiber cells with nanotube film or yarn electrodes showed power conversion efficiencies in the range 1.4% to 2.3%, with stable performance upon rotation and large-angle bending and during long-time storage without further encapsulation. Our fiber solar cells consisting of a polymeric active layer sandwiched between steel and carbon electrodes have potential in the manufacturing of low-cost, liquid-free, and flexible fiber-based photovoltaics.

  1. 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.

  2. Biophotofuel cell anode containing self-organized titanium dioxide nanotube array

    Energy Technology Data Exchange (ETDEWEB)

    Gan, Yong X., E-mail: yong.gan@utoledo.edu [Mechanical, Industrial and Manufacturing Engineering, College of Engineering, University of Toledo, 2801 W Bancroft Street, Toledo, OH 43606 (United States); Gan, Bo J. [Ottawa Hills High School, 2532 Evergreen Road, Toledo, OH 43606 (United States); Su Lusheng [Mechanical, Industrial and Manufacturing Engineering, College of Engineering, University of Toledo, 2801 W Bancroft Street, Toledo, OH 43606 (United States)

    2011-09-15

    Graphical abstract: Highlights: {center_dot} A photoactive anode containing highly ordered TiO{sub 2} nanotube array was made and the formation mechanism of self-organized TiO{sub 2} nanotube array on Ti was revealed. {center_dot} Effect of electrolyte concentration and voltage on the size distribution of the nanotubes was investigated. {center_dot} Self-organized TiO{sub 2} nanotube array anode possesses good photo-catalytic behavior of biomass decomposition under ultraviolet (UV) radiation. {center_dot} The fuel cell generates electricity and hydrogen via photoelectrochemical decomposition of ethanol, apple vinegar, sugar and tissue paper. - Abstract: We made a biophotofuel cell consisting of a titanium dioxide nanotube array photosensitive anode for biomass decomposition, and a low-hydrogen overpotential metal, Pt, as the cathode for hydrogen production. The titanium dioxide nanotubes (TiO{sub 2} NTs) were prepared via electrochemical oxidation of pure Ti in NaF solutions. Scanning electron microscopy was used to analyze the morphology of the nanotubes. The average diameter, wall thickness and length of the as-prepared TiO{sub 2} NTs were 88 {+-} 16 nm, 10 {+-} 2 nm and 491 {+-} 56 nm, respectively. Such dimensions are affected by the NaF concentration and the applied voltage during processing. Higher NaF concentrations result in the formation of longer and thicker nanotubes. The higher the voltage is, the thicker the nanotubes. The photosensitive anode made from the highly ordered TiO{sub 2} NTs has good photo-catalytic property, as can be seen from the test results of ethanol, apple vinegar, sugar and tissue paper decomposition under ultraviolet (UV) radiation. It is concluded that the biophotofuel cell with the TiO{sub 2} nanotube photoanode and a Pt cathode can generate electricity, hydrogen and clean water depending on the pH value and the oxygen presence in the solutions.

  3. High-efficiency perovskite solar cells based on anatase TiO{sub 2} nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yan, E-mail: huangyan@ecust.edu.cn [School of Chemistry and Molecular Engineering, East China University of Science & Technology, Shanghai 200237 (China); Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States); Wu, Jiamin; Gao, Di [Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, PA 15261 (United States)

    2016-01-01

    Perovskite solar cells (PSCs) based on one-dimensional anatase TiO{sub 2} nanotube arrays were prepared by using a two-step deposition method to fill the arrays of TiO{sub 2} nanotubes in different lengths with perovskite. The photovoltaic performance of PSCs was found to be significantly dependent on the length of the TiO{sub 2} nanotubes, and the power conversion efficiency decreased as the length of the TiO{sub 2} nanotubes increased from ~ 0.40 μm to ~ 0.65 and then to ~ 0.93 μm. The PSC fabricated with ~ 0.40 μm-long anatase TiO{sub 2} nanotube arrays yielded a power conversion efficiency of 11.3% and a fill factor of 0.68 under illumination of 100 mW/cm{sup 2} AM 1.5G simulated sunlight, which is significantly higher than previously reported solar cells based on 1-D TiO{sub 2} nanostructures. Incident photon-to-current efficiency and electrochemical impedance spectroscopy measurements indicated that longer TiO{sub 2} nanotubes led to higher recombination losses of charge carriers, possibly due to poor filling of the nanotube arrays with perovskite. - Highlights: • 1D anatase TiO{sub 2} nanotubes were used to fabricate perovskite solar cells. • The best efficiency of 11.3% was achieved with ~ 0.40 μm-long TiO{sub 2} nanotubes. • The efficiency of the devices decreased with increasing TiO{sub 2} nanotube lengths.

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

    International Nuclear Information System (INIS)

    Fagan-Murphy, Aidan; Patel, Bhavik Anil

    2014-01-01

    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

  5. Large-scale aligned silicon carbonitride nanotube arrays: Synthesis, characterization, and field emission property

    International Nuclear Information System (INIS)

    Liao, L.; Xu, Z.; Liu, K. H.; Wang, W. L.; Liu, S.; Bai, X. D.; Wang, E. G.; Li, J. C.; Liu, C.

    2007-01-01

    Large-scale aligned silicon carbonitride (SiCN) nanotube arrays have been synthesized by microwave-plasma-assisted chemical vapor deposition using SiH 4 , CH 4 , and N 2 as precursors. The three elements of Si, C, and N are chemically bonded with each other and the nanotube composition can be adjusted by varying the SiH 4 concentration, as revealed by electron energy loss spectroscopy and x-ray photoelectron spectroscopy. The evolution of microstructure of the SiCN nanotubes with different Si concentrations was characterized by high-resolution transmission electron microscopy and Raman spectroscopy. The dependence of field emission characteristics of the SiCN nanotubes on the composition has been investigated. With the increasing Si concentration, the SiCN nanotube exhibits more favorable oxidation resistance, which suggests that SiCN nanotube is a promising candidate as stable field emitter

  6. Enhanced performance of electrospun carbon fibers modified with carbon nanotubes: promising electrodes for enzymatic biofuel cells.

    Science.gov (United States)

    Engel, A Both; Cherifi, A; Tingry, S; Cornu, D; Peigney, A; Laurent, Ch

    2013-06-21

    New nanostructured electrodes, promising for the production of clean and renewable energy in biofuel cells, were developed with success. For this purpose, carbon nanofibers were produced by the electrospinning of polyacrylonitrile solution followed by convenient thermal treatments (stabilization followed by carbonization at 1000, 1200 and 1400° C), and carbon nanotubes were adsorbed on the surfaces of the fibers by a dipping method. The morphology of the developed electrodes was characterized by several techniques (SEM, Raman spectroscopy, electrical conductivity measurement). The electrochemical properties were evaluated through cyclic voltammetry, where the influence of the carbonization temperature of the fibers and the beneficial contribution of the carbon nanotubes were observed through the reversibility and size of the redox peaks of K3Fe(CN)6 versus Ag/AgCl. Subsequently, redox enzymes were immobilized on the electrodes and the electroreduction of oxygen to water was realized as a test of their efficiency as biocathodes. Due to the fibrous and porous structure of these new electrodes, and to the fact that carbon nanotubes may have the ability to promote electron transfer reactions of redox biomolecules, the new electrodes developed were capable of producing higher current densities than an electrode composed only of electrospun carbon fibers.

  7. A multichannel scala tympani electrode array incorporating a drug delivery system for chronic intracochlear infusion.

    Science.gov (United States)

    Shepherd, Robert K; Xu, Jin

    2002-10-01

    We have developed a novel scala tympani electrode array suitable for use in experimental animals. A unique feature of this array is its ability to chronically deliver pharmacological agents to the scala tympani. The design of the electrode array is described in detail. Experimental studies performed in guinea pigs confirm that this array can successfully deliver various drugs to the cochlea while chronically stimulating the auditory nerve.

  8. Carbon Nanotube Arrays for Intracellular Delivery and Biological Applications

    Science.gov (United States)

    Golshadi, Masoud

    Introducing nucleic acids into mammalian cells is a crucial step to elucidate biochemical pathways, modify gene expression in immortalized cells, primary cells, and stem cells, and intoduces new approaches for clinical diagnostics and therapeutics. Current gene transfer technologies, including lipofection, electroporation, and viral delivery, have enabled break-through advances in basic and translational science to enable derivation and programming of embryonic stem cells, advanced gene editing using CRISPR (Clustered regularly interspaced short palindromic repeats), and development of targeted anti-tumor therapy using chimeric antigen receptors in T-cells (CAR-T). Despite these successes, current transfection technologies are time consuming and limited by the inefficient introduction of test molecules into large populations of target cells, and the cytotoxicity of the techniques. Moreover, many cell types cannot be consistently transfected by lipofection or electroporation (stem cells, T-cells) and viral delivery has limitations to the size of experimental DNA that can be packaged. In this dissertation, a novel coverslip-like platform consisting of an array of aligned hollow carbon nanotubes (CNTs) embedded in a sacrificial template is developed that enhances gene transfer capabilities, including high efficiency, low toxicity, in an expanded range of target cells, with the potential to transfer mixed combinations of protein and nucleic acids. The CNT array devices are fabricated by a scalable template-based manufacturing method using commercially available membranes, eliminating the need for nano-assembly. High efficient transfection has been demonstrated by delivering various cargos (nanoparticles, dye and plasmid DNA) into populations of cells, achieving 85% efficiency of plasmid DNA delivery into immortalized cells. Moreover, the CNT-mediated transfection of stem cells shows 3 times higher efficiency compared to current lipofection methods. Evaluating the cell

  9. The detection of improvised nonmilitary peroxide based explosives using a titania nanotube array sensor

    International Nuclear Information System (INIS)

    Banerjee, Subarna; Mohapatra, Susanta K; Misra, Mano; Mishra, Indu B

    2009-01-01

    There is a critical need to develop an efficient, reliable and highly selective sensor for the detection of improvised nonmilitary explosives. This paper describes the utilization of functionalized titania nanotube arrays for sensing improvised organic peroxide explosives such as triacetone triperoxide (TATP). TATP forms complexes with titania nanotube arrays (prepared by anodization and sensitized with zinc ions) and thus affects the electron state of the nanosensing device, which is signaled as a change in current of the overall nanotube material. The response is rapid and a signal of five to eight orders of magnitude is observed. These nanotube array sensors can be used as hand-held miniaturized devices as well as large scale portable units for military and homeland security applications.

  10. The detection of improvised nonmilitary peroxide based explosives using a titania nanotube array sensor.

    Science.gov (United States)

    Banerjee, Subarna; Mohapatra, Susanta K; Misra, Mano; Mishra, Indu B

    2009-02-18

    There is a critical need to develop an efficient, reliable and highly selective sensor for the detection of improvised nonmilitary explosives. This paper describes the utilization of functionalized titania nanotube arrays for sensing improvised organic peroxide explosives such as triacetone triperoxide (TATP). TATP forms complexes with titania nanotube arrays (prepared by anodization and sensitized with zinc ions) and thus affects the electron state of the nanosensing device, which is signaled as a change in current of the overall nanotube material. The response is rapid and a signal of five to eight orders of magnitude is observed. These nanotube array sensors can be used as hand-held miniaturized devices as well as large scale portable units for military and homeland security applications.

  11. Determination of the effective Young's modulus of vertically aligned carbon nanotube arrays: a simple nanotube-based varactor

    International Nuclear Information System (INIS)

    Olofsson, Niklas; Eriksson, Anders; Ek-Weis, Johan; Campbell, Eleanor E B; Idda, Tonio

    2009-01-01

    The electromechanical properties of arrays of vertically aligned multiwalled carbon nanotubes were studied in a parallel plate capacitor geometry. The electrostatic actuation was visualized using both optical microscopy and scanning electron microscopy, and highly reproducible behaviour was achieved for actuation voltages below the pull-in voltage. The walls of vertically aligned carbon nanotubes behave as solid cohesive units. The effective Young's modulus for the carbon nanotube arrays was determined by comparing the actuation results with the results of electrostatic simulations and was found to be exceptionally low, of the order of 1-10 MPa. The capacitance change and Q-factor were determined by measuring the frequency dependence of the radio-frequency transmission. Capacitance changes of over 20% and Q-factors in the range 100-10 were achieved for a frequency range of 0.2-1.5 GHz.

  12. Synthesis and optical characterization of carbon nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Rahman, Md. Mahfuzur, E-mail: mrahman@masdar.ac.ae [Institute Centre for Energy (iEnergy), Mechanical and Materials Engineering Department, Masdar Institute of Science and Technology (MIST), P.O. Box 54224, Abu Dhabi (United Arab Emirates); Younes, Hammad [Institute Centre for Energy (iEnergy), Mechanical and Materials Engineering Department, Masdar Institute of Science and Technology (MIST), P.O. Box 54224, Abu Dhabi (United Arab Emirates); Ni, George [Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Ave, Cambridge, MA 02139 (United States); Zhang, TieJun [Institute Centre for Energy (iEnergy), Mechanical and Materials Engineering Department, Masdar Institute of Science and Technology (MIST), P.O. Box 54224, Abu Dhabi (United Arab Emirates); Al Ghaferi, Amal, E-mail: aalghaferi@masdar.ac.ae [Institute Centre for Energy (iEnergy), Mechanical and Materials Engineering Department, Masdar Institute of Science and Technology (MIST), P.O. Box 54224, Abu Dhabi (United Arab Emirates)

    2016-05-15

    Highlights: • Controlling metallicity and vertical alignment of CNT forest by changing hydrogen catalyst annealing time and growth pressure. • Verifying metallicity using Raman spectroscopy of top CNT layer. • Optical characterization of CNT forest using UV–vis–NIR spectrophotometer. - Abstract: Catalyst annealing time and growth pressure play a crucial role in the chiral selective and high-efficiency growth of single-walled carbon nanotubes (SWCNTs) during low pressure chemical vapor deposition (LPCVD). We achieved a high growth rates for SWCNTs and a change the chiral distribution towards metallic (n, m) increasing the catalyst annealing time in hydrogen. A strong correlation is revealed between the catalyst annealing time at lower growth pressures and the shape of the G band, which indicates the metallic or semiconducting nature of the SWCNT and predict the chirality distribution. Under a 15 min annealing time and 10 mbar of growth pressure, the bottom of the G band is broadened with a sharp G{sup −} peak, and the G-band exhibited asymmetrical Breit–Wigner–Fano (BWF) shape. In addition, the growth of SWCNTs with smaller diameters and rich in metallic character is confirmed by the shift of the G-band to a smaller Raman frequency. Homogeneity and vertical alignment of as-grown SWCNT arrays are optically studied using UV/vis/NIR Spectrophotometer. Wavelength-independent and low reflectance resulted from the growth of uniform arrays of SWCNTs. Because of their tunable electronic and optical properties, selective growth of SWCNTs promises great application potential, particularly in electronics and solar industries.

  13. Electrochemical detection of nitrite based on the polythionine/carbon nanotube modified electrode

    International Nuclear Information System (INIS)

    Deng, Chunyan; Chen, Jinzhuo; Nie, Zhou; Yang, Minghui; Si, Shihui

    2012-01-01

    In this paper, thionine was electro-polymerized onto the surface of carbon nanotube (CNT)-modified glassy carbon (GC) to fabricate the polythionine (PTH)/CNT/GC electrode. It was found that the electro-reduction current of nitrite was enhanced greatly at the PTH/CNT/GC electrode. It may be demonstrated that PTH was used as a mediator for electrocatalytic reduction of nitrite, and CNTs as an excellent nanomaterial can improve the electron transfer between the electrode and nitrite. Therefore, based on the synergic effect of PTH and CNTs, the PTH/CNT/GC electrode was employed to detect nitrite, and the high sensitivity of 5.81 μA mM −1 , and the detection limit of 1.4 × 10 −6 M were obtained. Besides, the modified electrode showed an inherent stability, fast response time, and good anti-interference ability. These suggested that the PTH/CNT/GC electrode was favorable and reliable for the detection of nitrite. - Highlights: ► Polythionine (PTH) was used as a mediator for electrocatalytic reduction of nitrite. ► Carbon nanotubes (CNTs) improve electron transfer between the electrode and nitrite. ► The PTH/CNT/glassy carbon electrode showed excellent nitrite detection performance.

  14. Impedance response of carbon nanotube-titania electrodes dried under modified gravity

    International Nuclear Information System (INIS)

    Ordenana-Martinez, A.S.; Rincon, M.E.; Vargas, M.; Ramos, E.

    2011-01-01

    The synthesis and impregnation of porous titania films by commercial multiwalled carbon nanotubes and nanotube rich carbon soot are reported. The samples were dried under terrestrial gravity g and in a centrifuge accelerated at 13 g. X-Ray Diffraction data and Scanning Electron Microscopy images indicated differences in the crystal structure and tendency to agglomeration in both carbon types, providing different microstructures of functionally graded electrodes. Drying the samples in a centrifuge helps to the distribution of carbon nanoparticles and to the decrement of the impedance at the contact interfaces. The presence of titania weakens the differences observed in both drying protocols, but not the differences due to the carbon source. Superior capacitance and network conductivity were observed in electrodes based on commercial carbon nanotubes.

  15. A three-dimensional carbon nanotube/graphene sandwich and its application as electrode in supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Zhuangjun; Yan, Jun; Wei, Tong; Feng, Jing; Zhang, Milin [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin (China); Zhi, Linjie [National Center for Nanoscience and Technology of China, Beijing (China); Zhang, Qiang; Qian, Weizhong; Wei, Fei [Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing (China)

    2010-09-01

    Three-dimensional carbon nanotube/graphene sandwich structures with CNT pillars grown in between the graphene layers have been developed by chemical vapor deposition. The special structure endows the high-rate transportation of electrolyte ions and electrons throughout the electrode matrix, resulting in excellent electrochemical performance of this hybrid material. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  16. 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

  17. Direct electrodeposition of gold nanotube arrays of rough and porous wall by cyclic voltammetry and its applications of simultaneous determination of ascorbic acid and uric acid

    Energy Technology Data Exchange (ETDEWEB)

    Yang Guangming, E-mail: yangguangmingbs@126.com [Department of Resources and Environment, Baoshan University, Baoshan 678000 (China); Ling, Li [Department of Resources and Environment, Baoshan University, Baoshan 678000 (China); Jinhe, Jiang; Yunhui, Yang [College of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming 650092 (China)

    2012-08-01

    Gold nanotube arrays of rough and porous wall has been synthesized by direct electrodeposition with cyclic voltammetry utilizing anodic aluminum oxide template (AAO) and polycarbonate membrane (PC) during short time (only 3 min and 2 min, respectively). The mechanism of the direct electrodeposition of gold nanotube arrays by cyclic voltammetry (CV) has been discussed. The morphological characterizations of the gold nanotube arrays have been investigated by scanning electron microscopy (SEM). A simultaneous determination of ascorbic acid (AA) and uric acid (UA) by differential pulse voltammetry (DPV) was constructed by attaching gold nanotube arrays (using AAO) onto the surface of a glassy carbon electrode (GCE). The electrochemical behavior of AA and UA at this modified electrode has been studied by CV and differential pulse voltammetry (DPV). The sensor offers an excellent response for AA and UA and the linear response range for AA and UA were 1.02 Multiplication-Sign 10{sup -7}-5.23 Multiplication-Sign 10{sup -4} mol L{sup -1} and 1.43 Multiplication-Sign 10{sup -7}-4.64 Multiplication-Sign 10{sup -4} mol L{sup -1}, the detection limits were 1.12 Multiplication-Sign 10{sup -8} mol L{sup -1} and 2.24 Multiplication-Sign 10{sup -8} mol L{sup -1}, respectively. This sensor shows good regeneration, stability and selectivity and has been used for the determination of AA and UA in real human urine and serum samples with satisfied results. - Graphical abstract: The schematic diagram of formation of Au nanotube arrays (a) and the stepwise procedure of the sensor (b). Highlights: Black-Right-Pointing-Pointer Gold nanotubes array has been synthesized by cyclic voltammetry. Black-Right-Pointing-Pointer The mechanism of deposition of gold nanotube has been discussed. Black-Right-Pointing-Pointer A determination of ascorbic acid and uric acid was constructed by gold array. Black-Right-Pointing-Pointer A satisfied determination of samples can be obtained by this sensor.

  18. Investigation of the influence of geometric parameters of carbon nanotube arrays on their adhesion properties

    Science.gov (United States)

    Il’ina, M. V.; Konshin, A. A.; Il’in, O. I.; Rudyk, N. N.; Fedotov, A. A.; Ageev, O. A.

    2018-03-01

    The results of experimental studies of adhesion of carbon nanotube (CNT) arrays with different geometric parameters and orientations using atomic-force microscopy are presented. The adhesion values of CNT arrays were determined, which were from 82 to 1315 nN depending on the parameters of the array. As a result, it was established that the adhesion of a CNT array increases with an increase in branching and disorientation of the array, as well as with the growth of the aspect ratio of CNTs in the array.

  19. Electrochemical biosensing based on polypyrrole/titania nanotube hybrid

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Yibing, E-mail: ybxie@seu.edu.cn; Zhao, Ye

    2013-12-01

    The glucose oxidase (GOD) modified polypyrrole/titania nanotube enzyme electrode is fabricated for electrochemical biosensing application. The titania nanotube array is grown directly on a titanium substrate through an anodic oxidation process. A thin film of polypyrrole is coated onto titania nanotube array to form polypyrrole/titania nanotube hybrid through a normal pulse voltammetry process. GOD-polypyrrole/titania nanotube enzyme electrode is prepared by the covalent immobilization of GOD onto polypyrrole/titania nanotube hybrid via the cross-linker of glutaraldehyde. The morphology and microstructure of nanotube electrodes are characterized by field emission scanning electron microscopy and Fourier transform infrared analysis. The biosensing properties of this nanotube enzyme electrode have been investigated by means of cyclic voltammetry and chronoamperometry. The hydrophilic polypyrrole/titania nanotube hybrid provides highly accessible nanochannels for GOD encapsulation, presenting good enzymatic affinity. As-formed GOD-polypyrrole/titania nanotube enzyme electrode well conducts bioelectrocatalytic oxidation of glucose, exhibiting a good biosensing performance with a high sensitivity, low detection limit and wide linear detection range. - Graphical abstract: The schematic diagram presents the fabrication of glucose oxidase modified polypyrrole/titania (GOD-PPy/TiO{sub 2}) nanotube enzyme electrode for biosensing application. - Highlights: • Hydrophilic polypyrrole/titania nanotube hybrid is well used as biosensing substrate. • Polypyrrole promotes GOD immobilization on titania nanotubes via glutaraldehyde. • GOD-polypyrrole/titania enzyme electrode shows good bioelectrocatalytic reactivity.

  20. Electrochemical biosensing based on polypyrrole/titania nanotube hybrid

    International Nuclear Information System (INIS)

    Xie, Yibing; Zhao, Ye

    2013-01-01

    The glucose oxidase (GOD) modified polypyrrole/titania nanotube enzyme electrode is fabricated for electrochemical biosensing application. The titania nanotube array is grown directly on a titanium substrate through an anodic oxidation process. A thin film of polypyrrole is coated onto titania nanotube array to form polypyrrole/titania nanotube hybrid through a normal pulse voltammetry process. GOD-polypyrrole/titania nanotube enzyme electrode is prepared by the covalent immobilization of GOD onto polypyrrole/titania nanotube hybrid via the cross-linker of glutaraldehyde. The morphology and microstructure of nanotube electrodes are characterized by field emission scanning electron microscopy and Fourier transform infrared analysis. The biosensing properties of this nanotube enzyme electrode have been investigated by means of cyclic voltammetry and chronoamperometry. The hydrophilic polypyrrole/titania nanotube hybrid provides highly accessible nanochannels for GOD encapsulation, presenting good enzymatic affinity. As-formed GOD-polypyrrole/titania nanotube enzyme electrode well conducts bioelectrocatalytic oxidation of glucose, exhibiting a good biosensing performance with a high sensitivity, low detection limit and wide linear detection range. - Graphical abstract: The schematic diagram presents the fabrication of glucose oxidase modified polypyrrole/titania (GOD-PPy/TiO 2 ) nanotube enzyme electrode for biosensing application. - Highlights: • Hydrophilic polypyrrole/titania nanotube hybrid is well used as biosensing substrate. • Polypyrrole promotes GOD immobilization on titania nanotubes via glutaraldehyde. • GOD-polypyrrole/titania enzyme electrode shows good bioelectrocatalytic reactivity

  1. Biaxially stretchable supercapacitors based on the buckled hybrid fiber electrode array

    Science.gov (United States)

    Zhang, Nan; Zhou, Weiya; Zhang, Qiang; Luan, Pingshan; Cai, Le; Yang, Feng; Zhang, Xiao; Fan, Qingxia; Zhou, Wenbin; Xiao, Zhuojian; Gu, Xiaogang; Chen, Huiliang; Li, Kewei; Xiao, Shiqi; Wang, Yanchun; Liu, Huaping; Xie, Sishen

    2015-07-01

    In order to meet the growing need for smart bionic devices and epidermal electronic systems, biaxial stretchability is essential for energy storage units. Based on porous single-walled carbon nanotube/poly(3,4-ethylenedioxythiophene) (SWCNT/PEDOT) hybrid fiber, we designed and fabricated a biaxially stretchable supercapacitor, which possesses a unique configuration of the parallel buckled hybrid fiber array. Owing to the reticulate SWCNT film and the improved fabrication technique, the hybrid fiber retained its porous architecture both outwardly and inwardly, manifesting a superior capacity of 215 F g-1. H3PO4-polyvinyl alcohol gel with an optimized component ratio was introduced as both binder and stretchable electrolyte, which contributed to the regularity and stability of the buckled fiber array. The buckled structure and the quasi one-dimensional character of the fibers endow the supercapacitor with 100% stretchability along all directions. In addition, the supercapacitor exhibited good transparency, as well as excellent electrochemical properties and stability after being stretched 5000 times.In order to meet the growing need for smart bionic devices and epidermal electronic systems, biaxial stretchability is essential for energy storage units. Based on porous single-walled carbon nanotube/poly(3,4-ethylenedioxythiophene) (SWCNT/PEDOT) hybrid fiber, we designed and fabricated a biaxially stretchable supercapacitor, which possesses a unique configuration of the parallel buckled hybrid fiber array. Owing to the reticulate SWCNT film and the improved fabrication technique, the hybrid fiber retained its porous architecture both outwardly and inwardly, manifesting a superior capacity of 215 F g-1. H3PO4-polyvinyl alcohol gel with an optimized component ratio was introduced as both binder and stretchable electrolyte, which contributed to the regularity and stability of the buckled fiber array. The buckled structure and the quasi one-dimensional character of the

  2. Adsorptive stripping voltammetric determination of nitroimidazole derivative on multiwalled carbon nanotube modified electrodes: influence of size and functionalization of nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Jara-Ulloa, Paola; Canete-Rosales, Paulina; Nunez-Vergara, Luis J; Squella, Juan A., E-mail: asquella@ciq.uchile.c [University of Chile, Santiago (Chile). Chemical and Pharmaceutical Sciences Faculty. Bioelectrochemistry Lab.

    2011-07-01

    1-Methyl-4-nitro-2-bromine methylimidazole (4-NimMeBr), was electrochemically reduced on mercury, glassy carbon and multiwalled carbon nanotubes (MWCNT) modified electrodes. 4-NimMeBr was adsorbed on the MWCNT modified electrode thus permitting the implementation of an adsorptive stripping voltammetric (ASV) method. We have used 4-NimMeBr as a prototype electroactive nitro compound to study the effect of both the size of the nanotubes and its functionalization by oxidation. The oxidized MWCNT forms better dispersions than the non-oxidized, producing electrode surface with higher density of MWCNT as was determined by electrochemical mapping using scanning electrochemical microscopy (SECM). Under the optimized conditions, the peak current was proportional to the concentration of 4-NimMeBr in the range of 10{sup -6} mol L{sup -1} to 10{sup -4} mol L{sup -1} with detection and quantification limits of 4.41 x 10{sup -6} mol L{sup -1} and 6.21 x 10{sup -6} mol L{sup -1}, respectively. The sensibility of bare electrode was 0.01 {mu}A per mmol L{sup -1}, which was lower than the value of 5.34 and 6.97 mA per mmol L{sup -1} obtained using short and large oxidized MWCNT, respectively. (author)

  3. In vitro extracellular recording and stimulation performance of nanoporous gold-modified multi-electrode arrays

    Science.gov (United States)

    Kim, Yong Hee; Kim, Gook Hwa; Kim, Ah Young; Han, Young Hwan; Chung, Myung-Ae; Jung, Sang-Don

    2015-12-01

    Objective. Nanoporous gold (Au) structures can reduce the impedance and enhance the charge injection capability of multi-electrode arrays (MEAs) used for interfacing neuronal networks. Even though there are various nanoporous Au preparation techniques, fabrication of MEA based on low-cost electro-codeposition of Ag:Au has not been performed. In this work, we have modified a Au MEA via the electro-codeposition of Ag:Au alloy, followed by the chemical etching of Ag, and report on the in vitro extracellular recording and stimulation performance of the nanoporous Au-modified MEA. Approach. Ag:Au alloy was electro-codeposited on a bilayer lift-off resist sputter-deposition passivated Au MEA followed by chemical etching of Ag to form a porous Au structure. Main results. The porous Au structure was analyzed by scanning electron microscopy and tunneling electron microscopy and found to have an interconnected nanoporous Au structure. The impedance value of the nanoporous Au-modified MEA is 15.4 ± 0.55 kΩ at 1 kHz, accompanied by the base noise V rms of 2.4 ± 0.3 μV. The charge injection limit of the nanoporous Au-modified electrode estimated from voltage transient measurement is approximately 1 mC cm-2, which is comparable to roughened platinum and carbon nanotube electrodes. The charge injection capability of the nanoporous Au-modified MEA was confirmed by observing stimulus-induced spikes at above 0.2 V. The nanoporous Au-modified MEA showed mechanical durability upon ultrasonic treatment for up to an hour. Significance. Electro-codeposition of Ag:Au alloy combined with chemical etching Ag is a low-cost process for fabricating nanoporous Au-modified MEA suitable for establishing the stimulus-response relationship of cultured neuronal networks.

  4. In vitro extracellular recording and stimulation performance of nanoporous gold-modified multi-electrode arrays.

    Science.gov (United States)

    Kim, Yong Hee; Kim, Gook Hwa; Kim, Ah Young; Han, Young Hwan; Chung, Myung-Ae; Jung, Sang-Don

    2015-12-01

    Nanoporous gold (Au) structures can reduce the impedance and enhance the charge injection capability of multi-electrode arrays (MEAs) used for interfacing neuronal networks. Even though there are various nanoporous Au preparation techniques, fabrication of MEA based on low-cost electro-codeposition of Ag:Au has not been performed. In this work, we have modified a Au MEA via the electro-codeposition of Ag:Au alloy, followed by the chemical etching of Ag, and report on the in vitro extracellular recording and stimulation performance of the nanoporous Au-modified MEA. Ag:Au alloy was electro-codeposited on a bilayer lift-off resist sputter-deposition passivated Au MEA followed by chemical etching of Ag to form a porous Au structure. The porous Au structure was analyzed by scanning electron microscopy and tunneling electron microscopy and found to have an interconnected nanoporous Au structure. The impedance value of the nanoporous Au-modified MEA is 15.4 ± 0.55 kΩ at 1 kHz, accompanied by the base noise V rms of 2.4 ± 0.3 μV. The charge injection limit of the nanoporous Au-modified electrode estimated from voltage transient measurement is approximately 1 mC cm(-2), which is comparable to roughened platinum and carbon nanotube electrodes. The charge injection capability of the nanoporous Au-modified MEA was confirmed by observing stimulus-induced spikes at above 0.2 V. The nanoporous Au-modified MEA showed mechanical durability upon ultrasonic treatment for up to an hour. Electro-codeposition of Ag:Au alloy combined with chemical etching Ag is a low-cost process for fabricating nanoporous Au-modified MEA suitable for establishing the stimulus-response relationship of cultured neuronal networks.

  5. Fabrication and electrochemical characterization of multi-walled carbon nanotube electrodes for applications to nano-electrochemical sensing

    International Nuclear Information System (INIS)

    Hwang, Sookhyun; Choi, Hyonkwang; Jeon, Minhyon; Vedala, Harindra; Kim, Taehyung; Choi, Wonbong

    2010-01-01

    In this study, we fabricated and electrochemically characterized two types of individual carbon nanotube electrodes: an as-produced multi-walled carbon nanotube (MWNT) electrode and a modified MWNT electrode. As-produced MWNTs were electrically contacted with Au/Ti layers by using nanolithography and RF magnetron sputtering. Open-ended modified MWNT electrodes were fabricated by using a reactive ion etching treatment under an oxygen atmosphere. We also performed cyclic voltammetry measurements to detect aqueous dopamine solutions with different concentrations. We found that an individual MWNT electrode, which had a small effective area, showed good electrochemical performance. The electrocatalytic behavior of the modified electrode, which had 'broken' open ends were better than that of the as-produced electrode with respect to sensitivity. The modified electrode was capable of detecting dopamine at the picomolar level. Therefore, an individual modified MWNT electrode has potential for applications to active components in nanobiosensors.

  6. Electrocatalysis aqueous phenol with carbon nanotubes networks as anodes: Electrodes passivation and regeneration and prevention

    International Nuclear Information System (INIS)

    Gao, Guandao; Vecitis, Chad D.

    2013-01-01

    Highlights: ► The electrochemical filtration used carbon nanotube network is effective to remove aqueous pollutants. ► Electrodes passivation is one of the most urgent challenges to overcome to 3-D electrode technology. ► Generally running system at higher potential can avoid generating polymer. ► Washing electrodes with suitable solvents is an effective alternative for removing polymer if it is not the best. -- Abstract: Electrochemical filtration using three-dimensional carbon nanotube (CNT) networks has been reported to increase the electrooxidation rate of aqueous pollutants due to convective mass transfer enhancements resulting from the flow through the electrode. In regards to the long term application of this novel electrochemical technology, electrode passivation is one of the most important challenges to overcome. Here, electrochemical filtration of aqueous phenol in a sodium sulfate electrolyte is utilized to investigate the primary passivation mechanisms and electrode regeneration methodologies, in which chronoamperometry and effluent total organic carbon measurements are utilized to monitor the passivation process in real-time, and electrochemical impedance spectroscopy, linear sweep voltammetry, and scanning electron microscopy are utilized to examine the CNT networks before passivation, after passivation and after regeneration. Finnaly, the carbon nanotube electrode passivation mechanisms and regeneration methods are discussed. Generally it is better choice to run system at higher potential in order to avoid generating polymer firstly other than regenerate complicatedly it after its passivation. Polymer formation can be prevented by application of an anode potential ≥2.1 V, which can completely mineralize phenol to carbon dioxide etc. and prevent polymerization of phenol. If there is still a bit of polymer formed inevitably, washing electrodes with suitable solvents is an effective alternative

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

    International Nuclear Information System (INIS)

    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. (cross-disciplinary physics and related areas of science and technology)

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

    Science.gov (United States)

    Coppedè, Nicola; Valitova, Irina; Mahvash, Farzaneh; Tarabella, Giuseppe; Ranzieri, Paolo; Iannotta, Salvatore; Santato, Clara; Martel, Richard; Cicoira, Fabio

    2014-12-01

    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.

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

    International Nuclear Information System (INIS)

    Coppedè, Nicola; Tarabella, Giuseppe; Ranzieri, Paolo; Iannotta, Salvatore; Valitova, Irina; Cicoira, Fabio; Mahvash, Farzaneh; Santato, Clara; Martel, Richard

    2014-01-01

    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)

  10. Uniform, dense arrays of vertically aligned, large-diameter single-walled carbon nanotubes.

    Science.gov (United States)

    Han, Zhao Jun; Ostrikov, Kostya

    2012-04-04

    Precisely controlled reactive chemical vapor synthesis of highly uniform, dense arrays of vertically aligned single-walled carbon nanotubes (SWCNTs) using tailored trilayered Fe/Al(2)O(3)/SiO(2) catalyst is demonstrated. More than 90% population of thick nanotubes (>3 nm in diameter) can be produced by tailoring the thickness and microstructure of the secondary catalyst supporting SiO(2) layer, which is commonly overlooked. The proposed model based on the atomic force microanalysis suggests that this tailoring leads to uniform and dense arrays of relatively large Fe catalyst nanoparticles on which the thick SWCNTs nucleate, while small nanotubes and amorphous carbon are effectively etched away. Our results resolve a persistent issue of selective (while avoiding multiwalled nanotubes and other carbon nanostructures) synthesis of thick vertically aligned SWCNTs whose easily switchable thickness-dependent electronic properties enable advanced applications in nanoelectronic, energy, drug delivery, and membrane technologies.

  11. Thermal conductivity of vertically aligned carbon nanotube arrays: Growth conditions and tube inhomogeneity

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Matthew L.; Pham, Quang N.; Saltonstall, Christopher B.; Norris, Pamela M. [Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22904-4746 (United States)

    2014-10-13

    The thermal conductivity of vertically aligned carbon nanotube arrays (VACNTAs) grown on silicon dioxide substrates via chemical vapor deposition is measured using a 3ω technique. For each sample, the VACNTA layer and substrate are pressed to a heating line at varying pressures to extract the sample's thermophysical properties. The nanotubes' structure is observed via transmission electron microscopy and Raman spectroscopy. The presence of hydrogen and water vapor in the fabrication process is tuned to observe the effect on measured thermal properties. The presence of iron catalyst particles within the individual nanotubes prevents the array from achieving the overall thermal conductivity anticipated based on reported measurements of individual nanotubes and the packing density.

  12. Mapping the temporal pole with a specialized electrode array: technique and preliminary results

    International Nuclear Information System (INIS)

    Abel, Taylor J; Rhone, Ariane E; Nourski, Kirill V; Oya, Hiroyuki; Kawasaki, Hiroto; Howard, Matthew A III; Granner, Mark A; Tranel, Daniel T; Griffiths, Timothy D

    2014-01-01

    Temporopolar cortex plays a crucial role in the pathogenesis of temporal lobe epilepsy and subserves important cognitive functions. Because of its shape and position in the middle cranial fossa, complete electrode coverage of the temporal pole (TP) is difficult to achieve using existing devices. We designed a novel TP electrode array that conforms to the surface of temporopolar cortex and achieves dense electrode coverage of this important brain region. A multi-pronged electrode array was designed that can be placed over the surface of the TP using a straightforward insertion technique. Twelve patients with medically intractable epilepsy were implanted with the TP electrode array for purposes of seizure localization. Select patients underwent cognitive mapping by electrocorticographic (ECoG) recording from the TP during a naming task. Use of the array resulted in excellent TP electrode coverage in all patients. High quality ECoG data were consistently obtained for purposes of delineating seizure activity and functional mapping. During a naming task, significant increases in ECoG power were observed within localized subregions of the TP. One patient developed a transient neurological deficit thought to be related to the mass effect of multiple intracranial recording arrays, including the TP array. This deficit resolved following removal of all electrodes. The TP electrode array overcomes limitations of existing devices and enables clinicians and researchers to obtain optimal multi-site recordings from this important brain region. (paper)

  13. Effect of Source, Surfactant, and Deposition Process on Electronic Properties of Nanotube Arrays

    Directory of Open Access Journals (Sweden)

    Dheeraj Jain

    2011-01-01

    Full Text Available The electronic properties of arrays of carbon nanotubes from several different sources differing in the manufacturing process used with a variety of average properties such as length, diameter, and chirality are studied. We used several common surfactants to disperse each of these nanotubes and then deposited them on Si wafers from their aqueous solutions using dielectrophoresis. Transport measurements were performed to compare and determine the effect of different surfactants, deposition processes, and synthesis processes on nanotubes synthesized using CVD, CoMoCAT, laser ablation, and HiPCO.

  14. Control of neuronal network organization by chemical surface functionalization of multi-walled carbon nanotube arrays

    International Nuclear Information System (INIS)

    Liu Jie; Bibari, Olivier; Marchand, Gilles; Benabid, Alim-Louis; Sauter-Starace, Fabien; Appaix, Florence; De Waard, Michel

    2011-01-01

    Carbon nanotube substrates are promising candidates for biological applications and devices. Interfacing of these carbon nanotubes with neurons can be controlled by chemical modifications. In this study, we investigated how chemical surface functionalization of multi-walled carbon nanotube arrays (MWNT-A) influences neuronal adhesion and network organization. Functionalization of MWNT-A dramatically modifies the length of neurite fascicles, cluster inter-connection success rate, and the percentage of neurites that escape from the clusters. We propose that chemical functionalization represents a method of choice for developing applications in which neuronal patterning on MWNT-A substrates is required.

  15. Control of neuronal network organization by chemical surface functionalization of multi-walled carbon nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Liu Jie; Bibari, Olivier; Marchand, Gilles; Benabid, Alim-Louis; Sauter-Starace, Fabien [CEA, LETI-Minatec, 17 Rue des Martyrs, 38054 Grenoble Cedex 9 (France); Appaix, Florence; De Waard, Michel, E-mail: fabien.sauter@cea.fr, E-mail: michel.dewaard@ujf-grenoble.fr [Inserm U836, Grenoble Institute of Neuroscience, Site Sante la Tronche, Batiment Edmond J Safra, Chemin Fortune Ferrini, BP170, 38042 Grenoble Cedex 09 (France)

    2011-05-13

    Carbon nanotube substrates are promising candidates for biological applications and devices. Interfacing of these carbon nanotubes with neurons can be controlled by chemical modifications. In this study, we investigated how chemical surface functionalization of multi-walled carbon nanotube arrays (MWNT-A) influences neuronal adhesion and network organization. Functionalization of MWNT-A dramatically modifies the length of neurite fascicles, cluster inter-connection success rate, and the percentage of neurites that escape from the clusters. We propose that chemical functionalization represents a method of choice for developing applications in which neuronal patterning on MWNT-A substrates is required.

  16. A disposable electrochemical immunosensor arrays using 4-channel screen-printed carbon electrode for simultaneous detection of Escherichia coli O157:H7 and Enterobacter sakazakii

    International Nuclear Information System (INIS)

    Dou, Wenchao; Tang, Weilu; Zhao, Guangying

    2013-01-01

    An electrochemical immunosensor for Escherichia coli O157:H7 (E. coli O157:H7) and Enterobacter sakazakii (E. sakazakii) detection using carbon screen-printed low-density arrays is reported. The sensors were fabricated based on screen-printed carbon arrays containing four carbon working electrode, an integrated carbon counter electrodes and an integrated Ag/AgCl reference electrode. Multi-walled carbon nanotubes (MWCNTs)/sodium alginate (SA)/carboxymethyl chitosan (CMC) composite films were coated on all the working electrodes to enhance the sensitization of the electrode. Horseradish peroxidases (HRP) labeled antibodies of two bacteria were immobilize on different working electrode of the same screen-printed electrode respectively. The immobilization of MWCNTs, HRP labeled antibodies onto the screen-printed carbon electrodes was examined using atom force microscopy (AFM) and cyclic voltammetry (CV). The analytical performance of proposed immunosensor arrays toward E. sakazakii and E. coli O157:H7 was investigated by AFM and CV. Under optimal conditions, the linear range of E. sakazakii and E. coli O157:H7 were from 10 4 to 10 10 cfu/ml, with a detection limit of 4.57 × 10 3 cfu/ml (S/N = 3) and 3.27 × 10 3 cfu/ml (S/N = 3), respectively. The specificity, reproducibility, stability and accuracy of the proposed immunosensor arrays were also evaluated. Two antibodies modified work electrodes were tested and compared in terms of sensitivity and ability to recognize different pathogenic biological species

  17. Interfacial Engineered Polyaniline/Sulfur-doped TiO2 Nanotube Arrays for Ultralong Cycle Lifetime Fiber-Shaped, Solid-State Supercapacitors.

    Science.gov (United States)

    Li, Chun; Wang, Zhuanpei; Li, Shengwen; Cheng, Jianli; Zhang, Yanning; Zhou, Jingwen; Yang, Dan; Tong, Dong-Ge; Wang, Bin

    2018-05-04

    Fiber-shaped supercapacitors (FSCs) have great potential in wearable electronics applications. However, the limited specific surface area and inadequate structural stability caused by the weak interfacial interactions of the electrodes result in relatively low specific capacitance and unsatisfactory cycle lifetime. Herein, solid-state FSCs with high energy density and ultralong cycle lifetime based on polyaniline (PANI)/sulfur-doped TiO2 nanotubes array (PANI/S-TiO2) are fabricated by interfacial engineering. The experimental results and ab initio calculations reveal that S doping can effectively promote the conductivity of titania nanotubes and increase the binding energy of PANI anchored on the electrode surface, leading to much stronger binding of PANI on the surface of the electrode and excellent electrode structure stability. As a result, the FSCs using the PANI/S-TiO2 electrodes deliver a high specific capacitance of 91.9 mF cm-2, a capacitance retention of 93.78% after 12,000 charge/discharge cycles, and an areal energy density of 3.2 µWh cm-2, respectively. Meanwhile, the all-solid-state FSC device retains its excellent flexibility and stable electrochemical capacitance even after bending 150 cycles. The enhanced performances of FSCs could be attributed to the large surface area, short ion diffusion path, high electrical conductivity and engineered interfacial interaction of the rationally designed electrodes.

  18. Magnetization Reversal Mechanism for CoFeB Ferromagnetic Nanotube Arrays

    International Nuclear Information System (INIS)

    Hai-Rui, Liu; Qing-Feng, Lu; Shamaila, S.; Jun-Yang, Chen; Sharif, R.; Xiu-Feng, Han

    2009-01-01

    CoFeB nanotube arrays are fabricated in anodic aluminum oxide (AAO) membranes and track etched polycarbonate (PCTE) membranes by using an electrochemical method, and their magnetic properties are investigated by vibrating sample magnetometry. The coercivity H c and remanent squareness S Q of these CoFeB nanotube arrays are derived from hysteresis loops as a function of angle between the field and tube axis. The H c (θ) curves for CoFeB nanotube arrays in AAO and PCTE membranes show M-type variation, while they change shape from M to mountain-type as the tube length increases. However, the overall easy axis perpendicular to tube axis does not change with tube length. The different angular dependences are attributed to different magnetization reversal mechanisms. (condensed matter: electronicstructure, electrical, magnetic, and opticalproperties)

  19. Fabrication of DNA nanotubes with an array of exterior magnetic nanoparticles.

    Science.gov (United States)

    Rafati, Adele; Zarrabi, Ali; Gill, Pooria

    2017-10-01

    Described here a methodology for arraying of magnetic nanoparticles (MNPs) on the surface of DNA nanotubes (DNTs). Positioning of magnetic nanoparticles at exterior surface of DNTs were shaped after self-assembling of oligonucleotide staples within an M13mp18 DNA scaffold via an origami process. The staples were partially labeled with biotin to be arrayed at the surface of DNTs. Gel retardation assay of the DNTs carrying magnetic nanoparticles indicated a reversely behavioral electrophoretic movement in comparison to the nanotubes have been demonstrated previously. Also, high resolution transmission electron microscopy confirmed positioning magnetic nanoparticles at the exterior surface of DNTs, correctly. Ultrastructural characteristics of these DNA nanotubes using atomic force microscopy demonstrated topographic heights on their surfaces formed through positioning of magnetic nanoparticles outside the tubules. This nanoarchitecture would be potential for multiple arraying of nanoparticles that those be useful as functionalized chimeric nanocarriers for developing novel nanodrugs and nanobiosensors. Copyright © 2017. Published by Elsevier B.V.

  20. All-solid-state flexible microsupercapacitors based on reduced graphene oxide/multi-walled carbon nanotube composite electrodes

    Science.gov (United States)

    Mao, Xiling; Xu, Jianhua; He, Xin; Yang, Wenyao; Yang, Yajie; Xu, Lu; Zhao, Yuetao; Zhou, Yujiu

    2018-03-01

    All-solid-state flexible microsupercapacitors have been intensely investigated in order to meet the rapidly growing demands for portable microelectronic devices. Herein, we demonstrate a facile, readily scalable and cost-effective laser induction process for preparing reduced graphene oxide/multi-walled carbon nanotube composite, which can be used as the interdigital electrodes in microsupercapacitors. The obtained composite exhibits high volumetric capacitance about 49.35 F cm-3, which is nearly 5 times higher than that of the pristine reduced graphene oxide film in aqueous 1.0 M H2SO4 solution (measured at a current density of 5 A cm-3 in a three-electrode testing). Additionally, an all-solid-state flexible microsupercapacitor employing these composite electrodes with PVA/H3PO4 gel electrolyte delivers high volumetric energy density of 6.47 mWh cm-3 at 10 mW cm-3 under the current density of 20 mA cm-3 as well as achieve excellent cycling stability retaining 88.6% of its initial value and outstanding coulombic efficiency after 10,000 cycles. Furthermore, the microsupercapacitors array connected in series/parallel can be easily adjusted to achieve the demands in practical applications. Therefore, this work brings a promising new candidate of prepare technologies for all-solid-state flexible microsupercapacitors as miniaturized power sources used in the portable and wearable electronics.

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

    International Nuclear Information System (INIS)

    Vikkisk, Merilin; Kruusenberg, Ivar; Joost, Urmas; Shulga, Eugene; Tammeveski, Kaido

    2013-01-01

    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 O 2 reduction predominated. The results obtained are significant for the development of nitrogen-doped carbon-based cathodes for alkaline membrane fuel cells.

  2. 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.; Jin, Run Zhi; Stoltenberg, Randall M.; Bao, Zhenan

    2010-01-01

    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

  3. Synthesis and photocatalytic properties of Sn-doped TiO{sub 2} nanotube arrays

    Energy Technology Data Exchange (ETDEWEB)

    Tu Yafang; Huang Shengyou [Department of Physics, Wuhan University, Wuhan 430072 (China); Sang Jianping, E-mail: jpsang@acc-lab.whu.edu.c [Department of Physics, Wuhan University, Wuhan 430072 (China); Department of Physics, Jianghan University, Wuhan 430056 (China); Zou Xianwu [Department of Physics, Wuhan University, Wuhan 430072 (China)

    2009-08-12

    TiO{sub 2} nanotube arrays doped by Sn up to 12 at% have been prepared using template-based liquid phase deposition method. Their morphologies, structures and optical properties have been investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, UV-vis absorption spectroscopy and photoluminescence spectroscopy. The photocatalytic properties of the samples were evaluated with the degradation of methylene blue under UV irradiation. The result shows that doping an appropriate amount of Sn can effectively improve the photocatalytic activity of TiO{sub 2} nanotube arrays, and the optimum dopant amount is found to be 5.6 at% in our experiments.

  4. Nanomanipulation of 2 inch wafer fabrication of vertically aligned carbon nanotube arrays by nanoimprint lithography

    DEFF Research Database (Denmark)

    Bu, Ian Y. Y.; Eichhorn, Volkmar; Carlson, Kenneth

    2011-01-01

    Carbon nanotube (CNT) arrays are typically defined by electron beam lithography (EBL), and hence limited to small areas due to the low throughput. To obtain wafer‐scale fabrication we propose large area thermal nanoimprint lithography (NIL). A 2‐inch stamp master is defined using EBL for subsequent......, efficient production of wafer‐scale/larger arrays of CNTs has been achieved. The CNTs have been deposited by wafer‐scale plasma enhanced chemical vapour deposition (PECVD) of C2H2/NH3. Substrates containing such nanotubes have been used to automate nanorobotic manipulation sequences of individual CNTs...

  5. Magnetic behaviour of arrays of Ni nanowires by electrodeposition into self-aligned titania nanotubes

    International Nuclear Information System (INIS)

    Prida, V.M.; Hernandez-Velez, M.; Cervera, M.; Pirota, K.; Sanz, R.; Navas, D.; Asenjo, A.; Aranda, P.; Ruiz-Hitzky, E.; Batallan, F.; Vazquez, M.; Hernando, B.; Menendez, A.; Bordel, N.; Pereiro, R.

    2005-01-01

    Arrays of Ni nanowires electrodeposited into self-aligned and randomly disordered titania nanotube arrays grown by anodization process are investigated by X-ray diffraction, SEM, rf-GDOES and VSM magnetometry. The titania nanotube outer diameter is about 160 nm, wall thickness ranging from 60 to 70 nm and 300 nm in depth. The so-obtained Ni nanowires reach above 100 nm diameter and 240 nm length, giving rise to coercive fields of 98 and 200 Oe in the perpendicular or parallel to the nanowires axis hysteresis loops, respectively. The formation of magnetic vortex domain states is also discussed

  6. Exploring the alignment of carbon nanotubes dispersed in a liquid crystal matrix using coplanar electrodes

    International Nuclear Information System (INIS)

    Volpati, D.; Massey, M. K.; Kotsialos, A.; Qaiser, F.; Pearson, C.; Tiburzi, G.; Zeze, D. A.; Petty, M. C.; Johnson, D. W.; Coleman, K. S.

    2015-01-01

    We report on the use of a liquid crystalline host medium to align single-walled carbon nanotubes in an electric field using an in-plane electrode configuration. Electron microscopy reveals that the nanotubes orient in the field with a resulting increase in the DC conductivity in the field direction. Current versus voltage measurements on the composite show a nonlinear behavior, which was modelled by using single-carrier space-charge injection. The possibility of manipulating the conductivity pathways in the same sample by applying the electrical field in different (in-plane) directions has also been demonstrated. Raman spectroscopy indicates that there is an interaction between the nanotubes and the host liquid crystal molecules that goes beyond that of simple physical mixing

  7. Layer-by-Layer Assembly of Glucose Oxidase on Carbon Nanotube Modified Electrodes.

    Science.gov (United States)

    Suroviec, Alice H

    2017-01-01

    The use of enzymatically modified electrodes for the detection of glucose or other non-electrochemically active analytes is becoming increasingly common. Direct heterogeneous electron transfer to glucose oxidase has been shown to be kinetically difficult, which is why electron transfer mediators or indirect detection is usually used for monitoring glucose with electrochemical sensors. It has been found, however, that electrodes modified with single or multi-walled carbon nanotubes (CNTs) demonstrate fast heterogeneous electron transfer kinetics as compared to that found for traditional electrodes. Incorporating CNTs into the assembly of electrochemical glucose sensors, therefore, affords the possibility of facile electron transfer to glucose oxidase, and a more direct determination of glucose. This chapter describes the methods used to use CNTs in a layer-by-layer structure along with glucose oxidase to produce an enzymatically modified electrode with high turnover rates, increased stability and shelf-life.

  8. 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.

  9. MnO2/multiwall carbon nanotube/Ni-foam hybrid electrode for electrochemical capacitor

    Science.gov (United States)

    Chen, L. H.; Li, L.; Qian, W. J.; Dong, C. K.

    2018-01-01

    The ternary composites of manganese dioxide/multiwall carbon nanotube/Ni-foam (MnO2/MWNT/Ni-foam) for supercapacitors were fabricated via a hydrothermal method after direct growth of MWNTs on the Ni-foam. The structural properties of the electrodes were characterized by SEM and TEM. The electrode exhibited excellent electrochemical properties from the investigation based on the three-electrode setup. Low contact resistance Rs of about 0.291 Ω between MnO2/MWNT and Ni-foam was reached benefited from the direct growth structure. High capacitance of 355.1 F/g at the current density of 2 A/g was achieved, with good capacitive response at high current density. The MnO2/MWNT/Ni-foam electrode exhibits good stability performance after 2000 cycles at a current of 40 mA.

  10. A new method synthesis polyaniline/multi-walled carbon nanotube composites for supercapacitor electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Pan, J.; Wei, X.; Zhou, S.P. [Shandong Univ. of Technology, Zibo (China). School of Chemical Engineering

    2010-07-01

    A series of polyaniline multi-walled nanotube (PANIMWNT) composite films were prepared using an in situ polymerization technique. Scanning electron microscopy (SEM) was used to characterize the morphology and microstructure of the samples. Cyclic voltammetry (CV), impedance spectroscopy, and galvanostatic charge/discharge analyses were used to determine the electrochemical properties of the PANIMWNT films in a 3-electrode system. The electrochemical performance of PANI, PANIMWNT, and MWNT film performances was then compared. Results of the study showed that the PANI electrodes showed a much higher capacitance than the MWNT and PANIMWNT electrodes. Both the PANI and PANIMWNT nanocomposites showed good electrochemical capacitance. The improved performance of the electrodes was attributed to the presence of sodium hypochlorite (NaClO). 5 refs.

  11. 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.

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

    International Nuclear Information System (INIS)

    Nguyen, Le Huy; Nguyen, Ngoc Thinh; Nguyen, Hai Binh; Tran, Dai Lam; Nguyen, Tuan Dung

    2012-01-01

    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

  13. Planar silver nanowire, carbon nanotube and PEDOT:PSS nanocomposite transparent electrodes

    Science.gov (United States)

    Stapleton, Andrew J.; Yambem, Soniya D.; Johns, Ashley H.; Afre, Rakesh A.; Ellis, Amanda V.; Shapter, Joe G.; Andersson, Gunther G.; Quinton, Jamie S.; Burn, Paul L.; Meredith, Paul; Lewis, David A.

    2015-04-01

    Highly conductive, transparent and flexible planar electrodes were fabricated using interwoven silver nanowires and single-walled carbon nanotubes (AgNW:SWCNT) in a PEDOT:PSS matrix via an epoxy transfer method from a silicon template. The planar electrodes achieved a sheet resistance of 6.6 ± 0.0 Ω/□ and an average transmission of 86% between 400 and 800 nm. A high figure of merit of 367 Ω-1 is reported for the electrodes, which is much higher than that measured for indium tin oxide and reported for other AgNW composites. The AgNW:SWCNT:PEDOT:PSS electrode was used to fabricate low temperature (annealing free) devices demonstrating their potential to function with a range of organic semiconducting polymer:fullerene bulk heterojunction blend systems.

  14. Effects of electrode distance and nature of electrolyte on the diameter of titanium dioxide nanotube

    Energy Technology Data Exchange (ETDEWEB)

    Abbasi, S., E-mail: sum.abbasi@gmail.com; Mohamed, N. M., E-mail: noranimuti-mohamed@petronas.com.my; Singh, B. S. M., E-mail: balbir@petronas.com.my [Department of Fundamental and Applied Sciences Unviersiti Teknologi PETRONAS, 31750, Bandar Seri Iskandar (Malaysia); Abbasi, S. H., E-mail: sarfrazabbasi@gmail.com [SABIC Plastic Application Development Center, Riyadh Technovalley, Riyadh (Saudi Arabia)

    2015-07-22

    The titanium nanotubes were synthesized using viscous electrolytes consisting of ethylene glycol and non-viscous electrolytes consisting of aqueous solution of hydrofluoric acid. Sodium fluoride and ammonium fluoride were utilized as the source of fluorine ions. The samples were then characterized by field emission scanning electron microscope (FE-SEM). Their morphologies were investigated under different anodic potentials and various electrolyte compositions. It was found out that nanotubes can be obtained in fluoride ions and morphology is dependent on various parameters like anodic potential, time, electrolyte composition and the effects by varying the distance between the electrodes on the morphology was also investigated. It was found that by altering the distance between the electrodes, change in the diameter and the porosity was observed.

  15. 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.

  16. Carbon nanotubes functionalized by salts containing stereogenic heteroatoms as electrodes in their battery cells

    Directory of Open Access Journals (Sweden)

    Zdanowska Sandra

    2016-12-01

    Full Text Available This paper concentrates on electrochemical properties of groups of multi-walled carbon nanotubes (MWCNT functionalized with substituents containing a stereogenic heteroatom bonded covalently to the surface of the carbon nanotube. This system was tested in Swagelok-type cells. The cells comprised a system (functionalized CNT with salts containing S and P atoms with a working electrode, microfiber separators soaked with electrolyte solution, and a lithium foil counter/reference (commercial LiCoO2 electrode. The electrolyte solution was 1 M LiPF6 in propylene carbonate. Using standard techniques (cyclic voltammetry/chronopotentiometry, galvanostatic cycling was performed on the cells at room temperature with a CH Instruments Model 600E potentiostat/galvanostat electrochemical measurements. Methods of functionalization CNT were compared in terms of the electrochemical properties of the studied systems. In all systems, the process of charge/discharge was observed.

  17. Enhanced electrochemical activity using vertically aligned carbon nanotube electrodes grown on carbon fiber

    Directory of Open Access Journals (Sweden)

    Evandro Augusto de Morais

    2011-09-01

    Full Text Available Vertically aligned carbon nanotubes were successfully grown on flexible carbon fibers by plasma enhanced chemical vapor deposition. The diameter of the CNT is controllable by adjusting the thickness of the catalyst Ni layer deposited on the fiber. Vertically aligned nanotubes were grown in a Plasma Enhanced Chemical Deposition system (PECVD at a temperature of 630 ºC, d.c. bias of -600 V and 160 and 68 sccm flow of ammonia and acetylene, respectively. Using cyclic voltammetry measurements, an increase of the surface area of our electrodes, up to 50 times higher, was observed in our samples with CNT. The combination of VACNTs with flexible carbon fibers can have a significant impact on applications ranging from sensors to electrodes for fuel cells.

  18. Improved 2-D resistivity imaging of features in covered karst terrain with arrays of implanted electrodes

    Science.gov (United States)

    Kiflu, H. G.; Kruse, S. E.; Harro, D.; Loke, M. H.; Wilkinson, P. B.

    2013-12-01

    Electrical resistivity tomography is commonly used to identify geologic features associated with sinkhole formation. In covered karst terrain, however, it can be difficult to resolve the depth to top of limestone with this method. This is due to the fact that array lengths, and hence depth of resolution, are often limited by residential or commercial lot dimensions in urban environments. Furthermore, the sediments mantling the limestone are often clay-rich and highly conductive. The resistivity method has limited sensitivity to resistive zones beneath conductive zones. This sensitivity can be improved significantly with electrodes implanted at depth in the cover sediments near the top of limestone. An array of deep electrodes is installed with direct push technology in the karst cover. When combined with a surface array in which each surface electrode is underlain by a deep electrode, the array geometry is similar to a borehole array turned on its side. This method, called the Multi-Electrode Resistivity Implant Technique (MERIT), offers the promise of significantly improved resolution of epikarst and cover collapse development zones in the overlying sediment, the limestone or at the sediment-bedrock interface in heterogeneous karst environments. With a non-traditional array design, the question of optimal array geometries arises. Optimizing array geometries is complicated by the fact that many plausible 4-electrode readings will produce negative apparent resistivity values, even in homogeneous terrain. Negative apparent resistivities cannot be used in inversions based on the logarithm of the apparent resistivity. New algorithms for seeking optimal array geometries have been developed by modifying the 'Compare R' method of Wilkinson and Loke. The optimized arrays show significantly improved resolution over basic arrays adapted from traditional 2D surface geometries. Several MERIT case study surveys have been conducted in covered karst in west-central Florida, with

  19. Electrochemical detection of L-cysteine using a boron-doped carbon nanotube-modified electrode

    International Nuclear Information System (INIS)

    Deng Chunyan; Chen Jinhua; Chen Xiaoli; Wang Mengdong; Nie Zhou; Yao Shouzhuo

    2009-01-01

    A boron-doped carbon nanotube (BCNT)-modified glassy carbon (GC) electrode was constructed for the detection of L-cysteine (L-CySH). The electrochemical behavior of BCNTs in response to L-cysteine oxidation was investigated. The response current of L-CySH oxidation at the BCNT/GC electrode was obviously higher than that at the bare GC electrode or the CNT/GC electrode. This finding may be ascribed to the excellent electrochemical properties of the BCNT/GC electrode. Moreover, on the basis of this finding, a determination of L-CySH at the BCNT/GC electrode was carried out. The effects of pH, scan rate and interferents on the response of L-CySH oxidation were investigated. Under the optimum experimental conditions, the detection response for L-CySH on the BCNT/GC electrode was fast (within 7 s). It was found to be linear from 7.8 x 10 -7 to 2 x 10 -4 M (r = 0.998), with a high sensitivity of 25.3 ± 1.2 nA mM -1 and a low detection limit of 0.26 ± 0.01 μM. The BCNT/GC electrode exhibited high stability and good resistance against interference by other oxidizable amino acids (tryptophan and tyrosine)

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

    International Nuclear Information System (INIS)

    Song, Q.S.; Aravindaraj, G.K.; Sultana, H.; Chan, S.L.I.

    2007-01-01

    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

  1. A novel method of fabricating carbon nanotubes-polydimethylsiloxane composite electrodes for electrocardiography.

    Science.gov (United States)

    Liu, Benyan; Chen, Yingmin; Luo, Zhangyuan; Zhang, Wenzan; Tu, Quan; Jin, Xun

    2015-01-01

    Polymer-based flexible electrodes are receiving much attention in medical applications due to their good wearing comfort. The current fabrication methods of such electrodes are not widely applied. In this study, polydimethylsiloxane (PDMS) and conductive additives of carbon nanotubes (CNTs) were employed to fabricate composite electrodes for electrocardiography (ECG). A three-step dispersion process consisting of ultrasonication, stirring, and in situ polymerization was developed to yield homogenous CNTs-PDMS mixtures. The CNTs-PDMS mixtures were used to fabricate CNTs-PDMS composite electrodes by replica technology. The influence of ultrasonication time and CNT concentration on polymer electrode performance was evaluated by impedance and ECG measurements. The signal amplitude of the electrodes prepared using an ultrasonication time of 12 h and CNT content of 5 wt% was comparable to that of commercial Ag/AgCl electrodes. The polymer electrodes were easily fabricated by conventional manufacturing techniques, indicating a potential advantage of reduced cost for mass production.

  2. Vanadium oxide nanowire-carbon nanotube binder-free flexible electrodes for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Perera, Sanjaya D.; Patel, Bijal; Seitz, Oliver; Ferraris, John P.; Balkus, Kenneth J. Jr. [Department of Chemistry and the Alan G. MacDiarmid Nanotech Institute, 800 West Campbell Rd, University of Texas at Dallas, Richardson, TX 75080 (United States); Nijem, Nour; Roodenko, Katy; Chabal, Yves J. [Laboratory for Surface and Nanostructure Modification, Department of Material Science and Engineering, 800 West Campbell Rd, University of Texas Dallas, Richardson, TX 75080 (United States)

    2011-10-15

    Vanadium pentoxide (V{sub 2}O{sub 5}) layered nanostructures are known to have very stable crystal structures and high faradaic activity. The low electronic conductivity of V{sub 2}O{sub 5} greatly limits the application of vanadium oxide as electrode materials and requires combining with conducting materials using binders. It is well known that the organic binders can degrade the overall performance of electrode materials and need carefully controlled compositions. In this study, we develop a simple method for preparing freestanding carbon nanotube (CNT)-V{sub 2}O{sub 5} nanowire (VNW) composite paper electrodes without using binders. Coin cell type (CR2032) supercapacitors are assembled using the nanocomposite paper electrode as the anode and high surface area carbon fiber electrode (Spectracarb 2225) as the cathode. The supercapacitor with CNT-VNW composite paper electrode exhibits a power density of 5.26 kW Kg{sup -1} and an energy density of 46.3 Wh Kg{sup -1}. (Li)VNWs and CNT composite paper electrodes can be fabricated in similar manner and show improved overall performance with a power density of 8.32 kW Kg{sup -1} and an energy density of 65.9 Wh Kg{sup -1}. The power and energy density values suggest that such flexible hybrid nanocomposite paper electrodes may be useful for high performance electrochemical supercapacitors. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

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

    International Nuclear Information System (INIS)

    Yang Miaomiao; Cheng Bin; Song Huaihe; Chen Xiaohong

    2010-01-01

    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 o C 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Yang Miaomiao; Cheng Bin [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Song Huaihe, E-mail: songhh@mail.buct.edu.c [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Chen Xiaohong [State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)

    2010-09-30

    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 {sup o}C exhibit high specific capacitance of 163 F g{sup -1} at a current density of 0.1 A g{sup -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.

  5. Graphene and carbon nanotube composite electrodes for supercapacitors with ultra-high energy density.

    Science.gov (United States)

    Cheng, Qian; Tang, Jie; Ma, Jun; Zhang, Han; Shinya, Norio; Qin, Lu-Chang

    2011-10-21

    We describe a graphene and single-walled carbon nanotube (SWCNT) composite film prepared by a blending process for use as electrodes in high energy density supercapacitors. Specific capacitances of 290.6 F g(-1) and 201.0 F g(-1) have been obtained for a single electrode in aqueous and organic electrolytes, respectively, using a more practical two-electrode testing system. In the organic electrolyte the energy density reached 62.8 Wh kg(-1) and the power density reached 58.5 kW kg(-1). The addition of single-walled carbon nanotubes raised the energy density by 23% and power density by 31% more than the graphene electrodes. The graphene/CNT electrodes exhibited an ultra-high energy density of 155.6 Wh kg(-1) in ionic liquid at room temperature. In addition, the specific capacitance increased by 29% after 1000 cycles in ionic liquid, indicating their excellent cyclicity. The SWCNTs acted as a conductive additive, spacer, and binder in the graphene/CNT supercapacitors. This work suggests that our graphene/CNT supercapacitors can be comparable to NiMH batteries in performance and are promising for applications in hybrid vehicles and electric vehicles. This journal is © the Owner Societies 2011

  6. Carbon Nanotube Web with Carboxylated Polythiophene "Assist" for High-Performance Battery Electrodes.

    Science.gov (United States)

    Kwon, Yo Han; Park, Jung Jin; Housel, Lisa M; Minnici, Krysten; Zhang, Guoyan; Lee, Sujin R; Lee, Seung Woo; Chen, Zhongming; Noda, Suguru; Takeuchi, Esther S; Takeuchi, Kenneth J; Marschilok, Amy C; Reichmanis, Elsa

    2018-04-24

    A carbon nanotube (CNT) web electrode comprising magnetite spheres and few-walled carbon nanotubes (FWNTs) linked by the carboxylated conjugated polymer, poly[3-(potassium-4-butanoate) thiophene] (PPBT), was designed to demonstrate benefits derived from the rational consideration of electron/ion transport coupled with the surface chemistry of the electrode materials components. To maximize transport properties, the approach introduces monodispersed spherical Fe 3 O 4 (sFe 3 O 4 ) for uniform Li + diffusion and a FWNT web electrode frame that affords characteristics of long-ranged electronic pathways and porous networks. The sFe 3 O 4 particles were used as a model high-capacity energy active material, owing to their well-defined chemistry with surface hydroxyl (-OH) functionalities that provide for facile detection of molecular interactions. PPBT, having a π-conjugated backbone and alkyl side chains substituted with carboxylate moieties, interacted with the FWNT π-electron-rich and hydroxylated sFe 3 O 4 surfaces, which enabled the formation of effective electrical bridges between the respective components, contributing to efficient electron transport and electrode stability. To further induce interactions between PPBT and the metal hydroxide surface, polyethylene glycol was coated onto the sFe 3 O 4 particles, allowing for facile materials dispersion and connectivity. Additionally, the introduction of carbon particles into the web electrode minimized sFe 3 O 4 aggregation and afforded more porous FWNT networks. As a consequence, the design of composite electrodes with rigorous consideration of specific molecular interactions induced by the surface chemistries favorably influenced electrochemical kinetics and electrode resistance, which afforded high-performance electrodes for battery applications.

  7. Performance of Solution Processed Carbon Nanotube Field Effect Transistors with Graphene Electrodes

    OpenAIRE

    Gangavarapu, P R Yasasvi; Lokesh, Punith Chikkahalli; Bhat, K N; Naik, A K

    2016-01-01

    This work evaluates the performance of carbon nanotube field effect transistors (CNTFET) using few layer graphene as the contact electrode material. We present the experimental results obtained on the barrier height at CNT graphene junction using temperature dependent IV measurements. The estimated barrier height in our devices for both holes and electrons is close to zero or slightly negative indicating the Ohmic contact of graphene with the valence and conduction bands of CNTs. In addition,...

  8. Electric Double-Layer Capacitor Fabricated with Addition of Carbon Nanotube to Polarizable Electrode

    OpenAIRE

    Yoshiyuki Show

    2012-01-01

    Electrical double-layer capacitor (EDLC) was fabricated with addition of carbon nanotube (CNT) to polarization electrodes as a conducting material. The CNT addition reduced the series resistance of the EDLC by one-twentieth, while the capacitance was not increased by the CNT addition. The low series resistance leaded to the high electrical energy stored in the EDLC. In this paper, the dependence of the series resistance, the specific capacitance, the energy, and the energy efficiencies on the...

  9. Flexible, transparent single-walled carbon nanotube transistors with graphene electrodes

    International Nuclear Information System (INIS)

    Jang, Sukjae; Jang, Houk; Lee, Youngbin; Suh, Daewoo; Baik, Seunghyun; Hong, Byung Hee; Ahn, Jong-Hyun

    2010-01-01

    This paper reports a mechanically flexible, transparent thin film transistor that uses graphene as a conducting electrode and single-walled carbon nanotubes (SWNTs) as a semiconducting channel. These SWNTs and graphene films were printed on flexible plastic substrates using a printing method. The resulting devices exhibited a mobility of ∼ 2 cm 2 V -1 s -1 , On/Off ratio of ∼ 10 2 , transmittance of ∼ 81% and excellent mechanical bendability.

  10. Flexible, transparent single-walled carbon nanotube transistors with graphene electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Jang, Sukjae; Jang, Houk; Lee, Youngbin; Suh, Daewoo; Baik, Seunghyun; Hong, Byung Hee; Ahn, Jong-Hyun, E-mail: ahnj@skku.edu, E-mail: byunghee@skku.edu [SKKU Advanced Institute of Nanotechnology (SAINT) and Center for Human Interface Nano Technology (HINT), Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2010-10-22

    This paper reports a mechanically flexible, transparent thin film transistor that uses graphene as a conducting electrode and single-walled carbon nanotubes (SWNTs) as a semiconducting channel. These SWNTs and graphene films were printed on flexible plastic substrates using a printing method. The resulting devices exhibited a mobility of {approx} 2 cm{sup 2} V{sup -1} s{sup -1}, On/Off ratio of {approx} 10{sup 2}, transmittance of {approx} 81% and excellent mechanical bendability.

  11. Laser-Assisted Simultaneous Transfer and Patterning of Vertically Aligned Carbon Nanotube Arrays on Polymer Substrates for Flexible Devices

    KAUST Repository

    In, Jung Bin

    2012-09-25

    We demonstrate a laser-assisted dry transfer technique for assembling patterns of vertically aligned carbon nanotube arrays on a flexible polymeric substrate. A laser beam is applied to the interface of a nanotube array and a polycarbonate sheet in contact with one another. The absorbed laser heat promotes nanotube adhesion to the polymer in the irradiated regions and enables selective pattern transfer. A combination of the thermal transfer mechanism with rapid direct writing capability of focused laser beam irradiation allows us to achieve simultaneous material transfer and direct micropatterning in a single processing step. Furthermore, we demonstrate that malleability of the nanotube arrays transferred onto a flexible substrate enables post-transfer tailoring of electric conductance by collapsing the aligned nanotubes in different directions. This work suggests that the laser-assisted transfer technique provides an efficient route to using vertically aligned nanotubes as conductive elements in flexible device applications. © 2012 American Chemical Society.

  12. Laser-assisted simultaneous transfer and patterning of vertically aligned carbon nanotube arrays on polymer substrates for flexible devices.

    Science.gov (United States)

    In, Jung Bin; Lee, Daeho; Fornasiero, Francesco; Noy, Aleksandr; Grigoropoulos, Costas P

    2012-09-25

    We demonstrate a laser-assisted dry transfer technique for assembling patterns of vertically aligned carbon nanotube arrays on a flexible polymeric substrate. A laser beam is applied to the interface of a nanotube array and a polycarbonate sheet in contact with one another. The absorbed laser heat promotes nanotube adhesion to the polymer in the irradiated regions and enables selective pattern transfer. A combination of the thermal transfer mechanism with rapid direct writing capability of focused laser beam irradiation allows us to achieve simultaneous material transfer and direct micropatterning in a single processing step. Furthermore, we demonstrate that malleability of the nanotube arrays transferred onto a flexible substrate enables post-transfer tailoring of electric conductance by collapsing the aligned nanotubes in different directions. This work suggests that the laser-assisted transfer technique provides an efficient route to using vertically aligned nanotubes as conductive elements in flexible device applications.

  13. Growth of vertically aligned arrays of carbon nanotubes for high field emission

    International Nuclear Information System (INIS)

    Kim, D.; Lim, S.H.; Guilley, A.J.; Cojocaru, C.S.; Bouree, J.E.; Vila, L.; Ryu, J.H.; Park, K.C.; Jang, J.

    2008-01-01

    Vertically aligned multi-walled carbon nanotubes have been grown on Ni-coated silicon substrates, by using either direct current diode or triode plasma-enhanced chemical vapor deposition at low temperature (around 620 deg. C). Acetylene gas has been used as the carbon source while ammonia and hydrogen have been used for etching. However densely packed (∼ 10 9 cm -2 ) CNTs were obtained when the pressure was ∼ 100 Pa. The alignment of nanotubes is a necessary, but not a sufficient condition in order to get an efficient electron emission: the growth of nanotubes should be controlled along regular arrays, in order to minimize the electrostatic interactions between them. So a three dimensional numerical simulation has been developed to calculate the local electric field in the vicinity of the tips for a finite square array of nanotubes and thus to calculate the maximum of the electron emission current density as a function of the spacing between nanotubes. Finally the triode plasma-enhanced process combined with pre-patterned catalyst films (using different lithography techniques) has been chosen in order to grow regular arrays of aligned CNTs with different pitches in the micrometer range. The comparison between the experimental and the simulation data permits to define the most efficient CNT-based electron field emitters

  14. Fabrication of doped TiO2 nanotube array films with enhanced photo-catalytic activity

    Science.gov (United States)

    Peighambardoust, Naeimeh-Sadat; Khameneh-asl, Shahin; Khademi, Adib

    2018-01-01

    In the present work, we investigate the N and Fe-doped TiO2 nanotube array film prepared by treating TiO2 nanotube array film with ammonia solution and anodizing in Fe(NO3)3 solution respectively. This method avoided the use of hazardous ammonia gas, or laborious ion implantation process. N and Fe-doped TiO2 nanotube arrays (TiO2 NTs) were prepared by electrochemical anodization process in 0.5 wt % HF aqueous solution. The anodization was performed at the conditions of 20 V and 20 min, Followed by a wet immersion in NH3.H2O (1M) for N-doping for 2 hr and annealing post-treatment at 450 °C. The morphology and structure of the nanotube films were characterized by field emission scanning electron microscope (FESEM) and EDX. UV-vis. illumination test were done to observe photo-enhanced catalysis. The effect of different annealing temperature on the structure and photo-absorption property of the TiO2-TNTs was investigated. The results showed that N-TNTs nanotubes exhibited higher photocatalytic activity compared whit the Fe-doped and pure TNTs, because doping N promoted the separation of the photogenerated electrons and holes.

  15. P25 nanoparticles decorated on titania nanotubes arrays as effective drug delivery system for ibuprofen

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhang; Xie, Chunlin; Luo, Fei; Li, Ping; Xiao, Xiufeng, E-mail: xfxiao@fjnu.edu.cn

    2015-01-01

    Highlights: • P25 nanoparticles decorated on titania nanotube arrays were prepared by hydrothermal treatment. • P25 nanoparticles were conducive to improve the loading effect of ibuprofen into nanotube arrays. • The diameters of the decorated nanotubes were decrease markedly which led to an effective and prolonged drug release. - Abstract: In this study, uniformly distributed layer of P25 nanoparticles (NPs) decorated on titania (TiO{sub 2}) nanotubes (TNTs) arrays was prepared in a teflon-lined stainless steel autoclave by the hydrothermal treatment. To investigate the influence of the P25 concentration, different concentrations of P25 NPs were added into the solution to obtain the optimal decorative effect. TNTs decorated with P25 (TNTs–P25) and TNTs without P25 decorated on its surface were loaded with ibuprofen (IBU) via vacuum drying and its release properties were investigated. The samples were characterized by field emission scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The results indicated that P25 NPs were successfully decorated on the surface of TNTs by hydrothermal method and the optimal concentration was found to be 7.5 × 10{sup −4} M. P25 NPs decorated on TNTs led to a significant increase in the specific surface area of TNTs which was conducive to improve the loading effect of IBU. Importantly, the diameters of the decorated nanotubes were reduced to 100 ± 10 nm and the increase in roughness led to an effective and prolonged drug release.

  16. Guided proliferation and bone-forming functionality on highly ordered large diameter TiO2 nanotube arrays

    International Nuclear Information System (INIS)

    Zhang, Ruopeng; Wu, Hongliu; Ni, Jiahua; Zhao, Changli; Chen, Yifan; Zheng, Chengjunyi; Zhang, Xiaonong

    2015-01-01

    The significantly enhanced osteoblast adhesion, proliferation and alkaline phosphatase (ALP) activity were observed on TiO 2 nanotube surface in recent studies in which the scale of nanotube diameter was restricted under 100 nm. In this paper, a series of highly ordered TiO 2 nanotube arrays with larger diameters ranging from 150 nm to 470 nm were fabricated via high voltage anodization. The behaviors of MC3T3-E1 cells in response to the diameter-controlled TiO 2 nanotubes were investigated. A contrast between the trend of proliferation and the trend of cell elongation was observed. The highest cell elongation (nearly 10:1) and the lowest cell number were observed on the TiO 2 nanotube arrays with 150 nm diameter. While, the lowest cell elongation and highest cell number were achieved on the TiO 2 nanotube arrays with 470 nm diameter. Furthermore, the ALP activity peaked on the 150 nm diameter TiO 2 nanotube arrays and decreased dramatically with the increase of nanotube diameter. Thus a narrow range of diameter (100–200 nm) that could induce the greatest bone-forming activity is determined. It is expected that more delicate design of orthopedic implant with regional abduction of cell proliferation or bone forming could be achieved by controlling the diameter of TiO 2 nanotubes. - Highlights: • Improved anodization methods leading to more ordered large diameter TiO 2 nanotubes • Significantly enhanced ALP activity was observed on 150 nm diameter TiO 2 nanotubes. • The highest cell density was observed on 470 nm diameter TiO 2 nanotube arrays. • Similar cell response was observed on the amorphous and anatase phased nanotube surface

  17. Direct growth of vanadium nitride nanosheets on carbon nanotube fibers as novel negative electrodes for high-energy-density wearable fiber-shaped asymmetric supercapacitors

    Science.gov (United States)

    Guo, Jiabin; Zhang, Qichong; Sun, Juan; Li, Chaowei; Zhao, Jingxin; Zhou, Zhenyu; He, Bing; Wang, Xiaona; Man, Ping; Li, Qiulong; Zhang, Jun; Xie, Liyan; Li, Mingxing; Yao, Yagang

    2018-04-01

    Significant efforts have been recently devoted to constructing high-performance fiber-shaped asymmetric supercapacitors. However, it is still a paramount challenge to develop high-energy-density fiber-shaped asymmetric supercapacitors for practical applications in portable and wearable electronics. This work reports a simple and efficient method to directly grow vanadium nitride nanosheets on carbon nanotube fibers as advanced negative electrodes with a high specific capacitance of 188 F/cm3 (564 mF/cm2). Taking advantage of their attractive structure, we successfully fabricated a fiber-shaped asymmetric supercapacitor device with a maximum operating voltage of 1.6 V by assembling the vanadium nitride/carbon nanotube fiber negative electrode with the Zinc-Nickel-Cobalt ternary oxides nanowire arrays positive electrode. Due to the excellent synergistic effects between positive and negative electrodes, a remarkable specific capacitance of 50 F/cm3 (150 mF/cm2) and an outstanding energy density of 17.78 mWh/cm3 (53.33 μWh/cm2) for our fiber-shaped asymmetric supercapacitor can be achieved. Furthermore, the as-assembled fiber-shaped asymmetric supercapacitor device has excellent mechanical flexibility in that 91% of the capacitance retained after bending 90° for 3000 times. Thus, this work exploits a pathway to construct high-energy-density fiber-shaped asymmetric supercapacitor for next-generation portable and wearable electronics.

  18. Transmission properties of terahertz waves through asymmetric rectangular aperture arrays on carbon nanotube films

    Directory of Open Access Journals (Sweden)

    Yue Wang

    2016-04-01

    Full Text Available Transmission spectra of terahertz waves through a two-dimensional array of asymmetric rectangular apertures on super-aligned multi-walled carbon nanotube films were obtained experimentally. In this way, the anisotropic transmission phenomena of carbon nanotube films were observed. For a terahertz wave polarization parallel to the orientation of the carbon nanotubes and along the aperture short axis, sharp resonances were observed and the resonance frequencies coincided well with the surface plasmon polariton theory. In addition, the minima of the transmission spectra were in agreement with the location predicted by the theory of Wood’s anomalies. Furthermore, it was found that the resonance profiles through the carbon nanotube films could be well described by the Fano model.

  19. Vertically Aligned Carbon Nanotube Array (VANTA Biosensor for MEMS Lab-on-a-Chip

    Directory of Open Access Journals (Sweden)

    Luke JOSEPH

    2009-10-01

    Full Text Available We describe the fabrication, functionalization and characterization of vertically aligned carbon nanotube arrays (VANTAs for biological sensor applications. This structure is created using a standard MEMS process and chemical vapor deposition (CVD multi-walled carbon nanotube (MWNT post-processing. The device is well suited for full integration into microfluidic lab-on-a-chip solutions. Included is a spectroscopic characterization of the galvanostatic impedance of the device, as well as scanning electron microscopy (SEM images of the pre- and post- functionalized device. Interferometric 3D profiling and X-ray spectroscopy were also used to check process assumptions. The work presented validates that this approach is an ideal candidate for low-cost, high-throughput manufacturing of biochemical sensors. Unlike previously published work [1, 2] using SWNT, the use of MWNT arrays allows functionalization over the entirety of the nanotubes. This approach maintains low baseline impedance and increases the surface area leveraging inherent benefits of the VANTA.

  20. Propagation of three-dimensional bipolar ultrashort electromagnetic pulses in an inhomogeneous array of carbon nanotubes

    Science.gov (United States)

    Fedorov, Eduard G.; Zhukov, Alexander V.; Bouffanais, Roland; Timashkov, Alexander P.; Malomed, Boris A.; Leblond, Hervé; Mihalache, Dumitru; Rosanov, Nikolay N.; Belonenko, Mikhail B.

    2018-04-01

    We study the propagation of three-dimensional (3D) bipolar ultrashort electromagnetic pulses in an inhomogeneous array of semiconductor carbon nanotubes. The heterogeneity is represented by a planar region with an increased concentration of conduction electrons. The evolution of the electromagnetic field and electron concentration in the sample are governed by the Maxwell's equations and continuity equation. In particular, nonuniformity of the electromagnetic field along the axis of the nanotubes is taken into account. We demonstrate that depending on values of the parameters of the electromagnetic pulse approaching the region with the higher electron concentration, the pulse is either reflected from the region or passes it. Specifically, our simulations demonstrate that after interacting with the higher-concentration area, the pulse can propagate steadily, without significant spreading. The possibility of such ultrashort electromagnetic pulses propagating in arrays of carbon nanotubes over distances significantly exceeding characteristic dimensions of the pulses makes it possible to consider them as 3D solitons.

  1. Photocatalytic methane decomposition over vertically aligned transparent TiO2 nanotube arrays

    DEFF Research Database (Denmark)

    In, Su-il; Nielsen, Morten Godtfred; Vesborg, Peter Christian Kjærgaard

    2011-01-01

    Vertically aligned transparent TiO2 nanotube arrays grown by the one-step anodic oxidation technique (on non-conductive supports such as Pyrex) and their photocatalytic performance for methane decomposition in a single-pass micro-fabricated reactor under UV light....

  2. Fabrication of Arrays of Metal and Metal Oxide Nanotubes by Shadow Evaporation

    NARCIS (Netherlands)

    Dickey, Michael D.; Weiss, Emily A.; Smythe, Elizabeth J.; Chiechi, Ryan C.; Capasso, Federico; Whitesides, George M.

    2008-01-01

    This paper describes a simple technique for fabricating uniform arrays of metal and metal oxide nanotubes with controlled heights and diameters. The technique involves depositing material onto an anodized aluminum oxide (AAO) membrane template using a collimated electron beam evaporation source. The

  3. Towards ultrathick battery electrodes: aligned carbon nanotube - enabled architecture

    Energy Technology Data Exchange (ETDEWEB)

    Evanoff, Kara [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA (United States); Electro-Optical Systems Laboratory, Georgia Tech Research Institute, Atlanta, GA (United States); Khan, Javed; Balandin, Alexander A. [Department of Electrical Engineering, University of California, Riverside, CA (United States); Magasinski, Alexandre; Yushin, Gleb [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA (United States); Ready, W. Jud [Electro-Optical Systems Laboratory, Georgia Tech Research Institute, Atlanta, GA (United States); Fuller, Thomas F. [School of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA (United States)

    2012-01-24

    Vapor deposition techniques were utilized to synthesize very thick ({proportional_to}1 mm) Li-ion battery anodes consisting of vertically aligned carbon nanotubes coated with silicon and carbon. The produced anode demonstrated ultrahigh thermal (>400 W.m{sup -1}.K{sup -1}) and high electrical (>20 S.m{sup -1}) conductivities, high cycle stability, and high average capacity (>3000 mAh.g{sub Si}{sup -1}). The processes utilized allow for the conformal deposition of other materials, thus making it a promising architecture for the development of Li-ion anodes and cathodes with greatly enhanced electrical and thermal conductivities. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Capacitive performance of molybdenum nitride/titanium nitride nanotube array for supercapacitor

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Yibing, E-mail: ybxie@seu.edu.cn; Tian, Fang

    2017-01-15

    Highlights: • MoN{sub x}/TiN NTA is fully converted from MoO{sub 2}/TiO{sub 2} NTA by one-step nitridation process. • MoN{sub x}/TiN NTA is used as feasible electrode material of high-performance supercapacitor. • MoN{sub x}/TiN NTA shows high capacitance, rate capability and cycling stability. - Abstract: Molybdenum nitride (MoN{sub x}) depositing on titanium nitride nanotube array (TiN NTA) was designed as MoN{sub x}/TiN NTA for supercapacitor electrode material. MoN{sub x}/TiN NTA was fabricated by electrodepositing molybdenum oxide onto titanium dioxide NTA and one-step nitridation treatment in ammonia. MoN{sub x}/TiN NTA involved top-surface layer of MoN{sub x} nanoparticles and underlying layer of TiN NTA, which contributed to electric double layer capacitance in aqueous lithium-ion electrolyte solution. The specific capacitance was increased from 69.05 mF cm{sup −2} for TiN NTA to 121.50 mF cm{sup −2} for MoN{sub x}/TiN NTA at 0.3 mA cm{sup −2}, presenting the improved capacitance performance. MoN{sub x} exhibited the capacitance of 174.83 F g{sup −1} at 1.5 A g{sup −1} and slightly declined to 109.13 F g{sup −1} at 30 A g{sup −1}, presenting high rate capability. MoN{sub x}/TiN NTA exhibited the capacitance retention ratio of 93.8% at 3.0 mA cm{sup −2} after 1000 cycles, presenting high cycling stability. MoN{sub x}/TiN NTA could act as a promising electrode material of supercapacitor.

  5. A Palladium-Tin Modified Microband Electrode Array for Nitrate Determination

    Directory of Open Access Journals (Sweden)

    Yexiang Fu

    2015-09-01

    Full Text Available A microband electrode array modified with palladium-tin bimetallic composite has been developed for nitrate determination. The microband electrode array was fabricated by Micro Electro-Mechanical System (MEMS technique. Palladium and tin were electrodeposited successively on the electrode, forming a double-layer structure. The effect of the Pd-Sn composite was investigated and its enhancement of catalytic activity and lifetime was revealed. The Pd-Sn modified electrode showed good linearity (R2 = 0.998 from 1 mg/L to 20 mg/L for nitrate determination with a sensitivity of 398 μA/(mg∙L−1∙cm2. The electrode exhibited a satisfying analytical performance after 60 days of storage, indicating a long lifetime. Good repeatability was also displayed by the Pd-Sn modified electrodes. The results provided an option for nitrate determination in water.

  6. A strategy for selective detection based on interferent depleting and redox cycling using the plane-recessed microdisk array electrodes

    International Nuclear Information System (INIS)

    Zhu Feng; Yan Jiawei; Lu Miao; Zhou Yongliang; Yang Yang; Mao Bingwei

    2011-01-01

    Highlights: → A novel strategy based on a combination of interferent depleting and redox cycling is proposed for the plane-recessed microdisk array electrodes. → The strategy break up the restriction of selectively detecting a species that exhibits reversible reaction in a mixture with one that exhibits an irreversible reaction. → The electrodes enhance the current signal by redox cycling. → The electrodes can work regardless of the reversibility of interfering species. - Abstract: The fabrication, characterization and application of the plane-recessed microdisk array electrodes for selective detection are demonstrated. The electrodes, fabricated by lithographic microfabrication technology, are composed of a planar film electrode and a 32 x 32 recessed microdisk array electrode. Different from commonly used redox cycling operating mode for array configurations such as interdigitated array electrodes, a novel strategy based on a combination of interferent depleting and redox cycling is proposed for the electrodes with an appropriate configuration. The planar film electrode (the plane electrode) is used to deplete the interferent in the diffusion layer. The recessed microdisk array electrode (the microdisk array), locating within the diffusion layer of the plane electrode, works for detecting the target analyte in the interferent-depleted diffusion layer. In addition, the microdisk array overcomes the disadvantage of low current signal for a single microelectrode. Moreover, the current signal of the target analyte that undergoes reversible electron transfer can be enhanced due to the redox cycling between the plane electrode and the microdisk array. Based on the above working principle, the plane-recessed microdisk array electrodes break up the restriction of selectively detecting a species that exhibits reversible reaction in a mixture with one that exhibits an irreversible reaction, which is a limitation of single redox cycling operating mode. The

  7. A tripolar-electrode ionization gas sensor using a carbon nanotube cathode for NO detection

    Science.gov (United States)

    Song, Hui; Li, Kun; Li, Quanfu

    2018-06-01

    Nitric oxide accounts for more than 95% of the total NO X emission from power plants, which is a major air pollutant. Therefore, it is imperative to accurately detect NO for environmental protection. A tripolar-electrode ionization sensor with a carbon nanotube (CNT) cathode is proposed for NO detection. The non-self-sustaining discharge state and the tripolar-electrode configuration ensures a long nanotube life, which ensures a good stability and fast response of the sensor. Experimental results demonstrate that the tripolar-electrode ionization sensor with 120 µm separations has an intrinsic monotonously decreasing response to NO and exhibits a fast response time of 7 s and recovery time of 8 s. More consumption of the two metastable states N2(A3  ∑  u +) and N2(aʹ1  ∑  u +) of N2 with the increasing of NO concentration is responsible for this. The tripolar-electrode ionization sensor also shows excellent long-term stability of at least one month due to the long CNT life. In addition, the weak effect of SO2 introduction on NO response indicates a good selectivity of the sensor to NO.

  8. Solid-contact pH-selective electrode using multi-walled carbon nanotubes.

    Science.gov (United States)

    Crespo, Gastón A; Gugsa, Derese; Macho, Santiago; Rius, F Xavier

    2009-12-01

    Multi-walled carbon nanotubes (MWCNT) are shown to be efficient transducers of the ionic-to-electronic current. This enables the development of a new solid-contact pH-selective electrode that is based on the deposition of a 35-microm thick layer of MWCNT between the acrylic ion-selective membrane and the glassy carbon rod used as the electrical conductor. The ion-selective membrane was prepared by incorporating tridodecylamine as the ionophore, potassium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate as the lipophilic additive in a polymerized methylmethacrylate and an n-butyl acrylate matrix. The potentiometric response shows Nernstian behaviour and a linear dynamic range between 2.89 and 9.90 pH values. The response time for this electrode was less than 10 s throughout the whole working range. The electrode shows a high selectivity towards interfering ions. Electrochemical impedance spectroscopy and chronopotentiometry techniques were used to characterise the electrochemical behaviour and the stability of the carbon-nanotube-based ion-selective electrodes.

  9. When Al-Doped Cobalt Sulfide Nanosheets Meet Nickel Nanotube Arrays: A Highly Efficient and Stable Cathode for Asymmetric Supercapacitors.

    Science.gov (United States)

    Huang, Jun; Wei, Junchao; Xiao, Yingbo; Xu, Yazhou; Xiao, Yujuan; Wang, Ying; Tan, Licheng; Yuan, Kai; Chen, Yiwang

    2018-03-27

    Although cobalt sulfide is a promising electrode material for supercapacitors, its wide application is limited by relative poor electrochemical performance, low electrical conductivity, and inefficient nanostructure. Here, we demonstrated that the electrochemical activity of cobalt sulfide could be significantly improved by Al doping. We designed and fabricated hierarchical core-branch Al-doped cobalt sulfide nanosheets anchored on Ni nanotube arrays combined with carbon cloth (denoted as CC/H-Ni@Al-Co-S) as an excellent self-standing cathode for asymmetric supercapacitors (ASCs). The combination of structural and compositional advantages endows the CC/H-Ni@Al-Co-S electrode with superior electrochemical performance with high specific capacitance (1830 F g -1 /2434 F g -1 at 5 mV s -1 /1 A g -1 ) and excellent rate capability (57.2%/72.3% retention at 1000 mV s -1 /100 A g -1 ). The corresponding all-solid-state ASCs with CC/H-Ni@Al-Co-S and multilayer graphene/CNT film as cathode and anode, respectively, achieve a high energy density up to 65.7 W h kg -1 as well as superb cycling stability (90.6% retention after 10 000 cycles). Moreover, the ASCs also exhibit good flexibility and stability under different bending conditions. This work provides a general, effective route to prepare high-performance electrode materials for flexible all-solid-state energy storage devices.

  10. Investigation of Implantable Multi-Channel Electrode Array in Rat Cerebral Cortex Used for Recording

    Science.gov (United States)

    Taniguchi, Noriyuki; Fukayama, Osamu; Suzuki, Takafumi; Mabuchi, Kunihiko

    There have recently been many studies concerning the control of robot movements using neural signals recorded from the brain (usually called the Brain-Machine interface (BMI)). We fabricated implantable multi-electrode arrays to obtain neural signals from the rat cerebral cortex. As any multi-electrode array should have electrode alignment that minimizes invasion, it is necessary to customize the recording site. We designed three types of 22-channel multi-electrode arrays, i.e., 1) wide, 2) three-layered, and 3) separate. The first extensively covers the cerebral cortex. The second has a length of 2 mm, which can cover the area of the primary motor cortex. The third array has a separate structure, which corresponds to the position of the forelimb and hindlimb areas of the primary motor cortex. These arrays were implanted into the cerebral cortex of a rat. We estimated the walking speed from neural signals using our fabricated three-layered array to investigate its feasibility for BMI research. The neural signal of the rat and its walking speed were simultaneously recorded. The results revealed that evaluation using either the anterior electrode group or posterior group provided accurate estimates. However, two electrode groups around the center yielded poor estimates although it was possible to record neural signals.

  11. Cochlear pathology following reimplantation of a multichannel scala tympani electrode array in the macaque.

    Science.gov (United States)

    Shepherd, R K; Clark, G M; Xu, S A; Pyman, B C

    1995-03-01

    The histopathologic consequence of removing and reimplanting intracochlear electrode arrays on residual auditory nerve fibers is an important issue when evaluating the safety of cochlear prostheses. The authors have examined this issue by implanting multichannel intracochlear electrodes in macaque monkeys. Macaques were selected because of the similarity of the surgical technique used to insert electrodes into the cochlea compared to that in humans, in particular the ability to insert the arrays into the upper basal turn. Five macaques were bilaterally implanted with the Melbourne/Cochlear banded electrode array. Following a minimum implant period of 5 months, the electrode array on one side of each animal was removed and another immediately implanted. The animals were sacrificed a minimum of 5 months following the reinsertion procedure, and the cochleas prepared for histopathologic analysis. Long-term implantation of the electrode resulted in a relatively mild tissue response within the cochlea. Results also showed that inner and outer hair cell survival, although significantly reduced adjacent to the array, was normal in 8 of the 10 cochleas apicalward. Moreover, the electrode reinsertion procedure did not appear to adversely affect this apical hair cell population. Significant new bone formation was frequently observed in both control and reimplanted cochleas close to the electrode fenestration site and was associated with trauma to the endosteum and/or the introduction of bone chips into the cochlea at the time of surgery. Electrode insertion trauma, involving the osseous spiral lamina or basilar membrane, was more commonly observed in reimplanted cochleas. This damage was usually restricted to the lower basal turn and resulted in a more extensive ganglion cell loss. Finally, in a number of cochleas part of the electrode array was located within the scala media or scala vestibuli. These electrodes did not appear to evoke a more extensive tissue response or

  12. Organometal halide perovskite light-emitting diodes with laminated carbon nanotube electrodes

    Science.gov (United States)

    Shan, Xin; Bade, Sri Ganesh R.; Geske, Thomas; Davis, Melissa; Smith, Rachel; Yu, Zhibin

    2017-08-01

    Organometal halide perovskite light-emitting diodes (LEDs) with laminated carbon nanotube (CNT) electrodes are reported. The LEDs have an indium tin oxide (ITO) bottom electrode, a screen printed methylammonium lead tribromide (MAPbBr3)/polymer composite thin film as the emissive layer, and laminated CNT as the top electrode. The devices can be turned on at 2.2 V, reaching a brightness of 4,960 cd m-2 and a current efficiency of 1.54 cd A-1 at 6.9 V. The greatly simplified fabrication process in this work can potentially lead to the scalable manufacturing of large size and low cost LED panels in the future.

  13. Determination of serotonin on platinum electrode modified with carbon nanotubes/polypyrrole/silver nanoparticles nanohybrid.

    Science.gov (United States)

    Cesarino, Ivana; Galesco, Heloisa V; Machado, Sergio A S

    2014-07-01

    A new sensor has been developed by a simple electrodeposition of multi-walled carbon nanotubes (MWCNT), polypyrrole (PPy) and colloidal silver nanoparticles on the platinum (Pt) electrode surface. The Pt/MWCNT/PPy/AgNPs electrode was applied to the detection of serotonin in plasmatic serum samples using differential pulse voltammetry (DPV). The synergistic effect of MWCNT/PPy/AgNPs nanohybrid formed yielded a LOD of 0.15 μmol L(-1) (26.4 μg L(-1)). Reproducibility and repeatability values of 2.2% and 1.7%, respectively, were obtained compared to the conventional procedure. The proposed electrode can be an effective material to be used in biological analysis. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Sensitive detection of hydroxylamine at a simple baicalin carbon nanotubes modified electrode.

    Science.gov (United States)

    Zhang, Hongfang; Zheng, Jianbin

    2012-05-15

    A baicalin multi-wall carbon nanotubes (BaMWCNT) modified glassy carbon electrode (GCE) for the sensitive determination of hydroxylamine was described. The BaMWCNT/GCE with dramatic stability was firstly fabricated with a simple adsorption method. And it showed excellent catalytic activity toward the electrooxidation of hydroxylamine. The amperometric response at the BaMWCNT/GCE modified electrode increased linearly to hydroxylamine concentrations in the range of 0.5 μM to 0.4mM with a detection limit of 0.1 μM. The modified electrode was applied to detection hydroxylamine in the tap water, and the average recovery for the standards added was 96.0%. Copyright © 2012 Elsevier B.V. All rights reserved.

  15. Electrochemical selective detection of dopamine on microbial carbohydrate-doped multiwall carbon nanotube-modified electrodes.

    Science.gov (United States)

    Jin, Joon-Hyung; Cho, Eunae; Jung, Seunho

    2010-03-01

    Microbial carbohydrate-doped multiwall carbon nanotube (MWNT)-modified electrodes were prepared for the purpose of determining if 4-(2-aminoethyl)benzene-1,2-diol (3,4-dihydroxyphenylalanine; dopamine) exists in the presence of 0.5 mM ascorbic acid, a representative interfering agent in neurotransmitter detection. The microbial carbohydrate dopants were alpha-cyclosophorohexadecaose (alpha-C16) from Xanthomonas oryzae and cyclic-(1 --> 2)-beta-d-glucan (Cys) from Rhizobium meliloti. The cyclic voltammetric responses showed that the highest sensitivity (5.8 x 10(-3) mA cm(-2) microM(-1)) is attained with the Cys-doped MWNT-modified ultra-trace carbon electrode, and that the alpha-C16-doped MWNT-modified glassy carbon electrode displays the best selectivity to dopamine (the approximate peak potential separation is 310 mV).

  16. Electrochemical sensor for hazardous food colourant quinoline yellow based on carbon nanotube-modified electrode.

    Science.gov (United States)

    Zhao, Jun; Zhang, Yu; Wu, Kangbing; Chen, Jianwei; Zhou, Yikai

    2011-09-15

    A novel electrochemical method using multi-wall carbon nanotube (MWNT) film-modified electrode was developed for the detection of quinoline yellow. In pH 8 phosphate buffer, an irreversible oxidation peak at 0.71V was observed for quinoline yellow. Compared with the unmodified electrode, the MWNT film-modified electrode greatly increases the oxidation peak current of quinoline yellow, showing notable enhancement effect. The effects of pH value, amount of MWNT, accumulation potential and time were studied on the oxidation peak current of quinoline yellow. The linear range is from 0.75 to 20mgL(-1), and the limit of detection is 0.5mgL(-1). It was applied to the detection of quinoline yellow in commercial soft drinks, and the results consisted with the value that obtained by high-performance liquid chromatography. Copyright © 2011 Elsevier Ltd. All rights reserved.

  17. Electrochemical determination of cadmium and lead on pristine single-walled carbon nanotube electrodes.

    Science.gov (United States)

    Bui, Minh-Phuong Ngoc; Li, Cheng Ai; Han, Kwi Nam; Pham, Xuan-Hung; Seong, Gi Hun

    2012-01-01

    A flexible, transparent, single-walled carbon nanotube (SWCNT) film electrode was prepared by vacuum filtering methods, followed by photolithographic patterning of a photoresist polymer on the SWCNT surface. The morphology of the SWCNT film electrode surface was characterized using a field-emission scanning electron microscope coupled to an energy-dispersive X-ray spectrophotometer. The electrodes were successfully used as a mercury-free electrochemical sensor for individual and simultaneous detection of cadmium (Cd(2+)) and lead (Pb(2+)) in 0.02 M HCl by square-wave stripping voltammetry. Some important operational parameters, including deposition time, deposition potential, square-wave amplitude, and square wave-frequency were optimized for the detection of Cd(2+) and Pb(2+). The newly developed sensor showed good linear behavior in the examined concentration. For individual Cd(2+) and Pb(2+) ion detection, the linear range was found from 0.033 to 0.228 ppm with detection limits of 0.7 ppb (R(2) = 0.985) for Cd(2+) and 0.8 ppb (R(2) = 0.999) for Pb(2+). For simultaneous detection, the linear range was found from 0.033 to 0.280 ppm with a limit of detection of 2.2 ppb (R(2) = 0.976) and 0.6 ppb (R(2) = 0.996) for Cd(2+) and Pb(2+), respectively. SWCNT film electrodes offered favorable reproducibility of ± 5.4% and 4.3% for Cd(2+) and Pb(2+), respectively. The experiments demonstrated the applicability of carbon nanotubes, specifically in the preparation of SWCNT films. The results suggest that the proposed flexible SWCNT film electrodes can be applied as simple, efficient, cost-effective, and/or disposable electrodes for simultaneous detection of heavy metal ions.

  18. Preparation, characterization and simulation studies of carbon nanotube electrodes for electrochemical energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Meissner, Frank; Endler, Ingolf [Fraunhofer-Institut fuer Keramische Technologien und Systeme (IKTS), Dresden (Germany); Lorrmann, Henning [Fraunhofer-Institut fuer Silicatforschung (ISC), Wuerzburg (Germany); Pastewka, Lars [Fraunhofer-Institut fuer Werkstoffmechanik (IWM), Freiburg im Breisgau (Germany)

    2010-07-01

    Chemical Vapor Deposition (CVD) was employed to synthesize multiwalled carbon nanotubes (MWCNT) on different carrier materials for electrode applications. In the field of electrochemical energy storage it is essential to grow MWCNT on conducting substrates. For this reason titanium nitride (TiN) layers as well as a copper foil were used as substrates. The MWCNT grown on TiN layers show diameters of about 20 nm and lengths up to 13 {mu}m. In the case of copper foil substrates a remarkably higher nanotube diameter of several tens of nanometers was found. First electrochemical characterization via cyclic voltammetry shows the potential of MWCNT as electrodes for energy storage applications. The CNT were measured in an organic carbonate electrolyte vs. a lithium counter electrode with various scan rates. Until now the preliminary investigations by cyclic voltammetry for electrodes consisting of aligned MWCNT on TiN showed a capacity of around 130 F g{sup -1} in the range of 1 - 3 V vs. Li/Li{sup +}. In support of the experiments we construct a one dimensional Poisson-Nernst-Planck (PNP) continuum model that has been shown to yield agreement with corresponding molecular dynamics simulations to model ion transport into these types of electrodes. Our simulations show that first the ions accumulate at the tips of the tubes because the inner volume of the electrodes is initially field-free. A homogeneous charge distribution is then established through diffusion. The PNP model is used to compute cyclic voltammograms which show qualitative agreement with the experiments. (orig.)

  19. In-vitro bioactivity and electrochemical behavior of polyaniline encapsulated titania nanotube arrays for biomedical applications

    Science.gov (United States)

    Agilan, P.; Rajendran, N.

    2018-05-01

    Titania nanotube arrays (TNTA) have attracted increasing attention due to their outstanding properties and potential applications in biomedical field. Fabrication of titania nanotubes on titanium surface enhances the biocompatibility. Polyaniline (PANI) is one of the best conducting polymers with remarkable corrosion resistance and reasonable biocompatibility. In this work, the corrosion resistance and biocompatibility of polyaniline encapsulated TiO2 nanotubes for orthopaedic applications were investigated. The vertically oriented, highly ordered TiO2 nanotubes were fabricated on titanium by electrochemical anodization process using fluoride containing electrolytes. The anodization parameters viz., voltage, pH, time and electrolyte concentration were optimized to get orderly arranged TNTA. Further, the conducting polymer PANI was encapsulated on TNTA by electropolymerization process to enhance the corrosion resistance. The nanostructure of the fabricated TNTA and polyaniline encapsulated titania nanotube arrays (PANI-TNTA) were investigated by HR SEM analysis. The formed phases and functional groups were find using XRD, ATR-FTIR. The hydrophilic surface of TNTA and PANI-TNTA was identified by water contact angle studies. The corrosion behavior of specimens was evaluated by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization studies. In-vitro immersion studies were carried out in simulated body fluid solution (Hanks' solution) to evaluate the bioactivity of the TNTA and PANI-TNTA. The surface morphological studies revealed the formation of PANI on the TNTA surface. Formation of hydroxyapatite (HAp) on the surfaces of TNTA and PANI-TNTA enhanced the bioactivity and corrosion resistance.

  20. Optical properties of TiO2 nanotube arrays fabricated by the electrochemical anodization method

    International Nuclear Information System (INIS)

    Ly, Ngoc Tai; Nguyen, Van Chien; Dao, Thi Hoa; Hoang To, Le Hong; Pham, Duy Long; Do, Hung Manh; Vu, Dinh Lam; Le, Van Hong

    2014-01-01

    Perpendicularly self-aligned TiO 2 nanotube samples of size of 3 × 5 cm 2 were fabricated by the electrochemical anodization method using a solution containing NH 4 F. Influences of the technological conditions such as NH 4 F concentration and anodization voltage were studied. It was found that NH 4 F concentration in the solution and anodization voltage significantly affect the diameter and length of a TiO 2 nanotube. The diameter and the length of a TiO 2 nanotube were observed and estimated by using scanning electron microscopy. It has shown that the largest diameter and the longest length of about 80 nm and 20 μm, respectively, were obtained for the sample anodized in a solution containing 0.4% of NH 4 F, under a voltage of 48 V. Photoluminescence spectra excited by laser lights having wavelengths of 325 and 442 nm (having energies higher and lower than the band gap energy of TiO 2 ) was recorded at room temperature for the TiO 2 nanotube arrays. An abnormal luminescence result was observed. It is experimental evidence that the manufactured TiO 2 nanotube array is an expected material for hydrogen splitting from water by photochemical effect under sunlight as well as for the nano solar cells. (paper)

  1. Ag2S/CdS/TiO2 Nanotube Array Films with High Photocurrent Density by Spotting Sample Method

    OpenAIRE

    Sun, Hong; Zhao, Peini; Zhang, Fanjun; Liu, Yuliang; Hao, Jingcheng

    2015-01-01

    Ag2S/CdS/TiO2 hybrid nanotube array films (Ag2S/CdS/TNTs) were prepared by selectively depositing a narrow-gap semiconductor—Ag2S (0.9 eV) quantum dots (QDs)—in the local domain of the CdS/TiO2 nanotube array films by spotting sample method (SSM). The improvement of sunlight absorption ability and photocurrent density of titanium dioxide (TiO2) nanotube array films (TNTs) which were obtained by anodic oxidation method was realized because of modifying semiconductor QDs. The CdS/TNTs, Ag2S/TNT...

  2. In situ growth of NiCo2S4 nanotube arrays on Ni foam for supercapacitors: Maximizing utilization efficiency at high mass loading to achieve ultrahigh areal pseudocapacitance

    Science.gov (United States)

    Chen, Haichao; Jiang, Jianjun; Zhang, Li; Xia, Dandan; Zhao, Yuandong; Guo, Danqing; Qi, Tong; Wan, Houzhao

    2014-05-01

    Self-standing NiCo2S4 nanotube arrays have been in situ grown on Ni foam by the anion-exchange reaction and directly used as the electrode for supercapacitors. The NiCo2S4 nanotube in the arrays effectively reduces the inactive material and increases the electroactive surface area because of the ultrathin wall, which is quite competent to achieve high utilization efficiency at high electroactive materials mass loading. The NiCo2S4 nanotube arrays hybrid electrode exhibits an ultrahigh specific capacitance of 14.39 F cm-2 at 5 mA cm-2 with excellent rate performance (67.7% retention for current increases 30 times) and cycling stability (92% retention after 5000 cycles) at a high mass loading of 6 mg cm-2. High areal capacitance (4.68 F cm-2 at 10 mA cm-2), high energy density (31.5 Wh kg-1 at 156.6 W kg-1) and high power density (2348.5 W kg-1 at 16.6 Wh kg-1) can be achieved by assembling asymmetric supercapacitor with reduced graphene oxide at a total active material mass loading as high as 49.5 mg. This work demonstrates that NiCo2S4 nanotube arrays structure is a superior electroactive material for high-performance supercapacitors even at a mass loading of potential application-specific scale.

  3. 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. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. 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.

  5. A selective iodide ion sensor electrode based on functionalized ZnO nanotubes.

    Science.gov (United States)

    Ibupoto, Zafar Hussain; Khun, Kimleang; Willander, Magnus

    2013-02-04

    In this research work, ZnO nanotubes were fabricated on a gold coated glass substrate through chemical etching by the aqueous chemical growth method. For the first time a nanostructure-based iodide ion selective electrode was developed. The ZnO nanotubes were functionalized with miconazole ion exchanger and the electromotive force (EMF) was measured by the potentiometric method. The iodide ion sensor exhibited a linear response over a wide range of concentrations (1 × 10-6 to 1 × 10-1 M) and excellent sensitivity of -62 ± 1 mV/decade. The detection limit of the proposed sensor was found to be 5 × 10-7 M. The effects of pH, temperature, additive, plasticizer and stabilizer on the potential response of iodide ion selective electrode were also studied. The proposed iodide ion sensor demonstrated a fast response time of less than 5 s and high selectivity against common organic and the inorganic anions. All the obtained results revealed that the iodide ion sensor based on functionalized ZnO nanotubes may be used for the detection of iodide ion in environmental water samples, pharmaceutical products and other real samples.

  6. A Selective Iodide Ion Sensor Electrode Based on Functionalized ZnO Nanotubes

    Directory of Open Access Journals (Sweden)

    Magnus Willander

    2013-02-01

    Full Text Available In this research work, ZnO nanotubes were fabricated on a gold coated glass substrate through chemical etching by the aqueous chemical growth method. For the first time a nanostructure-based iodide ion selective electrode was developed. The ZnO nanotubes were functionalized with miconazole ion exchanger and the electromotive force (EMF was measured by the potentiometric method. The iodide ion sensor exhibited a linear response over a wide range of concentrations (1 × 10−6 to 1 × 10−1 M and excellent sensitivity of –62 ± 1 mV/decade. The detection limit of the proposed sensor was found to be 5 × 10−7 M. The effects of pH, temperature, additive, plasticizer and stabilizer on the potential response of iodide ion selective electrode were also studied. The proposed iodide ion sensor demonstrated a fast response time of less than 5 s and high selectivity against common organic and the inorganic anions. All the obtained results revealed that the iodide ion sensor based on functionalized ZnO nanotubes may be used for the detection of iodide ion in environmental water samples, pharmaceutical products and other real samples.

  7. Fabrication of combinatorial nm-planar electrode array for high throughput evaluation of organic semiconductors

    International Nuclear Information System (INIS)

    Haemori, M.; Edura, T.; Tsutsui, K.; Itaka, K.; Wada, Y.; Koinuma, H.

    2006-01-01

    We have fabricated a combinatorial nm-planar electrode array by using photolithography and chemical mechanical polishing processes for high throughput electrical evaluation of organic devices. Sub-nm precision was achieved with respect to the average level difference between each pair of electrodes and a dielectric layer. The insulating property between the electrodes is high enough to measure I-V characteristics of organic semiconductors. Bottom-contact field-effect-transistors (FETs) of pentacene were fabricated on this electrode array by use of molecular beam epitaxy. It was demonstrated that the array could be used as a pre-patterned device substrate for high throughput screening of the electrical properties of organic semiconductors

  8. Ultra-Low-Power Smart Electronic Nose System Based on Three-Dimensional Tin Oxide Nanotube Arrays.

    Science.gov (United States)

    Chen, Jiaqi; Chen, Zhuo; Boussaid, Farid; Zhang, Daquan; Pan, Xiaofang; Zhao, Huijuan; Bermak, Amine; Tsui, Chi-Ying; Wang, Xinran; Fan, Zhiyong

    2018-06-04

    In this work, we present a high-performance smart electronic nose (E-nose) system consisting of a multiplexed tin oxide (SnO 2 ) nanotube sensor array, read-out circuit, wireless data transmission unit, mobile phone receiver, and data processing application (App). Using the designed nanotube sensor device structure in conjunction with multiple electrode materials, high-sensitivity gas detection and discrimination have been achieved at room temperature, enabling a 1000 times reduction of the sensor's power consumption as compared to a conventional device using thin film SnO 2 . The experimental results demonstrate that the developed E-nose can identify indoor target gases using a simple vector-matching gas recognition algorithm. In addition, the fabricated E-nose has achieved state-of-the-art sensitivity for H 2 and benzene detection at room temperature with metal oxide sensors. Such a smart E-nose system can address the imperative needs for distributed environmental monitoring in smart homes, smart buildings, and smart cities.

  9. Effect of alignment on adsorption characteristics of self-oriented multi-walled carbon nanotube arrays

    International Nuclear Information System (INIS)

    Zilli, D; Bonelli, P R; Cukierman, A L

    2006-01-01

    The adsorption characteristics of self-oriented multi-walled carbon nanotube (MWCNT) arrays are examined from N 2 (-196 deg. C) adsorption measurements. The arrays were synthesized in a laboratory by in situ chemical vapour deposition of iron or cobalt phthalocyanines at 880 and 950 deg. C, under otherwise constant conditions, in an attempt to obtain different morphological structures. For both precursors, increasing the temperature leads to MWCNT arrays with lower Brunauer-Emmett-Teller (BET) surface area and total pore volume, though the effect is more pronounced for those arising from the iron-based compound. Despite this, precursor yields of individual nanotubes of larger diameter, higher BET area and total pore volume characterize the resulting arrays compared to those arising from cobalt phthalocyanine for the same temperatures. As evidenced by SEM and TEM images, the arrays synthesized from iron phthalocyanine at 880 deg. C show better vertical alignment and denser structures than those obtained from this compound at 950 deg. C, and also from cobalt phthalocyanine at both temperatures. Further ultrasonication of the arrays produced from the iron compound brings about a significant reduction in their adsorption capacity, attributable to the pronounced disarrangement of the resulting structures. The present results demonstrate that the alignment of MWCNT arrays plays a crucial role in their N 2 adsorption characteristics

  10. Surface-restrained growth of vertically aligned carbon nanotube arrays with excellent thermal transport performance.

    Science.gov (United States)

    Ping, Linquan; Hou, Peng-Xiang; Liu, Chang; Li, Jincheng; Zhao, Yang; Zhang, Feng; Ma, Chaoqun; Tai, Kaiping; Cong, Hongtao; Cheng, Hui-Ming

    2017-06-22

    A vertically aligned carbon nanotube (VACNT) array is a promising candidate for a high-performance thermal interface material in high-power microprocessors due to its excellent thermal transport property. However, its rough and entangled free tips always cause poor interfacial contact, which results in serious contact resistance dominating the total thermal resistance. Here, we employed a thin carbon cover to restrain the disorderly growth of the free tips of a VACNT array. As a result, all the free tips are seamlessly connected by this thin carbon cover and the top surface of the array is smoothed. This unique structure guarantees the participation of all the carbon nanotubes in the array in the heat transport. Consequently the VACNT array grown on a Cu substrate shows a record low thermal resistance of 0.8 mm 2 K W -1 including the two-sided contact resistances, which is 4 times lower than the best result previously reported. Remarkably, the VACNT array can be easily peeled away from the Cu substrate and act as a thermal pad with excellent flexibility, adhesive ability and heat transport capability. As a result the CNT array with a thin carbon cover shows great potential for use as a high-performance flexible thermal interface material.

  11. 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.

  12. Helically coiled carbon nanotube forests for use as electrodes in supercapacitors

    Science.gov (United States)

    Childress, Anthony; Ferri, Kevin; Podila, Ramakrishna; Rao, Apparao

    Supercapacitors are a class of devices which combine the high energy density of batteries with the power delivery of capacitors, and have benefitted greatly from the incorporation of carbon nanomaterials. In an effort to improve the specific capacitance of these devices, we have produced binder-free electrodes composed of helically coiled carbon nanotube forests grown on stainless steel current collectors with a performance superior to traditional carbon nanomaterials. By virtue of their helicity, the coiled nanotubes provide a greater surface area for energy storage than their straight counterparts, thus improving the specific capacitance. Furthermore, we used an Ar plasma treatment to increase the electronic density of states, and thereby the quantum capacitance, through the introduction of defects.

  13. Graphene-Vertically Aligned Carbon Nanotube Hybrid on PDMS as Stretchable Electrodes.

    Science.gov (United States)

    Ding, Junjun; Fu, Shichen; Zhang, Runzhi; Boon, Eric Peter; Lee, Woo; Fisher, Frank T; Yang, Eui-Hyeok

    2017-09-11

    Stretchable electrodes are a critical component for flexible electronics such as displays, energy devices, and wearable sensors. Carbon nanotubes (CNTs) and graphene have been considered for flexible electrode applications, due to their mechanical strength, high carrier mobility, and excellent thermal conductivity. Vertically aligned carbon nanotubes (VACNTs) provide the possibility to serve as interconnects to graphene sheets as stretchable electrodes that could maintain high electrical conductivity under large tensile strain. In this work, a graphene oxide (GO) -VACNT hybrid on a PDMS substrate was demonstrated. Here, 50 μm long VACNTs were grown on a Si/SiO2 wafer substrate via atmospheric pressure chemical vapor deposition (APCVD). VACNTs were directly transferred by delamination from the Si/SiO2 to a semi-cured PDMS substrate, ensuring strong adhesion between VACNTs and PDMS upon full curing of the PDMS. GO ink was then printed on the surface of the VACNT carpet and thermally reduced to reduced graphene oxide (rGO). The sheet resistance of the rGO-VACNT hybrid was measured under uniaxial tensile strains up to 300% applied to the substrate. Under applied strain, the rGO-VACNT hybrid maintained a sheet resistant of 386±55 Ω/sq. Cyclic stretching of the rGO-VACNT hybrid was performed with up to 50 cycles at 100% maximum tensile strain, showing no increase in sheet resistance. These results demonstrate promising performance of the rGO-VACNT hybrid for flexible electronics applications. © 2017 IOP Publishing Ltd.

  14. Advantages of electrodes with dendrimer-protected platinum nanoparticles and carbon nanotubes for electrochemical methanol oxidation.

    Science.gov (United States)

    Siriviriyanun, Ampornphan; Imae, Toyoko

    2013-04-14

    Electrochemical sensors consisting of electrodes loaded with carbon nanotubes and Pt nanoparticles (PtNPs) protected by dendrimers have been developed using a facile method to fabricate them on two types of disposable electrochemical printed chips with a screen-printed circular gold or a screen-printed circular glassy carbon working electrode. The electrochemical performance of these sensors in the oxidation of methanol was investigated by cyclic voltammetry. It was revealed that such sensors possess stable durability and high electrocatalytic activity: the potential and the current density of an anodic peak in the oxidation of methanol increased with increasing content of PtNPs on the electrodes, indicating the promotion of electrocatalytic activity in relation to the amount of catalyst. The low anodic potential suggests the easy electrochemical reaction, and the high catalyst tolerance supports the almost complete oxidation of methanol to carbon dioxide. The significant performance of these sensors in the detection of methanol oxidation comes from the high electrocatalytic ability of PtNPs, excellent energy transfer of carbon nanotubes and the remarkable ability of dendrimers to act as binders. Thus these systems are effective for a wide range of applications as chemical, biomedical, energy and environmental sensors and as units of direct methanol fuel cells.

  15. Graphene—vertically aligned carbon nanotube hybrid on PDMS as stretchable electrodes

    Science.gov (United States)

    Ding, Junjun; Fu, Shichen; Zhang, Runzhi; Boon, Eric; Lee, Woo; Fisher, Frank T.; Yang, Eui-Hyeok

    2017-11-01

    Stretchable electrodes are a critical component for flexible electronics such as displays, energy devices, and wearable sensors. Carbon nanotubes (CNTs) and graphene have been considered for flexible electrode applications, due to their mechanical strength, high carrier mobility, and excellent thermal conductivity. Vertically aligned carbon nanotubes (VACNTs) provide the possibility to serve as interconnects to graphene sheets as stretchable electrodes that could maintain high electrical conductivity under large tensile strain. In this work, a graphene oxide (GO)-VACNT hybrid on a PDMS substrate was demonstrated. Here, 50 μm long VACNTs were grown on a Si/SiO2 wafer substrate via atmospheric pressure chemical vapor deposition. VACNTs were directly transferred by delamination from the Si/SiO2 to a semi-cured PDMS substrate, ensuring strong adhesion between VACNTs and PDMS upon full curing of the PDMS. GO ink was then printed on the surface of the VACNT carpet and thermally reduced to reduced graphene oxide (rGO). The sheet resistance of the rGO-VACNT hybrid was measured under uniaxial tensile strains up to 300% applied to the substrate. Under applied strain, the rGO-VACNT hybrid maintained a sheet resistant of 386 ± 55 Ω/sq. Cyclic stretching of the rGO-VACNT hybrid was performed with up to 50 cycles at 100% maximum tensile strain, showing no increase in sheet resistance. These results demonstrate promising performance of the rGO-VACNT hybrid for flexible electronics applications.

  16. Dye-sensitized solar cells employing doubly or singly open-ended TiO2 nanotube arrays: structural geometry and charge transport.

    Science.gov (United States)

    Choi, Jongmin; Song, Seulki; Kang, Gyeongho; Park, Taiho

    2014-09-10

    We systematically investigated the charge transport properties of doubly or singly open-ended TiO2 nanotube arrays (DNT and SNT, respectively) for their utility as electrodes in dye-sensitized solar cells (DSCs). The SNT or DNT arrays were transferred in a bottom-up (B-up) or top-up (T-up) configuration onto a fluorine-doped tin oxide (FTO) substrate onto which had been deposited a 2 μm thick TiO2 nanoparticle (NP) interlayer. This process yielded four types of DSCs prepared with SNTs (B-up or T-up) or DNT (B-up or T-up). The photovoltaic performances of these DSCs were analyzed by measuring the dependence of the charge transport on the DSC geometry. High resolution scanning electron microscopy techniques were used to characterize the electrode cross sections, and electrochemical impedance spectroscopy was used to characterize the electrical connection at the interface between the NT array and the TiO2 NP interlayer. We examined the effects of decorating the DNT or SNT arrays with small NPs (sNP@DNT and sNP@SNT, respectively) in an effort to increase the extent of dye loading. The DNT arrays decorated with small NPs performed better than the decorated SNT arrays, most likely because the Ti(OH)4 precursor solution flowed freely into the array through the open ends of the NTs in the DNT case but not in the SNT case. The sNP@DNT-based DSC exhibited a better PCE (10%) compared to the sNP@SNT-based DSCs (6.8%) because the electrolyte solution flow was not restricted, direct electron transport though the NT arrays was possible, the electrical connection at the interface between the NT array and the TiO2 NP interlayer was good, and the array provided efficient light harvesting.

  17. Vertically aligned carbon nanotube field emitter arrays with Ohmic base contact to silicon by Fe-catalyzed chemical vapor deposition

    NARCIS (Netherlands)

    Morassutto, M.; Tiggelaar, Roald M.; Smithers, M.A.; Smithers, M.A.; Gardeniers, Johannes G.E.

    2016-01-01

    Abstract In this study, dense arrays of aligned carbon nanotubes are obtained by thermal catalytic chemical vapor deposition, using Fe catalyst dispersed on a thin Ta layer. Alignment of the carbon nanotubes depends on the original Fe layer thickness from which the catalyst dispersion is obtained by

  18. Single-layer graphene-TiO{sub 2} nanotubes array heterojunction for ultraviolet photodetector application

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Deng-Yue [School of Material Sciences and Engineering, Hefei University of Technology, Hefei, Anhui 230009 (China); Ge, Cai-Wang [School of Electronic Science and Applied Physics, Hefei University of Technology, Hefei, Anhui 230009 (China); Wang, Jiu-Zhen [School of Material Sciences and Engineering, Hefei University of Technology, Hefei, Anhui 230009 (China); Zhang, Teng-Fei [School of Electronic Science and Applied Physics, Hefei University of Technology, Hefei, Anhui 230009 (China); Wu, Yu-Cheng, E-mail: ycwu@hfut.edu.cn [School of Material Sciences and Engineering, Hefei University of Technology, Hefei, Anhui 230009 (China); Liang, Feng-Xia, E-mail: fxliang@hfut.edu.cn [School of Material Sciences and Engineering, Hefei University of Technology, Hefei, Anhui 230009 (China)

    2016-11-30

    Highlights: • Heterostructures comprised of a single-layer graphene and TiO{sub 2} nanotube arrays were constructed for ultraviolet detection. • The electrical properties of the fabricated heterostructures were dependent on the annealing atmospheres. • The effect of anodic TiO{sub 2} nanotube length on the performance of the photodetector were investigated. - Abstract: In this work, we reported on the fabrication of a single-layer graphene (SLG)-TiO{sub 2} nanotube arrays (NTs) heterostructures ultraviolet photodetector (UVPD) by transferring chemical vapor deposition derived MLG on the surface of anodic TiO{sub 2}NTs array. Through varying the annealing atmosphere and anodization time in the TiO{sub 2} synthesis procedure, the electronic and optoelectronic properties of the as-fabricated Schottky junction UVPD were studied. It was revealed that the anodic TiO{sub 2}NTs annealed in air showed a better rectifying behavior and was highly sensitive to UV light irradiation. Further investigation found that the device performance of the UVPD can be readily modulated by the anodization time, and the anodic TiO{sub 2}NTs with a medium tube length of 9.6 μm exhibits the highest device performance. These results demonstrated that the present SLG-TiO{sub 2}NTs array hetero-junction UVPD will be highly promising for fabricating high-performance optoelectronic device and system in the future.

  19. Electrochemistry of metoclopramide at multi-walled carbon nanotube modified electrode and its voltammetric detection.

    Science.gov (United States)

    Guo, Wei; Geng, Mingjiang; Zhou, Lingyun

    2012-01-01

    A simple, sensitive and inexpensive electrochemical method was developed for the determination of metoclopramide (MCP) with a multi-wall carbon nanotube (MWNT) modified glassy carbon electrode (GCE). MWNT was dispersed into polyacrylic acid (PAA); the aqueous suspension was then cast on GCE electrodes, forming MWNT-PAA films after evaporation of the solvent. The electrochemical behavior of MCP at the MWNT-modified electrode was investigated in detail. Compared with the bare GCE, the MWNT-modified electrode exhibits electrocatalytic activity to the oxidation of MCP because of the significant oxidation peak-current enhancement. Furthermore, various experimental parameters, such as the solution pH value, the amount of MWNT-PAA suspension and accumulation conditions were optimized for the determination of MCP. Based on the electrocatalytic effect of the MWNT-modified electrode, linear sweep voltammetry (LSV) was developed for the determination of MCP with the linear response in the range from 1.0 × 10(-7) to 1.0 × 10(-5) mol L(-1) and a detection limit of 5.0 × 10(-8) mol L(-1). The method has been successfully applied to the determination of MCP in commercial MCP tablets.

  20. Room temperature alcohol sensing by oxygen vacancy controlled TiO2 nanotube array

    International Nuclear Information System (INIS)

    Hazra, A.; Dutta, K.; Bhowmik, B.; Bhattacharyya, P.; Chattopadhyay, P. P.

    2014-01-01

    Oxygen vacancy (OV) controlled TiO 2 nanotubes, having diameters of 50–70 nm and lengths of 200–250 nm, were synthesized by electrochemical anodization in the mixed electrolyte comprising NH 4 F and ethylene glycol with selective H 2 O content. The structural evolution of TiO 2 nanoforms has been studied by field emission scanning electron microscopy. Variation in the formation of OVs with the variation of the structure of TiO 2 nanoforms has been evaluated by photoluminescence and X-ray photoelectron spectroscopy. The sensor characteristics were correlated to the variation of the amount of induced OVs in the nanotubes. The efficient room temperature sensing achieved by the control of OVs of TiO 2 nanotube array has paved the way for developing fast responding alcohol sensor with corresponding response magnitude of 60.2%, 45.3%, and 36.5% towards methanol, ethanol, and 2-propanol, respectively.

  1. The new mid-scala electrode array: a radiologic and histologic study in human temporal bones.

    Science.gov (United States)

    Hassepass, Frederike; Bulla, Stefan; Maier, Wolfgang; Laszig, Roland; Arndt, Susan; Beck, Rainer; Traser, Lousia; Aschendorff, Antje

    2014-09-01

    To analyze the quality of insertion of the newly developed midscala (MS) electrode, which targets a midscalar electrode position to reduce the risk of trauma to the lateral wall and the modiolus. Modern cochlear implant surgery aims for a safe intracochlear placement of electrode arrays with an ongoing debate regarding cochleostomy or round window (RW) insertion and the use of lateral wall or perimodiolar electrode placement. Intracochlear trauma after insertion of different electrodes depends on insertion mode and electrode design and may result in trauma to the delicate structures of the cochlear. We performed a temporal bone (TB) trial with insertion of the MS electrode in n = 20 TB's after a mastoidectomy and posterior tympanotomy. Insertion was performed either via the RW or a cochleostomy. Electrode positioning, length of insertion, and angle of insertion were analyzed with rotational tomography (RT). TBs were histologically analyzed. Results of RT and histology were compared. Scala tympani (ST) insertion could be accomplished reliably by both RW and via a cochleostomy approach. In 20 TBs, 1 scala vestibuli insertion, 1 incomplete (ST), and 1 elevation of basilar membrane were depicted. No trauma was found in 94.7% of all ST insertions. RT allowed determination of the intracochlear electrode position, which was specified by histologic sectioning. The new MS electrode seems to fulfill reliable atraumatic intracochlear placement via RW and cochleostomy approaches. RT is available for evaluation of intracochlear electrode position, serving as a potential quality control instrument in human implantation.

  2. Electric Double-Layer Capacitor Fabricated with Addition of Carbon Nanotube to Polarizable Electrode

    Directory of Open Access Journals (Sweden)

    Yoshiyuki Show

    2012-01-01

    Full Text Available Electrical double-layer capacitor (EDLC was fabricated with addition of carbon nanotube (CNT to polarization electrodes as a conducting material. The CNT addition reduced the series resistance of the EDLC by one-twentieth, while the capacitance was not increased by the CNT addition. The low series resistance leaded to the high electrical energy stored in the EDLC. In this paper, the dependence of the series resistance, the specific capacitance, the energy, and the energy efficiencies on the CNT addition is discussed.

  3. High performance dye-sensitized solar cell based on hydrothermally deposited multiwall carbon nanotube counter electrode

    Science.gov (United States)

    Siriroj, Sumeth; Pimanpang, Samuk; Towannang, Madsakorn; Maiaugree, Wasan; Phumying, Santi; Jarernboon, Wirat; Amornkitbamrung, Vittaya

    2012-06-01

    Conductive glass was coated with multiwall carbon nanotubes (MWCNTs) by a hydrothermal method. MWCNTs films were subsequently used as dye-sensitized solar cell (DSSC) counter electrodes. The performance of hydrothermal MWCNT DSSC was ˜2.37%. After film annealing in an Ar atmosphere, annealed-hydrothermal MWCNT (AHT-CNT) DSSC efficiency was significantly increased to ˜7.66%, in comparison to ˜8.01% for sputtered-Pt DSSC. Improvement of AHT-CNT DSSC performance is attributed to a decrease in charge-transfer resistance from 1500 Ω to 30 Ω as observed by electrochemical impedance spectroscopy.

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

    International Nuclear Information System (INIS)

    Chen, K.-C.; Chen, C.-F.; Chiang, J.-S.; Hwang, C.-L.; Chang, Y.-Y.; Lee, C.-C.

    2006-01-01

    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 4 /H 2 gas mixture below 550 deg. C. In the field emission measurement, the turn-on field was 3.2 V/μm and uniform electron emission image was also observed

  5. Rapid prototyping of flexible intrafascicular electrode arrays by picosecond laser structuring.

    Science.gov (United States)

    Mueller, Matthias; de la Oliva, Natalia; Del Valle, Jaume; Delgado-Martínez, Ignacio; Navarro, Xavier; Stieglitz, Thomas

    2017-12-01

    Interfacing the peripheral nervous system can be performed with a large variety of electrode arrays. However, stimulating and recording a nerve while having a reasonable amount of channels limits the number of available systems. Translational research towards human clinical trial requires device safety and biocompatibility but would benefit from design flexibility in the development process to individualize probes. We selected established medical grade implant materials like precious metals and Parylene C to develop a rapid prototyping process for novel intrafascicular electrode arrays using a picosecond laser structuring. A design for a rodent animal model was developed in conjunction with an intrafascicular implantation strategy. Electrode characterization and optimization was performed first in saline solution in vitro before performance and biocompatibility were validated in sciatic nerves of rats in chronic implantation. The novel fabrication process proved to be suitable for prototyping and building intrafascicular electrode arrays. Electrochemical properties of the electrode sites were enhanced and tested for long-term stability. Chronic implantation in the sciatic nerve of rats showed good biocompatibility, selectivity and stable stimulation thresholds. Established medical grade materials can be used for intrafascicular nerve electrode arrays when laser structuring defines structure size in the micro-scale. Design flexibility reduces re-design cycle time and material certificates are beneficial support for safety studies on the way to clinical trials.

  6. Phosphorization boosts the capacitance of mixed metal nanosheet arrays for high performance supercapacitor electrodes.

    Science.gov (United States)

    Lan, Yingying; Zhao, Hongyang; Zong, Yan; Li, Xinghua; Sun, Yong; Feng, Juan; Wang, Yan; Zheng, Xinliang; Du, Yaping

    2018-05-01

    Binary transition metal phosphides hold immense potential as innovative electrode materials for constructing high-performance energy storage devices. Herein, porous binary nickel-cobalt phosphide (NiCoP) nanosheet arrays anchored on nickel foam (NF) were rationally designed as self-supported binder-free electrodes with high supercapacitance performance. Taking the combined advantages of compositional features and array architectures, the nickel foam supported NiCoP nanosheet array (NiCoP@NF) electrode possesses superior electrochemical performance in comparison with Ni-Co LDH@NF and NiCoO2@NF electrodes. The NiCoP@NF electrode shows an ultrahigh specific capacitance of 2143 F g-1 at 1 A g-1 and retained 1615 F g-1 even at 20 A g-1, showing excellent rate performance. Furthermore, a binder-free all-solid-state asymmetric supercapacitor device is designed, which exhibits a high energy density of 27 W h kg-1 at a power density of 647 W kg-1. The hierarchical binary nickel-cobalt phosphide nanosheet arrays hold great promise as advanced electrode materials for supercapacitors with high electrochemical performance.

  7. Simulating pad-electrodes with high-definition arrays in transcranial electric stimulation

    Science.gov (United States)

    Kempe, René; Huang, Yu; Parra, Lucas C.

    2014-04-01

    Objective. Research studies on transcranial electric stimulation, including direct current, often use a computational model to provide guidance on the placing of sponge-electrode pads. However, the expertise and computational resources needed for finite element modeling (FEM) make modeling impractical in a clinical setting. Our objective is to make the exploration of different electrode configurations accessible to practitioners. We provide an efficient tool to estimate current distributions for arbitrary pad configurations while obviating the need for complex simulation software. Approach. To efficiently estimate current distributions for arbitrary pad configurations we propose to simulate pads with an array of high-definition (HD) electrodes and use an efficient linear superposition to then quickly evaluate different electrode configurations. Main results. Numerical results on ten different pad configurations on a normal individual show that electric field intensity simulated with the sampled array deviates from the solutions with pads by only 5% and the locations of peak magnitude fields have a 94% overlap when using a dense array of 336 electrodes. Significance. Computationally intensive FEM modeling of the HD array needs to be performed only once, perhaps on a set of standard heads that can be made available to multiple users. The present results confirm that by using these models one can now quickly and accurately explore and select pad-electrode montages to match a particular clinical need.

  8. Rapid prototyping of flexible intrafascicular electrode arrays by picosecond laser structuring

    Science.gov (United States)

    Mueller, Matthias; de la Oliva, Natalia; del Valle, Jaume; Delgado-Martínez, Ignacio; Navarro, Xavier; Stieglitz, Thomas

    2017-12-01

    Objective. Interfacing the peripheral nervous system can be performed with a large variety of electrode arrays. However, stimulating and recording a nerve while having a reasonable amount of channels limits the number of available systems. Translational research towards human clinical trial requires device safety and biocompatibility but would benefit from design flexibility in the development process to individualize probes. Approach. We selected established medical grade implant materials like precious metals and Parylene C to develop a rapid prototyping process for novel intrafascicular electrode arrays using a picosecond laser structuring. A design for a rodent animal model was developed in conjunction with an intrafascicular implantation strategy. Electrode characterization and optimization was performed first in saline solution in vitro before performance and biocompatibility were validated in sciatic nerves of rats in chronic implantation. Main results. The novel fabrication process proved to be suitable for prototyping and building intrafascicular electrode arrays. Electrochemical properties of the electrode sites were enhanced and tested for long-term stability. Chronic implantation in the sciatic nerve of rats showed good biocompatibility, selectivity and stable stimulation thresholds. Significance. Established medical grade materials can be used for intrafascicular nerve electrode arrays when laser structuring defines structure size in the micro-scale. Design flexibility reduces re-design cycle time and material certificates are beneficial support for safety studies on the way to clinical trials.

  9. Fuel Cell Electrodes Based on Carbon Nanotube/Metallic Nanoparticles Hybrids Formed on Porous Stainless Steel Pellets

    Directory of Open Access Journals (Sweden)

    S. M. Khantimerov

    2013-01-01

    Full Text Available The preparation of carbon nanotube/metallic particle hybrids using pressed porous stainless steel pellets as a substrate is described. The catalytic growth of carbon nanotubes was carried out by CVD on a nickel catalyst obtained by impregnation of pellets with a highly dispersive colloidal solution of nickel acetate tetrahydrate in ethanol. Granular polyethylene was used as the carbon source. Metallic particles were deposited by thermal evaporation of Pt and Ag using pellets with grown carbon nanotubes as a base. The use of such composites as fuel cell electrodes is discussed.

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

    International Nuclear Information System (INIS)

    Rajalakshmi, K.; Abraham John, S.

    2015-01-01

    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

  11. Electrospun carbon nanofibers surface-grafted with vapor-grown carbon nanotubes as hierarchical electrodes for supercapacitors

    Science.gov (United States)

    Zhou, Zhengping; Wu, Xiang-Fa; Fong, Hao

    2012-01-01

    This letter reports the fabrication and electrochemical properties of electrospun carbon nanofibers surface-grafted with vapor-grown carbon nanotubes (CNTs) as hierarchical electrodes for supercapacitors. The specific capacitance of the fabricated electrodes was measured up to 185 F/g at the low discharge current density of 625 mA/g; a decrease of 38% was detected at the high discharge current density of 2.5 A/g. The morphology and microstructure of the electrodes were examined by electron microscopy, and the unique connectivity of the hybrid nanomaterials was responsible for the high specific capacitance and low intrinsic contact electric resistance of the hierarchical electrodes.

  12. Perspectives on State-of-the-Art Carbon Nanotube/Polyaniline and Graphene/Polyaniline Composites for Hybrid Supercapacitor Electrodes.

    Science.gov (United States)

    Srikanth, Vadali V S S; Ramana, Gedela Venkata; Kumar, Puttapati Sampath

    2016-03-01

    Supercapacitors are attractive alternative energy storage sources. They offer high energy/power density with other characteristics like fast discharge/charge time, long operation stability, safety etc. In a supercapacitor, working electrode material is the principal constituent. At present there are numerous electrode materials (with properties) suitable for their use in hybrid type supercapacitors. Carbon/polyaniline (PANi) composites are one class of such electrode materials. Here, perspectives on state-of-the-art carbon/PANi composites namely carbon nanotube/polyaniline and graphene/polyaniline composites expedient as hybrid type supercapacitor electrode materials will be presented.

  13. Impact of cell-voltage on energy and power performance of supercapacitors with single-walled carbon nanotube electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Izadi-Najafabadi, Ali; Yamada, Takeo; Futaba, Don N.; Iijima, Sumio [Nanotube Research Center, National Institute of Advanced Industrial Science and Technology, Tsukuba (Japan); Hatori, Hiroaki [Project Headquarters, National Institute of Advanced Industrial Science and Technology, Tsukuba (Japan); Hata, Kenji [Japan Science and Technology Agency JST, Kawaguchi (Japan)

    2010-12-15

    We report the energy and power voltage-dependencies of supercapacitors using single-walled carbon nanotube electrodes. The energy density was dependent on the cell-voltage cubed (up to 4 V: E = 1.43 x V{sup 3}). The cubic relationship was attributed to the linear increase of the capacitance as a function of voltage, enabled by electrochemical doping. Furthermore, while up to 3.5 V, the maximum power rating of the nanotube electrodes increased as a function of the cell-voltage squared, beyond 3.5 V, a decline in power was observed as a result of depletion of the electrolyte's ions. (author)

  14. ZnO nanorod–templated well-aligned ZrO2 nanotube arrays for fibroblast adhesion and proliferation

    International Nuclear Information System (INIS)

    Lu, Zhisong; Hu, Weihua; Ming Li, Chang; Zhu, Zhihong; Liu, Jinping

    2014-01-01

    Cellular responses to porous tubular structures have recently been investigated in highly ordered ZrO 2 nanotube arrays fabricated with anodization. However, the potential applications of the nanotube arrays are hindered by instrument requirements and substrate limitations, as well as by the complicated processes needed for synthesis. In this work, ZrO 2 nanotube arrays were synthesized by in situ hydrolysis of zirconium propoxide with a zinc oxide nanorod array–based template. Fibroblast cells were able to grow on the nanotube array surface with produced elongated filopodia. Studies of the capability of cell growth and the expression of adhesion- and proliferation-related genes reveal that ZrO 2 nanotube arrays may provide a better environment for cell adhesion and growth than a flat titanium surface. These findings not only provide fundamental insight into cell response to nanostructures but also provide an opportunity to use a unique approach to fabricate ZrO 2 nanotube array structures for potential implant applications. (papers)

  15. Fast fabrication of long TiO2 nanotube array with high photoelectrochemical property on flexible stainless steel.

    Science.gov (United States)

    Tao, Jie; Wu, Tao; Gao, Peng

    2012-03-01

    Oriented highly ordered long TiO2 nanotube array films with nanopore structure and high photoelectrochemical property were fabricated on flexible stainless steel substrate (50 microm) by anodization treatment of titanium thin films in a short time. The samples were characterized by means of field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and photoelectrochemical methods, respectively. The results showed that Ti films deposited at the condition of 0.7 Pa Ar pressure and 96 W sputtering power at room temperature was uniform and dense with good homogeneity and high crystallinity. The voltage and the anodization time both played significant roles in the formation of TiO2 nanopore-nanotube array film. The optimal voltage was 60 V and the anodization time is less than 30 min by anodizing Ti films in ethylene glycerol containing 0.5% (w) NH4F and 3% (w) H2O. The growth rate of TiO2 nanotube array was as high as 340 nm/min. Moreover, the photocurrent-potential curves, photocurrent response curves and electrochemical impedance spectra results indicated that the TiO2 nanotube array film with the nanoporous structure exhibited a better photo-response ability and photoelectrochemical performance than the ordinary TiO2 nanotube array film. The reason is that the nanoporous structure on the surface of the nanotube array can separate the photo electron-hole pairs more efficiently and completely than the tubular structure.

  16. Carbon Nanotube Modified Screen Printed Electrodes: Pyranose Oxidase Immobilization Platform for Amperometric Enzyme Sensors

    Directory of Open Access Journals (Sweden)

    Dilek ODACI DEMIRKOL

    2017-03-01

    Full Text Available Here, a novel enzymatic biosensor was developed using multiwalled carbon nanotube including screen printed electrodes (MWCNT-SPE. Pyranose oxidase (PyOx was immobilized on the electrode surface by way of gelatin membrane and then cross-linked using glutaraldehyde. Glucose was detected at -0.7 V (vs. Ag/AgCl by watching consumed oxygen in enzymatic reaction after addition substrate. After optimization of pH and enzyme loading, the linearity was found in the range of 0.1–1.0 mM of glucose. After that, the effect of MCNT on the current was tested. Also the enzymatic biosensor including glucose oxidase instead of pyranose oxidase was prepared and the biosensor response followed for glucose. Furthermore, this system was tested for glucose analysis in soft drinks.

  17. Transparent and flexible electrodes and supercapacitors using polyaniline/single-walled carbon nanotube composite thin films

    Science.gov (United States)

    Ge, Jun; Cheng, Guanghui; Chen, Liwei

    2011-08-01

    Large-scale transparent and flexible electronic devices have been pursued for potential applications such as those in touch sensors and display technologies. These applications require that the power source of these devices must also comply with transparent and flexible features. Here we present transparent and flexible supercapacitors assembled from polyaniline (PANI)/single-walled carbon nanotube (SWNT) composite thin film electrodes. The ultrathin, optically homogeneous and transparent, electrically conducting films of the PANI/SWNT composite show a large specific capacitance due to combined double-layer capacitance and pseudo-capacitance mechanisms. A supercapacitor assembled using electrodes with a SWNT density of 10.0 µg cm-2 and 59 wt% PANI gives a specific capacitance of 55.0 F g-1 at a current density of 2.6 A g-1, showing its possibility for transparent and flexible energy storage.

  18. Roll-to-roll production of spray coated N-doped carbon nanotube electrodes for supercapacitors

    Science.gov (United States)

    Karakaya, Mehmet; Zhu, Jingyi; Raghavendra, Achyut J.; Podila, Ramakrishna; Parler, Samuel G.; Kaplan, James P.; Rao, Apparao M.

    2014-12-01

    Although carbon nanomaterials are being increasingly used in energy storage, there has been a lack of inexpensive, continuous, and scalable synthesis methods. Here, we present a scalable roll-to-roll (R2R) spray coating process for synthesizing randomly oriented multi-walled carbon nanotubes electrodes on Al foils. The coin and jellyroll type supercapacitors comprised such electrodes yield high power densities (˜700 mW/cm3) and energy densities (1 mW h/cm3) on par with Li-ion thin film batteries. These devices exhibit excellent cycle stability with no loss in performance over more than a thousand cycles. Our cost analysis shows that the R2R spray coating process can produce supercapacitors with 10 times the energy density of conventional activated carbon devices at ˜17% lower cost.

  19. Electrochemical parameters of ethamsylate at multi-walled carbon nanotube modified glassy carbon electrodes.

    Science.gov (United States)

    Wang, Sheng-Fu; Xu, Qiao

    2007-05-01

    In this paper, some electrochemical parameters of ethamsylate at a multi-walled carbon nanotube modified glassy carbon electrode, such as the charge number, exchange current density, standard heterogeneous rate constant and diffusion coefficient, were measured by cyclic voltammetry, chronoamperometry and chronocoulometry. The modified electrode exhibits good promotion of the electrochemical reaction of ethamsylate and increases the standard heterogeneous rate constant of ethamsylate greatly. The differential pulse voltammetry responses of ethamsylate were linearly dependent on its concentrations in a range from 2.0 x 10(-6) to 6.0 x 10(-5) mol L(-1), with a detection limit of 4.0 x 10(-7) mol L(-1).

  20. Voltammetric determination of carbidopa and folic acid using a modified carbon nanotubes paste electrode

    Directory of Open Access Journals (Sweden)

    Keshtkar Nasrin

    2015-01-01

    Full Text Available A novel electrochemical sensor for the selective and sensitive detection of carbidopa in presence of large excess of folic acid at physiological pH was developed by the bulk modification of carbon paste electrode (CPE with carbon nanotubes (CNTs and vinylferrocene. Large peak separation, good sensitivity and stability allow this modified electrode to analyze carbidopa individually and simultaneously along with folic acid. Applying square wave voltammetry (SWV, a linear dynamic range of 1.0×10-6- 7.0×10-4 M with detection limit of 2.0×10-7 M was obtained for carbidopa. Finally, the proposed method was applied to the determination of carbidopa and folic acid in urine sample.

  1. 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.

  2. 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.

  3. Using Ag-embedded TiO{sub 2} nanotubes array as recyclable SERS substrate

    Energy Technology Data Exchange (ETDEWEB)

    Ling, Yunhan, E-mail: yhling@mail.tsinghua.edu.cn [Lab of Advanced Materials, School of Materials Science & Engineering, Tsinghua University, Beijing 100084 (China); Zhuo, Yuqing; Huang, Liang [Lab of Advanced Materials, School of Materials Science & Engineering, Tsinghua University, Beijing 100084 (China); Mao, Duolu [School of Physical and Electronic Information Engineering, Qinghai Nationalities University, Xining, Qinghai 810007 (China)

    2016-12-01

    Highlights: • Ag embedded nanoparticles inside nanotube have better SERS enhancement than surface cap. • Ag NPs reconstruction via self-migration with UV and humidity control. • Self-cleaning effects both on organic molecule photo-oxidation as well as Ag ions photo-reduction. - Abstract: A simple strategy for synthesizing Ag-loaded TiO{sub 2} nanotube film for use as multifunctional photocatalyst and recyclable surface-enhanced Raman scattering (SERS) substrate is introduced. Highly aligned TiO{sub 2} nanotube arrays (TNTA) prepared via electrochemical anodization were used as a 3D rough host for silver nanoparticles. Ag deposits were sputtered in a vacuum, and it was found that their morphologies were mainly influenced by the diameters of nanotubes and the UV irradiation induced aging process, especially the self-migration of silver along the tubular wall. SERS and the self-cleaning effect were observed using Rhodamine 6G (R6G) as the probe molecule. The results showed that narrow nanotube and silver nanoparticles embedment contributed significantly to both the phenomenal SERS and recyclability.

  4. Synthesis of Fe2O3/TiO2 nanorod-nanotube arrays by filling TiO2 nanotubes with Fe

    International Nuclear Information System (INIS)

    Mohapatra, Susanta K; Banerjee, Subarna; Misra, Mano

    2008-01-01

    Synthesis of hematite (α-Fe 2 O 3 ) nanostructures on a titania (TiO 2 ) nanotubular template is carried out using a pulsed electrodeposition technique. The TiO 2 nanotubes are prepared by the sonoelectrochemical anodization method and are filled with iron (Fe) by pulsed electrodeposition. The Fe/TiO 2 composite is then annealed in an O 2 atmosphere to convert it to Fe 2 O 3 /TiO 2 nanorod-nanotube arrays. The length of the Fe 2 O 3 inside the TiO 2 nanotubes can be tuned from 50 to 550 nm by changing the deposition time. The composite material is characterized by scanning electron microscopy, transmission electron microscopy and diffuse reflectance ultraviolet-visible studies to confirm the formation of one-dimensional Fe 2 O 3 /TiO 2 nanorod-nanotube arrays. The present approach can be used for designing variable one-dimensional metal oxide heterostructures

  5. Tunable TiO2 Nanotube Arrays for Flexible Bio-Sensitized Solar Cells

    Science.gov (United States)

    2012-08-01

    microid extender followed by a colloidal silica /wetted imperial cloth. The foil was then cut into 1- × 2-cm samples. Then, the substrates were...17. Lei, B.; Liao, J.; Wang, R. J.; Su, C.; Kuang, D. Ordered Crystalline Ti02 Nanotube Arrays on Transparent FTO Glass for Efficient Dye...combined with a transparent , Indium Tin Dioxide coated PET film are attractive candidates for efficient, flexible DSSC’s. Flexible solar cells offer

  6. Self-Assembled TiO2 Nanotube Arrays with U-Shaped Profile by Controlling Anodization Temperature

    Directory of Open Access Journals (Sweden)

    Jingfei Chen

    2010-01-01

    Full Text Available TiO2 nanotube arrays with uniform diameter from top to bottom were fabricated. The synthesizing approach is based on the investigation of the influence of electrolyte temperature on the tube diameter. We found that the inner diameter of the tubes increased with the electrolyte temperature. Accordingly, we improved the tube profile from the general V shape to U shape by raising the electrolyte temperature gradually. This is a simple and fast approach to fabricate uniform TiO2 nanotubes in diameter. The improved TiO2 nanotube arrays may show better properties and have broad potential applications.

  7. A visible-light-driven composite photocatalyst of TiO2 nanotube arrays and graphene quantum dots

    Directory of Open Access Journals (Sweden)

    Donald K. L. Chan

    2014-05-01

    Full Text Available TiO2 nanotube arrays are well-known efficient UV-driven photocatalysts. The incorporation of graphene quantum dots could extend the photo-response of the nanotubes to the visible-light range. Graphene quantum dot-sensitized TiO2 nanotube arrays were synthesized by covalently coupling these two materials. The product was characterized by Fourier-transform infrared spectrometry (FTIR, scanning electron microscopy (SEM, transmission electron microscopy (TEM, X-ray diffraction (XRD, thermogravimetric analysis (TGA and UV–vis absorption spectroscopy. The product exhibited high photocatalytic performance in the photodegradation of methylene blue and enhanced photocurrent under visible light irradiation.

  8. Servo scanning 3D micro EDM for array micro cavities using on-machine fabricated tool electrodes

    Science.gov (United States)

    Tong, Hao; Li, Yong; Zhang, Long

    2018-02-01

    Array micro cavities are useful in many fields including in micro molds, optical devices, biochips and so on. Array servo scanning micro electro discharge machining (EDM), using array micro electrodes with simple cross-sectional shape, has the advantage of machining complex 3D micro cavities in batches. In this paper, the machining errors caused by offline-fabricated array micro electrodes are analyzed in particular, and then a machining process of array servo scanning micro EDM is proposed by using on-machine fabricated array micro electrodes. The array micro electrodes are fabricated on-machine by combined procedures including wire electro discharge grinding, array reverse copying and electrode end trimming. Nine-array tool electrodes with Φ80 µm diameter and 600 µm length are obtained. Furthermore, the proposed process is verified by several machining experiments for achieving nine-array hexagonal micro cavities with top side length of 300 µm, bottom side length of 150 µm, and depth of 112 µm or 120 µm. In the experiments, a chip hump accumulates on the electrode tips like the built-up edge in mechanical machining under the conditions of brass workpieces, copper electrodes and the dielectric of deionized water. The accumulated hump can be avoided by replacing the water dielectric by an oil dielectric.

  9. Fully-flexible supercapacitors using spray-deposited carbon-nanotube films as electrodes

    Science.gov (United States)

    Lee, Churl Seung; Bae, Joonho

    2013-12-01

    Fully-flexible carbon-nanotube-based supercapacitors were successfully fabricated using a spray method. For electrodes, multiwalled carbon-nanotube films sprayed on polyethylene terephthalate (PET) substrates were employed. Thin Al films on PET were used as current collectors. The electrolyte was 1 M KNO3. Cyclic voltammetry and galvanostatic charge-discharge measurements on the flexible supercapacitors revealed that the area-specific capacitance was 0.11 mF/cm2. Electrochemical impedance spectroscopy of the supercapacitors resulted in a low internal resistance (3.7 Ω). The energy density and the power density of the flexible supercapacitor were measured to be 3.06 × 10-8 Wh/cm2 and 2.65 × 10-7 W/cm2, respectively. The Bode | z| and phase-angle plots showed that the supercapacitors functioned close to ideal capacitors at the frequencies near 2 kHz. These results indicate that the spray deposition method of carbon nanotubes could be promising for fabricating flexible energy devices or electronics.

  10. Terahertz generation via laser coupling to anharmonic carbon nanotube array

    Science.gov (United States)

    Sharma, Soni; Vijay, A.

    2018-02-01

    A scheme of terahertz radiation generation employing a matrix of anharmonic carbon nanotubes (CNTs) embedded in silica is proposed. The matrix is irradiated by two collinear laser beams that induce large excursions on CNT electrons and exert a nonlinear force at the beat frequency ω = ω1-ω2. The force derives a nonlinear current producing THz radiation. The THz field is resonantly enhanced at the plasmon resource, ω = ω p ( 1 + β ) / √{ 2 } , where ωp is the plasma frequency and β is a characteristic parameter. Collisions are a limiting factor, suppressing the plasmon resonance. For typical values of plasma parameters, we obtain power conversion efficiency of the order of 10-6.

  11. Anisotropically functionalized carbon nanotube array based hygroscopic scaffolds.

    Science.gov (United States)

    Ozden, Sehmus; Ge, Liehui; Narayanan, Tharangattu N; Hart, Amelia H C; Yang, Hyunseung; Sridhar, Srividya; Vajtai, Robert; Ajayan, Pulickel M

    2014-07-09

    Creating ordered microstructures with hydrophobic and hydrophilic moieties that enable the collection and storage of small water droplets from the atmosphere, mimicking structures that exist in insects, such as the Stenocara beetle, which live in environments with limited amounts of water. Inspired by this approach, vertically aligned multiwalled carbon nanotube forests (NTFs) are asymmetrically end-functionalized to create hygroscopic scaffolds for water harvesting and storage from atmospheric air. One side of the NTF is made hydrophilic, which captures water from the atmosphere, and the other side is made superhydrophobic, which prevents water from escaping and the forest from collapsing. To understand how water penetrates into the NTF, the fundamentals of water/NTF surface interaction are discussed.

  12. The different electron transport of two nanotubes incorporated in working electrode of dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaobo, E-mail: zhangxiaobo@chnu.edu.cn [School of Physics, Huaibei Normal University, Huaibei 235000, Anhui (China); Eco-Materials and Renewable Energy Research Centre (ERERC), Nanjing University, Nanjing 210093 (China); Tian, Hanmin; Wang, Xiangyan; Xue, Guogang; Tian, Zhipeng; Zhang, Jiyuan; Yuan, Shikui [Eco-Materials and Renewable Energy Research Centre (ERERC), Nanjing University, Nanjing 210093 (China); Yu, Tao; Zou, Zhigang [Eco-Materials and Renewable Energy Research Centre (ERERC), Nanjing University, Nanjing 210093 (China); National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China)

    2013-11-25

    Highlights: •Two TiO{sub 2} nanotubes are separately incorporated in working electrode of DSSCs. •The 6-μm-tubes incorporation improves electron transport in the cell. •The 1-μm-tubes incorporation impedes electron transport in the cell. •Both 1-D electron diffusion and nanotube percolation promote electron transport. •Electron residing at the end of 1-μm-tubes maybe impedes electron transport. -- Abstract: Two different-length (6 μm and 1 μm) TiO{sub 2} nanotubes were prepared and incorporated in working electrode of dye-sensitized solar cells (DSSCs). The analyses of the electrochemical impedance spectra of cells demonstrate that, the electron transport resistance R{sub w} decreases and increases separately to 0.3 Ω in 6-μm-tubes-cell and to 15.1 Ω in 1-μm-tubes-cell comparing with that 1.4 Ω in P25-cell, reflecting the improved electron transport in 6-μm-tubes-cell and impeded electron transport in 1-μm-tubes-cell. The reason is ascribed to the different electron transport in working electrode due to the incorporation of nanotubes. For the 6-μm-tubes incorporation, both 1-D electron diffusion along nanotubes and nanotube percolation improve electron transport in working electrode, but they cannot improve electron transport for the 1-μm-tubes incorporation. On the contrary, the 1-μm-tubes incorporation may impede electron transport because of electron residing occurring seriously at the end of 1-μm-tubes. The results of this work will help to understand the specific nature of electron transport in TiO{sub 2} nanotubes in DSSCs.

  13. Enhanced Photocatalytic Properties of Ag-Loaded N-Doped Tio2 Nanotube Arrays

    Directory of Open Access Journals (Sweden)

    Gao Dawei

    2018-03-01

    Full Text Available Highly ordered TiO2 nanotube (TiO2 NT arrays were prepared by anodic oxidizing method on the surface of the Ti substrate. Nitrogen-doped TiO2 nanotube (N-TiO2 NT arrays were carried out by ammonia solution immersion, and Ag nanoparticles loaded N-doped TiO2 nanotube (Ag/N-TiO2 NT arrays were obtained by successive ionic layer adsorption and reaction (SILAR technique. The samples were characterized by the X-ray diffraction (XRD, X-ray photoelectron spectroscopy (XPS, field emission scanning electron microscopy (FESEM, high-resolution transmission electron microscopy (HRTEM, photoluminescence (PL emission spectra, ultraviolet–visible (UV–vis diffuse reflectance spectroscopy (DRS. The result indicated that the diameter and wall thickness of the TiO2 NT are 100–120 and 20–30 nm, respectively. Moreover, the morphology and structure of the highly ordered TiO2 NTs were not affected by N-doping. Furthermore, Ag nanoparticles were evenly deposited on the surface of TiO2 NTs in the form of elemental silver. Finally, the photocatalytic activity of Ag/N-TiO2 NTs was evaluated by degradation of methyl orange (MO under visible-light irradiation. The Ag/N-TiO2 NTs exhibited enhanced photocatalytic properties, which could reach 95% after 90-min irradiation.

  14. Indium tin oxide-rod/single walled carbon nanotube based transparent electrodes for ultraviolet light-emitting diodes

    International Nuclear Information System (INIS)

    Yun, Min Ju; Kim, Hee-Dong; Kim, Kyeong Heon; Sung, Hwan Jun; Park, Sang Young; An, Ho-Myoung; Kim, Tae Geun

    2013-01-01

    In this paper, we report a transparent conductive oxide electrode scheme working for ultraviolet light-emitting diodes based on indium tin oxide (ITO)-rod and a single walled carbon nanotube (SWCNT) layer. We prepared four samples with ITO-rod, SWCNT/ITO-rod, ITO-rod/SWCNT, and SWCNT/ITO-rod/SWCNT structures for comparison. As a result, the sample with SWCNT/ITO-rod/SWCNT structures showed the highest transmittance over 90% at 280 nm and the highest Ohmic behavior (with sheet resistance of 5.33 kΩ/□) in the current–voltage characteristic curves. - Highlights: • Transparent conductive oxide (TCO) electrodes are proposed for UV light-emitting diodes. • These TCO electrodes are based on evaporated indium tin oxide (ITO)-rods. • Single walled carbon nanotube (SWCNT) layers are used as a current spreading layer. • The proposed TCO electrode structures show more than 90% transmittance at 280 nm

  15. Polyaniline modified graphene and carbon nanotube composite electrode for asymmetric supercapacitors of high energy density

    Science.gov (United States)

    Cheng, Qian; Tang, Jie; Shinya, Norio; Qin, Lu-Chang

    2013-11-01

    Graphene and single-walled carbon nanotube (CNT) composites are explored as the electrodes for supercapacitors by coating polyaniline (PANI) nano-cones onto the graphene/CNT composite to obtain graphene/CNT-PANI composite electrode. The graphene/CNT-PANI electrode is assembled with a graphene/CNT electrode into an asymmetric pseudocapacitor and a highest energy density of 188 Wh kg-1 and maximum power density of 200 kW kg-1 are achieved. The structure and morphology of the graphene/CNT composite and the PANI nano-cone coatings are characterized by both scanning electron microscopy and transmission electron microscopy. The excellent performance of the assembled supercapacitors is also discussed and it is attributed to (i) effective utilization of the large surface area of the three-dimensional network structure of graphene-based composite, (ii) the presence of CNT in the composite preventing graphene from re-stacking, and (ii) uniform and vertically aligned PANI coating on graphene offering increased electrical conductivity.

  16. Oxidized multi walled carbon nanotubes for improving the electrocatalytic activity of a benzofuran derivative modified electrode

    Directory of Open Access Journals (Sweden)

    Mohammad Mazloum-Ardakani

    2016-01-01

    Full Text Available In the present paper, the use of a novel carbon paste electrode modified by 7,8-dihydroxy-3,3,6-trimethyl-3,4-dihydrodibenzo[b,d]furan-1(2H-one (DTD and oxidized multi-walled carbon nanotubes (OCNTs is described for determination of levodopa (LD, acetaminophen (AC and tryptophan (Trp by a simple and rapid method. At first, the electrochemical behavior of DTD is studied, then, the mediated oxidation of LD at the modified electrode is investigated. At the optimum pH of 7.4, the oxidation of LD occurs at a potential about 330 mV less positive than that of an unmodified carbon paste electrode. Based on differential pulse voltammetry (DPV, the oxidation current of LD exhibits a linear range between 1.0 and 2000.0 μM of LD with a detection limit (3σ of 0.36 μM. DPV was also used for simultaneous determination of LD, AC and Trp at the modified electrode. Finally, the proposed electrochemical sensor was used for determinations of these substances in human serum sample.

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

    International Nuclear Information System (INIS)

    Chang, Wen-Teng; Yang, Fu-Siang

    2015-01-01

    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

  18. 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.

  19. Electrochemical Treatment of Wastewater Containing Mixed Reactive Dyes Using Carbon Nanotube Modified Cathode Electrodes

    Directory of Open Access Journals (Sweden)

    Nader Djafarzadeh

    2016-11-01

    Full Text Available Nowadays, advanced electrochemical oxidation processes are promising methods for the treatment of wastewaters containing organic dyes. One of these methods is the Electro-Fenton (EF technique in which an electrical current is applied to the cathode and anode electrodes to promote electrochemical reactions that generate hydroxyl radicals which mineralize organic pollutants and remove them from wastewater. To carry out the Electro-Fenton process iIn this work, the carbon paper (CP electrode was initially modified with carbon nanotubes (CNT to produce the CP-CNT electrode which was used as the cathode to remove a mixture of organic dyestuff (containing Reactive Blue 69, Reactive Red 195, and Reactive Yellow 84 from wastewaters. Comparison of the two types of cathode electrodes (i.e., CNT and the modified CP-CNT showed that the CP-CNT outperformed the CP electrode. The EF process was employed to treat 500 ml of a mixture of dyes (50 mg/L of each dye containing sodium soulfate and Fe+3 ions. The results revealed that the highest color removal efficiency was achieved when a current of 300 mA was applied for 210 min. COD measurments were used to calculate the effective current and power consumption. It was found that the 300 mA current applied over a period of 210 min yielded the highest effective current and the lowest power consumption. The amount of dyes mineralized by the EF process in the dye solution indicated that 78% of the initial COD had been removed under the above conditions. It may be concluded that the Electro-Fenton process can be successfully used for the treatment of wastewaters containing mixtures of dye pollutants. Cathode electrode type, electrical current, and electrolysis duration were identified as the parameters affecting the process.

  20. Efficient Photocatalytic Degradation of Rhodamine B Dye by Aligned Arrays of Self-Assembled Hydrogen Titanate Nanotubes

    Directory of Open Access Journals (Sweden)

    Sriparna Chatterjee

    2014-01-01

    Full Text Available We show that an aligned array of hydrothermally grown, multiwalled hydrogen titanate (H2Ti3O7 nanotubes—anchored to both faces of a metallic Ti foil—acts as an efficient photocatalyst. We studied the degradation of rhodamine B dye in the presence of the nanostructured photocatalyst under UV irradiation, by monitoring the optical absorption of the dye. Rhodamine B was chosen as a representative—and particularly harmful—industrial pollutant dye. The inner and outer diameters of the H2Ti3O7 nanotubes were 5 nm and 10 nm, respectively. The nanotube array catalyst is recyclable and structurally stable. Most importantly, it shows comparable or higher photodecomposition rate constant than those of both H2Ti3O7 nanotube powder and P-25 (Degussa. The enhanced photocatalytic performance may be ascribed to the nanotube array having a superhydrophilic surface with a high accessible surface area.

  1. Orthogonal electrode catheter array for mapping of endocardial focal site of ventricular activation

    Energy Technology Data Exchange (ETDEWEB)

    Desai, J.M.; Nyo, H.; Vera, Z.; Seibert, J.A.; Vogelsang, P.J. (Division of Cardiovascular Medicine, University of California, School of Medicine, Davis (USA))

    1991-04-01

    Precise location of the endocardial site of origin of ventricular tachycardia may facilitate surgical and catheter ablation of this arrhythmia. The endocardial catheter mapping technique can locate the site of ventricular tachycardia within 4-8 cm2 of the earliest site recorded by the catheter. This report describes an orthogonal electrode catheter array (OECA) for mapping and radiofrequency ablation (RFA) of endocardial focal site of origin of a plunge electrode paced model of ventricular activation in dogs. The OECA is an 8 F five pole catheter with four peripheral electrodes and one central electrode (total surface area 0.8 cm{sup 2}). In eight mongrel dogs, mapping was performed by arbitrarily dividing the left ventricle (LV) into four segments. Each segment was mapped with OECA to find the earliest segment. Bipolar and unipolar electrograms were obtained. The plunge electrode (not visible on fluoroscopy) site was identified by the earliest wave front arrival times of -30 msec or earlier at two or more electrodes (unipolar electrograms) with reference to the earliest recorded surface ECG (I, AVF, and V1). Validation of the proximity of the five electrodes of the OECA to the plunge electrode was performed by digital radiography and RFA. Pathological examination was performed to document the proximity of the OECA to the plunge electrode and also for the width, depth, and microscopic changes of the ablation. To find the segment with the earliest LV activation a total of 10 {plus minus} 3 (mean {plus minus} SD) positions were mapped. Mean arrival times at the two earlier electrodes were -39 {plus minus} 4 msec and -35 {plus minus} 3 msec. Digital radiography showed the plunge electrode to be within the area covered by all five electrodes in all eight dogs. The plunge electrode was within 1 cm2 area of the region of RFA in all eight dogs.

  2. Design, simulation and characterization of a MEMS inertia switch with flexible CNTs/Cu composite array layer between electrodes for prolonging contact time

    International Nuclear Information System (INIS)

    Wang, Yang; Yang, Zhuoqing; Xu, Qiu; Chen, Wenguo; Ding, Guifu; Zhao, Xiaolin

    2015-01-01

    This paper reports an inertia switch with a flexible carbon nanotubes/copper (CNTs/Cu) composite array layer between movable and fixed electrodes, which achieves a longer contact time compared to the traditional design using rigid-to-rigid impact between electrodes. The CNTs/Cu layer is fabricated using the composite electroplating method, and the whole device is completed by multi-layer metal electroplating based on the micro-electro-mechanical systems (MEMS) process. The dynamic responses of the designed inertia switch and the contact impact between a single CNT and a fixed electrode/another CNT have both been simulated by the ANSYS finite-element-method (FEM). It is shown that the contact time of the designed inertia switch is about 100 µs under the applied 80 g half-sine-shaped acceleration in the sensing direction. Finally, the fabricated MEMS inertia switch with the flexible CNTs/Cu composite array layer between electrodes has been evaluated by a dropping hammer system. The test contact time is about112 µs, which has a good agreement with the simulation and is much longer than that of the traditional design. (paper)

  3. Core-shell titanium dioxide-titanium nitride nanotube arrays with near-infrared plasmon resonances

    Science.gov (United States)

    Farsinezhad, Samira; Shanavas, Thariq; Mahdi, Najia; Askar, Abdelrahman M.; Kar, Piyush; Sharma, Himani; Shankar, Karthik

    2018-04-01

    Titanium nitride (TiN) is a ceramic with high electrical conductivity which in nanoparticle form, exhibits localized surface plasmon resonances (LSPRs) in the visible region of the solar spectrum. The ceramic nature of TiN coupled with its dielectric loss factor being comparable to that of gold, render it attractive for CMOS polarizers, refractory plasmonics, surface-enhanced Raman scattering and a whole host of sensing applications. We report core-shell TiO2-TiN nanotube arrays exhibiting LSPR peaks in the range 775-830 nm achieved by a simple, solution-based, low cost, large area-compatible fabrication route that does not involve laser-writing or lithography. Self-organized, highly ordered TiO2 nanotube arrays were grown by electrochemical anodization of Ti thin films on fluorine-doped tin oxide-coated glass substrates and then conformally coated with a thin layer of TiN using atomic layer deposition. The effects of varying the TiN layer thickness and thermal annealing on the LSPR profiles were also investigated. Modeling the TiO2-TiN core-shell nanotube structure using two different approaches, one employing effective medium approximations coupled with Fresnel coefficients, resulted in calculated optical spectra that closely matched the experimentally measured spectra. Modeling provided the insight that the observed near-infrared resonance was not collective in nature, and was mainly attributable to the longitudinal resonance of annular nanotube-like TiN particles redshifted due to the presence of the higher permittivity TiO2 matrix. The resulting TiO2-TiN core-shell nanotube structures also function as visible light responsive photocatalysts, as evidenced by their photoelectrochemical water-splitting performance under light emitting diode illumination using 400, 430 and 500 nm photons.

  4. Ti Porous Film-Supported NiCo₂S₄ Nanotubes Counter Electrode for Quantum-Dot-Sensitized Solar Cells.

    Science.gov (United States)

    Deng, Jianping; Wang, Minqiang; Song, Xiaohui; Yang, Zhi; Yuan, Zhaolin

    2018-04-17

    In this paper, a novel Ti porous film-supported NiCo₂S₄ nanotube was fabricated by the acid etching and two-step hydrothermal method and then used as a counter electrode in a CdS/CdSe quantum-dot-sensitized solar cell. Measurements of the cyclic voltammetry, Tafel polarization curves, and electrochemical impedance spectroscopy of the symmetric cells revealed that compared with the conventional FTO (fluorine doped tin oxide)/Pt counter electrode, Ti porous film-supported NiCo₂S₄ nanotubes counter electrode exhibited greater electrocatalytic activity toward polysulfide electrolyte and lower charge-transfer resistance at the interface between electrolyte and counter electrode, which remarkably improved the fill factor, short-circuit current density, and power conversion efficiency of the quantum-dot-sensitized solar cell. Under illumination of one sun (100 mW/cm²), the quantum-dot-sensitized solar cell based on Ti porous film-supported NiCo₂S₄ nanotubes counter electrode achieved a power conversion efficiency of 3.14%, which is superior to the cell based on FTO/Pt counter electrode (1.3%).

  5. Three-dimensional electrode array for brain slice culture

    DEFF Research Database (Denmark)

    Vazquez Rodriguez, Patricia

    Multielektroder arrays (MEA) er rækker af elektroder mest i mikrometer størrelse, som er blevet brugt i stor omfang til at stimulere og måle elektrisk aktivitet fra neuronale netværker. Brug af disse for at analysere hjerne slices (hjerneskiver) kan give indsigt i interaktioner mellem neuroner, e...

  6. A foldable electrode array for 3D recording of deep-seated abnormal brain cavities

    Science.gov (United States)

    Kil, Dries; De Vloo, Philippe; Fierens, Guy; Ceyssens, Frederik; Hunyadi, Borbála; Bertrand, Alexander; Nuttin, Bart; Puers, Robert

    2018-06-01

    Objective. This study describes the design and microfabrication of a foldable thin-film neural implant and investigates its suitability for electrical recording of deep-lying brain cavity walls. Approach. A new type of foldable neural electrode array is presented, which can be inserted through a cannula. The microfabricated electrode is specifically designed for electrical recording of the cavity wall of thalamic lesions resulting from stroke. The proof-of-concept is demonstrated by measurements in rat brain cavities. On implantation, the electrode array unfolds in the brain cavity, contacting the cavity walls and allowing recording at multiple anatomical locations. A three-layer microfabrication process based on UV-lithography and Reactive Ion Etching is described. Electrochemical characterization of the electrode is performed in addition to an in vivo experiment in which the implantation procedure and the unfolding of the electrode are tested and visualized. Main results. Electrochemical characterization validated the suitability of the electrode for in vivo use. CT imaging confirmed the unfolding of the electrode in the brain cavity and analysis of recorded local field potentials showed the ability to record neural signals of biological origin. Significance. The conducted research confirms that it is possible to record neural activity from the inside wall of brain cavities at various anatomical locations after a single implantation procedure. This opens up possibilities towards research of abnormal brain cavities and the clinical conditions associated with them, such as central post-stroke pain.

  7. Electrode property of single-walled carbon nanotubes in all-solid-state lithium ion battery using polymer electrolyte

    International Nuclear Information System (INIS)

    Sakamoto, Y.; Ishii, Y.; Kawasaki, S.

    2016-01-01

    Electrode properties of single-walled carbon nanotubes (SWCNTs) in an all-solid-state lithium ion battery were investigated using poly-ethylene oxide (PEO) solid electrolyte. Charge-discharge curves of SWCNTs in the solid electrolyte cell were successfully observed. It was found that PEO electrolyte decomposes on the surface of SWCNTs.

  8. Electrode property of single-walled carbon nanotubes in all-solid-state lithium ion battery using polymer electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Sakamoto, Y.; Ishii, Y.; Kawasaki, S., E-mail: kawasaki.shinji@nitech.ac.jp [Nagoya Institute of Technology, Gokiso, Showa, Nagoya, Aichi (Japan)

    2016-07-06

    Electrode properties of single-walled carbon nanotubes (SWCNTs) in an all-solid-state lithium ion battery were investigated using poly-ethylene oxide (PEO) solid electrolyte. Charge-discharge curves of SWCNTs in the solid electrolyte cell were successfully observed. It was found that PEO electrolyte decomposes on the surface of SWCNTs.

  9. 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.

  10. Thermally Stable and Electrically Conductive, Vertically Aligned Carbon Nanotube/Silicon Infiltrated Composite Structures for High-Temperature Electrodes.

    Science.gov (United States)

    Zou, Qi Ming; Deng, Lei Min; Li, Da Wei; Zhou, Yun Shen; Golgir, Hossein Rabiee; Keramatnejad, Kamran; Fan, Li Sha; Jiang, Lan; Silvain, Jean-Francois; Lu, Yong Feng

    2017-10-25

    Traditional ceramic-based, high-temperature electrode materials (e.g., lanthanum chromate) are severely limited due to their conditional electrical conductivity and poor stability under harsh circumstances. Advanced composite structures based on vertically aligned carbon nanotubes (VACNTs) and high-temperature ceramics are expected to address this grand challenge, in which ceramic serves as a shielding layer protecting the VACNTs from the oxidation and erosive environment, while the VACNTs work as a conductor. However, it is still a great challenge to fabricate VACNT/ceramic composite structures due to the limited diffusion of ceramics inside the VACNT arrays. In this work, we report on the controllable fabrication of infiltrated (and noninfiltrated) VACNT/silicon composite structures via thermal chemical vapor deposition (CVD) [and laser-assisted CVD]. In laser-assisted CVD, low-crystalline silicon (Si) was quickly deposited at the VACNT subsurfaces/surfaces followed by the formation of high-crystalline Si layers, thus resulting in noninfiltrated composite structures. Unlike laser-assisted CVD, thermal CVD activated the precursors inside and outside the VACNTs simultaneously, which realized uniform infiltrated VACNT/Si composite structures. The growth mechanisms for infiltrated and noninfiltrated VACNT/ceramic composites, which we attributed to the different temperature distributions and gas diffusion mechanism in VACNTs, were investigated. More importantly, the as-farbicated composite structures exhibited excellent multifunctional properties, such as excellent antioxidative ability (up to 1100 °C), high thermal stability (up to 1400 °C), good high velocity hot gas erosion resistance, and good electrical conductivity (∼8.95 Sm -1 at 823 K). The work presented here brings a simple, new approach to the fabrication of advanced composite structures for hot electrode applications.

  11. High-performance Li-ion Sn anodes with enhanced electrochemical properties using highly conductive TiN nanotubes array as a 3D multifunctional support

    Science.gov (United States)

    Pu, Jun; Du, Hongxiu; Wang, Jian; Wu, Wenlu; Shen, Zihan; Liu, Jinyun; Zhang, Huigang

    2017-08-01

    High capacity electrodes are demanded to increase the energy and power density of lithium ion batteries. However, the cycling and rate properties are severely affected by the large volume changes caused by the lithium insertion and extraction. Structured electrodes with mechanically stable scaffolds are widely developed to mitigate the adverse effects of volume changes. Tin, as a promising anode material, receives great attentions because of its high theoretic capacity. There is a critical value of tin particle size above which tin anodes readily crack, leading to low cyclability. The electrode design using mechanical scaffolds must retain tin particles below the critical size and concurrently enable high volumetric capacity. It is a challenge to guarantee the critical size for high cyclability and space utilization for high volumetric capacity. This study provides a highly conductive TiN nanotubes array with submicron diameters, which enable thin tin coating without sacrificing the volumetric capacity. Such a structured electrode delivers a capacity of 795 mAh gSn-1 (Sn basis) and 1812 mAh cmel-3 (electrode basis). The long-term cycling shows only 0.04% capacity decay per cycle.

  12. Multi-electrode array technologies for neuroscience and cardiology

    Science.gov (United States)

    Spira, Micha E.; Hai, Aviad

    2013-02-01

    At present, the prime methodology for studying neuronal circuit-connectivity, physiology and pathology under in vitro or in vivo conditions is by using substrate-integrated microelectrode arrays. Although this methodology permits simultaneous, cell-non-invasive, long-term recordings of extracellular field potentials generated by action potentials, it is 'blind' to subthreshold synaptic potentials generated by single cells. On the other hand, intracellular recordings of the full electrophysiological repertoire (subthreshold synaptic potentials, membrane oscillations and action potentials) are, at present, obtained only by sharp or patch microelectrodes. These, however, are limited to single cells at a time and for short durations. Recently a number of laboratories began to merge the advantages of extracellular microelectrode arrays and intracellular microelectrodes. This Review describes the novel approaches, identifying their strengths and limitations from the point of view of the end users -- with the intention to help steer the bioengineering efforts towards the needs of brain-circuit research.

  13. A nanostructured electrode of IrOx foil on the carbon nanotubes for supercapacitors

    Science.gov (United States)

    Chen, Yi-Min; Cai, Jhen-Hong; Huang, Ying-Sheng; Lee, Kuei-Yi; Tsai, Dah-Shyang; Tiong, Kwong-Kau

    2011-09-01

    IrOx nanofoils (IrOxNF) of high surface area are sputtered on multi-wall carbon nanotubes (CNT) in the preparation of a structured electrode on a stainless steel (SUS) substrate for supercapacitor applications. This IrOx/CNT/SUS electrode is featured with intriguing IrOx curved foils of 2-3 nm in thickness and 400-500 nm in height, grown on top of the vertically aligned CNT film with a tube diameter of ~ 40 nm. These nanofoils are moderately oxidized during reactive sputtering and appeared translucent under the electron microscope. Detailed structural analysis shows that they are comprised of contiguous grains of iridium metal, iridium dioxide, and glassy iridium oxide. Considerable Raman line broadening is also evidenced for the attributed nanosized iridium oxides. Two capacitive properties of the electrode are significantly enhanced with addition of the curved IrOx foils. First, IrOxNF reduces the electrode Ohmic resistance, which was measured at 3.5 Ω cm2 for the CNT/SUS and 2.5 Ω cm2 for IrOxNF/CNT/SUS using impedance spectroscopy. Second, IrOxNF raises the electrode capacitance from 17.7 F g - 1 (CNT/SUS) to 317 F g - 1 (IrOx/CNT/SUS), measured with cyclic voltammetry. This notable increase is further confirmed by the galvanostatic charge/discharge experiment, measuring 370 F g - 1 after 2000 uninterrupted cycles between - 1.0 and 0.0 V (versus Ag/AgCl).

  14. A nanostructured electrode of IrO{sub x} foil on the carbon nanotubes for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yi-Min; Cai, Jhen-Hong; Huang, Ying-Sheng; Lee, Kuei-Yi [Department of Electronic Engineering, National Taiwan University of Science and Technology, 43 Keelung Road, Section 4, Taipei 106, Taiwan (China); Tsai, Dah-Shyang [Department of Chemical Engineering, National Taiwan University of Science and Technology, 43 Keelung Road, Section 4, Taipei 106, Taiwan (China); Tiong, Kwong-Kau, E-mail: ysh@mail.ntust.edu.tw [Department of Electrical Engineering, National Taiwan Ocean University, Keelung 202, Taiwan (China)

    2011-09-02

    IrO{sub x} nanofoils (IrO{sub x}NF) of high surface area are sputtered on multi-wall carbon nanotubes (CNT) in the preparation of a structured electrode on a stainless steel (SUS) substrate for supercapacitor applications. This IrO{sub x}/CNT/SUS electrode is featured with intriguing IrO{sub x} curved foils of 2-3 nm in thickness and 400-500 nm in height, grown on top of the vertically aligned CNT film with a tube diameter of {approx} 40 nm. These nanofoils are moderately oxidized during reactive sputtering and appeared translucent under the electron microscope. Detailed structural analysis shows that they are comprised of contiguous grains of iridium metal, iridium dioxide, and glassy iridium oxide. Considerable Raman line broadening is also evidenced for the attributed nanosized iridium oxides. Two capacitive properties of the electrode are significantly enhanced with addition of the curved IrO{sub x} foils. First, IrO{sub x}NF reduces the electrode Ohmic resistance, which was measured at 3.5 {Omega} cm{sup 2} for the CNT/SUS and 2.5 {Omega} cm{sup 2} for IrO{sub x}NF/CNT/SUS using impedance spectroscopy. Second, IrO{sub x}NF raises the electrode capacitance from 17.7 F g{sup -1} (CNT/SUS) to 317 F g{sup -1} (IrO{sub x}/CNT/SUS), measured with cyclic voltammetry. This notable increase is further confirmed by the galvanostatic charge/discharge experiment, measuring 370 F g{sup -1} after 2000 uninterrupted cycles between - 1.0 and 0.0 V (versus Ag/AgCl).

  15. 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

  16. Sol-gel auto-combustion synthesis of hydroxyapatite nanotubes array in porous alumina template

    International Nuclear Information System (INIS)

    Yuan Yuan; Liu Changsheng; Zhang Yuan; Shan Xiaoqian

    2008-01-01

    In this paper, an array of highly ordered hydroxyapatite (HAP) nanotubes was synthesized by sol-gel auto-combustion method with porous anodic aluminum oxide (AAO) template for the first time. Based on thermogravimetry (DTA/TG), Fourier transform infrared (FTIR) and X-ray diffraction (XRD), the dried gel, derived from the sol solution with Ca(NO 3 ) 2 .4H 2 O and PO(CH 3 O) 3 as precursors and ethylene glycol as the polymeric matrix, exhibited a typical self-propagating combustion behavior at low temperature, directly resulting in hexagonal crystalline HAP materials. The resultant HAP arrays fabricated from the above sol-gel in the AAO template were uniformly distributed, highly ordered nanotubes with uniform length and diameter according to the observations of scanning electron microscopy (SEM) and transmission electron microscope (TEM). The electron diffraction (ED), XRD and X-ray photoelectron spectroscopy (XPS) survey proved the formation of HAP phase with polycrystalline structure in the AAO template. Based on these results, a potential mechanism of 'an auto-combustion from dried gel to nanoparticles and a subsequent in situ reaction from nanoparticles to nanotubes' was proposed

  17. Hydrogen peroxide biosensor based on microperoxidase-11 immobilized in a silica cavity array electrode.

    Science.gov (United States)

    Tian, Shu; Zhou, Qun; Gu, Zhuomin; Gu, Xuefang; Zhao, Lili; Li, Yan; Zheng, Junwei

    2013-03-30

    Hydrogen peroxide biosensor based on the silica cavity array modified indium-doped tin oxide (ITO) electrode was constructed. An array of silica microcavities was fabricated by electrodeposition using the assembled polystyrene particles as template. Due to the resistance gradient of the silica cavity structure, the silica cavity exhibits a confinement effect on the electrochemical reactions, making the electrode function as an array of "soft" microelectrodes. The covalently immobilized microperoxidase-11(MP-11) inside these SiO2 cavities can keep its physiological activities, the electron transfer between the MP-11 and electrode was investigated through electrochemical method. The cyclic voltammetric curve shows a quasi-reversible electrochemical redox behavior with a pair of well-defined redox peaks, the cathodic and anodic peaks are located at -0.26 and -0.15V. Furthermore, the modified electrode exhibits high electrocatalytic activity toward the reduction of hydrogen peroxide and also shows good analytical performance for the amperometric detection of H2O2 with a linear range from 2×10(-6) to 6×10(-4)M. The good reproducibility and long-term stability of this novel electrode not only offer an opportunity for the detection of H2O2 in low concentration, but also provide a platform to construct various biosensors based on many other enzymes. Copyright © 2013 Elsevier B.V. All rights reserved.

  18. Photoelectrocatalytic activity of a hydrothermally grown branched Zno nanorod-array electrode for paracetamol degradation.

    Science.gov (United States)

    Lin, Chin Jung; Liao, Shu-Jun; Kao, Li-Cheng; Liou, Sofia Ya Hsuan

    2015-06-30

    Hierarchical branched ZnO nanorod (B-ZnR) arrays as an electrode for efficient photoelectrocatalytic degradation of paracetamol were grown on fluorine-doped tin oxide substrates using a solution route. The morphologic and structural studies show the ZnO trunks are single-crystalline hexagonal wurtzite ZnO with a [0001] growth direction and are densely covered by c-axis-oriented ZnO branches. The obvious enhancement in photocurrent response of the B-ZnR electrode was obtained than that in the ZnO nanoparticle (ZnO NP) electrode. For the photoelectrocatalytic degradation of paracetamol in 20 h, the conversion fraction of the drug increased from 32% over ZnO NP electrode to 62% over B-ZnR arrays with about 3-fold increase in initial reaction rate. The light intensity-dependent photoelectrocatalytic experiment indicated that the superior performance over the B-ZnR electrode was mainly ascribed to the increased specific surface area without significantly sacrificing the charge transport and pollutant diffusion efficiencies. Two aromatic intermediate compounds were observed and eventually converted into harmless carboxylic acids and ammonia. Hierarchical tree-like ZnO arrays can be considered effective alternatives to improve photoelectro degradation rates without the need for expensive additives. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Reliability of spring interconnects for high channel-count polyimide electrode arrays

    Science.gov (United States)

    Khan, Sharif; Ordonez, Juan Sebastian; Stieglitz, Thomas

    2018-05-01

    Active neural implants with a high channel-count need robust and reliable operational assembly for the targeted environment in order to be classified as viable fully implantable systems. The discrete functionality of the electrode array and the implant electronics is vital for intact assembly. A critical interface exists at the interconnection sites between the electrode array and the implant electronics, especially in hybrid assemblies (e.g. retinal implants) where electrodes and electronics are not on the same substrate. Since the interconnects in such assemblies cannot be hermetically sealed, reliable protection against the physiological environment is essential for delivering high insulation resistance and low defusibility of salt ions, which are limited in complexity by current assembly techniques. This work reports on a combination of spring-type interconnects on a polyimide array with silicone rubber gasket insulation for chronically active implantable systems. The spring design of the interconnects on the backend of the electrode array compensates for the uniform thickness of the sandwiched gasket during bonding in assembly and relieves the propagation of extrinsic stresses to the bulk polyimide substrate. The contact resistance of the microflex-bonded spring interconnects with the underlying metallized ceramic test vehicles and insulation through the gasket between adjacent contacts was investigated against the MIL883 standard. The contact and insulation resistances remained stable in the exhausting environmental conditions.

  20. Reductive dehalogenation of haloacetic acids by hemoglobin-loaded carbon nanotube electrode.

    Science.gov (United States)

    Li, Yu-Ping; Cao, Hong-Bin; Zhang, Yi

    2007-01-01

    Hemoglobin (Hb) was immobilized on carbon nanotube (CNT) electrode to catalyze the dehalogenation of haloacetic acids (HAAs). FTIR and UV measurements were performed to investigate the activity-keep of Hb after immobilization on CNT. The electrocatalytic behaviors of the Hb-loaded electrode for the dehalogenation of HAAs were studied by cyclic voltammmetry and constant-potential electrolysis technique. An Hb-loaded packed-bed flow reactor was also constructed for bioelectrocatalytic dehalogenation of HAAs. The results showed that Hb retained its nature, the essential features of its native secondary structure, and its biocatalytic activity after immobilization on CNT. Chloroacetic acids and bromoacetic acids could be dehalogenated completely with Hb catalysis through a stepwise dehalogenation process at -0.400V (vs. saturated calomel electrode (SCE)) and -0.200V (vs. SCE), respectively. The removal of 10.5mM trichloroacetic acid and dichloroacetic acid is ca. 97% and 63%, respectively, with electrolysis for 300min at -0.400V (vs. SCE) using the Hb-loaded packed-bed flow reactor, and almost 100% of tribromoacetic acid and dibromoacetic acid was removed with electrolysis for 40min at -0.200V (vs. SCE). The average current efficiency of Hb-catalytic dehalogenation almost reaches 100%.

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

    Science.gov (United States)

    Burblies, Niklas; Schulze, Jennifer; 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.

  2. Multidirectional flexible force sensors based on confined, self-adjusting carbon nanotube arrays

    Science.gov (United States)

    Lee, J.-I.; Pyo, Soonjae; Kim, Min-Ook; Kim, Jongbaeg

    2018-02-01

    We demonstrate a highly sensitive force sensor based on self-adjusting carbon nanotube (CNT) arrays. Aligned CNT arrays are directly synthesized on silicon microstructures by a space-confined growth technique which enables a facile self-adjusting contact. To afford flexibility and softness, the patterned microstructures with the integrated CNTs are embedded in polydimethylsiloxane structures. The sensing mechanism is based on variations in the contact resistance between the facing CNT arrays under the applied force. By finite element analysis, proper dimensions and positions for each component are determined. Further, high sensitivities up to 15.05%/mN of the proposed sensors were confirmed experimentally. Multidirectional sensing capability could also be achieved by designing multiple sets of sensing elements in a single sensor. The sensors show long-term operational stability, owing to the unique properties of the constituent CNTs, such as outstanding mechanical durability and elasticity.

  3. High performance flexible pH sensor based on polyaniline nanopillar array electrode.

    Science.gov (United States)

    Yoon, Jo Hee; Hong, Seok Bok; Yun, Seok-Oh; Lee, Seok Jae; Lee, Tae Jae; Lee, Kyoung G; Choi, Bong Gill

    2017-03-15

    Flexible pH sensor technologies have attracted a great deal of attention in many applications, such as, wearable health care devices and monitors for chemical and biological processes. Here, we fabricated flexible and thin pH sensors using a two electrode configuration comprised of a polyaniline nanopillar (PAN) array working electrode and an Ag/AgCl reference electrode. In order to provide nanostructure, soft lithography using a polymeric blend was employed to create a flexible nanopillar backbone film. Polyaniline-sensing materials were deposited on a patterned-nanopillar array by electrochemical deposition. The pH sensors produced exhibited a near-Nernstian response (∼60.3mV/pH), which was maintained in a bent state. In addition, pH sensors showed other excellent sensor performances in terms of response time, reversibility, repeatability, selectivity, and stability. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Silver-nickel oxide core-shell nanoparticle array electrode with enhanced lithium-storage performance

    International Nuclear Information System (INIS)

    Zhao, Wenjia; Du, Ning; Zhang, Hui; Yang, Deren

    2015-01-01

    We demonstrate the synthesis of Ag-NiO core-shell nanoparticle arrays via a one-step solution-immersion process and subsequent RF-sputtering technique. The Ag nanoparticle arrays on copper substrate are firstly prepared by a displacement reaction at mild temperature of 303K. Then, a NiO layer is deposited onto the surface of the Ag nanoparticles via RF-sputtering technique. When evaluated as an anode for lithium-ion batteries, the Ag-NiO core-shell electrode shows higher capacity and better cycling performance than the planar NiO electrode. The in-situ synthesized Ag nanoparticles can enhance the interfacial strength between the active material and substrate, andimprove the electrical conductivity of the electrode, which may be responsible for the enhanced performance

  5. High Density Nano-Electrode Array for Radiation Detection

    International Nuclear Information System (INIS)

    Misra, Mano

    2010-01-01

    Bulk single crystals of Cd 1-x Zn x Te (x=0.04 to x=0.2) compound semiconductor is used for room temperature radiation detection. The production of large volume of Cd 1-x Zn x Te with low defect density is expensive. As a result there is a growing research interest in the production of nanostructured compound semiconductors such as Cd 1-x Zn x Te in an electrochemical route. In this investigation, Cd 1-x Zn x Te ternary compound semiconductor, referred as CZT, was electrodeposited in the form of nanowires onto a TiO 2 nanotubular template from propylene carbonate as the non-aqueous electrolyte, using a pulse-reverse electrodeposition process at 130 C. The template acted as a support in growing ordered nanowire of CZT which acts as a one dimensional conductor. Cyclic Voltammogram (CV) studies were conducted in determining the potentials for the growth of nanowires of uniform stoichiometry. The morphologies and composition of CZT were characterized by using SEM, TEM and XRD. The STEM mapping carried out on the nanowires showed the uniform distribution of Cd, Zn and Te elements. TEM image showed that the nanowires were polycrystalline in nature. The Mott-Schottky analysis carried on the nanowires showed that the nanowires were a p-type semiconductor. The carrier density, band gap and resistivity of the Cd 0.9 Zn 0.1 Te nanowires were 4.29 x 10 13 cm -3 , 1.56 eV and 2.76 x 10 11 (Omega)-cm respectively. The high resistivity was attributed to the presence of deep defect states such as cadmium vacancies or Te antisites which were created by the anodic cycle of the pulse-reverse electrodeposition process. Stacks of series connected CZT nanowire arrays were tested with different bias potentials. The background current was in the order of tens of picoamperes. When exposed to radiation source Amerecium-241 (60 KeV, 4 (micro)Ci), the stacked CZT nanowires arrays showed sensing behavior. The sensitivity of the nanowire arrays increased as the number of stacks increased. The

  6. High Density Nano-Electrode Array for Radiation Detection

    Energy Technology Data Exchange (ETDEWEB)

    Mano Misra

    2010-05-07

    Bulk single crystals of Cd1-xZnxTe (x=0.04 to x=0.2) compound semiconductor is used for room temperature radiation detection. The production of large volume of Cd1-xZnxTe with low defect density is expensive. As a result there is a growing research interest in the production of nanostructured compound semiconductors such as Cd1-xZnxTe in an electrochemical route. In this investigation, Cd1-xZnxTe ternary compound semiconductor, referred as CZT, was electrodeposited in the form of nanowires onto a TiO2 nanotubular template from propylene carbonate as the non-aqueous electrolyte, using a pulse-reverse electrodeposition process at 130 ºC. The template acted as a support in growing ordered nanowire of CZT which acts as a one dimensional conductor. Cyclic Voltammogram (CV) studies were conducted in determining the potentials for the growth of nanowires of uniform stoichiometry. The morphologies and composition of CZT were characterized by using SEM, TEM and XRD. The STEM mapping carried out on the nanowires showed the uniform distribution of Cd, Zn and Te elements. TEM image showed that the nanowires were polycrystalline in nature. The Mott-Schottky analysis carried on the nanowires showed that the nanowires were a p-type semiconductor. The carrier density, band gap and resistivity of the Cd0.9Zn0.1Te nanowires were 4.29x1013 cm-3, 1.56 eV and 2.76x1011Ω-cm respectively. The high resistivity was attributed to the presence of deep defect states such as cadmium vacancies or Te antisites which were created by the anodic cycle of the pulse-reverse electrodeposition process. Stacks of series connected CZT nanowire arrays were tested with different bias potentials. The background current was in the order of tens of picoamperes. When exposed to radiation source Amerecium-241 (60 KeV, 4 μCi), the stacked CZT nanowires arrays showed sensing behavior. The sensitivity of the nanowire arrays increased as the number of stacks increased. The preliminary results indicate that the

  7. Design of micro, flexible light-emitting diode arrays and fabrication of flexible electrodes

    International Nuclear Information System (INIS)

    Gao, Dan; Wang, Weibiao; Liang, Zhongzhu; Liang, Jingqiu; Qin, Yuxin; Lv, Jinguang

    2016-01-01

    In this study, we design micro, flexible light-emitting diode (LED) array devices. Using theoretical calculations and finite element simulations, we analyze the deformation of the conventional single electrode bar. Through structure optimization, we obtain a three-dimensional (3D), chain-shaped electrode structure, which has a greater bending degree. The optimized electrodes not only have a bigger bend but can also be made to spin. When the supporting body is made of polydimethylsiloxane (PDMS), the maximum bending degree of the micro, flexible LED arrays (4  ×  1 arrays) was approximately 230 µ m; this was obtained using the finite element method. The device (4  ×  1 arrays) can stretch to 15%. This paper describes the fabrication of micro, flexible LED arrays using microelectromechancial (MEMS) technology combined with electroplating technology. Specifically, the isolated grooves are made by dry etching which can isolate and protect the light-emitting units. A combination of MEMS technology and wet etching is used to fabricate the large size spacing. (paper)

  8. Intracellular Protein Delivery and Gene Transfection by Electroporation Using a Microneedle Electrode Array

    Science.gov (United States)

    Choi, Seong-O; Kim, Yeu-Chun; Lee, Jeong Woo; Park, Jung-Hwan

    2012-01-01

    The impact of many biopharmaceuticals, including protein- and gene-based therapies, has been limited by the need for better methods of delivery into cells within tissues. Here, we present intracellular delivery of molecules and transfection with plasmid DNA by electroporation using a novel microneedle electrode array designed for targeted treatment of skin and other tissue surfaces. The microneedle array is molded out of polylactic acid. Electrodes and circuitry required for electroporation are applied to the microneedle array surface by a new metal-transfer micromolding method. The microneedle array maintains mechanical integrity after insertion into pig cadaver skin and is able to electroporate human prostate cancer cells in vitro. Quantitative measurements show that increasing electroporation pulse voltage increases uptake efficiency of calcein and bovine serum albumin, whereas increasing pulse length has lesser effects over the range studied. Uptake of molecules by up to 50 % of cells and transfection of 12 % of cells with a gene for green fluorescent protein is demonstrated at high cell viability. We conclude that the microneedle electrode array is able to electroporate cells, resulting in intracellular uptake of molecules, and has potential applications to improve intracellular delivery of proteins, DNA and other biopharmaceuticals. PMID:22328093

  9. Flexible Supercapacitors Based on Polyaniline Arrays Coated Graphene Aerogel Electrodes.

    Science.gov (United States)

    Yang, Yu; Xi, Yunlong; Li, Junzhi; Wei, Guodong; Klyui, N I; Han, Wei

    2017-12-01

    Flexible supercapacitors(SCs) made by reduced graphene oxide (rGO)-based aerogel usually suffer from the low energy density, short cycle life and bad flexibility. In this study, a new, synthetic strategy was developed for enhancing the electrochemical performances of rGO aerogel-based supercapacitor via electrodeposition polyaniline arrays on the prepared ultralight rGO aerogel. The novel hybrid composites with coated polyaniline (PANI) arrays growing on the rGO surface can take full advantage of the rich open-pore and excellent conductivity of the crosslinking framework structure of 3D rGO aerogel and high capacitance contribution from the PANI. The obtained hybrid composites exhibit excellent electrochemical performance with a specific capacitance of 432 F g -1 at the current density of 1 A g -1 , robust cycling stability to maintain 85% after 10,000 charge/discharge cycles and high energy density of 25 W h kg -1 . Furthermore, the flexible all-solid-state supercapacitor have superior flexibility and outstanding stability under different bending states from the straight state to the 90° status. The high-performance flexible all-solid-state SCs together with the lighting tests demonstrate it possible for applications in portable electronics.

  10. Mapping the fine structure of cortical activity with different micro-ECoG electrode array geometries

    Science.gov (United States)

    Wang, Xi; Gkogkidis, C. Alexis; Iljina, Olga; Fiederer, Lukas D. J.; Henle, Christian; Mader, Irina; Kaminsky, Jan; Stieglitz, Thomas; Gierthmuehlen, Mortimer; Ball, Tonio

    2017-10-01

    Objective. Innovations in micro-electrocorticography (µECoG) electrode array manufacturing now allow for intricate designs with smaller contact diameters and/or pitch (i.e. inter-contact distance) down to the sub-mm range. The aims of the present study were: (i) to investigate whether frequency ranges up to 400 Hz can be reproducibly observed in µECoG recordings and (ii) to examine how differences in topographical substructure between these frequency bands and electrode array geometries can be quantified. We also investigated, for the first time, the influence of blood vessels on signal properties and assessed the influence of cortical vasculature on topographic mapping. Approach. The present study employed two µECoG electrode arrays with different contact diameters and inter-contact distances, which were used to characterize neural activity from the somatosensory cortex of minipigs in a broad frequency range up to 400 Hz. The analysed neural data were recorded in acute experiments under anaesthesia during peripheral electrical stimulation. Main results. We observed that µECoG recordings reliably revealed multi-focal cortical somatosensory response patterns, in which response peaks were often less than 1 cm apart and would thus not have been resolvable with conventional ECoG. The response patterns differed by stimulation site and intensity, they were distinct for different frequency bands, and the results of functional mapping proved independent of cortical vascular. Our analysis of different frequency bands exhibited differences in the number of activation peaks in topographical substructures. Notably, signal strength and signal-to-noise ratios differed between the two electrode arrays, possibly due to their different sensitivity for variations in spatial patterns and signal strengths. Significance. Our findings that the geometry of µECoG electrode arrays can strongly influence their recording performance can help to make informed decisions that maybe

  11. Hierarchical mesoporous nickel cobaltite nanoneedle/carbon cloth arrays as superior flexible electrodes for supercapacitors

    Science.gov (United States)

    2014-01-01

    Hierarchical mesoporous NiCo2O4 nanoneedle arrays on carbon cloth have been fabricated by a simple hydrothermal approach combined with a post-annealing treatment. Such unique array nanoarchitectures exhibit remarkable electrochemical performance with high capacitance and desirable cycle life at high rates. When evaluated as an electrode material for supercapacitors, the NiCo2O4 nanoneedle arrays supported on carbon cloth was able to deliver high specific capacitance of 660 F g-1 at current densities of 2 A g-1 in 2 M KOH aqueous solution. In addition, the composite electrode shows excellent mechanical behavior and long-term cyclic stability (91.8% capacitance retention after 3,000 cycles). The fabrication method presented here is facile, cost-effective, and scalable, which may open a new pathway for real device applications. PMID:24661431

  12. Photoelectrochemical oxidation of ibuprofen via Cu_2O-doped TiO_2 nanotube arrays

    International Nuclear Information System (INIS)

    Sun, Qiannan; Peng, Yen-Ping; Chen, Hanlin; Chang, Ken-Lin; Qiu, Yang-Neng; Lai, Shiau-Wu

    2016-01-01

    Highlights: • A p–n junction material was synthesized to enhance photocatalytic ability. • Cu_2O-doped TiO_2 nanotube arrays works as a photoanode in a PEC system. • Recombination of photo-generated holes and electrons were greatly reduced. • Synergetic effect was quantified in PEC degradation. • Recombination of photogenerated holes and electrons was greatly enhanced. - Abstract: A p–n junction based Cu_2O-doped TiO_2 nanotube arrays (Cu_2O-TNAs) were synthesized and used as a working anode in a photoelectrochemical (PEC) system. The results revealed that the Cu_2O-TNAs were dominated by the anatase phase and responded significantly to visible light. XPS analyses indicated that with an amount of 24.79% Cu doping into the structure, the band gap of Cu_2O-TNAs was greatly reduced. SEM images revealed that the supported TiO_2 nanotubes had diameters of approximately 80 nm and lengths of about 2.63 μm. Upon doping with Cu_2O, the TiO_2 nanotubes maintained their structural integrity, exhibiting no significant morphological change, favoring PEC applications. Under illumination, the photocurrent from Cu_2O/TNAs was 2.4 times larger than that from TNAs, implying that doping with Cu_2O significantly improved electron mobility by reducing the rate of recombination of electron-hole pairs. The EIS and Bode plot revealed that the estimated electron lifetimes, τ_e_l, of TNAs and Cu_2O/TNAs were 6.91 and 26.26 ms, respectively. The efficiencies of degradation of Ibuprofen by photoelectrochemical, photocatalytic (PC), electrochemical (EC) and photolytic (P) methods were measured.

  13. Rational control on floating catalysts for the growth of carbon nanotube assemblies: From vertically aligned carbon nanotube arrays to carbon nanotube films

    International Nuclear Information System (INIS)

    Chen, Hongyuan; Chen, Minghai; Zhang, Yongyi; Li, Qingwen

    2015-01-01

    Graphical abstract: - Highlights: • Floating catalyst CVD for the growth of CNT films and arrays was investigated. • The structure of CNT array grown in floating catalyst CVD was revealed. • Temperature was proved as a key for the growth of different CNT assemblies. • The increase of growth temperature induced the growth of single-walled CNT film. - Abstract: Floating catalyst chemical vapor deposition (FCCVD) has been widely used for the growth of various carbon nanotube (CNT) macrostructures, mainly including vertically aligned CNT (VACNT) arrays and none-woven CNT films. However, it is still unclear for the reason why these CNT macrostructures with largely different morphologies were received via the similar method. In this research, it revealed that the growth temperature largely affected the nucleation status of floating catalysts and thus controlled the morphologies of CNT macrostructures from VACNT arrays to none-woven CNT films. In low temperatures (below 800 °C), VACNTs were grown by bottom-up mechanism with several CNTs, but not one individual from bottom to up along the array height direction. Furthermore, VACNT arrays were only grown on some substrates that can induce iron atoms aggregating to catalyst particles with a suitable size. When increasing the growth temperature higher than 800 °C, more catalyst particles were nucleated in the gas flow, which induced the formation of none-woven CNT films composed of thin CNTs (single-walled CNTs and double-walled CNTs). This research was significative for understanding CNT growth mechanism via FCCVD process and the synthesis of different CNT macrostructures by this strategy.

  14. Rational control on floating catalysts for the growth of carbon nanotube assemblies: From vertically aligned carbon nanotube arrays to carbon nanotube films

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hongyuan; Chen, Minghai, E-mail: mhchen2008@sinano.ac.cn; Zhang, Yongyi; Li, Qingwen

    2015-10-30

    Graphical abstract: - Highlights: • Floating catalyst CVD for the growth of CNT films and arrays was investigated. • The structure of CNT array grown in floating catalyst CVD was revealed. • Temperature was proved as a key for the growth of different CNT assemblies. • The increase of growth temperature induced the growth of single-walled CNT film. - Abstract: Floating catalyst chemical vapor deposition (FCCVD) has been widely used for the growth of various carbon nanotube (CNT) macrostructures, mainly including vertically aligned CNT (VACNT) arrays and none-woven CNT films. However, it is still unclear for the reason why these CNT macrostructures with largely different morphologies were received via the similar method. In this research, it revealed that the growth temperature largely affected the nucleation status of floating catalysts and thus controlled the morphologies of CNT macrostructures from VACNT arrays to none-woven CNT films. In low temperatures (below 800 °C), VACNTs were grown by bottom-up mechanism with several CNTs, but not one individual from bottom to up along the array height direction. Furthermore, VACNT arrays were only grown on some substrates that can induce iron atoms aggregating to catalyst particles with a suitable size. When increasing the growth temperature higher than 800 °C, more catalyst particles were nucleated in the gas flow, which induced the formation of none-woven CNT films composed of thin CNTs (single-walled CNTs and double-walled CNTs). This research was significative for understanding CNT growth mechanism via FCCVD process and the synthesis of different CNT macrostructures by this strategy.

  15. SiN/bamboo like carbon nanotube composite electrodes for lithium ion rechargeable batteries

    International Nuclear Information System (INIS)

    Katar, Sri Lakshmi; Hernandez, Dionne; Biaggi Labiosa, Azlin; Mosquera-Vargas, Edgar; Fonseca, Luis; Weiner, Brad; Morell, Gerardo

    2010-01-01

    A dual stage technique employing hot filament chemical vapor deposition (HFCVD) and radio frequency sputtering was used to synthesize SiN/BCNTs (bamboo like carbon nanotubes) on copper substrates. The films were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Electron field emission studies (EFE), charge-discharge, and cyclic voltammetry. The comprehensive characterization is consistent with a nanolayer of amorphous SiN on BCNTs. Field emission experiments confirm the excellent contact of the SiN nanolayer with the surface of the BCNTs necessary for fabrication of a coin cell. Electrochemical testing shows that SiN/BCNT electrode can deliver an initial discharge capacity of 2000 mAh g -1 which is higher than the capacity of graphite and the reversible capacity after ten cycles is 300 mAh g -1 . The cyclic voltammetry results suggest good reversibility with Li during cycling.

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

    International Nuclear Information System (INIS)

    Ren, J.; Kang, T.F.; Xue, R.; Ge, C.N.; Cheng, S.Y.

    2011-01-01

    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)

  17. Preparation and Characterization of Carbon Nanotubes-Based Composite Electrodes for Electric Double Layer Capacitors

    International Nuclear Information System (INIS)

    Seo, Min Kang; Park, Soo Jin

    2012-01-01

    In this work, we prepared activated multi-walled carbon nanotubes/polyacrylonitrile (A-MWCNTs/C) composites by film casting and activation method. Electrochemical properties of the composites were investigated in terms of serving as MWCNTs-based electrode materials for electric double layer capacitors (EDLCs). As a result, the A-MWCNTs/C composites had much higher BET specific surface area, and pore volume, and lower volume ratio of micropores than those of pristine MWCNTs/PAN ones. Furthermore, some functional groups were added on the surface of the A-MWCNTs/C composites. The specific capacitance of the A-MWCNTs/C composites was more than 4.5 times that of the pristine ones at 0.1 V discharging voltage owing to the changes of the structure and surface characteristics of the MWCNTs by activation process

  18. High-efficiency supercapacitor electrodes of CVD-grown graphenes hybridized with multiwalled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Kalam, Amir Abul; Bae, Joon Ho [Dept. of Nano-physics, Gachon University, Seongnam (Korea, Republic of); Park, Soo Bin; Seo, Yong Ho [Nanotechnology and Advanced Material Engineering, HMC, and GRI, Sejong University, Seoul (Korea, Republic of)

    2015-08-15

    We demonstrate, for the first time, high-efficiency supercapacitors by utilizing chemical vapor deposition (CVD)-grown graphenes hybridized with multiwalled carbon nanotubes (CNTs). A single-layer graphene was grown by simple CVD growth method, and transferred to polyethylene terephthalate substrates. The bare graphenes were further hybridized with multiwalled CNTs by drop-coating CNTs on graphenes. The supercapacitors using bare graphenes and graphenes with CNTs revealed that graphenes with CNTs resulted in enhanced supercapacitor performances of 2.2- (the mass-specific capacitance) and 4.4-fold (the area-specific capacitance) of those of bare graphenes. Our strategy to improve electrochemical performance of CVD-grown graphenes is advantageous for large-scale graphene electrodes due to high electrical conductivity of CVD-grown graphenes and cost-effectiveness of using multiwalled CNTs as compared to conventional employment of single-walled CNTs.

  19. Transparent and flexible supercapacitors with single walled carbon nanotube thin film electrodes.

    Science.gov (United States)

    Yuksel, Recep; Sarioba, Zeynep; Cirpan, Ali; Hiralal, Pritesh; Unalan, Husnu Emrah

    2014-09-10

    We describe a simple process for the fabrication of transparent and flexible, solid-state supercapacitors. Symmetric electrodes made up of binder-free single walled carbon nanotube (SWCNT) thin films were deposited onto polydimethylsiloxane substrates by vacuum filtration followed by a stamping method, and solid-state supercapacitor devices were assembled using a gel electrolyte. An optical transmittance of 82% was found for 0.02 mg of SWCNTs, and a specific capacitance of 22.2 F/g was obtained. The power density can reach to 41.5 kW · kg(-1) and shows good capacity retention (94%) upon cycling over 500 times. Fabricated supercapacitors will be relevant for the realization of transparent and flexible devices with energy storage capabilities, displays and touch screens in particular.

  20. Preparation of graphene nanosheet/carbon nanotube/polyaniline composite as electrode material for supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Yan, Jun; Wei, Tong; Fan, Zhuangjun; Zhang, Milin; Shen, Xiande [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Qian, Weizhong; Wei, Fei [Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084 (China)

    2010-05-01

    Graphene nanosheet/carbon nanotube/polyaniline (GNS/CNT/PANI) composite is synthesized via in situ polymerization. GNS/CNT/PANI composite exhibits the specific capacitance of 1035 F g{sup -1} (1 mV s{sup -1}) in 6 M of KOH, which is a little lower than GNS/PANI composite (1046 F g{sup -1}), but much higher than pure PANI (115 F g{sup -1}) and CNT/PANI composite (780 F g{sup -1}). Though a small amount of CNTs (1 wt.%) is added into GNS, the cycle stability of GNS/CNT/PANI composite is greatly improved due to the maintenance of highly conductive path as well as mechanical strength of the electrode during doping/dedoping processes. After 1000 cycles, the capacitance decreases only 6% of initial capacitance compared to 52% and 67% for GNS/PANI and CNT/PANI composites. (author)

  1. 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

    2013-04-21

    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.

  2. High-efficiency supercapacitor electrodes of CVD-grown graphenes hybridized with multiwalled carbon nanotubes

    International Nuclear Information System (INIS)

    Kalam, Amir Abul; Bae, Joon Ho; Park, Soo Bin; Seo, Yong Ho

    2015-01-01

    We demonstrate, for the first time, high-efficiency supercapacitors by utilizing chemical vapor deposition (CVD)-grown graphenes hybridized with multiwalled carbon nanotubes (CNTs). A single-layer graphene was grown by simple CVD growth method, and transferred to polyethylene terephthalate substrates. The bare graphenes were further hybridized with multiwalled CNTs by drop-coating CNTs on graphenes. The supercapacitors using bare graphenes and graphenes with CNTs revealed that graphenes with CNTs resulted in enhanced supercapacitor performances of 2.2- (the mass-specific capacitance) and 4.4-fold (the area-specific capacitance) of those of bare graphenes. Our strategy to improve electrochemical performance of CVD-grown graphenes is advantageous for large-scale graphene electrodes due to high electrical conductivity of CVD-grown graphenes and cost-effectiveness of using multiwalled CNTs as compared to conventional employment of single-walled CNTs

  3. Indirect electrocatalytic degradation of cyanide at nitrogen-doped carbon nanotube electrodes.

    Science.gov (United States)

    Wiggins-Camacho, Jaclyn D; Stevenson, Keith J

    2011-04-15

    Nitrogen-doped carbon nanotube (N-CNT) mat electrodes exhibit high catalytic activity toward O(2) reduction, which can be exploited for the remediation of free cyanide (CN(-)). During the electrochemical O(2) reduction process, the hydroperoxide anion (HO(2)(-)) is formed and then reacts to chemically oxidize cyanide (CN(-)) to form cyanate (OCN(-)). The proposed electrochemical-chemical (EC) mechanism for CN(-) remediation at N-CNTs is supported by cyclic voltammetry and bulk electrolysis, and the formation of OCN(-) is confirmed via spectroscopic methods and electrochemical simulations. Our results indicate that by exploiting their catalytic behavior for O(2) reduction, N-CNTs can efficiently convert toxic CN(-) to the nontoxic OCN(-).

  4. Integrated ZnO nanotube arrays as efficient dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Xi, Y., E-mail: yxi6@cqu.edu.cn [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States); Wu, W.Z.; Fang, H. [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States); Hu, C.G. [Department of Applied Physics, Chongqing University, Chongqing 400044 (China)

    2012-07-15

    Highlights: Black-Right-Pointing-Pointer Tuning the reaction parameters, we got the best reaction conditions on ITO glass. Black-Right-Pointing-Pointer Introduce ZnO NTs design of photoanode featuring high aspect ratio structure. Black-Right-Pointing-Pointer The design strategy integrates the optical fibers or ITO with ZnO NTs grown. - Abstract: Zinc oxide (ZnO) is a wide band gap semiconducting material and has been considered as an alternative material in dye-sensitized solar cell (DSSC) applications. A high-performance nanotube (NT) photoanode must have a large surface area for dye adsorption in order to enhance conversion efficiency. In this work, the way of hydrothermally grown ZnO NT arrays on the indium tin oxide (ITO) substrate is presented by utilizing a systematic study. By adjusting the hydrothermal reaction parameters, we attained the optimizing reaction conditions on the ITO substrate. Moreover, ZnO NT arrays are introduced as a photoanode on various substrates, such as optical fiber and ITO glass, for DSSCs applications. We took the contrast test with conversion efficiency of the DSSC based on ZnO NT arrays versus ZnO nanowire arrays on the ITO substrate, which the DSSC based on ZnO NT arrays shows significantly enhanced power conversion efficiency. Furthermore, the conversion efficiency of DSSC based on the ZnO NT arrays grown on an optical fiber substrate is enhanced up to 1.44%.

  5. Extremely Black Vertically Aligned Carbon Nanotube Arrays for Solar Steam Generation.

    Science.gov (United States)

    Yin, Zhe; Wang, Huimin; Jian, Muqiang; Li, Yanshen; Xia, Kailun; Zhang, Mingchao; Wang, Chunya; Wang, Qi; Ma, Ming; Zheng, Quan-Shui; Zhang, Yingying

    2017-08-30

    The unique structure of a vertically aligned carbon nanotube (VACNT) array makes it behave most similarly to a blackbody. It is reported that the optical absorptivity of an extremely black VACNT array is about 0.98-0.99 over a large spectral range of 200 nm-200 μm, inspiring us to explore the performance of VACNT arrays in solar energy harvesting. In this work, we report the highly efficient steam generation simply by laminating a layer of VACNT array on the surface of water to harvest solar energy. It is found that under solar illumination the temperature of upper water can significantly increase with obvious water steam generated, indicating the efficient solar energy harvesting and local temperature rise by the thin layer of VACNTs. We found that the evaporation rate of water assisted by VACNT arrays is 10 times that of bare water, which is the highest ratio for solar-thermal-steam generation ever reported. Remarkably, the solar thermal conversion efficiency reached 90%. The excellent performance could be ascribed to the strong optical absorption and local temperature rise induced by the VACNT layer, as well as the ultrafast water transport through the VACNT layer due to the frictionless wall of CNTs. Based on the above, we further demonstrated the application of VACNT arrays in solar-driven desalination.

  6. Self-Adhesive and Capacitive Carbon Nanotube-Based Electrode to Record Electroencephalograph Signals From the Hairy Scalp.

    Science.gov (United States)

    Lee, Seung Min; Kim, Jeong Hun; Park, Cheolsoo; Hwang, Ji-Young; Hong, Joung Sook; Lee, Kwang Ho; Lee, Sang Hoon

    2016-01-01

    We fabricated a carbon nanotube (CNT)/adhesive polydimethylsiloxane (aPDMS) composite-based dry electroencephalograph (EEG) electrode for capacitive measuring of EEG signals. As research related to brain-computer interface applications has advanced, the presence of hairs on a patient's scalp has continued to present an obstacle to recorder EEG signals using dry electrodes. The CNT/aPDMS electrode developed here is elastic, highly conductive, self-adhesive, and capable of making conformal contact with and attaching to a hairy scalp. Onto the conductive disk, hundreds of conductive pillars coated with Parylene C insulation layer were fabricated. A CNT/aPDMS layer was attached on the disk to transmit biosignals to the pillar. The top of disk was designed to be solderable, which enables the electrode to connect with a variety of commercial EEG acquisition systems. The mechanical and electrical characteristics of the electrode were tested, and the performances of the electrodes were evaluated by recording EEGs, including alpha rhythms, auditory-evoked potentials, and steady-state visually-evoked potentials. The results revealed that the electrode provided a high signal-to-noise ratio with good tolerance for motion. Almost no leakage current was observed. Although preamplifiers with ultrahigh input impedance have been essential for previous capacitive electrodes, the EEGs were recorded here by directly connecting a commercially available EEG acquisition system to the electrode to yield high-quality signals comparable to those obtained using conventional wet electrodes.

  7. Nanocomposites of Graphene Nanosheets/Multiwalled Carbon Nanotubes as Electrodes for In-plane Supercapacitors

    International Nuclear Information System (INIS)

    Trigueiro, João Paulo C.; Lavall, Rodrigo L.; Silva, Glaura G.

    2016-01-01

    Flexible supercapacitors with large power and energy densities, long life cycles and good operational safety are necessary devices for various applications. In this work, we demonstrate the integration of a composite based on graphene nanosheets/multiwalled carbon nanotubes in an in-plane supercapacitor configuration by using a straightforward preparation involving the filtration of nanomaterials to produce an electrode film. Reduced graphene oxide (RGO) received 15 wt % carbon nanotubes to act as a conducting additive, which led to a flexible and transferable thin film (RGO/MW) with an average conductivity of 20.0 S cm −1 . Three ionic liquids were tested as electrolytes for the supercapacitor, among which 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMITFSI) was observed to exhibit the best performance. The specific capacitance of the supercapacitor based on RGO/MW-EMITFSI reached 153.7 F g −1 at a current density of 0.2 A g −1 and exhibited a capacitance retention of 88% after 2000 cycles. The maximum energy and power densities were calculated to be 41.3 Wh kg −1 and 3.5 kW kg −1 , respectively, for the RGO/MW-EMITFSI supercapacitor.

  8. Synergistic fusion of vertical graphene nanosheets and carbon nanotubes for high-performance supercapacitor electrodes.

    Science.gov (United States)

    Seo, Dong Han; Yick, Samuel; Han, Zhao Jun; Fang, Jing Hua; Ostrikov, Kostya Ken

    2014-08-01

    Graphene and carbon nanotubes (CNTs) are attractive electrode materials for supercapacitors. However, challenges such as the substrate-limited growth of CNTs, nanotube bundling in liquid electrolytes, under-utilized basal planes, and stacking of graphene sheets have so far impeded their widespread application. Here we present a hybrid structure formed by the direct growth of CNTs onto vertical graphene nanosheets (VGNS). VGNS are fabricated by a green plasma-assisted method to break down and reconstruct a natural precursor into an ordered graphitic structure. The synergistic combination of CNTs and VGNS overcomes the challenges intrinsic to both materials. The resulting VGNS/CNTs hybrids show a high specific capacitance with good cycling stability. The charge storage is based mainly on the non-Faradaic mechanism. In addition, a series of optimization experiments were conducted to reveal the critical factors that are required to achieve the demonstrated high supercapacitor performance. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Electrochemical impedance spectroscopy versus cyclic voltammetry for the electroanalytical sensing of capsaicin utilising screen printed carbon nanotube electrodes.

    Science.gov (United States)

    Randviir, Edward P; Metters, Jonathan P; Stainton, John; Banks, Craig E

    2013-05-21

    Screen printed carbon nanotube electrodes (SPEs) are explored as electroanalytical sensing platforms for the detection of capsaicin in both synthetic capsaicin solutions and capsaicin extracted from chillies and chilli sauces utilising both cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It is found that the technique which is most applicable to the electroanalytical detection of capsaicin depends upon the analyte concentration: for the case of low capsaicin concentrations, CV is a more appropriate method as capsaicin exhibits characteristic voltammetric waves of peak heights relevant to the capsaicin concentration; but for the case of high capsaicin concentrations where the voltammetric waves merge and migrate out of the potential window, EIS is shown to be a more appropriate technique, owing to the observed linear increases in R(ct) with increasing concentration. Furthermore, we explore different types of screen printed carbon nanotube electrodes, namely single- and multi- walled carbon nanotubes, finding that they are technique-specific: for the case of low capsaicin concentrations, single-walled carbon nanotube SPEs are preferable (SW-SPE); yet for the case of EIS at high capsaicin concentrations, multi-walled carbon nanotube SPEs (MW-SPE) are preferred, based upon analytical responses. The analytical performance of CV and EIS is applied to the sensing of capsaicin in grown chillies and chilli sauces and is critically compared to 'gold standard' HPLC analysis.

  10. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Xiangjun, Lu [College of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, Yudao Street 29, Nanjing 210016, Jiangsu (China); Dou Hui, E-mail: dh_msc@nuaa.edu.cn [College of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, Yudao Street 29, Nanjing 210016, Jiangsu (China); Bo, Gao [College of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, Yudao Street 29, Nanjing 210016, Jiangsu (China); Changzhou, Yuan [School of Materials Science and Engineering, Anhui University of Technology, Maanshan 243002 (China); Yang, Sudong; Liang, Hao; Laifa, Shen [College of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, Yudao Street 29, Nanjing 210016, Jiangsu (China); Zhang Xiaogang, E-mail: azhangxg@nuaa.edu.cn [College of Material Science and Engineering, Nanjing University of Aeronautics and Astronautics, Yudao Street 29, Nanjing 210016, Jiangsu (China)

    2011-05-30

    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{sup -1} at 0.1 A g{sup -1} and a good rate capability (49% capacity retention at 50 A g{sup -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.

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

    International Nuclear Information System (INIS)

    Lu Xiangjun; Dou Hui; Gao Bo; Yuan Changzhou; Yang, Sudong; Hao Liang; Shen Laifa; Zhang Xiaogang

    2011-01-01

    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. 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.

  14. Interface feature characterization and Schottky interfacial layer confirmation of TiO{sub 2} nanotube array film

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hongchao [State Key Laboratory of Powder Metallurgy, Central South University, 410083 Changsha (China); Chongyi Zhangyuan Tungsten Industry Corporation Limited, 341300 Ganzhou (China); Tang, Ningxin; Yang, Hongzhi; Leng, Xian [State Key Laboratory of Powder Metallurgy, Central South University, 410083 Changsha (China); Zou, Jianpeng, E-mail: zoujp@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, 410083 Changsha (China)

    2015-11-15

    Highlights: • Interfacial fusion of TiO{sub 2} nanotube film increases with annealing temperature. • Interface bonding force of the film increases with annealing temperature. • We report the forth stage of nanofibers formation in the growing mechanism. • TiO{sub 2} nanotubes grow from Schottky interface layer rather than from Ti substrate. • Schottky interface layer's thickness of 35–45 nm is half the diameter of nanotube. - Abstract: We report here characterization of the interfacial microstructure and properties of titanium dioxide (TiO{sub 2}) nanotube array films fabricated by anodization. Field effect scanning electron microscopy (FESEM), X-ray diffraction (XRD), nanoindentation, atomic force microscopy (AFM), selected area electron diffraction (SAED), and high-resolution transmission electron microscopy (HRTEM) were used to characterize the interface of the film. With increasing annealing temperature from 200 °C to 800 °C, the interfacial fusion between the film and the Ti substrate increased. The phase transformation of the TiO{sub 2} nanotube film from amorphous to anatase to rutile took place gradually; as the phase transformation progressed, the force needed to break the film increased. The growth of TiO{sub 2} nanotube arrays occurs in four stages: barrier layer formation, penetrating micropore formation, regular nanotube formation, and nanofiber formation. The TiO{sub 2} nanotubes grow from the Schottky interface layer rather than from the Ti substrate. The Schottky interface layer's thickness of 35–45 nm was identified as half the diameter of the corresponding nanotube, which shows good agreement to the Schottky interface layer growth model. The TiO{sub 2} nanotube film was amorphous and the Ti substrate was highly crystallized with many dislocation walls.

  15. Tungsten oxide@polypyrrole core-shell nanowire arrays as novel negative electrodes for asymmetric supercapacitors.

    Science.gov (United States)

    Wang, Fengmei; Zhan, Xueying; Cheng, Zhongzhou; Wang, Zhenxing; Wang, Qisheng; Xu, Kai; Safdar, Muhammad; He, Jun

    2015-02-11

    Among active pseudocapacitive materials, polypyrrole (PPy) is a promising electrode material in electrochemical capacitors. PPy-based materials research has thus far focused on its electrochemical performance as a positive electrode rather than as a negative electrode for asymmetric supercapacitors (ASCs). Here high-performance electrochemical supercapacitors are designed with tungsten oxide@PPy (WO3 @PPy) core-shell nanowire arrays and Co(OH)2 nanowires grown on carbon fibers. The WO3 @PPy core-shell nanowire electrode exhibits a high capacitance (253 mF/cm2) in negative potentials (-1.0-0.0 V). The ASCs packaged with CF-Co(OH)2 as a positive electrode and CF-WO3 @PPy as a negative electrode display a high volumetric capacitance up to 2.865 F/cm3 based on volume of the device, an energy density of 1.02 mWh/cm3 , and very good stability performance. These findings promote the application of PPy-based nanostructures as advanced negative electrodes for ASCs. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Fabrication of arrays of metal and metal oxide nanotubes by shadow evaporation.

    Science.gov (United States)

    Dickey, Michael D; Weiss, Emily A; Smythe, Elizabeth J; Chiechi, Ryan C; Capasso, Federico; Whitesides, George M

    2008-04-01

    This paper describes a simple technique for fabricating uniform arrays of metal and metal oxide nanotubes with controlled heights and diameters. The technique involves depositing material onto an anodized aluminum oxide (AAO) membrane template using a collimated electron beam evaporation source. The evaporating material enters the porous openings of the AAO membrane and deposits onto the walls of the pores. The membrane is tilted with respect to the column of evaporating material, so the shadows cast by the openings of the pores onto the inside walls of the pores define the geometry of the tubes. Rotation of the membrane during evaporation ensures uniform deposition inside the pores. After evaporation, dissolution of the AAO in base easily removes the template to yield an array of nanotubes connected by a thin backing of the same metal or metal oxide. The diameter of the pores dictates the diameter of the tubes, and the incident angle of evaporation determines the height of the tubes. Tubes up to approximately 1.5 mum in height and 20-200 nm in diameter were fabricated. This method is adaptable to any material that can be vapor-deposited, including indium-tin oxide (ITO), a conductive, transparent material that is useful for many opto-electronic applications. An array of gold nanotubes produced by this technique served as a substrate for surface-enhanced Raman spectroscopy: the Raman signal (per molecule) from a monolayer of benzenethiolate was a factor of approximately 5 x 10(5) greater than that obtained using bulk liquid benzenethiol.

  17. Effects of ion insertion on cycling performance of miniaturized electrochemical capacitor of carbon nanotubes array.

    Science.gov (United States)

    Tsai, Dah-Shyang; Chang, Chuan-hua; Chiang, Wei-Wen; Lee, Kuei-Yi; Huang, Ying-Sheng

    2014-10-24

    Capacity degradation and ion insertion of a miniaturized electrochemical capacitor are studied using ionic liquid [EMI] [TFSI] as the electrolyte. This capacitor is featured with two comb-like electrodes of vertical carbon nanotubes, ∼70 μm in height and 20 μm in interelectrode gap. We quantify the levels of ion insertion damage with Raman spectroscopy after the electrode experiences 120 consecutive voltammetric cycles to various potential limits. Distinct structural damage emerges due to [EMI] when the negative potential reaches -1.7 V, and those due to [TFSI] arise when the positive potential reaches 1.7 V vs. RHE. Judging from the peak broadenings, [EMI] is more detrimental than [TFSI]. When the voltage window ΔU is set as less than or equal to 2.8 V, both electrode potentials are within the two intercalation limits, little or no decay is observed in 10(4) charge/discharge cycles. When ΔU is 3.4 V, the positive potential exceeds the upper limit, but the negative potential stays within the lower limit, the cell capacitance decreases moderately. When ΔU increases to 3.8 V, both electrodes suffer from damages because of exceeding the intercalation limits. And the cell capacitance decreases substantially, even leading to a premature failure.

  18. A practical dimensionless equation for the thermal conductivity of carbon nanotubes and CNT arrays

    Directory of Open Access Journals (Sweden)

    Qiang Chen

    2014-05-01

    Full Text Available Experimental results reported in the last decade on the thermal conductivity of carbon nanotubes (CNTs have shown a fairly divergent behavior. An underlying intrinsic consistency was believed to exist in spite of the divergence in the thermal conductivity data of various CNTs. A dimenisonless equation that describes the temperature dependence of thermal conductivity was derived by introducing reduced forms relative to a chosen reference point. This equation can serve as a practical approximation to characterize the conductivity of individual CNT with different structural parameters as well as bulk CNT arrays with different bundle configurations. Comparison of predictions by the equation and historical measurements showed good agreements within their uncertainties.

  19. Multifunctional Material Structures Based on Laser-Etched Carbon Nanotube Arrays

    Directory of Open Access Journals (Sweden)

    Aline Emplit

    2014-09-01

    Full Text Available High-power electronics in the transportation and aerospace sectors need size and weight reduction. Multifunctional and multistructured materials are currently being developed to couple electromagnetic (EM and thermal properties, i.e., shielding against electromagnetic impulsions, and thermal management across the thermal interface material (TIM. In this work, we investigate laser-machined patterned carbon nanotube (CNT micro-brushes as an alternative to metallic structures for driving simultaneously EM and heat propagation. The thermal and electromagnetic response of the CNT array is expected to be sensitive to the micro-structured pattern etched in the CNT brush.

  20. Flexible symmetric supercapacitors based on vertical TiO2 and carbon nanotubes

    Science.gov (United States)

    Chien, C. J.; Chang, Pai-Chun; Lu, Jia G.

    2010-03-01

    Highly conducting and porous carbon nanotubes are widely used as electrodes in double-layer-effect supercapacitors. In this presentation, vertical TiO2 nanotube array is fabricated by anodization process and used as supercapacitor electrode utilizing its compact density, high surface area and porous structure. By spin coating carbon nanotube networks on vertical TiO2 nanotube array as electrodes with 1M H2SO4 electrolyte in between, the specific capacitance can be enhanced by 30% compared to using pure carbon nanotube network alone because of the combination of double layer effect and redox reaction from metal oxide materials. Based on cyclic voltammetry and galvanostatic charge-discharge measurements, this type of hybrid electrode has proven to be suitable for high performance supercapacitor application and maintain desirable cycling stability. The electrochemical impedance spectroscopy technique shows that the electrode has good electrical conductivity. Furthermore, we will discuss the prospect of extending this energy storage approach in flexible electronics.

  1. Application of carbon nanotubes-ionic liquid hybrid in a sensitive atorvastatin ion-selective electrode

    International Nuclear Information System (INIS)

    Jalali, Fahimeh; Ardeshiri, Moslem

    2016-01-01

    Atorvastatin (ATR) was determined by a potentiometric method. The ion-pair of ATR and cetyltrimethylammonium bromide (CTAB) was used as a suitable ionophore. A graphite paste electrode was modified with ATR-CTAB ion-pair, multiwalled carbon nanotubes (MWCNTs), and an ionic liquid, 1-butyl-3-mtehyl-imidazolium hexafluorophosphate (BMIMPF 6 ). The amounts of electrode ingredients were optimized (graphite powder: paraffin oil: ATR-CTAB: MWCNTs: BMIMPF 6 (58:26:5:8:3 w/w%). Surface characterization was done by using scanning electron microscopy. The potential measurements were recorded at optimized pH by using acetate buffer solution (0.1 mol L −1 , pH 5.5). At the above experimental conditions, calibration curve (E vs. log [ATR]) was linear (R 2 = 0.9977) in the concentration range of 1.0 × 10 −9 –1.0 × 10 −3 mol L −1 (0.0012–1209 mg L −1 ) of ATR with a Nernstian slope of 58.14 ± 0.2 mV decade −1 , and detection limit of 1.0 × 10 −9 mol L −1 (0.0013 mg L −1 ). After each injection of ATR to the buffer solution, the potential was stabilized in a very short time (average response time ~ 6 s) at 25 °C. The modified graphite paste electrode had a long lifetime (> 4 months). Recovery of the spiked drug to blood serum samples (95.3–98.2%) revealed the reliability of electrode response to ATR. Blood serum samples from consumers were analyzed by the proposed method; the results were comparable with those from HPLC standard method. The potentiometric analysis of ATR tablets by the proposed electrode resulted in a relative error of 0.8% and 1.5% for 20 and 40 mg per tablets, respectively. Finally, the electrode was used in potentiometric titration of ATR (1.0 × 10 −3 mol L −1 ) by CTAB (1.0 × 10 −3 mol L −1 ). Excellent accuracy (≈ 100%) was obtained from the volume of the titrant at the endpoint. - Graphical abstract: Graphite paste was modified with atorvastatin-CTAB (ATR-CTAB), ionic liquid (BMIMPF 6 ) and multiwalled carbon

  2. Application of carbon nanotubes-ionic liquid hybrid in a sensitive atorvastatin ion-selective electrode

    Energy Technology Data Exchange (ETDEWEB)

    Jalali, Fahimeh, E-mail: fjalali@razi.ac.ir; Ardeshiri, Moslem

    2016-12-01

    Atorvastatin (ATR) was determined by a potentiometric method. The ion-pair of ATR and cetyltrimethylammonium bromide (CTAB) was used as a suitable ionophore. A graphite paste electrode was modified with ATR-CTAB ion-pair, multiwalled carbon nanotubes (MWCNTs), and an ionic liquid, 1-butyl-3-mtehyl-imidazolium hexafluorophosphate (BMIMPF{sub 6}). The amounts of electrode ingredients were optimized (graphite powder: paraffin oil: ATR-CTAB: MWCNTs: BMIMPF{sub 6} (58:26:5:8:3 w/w%). Surface characterization was done by using scanning electron microscopy. The potential measurements were recorded at optimized pH by using acetate buffer solution (0.1 mol L{sup −1}, pH 5.5). At the above experimental conditions, calibration curve (E vs. log [ATR]) was linear (R{sup 2} = 0.9977) in the concentration range of 1.0 × 10{sup −9}–1.0 × 10{sup −3} mol L{sup −1} (0.0012–1209 mg L{sup −1}) of ATR with a Nernstian slope of 58.14 ± 0.2 mV decade{sup −1}, and detection limit of 1.0 × 10{sup −9} mol L{sup −1} (0.0013 mg L{sup −1}). After each injection of ATR to the buffer solution, the potential was stabilized in a very short time (average response time ~ 6 s) at 25 °C. The modified graphite paste electrode had a long lifetime (> 4 months). Recovery of the spiked drug to blood serum samples (95.3–98.2%) revealed the reliability of electrode response to ATR. Blood serum samples from consumers were analyzed by the proposed method; the results were comparable with those from HPLC standard method. The potentiometric analysis of ATR tablets by the proposed electrode resulted in a relative error of 0.8% and 1.5% for 20 and 40 mg per tablets, respectively. Finally, the electrode was used in potentiometric titration of ATR (1.0 × 10{sup −3} mol L{sup −1}) by CTAB (1.0 × 10{sup −3} mol L{sup −1}). Excellent accuracy (≈ 100%) was obtained from the volume of the titrant at the endpoint. - Graphical abstract: Graphite paste was modified with atorvastatin

  3. Preparation of Fe-doped TiO{sub 2} nanotube arrays and their photocatalytic activities under visible light

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Ya-Fang; Huang, Sheng-You [Department of Physics, Wuhan University, Wuhan 430072 (China); Sang, Jian-Ping, E-mail: jpsang@acc-lab.whu.edu.cn [Department of Physics, Wuhan University, Wuhan 430072 (China); Department of Physics, Jianghan University, Wuhan 430056 (China); Zou, Xian-Wu [Department of Physics, Wuhan University, Wuhan 430072 (China)

    2010-02-15

    Fe-doped TiO{sub 2} nanotube arrays have been prepared by the template-based liquid phase deposition method. Their morphologies, structures and optical properties were investigated by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and UV-vis absorption spectroscopy. Their photocatalytic activities were evaluated by the degradation of methylene blue under visible light. The UV-vis absorption spectra of the Fe-doped TiO{sub 2} nanotube arrays showed a red shift and an enhancement of the absorption in the visible region compared to the undoped sample. The Fe-doped TiO{sub 2} nanotube arrays exhibited good photocatalytic activities under visible light irradiation, and the optimum dopant amount was found to be 5.9 at% in our experiments.

  4. Interaction of a two-dimensional electromagnetic breather with an electron inhomogeneity in an array of carbon nanotubes

    International Nuclear Information System (INIS)

    Zhukov, Alexander V.; Bouffanais, Roland; Fedorov, E. G.; Belonenko, Mikhail B.

    2014-01-01

    Propagation of ultrashort laser pulses through various nano-objects has recently became an attractive topic for both theoretical and experimental studies due to its promising perspectives in a variety of problems of modern nanoelectronics. Here, we study the propagation of extremely short two-dimensional bipolar electromagnetic pulses in a heterogeneous array of semiconductor carbon nanotubes. Heterogeneity is defined as a region of enhanced electron density. The electromagnetic field in an array of nanotubes is described by Maxwell's equations, reduced to a multidimensional wave equation. Our numerical analysis shows the possibility of stable propagation of an electromagnetic pulse in a heterogeneous array of nanotubes. Furthermore, we establish that, depending on its speed of propagation, the pulse can pass through the area of increased electron concentration or be reflected therefrom.

  5. Electrochemically conductive treatment of TiO2 nanotube arrays in AlCl3 aqueous solution for supercapacitors

    Science.gov (United States)

    Zhong, Wenjie; Sang, Shangbin; Liu, Yingying; Wu, Qiumei; Liu, Kaiyu; Liu, Hongtao

    2015-10-01

    Highly ordered TiO2 nanotube arrays (NTAs) with excellent stability and large specific surface area make them competitive using as supercapacitor materials. Improving the conductivity of TiO2 is of great concern for the construction of high-performance supercapacitors. In this work, we developed a novel approach to improve the performance of TiO2 materials, involving the fabrication of Al-doped TiO2 NTAs by a simple electrochemical cathodic polarization treatment in AlCl3 aqueous solution. The prepared Al-doped TiO2 NTAs exhibited excellent electrochemical performances, attributing to the remarkably improved electrical conductivity (i.e., from approx. 10 kΩ to 20 Ω). Further analysis showed that Al3+ ions rather than H+ protons doped into TiO2 lattice cause this high conductivity. A MnO2/Al-TiO2 composite was evaluated by cyclic voltammetry, and achieved the specific capacitance of 544 F g-1, and the Ragone plot of the sample showed a high power density but less reduction of energy density. These results indicate that the MnO2/Al-TiO2 NTAs sample could be served as a promising electrode material for high -performance supercapacitors.

  6. Fabrication of Flexible Microneedle Array Electrodes for Wearable Bio-Signal Recording.

    Science.gov (United States)

    Ren, Lei; Xu, Shujia; Gao, Jie; Lin, Zi; Chen, Zhipeng; Liu, Bin; Liang, Liang; Jiang, Lelun

    2018-04-13

    Laser-direct writing (LDW) and magneto-rheological drawing lithography (MRDL) have been proposed for the fabrication of a flexible microneedle array electrode (MAE) for wearable bio-signal monitoring. Conductive patterns were directly written onto the flexible polyethylene terephthalate (PET) substrate by LDW. The microneedle array was rapidly drawn and formed from the droplets of curable magnetorheological fluid with the assistance of an external magnetic field by MRDL. A flexible MAE can maintain a stable contact interface with curved human skin due to the flexibility of the PET substrate. Compared with Ag/AgCl electrodes and flexible dry electrodes (FDE), the electrode-skin interface impedance of flexible MAE was the minimum even after a 50-cycle bending test. Flexible MAE can record electromyography (EMG), electroencephalography (EEG) and static electrocardiography (ECG) signals with good fidelity. The main features of the dynamic ECG signal recorded by flexible MAE are the most distinguishable with the least moving artifacts. Flexible MAE is an attractive candidate electrode for wearable bio-signal monitoring.

  7. Improving Impedance of Implantable Microwire Multi-Electrode Arrays by Ultrasonic Electroplating of Durable Platinum Black

    Science.gov (United States)

    Desai, Sharanya Arcot; Rolston, John D.; Guo, Liang; Potter, Steve M.

    2010-01-01

    Implantable microelectrode arrays (MEAs) have been a boon for neural stimulation and recording experiments. Commercially available MEAs have high impedances, due to their low surface area and small tip diameters, which are suitable for recording single unit activity. Lowering the electrode impedance, but preserving the small diameter, would provide a number of advantages, including reduced stimulation voltages, reduced stimulation artifacts and improved signal-to-noise ratio. Impedance reductions can be achieved by electroplating the MEAs with platinum (Pt) black, which increases the surface area but has little effect on the physical extent of the electrodes. However, because of the low durability of Pt black plating, this method has not been popular for chronic use. Sonicoplating (i.e. electroplating under ultrasonic agitation) has been shown to improve the durability of Pt black on the base metals of macro-electrodes used for cyclic voltammetry. This method has not previously been characterized for MEAs used in chronic neural implants. We show here that sonicoplating can lower the impedances of microwire multi-electrode arrays (MMEA) by an order of magnitude or more (depending on the time and voltage of electroplating), with better durability compared to pulsed plating or traditional DC methods. We also show the improved stimulation and recording performance that can be achieved in an in vivo implantation study with the sonicoplated low-impedance MMEAs, compared to high-impedance unplated electrodes. PMID:20485478

  8. DNA impedance biosensor for detection of cancer, TP53 gene mutation, based on gold nanoparticles/aligned carbon nanotubes modified electrode.

    Science.gov (United States)

    Fayazfar, H; Afshar, A; Dolati, M; Dolati, A

    2014-07-11

    For the first time, a new platform based on electrochemical growth of Au nanoparticles on aligned multi-walled carbon nanotubes (A-MWCNT) was developed for sensitive lable-free DNA detection of the TP53 gene mutation, one of the most popular genes in cancer research. Electrochemical impedance spectroscopy (EIS) was used to monitor the sequence-specific DNA hybridization events related to TP53 gene. Compared to the bare Ta or MWCNT/Ta electrodes, the synergistic interactions of vertically aligned MWCNT array and gold nanoparticles at modified electrode could improve the density of the probe DNA attachment and resulting the sensitivity of the DNA sensor greatly. Using EIS, over the extended DNA concentration range, the change of charge transfer resistance was found to have a linear relationship in respect to the logarithm of the complementary oligonucleotides sequence concentrations in the wide range of 1.0×10(-15)-1.0×10(-7)M, with a detection limit of 1.0×10(-17)M (S/N=3). The prepared sensor also showed good stability (14 days), reproducibility (RSD=2.1%) and could be conveniently regenerated via dehybridization in hot water. The significant improvement in sensitivity illustrates that combining gold nanoparticles with the on-site fabricated aligned MWCNT array represents a promising platform for achieving sensitive biosensor for fast mutation screening related to most human cancer types. Copyright © 2014. Published by Elsevier B.V.

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

    International Nuclear Information System (INIS)

    Beitollahi, Hadi; Sheikhshoaie, Iran

    2011-01-01

    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 μM, 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.

  10. Carbon nanotube ensembled hybrid nanocomposite electrode for direct electrochemical detection of epinephrine in pharmaceutical tablets and urine.

    Science.gov (United States)

    Koteshwara Reddy, K; Satyanarayana, M; Yugender Goud, K; Vengatajalabathy Gobi, K; Kim, Hern

    2017-10-01

    An efficient electrochemical sensor for selective detection of the neurotransmitter, epinephrine (Epn), has been fabricated with the aid of a functionalized multiwall carbon nanotube-chitosan biopolymer nanocomposite (Chit-fCNT) electrode. Multiwall carbon nanotubes (CNT) were successfully functionalized with the aid of nitric acid and confirmed by the Raman spectral data. Functionalized carbon nanotubes (fCNT) were dispersed in chitosan solution and the resulting bio-nanocomposite was used for the fabrication of sensor surface by drop and cast method. Electrochemical characteristics of the fabricated sensor were understood using cyclic, differential pulse voltammetry (CV, DPV) and electrochemical impedance analysis for the detection of Epn in phosphate buffer (pH7.4). CV and impedance analysis revealed that the Chit-fCNT modified electrode enhances the electrodic reaction of Epn and facilitated the electron transfer more readily compared to that of bare electrode. Applying DPV for the detection of Epn, achieved 30nM as the lowest detection limit in the determination range of 0.05-10μM and the analytical time as low as 10s. Selective determination of Epn against the coexistence of a number of biological electroactive interferents and reproducible results for the determination of Epn were demonstrated. The present biosensor has been found efficient for successful direct determination of Epn from pharmaceutical adrenaline formulations and urine samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Preparation of Janus Particles and Alternating Current Electrokinetic Measurements with a Rapidly Fabricated Indium Tin Oxide Electrode Array.

    Science.gov (United States)

    Chen, Yu-Liang; Jiang, Hong-Ren

    2017-06-23

    This article provides a simple method to prepare partially or fully coated metallic particles and to perform the rapid fabrication of electrode arrays, which can facilitate electrical experiments in microfluidic devices. Janus particles are asymmetric particles that contain two different surface properties on their two sides. To prepare Janus particles, a monolayer of silica particles is prepared by a drying process. Gold (Au) is deposited on one side of each particle using a sputtering device. The fully coated metallic particles are completed after the second coating process. To analyze the electrical surface properties of Janus particles, alternating current (AC) electrokinetic measurements, such as dielectrophoresis (DEP) and electrorotation (EROT)- which require specifically designed electrode arrays in the experimental device- are performed. However, traditional methods to fabricate electrode arrays, such as the photolithographic technique, require a series of complicated procedures. Here, we introduce a flexible method to fabricate a designed electrode array. An indium tin oxide (ITO) glass is patterned by a fiber laser marking machine (1,064 nm, 20 W, 90 to 120 ns pulse-width, and 20 to 80 kHz pulse repetition frequency) to create a four-phase electrode array. To generate the four-phase electric field, the electrodes are connected to a 2-channel function generator and to two invertors. The phase shift between the adjacent electrodes is set at either 90° (for EROT) or 180° (for DEP). Representative results of AC electrokinetic measurements with a four-phase ITO electrode array are presented.

  12. Design of lithium cobalt oxide electrodes with high thermal conductivity and electrochemical performance using carbon nanotubes and diamond particles

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eungje; Salgado, Ruben Arash; Lee, Byeongdu; Sumant, Anirudha V.; Rajh, Tijana; Johnson, Christopher; Balandin, Alexander A.; Shevchenko, Elena V.

    2018-04-01

    Thermal management remains one of the major challenges in the design of safe and reliable Li-ion batteries. We show that composite electrodes assembled from commercially available 100 μm long carbon nanotubes (CNTs) and LiCoO2 (LCO) particles demonstrate the in-plane thermal conductivity of 205.8 W/m*K. This value exceeds the thermal conductivity of dry conventional laminated electrodes by about three orders of magnitude. The cross-plane thermal conductivity of CNT-based electrodes is in the same range as thermal conductivities of conventional laminated electrodes. The CNT-based electrodes demonstrate a similar capacity to conventional laminated design electrodes, but revealed a better rate performance and stability. The introduction of diamond particles into CNT-based electrodes further improves the rate performance. Our lightweight, flexible electrode design can potentially be a general platform for fabricating polymer binder- and aluminum and copper current collector- free electrodes from a broad range of electrochemically active materials with efficient thermal management.

  13. Conformal atomic layer deposition of alumina on millimeter tall, vertically-aligned carbon nanotube arrays.

    Science.gov (United States)

    Stano, Kelly L; Carroll, Murphy; Padbury, Richard; McCord, Marian; Jur, Jesse S; Bradford, Philip D

    2014-11-12

    Atomic layer deposition (ALD) can be used to coat high aspect ratio and high surface area substrates with conformal and precisely controlled thin films. Vertically aligned arrays of multiwalled carbon nanotubes (MWCNTs) with lengths up to 1.5 mm were conformally coated with alumina from base to tip. The nucleation and growth behaviors of Al2O3 ALD precursors on the MWCNTs were studied as a function of CNT surface chemistry. CNT surfaces were modified through a series of post-treatments including pyrolytic carbon deposition, high temperature thermal annealing, and oxygen plasma functionalization. Conformal coatings were achieved where post-treatments resulted in increased defect density as well as the extent of functionalization, as characterized by X-ray photoelectron spectroscopy and Raman spectroscopy. Using thermogravimetric analysis, it was determined that MWCNTs treated with pyrolytic carbon and plasma functionalization prior to ALD coating were more stable to thermal oxidation than pristine ALD coated samples. Functionalized and ALD coated arrays had a compressive modulus more than two times higher than a pristine array coated for the same number of cycles. Cross-sectional energy dispersive X-ray spectroscopy confirmed that Al2O3 could be uniformly deposited through the entire thickness of the vertically aligned MWCNT array by manipulating sample orientation and mounting techniques. Following the ALD coating, the MWCNT arrays demonstrated hydrophilic wetting behavior and also exhibited foam-like recovery following compressive strain.

  14. Improved electrochemical performance of polyindole/carbon nanotubes composite as electrode material for supercapacitors

    Science.gov (United States)

    Cai, Zhi-Jiang; Zhang, Qin; Song, Xian-You

    2016-09-01

    Polyindole/carbon nanotubes (PIN/CNTs) composite was prepared by an in-situ chemical oxidative polymerization of indole monomer with CNTs using ammonium persulfate as oxidant. The obtained composite material was characterized by SEM, TEM, FT-IR, Raman spectroscopy, XPS, XRD and BET surface areas measurements. It was found that the CNTs were incorporated into the PIN matrix and nanoporous structure was formed. Spectroscopy results showed that interfacial interaction bonds might be formed between the polyindole chains and CNTs during the in-situ polymerization. PIN/CNTs composite was evaluated by electrochemical impedance spectroscopy, cyclic voltammetry and charge/discharge tests to determine electrode performances in relation to supercapacitors properties in both aqueous and non-aqueous system. A maximum specific capacitance and specific volumetric capacitance of 555.6 F/g and 222.2 F/cm3 can be achieved at 0.5 A/g in non-aqueous system. It also displayed good rate performance and cycling stability. The specific capacitance retention is over 60% at 10 A/g and 91.3% after 5000 cycles at 2 A/g, respectively. These characteristics point to its promising applications in the electrode material for supercapacitors.

  15. 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. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Enhanced luminol electrochemiluminescence triggered by an electrode functionalized with dendrimers modified with titanate nanotubes

    International Nuclear Information System (INIS)

    Lin, Yanyu; Yang, Yusheng; Dai, Hong; Xu, Guifang; Yang, Ting; Tong, Yuejin; Yang, Caiping; Chen, Guonan

    2013-01-01

    We have constructed a novel electro chemiluminescence (ECL) platform by functionalizing a poly(amidoamine) dendrimer (PAAD) with titanate nanotubes (TiNTs). The PAAD has an open spherical structure that possesses a high density of active groups and thus favors mass transport, while the TiNTs possess excellent electronic conductivity and thus can promote electron transfer on the surface of a glassy carbon electrode (GCE). A study on the intensity and stability of the ECL of luminol on the modified GCE revealed a substantial improvement compared to that of a bare GCE. The effects of the concentration of TiNTs, the pH value of the solution, and of electrochemical parameters on the intensity of the ECL of luminol were studied and resulted in a sensitive ECL sensor for hydrogen peroxide (H 2 O 2 ) that works in the concentration range of 1 nM to 0.9 μM. The scavenging effect of superoxide dismutase (SOD) on the H 2 O 2 electrode ECL was then exploited to design a biosensor for the determination of SOD in concentrations between 50 and 500 nM. (author)

  17. Electrochemical Oxidation of Sulfamethazine on Multi-Walled Nanotube Film Coated Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    L. Fotouhi

    2014-04-01

    Full Text Available The electrochemical oxidation of sulfamethazine (SMZ has been studied at a multi-walled carbon nanotubes modified glassy carbon electrode (MWCNT-GCE by cyclic voltammetry. This modified electrode (MWCNT-GCE exhibited excellent electrocatalytic behavior toward the oxidation of SMZ as evidenced by the enhancement of the oxidation peak current and the shift in the anodic potential to less positive values (170 mV in comparison with the bare GCE. The formal potential, E0', of SMZ is pH dependent with a slope of 54 mV per unit of pH, close to the anticipated Nerstian value of 59 mV for a 2-electron and 2-proton oxidation process. A detailed analysis of cyclic voltammograms gave fundamental electrochemical parameters including the electroactive surface coverage (Г, the transfer coefficient (a, the heterogeneous rate constant (ks. Under the selected conditions, the peak current shows two dynamic linear ranges of 10-200 mM and 300-3000 mM with the detection limit of 6.1 mM. The method was successfully applied to analyze SMZ in serum sample

  18. 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.

  19. Action potential propagation recorded from single axonal arbors using multi-electrode arrays.

    Science.gov (United States)

    Tovar, Kenneth R; Bridges, Daniel C; Wu, Bian; Randall, Connor; Audouard, Morgane; Jang, Jiwon; Hansma, Paul K; Kosik, Kenneth S

    2018-04-11

    We report the presence of co-occurring extracellular action potentials (eAPs) from cultured mouse hippocampal neurons among groups of planar electrodes on multi-electrode arrays (MEAs). The invariant sequences of eAPs among co-active electrode groups, repeated co-occurrences and short inter-electrode latencies are consistent with action potential propagation in unmyelinated axons. Repeated eAP co-detection by multiple electrodes was widespread in all our data records. Co-detection of eAPs confirms they result from the same neuron and allows these eAPs to be isolated from all other spikes independently of spike sorting algorithms. We averaged co-occurring events and revealed additional electrodes with eAPs that would otherwise be below detection threshold. We used these eAP cohorts to explore the temperature sensitivity of action potential propagation and the relationship between voltage-gated sodium channel density and propagation velocity. The sequence of eAPs among co-active electrodes 'fingerprints' neurons giving rise to these events and identifies them within neuronal ensembles. We used this property and the non-invasive nature of extracellular recording to monitor changes in excitability at multiple points in single axonal arbors simultaneously over several hours, demonstrating independence of axonal segments. Over several weeks, we recorded changes in inter-electrode propagation latencies and ongoing changes in excitability in different regions of single axonal arbors. Our work illustrates how repeated eAP co-occurrences can be used to extract physiological data from single axons with low electrode density MEAs. However, repeated eAP co-occurrences leads to over-sampling spikes from single neurons and thus can confound traditional spike-train analysis.

  20. Fabrication and photoelectrochemical properties of ZnS/Au/TiO2 nanotube array films.

    Science.gov (United States)

    Zhu, Yan-Feng; Zhang, Juan; Xu, Lu; Guo, Ya; Wang, Xiao-Ping; Du, Rong-Gui; Lin, Chang-Jian

    2013-03-21

    A highly ordered TiO(2) nanotube array film was fabricated by an anodic oxidation method. The film was modified by Au nanoparticles (NPs) formed by a deposition-precipitation technique and was covered with a thin ZnS shell prepared by a successive ionic layer adsorption and reaction (SILAR) method. The photoelectrochemical properties of the prepared ZnS/Au/TiO(2) composite film were evaluated by incident photon-to-current conversion efficiency (IPCE), and photopotential and electrochemical impedance spectroscopy (EIS) measurements under white light illumination. The results indicated that the Au NPs could expand the light sensitivity range of the film and suppress the electron-hole recombination, and the ZnS shell could inhibit the leakage of photogenerated electrons from the surface of Au NPs to the ZnS/electrolyte interface. When the 403 stainless steel in a 0.5 M NaCl solution was coupled to the ZnS/Au/TiO(2) nanotube film photoanode under illumination, its potential decreased by 400 mV, showing that the composite film had a better photocathodic protection effect on the steel than that of a pure TiO(2) nanotube film.

  1. Room temperature alcohol sensing by oxygen vacancy controlled TiO{sub 2} nanotube array

    Energy Technology Data Exchange (ETDEWEB)

    Hazra, A.; Dutta, K.; Bhowmik, B.; Bhattacharyya, P., E-mail: pb-etc-besu@yahoo.com [Nano-Thin Films and Solid State Gas Sensor Devices Laboratory, Department of Electronics and Telecommunication Engineering, Indian Institute of Engineering Science and Technology (IIEST), Shibpur, Howrah (India); Chattopadhyay, P. P. [Department of Metallurgy and Materials Engineering, Indian Institute of Engineering Science and Technology (IIEST), Shibpur, Howrah (India)

    2014-08-25

    Oxygen vacancy (OV) controlled TiO{sub 2} nanotubes, having diameters of 50–70 nm and lengths of 200–250 nm, were synthesized by electrochemical anodization in the mixed electrolyte comprising NH{sub 4}F and ethylene glycol with selective H{sub 2}O content. The structural evolution of TiO{sub 2} nanoforms has been studied by field emission scanning electron microscopy. Variation in the formation of OVs with the variation of the structure of TiO{sub 2} nanoforms has been evaluated by photoluminescence and X-ray photoelectron spectroscopy. The sensor characteristics were correlated to the variation of the amount of induced OVs in the nanotubes. The efficient room temperature sensing achieved by the control of OVs of TiO{sub 2} nanotube array has paved the way for developing fast responding alcohol sensor with corresponding response magnitude of 60.2%, 45.3%, and 36.5% towards methanol, ethanol, and 2-propanol, respectively.

  2. Morphological evolution of TiO2 nanotube arrays with lotus-root-shaped nanostructure

    Science.gov (United States)

    Yu, Dongliang; Song, Ye; Zhu, Xufei; Yang, Ruiquan; Han, Aijun

    2013-07-01

    TiO2 nanotube arrays (TNAs) with lotus-root-shaped nanostructure have been fabricated by a modified two-step electrochemical anodization method. In the present work, different morphologies formed under different anodizing voltages are investigated in detail by field-emission scanning electron microscope. The results show that the concaves left by the first-step anodization can guide the uniform growth of TNAs in some degree as the second-step anodizing voltage is the same with that in the first step, however, when lower voltages are adopted in the second-step anodization, no guidance can be achieved, and different morphological TNAs with lotus-root-shaped nanostructure are fabricated. And we find that the nanotube diameters are directly proportional to the applied voltage in the second-step anodization. Furthermore, a possible mechanism for the growth of the TiO2 nanotubes with the special morphology is proposed for the first time, which depends on both the oxygen bubble mold and the viscous flow of the barrier oxide from the pore base to the pore wall.

  3. Morphological evolution of TiO{sub 2} nanotube arrays with lotus-root-shaped nanostructure

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Dongliang; Song, Ye; Zhu, Xufei, E-mail: zhuxufei.njust@163.com; Yang, Ruiquan; Han, Aijun

    2013-07-01

    TiO{sub 2} nanotube arrays (TNAs) with lotus-root-shaped nanostructure have been fabricated by a modified two-step electrochemical anodization method. In the present work, different morphologies formed under different anodizing voltages are investigated in detail by field-emission scanning electron microscope. The results show that the concaves left by the first-step anodization can guide the uniform growth of TNAs in some degree as the second-step anodizing voltage is the same with that in the first step, however, when lower voltages are adopted in the second-step anodization, no guidance can be achieved, and different morphological TNAs with lotus-root-shaped nanostructure are fabricated. And we find that the nanotube diameters are directly proportional to the applied voltage in the second-step anodization. Furthermore, a possible mechanism for the growth of the TiO{sub 2} nanotubes with the special morphology is proposed for the first time, which depends on both the oxygen bubble mold and the viscous flow of the barrier oxide from the pore base to the pore wall.

  4. Investigation of a new electrode array technology for a central auditory prosthesis.

    Directory of Open Access Journals (Sweden)

    Roger Calixto

    Full Text Available Ongoing clinical studies on patients recently implanted with the auditory midbrain implant (AMI into the inferior colliculus (IC for hearing restoration have shown that these patients do not achieve performance levels comparable to cochlear implant patients. The AMI consists of a single-shank array (20 electrodes for stimulation along the tonotopic axis of the IC. Recent findings suggest that one major limitation in AMI performance is the inability to sufficiently activate neurons across the three-dimensional (3-D IC. Unfortunately, there are no currently available 3-D array technologies that can be used for clinical applications. More recently, there has been a new initiative by the European Commission to fund and develop 3-D chronic electrode arrays for science and clinical applications through the NeuroProbes project that can overcome the bulkiness and limited 3-D configurations of currently available array technologies. As part of the NeuroProbes initiative, we investigated whether their new array technology could be potentially used for future AMI patients. Since the NeuroProbes technology had not yet been tested for electrical stimulation in an in vivo animal preparation, we performed experiments in ketamine-anesthetized guinea pigs in which we inserted and stimulated a NeuroProbes array within the IC and recorded the corresponding neural activation within the auditory cortex. We used 2-D arrays for this initial feasibility study since they were already available and were sufficient to access the IC and also demonstrate effective activation of the central auditory system. Based on these encouraging results and the ability to develop customized 3-D arrays with the NeuroProbes technology, we can further investigate different stimulation patterns across the ICC to improve AMI performance.

  5. Effects of interfaces on nano-friction of vertically aligned multi-walled carbon nanotube arrays

    International Nuclear Information System (INIS)

    Lou, J.; Kim, K.-S.

    2008-01-01

    Sliding friction properties of vertically aligned multi-walled carbon nanotube (VAMWNT) arrays have been investigated in current study in a quantitative manner. The VAMWNT arrays have been fabricated on an anodic aluminum oxide template by chemical vapor deposition at 650 deg. C. Friction force was measured in air by a modified atomic force microscopy (AFM) cantilever-bead assembly with 15 μm diameter borosilicate sphere attached to the end of the regular AFM cantilever. Quantitative measurements were achieved by using a novel in situ calibration methods recently developed based on diamagnetic levitation [Q. Li, K.-S. Kim, A. Rydberg, Rev. Sci. Instrum. 77 (2006) 065105-1-13]. The effects of different interfaces were studied using both cantilever-bead assembly coated with and without Al thin layer coatings. A reverse stick-slip behavior was observed in the current system as compared to the normal stick-slip behavior found in the literature

  6. Wafer-Level Patterned and Aligned Polymer Nanowire/Micro- and Nanotube Arrays on any Substrate

    KAUST Repository

    Morber, Jenny Ruth

    2009-05-25

    A study was conducted to fabricate wafer-level patterned and aligned polymer nanowire (PNW), micro- and nanotube arrays (PNT), which were created by exposing the polymer material to plasma etching. The approach for producing wafer-level aligned PNWs involved a one-step inductively coupled plasma (ICP) reactive ion etching process. The polymer nanowire array was fabricated in an ICP reactive ion milling chamber with a pressure of 10mTorr. Argon (Ar), O 2, and CF4 gases were released into the chamber as etchants at flow rates of 15 sccm, 10 sccm, and 40 sccm. Inert gasses, such as Ar-form positive ions were incorporated to serve as a physical component to assist in the material degradation process. One power source (400 W) was used to generate dense plasma from the input gases, while another power source applied a voltage of approximately 600V to accelerate the plasma toward the substrate.

  7. Femtosecond laser modification of an array of vertically aligned carbon nanotubes intercalated with Fe phase nanoparticles.

    Science.gov (United States)

    Labunov, Vladimir; Prudnikava, Alena; Bushuk, Serguei; Filatov, Serguei; Shulitski, Boris; Tay, Beng Kang; Shaman, Yury; Basaev, Alexander

    2013-09-03

    Femtosecond lasers (FSL) are playing an increasingly important role in materials research, characterization, and modification. Due to an extremely short pulse width, interactions of FSL irradiation with solid surfaces attract special interest, and a number of unusual phenomena resulted in the formation of new materials are expected. Here, we report on a new nanostructure observed after the interaction of FSL irradiation with arrays of vertically aligned carbon nanotubes (CNTs) intercalated with iron phase catalyst nanoparticles. It was revealed that the FSL laser ablation transforms the topmost layer of CNT array into iron phase nanospheres (40 to 680 nm in diameter) located at the tip of the CNT bundles of conical shape. Besides, the smaller nanospheres (10 to 30 nm in diameter) are found to be beaded at the sides of these bundles. Some of the larger nanospheres are encapsulated into carbon shells, which sometime are found to contain CNTs. The mechanism of creation of such nanostructures is proposed.

  8. Controllable 3D architectures of aligned carbon nanotube arrays by multi-step processes

    Science.gov (United States)

    Huang, Shaoming

    2003-06-01

    An effective way to fabricate large area three-dimensional (3D) aligned CNTs pattern based on pyrolysis of iron(II) phthalocyanine (FePc) by two-step processes is reported. The controllable generation of different lengths and selective growth of the aligned CNT arrays on metal-patterned (e.g., Ag and Au) substrate are the bases for generating such 3D aligned CNTs architectures. By controlling experimental conditions 3D aligned CNT arrays with different lengths/densities and morphologies/structures as well as multi-layered architectures can be fabricated in large scale by multi-step pyrolysis of FePc. These 3D architectures could have interesting properties and be applied for developing novel nanotube-based devices.

  9. Dysprosium-Catalyzed Growth of Single-Walled Carbon Nanotube Arrays on Substrates

    Directory of Open Access Journals (Sweden)

    Qian Yong

    2009-01-01

    Full Text Available Abstract In this letter, we report that dysprosium is an effective catalyst for single-walled carbon nanotubes (SWNTs growth via a chemical vapor deposition (CVD process for the first time. Horizontally superlong well-oriented SWNT arrays on SiO2/Si wafer can be fabricated by EtOH-CVD under suitable conditions. The structure and properties are characterized by scanning electron microscopy, transition electron microscopy, Raman spectroscopy and atomic force microscopy. The results show that the SWNTs from dysprosium have better structural uniformity and better conductivity with fewer defects. This rare earth metal provides not only an alternative catalyst for SWNTs growth, but also a possible method to generate high percentage of superlong semiconducting SWNT arrays for various applications of nanoelectronic device.

  10. Synthesis and Investigation of Millimeter-Scale Vertically Aligned Boron Nitride Nanotube Arrays

    Science.gov (United States)

    Tay, Roland; Li, Hongling; Tsang, Siu Hon; Jing, Lin; Tan, Dunlin; Teo, Edwin Hang Tong

    Boron nitride nanotubes (BNNTs) have shown potential in a wide range of applications due to their superior properties such as exceptionally high mechanical strength, excellent chemical and thermal stabilities. However, previously reported methods to date only produced BNNTs with limited length/density and insufficient yield at high temperatures. Here we present a facile and effective two-step synthesis route involving template-assisted chemical vapor deposition at a relatively low temperature of 900 degree C and subsequent annealing process to fabricate vertically aligned (VA) BN coated carbon nanotube (VA-BN/CNT) and VA-BNNT arrays. By using this method, we achieve the longest VA-BN/CNTs and VA-BNNTs to date with lengths of over millimeters (exceeding two orders of magnitude longer than the previously reported length of VA-BNNTs). In addition, the morphology, chemical composition and microstructure of the resulting products, as well as the mechanism of coating process are systematically investigated. This versatile BN coating technique and the synthesis of millimeter-scale BN/CNT and BNNT arrays pave a way for new applications especially where the aligned geometry of the NTs is essential such as for field-emission, interconnects and thermal management.

  11. Aligned Carbon Nanotube Arrays Bonded to Solid Graphite Substrates: Thermal Analysis for Future Device Cooling Applications

    Directory of Open Access Journals (Sweden)

    Betty T. Quinton

    2018-05-01

    Full Text Available Carbon nanotubes (CNTs are known for high thermal conductivity and have potential use as nano-radiators or heat exchangers. This paper focuses on the thermal performance of carpet-like arrays of vertically aligned CNTs on solid graphite substrates with the idea of investigating their behavior as a function of carpet dimensions and predicting their performance as thermal interface material (TIM for electronic device cooling. Vertically aligned CNTs were grown on highly oriented pyrolytic graphite (HOPG substrate, which creates a robust and durable all-carbon hierarchical structure. The multi-layer thermal analysis approach using Netzsch laser flash analysis system was used to evaluate their performance as a function of carpet height, from which their thermal properties can be determined. It was seen that the thermal resistance of the CNT array varies linearly with CNT carpet height, providing a unique way of decoupling the properties of the CNT carpet from its interface. This data was used to estimate the thermal conductivity of individual multi-walled nanotube strands in this carpet, which was about 35 W/m-K. The influence of CNT carpet parameters (aerial density, diameter, and length on thermal resistance of the CNT carpet and its potential advantages and limitations as an integrated TIM are discussed.

  12. Low-cost silver capped polystyrene nanotube arrays as super-hydrophobic substrates for SERS applications.

    Science.gov (United States)

    Lovera, Pierre; Creedon, Niamh; Alatawi, Hanan; Mitchell, Micki; Burke, Micheal; Quinn, Aidan J; O'Riordan, Alan

    2014-05-02

    In this paper, we describe the fabrication, simulation and characterization of dense arrays of freestanding silver capped polystyrene nanotubes, and demonstrate their suitability for surface enhanced Raman scattering (SERS) applications. Substrates are fabricated in a rapid, low-cost and scalable way by melt wetting of polystyrene (PS) in an anodized alumina (AAO) template, followed by silver evaporation. Scanning electron microscopy reveals that substrates are composed of a dense array of freestanding polystyrene nanotubes topped by silver nanocaps. SERS characterization of the substrates, employing a monolayer of 4-aminothiophenol (4-ABT) as a model molecule, exhibits an enhancement factor of ∼1.6 × 10(6), in agreement with 3D finite difference time domain simulations. Contact angle measurements of the substrates revealed super-hydrophobic properties, allowing pre-concentration of target analyte into a small volume. These super-hydrophobic properties of the samples are taken advantage of for sensitive detection of the organic pollutant crystal violet, with detection down to ∼400 ppt in a 2 μl aliquot demonstrated.

  13. Low-cost silver capped polystyrene nanotube arrays as super-hydrophobic substrates for SERS applications

    International Nuclear Information System (INIS)

    Lovera, Pierre; Creedon, Niamh; Alatawi, Hanan; Mitchell, Micki; Burke, Micheal; Quinn, Aidan J; O’Riordan, Alan

    2014-01-01

    In this paper, we describe the fabrication, simulation and characterization of dense arrays of freestanding silver capped polystyrene nanotubes, and demonstrate their suitability for surface enhanced Raman scattering (SERS) applications. Substrates are fabricated in a rapid, low-cost and scalable way by melt wetting of polystyrene (PS) in an anodized alumina (AAO) template, followed by silver evaporation. Scanning electron microscopy reveals that substrates are composed of a dense array of freestanding polystyrene nanotubes topped by silver nanocaps. SERS characterization of the substrates, employing a monolayer of 4-aminothiophenol (4-ABT) as a model molecule, exhibits an enhancement factor of ∼1.6 × 10 6 , in agreement with 3D finite difference time domain simulations. Contact angle measurements of the substrates revealed super-hydrophobic properties, allowing pre-concentration of target analyte into a small volume. These super-hydrophobic properties of the samples are taken advantage of for sensitive detection of the organic pollutant crystal violet, with detection down to ∼400 ppt in a 2 μl aliquot demonstrated. (paper)

  14. Dye-Sensitized Solar Cells Based on TiO_2 Nanotube and Shelled Arrayed Structures

    International Nuclear Information System (INIS)

    Zhang, Jie; Kusumawati, Yuly; Pauporté, Thierry

    2016-01-01

    Anatase TiO_2 nanostructure arrays were synthetized starting from a template made of self-standing ZnO NWs prepared by an electrodeposition technique. By controlling the liquid phase deposition step, the obtained structures could be varied from free-standing nanotube (NT) arrays with controlled morphology to hierarchical spiky radiating core-shell rods. The nanotubes were made of assembled nanocrystals with an average size of 7–8 nm. The structures were investigated as n-type layers in DSSCs. The efficiency was enhanced for the core-shell layer and by starting with longer initial ZnO NW templates. The limitation of the cell efficiency was shown related to the specific surface area and dye loading. The cell functioning was in-depth investigated by electrochemical impedance spectroscopy over a large applied voltage range and compared to a cell based on a nanoparticle TO_2 mesoporous layer. A slow recombination rate was found. The enhancement of electron transport with nanocrystallite size explained the conductivity results. We also found that the prepared structures presented a high charge collection efficiency.

  15. Drug-eluting Ti wires with titania nanotube arrays for bone fixation and reduced bone infection

    Science.gov (United States)

    Gulati, Karan; Aw, Moom Sinn; Losic, Dusan

    2011-10-01

    Current bone fixation technology which uses stainless steel wires known as Kirschner wires for fracture fixing often causes infection and reduced skeletal load resulting in implant failure. Creating new wires with drug-eluting properties to locally deliver drugs is an appealing approach to address some of these problems. This study presents the use of titanium [Ti] wires with titania nanotube [TNT] arrays formed with a drug delivery capability to design alternative bone fixation tools for orthopaedic applications. A titania layer with an array of nanotube structures was synthesised on the surface of a Ti wire by electrochemical anodisation and loaded with antibiotic (gentamicin) used as a model of bone anti-bacterial drug. Successful fabrication of TNT structures with pore diameters of approximately 170 nm and length of 70 μm is demonstrated for the first time in the form of wires. The drug release characteristics of TNT-Ti wires were evaluated, showing a two-phase release, with a burst release (37%) and a slow release with zero-order kinetics over 11 days. These results confirmed our system's ability to be applied as a drug-eluting tool for orthopaedic applications. The established biocompatibility of TNT structures, closer modulus of elasticity to natural bones and possible inclusion of desired drugs, proteins or growth factors make this system a promising alternative to replace conventional bone implants to prevent bone infection and to be used for targeted treatment of bone cancer, osteomyelitis and other orthopaedic diseases.

  16. Optimization of focality and direction in dense electrode array transcranial direct current stimulation (tDCS)

    Science.gov (United States)

    Guler, Seyhmus; Dannhauer, Moritz; Erem, Burak; Macleod, Rob; Tucker, Don; Turovets, Sergei; Luu, Phan; Erdogmus, Deniz; Brooks, Dana H.

    2016-06-01

    Objective. Transcranial direct current stimulation (tDCS) aims to alter brain function non-invasively via electrodes placed on the scalp. Conventional tDCS uses two relatively large patch electrodes to deliver electrical current to the brain region of interest (ROI). Recent studies have shown that using dense arrays containing up to 512 smaller electrodes may increase the precision of targeting ROIs. However, this creates a need for methods to determine effective and safe stimulus patterns as the number of degrees of freedom is much higher with such arrays. Several approaches to this problem have appeared in the literature. In this paper, we describe a new method for calculating optimal electrode stimulus patterns for targeted and directional modulation in dense array tDCS which differs in some important aspects with methods reported to date. Approach. We optimize stimulus pattern of dense arrays with fixed electrode placement to maximize the current density in a particular direction in the ROI. We impose a flexible set of safety constraints on the current power in the brain, individual electrode currents, and total injected current, to protect subject safety. The proposed optimization problem is convex and thus efficiently solved using existing optimization software to find unique and globally optimal electrode stimulus patterns. Main results. Solutions for four anatomical ROIs based on a realistic head model are shown as exemplary results. To illustrate the differences between our approach and previously introduced methods, we compare our method with two of the other leading methods in the literature. We also report on extensive simulations that show the effect of the values chosen for each proposed safety constraint bound on the optimized stimulus patterns. Significance. The proposed optimization approach employs volume based ROIs, easily adapts to different sets of safety constraints, and takes negligible time to compute. An in-depth comparison study gives

  17. 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)

    Poorahong, S.; Thammakhet, C.; Numnuam, A.; Kanatharana, P.; Thavarungkul, P.; Limbut, W.

    2012-01-01

    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)

  18. Bipolar Electrode Array Embedded in a Polymer Light-Emitting Electrochemical Cell.

    Science.gov (United States)

    Gao, Jun; Chen, Shulun; AlTal, Faleh; Hu, Shiyu; Bouffier, Laurent; Wantz, Guillaume

    2017-09-20

    A linear array of aluminum discs is deposited between the driving electrodes of an extremely large planar polymer light-emitting electrochemical cell (PLEC). The planar PLEC is then operated at a constant bias voltage of 100 V. This promotes in situ electrochemical doping of the luminescent polymer from both the driving electrodes and the aluminum discs. These aluminum discs function as discrete bipolar electrodes (BPEs) that can drive redox reactions at their extremities. Time-lapse fluorescence imaging reveals that p- and n-doping that originated from neighboring BPEs can interact to form multiple light-emitting p-n junctions in series. This provides direct evidence of the working principle of bulk homojunction PLECs. The propagation of p-doping is faster from the BPEs than from the positive driving electrode due to electric field enhancement at the extremities of BPEs. The effect of field enhancement and the fact that the doping fronts only need to travel the distance between the neighboring BPEs to form a light-emitting junction greatly reduce the response time for electroluminescence in the region containing the BPE array. The near simultaneous formation of multiple light-emitting p-n junctions in series causes a measurable increase in cell current. This indicates that the region containing a BPE is much more conductive than the rest of the planar cell despite the latter's greater width. The p- and n-doping originating from the BPEs is initially highly confined. Significant expansion and divergence of doping occurred when the region containing the BPE array became more conductive. The shape and direction of expanded doping strongly suggest that the multiple light-emitting p-n junctions, formed between and connected by the array of metal BPEs, have functioned as a single rod-shaped BPE. This represents a new type of BPE that is formed in situ and as a combination of metal, doped polymers, and forward-biased p-n junctions connected in series.

  19. Determination of Patulin Using Amperometric Tyrosinase Biosensors Based on Electrodes Modified with Carbon Nanotubes and Gold Nanoparticles

    Directory of Open Access Journals (Sweden)

    R.M. Varlamova

    2016-06-01

    Full Text Available New amperometric biosensors based on platinum screen printed electrodes modified with multi-walled carbon nanotubes, gold nanoparticles, and immobilized enzyme – tyrosinase have been developed for determination of patulin in the concentrations of 1·10–6 – 8·10–12 mol/L with an error of no more than 0.063. The best conditions for obtaining gold nanoparticles have been chosen. The conditions for immobilization of multi-walled carbon nanotubes and gold nanoparticles on the surface of the planar electrode have been revealed. The conditions for functioning of the proposed biosensors have been identified. The results have been used to control the content of patulin in food products within and lower than the maximum allowable levels.

  20. Stable switching of resistive random access memory on the nanotip array electrodes

    KAUST Repository

    Tsai, Kun-Tong

    2016-09-13

    The formation/rupture of conducting filaments (CFs) in resistive random access memory (ReRAM) materials tune the electrical conductivities non-volatilely and are largely affected by its material composition [1], internal configurations [2] and external environments [3,4]. Therefore, controlling repetitive formation/rupture of CF as well as the spatial uniformity of formed CF are fundamentally important for improving the resistive switching (RS) performance. In this context, we have shown that by adding a field initiator, typically a textured electrode, both performance and switching uniformity of ReRAMs can be improved dramatically [5]. In addition, despite its promising characteristics, the scalable fabrication and structural homogeneity of such nanostructured electrodes are still lacking or unattainable, making miniaturization of ReRAM devices an exceeding challenge. Here, we employ nanostructured electrode (nanotip arrays, extremely uniform) formed spontaneously via a self-organized process to improve the ZnO ReRAM switching characteristics.

  1. Performance of Multi Walled Carbon Nanotubes Grown on Conductive Substrates as Supercapacitors Electrodes using Organic and Ionic liquid electrolytes

    Science.gov (United States)

    Winchester, Andrew; Ghosh, Sujoy; Turner, Ben; Zhang, X. F.; Talapatra, Saikat

    2012-02-01

    In this work we will present the use of Multi Walled Carbon Nanotubes (MWNT) directly grown on inconel substrates via chemical vapor deposition, as electrode materials for electrochemical double layer capacitors (EDLC). The performance of the MWNT EDLC electrodes were investigated using two electrolytes, an organic electrolyte, tetraethylammonium tetrafluoroborate in propylene carbonate (Et4NBF4 in PC), and a room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6). Cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy measurements to obtain values for the capacitance and internal resistance of these devices will be presented and compared.

  2. Formation of nanotubes in poly (vinylidene fluoride): Application as solid polymer electrolyte in DSC fabricated using carbon counter electrode

    Energy Technology Data Exchange (ETDEWEB)

    Muthuraaman, B. [Department of Energy, University of Madras, Guindy campus, Chennai 600025 (India); Maruthamuthu, P., E-mail: pmaruthu@yahoo.com [Department of Energy, University of Madras, Guindy campus, Chennai 600025 (India)

    2011-09-01

    Highlights: > Incorporation of a {pi}-electron donor compound as dopant in poly(vinylidene fluoride) along with redox couple (I{sup -}/I{sub 3}{sup -}) which forms brush like nanotubes. > Investigations about the use of conducting carbon coated FTO as a durable counter electrode and its effects in DSC. > High charge separation and the channelized flow of electrons in the nanotubes in electrolyte favors stable performance. - Abstract: In the present work, we report the incorporation of 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) in poly(vinylidene fluoride) (PVDF) along with the redox couple (I{sup -}/I{sub 3}{sup -}). When ABTS, a {pi}-electron donor, is used to dope PVDF, the polymer composite forms brush-like nanotubes and has been successfully used as a solid polymer electrolyte in dye-sensitized solar cells. Under the given conditions, the electrolyte composition forms nanotubes while it is doped with ABTS, a {pi}-electron donor. With this new electrolyte, a dye-sensitized solar cell was fabricated using N3 dye adsorbed over TiO{sub 2} nanoparticles as the photoanode and conducting carbon cement coated FTO as counter electrode.

  3. Analysis of polyphenols in white wine by CZE with amperometric detection using carbon nanotube-modified electrodes.

    Science.gov (United States)

    Moreno, Mónica; Arribas, Alberto Sánchez; Bermejo, Esperanza; Zapardiel, Antonio; Chicharro, Manuel

    2011-04-01

    A method for the simultaneous detection of five polyphenols (caffeic, chlorogenic, ferulic and gallic acids and (+)-catechin) by CZE with electrochemical detection was developed. Separation of these polyphenols was performed in a 100 mM borate buffer (pH 9.2) within 15 min. Under optimized separation conditions, the performance of glassy carbon (GC) electrodes modified with multiwalled carbon nanotube layer obtained from different dispersions was examined. GC electrode modified with a dispersion of multi-walled carbon nanotubes (CNT) in polyethylenimine has proven to be the most suitable CNT-based electrode for its application as amperometric detector for the CZE separation of the studied compounds. The excellent electrochemical properties of this electrode allowed the detection of the selected polyphenols at +200 mV and improved the efficiency and the resolution of their CZE separation. Limits of detection below 3.1 μM were obtained with linear ranges covering the 10⁻⁵ to 10⁻⁴  M range. The proposed method has been successfully applied for the detection (ferulic, caffeic and gallic acids and (+)-catechin) and the quantification (gallic acid and (+)-catechin) of polyphenols in two different white wines without any preconcentration step. A remarkable signal stability was observed on the electrode performance despite the presence of potential fouling substances in wine. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Electrochemical deposition of gold nanoparticles on carbon nanotube coated glassy carbon electrode for the improved sensing of tinidazole

    International Nuclear Information System (INIS)

    Shahrokhian, Saeed; Rastgar, Shokoufeh

    2012-01-01

    The electrochemical reduction of tinidazole (TNZ) is studied on gold-nanoparticle/carbon-nanotubes (AuNP/CNT) modified glassy carbon electrodes using the linear sweep voltammetry. An electrochemical procedure was used for the deposition of gold nanoparticles onto the carbon nanotube film pre-cast on a glassy carbon electrode surface. The resulting nanoparticles were characterized by scanning electron microscopy and cyclic voltammetry. The effect of the electrodeposition conditions, e.g., salt concentration and deposition time on the response of the electrode was studied. Also, the effect of experimental parameters, e.g., potential and time of accumulation, pH of the buffered solutions and the potential sweep rate on the response is examined. Under the optimal conditions, the modified electrode showed a wide linear response toward the concentration of TNZ in the range of 0.1–50 μM with a detection limit of 10 nM. The prepared electrode was successfully applied for the determination of TNZ in pharmaceutical and clinical samples.

  5. Fabrication of Flexible Microneedle Array Electrodes for Wearable Bio-Signal Recording

    Directory of Open Access Journals (Sweden)

    Lei Ren

    2018-04-01

    Full Text Available Laser-direct writing (LDW and magneto-rheological drawing lithography (MRDL have been proposed for the fabrication of a flexible microneedle array electrode (MAE for wearable bio-signal monitoring. Conductive patterns were directly written onto the flexible polyethylene terephthalate (PET substrate by LDW. The microneedle array was rapidly drawn and formed from the droplets of curable magnetorheological fluid with the assistance of an external magnetic field by MRDL. A flexible MAE can maintain a stable contact interface with curved human skin due to the flexibility of the PET substrate. Compared with Ag/AgCl electrodes and flexible dry electrodes (FDE, the electrode–skin interface impedance of flexible MAE was the minimum even after a 50-cycle bending test. Flexible MAE can record electromyography (EMG, electroencephalography (EEG and static electrocardiography (ECG signals with good fidelity. The main features of the dynamic ECG signal recorded by flexible MAE are the most distinguishable with the least moving artifacts. Flexible MAE is an attractive candidate electrode for wearable bio-signal monitoring.

  6. Fabrication of a Micro-Needle Array Electrode by Thermal Drawing for Bio-Signals Monitoring.

    Science.gov (United States)

    Ren, Lei; Jiang, Qing; Chen, Keyun; Chen, Zhipeng; Pan, Chengfeng; Jiang, Lelun

    2016-06-17

    A novel micro-needle array electrode (MAE) fabricated by thermal drawing and coated with Ti/Au film was proposed for bio-signals monitoring. A simple and effective setup was employed to form glassy-state poly (lactic-co-glycolic acid) (PLGA) into a micro-needle array (MA) by the thermal drawing method. The MA was composed of 6 × 6 micro-needles with an average height of about 500 μm. Electrode-skin interface impedance (EII) was recorded as the insertion force was applied on the MAE. The insertion process of the MAE was also simulated by the finite element method. Results showed that MAE could insert into skin with a relatively low compression force and maintain stable contact impedance between the MAE and skin. Bio-signals, including electromyography (EMG), electrocardiography (ECG), and electroencephalograph (EEG) were also collected. Test results showed that the MAE could record EMG, ECG, and EEG signals with good fidelity in shape and amplitude in comparison with the commercial Ag/AgCl electrodes, which proves that MAE is an alternative electrode for bio-signals monitoring.

  7. Fabrication of a Micro-Needle Array Electrode by Thermal Drawing for Bio-Signals Monitoring

    Directory of Open Access Journals (Sweden)

    Lei Ren

    2016-06-01

    Full Text Available A novel micro-needle array electrode (MAE fabricated by thermal drawing and coated with Ti/Au film was proposed for bio-signals monitoring. A simple and effective setup was employed to form glassy-state poly (lactic-co-glycolic acid (PLGA into a micro-needle array (MA by the thermal drawing method. The MA was composed of 6 × 6 micro-needles with an average height of about 500 μm. Electrode-skin interface impedance (EII was recorded as the insertion force was applied on the MAE. The insertion process of the MAE was also simulated by the finite element method. Results showed that MAE could insert into skin with a relatively low compression force and maintain stable contact impedance between the MAE and skin. Bio-signals, including electromyography (EMG, electrocardiography (ECG, and electroencephalograph (EEG were also collected. Test results showed that the MAE could record EMG, ECG, and EEG signals with good fidelity in shape and amplitude in comparison with the commercial Ag/AgCl electrodes, which proves that MAE is an alternative electrode for bio-signals monitoring.

  8. Electrical stimulus artifact cancellation and neural spike detection on large multi-electrode arrays.

    Science.gov (United States)

    Mena, Gonzalo E; Grosberg, Lauren E; Madugula, Sasidhar; Hottowy, Paweł; Litke, Alan; Cunningham, John; Chichilnisky, E J; Paninski, Liam

    2017-11-01

    Simultaneous electrical stimulation and recording using multi-electrode arrays can provide a valuable technique for studying circuit connectivity and engineering neural interfaces. However, interpreting these measurements is challenging because the spike sorting process (identifying and segregating action potentials arising from different neurons) is greatly complicated by electrical stimulation artifacts across the array, which can exhibit complex and nonlinear waveforms, and overlap temporarily with evoked spikes. Here we develop a scalable algorithm based on a structured Gaussian Process model to estimate the artifact and identify evoked spikes. The effectiveness of our methods is demonstrated in both real and simulated 512-electrode recordings in the peripheral primate retina with single-electrode and several types of multi-electrode stimulation. We establish small error rates in the identification of evoked spikes, with a computational complexity that is compatible with real-time data analysis. This technology may be helpful in the design of future high-resolution sensory prostheses based on tailored stimulation (e.g., retinal prostheses), and for closed-loop neural stimulation at a much larger scale than currently possible.

  9. Fabrication of a gas sensor array with micro-wells for VOCs gas sensing based on polymer/carbon nanotube thin films

    Science.gov (United States)

    Xie, Guangzhong; Xie, Tao; Zhu, Tao; Jiang, Yadong; Tai, Huiling

    2014-08-01

    In this paper, gas sensor array with micro-well was designed and prepared by Micro Electro-Mechanical Systems (MEMS) technology. The micro-well and interdigital electrodes of sensor array were prepared using photolithography process, reactive ion etching (RIE) process, wet etching and conventional vacuum evaporation. In the manufacture process of the gas sensor array, KOH wet etching process was mainly discussed. The optimum etching processing parameters were as follows: 30 wt% KOH solution at 80 °C, a cooling back-flow device and a magnetic stirrer. The multi-walled carbon nanotubes (MWCNTs)-polyethyleneoxide (PEO) and MWNTs-Polyvinylpyrrolidone (PVP) composite films were utilized as sensitive layers to test gas-sensing properties. Response performances of MWCNTs- PEO and MWNTs-PVP composite films to toluene vapor and methanol vapor at room temperature were investigated. The results revealed that the sensor array showed a larger sensitivity to toluene vapor than to methanol vapor. In addition, the sensing mechanisms were studied as well.

  10. Vertically-aligned carbon nanotubes on aluminum as a light-weight positive electrode for lithium-polysulfide batteries.

    Science.gov (United States)

    Liatard, S; Benhamouda, K; Fournier, A; Ramos, R; Barchasz, C; Dijon, J

    2015-05-04

    A light-weight, high specific surface current collector made of vertically-aligned carbon nanotubes grown on an aluminum substrate was fabricated and studied as a positive electrode in a semi-liquid lithium/polysulfide battery. This simple system delivered stable capacities over 1000 mA h gS(-1) and 2 mA h cm(-2) with almost no capacity loss over 50 cycles.

  11. Long-term stability of intracortical recordings using perforated and arrayed Parylene sheath electrodes

    Science.gov (United States)

    Hara, Seth A.; Kim, Brian J.; Kuo, Jonathan T. W.; Lee, Curtis D.; Meng, Ellis; Pikov, Victor

    2016-12-01

    Objective. Acquisition of reliable and robust neural recordings with intracortical neural probes is a persistent challenge in the field of neuroprosthetics. We developed a multielectrode array technology to address chronic intracortical recording reliability and present in vivo recording results. Approach. The 2 × 2 Parylene sheath electrode array (PSEA) was microfabricated and constructed from only Parylene C and platinum. The probe includes a novel three-dimensional sheath structure, perforations, and bioactive coatings that improve tissue integration and manage immune response. Coatings were applied using a sequential dip-coating method that provided coverage over the entire probe surface and interior of the sheath structure. A sharp probe tip taper facilitated insertion with minimal trauma. Fabricated probes were subject to examination by optical and electron microscopy and electrochemical testing prior to implantation. Main results. 1 × 2 arrays were successfully fabricated on wafer and then packaged together to produce 2 × 2 arrays. Then, probes having electrode sites with adequate electrochemical properties were selected. A subset of arrays was treated with bioactive coatings to encourage neuronal growth and suppress inflammation and another subset of arrays was implanted in conjunction with a virally mediated expression of Caveolin-1. Arrays were attached to a custom-made insertion shuttle to facilitate precise insertion into the rat motor cortex. Stable electrophysiological recordings were obtained during the period of implantation up to 12 months. Immunohistochemical evaluation of cortical tissue around individual probes indicated a strong correlation between the electrophysiological performance of the probes and histologically observable proximity of neurons and dendritic sprouting. Significance. The PSEA demonstrates the scalability of sheath electrode technology and provides higher electrode count and density to access a greater volume for recording

  12. Enhanced field emission properties of vertically aligned double-walled carbon nanotube arrays

    International Nuclear Information System (INIS)

    Chen, Guohai; Shin, Dong Hoon; Lee, Cheol Jin; Iwasaki, Takayuki; Kawarada, Hiroshi

    2008-01-01

    Vertically aligned double-walled carbon nanotube (VA-DWCNT) arrays were synthesized by point-arc microwave plasma chemical vapor deposition on Cr/n-Si and SiO 2 /n-Si substrates. The outer tube diameters of VA-DWCNTs are in the range of 2.5-3.8 nm, and the average interlayer spacing is approximately 0.42 nm. The field emission properties of these VA-DWCNTs were studied. It was found that a VA-DWCNT array grown on a Cr/n-Si substrate had better field emission properties as compared with a VA-DWCNT array grown on a SiO 2 /n-Si substrate and randomly oriented DWCNTs, showing a turn-on field of about 0.85 V μm -1 at the emission current density of 0.1 μA cm -2 and a threshold field of 1.67 V μm -1 at the emission current density of 1.0 mA cm -2 . The better field emission performance of the VA-DWCNT array was mainly attributed to the vertical alignment of DWCNTs on the Cr/n-Si substrate and the low contact resistance between CNTs and the Cr/n-Si substrate

  13. On-Chip Sorting of Long Semiconducting Carbon Nanotubes for Multiple Transistors along an Identical Array.

    Science.gov (United States)

    Otsuka, Keigo; Inoue, Taiki; Maeda, Etsuo; Kometani, Reo; Chiashi, Shohei; Maruyama, Shigeo

    2017-11-28

    Ballistic transport and sub-10 nm channel lengths have been achieved in transistors containing one single-walled carbon nanotube (SWNT). To fill the gap between single-tube transistors and high-performance logic circuits for the replacement of silicon, large-area, high-density, and purely semiconducting (s-) SWNT arrays are highly desired. Here we demonstrate the fabrication of multiple transistors along a purely semiconducting SWNT array via an on-chip purification method. Water- and polymer-assisted burning from site-controlled nanogaps is developed for the reliable full-length removal of metallic SWNTs with the damage to s-SWNTs minimized even in high-density arrays. All the transistors with various channel lengths show large on-state current and excellent switching behavior in the off-state. Since our method potentially provides pure s-SWNT arrays over a large area with negligible damage, numerous transistors with arbitrary dimensions could be fabricated using a conventional semiconductor process, leading to SWNT-based logic, high-speed communication, and other next-generation electronic devices.

  14. Fringing-field dielectrophoretic assembly of ultrahigh-density semiconducting nanotube arrays with a self-limited pitch

    Science.gov (United States)

    Cao, Qing; Han, Shu-Jen; Tulevski, George S.

    2014-09-01

    One key challenge of realizing practical high-performance electronic devices based on single-walled carbon nanotubes is to produce electronically pure nanotube arrays with both a minuscule and uniform inter-tube pitch for sufficient device-packing density and homogeneity. Here we develop a method in which the alternating voltage-fringing electric field formed between surface microelectrodes and the substrate is utilized to assemble semiconducting nanotubes into well-aligned, ultrahigh-density and submonolayered arrays, with a consistent pitch as small as 21±6 nm determined by a self-limiting mechanism, based on the unique field focusing and screening effects of the fringing field. Field-effect transistors based on such nanotube arrays exhibit record high device transconductance (>50 μS μm-1) and decent on current per nanotube (~1 μA per tube) together with high on/off ratios at a drain bias of -1 V.

  15. 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.

  16. A Novel of Buton Asphalt and Methylene Blue as Dye-Sensitized Solar Cell using TiO2/Ti Nanotubes Electrode

    Science.gov (United States)

    Nurhidayani; Muzakkar, M. Z.; Maulidiyah; Wibowo, D.; Nurdin, M.

    2017-11-01

    A study of TiO2/Ti nanotubes arrays (NTAs) based on Dye-Sensitized Solar Cell (DSSC) used Asphalt Buton (Asbuton) extract and methylene blue (MB) as a photosensitizer dye has been conducted. The aim of this research is that the Asbuton extract and Methylene Blue (MB) performance as a dye on DSSC solar cells is able to obtain the voltage-currents produced by visible light irradiation. Electrode TiO2/Ti NTAs have been successfully synthesized by anodizing methods, then characterized by using XRD showed that the anatase crystals formed. Subsequently, the morphology showed that the nanotubes formed which has coated by Asbuton extract. The DSSC system was formed by a sandwich structure and tested by using Multimeter Digital with Potentiostat instrument. The characteristics of current (I) and potential (V) versus time indicated that the Asbuton was obtained in a high-performance in 30s of 14,000µV 0.844µA, meanwhile MB dyes were 8,000µV0.573µA. Based on this research, the Asbuton extract from Buton Island-Southeast Sulawesi-Indonesia was potential for natural dyes in DSSC system.

  17. IrOx-carbon nanotube hybrids: a nanostructured material for electrodes with increased charge capacity in neural systems.

    Science.gov (United States)

    Carretero, Nina M; Lichtenstein, Mathieu P; Pérez, Estela; Cabana, Laura; Suñol, Cristina; Casañ-Pastor, Nieves

    2014-10-01

    Nanostructured iridium oxide-carbon nanotube hybrids (IrOx-CNT) deposited as thin films by dynamic electrochemical methods are suggested as novel materials for neural electrodes. Single-walled carbon nanotubes (SWCNT) serve as scaffolds for growing the oxide, yielding a tridimensional structure with improved physical, chemical and electrical properties, in addition to high biocompatibility. In biological environments, SWCNT encapsulation by IrOx makes more resistant electrodes and prevents the nanotube release to the media, preventing cellular toxicity. Chemical, electrochemical, structural and surface characterization of the hybrids has been accomplished. The high performance of the material in electrochemical measurements and the significant increase in cathodal charge storage capacity obtained for the hybrid in comparison with bare IrOx represent a significant advance in electric field application in biosystems, while its cyclability is also an order of magnitude greater than pure IrOx. Moreover, experiments using in vitro neuronal cultures suggest high biocompatibility for IrOx-CNT coatings and full functionality of neurons, validating this material for use in neural electrodes. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  18. Synthesis and photoelectrical performance of nanoscale PbS and Bi2S3 co-sensitized on Ti02 nanotube arrays

    Institute of Scientific and Technical Information of China (English)

    Fanggong Cai; Min Pan; Yong Feng; Guo Yan; Yong Zhang; Yong Zhao

    2017-01-01

    TiO2 films have been widely applied in photovoltaic conversion techniques.TiO2 nanotube arrays (TiO2 NAs) can be grown directly on the surface of metal Ti by the anodic oxidation method.Bi2S3 and PbS nanoparticles (NPs) were firstly co-sensitized on TiO2 NAs (denoted as PbS/Bi2S3(n)/TiO2 NAs) by a two-step process containing hydrothermal and sonication-assisted SILAR method.When the concentration of Bi3+ is 5 mmol/L,the best photoelectrical performance was obtained under simulated solar irradiation.The short-circuit photocurrent (Jsc) and photoconversion efficiency (η) of PbS/Bi2S3(5)/TiO2 NAs electrode were 4.70 mA/cm and 1.13 %,respectively.

  19. Initial Operative Experience and Short-term Hearing Preservation Results With a Mid-scala Cochlear Implant Electrode Array.

    Science.gov (United States)

    Svrakic, Maja; Roland, J Thomas; McMenomey, Sean O; Svirsky, Mario A

    2016-12-01

    To describe our initial operative experience and hearing preservation results with the Advanced Bionics (AB) Mid Scala Electrode (MSE). Retrospective review. Tertiary referral center. Sixty-three MSE implants in pediatric and adult patients were compared with age- and sex-matched 1j electrode implants from the same manufacturer. All patients were severe to profoundly deaf. Cochlear implantation with either the AB 1j electrode or the AB MSE. The MSE and 1j electrodes were compared in their angular depth of insertion and pre to postoperative change in hearing thresholds. Hearing preservation was analyzed as a function of angular depth of insertion. Secondary outcome measures included operative time, incidence of abnormal intraoperative impedance and telemetry values, and incidence of postsurgical complications. Depth of insertion was similar for both electrodes, but was more consistent for the MSE array and more variable for the 1j array. Patients with MSE electrodes had better hearing preservation. Thresholds shifts at four audiometric frequencies ranging from 250 to 2000 Hz were 10, 7, 2, and 6 dB smaller for the MSE electrode than for the 1j (p < 0.05). Hearing preservation at low frequencies was worse with deeper insertion, regardless of array. Secondary outcome measures were similar for both electrodes. The MSE electrode resulted in more consistent insertion depth and somewhat better hearing preservation than the 1j electrode. Differences in other surgical outcome measures were small or unlikely to have a meaningful effect.

  20. Hierarchical Mesoporous Zinc-Nickel-Cobalt Ternary Oxide Nanowire Arrays on Nickel Foam as High-Performance Electrodes for Supercapacitors.

    Science.gov (United States)

    Wu, Chun; Cai, Junjie; Zhang, Qiaobao; Zhou, Xiang; Zhu, Ying; Shen, Pei Kang; Zhang, Kaili

    2015-12-09

    Nickel foam supported hierarchical mesoporous Zn-Ni-Co ternary oxide (ZNCO) nanowire arrays are synthesized by a simple two-step approach including a hydrothermal method and subsequent calcination process and directly utilized for supercapacitive investigation for the first time. The nickel foam supported hierarchical mesoporous ZNCO nanowire arrays possess an ultrahigh specific capacitance value of 2481.8 F g(-1) at 1 A g(-1) and excellent rate capability of about 91.9% capacitance retention at 5 A g(-1). More importantly, an asymmetric supercapacitor with a high energy density (35.6 Wh kg(-1)) and remarkable cycle stability performance (94% capacitance retention over 3000 cycles) is assembled successfully by employing the ZNCO electrode as positive electrode and activated carbon as negative electrode. The remarkable electrochemical behaviors demonstrate that the nickel foam supported hierarchical mesoporous ZNCO nanowire array electrodes are highly desirable for application as advanced supercapacitor electrodes.

  1. Tissue Damage, Temperature, and pH Induced by Different Electrode Arrays on Potato Pieces (Solanum tuberosum L.

    Directory of Open Access Journals (Sweden)

    Maraelys Morales González

    2018-04-01

    Full Text Available One of the most challenging problems of electrochemical therapy is the design and selection of suitable electrode array for cancer. The aim is to determine how two-dimensional spatial patterns of tissue damage, temperature, and pH induced in pieces of potato (Solanum tuberosum L., var. Mondial depend on electrode array with circular, elliptical, parabolic, and hyperbolic shape. The results show the similarity between the shapes of spatial patterns of tissue damage and electric field intensity, which, like temperature and pH take the same shape of electrode array. The adequate selection of suitable electrodes array requires an integrated analysis that involves, in a unified way, relevant information about the electrochemical process, which is essential to perform more efficiently way the therapeutic planning and the personalized therapy for patients with a cancerous tumor.

  2. Nickel hydroxide–carbon nanotube nanocomposites as supercapacitor electrodes: crystallinity dependent performances

    International Nuclear Information System (INIS)

    Jiang, Wenchao; Zhai, Shengli; Wei, Li; Yuan, Yang; Yu, Dingshan; Chen, Yuan; Wang, Liang; Wei, Jun

    2015-01-01

    Nickel hydroxide (Ni(OH)_2) is a promising pseudocapacitive material to increase the energy storage capacity of supercapacitors. Ni(OH)_2 has three common crystalline structures: amorphous (amor-), α-, and β-Ni(OH)_2. There is a lack of good understanding on their pros and cons as supercapacitor electrodes. In this work, we synthesized three nanocomposites with thin layers (10–15 nm) of amor-, α-, and β-Ni(OH)_2 deposited on conductive multi-walled carbon nanotubes (MWCNTs). The mass loading of Ni(OH)_2 is analogous in these nanocomposites, ranging from 49.1–52.2 wt% with a comparable narrow-pore size distribution centered around 4–5 nm. They were fabricated into supercapacitor electrodes at a mass loading of 6 mg cm"−"2 with a thickness of ∼250 μm, similar to the electrodes used in commercial supercapacitors. Our results show that MWCNT/amor-Ni(OH)_2 has the highest specific capacitance (1495 or 2984 F g"−"1, based on the mass of total active materials or Ni(OH)_2 only at the scan rate of 5 mV s"−"1 in 1 M KOH electrolyte). It also has the best rate capability among the three nanocomposites. Better performances can be attributed to its disordered structure, which increases its effective surface area and reduces diffusion resistance for redox reactions. However, superior performances gradually deteriorate to the same level as that of MWCNT/β-Ni(OH)_2 over 3000 charge/discharge cycles, because amor- and α-Ni(OH)_2 transform slowly to more ordered β-Ni(OH)_2. Our results highlight that the electrochemical performances of MWCNT/Ni(OH)_2 nanocomposites depend on the crystallinity of Ni(OH)_2, and the performances of electrodes change upon the crystalline structure transformation of Ni(OH)_2 under repeated redox reactions. Future research should focus on improving the structure stability of amor-Ni(OH)_2. (paper)

  3. INFLUENCE OF IONIZING IRRADIATION ON THE PARAMETERS OF ZN NANOTUBES ARRAYS FOR DESIGN OF FLEXIBLE ELECTRONICS ELEMENTS

    Directory of Open Access Journals (Sweden)

    D. B. Kadyrzhanov

    2018-01-01

    Full Text Available The aim of the study is establishing the possibility of using Zn nanotube arrays as a basis for design compact and lightweight elements of flexible electronics, including operating under influence of ionizing irradiation.The paper presents the results of the synthesis of Zn nanotubes obtained by electrochemical deposition in the pores of polymer matrices and the study of their structural and electrophysical properties after directional modification by ionizing radiation with different doses. Using the methods of scanning electron microscopy, X-ray diffraction and energy dispersive analysis, the structure of nanotubes having a polycrystalline structure and completely consisting of zinc was studied and it was demonstrated that irradiation with Ar8+ ions with a dose from 1 × 109 to 5 × 1011 ion/cm2 and energy 1.75 MeV/nucleon has an effect on the crystal structure of nanotubes.At high doses, localized highly defect zones arise, leading to a critical change in the structure and physical properties of the nanotubes, respectively. It is shown that the consequence of the modification of the crystal structure is a change in the electrical conductivity of nanotubes: at low doses the electrical conductivity increases, but when the threshold value is reached, it sharply decreases. The change in the crystal structure and the corresponding changes in the conductive properties of Zn nanotubes due to irradiation determine the mechanism of ionizing radiation influence on nanomaterials and determine the possibility of using Zn nanotubes arrays as a basis for creating compact and lightweight elements of flexible electronics.

  4. Amperometric Morphine Detection Using Pt-Co Alloy Nanowire Array-modified Electrode

    International Nuclear Information System (INIS)

    Tao, Manlan; Xu, Feng; Li, Yueting; Xu, Quanqing; Chang, Yanbing; Yang, Yunhui; Wu, Zaisheng

    2010-01-01

    Pt-Co alloy nanowire array was directly synthesized by electrochemical deposition with polycarbonate template at -1.0V and subsequent chemical etching of the template. The use of Pt-Co alloy nanowire array-modified electrode (Pt- Co NAE) for the determination of morphine (MO) is described. The morphology of the Pt-Co alloy nanowire array has been investigated by scanning electron microscopy (SEM) and energy disperse X-ray spectroscopy (EDS) analysis), respectively. The resulting Pt-Co NAE offered a linear amperometric response for morphine ranging from 2.35 x 10 -5 to 2.39 x 10 -3 M with a detection limit of 7.83 x 10 -6 M at optimum conditions. This sensor displayed high sensitivity and long-term stability

  5. Electrochemically synthesized visible light absorbing vertically aligned N-doped TiO2 nanotube array films

    International Nuclear Information System (INIS)

    Antony, Rajini P.; Mathews, Tom; Ajikumar, P.K.; Krishna, D. Nandagopala; Dash, S.; Tyagi, A.K.

    2012-01-01

    Graphical abstract: Display Omitted Highlights: ► Single step electrochemical synthesis of N-doped TiO 2 nanotube array films. ► Effective substitutional N-doping achieved. ► Different N-concentrations were achieved by varying the N-precursor concentration in the electrolyte. ► Visible light absorption observed at high N-doping. -- Abstract: Visible light absorbing vertically aligned N-doped anatase nanotube array thin films were synthesized by anodizing Ti foils in ethylene glycol + NH 4 F + water mixture containing urea as nitrogen source. Different nitrogen concentrations were achieved by varying the urea content in the electrolyte. The structure, morphology, composition and optical band gap of the nanotube arrays were determined by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and diffuse reflectance spectroscopy, respectively. The substitution of O 2− ions by N 3− ions in the anion sublattice as well as the formulae of the doped samples was confirmed from the results of XPS. The optical band gap of the nanotube arrays was found to decrease with N-concentration. The sample with the highest concentration corresponding to the formula TiO 1.83 N 0.14 showed two regions in the Tauc's plot indicating the presence of interband states.

  6. Pt nanoparticle modified single walled carbon nanotube network electrodes for electrocatalysis: control of the specific surface area over three orders of magnitude

    NARCIS (Netherlands)

    Miller, T.S.; Sansuk, S.; Lai, Stanley; Macpherson, J.V.; Unwin, P.R.

    2015-01-01

    The electrodeposition of Pt nanoparticles (NPs) on two-dimensional single walled carbon nanotube (SWNT) network electrodes is investigated as a means of tailoring electrode surfaces with a well-defined amount of electrocatalytic material. Both Pt NP deposition and electrocatalytic studies are

  7. Preparation of TiO2-based nanotubes/nanoparticles composite thin film electrodes for their electron transport properties

    International Nuclear Information System (INIS)

    Zhao, Wanyu; Fu, Wuyou;