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Sample records for composite electrode applications

  1. Electrode compositions

    DOEpatents

    Block, J.; Fan, X.

    1998-10-27

    An electrode composition is described for use as an electrode in a non-aqueous battery system. The electrode composition contains an electrically active powder in a solid polymer and, as a dispersant, a C{sub 8}-C{sub 15} alkyl capped oligomer of a hexanoic acid that is electrochemically inert at 2.5--4.5 volts.

  2. Electrode compositions

    DOEpatents

    Block, Jacob; Fan, Xiyun

    1998-01-01

    An electrode composition for use as an electrode in a non-aqueous battery system. The electrode composition contains an electrically active powder in a solid polymer and, as a dispersant, a C.sub.8 -C.sub.15 alkyl capped oligomer of a hexanoic acid that is electrochemically inert at 2.5-4.5 volts.

  3. Composite carbon foam electrode

    DOEpatents

    Mayer, S.T.; Pekala, R.W.; Kaschmitter, J.L.

    1997-05-06

    Carbon aerogels used as a binder for granulated materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivity and power to system energy. 1 fig.

  4. Composite carbon foam electrode

    DOEpatents

    Mayer, Steven T.; Pekala, Richard W.; Kaschmitter, James L.

    1997-01-01

    Carbon aerogels used as a binder for granularized materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivty and power to system energy.

  5. Electrochemical Synthesis of Graphene/MnO2 Nano-Composite for Application to Supercapacitor Electrode.

    PubMed

    Jeong, Kwang Ho; Lee, Hyeon Jeong; Simpson, Michael F; Jeong, Mun

    2016-05-01

    Graphene/MnO2 nano-composite was electrochemically synthesized for application to an electrode material for electrochemical supercapacitors. The nanosized needle-like MnO2 was obtained by use of a graphene substrate. The prepared composite exhibited an ideal supercapacitive behavior. A capacitance retention of 94% was achieved with a 4 h deposition time (an initial capacitance of 574 mF/cm2 at a scan rate of 20 mV/s) and the retention declined with further deposition time. The results demonstrate enhanced contact between the electrode and electrolyte and improved power density as an electrochemical capacitor. PMID:27483800

  6. Negative electrode composition

    DOEpatents

    Kaun, Thomas D.; Chilenskas, Albert A.

    1982-01-01

    A secondary electrochemical cell and a negative electrode composition for use therewith comprising a positive electrode containing an active material of a chalcogen or a transiton metal chalcogenide, a negative electrode containing a lithium-aluminum alloy and an amount of a ternary alloy sufficient to provide at least about 5 percent overcharge capacity relative to a negative electrode solely of the lithium-aluminum alloy, the ternary alloy comprising lithium, aluminum, and iron or cobalt, and an electrolyte containing lithium ions in contact with both of the positive and the negative electrodes. The ternary alloy is present in the electrode in the range of from about 5 percent to about 50 percent by weight of the electrode composition and may include lithium-aluminum-nickel alloy in combination with either the ternary iron or cobalt alloys. A plurality of series connected cells having overcharge capacity can be equalized on the discharge side without expensive electrical equipment.

  7. Uncharged positive electrode composition

    DOEpatents

    Kaun, Thomas D.; Vissers, Donald R.; Shimotake, Hiroshi

    1977-03-08

    An uncharged positive-electrode composition contains particulate lithium sulfide, another alkali metal or alkaline earth metal compound other than sulfide, e.g., lithium carbide, and a transition metal powder. The composition along with a binder, such as electrolytic salt or a thermosetting resin is applied onto an electrically conductive substrate to form a plaque. The plaque is assembled as a positive electrode within an electrochemical cell opposite to a negative electrode containing a material such as aluminum or silicon for alloying with lithium. During charging, lithium alloy is formed within the negative electrode and transition metal sulfide such as iron sulfide is produced within the positive electrode. Excess negative electrode capacity over that from the transition metal sulfide is provided due to the electrochemical reaction of the other than sulfide alkali metal or alkaline earth metal compound.

  8. Application of Desalination with CFRP Composite Electrode to Concrete Deteriorated by Chloride Attack

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Keisuke; Ueda, Takao; Nanasawa, Akira

    As a new rehabilitation technique for recovery both of loading ability and durability of concrete structures deteriorated by chloride attack, desalination (electrochemical chloride removal technique from concrete) using CFRP composite electrode bonding to concrete has been developed. In this study, basic application was tried using small RC specimens, and also application to the large-scale RC beams deteriorated by the chloride attack through the long-term exposure in the outdoors was investigated. As the result of bending test of treated specimens, the decrease of strengthening effect with the electrochemical treatment was observed in the case of small specimens using low absorption rate resin for bonding, on the other hand, in the case of large-scale RC beam using 20% absorption rate resin for bonding CFRP composite electrode, enough strengthening effect was obtained by the bending failure of RC beam with the fracture of CFRP board.

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

    PubMed

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

    2016-03-01

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

  10. Method for uniformly distributing carbon flakes in a positive electrode, the electrode made thereby and compositions. [Patent application

    DOEpatents

    Mrazek, F.C.; Smaga, J.A.; Battles, J.E.

    1981-01-19

    A positive electrode for a secondary electrochemical cell is described wherein an electrically conductive current collector is in electrical contact with a particulate mixture of gray cast iron and an alkali metal sulfide and an electrolyte including alkali metal halides or alkaline earth metal halides. Also present may be a transition metal sulfide and graphite flakes from the conversion of gray cast iron to iron sulfide. Also disclosed is a method of distributing carbon flakes in a cell wherein there is formed an electrochemical cell of a positive electrode structure of the type described and a suitable electrolyte and a second electrode containing a material capable of alloying with alkali metal ions. The cell is connected to a source of electrical potential to electrochemically convert gray cast iron to an iron sulfide and uniformly to distribute carbon flakes formerly in the gray cast iron throughout the positive electrode while forming an alkali metal alloy in the negative electrode. Also disclosed are compositions useful in preparing positive electrodes.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  12. Continuity and Performance in Composite Electrodes

    SciTech Connect

    Chen, Guoying; Richardson, Thomas J.

    2009-12-23

    It is shown that the rate performance of a lithium battery composite electrode may be compromised by poor internal connectivity due to defects and inhomogeneities introduced during electrode fabrication or subsequent handling. Application of a thin conductive coating to the top surface of the electrode or to the separator surface in contact with the electrode improves the performance by providing alternative current paths to partially isolated particles of electroactive material. Mechanistic implications are discussed and strategies for improvement in electrode design and fabrication are presented.

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  14. Investigation of the properties of polyacrylamide-polyaniline composite and its application as a battery electrode

    SciTech Connect

    Bhat, N.V.; Joshi, N.V. . Dept. of Chemical Technology)

    1993-11-20

    The composite films of polyacrylamide and polyaniline were prepared by polymerizing aniline using ammonium persulfate as an initiator in an aqueous solution containing poly-acrylamide. A film was then cast from this solution. The structural, dynamic mechanical, electrical, and thermal properties of these films have been studied. The infrared spectrum shows the presence of polyacrylamide as well as polyaniline in the composite film. The thermal analysis shows that the composite degrades slower than does the polyacrylamide alone. The dynamic mechanical analysis indicates that there is an increase in the glass transition temperature after the composite formation. The electrical conductivity has been found to increase by more than eight orders of magnitude. These composite films have also been suitably used as electrodes in secondary batteries.

  15. Fabrication and characterization of polyaniline-graphene nanoplatelets composite electrode materials for hybrid supercapacitor applications

    NASA Astrophysics Data System (ADS)

    Shi, HaoTian H.; Naguib, Hani E.

    2015-04-01

    Supercapacitor device electrochemical performance characteristics of different nanocomposite materials containing polyaniline (PAni) and graphene nanoplatelets (GnPs) have been evaluated with two-electrode electrochemical setup. The PAni-based nanocomposite electrodes have been fabricated via ultrasonicated in-situ chemical polymerization and solvent casting process. The specific capacitance of the supercapacitor electrode have reached as high as 357.07 F/g at 10mV/s, in the case of 15:1 PAni/GnPs, as a result of graphene nanoparticles' large surface area providing an ideal template for polymerization to occur. Electrodes under study are namely, pristine GnPs, pristine PAni, and 5:1, 15:1 PAni/GnPs nanocomposites. Material composition has been confirmed via thermal gravimetric analysis (TGA), while scanning electron microscopy (SEM) has been used to characterize the morphologies of the nanostructures. Threedimensional nanocomposite morphology has been observed in the micrographs of these nanocomposites, indicating a relationship between the material surface area and the charge storage ability.

  16. High charge density conducting polymer/graphite fiber composite electrodes for battery applications

    SciTech Connect

    Coffey, B.; Madsen, P.V.; Poehler, T.O.; Searson, P.C.

    1995-02-01

    Novel composite electrode structures have been fabricated by single-step electropolymerization of polypyrrole onto a porous graphite fiber matrix. The graphite substrate provides a lightweight structure with high surface area. The available charge capacity of the composite electrodes was proportional to the electropolymerization time and the mass of electroactive polymer with reversible charge capacities in excess of 4.0 C/cm{sup 2} and a specific capacity of 90 mAh/g, independent of polymer mass. The rate of charge extraction was dependent on the polymer mass and the morphology of the polymer electrode. In test cells using a polypyrrole/graphite fiber anode and a polypyrrole-polystyrene sulfonate/graphite fiber cathode, the authors have demonstrated a capacity of more than 40 mAh/g based on the active mass of the undoped polymer on discharging the cell to 0.1 V over a 10 k{Omega} load. More than 70% of the available charge was extracted from the cell over 50 cycles with no degradation of cell performance.

  17. Fabrication and application of flexible graphene silk composite film electrodes decorated with spiky Pt nanospheres.

    PubMed

    Liang, Bo; Fang, Lu; Hu, Yichuan; Yang, Guang; Zhu, Qin; Ye, Xuesong

    2014-04-21

    A free-standing graphene silk composite (G/S) film was fabricated via vacuum filtration of a mixed suspension of graphene oxide and silk fibres, followed by chemical reduction. Spiky structured Pt nanospheres were grown on the film substrate by cyclic voltammetry electrodeposition. The electrical and mechanical performance of a single graphene coated silk fibre was investigated. The conductivity of a single graphene coated silk fibre is 57.9 S m(-1). During 1000 bending measurements, the conductivity was stable and showed negligible variation. The G/S film has a sheet resistivity of 90 Ω □(-1) with a porous and hierarchical structure. The spiky Pt nanosphere decorated G/S film was directly used as a H₂O₂ electrode with a sensitivity of 0.56 mA mM(-1) cm(-2), a linear range of 0-2.5 mM and an ultralow detection limit of 0.2 μM (S/N = 3). A glucose biosensor electrode was further fabricated by enzyme immobilization. The results show a sensitivity of 150.8 μA mM(-1) cm(-2) and a low detection limit of 1 μM (S/N = 3) for glucose detection. The strategy of coating graphene sheets on a silk fibre surface provides a new approach for developing electrically conductive biomaterials, tissue engineering scaffolds, bendable electrodes, and wearable biomedical devices. PMID:24615460

  18. Electrochemical Properties of Graphene Oxide/Resol Composites as Electrode Materials for Supercapacitor Applications.

    PubMed

    Park, Geon Woo; Jeon, Sang Kwon; Yang, Jin Yong; Choi, Sung Dae; Kim, Geon Joong

    2016-05-01

    RGO/Resol carbon composites were prepared from a mixture of reduced GO and a low-molecular-weight phenolic resin (Resol) solution. The effects of the calcination temperature, amount of Resol added and KOH treatment on the electrochemical performance of the RGO/Resol composites were investigated. The physical and electrochemical properties of the composite materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer, Emmett and Teller (BET) surface areas measurements, and cyclic voltammetry (CV). The relationships between their physical properties and their electrochemical performance were examined for use as super-capacitors (SCs). The RGO/Resol composite calcined at 400 degrees C after the KOH loading showed dramatically improved electrochemical properties, showing a high BET surface and capacitance of 2190 m2/g and 220 F/g, respectively. The RGO/Resol composites calcined after the KOH treatment showed much better capacitor performance than those treated only thermally at the same temperature without KOH impregnation. The fabrication of high surface electrodes was essential for improving the SCs properties. PMID:27483752

  19. Nickel sulfide/graphene/carbon nanotube composites as electrode material for the supercapacitor application in the sea flashing signal system

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  20. Fabrication and application of flexible graphene silk composite film electrodes decorated with spiky Pt nanospheres

    NASA Astrophysics Data System (ADS)

    Liang, Bo; Fang, Lu; Hu, Yichuan; Yang, Guang; Zhu, Qin; Ye, Xuesong

    2014-03-01

    A free-standing graphene silk composite (G/S) film was fabricated via vacuum filtration of a mixed suspension of graphene oxide and silk fibres, followed by chemical reduction. Spiky structured Pt nanospheres were grown on the film substrate by cyclic voltammetry electrodeposition. The electrical and mechanical performance of a single graphene coated silk fibre was investigated. The conductivity of a single graphene coated silk fibre is 57.9 S m-1. During 1000 bending measurements, the conductivity was stable and showed negligible variation. The G/S film has a sheet resistivity of 90 Ω □-1 with a porous and hierarchical structure. The spiky Pt nanosphere decorated G/S film was directly used as a H2O2 electrode with a sensitivity of 0.56 mA mM-1 cm-2, a linear range of 0-2.5 mM and an ultralow detection limit of 0.2 μM (S/N = 3). A glucose biosensor electrode was further fabricated by enzyme immobilization. The results show a sensitivity of 150.8 μA mM-1 cm-2 and a low detection limit of 1 μM (S/N = 3) for glucose detection. The strategy of coating graphene sheets on a silk fibre surface provides a new approach for developing electrically conductive biomaterials, tissue engineering scaffolds, bendable electrodes, and wearable biomedical devices.A free-standing graphene silk composite (G/S) film was fabricated via vacuum filtration of a mixed suspension of graphene oxide and silk fibres, followed by chemical reduction. Spiky structured Pt nanospheres were grown on the film substrate by cyclic voltammetry electrodeposition. The electrical and mechanical performance of a single graphene coated silk fibre was investigated. The conductivity of a single graphene coated silk fibre is 57.9 S m-1. During 1000 bending measurements, the conductivity was stable and showed negligible variation. The G/S film has a sheet resistivity of 90 Ω □-1 with a porous and hierarchical structure. The spiky Pt nanosphere decorated G/S film was directly used as a H2O2 electrode with a

  1. Electrodes for microfluidic applications

    DOEpatents

    Crocker, Robert W.; Harnett, Cindy K.; Rognlien, Judith L.

    2006-08-22

    An electrode device for high pressure applications. These electrodes, designed to withstand pressure of greater than 10,000 psi, are adapted for use in microfluidic devices that employ electrokinetic or electrophoretic flow. The electrode is composed, generally, of an outer electrically insulating tubular body having a porous ceramic frit material disposed in one end of the outer body. The pores of the porous ceramic material are filled with an ion conductive polymer resin. A conductive material situated on the upper surface of the porous ceramic frit material and, thus isolated from direct contact with the electrolyte, forms a gas diffusion electrode. A metal current collector, in contact with the gas diffusion electrode, provides connection to a voltage source.

  2. Composite electrodes for electrochemical supercapacitors.

    PubMed

    Li, Jun; Yang, Quanmin; Zhitomirsky, Igor

    2010-01-01

    Manganese dioxide nanofibers with length ranged from 0.1 to 1 μm and a diameter of about 4-6 nm were prepared by a chemical precipitation method. Composite electrodes for electrochemical supercapacitors were fabricated by impregnation of the manganese dioxide nanofibers and multiwalled carbon nanotubes (MWCNT) into porous Ni plaque current collectors. Obtained composite electrodes, containing 85% of manganese dioxide and 15 mass% of MWCNT, as a conductive additive, with total mass loading of 7-15 mg cm-2, showed a capacitive behavior in 0.5-M Na2SO4 solutions. The decrease in stirring time during precipitation of the nanofibers resulted in reduced agglomeration and higher specific capacitance (SC). The highest SC of 185 F g-1 was obtained at a scan rate of 2 mV s-1 for mass loading of 7 mg cm-2. The SC decreased with increasing scan rate and increasing electrode mass. PMID:20672101

  3. Composite Electrodes for Electrochemical Supercapacitors

    PubMed Central

    2010-01-01

    Manganese dioxide nanofibers with length ranged from 0.1 to 1 μm and a diameter of about 4–6 nm were prepared by a chemical precipitation method. Composite electrodes for electrochemical supercapacitors were fabricated by impregnation of the manganese dioxide nanofibers and multiwalled carbon nanotubes (MWCNT) into porous Ni plaque current collectors. Obtained composite electrodes, containing 85% of manganese dioxide and 15 mass% of MWCNT, as a conductive additive, with total mass loading of 7–15 mg cm−2, showed a capacitive behavior in 0.5-M Na2SO4 solutions. The decrease in stirring time during precipitation of the nanofibers resulted in reduced agglomeration and higher specific capacitance (SC). The highest SC of 185 F g−1 was obtained at a scan rate of 2 mV s−1 for mass loading of 7 mg cm−2. The SC decreased with increasing scan rate and increasing electrode mass. PMID:20672101

  4. Composite Electrodes for Electrochemical Supercapacitors

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

    Manganese dioxide nanofibers with length ranged from 0.1 to 1 μm and a diameter of about 4-6 nm were prepared by a chemical precipitation method. Composite electrodes for electrochemical supercapacitors were fabricated by impregnation of the manganese dioxide nanofibers and multiwalled carbon nanotubes (MWCNT) into porous Ni plaque current collectors. Obtained composite electrodes, containing 85% of manganese dioxide and 15 mass% of MWCNT, as a conductive additive, with total mass loading of 7-15 mg cm-2, showed a capacitive behavior in 0.5-M Na2SO4 solutions. The decrease in stirring time during precipitation of the nanofibers resulted in reduced agglomeration and higher specific capacitance (SC). The highest SC of 185 F g-1 was obtained at a scan rate of 2 mV s-1 for mass loading of 7 mg cm-2. The SC decreased with increasing scan rate and increasing electrode mass.

  5. Water based, solution-processable, transparent and flexible graphene oxide composite as electrodes in organic solar cell application

    NASA Astrophysics Data System (ADS)

    Lima, L. F.; Matos, C. F.; Gonçalves, L. C.; Salvatierra, R. V.; Cava, C. E.; Zarbin, A. J. G.; Roman, L. S.

    2016-03-01

    In this work we propose an easy method to achieve a conductive, transparent and flexible graphene oxide (GO)-based composite thin film from an aqueous dispersion. We investigated the blend ratio between GO and the conjugated polymer poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) by comparing the thin film optical transmittance, sheet resistance, morphology and mechanical stability. It was found that reasonable values of transmittance and resistivity coupled with its excellent flexibility - the conductivity remains almost the same even after 1000 bends cycles - make this composite very attracting for flexible optoelectronic applications. Thus, these films were used as transparent electrodes in a bilayer structured organic solar cell and the device architecture PET/GO:PEDOT/F8T2/C60/Al could reach a power conversion efficiency around 1.10%. This result presents a better performance compared with pristine PEDOT produced with similar parameters.

  6. Capacitor with a composite carbon foam electrode

    DOEpatents

    Mayer, S.T.; Pekala, R.W.; Kaschmitter, J.L.

    1999-04-27

    Carbon aerogels used as a binder for granularized materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid particles being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivity and power to system energy. 1 fig.

  7. Capacitor with a composite carbon foam electrode

    DOEpatents

    Mayer, Steven T.; Pekala, Richard W.; Kaschmitter, James L.

    1999-01-01

    Carbon aerogels used as a binder for granularized materials, including other forms of carbon and metal additives, are cast onto carbon or metal fiber substrates to form composite carbon thin film sheets. The thin film sheets are utilized in electrochemical energy storage applications, such as electrochemical double layer capacitors (aerocapacitors), lithium based battery insertion electrodes, fuel cell electrodes, and electrocapacitive deionization electrodes. The composite carbon foam may be formed by prior known processes, but with the solid partides being added during the liquid phase of the process, i.e. prior to gelation. The other forms of carbon may include carbon microspheres, carbon powder, carbon aerogel powder or particles, graphite carbons. Metal and/or carbon fibers may be added for increased conductivity. The choice of materials and fibers will depend on the electrolyte used and the relative trade off of system resistivity and power to system energy.

  8. Freestanding nanocellulose-composite fibre reinforced 3D polypyrrole electrodes for energy storage applications

    NASA Astrophysics Data System (ADS)

    Wang, Zhaohui; Tammela, Petter; Zhang, Peng; Huo, Jinxing; Ericson, Fredric; Strømme, Maria; Nyholm, Leif

    2014-10-01

    It is demonstrated that 3D nanostructured polypyrrole (3D PPy) nanocomposites can be reinforced with PPy covered nanocellulose (PPy@nanocellulose) fibres to yield freestanding, mechanically strong and porosity optimised electrodes with large surface areas. Such PPy@nanocellulose reinforced 3D PPy materials can be employed as free-standing paper-like electrodes in symmetric energy storage devices exhibiting cell capacitances of 46 F g-1, corresponding to specific electrode capacitances of up to ~185 F g-1 based on the weight of the electrode, and 5.5 F cm-2 at a current density of 2 mA cm-2. After 3000 charge/discharge cycles at 30 mA cm-2, the reinforced 3D PPy electrode material also showed a cell capacitance corresponding to 92% of that initially obtained. The present findings open up new possibilities for the fabrication of high performance, low-cost and environmentally friendly energy-storage devices based on nanostructured paper-like materials.It is demonstrated that 3D nanostructured polypyrrole (3D PPy) nanocomposites can be reinforced with PPy covered nanocellulose (PPy@nanocellulose) fibres to yield freestanding, mechanically strong and porosity optimised electrodes with large surface areas. Such PPy@nanocellulose reinforced 3D PPy materials can be employed as free-standing paper-like electrodes in symmetric energy storage devices exhibiting cell capacitances of 46 F g-1, corresponding to specific electrode capacitances of up to ~185 F g-1 based on the weight of the electrode, and 5.5 F cm-2 at a current density of 2 mA cm-2. After 3000 charge/discharge cycles at 30 mA cm-2, the reinforced 3D PPy electrode material also showed a cell capacitance corresponding to 92% of that initially obtained. The present findings open up new possibilities for the fabrication of high performance, low-cost and environmentally friendly energy-storage devices based on nanostructured paper-like materials. Electronic supplementary information (ESI) available. See DOI: 10.1039/c

  9. Graphene decorated with MoS2 nanosheets: a synergetic energy storage composite electrode for supercapacitor applications.

    PubMed

    Thangappan, R; Kalaiselvam, S; Elayaperumal, A; Jayavel, R; Arivanandhan, M; Karthikeyan, R; Hayakawa, Y

    2016-02-14

    The two-dimensional (2D) transition metal dichalcogenide nanosheet-carbon composite is an attractive material for energy storage because of its high Faradaic activity, unique nanoconstruction and electronic properties. In this work, a facile one step preparation of a molybdenum disulfide (MoS2) nanosheet-graphene (MoS2/G) composite with the in situ reduction of graphene oxide is reported. The structure, morphology and composition of the pure MoS2 and composites were comparatively analyzed by various characterization techniques. The electrochemical performance of the pure MoS2, graphene oxide and the MoS2/G composite electrode materials was evaluated by cyclic voltammogram, galvanostatic charge-discharge and electrochemical impedance spectroscopy. The MoS2/G composite showed a higher specific capacitance (270 F g(-1) at a current density of 0.1 A g(-1)) compared to the pure MoS2 (162 F g(-1)) in a neutral aqueous electrolyte. Moreover, the energy density of the composite electrode is also higher (12.5 Wh kg(-1)) with a high power density (2500 W kg(-1)) compared to the pure MoS2. In addition, the MoS2/G composite electrode showed excellent cyclic stability even after 1000 cycles. The enhancement in specific capacitance, excellent cyclic stability and high energy density of the composite electrode are mainly due to the interconnected conductive network of the composite as well as the synergetic effect of the pure MoS2 and graphene. The experimental results demonstrated that the MoS2/G composite is a promising electrode material for high-performance supercapacitors. PMID:26732466

  10. Aluminum-carbon composite electrode

    DOEpatents

    Farahmandi, C.J.; Dispennette, J.M.

    1998-07-07

    A high performance double layer capacitor having an electric double layer formed in the interface between activated carbon and an electrolyte is disclosed. The high performance double layer capacitor includes a pair of aluminum impregnated carbon composite electrodes having an evenly distributed and continuous path of aluminum impregnated within an activated carbon fiber preform saturated with a high performance electrolytic solution. The high performance double layer capacitor is capable of delivering at least 5 Wh/kg of useful energy at power ratings of at least 600 W/kg. 3 figs.

  11. Aluminum-carbon composite electrode

    DOEpatents

    Farahmandi, C. Joseph; Dispennette, John M.

    1998-07-07

    A high performance double layer capacitor having an electric double layer formed in the interface between activated carbon and an electrolyte is disclosed. The high performance double layer capacitor includes a pair of aluminum impregnated carbon composite electrodes having an evenly distributed and continuous path of aluminum impregnated within an activated carbon fiber preform saturated with a high performance electrolytic solution. The high performance double layer capacitor is capable of delivering at least 5 Wh/kg of useful energy at power ratings of at least 600 W/kg.

  12. Transparent conductive multiwall carbon nanotubes-polymer composite for electrode applications.

    PubMed

    Nayak, Sasmita; Behura, Sanjay Kumar; Bhattacharjee, Sarama; Singh, Bimal P; Jani, Omkar; Mukhopadhyay, Indrajit

    2014-04-01

    Disperse Multiwall carbon nanotubes (MWCNTs) are incorporated aqueous N-hydroxy methyl acrylamide, which is subjected to crosslinking to develop a transparent conductive composite free standing film. The effects of the concentration of MWCNTs and temperature on optical and electrical properties of nano-composites are investigated. Interestingly, only 0.06 mg/ml of MWCNTs is sufficient to reach the percolation threshold (Phi) for transition in electrical conductivity up to 10(-4) S/cm, with a visible transmittance over 85%, which is well above the reported for such a low level of MWCNTs loading. The electrical conductivity of the composite was measured at 120 degrees C. It has been observed that electrical conductivity increases significantly with the increase in temperature, signifying the semiconducting nature of nano-composites. Finally, current-voltage (I-V) characteristics show liner behaviour, confirms Ohmic nature of nano-composites and metal contact. PMID:24734695

  13. Impedance spectroscopic analysis of composite electrode from activated carbon/conductive materials/ruthenium oxide for supercapacitor applications

    NASA Astrophysics Data System (ADS)

    Taer, E.; Deraman, M.; Talib, I. A.; Awitdrus, Farma, R.; Ishak, M. M.; Omar, R.; Dolah, B. N. M.; Basri, N. H.; Othman, M. A. R.; Kanwal, S.

    2015-04-01

    Activated carbon powders (ACP) were produced from the KOH treated pre-carbonized rubber wood sawdust. Different conductive materials (graphite, carbon black and carbon nanotubes (CNTs)) were added with a binder (polivinylidene fluoride (PVDF)) into ACP to improve the supercapacitive performance of the activated carbon (AC) electrodes. Symmetric supercapacitor cells, fabricated using these AC electrodes and 1 molar H2SO4 electrolyte, were analyzed using a standard electrochemical impedance spectroscopy technique. The addition of graphite, carbon black and CNTs was found effective in reducing the cell resistance from 165 to 68, 23 and 49 Ohm respectively, and increasing the specific capacitance of the AC electrodes from 3 to 7, 17, 32 F g-1 respectively. Since the addition of CNTs can produce the highest specific capacitance, CNTs were chosen as a conductive material to produce AC composite electrodes that were added with 2.5 %, 5 % and 10 % (by weight) electro-active material namely ruthenium oxide; PVDF binder and CNTs contents were kept at 5 % by weight in each AC composite produced. The highest specific capacitance of the cells obtained in this study was 86 F g-1, i.e. for the cell with the resistance of 15 Ohm and composite electrode consists of 5 % ruthenium oxide.

  14. Impedance spectroscopic analysis of composite electrode from activated carbon/conductive materials/ruthenium oxide for supercapacitor applications

    SciTech Connect

    Taer, E.; Awitdrus,; Farma, R.; Deraman, M. Talib, I. A.; Ishak, M. M.; Omar, R.; Dolah, B. N. M.; Basri, N. H.; Othman, M. A. R.; Kanwal, S.

    2015-04-16

    Activated carbon powders (ACP) were produced from the KOH treated pre-carbonized rubber wood sawdust. Different conductive materials (graphite, carbon black and carbon nanotubes (CNTs)) were added with a binder (polivinylidene fluoride (PVDF)) into ACP to improve the supercapacitive performance of the activated carbon (AC) electrodes. Symmetric supercapacitor cells, fabricated using these AC electrodes and 1 molar H{sub 2}SO{sub 4} electrolyte, were analyzed using a standard electrochemical impedance spectroscopy technique. The addition of graphite, carbon black and CNTs was found effective in reducing the cell resistance from 165 to 68, 23 and 49 Ohm respectively, and increasing the specific capacitance of the AC electrodes from 3 to 7, 17, 32 F g{sup −1} respectively. Since the addition of CNTs can produce the highest specific capacitance, CNTs were chosen as a conductive material to produce AC composite electrodes that were added with 2.5 %, 5 % and 10 % (by weight) electro-active material namely ruthenium oxide; PVDF binder and CNTs contents were kept at 5 % by weight in each AC composite produced. The highest specific capacitance of the cells obtained in this study was 86 F g{sup −1}, i.e. for the cell with the resistance of 15 Ohm and composite electrode consists of 5 % ruthenium oxide.

  15. Multiscale simulation process and application to additives in porous composite battery electrodes

    NASA Astrophysics Data System (ADS)

    Wieser, Christian; Prill, Torben; Schladitz, Katja

    2015-03-01

    Structure-resolving simulation of porous materials in electrochemical cells such as fuel cells and lithium ion batteries allows for correlating electrical performance with material morphology. In lithium ion batteries characteristic length scales of active material particles and additives range several orders of magnitude. Hence, providing a computational mesh resolving all length scales is not reasonably feasible and requires alternative approaches. In the work presented here a virtual process to simulate lithium ion batteries by bridging the scales is introduced. Representative lithium ion battery electrode coatings comprised of μm-scale graphite particles as active material and a nm-scale carbon/polymeric binder mixture as an additive are imaged with synchrotron radiation computed tomography (SR-CT) and sequential focused ion beam/scanning electron microscopy (FIB/SEM), respectively. Applying novel image processing methodologies for the FIB/SEM images, data sets are binarized to provide a computational grid for calculating the effective mass transport properties of the electrolyte phase in the nanoporous additive. Afterwards, the homogenized additive is virtually added to the micropores of the binarized SR-CT data set representing the active particle structure, and the resulting electrode structure is assembled to a virtual half-cell for electrochemical microheterogeneous simulation. Preliminary battery performance simulations indicate non-negligible impact of the consideration of the additive.

  16. Fabrication of silver nanowires and metal oxide composite transparent electrodes and their application in UV light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Yan, Xingzhen; Ma, Jiangang; Xu, Haiyang; Wang, Chunliang; Liu, Yichun

    2016-08-01

    In this paper, we prepared the silver nanowires (AgNWs)/aluminum-doped zinc oxide (AZO) composite transparent conducting electrodes for n-ZnO/p-GaN heterojunction light emitting-diodes (LEDs) by drop casting AgNW networks and subsequent atomic layer deposition (ALD) of AZO at 150 °C. The contact resistances between AgNWs were dramatically reduced by pre-annealing in the vacuum chamber before the ALD of AZO. In this case, AZO works not only as the conformal passivation layer that protects AgNWs from oxidation, but also as the binding material that improves AgNWs adhesion to substrates. Due to the localized surface plasmons (LSPs) of the AgNWs resonant coupling with the ultraviolet (UV) light emission from the LEDs, a higher UV light extracting efficiency is achieved from LEDs with the AgNWs/AZO composite electrodes in comparison with the conventional AZO electrodes. Additionally, the antireflective nature of random AgNW networks in the composite electrodes caused a broad output light angular distribution, which could be of benefit to certain optoelectronic devices like LEDs and solar cells.

  17. Lithium-aluminum-magnesium electrode composition

    DOEpatents

    Melendres, Carlos A.; Siegel, Stanley

    1978-01-01

    A negative electrode composition is presented for use in a secondary, high-temperature electrochemical cell. The cell also includes a molten salt electrolyte of alkali metal halides or alkaline earth metal halides and a positive electrode including a chalcogen or a metal chalcogenide as the active electrode material. The negative electrode composition includes up to 50 atom percent lithium as the active electrode constituent and a magnesium-aluminum alloy as a structural matrix. Various binary and ternary intermetallic phases of lithium, magnesium, and aluminum are formed but the electrode composition in both its charged and discharged state remains substantially free of the alpha lithium-aluminum phase and exhibits good structural integrity.

  18. Nickel cobalt oxide nanowire-reduced graphite oxide composite material and its application for high performance supercapacitor electrode material.

    PubMed

    Wang, Xu; Yan, Chaoyi; Sumboja, Afriyanti; Lee, Pooi See

    2014-09-01

    In this paper, we report a facile synthesis method of mesoporous nickel cobalt oxide (NiCo2O4) nanowire-reduced graphite oxide (rGO) composite material by urea induced hydrolysis reaction, followed by sintering at 300 degrees C. P123 was used to stabilize the GO during synthesis, which resulted in a uniform coating of NiCo2O4 nanowire on rGO sheet. The growth mechanism of the composite material is discussed in detail. The NiCo2O4-rGO composite material showed an outstanding electrochemical performance of 873 F g(-1) at 0.5 A g(-1) and 512 F g(-1) at 40 A g(-1). This method provides a promising approach towards low cost and large scale production of supercapacitor electrode material. PMID:25924377

  19. Composite electrode for use in electrochemical cells

    DOEpatents

    Vanderborgh, N.E.; Huff, J.R.; Leddy, J.

    1987-10-16

    A porous composite electrode for use in electrochemical cells. The electrode has a first face and a second face defining a relatively thin section therebetween. The electrode is comprised of an ion conducting material, an electron conducting material, and an electrocatalyst. The volume concentration of the ion conducting material is greatest at the first face and is decreased across the section, while the volume concentration of the electron conducting material is greatest at the second face and decreases across the section of the electrode. Substantially all of the electrocatalyst is positioned within the electrode section in a relatively narrow zone where the rate of electron transport of the electrode is approximately equal to the rate of ion transport of the electrode. 4 figs., 1 tab.

  20. Composite electrode for use in electrochemical cells

    DOEpatents

    Vanderborgh, Nicholas E.; Huff, James R.; Leddy, Johna

    1989-01-01

    A porous composite electrode for use in electrochemical cells. The electrode has a first face and a second face defining a relatively thin section therebetween. The electrode is comprised of an ion conducting material, an electron conducting material, and an electrocatalyst. The volume concentration of the ion conducting material is greatest at the first face and is decreased across the section, while the volume concentration of the electron conducting material is greatest at the second face and decreases across the section of the electrode. Substantially all of the electrocatalyst is positioned within the electrode section in a relatively narrow zone where the rate of electron transport of the electrode is approximately equal to the rate of ion transport of the electrode.

  1. Composite electrode/electrolyte structure

    DOEpatents

    Visco, Steven J.; Jacobson, Craig P.; DeJonghe, Lutgard C.

    2004-01-27

    Provided is an electrode fabricated from highly electronically conductive materials such as metals, metal alloys, or electronically conductive ceramics. The electronic conductivity of the electrode substrate is maximized. Onto this electrode in the green state, a green ionic (e.g., electrolyte) film is deposited and the assembly is co-fired at a temperature suitable to fully densify the film while the substrate retains porosity. Subsequently, a catalytic material is added to the electrode structure by infiltration of a metal salt and subsequent low temperature firing. The invention allows for an electrode with high electronic conductivity and sufficient catalytic activity to achieve high power density in ionic (electrochemical) devices such as fuel cells and electrolytic gas separation systems.

  2. Metal nanowire-graphene composite transparent electrodes

    NASA Astrophysics Data System (ADS)

    Mankowski, Trent; Zhu, Zhaozhao; Balakrishnan, Kaushik; Shikoh, Ali Sehpar; Touati, Farid; Benammar, Mohieddine; Mansuripur, Masud; Falco, Charlies M.

    2014-10-01

    Silver nanowires with 40 nm diameter and copper nanowires with 150 nm diameter were synthesized using low-temperature routes, and deposited in combination with ultrathin graphene sheets for use as transparent conductors. A systematic and detailed analysis involving nature of capping agent for the metal nanowires, annealing of deposited films, and pre-treatment of substrates revealed critical conditions necessary for preparing high performance transparent conducting electrodes. The best electrodes show ~90% optical transmissivity and sheet resistance of ~10 Ω/□, already comparable to the best available transparent electrodes. The metal nanowire-graphene composite electrodes are therefore well suited for fabrication of opto-electronic and electronic devices.

  3. Composite substrate for bipolar electrodes

    DOEpatents

    Tekkanat, B.; Bolstad, J.J.

    1992-12-22

    Substrates for electrode systems, particularly those to be used for bipolar electrodes in zinc-bromine batteries, are disclosed. The substrates preferably include carbon-black as a conductive filler in a polymeric matrix, with reinforcing materials such as glass fibers. Warpage of the zinc-bromine electrodes which was experienced in the prior art and which was believed to be caused by physical expansion of the electrodes due to bromine absorption by the carbon-black, is substantially eliminated when new substrate fabrication techniques are employed. In the present invention, substrates are prepared using a lamination process known as glass mat reinforced thermoplastics technology or, in an alternate embodiment, the substrate is made using a slurry process. 4 figs.

  4. Composite substrate for bipolar electrodes

    DOEpatents

    Tekkanat, Bora; Bolstad, James J.

    1992-12-22

    Substrates for electrode systems, particularly those to be used for bipolar electrodes in zinc-bromine batteries, are disclosed. The substrates preferably include carbon-black as a conductive filler in a polymeric matrix, with reinforcing materials such as glass fibers. Warpage of the zinc-bromine electrodes which was experienced in the prior art and which was believed to be caused by physical expansion of the electrodes due to bromine absorption by the carbon-black, is substantially eliminated when new substrate fabrication techniques are employed. In the pesent invention, substrates are prepared using a lamination process known as glass mat reinforced thermoplastics technology or, in an alternate embodiment, the substrate is made using a slurry process.

  5. Lithium-aluminum-iron electrode composition

    DOEpatents

    Kaun, Thomas D.

    1979-01-01

    A negative electrode composition is presented for use in a secondary electrochemical cell. The cell also includes an electrolyte with lithium ions such as a molten salt of alkali metal halides or alkaline earth metal halides that can be used in high-temperature cells. The cell's positive electrode contains a a chalcogen or a metal chalcogenide as the active electrode material. The negative electrode composition includes up to 50 atom percent lithium as the active electrode constituent in an alloy of aluminum-iron. Various binary and ternary intermetallic phases of lithium, aluminum and iron are formed. The lithium within the intermetallic phase of Al.sub.5 Fe.sub.2 exhibits increased activity over that of lithium within a lithium-aluminum alloy to provide an increased cell potential of up to about 0.25 volt.

  6. Composite coating for electrochemical electrode and method

    SciTech Connect

    De Neufville, J.P.; Rajoria, D.; Ovshinsky, S.R.

    1987-11-17

    A coated electrode is described which is capable of electrochemically releasing an active species to a nonaqueous electrolyte in an electrochemically cell. It comprises: an electrode body comprising active species material; and a composite coating over the electrode body comprising a non-metallic, inorganic, ionically conductive active species layer forming a coating over the electrode body for reducing passivation of the electrode body. The active species layer comprises the active species material present in the electrode body, at least one electronegative element selected from the group consisting of fluorine, iodine, bromine, chlorine, sulfur, nitrogen and oxygen and at least one amphoteric element and a polymer layer over the inorganic layer for maintaining the mechanical integrity of the inorganic layer.

  7. Research on interdigitated electrodes piezoelectric fiber composites by FEM

    NASA Astrophysics Data System (ADS)

    Liu, Yonggang; Shen, Xing; Zhao, Dongbiao; Qiu, Jinhao

    2007-07-01

    Interdigitated electrodes(IDEs) piezoelectric fiber composites is one kind of new smart materials which can be used as actuators in many applications because of its unique properties such as high induced stain and easy integration on curved surface of the base structure. In this paper, basic theories about composite were introduced briefly firstly. Then Electrostatic Field of this special electrode was analyzed. Finally, Finite Element Method is employed to numerically research the influence of thickness and material constants of polymer around electrodes, volume ratio of fibers and dimension of electrodes on the composite's induced strain and stress. The results show that the actuating strain and stress of interdigitated electrodes piezoelectric fiber composites can be improved much by employing polymer having high dielectric constant or decreasing the thickness of the polymer around IDEs. In addition, much higher induced strain and stress can be got by decreasing period of IDEs or increasing width of IDEs and volume ratio of fibers among the composite. At last, the maximum strain (280μɛ) was got from the numeric model of optimized samples, which is very large considering composite is not pure PZT ceramics.

  8. Fabrication and characterization of TiO2-NTs based hollow carbon fibers/carbon film composite electrode with NiOx decorated for capacitive application

    NASA Astrophysics Data System (ADS)

    Wei, Kajia; Wang, Yi; Han, Weiqing; Li, Jiansheng; Sun, Xiuyun; Shen, Jinyou; Wang, Lianjun

    2016-06-01

    This work designs a novel structure of TiO2 nanotubes (TiO2-NTs) based hollow carbon nanofibers (HCFs)/carbon film (CF) composite electrode with NiOx decorated for capacitive deionization application. The TiO2-NTs array is obtained through anode oxidation method on the titanium substrate, while the HCFs/CF is synthesized by thermal decomposition of a mixture of C6H12O6 and Ni(CH3COO)2·4H2O inside the nanochannels and over the caps of TiO2-NTs array, then followed by carbonization and HNO3 activation. The nickel possesses multi-functional effects during the synthesis process as carbon catalyst (Ni(II)), molecule binder (NiTi) and pseudo-capacitance supplier (NiOx). FE-SEM, XRD, Raman spectroscopy and water contact angle measurement reveal a uniform carbon distribution, favorable nickel dispersion, high stability and ideal hydrophilicity for this structure. With the addition of C6H12O6 and Ni(Ac)2·4H2O controlled at 10% (wt) and 2% (wt), respectively, a composite electrode with specific capacitance of 244.9 F·g-1, high oxygen evolution potential of 2.15 V and low water contact angle of 41.77° is obtained as well as minimum polarization impedance and efficient capacitive ability, which exhibits promising applications for practical employment.

  9. Graphite-teflon composite bienzyme electrodes for the determination of cholesterol in reversed micelles. Application to food samples.

    PubMed

    Peña, N; Ruiz, G; Reviejo, A J; Pingarrón, J M

    2001-03-15

    A bienzyme amperometric composite biosensor for the determination of free and total cholesterol in food samples is reported. Cholesterol oxidase and horseradish peroxidase, together with potassium ferrocyanide as a mediator, are incorporated into a graphite-70% Teflon matrix. The compatibility of this biosensor design with predominantly nonaqueous media allows the use of reversed micelles as working medium. The reversed micelles are formed with ethyl acetate as continuous phase (in which cholesterol is soluble), a 4% final concentration of 0.05 mol L(-1) phosphate buffer solution, pH 7.4, as dispersed phase, and 0.1 mol L(-1) AOT as emulsifying agent. Studies on the repeatability of the amperometric response obtained at +0.10 V, with and without regeneration of the electrode surface by polishing, on the useful lifetime of one single biosensor and on the reproducibility in the fabrication of different pellets illustrate the robustness of the biosensor design. Determination of free and total cholesterol in food samples such as butter, lard, and egg yoke was carried out, and the obtained results were advantageously compared with those provided by using a commercial Boehringer test kit. PMID:11305650

  10. Synthesis, characterization and application of electrode materials

    SciTech Connect

    He, L.

    1995-07-07

    It has been known that significant advances in electrochemistry really depend on improvements in the sensitivity, selectivity, convenience, and/or economy of working electrodes, especially through the development of new working electrode materials. The advancement of solid state chemistry and materials science makes it possible to provide the materials which may be required as satisfactory electrode materials. The combination of solid state techniques with electrochemistry expands the applications of solid state materials and leads to the improvement of electrocatalysis. The study of Ru-Ti{sub 4}O{sub 7} and Pt-Ti{sub 4}O{sub 7} microelectrode arrays as introduced in paper 1 and paper 4, respectively, focuses on their synthesis and characterization. The synthesis is described by high temperature techniques for Ru or Pt microelectrode arrays within a conductive Ti{sub 4}O{sub 7} ceramic matrix. The characterization is based on the data obtained by x-ray diffractometry, scanning electron microscopy, voltammetry and amperometry. These microelectrode arrays show significant enhancement in current densities in comparison to solid Ru and Pt electrodes. Electrocatalysis at pyrochlore oxide Bi{sub 2}Ru{sub 2}O{sub 7.3} and Bi{sub 2}Ir{sub 2}O{sub 7} electrodes are described in paper 2 and paper 3, respectively. Details are reported for the synthesis and characterization of composite Bi{sub 2}Ru{sub 2}O{sub 7.3} electrodes. Voltammetric data are examined for evidence that oxidation can occur with transfer of oxygen to the oxidation products in the potential region corresponding to anodic discharge of H{sub 2}O with simultaneous evolution of O{sub 2}. Paper 3 includes electrocatalytic activities of composite Bi{sub 2}Ir{sub 2}O{sub 7} disk electrodes for the oxidation of I{sup -} and the reduction of IO{sub 3}{sup -}.

  11. Ionic polymer metal composites with polypyrrole-silver electrodes

    NASA Astrophysics Data System (ADS)

    Cellini, F.; Grillo, A.; Porfiri, M.

    2015-03-01

    Ionic polymer metal composites (IPMCs) are a class of soft active materials that are finding increasing application in robotics, environmental sensing, and energy harvesting. In this letter, we demonstrate the fabrication of IPMCs via in-situ photoinduced polymerization of polypyrrole-silver electrodes on an ionomeric membrane. The composition, morphology, and sheet resistance of the electrodes are extensively characterized through a range of experimental techniques. We experimentally investigate IPMC electrochemistry through electrochemical impedance spectroscopy, and we propose a modified Randle's model to interpret the impedance spectrum. Finally, we demonstrate in-air dynamic actuation and sensing and assess IPMC performance against more established fabrication methods. Given the simplicity of the process and the short time required for the formation of the electrodes, we envision the application of our technique in the development of a rapid prototyping technology for IPMCs.

  12. Metal Oxide/Graphene Composites for Supercapacitive Electrode Materials.

    PubMed

    Jeong, Gyoung Hwa; Baek, Seungmin; Lee, Seungyeol; Kim, Sang-Wook

    2016-04-01

    Graphene composites with metal or metal oxide nanoparticles have been extensively investigated owing to their potential applications in the fields of fuel cells, batteries, sensing, solar cells, and catalysis. Among them, much research has focused on supercapacitor applications and have come close to realization. Composites include monometal oxides of cobalt, nickel, manganese, and iron, as well as their binary and ternary oxides. In addition, their morphological control and hybrid systems of carbon nanotubes have also been investigated. This review presents the current trends in research on metal oxide/graphene composites for supercapacitors. Furthermore, methods are suggested to improve the properties of electrochemical capacitor electrodes. PMID:27061763

  13. Conductor-polymer composite electrode materials

    DOEpatents

    Ginley, D.S.; Kurtz, S.R.; Smyrl, W.H.; Zeigler, J.M.

    1984-06-13

    A conductive composite material useful as an electrode, comprises a conductor and an organic polymer which is reversibly electrochemically dopable to change its electrical conductivity. Said polymer continuously surrounds the conductor in intimate electrical contact therewith and is prepared by electrochemical growth on said conductor or by reaction of its corresponding monomer(s) on said conductor which has been pre-impregnated or pre-coated with an activator for said polymerization. Amount of the conductor is sufficient to render the resultant composite electrically conductive even when the polymer is in an undoped insulating state.

  14. Synthesis and characterization of a novel hybrid nano composite cation exchanger poly-o-toluidine Sn(IV) tungstate: Its analytical applications as ion-selective electrode

    NASA Astrophysics Data System (ADS)

    Khan, Asif Ali; Shaheen, Shakeeba

    2013-02-01

    A novel organic-inorganic nano composite cation exchanger poly-o-toluidine Sn(IV) tungstate has been synthesized by incorporation of a polymer material into inorganic precipitate. The material is a class of hybrid ion-exchanger with good ion-exchange properties, reproducibility, stability and good selectivity for heavy metals. The physico-chemical properties of this nano composite material were characterized by using XRD, TGA, FTIR, SEM and TEM. The ion-exchange capacity, pH titrations, elution behavior and chemical stability were also carried out to study ion-exchange properties of the material. Distribution studies for various metal ions revealed that the nano composite is highly selective for Cd(II). An ion-selective membrane electrode was fabricated using this material for the determination of Cd(II) ions in solutions. The analytical utility of this electrode was established by employing it as an indicator electrode in electrometric titrations.

  15. Evaluation of commercial lithium-ion cells based on composite positive electrode for plug-in hybrid electric vehicle applications. Part I: Initial characterizations

    SciTech Connect

    Matthieu Dubarry; Cyril Truchot; Mikael Cugnet; Bor Yann Liaw; Kevin Gering; Sergiy Sazhin; David Jamison; Christopher Michelbacher

    2011-12-01

    Evaluating commercial Li-ion batteries presents some unique benefits. One of them is to use cells made from established fabrication process and form factor, such as those offered by the 18650 cylindrical configuration, to provide a common platform to investigate and understand performance deficiency and aging mechanism of target chemistry. Such an approach shall afford us to derive relevant information without influence from processing or form factor variability that may skew our understanding on cell-level issues. A series of 1.9 Ah 18650 lithium ion cells developed by a commercial source using a composite positive electrode comprising (LiMn1/3Ni1/3Co1/3O2 + LiMn2O4) is being used as a platform for the investigation of certain key issues, particularly path-dependent aging and degradation in future plug-in hybrid electric vehicle (PHEV) applications, under the US Department of Energy's Applied Battery Research (ABR) program. Here we report in Part I the initial characterizations of the cell performance and Part II some aspects of cell degradation in 2C cycle aging. The initial characterizations, including cell-to-cell variability, are essential for life cycle performance characterization in the second part of the report when cell-aging phenomena are discussed. Due to the composite nature of the positive electrode, the features (or signature) derived from the incremental capacity (IC) of the cell appear rather complex. In this work, the method to index the observed IC peaks is discussed. Being able to index the IC signature in details is critical for analyzing and identifying degradation mechanism later in the cycle aging study.

  16. Evaluation of commercial lithium-ion cells based on composite positive electrode for plug-in hybrid electric vehicle applications. Part I: Initial characterizations

    NASA Astrophysics Data System (ADS)

    Dubarry, Matthieu; Truchot, Cyril; Cugnet, Mikaël; Liaw, Bor Yann; Gering, Kevin; Sazhin, Sergiy; Jamison, David; Michelbacher, Christopher

    Evaluating commercial Li-ion batteries presents some unique benefits. One of them is to use cells made from established fabrication process and form factor, such as those offered by the 18650 cylindrical configuration, to provide a common platform to investigate and understand performance deficiency and aging mechanism of target chemistry. Such an approach shall afford us to derive relevant information without influence from processing or form factor variability that may skew our understanding on cell-level issues. A series of 1.9 Ah 18650 lithium ion cells developed by a commercial source using a composite positive electrode comprising {LiMn 1/3Ni 1/3Co 1/3O 2 + LiMn 2O 4} is being used as a platform for the investigation of certain key issues, particularly path-dependent aging and degradation in future plug-in hybrid electric vehicle (PHEV) applications, under the US Department of Energy's Applied Battery Research (ABR) program. Here we report in Part I the initial characterizations of the cell performance and Part II some aspects of cell degradation in 2C cycle aging. The initial characterizations, including cell-to-cell variability, are essential for life cycle performance characterization in the second part of the report when cell-aging phenomena are discussed. Due to the composite nature of the positive electrode, the features (or signature) derived from the incremental capacity (IC) of the cell appear rather complex. In this work, the method to index the observed IC peaks is discussed. Being able to index the IC signature in details is critical for analyzing and identifying degradation mechanism later in the cycle aging study.

  17. [Functionalization of screen printed electrodes with organic-inorganic hybrid nano-composites for bio-sensing applications].

    PubMed

    Shumyantseva, V V; Bulko, T V; Kuzikov, A V; Khan, R; Archakov, A I

    2015-01-01

    New types of organic-inorganic hybrid nanocomposites based on nanosized Titanium (IV) oxide TiO2 (<100 nm particle size) and carbon nanotubes (CNT, outer diameter 10-15 nm, inner diamentre 2-6 nm, length 0.1-10 µm) and phosphatidilcholine were elaborated for improvement of analytical characteristics of screen printed electrodes. These nanomaterials were employed as an interface for the immobilization of skeletal myoglobin. Electrochemical behavior of myoglobin on such interfaces was characterized with cyclic voltammetry (CV) and square wave voltammetry (SWV). Direct unmediated electron transfer between myoglobin and electrodes modified with organic-inorganic hybrid nanocomposites was registered. TiO2 film and CNT film are biocompartible nanomaterials for myoglobin as was demonstrated with UV-Vis spectra. The midpoint potential of Fe3+/Fe2+ pair of myoglobin corresponded to Е1/2=-0,263 V for CNT film, and Е1/2=-0,468 V for TiO2 nanocomposite (vs. Ag/AgCl reference electrode). PMID:26350738

  18. Synthesis and characterization of α-MoO{sub 3} nanobelt composite positive electrode materials for lithium battery application

    SciTech Connect

    Nadimicherla, Reddeppa; Chen, Wen; Guo, Xin

    2015-06-15

    Graphical abstract: (a) TEM image of MoO{sub 3}/PEO nanobelts composite, (b) CV curves of MoO{sub 3}/PEO nanobelts composite. - Highlights: • α-MoO{sub 3} and PEO surfactant MoO{sub 3} nanobelts were synthesized by solvothermal method. • The capacity retention of 12.5 wt% PEO surfactant MoO{sub 3} nanobelts is 88.78%. • The specific capacity of 12.5 wt% PEO surfactant MoO{sub 3} nanobelts is 352 mAh g{sup −1}. • MoO{sub 3}/PEO nanobelts composite material demonstrates good cycling stability as cathode. - Abstract: α-MoO{sub 3} and PEO surfactant MoO{sub 3} nanobelts were synthesized by a solvothermal method. The morphology and nanostructure of samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Bare α-MoO{sub 3} and 12.5 wt% PEO surfactant MoO{sub 3} nanobelts have an initial specific capacities of 279 and 352 mAh g{sup −1}, respectively, at constant current density 30 mA g{sup −1} with potential range of 1.5–4.0 V vs. Li/Li{sup +}. While MoO{sub 3} is modified by the intercalation of PEO, it is effectively shielded against electrostatic interaction between the MoO{sub 3} interlayer and Li{sup +} ions. We reported positive material, a nanocomposite of MoO{sub 3} coated with polyethylene oxide. It presents good cycling stability due to existence of the conductive and protective polyethylene oxide coating and the nanobelt morphology of MoO{sub 3}. The polyethylene oxide acts as a conducting matrix, a binder and an active material, as well as a volume change buffer agent, which holds the MoO{sub 3} particles in place during the discharge cycles. The cyclic voltammograms of the 12.5 wt% PEO surfactant MoO{sub 3} nanobelt composite displayed better cyclic performance compared with pure MoO{sub 3} nanobelts. The specific capacity of the pure MoO{sub 3} nanobelts and 12.5 wt% PEO surfactant MoO{sub 3

  19. Novel lead-graphene and lead-graphite metallic composite materials for possible applications as positive electrode grid in lead-acid battery

    NASA Astrophysics Data System (ADS)

    Yolshina, L. A.; Yolshina, V. A.; Yolshin, A. N.; Plaksin, S. V.

    2015-03-01

    Novel lead-graphene and lead-graphite metallic composites which melt at temperature of the melting point of lead were investigated as possible positive current collectors for lead acid batteries in sulfuric acid solution. Scanning electron microscopy, Raman spectroscopy, difference scanning calorimetry, cyclic voltammetry and prolonged corrosion tests were employed to characterize the effect of the newly proposed lead-carbon metallic composites on the structure and electrochemical properties of positive grid material. Both lead-graphene and lead-graphite metallic composite materials show the similar electrochemical characteristics to metallic lead in the voltage range where the positive electrodes of lead acid batteries operate. It has been shown that carbon both as graphene and graphite does not participate in the electrochemical process but improve corrosion and electrochemical characteristics of both metallic composite materials. No products of interaction of lead with sulfuric acid were formed on the surface of graphene and graphite so as it was not found additional peaks of carbon discharge on voltammograms which could be attributed to the carbon. Graphene inclusions in lead prevent formation of leady oxide nanocrystals which deteriorate discharge characteristics of positive electrode of LAB. Both lead-graphene alloy and lead-graphite metallic composite proved excellent electrochemical and corrosion behavior and can be used as positive grids in lead acid batteries of new generation.

  20. Nanothorn electrodes for ionic polymer-metal composite artificial muscles.

    PubMed

    Palmre, Viljar; Pugal, David; Kim, Kwang J; Leang, Kam K; Asaka, Kinji; Aabloo, Alvo

    2014-01-01

    Ionic polymer-metal composites (IPMCs) have recently received tremendous interest as soft biomimetic actuators and sensors in various bioengineering and human affinity applications, such as artificial muscles and actuators, aquatic propulsors, robotic end-effectors, and active catheters. Main challenges in developing biomimetic actuators are the attainment of high strain and actuation force at low operating voltage. Here we first report a nanostructured electrode surface design for IPMC comprising platinum nanothorn assemblies with multiple sharp tips. The newly developed actuator with the nanostructured electrodes shows a new way to achieve highly enhanced electromechanical performance over existing flat-surfaced electrodes. We demonstrate that the formation and growth of the nanothorn assemblies at the electrode interface lead to a dramatic improvement (3- to 5-fold increase) in both actuation range and blocking force at low driving voltage (1-3 V). These advances are related to the highly capacitive properties of nanothorn assemblies, increasing significantly the charge transport during the actuation process. PMID:25146561

  1. Nanothorn electrodes for ionic polymer-metal composite artificial muscles

    PubMed Central

    Palmre, Viljar; Pugal, David; Kim, Kwang J.; Leang, Kam K.; Asaka, Kinji; Aabloo, Alvo

    2014-01-01

    Ionic polymer-metal composites (IPMCs) have recently received tremendous interest as soft biomimetic actuators and sensors in various bioengineering and human affinity applications, such as artificial muscles and actuators, aquatic propulsors, robotic end-effectors, and active catheters. Main challenges in developing biomimetic actuators are the attainment of high strain and actuation force at low operating voltage. Here we first report a nanostructured electrode surface design for IPMC comprising platinum nanothorn assemblies with multiple sharp tips. The newly developed actuator with the nanostructured electrodes shows a new way to achieve highly enhanced electromechanical performance over existing flat-surfaced electrodes. We demonstrate that the formation and growth of the nanothorn assemblies at the electrode interface lead to a dramatic improvement (3- to 5-fold increase) in both actuation range and blocking force at low driving voltage (1–3 V). These advances are related to the highly capacitive properties of nanothorn assemblies, increasing significantly the charge transport during the actuation process. PMID:25146561

  2. Skin contact electrodes for medical applications.

    PubMed

    Eggins, B R

    1993-04-01

    Skin contact electrodes require electrolyte gels between the skin and the electrode in order to ensure good electrical contact. The effect of different types of electrolyte gel on skin impedance was studied. The main types of gels used were wet gels, karaya-gum based hydrogels and synthetic copolymer-based hydrogels [2-acrylamide-2-methylpropanesulfonic acid-N,N'-methylenebis(acrylamide) copolymers]. The effect of variation in gel composition on the impedance of the skin was investigated. PMID:8388179

  3. Inert electrode composition having agent for controlling oxide growth on electrode made therefrom

    DOEpatents

    Ray, S.P.

    1986-04-15

    An improved inert electrode composition is suitable for use as an inert electrode in the production of metals such as aluminum by the electrolytic reduction of metal oxide or metal salt dissolved in a molten salt bath. The composition comprises one or more metal alloys and metal compounds which may include oxides of the metals comprising the alloy. The alloy and metal compounds are interwoven in a network which provides improved electrical conductivity and mechanical strength while preserving the level of chemical inertness necessary for such an electrode to function satisfactorily. The electrode composition further includes a metal compound dopant which will aid in controlling the thickness of a protective oxide layer on at least the bottom portion of an electrode made therefrom during use. 12 figs.

  4. Inert electrode composition having agent for controlling oxide growth on electrode made therefrom

    DOEpatents

    Ray, Siba P.

    1986-01-01

    An improved inert electrode composition is suitable for use as an inert electrode in the production of metals such as aluminum by the electrolytic reduction of metal oxide or metal salt dissolved in a molten salt bath. The composition comprises one or more metal alloys and metal compounds which may include oxides of the metals comprising the alloy. The alloy and metal compounds are interwoven in a network which provides improved electrical conductivity and mechanical strength while preserving the level of chemical inertness necessary for such an electrode to function satisfactorily. The electrode composition further includes a metal compound dopant which will aid in controlling the thickness of a protective oxide layer on at least the bottom portion of an electrode made therefrom during use.

  5. Compliant composite electrodes and large strain bistable actuation

    NASA Astrophysics Data System (ADS)

    Yun, Sungryul; Yu, Zhibin; Niu, Xiaofan; Hu, Weili; Li, Lu; Brochu, Paul; Pei, Qibing

    2012-04-01

    Dielectric elastomer actuators (DEA) and bistable electroactive polymers (BSEP) both require compliant electrodes with rubbery elasticity and high conductivity at large strains. Stretchable opto-electronic devices additionally require the compliant electrodes to be optically transparent. Many candidate materials have been investigated. We report a new approach to mechanically robust, stretchable compliant electrodes. A facile in-situ composite synthesis and transfer technique is employed, and the resulting composite electrodes retain the high surface conductivity of the original conductive network formed by nanowires or nanotubes, while exhibiting the mechanical flexibility of the matrix polymer. The composite electrodes have high transparency and low surface roughness useful for the fabrication of polymer thinfilm electronic devices. The new electrodes are suitable for high-strain actuation, as a complaint resistive heating element to administer the temperature of shape memory polymers, and as the charge injection electrodes for flexible/stretchable polymer light emitting diodes. Bistable electroactive polymers employing the composite electrodes can be actuated to large strains via heating-actuation-cooling cycles.

  6. Carbon nanotube/felt composite electrodes without polymer binders

    NASA Astrophysics Data System (ADS)

    Rosolen, J. Mauricio; Matsubara, E. Y.; Marchesin, Marcel S.; Lala, Stella M.; Montoro, L. A.; Tronto, S.

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

  7. Development and characterization of a new conducting carbon composite electrode.

    PubMed

    Barsan, Madalina M; Pinto, Edilson M; Florescu, Monica; Brett, Christopher M A

    2009-03-01

    A new conducting composite flexible material prepared from cellulose acetate (CA) polymer and graphite has been developed and used for the fabrication of electrodes, which were then characterized by cyclic voltammetry and electrochemical impedance spectroscopy. Scanning electron microscopy (SEM) was used to provide information concerning the morphology of the composite electrode surface. The potential window, background currents and capacitance were evaluated by cyclic voltammetry in the pH range from 4.6 to 8.2. The voltammetry of model electroactive species demonstrates a close to reversible electrochemical behaviour, under linear diffusion control. The electroactive area of the composite electrodes increases after appropriate electrode polishing and electrochemical pre-treatment. The electrodes were used as substrate for the electropolymerisation of the phenazine dye neutral red, for future use as redox mediator in electrochemical biosensors. The composite electrodes were also successfully used for the amperometric detection of ascorbate at 0.0 V vs. SCE, and applied to the measurement of ascorbate in Vitamin C tablets; the sensor exhibits high sensitivity and a low detection limit of 7.7 microM. Perspectives for use as a versatile, mechanically flexible and robust composite electrode of easily adaptable dimensions are indicated. PMID:19200481

  8. Transparent composite electrode for high-efficiency polymer LEDs

    NASA Astrophysics Data System (ADS)

    Li, Lu; Yu, Zhibin; Liang, Jiajie; Chang, Chia-Hao; Hu, Weili; Pei, Qibing

    2012-09-01

    Polymer composite electrodes based on silver nanowires or carbon nanotubes have been prepared with transparency and surface conductivity approaching those of ITO/glass and better than ITO/PET. The conductive surface has an average roughness less than 10 nm, better than ITO/glass. Depending on the polymer matrix selected, the composite electrodes can be made rigid, flexible like polycarbonate, or stretchable like a rubber. Various polymer light emitting diodes,light emitting electrochemical cells and polymer solar cells have been fabricated using the composite electrode as anode, exhibiting electroluminescent efficiencies generally higher than control devices fabricated on ITO/glass. These polymer light emitting devices are all highly flexible and can be bent to less than 3 mm radius without loss of performance. With further modification of the composite electrodes, we have also demonstrated stretchable OLEDs wherein the emissive area can be elongated by as much as 50%.

  9. Manganese oxide composite electrodes for lithium batteries

    DOEpatents

    Johnson, Christopher S.; Kang, Sun-Ho; Thackeray, Michael M.

    2009-12-22

    An activated electrode for a non-aqueous electrochemical cell is disclosed with a precursor thereof a lithium metal oxide with the formula xLi.sub.2MnO.sub.3.(1-x)LiMn.sub.2-yM.sub.yO.sub.4 for 0.5electrode and 0.ltoreq.y<1 in which the Li.sub.2MnO.sub.3 and LiMn.sub.2-yM.sub.yO.sub.4 components have layered and spinel-type structures, respectively, and in which M is one or more metal cations. The electrode is activated by removing lithia, or lithium and lithia, from the precursor. A cell and battery are also disclosed incorporating the disclosed positive electrode.

  10. Ionic Conduction in Lithium Ion Battery Composite Electrode Governs Cross-sectional Reaction Distribution

    PubMed Central

    Orikasa, Yuki; Gogyo, Yuma; Yamashige, Hisao; Katayama, Misaki; Chen, Kezheng; Mori, Takuya; Yamamoto, Kentaro; Masese, Titus; Inada, Yasuhiro; Ohta, Toshiaki; Siroma, Zyun; Kato, Shiro; Kinoshita, Hajime; Arai, Hajime; Ogumi, Zempachi; Uchimoto, Yoshiharu

    2016-01-01

    Composite electrodes containing active materials, carbon and binder are widely used in lithium-ion batteries. Since the electrode reaction occurs preferentially in regions with lower resistance, reaction distribution can be happened within composite electrodes. We investigate the relationship between the reaction distribution with depth direction and electronic/ionic conductivity in composite electrodes with changing electrode porosities. Two dimensional X-ray absorption spectroscopy shows that the reaction distribution is happened in lower porosity electrodes. Our developed 6-probe method can measure electronic/ionic conductivity in composite electrodes. The ionic conductivity is decreased for lower porosity electrodes, which governs the reaction distribution of composite electrodes and their performances. PMID:27193448

  11. Ionic Conduction in Lithium Ion Battery Composite Electrode Governs Cross-sectional Reaction Distribution

    NASA Astrophysics Data System (ADS)

    Orikasa, Yuki; Gogyo, Yuma; Yamashige, Hisao; Katayama, Misaki; Chen, Kezheng; Mori, Takuya; Yamamoto, Kentaro; Masese, Titus; Inada, Yasuhiro; Ohta, Toshiaki; Siroma, Zyun; Kato, Shiro; Kinoshita, Hajime; Arai, Hajime; Ogumi, Zempachi; Uchimoto, Yoshiharu

    2016-05-01

    Composite electrodes containing active materials, carbon and binder are widely used in lithium-ion batteries. Since the electrode reaction occurs preferentially in regions with lower resistance, reaction distribution can be happened within composite electrodes. We investigate the relationship between the reaction distribution with depth direction and electronic/ionic conductivity in composite electrodes with changing electrode porosities. Two dimensional X-ray absorption spectroscopy shows that the reaction distribution is happened in lower porosity electrodes. Our developed 6-probe method can measure electronic/ionic conductivity in composite electrodes. The ionic conductivity is decreased for lower porosity electrodes, which governs the reaction distribution of composite electrodes and their performances.

  12. Ionic Conduction in Lithium Ion Battery Composite Electrode Governs Cross-sectional Reaction Distribution.

    PubMed

    Orikasa, Yuki; Gogyo, Yuma; Yamashige, Hisao; Katayama, Misaki; Chen, Kezheng; Mori, Takuya; Yamamoto, Kentaro; Masese, Titus; Inada, Yasuhiro; Ohta, Toshiaki; Siroma, Zyun; Kato, Shiro; Kinoshita, Hajime; Arai, Hajime; Ogumi, Zempachi; Uchimoto, Yoshiharu

    2016-01-01

    Composite electrodes containing active materials, carbon and binder are widely used in lithium-ion batteries. Since the electrode reaction occurs preferentially in regions with lower resistance, reaction distribution can be happened within composite electrodes. We investigate the relationship between the reaction distribution with depth direction and electronic/ionic conductivity in composite electrodes with changing electrode porosities. Two dimensional X-ray absorption spectroscopy shows that the reaction distribution is happened in lower porosity electrodes. Our developed 6-probe method can measure electronic/ionic conductivity in composite electrodes. The ionic conductivity is decreased for lower porosity electrodes, which governs the reaction distribution of composite electrodes and their performances. PMID:27193448

  13. Amperometric determination of hydrazine at manganese hexacyanoferrate modified graphite-wax composite electrode.

    PubMed

    Jayasri, D; Narayanan, S Sriman

    2007-06-01

    Fabrication, characterization and application of a manganese hexacyanoferrate (MnHCF) modified graphite-wax composite electrode are described. The MnHCF mixed with graphite powder was dispersed into molten paraffin wax to yield a conductive composite, which was used as electrode material to construct a renewable three-dimensional MnHCF modified electrode. The characterization of the modified electrode has been studied by electrochemical techniques. The cyclic voltammogram of the MnHCF modified graphite-wax composite electrode prepared under optimum composition, showed a well-defined redox couple due to Fe(CN)(6)(4-)/Fe(CN)(6)(3-) system. The electrocatalytic oxidation of hydrazine by MnHCF modified graphite-wax composite electrode has been investigated in an attempt to develop a new sensor for its determination. It was found that the mediator catalyzed the oxidation of hydrazine. The electrocatalytic oxidation of hydrazine was also studied under hydrodynamic and chronoamperometric conditions. The anodic current increases linearly with increase in the concentration of hydrazine in the range of 3.33x10(-5)M to 8.18x10(-3)M. The detection limit was found to be 6.65x10(-6)M (S/N=3). The modified electrode can also be used for on-line detection of hydrazine. The proposed method has also been applied for the determination of hydrazine in photographic developer solution. PMID:17118545

  14. Density impact on performance of composite Si/graphite electrodes

    DOE PAGESBeta

    Dufek, Eric J.; Picker, Michael; Petkovic, Lucia M.

    2016-01-27

    The ability of alkali-substituted binders for composite Si and graphite negative electrodes to minimize capacity fade for lithium ion batteries is investigated. Polymer films and electrodes are described and characterized by FTIR following immersion in electrolyte (1:2 EC:DMC) for 24 h. FTIR analysis following electrode formation displayed similar alkali-ion dependent shifts in peak location suggesting that changes in the vibrational structure of the binder are maintained after electrode formation. The Si and graphite composite electrodes prepared using the alkali-substituted polyacrylates were also exposed to electrochemical cycling and it has been found that the performance of the Na-substituted binder is superiormore » to a comparable density K-substituted system. However, in comparing performance across many different electrode densities attention needs to be placed on making comparisons at similar densities, as low density electrodes tend to exhibit lower capacity fade over cycling. This is highlighted by a 6% difference between a low density K-substituted electrode and a high density Na-substituted sample. As a result, this low variance between the two systems makes it difficult to quickly make a direct evaluation of binder performance unless electrode density is tightly controlled.« less

  15. Polymer-graphite composite: a versatile use and throw plastic chip electrode.

    PubMed

    Perween, Mosarrat; Parmar, Dilip B; Bhadu, Gopala Ram; Srivastava, Divesh N

    2014-11-21

    We report an efficient plastic chip electrode (PCE) fabricated from a composite of graphite and poly(methyl methacrylate) by a simple solution casting method and promoted as an economically inexpensive, multipurpose disposable electrode for various applications. The TEM images of the filler (graphite) show that the material consists of single, as well as multi-layers. Thus, the self-standing and arid electrodes prepared were characterized for their material properties such as, microscopy (SEM and AFM), as well as thermal properties (TGA), mechanical (tensile strength) and electrical properties. A set of physical parameters were derived from these characterizations for sustainability of these electrodes in harsh off-laboratory conditions. The utility of these mechanically stable, bulk-conducting and high surface area electrodes were demonstrated in various well understood electrochemical protocols, such as cyclic voltammetry, stripping voltammetry, electropolymerization, electrowinning and amperometric sensing. The voltammetry data were compared with the data recorded on a conventional glassy carbon electrode. PMID:25248864

  16. Discussion on a percolating conducting network of a composite thin-film electrode (≤1 μm) for micro-solid oxide fuel cell application.

    PubMed

    Muller, Guillaume; Ringuedé, Armelle; Laberty-Robert, Christel

    2014-07-29

    Ni/Gd0.1Ce0.9O(2-δ) (Ni/GDC) and La0.6Sr0.4Fe0.8Co0.2O(3-δ)/Gd0.1Ce0.9O(2-δ) (LSCF/GDC) porous thin-film electrodes with thicknesses between 120 and 500 nm were synthesized through templated sol-gel chemistry coupled with the dip-coating process and heat treatment. The thin films consist of two interpenetrated networks made of pores and inorganic materials. The porous structure was composed of multi-scale pores with dimensions ranging from macro- to nanosize and with an oriented columnar structure. The dimension of the percolation network is discussed as a function of the chemical nature of the percolating components and the particle/thickness ratio. A three-dimensional percolation network is achieved in the LSCF/GDC composite, while a two-dimensional percolation network is observed for the Ni/GDC composite. This difference is related to the microstructure of the composite thin film. An anisotropic columnar structure is observed for Ni/GDC, while an isotropic structure is achieved for LSCF/GDC. PMID:24967944

  17. A Nanoporous Carbon/Exfoliated Graphite Composite For Supercapacitor Electrodes

    NASA Astrophysics Data System (ADS)

    Rosi, Memoria; Ekaputra, Muhamad P.; Iskandar, Ferry; Abdullah, Mikrajuddin; Khairurrijal

    2010-12-01

    Nanoporous carbon was prepared from coconut shells using a simple heating method. The nanoporous carbon is subjected to different treatments: without activation, activation with polyethylene glycol (PEG), and activation with sodium hydroxide (NaOH)-PEG. The exfoliated graphite was synthesized from graphite powder oxidized with zinc acetate (ZnAc) and intercalated with polyvinyl alcohol (PVA) and NaOH. A composite was made by mixing the nanoporous carbon with NaOH-PEG activation, the exfoliated graphite and a binder of PVA solution, grinding the mixture, and annealing it using ultrasonic bath for 1 hour. All of as-synthesized materials were characterized by employing a scanning electron microscope (SEM), a MATLAB's image processing toolbox, and an x-ray diffractometer (XRD). It was confirmed that the composite is crystalline with (002) and (004) orientations. In addition, it was also found that the composite has a high surface area, a high distribution of pore sizes less than 40 nm, and a high porosity (67%). Noting that the pore sizes less than 20 nm are significant for ionic species storage and those in the range of 20 to 40 nm are very accessible for ionic clusters mobility across the pores, the composite is a promising material for the application as supercapacitor electrodes.

  18. Manganese oxide composite electrodes for lithium batteries

    DOEpatents

    Thackeray, Michael M.; Johnson, Christopher S.; Li, Naichao

    2007-12-04

    An activated electrode for a non-aqueous electrochemical cell is disclosed with a precursor of a lithium metal oxide with the formula xLi.sub.2MnO.sub.3.(1-x)LiMn.sub.2-yM.sub.yO.sub.4 for 0electrode is activated by removing lithia, or lithium and lithia, from the precursor. A cell and battery are also disclosed incorporating the disclosed positive electrode.

  19. [Remediation of chromium (VI) contaminated soils using permeable reactive composite electrodes technology].

    PubMed

    Fu, Rong-Bing; Liu, Fang; Ma, Jin; Zhang, Chang-Bo; He, Guo-Fu

    2012-01-01

    Electrokinetic transport processes have been shown to have potential for the effective removal of heavy metals from soils. However, pH changes near the anode and cathode limit their widespread application in the remediation of contaminated soils. Permeable reactive composite electrodes (PRCE) were made by attaching reactive materials such as Fe(0) and zeolite to the electrodes, and the effects of the composite electrodes on pH control, chromium removal efficiency and Cr speciation changes were studied in the electrokinetic remediation process of Cr( VI) contaminated soil. Composite electrodes consisting of permeable reactive materials gave better pH control and Cr removal efficiency compared to traditional electrodes, and a Fe(0) + zeolite reactive layer in the anode exhibited the best performance compared to zeolite or Fe(0) alone. After 5 days of electrokinetic remediation with a DC voltage of 2 V x cm(-1), the Fe(0) + zeolite reactive layer lowered the pH fluctuation, maintained the soil pH in the range of 5.5 to 8.5, raised the Cr(VI) removal efficiency up to 97% in any soil section, produced lower Cr(III) residues, enhanced the amount of Cr retention up to 8 and 1.8 times respectively, and transformed 98% of the Cr(VI) into lower toxicity Cr(III). This study provides a theoretical basis for the exploitation of permeable reactive composite electrodes which are a practical option for future applications. PMID:22452223

  20. Platinum nanophase electro catalysts and composite electrodes for hydrogen production

    NASA Astrophysics Data System (ADS)

    Petrik, L. F.; Godongwana, Z. G.; Iwuoha, E. I.

    Nanophase Pt electro catalysts were prepared by impregnating a Pt salt containing solution upon a high surface area hexagonal mesoporous silica (HMS) matrix, which was then carbonized to varying degree by chemical vapour deposition of liquid petroleum gas (LPG). Thereafter the HMS Si matrix could be removed by chemical etching with NaOH to immediately form a Pt containing carbon analogue or ordered mesoporous carbon (OMC) with a porous structure similar to the parent HMS. Nanoparticles of Pt electro catalysts were thus successfully stabilized without agglomeration on both HMS and upon the porous HMS carbon analogue or OMC, which was graphitic in nature. The catalysts were electro active for the hydrogen evolution reaction and their activity compared favourable with an industry standard. Such nanophase Pt electro catalysts could be incorporated successfully in a composite electrode by sequential deposition, upon a suitable substrate and the catalysts in electrodes so formed proved to be stable and active under high-applied potential in high electrolyte environment for hydrogen production by electrolysis of water. This route to preparing a nanophase Pt OMC catalyst may be applicable to prepare active electro catalysts for polymer electrolyte fuel cells and solid polymer electrolyte electrolyzers.

  1. A new composite electrode architecture for energy storage devices

    NASA Technical Reports Server (NTRS)

    Ferro, Richard E.; Swain, Greg M.; Tatarchuk, B. J.

    1992-01-01

    The research objective is to determine how the electrode microstructure (architecture) affect the performance of the nickel hydroxide electrochemical system. It was found that microstructure and additional surface area makes a difference. The best architectures are the FIBREX/nickel and nickel fiber composite electrodes. The conditioning time for full utilization was greatly reduced. The accelerated increase in capacity vs. cycling appears to be a good indicator of the condition of the electrode/active material microstructure and morphology. Conformal deposition of the active material may be indicated and important. Also higher utilizations were obtained; greater than 80 pct. after less than 5 cycles and greater than 300 pct. after more than 5 cycles using nickel fiber composite electrode assuming a 1 electron transfer per equivalent.

  2. Polymeric metallic electrodes for rechargeable battery applications

    NASA Technical Reports Server (NTRS)

    Somoano, R.

    1982-01-01

    A review is presented on the status of plastic metal electrodes, emphasizing the use of polyacetylene as a prototype polymeric material. The electrochemical characteristics of polyacetylene are examined; and the potential use of this material, as well as other types of plastic metal electrodes, in batteries is evaluated. Several problem areas which must be solved before polyacetylene can be widely used in battery applications are discussed, including the problem of electrolyte stability, the problem that the depth of discharge and the energy density is limited by the metal-semiconductor transition, and also the poor electrochemical performance of impure material.

  3. Toward Uniformly Dispersed Battery Electrode Composite Materials: Characteristics and Performance.

    PubMed

    Kwon, Yo Han; Huie, Matthew M; Choi, Dalsu; Chang, Mincheol; Marschilok, Amy C; Takeuchi, Kenneth J; Takeuchi, Esther S; Reichmanis, Elsa

    2016-02-10

    Battery electrodes are complex mesoscale systems comprised of electroactive components, conductive additives, and binders. In this report, methods for processing electrodes with dispersion of the components are described. To investigate the degree of material dispersion, a spin-coating technique was adopted to provide a thin, uniform layer that enabled observation of the morphology. Distinct differences in the distribution profile of the electrode components arising from individual materials physical affinities were readily identified. Hansen solubility parameter (HSP) analysis revealed pertinent surface interactions associated with materials dispersivity. Further studies demonstrated that HSPs can provide an effective strategy to identify surface modification approaches for improved dispersions of battery electrode materials. Specifically, introduction of surfactantlike functionality such as oleic acid (OA) capping and P3HT-conjugated polymer wrapping on the surface of nanomaterials significantly enhanced material dispersity over the composite electrode. The approach to the surface treatment on the basis of HSP study can facilitate design of composite electrodes with uniformly dispersed morphology and may contribute to enhancing their electrical and electrochemical behaviors. The conductivity of the composites and their electrochemical performance was also characterized. The study illustrates the importance of considering electronic conductivity, electron transfer, and ion transport in the design of environments incorporating active nanomaterials. PMID:26765041

  4. Towards uniformly dispersed battery electrode composite materials: Characteristics and performance

    DOE PAGESBeta

    Yo Han Kwon; Takeuchi, Esther S.; Huie, Matthew M.; Choi, Dalsu; Chang, Mincheol; Marschilok, Amy C.; Takeuchi, Kenneth J.; Reichmanis, Elsa

    2016-01-14

    Battery electrodes are complex mesoscale systems comprised of electroactive components, conductive additives, and binders. In this report, methods for processing electrodes with dispersion of the components are described. To investigate the degree of material dispersion, a spin-coating technique was adopted to provide a thin, uniform layer that enabled observation of the morphology. Distinct differences in the distribution profile of the electrode components arising from individual materials physical affinities were readily identified. Hansen solubility parameter (HSP) analysis revealed pertinent surface interactions associated with materials dispersivity. Further studies demonstrated that HSPs can provide an effective strategy to identify surface modification approaches formore » improved dispersions of battery electrode materials. Specifically, introduction of surfactantlike functionality such as oleic acid (OA) capping and P3HT-conjugated polymer wrapping on the surface of nanomaterials significantly enhanced material dispersity over the composite electrode. The approach to the surface treatment on the basis of HSP study can facilitate design of composite electrodes with uniformly dispersed morphology and may contribute to enhancing their electrical and electrochemical behaviors. The conductivity of the composites and their electrochemical performance was also characterized. In conclusion, the study illustrates the importance of considering electronic conductivity, electron transfer, and ion transport in the design of environments incorporating active nanomaterials.« less

  5. Ionic polymer metal composites with nanoporous carbon electrodes

    NASA Astrophysics Data System (ADS)

    Palmre, Viljar; Brandell, Daniel; Mäeorg, Uno; Torop, Janno; Volobujeva, Olga; Punning, Andres; Johanson, Urmas; Aabloo, Alvo

    2010-04-01

    Ionic Polymer Metal Composites (IPMCs) are soft electroactive polymer materials that bend in response to the voltage stimulus (1 - 4 V). They can be used as actuators or sensors. In this paper, we introduce two new highly-porous carbon materials for assembling high specific area electrodes for IPMC actuators and compare their electromechanical performance with recently reported IPMCs based on RuO2 electrodes. We synthesize ionic liquid (Emi-Tf) actuators with either Carbide-Derived Carbon (CDC) (derived from TiC) or coconut shell based activated carbon electrodes. The carbon electrodes are applied onto ionic liquid-swollen Nafion membranes using the direct assembly process. Our results show that actuators assembled with CDC electrodes have the greatest peak-to-peak strain output, reaching up to 20.4 mɛ (equivalent to >2%) at a 2 V actuation signal, exceeding that of the RuO2 electrodes by more than 100%. The electrodes synthesized from TiC-derived carbon also revealed significantly higher maximum strain rate. The differences between the materials are discussed in terms of molecular interactions and mechanisms upon actuation in the different electrodes.

  6. Selective and sensitive determination of dopamine by composites of polypyrrole and graphene modified electrodes.

    PubMed

    Si, Peng; Chen, Hailan; Kannan, Palanisamy; Kim, Dong-Hwan

    2011-12-21

    A novel method is developed to fabricate the polypyrrole (PPy) and graphene thin films on electrodes by electrochemical polymerization of pyrrole with graphene oxide (GO) as a dopant, followed by electrochemical reduction of GO in the composite film. The composite of PPy and electrochemically reduced graphene oxide (eRGO)-modified electrode is highly sensitive and selective toward the detection of dopamine (DA) in the presence of high concentrations of ascorbic acid (AA) and uric acid (UA). The sensing performance of the PPy/eRGO-modified electrode is investigated by differential pulse voltammetry (DPV), revealing a linear range of 0.1-150 μM with a detection limit of 23 nM (S/N = 3). The practical application of the PPy/eRGO-modified electrode is successfully demonstrated for DA determination in human blood serum. PMID:22010122

  7. Electrical measuring while drilling with composite electrodes

    SciTech Connect

    Peppers, J.M.

    1986-04-22

    A method is described for transmitting data taken at the bottom of a well bore near the drill bit to the earth's surface through a large volume of the earth formation surrounding the well bore between the drill bit and the earth's surface. The method consists of: (a) generating electrical power within the drill pipe responsive to drilling fluids pumped through the drill pipe; (b) generating sequential bursts of a first AC voltage in digital sequence representing a digital information signal with use of such electrical power and with the digital being representative of a measured parameter occurring near the drill bit; (c) passing a first AC signal current impressed by the first AC voltage through a first electrode from the drilling string to be focussed outwardly and radially away from the well bore to form one path of initially horizontal current flow radially out through the drilling fluids and surrounding earth formation with the common path of the first AC current being the drill pipe; and (d) receiving and detecting a first AC signal potential resulting from the first AC signal current with a receiver/detection means connected to the drill pipe and to a receiver electrode located remote from the drilling string and electrically connected into the earth formation.

  8. Air electrode composition for solid oxide fuel cell

    DOEpatents

    Kuo, L.; Ruka, R.J.; Singhal, S.C.

    1999-08-03

    An air electrode composition for a solid oxide fuel cell is disclosed. The air electrode material is based on lanthanum manganite having a perovskite-like crystal structure ABO{sub 3}. The A-site of the air electrode composition comprises a mixed lanthanide in combination with rare earth and alkaline earth dopants. The B-site of the composition comprises Mn in combination with dopants such as Mg, Al, Cr and Ni. The mixed lanthanide comprises La, Ce, Pr and, optionally, Nd. The rare earth A-site dopants preferably comprise La, Nd or a combination thereof, while the alkaline earth A-site dopant preferably comprises Ca. The use of a mixed lanthanide substantially reduces raw material costs in comparison with compositions made from high purity lanthanum starting materials. The amount of the A-site and B-site dopants is controlled in order to provide an air electrode composition having a coefficient of thermal expansion which closely matches that of the other components of the solid oxide fuel cell. 3 figs.

  9. Air electrode composition for solid oxide fuel cell

    DOEpatents

    Kuo, Lewis; Ruka, Roswell J.; Singhal, Subhash C.

    1999-01-01

    An air electrode composition for a solid oxide fuel cell is disclosed. The air electrode material is based on lanthanum manganite having a perovskite-like crystal structure ABO.sub.3. The A-site of the air electrode composition comprises a mixed lanthanide in combination with rare earth and alkaline earth dopants. The B-site of the composition comprises Mn in combination with dopants such as Mg, Al, Cr and Ni. The mixed lanthanide comprises La, Ce, Pr and, optionally, Nd. The rare earth A-site dopants preferably comprise La, Nd or a combination thereof, while the alkaline earth A-site dopant preferably comprises Ca. The use of a mixed lanthanide substantially reduces raw material costs in comparison with compositions made from high purity lanthanum starting materials. The amount of the A-site and B-site dopants is controlled in order to provide an air electrode composition having a coefficient of thermal expansion which closely matches that of the other components of the solid oxide fuel cell.

  10. Processing of carbon composite paper as electrode for fuel cell

    NASA Astrophysics Data System (ADS)

    Mathur, R. B.; Maheshwari, Priyanka H.; Dhami, T. L.; Sharma, R. K.; Sharma, C. P.

    The porous carbon electrode in a fuel cell not only acts as an electrolyte and a catalyst support, but also allows the diffusion of hydrogen fuel through its fine porosity and serves as a current-carrying conductor. A suitable carbon paper electrode is developed and possesses the characteristics of high porosity, permeability and strength along with low electrical resistivity so that it can be effectively used in proton-exchange membrane and phosphoric acid fuel cells. The electrode is prepared through a combination of two important techniques, viz., paper-making technology by first forming a porous chopped carbon fibre preform, and composite technology using a thermosetting resin matrix. The study reveals an interdependence of one parameter on another and how judicious choice of the processing conditions are necessary to achieve the desired characteristics. The current-voltage performance of the electrode in a unit fuel cell matches that of a commercially-available material.

  11. Exfoliated graphite-ruthenium oxide composite electrodes for electrochemical supercapacitors

    NASA Astrophysics Data System (ADS)

    Mitra, Sagar; Lokesh, K. S.; Sampath, S.

    The performance of exfoliated graphite (EG)-ruthenium oxide (RuO x) composites as binderless electrodes is evaluated for electrochemical capacitors (ECs). A composite of EG-RuO x is prepared by a modified sol-gel process. The material is characterized using X-ray diffraction and microscopy. Electrochemical capacitors with the composite electrodes in the presence of aqueous sulfuric acid (H 2SO 4) electrolyte are evaluated using voltammetry, impedance and charge-discharge studies. Cyclic voltammetry reveals very stable current-voltage behaviour up to several thousands of cycles, as well as high specific capacitances, e.g., a few hundreds of farads per gram for the composite that contains 16.5 wt.% RuO x.

  12. Method for uniformly distributing carbon flakes in a positive electrode, the electrode made thereby and compositions

    DOEpatents

    Mrazek, Franklin C.; Smaga, John A.; Battles, James E.

    1983-01-01

    A positive electrode for a secondary electrochemical cell wherein an electrically conductive current collector is in electrical contact with a particulate mixture of gray cast iron and an alkali metal sulfide and an electrolyte including alkali metal halides or alkaline earth metal halides. Also present may be a transition metal sulfide and graphite flakes from the conversion of gray cast iron to iron sulfide. Also disclosed is a method of distributing carbon flakes in a cell wherein there is formed an electrochemical cell of a positive electrode structure of the type described and a suitable electrolyte and a second electrode containing a material capable of alloying with alkali metal ions. The cell is connected to a source of electrical potential to electrochemically convert gray cast iron to an iron sulfide and uniformly to distribute carbon flakes formerly in the gray cast iron throughout the positive electrode while forming an alkali metal alloy in the negative electrode. Also disclosed are compositions useful in preparing positive electrodes.

  13. Silver electrodes for reversible oxygen sensor applications

    NASA Astrophysics Data System (ADS)

    Kim, Taekyeong

    2015-09-01

    We report a single oxygen atomic sensor based on a scanning tunneling microscope break-junction (STM-BJ) technique by using silver electrodes at room temperature. The oxygen concentration was adjusted with argon gas in a glove box. An oxygen atom was inserted in the gap of the Ag electrodes after the Ag metal point contact had been ruptured during stretching of the Ag atomic junctions by moving a piezo. We successfully measured the conductance of a single oxygen atom by forming a series with the Ag contact, Ag-O-Ag bond. We found that the probability of Ag-O-Ag junction formation increased with increasing oxygen concentration. Furthermore, we observed that the peak height in the oxygen conductance histogram was changed reversibly depending on the oxygen concentration in a glove box. It confirms that our STM-BJ can be used for atomic sensor applications in the future.

  14. New reusable elastomer electrodes for assessing body composition

    NASA Astrophysics Data System (ADS)

    Moreno, M.-V.; Chaset, L.; Bittner, P. A.; Barthod, C.; Passard, M.

    2013-04-01

    The development of telemedicine requires finding solutions of reusable electrodes for use in patients' homes. The objective of this study is to evaluate the relevance of reusable elastomer electrodes for measuring body composition. We measured a population of healthy Caucasian (n = 17). A measurement was made with a reference device, the Xitron®, associated with AgCl Gel electrodes (Gel) and another measurement with a multifrequency impedancemeter Z-Metrix® associated with reusable elastomer electrodes (Elast). We obtained a low variability with an average error of repeatability of 0.39% for Re and 0.32% for Rinf. There is a non significantly difference (P T-test > 0.1) about 200 ml between extracellular water Ve measured with Gel and Elast in supine and in standing position. For total body water Vt, we note a non significantly difference (P T-test > 0.1) about 100 ml and 2.2 1 respectively in supine and standing position. The results give low dispersion, with R2 superior to 0.90, with a 1.5% maximal error between Gel and Elast on Ve in standing position. It looks possible, taking a few precautions, using elastomer electrodes for assessing body composition.

  15. Critical current density in railgrun accelerators with composite electrodes

    SciTech Connect

    Stankevich, S.V.; Shvetsov, G.A.

    1995-11-01

    The present paper is intended to study the possibilities of increasing the critical current density in railgun accelerators using composite electrodes of various structure. Before proceeding to the analysis this way, it should be noted that the requirements for materials selected for the rails go beyond the values of the current density. In real practice account should be taken of the technological problems concerned with the production of the electrodes, as well as of those concerned with the railgun performance, including the multishot life.

  16. Fully solution-processed transparent electrodes based on silver nanowire composites for perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Kim, Areum; Lee, Hongseuk; Kwon, Hyeok-Chan; Jung, Hyun Suk; Park, Nam-Gyu; Jeong, Sunho; Moon, Jooho

    2016-03-01

    We report all-solution-processed transparent conductive electrodes based on Ag nanowire (AgNW)-embedded metal oxide composite films for application in organometal halide perovskite solar cells. To address the thermal instability of Ag nanowires, we used combustive sol-gel derived thin films to construct ZnO/ITO/AgNW/ITO composite structures. The resulting composite configuration effectively prevented the AgNWs from undergoing undesirable side-reactions with halogen ions present in the perovskite precursor solutions that significantly deteriorate the optoelectrical properties of Ag nanowires in transparent conductive films. AgNW-based composite electrodes had a transmittance of ~80% at 550 nm and sheet resistance of 18 Ω sq-1. Perovskite solar cells fabricated using a fully solution-processed transparent conductive electrode, Au/spiro-OMeTAD/CH3NH3PbI3 + m-Al2O3/ZnO/ITO/AgNW/ITO, exhibited a power conversion efficiency of 8.44% (comparable to that of the FTO/glass-based counterpart at 10.81%) and were stable for 30 days in ambient air. Our results demonstrate the feasibility of using AgNWs as a transparent bottom electrode in perovskite solar cells produced by a fully printable process.We report all-solution-processed transparent conductive electrodes based on Ag nanowire (AgNW)-embedded metal oxide composite films for application in organometal halide perovskite solar cells. To address the thermal instability of Ag nanowires, we used combustive sol-gel derived thin films to construct ZnO/ITO/AgNW/ITO composite structures. The resulting composite configuration effectively prevented the AgNWs from undergoing undesirable side-reactions with halogen ions present in the perovskite precursor solutions that significantly deteriorate the optoelectrical properties of Ag nanowires in transparent conductive films. AgNW-based composite electrodes had a transmittance of ~80% at 550 nm and sheet resistance of 18 Ω sq-1. Perovskite solar cells fabricated using a fully solution

  17. Polyimide composites: Application histories

    NASA Technical Reports Server (NTRS)

    Poveromo, L. M.

    1985-01-01

    Advanced composite hardware exposed to thermal environments above 127 C (260 F) must be fabricated from materials having resin matrices whose thermal/moisture resistance is superior to that of conventional epoxy-matrix systems. A family of polyimide resins has evolved in the last 10 years that exhibits the thermal-oxidative stability required for high-temperature technology applications. The weight and structural benefits for organic-matrix composites can now be extended by designers and materials engineers to include structures exposed to 316 F (600 F). Polyimide composite materials are now commercially available that can replace metallic or epoxy composite structures in a wide range of aerospace applications.

  18. Zinc oxide interdigitated electrode for biosensor application

    NASA Astrophysics Data System (ADS)

    Sin L., L.; Arshad, M. K. Md.; Fathil, M. F. M.; Adzhri, R.; M. Nuzaihan M., N.; Ruslinda, A. R.; Gopinath, Subash C. B.; Hashim, U.

    2016-07-01

    In biosensors, zinc oxide (ZnO) thin film plays a crucial role in term of stability, sensitivity, biocompatibility and low cost. Interdigitated electrode (IDE) design is one of the device architecture in biosensor for label free, stability and sensitivity. In this paper, we discuss the fabrication of zinc oxide deposited on the IDE as a transducer for sensing of biomolecule. The formation of APTES had increase the performance of the surface functionalization..Furthermore we extend the discuss on the surface functionalization process which is utilized for probe attachment onto the surface of biosensor through surface immobilization process, thus enables the sensing of biomolecules for biosensor application.

  19. Composite fiber structures for catalysts and electrodes

    NASA Technical Reports Server (NTRS)

    Marrion, Christopher J.; Cahela, Donald R.; Ahn, Soonho; Tatarchuk, Bruce J.

    1993-01-01

    We have recently envisioned a process wherein fibers of various metals in the 0.5 to 15 micron diameter range are slurried in concert with cellulose fibers and various other materials in the form of particulates and/or fibers. The resulting slurry is cast via a wet-lay process into a sheet and dried to produce a free-standing sheet of 'composite paper.' When the 'preform' sheet is sintered in hydrogen, the bulk of the cellulose is removed with the secondary fibers and/or particulates being entrapped by the sinter-locked network provided by the metal fibers. The resulting material is unique, in that it allows the intimate contacting and combination of heretofore mutually exclusive materials and properties. Moreover, due to the ease of paper manufacture and processing, the resulting materials are relatively inexpensive and can be fabricated into a wide range of three-dimensional structures. Also, because cellulose is both a binder and a pore-former, structures combining high levels of active surface area and high void volume (i.e., low pressure drop) can be prepared as freestanding flow through monoliths.

  20. Hexacyanoferrate-based composite ion-sensitive electrodes for voltammetry.

    PubMed

    Düssel, H; Dostal, A; Scholz, F

    1996-04-01

    Composite electrodes made of graphite, paraffin and metal hexacyanoferrates exhibit a voltammetric response of the hexacyanoferrate ions, the potential of which depends linearly on the logarithm of concentration of alkali and alkaline-earth metal ions. This behaviour has been observed on account of the fact that the electrochemical reaction is accompanied by an exchange of these ions between the solution and the zeolitic lattice of the hexacyanoferrates for charge compensation. The voltammetric determination of the formal potential of these electrodes in a solution allows the quantitative analysis of the ions which are exchanged between the metal hexacyanoferrates and the aqueous solutions. Iron(III), copper(II), silver(I), nickel(II) and cadmium(II) hexacyanoferrates have been studied for the determination of H(+), Li(+), Na(+), K(+), Rb(+), Cs(+), NH(+)(4), Mg(2+), Ca(2+) and Ba(2+). In some cases, the selectivity constants are as low as 3.10(-4), or even so small that their exact value is inaccessible. Electrodes made of iron (III), copper (II), silver (I), nickel (II) and cadmium (II) hexacyanoferrates are most suitable for the determination of potassium ions. Electrodes with nickel (II) and cadmium (II) hexacyanoferrates are also suitable for the determination of caesium ions. The working range of the electrodes also depends on the conductivity of the solutions and can range from 10(-5) to 1 mol l(-1). Typical standard deviations of the potential measurements are 3 mV. PMID:15045452

  1. Indium- and Platinum-Free Counter Electrode for Green Mesoscopic Photovoltaics through Graphene Electrode and Graphene Composite Catalysts: Interfacial Compatibility.

    PubMed

    Yin, Jie; Zhou, Huawei; Liu, Zhicheng; Nie, Zhonghao; Li, Yinhao; Qi, Xuan; Chen, Baoli; Zhang, Yingtian; Zhang, Xianxi

    2016-03-01

    The scarcity and noble indium and platinum (Pt) are important elements in photoelectric nanomaterials. Therefore, development of low cost alternative materials to meet different practical applications is an urgent need. Two-dimensional (2D) layered graphene (GE) with unique physical, mechanical, and electrical properties has recently drawn a great deal of attention in various optoelectronic fields. Herein, the large scale (21 cm × 15 cm) high-quality single layer graphene (SLG) and multilayer graphene on a flexible plastic substrate PET were controllably prepared through layer-by-layer (LBL) transfer using the thermal release adhesive transfer method (TRA-TM). Transmission and antibending performance based on PET/GE were superior to traditional PET/ITO. The square resistance of a nine-layer graphene electrode reached approximately 58 Ω. Combined with our newly developed and highly effective Fe3O4@RGO (reduced graphene oxide) catalyst, the power conversion efficiency of the dye-sensitized solar cell (DSC) using flexible PET/GE conductive substrate was comparable to that of the DSC using the PET/ITO substrate. The desirable performance of PET/GE/Fe3O4@RGO counter electrodes (low-cost indium- and platinum-free counter electrodes) is attributed to the interfacial compatibility between 2D graphene composite catalyst (Fe3O4@RGO) and 2D PET/GE conductive substrate. In addition, DSCs that use only PET/GE (without Fe3O4@RGO catalyst) as counter electrodes can also achieve a photocurrent density of 6.30 mA cm(-2). This work is beneficial for fundamental research and practical applications of graphene and graphene composite in photovoltaics, photocatalytic water splitting, supercapacitors. PMID:26838272

  2. Synthesis of 2D/2D Structured Mesoporous Co3O4 Nanosheet/N-Doped Reduced Graphene Oxide Composites as a Highly Stable Negative Electrode for Lithium Battery Applications.

    PubMed

    Sennu, Palanichamy; Kim, Hyo Sang; An, Jae Youn; Aravindan, Vanchiappan; Lee, Yun-Sung

    2015-08-01

    Mesoporous Co3O4 nanosheets (Co3 O4 -NS) and nitrogen-doped reduced graphene oxide (N-rGO) are synthesized by a facile hydrothermal approach, and the N-rGO/Co3O4 -NS composite is formulated through an infiltration procedure. Eventually, the obtained composites are subjected to various characterization techniques, such as XRD, Raman spectroscopy, surface area analysis, X-ray photoelectron spectroscopy (XPS), and TEM. The lithium-storage properties of N-rGO/Co3O4 -NS composites are evaluated in a half-cell assembly to ascertain their suitability as a negative electrode for lithium-ion battery applications. The 2D/2D nanostructured mesoporous N-rGO/Co3O4 -NS composite delivered a reversible capacity of about 1305 and 1501 mAh g(-1) at a current density of 80 mA g(-1) for the 1st and 50th cycles, respectively. Furthermore, excellent cyclability, rate capability, and capacity retention characteristics are noted for the N-rGO/Co3O4 -NS composite. This improved performance is mainly related to the existence of mesoporosity and a sheet-like 2D hierarchical morphology, which translates into extra space for lithium storage and a reduced electron pathway. Also, the presence of N-rGO and carbon shells in Co3O4 -NS should not be excluded from such exceptional performance, which serves as a reliable conductive channel for electrons and act as synergistically to accommodate volume expansion upon redox reactions. Ex-situ TEM, impedance spectroscopy, and XPS, are also conducted to corroborate the significance of the 2D morphology towards sustained lithium storage. PMID:26033848

  3. Magnetohydrodynamic electrode

    DOEpatents

    Boquist, Carl W.; Marchant, David D.

    1978-01-01

    A ceramic-metal composite suitable for use in a high-temperature environment consists of a refractory ceramic matrix containing 10 to 50 volume percent of a continuous high-temperature metal reinforcement. In a specific application of the composite, as an electrode in a magnetohydrodynamic generator, the one surface of the electrode which contacts the MHD fluid may have a layer of varying thickness of nonreinforced refractory ceramic for electrode temperature control. The side walls of the electrode may be coated with a refractory ceramic insulator. Also described is an electrode-insulator system for a MHD channel.

  4. Composite electrode for storage batteries and the like

    SciTech Connect

    Faber, P.

    1980-09-16

    A metal/synthetic-resin composite electrode for a storage battery or the like is comprised of a perforate metal support which is flanked on both sides by openworks of polyolefin, e.g., partially fluorinated polyolefin, which are welded together within the openings of the support and carry the active material. The polyolefin openworks, together with the active material, are covered in turn with polyester fabric or polyester felt permeable fine porous cover layers.

  5. Graphene versus oxides for transparent electrode applications

    NASA Astrophysics Data System (ADS)

    Sandana, V. E.; Rogers, D. J.; Teherani, F. Hosseini; Bove, P.; Razeghi, M.

    2013-03-01

    Due to their combination of good electrical conductivity and optical transparency, Transparent Conducting Oxides (TCOs) are the most common choice as transparent electrodes for optoelectronics applications. In particular, devices, such as LEDs, LCDs, touch screens and solar cells typically employ indium tin oxide. However, indium has some significant drawbacks, including toxicity issues (which are hampering manufacturing), an increasing rarefication (due to a combination of relative scarcity and increasing demand [1]) and resulting price increases. Moreover, there is no satisfactory option at the moment for use as a p-type transparent contact. Thus alternative materials solutions are actively being sought. This review will compare the performance and perspectives of graphene with respect to TCOs for use in transparent conductor applications.

  6. Compliant Electrode and Composite Material for Piezoelectric Wind and Mechanical Energy Conversions

    NASA Technical Reports Server (NTRS)

    Chen, Bin (Inventor)

    2015-01-01

    A thin film device for harvesting energy from wind. The thin film device includes one or more layers of a compliant piezoelectric material formed from a composite of a polymer and an inorganic material, such as a ceramic. Electrodes are disposed on a first side and a second side of the piezoelectric material. The electrodes are formed from a compliant material, such as carbon nanotubes or graphene. The thin film device exhibits improved resistance to structural fatigue upon application of large strains and repeated cyclic loadings.

  7. Electrodeposition of Gold on Lignocelluloses and Graphite-Based Composite Paper Electrodes for Superior Electrical Properties

    NASA Astrophysics Data System (ADS)

    Sultana, Ishrat; Razaq, Aamir; Idrees, M.; Asif, M. H.; Ali, Hassan; Arshad, Asim; Iqbal, Shahid; Ramay, Shahid M.; Hussain, Shahzada Qamar

    2016-06-01

    Graphite-based composites are commonly used as an anode and current collector for energy storage devices; however, they have inherently limited potential for large scale rechargeable systems due to a brittle structure. In this study, flexible and light-weight graphite-based electrodes are prepared by incorporation of lignocelluloses fibers directly collected from a self-growing plant, Typha Angistifolia. Electrical properties of graphite and lignocelluloses composite sheets are enhanced by electrodeposition of gold in a three-electrode setup. Electrochemical deposition of gold on a lignocelluloses/graphite paper electrode was obtained in potentiostatic mode by the application of reduction potential -0.95 V for 2000 s, 600 s, and 100 s. The gold-deposited paper electrodes showed efficient kinetics by shifting redox peaks towards lower potentials in cyclic voltammetry measurements, whereas impedance measurements revealed seven orders of magnitude reduction in the resistive properties. Incorporated flexibility and superior electrical/electrochemical performance within presented graphite-based composites will provide cutting-edge characteristics for high-tech application of energy storage devices by keeping a focus on modern disposable technology.

  8. Fully solution-processed transparent electrodes based on silver nanowire composites for perovskite solar cells.

    PubMed

    Kim, Areum; Lee, Hongseuk; Kwon, Hyeok-Chan; Jung, Hyun Suk; Park, Nam-Gyu; Jeong, Sunho; Moon, Jooho

    2016-03-28

    We report all-solution-processed transparent conductive electrodes based on Ag nanowire (AgNW)-embedded metal oxide composite films for application in organometal halide perovskite solar cells. To address the thermal instability of Ag nanowires, we used combustive sol-gel derived thin films to construct ZnO/ITO/AgNW/ITO composite structures. The resulting composite configuration effectively prevented the AgNWs from undergoing undesirable side-reactions with halogen ions present in the perovskite precursor solutions that significantly deteriorate the optoelectrical properties of Ag nanowires in transparent conductive films. AgNW-based composite electrodes had a transmittance of ∼80% at 550 nm and sheet resistance of 18 Ω sq(-1). Perovskite solar cells fabricated using a fully solution-processed transparent conductive electrode, Au/spiro-OMeTAD/CH3NH3PbI3 + m-Al2O3/ZnO/ITO/AgNW/ITO, exhibited a power conversion efficiency of 8.44% (comparable to that of the FTO/glass-based counterpart at 10.81%) and were stable for 30 days in ambient air. Our results demonstrate the feasibility of using AgNWs as a transparent bottom electrode in perovskite solar cells produced by a fully printable process. PMID:26465213

  9. Highly efficient flexible optoelectronic devices using metal nanowire-conducting polymer composite transparent electrode

    NASA Astrophysics Data System (ADS)

    Jung, Eui Dae; Nam, Yun Seok; Seo, Houn; Lee, Bo Ram; Yu, Jae Choul; Lee, Sang Yun; Kim, Ju-Young; Park, Jang-Ung; Song, Myoung Hoon

    2015-09-01

    Here, we report a comprehensive analysis of the electrical, optical, mechanical, and surface morphological properties of composite nanostrutures based on silver nanowires (AgNW) and PEDOT:PSS conducting polymer for the use as flexible and transparent electrodes. Compared to ITO or the single material of AgNW or PEDOT:PSS, the AgNW/PEDOT:PSS composite electrode showed high electrical conductivity with a low sheet resistance of 26.8 Ω/sq at 91% transmittance (at 550 nm), improves surface smoothness, and enhances mechanical properties assisted by an amphiphilic fluoro-surfactant. The polymeric light-emitting diodes (PLEDs) and organic solar cells (OSCs) using the AgNW/PEDOT:PSS composite electrode showed higher device performances than those with AgNW and PEDOT:PSS electrodes and excellent flexibility under bending test. These results indicates that the AgNW/PEDOT:PSS composite presented is a good candidate as next-generation transparent elelctrodes for applications into flexible optoelectronic devices. [Figure not available: see fulltext.

  10. High surface area, low weight composite nickel fiber electrodes

    NASA Technical Reports Server (NTRS)

    Johnson, Bradley A.; Ferro, Richard E.; Swain, Greg M.; Tatarchuk, Bruce J.

    1993-01-01

    The energy density and power density of light weight aerospace batteries utilizing the nickel oxide electrode are often limited by the microstructures of both the collector and the resulting active deposit in/on the collector. Heretofore, these two microstructures were intimately linked to one another by the materials used to prepare the collector grid as well as the methods and conditions used to deposit the active material. Significant weight and performance advantages were demonstrated by Britton and Reid at NASA-LeRC using FIBREX nickel mats of ca. 28-32 microns diameter. Work in our laboratory investigated the potential performance advantages offered by nickel fiber composite electrodes containing a mixture of fibers as small as 2 microns diameter (Available from Memtec America Corporation). These electrode collectors possess in excess of an order of magnitude more surface area per gram of collector than FIBREX nickel. The increase in surface area of the collector roughly translates into an order of magnitude thinner layer of active material. Performance data and advantages of these thin layer structures are presented. Attributes and limitations of their electrode microstructure to independently control void volume, pore structure of the Ni(OH)2 deposition, and resulting electrical properties are discussed.

  11. Towards industrial applications of graphene electrodes

    NASA Astrophysics Data System (ADS)

    Bae, Sukang; Kim, Sang Jin; Shin, Dolly; Ahn, Jong-Hyun; Hong, Byung Hee

    2012-01-01

    Since the first isolation of graphene in 2004 by mechanical exfoliation from graphite, many people have tried to synthesize large-scale graphene using various chemical methods. In particular, there has been a great number of advances in the synthesis of graphene using chemical vapor deposition (CVD) on metal substrates such as Ni and Cu. Recently, a method to synthesize ultra-large-scale (~30 inch) graphene films using roll-to-roll transfer and chemical doping processes was developed that shows excellent electrical and physical properties suitable for practical applications on a large scale. Considering the outstanding scalability/processibility of roll-to-roll and CVD methods as well as the extraordinary flexibility/conductivity of graphene films, we expect that transparent graphene electrodes can replace indium tin oxide in the near future.

  12. Carbon Film Electrodes For Super Capacitor Applications

    DOEpatents

    Tan, Ming X.

    1999-07-20

    A method for treating an organic polymer material, preferably a vinylidene chloride/vinyl chloride copolymer (Saran) to produce a flat sheet of carbon film material having a high surface area (.apprxeq.1000 m.sup.2 /g) suitable as an electrode material for super capacitor applications. The method comprises heating a vinylidene chloride/vinyl chloride copolymer film disposed between two spaced apart graphite or ceramic plates to a first temperature of about 160.degree. C. for about 14 hours to form a stabilized vinylidene chloride/vinyl chloride polymer film, thereafter heating the stabilized film to a second temperature of about 750.degree. C. in an inert atmosphere for about one hour to form a carbon film; and finally activating the carbon film to increase the surface area by heating the carbon film in an oxidizing atmosphere to a temperature of at least 750-850.degree. C. for between 1-6 hours.

  13. Polypyrrole composite electrodes in an all-polymer battery system

    SciTech Connect

    Killian, J.G.; Coffey, B.M.; Gao, F.; Poehler, T.O.; Searson, P.C.

    1996-03-01

    The authors have fabricated an all-polymer battery utilizing the redox properties of electrically conducting polymers for the anode and cathode in conjunction with an ionic conducting polymer gel electrolyte. The anode and cathode consist of pyrrole electropolymerized onto a graphite fiber substrate resulting in a high-surface-area, composite electrode. A polymer gel electrolyte, based on polyacrylonitrile, was solution cast onto the electrodes to form an all-polymer cell. This system exhibits a specific charge capacity of 22 mAh/g based on the electroactive mass of the cathode and discharging the system to 0.4 V. These cells show no loss of capacity when cycled to 100 cycles.

  14. Carbon/ λ-MnO 2 composites for supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Malak-Polaczyk, A.; Matei-Ghimbeu, C.; Vix-Guterl, C.; Frackowiak, E.

    2010-04-01

    In the present work a composite of carbon with λ-MnO 2 have been synthesized by a simple two-step route. In the first step, to obtain LiMn 2O 4/carbon material, mesoporous activated carbon was impregnated with the solution of precursor metal salts and heated subsequently. As-prepared materials were acid treated which resulted in the formation of λ-MnO 2/carbon. Physical properties, structure and specific surface area of electrode materials were studied by TEM, X-ray diffraction and nitrogen sorption measurements. Voltammetry cycling, galvanostatic charge/discharge and impedance spectroscopy measurements performed in two- and three-electrode cells have been applied in order to measure electrochemical parameters. TEM images confirmed well dispersed λ-MnO 2 particles on the surface of carbon material. The carbon in the composite plays an important role as the surface area enhancing component and a support of pseudocapacitive material. Furthermore, the through-connected porosity serves as a continuous pathway for electrolyte transport. A synergetic effect of the porous carbon framework and of the redox properties of the λ-MnO 2 is at the origin of improvement of specific capacitance values which has been observed for composites after delithiation.

  15. High Performance Nickel Electrodes for Space Power Applications

    NASA Technical Reports Server (NTRS)

    Adanuvor, Prosper K.; Pearson, Johnnie A.; Miller, Brian; Tatarchuk, Bruce; Britton, Doris L.

    1996-01-01

    Performance characteristics such as efficiency, specific energy density and power density of nickel electrodes are generally limited by the electrode microstructure and nature of the active material within the electrode matrix. Progress is being made in our laboratory in a collaborative effort with NASA-Lewis Research Center to develop lighter weight, mechanically stable and highly efficient nickel electrodes for aerospace applications. Our approach is based on an electrode microstructure fabricated from a mixture of nickel fibers as small as 2 microns diameter and cellulose fibers. Performance data in flooded cell tests and cycle life data are presented. Performance characteristics are compared to other electrode microstructures such as the Fibrex Fiber mat and the Fibrex Powder substrate. The flexibility of our electrode microstructure and the significant advantages it offers in terms of weight and performance are demonstrated, in particular, its ability to accept charge at high rates and to discharge at high rates.

  16. High performance nickel electrodes for space power applications

    NASA Technical Reports Server (NTRS)

    Adanuvor, Prosper K.; Pearson, Johnnie A.; Miller, Brian; Tatarchuk, Bruce; Britton, Doris L.

    1995-01-01

    The specific energy density and the performance of nickel electrodes are generally limited by the electrode microstructure and the nature of the active material within the electrode matrix. Progress is being made in our laboratory in a collaborative effort with NASA-LEWIS Research Center to develop lighter weight, mechanically stable and highly efficient nickel electrodes for aerospace applications. Our approach is based on an electrode microstructure fabricated from a mixture of nickel fibers as small as 2 micro m diameter and cellulose fibers. Results will be presented to show the optimum conditions for impregnating this electrode microstructure with nickel hydroxide active material. Performance data in half-cell tests and cycle life data will also be presented. The flexibility of this electrode microstructure and the significant advantages it offers in terms of weight and performance will be demonstrated, in particular its ability to accept charge at high rates and to discharge at high rates.

  17. Composite Metal-hydrogen Electrodes for Metal-Hydrogen Batteries

    SciTech Connect

    Ruckman, M W; Wiesmann, H; Strongin, M; Young, K; Fetcenko, M

    1997-04-01

    The purpose of this project is to develop and conduct a feasibility study of metallic thin films (multilayered and alloy composition) produced by advanced sputtering techniques for use as anodes in Ni-metal hydrogen batteries. The anodes could be incorporated in thin film solid state Ni-metal hydrogen batteries that would be deposited as distinct anode, electrolyte and cathode layers in thin film devices. The materials could also be incorporated in secondary consumer batteries (i.e. type AF(4/3 or 4/5)) which use electrodes in the form of tapes. The project was based on pioneering studies of hydrogen uptake by ultra-thin Pd-capped metal-hydrogen ratios exceeding and fast hydrogen charging and Nb films, these studies suggested that materials with those of commercially available metal hydride materials discharging kinetics could be produced. The project initially concentrated on gas phase and electrochemical studies of Pd-capped niobium films in laboratory-scale NiMH cells. This extended the pioneering work to the wet electrochemical environment of NiMH batteries and exploited advanced synchrotron radiation techniques not available during the earlier work to conduct in-situ studies of such materials during hydrogen charging and discharging. Although batteries with fast charging kinetics and hydrogen-metal ratios approaching unity could be fabricated, it was found that oxidation, cracking and corrosion in aqueous solutions made pure Nb films-and multiiayers poor candidates for battery application. The project emphasis shifted to alloy films based on known elemental materials used for NiMH batteries. Although commercial NiMH anode materials contain many metals, it was found that 0.24 µm thick sputtered Zr-Ni films cycled at least 50 times with charging efficiencies exceeding 95% and [H]/[M] ratios of 0.7-1.0. Multilayered or thicker Zr-Ni films could be candidates for a thin film NiMH battery that may have practical applications as an integrated power source for

  18. Electrodeposited reduced-graphene oxide/cobalt oxide electrodes for charge storage applications

    NASA Astrophysics Data System (ADS)

    García-Gómez, A.; Eugénio, S.; Duarte, R. G.; Silva, T. M.; Carmezim, M. J.; Montemor, M. F.

    2016-09-01

    In the present work, electrochemically reduced-graphene oxide/cobalt oxide composites for charge storage electrodes were prepared by a one-step pulsed electrodeposition route on stainless steel current collectors and after that submitted to a thermal treatment at 200 °C. A detailed physico-chemical characterization was performed by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and Raman spectroscopy. The electrochemical response of the composite electrodes was studied by cyclic voltammetry and charge-discharge curves and related to the morphological and phase composition changes induced by the thermal treatment. The results revealed that the composites were promising materials for charge storage electrodes for application in redox supercapacitors, attaining specific capacitances around 430 F g-1 at 1 A g-1 and presenting long-term cycling stability.

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

    PubMed

    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. PMID:21887427

  20. Expansion and shrinkage of the sulfur composite electrode in rechargeable lithium batteries

    NASA Astrophysics Data System (ADS)

    He, Xiangming; Ren, Jianguo; Wang, Li; Pu, Weihua; Jiang, Changyin; Wan, Chunrong

    The expansion and shrinkage characteristics of sulfur composite cathode electrode in rechargeable lithium batteries have been investigated. It was found that the sulfur composites electrodes expanded when discharging and shrank when charging again. The thickness change of the electrode was measured to be about 22%. The thickness of lithium metal anodes was also changed when lithium deposition and dissolution, while the sulfur composites electrodes expanded and shrank conversely. The investigation showed that the thickness changes of lithium anode and sulfur composite cathode could be compensated with each other to keep the total thickness of the cell not to change so much.

  1. Polyaniline nanofiber/large mesoporous carbon composites as electrode materials for supercapacitors

    NASA Astrophysics Data System (ADS)

    Liu, Huan; Xu, Bin; Jia, Mengqiu; Zhang, Mei; Cao, Bin; Zhao, Xiaonan; Wang, Yu

    2015-03-01

    A composite of polyaniline nanofiber/large mesoporous carbon (PANI-F/LMC) hybrid was prepared by an in situ chemical oxidative polymerization of aniline monomer with nano-CaCO3 templated LMC as host matrix for supercapacitors. The morphology, composition and electronic structure of the composites (PANI-F/LMC) together with pure PANI nanofibers and the LMC were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), FT-IR, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It is found that the PANI nanofibers were incorporated into the large mesochannels of LMC with interpenetrating framework formed. Such unique structure endows the PANI-F/LMC composite with a high capacitance of 473 F g-1 at a current load of 0.1 A g-1 with good rate performance and cycling stability, suggesting its potential application in the electrode material for supercapacitors.

  2. High-power supercapacitor electrodes from single-walled carbon nanohorn/nanotube composite.

    PubMed

    Izadi-Najafabadi, Ali; Yamada, Takeo; Futaba, Don N; Yudasaka, Masako; Takagi, Hideyuki; Hatori, Hiroaki; Iijima, Sumio; Hata, Kenji

    2011-02-22

    A novel composite is presented as a supercapacitor electrode with a high maximum power rating (990 kW/kg; 396 kW/l) exceeding power performances of other electrodes. The high-power capability of the electrode stemmed from its unique meso-macro pore structure engineered through the utilization of single-walled carbon nanotubes (20 wt %) as scaffolding for single-walled carbon nanohorns (80 wt %). The novel composite electrode also exhibited durable operation (6.5% decline in capacitance over 100 000 cycles) as a result of its monolithic chemical composition and mechanical stability. The novel composite electrode was benchmarked against another high-power electrode made from single-walled carbon nanotubes (Bucky paper electrode). While the composite electrode had a lower surface area compared to the Bucky paper electrode (280 vs 470 m(2)/g from nitrogen adsorption), it had a higher meso-macro pore volume (2.6 vs 1.6 mL/g from mercury porosimetry) which enabled the composite electrode to retain more electrolyte, ensuring facile ion transport, hence achieving a higher maximum power rating (970 vs 400 kW/kg). PMID:21210712

  3. Microfabricated Reference Electrodes and their Biosensing Applications

    PubMed Central

    Shinwari, M. Waleed; Zhitomirsky, David; Deen, Imran A.; Selvaganapathy, P. R.; Deen, M. Jamal; Landheer, D.

    2010-01-01

    Over the past two decades, there has been an increasing trend towards miniaturization of both biological and chemical sensors and their integration with miniaturized sample pre-processing and analysis systems. These miniaturized lab-on-chip devices have several functional advantages including low cost, their ability to analyze smaller samples, faster analysis time, suitability for automation, and increased reliability and repeatability. Electrical based sensing methods that transduce biological or chemical signals into the electrical domain are a dominant part of the lab-on-chip devices. A vital part of any electrochemical sensing system is the reference electrode, which is a probe that is capable of measuring the potential on the solution side of an electrochemical interface. Research on miniaturization of this crucial component and analysis of the parameters that affect its performance, stability and lifetime, is sparse. In this paper, we present the basic electrochemistry and thermodynamics of these reference electrodes and illustrate the uses of reference electrodes in electrochemical and biological measurements. Different electrochemical systems that are used as reference electrodes will be presented, and an overview of some contemporary advances in electrode miniaturization and their performance will be provided. PMID:22294894

  4. Characterization of interdigitated electrode piezoelectric fiber composites under high electrical and mechanical loading

    NASA Astrophysics Data System (ADS)

    Rodgers, John P.; Bent, Aaron A.; Hagood, Nesbitt W.

    1996-05-01

    The primary objective of this work is to develop a standard methodology for characterizing structural actuation systems intended for operation in high electrical and mechanical loading environments. The designed set of tests evaluates the performance of the active materials system under realistic operating conditions. The tests are also used to characterize piezoelectric fiber composites which have been developed as an alternative to monolithic piezoceramic wafers for structural actuation applications. The performance of this actuator system has been improved using an interdigitated electrode pattern, which orients the primary component of the electric field into the plane of the structure, enabling the use of the primary piezoelectric effect along the active fibers. One possible application of this technology is in the integral twist actuation of helicopter rotor blades for higher harmonic control. This application requires actuators which can withstand the harsh rotor blade operating environment. This includes large numbers of electrical and mechanical cycles with considerable centripetal and bending loads. The characterization tests include standard active material tests as well as application-driven tests which evaluate the performance of the actuators during simulated operation. Test results for several actuator configurations are provided, including S2 glass- reinforced and E-glass laminated actuators. The study concludes that the interdigitated electrode piezoelectric fiber composite actuator has great potential for high loading applications.

  5. Second Generation of Lead-lead Chloride Electrodes for Geophysical Applications

    NASA Astrophysics Data System (ADS)

    Petiau, G.

    A large number of geophysical applications need long-term telluric recordings. In order to realise it correctly, the use of very stable electrodes is necessary. The study of the potential variations of Pb-PbCl2 electrodes as a function of both the ionic composition and the pH of its electrolyte allows one to chose the optimal working criteria. The best stability and the minimum noise for the potential are obtained for a solution saturated in both salts PbCl2 and KCl, or PbCl2 and NaCl, in the presence of additional non-dissolved salts, with a pH from 4 to 5. The study of the salts diffusion between the inside of the electrode and the outside medium allows one to compute the time span over which the potential remains stable (tD time of dissaturation), and to know how to increase it. Two solutions are possible. The first one is to increase the electrode length, because tD is proportional to the length squared. The second one is to reduce the exchanges of salts with the external medium, by using an electrode with a narrow channel. In this case, tD is proportional to the quantity of non-dissolved salt in the electrode and to the internal electrical resistance of the electrode. The fabrication of this new electrodes design with a channel is described.

  6. Composite prepreg application device

    NASA Technical Reports Server (NTRS)

    Sandusky, Donald A. (Inventor); Marchello, Joseph M. (Inventor)

    1996-01-01

    A heated shoe and cooled pressure roller assembly for composite prepreg application is provided. The shoe assembly includes a heated forward contact surface having a curved pressure surface. The following cooled roller provides a continuous pressure to the thermoplastic while reducing the temperature to approximately 5.degree. C. below glass transition temperature. Electric heating coils inside the forward portion of the shoe heat a thermoplastic workpiece to approximately 100.degree. C. above the glass transition. Immediately following the heated contact surface, a cooled roller cools the work. The end sharpened shape of the heated shoe trailing edge tends to prevent slag buildup and maintain a uniform, relaxed stress fabrication.

  7. Microfibrous nickel substrates and electrodes for battery system applications

    NASA Astrophysics Data System (ADS)

    Zhu, Wenhua H.; Durben, Peter J.; Tatarchuk, Bruce J.

    The use of microfibrous nickel substrates is advantageous for increasing the surface area available for the deposition of active material and reducing the substrate weight and consequently, yields a higher specific capacity for nickel hydroxide electrodes. Porous, microfiber-based nickel substrates were produced by sintering a composite preform. The preforms, consisting of nickel fibers with diameters as small as 2 μm and cellulose fibers, were formed using a papermaking process. The fabricated nickel electrodes that included a supporting nickel mesh in the substrate tested in a 26% KOH half-cell delivered a specific capacity of more than 250 mAh/g of the electrode weight (i.e. fibrous substrate, nickel mesh, and active material) at a 1.0 C discharge rate. An Auburn electrode without a nickel mesh tested in the same half-cell attained a higher specific capacity of 268 mAh/g at a 1.37 C discharge rate. The substrates used in these electrodes had porosities of 95-97%, and greatly improved the specific capacity of the nickel electrode. With the use of the microfibrous electrode, improved specific energies of nickel-based cell and battery designs are possible. When assembled in a nickel-hydrogen (Ni-H 2) boilerplate cell, the specific capacity of nearly 230 mAh/g was observed for the nickel electrode at a 0.5 C rate during the 127th cycle test. The results of high specific capacity and quick rise in utilization of microfibrous nickel hydroxide electrodes make these electrodes good candidates for significantly improving the energy density and performance of nickel-hydrogen cells.

  8. Graphene Oxide/ Ruthenium Oxide Composites for Supercapacitors Electrodes

    NASA Astrophysics Data System (ADS)

    Amir, Fatima

    Supercapacitors are electrical energy storage devices with high power density, high rate capability, low maintenance cost, and long life cycle. They complement or replace batteries in harvesting applications when high power delivery is needed. An important improvement in performance of supercapacitors has been achieved through recent advances in the development of new nanostructured materials. Here we will discuss the fabrication of graphene oxide/ ruthenium oxide supercacitors electrodes including electrophoretic deposition. The morphology and structure of the fabricated electrodes were investigated and will be discussed. The electrochemical properties were determined using cyclic voltammetry and galvanostatic charge/discharge techniques and the experiments that demonstrate the excellent capacitive properties of the obtained supercapacitors will also be discussed. The fabrication and characterization of the samples were performed at the Center of Functional Nanomaterials at Brookhaven National Lab. The developed approaches in our study represent an exciting direction for designing the next generation of energy storage devices. This work was supported in part by the U.S. Department of Energy through the Visiting Faculty Program and the research used resources of the Center for Functional Nanomaterials at Brookhaven National Laboratory.

  9. Robust myoelectric signal detection based on stochastic resonance using multiple-surface-electrode array made of carbon nanotube composite paper

    NASA Astrophysics Data System (ADS)

    Shirata, Kento; Inden, Yuki; Kasai, Seiya; Oya, Takahide; Hagiwara, Yosuke; Kaeriyama, Shunichi; Nakamura, Hideyuki

    2016-04-01

    We investigated the robust detection of surface electromyogram (EMG) signals based on the stochastic resonance (SR) phenomenon, in which the response to weak signals is optimized by adding noise, combined with multiple surface electrodes. Flexible carbon nanotube composite paper (CNT-cp) was applied to the surface electrode, which showed good performance that is comparable to that of conventional Ag/AgCl electrodes. The SR-based EMG signal system integrating an 8-Schmitt-trigger network and the multiple-CNT-cp-electrode array successfully detected weak EMG signals even when the subject’s body is in the motion, which was difficult to achieve using the conventional technique. The feasibility of the SR-based EMG detection technique was confirmed by demonstrating its applicability to robot hand control.

  10. Carbon film electrodes for super capacitor applications

    DOEpatents

    Tan, Ming X.

    1999-01-01

    A microporous carbon film for use as electrodes in energy strorage devices is disclosed, which is made by the process comprising the steps of: (1) heating a polymer film material consisting essentially of a copolymer of polyvinylidene chloride and polyvinyl chloride in an inert atmosphere to form a carbon film; and (2) activating said carbon film to form said microporous carbon film having a density between about 0.7 g/cm.sup.2 and 1 g/cm.sup.2 and a gravimetric capacitance of about between 120 F/g and 315 F/g.

  11. Aqueous processing of composite lithium ion electrode material

    SciTech Connect

    Li, Jianlin; Armstrong, Beth L; Daniel, Claus; Wood, III, David L

    2015-02-17

    A method of making a battery electrode includes the steps of dispersing an active electrode material and a conductive additive in water with at least one dispersant to create a mixed dispersion; treating a surface of a current collector to raise the surface energy of the surface to at least the surface tension of the mixed dispersion; depositing the dispersed active electrode material and conductive additive on a current collector; and heating the coated surface to remove water from the coating.

  12. Coated-Wire Ion Selective Electrodes and Their Application to the Teaching Laboratory.

    ERIC Educational Resources Information Center

    Martin, Charles R.; Freiser, Henry

    1980-01-01

    Describes the procedures for construction of a nitrate coated-wire ion selective electrode and suggests experiments for evaluation of electrode response and illustration of typical analytical applications of ion selective electrodes. (CS)

  13. Layer by Layer Ex-Situ Deposited Cobalt-Manganese Oxide as Composite Electrode Material for Electrochemical Capacitor

    PubMed Central

    Rusi; Chan, P. Y.; Majid, S. R.

    2015-01-01

    The composite metal oxide electrode films were fabricated using ex situ electrodeposition method with further heating treatment at 300°C. The obtained composite metal oxide film had a spherical structure with mass loading from 0.13 to 0.21 mg cm-2. The structure and elements of the composite was investigated using X-ray diffraction (XRD) and energy dispersive X-ray (EDX). The electrochemical performance of different composite metal oxides was studied by cyclic voltammetry (CV) and galvanostatic charge-discharge (CD). As an active electrode material for a supercapacitor, the Co-Mn composite electrode exhibits a specific capacitance of 285 Fg-1 at current density of 1.85 Ag-1 in 0.5M Na2SO4 electrolyte. The best composite electrode, Co-Mn electrode was then further studied in various electrolytes (i.e., 0.5M KOH and 0.5M KOH/0.04M K3Fe(CN) 6 electrolytes). The pseudocapacitive nature of the material of Co-Mn lead to a high specific capacitance of 2.2 x 103 Fg-1 and an energy density of 309 Whkg-1 in a 0.5MKOH/0.04MK3Fe(CN) 6 electrolyte at a current density of 10 Ag-1. The specific capacitance retention obtained 67% of its initial value after 750 cycles. The results indicate that the ex situ deposited composite metal oxide nanoparticles have promising potential in future practical applications. PMID:26158447

  14. Electrophoretic nanotechnology of composite electrodes for electrochemical supercapacitors.

    PubMed

    Su, Y; Zhitomirsky, I

    2013-02-14

    The electrophoretic deposition (EPD) method has been developed for the fabrication of MnO(2)-multiwalled carbon nanotube (MWCNT) films for application in electrochemical supercapacitors (ESs). For MWCNT applications, which depend on electrical conductivity, it is challenging to achieve dispersion and EPD of pristine MWCNT and avoid defects due to chemical treatment or functionalization. An important finding was the possibility of efficient dispersion and controlled EPD of MWCNT using calconcarboxylic acid (CCA). Moreover, the use of CCA allowed efficient dispersion of MnO(2) in concentrated suspensions and EPD of MnO(2) films. The comparison of the experimental data for chromotrope FB (CFB) and CCA and chemical structures of the molecules provided insight into the mechanism of CCA adsorption on MnO(2). The fabrication of stable suspensions of MnO(2) nanoparticles containing MWCNT, and controlled codeposition of both materials is a crucial aspect in the EPD of composites. The new approach was based on the use of CCA as a charging and dispersing agent for EPD of MnO(2) nanoparticles and MWCNT. The deposition yield measurements at various experimental conditions and Fourier transform infrared spectroscopy data, coupled with results of electron microscopy, thermogravimetric, and differential thermal analysis provided evidence of the formation of MnO(2)-MWCNT composites. The electrochemical testing results and impedance spectroscopy data showed good capacitive behavior of the composite films and the beneficial effect of MWCNTs. PMID:22662969

  15. Capacitance behavior of nanostructured ɛ-MnO2/C composite electrode using different carbons matrix

    NASA Astrophysics Data System (ADS)

    Tran, Van Man; Ha, An The; Loan Phung Le, My

    2014-06-01

    In this work nanostructured ɛ-MnO2/C composite electrode was synthesized via the reduction reaction of potassium permanganate. A wide range of carbons such as mesoporous carbon (MC), graphite (GC), super P carbon (super P) and Vulcan carbon (VC) were used in order to enhance the interfacial electrical conductivity and the electrochemical capacitance of the composite electrodes. Physical properties, structure and specific surface area of electrode materials were investigated by scanning electron microscopy (SEM), x-ray diffraction and nitrogen adsorption measurements. The capacitance behavior of MnO2/C materials was studied in aqueous and non-aqueous solution using cyclic voltammetry, galvanostatic charge/discharge and impedance spectroscopy measurements. The composite electrode exhibits the highest capacitance at 30 wt% activated carbon. Among different carbons used, the maximum capacitance of MnO2/super P electrode is as high as 205 F g-1 at 50 mV s-1 and retains 98% after 300 cycles.

  16. Flexible Electrode Design: Fabrication of Freestanding Polyaniline-Based Composite Films for High-Performance Supercapacitors.

    PubMed

    Khosrozadeh, Ali; Darabi, Mohammad Ali; Xing, Malcolm; Wang, Quan

    2016-05-11

    Polyaniline (PANI) is a promising pseudocapacitance electrode material. However, its structural instability leads to low cyclic stability and limited rate capability which hinders its practical applications. In view of the limitations, flexible PANI-based composite films are developed to improve the electrochemical performance of electrode materials. We report in the research a facile and cost-effective approach for fabrication of a high-performance supercapacitor (SC) with excellent cyclic stability and tunable energy and power densities. SC electrode containing a very high mass loading of active materials is a flexible film of PANI, tissue wiper-based cellulose, graphite-based exfoliated graphite (ExG), and silver nanoparticles with potential applications in wearable electronics. The optimum preparation weight ratios of silver nitrate/aniline and ExG/aniline used in the research are estimated to be 0.18 and 0.65 (or higher), respectively. Our results show that an ultrahigh capacitance of 3.84 F/cm(2) (240.10 F/g) at a discharge rate of 5 mA can be achieved. In addition, our study shows that the power density can be increased from 1531.3 to 3000 W/kg by selecting the weight ratio of ExG/aniline to be more than 0.65, with a sacrifice in the energy density. The obtained promising electrochemical properties are found to be mainly attributed to an effective combination of PANI, ExG, cushiony cellulose scaffold, and silver as well as the porosity of the composite. PMID:27116563

  17. PEDOT-based composites as electrode materials for supercapacitors.

    PubMed

    Zhao, Zhiheng; Richardson, Georgia F; Meng, Qingshi; Zhu, Shenmin; Kuan, Hsu-Chiang; Ma, Jun

    2016-01-29

    Poly (3, 4-ethylenedioxythiophene) (denoted PEDOT) already has a brief history of being used as an active material in supercapacitors. It has many advantages such as low-cost, flexibility, and good electrical conductivity and pseudocapacitance. However, the major drawback is low stability, which means an obvious capacitance drop after a certain number of charge-discharge cycles. Another disadvantage is its limited capacitance and this becomes an issue for industrial applications. To solve these problems, there are several approaches including the addition of conducting nanofillers to increase conductivity, and mixing or depositing metal oxide to enhance capacitance. Furthermore, expanding the surface area of PEDOT is one of the main methods to improve its performance in energy storage applications through special processes; for example using a three-dimensional substrate or preparing PEDOT aerogel through freeze drying. This paper reviews recent techniques and outcomes of PEDOT based composites for supercapacitors, as well as detailed calculations about capacitances. Finally, this paper outlines the new direction and recent challenges of PEDOT based composites for supercapacitor applications. PMID:26656436

  18. PEDOT-based composites as electrode materials for supercapacitors

    NASA Astrophysics Data System (ADS)

    Zhao, Zhiheng; Richardson, Georgia F.; Meng, Qingshi; Zhu, Shenmin; Kuan, Hsu-Chiang; Ma, Jun

    2016-01-01

    Poly (3, 4-ethylenedioxythiophene) (denoted PEDOT) already has a brief history of being used as an active material in supercapacitors. It has many advantages such as low-cost, flexibility, and good electrical conductivity and pseudocapacitance. However, the major drawback is low stability, which means an obvious capacitance drop after a certain number of charge-discharge cycles. Another disadvantage is its limited capacitance and this becomes an issue for industrial applications. To solve these problems, there are several approaches including the addition of conducting nanofillers to increase conductivity, and mixing or depositing metal oxide to enhance capacitance. Furthermore, expanding the surface area of PEDOT is one of the main methods to improve its performance in energy storage applications through special processes; for example using a three-dimensional substrate or preparing PEDOT aerogel through freeze drying. This paper reviews recent techniques and outcomes of PEDOT based composites for supercapacitors, as well as detailed calculations about capacitances. Finally, this paper outlines the new direction and recent challenges of PEDOT based composites for supercapacitor applications.

  19. Review on advances in porous nanostructured nickel oxides and their composite electrodes for high-performance supercapacitors

    NASA Astrophysics Data System (ADS)

    Sk, Md Moniruzzaman; Yue, Chee Yoon; Ghosh, Kalyan; Jena, Rajeeb Kumar

    2016-03-01

    Recently, porous nanostructured transition metal oxides with excellent electrochemical performance have become a new class of energy storage materials for supercapacitors. The ever-growing global demand of electrically powered devices makes it imperative to develop renewable, efficient and reliable electrochemical energy storage devices. This review article focuses on the Ni based transition metal oxides and their composite electrode materials including carbons, metals and transition metal oxides for supercapacitor applications, providing an overview on the charge mechanisms, methodologies and nanostructures discovered in recent years, and latest research findings. The NiO and their composites possess higher reversible capacity, good structural stability, and have been studied for usage as novel electrode materials for supercapacitors. Their fine-tuned physical and chemical properties make them ideal candidates for supercapacitor applications as they possess higher accessible electroactive sites, which will provide both high power density and also high energy density. Moreover, synergistic effects can be derived from the constituent materials of the NiO based composite electrodes. The potential problems like device fabrication, measurement techniques, and future prospects of utilizing these materials as supercapacitor electrodes highlighting the fundamental understanding of the relationship between electrochemical and structural performances are also discussed.

  20. Composite polymer positive electrodes in solid-state lithium secondary batteries

    SciTech Connect

    Novak, P.; Inganas, O.; Bjorklund, R.

    1987-06-01

    The authors have developed composite polymer electrodes for use in all solid-state batteries in combination with Li. The composite is formed from water soluble polypyrrole which is combined with the solid polymer electrolyte polyethylene oxide. The composite electrode shows enhanced coulombic capacity as compared to an electrode composed only of the electroactive material, polypyrrole. Coulombic efficiency is good (90-95%) and energy efficiency is acceptable (80-85%) in galvanostatic studies. Charge retention is rather poor due to self-discharge. They have obtained proof that the electroactivity is due to polypyrrole, through the use of in situ spectroelectrochemical studies. They have characterized the composite electrode using scanning electron microscopy and conductive measurements.

  1. Sulfur tolerant composite cermet electrodes for solid oxide electrochemical cells

    DOEpatents

    Isenberg, Arnold O.

    1987-01-01

    An electrochemical apparatus is made containing an exterior electrode bonded to the exterior of a tubular, solid, oxygen ion conducting electrolyte where the electrolyte is also in contact with an interior electrode, said exterior electrode comprising particles of an electronic conductor contacting the electrolyte, where a ceramic metal oxide coating partially surrounds the particles and is bonded to the electrolyte, and where a coating of an ionic-electronic conductive material is attached to the ceramic metal oxide coating and to the exposed portions of the particles.

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

    NASA Astrophysics Data System (ADS)

    Yoon, Taek Han; Park, Yong Joon

    2012-01-01

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

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

    PubMed Central

    2012-01-01

    A carbon nanotube [CNT]/Co3O4 composite is introduced as a catalyst for the air electrode of lithium-air [Li/air] batteries. Co3O4 nanoparticles are successfully attached to the sidewall of the CNT by a hydrothermal method. A high discharge capacity and a low overvoltage indicate that the CNT/Co3O4 composite is a very promising catalyst for the air electrode of Li/air batteries. PMID:22222030

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

    PubMed

    Yoon, Taek Han; Park, Yong Joon

    2012-01-01

    A carbon nanotube [CNT]/Co3O4 composite is introduced as a catalyst for the air electrode of lithium-air [Li/air] batteries. Co3O4 nanoparticles are successfully attached to the sidewall of the CNT by a hydrothermal method. A high discharge capacity and a low overvoltage indicate that the CNT/Co3O4 composite is a very promising catalyst for the air electrode of Li/air batteries. PMID:22222030

  5. Hierarchically ordered mesoporous carbon/graphene composites as supercapacitor electrode materials.

    PubMed

    Song, Yanjie; Li, Zhu; Guo, Kunkun; Shao, Ting

    2016-08-25

    Hierarchically ordered mesoporous carbon/graphene (OMC/G) composites have been fabricated by means of a solvent-evaporation-induced self-assembly (EISA) method. The structures of these composites are characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy and nitrogen adsorption-desorption at 77 K. These results indicate that OMC/G composites possess the hierarchically ordered hexagonal p6mm mesostructure with the lattice unit parameter and pore diameter close to 10 nm and 3 nm, respectively. The specific surface area of OMC/G composites after KOH activation is high up to 2109.2 m(2) g(-1), which is significantly greater than OMC after activation (1474.6 m(2) g(-1)). Subsequently, the resulting OMC/G composites as supercapacitor electrode materials exhibit an outstanding capacitance as high as 329.5 F g(-1) in 6 M KOH electrolyte at a current density of 0.5 A g(-1), which is much higher than both OMC (234.2 F g(-1)) and a sample made by mechanical mixing of OMC with graphene (217.7 F g(-1)). In addition, the obtained OMC/G composites display good cyclic stability, and the final capacitance retention is approximately 96% after 5000 cycles. These ordered mesopores in the OMC/G composites are beneficial to the accessibility and rapid diffusion of the electrolyte, while graphene in OMC/G composites can also facilitate the transport of electrons during the processes of charging and discharging owing to its high conductivity, thereby leading to an excellent energy storage performance. The method demonstrated in this work would open up a new route to design and develop graphene-based architectures for supercapacitor applications. PMID:27523568

  6. Composition suitable for use as inert electrode having good electrical conductivity and mechanical properties

    DOEpatents

    Ray, S.P.; Rapp, R.A.

    1984-06-12

    An improved inert electrode composition is suitable for use as an inert electrode in the production of metals such as aluminum by the electrolytic reduction of metal oxide or metal salt dissolved in a molten salt bath. The composition comprises one or more metals or metal alloys and metal compounds which may include oxides of the metals comprising the alloy. The alloy and metal compounds are interwoven in a network which provides improved electrical conductivity and mechanical strength while preserving the level of chemical inertness necessary for such an electrode to function satisfactorily. 8 figs.

  7. Carbon composite micro- and nano-tubes-based electrodes for detection of nucleic acids

    PubMed Central

    2011-01-01

    The first aim of this study was to fabricate vertically aligned multiwalled carbon nanotubes (MWCNTs). MWCNTs were successfully prepared by using plasma enhanced chemical vapour deposition. Further, three carbon composite electrodes with different content of carbon particles with various shapes and sizes were prepared and tested on measuring of nucleic acids. The dependences of adenine peak height on the concentration of nucleic acid sample were measured. Carbon composite electrode prepared from a mixture of glassy and spherical carbon powder and MWCNTs had the highest sensitivity to nucleic acids. Other interesting result is the fact that we were able to distinguish signals for all bases using this electrode. PMID:21711910

  8. Composition suitable for use as inert electrode having good electrical conductivity and mechanical properties

    DOEpatents

    Ray, Siba P.; Rapp, Robert A.

    1984-01-01

    An improved inert electrode composition is suitable for use as an inert electrode in the production of metals such as aluminum by the electrolytic reduction of metal oxide or metal salt dissolved in a molten salt bath. The composition comprises one or more metals or metal alloys and metal compounds which may include oxides of the metals comprising the alloy. The alloy and metal compounds are interwoven in a network which provides improved electrical conductivity and mechanical strength while preserving the level of chemical inertness necessary for such an electrode to function satisfactorily.

  9. Carbon composite micro- and nano-tubes-based electrodes for detection of nucleic acids.

    PubMed

    Prasek, Jan; Huska, Dalibor; Jasek, Ondrej; Zajickova, Lenka; Trnkova, Libuse; Adam, Vojtech; Kizek, Rene; Hubalek, Jaromir

    2011-01-01

    The first aim of this study was to fabricate vertically aligned multiwalled carbon nanotubes (MWCNTs). MWCNTs were successfully prepared by using plasma enhanced chemical vapour deposition. Further, three carbon composite electrodes with different content of carbon particles with various shapes and sizes were prepared and tested on measuring of nucleic acids. The dependences of adenine peak height on the concentration of nucleic acid sample were measured. Carbon composite electrode prepared from a mixture of glassy and spherical carbon powder and MWCNTs had the highest sensitivity to nucleic acids. Other interesting result is the fact that we were able to distinguish signals for all bases using this electrode. PMID:21711910

  10. Inorganic composites for space applications

    NASA Technical Reports Server (NTRS)

    Malmendier, J. W.

    1984-01-01

    The development of inorganic composite materials for space applications is reviewed. The composites do not contain any organic materials, and therefore, are not subject to degradation by ultraviolet radiation, volatilization of constituents, or embrittlement at low temperatures. The composites consist of glass, glass/ceramics or ceramic matrices, reinforced by refractory whiskers or fibers. Such composites have the low thermal expansion, refractories, chemical stability and other desirable properties usually associated with the matrix materials. The composites also have a degree of toughness which is extraordinary for refractory inorganic materials.

  11. Ferrocene-functionalized graphene electrode for biosensing applications.

    PubMed

    Rabti, Amal; Mayorga-Martinez, Carmen C; Baptista-Pires, Luis; Raouafi, Noureddine; Merkoçi, Arben

    2016-07-01

    A novel ferrocene-functionalized reduced graphene oxide (rGO)-based electrode is proposed. It was fabricated by the drop casting of ferrocene-functionalized graphene onto polyester substrate as the working electrode integrated within screen-printed reference and counter electrodes. The ferrocene-functionalized rGO has been fully characterized using FTIR, XPS, contact angle measurements, SEM and TEM microscopy, and cyclic voltammetry. The XPS and EDX analysis showed the presence of Fe element related to the introduced ferrocene groups, which is confirmed by a clear CV signal at ca. 0.25 V vs. Ag/AgCl (0.1 KCl). Mediated redox catalysis of H2O2 and bio-functionalization with glucose oxidase for glucose detection were achieved by the bioelectrode providing a proof for potential biosensing applications. PMID:27216390

  12. Mixed-phase bismuth ferrite nanoflake electrodes for supercapacitor application

    NASA Astrophysics Data System (ADS)

    Jadhav, Vijaykumar V.; Zate, Manohar K.; Liu, Shude; Naushad, Mu.; Mane, Rajaram S.; Hui, K. N.; Han, Sung-Hwan

    2016-04-01

    Nanoflake bismuth ferrite thin film was synthesized by means of electrodeposition technique at room temperature. The morphology and phase evaluation of the synthesized electrode were analyzed using scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and surface wettability techniques. Specifically, the bismuth ferrite nanoflake electrode exhibited high specific capacitance of 72.2 F g-1 at a current density of 1 A g-1, and high rate capability with 37 % retention of capacitance even up to 20A g-1, and excellent cycling stability with 82.8 % retention of the initial capacitance after 1500 charge/discharge cycles, supporting that the bismuth ferrite thin-film electrode could be a potential candidate for supercapacitor application.

  13. Metal/Diamond Composite Thin-Film Electrodes: New Carbon Supported Catalytic Electrodes

    SciTech Connect

    Greg M. Swain, PI

    2009-03-10

    The DOE-funded research conducted by the Swain group was focused on (i) understanding structure-function relationships at boron-doped diamond thin-film electrodes, (ii) understanding metal phase formation on diamond thin films and developing electrochemical approaches for producing highly dispersed electrocatalyst particles (e.g., Pt) of small nominal particle size, (iii) studying the electrochemical activity of the electrocatalytic electrodes for hydrogen oxidation and oxygen reduction and (iv) conducting the initial synthesis of high surface area diamond powders and evaluating their electrical and electrochemical properties when mixed with a Teflon binder. (Note: All potentials are reported versus Ag/AgCl (sat'd KCl) and cm{sup 2} refers to the electrode geometric area, unless otherwise stated).

  14. Active C4 Electrodes for Local Field Potential Recording Applications.

    PubMed

    Wang, Lu; Freedman, David; Sahin, Mesut; Ünlü, M Selim; Knepper, Ronald

    2016-01-01

    Extracellular neural recording, with multi-electrode arrays (MEAs), is a powerful method used to study neural function at the network level. However, in a high density array, it can be costly and time consuming to integrate the active circuit with the expensive electrodes. In this paper, we present a 4 mm × 4 mm neural recording integrated circuit (IC) chip, utilizing IBM C4 bumps as recording electrodes, which enable a seamless active chip and electrode integration. The IC chip was designed and fabricated in a 0.13 μm BiCMOS process for both in vitro and in vivo applications. It has an input-referred noise of 4.6 μV rms for the bandwidth of 10 Hz to 10 kHz and a power dissipation of 11.25 mW at 2.5 V, or 43.9 μW per input channel. This prototype is scalable for implementing larger number and higher density electrode arrays. To validate the functionality of the chip, electrical testing results and acute in vivo recordings from a rat barrel cortex are presented. PMID:26861324

  15. Active C4 Electrodes for Local Field Potential Recording Applications

    PubMed Central

    Wang, Lu; Freedman, David; Sahin, Mesut; Ünlü, M. Selim; Knepper, Ronald

    2016-01-01

    Extracellular neural recording, with multi-electrode arrays (MEAs), is a powerful method used to study neural function at the network level. However, in a high density array, it can be costly and time consuming to integrate the active circuit with the expensive electrodes. In this paper, we present a 4 mm × 4 mm neural recording integrated circuit (IC) chip, utilizing IBM C4 bumps as recording electrodes, which enable a seamless active chip and electrode integration. The IC chip was designed and fabricated in a 0.13 μm BiCMOS process for both in vitro and in vivo applications. It has an input-referred noise of 4.6 μVrms for the bandwidth of 10 Hz to 10 kHz and a power dissipation of 11.25 mW at 2.5 V, or 43.9 μW per input channel. This prototype is scalable for implementing larger number and higher density electrode arrays. To validate the functionality of the chip, electrical testing results and acute in vivo recordings from a rat barrel cortex are presented. PMID:26861324

  16. Effects of reversible chemical reaction on Li diffusion and stresses in spherical composition-gradient electrodes

    SciTech Connect

    Li, Yong; Zhang, Kai; Zheng, Bailin Zhang, Xiaoqian; Wang, Qi

    2015-06-28

    Composition-gradient electrode materials have been proven to be one of the most promising materials in lithium-ion battery. To study the mechanism of mechanical degradation in spherical composition-gradient electrodes, the finite deformation theory and reversible chemical theory are adopted. In homogeneous electrodes, reversible electrochemical reaction may increase the magnitudes of stresses. However, reversible electrochemical reaction has different influences on stresses in composition-gradient electrodes, resulting from three main inhomogeneous factors—forward reaction rate, backward reaction rate, and reaction partial molar volume. The decreasing transition form of forward reaction rate, increasing transition form of backward reaction rate, and increasing transition form of reaction partial molar volume can reduce the magnitudes of stresses. As a result, capacity fading and mechanical degradation are reduced by taking advantage of the effects of inhomogeneous factors.

  17. Spray-Coated Multiwalled Carbon Nanotube Composite Electrodes for Thermal Energy Scavenging Electrochemical Cells.

    PubMed

    Holubowitch, Nicolas E; Landon, James; Lippert, Cameron A; Craddock, John D; Weisenberger, Matthew C; Liu, Kunlei

    2016-08-31

    Spray-coated multiwalled carbon nanotube/poly(vinylidene fluoride) (MWCNT/PVDF) composite electrodes, scCNTs, with varying CNT compositions (2 to 70 wt %) are presented for use in a simple thermal energy-scavenging cell (thermocell) based on the ferro/ferricyanide redox couple. Their utility for direct thermal-to-electrical energy conversion is explored at various temperature differentials and cell orientations. Performance is compared to that of buckypaper, a 100% CNT sheet material used as a benchmark electrode in thermocell research. The 30 to 70 wt % scCNT composites give the highest power output by electrode area-seven times greater than buckypaper at ΔT = 50 °C. CNT utilization is drastically enhanced in our electrodes, reaching 1 W gCNT(-1) compared to 0.036 W gCNT(-1) for buckypaper. Superior performance of our spray-coated electrodes is attributed to both wettability with better use of a large portion of electrochemically active CNTs and minimization of ohmic and thermal contact resistances. Even composites with as low as 2 wt % CNTs are still competitive with prior art. The MWCNT/PVDF composites developed herein are inexpensive, scalable, and serve a general need for CNT electrode optimization in next-generation devices. PMID:27510029

  18. Arsenic removal from groundwater using low-cost carbon composite electrodes for capacitive deionization.

    PubMed

    Lee, Ju-Young; Chaimongkalayon, Nantanee; Lim, Jinho; Ha, Heung Yong; Moon, Seung-Hyeon

    2016-01-01

    Affordable carbon composite electrodes were developed to treat low-concentrated groundwater using capacitive deionization (CDI). A carbon slurry prepared using activated carbon powder (ACP), poly(vinylidene fluoride), and N-methyl-2-pyrrolidone was employed as a casting solution to soak in a low-cost porous substrate. The surface morphology of the carbon composite electrodes was investigated using a video microscope and scanning electron microscopy. The capacitance and electrical conductivity of the carbon composite electrodes were then examined using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), respectively. According to the CV and EIS measurements, the capacitances and electrical conductivities of the carbon composite electrodes were in the range of 8.35-63.41 F g(-1) and 0.298-0.401 S cm(-1), respectively, depending on ACP contents. A CDI cell was assembled with the carbon composite electrodes instead of with electrodes and current collectors. The arsenate removal test included an investigation of the optimization of several important operating parameters, such as applied voltage and solution pH, and it achieved 98.8% removal efficiency using a 1 mg L(-1) arsenate solution at a voltage of 2 V and under a pH 9 condition. PMID:27332854

  19. Copper-substituted perovskite compositions for solid oxide fuel cell cathodes and oxygen reduction electrodes in other electrochemical devices

    DOEpatents

    Rieke, Peter C.; Coffey, Gregory W.; Pederson, Larry R.; Marina, Olga A.; Hardy, John S.; Singh, Prabhaker; Thomsen, Edwin C.

    2010-07-20

    The present invention provides novel compositions that find advantageous use in making electrodes for electrochemical cells. Also provided are electrochemical devices that include active oxygen reduction electrodes, such as solid oxide fuel cells, sensors, pumps and the like. The compositions comprises a copper-substituted ferrite perovskite material. The invention also provides novel methods for making and using the electrode compositions and solid oxide fuel cells and solid oxide fuel cell assemblies having cathodes comprising the compositions.

  20. Composite structural materials. [aircraft applications

    NASA Technical Reports Server (NTRS)

    Ansell, G. S.; Loewy, R. G.; Wiberley, S. E.

    1981-01-01

    The development of composite materials for aircraft applications is addressed with specific consideration of physical properties, structural concepts and analysis, manufacturing, reliability, and life prediction. The design and flight testing of composite ultralight gliders is documented. Advances in computer aided design and methods for nondestructive testing are also discussed.

  1. Surface Modification of Silver Nanowires for Morphology and Processing Control in Composite Transparent Electrodes.

    PubMed

    Liang, Zhiming; Graham, Kenneth R

    2015-10-01

    Silver nanowires are attractive components for a number of materials and applications, including silver nanowire (AgNW)-polymer composites, electrically conductive coatings, and transparent electrodes. In this manuscript, the ability of thiols with hydrophobic to ionic end groups to bind to AgNW surfaces is investigated, followed by how the polarity of the surface modifying thiol influences the morphological and electrical properties of both AgNW/PEDOT:PSS blend films and pure AgNW networks. Utilizing surface modification of AgNWs with sodium 3-mercapto-1-propanesulfonate (MPS), morphologically homogeneous AgNW/PEDOT:PSS thin films with an order of magnitude lower sheet resistance at similar transmittance values than unmodified AgNWs are obtained with a one-step processing method. Brief optimization of MPS-AgNW/PEDOT:PSS blends yields a sheet resistance of 22.6 Ω/□ at 81.4% transmittance. PMID:26389535

  2. Electroanalytical applications of screen-printable surfactant-induced sol-gel graphite composites

    DOEpatents

    Guadalupe, Ana R.; Guo, Yizhu

    2001-05-15

    A process for preparing sol-gel graphite composite electrodes is presented. This process preferably uses the surfactant bis(2-ethylhexyl) sulfosuccinate (AOT) and eliminates the need for a cosolvent, an acidic catalyst, a cellulose binder and a thermal curing step from prior art processes. Fabrication of screen-printed electrodes by this process provides a simple approach for electroanalytical applications in aqueous and nonaqueous solvents. Examples of applications for such composite electrodes produced from this process include biochemical sensors such as disposable, single-use glucose sensors and ligand modified composite sensors for metal ion sensitive sensors.

  3. Graphene-MoS2 nanosheet composites as electrodes for dye sensitised solar cells

    NASA Astrophysics Data System (ADS)

    Lynch, Peter; Khan, Umar; Harvey, Andrew; Ahmed, Iftikhar; Coleman, Jonathan N.

    2016-03-01

    Replacing the platinum counter electrode in dye-senstized solar cells with a cheaper material has attracted much attention recently. Graphene, graphene oxide and other 2-dimensional materials have received significant attention. Here we demonstrate the dependence of device parameters on the thickness of counter electrodes formed from porous, disordered arrays of liquid-exfoliated graphene nanosheets. We find device efficiency to saturate at a counter electrode thickness of ∼400 nm. Such optimised counter electrodes can be improved further by adding MoS2 nanosheets to the graphene electrode. By measuring the dependence of device parameters on the composition of mixed graphene/MoS2 electrodes, we show that adding ∼10 wt% MoS2 nanosheets to a graphene counter electrode improves performance and can result in a cell efficiency of ∼95% of that achieved using a platinum electrode. This data is consistent with the MoS2 nanosheets being somewhat better catalysts than the graphene nanosheets. However, the graphene nanosheets are required to render the electrode conductive. More detailed analysis suggests the better performance of the MoS2 nanosheets to be mostly down to their smaller size.

  4. Si composite electrode with Li metal doping for advanced lithium-ion battery

    SciTech Connect

    Liu, Gao; Xun, Shidi; Battaglia, Vincent

    2015-12-15

    A silicon electrode is described, formed by combining silicon powder, a conductive binder, and SLMP.TM. powder from FMC Corporation to make a hybrid electrode system, useful in lithium-ion batteries. In one embodiment the binder is a conductive polymer such as described in PCT Published Application WO 2010/135248 A1.

  5. Synthesis of NiMnO3/C nano-composite electrode materials for electrochemical capacitors

    NASA Astrophysics Data System (ADS)

    Kakvand, Pejman; Safi Rahmanifar, Mohammad; El-Kady, Maher F.; Pendashteh, Afshin; Kiani, Mohammad Ali; Hashami, Masumeh; Najafi, Mohsen; Abbasi, Ali; Mousavi, Mir F.; Kaner, Richard B.

    2016-08-01

    Demand for high-performance energy storage materials has motivated research activities to develop nano-engineered composites that benefit from both high-rate and high-capacitance materials. Herein, NiMnO3 (NMO) nanoparticles have been synthesized through a facile co-precipitation method. As-prepared NMO samples are then employed for the synthesis of nano-composites with graphite (Gr) and reduced graphene oxide (RGO). Various samples, including pure NMO, NMO-graphite blend, as well as NMO/Gr and NMO/RGO nano-composites have been electrochemically investigated as active materials in supercapacitors. The NMO/RGO sample exhibited a high specific capacitance of 285 F g‑1 at a current density of 1 A g‑1, much higher than the other samples (237 F g‑1 for NMO/Gr, 170 F g‑1 for NMO-Gr and 70 F g‑1 for NMO). Moreover, the NMO/RGO nano-composite has shown excellent cycle stability with a 93.5% capacitance retention over 1000 cycles at 2 A g‑1 and still delivered around 87% of its initial capacitance after cycling for 4000 cycles. An NMO/RGO composite was assessed in practical applications by assembling NMO/RGO//NMO/RGO symmetric devices, exhibiting high specific energy (27.3 Wh kg‑1), high specific power (7.5 kW kg‑1), and good cycle stability over a broad working voltage of 1.5 V. All the obtained results demonstrate the promise of NMO/RGO nano-composite as a high-performance electrode material for supercapacitors.

  6. Synthesis of NiMnO3/C nano-composite electrode materials for electrochemical capacitors.

    PubMed

    Kakvand, Pejman; Rahmanifar, Mohammad Safi; El-Kady, Maher F; Pendashteh, Afshin; Kiani, Mohammad Ali; Hashami, Masumeh; Najafi, Mohsen; Abbasi, Ali; Mousavi, Mir F; Kaner, Richard B

    2016-08-01

    Demand for high-performance energy storage materials has motivated research activities to develop nano-engineered composites that benefit from both high-rate and high-capacitance materials. Herein, NiMnO3 (NMO) nanoparticles have been synthesized through a facile co-precipitation method. As-prepared NMO samples are then employed for the synthesis of nano-composites with graphite (Gr) and reduced graphene oxide (RGO). Various samples, including pure NMO, NMO-graphite blend, as well as NMO/Gr and NMO/RGO nano-composites have been electrochemically investigated as active materials in supercapacitors. The NMO/RGO sample exhibited a high specific capacitance of 285 F g(-1) at a current density of 1 A g(-1), much higher than the other samples (237 F g(-1) for NMO/Gr, 170 F g(-1) for NMO-Gr and 70 F g(-1) for NMO). Moreover, the NMO/RGO nano-composite has shown excellent cycle stability with a 93.5% capacitance retention over 1000 cycles at 2 A g(-1) and still delivered around 87% of its initial capacitance after cycling for 4000 cycles. An NMO/RGO composite was assessed in practical applications by assembling NMO/RGO//NMO/RGO symmetric devices, exhibiting high specific energy (27.3 Wh kg(-1)), high specific power (7.5 kW kg(-1)), and good cycle stability over a broad working voltage of 1.5 V. All the obtained results demonstrate the promise of NMO/RGO nano-composite as a high-performance electrode material for supercapacitors. PMID:27324723

  7. Design and synthesis of polymer, carbon and composite electrodes for high energy and high power supercapacitors

    NASA Astrophysics Data System (ADS)

    Arcila Velez, Margarita Rosa

    ordered structure of the VACNTs showed superior performance compared to randomly oriented CNTs. To increase the energy density, the second approach was taken, by combining pre-synthesized conducting polymers (CPs) and carbon nanotubes (CNTs) using a facile scalable dispersion filtration method to produce free-standing electrodes. Composites with the three main CPs were prepared, analyzed in various electrolytes, and their performance was comparable with polymer/ CNT films prepared with more complex techniques such as in-situ polymerization and pellet pressing. Then, based on the idea that the quinone molecules present in lignin store charge by undergoing a 2 proton, 2 electron redox reaction, a composite between polypyrrole, a stable conducting polymer, and the prototypical molecule p-benzoquinone was fabricated by electropolymerization of pyrrole in the presence of the redox molecule. A significant increase in capacitance and capacity was obtained with respect to polypyrrole films. Furthermore, an important obstacle in the application of CPs in SCs is the lack of easily reduced (n-dopable) polymers. Poly(aminoanthraquinone) (PAQ) is a conjugated polymer that shows electroactivity in the negative potential range of 0 to -2 V, due to the redox moieties of the polymer. PAQ was electropolymerized on free-standing CNT films and its performance as anode for SCs was studied. The materials and processing techniques described in this dissertation are useful to further develop high power/high energy electrodes for SCs.

  8. Low-Temperature Solution Processable Electrodes for Piezoelectric Sensors Applications

    NASA Astrophysics Data System (ADS)

    Tuukkanen, Sampo; Julin, Tuomas; Rantanen, Ville; Zakrzewski, Mari; Moilanen, Pasi; Lupo, Donald

    2013-05-01

    Piezoelectric thin-film sensors are suitable for a wide range of applications from physiological measurements to industrial monitoring systems. The use of flexible materials in combination with high-throughput printing technologies enables cost-effective manufacturing of custom-designed, highly integratable piezoelectric sensors. This type of sensor can, for instance, improve industrial process control or enable the embedding of ubiquitous sensors in our living environment to improve quality of life. Here, we discuss the benefits, challenges and potential applications of piezoelectric thin-film sensors. The piezoelectric sensor elements are fabricated by printing electrodes on both sides of unmetallized poly(vinylidene fluoride) film. We show that materials which are solution processable in low temperatures, biocompatible and environmental friendly are suitable for use as electrode materials in piezoelectric sensors.

  9. Graphene-epoxy composite electrode fabricated by in situ polycondensation for enhanced amperometric detection in capillary electrophoresis.

    PubMed

    Tang, Dengfeng; Ma, Guo; Zhang, Luyan; Chen, Gang

    2013-11-01

    This report describes the development and application of a novel graphene-epoxy composite electrode as a sensitive amperometric detector of capillary electrophoresis. The composite electrode was fabricated on the basis of the in situ polycondensation of a mixture of graphene and 1,2-ethanediamine-containing bisphenol A epoxy resin in the inner bore of a piece of fused silica capillary under heat. The structure of the material was investigated by scanning electron microscopy, thermogravimetric analysis, X-ray diffraction, and Fourier transform infrared spectroscopy. The results indicated that graphene sheets were well dispersed and interconnected throughout the composite to form an electrically conductive network. The performance of this unique electrode was demonstrated by separating and detecting two naturally occurring phenolic compounds in rosemary in combination with capillary electrophoresis. The graphene-based detector offered significantly lower operating potentials, higher sensitivity, satisfactory resistance to surface fouling, and lower expense of operation, indicating great promise for a wide range of applications. PMID:24119752

  10. RuO2/Graphene composites for super-capacitor electrodes

    NASA Astrophysics Data System (ADS)

    Amir, Fatima; Ramlall, Tariq; Forest, Rebecca

    2013-03-01

    Metal oxides/graphene composites show significant improvement in their electrochemical proprieties compared to their individual constituents, such as high capacity, high rate capability and excellent cycling stability. Ruthenium dioxide (RuO2) has been recognized as an important electrode material for water electrolysis, oxygen reduction, and super-capacitors. A crucial aspect of all these applications is their structural, morphological and electrical properties. We have synthesized RuO2 from hydrolysis and oxidation of ruthenium tri-chloride RuCl3, which we physically mixed to graphene and used to coat tungsten substrates. For comparison, we also have deposited commercial RuO2 hydrate mixed with graphene on tungsten. The samples were then annealed at different temperatures. The effect of temperature has been studied in detail. Surface morphology analysis using a scanning electron microscope (SEM) shows smaller grain size at temperatures higher than 180 C. Structural properties obtained by using x-ray diffraction revealed an amorphous structure at temperatures lower than 180 C. The supercapacitance of the RuO2/graphene electrode is found to be dependent on the surface morphology. This project was supported by the Clare Booth Luce Foundation

  11. Fabrication of β-cyclodextrin-coated poly (diallyldimethylammonium chloride)-functionalized graphene composite film modified glassy carbon-rotating disk electrode and its application for simultaneous electrochemical determination colorants of sunset yellow and tartrazine.

    PubMed

    Ye, Xiaoliang; Du, Yongling; Lu, Daban; Wang, Chunming

    2013-05-24

    We proposed a green and facile approach for the synthesis of β-cyclodextrin-coated poly(diallyldimethylammonium chloride)-functionalized graphene composite film (β-CD-PDDA-Gr) by using L-ascorbic acid (L-AA) as the reducing agent at room temperature. The β-CD-PDDA-Gr composite film modified glassy carbon-rotating disk electrode (GC-RDE) was then developed for the sensitive simultaneous determination of two synthetic food colorants: sunset yellow (SY) and tartrazine (TT). By cyclic voltammetry (CV), the peak currents of SY and TT increased obviously on the developed electrochemical sensor. The kinetic parameters, such as diffusion coefficient D and standard heterogeneous rate constant kb, were estimated by linear sweep voltammetry (LSV). Under the optimal conditions, the differential pulse voltammetry (DPV) signals of SY and TT on the β-CD-PDDA-Gr modified GC-RDE were significantly enhanced. The enhanced anodic peak currents represented the excellent analytical performance of simultaneous detection of SY and TT in the range of 5.0×10(-8) to 2.0×10(-5) mol L(-1), with a low limit of detection (LOD) of 1.25×10(-8) mol L(-1) for SY and 1.43×10(-8) mol L(-1) for TT (SN(-1)=3). This proposed method displayed outstanding selectivity, good stability and acceptable repeatability and reproducibility, and also has been used to simultaneously determine SY and TT in some commercial soft drinks with satisfactory results. The obtained results were compared to HPLC of analysis for those two colorants and no significant differences were found. By the treatment of the experimental data, the electrochemical reaction mechanisms of SY and TT both involved a one-electron-one-proton-transfer process. PMID:23663668

  12. Critical roles of binders and formulation at multiscales of silicon-based composite electrodes

    NASA Astrophysics Data System (ADS)

    Mazouzi, D.; Karkar, Z.; Reale Hernandez, C.; Jimenez Manero, P.; Guyomard, D.; Roué, L.; Lestriez, B.

    2015-04-01

    In this review we try to shed a comprehensive understanding on the influence of the different parameters of the formulation of silicon-based composite electrode on its cyclability, i.e. the binder, the conductive additives, the current collector, the electrode porosity and solid loading, in view of a more rational assessment of the relevancy of these parameters for the battery technology. The reasons of the better efficiency of carboxymethyl cellulose and alternative new binders than PVdF are first addressed into details. The critical effects of the active mass loading and porosity on the cyclability are highlighted. Then the influence of the conductive additive type and current collector texture are discussed. Putting everything together shows that it is required to meticulously optimize all the different scales of the composite electrode to hopefully raise the performance of silicon-based electrode above that of graphite commercial ones.

  13. Biosensing applications of titanium dioxide coated graphene modified disposable electrodes.

    PubMed

    Kuralay, Filiz; Tunç, Selma; Bozduman, Ferhat; Oksuz, Lutfi; Oksuz, Aysegul Uygun

    2016-11-01

    In the present work, preparation of titanium dioxide coated graphene (TiO2/graphene) and the use of this nanocomposite modified electrode for electrochemical biosensing applications were detailed. The nanocomposite was prepared with radio frequency (rf) rotating plasma method which serves homogeneous distribution of TiO2 onto graphene. TiO2/graphene was characterized with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) analysis. Then, this nanocomposite was dissolved in phosphate buffer solution (pH 7.4) and modified onto disposable pencil graphite electrode (PGE) by dip coating for the investigation of the biosensing properties of the prepared electrode. TiO2/graphene modified PGE was characterized with SEM, EDS and cyclic voltammetry (CV). The sensor properties of the obtained surface were examined for DNA and DNA-drug interaction. The detection limit was calculated as 1.25mgL(-1) (n=3) for double-stranded DNA (dsDNA). RSD% was calculated as 2.4% for three successive determinations at 5mgL(-1) dsDNA concentration. Enhanced results were obtained compared to the ones obtained with graphene and unmodified (bare) electrodes. PMID:27591620

  14. Dispersion of Nanocrystalline Fe3O4 within Composite Electrodes: Insights on Battery-Related Electrochemistry.

    PubMed

    Bock, David C; Pelliccione, Christopher J; Zhang, Wei; Wang, Jiajun; Knehr, K W; Wang, Jun; Wang, Feng; West, Alan C; Marschilok, Amy C; Takeuchi, Kenneth J; Takeuchi, Esther S

    2016-05-11

    Aggregation of nanosized materials in composite lithium-ion-battery electrodes can be a significant factor influencing electrochemical behavior. In this study, aggregation was controlled in magnetite, Fe3O4, composite electrodes via oleic acid capping and subsequent dispersion in a carbon black matrix. A heat treatment process was effective in the removal of the oleic acid capping agent while preserving a high degree of Fe3O4 dispersion. Electrochemical testing showed that Fe3O4 dispersion is initially beneficial in delivering a higher functional capacity, in agreement with continuum model simulations. However, increased capacity fade upon extended cycling was observed for the dispersed Fe3O4 composites relative to the aggregated Fe3O4 composites. X-ray absorption spectroscopy measurements of electrodes post cycling indicated that the dispersed Fe3O4 electrodes are more oxidized in the discharged state, consistent with reduced reversibility compared with the aggregated sample. Higher charge-transfer resistance for the dispersed sample after cycling suggests increased surface-film formation on the dispersed, high-surface-area nanocrystalline Fe3O4 compared to the aggregated materials. This study provides insight into the specific effects of aggregation on electrochemistry through a multiscale view of mechanisms for magnetite composite electrodes. PMID:27096464

  15. A reduced graphene oxide/Co{sub 3}O{sub 4} composite for supercapacitor electrode

    SciTech Connect

    Xiang, Chengcheng; Li, Ming; Zhi, Mingjia; Manivannan, Ayyakkannu; Wu, Nianqiang

    2013-03-15

    20 nm sized Co{sub 3}O{sub 4} nanoparticles are in-situ grown on the chemically reduced graphene oxide (rGO) sheets to form a rGO-Co{sub 3}O{sub 4} composite during hydrothermal processing. The rGO-Co{sub 3}O{sub 4} composite is employed as the pseudocapacitor electrode in the 2 M KOH aqueous electrolyte solution. The rGOCo{sub 3}O{sub 4} composite electrode exhibits a specific capacitance of 472 F/g at a scan rate of 2 mV/s in a two-electrode cell. 82.6% of capacitance is retained when the scan rate increases to 100 mV/s. The rGOCo{sub 3}O{sub 4} composite electrode shows high rate capability and excellent long-term stability. It also exhibits high energy density at relatively high power density. The energy density reaches 39.0 Wh/kg at a power density of 8.3 kW/kg. The super performance of the composite electrode is attributed to the synergistic effects of small size and good redox activity of the Co{sub 3}O{sub 4} particles combined with high electronic conductivity of the rGO sheets.

  16. Dispersion of nanocrystalline Fe3O4 within composite electrodes: Insights on battery-related electrochemistry

    DOE PAGESBeta

    David C. Bock; Takeuchi, Kenneth J.; Pelliccione, Christopher J.; Zhang, Wei; Wang, Jiajun; Knehr, K. W.; Wang, Jun; Wang, Feng; West, Alan C.; Marschilok, Amy C.; et al

    2016-04-20

    Aggregation of nanosized materials in composite lithium-ion-battery electrodes can be a significant factor influencing electrochemical behavior. In this study, aggregation was controlled in magnetite, Fe3O4, composite electrodes via oleic acid capping and subsequent dispersion in a carbon black matrix. A heat treatment process was effective in the removal of the oleic acid capping agent while preserving a high degree of Fe3O4 dispersion. Electrochemical testing showed that Fe3O4 dispersion is initially beneficial in delivering a higher functional capacity, in agreement with continuum model simulations. However, increased capacity fade upon extended cycling was observed for the dispersed Fe3O4 composites relative to themore » aggregated Fe3O4 composites. X-ray absorption spectroscopy measurements of electrodes post cycling indicated that the dispersed Fe3O4 electrodes are more oxidized in the discharged state, consistent with reduced reversibility compared with the aggregated sample. Higher charge-transfer resistance for the dispersed sample after cycling suggests increased surface-film formation on the dispersed, high-surface-area nanocrystalline Fe3O4 compared to the aggregated materials. Furthermore, this study provides insight into the specific effects of aggregation on electrochemistry through a multiscale view of mechanisms for magnetite composite electrodes.« less

  17. [Research on treatment of high salt wastewater by the graphite and activated carbon fiber composite electrodes].

    PubMed

    Zhou, Gui-Zhong; Wang, Zhao-Feng; Wang, Xuan; Li, Wen-Qian; Li, Shao-Xiang

    2014-05-01

    High salinity wastewater is one of the difficulties in the field of wastewater treatment. As a new desalination technology, electrosorption technology has many advantages. This paper studied a new type of carbon-based electrodes, the graphite and activated carbon fiber composite electrodes. And the influencing factors of electrosorption and its desalination effect were investigated. The electrosorption device had optimal desalination effect when the voltage was 1. 6 V, the retention time was 60 min and the plate spacing was 1 cm. The graphite and activated carbon fiber composite electrodes were used to treat the black liquor of refined cotton and sodium copper chlorophyll wastewater to investigate its desalination effect. When the electrodes were used to treat the black liquor of refined cotton after acid treatment, the removal rate of conductivity and COD reached 58. 8% and 75. 6% respectively when 8 pairs of electrodes were used. And when the electrode was used to treat the sodium copper chlorophyll wastewater, the removal rate of conductivity and COD reached higher than 50. 0% and 13. 5% respectively when 6-8 pairs of electrodes were used. PMID:25055674

  18. Silver nanowire/polyaniline composite transparent electrode with improved surface properties

    SciTech Connect

    Kumar, A.B.V. Kiran; Jiang, Jianwei; Bae, Chang Wan; Seo, Dong Min; Piao, Longhai Kim, Sang-Ho

    2014-09-15

    Highlights: • AgNWs/PANI transparent electrode was prepared by layer-by-layer coating method. • The surface roughness of the electrode reached to 6.5 nm (root mean square). • The electrode had reasonable sheet resistance (25 Ω/□) and transmittance (83.5%). - Abstract: Silver nanowires (AgNWs) are as potential candidates to replace indium tin oxide (ITO) in transparent electrodes because of their preferred conducting and optical properties. However, their rough surface properties are not favorable for the fabrication of optoelectronic devices, such as displays and thin-film solar cells. In the present investigation, AgNWs/polyaniline composite transparent electrodes with better surface properties were successfully prepared. AgNWs were incorporated into polyaniline:polystyrene sulfonate (PANI:PSS) by layer-by-layer coating and mechanical pressing. PANI:PSS decreased the surface roughness of the AgNWs electrode by filling the gap of the random AgNWs network. The transparent composite electrode had decreased surface roughness (root mean square 6.5 nm) with reasonable sheet resistance (25 Ω/□) and transmittance (83.5%)

  19. Polyvinylpyrrolidone/polyvinyl butyral composite as a stable binder for castable supercapacitor electrodes in aqueous electrolytes

    NASA Astrophysics Data System (ADS)

    Aslan, M.; Weingarth, D.; Herbeck-Engel, P.; Grobelsek, I.; Presser, V.

    2015-04-01

    Mixtures of polyvinylpyrrolidone/polyvinyl butyral (PVP/PVB) are attractive binders for the preparation of carbon electrodes for aqueous electrolyte supercapacitors. The use of PVP/PVB offers several key advantages: They are soluble in ethanol and can be used to spray coat or drain cast activated carbon (AC) electrodes directly on a current collector. Infrared spectroscopy and contact angle measurements show that the PVP-to-PVB ratio determines the degree of binder hydrophilicity. Within our study, the most favorable performance was obtained for AC electrodes with a composition of AC + 1.5 mass% PVP + 6.0 mass% PVB; such electrodes were mechanically stabile and water resistant with a PVP release of less than 5% of total PVP while PVB itself is water insoluble. Compared to when using PVDF, the specific surface area (SSA) of the assembled electrodes was 10% higher, indicating a reduced pore blocking tendency. A good electrochemical performance was observed in different aqueous electrolytes for composite electrodes with the optimized binder composition: 160 F g-1 at 1 A g-1 for 1 M H2SO4 and 6 M KOH and 120 F g-1 for 1 M NaCl. The capacitance was slightly reduced by 2.5% after cycling to 1.2 V with 1.28 A g-1 in 1 M NaCl for 10,000 times.

  20. High Energy Density Asymmetric Supercapacitor Based on NiOOH/Ni3S2/3D Graphene and Fe3O4/Graphene Composite Electrodes

    PubMed Central

    Lin, Tsung-Wu; Dai, Chao-Shuan; Hung, Kuan-Chung

    2014-01-01

    The application of the composite of Ni3S2 nanoparticles and 3D graphene as a novel cathode material for supercapacitors is systematically investigated in this study. It is found that the electrode capacitance increases by up to 111% after the composite electrode is activated by the consecutive cyclic voltammetry scanning in 1 M KOH. Due to the synergistic effect, the capacitance and the diffusion coefficient of electrolyte ions of the activated composite electrode are ca. 3.7 and 6.5 times higher than those of the Ni3S2 electrode, respectively. Furthermore, the activated composite electrode exhibits an ultrahigh specific capacitance of 3296 F/g and great cycling stability at a current density of 16 A/g. To obtain the reasonable matching of cathode/anode electrodes, the composite of Fe3O4 nanoparticles and chemically reduced graphene oxide (Fe3O4/rGO) is synthesized as the anode material. The Fe3O4/rGO electrode exhibits the specific capacitance of 661 F/g at 1 A/g and excellent rate capability. More importantly, an asymmetric supercapacitor fabricated by two different composite electrodes can be operated reversibly between 0 and 1.6 V and obtain a high specific capacitance of 233 F/g at 5 mV/s, which delivers a maximum energy density of 82.5 Wh/kg at a power density of 930 W/kg. PMID:25449978

  1. Electrochemical studies on nanometal oxide-activated carbon composite electrodes for aqueous supercapacitors

    NASA Astrophysics Data System (ADS)

    Ho, Mui Yen; Khiew, Poi Sim; Isa, Dino; Chiu, Wee Siong

    2014-11-01

    In present study, the electrochemical performance of eco-friendly and cost-effective titanium oxide (TiO2)-based and zinc oxide-based nanocomposite electrodes were studied in neutral aqueous Na2SO3 electrolyte, respectively. The electrochemical properties of these composite electrodes were studied using cyclic voltammetry (CV), galvanostatic charge-discharge (CD) and electrochemical impedance spectroscopy (EIS). The experimental results reveal that these two nanocomposite electrodes achieve the highest specific capacitance at fairly low oxide loading onto activated carbon (AC) electrodes, respectively. Considerable enhancement of the electrochemical properties of TiO2/AC and ZnO/AC nanocomposite electrodes is achieved via synergistic effects contributed from the nanostructured metal oxides and the high surface area mesoporous AC. Cations and anions from metal oxides and aqueous electrolyte such as Ti4+, Zn2+, Na+ and SO32- can occupy some pores within the high-surface-area AC electrodes, forming the electric double layer at the electrode-electrolyte interface. Additionally, both TiO2 and ZnO nanoparticles can provide favourable surface adsorption sites for SO32- anions which subsequently facilitate the faradaic processes for pseudocapacitive effect. These two systems provide the low cost material electrodes and the low environmental impact electrolyte which offer the increased charge storage without compromising charge storage kinetics.

  2. Graphene as Transparent Electrodes: Fabrication and New Emerging Applications.

    PubMed

    Xu, Yuanhong; Liu, Jingquan

    2016-03-01

    Graphene has been regarded as a promising candidate for a new generation of transparent electrodes (TEs) due to its prominent characteristics including high optical transmittance, exceptional electronic transport, outstanding mechanical strength, and environmental stability. Comprehensive and critical insights into the latest advances in graphene-based TEs (GTEs) since, but not limited to 2013, are provided, with an emphasis on fabrication, modification, and versatile applications. Several emerging application areas not previously summarized, including electrochromic devices, supercapacitors, electrochemical and electrochemiluminescent sensors, are discussed in detail. The challenges and prospects in these fields are also addressed. PMID:26854030

  3. RuO2/MnO2 composite materials for high-performance supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Jianming, Lei; Xiaomei, Chen

    2015-08-01

    Ruthenium oxide and manganese oxide nanomaterials were respectively prepared by a sol-gel process and hydrothermal synthesis method. The morphologies and microstructures of the composite nanomaterials were characterized by SEM and XRD. Based on the cyclic voltammetry, electrochemical impedance spectroscopy and constant current charge-discharge techniques, the performances of the electrodes were investigated. The results show that the composite of manganese oxide and ruthenium oxide is beneficial to improve the impedance characteristic. The electrode with 60% (mass ratio) manganese oxide has a high specific capacitance of 438 F/g and a lower inner resistance of 0.304 Ω using 38% (mass ratio) H2SO4 solution. The capacitance retention of RuO2/MnO2 composite electrode was 92.5% after 300 cycles.

  4. Electrocatalytic Hydrogen Evolution from Molybdenum Sulfide-Polymer Composite Films on Carbon Electrodes.

    PubMed

    Lattach, Youssef; Deronzier, Alain; Moutet, Jean-Claude

    2015-07-29

    The design of more efficient catalytic electrodes remains an important objective for the development of water splitting electrolyzers. In this context a structured composite cathode material has been synthesized by electrodeposition of molybdenum sulfide (MoSx) into a poly(pyrrole-alkylammonium) matrix, previously coated onto carbon electrodes by oxidative electropolymerization of a pyrrole-alkylammonium monomer. The composite material showed an efficient electrocatalytic activity toward proton reduction and the hydrogen evolution reaction (HER). Data from Tafel plots have demonstrated that the electron transfer rate in the composite films is fast, in agreement with the high catalytic activity of this cathode material. Bulk electrolysis of acidic water at carbon foam electrodes modified with the composite have shown that the cathodes display a high catalytic activity and a reasonable operational stability, largely exceeding that of regular amorphous MoSx electrodeposited on naked carbon foam. The enhanced catalytic performances of the composite electrode material were attributed to the structuration of the composite, which led to a homogeneous distribution of the catalyst on the carbon foam network, as shown by SEM characterizations. PMID:26147828

  5. Enhanced photoelectrocatalytic activity for dye degradation by graphene-titania composite film electrodes.

    PubMed

    Wang, Peifang; Ao, Yanhui; Wang, Chao; Hou, Jun; Qian, Jin

    2012-07-15

    Graphene-titania composite film electrodes have been fabricated by a dip-coating method. Transmission electron microscopy (TEM) images show that the titania nanoparticles were dispersed uniformly, with only a little aggregation on the surface and edges of the graphene sheets. XRD analysis showed that the composite electrodes comprised the anatase phase of titania with just a little rutile phase. The photoelectrocatalytic activities of the as-prepared samples were investigated by studies of the degradation of Reactive Brilliant Red dye X-3B (C.I. reactive red 2). An enhancement of the photocurrents was observed using the graphene-titania composite electrodes, compared with pure titania film electrodes, under UV light irradiation. This improvement is attributed to the following two reasons: enhanced migration efficiency of the photo-induced electrons and enhanced adsorption activity of the dye molecules. In addition, we investigated the effects of graphene content and pH values on the photoelectrocatalytic activity of the as-prepared composite film electrodes. Results showed that there was an optimal amount of 5% (initial graphite oxide content). PMID:22579760

  6. State of health estimation in composite electrode lithium-ion cells

    NASA Astrophysics Data System (ADS)

    Bartlett, Alexander; Marcicki, James; Rhodes, Kevin; Rizzoni, Giorgio

    2015-06-01

    Electrochemical models of lithium-ion batteries have been increasingly considered for online state of health estimation. These models can more accurately predict cell performance than traditional circuit models and can better relate physical degradation mechanisms to changes in model parameters. However, examples of state of health estimation algorithms that are validated with experimental data are scarce in the literature, particularly for cells with a composite electrode. The individual electrode active materials in a composite electrode may degrade at different rates and according to different physical mechanisms, and online estimation of this degradation facilitates more robust knowledge of how battery performance changes over its life. In this paper we use a reduced-order electrochemical model for a composite LiMn2O4-LiNi1/3Mn1/3 Co1/3O2 (LMO-NMC) electrode cell for online estimation of active material loss. Experimental data collected from composite electrode half cells that were aged under constant current cycling are used in an extended Kalman filter to estimate model parameters associated with loss of each active material. The capacity loss predicted by the online estimates agrees well with the measured capacity loss. Additionally, a differential capacity analysis demonstrates that active materials lose capacity at a similar rate, the same conclusion obtained from the online estimation algorithm.

  7. TCO/Ag/TCO transparent electrodes for solar cells application

    NASA Astrophysics Data System (ADS)

    Boscarino, S.; Crupi, I.; Mirabella, S.; Simone, F.; Terrasi, A.

    2014-09-01

    Among transparent electrodes, transparent conductive oxides (TCO)/metal/TCO structures can achieve optical and electrical performances comparable to, or better than, single TCO layers and very thin metallic films. In this work, we report on thin multilayers based on aluminum zinc oxide (AZO), indium tin oxide (ITO) and Ag deposited by RF magnetron sputtering on soda lime glass at room temperature. The TCO/Ag/TCO structures with thicknesses of about 50/10/50 nm were deposited with all combinations of AZO and ITO as top and bottom layers. While the electrical conductivity is dominated by the Ag intralayer irrespective of the TCO nature, the optical transmissions show a dependence on the nature of the top and bottom TCOs, mainly due to the change in the reflectivity of the multilayers. Structural, electrical and optical properties are studied to optimize the structure for very thin transparent electrodes suitable for photovoltaic applications.

  8. 21 CFR 884.2675 - Fetal scalp circular (spiral) electrode and applicator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Fetal scalp circular (spiral) electrode and... Gynecological Monitoring Devices § 884.2675 Fetal scalp circular (spiral) electrode and applicator. (a) Identification. A fetal scalp circular (spiral) electrode and applicator is a device used to obtain a...

  9. 21 CFR 884.2675 - Fetal scalp circular (spiral) electrode and applicator.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Fetal scalp circular (spiral) electrode and... Gynecological Monitoring Devices § 884.2675 Fetal scalp circular (spiral) electrode and applicator. (a) Identification. A fetal scalp circular (spiral) electrode and applicator is a device used to obtain a...

  10. Characterization of copper manganite oxide-polypyrrole composite electrodes cathodically polarized in acidic medium

    SciTech Connect

    Marco, J.F.; Canto, M. del; Rios, E.; Gautier, J.L.

    2008-08-04

    We have studied the electrochemical behaviour induced by polarization in sandwich-type composite electrodes with the structure GC/PPy/PPy(Ox)/PPy where GC stands for glassy carbon, PPy for polypyrrole and Ox for Cu{sub 1.4}Mn{sub 1.6}O{sub 4} nanoparticles. The electrodes were polarized at -0.45 V/SCE in 0.15 M KCl aqueous solution at pH 2.2 either saturated in Ar or O{sub 2} at 25 deg. C. The changes occurring on these electrodes were studied using X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (EXAFS and XANES) techniques. In previous work we have shown that when the oxide particles are incorporated into the PPy matrix the Cu{sup +} present in the initial oxide suffers dismutation to give Cu{sup 2+} and metallic Cu. In this work we show that the polarized electrodes also reveal the presence of metallic Cu and Cu{sup 2+}. The data also show that the oxide particles embedded in the polarized electrodes contain Mn{sup 3+} and Mn{sup 4+}, although the Mn{sup 3+}/Mn{sup 4+} ratio is different from that found in the fresh electrodes. The Cl 2p XPS data show that in the electrode polarized in O{sub 2} there is an enhancement of the Cl covalent contribution that appears at 200.8 eV (which is already present in the fresh electrode although with a very small intensity). This result suggests that the oxygen reduction reaction leads to an increase of the OH{sup -} concentration inside the composite electrode that explains the charge transport in PPy at negative potentials.

  11. Poly(vinyl alcohol)/poly(vinyl chloride) composite polymer membranes for secondary zinc electrodes

    NASA Astrophysics Data System (ADS)

    Yang, Chun-Chen; Yang, Jen Ming; Wu, Cheng-Yeou

    A microporous composite polymer membrane composed of poly(vinyl alcohol) (PVA) and poly(vinyl chloride) (PVC), was prepared by a solution casting method and a partial dissolution process. The characteristic properties of microporous PVA/PVC composite polymer membranes containing 2.5-10 wt.% PVC polymers as fillers were characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM), capillary flow porometry (CFP), micro-Raman spectroscopy, dynamic mechanical analyzer (DMA) and the AC impedance method. The electrochemical properties of a secondary Zn electrode with the PVA/PVC composite polymer membrane were studied using the galvanostatic charge/discharge method. The PVA/PVC composite polymer membrane showed good thermal, mechanical and electrochemical properties. As a result, the PVA/PVC composite polymer membrane appears to be a good candidate for use on the secondary Zn electrodes.

  12. Plasma Sprayed Si Nano Composite Powders for Negative Electrode of Lithium Ion Batteries

    NASA Astrophysics Data System (ADS)

    Kaga, Mashiro; Hideshima, Tasuku; Kambara, Makoto

    The electrochemical performance of the Si nano composite powders produced by PS-PVD was analyzed with Li counter electrode. The PS-PVD powders have showed an improved capacity compared to the raw mg-Si as negative electrode. Furthermore composite powders produced with CH4 addition showed higher specific gravimetric capacities per Si active materials of 1200 mAh/g, compared to 1024 mAh/g for the powders without C, suggesting the effectiveness of C coating on to the primary nano-Si and SiC particle inclusion for reinforcement of the active materials.

  13. Preparation and photoelectrocatalytic performance of N-doped TiO2/NaY zeolite membrane composite electrode material.

    PubMed

    Cheng, Zhi-Lin; Han, Shuai

    2016-01-01

    A novel composite electrode material based on a N-doped TiO2-loaded NaY zeolite membrane (N-doped TiO2/NaY zeolite membrane) for photoelectrocatalysis was presented. X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible (UV-vis) and X-ray photoelectron spectroscopy (XPS) characterization techniques were used to analyze the structure of the N-doped TiO2/NaY zeolite membrane. The XRD and SEM results verified that the N-doped TiO2 nanoparticles with the size of ca. 20 nm have been successfully loaded on the porous stainless steel-supported NaY zeolite membrane. The UV-vis result showed that the N-doped TiO2/NaY zeolite membrane exhibited a more obvious red-shift than that of N-TiO2 nanoparticles. The XPS characterization revealed that the doping of N element into TiO2 was successfully achieved. The photoelectrocatalysis performance of the N-doped TiO2/NaY zeolite membrane composite electrode material was evaluated by phenol removal and also the effects of reaction conditions on the catalytic performance were investigated. Owing to exhibiting an excellent catalytic activity and good recycling stability, the N-doped TiO2/NaY zeolite membrane composite electrode material was of promising application for photoelectrocatalysis in wastewater treatment. PMID:26877029

  14. Carbon-Nanotube-Based Electrodes for Biomedical Applications

    NASA Technical Reports Server (NTRS)

    Li, Jun; Meyyappan, M.

    2008-01-01

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

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

    PubMed

    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. PMID:27455650

  16. Superior lithium storage performance using sequentially stacked MnO2/reduced graphene oxide composite electrodes.

    PubMed

    Kim, Sue Jin; Yun, Young Jun; Kim, Ki Woong; Chae, Changju; Jeong, Sunho; Kang, Yongku; Choi, Si-Young; Lee, Sun Sook; Choi, Sungho

    2015-04-24

    Hybrid nanostructures based on graphene and metal oxides hold great potential for use in high-performance electrode materials for next-generation lithium-ion batteries. Herein, a new strategy to fabricate sequentially stacked α-MnO2 /reduced graphene oxide composites driven by surface-charge-induced mutual electrostatic interactions is proposed. The resultant composite anode exhibits an excellent reversible charge/discharge capacity as high as 1100 mA h g(-1) without any traceable capacity fading, even after 100 cycles, which leads to a high rate capability electrode performance for lithium ion batteries. Thus, the proposed synthetic procedures guarantee a synergistic effect of multidimensional nanoscale media between one (metal oxide nanowire) and two dimensions (graphene sheet) for superior energy-storage electrodes. PMID:25845554

  17. A new modified conducting carbon composite electrode as sensor for ascorbate and biosensor for glucose.

    PubMed

    Barsan, Madalina M; Brett, Christopher M A

    2009-09-01

    A new carbon-based conducting composite has been developed as electrochemical sensor and biosensor for the amperometric detection of ascorbate and glucose. Electrocatalytic oxidation of ascorbate has been done successfully at unmodified cellulose acetate-graphite composite electrodes, the sensor being highly sensitive, selective and with a low detection limit at 0.0 V vs. SCE and was successfully applied for ascorbate determination in commercial fruit juice samples. An interference free glucose biosensor has also been developed, based on the immobilisation of glucose oxidase by cross-linking with glutaraldehyde on poly (neutral red) modified composite electrodes. The biosensor exhibits a higher sensitivity of 31.5+/-1.7 microA cm(-2) mM(-1) than other carbon-composite-based glucose biosensors, a detection limit of 20.3 microM and a very short response time. PMID:19349215

  18. A Method for Efficient Transmittance Spectrum Prediction of Transparent Composite Electrodes

    NASA Astrophysics Data System (ADS)

    Zhao, Zhao; Dhar, A.; Alford, T. L.

    2015-07-01

    The interest in indium-free transparent composite electrode (TCE), a thin metal layer embedded between two transparent metal oxide (TMO) layers resulting in TMO/metal/TMO composite structure, has grown recently with the advent of their high figures of merit and its potential application in photovoltaic applications. However, most of the work to date has focused on experimentally producing the best optically transmitting TCE. To better design TCEs and minimize experimental work, it would be useful to develop a model that predicts the optical transmission. In the current work, the transfer-matrix method is employed to calculate the transmittance spectrum of TCE. To validate this approach, the transmittance spectra of TiO2/Au/TiO2 and TiO2/Ag/TiO2 multilayer thin-film TCEs are calculated with use of extracted material parameters. The calculated transmittance spectrum of TiO2/Au/TiO2 matches the measured spectrum quite well. However, the calcualted transmittance of TiO2/Ag/TiO2 is higher than its measured transmittance. The presence of voids in the Ag film is probably responsible for the decreased transmittance of the TiO2/Ag/TiO2 sample, and the continuous Au film in TiO2/Au/TiO2 ensures a good agreement between transmittance prediction and measurement. Our approach is a reliable tool to predict the optical transmittance of TCE with continuous films, and it can efficiently expedite the selection from numerous possible combinations of transparent metal oxides and metals when developing TCEs for future photovoltaic applications. It can also serve as a convenient method to assess the continuity of embedded metal layer.

  19. Solid contact potassium selective electrodes for biomedical applications - a review.

    PubMed

    van de Velde, L; d'Angremont, E; Olthuis, W

    2016-11-01

    Ion-selective electrodes (ISE) are used in several biomedical applications, including laboratory sensing of potassium concentration in blood and urine samples. For on-site determination of potassium concentration and usage in other applications such as determination of extracellular potassium concentration, miniaturization of the sensors is required. To that extent, solid contacts have proven to be an adequate substitute of liquid contacts as inner layer for ion-to-electron transduction, allowing industrial production of miniaturized ISEs. This review paper covers relevant developments of solid-state ISEs in the past decade, critically compares current potassium ISEs and discusses future prospects for biomedical applications. Performances of three main types of solid contact materials in potassium sensing are compared, namely polypyrrole, polythiophenes and conducting nanomaterials. With these new materials, numerous improvements in stability, selectivity and time response of solid-state ISEs have been made. Current developments are new operational methods of sensing, flexible miniaturized sensors and multi-electrode designs able to measure electrolyte concentrations in one-drop blood samples or transmembrane ionic flows. PMID:27591587

  20. Electrode material comprising graphene-composite materials in a graphite network

    DOEpatents

    Kung, Harold H.; Lee, Jung K.

    2014-07-15

    A durable electrode material suitable for use in Li ion batteries is provided. The material is comprised of a continuous network of graphite regions integrated with, and in good electrical contact with a composite comprising graphene sheets and an electrically active material, such as silicon, wherein the electrically active material is dispersed between, and supported by, the graphene sheets.

  1. Nanostructured Composite Electrodes for Lithium Batteries (Final Technical Report)

    SciTech Connect

    Meilin Liu, James Gole

    2006-12-14

    The objective of this study was to explore new ways to create nanostructured electrodes for rechargeable lithium batteries. Of particular interests are unique nanostructures created by electrochemical deposition, etching and combustion chemical vapor deposition (CCVD). Three-dimensional nanoporous Cu6Sn5 alloy has been successfully prepared using an electrochemical co-deposition process. The walls of the foam structure are highly-porous and consist of numerous small grains. This represents a novel way of creating porous structures that allow not only fast transport of gas and liquid but also rapid electrochemical reactions due to high surface area. The Cu6Sn5 samples display a reversible capacity of {approx}400 mAhg-1. Furthermore, these materials exhibit superior rate capability. At a current drain of 10 mA/cm2(20C rate), the obtainable capacity was more than 50% of the capacity at 0.5 mA/cm2 (1C rate). Highly open and porous SnO2 thin films with columnar structure were obtained on Si/SiO2/Au substrates by CCVD. The thickness was readily controlled by the deposition time, varying from 1 to 5 microns. The columnar grains were covered by nanoparticles less than 20 nm. These thin film electrodes exhibited substantially high specific capacity. The reversible specific capacity of {approx}3.3 mAH/cm2 was demonstrated for up to 80 cycles at a charge/discharge rate of 0.3 mA/cm2. When discharged at 0.9 mA/cm2, the capacity was about 2.1 mAH/cm2. Tin dioxide box beams or tubes with square or rectangular cross sections were synthesized using CCVD. The cross-sectional width of the SnO2 tubules was tunable from 50 nm to sub-micrometer depending on synthesis temperature. The tubes are readily aligned in the direction perpendicular to the substrate surface to form tube arrays. Silicon wafers were electrochemically etched to produce porous silicon (PS) with honeycomb-type channels and nanoporous walls. The diameters of the channels are about 1 to 3 microns and the depth of the

  2. Synthesis and Microstructural Characterization of Manganese Oxide Electrodes for Application as Electrochemical Supercapacitors

    NASA Astrophysics Data System (ADS)

    Babakhani, Banafsheh

    The aim of this thesis work was to synthesize Mn-based oxide electrodes with high surface area structures by anodic electrodeposition for application as electrochemical capacitors. Rod-like structures provide large surface areas leading to high specific capacitances. Since templated electrosynthesis of rods is not easy to use in practical applications, it is more desirable to form rod-like structures without using any templates. In this work, Mn oxide electrodes with rod-like structures (˜1.5 µm in diameter) were synthesized from a solution of 0.01 M Mn acetate under galvanostatic control without any templates, on Au coated Si substrates. The electrochemical properties of the synthesized nanocrystalline electrodes were investigated to determine the effect of morphology, chemistry and crystal structure on the corresponding electrochemical behavior of Mn oxide electrodes. Mn oxides prepared at different current densities showed a defective antifluoritetype crystal structure. The rod-like Mn oxide electrodes synthesized at low current densities (5 mAcm.2) exhibited a high specific capacitance due to their large surface areas. Also, specific capacity retention after 250 cycles in an aqueous solution of 0.5 M Na2SO4 at 100 mVs -1 was about 78% of the initial capacity (203 Fg-1 ). To improve the electrochemical capacitive behavior of Mn oxide electrodes, a sequential approach and a one-step method were adopted to synthesize Mn oxide/PEDOT electrodes through anodic deposition on Au coated Si substrates from aqueous solutions. In the former case, free standing Mn oxide rods (about 10 µm long and less than 1.5 µm in diameter) were first synthesized, then coated by electro-polymerization of a conducting polymer (PEDOT) giving coaxial rods. The one-step, co-electrodeposition method produced agglomerated Mn oxide/PEDOT particles. The electrochemical behavior of the deposits depended on the morphology and crystal structure of the fabricated electrodes, which were affected

  3. Ink-jet printed porous composite LiFePO4 electrode from aqueous suspension for microbatteries

    NASA Astrophysics Data System (ADS)

    Delannoy, P.-E.; Riou, B.; Brousse, T.; Le Bideau, J.; Guyomard, D.; Lestriez, B.

    2015-08-01

    This work demonstrates ink-jet printed LiFePO4-based composite porous electrodes for microbattery application. As binder and dispersant, we found that aqueous inks with more suitable rheological properties with respect to ink-jet printing are prepared with the low molecular weight poly-acrylic-co-maleic acid copolymer, rather than with the carboxymethyl cellulose standard binder of the lithium-ion technology. The ink-jet printed thin and porous electrode shows very high rate charge/discharge behavior, both in LiPF6/ethylene carbonate-dimethyl carbonate (LP30) and lithium bis(trifluoromethane)sulfonylimide salt (Li-TFSI) in N-methyl-N-propylpyrrolidinium bis(trifluoromethane)suflonylimide ionic liquid (PYR13-TFSI) electrolytes, as well as good cyclability.

  4. Electrode performance parameters for a radioisotope-powered AMTEC for space power applications

    NASA Technical Reports Server (NTRS)

    Underwood, M. L.; O'Connor, D.; Williams, R. M.; Jeffries-Nakamura, B.; Ryan, M. A.; Bankston, C. P.

    1992-01-01

    The alkali metal thermoelastic converter (AMTEC) is a device for the direct conversion of heat to electricity. Recently a design of an AMTEC using a radioisotope heat source was described, but the optimum condenser temperature was hotter than the temperatures used in the laboratory to develop the electrode performance model. Now laboratory experiments have confirmed the dependence of two model parameters over a broader range of condenser and electrode temperatures for two candidate electrode compositions. One parameter, the electrochemical exchange current density at the reaction interface, is independent of the condenser temperature, and depends only upon the collision rate of sodium at the reaction zone. The second parameter, a morphological parameter, which measures the mass transport resistance through the electrode, is independent of condenser and electrode temperatures for molybdenum electrodes. For rhodium-tungsten electrodes, however, this parameter increases for decreasing electrode temperature, indicating an activated mass transport mechanism such as surface diffusion.

  5. Annealing-free, flexible silver nanowire-polymer composite electrodes via a continuous two-step spray-coating method.

    PubMed

    Choi, Dong Yun; Kang, Hyun Wook; Sung, Hyung Jin; Kim, Sang Soo

    2013-02-01

    For the realization of high-efficiency flexible optoelectronic devices, transparent electrodes should be fabricated through a low-temperature process and have the crucial feature of low surface roughness. In this paper, we demonstrated a two-step spray-coating method for producing large-scale, smooth and flexible silver nanowire (AgNW)-poly3,4-ethylenedioxythiophene:polystyrenesulfonate (PEDOT:PSS) composite electrodes. Without the high-temperature annealing process, the conductivity of the composite film was improved via the lamination of highly conductive PEDOT:PSS modified by dimethyl sulfoxide (DMSO). Under the room temperature process condition, we fabricated the AgNW-PEDOT:PSS composite film showing an 84.3% mean optical transmittance with a 10.76 Ω sq(-1) sheet resistance. The figure of merit Φ(TC) was higher than that obtained from the indium tin oxide (ITO) films. The sheet resistance of the composite film slightly increased less than 5.3% during 200 cycles of tensile and compression folding, displaying good electromechanical flexibility for use in flexible optoelectronic applications. PMID:23241687

  6. Engineering study on TiSnSb-based composite negative electrode for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Wilhelm, H. A.; Marino, C.; Darwiche, A.; Soudan, P.; Morcrette, M.; Monconduit, L.; Lestriez, B.

    2015-01-01

    Micrometric TiSnSb is a promising negative electrode material for Li-ion batteries when formulated with carboxymethyl cellulose (CMC) binder and a mixture of carbon black and carbon nanofibers, and cycled in a fluoroethylene carbonate (FEC)-containing electrolyte. Here, other binder systems were evaluated, polyacrylic acid (PAAH) mixed with CMC, CMC in buffered solution at pH 3 and amylopectin. However CMC showed the better performance in terms of cycle life of the electrode. Whatever the binder, cycle life decreases with increasing the active mass loading, which is attributed to both the precipitation of liquid electrolyte degradation products and to the loss of electrical contacts within the composite electrode and with the current collector as a consequence of the active particles volume variations. Furthermore, calendaring the electrode unfortunately decreases the cycle life. The rate performance was studied as a function of the active mass loading and was shown to be determined by the electrode polarization resistance. Finally, full cells cycling tests with Li1Ni1/3Co1/3Mn1/3O2 at the positive electrode were done. 60% of the capacity is retained after 200 cycles at the surface capacity of 2.7 mAh cm-2.

  7. Effect of Electrode Composition and Microstructure on Impedancemetric Nitric Oxide Sensors based on YSZ Electrolyte

    SciTech Connect

    Woo, L Y; Martin, L P; Glass, R S; Wang, W; Jung, S; Gorte, R J; Murray, E P; Novak, R F; Visser, J H

    2007-04-02

    The role of metal (Au, Pt, and Ag) electrodes in YSZ electrolyte-based impedancemetric nitric oxide (NO) sensors is investigated using impedance spectroscopy and equivalent circuit analysis. The test cell consists of a rectangular block of porous YSZ with two metal wire loop electrodes, both exposed to the same atmosphere. Of the electrode materials, only Au was sensitive to changes in NO concentration. The impedance behavior of porous Au electrodes in a slightly different configuration was compared with dense Au electrodes and was also insensitive to NO. Ag showed no sensitivity to either O{sub 2} or NO, and the measured impedances occurred at frequencies > 10 kHz, which are typically associated with ionic conduction in YSZ. Pt and porous Au showed sensitivity to O{sub 2}, which was quantified using power-law exponents that suggest electrochemical rate-determining mechanisms occurring at the triple phase boundary. The behavior of the dense Au suggests different rate-determining processes (e.g., diffusion or adsorption) for the O{sub 2} reaction. Although the exact mechanism is not determined, the composition and microstructure of the metal electrode seem to alter the rate-limiting step of the interfering O{sub 2} reaction. Impedance behavior of the O{sub 2} reaction that is limited by processes occurring away from the triple phase boundary may be crucial for impedancemetric NO sensing.

  8. Au nanoparticles/poly(caffeic acid) composite modified glassy carbon electrode for voltammetric determination of acetaminophen.

    PubMed

    Li, Tianbao; Xu, Juan; Zhao, Lei; Shen, Shaofei; Yuan, Maosen; Liu, Wenming; Tu, Qin; Yu, Ruijin; Wang, Jinyi

    2016-10-01

    An Au nanoparticles/poly(caffeic acid) (AuNPs/PCA) composite modified glassy carbon (GC) electrode was prepared by successively potentiostatic technique in pH 7.4 phosphate buffer solution containing 0.02mM caffeic acid and 1.0mM HAuCl4. Electrochemical characterization of the AuNPs/PCA-GC electrode was investigated by electrochemical impedance spectroscopy and cyclic voltammetry. The electrochemical behavior of acetaminophen (AP) at the AuNPs/PCA-GC electrode was also studied by cyclic voltammetry. Compared with bare GC and poly(caffeic acid) modified GC electrode, the AuNPs/PCA-GC electrode was exhibited excellent electrocatalytic activity toward the oxidation of AP. The plot of catalytic current versus AP concentration showed two linear segments in the concentration ranges 0.2-20µM and 50-1000µM. The detection limit of 14 nM was obtained by using the first range of the calibration plot. The AuNPs/PCA-GC electrode has been successfully applied and validated by analyzing AP in blood, urine and pharmaceutical samples. PMID:27474318

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

    PubMed

    Li, Jianfeng; Lee, Eun-Cheol

    2015-09-15

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

  10. Effects of Electrode Surface Morphology on the Transduction of Ionic Polymer-Metal Composites

    NASA Astrophysics Data System (ADS)

    Palmre, Viljar

    Ionic polymer-metal composites (IPMCs) are innovative smart materials that exhibit electromechanical and mechanoelectrical transduction (conversion of electrical input into mechanical deformation and vice versa). Due to low driving voltage (< 5 V) and ability to operate in aqueous environment, IPMCs are attractive for developing soft actuators and sensors for underwater robots and medical devices. This dissertation focuses on investigating the effects of electrode surface morphology in the transduction of Pt and Pd-Pt electrodes-based IPMCs, with the aim to improve the electrode surface design and thereby enhance the transduction performance of the material. Firstly, the synthesis techniques are developed to control and manipulate the surface structure of the mentioned electrodes through the electroless plating process. Using these techniques, IPMCs with different electrode surface structures are fabricated. The changes in the electrode surface morphology and the resulting effects on the material's electromechanical, mechanoelectrical, electrochemical and mechanical properties area examined and analyzed. This study shows that increasing the impregnation-reduction cycles under appropriate conditions leads to the formation and growth of platinum nanoparticles with sharp tips and edges---called Pt nanothorn assemblies---at the polymer-electrode interface. IPMCs designed with such nanostructured Pt electrodes are first to be reported. The experiments demonstrate that the formation and growth of Pt nanothorn assemblies at the electrode interface increases considerably the total transported charge during the transduction, thereby increasing significantly the displacement and blocking force output of IPMC. The improvement of the mentioned electromechanical properties was 3--5 times, depending on the input voltage and frequency used. Also, the peak mechanoelectrically induced voltage increased somewhat, although the overall effect of the surface structure was relatively

  11. Photoelectrochemical Properties of CuS-GeO2-TiO2 Composite Coating Electrode

    PubMed Central

    Wen, Xinyu; Zhang, Huawei

    2016-01-01

    The ITO (indium tin oxide) conductive glass-matrix CuS-GeO2-TiO2 composite coating was generated via EPD (electrophoretic deposition) and followed by a sintering treatment at 450°C for 40 minutes. Characterizations of the CuS-GeO2-TiO2 composite coating were taken by SEM (scanning electron microscope), XRD (X-ray diffraction), EDX (energy dispersive X-ray), UV-Vis DRS (ultraviolet-visible diffuse reflection spectrum), and FT-IR (Fourier transform infrared spectroscopy). Results showed that CuS and GeO2 had dispersed in this CuS-GeO2-TiO2 composite coating (mass percentages for CuS and GeO2 were 1.23% and 2.79%, respectively). The electrochemical studies (cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Tafel polarization) of this CuS-GeO2-TiO2 composite coating electrode were performed in pH = 9.51 Na2CO3-NaHCO3 buffer solution containing 0.50 mol/L CH3OH under the conditions of visible light, ultraviolet light (λ = 365 nm), and dark (without light irradiation as control), respectively. Electrochemical studies indicated that this CuS-GeO2-TiO2 composite coating electrode had better photoelectrocatalytic activity than the pure TiO2 electrode in the electrocatalysis of methanol under visible light. PMID:27055277

  12. Photoelectrochemical Properties of CuS-GeO2-TiO2 Composite Coating Electrode.

    PubMed

    Wen, Xinyu; Zhang, Huawei

    2016-01-01

    The ITO (indium tin oxide) conductive glass-matrix CuS-GeO2-TiO2 composite coating was generated via EPD (electrophoretic deposition) and followed by a sintering treatment at 450°C for 40 minutes. Characterizations of the CuS-GeO2-TiO2 composite coating were taken by SEM (scanning electron microscope), XRD (X-ray diffraction), EDX (energy dispersive X-ray), UV-Vis DRS (ultraviolet-visible diffuse reflection spectrum), and FT-IR (Fourier transform infrared spectroscopy). Results showed that CuS and GeO2 had dispersed in this CuS-GeO2-TiO2 composite coating (mass percentages for CuS and GeO2 were 1.23% and 2.79%, respectively). The electrochemical studies (cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Tafel polarization) of this CuS-GeO2-TiO2 composite coating electrode were performed in pH = 9.51 Na2CO3-NaHCO3 buffer solution containing 0.50 mol/L CH3OH under the conditions of visible light, ultraviolet light (λ = 365 nm), and dark (without light irradiation as control), respectively. Electrochemical studies indicated that this CuS-GeO2-TiO2 composite coating electrode had better photoelectrocatalytic activity than the pure TiO2 electrode in the electrocatalysis of methanol under visible light. PMID:27055277

  13. Chitosan composite films. Biomedical applications.

    PubMed

    Cárdenas, Galo; Anaya, Paola; von Plessing, Carlos; Rojas, Carlos; Sepúlveda, Jackeline

    2008-06-01

    Chitosan acetate films have been prepared using chitosans from shrimps (Pleuroncodes monodon) of low and high molecular weight (LMv = 68,000 g/mol and HMv = 232,000 g/mol) and deacetylation degree of 80 and 100%, respectively. The chitosan films were obtained by addition of several additives to acetic acid chitosan solutions, such as: glycerol, oleic acid and linoleic acid in different proportions. The pH of the solutions before casting ranged from 5.0 to 6.0. The composite film thickness are reported. The films have been analyzed by FTIR showing characteristic bands corresponding to the additives. The scanning electron microscopy (SEM) studies reveals the different morphology of the composite films. The films exhibit different physical properties depending upon the additives and/or mixture of them. The addition of glycerol to composite improves the elasticity of the films. The swelling in glucose and saline solutions for several films was evaluated, being higher in the glucose solution. The bactericide test against Staphylococcus aureus, Pseudomona aeruginosa and Acinetobacter baumanii in plates with either blood and or agar tripticase showed that the molecular weight influences on the bactericidal properties of the chitosan composite films and over its effect against gram positive and gram negative bacteria. Medical applications of the composite films were done in patients with burns, ulcers and injuries, the films containing glycerol showed good adhesion in comparison with those without it. The composite films tested were mainly three (1) chitosan acetate with glycerol, (2) chitosan acetate with oleic acid and (3) chitosan acetate with glycerol and oleic acid. Excellent results in the skin recovery were obtained after 7-10 days. Since the chitosan is biodegradable by the body enzymes it does not need to be removed and increases the gradual grows of the damage tissues. PMID:18165888

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

    NASA Astrophysics Data System (ADS)

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

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

  15. Overview on macrofiber composite applications

    NASA Astrophysics Data System (ADS)

    Schönecker, Andreas J.; Daue, Thomas; Brückner, Bent; Freytag, Christian; Hähne, Ludwig; Rödig, Thomas

    2006-03-01

    Developed at NASA Langley Research Center during the late 90's, the Macro Fiber Composites (MFC) are manufactured by Smart Material Corp. in a full-scale production, today. Numerous research projects have proven the concept of using the MFC in vibration and noise control applications, as well as for health monitoring, morphing of structures and energy harvesting. Because basic performance parameters of products are considerably improved, like for example energy economy, precision and comfort, a widespread use of active structures is expected in the next future. Different MFC types are commercially available meeting already the requirements of a variety of applications. The migration from research projects to high volume, cost effective commercial applications has generated additional need for new MFC designs, electronics on microcontroller and chip level, and system design tools, as well. In this paper, we give an overview of recent progress in the development of the MFC transducers and MFC systems technology.

  16. Ceramic composites for biomedical applications.

    PubMed

    Rieu, J; Goeuriot, P

    1993-01-01

    Ceramics have been successfully used for more than twenty years for orthopaedic prostheses, as articulating bearing surfaces against ceramic or polymer components. In both cases, ceramics are characterized by low friction coefficient and low wear rate, compared to metallic materials (stainless steels, titanium and chromium-cobalt alloys). However, their brittleness is much higher than that of metals and presently restricts the use of ceramics for hip joint balls or knee condyles. In the material science field, it is very well known that the association of two different materials can lead to new materials, often called 'composites'. Their properties can be higher than the same properties of each of the individual materials, when taken separately. Nevertheless, the word 'composites' is not universally used with the same meaning. For this reason, we will first give a few definitions in order to clearly understand what can be called 'composite' for ceramic materials. Dispersed phases increase the fracture toughness and high temperature mechanical behaviour of ceramics. In this paper, devoted to medical applications, only mechanical properties at the low (body or room) temperature are analysed. Particular attention is given to the alumina-zirconia system, because aluminium and zirconium oxides are currently accepted as biomaterials for joint prostheses. Finally, a highlight is given on the difficulties in the technological processes to obtain improved ceramic composites. PMID:10171689

  17. 2D Cross Sectional Analysis and Associated Electrochemistry of Composite Electrodes Containing Dispersed Agglomerates of Nanocrystalline Magnetite, Fe₃O₄.

    PubMed

    Bock, David C; Kirshenbaum, Kevin C; Wang, Jiajun; Zhang, Wei; Wang, Feng; Wang, Jun; Marschilok, Amy C; Takeuchi, Kenneth J; Takeuchi, Esther S

    2015-06-24

    When electroactive nanomaterials are fully incorporated into an electrode structure, characterization of the crystallite sizes, agglomerate sizes, and dispersion of the electroactive materials can lend insight into the complex electrochemistry associated with composite electrodes. In this study, composite magnetite electrodes were sectioned using ultramicrotome techniques, which facilitated the direct observation of crystallites and agglomerates of magnetite (Fe3O4) as well as their dispersal patterns in large representative sections of electrode, via 2D cross sectional analysis by Transmission Electron Microscopy (TEM). Further, the electrochemistry of these electrodes were recorded, and Transmission X-ray Microscopy (TXM) was used to determine the distribution of oxidation states of the reduced magnetite. Unexpectedly, while two crystallite sizes of magnetite were employed in the production of the composite electrodes, the magnetite agglomerate sizes and degrees of dispersion in the two composite electrodes were similar to each other. This observation illustrates the necessity for careful characterization of composite electrodes, in order to understand the effects of crystallite size, agglomerate size, and level of dispersion on electrochemistry. PMID:26024206

  18. Three dimensional studies of particle failure in silicon based composite electrodes for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Gonzalez, Joseph; Sun, Ke; Huang, Meng; Lambros, John; Dillon, Shen; Chasiotis, Ioannis

    2014-12-01

    Silicon based composite electrodes for lithium ion batteries are of significant interest because of their potential to be high capacity alternatives to the commonly used graphitic carbon anodes. A drawback to their use, however, is the Si particle debonding and fracture that occurs as a result of the volumetric expansion by the lithium host particles upon lithiation of the anode electrode. We use X-ray micro computed tomography to visualize the evolution of the internal microstructure of a silicon-based electrode before and after four lithiation steps during the first half cycle of the cell. We develop a novel threshold edge detect method to perform 3D volumetric measurements of silicon particle expansion. According to our results, 100% lithiation of the composite anode resulted in up to 290% volume expansion of individual Si particles. Furthermore, the global and localized image intensity histogram profiles from 3D data were used to analyze the silicon particle X-ray attenuation effects as a function of lithiation: a decreasing attenuation with lithiation and the propagation of the reaction front through a core-shell process between the original state and 25% lithiation of the silicon-based electrode have been observed.

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

    PubMed Central

    Liu, Yang; Zhou, Junbo

    2014-01-01

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

  20. Large-scale graphene-based composite films for flexible transparent electrodes fabricated by electrospray deposition

    NASA Astrophysics Data System (ADS)

    Kim, Woo Sik; Moon, Sook Young; Kim, Hui Jin; Park, Sungjin; Koyanagi, Jun; Huh, Hoon

    2014-12-01

    Large-scale transparent conducting electrodes were fabricated using the electrospray method on a glass wafer and polyethylene terephthalate film using chemically reduced graphene oxide and poly (3,4-ethylenedioxythiophene) (PEDOT). Graphene oxide (GO) is prepared by the modified Hummers method, and reduced GO (RG) is prepared at low temperature. By varying the concentration of RG and PEDOT of the composite material on the substrate, the electrical conductivity and transmittance of the electrode was controlled. The optical transmittance values of the graphene-based electrode at a wavelength of 550 nm were between 81 and 95% and had sheet resistances from 370 to 5400 Ω sq-1. After 1000 cycles of a bending test, the sheet resistances of the graphene-based composite films were unchanged. Different types of graphene and graphene-based electrodes were characterized by field-emission scanning electron microscopy, high-resolution transmission electron microscopy, high-resolution Raman spectroscopy, x-ray photoelectron spectroscopy, x-ray diffraction, transmittance, and electrical conductivity measurements.

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

    PubMed

    Liu, Yang; Zhou, Junbo

    2014-01-01

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

  2. Mesoporous metal oxide microsphere electrode compositions and their methods of making

    DOEpatents

    Parans Paranthaman, Mariappan; Bi, Zhonghe; Bridges, Craig A; Brown, Gilbert M

    2014-12-16

    Compositions and methods of making are provided for treated mesoporous metal oxide microspheres electrodes. The compositions comprise (a) microspheres with an average diameter between 200 nanometers (nm) and 10 micrometers (.mu.m); (b) mesopores on the surface and interior of the microspheres, wherein the mesopores have an average diameter between 1 nm and 50 nm and the microspheres have a surface area between 50 m.sup.2/g and 500 m.sup.2/g, and wherein the composition has an electrical conductivity of at least 1.times.10.sup.-7 S/cm at 25.degree. C. and 60 MPa. The methods of making comprise forming a mesoporous metal oxide microsphere composition and treating the mesoporous metal oxide microspheres by at least one method selected from the group consisting of: (i) annealing in a reducing atmosphere, (ii) doping with an aliovalent element, and (iii) coating with a coating composition.

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

    PubMed

    Zhang, Luyan; Zhang, Wei; Chen, Gang

    2015-11-10

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

  4. Electrosorption of ions from aqueous solutions with carbon nanotubes and nanofibers composite film electrodes

    SciTech Connect

    Wang, X. Z.; Li, M. G.; Chen, Y. W.; Cheng, R. M.; Huang, S. M.; Pan, L. K.; Sun, Z.

    2006-07-31

    Electrosorption of ions from aqueous solutions with carbon nanotubes and nanofibers (CNTs-CNFs) composite film electrodes has been demonstrated. The large area CNTs-CNFs film was directly grown on Ni plate by low pressure and low temperature thermal chemical vapor deposition. The CNTs-CNFs electrodes have great advantages such as low cost, easy operation, long-term reproducibility, and integrity of monolithic CNTs-CNFs film and current collector. Batch-mode experiments at low voltage (0.4-2 V) were conducted in a continuously recycling system to investigate the electrosorption process. Purification of water with good reproducibility was achieved because of optimal pore size distribution of CNTs-CNFs composite films.

  5. Electrosorption of ions from aqueous solutions with carbon nanotubes and nanofibers composite film electrodes

    NASA Astrophysics Data System (ADS)

    Wang, X. Z.; Li, M. G.; Chen, Y. W.; Cheng, R. M.; Huang, S. M.; Pan, L. K.; Sun, Z.

    2006-07-01

    Electrosorption of ions from aqueous solutions with carbon nanotubes and nanofibers (CNTs-CNFs) composite film electrodes has been demonstrated. The large area CNTs-CNFs film was directly grown on Ni plate by low pressure and low temperature thermal chemical vapor deposition. The CNTs-CNFs electrodes have great advantages such as low cost, easy operation, long-term reproducibility, and integrity of monolithic CNTs-CNFs film and current collector. Batch-mode experiments at low voltage (0.4-2V) were conducted in a continuously recycling system to investigate the electrosorption process. Purification of water with good reproducibility was achieved because of optimal pore size distribution of CNTs-CNFs composite films.

  6. Low energy milling method, low crystallinity alloy, and negative electrode composition

    DOEpatents

    Le, Dihn B; Obrovac, Mark N; Kube, Robert Y; Landucci, James R

    2012-10-16

    A method of making nanostructured alloy particles includes milling a millbase in a pebble mill containing milling media. The millbase comprises: (i) silicon, and (ii) at least one of carbon or a transition metal, and wherein the nanostructured alloy particles are substantially free of crystalline domains greater than 50 nanometers in size. A method of making a negative electrode composition for a lithium ion battery including the nanostructured alloy particles is also disclosed.

  7. Pt-Free Counter Electrodes with Carbon Black and 3D Network Epoxy Polymer Composites

    PubMed Central

    Kang, Gyeongho; Choi, Jongmin; Park, Taiho

    2016-01-01

    Carbon black (CB) and a 3D network epoxy polymer composite, representing dual functions for conductive corrosion protective layer (CCPL) and catalytic layer (CL) by the control of CB weight ratio against polymer is developed. Our strategy provides a proper approach which applies high catalytic ability and chemical stability of CB in corrosive triiodide/iodide (I3−/I−) redox electrolyte system. The CB and a 3D network epoxy polymer composite coated on the stainless steel (SS) electrode to alternate counter electrodes in dye sensitized solar cells (DSSCs). A two-step spray pyrolysis process is used to apply a solution containing epoxy monomers and a polyfunctional amine hardener with 6 wt% CB to a SS substrate, which forms a CCPL. Subsequently, an 86 wt% CB is applied to form a CL. The excellent catalytic properties and corrosion protective properties of the CB and 3D network epoxy polymer composites produce efficient counter electrodes that can replace fluorine-doped tin oxide (FTO) with CCPL/SS and Pt/FTO with CL/CCPL/SS in DSSCs. This approach provides a promising approach to the development of efficient, stable, and cheap solar cells, paving the way for large-scale commercialization. PMID:26961256

  8. Pt-Free Counter Electrodes with Carbon Black and 3D Network Epoxy Polymer Composites

    NASA Astrophysics Data System (ADS)

    Kang, Gyeongho; Choi, Jongmin; Park, Taiho

    2016-03-01

    Carbon black (CB) and a 3D network epoxy polymer composite, representing dual functions for conductive corrosion protective layer (CCPL) and catalytic layer (CL) by the control of CB weight ratio against polymer is developed. Our strategy provides a proper approach which applies high catalytic ability and chemical stability of CB in corrosive triiodide/iodide (I3‑/I‑) redox electrolyte system. The CB and a 3D network epoxy polymer composite coated on the stainless steel (SS) electrode to alternate counter electrodes in dye sensitized solar cells (DSSCs). A two-step spray pyrolysis process is used to apply a solution containing epoxy monomers and a polyfunctional amine hardener with 6 wt% CB to a SS substrate, which forms a CCPL. Subsequently, an 86 wt% CB is applied to form a CL. The excellent catalytic properties and corrosion protective properties of the CB and 3D network epoxy polymer composites produce efficient counter electrodes that can replace fluorine-doped tin oxide (FTO) with CCPL/SS and Pt/FTO with CL/CCPL/SS in DSSCs. This approach provides a promising approach to the development of efficient, stable, and cheap solar cells, paving the way for large-scale commercialization.

  9. Pt-Free Counter Electrodes with Carbon Black and 3D Network Epoxy Polymer Composites.

    PubMed

    Kang, Gyeongho; Choi, Jongmin; Park, Taiho

    2016-01-01

    Carbon black (CB) and a 3D network epoxy polymer composite, representing dual functions for conductive corrosion protective layer (CCPL) and catalytic layer (CL) by the control of CB weight ratio against polymer is developed. Our strategy provides a proper approach which applies high catalytic ability and chemical stability of CB in corrosive triiodide/iodide (I3(-)/I(-)) redox electrolyte system. The CB and a 3D network epoxy polymer composite coated on the stainless steel (SS) electrode to alternate counter electrodes in dye sensitized solar cells (DSSCs). A two-step spray pyrolysis process is used to apply a solution containing epoxy monomers and a polyfunctional amine hardener with 6 wt% CB to a SS substrate, which forms a CCPL. Subsequently, an 86 wt% CB is applied to form a CL. The excellent catalytic properties and corrosion protective properties of the CB and 3D network epoxy polymer composites produce efficient counter electrodes that can replace fluorine-doped tin oxide (FTO) with CCPL/SS and Pt/FTO with CL/CCPL/SS in DSSCs. This approach provides a promising approach to the development of efficient, stable, and cheap solar cells, paving the way for large-scale commercialization. PMID:26961256

  10. Coulometric differential FFT admittance voltammetry determination of Amlodipine in pharmaceutical formulation by nano-composite electrode.

    PubMed

    Norouzi, Parviz; Gupta, Vinod Kumar; Larijani, Bagher; Rasoolipour, Solmaz; Faridbod, Farnoush; Ganjali, Mohammad R

    2015-01-01

    An electrochemical detection technique based on combination of was coulometric differential fast Fourier transformation admittance voltammetry (CDFFTAV) and nano-composite film modified glassy carbon electrode was successfully applied for sensitive determination of Amlodipine. The nano-composite film was made by a mixture of ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4), multiwall carbon nanotube and Au nanoparticles as electrochemical mediators. Studies reveal that the irreversible oxidation of Amlodipine was highly facile on the electrode surface. The electrochemical response was established on calculation of the charge under the admittance peak, which was obtained by discrete integration of the admittance response in a selected potential range, obtained in a flow injection analysis. Once established the best operative optimum conditions, the resulting nano-composite film electrode showed a catalytic effect on the oxidation of the analyte. The response is linear in the Amlodipine concentration range of 1.0 × 10(-9) to 2.0 × 10(-7)M with a detection limit of 1.25 × 10(-10)M. Moreover, the proposed technique exhibited high sensitivity, fast response time (less than 6s) and long-term stability and reproducibility around 96%, and it was successfully used to the determination of Amlodipine content in the pharmaceutical formulation. PMID:25281143

  11. Three-dimensional graphene-based composites for energy applications

    NASA Astrophysics Data System (ADS)

    Mao, Shun; Lu, Ganhua; Chen, Junhong

    2015-04-01

    Three-dimensional (3D) graphene-based composites have drawn increasing attention for energy applications due to their unique structures and properties. By combining the merits of 3D graphene (3DG), e.g., a porous and interconnected network, a high electrical conductivity, a large accessible surface area, and excellent mechanical strength and thermal stability, with the high chemical/electrochemical activities of active materials, 3DG-based composites show great promise as high-performance electrode materials in various energy devices. This article reviews recent progress in 3DG-based composites and their applications in energy storage/conversion devices, i.e., supercapacitors, lithium-ion batteries, dye-sensitized solar cells, and fuel cells.

  12. Three-dimensional microporous polypyrrole/polysulfone composite film electrode for supercapacitance performance

    NASA Astrophysics Data System (ADS)

    Feng, Xiaojuan; Shi, Yanlong; Jin, Shuping

    2015-10-01

    The three-dimensional microporous polypyrrole/polysulfone (PPY/PSF) composite film was fabricated via a simple polymerization method. The morphology structure and chemical composition of the composite film were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), respectively. The electrochemical properties of the composite film electrode were evaluated by cyclic voltammetry, galvanostatic charging-discharging and electrochemical impedance spectroscopy. The material exhibits excellent capacitance performance including high capacitance of 500 F g-1 at 0.3 A g-1 current density, good cycle stability in 800 continuous cycles (only 4.5% decay after 800 cycles at 0.3 A g-1), and low inter resistance. The good property of the PPY/PSF electrode should be attributed to its structural features, including two-layer microporous structure which facilitates the penetration of electrolytes into the inner surface, high surface area which provides more active sites. These results show that the composite film is a promising candidate for high energy electrochemical capacitors.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  14. Composites applications - The future is now

    SciTech Connect

    Drozda, T.J.

    1989-01-01

    The present volume on the development status of advanced composites discusses resin-, ceramic- and metal-matrix composites, as well as tooling practices, testing and inspection methods, and novel applications. Attention is given to interface considerations in ceramic-matrix composites, applications of metal-matrix composites to military aircraft, advanced thermoplastic preforms, tooling for filament-winding processes, trapped-rubber molding methods, pultrusion for automotive applications, and composite-production tooling using CAD/CAM. Also discussed are expert systems for composites inspection and repair, acoustographic high-speed NDE for composites, the design and production of a composite landing gear-retracting beam, braided composite structures, and the uses of composites in orthopedics.

  15. Biocompatible PEDOT:Nafion composite electrode coatings for selective detection of neurotransmitters in vivo.

    PubMed

    Vreeland, Richard F; Atcherley, Christopher W; Russell, Wilfred S; Xie, Jennifer Y; Lu, Dong; Laude, Nicholas D; Porreca, Frank; Heien, Michael L

    2015-03-01

    A Nafion and poly(3,4-ethylenedioxythiophene) (PEDOT) containing composite polymer has been electropolymerized on carbon-fiber microelectrodes with the goal of creating a mechanically stable, robust, and controllable electrode coating that increases the selectivity and sensitivity of in vivo electrochemical measurements. The coating is deposited on carbon-fiber microelectrodes by applying a triangle waveform from +1.5 V to -0.8 V and back in a dilute solution of ethylenedioxythiophene (EDOT) and Nafion in acetonitrile. Scanning electron microscopy demonstrated that the coating is uniform and ∼100 nm thick. Energy-dispersive X-ray spectroscopy demonstrated that both sulfur and fluorine are present in the coating, indicating the incorporation of PEDOT (poly(3,4-ethylenedioxythiophene) and Nafion. Two types of PEDOT:Nafion coated electrodes were then analyzed electrochemically. PEDOT:Nafion-coated electrodes made using 200 μM EDOT exhibit a 10-90 response time of 0.46 ± 0.09 s versus 0.45 ± 0.11 s for an uncoated fiber in response to a 1.0 μM bolus of dopamine. The electrodes coated using a higher EDOT concentration (400 μM) are slower with a 10-90 response time of 0.84 ± 0.19 s, but display increased sensitivity to dopamine, at 46 ± 13 nA/μM, compared to 26 ± 6 nA/μM for the electrodes coated in 200 μM EDOT and 13 ± 2 nA/μM for an uncoated fiber. PEDOT:Nafion-coated electrodes were lowered into the nucleus accumbens of a rat, and both spontaneous and electrically evoked dopamine release were measured. In addition to improvements in sensitivity and selectivity, the coating dramatically reduces acute in vivo biofouling. PMID:25692657

  16. Carbon Nanotubes Reinforced Composites for Biomedical Applications

    PubMed Central

    Wang, Wei; Zhu, Yuhe; Liao, Susan; Li, Jiajia

    2014-01-01

    This review paper reported carbon nanotubes reinforced composites for biomedical applications. Several studies have found enhancement in the mechanical properties of CNTs-based reinforced composites by the addition of CNTs. CNTs reinforced composites have been intensively investigated for many aspects of life, especially being made for biomedical applications. The review introduced fabrication of CNTs reinforced composites (CNTs reinforced metal matrix composites, CNTs reinforced polymer matrix composites, and CNTs reinforced ceramic matrix composites), their mechanical properties, cell experiments in vitro, and biocompatibility tests in vivo. PMID:24707488

  17. Preparation and analytical application of the novel Hg(II)-selective membrane electrodes based on oxime compounds.

    PubMed

    Sardohan-Koseoglu, Tugba; Kir, Esengul; Dede, Bulent

    2015-04-15

    Novel Hg(II)-selective poly(vinyl) chloride (PVC) membrane electrodes based on oxime compounds of (4-(4-methylphenylaminoisonitrosoacetyl)biphenyl, I1; 4-(4-clorophenylaminoisonitrosoacetyl)biphenyl, I2; N,N-bis[1-(4-phenylphenyl)-2-hydroxyimino-2-(4-chloroaniline)-1-ethylidene]-diethylenetriamine, I3 and N,N-bis[1-(4-phenylphenyl)-2-hydroxyimino-2-(4-chloroaniline)-1-ethylidene]- 1,3-propanediamine), I4 were developed. Effects of the species and ratios of ionophore, plasticizer, PVC and lipophilic additive on the potentiometric response of electrodes were investigated in order to determine the electrode specifications. Overall results revealed that the optimum membrane composition was: 4% ionophore, 64% plasticizer (o-NPOE), 31% PVC, and 1% lipophilic additive (NaTPB). Obtained results showed that the electrodes have detection limit of 1.76×10(-6), 1.68×10(-6), 2.35×10(-6) and 2.44×10(-6) and have linear responses of 34.2, 33.4, 35.9 and 37.6 mV/pHg(2+) for a wide concentration range of Hg(II) ions. According to durability studies, the electrodes can be used for approximately 1 month without any considerable divergence in potential values. Analytical applications of the electrodes were performed and it was found that developed electrodes can successfully be used as indicator electrodes for the potentiometric titration of Hg(II) ion with EDTA solution. PMID:25585282

  18. Atomic and Molecular Layer Deposition for Enhanced Lithium Ion Battery Electrodes and Development of Conductive Metal Oxide/Carbon Composites

    NASA Astrophysics Data System (ADS)

    Travis, Jonathan

    The performance and safety of lithium-ion batteries (LIBs) are dependent on interfacial processes at the positive and negative electrodes. For example, the surface layers that form on cathodes and anodes are known to affect the kinetics and capacity of LIBs. Interfacial reactions between the electrolyte and the electrodes are also known to initiate electrolyte combustion during thermal runaway events that compromise battery safety. Atomic layer deposition (ALD) and molecular layer deposition (MLD) are thin film deposition techniques based on sequential, self-limiting surface reactions. ALD and MLD can deposit ultrathin and conformal films on high aspect ratio and porous substrates such as composite particulate electrodes in lithium-ion batteries. The effects of electrode surface modification via ALD and MLD are studied using a variety of techniques. It was found that sub-nm thick coatings of Al2O 3 deposited via ALD have beneficial effects on the stability of LIB anodes and cathodes. These same Al2O3 ALD films were found to improve the safety of graphite based anodes through prevention of exothermic solid electrolyte interface (SEI) degradation at elevated temperatures. Ultrathin and conformal metal alkoxide polymer films known as "metalcones" were grown utilizing MLD techniques with trimethylaluminum (TMA) or titanium tetrachloride (TiCl4) and organic diols or triols, such as ethylene glycol (EG), glycerol (GL) or hydroquinone (HQ), as the reactants. Pyrolysis of these metalcone films under inert gas conditions led to the development of conductive metal oxide/carbon composites. The composites were found to contain sp2 carbon using micro-Raman spectroscopy in the pyrolyzed films with pyrolysis temperatures ≥ 600°C. Four point probe measurements demonstrated that the graphitic sp2 carbon domains in the metalcone films grown using GL and HQ led to significant conductivity. The pyrolysis of conformal MLD films to obtain conductive metal oxide/carbon composite films

  19. Silicon oxycarbide glass-graphene composite paper electrode for long-cycle lithium-ion batteries

    PubMed Central

    David, Lamuel; Bhandavat, Romil; Barrera, Uriel; Singh, Gurpreet

    2016-01-01

    Silicon and graphene are promising anode materials for lithium-ion batteries because of their high theoretical capacity; however, low volumetric energy density, poor efficiency and instability in high loading electrodes limit their practical application. Here we report a large area (approximately 15 cm × 2.5 cm) self-standing anode material consisting of molecular precursor-derived silicon oxycarbide glass particles embedded in a chemically-modified reduced graphene oxide matrix. The porous reduced graphene oxide matrix serves as an effective electron conductor and current collector with a stable mechanical structure, and the amorphous silicon oxycarbide particles cycle lithium-ions with high Coulombic efficiency. The paper electrode (mass loading of 2 mg cm−2) delivers a charge capacity of ∼588 mAh g−1electrode (∼393 mAh cm−3electrode) at 1,020th cycle and shows no evidence of mechanical failure. Elimination of inactive ingredients such as metal current collector and polymeric binder reduces the total electrode weight and may provide the means to produce efficient lightweight batteries. PMID:27025781

  20. Silicon oxycarbide glass-graphene composite paper electrode for long-cycle lithium-ion batteries.

    PubMed

    David, Lamuel; Bhandavat, Romil; Barrera, Uriel; Singh, Gurpreet

    2016-01-01

    Silicon and graphene are promising anode materials for lithium-ion batteries because of their high theoretical capacity; however, low volumetric energy density, poor efficiency and instability in high loading electrodes limit their practical application. Here we report a large area (approximately 15 cm × 2.5 cm) self-standing anode material consisting of molecular precursor-derived silicon oxycarbide glass particles embedded in a chemically-modified reduced graphene oxide matrix. The porous reduced graphene oxide matrix serves as an effective electron conductor and current collector with a stable mechanical structure, and the amorphous silicon oxycarbide particles cycle lithium-ions with high Coulombic efficiency. The paper electrode (mass loading of 2 mg cm(-2)) delivers a charge capacity of ∼588 mAh g(-1)electrode (∼393 mAh cm(-3)electrode) at 1,020th cycle and shows no evidence of mechanical failure. Elimination of inactive ingredients such as metal current collector and polymeric binder reduces the total electrode weight and may provide the means to produce efficient lightweight batteries. PMID:27025781

  1. Silicon oxycarbide glass-graphene composite paper electrode for long-cycle lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    David, Lamuel; Bhandavat, Romil; Barrera, Uriel; Singh, Gurpreet

    2016-03-01

    Silicon and graphene are promising anode materials for lithium-ion batteries because of their high theoretical capacity; however, low volumetric energy density, poor efficiency and instability in high loading electrodes limit their practical application. Here we report a large area (approximately 15 cm × 2.5 cm) self-standing anode material consisting of molecular precursor-derived silicon oxycarbide glass particles embedded in a chemically-modified reduced graphene oxide matrix. The porous reduced graphene oxide matrix serves as an effective electron conductor and current collector with a stable mechanical structure, and the amorphous silicon oxycarbide particles cycle lithium-ions with high Coulombic efficiency. The paper electrode (mass loading of 2 mg cm-2) delivers a charge capacity of ~588 mAh g-1electrode (~393 mAh cm-3electrode) at 1,020th cycle and shows no evidence of mechanical failure. Elimination of inactive ingredients such as metal current collector and polymeric binder reduces the total electrode weight and may provide the means to produce efficient lightweight batteries.

  2. Determination of two metals from a single potentiometric titration curve The application of two indicator electrodes.

    PubMed

    Parczewski, A

    1988-06-01

    The advantages of applying two indicator electrodes in complexometric potentiometric multicomponent titration are shown by means of simulated titration curves. Two measurement arrangements have been considered, one in which the indicator electrodes are directly connected to a voltmeter and the other in which the electrodes are connected to the voltmeter through a summing operational amplifier. They have been compared with the conventional arrangement of a single indicator electrode and a reference electrode. The influence of the stability constants of the complexes in solution and of the electrode parameters on the shape of titration curves has been examined. It is shown that the use of two indicator electrodes may significantly increase the applicability of multicomponent potentiometric titrations. PMID:18964554

  3. Templated synthesis, characterization, and sensing application of macroscopic platinum nanowire network electrodes.

    PubMed

    Wang, Donghai; Kou, Rong; Gil, Maria P; Jakobson, Hans Peter; Tang, Jing; Yu, Donghong; Lu, Yunfeng

    2005-11-01

    Novel platinum nanowire network electrodes have been fabricated through electrodeposition using mesoporous silica thin films as templates. These electrodes were characterized by X-ray diffraction, transmission electron microscope, and scanning electron microscope. The electrochemical properties of the electrodes, such as electrochemical active area and methanol oxidation, have also been studied. Compared with conventional polycrystalline Pt electrodes, these novel nanowire network electrodes possess high electrochemical active areas and demonstrate higher current densities and a lower onset potential for methanol electro-oxidation. Enzymatic Pt nanowire-network-based sensors show higher sensitivity for glucose detection than that using conventional polycrystalline Pt electrode. Such macroscopic nanowire network electrodes provide ideal platforms for sensing and other device applications. PMID:16433429

  4. Thermal Stability of Co-Sputtered Ru Ti Alloy Electrodes for Dynamic Random Access Memory Applications

    NASA Astrophysics Data System (ADS)

    Horng, Ray-Hua; Wuu, Dong-Sing; Wu, Luh-Huei; Lee, Ming-Kwei; Chan, Shih-Hsiung; Leu, Ching-Chich; Huang, Tiao-Yuan; Sze, Simon

    1998-10-01

    Ru Ti alloy films were studied for use as a bottom electrode of ferroelectric/paraelectric thin film capacitors. These thin films with different Ru/Ti compositions were first prepared by co-sputtering. The Ru/Ti ratio in the alloy was found to strongly affect the resistivity, structure formation and thermal stability. The resistivity of the as-deposited films decreases and closes to that of pure Ru metal films as the amount of Ru atoms increasing. From X-ray diffraction measurement, it was found that the RuTi phase has formed for the as-deposited sample. There also exist Ru and Ti phases for Ru-enriched and Ti-enriched samples, respectively. As-deposited alloy films were also annealed by rapid thermal processing (RTP, 600 750°C, 1 min) in oxygen ambient to simulate the processing of ferroelectric/paraelectric thin film capacitors. It was found that the composition of the thin film has a large effect on the thermal stability. The resistivity of alloy thin films is thermally stable as the Ru composition varies from 0.68 to 0.81. It may be due to the RuTiO2 formation at the surface and play an important role in preventing further oxidation of the Ru-enriched layer. This oxide also presents conductive behavior. On the other hand, the interface between Ru-enriched alloys and Si substrate was still sharp for the RTP-treated sample at 600°C for 1 min. The alloy film with high Ru composition shows excellent thermal stability and barriers against interdiffusion of Si and oxygen. These results suggest that the Ru-enriched alloy films are suitable for the bottom electrode application in ferroelectric/paraelectric thin film capacitors.

  5. Working from Both Sides: Composite Metallic Semitransparent Top Electrode for High Performance Perovskite Solar Cells.

    PubMed

    Dai, Xuezeng; Zhang, Ye; Shen, Heping; Luo, Qiang; Zhao, Xingyue; Li, Jianbao; Lin, Hong

    2016-02-01

    We report herein perovskite solar cells using solution-processed silver nanowires (AgNWs) as transparent top electrode with markedly enhanced device performance, as well as stability by evaporating an ultrathin transparent Au (UTA) layer beneath the spin-coated AgNWs forming a composite transparent metallic electrode. The interlayer serves as a physical separation sandwiched in between the perovskite/hole transporting material (HTM) active layer and the halide-reactive AgNWs top-electrode to prevent undesired electrode degradation and simultaneously functions to significantly promote ohmic contact. The as-fabricated semitransparent PSCs feature a Voc of 0.96 V, a Jsc of 20.47 mA cm(-2), with an overall PCE of over 11% when measured with front illumination and a Voc of 0.92 V, a Jsc of 14.29 mA cm(-2), and an overall PCE of 7.53% with back illumination, corresponding to approximately 70% of the value under normal illumination conditions. The devices also demonstrate exceptional fabrication repeatability and air stability. PMID:26820688

  6. Poly(3,4-ethylenedioxithiophene)/MnO 2 composite electrodes for electrochemical capacitors

    NASA Astrophysics Data System (ADS)

    Rios, Emerson C.; Correa, Alessandra A.; Cristovan, Fernando H.; Pocrifka, Leandro A.; Rosario, Adriane V.

    2011-11-01

    Composite electrodes of poly(3,4-ethylenedioxithiophene) and manganese oxide (PEDOT/MnO 2) have been prepared by electrodeposition of manganese oxide over PEDOT-modified titanium substrate. The PEDOT layers are deposited on titanium by potentiostatic deposition at 1.4 V and at two different temperatures: 5 and 25 °C (named PEDOT (5) and PEDOT (25), respectively). The electrodes are characterized by field emission gun scanning electron microscopy (FEG-SEM) and their electrochemical performances are evaluated by using cyclic voltammetry (CV) in 1 molL -1 Na 2SO 4. The results show an improvement in the specific capacitance ( C s) of the oxide due to the presence of the polymer layer. Considering only the MnO 2 mass, the C s values of the electrodes Ti/MnO 2, Ti/PEDOT (5)/MnO 2 and Ti/PEDOT (25)/MnO 2, estimated by the CV technique, are 151, 159 and 199 Fg -1 at 10 mVs -1 respectively. The micrographies of electrodes show that the polymer layer leads to very significant changes in the morphology of the oxide layers, which in turn generates the improvement observed in the capacitive property.

  7. Electrochemical preparation of sodium dodecylsulfate doped over-oxidized polypyrrole/multi-walled carbon nanotube composite on glassy carbon electrode and its application on sensitive and selective determination of anticancer drug: pemetrexed.

    PubMed

    Karadas, Nurgul; Ozkan, Sibel A

    2014-02-01

    Electrochemical oxidation of pemetrexed (PMX) was studied on bare, carboxylic acid functionalized multi-walled carbon nanotubes and over-oxidized polypyrrole modified (oo-PPy/MWCNTs-COOH/GCE) glassy carbon electrodes by cyclic and adsorptive stripping differential pulse voltammetric techniques. The oo-PPy/MWCNTs-COOH/GCE is very sensitive to the oxidation of PMX. The results proved that the over-oxidation of the PPy film gave a negative charge density on porous layer that improved the adsorption for PMX. The effects of pH, concentrations of MWCNTs and monomer, the number of cycles for the electropolymerization and the scan rate for sensor preparation were optimized. The MWCNTs-COOH and oo-PPy based sensor showed an excellent recognition capacity toward PMX. The linear responses have been obtained in the range from 8.00 × 10(-7)M to 1.00 × 10(-4)M with 2.04 × 10(-7)M detection limit for the bare GCE and from 1.00 × 10(-8)M to 1.00 × 10(-7)M with 3.28 × 10(-9)M detection limit for the modified GCE. The oxidation of PMX was controlled by the adsorption process on both types of electrode surfaces. The proposed methods were compared with the literature on UV spectrophotometric assay, which was carried out at an absorption maximum of 225 nm. The proposed method and the designed sensors have been successfully applied for the determination of PMX in pharmaceuticals. PMID:24401411

  8. Grid indentation analysis of mechanical properties of composite electrodes in Li-ion batteries

    DOE PAGESBeta

    Vasconcelos, Luize Scalco de; Xu, Rong; Li, Jianlin; Zhao, Kejie

    2016-03-09

    We report that electrodes in commercial rechargeable batteries are microscopically heterogeneous materials. The constituent components, including active materials, polymeric binders, and porous conductive matrix, often have large variation in their mechanical properties, making the mechanical characterization of composite electrodes a challenging task. In a model system of LiNi0.5Mn0.3Co0.2O2 cathode, we employ the instrumented grid indentation to determine the elastic modulus and hardness of the constituent phases. The approach relies on a large array of nanoindentation experiments and statistical analysis of the resulting data provided that the maximum indentation depth is carefully chosen. The statistically extracted properties of the active particlesmore » and the surrounding medium are in good agreement with the tests of targeted indentation at selected sites. Lastly, the combinatory technique of grid indentation and statistical deconvolution represents a fast and reliable route to quantify the mechanical properties of composite electrodes that feed the parametric input for the mechanics models.« less

  9. Carbon/lambda-MnO{sub 2} composites for supercapacitor electrodes

    SciTech Connect

    Malak-Polaczyk, A.; Matei-Ghimbeu, C.; Vix-Guterl, C.; Frackowiak, E.

    2010-04-15

    In the present work a composite of carbon with lambda-MnO{sub 2} have been synthesized by a simple two-step route. In the first step, to obtain LiMn{sub 2}O{sub 4}/carbon material, mesoporous activated carbon was impregnated with the solution of precursor metal salts and heated subsequently. As-prepared materials were acid treated which resulted in the formation of lambda-MnO{sub 2}/carbon. Physical properties, structure and specific surface area of electrode materials were studied by TEM, X-ray diffraction and nitrogen sorption measurements. Voltammetry cycling, galvanostatic charge/discharge and impedance spectroscopy measurements performed in two- and three-electrode cells have been applied in order to measure electrochemical parameters. TEM images confirmed well dispersed lambda-MnO{sub 2} particles on the surface of carbon material. The carbon in the composite plays an important role as the surface area enhancing component and a support of pseudocapacitive material. Furthermore, the through-connected porosity serves as a continuous pathway for electrolyte transport. A synergetic effect of the porous carbon framework and of the redox properties of the lambda-MnO{sub 2} is at the origin of improvement of specific capacitance values which has been observed for composites after delithiation. - Comparison of capacitance characteristics for initial carbon and synthesised composites for CB in 1 mol L{sup -1} Na{sub 2}SO{sub 4} solution.

  10. Application of Carbon Nanomaterials in Lithium-Ion Battery Electrodes

    NASA Astrophysics Data System (ADS)

    Jaber-Ansari, Laila

    Carbon nanomaterials such as single-walled carbon nanotubes (SWCNTs) and graphene have emerged as leading additives for high capacity nanocomposite lithium ion battery electrodes due to their ability to improve electrode conductivity, current collection efficiency, and charge/discharge rate for high power applications. In this work, the these nanomaterials have been developed and their properties have been fine-tuned to help solve fundamental issues in conventional lithium ion battery electrodes. Towards this end, the application of SWCNTs in lithium-ion anodes has been studied. As-grown SWCNTs possess a distribution of physical and electronic structures, and it is of high interest to determine which subpopulations of SWCNTs possess the highest lithiation capacity and to develop processing methods that can enhance the lithiation capacity of underperforming SWCNT species. Towards this end, SWCNT electronic type purity is controlled via density gradient ultracentrifugation, enabling a systematic study of the lithiation of SWCNTs as a function of metal versus semiconducting content. Experimentally, vacuum filtered freestanding films of metallic SWCNTs are found to accommodate lithium with an order of magnitude higher capacity than their semiconducting counterparts. In contrast, SWCNT film densification leads to the enhancement of the lithiation capacity of semiconducting SWCNTs to levels comparable to metallic SWCNTs, which is corroborated by theoretical calculations. To understand the interaction of the graphene with lithium ions and electrolyte species during electrochemical we use Raman spectroscopy in a model system of monolayer graphene transferred on a Si(111) substrate and density functional theory (DFT) to investigate defect formation as a function of lithiation. This model system enables the early stages of defect formation to be probed in a manner previously not possible with commonly-used reduced graphene oxide or multilayer graphene substrates. Using ex

  11. Industrial applications of multiaxial warp knit composites

    NASA Technical Reports Server (NTRS)

    Kaufmann, James R.

    1992-01-01

    Over the past few years, multiaxial warp knit (MWK) fabrics have made significant inroads into the industrial composites arena. This paper examines the use of MWK fabrics in industrial composite applications. Although the focus is on current applications of MWK fabrics in composites, this paper also discusses the physical properties, advantages and disadvantages of MWK fabrics. The author also offers possibilities for the future of MWK fabrics in the industrial composites arena.

  12. Method of making composition suitable for use as inert electrode having good electrical conductivity and mechanical properties

    DOEpatents

    Ray, S.P.; Rapp, R.A.

    1986-04-22

    An improved inert electrode composition is suitable for use as an inert electrode in the production of metals such as aluminum by the electrolytic reduction of metal oxide or metal salt dissolved in a molten salt bath. The composition comprises one or more metals or metal alloys and metal compounds which may include oxides of the metals comprising the alloy. The alloy and metal compounds are interwoven in a network which provides improved electrical conductivity and mechanical strength while preserving the level of chemical inertness necessary for such an electrode to function satisfactorily. 8 figs.

  13. Method of making composition suitable for use as inert electrode having good electrical conductivity and mechanical properties

    DOEpatents

    Ray, Siba P.; Rapp, Robert A.

    1986-01-01

    An improved inert electrode composition is suitable for use as an inert electrode in the production of metals such as aluminum by the electrolytic reduction of metal oxide or metal salt dissolved in a molten salt bath. The composition comprises one or more metals or metal alloys and metal compounds which may include oxides of the metals comprising the alloy. The alloy and metal compounds are interwoven in a network which provides improved electrical conductivity and mechanical strength while preserving the level of chemical inertness necessary for such an electrode to function satisfactorily.

  14. Optimized spherical manganese oxide-ferroferric oxide-tin oxide ternary composites as advanced electrode materials for supercapacitors

    NASA Astrophysics Data System (ADS)

    Zhu, Jian; Tang, Shaochun; Vongehr, Sascha; Xie, Hao; Meng, Xiangkang

    2015-09-01

    Inexpensive MnO2 is a promising material for supercapacitors (SCs), but its application is limited by poor electrical conductivity and low specific surface area. We design and fabricate hierarchical MnO2-based ternary composite nanostructures showing superior electrochemical performance via doping with electrochemically active Fe3O4 in the interior and electrically conductive SnO2 nanoparticles in the surface layer. Optimization composition results in a MnO2-Fe3O4-SnO2 composite electrode material with 5.9 wt.% Fe3O4 and 5.3 wt.% SnO2, leading to a high specific areal capacitance of 1.12 F cm-2 at a scan rate of 5 mV s-1. This is two to three times the values for MnO2-based binary nanostructures at the same scan rate. The low amount of SnO2 almost doubles the capacitance of porous MnO2-Fe3O4 (before SnO2 addition), which is attributed to an improved conductivity and remaining porosity. In addition, the optimal ternary composite has a good rate capability and an excellent cycling performance with stable capacitance retention of ˜90% after 5000 charge/discharge cycles at 7.5 mA cm-2. All-solid-state SCs are assembled with such electrodes using polyvinyl alcohol/Na2SO4 electrolyte. An integrated device made by connecting two identical SCs in series can power a light-emitting diode indicator for more than 10 min.

  15. Optimized spherical manganese oxide-ferroferric oxide-tin oxide ternary composites as advanced electrode materials for supercapacitors.

    PubMed

    Zhu, Jian; Tang, Shaochun; Vongehr, Sascha; Xie, Hao; Meng, Xiangkang

    2015-09-18

    Inexpensive MnO2 is a promising material for supercapacitors (SCs), but its application is limited by poor electrical conductivity and low specific surface area. We design and fabricate hierarchical MnO2-based ternary composite nanostructures showing superior electrochemical performance via doping with electrochemically active Fe3O4 in the interior and electrically conductive SnO2 nanoparticles in the surface layer. Optimization composition results in a MnO2-Fe3O4-SnO2 composite electrode material with 5.9 wt.% Fe3O4 and 5.3 wt.% SnO2, leading to a high specific areal capacitance of 1.12 F cm(-2) at a scan rate of 5 mV s(-1). This is two to three times the values for MnO2-based binary nanostructures at the same scan rate. The low amount of SnO2 almost doubles the capacitance of porous MnO2-Fe3O4 (before SnO2 addition), which is attributed to an improved conductivity and remaining porosity. In addition, the optimal ternary composite has a good rate capability and an excellent cycling performance with stable capacitance retention of ~90% after 5000 charge/discharge cycles at 7.5 mA cm(-2). All-solid-state SCs are assembled with such electrodes using polyvinyl alcohol/Na2SO4 electrolyte. An integrated device made by connecting two identical SCs in series can power a light-emitting diode indicator for more than 10 min. PMID:26314271

  16. PEDOT:PSS as multi-functional composite material for enhanced Li-air-battery air electrodes

    NASA Astrophysics Data System (ADS)

    Yoon, Dae Ho; Yoon, Seon Hye; Ryu, Kwang-Sun; Park, Yong Joon

    2016-01-01

    We propose PEDOT:PSS as a multi-functional composite material for an enhanced Li-air-battery air electrode. The PEDOT:PSS layer was coated on the surface of carbon (graphene) using simple method. A electrode containing PEDOT:PSS-coated graphene (PEDOT electrode) could be prepared without binder (such as PVDF) because of high adhesion of PEDOT:PSS. PEDOT electrode presented considerable discharge and charge capacity at all current densities. These results shows that PEDOT:PSS acts as a redox reaction matrix and conducting binder in the air electrode. Moreover, after cycling, the accumulation of reaction products due to side reaction in the electrode was significantly reduced through the use of PEDOT:PSS. This implies that PEDOT:PSS coating layer can suppress the undesirable side reactions between the carbon and electrolyte (and/or Li2O2), which causes enhanced Li-air cell cyclic performance.

  17. PEDOT:PSS as multi-functional composite material for enhanced Li-air-battery air electrodes

    PubMed Central

    Yoon, Dae Ho; Yoon, Seon Hye; Ryu, Kwang-Sun; Park, Yong Joon

    2016-01-01

    We propose PEDOT:PSS as a multi-functional composite material for an enhanced Li-air-battery air electrode. The PEDOT:PSS layer was coated on the surface of carbon (graphene) using simple method. A electrode containing PEDOT:PSS-coated graphene (PEDOT electrode) could be prepared without binder (such as PVDF) because of high adhesion of PEDOT:PSS. PEDOT electrode presented considerable discharge and charge capacity at all current densities. These results shows that PEDOT:PSS acts as a redox reaction matrix and conducting binder in the air electrode. Moreover, after cycling, the accumulation of reaction products due to side reaction in the electrode was significantly reduced through the use of PEDOT:PSS. This implies that PEDOT:PSS coating layer can suppress the undesirable side reactions between the carbon and electrolyte (and/or Li2O2), which causes enhanced Li-air cell cyclic performance. PMID:26813852

  18. Fabrication of a nano-structured PbO2 electrode by using printing technology: Surface characterization and application

    NASA Astrophysics Data System (ADS)

    Kannan, K.; Muthuraman, G.; Cho, G.; Moon, I. S.

    2014-08-01

    This investigation aimed to introduce printing technology for the first time to prepare a nanostrucutured PbO2 electrode and its application to a cerium redox transfer process. The new method of nano-size PbO2 preparation demonstrated that nano-PbO2 could be obtained in less time and at less cost at room temperature. The prepared nano-PbO2 screen printed on a Ti electrode by three different compositions under similar conditions showed through surface and electrochemical analyses no adherence on Ti and no contact with other nano-PbO2 particles. Gravure printing of nano-PbO2 on a PET (poly ethylene thin) film at high pressure was done with two different compositions for the first time. The selective composition of 57.14 % nano-PbO2 powder with 4.28 % carbon black and 38.58 % ECA (ethyl carbitol acetate) produced a film with a nanoporous structure with an electron transfer ability. Finally, the optimized gravure-printed nano-PbO2 electrode was applied to the oxidation of Ce(III) to Ce(IV) by using cyclic voltammetry. The gravure-printed nano-PbO2 should pave the way to promising applications in electrochemical and sensor fields.

  19. Application of Carbon Nanomaterials in Lithium-Ion Battery Electrodes

    NASA Astrophysics Data System (ADS)

    Jaber-Ansari, Laila

    Carbon nanomaterials such as single-walled carbon nanotubes (SWCNTs) and graphene have emerged as leading additives for high capacity nanocomposite lithium ion battery electrodes due to their ability to improve electrode conductivity, current collection efficiency, and charge/discharge rate for high power applications. In this work, the these nanomaterials have been developed and their properties have been fine-tuned to help solve fundamental issues in conventional lithium ion battery electrodes. Towards this end, the application of SWCNTs in lithium-ion anodes has been studied. As-grown SWCNTs possess a distribution of physical and electronic structures, and it is of high interest to determine which subpopulations of SWCNTs possess the highest lithiation capacity and to develop processing methods that can enhance the lithiation capacity of underperforming SWCNT species. Towards this end, SWCNT electronic type purity is controlled via density gradient ultracentrifugation, enabling a systematic study of the lithiation of SWCNTs as a function of metal versus semiconducting content. Experimentally, vacuum filtered freestanding films of metallic SWCNTs are found to accommodate lithium with an order of magnitude higher capacity than their semiconducting counterparts. In contrast, SWCNT film densification leads to the enhancement of the lithiation capacity of semiconducting SWCNTs to levels comparable to metallic SWCNTs, which is corroborated by theoretical calculations. To understand the interaction of the graphene with lithium ions and electrolyte species during electrochemical we use Raman spectroscopy in a model system of monolayer graphene transferred on a Si(111) substrate and density functional theory (DFT) to investigate defect formation as a function of lithiation. This model system enables the early stages of defect formation to be probed in a manner previously not possible with commonly-used reduced graphene oxide or multilayer graphene substrates. Using ex

  20. Laser annealed composite titanium dioxide electrodes for dye-sensitized solar cells on glass and plastics

    NASA Astrophysics Data System (ADS)

    Pan, Heng; Ko, Seung Hwan; Misra, Nipun; Grigoropoulos, Costas P.

    2009-02-01

    We report a rapid and low temperature process for fabricating composite TiO2 electrodes for dye-sensitized solar cells on glass and plastics by in tandem spray deposition and laser annealing. A homogenized KrF excimer laser beam (248 nm) was used to layer-by-layer anneal spray deposited TiO2 nanoparticles. The produced TiO2 film is crack free and contains small particles (30 nm) mixed with different fractions of larger particles (100-200 nm) controlled by the applied laser fluence. Laser annealed double-layered structure is demonstrated for both doctor-blade deposited and spray-deposited electrodes and performance enhancement can be observed. The highest demonstrated all-laser-annealed cells utilizing ruthenium dye and liquid electrolyte showed power conversion efficiency of ˜3.8% under simulated illumination of 100 mW/cm2.

  1. Amorphous Vanadium Oxide/Carbon Composite Positive Electrode for Rechargeable Aluminum Battery.

    PubMed

    Chiku, Masanobu; Takeda, Hiroki; Matsumura, Shota; Higuchi, Eiji; Inoue, Hiroshi

    2015-11-11

    Amorphous vanadium oxide/carbon composite (V2O5/C) was first applied to the positive electrode active material for rechargeable aluminum batteries. Electrochemical properties of V2O5/C were investigated by cyclic voltammetry and charge-discharge tests. Reversible reduction/oxidation peaks were observed for the V2O5/C electrode and the rechargeable aluminum cell showed the maximum discharge capacity over 200 mAh g(-1) in the first discharging. The XPS analyses after discharging and the following charging exhibited that the redox of vanadium ion in the V2O5/C active material occurred during discharging and charging, and the average valence of V changed between 4.14 and 4.85. PMID:26489385

  2. Factors determining the packing-limitation of active materials in the composite electrode of lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Kitada, Koji; Murayama, Haruno; Fukuda, Katsutoshi; Arai, Hajime; Uchimoto, Yoshiharu; Ogumi, Zempachi; Matsubara, Eiichiro

    2016-01-01

    The factors limiting the capacity of highly dense electrodes are elucidated by using composite electrodes for lithium-ion batteries, which consist of active materials LiNi1/3Co1/3Mn1/3O2 (NCM), conductive additives and binders. Electrochemical tests of such 100-μm-thick electrodes in 1 M LiPF6 electrolyte indicate that a highly dense electrode (with 18% porosity) shows a capacity density significantly lower than the other sparse electrodes on 1C charging/discharging. Detailed analysis using position sensitive in situ X-ray diffraction indicates that, unlike the other sparse electrodes, NCM on the current-collector side barely functions for this dense electrode, due to the poor accessibility of Li+ to the inner part of the electrode. Interestingly, 2 M and 0.3 M electrolytes promote the discharge and charge reactions, respectively, over the entire area of the electrode, although they exhibit lower conductivity than the 1 M electrolyte, which indicates the importance of the initial amount of Li+ in the electrolyte impregnated in the electrode pores. Thus, for a high-energy-density cell, the initial amount of Li+ and the Li+ transport significantly affect the rate capability, which governs the practical capacity of the cell under constant-current operation.

  3. Selective removal of nitrate ion using a novel composite carbon electrode in capacitive deionization.

    PubMed

    Kim, Yu-Jin; Choi, Jae-Hwan

    2012-11-15

    We fabricated nitrate-selective composite carbon electrodes (NSCCEs) for use in capacitive deionization to remove nitrate ions selectively from a solution containing a mixture of anions. The NSCCE was fabricated by coating the surface of a carbon electrode with the anion exchange resin, BHP55, after grinding the resin into fine powder. BHP55 is known to be selective for nitrate ions. We performed desalination experiments on a solution containing 5.0 mM NaCl and 2.0 mM NaNO(3) using the NSCCE system constructed with the fabricated electrode. The selective removal of nitrate in the NSCCE system was compared to a membrane capacitive deionization (MCDI) system constructed with ion exchange membranes and carbon electrodes. The total quantity of chloride and nitrate ions adsorbed onto the unit area of the electrode in the MCDI system was 25 mmol/m(2) at a cell potential of 1.0 V. The adsorption of nitrate ions was 8.3 mmol/m(2), accounting for 33% of the total. In contrast, the total anion adsorption in the NSCCE system was 34 mmol/m(2), 36% greater than the total anion adsorption of the MCDI system. The adsorption of nitrate ions was 19 mmol/m(2), 2.3-times greater than the adsorption in the MCDI system. These results showed that the ions were initially adsorbed by an electrostatic force, and the ion exchange reactions then occurred between the resin powder in the coated layer and the solution containing mixed anions. PMID:22980574

  4. Graphene/polyaniline composite sponge of three-dimensional porous network structure as supercapacitor electrode

    NASA Astrophysics Data System (ADS)

    Jiu-Xing, Jiang; Xu-Zhi, Zhang; Zhen-Hua, Wang; Jian-Jun, Xu

    2016-04-01

    As a supercapacitor electrode, the graphene/polyaniline (PANI) composite sponge with a three-dimensional (3D) porous network structure is synthesized by a simple three-step method. The three steps include an in situ polymerization, freeze-drying and reduction by hydrazine vapor. The prepared sponge has a large specific surface area and porous network structure, so it is in favor of spreading the electrolyte ion and increasing the charge transfer efficiency of the system. The process of preparation is simple, easy to operate and low cost. The composite sponge shows better electrochemical performance than the pure individual graphene sponge while PANI cannot keep the shape of a sponge. Such a composite sponge exhibits specific capacitances of 487 F·g‑1 at 2 mV/s compared to pristine PANI of 397 F·g‑1. Project supported by the Natural Science Foundation from Harbin University of Science and Technology and Harbin Institute of Technology.

  5. Voltammetric detection of phenol at platinum-polytyramine composite electrodes in acidic media.

    PubMed

    Spătaru, Tanţa; Spătaru, Nicolae

    2010-08-15

    A composite obtained by depositing platinum nanoparticles in a polytyramine (PTy) matrix, electrochemically formed on graphite substrate, was used as electrode material for the investigation of phenol oxidation by use of anodic voltammetry. The results show that, in acidic media, the measurement of the oxidation peak current can be used as the basis for a simple, rapid method for the determination of phenol within a concentration range of 0.3-10 mM. A much better resistance to fouling during phenol detection (compared both with smooth platinum and with Pt nanoparticles on bare graphite substrate) is the main advantage of the Pt-PTy composite. These results are also noteworthy because they provide a basis for additional experiments devoted to obtaining new composite materials with improved performances for phenol anodic oxidation. PMID:20462693

  6. Nickel-cadmium batteries: effect of electrode phase composition on acid leaching process.

    PubMed

    Nogueira, C A; Margarido, F

    2012-01-01

    At the end of their life, Ni-Cd batteries cause a number of environmental problems because of the heavy metals they contain. Because of this, recycling of Ni-Cd batteries has been carried out by dedicated companies using, normally, pyrometallurgical technologies. As an alternative, hydrometallurgical processes have been developed based on leaching operations using several types of leachants. The effect of factors like temperature, acid concentration, reaction time, stirring speed and grinding of material on the leaching yields of metals contained in anodic and cathodic materials (nickel, cadmium and cobalt) using sulphuric acid, is herein explained based on the structural composition of the electrode materials. The nickel, cobalt and cadmium hydroxide phases, even with a small reaction time (less than 15 minutes) and low temperature (50 degrees C) and acid concentration (1.1 M H2SO4), were efficiently leached. However, leaching of the nickel metallic phase was more difficult, requiring higher values of temperature, acid concentration and reaction time (e.g. 85 degrees C, 1.1 M H2SO4 and 5 h, respectively) in order to obtain a good leaching efficiency for anodic and cathodic materials (70% and 93% respectively). The stirring speed was not significant, whereas the grinding of electrode materials seems to promote the compaction of particles, which appears to be critical in the leaching of Ni degrees. These results allowed the identification and understanding of the relationship between the structural composition of electrode materials and the most important factors that affect the H2SO4 leaching of spent Ni-Cd battery electrodes, in order to obtain better metal-recovery efficiency. PMID:22519122

  7. Chemical Modification of Boron-Doped Diamond Electrodes for Applications to Biosensors and Biosensing.

    PubMed

    Svítková, Jana; Ignat, Teodora; Švorc, Ľubomír; Labuda, Ján; Barek, Jiří

    2016-05-01

    Boron-doped diamond (BDD) is a prospective electrode material that possesses many exceptional properties including wide potential window, low noise, low and stable background current, chemical and mechanical stability, good biocompatibility, and last but not least exceptional resistance to passivation. These characteristics extend its usability in various areas of electrochemistry as evidenced by increasing number of published articles over the past two decades. The idea of chemically modifying BDD electrodes with molecular species attached to the surface for the purpose of creating a rational design has found promising applications in the past few years. BDD electrodes have appeared to be excellent substrate materials for various chemical modifications and subsequent application to biosensors and biosensing. Hence, this article presents modification strategies that have extended applications of BDD electrodes in electroanalytical chemistry. Different methods and steps of surface modification of this electrode material for biosensing and construction of biosensors are discussed. PMID:26337147

  8. Synthesis of graphene oxide based CuO nanoparticles composite electrode for highly enhanced nonenzymatic glucose detection.

    PubMed

    Song, Jian; Xu, Lin; Zhou, Chunyang; Xing, Ruiqing; Dai, Qilin; Liu, Dali; Song, Hongwei

    2013-12-26

    CuO nanoparticles (NPs) based graphene oxide (CuO/GO) composites with different CuO NPs loading amount as well as pure CuO NPs with different hydrothermal temperatures were synthesized using a hydrothermal method. Transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and Raman spectroscopy were employed to characterize the morphology and structures of our samples. The influence of hydrothermal temperature, GO sheet, and loading amount of CuO on particle size and structure of CuO was systemically investigated. The nonenzymatic biosensing properties of CuO/GO composites and CuO NPs toward glucose were studied based on glassy carbon electrode (GCE). The sensing properties of CuO NPs were improved after loading on GO sheets. The CuO/GO composites with saturated loading of the CuO NPs exhibited the best nonenzymatic biosensing behavior. It exhibited a sensitivity of 262.52 μA mM(-1) cm(-2) to glucose with a 0.69 μM detection limit (S/N = 3) and a linear range from 2.79 μM to 2.03 mM under a working potential of +0.7 V. It also showed outstanding long term stability, good reproducibility, excellent selectivity, and accurate measurement in real serum sample. It is believed that CuO/GO composites show good promise for further application on nonenzymatic glucose biosensors. PMID:24182328

  9. Cerium-modified doped strontium titanate compositions for solid oxide fuel cell anodes and electrodes for other electrochemical devices

    DOEpatents

    Marina, Olga A [Richland, WA; Stevenson, Jeffry W [Richland, WA

    2010-03-02

    The present invention provides novel compositions that find advantageous use in making electrodes for electrochemical cells and electrochemical devices such as solid oxide fuel cells, electrolyzers, sensors, pumps and the like, the compositions comprising cerium-modified doped strontium titanate. The invention also provides novel methods for making and using anode material compositions and solid oxide fuel cells and solid oxide fuel cell assemblies having anodes comprising the compositions.

  10. Cerium-modified doped strontium titanate compositions for solid oxide fuel cell anodes and electrodes for other electrochemical devices

    DOEpatents

    Marina, Olga A [Richland, WA; Stevenson, Jeffry W [Richland, WA

    2010-11-23

    The present invention provides novel compositions that find advantageous use in making electrodes for electrochemical cells and electrochemical devices such as solid oxide fuel cells, electrolyzers, sensors, pumps and the like, the compositions comprising cerium-modified doped strontium titanate. The invention also provides novel methods for making and using anode material compositions and solid oxide fuel cells and solid oxide fuel cell assemblies having anodes comprising the compositions.

  11. [Preparation and Pb2 electrosorption characteristics of MnO2/CFP composite electrode].

    PubMed

    Liu, Fang-Yuan; Hu, Cheng-Zhi; Li, Yong-Feng; Liang, Qian-Wei

    2015-02-01

    The morphological structure and electrochemical properties of the electrode materials have direct impact on the electrosorption results. In this paper, Manganese dioxide ( MnO2) was composed on flexible carbon fiber paper ( CFP) via anodic electrodeposition technique to prepare the MnO2/CFP hybrid electrodes. The electrodes materials prepared showed stable electrochemical property, remarkable electrochemical capacitance, and the specific capacitance reached up to 360 F x g(-1). Electrosorption was conducted with this MnO2/CFP hybrid electrode to treat the waste water with an initial Pb2+ concentration of 6 mg x L(-1), and the effects of deposition time, initial pH, and voltage value on the electrosorption were investigated. It was shown that when the electrodeposition time was 500 s and the application of voltage value was 1.0 V, pH = 5.0, the best electroabsorption result was achieved. After 3 h electrosorption, the residual Pb2+ in the solution was lower than 0.01 mg x L(-1), and the removal efficiency could reach 99%. This study provides a new technology option for the removal of heavy metal ions in low concentrations in the waste water. PMID:26031082

  12. Application of gas diffusion electrodes in bioelectrochemical syntheses and energy conversion.

    PubMed

    Horst, Angelika E W; Mangold, Klaus-Michael; Holtmann, Dirk

    2016-02-01

    Combining the advantages of biological components (e.g., reaction specificity, self-replication) and electrochemical techniques in bioelectrochemical systems offers the opportunity to develop novel efficient and sustainable processes for the production of a number of valuable products. The choice of electrode material has a great impact on the performance of bioelectrochemical systems. In addition to the redox process at the electrodes, interactions of biocatalysts with electrodes (e.g., enzyme denaturation or biofouling) need to be considered. In recent years, gas diffusion electrodes (GDEs) have proved to be very attractive electrodes for bioelectrochemical purposes. GDEs are porous electrodes, that posses a large three-phase boundary surface. At this interface, a solid catalyst supports the electrochemical reaction between gaseous and liquid phase. This mini-review discusses the application of GDEs in microbial and enzymatic fuel cells, for microbial electrolysis, in biosensors and for electroenzymatic synthesis reactions. PMID:26152235

  13. Electrodes for bio-application: recording and stimulation

    NASA Astrophysics Data System (ADS)

    Fontes, M. B. A.

    2013-03-01

    Recording and stimulation electrodes applied on excitable tissue are the basis of electrophysiological research, such as brain, muscles, peripheral nerves or sensory systems. Electrode-electrolyte impedance is one of the important characteristics due to its influence on the signal/noise ratio, signal distortion and built-up voltage. Strategies to lowering and tuning the impedance are achieved by biasing iridium oxide modified platinum microelectrodes. Surface and impedance analysis after pulse stimulation are also addressed.

  14. Preparation, applications, and digital simulation of carbon interdigitated array electrodes.

    PubMed

    Liu, Fei; Kolesov, Grigory; Parkinson, B A

    2014-08-01

    Carbon interdigitated array (IDA) electrodes with features sizes down to 1.2 μm were fabricated by controlled pyrolysis of patterned photoresist. Cyclic voltammetry of reversible redox species produced the expected steady-state currents. The collection efficiency depends on the IDA electrode spacing, which ranged from around 2.7 to 16.5 μm, with the smaller dimensions achieving higher collection efficiencies of up to 98%. The signal amplification because of redox cycling makes it possible to detect species at relatively low concentrations (10(-5) molar) and the small spacing allows detection of transient electrogenerated species with much shorter lifetimes (submillisecond). Digital simulation software that accounts for both the width and height of electrode elements as well as the electrode spacing was developed to model the IDA electrode response. The simulations are in quantitative agreement with experimental data for both a simple fast one electron redox reaction and an electron transfer with a following chemical reaction at the IDAs with larger gaps whereas currents measured for the smallest IDA electrodes, that were larger than the simulated currents, are attributed to convection from induced charge electrokinetic flow. PMID:24998907

  15. Preparation, Applications, and Digital Simulation of Carbon Interdigitated Array Electrodes

    SciTech Connect

    Liu, Fei; Kolesov, Grigory; Parkinson, Bruce A.

    2014-12-16

    Carbon interdigitated array (IDA) electrodes with features sizes down to 1.2 μm were fabricated by controlled pyrolysis of patterned photoresist. Cyclic voltam-metry of reversible redox species produced the expected steady-state currents. The collection efficiency depends on the IDA electrode spacing, which ranged from around 2.7 to 16.5 μm, with the smaller dimensions achieving higher collection efficiencies of up to 98%. The signal amplification because of redox cycling makes it possible to detect species at relatively low concentrations (10–5 molar) and the small spacing allows detection of transient electrogenerated species with much shorter lifetimes (submillisecond). Digital simulation software that accounts for both the width and height of electrode elements as well as the electrode spacing was developed to model the IDA electrode response. The simulations are in quantitative agreement with experimental data for both a simple fast one electron redox reaction and an electron transfer with a following chemical reaction at the IDAs with larger gaps whereas currents measured for the smallest IDA electrodes, that were larger than the simulated currents, are attributed to convection from induced charge electrokinetic flow. This work was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the Department of Energy, Office of Science Office of Basic Energy Sciences.

  16. Electrode Build-Up of Reducible Metal Composites toward Achievable Electrochemical Conversion of Carbon Dioxide.

    PubMed

    Lee, Seunghwa; Lee, Jaeyoung

    2016-02-19

    At the beginning of the 21st century, our world is faced with a global-warming problem due to the continuous increase in carbon dioxide emission, and thus, the development of novel experimental techniques is needed. The electrochemical conversion of carbon dioxide into high-value organic compounds could be of vital importance to solve this issue. The biggest challenge has always been to develop an electrocatalyst that is chemically active and structurally stable. Herein, previous studies, recent approaches, and current points of view on the electrode structure of metal oxide composites for the advanced electrochemical conversion of carbon dioxide are reviewed. PMID:26610065

  17. Stabilized composite membranes and membrane electrode assemblies for elevated temperature/low relative humidity PEFC operation

    NASA Astrophysics Data System (ADS)

    Ramani, Vijay; Kunz, H. R.; Fenton, J. M.

    An approach is presented to combine existing heteropolyacid (HPA) additive and membrane electrode assembly (MEA) stabilization techniques to yield a stabilized MEA for operation at 120 °C and 35% relative humidity (RH). MEAs were prepared using Nafion ®/phosphotungstic acid composite membranes with a phosphotungstic acid (PTA) particle size of 30-50 nm. The PTA additive was stabilized by substituting its protons with cesium counter ions. The Nafion ® in the membrane and electrodes was simultaneously converted to the Cs + form by an ion-exchange process. The melt processability of the Nafion ® in the Cs + form permitted the MEA to be heat treated at 200 °C and 30 atm, promoting the development of a durable membrane/electrode interface. The prior stabilization of the PTA permitted MEA re-protonation with minimal additive loss. FTIR spectroscopy and thermogravimetric analysis (TGA) were employed to present evidence of ion-exchange and protonation. In situ electrochemical impedance measurements (EIS) and cyclic voltammetry (CV) measurements confirmed ion-exchange and protonation within the active portion of the stabilized MEA. The stabilization process did not affect the integrity of the MEA, with the hydrogen crossover currents through the membrane remaining unchanged at 2 mA cm -2. The MEA was evaluated at 120 °C and 35% relative humidity in an operating fuel cell environment and yielded respectable performance under these conditions.

  18. Manufacturing of industry-relevant silicon negative composite electrodes for lithium ion-cells

    NASA Astrophysics Data System (ADS)

    Nguyen, B. P. N.; Chazelle, S.; Cerbelaud, M.; Porcher, W.; Lestriez, B.

    2014-09-01

    In this paper, Poly (acrylic-co-maleic) acid (PAMA) is used as a dispersant to improve the stability of electrodes slurries for large scale processing of Silicon based negative composite electrode. The stability and homogeneity of the slurries are characterized using different techniques. Sedimentation test, electrical measurement, SEM-EDX observations as well as rheological measurements show that a more homogeneous distribution of carbon black (CB) inside the stack of Si particles is reached with presence of PAMA. However, the amount of PAMA is limited due to the competition in the adsorption of PAMA and Carboxylmethyl cellulose (CMC) at the surface of the CB particles. Upon cycling with capacity limitation, the optimized electrode formulation at lab scale could achieve more than 400 cycles with surface capacity ∼2.5-3.3 mAh cm-2. At the pilot scale, the improvement of adhesion of the tape to the current collector by using Styrene-co-Butadiene rubber copolymer latex (SB) helps to maintain long cycle life while calendaring is detrimental to electrochemical properties.

  19. Portable Bioimpedance Spectroscopy device and textile electrodes for mobile monitoring applications

    NASA Astrophysics Data System (ADS)

    Beckmann, L.; Jacob, M.; Hoog Antink, C.; Cordes, A.; Pikkemaat, R.; Jungbecker, N.; Gries, T.; Leonhardt, S.

    2010-04-01

    A balanced body composition is necessary for a person's health and performance. Therefore, it is important to control the body composition continuously since complications and diseases due to dehydration often appear gradually. Based on these facts a miniaturized mobile Bioimpedance Spectroscopy device was developed that can be integrated into clothing and allows the continuous monitoring of a person's body water. The implemented system has been tested using different body models. The first measurements showed very precise and stable results. Besides the portable measurement system, textile electrodes are needed for continuous long term monitoring. Therefore, special textile electrodes were developed, tested and evaluated. The electrodes are structured in a specific way leading to a rougher surface. Such a surface improves the interface impedance and therefore optimizes the connection between electronic hardware and body. For comparison, five different structured electrodes were manufactured and tested on a special test setup that allows reproducible interface-impedance measurements using a dummy made of agar-agar to simulate the skin. It could be shown that the surface structure significantly influences the interface impedance in a positive way as compared to standard plane textile electrodes. In the future, a combination of the miniaturized BIS electronic and the structured textile electrodes could allow reproducible long term monitoring of a person's body composition.

  20. Enhanced photovoltaic performance of dye-sensitized solar cell using composite photoanode on 3D electrode

    NASA Astrophysics Data System (ADS)

    Lim, Chiew Keat; Huang, Hui; Tse, Man Siu; Tan, Ooi Kiang

    2013-12-01

    For dye-sensitized solar cell (DSSC), an efficient transport of electron from the dye sensitizer through the mesoporous oxide layer and to be collected by electrode is crucial for high photovoltaic conversion efficiency. In this work, two novel approaches were developed in DSSC fabrication to improve the overall photovoltaic performance. The concurrent improvement in the charge transport property and light harvesting efficiency was achieved by incorporating N-doped TiO2 in the mesoporous TiO2 layer of the photoanode. These N-doped TiO2 (TiNxOy) was formed by using the single step thermal oxidation of Titanium Nitride (TiN) nanomaterials. At the same time, the 3D electrode with SnO2 nanorods grown on the FTO glass using plasma enhanced chemical vapor deposition (PECVD) system was used to enhance the charge collection efficiency. By combining these two approaches simultaneously, the DSSC with composite TiNxOy-TiO2 photoanode on SnO2 nanorods 3D electrode was successfully fabricated and characterized. As compared to the standard DSSC, an overall increment of 28 % in the conversion efficiency was achieved. Higher incident photon-current conversion efficiency (IPCE) values were also obtained, specifically for the region 400 - 500 nm due to the cosensitization effect of N-doped TiO2. Efficient transfer of electron due to the decrease in charge transfer resistance at the mesoporous oxide/dye/electrolyte interface was observed from electrochemical impedance spectroscopy (EIS) measurement. With the use of SnO2 nanorods, the adhesion between the mesoporous TiO2/FTO was enhanced and the transit time of a photogenerated electron through the mesoporous layer before being collected at the FTO electrode was significantly reduced by 50 %.

  1. The application of graphene as electrodes in electrical and optical devices

    NASA Astrophysics Data System (ADS)

    Jo, Gunho; Choe, Minhyeok; Lee, Sangchul; Park, Woojin; Kahng, Yung Ho; Lee, Takhee

    2012-03-01

    Graphene is a promising next-generation conducting material with the potential to replace traditional electrode materials such as indium tin oxide in electrical and optical devices. It combines several advantageous characteristics including low sheet resistance, high optical transparency and excellent mechanical properties. Recent research has coincided with increased interest in the application of graphene as an electrode material in transistors, light-emitting diodes, solar cells and flexible devices. However, for more practical applications, the performance of devices should be further improved by the engineering of graphene films, such as through their synthesis, transfer and doping. This article reviews several applications of graphene films as electrodes in electrical and optical devices and discusses the essential requirements for applications of graphene films as electrodes.

  2. Electrochemical properties of graphene nanosheets/polyaniline nanofibers composites as electrode for supercapacitors

    NASA Astrophysics Data System (ADS)

    Li, Jing; Xie, Huaqing; Li, Yang; Liu, Jie; Li, Zhuxin

    Graphene nanosheets/polyaniline nanofibers (GNS/PANI) composites are synthesized via in situ polymerization of aniline monomer in HClO 4 solution. The PANI nanofibers homogeneously coating on the surface of GNS greatly improve the charge transfer reaction. The GNS/PANI composites exhibit better electrochemical performances than the pure individual components. A remarkable specific capacitance of 1130 F g -1 (based on GNS/PANI composites) is obtained at a scan rate of 5 mV s -1 in 1 M H 2SO 4 solution compared to 402 F g -1 for pure PANI and 270 F g -1 for GNS. The excellent performance is not only due to the GNS which can provide good electrical conductivity and high specific surface area, but also associate with a good redox activity of ordered PANI nanofibers. Moreover, the GNS/PANI composites present excellent long cycle life with 87% specific capacitance retained after 1000 charge/discharge processes. The resulting composites are promising electrode materials for high-performance electrical energy storage devices.

  3. Graphene/vanadium oxide nanotubes composite as electrode material for electrochemical capacitors

    NASA Astrophysics Data System (ADS)

    Fu, Meimei; Ge, Chongyong; Hou, Zhaohui; Cao, Jianguo; He, Binhong; Zeng, Fanyan; Kuang, Yafei

    2013-07-01

    Graphene/vanadium oxide nanotubes (VOx-NTs) composite was successfully synthesized through the hydrothermal process in which acetone as solvent and 1-hexadecylamine (HDA) as structure-directing template were used. Morphology, structure and composition of the as-obtained composite were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, nitrogen isothermal adsorption/desorption and thermo gravimetric analysis (TGA). The composite with the VOx-NTs amount of 69.0 wt% can deliver a specific capacitance of 210 F/g at a current density of 1 A/g in 1 M Na2SO4 aqueous solution, which is nearly twice as that of pristine graphene (128 F/g) or VOx-NTs (127 F/g), and exhibit a good performance rate. Compared with pure VOx-NTs, the cycle stability of the composite was also greatly improved due to the enhanced conductivity of the electrode and the structure buffer role of graphene.

  4. Design architecture of double spiral interdigitated electrode with back gate electrode for biosensor application

    NASA Astrophysics Data System (ADS)

    Fathil, M. F. M.; Arshad, M. K. Md.; Hashim, U.; Ruslinda, A. R.; Gopinath, Subash C. B.; M. Nuzaihan M., N.; Ayub, R. M.; Adzhri, R.; Zaki, M.; Azman, A. H.

    2016-07-01

    This paper presents the preparation method of photolithography chrome mask design used in fabrication process of double spiral interdigitated electrode with back gate biasing based biosensor. By learning the fabrication process flow of the biosensor, the chrome masks are designed through drawing using the AutoCAD software. The overall width and length of the device is optimized at 7.0 mm and 10.0 mm, respectively. Fabrication processes of the biosensor required three chrome masks, which included back gate opening, spiral IDE formation, and passivation area formation. The complete chrome masks design will be sent for chrome mask fabrication and for future use in biosensor fabrication.

  5. Fe3O4/carbon coated silicon ternary hybrid composite as supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Oh, Ilgeun; Kim, Myeongjin; Kim, Jooheon

    2015-02-01

    In this study, Fe3O4/carbon-coated Si ternary hybrid composites were fabricated. A carbon layer was directly formed on the surface of Si by the thermal vapor deposition. The carbon-coating layer not only prevented the contact between Si and reactive electrolyte but also provided anchoring sites for the deposition of Fe3O4. Fe3O4 nanoparticles were deposited on the surface of carbon-coated Si by the hydrazine reducing method. The morphology and structure of Fe3O4 and carbon layer were characterized via X-ray diffractometry, field emission scanning electron microscopy, field emission transmission electron microscopy, X-ray photoelectron spectroscopy, and thermogravimetric analyses. These characterizations indicate that a carbon layer was fully coated on the Si particles, and Fe3O4 particles were homogeneously deposited on the carbon-coated Si particles. The Fe3O4/carbon-coated Si electrode exhibited enhanced electrochemical performance, attributed to the high conductivity and stability of carbon layer and pseudocapacitive reaction of Fe3O4. The proposed ternary-hybrid composites may be potentially useful for the fabrication of high-performance electrodes.

  6. Thermoplastic composites for ballistic application

    NASA Astrophysics Data System (ADS)

    Song, John Whachong

    2003-08-01

    Systematic studies of thermoplastic composites on ballistic impact failure and kinetic energy absorption mechanisms were examined on both semicrystalline and amorphous polymer matrix composites. By taking advantages of the nature of thermoplastic polymers, the main objective of this research was to develop armor grade composites with thermoplastic resin matrices through a understanding of the microscopic as well as macroscopic characteristics of the composites. In both semicrystalline neat resin and composites, the crystal formation and the degree of crystallinity of the polymer matrix were greatly influenced by processing conditions, especially, the cooling rate. As the cooling rate is decreased, more perfect crystal formation and amorphous rearrangements were evident vs cooling at higher rates. The relative degree of crystallinity of semicrystalline matrix composites was calculated using dynamic mechanical analysis (DMA). These values were in good agreement with neat resin values obtained via differantial scanning calorimeter (DSC). Unfortunately, the morphological perfection of the semicrystalline matrix exhibits negligible advantage on ballistic impact resistance. Failure of the composites under ballistic impact was localized and the kinetic energy absorption was low. Amorphous polymers were also greatly influenced by processing conditions. Furthermore, amorphous polymers exhibit large processing windows in terms of processing temperature, which allows the various processing manipulations for ballistic composite fabrication. As increasing processing temperature, glass transition temperature of the polymer and stiffness of the composite increased due to the morphological perfection and level of wetting, respectively. Ballistic impact resistance was found to be inversely proportional to the stiffness of the composites. Fiber wetting characteristics and polymer morphology changes during the cooling process are considered to be major contributors of this behavior

  7. Electromechanical model for a self-sensing ionic polymer-metal composite actuating device with patterned surface electrodes

    NASA Astrophysics Data System (ADS)

    Kruusamäe, Karl; Brunetto, Paola; Punning, Andres; Kodu, Margus; Jaaniso, Raivo; Graziani, Salvatore; Fortuna, Luigi; Aabloo, Alvo

    2011-12-01

    This paper further discusses a concept of creating a self-sensing ionic polymer-metal composite (IPMC) actuating device with patterned surface electrodes where the actuator and sensor elements are separated by a grounded shielding electrode. Different patterning methods are discussed and compared in detail; the presented experimental data give an understanding of the qualitative properties of the patterns created. Finally, an electromechanical model of the device is proposed and validated.

  8. Novel semi-dry electrodes for brain–computer interface applications

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Li, Guangli; Chen, Jingjing; Duan, Yanwen; Zhang, Dan

    2016-08-01

    Objectives. Modern applications of brain–computer interfaces (BCIs) based on electroencephalography rely heavily on the so-called wet electrodes (e.g. Ag/AgCl electrodes) which require gel application and skin preparation to operate properly. Recently, alternative ‘dry’ electrodes have been developed to increase ease of use, but they often suffer from higher electrode–skin impedance and signal instability. In the current paper, we have proposed a novel porous ceramic-based ‘semi-dry’ electrode. The key feature of the semi-dry electrodes is that their tips can slowly and continuously release a tiny amount of electrolyte liquid to the scalp, which provides an ionic conducting path for detecting neural signals. Approach. The performance of the proposed electrode was evaluated by simultaneous recording of the wet and semi-dry electrodes pairs in five classical BCI paradigms: eyes open/closed, the motor imagery BCI, the P300 speller, the N200 speller and the steady-state visually evoked potential-based BCI. Main results. The grand-averaged temporal cross-correlation was 0.95 ± 0.07 across the subjects and the nine recording positions, and these cross-correlations were stable throughout the whole experimental protocol. In the spectral domain, the semi-dry/wet coherence was greater than 0.80 at all frequencies and greater than 0.90 at frequencies above 10 Hz, with the exception of a dip around 50 Hz (i.e. the powerline noise). More importantly, the BCI classification accuracies were also comparable between the two types of electrodes. Significance. Overall, these results indicate that the proposed semi-dry electrode can effectively capture the electrophysiological responses and is a feasible alternative to the conventional dry electrode in BCI applications.

  9. α MnMoO₄/graphene hybrid composite: high energy density supercapacitor electrode material.

    PubMed

    Ghosh, Debasis; Giri, Soumen; Moniruzzaman, Md; Basu, Tanya; Mandal, Manas; Das, Chapal Kumar

    2014-07-28

    A unique and cost effective hydrothermal procedure has been carried out for the synthesis of hexahedron shaped α MnMoO4 and its hybrid composite with graphene using three different weight percentages of graphene. Characterization techniques, such as XRD, Raman and FTIR analysis, established the phase and formation of the composite. The electrochemical characterization of the pseudocapacitive MnMoO4 and the MnMoO4/graphene composites in 1 M Na2SO4 displayed highest specific capacitances of 234 F g(-1) and 364 F g(-1), respectively at a current density of 2 A g(-1). Unlike many other pseudocapacitive electrode materials our prepared materials responded in a wide range of working potentials of (-)1 V to (+)1 V, which indeed resulted in a high energy density without substantial loss of power density. The highest energy densities of 130 Wh kg(-1) and 202.2 Wh kg(-1) were achieved, respectively for the MnMoO4 and the MnMoO4/graphene composite at a constant power delivery rate of 2000 W kg(-1). The synergistic effect of the graphene with the pseudocapacitive MnMoO4 caused an increased cycle stability of 88% specific capacitance retention after 1000 consecutive charge discharge cycles at 8 A g(-1) constant current density, which was higher than the virgin MnMoO4 with 84% specific capacitance retention. PMID:24921461

  10. Graphene/heparin template-controlled polyaniline nanofibers composite for high energy density supercapacitor electrode

    NASA Astrophysics Data System (ADS)

    Moniruzzaman Sk, Md; Yue, Chee Yoon; Jena, Rajeeb Kumar

    2014-12-01

    Graphene/PANI nanofibers composites are prepared for the first time using a novel in situ polymerization method based on the chemical oxidative polymerization of aniline using heparin as a soft template. The even dispersion of individual graphene sheet within the polymer nanofibers matrix enhances the kinetics for both charge transfer and ion transport throughout the electrode. This novel G25PNF75 composite (weight ratio of GO:PANI = 25:75) shows a high specific capacitance of 890.79 F g-1 and an excellent energy density of 123.81 Wh kg-1 at a constant discharge current of 0.5 mA. The composite exhibits excellent cycle life with 88.78% specific capacitance retention after 1000 charge-discharge cycles. The excellent performance of the composite is due to the synergistic combination of graphene which provides good electrical conductivity and mechanical stability, and PANI nanofiber which provides good redox activity that consequently contributed such high energy density.

  11. Fabrication of NiO thin film electrode for supercapacitor applications

    SciTech Connect

    Mali, V. V.; Navale, S. T.; Chougule, M. A.; Khuspe, G. D.; Godse, P. R.; Patil, V. B.; Pawar, S. A.

    2014-04-24

    Nanocrystalline NiO electrode is successfully electrosynthesized for supercapacitor application. The nanocrystalline NiO electrode is characterized using scanning electron microscope (SEM). Nickel oxide is a highly porous and the film surface looked smooth and composed of fine elongated particles. The supercapacitive performance of NiO electrode is tested using cyclic voltammetry (C-V) technique in 0.5M Na{sub 2}S{sub 2}O{sub 3} electrolyte within potential range of −1.2 to +1.2 V. The effect of scan rate on the capacitance of NiO electrode is studied. The highest specific capacitance of 439 Fg{sup −1} at the voltage scan rate of 50mVs{sup −1} is achieved. Additionally stability and charging–discharging of NiO electrode are studied.

  12. Wearable energy-dense and power-dense supercapacitor yarns enabled by scalable graphene-metallic textile composite electrodes

    NASA Astrophysics Data System (ADS)

    Liu, Libin; Yu, You; Yan, Casey; Li, Kan; Zheng, Zijian

    2015-06-01

    One-dimensional flexible supercapacitor yarns are of considerable interest for future wearable electronics. The bottleneck in this field is how to develop devices of high energy and power density, by using economically viable materials and scalable fabrication technologies. Here we report a hierarchical graphene-metallic textile composite electrode concept to address this challenge. The hierarchical composite electrodes consist of low-cost graphene sheets immobilized on the surface of Ni-coated cotton yarns, which are fabricated by highly scalable electroless deposition of Ni and electrochemical deposition of graphene on commercial cotton yarns. Remarkably, the volumetric energy density and power density of the all solid-state supercapacitor yarn made of one pair of these composite electrodes are 6.1 mWh cm-3 and 1,400 mW cm-3, respectively. In addition, this SC yarn is lightweight, highly flexible, strong, durable in life cycle and bending fatigue tests, and integratable into various wearable electronic devices.

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

    NASA Astrophysics Data System (ADS)

    Cao, Zeyuan

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

  14. Three-Dimensional BC/PEDOT Composite Nanofibers with High Performance for Electrode-Cell Interface.

    PubMed

    Chen, Chuntao; Zhang, Ting; Zhang, Qi; Feng, Zhangqi; Zhu, Chunlin; Yu, Yalin; Li, Kangming; Zhao, Mengyao; Yang, Jiazhi; Liu, Jian; Sun, Dongping

    2015-12-30

    There is an increasing need to synthesize biocompatible nanofibers with excellent mechanical and electrical performance for electrochemical and biomedical applications. Here we report a facile approach to prepare electroactive and flexible 3D nanostructured biomaterials with high performance based on bacterial cellulose (BC) nanofibers. Our approach can coat BC nanofibers with poly(3,4-ethylenedioxythiophene) (PEDOT) by in situ interfacial polymerization in a controllable manner. The PEDOT coating thickness is adjustable by the monomer concentration or reaction time during polymerization, producing nanofibers with a total diameter ranging from 30 to 200 nm. This fabrication process also provides a convenient method to tune different parameters such as the average pore size and electrical conductivity on the demands of actual applications. Our experiments have demonstrated that the 3D BC/PEDOT nanofibers exhibit high specific surface area, excellent mechanical properties, electroactive stability, and low cell cytotoxicity. With electrical stimulation, calcium imaging of PC12 neural cells on BC/PEDOT nanofibers has revealed a significant increase in the percentage of cells with higher action potentials, suggesting an enhanced capacitance effect of charge injection. As an attractive solution to the challenge of designing better electrode-cell interfaces, 3D BC/PEDOT nanofibers promise many important applications such as biosensing devices, smart drug delivery systems, and implantable electrodes for tissue engineering. PMID:26550840

  15. Application of electrochemically reduced graphene oxide on screen-printed ion-selective electrode.

    PubMed

    Ping, Jianfeng; Wang, Yixian; Ying, Yibin; Wu, Jian

    2012-04-01

    In this study, a novel disposable all-solid-state ion-selective electrode using graphene as the ion-to-electron transducer was developed. The graphene film was prepared on screen-printed electrode directly from the graphene oxide dispersion by a one-step electrodeposition technique. Cyclic voltammetry and electrochemical impedance spectroscopy were employed to demonstrate the large double layer capacitance and fast charge transfer of the graphene film modified electrode. On the basis of these excellent properties, an all-solid-state calcium ion-selective electrode as the model was constructed using the calcium ion-selective membrane and graphene film modified electrode. The mechanism about the graphene promoting the ion-to-electron transformation was investigated in detail. The disposable electrode exhibited a Nernstian slope (29.1 mV/decade), low detection limit (10(-5.8) M), and fast response time (less than 10 s). With the high hydrophobic character of graphene materials, no water film was formed between the ion-selective membrane and the underlying graphene layer. Further studies revealed that the developed electrode was insensitive to light, oxygen, and redox species. The use of the disposable electrode for real sample analysis obtained satisfactory results, which made it a promising alternative in routine sensing applications. PMID:22380625

  16. Flexible carbon nanotube-based composite plates as efficient monolithic counter electrodes for dye solar cells.

    PubMed

    Malara, Francesco; Manca, Michele; De Marco, Luisa; Pareo, Paola; Gigli, Giuseppe

    2011-09-01

    We demonstrate a general approach to fabricate a novel low-cost, lightweight and flexible nanocomposite foil that can be effectively implemented as a monolithic counter-electrode in dye solar cells. The pivotal aim of this work was to replace not only the platinum catalyzer film, but even the underlying transparent conductive oxide-coated substrate, by means of a monolithic counter electrode based on carbonaceous materials. According to our approach, a proper dispersion of multiwalled carbon nanotubes (MWCNTs) has been added to a dilute polypropylene solution in toluene. The composite solution has been then adequately mixed and subsequently dried by means of a controlled solvent evaporation process; the resulting powder has been modeled by compression molding into thin plates. Four different series of plates have been realized by tuning the carbon nanotubes concentration from 5 wt % to 20 wt %. Finally, a specifically setup reactive ion etching treatment with oxygen plasma has been carried out onto the plate surface to remove the residual polymeric capping layer and allow the embedded CNTs to protrude on top of the surface. A fine-tuning of the morphological features has been made possible by adjusting the plasma etching conditions. For all the treated surfaces, the most meaningful electrochemical parameters have been quantitatively analyzed by means of both electrochemical impedance spectroscopy and cyclic voltammetry measurements. An as high as 13.8 mA/cm(2) photocurrent density, along with a solar conversion efficiency of 6.67%, has been measured for a dye solar cell mounting a counter-electrode based on a 20 wt % CNT nanocomposite. PMID:21870845

  17. resterilizable electrode for electrosurgery

    NASA Technical Reports Server (NTRS)

    Engstrom, E. R.; Houge, J. C.

    1979-01-01

    Required properties of flexibility, electrical conductivity, tensile strength, and tear resistance of electrosurgical electrodes is retained through utilization of flexible-polymer/conductive particle composites for electrodes.

  18. High reliability nanosandwiched Pt/Ti multilayer electrode actuators for on-chip biomedical applications.

    PubMed

    Tng, Danny Jian Hang; Song, Peiyi; Hu, Rui; Yang, Chengbin; Yong, Ken-Tye

    2014-01-21

    Microactuators provide the main driving force for fluid pumping in microfluidic devices and thus play an important role in on-chip biomedical applications. Interdigitated electrode based electrochemical actuators have provided a viable choice for effective actuation with advantages of flexible controllability, biocompatibility and ease of fabrication. However, the current feature size of a typical electrode structure is around 100 μm, which is relatively large for device miniaturization and integration. Further decrease in the feature size will lead to dramatic decrease in the reliability and lifetime of the actuators, caused by metal delamination. In this work, we propose a novel design of electrodes to fabricate a new type of microactuator with high reliability. To prevent the occurrence of delamination, a nanosandwiched multilayer structure of titanium/platinum is used to construct the conductive metal layer for the interdigitated electrodes. The feature size of the electrodes is greatly reduced to 20 μm where we have reduced the size by 80% of the similar structures reported previously. At the same time, the lifetime of the new electrodes has been dramatically increased to over 400% as compared to the conventional design. With these remarkable improvements in the electrode design, we have fabricated a prototype microfluidic device integrating the new microactuator for drug tests in cancer therapy, demonstrating its usefulness for on-chip biomedical applications. PMID:24270590

  19. Investigation of copper electrodes for mercuric iodide detector applications

    NASA Astrophysics Data System (ADS)

    Bao, X. J.; Schlesinger, T. E.; James, R. B.; Stulen, R. H.; Ortale, C.; van den Berg, L.

    1990-06-01

    Copper diffusion in mercuric iodide was studied by low-temperature photoluminescence (PL) spectroscopy and Auger electron spectroscopy. A broad radiative emission band at a wavelength of about 6720 Å in the PL spectra was found to be related to Cu incorporation in the crystal. PL spectra obtained from surface doping experiments indicate that Cu is a rapid diffuser in HgI2 bulk material. Auger electron spectroscopy performed as a function of depth from the crystal surface confirms the rapid bulk diffusion process of Cu in HgI2. Fabrication of HgI2 nuclear detectors with Cu electrodes indicates that Cu is not acceptable as an electrode material, which is consistent with the fact that it diffuses easily into the bulk crystal and introduces new radiative recombination centers.

  20. Composite materials for space applications

    NASA Technical Reports Server (NTRS)

    Rawal, Suraj P.; Misra, Mohan S.; Wendt, Robert G.

    1990-01-01

    The objectives of the program were to: generate mechanical, thermal, and physical property test data for as-fabricated advanced materials; design and fabricate an accelerated thermal cycling chamber; and determine the effect of thermal cycling on thermomechanical properties and dimensional stability of composites. In the current program, extensive mechanical and thermophysical property tests of various organic matrix, metal matrix, glass matrix, and carbon-carbon composites were conducted, and a reliable database was constructed for spacecraft material selection. Material property results for the majority of the as-fabricated composites were consistent with the predicted values, providing a measure of consolidation integrity attained during fabrication. To determine the effect of thermal cycling on mechanical properties, microcracking, and thermal expansion behavior, approximately 500 composite specimens were exposed to 10,000 cycles between -150 and +150 F. These specimens were placed in a large (18 cu ft work space) thermal cycling chamber that was specially designed and fabricated to simulate one year low earth orbital (LEO) thermal cycling in 20 days. With this rate of thermal cycling, this is the largest thermal cycling unit in the country. Material property measurements of the thermal cycled organic matrix composite laminate specimens exhibited less than 24 percent decrease in strength, whereas, the remaining materials exhibited less than 8 percent decrease in strength. The thermal expansion response of each of the thermal cycled specimens revealed significant reduction in hysteresis and residual strain, and the average CTE values were close to the predicted values.

  1. Application of Electrode Methods in Studies of Nitric Oxide Metabolism and Diffusion Kinetics

    PubMed Central

    Liu, Xiaoping; Zweier, Jay L.

    2012-01-01

    Nitric oxide (NO) has many important physiological roles in the body. Since NO electrodes can directly measure NO concentration in the nM range and in real time, NO electrode methods have been generally used in laboratories for measuring NO concentration in vivo and in vitro. This review focuses on the application of electrode methods in studies of NO diffusion and metabolic kinetics. We have described the physical and chemical properties that need to be considered in the preparation of NO stock solution, discussed the effect of several interfering factors on the measured curves of NO concentration that need to be eliminated in the experimental setup for NO measurements, and provided an overview of the application of NO electrode methods in measuring NO diffusion and metabolic kinetics in solution and in biological systems. This overview covers NO metabolism by oxygen (O2), superoxide, heme proteins, cells and tissues. Important conclusions and physiological implication of these studies are discussed. PMID:23730264

  2. Preparation and Application of Electrodes in Capacitive Deionization (CDI): a State-of-Art Review.

    PubMed

    Jia, Baoping; Zhang, Wei

    2016-12-01

    As a promising desalination technology, capacitive deionization (CDI) have shown practicality and cost-effectiveness in brackish water treatment. Developing more efficient electrode materials is the key to improving salt removal performance. This work reviewed current progress on electrode fabrication in application of CDI. Fundamental principal (e.g. EDL theory and adsorption isotherms) and process factors (e.g. pore distribution, potential, salt type and concentration) of CDI performance were presented first. It was then followed by in-depth discussion and comparison on properties and fabrication technique of different electrodes, including carbon aerogel, activated carbon, carbon nanotubes, graphene and ordered mesoporous carbon. Finally, polyaniline as conductive polymer and its potential application as CDI electrode-enhancing materials were also discussed. PMID:26842797

  3. Preparation and Application of Electrodes in Capacitive Deionization (CDI): a State-of-Art Review

    NASA Astrophysics Data System (ADS)

    Jia, Baoping; Zhang, Wei

    2016-02-01

    As a promising desalination technology, capacitive deionization (CDI) have shown practicality and cost-effectiveness in brackish water treatment. Developing more efficient electrode materials is the key to improving salt removal performance. This work reviewed current progress on electrode fabrication in application of CDI. Fundamental principal (e.g. EDL theory and adsorption isotherms) and process factors (e.g. pore distribution, potential, salt type and concentration) of CDI performance were presented first. It was then followed by in-depth discussion and comparison on properties and fabrication technique of different electrodes, including carbon aerogel, activated carbon, carbon nanotubes, graphene and ordered mesoporous carbon. Finally, polyaniline as conductive polymer and its potential application as CDI electrode-enhancing materials were also discussed.

  4. Application of multiwalled carbon nanotubes/ionic liquid modified electrode for amperometric determination of sulfadiazine.

    PubMed

    Hong, Xiaoping; Zhu, Yan; Ma, Jingying

    2012-12-01

    A highly sensitive amperometric sulfadiazine sensor based on coating multiwalled carbon nanotubes (MWCNTs) and N-octyl-pyridinium-hexafluorophosphate (OPPF(6)) ionic liquid composite on a glassy carbon (GC) electrode is described. The MWCNTs/OPPF(6) composite contributed new properties to electrochemical sensors by combining the advantages of both ionic liquids and MWCNTs. Compared with bare GC electrode, the electrocatalytic activity of MWCNTs/OPPF(6) generated a greatly improved electrochemical detection of sulfadiazine including low oxidation potential, high current responses, and good anti-fouling performance. The oxidation peak currents of sulfadiazine obtained on the MWCNTs/OPPF(6) coated GC electrode were proportional to the concentration of sulfadiazine within the range of 3.3-35.4 μM with a detection limit of 0.21 μM. PMID:21953836

  5. Fabrication of micro/nano-composite porous TiO2 electrodes for quantum dot-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Song, Xiaohui; Wang, Minqiang; Xing, Tiying; Deng, Jianping; Ding, Jijun; Yang, Zhi; Zhang, Xiangyu

    2014-05-01

    For colloidal quantum dots-sensitized solar cells (QDSSC), the penetration and distribution of quantum dots (QDs) within electrodes is very crucial for performance improvement. In view of much bigger size of colloidal QDs than that of dye molecules, a TiO2 electrode with open structure is helpful for the distribution of QDs. In this study, micro/nano-composite porous TiO2 electrodes are fabricated by incorporating polystyrene (PS) spheres into the TiO2 screen-printing paste. After sintering, the embedded PS spheres are burnt off, leaving randomly distributed submicrometer voids in the electrodes, which favor easy penetration of the colloidal CdSe QDs within the TiO2 electrodes, and thus avoiding the unfavorable clogging of pores by CdSe QDs. In addition, this kind of composite structure enhances the scattering properties of the electrodes and hence the light capture inside the device. In order to obtain optimized devices, we probe into the influence of the PS concentration on the photovoltaic performance. The result shows that a maximum conversion efficiency of 2.23% is obtained for the QDSSC made from the PS:TiO2 = 1:4 paste.

  6. Application of composite insulators to transmission lines

    SciTech Connect

    Cherney, E.A.; Brown, R.L.; Karady, G.; Nicholls, J.L.; Orbeck, T.; Pargamin, L.

    1983-05-01

    The paper provides guidelines for the application of composite insulators to transmission lines. These guidelines are based on utility field experiences, results of research laboratory tests and manufacturers' recommendations. Discussed are interchangeability with porcelain and glass insulators, application in contaminated environments, material ageing, insulator icing, the use of grease, resistance to vandalism, temperature extremes, and the need for grading rings. Clarification is provided on the mechanical rating of composite insulators because there is not yet general agreement by various industry groups.

  7. Analysis of a theoretical model for anisotropic enzyme membranes application to enzyme electrodes.

    PubMed

    Pedersen, H; Chotani, G K

    1981-12-01

    A theoretical model of diffusion and reaction in an anisotropic enzyme membrane is presented with particular emphasis on the application of such membranes in enzyme electrodes. The dynamic response of systems in which the kinetics are linear, which comprises the practical operating regime for enzyme electrodes in analysis, is investigated via an analytic solution of the governing differential equations. The response is presented as a function of a single dimensionless group, Μ, that is the membrane modulus. PMID:24233978

  8. Widely applicable coinage metal window electrodes on flexible polyester substrates applied to organic photovoltaics.

    PubMed

    Stec, Helena M; Hatton, Ross A

    2012-11-01

    The fabrication, exceptional properties, and application of 8 nm thick Cu, Ag, Au, and Cu/Ag bilayer electrodes on flexible polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) substrates is reported. These electrodes are fabricated using a solvent free process in which the plastic surface is chemically modified with a molecular monolayer of thiol and amine terminated alkylsilanes prior to metal deposition. The resulting electrodes have a sheet resistance of ≤14 Ω sq⁻¹, are exceptionally robust and can be rapidly thermally annealed at 200 °C to reduce their sheet resistance to ≤9 Ω sq⁻¹. Notably, annealing Au electrodes briefly at 200 °C causes the surface to revert almost entirely to the {111} face, rendering it ideal as a model electrode for fundamental science and practical application alike. The power conversion efficiency of 1 cm² organic photovoltaics (OPVs) employing 8 nm Ag and Au films as the hole-extracting window electrode exhibit performance comparable to those on indium-tin oxide, with the advantage that they are resistant to repeated bending through a small radius of curvature and are chemically well-defined. OPVs employing Cu and bilayer Cu:Ag electrodes exhibit inferior performance due to a lower open-circuit voltage and fill factor. Measurements of the interfacial energetics made using the Kelvin probe technique provide insight into the physical reason for this difference. The results show how coinage metal electrodes offer a viable alternative to ITO on flexible substrates for OPVs and highlight the challenges associated with the use of Cu as an electrode material in this context. PMID:23127805

  9. RuO2/Activated Carbon Composite Electrode Prepared by Modified Colloidal Procedure and Thermal Decomposition Method

    NASA Astrophysics Data System (ADS)

    Li, Xiang; Zheng, Feng; Gan, Weiping; Luo, Xun

    2016-01-01

    RuO2/activated carbon (AC) composite electrode was prepared by a modified colloidal procedure and a thermal decomposition method. The precursor for RuO2/AC was coated on tantalum sheet and annealed at 150°C to 190°C for 3 h to develop thin-film electrode. The microstructure and morphology of the RuO2/AC film were characterized by thermogravimetric analysis (TGA), x-ray diffraction (XRD) analysis, and scanning electron microscopy (SEM). The TGA results showed the maximum loss of RuO2/AC composite film at 410°C, with residual RuO2 of 23.17 wt.%. The amorphous phase structure of the composite was verified by XRD analysis. SEM analysis revealed that fine RuO2 particles were dispersed in an activated carbon matrix after annealing. The electrochemical properties of RuO2/AC electrode were examined by cycling voltammetry, galvanostatic charge-discharge, and cyclic behavior measurements. The specific capacitance of RuO2/AC electrode reached 245 F g-1. The cyclic behavior of RuO2/AC electrode was stable. Optimal annealing was achieved at 170°C for 3 h.

  10. Optimum electrode configuration selection for electrical resistance change based damage detection in composites using an effective independence measure

    NASA Astrophysics Data System (ADS)

    Escalona, Luis; Díaz-Montiel, Paulina; Venkataraman, Satchi

    2016-04-01

    Laminated carbon fiber reinforced polymer (CFRP) composite materials are increasingly used in aerospace structures due to their superior mechanical properties and reduced weight. Assessing the health and integrity of these structures requires non-destructive evaluation (NDE) techniques to detect and measure interlaminar delamination and intralaminar matrix cracking damage. The electrical resistance change (ERC) based NDE technique uses the inherent changes in conductive properties of the composite to characterize internal damage. Several works that have explored the ERC technique have been limited to thin cross-ply laminates with simple linear or circular electrode arrangements. This paper investigates a method of optimum selection of electrode configurations for delamination detection in thick cross-ply laminates using ERC. Inverse identification of damage requires numerical optimization of the measured response with a model predicted response. Here, the electrical voltage field in the CFRP composite laminate is calculated using finite element analysis (FEA) models for different specified delamination size and locations, and location of ground and current electrodes. Reducing the number of sensor locations and measurements is needed to reduce hardware requirements, and computational effort needed for inverse identification. This paper explores the use of effective independence (EI) measure originally proposed for sensor location optimization in experimental vibration modal analysis. The EI measure is used for selecting the minimum set of resistance measurements among all possible combinations of selecting a pair of electrodes among the n electrodes. To enable use of EI to ERC required, it is proposed in this research a singular value decomposition SVD to obtain a spectral representation of the resistance measurements in the laminate. The effectiveness of EI measure in eliminating redundant electrode pairs is demonstrated by performing inverse identification of

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

    PubMed

    Gayen, Pralay; Chaplin, Brian P

    2016-01-27

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

  12. All-solid-state electrochemical capacitors using MnO2 electrode/SiO2-Nafion electrolyte composite prepared by the sol-gel process

    NASA Astrophysics Data System (ADS)

    Shimamoto, Kazushi; Tadanaga, Kiyoharu; Tatsumisago, Masahiro

    2014-02-01

    Electrode-electrolyte composites of MnO2 active material, acetylene black (AB), and SiO2-Nafion solid electrolyte were prepared using the sol-gel process to form good solid-solid interfaces. The composites were obtained by the addition of MnO2 and AB into a sol of hydrolyzed tetraethoxysilane with Nafion, and successive solidification of the precursor sol. Scanning electron microscope and energy dispersive X-ray spectroscopy measurements show that good solid-solid interface is formed between electrodes and solid electrolytes in the composites. All-solid-state hybrid capacitors were fabricated using the composites or the hand-grinding mixture of MnO2, AB and SiO2-Nafion powder as positive electrodes, activated carbon powder as a negative electrode, and phosphosilicate gel as a solid electrolyte. The all-solid-state hybrid capacitors using the composites exhibit larger capacitances and better rate performance than the capacitors using the electrode prepared by hand-mixing of powders. Specific discharge capacitances of the capacitor with the composite are 85 F g-1 for the one with the composite electrode and 48 F g-1 for the one with the hand-mixed electrode, at 1 mA cm-2. Moreover, the all-solid-state capacitors using the composite electrode can be operated at temperatures between -30 °C and 60 °C.

  13. VISCOSITY AND BINDER COMPOSITION EFFECTS ON TYROSINASE-BASED CARBON PASTE ELECTRODE FOR DETECTION OF PHENOL AND CATECHOL

    EPA Science Inventory

    The systematic study of the effect of binder viscosity on the sensitivity of a tyrosinase-based carbon paste electrode (CPE) biosensor for phenol and catechol is reported. Silicon oil binders with similar (polydimethylsiloxane) chemical composition were used to represent a wid...

  14. Bioanalysis with Potentiometric Membrane Electrodes.

    ERIC Educational Resources Information Center

    Rechnitz, G. A.

    1982-01-01

    Discusses major themes and interrelationships common to bioselective potentiometric membrane electrodes including the nature of bioselective electrodes, applications, and future prospects. Includes tables on traditional ion-selective membrane electrodes, nontraditional electrodes, and typical biocatalytic potentiometric electrodes. (Author/JN)

  15. Novel electrode-elastomer combinations for improved performance and application of dielectric elastomers

    NASA Astrophysics Data System (ADS)

    Yuan, Wei

    Dielectric elastomers are the most promising technology for mimicking human muscles in terms of strain, stress, and work density, etc. Actuators have been fabricated based on different design concepts and configurations for applications in robotics, prosthetic devices, medical implants, pumps, and valves. However, to date these actuators have experienced high rates of failure caused by electrical shorting of the compliant electrodes through the elastomer film during electrical breakdown, which has prevented their practical application. In this thesis, single walled carbon nanotube (SWNT) thin films were employed as compliant electrodes for dielectric elastomers to reduce the rate of failure. Thanks to the high aspect ratio of the SWNTs, the electrodes maintain substantial conductance at high biaxial strains. 3M VHB acrylics can be actuated up to 200% area strain with SWNT electrodes, this matches the performance of actuators with carbon grease electrodes. During uni-directional stretching, SWNT electrodes can maintain surface conductivity up to 700% linear strain. SWNT electrodes can experience a self-clearing process under high voltage discharging and electrically isolate the electrodes around the breakdown sites when breakdown events happen. With conventional dielectric elastomer electrode materials such as carbon grease and carbon black, a single breakdown event results in a permanent loss in the actuator's functionality. In contrast, for SWNT electrodes, the SWNTs around the breakdown site will be degraded and become non-conductive. The non-conductive area expands outward until the high voltage discharging stops. As such, the opposing electrodes are prevented from coming into contact with each other and forming an electrical short and the breakdown site is electrically isolated from the remainder of the active area. Despite the existence of the breakdown sites, the dielectric elastomer will resume its functionality and avoid permanent failure. Thus, dielectric

  16. Selective growth of ZnO nanorods on microgap electrodes and their applications in UV sensors

    PubMed Central

    2014-01-01

    Selective area growth of ZnO nanorods is accomplished on microgap electrodes (spacing of 6 μm) by using a facile wet chemical etching process. The growth of ZnO nanorods on a selected area of microgap electrode is carried out by hydrothermal synthesis forming nanorod bridge between two electrodes. This is an attractive, genuine, direct, and highly reproducible technique to grow nanowire/nanorod onto the electrodes on selected area. The ZnO nanorods were grown at 90°C on the pre-patterned electrode system without destroying the electrode surface structure interface and geometry. The ZnO nanorods were tested for their application in ultraviolet (UV) sensors. The photocurrent-to-dark (Iph/Id) ratio was 3.11. At an applied voltage of 5 V, the response and recovery time was 72 and 110 s, respectively, and the response reached 2 A/W. The deposited ZnO nanorods exhibited a UV photoresponse that is promising for future cost-effective and low-power electronic UV-sensing applications. PMID:24423232

  17. Microcavity-Free Broadband Light Outcoupling Enhancement in Flexible Organic Light-Emitting Diodes with Nanostructured Transparent Metal-Dielectric Composite Electrodes.

    PubMed

    Xu, Lu-Hai; Ou, Qing-Dong; Li, Yan-Qing; Zhang, Yi-Bo; Zhao, Xin-Dong; Xiang, Heng-Yang; Chen, Jing-De; Zhou, Lei; Lee, Shuit-Tong; Tang, Jian-Xin

    2016-01-26

    Flexible organic light-emitting diodes (OLEDs) hold great promise for future bendable display and curved lighting applications. One key challenge of high-performance flexible OLEDs is to develop new flexible transparent conductive electrodes with superior mechanical, electrical, and optical properties. Herein, an effective nanostructured metal/dielectric composite electrode on a plastic substrate is reported by combining a quasi-random outcoupling structure for broadband and angle-independent light outcoupling of white emission with an ultrathin metal alloy film for optimum optical transparency, electrical conduction, and mechanical flexibility. The microcavity effect and surface plasmonic loss can be remarkably reduced in white flexible OLEDs, resulting in a substantial increase in the external quantum efficiency and power efficiency to 47.2% and 112.4 lm W(-1). PMID:26687488

  18. Bristle-sensors—low-cost flexible passive dry EEG electrodes for neurofeedback and BCI applications

    NASA Astrophysics Data System (ADS)

    Grozea, Cristian; Voinescu, Catalin D.; Fazli, Siamac

    2011-04-01

    In this paper, we present a new, low-cost dry electrode for EEG that is made of flexible metal-coated polymer bristles. We examine various standard EEG paradigms, such as capturing occipital alpha rhythms, testing for event-related potentials in an auditory oddball paradigm and performing a sensory motor rhythm-based event-related (de-) synchronization paradigm to validate the performance of the novel electrodes in terms of signal quality. Our findings suggest that the dry electrodes that we developed result in high-quality EEG recordings and are thus suitable for a wide range of EEG studies and BCI applications. Furthermore, due to the flexibility of the novel electrodes, greater comfort is achieved in some subjects, this being essential for long-term use.

  19. ZnO:H indium-free transparent conductive electrodes for active-matrix display applications

    SciTech Connect

    Chen, Shuming Wang, Sisi

    2014-12-01

    Transparent conductive electrodes based on hydrogen (H)-doped zinc oxide (ZnO) have been proposed for active-matrix (AM) display applications. When fabricated with optimal H plasma power and optimal plasma treatment time, the resulting ZnO:H films exhibit low sheet resistance of 200 Ω/◻ and high average transmission of 85% at a film thickness of 150 nm. The demonstrated transparent conductive ZnO:H films can potentially replace indium-tin-oxide and serve as pixel electrodes for organic light-emitting diodes as well as source/drain electrodes for ZnO-based thin-film transistors. Use of the proposed ZnO:H electrodes means that two photomask stages can be removed from the fabrication process flow for ZnO-based AM backplanes.

  20. ZnO:H indium-free transparent conductive electrodes for active-matrix display applications

    NASA Astrophysics Data System (ADS)

    Chen, Shuming; Wang, Sisi

    2014-12-01

    Transparent conductive electrodes based on hydrogen (H)-doped zinc oxide (ZnO) have been proposed for active-matrix (AM) display applications. When fabricated with optimal H plasma power and optimal plasma treatment time, the resulting ZnO:H films exhibit low sheet resistance of 200 Ω/◻ and high average transmission of 85% at a film thickness of 150 nm. The demonstrated transparent conductive ZnO:H films can potentially replace indium-tin-oxide and serve as pixel electrodes for organic light-emitting diodes as well as source/drain electrodes for ZnO-based thin-film transistors. Use of the proposed ZnO:H electrodes means that two photomask stages can be removed from the fabrication process flow for ZnO-based AM backplanes.

  1. Bristle-sensors--low-cost flexible passive dry EEG electrodes for neurofeedback and BCI applications.

    PubMed

    Grozea, Cristian; Voinescu, Catalin D; Fazli, Siamac

    2011-04-01

    In this paper, we present a new, low-cost dry electrode for EEG that is made of flexible metal-coated polymer bristles. We examine various standard EEG paradigms, such as capturing occipital alpha rhythms, testing for event-related potentials in an auditory oddball paradigm and performing a sensory motor rhythm-based event-related (de-) synchronization paradigm to validate the performance of the novel electrodes in terms of signal quality. Our findings suggest that the dry electrodes that we developed result in high-quality EEG recordings and are thus suitable for a wide range of EEG studies and BCI applications. Furthermore, due to the flexibility of the novel electrodes, greater comfort is achieved in some subjects, this being essential for long-term use. PMID:21436526

  2. Development of Amperometric Biosensors Based on Nanostructured Tyrosinase-Conducting Polymer Composite Electrodes

    PubMed Central

    Lupu, Stelian; Lete, Cecilia; Balaure, Paul Cătălin; Caval, Dan Ion; Mihailciuc, Constantin; Lakard, Boris; Hihn, Jean-Yves; del Campo, Francisco Javier

    2013-01-01

    Bio-composite coatings consisting of poly(3,4-ethylenedioxythiophene) (PEDOT) and tyrosinase (Ty) were successfully electrodeposited on conventional size gold (Au) disk electrodes and microelectrode arrays using sinusoidal voltages. Electrochemical polymerization of the corresponding monomer was carried out in the presence of various Ty amounts in aqueous buffered solutions. The bio-composite coatings prepared using sinusoidal voltages and potentiostatic electrodeposition methods were compared in terms of morphology, electrochemical properties, and biocatalytic activity towards various analytes. The amperometric biosensors were tested in dopamine (DA) and catechol (CT) electroanalysis in aqueous buffered solutions. The analytical performance of the developed biosensors was investigated in terms of linear response range, detection limit, sensitivity, and repeatability. A semi-quantitative multi-analyte procedure for simultaneous determination of DA and CT was developed. The amperometric biosensor prepared using sinusoidal voltages showed much better analytical performance. The Au disk biosensor obtained by 50 mV alternating voltage amplitude displayed a linear response for DA concentrations ranging from 10 to 300 μM, with a detection limit of 4.18 μM. PMID:23698270

  3. Composite Development and Applications for RLV Tankage

    NASA Technical Reports Server (NTRS)

    Wright, Richard J.; Achary, David C.; McBain, Michael C.

    2003-01-01

    The development of polymer composite cryogenic tanks is a critical step in creating the next generation of launch vehicles. Future launch vehicles need to minimize the gross liftoff weight (GLOW), which is possible due to the 28%-41% reduction in weight that composite materials can provide over current aluminum technology. The development of composite cryogenic tanks, feedlines, and unpressurized structures are key enabling technologies for performance and cost enhancements for Reusable Launch Vehicles (RLVs). The technology development of composite tanks has provided direct and applicable data for feedlines, unpressurized structures, material compatibility, and cryogenic fluid containment for highly loaded complex structures and interfaces. All three types of structure have similar material systems, processing parameters, scaling issues, analysis methodologies, NDE development, damage tolerance, and repair scenarios. Composite cryogenic tankage is the most complex of the 3 areas and provides the largest breakthrough in technology. A building block approach has been employed to bring this family of difficult technologies to maturity. This approach has built up composite materials, processes, design, analysis and test methods technology through a series of composite test programs beginning with the NASP program to meet aggressive performance goals for reusable launch vehicles. In this paper, the development and application of advanced composites for RLV use is described.

  4. Effect of poly(3,4-ethylenedioxythiophene) (PEDOT) in carbon-based composite electrodes for electrochemical supercapacitors

    NASA Astrophysics Data System (ADS)

    Lei, Chunhong; Wilson, Peter; Lekakou, Constantina

    Electrochemical double layer supercapacitor cells were fabricated and tested using composite electrodes of activated carbon with carbon black and poly(3,4-ethylenedioxythiophene) (PEDOT), and an organic electrolyte 1 M TEABF 4/PC solution. The effect of PEDOT on the performance of the EDLC cells was explored and the cells were characterised by electrochemical impedance spectroscopy (EIS), cyclic voltammetry and galvanostatic charge-discharge. A generalised equivalent circuit model was developed for which numerical simulations were performed to determine the properties and parameters of its components from the EIS data. It was found that the proposed model fitted successfully the data of all tested cells. PEDOT enhanced the electrode and cell capacitance via its pseudo-capacitance effect up to a maximum value for an optimum PEDOT loading and greatly increased the energy density of the cell while the maximum power density has been still maintained at supercapacitor levels. Furthermore, PEDOT replaced PVDF as a binder and harmful solvent release was reduced during electrode processing. Activated carbon-carbon black composite electrodes with PEDOT as binder were found to have specific capacitance superior to that of activated carbon-carbon black electrodes with PVDF binder.

  5. Composite material application for liquid rocket engines

    NASA Technical Reports Server (NTRS)

    Heubner, S. W.

    1982-01-01

    With increasing emphasis on improving engine thrust-to-weight ratios to provide improved payload capabilities, weight reductions achievable by the use of composites have become attractive. Of primary significance is the weight reduction offered by composites, although high temperature properties and cost reduction were also considered. The potential for application of composites to components of Earth-to-orbit hydrocarbon engines and orbit-to-orbit LOX/H2 engines was assessed. The components most likely to benefit from the application of composites were identified, as were the critical technology areas where developed would be required. Recommendations were made and a program outlined for the design, fabrication, and demonstration of specific engine components.

  6. Automotive applications for advanced composite materials

    NASA Technical Reports Server (NTRS)

    Deutsch, G. C.

    1978-01-01

    A description is presented of nonaerospace applications for advanced composite materials with special emphasis on the automotive applications. The automotive industry has to satisfy exacting requirements to reduce the average fuel consumption of cars. A feasible approach to accomplish this involves the development of composites cars with a total weight of 2400 pounds and a fuel consumption of 33 miles per gallon. In connection with this possibility, the automotive companies have started to look seriously at composite materials. The aerospace industry has over the past decade accumulated a considerable data base on composite materials and this is being made available to the nonaerospace sector. However, the automotive companies will place prime emphasis on low cost resins which lend themselves to rapid fabrication techniques.

  7. New textile composite materials development, production, application

    NASA Technical Reports Server (NTRS)

    Mikhailov, Petr Y.

    1993-01-01

    New textile composite materials development, production, and application are discussed. Topics covered include: super-high-strength, super-high-modulus fibers, filaments, and materials manufactured on their basis; heat-resistant and nonflammable fibers, filaments, and textile fabrics; fibers and textile fabrics based on fluorocarbon poylmers; antifriction textile fabrics based on polyfen filaments; development of new types of textile combines and composite materials; and carbon filament-based fabrics.

  8. Preparation and characterization of nanostructured NiO/MnO{sub 2} composite electrode for electrochemical supercapacitors

    SciTech Connect

    Liu Enhui Li Wen; Li Jian; Meng Xiangyun; Ding Rui; Tan Songting

    2009-05-06

    Nanostructured nickel-manganese oxides composite was prepared by the sol-gel and the chemistry deposition combination new route. The surface morphology and structure of the composite were characterized by scanning electron microscope and X-ray diffraction. The as-synthesized NiO/MnO{sub 2} samples exhibit higher surface area of 130-190 m{sup 2} g{sup -1}. Cyclic voltammetry and galvanostatic charge/discharge measurements were applied to investigate the electrochemical performance of the composite electrodes with different ratios of NiO/MnO{sub 2}. When the mass ratio of MnO{sub 2} and NiO in composite material is 80:20, the specific capacitance value of NiO/MnO{sub 2} calculated from the cyclic voltammetry curves is 453 F g{sup -1}, for pure NiO and MnO{sub 2} are 209, 330 F g{sup -1} in 6 mol L{sup -1} KOH electrolyte and at scan rate of 10 mV s{sup -1}, respectively. The specific capacitance of NiO/MnO{sub 2} electrode is much larger than that of each pristine component. Moreover, the composite electrodes showed high power density and stable electrochemical properties.

  9. The preparation and performance of calcium carbide-derived carbon/polyaniline composite electrode material for supercapacitors

    NASA Astrophysics Data System (ADS)

    Zheng, Liping; Wang, Ying; Wang, Xianyou; Li, Na; An, Hongfang; Chen, Huajie; Guo, Jia

    Calcium carbide (CaC 2)-derived carbon (CCDC)/polyaniline (PANI) composite materials are prepared by in situ chemical oxidation polymerization of an aniline solution containing well-dispersed CCDC. The structure and morphology of CCDC/PANI composite are characterized by Fourier infrared spectroscopy (FTIR), scanning electron microscope (SEM), transmission electron microscopy (TEM) and N 2 sorption isotherms. It has been found that PANI was uniformly deposited on the surface and the inner pores of CCDC. The supercapacitive behaviors of the CCDC/PANI composite materials are investigated with cyclic voltammetry (CV), galvanostatic charge/discharge and cycle life measurements. The results show that the CCDC/PANI composite electrodes have higher specific capacitances than the as grown CCDC electrodes and higher stability than the conducting polymers. The capacitance of CCDC/PANI composite electrode is as high as 713.4 F g -1 measured by cyclic voltammetry at 1 mV s -1. Besides, the capacitance retention of coin supercapacitor remained 80.1% after 1000 cycles.

  10. Preparation and characterization of composite electrodes of coconut-shell-based activated carbon and hydrous ruthenium oxide for supercapacitors

    NASA Astrophysics Data System (ADS)

    Dandekar, Mukta S.; Arabale, Girish; Vijayamohanan, K.

    The relationship between the structure-specific capacitance (F g -1) of a composite electrode consisting of activated coconut-shell carbon and hydrous ruthenium oxide (RuO x(OH) y) has been evaluated by impregnating various amounts of RuO x(OH) y into activated carbon that is specially prepared with optimum pore-size distribution. The composite electrode shows an enhanced specific capacitance of 250 F g -1 in 1 M H 2SO 4 with 9 wt.% ruthenium incorporated. Chemical and structural characterization of the composites reveals a homogeneous distribution of amorphous RuO x(OH) y throughout the porous network of the activated carbon. Electrochemical characterization indicates an almost linear dependence of capacitance on the amount of ruthenium owing to its pseudocapacitive nature.

  11. Bridging Oriented Copper Nanowire-Graphene Composites for Solution-Processable, Annealing-Free, and Air-Stable Flexible Electrodes.

    PubMed

    Zhang, Wang; Yin, Zhenxing; Chun, Alvin; Yoo, Jeeyoung; Kim, Youn Sang; Piao, Yuanzhe

    2016-01-27

    One-dimensional flexible metallic nanowires (NWs) are of considerable interest for next-generation wearable devices. The unavoidable challenge for a wearable electrode is the assurance of high conductivity, flexibility, and durability with economically feasible materials and simple manufacturing processes. Here, we use a straightforward solvothermal method to prepare a flexible conductive material that contains reduced graphene oxide (RGO) nanosheets bridging oriented copper NWs. The GO-assistance route can successfully meet the criteria listed above and help the composite films maintain high conductivity and durable flexibility without any extra treatment, such as annealing or acid processes. The composite film exhibits a high electrical performance (0.808 Ω·sq(-1)) without considerable change over 30 days under ambient conditions. Moreover, the Cu NW-RGO composites can be deposited on polyester cloth as a lightweight wearable electrode with high durability and simple processability and are very promising for a wide variety of electronic devices. PMID:26720592

  12. Composite structural armor for combat vehicle applications

    NASA Technical Reports Server (NTRS)

    Haskell, William E., III; Alesi, A. L.; Parsons, G. R.

    1990-01-01

    Several projects that have demonstrated the advantages of using thick composite armor technology for structural applications in armored combat vehicles are discussed. The first involved composite cargo doors for the Marine Corps LVTP-7 amphibious landing vehicle. Another was a demonstration composite turret that offered a weight reduction of 15.5 percent. The advantages of this composite armor compared to metallic armors used for combat vehicle hull and turret applications are reduced weight at equal ballistic protection; reduced back armor spall; excellent corrosion resistance; reduced production costs by parts consolidation; and inherent thermal and acoustic insulative properties. Based on the encouraging results of these past programs, the Demonstration Composite Hull Program was started in September 1986. To demonstrate this composite armor technology, the Army's newest infantry fighting vehicle, the Bradley Fighting Vehicle (BFV), was selected as a model. A composite infantry fighting vehicle, designated the CIFV for this program, has been designed and fabricated and is currently undergoing a 6000 mile field endurance test. The CIFV demonstration vehicle uses the BFV engine, transmission, suspension, track and other equipment.

  13. Fabrication of highly porous platinum electrodes for micro-scale applications by pulsed electrodeposition and dealloying

    NASA Astrophysics Data System (ADS)

    Köhler, Christian; Kloke, Arne; Drzyzga, Anna; Zengerle, Roland; Kerzenmacher, Sven

    2013-11-01

    We present the implementation and optimization of a novel electrodeposition method for the fabrication of highly porous platinum electrodes. It is based on the co-deposition of platinum and copper and the selective dealloying of copper in a pulsed manner. The new process yields mechanically stable platinum electrodes with roughness factors of up to RF = 6500 ± 700, compared to the state-of-the-art cyclic electrodeposition method this corresponds to an improvement in RF by 111%. Furthermore the time demand for fabrication is reduced by 59%, whereas the platinum utilization is increased by 53%. The method is particularly advantageous for applications such as micro fuel cells since it enables the precise deposition of catalytically active electrodes on micro-structured conductive areas. In this context the novel platinum electrodes show higher current densities for the oxidation of formic acid and glucose than state-of-the-art electrodes. In terms of methanol oxidation their catalytic activity is comparable to commercial direct methanol fuel cell (DMFC) electrodes, fabricated from Pt-Ru nanoparticles dispersed on carbon black.

  14. Long electrodes for radio frequency ablation: comparative study of surface versus intramural application.

    PubMed

    Berjano, Enrique J; Hornero, Fernando; Atienza, Felipe; Montero, Anastasio

    2003-12-01

    There is increasing use of radio frequency (RF) ablation with long electrodes in the intraoperative treatment of atrial fibrillation. Nevertheless, the disparity in the lesion geometry in both depth and width is the major pitfall in the use of RF currents. The objective of this study was to differentiate the shape and size of long lesions created by three surface application electrodes (SAE) and two intramural electrodes (IE). The SAE included a standard multi-polar catheter, and two standard electrosurgical pencils. The IE consisted of a needle and a wire both intramurally buried. The lesions were created on fresh fragments of porcine ventricular tissue. The IE created lesions with a curved prism-like shape around the electrode body, with homogeneous characteristics along the lesion trajectory. On the contrary, the lesions created with the SAE were in the shape of an hourglass. They showed a different geometry between the central zone and the edge zone (p<0.001 for depth and surface width). Electrical impedance evolution was recorded during the RF heating. We observed a slow decrease of the impedance in all the electrodes, except in the wire electrode. In conclusion, the results suggest that the IE might be a more suitable option than SAE when it is necessary to create long and homogeneous thermal lesions. PMID:14630474

  15. Improving sensitivity of photorefractive polymer composites for holographic display applications

    NASA Astrophysics Data System (ADS)

    Christenson, Cory W.

    This work presents recent progress in the area of organic photorefractive polymer composites. These materials have been previously shown to be a suitable medium for dynamic holographic displays, with multiple colors and single frame writing times on the order of seconds. However, these materials still require large electric fields and high intensity lasers to function effectively. Recent advancements in improving these areas are discussed, including a review of the history and state-of-the-art in photorefractive polymer composites. The addition of electron traps via low loading of the electron-transporting molecule Alq3 is shown to dramatically improve the diffraction efficiency and reduce the required field. The grating formation also proceeds faster by more than one order of magnitude, leading to an increase in sensitivity by a factor of 3. The dynamics of these materials also show evidence of competing gratings indicative of bipolar charge transport and trapping. The addition of an amorphous polycarbonate (APC) buffer layer is reported to have a similar effect on the steady-state diffraction efficiency, and the further doping with a fullerene derivative (PCBM) allows a 3x increase in the efficiency in the reflection geometry, which is normally poor due to the small grating spacing. These composites reveal the fundamental limits of the reflection geometry, based on the physics of high frequency gratings. A reversal in the direction and increase in the magnitude of the two-beam coupling energy transfer is also observed. The use of interdigitated coplanar electrodes, instead of the standard uniform electrodes in a parallel-plate geometry, is shown to result in large diffraction efficiency with symmetric writing beams due to the increased projection field. The efficiency is similar to that achieved in the standard samples with large slant angles and much better than those geometries typically used in applications, with the benefit that the writing beams do not have

  16. Enhanced capacitance of composite TiO2 nanotube/boron-doped diamond electrodes studied by impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Siuzdak, K.; Bogdanowicz, R.; Sawczak, M.; Sobaszek, M.

    2014-12-01

    We report on novel composite nanostructures based on boron-doped diamond thin films grown on top of TiO2 nanotubes. The nanostructures made of BDD-modified titania nanotubes showed an increase in activity and performance when used as electrodes in electrochemical environments. The BDD thin films (~200-500 nm) were deposited using microwave plasma assisted chemical vapor deposition (MW PA CVD) onto anodically fabricated TiO2 nanotube arrays. The influence of boron-doping level, methane admixture and growth time on the performance of the Ti/TiO2/BDD electrode was studied in detail. Scanning electron microscopy (SEM) was applied to investigate the surface morphology and grain size distribution. Moreover, the chemical composition of TiO2/BDD electrodes was investigated by means of micro-Raman spectroscopy. The composite electrodes TiO2/BDD are characterized by a significantly higher capacitive current compared to BDD films deposited directly onto a Ti substrate. The novel composite electrode of TiO2 nanotube arrays overgrown by boron-doped diamond (BDD) immersed in 0.1 M NaNO3 can deliver a specific capacitance of 2.10, 4.79, and 7.46 mF cm-2 at a scan rate of 10 mV s-1 for a [B]/[C] ratio of 2k, 5k and 10k, respectively. The substantial improvement of electrochemical performance and the excellent rate capability could be attributed to the synergistic effect of TiO2 treatment in CH4 : H2 plasma and the high electrical conductivity of BDD layers. The analysis of electrochemical impedance spectra using an electric equivalent circuit allowed us to determine the surface area on the basis of the value of constant phase element.

  17. Earth impedance model for through-the-earth communication applications with electrodes

    NASA Astrophysics Data System (ADS)

    Bataller, Vanessa; MuñOz, Antonio; Gaudó, Pilar Molina; Mediano, Arturo; Cuchí, José A.; Villarroel, José L.

    2010-12-01

    Through-the-earth (TTE) communications are relevant in applications such as caving, tunnel and cave rescue, mining, and subsurface radiolocation. The majority of the TTE communication systems use ground electrodes as load antenna. Wires, electrode contact, and earth impedances are the major contributors to the impedance observed by the transmitter. In this paper, state-of-art models found in the literature are reviewed, and an improved method to measure the earth impedance is presented. The paper also proposes an optimal circuit model for earth impedance between electrodes as a function of frequency, as a consequence of the particular conditions of the application. The model is validated with measurements for different soil conditions, showing a good agreement between empirical data and the simulation results.

  18. High-energy-density, all-solid-state microsupercapacitors with three-dimensional interdigital electrodes of carbon/polymer electrolyte composite

    NASA Astrophysics Data System (ADS)

    Pu, Juan; Wang, Xiaohong; Zhang, Tianyi; Li, Siwei; Liu, Jinghe; Komvopoulos, Kyriakos

    2016-01-01

    Novel all-solid-state microsupercapacitors (MSCs) with three-dimensional (3D) electrodes consisting of active materials (i.e., graphene or activated carbon (AC) particles) and polymer electrolyte (PE) designed for high-energy-density storage applications were fabricated and tested in this work. The incorporation of PE in the electrode material enhances the accessibility of electrolyte ions to the surface of active materials and decreases the ion diffusion path during electrochemical charge/discharge. For a scan rate of 5 mV s-1, the MSCs with graphene/PE and AC/PE composite electrodes demonstrate a very high areal capacitance of 95 and 134 mF cm-2, respectively, comparable to that of 3D MSCs with liquid electrolyte. In addition, the graphene/PE MSCs show a ˜70% increase in specific capacitance after 10 000 charge/discharge cycles, attributed to an electro-activation process resulting from ion intercalation between the graphene nanosheets. The AC/PE MSCs also demonstrate excellent stability. The results of this study illustrate the potential of the present 3D MSCs for various high-density solid-state energy storage applications.

  19. Cobalt Sulfide/Graphene Composite Hydrogel as Electrode for High-Performance Pseudocapacitors

    PubMed Central

    Meng, Xiaoqian; Deng, Jin; Zhu, Junwu; Bi, Huiping; Kan, Erjun; Wang, Xin

    2016-01-01

    Graphene and its composite hydrogels with interconnected three-dimensional (3D) structure have raised continuous attention in energy storage. Herein, we describe a simple hydrothermal strategy to synthesize 3D CoS/graphene composite hydrogel (CGH), which contains the reduction of GO sheets and anchoring of CoS nanoparticles on graphene sheets. The formed special 3D structure endows this composite with high electrochemical performance. Remarkably, the obtained 3D CGH exhibits high specific capacitance (Cs) of 564 F g−1 at a current density of 1 A g−1 (about 1.3 times higher than pure CoS), superior rate capability and high stability. It is worth mentioning that this methodology is readily adaptable to decorating CoS nanoparticles onto graphene sheets and may be extended to the preparation of other pseudocapacitive materials based on graphene hydrogels for electrochemical applications. PMID:26880686

  20. Cobalt Sulfide/Graphene Composite Hydrogel as Electrode for High-Performance Pseudocapacitors

    NASA Astrophysics Data System (ADS)

    Meng, Xiaoqian; Deng, Jin; Zhu, Junwu; Bi, Huiping; Kan, Erjun; Wang, Xin

    2016-02-01

    Graphene and its composite hydrogels with interconnected three-dimensional (3D) structure have raised continuous attention in energy storage. Herein, we describe a simple hydrothermal strategy to synthesize 3D CoS/graphene composite hydrogel (CGH), which contains the reduction of GO sheets and anchoring of CoS nanoparticles on graphene sheets. The formed special 3D structure endows this composite with high electrochemical performance. Remarkably, the obtained 3D CGH exhibits high specific capacitance (Cs) of 564 F g-1 at a current density of 1 A g-1 (about 1.3 times higher than pure CoS), superior rate capability and high stability. It is worth mentioning that this methodology is readily adaptable to decorating CoS nanoparticles onto graphene sheets and may be extended to the preparation of other pseudocapacitive materials based on graphene hydrogels for electrochemical applications.

  1. Cobalt Sulfide/Graphene Composite Hydrogel as Electrode for High-Performance Pseudocapacitors.

    PubMed

    Meng, Xiaoqian; Deng, Jin; Zhu, Junwu; Bi, Huiping; Kan, Erjun; Wang, Xin

    2016-01-01

    Graphene and its composite hydrogels with interconnected three-dimensional (3D) structure have raised continuous attention in energy storage. Herein, we describe a simple hydrothermal strategy to synthesize 3D CoS/graphene composite hydrogel (CGH), which contains the reduction of GO sheets and anchoring of CoS nanoparticles on graphene sheets. The formed special 3D structure endows this composite with high electrochemical performance. Remarkably, the obtained 3D CGH exhibits high specific capacitance (Cs) of 564 F g(-1) at a current density of 1 A g(-1) (about 1.3 times higher than pure CoS), superior rate capability and high stability. It is worth mentioning that this methodology is readily adaptable to decorating CoS nanoparticles onto graphene sheets and may be extended to the preparation of other pseudocapacitive materials based on graphene hydrogels for electrochemical applications. PMID:26880686

  2. Supported protein G on gold electrode: characterization and immunosensor application.

    PubMed

    Hafaiedh, Imen; Chammem, Hanen; Abdelghani, Adnane; Ait, Eric; Feldman, Laurent; Meilhac, Olivier; Mora, Laurence

    2013-11-15

    In this work, we study the electrochemical properties of protein layer grafted on gold electrode for C-reactive protein detection. Two CRP-antibody immobilization methods were used: the first method is based on direct physisorption of CRP-antibody onto the gold surface and the second method is based on oriented CRP-antibody with protein G intermediate layer. The two developed immunosensors were tested against CRP antigen in phosphate buffer saline solution and in human plasma. The electrochemical characterization of each immobilized layers was achieved by cyclic voltammetry and impedance spectroscopy. The morphology of the deposited biomolecules was observed by Atomic Force Microscopy and the roughness was measured. Moreover, contact angle measurement was used for wettability studies. The response of the developed immunosensors was reproducible, rapid, and highly stable and a detection limit of 100 fg/mL and 10 pg/mL antigen was observed with and without protein G respectively. The developed immunosensors was used for CRP detection in human plasma. PMID:24148377

  3. Metal Matrix Composite Materials for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Bhat, Biliyar N.; Jones, C. S. (Technical Monitor)

    2001-01-01

    Metal matrix composites (MMC) are attractive materials for aerospace applications because of their high specific strength, high specific stiffness, and lower thermal expansion coefficient. They are affordable since complex parts can be produced by low cost casting process. As a result there are many commercial and Department of Defense applications of MMCs today. This seminar will give an overview of MMCs and their state-of-the-art technology assessment. Topics to be covered are types of MMCs, fabrication methods, product forms, applications, and material selection issues for design and manufacture. Some examples of current and future aerospace applications will also be presented and discussed.

  4. Polydimethylsiloxane-based conducting composites and their applications in microfluidic chip fabrication

    PubMed Central

    Gong, Xiuqing; Wen, Weijia

    2009-01-01

    This paper reviews the design and fabrication of polydimethylsiloxane (PDMS)-based conducting composites and their applications in microfluidic chip fabrication. Owing to their good electrical conductivity and rubberlike elastic characteristics, these composites can be used variously in soft-touch electronic packaging, planar and three-dimensional electronic circuits, and in-chip electrodes. Several microfluidic components fabricated with PDMS-based composites have been introduced, including a microfluidic mixer, a microheater, a micropump, a microdroplet controller, as well as an all-in-one microfluidic chip. PMID:19693388

  5. Silver nanowire composite thin films as transparent electrodes for Cu(In,Ga)Se₂/ZnS thin film solar cells.

    PubMed

    Tan, Xiao-Hui; Chen, Yu; Liu, Ye-Xiang

    2014-05-20

    Solution processed silver nanowire indium-tin oxide nanoparticle (AgNW-ITONP) composite thin films were successfully applied as the transparent electrodes for Cu(In,Ga)Se₂ (CIGS) thin film solar cells with ZnS buffer layers. Properties of the AgNW-ITONP thin film and its effects on performance of CIGS/ZnS thin film solar cells were studied. Compared with the traditional sputtered ITO electrodes, the AgNW-ITONP thin films show comparable optical transmittance and electrical conductivity. Furthermore, the AgNW-ITONP thin film causes no physical damage to the adjacent surface layer and does not need high temperature annealing, which makes it very suitable to use as transparent conductive layers for heat or sputtering damage-sensitive optoelectronic devices. By using AgNW-ITONP electrodes, the required thickness of the ZnS buffer layers for CIGS thin film solar cells was greatly decreased. PMID:24922214

  6. 21 CFR 884.2685 - Fetal scalp clip electrode and applicator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... electrode applicator. (b) Classification. Class III (premarket approval). (c) Date PMA or notice of completion of a PDP is required. A PMA or a notice of completion of a PDP is required to be filed with the... shall have an approved PMA or a declared completed PDP in effect before being placed in...

  7. 21 CFR 884.2685 - Fetal scalp clip electrode and applicator.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... electrode applicator. (b) Classification. Class III (premarket approval). (c) Date PMA or notice of completion of a PDP is required. A PMA or a notice of completion of a PDP is required to be filed with the... shall have an approved PMA or a declared completed PDP in effect before being placed in...

  8. Prediction of transmittance spectra for transparent composite electrodes with ultra-thin metal layers

    NASA Astrophysics Data System (ADS)

    Zhao, Zhao; Khorasani, Arash Elhami; Theodore, N. D.; Dhar, A.; Alford, T. L.

    2015-11-01

    Recent interest in indium-free transparent composite-electrodes (TCEs) has motivated theoretical and experimental efforts to better understand and enhance their electrical and optical properties. Various tools have been developed to calculate the optical transmittance of multilayer thin-film structures based on the transfer-matrix method. However, the factors that affect the accuracy of these calculations have not been investigated very much. In this study, two sets of TCEs, TiO2/Au/TiO2 and TiO2/Ag/TiO2, were fabricated to study the factors that affect the accuracy of transmittance predictions. We found that the predicted transmittance can deviate significantly from measured transmittance for TCEs that have ultra-thin plasmonic metal layers. The ultrathin metal layer in the TCE is typically discontinuous. When light interacts with the metallic islands in this discontinuous layer, localized surface plasmons are generated. This causes extra light absorption, which then leads to the actual transmittance being lower than the predicted transmittance.

  9. Waste tire derived carbon-polymer composite paper as pseudocapacitive electrode with long cycle life

    DOE PAGESBeta

    Boota, M.; Paranthaman, Mariappan Parans; Naskar, Amit K.; Gogotsi, Yury; Li, Yunchao; Akato, Kokouvi

    2015-09-25

    Recycling hazardous wastes to produce value-added products is becoming essential for the sustainable progress of our society. Herein, highly porous carbon (1625 m2/g–1) is synthesized using waste tires as the precursor and used as supercapacitor electrode. The narrow pore size distribution (PSD) and high surface area led to a good charge storage capacity, especially when used as a three-dimensional nanoscaffold to polymerize polyaniline (PANI/TC). The composite film was highly flexible, conductive and exhibited a capacitance of 480 F/g–1 at 1 mV/s–1 with excellent capacitance retention up to 98% after 10,000 charge/discharge cycles. The high capacitance and long cycle life weremore » ascribed to the short diffusional paths, uniform PANI coating and tight confinement of the PANI in the inner pores of the tire-derived carbon via - interactions, which minimized the degradation of the PANI upon cycling. Here, we anticipate that the same strategy can be applied to deposit other pseudocapacitive materials with low-cost TC to achieve even higher electrochemical performance and longer cycle life, a key challenge for redox active polymers.« less

  10. Prediction of transmittance spectra for transparent composite electrodes with ultra-thin metal layers

    SciTech Connect

    Zhao, Zhao; Alford, T. L.; Khorasani, Arash Elhami; Theodore, N. D.; Dhar, A.

    2015-11-28

    Recent interest in indium-free transparent composite-electrodes (TCEs) has motivated theoretical and experimental efforts to better understand and enhance their electrical and optical properties. Various tools have been developed to calculate the optical transmittance of multilayer thin-film structures based on the transfer-matrix method. However, the factors that affect the accuracy of these calculations have not been investigated very much. In this study, two sets of TCEs, TiO{sub 2}/Au/TiO{sub 2} and TiO{sub 2}/Ag/TiO{sub 2}, were fabricated to study the factors that affect the accuracy of transmittance predictions. We found that the predicted transmittance can deviate significantly from measured transmittance for TCEs that have ultra-thin plasmonic metal layers. The ultrathin metal layer in the TCE is typically discontinuous. When light interacts with the metallic islands in this discontinuous layer, localized surface plasmons are generated. This causes extra light absorption, which then leads to the actual transmittance being lower than the predicted transmittance.

  11. Waste tire derived carbon-polymer composite paper as pseudocapacitive electrode with long cycle life

    SciTech Connect

    Boota, M.; Paranthaman, Mariappan Parans; Naskar, Amit K.; Gogotsi, Yury; Li, Yunchao; Akato, Kokouvi

    2015-09-25

    Recycling hazardous wastes to produce value-added products is becoming essential for the sustainable progress of our society. Herein, highly porous carbon (1625 m2/g–1) is synthesized using waste tires as the precursor and used as supercapacitor electrode. The narrow pore size distribution (PSD) and high surface area led to a good charge storage capacity, especially when used as a three-dimensional nanoscaffold to polymerize polyaniline (PANI/TC). The composite film was highly flexible, conductive and exhibited a capacitance of 480 F/g–1 at 1 mV/s–1 with excellent capacitance retention up to 98% after 10,000 charge/discharge cycles. The high capacitance and long cycle life were ascribed to the short diffusional paths, uniform PANI coating and tight confinement of the PANI in the inner pores of the tire-derived carbon via - interactions, which minimized the degradation of the PANI upon cycling. Here, we anticipate that the same strategy can be applied to deposit other pseudocapacitive materials with low-cost TC to achieve even higher electrochemical performance and longer cycle life, a key challenge for redox active polymers.

  12. Waste Tire Derived Carbon-Polymer Composite Paper as Pseudocapacitive Electrode with Long Cycle Life.

    PubMed

    Boota, M; Paranthaman, M Parans; Naskar, Amit K; Li, Yunchao; Akato, Kokouvi; Gogotsi, Y

    2015-11-01

    Recycling hazardous wastes to produce value-added products is becoming essential for the sustainable progress of our society. Herein, highly porous carbon (1625 m(2)  g(-1)) is synthesized using waste tires as the precursor and used as a supercapacitor electrode material. The narrow pore-size distribution and high surface area led to good charge storage capacity, especially when used as a three-dimensional nanoscaffold to polymerize polyaniline (PANI). The composite paper was highly flexible, conductive, and exhibited a capacitance of 480 F g(-1) at 1 mV s(-1) with excellent capacitance retention of up to 98% after 10,000 charge/discharge cycles. The high capacitance and long cycle life were ascribed to the short diffusional paths, uniform PANI coating, and tight confinement of the PANI in the inner pores of the tire-derived carbon through π-π interactions, which minimized the degradation of the PANI upon cycling. We anticipate that the same strategy can be applied to deposit other pseudocapacitive materials to achieve even higher electrochemical performance and longer cycle life-a key challenge for redox active polymers. PMID:26404735

  13. Electrochemical Performance of PbO2 and PbO2-CNT Composite Electrodes for Energy Storage Devices.

    PubMed

    Soumya, M S; Binitha, G; Praveen, P; Subramanian, K R V; Lee, Y S; Nair, V Shantikumar; Sivakumar, N

    2015-01-01

    In this work we report the electrochemical performance comparison of two new hybrid supercapacitors one based on graphene as negative electrode and lead dioxide thin film as positive electrode and the other with graphene as negative electrode and lead dioxide-carbon nanotube composite as positive electrode in 0.1 M KOH electrolyte. In the present work, PbO2 was synthesized using sol-gel method which is one of the promising materials for hybrid supercapacitors. The XRD confirmed the single phase of the PbO2 and the grain size is 39 nm which has been determined using Scherrer's formula. Thin films of PbO2, PbO2-CNT composite and graphene were coated on the titanium substrate by electrophoretic deposition. Further material characterisation has been carried out using SEM, TEM, XPS and electrochemical characterisation using CV, charge/discharge and electrochemical impedance spectroscopy (EIS) for obtaining energy density and power density, cyclic stability and internal resistance respectively. The present results revealed that PbO2-CNT composite/graphene asymmetric hybrid supercapacitor exhibits large specific capacitance and energy density over PbO2/graphene based system. The PbO2-CNT composite/graphene asymmetric hybrid supercapacitor exhibited maximum power density and energy density of 1200 W/Kg and 65 Wh/Kg respectively at a current density of 2 A/g. The PbO2-CNT composite/graphene asymmetric hybrid system exhibited excellent cycling stability with the capacitance retained 85% of its maximum value up to 3000 cycles. PMID:26328430

  14. MnO 2-Pt/C composite electrodes for preventing voltage reversal effects with polymer electrolyte membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Wei, Z. D.; Ji, M. B.; Hong, Y.; Sun, C. X.; Chan, S. H.; Shen, P. K.

    Water is produced at the cathode of proton-exchange membrane fuel cells (PEMFC). If water were not being removed effectively, it would accumulate at the cathode of PEMFC causing the electrode flooding. The consequence is oxygen starvation, thus increasing the concentration overpotential of the cathode. In the worst scenarios, a proton (H +) reduction reaction (PRR), instead of the oxygen reduction reaction (ORR), might occur at the cathode. Not only will this cause a cathode potential drop, but the output voltage of a single cell would likely be reversed due to oxygen starvation. This phenomenon is termed the voltage reversal effect (VRE) in this paper. To study and resolve the VRE problem, a MnO 2-Pt/C composite electrode was used to replace the conventional Pt/C electrode. The authors suggest that the electrochemical reduction of MnO 2 in the composite electrode has almost the same Nernstian potential as the ORR, which would serve as a substitute for the ORR in the case of oxygen starvation. Thus, the voltage reversal effect caused by the PRR could be avoided. Two environments, N 2- and O 2-saturated H 2SO 4, were adopted to simulate two cases, i.e., O 2 starvation and O 2 rich. It was found that MnO 2-Pt/C can prevent the voltage reversal effect to a certain extent. In a N 2-saturated 1 M H 2SO 4 solution, the current density of the Pt/C electrode made of 0.6 mg Pt cm -2 was close to 0, while for the MnO 2-Pt/C composite electrode made of 0.4 mg Pt cm -2 and 0.8 mg MnO 2 cm -2, it was as high as 10 mA cm -2. Though the current generated on the MnO 2-Pt/C composite electrode in the case of oxygen starvation is not as great as that in the case when oxygen rich, it might be high enough for some cases, such as powering a radio, hearing-aid and so like miniature devices. In an O 2-saturated 1 M H 2SO 4, the presence of MnO 2 in a MnO 2-Pt/C composite electrode primarily plays a catalytic role in the ORR. It enhances the catalytic behavior of Pt for the ORR. The

  15. Composite Materials for Low-Temperature Applications

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Composite materials with improved thermal conductivity and good mechanical strength properties should allow for the design and construction of more thermally efficient components (such as pipes and valves) for use in fluid-processing systems. These materials should have wide application in any number of systems, including ground support equipment (GSE), lunar systems, and flight hardware that need reduced heat transfer. Researchers from the Polymer Science and Technology Laboratory and the Cryogenics Laboratory at Kennedy Space Center were able to develop a new series of composite materials that can meet NASA's needs for lightweight materials/composites for use in fluid systems and also expand the plastic-additive markets. With respect to thermal conductivity and physical properties, these materials are excellent alternatives to prior composite materials and can be used in the aerospace, automotive, military, electronics, food-packaging, and textile markets. One specific application of the polymeric composition is for use in tanks, pipes, valves, structural supports, and components for hot or cold fluid-processing systems where heat flow through materials is a problem to be avoided. These materials can also substitute for metals in cryogenic and other low-temperature applications. These organic/inorganic polymeric composite materials were invented with significant reduction in heat transfer properties. Decreases of 20 to 50 percent in thermal conductivity versus that of the unmodified polymer matrix were measured. These novel composite materials also maintain mechanical properties of the unmodified polymer matrix. These composite materials consist of an inorganic additive combined with a thermoplastic polymer material. The intrinsic, low thermal conductivity of the additive is imparted into the thermoplastic, resulting in a significant reduction in heat transfer over that of the base polymer itself, yet maintaining most of the polymer's original properties. Normal

  16. Fungal Exopolysaccharide: Production, Composition and Applications

    PubMed Central

    Mahapatra, Subhadip; Banerjee, Debdulal

    2013-01-01

    Fungal exopolysaccharides (EPSs) have been recognized as high value biomacromolecules for the last two decades. These products, including pullulan, scleroglucan, and botryosphaeran, have several applications in industries, pharmaceuticals, medicine, foods etc. Although fungal EPSs are highly relevant, to date information concerning fungal biosynthesis is scarce and an extensive search for new fugal species that can produce novel EPSs is still needed. In most cases, the molecular weight variations and sugar compositions of fungal EPSs are dependent to culture medium composition and different physical conditions provided during fermentation. An inclusive and illustrative review on fungal EPS is presented here. The general outline of the present work includes fungal EPS production, their compositions and applications. An emphasis is also given to listing out different fungal strains that can produce EPSs. PMID:24826070

  17. Thermoplastic Composite Materials for Aerospace Applications

    NASA Astrophysics Data System (ADS)

    Casula, G.; Lenzi, F.; Vitiello, C.

    2008-08-01

    Mechanical and thermo-physical properties of composites materials with thermoplastic matrix (PEEK/IM7, TPI/IM7 and PPS/IM7) used for aerospace applications have been analyzed as function of two different process techniques: compression molding and fiber placement process "hot gas assisted."

  18. Fabrication and Characterization of a Micromachined Swirl-Shaped Ionic Polymer Metal Composite Actuator with Electrodes Exhibiting Asymmetric Resistance

    PubMed Central

    Feng, Guo-Hua; Liu, Kim-Min

    2014-01-01

    This paper presents a swirl-shaped microfeatured ionic polymer-metal composite (IPMC) actuator. A novel micromachining process was developed to fabricate an array of IPMC actuators on a glass substrate and to ensure that no shortcircuits occur between the electrodes of the actuator. We demonstrated a microfluidic scheme in which surface tension was used to construct swirl-shaped planar IPMC devices of microfeature size and investigated the flow velocity of Nafion solutions, which formed the backbone polymer of the actuator, within the microchannel. The unique fabrication process yielded top and bottom electrodes that exhibited asymmetric surface resistance. A tool for measuring surface resistance was developed and used to characterize the resistances of the electrodes for the fabricated IPMC device. The actuator, which featured asymmetric electrode resistance, caused a nonzero-bias current when the device was driven using a zero-bias square wave, and we propose a circuit model to describe this phenomenon. Moreover, we discovered and characterized a bending and rotating motion when the IPMC actuator was driven using a square wave. We observed a strain rate of 14.6% and a displacement of 700 μm in the direction perpendicular to the electrode surfaces during 4.5-V actuation. PMID:24824370

  19. Decolorization of C. I. Reactive Orange 4 and Textile Effluents by Electrochemical Oxidation Technique using Silver-Carbon Composite Electrode.

    PubMed

    Nordin, Norazzizi; Fathrita Mohd Amir, Siti; Rahimi Yusop, Muhammad; Rozali Othman, Mohamed

    2015-01-01

    In this study, the electrochemical oxidation of C. I. Reactive Orange 4 (RO4) on a silver-carbon composite (AgC-PVC) electrode was studied using the cyclic voltammetry, potential liner V, and electrolysis methods. The AgC-PVC electrode was used as the working electrode in the electrochemical measurement of RO4 in the presence of NaCl as a supporting electrolyte. The UV-Vis spectra of RO4 after the electrochemical oxidation showed the complete decolorization of the solution. The electrolysis products were characterized using FTIR and GC-MS. The results showed that in the presence of OCl- as an active oxidant, RO4 molecules are broken down into several lower-molecular-weight molecules by the electrochemical technique. The electrode used was also able to reduce the COD, BOD(5) and surfactant contents in the textile effluents using a pilot scale reactor. This proved that the prepared AgC-PVC electrode was beneficial for removing both the color and other pollutants from textile effluents. PMID:26454599

  20. Implication of composite electrode on the functioning of photo-bioelectrocatalytic fuel cell operated with heterotrophic-anoxygenic condition.

    PubMed

    Navaneeth, B; Hari Prasad, R; Chiranjeevi, P; Chandra, Rashmi; Sarkar, Omprakesh; Verma, Anil; Subudhi, Sanjukta; Lal, Banwari; Venkata Mohan, S

    2015-06-01

    Electrode materials play a vital role in biofilm formation and electron conduction for efficient functioning of fuel cells. In the present study, graphite polymer composite electrode (GPF) was evaluated as anode for photo-bioelectrocatalytic fuel cell (PhFC; biophotovoltaic system) and compared with much studied graphite electrode (Gc) with photosynthetic bacteria as biocatalyst under anoxygenic condition. The electrogenic activity noticed in GPF (584mV; 2.67mA) was slightly lower than Gc (604mV; 2.92mA; OL2/HRT2). Consequently, COD removal observed by GPF (87.3%) was lower than Gc (91.8%). The increase in bacterial chlorophyll pigment showed a positive influence on electrogenic activity for both the electrodes. The polarization resistance (OL2 and HRT2 condition) was significantly higher for GPF (330Ω) as compared to Gc (110Ω). It is interesting to note that the performance of GPF is slightly lower than Gc based PhFC. The findings have opened avenues for composite materials for PhFC. PMID:25795447

  1. Electrochemical study of Si/C composites with particulate and fibrous morphology as negative electrodes for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Gómez-Cámer, Juan Luis; Thuv, Heidi; Novák, Petr

    2015-10-01

    Silicon-carbon composites with two different morphologies, particulate and fibrous, prepared by NaOH catalyzed polymerization of resorcinol and formaldehyde in presence of Si nanoparticles and cosurfactants, are examined as negative electrodes in lithium-ion batteries. The composites prepared with ca. 33, 50, and 66% Si deliver around 1000, 1500, and 2000 mAh g-1, respectively. Higher silicon content results in higher initial specific charge, but also faster fading during cycling. The composites with the lowest silicon content exhibit the most stable specific charges. The differences in electrochemical behavior for the optimized compositions are investigated by means of microscopy and electrochemical impedance analysis and are discussed in terms of morphology of the different composites.

  2. Vanadium oxide (VO) based low cost counter electrode in dye sensitized solar cell (DSSC) applications

    SciTech Connect

    Vijayakumar, P.; Pandian, Muthu Senthil; Ramasamy, P.

    2015-06-24

    Vanadium oxide nanostars were synthesized by chemical method. The prepared Vanadium oxide nanostars are introduced into dye sensitized solar cell (DSSC) as counter electrode (CE) catalyst to replace the expensive platinum (Pt). The products were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and Brunauer–Emmett–Teller (BET) method. The photovoltaic performance of the VO as counter electrode based DSSC was evaluated under simulated standard global AM 1.5G sunlight (100 mW/cm{sup 2}). The solar to electrical energy conversion efficiency (η) of the DSSC was found to be 0.38%.This work expands the Counter electrode catalyst, which can help to reduce the cost of DSSC and thereby encourage their fundamental research and commercial application.

  3. In situ prepared transparent polyaniline electrode and its application in bifacial dye-sensitized solar cells.

    PubMed

    Tai, Qidong; Chen, Bolei; Guo, Feng; Xu, Sheng; Hu, Hao; Sebo, Bobby; Zhao, Xing-Zhong

    2011-05-24

    Highly uniform and transparent polyaniline (PANI) electrodes that can be used as counter electrodes in dye-sensitized solar cells (DSSCs) were prepared by a facile in situ polymerization method. They were used to fabricate a novel bifacially active transparent DSSC, which showed conversion efficiencies of 6.54 and 4.26% corresponding to front- and rear-side illumination, respectively. Meanwhile, the efficiency of the same photoanode employing a Pt counter electrode was 6.69%. Compared to conventional Pt-based DSSCs, the design of the bifacial DSSC fabricated in this work would help to bring down the cost of energy production due to the lower cost of the materials and the higher power-generating efficiency of such devices for their capabilities of utilizing the light from both sides. These promising results highlight the potential application of PANI in cost-effective, transparent DSSCs. PMID:21469717

  4. Fabrication of nanoporous thin-film working electrodes and their biosensing applications.

    PubMed

    Li, Tingjie; Jia, Falong; Fan, Yaxi; Ding, Zhifeng; Yang, Jun

    2013-04-15

    Electrochemical detection for point-of-care diagnostics is of great interest due to its high sensitivity, fast analysis time and ability to operate on a small scale. Herein, we report the fabrication of a nanoporous thin-film electrode and its application in the configuration of a simple and robust enzymatic biosensor. The nanoporous thin-film was formed in a planar gold electrode through an alloying/dealloying process. The nanoporous electrode has an electroactive surface area up to 40 times higher than that of a flat gold electrode of the same size. The nanoporous electrode was used as a substrate to build an enzymatic electrochemical biosensor for the detection of glucose in standard samples and control serum samples. The example glucose biosensor has a linear response up to 30 mM, with a high sensitivity of 0.50 μA mM⁻¹ mm⁻², and excellent anti-interference ability against lactate, uric acid and ascorbic acid. Abundant catalyst and enzyme were stably entrapped in the nanoporous structure, leading to high stability and reproducibility of the biosensor. Development of such nanoporous structure enables the miniaturization of high-performance electrochemical biosensors for point-of-care diagnostics or environmental field testing. PMID:23208085

  5. Facile 3D Metal Electrode Fabrication for Energy Applications via Inkjet Printing and Shape Memory Polymer

    NASA Astrophysics Data System (ADS)

    Roberts, R. C.; Wu, J.; Hau, N. Y.; Chang, Y. H.; Feng, S. P.; Li, D. C.

    2014-11-01

    This paper reports on a simple 3D metal electrode fabrication technique via inkjet printing onto a thermally contracting shape memory polymer (SMP) substrate. Inkjet printing allows for the direct patterning of structures from metal nanoparticle bearing liquid inks. After deposition, these inks require thermal curing steps to render a stable conductive film. By printing onto a SMP substrate, the metal nanoparticle ink can be cured and substrate shrunk simultaneously to create 3D metal microstructures, forming a large surface area topology well suited for energy applications. Polystyrene SMP shrinkage was characterized in a laboratory oven from 150-240°C, resulting in a size reduction of 1.97-2.58. Silver nanoparticle ink was patterned into electrodes, shrunk, and the topology characterized using scanning electron microscopy. Zinc-Silver Oxide microbatteries were fabricated to demonstrate the 3D electrodes compared to planar references. Characterization was performed using 10M potassium hydroxide electrolyte solution doped with zinc oxide (57g/L). After a 300s oxidation at 3Vdc, the 3D electrode battery demonstrated a 125% increased capacity over the reference cell. Reference cells degraded with longer oxidations, but the 3D electrodes were fully oxidized for 4 hours, and exhibited a capacity of 5.5mA-hr/cm2 with stable metal performance.

  6. Electromechanical filed concentrations and polarization switching due to interdigitated electrodes in piezoelectric macro-fiber composites under tension

    NASA Astrophysics Data System (ADS)

    Narita, Fumio; Shindo, Yasuhide; Sato, Koji; Takeda, Tomo

    2011-04-01

    This work investigates the electromechanical response of piezoelectric macro-fiber composites (MFCs) under tension. Nonlinear three dimensional finite element model incorporating the polarization switching mechanism was used to predict the electromechanical fields near interdigitated electrode (IDEs) in the piezoelectric MFCs. The lead zirconate titanate (PZT) fibers in the MFC are partially poled. The electric field-induced strain was then measured, and test results were presented to validate the predictions.

  7. Nanomechanical and Electro-mechanical Characterization of Materials for Flexible Electrodes Applications

    NASA Astrophysics Data System (ADS)

    Peng, Cheng

    Flexible electronics attract research and commercial interests in last 2 decades for its flexibility, low cost, light weight and etc. To develop and improve the electro-mechanical properties of flexible electrodes is the most critical and important step. In this work, we have performed nanomechanical and electromechanical characterization of materials for flexible electrode applications, including metallic nanowires (NWs), indium tin oxide (ITO)-based and carbon nanotube (CNT)-based electrodes. First, we designed and developed four different testing platforms for nanomechanical and electro-mechanical characterization purpose. For the nano/sub-micro size samples, the micro mechanical devices can be used for uniaxial and bi-axial loading tests. For the macro size samples, the micro tester will be used for in situ monotonic tensile test, while the fatigue tester can be used for in situ cyclic tensile or bending testing purpose. Secondly, we have investigated mechanical behaviors of single crystalline Ni nanowires and single crystalline Cu nanowires under uni-axial tensile loading inside a scanning electron microscope (SEM) chamber. We demonstrated both size and strain-rate dependence on yield stress of single-crystalline Ni NWs with varying diameters (from 100 nm to 300 nm), and the molecular dynamics (MD) simulation helped to confirm and understand the experimental phenomena. Also, two different fracture modes, namely ductile and brittle-like fractures, were found in the same batch of Cu nanowire samples. Finally, we studied the electro-mechanical behaviors of flexible electrodes in macro scale. We reported a coherent study integrating in situ electro-mechanical experiments and mechanics modeling to decipher the failure mechanics of ITO-based and CNTbased electrodes under tension. It is believed that our combined experimental and simulation results provide some further insights into the important yet complicated deformation mechanisms for nanoscale metals and

  8. Composite metal-hydrogen electrodes for metal-hydrogen batteries. Final report, October 1, 1993--April 15, 1997

    SciTech Connect

    Ruckman, M.W.; Strongin, M.; Weismann, H.

    1997-04-01

    The purpose of this project is to develop and conduct a feasibility study of metallic thin films (multilayered and alloy composition) produced by advanced sputtering techniques for use as anodes in Ni-metal hydrogen batteries that would be deposited as distinct anode, electrolyte and cathode layers in thin film devices. The materials could also be incorporated in secondary consumer batteries (i.e. type AF(4/3 or 4/5)) which use electrodes in the form of tapes. The project was based on pioneering studies of hydrogen uptake by ultra-thin Pd-capped Nb films, these studies suggested that materials with metal-hydrogen ratios exceeding those of commercially available metal hydride materials and fast hydrogen charging and discharging kinetics could be produced. The project initially concentrated on gas phase and electrochemical studies of Pd-capped niobium films in laboratory-scale NiMH cells. This extended the pioneering work to the wet electrochemical environment of NiMH batteries and exploited advanced synchrotron radiation techniques not available during the earlier work to conduct in-situ studies of such materials during hydrogen charging and discharging. Although batteries with fast charging kinetics and hydrogen-metal ratios approaching unity could be fabricated, it was found that oxidation, cracking and corrosion in aqueous solutions made pure Nb films and multilayers poor candidates for battery application. The project emphasis shifted to alloy films based on known elemental materials used for NiMH batteries. Although commercial NiMH anode materials contain many metals, it was found that 0.24 {mu}m thick sputtered Zr-Ni films cycled at least 50 times with charging efficiencies exceeding 95% and [H]/[M] ratios of 0.7-1.0. Multilayered or thicker Zr-Ni films could be candidates for a thin film NiMH battery that may have practical applications as an integrated power source for modern electronic devices.

  9. Composite Material Application to Liquid Rocket Engines

    NASA Technical Reports Server (NTRS)

    Judd, D. C.

    1982-01-01

    The substitution of reinforced plastic composite (RPC) materials for metal was studied. The major objectives were to: (1) determine the extent to which composite materials can be beneficially used in liquid rocket engines; (2) identify additional technology requirements; and (3) determine those areas which have the greatest potential for return. Weight savings, fabrication costs, performance, life, and maintainability factors were considered. Two baseline designs, representative of Earth to orbit and orbit to orbit engine systems, were selected. Weight savings are found to be possible for selected components with the substitution of materials for metal. Various technology needs are identified before RPC material can be used in rocket engine applications.

  10. Wearable energy-dense and power-dense supercapacitor yarns enabled by scalable graphene-metallic textile composite electrodes.

    PubMed

    Liu, Libin; Yu, You; Yan, Casey; Li, Kan; Zheng, Zijian

    2015-01-01

    One-dimensional flexible supercapacitor yarns are of considerable interest for future wearable electronics. The bottleneck in this field is how to develop devices of high energy and power density, by using economically viable materials and scalable fabrication technologies. Here we report a hierarchical graphene-metallic textile composite electrode concept to address this challenge. The hierarchical composite electrodes consist of low-cost graphene sheets immobilized on the surface of Ni-coated cotton yarns, which are fabricated by highly scalable electroless deposition of Ni and electrochemical deposition of graphene on commercial cotton yarns. Remarkably, the volumetric energy density and power density of the all solid-state supercapacitor yarn made of one pair of these composite electrodes are 6.1 mWh cm(-3) and 1,400 mW cm(-3), respectively. In addition, this SC yarn is lightweight, highly flexible, strong, durable in life cycle and bending fatigue tests, and integratable into various wearable electronic devices. PMID:26068809

  11. Wearable energy-dense and power-dense supercapacitor yarns enabled by scalable graphene–metallic textile composite electrodes

    PubMed Central

    Liu, Libin; Yu, You; Yan, Casey; Li, Kan; Zheng, Zijian

    2015-01-01

    One-dimensional flexible supercapacitor yarns are of considerable interest for future wearable electronics. The bottleneck in this field is how to develop devices of high energy and power density, by using economically viable materials and scalable fabrication technologies. Here we report a hierarchical graphene–metallic textile composite electrode concept to address this challenge. The hierarchical composite electrodes consist of low-cost graphene sheets immobilized on the surface of Ni-coated cotton yarns, which are fabricated by highly scalable electroless deposition of Ni and electrochemical deposition of graphene on commercial cotton yarns. Remarkably, the volumetric energy density and power density of the all solid-state supercapacitor yarn made of one pair of these composite electrodes are 6.1 mWh cm−3 and 1,400 mW cm−3, respectively. In addition, this SC yarn is lightweight, highly flexible, strong, durable in life cycle and bending fatigue tests, and integratable into various wearable electronic devices. PMID:26068809

  12. Polymeric ionic liquid and carbon black composite as a reusable supporting electrolyte: modification of the electrode surface.

    PubMed

    Yoo, Seung Joon; Li, Long-Ji; Zeng, Cheng-Chu; Little, R Daniel

    2015-03-16

    One of the major impediments to using electroorganic synthesis is the need for large amounts of a supporting electrolyte to ensure the passage of charge. Frequently this causes separation and waste problems. To address these issues, a polymeric ionic liquid-Super P carbon black composite has been formulated. The system enables electrolyses to be performed without adding an additional supporting electrolyte, and its efficient recovery and reuse. In addition, the ability of the composite to modify the electrode surface in situ leads to improved kinetics. A practical consequence is that one can decrease catalyst loading without sacrificing efficiency. PMID:25619992

  13. Perovskite electrodes and method of making the same

    DOEpatents

    Seabaugh, Matthew M.; Swartz, Scott L.

    2009-09-22

    The invention relates to perovskite oxide electrode materials in which one or more of the elements Mg, Ni, Cu, and Zn are present as minority components that enhance electrochemical performance, as well as electrode products with these compositions and methods of making the electrode materials. Such electrodes are useful in electrochemical system applications such as solid oxide fuel cells, ceramic oxygen generation systems, gas sensors, ceramic membrane reactors, and ceramic electrochemical gas separation systems.

  14. Perovskite electrodes and method of making the same

    SciTech Connect

    Seabaugh, Matthew M.; Swartz, Scott L.

    2005-09-20

    The invention relates to perovskite oxide electrode materials in which one or more of the elements Mg, Ni, Cu, and Zn are present as minority components that enhance electrochemical performance, as well as electrode products with these compositions and methods of making the electrode materials. Such electrodes are useful in electrochemical system applications such as solid oxide fuel cells, ceramic oxygen generation systems, gas sensors, ceramic membrane reactors, and ceramic electrochemical gas separation systems.

  15. Effect of Solution Composition on the Energy Production by Capacitive Mixing in Membrane-Electrode Assembly

    PubMed Central

    2015-01-01

    In this work, we consider the extent to which the presence of multivalent ions in solution modifies the equilibrium and dynamics of the energy production in a capacitive cell built with ion-exchange membranes in contact with high surface area electrodes. The cell potential in open circuit (OCV) is controlled by the difference between both membrane potentials, simulated as constant volume charge regions. A theoretical model is elaborated for steady state OCV, first in the case of monovalent solutions, as a reference. This is compared to the results in multi-ionic systems, containing divalent cations in concentrations similar to those in real seawater. It is found that the OCV is reduced by about 25% (as compared to the results in pure NaCl solutions) due to the presence of the divalent ions, even in low concentrations. Interestingly, this can be related to the “uphill” transport of such ions against their concentration gradients. On the contrary, their effect on the dynamics of the cell potential is negligible in the case of highly charged membranes. The comparison between model predictions and experimental results shows a very satisfactory agreement, and gives clues for the practical application of these recently introduced energy production methods. PMID:25089164

  16. A novel nitrite biosensor based on conductometric electrode modified with cytochrome c nitrite reductase composite membrane.

    PubMed

    Zhang, Zhiqiang; Xia, Siqing; Leonard, Didier; Jaffrezic-Renault, Nicole; Zhang, Jiao; Bessueille, François; Goepfert, Yves; Wang, Xuejiang; Chen, Ling; Zhu, Zhiliang; Zhao, Jianfu; Almeida, M Gabriela; Silveira, Célia M

    2009-02-15

    A conductometric biosensor for nitrite detection was developed using cytochrome c nitrite reductase (ccNiR) extracted from Desulfovibrio desulfuricans ATCC 27774 cells immobilized on a planar interdigitated electrode by cross-linking with saturated glutaraldehyde (GA) vapour in the presence of bovine serum albumin, methyl viologen (MV), Nafion, and glycerol. The configuration parameters for this biosensor, including the enzyme concentration, ccNiR/BSA ratio, MV concentration, and Nafion concentration, were optimized. Various experimental parameters, such as sodium dithionite added, working buffer solution, and temperature, were investigated with regard to their effect on the conductance response of the biosensor to nitrite. Under the optimum conditions at room temperature (about 25 degrees C), the conductometric biosensor showed a fast response to nitrite (about 10s) with a linear range of 0.2-120 microM, a sensitivity of 0.194 microS/microM [NO(2)(-)], and a detection limit of 0.05 microM. The biosensor also showed satisfactory reproducibility (relative standard deviation of 6%, n=5). The apparent Michaelis-Menten constant (K(M,app)) was 338 microM. When stored in potassium phosphate buffer (100mM, pH 7.6) at 4 degrees C, the biosensor showed good stability over 1 month. No obvious interference from other ionic species familiar in natural waters was detected. The application experiments show that the biosensor is suitable for use in real water samples. PMID:18804367

  17. Dechlorination of pentachlorophenol (PCP) in aqueous solution on novel Pd-loaded electrode modified with PPy-SDBS composite film.

    PubMed

    Sun, Zhirong; Wei, Xuefeng; Zhang, Huan; Hu, Xiang

    2015-03-01

    Pentachlorophenol (PCP) is a persistent pollutant and a suspected human carcinogen. It can be found in the air, water, and soil and enters the environment through evaporation from treated wood surfaces, industrial spills, and disposal at uncontrolled hazardous waste sites. Ecotoxicity of PCP necessitates the development of rapid and reliable remediation techniques. Electrocatalytic hydrogenolysis (ECH) has been proven as a promising method for detoxification of halogenated wastes, due to its rapid reaction rate, low apparatus cost, mild reaction conditions, and absence of secondary contaminants. Challenge for the application of ECH is to prepare a Pd-coated cathode with high stability, high catalytic activity, and low Pd loading level. In this work, Pd/polypyrrole-sodium dodecyl benzene sulfonate/meshed Ti (Pd/PPy-SDBS/Ti) electrode was prepared and was characterized by cyclic voltammetry, scanning electron microscopy, X-ray diffraction, and inductively coupled plasma-atomic emission spectrometry. Electrochemically reductive dechlorination of PCP on the Pd/PPy-SDBS/Ti electrode in aqueous solution was investigated. Pd microparticles were uniformly dispersed on PPy-SDBS film which was previously electrodeposited on the meshed Ti supporting electrode. The loading of Pd on the electrode was 0.72 mg cm(-2). Electrocatalytic dechlorination of PCP was performed in a two-compartment cell separated by cation-exchange membrane. The PCP removal on the Pd/PPy-SDBS/Ti electrode could reach 100 % within 70 min with dechlorination current 3 mA when PCP initial concentration was 10 mg L(-1) and initial pH was 2.4. Conversion of PCP on the Pd/PPy-SDBS/Ti electrode followed pseudo-first-order kinetics, and the apparent activation energy was 13.0 kJ mol(-1). The removal of PCP still kept 100 % after 70 min dechlorination when the Pd/PPy-SDBS/Ti cathode was reused ten times. The electrode exhibited promising dechlorination potential with high electrocatalytic activity, good stability

  18. Binder-free carbon black/stainless steel mesh composite electrode for high-performance anode in microbial fuel cells

    NASA Astrophysics Data System (ADS)

    Zheng, Suqi; Yang, Fangfang; Chen, Shuiliang; Liu, Lang; Xiong, Qi; Yu, Ting; Zhao, Feng; Schröder, Uwe; Hou, Haoqing

    2015-06-01

    Carbon black/stainless steel mesh (CB/SSM) composite electrodes were developed as high-performance anodes of microbial fuel cell (MFC) by using a binder-free dipping/drying method. The acid-treatment and thin layer of CB coating greatly improved the microbial adhesion of the electrode surface and facilitated the electron transfer between the bacteria and the electrode surface. As a result, a single-layer CB/SSM anode with thickness of 0.3 mm could generate a projected current density of about 1.53 ± 0.15 mA cm-2 and volumetic current density of 51.0 ± 5.0 mA cm-3, which was much higher than that of the bare SSM anode and conventional carbon felt anode with thickness of 2 mm. Moreover, three-dimensional (3D) CB/SSM electrode could be prepared by simple folding the singe-layer SSM, and produced a projected current density to 10.07 ± 0.88 mA cm-2 and a volumetric current density of 18.66 ± 1.63 mA cm-3. The MFC equipped with the 3D-CB/SSM anode produced a high maximum power density of 3215 ± 80 mW m-2. The CB/SSM electrodes showed good mechanical and electrical properties, excellent microbial adhesion; it represented a high-performance, low-cost electrode material that is easy to fabricate and scale-up.

  19. The role of 8 mol % yttria stabilized zirconia in the improvement of electrochemical performance of lanthanum manganite composite electrodes

    SciTech Connect

    Wang, S.; Jiang, Y.; Zhang, Y.; Yan, J.; Li, W.

    1998-06-01

    In this study, 8 mol % yttria stabilized zirconia (YSZ) + La{sub 0.8}Sr{sub 0.2}MnO{sub 3} (LSM) composite electrodes with addition of various amounts of YSZ were prepared on YSZ plates by a screen-printing method. The electrodes were then examined by scanning electron microscopy (SEM) and studied by ac impedance, cyclic voltammetry, and potential step as well as a polarization technique. For the oxygen reduction reaction on the pure LSM electrode, the dissociative adsorption of oxygen on the LSM surface and the transfer of oxygen ions from the triple-phase boundary (TPB) to the YSZ electrolyte lattice were found to be two comparable rate-determining steps. The electrochemical resistance of the former step was proportional to the {minus}0.5 power of p{sub O{sub 2}}, with a high activation energy of {approximately}2.0 eV. The electrochemical resistance of the latter step was found to be independent of p{sub O{sub 2}} with a low activation energy of {approximately}1.0 eV. With addition of YSZ to the LSM electrode, the electrochemical activity was improved substantially with much lower electrochemical resistances for both steps. Furthermore, the dissociative adsorption of oxygen became less rate determining on the electrode with more YSZ addition. It was found that the transfer of oxygen ion was the only rate-determining step on the 40% YSZ + LSM electrode. The improvement in the electrochemical performance with addition of YSZ was found mainly due to the spatial enlargement of the TPB area, which increased the electrochemically active sites for the oxygen adsorption and charge-transfer reaction.

  20. Self Healing Composite for Aircraft's Structural Application

    NASA Astrophysics Data System (ADS)

    Teoh, S. H.; Chia, H. Y.; Lee, M. S.; Nasyitah, A. J. N.; Luqman, H. B. S. M.; Nurhidayah, S.; Tan, Willy. C. K.

    When one cuts himself, it is amazing to watch how quickly the body acts to mend the wound. Immediately, the body works to pull the skin around the cut back together. The concept of repair by bleeding of enclosed functional agents serves as the biomimetic inspiration of synthetic self repair systems. Such synthetic self repair systems are based on advancement in polymeric materials; the process of human thrombosis is the inspiration for the application of self healing fibres within the composite materials. Results based on flexural 3 point bend test on the prepared samples have shown that the doubled layer healed hollow fibre laminate subjected to a healing regime of 3 weeks has a healed strength increase of 27% compared to the damaged baseline laminate. These results gave us confidence that there is a great potential to adopt such self healing mechanism on actual composite parts like in aircraft's composite structures.

  1. Microbubble Compositions, Properties and Biomedical Applications

    PubMed Central

    Sirsi, Shashank

    2010-01-01

    Over the last decade, there has been significant progress towards the development of microbubbles as theranostics for a wide variety of biomedical applications. The unique ability of microbubbles to respond to ultrasound makes them useful agents for contrast ultrasound imaging, molecular imaging, and targeted drug and gene delivery. The general composition of a microbubble is a gas core stabilized by a shell comprised of proteins, lipids or polymers. Each type of microbubble has its own unique advantages and can be tailored for specialized functions. In this review, different microbubbles compositions and physiochemical properties are discussed in the context of current progress towards developing novel constructs for biomedical applications, with specific emphasis on molecular imaging and targeted drug/gene delivery. PMID:20574549

  2. Applications of porous electrodes to metal-ion removal and the design of battery systems

    SciTech Connect

    Trost, G.G.

    1983-09-01

    This dissertation treats the use of porous electrodes as electrochemical reactors for the removal of dilute metal ions. A methodology for the scale-up of porous electrodes used in battery applications is given. Removal of 4 ..mu..g Pb/cc in 1 M sulfuric acid was investigated in atmospheric and high-pressure, flow-through porous reactors. The atmospheric reactor used a reticulated vitreous carbon porous bed coated in situ with a mercury film. Best results show 98% removal of lead from the feed stream. Results are summarized in a dimensionless plot of Sherwood number vs Peclet number. High-pressure, porous-electrode experiments were performed to investigate the effect of pressure on the current efficiency. Pressures were varied up to 120 bar on electrode beds of copper or lead-coated spheres. The copper spheres showed high hydrogen evolution rates which inhibited lead deposition, even at high cathodic overpotentials. Use of lead spheres inhibited hydrogen evolution but often resulted in the formation of lead sulfate layers; these layers were difficult to reduce back to lead. Experimental data of one-dimensional porous battery electrodes are combined with a model for the current collector and cell connectors to predict ultimate specific energy and maximum specific power for complete battery systems. Discharge behavior of the plate as a whole is first presented as a function of depth of discharge. These results are combined with the voltage and weight penalties of the interconnecting bus and post, positive and negative active material, cell container, etc. to give specific results for the lithium-aluminum/iron sulfide high-temperature battery. Subject to variation is the number of positive electrodes, grid conductivity, minimum current-collector weight, and total delivered capacity. The battery can be optimized for maximum energy or power, or a compromise design may be selected.

  3. Structural Ceramic Composites for Nuclear Applications

    SciTech Connect

    William Windes; P.A. Lessing; Y. Katoh; L. L. Snead; E. Lara-Curzio; J. Klett; C. Henager, Jr.; R. J. Shinavski

    2005-08-01

    A research program has been established to investigate fiber reinforced ceramic composites to be used as control rod components within a Very High Temperature Reactor. Two candidate systems have been identified, carbon fiber reinforced carbon (Cf/C) and silicon carbide fiber reinforced silicon carbide (SiCf/SiC) composites. Initial irradiation stability studies to determine the maximum dose for each composite type have been initiated within the High Flux Isotope Reactor at Oak Ridge National Laboratory. Test samples exposed to 10 dpa irradiation dose have been completed with future samples to dose levels of 20 and 30 dpa scheduled for completion in following years. Mechanical and environmental testing is being conducted concurrently at the Idaho National Laboratory and at Pacific Northwest National Laboratory. High temperature test equipment, testing methodologies, and test samples for high temperature (up to 1600º C) tensile strength and long duration creep studies have been established. Specific attention was paid to the architectural fiber preform design as well as the materials used in construction of the composites. Actual testing of both tubular and flat, "dog-bone" shaped tensile composite specimens will begin next year. Since there is no precedence for using ceramic composites within a nuclear reactor, ASTM standard test procedures will be established from these mechanical and environmental tests. Close collaborations between the U.S. national laboratories and international collaborators (i.e. France and Japan) are being forged to establish both national and international test standards to be used to qualify ceramic composites for nuclear reactor applications.

  4. Hybrid α-Fe2O3@Ni(OH)2 nanosheet composite for high-rate-performance supercapacitor electrode

    PubMed Central

    Jiang, Hong; Ma, Haifeng; Jin, Ying; Wang, Lanfang; Gao, Feng; Lu, Qingyi

    2016-01-01

    In this study, we report a facile fabrication of ultrathin two-dimensional (2D) nanosheet hybrid composite, α-Fe2O3 nanosheet@Ni(OH)2 nanosheet, by a two-step hydrothermal method to achieve high specific capacitance and good stability performance at high charging/discharging rates when serving as electrode material of supercapacitors. The α-Fe2O3@Ni(OH)2 hybrid electrode not only has a smooth decrease of the specific capacitance with increasing current density, compared with the sharp decline of single component of Ni(OH)2 electrode, but also presents excellent rate capability with a specific capacitance of 356 F/g at a current density of 16 A/g and excellent cycling stability (a capacity retention of 93.3% after 500 cycles), which are superior to the performances of Ni(OH)2 with a lower specific capacitance of 132 F/g and a lower capacity retention of 81.8% at 16 A/g. The results indicate such hybrid structure would be promising as excellent electrode material for good performances at high current densities in the future. PMID:27553663

  5. Hybrid α-Fe2O3@Ni(OH)2 nanosheet composite for high-rate-performance supercapacitor electrode.

    PubMed

    Jiang, Hong; Ma, Haifeng; Jin, Ying; Wang, Lanfang; Gao, Feng; Lu, Qingyi

    2016-01-01

    In this study, we report a facile fabrication of ultrathin two-dimensional (2D) nanosheet hybrid composite, α-Fe2O3 nanosheet@Ni(OH)2 nanosheet, by a two-step hydrothermal method to achieve high specific capacitance and good stability performance at high charging/discharging rates when serving as electrode material of supercapacitors. The α-Fe2O3@Ni(OH)2 hybrid electrode not only has a smooth decrease of the specific capacitance with increasing current density, compared with the sharp decline of single component of Ni(OH)2 electrode, but also presents excellent rate capability with a specific capacitance of 356 F/g at a current density of 16 A/g and excellent cycling stability (a capacity retention of 93.3% after 500 cycles), which are superior to the performances of Ni(OH)2 with a lower specific capacitance of 132 F/g and a lower capacity retention of 81.8% at 16 A/g. The results indicate such hybrid structure would be promising as excellent electrode material for good performances at high current densities in the future. PMID:27553663

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

    PubMed

    Baytak, Aysegul Kutluay; Duzmen, Sehriban; Teker, Tugce; Aslanoglu, Mehmet

    2015-12-01

    An electrochemical sensor was prepared by the modification of a glassy carbon electrode (GCE) with a composite of nanoparticles of tungsten oxide (WO3) and carbon nanotubes (CNTs) for the quantification of paracetamol (PR). Energy dispersive X-ray analysis (EDX) and scanning electron microscopy (SEM) were performed for the characterization of the nanocomposite layer. Compared with a bare GCE and a GCE modified with CNTs, the proposed electrode (WO3NPs/CNTs/GCE) exhibited a well-defined redox couple for PR and a marked enhancement of the current response. The experimental results also showed that ascorbic acid (AA) did not interfere with the selective determination of PR. The proposed electrode was used for the determination of PR in 0.1M phosphate buffer solution (PBS) at pH7.0 using square wave voltammetry (SWV). The peak current increased linearly with the concentration of PR in the range of 1.0×10(-9)-2.0×10(-7)M. The detection limit (LOD) was 5.54×10(-11)M (based on 3Sb/m). The proposed voltammetric sensor provided long-time stability, improved voltammetric behavior and good reproducibility for PR. The selective, accurate and precise determination of PR makes the proposed electrode of great interest for monitoring its therapeutic use. PMID:26354251

  7. Low-potential sensitive H2O2 detection based on composite micro tubular Te adsorbed on platinum electrode.

    PubMed

    Guascito, M R; Chirizzi, D; Malitesta, C; Mazzotta, E; M Siciliano; Siciliano, T; Tepore, A; Turco, A

    2011-04-15

    In this work a new original amperometric sensor for H(2)O(2) detection based on a Pt electrode modified with Te-microtubes was developed. Te-microtubes, synthesized by the simple thermal evaporation of Te powder, have a tubular structure with a hexagonal cross-section and are open ended. Modified electrode was prepared by direct drop casting of the mixture of Te-microtubes dispersed in ethanol on Pt surface. The spectroscopic characterization of synthesized Te-microtubes and Pt/Te-microtubes modified electrodes was performed by scanning electron microscopy (SEM), energy-dispersive X-rays microanalysis (EDX), X-ray diffraction analysis (XRD) and X-ray photoelectron spectroscopy (XPS). Moreover a complete electrochemical characterization of the new composite material Pt/Te-microtubes was performed by cyclic voltammetry (CV) and cronoamperometry (CA) in phosphate buffer solution (PBS) at pH 7. Electrochemical experiments showed that the presence of Te-microtubes on modified electrode was responsible for an increment of both cathodic and anodic currents in presence of H(2)O(2) with respect to bare Pt. Specifically, data collected from amperometric experiments at -150 mV vs. SCE in batch and -200 mV vs. SCE in flow injection analysis (FIA) experiments show a remarkable increment of the cathodic current. The electrochemical performances of tested sensors make them suitable for the quantitative determination of H(2)O(2) substrate both in batch and in FIA. PMID:21377859

  8. Fabrication, characterization of two nano-composite CuO-ZnO working electrodes for dye-sensitized solar cell.

    PubMed

    Habibi, Mohammad Hossein; Karimi, Bahareh; Zendehdel, Mahmoud; Habibi, Mehdi

    2013-12-01

    Two kind of CuO-ZnO nanocomposite working electrodes were synthesized by sol-gel technology and applied in dye-sensitized solar cells (DSSCs). Their characteristics were studied by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and UV-Vis diffuse reflectance spectrum (DRS). CuO-ZnO nanocomposite thin films were prepared doctor blade technique on the fluorine-doped tin oxide (FTO) and used as working electrodes in dye sensitized solar cells (DSSC). Their photovoltaic behavior were compared with standard using D35 dye and an electrolyte containing [Co(bpy)3](PF6)2, [Co(pby)3](PF6)3, LiClO4, and 4-tert-butylpyridine (TBP). The ranges of short-circuit current (JSC) from 0.18 to 0.21 (mA/cm(2)), open-circuit voltage (VOC) from 0.24 to 0.55V, and fill factor from 0.34 to 0.39 were obtained for the DSSCs made using the working electrodes. The efficiency of the working electrodes after the addition of TBL was more than doubled. The light scattering and carrier transport properties of these composites promote the performance of dye-sensitized solar cells (DSSCs). PMID:23973582

  9. Continuous Preparation of Copper/Carbon Nanotube Composite Films and Application in Solar Cells.

    PubMed

    Luo, Xiao Gang; Le Wu, Min; Wang, Xiao Xia; Zhong, Xin Hua; Zhao, Ke; Wang, Jian Nong

    2016-02-01

    Realizing the continuous and large scale preparation of particle/carbon nanotube (CNT) composites with enhanced functionalities, and broad applications in energy conversion, harvesting, and storage systems, remains as a big challenge. Here, we report a scalable strategy to continuously prepare particle/CNT composite films in which particles are confined by CNT films. This is achieved by the continuous condensation and deposition of a cylindrical assembly of CNTs on a paper strip and the in situ incorporation of particles during the layer-by-layer deposition process. A Cu/CNT composite film is prepared as an example; such a film exhibits very high power conversion efficiency when it is used as a counter electrode in a solar cell, compared with previous materials under otherwise identical conditions. The proposed method can be extended to other CNT-based composite films with excellent functionalities for wide applications. PMID:26784865

  10. Recent development of carbon electrode materials and their bioanalytical and environmental applications.

    PubMed

    Zhang, Wei; Zhu, Shuyun; Luque, Rafael; Han, Shuang; Hu, Lianzhe; Xu, Guobao

    2016-02-01

    Carbon materials have been extensively investigated due to their diversity, favorable properties, and active applications including electroanalytical chemistry. This critical review discusses new synthetic methods, novel carbon materials, new properties and electroanalytical applications of carbon materials particularly related to the preparation as well as bioanalytical and environmental applications of highly oriented pyrolytic graphite, graphene, carbon nanotubes, various carbon films (e.g. pyrolyzed carbon films, boron-doped diamond films and diamond-like carbon films) and screen printing carbon electrodes. Future perspectives in the field have also been discussed (366 references). PMID:26662473

  11. Nanocellulose coupled flexible polypyrrole@graphene oxide composite paper electrodes with high volumetric capacitance

    NASA Astrophysics Data System (ADS)

    Wang, Zhaohui; Tammela, Petter; Strømme, Maria; Nyholm, Leif

    2015-02-01

    A robust and compact freestanding conducting polymer-based electrode material based on nanocellulose coupled polypyrrole@graphene oxide paper is straightforwardly prepared via in situ polymerization for use in high-performance paper-based charge storage devices, exhibiting stable cycling over 16 000 cycles at 5 A g-1 as well as the largest specific volumetric capacitance (198 F cm-3) so far reported for flexible polymer-based electrodes.A robust and compact freestanding conducting polymer-based electrode material based on nanocellulose coupled polypyrrole@graphene oxide paper is straightforwardly prepared via in situ polymerization for use in high-performance paper-based charge storage devices, exhibiting stable cycling over 16 000 cycles at 5 A g-1 as well as the largest specific volumetric capacitance (198 F cm-3) so far reported for flexible polymer-based electrodes. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr07251k

  12. Ni-BaTiO3-Based Base-Metal Electrode (BME) Ceramic Capacitors for Space Applications

    NASA Technical Reports Server (NTRS)

    Liu, Donhang; Fetter, Lula; Meinhold, Bruce

    2015-01-01

    A multi-layer ceramic capacitor (MLCC) is a high-temperature (1350C typical) co-fired ceramic monolithic that is composed of many layers of alternately stacked oxide-based dielectric and internal metal electrodes. To make the dielectric layers insulating and the metal electrode layers conducting, only highly oxidation-resistant precious metals, such as platinum, palladium, and silver, can be used for the co-firing of insulating MLCCs in a regular air atmosphere. MLCCs made with precious metals as internal electrodes and terminations are called precious-metal electrode (PME) capacitors. Currently, all military and space-level applications only address the use of PME capacitors.

  13. Disposable Non-Enzymatic Glucose Sensors Using Screen-Printed Nickel/Carbon Composites on Indium Tin Oxide Electrodes.

    PubMed

    Jeon, Won-Yong; Choi, Young-Bong; Kim, Hyug-Han

    2015-01-01

    Disposable screen-printed nickel/carbon composites on indium tin oxide (ITO) electrodes (DSPNCE) were developed for the detection of glucose without enzymes. The DSPNCE were prepared by screen-printing the ITO substrate with a 50 wt% nickel/carbon composite, followed by curing at 400 °C for 30 min. The redox couple of Ni(OH)₂/NiOOH was deposited on the surface of the electrodes via cyclic voltammetry (CV), scanning from 0-1.5 V for 30 cycles in 0.1 M NaOH solution. The DSPNCE were characterized by field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and electrochemical methods. The resulting electrical currents, measured by CV and chronoamperometry at 0.65 V vs. Ag/AgCl, showed a good linear response with glucose concentrations from 1.0-10 mM. Also, the prepared electrodes showed no interference from common physiologic interferents such as uric acid (UA) or ascorbic acid (AA). Therefore, this approach allowed the development of a simple, disposable glucose biosensor. PMID:26690438

  14. Disposable Non-Enzymatic Glucose Sensors Using Screen-Printed Nickel/Carbon Composites on Indium Tin Oxide Electrodes

    PubMed Central

    Jeon, Won-Yong; Choi, Young-Bong; Kim, Hyug-Han

    2015-01-01

    Disposable screen-printed nickel/carbon composites on indium tin oxide (ITO) electrodes (DSPNCE) were developed for the detection of glucose without enzymes. The DSPNCE were prepared by screen-printing the ITO substrate with a 50 wt% nickel/carbon composite, followed by curing at 400 °C for 30 min. The redox couple of Ni(OH)2/NiOOH was deposited on the surface of the electrodes via cyclic voltammetry (CV), scanning from 0–1.5 V for 30 cycles in 0.1 M NaOH solution. The DSPNCE were characterized by field-emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), and electrochemical methods. The resulting electrical currents, measured by CV and chronoamperometry at 0.65 V vs. Ag/AgCl, showed a good linear response with glucose concentrations from 1.0–10 mM. Also, the prepared electrodes showed no interference from common physiologic interferents such as uric acid (UA) or ascorbic acid (AA). Therefore, this approach allowed the development of a simple, disposable glucose biosensor. PMID:26690438

  15. A Graphene Composite Material with Single Cobalt Active Sites: A Highly Efficient Counter Electrode for Dye-Sensitized Solar Cells.

    PubMed

    Cui, Xiaoju; Xiao, Jianping; Wu, Yihui; Du, Peipei; Si, Rui; Yang, Huaixin; Tian, Huanfang; Li, Jianqi; Zhang, Wen-Hua; Deng, Dehui; Bao, Xinhe

    2016-06-01

    The design of catalysts that are both highly active and stable is always challenging. Herein, we report that the incorporation of single metal active sites attached to the nitrogen atoms in the basal plane of graphene leads to composite materials with superior activity and stability when used as counter electrodes in dye-sensitized solar cells (DSSCs). A series of composite materials based on different metals (Mn, Fe, Co, Ni, and Cu) were synthesized and characterized. Electrochemical measurements revealed that CoN4 /GN is a highly active and stable counter electrode for the interconversion of the redox couple I(-) /I3 (-) . DFT calculations revealed that the superior properties of CoN4 /GN are due to the appropriate adsorption energy of iodine on the confined Co sites, leading to a good balance between adsorption and desorption processes. Its superior electrochemical performance was further confirmed by fabricating DSSCs with CoN4  /GN electrodes, which displayed a better power conversion efficiency than the Pt counterpart. PMID:27089044

  16. Modification of the surface morphology of the silicon substrate for boron-doped diamond electrodes in electrochemical wastewater treatment applications

    NASA Astrophysics Data System (ADS)

    Bak, Ji-Yoon; Lee, Choong-Hyun; Kim, Jung-Do; Lim, Dae-Soon

    2016-01-01

    For electrochemical wastewater treatment applications, textured boron-doped diamond (BDD) electrodes were fabricated by using a simple and cost-effective etching process. On the basis of the surface area measurement, the etching time was optimized in order to achieve higher electrochemical wastewater treatment performance. The surface structure, electrochemical properties, and electrochemical oxidation performance of the electrodes were characterized by using Raman spectroscopy and atomic force microscopy, in addition to electrochemical techniques. The textured BDD electrode demonstrated a dense and large surface area with no change in the film's properties. The effective surface area of the textured BDD electrode was approximately twice as large as that of the planar BDD electrode. The electrochemical results clearly demonstrate that the enhanced surface area of the BDD electrode achieves a higher current efficiency and much lower energy consumption in the electrochemical oxidation of methyl-orange.

  17. Nanoscale electrode arrays produced with microscale lithographic techniques for use in biomedical sensing applications.

    PubMed

    Terry, Jonathan G; Schmüser, Ilka; Underwood, Ian; Corrigan, Damion K; Freeman, Neville J; Bunting, Andrew S; Mount, Andrew R; Walton, Anthony J

    2013-12-01

    A novel technique for the production of nanoscale electrode arrays that uses standard microfabrication processes and micron-scale photolithography is reported here in detail. These microsquare nanoband edge electrode (MNEE) arrays have been fabricated with highly reproducible control of the key array dimensions, including the size and pitch of the individual elements and, most importantly, the width of the nanoband electrodes. The definition of lateral features to nanoscale dimensions typically requires expensive patterning techniques that are complex and low-throughput. However, the fabrication methodology used here relies on the fact that vertical dimensions (i.e. layer thicknesses) have long been manufacturable at the nanoscale using thin film deposition techniques that are well established in mainstream microelectronics. The authors report for the first time two aspects that highlight the particular suitability of these MNEE array systems for probe monolayer biosensing. The first is simulation, which shows the enhanced sensitivity to the redox reaction of the solution redox couple. The second is the enhancement of probe film functionalisation observed for the probe film model molecule, 6-mercapto-1-hexanol compared with microsquare electrodes. Such surface modification for specific probe layer biosensing and detection is of significance for a wide range of biomedical and other sensing and analytical applications. PMID:24206769

  18. Graphene-based carbon-layered electrode array technology for neural imaging and optogenetic applications

    PubMed Central

    Park, Dong-Wook; Schendel, Amelia A.; Mikael, Solomon; Brodnick, Sarah K.; Richner, Thomas J.; Ness, Jared P.; Hayat, Mohammed R.; Atry, Farid; Frye, Seth T.; Pashaie, Ramin; Thongpang, Sanitta; Ma, Zhenqiang; Williams, Justin C.

    2014-01-01

    Neural micro-electrode arrays that are transparent over a broad wavelength spectrum from ultraviolet to infrared could allow for simultaneous electrophysiology and optical imaging, as well as optogenetic modulation of the underlying brain tissue. The long-term biocompatibility and reliability of neural micro-electrodes also require their mechanical flexibility and compliance with soft tissues. Here we present a graphene-based, carbon-layered electrode array (CLEAR) device, which can be implanted on the brain surface in rodents for high-resolution neurophysiological recording. We characterize optical transparency of the device at >90% transmission over the ultraviolet to infrared spectrum and demonstrate its utility through optical interface experiments that use this broad spectrum transparency. These include optogenetic activation of focal cortical areas directly beneath electrodes, in vivo imaging of the cortical vasculature via fluorescence microscopy and 3D optical coherence tomography. This study demonstrates an array of interfacing abilities of the CLEAR device and its utility for neural applications. PMID:25327513

  19. Enzymatic deposition of Au nanoparticles on the designed electrode surface and its application in glucose detection.

    PubMed

    Zhang, Hongfang; Liu, Ruixiao; Sheng, Qinglin; Zheng, Jianbin

    2011-02-01

    This paper reported the enzymatic deposition of Au nanoparticles (AuNPs) on the designed 3-mercapto-propionic acid/glucose oxidase/chitosan (MPA/GOD/Chit) modified glassy carbon electrode and its application in glucose detection. Chit served as GOD immobilization matrix and interacted with MPA through electrostatic attraction. AuNPs, without nano-seeds presented on the electrode surface, was produced through the glucose oxidase catalyzed oxidation of glucose. The mechanism of production of AuNPs was confirmed to be that enzymatic reaction products H(2)O(2) in the solution reduce gold complex to AuNPs. The characterizations of the electrode modified after each assembly step was investigated by cyclic voltammetry and electrochemical impedance spectroscopy. Scanning electron microscopy showed the average particle size of the AuNPs is 40nm with a narrow particle size distribution. The content of AuNPs on the electrode surfaces was measured by differential pulse stripping voltammetry. The electrochemical signals on voltammogram showed a linear increase with the glucose concentration in the range of 0.010-0.12mM with a detection limit of 4μM. This provided a method to the determination of glucose. PMID:21115279

  20. Application of graphene oxide/lanthanum-modified carbon paste electrode for the selective determination of dopamine

    NASA Astrophysics Data System (ADS)

    Ye, Fengying; Feng, Chenqi; Fu, Ning; Wu, Huihui; Jiang, Jibo; Han, Sheng

    2015-12-01

    A home-made carbon paste electrode (CPE) was reformed by graphene oxide (GO)/lanthanum (La) complexes, and a modified electrode, called GO-La/CPE, was fabricated for the selective determination of dopamine (DA) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Several factors affecting the electrocatalytic performance of the modified sensor were investigated. Owning to the combination of GO and La ions, the GO-La/CPE sensor exhibited large surface area, well selectivity, good repeatability and stability in the oxidation reaction of DA. At optimal conditions, the response of the GO-La/CPE electrode for determining DA was linear in the region of 0.01-0.1 μM and 0.1-400.0 μM. The limit of detection was down to 0.32 nM (S/N = 3). In addition, this modified electrode was successfully applied to the detection of DA in real urine and serum samples by using standard adding method, showing its promising application in the electroanalysis of real samples.

  1. Enhancing electrocatalytic performance of Sb-doped SnO ₂ electrode by compositing nitrogen-doped graphene nanosheets.

    PubMed

    Duan, Tigang; Wen, Qing; Chen, Ye; Zhou, Yiding; Duan, Ying

    2014-09-15

    An efficient Ti/Sb-SnO2 electrode modified with nitrogen-doped graphene nanosheets (NGNS) was successfully fabricated by the sol-gel and dip coating method. Compared with Ti/Sb-SnO2 electrode, the NGNS-modified electrode possesses smaller unite crystalline volume (71.11Å(3) vs. 71.32Å(3)), smaller electrical resistivity (13Ωm vs. 34Ωm), and lower charge transfer resistance (10.91Ω vs. 21.01Ω). The accelerated lifetime of Ti/Sb-SnO2-NGNS electrode is prolonged significantly, which is 4.45 times as long as that of Ti/Sb-SnO2 electrode. The results of X-ray photoelectron spectroscopy measurement and voltammetric charge analysis indicate that introducing NGNS into the active coating can increase more reaction active sites to enhance the electrocatalytic efficiency. The electrochemical dye decolorization analysis demonstrates that Ti/Sb-SnO2-NGNS presents efficient electrocatalytic performance for methylene blue and orange II decolorization. And its pseudo-first order kinetic rate constants for methylene blue and orange II decolorization are 36.6 and 44.0 min(-1), respectively, which are 6.0 and 7.1 times as efficient as those of Ti/Sb-SnO2, respectively. Considering the significant electrocatalytic activity and low resistivity of Ti/Sb-SnO2-NGNS electrode, the cost of wastewater treatment can be expected to be reduced obviously and the application prospect is broad. PMID:25179102

  2. Flexible transparent conducting composite films using a monolithically embedded AgNW electrode with robust performance stability.

    PubMed

    Im, Hyeon-Gyun; Jin, Jungho; Ko, Ji-Hoon; Lee, Jaemin; Lee, Jung-Yong; Bae, Byeong-Soo

    2014-01-21

    We report on the performance of an all-in-one flexible hybrid conducting film employing a monolithically embedded AgNW transparent electrode and a high-performance glass-fabric reinforced composite substrate (AgNW-GFRHybrimer film). Specifically, we perform in-depth investigations on the stability of the AgNW-GFRHybrimer film against heat, thermal oxidation, and wet chemicals to demonstrate the potential of the hybrid conducting film as a robust electrode platform for thin-film optoelectronic devices. With the ease of large-area processability, smooth surface topography, and robust performance stability, the AgNW-GFRHybrimer film can be a promising platform for high-performance optoelectronic devices. PMID:24284890

  3. Electrochemical determination of Sudan I in food products using a carbon nanotube-ionic liquid composite modified electrode.

    PubMed

    Liu, Benzhi; Yin, Chuntao; Wang, Min

    2014-01-01

    A sensitive and convenient electrochemical method was developed for the determination of Sudan I using a carbon nanotube-ionic liquid composite modified electrode with the enhancement effect of cetyltrimethyl ammonium bromide (CTAB). The modified electrode exhibited an obvious electrocatalytic activity towards the oxidation of Sudan I, and the oxidation peak current significantly increased in the presence of CTAB. The experimental parameters, such as solution pH, concentration of CTAB and accumulation time, were optimised for Sudan I determination. The oxidation peak current showed a linear relationship with the concentration of Sudan I in the range of 3.0 × 10(-8) to 3.1 × 10(-6) mol l(-1), with a detection limit of 8.0 × 10(-9) mol l(-1). The proposed method was successfully applied for the determination of Sudan I in food products of ketchup and chilli sauce. PMID:25254422

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  5. Impact of electrode composition on electricity generation in a single-compartment fuel cell using Shewanella putrefaciens.

    PubMed

    Park, D H; Zeikus, J G

    2002-06-01

    The production of electricity by Shewanella putrefaciens in the absence of exogenous electron acceptors was examined in a single compartment fuel cell with different types of electrodes and varying physiological conditions. Electricity production was dependent on anode composition, electron donor type and cell concentration. A maximum current of 2.5 mA and a current density of 10.2 mW/m(2)electrode was obtained with a Mn(4+) graphite anode, 200 mM sodium lactate and a cell concentration of 3.9 g cell protein/ml. Current production by S. putrefaciens was enhanced 10-fold when an electron mediator (i.e., Mn(4+) or neutral red) was incorporated into the graphite anode. PMID:12073132

  6. Application of atmospheric pressure plasma in polymer and composite adhesion

    NASA Astrophysics Data System (ADS)

    Yu, Hang

    An atmospheric pressure helium and oxygen plasma was used to investigate surface activation and bonding in polymer composites. This device was operated by passing 1.0-3.0 vol% of oxygen in helium through a pair of parallel plate metal electrodes powered by 13.56 or 27.12 MHz radio frequency power. The gases were partially ionized between the capacitors where plasma was generated. The reactive species in the plasma were carried downstream by the gas flow to treat the substrate surface. The temperature of the plasm gas reaching the surface of the substrate did not exceed 150 °C, which makes it suitable for polymer processing. The reactive species in the plasma downstream includes ~ 1016-1017 cm-3 atomic oxygen, ~ 1015 cm-3 ozone molecule, and ~ 10 16 cm-3 metastable oxygen molecule (O2 1Deltag). The substrates were treated at 2-5 mm distance from the exit of the plasma. Surface properties of the substrates were characterized using water contact angle (WCA), atomic force microscopy (AFM), infrared spectroscopy (IR), and X-ray photoelectron spectroscopy (XPS). Subsequently, the plasma treated samples were bonded adhesively or fabricated into composites. The increase in mechanical strength was correlated to changes in the material composition and structure after plasma treatment. The work presented hereafter establishes atmospheric pressure plasma as an effective method to activate and to clean the surfaces of polymers and composites for bonding. This application can be further expanded to the activation of carbon fibers for better fiber-resin interactions during the fabrication of composites. Treating electronic grade FR-4 and polyimide with the He/O2 plasma for a few seconds changed the substrate surface from hydrophobic to hydrophilic, which allowed complete wetting of the surface by epoxy in underfill applications. Characterization of the surface by X-ray photoelectron spectroscopy shows formation of oxygenated functional groups, including hydroxyl, carbonyl, and

  7. Scanning electrochemical microscope characterization of thin film combinatorial libraries for fuel cell electrode applications

    NASA Astrophysics Data System (ADS)

    Black, M.; Cooper, J.; McGinn, P.

    2005-01-01

    Pt-Ru combinatorial libraries of potential fuel cell anode catalysts are formed by sequential sputter deposition through masks onto Si wafers. Scanning electrochemical microscopy (SECM) is employed for characterization of electrocatalytic activity. Aspects of using a scanning electrochemical microscope for characterization of an array of thin film fuel cell electrode materials are discussed. It is shown that in applying SECM to library characterization, careful attention must be paid to thin film annealing, specimen topography and tip degradation in order to realize meaningful results. Results from a Pt-Ru thin film library reveal the most active members near the 50 Pt/50 Ru composition.

  8. Flexible transparent conducting composite films using a monolithically embedded AgNW electrode with robust performance stability

    NASA Astrophysics Data System (ADS)

    Im, Hyeon-Gyun; Jin, Jungho; Ko, Ji-Hoon; Lee, Jaemin; Lee, Jung-Yong; Bae, Byeong-Soo

    2013-12-01

    We report on the performance of an all-in-one flexible hybrid conducting film employing a monolithically embedded AgNW transparent electrode and a high-performance glass-fabric reinforced composite substrate (AgNW-GFRHybrimer film). Specifically, we perform in-depth investigations on the stability of the AgNW-GFRHybrimer film against heat, thermal oxidation, and wet chemicals to demonstrate the potential of the hybrid conducting film as a robust electrode platform for thin-film optoelectronic devices. With the ease of large-area processability, smooth surface topography, and robust performance stability, the AgNW-GFRHybrimer film can be a promising platform for high-performance optoelectronic devices.We report on the performance of an all-in-one flexible hybrid conducting film employing a monolithically embedded AgNW transparent electrode and a high-performance glass-fabric reinforced composite substrate (AgNW-GFRHybrimer film). Specifically, we perform in-depth investigations on the stability of the AgNW-GFRHybrimer film against heat, thermal oxidation, and wet chemicals to demonstrate the potential of the hybrid conducting film as a robust electrode platform for thin-film optoelectronic devices. With the ease of large-area processability, smooth surface topography, and robust performance stability, the AgNW-GFRHybrimer film can be a promising platform for high-performance optoelectronic devices. Electronic supplementary information (ESI) available: Further characteristics of AgNW-GFRHybrimer films and thermal oxidation of AgNW on glass. See DOI: 10.1039/c3nr05348b

  9. Development of molecular precursors for deposition of indium sulphide thin film electrodes for photoelectrochemical applications.

    PubMed

    Ehsan, Muhammad Ali; Peiris, T A Nirmal; Wijayantha, K G Upul; Olmstead, Marilyn M; Arifin, Zainudin; Mazhar, Muhammad; Lo, K M; McKee, Vickie

    2013-08-14

    Symmetrical and unsymmetrical dithiocarbamato pyridine solvated and non-solvated complexes of indium(III) with the general formula [In(S2CNRR')3]·n(py) [where py = pyridine; R,R' = Cy, n = 2 (1); R,R' = (i)Pr, n = 1.5 (2); NRR' = Pip, n = 0.5 (3) and R = Bz, R' = Me, n = 0 (4)] have been synthesized. The compositions, structures and properties of these complexes have been studied by means of microanalysis, IR and (1)H-NMR spectroscopy, X-ray single crystal and thermogravimetric (TG/DTG) analyses. The applicability of these complexes as single source precursors (SSPs) for the deposition of β-In2S3 thin films on fluorine-doped SnO2 (FTO) coated conducting glass substrates by aerosol-assisted chemical vapour deposition (AACVD) at temperatures of 300, 350 and 400 °C is studied. All films have been characterized by powder X-ray diffraction (PXRD) and energy dispersive X-ray analysis (EDX) for the detection of phase and stoichiometry of the deposit. Scanning electron microscopy (SEM) studies reveal that precursors (1)-(4), irrespective of different metal ligand design, generate comparable morphologies of β-In2S3 thin films at different temperatures. Direct band gap energies of 2.2 eV have been estimated from the UV-vis spectroscopy for the β-In2S3 films fabricated from precursors (1) and (4). The photoelectrochemical (PEC) properties of β-In2S3 were confirmed by recording the current-voltage plots under light and dark conditions. The plots showed anodic photocurrent densities of 1.25 and 0.65 mA cm(-2) at 0.23 V vs. Ag/AgCl for the β-In2S3 films made at 400 and 350 °C from the precursors (1) and (4), respectively. The photoelectrochemical performance indicates that the newly synthesised precursors are highly useful in fabricating β-In2S3 electrodes for solar energy harvesting and optoelectronic application. PMID:23787951

  10. Marine applications for advanced composite materials

    SciTech Connect

    Hihara, L.H.; Bregman, R.; Takahashi, P.K.

    1993-12-31

    Very large floating structures (VLFSs) may one day be essential to the study and utilization of the ocean. Some possible applications for VLFSs are ocean ranching homeports. observatories for ocean research, seabed mineral refineries, energy generation platforms. and waste management facilities. A VLFS that is in the conceptual phase, and may one day be based off the coast of Hawaii, has been named Blue Revolution. Candidate materials for Blue Revolution were identified based on criteria of rigidity, strength, and weight. Priority was given to materials that could be used to construct lightweight VLFSs. Major static forces were considered in this preliminary analysis. The best materials were identified as those having low values of density/modulus ({rho}/E) and density/strength ({rho}/{sigma}). Concrete, metal alloys, organic-matrix composites (OMCs), and metal-matrix composites (MMCs) were evaluated. OMCs and MMCs were generally the best materials based on their very low {rho}/E and {rho}/{sigma} values.

  11. Preparation and properties of a new solid state borate ion selective electrode and its application.

    PubMed

    Somer, Güler; Sezer, Serpil; Doğan, Mehmet; Kalaycı, Sükrü; Sendil, Olcay

    2011-09-15

    A new borate ion selective electrode using solid salts of Ag(3)BO(3), Ag(2)S and Cu(2)S has been developed. Detailed information is provided concerning the composition, working pH and conditioning of the electrode. An analytically useful potential change occurred from 1×10(-6) to 1×10(-1) M borate ion. The slope of the linear portion was 31±2 mV/10-fold changes in borate concentration. The measurements were made at constant ionic strength (0.1 M NaNO(3)) and at room temperature. The effect of Cl(-), Br(-), NO(3)(-), SO(=)(4), H(2)PO(4)(-) anions and K(+), Na(+), Cu(2+), Ag(+), Ca(2+) cations on borate response is evaluated and it was found that only Ag(+) had a small interference effect. The lifetime of the electrode was more than two years, when used at least 4-5 times a day, and the response time was about 20-30s. Borate content in waste water of borax factory, tap water of a town situated near to the borax factory and city tap water far from these mines were also determined. The validation was made with differential pulse polarography for the same water sample, and high consistency was obtained. PMID:21807210

  12. Laser-based surface preparation of composite laminates leads to improved electrodes for electrical measurements

    NASA Astrophysics Data System (ADS)

    Almuhammadi, Khaled; Selvakumaran, Lakshmi; Alfano, Marco; Yang, Yang; Bera, Tushar Kanti; Lubineau, Gilles

    2015-12-01

    Electrical impedance tomography (EIT) is a low-cost, fast and effective structural health monitoring technique that can be used on carbon fiber reinforced polymers (CFRP). Electrodes are a key component of any EIT system and as such they should feature low resistivity as well as high robustness and reproducibility. Surface preparation is required prior to bonding of electrodes. Currently this task is mostly carried out by traditional sanding. However this is a time consuming procedure which can also induce damage to surface fibers and lead to spurious electrode properties. Here we propose an alternative processing technique based on the use of pulsed laser irradiation. The processing parameters that result in selective removal of the electrically insulating resin with minimum surface fiber damage are identified. A quantitative analysis of the electrical contact resistance is presented and the results are compared with those obtained using sanding.

  13. Facile Preparation and Lithium Storage Properties of TiO2 @Graphene Composite Electrodes with Low Carbon Content.

    PubMed

    Guo, Sheng-Qi; Zhen, Meng-Meng; Liu, Lu; Yuan, Zhi-Hao

    2016-08-16

    Over the past decade, TiO2 /graphene composites as electrodes for lithium ion batteries have attracted a great deal of attention for reasons of safety and environmental friendliness. However, most of the TiO2 /graphene electrodes have large graphene content (9-40 %), which is bound to increase the cost of the battery. Logically, reducing the amount of graphene is a necessary part to achieve a green battery. The synthesis of TiO2 nanosheets under solvothermal conditions without additives is now demonstrated. Through mechanical mixing TiO2 nanosheets with different amount of reduced graphene (rGO), a series of TiO2 @graphene composites was prepared with low graphene content (rGO content 1, 2, 3, and 5 wt %). When these composites were evaluated as anodes for lithium ion batteries, it was found that TiO2 +3 wt % rGO manifested excellent cycling stability and a high specific capacity (243.7 mAh g(-1) at 1 C; 1 C=167.5 mA g(-1) ), and demonstrated superior high-rate discharge/charge capability at 20 C. PMID:27339820

  14. The ternary MnFe2O4/graphene/polyaniline hybrid composite as negative electrode for supercapacitors

    NASA Astrophysics Data System (ADS)

    Sankar, Kalimuthu Vijaya; Selvan, Ramakrishnan Kalai

    2015-02-01

    The ternary MnFe2O4/graphene/polyaniline (PANI) composite was successfully prepared for the negative electrode in hybrid supercapacitors. The MnFe2O4 particles are synthesized by polymer assisted solution combustion method without any high temperature calcinations. Similarly, the flexible graphene and PANI are prepared by eco-friendly hydrothermal and in situ polymerization method, respectively. The presence of possible functional groups and the existence of individual constituents in the composite were identified through Fourier transform infra-red spectra (FT-IR) and Raman spectra. Transmission electron microscope (TEM) image reveals that the MnFe2O4 particles are dispersed on the flexible graphene sheet and are wrapped by PANI. The ternary composite electrode delivered a specific capacitance of 241 F g-1 at 0.5 mA cm-2, which was 7.5 times higher than MnFe2O4. The calculated b-value elucidates that the charge storage mechanism in the ternary system is based on the capacitive behavior rather than intercalation. The increase in ratio between capacitive and intercalation current with respect to scan rate corroborates that the pseudocapacitive charge storage mechanism is dominant. Further, the fabricated hybrid supercapacitor provides the maximum specific capacitance and energy density of 48.5 F g-1 at 0.5 mA cm-2 and 17 Wh kg-1, respectively. In addition, the hybrid supercapacitor exhibits excellent cyclic stability of up to 5000 successive cycles.

  15. Non-invasive method for selection of electrodes and stimulus parameters for FES applications with intrafascicular arrays

    NASA Astrophysics Data System (ADS)

    Dowden, B. R.; Frankel, M. A.; Normann, R. A.; Clark, G. A.

    2012-02-01

    High-channel-count intrafascicular electrode arrays provide comprehensive and selective access to the peripheral nervous system. One practical difficulty in using several electrode arrays to evoke coordinated movements in paralyzed limbs is the identification of the appropriate stimulation channels and stimulus parameters to evoke desired movements. Here we present the use of a six degree-of-freedom load cell placed under the foot of a feline to characterize the muscle activation produced by three 100-electrode Utah Slanted Electrode Arrays (USEAs) implanted into the femoral nerves, sciatic nerves, and muscular branches of the sciatic nerves of three cats. Intramuscular stimulation was used to identify the endpoint force directions produced by 15 muscles of the hind limb, and these directions were used to classify the forces produced by each intrafascicular USEA electrode as flexion or extension. For 451 USEA electrodes, stimulus intensities for threshold and saturation muscle forces were identified, and the 3D direction and linearity of the force recruitment curves were determined. Further, motor unit excitation independence for 198 electrode pairs was measured using the refractory technique. This study demonstrates the utility of 3D endpoint force monitoring as a simple and non-invasive metric for characterizing the muscle-activation properties of hundreds of implanted peripheral nerve electrodes, allowing for electrode and parameter selection for neuroprosthetic applications.

  16. Method of making sulfur tolerant composite cermet electrodes for solid oxide electrochemical cells

    DOEpatents

    Isenberg, Arnold O.

    1989-01-01

    An electrochemical apparatus is made containing an exterior electorde bonded to the exterior of a tubular, solid, oxygen ion conducting electrolyte where the electrolyte is also in contact with an interior electrode, said exterior electrode comprising particles of an electronic conductor contacting the electrolyte, where a ceramic metal oxide coating partially surrounds the particles and is bonded to the electrolyte, and where a coating of an ionic-electronic conductive material is attached to the ceramic metal oxide coating and to the exposed portions of the particles.

  17. Electrochemical degradation of carbamazepine using modified electrode with graphene-AuAg composite

    NASA Astrophysics Data System (ADS)

    Pogacean, F.; Biris, A. R.; Socaci, C.; Floare-Avram, V.; Rosu, M. C.; Coros, M.; Pruneanu, S.

    2015-12-01

    Carbamazepine is a pharmaceutical drug which has been detected in surface and drinking water primarily due to human usage but also from the accidental disposal of pharmaceuticals into sewers. We have developed a graphene-modified electrode which was tested at the detection and degradation of carbamazepine. The oxidation process was studied by cyclic voltammetry in aqueous and organic solutions. The electrochemical degradation of carbamazepine was performed by polarizing the working electrode at a certain potential, for different times (from 5 to 60 minutes). The degradation efficiency was highly dependent on the type of solution and on the supporting electrolyte.

  18. Development, characterization and applications of electrodes modified with conductive polymers, ionic liquids and proteins

    NASA Astrophysics Data System (ADS)

    Tang, Yijun

    My research involves both fundamental studies and applications of the electrodes whose surfaces are chemically modified. Conductive polymers are one of the major materials that are used to modify electrode surfaces. The thorough understanding of the behavior of conductive polymers in ionic liquids is interesting and important as the ionic liquids are becoming promising solvents. With poly(vinyl ferrocene) as the model conductive polymer, electrochemical studies were performed in various ionic liquid electrolytes. A theoretical square model and dynamic equilibrium were proposed to describe the interaction between conductive polymers and ionic liquids when the electrons transferred between the electrode and electrolyte. These findings were applied to enable and accelerate the structure relaxation of conductive polymers so that the conductive polymers were capable of delivering peptides efficiently. Incorporation of metallic nanoparticles to the conductive polymer matrix entitled new properties to the conductive polymer, increasing conductivity and providing catalytic abilities. This modification on electrode surface might bring potential uses in gas sensing, energy storage, energy conversion, etc. Conductive polymer coated electrodes produced unique double layer in ionic liquids and a fundamental study of quantum charging help to understand the double layer properties. I also studied the application of surface modified electrodes in chemo- and biosensing. A nonregeneration protocol was created to save the cost and the time in analyzing interfacial binding activities and to prevent the potential of deterioration caused to biological ligands by the conventional regeneration. In the study of carbohydrate/protein interactions, a "click" chemical reaction was first used in constructing a carbohydrate-based biosensor, which was capable of detecting and analyzing proteins specifically and accurately. In another biosensor design, the hydrogen bonding between the template and

  19. Electrolyte incorporation into composite electrodes for proton-exchange membrane fuel cells and lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Oh, Jung Min

    2011-12-01

    This dissertation describes research on the preparation and characterization of composite electrodes for use in proton-exchange membrane (PEM) fuel cells and lithium ion batteries. The general focus of the research was on high-surface-area carbon supports for platinum catalysts in fuel cells, and integration of electrolytes, particularly fluoropolymer electrolytes, into composite electrodes both batteries and fuel cells. Results are described for work in the following three specific topical areas. (1) Carbon nanofibers for use as platinum (Pt) catalyst supports in fuel cells were prepared by carbonization of electrospun acrylic fibers. The resulting carbon nanofibers were found to contain mainly micropores. Following grinding to a powder form, the carbon nanofibers were used as supports for Pt nanoparticles. The pulverized carbon nanofibers were found to be not suitable as supports for Pt catalysts because the microporosity of the individual carbon nanofibers cannot provide continuous porous channels in the electrode. As a result, the Pt utilization was found to be low. (2) Mesoporous carbon composites containing nanoscale embedded zirconia particles (ZCS) were prepared and found to be highly porous and electrically conductive. Surface modification of the composites with organic compounds having phenylphosphonic acid groups (e.g., phenylphosphonic acid, m-sulfophenylphosphonic acid, or sulfonated fluoropolymer ionomer having terminal phosphonic acid groups) was accomplished by simple exposure of the carbon composite to organophosphonate solutions. Nanoscale ZrO2 surfaces present in the composite skeleton acted as reactive sites for anchoring of phosphonates through formation of robust Zr--O--P bonding. Proton-exchange sites were introduced onto the nanocomposite surface by grafting m-sulfophenylphosphonic acid or a sulfonated fluoropolymer ionomer. Modification with the ionomer provided an increase in proton-exchange capacity relative to that found following

  20. (Metal-Organic Framework)-Polyaniline sandwich structure composites as novel hybrid electrode materials for high-performance supercapacitor

    NASA Astrophysics Data System (ADS)

    Guo, ShuaiNan; Zhu, Yong; Yan, YunYun; Min, YuLin; Fan, JinChen; Xu, QunJie; Yun, Hong

    2016-06-01

    Carbonized Zn-(Metal-Organic Framework)MOF- polyaniline composites for high performance of supercapacitor have been developed from zinc acetate, 8-Hydroxyquinoline, and aniline via a simple process. The as-synthesized product has been characterized by X-ray powder diffraction (XRD), Scanning electron microscopy(SEM), Fourier transform infrared spectra (FT-IR), Transmission electron microscope (TEM). The electrochemical properties of carbonized Zn-MOF/polyaniline electrode were investigated by current charge-discharge and cyclic voltammetry. The specific capacitance of MOF/PANI has been approach to be as high as 477 F g-1 at a current density of 1 A g-1.

  1. Chemically and compositionally modified solid solution disordered multiphase nickel hydroxide positive electrode for alkaline rechargeable electrochemical cells

    DOEpatents

    Ovshinsky, Stanford R.; Corrigan, Dennis; Venkatesan, Srini; Young, Rosa; Fierro, Christian; Fetcenko, Michael A.

    1994-01-01

    A high capacity, long cycle life positive electrode for use in an alkaline rechargeable electrochemical cell comprising: a solid solution nickel hydroxide material having a multiphase structure that comprises at least one polycrystalline .gamma.-phase including a polycrystalline .gamma.-phase unit cell comprising spacedly disposed plates with at least one chemical modifier incorporated around the plates, the plates having a range of stable intersheet distances corresponding to a 2.sup.+ oxidation state and a 3.5.sup.+, or greater, oxidation state; and at least one compositional modifier incorporated into the solid solution nickel hydroxide material to promote the multiphase structure.

  2. Sol-gel-derived composite antimony-doped, tin oxide-coated clay-silicate semitransparent and conductive electrodes.

    PubMed

    Sadeh, A; Sladkevich, S; Gelman, F; Prikhodchenko, P; Baumberg, I; Berezin, O; Lev, O

    2007-07-15

    A new form of conductive and transparent porous composite electrode is introduced. The electrode material is composed of antimony-doped, tin oxide (ATO)-coated mica platelets imbedded in sol-gel-derived silicate or methyl silicate network. The platelet clays self-align in a layered structure within the silicate film, an anisotropic construction that minimizes the ATO loading required to achieve electric percolation. Transparency and resistance as a function of clay loading is reported with typical values of 100 k Omega/square and 1.5 OD for a 20-microm-thick film. The transparency is lower as compared to sputtered ATO glasses, but this is, as far as we know, the best method for the low-temperature preparation of transparent, porous, and electrically conductive (as opposed to the amply reported ionically conductive) electrode materials. Permselectivity induced by the silicate and clay ingredients is demonstrated by permeation of positively charged methyl viologen compared to negatively charged ferricyanide. Prussian blue-modified ATO-coated platelets dispersed in sol-gel-derived silicate were used to demonstrate feasibility of a transparent and electrically conductive porous electrochromic material. PMID:17555295

  3. The Development of Nano-Composite Electrodes for Solid Oxide Electrolyzers

    SciTech Connect

    Gorte, Raymond J.; Vohs, John M.

    2014-03-26

    Solid oxide fuel cells (SOFC) and electrolyzers (SOE) offer an attractive means for converting between electrical and chemical energy. Because they operate at high temperatures and are usually based on electrolytes that are oxygen-ion conducting ceramics, such as yttria-stabilized zirconia (YSZ), they are equally capable of converting between CO and CO2 as between H2 and H2O. When operated in the SOFC mode, they are able to operate on hydrocarbon fuels so long as there are no materials within the anode that can catalyze carbon formation. Compared to other types of electrolyzers, SOE can exhibit the highest efficiencies because the theoretical Nernst potential is lower at high temperatures and because the electrode overpotentials in SOE tend to be much lower. Finally, pure H2 can be produced without an external electrical source by electrolysis of steam at one electrode and oxidation of any fuel at the other electrode through a process known as Natural-Gas Assisted Steam Electrolysis. This final report describes results from studies of novel electrodes for SOE and SOFC prepared by infiltration methods.

  4. Influence of electrode preparation on the electrochemical performance of LiNi0.8Co0.15Al0.05O2 composite electrodes for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Tran, Hai Yen; Greco, Giorgia; Täubert, Corina; Wohlfahrt-Mehrens, Margret; Haselrieder, Wolfgang; Kwade, Arno

    2012-07-01

    The electrode manufacturing for lithium-ion batteries is based on a complex process chain with several influencing factors. A proper tailoring of the electrodes can greatly improve both the electrochemical performances and the energy density of the battery. In the present work, some significant parameters during the preparation of LiNi0.8Co0.15Al0.05O2-based cathodes were investigated. The active material was mixed with a PVDF-binder and two conductive additives in different ratios. The electrode thickness, the degree of compacting and the conductive agent type and mixing ratio have proven to have a strong impact on the electrochemical performances of the composite electrodes, especially on their behaviour at high C-rates. Further it has been shown that the compacting has an essential influence on the mechanical properties of NCA coatings, according to their total, ductile and elastic deformation behaviour.

  5. Polymer light harvesting composites for optoelectronic applications

    NASA Astrophysics Data System (ADS)

    Sun, Sam-Shajing; Wang, Dan

    2015-09-01

    Polymer based optoelectronic composites and thin film devices exhibit great potential in space applications due to their lightweight, flexible shape, high photon absorption coefficients, and robust radiation tolerance in space environment. Polymer/dye composites appear promising for optoelectronics applications due to potential enhancements in both light harvesting and charge separation. In this study, the optoelectronic properties of a series of molecular dyes paired with a conjugated polymer Poly(3-hexylthiophene-2,5-diyl) (P3HT) were investigated. Specifically, the solution PL quenching coefficients (Ksv) of dye/polymer follows a descending order from dyes of Chloro(protoporphyrinato)iron(III) (Hemin), Protoporphyrin, to meso-Tetra(4-carboxyphenyl)porphine (TCPP). In optoelectronic devices made of the P3HT/dye/PCBM composites, the short circuit current densities Jsc as well as the overall power conversion efficiencies (PCE) also follow a descending order from Hemin, Protoporphyrin, to TCPP, despite Hemin exhibits the intermediate polymer/dye LUMO (lowest unoccupied molecular orbital) offset and lowest absorption coefficient as compared to the other two dyes, i.e., the cell optoelectronic efficiency did not follow the LUMO offsets which are the key driving forces for the photo induced charge separations. This study reveals that too large LUMO offset or electron transfer driving force may result in smaller PL quenching and optoelectronic conversion efficiency, this could be another experimental evidence for the Marcus electron transfer model, particularly for the Marcus `inverted region'. It appears an optimum electron transfer driving force or strong PL quenching appears more critical than absorption coefficient for optoelectronic conversion devices.

  6. 1-3 piezoelectric composites for high temperature transducer applications

    PubMed Central

    Li, Lili; Zhang, Shujun; Xu, Zhuo; Wen, Fei; Geng, Xuecang; Lee, Hyeong Jae; Shrout, Thomas R.

    2013-01-01

    High temperature Pb(Zr,Ti)O3 /epoxy 1-3 composites were fabricated using the dice and fill method. The epoxy filler was modified with glass spheres in order to improve the thermal reliability of the composites at elevated temperatures. Temperature dependent dielectric and electromechanical properties of the composites were measured after aging at 250°C with different dwelling times. Obvious cracks were observed and the electrodes were damaged in the composite with unmodified epoxy after 200 hours, leading to the failure of the composite. In contrast, composites with >12 vol% glass sphere loaded epoxies were found to exhibit minimal electrical property variation after aging for 500 hours, with dielectric permittivity, piezoelectric coefficient and electromechanical coupling being on the order of 940, 310pC/N and 57%, respectively. This is due to the improved thermal expansion behavior of the modified filler. PMID:23729863

  7. Applicator and electrode design for in vivo DNA delivery by electroporation.

    PubMed

    Rabussay, Dietmar

    2008-01-01

    As in vivo electroporation advances from the preclinical phase to clinical studies and eventually to routine medical practice, the design of electroporation devices becomes increasingly important. Achieving safety and efficacy levels that meet regulatory requirements, as well as user and patient friendliness, are major design considerations. In addition, the devices will have to be economical to manufacture. This chapter will focus on the design of applicators and electrodes, the pieces of hardware in direct contact with the user and the patient, and thus key elements responsible for the safety and efficacy of the procedure. The two major foreseeable applications of the technology in the DNA field are for gene therapy and DNA vaccination. Design requirements differ considerably for these applications and for the diseases to be treated or prevented. In addition to the trend of device differentiation, there is also a trend to build devices capable of performing both the step of delivering the DNA to the target tissue and the subsequent step of electroporation. This chapter presents the electrical and biological principles underlying applicator and electrode design, gives an overview of existing devices, and discusses their advantages and disadvantages. The chapter also outlines major design considerations, including regulatory pathways, and points out potential future developments. PMID:18370189

  8. Nanostructured metal-polyaniline composites and applications thereof

    DOEpatents

    Wang, Hsing-Lin; Li, Wenguang; Bailey, James A.; Gao, Yuan

    2012-10-02

    Metal-polyaniline (PANI) composites are provided together with a process of preparing such composites by an electrodeless process. The metal of the composite can have nanoscale structural features and the composites can be used in applications such as catalysis for hydrogenation reactions and for analytical detection methods employing SERS.

  9. Ordered mesoporous carbon/graphene nano-sheets composites as counter electrodes in dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Shao, Leng-Leng; Chen, Ming; Ren, Tie-Zhen; Yuan, Zhong-Yong

    2015-01-01

    The composites of ordered mesoporous carbon (OMC) and graphene nano-sheets (GNS) are prepared by mixing OMC with different weight ratios of GNS, and utilized as counter electrode (CE) materials for dye-sensitized solar cells (DSSCs). Electrochemical impedance spectroscopy, Tafel polarization, and cyclic voltammetry measurements demonstrate that the OMC/GNS CEs display the enhanced electron transport property and fast reduction rate of I3- in comparison with those of the individual OMC and GNS CEs, due to the combination of superior electrical conductivity of GNS and good catalytic activity of OMC. Under AM 1.5 irradiation (100 mW cm-2), the DSSCs based on the OMC/GNS CEs show a maximum power conversion efficiency of 6.82%, which is comparable to 7.08% of the cell with the conventional Pt CE at the same experimental conditions, suggesting that the OMC/GNS composites are one of advanced CE materials for low-cost DSSCs.

  10. Electrospun composite nanofibers of poly vinyl pyrrolidone and zinc oxide nanoparticles modified carbon paste electrode for electrochemical detection of curcumin.

    PubMed

    Afzali, Moslem; Mostafavi, Ali; Shamspur, Tayebeh

    2016-11-01

    A simple and novel ferrocene-nanofiber carbon paste electrode was developed to determine curcumin in a phosphate buffer solution at pH=8. ZnO nanoparticles were produced via a sonochemical process and composite nanofibers of PVP/ZnO were prepared by electrospinning. The characterization was performed by SEM, XRD and IR. The results suggest that the electrospun composite nanofibers having a large surface area promote electron transfer for the oxidation of curcumin and hence the FCNFCPE exhibits high electrocatalytic activity and performs well in regard to the oxidation of curcumin. The proposed method was successfully applied for measurement of curcumin in urine and turmeric as real samples. PMID:27524081

  11. The application of phase contrast X-ray techniques for imaging Li-ion battery electrodes

    NASA Astrophysics Data System (ADS)

    Eastwood, D. S.; Bradley, R. S.; Tariq, F.; Cooper, S. J.; Taiwo, O. O.; Gelb, J.; Merkle, A.; Brett, D. J. L.; Brandon, N. P.; Withers, P. J.; Lee, P. D.; Shearing, P. R.

    2014-04-01

    In order to accelerate the commercialization of fuel cells and batteries across a range of applications, an understanding of the mechanisms by which they age and degrade at the microstructural level is required. Here, the most widely commercialized Li-ion batteries based on porous graphite based electrodes which de/intercalate Li+ ions during charge/discharge are studied by two phase contrast enhanced X-ray imaging modes, namely in-line phase contrast and Zernike phase contrast at the micro (synchrotron) and nano (laboratory X-ray microscope) level, respectively. The rate of charge cycling is directly dependent on the nature of the electrode microstructure, which are typically complex multi-scale 3D geometries with significant microstructural heterogeneities. We have been able to characterise the porosity and the tortuosity by micro-CT as well as the morphology of 5 individual graphite particles by nano-tomography finding that while their volume varied significantly their sphericity was surprisingly similar. The volume specific surface areas of the individual grains measured by nano-CT are significantly larger than the total volume specific surface area of the electrode from the micro-CT imaging, which can be attributed to the greater particle surface area visible at higher resolution.

  12. Metal-organic frameworks and β-cyclodextrin-based composite electrode for simultaneous quantification of guanine and adenine in a lab-on-valve manifold.

    PubMed

    Wang, Yang; Chen, Huanhuan; Wu, Yichun; Ge, Huali; Ye, Guiqin; Hu, Xiaoya

    2014-12-01

    In this work, a novel chemically modified electrode is constructed based on metal-organic frameworks and β-cyclodextrin (Cu3(BTC)2/β-CD, BTC = benzene-1,3,5-tricarboxylate) composite material. The electrode was used for simultaneous determination of guanine and adenine in a sequential injection lab-on-valve format and exhibited sensitive responses to guanine and adenine oxidation due to the π-π stacking interaction of Cu3(BTC)2 and the inclusion behavior of β-CD. The analytical performance was assessed with respect to the supporting electrolyte and its pH, accumulation time and accumulation potential, and the fluid flow rates. Under optimal conditions, linear calibration ranges for both guanine and adenine were from 1.0 × 10(-7) to 1.0 × 10(-5) mol L(-1), and detection limits (S/N = 3) were found to be 5.2 × 10(-8) and 2.8 × 10(-8) mol L(-1), respectively. The proposed sensor showed advantages of high sensitivity, simple sample preparation protocol, enhanced throughput and good reproducibility. Finally, the practical application of the proposed sensor has been performed for the determination of guanine and adenine in real samples with satisfactory results. PMID:25299249

  13. Electrodes for high-definition transcutaneous DC stimulation for applications in drug-delivery and electrotherapy, including tDCS

    PubMed Central

    Minhas, Preet; Bansal, Varun; Patel, Jinal; Ho, Johnson S.; Diaz, Julian; Datta, Abhishek; Bikson, Marom

    2010-01-01

    Transcutaneous electrical stimulation is applied in a range of biomedical applications including Transcranial Direct Current Stimulation (tDCS). tDCS is a non-invasive procedure where a weak direct current (<2 mA) is applied across the scalp to modulate brain function. High-Definition tDCS (HD-tDCS) is a technique used to increase the spatial focality of tDCS by passing current across the scalp using <12 mm diameter electrodes. The purpose of this study was to design and optimize “high-definition” electrode-gel parameters for electrode durability, skin safety, and subjective pain. Anode and cathode electrode potential, temperature, pH, and subjective sensation over time were assessed during application of 2 mA direct current, for up to 22 minutes on agar gel or subject forearms. A selection of 5 types of solid-conductors (Ag pellet, Ag/AgCl pellet, Rubber pellet, Ag/AgCl ring, and Ag/AgCl disc) and 7 conductive gels (Signa, Spectra, Tensive, Redux, BioGel, Lectron, and CCNY-4) were investigated. The Ag/AgCl ring in combination with CCNY-4 gel resulted in the most favorable outcomes. Under anode stimulations, electrode potential and temperature rises were generally observed in all electrode-gel combinations except for Ag/AgCl ring and disc electrodes. pH remained constant for all solid-conductors except for both Ag and Rubber pellet electrodes with Signa and CCNY-4 gels. Sensation ratings were independent of stimulation polarity. Ag/AgCl ring electrodes were found to be the most comfortable followed by Ag, Rubber, and Ag/AgCl pellet electrodes across all gels. PMID:20488204

  14. An investigation of the work function of metal gate electrodes for advanced CMOS applications

    NASA Astrophysics Data System (ADS)

    Wong, Gloria Man Ting

    Scaling the gate length and oxide thickness of the metal oxide semiconductor field effect transistor (MOSFET) offers great potential to improve device performance and circuit density. The use of metals for the gate electrode eliminates problems associated with conventional polycrystalline silicon, and shows better compatibility with high-k gate dielectrics. In order to optimize transistor performance, metals with appropriate work functions for both NMOS and PMOS must be identified and integrated into the conventional CMOS process flow. In this work, both single metal and two-component metal gate systems were investigated to develop a fundamental understanding of the factors that influence the metal gate electrode work function. The work function of tungsten was found to be higher in evaporated electrodes than in sputter-deposited films, which may be related to differences in roughness, density, grain size and as-grown oxygen content observed by physical characterization. In the two-component systems, metal gates were fabricated using a stacked bilayer structure. In previous work, it was found that the work function can be controlled by the thickness of the underlayer metal (the layer closest to the oxide). Depending on the amount of diffusion, the influence of the overlayer on the atomic concentration at the dielectric interface varies. Three two-component systems were investigated: Nb-W, Ti-W and Pt-Ti. By selecting materials systems that exhibit differences in diffusion and phase formation (as predicted by their phase diagrams), the change in work function due to underlayer thickness and composition for all three metal pairs is elucidated. The diffusion behavior in bilayer metal gates was investigated using x-ray reflectivity of multilayer films and was also modeled to quantify the differences between these three metal-metal systems. The effect of composition on the work function was directly probed by fabricating alloy metal gate electrodes by co-sputtering. A

  15. Fabrication of Pt nanoparticles-decorated CVD diamond electrode for biosensor applications.

    PubMed

    Song, Min-Jung; Kim, Jong-Hoon; Lee, Seung-Koo; Lim, Dae-Soon

    2011-01-01

    An electrochemical biosensor was developed using boron-doped diamond (BDD) as an electrode material. To enhance the electrical performance of the electrode, the BDD electrode was decorated with Pt-nanoparticles (Pt-NPs) by electrochemical deposition. Their morphology according to the applied potentials for the synthesis of Pt-NPs was characterized by SEM. To identify the performance of the electrode modified with Pt-NPs, glucose detection was used as a sample sensing process, and the results were compared with those of a gold electrode and a bare BDD electrode. The electrochemical characteristics of the modified electrode were examined by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The BDD electrode with the Pt-NPs showed higher sensitivity and a lower detection limit than the Au electrode and BDD electrode. The proposed biosensor based on the Pt-NPs decorated BDD electrode showed high sensitivity, a low detection limit, fast direct electron transfer and good stability. PMID:21985922

  16. High-performance binder-free supercapacitor electrode by direct growth of cobalt-manganese composite oxide nansostructures on nickel foam

    PubMed Central

    2014-01-01

    A facile approach composed of hydrothermal process and annealing treatment is proposed to directly grow cobalt-manganese composite oxide ((Co,Mn)3O4) nanostructures on three-dimensional (3D) conductive nickel (Ni) foam for a supercapacitor electrode. The as-fabricated porous electrode exhibits excellent rate capability and high specific capacitance of 840.2 F g-1 at the current density of 10 A g-1, and the electrode also shows excellent cycling performance, which retains 102% of its initial discharge capacitance after 7,000 cycles. The fabricated binder-free hierarchical composite electrode with superior electrochemical performance is a promising candidate for high-performance supercapacitors. PMID:25258611

  17. Effects of activated carbon characteristics on the electrosorption capacity of titanium dioxide/activated carbon composite electrode materials prepared by a microwave-assisted ionothermal synthesis method.

    PubMed

    Liu, Po-I; Chung, Li-Ching; Ho, Chia-Hua; Shao, Hsin; Liang, Teh-Ming; Horng, Ren-Yang; Chang, Min-Chao; Ma, Chen-Chi M

    2015-05-15

    Titanium dioxide (TiO2)/ activated carbon (AC) composite materials, as capacitive deionization electrodes, were prepared by a two-step microwave-assisted ionothermal synthesis method. The electrosorption capacity of the composite electrodes was studied and the effects of AC characteristics were explored. These effects were investigated by multiple analytical techniques, including X-ray photoelectron spectroscopy, thermogravimetry analysis and electrochemical impedance spectroscopy, etc. The experimental results indicated that the electrosorption capacity of the TiO2/AC composite electrode is dependent on the characteristics of AC including the pore structure and the surface property. An enhancement in electrosorption capacity was observed for the TiO2/AC composite electrode prepared from the AC with higher mesopore content and less hydrophilic surface. This enhancement is due to the deposition of anatase TiO2 with suitable amount of Ti-OH. On the other hand, a decline in electrosorption capacity was observed for the TiO2/AC composite electrode prepared from the AC with higher micropore content and highly hydrophilic surface. High content of hydrogen bond complex formed between the functional group on hydrophilic surface with H2O, which will slow down the TiO2 precursor-H2O reaction. In such situation, the effect of TiO2 becomes unfavorable as the loading amount of TiO2 is less and the micropore can also be blocked. PMID:25576198

  18. Preparation of novel mercury-doped silver nanoparticles film glassy carbon electrode and its application for electrochemical biosensor.

    PubMed

    Li, Mao-Guo; Shang, Yong-Jia; Gao, Ying-Chun; Wang, Guang-Feng; Fang, Bin

    2005-06-01

    A novel mercury-doped silver nanoparticles film glassy carbon (Ag/MFGC) electrode was prepared in this study. Electrochemical behaviors of cysteine on the Ag/MFGC electrode were investigated by electrochemical impedance spectroscopy and cyclic voltammetry (CV). The results indicated that cysteine could be strongly adsorbed on the surface of the Ag/MFGC electrode to form a thin layer. The doped electrode could catalyze the electrode reaction process of cysteine, and the cysteine displayed a pair of well-defined and nearly reversible CV peaks at the electrode in an acetate buffer solution (pH 5.0). The Ag/MFGC electrode was used for determination of cysteine by differential pulse voltammetry. The linear range was between 4.0x10(-7) and 1.3x10(-5) mol/L, with a detection limit of 1.0x10(-7) mol/L and a signal-to-noise ratio of 3. The relative standard deviation was 2.4% for seven successive determinations of 1.0x10(-5) mol/L cysteine. The determinations of cysteine in synthetic samples and urinal samples were carried out and satisfactory results were obtained. Amperometric application of the Ag/MFGC electrode as biosensors is proposed. PMID:15866527

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

    PubMed

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

    2006-11-01

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

  20. Sensitive voltammetric determination of vanillin with an AuPd nanoparticles-graphene composite modified electrode.

    PubMed

    Shang, Lei; Zhao, Faqiong; Zeng, Baizhao

    2014-05-15

    In this work, graphene oxide was reduced to graphene with an endogenous reducing agent from dimethylformamide, and then AuPd alloy nanoparticles were electrodeposited on the graphene film. The obtained AuPd-graphene hybrid film was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and voltammetry. The electrochemical behavior of vanillin was studied using the AuPd-graphene hybrid based electrode. It presented high electrocatalytic activity and vanillin could produce a sensitive oxidation peak at it. Under the optimal conditions, the peak current was linear to the concentration of vanillin in the ranges of 0.1-7 and 10-40 μM. The sensitivities were 1.60 and 0.170 mA mM(-1) cm(-2), respectively; the detection limit was 20 nM. The electrode was successfully applied to the detection of vanillin in vanilla bean, vanilla tea and biscuit samples. PMID:24423501

  1. Characterization of peptide-nanostructure-modified electrodes and their application for ultrasensitive environmental monitoring.

    PubMed

    Adler-Abramovich, Lihi; Badihi-Mossberg, Michal; Gazit, Ehud; Rishpon, Judith

    2010-04-01

    Dense arrays of self-assembled nanostructures are highly important for the fabrication of high-performance sensors of large surface area. The organized incorporation of novel biocompatible organic nanostructures into extremely sensitive amperometric biosensors is demonstrated. Peptide nanoforest biosensors for phenol detection were 17-fold more sensitive than uncoated electrode and more sensitive than those modified with carbon nanotubes or combined coating. The high sensitivity reported, together with the biocompatibility and the ability to chemically and biologically modify these elements, may provide a novel platform for biosensors design and fabrication for environmental monitoring, homeland security, and other applications. PMID:20205204

  2. Electrically and mechanically enhanced Ag nanowires-colorless polyimide composite electrode for flexible capacitive sensor

    NASA Astrophysics Data System (ADS)

    Kim, Dae-Gon; Kim, Jiwan; Jung, Seung-Boo; Kim, Young-Sung; Kim, Jong-Woong

    2016-09-01

    Silver nanowire (AgNW) network is known for its low percolation threshold, high conductivity and good flexibility, therefore, considered one of the best candidates for fabrication of flexible and transparent electrodes. However, a general approach to make the AgNWs-based electrodes, an overcoating of nanowire dispersion onto a transparent polymer, should make an issue of poor mechanical stability, mainly caused by low adhesion between the nanowires and polymer. In addition, a thin insulating layer of polyvinylpyrrolidone (PVP) formed on the surface of AgNWs deteriorates the conductivity of their network, which means that a post-processing such as high temperature annealing is essentially needed. Here we employed a plasma treatment with an inert gas to remove the residual PVP layer, so that the conductivity could be enhanced without employing any high temperature processing. Interestingly, the optical transmittance in the wavelength near 400 nm was also increased, resulting in more neutral coloration of the electrode. An inverted layer processing made the nanowires to be partially buried at the surface of colorless polyimide (cPI), so that the enhancement of mechanical stability and connectivity with overlying materials were simultaneously achieved.

  3. Nickel Nanofoam/Different Phases of Ordered Mesoporous Carbon Composite Electrodes for Superior Capacitive Energy Storage.

    PubMed

    Lee, Kangsuk; Song, Haeni; Lee, Kwang Hoon; Choi, Soo Hyung; Jang, Jong Hyun; Char, Kookheon; Son, Jeong Gon

    2016-08-31

    Electrochemical energy storage devices based on electric double layer capacitors (EDLCs) have received considerable attention due to their high power density and potential for obtaining improved energy density in comparison to the lithium ion battery. Ordered mesoporous carbon (OMC) is a promising candidate for use as an EDLC electrode because it has a high specific surface area (SSA), providing a wider charge storage space and size-controllable mesopore structure with a long-range order, suppling high accessibility to the electrolyte ions. However, OMCs fabricated using conventional methods have several drawbacks including low electronic conductivity and long ionic diffusion paths in mesopores. We used nickel nanofoam, which has a relatively small pore (sub-100 nm to subμm) network structure, as a current collector. This provides a significantly shortened electronic/ionic current paths and plentiful surface area, enabling stable and close attachment of OMCs without the use of binders. Thus, we present hierarchical binder-free electrode structures based on OMC/Ni nanofoams. These structures give rise to enhanced specific capacitance and a superior rate capability. We also investigated the mesopore structural effect of OMCs on electrolyte transport by comparing the capacitive performances of collapsed lamellar, cylindrical, and spherical mesopore electrodes. The highly ordered and straightly aligned cylindrical OMCs exhibited the highest specific capacitance and the best rate capability. PMID:27490161

  4. Application of Composite Mechanics to Composites Enhanced Concrete Structures

    NASA Technical Reports Server (NTRS)

    Chamis, Christos C.; Gotsis, Pascal K.

    2006-01-01

    A new and effective method is described to design composites to repair damage or enhance the overload strength of concrete infrastructures. The method is based on composite mechanics which is available in computer codes. It is used to simulate structural sections made from reinforced concrete which are typical in infrastructure as well as select reinforced concrete structures. The structural sections are represented by a number of layers through the thickness where different layers are used in concrete, and for the composite. The reinforced concrete structures are represented with finite elements where the element stiffness parameters are from the structural sections which are represented by composite mechanics. The load carrying capability of the structure is determined by progressive structural fracture. Results show up to 40 percent improvements for damage and for overload enhancement with relatively small laminate thickness for the structural sections and up to three times for the composite enhanced select structures (arches and domes).

  5. Well-defined flake-like polypyrrole grafted graphene nanosheets composites as electrode materials for supercapacitors with enhanced cycling stability

    NASA Astrophysics Data System (ADS)

    Wang, Xue; Wang, Tingmei; Yang, Chao; Li, Haidong; Liu, Peng

    2013-12-01

    Well-defined flake-like polypyrrole grafted graphene nanosheets composites (PPy-g-GNS) were fabricated by the in-situ chemical oxidative grafting polymerization of pyrrole in the presence of the 4-aminophenyl modified graphene nanosheets (AP-GNS), which were prepared via the coupling reaction of the graphene nanosheets (GNS) with diazonium salt. The flake-like PPy-g-GNS composite showed the high conductivity at room temperature. A maximum discharge capacitance of 191.2 F/g at the scan rate of 10 mV/s could be achieved in the three-electrode cell electrochemical testing in 1.0 mol/L NaNO3 electrolyte solution. It is higher than those of the AP-GNS, pure PPy, and the GNS/PPy composite prepared with the unmodified graphene nanosheets (GNS). The flake-like PPy-g-GNS composites also exhibited the excellent electrochemical stability even after 1000 cycles. It revealed the synergistic effect between the conducting polymer and the carbon-based support.

  6. Synthesis of honeycomb MnO2 nanospheres/carbon nanoparticles/graphene composites as electrode materials for supercapacitors

    NASA Astrophysics Data System (ADS)

    Xiong, Yachao; Zhou, Min; Chen, Hao; Feng, Lei; Wang, Zhao; Yan, Xinzhu; Guan, Shiyou

    2015-12-01

    Improving the electrochemical performance of manganese dioxide (MnO2) electrodes is of great significance for supercapacitors. In this study, a novel honeycomb MnO2 nanospheres/carbon nanoparticles/graphene composites has been fabricated through freeze-drying method. The honeycomb MnO2 nanospheres are well inserted and dispersed on the graphene. Carbon nanoparticles in the composites act as spacers to effectively prevent graphene from restacking and agglomeration, construct efficient 3D conducting architecture with graphene for honeycomb MnO2 nanospheres, and alleviate the aggregation of honeycomb MnO2 nanospheres by separating them from each other. As a result, such honeycomb MnO2 nanospheres/carbon nanoparticles/graphene composites display much improved electrochemical capacitive performance of 255 F g-1 at a current density of 0.5 A g-1, outstanding rate capability (150 F g-1 remained at a current density of 20 A g-1) and good cycling stability (83% of the initial capacitance retained after 1000 charge/discharge cycles). The strategy for the synthesis of these composites is very effective.

  7. A sensitive determination of terbutaline in pharmaceuticals and urine samples using a composite electrode based on zirconium oxide nanoparticles.

    PubMed

    Baytak, Aysegul Kutluay; Teker, Tugce; Duzmen, Sehriban; Aslanoglu, Mehmet

    2016-10-01

    An accurate and precise determination of terbutaline has been carried out using a glassy carbon electrode (GCE) modified with a composite of multi-walled carbon nanotubes (MWCNTs) and nanoparticles of zirconium oxide (ZrO2NPs). Energy dispersive X-ray and scanning electron microscopic techniques were utilized for the characterization of the composite layer. Terbutaline exhibited a broad oxidation peak at 770mV on a GCE. However, MWCNTs/GCE presented an electrocatalytic effect toward the oxidation of terbutaline with a better anodic peak at 660mV. Furthermore, the electrochemical behavior of terbutaline has greatly been improved at a GCE modified with a composite of MWCNTs and nanoparticles of ZrO2. The ZrO2NPs/MWCNTs/GCE exhibited a sharp anodic wave at 645mV with a large enhancement of the current response for terbutaline. Square wave voltammetry (SWV) was performed for the determination of terbutaline at ZrO2NPs/MWCNTs/GCE. A linear plot was obtained for the current responses of terbutaline against concentrations in the range of 10-160nM yielding a detection limit of 2.25nM (based on 3Sb/m). Improved voltammetric behavior, long-time stability and good reproducibility were obtained for terbutaline at the proposed electrode. A mean recovery of 101.2% with an RSD% of 1.9 was obtained for the analysis of the drug formulation. The accurate and precise quantification of terbutaline makes the ZrO2NPs/MWCNTs/GCE system of great interest for monitoring its therapeutic use. PMID:27287106

  8. Healable capacitive touch screen sensors based on transparent composite electrodes comprising silver nanowires and a furan/maleimide diels-alder cycloaddition polymer.

    PubMed

    Li, Junpeng; Liang, Jiajie; Li, Lu; Ren, Fengbo; Hu, Wei; Li, Juan; Qi, Shuhua; Pei, Qibing

    2014-12-23

    A healable transparent capacitive touch screen sensor has been fabricated based on a healable silver nanowire-polymer composite electrode. The composite electrode features a layer of silver nanowire percolation network embedded into the surface layer of a polymer substrate comprising an ultrathin soldering polymer layer to confine the nanowires to the surface of a healable Diels-Alder cycloaddition copolymer and to attain low contact resistance between the nanowires. The composite electrode has a figure-of-merit sheet resistance of 18 Ω/sq with 80% transmittance at 550 nm. A surface crack cut on the conductive surface with 18 Ω is healed by heating at 100 °C, and the sheet resistance recovers to 21 Ω in 6 min. A healable touch screen sensor with an array of 8×8 capacitive sensing points is prepared by stacking two composite films patterned with 8 rows and 8 columns of coupling electrodes at 90° angle. After deliberate damage, the coupling electrodes recover touch sensing function upon heating at 80 °C for 30 s. A capacitive touch screen based on Arduino is demonstrated capable of performing quick recovery from malfunction caused by a razor blade cutting. After four cycles of cutting and healing, the sensor array remains functional. PMID:25486240

  9. Electrocatalytic activity of NiO on silicon nanowires with a carbon shell and its application in dye-sensitized solar cell counter electrodes

    NASA Astrophysics Data System (ADS)

    Kim, Junhee; Jung, Cho-Long; Kim, Minsoo; Kim, Soomin; Kang, Yoonmook; Lee, Hae-Seok; Park, Jeounghee; Jun, Yongseok; Kim, Donghwan

    2016-03-01

    To improve the catalytic activity of a material, it is critical to maximize the effective surface area by directly contacting the electrolyte. Nanowires are a promising building block for catalysts in electrochemical applications because of their large surface area. Nickel oxide (NiO) decoration was achieved by drop-casting a nickel-dissolved solution onto vertically aligned silicon nanowire arrays with a carbon shell (SiNW/C). Based on the hybridization of the NiO and silicon nanowire arrays with a carbon shell this study aimed to achieve a synergic effect for the catalytic activity performance. This study demonstrated that the resulting nanomaterial exhibits excellent electrocatalytic activity and performs well as a counter electrode for dye-sensitized solar cells (DSSCs). The compositions of the materials were examined using X-ray diffraction, X-ray photoelectron spectroscopy, and energy dispersive spectroscopy. Their micro- and nano-structures were investigated using scanning electron microscopy and transmission electron microscopy. The electrochemical activity toward I-/I3- was examined using cyclic voltammetry and electrochemical impedance spectroscopy. The obtained peak power conversion efficiency of the DSSC based on the NiO@SiNW/C counter electrode was 9.49%, which was greater than that of the DSSC based on the Pt counter electrode.To improve the catalytic activity of a material, it is critical to maximize the effective surface area by directly contacting the electrolyte. Nanowires are a promising building block for catalysts in electrochemical applications because of their large surface area. Nickel oxide (NiO) decoration was achieved by drop-casting a nickel-dissolved solution onto vertically aligned silicon nanowire arrays with a carbon shell (SiNW/C). Based on the hybridization of the NiO and silicon nanowire arrays with a carbon shell this study aimed to achieve a synergic effect for the catalytic activity performance. This study demonstrated that the

  10. Interconnection of multichannel polyimide electrodes using anisotropic conductive films (ACFs) for biomedical applications.

    PubMed

    Baek, Dong-Hyun; Park, Ji Soo; Lee, Eun-Joong; Shin, SuJung; Moon, Jin-Hee; Pak, James Jungho; Lee, Sang-Hoon

    2011-05-01

    In this paper, we propose a method for interconnecting soft polyimide (PI) electrodes using anisotropic conductive films (ACFs). Reliable and automated bonding was achieved through development of a desktop thermocompressive bonding device that could simultaneously deliver appropriate temperatures and pressures to the interconnection area. The bonding conditions were optimized by changing the bonding temperature and bonding pressure. The electrical properties were characterized by measuring the contact resistance of the ACF bonding area, yielding a measure that was used to optimize the applied pressure and temperature. The optimal conditions consisted of applying a pressure of 4 kg f/cm(2) and a temperature of 180 °C for 20 s. Although ACF base bonding is widely used in industry (e.g., liquid crystal display manufacturing), this study constitutes the first trial of a biomedical application. We performed a preliminary in vivo biocompatibility investigation of ACF bonded area. Using the optimized temperature and pressure conditions, we interconnected a 40-channel PI multielectrode device for measuring electroencephalography (EEG) signals from the skulls of mice. The electrical properties of electrode were characterized by measuring the impedance. Finally, EEG signals were measured from the mice skulls using the fabricated devices to investigate suitability for application to biomedical devices. PMID:21189231

  11. Advanced composite applications for sub-micron biologically derived microstructures

    NASA Technical Reports Server (NTRS)

    Schnur, J. M.; Price, R. R.; Schoen, P. E.; Bonanventura, Joseph; Kirkpatrick, Douglas

    1991-01-01

    A major thrust of advanced material development is in the area of self-assembled ultra-fine particulate based composites (micro-composites). The application of biologically derived, self-assembled microstructures to form advanced composite materials is discussed. Hollow 0.5 micron diameter cylindrical shaped microcylinders self-assemble from diacetylenic lipids. These microstructures have a multiplicity of potential applications in the material sciences. Exploratory development is proceeding in application areas such as controlled release for drug delivery, wound repair, and biofouling as well as composites for electronic and magnetic applications, and high power microwave cathodes.

  12. Mechanical properties of carbon fiber composites for environmental applications

    SciTech Connect

    Andrews, R.; Grulke, E.

    1996-10-01

    Activated carbon fiber composites show great promise as fixed-bed catalytic reactors for use in environmental applications such as flue gas clean-up and ground water decontamination. A novel manufacturing process produces low density composites from chopped carbon fibers and binders. These composites have high permeability, can be activated to have high surface area, and have many potential environmental applications. This paper reports the mechanical and flow properties of these low density composites. Three point flexural strength tests were used to measure composite yield strength and flexural moduli. Composites containing over 10 pph binder had an adequate yield strength of about 200 psi at activations up to 40% weight loss. The composites were anisotropic, having along-fiber to cross-fiber yield strength ratios between 1.2 and 2.0. The friction factor for flow through the composites can be correlated using the fiber Reynolds number, and is affected by the composite bulk density.

  13. Electrophoretic lithium iron phosphate/reduced graphene oxide composite for lithium ion battery cathode application

    NASA Astrophysics Data System (ADS)

    Huang, Yuan; Liu, Hao; Lu, Yi-Chun; Hou, Yanglong; Li, Quan

    2015-06-01

    A binder/additive free composite electrode of lithium iron phosphate/reduced graphene oxide with ultrahigh lithium iron phosphate mass ratio (91.5 wt% of lithium iron phosphate) is demonstrated using electrophoresis. The quasi-spherical lithium iron phosphate particles are uniformly connected to and/or wrapped by three-dimensional networks of reduced graphene oxide nanosheets, with intimate contact formed between the two. Enhanced capacity is achieved in the electrophoretic composite cathode, when compared to either the conventional one or composite cathode formed by mechanically mixing lithium iron phosphate and reduced graphene oxide. The present methodology is simple and does not disturb the active material growth process. It can be generally applied to a variety of active material systems for both cathode and anode applications in lithium ion batteries.

  14. Electrical, Mechanical, and Capacity Percolation Leads to High-Performance MoS2/Nanotube Composite Lithium Ion Battery Electrodes.

    PubMed

    Liu, Yuping; He, Xiaoyun; Hanlon, Damien; Harvey, Andrew; Khan, Umar; Li, Yanguang; Coleman, Jonathan N

    2016-06-28

    Advances in lithium ion batteries would facilitate technological developments in areas from electrical vehicles to mobile communications. While two-dimensional systems like MoS2 are promising electrode materials due to their potentially high capacity, their poor rate capability and low cycle stability are severe handicaps. Here, we study the electrical, mechanical, and lithium storage properties of solution-processed MoS2/carbon nanotube anodes. Nanotube addition gives up to 10(10)-fold and 40-fold increases in electrical conductivity and mechanical toughness, respectively. The increased conductivity results in up to a 100× capacity enhancement to ∼1200 mAh/g (∼3000 mAh/cm(3)) at 0.1 A/g, while the improved toughness significantly boosts cycle stability. Composites with 20 wt % nanotubes combine high reversible capacity with excellent cycling stability (e.g., ∼950 mAh/g after 500 cycles at 2 A/g) and high rate capability (∼600 mAh/g at 20 A/g). The conductivity, toughness, and capacity scale with nanotube content according to percolation theory, while the stability increases sharply at the mechanical percolation threshold. We believe that the improvements in conductivity and toughness obtained after addition of nanotubes can be transferred to other electrode materials, such as silicon nanoparticles. PMID:27203558

  15. Silver nanoflower-reduced graphene oxide composite based micro-disk electrode for insulin detection in serum.

    PubMed

    Yagati, Ajay Kumar; Choi, Yonghyun; Park, Jinsoo; Choi, Jeong-Woo; Jun, Hee-Sook; Cho, Sungbo

    2016-06-15

    Sensitive and selective determination of protein biomarkers remains a significant challenge due to the existence of various biomarkers in human body at a low concentration level. Therefore, new technologies were incessantly steered to detect tiny biomarkers at a low concentration level, yet, it is difficult to develop reliable, stable and sensitive detection methods for disease diagnostics. Therefore, the present study demonstrates a methodology to detect insulin in serum at low levels based on Ag nanoflower (AgNF) decorated reduced graphene oxide (rGO) modified micro-disk electrode arrays (MDEAs). The morphology of AgNF-rGO composite was characterized by scanning electron microscopy, the structure was analyzed using X-ray diffraction patterns and Raman spectra. The hybrid interface exhibited enhanced electrical conductivity when compared with its individual elements and had improved capturing ability for antibody-antigen binding towards insulin detection. In order to measure quantitatively the insulin concentration in PBS and human serum, the change in impedance (ΔZ) from electrochemical impedance spectroscopy was analyzed for various concentrations of insulin in [Fe(CN)6](3-/4-) redox couple. The electrode with adsorbed antibodies showed an increase in ΔZ for the addition of antigen concentrations over a working range of 1-1000 ng mL(-1). The detection limits were 50 and 70 pg mL(-1) in PBS and human serum, respectively. PMID:26852199

  16. Impedancemetric NOx Sensing Using Yttria-Stabilized Zirconia (YSZ) Electrolyte and YSZ/Cr2O3 Composite Electrodes

    SciTech Connect

    Martin, L P; Woo, L Y; Glass, R S

    2006-11-01

    An impedancemetric method for NO{sub x} sensing using an yttria-stabilized zirconia (YSZ) based electrochemical cell is described. The sensor cell consists of a planar YSZ electrolyte and two identical YSZ/Cr{sub 2}O{sub 3} composite electrodes exposed to the test gas. The sensor response to a sinusoidal ac signal applied between the two electrodes is measured via two parameters calculated from the complex impedance, the modulus |Z| and phase angle {Theta}. While either of these parameters can be correlated to the NO{sub x} concentration in the test gas, {Theta} was found to provide a more robust metric than |Z|. At frequencies below approximately 100 Hz, {Theta} is sensitive to both the NO{sub x} and O{sub 2} concentrations. At higher frequencies, {Theta} is predominantly affected by the O{sub 2} concentration. A dual frequency measurement is demonstrated to compensate for changes in the O{sub 2} background between 2 and 18.9%. Excellent sensor performance is obtained for NO{sub x} concentrations in the range of 8-50 ppm in background. An equivalent circuit model was used to extract fitting parameters from the impedance spectra for a preliminary analysis of NO{sub x} sensing mechanisms.

  17. Optimal Sulfur Content Study on Electrochemical Properties of Graphene Nanosheets/Single-Walled Carbon Nanotube Composite Electrodes.

    PubMed

    Son, Ki-Soo; Jung, Yongju; Kim, Seok

    2015-11-01

    Graphene nanosheets (GNS)/sulfur were synthesized by heating a mixture of GNS and elemental sulfur. Single-walled carbon nanotubes (SWCNTs) were added into the composites as a modifier on GNS layers. The embedment of SWCNTs into composites can inhibit agglomeration of GNS and increase an effective surface area of the structural electroactive sites. The electrochemical property of the composites was investigated using cyclic voltammetry (CV), charge-discharge curves and cycle performance. The micro-structure and morphology of the composites were examined by scanning electron microscopy (SEM), transition electron microscopy (TEM). The GNS/SWCNT/sulfur composites exhibited the improved current density of redox reaction and the cycle stability for an application of rechargeable lithium-sulfur cells. PMID:26726649

  18. Synthesis and Applications of Large Area Graphene-Based Electrode Systems

    NASA Astrophysics Data System (ADS)

    Paul, Rajat Kanti

    Graphene is a single sheet of carbon atoms with outstanding electrical and physical properties and being exploited for applications in electronics, sensors, fuel cells, photovoltaics and energy storage. However, practical designs of graphene-based electrode systems and related experimental implementations are required to realize their widespread applications in nano- to bioelectronics. In this dissertation, different graphene-based electrode systems having metallic and semiconducting properties are synthesized optimizing process conditions. Also realized is the potential of the fabricated electrode systems by applying them in practical applications such as sensor devices and fuel cells. The zero bandgap of semimetal graphene still limits its application as an effective field-effect transistor device or a chemiresistor sensor operating at room temperature. It has been shown theoretically and experimentally that graphene nanoribbons (GNRs) or nanomeshes (GNMs) can attain a bandgap that is large enough for a transistor device, and hence would show high sensitivity to various gaseous species or biomolecules. Large-area mono- and bilayer graphene films are synthesized by a simple chemical vapor deposition (CVD) technique depending on the carbon precursors such as methane, acetylene and ethanol, and the results are compared using optical microscopy (OM), Raman spectroscopy, high-resolution transmission electron microscopy (HRTEM) and x-ray photoelectron spectroscopy (XPS). A simple reactive ion etching (RIE) combined with well-established nanosphere lithography is performed on the synthesized CVD-grown monolayer graphene platform to fabricate large area GNMs with specific dimension and periodicity. The fabricated GNMs chemiresistor sensor devices show excellent sensitivity towards NO2 and NH 3, significantly higher than their film counterparts. The GNM sensor devices exhibit sensitivities of about 4.32%/ppm (parts-per-million) in NO 2 and 0.71%/ppm in NH3 with estimated

  19. Bioelectrochemical degradation of urea at platinized boron doped diamond electrodes for bioregenerative applications

    NASA Astrophysics Data System (ADS)

    Nicolau, Eduardo; Gonzalez, Ileana; Nicolau, Eduardo; Cabrera, Carlos R.

    The recovery of potable water from space mission wastewater is critical for the life support and environmental health of crew members in long-term missions. NASA estimates reveal that at manned space missions 0.06 kg/person·day of urine is produced, with urea and various salts as its main components. Current spacecraft water reclamation strategies include the utilization of not only multifiltration systems (MF) and reverse osmosis (RO), but also biological components to deal with crew urine streams. In this research we explore the utilization of urease (EC 3.5.1.5) to convert urea directly to nitrogen by the in-situ utilization of the reaction products, to increase the amount of clean water in future space expeditions. First of all, platinum was electrodeposited on boron doped diamond electrodes by cycling the potential between -0.2 V and 1.0 V in metal/0.5 M H2SO4 solution. SEM images of the electrodes showed a distribution of platinum nanoparticles ranging between 50 nm and 300 nm. The biochemical reaction of urease in nature produces ammonia and carbon dioxide from urea. Based on this, Cyclic Voltammetry experiments of an ammonium acetate solution at pH 10 were performed showing an anodic peak at -0.3 V vs. Ag/AgCl due to the ammonia oxidation. Then, a urease solution (Jack Bean) was poured into the electrochemical cell and subsequent additions of urea were performed with the potential held at -0.3 V in order to promote ammonia oxidation. Chronoamperometry data shows that with more than five urea additions the enzyme still responding by producing ammonia, which is being subsequently oxidized at the electrode surface and producing molecular nitrogen. This research has tremendous applications for future long-term space missions since the reaction byproducts could be used for a biomass subsystem (in-situ resource recovery), while generating electricity from the same process.

  20. Enhancement of the efficiency of dye-sensitized solar cell with multi-wall carbon nanotubes/polypyrrole composite counter electrodes prepared by electrophoresis/electrochemical polymerization

    SciTech Connect

    Luo, Jun; Niu, Hai-jun; Wen, Hai-lin; Wu, Wen-jun; Zhao, Ping; Wang, Cheng; Bai, Xu-duo; Wang, Wen

    2013-03-15

    Graphical abstract: The overall energy conversion efficiency of the DSSC employing the MWCNT/PPy CE reached 3.78%. Compared with a reference DSSC using single MWCNT film CE with efficiency of 2.68%, the energy conversion efficiency was increased by 41.04%. Highlights: ► MWCNT/PPy composite film prepared by electrodeposition layer by layer was used as counter electrode in DSSC. ► The overall energy conversion efficiency of the DSSC was 3.78% by employing the composite film. ► The energy conversion efficiency increased by 41.04% compared with efficiency of 2.68% by using the single MWCNT film. ► We analyzed the mechanism and influence factor of electron transfer in the composite electrode by EIS. - Abstract: For the purpose of replacing the precious Pt counter electrode in dye-sensitized solar cells (DSSCs) with higher energy conversion efficiency, multi-wall carbon nanotube (MWCNT)/polypyrrole (PPy) double layers film counter electrode (CE) was fabricated by electrophoresis and cyclic voltammetry (CV) layer by layer. Atom force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscope (TEM) demonstrated the morphologies of the composite electrode and Raman spectroscopy verified the PPy had come into being. The overall energy conversion efficiency of the DSSC employing the MWCNT/PPy CE reached 3.78%. Compared with a reference DSSC using single MWCNT film CE with efficiency of 2.68%, the energy conversion efficiency was increased by 41.04%. The result of impedance showed that the charge transfer resistance R{sub ct} of the MWCNT/PPy CE had the lowest value compared to that of MWCNT or PPy electrode. These results indicate that the composite film with high conductivity, high active surface area, and good catalytic properties for I{sub 3}{sup −} reduction can potentially be used as the CE in a high-performance DSSC.

  1. Applicability of thermoplastic composites for space structures

    NASA Technical Reports Server (NTRS)

    Hoggatt, J. T.; Kushner, M.

    1978-01-01

    The discussion defines a thermoplastic resin and compares the structural and environmental properties and the fabrication and repairability of the thermoplastic composite with a typical epoxy composite. Low labor costs exhibited by the thermoplastic composites make them a priority consideration for use in space structure.

  2. Graphene/Nafion composite film modified glassy carbon electrode for simultaneous determination of paracetamol, aspirin and caffeine in pharmaceutical formulations.

    PubMed

    Yiğit, Aydın; Yardım, Yavuz; Çelebi, Metin; Levent, Abdulkadir; Şentürk, Zühre

    2016-09-01

    A graphene-Nafion composite film was fabricated on the glassy carbon electrode (GR-NF/GCE), and used for simultaneous determination of paracetamol (PAR), aspirin (ASA) and caffeine (CAF). The electrochemical behaviors of PAR, ASA and CAF were investigated by cyclic voltammetry and square-wave adsorptive anodic stripping voltammetry. By using stripping one for simultaneous determination of PAR, ASA and CAF, their electrochemical oxidation peaks appeared at +0.64, 1.04 and 1.44V, and good linear current responses were obtained with the detection limits of 18ngmL(-1) (1.2×10(-9)M), 11.7ngmL(-1) (6.5×10(-8)M) and 7.3ngmL(-1) (3.8×10(-8)M), respectively. Finally, the proposed electrochemical sensor was successfully applied for quantifying PAR, ASA and CAF in commercial tablet formulations. PMID:27343573

  3. Polymer coated Capacitive Deionization Electrode for Desalination: A mini review

    NASA Astrophysics Data System (ADS)

    Gaikwad, Mahendra S.; Balomajumder, Chandrajit

    2016-02-01

    This mini review deals with a recently developing water purification technology, i.e. capacitive deionization. It presents the current progress achieved with polymer coated electrodes in capacitive deionization for desalination. The introduction covers capacitive deionization, application of polymer or polymer composite in capacitive deionization electrode, comparative study and discussion on fabrication of electrode. This paper aims at indicating novel research prospects in capacitive deionization technology for desalination.

  4. Magneto-electric interactions at bending resonance in an asymmetric multiferroic composite: Theory and experiment on the influence of electrode position

    NASA Astrophysics Data System (ADS)

    Sreenivasulu, G.; Qu, P.; Petrov, V. M.; Qu, Hongwei; Srinivasan, G.

    2015-05-01

    In magnetostrictive-piezoelectric bilayers the strength of mechanical strain mediated magneto-electric (ME) interactions shows a resonance enhancement at bending modes. Such composites when operating under frequency modulation at bending resonance have very high ME sensitivity and are of importance for ultrasensitive magnetometers. This report provides an avenue for further enhancement in the ME sensitivity by strategic positioning of the electrodes in the bilayer. We discuss the theory and measurements on the dependence of ME coupling on the position of electrodes in a lead zirconate titanate-permendur bilayer. Samples of effective length L with full electrodes and partial electrodes of length l = L/3 are studied. A five-fold increase in ME voltage coefficient (MEVC) at bending resonance and a 75% increase in low-frequency MEVC are measured as the partial electrode position is moved from the free-end to clamped-end of the bilayer. When the partial electrode is close to the clamped end, the low-frequency and resonance MEVC are 22% and 45% higher, respectively, than for fully electroded bilayer. According to the model discussed here these observations could be attributed to non-uniform stress along the sample length under flexural deformation. Such deformations are stronger at the free-end than at the clamped-end, thereby reducing the stress produced by applied magnetic fields and a reduction in MEVC. Estimates of MEVC are in good agreement with the data.

  5. Graphene nanocomposites for electrochemical cell electrodes

    DOEpatents

    Zhamu, Aruna; Jang, Bor Z.; Shi, Jinjun

    2015-11-19

    A composite composition for electrochemical cell electrode applications, the composition comprising multiple solid particles, wherein (a) a solid particle is composed of graphene platelets dispersed in or bonded by a first matrix or binder material, wherein the graphene platelets are not obtained from graphitization of the first binder or matrix material; (b) the graphene platelets have a length or width in the range of 10 nm to 10 .mu.m; (c) the multiple solid particles are bonded by a second binder material; and (d) the first or second binder material is selected from a polymer, polymeric carbon, amorphous carbon, metal, glass, ceramic, oxide, organic material, or a combination thereof. For a lithium ion battery anode application, the first binder or matrix material is preferably amorphous carbon or polymeric carbon. Such a composite composition provides a high anode capacity and good cycling response. For a supercapacitor electrode application, the solid particles preferably have meso-scale pores therein to accommodate electrolyte.

  6. Comparison of electrode structures and photovoltaic properties of porphyrin-sensitized solar cells with TiO2 and Nb, Ge, Zr-added TiO2 composite electrodes.

    PubMed

    Imahori, Hiroshi; Hayashi, Shinya; Umeyama, Tomokazu; Eu, Seunghun; Oguro, Akane; Kang, Soonchul; Matano, Yoshihiro; Shishido, Tetsuya; Ngamsinlapasathian, Supachai; Yoshikawa, Susumu

    2006-12-19

    Electrode structures and photovoltaic properties of porphyrin-sensitized solar cells with TiO2 and Nb-, Ge-, and Zr-added TiO2 composite electrodes were examined to disclose the effects of partial substitution of Ti atom by the other metals in the composite electrodes. The TiO2 and Nb-, Ge-, and Zr-added TiO2 composite electrodes were prepared by sol-gel process using laurylamine hydrochloride as a template for the formation of micellar precursors yielding well-defined mesoporous nanocrystalline structures, as in the cases of the formation of silica and titania tubules and nanoparticles by the templating mechanism. The TiO2 and Nb-, Ge-, and Zr-added TiO2 composite electrodes were characterized by transmission electron microscopy, BET surface area analysis, X-ray diffraction analysis, Raman spectroscopy, and impedance measurements. The TiO2 anatase nanocrystalline structure is retained after doping a small amount (5 mol %) of Nb, Ge, or Zr into the TiO2 structure, suggesting the homogeneous distribution of the doped metals with replacing Ti atom by the doped metal. The power conversion efficiency of the porphyrin-sensitized solar cells increases in the order Zr-added TiO2 (0.8%) < Nb-added TiO2 (1.2%) < TiO2 (2.0%) < Ge-added TiO2 cells (2.4%) under the same conditions. The improvement of cell performance of the Ge-added TiO2 cell results from the negative shift of the conduction band of the Ge-added TiO2 electrode. The Ge-added TiO2 cell exhibited a maximum power conversion efficiency of 3.5% when the porphyrin was adsorbed onto the surface of the Ge-added TiO2 electrode with a thickness of 4 microm in MeOH for 1 h. PMID:17154633

  7. Mechanical properties of carbon fiber composites for environmental applications

    SciTech Connect

    Andrews, R.; Grulke, E.; Kimber, G.

    1996-12-31

    Activated carbon fiber composites show great promise as fixed-bed catalytic reactors for use in environmental applications such as flue gas clean-up and ground water decontamination. A novel manufacturing process produces low density composites from chopped carbon fibers and binders. These composites have high permeability, can be activated to have high surface area, and have many potential environmental applications. This paper reports the mechanical and flow properties of these low density composites. Three point flexural strength tests were used to measure composite yield strength and flexural moduli. Composites containing over 10 pph binder had an adequate yield strength of about 200 psi at activations up to 40% weight loss. The composites were anisotropic, having along-fiber to cross-fiber yield strength ratios between 1.2 and 2.0. The pressure drop of air through the composites correlated with the gas velocity, and showed a dependence on sample density.

  8. High specific surface gold electrode on polystyrene substrate: Characterization and application as DNA biosensor.

    PubMed

    Yang, Zhiliu; Liu, Yichen; Lu, Wei; Yuan, Qingpan; Wang, Wei; Pu, Qiaosheng; Yao, Bo

    2016-05-15

    In the past decades, many efforts have been made to improve the sensitivity and specificity of electrochemical DNA biosensors. However, it is still strongly required to develop disposable and reliable DNA biosensors for wide and practical application. In this article, we reported superior electrochemical properties of an integrated plastic-gold electrode (PGE) fabricated in-house by chemical plating on polystyrene substrate. PGEs were found having extremely high capacity of DNA immobilization compared with gold electrodes fabricated by standard sputtering based photolithography. Unique nano-structured surface was observed on PGEs through morphology techniques, which would to some extend give an explanation to higher capacity of DNA immobilization on PGEs. A probable mechanism of carboxylic acid produced on polystyrene substrate after exposure to UV irradiation was proposed and discussed for the first time. This biosensor was applied to detection and manipulate of DNA hybridization. Detection limit of 7.2×10(-11)M and 1-500nM of linearity range was obtained. PMID:26992524

  9. The application of exfoliated graphite electrode in the electrochemical degradation of p-nitrophenol in water.

    PubMed

    Ntsendwana, Bulelwa; Peleyeju, Moses G; Arotiba, Omotayo A

    2016-06-01

    We report the application of exfoliated graphite (EG) as an electrode material in the electrochemical degradation of p-nitrophenol in water. Bulk electrolysis (degradation) of p-nitrophenol was carried out at a potential of 2.0 V (vs. Ag/AgCl) in the presence of 0.1 M Na2SO4 supporting electrolyte, while UV-Vis spectrophotometry was used to monitor the degradation efficiency. An initial p-nitrophenol load concentration of 0.2 mM for 3 h electrolysis time was studied under the optimized conditions of pH 7, and 10 mAcm(-2) current density. The electro-degradation reaction displayed a pseudo-first-order kinetic behavior with a rate constant (kr) of 11×10(-3) min(-1). The removal efficiency was found to be 91.5%. Chromatography coupled with time of flight mass spectrometry revealed p-benzoquinone as a major intermediate product. These results demonstrate the potential and viability of electrochemical technology as an alternative approach to water treatment using a low cost graphite electrode. PMID:26979139

  10. Synthesis and characterization of DSSC by using Pt nano-counter electrode: photosensor applications

    NASA Astrophysics Data System (ADS)

    Yahia, I. S.; AlFaify, S.; Al-ghamdi, Attieh A.; Hafez, Hoda S.; EL-Bashir, S.; Al-Bassam, A.; El-Naggar, A. M.; Yakuphanoglu, F.

    2016-06-01

    Pt electrode prepared by chemical method has been employed as counter electrode in dye-sensitized solar cell. TiO2 nanomaterial was deposited on fluorine-doped tin oxide substrate to be used as photoanode. Structure of the TiO2 and Pt films was investigated by atomic force microscope. The effect of illumination intensity on the photovoltaic parameters such as open circuit voltage, short circuit current density, output power, fill factor and efficiency of these cells was investigated in the range 2.5-130 mW/cm-2. The cell efficiency is stable above 70 mW/cm2. The fill factor is almost constant all over the studied range of illumination intensity. Impedance spectroscopy of the studied device as the summary measurements of the capacitance-voltage, conductance-voltage and series resistance-voltage characteristics were investigated in a wide range of frequencies (5 kHz-1 MHz). At low frequencies, the capacitance has positive values with peak around the origin due to the interfaces. At 200 and 300 kHz, the capacitance is inverted to negative with further increasing of the positive biasing voltage. Above 400 kHz, C-V profile shows complete negative behavior. Also, the impedance-voltage and phase-voltage characteristics were investigated. This cell shows a new promising device for photosensor applications due to high sensitivity in low and high illuminations.

  11. The application of carbon aerogel electrodes to desalination {ampersand} waste treatment

    SciTech Connect

    Farmer, J.C., Tran, T.D., Richardson, J.H., Fix, D.V., May, S.C., Thomson, S.L.

    1997-08-01

    An electrically-regenerated electrosorption process known as carbon aerogel capacitive deionization (CDI) has been developed by Lawrence Livermore National Laboratory (LLNL) for continuously removing ionic impurities from aqueous streams. A salt solution flows through an unobstructed channel formed by numerous pairs of parallel carbon aerogel electrodes. Each electrode has a very high Brunauer-Emmet-Teller (BET) surface area (2.0-5.4 x 1O{sup 6} ft{sup 2} lb{sup -1} or 400-1100) and very low electrical resistivity (< 40 m{omega} cm). Surface areas of 1.3 x 10{sup 7} ft{sup 2} lb{sup -1} (2600 m{sup 2} g{sup -1}) have been achieved activation. After polarization, anions and cations are removed from the electrolyte by the imposed electric field and electrosorbed onto the carbon aerogel. The solution is thus separated into two streams, concentrate and purified water. Based upon this analysis, it is concluded that carbon aerogel CDI may be an energy-efficient alternative to electrodialysis and reverse osmosis for the desalination of brackish water (< 5000 ppm), provided that cell geometries and aerogel properties are carefully tailored for such applications.

  12. Preparation and electrochemical characterization of polyaniline/activated carbon composites as an electrode material for supercapacitors.

    PubMed

    Oh, Misoon; Kim, Seok

    2012-01-01

    Polyaniline (PANI)/activated carbon (AC) composites were prepared by a chemical oxidation polymerization. To find an optimum ratio between PANI and AC which shows superior electrochemical properties, the preparation was carried out in changing the amount of added aniline monomers. The morphology of prepared composites was investigated by scanning electron microscopy (SEM) and transmission electron microscope (TEM). The structural and thermal properties were investigated by Fourier transform infrared spectra (FT-IR) and thermal gravimetric analysis (TGA), respectively. The electrochemical properties were characterized by cyclic voltammetry (CV). Composites showed a summation of capacitances that consisted of two origins. One is double-layer capacitance by ACs and the other is faradic capacitance by redox reaction of PANI. Fiber-like PANIs are coated on the surface of ACs and they contribute to the large surface for redox reaction. The vacancy among fibers provided the better diffusion and accessibility of ion. High capacitances of composites were originated from the network structure having vacancy made by PANI fibers. It was found that the composite prepared with 5 ml of aniline monomer and 0.25 g of AC showed the highest capacitance. Capacitance of 771 F/g was obtained at a scan rate of 5 mV/s. PMID:22524013

  13. Optical properties and electrochemical dealloying of Gold-Silver alloy nanoparticles immobilized on composite thin-film electrodes

    NASA Astrophysics Data System (ADS)

    Starr, Christopher A.

    Gold-silver alloy nanoparticles (NPs) capped with adenosine 5'-triphosphate were synthesized by borohydride reduction of dilute aqueous metal precursors. High-resolution transmission electron microscopy showed the as-synthesized particles to be spherical with average diameters ~4 nm. Optical properties were measured by UV-Visible spectroscopy (UV-Vis), and the formation of alloy NPs was verified across all gold:silver ratios by a linear shift in the plasmon band maxima against alloy composition. The molar absorptivities of the NPs decreased non-linearly with increasing gold content from 2.0 x 108 M-1 cm-1 (lambdamax = 404 nm) for pure silver to 4.1 x 107 M-1 cm -1 (lambdamax = 511 nm) for pure gold. The NPs were immobilized onto transparent indium-tin oxide composite electrodes using layer-by-layer (LbL) deposition with poly(diallyldimethylammonium) acting as a cationic binder. The UV-Vis absorbance of the LbL film was used to calculate the surface coverage of alloy NPs on the electrode. Typical preparations had average NP surface coverages of 2.8 x 10-13 mol NPs/cm2 (~5% of cubic closest packing) with saturated films reaching ~20% of ccp for single-layer preparations (1.0 ~ 10-12 mol NPs/cm2). X-ray photoelectron spectroscopy confirmed the presence of alloy NPs in the LbL film and showed silver enrichment of the NP surfaces by ~9%. Irreversible oxidative dissolution (dealloying) of the less noble silver atoms from the NPs on LbL electrodes was performed by cyclic voltammetry (CV) in sulfuric acid. Alloy NPs with higher gold content required larger overpotentials for silver dealloying. Dealloying of the more-noble gold atoms from the alloy NPs was also achieved by CV in sodium chloride. The silver was oxidized first to cohesive silver chloride, and then gold dealloyed to soluble HAuCl 4- at higher potentials. Silver oxidation was inhibited during the first oxidative scan, but subsequent cycles showed typical, reversible silver-to-silver chloride voltammetry. The

  14. Synthesis and electronic applications of oxide-metal eutectic composites

    SciTech Connect

    Holder, J.D.; Cochran, J.K.; Hill, D.N.; Chapman, A.T.; Clark, G.W.

    1980-01-01

    A review is given of important developments in the synthesis of oxide-metal eutectic composites and the composite application in the continuing development of field emitters. Known metal oxide-metal binary and ternary eutectic systems are listed. The synthesis, electrical conductivity, thermodynamics, and applications are discussed. (FS)

  15. Graphite fiber reinforced glass matrix composites for aerospace applications

    NASA Technical Reports Server (NTRS)

    Prewo, K. M.; Bacon, J. F.; Dicus, D. L.

    1979-01-01

    The graphite fiber reinforced glass matrix composite system is described. Although this composite is not yet a mature material, it possesses low density, attractive mechanical properties at elevated temperatures, and good environmental stability. Properties are reported for a borosilicate glass matrix unidirectionally reinforced with 60 volume percent HMS graphite fiber. The flexural strength and fatigue characteristics at room and elevated temperature, resistance to thermal cycling and continuous high temperature oxidation, and thermal expansion characteristics of the composite are reported. The properties of this new composite are compared to those of advanced resin and metal matrix composites showing that graphite fiber reinforced glass matrix composites are attractive for aerospace applications.

  16. Nanostructured Si/Sn-Ni/C composite as negative electrode for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Edfouf, Z.; Cuevas, F.; Latroche, M.; Georges, C.; Jordy, C.; Hézèque, T.; Caillon, G.; Jumas, J. C.; Sougrati, M. T.

    2011-05-01

    A nanostructured composite with overall atomic composition Ni0.14Sn0.17Si0.32Al0.037C0.346 has been prepared combining powder metallurgy and mechanical milling techniques for being used as anode material in Li-ion battery. Chemical and structural properties of the nanocomposite have been determined by X-ray diffraction (XRD), 119Sn Transmission Mössbauer Spectroscopy (TMS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The composite consists of Si particles with typical size ∼150 nm embedded in a poorly crystallized and complex multielemental matrix. The matrix is composed mostly by Ni3.4Sn4, and disordered carbon. Electrochemical evaluation shows a high reversible capacity of 920 mAh g-1, with reasonable reversible capacity retention (∼0.1% loss/cycle) over 280 cycles.

  17. Performance and cycle life of carbon- and conductive-based air electrodes for rechargeable Zn-air battery applications

    NASA Astrophysics Data System (ADS)

    Chellapandi Velraj, Samgopiraj

    , the LaNi0.8Co0.2O 3-based electrode was unstable during OER after a short time period, while the LaNi0.8Co0.2O3 and NiCo2O 4-based electrodes were stable. The LaNi0.8Co 0.2O3-based electrodes had reasonable ORR activity but stability during oxygen reduction reaction (ORR) was limited due to the flooding of the electrode caused by the extremely hydrophilic nature of the perovskite electrode. On the contrary, the NiCo2O4-based electrode showed reasonable stability for both ORR and OER even during aggressive cyclic lifetime testing at a higher current density of 50 mA.cm-2 and could be a potential support material to replace carbon in bifunctional air electrodes for rechargeable Zn-air battery applications.

  18. Integration of a Graphite/PMMA CompositeElectrode into a Poly(methyl methacrylate) (PMMA) Substrate for Electrochemical Detection in Microchips

    PubMed Central

    Regel, Anne; Lunte, Susan

    2013-01-01

    Traditional fabrication methods for polymer microchips, the bonding of two substrates together to form the microchip, can make the integration of carbon electrodes difficult. We have developed a simple and inexpensive method to integrate graphite/PMMA composite electrodes (GPCEs) into a PMMA substrate. These substrates can be bonded to other PMMA layers using a solvent-assisted thermal bonding method. The optimal composition of the GPCEs for electrochemical detection was determined using cyclic voltammetry with dopamine as a test analyte. Using the optimized GPCEs in an all-PMMA flow cell with flow injection analysis, it was possible to detect 50 nM dopamine under the best conditions. These electrodes were also evaluated for the detection of dopamine and catechol following separation by microchip electrophoresis (ME). PMID:23670816

  19. Application of copper-carbon fiber composites to power semiconductor devices

    NASA Technical Reports Server (NTRS)

    Kuniya, Keiichi; Arakawa, Hideo; Sakaue, Tadashi; Minorikawa, Hitoshi; Akeyama, Kenji; Sakamoto, Tatsuji

    1988-01-01

    Copper-carbon composite electrodes are used in a series of power semiconductor devices, i.e., resin molded diodes, button-type diodes, stud-type diodes, power modules, and integrated circuit igniter modules. The properties of these power semiconductor devices compare favorably with those conventional devices using Mo or W electrodes. In thermal fatigue tests, no degradation in the electrical and mechanical characteristics of these devices are observed. The new composite electrode with carbon fibers satisfies all of the major requirements for the electrodes in power semiconductor devices.

  20. Tetrabutylammonium-modified clay film electrodes: characterization and application to the detection of metal ions.

    PubMed

    Maghear, Adela; Tertiş, Mihaela; Fritea, Luminţa; Marian, Iuliu O; Indrea, Emil; Walcarius, Alain; Săndulescu, Robert

    2014-07-01

    This work describes the preparation and characterization of smectite clay partially exchanged with tetrabutylammonium ions (TBA(+)) and its subsequent deposition onto glassy carbon electrode (GCE) for application to the preconcentration electroanalysis of metal ions (Cd, Pb, and Cu). Such partial exchange of TBA(+) induces the expansion of the interlayer region between the clay sheets (as ascertained by XRD) while maintaining its ion exchange capacity, which resulted in enhanced mass transport rates (as pointed out by electrochemical monitoring of permeability properties of these thin (organo)clay films on GCE). This principle was applied here to the anodic stripping square wave voltammetric analysis of metal ions after accumulation at open circuit. Among others, detection limits as low as 3.6×10(-8)M for copper and 7.2×10(-8)M for cadmium have been achieved. PMID:24840412

  1. Electrocatalytic activity of NiO on silicon nanowires with a carbon shell and its application in dye-sensitized solar cell counter electrodes.

    PubMed

    Kim, Junhee; Jung, Cho-long; Kim, Minsoo; Kim, Soomin; Kang, Yoonmook; Lee, Hae-seok; Park, Jeounghee; Jun, Yongseok; Kim, Donghwan

    2016-04-14

    To improve the catalytic activity of a material, it is critical to maximize the effective surface area by directly contacting the electrolyte. Nanowires are a promising building block for catalysts in electrochemical applications because of their large surface area. Nickel oxide (NiO) decoration was achieved by drop-casting a nickel-dissolved solution onto vertically aligned silicon nanowire arrays with a carbon shell (SiNW/C). Based on the hybridization of the NiO and silicon nanowire arrays with a carbon shell this study aimed to achieve a synergic effect for the catalytic activity performance. This study demonstrated that the resulting nanomaterial exhibits excellent electrocatalytic activity and performs well as a counter electrode for dye-sensitized solar cells (DSSCs). The compositions of the materials were examined using X-ray diffraction, X-ray photoelectron spectroscopy, and energy dispersive spectroscopy. Their micro- and nano-structures were investigated using scanning electron microscopy and transmission electron microscopy. The electrochemical activity toward I(-)/I3(-) was examined using cyclic voltammetry and electrochemical impedance spectroscopy. The obtained peak power conversion efficiency of the DSSC based on the NiO@SiNW/C counter electrode was 9.49%, which was greater than that of the DSSC based on the Pt counter electrode. PMID:27001286

  2. Direct electrochemical reduction of graphene oxide on ionic liquid doped screen-printed electrode and its electrochemical biosensing application.

    PubMed

    Ping, Jianfeng; Wang, Yixian; Fan, Kai; Wu, Jian; Ying, Yibin

    2011-10-15

    A novel electrochemical biosensing platform using electrochemically reduced graphene oxide (ER-GNO) modified electrode was proposed. This modified electrode was prepared by one-step electrodeposition of the exfoliated GNO sheets onto the ionic liquid doped screen-printed electrode (IL-SPE). The resulting ER-GNO/IL-SPE brought new capabilities for electrochemical devices by combining the advantages of ER-GNO and disposable electrode. Two important biomolecules, nicotinamide adenine dinucleotide (NADH) and hydrogen peroxide (H(2)O(2)), were employed to study the electrochemical performance of the ER-GNO/IL-SPE, which exhibited more favorable electron transfer kinetics than the bare IL-SPE. On the basis of the greatly enhanced electrochemical reactivity of H(2)O(2) at the developed electrode, ER-GNO and glucose oxidase constructed disposable biosensor showed better analytical performance for the glucose detection compared with the IL-SPE based biosensor. The linear range for the detection of glucose was from 5.0 μM to 12.0 mM with a detection limit of 1.0 μM. This work provides a useful avenue for implementing ER-GNO as a new generation of electrochemical transducer in disposable electrode, which could expand the scope of graphene constructed electrochemical biosensing devices and hold great promise for routine sensing applications. PMID:21807494

  3. Reliability Evaluation of Base-Metal-Electrode Multilayer Ceramic Capacitors for Potential Space Applications

    NASA Technical Reports Server (NTRS)

    Liu, David (Donhang); Sampson, Michael J.

    2011-01-01

    Base-metal-electrode (BME) ceramic capacitors are being investigated for possible use in high-reliability spacelevel applications. This paper focuses on how BME capacitors construction and microstructure affects their lifetime and reliability. Examination of the construction and microstructure of commercial off-the-shelf (COTS) BME capacitors reveals great variance in dielectric layer thickness, even among BME capacitors with the same rated voltage. Compared to PME (precious-metal-electrode) capacitors, BME capacitors exhibit a denser and more uniform microstructure, with an average grain size between 0.3 and 0.5 m, which is much less than that of most PME capacitors. BME capacitors can be fabricated with more internal electrode layers and thinner dielectric layers than PME capacitors because they have a fine-grained microstructure and do not shrink much during ceramic sintering. This makes it possible for BME capacitors to achieve a very high capacitance volumetric efficiency. The reliability of BME and PME capacitors was investigated using highly accelerated life testing (HALT). Most BME capacitors were found to fail with an early avalanche breakdown, followed by a regular dielectric wearout failure during the HALT test. When most of the early failures, characterized with avalanche breakdown, were removed, BME capacitors exhibited a minimum mean time-to-failure (MTTF) of more than 105 years at room temperature and rated voltage. Dielectric thickness was found to be a critical parameter for the reliability of BME capacitors. The number of stacked grains in a dielectric layer appears to play a significant role in determining BME capacitor reliability. Although dielectric layer thickness varies for a given rated voltage in BME capacitors, the number of stacked grains is relatively consistent, typically around 12 for a number of BME capacitors with a rated voltage of 25V. This may suggest that the number of grains per dielectric layer is more critical than the

  4. Composition and crystal structure of perovskite films attained from electrodes of used car battery

    NASA Astrophysics Data System (ADS)

    Dhiaputra, Ilham; Permana, Bayu; Maulana, Yusep; Inayatie, Yuniar Dwi; Purba, Yonatan R.; Bahtiar, Ayi

    2016-02-01

    Perovskite solar cells have been intensively investigated for high performance and low-cost solid-state solar cells. Perovskite based-lead materials are commonly used as active material for high power conversion efficiency solar cells. Herein, we report our study on the development of used electrodes car battery as a cheap raw lead material to be converted into lead (II) iodide PbI2 by using simple chemical method. We have successfully obtained PbI2 material with purity higher than 85% and its crystal structure is comparable with that of commercial product. The perovskite CH3NH3PbI3 film was prepared by spin-coating of PbI2 solution and followed by spin-coating two-times of methylamonium iodide (MAI) solution. In this paper, the crystal structure of perovskite film attained from used car battery is shown and compared with that of prepared from commercial PbI2. By utilizing the used car battery into perovskite valuable material for high performance solar cells, we can not only improve the economical value (added-value) of wasted car battery but also we can simultaneously save the environment.

  5. Electrophoretic deposition of RuO2 /HRGO composites for flexible supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Amir, Fatima; Pham, Viet; Mullinax, Dakoda; Dickerson, James

    Flexible energy storage devices are essential for the development of wearable electronics, such as bendable displays and wearable multi-media systems. A subset of these energy storage devices, flexible supercapacitors have received increased attention because of their long cycle life, low cost, and easy fabrication. Herein, we report an easy and low cost method to fabricate bendable ruthenium oxide (RuO2) / holey reduced graphene oxide (HRGO) electrodes using electrophoretic deposition. Analysis of the surface morphology using scanning electron microscopy (SEM) shows a highly nanoporous structure with pores ranging from 2 to 3 nm. The obtained RuO2/HRGO supercapacitor exhibited excellent electrochemical capacitive performance in a PVA-H2SO4 gel electrolyte, with a specific capacitance of 418.5F/g. Additionally, a high rate performance with capacitance retention of 85% was observed when the current was increased by a factor of 20 from 1.0 to 20.0 A/g. The supercapacitor exhibited an exceptional cycling stability of 88.5% after 10,000 cycles, indicating excellent long term electrochemical stability.

  6. Highly sensitive and selective determination of methylergometrine maleate using carbon nanofibers/silver nanoparticles composite modified carbon paste electrode.

    PubMed

    Kalambate, Pramod K; Rawool, Chaitali R; Karna, Shashi P; Srivastava, Ashwini K

    2016-12-01

    A highly sensitive and selective voltammetric method for determination of Methylergometrine maleate (MM) in pharmaceutical formulations, urine and blood serum samples has been developed based on enhanced electrochemical response of MM at carbon nanofibers and silver nanoparticles modified carbon paste electrode (CNF-AgNP-CPE). The electrode material was characterized by various techniques viz., X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. The electrocatalytic response of MM at CNF-AgNP-CPE was studied by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). Under optimized conditions, the proposed sensor exhibits excellent electrochemical response towards MM. The DPV study shows greatly enhanced electrochemical signal for MM at CNF-AgNP-CPE lending high sensitivity to the proposed sensor for MM detection. The peak (Ip) current for MM is found to be rectilinear in the range 4.0×10(-8)-2.0×10(-5)M with a detection limit of 7.1×10(-9)M using DPV. The feasibility of the proposed sensor in analytical applications was investigated by conducting experiments on commercial pharmaceutical formulations, human urine and blood serum samples, which yielded satisfactory recoveries of MM. The proposed electrochemical sensor offers high sensitivity, selectivity, reproducibility and practical utility. We recommend it as an authentic and productive electrochemical sensor for successful determination of MM. PMID:27612735

  7. Application of infrared spectroscopy to monitoring gas insulated high-voltage equipment: electrode material-dependent SF(6) decomposition.

    PubMed

    Kurte, R; Beyer, C; Heise, H M; Klockow, D

    2002-08-01

    Sulfur hexafluoride is a chemically inert gas which is used in gas insulated substations (GIS) and other high-voltage equipment, leading to a significant enhancement of apparatus lifetime and reductions in installation size and maintenance requirements compared to conventional air insulated substations. However, component failures due to aging of the gas through electrical discharges may occur, and on-site monitoring for risk assessment is needed. Infrared spectroscopy was used for the analysis of gaseous by-products generated from electrical discharges in sulfur hexafluoride gas. An infrared monitoring system was developed using a micro-cell coupled to an FTIR spectrometer by silver halide fibers. Partial least-squares calibration was applied by using a limited number of optimally selected spectral variables. Emphasis was placed on the determination of main decomposition products, such as SOF(2), SOF(4), and SO(2)F(2). Besides the different electrical conditions, the material of the plane counter electrode of the discharge chamber was also varied between silver, aluminum, copper, tungsten, or tungsten/copper alloy. For the spark experiments the point electrode was the same material as chosen for the plane electrode, whereas for partial discharges a stainless steel needle was employed. Complementary investigations on the chemical composition within the solid counter electrode material by secondary neutral mass spectrometry (SNMS) were also carried out. Under sparking conditions, the electrode material plays an important role in the decomposition rates of the gas-phase, but no relevant material dependence could be observed under partial discharge conditions. PMID:12185577

  8. 25th anniversary article: polymer-particle composites: phase stability and applications in electrochemical energy storage.

    PubMed

    Srivastava, Samanvaya; Schaefer, Jennifer L; Yang, Zichao; Tu, Zhengyuan; Archer, Lynden A

    2014-01-15

    Polymer-particle composites are used in virtually every field of technology. When the particles approach nanometer dimensions, large interfacial regions are created. In favorable situations, the spatial distribution of these interfaces can be controlled to create new hybrid materials with physical and transport properties inaccessible in their constituents or poorly prepared mixtures. This review surveys progress in the last decade in understanding phase behavior, structure, and properties of nanoparticle-polymer composites. The review takes a decidedly polymers perspective and explores how physical and chemical approaches may be employed to create hybrids with controlled distribution of particles. Applications are studied in two contexts of contemporary interest: battery electrolytes and electrodes. In the former, the role of dispersed and aggregated particles on ion-transport is considered. In the latter, the polymer is employed in such small quantities that it has been historically given titles such as binder and carbon precursor that underscore its perceived secondary role. Considering the myriad functions the binder plays in an electrode, it is surprising that highly filled composites have not received more attention. Opportunities in this and related areas are highlighted where recent advances in synthesis and polymer science are inspiring new approaches, and where newcomers to the field could make important contributions. PMID:24323839

  9. Enhanced Electrocatalytic Performance of a Porous g-C3 N4 /Graphene Composite as a Counter Electrode for Dye-Sensitized Solar Cells.

    PubMed

    Wang, Guiqiang; Zhang, Juan; Kuang, Shuai; Zhang, Wei

    2016-08-01

    A porous graphitic carbon nitride (g-C3 N4 )/graphene composite was prepared by a simple hydrothermal method and explored as the counter electrode of dye-sensitized solar cells (DSCs). The obtained g-C3 N4 /graphene composite was characterized by XRD, SEM, TEM, FTIR spectroscopy, and X-ray photoelectron spectroscopy. The results show that incorporating graphene nanosheets into g-C3 N4 forms a three-dimensional architecture with a high surface area, porous structure, efficient electron-transport network, and fast charge-transfer kinetics at the g-C3 N4 /graphene interfaces. These properties result in more electrocatalytic active sites and facilitate electrolyte diffusion and electron transport in the porous framework. As a result, the as-prepared porous g-C3 N4 /graphene composite exhibits an excellent electrocatalytic activity. In I(-) /I3 (-) redox electrolyte, the charge-transfer resistance of the porous g-C3 N4 /graphene composite electrode is 1.8 Ω cm(2) , which is much lower than those of individual g-C3 N4 (70.1 Ω cm(2) ) and graphene (32.4 Ω cm(2) ) electrodes. This enhanced electrocatalytic performance is beneficial for improving the photovoltaic performance of DSCs. By employing the porous g-C3 N4 /graphene composite as the counter electrode, the DSC achieves a conversion efficiency of 7.13 %. This efficiency is comparable to 7.37 % for a cell with a platinum counter electrode. PMID:27381049

  10. Thickness Dependence and Percolation Scaling of Hydrogen Production Rate in MoS2 Nanosheet and Nanosheet-Carbon Nanotube Composite Catalytic Electrodes.

    PubMed

    McAteer, David; Gholamvand, Zahra; McEvoy, Niall; Harvey, Andrew; O'Malley, Eoghan; Duesberg, Georg S; Coleman, Jonathan N

    2016-01-26

    Here we demonstrate that the performance of catalytic electrodes, fabricated from liquid exfoliated MoS2 nanosheets, can be optimized by maximizing the electrode thickness coupled with the addition of carbon nanotubes. We find the current, and so the H2 generation rate, at a given potential to increase linearly with electrode thickness to up ∼5 μm after which saturation occurs. This linear increase is consistent with a simple model which allows a figure of merit to be extracted. The magnitude of this figure of merit implies that approximately two-thirds of the possible catalytically active edge sites in this MoS2 are inactive. We propose the saturation in current to be partly due to limitations associated with transporting charge through the resistive electrode to active sites. We resolve this by fabricating composite electrodes of MoS2 nanosheets mixed with carbon nanotubes. We find both the electrode conductivity and the catalytic current at a given potential to increase with nanotube content as described by percolation theory. PMID:26646693

  11. Carbon fiber reinforced thermoplastic composites for future automotive applications

    NASA Astrophysics Data System (ADS)

    Friedrich, K.

    2016-05-01

    After a brief introduction to polymer composite properties and markets, the state of the art activities in the field of manufacturing of advanced composites for automotive applications are elucidated. These include (a) long fiber reinforced thermoplastics (LFT) for secondary automotive components, and (b) continuous carbon fiber reinforced thermosetting composites for car body applications. It is followed by future possibilities of carbon fiber reinforced thermoplastic composites for e.g. (i) crash elements, (ii) racing car seats, and (iii) production and recycling of automotive fenders.

  12. Graphene, conducting polymer and their composites as transparent and current spreading electrode in GaN solar cells

    NASA Astrophysics Data System (ADS)

    Mahala, Pramila; Kumar, Ajay; Nayak, Sasmita; Behura, Sanjay; Dhanavantri, Chenna; Jani, Omkar

    2016-04-01

    Understanding the physics of charge carrier transport at graphene/p-GaN interface is critical for achieving efficient device functionality. Currently, the graphene/p-GaN interface is being explored as light emitting diodes, however this interface can be probed as a potential photovoltaic cell. We report the intimate interfacing of mechanically exfoliated graphene (EG), conducting polymer (PEDOT:PSS) and composite of reduced graphene oxide (rGO) and PEDOT:PSS with a wide band gap p-GaN layer. To explore their potential in energy harvesting, three heterojunction devices such as: (i) EG/p-GaN/sapphire, (ii) PEDOT:PSS/p-GaN/sapphire and (iii) PEDOT:PSS(rGO)/p-GaN/sapphire are designed and their photovoltaic characteristics are examined. It is interesting to observe that the EG/p-GaN/sapphire solar cell exhibits high open-circuit voltage of 0.545 V with low ideality factor and reverse saturation current. However, improved short circuit current density (13.7 mA/cm2) is noticed for PEDOT:PSS/p-GaN/sapphire solar cell because of enhanced conductivity accompanied by high transmittance for PEDOT:PSS. Further, the low series resistance for PEDOT:PSS(rGO)/p-GaN/sapphire is observed suggesting that the PEDOT:PSS and rGO composite is well dispersed and exhibits low interfacial resistances with p-GaN. The present investigation leverages the potential of graphene, conducting polymer and their composites as dual capability of (a) transparent and current spreading electrode and (b) an active top layer to make an intimate contact with wide bandgap p-type GaN for possible prospect towards high performance diodes, switches and solar cells.

  13. Effect of compounding process on the structure and electrochemical properties of ordered mesoporous carbon/polyaniline composites as electrodes for supercapacitors

    NASA Astrophysics Data System (ADS)

    Li, Lixia; Song, Huaihe; Zhang, Qincang; Yao, Jingyuan; Chen, Xiaohong

    Polyaniline (PANI) loaded ordered mesoporous carbon (OMC) composites were prepared via different processes, involving the in situ polymerization of aniline in the presence of OMC or its precursor and the direct physical mixing method. On the basis of analyzing the morphologies and structures of these three OMC/PANI composites, the influence of compounding processes on the electrochemical properties as electrodes for supercapacitors was first investigated. It was observed that regardless of compounding process, two distinct electrochemical behaviors took place on all of the composite electrodes, including a redox reaction with insertion and deinsertion of electrolyte ions, and electrostatic attraction at the electrode/electrolyte interface. Additionally, these OMC/PANI composites showed higher specific capacitances compared with pure OMC and PANI. Most significantly, the in situ synthesized OMC/PANI composite using OMC as a starting material exhibited the highest specific capacitance of 747 F g -1 at a current density of 0.1 A g -1 and excellent rate capability, which was attributed to the high degree of dispersion of PANI and the contact of PANI with electrolyte as well as the double fixing effects of surface and mesopore of OMC on PANI.

  14. Effects of concentration-dependent elastic modulus on Li-ions diffusion and diffusion-induced stresses in spherical composition-gradient electrodes

    SciTech Connect

    Zhang, Kai; Li, Yong; Zheng, Bailin

    2015-09-14

    The composition-gradient electrode material is considered as one of the most promising materials for lithium-ion batteries because of its excellent electrochemical performance and thermal stability. In this work, the effects of concentration-dependent elastic modulus on Li-ions diffusion and diffusion-induce stress in the composition-gradient electrodes were studied. The coupling equations of elasticity and diffusion under both potentiostatic charging and galvanostatic charging were developed to obtain the distributions of both the Li-ions concentration and the stress. The results indicated that the effects of the concentration-dependent elastic modulus on the Li-ions diffusion and the diffusion-induce stresses are controlled by the lithiation induced stiffening factor in the composition-gradient electrodes: a low stiffening factor at the center and a high stiffening factor at the surface lead to a significant effect, whereas a high stiffening factor at the center and a low stiffening factor at the surface result in a minimal effect. The results in this work provide guidance for the selection of electrode materials.

  15. Effects of concentration-dependent elastic modulus on Li-ions diffusion and diffusion-induced stresses in spherical composition-gradient electrodes

    NASA Astrophysics Data System (ADS)

    Zhang, Kai; Li, Yong; Zheng, Bailin

    2015-09-01

    The composition-gradient electrode material is considered as one of the most promising materials for lithium-ion batteries because of its excellent electrochemical performance and thermal stability. In this work, the effects of concentration-dependent elastic modulus on Li-ions diffusion and diffusion-induce stress in the composition-gradient electrodes were studied. The coupling equations of elasticity and diffusion under both potentiostatic charging and galvanostatic charging were developed to obtain the distributions of both the Li-ions concentration and the stress. The results indicated that the effects of the concentration-dependent elastic modulus on the Li-ions diffusion and the diffusion-induce stresses are controlled by the lithiation induced stiffening factor in the composition-gradient electrodes: a low stiffening factor at the center and a high stiffening factor at the surface lead to a significant effect, whereas a high stiffening factor at the center and a low stiffening factor at the surface result in a minimal effect. The results in this work provide guidance for the selection of electrode materials.

  16. Design, simulation and characterization of a MEMS inertia switch with flexible CNTs/Cu composite array layer between electrodes for prolonging contact time

    NASA Astrophysics Data System (ADS)

    Wang, Yang; Yang, Zhuoqing; Xu, Qiu; Chen, Wenguo; Ding, Guifu; Zhao, Xiaolin

    2015-08-01

    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.

  17. Graphene/polyaniline woven fabric composite films as flexible supercapacitor electrodes

    NASA Astrophysics Data System (ADS)

    Zang, Xiaobei; Li, Xiao; Zhu, Miao; Li, Xinming; Zhen, Zhen; He, Yijia; Wang, Kunlin; Wei, Jinquan; Kang, Feiyu; Zhu, Hongwei

    2015-04-01

    We report the design and preparation of graphene and polyaniline (PANI) woven-fabric composite films by in situ electropolymerization. The introduction of PANI greatly improves the electrochemical properties of solid-state supercapacitors which possess capacitances as high as 23 mF cm-2, and exhibit excellent cycling stability with ~100% capacitance retention after 2000 cycles. The devices have displayed superior flexibility with improved areal specific capacitances to 118% during deformation.We report the design and preparation of graphene and polyaniline (PANI) woven-fabric composite films by in situ electropolymerization. The introduction of PANI greatly improves the electrochemical properties of solid-state supercapacitors which possess capacitances as high as 23 mF cm-2, and exhibit excellent cycling stability with ~100% capacitance retention after 2000 cycles. The devices have displayed superior flexibility with improved areal specific capacitances to 118% during deformation. Electronic supplementary information (ESI) available: SEM image, Raman spectrum and electrochemical characterizations. See DOI: 10.1039/c5nr00584a

  18. Parasitic Absorption Reduction in Metal Oxide-Based Transparent Electrodes: Application in Perovskite Solar Cells.

    PubMed

    Werner, Jérémie; Geissbühler, Jonas; Dabirian, Ali; Nicolay, Sylvain; Morales-Masis, Monica; Wolf, Stefaan De; Niesen, Bjoern; Ballif, Christophe

    2016-07-13

    Transition metal oxides (TMOs) are commonly used in a wide spectrum of device applications, thanks to their interesting electronic, photochromic, and electrochromic properties. Their environmental sensitivity, exploited for gas and chemical sensors, is however undesirable for application in optoelectronic devices, where TMOs are used as charge injection or extraction layers. In this work, we first study the coloration of molybdenum and tungsten oxide layers, induced by thermal annealing, Ar plasma exposure, or transparent conducting oxide overlayer deposition, typically used in solar cell fabrication. We then propose a discoloration method based on an oxidizing CO2 plasma treatment, which allows for a complete bleaching of colored TMO films and prevents any subsequent recoloration during following cell processing steps. Then, we show that tungsten oxide is intrinsically more resilient to damage induced by Ar plasma exposure as compared to the commonly used molybdenum oxide. Finally, we show that parasitic absorption in TMO-based transparent electrodes, as used for semitransparent perovskite solar cells, silicon heterojunction solar cells, or perovskite/silicon tandem solar cells, can be drastically reduced by replacing molybdenum oxide with tungsten oxide and by applying a CO2 plasma pretreatment prior to the transparent conductive oxide overlayer deposition. PMID:27338079

  19. Ionic conductivity of stabilized zirconia networks in compositeSOFC electrodes

    SciTech Connect

    Yamahara, Keiji; Sholklapper, Tal Z.; Jacobson, Craig P.; Visco,Steven J.; De Jonghe, Lutgard C.

    2004-03-01

    The effective oxygen conductivities in the zirconia networks of porous LSM-YSZ and LSM-SYSZ composites [i.e. La0.85Sr0.15MnO3(Y2O3)0.08(ZrO2)0.92 and La0.85Sr0.15MnO3(c2O3)0.1(Y2O3)0.01(ZrO2)0.89,respectively] were evaluated by an AC impedance technique using specimens in which LSM was removed by hydrochloric acid leaching. The oxygen conductivities of porous YSZ and SYSZ alone followed a Koh-Fortini relationship. LSM-containing zirconia network conductivities were additionally decreased by the presence of the LSM, presumably by increased grain boundary resistances. Constriction resistances were estimated to have a minor effect.

  20. Tunable nanostructured composite with built-in metallic wire-grid electrode

    SciTech Connect

    Micheli, Davide Pastore, Roberto; Marchetti, Mario; Gradoni, Gabriele

    2013-11-15

    In this paper, the authors report an experimental demonstration of microwave reflection tuning in carbon nanostructure-based composites by means of an external voltage supplied to the material. DC bias voltages are imparted through a metal wire-grid. The magnitude of the reflection coefficient is measured upon oblique plane-wave incidence. Increasing the bias from 13 to 700 V results in a lowering of ∼20 dB, and a “blueshift” of ∼600 MHz of the material absorption resonance. Observed phenomena are ascribed to a change of the dielectric response of the carbon material. Inherently, the physical role of tunneling between nanofillers (carbon nanotubes) is discussed. Achievements aim at the realization of a tunable absorber. There are similar studies in literature that focus on tunable metamaterials operating at either optical or THz wavelengths.