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Sample records for platinum working electrode

  1. Platinum single crystal electrodes for the electrocatalysis of methane oxidation

    Directory of Open Access Journals (Sweden)

    Mayara Munaretto

    2011-03-01

    Full Text Available The main objective of this paper is to characterize the voltammetric profiles of platinum single crystals of low Miller indexes Pt(100 and Pt(110 and study their catalytic activities on the oxidation of methane. In this way, it was developed a metallic surface modified by presence of other metal oxide, which presents catalytic activity for this reaction. It is well known that the electrooxidation of methane (CH4 leads mainly to the formation of CO2 and H2O, however, the oxidation can also lead to the formation of CO, a reaction intermediate that has strong interaction with metal surfaces, such as platinum. This molecule tends to accumulate on the platinum surface and to passive it, due to the self-poisoning, decreasing its catalytic activity. Therefore, the main aim of this work was the development of a platinum electrode modified by deposition of titanium oxide, which presented electrocatalytic properties for the oxidation of methane.

  2. Strategies for the fabrication of porous platinum electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Kloke, Arne; Stetten, Felix von; Kerzenmacher, Sven [Laboratory for MEMS Applications, Department of Microsystems Engineering-IMTEK, University of Freiburg, Freiburg (Germany); Zengerle, Roland [Laboratory for MEMS Applications, Department of Microsystems Engineering-IMTEK, University of Freiburg, Freiburg (Germany); BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-Universitaet Freiburg (Germany)

    2011-11-16

    Porous platinum is of high technological importance due to its various applications in fuel cells, sensors, stimulation electrodes, mechanical actuators and catalysis in general. Based on a discussion of the general principles behind the reduction of platinum salts and corresponding deposition processes this article discusses techniques available for platinum electrode fabrication. The numerous, different strategies available to fabricate platinum electrodes are reviewed and discussed in the context of their tuning parameters, strengths and weaknesses. These strategies comprise bottom-up approaches as well as top-down approaches. In bottom-up approaches nanoparticles are synthesized in a first step by chemical, photochemical or sonochemical means followed by an electrode formation step by e.g. thin film technology or network formation to create a contiguous and conducting solid electrode structure. In top-down approaches fabrication starts with an already conductive electrode substrate. Corresponding strategies enable the fabrication of substrate-based electrodes by e.g. electrodeposition or the fabrication of self-supporting electrodes by dealloying. As a further top-down strategy, this review describes methods to decorate porous metals other than platinum with a surface layer of platinum. This way, fabrication methods not performable with platinum can be applied to the fabrication of platinum electrodes with the special benefit of low platinum consumption. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Nanostructured gold and platinum electrodes on silicon structures for biosensing

    International Nuclear Information System (INIS)

    Ogurtsov, V I; Sheehan, M M

    2005-01-01

    Gold and platinum metal electrodes on Si/SiO 2 having undergone anisotropic potassium hydroxide (KOH) etch treatment are considered. This treatment etches at different rates and directions in the material resulting in creation of numerous pyramid shaped holes in the silicon substrate. This surface is used to make metal electrodes with increased electrode efficiency. The electrodes can serve as the sensors or as the sensor substrates (for surface polymer modification) and because both gold and platinum are inert they have applications for food safety biosensing. Wine, an economically significant food product, was chosen as a matrix, and impedance spectroscopy (EIS) was selected as a method of investigation of electrode behaviour. Based on results of EIS, different complexity equivalent circuits were determined by applying fitting mean square root optimisation of sensor complex impedance measurements

  4. Platinum Porous Electrodes for Fuel Cells

    DEFF Research Database (Denmark)

    Andersen, Shuang Ma

    Fuel cell energy bears the merits of renewability, cleanness and high efficiency. Proton Exchange Membrane Fuel Cell (PEMFC) is one of the most promising candidates as the power source in the near future. A fine management of different transports and electrochemical reactions in PEM fuel cells...... to a genuine picture of a working PEM fuel cell catalyst layer. These, in turn, enrich the knowledge of Three-Phase-Boundary, provide efficient tool for the electrode selection and eventually will contribute the advancement of PEMFC technology....

  5. Reaction pathways for reduction of nitrate ions on platinum, rhodium, and platinum-rhodium alloy electrodes

    International Nuclear Information System (INIS)

    Cunha, M.C.P.M. da; De Souza, J.P.I.; Nart, F.C.

    2000-01-01

    The reduction of nitrate ions on platinum, rhodium, and platinum-rhodium alloy electrodes has been investigated using differential electrochemical mass spectrometry and in situ FTIR measurements. For 3 M HNO 3 concentration it has been found that nitrate starts the reduction with partial N-O bond dissociation and N-N bond formation generating NO and N 2 O. At potentials lower than 0.2 V the reaction proceeds forming dissolved NH 4 + . For potentials lower than 0 V the reduction continues via a multiple pathway reaction leading to the nonselective production of N 2 , NH 2 OH, and N 2 H 2 . On the alloyed electrodes, the production of NO and N 2 O has been observed in both cathodic and anodic scans, while on pure platinum and rhodium electrodes the reaction has been observed only during the cathodic scan. Contrasting with the pure platinum and rhodium alloys, where the N-O bond break starts forming NO and N 2 O, on the alloys HNO 2 has been observed as the first reaction step. For alloys with higher rhodium composition, like Pt 75 Rh 25 , no N 2 has been detected for potentials lower than 0 V

  6. Formic Acid Electrooxidation by a Platinum Nanotubule Array Electrode

    Directory of Open Access Journals (Sweden)

    Eric Broaddus

    2013-01-01

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

  7. The stability of PEMFC electrodes : platinum dissolution vs potential and temperature investigated by quartz crystal microbalance

    NARCIS (Netherlands)

    Dam, V.A.T.; Bruijn, de F.A.

    2007-01-01

    The stability of platinum in proton exchange membrane fuel cell (PEMFC) electrodes has been investigated by determining the dissolution of platinum from a thin platinum film deposited on a gold substrate in 1 M HClO4 at different temperatures ranging between 40 and 80°C and potentials between 0.85

  8. Electrosynthesis of vanillin from isoeugenol using platinum electrode

    Science.gov (United States)

    Mubarok, H.; Hilyatudini; Saepudin, E.; Ivandini, T. A.

    2017-04-01

    Vanillin was synthesized from isoeugenol through electrochemical method in one compartment cell using platinum electrode. Cyclic voltammetry in 0.1 M TBAP in methanol and acetonitrile indicated the first oxidation potential at +0.21 and +0.16 V (vs. Ag/AgCl), respectively. Isoeugenolis was proposed to undergo the oxidation accompanied by oxidative cleavage of alkene bond into aldehyde. Accordingly, the synthesis of vanillin was conducted using chronoamperometry technique. The electrosynthesis result was analyzed by HPLC and GC/MS. The optimum condition of the oxidation potential, solvent ratio, time of electrolysis and amount of water was investigated.

  9. Same-Side Platinum Electrodes for Metal Assisted Etching of Porous Silicon

    Science.gov (United States)

    2015-11-01

    Platinum Electrodes for Metal Assisted Etching of Porous Silicon by Matthew H Ervin and Brian Isaacson Sensors and Electron Devices Directorate...SUBTITLE Same-Side Platinum Electrodes for Metal Assisted Etching of Porous Silicon 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT

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

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  11. SFG study of platinum electrodes in perchloric acid solutions

    Science.gov (United States)

    Zheng, W. Q.; Pluchery, O.; Tadjeddine, A.

    2002-04-01

    Infrared-visible sum-frequency generation (SFG) spectroscopy has been used to study the structure of water molecules (and/or its derivatives OH -, H 3O + etc.) at aqueous electrolyte/electrode interfaces. For Pt(1 1 0) and Pt(1 0 0) electrodes in 0.1 M perchloric acid solution, we did not observe any significant O-H stretching resonance. In striking contrast to the resonant SFG signal, the nonresonant SFG (NRSFG) signal varies sensitively with the applied electrochemical potential, indicating that the interaction of water molecules with platinum electrodes is relatively weak as compared to that of H + and ClO 4- ions. From changes in the NRSFG signal and on the basis of an ionic adsorption model, we can also deduce that the potential of zero charge of Pt(1 1 0) in 0.1 M HClO 4 should be located at about 0.22 V (vs. NHE). This value is in good agreement with that measured recently by electrochemical method.

  12. Hydroxylamine electrochemistry at low-index single-crystal platinum electrodes in acidic media

    NARCIS (Netherlands)

    Rosca, V.; Beltramo, G.L.; Koper, M.T.M.

    2004-01-01

    The electrochemistry of hydroxylamine at low-index single-crystal platinum electrodes in acidic media has been studied by voltammetry and in-situ FTIRRAS. Hydroxylamine (HAM) reactivity at platinum is largely controlled by interaction of the other components of the solution or products of the HAM

  13. High Performance Platinum Group Metal Free Membrane Electrode Assemblies through Control of Interfacial Processes

    Energy Technology Data Exchange (ETDEWEB)

    Ayers, Katherine [Proton Energy Systems, Wallingford, CT (United States); Capuano, Christopher [Proton Energy Systems, Wallingford, CT (United States); Atanassov, Plamen [Univ. of New Mexico, Albuquerque, NM (United States); Mukerjee, Sanjeev [Northeastern Univ., Boston, MA (United States); Hickner, Michael [Pennsylvania State Univ., University Park, PA (United States)

    2017-11-29

    The quantitative goal of this project was to produce a high-performance anion exchange membrane water electrolyzer (AEM-WE) completely free of platinum group metals (PGMs), which could operate for at least 500 hours with less than 50 microV/hour degradation, at 500 mA/cm2. To achieve this goal, work focused on the optimization of electrocatalyst conductivity, with dispersion and utilization in the membrane electrode assembly (MEA) improved through refinement of deposition techniques. Critical factors were also explored with significant work undertaken by Northeastern University to further understand catalyst-membrane-ionomer interfaces and how they differ from liquid electrolyte. Water management and optimal cell operational parameters were established through the design, fabrication, and test of a new test station at Proton specific for AEM evaluation. Additionally, AEM material stability and robustness at high potentials and gas evolution conditions were advanced at Penn State.

  14. Sculptured platinum nanowire counter electrodes for dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyeonseok [Department of Electrical Engineering, Pennsylvania State University, University Park 16802 (United States); Horn, Mark W., E-mail: MHorn@engr.psu.edu [Department of Engineering Science and Mechanics, Pennsylvania State University, University Park 16802-6812 (United States)

    2013-07-01

    Sculptured platinum nanowire thin films were formed by oblique angle electron beam evaporation with a 5° vapor incidence angle and incorporated as counter electrodes for dye-sensitized solar cells (DSSCs). For the comparison of the performance, bare fluorine doped tin oxide, planar Pt electrodes and counter electrodes treated with chloroplatinic acid were prepared. The sculptured Pt nanowire electrodes showed five times lower charge transfer resistance (0.121 [Ω∗cm{sup 2}]) than that of Pt planar electrode (0.578 [Ω∗cm{sup 2}]) and when the Pt nanowire electrodes are treated with an H{sub 2}PtCl{sub 6} solution have more than ten times lower charge transfer resistance (0.04025 [Ω∗cm{sup 2}]). Moreover, Pt nanowire films used as a counter electrode lead to enhancement in current density and efficiency in comparison with Pt planar counter electrodes. The conversion efficiency with planar electrodes was 5.1 [%] while the efficiency of DSSC with platinum nanowire counter electrodes reached to 5.63 [%] under AM 1.5 illumination. - Highlights: • Pt sculptured thin films (STFs) fabricated by electron beam evaporator. • The STFs featured higher roughness and lower charge transfer resistance. • Improved performance of dye-sensitized solar cells by Pt STFs counter electrodes.

  15. Characterization of Platinum Electrodes and In-situ Cell Confluency Measurement Based on Current Changes of Cell-Electrodes

    Directory of Open Access Journals (Sweden)

    Chin Fhong SOON

    2015-04-01

    Full Text Available This study aimed at the development of a biosensor to examine the growth confluency of human derived keratinocytes (HaCaT cell lines in-situ. The biosensor consists of a sputter- coated glass substrate with platinum patterns. Cells were grown on the conductive substrates and the confluency of the cells were monitored in-situ based on the conductivity changes of the substrates. Characterization of the cell proliferation and confluency were interrogated using electrical cell-substrate impedance sensing (ECIS techniques and current change of cells using a pico-ammeter. The investigation was followed by the electrical characterization of the platinum electrode (PE using a two probe I-V measurement system. The surface morphology of platinum electrodes were studied using an atomic force microscopy (AFM and the HaCaT cell morphology was studied using Field-Emission Scanning Electron Microscopy (FE-SEM. The microscopy results showed that the cells coupled and proliferated on the platinum electrodes. For monitoring the conductivity and impedance changes of the cell-electrode in-situ, the cover of a Petri dish was inserted with pogo pins to be in contact with the platinum electrodes. The impedance was sampled using the ECIS technique at a twenty-four hour interval. In our findings, the cell proliferation rate can be measured by observing the changes in capacitance or impedance measured at low ac frequencies ranged from 10 - 1 kHz. In good agreement, the current measured at micro-ampere range by the biosensor decreased as the cell coverage area increased over the time. Thus, the percent of cell confluence was shown inversely proportional to the current changes.

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

    DEFF Research Database (Denmark)

    Wang, D. H.; Kou, R.; Gil, M. P.

    2005-01-01

    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......Abstract: 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...

  17. Cyclic voltammetric investigations of microstructured and platinum-covered glassy carbon electrodes in contact with a polymer electrolyte membrane

    Energy Technology Data Exchange (ETDEWEB)

    Scherer, G G; Veziridis, Z; Staub, M [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Freimuth, H [Inst. fuer Mikrotechnik Mainz IMM, Mainz (Germany)

    1997-06-01

    Model gas diffusion electrodes were prepared by microstructuring glassy carbon surfaces with high aspect ratios and subsequent deposition of platinum. These electrodes were characterized by hydrogen under-potential deposition (H-upd) in contact with a polymer electrolyte membrane employing cyclic voltametry. H-upd was found on platinum areas not in direct contact to the solid electrolyte, as long as a continuous platinum-path existed. A carbon surface between platinum acts as barrier for H-upd. (author) 4 figs., 5 refs.

  18. Platinum and palladium alloys suitable as fuel cell electrodes

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention concerns electrode catalysts used in fuel cells, such as proton exchange membrane (PEM) fuel cells. The invention is related to the reduction of the noble metal content and the improvement of the catalytic efficiency by low level substitution of the noble metal to provide new...... and innovative catalyst compositions in fuel cell electrodes. The novel electrode catalysts of the invention comprise a noble metal selected from Pt and Pd alloyed with an alkaline earth metal....

  19. Platinum and palladium alloys suitable as fuel cell electrodes

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention concerns electrode catalysts used in fuel cells, such as proton exchange membrane (PEM) fuel cells. The invention is related to the reduction of the noble metal content and the improvement of the catalytic5 efficiency by low level substitution of the noble metal to provide new...... and innovative catalyst compositions in fuel cell electrodes. The novel electrode catalysts of the invention comprise a noble metal selected from Pt and Pd alloyed with a lanthanide metal....

  20. Platinum and Palladium Alloys Suitable as Fuel Cell Electrodes

    DEFF Research Database (Denmark)

    2011-01-01

    The present invention concerns electrode catalysts used in fuel cells, such as proton exchange membrane (PEM) fuel cells. The invention is related to the reduction of the noble metal content and the improvement of the catalytic efficiency by low level substitution of the noble metal to provide new...... and innovative catalyst compositions in fuel cell electrodes. The novel electrode catalysts of the invention comprise a noble metal selected from Pt, Pd and mixtures thereof alloyed with a further element selected from Sc, Y and La as well as any mixtures thereof, wherein said alloy is supported on a conductive...

  1. The impact of water concentration on the catalytic oxidation of ethanol on platinum electrode in concentrated phosphoric acid

    Energy Technology Data Exchange (ETDEWEB)

    Camargo, A.P.M.; Previdello, B.A.F.; Varela, H.; Gonzalez, E.R. [Instituto de Quimica de Sao Carlos, Universidade de Sao Paulo, C.P. 780, CEP 13560-970 Sao Carlos, SP (Brazil)

    2010-01-15

    The electro-oxidation of ethanol on platinum in phosphoric acid opens the door to promote the oxidation reaction at higher temperatures. However, the effect of the presence of water is not well understood. In this work, the electro-oxidation of ethanol on platinum was studied in concentrated phosphoric acid containing different concentrations of water at room temperature. The results show that effect of bulk water on the rate electro-oxidation is highest at 0.60 V and decreases for increasing potentials. This was suggested as due to the increasing formation of oxygenated species on the electrode surface with potential, which in turn is more efficient than the increase of water content in the electrolyte. Altogether, these results were interpreted as an evidence of a Langmuir-Hinshelwood step involving oxygenated species as one of the adsorbed partners. (author)

  2. Determination of uranium by controlled-potential coulometry with platinum electrode

    International Nuclear Information System (INIS)

    Eppis, M.R.; Adelfang, P.

    1990-01-01

    In this work it was investigated the process by which is possible to determine uranium by means of a controlled-potential coulometry with a platinum electrode, using a reversible method, in presence of Pu(III) or Fe(II), that permits to analyze uranium and plutonium jointly with the same work electrode. The method has been adapted to be used in a standard electrochemical cell, without any modification. The determination occurs in five stages: 1) Uranium and iron reduction, with an electrolysis at -250mV vs standard calomel electrode (S.C.E.). 2) Electrolysis at +200 mV vs S.C.E. to remove the hydrogen generated in the former stage. 3) Oxidation of U(IV) to U(VI) and Fe(II) to Fe(III) by an electrolysis at +650 mV vs S.C.E. 4) Reduction of Fe(III) to Fe(II) at +200 mV vs S.C.E. 5) A new oxidation of Fe(II) to Fe(III) at +650 mV vs S.C.E. By difference between the integrated charge in the steps 3) and 5), the integrated charge corresponding to the uranium oxidation is obtained. It was necessary to determine: a) the potential and the time that is necessary to apply to realize quantitative electrochemical reduction of uranium. b) the dependence of the U/Fe concentration ratios. c) the weight of U contained in the aliqout and its influence on the method. The accuracy and precision of the method was studied and results with a standard deviation of 0.03% was obtained. Moreover, the method presents the following advantages: a) it is possible to determine U and Pu on the same aliquot; b) the process is reversible; c) the use of mercury in glove-box is avoided. (Author) [es

  3. Fabrication and Optimization of a Nanoporous Platinum Electrode and a Non-enzymatic Glucose Micro-sensor on Silicon

    Directory of Open Access Journals (Sweden)

    Younghun Kim

    2008-10-01

    Full Text Available In this paper, optimal conditions for fabrication of nanoporous platinum (Pt were investigated in order to use it as a sensitive sensing electrode for silicon CMOS integrable non-enzymatic glucose micro-sensor applications. Applied charges, voltages, and temperatures were varied during the electroplating of Pt into the formed nonionic surfactant C16EO8 nano-scaled molds in order to fabricate nanoporous Pt electrodes with large surface roughness factor (RF, uniformity, and reproducibility. The fabricated nanoporous Pt electrodes were characterized using atomic force microscopy (AFM and electrochemical cyclic voltammograms. Optimal electroplating conditions were determined to be an applied charge of 35 mC/mm2, a voltage of -0.12 V, and a temperature of 25 °C, respectively. The optimized nanoporous Pt electrode had an electrochemical RF of 375 and excellent reproducibility. The optimized nanoporous Pt electrode was applied to fabricate non-enzymatic glucose micro-sensor with three electrode systems. The fabricated sensor had a size of 3 mm x 3 mm, air gap of 10 µm, working electrode (WE area of 4.4 mm2, and sensitivity of 37.5 µA•L/mmol•cm2. In addition, it showed large detection range from 0.05 to 30 mmolL-1 and stable recovery responsive to the step changes in glucose concentration.

  4. Electrochemical degradation of chlorobenzene on boron-doped diamond and platinum electrodes

    International Nuclear Information System (INIS)

    Liu Lei; Zhao Guohua; Wu Meifen; Lei Yanzhu; Geng Rong

    2009-01-01

    In this paper the electrochemical degradation of chlorobenzene (CB) was investigated on boron-doped diamond (BDD) and platinum (Pt) anodes, and the degradation kinetics on these two electrodes was compared. Compared with the total mineralization with a total organic carbon (TOC) removal of 85.2% in 6 h on Pt electrode, the TOC removal reached 94.3% on BDD electrode under the same operate condition. Accordingly, the mineralization current efficiency (MCE) during the mineralization on BDD electrode was higher than that on the Pt electrode. Besides TOC, the conversion of CB, the productions and decay of intermediates were also monitored. Kinetic study indicated that the decay of CB on BDD and Pt electrodes were both pseudo-first-order reactions, and the reaction rate constant (k s ) on BDD electrode was higher than that on Pt electrode. The different reaction mechanisms on the two electrodes were investigated by the variation of intermediates concentrations. Two different reaction pathways for the degradation of CB on BDD electrode and Pt electrode involving all these intermediates were proposed.

  5. Microstructure of thin film platinum electrodes on yttrium stabilized zirconia prepared by sputter deposition

    Energy Technology Data Exchange (ETDEWEB)

    Toghan, Arafat, E-mail: arafat.toghan@pci.uni-hannover.de [Institute of Physical Chemistry and Electrochemistry, Leibniz University of Hannover, Callinstrasse 3-3a, D-30167 Hannover (Germany); Khodari, M. [Chemistry Department, Faculty of Science, South Valley University, Qena, 83523 (Egypt); Steinbach, F.; Imbihl, R. [Institute of Physical Chemistry and Electrochemistry, Leibniz University of Hannover, Callinstrasse 3-3a, D-30167 Hannover (Germany)

    2011-09-01

    (111) oriented thin film Pt electrodes were prepared on single crystals of yttrium-stabilized zirconia (YSZ) by sputter deposition of platinum. The electrodes were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDX), atomic force microscopy (AFM) and by profilometry. SEM images of the as-sputtered platinum film show a compact amorphous Pt film covering uniformly the substrate. Upon annealing at 1123 K, gaps and pores at the interface develop leading to a partial dewetting of the Pt film. Increasing the annealing temperature to 1373 K transforms the polycrystalline Pt film into single crystalline grains exhibiting a (111) orientation towards the substrate.

  6. Platinum nanoparticles decorated dendrite-like gold nanostructure on glassy carbon electrodes for enhancing electrocatalysis performance to glucose oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Hongmei [Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Ministry-of-Education Key Laboratory for the Green Preparation and Application of Functional Materials, School of Materials Science and Engineering, Hubei University, No. 368 Youyi Avenue, Wuchang, Wuhan 430062 (China); Chang, Gang, E-mail: changgang@hubu.edu.cn [Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Ministry-of-Education Key Laboratory for the Green Preparation and Application of Functional Materials, School of Materials Science and Engineering, Hubei University, No. 368 Youyi Avenue, Wuchang, Wuhan 430062 (China); Lei, Ming [State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876 (China); He, Hanping [College of Chemistry and Chemical Engineer, Hubei University, Youyi Road 368, Wuchang, Wuhan, Hubei 430062 (China); Liu, Xiong; Shu, Honghui; Xia, Tiantian; Su, Jie [Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Ministry-of-Education Key Laboratory for the Green Preparation and Application of Functional Materials, School of Materials Science and Engineering, Hubei University, No. 368 Youyi Avenue, Wuchang, Wuhan 430062 (China); He, Yunbin, E-mail: ybhe@hubu.edu.cn [Hubei Collaborative Innovation Center for Advanced Organic Chemical Materials, Ministry-of-Education Key Laboratory for the Green Preparation and Application of Functional Materials, School of Materials Science and Engineering, Hubei University, No. 368 Youyi Avenue, Wuchang, Wuhan 430062 (China)

    2016-10-30

    Highlights: • Pt/DGNs/GC composites were obtained via a clean and facile method without any templates, surfactants, or stabilizers. • Controlling chemical reduction deposition time, the amount of platinum nanoparticles on Au surface could be regulated, which further tuned electrocatalytic properties toward glucose oxidation. • The obtained Pt/DGNs/GC composites with high electrochemical active surface area (ECSA) show superior electrocatalytic activity to glucose. • The sensor based on Pt/DGNs/GC exhibited excellent sensitivity, selectivity and stability for nonenzymatic glucose detection. - Abstract: Platinum nanoparticles decorated dendrite-like gold nanostructure, bimetal composite materials on glassy carbon electrode (Pt/DGNs/GC) for enhancing electrocatalysis to glucose oxidation was designed and successfully fabricated by a facile two-step deposition method without any templates, surfactants, or stabilizers. Dendrite-like gold nanostructure was firstly deposited on the GC electrode via the potentiostatic method, and then platinum nanoparticles were decorated on the surface of gold substrate through chemical reduction deposition. X-ray diffraction (XRD), field-emission scanning electron microscope (FE-SEM), energy-dispersive X-ray spectroscopy (EDS) were applied to characterize the evolution of morphology and structure of the as-prepared Pt/DGNs/GC. Based on electrochemical measurements such as cyclic voltammetry, linear voltammetry and chronoamperometry, Pt/DGNs/GC exhibited significantly enhanced electrocatalytic performance to glucose oxidation compared those of pure dendrite-like Au nanoparticles in our previous report. Controlling chemical reduction deposition time, the amount of platinum nanoparticles on Au surface could be regulated, which further tuned electrocatalytic properties toward glucose oxidation. The dendrite-like gold surface partially covered by platinum nanoparticles dramatically enhanced the electrocatalytic performance for the

  7. Reductions in Aprotic Media. I. Cathodic Reduction Limits in Acetonitrile at a Platinum Electrode.

    Science.gov (United States)

    1981-08-15

    specifically; (1) The difference in the effect of water on lithium solutions and tetraalkylammonium solutions, (2) the passivation of a platinum electrode...solutions. 5 EXPERIMENTAL Procedure for Controlled Potential Electrolysis The electrolyses were performed in a glass H-cell. The anode and cathode...fine porous glass frit from the Luggin section. The electrolyses were run in constant potential mode. After electrolysis, the catholyte was removed and

  8. Electrochemical polymerization of furfural on a platinum electrode in aqueous solutions of potassium biphthalate

    Directory of Open Access Journals (Sweden)

    Jorge Luiz Joaquim Hallal

    2005-03-01

    Full Text Available Three different electrochemical methods confirm the growth processes of polyfurfural on platinum electrodes in aqueous solutions. The electrochemical oxidative polymerization of furfural occurs only with 0.10 mol L-1 potassium biphthalate as the supporting electrolyte. Electrochemical and spectroscopic methods are employed to characterize the polymeric film produced. Based on spectroscopic data, a polymeric structure involving furfural and biphthalate anions is discussed.

  9. Study of dopamine reactivity on platinum single crystal electrode surfaces

    International Nuclear Information System (INIS)

    Chumillas, Sara; Figueiredo, Marta C.; Climent, Víctor; Feliu, Juan M.

    2013-01-01

    Dopamine is the biological molecule responsible, among other functions, of the heart beat and blood pressure regulation. Its loss, in the human body, can result in serious diseases such as Parkinson's, schizophrenia or depression. Structurally, this molecule belongs to the group of catecholamines, together with epinephrine (adrenaline) and norepinephrine (noradrenaline). The hydroquinone moiety of the molecule can be easily oxidized to quinone, rendering the electrochemical methods a convenient approach for the development of dopamine biosensors. The reactivity of similar aromatic molecules, such as catechol and hydroquinone, at well-ordered platinum surfaces, has recently been investigated in our group. In this paper, we extend these studies to the structurally related molecule dopamine. The study has been performed in neutral pH, since this is closer to the natural conditions for these molecules in biological media. Cyclic voltammetry and in situ infra-red spectroscopy have been combined to extract information about the behavior of this molecule on well-defined platinum surfaces. Dopamine appears to be electrochemically active and reveals interesting adsorption phenomena at low potentials (0.15–0.25 V vs RHE), sensitive to the single crystal orientation. The adsorption of dopamine on these surfaces is very strong, taking place at much lower potentials than the electron transfer from solution species. Specifically, the voltammetry of Pt(1 1 1) and Pt(1 0 0) in dopamine solutions shows an oxidation peak at potentials close to the onset of hydrogen evolution, which is related to the desorption of hydrogen and the adsorption of dopamine. On the other hand, adsorption on Pt(1 1 0) is irreversible and the surface appears totally blocked. Spectroscopic results indicate that dopamine is adsorbed flat on the surface. At potentials higher than 0.6 V vs RHE the three basal planes show a common redox process. The initial formation of the quinone moiety is followed by a

  10. Platinum porphyrins as ionophores in polymeric membrane electrodes

    DEFF Research Database (Denmark)

    Lvova, Larisa; Verrelli, Giorgio; Nardis, Sara

    2011-01-01

    A comparative study of Pt(II)- and Pt(IV)-porphyrins as novel ionophores for anion-selective polymeric membrane electrodes is performed. Polymeric membranes of different compositions, prepared by varying plasticizers, cationic and anionic additives and Pt porphyrins, have been examined...... within the electrode membranes, while those based on Pt(IV)TPPCl2 operate via a mixed mode carrier mechanism, evidencing also a partial reduction of the starting ionophore to Pt(II)TPP. Spectrophotometric measurements of thin polymeric films indicate that no spontaneous formation of hydroxide ion bridged...... porphyrin dimers occurs in the membrane plasticized both with high or low dielectric constant plasticizer, due to a low oxophilicity of central Pt. The computational study of various anion–Pt(IV)TPPCl2 complex formation by means of semi-empirical and density functional theory (DFT) methods revealed a good...

  11. Single crystal studies of platinum alloys for oxygen reduction electrodes

    DEFF Research Database (Denmark)

    Ulrikkeholm, Elisabeth Therese

    /Pt(111) in the following. The prepared alloys were investigate using Low Energy Electron Diffraction (LEED), Xray Photoelectron Spectroscopy (XPS), Ion Scattering Spectroscopy (ISS) and temperature Programmed Desorption (TPD). The LEED pattern indicated that the Y/Pt(111) sample had formed a 1...... peaks with a large shift towards lower temperatures. The change in desorption temperature was ∆T = −180°C for the Y/Pt(111) sample and ∆T = −200°C for the Gd/Pt(111) sample. The ORR activity was measured showing a large enhancement for both alloys. Angle resolved XPS performed on the samples after.......89×1.89 structure, and the Gd/Pt(111) sample has formed a 1.90×1.90 structure compared to pure platinum. From the XPS measurements, it is most likely that alloys with the Pt5Y and Pt5Gd stoichiometry have been formed. The reactivity of the surfaces were probed using TPD. These measurements showed sharp desorption...

  12. Electroactivity of tin modified platinum electrodes for ethanol electrooxidation

    Energy Technology Data Exchange (ETDEWEB)

    Simoes, F.C.; de Andrade, A.R.; Olivi, P. [Departamento de Quimica da Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, Av. Bandeirantes, Caixa Postal 3900, 14040-901 Ribeirao Preto, SP (Brazil); dos Anjos, D.M.; Vigier, F.; Leger, J.-M.; Hahn, F.; Coutanceau, C.; Kokoh, K.B. [Equipe Electrocatalyse, UMR 6503 CNRS, Universite de Poitiers, 40 Avenue du Recteur Pineau, 86022 Poitiers Cedex (France); Gonzalez, E.R.; Tremiliosi-Filho, G. [Instituto de Quimica de Sao Carlos, Universidade de Sao Paulo, Caixa Postal 780, 13560-970 Sao Carlos, SP (Brazil)

    2007-05-01

    Different electrochemical techniques like cyclic voltammetry and chronoamperometry and tests in a single direct ethanol fuel cell (DEFC) were used to evaluate the catalytic activity of various compositions of PtSn electrodes prepared by thermal decomposition for ethanol electrooxidation. This oxidation process was also investigated by in situ infrared reflectance spectroscopy to determine the presence of adsorbed intermediates. The experimental results showed that PtSn can oxidize ethanol mainly to acetaldehyde and acetic acid. Adsorbed CO was also found, which demonstrates that the rupture of the C-C bond in the ethanol molecule can also take place during the oxidation process. This intermediate species was oxidized to CO{sub 2} which was detected by IR spectroscopy and chromatography. With Pt{sub 90}Sn{sub 10}/C as anode catalyst, single DEFC tests carried out using MEAs with a geometric electrode area of 5 cm{sup 2} allowed to produce a power density of ca. 72 mW cm{sup -2} at 110 C. (author)

  13. Electrochemical behaviour of gamma hydroxybutyric acid at a platinum electrode in acidic medium

    International Nuclear Information System (INIS)

    Jiménez-Pérez, R.; Sevilla, J.M.; Pineda, T.; Blázquez, M.; González-Rodríguez, J.

    2013-01-01

    Highlights: • This is the first reported electrochemical study of the behaviour of GHB. • The first study of the interaction of GHB on solid electrodes. • The GHB oxidation process in platinum electrodes is a complex process. • Re-dissolution and reduction of Pt oxides and oxidation of the GHB OH group. • The oxidation process is also influenced by pH and GHB concentration. -- Abstract: The electrooxidation of gamma hydroxybutyric acid (GHB) on a polycrystalline platinum electrode is studied by cyclic voltammetry in acidic medium. Two oxidation peaks, A and B, are obtained in the positive scan within the potential range of the double layer region and of the platinum oxide region, respectively. In the negative going potential sweep an inverted oxidation peak with an onset partially overlapping with the tail of the cathodic peak for the reduction of the platinum oxide formed during the anodic scan is obtained (peak C). This inverted peak can be observed at a potential close to +0.2 V (vs Ag/AgCl at pH 2) and separated 0.4 and 0.8 V from the two other oxidation peaks obtained during the anodic scan and in such conditions that the surface is particularly activated to favour this electrochemical process. The response obtained in the electronic current for the different peaks when GHB concentration and scan rate were changed to allows inferring that these are the result of a potential dependent mechanism. The behaviour observed is according with the oxidation of the alcohol group to the corresponding aldehyde and carboxylic acid (succinic acid) as main products

  14. Experimental and theoretical studies on electropolymerization of polar amino acids on platinum electrode

    Energy Technology Data Exchange (ETDEWEB)

    Alhedabi, Taleb [Nanomedicine Lab EA4662, Bat. E, Université de Bourgogne Franche-Comté, UFR Sciences & Techniques, 16 route de Gray, 25030 Besançon Cedex (France); Department of Chemistry, College of Science, University of Thi-qar, Thi-qar (Iraq); Cattey, Hélène [Institut ICMUB - CNRS 6302, Université de Bourgogne Franche-Comté, UFR Sciences et Techniques Mirande, 9 Avenue Alain Savary, 21000 Dijon (France); Roussel, Christophe [Ecole Polytechnique Fédérale de Lausanne, Section of Chemistry and Chemical Engineering, Station 6, CH-1015 Lausanne (Switzerland); Blondeau-Patissier, Virginie [Institut FEMTO-ST, UMR CNRS 6174, Department Time-Frequency, 26, Chemin de l' épitaphe, 25030 Besançon Cedex (France); Gharbi, Tijani [Nanomedicine Lab EA4662, Bat. E, Université de Bourgogne Franche-Comté, UFR Sciences & Techniques, 16 route de Gray, 25030 Besançon Cedex (France); Herlem, Guillaume, E-mail: guillaume.herlem@univ-fcomte.fr [Nanomedicine Lab EA4662, Bat. E, Université de Bourgogne Franche-Comté, UFR Sciences & Techniques, 16 route de Gray, 25030 Besançon Cedex (France)

    2017-01-01

    The anodic oxidation of polar amino acids (L-serine, L-threonine, L-asparagine, and L-glutamine) in aqueous electrolyte on smooth platinum electrode was carried out by cyclic voltammetry coupled to electrochemical quartz crystal microbalance (EQCM). pH (zwitterion, acidic and alkaline) effects on their electrochemical behavior were examined. The maximum current values are measured for zwitterion species. In addition, the current increases with increasing of concentration and scan rate, and decreases with increasing pH. The resulting passivation was studied by spectroscopic analysis such as attenuated total reflection FT infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS) and mass spectroscopy (MALDI-TOF). From thin film coatings observed on the electrode surface, peptide bonds are found, and are in favor of electropolymerization of these polar amino acids into poly-L-amino acids in an irreversible way. Scanning electronic microscopy was also used to study the morphology of these electrodeposited L-amino acids. The electrodeposited poly-L-amino acids on Pt electrode were tested as bioinspired transducer for pH sensing purposes. - Highlights: • Anodic oxidation of polar amino acids with uncharged R group on platinum electrode. • Polypeptide bonds revealed by ATR-IR and XPS spectroscopies. • The film growth depends on the chemistry of the polar amino acid.

  15. Mechanical polishing as an improved surface treatment for platinum screen-printed electrodes

    Directory of Open Access Journals (Sweden)

    Junqiao Lee

    2016-07-01

    Full Text Available The viability of mechanical polishing as a surface pre-treatment method for commercially available platinum screen-printed electrodes (SPEs was investigated and compared to a range of other pre-treatment methods (UV-Ozone treatment, soaking in N,N-dimethylformamide, soaking and anodizing in aqueous NaOH solution, and ultrasonication in tetrahydrofuran. Conventional electrochemical activation of platinum SPEs in 0.5 M H2SO4 solution was ineffective for the removal of contaminants found to be passivating the screen-printed surfaces. However, mechanical polishing showed a significant improvement in hydrogen adsorption and in electrochemically active surface areas (probed by two different redox couples due to the effective removal of surface contaminants. Results are also presented that suggest that SPEs are highly susceptible to degradation by strong acidic or caustic solutions, and could potentially lead to instability in long-term applications due to continual etching of the binding materials. The ability of SPEs to be polished effectively extends the reusability of these traditionally “single-use” devices. Keywords: Screen-printed electrodes, Polishing, Platinum, Activation, Pre-treatment, Cyclic voltammetry

  16. Transparent platinum counter electrode for efficient semi-transparent dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Iefanova, Anastasiia; Nepal, Jeevan; Poudel, Prashant; Davoux, Daren; Gautam, Umesh [Electrical Engineering and Computer Science Department, South Dakota State University, Brookings, SD 57006 (United States); Mallam, Venkataiah [Chemistry and Biochemistry Department, South Dakota State University, Brookings, SD 57006 (United States); Qiao, Qiquan [Electrical Engineering and Computer Science Department, South Dakota State University, Brookings, SD 57006 (United States); Logue, Brian [Chemistry and Biochemistry Department, South Dakota State University, Brookings, SD 57006 (United States); Baroughi, Mahdi Farrokh, E-mail: m.farrokhbaroughi@sdstate.edu [Electrical Engineering and Computer Science Department, South Dakota State University, Brookings, SD 57006 (United States)

    2014-07-01

    A method for fabrication of highly transparent platinum counter electrodes (CEs) has been developed based on spray coating of Pt nanoparticles (NPs) on hot substrates. This method leads to 86% reduction in Pt consumption reducing the Pt cost per peak watt of counter electrode from $0.79/Wp down to $0.11/Wp compared to the conventional Pt counter electrodes made by sputter deposition. The simplicity and low cost of this method provide a basis for an up-scalable fabrication process. The Pt NP layer is over 88% transparent, leading to overall transparency of 80% when incorporated with indium tin oxide/glass substrates for functional counter electrodes. This counter electrode exhibits a large surface area and high catalytic activity, comparable to that of the conventional opaque CEs. Semi-transparent dye-sensitized solar cells fabricated based on this counter electrode showed 6.17% power conversion efficiency. - Highlights: • Counter electrode (CE) prepared by spraying nanoparticle (NP) Pt on hot substrate. • Low cost and scalable fabrication process of CE. • The spray deposited CE uses 10 times less Pt compared to the sputtering method. • The CE is 80% transparent and exhibits a large surface and high catalytic activity. • A semitransparent dye-sensitized solar cell with Pt NP CE was 6.17% efficient.

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

    Science.gov (United States)

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

    2014-07-01

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

  18. Improving Impedance of Implantable Microwire Multi-Electrode Arrays by Ultrasonic Electroplating of Durable Platinum Black

    Science.gov (United States)

    Desai, Sharanya Arcot; Rolston, John D.; Guo, Liang; Potter, Steve M.

    2010-01-01

    Implantable microelectrode arrays (MEAs) have been a boon for neural stimulation and recording experiments. Commercially available MEAs have high impedances, due to their low surface area and small tip diameters, which are suitable for recording single unit activity. Lowering the electrode impedance, but preserving the small diameter, would provide a number of advantages, including reduced stimulation voltages, reduced stimulation artifacts and improved signal-to-noise ratio. Impedance reductions can be achieved by electroplating the MEAs with platinum (Pt) black, which increases the surface area but has little effect on the physical extent of the electrodes. However, because of the low durability of Pt black plating, this method has not been popular for chronic use. Sonicoplating (i.e. electroplating under ultrasonic agitation) has been shown to improve the durability of Pt black on the base metals of macro-electrodes used for cyclic voltammetry. This method has not previously been characterized for MEAs used in chronic neural implants. We show here that sonicoplating can lower the impedances of microwire multi-electrode arrays (MMEA) by an order of magnitude or more (depending on the time and voltage of electroplating), with better durability compared to pulsed plating or traditional DC methods. We also show the improved stimulation and recording performance that can be achieved in an in vivo implantation study with the sonicoplated low-impedance MMEAs, compared to high-impedance unplated electrodes. PMID:20485478

  19. Dynamic environmental transmission electron microscopy observation of platinum electrode catalyst deactivation in a proton-exchange-membrane fuel cell.

    Science.gov (United States)

    Yoshida, Kenta; Xudong, Zhang; Bright, Alexander N; Saitoh, Koh; Tanaka, Nobuo

    2013-02-15

    Spherical-aberration-corrected environmental transmission electron microscopy (AC-ETEM) was applied to study the catalytic activity of platinum/amorphous carbon electrode catalysts in proton-exchange-membrane fuel cells (PEMFCs). These electrode catalysts were characterized in different atmospheres, such as hydrogen and air, and a conventional high vacuum of 10(-5) Pa. A high-speed charge coupled device camera was used to capture real-time movies to dynamically study the diffusion and reconstruction of nanoparticles with an information transfer down to 0.1 nm, a time resolution below 0.2 s and an acceleration voltage of 300 kV. With such high spatial and time resolution, AC-ETEM permits the visualization of surface-atom behaviour that dominates the coalescence and surface-reconstruction processes of the nanoparticles. To contribute to the development of robust PEMFC platinum/amorphous carbon electrode catalysts, the change in the specific surface area of platinum particles was evaluated in hydrogen and air atmospheres. The deactivation of such catalysts during cycle operation is a serious problem that must be resolved for the practical use of PEMFCs in real vehicles. In this paper, the mechanism for the deactivation of platinum/amorphous carbon electrode catalysts is discussed using the decay rate of the specific surface area of platinum particles, measured first in a vacuum and then in hydrogen and air atmospheres for comparison.

  20. Ligand substitution and selective surface coordination studies of iodine and 2,5-dihydroxythiophenol at platinum electrodes

    International Nuclear Information System (INIS)

    Berry, G.M.; Soriaga, M.P.

    1989-01-01

    The relative surface coordination strengths of 2,5-dihydroxythiophenol (DHT) and iodine at a smooth polycrystalline platinum electrode have been investigated by thin-layer electrochemical techniques. The competitive chemisorption was studied by exposing the Pt electrode to solutions of varying mole fractions of I and DHT. Studies of ligand substitution were carried out by the introduction of an iodine-coated Pt electrode into DHT solutions, and the introduction of a DHT-coated into I solutions. Surface coverage measurements indicated that DHT is preferentially adsorbed and will displace chemisorbed iodine at the Pt electrode. Chemisorbed DHT is not appreciably displaced by iodine. These results and their contribution to the trend in the selective surface coordination chemistry of platinum electrodes will be discussed

  1. Voltammetric Determination of Salbutamol Based on Electrochemical Oxidation at Platinum and Glassy Carbon Electrodes

    OpenAIRE

    YILMAZ, Niyazi; ÖZKAN, Sibel A.; USLU, Bengi

    2014-01-01

    The oxidative behavior of salbutamol was studied as a function of pH at platinum and activated glassy carbon electrodes. Between pH 1.9 and 12.0, the drug was characterized by a single oxidation step at both electrodes. The process was found to be dependent on the nature and the pH of the supporting elctrolyte. The procedure yielded a linear concentration range of 1 \\times 10-4 to 1 \\times 10-3 M and 2 \\times 10-5 to 1 \\times 10-3 M in 0.2 M sulphuric acid and a phosphate buffer of pH 6, at p...

  2. The effect of gamma radiation on reference electrodes and platinum and carbon steel bare metal electrodes in a simulated waste solution

    International Nuclear Information System (INIS)

    Danielson, M.J.

    1993-09-01

    Electrochemical potential measurements of materials in waste tanks are important in determining if the materials have a propensity for stress corrosion cracking and pitting. Potential measurement requires a reference electrode, but the effect of radiation on the potential generated by the reference electrode has been an unknown quantity. To determine the significance of the radiation effect, Pacific Northwest Laboratory conducted studies of five types of electrodes under gamma radiation at room temperature. The subjects were two types of silver/silver chloride reference electrodes (Fisher and Lazaran), a mercury/calomel reference electrode, a platinum ''flag,'' and a piece of A-537 carbon steel; the electrodes were exposed to a simulated caustic tank environment. The Fisher silver/silver chloride and mercury/calomel reference electrodes showed essentially no radiation effects up to a flux of 2.1E6 R/h and fluence of 9.4E8 R, indicating they would be useful reference electrodes for in-tank studies. The Lazaran reg-sign silver/silver chloride electrode showed serious potential deviations at fluences of 2.E8 R, but it would be the electrode of choice in many situations because it is simple to maintain. Radiation affected the open circuit potential of both the platinum and carbon steel electrodes. This effect indicates that corrosion studies without radiation may not duplicate the corrosion processes expected in a waste tank. Mixed-potential theory was used to explain the radiation effects

  3. Influence of Surface Adsorption on Work Function Measurements on Gold-Platinum Interface Using Scanning Kelvin Probe Microscopy

    International Nuclear Information System (INIS)

    Mugo, Simon; Yuan Jun

    2012-01-01

    Surface potential difference (SPD) on freshly coated gold and platinum electrodes have been found to be much smaller than bulk work functions consideration and to be dependent on time. We show these discrepancies arise due to formation of surface dipoles caused by adsorbed contaminants in ambient environments. The process is reversible by gentle annealing consistent with contaminant hypothesis. Examination of potential changes on individual electrodes suggest that the Pt surface is more sensitive to ambient conditions than the Au surface in accordance with their relative chemical activities. The result has great implication for interpretation of Kelvin probe measurements obtained on practical devices exposed to ambient environments.

  4. A phenyl-sulfonic acid anchored carbon-supported platinum catalyst for polymer electrolyte fuel cell electrodes

    International Nuclear Information System (INIS)

    Selvarani, G.; Sahu, A.K.; Choudhury, N.A.; Sridhar, P.; Pitchumani, S.; Shukla, A.K.

    2007-01-01

    A method, to anchor phenyl-sulfonic acid functional groups with the platinum catalyst supported onto a high surface-area carbon substrate, is reported. The use of the catalyst in the electrodes of a polymer electrolyte fuel cell (PEFC) helps enhancing its performance. Characterization of the catalyst by Fourier transform infra red (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and point-of-zero-charge (PZC) studies suggests that the improvement in performance of the PEFC is facilitated not only by enlarging the three-phase boundary in the catalyst layer but also by providing ionic-conduction paths as well as by imparting negative charge to platinum sites with concomitant oxidation of sulfur present in the carbon support. It is argued that the negatively charged platinum sites help repel water facilitating oxygen to access the catalyst sites. The PEFC with modified carbon-supported platinum catalyst electrodes exhibits 40% enhancement in its power density as compared to the one with unmodified carbon-supported platinum catalyst electrodes

  5. Cyclic voltammetric study of electro-oxidation of methanol on platinum electrode in acidic and neutral media

    International Nuclear Information System (INIS)

    Khan, A.S.A.; Ahmed, R.; Mirza, M.L.

    2007-01-01

    The electro-oxidation of methanol on electrochemically treated platinum foil was investigated in acidic and neutral media for comparison of cyclic voltammetric characteristics and elucidation of mechanism of electro-oxidation of methanol. The surface area and roughness factor of platinum electrode was calculated. The electro-oxidation of mathanol is an irreversible process giving. anodic peaks in both anodic and cathodic sweep. The characteristic peaks of electrooxidation of methanol appeared at almost the same potential region in both acidic and neutral media. In neutral medium, certain additional cathodic/anodic peaks appeared which were confirmed to arise by the reduction/oxidation of hydrogen ions. The exchange current density and heterogeneous electron transfer rate constant was higher in neutral medium as. compared with acidic medium. The thermodynamic parameters delta H, delta S, and delta G/sub 298/ were calculated. The values of delta H and delta G/sub 298/were positive which indicated that the process of electro-oxidation of methanol is an endothermic and nonspontaneous. The mechanism of electro-oxidation of methanol was same in both acidic and neutral media involving the formation of various adsorbed intermediate species through dissociative adsorption steps leading to the formation of Co adsorbed radicals, which are removed. during interaction with adsorbed hydrous oxides provided by the oxidation of adsorbed water molecules. The higher rate of electro-oxidation of methanol in neutral medium was interpreted in the tight of electrochemical mechanism and was attributed to the presence of comparatively small amount of hydrogen ions only along the surface of working electrode, which are produced during electro-oxidation of methanol. (author)

  6. OXYGEN BUBBLE DEVELOPMENT ON A PLATINUM ELECTRODE IN BOROSILICATE GLASS MELT BY THE EFFECT OF ALTERNATING CURRENT

    Directory of Open Access Journals (Sweden)

    Jiri Matej

    2014-10-01

    or on alternating reduction and re-forming of oxidic layer on the electrode in the transition range, has been suggested. Start of bubble evolution at low alternating current density has also been observed in simple sodium-calcium-silicate glass melt. A relation between bubble release and platinum corrosion caused by reduced silicon has been suggested

  7. Surface structured platinum electrodes for the electrochemical reduction of carbon dioxide in imidazolium based ionic liquids.

    Science.gov (United States)

    Hanc-Scherer, Florin A; Montiel, Miguel A; Montiel, Vicente; Herrero, Enrique; Sánchez-Sánchez, Carlos M

    2015-10-07

    The direct CO2 electrochemical reduction on model platinum single crystal electrodes Pt(hkl) is studied in [C2mim(+)][NTf2(-)], a suitable room temperature ionic liquid (RTIL) medium due to its moderate viscosity, high CO2 solubility and conductivity. Single crystal electrodes represent the most convenient type of surface structured electrodes for studying the impact of RTIL ion adsorption on relevant electrocatalytic reactions, such as surface sensitive electrochemical CO2 reduction. We propose here based on cyclic voltammetry and in situ electrolysis measurements, for the first time, the formation of a stable adduct [C2mimH-CO2(-)] by a radical-radical coupling after the simultaneous reduction of CO2 and [C2mim(+)]. It means between the CO2 radical anion and the radical formed from the reduction of the cation [C2mim(+)] before forming the corresponding electrogenerated carbene. This is confirmed by the voltammetric study of a model imidazolium-2-carboxylate compound formed following the carbene pathway. The formation of that stable adduct [C2mimH-CO2(-)] blocks CO2 reduction after a single electron transfer and inhibits CO2 and imidazolium dimerization reactions. However, the electrochemical reduction of CO2 under those conditions provokes the electrochemical cathodic degradation of the imidazolium based RTIL. This important limitation in CO2 recycling by direct electrochemical reduction is overcome by adding a strong acid, [H(+)][NTf2(-)], into solution. Then, protons become preferentially adsorbed on the electrode surface by displacing the imidazolium cations and inhibiting their electrochemical reduction. This fact allows the surface sensitive electro-synthesis of HCOOH from CO2 reduction in [C2mim(+)][NTf2(-)], with Pt(110) being the most active electrode studied.

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

    Science.gov (United States)

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

    2016-01-01

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

  9. Effect of pH and Water Structure on the Oxygen Reduction Reaction on platinum electrodes

    International Nuclear Information System (INIS)

    Briega-Martos, Valentín; Herrero, Enrique; Feliu, Juan M.

    2017-01-01

    The oxygen reduction reaction (ORR) at different pH values has been studied at platinum single crystal electrodes using the hanging meniscus rotating disk electrode (HMRDE) configuration. The use of NaF/HClO 4 mixtures allows investigating the reaction up to pH = 6 in solutions with enough buffering capacity and in the absence of anion specific adsorption. The analysis of the currents shows that the kinetic current density measured at 0.85 V for the Pt(111) electrode follows a volcano curve with the maximum located around pH = 9. This maximum activity for pH = 9 can be related to the effects of the electrode charge and/or water structure in the ORR. On the other hand, the catalytic activity for the other basal planes shows a monotonic behavior with a small dependence of the activity with pH. For stepped surfaces with (111) terraces, the behavior with pH changes gets closer to that of the Pt(111) surface as the terrace length increases. Additionally, the ORR curves show a dependence of the limiting diffusion current with pH. It is observed that the limiting current density diminishes as the pH increases in a potential region where hydrogen peroxide is readily reduced. These results suggest the existence of a bifurcation point in the mechanism previous to peroxide formation, in which OOH • is proposed as the bifurcation intermediate. The reduction of OOH • requires proton addition and would be more difficult at neutral pH values, justifying the diminution of the limiting currents.

  10. Potentiometric sulfite biosensor based on entrapment of sulfite oxidase in a polypyrrole film on a platinum electrode modified with platinum nanoparticles

    International Nuclear Information System (INIS)

    Adeloju, Samuel B.; Hussain, Shahid

    2016-01-01

    The surface of a platinum electrode has been modified with platinum nanoparticles (PtNPs) and the enzyme sulfite oxidase (SOx), was entrapped on its surface in an ultrathin polypyrrole (PPy) film. The PtNPs, with a diameter of 30-40 nm, were deposited on the Pt electrode by cycling the electrode potential 20 times from -200 to 200 mV at a sweep rate of 50 mV.s"-"1. Morphological evidence of the successful incorporation of SOx and the presence of PtNPs were obtained by scanning electron microscopy. Also, the electrochemical behavior of the PtNPs/PPy-SOx film was examined by cyclic voltammetry, chronopotentiometry, electrochemical impedance spectroscopy and potentiometry. Under optimized conditions, the biosensor achieved a sensitivity of 57.5 mV.decade"-"1, a linear response that extends from 0.75 to 65 μM of sulfite, a detection limit of 12.4 nM, and a response time of 3-5 s. The biosensor was successfully applied to the determination of sulfite in wine and beer samples. (author)

  11. Glycolate adsorption at gold and platinum electrodes: A theoretical and in situ spectroelectrochemical study

    International Nuclear Information System (INIS)

    Delgado, Jose Manuel; Blanco, Raquel; Orts, Jose Manuel; Perez, Juan Manuel; Rodes, Antonio

    2010-01-01

    The adsorption of glycolate anions at sputtered gold thin-film electrodes was studied in perchloric acid solutions by cyclic voltammetry experiments combined with in situ Surface Enhanced Raman Scattering (SERS) and Surface Enhanced Infrared Reflection Absorption Spectroscopy under attenuated total reflection conditions (ATR-SEIRAS). Theoretical harmonic vibrational frequencies and band intensities obtained from B3LYP/LANL2DZ,6-31+G(d) calculations for glycolate species adsorbed on Au clusters with (1 1 1) orientation were used to interpret the experimental spectra. Vibrational data confirm the bidentate bonding of glycolate anions through the oxygen atoms of the carboxylate group, in a bridge configuration with the OCO plane perpendicular to the metal surface. The DFT calculations show no significant effect of the total charge of the metal cluster-adsorbate adduct on the vibrational frequencies of adsorbed glycolate species. The infrared experimental study is extended to platinum films electrochemically deposited onto sputtered gold thin-film electrodes showing the potential-dependent formation of adsorbed CO upon dissociative adsorption of glycolate anions. As in the case of gold, the reversible adsorption of glycolate anions takes place in a bidentate configuration as predicted by DFT calculations for glycolate adsorbed on Pt(1 1 1) clusters. At low glycolic acid concentration, the in situ ATR-SEIRA spectra evidence the formation of adsorbed oxalate as reaction intermediate.

  12. Electrochemical synthesis and spectroscopic characterization of poly(N-phenylpyrrole coatings in an organic medium on iron and platinum electrodes

    Directory of Open Access Journals (Sweden)

    A.K.D. Diaw

    2008-12-01

    Full Text Available The electrochemical synthesis of poly(N-phenylpyrrole film was achieved on pretreated iron and platinum electrodes in acetonitrile solutions containing 0.1 M N-phenylpyrrole as the monomer and 0.1 M tetrabutylammonium trifluoromethane sulfonate (Bu4NCF3SO3 as the supporting-salt. The results showed that a surface treatment by 10 % aqueous nitric acid inhibits iron dissolution without preventing the N-phenylpyrrole oxidation. Very strongly adherent films were obtained at constant-potential, constant-current and cyclic voltammetry. XPS measurements, infrared (FT-IR and electronic absorption (UV-vis spectroscopies were used to characterize the iron and platinum-coated electrodes. Finally the anticorrosion properties of the PΦP film were evidenced.

  13. Platinum/titanium bilayer deposited on polymer film as efficient counter electrodes for plastic dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Ikegami, M.; Miyoshi, K.; Miyasaka, T.; Teshima, K.; Wei, T. C.; Wan, C. C.; Wang, Y. Y.

    2007-01-01

    A surface-rich platinum/titanium bilayer was deposited on poly(ethylene naphthalate) film by vacuum sputtering as counterelectrode for plastic dye-sensitized solar cells (DSSCs). Compared to the electrodes made of pure Pt layer, this electrode maintained similar electrochemical catalytic effect at relative low Pt usage. Current-voltage characteristics of the plastic DSSC at this stage stand at 0.69 V on V OC , 9.97 mA/cm 2 on I SC , 0.69 on fill factor, and 4.31% cell efficiency under AM1.5, 100 mW/cm 2 illumination

  14. Electrochemical studies on the reduction of uranyl ions in nitric acid-hydrazine media at platinum electrode

    International Nuclear Information System (INIS)

    Mishra, Satyabrata; Sini, K.; Mallika, C.; Kamachi Mudali, U.; Jagadeeswara Rao, Ch.

    2015-01-01

    Production of uranous nitrate with good conversion efficiency is one of the major steps in the aqueous reprocessing of spent fuels of nuclear reactors, as U(IV) is used for the separation of Pu from U by the selective reduction of Pu(IV) into practically non-extractable Pu(III) in aqueous streams. Electro-reduction of uranyl ions has the advantage of not introducing corrosive chemicals into the process stream. High current efficiency with maximum conversion of U(VI) to U(IV) can be achieved in continuous as well as batch mode electro-reduction, if the process is voltage-controlled rather than current controlled. As potentiostatic studies reveal the mechanism of reduction of uranyl ions in potential controlled electrolysis, the reduction behavior of uranyl ions (UO 2 2+ ) in nitric acid and nitric acid-hydrazine media were investigated by Cyclic Voltammetric (CV) and Chronopotentiometric (CP) techniques using platinum working electrode at 298 K. Heterogeneous electron transfer rate constant (ks) for uranyl reduction was estimated at a very low concentration of nitric acid (0.05 M) using Klinger and Kochi equation. Values of the diffusion coefficients were determined as a function of acidity with and without hydrazine. Reduction of uranyl ions was found to be under kinetic as well as diffusion control when the concentration of nitric acid was 0.05 M and in the absence of hydrazine. However, as the acidity of the supporting electrolyte increased, the reduction was purely under kinetic control. (author)

  15. Multiple enhancement of luminol electrochemiluminescence using electrodes functionalized with titania nanotubes and platinum black: ultrasensitive determination of hydrogen peroxide, resveratrol, and dopamine

    International Nuclear Information System (INIS)

    Ming, Liang; Peng, Tingting; Tu, Yifeng

    2016-01-01

    We describe a substantial improvement of the electrochemiluminescence (ECL) of luminol which is widely used in flow injection analysis (FIA). It is based on synchronous dual sensitization of ECL by using titania nanotubes (TiNTs) and platinum black (PB). A piece of indium tin oxide (ITO) glass functionalized with TiNTs acts as the first working electrode, and a PB-modified platinum plate serves as the second one. By applying two constant potentials to the two electrodes, strong and consecutive ECL emission of luminol is obtained. The system works well in assays as shown for the successful quantitation of hydrogen peroxide (H 2 O 2 ), of the antioxidant resveratrol, and of the neutrotransmitter dopamine (DA) in spiked human serum samples. The detection limits for these three species (at a signal-to-noise ratio of 3) are as low as 66 pM (H 2 O 2 ), 22 nM (resveratrol), and 30 nM (DA). Recoveries in assays of DA in spiked serum range from 97.3 to 105.4 %. In our perception, the technique of dual sensitization represents a substantial improvement of the detection limits of ECL assays. (author)

  16. Dye sensitized solar cell based on platinum decorated multiwall carbon nanotubes as catalytic layer on the counter electrode

    International Nuclear Information System (INIS)

    Mathew, Ambily; Rao, G. Mohan; Munichandraiah, N.

    2011-01-01

    Graphical abstract: I-V characteristics of the DSSCs with Pt CE and Pt/MWCNT CE measured at 100 mW/cm 2 . It shows relatively better performance with Pt/MWCNT counter electrodes. Highlights: → Synthesis of multiwalled carbon nanotubes by pyrolysis. → Synthesis of Pt/MWCNT composite by chemical reduction. → Fabrication DSSC using Pt/MWCNT as catalytic layer on the counter electrode. → Study of catalytic activity by Electrochemical Impedance Spectroscopy. -- Abstract: In this study we have employed multiwall carbon nanotubes (MWCNT), decorated with platinum as catalytic layer for the reduction of tri-iodide ions in dye sensitized solar cell (DSSC). MWCNTs have been prepared by a simple one step pyrolysis method using ferrocene as the catalyst and xylene as the carbon source. Platinum decorated MWCNTs have been prepared by chemical reduction method. The as prepared MWCNTs and Pt/MWCNTs have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In combination with a dye adsorbed TiO 2 photoanode and an organic liquid electrolyte, Pt/MWCNT composite showed an enhanced short circuit current density of 16.12 mA/cm 2 leading to a cell efficiency of 6.50% which is comparable to that of Platinum.

  17. Dye sensitized solar cell based on platinum decorated multiwall carbon nanotubes as catalytic layer on the counter electrode

    Energy Technology Data Exchange (ETDEWEB)

    Mathew, Ambily [Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore 560012 India (India); Rao, G. Mohan, E-mail: gmrao@isu.iisc.ernet.in [Department of Instrumentation and Applied Physics, Indian Institute of Science, Bangalore 560012 India (India); Munichandraiah, N. [Department of Inorgonic and Physical Chemistry, Indian Institute of Science, Bangalore 560012 India (India)

    2011-11-15

    Graphical abstract: I-V characteristics of the DSSCs with Pt CE and Pt/MWCNT CE measured at 100 mW/cm{sup 2}. It shows relatively better performance with Pt/MWCNT counter electrodes. Highlights: {yields} Synthesis of multiwalled carbon nanotubes by pyrolysis. {yields} Synthesis of Pt/MWCNT composite by chemical reduction. {yields} Fabrication DSSC using Pt/MWCNT as catalytic layer on the counter electrode. {yields} Study of catalytic activity by Electrochemical Impedance Spectroscopy. -- Abstract: In this study we have employed multiwall carbon nanotubes (MWCNT), decorated with platinum as catalytic layer for the reduction of tri-iodide ions in dye sensitized solar cell (DSSC). MWCNTs have been prepared by a simple one step pyrolysis method using ferrocene as the catalyst and xylene as the carbon source. Platinum decorated MWCNTs have been prepared by chemical reduction method. The as prepared MWCNTs and Pt/MWCNTs have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In combination with a dye adsorbed TiO{sub 2} photoanode and an organic liquid electrolyte, Pt/MWCNT composite showed an enhanced short circuit current density of 16.12 mA/cm{sup 2} leading to a cell efficiency of 6.50% which is comparable to that of Platinum.

  18. Steady-state oxidation of cholesterol catalyzed by cholesterol oxidase in lipid bilayer membranes on platinum electrodes

    International Nuclear Information System (INIS)

    Bokoch, Michael P.; Devadoss, Anando; Palencsar, Mariela S.; Burgess, James D.

    2004-01-01

    Cholesterol oxidase is immobilized in electrode-supported lipid bilayer membranes. Platinum electrodes are initially modified with a self-assembled monolayer of thiolipid. A vesicle fusion method is used to deposit an outer leaflet of phospholipids onto the thiolipid monolayer forming a thiolipid/lipid bilayer membrane on the electrode surface. Cholesterol oxidase spontaneously inserts into the electrode-supported lipid bilayer membrane from solution and is consequently immobilized to the electrode surface. Cholesterol partitions into the membrane from buffer solutions containing cyclodextrin. Cholesterol oxidase catalyzes the oxidation of cholesterol by molecular oxygen, forming hydrogen peroxide as a product. Amperometric detection of hydrogen peroxide for continuous solution flow experiments are presented, where flow was alternated between cholesterol solution and buffer containing no cholesterol. Steady-state anodic currents were observed during exposures of cholesterol solutions ranging in concentration from 10 to 1000 μM. These data are consistent with the Michaelis-Menten kinetic model for oxidation of cholesterol as catalyzed by cholesterol oxidase immobilized in the lipid bilayer membrane. The cholesterol detection limit is below 1 μM for cholesterol solution prepared in buffered cyclodextrin. The response of the electrodes to low density lipoprotein solutions is increased upon addition of cyclodextrin. Evidence for adsorption of low density lipoprotein to the electrode surface is presented

  19. Preparation and electrocatalytic activity of platinum nano-particles in electrodes of proton exchange membrane fuel cell; Preparation et activite electrocatalytique des nano-particules de platine dans les electrodes de piles a combustible a membrane echangeuse de protons

    Energy Technology Data Exchange (ETDEWEB)

    Antoine, Olivier

    1998-07-01

    This work treats of the basic study of the reactions taking place on platinum nano-particles inside the active layers of proton exchange membrane fuel cells (PEMFC): oxygen reduction and hydrogen oxidation, and of the applied study of a method for the in-situ preparation of these particles. The study of oxygen reduction completes the previous works by confirming the effect of the particles size on the reaction kinetics (optimum of mass activity towards 3 nm of diameter), by considering the effect of the temperature and of the substrate, and also by the study of H{sub 2}O{sub 2} production at the disc-ring electrode and the reaction mechanism using impedance spectroscopy measurements: like with massive platinum in acid environment, the Damjanovic mechanism is retained for the platinum nano-particles. Hydrogen oxidation is much faster and limited by gas diffusion, and thus is more difficult to study. This work required the use of sophisticated correction programs and of an original geometry (very thin active layer: L < 1 {mu}m) to show a clear effect of the particle size on the kinetics: the catalytic activity increases with the smallest particles. This study has also tried to precise the poorly known reaction mechanism: the Heyrovsky-Volmer mechanism has been retained but it needs to be confirmed. The optimization of the catalyst used requires 3 nm particles for a maximum oxygen reduction mass activity and mass percentages Pt/(Pt+C)30% in order to minimize the thickness of the active layer and the diffusion limitations. An original in-situ electrochemical method respecting these conditions has been developed. Starting from carbon impregnated with platinum salts, it allows the deposition of catalyst nano-particles on the carbon in Nafion. (J.S.)

  20. Nonenzymatic determination of glucose at near neutral pH values based on the use of nafion and platinum black coated microneedle electrode array.

    Science.gov (United States)

    Chinnadayyala, Somasekhar R; Park, Ilhwan; Cho, Sungbo

    2018-04-07

    The authors report on a microneedle-based amperometric nonenzymatic glucose sensor for painless and continuous monitoring of glucose. It consists of 3 × 5 sharp stainless steel microneedles micromachined from a stainless steel substrate. The microneedles are 600 and 100 μm in height and width, respectively. Nafion and platinum black were sequentially coated onto the tip of gold-coated microneedles and used for nonenzymatic (direct) sensing of glucose. Attractive features of the modified microneedle electrode include (a) a low working potential (+0.12 V vs. Ag/AgCl), (b) a linear response in the physiologically relevant range (1-40 mM), (c) a sensitivity as high as 175 μA mM -1  cm -2 , (d) a 23 μM detection limit, and (e) a response time of 2 s. The sensor also exhibits good reproducibility and stability. The sensor is selective for glucose even in the presence of 10-fold higher concentrations of ascorbic acid, lactic acid, dopamine, uric acid, and acetaminophen. Graphical abstract Schematic representation of the fabrication sequence for a nonenzymatic electrochemical glucose sensor using Nafion and platinum black coated microneedle electrode array. The sensor is based on measuring the faradaic current at +0.12 V vs. Ag/AgCl by the direct electrochemical oxidation of glucose to gluconic acid on the surface of a Pt black sensing layer.

  1. Electrochemical pulsed deposition of platinum nanoparticles on indium tin oxide/polyethylene terephthalate as a flexible counter electrode for dye-sensitized solar cells

    International Nuclear Information System (INIS)

    Wei, Yu-Hsuan; Chen, Chih-Sheng; Ma, Chen-Chi M.; Tsai, Chuen-Horng; Hsieh, Chien-Kuo

    2014-01-01

    In this study, a pulsed-mode electrochemical deposition (Pulse-ECD) technique was employed to deposit platinum nanoparticles (PtNPs) on the indium tin oxide/polyethylene terephthalate (ITO/PET) substrate as a flexible counter electrode for dye-sensitized solar cells (DSSCs). The characteristic properties of the Pulse-ECD PtNPs were prepared and compared to the traditional (electron beam) Pt film. The surface morphologies of the PtNPs were examined by field emission scanning electron microscopy (FE-SEM) and the atomic force microscope (AFM). The FE-SEM results showed that our PtNPs were deposited uniformly on the ITO/PET flexible substrates via the Pulse-ECD technique. The AFM results indicated that the surface roughness of the pulsed PtNPs influenced the power conversion efficiency (PCE) of DSSCs, due to the high specific surface area of PtNPs which enhanced the catalytic activities for the reduction (I 3 − to I − ) of redox electrolyte. In combination with a N719 dye-sensitized TiO 2 working electrode and an iodine-based electrolyte, the DSSCs with the PtNPs flexible counter electrode showed a PCE of 4.3% under the illumination of AM 1.5 (100 mW cm −2 ). The results demonstrated that the Pulse-ECD PtNPs are good candidate for flexible DSSCs. - Highlights: • We used indium tin oxide/polyethylene terephthalate as a flexible substrate. • We utilized pulse electrochemical deposition to deposit platinum nanoparticles. • We synthesized a flexible counter electrode for dye-sensitized solar cell (DSSC). • The power conversion efficiency of DSSC was measured to be 4.3%

  2. Mechanistic Switching by Hydronium Ion Activity for Hydrogen Evolution and Oxidation over Polycrystalline Platinum Disk and Platinum/Carbon Electrodes

    KAUST Repository

    Shinagawa, Tatsuya

    2014-07-22

    Fundamental electrochemical reactions, namely the hydrogen evolution reaction (HER) and the hydrogen oxidation reaction (HOR), are re-evaluated under various pH conditions over polycrystalline Pt disk electrodes and Pt/C electrodes to investigate the overpotential and Tafel relations. Kinetic trends are observed and can be classified into three pH regions: acidic (1-5), neutral (5-9), and alkaline (9-13). Under neutral conditions, in which H2O becomes the primary reactant, substantial overpotential, which is not affected by pH and the supporting electrolyte type, is required for electrocatalysis in both directions. This ion independence, including pH, suggests that HER/HOR performance under neutral conditions solely reflects the intrinsic electrocatalytic activity of Pt in the rate determining steps, which involve electron transfer with water molecules. A global picture of the HER/HOR, resulting from mechanistic switching accompanied by change in pH, is detailed.

  3. In vitro biocompatibility and electrical stability of thick-film platinum/gold alloy electrodes printed on alumina

    Science.gov (United States)

    Carnicer-Lombarte, Alejandro; Lancashire, Henry T.; Vanhoestenberghe, Anne

    2017-06-01

    Objective. High-density electrode arrays are a powerful tool in both clinical neuroscience and basic research. However, current manufacturing techniques require the use of specialised techniques and equipment, which are available to few labs. We have developed a high-density electrode array with customisable design, manufactured using simple printing techniques and with commercially available materials. Approach. Electrode arrays were manufactured by thick-film printing a platinum-gold alloy (Pt/Au) and an insulating dielectric on 96% alumina ceramic plates. Arrays were conditioned in serum and serum-free conditions, with and without 1 kHz, 200 µA, charge balanced stimulation for up to 21 d. Array biocompatibility was assessed using an extract assay and a PC-12 cell contact assay. Electrode impedance, charge storage capacity and charge injection capacity were before and after array conditioning. Main results. The manufactured Pt/Au electrodes have a highly porous surface and exhibit electrical properties comparable to arrays manufactured using alternative techniques. Materials used in array manufacture were found to be non-toxic to L929 fibroblasts by extract assay, and neuronal-like PC-12 cells adhered and extended neurites on the array surfaces. Arrays remained functional after long-term delivery of electrical pulses while exposed to protein-rich environments. Charge storage capacities and charge injection capacities increased following stimulation accounted for by an increase in surface index (real surface area) observed by vertical scanning interferometry. Further, we observed accumulation of proteins at the electrode sites following conditioning in the presence of serum. Significance. This study demonstrates the in vitro biocompatibility of commercially available thick-film printing materials. The printing technique is both simple and versatile, with layouts readily modified to produce customized electrode arrays. Thick-film electrode arrays are an

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

    Science.gov (United States)

    Siriviriyanun, Ampornphan; Imae, Toyoko

    2013-04-14

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

  5. Investigation of Electrochemically Deposited and Chemically Reduced Platinum Nanostructured Thin Films as Counter Electrodes in Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Chih-Hung Tsai

    2018-02-01

    Full Text Available In this paper, we demonstrated that platinum (Pt counter electrodes (CEs fabricated using electrochemical deposition and chemical reduction can replace conventional high-temperature thermally decomposed Pt electrodes. In this study, Pt electrodes were fabricated using thermal decomposition, electrochemical deposition, and chemical reduction, and the influence of the different Pt counter electrodes on the efficiency of the dye-sensitized solar cells (DSSCs was analyzed. The properties of the various Pt CEs were analyzed using scanning electron microscopy (SEM, surface area analysis, X-ray diffraction (XRD, electrochemical impedance spectroscopy (EIS, and cyclic voltammetry (CV. DSSCs with various Pt CEs were characterized using current density-voltage (J-V, incident photo-current conversion efficiency (IPCE, and EIS measurements. The results show that the power conversion efficiencies of these three types of DSSC devices were between 7.43% and 7.72%. The DSSCs based on the Pt electrode fabricated through electrochemical deposition exhibited the optimal power conversion efficiency. Because the processes of electrochemical deposition and chemical reduction do not require high-temperature sintering, these two methods are suitable for the fabrication of Pt on flexible plastic substrates.

  6. Robust high temperature oxygen sensor electrodes

    DEFF Research Database (Denmark)

    Lund, Anders

    Platinum is the most widely used material in high temperature oxygen sensor electrodes. However, platinum is expensive and the platinum electrode may, under certain conditions, suffer from poisoning, which is detrimental for an oxygen sensor. The objective of this thesis is to evaluate electrode...... materials as candidates for robust oxygen sensor electrodes. The present work focuses on characterising the electrochemical properties of a few electrode materials to understand which oxygen electrode processes are limiting for the response time of the sensor electrode. Three types of porous platinum......-Dansensor. The electrochemical properties of the electrodes were characterised by electrochemical impedance spectroscopy (EIS), and the structures were characterised by x-ray diffraction and electron microscopy. At an oxygen partial pressures of 0.2 bar, the response time of the sensor electrode was determined by oxygen...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-12-15

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

  8. Electrochemical deposition of gold-platinum alloy nanoparticles on an indium tin oxide electrode and their electrocatalytic applications

    Energy Technology Data Exchange (ETDEWEB)

    Song Yan; Ma Yuting; Wang Yuan [Department of Chemistry, Soochow University, Suzhou, Jiangsu 215123 (China); Di Junwei, E-mail: djw@suda.edu.c [Department of Chemistry, Soochow University, Suzhou, Jiangsu 215123 (China); Tu Yifeng [Department of Chemistry, Soochow University, Suzhou, Jiangsu 215123 (China)

    2010-07-01

    Gold-platinum (Au-Pt) hybrid nanoparticles (Au-PtNPs) were successfully deposited on an indium tin oxide (ITO) surface using a direct electrochemical method. The resulting nanoparticles were characterized by scanning electron microscopy (SEM), UV-vis spectroscopy, X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), and electrochemical methods. It was found that the size of the Au-PtNPs depends on the number of electrodeposition cycles. Au-PtNPs obtained by 20 electrodeposition cycles had a cauliflower-shaped structure with an average diameter of about 60 nm. These Au-PtNPs exhibited alloy properties. Electrochemical measurements showed that the charge transfer resistivity was significantly decreased for the Au-PtNPs/ITO electrode. Additionally, the Au-PtNPs displayed an electrocatalytic activity for nitrite oxidation and oxygen reduction. The Au-PtNPs/ITO electrodes reported herein could possibly be used as electrocatalysts and sensors.

  9. Electrochemical removal of hexavalent chromium from wastewater using Platinum-Iron/Iron-carbon nanotubes and bipolar Electrodes

    Directory of Open Access Journals (Sweden)

    Hoshyar Hossini

    2015-01-01

    Full Text Available Background: In recent decades, electrocoagulation (EC has engrossed much attention as an environmental-friendly and effectiveness process. In addition, the EC process is a potential suitable way for treatment of wastewater with concern to costs and environment. The object of this study was electrochemical evaluation of chromium removal from industrial wastewater using Platinum and carbon nanotubes electrodes. Materials and Methods: The effect of key variables including pH (3–9, hexavalent chromium concentration (50–300 mg/l, supporting electrolyte (NaCl, KCl, Na2CO3 and KNO3 and its dosage, Oxidation-Reduction variations, sludge generation rate and current density (2–20 mA/cm2 was determined. Results: Based on experimental data, optimum conditions were determined in 20, 120 min, pH 3, NaCl 0.5% and 100 mg/L initial concentration of chromium. Conclusions: Removal of hexavalent chromium from the wastewater could be successfully performanced using Platinum-Iron/Iron-carbon nanotubes and bipolar Electrodes.

  10. An aptasensor for voltammetric and impedimetric determination of cocaine based on a glassy carbon electrode modified with platinum nanoparticles and using rutin as a redox probe

    International Nuclear Information System (INIS)

    Roushani, Mahmoud; Shahdost-fard, Faezeh

    2016-01-01

    We describe a method for the determination of cocaine that is based on a glassy carbon electrode modified with a nanocomposite consisting of multiwalled carbon nanotubes, an ionic liquid, and chitosan. The electrode was made cocaine-responsive by immobilizing a cocaine-specific aptamer and platinum nanoparticles (PtNPs) on the modified electrode. The use of PtNPs resulted in the acceleration of the electron transfer kinetics of the reduction of the redox probe rutin and enhances sensitivity. The sensor, best operated at a working voltage of 260 mV vs. Ag/AgCl, has a linear response to cocaine in the 1 nM to 11 μM concentration range, and the detection limit is 100 pM (at an S/N ratio of 3). We think this strategy to represent a promising platform for the sensitive and selective determination of cocaine. The sensor is adequately stable and was successfully applied to the determination of cocaine in spiked serum. (author)

  11. Determining the platinum loading and distribution of industrial scale polymer electrolyte membrane fuel cell electrodes using low energy X-ray imaging

    DEFF Research Database (Denmark)

    Holst, T.; Vassiliev, Anton; Kerr, R.

    2014-01-01

    Low energy X-ray imaging (E <25 keV) is herein demonstrated to be a rapid, effective and non-destructive tool for the quantitative determination of the platinum loading and distribution over the entire geometric area of gas diffusion electrodes for polymer electrolyte membrane fuel cells. A linea...... of electrodes fabricated using an industrial spraying process. This technique proves to be an attractive option for the electrode performance study, the process optimization and quality control of electrode fabrication on an industrial scale....

  12. Investigation of nanoporous platinum thin films fabricated by reactive sputtering: Application as micro-SOFC electrode

    Science.gov (United States)

    Jung, WooChul; Kim, Jae Jin; Tuller, Harry L.

    2015-02-01

    Highly porous Pt thin films, with nano-scale porosity, were fabricated by reactive sputtering. The strategy involved deposition of thin film PtOx at room temperature, followed by the subsequent decomposition of the oxide by rapid heat treatment. The resulting films exhibited percolating Pt networks infiltrated with interconnected nanosized pores, critical for superior solid oxide fuel cell cathode performance. This approach is particularly attractive for micro-fabricated solid oxide fuel cells, since it enables fabrication of the entire cell stack (anode/electrolyte/cathode) within the sputtering chamber, without breaking vacuum. In this work, the morphological, crystallographic and chemical properties of the porous electrode were systematically varied by control of deposition conditions. Oxygen reduction reaction kinetics were investigated by means of electrochemical impedance spectroscopy, demonstrating the critical role of nano-pores in achieving satisfactory micro-SOFC cathode performance.

  13. A hybrid nanostructure of platinum-nanoparticles/graphitic-nanofibers as a three-dimensional counter electrode in dye-sensitized solar cells.

    Science.gov (United States)

    Hsieh, Chien-Kuo; Tsai, Ming-Chi; Su, Ching-Yuan; Wei, Sung-Yen; Yen, Ming-Yu; Ma, Chen-Chi M; Chen, Fu-Rong; Tsai, Chuen-Horng

    2011-11-07

    We directly synthesized a platinum-nanoparticles/graphitic-nanofibers (PtNPs/GNFs) hybrid nanostructure on FTO glass. We applied this structure as a three-dimensional counter electrode in dye-sensitized solar cells (DSSCs), and investigated the cells' photoconversion performance. This journal is © The Royal Society of Chemistry 2011

  14. Methanol oxidation at platinum electrodes in acid solution: comparison between model and real catalysts

    Directory of Open Access Journals (Sweden)

    A. V. TRIPKOVIC

    2006-12-01

    Full Text Available Methanol oxidation in acid solution was studied at platinum single crystals, Pt(hkl, as the model catalyst, and at nanostructural platinum supported on high surface area carbon, Pt/C, as the real catalyst. The linear extrapolation method was used to determine the beginning of hydroxyl anion adsorption. Structural sensitivity of the adsorption was proved and a correlation with the onset of the methanol oxidation current was established at all catalysts. Bisulfate and chloride anions were found to decrease the methanol oxidation rate, but probably did not influence the reaction parth. The specific activity for the reaction increased in the sequence Pt(110 < Pt/C < Pt(111, suggesting that the activity of the supported Pt catalyst can be correlated with the activities of the dominating crystal planes on its surface.

  15. Electrocatalytic oxidation of hydrogen peroxide on a platinum electrode in the imitation of oxidative drug metabolism of lidocaine.

    Science.gov (United States)

    Nouri-Nigjeh, Eslam; Bruins, Andries P; Bischoff, Rainer; Permentier, Hjalmar P

    2012-10-21

    Electrochemistry in combination with mass spectrometry has shown promise as a versatile technique not only in the analytical assessment of oxidative drug metabolism, but also for small-scale synthesis of drug metabolites. However, electrochemistry is generally limited to reactions initiated by direct electron transfer. In the case of substituted-aromatic compounds, oxidation proceeds through a Wheland-type intermediate where resonance stabilization of the positive charge determines the regioselectivity of the anodic substitution reaction, and hence limits the extent of generating drug metabolites in comparison with in vivo oxygen insertion reactions. In this study, we show that the electrocatalytic oxidation of hydrogen peroxide on a platinum electrode generates reactive oxygen species, presumably surface-bound platinum-oxo species, which are capable of oxygen insertion reactions in analogy to oxo-ferryl radical cations in the active site of Cytochrome P450. Electrochemical oxidation of lidocaine at constant potential in the presence of hydrogen peroxide produces both 3- and 4-hydroxylidocaine, suggesting reaction via an arene oxide rather than a Wheland-type intermediate. No benzylic hydroxylation was observed, thus freely diffusing radicals do not appear to be present. The results of the present study extend the possibilities of electrochemical imitation of oxidative drug metabolism to oxygen insertion reactions.

  16. Influence of solvent on the infared spectrum of carbon monoxide adsorbed on platinum electrodes

    OpenAIRE

    Feltovich, Susanne D.

    1993-01-01

    The behavior of adsorbed carbon monoxide on platinum was studied using potential difference infrared spectroscopy. Three solvents and three electrolytes were chosen, and data gathered at both high and low adsorbate coverages. The rate of change of IR peak position with applied potential, the Stark tuning rate, was used as an indicator of the local electric field strength at the interface. It was determined that neither solvated cation size nor bulk dielectric constant accoun...

  17. Sequential Electrodeposition of Platinum-Ruthenium at Boron-Doped Diamond Electrodes for Methanol Oxidation

    Directory of Open Access Journals (Sweden)

    Ileana González-González

    2011-01-01

    Full Text Available Sequential electrodeposition of Pt and Ru on boron-doped diamond (BDD films, in 0.5 M H2SO4 by cyclic voltammetry, has been prepared. The potential cycling, in the aqueous solutions of the respective metals, was between 0.00 and 1.00 V versus Ag/AgCl. The catalyst composites, Pt and PtRu, deposited on BDD film substrates, were tested for methanol oxidation. The modified diamond surfaces were also characterized by scanning electron microscopy-X-ray fluorescence-energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and Auger electron spectroscopy. The scanning Auger electron spectroscopy mapping showed the ruthenium signal only in areas where platinum was electrodeposited. Ruthenium does not deposit on the oxidized diamond surface of the boron-doped diamond. Particles with 5–10% of ruthenium with respect to platinum exhibited better performance for methanol oxidation in terms of methanol oxidation peak current and chronoamperometric current stability. The electrogenerated •OH radicals on BDD may interact with Pt surface, participating in the methanol oxidation as shown in oxidation current and the shift in the peak position. The conductive diamond surface is a good candidate as the support for the platinum electrocatalyst, because it ensures catalytic activity, which compares with the used carbon, and higher stability under severe anodic and cathodic conditions.

  18. Nonenzymatic free-cholesterol detection via a modified highly sensitive macroporous gold electrode with platinum nanoparticles.

    Science.gov (United States)

    Lee, Yi-Jae; Park, Jae-Yeong

    2010-12-15

    A sensitive macroporous Au electrode with a highly rough surface obtained through the use of with Pt nanoparticles (macroporous Au-/nPts) is reported. It has been designed for nonenzymatic free-cholesterol biosensor applications. A macroporous Au-/nPts electrode was fabricated by electroplating Pt nanoparticles onto a coral-like shaped macroporous Au electrode structure. The macroporous Au-/nPts electrode was physically characterized by field emission scanning electron microscopy (FESEM). It was confirmed that the Pt nanoparticles were well deposited on the surface of the macroporous Au electrode. The porosity and window pore size of the macroporous Au electrode were 50% and 100-300 nm, respectively. The electroplated Pt nanoparticle size was approximately 10-20 nm. Electrochemical experiments showed that the macroporous Au-/nPts exhibited a much larger surface activation area (roughness factor (RF)=2024.7) than the macroporous Au electrode (RF=46.07). The macroporous Au-/nPts also presented a much stronger electrocatalytic activity towards cholesterol oxidation than does the macroporous Au electrode. At 0.2 V, the electrode responded linearly up to a 5 mM cholesterol concentration in a neutral media, with a detection limit of 0.015 mM and detection sensitivity of 226.2 μA mM(-1) cm(-2). Meanwhile, interfering species such as ascorbic acid (AA), acetaminophen (AP), and uric acid (UA), were effectively avoided. This novel nonenzymatic detection electrode has strong applications as an electrochemically based cholesterol biosensor. Copyright © 2010 Elsevier B.V. All rights reserved.

  19. Tuning of platinum nano-particles by Au usage in their binary alloy for direct ethanol fuel cell: Controlled synthesis, electrode kinetics and mechanistic interpretation

    Science.gov (United States)

    Dutta, Abhijit; Mondal, Achintya; Datta, Jayati

    2015-06-01

    Understanding of the electrode-kinetics and mechanism of ethanol oxidation reaction (EOR) is of considerable interest for optimizing electro-catalysis in direct ethanol fuel cell (DEFC). This work attempts to design Pt based electro-catalyst on carbon support, tuned with gold nano-particles (NPs), for their use in DEFC operating in alkaline medium. The platinum-gold alloyed NPs are synthesized at desired compositions and size (2-10 nm) by controlled borohydride reduction method and successfully characterized by XRD, TEM, EDS and XPS techniques. The kinetic parameters along with the activation energies for the EOR are evaluated over the temperature range 20-80 °C and the oxidation reaction products estimated through ion chromatographic analysis. Compared to single Pt/C catalyst, the over potential of EOR is reduced by ca. 500 mV, at the onset during the reaction, for PtAu/C alloy with only 23% Pt content demonstrating the ability of Au and/or its surface oxides providing oxygen species at much lower potentials compared to Pt. Furthermore, a considerable increase in the peak power density (>191%) is observed in an in-house fabricated direct ethanol anion exchange membrane fuel cell, DE(AEM)FC using the best performing Au covered Pt electrode (23% Pt) compared to the monometallic Pt catalyst.

  20. Synthesis and characterization of platinum thin film as top electrodes for multifunctional layer devices by PLD

    International Nuclear Information System (INIS)

    Coy, L.E.; Ventura, J.; Ferrater, C.; Langenberg, E.; Polo, M.C.; Garcia-Cuenca, M.V.; Varela, M.

    2010-01-01

    Platinum thin films were grown onto (001) oriented SrTiO 3 substrates by means of the pulsed laser deposition technique. Structural and morphological characterizations were performed using XRD and AFM. The influence of substrate temperature and deposition rate was analyzed on the crystallographic properties of the film. As a result, an increment in the crystallinity of the film due to the change on the temperature was observed. On the other hand, Pt films showed a granular morphology and its roughness was related to the fluence and low deposition temperature. Finally their electrical properties were analyzed and discussed as a function of the previous morphological results.

  1. Glucose biosensor based on a platinum electrode modified with rhodium nanoparticles and with glucose oxidase immobilized on gold nanoparticles

    International Nuclear Information System (INIS)

    Guo, Xishan; Jian, Jinming; Liang, Bo; Ye, Xuesong; Zhang, Yelei

    2014-01-01

    We have developed an enzymatic glucose biosensor that is based on a flat platinum electrode which was covered with electrophoretically deposited rhodium (Rh) nanoparticles and then sintered to form a large surface area. The biosensor was obtained by depositing glucose oxidase (GOx), Nafion, and gold nanoparticles (AuNPs) on the Rh electrode. The electrical potential and the fractions of Nafion and GOx were optimized. The resulting biosensor has a very high sensitivity (68.1 μA mM −1 cm −2 ) and good linearity in the range from 0.05 to 15 mM (r = 0.989). The limit of detection is as low as 0.03 mM (at an SNR of 3). The glucose biosensor also is quite selective and is not interfered by electroactive substances including ascorbic acid, uric acid and acetaminophen. The lifespan is up to 90 days. It was applied to the determination of glucose in blood serum, and the results compare very well with those obtained with a clinical analyzer. (author)

  2. Influence of thin film thickness of working electrodes on photovoltaic characteristics of dye-sensitized solar cells

    Directory of Open Access Journals (Sweden)

    Lai Yeong-Lin

    2017-01-01

    Full Text Available This paper presents the study of the influence of thin film thickness of working electrodes on the photovoltaic characteristics of dye-sensitized solar cells. Titanium dioxide (TiO2 thin films, with the thickness from 7.67 to 24.3 μm, were used to fabricate the working electrodes of dye-sensitized solar cells (DSSCs. A TiO2 film was coated on a fluorine-doped tin oxide (FTO conductive glass substrate and then sintered in a high-temperature furnace. On the other hand, platinum (Pt solution was coated onto an FTO substrate for the fabrication of the counter electrode of a DSSC. The working electrode immersed in a dye, the counter electrode, and the electrolyte were assembled to complete a sandwich-structure DSSC. The material analysis of the TiO2 films of DSSCs was carried out by scanning electron microscopy (SEM and ultraviolet-visible (UV-Vis spectroscopy, while the photovoltaic characteristics of DSSCs were measured by an AM-1.5 sunlight simulator. The light transmittance characteristics of the TiO2 working electrode depend on the TiO2 film thickness. The thin film thickness of the working electrode also affects the light absorption of a dye and results in the photovoltaic characteristics of the DSSC, including open-circuited voltage (VOC, short-circuited current density (JSC, fill factor, and photovoltaic conversion efficiency.

  3. Effect of platinum-nanodendrite modification on the glucose-sensing properties of a zinc-oxide-nanorod electrode

    Energy Technology Data Exchange (ETDEWEB)

    Abdul Razak, Khairunisak, E-mail: khairunisak@usm.my [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia); NanoBiotechnology Research & Innovation (NanoBRI), INFORMM, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Neoh, Soo Huan; Ridhuan, N.S.; Mohamad Nor, Noorhashimah [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, 14300 Nibong Tebal, Penang (Malaysia)

    2016-09-01

    Highlights: • Effect of PtNDs on ZnONRs/ITO glucose sensor was studied. • Well-defined PtNDs synthesis using 20 mM K{sub 2}PtCl{sub 4} produced good dispersion between nanodendrites with uniform particle size. • Nafion coating significantly improved the catalytic oxidation of glucose sensor. • Nafion/GO{sub x}/PtNDs/ZnONRs/ITO demonstrated better properties compared with Nafion/GO{sub x}/PtNDs/ITO and Nafion/GO{sub x}/ZnONRs/ITO electrodes. - Abstract: The properties of ZnO nanorods (ZnONRs) decorated with platinum nanodendrites (PtNDs) were studied. Various sizes of PtNDs were synthesized and spin coated onto ZnONRs, which were grown on indium–titanium–oxide (ITO) substrates through a low-temperature hydrothermal method. Scanning electron microscopy and X-ray diffraction analyses were conducted to analyze the morphology and structural properties of the electrodes. The effects of PtND size, glucose concentration, and Nafion amount on glucose-sensing properties were investigated. The glucose-sensing properties of electrodes with immobilized glucose oxidase (GO{sub x}) were measured using cyclic voltammetry. The bio-electrochemical properties of Nafion/GO{sub x}/42 nm PtNDs/ZnONRs/ITO glucose sensor was observed with linear range within 1–18 mM, with a sensitivity value of 5.85 μA/mM and a limit of detection of 1.56 mM. The results of this study indicate that PtNDs/ZnONRs/ITO has potential in glucose sensor applications.

  4. Ordered macroporous platinum electrode and enhanced mass transfer in fuel cells using inverse opal structure.

    Science.gov (United States)

    Kim, Ok-Hee; Cho, Yong-Hun; Kang, Soon Hyung; Park, Hee-Young; Kim, Minhyoung; Lim, Ju Wan; Chung, Dong Young; Lee, Myeong Jae; Choe, Heeman; Sung, Yung-Eun

    2013-01-01

    Three-dimensional, ordered macroporous materials such as inverse opal structures are attractive materials for various applications in electrochemical devices because of the benefits derived from their periodic structures: relatively large surface areas, large voidage, low tortuosity and interconnected macropores. However, a direct application of an inverse opal structure in membrane electrode assemblies has been considered impractical because of the limitations in fabrication routes including an unsuitable substrate. Here we report the demonstration of a single cell that maintains an inverse opal structure entirely within a membrane electrode assembly. Compared with the conventional catalyst slurry, an ink-based assembly, this modified assembly has a robust and integrated configuration of catalyst layers; therefore, the loss of catalyst particles can be minimized. Furthermore, the inverse-opal-structure electrode maintains an effective porosity, an enhanced performance, as well as an improved mass transfer and more effective water management, owing to its morphological advantages.

  5. Systems and methods for producing low work function electrodes

    Science.gov (United States)

    Kippelen, Bernard; Fuentes-Hernandez, Canek; Zhou, Yinhua; Kahn, Antoine; Meyer, Jens; Shim, Jae Won; Marder, Seth R.

    2015-07-07

    According to an exemplary embodiment of the invention, systems and methods are provided for producing low work function electrodes. According to an exemplary embodiment, a method is provided for reducing a work function of an electrode. The method includes applying, to at least a portion of the electrode, a solution comprising a Lewis basic oligomer or polymer; and based at least in part on applying the solution, forming an ultra-thin layer on a surface of the electrode, wherein the ultra-thin layer reduces the work function associated with the electrode by greater than 0.5 eV. According to another exemplary embodiment of the invention, a device is provided. The device includes a semiconductor; at least one electrode disposed adjacent to the semiconductor and configured to transport electrons in or out of the semiconductor.

  6. Nitrogen-Doped Graphene/Platinum Counter Electrodes for Dye-Sensitized Solar Cells

    KAUST Repository

    Lin, Chinan; Lee, Chuanpei; Ho, Shute; Wei, Tzuchiao; Chi, Yuwen; Huang, Kunping; He, Jr-Hau

    2014-01-01

    Nitrogen-doped graphene (NGR) was utilized in dye-sensitized solar cells for energy harvesting. NGR on a Pt-sputtered fluorine-doped tin oxide substrate (NGR/Pt/FTO) as counter electrodes (CEs) achieves the high efficiency of 9.38% via the nitrogen

  7. Nonlocal magnon spin transport in yttrium iron garnet with tantalum and platinum spin injection/detection electrodes

    Science.gov (United States)

    Liu, J.; Cornelissen, L. J.; Shan, J.; van Wees, B. J.; Kuschel, T.

    2018-06-01

    We study the magnon spin transport in the magnetic insulator yttrium iron garnet (YIG) in a nonlocal experiment and compare the magnon spin excitation and detection for the heavy metal paramagnetic electrodes platinum (Pt|YIG|Pt) and tantalum (Ta|YIG|Ta). The electrical injection and detection processes rely on the (inverse) spin Hall effect in the heavy metals and the conversion between the electron spin and magnon spin at the heavy metal|YIG interface. Pt and Ta possess opposite signs of the spin Hall angle. Furthermore, their heterostructures with YIG have different interface properties, i.e. spin mixing conductances. By varying the distance between injector and detector, the magnon spin transport is studied. Using a circuit model based on the diffusion-relaxation transport theory, a similar magnon relaxation length of  ∼10 μm was extracted from both Pt and Ta devices. By changing the injector and detector material from Pt to Ta, the influence of interface properties on the magnon spin transport has been observed. For Ta devices on YIG the spin mixing conductance is reduced compared with Pt devices, which is quantitatively consistent when comparing the dependence of the nonlocal signal on the injector-detector distance with the prediction from the circuit model.

  8. Comparison of lead zirconate titanate thin films on ruthenium oxide and platinum electrodes

    OpenAIRE

    Bursill, Les A.; Reaney, Ian M.; Vijay, Dilip P.; Desu, Seshu B.

    1994-01-01

    High-resolution and bright- and dark-field transmission electron microscopy are used to characterize and compare the interface structures and microstructure of PZT/RuO2/SiO2/Si and PZT/Pt/Ti/SiO2/Si ferroelectric thin films, with a view to understanding the improved fatigue characteristics of PZT thin films with RuO2 electrodes. The RuO2/PZT interface consists of a curved pseudoperiodic minimal surface. The interface is chemically sharp with virtually no intermixing of RuO2 and PZT, as eviden...

  9. Amperometric Biosensor Based on Diamine Oxidase/Platinum Nanoparticles/Graphene/Chitosan Modified Screen-Printed Carbon Electrode for Histamine Detection.

    Science.gov (United States)

    Apetrei, Irina Mirela; Apetrei, Constantin

    2016-03-24

    This work describes the development and optimization studies of a novel biosensor employed in the detection and quantification of histamine in freshwater fish samples. The proposed biosensor is based on a modified carbon screen-printed electrode with diamineoxidase, graphene and platinum nanoparticles, which detects the hydrogen peroxide formed by the chemical process biocatalysed by the enzyme diamine oxidase and immobilized onto the nanostructurated surface of the receptor element. The amperometric measurements with the biosensor have been implemented in buffer solution of pH 7.4, applying an optimal low potential of +0.4 V. The novel biosensor shows high sensitivity (0.0631 μA·μM), low detection limit (2.54 × 10(-8) M) and a broad linear domain from 0.1 to 300 μM. The applicability in natural complex samples and the analytical parameters of this enzyme sensor have been performed in the quantification of histamine in freshwater fish. An excellent correlation among results achieved with the developed biosensor and results found with the standard method for all freshwater fish samples has been achieved.

  10. Proton transfer to charged platinum electrodes. A molecular dynamics trajectory study.

    Science.gov (United States)

    Wilhelm, Florian; Schmickler, Wolfgang; Spohr, Eckhard

    2010-05-05

    A recently developed empirical valence bond (EVB) model for proton transfer on Pt(111) electrodes (Wilhelm et al 2008 J. Phys. Chem. C 112 10814) has been applied in molecular dynamics (MD) simulations of a water film in contact with a charged Pt surface. A total of seven negative surface charge densities σ between -7.5 and -18.9 µC cm(-2) were investigated. For each value of σ, between 30 and 84 initial conditions of a solvated proton within a water slab were sampled, and the trajectories were integrated until discharge of a proton occurred on the charged surfaces. We have calculated the mean rates for discharge and for adsorption of solvated protons within the adsorbed water layer in contact with the metal electrode as a function of surface charge density. For the less negative values of σ we observe a Tafel-like exponential increase of discharge rate with decreasing σ. At the more negative values this exponential increase levels off and the discharge process is apparently transport limited. Mechanistically, the Tafel regime corresponds to a stepwise proton transfer: first, a proton is transferred from the bulk into the contact water layer, which is followed by transfer of a proton to the charged surface and concomitant discharge. At the more negative surface charge densities the proton transfer into the contact water layer and the transfer of another proton to the surface and its discharge occur almost simultaneously.

  11. On the behavior of reduced graphene oxide based electrodes coated with dispersed platinum by alternate current methods in the electrochemical degradation of reactive dyes.

    Science.gov (United States)

    Del Río, A I; García, C; Molina, J; Fernández, J; Bonastre, J; Cases, F

    2017-09-01

    The electrochemical behavior of different carbon-based electrodes with and without nanoparticles of platinum electrochemically dispersed on their surface has been studied. Among others, reduced graphene oxide based electrodes was used to determine the best conditions for the decolorization/degradation of the reactive dye C.I. Reactive Orange 4 in sulfuric medium. Firstly, the electrochemical behavior was evaluated by cyclic voltammetry. Secondly, different electrolyses were performed using two cell configurations: cell with anodic and cathodic compartments separated (divided configuration) and without any separation (undivided configuration). The best results were obtained when reduced graphene oxide based anodes were used. The degree of decolorization was monitored by spectroscopic methods and high performance liquid chromatography. It was found that all of them followed pseudo-first order kinetics. When reduced graphene oxide-based electrodes coated with dispersed platinum by alternate current methods electrodes were used, the lowest energy consumption and the higher decolorization kinetics rate were obtained. Scanning Electronic Microscopy was used to observe the morphological surface differences. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Electrooxidation of borohydride on platinum and gold electrodes: implications for direct borohydride fuel cells

    International Nuclear Information System (INIS)

    Gyenge, Elod

    2004-01-01

    The electrochemical oxidation of BH 4 - in 2 M NaOH on Pt and Au (i.e. catalytic and non-catalytic electrodes, respectively, for BH 4 - hydrolysis accompanied by H 2 evolution) has been studied by cyclic voltammetry, chrono-techniques (i.e., potentiometry, amperometry, coulometry) and electrochemical impedance spectroscopy. In the case of Pt the cyclic voltammetry behaviour of BH 4 - is influenced by both, the catalytic hydrolysis of BH 4 - yielding H 2 (followed by electrooxidation of the latter at peak potentials between -0.7 and -0.9 V versus Ag/AgCl, KCl std ) and direct oxidation of BH 4 - at more positive potentials, i.e., between -0.15 and -0.05 V. Thiourea (TU, 1.5x10 -3 M) was an effective inhibitor of the catalytic hydrolysis associated with BH 4 - electrooxidation on Pt. Therefore, in the presence of TU, only the direct oxidation of BH 4 - has been detected, with peak potentials between -0.2 and 0 V. It is proposed that TU could improve the BH 4 - utilization efficiency and the coulombic efficiency of direct borohydride fuel cells using catalytic anodes. The electrooxidation of BH 4 - on Pt/TU is an overall four-electron process, instead of the maximum eight electrons reported for Au, and it is affected by adsorbed species such as BH 4 - (fractional surface coverage ∼0.3), TU and possibly reaction intermediates

  13. Comparison of lead zirconate titanate thin films on ruthenium oxide and platinum electrodes

    International Nuclear Information System (INIS)

    Bursill, L.A.; Reaney, I.M.

    1994-01-01

    High-resolution and bright- and dark-field transmission electron microscopy are used to characterize and compare the interface structures and microstructure of PZT/RuO 2 /SiO 2 /Si and PZT/Pt/Ti/SiO 2 /Si ferroelectric thin films, with a view to understanding the improved fatigue characteristics of PZT thin films with RuO 2 electrodes. The RuO 2 /PZT interface consists of a curved pseudoperiodic minimal surface. The interface is chemically sharp with virtually no intermixing of RuO 2 and PZT, as evidenced by the atomic resolution images as well as energy dispersive X-ray analysis. A nanocrystalline pyrochlore phase Pb 2 ZrTiO 7-x (x ≠ 1) was found on the top surface of the PZT layer. The PZT/Pt/Ti/SiO 2 /Si thin film was well-crystallized and showed sharp interfaces throughout. Possible reasons for the improved fatigue characteristics of PZT/RuO 2 /SiO 2 /Si thin films are discussed. 13 refs; 7 figs

  14. Comparison of lead zirconate titanate thin films on ruthenium oxide and platinum electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Bursill, L A; Reaney, I M

    1994-12-31

    High-resolution and bright- and dark-field transmission electron microscopy are used to characterize and compare the interface structures and microstructure of PZT/RuO{sub 2}/SiO{sub 2}/Si and PZT/Pt/Ti/SiO{sub 2}/Si ferroelectric thin films, with a view to understanding the improved fatigue characteristics of PZT thin films with RuO{sub 2} electrodes. The RuO{sub 2}/PZT interface consists of a curved pseudoperiodic minimal surface. The interface is chemically sharp with virtually no intermixing of RuO{sub 2} and PZT, as evidenced by the atomic resolution images as well as energy dispersive X-ray analysis. A nanocrystalline pyrochlore phase Pb{sub 2}ZrTiO{sub 7-x} (x {ne} 1) was found on the top surface of the PZT layer. The PZT/Pt/Ti/SiO{sub 2}/Si thin film was well-crystallized and showed sharp interfaces throughout. Possible reasons for the improved fatigue characteristics of PZT/RuO{sub 2}/SiO{sub 2}/Si thin films are discussed. 13 refs; 7 figs.

  15. Nitrogen-Doped Graphene/Platinum Counter Electrodes for Dye-Sensitized Solar Cells

    KAUST Repository

    Lin, Chinan

    2014-12-17

    Nitrogen-doped graphene (NGR) was utilized in dye-sensitized solar cells for energy harvesting. NGR on a Pt-sputtered fluorine-doped tin oxide substrate (NGR/Pt/FTO) as counter electrodes (CEs) achieves the high efficiency of 9.38% via the nitrogen doping into graphene. This is due to (i) the hole-cascading transport at the interface of electrolyte/CEs via controlling the valence band maximum of NGR located between the redox potential of the I-/I- redox couple and the Fermi level of Pt by nitrogen doping, (ii) the extended electron transfer surface effect provided by large-surface-area NGR, (iii) the high charge transfer efficiency due to superior catalytic characteristics of NGR via nitrogen doping, and (iv) the superior light-reflection effect of NGR/Pt/FTO CEs, facilitating the electron transfer from CEs to I3 - ions of the electrolyte and light absorption of dye. The result demonstrated that the NGR/Pt hybrid structure is promising in the catalysis field. (Chemical Presented). © 2014 American Chemical Society.

  16. Electrooxidation of borohydride on platinum and gold electrodes: implications for direct borohydride fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Gyenge, E. [University of British Columbia, Vancouver (Canada). Dept. of Chemical and Biological Engineering

    2004-03-01

    The electrochemical oxidation of BH{sub 4}{sup -} in 2M NaOH on Pt and Au (i.e. catalytic and non-catalytic electrodes, respectively, for BH{sub 4}{sup -} hydrolysis accompanied by H{sub 2} evolution) has been studied by cyclic voltammetry, chrono-techniques (i.e., potentiometry, amperometry, coulometry) and electrochemical impedance spectroscopy. In the case of Pt the cyclic voltammetry behaviour of BH{sub 4}{sup -} is influenced by both, the catalytic hydrolysis of BH{sub 4}{sup -} yielding H{sub 2} followed by electrooxidation of the latter at peak potentials between -0.7 and -0.9 V versus Ag/AgCl, KCl{sub std} and direct oxidation of BH{sub 4}{sup -} at more positive potentials, i.e., between -0.15 and -0.05 V. Thiourea (TU, 1.5 x 10{sup -3} M) was an effective inhibitor of the catalytic hydrolysis associated with BH{sub 4}{sup -} electrooxidation on Pt. Therefore, in the presence of TU, only the direct oxidation of BH{sub 4}{sup -} has been detected, with peak potentials between -0.2 and 0 V. It is proposed that TU could improve the BH{sub 4}{sup -} utilization efficiency and the coulombic efficiency of direct borohydride fuel cells using catalytic anodes. The electrooxidation of BH{sub 4}{sup -} on Pt/TU is an overall four-electron process, instead of the maximum eight electrons reported for Au, and it is affected by adsorbed species such as BH{sub 4}{sup -} (fractional surface coverage {approx}0.3), TU and possibly reaction intermediates. (author)

  17. Low-potential sensitive H2O2 detection based on composite micro tubular Te adsorbed on platinum electrode.

    Science.gov (United States)

    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. Copyright © 2011 Elsevier B.V. All rights reserved.

  18. Electroactive mesoporous yttria stabilized zirconia containing platinum or nickel oxide nanoclusters: a new class of solid oxide fuel cell electrode materials

    Energy Technology Data Exchange (ETDEWEB)

    Mamak, M.; Coombs, N.; Ozin, G.A. [Toronto Univ., ON (Canada). Dept. of Chemistry

    2001-02-01

    The electroactivity of surfactant-templated mesoporous yttria stabilized zirconia, containing nanoclusters of platinum or nickel oxide, is explored by alternating current (AC) complex impedance spectroscopy. The observed oxygen ion and mixed oxygen ion-electron charge-transport behavior for these materials, compared to the sintered-densified non-porous crystalline versions, is ascribed to the unique integration of mesoporosity and nanocrystallinity within the binary and ternary solid solution microstructure. These attributes inspire interest in this new class of materials as candidates for the development of improved performance solid oxide fuel cell electrodes. (orig.)

  19. Study on the Electrochemical Behavior of Iodide at Platinum Electrode in Potassium Chlorate Solution

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Sang Hyuk; Yeon, Jei Won; Song, Kyu Seok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-05-15

    Radioactive iodine-131, is one of the most hazardous fission products which could be released from fuels of nuclear reactors during the severe accident of nuclear power plants. Due to its high radioactivity, high fission yield (2.8%) and hazardous biological effects, the behavior of iodine has been taken interests in many research groups. Iodine is known to be released from the fuels as a cesium iodide form, CsI. And, as nuclear fuels are mostly placed in the water pool, it is easily dissolved in the water after released from the fuels. In water, iodide anion could be oxidized into molecular iodine. As the molecular iodine is a volatile species and the oxidizing rate is affected by many environmental facts such as pH, radiolysis products and temperature, the oxidation reaction of the iodide ion has been considered as an important chemical reaction related to the severe accident of nuclear power plants In present work, the electrochemical behavior of iodide anion was observed by using cyclic voltammetric technique in potassium chlorate solutions. We observed two different oxidation waves in the oxidation potential region. From the comparison with the previous reported results, one is regarded as the oxidation of iodide into molecular iodine. The other is evaluated to be the formation of high-valent iodine-containing compounds

  20. Effect of carbon nano tube working electrode thickness on charge transport kinetics and photo-electrochemical characteristics of dye-sensitized solar cells

    Science.gov (United States)

    Gacemi, Yahia; Cheknane, Ali; Hilal, Hikmat S.

    2018-02-01

    Physiochemical processes at the photo-electrode and the counter electrode of dye sensitized solar cells (DSSCs) involving having carbon nanotubes (CNTs) instead of the TiO2 layer, within the working electrode, are simulated in this work. Attention is paid to find the effect of CNT layer thickness on photo-electrochemical (PEC) characteristics of the CNT-DSSCs. Comparison with other conventional TiO2-DSSC systems, taking into account the working electrode film thickness, is also described here. To achieve these goals, a model is presented to explain charge transport and electron recombination which involve electron photo-excitation in dye molecules, injection of electrons from the excited dye to CNT working electrode conduction band, diffusion of electrons inside the CNT electrode, charge transfer between oxidized dye and (I-) and recombination of electrons. The simulation is based on solving non-linear equations using the Newton-Raphson numerical method. This concept is proposed for modelling numerical Faradaic impedance at the photo-electrode and the platinum counter electrode. It then simulates the cell impedance spectrum describing the locus of the three semicircles in the Nyquist diagram. The transient equivalent circuit model is also presented based on optimizing current-voltage curves of CNT-DSSCs so as to optimize the fill factor (FF) and conversion efficiency (η). The results show that the simulated characteristics of CNT-DSSCs, with different active CNT layer thicknesses, are superior to conventional TiO2-DSSCs.

  1. Platinum/polyaniline transparent counter electrodes for quasi-solid dye-sensitized solar cells with electrospun PVDF-HFP/TiO2 membrane electrolyte

    International Nuclear Information System (INIS)

    Peng, Shengjie; Li, Linlin; Tan, Huiteng; Srinivasan, Madhavi; Mhaisalkar, Subodh G.; Ramakrishna, Seeram; Yan, Qingyu

    2013-01-01

    Composite films of platinum and polyaniline (Pt/PANI) with different Pt loadings are prepared by chemical reduction and then a spin-coating process on fluorine-doped tin oxide (FTO) substrates. The obtained Pt/PANI transparent counter electrodes are applied in quasi-solid dye-sensitized solar cells (QDSCs) from front and rear light illuminations, using electrospun poly(vinylidenefluoride-co-hexafluoropropylene)/TiO 2 (PVDF-HFP/TiO 2 ) as the electrolyte. The analytical results show that the 1.8-nm sized Pt nanoparticles are distributed uniformly in the Pt/PANI film when the Pt loading is 1.5 μg cm −2 . Electrocatalytic activity of the Pt/PANI electrode with 1.5 μg cm −2 Pt loading for the I 3 − /I − redox reaction is higher than the conventional sputtered Pt electrode. Furthermore, the mean optical transmittance of the Pt/PANI electrodes is above 60% in the wavelength of 400–800 nm. The optimal QDSC composed of Pt/PANI with 1.5 μg cm −2 Pt loading exhibits power conversion efficiencies of 6.34% and 3.85%, when measured using an AM1.5G solar simulator at 100 mW cm −2 under front and rear light illuminations. The efficiencies are both higher than those of the QDSCs employing the conventional sputtered Pt counter electrode with 8.3 μg cm −2 Pt loading. Moreover, the QDSC exhibits superior long-term stability. These promising results make the potential application of Pt/PANI films as cost-effective, transparent counter electrodes

  2. Pseudo-indicator behaviour of platinum electrode explored for the potentiometric estimation of non-redox systems.

    Science.gov (United States)

    Raashid, Syed; Chat, Oyais Ahmad; Rizvi, Masood A; Bhat, Mohsin Ahmad; Khan, Badruddin

    2012-11-15

    A pseudo-indicator electrode based potentiometric method for estimation of non-redox metal ions is presented. In the proposed method, nature and concentration specific impact of analyte over the redox potential of ideally polarisable Pt/pregenerated-redox-couple interface forms the basis of quantification. Utility of the method in estimation of six non-redox metal ions viz. Zn(2+), Cu(2+), Ni(2+), Cd(2+), Pb(2+), Al(3+) in the concentration range of 10(-1)-10(-3) moldm(-3), individually and as binary mixtures is also presented. Three types of potentiometric behaviours, which we ascribe to the nature specific thermodynamic and kinetic aspects of metal-EDTA binding, were observed. While Cu(2+), Ni(2+), Pb(2+) and Al(3+) were found to bind EDTA efficiently, without exchanging Fe(3+); Zn(2+) and Cd(2+) were observed to replace Fe(3+) from EDTA. In contrast, Ca(2+) and Mg(2+) were found to show no binding affinity to EDTA in the pH range employed in the present work. The proposed method was also used to explore the reversibility and the Nernestian behaviour of ferricyanide/ferrocyanide redox couple through spectroelectrochemical titration of Zn(2+) with ferrocyanide. The presented method is presaged to be a reliable and low cost future replacement for costly and delicate ion selective electrodes (ISE) in the estimation of non-redox species like Zn(2+), Cu(2+), etc. Copyright © 2012 Elsevier B.V. All rights reserved.

  3. Highly sensitive hydrogen peroxide sensor based on a glassy carbon electrode modified with platinum nanoparticles on carbon nanofiber heterostructures

    International Nuclear Information System (INIS)

    Yang, Yang; Fu, Renzhong; Yuan, Jianjun; Wu, Shiyuan; Zhang, Jialiang; Wang, Haiying

    2015-01-01

    We are presenting a sensor for hydrogen peroxide (H 2 O 2 ) that is based on the use of a heterostructure composed of Pt nanoparticles (NPs) and carbon nanofibers (CNFs). High-density Pt NPs were homogeneously loaded onto a three-dimensional nanostructured CNF matrix and then deposited in a glassy carbon electrode (GCE). The resulting sensor synergizes the advantages of the conducting CNFs and the nanoparticle catalyst. The porous structure of the CNFs also favor the high-density immobilization of the NPs and the diffusion of water-soluble molecules, and thus assists the rapid catalytic oxidation of H 2 O 2 . If operated at a working voltage of −0.2 V (vs. Ag/AgCl), the modified GCE exhibits a linear response to H 2 O 2 in the 5 μM to 15 mM concentration range (total analytical range: 5 μM to 100 mM), with a detection limit of 1.7 μM (at a signal-to-noise ratio of 3). The modified GCE is not interfered by species such as uric acid and glucose. Its good stability, high selectivity and good reproducibility make this electrode a valuable tool for inexpensive amperometric sensing of H 2 O 2 . (author)

  4. Interactions between Human Antibodies and Synthetic Conformational Peptide Epitopes: Innovative Approach for Electrochemical Detection of Biomarkers of Multiple Sclerosis at Platinum Electrodes

    International Nuclear Information System (INIS)

    Bellagha-Chenchah, W.; Sella, C.; Fernandez, F. Real; Peroni, E.; Lolli, F.; Amatore, C.

    2015-01-01

    The detection of human antibodies of Multiple Sclerosis patients was investigated based on the electrochemical oxidation of a synthetic antigenic probe, a glycopeptide Fc-CSF114(Glc) bearing a ferrocenyl moiety. Electrochemical measurements were carried out at platinum microband electrodes without any electrode surface modification. A microfluidic device was designed in order to both minimize peptide consumption and increase the number of experiments with low volumes of samples. The specific interactions between Fc-CSF114(Glc) and antibodies were evidenced through comparison with electrochemical responses obtained from the ferrocenyl unglycosylated peptide Fc-CSF114 used as negative control. The interactions between Fc-CSF114(Glc) and autoantibodies were characterized by a shift of the oxidation potential towards positive values. A mechanism for peptide oxidation was proposed based on a diffusion control of mass transport and the formation of adsorbed layers able to mediate electron transfer. Results showed efficient antigen-antibody recognition without any electrode grafting or further addition of labels in solution. Preliminary tests using human sera from Multiple Sclerosis patients and healthy donors validated this new approach aimed at developing innovative and fast diagnostic tools, based on electrochemical synthetic antigenic probes

  5. Anodic Stripping Voltammetric Detection of Arsenic(III) at Platinum-Iron(III) Nanoparticle Modified Carbon Nanotube on Glassy Carbon Electrode

    International Nuclear Information System (INIS)

    Shin, Seung Hyun; Hong, Hun Gi

    2010-01-01

    The electrochemical detection of As(III) was investigated on a platinum-iron(III) nanoparticles modified multiwalled carbon nanotube on glassy carbon electrode(nanoPt-Fe(III)/MWCNT/GCE) in 0.1 M H 2 SO 4 . The nanoPt-Fe(III)/ MWCNT/GCE was prepared via continuous potential cycling in the range from .0.8 to 0.7 V (vs. Ag/AgCl), in 0.1 M KCl solution containing 0.9 mM K 2 PtCl 6 and 0.6 mM FeCl 3 . The Pt nanoparticles and iron oxide were co-electrodeposited into the MWCNT-Nafion composite film on GCE. The resulting electrode was examined by cyclic voltammetry (CV), scanning electron microscopy (SEM), and anodic stripping voltammetry (ASV). For the detection of As(III), the nanoPt-Fe(III)/MWCNT/GCE showed low detection limit of 10 nM (0.75 ppb) and high sensitivity of 4.76 μAμM -1 , while the World Health Organization's guideline value of arsenic for drinking water is 10 ppb. It is worth to note that the electrode presents no interference from copper ion, which is the most serious interfering species in arsenic detection

  6. Sum frequency generation of CO on (III) and polycrystalline platinum electrode surfaces: Evidence for SFG invisible surface CO

    Energy Technology Data Exchange (ETDEWEB)

    Baldelli, S.; Markovic, N.; Ross, P.; Shen, Y.R.; Somorjai, G.

    1999-10-21

    The vibrational spectroscopy sum frequency generation (SFG) is used to investigate the adsorption of carbon monoxide on the single crystal (111) and polycrystalline platinum surfaces. By varying the frequency and polarization of the light beams, different surface species of CO species are probed. SFG signal intensities for different polarization indicate that adsorbed CO polarizability is significantly perturbed from the gas-phase molecule. The SFG signal of CO disappears well below the main oxidation potential of CO to CO{sub 2}. The disappearance of the CO signal is interpreted as a transformation in the CO layer to a state which is invisible to SFG. The invisible state is suggested to be CO with the bond axis nearly parallel to the platinum surface.

  7. Promotion of the oxidation of carbon monoxide at stepped platinum single-crystal electrodes in alkaline media by lithium and beryllium cations.

    Science.gov (United States)

    Stoffelsma, Chantal; Rodriguez, Paramaconi; Garcia, Gonzalo; Garcia-Araez, Nuria; Strmcnik, Dusan; Marković, Nenad M; Koper, Marc T M

    2010-11-17

    The role of alkali cations (Li(+), Na(+), K(+), Cs(+), and Be(2+)) on the blank voltammetric response and the oxidative stripping of carbon monoxide from stepped Pt single-crystal electrodes in alkaline media has been investigated by cyclic voltammetry. A strong influence of the nature of the cation on both the blank voltammetric profile and the CO oxidation is observed and related to the influence of the cation on the specific adsorption of OH on the platinum surface. Especially Li(+) and Be(2+) cations markedly affect the adsorption of OH and thereby have a significant promoting effect on CO(ads) oxidation. The voltammetric experiments suggest that, on Pt(111), the influence of Li(+) (and Be(2+)) is primarily through a weakening of the repulsive interactions between the OH in the OH adlayer, whereas in the presence of steps also, the onset of OH adsorption is at a lower potential, both on steps and on terraces.

  8. Preparation of Platinum (Pt) Counter Electrode Coated by Electrochemical Technique at High Temperature for Dye-sensitized Solar Cell (DSSC) Application

    Science.gov (United States)

    Ponken, Tanachai; Tagsin, Kamonlapron; Suwannakhun, Chuleerat; Luecha, Jakkrit; Choawunklang, Wijit

    2017-09-01

    Pt counter electrode was coated by electrochemical method. Electrolyte solution was synthesized by platinum (IV) choloride (PtCl4) powder dissolved in hydrochloric acid solution. Pt films were deposited on the FTO substrate. Deposition time of 10, 30 and 60 minutes, the coating current of 5, 10, 15 and 20 mA and electrolyte solution temperatures for Pt layer synthesis of 25, 30 and 40°C were varied. Surface morphology and optical properties was analyzed by digital microscopic and UV-vis spectrophotometer. Pt films exhibit uniform surface area highly for all the conditions of coating current in the deposition time of 30 and 40 minutes at 40°C. Transmittance values of Pt films deposited on FTO substrate has approximately of 5 to 50 % show that occur high reflection corresponding to dye molecule absorption increases. DSSC device was fabricated from the TiO2 standard and immersed in dye N719 for 24 hours. Efficiency was measured by solar simulator. Efficiency value obtains as high as 5.91 % for the coating current, deposition time and solution temperature of 15 mA, 30 minutes and 40°C. Summary, influence of temperature effects efficiency increasing. Pt counter electrode can be prepared easily and the suitable usefully for DSSC.

  9. Collective Behavior of Water on Platinum

    Science.gov (United States)

    Limmer, David; Willard, Adam; Chandler, David

    2012-02-01

    We present the results of molecular dynamics simulations of a interface between water and a platinum electrode. Using importance sampling techniques we probe a variety of collective phenomenon that emerge at the interface. We consider platinum electrodes with two different geometries and discuss how different behaviors result from a competition between geometrical frustration and favorable local interactions.

  10. Corrosion Studies of Platinum Nano-Particles for Fuel Cells

    DEFF Research Database (Denmark)

    Shim, Signe Sarah

    The main focus of the present thesis is on corrosion and prevention of corrosion of platinum particles supported on carbon. This is important for instance in connection with start up and shutdown of fuel cells. The degradation mechanism of platinum particles supported on carbon has been character......The main focus of the present thesis is on corrosion and prevention of corrosion of platinum particles supported on carbon. This is important for instance in connection with start up and shutdown of fuel cells. The degradation mechanism of platinum particles supported on carbon has been...... characterized during oxygen reduction reaction (ORR) condition using identical location (IL) transmission electron microscopy (TEM). A TEM grid was used as the working electrode in an electrochemical setup allowing a direct correlation between the electrochemical response and the TEM analysis. The main results...... thirds and one monolayer of gold on platinum supported on carbon were synthesized by an inverse micelle method. The results obtained appear independent of the gold coverage. It has been shown that the electrochemical active surface areas of the platinum and platinum gold particles synthesized...

  11. Concentration and electrode material dependence of the voltammetric response of iodide on platinum, glassy carbon and boron-doped diamond in the room temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide

    International Nuclear Information System (INIS)

    Bentley, Cameron L.; Bond, Alan M.; Hollenkamp, Anthony F.; Mahon, Peter J.; Zhang, Jie

    2013-01-01

    The electro-oxidation of iodide has been investigated as a function of concentration using steady-state microelectrode voltammetry, transient cyclic voltammetry and linear-sweep semi-integral voltammetry on platinum, glassy carbon and boron-doped diamond electrodes in the room temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide. Two oxidation processes are observed on all of the investigated electrode materials, with the first being assigned to the oxidation of iodide to triiodide (confirmed by UV/visible spectroscopy) and the second being attributed to the oxidation of triiodide to iodine. Iodide oxidation is kinetically more facile on platinum compared to glassy carbon or boron-doped diamond. At elevated bulk iodide concentrations, the nucleation and growth of sparingly soluble electrogenerated iodine at the electrode surface was observed and imaged in situ using optical microscopy. The diffusion coefficient of iodide was determined to be 2.59 (±0.04) × 10 −7 cm 2 s −1 and independent of the bulk concentration of iodide. The steady-state iodide oxidation current measured at a platinum microelectrode was found to be a linear function of iodide concentration, as expected if there are no contributions from non-Stokesian mass-transport processes (electron hopping and/or Grotthuss-type exchange) under the investigated conditions

  12. Comparison of unusual carbon-based working electrodes for electrochemiluminescence sensors.

    Science.gov (United States)

    Noman, Muhammad; Sanginario, Alessandro; Jagadale, Pravin; Demarchi, Danilo; Tagliaferro, Alberto

    2017-06-01

    In this work, unconventional carbon-based materials were investigated for use in electrochemiluminescence (ECL) working electrodes. Precursors such as bamboo, pistachio shells, kevlar ® fibers and camphor were differently treated and used as working electrodes in ECL experiments. After a proper process they were assembled as electrodes and tested in an electrochemical cell. Comparison among them and with a commercial glassy carbon electrode (GCE) shows a very good response for all of them thus demonstrating their potential use as disposable low-cost electrodes for early detection electrochemical analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Electrochemical Characterization of Platinum Nanotubules Made via Template Wetting Nanofabrication

    Directory of Open Access Journals (Sweden)

    Eric Broaddus

    2013-01-01

    Full Text Available Standard oxidation-reduction reactions such as those of ferrocyanide and ferrocene have long been employed in evaluating and comparing new electrode structures with more traditional configurations. A variety of nanostructured carbon electrodes developed in recent years have been reported to exhibit faster electron transfer kinetics than more traditional carbon structures when studied with these redox reactions. This type of comparison has not been widely explored for nanostructured platinum electrodes that have become increasingly common. In this work, a platinum nanotubule array electrode was fabricated via a simple template-based process and evaluated using the standard ferrocyanide redox reaction. The nanotubule array electrodes were observed to more closely approach ideal reversible behavior than a typical Pt black/Nafion fuel cell electrode or a standard polished Pt disc electrode. The apparent heterogeneous electron transfer coefficient was determined using the Nicholson method and found to be one to two orders of magnitude greater for the nanotubule array electrodes, depending on the diameter of the nanotubules, in comparison with these same two more traditional electrode structures.

  14. A survey of reference electrodes for high temperature waters

    International Nuclear Information System (INIS)

    Molander, A.; Eriksson, Sture; Pein, K.

    2000-11-01

    In nuclear power plants, corrosion potential measurements are used to follow the conditions for different corrosion types in reactor systems, particularly IGSCC in BWRs. The goal of this work has been to give a survey of reference electrodes for high temperature water, both those that are used for nuclear environments and those that are judged to possible future development. The reference electrodes that are used today in nuclear power plants for corrosion potential measurements are of three types. Silver chloride electrodes, membrane electrodes and platinum electrodes (hydrogen electrodes). The principals for their function is described as well as the conversion of measured potentials to the SHE scale (Standard Hydrogen Electrode). Silver chloride electrodes consist of an inner reference system of silver chloride in equilibrium with a chloride solution. The silver chloride electrode is the most common reference electrode and can be used in several different systems. Platinum electrodes are usually more robust and are particularly suitable to use in BWR environment to follow the hydrogen dosage, but have limitations at low and no hydrogen dosage. Ceramic membrane electrodes can be with different types of internal reference system. They were originally developed for pH measurements in high temperature water. If pH is constant, the membrane electrode can be used as reference electrode. A survey of ceramic reference electrodes for high temperature water is given. A ceramic membrane of the type used works as an oxygen conductor, so the potential and pH in surrounding medium is in equilibrium with the internal reference system. A survey of the lately development of electrodes is presented in order to explain why the different types of electrodes are developed as well as to give a background to the possibilities and limitations with the different electrodes. Possibilities of future development of electrodes are also given. For measurements at low or no hydrogen dosage

  15. The electrochemical reduction of the purines guanine and adenine at platinum electrodes in several room temperature ionic liquids

    International Nuclear Information System (INIS)

    Zanoni, Maria Valnice Boldrin; Rogers, Emma I.; Hardacre, Christopher; Compton, Richard G.

    2010-01-01

    The reduction of guanine was studied by microelectrode voltammetry in the room temperature ionic liquids (RTILs) N-hexyltriethylammonium bis (trifluoromethanesulfonyl) imide [N 6,2,2,2 ][N(Tf) 2 ], 1-butyl-3-methylimidazolium hexafluorosphosphate [C 4 mim][PF 6 ], N-butyl-N-methyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide [C 4 mpyrr][N(Tf) 2 ], 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide [C 4 mim][N(Tf) 2 ], N-butyl-N-methyl-pyrrolidinium dicyanamide [C 4 mpyrr][N(NC) 2 ] and tris(P-hexyl)-tetradecylphosphonium trifluorotris(pentafluoroethyl)phosphate [P 14,6,6,6 ][FAP] on a platinum microelectrode. In [N 6,2,2,2 ][NTf 2 ] and [P 14,6,6,6 ][FAP], but not in the other ionic liquids studied, guanine reduction involves a one-electron, diffusion-controlled process at very negative potential to produce an unstable radical anion, which is thought to undergo a dimerization reaction, probably after proton abstraction from the cation of the ionic liquid. The rate of this subsequent reaction depends on the nature of the ionic liquid, and it is faster in the ionic liquid [P 14,6,6,6 ][FAP], in which the formation of the resulting dimer can be voltammetrically monitored at less negative potentials than required for the reduction of the parent molecule. Adenine showed similar behaviour to guanine but the pyrimidines thymine and cytosine did not; thymine was not reduced at potentials less negative than required for solvent (RTIL) decomposition while only a poorly defined wave was seen for cytosine. The possibility for proton abstraction from the cation in [N 6,2,2,2 ][NTf 2 ] and [P 14,6,6,6 ][FAP] is noted and this is thought to aid the electrochemical dimerization process. The resulting rapid reaction is thought to shift the reduction potentials for guanine and adenine to lower values than observed in RTILs where the scope for proton abstraction is not present. Such shifts are characteristic of so-called EC processes where reversible electron transfer

  16. Responses of fibroblasts and glial cells to nanostructured platinum surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Pennisi, C P; Sevcencu, C; Yoshida, K [Center for Sensory-Motor Interaction (SMI), Aalborg University, Aalborg (Denmark); Dolatshahi-Pirouz, A; Foss, M; Larsen, A Nylandsted; Besenbacher, F [Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus (Denmark); Hansen, J Lundsgaard [Department of Physics and Astronomy, Aarhus University, Aarhus (Denmark); Zachar, V, E-mail: cpennisi@hst.aau.d [Laboratory for Stem Cell Research, Aalborg University (Denmark)

    2009-09-23

    The chronic performance of implantable neural prostheses is affected by the growth of encapsulation tissue onto the stimulation electrodes. Encapsulation is associated with activation of connective tissue cells at the electrode's metallic contacts, usually made of platinum. Since surface nanotopography can modulate the cellular responses to materials, the aim of the present work was to evaluate the 'in vitro' responses of connective tissue cells to platinum strictly by modulating its surface nanoroughness. Using molecular beam epitaxy combined with sputtering, we produced platinum nanostructured substrates consisting of irregularly distributed nanopyramids and investigated their effect on the proliferation, cytoskeletal organization and cellular morphology of primary fibroblasts and transformed glial cells. Cells were cultured on these substrates and their responses to surface roughness were studied. After one day in culture, the fibroblasts were more elongated and their cytoskeleton less mature when cultured on rough substrates. This effect increased as the roughness of the surface increased and was associated with reduced cell proliferation throughout the observation period (4 days). Morphological changes also occurred in glial cells, but they were triggered by a different roughness scale and did not affect cellular proliferation. In conclusion, surface nanotopography modulates the responses of fibroblasts and glial cells to platinum, which may be an important factor in optimizing the tissue response to implanted neural electrodes.

  17. Electron transfer processes occurring on platinum neural stimulating electrodes: pulsing experiments for cathodic-first, charge-balanced, biphasic pulses for 0.566  ⩽  k  ⩽  2.3 in rat subcutaneous tissues

    Science.gov (United States)

    Kumsa, Doe W.; Bhadra, Narendra; Hudak, Eric M.; Mortimer, J. Thomas

    2017-10-01

    Objective. Our mission is twofold: (1) find a way to safely inject more charge through platinum electrodes than the Shannon limit (k  =  1.75) permits and (2) nurture an interest in the neural stimulation community to understand the electron transfer process occurring on neural stimulating electrodes. Approach. We report here on measurements of the electrode potential, performed on platinum neural stimulating electrodes in the subcutaneous space of an anesthetized rat under neural stimulation conditions. Main results. The results for six platinum electrodes with areas ranging from 0.2 mm2 to 12.7 mm2 were similar to prior results in sulfuric acid, except that the measured potentials were shifted negative 0.36 V because of the pH difference between the two media. The anodic ‘end’ potential, measured at t  =  20 ms after the onset of the biphasic current pulse, was the primary focus of the data collected because previous results had shown that as charge injection crosses the Shannon limit (k  =  1.75), this potential moves into a range where platinum surface oxidation and dissolution is likely to occur. The behavior of V e(t  =  20 ms) over a range of electrode surface areas studied was consistent with our sulfuric acid study. Implicit, but little noticed, in Shannon’s formulation is that small and large platinum electrodes behave the same in terms of k value; our data supports this idea. Significance. We hypothesize that the k  =  1.75 Shannon limit for safe stimulation designates a charge-injection boundary above which platinum toxicity becomes a relevant consideration for living cells around an electrode, a possibility that can be directly tested, and is a vital step forward in mission (1).

  18. Dissolution of Platinum in Hydrochloric Acid Under Industrial-Scale Alternating Current Polarization

    Science.gov (United States)

    Myrzabekov, B. E.; Bayeshov, A. B.; Makhanbetov, A. B.; Mishra, B.; Baigenzhenov, O. S.

    2018-02-01

    The electrochemical behavior of platinum in a hydrochloric acid solution under polarization by an industrial-scale alternating current has been investigated. For the electrical dissolution of platinum, titanium is used as an auxiliary electrode, which increases the yield of platinum dissolution by 12.5 pct. The influence of the concentration of hydrochloric acid, the current densities of the platinum and titanium electrodes, and the temperature of the electrolyte on the efficiency of the process of dissolving platinum have all been studied.

  19. Online monitoring of electrocatalytic reactions of alcohols at platinum and gold electrodes in acidic, neutral and alkaline media by capillary electrophoresis with contactless conductivity detection (EC-CE-C4 D).

    Science.gov (United States)

    Ferreira Santos, Mauro Sérgio; Silva Lopes, Fernando; Gutz, Ivano Gebhardt Rolf

    2017-11-01

    An EC-CE-C 4 D flow system was applied to the investigation of electrocatalytic processes by monitoring carboxylic acids formed during the electro-oxidation at various potentials of primary alcohols (mixture of 1 mmol/L of ethanol, n-propanol, n-butanol and n-pentanol) in acidic, neutral and alkaline media. The electro-oxidation was carried out on gold and platinum disk electrodes (3 mm of diameter) in a thin-layer electrochemical flow cell. Products were sampled 50 μm apart from the electrode directly into the capillary. All the generated carboxylates were determined in near real time (less than 2 min) by CE-C 4 D in counter-flow mode, with Tris/HCl buffer solution (pH 8.6) as BGE. Long sequences of 5-min experiments were run automatically, exploring the applied potential, electrolysis time and solution composition. Electro-oxidation at 1.5 V (versus Ag/AgCl quasi-reference) during 50 s in acidic medium was found appropriate for both Pt and Au electrodes when the determination of alcohols after derivatization is intended. A noteworthy selectivity effect was observed on the Au electrode. The signal corresponding to pentanoate is similar on both electrodes while the signal of ethanoate (acetate) is four times larger on gold than on platinum. The carboxylate signals were lower in alkaline medium (below the determination limit on Pt) than in acidic and neutral media. On gold, the formation of carboxylates was anticipated (0.85 V in alkaline medium versus 1.40 V in neutral medium). The automatic online monitoring of electrochemical processes by EC-CE-C 4 D holds great potential to investigate ionic/ionizable intermediates/products of new electrocatalysts and/or alternative fuels. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Work ethics of employees in the platinum mine industry / A.S. Phale

    OpenAIRE

    Phale, Antoinette Sephiwe

    2003-01-01

    There are different factors that contribute to the development of work ethics. One such factor is the individual in relation to the work, the organisation and the environment. Work ethics are believed to be related to performance, productivity and the disciplining of extreme misconduct. Work ethics are also associated with economic success. It is recommended that the organisation should find out more about work ethics and how work ethics could be to the advantage of the organis...

  1. Fabrication of a three-electrode battery using hydrogen-storage materials

    Science.gov (United States)

    Roh, Chi-Woo; Seo, Jung-Yong; Moon, Hyung-Seok; Park, Hyun-Young; Nam, Na-Yun; Cho, Sung Min; Yoo, Pil J.; Chung, Chan-Hwa

    2015-04-01

    In this study, an energy storage device using a three-electrode battery is fabricated. The charging process takes place during electrolysis of the alkaline electrolyte where hydrogen is stored at the palladium bifunctional electrode. Upon discharging, power is generated by operating the alkaline fuel cell using hydrogen which is accumulated in the palladium hydride bifunctional electrode during the charging process. The bifunctional palladium electrode is prepared by electrodeposition using a hydrogen bubble template followed by a galvanic displacement reaction of platinum in order to functionalize the electrode to work not only as a hydrogen storage material but also as an anode in a fuel cell. This bifunctional electrode has a sufficiently high surface area and the platinum catalyst populates at the surface of electrode to operate the fuel cell. The charging and discharging performance of the three-electrode battery are characterized. In addition, the cycle stability is investigated.

  2. Working electrodes from amalgam paste for electrochemical measurements

    Czech Academy of Sciences Publication Activity Database

    Josypčuk, Bohdan; Šestáková, Ivana

    2008-01-01

    Roč. 20, č. 4 (2008), s. 426-433 ISSN 1040-0397 R&D Projects: GA ČR GA203/07/1195; GA ČR GA521/06/0496 Institutional research plan: CEZ:AV0Z40400503 Keywords : voltammetry * paste amalgam * silver amalgam * paste electrode Subject RIV: CG - Electrochemistry Impact factor: 2.901, year: 2008

  3. In-situ thermoelectrochemistry working with heated electrodes

    CERN Document Server

    Gründler, Peter

    2015-01-01

    This book represents the first rigorous treatment of thermoelectrochemistry, providing an overview that will stimulate electrochemists to develop and apply modern thermoelectrochemical methods. While classical static approaches are also covered, the emphasis lies on methods that make it possible to independently vary temperature such as in-situ heating of electrodes by means of electric current, microwaves or lasers. For the first time, "hot-wire electrochemistry" is examined in detail. The theoretical background presented addresses all aspects of temperature impacts in the context of electroc

  4. A survey of reference electrodes for high temperature waters; Oeversikt av referenselektroder i hoegtemperaturvatten

    Energy Technology Data Exchange (ETDEWEB)

    Molander, A.; Eriksson, Sture; Pein, K. [Studsvik Nuclear, Nykoeping (Sweden)

    2000-11-01

    In nuclear power plants, corrosion potential measurements are used to follow the conditions for different corrosion types in reactor systems, particularly IGSCC in BWRs. The goal of this work has been to give a survey of reference electrodes for high temperature water, both those that are used for nuclear environments and those that are judged to possible future development. The reference electrodes that are used today in nuclear power plants for corrosion potential measurements are of three types. Silver chloride electrodes, membrane electrodes and platinum electrodes (hydrogen electrodes). The principals for their function is described as well as the conversion of measured potentials to the SHE scale (Standard Hydrogen Electrode). Silver chloride electrodes consist of an inner reference system of silver chloride in equilibrium with a chloride solution. The silver chloride electrode is the most common reference electrode and can be used in several different systems. Platinum electrodes are usually more robust and are particularly suitable to use in BWR environment to follow the hydrogen dosage, but have limitations at low and no hydrogen dosage. Ceramic membrane electrodes can be with different types of internal reference system. They were originally developed for pH measurements in high temperature water. If pH is constant, the membrane electrode can be used as reference electrode. A survey of ceramic reference electrodes for high temperature water is given. A ceramic membrane of the type used works as an oxygen conductor, so the potential and pH in surrounding medium is in equilibrium with the internal reference system. A survey of the lately development of electrodes is presented in order to explain why the different types of electrodes are developed as well as to give a background to the possibilities and limitations with the different electrodes. Possibilities of future development of electrodes are also given. For measurements at low or no hydrogen dosage

  5. Erosion on spark plug electrodes; Funkenerosion an Zuendkerzenelektroden

    Energy Technology Data Exchange (ETDEWEB)

    Rager, J.

    2006-07-01

    Durability of spark plugs is mainly determined by spark gap widening, caused by electrode wear. Knowledge about the erosion mechanisms of spark plug materials is of fundamental interest for the development of materials with a high resistance against electrode erosion. It is therefore crucial to identify those parameters which significantly influence the erosion behaviour of a material. In this work, a reliable and reproducible testing method is presented which produces and characterizes electrode wear under well-defined conditions and which is capable of altering parameters specifically. Endurance tests were carried out to study the dependence of the wear behaviour of pure nickel and platinum on the electrode temperature, gas, electrode gap, electrode diameter, atmospheric pressure, and partial pressure of oxygen. It was shown that erosion under nitrogen is negligible, irrespective of the material. This disproves all common mechanism discussed in the literature explaining material loss of spark plug electrodes. Based on this observation and the variation of the mentioned parameters a new erosion model was deduced. This relies on an oxidation of the electrode material and describes the erosion of nickel and platinum separately. For nickel, electrode wear is caused by the removal of an oxide layer by the spark. In the case of platinum, material loss occurs due to the plasma-assisted formation and subsequent evaporation of volatile oxides in the cathode spot. On the basis of this mechanism a new composite material was developed whose erosion resistance is superior to pure platinum. Oxidation resistant metal oxide particles were added to a platinum matrix, thus leading to a higher erosion resistance of the composite. However, this can be decreased by a side reaction, the separation of oxygen from the metal oxides, which effectively assists the oxidation of the matrix. This reaction can be suppressed by using highly stable oxides, characterized by a large negative Gibbs

  6. Oxygen Transfer on Substituted ZrO2, Bi2O3, and CeO2 Electrolytes with Platinum Electrodes II. A-C Impedance Study

    NARCIS (Netherlands)

    Verkerk, M.J.; Burggraaf, A.J.

    1983-01-01

    An equivalent electrical circuit that describes the electrode processes on different electrolytes, using porous Pt electrodes,is given. Diffusional processes are important and have to be presented by Warburg components in the circuit. Theoverall electrode process is rate limited by diffusion of

  7. Schiff Base modified on CPE electrode and PCB gold electrode for selective determination of silver ion

    Science.gov (United States)

    Leepheng, Piyawan; Suramitr, Songwut; Phromyothin, Darinee

    2017-09-01

    The schiff base was synthesized by 2,5-thiophenedicarboxaldehyde and 1,2,4-thiadiazole-3,5-diamine with condensation method. There was modified on carbon paste electrode (CPE) and Printed circuit board (PCB) gold electrode for determination silver ion. The schiff base modified electrodes was characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM), respectively. The electrochemical study was reported by cyclic voltammetry method and impedance spectroscopy using modified electrode as working electrode, platinum wire and Ag/AgCl as counter electrode and reference electrode, respectively. The modified electrodes have suitable detection for Ag+. The determination of silver ions using the modified electrodes depended linearly on Ag+ concentration in the range 1×10-10 M to 1×10-7 M, with cyclic voltammetry sensitivity were 2.51×108 μAM-1 and 1.88×108 μAM-1 for PCB gold electrode and CPE electrode, respectively, limits of detection were 5.33×10-9 M and 1.99×10-8 M for PCB gold electrode and CPE electrode, respectively. The modified electrodes have high accuracy, inexpensive and can applied to detection Ag+ in real samples.

  8. Poly(3,3-dibenzyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine/Platinum Composite Films as Potential Counter Electrodes for Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Jung-Chuan Chou

    2017-07-01

    Full Text Available In this study, poly(3,3-dibenzyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepine/platinum composite films (PProDOT-Bz2/Pt were used as counter electrodes (CEs in dye-sensitized solar cells (DSSCs. The composite films were prepared on fluorine-doped tin oxide (FTO glass by radio frequency (RF sputtering to deposit platinum (Pt for 30 s. Afterwards, PProDOT-Bz2 was deposited on the Pt–FTO glass via electrochemical polymerization. The electron transfer process of DSSCs was investigated using electrochemical impedance spectroscopy (EIS and cyclic voltammetry (CV. The DSSCs with 0.05 C/cm2 PProDOT-Bz2-Pt composite films showed an open circuit voltage (Voc of 0.70 V, a short-circuit current density (Jsc of 7.27 mA/cm2, and a fill factor (F.F. of 68.74%. This corresponded to a photovoltaic conversion efficiency (η of 3.50% under a light intensity of 100 mW/cm2.

  9. Phosphoric acid fuel cell platinum use study

    Science.gov (United States)

    Lundblad, H. L.

    1983-05-01

    The U.S. Department of Energy is promoting the private development of phosphoric acid fuel cell (PAFC) power plants for terrestrial applications. Current PAFC technology utilizes platinum as catalysts in the power electrodes. The possible repercussions that the platinum demand of PAFC power plant commercialization will have on the worldwide supply and price of platinum from the outset of commercialization to the year 2000 are investigated. The platinum demand of PAFC commercialization is estimated by developing forecasts of platinum use per unit of generating capacity and penetration of PAFC power plants into the electric generation market. The ability of the platinum supply market to meet future demands is gauged by assessing the size of platinum reserves and the capability of platinum producers to extract, refine and market sufficient quantities of these reserves. The size and timing of platinum price shifts induced by the added demand of PAFC commercialization are investigated by several analytical methods. Estimates of these price shifts are then used to calculate the subsequent effects on PAFC power plant capital costs.

  10. Importance of Electrode Hot-Pressing Conditions for the Catalyst Performance of Proton Exchange Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Andersen, Shuang Ma; Dhiman, Rajnish; Larsen, Mikkel Juul

    2015-01-01

    The catalyst performance in a proton exchange membrane fuel cell (PEMFC) depends on not only the choice of materials, but also on the electrode structure and in particular on the interface between the components. In this work, we demonstrate that the hot-pressing conditions used during electrode...... lamination have a great influence on the catalyst properties of a low-temperature PEMFC, especially on its durability. Lamination pressure, temperature and duration were systematically studied in relation to the electrochemical surface area, platinum dissolution, platinum particle size and electrode surface...

  11. Voltammetric determination of the endocrine disruptor diethylstilbestrol by using a glassy carbon electrode modified with a composite consisting of platinum nanoparticles and multiwalled carbon nanotubes

    International Nuclear Information System (INIS)

    Hu, Xiaobin; Zhang, Rongfei

    2016-01-01

    A nanocomposite consisting of multi-walled carbon nanotubes (MWCNTs) decorated with Pt nanoparticles (Pt-NPs) was synthesized via an ionic liquid-assisted method. The composite was characterized by transmission electron microscopy, X-ray diffraction patterns, and X-ray photo-electron spectroscopy. The results showed the Pt-NPs to be evenly deposited on the surface of the MWCNTs, with diameters ranging from about 2 nm to 3 nm. The nanocomposite was used to modify a glassy carbon electrode which then revealed a substantial catalytic activity for the oxidation of diethylstilbestrol (DES), best at a working potential of 0.73 V (vs. Ag/AgCl) at pH 7. The electrochemical oxidation mechanism is discussed. The peak current in square wave voltammetry is linearly related to the concentration of DES in the 0.1 to 25 μM range. The limit of detection (at an SNR of 3) is 12 nM. (author)

  12. Electrochemical deposition of molybdenum sulfide thin films on conductive plastic substrates as platinum-free flexible counter electrodes for dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Chao-Kuang; Hsieh, Chien-Kuo, E-mail: jack_hsieh@mail.mcut.edu.tw

    2015-06-01

    In this study, pulsed electrochemical deposition (pulsed ECD) was used to deposit molybdenum sulfide (MoS{sub x}) thin films on indium tin oxide/polyethylene naphthalate (ITO/PEN) substrates as flexible counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). The surface morphologies and elemental distributions of the prepared MoS{sub x} thin films were examined using field-emission scanning electron microscope (FE-SEM) equipped with energy-dispersive X-ray spectroscopy. The chemical states and crystallinities of the prepared MoS{sub x} thin films were examined by X-ray photoelectron spectroscopy and X-ray diffraction, respectively. The optical transmission (T (%)) properties of the prepared MoS{sub x} samples were determined by ultraviolet–visible spectrophotometry. Cyclic voltammetry (CV) and Tafel-polarization measurements were performed to analyze the electrochemical properties and catalytic activities of the thin films for redox reactions. The FE-SEM results showed that the MoS{sub x} thin films were deposited uniformly on the ITO/PEN flexible substrates via the pulsed ECD method. The CV and Tafel-polarization curve measurements demonstrated that the deposited MoS{sub x} thin films exhibited excellent performances for the reduction of triiodide ions. The photoelectric conversion efficiency (PCE) of the DSSC produced with the pulsed ECD MoS{sub x} thin-film CE was examined by a solar simulator. In combination with a dye-sensitized TiO{sub 2} working electrode and an iodine-based electrolyte, the DSSC with the MoS{sub x} flexible CE showed a PCE of 4.39% under an illumination of AM 1.5 (100 mW cm{sup −2}). Thus, we report that the MoS{sub x} thin films are active catalysts for triiodide reduction. The MoS{sub x} thin films are prepared at room temperature and atmospheric pressure and in a simple and rapid manner. This is an important practical contribution to the production of flexible low-cost thin-film CEs based on plastic substrates. The MoS{sub x

  13. High work function transparent middle electrode for organic tandem solar cells

    NARCIS (Netherlands)

    Moet, D. J. D.; de Bruyn, P.; Blom, P. W. M.

    2010-01-01

    The use of poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) in combination with ZnO as middle electrode in solution-processed organic tandem solar cells requires a pH modification of the PEDOT:PSS dispersion. We demonstrate that this neutralization leads to a reduced work function

  14. The use of a hierarchically platinum-free electrode composed of tin oxide decorated polypyrrole on nanoporous copper in catalysis of methanol electrooxidation

    Energy Technology Data Exchange (ETDEWEB)

    Asghari, Elnaz, E-mail: elnazasghari@yahoo.com; Ashassi-Sorkhabi, Habib; Vahed, Akram; Rezaei-Moghadam, Babak; Charmi, Gholam Reza

    2016-01-01

    Tin oxide nanoparticles were synthesized through a galvanostatic pathway on polypyrrole, PPy, coated nanoporous copper. The morphology and surface analysis of the assemblies were evaluated by field emission scanning electron microscopy, FESEM, and energy dispersive X-ray, EDX, analysis, respectively. The electrocatalytic behavior of electrodes was studied by cyclic voltammetry and chronoamperometry tests in methanol solution. FESEM results showed that uniformly distributed nanoparticles with diameters of about 20–30 nm have been dispersed on PPy matrix. Cyclic voltammetry and chronoamperometry tests in methanol solution showed a significant enhancement in the catalytic action of PPy after decoration of tin oxide nanoparticles. Porous Cu/PPy/SnO{sub x} electrodes showed enhanced anodic peak current density for methanol oxidation compared to smooth Cu/PPy/SnO{sub x} and porous Cu/PPy. The effects of synthesis current density and time on the electrocatalytic behavior of the electrodes were evaluated. The significant enhancement of electrocatalytic behavior of the Cu/PPy electrode after decoration of SnO{sub x} overlayer was attributed to the effect of tin oxide on the adsorption of intermediates of methanol oxidation as well as oxidation of bi-products such as CO; huge tendency of tin oxides for dehydrogenation of the alcohols and the increase in microscopic surface area of the electrodes were introduced as other affecting factors. - Highlights: • Nanoporous copper–zinc substrates were formed by chemical leaching of zinc. • Polypyrrole thin film was electrodeposited on nanoporous copper. • Thin oxide nanoparticles were synthesized electrochemically on polypyrrole layer. • The catalytic performance of the electrodes was evaluated for methanol oxidation.

  15. Bacterial and fungal killing by iontophoresis with long-lived electrodes.

    OpenAIRE

    Davis, C P; Wagle, N; Anderson, M D; Warren, M M

    1991-01-01

    Iontophoresis with gold, carbon, and platinum electrodes was shown to effectively reduce or eliminate gram-positive, gram-negative, and Candida albicans inocula in synthetic urine. Platinum and gold electrodes were more effective than carbon electrodes, but platinum showed the best longevity and may reduce or eliminate microbial colonization of catheters.

  16. Optically Transparent Thin-Film Electrode Chip for Spectroelectrochemical Sensing

    Energy Technology Data Exchange (ETDEWEB)

    Branch, Shirmir D.; Lines, Amanda M.; Lynch, John A.; Bello, Job M.; Heineman, William R.; Bryan, Samuel A.

    2017-07-03

    The electrochemical and spectroelectrochemical applications of an optically transparent thin film electrode chip are investigated. The working electrode is composed of indium tin oxide (ITO); the counter and quasi-reference electrodes are composed of platinum. The stability of the platinum quasi-reference electrode is modified by coating it with a planar, solid state Ag/AgCl layer. The Ag/AgCl reference is characterized with scanning electron microscopy and energy-dispersive X-ray spectroscopy. Open circuit potential measurements indicate that the potential of the planar Ag/AgCl electrode varies a maximum of 20 mV over four days. Cyclic voltammetry measurements show that the electrode chip is comparable to a standard electrochemical cell. Randles-Sevcik analysis of 10 mM K3[Fe(CN)6] in 0.1 M KCl using the electrode chip shows a diffusion coefficient of 1.59 × 10-6 cm2/s, in comparison to the standard electrochemical cell value of 2.38 × 10-6 cm2/s. By using the electrode chip in an optically transparent thin layer electrode (OTTLE), the spectroelectrochemical modulation of [Ru(bpy)3]2+ florescence was demonstrated, achieving a detection limit of 36 nM.

  17. Low-cost carbon-based counter electrodes for dye sensitized solar cells

    International Nuclear Information System (INIS)

    Barberio, M; Imbrogno, A; Bonanno, A; Xu, F; Grosso, D R

    2015-01-01

    In this work, we present the realization of four carbon-based counter electrodes for dye-sensitized solar cells. The photovoltaic behaviours of counter electrodes realized with graphene, multiwalled carbon nanotubes, and nanocomposites of multiwalled carbon nanotubes and metal nanoparticles are compared with those of classical electrodes (amorphous carbon and platinum). Our results show an increase of about 50% in PCE for graphene and Ag/carbon nanotube electrodes with respect to amorphous carbon and of 25% in comparison to platinum. An improvement in cell stability is also observed; in fact, the PCE of all carbon-based cells assumes a constant value during a period of one month while that with the Pt electrode decreases by 50% in one week. (paper)

  18. Sample preparation and electrochemical data of Co3O4 working electrode for seawater splitting

    Directory of Open Access Journals (Sweden)

    Malkeshkumar Patel

    2017-10-01

    Full Text Available In this data article, we presented the electrochemical data of the working electrode made of Co3O4 semi-transparent film. Electrochemically stable, porous nature of Kirkendall-diffusion grown Co3O4 films were applied to generate hydrogen from the seawater splitting (Patel et al., 2017 [1]. The data presented in this article includes the photograph of prepared samples, polarization curves for water oxidation and Tafel plot, linear sweep voltammetry measurements under the pulsed light condition in 0.1 M Na2S2O3 electrolyte, and transient photoresponses with natural sea water. Moreover, seawater splitting using the Co3O4 working electrode is demonstrated.

  19. Determination of work function of graphene under a metal electrode and its role in contact resistance.

    Science.gov (United States)

    Song, Seung Min; Park, Jong Kyung; Sul, One Jae; Cho, Byung Jin

    2012-08-08

    Although the work function of graphene under a given metal electrode is critical information for the realization of high-performance graphene-based electronic devices, relatively little relevant research has been carried out to date. In this work, the work function values of graphene under various metals are accurately measured for the first time through a detailed analysis of the capacitance-voltage (C-V) characteristics of a metal-graphene-oxide-semiconductor (MGOS) capacitor structure. In contrast to the high work function of exposed graphene of 4.89-5.16 eV, the work function of graphene under a metal electrode varies depending on the metal species. With a Cr/Au or Ni contact, the work function of graphene is pinned to that of the contacted metal, whereas with a Pd or Au contact the work function assumes a value of ∼4.62 eV regardless of the work function of the contact metal. A study of the gate voltage dependence on the contact resistance shows that the latter case provides lower contact resistance.

  20. Platinum catalyst formed on carbon nanotube by the in-liquid plasma method for fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Show, Yoshiyuki; Hirai, Akira; Almowarai, Anas; Ueno, Yutaro

    2015-12-01

    In-liquid plasma was generated in the carbon nanotube (CNT) dispersion fluid using platinum electrodes. The generated plasma spattered the surface of the platinum electrodes and dispersed platinum particles into the CNT dispersion. Therefore, the platinum nanoparticles were successfully formed on the CNT surface in the dispersion. The platinum nanoparticles were applied to the proton exchange membrane fuel cell (PEMFC) as a catalyst. The electrical power of 108 mW/cm{sup 2} was observed from the fuel cell which was assembled with the platinum catalyst formed on the CNT by the in-liquid plasma method. - Highlights: • The platinum catalyst was successfully formed on the CNT surface in the dispersion by the in-liquid plasma method. • The electrical power of 108 mW/cm{sup 2} was observed from the fuel cell which was assembled with the platinum catalyst formed on the CNT by the in-liquid plasma method.

  1. Characterization of electrochemically modified polycrystalline platinum surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Krebs, L.C.; Ishida, Takanobu.

    1991-12-01

    The characterization of electrochemically modified polycrystalline platinum surfaces has been accomplished through the use of four major electrochemical techniques. These were chronoamperometry, chronopotentiommetry, cyclic voltammetry, and linear sweep voltammetry. A systematic study on the under-potential deposition of several transition metals has been performed. The most interesting of these were: Ag, Cu, Cd, and Pb. It was determined, by subjecting the platinum electrode surface to a single potential scan between {minus}0.24 and +1.25 V{sub SCE} while stirring the solution, that the electrocatalytic activity would be regenerated. As a consequence of this study, a much simpler method for producing ultra high purity water from acidic permanganate has been developed. This method results in water that surpasses the water produced by pyrocatalytic distillation. It has also been seen that the wettability of polycrystalline platinum surfaces is greatly dependent on the quantity of oxide present. Oxide-free platinum is hydrophobic and gives a contact angle in the range of 55 to 62 degrees. We have also modified polycrystalline platinum surface with the electrically conducting polymer poly-{rho}-phenylene. This polymer is very stable in dilute sulfuric acid solutions, even under applied oxidative potentials. It is also highly resistant to electrochemical hydrogenation. The wettability of the polymer modified platinum surface is severely dependent on the choice of supporting electrolyte chosen for the electrochemical polymerization. Tetraethylammonium tetrafluoroborate produces a film that is as hydrophobic as Teflon, whereas tetraethylammonium perchlorate produces a film that is more hydrophilic than oxide-free platinum.

  2. Characterization of electrochemically modified polycrystalline platinum surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Krebs, Leonard C. [State Univ. of New York (SUNY), Stony Brook, NY (United States); Ishida, Takanobu [State Univ. of New York (SUNY), Stony Brook, NY (United States)

    1991-12-01

    The characterization of electrochemically modified polycrystalline platinum surfaces has been accomplished through the use of four major electrochemical techniques. These were chronoamperometry, chronopotentiommetry, cyclic voltammetry, and linear sweep voltammetry. A systematic study on the under-potential deposition of several transition metals has been performed. The most interesting of these were: Ag, Cu, Cd, and Pb. It was determined, by subjecting the platinum electrode surface to a single potential scan between -0.24 and +1.25 VSCE while stirring the solution, that the electrocatalytic activity would be regenerated. As a consequence of this study, a much simpler method for producing ultra high purity water from acidic permanganate has been developed. This method results in water that surpasses the water produced by pyrocatalytic distillation. It has also been seen that the wettability of polycrystalline platinum surfaces is greatly dependent on the quantity of oxide present. Oxide-free platinum is hydrophobic and gives a contact angle in the range of 55 to 62 degrees. We have also modified polycrystalline platinum surface with the electrically conducting polymer poly-ρ-phenylene. This polymer is very stable in dilute sulfuric acid solutions, even under applied oxidative potentials. It is also highly resistant to electrochemical hydrogenation. The wettability of the polymer modified platinum surface is severely dependent on the choice of supporting electrolyte chosen for the electrochemical polymerization. Tetraethylammonium tetrafluoroborate produces a film that is as hydrophobic as Teflon, whereas tetraethylammonium perchlorate produces a film that is more hydrophilic than oxide-free platinum.

  3. A Change to the Platinum Publications | Poster

    Science.gov (United States)

    Please be advised that the Poster will no longer publish the “Platinum Publications” series listing recent NCI at Frederick publications. All published research represents a valuable addition to the fight against cancer, AIDS, and infectious diseases—thus, the “Platinum Publications” did not adequately commend all of the important work done by NCI at Frederick researchers.

  4. Direct chronopotentiometric analysis of riboflavin using a glassy carbon vessel as the working electrode

    Directory of Open Access Journals (Sweden)

    Brezo Tanja Ž.

    2016-01-01

    Full Text Available A new method for the determination of riboflavin (vitamin B2 was developed based on chronopotentiometry with a glassy carbon process vessel macroelectrode. The method optimisation included investigation of the most important experimental parameters: type and concentration of the supporting electrolyte, initial potential, reduction current, and the working electrode surface area. The reduction signal of riboflavin appeared at about -0.12 V vs. Ag/AgCl (3.5 mol/dm3 KCl electrode in 0.025 mol/dm3 HCl as the supporting electrolyte. A linear response was obtained in the the range of 0.05-4 mg/dm3. The limit of detection and limit of quantitation were 0.018 mg/dm3 and 0.054 mg/dm3, respectively. Due to the use of specific working electrode, a significant enhancement of the method relative sensitivity of about 10 times was achieved. The accuracy of the defined method was confirmed by HPLC analyses. The developed method was successfully applied for the quantitation of riboflavin in various pharmaceutical multivitamin preparations. [Projekat Ministarstva nauke Republike Srbije, br. III 46009

  5. Platinum-induced structural collapse in layered oxide polycrystalline films

    International Nuclear Information System (INIS)

    Wang, Jianlin; Liu, Changhui; Huang, Haoliang; Fu, Zhengping; Peng, Ranran; Zhai, Xiaofang; Lu, Yalin

    2015-01-01

    Effect of a platinum bottom electrode on the SrBi 5 Fe 1−x Co x Ti 4 O 18 layered oxide polycrystalline films was systematically studied. The doped cobalt ions react with the platinum to form a secondary phase of PtCoO 2 , which has a typical Delafossite structure with a weak antiferromagnetism and an exceptionally high in-plane electrical conductivity. Formation of PtCoO 2 at the interface partially consumes the cobalt dopant and leads to the structural collapsing from 5 to 4 layers, which was confirmed by X-ray diffraction and high resolution transmission electron microscopy measurements. Considering the weak magnetic contribution from PtCoO 2 , the observed ferromagnetism should be intrinsic of the Aurivillius compounds. Ferroelectric properties were also indicated by the piezoresponse force microscopy. In this work, the platinum induced secondary phase at the interface was observed, which has a strong impact on Aurivillius structural configuration and thus the ferromagnetic and ferroelectric properties

  6. Characterization of Deposited Platinum Contacts onto Discrete Graphene Flakes for Electrical Devices

    KAUST Repository

    Holguin Lerma, Jorge Alberto

    2016-01-01

    The electrical measurements confirm a 99.5% reduction in contact resistance after vacuum thermal annealing at 300 °C. Parallel to this, Raman characterization confirms the formation of a nanocrystalline carbon structure over the electrode. While this could suggest an enhancement of the electrical transport in the device, an additional thermal annealing step in air at 300 °C, promoted the oxidation and removal of the carbon shell and confirmed that the contact resistance remained the same. Overall this shows that the carbon shell along the electrode has no significant role in the contact resistance. Finally, the challenges based on topographical analysis of the deposited electrodes are discussed. Reduction of the electrode’s height down to one-third of the initial value, increased surface roughness, formation of voids along the electrodes and the onset of platinum nanoparticles near the area of deposition, represent a challenge for future work.

  7. Iodometric determination of platinum(4) using amperometry

    International Nuclear Information System (INIS)

    Zakharov, V.A.; Gavva, N.F.; Songina, O.A.

    1976-01-01

    The possibility of iodometric determination of platinum (4) by amperometric titration has been investigated. Titration has been conducted at zero potential of platinum reference electrode. Voltampere curves and absorption spectra of the solutions have been recorded to elucidate the nature of platinum (4) interaction with iodide-ion. It has been established that in the case of small excess of iodide complex [PtI 6 ] 2- is formed. When there is a considerable excess of KI, platinum (4) is reduced to Pt(2) with the formation of [PtI 4 ] 2 - and liberation of free iodine. Optimal for iodometric titration of Pt(4) is the use of acetate ot phosphate background solution with pH 6-8 with respect to 1M KI which is attained by adding 3 g of solid KI to 20 ml of the solution being titrated. Under these conditions the limit of platinum detection is 0.5 mkg/ml. Determination of Pt (4) is not hindered by the presence of 200-fold amounts of Cr(6), V(5), and Ni(2) as well as by 20-10-fold amounts of As(5), Sb(5), Se(4), Te(4), Rh(3), and Ir(3), Determination is hindered by the presence of Pd(2), Fe(3), Ir(4), and Cu(2) which, however, can easily be overcome. The possibility has been shown of using the developed technique for analysis of platinum catalysts and alloys

  8. Biosensors Based on Urease Adsorbed on Nickel, Platinum, and Gold Conductometric Transducers Modified with Silicalite and Nanozeolites

    Science.gov (United States)

    Kucherenko, Ivan S.; Soldatkin, Oleksandr O.; Kasap, Berna Ozansoy; Kurç, Burcu Akata; Melnyk, Volodymir G.; Semenycheva, Lyudmila M.; Dzyadevych, Sergei V.; Soldatkin, Alexei P.

    This work describes urease-based conductometric biosensors that were created using nontypical method of urease immobilization via adsorption on micro- and nanoporous particles: silicalite and nanocrystalline zeolites Beta (BEA) and L. Conductometric transducers with nickel, gold, and platinum interdigitated electrodes were used. Active regions of the nickel transducers were modified with microparticles using two procedures—spin coating and drop coating. Gold and platinum transducers were modified with silicalite using drop coating since it was more effective. Scanning electron microscopy was used to evaluate effectiveness of these procedures. The procedure of spin coating produced more uniform layers of particles (and biosensors had good reproducibility of preparation), but it was more complicated, drop coating was easier and led to formation of a bulk of particles; thus, biosensors had bigger sensitivity but worse reproducibility of preparation. Urease was immobilized onto transducers modified with particles by physical adsorption. Analytical characteristics of the obtained biosensors for determination of urea (calibration curves, sensitivity, limit of detection, linear concentration range, noise of responses, reproducibility of signal during a day, and operational stability during 3 days) were compared. Biosensors with all three particles deposited by spin coating showed similar characteristics; however, silicalite was a bit more effective. Biosensors based on nickel transducers modified by drop coating had better characteristics in comparison with modification by spin coating (except reproducibility of preparation). Transducers with gold electrodes showed best characteristics while creating biosensors, platinum electrodes were slightly inferior to them, and nickel electrodes were the worst.

  9. Temperature dependence of the work function of ruthenium-based gate electrodes

    International Nuclear Information System (INIS)

    Alshareef, H.N.; Wen, H.C.; Luan, H.F.; Choi, K.; Harris, H.R.; Senzaki, Y.; Majhi, P.; Lee, B.H.; Foran, B.; Lian, G.

    2006-01-01

    The effect of device fabrication temperature on the work function of ruthenium (Ru) metal gate and its bilayers was investigated. The work function shows strong temperature dependence when Ru electrodes are deposited on silicon oxide, SiO 2 , but not on hafnium silicates (HfSiO x ). Specifically, the work function of Ru on SiO 2 increased from 4.5 eV at 500 deg. C to 5.0 eV at 700 deg. C. On further annealing to 900 deg. C or higher, the work function dropped to about 4.4 eV. In the case of HfSiO x , the work function of Ru changed by less than 100 mV over the same temperature range. Identical temperature dependence was observed using hafnium (Hf)/Ru and tantalum (Ta)/Ru bilayers. However, the peak values of the work function decreased with increasing Hf/Ru and Ta/Ru thickness ratios. Materials analysis suggests that these trends are driven by interactions at the Ru metal gate-dielectric interface

  10. Wearable Solid-State Supercapacitors Operating at High Working Voltage with a Flexible Nanocomposite Electrode.

    Science.gov (United States)

    Li, Xiaoyan; Wang, Jun; Zhao, Yaping; Ge, Fengyan; Komarneni, Sridhar; Cai, Zaisheng

    2016-10-05

    The proposed approach for fabricating ultralight self-sustained electrodes facilitates the structural integration of highly flexible carbon nanofibers, amino-modified multiwalled carbon nanotubes (AM-MWNT), and MnO 2 nanoflakes for potential use in wearable supercapacitors. Because of the higher orientation of AM-MWNT and the sublimation of terephthalic acid (PTA) in the carbonization process, freestanding electrodes could be realized with high porosity and flexibility and could possess remarkable electrochemical properties without using polymer substrates. Wearable symmetric solid-state supercapacitors were further assembled using a LiCl/PVA gel electrolyte, which exhibit a maximum energy density of 44.57 Wh/kg (at a power density of 337.1 W/kg) and a power density of 13330 W/kg (at an energy density of 19.64 Wh/kg) with a working voltage as high as 1.8 V. Due to the combination of several favorable traits such as flexibility, high energy density, and excellent electrochemical cyclability, the presently developed wearable supercapacitors with wide potential windows are expected to be useful for new kinds of portable electric devices.

  11. Noise analysis of gate electrode work function engineered recessed channel (GEWE-RC) MOSFET

    International Nuclear Information System (INIS)

    Agarwala, Ajita; Chaujar, Rishu

    2012-01-01

    This paper discusses the noise assessment, using ATLAS device simulation software, of a gate electrode work function engineered recessed channel (GEWE-RC) MOSFET involving an RC and GEWE design integrated onto a conventional MOSFET. Furthermore, the behaviour of GEWE-RC MOSFET is compared with that of a conventional MOSFET having the same device parameters. This paper thus optimizes and predicts the feasibility of a novel design, i.e., GEWE-RC MOSFET for high-performance applications where device and noise reduction is a major concern. The noise metrics taken into consideration are: minimum noise figure and optimum source impedance. The statistical tools auto correlation and cross correlation are also analysed owing to the random nature of noise.

  12. One-step electrochemically-codeposited polyaniline-platinum for dye-sensitized solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Thiangkaew, Anongnad; Keothongkham, Khamsone; Maiaugree, Wasan; Jarernboon, Wirat [Khon Kaen University, Khon Kaen (Thailand); Kamwanna, Teerasak; Pimanpang, Samuk; Amornkitbamrung, Vittaya [Khon Kaen University, Khon Kaen (Thailand); Nanotec-KKU Center of Excellence on Advanced Nanomaterials for Energy Production and Storage, Khon Kaen (Thailand)

    2014-05-15

    Platinum, polyaniline and composite polyaniline-platinum films were coated on conductive glass by using electrochemical deposition. They were then used as dye-sensitized solar cell counter electrodes. The efficiencies of platinum, polyaniline and composite polyaniline-platinum cells were 2.47, 4.47 and 6.62%, respectively. The improvement of composite polyaniline-platinum solar cell efficiency over pure polyaniline and platinum cells is because of an increase in the film's catalytic activity and a decrease in charge-transfer resistance between its counter electrode and electrolyte, as observed by using cyclic voltammogram and electrochemical impedance spectroscopy measurements, respectively. Co-deposition of polyaniline and Pt catalysts was confirmed by the presence of Pt and N peaks in the X-ray photoelectron spectroscopy spectrum.

  13. Electrochemical reduction of oxygen on small platinum particles supported on carbon in concentrated phosphoric acid. 2. Effects of teflon content in the catalyst layer and baking temperature of the electrode

    Energy Technology Data Exchange (ETDEWEB)

    Maoka, T.

    1988-03-01

    A relation between hydrophobicity (or wettability) of a porous gas diffusion electrode for use in a phosphoric acid fuel cell and its cathode performance (activity toward electrochemical oxygen reduction) was examined. The hydrophobicity of the gas diffusion electrode was regulated by changing either the amount of Teflon (PTFE) content in the catalyst layer or baking temperature of the electrode. The Tafel slope or electrochemical oxygen reduction became twice as high as that of the ordinary electrode when the wettability of electrode toward phosphoric acid was high. This fact supports a flooded agglomerate model as the mode of this type of porous gas diffusion electrode.

  14. Rhenium–platinum antitumor systems

    Directory of Open Access Journals (Sweden)

    A. V. Shtemenko

    2017-04-01

    Full Text Available This review provides an overlook of design (in short, antitumor and other biological activity of quadruple-bonded cluster dirhenium(III compounds and their synergism with cisplatin. In particular, we describe the work of the rhenium-platinum antitumor system (introduction of rhenium and platinum compounds. Among known metal-based anticancer drugs and drug candidates dirhenium(III compounds differ profoundly due to their strong antiradical and antioxidant properties determined by quadruple bond unsaturation. Such advantages of metal complexes as more expressed redox chemical propertie should be exploited for creating more efficient anticancer drugs. Combination of drugs leads to synergistic effects and/or to lowe­ring toxicity of platinides and is very promising in cancer chemotherapy. The review covers the follo­wing items: design of quadruple bonded dirhenium(III clusters, their spectral and antiradical properties (in short; interaction of the dirhenium(III compounds with lipids and formation of liposomes; interaction of the dirhenium(III compounds with erythrocytes and their antihemolytic activity in the models of hemolytic anemia; anticancer activity of dirhenium clusters and work of the rhenium-platinum antitumor system; antianemic and antioxidant properties of the dirhenium(III compounds in the model of tumor growth; interaction of the dirhenium(III compounds with nucleobases and DNA. Some modern trends in the field of bioinorganic and medicinal chemi­stry are also considered regarding their connection to the rhenium-platinum system efficiency: use of combinational therapy and nanomaterials; involvement of some biologically active ligands and redox-activation strategy, etc.

  15. Sheath-flow electrochemical detection of amino acids with a copper wire electrode in capillary electrophoresis.

    Science.gov (United States)

    Inoue, Junji; Kaneta, Takashi; Imasaka, Totaro

    2012-09-01

    Here, we report the detection of native amino acids using a sheath-flow electrochemical detector with a working electrode made of copper wire. A separation capillary that was inserted into a platinum tube in the detector acted as a grounded electrode for electrophoresis and as a flow channel for sheath liquid. Sheath liquid flowed outside the capillary to support the transport of the separated analytes to the working electrode for electrochemical detection. The copper wire electrode was aligned at the outlet of the capillary in a wall-jet configuration. Amino acids injected into the capillary were separated following elution from the end of the capillary and detection by the copper electrode. Three kinds of copper electrodes with different diameters-50, 125, and 300 μm-were examined to investigate the effect of the electrode diameter on sensitivity. The peak widths of the analytes were independent of the diameter of the working electrode, while the 300-μm electrode led to a decrease in the signal-to-noise ratio compared with the 50- and 125-μm electrodes, which showed no significant difference. The flow rate of the sheath liquid was also varied to optimize the detection conditions. The limits of detection for amino acids ranged from 4.4 to 27 μM under optimal conditions. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Preparation of platinum-free tubular dye-sensitized solar cells by electrophoretic deposition

    Directory of Open Access Journals (Sweden)

    Khwanchit Wongcharee

    2016-10-01

    Full Text Available Tubular dye-sensitized solar cells (DSSCs were developed by replacing expensive materials with lower cost materials as follows: (1 replacing conductive glass electrodes with titanium (Ti wires and (2 replacing platinum (Pt catalyst with the mixture of multi-walled carbon nanotubes, MWCNTs and Poly(3,4-ethylenedioxythiophene-poly(styrenesulfonate, PEDOT-PSS. Platinized counter electrodes were used as the standard counter electrodes for comparison. The effects of the chemical treatment of titanium wire substrate and electrophoretic deposition condition on the efficiency of DSSCs were also investigated. The chemical treatment of titanium wires was carried out by soaking the wires in HF-HNO3 solutions at three different concentrations of 0.8, 1.6 and 2.4 M and three different soaking durations of 5, 10 and 15 min. The optimum condition was found at HF-HNO3 concentration of 0.8 M and soaking duration of 10 min. Film coating on working electrodes was performed using electrophoretic technique at three different voltages of 5, 8 and 10 V and four different coating durations of 1, 3, 5 and 7 min. Then, the optimum condition at deposition voltage of 5 V and deposition duration of 5 min was applied for film deposition on counter electrodes. The efficiency of DSSC with CNTs/TiO2 counter electrode was 0.03%. The addition of PEDOT-PSS improved the efficiency of DSSC to 0.08%.

  17. The different electron transport of two nanotubes incorporated in working electrode of dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiaobo, E-mail: zhangxiaobo@chnu.edu.cn [School of Physics, Huaibei Normal University, Huaibei 235000, Anhui (China); Eco-Materials and Renewable Energy Research Centre (ERERC), Nanjing University, Nanjing 210093 (China); Tian, Hanmin; Wang, Xiangyan; Xue, Guogang; Tian, Zhipeng; Zhang, Jiyuan; Yuan, Shikui [Eco-Materials and Renewable Energy Research Centre (ERERC), Nanjing University, Nanjing 210093 (China); Yu, Tao; Zou, Zhigang [Eco-Materials and Renewable Energy Research Centre (ERERC), Nanjing University, Nanjing 210093 (China); National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093 (China)

    2013-11-25

    Highlights: •Two TiO{sub 2} nanotubes are separately incorporated in working electrode of DSSCs. •The 6-μm-tubes incorporation improves electron transport in the cell. •The 1-μm-tubes incorporation impedes electron transport in the cell. •Both 1-D electron diffusion and nanotube percolation promote electron transport. •Electron residing at the end of 1-μm-tubes maybe impedes electron transport. -- Abstract: Two different-length (6 μm and 1 μm) TiO{sub 2} nanotubes were prepared and incorporated in working electrode of dye-sensitized solar cells (DSSCs). The analyses of the electrochemical impedance spectra of cells demonstrate that, the electron transport resistance R{sub w} decreases and increases separately to 0.3 Ω in 6-μm-tubes-cell and to 15.1 Ω in 1-μm-tubes-cell comparing with that 1.4 Ω in P25-cell, reflecting the improved electron transport in 6-μm-tubes-cell and impeded electron transport in 1-μm-tubes-cell. The reason is ascribed to the different electron transport in working electrode due to the incorporation of nanotubes. For the 6-μm-tubes incorporation, both 1-D electron diffusion along nanotubes and nanotube percolation improve electron transport in working electrode, but they cannot improve electron transport for the 1-μm-tubes incorporation. On the contrary, the 1-μm-tubes incorporation may impede electron transport because of electron residing occurring seriously at the end of 1-μm-tubes. The results of this work will help to understand the specific nature of electron transport in TiO{sub 2} nanotubes in DSSCs.

  18. Electrochemical DNA biosensors based on platinum nanoparticles combined carbon nanotubes

    International Nuclear Information System (INIS)

    Zhu Ningning; Chang Zhu; He Pingang; Fang Yuzhi

    2005-01-01

    Platinum nanoparticles were used in combination with multi-walled carbon nanotubes (MWCNTs) for fabricating sensitivity-enhanced electrochemical DNA biosensor. Multi-walled carbon nanotubes and platinum nanoparticles were dispersed in Nafion, which were used to fabricate the modification of the glassy carbon electrode (GCE) surface. Oligonucleotides with amino groups at the 5' end were covalently linked onto carboxylic groups of MWCNTs on the electrode. The hybridization events were monitored by differential pulse voltammetry (DPV) measurement of the intercalated daunomycin. Due to the ability of carbon nanotubes to promote electron-transfer reactions, the high catalytic activities of platinum nanoparticles for chemical reactions, the sensitivity of presented electrochemical DNA biosensors was remarkably improved. The detection limit of the method for target DNA was 1.0 x 10 -11 mol l -1

  19. Surface modification of recording electrodes

    Directory of Open Access Journals (Sweden)

    Iaci Miranda Pereira

    2013-01-01

    Full Text Available Waterborne Polyurethanes (PUs are a family of polymers that contains urethane linkages synthesized in an aqueous environment and are thus free of organic solvents. Recently, waterborne PUs have been extensively studied for biomedical applications because of their biocompatibility. The present work investigates the following: (1 the impact on electrical performance of electrode materials (platinum and silicon modified chemically by a layer of waterborne PU, and (2 the behavior of rat cardiac fibroblasts and rat cardiomyocytes when in contact with an electrode surface. Diisocyanate and poly(caprolactone diol were the main reagents for producing PUs. The electrochemical impedance of the electrode/electrolyte interface was accessed by electrochemical impedance spectroscopy. The cellular viability, proliferation, and morphology changes were investigated using an MTT assay. Cardiomyocyte adherence was observed by scanning electron microscopy. The obtained surface was uniform, flat, and transparent. The film showed good adhesion, and no peeling was detected. The electrochemical impedance decreased over time and was influenced by the ionic permeability of the PU layer. The five samples did not show cytotoxicity when in contact with neonatal rat cells.

  20. AAO-CNTs electrode on microfluidic flow injection system for rapid iodide sensing.

    Science.gov (United States)

    Phokharatkul, Ditsayut; Karuwan, Chanpen; Lomas, Tanom; Nacapricha, Duangjai; Wisitsoraat, Anurat; Tuantranont, Adisorn

    2011-06-15

    In this work, carbon nanotubes (CNTs) nanoarrays in anodized aluminum oxide (AAO-CNTs) nanopore is integrated on a microfluidic flow injection system for in-channel electrochemical detection of iodide. The device was fabricated from PDMS (polydimethylsiloxane) microchannel bonded on glass substrates that contains three-electrode electrochemical system, including AAO-CNTs as a working electrode, silver as a reference electrode and platinum as an auxiliary electrode. Aluminum, stainless steel catalyst, silver and platinum layers were sputtered on the glass substrate through shadow masks. Aluminum layer was then anodized by two-step anodization process to form nanopore template. CNTs were then grown in AAO template by thermal chemical vapor deposition. The amperometric detection of iodide was performed in 500-μm-wide and 100-μm-deep microchannels on the microfluidic chip. The influences of flow rate, injection volume and detection potential on the current response were optimized. From experimental results, AAO-CNTs electrode on chip offers higher sensitivity and wider dynamic range than CNTs electrode with no AAO template. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. Integration of Microchip Electrophoresis with Electrochemical Detection Using an Epoxy-Based Molding Method to Embed Multiple Electrode Materials

    Science.gov (United States)

    Johnson, Alicia S.; Selimovic, Asmira; Martin, R. Scott

    2012-01-01

    This paper describes the use of epoxy-encapsulated electrodes to integrate microchip-based electrophoresis with electrochemical detection. Devices with various electrode combinations can easily be developed. This includes a palladium decoupler with a downstream working electrode material of either gold, mercury/gold, platinum, glassy carbon, or a carbon fiber bundle. Additional device components such as the platinum wires for the electrophoresis separation and the counter electrode for detection can also be integrated into the epoxy base. The effect of the decoupler configuration was studied in terms of the separation performance, detector noise, and the ability to analyze samples of a high ionic strength. The ability of both glassy carbon and carbon fiber bundle electrodes to analyze a complex mixture was demonstrated. It was also shown that a PDMS-based valving microchip can be used along with the epoxy embedded electrodes to integrate microdialysis sampling with microchip electrophoresis and electrochemical detection, with the microdialysis tubing also being embedded in the epoxy substrate. This approach enables one to vary the detection electrode material as desired in a manner where the electrodes can be polished and modified in a similar fashion to electrochemical flow cells used in liquid chromatography. PMID:22038707

  2. Characterization of Deposited Platinum Contacts onto Discrete Graphene Flakes for Electrical Devices

    KAUST Repository

    Holguin Lerma, Jorge A.

    2016-05-03

    For years, electron beam induced deposition has been used to fabricate electrical contacts for micro and nanostructures. The role of the contact resistance is key to achieve high performance and efficiency in electrical devices. The present thesis reports on the electrical, structural and chemical characterization of electron beam deposited platinum electrodes that are exposed to different steps of thermal annealing and how they are used in four-probe devices of ultrathin graphite (uG) flakes (<100nm thickness). The device integration of liquid phase exfoliated uG is demonstrated, and its performance compared to devices made with analogous mechanically exfoliated uG. For both devices, similar contact resistances of ~2kΩ were obtained. The electrical measurements confirm a 99.5% reduction in contact resistance after vacuum thermal annealing at 300 °C. Parallel to this, Raman characterization confirms the formation of a nanocrystalline carbon structure over the electrode. While this could suggest an enhancement of the electrical transport in the device, an additional thermal annealing step in air at 300 °C, promoted the oxidation and removal of the carbon shell and confirmed that the contact resistance remained the same. Overall this shows that the carbon shell along the electrode has no significant role in the contact resistance. Finally, the challenges based on topographical analysis of the deposited electrodes are discussed. Reduction of the electrode’s height down to one-third of the initial value, increased surface roughness, formation of voids along the electrodes and the onset of platinum nanoparticles near the area of deposition, represent a challenge for future work.

  3. The effects of electron and hole transport layer with the electrode work function on perovskite solar cells

    Science.gov (United States)

    Deng, Quanrong; Li, Yiqi; Chen, Lian; Wang, Shenggao; Wang, Geming; Sheng, Yonglong; Shao, Guosheng

    2016-09-01

    The effects of electron and hole transport layer with the electrode work function on perovskite solar cells with the interface defects were simulated by using analysis of microelectronic and photonic structures-one-dimensional (AMPS-1D) software. The simulation results suggest that TiO2 electron transport layer provides best device performance with conversion efficiency of 25.9% compared with ZnO and CdS. The threshold value of back electrode work function for Spiro-OMeTAD, NiO, CuI and Cu2O hole transport layer are calculated to be 4.9, 4.8, 4.7 and 4.9 eV, respectively, to reach the highest conversion efficiency. The mechanisms of device physics with various electron and hole transport materials are discussed in details. The device performance deteriorates gradually as the increased density of interface defects located at ETM/absorber or absorber/HTM. This research results can provide helpful guidance for materials and metal electrode choice for perovskite solar cells.

  4. Ethanol oxidation on a nichrome-supported spherical platinum microparticle electrocatalyst prepared by electrodeposition

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhen-Hui; Li, Jing; Dong, Xiaoya; Wang, Dong; Chen, Tiwei; Qiao, Haiyan; Huang, Aiping [College of Chemistry and Environmental Science, Henan Key Laboratory for Environmental Pollution Control, Henan Normal University, Jianshe Road, Xinxiang 453007 (China)

    2008-11-15

    A novel electrode was rapidly prepared by depositing microparticle platinum onto a nichrome substrate in dilute chloroplatinic acid solution by cyclic voltammetry. The SEM results revealed that the deposits were composed of spherical Pt microparticles. Cyclic voltammetry and chronoamperometry were used for the characterization of the electrodes. Results of the electrochemical measurements showed that the spherical Pt microparticle electrodes retained the properties of metal platinum, increased the catalytic activity and promoted the electrocatalytic oxidation of ethanol. Moreover, the deposited Pt microparticles improved the electrochemical properties of the support material and reduced the dosage of noble metal platinum remarkably. The cost could be reduced dramatically by decreasing the contents of platinum. The spherical Pt microparticles deposited on the nichrome supports are likely a potential electrocatalyst for ethanol electrooxidation. (author)

  5. ELECTROCHEMICAL DETERMINATION OF ETHANOL, 2- PROPANOL AND 1-BUTANOL ON GLASSY CARBON ELECTRODE MODIFIED WITH NICKEL OXIDE FILM

    Directory of Open Access Journals (Sweden)

    A. Benchettara

    2014-12-01

    Full Text Available In this work, we present the modification of a glassy carbon electrode with nickel oxide film which is performed in two successive steps. In the first one, the electrochemical deposition of metallic nickel on the glassy carbon electrode (GCE is achieved in 0.1M boric acid; in the second step, the metallic deposit is anodically oxidized in 0.1M NaOH. These two operations were carried out in a three electrode cell with a filiform platinum auxiliary electrode, a SCE as potential reference and a working microelectrode of modified glassy carbon with nickel oxides. This electrode is characterized by several electrochemical techniques and is used for the catalytic determination of ethanol, 2-propanol and 1-butanol in 0.1 M NaOH. The proposed chemical mechanism shows that NiO2 acts as a mediator.

  6. ELECTROCHEMICAL DETERMINATION OF ETHANOL, 2- PROPANOL AND 1-BUTANOL ON GLASSY CARBON ELECTRODE MODIFIED WITH NICKEL OXIDE FILM

    Directory of Open Access Journals (Sweden)

    A. Benchettara

    2015-07-01

    Full Text Available In this work, we present the modification of a glassy carbon electrode with nickel oxide film which is performed in two successive steps. In the first one, the electrochemical deposition of metallic nickel on the glassy carbon electrode (GCE is achieved in 0.1M boric acid; in the second step, the metallic deposit is anodically oxidized in 0.1M NaOH. These two operations were carried out in a three electrode cell with a filiform platinum auxiliary electrode, a SCE as potential reference and a working microelectrode of modified glassy carbon with nickel oxides. This electrode is characterized by several electrochemical techniques and is used for the catalytic determination of ethanol, 2-propanol and 1-butanol in 0.1 M NaOH. The proposed chemical mechanism shows that NiO2 acts as a mediator.

  7. High Electrocatalytic Response of a Mechanically Enhanced NbC Nanocomposite Electrode Towards Hydrogen Evolution Reaction

    KAUST Repository

    Coy, Emerson; Yate, Luis; Valencia, Drochss P; Aperador, Willian; Siuzdak, Katarzyna; Torruella, Pau; Azanza, Eduardo; Estrade, Sonia; Iatsunskyi, Igor; Peiró , Francesca; Zhang, Xixiang; Tejada, Javier; Ziolo, Ronald F.

    2017-01-01

    Resistant and efficient electrocatalysts for hydrogen evolution reaction (HER) are desired to replace scarce and commercially expensive platinum electrodes. Thin film electrodes of metal-carbides are a promising alternative due to their reduced

  8. Nanometer-spaced electrodes with calibrated separation

    NARCIS (Netherlands)

    Kervennic, Y.V.; Van der Zant, H.S.J.; Morpurgo, A.F.; Gurevich, L.; Kouwenhoven, L.P.

    2002-01-01

    We have fabricated pairs of platinum electrodes with separation between 20 and 3.5 nm. Our technique combines electron beam lithography and chemical electrodeposition. We show that the measurement of the conductance between the two electrodes through the electrolyte provides an accurate and

  9. Platinum uptake from chloride solutions using biosorbents

    Directory of Open Access Journals (Sweden)

    Mehmet Hakan Morcali

    2013-04-01

    Full Text Available Present work investigates platinum uptake from synthetically prepared, dilute platinum-bearing solutions using biomass residues, i.e. pistachio nut shell and rice husk, which are abundant in Turkey, and provides a comparison between these two biosorbents. Effects of the different uptake parameters, sorbent dosage, contact time, temperature and pH of solution on platinum uptake (% were studied in detail on a batch sorption. Before the pistachio nut shell was activated, platinum uptake (% was poor compared to the rice husk. However, after the pistachio nut shell was activated at 1000 °C under an argon atmosphere, the platinum uptake (% increased two-fold. The pistachio nut shell (original and activated and rice husk were shown to be better than commercially available activated carbon in terms of adsorption capacity. These two sorbents have also been characterized by FTIR and SEM. Adsorption equilibrium data best complied with the Langmuir isotherm model. Maximum adsorption capacities, Qmax, at 25 °C were found to be 38.31 and 42.02 mg.g- 1for the activated pistachio nut shell and rice husk, respectively. Thermodynamic calculations using the measured ∆H°, ∆S° and ∆G° values indicate that the uptake process was spontaneous and endothermic. The experimental data were shown to be fit the pseudo-second-order kinetic model.

  10. Investigation of the electrochemical behaviour of thermally prepared Pt-IrO2 electrodes

    Directory of Open Access Journals (Sweden)

    Konan Honoré Kondro

    2008-04-01

    Full Text Available Different IrO2 electrodes in which the molar percentage of platinum (Pt varies from 0 %mol Pt to 100 %mol Pt were prepared on titanium (Ti substrate by thermal decomposition techniques. The electrodes were characterized physically (SEM, XPS and electrochemically and then applied to methanol oxidation. The SEM micrographs indicated that the electrodes present different morphologies depending on the amount of platinum in the deposit and the cracks observed on the 0 %mol Pt electrode diminish in size tending to a compact and rough surface for 70 %mol Pt electrode. XPS results indicate good quality of the coating layer deposited on the titanium substrate. The voltammetric investigations in the supporting electrolyte indicate that the electrodes with low amount of platinum (less than 10 %mol Pt behave as pure IrO2. But in the case of electrodes containing more than 40 %mol Pt, the voltammograms are like that of platinum. Electrocatalytic activity towards methanol oxidation was observed with the electrodes containing high amount of platinum. Its oxidation begins at a potential of about 210 mV lower on such electrodes than the pure platinum electrode (100 %mol Pt. But for electrode containing low quantity of Pt, the surface of the coating is essentially composed of IrO2 and methanol oxidation occurs in the domain of water decomposition solely. The increase of the electrocatalytic behaviour of the electrodes containing high amount of Pt towards methanol oxidation is due to the bifunctional behaviour of the electrodes.

  11. High-yield acetonitrile | water triple phase boundary electrolysis at platinised Teflon electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Watkins, John D.; MacDonald, Stuart M.; Fordred, Paul S.; Bull, Steven D. [Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom); Gu, Yunfeng; Yunus, Kamran; Fisher, Adrian C. [Department of Chemical Engineering, University of Cambridge, New Museums Site, Pembroke Street, Cambridge CB2 3RA (United Kingdom); Bulman-Page, Philip C. [School of Chemistry, University of East Anglia, Norwich, Norfolk NR4 7TJ (United Kingdom); Marken, Frank [Department of Chemistry, University of Bath, Claverton Down, Bath BA2 7AY (United Kingdom)], E-mail: f.marken@bath.ac.uk

    2009-11-30

    A dynamic acetonitrile | aqueous electrolyte phase boundary in contact with platinised Teflon working electrodes is investigated. High concentrations of salt in the aqueous phase (2 M NaCl and 0.1 M NaClO{sub 4}) ensure immiscibility and the polar nature of acetonitrile aids the formation of a well-behaved triple phase boundary reaction zone. The one-electron oxidation of tert-butylferrocene in the organic phase without intentionally added electrolyte is studied. The limiting current for the flowing triple phase boundary process is shown to be essentially volume flow rate independent. The process is accompanied by the transfer of perchlorate from the aqueous into the organic phase and the flux of anions is shown to be approximately constant along the dynamic acetonitrile | aqueous electrolyte | platinum line interface. A high rate of conversion (close to 100%) is achieved at slow volume flow rates and at longer platinum electrodes.

  12. Amperometric biosensor for the detection of hydrogen peroxide using catalase modified electrodes in polyacrylamide.

    Science.gov (United States)

    Varma, Shailly; Mattiasson, Bo

    2005-09-23

    A simple biosensor for the detection of hydrogen peroxide in organic solvents has been developed and coupled to a flow injection analysis (FIA) system. Catalase was entrapped in polyacrylamide gel and placed on the surface of platinum (working electrode) fixed in a Teflon holder with Ag-wire (auxiliary electrode), followed by addition of filter paper soaked in KCl. The entrapped catalase gel was held on the electrode using membranes. The effects of cellulose and polytetrafluroethylene (PTFE) membranes on the electrode response towards hydrogen peroxide have been studied. The modified electrode has been used to study the detection of hydrogen peroxide in solvents like water, dimethyl sulfoxide (DMSO), and 1,4-dioxane using amperometric techniques like cyclic voltammetry (CV) and FIA. The CV of modified catalase electrode showed a broad oxidation peak at -150 mV and a clear reduction peak at -212 mV in the presence of hydrogen peroxide. Comparison of CV with hydrogen peroxide in various solvents has been carried out. The electrode showed an irreversible kinetics with DMSO as the solvent. A flow cell has been designed in order to carry on FIA studies to obtain calibration plots for hydrogen peroxide with the modified electrode. The calibration plots in several solvents such as water, dimethyl sulfoxide, 1,4-dioxane have been obtained. The throughput of the enzyme electrode was 10 injections per hour. Due to the presence of membrane the response time of the electrode is concentration dependent.

  13. Preparation of carbonaceous electrodes and evaluation of their performance by electrochemical techniques

    International Nuclear Information System (INIS)

    Sharma, H.S.; Manolkar, R.B.; Kamat, J.V.; Marathe, S.G.; Biswas, A.R.; Kulkarni, P.G.

    1994-01-01

    Carbonaceous electrodes, from glassy carbon (GC), graphite rod or graphite powder, have been prepared for coulometric and voltammetric investigation. Beaker type graphite electrode of larger surface area was used as working electrode for the analysis of uranium and plutonium in solution by coulometry. Results have shown usefulness of the electrode for both uranium and plutonium analysis. Thus the graphite electrode can be used in place of mercury for uranium analysis and in place of platinum gauze for plutonium analysis. GC electrode ( from French and Indian material ), graphite or carbon paste electrode of smaller surface area prepared here have also been found to give satisfactory performance as could be observed from cyclic voltammetric (cv) patterns for standard K 9 Fe(CN) 6 /K 4 Fe(CN) 6 redox system. Especially the GC electrode, (French) polished to 1μ finish with diamond paste gave very low values (1μ amp.) of background current in 1M KCl and the difference in cathodic and anodic peak potentials (δE values) was close to 60 mV from one electron transfer. Therefore the electrode can be used for various types of electrochemical studies relating to redox potentials, reaction mechanism, kinetic parameters etc. of different electrode processes. (author). 20 refs., 3 tabs., 10 figs., 8 photographs

  14. Immobilization of flavin adenine dinucleotide (FAD) onto carbon cloth and its application as working electrode in an electroenzymatic bioreactor.

    Science.gov (United States)

    Jayabalan, R; Sathishkumar, M; Jeong, E S; Mun, S P; Yun, S E

    2012-11-01

    A high porosity carbon cloth with immobilized FAD was employed as working electrode in electrochemical NADH-regeneration procedure. Carbon cloth was oxidized with hot acids to create surface carboxyl group and then coupled by adenine amino group of FAD with carbodiimide in the presence of N-hydroxysulfosuccinimide. The bioelectrocatalytic NADH-regeneration was coupled to the conversion of achiral substrate pyruvate into chiral product l-lactate by l-lactate dehydrogenase (l-LDH) within the same reactor. The conversion was completed at 96h in bioreactor with FAD-modified carbon cloth, resulting in about 6mM of l-lactate from 10mM of pyruvate. While with bare carbon cloth, the yield at 120h was around 5mM. Immobilized FAD on the surface of carbon cloth electrode facilitated it to carry electrons from electrode to electron transfer enzymes; thereby NADH-regeneration was accelerated to drive the enzymatic reaction efficiently. Copyright © 2012 Elsevier Ltd. All rights reserved.

  15. Engineered porous silicon counter electrodes for high efficiency dye-sensitized solar cells.

    Science.gov (United States)

    Erwin, William R; Oakes, Landon; Chatterjee, Shahana; Zarick, Holly F; Pint, Cary L; Bardhan, Rizia

    2014-06-25

    In this work, we demonstrate for the first time, the use of porous silicon (P-Si) as counter electrodes in dye-sensitized solar cells (DSSCs) with efficiencies (5.38%) comparable to that achieved with platinum counter electrodes (5.80%). To activate the P-Si for triiodide reduction, few layer carbon passivation is utilized to enable electrochemical stability of the silicon surface. Our results suggest porous silicon as a promising sustainable and manufacturable alternative to rare metals for electrochemical solar cells, following appropriate surface modification.

  16. Bio-inspired routes for synthesizing efficient nanoscale platinum electrocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Jennifer N. [Univ. of California, San Diego, CA (United States); Wang, Joseph [Univ. of California, San Diego, CA (United States)

    2014-08-31

    The overall objective of the proposed research is to use fundamental advances in bionanotechnology to design powerful platinum nanocrystal electrocatalysts for fuel cell applications. The new economically-viable, environmentally-friendly, bottom-up biochemical synthetic strategy will produce platinum nanocrystals with tailored size, shape and crystal orientation, hence leading to a maximum electrochemical reactivity. There are five specific aims to the proposed bio-inspired strategy for synthesizing efficient electrocatalytic platinum nanocrystals: (1) isolate peptides that both selectively bind particular crystal faces of platinum and promote the nucleation and growth of particular nanocrystal morphologies, (2) pattern nanoscale 2-dimensional arrays of platinum nucleating peptides from DNA scaffolds, (3) investigate the combined use of substrate patterned peptides and soluble peptides on nanocrystal morphology and growth (4) synthesize platinum crystals on planar and large-area carbon electrode supports, and (5) perform detailed characterization of the electrocatalytic behavior as a function of catalyst size, shape and morphology. Project Description and Impact: This bio-inspired collaborative research effort will address key challenges in designing powerful electrocatalysts for fuel cell applications by employing nucleic acid scaffolds in combination with peptides to perform specific, environmentally-friendly, simultaneous bottom-up biochemical synthesis and patterned assembly of highly uniform and efficient platinum nanocrystal catalysts. Bulk synthesis of nanoparticles usually produces a range of sizes, accessible catalytic sites, crystal morphologies, and orientations, all of which lead to inconsistent catalytic activities. In contrast, biological systems routinely demonstrate exquisite control over inorganic syntheses at neutral pH and ambient temperature and pressures. Because the orientation and arrangement of the templating biomolecules can be precisely

  17. Platinum metals in the environment

    Energy Technology Data Exchange (ETDEWEB)

    Zereini, Fathi [Frankfurt Univ. (Germany). Dept. of Environmental Analytical Chemistry; Wiseman, Clare L.S. (ed.) [Toronto Univ. (Canada). School of the Environment

    2015-03-01

    This book contains the five chapters with the following topics: 1. SOURCES OF PGE EMISSIONS ELEMENTS: Sources of Platinum Group Elements (PGE) in the Environment; Impact of Platinum Group Element Emissions from Mining and Production Activities. 2. ANALYTICAL METHODS FOR THE DETERMINATION OF PGE IN BIOLOGICAL AND ENVIRONMENTAL MATRICES: Appraisal of Biosorption for Recovery, Separation and Determination of Platinum, Palladium and Rhodium in Environmental Samples; On the Underestimated Factors Influencing the Accuracy of Determination of Pt and Pd by Electrothermal Atomic Absorption Spectrometry in Road Dust Samples; Application of Solid Sorbents for Enrichment and Separation of Platinum Metal Ions; Voltammetric Analysis of Platinum in Environmental Matrices; Speciation Analysis of Chloroplatinates; Analysis of Platinum Group Elements in Environmental Samples: A Review. 3. OCCURRENCE, CHEMICAL BEHAVIOR AND FATE OF PGE IN THE ENVIRONMENT: Brazilian PGE Research Data Survey on Urban and Roadside Soils; Platinum, Palladium and Rhodium in a Bavarian Roadside Soil; Increase of Platinum Group Element Concentrations in Soils and Airborne Dust During the Period of Vehicular Exhaust Catalysts Introduction; Platinum-Group Elements in Urban Fluvial Bed Sediments-Hawaii; Long-Term Monitoring of Palladium and Platinum Contents in Road Dust of the City of Munich, Germany; Characterization of PGEs and Other Elements in Road Dusts and Airborne Particles in Houston, Texas; Accumulation and Distribution of Pt and Pd in Roadside Dust, Soil and Vegetation in Bulgaria; Increase of the Environmental Pt Concentration in the Metropolitan Area of Mexico City Associated to the Use of Automobile Catalytic Converters; Solubility of Emitted Platinum Group Elements (Pt, Pd and Rh) in Airborne Particulate Matter (PM10) in the Presence of Organic Complexing Agents; The Influence of Anionic Species (Cl{sup -}, NO{sub 3}{sup -}, SO{sub 4}{sup 2-}) on the Transformation and Solubility of Platinum in

  18. Standard test method for determining plutonium by controlled-potential coulometry in H2SO4 at a platinum working electrode

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1990-01-01

    1.1 This test method covers the determination of milligram quantities of plutonium in unirradiated uranium-plutonium mixed oxide having a U/Pu ratio range of 0.1 to 10. This test method is also applicable to plutonium metal, plutonium oxide, uranium-plutonium mixed carbide, various plutonium compounds including fluoride and chloride salts, and plutonium solutions. 1.2 The recommended amount of plutonium for each aliquant in the coulometric analysis is 5 to 10 mg. Precision worsens for lower amounts of plutonium, and elapsed time of electrolysis becomes impractical for higher amounts of plutonium. 1.3 The values stated in SI units are to be regarded as standard. No other units are to be regarded as standard. 1.4 This standard does not purport to address all of the safety concens, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precaution...

  19. New method for characterizing electron mediators in microbial systems using a thin-layer twin-working electrode cell.

    Science.gov (United States)

    Hassan, Md Mahamudul; Cheng, Ka Yu; Ho, Goen; Cord-Ruwisch, Ralf

    2017-01-15

    Microbial biofilms are significant ecosystems where the existence of redox gradients drive electron transfer often via soluble electron mediators. This study describes the use of two interfacing working electrodes (WEs) to simulate redox gradients within close proximity (250µm) for the detection and quantification of electron mediators. By using a common counter and reference electrode, the potentials of the two WEs were independently controlled to maintain a suitable "voltage window", which enabled simultaneous oxidation and reduction of electron mediators as evidenced by the concurrent anodic and cathodic currents, respectively. To validate the method, the electrochemical properties of different mediators (hexacyanoferrate, HCF, riboflavin, RF) were characterized by stepwise shifting the "voltage window" (ranging between 25 and 200mV) within a range of potentials after steady equilibrium current of both WEs was established. The resulting differences in electrical currents between the two WEs were recorded across a defined potential spectrum (between -1V and +0.5V vs. Ag/AgCl). Results indicated that the technique enabled identification (by the distinct peak locations at the potential scale) and quantification (by the peak of current) of the mediators for individual species as well as in an aqueous mixture. It enabled a precise determination of mid-potentials of the externally added mediators (HCF, RF) and mediators produced by pyocyanin-producing Pseudomonas aeruginosa (WACC 91) culture. The twin working electrode described is particularly suitable for studying mediator-dependent microbial electron transfer processes or simulating redox gradients as they exist in microbial biofilms. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Electronic structure of low work function electrodes modified by C{sub 16}H{sub 33}SH

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyunbok [Department of Polymer Science and Engineering, University of Massachusetts, Amherst, MA, 01003 (United States); Cho, Sang Wan, E-mail: dio8027@yonsei.ac.kr [Department of Physics, Yonsei University, 1 Yonseidae-gil, Wonju-si, Gangwon-do, 220-710 (Korea, Republic of); Park, Sang Han; Cho, Mann-Ho; Yi, Yeonjin [Institute of Physics and Applied Physics, Yonsei University, 50 Yonsei-ro, Seodaemoon-Gu, Seoul, 120-749 (Korea, Republic of)

    2014-10-15

    Highlights: • The electronic structure of pentacene/C{sub 16}H{sub 33}SH/Au is investigated. • The work function of Au is significantly decreased with C{sub 16}H{sub 33}SH treatment. • The reduced work function is attributed to its permanent dipole moment. - Abstract: Organic and printed electronics technologies require electrodes with low work functions to facilitate the transport of electrons in and out of various optoelectronic devices. We show that the surface modifier of 1-hexadecanethiol reduces the work function of conductors using in situ ultraviolet photoemission spectroscopy, and we combine experimental and theoretical methods to investigate the origin of the work function changes. The interfacial electronic structures of pentacene/1-hexadecanethiol/Au were investigated via in situ ultraviolet photoemission spectroscopy and X-ray photoemission spectroscopy in order to understand the change in the carrier injection barrier and chemical reactions upon surface modification. Theoretical calculations using density functional theory were also performed to understand the charge distribution of 1-hexadecanethiol, which affects the reduction of the work function. The 1-hexadecanethiol surface modifier is processed in air from solution, providing an appealing alternative to chemically-reactive low-work-function metals.

  1. Oscillatory instabilities in the electrooxidation of borohydride on platinum

    Energy Technology Data Exchange (ETDEWEB)

    Machado, Eduardo G.; Varela, Hamilton, E-mail: varela@iqsc.usp.br [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Instituto de Quimica

    2014-03-15

    The borohydride ion has been pointed as a promising alternative fuel. Most of the investigation on its electrochemistry is devoted to the electrocatalytic aspects of its electrooxidation on platinum and gold surfaces. Besides the known kinetic limitations and intricate mechanism, our Group has recently found the occurrence of two regions of bi-stability and autocatalysis in the electrode potential during the open circuit interaction of borohydride and oxidized platinum surfaces. Following this previous contribution, the occurrence of more complicated phenomena is here presented: namely the presence of electrochemical oscillations during the electrooxidation of borohydride on platinum in alkaline media. Current oscillations were found to be associated to two distinct instability windows and characterized in the resistance-potential parameter plane. The dynamic features of such oscillations suggest the existence of distinct mechanisms according to the potential region. Previously published results obtained under non-oscillatory regime were used to give some hints on the surface chemistry behind the observed dynamics. (author)

  2. Electrochemical behaviour of platinum in hydrogen peroxide solution (1963)

    International Nuclear Information System (INIS)

    Prost, G.H.

    1963-06-01

    The relative stability of hydrogen peroxide in aqueous solution at 25 deg. C, allows its amperometric determination from the theory, using either its cathodic reduction or its anodic oxidation. The cathodic reduction yields a wave on a platinum electrode only when some oxygen is present in the solution. It cannot, therefore, be used for electrochemical determination. On the other hand, the anodic oxidation on platinum produces a wave which might be used. However, a passivation of platinum occurs at the same time. This passivation process is studied by means of potentio-kinetic, potentio-static, intensio-static curves and of pH measurements in the vicinity of the anode. A mechanism for passivation is presented, which takes into account the role of hydrogen peroxide as a reducing agent. This passivation rules out any analytical application of the oxidation reaction of hydrogen peroxide. (author) [fr

  3. Single-Atom Catalyst of Platinum Supported on Titanium Nitride for Selective Electrochemical Reactions.

    Science.gov (United States)

    Yang, Sungeun; Kim, Jiwhan; Tak, Young Joo; Soon, Aloysius; Lee, Hyunjoo

    2016-02-05

    As a catalyst, single-atom platinum may provide an ideal structure for platinum minimization. Herein, a single-atom catalyst of platinum supported on titanium nitride nanoparticles were successfully prepared with the aid of chlorine ligands. Unlike platinum nanoparticles, the single-atom active sites predominantly produced hydrogen peroxide in the electrochemical oxygen reduction with the highest mass activity reported so far. The electrocatalytic oxidation of small organic molecules, such as formic acid and methanol, also exhibited unique selectivity on the single-atom platinum catalyst. A lack of platinum ensemble sites changed the reaction pathway for the oxygen-reduction reaction toward a two-electron pathway and formic acid oxidation toward direct dehydrogenation, and also induced no activity for the methanol oxidation. This work demonstrates that single-atom platinum can be an efficient electrocatalyst with high mass activity and unique selectivity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Barium Staminate as Semiconductor Working Electrodes for Dye-Sensitized Solar Cells

    Directory of Open Access Journals (Sweden)

    Fu-an Guo

    2010-01-01

    Full Text Available Dye-sensitized solar cells (DSSCs are fabricated with perovskite-type BaSnO3 as the photoelectrode materials. Different preparation methods including coprecipitation, hydrothermal, and solid state reaction are employed to synthesize BaSnO3 particles to optimize the photoelectric activities of electrode materials. The photoelectric properties of BaSnO3 particles and the performances of DSSCs are investigated by surface photovoltage spectroscopy and current-voltage measurements. The light-to-electricity conversion of 1.1% is preliminarily reached on the DSSC made of the coprecipitation-derived BaSnO3 particles. Large current density of hole injection into the HOMO level of N719 dye from the valence band of BaSnO3 and reduced photogenerated charge recombination in BaSnO3 could be responsible for the observed solar cell performance of the DSSC fabricated from the coprecipitation-derived BaSnO3 particles.

  5. Platinum-group elements

    Science.gov (United States)

    Zientek, Michael L.; Loferski, Patricia J.; Parks, Heather L.; Schulte, Ruth F.; Seal, Robert R.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    The platinum-group elements (PGEs)—platinum, palladium, rhodium, ruthenium, iridium, and osmium—are metals that have similar physical and chemical properties and tend to occur together in nature. PGEs are indispensable to many industrial applications but are mined in only a few places. The availability and accessibility of PGEs could be disrupted by economic, environmental, political, and social events. The United States net import reliance as a percentage of apparent consumption is about 90 percent.PGEs have many industrial applications. They are used in catalytic converters to reduce carbon monoxide, hydrocarbon, and nitrous oxide emissions in automobile exhaust. The chemical industry requires platinum or platinum-rhodium alloys to manufacture nitric oxide, which is the raw material used to manufacture explosives, fertilizers, and nitric acid. In the petrochemical industry, platinum-supported catalysts are needed to refine crude oil and to produce aromatic compounds and high-octane gasoline. Alloys of PGEs are exceptionally hard and durable, making them the best known coating for industrial crucibles used in the manufacture of chemicals and synthetic materials. PGEs are used by the glass manufacturing industry in the production of fiberglass and flat-panel and liquid crystal displays. In the electronics industry, PGEs are used in computer hard disks, hybridized integrated circuits, and multilayer ceramic capacitors.Aside from their industrial applications, PGEs are used in such other fields as health, consumer goods, and finance. Platinum, for example, is used in medical implants, such as pacemakers, and PGEs are used in cancer-fighting drugs. Platinum alloys are an ideal choice for jewelry because of their white color, strength, and resistance to tarnish. Platinum, palladium, and rhodium in the form of coins and bars are also used as investment commodities, and various financial instruments based on the value of these PGEs are traded on major exchanges

  6. On the mobility of carbon-supported platinum nanoparticles towards unveiling cathode degradation in water electrolysis

    Science.gov (United States)

    Paciok, Paul; Schalenbach, Maximilian; Carmo, Marcelo; Stolten, Detlef

    2017-10-01

    This study investigates the influence of the hydrogen evolution reaction (HER) overpotential on the mobility of carbon-supported platinum particles. The migration of the platinum over the carbon support was analyzed by means of identical location transmission electron microscopy (IL-TEM). While at potentials of 0.1 and 0 V vs. reversible hydrogen electrode (RHE), no changes to the Pt/C material were observed. With a decrease of the overpotential to -0.1 V vs. RHE, an increase in the quantity of migrating platinum particles took place. At -0.2 V vs. RHE, a further rise in the particle migration was observed. The effect of the overpotential on the migration was explained by a higher hydrogen generation rate, the formation of a hydrogen monolayer on the platinum and the resulting changes of the platinum support distance. The mechanisms revealed in this study could describe a relevant source of degradation of PEM water electrolyzers.

  7. Point defects in platinum

    International Nuclear Information System (INIS)

    Piercy, G.R.

    1960-01-01

    An investigation was made of the mobility and types of point defect introduced in platinum by deformation in liquid nitrogen, quenching into water from 1600 o C, or reactor irradiation at 50 o C. In all cases the activation energy for motion of the defect was determined from measurements of electrical resistivity. Measurements of density, hardness, and x-ray line broadening were also made there applicable. These experiments indicated that the principal defects remaining in platinum after irradiation were single vacant lattice sites and after quenching were pairs of vacant lattice sites. Those present after deformation In liquid nitrogen were single vacant lattice sites and another type of defect, perhaps interstitial atoms. (author)

  8. Oxygen Reduction Reaction Activity of Platinum Thin Films with Different Densities

    Energy Technology Data Exchange (ETDEWEB)

    Ergul, Busra; Begum, Mahbuba; Kariuki, Nancy; Myers, Deborah J.; Karabacak, Tansel

    2017-08-24

    Platinum thin films with different densities were grown on glassy carbon electrodes by high pressure sputtering deposition and evaluated as oxygen reduction reaction catalysts for polymer electrolyte fuel cells using cyclic voltammetry and rotating disk electrode techniques in aqueous perchloric acid electrolyte. The electrochemically active surface area, ORR mass activity (MA) and specific activity (SA) of the thin film electrodes were obtained. MA and SA were found to be higher for low-density films than for high-density film.

  9. Electrochemical and microstructural characterization of platinum supported on glassy carbon

    Directory of Open Access Journals (Sweden)

    Terzić Sanja

    2007-01-01

    Full Text Available The effect of the electrochemical oxidation of glassy carbon on the deposition of platinum particles and the electrocatalytic activity of platinum supported on oxidized glassy carbon were studied for methanol oxidation in H2SO4 solution. Platinum was potentiostatically deposited from H2SO4 + 6mM H2PtCl6 solution. Glassy carbon was anodically polarized in 1 M NaOH at 1.41 V (SCE for 35 and 95 s and in 0.5 M H2SO4 at 2V (SCE for 35; 95 s and 2.25 V for 35 and 95 s. Electrochemical treatment of the GC support leads to a better distribution of platinum on the substrate and has remarkable effect on the activity. The activity of the Pt/GCox electrode for methanol oxidation is larger than that of polycrystalline Pt and by more than one order of magnitude larger than that of a Pt/GC electrode. This increase in activity indicates the pronounced role of the organic residues of the GC support on the properties of Pt particles deposited on glassy carbon.

  10. Platinum-Bismuth Bimetallic Catalysts: Synthesis, Characterization and Applications

    OpenAIRE

    Saucedo, Jose A, Jr; Xiao, Yang; Varma, Arvind

    2015-01-01

    Bimetallic catalysts have been explored and shown to exhibit unique characteristics which are not present in monometallic catalysts. Platinum is well known as an effective catalyst for oxidation and reduction reactions, and it can be made more effective when bismuth is introduced as a promotor. Thus, the effectiveness of the Pt-Bi catalyst was demonstrated in prior work. What is not clear, however, is the mechanism behind the catalyst function; why addition of bismuth to platinum decreases de...

  11. Work function tuning of tin-doped indium oxide electrodes with solution-processed lithium fluoride

    Energy Technology Data Exchange (ETDEWEB)

    Ow-Yang, C.W., E-mail: cleva@sabanciuniv.edu [Materials Science and Engineering Program, Sabanci University, Orhanli, Tuzla, 34956 Istanbul (Turkey); Nanotechnology Application Center, Sabanci University, Orhanli, Tuzla, 34956 Istanbul (Turkey); Jia, J. [Graduate School of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo, Sagamihara, Kanagawa 252-5258 (Japan); Aytun, T. [Materials Science and Engineering Program, Sabanci University, Orhanli, Tuzla, 34956 Istanbul (Turkey); Zamboni, M.; Turak, A. [Department of Engineering Physics, McMaster University, Hamilton, Ontario L8S 4L8 (Canada); Saritas, K. [Materials Science and Engineering Program, Sabanci University, Orhanli, Tuzla, 34956 Istanbul (Turkey); Shigesato, Y. [Graduate School of Science and Engineering, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo, Sagamihara, Kanagawa 252-5258 (Japan)

    2014-05-30

    Solution-processed lithium fluoride (sol-LiF) nanoparticles synthesized in polymeric micelle nanoreactors enabled tuning of the surface work function of tin-doped indium oxide (ITO) films. The micelle reactors provided the means for controlling surface coverage by progressively building up the interlayer through alternating deposition and plasma etch removal of the polymer. In order to determine the surface coverage and average interparticle distance, spatial point pattern analysis was applied to scanning electron microscope images of the nanoparticle dispersions. The work function of the sol-LiF modified ITO, obtained from photoelectron emission yield spectroscopy analysis, was shown to increase with surface coverage of the sol-LiF particles, suggesting a lateral depolarization effect. Analysis of the photoelectron emission energy distribution in the near threshold region revealed the contribution of surface states for surface coverage in excess of 14.1%. Optimization of the interfacial barrier was achieved through contributions from both work function modification and surface states. - Highlights: • Work function of indium tin oxide increased with LiF nanoparticle coverage. • Work function was analyzed via photoelectron emission yield (PEYS). • At higher surface coverage, the energy distribution of PEYS increased. • Pre-threshold increase in PEYS consistent with emission from surface states.

  12. The development of a micropatterned electrode for studies of zinc electrodeposition

    Energy Technology Data Exchange (ETDEWEB)

    Sutija, Dave P. [Univ. of California, Berkeley, CA (United States); Muller, Rolf H. [Univ. of California, Berkeley, CA (United States); Tobias, Charles W. [Univ. of California, Berkeley, CA (United States)

    1986-12-01

    A micropatterned electrode was prepared for the study of electrocrystallization. Using microphotolithography, in conjunction with evaporation and pulse electrodeposition of thin films, a set of artificially roughened electrodes with hemispherical surface features five microns in diameter was developed. Voltammetric studies were conducted to determine the best electrode material. Gold, platinum, and various carbon surfaces were evaluated for zinc nucleation density and hydrogen overpotential. Surface homogeneity was examined by both light and scanning electron microscopy. Gold was determined to possess the best combination of material properties: chemical inertness, low melting point, and a high work function allowing underpotential deposition of zinc which reduces the rate of hydrogen evolution. Stripping coulometry was employed to determine zinc limiting currents, and evaluate effective diffusion coefficients in concentrated zinc chloride solutions. Although the method worked well for dilute zinc chloride and copper sulfate solutions, it failed at higher current densities; the emergence of surface roughness obscured actual limiting current plateaus.

  13. Preparation and characterization of poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) composite thin films highly loaded with platinum nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Chao-Ching, E-mail: ccchang@tku.edu.tw [Department of Chemical and Materials Engineering, Tamkang University, No. 151, Yingzhuan Rd., Danshui Dist., New Taipei City 25137, Taiwan (China); Energy and Opto-Electronic Materials Research Center, Tamkang University, No. 151, Yingzhuan Rd., Danshui Dist., New Taipei City 25137, Taiwan (China); Jiang, Ming-Tai [Department of Chemical and Materials Engineering, Tamkang University, No. 151, Yingzhuan Rd., Danshui Dist., New Taipei City 25137, Taiwan (China); Chang, Chen-Liang; Lin, Cheng-Lan [Department of Chemical and Materials Engineering, Tamkang University, No. 151, Yingzhuan Rd., Danshui Dist., New Taipei City 25137, Taiwan (China); Energy and Opto-Electronic Materials Research Center, Tamkang University, No. 151, Yingzhuan Rd., Danshui Dist., New Taipei City 25137, Taiwan (China)

    2011-06-15

    Research highlights: {yields} Nano-sized and mono-dispersed Pt nanoparticles were synthesized by a polyol method. {yields} A thin film of PEDOT:PSS loaded with high concentration of Pt nanoparticles has been prepared. {yields} The PEDOT:PSS-Pt modified electrode has good potential to serve as a counter electrode in DSSC. - Abstract: In this work, we propose a simple and efficient, low-temperature ({approx}120 deg. C) process to prepare transparent thin films of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) loaded with high concentration (up to 22.5 wt%) of platinum (Pt) nanoparticles. Firstly, an improved polyol method was modified to synthesize nano-sized ({approx}5 nm) and mono-dispersed Pt particles. These nanoparticles were incorporated into the matrix of PEDOT:PSS thin films via a spin coating/drying procedure. The electrochemical activities of the PEDOT:PSS thin film modified electrodes with respect to the I{sup -}/I{sub 3}{sup -} redox reactions were investigated. It was found that the modified electrode of PEDOT:PSS thin film containing 22.5 wt% Pt exhibited the electrochemical activity comparable to the conventional Pt thin film electrode, suggesting that this electrode has good potential to serve as a counter electrode in dye-sensitized solar cells.

  14. Alkali metal-refractory metal biphase electrode for AMTEC

    Science.gov (United States)

    Williams, Roger M. (Inventor); Bankston, Clyde P. (Inventor); Cole, Terry (Inventor); Khanna, Satish K. (Inventor); Jeffries-Nakamura, Barbara (Inventor); Wheeler, Bob L. (Inventor)

    1989-01-01

    An electrode having increased output with slower degradation is formed of a film applied to a beta-alumina solid electrolyte (BASE). The film comprises a refractory first metal M.sup.1 such as a platinum group metal, suitably platinum or rhodium, capable of forming a liquid or a strong surface adsorption phase with sodium at the operating temperature of an alkali metal thermoelectric converter (AMTEC) and a second refractory metal insoluble in sodium or the NaM.sup.1 liquid phase such as a Group IVB, VB or VIB metal, suitably tungsten, molybdenum, tantalum or niobium. The liquid phase or surface film provides fast transport through the electrode while the insoluble refractory metal provides a structural matrix for the electrode during operation. A trilayer structure that is stable and not subject to deadhesion comprises a first, thin layer of tungsten, an intermediate co-deposited layer of tungsten-platinum and a thin surface layer of platinum.

  15. Textured strontium titanate layers on platinum by atomic layer deposition

    International Nuclear Information System (INIS)

    Blomberg, T.; Anttila, J.; Haukka, S.; Tuominen, M.; Lukosius, M.; Wenger, Ch.; Saukkonen, T.

    2012-01-01

    Formation of textured strontium titanate (STO) layers with large lateral grain size (0.2–1 μm) and low X-ray reflectivity roughness (∼ 1.36 nm) on Pt electrodes by industry proven atomic layer deposition (ALD) method is demonstrated. Sr(t-Bu 3 Cp) 2 , Ti(OMe) 4 and O 3 precursors at 250 °C were used to deposit Sr rich STO on Pt/Ti/SiO 2 /Si ∅200 mm substrates. After crystallization post deposition annealing at 600 °C in air, most of the STO grains showed a preferential orientation of the {001} plane parallel to the substrate surface, although other orientations were also present. Cross sectional and plan view transmission electron microscopy and electron diffraction analysis revealed more than an order of magnitude larger lateral grain sizes for the STO compared to the underlying multicrystalline {111} oriented platinum electrode. The combination of platinum bottom electrodes with ALD STO(O 3 ) shows a promising path towards the formation of single oriented STO film. - Highlights: ► Amorphous strontium titanate (STO) on platinum formed a textured film after annealing. ► Single crystal domains in 60 nm STO film were 0.2–1 μm wide. ► Most STO grains were {001} oriented.

  16. Analytical expression for the tunnel current through the redox-mediated tunneling contact in the case of the adiabatic electron transfer at one of the working electrodes and any possible type of the electron transfer at the other electrode.

    Science.gov (United States)

    Medvedev, Igor G

    2017-11-21

    We study the tunnel current through a one-level redox molecule immersed into the electrolyte solution for the case when the coupling of the molecule to one of the working electrodes is strong while it is arbitrary to the other electrode. Using the Feynman-Vernon influence functional theory and the perturbation expansion of the effective action of the classical oscillator coupled both to the valence level of the redox molecule and to the thermal bath representing the classical fluctuations of the polarization of the solvent, we obtain, following the canonical way, the Langevin equation for the oscillator. It is found that for the aqueous electrolyte solution, the damping and the stochastic forces which arise due to the tunnel current are much smaller than those due to the thermal bath and therefore can be neglected. We estimate the higher-order corrections to the effective action and show that the Langevin dynamics takes place in this case for arbitrary parameters of the tunneling junction under the condition of the strong coupling of the redox molecule to one of the working electrodes. Then the steady-state coordinate distribution function of the oscillator resulting from the corresponding Fokker-Planck equation is the Boltzmann distribution function which is determined by the adiabatic free energy surface arising from the mean current-induced force. It enables us to obtain the expression for the tunnel current in the case when the coupling of the redox molecule to one of the working electrodes is strong while it is arbitrary to the other electrode.

  17. Impedance study of tea with added taste compounds using conducting polymer and metal electrodes.

    Science.gov (United States)

    Dhiman, Mopsy; Kapur, Pawan; Ganguli, Abhijit; Singla, Madan Lal

    2012-09-01

    In this study the sensing capabilities of a combination of metals and conducting polymer sensing/working electrodes for tea liquor prepared by addition of different compounds using an impedance mode in frequency range 1 Hz-100 KHz at 0.1 V potential has been carried out. Classification of six different tea liquor samples made by dissolving various compounds (black tea liquor + raw milk from milkman), (black tea liquor + sweetened clove syrup), (black tea liquor + sweetened ginger syrup), (black tea liquor + sweetened cardamom syrup), (black tea liquor + sweet chocolate syrup) and (black tea liquor + vanilla flavoured milk without sugar) using six different working electrodes in a multi electrode setup has been studied using impedance and further its PCA has been carried out. Working electrodes of Platinum (Pt), Gold (Au), Silver (Ag), Glassy Carbon (GC) and conducting polymer electrodes of Polyaniline (PANI) and Polypyrrole (PPY) grown on an ITO surface potentiostatically have been deployed in a three electrode set up. The impedance response of these tea liquor samples using number of working electrodes shows a decrease in the real and imaginary impedance values presented on nyquist plots depending upon the nature of the electrode and amount of dissolved salts present in compounds added to tea liquor/solution. The different sensing surfaces allowed a high cross-selectivity in response to the same analyte. From Principal Component Analysis (PCA) plots it was possible to classify tea liquor in 3-4 classes using conducting polymer electrodes; however tea liquors were well separated from the PCA plots employing the impedance data of both conducting polymer and metal electrodes.

  18. Near-Electrode Imager

    Energy Technology Data Exchange (ETDEWEB)

    Rathke, Jerome W.; Klingler, Robert J.; Woelk, Klaus; Gerald, Rex E.,II

    1999-05-01

    An apparatus, near-electrode imager, for employing nuclear magnetic resonance imaging to provide in situ measurements of electrochemical properties of a sample as a function of distance from a working electrode. The near-electrode imager use the radio frequency field gradient within a cylindrical toroid cavity resonator to provide high-resolution nuclear magnetic resonance spectral information on electrolyte materials.

  19. Developments in platinum anticancer drugs

    Science.gov (United States)

    Tylkowski, Bartosz; Jastrząb, Renata; Odani, Akira

    2018-01-01

    Platinum compounds represent one of the great success stories of metals in medicine. Following the unexpected discovery of the anticancer activity of cisplatin (Fig. 1) in 1965 by Prof. Rosenberg [1], a large number of its variants have been prepared and tested for their ability to kill cancer cells and inhibit tumor growth. Although cisplatin has been in use for over four decades, new and more effective platinum-based therapeutics are finally on the horizon. A wide introduction to anticancer studies is given by the authors of the previous chapter. This chapter aims at providing the readers with a comprehensive and in-depth understanding of recent developments of platinum anticancer drugs and to review the state of the art. The chapter is divided into two parts. In the first part we present a historical aspect of platinum and its complexes, while in the second part we give an overview of developments in the field of platinum anticancer agents.

  20. Large-area functionalized CVD graphene for work function matched transparent electrodes

    Science.gov (United States)

    Bointon, Thomas H.; Jones, Gareth F.; de Sanctis, Adolfo; Hill-Pearce, Ruth; Craciun, Monica F.; Russo, Saverio

    2015-11-01

    The efficiency of flexible photovoltaic and organic light emitting devices is heavily dependent on the availability of flexible and transparent conductors with at least a similar workfunction to that of Indium Tin Oxide. Here we present the first study of the work function of large area (up to 9 cm2) FeCl3 intercalated graphene grown by chemical vapour deposition on Nickel, and demonstrate values as large as 5.1 eV. Upon intercalation, a charge density per graphene layer of 5 ṡ 1013 ± 5 ṡ 1012 cm-2 is attained, making this material an attractive platform for the study of plasmonic excitations in the infrared wavelength spectrum of interest to the telecommunication industry. Finally, we demonstrate the potential of this material for flexible electronics in a transparent circuit on a polyethylene naphthalate substrate.

  1. An improved method for direct estimation of free cyanide in drinking water by Ion Chromatography-Pulsed Amperometry Detection (IC-PAD) on gold working electrode.

    Science.gov (United States)

    Kumar Meher, Alok; Labhsetwar, Nitin; Bansiwal, Amit

    2018-02-01

    In the present work a fast, reliable and safe Ion Exchange Chromatography-Pulsed Amperometry Detection (IC-PAD) method for direct determination of free cyanide in drinking water has been reported. To the best of our knowledge for the first time we are reporting the application of Gold working electrode for detection of free cyanide in a chromatography system. The system shows a wide linear range up to 8000µg/L. The electrode was found to have improved sensitivity and selectivity in the presence of interfering ions. The detection limit of the system was calculated to be 2µg/L. Long term evaluation of the electrode was found to be stable. Reproducible results were obtained from analysis of drinking water samples with recoveries of 98.3-101.2% and Relative Standard Deviations (RSD) of cyanide in drinking water. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Enhancing the efficiency of dye-sensitized solar cells by adding diatom frustules into TiO{sub 2} working electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Der-Ray, E-mail: derray@mail.ndhu.edu.tw; Jiang, Yan-Jang; Liou, Run-Lin; Chen, Chih-Han; Chen, Yi-An; Tsai, Chih-Hung, E-mail: cht@mail.ndhu.edu.tw

    2015-08-30

    Graphical abstract: - Highlights: • High-speed centrifugal processing and sedimentation-rate separation techniques were used to obtain diatom frustules. • Diatom frustules were added into TiO{sub 2} paste to prepare a TiO{sub 2}-diatom paste mixture. • TiO{sub 2}-diatom paste mixture was used to fabricate working electrodes for DSSCs. • TiO{sub 2}-diatom electrodes improved the light-trapping effect and DSSC efficiency. • DSSCs with using the TiO{sub 2}-diatom electrode exhibited a 38% increase in efficiency. - Abstract: In this study, diatom frustules were added into TiO{sub 2} paste to prepare a TiO{sub 2}-diatom paste mixture. Spin-coating and high-temperature sintering techniques were then used to fabricate working electrodes for dye-sensitized solar cells (DSSCs). Mixing the diatom frustules with the TiO{sub 2} paste improved the light-trapping effect and scattering properties of the incident light in the TiO{sub 2}-diatom working electrodes, thereby enhancing the power conversion efficiency of the DSSCs. In this study, a high-speed centrifugal processing technology and sedimentation-rate separation techniques were first used to obtain the diatom frustules, which were then mixed with the TiO{sub 2} paste at a weight ratio of 1:50; a spin-coating technique was then used to fabricate the working electrodes. Finally, a high-temperature sintering process (500 °C) was performed. In this study, optical microscopy, scanning electron microscopy, atomic force microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and a surface profiler and spectrometer were used to analyze the characteristics of the working electrodes. The TiO{sub 2} or TiO{sub 2}-diatom working electrodes were prepared under various spin-coating conditions for fabricating and analyzing the characteristics of the DSSCs. The results indicated that under identical conditions, the power conversion efficiency of the DSSCs was 3.81% when coated three times with a conventional TiO{sub 2

  3. Carbon aerogel electrodes for direct energy conversion

    Science.gov (United States)

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

    1997-01-01

    A direct energy conversion device, such as a fuel cell, using carbon aerogel electrodes, wherein the carbon aerogel is loaded with a noble catalyst, such as platinum or rhodium and soaked with phosphoric acid, for example. A separator is located between the electrodes, which are placed in a cylinder having plate current collectors positioned adjacent the electrodes and connected to a power supply, and a pair of gas manifolds, containing hydrogen and oxygen positioned adjacent the current collectors. Due to the high surface area and excellent electrical conductivity of carbon aerogels, the problems relative to high polarization resistance of carbon composite electrodes conventionally used in fuel cells are overcome.

  4. OFFGEL isoelectric focusing and polyacrylamide gel electrophoresis separation of platinum-binding proteins.

    Science.gov (United States)

    Mena, Ma Luz; Moreno-Gordaliza, Estefanía; Moraleja, Irene; Cañas, Benito; Gómez-Gómez, Ma Milagros

    2011-03-04

    In this work a 2D electrophoretic separation procedure able to maintain the integrity of platinum-protein bonds has been developed. The method is based on the use of sequential OFFGEL isoelectric focussing (IEF) and PAGE. A systematic study of the reagents used for PAGE, for OFFGEL-IEF separation, and post-separation treatment of gels (such as enzymatic digestion and sample preparation for MS analysis) was tackled regarding their suitability for the identification of platinum binding proteins using standard proteins incubated with cisplatin. The distribution of platinum in high and low molecular weight fractions (separated by cut-off filters) was determined by ICP-MS, which allows evaluating platinum-protein bond stability under the conditions studied. SDS-PAGE in the absence of β-mercaptoethanol or dithiotreitol preserved the platinum-protein bonds. In addition, neither the influence of the electric field during the electrophoretic separation, nor the processes of fixing, staining and destaining of proteins in the gel did result in the loss of platinum from platinum binding proteins. SDS-PAGE under non-reducing conditions provides separation of platinum-binding proteins in very narrow bands with quantitative recoveries. Different amounts of platinum-bound proteins covering the range 0.3-2.0 μg were separated and mineralised for platinum determination, showing good platinum linearity. Limits of detection for a mixture of five standard proteins incubated with cisplatin were between the range of 2.4 and 13.9 pg of platinum, which were satisfactory for their application to biological samples. Regarding OFFGEL-IEF, a denaturing solution without thiourea and without dithiotreitol is recommended. The suitability of the OFFGEL-IEF for the separation of platinum binding proteins of a kidney cytosol was demonstrated. Copyright © 2011 Elsevier B.V. All rights reserved.

  5. A pre-anodized inlaying ultrathin carbon paste electrode for simultaneous determination of uric acid and folic acid

    International Nuclear Information System (INIS)

    Huo, Jing’e; Shangguan, Enbo; Li, Quanmin

    2013-01-01

    Graphical abstract: In 0.10 mol/L PBS (pH 6.00), oxidation reaction occurred at the PAIUCPE owing to uric acid (UA) loss electrons, while oxygen dissolved in the feed was reduced at the platinum electrode. Furthermore, the effect of electrode reaction at the platinum electrode on that of working electrode is detailedly discussed. Highlights: ► The simultaneous determination of UA and FA is achieved at the PAIUCPE. ► The effect of reaction at the Pt electrode on that of working electrode is discussed. ► The effect of pH on peak currents is detailedly explained for the first time. -- Abstract: A pre-anodized inlaying ultrathin carbon paste electrode (PAIUCPE) was prepared by electrochemical pretreatment. The scanning electron microscope (SEM) was applied to characterize the surface morphology of PAIUCPE and the performance of the electrode was characterized by cyclic voltammetry (CV). The results indicated that PAIUCPE displayed excellent electrocatalysis for the oxidation of uric acid (UA) and folic acid (FA). The separated extent between the two oxidation peaks of UA and FA was 324 mV, which was enough for the simultaneous detection. In 0.10 mol/L PBS (pH 6.00), the linear scan voltammetry (LSV) response of UA and FA increased linearly with the concentration in the range of 4.0 × 10 −6 –3.5 × 10 −4 mol/L and 3.0 × 10 −6 –2.0 × 10 −4 mol/L with the detection limits of 1.1 × 10 −7 mol/L and 1.5 × 10 −7 mol/L, respectively. It was successfully used to determine UA and FA in human urine simultaneously

  6. Hydrogen Peroxide Impedimetric Detection on Poly-Ortho-Phenylenediamine Modified Platinum Disk Microelectrode

    International Nuclear Information System (INIS)

    Zainiharyati Mohd Zain; Norazreen Zakaria

    2014-01-01

    This work describes the development of hydrogen peroxide detection based on Poly-ortho-phenylenediamine modified Platinum disk microelectrode (50 μm in diameter). The electrochemical performances of H 2 O 2 detection were studied using Chronoamperometry, Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS) techniques in Phosphate Buffer Solution (PBS) pH 7.4. Effect of potential, electrode size, and various concentrations of H 2 O 2 , among others, were investigated by tracking the impedance changes at a specific perturbation frequency. To obtain the Charge transfer resistance (R ct ) values, a modified Randles Equivalent Circuit was modelled and fitted to Nyquist Plot. Then, this sensor was further applied in the detection of H 2 O 2 in antiseptic mouthwash with percent recovery of 97 % ± 0.14 (x10 3 kΩ). (author)

  7. Origin of the different behavior of some platinum decorated nanocarbons towards the electrochemical oxidation of hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Malara, A. [Dipartimento di Ingegneria dell' Informazione, delle Infrastrutture e dell' Energia Sostenibile (DIIES), Università “Mediterranea”, 89122 Reggio Calabria (Italy); Leonardi, S.G.; Bonavita, A. [Dipartimento di Ingegneria Elettronica, Chimica ed Ingegneria Industriale (DIECII), Università di Messina, 98166 Messina (Italy); Fazio, E. [Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra (MIFT), Università di Messina, 98166 Messina (Italy); Stelitano, S. [Dipartimento di Fisica (DF), Università della Calabria, 87036 Arcavacata di Rende (Italy); Neri, G. [Dipartimento di Ingegneria Elettronica, Chimica ed Ingegneria Industriale (DIECII), Università di Messina, 98166 Messina (Italy); Neri, F. [Dipartimento di Scienze Matematiche e Informatiche, Scienze Fisiche e Scienze della Terra (MIFT), Università di Messina, 98166 Messina (Italy); Santangelo, S., E-mail: saveria.santangelo@unirc.it [Dipartimento di Ingegneria Civile, dell' Energia, dell' Ambiente e dei Materiali (DICEAM), Università “Mediterranea”, 89122 Reggio Calabria (Italy)

    2016-12-01

    The electrochemical behavior of different platinum-decorated nanocarbons (Pt@C) towards the oxidation of hydrogen peroxide (H{sub 2}O{sub 2}) was investigated. Three different types of nanocarbons were considered: i) carbon black, ii) dahlia-like carbon nanohorns and iii) carbon nanotubes, which included both commercial (single-wall and multi-wall) and laboratory prepared (multi-wall) samples. Shape and size distribution of the platinum nanoparticles and morphology of the nanocarbons were analyzed by transmission electron microscopy. Their nanostructure was investigated by micro-Raman spectroscopy, while elemental composition of the samples and chemical bonding states were studied by X-ray photoelectron spectroscopy. Electrochemical behavior towards H{sub 2}O{sub 2} oxidation was evaluated by means of cyclic voltammetry modifying the working screen-printed carbon electrode surface with the prepared Pt@C nanocomposites. Data obtained suggest that the size and dispersion of the Pt nanoparticles play a key role in increasing the sensitivity towards H{sub 2}O{sub 2} detection. Thanks to the presence of smaller and more dispersed platinum particles and of a greater amount of platinum hydroxide, acting as intermediary in the H{sub 2}O{sub 2} oxidation process, Pt@dahlia-like carbon nanohorns result to be the most promising platform for the development of H{sub 2}O{sub 2} electrochemical sensors. - Highlights: • Different nanocarbons are decorated with Pt nanoparticles by wet impregnation method. • Pt@C-based hybrids are tested as active materials for sensing of hydrogen peroxide. • Sensor based on Pt@dahlia-like carbon nanohorns is the most performing device. • The origin of the different electrochemical behaviour is investigated. • Pt@C sensing performances are correlated with their structural and surface properties.

  8. Origin of the different behavior of some platinum decorated nanocarbons towards the electrochemical oxidation of hydrogen peroxide

    International Nuclear Information System (INIS)

    Malara, A.; Leonardi, S.G.; Bonavita, A.; Fazio, E.; Stelitano, S.; Neri, G.; Neri, F.; Santangelo, S.

    2016-01-01

    The electrochemical behavior of different platinum-decorated nanocarbons (Pt@C) towards the oxidation of hydrogen peroxide (H_2O_2) was investigated. Three different types of nanocarbons were considered: i) carbon black, ii) dahlia-like carbon nanohorns and iii) carbon nanotubes, which included both commercial (single-wall and multi-wall) and laboratory prepared (multi-wall) samples. Shape and size distribution of the platinum nanoparticles and morphology of the nanocarbons were analyzed by transmission electron microscopy. Their nanostructure was investigated by micro-Raman spectroscopy, while elemental composition of the samples and chemical bonding states were studied by X-ray photoelectron spectroscopy. Electrochemical behavior towards H_2O_2 oxidation was evaluated by means of cyclic voltammetry modifying the working screen-printed carbon electrode surface with the prepared Pt@C nanocomposites. Data obtained suggest that the size and dispersion of the Pt nanoparticles play a key role in increasing the sensitivity towards H_2O_2 detection. Thanks to the presence of smaller and more dispersed platinum particles and of a greater amount of platinum hydroxide, acting as intermediary in the H_2O_2 oxidation process, Pt@dahlia-like carbon nanohorns result to be the most promising platform for the development of H_2O_2 electrochemical sensors. - Highlights: • Different nanocarbons are decorated with Pt nanoparticles by wet impregnation method. • Pt@C-based hybrids are tested as active materials for sensing of hydrogen peroxide. • Sensor based on Pt@dahlia-like carbon nanohorns is the most performing device. • The origin of the different electrochemical behaviour is investigated. • Pt@C sensing performances are correlated with their structural and surface properties.

  9. Microchip-based electrochemical detection using a 3-D printed wall-jet electrode device.

    Science.gov (United States)

    Munshi, Akash S; Martin, R Scott

    2016-02-07

    Three dimensional (3-D) printing technology has evolved dramatically in the last few years, offering the capability of printing objects with a variety of materials. Printing microfluidic devices using this technology offers various advantages such as ease and uniformity of fabrication, file sharing between laboratories, and increased device-to-device reproducibility. One unique aspect of this technology, when used with electrochemical detection, is the ability to produce a microfluidic device as one unit while also allowing the reuse of the device and electrode for multiple analyses. Here we present an alternate electrode configuration for microfluidic devices, a wall-jet electrode (WJE) approach, created by 3-D printing. Using microchip-based flow injection analysis, we compared the WJE design with the conventionally used thin-layer electrode (TLE) design. It was found that the optimized WJE system enhances analytical performance (as compared to the TLE design), with improvements in sensitivity and the limit of detection. Experiments were conducted using two working electrodes - 500 μm platinum and 1 mm glassy carbon. Using the 500 μm platinum electrode the calibration sensitivity was 16 times higher for the WJE device (as compared to the TLE design). In addition, use of the 1 mm glassy carbon electrode led to limit of detection of 500 nM for catechol, as compared to 6 μM for the TLE device. Finally, to demonstrate the versatility and applicability of the 3-D printed WJE approach, the device was used as an inexpensive electrochemical detector for HPLC. The number of theoretical plates was comparable to the use of commercially available UV and MS detectors, with the WJE device being inexpensive to utilize. These results show that 3-D-printing can be a powerful tool to fabricate reusable and integrated microfluidic detectors in configurations that are not easily achieved with more traditional lithographic methods.

  10. SFG experiment and ab initio study of the chemisorption of CN - on low-index platinum surfaces

    Science.gov (United States)

    Tadjeddine, M.; Flament, J.-P.; Le Rille, A.; Tadjeddine, A.

    2006-05-01

    A dual analysis is proposed in order to have a better understanding of the adsorption of the cyanide ions on a platinum electrode. The SFG (Sum Frequency Generation) spectroscopy allows the in situ vibrational study and the SFG spectra of the CN - species adsorbed on single crystal Pt electrode allow a systematic study of the low-index platinum surfaces. This experimental work is supported by ab initio calculations using density functional theory and cluster models. For each surface orientation and each geometry, a cluster model of 20-30 Pt atoms has been built in order to interpret the chemisorption of the CN - ions through four kinds of adsorption geometry: on-top or bridge site, bonding via C or N atoms. Geometries have been optimized and adsorption energies, electronic properties and vibrational frequencies have been computed. From the electronic properties, we can propose an analysis of the bonding mechanism for each studied kind of adsorption. The SFG spectra of the CN -/Pt(1 1 1) system present an unique resonance owing to the top C adsorption. It is mainly the same for the CN -/Pt(1 0 0) system. It is also the case for the SFG spectra of the CN -/Pt(1 1 0) system recorded at negative electrochemical voltage; at more positive voltage, a second resonance appears at a lower frequency, owing to the top N adsorption. Experimental and theoretical values of the C-N stretching frequencies are in excellent agreement.

  11. Vanadium oxide (VO) based low cost counter electrode in dye sensitized solar cell (DSSC) applications

    Energy Technology Data Exchange (ETDEWEB)

    Vijayakumar, P.; Pandian, Muthu Senthil; Ramasamy, P., E-mail: ramasamyp@ssn.edu.in [SSN Research Centre, SSN College of Engineering, Kalavakkam-603 110, Chennai, Tamilnadu (India)

    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.

  12. A bimetallic nanocomposite electrode for direct and rapid ...

    Indian Academy of Sciences (India)

    A new label-free electrochemical DNA biosensor is presented based on carbon paste electrode (CPE) modified with gold (Au) and platinum (Pt) nanoparticles to prepare the bimetallic nanocomposite electrode. The proposed sensor was made by immobilization of 15-mer single stranded oligonucleotide probe related to ...

  13. Two-dimensional threshold voltage model and design considerations for gate electrode work function engineered recessed channel nanoscale MOSFET: I

    International Nuclear Information System (INIS)

    Chaujar, Rishu; Kaur, Ravneet; Gupta, Mridula; Gupta, R S; Saxena, Manoj

    2009-01-01

    This paper discusses a threshold voltage model for novel device structure: gate electrode work function engineered recessed channel (GEWE-RC) nanoscale MOSFET, which combines the advantages of both RC and GEWE structures. In part I, the model accurately predicts (a) surface potential, (b) threshold voltage and (c) sub-threshold slope for single material gate recessed channel (SMG-RC) and GEWE-RC structures. Part II focuses on the development of compact analytical drain current model taking into account the transition regimes from sub-threshold to saturation. Furthermore, the drain conductance evaluation has also been obtained, reflecting relevance of the proposed device for analogue design. The analysis takes into account the effect of gate length and groove depth in order to develop a compact model suitable for device design. The analytical results predicted by the model confirm well with the simulated results. Results in part I also provide valuable design insights in the performance of nanoscale GEWE-RC MOSFET with optimum threshold voltage and negative junction depth (NJD), and hence serves as a tool to optimize important device and technological parameters for 40 nm technology

  14. Electrode structures of polymer-electrolyte fuel cells (PEFC). An electron microscopy approach to the characterization of the electrode structure of polymer electrolyte fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Scheiba, Frieder

    2009-01-28

    catalyst and catalyst support, but that it forms a complex structure consisting of fiber and film like structures in the pores of the electrode. In addition, the EF-TEM result delivered a strong indication for the infiltration of catalyst agglomerates by the polymer electrolyte. Furthermore, a new concept for the investigation of multi-component structures, consisting of the membrane, electrodes and gas di1usion layers (GDL) was developed. Thus it was possible to provide evidence for the intrusion of individual carbon fibers from the GDL into the electrode. In addition the influence of GDL structure on delamination of the electrode could be demonstrated. Another part of the work deals with the characterization of a novel platinum catalyst deposited on hydrous ruthenium oxide coated carbon nanotubes (CNT), which was developed in close cooperation with a Chinese partner at Tsinghua University (Beijing). (orig.)

  15. Study of gold-platinum and platinum-gold surface modification and its influence on hydrogen evolution and oxygen reduction

    Directory of Open Access Journals (Sweden)

    BRANIMIR N. GRGUR

    2005-02-01

    Full Text Available Surface modification of the electrodes was conducted from sulfuric acid solutions containing the corresponding metal–chloride complexes using cyclic voltammetry. Comparing the charges of the hydrogen underpotential deposition region, and the corresponding oxide reduction regions, it is concluded that a platinum overlayer on gold forms 3D islands, while gold on platinum forms 2D islands. Foreign metals present in an amount of up to one monolayer exert an influence on the change in reaction rate with respect to both hydrogen evolution (HER and oxygen reduction (ORR reactions. Aplatinum overlayer on a gold substrate increases the activity forHER and for ORR, compared with pure gold. These results can be understood in terms of a simple model, in which the change in the H and OH binding energies are directly proportional to the shift of the d-bond center of the overlayer. On the contrary, a gold layer on platinum slightly decreases the activity for both reactions compared with pure platinum.

  16. Improved open-circuit voltage in Cu(In,Ga)Se2 solar cells with high work function transparent electrodes

    International Nuclear Information System (INIS)

    Jäger, Timo; Romanyuk, Yaroslav E.; Bissig, Benjamin; Pianezzi, Fabian; Nishiwaki, Shiro; Reinhard, Patrick; Steinhauser, Jérôme; Tiwari, Ayodhya N.; Schwenk, Johannes

    2015-01-01

    Hydrogenated indium oxide (IOH) is implemented as transparent front contact in Cu(In,Ga)Se 2 (CIGS) solar cells, leading to an open circuit voltage V OC enhanced by ∼20 mV as compared to reference devices with ZnO:Al (AZO) electrodes. This effect is reproducible in a wide range of contact sheet resistances corresponding to various IOH thicknesses. We present the detailed electrical characterization of glass/Mo/CIGS/CdS/intrinsic ZnO (i-ZnO)/transparent conductive oxide (TCO) with different IOH/AZO ratios in the front TCO contact in order to identify possible reasons for the enhanced V OC . Temperature and illumination intensity-dependent current-voltage measurements indicate that the dominant recombination path does not change when AZO is replaced by IOH, and it is mainly limited to recombination in the space charge region and at the junction interface of the solar cell. The main finding is that the introduction of even a 5 nm-thin IOH layer at the i-ZnO/TCO interface already results in a step-like increase in V OC . Two possible explanations are proposed and verified by one-dimensional simulations using the SCAPS software. First, a higher work function of IOH as compared to AZO is simulated to yield an V OC increase by 21 mV. Second, a lower defect density in the i-ZnO layer as a result of the reduced sputter damage during milder sputter-deposition of IOH can also add to a maximum enhanced V OC of 25 mV. Our results demonstrate that the proper choice of the front TCO contact can reduce the parasitic recombination and boost the efficiency of CIGS cells with improved corrosion stability

  17. The effect of ammonia upon the electrocatalysis of hydrogen oxidation and oxygen reduction on polycrystalline platinum

    DEFF Research Database (Denmark)

    Verdaguer Casadevall, Arnau; Hernandez-Fernandez, Patricia; Stephens, Ifan E.L.

    2012-01-01

    The influence of ammonium ions on the catalysis of hydrogen oxidation and oxygen reduction is studied by means of rotating ring-disk electrode experiments on polycrystalline platinum in perchloric acid. While ammonium does not affect the hydrogen oxidation reaction, the oxygen reduction reaction...

  18. High platinum utilization in ultra-low Pt loaded PEM fuel cell cathodes prepared by electrospraying

    Energy Technology Data Exchange (ETDEWEB)

    Martin, S.; Garcia-Ybarra, P.L.; Castillo, J.L. [Dept. Fisica Matematica y de Fluidos, Facultad de Ciencias, UNED, Senda del Rey 9, 28040 Madrid (Spain)

    2010-10-15

    Cathode electrodes for proton exchange membrane fuel cells (PEMFCs) with ultra-low platinum loadings as low as 0.012 mg{sub Pt}cm{sup -2} have been prepared by the electrospray method. The electrosprayed layers have nanostructured fractal morphologies with dendrites formed by clusters (about 100 nm diameter) of a few single catalyst particles rendering a large exposure surface of the catalyst. Optimization of the control parameters affecting this morphology has allowed us to overcome the state of the art for efficient electrodes prepared by electrospraying. Thus, using these cathodes in membrane electrode assemblies (MEAs), a high platinum utilization in the range 8-10 kW g{sup -1} was obtained for the fuel cell operating at 40 C and atmospheric pressure. Moreover, a platinum utilization of 20 kW g{sup -1} was attained under more suitable operating conditions (70 C and 3.4 bar over-pressure). These results substantially improve the performances achieved previously with other low platinum loading electrodes prepared by electrospraying. (author)

  19. Redeposition of electrochemically dissolved platinum as nanoparticles on carbon

    DEFF Research Database (Denmark)

    Norgaard, C. F.; Stamatin, S. N.; Skou, E. M.

    2014-01-01

    communication reports a simple chemical method for reprecipitating platinum as nanoparticles of reasonable particle size on a carbon substrate without intermediary separation and handling of solid platinum salt. After electrochemical dissolution, platinum was reprecipitated using a polyol based method. Platinum...

  20. Discharge amplified photo-emission from ultra-thin films applied to tuning work function of transparent electrodes in organic opto-electronic devices

    International Nuclear Information System (INIS)

    Gentle, A.R.; Smith, G.B.; Watkins, S.E.

    2013-01-01

    A novel photoemission technique utilising localised discharge amplification of photo-yield is reported. It enables fast, accurate measurement of work function and ionisation potential for ultra-thin buffer layers vacuum deposited onto single and multilayer transparent conducting electrodes for organic solar cells and OLED's. Work function in most traditional transparent electrodes has to be raised to maximise charge transfer while high transmittance and high conductance must be retained. Results are presented for a range of metal oxide buffers, which achieve this goal. This compact photo-yield spectroscopy tool with its fast turn-around has been a valuable development aid since ionisation potential can vary significantly as deposition conditions change slightly, and as ultra-thin films grow. It has also been useful in tracking the impact of different post deposition cleaning treatments along with some storage and transport protocols, which can adversely reduce ionisation potential and hence subsequent device performance.

  1. Textured strontium titanate layers on platinum by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Blomberg, T., E-mail: tom.blomberg@asm.com [ASM Microchemistry Ltd., Vaeinoe Auerin katu 12 A, 00560 Helsinki (Finland); Anttila, J.; Haukka, S.; Tuominen, M. [ASM Microchemistry Ltd., Vaeinoe Auerin katu 12 A, 00560 Helsinki (Finland); Lukosius, M.; Wenger, Ch. [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Saukkonen, T. [Aalto University, Puumiehenkuja 3, 02150 Espoo (Finland)

    2012-08-31

    Formation of textured strontium titanate (STO) layers with large lateral grain size (0.2-1 {mu}m) and low X-ray reflectivity roughness ({approx} 1.36 nm) on Pt electrodes by industry proven atomic layer deposition (ALD) method is demonstrated. Sr(t-Bu{sub 3}Cp){sub 2}, Ti(OMe){sub 4} and O{sub 3} precursors at 250 Degree-Sign C were used to deposit Sr rich STO on Pt/Ti/SiO{sub 2}/Si Empty-Set 200 mm substrates. After crystallization post deposition annealing at 600 Degree-Sign C in air, most of the STO grains showed a preferential orientation of the {l_brace}001{r_brace} plane parallel to the substrate surface, although other orientations were also present. Cross sectional and plan view transmission electron microscopy and electron diffraction analysis revealed more than an order of magnitude larger lateral grain sizes for the STO compared to the underlying multicrystalline {l_brace}111{r_brace} oriented platinum electrode. The combination of platinum bottom electrodes with ALD STO(O{sub 3}) shows a promising path towards the formation of single oriented STO film. - Highlights: Black-Right-Pointing-Pointer Amorphous strontium titanate (STO) on platinum formed a textured film after annealing. Black-Right-Pointing-Pointer Single crystal domains in 60 nm STO film were 0.2-1 {mu}m wide. Black-Right-Pointing-Pointer Most STO grains were {l_brace}001{r_brace} oriented.

  2. Novel non-platinum metal catalyst material

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to a novel non-platinum metal catalyst material for use in low temperature fuel cells and electrolysers and to fuel cells and electrolysers comprising the novel non-platinum metal catalyst material. The present invention also relates to a novel method for synthesizing...... the novel non-platinum metal catalyst material....

  3. Low platinum catalyst and method of preparation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Di-Jia; Chong, Lina

    2017-11-21

    A low platinum catalyst and method for making same. The catalyst comprises platinum-transition metal bimetallic alloy microcrystallites over a transition metal-nitrogen-carbon composite. A method of making a catalyst comprises preparation of transition metal organic frameworks, infusion of platinum, thermal treatment, and reduction to form the microcrystallites and composite.

  4. Correlação entre a estrutura atômica superficial e o processo de adsorção-dessorção reversível de hidrogênio em eletrodos monocristalinos Pt(111, Pt(100 e Pt(110 The correlation between the atomic surface structure and the reversible adsorption-desorption of hydrogen on single crystal Pt (111, Pt (100 and Pt (110 electrodes

    Directory of Open Access Journals (Sweden)

    Valderi Pacheco dos Santos

    2001-12-01

    Full Text Available Platinum is widely used as electrode in electrocatalytic processes, however the use of polycrystalline electrodes introduces a series of variables in the electrochemical system due to the aleatory contribution of all the crystallographic orientations with different surface packing of atoms. Single crystal platinum electrodes of low Miller index present surface structure of high regularity and serve as model to establish a correlation among the macroscopic and microscopic properties of the electrochemical interface. Therefore, the main aim of this work is the study of the voltammetric profiles of the reversible adsorption-desorption of hydrogen on Pt(100, Pt(110 and Pt(111, in order to correlate the electrochemical properties of each different orientation with the surface atomic structure.

  5. Recent strikes in South Africa’s platinum-group metal mines: effects upon world platinum-group metal supplies

    Science.gov (United States)

    Yager, Thomas R.; Soto-Viruet, Yadira; Barry, James J.

    2012-01-01

    The recent labor disputes over wages and working conditions that have affected South Africa’s three leading platinum-group metal (PGM) producers have affected an industry already plagued by market pressures and labor unrest and raised the specter of constraints in the world’s supply of these metals. Although low demand for these metals in 2011 and 2012 helped to offset production losses of recent years, and particularly those losses caused by the strikes in 2012, a prolonged resumption of strikes could cause severe shortages of iridium, platinum, rhodium, ruthenium, and, to a lesser extent, palladium.

  6. Direct alcohol fuel cells: Increasing platinum performance by modification with sp-group metals

    Science.gov (United States)

    Figueiredo, Marta C.; Sorsa, Olli; Doan, Nguyet; Pohjalainen, Elina; Hildebrand, Helga; Schmuki, Patrik; Wilson, Benjamin P.; Kallio, Tanja

    2015-02-01

    By using sp group metals as modifiers, the catalytic properties of Pt can be improved toward alcohols oxidation. In this work we report the performance increase of direct alcohol fuel cells (DAFC) fuelled with ethanol or 2-propanol with platinum based anode electrodes modified with Bi and Sb adatoms. For example, by simply adding Sb to the Pt/C based anode ink during membrane electrode assembly fabrication of a direct ethanol fuel cell (DEFC) its performance is improved three-fold, with more than 100 mV increase in the open circuit potential. For the fuel cell fuelled with 2-propanol high power densities are obtained at very high potentials with these catalyst materials suggesting a great improvement for practical applications. Particularly in the case of Pt/C-Bi, the improvement is such that within 0.6 V (from 0.7 to 0.1 V) the power densities are between 7 and 9 mW/cm2. The results obtained with these catalysts are in the same range as those obtained with other bimetallic catalysts comprising of PtRu and PtSn, which are currently considered to be the best for these type of fuel cells and that are obtained by more complicated (and consequently more expensive) methods.

  7. A Single Platinum Microelectrode for Identifying Soft Drink Samples

    Directory of Open Access Journals (Sweden)

    Lígia Bueno

    2012-01-01

    Full Text Available Cyclic voltammograms recorded with a single platinum microelectrode were used along with a non-supervised pattern recognition, namely, Principal Component Analysis, to conduct a qualitative analysis of sixteen different brands of carbonated soft drinks (Kuat, Soda Antarctica, H2OH!, Sprite 2.0, Guarana Antarctica, Guarana Antarctica Zero, Coca-Cola, Coca-Cola Zero, Coca-Cola Plus, Pepsi, Pepsi Light, Pepsi Twist, Pepsi Twist Light, Pepsi Twist 3, Schin Cola, and Classic Dillar’s. In this analysis, soft drink samples were not subjected to pre-treatment. Good differentiation among all the analysed soft drinks was achieved using the voltammetric data. An analysis of the loading plots shows that the potentials of −0.65 V, −0.4 V, 0.4 V, and 0.750 V facilitated the discrimination process. The electrochemical processes related to this potential are the reduction of hydrogen ions and inhibition of the platinum oxidation by the caffeine adsorption on the electrode surface. Additionally, the single platinum microelectrode was useful for the quality control of the soft drink samples, as it helped to identify the time at which the beverage was opened.

  8. Bifunctional electrodes for unitised regenerative fuel cells

    International Nuclear Information System (INIS)

    Altmann, Sebastian; Kaz, Till; Friedrich, Kaspar Andreas

    2011-01-01

    Research highlights: → Different oxygen electrode configurations for the operation in a unitised reversible fuel cell were tested. → Polarisation curves and EIS measurements were recorded. → The mixture of catalysts performs best for the present stage of electrode development. → Potential improvements for the different compositions are discussed. - Abstract: The effects of different configurations and compositions of platinum and iridium oxide electrodes for the oxygen reaction of unitised regenerative fuel cells (URFC) are reported. Bifunctional oxygen electrodes are important for URFC development because favourable properties for the fuel cell and the electrolysis modes must be combined into a single electrode. The bifunctional electrodes were studied under different combinations of catalyst mixtures, multilayer arrangements and segmented configurations with single catalyst areas. Distinct electrochemical behaviour was observed for both modes and can be explained on the basis of impedance spectroscopy. The mixture of both catalysts performs best for the present stage of electrode development. Also, the multilayer electrodes yielded good results with the potential for optimisation. The influence of ionic and electronic resistances on the relative performance is demonstrated. However, penalties due to cross currents in the heterogeneous electrodes were identified and explained by comparing the performance curves with electrodes composed of a single catalyst. Potential improvements for the different compositions are discussed.

  9. The iodine/iodide redox couple at a platinum electrode

    NARCIS (Netherlands)

    Dane, L.M.; Janssen, L.J.J.; Hoogland, J.G.

    1968-01-01

    The I/iodide redox couple was studied on Pt in 0.5M H2SO4 by measuring the impedance as a function of frequency. From these measurements, the exchange c.d. j0 was derived according to Sluyters. The dependence of j0 on the reversible potential and the I and the iodide concns. was established. By

  10. Comparing two methods to record maximal voluntary contractions and different electrode positions in recordings of forearm extensor muscle activity: Refining risk assessments for work-related wrist disorders.

    Science.gov (United States)

    Dahlqvist, Camilla; Nordander, Catarina; Granqvist, Lothy; Forsman, Mikael; Hansson, Gert-Åke

    2018-01-01

    Wrist disorders are common in force demanding industrial repetitive work. Visual assessment of force demands have a low reliability, instead surface electromyography (EMG) may be used as part of a risk assessment for work-related wrist disorders. For normalization of EMG recordings, a power grip (hand grip) is often used as maximal voluntary contraction (MVC) of the forearm extensor muscles. However, the test-retest reproducibility is poor and EMG amplitudes exceeding 100% have occasionally been recorded during work. An alternative MVC is resisted wrist extension, which may be more reliable. To compare hand grip and resisted wrist extension MVCs, in terms of amplitude and reproducibility, and to examine the effect of electrode positioning. Twelve subjects participated. EMG from right forearm extensors, from four electrode pairs, was recorded during MVCs, on three separate occasions. The group mean EMG amplitudes for resisted wrist extension were 1.2-1.7 times greater than those for hand grip. Resisted wrist extension showed better reproducibility than hand grip. The results indicate that the use of resisted wrist extension is a more accurate measurement of maximal effort of wrist extensor contractions than using hand grip and should increase the precision in EMG recordings from forearm extensor muscles, which in turn will increase the quality of risk assessments that are based on these.

  11. High performance electrodes for low pressure H{sub 2}-air PEM fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Besse, S; Bronoel, G; Fauvarque, J F [Laboratoires SORAPEC (France)

    1998-12-31

    Proton exchange membrane fuel cells (PEMFCs) were first developed for space applications in the 1960s. Currently, they are being manufactured for terrestrial portable power applications. One of the challenges is to develop a low pressure H{sub 2}/Air PEMFC in order to minimize the cathodic mass transport overpotentials. The hydrogen oxidation reaction is considered to be sufficiently rapid. Hydrogen transport limitations are very low even at high current densities. The different applications considered for hydrogen/air PEMFC need to work at atmospheric pressure. An optimization of the structure of the oxygen electrode and the membrane electrode assembly (MEA) are essential in order to decrease mass transport limitations and to obtain good water management even at low pressures. Efforts have been made to produce electrodes and MEA for PEMFC with low platinum loading. The electrode structure was developed to ensure a good diffusion of reactants and an effective charge collection. It has also been optimized for low pressure restrictions. It was concluded that high performances can be achieved even at low pressures by improving the electrode gas diffusion layer (PTFE content) and by improving the catalyst. 12 refs., 7 figs.

  12. Highly sensitive room temperature ammonia gas sensor based on Ir-doped Pt porous ceramic electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wenlong [College of pharmacy and biological engineering, Chengdu University, Chengdu, 610106 (China); Department of chemical and materials engineering, National Chin-Yi University of Technology, Taichung 411, Taiwan (China); Liu, Yen-Yu [Department of chemical and materials engineering, Tunghai University, Taichung 407, Taiwan (China); Do, Jing-Shan, E-mail: jsdo@ncut.edu.tw [Department of chemical and materials engineering, National Chin-Yi University of Technology, Taichung 411, Taiwan (China); Li, Jing, E-mail: lijing@cdu.edu.cn [College of pharmacy and biological engineering, Chengdu University, Chengdu, 610106 (China)

    2016-12-30

    Highlights: • Water vapors seem to hugely improve the electrochemical activity of the Pt and Pt-Ir porous ceramic electrodes. • The gas sensors based on the Pt and Pt-Ir alloy electrodes possess good sensing performances. • The reaction path of the ammonia on platinum has been discussed. - Abstract: Room temperature NH{sub 3} gas sensors based on Pt and Pt-Ir (Ir doping Pt) porous ceramic electrodes have been fabricated by both electroplating and sputtering methods. The properties of the gaseous ammonia sensors have been examined by polarization and chronoamperometry techniques. The influence of humidity on the features of the resulting sensors in the system has also been discussed, and the working potential was optimized. Water vapors seem to hugely improve the electrochemical activity of the electrode. With increasing the relative humidity, the response of the Pt-Ir(E)/Pt(S)/PCP sensor to NH{sub 3} gas could be enhanced remarkably, and the sensitivity increases from 1.14 to 12.06 μA ppm{sup −1} cm{sup −2} .Then we have also discussed the sensing mechanism of the Pt-Ir sensor and the result has been confirmed by X-ray photoelectron spectroscopy of the electrode surface before and after reaction in the end.

  13. Phospholipid monolayer coated microfabricated electrodes to model the interaction of molecules with biomembranes

    Energy Technology Data Exchange (ETDEWEB)

    Coldrick, Zachary [Centre for Self-Organising Molecular Systems (SOMS), School of Chemistry, University of Leeds, Leeds, LS2 9JT (United Kingdom)], E-mail: eenzc@leeds.ac.uk; Steenson, Paul [School of Electronic Engineering, University of Leeds, Leeds, LS2 9JT (United Kingdom); Millner, Paul [Institute of Membrane and Systems Biology, University of Leeds, Leeds, LS2 9JT (United Kingdom); Davies, Matthew [Health and Safety Laboratories, Buxton, SK17 9JN (United Kingdom); Nelson, Andrew [Centre for Self-Organising Molecular Systems (SOMS), School of Chemistry, University of Leeds, Leeds, LS2 9JT (United Kingdom)

    2009-09-01

    The hanging mercury (Hg) drop electrode (HMDE) has a classical application as a tool to study adsorption and desorption processes of surface organic films due to its: (a) atomically smooth surface and, (b) hydrophobicity at its potential of zero charge. In this study we report on a replacement of the HMDE for studying supported organic layers in the form of platinum (Pt) working electrodes fabricated using lithography techniques on which a thin film of Hg is electrodeposited. These wafer-based Pt/Hg electrodes are characterised and compared to the HMDE using rapid cyclic voltammetry (RCV) and show similar capacitance-potential profiles while being far more mechanically stable and consuming considerably less Hg over their lifetime of several months. The electrodes have been used to support self-assembled phospholipid monolayers which are dynamic surface coatings with unique dielectric properties. The issue of surface contamination has been solved by regenerating the electrode surface prior to phospholipid coating by application of extreme cathodic potentials more negative than -2.6 V (vs. Ag/AgCl). The phospholipid coated electrodes presented in this paper mimic one half of a phospholipid bilayer and exhibit interactions with the biomembrane active drug molecules chlorpromazine, and quinidine. The magnitudes of these interactions have been assessed by recording changes in the capacitance-potential profiles in real time using RCV at 40 V s{sup -1} over potential ranges >1 V. A method for electrode coating with phospholipids with the electrodes fitted in a flow cell device has been developed. This has enabled sequential rapid cleaning/coating/interaction cycles for the purposes of drug screening and/or on-line monitoring for molecules of interest.

  14. Phospholipid monolayer coated microfabricated electrodes to model the interaction of molecules with biomembranes

    International Nuclear Information System (INIS)

    Coldrick, Zachary; Steenson, Paul; Millner, Paul; Davies, Matthew; Nelson, Andrew

    2009-01-01

    The hanging mercury (Hg) drop electrode (HMDE) has a classical application as a tool to study adsorption and desorption processes of surface organic films due to its: (a) atomically smooth surface and, (b) hydrophobicity at its potential of zero charge. In this study we report on a replacement of the HMDE for studying supported organic layers in the form of platinum (Pt) working electrodes fabricated using lithography techniques on which a thin film of Hg is electrodeposited. These wafer-based Pt/Hg electrodes are characterised and compared to the HMDE using rapid cyclic voltammetry (RCV) and show similar capacitance-potential profiles while being far more mechanically stable and consuming considerably less Hg over their lifetime of several months. The electrodes have been used to support self-assembled phospholipid monolayers which are dynamic surface coatings with unique dielectric properties. The issue of surface contamination has been solved by regenerating the electrode surface prior to phospholipid coating by application of extreme cathodic potentials more negative than -2.6 V (vs. Ag/AgCl). The phospholipid coated electrodes presented in this paper mimic one half of a phospholipid bilayer and exhibit interactions with the biomembrane active drug molecules chlorpromazine, and quinidine. The magnitudes of these interactions have been assessed by recording changes in the capacitance-potential profiles in real time using RCV at 40 V s -1 over potential ranges >1 V. A method for electrode coating with phospholipids with the electrodes fitted in a flow cell device has been developed. This has enabled sequential rapid cleaning/coating/interaction cycles for the purposes of drug screening and/or on-line monitoring for molecules of interest.

  15. Nano carbon supported platinum catalyst interaction behavior with perfluorosulfonic acid ionomer and their interface structures

    DEFF Research Database (Denmark)

    Andersen, Shuang Ma

    2016-01-01

    behavior of Nafion ionomer on platinized carbon nano fibers (CNFs), carbon nano tubes (CNTs) and amorphous carbon (Vulcan). The interaction is affected by the catalyst surface oxygen groups as well as porosity. Comparisons between the carbon supports and platinized equivalents are carried out. It reveals......The interaction between perfluorosulfonic acid ionomer and supported platinum catalyst is essential. It directly influences platinum accessibility, stability of carbon support and platinum, proton conductivity and electron conductivity in an electrode. In this study, we compare the adsorption...... that the platinization step modifies the surface nature of the carbon supports in terms of specific surface area, crystallinity and especially porosity; therefore, ionomer adsorption over carbon is not always representative for the ionomer adsorption over carbon supported catalyst, though indicative. Moreover...

  16. Carbon nanotube/platinum nanoparticle nanocomposites: preparation, characterization and application in electro oxidation of alcohols

    International Nuclear Information System (INIS)

    Kalinke, Adir H.; Zarbin, Aldo J. G.

    2014-01-01

    The synthesis and characterization of different platinum nanoparticle/ carbon nanotube nanocomposite samples are described along with the application of these nanocomposites as electrocatalysts for alcohol oxidation. Samples were prepared by a biphasic system in which platinum nanoparticles (Pt-NPs) are synthesized in situ in contact with a carbon nanotube (CNT) dispersion. Variables including platinum precursor/CNT ratio, previous chemical treatment of carbon nanotubes, and presence or absence of a capping agent were evaluated and correlated with the characteristic of the synthesized materials. Samples were characterized by Raman spectroscopy, X-ray diffraction, thermogravimetric analysis and transmission electron microscopy. Glassy carbon electrodes were modified by the nanocomposite samples and evaluated as electrocatalysts for alcohol oxidation. Current densities of 56.1 and 79.8/104.7 mA cm -2 were determined for the oxidation of methanol and ethanol, respectively. (author)

  17. Voltametric study of formic and dihydroxy malonic acids on platinum for the definition of a process for the electrolytic destruction of carboxylic acids in radioactive aqueous effluents; Etude voltamperometrique des acides formiques et dihydroxymalonique sur platine en vue de la definition d`un procede de destruction electrolytique d`acides carboxyliques d`effluents aqueux radioactifs

    Energy Technology Data Exchange (ETDEWEB)

    Le Naour, C.

    1994-05-01

    To limit the amount of nuclear glasses generated by the treatment of the degraded solvent from the PUREX process for reprocessing of nuclear fuels, by solutions of sodium carbonate and caustic soda, it is planned to exploit the complexing power of certain carboxylic acids to return the metallic cations to the aqueous phase. The concept of this new treatment of the solvent by `substitution` reagents demands a process for the decomposition of these reagents, especially to CO{sub 2}. The investigation of the electrochemical behaviour, on platinum, of a substance selected as a model for understanding the interfacial mechanisms (HCOOH), and of dihydroxy malonic acid, revealed two distinct electro-poisoning processes: one is due to the adsorption of CO on the surface sites of platinum, and the second to the formation of a passivating layer of P{dagger}O. The application of 20 kHz ultrasonic flux in the neighbourhood of the platinum / aqueous formic acid solution interface also appears to cause a change in the superficial structure of the electrode used, in a direction that favours the decomposition of this compound. To overcome problems of poisoning of the platinum surface, aqueous solutions of formic, dihydroxy malonic and oxalic acids were electrolysed, in a cell without diaphragm, by applying voltage and current ranges, at levels adapted to each of the species. It is necessary to bring the working electrode to a higher potential than the oxidation potential for formic acid, and to a lower potential for dihydroxy malonic and oxalic acids. The frequent modifications of the electrode potentials helped to achieve quantitative destruction of these species, to CO{sub 2} (and to water) with an electrochemical efficiency approaching 100 %. This wet oxidation process also offers the advantage of not raising the energy potential of the effluents to be treated, because it takes place in mild conditions (ambient temperature and pressure). (author). 131 refs., 90 figs., 48 tabs.

  18. Platinum catalysts recovery of the proton exchange membrane fuel cell; Recuperacao de catalisadores de platina da celula a combustibel de membrana polimerica trocadora de protons

    Energy Technology Data Exchange (ETDEWEB)

    Fukurozaki, S.H.; Seo, E.S.M. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Ciencia e Tecnologia de Materiais. Lab. de Processamento de Residuos

    2006-07-01

    Currently, platinum is the most feasible catalyst for the Proton Exchange Membrane Fuel Cells - PEMFC. Along with platinum's significant importance in this energy system are the high cost of this noble metal and its detrimental effects on the environment. Therefore, recycling this material seems as an alternative to decrease its impacts on the environment and, at the same time, to provide a reduction of the system's costs. A search was conducted for literature and studies about platinum recycling methods. However, only two techniques of platinum recovery, which are still in development, were found. In face of this situation, a recovery method of platinum from deactivated Membrane Electrode Assembly - MEA's was developed, with attention to aspects related to the environment and the necessary requirements for its primary recycling. The results found showed a high recovery ratio and a possibility to reintroduce this metal into the production cycle. (author)

  19. Effect of multi-layered bottom electrodes on the orientation of strontium-doped lead zirconate titanate thin films

    Energy Technology Data Exchange (ETDEWEB)

    Bhaskaran, M. [Microelectronics and Materials Technology Centre, School of Electrical and Computer Engineering, RMIT University, GPO Box 2476V, Melbourne, Victoria 3001 (Australia)], E-mail: madhu.bhaskaran@gmail.com; Sriram, S. [Microelectronics and Materials Technology Centre, School of Electrical and Computer Engineering, RMIT University, GPO Box 2476V, Melbourne, Victoria 3001 (Australia); Mitchell, D.R.G.; Short, K.T. [Institute of Materials Engineering, Australian Nuclear Science and Technology Organisation (ANSTO), PMB 1, Menai, New South Wales 2234 (Australia); Holland, A.S. [Microelectronics and Materials Technology Centre, School of Electrical and Computer Engineering, RMIT University, GPO Box 2476V, Melbourne, Victoria 3001 (Australia)

    2008-09-30

    This article discusses the results from X-ray diffraction (XRD) analysis of piezoelectric strontium-doped lead zirconate titanate (PSZT) thin films deposited on multi-layer coatings on silicon. The films were deposited by RF magnetron sputtering on a metal coated substrate. The aim was to exploit the pronounced piezoelectric effect that is theoretically expected normal to the substrate. This work highlighted the influence that the bottom electrode architecture exerts on the final crystalline orientation of the deposited thin films. A number of bottom electrode architectures were used, with the uppermost metal layer on which PSZT was deposited being gold or platinum. The XRD analysis revealed that the unit cell of the PSZT thin films deposited on gold and on platinum were deformed, relative to expected unit cell dimensions. Experimental results have been used to estimate the unit cell parameters. The XRD results were then indexed based on these unit cell parameters. The choice and the thickness of the intermediate adhesion layers influenced the relative intensity, and in some cases, the presence of perovskite peaks. In some cases, undesirable reactions between the bottom electrode layers were observed, and layer architectures to overcome these reactions are also discussed.

  20. Structural property of platinum mononitride

    International Nuclear Information System (INIS)

    Yu, L.H.; Yao, K.L.; Liu, Z.L.; Zhang, Y.S.

    2007-01-01

    The structural stability and pressure-induced structural phase transition of platinum mononitride (PtN), as well as its electronic structure, were studied using the full potential augmented plane wave plus local orbitals method with the generalized gradient approximation (GGA) exchange-correlation functional. The total energy calculations show that the optimized wurtzite structure is most stable energetically among four structures: zinc blende, rocksalt, CsCl and wurtzite, which reveals the platinum mononitride PtN perhaps crystallizes in the wurtzite structure; the pressure of phase transition from wurtzite to rocksalt is predicted to be 41.4 GPa.The calculated bulk modulus of the wurtzite structure is 99.41 GPa, which is smaller than that of the other three structures and face-centered cubic Pt. The band structure calculations show wurtzite PtN is metallic

  1. Durability of Low Platinum Fuel Cells Operating at High Power Density

    Energy Technology Data Exchange (ETDEWEB)

    Polevaya, Olga [Nuvera Fuel Cells Inc.; Blanchet, Scott [Nuvera Fuel Cells Inc.; Ahluwalia, Rajesh [Argonne National Lab; Borup, Rod [Los-Alamos National Lab; Mukundan, Rangachary [Los-Alamos National Lab

    2014-03-19

    Understanding and improving the durability of cost-competitive fuel cell stacks is imperative to successful deployment of the technology. Stacks will need to operate well beyond today’s state-of-the-art rated power density with very low platinum loading in order to achieve the cost targets set forth by DOE ($15/kW) and ultimately be competitive with incumbent technologies. An accelerated cost-reduction path presented by Nuvera focused on substantially increasing power density to address non-PGM material costs as well as platinum. The study developed a practical understanding of the degradation mechanisms impacting durability of fuel cells with low platinum loading (≤0.2mg/cm2) operating at high power density (≥1.0W/cm2) and worked out approaches for improving the durability of low-loaded, high-power stack designs. Of specific interest is the impact of combining low platinum loading with high power density operation, as this offers the best chance of achieving long-term cost targets. A design-of-experiments approach was utilized to reveal and quantify the sensitivity of durability-critical material properties to high current density at two levels of platinum loading (the more conventional 0.45 mgPt.cm–1 and the much lower 0.2 mgPt.cm–2) across several cell architectures. We studied the relevance of selected component accelerated stress tests (AST) to fuel cell operation in power producing mode. New stress tests (NST) were designed to investigate the sensitivity to the addition of electrical current on the ASTs, along with combined humidity and load cycles and, eventually, relate to the combined city/highway drive cycle. Changes in the cathode electrochemical surface area (ECSA) and average oxygen partial pressure on the catalyst layer with aging under AST and NST protocols were compared based on the number of completed cycles. Studies showed elevated sensitivity of Pt growth to the potential limits and the initial particle size distribution. The ECSA loss

  2. Radiation and platinum drug interaction

    International Nuclear Information System (INIS)

    Nias, A.H.W.

    1985-01-01

    The ideal platinum drug-radiation interaction would achieve radiosensitization of hypoxic tumour cells with the use of a dose of drug which is completely non-toxic to normal tissues. Electron-affinic agents are employed with this aim, but the commoner platinum drugs are only weakly electron-affinic. They do have a quasi-alkylating action however, and this DNA targeting may account for the radiosensitizing effect which occurs with both pre- and post-radiation treatments. Because toxic drug dosage is usually required for this, the evidence of the biological responses to the drug and to the radiation, as well as to the combination, requires critical analysis before any claim of true enhancement, rather than simple additivity, can be accepted. The amount of enhancement will vary with both the platinum drug dose and the time interval between drug administration and radiation. Clinical schedules may produce an increase in tumour response and/or morbidity, depending upon such dose and time relationships. (author)

  3. Experimental and Theoretical Studies of Nanostructured Electrodes for Use in Dye-Sensitized Solar Cells

    Science.gov (United States)

    Gong, Jiawei

    Among various photovoltaic technologies available in the emerging market, dye-sensitized solar cells (DSSCs) are deemed as an effective, competitive solution to the increasing demand for high-efficiency PV devices. To move towards full commercialization, challenges remain in further improvement of device stability as well as reduction of material and manufacturing costs. This study aims at rational synthesis and photovoltaic characterization of two nanostructured electrode materials (i.e. SnO2 nanofibers and activated graphene nanoplatelets) for use as photoanode and counter electrode in dye-sensitized solar cells. The main objective is to explore the favorable charge transport features of SnO2 nanofiber network and simultaneously replace the high-priced conventional electrocatalytic nanomaterials (e.g. Pt nanoparticles) used in existing counter electrode of DSSCs. To achieve this objective, a multiphysics model of electrode kinetics was developed to optimize various design parameters and cell configurations. The porous hollow SnO2 nanofibers were successfully synthesized via a facile route consisting of electrospinning precursor polymer nanofibers, followed by controlled carbonization. The novel SnO2/TiO2 composite photoanode materials carry advantages of SnO2 nanofiber network (e.g. nanostructural continuity, high electron mobility) and TiO2 nanoparticles (e.g. high specific area), and therefore show excellent photovoltaic properties including improved short-circuit current and fill factors. In addition, hydrothermally activated graphene nanoplatelets (aGNP) were used as a catalytic counter electrode material to substitute for conventionally used platinum nanoparticles. Improved catalytic performance of aGNP electrode was achieved through increased surface area and better control of morphology. Dye-sensitized solar cells using these aGNP electrodes had power conversion efficiencies comparable to those using platinum nanoparticles with I-/I3- redox mediators

  4. Electrodes for bio-application: recording and stimulation

    International Nuclear Information System (INIS)

    Fontes, M B A

    2013-01-01

    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.

  5. Copper-based electrochemical sensor with palladium electrode for cathodic stripping voltammetry of manganese.

    Science.gov (United States)

    Kang, Wenjing; Pei, Xing; Bange, Adam; Haynes, Erin N; Heineman, William R; Papautsky, Ian

    2014-12-16

    In this work, we report on the development of a palladium-based, microfabricated point-of-care electrochemical sensor for the determination of manganese using square wave cathodic stripping voltammetry. Heavy metals require careful monitoring, yet current methods are too complex for a point-of-care system. Voltammetry offers an attractive approach to metal detection on the microscale, but traditional carbon, gold, or platinum electrodes are difficult or expensive to microfabricate, preventing widespread use. Our sensor uses palladium working and auxiliary electrodes and integrates them with a copper-based reference electrode for simple fabrication and compatibility with microfabrication and printed circuit board processing, while maintaining competitive performance in electrochemical detection. Copper electrodes were prepared on glass substrate using a combination of microfabrication procedures followed by electrodeposition of palladium. The disposable sensor system was formed by bonding a poly(dimethylsiloxane) (PDMS) well to the glass substrate. Cathodic stripping voltammetry of manganese using our new disposable palladium-based sensors exhibited 334 nM (18.3 ppb) limit of detection in borate buffer. The sensor was used to demonstrate manganese determination in natural water samples from a pond in Burnet Woods, located in Cincinnati, OH, and the Ohio River.

  6. Development and electrochemistry of a novel Ag/AgCl reference electrode suitable for mixed chloride-fluoride melts

    International Nuclear Information System (INIS)

    Pal, Rahul; Ananthasivan, K.; Anthonysamy, S.; Ganesan, V.

    2011-01-01

    Research highlights: → An Ag/AgCl reference electrode for mixed chloride-fluoride melts was developed. → Non-polarizability, reversibility and stability of the electrode were tested. → Dependence of emf vs T for Fe/Fe 2+ and Ni/Ni 2+ couples in KCl-KF melt was reported. - Abstract: Accurate values of electrode potentials are useful in understanding the electrodeposition of boron from a melt containing fluoride, chloride and fluoroborate, as well as in the determination of the thermodynamic properties of this system. A suitable reference electrode for use with this molten mixture is essential for the determination of these potentials. An Ag/AgCl reference electrode was fabricated for this purpose and its stability, reversibility and polarizability in a melt containing chloride and fluoride were studied in the temperature range 1073-1123 K. Cyclic-voltammograms (CVs) of this melt on a platinum working electrode were recorded at regular intervals over a period of 12 h. These CVs did not show any appreciable variation with time, indicating the stability of this reference electrode. The reversibility of this reference electrode was established by carrying out a micropolarization test. Cathodic and anodic polarization tests were carried out by passing a current of 1 mA and 5 mA through the cell for a duration of 300 s. After these polarization tests, the electrode swung back to its equilibrium potential within about 250 s. Reduction potentials of Fe 2+ /Fe and Ni 2+ /Ni couples in the KF-KCl melt were measured for the first time.

  7. Material and Energy Flows Associated with Select Metals in GREET 2. Molybdenum, Platinum, Zinc, Nickel, Silicon

    Energy Technology Data Exchange (ETDEWEB)

    Benavides, Pahola T. [Argonne National Lab. (ANL), Argonne, IL (United States); Dai, Qiang [Argonne National Lab. (ANL), Argonne, IL (United States); Sullivan, John L. [Argonne National Lab. (ANL), Argonne, IL (United States); Kelly, Jarod C. [Argonne National Lab. (ANL), Argonne, IL (United States); Dunn, Jennifer B. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2015-09-01

    In this work, we analyzed the material and energy consumption from mining to production of molybdenum, platinum, zinc, and nickel. We also analyzed the production of solar- and semiconductor-grade silicon. We described new additions to and expansions of the data in GREET 2. In some cases, we used operating permits and sustainability reports to estimate the material and energy flows for molybdenum, platinum, and nickel, while for zinc and silicon we relied on information provided in the literature.

  8. The influence of platinum washing-out time on its recovery from used auto catalytic converters

    Directory of Open Access Journals (Sweden)

    A. Fornalczyk

    2014-07-01

    Full Text Available The used catalytic converters contain small amounts of precious metals. Recovery of these metals is essential for environmental and economic reasons. This work presents a method of Platinum Group Metals (PGM recovery from auto catalytic converters in which they are washed out by a liquid metal. The magneto-hydro-dynamic pump was used to force circulation of liquid metal under the influence of electromagnetic fields The influence of process time on platinum recovery was also carried out.

  9. Multistage electrodeposition of supported platinum-based nanostructured systems for electrocatalytic applications

    CSIR Research Space (South Africa)

    Mkwizu, TS

    2011-05-01

    Full Text Available .R. Modibedi and Mkhulu K. Mathe* *kmathe@csir.co.za 219th ECS Meeting, 1 ? 6 May, 2011, Montreal, Canada Multistage Electrodeposition of Supported Platinum-based Nanostructured Systems for Electrocatalytic Applications Overview ? Acknowledgements... of constituent elements of the given electrode surface. ? Applications areas: Fuel cells, electrochemical sensors, electrolyzers Introduction e- A B 5 Introduction Atomic-level processes during electrocatalysis www...

  10. Nanoporous sputtered platinum-iridium-thinfilms for medical and energy applications; Nanoporoese gesputterte Platin-Iridium-Schichten fuer Anwendungen in der Medizin- und Energietechnik

    Energy Technology Data Exchange (ETDEWEB)

    Ganske, Gerald

    2012-10-05

    Sputtering makes it possible to create thinfilms of only a few atom layers and to customize them for special applications by adjusting the deposition parameters. In this work interface-layers are deposited and characterized in biological systems as stimulation electrodes for neural cells and as catalysts in hydrogen fuel cells. First of all, highly porous platinum films were created by sputtering at a pressure of 9 Pa and low power of less than 100 W. These parameters are an ideal compromise between deposition rate, porosity and disordered crystal structure of the layers. Investigations on co-sputtered platinum-iridium-films (PtIr) showed that these films form homogeneous structures and no distinction between the separate layers is possible. It was demonstrated that these films obtain the crystal structure of Pt as well as the finer cauliflower-like structure of iridium, if the atoms reach the substrate surface only with their thermal energy. Furthermore, it was shown that the film composition reflects the sputtering power of the separate targets in a linear way. The structure of the films can be predicted by means of monte-carlo-simulation, which was verified by SEM-pictures. The ratio of the sputtering power can be used to control the amount of interface elements which was confirmed by electrochemical tests. Electrode materials for the stimulation of neural cells need a large electrochemically active surface that allows for an interface between electron and ion conductivity. Test on platinum, iridium and PtIr have shown that the films sputtered at the lowest impact energy do have the largest active surface as well as the largest charge delivery capacity (CDC). Iridium films show the highest CDC (48 mC/cm{sup 2}), followed by platinum-iridium (2 mC/cm{sup 2}, 100 W power at both targets) and pure platinum (16 mC/cm{sup 2}). This can be explained by the large surface area of iridium and its electrochemical activation process. Although PtIr layers also show an

  11. Gas diffusion electrodes for PEM-fuel cells via in situ-electrodeposition; Gasdiffusionselektroden fuer PEM-Brennstoffzellen durch in situ-Elektrodeposition

    Energy Technology Data Exchange (ETDEWEB)

    Keller, Vivien

    2009-03-16

    Commercial available membrane electrode assemblies are still very expensive, since a high noble metal catalyst loading has to be on the gas diffusion electrodes. The reason is particularly the fact that a high amount of the catalyst particles is not located in the so called three phase zone between ion conducting, electron conducting and reactant phase. In the present work the electrochemical synthesis of catalyst layers with a higher catalyst utilization, i. e. with a higher amount of particles located in the three phase zone has succeeded. Thus gas diffusion electrodes comparable in performance with commercial materials but coated with a lower catalyst loading were obtained. A second objective in this work was the development of an electrocombinatoric setup in which both the combinatoric electrosynthesis as well as the combinatoric analysis of platinum and platinum alloys can be performed. Furthermore different alloys were electrodeposited and electrocombinatorically analyzed with respect to their catalytic activity in the electroreduction of oxygen and the electrooxidation of hydrogen, methanol and ethanol. (orig.)

  12. Electrochemical Preparation of Platinum Nanoparticles from Bis(acetylacetonato)platinum(II) in Some Aprotic Amide-type Ionic Liquids

    International Nuclear Information System (INIS)

    Sultana, Sharmin; Tachikawa, Naoki; Yoshii, Kazuki; Toshima, Kazunobu; Magagnin, Luca; Katayama, Yasushi

    2017-01-01

    Electrode reaction of bis(acetylacetonato)platinum(II), Pt(acac) 2 , and preparation of platinum (Pt) nanoparticles have been studied in 1-R-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (R = butyl, hexyl and decyl, which are abbreviated as BMPTFSA, HMPTFSA and DMPTFSA, respectively) ionic liquids by means of cyclic voltammetry and rotating disk electrode (RDE) method. Pt(acac) 2 was suggested to be reduced to Pt via a two-electron transfer process at a glassy carbon electrode. The diffusion coefficient of Pt(acac) 2 at 50 °C was estimated to be 1.3 × 10 −7 cm 2 s −1 in BMPTFSA, by RDE measurements. It has been demonstrated that Pt nanoparticles were able to be prepared at the glassy carbon RDE by potentiostatic electrolysis at −1.8 and −2.5 V in the ionic liquids containing Pt(acac) 2 . The prepared nanoparticles were characterized by transmission electron microscopy, energy dispersive X-ray spectroscopy and electron diffraction. No pronounced variation in the average particle sizes of Pt was observed with the rotation rates at the RDE, indicating that the average particle size was independent of the rotation rate or current density. Pt nanoparticles of average sizes of 2.1 ± 0.8, 2.8 ± 0.8 and 3.0 ± 0.8 nm were obtained after electrolysis at −1.8 V with a rotation rate of 1000 rpm in BMPTFSA, HMPTFSA and DMPTFSA, respectively, suggested that the average particle size may depend on the kind of the ionic liquid.

  13. In situ ToF-SIMS monitoring of SOFC cathodes - A case study of La0.74Sr0.17Mn1.01O2.9 model electrodes

    Science.gov (United States)

    Rohnke, M.; Schaepe, K.; Bachmann, A.-K.; Laenger, M.; Janek, J.

    2017-11-01

    The modelling of electrode kinetics of solid oxide fuel cells is challenging, as the electrodes can change their composition and microstructure during operation at high temperature. Here we present results from in situ studies, applying time of flight secondary ion mass spectrometry (ToF-SIMS) to investigate compositional surface changes of lanthanum strontium manganate (LSM) model electrodes. Geometrically well-defined LSM electrodes with the composition La0.74Sr0.17Mn1.01O2.9 were deposited as thin films on yttria stabilised zirconia (YSZ) single crystals by pulsed laser deposition. As counter electrode, a porous platinum electrode was applied on the backside of the solid electrolyte. The electrochemical polarisation experiments were carried out inside the ToF-SIMS analysis chamber at 430 °C, and the ToF-SIMS measurements were performed - in contrast to former work - for the first time during electrical polarisation at elevated temperatures. By applying either a cathodic or anodic potential to the LSM cathode, enrichment or depletion of the different metallic constituents on both, the LSM and free YSZ surface, and within the LSM near surface region, were observed. After polarisation, the system relaxes towards the thermodynamic equilibrium state. Already after the first heat treatment, diffusion of manganese and strontium from the LSM electrode onto the free YSZ surface is observed. The concomitant spreading of the three-phase boundary seems to be one reason for electrode activation after polarisation.

  14. Radiochemical neutron activation analysis of high pure palladium and platinum by ion exchange chromatography

    International Nuclear Information System (INIS)

    Sadikov, I.I.; Zinov'ev, V.G.; Sadikova, Z.O.; Salimov, M.I.

    2006-01-01

    Full text: The palladium and platinum are widely used for jewel manufacture because of their beautiful white color. However the most part of these metals are widely adopted in the world as catalysts. Many works on analytical chemistry of platinum group elements published during last years are devoted to determination of platinum and palladium in other materials. There are no articles on analysis technique of the palladium and platinum purity published during last 20 years. Available publications are very old and are published till 70th of the last century, and implement chemical and spectral methods. At the same time, the palladium and platinum are very suitable for NAA. Therefore the purpose of our research was development of high-sensitivity and multielement techniques of radiochemical neutron activation analysis of a high pure palladium and platinum. Research of nuclear characteristics of palladium and platinum has shown that radioactive nuclides with different yields are formed under the reactor neutrons. 109 , 111 , 111m Pd, 109m , 111 Ag, 191 , 197 , 199 Pt, 199 Au are the most important among them. 109Pd separation factor is equal to 1*10 5 at palladium analysis, whereas 197 Pt and 199 Au separation factor is equal to 1*10 4 at the platinum analysis every other day after irradiation. Palladium and platinum can be separated by precipitation, extraction and ion exchange methods. For separation of radioactive nuclide of the matrix elements from the impurity elements we used ion exchange chromatography system Dowex-1x8 - 1 M HNO 3 for palladium and Dowex-1x8 - 0.1 M HNO 3 for platinum. At the HNO 3 acid concentrations variation from 0,1 M to 1 M more then 25 elements have distribution factors less than 1 and 10 elements have distribution factors 5 while matrix elements have distribution factors higher than 100. It allows an effective separation of these elements from palladium and platinum. Optimum sizes of the chromatographic column and the column effluent

  15. Faradic resistance of the electrode/electrolyte interface.

    Science.gov (United States)

    Mayer, S; Geddes, L A; Bourland, J D; Ogborn, L

    1992-09-01

    A new method is used to measure the direct-current (Faradic) resistance of a single electrode/electrolyte interface. The method employs a constant-current pulse and a potential-sensing electrode. By choosing a sufficiently long pulse duration, the voltage between the test and potential-sensing electrode exhibits a three-phase response. In the steady-state phase, the voltage measured is equal to the current flowing through the electrode Faradic resistance and the resistance of the electrolyte between the test and potential-sensing electrode. By measuring this latter resistance with a high-frequency sinusoidal alternating current, the voltage drop in the electrolyte is calculated and subtracted from the voltage measured between the test and potential-sensing electrode, thereby allowing calculation of the Faradic resistance. By plotting the reciprocal of the Faradic resistance against current density and fitting the data points to a third-order polynomial, it is possible to determine the zero-current density (Faradic) resistance. This technique was used to determine the Faradic resistance of electrodes (0.1 cm2) of stainless-steel, platinum, platinum-iridium and rhodium in 0.9 per cent NaCl at 25 degrees. The zero current Faradic resistance is lowest for platinum (30.3 k omega), slightly higher for platinum-iridium (47.6k omega), much higher for rhodium (111k omega) and highest for type 316 stainless-steel (345k omega). In all cases, the Faradic resistance decreases dramatically with increasing current density.

  16. Room temperature synthesis of colloidal platinum nanoparticles

    Indian Academy of Sciences (India)

    Unknown

    platinum cation used. ... Particle size increased with low reagent concentration. ... 2,100) was added separately to the starting solution. Argon gas was bubbled in the solution for 20 min. Later, reduction of platinum ions was carried out by bubbling hydrogen gas ... plex to aquate (Cl– → H2O ligand exchange). ... copper grid.

  17. Platinum-group element mineralization

    International Nuclear Information System (INIS)

    Gruenewaldt, G.

    1985-01-01

    The purpose of this investigation is to determine the geological processes responsible for the abnormal enrichment of the platinum-group elements (PGE) in the mineralized layers of the Bushveld Complex. Questions asked are: what processes caused enrichment of the Bushveld magma in the PGE ; by what processes were these PGE concentrated in the mineralized layers ; was contamination of the Bushveld magma from external sources important in the formation of the PGE enriched layers ; what are the effects of fractional crystallization on the PGE ratios

  18. A novel temperature-gradient Na±β-alumina solid electrolyte based SOx gas sensor without gaseous reference electrode

    DEFF Research Database (Denmark)

    Rao, N.; Bleek, C.M. Van den; Schoonman, J.

    1992-01-01

    An electrochemical SOx ps sensor with a tubular Na+-beta"-alumina solid electrolyte has been fabricated and tested under non-isothermal conditions. The temperature difference between the reference and working electrode of the sensor cell is about 100-degrees-C, which causes a serious deviation...... of the experimental EMF response from the value as calculated using the Nernst equation for an isothermal system. The experimental results are Consistent with the theoretical prediction for a non-isothermal system. The response time is usually less then 10 min. SEM and EDX have been employed to investigate the sensor...... material before and after use, confirming the formation of a glassy phase of Na2SO4 by an electrochemical reaction at the interface of the platinum electrodes and Na+-beta"-alumina. According to this new theoretical derivation, the sensor design could be simplified by applying the same SO2 ps at the two...

  19. Thermoelectric energy recovery at ionic-liquid/electrode interface

    Energy Technology Data Exchange (ETDEWEB)

    Bonetti, Marco; Nakamae, Sawako; Huang, Bo Tao; Wiertel-Gasquet, Cécile; Roger, Michel [Service de Physique de l’Etat Condensé, CEA-IRAMIS-SPEC, CNRS-UMR 3680, CEA Saclay, F-91191 Gif-sur-Yvette Cedex (France); Salez, Thomas J. [Service de Physique de l’Etat Condensé, CEA-IRAMIS-SPEC, CNRS-UMR 3680, CEA Saclay, F-91191 Gif-sur-Yvette Cedex (France); École des Ponts ParisTech, 6 et 8 avenue Blaise Pascal, Champs-sur-Marne, F-77455 Marne-la-Vallée (France)

    2015-06-28

    A thermally chargeable capacitor containing a binary solution of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)-imide in acetonitrile is electrically charged by applying a temperature gradient to two ideally polarisable electrodes. The corresponding thermoelectric coefficient is −1.7 mV/K for platinum foil electrodes and −0.3 mV/K for nanoporous carbon electrodes. Stored electrical energy is extracted by discharging the capacitor through a resistor. The measured capacitance of the electrode/ionic-liquid interface is 5 μF for each platinum electrode while it becomes four orders of magnitude larger, ≈36 mF, for a single nanoporous carbon electrode. Reproducibility of the effect through repeated charging-discharging cycles under a steady-state temperature gradient demonstrates the robustness of the electrical charging process at the liquid/electrode interface. The acceleration of the charging by convective flows is also observed. This offers the possibility to convert waste-heat into electric energy without exchanging electrons between ions and electrodes, in contrast to what occurs in most thermogalvanic cells.

  20. Effect of the platinum content on the microstructure and micropore size distribution of Pt/alumina-pillared clays.

    Science.gov (United States)

    Barrera-Vargas, M; Valencia-Rios, J; Vicente, M A; Korili, S A; Gil, A

    2005-12-15

    The aim of this work is to study the effect of the platinum content (0-1.8 wt % Pt) on the microstructure of an alumina-pillared clay. For this purpose, the nitrogen physisorption data at -196 degrees C, the micropore size distributions of the supported platinum catalysts, and the hydrogen chemisorption results at 30 degrees C have been analyzed and compared. The preparation of the catalysts has modified the textural properties of the Al-pillared clay support, giving rise to a loss of surface area and micropore volume. After reduction at 420 degrees C, the presence of dispersed metallic platinum with mean crystallite size in the 22-55 A range has been found by hydrogen adsorption. Comparison of all results reveals that the platinum species block the micropore entrances by steric hindrance to nitrogen access as the platinum content increases.

  1. A novel reusable platinum nanocatalyst

    International Nuclear Information System (INIS)

    Zhou Weiqiang; Wang Jing; Wang Chuanyi; Du Yukou; Xu Jingkun; Yang Ping

    2010-01-01

    Recyclability of noble metal catalysts is a challenging issue when dealing with their industrial applications. Smart pH-sensitive Pt nanoparticles were successfully prepared for the first time by using octa(N,N-diacetic acid phenylamine)silsesquioxane (OAPAS) as a macromolecular protective agent. As-prepared Pt nanoparticles can self-aggregate or redisperse by only changing the pH of the system solution. In the weak acidic or alkaline solution (pH > 4.0), the Pt nanoparticles dispersed homogenously; while in the acidic solution (pH = 2.5), they self-aggregated. The dynamic self-aggregation and redispersion processes of the Pt nanoparticles driven by pH changes were revealed by transmission electron microscopy measurements. Electrocatalytic experiments proved that the platinum nanoparticles as a recyclable catalyst showed excellent activity for the hydrogenation of aldehyde after runs of five times. Such platinum nanoparticles are thereby anticipated to have great potential functioning as 'smart' catalysts for industrial applications.

  2. Plain to point network reduced graphene oxide - activated carbon composites decorated with platinum nanoparticles for urine glucose detection

    Science.gov (United States)

    Hossain, Mohammad Faruk; Park, Jae Y.

    2016-02-01

    In this study, a hydrothermal technique was applied to synthesize glucose-treated reduced graphene oxide-activated carbon (GRGO/AC) composites. Platinum nanoparticles (PtNP) were electrochemically deposited on the modified GRGO/AC surface, and chitosan-glucose oxidase (Chit-GOx) composites and nafion were integrated onto the modified surface of the working electrode to prepare a highly sensitive glucose sensor. The fabricated biosensor exhibited a good amperometric response to glucose in the detection range from 0.002 mM to 10 mM, with a sensitivity of 61.06 μA/mMcm2, a short response time (4 s) and a low detection limit of 2 μM (signal to noise ratio is 3). The glucose sensor exhibited a negligible response to interference and good stability. In addition, the glucose levels in human urine were tested in order to conduct a practical assessment of the proposed sensor, and the results indicate that the sensor had superior urine glucose recognition. These results thus demonstrate that the noble nano-structured electrode with a high surface area and electrocatalytic activity offers great promise for use in urine glucose sensing applications.

  3. Quantum conductance of 4,4-bipyridine molecular junctions: Role of electrode work function and local d band

    DEFF Research Database (Denmark)

    Rauba, J.M.C.; Strange, Mikkel; Thygesen, Kristian Sommer

    2008-01-01

    conductance than the Pt-BPD junction due to the smaller work function of Au as compared to Pt. On the other hand, coupling to the local d band is stronger in the case of Pt and this broadens the LUMO resonance. We find that these effects largely outbalance each other leading to conductances of 0.01G(0) and 0......-principles results within a simple single-level model....

  4. Bioethanol in Biofuels Checked by an Amperometric Organic Phase Enzyme Electrode (OPEE Working in “Substrate Antagonism” Format

    Directory of Open Access Journals (Sweden)

    Mauro Tomassetti

    2016-08-01

    Full Text Available The bioethanol content of two samples of biofuels was determined directly, after simple dilution in decane, by means of an amperometric catalase enzyme biosensor working in the organic phase, based on substrate antagonisms format. The results were good from the point of view of accuracy, and satisfactory for what concerns the recovery test by the standard addition method. Limit of detection (LOD was on the order of 2.5 × 10−5 M.

  5. Voltammetry at micro-mesh electrodes

    Directory of Open Access Journals (Sweden)

    Wadhawan Jay D.

    2003-01-01

    Full Text Available The voltammetry at three micro-mesh electrodes is explored. It is found that at sufficiently short experimental durations, the micro-mesh working electrode first behaves as an ensemble of microband electrodes, then follows the behaviour anticipated for an array of diffusion-independent micro-ring electrodes of the same perimeter as individual grid-squares within the mesh. During prolonged electrolysis, the micro-mesh electrode follows that behaviour anticipated theoretically for a cubically-packed partially-blocked electrode. Application of the micro-mesh electrode for the electrochemical determination of carbon dioxide in DMSO electrolyte solutions is further illustrated.

  6. The kinetics of porous insertion electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Atlung, S; West, K [British Columbia Univ., Vancouver (Canada)

    1989-05-01

    The principles of porous electrodes are discussed as well as the discharge of the insertion compound, the working potential, transport in the electrolyte, the time dependence of the electrolyte concentration, and modeling of the porous electrode. The simulation of a TiS2 porous electrode and the composite insertion electrode are considered as well. The influence of electrode thickness and porosity in a typical porous TiS2 electrode is revealed. It is shown that the use of insertion compounds as battery electrodes is limited by the requirement that the inserted ion must be distributed in the interior of the insertion compound particle. 15 refs.

  7. Liquid electrode

    Science.gov (United States)

    Ekechukwu, A.A.

    1994-07-05

    A dropping electrolyte electrode is described for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions. 2 figures.

  8. Platinum replica electron microscopy: Imaging the cytoskeleton globally and locally.

    Science.gov (United States)

    Svitkina, Tatyana M

    2017-05-01

    Structural studies reveal how smaller components of a system work together as a whole. However, combining high resolution of details with full coverage of the whole is challenging. In cell biology, light microscopy can image many cells in their entirety, but at a lower resolution, whereas electron microscopy affords very high resolution, but usually at the expense of the sample size and coverage. Structural analyses of the cytoskeleton are especially demanding, because cytoskeletal networks are unresolvable by light microscopy due to their density and intricacy, whereas their proper preservation is a challenge for electron microscopy. Platinum replica electron microscopy can uniquely bridge the gap between the "comfort zones" of light and electron microscopy by allowing high resolution imaging of the cytoskeleton throughout the entire cell and in many cells in the population. This review describes the principles and applications of platinum replica electron microscopy for studies of the cytoskeleton. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Recycling of platinum group metals from the automotive catalysts

    International Nuclear Information System (INIS)

    Benevit, Mariana; Petter, Patricia Melo Halmenschlager; Veit, Hugo Marcelo

    2014-01-01

    Currently it is very important to use alternative sources of raw material for obtaining metals, avoiding the traditional mining. This work aims to characterize and evaluate the recoverability of platinum group metals present in automotive catalysts. Thus, the catalysts were divided into two groups: the first was catalysts used in 1.0 cars and the second was catalyst used in 2.0 cars. DRX and FRX techniques and chemical analysis performed by ICP/OES was used to characterized these materials. The results showed that there is a significant amount of platinum group elements in catalyst waste, which can be separated and reused. In the next step, hydro and pyrometallurgical routes, for metals extraction from catalyst waste, will be studied. (author)

  10. Hierarchical electrode architectures for electrical energy storage & conversion.

    Energy Technology Data Exchange (ETDEWEB)

    Zavadil, Kevin Robert; Missert, Nancy A.; Shelnutt, John Allen; van Swol, Frank B.

    2012-01-01

    The integration and stability of electrocatalytic nanostructures, which represent one level of porosity in a hierarchical structural scheme when combined with a three-dimensional support scaffold, has been studied using a combination of synthetic processes, characterization techniques, and computational methods. Dendritic platinum nanostructures have been covalently linked to common electrode surfaces using a newly developed chemical route; a chemical route equally applicable to a range of metals, oxides, and semiconductive materials. Characterization of the resulting bound nanostructure system confirms successful binding, while electrochemistry and microscopy demonstrate the viability of these electroactive particles. Scanning tunneling microscopy has been used to image and validate the short-term stability of several electrode-bound platinum dendritic sheet structures toward Oswald ripening. Kinetic Monte Carlo methods have been applied to develop an understanding of the stability of the basic nano-scale porous platinum sheets as they transform from an initial dendrite to hole containing sheets. Alternate synthetic strategies were pursued to grow dendritic platinum structures directly onto subunits (graphitic particles) of the electrode scaffold. A two-step photocatalytic seeding process proved successful at generating desirable nano-scale porous structures. Growth in-place is an alternate strategy to the covalent linking of the electrocatalytic nanostructures.

  11. The investigation of movement dynamics of an AC electric arc attachment along the working surface of a hollow cylindrical electrode under the action of gas-dynamic and electromagnetic forces

    International Nuclear Information System (INIS)

    Surov, A V; Popov, S D; Serba, E O; Nakonechny, G V; Spodobin, V A; Ovchinnikov, R V; Kumkova, I I; Shabalin, S A

    2012-01-01

    Stationary electric arc alternating current plasma torches are used today for realization of plasma chemical technologies requiring relatively high energy input. Waste treatment is one these directions. The paper reports on experiment results directed towards the increase in the lifetime characteristics of electrode units of the powerful high-voltage electric-arc AC plasma torches. The solution to the problem of obtainment the uniform wear of a copper hollow cylindrical electrode achieved by the controlled movement of the arc attachment along the working surface was offered. Organization of gas supply in the near electrode area and application of alternating magnetic field ensured movement of arc attachment along the surface with average speed from 2 to 14 m/s. Arc current was about 47 A and 84 A, gas flow rate in near electrode area was about 5 and 4.5 g/s. Due to researches on the experimental prototype of a hollow cylindrical electrode, the erosion of its material reached only 3 μg/C, that enables production of the electrode assembly with life time above 1000 hours at currents in the arc up to 100–200 A.

  12. Glucose oxidase immobilization on different modified surfaces of platinum nanowire for application in glucose detection

    International Nuclear Information System (INIS)

    Le, Thi Thanh Tuyen; Tran, Phu Duy; Pham, Xuan Tung; Tong, Duy Hien; Dang, Mau Chien

    2010-01-01

    In this work, the surface of platinum (Pt) nanowires was modified by using several chemicals, including a compound of gelatin gel with SiO 2 , polyvinyl alcohol (PVA) with Prussian blue (PB) mediator and cysteamine self-assembled monolayers (SAM). Then, glucose oxidase (GOD) enzyme was immobilized on the modified surfaces of Pt nanowire electrodes by using techniques of electrochemical adsorption and chemical binding. The GOD immobilized Pt nanowires were used for application in glucose detection by performing a cyclic voltammetry measurement. The detection results showed that GOD was immobilized on all of the tested surfaces and the highest glucose detection sensitivity of 60 μM was obtained when the Pt nanowires were modified by PVA with PB mediator. Moreover, the sensors showed very high current response when the Pt nanowires were modified with the cysteamine SAM. The stability and catalyst activity of GOD are also reported here. For instance, the catalyst activity of GOD retained about 60% of its initial value after it was stored at 4 °C in a 100 mM PBS buffer solution with a pH of 7.2 for a period of 30 days

  13. KOH-activated multi-walled carbon nanotubes as platinum supports for oxygen reduction reaction

    Science.gov (United States)

    He, Chaoxiong; Song, Shuqin; Liu, Jinchao; Maragou, Vasiliki; Tsiakaras, Panagiotis

    In the present investigation, multi-walled carbon nanotubes (MWCNTs) thermally treated by KOH were adopted as the platinum supporting material for the oxygen reduction reaction electrocatalysts. FTIR and Raman spectra were used to investigate the surface state of MWCNTs treated by KOH at different temperatures (700, 800, and 900 °C) and showed MWCNTs can be successfully functionalized. The structural properties of KOH-activated MWCNTs supported Pt were determined by X-ray diffraction (XRD) and transmission electron microscopy (TEM), and their electrochemical performance was evaluated by the aid of cyclic voltammetry (CV) and rotating disk electrode (RDE) voltammetry. According to the experimental findings of the present work, the surrface of MWCNTs can be successfully functionalized with oxygen-containing groups after activation by KOH, favoring the good dispersion of Pt nanoparticles with narrow size distribution. The as-prepared Pt catalysts supported on KOH treated MWCNTs at higher temperature, possess higher electrochemical surface area and exhibit desirable activity towards oxygen reduction reaction (ORR). More precisely, it has been found that the electrochemical active area of Pt/MWCNTs-900 is approximately two times higher than that of Pt/MWCNTs. It can be concluded that KOH activation is an effective way to decorate MWCNTs' surface with oxygen-containing groups and bigger surface area, which makes them more suitable as electrocatalyst support materials.

  14. Electrochemical Immunoassay Using Open Circuit Potential Detection Labeled by Platinum Nanoparticles

    Directory of Open Access Journals (Sweden)

    Kanokwan Charoenkitamorn

    2018-02-01

    Full Text Available In this work, a simple electrochemical immunoassay based on platinum nanoparticles (PtNPs using open circuit potential (OCP detection was developed. The detection of human chorionic gonadotropin hormone (hCG as a model analyte, was demonstrated by direct electrical detection of PtNPs in hydrazine solution using OCP measurement without any application of either potential or current to the system. Disposable screen-printed carbon electrodes (SPCEs were utilized for the development of our immunosensor, which required a sample volume as small as 2 μL. After preparation of a sandwich-type immunosystem, hydrazine solution was dropped on the electrode’s surface, which was followed immediately by electrical detection using OCP. The change of the OCP signal originated from electrocatalytic oxidation of the hydrazine on PtNPs. Under the optimal conditions of a pH of 6.0 and a hydrazine concentration of 1 mM, a detection limit of 0.28 ng mL−1 and a linearity of 0–10 ng mL−1 were obtained. The PtNP-based OCP method is a simpler electrochemical detection procedure than those obtained from other electrochemical methods and has an acceptable sensitivity and reproducibility. The simplicity of the detection procedure and the cost-effectiveness of the disposable SPCE illustrate the attractive benefits of this sensor. Moreover, it could be applied to a simplified and miniaturized diagnostic system with minimal user manipulation.

  15. Glucose oxidase immobilization on different modified surfaces of platinum nanowire for application in glucose detection

    Science.gov (United States)

    Thanh Tuyen Le, Thi; Duy Tran, Phu; Pham, Xuan Tung; Hien Tong, Duy; Chien Dang, Mau

    2010-09-01

    In this work, the surface of platinum (Pt) nanowires was modified by using several chemicals, including a compound of gelatin gel with SiO2, polyvinyl alcohol (PVA) with Prussian blue (PB) mediator and cysteamine self-assembled monolayers (SAM). Then, glucose oxidase (GOD) enzyme was immobilized on the modified surfaces of Pt nanowire electrodes by using techniques of electrochemical adsorption and chemical binding. The GOD immobilized Pt nanowires were used for application in glucose detection by performing a cyclic voltammetry measurement. The detection results showed that GOD was immobilized on all of the tested surfaces and the highest glucose detection sensitivity of 60 μM was obtained when the Pt nanowires were modified by PVA with PB mediator. Moreover, the sensors showed very high current response when the Pt nanowires were modified with the cysteamine SAM. The stability and catalyst activity of GOD are also reported here. For instance, the catalyst activity of GOD retained about 60% of its initial value after it was stored at 4 °C in a 100 mM PBS buffer solution with a pH of 7.2 for a period of 30 days.

  16. Electrodes for the hydrogen through water electrolysis using BMI.BF{sub 4} as electrolyte; Eletrodos para a producao de hidrogenio via eletrolise da agua utilizando BMI.BF{sub 4} como eletrolito

    Energy Technology Data Exchange (ETDEWEB)

    Botton, Janine Padilha; Martini, Emilse M.A.; Souza, Michele Oberson de; Souza, Roberto Fernando de [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Inst. de Quimica. Lab. de Eletroquimica e Catalise]. E-mail: janine@iq.ufrgs.br; Loget, Gabriel [Universite de Rennes 1, Rennes (France). Lab. de Eletroquimica Molecular e Macromolecular. UMR CNRS 6510

    2008-07-01

    The hydrogen production by water electrolysis was tested with different electrocatalysts (nickel, iron alloys containing nickel, chromium and manganese, and molybdenum) in the ionic liquid electrolyte, 1-butyl-3-methylimidazolium tetrafluoroborate (BMI.BF{sub 4}), 10 vol.% in water. The hydrogen evolution reaction (HER) worked at room temperature with a platinum quasi-reference electrode (PtQRE) applying a -1.7 V potential. The experimental conditions used were determined in previous work and such parameters of operation were confirmed with the electrocatalysts employed in this work. A Hoffman cell apparatus was used to perform the water electrolysis. The current density values, j, obtained were between 3.0 mA cm{sup -2} and 77.5 mA cm{sup -2}. The system efficiency was very high for all electrocatalysts tested, between 97.0% and 99.2%. The molybdenum (Mo) electrode was better than others showing the highest current density value in HER. This behavior has been explained by the lower value of activation energy for the electrolysis reaction when Mo is employed comparing with Pt electrode. The energy activation of the HER using platinum (Pt) as electrocatalyst in an aqueous solution of BMI.BF{sub 4} 10 vol.% was 23.40 kJ mol{sup -1}, whereas with electrode of Mo in the same conditions , was 9.22 kJ mol{sup -1}. In an alkaline aqueous electrolyte (usual medium for such reaction), Mo is less efficient than Pt explaining the lack of published citation using pure Mo as cathode for the HER. The excellent results obtained with a Mo electrode employing ionic liquid as electrolyte show that the hydrogen production can be carried out with cheap electrode material at room temperature, which makes this method economically attractive. (author)

  17. electrode array

    African Journals Online (AJOL)

    PROF EKWUEME

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

  18. Platinum Group Metal Recycling Technology Development - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Lawrence Shore

    2009-08-19

    BASF Catalysts LLC, formerly Engelhard Corporation, has completed a project to recover Pt from PEM fuel cell membrane electrode assemblies. The project, which began in 2003, has met the project objective of an environmentally-friendly, cost-effective method for recovery of platinum without release of hydrogen fluoride. This has been achieved using a combination of milling, dispersion and acid leaching. 99% recovery of Pt was achieved, and this high yield can be scaled up using one vessel for a single leach and rinse. Leaching was been successfully achieved using a 10% solids level, double the original target. At this solids content, the reagent and utility costs represent ~0.35% of the Pt value of a lot, using very conservative assumptions. The main cost of the process is capital depreciation, followed by labor.

  19. The evaluation of the polarization resistance in a tubular electrode and its application to the hydrogen electrode reaction

    International Nuclear Information System (INIS)

    Montero, M.A.; Marozzi, C.A.; Chialvo, M.R. Gennero de; Chialvo, A.C.

    2007-01-01

    An alternative method for the determination of the kinetic parameters involved in the elementary steps of the reaction mechanism of the hydrogen electrode reaction is proposed. It is based on the determination of the variation of the polarization resistance in a tubular platinum electrode with a laminar flow of electrolyte as a function of the activity of protons of the electrolyte solution. A theoretical expression that relates the experimental variables and the equilibrium polarization resistance is developed, which takes into account the current distribution along the electrode surface. The results are compared with others obtained previously, contributing to the verification of the kinetic mechanism through a completely different experimental procedure

  20. Superficial characterization and zircaloy-2 electrochemistry with hydrothermal deposit of platinum; Caracterizacion superficial y electroquimica de zircaloy-2 con deposito hidrotermal de platino

    Energy Technology Data Exchange (ETDEWEB)

    Contreras R, A.; Arganis J, C. R.; Medina A, A. L. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Gris C, M. M., E-mail: aida.contreras@inin.gob.mx [Comision Federal de Electricidad, Central Nucleoelectrica Laguna Verde, Carretera Cardel-Nautla Km 42.5, Alto Lucero, Veracruz (Mexico)

    2011-11-15

    The combustible elements of the boiling water nuclear reactors (BWR) are formed by zircaloy-2 tubes that contain in their interior UO{sub 2} pellets. With the objective of mitigating the speed of crack growth by IGSCC to a minimum negative impact on the BWR operation, General Electric developed the noble metals chemical addition (NMCA), in where noble metals particles as Pt, Pd, and Rh, are deposited on the surface of the metal to catalyze the recombination of H{sub 2} and O{sub 2}. Hydrogen is also injected to have it in excess and to favor this recombination (HWC) and zinc to reduce dose. In this work was oxidized zircaloy-2 low similar conditions to the HWC, platinum was deposited starting from a solution of Na{sub 2}Pt(OH){sub 6} with 30 ppm of Pt, in refined samples and without polishing, they were characterized by scanning electron microscopy, energy dispersed spectroscopy, XPS and electrochemistry, by means of Tafel curves and cyclical polarization. On the zircaloy surface was found a ZrO{sub 2} layer that remains under the different study conditions. Under HWC conditions is the oxides formation, possibly complex oxides of zirconium, iron and tin. After the platinum deposit these oxides decrease forming the sub-oxides: Zr{sub 2}O, Zr O, Zr{sub 2}O{sub 3}. The Tafel curves indicates the reduction of the oxygen of the sample with platinum and the cyclical polarization curves show that the reactions that happen on the zircaloy electrodes are not dur to located corrosion. (Author)

  1. Mechanism of Platinum Derivatives Induced Kidney Injury

    Directory of Open Access Journals (Sweden)

    Feifei YAN

    2015-09-01

    Full Text Available Platinum derivatives are the most widely used chemotherapeutic agents to treat solid tumors including ovarian, head and neck, and testicular germ cell tumors, lung cancer, and colorectal cancer. Two major problems exist, however, in the clinic use of platinum derivatives. One is the development of tumor resistance to the drug during therapy, leading to treatment failure. The other is the drug’s toxicity such as the cisplatin’s nephrotoxicity, which limits the dose that can be administered. This paper describes the mechanism of platinum derivatives induced kidney injury.

  2. Adsorption on smooth electrodes: A radiotracer study

    International Nuclear Information System (INIS)

    Rice-Jackson, L.M.

    1990-01-01

    Adsorption on solids is a complicated process and in most cases, occurs as the early stage of other more complicated processes, i.e. chemical reactions, electrooxidation, electroreduction. The research reported here combines the electroanalytical method, cyclic voltammetry, and the use of radio-labeled isotopes, soft beta emitters, to study adsorption processes at smooth electrodes. The in-situ radiotracer method is highly anion (molecule) specific and provides information on the structure and composition of the electric double layer. The emphasis of this research was on studying adsorption processes at smooth electrodes of copper, gold, and platinum. The application of the radiotracer method to these smooth surfaces have led to direct in-situ measurements from which surface coverage was determined; anions and molecules were identified; and weak interactions of adsorbates with the surface of the electrodes were readily monitored. 179 refs

  3. Hydrogen electrode reaction: A complete kinetic description

    International Nuclear Information System (INIS)

    Quaino, P.M.; Gennero de Chialvo, M.R.; Chialvo, A.C.

    2007-01-01

    The kinetic description of the hydrogen electrode reaction (HER) in the whole range of overpotentials (-0.2 < η (V) < 0.40) is presented. The Volmer-Heyrovsky-Tafel mechanism was solved considering simultaneously the following items: (i) the diffusional contribution of the molecular hydrogen from and towards the electrode surface, (ii) the forward and backward reaction rates of each elementary step and (iii) a Frumkin type adsorption for the reaction intermediate. In order to verify the descriptive capability of the kinetic expressions derived, an experimental study of the HER was carried out on a rotating platinum disc electrode in acid solution. From the correlation of these results the elementary kinetic parameters were evaluated and several aspects related to the kinetic mechanism were discussed. Finally, the use of these kinetic expressions to interpret results obtained on microelectrodes is also analysed

  4. Adsorption and temperature-programmed desorption of hydrogen with dispersed platinum and platinum-gold catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, J.R.; Foger, K.; Breakspere, R.J.

    1979-05-01

    Adsorption and temperature-programmed desorption of hydrogen with dispersed platinum and platinum-gold catalysts was studied with 0.9-3Vertical Bar3< platinum on silica gel, aerosil, sodium and lanthanum Y zeolites, and ..gamma..-alumina, and on aerosil-supported gold-platinum alloys containing 2, 10, 24, 33, and 85Vertical Bar3< gold. Surface enrichment with gold in the alloy systems, as derived from hydrogen adsorption data and predicted from surface enrichment theory and electron microscopic measurements of particle size, were in good agreement, which indicated that equilibrium was achieved by the thermal treatment (oxygen at 573/sup 0/K, hydrogen at 620/sup 0/K, repeated cycles) used. Hydrogen spillover to gold was observed at the higher hydrogen pressures tested on the alloys with high gold content, and to the zeolite supports. The temperature-programed desorption profiles were independent of gold content, which indicated that gold acts only as diluent, and that isolated surface platinum atoms become populated with hydrogen atoms either by hydrogen atom spillover from platinum ensembles to gold and from the gold to the isolated platinum, and/or by adsorption of a molecule directly on the isolated platinum and chemisorption of one H atom at an adjacent gold atom. The distribution of surface platinum ensembles was evaluated by a computer simulation method.

  5. Hydrogenation of hexene over platinum on alumina vs. platinum in a Na-Y zeolite

    International Nuclear Information System (INIS)

    Miner, R.S. Jr.; Ione, K.G.; Namba, S.; Turkevich, J.

    1978-01-01

    In order to study the efficacy of zeolites as supports, several platinum H--Y zeolites were prepared by ion exchanging an H--Y zeolite with Pt(NH 3 ) 4 Cl 2 and reducing these products with hydrazine hydrate (A, B, C). Another preparation was made by adsorbing 32-A platinum sol on the zeolite crystallites (D). These catalysts were studied for hydrogenation and isomerization of hexene-1, ethylene hydrogenation, hydrogen chemisorption, and poison titration. They were compared with monodisperse Pt (32 A diameter) on alumina. A marked difference was found between the behavior of hexene-1 with the platinum-in-zeolite and with the platinum-on-alumina

  6. Platinum redispersion on metal oxides in low temperature fuel cells.

    Science.gov (United States)

    Tripković, Vladimir; Cerri, Isotta; Nagami, Tetsuo; Bligaard, Thomas; Rossmeisl, Jan

    2013-03-07

    We have analyzed the aptitude of several metal oxide supports (TiO(2), SnO(2), NbO(2), ZrO(2), SiO(2), Ta(2)O(5) and Nb(2)O(5)) to redisperse platinum under electrochemical conditions pertinent to the Proton Exchange Membrane Fuel Cell (PEMFC) cathode. The redispersion on oxide supports in air has been studied in detail; however, due to different operating conditions it is not straightforward to link the chemical and the electrochemical environment. The largest differences reflect in (1) the oxidation state of the surface (the oxygen species coverage), (2) temperature and (3) the possibility of platinum dissolution at high potentials and the interference of redispersion with normal working potential of the PEMFC cathode. We have calculated the PtO(x) (x = 0, 1, 2) adsorption energies on different metal oxides' surface terminations as well as inside the metal oxides' bulk, and we have concluded that NbO(2) might be a good support for platinum redispersion at PEMFC cathodes.

  7. Investigations on structural iron electrochemical properties in layered silicates using massive mica electrodes

    International Nuclear Information System (INIS)

    Hadi, J.; Ignatiadis, I.; Tournassat, C.; Charlet, L.; Silvester, E.

    2012-01-01

    Document available in extended abstract form only. Nuclear waste repositories are being installed in deep excavated rock formations in some places in Europe to isolate and store radioactive waste. In France, the Callovo-Oxfordian formation (COx) is a potential candidate for a nuclear waste repository. The redox reactivity of COx clay rock samples are already under study using microscopic, spectrometric and wet analysis techniques. In order to cross and overcome certain limits by improvement in the knowledge, specific electrodes should be constructed and devoted to the deepening of the electrochemical behaviour of the COx system in different situations. Iron is one of the most common redox species in soils and sedimentary rocks. Iron-bearing phyllosilicates play key roles in various biogeochemical processes. The complexity of the physical and chemical changes involving their structural iron makes the studies of its redox properties challenging. Most of the recent reported efforts were focused on probing Fe redox on finely powdered clay particles, and have been hampered by inadequate interactions between particles and electrodes. Moreover, such experiments usually involve redox probe ions, thus adding supplementary difficulties in the determination of structural iron redox parameters such as redox potential (Eh) and kinetics. The present study aims at qualitatively investigating the above mentioned phenomena on minerals like iron-bearing micas. In the current work, we present initial insights regarding efforts to build a direct electrical interface between solid electrodes and conveniently shaped macroscopic mica crystals in order to investigate the redox properties of structural iron in dry and aqueous environments, in the presence of representative perturbations. A classical three electrode system has been used for voltammetric measurements. Platinum plate was the counter electrode. Potentials have been measured against either silver-silver chloride electrode or

  8. VB Platinum Tile & Carpet, Inc. Information Sheet

    Science.gov (United States)

    VB Platinum Tile & Carpet, Inc. (the Company) is located in Bristow, Virginia. The settlement involves renovation activities conducted at a property constructed prior to 1978, located in Washington, DC.

  9. Platinum-Resistor Differential Temperature Sensor

    Science.gov (United States)

    Kolbly, R. B.; Britcliffe, M. J.

    1985-01-01

    Platinum resistance elements used in bridge circuit for measuring temperature difference between two flowing liquids. Temperature errors with circuit are less than 0.01 degrees C over range of 100 degrees C.

  10. Effect of glassy carbon properties on the electrochemical deposition of platinum nano-catalyst and its activity for methanol oxidation

    Directory of Open Access Journals (Sweden)

    SANJA TERZIC

    2007-02-01

    Full Text Available The effects of the properties of glassy carbon on the deposition of platinum particles and the electrocatalytic activity of platinum supported on glassy carbon (GC/Pt for methanol oxidation in alkaline and acidic solutions were studied. Platinum was potentiostatically deposited on two glassy carbon samples, thermally treated at different temperatures, which were either polished or anodicaly polarised in acid (GCOX-AC/Pt and in alkali (GCOX-AL/Pt. Anodic polarisation of glassy carbon, either in alkaline or acidic solution, enhances the activity of both types of GC/Pt electrodes for methanol oxidation. The activity of the catalysts follows the change in the properties of the glassy carbon support upon anodic treatment. The specific activity of the GCOX-AL/Pt electrode for this reaction in alkali is increased only a few times in comparison with the activity of the GC/Pt one. On the other hand, the specific activity of the GCOX-AC/Pt electrode for methanol oxidation in acid is about one order of magnitude higher than that of the GC/Pt electrode. The role of the substrate on the properties of catalyst is discussed in detail.

  11. SERS and DFT study of water on metal cathodes of silver, gold and platinum nanoparticles.

    Science.gov (United States)

    Li, Jian-Feng; Huang, Yi-Fan; Duan, Sai; Pang, Ran; Wu, De-Yin; Ren, Bin; Xu, Xin; Tian, Zhong-Qun

    2010-03-14

    The observed surface-enhanced Raman scattering (SERS) spectra of water adsorbed on metal film electrodes of silver, gold, and platinum nanoparticles were used to infer interfacial water structures on the basis of the change of the electrochemical vibrational Stark tuning rates and the relative Raman intensity of the stretching and bending modes. To explain the increase of the relative Raman intensity ratio of the bending and stretching vibrations at the very negative potential region, density functional theory calculations provide the conceptual model. The specific enhancement effect for the bending mode was closely associated with the water adsorption structure in a hydrogen bonded configuration through its H-end binding to surface sites with large polarizability due to strong cathodic polarization. The present results allow us to propose that interfacial water molecules exist on these metal cathodes with different hydrogen bonding interactions, i.e., the HO-HH-Pt dihydrogen bond for platinum and the HO-HAg(Au) for silver and gold. This dihydrogen bonding configuration on platinum is further supported from observation of the Pt-H stretching band. Furthermore, the influences of the pH effect on SERS intensity and vibrational Stark effect on the gold electrode indicate that the O-H stretching SERS signals are enhanced in the alkaline solutions because of the hydrated hydroxide surface species adsorbed on the gold cathode.

  12. Electrochemical investigation of electrodeposited platinum ...

    Indian Academy of Sciences (India)

    Hajar Mokarami Ghartavol

    2017-08-08

    Aug 8, 2017 ... nanoparticles on multi walled carbon nanotubes for methanol ... average size less than 100 nm was obtained in 0.5M H2SO4 solution, and the mean diameter of Pt crystals ... electrodes were rinsed in ethanol, and dried in air.

  13. Use of cyclic voltammetry and electrochemical impedance spectroscopy for determination of active surface area of modified carbon-based electrodes

    International Nuclear Information System (INIS)

    Souza, Leticia Lopes de

    2011-01-01

    Carbon-based electrodes as well the ion exchange electrodes among others have been applied mainly in the treatment of industrial effluents and radioactive wastes. Carbon is also used in fuel cells as substrate for the electrocatalysts, having high surface area which surpasses its geometric area. The knowledge of the total active area is important for the determination of operating conditions of an electrochemical cell with respect to the currents to be applied (current density). In this study it was used two techniques to determine the electrochemical active surface area of glassy carbon, electrodes and ion exchange electrodes: cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The experiments were carried out with KNO 3 0.1 mol.L -1 solutions in a three-electrode electrochemical cell: carbon-based working electrode, platinum auxiliary electrode and Ag/AgCl reference electrode. The glassy carbon and porous carbon electrodes with geometric areas of 3.14 x 10 -2 and 2.83 X 10 -1 cm 2 , respectively, were used. The ion exchange electrode was prepared by mixing graphite, carbon, ion exchange resin and a binder, and this mixture was applied in three layers on carbon felt, using a geometric area of 1.0 cm 2 during the experiments. The capacitance (Cd) of the materials was determined by EIS using Bode diagrams. The value of 172 μF.cm -2 found for the glassy carbon is consistent with the literature data (∼ 200 μF.cm'- 2 ). By VC, varying the scan rate from 0.2 to 2.0 mV.s-1, the capacitance CdS (S = active surface area) in the region of the electric double layer (EDL) of each material was determined. By EIS, the values of C d , 3.0 x 10 -5 μF.cm'- 2 and 11 x 10 3 μF.cm-2, were found for the porous carbon and ion exchange electrodes, respectively, which allowed the determination of active surface areas as 3.73 x 106 cm 2 and 4.72 cm 2 . To sum up, the combined use of EIS and CV techniques is a valuable tool for the calculation of active surface

  14. Electrochemical Deposition of Platinum and Palladium on Gold Nanoparticles Loaded Carbon Nanotube Support for Oxidation Reactions in Fuel Cell

    Directory of Open Access Journals (Sweden)

    Surin Saipanya

    2014-01-01

    Full Text Available Pt and Pd sequentially electrodeposited Au nanoparticles loaded carbon nanotube (Au-CNT was prepared for the electrocatalytic study of methanol, ethanol, and formic acid oxidations. All electrochemical measurements were carried out in a three-electrode cell. A platinum wire and Ag/AgCl were used as auxiliary and reference electrodes, respectively. Suspension of the Au-CNT, phosphate buffer, isopropanol, and Nafion was mixed and dropped on glassy carbon as a working electrode. By sequential deposition method, PdPtPt/Au-CNT, PtPdPd/Au-CNT, and PtPdPt/Au-CNT catalysts were prepared. Cyclic voltammograms (CVs of those catalysts in 1 M H2SO4 solution showed hydrogen adsorption and hydrogen desorption reactions. CV responses for those three catalysts in methanol, ethanol, and formic acid electrooxidations studied in 2 M CH3OH, CH3CH2OH, and HCOOH in 1 M H2SO4 show characteristic oxidation peaks. The oxidation peaks at anodic scan contribute to those organic substance oxidations while the peaks at cathodic scan are related with the reoxidation of the adsorbed carbonaceous species. Comparing all those three catalysts, it can be found that the PdPtPt/Au-CNT catalyst is good at methanol oxidation; the PtPdPt/Au-CNT effectively enhances ethanol oxidation while the PtPdPd/Au-CNT exceptionally catalyzes formic acid oxidation. Therefore, a different stoichiometry affects the electrochemical active surface area of the catalysts to achieve the catalytic oxidation reactions.

  15. Cermet electrode

    Science.gov (United States)

    Maskalick, Nicholas J.

    1988-08-30

    Disclosed is a cermet electrode consisting of metal particles of nickel, cobalt, iron, or alloys or mixtures thereof immobilized by zirconia stabilized in cubic form which contains discrete deposits of about 0.1 to about 5% by weight of praseodymium, dysprosium, terbium, or a mixture thereof. The solid oxide electrode can be made by covering a substrate with particles of nickel, cobalt, iron, or mixtures thereof, growing a stabilized zirconia solid oxide skeleton around the particles thereby immobilizing them, contacting the skeleton with a compound of praseodymium, dysprosium, terbium, or a mixture thereof, and heating the skeleton to a temperature of at least 500.degree. C. The electrode can also be made by preparing a slurry of nickel, cobalt, iron, or mixture and a compound of praseodymium, dysprosium, terbium, or a mixture thereof, depositing the slurry on a substrate, heating the slurry to dryness, and growing a stabilized zirconia skeleton around the metal particles.

  16. Electrochemical detection of copper ions leached from CuO nanoparticles in saline buffers and biological media using a gold wire working electrode

    Energy Technology Data Exchange (ETDEWEB)

    Baldisserri, Carlo, E-mail: carlo.baldisserri@istec.cnr.it; Costa, Anna Luisa [ISTEC-CNR (Italy)

    2016-04-15

    We performed explorative cyclic voltammetry in phosphate-buffered saline buffers, Dulbecco’s modified Eagle’s medium (DMEM), and fetal bovine serum-added DMEM using Au wire as working electrode, both in the absence and in the presence of known nominal concentrations of Cu{sup 2+} ions or 15 nm CuO nanoparticles. Addition of either Cu{sup 2+} ions or aqueous suspension of CuO nanoparticles caused a single anodic peak to appear in the double-layer region of all three pristine media. The height of the anodic peak was found to increase in a monotonic fashion vs. Cu{sup 2+} concentration in Cu{sup 2+}-added media, and versus time since CuO addition in CuO-added media. Stepwise addition of glycine to Cu{sup 2+}-added phosphate-buffered saline buffer caused an increasing cathodic shift of the anodic peak accompanied by decreasing peak currents. Results indicate that preparing Cu{sup 2+}-free suspensions of CuO nanoparticles in such media is difficult, owing to the presence of leached copper ions. The implications on results of experiments in which CuO nanoparticle-added biological media are used as cell culture substrates are discussed. Literature data on the interactions between Cu{sup 2+} ions, dissolved carbon dioxide in aqueous CuO suspensions, and amino acids present in such media are compared to our results.

  17. In situ electrochemical high-energy X-ray diffraction using a capillary working electrode cell geometry

    Energy Technology Data Exchange (ETDEWEB)

    Young, Matthias J.; Bedford, Nicholas M.; Jiang, Naisheng; Lin, Deqing; Dai, Liming

    2017-05-26

    The ability to generate new electrochemically active materials for energy generation and storage with improved properties will likely be derived from an understanding of atomic-scale structure/function relationships during electrochemical events. Here, the design and implementation of a new capillary electrochemical cell designed specifically forin situhigh-energy X-ray diffraction measurements is described. By increasing the amount of electrochemically active material in the X-ray path while implementing low-Zcell materials with anisotropic scattering profiles, an order of magnitude enhancement in diffracted X-ray signal over traditional cell geometries for multiple electrochemically active materials is demonstrated. This signal improvement is crucial for high-energy X-ray diffraction measurements and subsequent Fourier transformation into atomic pair distribution functions for atomic-scale structural analysis. As an example, clear structural changes in LiCoO2under reductive and oxidative conditions using the capillary cell are demonstrated, which agree with prior studies. Accurate modeling of the LiCoO2diffraction data using reverse Monte Carlo simulations further verifies accurate background subtraction and strong signal from the electrochemically active material, enabled by the capillary working electrode geometry.

  18. Electrochemical detection of copper ions leached from CuO nanoparticles in saline buffers and biological media using a gold wire working electrode

    Science.gov (United States)

    Baldisserri, Carlo; Costa, Anna Luisa

    2016-04-01

    We performed explorative cyclic voltammetry in phosphate-buffered saline buffers, Dulbecco's modified Eagle's medium (DMEM), and fetal bovine serum-added DMEM using Au wire as working electrode, both in the absence and in the presence of known nominal concentrations of Cu2+ ions or 15 nm CuO nanoparticles. Addition of either Cu2+ ions or aqueous suspension of CuO nanoparticles caused a single anodic peak to appear in the double-layer region of all three pristine media. The height of the anodic peak was found to increase in a monotonic fashion vs. Cu2+ concentration in Cu2+-added media, and versus time since CuO addition in CuO-added media. Stepwise addition of glycine to Cu2+-added phosphate-buffered saline buffer caused an increasing cathodic shift of the anodic peak accompanied by decreasing peak currents. Results indicate that preparing Cu2+-free suspensions of CuO nanoparticles in such media is difficult, owing to the presence of leached copper ions. The implications on results of experiments in which CuO nanoparticle-added biological media are used as cell culture substrates are discussed. Literature data on the interactions between Cu2+ ions, dissolved carbon dioxide in aqueous CuO suspensions, and amino acids present in such media are compared to our results.

  19. Electrochemical behavior of platinum nanoparticles on a carbon xerogel support modified with a [(trifluoromethyl)-benzenesulfonyl]imide electrolyte.

    Science.gov (United States)

    Liu, Bing; Mei, Hua; DesMarteau, Darryl; Creager, Stephen E

    2014-12-11

    A monoprotic [(trifluoromethyl)benzenesulfonyl]imide (SI) superacid electrolyte was used to covalently modify a mesoporous carbon xerogel (CX) support via reaction of the corresponding trifluoromethyl aryl sulfonimide diazonium zwitterion with the carbon surface. Electrolyte attachment was demonstrated by elemental analysis, acid-base titration, and thermogravimetric analysis. The ion-exchange capacity of the fluoroalkyl-aryl-sulfonimide-grafted carbon xerogel (SI-CX) was ∼0.18 mequiv g(-1), as indicated by acid-base titration. Platinum nanoparticles were deposited onto the SI-grafted carbon xerogel samples by the impregnation and reduction method, and these materials were employed to fabricate polyelectrolyte membrane fuel-cell (PEMFC) electrodes by the decal transfer method. The SI-grafted carbon-xerogel-supported platinum (Pt/SI-CX) was characterized by X-ray diffraction and transmission electron microscopy to determine platinum nanoparticle size and distribution, and the findings are compared with CX-supported platinum catalyst without the grafted SI electrolyte (Pt/CX). Platinum nanoparticle sizes are consistently larger on Pt/SI-CX than on Pt/CX. The electrochemically active surface area (ESA) of platinum catalyst on the Pt/SI-CX and Pt/CX samples was measured with ex situ cyclic voltammetry (CV) using both hydrogen adsorption/desorption and carbon monoxide stripping methods and by in situ CV within membrane electrode assemblies (MEAs). The ESA values for Pt/SI-CX are consistently lower than those for Pt/CX. Some possible reasons for the behavior of samples with and without grafted SI layers and implications for the possible use of SI-grafted carbon layers in PEMFC devices are discussed.

  20. Fabrication and characterization of implantable and flexible nerve cuff electrodes with Pt, Ir and IrOx films deposited by RF sputtering

    International Nuclear Information System (INIS)

    Lee, Soo Hyun; Jung, Jung Hwan; Chae, Youn Mee; Kang, Ji Yoon; Suh, Jun-Kyo Francis

    2010-01-01

    This paper presents the fabrication and characterization of implantable and flexible nerve cuff electrodes for neural interfaces using the conventional BioMEMS technique. In order to fabricate a flexible nerve electrode, polyimide (PI) was chosen as the substrate material. Then, nerve electrodes were thermally re-formed in a cuff shape so as to increase the area in which the charges were transferred to the nerve. Platinum (Pt), iridium (Ir) and iridium oxide (IrO x ) films, which were to serve as conducting materials for the nerve electrodes, were deposited at different working pressures by RF magnetron sputtering. The electrochemical properties of the deposited films were characterized by electrochemical impedance spectroscopy (EIS). The charge delivery capacities of the films were recorded and calculated by cyclic voltammetry (CV). The deposited films of Pt, Ir and IrO x have strong differences in electrochemical properties, which depend on the working pressure of sputter. Each film deposited at 30 mTorr of working pressure shows the highest value of charge delivery capacity (CDC). For the IrO x films, the electrochemical properties were strongly affected by the working pressure as well as the Ar:O 2 gas ratio. The IrO x film deposited with an Ar:O 2 gas ratio of 8:1 showed the highest CDC of 59.5 mC cm −2 , which was about five times higher than that of films deposited with a 1:1 gas ratio.

  1. Single Electrode Heat Effects

    DEFF Research Database (Denmark)

    Jacobsen, Torben; Broers, G. H. J.

    1977-01-01

    The heat evolution at a single irreversibly working electrode is treated onthe basis of the Brønsted heat principle. The resulting equation is analogous to the expression for the total heat evolution in a galvanic cellwith the exception that –DeltaS is substituted by the Peltier entropy, Delta......SP, of theelectrode reaction. eta is the overvoltage at the electrode. This equation is appliedto a high temperature carbonate fuel cell. It is shown that the Peltier entropyterm by far exceeds the heat production due to the irreversible losses, and thatthe main part of heat evolved at the cathode is reabsorbed...

  2. Platinum nanoparticles embedded in layer-by-layer films from SnO{sub 2}/polyallylamine for ethanol electrooxidation

    Energy Technology Data Exchange (ETDEWEB)

    Barretto, Caroline B.; Parreira, Renato L.T.; Goncalves, Rogeria R.; Huguenin, Fritz [Departamento de Quimica, Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, 14040-901 Ribeirao Preto SP (Brazil); de Azevedo, Dayse C. [NovoCell Energy Systems S.A., 13478-722 Americana SP (Brazil)

    2008-10-15

    Self-assembled films from SnO{sub 2} and polyallylamine (PAH) were deposited on gold via ionic attraction by the layer-by-layer (LbL) method. The modified electrodes were immersed into a H{sub 2}PtCl{sub 6} solution, a current of 100 {mu}A was applied, and different electrodeposition times were used. The SnO{sub 2}/PAH layers served as templates to yield metallic platinum with different particle sizes. The scanning tunnel microscopy images show that the particle size increases as a function of electrodeposition time. The potentiodynamic profile of the electrodes changes as a function of the electrodeposition time in 0.5 mol L{sup -1} H{sub 2}SO{sub 4}, at a sweeping rate of 50 mV s{sup -1}. Oxygen-like species are formed at less positive potentials for the Pt-SnO{sub 2}/PAH film in the case of the smallest platinum particles. Electrochemical impedance spectroscopy measurements in acid medium at 0.7 V show that the charge transfer resistance normalized by the exposed platinum area is 750 times greater for platinum electrode (300 k{omega} cm{sup 2}) compared with the Pt-SnO{sub 2}/PAH film with 1 min of electrodeposition (0.4 k{omega} cm{sup 2}). According to the Langmuir-Hinshelwood bifunctional mechanism, the high degree of coverage with oxygen-like species on the platinum nanoparticles is responsible for the electrocatalytic activity of the Pt-SnO{sub 2}/PAH concerning ethanol electrooxidation. With these features, this Pt-SnO{sub 2}/PAH film may be grown on a proton exchange membrane (PEM) in direct ethanol fuel cells (DEFC). (author)

  3. Electro-catalytic oxidation of ethanol on platinum-iridium mixtures supported on glassy carbon

    International Nuclear Information System (INIS)

    Rodriguez, Henry; Hoyos Bibian

    2004-01-01

    Electro-catalytic oxidation of ethanol on platinum-iridium mixtures supported on glassy carbon was studied, in acid media at different temperatures and concentrations. During the maturation time of deposited iridium, the surface is covered by an irreversible oxide formation, which affects the behavior of the catalytic mixture. The Pt 7 0 Ir 3 0 and Pt 9 0 Ir 1 0 mixtures seem to be a little more active than the Pt/C electrode at potentials below 800 mV (vs. HRE). In all electrodes appears two reactions: partial ethanol oxidation to produce acetaldehyde (main path of reaction at low temperatures and high electrode coverage with ethanol adsorption residues) and the total oxidation to carbon dioxide which is considerable at potential above 800 mV and it is increased with increasing temperature

  4. Activation analysis for platinum in gold and metals of the platinum group through 199Au

    International Nuclear Information System (INIS)

    Foerster, H.

    1976-01-01

    Platinum was determined in gold and in metals of the platinum group through 199 Au by activation analysis. The matrix was separated at the end of irradiation before the daughter nuclide was formed. Gold was separated by extraction with MIBK from 1

  5. Magnetohydrodynamic electrode

    International Nuclear Information System (INIS)

    1980-01-01

    The object of the invention is the provision of a material capable of withstanding a high-temperature, corrosive and erosive environment for use as a ceramic-metal composite electrode current collector in the channel of a magnetohydrodynamic generator. (U.K.)

  6. Nanofiber-deposited porous platinum enables glucose fuel cell anodes with high current density in body fluids

    Science.gov (United States)

    Frei, Maxi; Erben, Johannes; Martin, Julian; Zengerle, Roland; Kerzenmacher, Sven

    2017-09-01

    The poisoning of platinum anodes by body-fluid constituents such as amino acids is currently the main hurdle preventing the application of abiotic glucose fuel cells as battery-independent power supply for medical implants. We present a novel anode material that enables continuous operation of glucose oxidation anodes in horse serum for at least 30 days at a current density of (7.2 ± 1.9) μA cm-2. The fabrication process is based on the electro-deposition of highly porous platinum onto a 3-dimensional carbon nanofiber support, leading to approximately 2-fold increased electrode roughness factors (up to 16500 ± 2300). The material's superior performance is not only related to its high specific surface area, but also to an improved catalytic activity and/or poisoning resistance. Presumably, this results from the micro- and nanostructure of the platinum deposits. This represents a major step forward in the development of implantable glucose fuel cells based on long-term stable platinum electrodes.

  7. Solvent extraction of platinum with thiobenzanilide. Separation of platinum from copper

    International Nuclear Information System (INIS)

    Shkil', A.N.; Zolotov, Yu.A.

    1989-01-01

    The solvent extraction of micro concentrations of platinum has been investigated from hydrochloric acid media using thiobenzanilide in the presence of SnCl 2 and KI. In the presence of SnCl 2 platinum is extracted rapidly and to significant completion. Conditions have been developed for the quantitative extraction of platinum. The authors have also examined the solvent extraction of copper(II) using thiobenzanilide, interference due to copper(II) and iron(III) on solvent extraction of platinum, and methods to suppress this interference. A procedure has also been developed for the separation of platinum from copper. Solvent extraction of metals was studied using radioactive isotopes: 197 Pt, 64 Cu, 59 Fe, 198 Au, 109 Pd, 110m Ag

  8. Pulse-voltammetric glucose detection at gold junction electrodes.

    Science.gov (United States)

    Rassaei, Liza; Marken, Frank

    2010-09-01

    A novel glucose sensing concept based on the localized change or "modulation" in pH within a symmetric gold-gold junction electrode is proposed. A paired gold-gold junction electrode (average gap size ca. 500 nm) is prepared by simultaneous bipotentiostatic electrodeposition of gold onto two closely spaced platinum disk electrodes. For glucose detection in neutral aqueous solution, the potential of the "pH-modulator" electrode is set to -1.5 V vs saturated calomel reference electrode (SCE) to locally increase the pH, and simultaneously, either cyclic voltammetry or square wave voltammetry experiments are conducted at the sensor electrode. A considerable improvement in the sensor electrode response is observed when a normal pulse voltammetry sequence is applied to the modulator electrode (to generate "hydroxide pulses") and the glucose sensor electrode is operated with fixed bias at +0.5 V vs SCE (to eliminate capacitive charging currents). Preliminary data suggest good linearity for the glucose response in the medically relevant 1-10 mM concentration range (corresponding to 0.18-1.8 g L(-1)). Future electroanalytical applications of multidimensional pulse voltammetry in junction electrodes are discussed.

  9. LDRD final report on synthesis of shape-and size-controlled platinum and platinum alloy nanostructures on carbon with improved durability.

    Energy Technology Data Exchange (ETDEWEB)

    Shelnutt, John Allen; Garcia, Robert M.; Song, Yujiang; Moreno, Andres M.; Stanis, Ronald J.

    2008-10-01

    This project is aimed to gain added durability by supporting ripening-resistant dendritic platinum and/or platinum-based alloy nanostructures on carbon. We have developed a new synthetic approach suitable for directly supporting dendritic nanostructures on VXC-72 carbon black (CB), single-walled carbon nanotubes (SWCNTs), and multi-walled carbon nanotubes (MWCNTs). The key of the synthesis is to creating a unique supporting/confining reaction environment by incorporating carbon within lipid bilayer relying on a hydrophobic-hydrophobic interaction. In order to realize size uniformity control over the supported dendritic nanostructures, a fast photocatalytic seeding method based on tin(IV) porphyrins (SnP) developed at Sandia was applied to the synthesis by using SnP-containing liposomes under tungsten light irradiation. For concept approval, one created dendritic platinum nanostructure supported on CB was fabricated into membrane electrode assemblies (MEAs) for durability examination via potential cycling. It appears that carbon supporting is essentially beneficial to an enhanced durability according to our preliminary results.

  10. Improvement of light harvesting and device performance of dye-sensitized solar cells using rod-like nanocrystal TiO{sub 2} overlay coating on TiO{sub 2} nanoparticle working electrode

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xueyang; Fang, Jian [Institute for Frontier Materials, Deakin University, VIC 3220 (Australia); Gao, Mei [CSIRO Materials Science and Engineering, Melbourne, VIC 3169 (Australia); Wang, Hongxia [Institute for Frontier Materials, Deakin University, VIC 3220 (Australia); Yang, Weidong [CSIRO Materials Science and Engineering, Melbourne, VIC 3169 (Australia); Lin, Tong, E-mail: tong.lin@deakin.edu.au [Institute for Frontier Materials, Deakin University, VIC 3220 (Australia)

    2015-02-01

    Novel TiO{sub 2} single crystalline nanorods were synthesized by electrospinning and hydrothermal treatment. The role of the TiO{sub 2} nanorods on TiO{sub 2} nanoparticle electrode in improvement of light harvesting and photovoltaic properties of dye-sensitized solar cells (DSSCs) was examined. Although the TiO{sub 2} nanorods had lower dye loading than TiO{sub 2} nanoparticle, they showed higher light utilization behaviour. Electron transfer in TiO{sub 2} nanorods received less resistance than that in TiO{sub 2} nanoparticle aggregation. By just applying a thin layer of TiO{sub 2} nanorods on TiO{sub 2} nanoparticle working electrode, the DSSC device light harvesting ability and energy conversion efficiency were improved significantly. The thickness of the nanorod layer in the working electrode played an important role in determining the photovoltaic property of DSSCs. An energy conversion efficiency as high as 6.6% was found on a DSSC device with the working electrode consisting of a 12 μm think TiO{sub 2} nanoparticle layer covered with 3 μm thick TiO{sub 2} nanorods. The results obtained from this study may benefit further design of highly efficient DSSCs. - Highlights: • Single crystalline TiO{sub 2} nanorods were prepared for DSSC application. • TiO{sub 2} nanorods show effective light scattering performance. • TiO{sub 2} nanorods have higher electron transfer efficiency than TiO{sub 2} nanoparticles. • TiO{sub 2} nanorods on TiO{sub 2} nanoparticle electrode improve DSSC efficiency.

  11. Improvement of light harvesting and device performance of dye-sensitized solar cells using rod-like nanocrystal TiO2 overlay coating on TiO2 nanoparticle working electrode

    International Nuclear Information System (INIS)

    Liu, Xueyang; Fang, Jian; Gao, Mei; Wang, Hongxia; Yang, Weidong; Lin, Tong

    2015-01-01

    Novel TiO 2 single crystalline nanorods were synthesized by electrospinning and hydrothermal treatment. The role of the TiO 2 nanorods on TiO 2 nanoparticle electrode in improvement of light harvesting and photovoltaic properties of dye-sensitized solar cells (DSSCs) was examined. Although the TiO 2 nanorods had lower dye loading than TiO 2 nanoparticle, they showed higher light utilization behaviour. Electron transfer in TiO 2 nanorods received less resistance than that in TiO 2 nanoparticle aggregation. By just applying a thin layer of TiO 2 nanorods on TiO 2 nanoparticle working electrode, the DSSC device light harvesting ability and energy conversion efficiency were improved significantly. The thickness of the nanorod layer in the working electrode played an important role in determining the photovoltaic property of DSSCs. An energy conversion efficiency as high as 6.6% was found on a DSSC device with the working electrode consisting of a 12 μm think TiO 2 nanoparticle layer covered with 3 μm thick TiO 2 nanorods. The results obtained from this study may benefit further design of highly efficient DSSCs. - Highlights: • Single crystalline TiO 2 nanorods were prepared for DSSC application. • TiO 2 nanorods show effective light scattering performance. • TiO 2 nanorods have higher electron transfer efficiency than TiO 2 nanoparticles. • TiO 2 nanorods on TiO 2 nanoparticle electrode improve DSSC efficiency

  12. Electrode Processes in Porous Electrodes.

    Science.gov (United States)

    1985-11-26

    F104470 2.0 MASS SPECTROMETRY One part of activity for this year is an investigation of the behavior of silver electrodes through the distribution of...al. (2)). These, in some cases, involve tedious and time comsuming procedures and discrepencies of as much as 15% have been observed in the results. As

  13. Improved open-circuit voltage in Cu(In,Ga)Se{sub 2} solar cells with high work function transparent electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Jäger, Timo, E-mail: timo.jaeger@empa.ch; Romanyuk, Yaroslav E.; Bissig, Benjamin; Pianezzi, Fabian; Nishiwaki, Shiro; Reinhard, Patrick; Steinhauser, Jérôme; Tiwari, Ayodhya N. [Empa—Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Thin Films and Photovoltaics, Überlandstrasse 129, 8600 Dübendorf (Switzerland); Schwenk, Johannes [Empa—Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Nanoscale Materials Science, Überlandstrasse 129, 8600 Dübendorf (Switzerland)

    2015-06-14

    Hydrogenated indium oxide (IOH) is implemented as transparent front contact in Cu(In,Ga)Se{sub 2} (CIGS) solar cells, leading to an open circuit voltage V{sub OC} enhanced by ∼20 mV as compared to reference devices with ZnO:Al (AZO) electrodes. This effect is reproducible in a wide range of contact sheet resistances corresponding to various IOH thicknesses. We present the detailed electrical characterization of glass/Mo/CIGS/CdS/intrinsic ZnO (i-ZnO)/transparent conductive oxide (TCO) with different IOH/AZO ratios in the front TCO contact in order to identify possible reasons for the enhanced V{sub OC}. Temperature and illumination intensity-dependent current-voltage measurements indicate that the dominant recombination path does not change when AZO is replaced by IOH, and it is mainly limited to recombination in the space charge region and at the junction interface of the solar cell. The main finding is that the introduction of even a 5 nm-thin IOH layer at the i-ZnO/TCO interface already results in a step-like increase in V{sub OC}. Two possible explanations are proposed and verified by one-dimensional simulations using the SCAPS software. First, a higher work function of IOH as compared to AZO is simulated to yield an V{sub OC} increase by 21 mV. Second, a lower defect density in the i-ZnO layer as a result of the reduced sputter damage during milder sputter-deposition of IOH can also add to a maximum enhanced V{sub OC} of 25 mV. Our results demonstrate that the proper choice of the front TCO contact can reduce the parasitic recombination and boost the efficiency of CIGS cells with improved corrosion stability.

  14. Testing electrode suitability for field stimulation of high-threshold biological preparations

    Directory of Open Access Journals (Sweden)

    Hugo Fernando Maia Milan

    Full Text Available IntroductionA problem posed by electrical field (E stimulation of biological preparations with high excitation threshold is that the E intensity required for excitation is likely to induce water electrolysis at the electrode surface, which can alter the extracellular medium and cause deleterious effects on the cells. In this study, different electrode materials and geometries were tested aiming at identifying electrode configurations that could transduce the E intensity required for exciting ventricular cardiomyocytes isolated from neonatal rats (threshold E ~30 V/cm without causing water electrolysis.MethodsWire and plate electrodes made of platinum, stainless steel and nickel/chrome alloy were used. The effect of blasting the electrode surface with sand and NaHCO3 solution was also tested. Electrodes were inserted into a cell perfusion chamber containing the saline solution routinely used for physiological experiments. During E application for 5 min, the electrode surface and its surroundings were examined at high magnification for the presence of microbubbles, which indicates the occurrence of water electrolysis. The greatest E intensity applied that failed to generate microbubbles (En was estimated.ResultsWhile nickel/chrome and stainless steel electrodes resulted in low En values, the best performance was observed for sandblasted platinum wire (2 mm diameter and plate (25 mm x 5 mm; 0.1 mm thickness electrodes, for which Enwas ≥40 V/cm.ConclusionThese electrode configurations are suitable for effective and safe stimulation of isolated neonatal cardiomyocytes.

  15. Amperometric and coulometric methods of platinum metal determination. (Review)

    International Nuclear Information System (INIS)

    Ezerskaya, N.A.

    1981-01-01

    Reviewed are works published in the period from 1957-1979, on amperometric and coulometric (potentiostatistic and amperostatistic variant) determination of platinum metals, Ru in particular. During amperometric titration of Ru the following titrantes are used: hydroquinone, thioxne thiourea, Na 2 S 2 O 3 . It is proposed to titrate Ru in the form of ruthenate-ion with hydrazine sulphate in alkal: medium according to the current of reagent oxidation. During coulometric determination of Ru the electrogenerating titrant TiCl 3 or Ti 2 (SO 4 ) 3 (for initial form of Ru [RuCl 6 ] 2- ) is used [ru

  16. Stability and phase transfer of catalytically active platinum nanoparticle suspensions

    International Nuclear Information System (INIS)

    Sriram, Indira; Curtin, Alexandra E.; Chiaramonti, Ann N.; Cuchiaro, J. Hunter; Weidner, Andrew R.; Tingley, Tegan M.; Greenlee, Lauren F.; Jeerage, Kavita M.

    2015-01-01

    In this work, we present a robust synthesis protocol for platinum nanoparticles that yields a monomodal dispersion of particles that are approximately 100 nm in diameter. We determine that these particles are actually agglomerates of much smaller particles, creating a “raspberry” morphology. We demonstrate that these agglomerates are stable at room temperature for at least 8 weeks by dynamic light scattering. Furthermore, we demonstrate consistent electrocatalytic activity for methanol oxidation. Finally, we quantitatively explore the relationship between dispersion solvent and particle agglomeration; specifically, particles are found to agglomerate abruptly as solvent polarity decreases

  17. Stability and phase transfer of catalytically active platinum nanoparticle suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Sriram, Indira; Curtin, Alexandra E.; Chiaramonti, Ann N.; Cuchiaro, J. Hunter; Weidner, Andrew R.; Tingley, Tegan M.; Greenlee, Lauren F.; Jeerage, Kavita M., E-mail: jeerage@boulder.nist.gov [National Instrument of Standards and Technology, Applied Chemicals and Materials Division (United States)

    2015-05-15

    In this work, we present a robust synthesis protocol for platinum nanoparticles that yields a monomodal dispersion of particles that are approximately 100 nm in diameter. We determine that these particles are actually agglomerates of much smaller particles, creating a “raspberry” morphology. We demonstrate that these agglomerates are stable at room temperature for at least 8 weeks by dynamic light scattering. Furthermore, we demonstrate consistent electrocatalytic activity for methanol oxidation. Finally, we quantitatively explore the relationship between dispersion solvent and particle agglomeration; specifically, particles are found to agglomerate abruptly as solvent polarity decreases.

  18. Simple fabrication of active electrodes using direct laser transference

    International Nuclear Information System (INIS)

    Cavallo, P.; Coneo Rodriguez, R.; Broglia, M.; Acevedo, D.F.; Barbero, C.A.

    2014-01-01

    Highlights: •Electroactive materials can be transferred using a single pulse of laser light. •The transfer is made in air using a 6 ns pulse of Nd-YAG laser (532 or 1064 nm). •Conducting polymers films can be transferred maintaining the electroactivity. •Conducting polymer multilayers can be deposited using successive pulses. •Metallic (Au, Pt) transferred micro/nanoparticles are electrocatalytic. -- Abstract: Direct laser transference (DLT) method is applied to obtain electrodes modified with thin films of conducting polymers (CPs) or catalytic metals. A short (6–10 ns) pulse of laser light (second harmonic of Nd-YAG Laser, λ = 532 nm) is shined on the backside of a thin (<200 nm) film of the material to be transferred, which is deposited on a transparent substrate. The illuminated region heats up and the material (conducting polymer or metal) is thermally transferred to a solid target placed at short distance in air. In that ways, CPs are transferred onto polypropylene, glass, indium doped tin oxide (ITO), glassy carbon and gold films. In the same manner, electrocatalytic metals (platinum or gold) are transferred onto conductive substrates (glassy carbon or ITO films on glass). The films have been characterized by scanning electron microscopy, cyclic voltammetry, atomic force microscopy, UV-visible and Fourier Transform Infrared spectroscopies. The chemical, electrical and redox properties of the polymeric materials transferred remain unaltered after the transfer. Moreover, CP multilayers can be built applying DLT several times onto the same substrate. Besides polyaniline, it is shown that it is also possible to transfer functionalized polyanilines. The electrode modified with transferred Pt shows electrocatalytic activity toward methanol oxidation while ferricyanide shows a quasireversible behavior on electrodes modified with transferred Au. The method is simple and fast, works in air without complex environmental conditions and can produce active

  19. The photovoltaic performance of Ag2S quantum dots-sensitized solar cells using plasmonic Au nanoparticles/TiO2 working electrodes

    Science.gov (United States)

    Badawi, Ali; Mostafa, Nasser Y.; Al-Hosiny, Najm M.; Merazga, Amar; Albaradi, Ateyyah M.; Abdel-Wahab, F.; Atta, A. A.

    2018-06-01

    The photovoltaic performance of silver sulfide (Ag2S) quantum dots-sensitized solar cells (QDSSCs) using different concentrations (0, 0.05, 0.1, 0.3 and 0.5 wt.%) of plasmonic Au nanoparticles (NPs)/titania (TiO2) electrodes has been investigated. Ag2S quantum dots (QDs) were adsorbed onto the Au NPs/titania electrodes using the successive ionic layer adsorption and reaction (SILAR) deposition technique. The morphological properties of the Au NPs and the prepared titania electrodes were characterized using transmission electron microscope (TEM) and scanning electron microscope (SEM), respectively. The energy-dispersive X-ray (EDX) spectra of the bare titania and Ag2S QDs-sensitized titania electrodes were recorded. The optical properties of the prepared Ag2S QDs-sensitized titania electrodes were measured using a UV-visible spectrophotometer. The estimated energy band gap of Ag2S QDs-sensitized titania electrodes is 1.96 eV. The photovoltaic performance of the assembled Ag2S QDSSCs was measured under 100 mW/cm2 solar illumination. The optimal photovoltaic parameters were obtained as follows: open circuit voltage Voc = 0.50 V, current density Jsc = 3.18 mA/cm2, fill factor (FF) = 0.35 and energy conversion efficiency η = 0.55% for 0.3 wt.% of Au NPs/titania electrode. These results are attributed to the enhancement in the absorption and decrease in the electron-hole pairs recombination rate. The open circuit voltage decay (OCVD) measurements of the assembled Ag2S QDSSCs were measured. The calculated electron lifetime (τ) in Ag2S QDSSCs with Au NPs/titania electrodes is at least one order of magnitude more than that with bare titania electrode. The cut-on-cut-off cycles of the solar illumination measurements show the rapid sensitivity and good reproducibility of the assembled Ag2S QDSSCs.

  20. Novel platinum black electroplating technique improving mechanical stability.

    Science.gov (United States)

    Kim, Raeyoung; Nam, Yoonkey

    2013-01-01

    Platinum black microelectrodes are widely used as an effective neural signal recording sensor. The simple fabrication process, high quality signal recording and proper biocompatibility are the main advantages of platinum black microelectrodes. When microelectrodes are exposed to actual biological system, various physical stimuli are applied. However, the porous structure of platinum black is vulnerable to external stimuli and destroyed easily. The impedance level of the microelectrode increases when the microelectrodes are damaged resulting in decreased recording performance. In this study, we developed mechanically stable platinum black microelectrodes by adding polydopamine. The polydopamine layer was added between the platinum black structures by electrodeposition method. The initial impedance level of platinum black only microelectrodes and polydopamine added microelectrodes were similar but after applying ultrasonication the impedance value dramatically increased for platinum black only microelectrodes, whereas polydopamine added microelectrodes showed little increase which were nearly retained initial values. Polydopamine added platinum black microelectrodes are expected to extend the availability as neural sensors.

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

    Directory of Open Access Journals (Sweden)

    Drygała A.

    2016-06-01

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

  2. TEM and EELS studies of microwave-irradiation synthesis of bimetallic platinum nanocatalysts

    International Nuclear Information System (INIS)

    Mathe, N R; Scriba, M R; Coville, N J; Olivier, J E

    2014-01-01

    Microwave-irradiation (MW) synthesis of nanostructured materials provides for the synthesis of metal nanoparticles, using fast and uniform heating rates. This procedure affords better control of the shape and size of the nanoparticles when compared to conventional methods. In this work, microwave-irradiation was used to produce platinum-cobalt (Pt-Co) and platinum-nickel (Pt-Ni) nanoparticles for use as electrocatalysts in the methanol oxidation reaction. High resolution TEM imaging and EELS studies revealed that these bimetallic nanoparticles form islands or hetero-structures

  3. Electrodeposition of gold-platinum alloy nanoparticles on carbon nanotubes as electrochemical sensing interface for sensitive detection of tumor marker

    Energy Technology Data Exchange (ETDEWEB)

    Li Ya [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Yuan Ruo, E-mail: yuanruo@swu.edu.cn [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China); Chai Yaqin; Song Zhongju [Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715 (China)

    2011-07-30

    Graphical abstract: Electrodeposition of gold-platinum alloy (Au-PtNPs) on carbon nanotubes as electrochemical sensing interface and HRP as blocking agent for the fabrication of high sensitive immunosensor. Display Omitted Highlights: > In this work, we proposed a novel electrochemical sensing surface. > The sensing surface possessed larger electro-active areas and higher conductivity due to the introduction of MWCNTs. > The signal could be amplified effectively by synergetic catalysis effect of Au-PtNPs and HRP towards the reduction of H{sub 2}O{sub 2}. > Biomolecules could be immobilized on the surface of Au-PtNPs tightly with the bioactivity kept well. > The simple fabrication method provided a new potential for the future development of practical devices for clinical diagnosis application. - Abstract: A novel electrochemical sensing interface, electrodeposition of gold-platinum alloy nanoparticles (Au-PtNPs) on carbon nanotubes, was proposed and used to fabricate a label-free amperometric immunosensor. On the one hand, the multiwalled carbon nanotubes (MWCNTs) could increase active area of the electrode and enhance the electron transfer ability between the electrode and redox probe; on the other hand, the Au-PtNPs not only could be used to assemble biomolecules with bioactivity kept well, but also could further facilitate the shuttle of electrons. In the meanwhile, horseradish peroxidase (HRP) instead of bovine serum albumin (BSA) was employed to block the possible remaining active sites and avoid the nonspecific adsorption. With the synergetic catalysis effect of Au-PtNPs and HRP towards the reduction of hydrogen peroxide (H{sub 2}O{sub 2}), the signal could be amplified and the sensitivity could be enhanced. Using alpha-fetoprotein (AFP) as model analyte, the fabricated immunosensor exhibited two wide linear ranges in the concentration ranges of 0.5-20 ng mL{sup -1} and 20-200 ng mL{sup -1} with a detection limit of 0.17 ng mL{sup -1} at a signal-to-noise of

  4. The industrial application of a uranium dioxide electrode

    International Nuclear Information System (INIS)

    Needes, C.R.S.; Nicol, M.J.; Finkelstein, N.P.; Ormrod, G.T.W.

    1975-01-01

    A correlation between the potential of a UO 2 electrode and the rate of recovery of uranium has been proved in laboratory and plant trials. When the recovery rates change because of variation in the concentrations of Fe(III), Fe(II), SO 2- 4 , and H + , a positive correlation is observed. However, an increase in the concentration of phosphate in solution produces an increase in the UO 2 electrode potential but a decrease in the rate of leaching of UO 2 . The correlation between the UO 2 electrode potential and the rate of leaching of UO 2 is then negative. It is concluded that, as a control device, the electrode cannot compete with the platinum electrode for use on certain plants. Nevertheless, the UO 2 electrode will act as a useful warning device if the total concentration of iron in solution decreases to below a level concomitant with the economic recovery of uranium. Furthermore, because of the positive correlation between the UO 2 electrode potential and the phosphate concentration, the electrode will also be of value in the detection of an increase in the phosphate level in solution. When it was incorporated in a suitable industrial probe, the electrode was found to be able to withstand the rigours of the leaching conditions in a large pilot-plant pachuca, and only failed after six weeks operation [af

  5. Ultra-fine Pt nanoparticles on graphene aerogel as a porous electrode with high stability for microfluidic methanol fuel cell

    Science.gov (United States)

    Kwok, Y. H.; Tsang, Alpha C. H.; Wang, Yifei; Leung, Dennis Y. C.

    2017-05-01

    Platinum-decorated graphene aerogel as a porous electrode for flow-through direct methanol microfluidic fuel cell is introduced. Ultra-fine platinum nanoparticles with size ranged from diameter 1.5 nm-3 nm are evenly anchored on the graphene nanosheets without agglomeration. The electrode is characterized by scanning electron microscopy, transmission electron microscopy and energy-dispersive X-ray spectroscopy. Catalytic activity is confirmed by cyclic voltammetry. The electroactive surface area and catalytic activity of platinum on graphene oxide (Pt/GO) are much larger than commercial platinum on carbon black (Pt/C). A counterflow microfluidic fuel cell is designed for contrasting the cell performance between flow-over type and flow-through type electrodes using Pt/C on carbon paper and Pt/GO, respectively. The Pt/GO electrode shows 358% increment in specific power compared with Pt/C anode. Apart from catalytic activity, the effect of porous electrode conductivity to cell performance is also studied. The conductivity of the porous electrode should be further enhanced to achieve higher cell performance.

  6. Studying the glial cell response to biomaterials and surface topography for improving the neural electrode interface

    Science.gov (United States)

    Ereifej, Evon S.

    Neural electrode devices hold great promise to help people with the restoration of lost functions, however, research is lacking in the biomaterial design of a stable, long-term device. Current devices lack long term functionality, most have been found unable to record neural activity within weeks after implantation due to the development of glial scar tissue (Polikov et al., 2006; Zhong and Bellamkonda, 2008). The long-term effect of chronically implanted electrodes is the formation of a glial scar made up of reactive astrocytes and the matrix proteins they generate (Polikov et al., 2005; Seil and Webster, 2008). Scarring is initiated when a device is inserted into brain tissue and is associated with an inflammatory response. Activated astrocytes are hypertrophic, hyperplastic, have an upregulation of intermediate filaments GFAP and vimentin expression, and filament formation (Buffo et al., 2010; Gervasi et al., 2008). Current approaches towards inhibiting the initiation of glial scarring range from altering the geometry, roughness, size, shape and materials of the device (Grill et al., 2009; Kotov et al., 2009; Kotzar et al., 2002; Szarowski et al., 2003). Literature has shown that surface topography modifications can alter cell alignment, adhesion, proliferation, migration, and gene expression (Agnew et al., 1983; Cogan et al., 2005; Cogan et al., 2006; Merrill et al., 2005). Thus, the goals of the presented work are to study the cellular response to biomaterials used in neural electrode fabrication and assess surface topography effects on minimizing astrogliosis. Initially, to examine astrocyte response to various materials used in neural electrode fabrication, astrocytes were cultured on platinum, silicon, PMMA, and SU-8 surfaces, with polystyrene as the control surface. Cell proliferation, viability, morphology and gene expression was measured for seven days in vitro. Results determined the cellular characteristics, reactions and growth rates of astrocytes

  7. Silicon/SU8 multi-electrode micro-needle for in vivo neurochemical monitoring.

    Science.gov (United States)

    Vasylieva, Natalia; Marinesco, Stéphane; Barbier, Daniel; Sabac, Andrei

    2015-10-15

    Simultaneous monitoring of glucose and lactate is an important challenge for understanding brain energetics in physiological or pathological states. We demonstrate here a versatile method based on a minimally invasive single implantation in the rat brain. A silicon/SU8-polymer multi-sensing needle-shaped biosensor, was fabricated and tested. The multi-electrode array design comprises three platinum planar microelectrodes with a surface area of 40 × 200 µm(2) and a spacing of 200 µm, which were micromachined on a single 3mm long micro-needle having a 100 × 50 µm(2) cross-section for reduced tissue damage during implantation. Platinum micro-electrodes were aligned at the bottom of micro-wells obtained by photolithography on a SU8 photoresist layer. After clean room processing, each micro-electrode was functionalized inside the micro-wells by means of a micro-dispensing device, either with glucose oxidase or with lactate oxidase, which were cross-linked on the platinum electrodes. The third electrode covered with Bovine Serum Albumin (BSA) was used for the control of non-specific currents. The thick SU8 photoresist layer has revealed excellent electrical insulation of the micro-electrodes and between interconnection lines, and ensured a precise localization and packaging of the sensing enzymes on platinum micro-electrodes. During in vitro calibration with concentrations of analytes in the mM range, the micro-wells patterned in the SU8 photoresist proved to be highly effective in eliminating cross-talk signals, caused by H2O2 diffusion from closely spaced micro-electrodes. Moreover, our biosensor was successfully assayed in the rat cortex for simultaneous monitoring of both glucose and lactate during insulin and glucose administration. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Characterisation of nano-interdigitated electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Skjolding, L H D; Ribayrol, A; Montelius, L [Division of Solid State Physics, Lund University, Box 118, SE-221 00 Lund (Sweden); Spegel, C [Department of Analytical Chemistry Lund University, Box 124, SE-221 00 Lund (Sweden); Emneus, J [MIC - Department of Micro and Nanotechnology, DTU - Building 345 East, DK-2800 Kgs. Lyngby (Denmark)], E-mail: lars_henrik.daehli_skjolding@ftf.lth.se

    2008-03-15

    Interdigitated electrodes made up of two individually addressable interdigitated comb-like electrode structures have frequently been suggested as ultra sensitive electrochemical biosensors. Since the signal enhancement effects due to cycling of the reduced and oxidized species are strongly dependent on the inter electrode distances, since the nature of the enhancement is due to overlying diffusion layers, interdigitated electrodes with an electrode separation of less then one micrometer are desired for maximum signal amplification. Fabrication of submicron structures can only be made by advanced lithography techniques. By use of electron beam lithography we have fabricated arrays of interdigitated electrodes with an electrode separation distance of 200 nm and an electrode finger width of likewise 200 nm. The entire electrode structure is 100 micrometre times 100 micrometre, and the active electrode area is dictated by the opening in the passivation layer, that is defined by UV lithography. Here we report measurements of redox cycling of ferrocyanide by coupled cyclic voltammograms, where the potential at one of the working electrodes are varied and either an oxidising or reducing potential is applied to the complimentary interdigitated electrode. The measurements show fast conversion and high collection efficiency round 87% as expected for nano-interdigitated electrodes.

  9. Ultrahigh PEMFC performance of a thin-film, dual-electrode assembly with tailored electrode morphology.

    Science.gov (United States)

    Jung, Chi-Young; Kim, Tae-Hyun; Yi, Sung-Chul

    2014-02-01

    A dual-electrode membrane electrode assembly (MEA) for proton exchange membrane fuel cells with enhanced polarization under zero relative humidity (RH) is fabricated by introducing a phase-separated morphology in an agglomerated catalyst layer of Pt/C (platinum on carbon black) and Nafion. In the catalyst layer, a sufficient level of phase separation is achieved by dispersing the Pt catalyst and the Nafion dispersion in a mixed-solvent system (propane-1,2,3-triol/1-methyl-2-pyrrolidinone).The high polymer chain mobility results in improved water uptake and regular pore-size distribution with small pore diameters. The electrochemical performance of the dual-film electrode assembly with different levels of phase separation is compared to conventional electrode assemblies. As a result, good performance at 0 % RH is obtained because self-humidification is dramatically improved by attaching this dense and phase-separated catalytic overlayer onto the conventional catalyst layer. A MEA prepared using the thin-film, dual-layered electrode exhibits 39-fold increased RH stability and 28-fold improved start-up recovery time during the on-off operation relative to the conventional device. We demonstrate the successful operation of the dual-layered electrode comprised of discriminatively phase-separated agglomerates with an ultrahigh zero RH fuel-cell performance reaching over 95 % performance of a fully humidified MEA. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Phosphorescent Organic Light Emitting Diodes Implementing Platinum Complexes

    Science.gov (United States)

    Ecton, Jeremy Exton

    Organic light emitting diodes (OLEDs) are a promising approach for display and solid state lighting applications. However, further work is needed in establishing the availability of efficient and stable materials for OLEDs with high external quantum efficiency's (EQE) and high operational lifetimes. Recently, significant improvements in the internal quantum efficiency or ratio of generated photons to injected electrons have been achieved with the advent of phosphorescent complexes with the ability to harvest both singlet and triplet excitons. Since then, a variety of phosphorescent complexes containing heavy metal centers including Os, Ni, Ir, Pd, and Pt have been developed. Thus far, the majority of the work in the field has focused on iridium based complexes. Platinum based complexes, however, have received considerably less attention despite demonstrating efficiency's equal to or better than their iridium analogs. In this study, a series of OLEDs implementing newly developed platinum based complexes were demonstrated with efficiency's or operational lifetimes equal to or better than their iridium analogs for select cases. In addition to demonstrating excellent device performance in OLEDs, platinum based complexes exhibit unique photophysical properties including the ability to form excimer emission capable of generating broad white light emission from a single emitter and the ability to form narrow band emission from a rigid, tetradentate molecular structure for select cases. These unique photophysical properties were exploited and their optical and electrical properties in a device setting were elucidated. Utilizing the unique properties of a tridentate Pt complex, Pt-16, a highly efficient white device employing a single emissive layer exhibited a peak EQE of over 20% and high color quality with a CRI of 80 and color coordinates CIE(x=0.33, y=0.33). Furthermore, by employing a rigid, tetradentate platinum complex, PtN1N, with a narrow band emission into a

  11. The role of adsorbates in the electrochemical oxidation of ammonia on noble and transition metal electrodes

    NARCIS (Netherlands)

    Vooys, de A.C.A.; Koper, M.T.M.; Santen, van R.A.; Veen, van J.A.R.

    2001-01-01

    The activity for ammonia oxidation and the intermediates formed during the reaction have been studied on platinum, palladium, rhodium, ruthenium, iridium, copper, silver and gold electrodes. The activity in the selective oxidation to N-2 is related directly to the nature of the species at the

  12. Electrode materials for microbial fuel cells: nanomaterial approach

    KAUST Repository

    Mustakeem, Mustakeem

    2015-11-05

    Microbial fuel cell (MFC) technology has the potential to become a major renewable energy resource by degrading organic pollutants in wastewater. The performance of MFC directly depends on the kinetics of the electrode reactions within the fuel cell, with the performance of the electrodes heavily influenced by the materials they are made from. A wide range of materials have been tested to improve the performance of MFCs. In the past decade, carbon-based nanomaterials have emerged as promising materials for both anode and cathode construction. Composite materials have also shown to have the potential to become materials of choice for electrode manufacture. Various transition metal oxides have been investigated as alternatives to conventional expensive metals like platinum for oxygen reduction reaction. In this review, different carbon-based nanomaterials and composite materials are discussed for their potential use as MFC electrodes.

  13. Electrode materials for microbial fuel cells: nanomaterial approach

    KAUST Repository

    Mustakeem, Mustakeem

    2015-01-01

    Microbial fuel cell (MFC) technology has the potential to become a major renewable energy resource by degrading organic pollutants in wastewater. The performance of MFC directly depends on the kinetics of the electrode reactions within the fuel cell, with the performance of the electrodes heavily influenced by the materials they are made from. A wide range of materials have been tested to improve the performance of MFCs. In the past decade, carbon-based nanomaterials have emerged as promising materials for both anode and cathode construction. Composite materials have also shown to have the potential to become materials of choice for electrode manufacture. Various transition metal oxides have been investigated as alternatives to conventional expensive metals like platinum for oxygen reduction reaction. In this review, different carbon-based nanomaterials and composite materials are discussed for their potential use as MFC electrodes.

  14. Urinary excretion of platinum, arsenic and selenium of cancer patients from the Antofagasta region in Chile treated with platinum-based drugs

    Directory of Open Access Journals (Sweden)

    Román Domingo A

    2012-04-01

    Full Text Available Abstract Background Arsenic exposure increases the risk of non-cancerous and cancerous diseases. In the Antofagasta region in Chile, an established relationship exists between arsenic exposure and the risk of cancer of the bladder, lung and skin. Platinum-based drugs are first-line treatments, and many works recognise selenium as a cancer-fighting nutrient. We characterised the short-term urinary excretion amounts of arsenic, selenium and platinum in 24-h urine samples from patients with lung cancer and those with cancer other than lung treated with cisplatin or/and carboplatin. As - Se - Pt inter-element relationships were also investigated. Results The amounts of platinum excreted in urine were not significantly different between patients with lung cancer and those with other cancers treated with cisplatin, despite the significant variation in platinum amounts supplied from platinum-based drugs. In general, the analytical amounts of excreted selenium were greater than those for arsenic, which could imply that platinum favours the excretion of selenium. For other types of cancers treated with drugs without platinum, excretion of selenium was also greater than that of arsenic, suggesting an antagonist selenium-anti-cancer drug relationship. Conclusions Regards the baseline status of patients, the analytical amounts of excreted Se is greater than those for As, particularly, for cisplatin chemotherapy. This finding could imply that for over the As displacement Pt favours the excretion of Se. The analytical amounts of excreted Se were greater than those for As, either with and without Pt-containing drugs, suggesting an antagonist Se-anti-cancer drug relationship. However, it seemed that differences existed between As - Se - Pt inter-element associations in patients treated for lung cancer in comparison with those treated for cancer other than lung. Therefore, knowledge obtained in this work, can contribute to understanding the arsenic cancer

  15. Platinum recycling in the United States in 1998

    Science.gov (United States)

    Hilliard, Henry E.

    2001-01-01

    In the United States, catalytic converters are the major source of secondary platinum for recycling. Other sources of platinum scrap include reforming and chemical process catalysts. The glass industry is a small but significant source of platinum scrap. In North America, it has been estimated that in 1998 more than 20,000 kilograms per year of platinum-group metals from automobile catalysts were available for recycling. In 1998, an estimated 7,690 kilograms of platinum were recycled in the United States. U.S. recycling efficiency was calculated to have been 76 percent in 1998; the recycling rate was estimated at 16 percent.

  16. Outpatient desensitization in selected patients with platinum hypersensitivity reactions.

    Science.gov (United States)

    O'Malley, David M; Vetter, Monica Hagan; Cohn, David E; Khan, Ambar; Hays, John L

    2017-06-01

    Platinum-based chemotherapies are a standard treatment for both initial and recurrent gynecologic cancers. Given this widespread use, it is important to be aware of the features of platinum hypersensitivity reactions and the subsequent treatment of these reactions. There is also increasing interest in the development of desensitization protocols to allow patients with a history of platinum hypersensitivity to receive further platinum based therapy. In this review, we describe the management of platinum hypersensitivity reactions and the desensitization protocols utilized at our institution. We also describe the clinical categorizations utilized to triage patients to appropriate desensitization protocols. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. On the enzymatic formation of platinum nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Govender, Y.; Riddin, T. L. [Rhodes University, Department of Biochemistry, Microbiology and Biotechnology (South Africa); Gericke, M. [MINTEK (South Africa); Whiteley, C. G., E-mail: C.Whiteley@ru.ac.z [Rhodes University, Department of Biochemistry, Microbiology and Biotechnology (South Africa)

    2010-01-15

    A dimeric hydrogenase enzyme (44.5 and 39.4 kDa sub units) was isolated in a 39.5% yield from the fungus Fusarium oxysporum and purified 4.64-fold by ion exchange chromatography on Sephacryl S-200. Characterisation of the enzyme afforded pH and temperature optima of 7.5 and 38 {sup o}C, respectively, a half-life stability of 36 min and a V{sub max} and K{sub m} of 3.57 nmol min{sup -1} mL{sup -1} and 2.25 mM, respectively. This enzyme was inhibited (non-competitively) by hydrogen hexachloroplatinic acid (H{sub 2}PtCl{sub 6}) at 1 or 2 mM with a K{sub i} value of 118 {mu}M. Incubation of the platinum salt with the pure enzyme under an atmosphere of hydrogen and optimum enzyme conditions (pH 7.5, 38 {sup o}C) afforded <10% bioreduction after 8 h while at conditions suitable for platinum nanoparticle formation (pH 9, 65 {sup o}C) over 90% reduction took place after the same length of time. Cell-free extract from the fungal isolates produced nearly 90% bioreduction of the platinum salt under both pH and temperature conditions. The bioreduction of the platinum salt by a hydrogenase enzyme takes place by a passive process and not an active one as previously understood.

  18. Rockburst damage mechanism at Impala Platinum Mine

    CSIR Research Space (South Africa)

    Ledwaba, LS

    2012-05-01

    Full Text Available Impala Platinum Mine (Impala), situated north of the town of Rustenburg in the North West Province of South Africa, has experienced an increase in seismicity from ~841 seismic events in the year 2005 to ~1588 seismic events in 2008...

  19. Platinum nanoparticles functionalized nitrogen doped graphene platform for sensitive electrochemical glucose biosensing

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Zhanjun, E-mail: zjyang@yzu.edu.cn; Cao, Yue; Li, Juan; Jian, Zhiqin; Zhang, Yongcai; Hu, Xiaoya

    2015-04-29

    Highlights: • An efficient PtNPs@NG nanocomposite was prepared for the immobilization of enzyme. • A novel electrochemical glucose biosensor was constructed based on this PtNPs@NG. • The proposed glucose biosensor showed high sensitivity and low detection limit. • The PtNPs@NG composite provided a promising platform for biosensing applications. - Abstract: In this work, we reported an efficient platinum nanoparticles functionalized nitrogen doped graphene (PtNPs@NG) nanocomposite for devising novel electrochemical glucose biosensor for the first time. The fabricated PtNPs@NG and biosensor were characterized using transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, static water contact angle, UV–vis spectroscopy, electrochemical impedance spectra and cyclic voltammetry, respectively. PtNPs@NG showed large surface area and excellent biocompatibility, and enhanced the direct electron transfer between enzyme molecules and electrode surface. The glucose oxidase (GOx) immobilized on PtNPs@NG nanocomposite retained its bioactivity, and exhibited a surface controlled, quasi-reversible and fast electron transfer process. The constructed glucose biosensor showed wide linear range from 0.005 to 1.1 mM with high sensitivity of 20.31 mA M{sup −1} cm{sup −2}. The detection limit was calculated to be 0.002 mM at signal-to-noise of 3, which showed 20-fold decrease in comparison with single NG-based electrochemical biosensor for glucose. The proposed glucose biosensor also demonstrated excellent selectivity, good reproducibility, acceptable stability, and could be successfully applied in the detection of glucose in serum samples at the applied potential of −0.33 V. This research provided a promising biosensing platform for the development of excellent electrochemical biosensors.

  20. Platinum nanoparticles functionalized nitrogen doped graphene platform for sensitive electrochemical glucose biosensing

    International Nuclear Information System (INIS)

    Yang, Zhanjun; Cao, Yue; Li, Juan; Jian, Zhiqin; Zhang, Yongcai; Hu, Xiaoya

    2015-01-01

    Highlights: • An efficient PtNPs@NG nanocomposite was prepared for the immobilization of enzyme. • A novel electrochemical glucose biosensor was constructed based on this PtNPs@NG. • The proposed glucose biosensor showed high sensitivity and low detection limit. • The PtNPs@NG composite provided a promising platform for biosensing applications. - Abstract: In this work, we reported an efficient platinum nanoparticles functionalized nitrogen doped graphene (PtNPs@NG) nanocomposite for devising novel electrochemical glucose biosensor for the first time. The fabricated PtNPs@NG and biosensor were characterized using transmission electron microscopy, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, static water contact angle, UV–vis spectroscopy, electrochemical impedance spectra and cyclic voltammetry, respectively. PtNPs@NG showed large surface area and excellent biocompatibility, and enhanced the direct electron transfer between enzyme molecules and electrode surface. The glucose oxidase (GOx) immobilized on PtNPs@NG nanocomposite retained its bioactivity, and exhibited a surface controlled, quasi-reversible and fast electron transfer process. The constructed glucose biosensor showed wide linear range from 0.005 to 1.1 mM with high sensitivity of 20.31 mA M −1 cm −2 . The detection limit was calculated to be 0.002 mM at signal-to-noise of 3, which showed 20-fold decrease in comparison with single NG-based electrochemical biosensor for glucose. The proposed glucose biosensor also demonstrated excellent selectivity, good reproducibility, acceptable stability, and could be successfully applied in the detection of glucose in serum samples at the applied potential of −0.33 V. This research provided a promising biosensing platform for the development of excellent electrochemical biosensors

  1. Electrode for improving electrochemical measurements in high temperature water

    International Nuclear Information System (INIS)

    Sengarsai, T.

    2005-01-01

    A silver/silver-chloride (Ag/AgCl) reference electrode was specially designed and constructed in a body of oxidized titanium for potentiometric measurements under high-temperature and high-pressure conditions. To avoid the thermal decomposition of silver-chloride, the electrode is designed to maintain the reference element at low temperature while it is still connected to high-temperature process zone via a non-isothermal electrolyte bridge. This configuration leads to the development of a thermal gradient along the length of the electrode. At room temperature, the stability of the Ag/AgCl reference electrode versus a standard calomel electrode (SCE) is maintained with an accuracy of 5 mV. The electrode's performance at high temperature and pressure (up to 300 o C and 1500 psi) was examined by measuring the potential difference against platinum, which acted as a reversible hydrogen electrode (RHE). Comparison of the experimental and theoretical values verifies the reliability and reproducibility of the electrode. Deviation from the Nernst equation is considered and related to the thermal liquid junction potential (TLJP). An empirical correction factor is used to maintain the Ag/AgCl potential within an acceptable accuracy limit of ±20 mV at high temperature. (author)

  2. Platinum-gold nanoclusters as catalyst for direct methanol fuel cells.

    Science.gov (United States)

    Giorgi, L; Giorgi, R; Gagliardi, S; Serra, E; Alvisi, M; Signore, M A; Piscopiello, E

    2011-10-01

    Nanosized platinum-gold alloys clusters have been deposited on gas diffusion electrode by sputter deposition. The deposits were characterized by FE-SEM, TEM and XPS in order to verify the formation of alloy nanoparticles and to study the influence of deposition technique on the nanomorphology. The deposition by sputtering process allowed a uniform distribution of metal particles on porous surface of carbon supports. Typical island growth mode was observed with the formation of a dispersed metal nanoclusters (mean size about 5 nm). Cyclic voltammetry was used to determine the electrochemical active surface and the electrocatalytic performance of the PtAu electrocatalysts for methanol oxidation reaction. The data were re-calculated in the form of mass specific activity (MSA). The sputter-catalyzed electrodes showed higher performance and stability compared to commercial catalysts.

  3. The Effect of Platinum Electrocatalyst on Membrane Degradation in Polymer Electrolyte Fuel Cells.

    Science.gov (United States)

    Bodner, Merit; Cermenek, Bernd; Rami, Mija; Hacker, Viktor

    2015-12-08

    Membrane degradation is a severe factor limiting the lifetime of polymer electrolyte fuel cells. Therefore, obtaining a deeper knowledge is fundamental in order to establish fuel cells as competitive product. A segmented single cell was operated under open circuit voltage with alternating relative humidity. The influence of the catalyst layer on membrane degradation was evaluated by measuring a membrane without electrodes and a membrane-electrode-assembly under identical conditions. After 100 h of accelerated stress testing the proton conductivity of membrane samples near the anode and cathode was investigated by means of ex situ electrochemical impedance spectroscopy. The membrane sample near the cathode inlet exhibited twofold lower membrane resistance and a resulting twofold higher proton conductivity than the membrane sample near the anode inlet. The results from the fluoride ion analysis have shown that the presence of platinum reduces the fluoride emission rate; which supports conclusions drawn from the literature.

  4. New highly active oxygen reduction electrode for PEM fuel cell and Zn/air battery applications (NORA). Final report

    Energy Technology Data Exchange (ETDEWEB)

    Thiele, D.; Zuettel, A.

    2008-04-15

    This illustrated final report for the Swiss Federal Office of Energy (SFOE) presents the results of a project concerning a new, highly active oxygen reduction electrode for PEM fuel cell and zinc/air battery applications. The goal of this project was, according to the authors, to increase the efficiency of the oxygen reduction reaction by lowering the activation polarisation through the right choice of catalyst and by lowering the concentration polarisation. In this work, carbon nanotubes are used as support material. The use of these nanotubes grown on perovskites is discussed. Theoretical considerations regarding activation polarisation are discussed and alternatives to the use of platinum are examined. The results of experiments carried out are presented in graphical and tabular form. The paper is completed with a comprehensive list of references.

  5. Mesostructured platinum-free anode and carbon-free cathode catalysts for durable proton exchange membrane fuel cells.

    Science.gov (United States)

    Cui, Xiangzhi; Shi, Jianlin; Wang, Yongxia; Chen, Yu; Zhang, Lingxia; Hua, Zile

    2014-01-01

    As one of the most important clean energy sources, proton exchange membrane fuel cells (PEMFCs) have been a topic of extensive research focus for decades. Unfortunately, several critical technique obstacles, such as the high cost of platinum electrode catalysts, performance degradation due to the CO poisoning of the platinum anode, and carbon corrosion by oxygen in the cathode, have greatly impeded its commercial development. A prototype of a single PEMFC catalyzed by a mesostructured platinum-free WO3/C anode and a mesostructured carbon-free Pt/WC cathode catalysts is reported herein. The prototype cell exhibited 93% power output of a standard PEMFC using commercial Pt/C catalysts at 50 and 70 °C, and more importantly, CO poisoning-free and carbon corrosion-resistant characters of the anode and cathode, respectively. Consequently, the prototype cell demonstrated considerably enhanced cell operation durability. The mesostructured electrode catalysts are therefore highly promising in the future development and application of PEMFCs. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Mechanistic Switching by Hydronium Ion Activity for Hydrogen Evolution and Oxidation over Polycrystalline Platinum Disk and Platinum/Carbon Electrodes

    KAUST Repository

    Shinagawa, Tatsuya; Garcia Esparza, Angel T.; Takanabe, Kazuhiro

    2014-01-01

    is not affected by pH and the supporting electrolyte type, is required for electrocatalysis in both directions. This ion independence, including pH, suggests that HER/HOR performance under neutral conditions solely reflects the intrinsic electrocatalytic activity

  7. Reactions of neopentane and neohexane on platinum/Y-zeolite and platinum/silica catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Foger, K.; Anderson, J.R.

    1978-10-13

    The hydrocracking/hydroisomerization reaction of 20:1 hydrogen/neopentane at 455-625/sup 0/K was studied on platinum-exchanged sodium, calcium, and lanthanum Y zeolites and Aerosil-supported platinum of 1-20 nm average platinum particle size, by analysis of the product distribution, ESCA, and temperature-programed desorption. The results suggested that the reaction occurs only on platinum and that it proceeds by two parallel pathways which have different activation energies and whose relative proportion depends on the particle size. One pathway is the conventionally accepted one on low-index crystallite facets; the other proceeds on single-surface platinum atoms of low coordination (corner or edge atoms) which become more abundant at lower crystallite size. In both cases, the adsorbed intermediate may undergo either isomerization or hydrogenolysis; the selectivity depends on the hydrogen partial pressure and the relative strength of adsorption of hydrogen and neopentane. Neohexane isomerization selectivity on the same catalysts is consistent with a carbonium ion mechanism on a dual-function catalyst.

  8. Comparative study of on-line response time measurement methods for platinum resistance thermometer

    International Nuclear Information System (INIS)

    Zwingelstein, G.; Gopal, R.

    1979-01-01

    This study deals with the in site determination of the response time of platinum resistance sensor. In the first part of this work, two methods furnishing the reference response time of the sensors are studied. In the second part of the work, two methods obtaining the response time without dismounting of the sensor, are studied. A comparative study of the performances of these methods is included for fluid velocities varying from 0 to 10 m/sec, in both laboratory and plant conditions

  9. Ni-BaTiO3-Based Base-Metal Electrode (BME) Ceramic Capacitors for Space Applications

    Science.gov (United States)

    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.

  10. Efficient electrochemical regeneration of nicotinamide cofactors using a cyclopentadienyl-rhodium complex on functionalized indium tin oxide electrodes

    International Nuclear Information System (INIS)

    Kim, Soojin; Lee, Ga Ye; Lee, Jungha; Rajkumar, Eswaran; Baeg, Jin-Ook; Kim, Jinheung

    2013-01-01

    Functionalized ITO electrodes are used to regenerate NADH using [Cp*Rh(bpy)(H 2 O)] 2+ (Cp* = pentamethylcyclopentadienyl, bpy = 2,2′-bipyridine) electrochemically in a buffer solution. Amino- and mercapto-functionalized electrodes featured higher activity and stability for electrocatalytic generation of NADH than a bare ITO electrode. Effect of metal nanoparticles was also studied on modified ITO electrodes and the addition of platinum nanoparticles even resulted in improved activity. The electrochemical regeneration was somewhat affected in the presence of dioxygen, but not significantly. In addition, a conversion of carbon dioxide was carried out utilizing the electrochemically generated NADH and formate dehydrogenase to produce formic acid

  11. Conducting polymers based counter electrodes for dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Veerender, P., E-mail: veeru1009@gmail.com, E-mail: veeru1009@gmail.com; Saxena, Vibha, E-mail: veeru1009@gmail.com, E-mail: veeru1009@gmail.com; Gusain, Abhay, E-mail: veeru1009@gmail.com, E-mail: veeru1009@gmail.com; Jha, P., E-mail: veeru1009@gmail.com, E-mail: veeru1009@gmail.com; Koiry, S. P., E-mail: veeru1009@gmail.com, E-mail: veeru1009@gmail.com; Chauhan, A. K., E-mail: veeru1009@gmail.com, E-mail: veeru1009@gmail.com; Aswal, D. K., E-mail: veeru1009@gmail.com, E-mail: veeru1009@gmail.com; Gupta, S. K., E-mail: veeru1009@gmail.com, E-mail: veeru1009@gmail.com [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai - 400085 (India)

    2014-04-24

    Conducting polymer films were synthesized and employed as an alternative to expensive platinum counter electrodes for dye-sensitized solar cells. poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) thin films were spin-coated and polypyrrole films were electrochemically deposited via cyclic voltammetry method on ITO substrates. The morphology of the films were imaged by SEM and AFM. These films show good catalytic activity towards triiodide reduction as compared to Pt/FTO electrodes. Finally the photovoltaic performance of DSSC fabricated using N3 dye were compared with PT/FTO, PEDOT/ITO, and e-PPy counter electrodes.

  12. Flexible transparent electrode

    Science.gov (United States)

    Demiryont, Hulya; Shannon, Kenneth C., III; Moorehead, David; Bratcher, Matthew

    2011-06-01

    This paper presents the properties of the EclipseTECTM transparent conductor. EclipseTECTM is a room temperature deposited nanostructured thin film coating system comprised of metal-oxide semiconductor elements. The system possesses metal-like conductivity and glass-like transparency in the visible region. These highly conductive TEC films exhibit high shielding efficiency (35dB at 1 to 100GHz). EclipseTECTM can be deposited on rigid or flexible substrates. For example, EclipseTECTM deposited on polyethylene terephthalate (PET) is extremely flexible that can be rolled around a 9mm diameter cylinder with little or no reduction in electrical conductivity and that can assume pre-extension states after an applied stress is relieved. The TEC is colorless and has been tailored to have high visible transmittance which matches the eye sensitivity curve and allows the viewing of true background colors through the coating. EclipseTECTM is flexible, durable and can be tailored at the interface for applications such as electron- or hole-injecting OLED electrodes as well as electrodes in flexible displays. Tunable work function and optical design flexibility also make EclipseTECTM well-suited as a candidate for grid electrode replacement in next-generation photovoltaic cells.

  13. Electrochemical behavior of titanium implanted with platinum

    International Nuclear Information System (INIS)

    Thompson, N.G.; Lichter, B.D.; Appleton, B.R.; Kelly, E.J.; White, C.W.

    1979-01-01

    The following conclusions apply to Ti(Pt) near-surface alloys studied. (1) Open-circuit corrosion measurements show that accumulation of platinum may occur at a surface concentration of 0.32 atomic percent Pt while no accumulation occurs at 0.16 atomic percent Pt. However, these results do not allow a distinction as to cause of accumulation to be made between concentration effects and effects due to the presence of an oxide film. (2) Potentiostatic corrosion at -0.450 V (active corrosion) establish that little or no accumulation of platinum occurs at an oxide-free surface for concentrations less than 0.086 atomic percent Pt; whereas, a large amount of accumulation occurs for a distribution with a peak concentration of 0.83 atomic percent Pt. (3) An initial distribution having a peak concentration of 0.32 atomic percent platinum is sufficient to induce natural passivity in titanium and bring a freely corroding sample to a potential of 0.269 V. This is nearly the applicable reversible potential (-0.260 V) for the hydrogen reaction in 1N H 2 SO 4 . (4) Of three samples which showed accumulation, platinum was eventually lost for two of these samples (0.32 atomic percent, open-circuit corrosion; 0.83 atomic percent, potentiostatic corrosion). The remaining sample (9.1 atomic percent, open-circuit corrosion) maintained the maximum possible potential of -0.260 V for the length of the experiment (approx. 30 days). (5) For samples which had been polarized at -0.300 to -0.340 V and which had eventually reverted to the behavior of pure Ti, post corrosion RBS measurements reveal that a substantial fraction of the Pt fluence is retained on the surface in an electrochemically inactive state

  14. On the enzymatic formation of platinum nanoparticles

    International Nuclear Information System (INIS)

    Govender, Y.; Riddin, T. L.; Gericke, M.; Whiteley, C. G.

    2010-01-01

    A dimeric hydrogenase enzyme (44.5 and 39.4 kDa sub units) was isolated in a 39.5% yield from the fungus Fusarium oxysporum and purified 4.64-fold by ion exchange chromatography on Sephacryl S-200. Characterisation of the enzyme afforded pH and temperature optima of 7.5 and 38 o C, respectively, a half-life stability of 36 min and a V max and K m of 3.57 nmol min -1 mL -1 and 2.25 mM, respectively. This enzyme was inhibited (non-competitively) by hydrogen hexachloroplatinic acid (H 2 PtCl 6 ) at 1 or 2 mM with a K i value of 118 μM. Incubation of the platinum salt with the pure enzyme under an atmosphere of hydrogen and optimum enzyme conditions (pH 7.5, 38 o C) afforded o C) over 90% reduction took place after the same length of time. Cell-free extract from the fungal isolates produced nearly 90% bioreduction of the platinum salt under both pH and temperature conditions. The bioreduction of the platinum salt by a hydrogenase enzyme takes place by a passive process and not an active one as previously understood.

  15. Platinum boride nanowires: Synthesis and characterization

    International Nuclear Information System (INIS)

    Ding Zhanhui; Qiu Lixia; Zhang Jian; Yao Bin; Cui Tian; Guan Weiming; Zheng Weitao; Wang Wenquan; Zhao Xudong; Liu Xiaoyang

    2012-01-01

    Highlights: ► Platinum boride nanowires have been synthesized via the direct current arc discharge method. ► XRD, TEM and SAED indicate that the nanowires are single-crystal PtB. ► Two broad photoluminescence emission peaks at about 586 nm and 626 nm have been observed in the PL spectroscopy of PtB nanowires. - Abstract: Platinum boride (PtB) nanowires have been successfully fabricated with direct current arc discharge method using a milled mixture of platinum (Pt) and boron nitride (BN) powders. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the compositions, morphology, and structures of the samples. The results show that PtB nanowires are 30–50 nm thick and 20–30 μm long. TEM and selected area electron diffraction (SAED) patterns identify that the PtB nanowires are single-crystalline in nature. A growth mechanism based on vapor–liquid–solid (VLS) process is proposed for the formation of nanowires.

  16. Oxygen electrodes for energy conversion and storage. Annual report, 1 October 1977-30 September 1978

    Energy Technology Data Exchange (ETDEWEB)

    None

    1980-01-15

    Research on the development of high performance, long life O/sub 2/ cathodes for both alkaline and acid electrolytes for a spectrum of applications including industrial electrolysis, fuel cells, and metal-air batteries is described. Oxygen electrocatalysts studied include platinum, silver, underpotential deposited layers and alloy metal layers on noble metal substrates, intercalated graphite, transition metal macrocyclic complexes, and transition metal oxides. Research on gas fed electrodes is also described. Results are presented and discussed in detail. An appendix on the electrodeposition of platinum crystallites on graphite substrates is included. (WHK)

  17. Recovery of Platinum from Dilute Chloride Media Using Biosorbents

    Science.gov (United States)

    Zeytuncu, B.; Morcali, M. H.; Yucel, O.

    Pistachio nut shells and Rice husk, a biomass residue, were investigated as adsorbents for the platinum uptake from synthetically prepared dilute chloroplatinic acid solutions. The effects of the different uptake parameters on platinum uptake (%) were studied in detail on a batch sorption. Before the pistachio nut shell material was activated, platinum uptake (%) was poor compared with rice husk. However, after the pistachio nut shell material was activated at 1000°C under an argon atmosphere, the platinum uptake (%) increased two-fold. The pistachio nut shell (inactivated and activated) and rice husk were characterized by Attenuated Total Reflection-Fourier transform infrared spectroscopy (ATR-FTIR).

  18. Platinum Jubilee 1934-2009

    Indian Academy of Sciences (India)

    2009-03-12

    Mar 12, 2009 ... ... parasitology, vaccine development, malaria, molecular and cell ... zoonotic disease diagnostics and vaccine development. ... has given rise to much work in the development of ..... lipases; synthesis of diacylglycerol, the anti besity oil; .... the preparation of new functional solids; chemistry in zeolites ...

  19. Fabrication and Characterisation of Membrane-Based Gold Electrodes

    DEFF Research Database (Denmark)

    Bakmand, Tanya; Kwasny, Dorota; Dimaki, Maria

    2015-01-01

    This work presents a versatile, membrane based electrochemical sensor with thin film electrodes fabricated through Ebeam evaporation directly on porous materials (membranes). Here, the fabrication of the electrodes is described along with possible methods for integration in fluidic systems...

  20. Heterogeneous time-resolved electrochemiluminoimmunoassay of thyroid stimulating hormone with magnetic beads at oxide-covered aluminum electrode

    Energy Technology Data Exchange (ETDEWEB)

    Ala-Kleme, Timo, E-mail: timo.ala-kleme@utu.fi

    2017-06-15

    The heterogeneous immunoassay of thyroid stimulating hormone (TSH) was detected by the time-resolved cathodic electrochemiluminescence immunoassay (tr-CECLIA) method using magnetic beads as a mobile support. The magnetic beads coated with sandwich type TSH immunoassay were captured with a magnet for washing and detection processes. The time-resolved cathodic electrochemiluminescence (tr-CECL) signal of Tb(III) chelate label was generated by cathodic pulse polarization in the aluminum working electrode and platinum counter electrode system. The detection method causes injection of high energy electrons into the aqueous solution near the aluminum electrode and creates rigid simultaneous oxidative and reductive conditions that excitate the Tb(III) chelate used as a label luminophore in the heterogeneous sandwich type immunoassay of TSH in the surface of the magnetic beads. The limit of detection of the method was about 50 mIU L{sup −1}. The precision of it was noticed to be good; the coefficient variation percentage was realized to be lower than 10 %. Unfortunately the limit of detection is not good enough for determination of analyte levels of very low concentrations for instance TSH in body fluids. The possible application areas of the method are in highly sophisticated micro or nano fluidic detection and sensor systems where the aspiration level of the analyte detection limit is not very high and the mobility and manageability and the large surface area of the magnetic beads can be utilized efficiently in separating, washing, moving, coating and detecting processes. In the case of tr-CECLIA the presented method makes possible to use multipurpose working electrodes instead of disposable ones.

  1. ORGANIC ELECTRODE COATINGS FOR NEXT-GENERATION NEURAL INTERFACES

    Directory of Open Access Journals (Sweden)

    Ulises A Aregueta-Robles

    2014-05-01

    Full Text Available Traditional neuronal interfaces utilize metallic electrodes which in recent years have reached a plateau in terms of the ability to provide safe stimulation at high resolution or rather with high densities of microelectrodes with improved spatial selectivity. To achieve higher resolution it has become clear that reducing the size of electrodes is required to enable higher electrode counts from the implant device. The limitations of interfacing electrodes including low charge injection limits, mechanical mismatch and foreign body response can be addressed through the use of organic electrode coatings which typically provide a softer, more roughened surface to enable both improved charge transfer and lower mechanical mismatch with neural tissue. Coating electrodes with conductive polymers or carbon nanotubes offers a substantial increase in charge transfer area compared to conventional platinum electrodes. These organic conductors provide safe electrical stimulation of tissue while avoiding undesirable chemical reactions and cell damage. However, the mechanical properties of conductive polymers are not ideal, as they are quite brittle. Hydrogel polymers present a versatile coating option for electrodes as they can be chemically modified to provide a soft and conductive scaffold. However, the in vivo chronic inflammatory response of these conductive hydrogels remains unknown. A more recent approach proposes tissue engineering the electrode interface through the use of encapsulated neurons within hydrogel coatings. This approach may provide a method for activating tissue at the cellular scale, however several technological challenges must be addressed to demonstrate feasibility of this innovative idea. The review focuses on the various organic coatings which have been investigated to improve neural interface electrodes.

  2. Electrocatalytic reduction of nitrate at low concentration on coinage and transition-metal electrodes in acid solutions

    NARCIS (Netherlands)

    Dima, G.E.; Vooys, de A.C.A.; Koper, M.T.M.

    2003-01-01

    A comparative study was performed to determine the reactivity of nitrate ions at 0.1 M on eight different polycrystalline electrodes (platinum, palladium, rhodium, ruthenium, iridium, copper, silver and gold) in acidic solution using cyclic voltammetry (CV), chronoamperometry and differential

  3. Noninvasive estimation of bound and mobile platinum compounds in the kidney using a radiopharmacokinetic model

    International Nuclear Information System (INIS)

    Brechner, R.R.; D'Argenio, D.Z.; Dahalan, R.; Wolf, W.

    1986-01-01

    Nephrotoxicity remains a major limitation in the use of cisplatin [cis-diamminedichloroplatinum(II)]. Although several strategies are in use to limit this serious side effect, none is fully satisfactory. Classical pharmacokinetic studies of cisplatin have been based on blood and urine samples. As nephrotoxicity plays a significant role in the design of the therapeutic strategy, the kidneys should be considered as a separate state in any model formulated for ultimate control purposes. Previous studies of organ pharmacokinetics have relied on population measurements. The authors have developed an organ compartmental model from individual animal data obtained noninvasively. The eight-compartment model used to represent the distribution of cisplatin considers free and bound platinum in plasma, platinum in the erythrocytes, mobile and bound platinum in the kidneys, mobile and bound platinum in the tissues, and platinum in the urine. Data were collected from experiments with anesthetized female rats, after intravenous administration of [195mPt]cisplatin. Both arterial and bladder samples, and multiple images obtained with an Anger camera interfaced to a microcomputer were used. The model was estimated from individual data obtained after injection of a bolus of cisplatin (six animals). The model was validated by using it to predict data obtained from forcing the system with a different input function, a 0.5-h intravenous infusion (three animals). The results of this work show that it is possible to noninvasively study drug kinetics in organs that are not readily accessible to direct measurements in an individual, rather than relying on invasive measurements performed on a population.(ABSTRACT TRUNCATED AT 250 WORDS)

  4. Cochlear Dummy Electrodes for Insertion Training and Research Purposes: Fabrication, Mechanical Characterization, and Experimental Validation

    Directory of Open Access Journals (Sweden)

    Jan-Philipp Kobler

    2015-01-01

    Full Text Available To develop skills sufficient for hearing preservation cochlear implant surgery, surgeons need to perform several electrode insertion trials in ex vivo temporal bones, thereby consuming relatively expensive electrode carriers. The objectives of this study were to evaluate the insertion characteristics of cochlear electrodes in a plastic scala tympani model and to fabricate radio opaque polymer filament dummy electrodes of equivalent mechanical properties. In addition, this study should aid the design and development of new cochlear electrodes. Automated insertion force measurement is a new technique to reproducibly analyze and evaluate the insertion dynamics and mechanical characteristics of an electrode. Mechanical properties of MED-EL’s FLEX28, FLEX24, and FLEX20 electrodes were assessed with the help of an automated insertion tool. Statistical analysis of the overall mechanical behavior of the electrodes and factors influencing the insertion force are discussed. Radio opaque dummy electrodes of comparable characteristics were fabricated based on insertion force measurements. The platinum-iridium wires were replaced by polymer filament to provide sufficient stiffness to the electrodes and to eradicate the metallic artifacts in X-ray and computed tomography (CT images. These low-cost dummy electrodes are cheap alternatives for surgical training and for in vitro, ex vivo, and in vivo research purposes.

  5. Facile fabrication of novel silver-polypyrrole-multiwall carbon nanotubes nanocomposite for replacement of platinum in dye-sensitized solar cell

    OpenAIRE

    Shaista Rafique; Rehana Sharif; Imran Rashid; Sheeba Ghani

    2016-01-01

    This paper demonstrates the facile synthesis of high performance silver-polypyrrole-multiwall carbon nanotubes (Ag-PPy-FMWCNTS) nanocomposites via electrodeposition method on stainless steel substrate and its application as a low cost counter electrode (CE) for the precious platinum (Pt) free DSSC. The nanocomposites were characterized by variety of techniques such as Fourier transforms infrared (FTIR), X-ray diffraction, Scanning electron microscope (SEM), cyclic voltammetry (CV) and Four pr...

  6. Synthesis of carbon nanotubes bridging metal electrodes

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  7. Copolymers Based on Indole-6-Carboxylic Acid and 3,4-Ethylenedioxythiophene as Platinum Catalyst Support for Methanol Oxidation

    Directory of Open Access Journals (Sweden)

    Tzi-Yi Wu

    2015-10-01

    Full Text Available Indole-6-carboxylic acid (ICA and 3,4-ethylenedioxythiophene (EDOT are copolymerized electrochemically on a stainless steel (SS electrode to obtain poly(indole-6-carboxylic acid-co-3,4-ethylenedioxythiophenes (P(ICA-co-EDOTs. The morphology of P(ICA-co-EDOTs is checked using scanning electron microscopy (SEM, and the SEM images reveal that these films are composed of highly porous fibers when the feed molar ratio of ICA/EDOT is greater than 3/2. Platinum particles can be electrochemically deposited into the P(ICA-co-EDOTs and PICA films to obtain P(ICA-co-EDOTs-Pt and PICA-Pt composite electrodes, respectively. These composite electrodes are further characterized using X-ray photoelectron spectroscopy (XPS, SEM, X-ray diffraction analysis (XRD, and cyclic voltammetry (CV. The SEM result indicates that Pt particles disperse more uniformly into the highly porous P(ICA3-co-EDOT2 fibers (feed molar ratio of ICA/EDOT = 3/2. The P(ICA3-co-EDOT2-Pt nanocomposite electrode exhibited excellent catalytic activity for the electrooxidation of methanol in these electrodes, which reveals that P(ICA3-co-EDOT2-Pt nanocomposite electrodes are more promising for application in an electrocatalyst as a support material.

  8. Carbon nanomaterials as counter electrodes for dye solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Aitola, K.

    2012-05-15

    The dye solar cell (DSC) is an interesting emerging technology for photovoltaic conversion of solar electromagnetic energy to electrical energy. The DSC is based mainly on cheap starting materials and it can be manufactured by roll-to-roll deposition techniques on flexible substrates, which is considered as one option for cost-effective large-scale solar cell production. The most expensive component of the DSC is the transparent conductive oxide glass substrate, and considerable cost reductions can be achieved by changing it to e.g. a plastic substrate. Plastic substrates are very flexible, lightweight and transparent. The state of the art DSC catalyst is thermally deposited or sputtered platinum, but platinum is a rare and expensive metal. Carbon, on the other hand, is widely available and some of its nanomaterials conduct electricity and are catalytic toward the DSC counter electrode (CE) reduction reaction. In this work, carbon nanomaterials and their composites were studied as the DSC CE active material. The materials were random network single-walled carbon nanotube (SWCNT) film on glass and plastic substrate, vertically aligned multiwalled carbon nanotube 'forest' film on steel and quartz substrate and carbon nanoparticle composite film on indium tin oxidepolyethylene terephthalate (ITO-PET) substrate. After comparison of the materials, the SWCNT network film on PET was chosen as the main CE type of this study, since it offers superior conductivity, transparency and flexibility over the other carbon-based CEs, it is also the thinnest and contains only one active material component. When a 30 % transparent SWCNT network film on PET was tested as a DSC CE, it was found out that such a film is not catalytic and conductive enough for a full 1 sun illumination DSC device, but the film could be suitable for a indoor illumination level application. The catalytic properties of a 10 % transparent SWCNT film were improved by depositing conductive PEDOT

  9. Role of bonding mechanisms during transfer hydrogenation reaction on heterogeneous catalysts of platinum nanoparticles supported on zinc oxide nanorods

    Science.gov (United States)

    Al-Alawi, Reem A.; Laxman, Karthik; Dastgir, Sarim; Dutta, Joydeep

    2016-07-01

    For supported heterogeneous catalysis, the interface between a metal nanoparticle and the support plays an important role. In this work the dependency of the catalytic efficiency on the bonding chemistry of platinum nanoparticles supported on zinc oxide (ZnO) nanorods is studied. Platinum nanoparticles were deposited on ZnO nanorods (ZnO NR) using thermal and photochemical processes and the effects on the size, distribution, density and chemical state of the metal nanoparticles upon the catalytic activities are presented. The obtained results indicate that the bonding at Pt-ZnO interface depends on the deposition scheme which can be utilized to modulate the surface chemistry and thus the activity of the supported catalysts. Additionally, uniform distribution of metal on the catalyst support was observed to be more important than the loading density. It is also found that oxidized platinum Pt(IV) (platinum hydroxide) provided a more suitable surface for enhancing the transfer hydrogenation reaction of cyclohexanone with isopropanol compared to zero valent platinum. Photochemically synthesized ZnO supported nanocatalysts were efficient and potentially viable for upscaling to industrial applications.

  10. HVDC Ground Electrodes and Tectonic Setting

    Science.gov (United States)

    Freire, P. F.; Pereira, S. Y.

    2017-12-01

    Ground electrodes in HVDC transmission are huge grounding systems for the DC part of the converter substation, about 1 km wide, sized to inject in the ground DC currents up to 3.5 kA. This work presents an analysis of how the tectonic setting at converter substation location is determinant for the search of the best electrode location (Site Selection) and on its design and performance. It will briefly present the author experience on HVDC electrode design, summarized as follows: Itaipu - Foz do Iguaçu electrodes (transmitter side) located in the middle of Paraná Sedimentary Basin, and Ibiúna electrodes (receiving side) on the border of the basin, 6 km from the geological strike, where the crystalline basement outcrops in São Paulo state; Madeira River - North electrodes (transmitting side) located on the Northwest border of South Amazon Craton, where the crystalline basement is below a shallow sediments layer, and South electrodes (receiving side) located within Paraná Sedimentary Basin; Chile - electrodes located on the Andean forearc, where the Nazca Plate plunges under the South American Plate; Kenya - Ethiopia - electrodes located in the African Rift; Belo Monte - North electrodes (transmitter side) located within the Amazonian Sedimentary Basin, about 35 km of its South border, and South electrodes (receiving side) within Paraná Sedimentary Basin (bipole 1) and on crystalline metamorphic terrain "Brasília Belt" (bipole 2). This diversity of geological conditions results on ground electrodes of different topologies and dimensions, with quite different electrical and thermal performances. A brief study of the geology of the converter stations regions, the so-called Desktop Study, allows for the preview of several important parameters for the site selection and design of the electrodes, such as localization, type, size and estimate of the interference area, which are important predictors of the investment to be made and indications of the design to be

  11. Bioaccumulation of platinum group metals in dolphins, Stenella sp ...

    African Journals Online (AJOL)

    Platinum group metals (PGMs) concentrations were measured in the tissues= of dolphins (Stenella sp.) caught along the Ghanaian coastline. Tissues from specimens caught by fishermen from Dixcove, western Ghana, were analysed in 2006 for palladium (Pd), platinum (Pt) and rhodium (Rh) using the Neutron Activation ...

  12. Bimetallic alloy electrocatalysts with multilayered platinum-skin surfaces

    Science.gov (United States)

    Stamenkovic, Vojislav R.; Wang, Chao; Markovic, Nenad M.

    2016-01-26

    Compositions and methods of preparing a bimetallic alloy having enhanced electrocatalytic properties are provided. The composition comprises a PtNi substrate having a surface layer, a near-surface layer, and an inner layer, where the surface layer comprises a nickel-depleted composition, such that the surface layer comprises a platinum skin having at least one atomic layer of platinum.

  13. Preparation of platinum/iridium scanning probe microscopy tips

    DEFF Research Database (Denmark)

    Sørensen, Alexis Hammer; Hvid, U.; Mortensen, M.W.

    1999-01-01

    oxide layer. In order to explain the relatively high etching rates observed for the otherwise noble metal platinum we suggest that besides anodic corrosion of the platinum by the electrolyte containing chloride ions, a different etching mechanism causes a substantial increase of the etching rate...

  14. Atomically flat platinum films grown on synthetic mica

    Science.gov (United States)

    Tanaka, Hiroyuki; Taniguchi, Masateru

    2018-04-01

    Atomically flat platinum thin films were heteroepitaxially grown on synthetic fluorophlogopite mica [KMg3(AlSi3O10)F2] by van der Waals epitaxy. Platinum films deposited on a fluorophlogopite mica substrate by inductively coupled plasma-assisted sputtering with oxygen introduction on a synthetic mica substrate resulted in the growth of twin single-crystalline epitaxial Pt(111) films.

  15. Enzymatic recovery of platinum (IV) from industrial wastewater using ...

    African Journals Online (AJOL)

    highest hydrogen-dependent platinum (IV) reducing activity in the presence of hydrogenase and its physiological electron carrier, cytochrome c3. When the purified hydrogenase enzyme (with and without cytochrome c3) was used with the industrial effluent, containing 7.9 mg.l-1 platinum, only 10 – 15% recovery was noted ...

  16. High performance cermet electrodes

    Science.gov (United States)

    Isenberg, Arnold O.; Zymboly, Gregory E.

    1986-01-01

    Disclosed is a method of increasing the operating cell voltage of a solid oxide electrochemical cell having metal electrode particles in contact with an oxygen-transporting ceramic electrolyte. The metal electrode is heated with the cell, and oxygen is passed through the oxygen-transporting ceramic electrolyte to the surface of the metal electrode particles so that the metal electrode particles are oxidized to form a metal oxide layer between the metal electrode particles and the electrolyte. The metal oxide layer is then reduced to form porous metal between the metal electrode particles and the ceramic electrolyte.

  17. Effect of temperature on the electro-oxidation of ethanol on platinum

    OpenAIRE

    Camargo, Ana Paula M.; Previdello, Bruno A. F.; Varela, Hamilton; Gonzalez, Ernesto R.

    2010-01-01

    We present in this work an experimental investigation of the effect of temperature (from 25 to 180 ºC) in the electro-oxidation of ethanol on platinum in two different phosphoric acid concentrations. We observed that the onset potential for ethanol electro-oxidation shifts to lower values and the reaction rates increase as temperature is increased for both electrolytes. The results were rationalized in terms of the effect of temperature on the adsorption of reaction intermediates, poisons, an...

  18. The effects of thermal-neutron irradiation on platinum and dilute platinum-gold alloys

    International Nuclear Information System (INIS)

    Piani, C.S.B.

    1978-12-01

    The effect of varying defect concentrations on the recovery spectrum of thermal-neutron-irradiated pure platinum after isochronal anneals was investigated. The dose-independence of substages I(A), I(B) and I(C), and the dose dependence of substage I(D) and I(E), were observed to be in agreement with electron-irradiated studies. The 120 K substage in pure platinum was shown not to be due to interstitial-interstitial reactions, but could possibly be accounted for in terms of detrapping of interstitials from impurities or intrinsic immobile defects. The 360 K stage was shown to shift and was suppressed with increasing defect concentration. The possible conversion of the crowdion to a dumbbell near 160 K in Stage ll in platinum, as predicted by the two-interstitial model, was investigated by consideration of the initial slopes of the production curves between 80 K and 300 K. A minimum in these slopes was observed near 160 K and could be interpreted as due to the conversion of the highly mobile crowdion to an immobile dumbbell at this temperature. The influence of varying gold concentrations on the recovery spectrum of platinum was investigated in dilute platinum-gold alloys. The characteristics of several additional substages in Stage ll, due to the gold alloying were comparable to the results of electron-irradiation experiments. The observations made with regard to the impurity (gold) dependence of these substages could be interpreted in terms of the concentrations of the interstitials, vacancies and impurities present in the material. The interpretation of these substages was found to be consistent, if the recovery spectrum was investigated as a function of defect concentration [af

  19. Platinum supported on titanium–ruthenium oxide is a remarkably stable electrocatayst for hydrogen fuel cell vehicles

    Science.gov (United States)

    Parrondo, Javier; Han, Taehee; Niangar, Ellazar; Wang, Chunmei; Dale, Nilesh; Adjemian, Kev; Ramani, Vijay

    2014-01-01

    We report a unique and highly stable electrocatalyst—platinum (Pt) supported on titanium–ruthenium oxide (TRO)—for hydrogen fuel cell vehicles. The Pt/TRO electrocatalyst was exposed to stringent accelerated test protocols designed to induce degradation and failure mechanisms identical to those seen during extended normal operation of a fuel cell automobile—namely, support corrosion during vehicle startup and shutdown, and platinum dissolution during vehicle acceleration and deceleration. These experiments were performed both ex situ (on supports and catalysts deposited onto a glassy carbon rotating disk electrode) and in situ (in a membrane electrode assembly). The Pt/TRO was compared against a state-of-the-art benchmark catalyst—Pt supported on high surface-area carbon (Pt/HSAC). In ex situ tests, Pt/TRO lost only 18% of its initial oxygen reduction reaction mass activity and 3% of its oxygen reduction reaction-specific activity, whereas the corresponding losses for Pt/HSAC were 52% and 22%. In in situ-accelerated degradation tests performed on membrane electrode assemblies, the loss in cell voltage at 1 A · cm−2 at 100% RH was a negligible 15 mV for Pt/TRO, whereas the loss was too high to permit operation at 1 A · cm−2 for Pt/HSAC. We clearly show that electrocatalyst support corrosion induced during fuel cell startup and shutdown is a far more potent failure mode than platinum dissolution during fuel cell operation. Hence, we posit that the need for a highly stable support (such as TRO) is paramount. Finally, we demonstrate that the corrosion of carbon present in the gas diffusion layer of the fuel cell is only of minor concern. PMID:24367118

  20. Platinum supported on titanium-ruthenium oxide is a remarkably stable electrocatayst for hydrogen fuel cell vehicles.

    Science.gov (United States)

    Parrondo, Javier; Han, Taehee; Niangar, Ellazar; Wang, Chunmei; Dale, Nilesh; Adjemian, Kev; Ramani, Vijay

    2014-01-07

    We report a unique and highly stable electrocatalyst-platinum (Pt) supported on titanium-ruthenium oxide (TRO)-for hydrogen fuel cell vehicles. The Pt/TRO electrocatalyst was exposed to stringent accelerated test protocols designed to induce degradation and failure mechanisms identical to those seen during extended normal operation of a fuel cell automobile-namely, support corrosion during vehicle startup and shutdown, and platinum dissolution during vehicle acceleration and deceleration. These experiments were performed both ex situ (on supports and catalysts deposited onto a glassy carbon rotating disk electrode) and in situ (in a membrane electrode assembly). The Pt/TRO was compared against a state-of-the-art benchmark catalyst-Pt supported on high surface-area carbon (Pt/HSAC). In ex situ tests, Pt/TRO lost only 18% of its initial oxygen reduction reaction mass activity and 3% of its oxygen reduction reaction-specific activity, whereas the corresponding losses for Pt/HSAC were 52% and 22%. In in situ-accelerated degradation tests performed on membrane electrode assemblies, the loss in cell voltage at 1 A · cm(-2) at 100% RH was a negligible 15 mV for Pt/TRO, whereas the loss was too high to permit operation at 1 A · cm(-2) for Pt/HSAC. We clearly show that electrocatalyst support corrosion induced during fuel cell startup and shutdown is a far more potent failure mode than platinum dissolution during fuel cell operation. Hence, we posit that the need for a highly stable support (such as TRO) is paramount. Finally, we demonstrate that the corrosion of carbon present in the gas diffusion layer of the fuel cell is only of minor concern.

  1. Chiral discrimination in platinum anticancer drugs

    Czech Academy of Sciences Publication Activity Database

    Benedetti, M.; Malina, Jaroslav; Kašpárková, Jana; Brabec, Viktor; Natile, G.

    2002-01-01

    Roč. 110, Suppl. 5 (2002), s. 779-782 ISSN 0091-6765 R&D Projects: GA ČR GA301/00/0556; GA ČR GA305/02/1552; GA AV ČR IAA7004805; GA AV ČR IBS5004107; GA MŠk OC D20.001 Institutional research plan: CEZ:AV0Z5004920 Keywords : DNA * platinum * cancer Subject RIV: BO - Biophysics Impact factor: 3.452, year: 2002

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

    Science.gov (United States)

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

    2015-12-01

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

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

    Science.gov (United States)

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

    2015-12-01

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

  4. A NEW EMPIRICAL INVESTIGATION OF THE PLATINUM SPOT RETURNS

    Directory of Open Access Journals (Sweden)

    Simone Kruse

    2017-08-01

    Full Text Available The global platinum market has been in downturn and unstable for five consecutive years, and thus market participants are demanding effective quantitative risk management tools. Since platinum is so widely used and serves as an important investment vehicle, the importance of risk management of platinum spot returns cannot be understated. In this paper, we take advantage of a very popular econometric model, the generalized autoregressive conditional heteroscedasticity (GARCH model, for platinum returns. We received two important findings by using the conventional GARCH models in explain daily platinum spot returns. First, it is crucial to introduce heavy-tailed distribution to explain conditional heavy tails; and second, the NRIG distribution performs better than the most widely-used heavy-tailed distribution, the Student’s t distribution.

  5. CARBOXYLIC ACIDS ELECTROOXIDATION ON SHUNGITE ELECTRODE

    Directory of Open Access Journals (Sweden)

    Oleksandr Davydenko

    2017-03-01

    Full Text Available Purpose: This article discusses the electrochemical method of directional conversion of carboxylic acids, which are the most aggressive hydrocarbons oxidation products back into the corresponding hydrocarbons. Existing methods for the regeneration of waste petroleum oils have significant drawbacks, which include the formation of new hard-reclaimed waste and loss of a significant part of the oil during regeneration. Methods: Electrooxidation processes of carboxylic acid on various electrode materials: platinum, graphite and shungite anodes were studied. Results: Potentiostatic polarization curves with simultaneous measurement of near-electrode solution pH showed differences in the process on these anode materials: dimer yield for Kolbe is decreased under the transition from platinum to shungite. At potentials higher than 2.0 v, carboxylic acid has a higher adsorbability compared to water. Therefore Faraday’s side-process of water oxidation doesn’t almost occur, which contributes to high yield of expected product according to current. Electrolysis of carboxylic acids solutions under controlled potential (2.0 and 2.4 V and chromatographic analysis of the formed products showed that along with the dimeric structures formation for Kolbe reaction, the occurrence of a hydrocarbons mixture takes place, which may be the result of disproportionation of hydrocarbon radicals (alkane and alkene and hydrocarbons of isomeric structure, by further oxidation of the hydrocarbon radical to carbocation and its subsequent transformation into the corresponding saturated and unsaturated isomers. Such statement is not supported by conception of the process of one- and two-electron carboxylic acid oxidation. Discussion: General carboxylic acid oxidation scheme according to one-electron mechanism (dimerization and disproportionation of the radical and two-electron mechanism (formation and carbocation rearrangement is proposed. The formation of hydrocarbons under

  6. Doped graphene electrodes for organic solar cells

    International Nuclear Information System (INIS)

    Park, Hyesung; Kim, Ki Kang; Bulovic, Vladimir; Kong, Jing; Rowehl, Jill A

    2010-01-01

    In this work graphene sheets grown by chemical vapor deposition (CVD) with controlled numbers of layers were used as transparent electrodes in organic photovoltaic (OPV) devices. It was found that for devices with pristine graphene electrodes, the power conversion efficiency (PCE) is comparable to their counterparts with indium tin oxide (ITO) electrodes. Nevertheless, the chances for failure in OPVs with pristine graphene electrodes are higher than for those with ITO electrodes, due to the surface wetting challenge between the hole-transporting layer and the graphene electrodes. Various alternative routes were investigated and it was found that AuCl 3 doping on graphene can alter the graphene surface wetting properties such that a uniform coating of the hole-transporting layer can be achieved and device success rate can be increased. Furthermore, the doping both improves the conductivity and shifts the work function of the graphene electrode, resulting in improved overall PCE performance of the OPV devices. This work brings us one step further toward the future use of graphene transparent electrodes as a replacement for ITO.

  7. A Simple Hydrogen Electrode

    Science.gov (United States)

    Eggen, Per-Odd

    2009-01-01

    This article describes the construction of an inexpensive, robust, and simple hydrogen electrode, as well as the use of this electrode to measure "standard" potentials. In the experiment described here the students can measure the reduction potentials of metal-metal ion pairs directly, without using a secondary reference electrode. Measurements…

  8. The Composite Insertion Electrode

    DEFF Research Database (Denmark)

    Atlung, Sven; Zachau-Christiansen, Birgit; West, Keld

    1984-01-01

    The specific energy obtainable by discharge of porous insertion electrodes is limited by electrolyte depletion in thepores. This can be overcome using a solid ion conductor as electrolyte. The term "composite" is used to distinguishthese electrodes from porous electrodes with liquid electrolyte...

  9. Elaboration, physical and electrochemical characterizations of CO tolerant PEMFC anode materials. Study of platinum-molybdenum and platinum-tungsten alloys and composites; Elaborations et caracterisations electrochimiques et physiques de materiaux d'anode de PEMFC peu sensibles a l'empoisonnement par CO: etude d'alliages et de composites a base de platine-molybdene et de platine-tungstene

    Energy Technology Data Exchange (ETDEWEB)

    Peyrelade, E.

    2005-06-15

    PEMFC development is hindered by the CO poisoning ability of the anode platinum catalyst. It has been previously shown that the oxidation potential of carbon monoxide adsorbed on the platinum atoms can be lowered using specific Pt based catalysts, either metallic alloys or composites. The objective is then to realize a catalyst for which the CO oxidation is compatible with the working potential of a PEMFC anode. In our approach, to enhance the CO tolerance of platinum based catalyst supported on carbon, we studied platinum-tungsten and platinum-molybdenum alloys and platinum-metal oxide materials (Pt-WO{sub x} and Pt-MoO{sub x}). The platinum based alloys demonstrate a small effect of the second metal towards the oxidation of carbon monoxide. The platinum composites show a better tolerance to carbon monoxide. Electrochemical studies on both Pt-MoO{sub x} and Pt-WO{sub x} demonstrate the ability of the metal-oxides to promote the ability of Pt to oxidize CO at low potentials. However, chrono-amperometric tests reveal a bigger influence of the tungsten oxide. Complex chemistry reactions on the molybdenum oxide surface make it more difficult to observe. (author)

  10. Lithium alloy negative electrodes

    Science.gov (United States)

    Huggins, Robert A.

    The 1996 announcement by Fuji Photo Film of the development of lithium batteries containing convertible metal oxides has caused a great deal of renewed interest in lithium alloys as alternative materials for use in the negative electrode of rechargeable lithium cells. The earlier work on lithium alloys, both at elevated and ambient temperatures is briefly reviewed. Basic principles relating thermodynamics, phase diagrams and electrochemical properties under near-equilibrium conditions are discussed, with the Li-Sn system as an example. Second-phase nucleation, and its hindrance under dynamic conditions plays an important role in determining deviations from equilibrium behavior. Two general types of composite microstructure electrodes, those with a mixed-conducting matrix, and those with a solid electrolyte matrix, are discussed. The Li-Sn-Si system at elevated temperatures, and the Li-Sn-Cd at ambient temperatures are shown to be examples of mixed-conducting matrix microstructures. The convertible oxides are an example of the solid electrolyte matrix type. Although the reversible capacity can be very large in this case, the first cycle irreversible capacity required to convert the oxides to alloys may be a significant handicap.

  11. Fabrication of graphene–platinum nanocomposite for the direct electrochemistry and electrocatalysis of myoglobin

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Wei, E-mail: swyy26@hotmail.com [College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158 (China); College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Li, Linfang [College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Lei, Bingxin [College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158 (China); Li, Tongtong; Ju, Xiaomei; Wang, Xiuzheng; Li, Guangjiu [College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Sun, Zhenfan [College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158 (China)

    2013-05-01

    In this paper a platinum (Pt) nanoparticle decorated graphene (GR) nanosheet was synthesized and used for the investigation on direct electrochemistry of myoglobin (Mb). By integrating GR–Pt nanocomposite with Mb on the surface of carbon ionic liquid electrode (CILE), a new electrochemical biosensor was fabricated. UV-Vis absorption and FT-IR spectra indicated that Mb remained its native structure in the nanocomposite film. Electrochemical behaviors of Nafion/Mb–GR–Pt/CILE were investigated with a pair of well-defined redox peak appeared, which indicated that direct electron transfer of Mb was realized on the underlying electrode with the usage of the GR–Pt nanocomposite. The fabricated electrode showed good electrocatalytic activity to the reduction of trichloroacetic acid in the linear range from 0.9 to 9.0 mmol/L with the detection limit as 0.32 mmol/L (3σ), which showed potential application for fabricating novel electrochemical biosensors and bioelectronic devices. - Highlights: ► The GR–Pt nanocomposite was synthesized and employed for the fabrication of electrochemical biosensor. ► Direct electrochemistry of Mb in the nanocomposite was realized. ► The prepared biosensor exhibited excellent electrochemical response to the reduction of TCA.

  12. Fabrication of graphene-platinum nanocomposite for the direct electrochemistry and electrocatalysis of myoglobin.

    Science.gov (United States)

    Sun, Wei; Li, Linfang; Lei, Bingxin; Li, Tongtong; Ju, Xiaomei; Wang, Xiuzheng; Li, Guangjiu; Sun, Zhenfan

    2013-05-01

    In this paper a platinum (Pt) nanoparticle decorated graphene (GR) nanosheet was synthesized and used for the investigation on direct electrochemistry of myoglobin (Mb). By integrating GR-Pt nanocomposite with Mb on the surface of carbon ionic liquid electrode (CILE), a new electrochemical biosensor was fabricated. UV-Vis absorption and FT-IR spectra indicated that Mb remained its native structure in the nanocomposite film. Electrochemical behaviors of Nafion/Mb-GR-Pt/CILE were investigated with a pair of well-defined redox peak appeared, which indicated that direct electron transfer of Mb was realized on the underlying electrode with the usage of the GR-Pt nanocomposite. The fabricated electrode showed good electrocatalytic activity to the reduction of trichloroacetic acid in the linear range from 0.9 to 9.0 mmol/L with the detection limit as 0.32 mmol/L (3σ), which showed potential application for fabricating novel electrochemical biosensors and bioelectronic devices. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Long Life Nickel Electrodes for Nickel-Hydrogen Cells: Fiber Substrates Nickel Electrodes

    Science.gov (United States)

    Rogers, Howard H.

    2000-01-01

    Samples of nickel fiber mat electrodes were investigated over a wide range of fiber diameters, electrode thickness, porosity and active material loading levels. Thickness' were 0.040, 0.060 and 0.080 inches for the plaque: fiber diameters were primarily 2, 4, and 8 micron and porosity was 85, 90, and 95%. Capacities of 3.5 in. diameter electrodes were determined in the flooded condition with both 26 and 31% potassium hydroxide solution. These capacity tests indicated that the highest capacities per unit weight were obtained at the 90% porosity level with a 4 micron diameter fiber plaque. It appeared that the thinner electrodes had somewhat better performance, consistent with sintered electrode history. Limited testing with two-positive-electrode boiler plate cells was also carried out. Considerable difficulty with constructing the cells was encountered with short circuits the major problem. Nevertheless, four cells were tested. The cell with 95% porosity electrodes failed during conditioning cycling due to high voltage during charge. Discharge showed that this cell had lost nearly all of its capacity. The other three cells after 20 conditioning cycles showed capacities consistent with the flooded capacities of the electrodes. Positive electrodes made from fiber substrates may well show a weight advantage of standard sintered electrodes, but need considerably more work to prove this statement. A major problem to be investigated is the lower strength of the substrate compared to standard sintered electrodes. Problems with welding of leads were significant and implications that the electrodes would expand more than sintered electrodes need to be investigated. Loading levels were lower than had been expected based on sintered electrode experiences and the lower loading led to lower capacity values. However, lower loading causes less expansion and contraction during cycling so that stress on the substrate is reduced.

  14. Structure, activity, and stability of platinum alloys as catalysts for the oxygen reduction reaction

    DEFF Research Database (Denmark)

    Vej-Hansen, Ulrik Grønbjerg

    In this thesis I present our work on theoretical modelling of platinum alloys as catalysts for the Oxygen Reduction Reaction (ORR). The losses associated with the kinetics of the ORR is the main bottleneck in low-temperature fuel cells for transport applications, and more active catalysts...... are essential for wide-spread use of this technology. platinum alloys have shown great promise as more active catalysts, which are still stable under reaction conditions. We have investigated these systems on multiple scales, using either Density Functional Theory (DFT) or Effective Medium Theory (EMT......), depending on the length and time scales involved. Using DFT, we show how diffusion barriers in transition metal alloys in the L12 structure depend on the alloying energy, supporting the assumption that an intrinsically more stable alloy is also more stable towards diffusion-related degradation...

  15. Influence Use of NGK Platinum C 7hvx Sparkplug toward Performance and Emision Gas of Four Stroke Motorcycle 110 Cc

    Directory of Open Access Journals (Sweden)

    Daud Pulo Mangesa

    2012-11-01

    Full Text Available Spark plug is a tool for producing an electric fire arc which has influences in process of combustion perfection, in internalcombustion engines. Spark plugs with electrode tip made of platinum, have good conducting character. The spark plugs areclaimed by their manufactures, are able to improve engines performance and able to reduce waste gases emission rate. Targets ofthis research is comparison C 7HSA Standard NGK Spark plug with NGK Platinum C 7HVX spark plug, in engine performance (power, efficiency, fuel consumptions and in waste gases emission rate ( CO rate level at engine rotation 2500 rpm, 3000 rpm,and 3500 rpm. 1 kg, 1,5 kg, 2 kg loads were used in waste gases emission rate examinations and fuel consumptions examinations.Data-processing methods were used in this research were descriptive analysis, correlation analysis and regression linieranalysis. Results of this research showed that by using NGK Platinum C 7HVX spark plug will be able to improve engineperformance ( power, efficiency, fuel consumptions and gases emission rate ( CO rate level if we compare with engine whichusing C 7HSA Standard NGK Spark plug.

  16. A Multi-Parametric Device with Innovative Solid Electrodes for Long-Term Monitoring of pH, Redox-Potential and Conductivity in a Nuclear Waste Repository

    Directory of Open Access Journals (Sweden)

    Jordan Daoudi

    2017-06-01

    Full Text Available We present an innovative electrochemical probe for the monitoring of pH, redox potential and conductivity in near-field rocks of deep geological radioactive waste repositories. The probe is composed of a monocrystalline antimony electrode for pH sensing, four AgCl/Ag-based reference or Cl− selective electrodes, one Ag2S/Ag-based reference or S2− selective electrode, as well as four platinum electrodes, a gold electrode and a glassy-carbon electrode for redox potential measurements. Galvanostatic electrochemistry impedance spectroscopy using AgCl/Ag-based and platinum electrodes measure conductivity. The use of such a multi-parameter probe provides redundant information, based as it is on the simultaneous behaviour under identical conditions of different electrodes of the same material, as well as on that of electrodes made of different materials. This identifies the changes in physical and chemical parameters in a solution, as well as the redox reactions controlling the measured potential, both in the solution and/or at the electrode/solution interface. Understanding the electrochemical behaviour of selected materials thus is a key point of our research, as provides the basis for constructing the abacuses needed for developing robust and reliable field sensors.

  17. A Multi-Parametric Device with Innovative Solid Electrodes for Long-Term Monitoring of pH, Redox-Potential and Conductivity in a Nuclear Waste Repository.

    Science.gov (United States)

    Daoudi, Jordan; Betelu, Stephanie; Tzedakis, Theodore; Bertrand, Johan; Ignatiadis, Ioannis

    2017-06-13

    We present an innovative electrochemical probe for the monitoring of pH, redox potential and conductivity in near-field rocks of deep geological radioactive waste repositories. The probe is composed of a monocrystalline antimony electrode for pH sensing, four AgCl/Ag-based reference or Cl - selective electrodes, one Ag₂S/Ag-based reference or S 2- selective electrode, as well as four platinum electrodes, a gold electrode and a glassy-carbon electrode for redox potential measurements. Galvanostatic electrochemistry impedance spectroscopy using AgCl/Ag-based and platinum electrodes measure conductivity. The use of such a multi-parameter probe provides redundant information, based as it is on the simultaneous behaviour under identical conditions of different electrodes of the same material, as well as on that of electrodes made of different materials. This identifies the changes in physical and chemical parameters in a solution, as well as the redox reactions controlling the measured potential, both in the solution and/or at the electrode/solution interface. Understanding the electrochemical behaviour of selected materials thus is a key point of our research, as provides the basis for constructing the abacuses needed for developing robust and reliable field sensors.

  18. Study of the electrocatalytic oxidation of Ethanol over platinum in medium acid

    International Nuclear Information System (INIS)

    Hoyos, Bibian; Gonzalez, Javier; Sanchez, Carlos

    2002-01-01

    Electro-catalytic oxidation of ethanol on platinum surfaces in sulfuric acid solutions at different temperatures and concentrations was studied by cyclic voltammetry. The results shown that there is ethanol adsorption at potentials below 0.4V (vs. RHE) with electrode coverage fraction for residues of 0.3 or less. There are also, two irreversible oxidation reactions. Former reaction seems be catalyzed by Pt(OH) species with electronic charge transfer control and the second reaction seems be catalyzed by Pt(OH) 4 with diffusion control while Pt(OH) 2 does not have catalytic activity. The activity and selectivity for total oxidation increases with ethanol concentration and temperature. Finally, a reaction mechanism, which explains the obtained data, is proposed

  19. Copper (II) complexes of bidentate ligands exhibit potent anti-cancer activity regardless of platinum sensitivity status.

    Science.gov (United States)

    Wehbe, Mohamed; Lo, Cody; Leung, Ada W Y; Dragowska, Wieslawa H; Ryan, Gemma M; Bally, Marcel B

    2017-12-01

    Insensitivity to platinum, either through inherent or acquired resistance, is a major clinical problem in the treatment of many solid tumors. Here, we explored the therapeutic potential of diethyldithiocarbamate (DDC), pyrithione (Pyr), plumbagin (Plum), 8-hydroxyquinoline (8-HQ), clioquinol (CQ) copper complexes in a panel of cancer cell lines that differ in their sensitivity to platins (cisplatin/carboplatin) using a high-content imaging system. Our data suggest that the copper complexes were effective against both platinum sensitive (IC 50  ~ 1 μM platinum) and insensitive (IC 50  > 5 μM platinum) cell lines. Furthermore, copper complexes of DDC, Pyr and 8-HQ had greater therapeutic activity compared to the copper-free ligands in all cell lines; whereas the copper-dependent activities of Plum and CQ were cell-line specific. Four of the copper complexes (Cu(DDC) 2 , Cu(Pyr) 2 , Cu(Plum) 2 and Cu(8-HQ) 2 ) showed IC 50 values less than that of cisplatin in all tested cell lines. The complex copper DDC (Cu(DDC) 2 ) was selected for in vivo evaluation due to its low nano-molar range activity in vitro and the availability of an injectable liposomal formulation. Liposomal (Cu(DDC) 2 ) was tested in a fast-growing platinum-resistant A2780-CP ovarian xenograft model and was found to achieve a statistically significant reduction (50%; p < 0.05) in tumour size. This work supports the potential use of copper-based therapeutics to treat cancers that are insensitive to platinum drugs.

  20. The RSC Faraday prize lecture of 1989 on platinum.

    Science.gov (United States)

    Thomas, John Meurig

    2017-08-25

    In 1861, Michael Faraday gave one of his last Friday Evening Discourses at the Royal Institution of Great Britain, London, on platinum, which he described as "this beautiful, magnificent and valuable metal". More than a hundred and twenty years later (in 1989), the author re-enacted, at the Royal Institution, many of the demonstrations that Faraday carried out in his memorable Discourse. This article outlines many of Faraday's views on, and experiments with, platinum. It also describes the continuing importance and utilization of platinum, both as perceived in 1989 and from present perspectives.

  1. Multi electrode semiconductors detectors

    CERN Document Server

    Amendolia, S R; Bertolucci, Ennio; Bosisio, L; Bradaschia, C; Budinich, M; Fidecaro, F; Foà, L; Focardi, E; Giazotto, A; Giorgi, M A; Marrocchesi, P S; Menzione, A; Ristori, L; Rolandi, Luigi; Scribano, A; Stefanini, A; Vincelli, M L

    1981-01-01

    Detectors with very high space resolution have been built in this laboratory and tested at CERN in order to investigate their possible use in high energy physics experiments. These detectors consist of thin layers of silicon crystals acting as ionization chambers. Thin electrodes, structured in strips or in more fancy shapes are applied to their surfaces by metal coating. The space resolution which could be reached is of the order of a few microns. An interesting feature of these solid state detectors is that they can work under very high or low external pressure or at very low temperature. The use of these detectors would strongly reduce the dimensions and the cost of high energy experiments. (3 refs).

  2. Multi electrode semiconductor detectors

    International Nuclear Information System (INIS)

    Amendolia, S.R.; Batignani, G.; Bertolucci, E.; Bosisio, L.; Budinich, M.; Bradaschia, C.; Fidecaro, F.; Foa, L.; Focardi, E.; Giazotto, A.; Giorgi, M.A.; Marrocchesi, P.S.; Menzione, A.; Ristori, L.; Rolandi, L.; Scribano, A.; Stefanini, A.; Vincelli, M.L.

    1981-01-01

    Detectors with very high space resolution have been built in the laboratory and tested at CERN in order to investigate their possible use in high energy physics experiments. These detectors consist of thin layers of silicon crystals acting as ionization chambers. Thin electrodes, structured in strips or in more fancy shapes are applied to their surfaces by metal coating. The space resolution which could be reached is of the order of a few microns. An interesting feature of these solid state detectors is that they can work under very high or low external pressure or at very low temperature. The use of these detectors would strongly reduce the dimensions and the cost of high energy experiments. (Auth.)

  3. Insulating electrodes: a review on biopotential front ends for dielectric skin–electrode interfaces

    International Nuclear Information System (INIS)

    Spinelli, Enrique; Haberman, Marcelo

    2010-01-01

    Insulating electrodes, also known as capacitive electrodes, allow acquiring biopotentials without galvanic contact with the body. They operate with displacement currents instead of real charge currents, and the electrolytic electrode–skin interface is replaced by a dielectric film. The use of insulating electrodes is not the end of electrode interface problems but the beginning of new ones: coupling capacitances are of the order of pF calling for ultra-high input impedance amplifiers and careful biasing, guarding and shielding techniques. In this work, the general requirements of front ends for capacitive electrodes are presented and the different contributions to the overall noise are discussed and estimated. This analysis yields that noise bounds depend on features of the available devices as current and voltage noise, but the final noise level also depends on parasitic capacitances, requiring a careful shield and printed circuit design. When the dielectric layer is placed on the skin, the present-day amplifiers allow achieving noise levels similar to those provided by wet electrodes. Furthermore, capacitive electrode technology allows acquiring high quality ECG signals through thin clothes. A prototype front end for capacitive electrodes was built and tested. ECG signals were acquired with these electrodes in direct contact with the skin and also through cotton clothes 350 µm thick. They were compared with simultaneously acquired signals by means of wet electrodes and no significant differences were observed between both output signals

  4. Electrocatalysis of oxygen electrode reactions by some perovskite oxides based on lanthanum manganate

    International Nuclear Information System (INIS)

    Raj, I.A.; Rao, K.V.; Venkatesan, V.K.

    1984-01-01

    In recent years, several electrocatalyst materials based on platinum, silver, tungsten bronzes, spinels, metal chelates, etc., have been studied for use as oxygen diffusion electrodes in alkaline fuel cells, secondary metal-air batteries, and water electrolyzers. However, virtually all catalysts of commercial importance are semiconducting transition metal oxides. The various oxide catalysts that have been studied can be grouped under mixed oxides, spinels, and perovskites

  5. Catalytic polarographic currents of platinum metal complexes and their application to determination of trace concentrations of the elements

    International Nuclear Information System (INIS)

    Ezerskaya, N.A.; Kiseleva, I.N.

    1984-01-01

    Several types of catalytic electrode processes with the participation of platinum metal complexes and used for the determination of the element microconcentrations have been considered in the review. It is pointed out that to measure catalytic currents of hydrogen solutions nitroso compounds, which are prepared by heating chloride complexes of Ru(3) and (4) with NaNO 2 are used. The method is applicable for ruthenium determination in commercial nitric acid solutions. Ru determination in solution of ruthenium (4) dimeric chloride complex on graphite electrode, using catalytic currents of hydrogen, surpasses in sensitivity the determination of the element, using the method of inversion voltammetry. Certain other complexes of Ru and determination methods of ruthenium in them are considered. Hydrogen catalytic currents in the complexes solutions with organic ligands are the most perspective for analysis

  6. Investigating the effects of proton exchange membrane fuel cell conditions on carbon supported platinum electrocatalyst composition and performance

    Energy Technology Data Exchange (ETDEWEB)

    Patel, Anant; Artyushkova, Kateryna; Atanassov, Plamen; Colbow, Vesna; Dutta, Monica; Harvey, Davie; Wessel, Silvia

    2011-12-01

    Changes that carbon-supported platinum electrocatalysts undergo in a proton exchange membrane fuel cell environment were simulated by ex situ heat treatment of catalyst powder samples at 150 C and 100% relative humidity. In order to study modifications that are introduced to chemistry, morphology, and performance of electrocatalysts, XPS, HREELS and three-electrode rotating disk electrode experiments were performed. Before heat treatment, graphitic content varied by 20% among samples with different types of carbon supports, with distinct differences between bulk and surface compositions within each sample. Following the aging protocol, the bulk and surface chemistry of the samples were similar, with graphite content increasing or remaining constant and Pt-carbide decreasing for all samples. From the correlation of changes in chemical composition and losses in performance of the electrocatalysts, we conclude that relative distribution of Pt particles on graphitic and amorphous carbon is as important for electrocatalytic activity as the absolute amount of graphitic carbon present

  7. Investigating the effects of proton exchange membrane fuel cell conditions on carbon supported platinum electrocatalyst composition and performance

    Energy Technology Data Exchange (ETDEWEB)

    A. Patel; K. Artyushkova; P. Atanassov; V. Colbow; M. Dutta; D. Harvey; S. Wessel

    2012-04-30

    Changes that carbon-supported platinum electrocatalysts undergo in a proton exchange membrane fuel cell environment were simulated by ex situ heat treatment of catalyst powder samples at 150 C and 100% relative humidity. In order to study modifications that are introduced to chemistry, morphology, and performance of electrocatalysts, XPS, HREELS and three-electrode rotating disk electrode experiments were performed. Before heat treatment, graphitic content varied by 20% among samples with different types of carbon supports, with distinct differences between bulk and surface compositions within each sample. Following the aging protocol, the bulk and surface chemistry of the samples were similar, with graphite content increasing or remaining constant and Pt-carbide decreasing for all samples. From the correlation of changes in chemical composition and losses in performance of the electrocatalysts, we conclude that relative distribution of Pt particles on graphitic and amorphous carbon is as important for electrocatalytic activity as the absolute amount of graphitic carbon present

  8. Flexible multichannel vagus nerve electrode for stimulation and recording for heart failure treatment.

    Science.gov (United States)

    Xue, Ning; Martinez, Ignacio Delgado; Sun, Jianhai; Cheng, Yuhua; Liu, Chunxiu

    2018-07-30

    Vagus nerve stimulation is an emerging bioelectronic medicine to modulate cardiac function, as the nerve provides parasympathetic innervation to the heart. In this study, we developed a polyimide based 2D cuff electrode to wrap around on the vagus nerve. Thanks to the tiny size and bendable protruding structure of the contact tips of the device, the electrode sites are able to flexibly bend to touch the nerve, selectively record and stimulate the vagus nerve. Gold, platinum and platinum black materials were chosen to compose the electrodes for nerve stimulation and recording, respectively. Since the platinum black has ~30 times larger charge delivery capacity (CDC) than gold, Pt black electrode is used for nerve stimulation. The electrochemical impedance spectroscopy and cyclic voltammetry measurement of the three materials were conducted in vitro, revealing the results of 405 kΩ, 41 kΩ, 10.5 kΩ, @1 kHz and 0.81 mC/cm 2 , 4.26 mC/cm 2 , 25.5 mC/cm 2 , respectively (n = 3). The cuff electrodes were implanted into the right-sided vagus nerve of rats for in vivo experiment. Biphasic current configuration was implemented for nerve stimulation with frequency of 10 Hz, pulse during of 300 μs and various currents stimulus. The result shows the heart beat frequency drops up to 36% during the stimulation and was able to return the regular frequency as stimulation was removed. Subsequently, the vagus nerve signals were recorded with the four channel cuff electrodes. The magnitude of the compound nerve action potentials (CNAPs) is ~10 μV and the signal to noise ratio (SNR) is ~20. Copyright © 2018 Elsevier B.V. All rights reserved.

  9. Emerging Novel Metal Electrodes for Photovoltaic Applications.

    Science.gov (United States)

    Lu, Haifei; Ren, Xingang; Ouyang, Dan; Choy, Wallace C H

    2018-04-01

    Emerging novel metal electrodes not only serve as the collector of free charge carriers, but also function as light trapping designs in photovoltaics. As a potential alternative to commercial indium tin oxide, transparent electrodes composed of metal nanowire, metal mesh, and ultrathin metal film are intensively investigated and developed for achieving high optical transmittance and electrical conductivity. Moreover, light trapping designs via patterning of the back thick metal electrode into different nanostructures, which can deliver a considerable efficiency improvement of photovoltaic devices, contribute by the plasmon-enhanced light-mattering interactions. Therefore, here the recent works of metal-based transparent electrodes and patterned back electrodes in photovoltaics are reviewed, which may push the future development of this exciting field. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Carbon monoxide oxidation on Pt single crystal electrodes: understanding the catalysis for low temperature fuel cells.

    Science.gov (United States)

    García, Gonzalo; Koper, Marc T M

    2011-08-01

    Herein the general concepts of fuel cells are discussed, with special attention to low temperature fuel cells working in alkaline media. Alkaline low temperature fuel cells could well be one of the energy sources in the next future. This technology has the potential to provide power to portable devices, transportation and stationary sectors. With the aim to solve the principal catalytic problems at the anode of low temperature fuel cells, a fundamental study of the mechanism and kinetics of carbon monoxide as well as water dissociation on stepped platinum surfaces in alkaline medium is discussed and compared with those in acidic media. Furthermore, cations involved as promoters for catalytic surface reactions are also considered. Therefore, the aim of the present work is not only to provide the new fundamental advances in the electrocatalysis field, but also to understand the reactions occurring at fuel cell catalysts, which may help to improve the fabrication of novel electrodes in order to enhance the performance and to decrease the cost of low temperature fuel cells. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Platinum dendritic nanoparticles with magnetic behavior

    Energy Technology Data Exchange (ETDEWEB)

    Li, Wenxian, E-mail: wl240@uowmail.edu.au [Institute for Superconducting and Electronic Materials, University of Wollongong, NSW 2522 (Australia); Solar Energy Technologies, School of Computing, Engineering, and Mathematics, University of Western Sydney, Penrith NSW 2751 (Australia); Sun, Ziqi; Nevirkovets, Ivan P.; Dou, Shi-Xue [Institute for Superconducting and Electronic Materials, University of Wollongong, NSW 2522 (Australia); Tian, Dongliang [Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of the Ministry of Education, School of Chemistry and the Environment, Beihang University, Beijing 100191 (China)

    2014-07-21

    Magnetic nanoparticles have attracted increasing attention for biomedical applications in magnetic resonance imaging, high frequency magnetic field hyperthermia therapies, and magnetic-field-gradient-targeted drug delivery. In this study, three-dimensional (3D) platinum nanostructures with large surface area that features magnetic behavior have been demonstrated. The well-developed 3D nanodendrites consist of plentiful interconnected nano-arms ∼4 nm in size. The magnetic behavior of the 3D dendritic Pt nanoparticles is contributed by the localization of surface electrons due to strongly bonded oxygen/Pluronic F127 and the local magnetic moment induced by oxygen vacancies on the neighboring Pt and O atoms. The magnetization of the nanoparticles exhibits a mixed paramagnetic and ferromagnetic state, originating from the core and surface, respectively. The 3D nanodendrite structure is suitable for surface modification and high amounts of drug loading if the transition temperature was enhanced to room temperature properly.

  12. Superconductivity observed in platinum-silicon interface

    Energy Technology Data Exchange (ETDEWEB)

    Kuo, Pai-Chia, E-mail: paichia@phys.sinica.edu.tw [Research Program on Nanoscience and Nanotechnology, Academia Sinica, Taipei 11529, Taiwan (China); Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (China); Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Chen, Chun-Wei [Department of Materials Science and Engineering, National Taiwan University, Taipei 10617, Taiwan (China); Lee, Ku-Pin; Shiue, Jessie, E-mail: yshiue@phys.sinica.edu.tw [Research Program on Nanoscience and Nanotechnology, Academia Sinica, Taipei 11529, Taiwan (China); Institute of Physics, Academia Sinica, Taipei 11529, Taiwan (China)

    2014-05-26

    We report the discovery of superconductivity with an onset temperature of ∼0.6 K in a platinum-silicon interface. The interface was formed by using a unique focused ion beam sputtering micro-deposition method in which the energies of most sputtered Pt atoms are ∼2.5 eV. Structural and elemental analysis by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy reveal a ∼ 7 nm interface layer with abundant Pt, which is the layer likely responsible for the superconducting transport behavior. Similar transport behavior was also observed in a gold-silicon interface prepared by the same technique, indicating the possible generality of this phenomenon.

  13. A platinum in-core flux detector

    International Nuclear Information System (INIS)

    Shields, R.B.

    1976-01-01

    The performance is described of a platinum emitter self-powered detector having the following parameters: emitter diameter 0.51 mm, Inconel 600 collector of 1.5 mm outer diameter and 0.25 mm wall thickness, compacted powder MgO insulant, thermal neutron flux 10 14 n.cm -2 .s -1 and gamma radiation dose rate 1.2 x 10 8 rad.h -1 . The advantage of the detector is its sensitivity to both neutrons and gamma radiation. A comparison is made with other types of detectors using Ce, Ta, Os, Rh, V, Co, Zr as emitters, especially in relation to the emitter response time to neutrons or gammas, the output signal amplitude, sensitivity, and the emitter half-life. Extensive tests of the detectors proceeded for two years on the NRU and CANDU-BLW reactors in Gentilly, Canada. (J.B.)

  14. Platinum dendritic nanoparticles with magnetic behavior

    International Nuclear Information System (INIS)

    Li, Wenxian; Sun, Ziqi; Nevirkovets, Ivan P.; Dou, Shi-Xue; Tian, Dongliang

    2014-01-01

    Magnetic nanoparticles have attracted increasing attention for biomedical applications in magnetic resonance imaging, high frequency magnetic field hyperthermia therapies, and magnetic-field-gradient-targeted drug delivery. In this study, three-dimensional (3D) platinum nanostructures with large surface area that features magnetic behavior have been demonstrated. The well-developed 3D nanodendrites consist of plentiful interconnected nano-arms ∼4 nm in size. The magnetic behavior of the 3D dendritic Pt nanoparticles is contributed by the localization of surface electrons due to strongly bonded oxygen/Pluronic F127 and the local magnetic moment induced by oxygen vacancies on the neighboring Pt and O atoms. The magnetization of the nanoparticles exhibits a mixed paramagnetic and ferromagnetic state, originating from the core and surface, respectively. The 3D nanodendrite structure is suitable for surface modification and high amounts of drug loading if the transition temperature was enhanced to room temperature properly.

  15. Electrochemical Oxidation of Glycerol Using Gold Electrode

    International Nuclear Information System (INIS)

    Mohamed Rozali Othman; Amirah Ahmad

    2015-01-01

    Cyclic voltammetry, potential linear V and chronocuolometry methods were carried out to gain electrochemical behavior of glycerol at a gold electrode. Potassium hydroxide and sulfuric acid were chosen to be the electrolyte for the electro-oxidation of this organic compound. Besides gold plate electrode, gold composite electrode (Au-PVC) was also used as the working electrode. The Au-PVC composite electrode was characterized by Scanning Electron Microscopy (SEM) to determine its morphological aspects before and after used in electrochemical oxidation of glycerol. In alkaline solution, the adsorption of hydroxide species onto the surface of both gold plate and composite Au-PVC electrodes occurs at potential around 500 mV vs SCE. However, at gold plate electrode, there was a small, broad peak before the drastic escalation of current densities which indicates the charge transfer of the chemisorbed OH - anion. In acidic media, the gold oxide was formed after potential 1.0 V. From the cyclic voltammogram glycerol undergo oxidation twice in potassium hydroxide at gold plate and Au-PVC composite electrodes, while in sulfuric acid, oxidation reaction happened once for glycerol on the gold plate electrode. Overall, electrochemical oxidation of glycerol was more effective in alkaline media. Tafel graph which plotted from potential linear V method shows that Au-PVC composite electrode is better than gold plate electrode for the electro-oxidation of glycerol in alkaline solution. Electrochemical oxidation of glycerol products as analyzed by Gas Chromatography-Mass Spectrometry (GC-MS) produced several carboxylic acids and phenolic compounds. (author)

  16. Calibration of antimony-based electrode for ph monitoring into underground components of nuclear repositories

    International Nuclear Information System (INIS)

    Betelu, S.; Ignatiadis, I.

    2012-01-01

    unchanged with regard to pH variations, considering the RSD based on reproducibility. Whatever the ligand, no complex has competed with both the antimony hydrolysis and the oxygen depletion. The Sb electrode potential (E Sb ) varied linearly as a function of pH. Electrodes exhibit almost ideal Nernstian response. There was sufficient oxidation at the metal surface to ensure the equilibration conditions. Moreover, E Sb was somewhat affected by hysteresis. The potential of the platinum electrode (E Pt ) under atmospheric oxygen saturation is fixed by the O 2 /H 2 O redox couple. Under these conditions, EPt is governed by the PtO/Pt couple via PtO + 2H + + 2e - ↔ Pt + H 2 O with E PtO/Pt (mV/NHE) = 60.5 pH + 902. At the same pH and under aerobic conditions, a difference of about 700 mV (pH 0) is observed between EPt and E Sb . This difference is reduced to about 330 mV under anoxic conditions where O 2 /H 2 O is the predominant redox couple with a very low quantity of oxygen. Moreover, the slope of the E Sb -pH line remains the same regardless of the medium, which is very important, while the intercept giving the potential at pH = 0 differs by about 50 mV. This shows the dependence, although weak, of the Sb-based electrodes on the O 2 /H 2 O redox couple in the solution. This work provides information concerning the simultaneous but different behavior of two different electrodes under identical conditions and the same reference electrode. Knowledge of their electrochemical curves will allow us to draw potential-pH diagrams when observing and monitoring pH in the underground components of radioactive waste repositories where reference electrodes will not be used. Mono-crystalline Sb electrode appears to be appropriate for accurate measurements of pH in these conditions. Work is in progress to demonstrate the robustness of the Sb-electrode into COx over a long period

  17. Fabrication of GNPs/CDSH-Fc/nafion modified electrode for the detection of dopamine in the presence of ascorbic acid

    International Nuclear Information System (INIS)

    Chen Ming; Wei Xiujuan; Qian Hui; Diao Guowang

    2011-01-01

    A novel dopamine sensor was fabricated by forming the inclusion complex between mono-6-thio-β-cyclodextrin (CD-SH) and ferrocene (Fc) functionalized gold nanoparticles (GNPs) films on a platinum electrode. The properties of the GNPs/CDSH-Fc nanocomposite were characterized by Fourier transform infrared spectra, UV-visible absorption spectroscopy, transmission electron microscopy and cyclic voltammetry. The electrochemistry of dopamine (DA) was investigated by cyclic voltammetry (CV) and differential pulse voltammograms (DPV). The electrooxidation of dopamine could be catalyzed by Fc/Fc + couple as a mediator and had a higher electrochemical response due to the unique performance of GNPs/CDSH-Fc. The anodic peaks of DA and ascorbic acid (AA) in their mixture can be well separated by the prepared electrode. Under optimum conditions linear calibration graphs were obtained over the DA concentration range 2.0 x 10 -6 to 5.0 x 10 -5 M with a correlation coefficient of 0.998 and a detection limit of 9.0 x 10 -8 M (S/N = 3). The modified electrode had been effectively applied for the assay of DA in dopamine hydrochloride injections. This work provides a simple and easy approach to selectively detect DA in the presence of AA. - Research highlights: → The sensor of DA was constructed by using GNPs/CDSH-Fc as the building block. → Inclusion complex on the surface of GNPs decreased the leakage of mediator. → The electro-oxidation of DA could be catalyzed by Fc/Fc + couple as a mediator. → This work provides a simple approach to selectively detect DA in the presence of AA.

  18. 3D finite element modeling of epiretinal stimulation: Impact of prosthetic electrode size and distance from the retina.

    Science.gov (United States)

    Sui, Xiaohong; Huang, Yu; Feng, Fuchen; Huang, Chenhui; Chan, Leanne Lai Hang; Wang, Guoxing

    2015-05-01

    A novel 3-dimensional (3D) finite element model was established to systematically investigate the impact of the diameter (Φ) of disc electrodes and the electrode-to-retina distance on the effectiveness of stimulation. The 3D finite element model was established based on a disc platinum stimulating electrode and a 6-layered retinal structure. The ground electrode was placed in the extraocular space in direct attachment with sclera and treated as a distant return electrode. An established criterion of electric-field strength of 1000 Vm-1 was adopted as the activation threshold for RGCs. The threshold current (TC) increased linearly with increasing Φ and electrode-to-retina distance and remained almost unchanged with further increases in diameter. However, the threshold charge density (TCD) increased dramatically with decreasing electrode diameter. TCD exceeded the electrode safety limit for an electrode diameter of 50 µm at an electrode-to-retina distance of 50 to 200 μm. The electric field distributions illustrated that smaller electrode diameters and shorter electrode-to-retina distances were preferred due to more localized excitation of RGC area under stimulation of different threshold currents in terms of varied electrode size and electrode-to-retina distances. Under the condition of same-amplitude current stimulation, a large electrode exhibited an improved potential spatial selectivity at large electrode-to-retina distances. Modeling results were consistent with those reported in animal electrophysiological experiments and clinical trials, validating the 3D finite element model of epiretinal stimulation. The computational model proved to be useful in optimizing the design of an epiretinal stimulating electrode for prosthesis.

  19. Silver-coated ion exchange membrane electrode applied to electrochemical reduction of carbon dioxide

    International Nuclear Information System (INIS)

    Hori, Y.; Ito, H.; Okano, K.; Nagasu, K.; Sato, S.

    2003-01-01

    Silver-coated ion exchange membrane electrodes (solid polymer electrolyte, SPE) were prepared by electroless deposition of silver onto ion exchange membranes. The SPE electrodes were used for carbon dioxide (CO 2 ) reduction with 0.2 M K 2 SO 4 as the electrolyte with a platinum plate (Pt) for the counterelectrode. In an SPE electrode system prepared from a cation exchange membrane (CEM), the surface of the SPE was partly ruptured during CO 2 reduction, and the reaction was rapidly suppressed. SPE electrodes made of an anion exchange membrane (SPE/AEM) sustained reduction of CO 2 to CO for more than 2 h, whereas, the electrode potential shifted negatively during the electrolysis. The reaction is controlled by the diffusion of CO 2 through the metal layer of the SPE electrode at high current density. Ultrasonic radiation, applied to the preparation of SPE/AEM, was effective to improve the electrode properties, enhancing the electrolysis current of CO 2 reduction. Observation by a scanning electron microscope (SEM) showed that the electrode metal layer became more porous by the ultrasonic radiation treatment. The partial current density of CO 2 reduction by SPE/AEM amounted to 60 mA cm -2 , i.e. three times the upper limit of the conventional electrolysis by a plate electrode. Application of SPE device may contribute to an advancement of CO 2 fixation at ambient temperature and pressure

  20. ETEM observation of Pt/C electrode catalysts in a moisturized cathode atmosphere

    International Nuclear Information System (INIS)

    Yoshida, K; Zhang, X; Tanaka, N; Boyes, E D; Gai, P L

    2014-01-01

    There have been reports of challenges in designing platinum carbon (Pt/C) electrode catalysts for PEMFC. Pt/C electrode catalysts deactivate much faster on the cathode (in moisturized O 2 ) than on the anode (in H 2 ). To understand influences of moisture and oxygen on the deactivation of the Pt/C catalysts in proton-exchange-membrane fuel cells (PEMFCs), spherical-aberration-corrected environmental transmission electron microscopy (AC-ETEM) was applied with a high-speed CCD camera. Structural changes of the Pt/C electrode catalysts were dynamically recorded in moisturized nitrogen, oxygen and hydrogen. The mass spectrometry confirmed the moisture content (between 5 to 30 %) of nitrogen driving gas through a humidifier. Coalescence of platinum nanoparticles (D = 3.24 nm) was carefully evaluated in pure N 2 and moisturized N 2 atmosphere. The Pt/C showed considerable structural weakness in a moisturized N2 atmosphere. Comparable results obtained by AC-ETEM in different gas atmospheres also suggested ways to improve the oxygen reduction reaction (ORR). In this paper, the deactivation process due to moisture (hydroxylation) of carbon supports is discussed using for comparison the movement of platinum nanoparticles measured in moisturized nitrogen and pure nitrogen atmospheres

  1. Amperometric titration of thorium and some lanthanoids in acetic-acid medium using two indicator electrodes

    International Nuclear Information System (INIS)

    Khadeev, V.A.; Gevorgyan, A.M.; Talipov, Sh.T.; Kostylev, V.S.

    1979-01-01

    The votammetric behaviour of nitriletrimethylphosphonic acid (NTMP) in the medium of anhydrous acetic acid with different backgrounds in the anode region of polarization of a platinum microdisk electrode, is studied. The optimal conditions are found for the amperometric titration with two indicator electrodes of thorium and same lanthanides by a NTMP solution in anhydrous acetic medium. The influence of foreign anions and cations on the results of titration by the NTPM solution in anhydrous acetic acid is studied. The selectivity of titration in anhydrous medium is higher than in aqueous

  2. Carbon coated stainless steel as counter electrode for dye sensitized solar cells

    Science.gov (United States)

    Prakash, Shejale Kiran; Sharma, Rakesh K.; Roy, Mahesh S.; Kumar, Mahesh

    2014-10-01

    A new type of counter electrode for dye sensitized solar cells has been fabricated using a stainless steel sheet as substrate and graphite, graphene and multiwall carbon nanotubes as the catalytic material which applied by screen printing technique. The sheet resistances of the substrates and there influence on the dye sensitized solar cells has been studied. The fabricated counter electrodes i.e. SS-graphite, SS-graphene SS-MWCNT and SS-platinum were tested for their photovoltaic response in the form of dye sensitized solar cells.

  3. Comparison of platinum/MWCNTs Nanocatalysts Synthesis Processes for Proton Exchange Membrane Fuel Cells

    Science.gov (United States)

    Liu, Xuan

    Due to the growing concerns on the depletion of petroleum based energy resources and climate change; fuel cell technologies have received much attention in recent years. Proton exchange membrane fuel cell (PEMFCs) features high energy conversion efficiency and nearly zero greenhouse gas emissions, because of its combination of the hydrogen oxidation reaction (HOR) at anode side and oxygen reduction reaction (ORR) at cathode side. Synthesis of Pt nanoparticles supported on multi walled carbon nanotubes (MWCNTs) possess a highly durable electrochemical surface area (ESA) and show good power output on proton exchange membrane (PEM) fuel cell performance. Platinum on multi-walled carbon nanotubes (MWCNTs) support were synthesized by two different processes to transfer PtCl62- from aqueous to organic phase. While the first method of Pt/MWCNTs synthesis involved dodecane thiol (DDT) and octadecane thiol (ODT) as anchoring agent, the second method used ammonium lauryl sulfate (ALS) as the dispersion/anchoring agent. The particle size and distribution of platinum were examined by high-resolution transmission electron microscope (HRTEM). The TEM images showed homogenous distribution and uniform particle size of platinum deposited on the surface of MWCNTs. The single cell fuel cell performance of the Pt/MWCNTs synthesized thiols and ALS based electrode containing 0.2 (anode) and 0.4 mg (cathode) Pt.cm-2 were evaluated using Nafion-212 electrolyte with H2 and O2 gases at 80 °C and ambient pressure. The catalyst synthesis with ALS is relatively simple compared to that with thiols and also showed higher performance (power density reaches about 1070 mW.cm -2). The Electrodes with Pt/MWCNTs nanocatalysts synthesized using ALS were characterized by cyclic voltammetry (CV) for durability evaluation using humidified H2 and N2 gases at room temperature (21 °C) along with commercial Pt/C for comparison. The ESA measured by cyclic voltammetry between 0.15 and 1.2 V showed significant

  4. Thiosemicarbazone complexes of the platinum metals. A story of ...

    Indian Academy of Sciences (India)

    Unknown

    Thiosemicarbazone complexes; platinum metals; variable coordination; ... carbonylic carbon via one or two intervening atoms, D,N,S tricoordination usually takes .... modelling studies show that in this coordination mode, the phenyl ring of the.

  5. Synthesis of platinum nanowheels using a bicellar template.

    Science.gov (United States)

    Song, Yujiang; Dorin, Rachel M; Garcia, Robert M; Jiang, Ying-Bing; Wang, Haorong; Li, Peng; Qiu, Yan; van Swol, Frank; Miller, James E; Shelnutt, John A

    2008-09-24

    Disk-like surfactant bicelles provide a unique meso-structured reaction environment for templating the wet-chemical reduction of platinum(II) salt by ascorbic acid to produce platinum nanowheels. The Pt wheels are 496 +/-55 nm in diameter and possess thickened centers and radial dendritic nanosheets (about 2-nm in thickness) culminating in flared dendritic rims. The structural features of the platinum wheels arise from confined growth of platinum within the bilayer that is also limited at edges of the bicelles. The size of CTAB/FC7 bicelles is observed to evolve with the addition of Pt(II) complex and ascorbic acid. Synthetic control is demonstrated by varying the reaction parameters including metal salt concentration, temperature, and total surfactant concentration. This study opens up opportunities for the use of other inhomogeneous soft templates for synthesizing metals, metal alloys, and possibly semiconductors with complex nanostructures.

  6. Wireless gas sensing in South African underground platinum mines

    CSIR Research Space (South Africa)

    Abu-Mahfouz, Adnan M

    2014-04-01

    Full Text Available Approximately 70% of South African mines are classified as fiery, where methane gas potentially could cause explosions. The number of flammable gas reports and accidents are increasing steadily for both gold and platinum mines. However...

  7. Nanoparticulate platinum films on gold using dendrimer-based wet ...

    Indian Academy of Sciences (India)

    Central Electrochemical Research Institute, Karaikudi 630 006, India. E-mail: ... deposition methods for applications involving thin films, e.g., catalysis. Deposition of platinum .... The spectrum recorded at 0.3 V shows a mixed control behaviour ...

  8. Joint U. S. --U. S. S. R. test of U. S. MHD electrode systems in U. S. S. R. U-02 MHD facility (phase I). Final report

    Energy Technology Data Exchange (ETDEWEB)

    Hosler, W R [ed.

    1976-01-01

    The first (Phase I) joint U.S.-U.S.S.R. test of U.S. electrode materials was carried out in Moscow between September 25 and October 8, 1975 in the Soviet U-02 MHD facility. The test procedure followed closely a predetermined work plan designed to test five different zirconia based materials and the cathode and anode electrode wall modules under MHD operating conditions. The materials which were selected were 88Zr0/sub 2/-12Y/sub 2/0/sub 3/, 82Zr0/sub 2/-18Ce02, 50Zr0/sub 2/-50Ce0/sub 2/, 25Zr0/sub 2/-75Ce0/sub 2/ and 20Zr0/sub 2/-78Ce0/sub 2/-2Ta/sub 2/0/sub 5/. The electrode modules were constructed by Westinghouse Research and Development Laboratory. Each of the five electrode materials had four different current densities established between the anode and cathode during the experiment which lasted a total of 127 hours. There were four main phases in the test schedule: (1) start-up of the channel over a specific heating period. No seed (K/sub 2/C0/sub 3/) introduction - 18 hours. (2) Electrical tests at operating temperature to investigate electro-physical characteristics of the channel and electrodes - 6 hours. (3) Operating life test - 94 hours. (4) Shut-down of the channel over a specific cool down period - 9 hours. All except six electrode pairs performed satisfactorily during the entire test. These were the pairs which were designated to carry maximum or near maximum current density. Five pairs failed early in the life test and the sixth pair failed in the last several hours. Failure was not due to the electrode materials, however, but due to lead-out melting caused by joule heating in the platinum wires. The U-02 facility is described and the operational parameters are given for each phase of the test. The electrode and insulating walls are described and the appropriate parameters that are used to predict the performance of the module are given.

  9. Electrochemical behaviour of platinum in hydrogen peroxide solution (1963); Comportement electrochimique du platine en solution d'eau oxygene (1963)

    Energy Technology Data Exchange (ETDEWEB)

    Prost, G H [Commisariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1963-06-15

    The relative stability of hydrogen peroxide in aqueous solution at 25 deg. C, allows its amperometric determination from the theory, using either its cathodic reduction or its anodic oxidation. The cathodic reduction yields a wave on a platinum electrode only when some oxygen is present in the solution. It cannot, therefore, be used for electrochemical determination. On the other hand, the anodic oxidation on platinum produces a wave which might be used. However, a passivation of platinum occurs at the same time. This passivation process is studied by means of potentio-kinetic, potentio-static, intensio-static curves and of pH measurements in the vicinity of the anode. A mechanism for passivation is presented, which takes into account the role of hydrogen peroxide as a reducing agent. This passivation rules out any analytical application of the oxidation reaction of hydrogen peroxide. (author) [French] La stabilite relative de l'eau oxygenee en solution aqueuse a 25 deg. C permet d'envisager theoriquement son dosage par amperometrie, en utilisant soit sa reduction cathodique, soit son oxydation anodique. La reduction cathodique ne donne lieu a une vague sur electrode de platine qu'en presence d'oxygene dissous. Il n'est donc pas utilisable pour un dosage. L'oxydation anodique sur platine donne une vague theoriquement utilisable mais s'accompagne d'une passivation du platine. Le processus de la passivation est etudie au moyen des courbes potentiocinetiques, potentiostatiques, intensiostatiques et par une mesure des variations de pH au voisinage de l'anode. On propose un mecanisme de passivation en tenant compte du role activant de l'eau oxygenee. Cette passivation interdit toute application analytique de la reaction d'oxydation de l'eau oxygenee. (auteur)

  10. Electrodeposition of platinum metals and alloys from chloride melts

    Directory of Open Access Journals (Sweden)

    Saltykova N.A.

    2003-01-01

    Full Text Available The structure of platinum metals and their alloys deposited by the electrolysis of chloride melts have been investigated. The cathodic deposits were both in the form of compact layers and dendrites. All the alloys of platinum metals obtained are solid solutions in the whole range of composition. Depending on the experimental conditions the layers had columnar, stratum and spiral (dissipative structures. The stratum and dissipative structures were observed in the case of alloys only.

  11. Determination of microquantities of silver in platinum by isotope dilution

    International Nuclear Information System (INIS)

    Yedinakova, V.; Sladkovska, Y.

    1980-01-01

    A method is described for determining microquantities of silver in platinum. It is based on isotope dilution by means of substoichiometric extraction of dithizonates with carbon tetrachloride. The determination of silver according to this technique is not interfered by zinc or gold in quantities exceeding the silver content by one order of magnitude nor by a great excess of platinum. In the presence of copper the addition of complexon is necessary. (author)

  12. Platinum group metal nitrides and carbides: synthesis, properties and simulation

    International Nuclear Information System (INIS)

    Ivanovskii, Alexander L

    2009-01-01

    Experimental and theoretical data on new compounds, nitrides and carbides of the platinum group 4d and 5d metals (ruthenium, rhodium, palladium, osmium, iridium, platinum), published over the past five years are summarized. The extreme mechanical properties of platinoid nitrides and carbides, i.e., their high strength and low compressibility, are noted. The prospects of further studies and the scope of application of these compounds are discussed.

  13. A comparison study of electrodes for neonate electrical impedance tomography

    International Nuclear Information System (INIS)

    Rahal, Mohamad; Demosthenous, Andreas; Khor, Joo Moy; Tizzard, Andrew; Bayford, Richard

    2009-01-01

    Electrical impedance tomography (EIT) is an imaging technique that has the potential to be used for studying neonate lung function. The properties of the electrodes are very important in multi-frequency EIT (MFEIT) systems, particularly for neonates, as the skin cannot be abraded to reduce contact impedance. In this work, the impedance of various clinical electrodes as a function of frequency is investigated to identify the optimum electrode type for this application. Six different types of self-adhesive electrodes commonly used in general and neonatal cardiology have been investigated. These electrodes are Ag/AgCl electrodes from the Ambu® Cardiology Blue sensors range (BR, NF and BRS), Kendall (KittyCat(TM) and ARBO®) and Philips 13953D electrodes. In addition, a textile electrode without gel from Textronics was tested on two subjects to allow comparison with the hydrogel-based electrodes. Two- and four-electrode measurements were made to determine the electrode-interface and tissue impedances, respectively. The measurements were made on the back of the forearm of six healthy adult volunteers without skin preparation with 2.5 cm electrode spacing. Impedance measurements were carried out using a Solartron SI 1260 impedance/gain-phase analyser with a frequency range from 10 Hz to 1 MHz. For the electrode-interface impedance, the average magnitude decreased with frequency, with an average value of 5 kΩ at 10 kHz and 337 Ω at 1 MHz; for the tissue impedance, the respective values were 987 Ω and 29 Ω. Overall, the Ambu BRS, Kendall ARBO® and Textronics textile electrodes gave the lowest electrode contact impedance at 1 MHz. Based on the results of the two-electrode measurements, simple RC models for the Ambu BRS and Kendall-ARBO and Textronics textile electrodes have been derived for MFEIT applications

  14. Uncharged positive electrode composition

    Science.gov (United States)

    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.

  15. A freeze-dried graphene counter electrode enhances the performance of dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Hung, Kai-Hsiang; Wang, Hong-Wen, E-mail: hongwen@cycu.edu.tw

    2014-01-01

    A flexible graphene/polyimide (PI) counter electrode without a fluorine-doped tin oxide (FTO) layer has been fabricated for dye-sensitized solar cell (DSSCs) applications. The flexible counter electrode consists of polyimide double-sided tape as a substrate beneath a graphene film acting as the conductive and catalytic layer. Chemically reduced graphene oxide (rGO) on the PI electrode (rGO-PI) shows comparable catalytic activity to that of the reference sputtered platinum/FTO counter electrodes (Sputter-Pt/FTO). A DSSC with a freeze-dried rGO-PI (FD-rGO-PI) counter electrode shows an overall conversion efficiency (η) of 5.45%, while that of the conventional Sputter-Pt/FTO electrode is 5.52%. The DSSC with a thermally dried rGO-PI (Gel-rGO-PI) counter electrode (not freeze-dried) exhibits a smooth morphology and much poorer performance (η = 1.61%). Field emission scanning electron microscopy, electrochemical impedance spectroscopy, and cyclic voltammetry measurements demonstrate that the FD-rGO-PI electrode possesses a porous structure, numerous edges, minimum charge-transfer resistance and a higher electrocatalytic activity toward the I{sub 3}{sup −}/I{sup −} redox couple than that of the Gel-rGO-PI electrode. The high electrocatalytic activity, facile preparation procedure, absence of FTO, and material flexibility render the FD-rGO-PI electrode an ideal alternative to conventional DSSC counter electrodes. - Highlights: • Highly rough and conductive graphene-based counter electrode is synthesized. • The characteristics of graphene surface by freeze drying are different. • The graphene counter electrode exhibits comparable performance to that of sputtered Pt one.

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

    International Nuclear Information System (INIS)

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

    2012-01-01

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

  17. Electro catalyst of platinum prepared by CVD for the oxygen reduction reaction

    International Nuclear Information System (INIS)

    Garcia C, M.A.; Fernandez V, S.M.; Vargas G, J.R.

    2004-01-01

    In this work it is reported the preparation and characterization of platinum films obtained by the technique of chemical vapor deposition at low pressure, better well-known as LPCVD for their initials in English (Low Pressure Chemical Vapor Deposition). The technique has several industrial applications and in this work it is explored their possible use to prepare applicable electrocatalysts in fuel cells. The films were characterized by XRD, SEM, EDS and they were proven for to determine their acting in the Oxygen reduction reaction (Orr) in sulfuric acid 0.5 M, the results show that the material presents good activity for the reaction in study. (Author)

  18. Piercing by composite electrode tool

    International Nuclear Information System (INIS)

    Abdukarimov, Eh.T.; Krakov, B.G.; Saidinov, S.Ya.

    1990-01-01

    The construction of the electrode consisting of a dielectric shell, where a working liquid enters, and a metal rod is designed for precision super-deep piercing by the electroerosion treatment method. Technological parameters of piercing with small diameter (0.5-1.9 mm) for 12Kh18N10T steel, copper and tungsten are presented. A possibility to use a new tool for treating components of any form and sizes is marked

  19. Potentiometric titration with polarized electrodes

    International Nuclear Information System (INIS)

    Chikryzova, E.G.

    1977-01-01

    Based on the analysis of the works carried out during 1911-75 consideration is given to the present state of the method of potentiometric titration with polarized electrodes. The material is generalized in the tabular form indicating the elments of interest, titration conditions and the objects to be analyzed. The list and classification of the potentiometric titration methods intended for determining organic and inorganic substances are presented

  20. Platinum stable isotopes in ferromanganese crust and nodules

    Science.gov (United States)

    Corcoran, Loretta; Seward, Terry; Handler, Monica R.

    2015-04-01

    Hydrogenetic ferromanganese (Fe-Mn) crust and nodules are slow-growing chemical sediments that form by direct precipitation from seawater, resulting in a record of changing seawater chemistry. These sediments are the primary sink for platinum in the modern oxic marine environment, hosting well-documented enrichments over other platinum-group elements (PGEs): the Pt anomaly [1]. Platinum is a non-bio-essential, highly siderophile, transition metal with six stable isotopes (190Pt, 192Pt, 194Pt, 195Pt, 196Pt, and 198Pt) with several oxidation states (Pt0, Pt2+ and Pt4+). Platinum is generally considered to exist in the hydrosphere as Pt2+ although its behaviour in the marine environment is poorly constrained, and Pt4+may also be present. Variations in ocean redox state, together with changes in source fluxes to the oceans, may therefore lead to small variations (Leaching experiments conducted on platinum rich terrestrial materials underwent platinum stable isotopic measurement as an analogue for the Pt isotopic fractionation associated with continental weathering. [1] Hodge, V.F. et al. (1985) Earth and Planetary Science Letters, 72, 158-162. [2] Creech, J. et al. (2013) Journal of Analytical Atomic Spectrometry, 28. 853-865.

  1. Exosomes as mediators of platinum resistance in ovarian cancer.

    Science.gov (United States)

    Crow, Jennifer; Atay, Safinur; Banskota, Samagya; Artale, Brittany; Schmitt, Sarah; Godwin, Andrew K

    2017-02-14

    Exosomes have been implicated in the cell-cell transfer of oncogenic proteins and genetic material. We speculated this may be one mechanism by which an intrinsically platinum-resistant population of epithelial ovarian cancer (EOC) cells imparts its influence on surrounding tumor cells. To explore this possibility we utilized a platinum-sensitive cell line, A2780 and exosomes derived from its resistant subclones, and an unselected, platinum-resistant EOC line, OVCAR10. A2780 cells demonstrate a ~2-fold increase in viability upon treatment with carboplatin when pre-exposed to exosomes from platinum-resistant cells as compared to controls. This coincided with increased epithelial to mesenchymal transition (EMT). DNA sequencing of EOC cell lines revealed previously unreported somatic mutations in the Mothers Against Decapentaplegic Homolog 4 (SMAD4) within platinum-resistant cells. A2780 cells engineered to exogenously express these SMAD4 mutations demonstrate up-regulation of EMT markers following carboplatin treatment, are more resistant to carboplatin, and release exosomes which impart a ~1.7-fold increase in resistance in naive A2780 recipient cells as compared to controls. These studies provide the first evidence that acquired SMAD4 mutations enhance the chemo-resistance profile of EOC and present a novel mechanism in which exchange of tumor-derived exosomes perpetuates an EMT phenotype, leading to the development of subpopulations of platinum-refractory cells.

  2. High performance platinum single atom electrocatalyst for oxygen reduction reaction

    Science.gov (United States)

    Liu, Jing; Jiao, Menggai; Lu, Lanlu; Barkholtz, Heather M.; Li, Yuping; Wang, Ying; Jiang, Luhua; Wu, Zhijian; Liu, Di-Jia; Zhuang, Lin; Ma, Chao; Zeng, Jie; Zhang, Bingsen; Su, Dangsheng; Song, Ping; Xing, Wei; Xu, Weilin; Wang, Ying; Jiang, Zheng; Sun, Gongquan

    2017-07-01

    For the large-scale sustainable implementation of polymer electrolyte membrane fuel cells in vehicles, high-performance electrocatalysts with low platinum consumption are desirable for use as cathode material during the oxygen reduction reaction in fuel cells. Here we report a carbon black-supported cost-effective, efficient and durable platinum single-atom electrocatalyst with carbon monoxide/methanol tolerance for the cathodic oxygen reduction reaction. The acidic single-cell with such a catalyst as cathode delivers high performance, with power density up to 680 mW cm-2 at 80 °C with a low platinum loading of 0.09 mgPt cm-2, corresponding to a platinum utilization of 0.13 gPt kW-1 in the fuel cell. Good fuel cell durability is also observed. Theoretical calculations reveal that the main effective sites on such platinum single-atom electrocatalysts are single-pyridinic-nitrogen-atom-anchored single-platinum-atom centres, which are tolerant to carbon monoxide/methanol, but highly active for the oxygen reduction reaction.

  3. In vitro permeation of platinum and rhodium through Caucasian skin.

    Science.gov (United States)

    Franken, A; Eloff, F C; Du Plessis, J; Badenhorst, C J; Jordaan, A; Du Plessis, J L

    2014-12-01

    During platinum group metals (PGMs) refining the possibility exists for dermal exposure to PGM salts. The dermal route has been questioned as an alternative route of exposure that could contribute to employee sensitisation, even though literature has been focused on respiratory exposure. This study aimed to investigate the in vitro permeation of platinum and rhodium through intact Caucasian skin. A donor solution of 0.3mg/ml of metal, K2PtCl4 and RhCl3 respectively, was applied to the vertical Franz diffusion cells with full thickness abdominal skin. The receptor solution was removed at various intervals during the 24h experiment, and analysed with high resolution ICP-MS. Skin was digested and analysed by ICP-OES. Results indicated cumulative permeation with prolonged exposure, with a significantly higher mass of platinum permeating after 24h when compared to rhodium. The mass of platinum retained inside the skin and the flux of platinum across the skin was significantly higher than that of rhodium. Permeated and skin retained platinum and rhodium may therefore contribute to sensitisation and indicates a health risk associated with dermal exposure in the workplace. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Structure-activity relationships of carbon-supported platinum-bismuth and platinum-antimony oxidation catalysts

    CSIR Research Space (South Africa)

    Maphoru, MV

    2017-04-01

    Full Text Available Compositional and morphological studies on supported platinum are important for the improvement and expanded use of catalysts for oxidative coupling reactions. Nanocomposites consisting of 5% Pt supported on activated carbon and promoted with 5% Bi...

  5. Handbook of reference electrodes

    CERN Document Server

    Inzelt, György; Scholz, Fritz

    2013-01-01

    Reference Electrodes are a crucial part of any electrochemical system, yet an up-to-date and comprehensive handbook is long overdue. Here, an experienced team of electrochemists provides an in-depth source of information and data for the proper choice and construction of reference electrodes. This includes all kinds of applications such as aqueous and non-aqueous solutions, ionic liquids, glass melts, solid electrolyte systems, and membrane electrodes. Advanced technologies such as miniaturized, conducting-polymer-based, screen-printed or disposable reference electrodes are also covered. Essen

  6. Electrochemical behavior of LiCoO2 as aqueous lithium-ion battery electrodes

    KAUST Repository

    Ruffo, Riccardo; Wessells, Colin; Huggins, Robert A.; Cui, Yi

    2009-01-01

    .e., as the counter electrode. A commercial reference electrode is also present. Both the working and the counter electrodes have been prepared as thin layers on a metallic substrate using the procedures typical for the study of electrodes for lithium-ion batteries

  7. Iodide selective membrane electrodes based on a Molybdenum-Salen as a neutral carrier

    Energy Technology Data Exchange (ETDEWEB)

    Ghanei-Motlagh, Masoud [Department of Chemistry, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Taher, Mohammad Ali, E-mail: ma_taher@yahoo.com [Department of Chemistry, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of); Ahmadi, Kyoumars [AJA University of Medical Sciences, Tehran (Iran, Islamic Republic of); Sheikhshoaie, Iran [Department of Chemistry, Shahid Bahonar University of Kerman, Kerman (Iran, Islamic Republic of)

    2011-12-01

    A new polymeric membrane electrode (PME) and a coated platinum disk electrode (CPtE) based on Schiff base complex of Mo(VI) as a suitable carrier for I{sup -} ion were described. The influence of membrane composition, pH and possible interfering anions were investigated on the response properties of the electrodes. The electrodes exhibited a Nernstian slope of 63.0 {+-} 0.5 (CPtE) and 60.3 {+-} 0.4 (PME) mV decade{sup -1} in I{sup -} ion over a wide concentration range from 7.9 x 10{sup -7} to 1.0 x 10{sup -1} M for CPtE and 9.1 x 10{sup -6} to 1.0 x 10{sup -1} M I{sup -} for PME. The potentiometric response of the electrodes was independent of the pH of the test solution in the pH range 2.0-8.5 with a fast response time (< 10 s). The process of transfer of iodide across the membrane interface was investigated by use of the AC impedance technique. The proposed sensors were successfully applied to direct determination of iodide in samples containing interfering anions, waste water and as indicator electrodes in precipitation titrations. Highlights: {yields} We study new selective membrane electrodes for iodide ions. {yields} To the best of our knowledge this is the first coated platinum disk electrode of I{sup -}. {yields} The sensors have a wide concentration range with a fast response time. {yields} Efforts have been made to improve the selectivity with the use of CPtE.

  8. Influence of electroformation regime on the specific properties of cobalt oxide‒platinum composite films deposited on conductive diamond

    Energy Technology Data Exchange (ETDEWEB)

    Spătaru, Tanţa; Osiceanu, Petre; Preda, Loredana; Munteanu, Cornel [Institute of Physical Chemistry “Ilie Murgulescu”, 202 Spl. Independenţei 060021, Bucharest (Romania); Spătaru, Nicolae, E-mail: nspataru@icf.ro [Institute of Physical Chemistry “Ilie Murgulescu”, 202 Spl. Independenţei 060021, Bucharest (Romania); Fujishima, Akira [Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku Tokyo 162-8601 (Japan)

    2014-04-01

    Two straightforward electrochemical methods were used in the present work for depositing cobalt oxide-platinum composite films on boron-doped diamond substrates in order to put into evidence the effect of the electroformation regime on the morphological and electrochemical features of these hybrid systems. The shift from potentiostatic to potentiodynamic deposition enabled not only a significant improvement of the Pt particles dispersion but also a much higher surface concentration of oxygenated species of platinum. For similar Co{sub 3}O{sub 4} and Pt loadings, the specific capacitance of the composite films deposited by cyclic voltammetry was with ca. 8% higher than that of the potentiostatically obtained ones. Additional advantage of potentiodynamic deposition is the improved resistance to fouling during methanol anodic oxidation of Pt particles, tentatively ascribed to the higher surface concentration of oxygenated species of platinum. - Highlights: • Cobalt oxide-platinum composite films were electrodeposited on conductive diamond. • Composite films formed by cyclic voltammetry exhibit enhanced specific capacitance. • Potentiodynamic deposition enables higher concentration of oxygenated Pt species. • Co{sub 3}O{sub 4}–Pt films prepared by cyclic voltammetry are less susceptible to CO poisoning.

  9. Electrodeposition of a Pt-PrO{sub 2-x} electrocatalyst on diamond electrodes for the oxidation of methanol

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Liang; Hu, Jingping; Foord, John S. [Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford OX1 3TA (United Kingdom)

    2012-09-15

    The electrodeposition of Pt-PrO{sub 2-x} nanostructures on boron-doped diamond electrodes was explored by decorating platinum nanoparticles with praseodymium oxide, for application as an electrocatalyst in the electrooxidation of methanol in direct methanol fuel cells. A high loading of platinum with good stability was deposited by adopting a two-stage protocol, which involved a stepped potential route and a chronoamperometric approach. Praseodymium oxide was then coated on the platinum particles from solutions containing praseodymium nitrate and hydrogen peroxide. The porous microstructure of the resulting catalyst was characterized by X-ray photoelectron spectroscopy and scanning electron microscope, along with electrochemical measurement. The addition of praseodymium oxide to the Pt resulted in a higher catalytic activity profile for methanol oxidation along with an improved resistance to poisoning effects caused by incompletely oxidized carbonaceous species. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Nuclear analytical methods for platinum group elements

    International Nuclear Information System (INIS)

    2005-04-01

    Platinum group elements (PGE) are of special interest for analytical research due to their economic importance like chemical peculiarities as catalysts, medical applications as anticancer drugs, and possible environmental detrimental impact as exhaust from automobile catalyzers. Natural levels of PGE are so low in concentration that most of the current analytical techniques approach their limit of detection capacity. In addition, Ru, Rh, Pd, Re, Os, Ir, and Pt analyses still constitute a challenge in accuracy and precision of quantification in natural matrices. Nuclear analytical techniques, such as neutron activation analysis, X ray fluorescence, or proton-induced X ray emission (PIXE), which are generally considered as reference methods for many analytical problems, are useful as well. However, due to methodological restrictions, they can, in most cases, only be applied after pre-concentration and under special irradiation conditions. This report was prepared following a coordinated research project and a consultants meeting addressing the subject from different viewpoints. The experts involved suggested to discuss the issue according to the (1) application, hence, the concentration levels encountered, and (2) method applied for analysis. Each of the different fields of application needs special consideration for sample preparation, PGE pre-concentration, and determination. Additionally, each analytical method requires special attention regarding the sensitivity and sample type. Quality assurance/quality control aspects are considered towards the end of the report. It is intended to provide the reader of this publication with state-of-the-art information on the various aspects of PGE analysis and to advise which technique might be most suitable for a particular analytical problem related to platinum group elements. In particular, many case studies described in detail from the authors' laboratory experience might help to decide which way to go. As in many cases

  11. Electrochemical characterization of platinum nanoparticles stabilized by amines

    International Nuclear Information System (INIS)

    Ramirez-Meneses, E.; Dominguez-Crespo, M.A.; Montiel-Palma, V.; Chavez-Herrera, V.H.; Gomez, E.; Hernandez-Tapia, G.

    2009-01-01

    In this work we present the synthesis by Chaudret approach of Pt nanoparticles stabilized by primary amine (-NH 2 ) compounds. Their electrochemical performance as cathodes in low temperature polymer electrolite fuel cells on the oxygen reduction reaction (ORR) is also presented. Transmission electron microscopy (TEM) images of the samples show Pt nanostructures with particle size varying from 10 to 100 nm depending on the kind of the stabilizer used during the catalyst preparation. In some cases well-dispersed isolated platinum nanoparticles were observed. The activity of the dispersed catalysts (Pt/C) with respect to the ORR was investigated using steady state polarization measurements. The kinetic parameters showed that although no significant differences between the Tafel slopes of the Pt catalysts exist, transfer coefficients and exchange current densities show higher activities when the Pt nanoparticles were stabilized by tert-butylamine (TBA). The performance with respect to the ORR of the Pt/C catalyst on vulcan carbon substrate is active and comparable to that reported in the literature for state-of-art electrocatalysts.

  12. Band structure in Platinum nuclei (A ∼ 182)

    International Nuclear Information System (INIS)

    Popescu, D.G.

    1991-01-01

    In this thesis, the author studies the band structure in Platinum nuclei and has divided his work in 5 parts: in the first, the author makes a general presentation of nucleus physics with a high angular momentum and introduces to the deformed nucleus notion -axial, triaxial or mixing of different deformations. The notion of form co-existence will be used to interpret the experimental results. In the second part, the author describes the detection means which have been used to make measurements. An abstract of theoretical notions, usefull for the understanding of fusion-evaporation reaction is presented. The author explains the details, performances and different modes of using of 'Chateau de cristal' and others used spectrometers. In the third part, the author presents all experimental data. He has effected γ coincidence measurements for Pt, Au and Ir nuclei. In the fourth part, for a classical analysis or an interpretation in the frame of cranking model the author presents theoretical models which are adapted at the study of high spin states and band structures

  13. Modelling and sensitivity analysis of urinary platinum excretion in anticancer chemotherapy for the recovery of platinum

    DEFF Research Database (Denmark)

    Folens, Karel; Mortier, Séverine Thérèse F C; Baeten, Janis

    2016-01-01

    Platinum (Pt) based antineoplastics are important in cancer therapy. To date the Pt which is urinary excreted by the patients ends up in wastewater. This is disadvantageous from both an economic as from an ecological point of view because Pt is a valuable material and the excretion products...... are toxic for aquatic organisms. Therefore, efforts should be made to recover the Pt. The urinary excretion of Pt from two antineoplastics are taken under consideration, i.e. cisplatin and carboplatin. Using these reference compounds, a scenario analysis based on administration statistics from Ghent...

  14. An impending platinum crisis and its implications for the future of the automobile

    International Nuclear Information System (INIS)

    Yang, C.-J.

    2009-01-01

    The global demand for platinum has consistently outgrown supply in the past decade. This trend likely will continue and the imbalance may possibly escalate into a crisis. Platinum plays pivotal roles in both conventional automobile emissions control and the envisioned hydrogen economy. A platinum crisis would have profound implications on energy and environment. On the one hand, inadequate platinum supply will prevent widespread commercialization of hydrogen fuel-cell vehicles. On the other hand, expensive platinum may enhance the competitiveness of hybrid, plug-in hybrid, and battery-powered electric cars. Policymakers should weigh the potential impacts of a platinum crisis in energy policy.

  15. Platinum-group elements and gold in base metal sulfides, platinum-group minerals, and Re-Os isotope compositions of the Uitkomst complex, South Africa

    Czech Academy of Sciences Publication Activity Database

    Trubač, Jakub; Ackerman, Lukáš; Gauert, Ch.; Ďurišová, Jana; Hrstka, Tomáš

    2018-01-01

    Roč. 113, č. 2 (2018), s. 439-461 ISSN 0361-0128 R&D Projects: GA ČR GA13-15390S Institutional support: RVO:67985831 Keywords : binary alloys * copper compounds * economic geology * gold * iridium * isotopes * ore deposits * osmium * palladium * platinum * platinum metals * pyrites * Rhenium * rhenium alloys * ruthenium * solid solutions * sulfur compounds * crustal materials * mass-balance calculations * massive sulfides * mineralized zone * monosulfide solid solutions * platinum group elements * platinum group elements (PGEs) * platinum group minerals Subject RIV: DB - Geology ; Mineralogy; AC - Archeology, Anthropology, Ethnology (ARUB-Q) OBOR OECD: Geology; Archaeology (ARUB-Q) Impact factor: 2.519, year: 2016

  16. Evaluation of the electrode performance for PAFC by using acid absorption, acceleration and ac-impedance measurement

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chang-Soo; Song, Rak-Hyun; Choi, Byung-Woo [Korea Institute of Energy Research, Taejon (Korea, Republic of)] [and others

    1996-12-31

    In PAFC, the degradation on cathode electrode caused by carbon corrosion, platinum dissolution and growth is especially severe. An acceleration test is a good technique for evaluating the degradation of electrode performance, because it does not need long time. Coleman et al used thermal cycling and on-off cycling as an acceleration test. Song et al showed that hydrogen shortage decreased the electrode performance more rapidly than that of air shortage in gas shortage test. Honji et al reported that the rate of coarsening of Pt particle is rapid in open circuit potential and this is one of major causes on the performance degradation of electrode. The cathode performance has been studied by using acid absorption, acceleration and ac-impedance measurements as functions of the polytetrafluoroethylene (PTFE) contents and sintering temperatures of the electrode.

  17. Palladium-Based Catalysts as Electrodes for Direct Methanol Fuel Cells: A Last Ten Years Review

    Directory of Open Access Journals (Sweden)

    Juan Carlos Calderón Gómez

    2016-08-01

    Full Text Available Platinum-based materials are accepted as the suitable electrocatalysts for anodes and cathodes in direct methanol fuel cells (DMFCs. Nonetheless, the increased demand and scarce world reserves of Pt, as well as some technical problems associated with its use, have motivated a wide research focused to design Pd-based catalysts, considering the similar properties between this metal and Pt. In this review, we present the most recent advancements about Pd-based catalysts, considering Pd, Pd alloys with different transition metals and non-carbon supported nanoparticles, as possible electrodes in DMFCs. In the case of the anode, different reported works have highlighted the capacity of these new materials for overcoming the CO poisoning and promote the oxidation of other intermediates generated during the methanol oxidation. Regarding the cathode, the studies have showed more positive onset potentials, as fundamental parameter for determining the mechanism of the oxygen reduction reaction (ORR and thus, making them able for achieving high efficiencies, with less production of hydrogen peroxide as collateral product. This revision suggests that it is possible to replace the conventional Pt catalysts by Pd-based materials, although several efforts must be made in order to improve their performance in DMFCs.

  18. Phytochelatin Modified Electrode Surface as a Sensitive Heavy- Metal Ion Biosensor

    Directory of Open Access Journals (Sweden)

    Rene Kizek

    2005-02-01

    Full Text Available Electrochemical biosensors have superior properties over other existingmeasurement systems because they can provide rapid, simple and low-cost on-fielddetermination of many biological active species and a number of dangerous pollutants. Inour work, we suggested a new heavy metal biosensor based on interaction of heavy metalions (Cd2+ and Zn2+ with phytochelatin, which was adsorbed on the surface of the hangingmercury drop electrode, using adsorptive transfer stripping differential pulse voltammetry.In addition, we applied the suggested technique for the determination of heavy metals in abiological sample – human urine and platinum in a pharmaceutical drug. The detectionlimits (3 S/N of Cd(II, Zn(II and cis-platin were about 1.0, 13.3 and 1.9 pmole in 5 μl,respectively. On the basis of the obtained results, we propose that the suggested techniqueoffers simple, rapid, and low-cost detection of heavy metals in environmental, biologicaland medical samples.

  19. Development of a membrane electrode assembly production process for proton exchange membrane fuel cell (PEMFC) by sieve printing

    International Nuclear Information System (INIS)

    Bonifacio, Rafael Nogueira

    2010-01-01

    Energy is a resource that presents historical trend of growth in demand. Projections indicate that future energy needs will require a massive use of hydrogen as fuel. The use of systems based on the use of proton exchange membrane fuel cell (PEMFC) has features that allow its application for stationary applications, automotive and portable power generation. The use of hydrogen as fuel for PEMFC has the advantage low pollutants' emission, when compared to fossil fuels. For the reactions in a PEMFC is necessary to build membrane electrode assembly (MEA). And the production of MEAs and its materials are relevant to the final cost of kW of power generated by systems of fuel cell. This represent currently a technological and financial barriers to large-scale application of this technology. In this work a process of MEAs fabrication were developed that showed high reproducibility, rapidity and low cost by sieve printing. The process of sieve printing and the ink composition as a precursor to the catalyst layer were developed, which allow the preparation of electrodes for MEAs fabrication with the implementation of the exact catalyst loading, 0.6 milligrams of platinum per square centimeters (mgPt.cm -2 ) suitable for cathodes and 0.4 mgPt.cm -2 for anode in only one application step per electrode. The ink was developed, produced, characterized and used with similar characteristics to ink of sieve printing build for other applications. The MEAs produced had a performance of up to 712 mA.cm -2 by 600 mV to 25 cm 2 MEA area. The MEA cost production for MEAs of 247.86 cm 2 , that can generate 1 kilowatt of energy was estimated to US$ 7,744.14 including cost of equipment, materials and labor. (author)

  20. Electrode stabilizing materials

    Science.gov (United States)

    Amine, Khalil; Abouimrane, Ali; Moore, Jeffrey S.; Odom, Susan A.

    2015-11-03

    An electrolyte includes a polar aprotic solvent; an alkali metal salt; and an electrode stabilizing compound that is a monomer, which when polymerized forms an electrically conductive polymer. The electrode stabilizing compound is a thiophene, a imidazole, a anilines, a benzene, a azulene, a carbazole, or a thiol. Electrochemical devices may incorporate such electrolytes.

  1. Durable fuel electrode

    DEFF Research Database (Denmark)

    2017-01-01

    the composite. The invention also relates to the use of the composite as a fuel electrode, solid oxide fuel cell, and/or solid oxide electrolyser. The invention discloses a composite for an electrode, comprising a three-dimensional network of dispersed metal particles, stabilised zirconia particles and pores...

  2. Electrodeposition of flower-like platinum on electrophoretically grown nitrogen-doped graphene as a highly sensitive electrochemical non-enzymatic biosensor for hydrogen peroxide detection

    Energy Technology Data Exchange (ETDEWEB)

    Tajabadi, M.T. [University Malaya Centre for Ionic Liquids, Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603 (Malaysia); Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603 (Malaysia); Sookhakian, M., E-mail: m.sokhakian@gmail.com [University Malaya Centre for Ionic Liquids, Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603 (Malaysia); Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603 (Malaysia); Department of Mechanical Convergence Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 133-791, Korea (Korea, Republic of); Zalnezhad, E., E-mail: erfan@hanyang.ac.kr [Department of Mechanical Convergence Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 133-791, Korea (Korea, Republic of); Yoon, G.H. [Department of Mechanical Convergence Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul, 133-791, Korea (Korea, Republic of); Hamouda, A.M.S. [Mechanical and Industrial Engineering Department, College of Engineering, Qatar University, 2713, Doha (Qatar); Azarang, Majid [Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603 (Malaysia); Basirun, W.J. [Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603 (Malaysia); Institute of Nanotechnology & Catalysis Research, Institute of Postgraduate Studies, University Malaya, 50603 Kuala Lumpur (Malaysia); Alias, Y., E-mail: yatimah70@um.edu.my [University Malaya Centre for Ionic Liquids, Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603 (Malaysia); Department of Chemistry, Faculty of Science, University of Malaya, Kuala Lumpur 50603 (Malaysia)

    2016-11-15

    Highlights: • Nitrogen doped graphene with different thickness by electrophoretic deposition. • The conductivity of N-graphene layer depends on the tickness. • Support of platinum shows efficient electrocatalytic performance for biosensor. • CV curves and amperometric responses improved and optimized in the presence of N-graphene. - Abstract: An efficient non-enzymatic biosensor electrode consisting of nitrogen-doped graphene (N-graphene) and platinum nanoflower (Pt NF) with different N-graphene loadings were fabricated on indium tin oxide (ITO) glass using a simple layer-by-layer electrophoretic and electrochemical sequential deposition approach. N-graphene was synthesized by annealing graphene oxide with urea at 900 °C. The structure and morphology of the as-fabricated non-enzymatic biosensor electrodes were determined using X-ray diffraction, field emission electron microscopy, transmission electron microscopy, Raman and X-ray photoelectron spectra. The as-fabricated Pt NF-N-graphene-modified ITO electrodes with different N-graphene loadings were utilized as a non-enzymatic biosensor electrode for the detection of hydrogen peroxide (H{sub 2}O{sub 2}). The behaviors of the hybrid electrodes towards H{sub 2}O{sub 2} reduction were assessed using chronoamperometry, cyclic voltammetry and electrochemical impedance spectroscopy analysis. The Pt NF-N-graphene-modified ITO electrode with a 0.05 mg ml{sup −1} N-graphene loading exhibited the lowest detection limit, fastest amperometric sensing, a wide linear response range, excellent stability and reproducibility for the non-enzymatic H{sub 2}O{sub 2} detection, due to the synergistic effect between the electrocatalytic activity of the Pt NF and the high conductivity and large surface area of N-graphene.

  3. Electrodeposition of flower-like platinum on electrophoretically grown nitrogen-doped graphene as a highly sensitive electrochemical non-enzymatic biosensor for hydrogen peroxide detection

    International Nuclear Information System (INIS)

    Tajabadi, M.T.; Sookhakian, M.; Zalnezhad, E.; Yoon, G.H.; Hamouda, A.M.S.; Azarang, Majid; Basirun, W.J.; Alias, Y.

    2016-01-01

    Highlights: • Nitrogen doped graphene with different thickness by electrophoretic deposition. • The conductivity of N-graphene layer depends on the tickness. • Support of platinum shows efficient electrocatalytic performance for biosensor. • CV curves and amperometric responses improved and optimized in the presence of N-graphene. - Abstract: An efficient non-enzymatic biosensor electrode consisting of nitrogen-doped graphene (N-graphene) and platinum nanoflower (Pt NF) with different N-graphene loadings were fabricated on indium tin oxide (ITO) glass using a simple layer-by-layer electrophoretic and electrochemical sequential deposition approach. N-graphene was synthesized by annealing graphene oxide with urea at 900 °C. The structure and morphology of the as-fabricated non-enzymatic biosensor electrodes were determined using X-ray diffraction, field emission electron microscopy, transmission electron microscopy, Raman and X-ray photoelectron spectra. The as-fabricated Pt NF-N-graphene-modified ITO electrodes with different N-graphene loadings were utilized as a non-enzymatic biosensor electrode for the detection of hydrogen peroxide (H_2O_2). The behaviors of the hybrid electrodes towards H_2O_2 reduction were assessed using chronoamperometry, cyclic voltammetry and electrochemical impedance spectroscopy analysis. The Pt NF-N-graphene-modified ITO electrode with a 0.05 mg ml"−"1 N-graphene loading exhibited the lowest detection limit, fastest amperometric sensing, a wide linear response range, excellent stability and reproducibility for the non-enzymatic H_2O_2 detection, due to the synergistic effect between the electrocatalytic activity of the Pt NF and the high conductivity and large surface area of N-graphene.

  4. Oxygen reduction at platinum nanoparticles supported on carbon cryogel in alkaline solution

    Directory of Open Access Journals (Sweden)

    N. R. ELEZOVIC

    2007-07-01

    Full Text Available The oxygen reduction reaction was investigated in 0.1 M NaOH solution, on a porous coated electrode formed of Pt particles supported on carbon cryogel. The Pt/C catalyst was characterized by the X-ray diffraction (XRD, transmission electron microscopy (TEM and cyclic voltammetry techniques. The results demonstrated a successful reduction of Pt to metallic form and homogenous Pt particle size distribution with a mean particle size of about 2.7 nm. The ORR kinetics was investigated by linear sweep polarization at a rotating disc electrode. The results showed the existence of two E – log j regions, usually referred to polycrystalline Pt in acid and alkaline solution. At low current densities (lcd, the Tafel slope was found to be close to –2.3RT/F, while at high current densities (hcd it was found to be close to –2×2.3RT/F. It is proposed that the main path in the ORR mechanism on Pt particles was the direct four-electron process, with the transfer of the first electron as the rate determining step. If the activities are expressed through the specific current densities, a small enhancement of the catalytic activity for Pt/C was observed compared to that of polycrystalline Pt. The effect of the Pt particle size on the electrocatalysis of oxygen reduction was ascribed to the predominant (111 facets of the platinum crystallites.

  5. An electrochemical study on the positive electrode side of the zinc–cerium hybrid redox flow battery

    International Nuclear Information System (INIS)

    Nikiforidis, Georgios; Berlouis, Léonard; Hall, David; Hodgson, David

    2014-01-01

    Highlights: •Elevated temperatures favoured the Ce 3+/4+ reaction on the Pt, Pt–Ir and carbon substrates. •j o increased with temperature over the range 25 °C to 60 °C for all substrates. •Non-porous carbon substrates showed higher reversibility on the Ce 3+/4+ reaction. •Surface degradation of the carbon electrodes occurred due to the high positive potentials. •The Pt–Ir coatings gave the largest j o at 60 °C and appear best suited for use as the positive electrode in the Zn–Ce RFB. -- Abstract: In this study, the electrochemical behaviour of the Ce 3+/4+ redox couple in methanesulfonic acid medium on various electrode substrates was investigated as a function of temperature. Carbon composite electrodes as well as platinum and platinum iridium coated electrodes were studied for their suitability in carrying out the Ce 3+/4+ redox reaction. Cyclic voltammetry in 0.8 mol dm −3 cerium and 4.5 mol dm −3 methanesulfonic acid solution showed that elevated temperatures favoured the Ce 3+ /Ce 4+ reaction on the various platinum and platinum–iridium coated substrates as well as on carbon composite surfaces. The latter electrodes showed better kinetics than the metal coatings but deteriorated badly under the high positive potentials required for the cerium reaction. The exchange current density (j o ), obtained through Tafel extrapolation, polarisation resistance and electrochemical impedance spectroscopy measurements, increased with temperature over the range 25 °C to 60 °C. The Pt–Ir coatings gave the largest j o at 60 °C and appear best suited for use as the positive electrode in the Zn–Ce redox flow battery

  6. Electrochemical properties and electrochemical impedance spectroscopy of polypyrrole-coated platinum electrodes

    Directory of Open Access Journals (Sweden)

    M. Fall

    2006-12-01

    Full Text Available Polypyrrole (PPy films of different thickness were characterized by electrochemical impedance spectroscopy (EIS measurements in acetonitrile and aqueous solutions, containing 0.1 M NaClO4 or sodium dodecylsulfate as the dopant. The PPy films were electrochemically deposited on Pt, and their electrochemical properties studied by cyclic voltammetry. Impedance spectra were obtained at potentials ranging from 0 to 0.8 V/SCE. The EIS data were fitted using two different equivalent electrical circuits (depending on the nature of the dopant. They involve a diffusive capacitance, which increased with the passing charge during electrosynthesis (i.e. film thickness for ClO4--doped PPy, but was practically unaffected by the film thickness in the case of SDS-doped PPy. Also, a double-layer capacitance was found only in the circuit of ClO4--doped PPy. It increased with the film thickness, and showed a minimum near the open-circuit potential. Finally the charge-transfer resistance (Rct obtained with SDS is nearly 200-fold higher than that obtained with ClO4- in the same solvent (H2O. With the same dopant (ClO4-, Rct is about five times higher in acetonitrile relative to water. All these EIS results of the different types of PPy suggest a relation with the wettability of the polymer.

  7. Electrochemical processes of adsorbed chlorobenzene and fluorobenzene on a platinum polycrystalline electrode

    Czech Academy of Sciences Publication Activity Database

    Kebrlová, Natálie; Janderka, P.; Trnková, L.

    2009-01-01

    Roč. 74, č. 4 (2009), s. 611-625 ISSN 0010-0765 Institutional research plan: CEZ:AV0Z40500505 Keywords : electrochemical degradation * hydrogenation * dehalogenation Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.856, year: 2009

  8. Cadmium poisoning of oxygen reduction on platinum electrode in potassium hydroxide

    Science.gov (United States)

    Miller, R. O.

    1972-01-01

    Experiment with a rotating disk and ring apparatus showed no poisoning by cadmium in 8.5 M KOH, alone or with Cl(-) or CO3(=). Poisoning does not occur either in 0.1 M KOH supernatant at CdO, but a partially reversible poisoning results from .0001 M CdCl2 and traces of fatty acid are present. Evidence indicates that the catastrophic poisoning affects the four-electron O2 reduction more than it does the one-electron H3O(+) discharge.

  9. Ellipsometry and LIMM investigations of the interaction between PZT thin films and platinum electrodes and air

    Czech Academy of Sciences Publication Activity Database

    Deineka, Alexander; Glinchuk, M. D.; Jastrabík, Lubomír; Suchaneck, G.; Sandner, T.; Gerlach, G.

    2001-01-01

    Roč. 254, - (2001), s. 205-211 ISSN 0015-0193 R&D Projects: GA ČR GA202/00/1425 Institutional research plan: CEZ:AV0Z1010914 Keywords : ferroelecric film * depth profile * interface interaction Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.471, year: 2001

  10. Electrical Discharge Platinum Machining Optimization Using Stefan Problem Solutions

    Directory of Open Access Journals (Sweden)

    I. B. Stavitskiy

    2015-01-01

    Full Text Available The article presents the theoretical study results of platinum workability by electrical discharge machining (EDM, based on the solution of the thermal problem of moving the boundary of material change phase, i.e. Stefan problem. The problem solution enables defining the surface melt penetration of the material under the heat flow proceeding from the time of its action and the physical properties of the processed material. To determine the rational EDM operating conditions of platinum the article suggests relating its workability with machinability of materials, for which the rational EDM operating conditions are, currently, defined. It is shown that at low densities of the heat flow corresponding to the finishing EDM operating conditions, the processing conditions used for steel 45 are appropriate for platinum machining; with EDM at higher heat flow densities (e.g. 50 GW / m2 for this purpose copper processing conditions are used; at the high heat flow densities corresponding to heavy roughing EDM it is reasonable to use tungsten processing conditions. The article also represents how the minimum width of the current pulses, at which platinum starts melting and, accordingly, the EDM process becomes possible, depends on the heat flow density. It is shown that the processing of platinum is expedient at a pulse width corresponding to the values, called the effective pulse width. Exceeding these values does not lead to a substantial increase in removal of material per pulse, but considerably reduces the maximum repetition rate and therefore, the EDM capacity. The paper shows the effective pulse width versus the heat flow density. It also presents the dependences of the maximum platinum surface melt penetration and the corresponding pulse width on the heat flow density. Results obtained using solutions of the Stephen heat problem can be used to optimize EDM operating conditions of platinum machining.

  11. Superlattices of platinum and palladium nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    MARTIN,JAMES E.; WILCOXON,JESS P.; ODINEK,JUDY G.; PROVENCIO,PAULA P.

    2000-04-06

    The authors have used a nonionic inverse micelle synthesis technique to form nanoclusters of platinum and palladium. These nanoclusters can be rendered hydrophobic or hydrophilic by the appropriate choice of capping ligand. Unlike Au nanoclusters, Pt nanoclusters show great stability with thiol ligands in aqueous media. Alkane thiols, with alkane chains ranging from C{sub 6} to C{sub 18} were used as hydrophobic ligands, and with some of these they were able to form 2-D and/or 3-D superlattices of Pt nanoclusters as small as 2.7 nm in diameter. Image processing techniques were developed to reliably extract from transmission electron micrographs (TEMs) the particle size distribution, and information about the superlattice domains and their boundaries. The latter permits one to compute the intradomain vector pair correlation function of the particle centers, from which they can accurately determine the lattice spacing and the coherent domain size. From these data the gap between the particles in the coherent domains can be determined as a function of the thiol chain length. It is found that as the thiol chain length increases, the gaps between particles within superlattice domains increases, but more slowly than one might expect, possibly indicating thiol chain interdigitation.

  12. Development of radioactive platinum group metal catalysts

    International Nuclear Information System (INIS)

    Chung, H.S.; Kim, Y.S.; Kim, Y.E.

    1999-03-01

    The fission product nuclides generated during the irradiation of reactor fuel include many useful elements, among them platinum group metals such as ruthenium, rhodium and palladium which are of great industrial importance, occur rarely in nature and are highly valuable. In this research, the authors reviewed various PGM recovery methods. Recovery of palladium from seven-component simulated waste solutions was conducted by selective precipitation method. The recovery yield was more than 99.5% and the purity of the product was more than 99%. Wet-proof catalyst was prepared with the recovered palladium. The specific surface area of the catalyst support was more than 400m 2 /g. The content of palladium impregnated on the support was 1 to 10 wt. %. Hydrogen isotope exchange efficiency of more than 93% to equilibrium with small amount of the catalyst was obtained. It was turned out possible to consider using such palladium or other very low active PGM materials in applications where its activity is unimportant as in nuclear industries. (author). 86 refs., 44 tabs., 88 figs

  13. Development of radioactive platinum group metal catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Chung, H.S.; Kim, Y.S.; Kim, Y.E. [and others

    1999-03-01

    The fission product nuclides generated during the irradiation of reactor fuel include many useful elements, among them platinum group metals such as ruthenium, rhodium and palladium which are of great industrial importance, occur rarely in nature and are highly valuable. In this research, the authors reviewed various PGM recovery methods. Recovery of palladium from seven-component simulated waste solutions was conducted by selective precipitation method. The recovery yield was more than 99.5% and the purity of the product was more than 99%. Wet-proof catalyst was prepared with the recovered palladium. The specific surface area of the catalyst support was more than 400m{sup 2}/g.The content of palladium impregnated on the support was 1 to 10 wt. %. Hydrogen isotope exchange efficiency of more than 93% to equilibrium with small amount of the catalyst was obtained. It was turned out possible to consider using such palladium or other very low active PGM materials in applications where its activity is unimportant as in nuclear industries. (author). 86 refs., 44 tabs., 88 figs.

  14. Transformation of medical grade silicone rubber under Nd:YAG and excimer laser irradiation: First step towards a new miniaturized nerve electrode fabrication process

    International Nuclear Information System (INIS)

    Dupas-Bruzek, C.; Robbe, O.; Addad, A.; Turrell, S.; Derozier, D.

    2009-01-01

    Medical grade silicone rubber, poly-dimethylsiloxane (PDMS) is a widely used biomaterial. Like for many polymers, its surface can be modified in order to change one or several of its properties which further allow this surface to be functionalized. Laser-induced surface modification of PDMS under ambient conditions is an easy and powerful method for the surface modification of PDMS without altering its bulk properties. In particular, we profit from both UV laser inducing surface modification and of UV laser micromachining to develop a first part of a new process aiming at increasing the number of contacts and tracks within the same electrode surface to improve the nerve selectivity of implantable self sizing spiral cuff electrodes. The second and last part of the process is to further immerse the engraved electrode in an autocatalytic Pt bath leading in a selective Pt metallization of the laser irradiated tracks and contacts and thus to a functionalized PDMS surface. In the present work, we describe the different physical and chemical transformations of a medical grade PDMS as a function of the UV laser and of the irradiation conditions used. We show that the ablation depths, chemical composition, structure and morphology vary with (i) the laser wavelength (using an excimer laser at 248 nm and a frequency-quadrupled Nd:YAG laser at 266 nm), (ii) the conditions of irradiation and (iii) the pulse duration. These different modified properties are expected to have a strong influence on the nucleation and growth rates of platinum which govern the adhesion and the thickness of the Pt layer on the electrodes and thus the DC resistance of tracks.

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

    Science.gov (United States)

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

    2014-08-22

    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.

  16. BOWIEITE: A NEW RHODIUM-IRIDIUM-PLATINUM SULFIDE IN PLATINUM-ALLOY NUGGETS, GOODNEWS BAY, ALASKA.

    Science.gov (United States)

    Desborough, George A.; Criddle, Alan J.

    1984-01-01

    Bowieite (Rh,Ir,Pt)//2S//3, a new mineral species, is found in three nuggets of platinum from Goodnews Bay, Alaska. In linearly polarized reflected light, and compared to the host, higher reflecting white platinum-iridium alloy, bowieite is pale gray to pale gray-brown; neither bireflectance nor reflectance pleochroism is apparent. With polars crossed, its anisotropic rotation tints vary from gray to dark brown. Luminance values (relative to the CIE illuminant C) for R//1 and R//2, computed from full spectral data for the most bireflectant grain, are 45. 8% and 48. 2% in air, and 30. 5% and 33. 0% in oil, respectively. VHN//1//0//0 1288 (858 to 1635). Bowieite is orthorhombic, space group Pnca, with a 8. 454(7) -8. 473(8), b 5. 995(1)-6. 002(7), c 6. 143(1)-6. 121(8) A, Z equals 4. Some grains that are 2. 6 to 3. 8 atomic % metal-deficient occur as an optically coherent rim on bowieite; the rim and the bowieite grain are not optically continuous.

  17. Synthesis of platinum nanowire networks using a soft template.

    Science.gov (United States)

    Song, Yujiang; Garcia, Robert M; Dorin, Rachel M; Wang, Haorong; Qiu, Yan; Coker, Eric N; Steen, William A; Miller, James E; Shelnutt, John A

    2007-12-01

    Platinum nanowire networks have been synthesized by chemical reduction of a platinum complex using sodium borohydride in the presence of a soft template formed by cetyltrimethylammonium bromide in a two-phase water-chloroform system. The interconnected polycrystalline nanowires possess the highest surface area (53 +/- 1 m2/g) and electroactive surface area (32.4 +/- 3.6 m2/g) reported for unsupported platinum nanomaterials; the high surface area results from the small average diameter of the nanowires (2.2 nm) and the 2-10 nm pores determined by nitrogen adsorption measurements. Synthetic control over the network was achieved simply by varying the stirring rate and reagent concentrations, in some cases leading to other types of nanostructures including wormlike platinum nanoparticles. Similarly, substitution of a palladium complex for platinum gives palladium nanowire networks. A mechanism of formation of the metal nanowire networks is proposed based on confined metal growth within a soft template consisting of a network of swollen inverse wormlike micelles.

  18. Structures of 38-atom gold-platinum nanoalloy clusters

    Energy Technology Data Exchange (ETDEWEB)

    Ong, Yee Pin; Yoon, Tiem Leong [School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Lim, Thong Leng [Faculty of Engineering and Technology, Multimedia University, Melaka Campus, 75450 Melaka (Malaysia)

    2015-04-24

    Bimetallic nanoclusters, such as gold-platinum nanoclusters, are nanomaterials promising wide range of applications. We perform a numerical study of 38-atom gold-platinum nanoalloy clusters, Au{sub n}Pt{sub 38−n} (0 ≤ n ≤ 38), to elucidate the geometrical structures of these clusters. The lowest-energy structures of these bimetallic nanoclusters at the semi-empirical level are obtained via a global-minimum search algorithm known as parallel tempering multi-canonical basin hopping plus genetic algorithm (PTMBHGA), in which empirical Gupta many-body potential is used to describe the inter-atomic interactions among the constituent atoms. The structures of gold-platinum nanoalloy clusters are predicted to be core-shell segregated nanoclusters. Gold atoms are observed to preferentially occupy the surface of the clusters, while platinum atoms tend to occupy the core due to the slightly smaller atomic radius of platinum as compared to gold’s. The evolution of the geometrical structure of 38-atom Au-Pt clusters displays striking similarity with that of 38-atom Au-Cu nanoalloy clusters as reported in the literature.

  19. Microscopical characterization of carbon materials derived from coal and petroleum and their interaction phenomena in making steel electrodes, anodes and cathode blocks for the Microscopy of Carbon Materials Working Group of the ICCP

    Science.gov (United States)

    Predeanu, G.; Panaitescu, C.; Bălănescu, M.; Bieg, G.; Borrego, A.G.; Diez, M. A.; Hackley, Paul C.; Kwiecińska, B.; Marques, M.; Mastalerz, Maria; Misz-Kennan, M.; Pusz, S.; Suarez-Ruiz, I.; Rodrigues, S.; Singh, A. K.; Varma, A. K.; Zdravkov, A.; Zivotić, D.

    2015-01-01

    This paper describes the evaluation of petrographic textures representing the structural organization of the organic matter derived from coal and petroleum and their interaction phenomena in the making of steel electrodes, anodes and cathode blocks.This work represents the results of the Microscopy of Carbon Materials Working Group in Commission III of the International Committee for Coal and Organic Petrology between the years 2009 and 2013. The round robin exercises were run on photomicrograph samples. For textural characterization of carbon materials the existing ASTM classification system for metallurgical coke was applied.These round robin exercises involved 15 active participants from 12 laboratories who were asked to assess the coal and petroleum based carbons and to identify the morphological differences, as optical texture (isotropic/anisotropic), optical type (punctiform, mosaic, fibre, ribbon, domain), and size. Four sets of digital black and white microphotographs comprising 151 photos containing 372 fields of different types of organic matter were examined. Based on the unique ability of carbon to form a wide range of textures, the results showed an increased number of carbon occurrences which have crucial role in the chosen industrial applications.The statistical method used to evaluate the results was based on the “raw agreement indices”. It gave a new and original view on the analysts' opinion by not only counting the correct answers, but also all of the knowledge and experience of the participants. Comparative analyses of the average values of the level of overall agreement performed by each analyst in the exercises during 2009–2013 showed a great homogeneity in the results, the mean value being 90.36%, with a minimum value of 83% and a maximum value of 95%.

  20. Potentiometric titration of molybdenum (6) with a cathode-polarized solid electrode

    International Nuclear Information System (INIS)

    Boeva, L.V.; Kimstach, V.A.; Bagdasarov, K.N.

    1980-01-01

    The possibility has been studied of using solid electrodes for potentiometric precipitation titration of molybdenum (6). A cathode-polarized electrode, electrochemically covered with a molybdenum blue layer, can be used as indicator electrode. The best results were obtained during deposition of molybdenum blue on a tungsten electrode. The mechanism of electrode work during titration has been investigated. A procedure has been developed of titration of molybdenum (6) in acid solutions using hydroxylamine N-aryl derivatives as titrants

  1. The development of platinum-based alloys and their thermodynamic database

    OpenAIRE

    Cornish L.A.; Hohls J.; Hill P.J.; Prins S.; Süss R.; Compton D.N.

    2002-01-01

    A series of quaternary platinum-based alloys have been demonstrated to exhibit the same two-phase structure as Ni-based superalloys and showed good mechanical properties. The properties of ternary alloys were a good indication that the quaternary alloys, with their better microstructure, will be even better. The quaternary alloy composition has been optimised at Pt84:Al11:Ru2:Cr3 for the best microstructure and hardness. Work has begun on establishing a thermodynamic database for Pt-Al-Ru-Cr ...

  2. Effect of temperature on the electro-oxidation of ethanol on platinum

    Directory of Open Access Journals (Sweden)

    Ana Paula M. Camargo

    2010-01-01

    Full Text Available We present in this work an experimental investigation of the effect of temperature (from 25 to 180 ºC in the electro-oxidation of ethanol on platinum in two different phosphoric acid concentrations. We observed that the onset potential for ethanol electro-oxidation shifts to lower values and the reaction rates increase as temperature is increased for both electrolytes. The results were rationalized in terms of the effect of temperature on the adsorption of reaction intermediates, poisons, and anions. The formation of oxygenated species at high potentials, mainly in the more diluted electrolyte, also contributes to increase the electro-oxidation reaction rate.

  3. Punica granatum fabricated platinum nanoparticles: A therapeutic pill for breast cancer

    Science.gov (United States)

    Jha, Babita; Rao, Mugdha; Chattopadhyay, A.; Bandyopadhyay, A.; Prasad, K.; Jha, Anal K.

    2018-05-01

    The current research highlights the fabrication of biocompatible platinum nanoparticles (Pt NPs) in first hand from arils of Punica granatum by using green chemistry approach. Formation of Pt NPs was determined by UV-visible, X-ray diffraction, and FTIR techniques. The anti-cancer potential of fabricated Pt NPs was evaluated by MTT assay on MCF7 and MDA-MB-231 breast cancer cell lines. This work is foreshadowing the prospect of Pt NPs application as a therapeutic drug for cancer treatment.

  4. Electrode Nanostructures in Lithium‐Based Batteries

    Science.gov (United States)

    Mahmood, Nasir

    2014-01-01

    Lithium‐based batteries possessing energy densities much higher than those of the conventional batteries belong to the most promising class of future energy devices. However, there are some fundamental issues related to their electrodes which are big roadblocks in their applications to electric vehicles (EVs). Nanochemistry has advantageous roles to overcome these problems by defining new nanostructures of electrode materials. This review article will highlight the challenges associated with these chemistries both to bring high performance and longevity upon considering the working principles of the various types of lithium‐based (Li‐ion, Li‐air and Li‐S) batteries. Further, the review discusses the advantages and challenges of nanomaterials in nanostructured electrodes of lithium‐based batteries, concerns with lithium metal anode and the recent advancement in electrode nanostructures. PMID:27980896

  5. The effect of loading and particle size on the oxygen reaction in CGO impregnated Pt electrodes

    DEFF Research Database (Denmark)

    Lund, Anders; Hansen, Karin Vels; Jacobsen, Torben

    2012-01-01

    Porous platinum electrodes impregnated with Gd x Ce1−x O2−δ (CGO) are investigated to characterise how nano-sized CGO grains affect the oxygen reaction. Impedance measurements were performed at temperatures between 450 and 750 °C and at oxygen partial pressures of 0.2 and 5 × 10−5 bar for electro......Porous platinum electrodes impregnated with Gd x Ce1−x O2−δ (CGO) are investigated to characterise how nano-sized CGO grains affect the oxygen reaction. Impedance measurements were performed at temperatures between 450 and 750 °C and at oxygen partial pressures of 0.2 and 5 × 10−5 bar...... for electrodes with various CGO loadings and electrodes annealed at various temperatures. The morphology was characterised by scanning electron microscopy and the CGO grain size was determined from X-ray diffraction peak broadening. The results showed that the polarisation resistance decreased with increasing...

  6. Electrode-electrolyte interface model of tripolar concentric ring electrode and electrode paste.

    Science.gov (United States)

    Nasrollaholhosseini, Seyed Hadi; Steele, Preston; Besio, Walter G

    2016-08-01

    Electrodes are used to transform ionic currents to electrical currents in biological systems. Modeling the electrode-electrolyte interface could help to optimize the performance of the electrode interface to achieve higher signal to noise ratios. There are previous reports of accurate models for single-element biomedical electrodes. In this paper we develop a model for the electrode-electrolyte interface for tripolar concentric ring electrodes (TCRE) that are used to record brain signals.

  7. Phosphate-mediated electrochemical adsorption of cisplatin on gold electrodes

    International Nuclear Information System (INIS)

    Kolodziej, Adam; Figueiredo, Marta C.; Koper, Marc T.M.; Fernandez-Trillo, Francisco; Rodriguez, Paramaconi

    2017-01-01

    Highlights: •The potential-dependent adsorption and deposition of cisplatin on polycrystalline gold electrode is mediated by the adsorption of phosphate anions on gold electrode. •Quantitative analysis suggests that the stoichiometry of the phosphate species and the cisplatin adsorbed was 1:1. •Upon reduction of the phosphate-mediated cisplatin adsorption, the platinum deposits are formed by 3D nanoclusters -- Abstract: This manuscript reports the potential-dependent adsorption and deposition of cisplatin on polycrystalline gold electrode. It was found that this process is mediated by the adsorption of phosphate anions on the gold electrode and that the maximum coverage of Pt adsorbed is given by the maximum coverage of phosphate adsorbed at a given potential. The interaction of cisplatin with the phosphate groups was confirmed by in situ FTIR spectroscopy under external reflexion configuration. Quantitative analysis suggests that the stoichiometry of the phosphate species and the cisplatin adsorbed was 1:1. Moreover, the relationship between the charge of the Pt deposited and the charge of the electrochemical surface area of the Pt deposited on the gold electrodes indicates that 3D nanoclusters of a few atoms of Pt were formed over the gold electrode upon the electrochemical reduction of the adsorbed cisplatin. The Pt nanoclusters formed under these conditions were later evaluated for the oxidation of a monolayer of carbon monoxide. The Pt nanoclusters showed a high overpotential for the oxidation of the carbon monoxide monolayer and the high oxidation overpotential was attributed to the absence of adsorption sites for OH species on the Pt clusters: only at potentials where the OH species are adsorbed at the edge between the Pt nanocluster and the gold support, the oxidation of the carbon monoxide on the Pt nanoparticles takes place.

  8. PEEM microscopy and DFT calculations of catalytically active platinum surfaces and interfaces

    International Nuclear Information System (INIS)

    Spiel, C.

    2012-01-01

    The aim of this thesis was to investigate the properties of catalytically active platinum surfaces and interfaces both with experimental and theoretical methods. Using experimental methods, catalytic CO oxidation on individual grains of a polycrystalline platinum foil was studied in situ under high vacuum (HV) conditions. A polycrystalline platinum foil consists of individual µm-sized crystal grains that are mainly [100]-, [110]- and [111]-oriented and differ significantly in their catalytic activity. In order to elucidate the differences existing between the reactivity of the individual grains, a combination of photoemission electron microscopy (PEEM) and quadrupole mass spectrometry (QMS) was used in this work. The working principle of PEEM is based on the photoelectric effect where illumination of the sample with (UV-)light causes emission of photoelectrons. The emitted photoelectrons are used to visualize the sample surface (with typical resolution in the low micrometer range). The PEEM image contrast originates from differences in the local work function that may arise due to different crystallographic orientations and/or changes in the adsorbate coverage. With a combination of PEEM and QMS, it was possible to study the kinetics of catalytic CO oxidation on polycrystalline platinum foil both in a global and a laterally-resolved way simultaneously. If catalytic CO oxidation on surfaces of platinum is followed at constant temperature and oxygen partial pressure under cyclic variation of the CO pressure, a hysteresis in the CO2 production rate is observed in the bistability region with two noticeable kinetic transitions (called tA and tB) taking place at different CO pressures when the catalyst surface switches back-and-forth between two steady states of high and low reactivity while the Pt-surface is, correspondingly, either oxygen- or CO-covered. In the bistability region between τ A and τ B , the system stays (at the same values of the external parameters p

  9. ELECTROD FLUOR-SELECTIV

    Directory of Open Access Journals (Sweden)

    Mariana DÎRU

    2018-03-01

    Full Text Available A fost preparat un senzor anionic specific, bazat pe pivalatul trinuclear al cromului(III ca material electro­activ încorporat în membrana PVC plastifiată. Senzorul prezintă răspuns Nernstian (55,78 mV/decadă în intervalul de concentrație 10-1-10-4 mol/L cu limita de detecție 2,0∙10-5 mol/L pentru anionul fluorură. Domeniul optim de pH de funcţionare a electrodului asamblat este ˃5. Senzorul dat are un timp de răspuns de 30-60 s și reproductibilitatea rezultatelor se menține timp de 3 luni. Coeficienții potențiometrici ai selectivității au fost determinați prin metoda soluțiilor separate. A fost realizată aplicarea acestor electrozi la analiza pastei de dinți ce conține fluorură și rezultatele experimentale au fost comparate cu datele de pe prospect.FLUORIDE-SELECTIVE ELECTRODEA specific anionic sensor has been prepared, based on trinuclearchromium(III pivalate as sensing material incorpo­rated into the plasticized PVC-membrane. The sensor exhibited Nernstian response (55,78 mV/decade in the region between 10-1-10-4 mol/L with a detection limit of 2,0∙10-5 mol/L for fluoride. The working pH of the electrode was in the 5-6 range. The sensor has a response time 30-60 s and can be used for least 3 month. The potentiometric selectivity coefficients were determined by separate solution method. Application of these electrodes to the analysis of toothpaste containing fluoride has been realized and experimental results have been compared with the data on the prospectus.

  10. Modification of the ultrasound induced activity by the presence of an electrode in a sono-reactor working at two low frequencies (20 and 40 kHz). Part II: Mapping flow velocities by particle image velocimetry (PIV).

    Science.gov (United States)

    Mandroyan, A; Doche, M L; Hihn, J Y; Viennet, R; Bailly, Y; Simonin, L

    2009-01-01

    Sonoelectrochemical experiments differ from sonochemical ones by the introduction of electrodes in the sonicated reaction vessel. The aim of the study is to characterize the changes in the ultrasonic activity induced by the presence of an electrode located in front of the transducer. The scope of our investigations concerns two low frequency vibration modes: 20 and 40 kHz. For this purpose, two laser visualization techniques have been used. The first part of the study, described in a previous paper (Part I), deals with the laser tomography technique which provides an accurate picture of the reactor active zones, related to numerous cavitation events. The second part of the paper (Part II) will describe the particle image velocimetry (PIV) technique used to measure the velocity vector field in the fluid portion between the horn and the electrode. As for the previous study, two parameters were studied: the electrical power supplied to the transducer and the electrode/transducer distance. The velocity vector fields show a main flow in the reactor axis. This flow seems to correspond to the conical cavitation bubbles structure which is observed on the laser tomography pictures. When an electrode is introduced into the reactor, two additional symmetric transversal flows can be quantified on both sides of the electrode.

  11. Flow Injection Analysis with Electrochemical Detection for Rapid Identification of Platinum-Based Cytostatics and Platinum Chlorides in Water

    Directory of Open Access Journals (Sweden)

    Marketa Kominkova

    2014-02-01

    Full Text Available Platinum-based cytostatics, such as cisplatin, carboplatin or oxaliplatin are widely used agents in the treatment of various types of tumors. Large amounts of these drugs are excreted through the urine of patients into wastewaters in unmetabolised forms. This phenomenon leads to increased amounts of platinum ions in the water environment. The impacts of these pollutants on the water ecosystem are not sufficiently investigated as well as their content in water sources. In order to facilitate the detection of various types of platinum, we have developed a new, rapid, screening flow injection analysis method with electrochemical detection (FIA-ED. Our method, based on monitoring of the changes in electrochemical behavior of analytes, maintained by various pH buffers (Britton-Robinson and phosphate buffer and potential changes (1,000, 1,100 and 1,200 mV offers rapid and cheap selective determination of platinum-based cytostatics and platinum chlorides, which can also be present as contaminants in water environments.

  12. Niraparib Maintenance Therapy in Platinum-Sensitive, Recurrent Ovarian Cancer

    DEFF Research Database (Denmark)

    Mirza, Mansoor R; Monk, Bradley J; Herrstedt, Jørn

    2016-01-01

    Background Niraparib is an oral poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) 1/2 inhibitor that has shown clinical activity in patients with ovarian cancer. We sought to evaluate the efficacy of niraparib versus placebo as maintenance treatment for patients with platinum-sensitive, ......Background Niraparib is an oral poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) 1/2 inhibitor that has shown clinical activity in patients with ovarian cancer. We sought to evaluate the efficacy of niraparib versus placebo as maintenance treatment for patients with platinum...... or 4 adverse events that were reported in the niraparib group were thrombocytopenia (in 33.8%), anemia (in 25.3%), and neutropenia (in 19.6%), which were managed with dose modifications. Conclusions Among patients with platinum-sensitive, recurrent ovarian cancer, the median duration of progression...

  13. Cytotoxic evaluation upon cis-platinum aminodiacetic acid complexes

    International Nuclear Information System (INIS)

    Almah binti Awaluddin; Parsons, Peter G.; Lean, Jenny M.; Jacobs, Jeffrey J.

    1990-01-01

    Cytoxic study of cis-platinum aminodiacetic acid complexes. Three novel platinum complexes have been synthesised and characterised by Awaluddin et. al (1987). This introduces a new area of radiopharmaceuticals based on technician and platinum. Cytotoxic studies were conducted on these complexes using four different types of cell lines. The para amina was found to be highly active against multi-resistant ovarian tumor cells compared to normal cells (fibroblast) and other tumor cells. The chemical structure of para-amina appears to be devoid of any functional group resembling current antitumor drugs except for a distant similarity to metotrexate with respect to the p-aminobenzoic type structure. However cell lines such as Hela and MM 253c-1, which is sensitive to metotrexate, were not sensitive to the para amina. Preliminary studies have shown that cells are blocked in the G phase of the cell cycle, suggesting an antimetabolite effect

  14. Analysis of Factors Influencing Fur Quality in Minks of Standard, Pastel, Platinum and White Hedlunda Colour Strains

    OpenAIRE

    Stanisław Socha; Dorota Kołodziejczyk; Ewa Kondraciuk; Danuta Wójcik; Aldona Gontarz

    2010-01-01

    The work aimed at the analysis of the factors that influence conformation traits, included animal size and fur quality traits in four colour types of mink: standard, pastel, platinum and white Hedlunda. The data concerns the evaluation of animal conformation traits in the period of three years. The analysis of variance of particular traits indicates statistically significant effect of the year of birth, colour type and animal sex on the majority of analysed traits. Higher means of license eva...

  15. Genetically engineered bacteriophage delivers a tumor necrosis factor alpha antagonist coating on neural electrodes

    International Nuclear Information System (INIS)

    Kim, Young Jun; Nam, Chang-Hoon; Jin, Young-Hyun; Stieglitz, Thomas; Salieb-Beugelaar, Georgette B

    2014-01-01

    This paper reports a novel approach for the formation of anti-inflammatory surface coating on a neural electrode. The surface coating is realized using a recombinant f88 filamentous bacteriophage, which displays a short platinum binding motif and a tumor necrosis factor alpha antagonist (TNF-α antagonist) on p3 and p8 proteins, respectively. The recombinant bacteriophages are immobilized on the platinum surface by a simple dip coating process. The selective and stable immobilization of bacteriophages on a platinum electrode is confirmed by quartz crystal microbalance with dissipation monitoring, atomic force microscope and fluorescence microscope. From the in vitro cell viability test, the inflammatory cytokine (TNF-α) induced cell death was prevented by presenting recombinant bacteriophage coating, albeit with no significant cytotoxic effect. It is also observed that the bacteriophage coating does not have critical effects on the electrochemical properties such as impedance and charge storage capacities. Thus, this approach demonstrates a promising anti-apoptotic as well as anti-inflammatory surface coating for neural implant applications. (paper)

  16. Investigation of the direct and indirect electrochemical oxidation of hydrazine in nitric acid medium on platinum

    International Nuclear Information System (INIS)

    Cames, B.

    1997-01-01

    In nuclear fuel processing by the PUREX process, the purification of plutonium in nitric acid medium requires the oxidation of Pu(III) to Pu(IV), and of hydrazinium nitrate to nitrogen. The study helped to characterize the electrochemical behavior of the oxidation of hydrazinium nitrate and the reduction of nitric acid to nitrous acid, a compound which can chemically oxidize hydrazinium nitrate and Pu(III). Electro-analytical studies on polycrystalline platinum showed that hydrazine is oxidized in two potential zones, which depend on the surface texture of the platinum anode. Electrolysis in separate compartments, carried out in medium-acid media (2 and 4 mo/l) in the potential zone where these processes take place, showed that, at 0.9 V/ECS, the hydrazine oxidation reactions involved are: a four-electron process (75 %) with nitrogen formation and a one-electron process (25 %) with formation of nitrogen and ammonium ion. By contrast, electrolysis carried out at 0.65 V/ECS (with reactivation of the electrode at - 0.2 V/ECS to remove the poison from the platinum) allowed the selective oxidation of hydrazine to nitrogen by the four-electron reaction. Nitric acid can only be reduced to nitrous acid in the absence of hydrazine. For medium-acid media (≤ 6 mol/l), this reaction takes place at potentials below - 0.2 V/ECS. However, the production rate of nitrous acid (partial order 0 with respect to nitric acid) is very low compared with the values obtained for strongly-acid media (6 to 10 mol/l) at the potential of - 0.1 V/ECS. Note that, in concentrated nitric medium, the selectivity of the reduction reaction is 47 to 85 % for nitrous acid, depending on the nitric acid concentration (6 to 10 mol/l) and the potential imposed (- 0.1 ≤ E ≤ 0.6 V/ECS). A kinetic study helped to determine the hydrazine oxidation rates as a function of the operating conditions. In all cases, the reaction rate is of partial order 0 with respect to hydrazine. These studies accordingly

  17. Special aspects of the indirect radiotracer technique when used to study the adsorption and electrochemical reactions of organic substances at solid electrodes

    International Nuclear Information System (INIS)

    Andreev, V.N.; Horanyi, G.; Kazarinov, V.E.

    1986-01-01

    This paper analyzes the possibilities and special aspects of the indirect radiotracer technique with a number of examples. Data are presented concerning the effects of acetic and oxalic acid on chloride ion adsorption on platinized platinum electrodes at a potential E = 0.2 V. The effect on chloride ion adsorption is much larger in the case of oxalic acid, which is evidence for its higher adsorbability on platinum at E = 0.2 V. It is shown that the indirect radiotracer technique offers significant possibilities for studying the electrochemical properties of adsorption products of organic substances

  18. Activated graphene nanoplatelets as a counter electrode for dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Jiawei [Center for Advanced Photovoltaics, Department of Electrical Engineering, South Dakota State University, Brookings, South Dakota 57007 (United States); Department of Mechanical Engineering, North Dakota State University, Fargo, North Dakota 58102 (United States); Zhou, Zhengping; Qiao, Qiquan, E-mail: qiquan.qiao@sdstate.edu [Center for Advanced Photovoltaics, Department of Electrical Engineering, South Dakota State University, Brookings, South Dakota 57007 (United States); Sumathy, K. [Department of Mechanical Engineering, North Dakota State University, Fargo, North Dakota 58102 (United States); Yang, Huojun [Department of Construction Management and Engineering, North Dakota State University, Fargo, North Dakota 58102 (United States)

    2016-04-07

    Activated graphene nanoplatelets (aGNPs) prepared by a hydrothermal method using KOH as activating agent were used as counter electrode for high efficiency dye-sensitized solar cells (DSSCs). After the KOH activation, the scanning electron microscopy image shows that aGNPs demonstrate a more curled, rough, and porous morphology which could contain both micro- and mesopores. The KOH activation changed the stacked layers of GNPs to a more crumpled and curved morphology. The microstructure of large pores significantly increased the electrode surface area and roughness, leading to the high electrocatalytic activity for triiodide reduction at the counter electrode. The DSSCs fabricated using aGNP as counter electrodes were tested under standard AM 1.5 illumination with an intensity of 91.5 mW/cm{sup 2}. The device achieved an overall power conversion efficiency of 7.7%, which is comparable to the conventional platinum counter electrode (8%). Therefore, the low cost and high performance aGNP based counter electrode is a promising alternative to conventional Pt counter electrode in DSSCs.

  19. Sputter deposition on gas diffusion electrodes of Pt-Au nanoclusters for methanol oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Giorgi, L.; Giorgi, R.; Gagliardi, S.; Serra, E. [ENEA Casaccia Research Center, Rome (Italy). Physics Technologies and New Materials; Alvisi, M.; Signore, M.A. [ENEA Brindisi Research Center, Brindisi (Italy). Physics Technologies and New Materials

    2008-07-01

    Polymer electrolyte fuel cells (PEFCs) are suited for use in commercial electrical vehicle and electric power applications. The gas diffusion electrodes of PEFCs are catalyzed by the deposition of platinum (Pt) nanoparticles on carbon powder. The particles must be localized on the electrode surface in order to achieve high electrocatalyst utilization. This study discussed a method of preparing PEFC electrodes using sputter deposition of a Pt-gold (Au) alloy nanoparticles on carbon powders. The method was designed to improve electrode performance and catalyst utilization. The nano-sized alloy clusters were deposited on a gas diffusion electrode at room temperature. The deposits were then characterized using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) in order to examine the effect of the deposition technique on the nano-morphology and electrocatalytic performance of the electrode. Results of the study showed that the technique can be used in the large-scale manufacture of fuel cell electrodes. 3 refs., 1 fig.

  20. A novel fabrication method of carbon electrodes using 3D printing and chemical modification process.

    Science.gov (United States)

    Tian, Pan; Chen, Chaoyang; Hu, Jie; Qi, Jin; Wang, Qianghua; Chen, Jimmy Ching-Ming; Cavanaugh, John; Peng, Yinghong; Cheng, Mark Ming-Cheng

    2017-11-23

    Three-dimensional (3D) printing is an emerging technique in the field of biomedical engineering and electronics. This paper presents a novel biofabrication method of implantable carbon electrodes with several advantages including fast prototyping, patient-specific and miniaturization without expensive cleanroom. The method combines stereolithography in additive manufacturing and chemical modification processes to fabricate electrically conductive carbon electrodes. The stereolithography allows the structures to be 3D printed with very fine resolution and desired shapes. The resin is then chemically modified to carbon using pyrolysis to enhance electrochemical performance. The electrochemical characteristics of 3D printing carbon electrodes are assessed by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The specific capacitance of 3D printing carbon electrodes is much higher than the same sized platinum (Pt) electrode. In-vivo electromyography (EMG) recording, 3D printing carbon electrodes exhibit much higher signal-to-noise ratio (40.63 ± 7.73) than Pt electrodes (14.26 ± 6.83). The proposed biofabrication method is envisioned to enable 3D printing in many emerging applications in biomedical engineering and electronics.