Modeling of electrochemical hydrogen storage in metal hydride electrodes

NARCIS (Netherlands)

Ledovskikh, A.; Danilov, D.; Vermeulen, P.; Notten, P.H.L.

2010-01-01

The recently presented Electrochemical Kinetic Model (EKM), describing the electrochemical hydrogen storage in hydride-forming materials, has been extended by the description of the solid/electrolyte interface, i.e. the charge transfer kinetics and electrical double layer charging. A complete set of

An electrochemical hydrogen meter for measuring hydrogen in sodium using a ternary electrolyte mixture

CERN Document Server

Sridharan, R; Nagaraj, S; Gnanasekaran, T; Periaswami, G

2003-01-01

An electrochemical sensor for measuring hydrogen concentration in liquid sodium that is based on a ternary mixture of LiCl, CaCl sub 2 and CaHCl as the electrolyte has been developed. DSC experiments showed the eutectic temperature of this ternary system to be approx 725 K. Impedance spectroscopic analysis of the electrolyte indicated ionic conduction through a molten phase at approx 725 K. Two electrochemical hydrogen sensors were constructed using the ternary electrolyte of composition 70 mol% LiCl:16 mol% CaHCl:14 mol% CaCl sub 2 and tested at 723 K in a mini sodium loop and at hydrogen levels of 60-250 ppb in sodium. The sensors show linear response in this concentration range and are capable of detecting a change of 10 ppb hydrogen in sodium over a background level of 60 ppb. Identification of this electrolyte system and its use in a sensor for measuring hydrogen in sodium are described in this paper.

Correlations between electrochemical activity and heterogeneous catalysis for hydrogen dissociation on platinum

Energy Technology Data Exchange (ETDEWEB)

Ross, P N; Stonehart, P [Pratt and Whitney Aircraft, Middletown, Conn. (USA)

1975-02-01

Hydrogen-deuterium exchange rates on platinum surfaces have been compared to equivalent hydrogen molecule and adsorbed hydrogen atom electrochemical oxidation rates on the same surfaces. Over a temperature range of 293 to 360/sup 0/K the first order rate constants for H/sub 2/-D/sub 2/ exchange and hydrogen molecule electrochemical oxidation are the same, showing that the absorption-dissociation reaction (TAFEL, BONHOEFFER-FARKAS) is rate controlling. The rate of oxidation of the adsorbed hydrogen atom reaction involving electron transfer (VOLMER) is an order of magnitude larger.

Electrochemical Hydrogen Storage in Facile Synthesized Co@N-Doped Carbon Nanoparticle Composites.

Science.gov (United States)

Zhou, Lina; Qu, Xiaosheng; Zheng, Dong; Tang, Haolin; Liu, Dan; Qu, Deyang; Xie, ZhiZhong; Li, Junsheng; Qu, Deyu

2017-11-29

A Co@nitrogen-doped carbon nanoparticle composite was synthesized via a facile molecular self-assembling procedure. The material was used as the host for the electrochemical storage of hydrogen. The hydrogen storage capacity of the material was over 300 mAh g -1 at a rate of 100 mAg -1 . It also exhibited superior stability for storage of hydrogen, high rate capability, and good cyclic life. Hybridizing metallic cobalt nanoparticle with nitrogen-doped mesoporous carbon is found to be a good approach for the electrochemical storage of hydrogen.

High-vacuum pumping out of hydrogen isotopes by compressed and electrophysical pumps

International Nuclear Information System (INIS)

Bychkova, A.D.; Ershova, Z.V.; Saksaganskij, G.L.; Serebrennikov, D.V.

1982-01-01

To explain the selection of parameters of vacuum systems of projected thermonuclear devices, experiments are performed on the pumping-out of deuterium and tritium by high-vacuum pumps of different types. The values of the fast response of turbomolecular, diffusion vapour-mercury, magneto-discharge and titanium getter pumps in the operation pressure range are determined. The rate of sorption of hydrogen isotopes by non-spraying gas absorber of cial alloy depending on the amount of the gas absorbed and temperature, is measured. Gas current is determined by the pressure drop on the diagram of the known conductivity. Individual calibration of manometric converters for different gases using a mercury burette is performed preliminarily. The means of high-vacuum pumping-out that have been studied have the following values of fast response for tritium (relatively to protium): turbomolecular pump-0.95; evaporation getter pump-0.25; magneto-discharge pumps-0.65-0.9; cial alloy-0.1...0.5

Mechanism of the electrochemical hydrogen reaction on smooth tungsten carbide and tungsten electrodes

International Nuclear Information System (INIS)

Wiesener, K.; Winkler, E.; Schneider, W.

1985-01-01

The course of the electrochemical hydrogen reaction on smooth tungsten-carbide electrodes in hydrogen saturated 2.25 M H 2 SO 4 follows a electrochemical sorption-desorption mechanism in the potential range of -0.4 to +0.1 V. At potentials greater than +0.1 V the hydrogen oxidation is controlled by a preliminary chemical sorption step. Concluding from the similar behaviour of tungsten-carbide and tungsten electrodes after cathodic pretreatment, different tungsten oxides should be involved in the course of the hydrogen reaction on tungsten carbide electrodes. (author)

Photoproduction of Hydrogen by Decamethylruthenocene Combined with Electrochemical Recycling.

Science.gov (United States)

Rivier, Lucie; Peljo, Pekka; Vannay, Laurent A C; Gschwend, Grégoire C; Méndez, Manuel A; Corminboeuf, Clémence; Scanlon, Micheál D; Girault, Hubert H

2017-02-20

The photoinduced hydrogen evolution reaction (HER) by decamethylruthenocene, Cp 2 *Ru II (Cp*=C 5 Me 5 ), is reported. The use of a metallocene to photoproduce hydrogen is presented as an alternative strategy to reduce protons without involving an additional photosensitizer. The mechanism was investigated by (spectro)electrochemical and spectroscopic (UV/Vis and 1 H NMR) measurements. The photoactivated hydride involved was characterized spectroscopically and the resulting [Cp 2 *Ru III ] + species was electrochemically regenerated in situ on a fluorinated tin oxide electrode surface. A promising internal quantum yield of 25 % was obtained. Optimal experimental conditions- especially the use of weakly coordinating solvent and counterions-are discussed. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Defect studies of ZnO single crystals electrochemically doped with hydrogen

Science.gov (United States)

Čížek, J.; Žaludová, N.; Vlach, M.; Daniš, S.; Kuriplach, J.; Procházka, I.; Brauer, G.; Anwand, W.; Grambole, D.; Skorupa, W.; Gemma, R.; Kirchheim, R.; Pundt, A.

2008-03-01

Various defect studies of hydrothermally grown (0001) oriented ZnO crystals electrochemically doped with hydrogen are presented. The hydrogen content in the crystals is determined by nuclear reaction analysis and it is found that already 0.3at.% H exists in chemically bound form in the virgin ZnO crystals. A single positron lifetime of 182ps is detected in the virgin crystals and attributed to saturated positron trapping at Zn vacancies surrounded by hydrogen atoms. It is demonstrated that a very high amount of hydrogen (up to ˜30at.%) can be introduced into the crystals by electrochemical doping. More than half of this amount is chemically bound, i.e., incorporated into the ZnO crystal lattice. This drastic increase of the hydrogen concentration is of marginal impact on the measured positron lifetime, whereas a contribution of positrons annihilated by electrons belonging to O-H bonds formed in the hydrogen doped crystal is found in coincidence Doppler broadening spectra. The formation of hexagonal shape pyramids on the surface of the hydrogen doped crystals by optical microscopy is observed and discussed.

A study of the electrochemical hydrogenation of o-xylene in a PEM hydrogenation reactor

International Nuclear Information System (INIS)

Fonocho, R.; Gardner, C.L.; Ternan, M.

2012-01-01

In this study, we investigate the electrochemical hydrogenation of o-xylene in a proton exchange membrane hydrogenation reactor (PEMHR). The reactor was operated isothermally over the temperature range 20–68 °C and at a pressure of 1 atm in a semi-batch mode. Hydrogen was fed into the anode compartment and o-xylene into the cathode. The hydrogenation efficiency was investigated at different current densities and temperatures. Results obtained show that the hydrogenation efficiency increases with temperature but decreases with current density. At low current densities the hydrogenation efficiency approaches 100%. A zero dimensional model was used to fit the data and extract a rate constant for the hydrogenation reaction. The activation energy for this reaction was found to be 28 kJ/mole.

An electrochemical pumping system for on-chip gradient generation.

Science.gov (United States)

Xie, Jun; Miao, Yunan; Shih, Jason; He, Qing; Liu, Jun; Tai, Yu-Chong; Lee, Terry D

2004-07-01

Within the context of microfluidic systems, it has been difficult to devise pumping systems that can deliver adequate flow rates at high pressure for applications such as HPLC. An on-chip electrochemical pumping system based on electrolysis that offers certain advantages over designs that utilize electroosmotic driven flow has been fabricated and tested. The pump was fabricated on both silicon and glass substrates using photolithography. The electrolysis electrodes were formed from either platinum or gold, and SU8, an epoxy-based photoresist, was used to form the pump chambers. A glass cover plate and a poly(dimethylsiloxane) (PDMS) gasket were used to seal the chambers. Filling of the chambers was accomplished by using a syringe to inject liquid via filling ports, which were later sealed using a glass cover plate. The current supplied to the electrodes controlled the rate of gas formation and, thus, the resulting fluid flow rate. At low backpressures, flow rates >1 microL/min have been demonstrated using polymer electrospray nozzle, we have confirmed the successful generation of a solvent gradient via a mass spectrometer.

Solar pumped laser and its application to hydrogen production

International Nuclear Information System (INIS)

Imasaki, K.; Saiki, T.; Li, D.; Motokosi, S.; Nakatsuka, M.

2007-01-01

Solar pumped laser has been studied. Recently, a small ceramic laser pumped by pseudo solar light shows high efficiency of more than 40% which exceeds a solar cell. Such solar pumped laser can concentrate the large area of solar energy in a focused spot of small area. This fact implies the application of such laser for clean and future renewable energy source as hydrogen. For this purpose, 100 W level laboratory solar laser HELIOS is completed using disk ceramic active mirror laser to achieve high temperature. This laser is a kind of MOPA system. Oscillator of additional small laser is used. Laser light is generated in oscillator and is amplified in ceramic disks of solar pumped. The temperature from this system is to be more than 1500 K. We will use a simple graphite cavity for laser power absorption and to get a high temperature. We are also designing a 10 MW CW laser based on this technology. This may be expected an application of solar energy for hydrogen production with total efficiency of 30%

Capacitance-Assisted Sustainable Electrochemical Carbon Dioxide Mineralisation.

Science.gov (United States)

Lamb, Katie J; Dowsett, Mark R; Chatzipanagis, Konstantinos; Scullion, Zhan Wei; Kröger, Roland; Lee, James D; Aguiar, Pedro M; North, Michael; Parkin, Alison

2018-01-10

An electrochemical cell comprising a novel dual-component graphite and Earth-crust abundant metal anode, a hydrogen producing cathode and an aqueous sodium chloride electrolyte was constructed and used for carbon dioxide mineralisation. Under an atmosphere of 5 % carbon dioxide in nitrogen, the cell exhibited both capacitive and oxidative electrochemistry at the anode. The graphite acted as a supercapacitive reagent concentrator, pumping carbon dioxide into aqueous solution as hydrogen carbonate. Simultaneous oxidation of the anodic metal generated cations, which reacted with the hydrogen carbonate to give mineralised carbon dioxide. Whilst conventional electrochemical carbon dioxide reduction requires hydrogen, this cell generates hydrogen at the cathode. Carbon capture can be achieved in a highly sustainable manner using scrap metal within the anode, seawater as the electrolyte, an industrially relevant gas stream and a solar panel as an effective zero-carbon energy source. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

Stress distributions due to hydrogen concentrations in electrochemically charged and aged austenitic stainless steel

International Nuclear Information System (INIS)

Rozenak, P.; Loew, A.

2008-01-01

As a result of hydrogen concentration gradients in type austenitic stainless steels, formed during electrochemical charging and followed by hydrogen loss during aging, at room temperature, surface stresses were developed. These stresses were measured by X-ray technique and the crack formation thus induced could be studied using equilibrium stress equations. After various electrochemical charging and aging times, X-ray diffraction patterns obtained from samples indicated that the reflected and broadened diffraction peaks are the result of the formation of a non-uniform but continuous solid solution in the austenitic matrix. Since both hydrogen penetrations during charging and hydrogen release during aging are diffusion controlled processes and huge hydrogen concentration gradients in the thin surface layer, at depths comparable with the depth of X-ray penetration, are observed. The non-uniform hydrogen concentration in the austenitic matrix, results to the non-uniform expansion of the atomic microstructure and latter inevitably leads to the development of internal stresses. The internal stresses development formulae's are very similar to those relating to non-uniform heating of the materials, where thermal stresses appear due to non-uniform expansion or contraction. The relevant well developed theory is applicable in our case of non-uniform hydrogen concentrations in a solid solution of electrochemically charged and aged austenitic matrix. A few cracks were present on the surface after some minutes of electrochemical charging and the severity of cracking increased as hydrogen was lost during subsequent aging. This is consistent with the expectation of high compressive stresses in the bulk of the specimen during charging and high tensile surface stresses (at the level of 1 x 10 11 Pa) during the aging process. These stresses can induce the formation of surface cracks during the aging process after electrochemical charging in the AISI 316 stainless steel

Hydrogen pumping and release by graphite under high flux plasma bombardment

International Nuclear Information System (INIS)

Hirooka, Y.; Leung, W.K.; Conn, R.W.; Goebel, D.M.; LaBombard, B.; Nygren, R.; Wilson, K.L.

1988-01-01

Inert gas (helium or argon) plasma bombardment has been found to increase the surface gas adsorptivity of isotropic graphite (POCO-graphite), which can then getter residual gases in a high vacuum system. The inert gas plasma bombardment was carried out at a flux ≅ 1 x 10 18 ions s -1 cm -2 to a fluence of the order of 10 21 ions/cm 2 and at temperatures around 800 0 C. The gettering capability of graphite can be easily recovered by repeating inert gas plasma bombardment. The activated graphite surface exhibits a smooth, sponge-like morphology with significantly increased pore openings, which correlates with the observed increase in the surface gas adsorptivity. The activated graphite surface has been observed to pump hydrogen plasma particles as well. From calibrated H-alpha measurements, the dynamic hydrogen retention capacity is evaluated to be as large as 2 x 10 18 H/cm 2 at temperatures below 100 0 C and at a plasma bombarding energy of 300 eV. The graphite temperature was varied between 15 and 480 0 C. Due to the plasma particle pumping capability, hydrogen recycling from the activated graphite surface is significantly reduced, relative to that from a pre-saturated surface. A pre-saturated surface was also observed to reproducibly pump a hydrogen plasma to a concentration of 9.5 x 10 17 H/cm 2 . The hydrogen retention capacity of graphite is found to decrease with increasing temperature. A transient pumping mechanism associated with the sponge-like surface morphology is conjectured to explain the large hydrogen retention capacity. Hydrogen release behavior under helium and argon plasma bombardment was also investigated, and the result indicated the possibility of some in-pore retrapping effect. 43 refs., 11 figs

The permeation of hydrogen in a steel at elevated temperature by an electrochemical method

International Nuclear Information System (INIS)

Tsubakino, H.; Ando, A.; Yamakawa, K.

1984-01-01

An electrochemical permeation method has been widely used to study the transport characteristics of hydrogen in metals, i.e., the content, diffusivity and permeability. This electrochemical measurement technique has the following remarkable features: a good detection limit for the measurement of hydrogen content, a simpler measuring apparatus, suitability for successive measurement of the transport characteristics, and flexibility in variation of experimental conditions. However this method has been restricted to temperatures below 373 K because an aqueous solution has been used as an electrode. In this study, an electrochemical permeation method using molten salts at elevated temperatures (673-773 K) in the range of practical interest for hydrogen attack in steel is presented. The introduction of hydrogen by use of molten salts has been reported but it has been performed at 423473 K and at 553 K

Hydrogen Gas Recycling for Energy Efficient Ammonia Recovery in Electrochemical Systems

NARCIS (Netherlands)

Kuntke, Philipp; Rodríguez Arredondo, Mariana; Widyakristi, Laksminarastri; Heijne, ter Annemiek; Sleutels, Tom H.J.A.; Hamelers, Hubertus V.M.; Buisman, Cees J.N.

2017-01-01

Recycling of hydrogen gas (H₂) produced at the cathode to the anode in an electrochemical system allows for energy efficient TAN (Total Ammonia Nitrogen) recovery. Using a H₂ recycling electrochemical system (HRES) we achieved high TAN transport rates at low energy input. At

Heat pump cycle by hydrogen-absorbing alloys to assist high-temperature gas-cooled reactor in producing hydrogen

International Nuclear Information System (INIS)

Satoshi, Fukada; Nobutaka, Hayashi

2010-01-01

A chemical heat pump system using two hydrogen-absorbing alloys is proposed to utilise heat exhausted from a high-temperature source such as a high-temperature gas-cooled reactor (HTGR), more efficiently. The heat pump system is designed to produce H 2 based on the S-I cycle more efficiently. The overall system proposed here consists of HTGR, He gas turbines, chemical heat pumps and reaction vessels corresponding to the three-step decomposition reactions comprised in the S-I process. A fundamental research is experimentally performed on heat generation in a single bed packed with a hydrogen-absorbing alloy that may work at the H 2 production temperature. The hydrogen-absorbing alloy of Zr(V 1-x Fe x ) 2 is selected as a material that has a proper plateau pressure for the heat pump system operated between the input and output temperatures of HTGR and reaction vessels of the S-I cycle. Temperature jump due to heat generated when the alloy absorbs H 2 proves that the alloy-H 2 system can heat up the exhaust gas even at 600 deg. C without any external mechanical force. (authors)

An electrochemical method for determining hydrogen concentrations in metals and some applications

Science.gov (United States)

Danford, M. D.

1983-01-01

An electrochemical method was developed for the determination of hydrogen in metals using the EG&G-PARC Model 350A Corrosion Measurement Console. The method was applied to hydrogen uptake, both during electrolysis and electroplating, and to studies of hydrogen elimination and the effect of heat treatment on elimination times. Results from these studies are presented.

Electrochemical mass-flow control of hydrogen using a fullerene-based proton conductor

International Nuclear Information System (INIS)

Maruyama, Ryuichiro

2002-01-01

A membrane electrode assembly (MEA) was fabricated using proton conductive hydrogensulfated fullerenol (C 60 (OSO 3 H) n (OH) n ). Rate-controlled mass flow of hydrogen was performed by applying voltage to both electrodes of the MEA without humidification. The amount of the electrochemically transported hydrogen through the MEA increased as the applied current increased, obeying Faraday's law. Residual gas analysis of the transported hydrogen showed that the transported hydrogen contains trace amounts of water less than 1%

Renewable hydrogen production via thermochemical/electrochemical coupling

Energy Technology Data Exchange (ETDEWEB)

Ambrosini, Andrea [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Babiniec, Sean Michael [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Miller, James E. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-10-01

A coupled electrochemical/thermochemical cycle was investigated to produce hydrogen from renewable resources. Like a conventional thermochemical cycle, this cycle leverages chemical energy stored in a thermochemical working material that is reduced thermally by solar energy. However, in this concept, the stored chemical energy only needs to be partially, but not fully, capable of splitting steam to produce hydrogen. To complete the process, a proton-conducting membrane is driven to separate hydrogen as it is produced, thus shifting the thermodynamics toward further hydrogen production. This novel coupled-cycle concept provides several benefits. First, the required oxidation enthalpy of the reversible thermochemical material is reduced, enabling the process to occur at lower temperatures. Second, removing the requirement for spontaneous steam-splitting widens the scope of materials compositions, allowing for less expensive/more abundant elements to be used. Lastly, thermodynamics calculations suggest that this concept can potentially reach higher efficiencies than photovoltaic-to-electrolysis hydrogen production methods. This Exploratory Express LDRD involved assessing the practical feasibility of the proposed coupled cycle. A test stand was designed and constructed and proton-conducting membranes were synthesized. While the full proof of concept was not achieved, the individual components of the experiment were validated and new capabilities that can be leveraged by a variety of programs were developed.

Selective Electrochemical Generation of Hydrogen Peroxide from Water Oxidation

DEFF Research Database (Denmark)

Viswanathan, Venkatasubramanian; Hansen, Heine Anton; Nørskov, Jens K.

2015-01-01

evolution and form hydrogen peroxide. Using density functional theory calculations, we show that the free energy of adsorbed OH* can be used to determine selectivity trends between the 2e(-) water oxidation to H2O2 and the 4e(-) oxidation to O2. We show that materials which bind oxygen intermediates...... sufficiently weakly, such as SnO2, can activate hydrogen peroxide evolution. We present a rational design principle for the selectivity in electrochemical water oxidation and identify new material candidates that could perform H2O2 evolution selectively....

Electrochemical Hydrogen Evolution: Sabatier's Principle and the Volcano Plot

Science.gov (United States)

Laursen, Anders B.; Varela, Ana Sofia; Dionigi, Fabio; Fanchiu, Hank; Miller, Chandler; Trinhammer, Ole L.; Rossmeisl, Jan; Dahl, Soren

2012-01-01

The electrochemical hydrogen evolution reaction (HER) is growing in significance as society begins to rely more on renewable energy sources such as wind and solar power. Thus, research on designing new, inexpensive, and abundant HER catalysts is important. Here, we describe how a simple experiment combined with results from density functional…

New insights on electrochemical hydrogen storage in nanoporous carbons by in situ Raman spectroscopy

OpenAIRE

Leyva García, Sarai; Morallón Núñez, Emilia; Cazorla Amorós, Diego; Béguin, François; Lozano Castelló, Dolores

2014-01-01

In situ Raman spectroscopy was exploited to analyze the interaction between carbon and hydrogen during electrochemical hydrogen storage at cathodic conditions. Two different activated carbons were used and characterized by different electrochemical techniques in two electrolytes (6 M KOH and 0.5 M Na2SO4). The in situ Raman spectra collected showed that, in addition to the D and G bands associated to the graphitic carbons, two bands appear simultaneously at about 1110 and 1500 cm−1 under cath...

Cyclic voltammetry, square wave voltammetry, electrochemical impedance spectroscopy and colorimetric method for hydrogen peroxide detection based on chitosan/silver nanocomposite

Directory of Open Access Journals (Sweden)

Hoang V. Tran

2018-05-01

Full Text Available In this paper, we demonstrate a promising method to fabricate a non-enzymatic stable, highly sensitive and selective hydrogen peroxide sensor based on a chitosan/silver nanoparticles (CS/AgNPs hybrid. Using this composite, we elaborated both electrochemical and colorimetric sensors for hydrogen peroxide detection. The colorimetric sensor is based on a homogenous reaction which fades the color of CS/AgNPs solutions from red-orange to colorless depending on hydrogen peroxide concentration. For the electrochemical sensor, CS/AgNPs were immobilized on glassy carbon electrodes and hydrogen peroxide was measured using cyclic voltammetry, square wave voltammetry and electrochemical impedance spectroscopy. The response time is less than 10 s and the detection limit is 5 μM. Keywords: Spectrophotometric detection, Electrochemical impedance spectroscopy, Square wave voltammetry, Cyclic voltammetry, Chitosan/silver nanoparticles (CS/AgNPs hybrid, Hydrogen peroxide

Scanning electrochemical microscopy determination of hydrogen flux at liquid|liquid interface with potentiometric probe

OpenAIRE

Jedraszko, Justyna; Nogala, Wojciech; Adamiak, Wojciech; Girault, Hubert H.; Opallo, Marcin

2014-01-01

Scanning electrochemical microscopy potentiometric determination of local hydrogen concentration and its flux next to the liquid|liquid interface was demonstrated. This method is based on the shift of open circuit potential of Pt-based reversible hydrogen electrode. The detection system was verified with a system generating hydrogen under galvanostatic conditions. Then, it was applied to aqueous|1,2-dichloroethane interface where hydrogen is produced with decamethylferrocene as electron donor.

Studies on impurity control and hydrogen pumping with chromium gettering in ISX-B

International Nuclear Information System (INIS)

Mioduszewski, P.; Simpkins, J.E.; Edmonds, P.H.; Isler, R.C.; Lazarus, E.A.; Ma, C.H.; Murakami, M.; Wootton, A.J.

1984-01-01

Chromium gettering has been proven to be a trouble-free and efficient method of surface pumping in tokamaks. The impurity control capabilities are excellent and comparable to that of titanium. The hydrogen uptake is reduced to monolayer quantities on the surface. The expansion of the operating space is similar to that seen with titanium without the disadvantage of strongly increased hydrogen fluxes. Possible applications of chromium gettering are: impurity control in contemporary tokamaks; surface pumping in short pulse DT-burning devices to minimize tritium inventory, and wall conditioning of future large machines prior to operation

Electrochemical reduction of disulfide-containing proteins for hydrogen/deuterium exchange monitored by mass spectrometry

DEFF Research Database (Denmark)

Mysling, Simon; Salbo, Rune; Ploug, Michael

2014-01-01

Characterization of disulfide bond-containing proteins by hydrogen/deuterium exchange monitored by mass spectrometry (HDX-MS) requires reduction of the disulfide bonds under acidic and cold conditions, where the amide hydrogen exchange reaction is quenched (pH 2.5, 0 °C). The reduction typically...... of TCEP. In the present study, we explore the feasibility of using electrochemical reduction as a substitute for TCEP in HDX-MS analyses. Our results demonstrate that efficient disulfide bond reduction is readily achieved by implementing an electrochemical cell into the HDX-MS workflow. We also identify...... some challenges in using electrochemical reduction in HDX-MS analyses and provide possible conditions to attenuate these limitations. For example, high salt concentrations hamper disulfide bond reduction, necessitating additional dilution of the sample with aqueous acidic solution at quench conditions....

Fabrication of Nickel Nanotube Using Anodic Oxidation and Electrochemical Deposition Technologies and Its Hydrogen Storage Property

Directory of Open Access Journals (Sweden)

Yan Lv

2016-01-01

Full Text Available Electrochemical deposition technique was utilized to fabricate nickel nanotubes with the assistance of AAO templates. The topography and element component of the nickel nanotubes were characterized by TEM and EDS. Furthermore, the nickel nanotube was made into microelectrode and its electrochemical hydrogen storage property was studied using cyclic voltammetry. The results showed that the diameter of nickel nanotubes fabricated was around 20–100 mm, and the length of the nanotube could reach micron grade. The nickel nanotubes had hydrogen storage property, and the hydrogen storage performance was higher than that of nickel powder.

Hydrogen production by electrochemical decomposition of formic acid via solid polymer electrolyte

Energy Technology Data Exchange (ETDEWEB)

Kilic, Ebru Oender [KOSGEB Bursa Business Development Center, Besevler Kucuk Sanayi Sitesi 16149 Nilufer/Bursa (Turkey); Koparal, Ali Savas; Oeguetveren, Uelker Bakir [Anadolu University, Iki Eylul Campus, Applied Research Center for Environmental Problems 26555 Eskisehir (Turkey); Anadolu University, Iki Eylul Campus, Department of Environmental Engineering, 26555 Eskisehir (Turkey)

2009-01-15

The aim of this work is to investigate the feasibility of simultaneous hydrogen production by electrochemical decomposition of formic acid via solid polymer electrolyte (SPE) in an electrochemical reactor. Titanium oxide coated with iridium oxide as anode and carbon fibre with Pt catalyst as cathode were used in the experiments. Effects of applied current density, flow rates and temperature of formic acid solution, concentration of supporting electrolyte and pH of the solution on performance of the process have been investigated. The effect of membrane thickness has also been examined. The results suggest that electrolysis using SPE is a promising method for the treatment of organic pollutants. Hydrogen with purity of 99.999% at ambient temperature by using carbon fibre cathode with Pt catalyst can be produced simultaneously and COD removal efficiency of 95% has been achieved not requiring any chemical addition and temperature increase. Also complete electrochemical oxidation of formic acid at the original pH to CO{sub 2} and H{sub 2}O without production of intermediate has been proved by HPLC analysis. (author)

Combined heat and power (cogeneration) plant based on renewable energy sources and electrochemical hydrogen systems

Science.gov (United States)

Grigor'ev, S. A.; Grigor'ev, A. S.; Kuleshov, N. V.; Fateev, V. N.; Kuleshov, V. N.

2015-02-01

The layout of a combined heat and power (cogeneration) plant based on renewable energy sources (RESs) and hydrogen electrochemical systems for the accumulation of energy via the direct and inverse conversion of the electrical energy from RESs into the chemical energy of hydrogen with the storage of the latter is described. Some efficient technical solutions on the use of electrochemical hydrogen systems in power engineering for the storage of energy with a cyclic energy conversion efficiency of more than 40% are proposed. It is shown that the storage of energy in the form of hydrogen is environmentally safe and considerably surpasses traditional accumulator batteries by its capacitance characteristics, being especially topical in the prolonged absence of energy supply from RESs, e.g., under the conditions of polar night and breathless weather. To provide the required heat consumption of an object during the peak period, it is proposed to burn some hydrogen in a boiler house.

Electrochemical Determination of Hydrogen Entry to HSLA Steel during Pickling

Directory of Open Access Journals (Sweden)

Jari Aromaa

2018-01-01

Full Text Available Pickling with hydrochloric acid is a standard method to clean steel surfaces before hot-dip galvanizing. When normal low strength steels are pickled, hydrogen formed in pickling reactions does not have any significant harmful effect on the mechanical properties of steel. However, in pickling of steels with higher strength, the penetration of hydrogen into the steel may cause severe damages. The effect of pickling of high-strength low-alloy (HSLA steels was investigated using a cell construction based on the Devanathan-Stachurski method with modified anodic surface treatment and hydrogen production using acid. The penetration and the permeability of hydrogen were measured using an electrochemical cell with hydrochloric acid on the one side of the steel sample and a solution of NaOH on the other side. No protective coating, for example, palladium on the anodic side of the sample, is needed. The penetration rate of hydrogen into the steel and exit rate from the steel were lower for higher strength steel.

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

Electron cyclotron resonance hydrogen/helium plasma characterization and simulation of pumping in tokamaks

International Nuclear Information System (INIS)

Outten, C.A.

1992-01-01

Electron Cyclotron Resonance (ECR) plasmas have been employed to simulate the plasma conditions at the edge of a tokamak in order to investigate hydrogen/helium uptake in thin metal films. The process of microwave power absorption, important to characterizing the ECR plasma source, was investigated by measuring the electron density and temperature with a Langmuir probe and optical spectroscopy as a function of the magnetic field gradient and incident microwave power. A novel diagnostic, carbon resistance probe, provided a direct measure of the ion energy and fluence while measurements from a Langmuir probe were used for comparison. The Langmuir probe gave a plasma potential minus floating potential of 30 ± 5 eV, in good agreement with the carbon resistance probe result of ion energy ≤ 40 eV. The measured ion energy was consistent with the ion energy predicted from a model based upon divergent magnetic field extraction. Also, based upon physical sputtering of the carbon, the hydrogen fluence rate was determined to be 1 x 10 16 /cm 2 -sec for 50 Watts of incident microwave power. ECR hydrogen/helium plasmas were used to study preferential pumping of helium in candidate materials for tokamak pump-limiters: nickel, vanadium, aluminum, and nickel/aluminum multi-layers. Nickel and vanadium exhibited similar pumping capacities whereas aluminum showed a reduced capacity due to increased sputtering. A helium retention model based upon ion implantation ranges and sputtering rates agreed with the experimental data. A new multilayer/bilayer pumping concept showed improved pumping above that for single element films

Electrochemical synthesis of hydrogen peroxide: Rotating disk electrode and fuel cell studies

International Nuclear Information System (INIS)

Lobyntseva, Elena; Kallio, Tanja; Alexeyeva, Nadezda; Tammeveski, Kaido; Kontturi, Kyoesti

2007-01-01

The electrochemical reduction of oxygen on various catalysts was studied using the thin-layer rotating disk electrode (RDE) method. High-surface-area carbon was modified with an anthraquinone derivative and gold nanoparticles. Polytetrafluoroethylene (PTFE) and cationic polyelectrolyte (FAA) were used as binders in the preparation of thin-film electrodes. Our primary goal was to find a good electrocatalyst for the two-electron reduction of oxygen to hydrogen peroxide. All electrochemical measurements were carried out in 0.1 M KOH. Cyclic voltammetry was used in order to characterise the surface processes of the modified electrodes in O 2 -free electrolyte. The RDE results revealed that the carbon-supported gold nanoparticles are active catalysts for the four-electron reduction of oxygen in alkaline solution. Anthraquinone-modified high-area carbon catalyses the two-electron reduction at low overpotentials, which is advantageous for hydrogen peroxide production. In addition, the polymer electrolyte fuel cell technology was used for the generation of hydrogen peroxide. The cell was equipped with a bipolar membrane which consisted of commercial Nafion 117 as a cation-exchange layer and FT-FAA as an anion-exchange layer. The bipolar membranes were prepared by a hot pressing method. Use of the FAA ionomer as a binder for the anthraquinone-modified carbon catalyst resulted in production of hydrogen peroxide

Synthesis and electrochemical properties of binary MgTi and ternary MgTiX (X=Ni, Si) hydrogen storage alloys

NARCIS (Netherlands)

Gobichettipalayam Manivasagam, T.; Iliksu, M.; Danilov, D.L.; Notten, P.H.L.

2017-01-01

Mg-based hydrogen storage alloys are promising candidate for many hydrogen storage applications because of the high gravimetric hydrogen storage capacity and favourable (de)hydrogenation kinetics. In the present study we have investigated the synthesis and electrochemical hydrogen storage properties

Electrochemical permeation tests on the kinetics of the hydrogen absorption of palladium and iron

International Nuclear Information System (INIS)

Dafft, E.G.

1977-01-01

Electrochemical permeation tests were performed to investigate the kinetics of the hydrogen development and hydrogen absorption. The cathode side of the samples was galvanostatically cathodically polarized in different electrolyte solutions with and without additions. THe hydrogen atoms diffusing out of the opposite side for iron and α-palladium were oxidized with potentiostatic, sufficiently anodic polarization. The thus registered stationary current is proportional to the hydrogen activity on the cathode side. Test apparatus and conditions are described. The measurements on iron are discussed. (orig./HPOE) [de

Direct cryosorption pumping of an energetic hydrogen ion beam

International Nuclear Information System (INIS)

Schwenterly, S.W.; Ryan, P.M.; Tsai, C.C.

1979-01-01

Cryosorption pumps (CSP) are a prime candidate for the pumping of helium and deuterium-tritium (D-T) in tokamak divertor systems and may also see service in neutral beam injectors. However, the ability of a CSP to take high energy ions escaping from a plasma or neutral beam has not previously been demonstrated. In this study we arranged a 10-cm ion source of the type used in the Oak Ridge Tokamak (ORMAK) to inject a beam of ions directly into the inlet of a CSP. The pump contained two chevron baffles at 100K and 15K as well as a 15K cryosorption surface covered with a type 5A molecular sieve. The cryosurfaces were cooled by a closed-cycle helium refrigerator. For hydrogen ion pulses up to 11.5-keV energy and 1.3-A current, the pressure maintained during the pulse was only a few percent higher than that maintained with an equal flow of cold neutral gas. Pulse lengths of 100-300 ms were used. Calorimetric measurements showed that 40-60% of the I-V power was incident on the pump inlet. Cool-down and regeneration behavior of the pump will also be discussed

Low-temperature FTIR spectroscopy provides evidence for protein-bound water molecules in eubacterial light-driven ion pumps.

Science.gov (United States)

Nomura, Yurika; Ito, Shota; Teranishi, Miwako; Ono, Hikaru; Inoue, Keiichi; Kandori, Hideki

2018-01-31

Light-driven H + , Na + and Cl - pumps have been found in eubacteria, which convert light energy into a transmembrane electrochemical potential. A recent mutation study revealed asymmetric functional conversion between the two pumps, where successful functional conversions are achieved exclusively when mutagenesis reverses the evolutionary amino acid sequence changes. Although this fact suggests that the essential structural mechanism of an ancestral function is retained even after gaining a new function, questions regarding the essential structural mechanism remain unanswered. Light-induced difference FTIR spectroscopy was used to monitor the presence of strongly hydrogen-bonded water molecules for all eubacterial H + , Na + and Cl - pumps, including a functionally converted mutant. This fact suggests that the strongly hydrogen-bonded water molecules are maintained for these new functions during evolution, which could be the reason for successful functional conversion from Na + to H + , and from Cl - to H + pumps. This also explains the successful conversion of the Cl - to the H + pump only for eubacteria, but not for archaea. It is concluded that water-containing hydrogen-bonding networks constitute one of the essential structural mechanisms in eubacterial light-driven ion pumps.

An electrochemical sensor for monitoring oxygen or hydrogen in water

International Nuclear Information System (INIS)

Leitai Yang; Morris, D.R.; Lister, D.H.

1997-01-01

Preliminary studies have been done on a simple electrochemical sensor which shows promise as a cheap, robust instrument for measuring dissolved oxygen or hydrogen in water. The sensor is based upon the solid-state electrolyte ''Nafion'' (trade name of perfluorinated sulphonic acid, manufactured by DuPont Inc.). The Nafion was dissolved in a mixture of aliphatic alcohols, made into a slurry with platinum black, and applied to a ∼1 cm-square electrode made of stainless steel gauze. The potential of the electrode was measured relative to a standard calomel electrode (SCE) in acid solutions at room temperature through which mixtures of oxygen and nitrogen or hydrogen and nitrogen were bubbled. The sensor was responsive to the equilibrating gas with good reproducibility. A similar sensor without the Nafion was not at all sensitive to changes in oxygen concentration. The voltage response of the sensor showed non-Nernstian behaviour, which suggests that the electrochemical reactions at the electrode surface are complex. Further testing of the sensor is required to verify its sensitivity and responsiveness in typical reactor coolant chemistries and to demonstrate its durability over a range of temperatures. (author). 4 refs, 4 figs, 1 tab

An electrochemical sensor for monitoring oxygen or hydrogen in water

Energy Technology Data Exchange (ETDEWEB)

Yang, Leitai; Morris, D R; Lister, D H [University of New Brunswick, Fredericton (Canada). Dept. of Chemical Engineering

1997-02-01

Preliminary studies have been done on a simple electrochemical sensor which shows promise as a cheap, robust instrument for measuring dissolved oxygen or hydrogen in water. The sensor is based upon the solid-state electrolyte ``Nafion`` (trade name of perfluorinated sulphonic acid, manufactured by DuPont Inc.). The Nafion was dissolved in a mixture of aliphatic alcohols, made into a slurry with platinum black, and applied to a {approx}1 cm-square electrode made of stainless steel gauze. The potential of the electrode was measured relative to a standard calomel electrode (SCE) in acid solutions at room temperature through which mixtures of oxygen and nitrogen or hydrogen and nitrogen were bubbled. The sensor was responsive to the equilibrating gas with good reproducibility. A similar sensor without the Nafion was not at all sensitive to changes in oxygen concentration. The voltage response of the sensor showed non-Nernstian behaviour, which suggests that the electrochemical reactions at the electrode surface are complex. Further testing of the sensor is required to verify its sensitivity and responsiveness in typical reactor coolant chemistries and to demonstrate its durability over a range of temperatures. (author). 4 refs, 4 figs, 1 tab.

The impact of surface composition on Tafel kinetics leading to enhanced electrochemical insertion of hydrogen in palladium

Science.gov (United States)

Dmitriyeva, Olga; Hamm, Steven C.; Knies, David L.; Cantwell, Richard; McConnell, Matt

2018-05-01

Our previous work experimentally demonstrated the enhancement of electrochemical hydrogen insertion into palladium by modifying the chemical composition of the cathode surface with Pb, Pt and Bi, referred to as surface promoters. The experiment demonstrated that an optimal combination of the surface promoters led to an increase in hydrogen fugacity of more than three orders of magnitude, while maintaining the same current density. This manuscript discusses the application of Density Functional Theory (DFT) to elucidate the thermodynamics and kinetics of observed enhancement of electrochemical hydrogen insertion into palladium. We present theoretical simulations that: (1) establish the elevation of hydrogen's chemical potential on Pb and Bi surfaces to enhance hydrogen insertion, (2) confirm the increase of a Tafel activation barrier that results in a decrease of the reaction rate at the given hydrogen overpotential, and (3) explain why the surface promoter's coverage needs to be non-uniform, namely to allow hydrogen insertion into palladium bulk while simultaneously locking hydrogen below the surface (the corking effect). The discussed DFT-based method can be used for efficient scanning of different material configurations to design a highly effective hydrogen storage system.

Hydrogen fuel : well-to-pump pathways for 2050

Energy Technology Data Exchange (ETDEWEB)

Molburg, J. [Argonne National Lab., IL (United States); Mintz, M.; Folga, S.; Gillette, J.

2002-07-01

The authors discussed the topic of hydrogen fuels, and began the presentation by stating that the carbon intensity of world primary energy has been falling and hydrogen intensity has been rising. The declines in carbon can be explained by efficiency gains and fuel switches. There are several alternatives to gasoline fuel for vehicles, such as hydrogen, compressed natural gas, compressed natural gas/hydrogen. Emissions of greenhouse gases in the atmosphere represent a growing concern. The authors discussed four hydrogen pathways that have been modeled. They indicated that both natural gas pathways required additional natural gas transmission and storage. To better illustrate the hydrogen pathway, a conceptual representation of hydrogen pipeline loop supporting local hydrogen delivery was displayed. Some hydrogen distribution assumptions for centralized hydrogen production were examined. A cost modeling procedure was described, with the following topics: defining paths, determining tank-in fuel requirement, size pathway components, estimating component costs, and calculating pathway costs. The results indicated that the natural gas-based pathways were sensitive to feedstock cost, while coal and nuclear were not. Some of the conclusions that were arrived at were: (1) on a well-to-pump basis, with current technologies, the unit cost of hydrogen is expected to be 2 to 3 time that of gasoline, (2) the mpge of hydrogen-fueled vehicles must be more than double gasoline, and (3) hydrogen transport and production are the largest components of all pathways. For the future, the focus has to be on transition, including total and unit costs through study time frame, penetration of hydrogen blends, and niche markets. One must compare apples to apples, i e cost of infrastructure components over time, and learning curves. Pathways and scenarios must be re-examined, to include issues such as truck, rail marine market penetration; and hydrogen carrier pathways. Disruptive

A mathematical model for hydrogen evolution in an electrochemical cell and experimental validation

International Nuclear Information System (INIS)

Mahmut D Mat; Yuksel Kaplan; Beycan Ibrahimoglu; Nejat Veziroglu; Rafig Alibeyli; Sadiq Kuliyev

2006-01-01

Electrochemical reaction is largely employed in various industrial areas such as hydrogen production, chlorate process, electroplating, metal purification etc. Most of these processes often take place with gas evaluation on the electrodes. Presence of gas phase in the liquid phase makes the problem two-phase flow which is much knowledge available from heat transfer and fluid mechanics studies. The motivation of this study is to investigate hydrogen release in an electrolysis processes from two-phase flow point of view and investigate effect of gas release on the electrolysis process. Hydrogen evolution, flow field and current density distribution in an electrochemical cell are investigated with a two-phase flow model. The mathematical model involves solutions of transport equations for the variables of each phase with allowance for inter phase transfer of mass and momentum. An experimental set-up is established to collect data to validate and improve the mathematical model. Void fraction is determined from measurement of resistivity changes in the system due to the presence of bubbles. A good agreement is obtained between numerical results and experimental data. (authors)

A nanostructured Ni/graphene hybrid for enhanced electrochemical hydrogen storage

International Nuclear Information System (INIS)

Choi, Moon-Hyung; Min, Young-Je; Gwak, Gyeong-Hyeon; Paek, Seung-Min; Oh, Jae-Min

2014-01-01

Highlights: • Graphene oxide(GO) was hybridized with the Ni(OH) 2 . • The Ni(OH) 2 /GO was reduced to Ni/graphene. • XRD, TEM, and X-ray absorption spectroscopy were examined. • The hydrogen storage property of Ni/graphene was significantly enhanced. - Abstract: To fabricate electrochemical hydrogen storage materials with delaminated structure, the graphene oxide (GO) in the ethylene glycol solution was reassembled in the presence of the precursor of Ni nanoparticles, and then, the reassembled hybrid was reduced under hydrogen atmosphere to obtain Ni/graphene hybrid. X-ray diffraction patterns and X-ray absorption spectscopic (XAS) analysis clearly show that Ni nanoparticles in Ni/graphene hybrid maintain its nanosized nature even after hybridization with graphene nanosheet (GNS). According to the TEM analysis, the Ni nanoparticles with an average size of 5.2 nm are homogeneously distributed onto the GNS in such a way that the nanoporous structure with much amount of void spaces could be fabricated. The obtained Ni/GNS exhibits a hydrogen storage capacity of 160 mA h/g, while the specific capacity of the graphene nanosheet was only 21 mA h/g. A flexible delaminated structure of Ni/GNS nanocomposite could provide additional intercalation sites for accommodation of hydrogen, leading to the enhancement of hydrogen storage capacity

Enhanced Electrochemical Hydrogen Storage Performance on the Porous Graphene Network Immobilizing Cobalt Metal Nanoparticle

Energy Technology Data Exchange (ETDEWEB)

Kang, Myunggoo; Lee, Dong Heon; Jung, Hyun [Dongguk University, Seoul (Korea, Republic of)

2016-05-15

In this study, we attempted to apply Co metal nanoparticles decorated on the surface of the porous graphene (Co-PG) as the electrochemical hydrogen storage system. Co-PG was successfully synthesized by the soft-template method. To determine the synthetic strategy of porous graphene and Co nanoparticles, we compare the obtained Co-PG with two different materials such as Co nanoparticle decorated reduced graphene oxide without soft-template (Co-RGO) and porous graphene without Co nanoparticle (PG). The experimental details regarding the synthesis and characterization of the Co-PG, Co-RGO, and PG samples are provided in Supporting Information. Co-PG with interpenetrating porous networks and immobilized Co metal nanoparticles were successfully synthesized by the soft-template method. The obtained Co-PG exhibited high-surface area with ink-bottle open pores owing to the homogeneous dispersion of P123 micellar rods. The XRD and FE-SEM analyses clearly confirm that Co nanoparticles were immobilized on to the surface of porous graphene without any significant aggregation. The as-obtained Co-PG showed good electrochemical performance such as capacity and cycle stability for hydrogen storage. Based on these results, we believe that the Co-PG with a high-specific surface area could be worthwhile to investigate as not only electrochemical hydrogen storage materials but also other energy storage applications.

Enhanced Electrochemical Hydrogen Storage Performance on the Porous Graphene Network Immobilizing Cobalt Metal Nanoparticle

International Nuclear Information System (INIS)

Kang, Myunggoo; Lee, Dong Heon; Jung, Hyun

2016-01-01

In this study, we attempted to apply Co metal nanoparticles decorated on the surface of the porous graphene (Co-PG) as the electrochemical hydrogen storage system. Co-PG was successfully synthesized by the soft-template method. To determine the synthetic strategy of porous graphene and Co nanoparticles, we compare the obtained Co-PG with two different materials such as Co nanoparticle decorated reduced graphene oxide without soft-template (Co-RGO) and porous graphene without Co nanoparticle (PG). The experimental details regarding the synthesis and characterization of the Co-PG, Co-RGO, and PG samples are provided in Supporting Information. Co-PG with interpenetrating porous networks and immobilized Co metal nanoparticles were successfully synthesized by the soft-template method. The obtained Co-PG exhibited high-surface area with ink-bottle open pores owing to the homogeneous dispersion of P123 micellar rods. The XRD and FE-SEM analyses clearly confirm that Co nanoparticles were immobilized on to the surface of porous graphene without any significant aggregation. The as-obtained Co-PG showed good electrochemical performance such as capacity and cycle stability for hydrogen storage. Based on these results, we believe that the Co-PG with a high-specific surface area could be worthwhile to investigate as not only electrochemical hydrogen storage materials but also other energy storage applications

Formation of Hydrogen Peroxide by Electrochemical Reduction of Molecular Oxygen using Luminol Chemiluminescence

International Nuclear Information System (INIS)

Rana, Sohail

2005-01-01

Formation of hydrogen peroxide by electrochemical reduction of molecular oxygen was examined by measuring luminol chemiluminescence and absorption spectrum using flow-injection method. Ferryl porphyrin is widely accepted as responsible species to stimulate the emission in hydrogen peroxide/ iron porphyrin/ luminol system. Emission was observed under cathodic potentials (0.05V at pH2.0 and -0.3V at pH11.0) by the electrochemical reduction of aerated electrolytes solution but emission was observed at anodic potentials. Iron porphyrin solution was added at down stream of the working electrode and was essential for the emission. Removal of the dissolved molecular oxygen resulted in the decrease of emission intensity by more than 70%. In order to examine the life time of reduced active species, delay tubes were introduced between working electrode Fe TMPyP inlet. Experimental results suggested the active species were stable for quite a long period. The emission was quenched considerably (>90%) when hydroperoxy was added at the down stream of working electrode whereas the Superoxide dismutase (SOD) had little effect and mannitol had no effect. The spectra at reduction potential under aerated condition were shifted to the longer wavelength (>430nm) compared to the original spectrum of Fe TMPyP (422nm), indicating that the ferryl species were mixed to some extent. These observations lead to the conclusion that hydrogen peroxide was produced first by electrochemical reduction of molecular oxygen which then converted Fe TMPyP into O=FeTMPyP to activate luminol. Comparing emission intensities with the reference experiments, the current efficiencies for the formation of hydrogen peroxide were estimated as about 30-65% in all over the pH range used. (author)

[The effect of hydrogen peroxide on the electrochemical corrosion properties and metal ions release of nickel-chromium dental alloys].

Science.gov (United States)

Wang, Jue; Qiao, Guang-yan

2013-04-01

To investigate the effect of hydrogen peroxide on the electrochemical corrosion and metal ions release of nickel-chromium dental alloys. The corrosion resistance of nickel-chromium dental alloys was compared by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curve (PD) methods in artificial saliva after immersed in different concentrations of hydrogen peroxide for 112 h. The metal ions released from nickel-chromium dental alloys to the artificial saliva were detected after electrochemical measurements using inductively coupled plasma mass spectrometry (ICP-MS). The data was statistically analyzed by analysis of variance (ANOVA) using SPSS 13.0 software package. The electrochemical experiment showed that the sequence of polarization resistance in equivalent circuit (Rct), corrosion potential (Ecorr), pitting breakdown potential (Eb), and the difference between Ecorr and Eb representing the "pseudo-passivation" (δE) of nickel-chromium alloys in artificial saliva was 30% alloys to the artificial saliva, and the order of the concentrations of metal ions was 0% corrosion resistance of nickel-chromium dental alloys decrease after immersed in different concentrations of hydrogen peroxide for 112 h. Nickel-chromium dental alloys are more prone to corrosion in the artificial saliva with the concentration of hydrogen peroxide increased, and more metal ions are released in the artificial saliva.

Electrochemical measurement of tritium and hydrogen permeation through iron membranes

International Nuclear Information System (INIS)

Hagi, Hideki; Hayashi, Yasunori

1988-01-01

Permeation rates of tritium and hydrogen through iron were measured by the electrochemical method in which an aqueous solution containing 3.7 x 10 12 Bq/m 3 tritium was used as a cathodic electrolyte. Tritium and hydrogen were introduced from one side of a specimen by cathodic polarization with a constant current density, while at the other side of the specimen the permeated tritium and hydrogen were extracted by potentiostatical ionization. Nearly all of the potentiostatic current of the extraction side stands for the ionization of hydrogen, because the concentration of tritium in the cathodic electrolyte is very small. The amount of permeated hydrogen was obtained by integrating the anodic current, and that of tritium was determined by measuring the radioactivity of the electrolyte sampled from the extraction side. The separation factor for permeation obtained under steady state conditions (the ratio of permeation rates of hydrogen to tritium divided by the ratio of the concentration of hydrogen to tritium in the charging electrolyte) is 12 at 288 K. This value is independent of cathodic current density. Diffusion coefficients of tritium (D T ) and hydrogen (D H ) in iron were determined from the time lag of tritium and hydrogen permeation. For annealed specimens at 286 K, D T = 9 x 10 -10 m 2 /s and D H = 4 x 10 -9 m 2 /s, and for 9% cold-worked specimens at 284 K, D T = 3 x 10 -10 m 2 /s and D H = 4 x 10 -10 m 2 /s. (author)

Electrochemical measurement of tritium and hydrogen permeation through iron membranes

International Nuclear Information System (INIS)

Hagi, Hideki; Hayashi, Yasunori

1987-01-01

Permeation rates of tritium and hydrogen through iron were measured by the electro-chemical method in which an aqueous solution containing 3.7 x 10 12 Bq/m 3 tritium was used as a cathodic electrolyte. Tritium and hydrogen were introduced from one side of a specimen by cathodic polarization with a constant current density, while at the other side of the specimen the permeated tritium and hydrogen were extracted by potentiostatical ionization. Nearly all of the potentiostatic current on the extraction side is produced by the ionization of hydrogen, because the concentration of tritium in the cathodic electrolyte is very small. The amount of permeated hydrogen was obtained by integrating the potentiostatic current, and that of permeated tritium was determined by measuring the radioactivity of the electrolyte sampled from the anodic side. The separation factor for permeation obtained under steady state conditions (the ratio of permeation rates of hydrogen to tritium divided by the ratio of the concentration of hydrogen to tritium in the cathodic electrolyte) is 12 at 288 K. This value is independent of cathodic current density. Diffusion coefficients of tritium (D T ) and hydrogen (D H ) in iron were determined from the tritium and hydrogen permeation by using time lag technique. For annealed iron at 286 K, D T = 9 x 10 -10 m 2 /s and D H = 4 x 10 -9 m 2 /s, and for 9 % cold-worked iron at 284 K, D T = 3 x 10 -10 m 2 /s and D H = 4 x 10 -10 m 2 /s. (author)

Electrochemical promotion of NO reduction by hydrogen on a platinum/polybenzimidazole catalyst

DEFF Research Database (Denmark)

Petrushina, Irina; Bandur, Viktor; Cappeln, Frederik Vilhelm

2003-01-01

The electrochemical promotion of catalytic NO reduction by hydrogen was studied using a (NO, H-2, Ar), Pt polybenzimidazole (PBI)-H3PO4\\Pt, (H-2, Ar) fuel cell at 135degreesC. A mixture of NO/H-2/Ar was used as the working mixture at one electrode and a mixture of H-2/Ar was used as reference and...... at the negative polarization can be attributed to the electrochemical production of the promoters. At low gas flow rates, a charge-induced change of the strength of chemisorptive bonds can take place.......The electrochemical promotion of catalytic NO reduction by hydrogen was studied using a (NO, H-2, Ar), Pt polybenzimidazole (PBI)-H3PO4\\Pt, (H-2, Ar) fuel cell at 135degreesC. A mixture of NO/H-2/Ar was used as the working mixture at one electrode and a mixture of H-2/Ar was used as reference...... and counter gas at the other electrode. Products of NO reduction (N-2 and H2O) were analyzed by an on-line mass spectrometer. At high NO+H-2+Ar flow rate (17 mL/min; 17 and 354 mL/min, respectively, at atmospheric pressure) the maximum rate enhancement ratio was 4.65. At low NO+H-2+Ar flow rate (17 mL/min; 17...

Electrochemical methods to study hydrogen production during interaction of copper with deoxygenated aqueous solution

International Nuclear Information System (INIS)

Lilja, Christina; Betova, Iva; Bojinov, Martin

2016-01-01

In some countries, spent nuclear fuel is planned to be encapsulated in canisters with a copper shell for corrosion protection, for further disposal in geologic repositories. The possibilities for corrosion after oxygen depletion must be evaluated, even if copper is considered to be immune in oxygen-free water. To follow the interaction of copper with deoxygenated aqueous solution, open-circuit potentiometric and electrochemical impedance measurements have been coupled to in-situ detection of cupric ion, dissolved molecular hydrogen and oxygen concentrations using electrochemical sensors. A kinetic model that considers the production of hydrogen as a catalytic process, the rate of which is proportional to the surface coverage of an intermediate species formed during interaction between copper and the solution is used to interpret the results. Kinetic parameters are estimated by a simultaneous fit of the experimental impedance spectra, the open circuit potential and cupric ion concentration as depending on temperature (22–70 °C) and exposure time (up to 720 h) to the model equations. Using the obtained values and a balance equation of hydrogen production on copper and its diffusion out of the cell through its walls, the kinetic parameters of this process are estimated by fitting dissolved molecular hydrogen concentration vs. time data at the three temperatures.

Electrochemical deposition of Prussian blue on hydrogen terminated silicon(111)

International Nuclear Information System (INIS)

Zhao Jianwei; Zhang Yan; Shi Chuanguo; Chen, Hongyuan; Tong Lianming; Zhu Tao; Liu Zhongfan

2006-01-01

Electrochemical deposition of Prussian blue (PB) was performed by cyclic voltammetry on hydrogen terminated n-type Si(111) surface. The characterization of the samples based on atomic force microscopy and X-ray diffraction spectroscopy showed a nanocrystal form of the PB films on the silicon surface. The thickness of PB films as a function of the potential cycling number was monitored simultaneously by Raman spectroscopy, proving that the growth of the films is in a good controllable manner

A high-porosity carbon molybdenum sulphide composite with enhanced electrochemical hydrogen evolution and stability

DEFF Research Database (Denmark)

Laursen, Anders B.; Vesborg, Peter C. K.; Chorkendorff, Ib

2013-01-01

This work describes a highly active and stable acid activated carbon fibre and amorphous MoSx composite hydrogen evolution catalyst. The increased electrochemical-surface area is demonstrated to cause increased catalyst electrodeposition and activity. These composite electrodes also show...

Mechanical ball-milling preparation of fullerene/cobalt core/shell nanocomposites with high electrochemical hydrogen storage ability.

Science.gov (United States)

Bao, Di; Gao, Peng; Shen, Xiande; Chang, Cheng; Wang, Longqiang; Wang, Ying; Chen, Yujin; Zhou, Xiaoming; Sun, Shuchao; Li, Guobao; Yang, Piaoping

2014-02-26

The design and synthesis of new hydrogen storage nanomaterials with high capacity at low cost is extremely desirable but remains challenging for today's development of hydrogen economy. Because of the special honeycomb structures and excellent physical and chemical characters, fullerenes have been extensively considered as ideal materials for hydrogen storage materials. To take the most advantage of its distinctive symmetrical carbon cage structure, we have uniformly coated C60's surface with metal cobalt in nanoscale to form a core/shell structure through a simple ball-milling process in this work. The X-ray diffraction (XRD), scanning electron microscope (SEM), Raman spectra, high-solution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectrometry (EDX) elemental mappings, and X-ray photoelectron spectroscopy (XPS) measurements have been conducted to evaluate the size and the composition of the composites. In addition, the blue shift of C60 pentagonal pinch mode demonstrates the formation of Co-C chemical bond, and which enhances the stability of the as-obtained nanocomposites. And their electrochemical experimental results demonstrate that the as-obtained C60/Co composites have excellent electrochemical hydrogen storage cycle reversibility and considerably high hydrogen storage capacities of 907 mAh/g (3.32 wt % hydrogen) under room temperature and ambient pressure, which is very close to the theoretical hydrogen storage capacities of individual metal Co (3.33 wt % hydrogen). Furthermore, their hydrogen storage processes and the mechanism have also been investigated, in which the quasi-reversible C60/Co↔C60/Co-Hx reaction is the dominant cycle process.

Electrochemical preparation and characteristics of Ni-Co-LaNi5 composite coatings as electrode materials for hydrogen evolution

International Nuclear Information System (INIS)

Wu Gang; Li Ning; Dai Changsong; Zhou Derui

2004-01-01

Electrocatalytic activity for the hydrogen evolution reaction on Ni-Co-LaNi 5 composite electrodes prepared by electrochemical codeposition technique was evaluated. The relationship between the current density for hydrogen evolution reaction and the amount of LaNi 5 particles in Ni-Co baths is like the well-known 'volcano plot'. The Surface morphology and microstructure of Ni-Co-LaNi 5 coatings were determined by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). The kinetic parameters were determined from electrochemical steady-state Tafel polarization and electrochemical impedance spectroscopy technology in 1 M NaOH solution. The values obtained for the apparent energies of activation are 32.48, 46.29 and 57.03 kJ mol -1 for the Ni-Co-LaNi 5 , Ni-Co and Ni electrodes, respectively. The hydrogen evolution reaction on Ni-Co-LaNi 5 proceeds via Volmer-Tafel reaction route with the mixed rate determining characteristics. The composite coating Ni-Co-LaNi 5 is catalytically more active than Ni and Ni-Co electrodes due to the increase in its real surface areas and the decrease in the apparent free energy of activation caused by the electrocatalytic synergistic effect of the Ni-Co alloys and the hydrogen storage intermetallic particles on the electrode surface

Adsorption pump for helium pumping out

International Nuclear Information System (INIS)

Donde, A.L.; Semenenko, Yu.E.

1981-01-01

Adsorption pump with adsorbent cooling by liquid helium is described. Shuttered shield protecting adsorbent against radiation is cooled with evaporating helium passing along the coil positioned on the shield. The pump is also equipped with primed cylindrical shield, cooled with liquid nitrogen. The nitrogen shield has in the lower part the shuttered shield, on the pump casing there is a valve used for pump pre-burning, and valves for connection to recipient as well. Pumping- out rates are presented at different pressures and temperatures of adsorbent. The pumping-out rate according to air at absorbent cooling with liquid nitrogen constituted 5x10 -4 Pa-3000 l/s, at 2x10 -2 Pa-630 l/s. During the absorbent cooling with liquid hydrogen the pumping-out rate according to air was at 4x10 -4 Pa-580 l/s, at 2x10 -3 Pa-680 l/s, according to hydrogen - at 8x10 -5 Pa-2500 l/s, at 5x10 -3 Pa-4200 l/s. During adsorbent cooling with liquid helium the rate of pumping-out according to hydrogen at 3x10 5 Pa-2400% l/s, at 6x10 3 Pa-1200 l/s, and according to helium at 3.5x10 -5 Pa-2800 l/s, at 4x10 -3 Pa-1150 l/s. The limit vacuum is equal to 1x10 -7 Pa. The volume of the vessel with liquid helium is equal to 3.5 l. Helium consumption is 80 cm 3 /h. Consumption of liquid nitrogen from the shield is 400 cm 3 /h. The limit pressure in the pump is obtained after forevacuum pumping-out (adsorbent regeneration) at 300 K temperature. The pump is made of copper. The pump height together with primed tubes is 800 mm diameter-380 mm [ru

Test report for the run-in acceptance testing of the hydrogen mitigation retrieval Pump-3

International Nuclear Information System (INIS)

Berglin, B.G.; Nash, Ch.R.

1997-01-01

This report will provide the findings of the demonstration test conducted on the Double-Shell Tank (DST) 241-SY-101 HMR Pump-3 in accordance with WHC-SDWM-TP-434 ''Test plan for run-in acceptance testing of hydrogen mitigation/retrieval pump-3'' at the 400 Area Maintenance and Storage Facility (MASF) building from 7 June 1996 through 30 July 1996 per work package 4A-96-92/W. The DST 241-SY-101 hydrogen mitigation retrieval Pump-3 is a 200-HP submersible electric driven pump that has been modified for use in the DST 241-SY-101 containing mixed waste located in the 200W area. The pump has a motor driven rotation mechanism that allows the pump column to rotate through 355 degree. Prior to operation, pre-operational checks were performed which included loop calibration grooming and alignment of instruments, learning how plumb HMR-3 assembly hung in a vertical position and bump test of the motor to determine rotation direction. The pump was tested in the MASF Large Diameter Cleaning Vessel (LDCV) with process water at controlled temperatures and levels. In addition, the water temperature of the cooling water to the motor oil heat exchanger was recorded during testing. A 480-volt source powered a Variable Frequency Drive (VFD). The VFD powered the pump at various frequencies and voltages to control speed and power output of the pump. A second VFD powered the oil cooling pump. A third VFD was not available to operate the rotational drive motor during the 72 hour test, so it was demonstrated as operational before and after the test. A Mini Acquisition and Control System (Mini-DACS) controls pump functions and monitoring of the pump parameters. The Mini-DACS consists of three computers, software and some Programmable Logic Controllers (PLC). Startup and shutdown of either the pump motor or the oil cooling pump can be accomplished by the Mini-DACS. When the pump was in operation, the Mini-DACS monitors automatically collects data electronically. However, some required data

A Study of the Mechanism of the Hydrogen Evolution Reaction on Nickel by Surface Interrogation Scanning Electrochemical Microscopy.

Science.gov (United States)

Liang, Zhenxing; Ahn, Hyun S; Bard, Allen J

2017-04-05

The hydrogen evolution reaction (HER) on Ni in alkaline media was investigated by scanning electrochemical microscopy under two operating modes. First, the substrate generation/tip collection mode was employed to extract the "true" cathodic current associated with the HER from the total current in the polarization curve. Compared to metallic Ni, the electrocatalytic activity of the HER is improved in the presence of the low-valence-state oxide of Ni. This result is in agreement with a previous claim that the dissociative adsorption of water can be enhanced at the Ni/Ni oxide interface. Second, the surface-interrogation scanning electrochemical microscopy (SI-SECM) mode was used to directly measure the coverage of the adsorbed hydrogen on Ni at given potentials. Simulation indicates that the hydrogen coverage follows a Frumkin isotherm with respect to the applied potential. On the basis of the combined analysis of the Tafel slope and surface hydrogen coverage, the rate-determining step is suggested to be the adsorption of hydrogen (Volmer step) in the investigated potential window.

On the Potential of Hydrogen-Powered Hydraulic Pumps for Soft Robotics.

Science.gov (United States)

Desbiens, Alexandre B; Bigué, Jean-Philippe Lucking; Véronneau, Catherine; Masson, Patrice; Iagnemma, Karl; Plante, Jean-Sébastien

2017-12-01

To perform untethered operations, soft robots require mesoscale power units (10-1000 W) with high energy densities. In this perspective, air-breathing combustion offers an interesting alternative to battery-powered systems, provided sufficient overall energy conversion efficiency can be reached. Implementing efficient air-breathing combustion in mesoscale soft robots is notoriously difficult, however, as it requires optimization of very small combustion actuators and simultaneous minimization of fluidic (e.g., hydraulic) losses, which are both inversely impacted by actuations speeds. To overcome such challenges, this article proposes and evaluates the potential of hydrogen-powered, hydraulic free-piston pump architecture. Experimental data, taken from two combustion-driven prototypes, reveal (1) the fundamental role of using hydrogen as the source of fuel to reduce heat losses, (2) the significant impact of compression ratio, equivalence ratio, and surface-to-volume ratio on energy conversion efficiency, and (3) the importance of load matching between combustion and fluidic transmission. In this work, a small-bore combustion actuator demonstrated a 20% efficiency and a net mean output power of 26 W, while a big-bore combustion actuator reached a substantially higher efficiency of 35% and a net mean output power of 197 W. Using the small-bore combustion actuator, the hydrogen-powered, hydraulic free-piston pump provided a 4.6% overall efficiency for a 2.34 W net mean output power, thus underlying the potential of the approach for mesoscale soft robotic applications.

Thermo-electrochemical production of compressed hydrogen from methane with near-zero energy loss

Science.gov (United States)

Malerød-Fjeld, Harald; Clark, Daniel; Yuste-Tirados, Irene; Zanón, Raquel; Catalán-Martinez, David; Beeaff, Dustin; Morejudo, Selene H.; Vestre, Per K.; Norby, Truls; Haugsrud, Reidar; Serra, José M.; Kjølseth, Christian

2017-11-01

Conventional production of hydrogen requires large industrial plants to minimize energy losses and capital costs associated with steam reforming, water-gas shift, product separation and compression. Here we present a protonic membrane reformer (PMR) that produces high-purity hydrogen from steam methane reforming in a single-stage process with near-zero energy loss. We use a BaZrO3-based proton-conducting electrolyte deposited as a dense film on a porous Ni composite electrode with dual function as a reforming catalyst. At 800 °C, we achieve full methane conversion by removing 99% of the formed hydrogen, which is simultaneously compressed electrochemically up to 50 bar. A thermally balanced operation regime is achieved by coupling several thermo-chemical processes. Modelling of a small-scale (10 kg H2 day-1) hydrogen plant reveals an overall energy efficiency of >87%. The results suggest that future declining electricity prices could make PMRs a competitive alternative for industrial-scale hydrogen plants integrating CO2 capture.

Electrochemical Synthesis of Polypyrrole, Reduced Graphene Oxide, and Gold Nanoparticles Composite and Its Application to Hydrogen Peroxide Biosensor

Directory of Open Access Journals (Sweden)

Baoyan Wu

2016-11-01

Full Text Available Here we report a facile eco-friendly one-step electrochemical approach for the fabrication of a polypyrrole (PPy, reduced graphene oxide (RGO, and gold nanoparticles (nanoAu biocomposite on a glassy carbon electrode (GCE. The electrochemical behaviors of PPy–RGO–nanoAu and its application to electrochemical detection of hydrogen peroxide were investigated by cyclic voltammetry. Graphene oxide and pyrrole monomer were first mixed and casted on the surface of a cleaned GCE. After an electrochemical processing consisting of the electrooxidation of pyrrole monomer and simultaneous electroreduction of graphene oxide and auric ions (Au3+ in aqueous solution, a PPy–RGO–nanoAu biocomposite was synthesized on GCE. Each component of PPy–RGO–nanoAu is electroactive without non-electroactive substance. The obtained PPy–RGO–nanoAu/GCE exhibited high electrocatalytic activity toward hydrogen peroxide, which allows the detection of hydrogen peroxide at a negative potential of about −0.62 V vs. SCE. The amperometric responses of the biosensor displayed a sensitivity of 40 µA/mM, a linear range of 32 µM–2 mM, and a detection limit of 2.7 µM (signal-to-noise ratio = 3 with good stability and acceptable reproducibility and selectivity. The results clearly demonstrate the potential of the as-prepared PPy–RGO–nanoAu biocomposite for use as a highly electroactive matrix for an amperometric biosensor.

Effects of microstructures on hydrogen induced cracking of electrochemically hydrogenated double notched tensile sample of 4340 steel

Energy Technology Data Exchange (ETDEWEB)

Sk, Mobbassar Hassan, E-mail: Skmobba@qu.edu.qa [Center for Advanced Materials, Qatar University, Doha (Qatar); Overfelt, Ruel A. [Materials Research and Education Center, Materials Engineer, Auburn University, Auburn, AL (United States); Abdullah, Aboubakr M. [Center for Advanced Materials, Qatar University, Doha (Qatar)

2016-04-06

Quantitative fractographic characteristics of 4340 steel is demonstrated for a grain size range of 10−100 µm and hardness range of 41–52 HRC. Double-notched tensile samples were electrochemically charged in-situ with hydrogen in 0.5 m H{sub 2}SO{sub 4}+5 mg/l As{sub 2}O{sub 3} solution for 0–40 min charging time. Hydrogen induced fracture initiations were analyzed by novel metallographic investigation of the “unbroken” notch while the overall fractographic behaviors were examined by the scanning electron microscopic imaging of the fracture surfaces of the actually broken notch. Effect of hydrogen was predominantly manifested as intergranular fracture for the harder samples and quasi-cleavage fracture for the softer counterparts. 10–40 µm samples showed the maximum intensity of the hydrogen induced fracture features (intergranular and/or quasi-cleavage) close to the notch which gradually reduced with increasing distance from the notch. The largest grained samples (100 µm) however showed brittle behavior even in absence of hydrogen with similar intensity of percent fracture features at all distance from the notch, while presence of hydrogen intensified the overall percent brittle fractures with their intensities being highest close to the notch. Finally, the brittle fracture characteristics of the hydrogen embrittled samples were shown to be distinguishably different from that of the liquid nitrogen treated samples of same grain sizes and hardnesses.

Electrochemical hydrogen property improved in nano-structured perovskite oxide LaFeO3 for Ni/MH battery

Science.gov (United States)

Wang, Qiang; Deng, Gang; Chen, Zhiqian; Chen, Yungui; Cheng, Nanpu

2013-02-01

Perovskite oxide LaFeO3, as a novel candidate for the electrode of Ni/MH battery, holds high specific capacity and good cyclical durability at elevated temperatures. However, the poor electrochemical kinetics is a bottleneck for the application of this type of material. By use of nano-structured materials, there are greatly enhanced values of exchange current density I0 and hydrogen diffusion coefficient D, which resulted in an improvement of electrochemical kinetics, a much higher specific capacity and excellent stability during cycling for nano-structured LaFeO3. In theory, there is a significant possibility of further advancing the hydrogen reaction kinetics of perovskite type oxides for Ni/MH battery.

Advanced Electrochemical Technologies for Hydrogen Production by Alternative Thermochemical Cycles

Energy Technology Data Exchange (ETDEWEB)

Lvov, Serguei; Chung, Mike; Fedkin, Mark; Lewis, Michele; Balashov, Victor; Chalkova, Elena; Akinfiev, Nikolay; Stork, Carol; Davis, Thomas; Gadala-Maria, Francis; Stanford, Thomas; Weidner, John; Law, Victor; Prindle, John

2011-01-06

Hydrogen fuel is a potentially major solution to the problem of climate change, as well as addressing urban air pollution issues. But a key future challenge for hydrogen as a clean energy carrier is a sustainable, low-cost method of producing it in large capacities. Most of the world's hydrogen is currently derived from fossil fuels through some type of reforming processes. Nuclear hydrogen production is an emerging and promising alternative to the reforming processes for carbon-free hydrogen production in the future. This report presents the main results of a research program carried out by a NERI Consortium, which consisted of Penn State University (PSU) (lead), University of South Carolina (USC), Tulane University (TU), and Argonne National Laboratory (ANL). Thermochemical water decomposition is an emerging technology for large-scale production of hydrogen. Typically using two or more intermediate compounds, a sequence of chemical and physical processes split water into hydrogen and oxygen, without releasing any pollutants externally to the atmosphere. These intermediate compounds are recycled internally within a closed loop. While previous studies have identified over 200 possible thermochemical cycles, only a few have progressed beyond theoretical calculations to working experimental demonstrations that establish scientific and practical feasibility of the thermochemical processes. The Cu-Cl cycle has a significant advantage over other cycles due to lower temperature requirements – around 530 °C and below. As a result, it can be eventually linked with the Generation IV thermal power stations. Advantages of the Cu-Cl cycle over others include lower operating temperatures, ability to utilize low-grade waste heat to improve energy efficiency, and potentially lower cost materials. Another significant advantage is a relatively low voltage required for the electrochemical step (thus low electricity input). Other advantages include common chemical agents and

The electrochemical Peltier heat of the standard hydrogen electrode reaction

International Nuclear Information System (INIS)

Fang Zheng; Wang Shaofen; Zhang Zhenghua; Qiu Guanzhou

2008-01-01

A method for measuring the electrochemical Peltier heat (EPH) of a single electrode reaction has been developed and an absolute scale is suggested to obtain EPH of the standard hydrogen electrode. The scale is based on φ 0 * = 0 and ΔS 0 * = 0 for any electrode reaction at zero Kelvin, in accord with the third law of thermodynamics. The relationships between entropy, enthalpy and free energy changes on this scale and on the conventional scale are derived. Calorimetric experiments were made on the Fe(CN) 6 3- /Fe(CN) 6 4- system at five different concentrations at 298.15 K, and EPH for the standard hydrogen electrode reaction is obtained. EPHs and the entropy change on the absolute scale for the studied redox are linearly related to concentration of electrolyte. The reversible electric work is almost concentration independent in the range of concentration studied

Hydrogen from electrochemical reforming of C1–C3 alcohols using proton conducting membranes

NARCIS (Netherlands)

Sapountzi, F. M.; Tsampas, M. N.; Fredriksson, H. O. A.; Gracia, J. M.; Niemantsverdriet, J. W.

2017-01-01

This study investigates the production of hydrogen from the electrochemical reforming of short-chain alcohols (methanol, ethanol, iso-propanol) and their mixtures. High surface gas diffusion Pt/C electrodes were interfaced to a Nafion polymeric membrane. The assembly separated the two chambers of an

Electrochemical preparation and characteristics of Ni-Co-LaNi{sub 5} composite coatings as electrode materials for hydrogen evolution

Energy Technology Data Exchange (ETDEWEB)

Wu Gang; Li Ning; Dai Changsong; Zhou Derui

2004-02-15

Electrocatalytic activity for the hydrogen evolution reaction on Ni-Co-LaNi{sub 5} composite electrodes prepared by electrochemical codeposition technique was evaluated. The relationship between the current density for hydrogen evolution reaction and the amount of LaNi{sub 5} particles in Ni-Co baths is like the well-known 'volcano plot'. The Surface morphology and microstructure of Ni-Co-LaNi{sub 5} coatings were determined by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). The kinetic parameters were determined from electrochemical steady-state Tafel polarization and electrochemical impedance spectroscopy technology in 1 M NaOH solution. The values obtained for the apparent energies of activation are 32.48, 46.29 and 57.03 kJ mol{sup -1} for the Ni-Co-LaNi{sub 5}, Ni-Co and Ni electrodes, respectively. The hydrogen evolution reaction on Ni-Co-LaNi{sub 5} proceeds via Volmer-Tafel reaction route with the mixed rate determining characteristics. The composite coating Ni-Co-LaNi{sub 5} is catalytically more active than Ni and Ni-Co electrodes due to the increase in its real surface areas and the decrease in the apparent free energy of activation caused by the electrocatalytic synergistic effect of the Ni-Co alloys and the hydrogen storage intermetallic particles on the electrode surface.

The effect of co-deposition of hydrogen and metals on wall pumping in long duration plasma in TRIAM-1M

International Nuclear Information System (INIS)

Miyamoto, M.; Tokitani, M.; Tokunaga, K.; Fujiwara, T.; Yoshida, N.; Sakamoto, M.; Zushi, H.; Nagata, S.; Ono, K.

2005-01-01

The effect of co-deposition on recycling and wall pumping during long duration plasmas in TRIAM-1M has been studied. To examine the hydrogen retention on the all metal walls, material exposure experiments were carried out using an ultra-long discharge for about 72 min. After exposure to the plasma, the surface modification and hydrogen retention of the specimens were examined quantitatively by means of ion beam analysis techniques and transmission electron microscopy (TEM). Large amount of retained hydrogen were detected in the specimen exposed to the long duration discharge in TRIAM-1M. This amount was sufficient to explain the wall pumping in TRIAM-1M. A correlation was also observed between the thicknesses of the deposits and the amount of retained hydrogen. These results mean that the metallic deposited layer can trap a large amount of hydrogen and has a strong influence on hydrogen recycling similar to a carbon deposit

Pumping mechanisms in sputter-ion pumps low pressure operation

International Nuclear Information System (INIS)

Welch, K.M.

1991-01-01

It is shown that significant H 2 pumping occurs in the walls of triode pumps. Also, H 2 is pumped in the anode cells of sputter-ion pumps. This pumping occurs in a manner similar to that by which the inert gases are pumped. That is, H 2 is pumped in the walls of the anode cells by high energy neutral burial. Hydrogen in the pump walls and anodes limits the base pressure of the pump

Carbon catalysts for electrochemical hydrogen peroxide production in acidic media

DEFF Research Database (Denmark)

Čolić, Viktor; Yang, Sungeun; Révay, Zsolt

2018-01-01

Hydrogen peroxide is a commodity chemical, as it is an environmentally friendly oxidant. The electrochemical production of H2O2 from oxygen and water by the reduction of oxygen is of great interest, as it would allow the decentralized, on-site, production of pure H2O2. The ability to run...... the reaction in an acidic electrolyte with high performance is particularly important, as it would allow the use of polymer solid electrolytes and the production of pH-neutral hydrogen peroxide. Carbon catalysts, which are cheap, abundant, durable and can be highly selective show promise as potential catalysts...... for such systems. In this work, we examine the electrocatalytic performance and properties of seven commercially available carbon materials for H2O2 production by oxygen electroreduction. We show that the faradaic efficiencies for the reaction lie in a wide range of 18-82% for different carbon catalysts. In order...

Solutions for reducing dissolved hydrogen sulphide in the Black Sea by electrochemical oxidation

International Nuclear Information System (INIS)

Ciocanea, Adrian; Budea, Sanda; Radulescu, Gabriel

2007-01-01

Anaerobic disintegration of organic matter is a particular phenomenon in the Black Sea because of the set up of deposits of hydrogen sulphide, H 2 S, having high concentrations. The formation of such deposits is due to the absence of upward streams at depths larger than 100 meters. In Black Sea there is an oxic layer located roughly between 50 and 200 meters from which downwards begins the anoxic layer. If the equilibrium in Black Sea is not kept under control, an ecological disaster is possible. The first signals will be observed in surface waters, than, if the equilibrium is further disturbed the depth sulphides and the hydrogen sulphide deposits can develop up to inflammable and even explosive phases. This paper presents some solutions to reduce the hydrogen sulphide from Black Sea with a particular stress upon the electrochemical method. (authors)

Studies on the permeation of hydrogen through steam generator tubes at high temperatures using an electrochemical method

International Nuclear Information System (INIS)

Giraudeau, F.; Yang, L.; Steward, F.R.; DeBouvier, O.

1998-01-01

The permeation of hydrogen through steam generator tubes at high temperatures (∼ 300 degrees C) has been studied using an electrochemical technique. With this technique, hydrogen is generated on one side of the tube and monitored on the other side. The time for the hydrogen to reach the other side is used to determine the diffusion coefficient of hydrogen in the tube. Boundary conditions at the entry and exit sides have been investigated separately. Preliminary studies were performed on Stainless Steel 316 and Nickel Alloy 800 to better understand the influence of the solution chemistry on the electrochemical evolution of hydrogen. The surface phenomena effect and the trapping effect are discussed to account for differences observed in the permeation response. The hydrogen permeation through oxides at the exit side has been studied. Two nickel alloys (Alloy 800 and Alloy 600), materials widely used for steam generator tubes, have been investigated. The tubes were prefilmed using two different treatments. The oxides were formed in dry air at high temperatures (300 degrees C to 600 degrees C), or in humid gas at 300 degrees C. The diffusion coefficients at 300 degrees C in Stainless Steel 316 and Alloy 800 were determined to be of the order of 10 -6 - 10 -7 cm 2 /s for the bare metal. This is in agreement with results obtained by gas phase permeation techniques in the literature. (author)

Pumping mechanisms in sputter-ion pumps low pressure operation

International Nuclear Information System (INIS)

Welch, K.M.

1991-01-01

It is shown that significant H 2 pumping occurs in the walls of triode pumps. Also, H 2 is pumped in the anode cells of sputter-ion pumps. This pumping occurs in a manner similar to that by which the inert gases are pumped. That is, H 2 pumped in the walls of the anode cells by high energy neutral burial. Hydrogen in the pump walls and anodes limits the base pressure of the pump. 13 refs., 5 figs., 1 tab

Electrochemical hydrogen storage of Ti-V-based body-centered-cubic phase alloy surface-modified with AB5 nanoparticles

International Nuclear Information System (INIS)

Yu, X.B.; Walker, G.S.; Grant, D.M.; Wu, Z.; Xia, B.J.; Shen, J.

2005-01-01

A composite of Ti-V-based bcc phase alloy surface-modified with AB 5 nanoparticles was prepared by ball milling. The composite showed significantly improved electrochemical hydrogen release capacities. For example, the 30 min ball milled Ti-30V-15Mn-15Cr+10 wt %AB 5 showed a discharge capacity in the first cycle, at 353 K, of 886 mA h g -1 , corresponding to 3.38 wt % of hydrogen, with a 45 mA g -1 discharge current. It is thought that this high capacity is due to the enhanced electrochemical-catalytic activity from the alloy surface covered with AB 5 nanoparticles, which not only have better charge-discharge capacity themselves, acting as both an electrocatalyst and a microcurrent collector, but also result in the greatly enhanced hydrogen atomic diffusivities in the nanocrystalline relative to their conventional coarse-grained counterparts. These results provide new insight for use of Ti-V-based bcc phase alloy for high-energy batteries

Safety Evaluation for Packaging 101-SY Hydrogen Mitigation Mixer Pump package

International Nuclear Information System (INIS)

Carlstrom, R.F.

1994-01-01

This Safety Evaluation for Packaging (SEP) provides analysis and considered necessary to approve a one-time transfer of the 101-SY Hydrogen Mitigation Mixer Pump (HMMP). This SEP will demonstrate that the transfer of the HMMP in a new shipping container will provide an equivalent degree of safety as would be provided by packages meeting US Department of Transportation (DOT)/US Nuclear Regulatory Commission (NRC) requirements. This fulfills onsite, transportation requirements implemented by WHC-CM-2-14

Safety Evaluation for Packaging 101-SY Hydrogen Mitigation Mixer Pump package

Energy Technology Data Exchange (ETDEWEB)

Carlstrom, R.F.

1994-10-05

This Safety Evaluation for Packaging (SEP) provides analysis and considered necessary to approve a one-time transfer of the 101-SY Hydrogen Mitigation Mixer Pump (HMMP). This SEP will demonstrate that the transfer of the HMMP in a new shipping container will provide an equivalent degree of safety as would be provided by packages meeting US Department of Transportation (DOT)/US Nuclear Regulatory Commission (NRC) requirements. This fulfills onsite, transportation requirements implemented by WHC-CM-2-14.

In situ electrochemical XRD study of (de)hydrogenation of MgyTi100-y thin films

NARCIS (Netherlands)

Vermeulen, P.; Wondergem, H.J.; Graat, P.C.J.; Borsa, D.M.; Schreuders, H.; Dam, B.; Griessen, R.; Notten, P.H.L.

2008-01-01

X-ray diffraction and electrochemical (de)hydrogenation were performed in situ to monitor the symmetry of the unit cells of MgyTi100-y thin film alloys (with 70 to 90 at.% Mg) along the pressure composition isotherms at room temperature. The diffraction patterns show that the crystal structures of

In-situ electrochemical impedance spectroscopy measurements of zirconium alloy oxide conductivity: Relationship to hydrogen pickup

International Nuclear Information System (INIS)

Couet, Adrien; Motta, Arthur T.; Ambard, Antoine; Livigni, Didier

2017-01-01

Highlights: • In-situ electrochemistry on zirconium alloys in 360 °C pure water show oxide layer resistivity changes during corrosion. • A linear relationship is observed between oxide resistivity and instantaneous hydrogen pickup fraction. • The resistivity of the oxide layer formed on Zircaloy-4 (and thus its hydrogen pickup fraction) is higher than on Zr-2.5Nb. - Abstract: Hydrogen pickup during nuclear fuel cladding corrosion is a critical life-limiting degradation mechanism for nuclear fuel. Following a program dedicated to zirconium alloys, corrosion, it has been hypothesized that oxide electronic resistivity determines hydrogen pickup. In-situ electrochemical impedance spectroscopy experiments were performed on Zircaloy-4 and Zr-2.5Nb alloys in 360 °C water. The oxide resistivity was measured as function of time. The results show that as the oxide resistivity increases so does the hydrogen pickup fraction. The resistivity of the oxide layer formed on Zircaloy-4 is higher than on Zr-2.5Nb, resulting in a higher hydrogen pickup fraction of Zircaloy-4, compared to Zr-2.5Nb.

Low hydrogen containing amorphous carbon films - Growth and electrochemical properties as lithium battery anodes

Energy Technology Data Exchange (ETDEWEB)

Subramanian, V.; Masarapu, Charan; Wei, Bingqing [Department of Mechanical Engineering, University of Delaware, 130 Academy Street, Newark, DE 19716 (United States); Karabacak, Tansel [Department of Applied Science, University of Arkansas at Little Rock, 2801 South University Avenue, Little Rock, AR 72204 (United States); Teki, Ranganath [Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Lu, Toh-Ming [Department of Physics, Applied Physics, and Astronomy, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States)

2010-04-02

Amorphous carbon films were deposited successfully on Cu foils by DC magnetron sputtering technique. Electrochemical performance of the film as lithium battery anode was evaluated across Li metal at 0.2 C rate in a non-aqueous electrolyte. The discharge curves showed unusually low irreversible capacity in the first cycle with a reversible capacity of {proportional_to}810 mAh g{sup -1}, which is at least 2 times higher than that of graphitic carbon. For the first time we report here an amorphous carbon showing such a high reversibility in the first cycle, which is very much limited to the graphitic carbon. The deposited films were extensively characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and step profilometer for the structural and surface properties. The hydrogen content of the synthesized films was studied using residual gas analysis (RGA). The low hydrogen content and the low specific surface area of the synthesized amorphous carbon film are considered responsible for such a high first cycle columbic efficiency. The growth mechanism and the reasons for enhanced electrochemical performance of the carbon films are discussed. (author)

Low hydrogen containing amorphous carbon films-Growth and electrochemical properties as lithium battery anodes

Science.gov (United States)

Subramanian, V.; Karabacak, Tansel; Masarapu, Charan; Teki, Ranganath; Lu, Toh-Ming; Wei, Bingqing

Amorphous carbon films were deposited successfully on Cu foils by DC magnetron sputtering technique. Electrochemical performance of the film as lithium battery anode was evaluated across Li metal at 0.2 C rate in a non-aqueous electrolyte. The discharge curves showed unusually low irreversible capacity in the first cycle with a reversible capacity of ∼810 mAh g -1, which is at least 2 times higher than that of graphitic carbon. For the first time we report here an amorphous carbon showing such a high reversibility in the first cycle, which is very much limited to the graphitic carbon. The deposited films were extensively characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM) and step profilometer for the structural and surface properties. The hydrogen content of the synthesized films was studied using residual gas analysis (RGA). The low hydrogen content and the low specific surface area of the synthesized amorphous carbon film are considered responsible for such a high first cycle columbic efficiency. The growth mechanism and the reasons for enhanced electrochemical performance of the carbon films are discussed.

Standard practice for evaluation of hydrogen uptake, permeation, and transport in metals by an electrochemical technique

CERN Document Server

American Society for Testing and Materials. Philadelphia

1997-01-01

1.1 This practice gives a procedure for the evaluation of hydrogen uptake, permeation, and transport in metals using an electrochemical technique which was developed by Devanathan and Stachurski. While this practice is primarily intended for laboratory use, such measurements have been conducted in field or plant applications. Therefore, with proper adaptations, this practice can also be applied to such situations. 1.2 This practice describes calculation of an effective diffusivity of hydrogen atoms in a metal and for distinguishing reversible and irreversible trapping. 1.3 This practice specifies the method for evaluating hydrogen uptake in metals based on the steady-state hydrogen flux. 1.4 This practice gives guidance on preparation of specimens, control and monitoring of the environmental variables, test procedures, and possible analyses of results. 1.5 This practice can be applied in principle to all metals and alloys which have a high solubility for hydrogen, and for which the hydrogen permeation is ...

Cryosorption vacuum pumping under fusion reactor conditions

International Nuclear Information System (INIS)

Watson, J.S.; Fisher, P.W.

1977-01-01

Experiments are in progress on cryosorption pumping using a double-chevron pump with a molecular sieve pumping surface. Studies have been made with hydrogen, deuterium, helium, and deuterium-helium at 10 -7 to 3 x 10 -3 torr. Steady pumping speeds were observed for deuterium; above 10 -4 torr the speed increased with pressure until runaway occurred. At less than 10 -6 torr and low panel loading, hydrogen pumping speeds resemble those for deuterium. At higher pressures, the pump can function by condensation or sorption, and unsteady speeds are observed. Helium pumping is always by sorption, but regions of instability have been observed and defined. Deuterium-helium pumping tests showed that deuterium condensation on the panels prevents cryosorption of helium; however, compound pumps with separate panels for helium and hydrogen will be satisfactory

Hydrogen-based electrochemical energy storage

Science.gov (United States)

Simpson, Lin Jay

2013-08-06

An energy storage device (100) providing high storage densities via hydrogen storage. The device (100) includes a counter electrode (110), a storage electrode (130), and an ion conducting membrane (120) positioned between the counter electrode (110) and the storage electrode (130). The counter electrode (110) is formed of one or more materials with an affinity for hydrogen and includes an exchange matrix for elements/materials selected from the non-noble materials that have an affinity for hydrogen. The storage electrode (130) is loaded with hydrogen such as atomic or mono-hydrogen that is adsorbed by a hydrogen storage material such that the hydrogen (132, 134) may be stored with low chemical bonding. The hydrogen storage material is typically formed of a lightweight material such as carbon or boron with a network of passage-ways or intercalants for storing and conducting mono-hydrogen, protons, or the like. The hydrogen storage material may store at least ten percent by weight hydrogen (132, 134) at ambient temperature and pressure.

Electrochemical preparation of hematite nanostructured films for solar hydrogen production

Directory of Open Access Journals (Sweden)

Ebadzadeh T.

2012-10-01

Full Text Available Photoelectrochemical water splitting is a clean and promising technique for using a renewable source of energy, i.e., solar energy, to produce hydrogen. In this work electrochemical formation of iron oxyhydroxide and its conversion to hematite (α- Fe2O3 through thermal treatment have been studied. Oxyhydroxide iron compounds have been prepared onto SnO2/F covered glass substrate by potential cycling with two different potential sweep rate values; then calcined at 520 °C in air to obtain α-Fe2O3 nanostrutured films for their implementation as photoanode in a photoelectrochemical cell. X-ray diffraction analysis allowed finding that iron oxides films have nanocrystalline character. Scanning electron microscopy revealed that films have nanostructured morphology. The obtained results are discussed considering the influence of potential sweep rate employed during the preparation of iron oxyhydroxide film on optical, structural and morphological properties of hematite nanostructured films. Results show that films have acceptable characteristics as photoanode in a photoelectrochemical cell for hydrogen generation from water.

A reagentless non-enzymatic hydrogen peroxide sensor presented using electrochemically reduced graphene oxide modified glassy carbon electrode

Energy Technology Data Exchange (ETDEWEB)

Mutyala, Sankararao; Mathiyarasu, Jayaraman, E-mail: al_mathi@yahoo.com

2016-12-01

Herein, we report a simple, facile and reproducible non-enzymatic hydrogen peroxide (H{sub 2}O{sub 2}) sensor using electrochemically reduced graphene oxide (ERGO) modified glassy carbon electrode (GCE). The modified electrode was characterized by Fourier transform infrared (FT-IR), UV–Visible, scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. Cyclic voltammetric (CV) analysis revealed that ERGO/GCE exhibited virtuous charge transfer properties for a standard redox systems and showed excellent performance towards electroreduction of H{sub 2}O{sub 2}. Amperometric study using ERGO/GCE showed high sensitivity (0.3 μA/μM) and faster response upon the addition of H{sub 2}O{sub 2} at an applied potential of − 0.25 V vs. Ag/AgCl. The detection limit is assessed to be 0.7 μM (S/N = 3) and the time to reach a stable study state current is < 3 s for a linear range of H{sub 2}O{sub 2} concentration (1–16 μM). In addition, the modified electrode exhibited good reproducibility and long-term stability. - Graphical abstract: We presented a reagentless non-enzymatic hydrogen peroxide sensor using electrochemically reduced graphene oxide material. - Highlights: • A facile green procedure proposed for high quality graphene synthesis using electrochemical reduction of graphene oxide • A simple, facile and reagentless non-enzymatic hydrogen peroxide sensor developed using ERGO/GCE. • ERGO/GCE exhibited high sensitivity, selectivity and finite limit of detection for H{sub 2}O{sub 2} sensing at low overpotential. • ERGO/GCE exhibited long term stability and good reproducibility.

A reagentless non-enzymatic hydrogen peroxide sensor presented using electrochemically reduced graphene oxide modified glassy carbon electrode

International Nuclear Information System (INIS)

Mutyala, Sankararao; Mathiyarasu, Jayaraman

2016-01-01

Herein, we report a simple, facile and reproducible non-enzymatic hydrogen peroxide (H 2 O 2 ) sensor using electrochemically reduced graphene oxide (ERGO) modified glassy carbon electrode (GCE). The modified electrode was characterized by Fourier transform infrared (FT-IR), UV–Visible, scanning electron microscopy (SEM) and atomic force microscopy (AFM) techniques. Cyclic voltammetric (CV) analysis revealed that ERGO/GCE exhibited virtuous charge transfer properties for a standard redox systems and showed excellent performance towards electroreduction of H 2 O 2 . Amperometric study using ERGO/GCE showed high sensitivity (0.3 μA/μM) and faster response upon the addition of H 2 O 2 at an applied potential of − 0.25 V vs. Ag/AgCl. The detection limit is assessed to be 0.7 μM (S/N = 3) and the time to reach a stable study state current is < 3 s for a linear range of H 2 O 2 concentration (1–16 μM). In addition, the modified electrode exhibited good reproducibility and long-term stability. - Graphical abstract: We presented a reagentless non-enzymatic hydrogen peroxide sensor using electrochemically reduced graphene oxide material. - Highlights: • A facile green procedure proposed for high quality graphene synthesis using electrochemical reduction of graphene oxide • A simple, facile and reagentless non-enzymatic hydrogen peroxide sensor developed using ERGO/GCE. • ERGO/GCE exhibited high sensitivity, selectivity and finite limit of detection for H 2 O 2 sensing at low overpotential. • ERGO/GCE exhibited long term stability and good reproducibility.

Investigation on the Structure and Electrochemical Properties of La-Ce-Mg-Al-Ni Hydrogen Storage Alloy

Directory of Open Access Journals (Sweden)

Yuqing Qiao

2013-01-01

Full Text Available Structure and electrochemical characteristics of La0.96Ce0.04Mg0.15Al0.05Ni2.8 hydrogen storage alloy have been investigated. X-ray diffraction analyses reveal that the La0.96Ce0.04Mg0.15Al0.05Ni2.8 hydrogen storage alloy consisted of a (La, MgNi3 phase with the rhombohedral PuNi3-type structure and a LaNi5 phase with the hexagonal CaCu5-type structure. TEM shows that the alloy is multicrystal with a lattice space 0.187 nm. EDS analyse shows that the content of Mg is 3.48% (atom which coincide well with the designed composition of the electrode alloy. Electrochemical investigations show that the maximum discharge capacity of the alloy electrode is 325 mAh g−1. The alloy electrode has higher discharge capacity within the discharge current density span from 60 mA g−1 to 300 mA g−1. Electrochemical impedance spectroscopy measurements indicate that the charge transfer resistance RT on the alloy electrode surface and the calculated exchange current density I0 are 0.135 Ω and 1298 mA g−1, respectively; the better eletrochemical reaction kinetic of the alloy electrode may be responsible for the better high-rate dischargeability.

Hydrogen isotope technology

International Nuclear Information System (INIS)

Anon.

1980-01-01

Hydrogen pumping speeds on panels of molecular sieve types 5A and Na-Y were compared for a variety of sieve (and chevron) temperatures between 10 and 30 K. Although pumping speeds declined with time, probably because of the slow diffusion of hydrogen from the surface of the sieve crystals into the internal regions, the different sieve materials and operating conditions could be compared using time-averaged pump speeds. The (average) pumping speeds declined with increasing temperature. Under some conditions, the Na-Y sieve performed much better than the 5A sieve. Studies of the effect of small concentrations (approx. 4%) of hydrogen on helium pumping indicate that compound cryopumps in fusion reactors will not have to provide complete screening of hydrogen from helium panels. The concentrations of hydrogen did not lower effective helium pumping speeds or shorten the helium operating period between instabilities. Studies of tritium recovery from blankets of liquid lithium focused on design and construction of a flowing-lithium test system and on ultimate removal of tritium from yttrium sorbents. At 505 0 C, tritium release from yttrium behaves as a diffusion-controlled process, but the release rates are very low. Apparently, higher temperatures will be required for effective sorbent regeneration. An innovative technique for separating hydrogen isotopes by using bipolar electrolysis with permeable electrodes was analyzed to determine its potential usefulness in multistage separation

Efficient STEP (solar thermal electrochemical photo) production of hydrogen - an economic assessment

Energy Technology Data Exchange (ETDEWEB)

Licht, Stuart [Department of Chemistry, George Washington University, Ashburn, VA 20147 (United States); Solar Institute, George Washington University, Washington, DC 20052 (United States); Chitayat, Olivia; Bergmann, Harry; Dick, Andrew; Ayub, Hina [Solar Institute, George Washington University, Washington, DC 20052 (United States); Ghosh, Susanta [Department of Chemistry, George Washington University, Ashburn, VA 20147 (United States); Department of Chemistry, Visva-Bharati, Santiniketan (India)

2010-10-15

A consideration of the economic viability of hydrogen fuel production is important in the STEP (Solar Thermal Electrochemical Photo) production of hydrogen fuel. STEP is an innovative way to decrease costs and increase the efficiency of hydrogen fuel production, which is a synergistic process that can use concentrating photovoltaics (CPV) and solar thermal energy to drive a high temperature, low voltage, electrolysis (water-splitting), resulting in H{sub 2} at decreased energy and higher solar efficiency. This study provides evidence that the STEP system is an economically viable solution for the production of hydrogen. STEP occurs at both higher electrolysis and solar conversion efficiencies than conventional room temperature photovoltaic (PV) generation of hydrogen. This paper probes the economic viability of this process, by comparing four different systems: (1) 10% or (2) 14% flat plate PV driven aqueous alkaline electrolysis H{sub 2} production, (3) 25% CPV driven molten electrolysis H{sub 2} production, and (4) 35% CPV driven solid oxide electrolysis H{sub 2} production. The molten and solid oxide electrolysers are high temperature systems that can make use of light, normally discarded, for heating. This significantly increases system efficiency. Using levelized cost analysis, this study shows significant cost reduction using the STEP system. The total price per kg of hydrogen is shown to decrease from 5.74 to 4.96 to 3.01 to 2.61 with the four alternative systems. The advanced STEP plant requires less than one seventh of the land area of the 10% flat cell plant. To generate the 216 million kg H{sub 2}/year required by 1 million fuel cell vehicles, the 35% CPV driven solid oxide electrolysis requires a plant only 9.6 mi{sup 2} in area. While PV and electrolysis components dominate the cost of conventional PV generated hydrogen, they do not dominate the cost of the STEP-generated hydrogen. The lower cost of STEP hydrogen is driven by residual distribution and

Electrochemical energy generation

International Nuclear Information System (INIS)

Kreysa, G.; Juettner, K.

1993-01-01

The proceedings encompass 40 conference papers belonging to the following subject areas: Baseline and review papers; electrochemical fuel cells; batteries: Primary and secondary cells; electrochemical, regenerative systems for energy conversion; electrochemical hydrogen generation; electrochemistry for nuclear power plant; electrochemistry for spent nuclear fuel reprocessing; energy efficiency in electrochemical processes. There is an annex listing the authors and titles of the poster session, and compacts of the posters can be obtained from the office of the Gesellschaft Deutscher Chemiker, Abteilung Tagungen. (MM) [de

Cathodic electrochemical activation of Co3O4 nanoarrays: a smart strategy to significantly boost the hydrogen evolution activity.

Science.gov (United States)

Yang, Li; Zhou, Huang; Qin, Xin; Guo, Xiaodong; Cui, Guanwei; Asiri, Abdullah M; Sun, Xuping

2018-02-22

Co(hydro)oxides show unsatisfactory catalytic activity for the hydrogen evolution reaction (HER) in alkaline media, and it is thus highly desirable but still remains a challenge to design and develop Co(hydro)oxide derived materials as superb hydrogen-evolving catalysts using a facile, rapid and less energy-intensive method. Here, we propose a cathodic electrochemical activation strategy toward greatly boosted HER activity of a Co 3 O 4 nanoarray via room-temperature cathodic polarization in sodium hypophosphite solution. After activation, the overpotential significantly decreases from 260 to 73 mV to drive a geometrical catalytic current density of 10 mA cm -2 in 1.0 M KOH. Notably, this activated electrode also shows strong long-term electrochemical durability with the retention of its catalytic activity at 100 mA cm -2 for at least 40 h.

The electrochemical impedance of metal hydride electrodes

DEFF Research Database (Denmark)

Valøen, Lars Ole; Lasia, Andrzej; Jensen, Jens Oluf

2002-01-01

The electrochemical impedance responses for different laboratory type metal hydride electrodes were successfully modeled and fitted to experimental data for AB5 type hydrogen storage alloys as well as one MgNi type electrode. The models fitted the experimental data remarkably well. Several AC......, explaining the experimental impedances in a wide frequency range for electrodes of hydride forming materials mixed with copper powder, were obtained. Both charge transfer and spherical diffusion of hydrogen in the particles are important sub processes that govern the total rate of the electrochemical...... hydrogen absorption/desorption reaction. To approximate the experimental data, equations describing the current distribution in porous electrodes were needed. Indications of one or more parallel reduction/oxidation processes competing with the electrochemical hydrogen absorption/desorption reaction were...

Research and development on process components for hydrogen production. (1) Test-fabrication of sulfuric acid transfer pump

International Nuclear Information System (INIS)

Iwatsuki, Jin; Terada, Atsuhiko; Hino, Ryutaro; Kubo, Shinji; Onuki, Kaoru; Watanabe, Yutaka

2009-01-01

Japan Atomic Energy Agency has been conducting a research and development on hydrogen production system using High Temperature Gas-Cooled Reactor. As a part of this effort, thermochemical water-splitting cycle featuring iodine- and sulfur-compounds (IS process) is under development considering its potential of large-scale economical hydrogen production. The IS process constitutes very severe environments to the materials of construction because of the corrosive nature of process chemicals, especially of the high temperature acidic solutions of sulfuric acid and hydriodic acid dissolving iodine. Therefore, selection of the corrosion-resistant materials and development of the components have been the crucial subjects of process development. This paper concerns the sulfuric acid transfer pump. The development has been implemented of a pump for transporting concentrated sulfuric acid at temperatures of higher than 300degC and at elevated pressure. Recent progress of these activities will be reported. (author)

Carbon sheet pumping

International Nuclear Information System (INIS)

Ohyabu, N.; Sagara, A.; Kawamura, T.; Motojima, O.; Ono, T.

1993-07-01

A new hydrogen pumping scheme has been proposed which controls recycling of the particles for significant improvement of the energy confinement in toroidal magnetic fusion devices. In this scheme, a part of the vacuum vessel surface near the divertor is covered with carbon sheets of a large surface area. Before discharge initiation, the sheets are baked up to 700 ∼ 1000degC to remove the previously trapped hydrogen atoms. After being cooled down to below ∼ 200degC, the unsaturated carbon sheets trap high energy charge exchange hydrogen atoms effectively during a discharge and overall pumping efficiency can be as high as ∼ 50 %. (author)

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.

Hydrogen embrittlement, revisited by in situ electrochemical nanoindentation

Energy Technology Data Exchange (ETDEWEB)

Barnoush, Afrooz

2007-07-01

The fine scale mechanical probing capability of NI-AFM was used to examine hydrogen interaction with plasticity. To realize this, an electrochemical three electrode setup was incorporated into the NI-AFM. The developed ECNI-AFM is capable of performing nanoindentation as well as imaging surfaces inside electrolytes. The developed ECNI-AFM setup was used to examine the effect of cathodically charged hydrogen on dislocation nucleation in pure metals and alloys. It was shown that hydrogen reduces the pop-in load in all of the tested materials except Cu. The reduced pop-in load can be interpreted as the HELP mechanism. Classical dislocation theory was used to model the homogeneous dislocation nucleation and it was shown that H reduces the activation energy for dislocation nucleation in H sensitive metals which are not undergoing a phase transformation. The activation energy for dislocation nucleation is related to the material specific parameters; shear modulus {mu}, dislocation core radius {rho} and in the case of partial dislocation nucleation, stacking fault energy {gamma}. These material properties can be influenced by H resulting in a reduced activation energy for dislocation nucleation. The universality of cohesion in bulk metals relates the reduction of the shear modulus to the reduction of the cohesion, meaning HEDE mechanism. The increase in the core radius of a dislocation due to H is a direct evidence of decrease in dislocation line energy and H segregation on the dislocation line. In the case of partial dislocations, the H can segregate on to the stacking fault ribbon and decrease {gamma}. This inhibits the cross slip process and enhances the slip planarity. Thus, HELP and HEDE are the two sides of a coin resulting in H embrittlement. However depending on the experimental approach utilized to probe the H effect, either HELP or HEDE can be observed. In this study, however, by utilizing a proper experimental approach, it was possible to resolve the

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.

Fe-Substitution for Ni in Misch Metal-Based Superlattice Hydrogen Absorbing Alloys—Part 1. Structural, Hydrogen Storage, and Electrochemical Properties

Directory of Open Access Journals (Sweden)

Kwo-Hsiung Young

2016-11-01

Full Text Available The effects of Fe partially replacing Ni in a misch metal-based superlattice hydrogen absorbing alloy (HAA were studied. Addition of Fe increases the lattice constants and abundance of the main Ce2Ni7 phase, decreases the NdNi3 phase abundance, and increases the CaCu5 phase when the Fe content is above 2.3 at%. For the gaseous phase hydrogen storage (H-storage, Fe incorporation does not change the storage capacity or equilibrium pressure, but it does decrease the change in both entropy and enthalpy. With regard to electrochemistry, >2.3 at% Fe decreases both the full and high-rate discharge capacities due to the deterioration in both bulk transport (caused by decreased secondary phase abundance and consequent lower synergetic effect and surface electrochemical reaction (caused by the lower volume of the surface metallic Ni inclusions. In a low-temperature environment (−40 °C, although Fe increases the reactive surface area, it also severely hinders the ability of the surface catalytic, leading to a net increase in surface charge-transfer resistance. Even though Fe increases the abundance of the beneficial Ce2Ni7 phase with a trade-off for the relatively unfavorable NdNi3 phase, it also deteriorates the electrochemical performance due to a less active surface. Therefore, further surface treatment methods that are able to increase the surface catalytic ability in Fe-containing superlattice alloys and potentially reveal the positive contributions that Fe provides structurally are worth investigating in the future.

Experimental study of membrane pump for plasma devices

International Nuclear Information System (INIS)

Suzuki, Hajime; Ohyabu, Nobuyoshi; Nakamura, Yukio; Sagara, Akio; Motojima, Osamu; Livshits, A.; Notkin, M.; Busnyuk, A.; Komatsu, Kazuyuki

1998-01-01

Recycling control is a key to improve fusion plasma performance. The membrane pump has potential advantages for hydrogen pumping in fusion devices. However, there are unsolved issues for using membrane pump in LHD (Large Helical Device). The first issue is characteristics of the membrane pump under high incident hydrogen atom flux. The second issue is relationship between the surface condition and the pumping efficiency. Impurities from plasma may change the surface condition of the membrane. In order to solve these issues, a membrane pump system was fabricated and installed in a linear plasma device at NIFS (National Institute for Fusion Science). The membrane pump was successfully operated. (author)

Pumping speed of parallel-louvre-blind-type cryopumps

International Nuclear Information System (INIS)

Saho, Norihide; Ogata, Hisanao; Kunugi, Yosifumi; Uede, Taisei; Yamasita, Yasuo; Kawakami, Hiroyuki.

1993-01-01

As a new type of actual-sized cryopump with high pumping speed, a parallel-louvre-blind type cryopump of a rectangular cross section with opening distance B, width C and depth D, is proposed and is produced as a trial pump unit designed as actual size. The influence of pump depth size ratio R d (=D/B) and number of secondary cryopanels on the transmission probability P bc of the pump unit is calculated by Monte Carlo simulation, and the hydrogen pumping speed is measured by experiments. The following results are obtained. (1) The transmission probability of a cryopump designed with dimensional ratio of R d = 1.3 is calculated to be 0.66 at ratios of R c (=B/C) = 0.88, which means that hydrogen pumping speed of cryopumps of this size can attain 294 m 3 · s -1 /m 2 per opening area. (2) The real hydrogen pumping speed of the trial pump unit with 30 secondary cryopanels is measured as 295 m 3 · s -1 /m 2 . (author)

Dome load control and crane land path evaluation for Tank 241-SY-101 during hydrogen mitigation pump removal and installation

Energy Technology Data Exchange (ETDEWEB)

Weis, M.P.; Lawler, D.M.

1994-08-01

This report revisits and consolidates two analyses previously performed for the installation of the Hydrogen Mitigation Pump (HMT) pump. The first report determines, as a function of the crane-imposed dome load, the point to which the crane can encroach into the exclusion zone without exceeding the 50-ton limit. The second performs a load evaluation for the crane and the components in the load path (crane lift accessories and pump). In doing so, it determines the weakest component in the load path and the effect of this component on the allowable encroachment distance. Furthermore, the second report sets operational limits on the allowable load decrease (unload) during installation in the event the pump sticks in the riser. The analysis presented here expands on the latter subject by setting an operational limit on the amount of allowable load increase (overload) during pump removal in the event the pump sticks in the riser.

Vacuum pumping for controlled thermonuclear reactors

International Nuclear Information System (INIS)

Watson, J.S.; Fisher, P.W.

1976-01-01

Thermonuclear reactors impose unique vacuum pumping problems involving very high pumping speeds, handling of hazardous materials (tritium), extreme cleanliness requirements, and quantitative recovery of pumped materials. Two principal pumping systems are required for a fusion reactor, a main vacuum system for evacuating the torus and a vacuum system for removing unaccelerated deuterium from neutral beam injectors. The first system must pump hydrogen isotopes and helium while the neutral beam system can operate by pumping only hydrogen isotopes (perhaps only deuterium). The most promising pumping techniques for both systems appear to be cryopumps, but different cryopumping techniques can be considered for each system. The main vacuum system will have to include cryosorption pumps cooled to 4.2 0 K to pump helium, but the unburned deuterium-tritium and other impurities could be pumped with cryocondensation panels (4.2 0 K) or cryosorption panels at higher temperatures. Since pumping speeds will be limited by conductance through the ducts and thermal shields, the pumping performance for both systems will be similar, and other factors such as refrigeration costs are likely to determine the choice. The vacuum pumping system for neutral beam injectors probably will not need to pump helium, and either condensation or higher temperature sorption pumps can be used

Polymeric hydrogen diffusion barrier, high-pressure storage tank so equipped, method of fabricating a storage tank and method of preventing hydrogen diffusion

Science.gov (United States)

Lessing, Paul A [Idaho Falls, ID

2008-07-22

An electrochemically active hydrogen diffusion barrier which comprises an anode layer, a cathode layer, and an intermediate electrolyte layer, which is conductive to protons and substantially impermeable to hydrogen. A catalytic metal present in or adjacent to the anode layer catalyzes an electrochemical reaction that converts any hydrogen that diffuses through the electrolyte layer to protons and electrons. The protons and electrons are transported to the cathode layer and reacted to form hydrogen. The hydrogen diffusion barrier is applied to a polymeric substrate used in a storage tank to store hydrogen under high pressure. A storage tank equipped with the electrochemically active hydrogen diffusion barrier, a method of fabricating the storage tank, and a method of preventing hydrogen from diffusing out of a storage tank are also disclosed.

Formation of three-dimensional nano-porous silver films and application toward electrochemical detection of hydrogen peroxide

Energy Technology Data Exchange (ETDEWEB)

Fan, Junpeng [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Bian, Xiufang, E-mail: xfbian@sdu.edu.cn [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Niu, Yuchao [Department of Materials Science and Engineering, Shandong Jianzhu University, Fengming Road, Lingang Development Zone, Jinan 250101 (China); Bai, Yanwen; Xiao, Xinxin; Yang, Chuncheng; Yang, Jianfei; Yang, Jinyue [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Ministry of Education, Shandong University, Jinan 250061 (China)

2013-11-15

By using the chemically dealloying method, three-dimensional nano-porous silver films (3-D NPSFs) are fabricated into a novel sensor for detecting hydrogen peroxide. The precursor films are prepared by high vacuum magnetron co-sputtering. High-resolution transmission electron microscope (HRTEM) and scanning electron microscope (SEM) are taken to investigate the structure and the micro morphology of the precursor films and nano-porous films. We find that the precursor films are composed of glassy matrix and nanocrystallines. After dealloying, the films exhibit a combination of homogenously distributed pores and silver filaments, and exhibit an open, three dimensional bicontinuous interpenetrating ligament–channel structure. Thickness and morphology of the films can be easily controlled by the sputtering time and alloy composition of the precursor films, respectively. In addition, NPSFs show a good linear responding for the concentration of hydrogen peroxide in phosphate buffered solutions, which indicates NPSFs could be a promising electrochemical material for hydrogen peroxide detection.

ELECTROCHEMICAL SEPARATION AND CONCENTRATION OF HYDROGEN SULFIDE FROM GAS MIXTURES

Science.gov (United States)

Winnick, Jack; Sather, Norman F.; Huang, Hann S.

1984-10-30

A method of removing sulfur oxides of H.sub.2 S from high temperature gas mixtures (150.degree.-1000.degree. C.) is the subject of the present invention. An electrochemical cell is employed. The cell is provided with inert electrodes and an electrolyte which will provide anions compatible with the sulfur containing anions formed at the anode. The electrolyte is also selected to provide inert stable cations at the temperatures encountered. The gas mixture is passed by the cathode where the sulfur gases are converted to SO.sub.4 -- or, in the case of H.sub.2 S, to S--. The anions migrate to the anode where they are converted to a stable gaseous form at much greater concentration levels (>10X). Current flow may be effected by utilizing an external source of electrical energy or by passing a reducing gas such as hydrogen past the anode.

Hydrogen evolution reaction on electrodes with different PT/C loadings by electrochemical impedance spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Ortega-Chavez, L. [Inst. Tecnologico de Chihuahua 2, Chihuahua, Chih (Mexico); Ortega-Chavez, L.; Herrera-Peraza, E. [Centro de Investigacion en Materiales Avanzados, Chiuahua, Chih (Mexico); Verde, Y. [Inst. Tecnologico de Cancun, Cancun, Quintana Roo (Mexico)

2008-04-15

One of the most widely studied reactions in electrochemistry is the hydrogen evolution reaction (HER). HER is important for the development of water hydrolysis and fuel cell technologies. Because hydrogen-substrate interaction determines oxygen reduction efficiency, an understanding of the chemical and electronic state of hydrogen adsorbed on the electrocatalyst surface is required. Electrochemical impedance spectroscopy (EIS) is a proven highly efficient technique for interface characterization and kinetic parameter determination for different reactions carried out on interfaces. This article presented a study that utilized EIS for characterizing electrodes under HER by implementing a rotating disc electrode with different carbon supported platinum nanoparticles loadings and different potentials in acidic solutions. The results collected by EIS were analyzed in terms of equivalent circuits to calculate different parameters which were compared by statistical analysis. The study also considered the Volmer, Heyrovsky and Tafel steps in the HER reaction as well as a single electro-absorbed intermediate species. The article discussed the experimental set-up with reference to measurements, simulation and fitting. Parameters analysis using ANOVA were reviewed. It was concluded that an increase in impedance occurs when platinum loading decreases in both high and low frequencies. 22 refs., 1 tab., 5 figs.

Electrocatalytic oxygen reduction and hydrogen evolution reactions on phthalocyanine modified electrodes: Electrochemical, in situ spectroelectrochemical, and in situ electrocolorimetric monitoring

Energy Technology Data Exchange (ETDEWEB)

Koca, Atif, E-mail: akoca@eng.marmara.edu.tr [Department of Chemical Engineering, Faculty of Engineering, Marmara University, Goeztepe, 34722 Istanbul (Turkey); Kalkan, Ayfer; Bayir, Zehra Altuntas [Department of Chemistry, Technical University of Istanbul, Maslak, 34469 Istanbul (Turkey)

2011-06-30

Highlights: > Electrochemical and in situ spectroelectrochemical characterizations of the metallophthalocyanines were performed. > The presence of O{sub 2} influences both oxygen reduction reaction and the electrochemical behaviors of the complexes. > Homogeneous catalytic ORR process occurs via an 'inner sphere' chemical catalysis process. > CoPc and CuPc coated on a glassy carbon electrode decrease the overpotential of the working electrode for H{sup +} reduction. - Abstract: This study describes electrochemical, in situ spectroelectrochemical, and in situ electrocolorimetric monitoring of the electrocatalytic reduction of molecular oxygen and hydronium ion on the phthalocyanine-modified electrodes. For this purpose, electrochemical and in situ spectroelectrochemical characterizations of the metallophthalocyanines (MPc) bearing tetrakis-[4-((4'-trifluoromethyl)phenoxy)phenoxy] groups were performed. While CoPc gives both metal-based and ring-based redox processes, H{sub 2}Pc, ZnPc and CuPc show only ring-based electron transfer processes. In situ electrocolorimetric method was applied to investigate the color of the electrogenerated anionic and cationic forms of the complexes. The presence of O{sub 2} in the electrolyte system influences both oxygen reduction reaction and the electrochemical and spectral behaviors of the complexes, which indicate electrocatalytic activity of the complexes for the oxygen reduction reaction. Perchloric acid titrations monitored by voltammetry represent possible electrocatalytic activities of the complexes for hydrogen evolution reaction. CoPc and CuPc coated on a glassy carbon electrode decrease the overpotential of the working electrode for H{sup +} reduction. The nature of the metal center changes the electrocatalytic activities for hydrogen evolution reaction in aqueous solution. Although CuPc has an inactive metal center, its electrocatalytic activity is recorded more than CoPc for H{sup +} reduction in aqueous

Preliminary Study of a Piston Pump for Cryogenic Fluids

Science.gov (United States)

Biermann, Arnold E.; Kohl, Robert C.

1959-01-01

Preliminary data are presented covering the performance of a low-speed, five-cylinder piston pump designed for handling boiling hydrogen. This pump was designed for a flow of 55 gallons per minute at 240 rpm with a discharge pressure of 135 pounds per square inch. Tests were made using JP-4 fuel, liquid nitrogen, and liquid hydrogen. Pump delivery and endurance characteristics were satisfactory for the range of operation covered. In connection with the foregoing pump development, the cavitation characteristics of a preliminary visual model, glass-cylinder pump and of a simple reciprocating disk were studied. Subcooling of approximately 0.60 F was obtained from the cavitation produced by reciprocating a disk in boiling nitrogen and in boiling water. The subcooling obtained in a similar manner with liquid hydrogen was somewhat less.

Study of the electrochemical behavior of the niobium in relation to the hydrogen cyclical charge and uncharge; Estudo do comportamento eletroquimico do niobio em relacao ao carregamento e descarregamento ciclicos de hidrogenio

Energy Technology Data Exchange (ETDEWEB)

Silva, A.G.S.G. da; Ponte, H.A.; Pashchuk, A. [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Centro Politecnico. Lab. de Eletroquimica de Superficie e Corrosao (LESK)], e-mail: aleksantos@hotmail.com

2006-07-01

One of the greatest problems found in the oil industry is the control of the deterioration at the steels structures of the units that compose the process petroleum refine. This deterioration is related the mechanisms involving processes of hydrogen embrittlement. The work had as objective to study the electrochemical behavior of the niobium (Nb) with relation to the charging and uncharging of hydrogen, to evaluate the potential to use of the Nb in the construction of electrochemical hydrogen probes. For this study techniques of cronopotenciometry and potential of open circuit (OCP) for the pure Nb submitted the different hydrogen charging conditions had been used. The gotten partial results indicate the viability to use of the niobium as hydrogen probe, however, it is necessary one better understanding of the mechanisms of hydrogen interaction with the niobium. (author)

Electrochemical behavior of NixW1−x materials as catalyst for hydrogen evolution reaction in alkaline media

International Nuclear Information System (INIS)

Oliver-Tolentino, Miguel A.; Arce-Estrada, Elsa M.; Cortés-Escobedo, Claudia A.; Bolarín-Miro, Ana M.; Sánchez-De Jesús, Félix; González-Huerta, Rosa de G.; Manzo-Robledo, Arturo

2012-01-01

Highlights: ► The electrochemical techniques used in this study elucidated the Ni–W surface state. ► The Ni–W materials were effective for the hydrogen evolution reaction. ► The prepared alloys exhibited higher catalytic activity than their precursors. ► The preparation method is relatively simple and effective procedure. - Abstract: In the present work, results of electrochemical evaluation, as well as morphological and structural characterization of Ni x W 1−x materials with x = 0.77, 0.64, 0.4, 0.19 and 0.07 processed by means of high energy ball milling from high purity powders are presented. Also, the electrocatalytic performance on the hydrogen evolution reaction (HER) of the Ni x W 1−x materials evaluated by linear polarization and cyclic voltammetry techniques in alkaline media at room temperature is discussed. The structural and morphological characterization of the as-prepared materials was carried out using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results indicated a small-particle clusters and solid solution formation. According to the kinetics parameters the best electrocatalytic activity was observed at Ni 64 W 36 .

Proton conducting polymeric materials for hydrogen based electrochemical energy conversion technologies

DEFF Research Database (Denmark)

Aili, David

on the development and characterization of polymer based proton conducting membranes for operation at temperatures above 100 °C. The most frequently recurring experimental methods and techniques are described in Chapter 2. For PEM steam and liquid water electrolysis at temperatures up to 130 °C (Chapter 3 and 4...... and water electrolyzers. This thesis gives an overview of the principles and the current state-of-the-art technology of the hydrogen based electrochemical energy conversion technologies, with special emphasis on the PEM based water electrolyzers and fuel cells (Chapter 1). The fundamental thermodynamics...... of the recast Nafion® membranes at elevated temperature could be slightly improved by annealing the membrane in order to increase its degree of crystallinity. Short side chain (SSC) PFSA membranes such as Aquivion™ (Solvey Solexis), on the other hand, are generally characterized by a considerably higher degree...

Hydrogen evolution activity and electrochemical stability of selected transition metal carbides in concentrated phosphoric acid

DEFF Research Database (Denmark)

Tomás García, Antonio Luis; Jensen, Jens Oluf; Bjerrum, Niels J.

2014-01-01

phosphoric acid were investigated in a temperature range from 80 to 170°C. A significant dependence of the activities on temperature was observed for all five carbide samples. Through the entire temperature range Group 6 metal carbides showed higher activity than that of the Group 5 metal carbides......Alternative catalysts based on carbides of Group 5 (niobium and tantalum) and 6 (chromium, molybdenum and tungsten) metals were prepared as films on the metallic substrates. The electrochemical activities of these carbide electrodes towards the hydrogen evolution reaction (HER) in concentrated...

Controllable synthesis and electrochemical hydrogen storage properties of Sb₂Se₃ ultralong nanobelts with urchin-like structures.

Science.gov (United States)

Jin, Rencheng; Chen, Gang; Pei, Jian; Sun, Jingxue; Wang, Yang

2011-09-01

The controlled synthesis of one-dimensional and three-dimensional Sb(2)Se(3) nanostructures has been achieved by a facile solvothermal process in the presence of citric acid. By simply controlling the concentration of citric acid, the nucleation, growth direction and exposed facet can be readily tuned, which brings the different morphologies and nanostructures to the final products. The as-prepared products have been characterized by means of X-ray diffraction, field-emission scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM and selected area electron diffraction. Based on the electron microscope observations, a possible growth mechanism of Sb(2)Se(3) with distinctive morphologies including ultralong nanobelts, hierarchical urchin-like nanostructures is proposed and discussed in detail. The electrochemical hydrogen storage measurements reveal that the morphology plays a key role on the hydrogen storage capacity of Sb(2)Se(3) nanostructures. The Sb(2)Se(3) ultralong nanobelts with high percentage of {-111} facets exhibit higher hydrogen storage capacity (228.5 mA h g(-1)) and better cycle stability at room temperature.

Correlation between electrochemical impedance measurements and corrosion rate of magnesium investigated by real-time hydrogen measurement and optical imaging

OpenAIRE

Curioni, M.; Scenini, F.; Monetta, T.; Bellucci, F.

2015-01-01

The corrosion behaviour of magnesium in chloride-containing aqueous environment was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) performed simultaneously with real-time hydrogen evolution measurements and optical imaging of the corroding surface. The potentiodynamic investigation revealed substantial deviations from linearity in close proximity of the corrosion potential. In particular, differences in the slope of the current/potential curves w...

Test of the scroll pump in the JAERI Fuel Cleanup System in the Tritium Systems Test Assembly. JFCU scroll pump test and result, JFCU stand alone tritium test 2

Energy Technology Data Exchange (ETDEWEB)

Hayashi, Takumi; Konishi, Satoshi [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment; Ohira, Shigeru [and others

1993-03-01

In the JAERI Fuel Cleanup System (JFCU), major subsystem of the TSTA simulated fusion fuel loop, a Normetex Scroll pump is used to pump out hydrogen isotope gases from the palladium diffuser. The characteristics of the pump was measured with hydrogen isotopes and helium, in a closed loop. Compression ratio and ultimate pressure were strongly affected by the delivery pressure and the species of the gas. Particularly with H{sub 2} and D{sub 2}, additional metal bellows pump was proved to be needed to satisfy the process requirement. For hydrogen isotopes, pumping characteristics improves with the mass of the gas and similar pumping capability was obtained with pure T{sub 2} and helium. (author).

Electrochemical supramolecular recognition of hemin-carbon composites

Science.gov (United States)

Le, Hien Thi Ngoc; Jeong, Hae Kyung

2018-04-01

Hemin-graphite oxide-carbon nanotube (hemin-GO-CNT) and hemin-thermally reduced graphite oxide-carbon nanotube (hemin-TRGO-CNT) composites are synthesized and investigated for the electrochemical supramolecular recognition by electron transfer between biomolecules (dopamine and hydrogen peroxide) and the composite electrodes. Redox reaction mechanisms of two composites with dopamine and hydrogen peroxide are explained in detail by using cyclic voltammetry and differential pulse voltammetry. Hemin-TRGO-CNT displays higher electrochemical detection for dopamine and hydrogen peroxide than that of hemin-GO-CNT, exhibiting enhancement of the electron transfer due to the effective immobilization of redox couple of hemin (Fe2+/Fe3+) on the TRGO-CNT surface.

Final Technical Report for EE0006091: H2Pump Hydrogen Recycling System Demonstration

Energy Technology Data Exchange (ETDEWEB)

Staudt, Rhonda [H2Pump LLC, Latham, NY (United States)

2017-02-21

The objective of this project is to demonstrate the product readiness and to quantify the benefits and customer value proposition of H2Pump’s Hydrogen Recycling System (HRS-100™) by installing and analyzing the operation of multiple prototype 100-kg per day systems in real world customer locations. The data gathered will be used to measure reliability, demonstrate the value proposition to customers, and validate our business model. H2Pump will install, track and report multiple field demonstration systems in industrial heat treating and semi-conductor applications. The customer demonstrations will be used to develop case studies and showcase the benefits of the technology to drive market adoption.

The car on hydrogen: problems and solutions

International Nuclear Information System (INIS)

Koroteev, A.S.; Smolyarov, V.A.

2004-01-01

Development of the hydrogen power for transformation of the most power-consumption branch of the industry and transport into new power source - hydrogen as strategy direction for the reduction of pollution of environment and deficit of oil motor fuel is considered. On the basis of comparison of different type of electrochemical generators conclusion on advantages of electrochemical generator with solid polymer membrane was made. Different systems of hydrogen storage in automobile are considered. The system of the gaseous hydrogen storage at high pressure in cistern from composite materials is the most promise [ru

Synthesis of Biokerosene through Electrochemical Hydrogenation of Terpene Hydrocarbons from Turpentine Oil

Directory of Open Access Journals (Sweden)

Tedi Hudaya

2016-12-01

Full Text Available Indonesia possesses great potential for developing renewable resources as alternative fuels. For example, turpentine oil obtained from Pinus merkusii, which contains mostly monoterpene hydrocarbons (C10H16. The oil is highly suitable to be processed for biokerosene or even jet biofuel. It consists of hydrocarbons within the range of C10 to C15. However, it contains insufficient H and thus needs to be upgraded. In the present work, electrochemical hydrogenation was used for upgrading. In the electrochemical cell, stainless steel, silver, and carbon were used alternately for the anode, while copper and silver Raschig rings were used for the cathode. An electrolyte solution of cuprous ammonium formate was utilized not only as a source of H but also to draw the unsaturated hydrocarbons into the aqueous phase. The electrolyte : oil ratio (up to 2:1, electrolyte concentration (between 0.4 and 2 M and reaction time were varied throughout the experiments. The bromine number (unsaturation level of the turpentine oil, which was initially 1,86 (mole Br2/mole, was lowered significantly to 0.69-0.90. Promising increase of smoke point values were observed from 11 mm to 16-24 mm, indicating a higher H content of the processed oil, thus making it suitable as a substitute for petroleum kerosene.

Structure, temperature and frequency dependent electrical conductivity of oxidized and reduced electrochemically exfoliated graphite

Science.gov (United States)

Radoń, Adrian; Włodarczyk, Patryk; Łukowiec, Dariusz

2018-05-01

The article presents the influence of reduction by hydrogen in statu nascendi and modification by hydrogen peroxide on the structure and electrical conductivity of electrochemically exfoliated graphite. It was confirmed that the electrochemical exfoliation can be used to produce oxidized nanographite with an average number of 25 graphene layers. The modified electrochemical exfoliated graphite and reduced electrochemical exfoliated graphite were characterized by high thermal stability, what was associated with removing of labile oxygen-containing groups. The presence of oxygen-containing groups was confirmed using Fourier-transform infrared spectroscopy. Influence of chemical modification by hydrogen and hydrogen peroxide on the electrical conductivity was determined in wide frequency (0.1 Hz-10 kHz) and temperature range (-50 °C-100 °C). Material modified by hydrogen peroxide (0.29 mS/cm at 0 °C) had the lowest electrical conductivity. This can be associated with oxidation of unstable functional groups and was also confirmed by analysis of Raman spectra. The removal of oxygen-containing functional groups by hydrogen in statu nascendi resulted in a 1000-fold increase in the electrical conductivity compared to the electrochemical exfoliated graphite.

Photovoltaic and Hydrogen Plant Integrated with a Gas Heat Pump for Greenhouse Heating: A Mathematical Study

Directory of Open Access Journals (Sweden)

Alexandros Sotirios Anifantis

2018-02-01

Full Text Available Nowadays, the traditional energy sources used for greenhouse heating are fossil fuels such as LPG, diesel and natural gas. The global energy demand will continue to grow and alternative technologies need to be developed in order to improve the sustainability of crop production in protected environments. Innovative solutions are represented by renewable energy plants such as photovoltaic, wind and geothermal integrated systems, however, these technologies need to be connected to the power grid in order to store the energy produced. On agricultural land, power grids are not widespread and stand-alone renewable energy systems should be investigated especially for greenhouse applications. The aim of this research is to analyze, by means of a mathematical model, the energy efficiency of a photovoltaic (8.2 kW, hydrogen (2.5 kW and ground source gas heat pump (2.2 kW integrated in a stand-alone system used for heating an experimental greenhouse tunnel (48 m2 during the winter season. A yearlong energy performance analysis was conducted for three different types of greenhouse cover materials, a single layer polyethylene film, an air inflated-double layer polyethylene film, and a double acrylic or polycarbonate. The results of one year showed that the integrated system had a total energy efficiency of 14.6%. Starting from the electric energy supplied by the photovoltaic array, the total efficiency of the hydrogen and ground source gas heat pump system was 112% if the coefficient of the performance of the heat pump is equal to 5. The heating system increased the greenhouse air temperatures by 3–9 °C with respect to the external air temperatures, depending on the greenhouse cover material used.

Hydrogen pumping and release by graphite under high flux plasma bombardment

International Nuclear Information System (INIS)

Hirooka, Y.; Leung, W.K.; Conn, R.W.; Goebel, D.M.; Labombard, B.; Nygren, R.; Wilson, K.L.

1988-01-01

Inert gas (helium or argon) plasma bombardment has been found to increase the surface gas adsorptivity of isotropic graphite (POCO-graphite), which can then getter residual gases in a high vacuum system. The inert gas plasma bombardment was carried out at a flux ∼ 1 x 10 18 ions s -1 cm -2 to a fluence of the order of 10 21 ions/cm 2 and at temperatures around 800 degree C. The plasma bombarding energy was varied between 100 and 200 eV. The gettering speed of the activated graphite surface is estimated to be as large as 25 liters s -1 cm -2 at total pressures between 10 -6 and 10 -7 torr. The gettering capacity estimated is 0.025 torr-liter/cm 2 at room temperature. The gettering capability of graphite can be easily recovered by repeating inert gas plasma bombardment. The activated graphite surface exhibits a smooth, sponge-like morphology with significantly increased pore openings, which correlates with the observed increase in the surface gas adsorptivity. The activated graphite surface has been observed to pump hydrogen plasma particles as well. From calibrated H-alpha measurements, the dynamic hydrogen retention capacity is evaluated to be as large as 2 x 10 18 H/cm 2 at temperatures below 100 degree C and at a plasma bombarding energy of 300 eV

Study of the bipolar electrolysis of the tritiated water applied to the hydrogen isotopes separation by electrochemical permeation threw Pd-Ag alloy membranes

International Nuclear Information System (INIS)

Heinze, S.

2000-01-01

The objective of the study is to enrich waters of poor tritium concentration, by electrolysis in the same time of an hydrogen emission of low activity. In this framework the hydrogen electrochemical permeation threw Pd-Ag alloy membranes has been used. The first part of the study concerns the hydrogen and the deuterium diffusion threw these membranes. The activation and the thermal treatments influence have been studied. A relation between the membrane microstructure and the diffusion mechanism has been proposed. The second part of the study is devoted to the hydrogen gate mechanism determination in the membrane by impedance spectroscopy. The last part concerns the determination of the isotopic separation factor hydrogen-deuterium. Experimental results agree the calculated theoretical data. The operation of an operational membrane cell has been simulated and the process feasibility has been proved. (A.L.B.)

Electrochemical behavior of Ni{sub x}W{sub 1-x} materials as catalyst for hydrogen evolution reaction in alkaline media

Energy Technology Data Exchange (ETDEWEB)

Oliver-Tolentino, Miguel A. [UPIBI-IPN, Departamento de Ciencias Basicas, Av. Acueducto s/n, Barrio La Laguna, Col. Ticoman, Mexico D.F. 07340 (Mexico); Arce-Estrada, Elsa M. [ESIQIE-IPN Departamento de Ingenieria en Metalurgia y Materiales, UPALM, UPALM, Mexico D.F. 07738 (Mexico); Cortes-Escobedo, Claudia A. [Centro de Investigacion e Innovacion Tecnologica del IPN, Cda. Cecati s/n, Col. Sta. Catarina, CP 02250 Azcapotzalco D.F. (Mexico); Bolarin-Miro, Ana M.; Sanchez-De Jesus, Felix [Area Academica de Ciencias de la Tierra y Materiales, Universidad Autonoma del Estado de Hidalgo, CU, Carr. Pachuca-Tulancingo Km. 4.5, Mineral de la Reforma, CP 42184 Hidalgo (Mexico); Gonzalez-Huerta, Rosa de G. [ESIQIE-IPN, Departamento de Ingenieria Quimica - Laboratorio de Electroquimica y Corrosion, Edif. Z-5 3er piso, UPALM, Mexico D.F. 07738 (Mexico); Manzo-Robledo, Arturo, E-mail: amanzor@ipn.mx [ESIQIE-IPN, Departamento de Ingenieria Quimica - Laboratorio de Electroquimica y Corrosion, Edif. Z-5 3er piso, UPALM, Mexico D.F. 07738 (Mexico)

2012-09-25

Highlights: Black-Right-Pointing-Pointer The electrochemical techniques used in this study elucidated the Ni-W surface state. Black-Right-Pointing-Pointer The Ni-W materials were effective for the hydrogen evolution reaction. Black-Right-Pointing-Pointer The prepared alloys exhibited higher catalytic activity than their precursors. Black-Right-Pointing-Pointer The preparation method is relatively simple and effective procedure. - Abstract: In the present work, results of electrochemical evaluation, as well as morphological and structural characterization of Ni{sub x}W{sub 1-x} materials with x = 0.77, 0.64, 0.4, 0.19 and 0.07 processed by means of high energy ball milling from high purity powders are presented. Also, the electrocatalytic performance on the hydrogen evolution reaction (HER) of the Ni{sub x}W{sub 1-x} materials evaluated by linear polarization and cyclic voltammetry techniques in alkaline media at room temperature is discussed. The structural and morphological characterization of the as-prepared materials was carried out using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results indicated a small-particle clusters and solid solution formation. According to the kinetics parameters the best electrocatalytic activity was observed at Ni{sub 64}W{sub 36}.

Structurally Deformed MoS2 for Electrochemically Stable, Thermally Resistant, and Highly Efficient Hydrogen Evolution Reaction

KAUST Repository

Chen, Yen-Chang; Lu, Ang-Yu; Lu, Ping; Yang, Xiulin; Jiang, Chang-Ming; Mariano, Marina; Kaehr, Brian; Lin, Oliver; Taylor, André ; Sharp, Ian D.; Li, Lain-Jong; Chou, Stanley S.; Tung, Vincent

2017-01-01

The emerging molybdenum disulfide (MoS2) offers intriguing possibilities for realizing a transformative new catalyst for driving the hydrogen evolution reaction (HER). However, the trade-off between catalytic activity and long-term stability represents a formidable challenge and has not been extensively addressed. This study reports that metastable and temperature-sensitive chemically exfoliated MoS2 (ce-MoS2) can be made into electrochemically stable (5000 cycles), and thermally robust (300 °C) while maintaining synthetic scalability and excellent catalytic activity through physical-transformation into 3D structurally deformed nanostructures. The dimensional transition enabled by a high throughput electrohydrodynamic process provides highly accessible, and electrochemically active surface area and facilitates efficient transport across various interfaces. Meanwhile, the hierarchically strained morphology is found to improve electronic coupling between active sites and current collecting substrates without the need for selective engineering the electronically heterogeneous interfaces. Specifically, the synergistic combination of high strain load stemmed from capillarity-induced-self-crumpling and sulfur (S) vacancies intrinsic to chemical exfoliation enables simultaneous modulation of active site density and intrinsic HER activity regardless of continuous operation or elevated temperature. These results provide new insights into how catalytic activity, electrochemical-, and thermal stability can be concurrently enhanced through the physical transformation that is reminiscent of nature, in which properties of biological materials emerge from evolved dimensional transitions.

Structurally Deformed MoS2 for Electrochemically Stable, Thermally Resistant, and Highly Efficient Hydrogen Evolution Reaction

KAUST Repository

Chen, Yen-Chang

2017-10-12

The emerging molybdenum disulfide (MoS2) offers intriguing possibilities for realizing a transformative new catalyst for driving the hydrogen evolution reaction (HER). However, the trade-off between catalytic activity and long-term stability represents a formidable challenge and has not been extensively addressed. This study reports that metastable and temperature-sensitive chemically exfoliated MoS2 (ce-MoS2) can be made into electrochemically stable (5000 cycles), and thermally robust (300 °C) while maintaining synthetic scalability and excellent catalytic activity through physical-transformation into 3D structurally deformed nanostructures. The dimensional transition enabled by a high throughput electrohydrodynamic process provides highly accessible, and electrochemically active surface area and facilitates efficient transport across various interfaces. Meanwhile, the hierarchically strained morphology is found to improve electronic coupling between active sites and current collecting substrates without the need for selective engineering the electronically heterogeneous interfaces. Specifically, the synergistic combination of high strain load stemmed from capillarity-induced-self-crumpling and sulfur (S) vacancies intrinsic to chemical exfoliation enables simultaneous modulation of active site density and intrinsic HER activity regardless of continuous operation or elevated temperature. These results provide new insights into how catalytic activity, electrochemical-, and thermal stability can be concurrently enhanced through the physical transformation that is reminiscent of nature, in which properties of biological materials emerge from evolved dimensional transitions.

Mathematical modeling of the coupled transport and electrochemical reactions in solid oxide steam electrolyzer for hydrogen production

International Nuclear Information System (INIS)

Ni, Meng; Leung, Michael K.H.; Leung, Dennis Y.C.

2007-01-01

A mathematical model was developed to simulate the coupled transport/electrochemical reaction phenomena in a solid oxide steam electrolyzer (SOSE) at the micro-scale level. Ohm's law, dusty gas model (DGM), Darcy's law, and the generalized Butler Volmer equation were employed to determine the transport of electronic/ionic charges and gas species as well as the electrochemical reactions. Parametric analyses were performed to investigate the effects of operating parameters and micro-structural parameters on SOSE potential. The results substantiated the fact that SOSE potential could be effectively decreased by increasing the operating temperature. In addition, higher steam molar fraction would enhance the operation of SOSE with lower potential. The effect of particle sizes on SOSE potential was studied with due consideration on the SOSE activation and concentration overpotentials. Optimal particle sizes that could minimize the SOSE potential were obtained. It was also found that decreasing electrode porosity could monotonically decrease the SOSE potential. Besides, optimal values of volumetric fraction of electronic particles were found to minimize electrode total overpotentials. In order to optimize electrode microstructure to minimize SOSE electricity consumption, the concept of 'functionally graded materials (FGM)' was introduced to lower the SOSE potential. The advanced design of particle size graded SOSE was found effective for minimizing electrical energy consumption resulting in efficient SOSE hydrogen production. The micro-scale model was capable of predicting SOSE hydrogen production performance and would be a useful tool for design optimization

Spare mitigation/retrieval mixer pumps

International Nuclear Information System (INIS)

Taylor, S.

1995-01-01

This document presents the functional design criteria for design, analysis, fabrication, testing, and installation of a waste tank mixer pump. The mixer pump will be operated to eliminate the periodic releases of large quantities of flammable gas (e.g., hydrogen) from Hanford Site waste tanks and also to accommodate retrieval of tank waste

Indigenously developed large pumping speed cryoadsorption cryopump

International Nuclear Information System (INIS)

Gangradey, Ranjana; Mukherjee, Samiran Shanti; Agarwal, Jyoti

2015-01-01

Indigenous cryoadsorption cryopump with large pumping speeds for fusion reactor application has been developed at the Institute for Plasma Research (IPR). Towards its successful realization, technological bottlenecks were identified, studied and resolved. Hydroformed cryopanels were developed from concept leading to the design and product realization with successful technology transfer to the industry. This has led to the expertise for developing hydroformed panels for any desired shape, geometry and welding pattern. Activated sorbents were developed, characterized using an experimental set up which measures adsorption isotherms down to 4K for hydrogen and helium. Special techniques were evolved for coating sorbents on hydroformed cryopanels with suitable cryo-adhesives. Various arrangements of cryopanels at 4 K surrounded by 80 K shields and baffles (which are also hydroformed) were studied and optimized by transmission probability analysis using Monte Carlo techniques. CFD analysis was used to study the temperature distribution and flow analysis during the cryogen flow through the panels. Integration of the developed technologies to arrive at the final product was a challenging task and this was meticulously planned and executed. This resulted in a cryoadsorption cryopump offering pumping speeds as high as 50,000 to 70,000 1/s for helium and 1,50,000 1/s for hydrogen with a 3.2 m 2 of sorbent panel area. The first laboratory scale pump integrating the developed technologies was a Small Scale CryoPump (SSCP-01) with a pumping speed of 2,000 1/s for helium. Subsequently, Single Panel CryoPump (SPCP-01) with pumping speed 10,000 1/s for helium and a Multiple Panel CryoPump (MPCP-08) with a pumping speed of 70,000 1/s for helium and 1,50,000 1/s for hydrogen respectively were developed. This paper describes the efforts in realizing these products from laboratory to industrial scales. (author)

Production of bioelectricity, bio-hydrogen, high value chemicals and bioinspired nanomaterials by electrochemically active biofilms.

Science.gov (United States)

Kalathil, Shafeer; Khan, Mohammad Mansoob; Lee, Jintae; Cho, Moo Hwan

2013-11-01

Microorganisms naturally form biofilms on solid surfaces for their mutual benefits including protection from environmental stresses caused by contaminants, nutritional depletion or imbalances. The biofilms are normally dangerous to human health due to their inherited robustness. On the other hand, a recent study suggested that electrochemically active biofilms (EABs) generated by electrically active microorganisms have properties that can be used to catalyze or control the electrochemical reactions in a range of fields, such as bioenergy production, bioremediation, chemical/biological synthesis, bio-corrosion mitigation and biosensor development. EABs have attracted considerable attraction in bioelectrochemical systems (BESs), such as microbial fuel cells and microbial electrolysis cells, where they act as living bioanode or biocathode catalysts. Recently, it was reported that EABs can be used to synthesize metal nanoparticles and metal nanocomposites. The EAB-mediated synthesis of metal and metal-semiconductor nanocomposites is expected to provide a new avenue for the greener synthesis of nanomaterials with high efficiency and speed than other synthetic methods. This review covers the general introduction of EABs, as well as the applications of EABs in BESs, and the production of bio-hydrogen, high value chemicals and bio-inspired nanomaterials. Copyright © 2013 Elsevier Inc. All rights reserved.

Electrochemical impedance study of copper in phosphate buffered solution

International Nuclear Information System (INIS)

Salimon, J.; Mohamad, M.; Yamin, B.M.; Kalaji, M.

2003-01-01

The processes occurring on the copper electrode surface in phosphate buffered solution were investigated using the Electrochemical Impedance Spectroscopy. The electrochemical behaviors of copper through their charge transfer resistance and double-layer capacitance at the onset of the hydrogen evolution region and the anodic passivation layer formation and diffusion of copper species at anodic potential regions are discussed. The specific adsorption of anions (hydroxide and/or H/sub 2/PO/sub 4/) occurred at potential less negative than -0.9V. Adsorbed hydrogen appeared at hydrogen evolution region at potential range of -1.5 to -1.0 V. The deposition of insoluble copper species occurred at anodic potential regions. (author)

Hydrogen fuel. Uses

International Nuclear Information System (INIS)

Darkrim-Lamari, F.; Malbrunot, P.

2006-01-01

Hydrogen is a very energetic fuel which can be used in combustion to generate heat and mechanical energy or which can be used to generate electricity and heat through an electrochemical reaction with oxygen. This article deals with the energy conversion, the availability and safety problems linked with the use of hydrogen, and with the socio-economical consequences of a generalized use of hydrogen: 1 - hydrogen energy conversion: hydrogen engines, aerospace applications, fuel cells (principle, different types, domains of application); 2 - hydrogen energy availability: transport and storage (gas pipelines, liquid hydrogen, adsorbed and absorbed hydrogen in solid materials), service stations; 3 - hazards and safety: flammability, explosibility, storage and transport safety, standards and regulations; 4 - hydrogen economy; 5 - conclusion. (J.S.)

Dual-pump CARS measurements in a hydrogen diffusion flame in cross-flow with AC dielectric barrier discharge

Science.gov (United States)

Nishihara, Munetake; Freund, Jonathan B.; Glumac, Nick G.; Elliott, Gregory S.

2018-03-01

This paper presents dual-pump coherent anti-Stokes Raman scattering (CARS) measurements for simultaneous detection of flow temperature and relative concentration, applied to the characterization of a discharge-coupled reacting jet in a cross flow. The diagnostic is hydrogen Q-branch based, providing a much wider dynamic range compared to detection in the S-branch. For a previously developed dielectric barrier discharge, aligned co-axially with the fuel jet, OH planar laser induced fluorescence measurements show that the disturbance in the flame boundary leads to mixing enhancement. The H2-N2 dual-pump CARS measurement was used to map two-dimensional temperature distributions. The increase of the maximum temperature was up to 300 K, with 50% more H2 consumption, providing the reason for the decrease in the flame length by 25%. The increase of the relative H2O-H2 fraction was accompanied with a temperature increase, which indicates local equivalence ratios of below 1. The H2-O2 dual-pump measurements confirmed that the fuel-oxidizer ratios remain in the fuel-lean side at most of the probed locations.

Investigation of the Alkaline Electrochemical Interface and Development of Composite Metal/Metal-Oxides for Hydrogen and Oxygen Electrodes

Science.gov (United States)

Bates, Michael

Understanding the fundamentals of electrochemical interfaces will undoubtedly reveal a path forward towards a society based on clean and renewable energy. In particular, it has been proposed that hydrogen can play a major role as an energy carrier of the future. To fully utilize the clean energy potential of a hydrogen economy, it is vital to produce hydrogen via water electrolysis, thus avoiding co-production of CO2 inherent to reformate hydrogen. While significant research efforts elsewhere are focused on photo-chemical hydrogen production from water, the inherent low efficiency of this method would require a massive land-use footprint to achieve sufficient hydrogen production rates to integrate hydrogen into energy markets. Thus, this research has primarily focused on the water splitting reactions on base-metal catalysts in the alkaline environment. Development of high-performance base-metal catalysts will help move alkaline water electrolysis to the forefront of hydrogen production methods, and when paired with solar and wind energy production, represents a clean and renewable energy economy. In addition to the water electrolysis reactions, research was conducted to understand the de-activation of reversible hydrogen electrodes in the corrosive environment of the hydrogen-bromine redox flow battery. Redox flow batteries represent a promising energy storage option to overcome the intermittency challenge of wind and solar energy production methods. Optimization of modular and scalable energy storage technology will allow higher penetration of renewable wind and solar energy into the grid. In Chapter 1, an overview of renewable energy production methods and energy storage options is presented. In addition, the fundamentals of electrochemical analysis and physical characterization of the catalysts are discussed. Chapter 2 reports the development of a Ni-Cr/C electrocatalyst with unprecedented mass-activity for the hydrogen evolution reaction (HER) in alkaline

Surface treatment influences electrochemical stability of cpTi exposed to mouthwashes

International Nuclear Information System (INIS)

Beline, Thamara; Garcia, Camila S.; Ogawa, Erika S.; Marques, Isabella S.V.; Matos, Adaias O.; Sukotjo, Cortino; Mathew, Mathew T.

2016-01-01

The role of surface treatment on the electrochemical behavior of commercially pure titanium (cpTi) exposed to mouthwashes was tested. Seventy-five disks were divided into 15 groups according to surface treatment (machined, sandblasted with Al 2 O 3 , and acid etched) and electrolyte solution (artificial saliva — control, 0.12% chlorhexidine digluconate, 0.05% cetylpyridinium chloride, 0.2% sodium fluoride, and 1.5% hydrogen peroxide) (n = 5). Open-circuit-potential and electrochemical impedance spectroscopy were conducted at baseline and after 7 and 14 days of immersion in each solution. Potentiodynamic test and total weight loss of disks were performed after 14 days of immersion. Scanning electron microscopy, energy dispersive spectroscopy, white light interferometry and profilometry were conducted for surface characterization before and after the electrochemical tests. Sandblasting promoted the lowest polarization resistance (R p ) (P < .0001) and the highest capacitance (CPE) (P < .006), corrosion current density (I corr ) and corrosion rate (P < .0001). In contrast, acid etching increased R p and reduced CPE, independent to the mouthwash; while hydrogen peroxide reduced R p (P < .008) and increased I corr and corrosion rate (P < .0001). The highest CPE values were found for hydrogen peroxide and 0.2% sodium fluoride. Immersion for longer period improved the electrochemical stability of cpTi (P < .05). In conclusion, acid etching enhanced the electrochemical stability of cpTi. Hydrogen peroxide and sodium fluoride reduced the resistance to corrosion of cpTi, independent to the surface treatment. Chlorhexidine gluconate and cetylpyridinium chloride did not alter the corrosive behavior of cpTi. - Highlights: • Acid etching enhanced the electrochemical stability of cpTi. • Hydrogen peroxide and sodium fluoride reduced the corrosion resistance of cpTi. • Chlorhexidine gluconate and cetylpyridinium chloride can be safely used.

Surface treatment influences electrochemical stability of cpTi exposed to mouthwashes

Energy Technology Data Exchange (ETDEWEB)

Beline, Thamara [Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas (UNICAMP), Av Limeira, 901, Piracicaba, São Paulo 13414-903 (Brazil); IBTN/Br — Institute of Biomaterials, Tribocorrosion and Nanomedicine, Brazilian Branch (Brazil); Garcia, Camila S. [Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas (UNICAMP), Av Limeira, 901, Piracicaba, São Paulo 13414-903 (Brazil); Ogawa, Erika S. [Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas (UNICAMP), Av Limeira, 901, Piracicaba, São Paulo 13414-903 (Brazil); IBTN/Br — Institute of Biomaterials, Tribocorrosion and Nanomedicine, Brazilian Branch (Brazil); Marques, Isabella S.V. [Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas (UNICAMP), Av Limeira, 901, Piracicaba, São Paulo 13414-903 (Brazil); Matos, Adaias O. [Department of Prosthodontics and Periodontology, Piracicaba Dental School, University of Campinas (UNICAMP), Av Limeira, 901, Piracicaba, São Paulo 13414-903 (Brazil); IBTN/Br — Institute of Biomaterials, Tribocorrosion and Nanomedicine, Brazilian Branch (Brazil); Sukotjo, Cortino [Department of Restorative Dentistry, University of Illinois at Chicago, College of Dentistry, 801 S Paulina, Chicago, IL 60612 (United States); IBTN — Institute of Biomaterials, Tribocorrosion and Nanomedicine (United States); Mathew, Mathew T. [IBTN — Institute of Biomaterials, Tribocorrosion and Nanomedicine (United States); Department of Orthopedic Surgery, Rush University Medical Center, 1611 W Harrison, Chicago, IL 60612 (United States); and others

2016-02-01

The role of surface treatment on the electrochemical behavior of commercially pure titanium (cpTi) exposed to mouthwashes was tested. Seventy-five disks were divided into 15 groups according to surface treatment (machined, sandblasted with Al{sub 2}O{sub 3}, and acid etched) and electrolyte solution (artificial saliva — control, 0.12% chlorhexidine digluconate, 0.05% cetylpyridinium chloride, 0.2% sodium fluoride, and 1.5% hydrogen peroxide) (n = 5). Open-circuit-potential and electrochemical impedance spectroscopy were conducted at baseline and after 7 and 14 days of immersion in each solution. Potentiodynamic test and total weight loss of disks were performed after 14 days of immersion. Scanning electron microscopy, energy dispersive spectroscopy, white light interferometry and profilometry were conducted for surface characterization before and after the electrochemical tests. Sandblasting promoted the lowest polarization resistance (R{sub p}) (P < .0001) and the highest capacitance (CPE) (P < .006), corrosion current density (I{sub corr}) and corrosion rate (P < .0001). In contrast, acid etching increased R{sub p} and reduced CPE, independent to the mouthwash; while hydrogen peroxide reduced R{sub p} (P < .008) and increased I{sub corr} and corrosion rate (P < .0001). The highest CPE values were found for hydrogen peroxide and 0.2% sodium fluoride. Immersion for longer period improved the electrochemical stability of cpTi (P < .05). In conclusion, acid etching enhanced the electrochemical stability of cpTi. Hydrogen peroxide and sodium fluoride reduced the resistance to corrosion of cpTi, independent to the surface treatment. Chlorhexidine gluconate and cetylpyridinium chloride did not alter the corrosive behavior of cpTi. - Highlights: • Acid etching enhanced the electrochemical stability of cpTi. • Hydrogen peroxide and sodium fluoride reduced the corrosion resistance of cpTi. • Chlorhexidine gluconate and cetylpyridinium chloride can be safely used.

Electrochemically reduced water exerts superior reactive oxygen species scavenging activity in HT1080 cells than the equivalent level of hydrogen-dissolved water.

Directory of Open Access Journals (Sweden)

Takeki Hamasaki

Full Text Available Electrochemically reduced water (ERW is produced near a cathode during electrolysis and exhibits an alkaline pH, contains richly dissolved hydrogen, and contains a small amount of platinum nanoparticles. ERW has reactive oxygen species (ROS-scavenging activity and recent studies demonstrated that hydrogen-dissolved water exhibits ROS-scavenging activity. Thus, the antioxidative capacity of ERW is postulated to be dependent on the presence of hydrogen levels; however, there is no report verifying the role of dissolved hydrogen in ERW. In this report, we clarify whether the responsive factor for antioxidative activity in ERW is dissolved hydrogen. The intracellular ROS scavenging activity of ERW and hydrogen-dissolved water was tested by both fluorescent stain method and immuno spin trapping assay. We confirm that ERW possessed electrolysis intensity-dependent intracellular ROS-scavenging activity, and ERW exerts significantly superior ROS-scavenging activity in HT1080 cells than the equivalent level of hydrogen-dissolved water. ERW retained its ROS-scavenging activity after removal of dissolved hydrogen, but lost its activity when autoclaved. An oxygen radical absorbance capacity assay, the 2,2-diphenyl-1-picrylhydrazyl assay and chemiluminescence assay could not detect radical-scavenging activity in both ERW and hydrogen-dissolved water. These results indicate that ERW contains electrolysis-dependent hydrogen and an additional antioxidative factor predicted to be platinum nanoparticles.

Nuclear hydrogen production: re-examining the fusion option

International Nuclear Information System (INIS)

Baindur, S.

2007-01-01

This paper describes a scheme for nuclear hydrogen production by fusion. The basic idea is to use nuclear energy of the fuel (hydrogen plasma) to produce molecular hydrogen fro carbon-free hydrogen compounds. The hydrogen is then stored and utilized electrochemically in fuel cells or chemically as molecular hydrogen in internal combustion engines

Electrochemical behaviour of rhenium-graphite electrode

International Nuclear Information System (INIS)

Varypaev, V.N.; Krasikov, V.L.

1980-01-01

Electrochemical behaviour of combination electrode from graphite with electrodeposited thin coating of electrolytic rhenium is studied. Solution of 0.5 m NaCl+0.04 m AlCl 3 served as an electrolite. Polarization galvanostatic curves of hydrogen evolution upon electrodes with conditional rhenium thickness of 3.5 and 0.35 μm, 35 and 3.5 nm are obtained. Possibility of preparation of rhenium-graphite cathode with extremely low rhenium consume, electro-chemical properties of which are simu-lar to purely rhenium cathode is shown. Such electrode is characterized with stable in time low cathode potential of hydrogen evolution in chloride electrolyte and during cathode polarization it is not affected by corrosion

Electrochemical hydrogen storage alloys and batteries fabricated from Mg containing base alloys

Science.gov (United States)

Ovshinsky, Stanford R.; Fetcenko, Michael A.

1996-01-01

An electrochemical hydrogen storage material comprising: (Base Alloy).sub.a M.sub.b where, Base Alloy is an alloy of Mg and Ni in a ratio of from about 1:2 to about 2:1, preferably 1:1; M represents at least one modifier element chosen from the group consisting of Co, Mn, Al, Fe, Cu, Mo, W, Cr, V, Ti, Zr, Sn, Th, Si, Zn, Li, Cd, Na, Pb, La, Mm, and Ca; b is greater than 0.5, preferably 2.5, atomic percent and less than 30 atomic percent; and a+b=100 atomic percent. Preferably, the at least one modifier is chosen from the group consisting of Co, Mn, Al, Fe, and Cu and the total mass of the at least one modifier element is less than 25 atomic percent of the final composition. Most preferably, the total mass of said at least one modifier element is less than 20 atomic percent of the final composition.

Overview on recent developments in energy storage: Mechanical, electrochemical and hydrogen technologies

International Nuclear Information System (INIS)

Amirante, Riccardo; Cassone, Egidio; Distaso, Elia; Tamburrano, Paolo

2017-01-01

Highlights: • World energy demand is analyzed. • Promising energy storage systems are shown to explore their potentials. • Different storage are considered and compared. • The efficiency and costs of each are shown. • Easy guidelines for selection of energy storage are provided. - Abstract: Energy production is changing in the world because of the need to reduce greenhouse gas emissions, to reduce the dependence on carbon/fossil sources and to introduce renewable energy sources. Despite the great amount of scientific efforts, great care to energy storage systems is necessary to overcome the discontinuity in the renewable production. A wide variety of options and complex characteristic matrices make it difficult and so in this paper the authors show a clear picture of the available state-of-the-art technologies. The paper provides an overview of mechanical, electrochemical and hydrogen technologies, explaining operation principles, performing technical and economic features. Finally a schematic comparison among the potential utilizations of energy storage systems is presented.

Can aqueous hydrogen peroxide be used as a stand-alone energy source?

International Nuclear Information System (INIS)

Disselkamp, Robert S.

2010-01-01

A novel electrochemical scheme to convert a stand-alone supply of aqueous hydrogen peroxide into a fuel cell-ready stream of hydrogen gas plus aqueous hydrogen peroxide is described. The electrochemical cell, consisting of a solid base and solid acid electrocatalyst, together with a proton exchange membrane, comprise the system that converts aqueous hydrogen peroxide into separate gas streams of oxygen and hydrogen. Aqueous hydrogen peroxide is contained in the anode compartment only and exists in the region where oxygen gas is formed, whereas the cathode compartment is where hydrogen gas is generated and therefore exists in a reduced state. A near zero theoretical over-potential can be achieved by the choice of basicity and acidity of the electrode materials. The primary cost of the electrochemical cell is electrode construction and the aqueous hydrogen peroxide energy storage compound. Additional research effort is required to experimentally validate the concept and explore the full economic impact should initial studies, based on the design presented here, prove promising. (author)

Quorum sensing alters the microbial community of electrode-respiring bacteria and hydrogen scavengers toward improving hydrogen yield in microbial electrolysis cells

International Nuclear Information System (INIS)

Cai, Weiwei; Zhang, Zhaojing; Ren, Ge; Shen, Qiuxuan; Hou, Yanan; Ma, Anzhou; Deng, Ye; Wang, Aijie; Liu, Wenzong

2016-01-01

Highlights: • Enhanced hydrogen yield has been achieved with addition of AHL. • AHL regulated exoelectrogens resulting in electrochemical activity enhancement. • Microbial community shift in cathodic biofilm inhibited hydrogen loss. - Abstract: Quorum sensing has been widely applied to enhance the energy recovery of bioelectrochemical system as a sustainable pathway to enhance communication between cells and electrodes. However, how signalling molecules (acyl-homoserine lactones, AHLs) regulate the microbial community to improve hydrogen generation in microbial electrolysis cells (MECs) is not well understood, especially the subsequent influence on interspecies relationships among not only electrode-respiring bacteria but also hydrogen scavengers. Understanding AHL regulation in a complicated and actual biofilm system will be valuable for future applications of microbial electrochemical technology. Herein, we added short-chain AHLs (3OC6) to regulate the biofilm community on bio-electrodes in MECs. As a result, hydrogen yields were enhanced with AHL addition, increasing by 5.57%, 38.68%, and 81.82% with varied external voltages (0.8 V, 0.6 V, and 0.4 V, respectively). Accordingly, overall reactor performance was enhanced, including coulombic efficiency, electron recovery efficiency, and energy efficiency. Based on an electrochemical impedance spectra analysis, the structured biofilm under simple nutrient conditions (acetate) showed a lower internal resistance with AHL addition, indicating that the microbial communities were altered to enhance electron transfer between the biofilm and electrode. The change in the cathodic microbial structure with more electrochemically active bacteria and fewer hydrogen scavengers could contribute to a higher electron recovery and hydrogen yield with AHL addition. The regulation of the microbial community structure by AHLs represents a potential strategy to enhance electron transfer and hydrogen generation in

Influence of boron introduction on structure and electrochemical hydrogen storage properties of Ti–V-based alloys

International Nuclear Information System (INIS)

Qiu, Shujun; Huang, Jianling; Chu, Hailiang; Zou, Yongjin; Xiang, Cuili; Zhang, Huanzhi; Xu, Fen; Sun, Lixian; Zhou, Huaiying

2015-01-01

In order to improve the properties of Ti–V-based alloys in the electrochemical system, Ti 0.17 Zr 0.08 V 0.35 Cr 0.1 Ni 0.3 B x (x = 0–0.04) alloys were prepared and their structural and electrochemical performances had been systematically investigated in this study. XRD patterns show that they are mainly comprised of a C14 Laves phase and a body centered cubic (BCC) solid solution phase. The introduction of boron has little effect on the structure, while it remarkably influences the electrochemical performances. The cycle life of each electrode made from the studied alloy is obviously improved. For instance, the cycle retention after 200 charge–discharge cycles is more than 90%. Furthermore, high rate dischargeability (HRD) is also enhanced after boron introduction. It is also found that the charge-transfer reaction resistance R ct , the limiting current density I L, and the hydrogen diffusion coefficient D are first decreased and then increased with the increase of boron amount. Taking into consideration various factors, the introduction of boron in the alloy has an optimal value of x = 0.01. - Graphical abstract: Trace amounts of B element was introduced into Ti 0.17 Zr 0.08 V 0.35 Cr 0.1 Ni 0.3 alloys. XRD patterns show that the introduction of B has little effect on the structure, while it remarkably influences the electrochemical performances. The cycle life and the high rate dischargeability (HRD) are obviously improved. - Highlights: • Trace amounts of B element was introduced into Ti–V-based alloys. • Ti 0.17 Zr 0.08 V 0.35 Cr 0.1 Ni 0.3 B 0.01 has an optimal property. • At x = 0.01, C 200 /C max is 89.4% and HRD 800 is 72.5%

DFT based study of transition metal nano-clusters for electrochemical NH3 production

DEFF Research Database (Denmark)

Howalt, Jakob Geelmuyden; Bligaard, Thomas; Rossmeisl, Jan

2013-01-01

Theoretical studies of the possibility of producing ammonia electrochemically at ambient temperature and pressure without direct N2 dissociation are presented. Density functional theory calculations were used in combination with the computational standard hydrogen electrode to calculate the free...... for electrochemical ammonia production. The competing hydrogen evolution reaction has also been analyzed for comparison....

Controllable Electrochemical Activities by Oxidative Treatment toward Inner-Sphere Redox Systems at N-Doped Hydrogenated Amorphous Carbon Films

Directory of Open Access Journals (Sweden)

Yoriko Tanaka

2012-01-01

Full Text Available The electrochemical activity of the surface of Nitrogen-doped hydrogenated amorphous carbon thin films (a-CNH, N-doped DLC toward the inner sphere redox species is controllable by modifying the surface termination. At the oxygen plasma treated N-doped DLC surface (O-DLC, the surface functional groups containing carbon doubly bonded to oxygen (C=O, which improves adsorption of polar molecules, were generated. By oxidative treatment, the electron-transfer rate for dopamine (DA positively charged inner-sphere redox analyte could be improved at the N-doped DLC surface. For redox reaction of 2,4-dichlorophenol, which induces an inevitable fouling of the anode surface by forming passivating films, the DLC surfaces exhibited remarkably higher stability and reproducibility of the electrode performance. This is due to the electrochemical decomposition of the passive films without the interference of oxygen evolution by applying higher potential. The N-doped DLC film can offer benefits as the polarizable electrode surface with the higher reactivity and higher stability toward inner-sphere redox species. By making use of these controllable electrochemical reactivity at the O-DLC surface, the selective detection of DA in the mixed solution of DA and uric acid could be achieved.

Biomass derived porous nitrogen doped carbon for electrochemical devices

Directory of Open Access Journals (Sweden)

Litao Yan

2017-04-01

Full Text Available Biomass derived porous nanostructured nitrogen doped carbon (PNC has been extensively investigated as the electrode material for electrochemical catalytic reactions and rechargeable batteries. Biomass with and without containing nitrogen could be designed and optimized to prepare PNC via hydrothermal carbonization, pyrolysis, and other methods. The presence of nitrogen in carbon can provide more active sites for ion absorption, improve the electronic conductivity, increase the bonding between carbon and sulfur, and enhance the electrochemical catalytic reaction. The synthetic methods of natural biomass derived PNC, heteroatomic co- or tri-doping into biomass derived carbon and the application of biomass derived PNC in rechargeable Li/Na batteries, high energy density Li–S batteries, supercapacitors, metal-air batteries and electrochemical catalytic reaction (oxygen reduction and evolution reactions, hydrogen evolution reaction are summarized and discussed in this review. Biomass derived PNCs deliver high performance electrochemical storage properties for rechargeable batteries/supercapacitors and superior electrochemical catalytic performance toward hydrogen evolution, oxygen reduction and evolution, as promising electrodes for electrochemical devices including battery technologies, fuel cell and electrolyzer. Keywords: Biomass, Nitrogen doped carbon, Batteries, Fuel cell, Electrolyzer

Advanced hydrogen electrode for hydrogen-bromide battery

Science.gov (United States)

Kosek, Jack A.; Laconti, Anthony B.

1987-01-01

Binary platinum alloys are being developed as hydrogen electrocatalysts for use in a hydrogen bromide battery system. These alloys were varied in terms of alloy component mole ratio and heat treatment temperature. Electrocatalyst evaluation, performed in the absence and presence of bromide ion, includes floating half cell polarization studies, electrochemical surface area measurements, X ray diffraction analysis, scanning electron microscopy analysis and corrosion measurements. Results obtained to date indicate a platinum rich alloy has the best tolerance to bromide ion poisoning.

Structure and electrochemical hydrogen storage properties of Ti2Ni alloy synthesized by ball milling

International Nuclear Information System (INIS)

Hosni, B.; Li, X.; Khaldi, C.; ElKedim, O.; Lamloumi, J.

2014-01-01

Highlights: • The Ti 2 Ni alloy activation requires only one cycle of charge and discharge, regardless of the temperature. • By increasing the temperature the capacity loss, undergoes an increase and it is more pronounced for the 60 °C. • A good correlation is found between the evolutions of the different electrochemical parameters according to the temperature. - Abstract: The structure and the electrochemical hydrogen storage properties of amorphous Ti 2 Ni alloy synthesized by ball milling and used as an anode in nickel–metal hydride batteries were studied. Nominal Ti 2 Ni was synthesized under argon atmosphere at room temperature using a planetary high-energy ball mill. The structural and morphological characterization of the amorphous Ti 2 Ni alloy is carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical characterization of the Ti 2 Ni electrodes is carried out by the galvanostatic charging and discharging, the constant potential discharge, the open circuit potential and the potentiodynamic polarization techniques. The Ti 2 Ni alloy activation requires only one cycle of charge and discharge, regardless of the temperature. The electrochemical discharge capacity of the Ti 2 Ni alloy, during the first eight cycles, and at a temperature of 30 °C, remained practically unchanged and a good held cycling is observed. By increasing the temperature, the electrochemical discharge capacity loss after eight cycles undergoes an increase and it is more pronounced for the temperature 60 °C. At 30 °C, the anodic corrosion current density is 1 mA cm −2 and then it undergoes a rapid drop, remaining substantially constant (0.06 mA cm −2 ) in the range 40–60 °C, before undergoing a slight increase to 70 °C (0.3 mA cm −2 ). This variation is in good agreement with the maximum electrochemical discharge capacity values found for the different temperatures. By increasing the

Calculation of hydrogen outgassing rate of LHD by recombination limited model

International Nuclear Information System (INIS)

Akaishi, K.; Nakasuga, M.

2002-04-01

To simulate hydrogen outgassing in the plasma vacuum vessel of LHD, the recombination limited model is presented, where the time evolution of hydrogen concentration in the wall of the plasma vacuum vessel is described by a one-dimensional diffusion equation. The hydrogen outgassing rates when the plasma vacuum vessel is pumped down at room temperature and baked at 100 degC are calculated as a function of pumping time. The calculation shows that the hydrogen outgassing rate of the plasma vacuum vessel can be reduced at least by one order of magnitude due to pumping and baking. This prediction is consistent with the recent result of outgassing reduction observed in the pumping-down and baking of the plasma vacuum vessel in LHD. (author)

Characterization of ceramic materials for electrochemical hydrogen sensors

Energy Technology Data Exchange (ETDEWEB)

Serret, P.; Colominas, S. [Electrochemical Methods Laboratory - Analytical Chemistry Department ETS Institut Quimic de Sarria, Universitat Ramon Llull, Via Augusta, 390, 08017 Barcelona (Spain); Reyes, G. [Industrial Engineering Department ETS Institut Quimic de Sarria, Universitat Ramon Llull, Via Augusta, 390, 08017 Barcelona (Spain); Abella, J., E-mail: jordi.abella@iqs.es [Electrochemical Methods Laboratory - Analytical Chemistry Department ETS Institut Quimic de Sarria, Universitat Ramon Llull, Via Augusta, 390, 08017 Barcelona (Spain)

2011-10-15

Accurate and reliable tritium management is of basic importance for the correct operation conditions of the blanket tritium cycle. The Electrochemical Methods Lab at Institut Quimic de Sarria (IQS) is working in the design and development of tritium sensors, based on proton solid state electrolytes to be used in molten lithium-lead eutectic. Different solid electrolyte proton conductors have been synthesized (Sr{sub 3}CaZr{sub 0.9}Ta{sub 1.1}O{sub 8.55}, SrCe{sub 0.95}Yb{sub 0.05}O{sub 3-{alpha}}, CaZr{sub 0.9}In{sub 0.1}O{sub 3-{alpha}}, Ba{sub 3}(Ca{sub 1.18}Nb{sub 1.82})O{sub 9-{alpha}}) in order to be evaluated in a testing apparatus for hydrogen gas. Potentiometric measurements of the synthesized ceramic elements have been performed. In all experiments the working temperature was 500 {sup o}C. The sensors constructed using the proton conductor element Sr{sub 3}CaZr{sub 0.9}Ta{sub 1.1}O{sub 8.55} exhibited stable output potential and its value was close to the theoretical value calculated with the Nernst equation. When the proton conductor elements SrCe{sub 0.95}Yb{sub 0.05}O{sub 3-{alpha}} and CaZr{sub 0.9}In{sub 0.1}O{sub 3-{alpha}} and Ba{sub 3}(Ca{sub 1.18}Nb{sub 1.82})O{sub 9-{alpha}} were used a deviation higher than 100 mV between theoretical and experimental data was obtained.

The improvement of SiO2 nanotubes electrochemical behavior by hydrogen atmosphere thermal treatment

Science.gov (United States)

Spataru, Nicolae; Anastasescu, Crina; Radu, Mihai Marian; Balint, Ioan; Negrila, Catalin; Spataru, Tanta; Fujishima, Akira

2018-06-01

Highly defected SiO2 nanotubes (SiO2-NT) were obtained by a simple sol-gel procedure followed by calcination. Boron-doped diamond (BDD) polycrystalline films coated with SiO2-NT were used as working electrodes and, unexpectedly, cyclic voltammetric experiments have shown that the concentration of both positive and negative defects at the surface is high enough to enable redox processes involving positively charged Ru(bpy)32+/3+ to occur. Conversely, no electrochemical activity was put into evidence for Fe(CN)63-/4- species, most likely as a result of the strong electrostatic repulsion exerted by the negatively charged SiO2 surface. The concentration of surface defects was further increased by a subsequent thermal treatment in a hydrogen atmosphere which, as EIS measurements have shown, significantly promotes Ru(bpy)32+ anodic oxidation. Digital simulation of the voltammetric responses demonstrated that this treatment does not lead to a similar increase of the number of electron-donor sites. It was also found that methanol anodic oxidation at hydrogenated SiO2-NT-supported platinum results in Tafel slopes of 116-220 mV decade-1, comparable to those reported for both conventional PtRu and Pt-oxide catalysts.

Fabrication characteristics and hydrogenation behavior of hydrogen storage alloys for sealed Ni-MH batteries

Science.gov (United States)

Kim, Ho-Sung; Kim, Jeon Min; Kim, Tae-Won; Oh, Ik-Hyun; Choi, Jeon; Park, Choong Nyeon

2008-08-01

Hydrogen storage alloys based on LmNi4.2Co0.2Mn0.3Al0.3 were fabricated to study the equilibrium hydrogen pressure and electrochemical performance. The surface morphology and structure of the alloys were analyzed by SEM and XRD, and then the hydrogenation behaviors of all alloys were evaluated by PCT and electrochemical half-cell. We studied the hydrogenation behavior of the Lm-based alloy with changes in composition elements such as Mn, Al, and Co and investigated the optimal design for Lm-based alloy in a sealed battery system. As a result of studying the hydrogenation characterization of alloys with the substitution elements, hydrogen storage alloys such as LmNi3.75Co0.15Mn0.5Al0.3 and LmNi3.5Co0.5Mn0.5Al0.5 were obtained to correspond with the characteristics of a sealed battery with a higher capacity, long life cycle, lower internal pressure, and lower battery cost. The capacity preservation rate of LmNi3.5Co0.5Mn0.5Al0.5 was greatly improved to 92.7% (255 mAh/g) at 60 cycles, indicating a low equilibrium hydrogen pressure of 0.03 atm in PCT devices.

Rate equation modelling of the optically pumped spin-exchange source

International Nuclear Information System (INIS)

Stenger, J.; Rith, K.

1995-01-01

Sources for spin polarized hydrogen or deuterium, polarized via spin-exchange of a laser optically pumped alkali metal, can be modelled by rate equations. The rate equations for this type of source, operated either with hydrogen or deuterium, are given explicitly with the intention of providing a useful tool for further source optimization and understanding. Laser optical pumping of alkali metal, spin-exchange collisions of hydrogen or deuterium atoms with each other and with alkali metal atoms are included, as well as depolarization due to flow and wall collisions. (orig.)

Role of hydrogen in stress corrosion cracking

International Nuclear Information System (INIS)

Mehta, M.L.

1981-01-01

Electrochemical basis for differentiation between hydrogen embrittlement and active path corrosion or anodic dissolution crack growth mechanisms is examined. The consequences of recently demonstrated acidification in crack tip region irrespective of electrochemical conditions at the bulk surface of the sample are that the hydrogen can evolve within the crack and may be involved in the cracking process. There are basically three aspects of hydrogen involvement in stress corrosion cracking. In dissolution models crack propagation is assumed to be caused by anodic dissolution on the crack tip sustained by cathodic reduction of hydrogen from electrolyte within the crack. In hydrogen induced structural transformation models it is postulated that hydrogen is absorbed locally at the crack tip producing structural changes which facilitate crack propagation. In hydrogen embrittlement models hydrogen is absorbed by stressed metal from proton reduction from the electrolyte within the crack and there is interaction between lattice and hydrogen resulting in embrittlement of material at crack tip facilitating crack propagation. In the present paper, the role of hydrogen in stress corrosion crack growth in high strength steels, austenitic stainless steels, titanium alloys and high strength aluminium alloys is discussed. (author)

Electrochemical promotion of catalytic reactions with Pt/C (or Pt/Ru/C)//PBI catalysts

DEFF Research Database (Denmark)

Petrushina, Irina; Bjerrum, Niels; Bandur, Viktor

2007-01-01

The paper is an overview of the results of the investigation on electrochemical promotion of three catalytic reactions: methane oxidation with oxygen, NO reduction with hydrogen at 135 degrees C and Fischer-Tropsch synthesis (FTS) at 170 degrees C in the [CH4/O-2(or NO/H-2 or CO/H-2)/Ar//Pt(or Pt....../Ru)//PBI(H3PO4)/H-2, Ar] fuel cell. It has been shown that the partial methane oxidation to C2H2 and the C-2 selectivity were electrochemically promoted by the negative catalyst polarization. This was also the case in NO reduction with hydrogen for low NO and H-2 partial pressures. In both cases the catalytic...... reactions have been promoted by the electrochemically produced hydrogen. It has been found that the NO reduction with hydrogen on the Pt/PBI strongly depends on NO and hydrogen partial pressures in the working gas mixture. At higher NO and H-2 partial pressures the catalysis is promoted...

Electrochemically deposited Cu{sub 2}O cubic particles on boron doped diamond substrate as efficient photocathode for solar hydrogen generation

Energy Technology Data Exchange (ETDEWEB)

Mavrokefalos, Christos K. [Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA, England (United Kingdom); Hasan, Maksudul, E-mail: maksudul.hasan@chem.ox.ac.uk [Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA, England (United Kingdom); Tyndall National Institute, University College Cork, Lee Maltings, Cork (Ireland); Rohan, James F. [Tyndall National Institute, University College Cork, Lee Maltings, Cork (Ireland); Compton, Richard G. [Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, OX1 3QZ, England (United Kingdom); Foord, John S., E-mail: john.foord@chem.ox.ac.uk [Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, OX1 3TA, England (United Kingdom)

2017-06-30

Highlights: • Fabrication of low-cost photocathode by electrochemical method is described. • Boron-doped diamond is presented as catalyst support. • NiO nanoparticles on Cu{sub 2}O surface enhances photocurrent and electrode stability. • Synergy of metallic interaction between Cu and Ni leads to high efficiency. - Abstract: Herein, we report a novel photocathode for the water splitting reaction. The electrochemical deposition of Cu{sub 2}O particles on boron doped diamond (BDD) electrodes and the subsequent decoration with NiO nanoparticles by a dip coating method to act as co-catalyst for hydrogen evolution reaction is described. The morphology analysis by scanning electron microscope (SEM) revealed that Cu{sub 2}O particles are cubic and decorated sporadically with NiO nanoparticles. X-ray photoelectron spectroscopy (XPS) confirmed the electronic interaction at the interface between Cu{sub 2}O and NiO through a binding energy shift of the main Cu 2p peak. The photoelectrochemical (PEC) performance of NiO-Cu{sub 2}O/BDD showed a much higher current density (−0.33 mA/cm{sup 2}) and photoconversion efficiency (0.28%) compared to the unmodified Cu{sub 2}O/BDD electrode, which are only −0.12 mA/cm{sup 2} and 0.06%, respectively. The enhancement in PEC performance is attributable to the synergy of NiO as an electron conduction mediator leading to the enhanced charge separation and transfer to the reaction interface for hydrogen evolution as evidenced by electrochemical impedance spectroscopy (EIS) and charge carrier density calculation. Stability tests showed that the NiO nanoparticles loading content on Cu{sub 2}O surface is a crucial parameter in this regard.

Turbomolecular pumping systems for nuclear fusion devices in JAERI

International Nuclear Information System (INIS)

Ohga, Tokumichi; Arai, Takashi

1978-01-01

The turbomolecular pumping systems for the nuclear fusion devices JFT-2, JFT-2a and the injector test stands ITS-1, 2 and 3 in the Japan Atomic Energy Research Institute are mainly reported. For these vacuum systems, many requirements exist, such as oil free, large exhausting speed up to high pressure region (10 -3 Torr), compactness and easy operation and maintenance, etc., for the special usage. The outline of the systems and components, and the functions and the operational characteristics of the turbomolecular pumps are introduced. Concerning to the vacuum systems for JFT-2 and JFT-2a, the main system flow charts, the key specifications, the exhausting characteristic curves in case of starting from the atmospheric pressure for both JFT-2 and JFT-2a, and the conductance for hydrogen gas in the high vacuum side of JFT-2a are explained. As for the vacuum system for ITS-2, the main specification, the system flow chart, the main components, the functions, the conductance for hydrogen gas, the pumping characteristic curve, the starting characteristic of the turbomolecular pump, the exhausting speed for hydrogen gas and an example of mass spectrum are shown. The vacuum pressure obtained is almost 10 -5 -- 10 -6 torr for the three pumping systems. (Nakai, Y.)

When can Electrochemical Techniques give Reliable Corrosion Rates on Carbon Steel in Sulfide Media?

DEFF Research Database (Denmark)

Hilbert, Lisbeth Rischel; Hemmingsen, Tor; Nielsen, Lars Vendelbo

2005-01-01

in combination with ferrous sulfide corrosion products cover the steel surface. Corrosion rates can be overestimated by a factor of 10 to 100 with electrochemical techniques - both by linear polarization resistance (LPR) and electrochemical impedance spectroscopy (EIS). Oxygen entering the system accelerates......Effects of film formation on carbon steel in hydrogen sulfide media may corrupt corrosion rate monitoring by electrochemical techniques. Electrochemical data from hydrogen sulfide solutions, biological sulfide media and natural sulfide containing geothermal water have been collected and the process...... of film formation in sulfide solutions was followed by video. It can be shown that capacitative and diffusional effects due to porous reactive deposits tend to dominate the data resulting in unreliable corrosion rates measured by electrochemical techniques. The effect is strongly increased if biofilm...

Decentralized and direct solar hydrogen production: Towards a hydrogen economy in MENA region

Energy Technology Data Exchange (ETDEWEB)

Bensebaa, Farid; Khalfallah, Mohamed; Ouchene, Majid

2010-09-15

Hydrogen has certainly some advantages in spite of its high cost and low efficiency when compared to other energy vectors. Solar energy is an abundant, clean and renewable source of energy, currently competing with fossil fuel for water heating without subsidy. Photo-electrochemical, thermo-chemicals and photo-biological processes for hydrogen production processes have been demonstrated. These decentralised hydrogen production processes using directly solar energy do not require expensive hydrogen infrastructure for packaging and delivery in the short and medium terms. MENA region could certainly be considered a key area for a new start to a global deployment of hydrogen economy.

Process for electrochemically gasifying coal using electromagnetism

Science.gov (United States)

Botts, Thomas E.; Powell, James R.

1987-01-01

A process for electrochemically gasifying coal by establishing a flowing stream of coal particulate slurry, electrolyte and electrode members through a transverse magnetic field that has sufficient strength to polarize the electrode members, thereby causing them to operate in combination with the electrolyte to electrochemically reduce the coal particulate in the slurry. Such electrochemical reduction of the coal produces hydrogen and carbon dioxide at opposite ends of the polarized electrode members. Gas collection means are operated in conjunction with the process to collect the evolved gases as they rise from the slurry and electrolyte solution.

Electrochemical ammonia production on molybdenum nitride nanoclusters

DEFF Research Database (Denmark)

Howalt, Jakob Geelmuyden; Vegge, Tejs

2013-01-01

Theoretical investigations of electrochemical production of ammonia at ambient temperature and pressure on nitrogen covered molybdenum nanoparticles are presented. Density functional theory calculations are used in combination with the computational hydrogen electrode approach to calculate the free...... energy profile for electrochemical protonation of N2 and N adatoms on cuboctahedral Mo13 nanoparticles. Pathways for electrochemical ammonia production via direct protonation of N adatoms and N2 admolecules with an onset potential as low as -0.5 V and generally lower than -0.8 V on both a nitrogen...

SPE (tm) regenerative hydrogen/oxygen fuel cells for extraterrestrial surface and microgravity applications

Science.gov (United States)

Mcelroy, J. F.

1990-01-01

Viewgraphs on SPE regenerative hydrogen/oxygen fuel cells for extraterrestrial surface and microgravity applications are presented. Topics covered include: hydrogen-oxygen regenerative fuel cell energy storage system; electrochemical cell reactions; SPE cell voltage stability; passive water removal SPE fuel cell; fuel cell performance; SPE water electrolyzers; hydrophobic oxygen phase separator; hydrophilic/electrochemical hydrogen phase separator; and unitized regenerative fuel cell.

Electrochemical properties of N-doped hydrogenated amorphous carbon films fabricated by plasma-enhanced chemical vapor deposition methods

Energy Technology Data Exchange (ETDEWEB)

Tanaka, Yoriko; Furuta, Masahiro; Kuriyama, Koichi; Kuwabara, Ryosuke; Katsuki, Yukiko [Division of Environmental Science and Engineering, Graduate School of Science and Engineering, Yamaguchi University, 1677-1 Yoshida, Yamaguchi-shi, Yamaguchi 753-8512 (Japan); Kondo, Takeshi [Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science, 2641 Yamazaki, Noda 278-8510 (Japan); Fujishima, Akira [Kanagawa Advanced Science and Technology (KAST), 3-2-1, Sakato, Takatsu-ku, Kawasaki-shi, Kanagawa 213-0012 (Japan); Honda, Kensuke, E-mail: khonda@yamaguchi-u.ac.j [Division of Environmental Science and Engineering, Graduate School of Science and Engineering, Yamaguchi University, 1677-1 Yoshida, Yamaguchi-shi, Yamaguchi 753-8512 (Japan)

2011-01-01

Nitrogen-doped hydrogenated amorphous carbon thin films (a-C:N:H, N-doped DLC) were synthesized with microwave-assisted plasma-enhanced chemical vapor deposition widely used for DLC coating such as the inner surface of PET bottles. The electrochemical properties of N-doped DLC surfaces that can be useful in the application as an electrochemical sensor were investigated. N-doped DLC was easily fabricated using the vapor of nitrogen contained hydrocarbon as carbon and nitrogen source. A N/C ratio of resulting N-doped DLC films was 0.08 and atomic ratio of sp{sup 3}/sp{sup 2}-bonded carbons was 25/75. The electrical resistivity and optical gap were 0.695 {Omega} cm and 0.38 eV, respectively. N-doped DLC thin film was found to be an ideal polarizable electrode material with physical stability and chemical inertness. The film has a wide working potential range over 3 V, low double-layer capacitance, and high resistance to electrochemically induced corrosion in strong acid media, which were the same level as those for boron-doped diamond (BDD). The charge transfer rates for the inorganic redox species, Fe{sup 2+/3+} and Fe(CN){sub 6}{sup 4-/3-} at N-doped DLC were sufficiently high. The redox reaction of Ce{sup 2+/3+} with standard potential higher than H{sub 2}O/O{sub 2} were observed due to the wider potential window. At N-doped DLC, the change of the kinetics of Fe(CN){sub 6}{sup 3-/4-} by surface oxidation is different from that at BDD. The rate of Fe(CN){sub 6}{sup 3-/4-} was not varied before and after oxidative treatment on N-doped DLC includes sp{sup 2} carbons, which indicates high durability of the electrochemical activity against surface oxidation.

Structures and Electrochemical Hydrogen Storage Properties of the As-Spun RE-Mg-Ni-Co-Al-Based AB2-Type Alloys Applied to Ni-MH Battery

Science.gov (United States)

Zhang, Yanghuan; Yuan, Zeming; Shang, Hongwei; Li, Yaqin; Qi, Yan; Zhao, Dongliang

2017-05-01

In this paper, the La0.8- x Ce0.2Y x MgNi3.5Co0.4Al0.1 ( x = 0, 0.05, 0.1, 0.15, 0.2) alloys were synthesized via smelting and melt spinning. The effect of Y content on the structure and electrochemical hydrogen storage characteristics of the as-cast and spun alloys was investigated. The identifications of XRD and SEM demonstrate that the experimental alloys possess a major phase LaMgNi4 and a minor phase LaNi5. The variation of Y content results in an obvious transformation of the phase abundance rather than phase composition in the alloys, namely LaMgNi4 phase increases while LaNi5 phase decreases with Y content growing. Furthermore, the replacement of Y for La causes the lattice constants and cell volume to clearly decrease and markedly refines the alloy grains. The electrochemical tests reveal that these alloys can obtain the maximum values of discharge capacity at the first cycling without any activation needed. With Y content growing, the discharge capacity of the alloys obviously declines, but its cycle stability remarkably improves. Moreover, the electrochemical dynamics of the alloys, involving the high-rate discharge ability, hydrogen diffusion coefficient ( D), limiting current density ( I L), and charge transfer rate, initially augment and then decrease with rising Y content.

A metal foil vacuum pump for the fuel cycle of fusion power plants

Energy Technology Data Exchange (ETDEWEB)

Giegerich, Thomas; Day, Christian [Karlsruher Institut fuer Technologie (KIT), Institut fuer Technische Physik (ITEP), Eggenstein-Leopoldshafen (Germany)

2013-07-01

At KIT Karlsruhe, a new vacuum pump based on the physical principle of superpermeation is under development. This metal foil pump shall be used in the fuel cycle of a fusion reactors and forms the central part of the Direct Internal Recycling concept (DIR), a shortcut between the machine exhaust pumping and the fuelling systems. This vacuum pump simplifies the fusion fuel cycle dramatically and provides two major functions simultaneously: A separating and pumping function. It separates a hydrogen isotopes and impurities containing gas flow sharply into a pure H-isotopes flow that is also being compressed. The remaining impurity enriched gas flow passes the pump without being pumped. For superpermeability, a source of molecular hydrogen is needed. This can be achieved by different methods inside of the pump. Most important are plasma based or hot rod (atomizer) based methods. In this talk, the physical working principle and the modeling of this pump is presented and the development towards a technical separator pumping module is shown up.

Effect of piperidones on hydrogen permeation and corrosion ...

Indian Academy of Sciences (India)

corrosion inhibition. 3.5 Hydrogen permeation measurements. Hydrogen can enter into the metal during various industrial operations like melting, heat treatment, or pickling and electrochemical processes such as cathodic cleaning and electrolytic machining. Of the various sources of entry of hydrogen into the metal,.

Electrochemical energy storage for renewable sources and grid balancing

CERN Document Server

Moseley, Patrick T

2015-01-01

Electricity from renewable sources of energy is plagued by fluctuations (due to variations in wind strength or the intensity of insolation) resulting in a lack of stability if the energy supplied from such sources is used in 'real time'. An important solution to this problem is to store the energy electrochemically (in a secondary battery or in hydrogen and its derivatives) and to make use of it in a controlled fashion at some time after it has been initially gathered and stored. Electrochemical battery storage systems are the major technologies for decentralized storage systems and hydrogen

A facile approach to prepare crumpled CoTMPyP/electrochemically reduced graphene oxide nanohybrid as an efficient electrocatalyst for hydrogen evolution reaction

Energy Technology Data Exchange (ETDEWEB)

Ma, Juanjuan, E-mail: majj0518@hotmail.com [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang 222005 (China); School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore (Singapore); Liu, Lin; Chen, Qian; Yang, Min [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang 222005 (China); Wang, Danping [School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore (Singapore); Tong, Zhiwei [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang 222005 (China); Chen, Zhong, E-mail: aszchen@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, 639798, Singapore (Singapore)

2017-03-31

Highlights: • Crumpled CoTMPyP/ERGO hybrid was successfully prepared by a facile two-step process. • CoTMPyP nanoaggregates are homogeneously distributed over the graphene surface. • CoTMPyP/ERGO hybrid film shows good electrocatalytic activity and stability for HER. - Abstract: Elaborate design and synthesis of efficient and stable non-Pt electrocatalysts for some renewable energy related conversion/storage processes are one of the major goals of sustainable chemistry. Herein, we report a facile method to fabricate Co porphyrin functionalized electrochemically reduced graphene oxide (CoTMPyP/ERGO) thin film by direct assembly of oppositely charged tetrakis(N-methylpyridyl) porphyrinato cobalt (CoTMPyP) and GO nanosheets under mild conditions followed by an electrochemical reduction procedure. STEM analysis confirms that CoTMPyP nanoaggregates are homogeneously distributed over the graphene surface. The electrochemical properties of CoTMPyP/ERGO were investigated by cyclic voltammetry, linear sweep voltammetry and electrochemical impedance spectroscopy. The results demonstrate that CoTMPyP/ERGO nanohybrid film can serve as excellent electrocatalyst for hydrogen evolution in alkaline solution with high activity and stability. The intimate contact and efficient electron transfer between CoTMPyP and ERGO, as well as the crumpled structure, contribute to the improvement of the electrocatalytic performance.

Design of an isopropanol–acetone–hydrogen chemical heat pump with exothermic reactors in series

International Nuclear Information System (INIS)

Xu, Min; Duan, Yanjun; Xin, Fang; Huai, Xiulan; Li, Xunfeng

2014-01-01

The isopropanol–acetone–hydrogen chemical heat pump system with a series of exothermic reactors in which the reaction temperatures decrease successively is proposed. This system shows the better energy performances as compared with the traditional system with a single exothermic reactor, especially when the higher upgraded temperature is need. At the same amounts of the heat released, the work input of the compressor and the heater are both reduced notably. The results indicate that the advantages of the IAH-CHP system with exothermic reactors in series are obvious. - Highlights: • We propose the IAH-CHP system with exothermic reactors in series. • The COP and exergy efficiency of the system increase by 7.6% and 10.3% respectively. • The work input of the system is reduced notably at the same quantity of heat released

Electrochemical properties of LaMO3 (M=Co or Fe) as the negative electrode in a hydrogen battery

Science.gov (United States)

Lim, D.-K.; Im, H.-N.; Kim, J.; Song, S.-J.

2013-01-01

Undoped orthorthombic LaFeO3 and monoclinic LaCoO3 oxides were selected as an anode material for Ni-H battery due to their high electron conductivity by multivalent transition status of B-site cation. Both groups of oxides were prepared by a conventional solid-state reaction method, and their electrochemical charge/discharge properties were investigated. The electrochemical kinetic properties, exchange current density, and proton diffusivity were also extracted using linear polarization measurement and the potential-step method. X-ray photoelectron spectroscopy (XPS) analysis was used to measure the oxidation state of the transition metal in the specimens. A non-linear least-square fitting deconvoluted the peaks, suggesting that the valence state of Fe and Co in the sample was mainly +3. The hydrogen diffusion rate was also estimated using the potential-step method, giving 5.42×10-16 and 5.72×10-16 cm2 s-1 for LaCoO3 and LaFeO3, respectively which are an order of magnitude larger than that of Sr doped LaFeO3 oxide electrodes.

Improving corrosion resistance of magnesium-based alloys by surface modification with hydrogen by electrochemical ion reduction (EIR) and by plasma immersion ion implantation (PIII)

Energy Technology Data Exchange (ETDEWEB)

Bakkar, A. [Institut fuer Materialpruefung und Werkstofftechnik, Dr. Doelling und Dr. Neubert GmbH, Freiberger Strasse 1, 38678 Clausthal (Germany); Department of Metallurgy and Materials Engineering, Suez Canal University, P.O. Box 43721, Suez (Egypt); Neubert, V. [Institut fuer Materialpruefung und Werkstofftechnik, Dr. Doelling und Dr. Neubert GmbH, Freiberger Strasse 1, 38678 Clausthal (Germany)]. E-mail: volkmar.neubert@tu-clausthal.de

2005-05-01

Magnesium-based hydrides are well known that they have a high hydrogen-storage capacity. In this study, two different methods have been provided for hydrogen surface modification of high purity magnesium (hp Mg) and AZ91 magnesium alloy. One was electrochemical ion reduction (EIR) of hydrogen from an alkaline electrolyte on such Mg-based cathode. The other was plasma immersion ion implantation (PIII or PI{sup 3}) into Mg-based substrate. The depth profile of H-modified surfaces was described by Auger electron spectroscopy (AES) and by secondary ion mass spectrometry (SIMS) measurements. Corrosion testing was carried out in Avesta cell by potentiodynamic polarisation in chloride-containing aqueous solutions of pH 7 and pH 12. A greatly significant improvement in the corrosion resistance of H-modified surfaces was verified.

Improving corrosion resistance of magnesium-based alloys by surface modification with hydrogen by electrochemical ion reduction (EIR) and by plasma immersion ion implantation (PIII)

International Nuclear Information System (INIS)

Bakkar, A.; Neubert, V.

2005-01-01

Magnesium-based hydrides are well known that they have a high hydrogen-storage capacity. In this study, two different methods have been provided for hydrogen surface modification of high purity magnesium (hp Mg) and AZ91 magnesium alloy. One was electrochemical ion reduction (EIR) of hydrogen from an alkaline electrolyte on such Mg-based cathode. The other was plasma immersion ion implantation (PIII or PI 3 ) into Mg-based substrate. The depth profile of H-modified surfaces was described by Auger electron spectroscopy (AES) and by secondary ion mass spectrometry (SIMS) measurements. Corrosion testing was carried out in Avesta cell by potentiodynamic polarisation in chloride-containing aqueous solutions of pH 7 and pH 12. A greatly significant improvement in the corrosion resistance of H-modified surfaces was verified

Structure and electrochemical hydrogen storage properties of Ti{sub 2}Ni alloy synthesized by ball milling

Energy Technology Data Exchange (ETDEWEB)

Hosni, B. [Equipe des Hydrures Métalliques, Laboratoire de Mécanique, Matériaux et Procédés, Ecole Nationale Supérieure d’Ingénieurs de Tunis, ENSIT Ex ESSTT, Université de Tunis, 5 Avenue Taha Hussein, 1008 Tunis (Tunisia); Li, X. [FEMTO-ST, MN2S, Université de Technologie de Belfort-Montbéliard, Site de Sévenans, 90010 Belfort cedex (France); Khaldi, C., E-mail: chokri.khaldi@esstt.rnu.tn [Equipe des Hydrures Métalliques, Laboratoire de Mécanique, Matériaux et Procédés, Ecole Nationale Supérieure d’Ingénieurs de Tunis, ENSIT Ex ESSTT, Université de Tunis, 5 Avenue Taha Hussein, 1008 Tunis (Tunisia); ElKedim, O. [FEMTO-ST, MN2S, Université de Technologie de Belfort-Montbéliard, Site de Sévenans, 90010 Belfort cedex (France); Lamloumi, J. [Equipe des Hydrures Métalliques, Laboratoire de Mécanique, Matériaux et Procédés, Ecole Nationale Supérieure d’Ingénieurs de Tunis, ENSIT Ex ESSTT, Université de Tunis, 5 Avenue Taha Hussein, 1008 Tunis (Tunisia)

2014-12-05

Highlights: • The Ti{sub 2}Ni alloy activation requires only one cycle of charge and discharge, regardless of the temperature. • By increasing the temperature the capacity loss, undergoes an increase and it is more pronounced for the 60 °C. • A good correlation is found between the evolutions of the different electrochemical parameters according to the temperature. - Abstract: The structure and the electrochemical hydrogen storage properties of amorphous Ti{sub 2}Ni alloy synthesized by ball milling and used as an anode in nickel–metal hydride batteries were studied. Nominal Ti{sub 2}Ni was synthesized under argon atmosphere at room temperature using a planetary high-energy ball mill. The structural and morphological characterization of the amorphous Ti{sub 2}Ni alloy is carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical characterization of the Ti{sub 2}Ni electrodes is carried out by the galvanostatic charging and discharging, the constant potential discharge, the open circuit potential and the potentiodynamic polarization techniques. The Ti{sub 2}Ni alloy activation requires only one cycle of charge and discharge, regardless of the temperature. The electrochemical discharge capacity of the Ti{sub 2}Ni alloy, during the first eight cycles, and at a temperature of 30 °C, remained practically unchanged and a good held cycling is observed. By increasing the temperature, the electrochemical discharge capacity loss after eight cycles undergoes an increase and it is more pronounced for the temperature 60 °C. At 30 °C, the anodic corrosion current density is 1 mA cm{sup −2} and then it undergoes a rapid drop, remaining substantially constant (0.06 mA cm{sup −2}) in the range 40–60 °C, before undergoing a slight increase to 70 °C (0.3 mA cm{sup −2}). This variation is in good agreement with the maximum electrochemical discharge capacity values found for the

Tritium evacuataion performance of a large oil-free reciprocating pump

International Nuclear Information System (INIS)

Hayashi, T.; Yamada, M.; Konishi, S.

1994-01-01

In fusion reactors large dry vacuum and transfer pumps are needed for various applications such as backing and roughing for torus evacuation, gas transfer and processing in the fuel cycle, and facility vacuum for safety systems. There are some commercial use oil-free pumps, however, most of all these pumps have low pumping function for hydrogen gases and also at high discharge pressure. A large oil-free reciprocating pump has been developed for high tritium services at the Tritium Process Laboratory (TPL) in the Japan Atomic Energy Research Institute (JAERI). This pump is mainly composed four-stage compression vertical cylinders, a single acting piston with piston rings made by carbon polyimide composite and two buffer tanks. Each stage in the cylinder has 16 special check valves. The process line is isolated completely to crank-case oil by dynamic metal bellows. Design pumping speed is 54 m 3 /hr for hydrogen gas at 5 Torr of discharge pressures. After cold testing in TPL, this pump was shipped and installed in the Tritium Systems Test Assembly (TSTA) loop of the Los Alamos National Laboratory under the US-Japan Collaboration program on fusion technology

Electrochemical system for the control of oxigen atmospheres in UO2 sintering

International Nuclear Information System (INIS)

Caneiro, Alberto; Abriata, J.P.

1980-01-01

The behaviour of an electrochemical pump and of an oxygen sensor, allowing a precise control of the UO 2 stoichiometry in the preparation and analysis of gaseous mixtures of low oxygen contents is described. The correct functioning of the system can be tested by applying Faraday's law. The oxygen partial pressures can be continuously controlled by the sole varation of the current applied to the electrochemical pump. The partial pressure of the system is within the range between x 10 -1 atm and 10 -27 atm at 800 deg C. This system may be utilized for sintering experiments at a laboratory scale. (M.E.L) [es

Hydrogen-Induced Plastic Deformation in ZnO

Science.gov (United States)

Lukáč, F.; Čížek, J.; Vlček, M.; Procházka, I.; Anwand, W.; Brauer, G.; Traeger, F.; Rogalla, D.; Becker, H.-W.

In the present work hydrothermally grown ZnO single crystals covered with Pd over-layer were electrochemically loaded with hydrogen and the influence of hydrogen on ZnO micro structure was investigated by positron annihilation spectroscopy (PAS). Nuclear reaction analysis (NRA) was employed for determination of depth profile of hydrogen concentration in the sample. NRA measurements confirmed that a substantial amount of hydrogen was introduced into ZnO by electrochemical charging. The bulk hydrogen concentration in ZnO determined by NRA agrees well with the concentration estimated from the transported charge using the Faraday's law. Moreover, a subsurface region with enhanced hydrogen concentration was found in the loaded crystals. Slow positron implantation spectroscopy (SPIS) investigations of hydrogen-loaded crystal revealed enhanced concentration of defects in the subsurface region. This testifies hydrogen-induced plastic deformation of the loaded crystal. Absorbed hydrogen causes a significant lattice expansion. At low hydrogen concentrations this expansion is accommodated by elastic straining, but at higher concentrations hydrogen-induced stress exceeds the yield stress in ZnO and plastic deformation of the loaded crystal takes place. Enhanced hydrogen concentration detected in the subsurface region by NRA is, therefore, due to excess hydrogen trapped at open volume defects introduced by plastic deformation. Moreover, it was found that hydrogen-induced plastic deformation in the subsurface layer leads to typical surface modification: formation of hexagonal shape pyramids on the surface due to hydrogen-induced slip in the [0001] direction.

LH2 three-phase pump control circuit description

International Nuclear Information System (INIS)

Pierce, W.

1977-05-01

A brief description and circuit drawings are given for a pump control system. The pump is used to circulate liquid hydrogen through the cell and heat exchanger of an LH 2 target. The pump is powered by three-phase 60 cycle power, and the control unit is powered from a positive and negative 24 V dc supply available in the NIM Bin. The control unit is packaged in a double-width NIM module. Drawings are given for the pump speed indicator, function generator, and power supply

High-efficiency heat pump technology using metal hydrides (eco-energy city project)

Energy Technology Data Exchange (ETDEWEB)

Morita, Y.; Harada, T.; Niikura, J.; Yamamoto, Y.; Suzuki, J. [Human Environmental Systems Development Center, Matsushita Electric Industrial Co., Ltd., Moriguchi, Osaka (Japan); Gamo, T. [Corporate Environmental Affairs Div., Matsushita Electric Industrial Co., Ltd., Kadoma, Osaka (Japan)

1999-07-01

Metal hybrides are effective materials for utilizing hydrogen as a clean energy medium. That is, when the metal hydrides absorb or desorb the hydrogen, a large heat output of reaction occurs. So, the metal hydrides can be applied to a heat pump. We have researched on a high efficiency heat pump technology using their metal hydrides. In this report, a double effect type metal hydride heat pump configuration is described in which the waste heat of 160 C is recovered in a factory cite and transported to areas far distant from the industrial district. In the heat recovery unit, a low pressure hydrogen is converted into highly effective high pressure hydrogen by applying the metal hydrides. Other metal hydrides perform the parts of heating by absorbing the hydrogen and cooling by desorbing the hydrogen in the heat supply unit. One unit scale of the system is 3 kW class as the sum of heating and cooling. This system using the hydrogen absorbing alloy also has good energy storage characteristics and ambient hydrogen pressure self-safety control ability. Furthermore, this heating and cooling heat supply system is not harmful to the natural environment because it is a chlorofluorocarbon-free, and low noise type system. We have developed in the following element technologies to attain the above purposes, that is development of hydrogen absorbing alloys with high heat outputs and technologies to construct the heat pump system. This study is proceeded at present as one of the programs in New Sunshine Project, which aims for development of ingenious energy utilization technology to achieve reduction of primary energy consumption with keeping cultural and wealthy life and preventing deterioration of global environment. (orig.)

All electrochemical fabrication of a bilayer membrane composed of nanotubular photocatalyst and palladium toward high-purity hydrogen production

Energy Technology Data Exchange (ETDEWEB)

Hattori, Masashi [Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga 816-8580 (Japan); Noda, Kei, E-mail: nodakei@elec.keio.ac.jp [Department of Electronics and Electrical Engineering, Keio University, Hiyoshi, Yokohama 223-8522 (Japan)

2015-12-01

Graphical abstract: - Highlights: • A bilayer membrane composed of TiO{sub 2} nanotube array and palladium was fabricated. • The TiO{sub 2}/Pd bilayer membrane was prepared with an all-electrochemical process. • The membrane consists of pure Pd and anatase TiO{sub 2} nanotubes with no alloy formation. • Photocatalytic H{sub 2} production and concomitant separation were demonstrated. • High-purity H{sub 2} production rate and apparent quantum yield were evaluated. - Abstract: We developed an all-electrochemical technique for fabricating a bilayer structure of a titanium dioxide (TiO{sub 2}) nanotube array (TNA) and a palladium film (TNA/Pd membrane), which works for photocatalytic high-purity hydrogen production. Electroless plating was used for depositing the Pd film on the TNA surface prepared by anodizing a titanium foil. A 3-μm-thick TNA/Pd membrane without any pinholes in a 1.5-cm-diameter area was fabricated by transferring a 1-μm-thick TNA onto an electroless-plated 2-μm-thick Pd film with a mechanical peel-off process. This ultrathin membrane with sufficient mechanical robustness showed photocatalytic H{sub 2} production via methanol reforming under ultraviolet illumination on the TNA side, immediately followed by the purification of the generated H{sub 2} gas through the Pd layer. The hydrogen production rate and the apparent quantum yield for high-purity H{sub 2} production from methanol/water mixture with the TNA/Pd membrane were also examined. This work suggests that palladium electroless plating is more suitable and practical for preparing a well-organized TNA/Pd heterointerface than palladium sputter deposition.

Thermodynamic analysis of the use a chemical heat pump to link a supercritical water-cooled nuclear reactor and a thermochemical water-splitting cycle for hydrogen production

International Nuclear Information System (INIS)

Granovskii, Mikhail; Dincer, Ibrahim; Rosen, Marc A.; Pioro, Igor

2008-01-01

Increases in the power generation efficiency of nuclear power plants (NPPs) are mainly limited by the permissible temperatures in nuclear reactors and the corresponding temperatures and pressures of the coolants in reactors. Coolant parameters are limited by the corrosion rates of materials and nuclear-reactor safety constraints. The advanced construction materials for the next generation of CANDU reactors, which employ supercritical water (SCW) as a coolant and heat carrier, permit improved 'steam' parameters (outlet temperatures up to 625degC and pressures of about 25 MPa). An increase in the temperature of steam allows it to be utilized in thermochemical water splitting cycles to produce hydrogen. These methods are considered by many to be among the most efficient ways to produce hydrogen from water and to have advantages over traditional low-temperature water electrolysis. However, even lower temperature water splitting cycles (Cu-Cl, UT-3, etc.) require an intensive heat supply at temperatures higher than 550-600degC. A sufficient increase in the heat transfer from the nuclear reactor to a thermochemical water splitting cycle, without jeopardizing nuclear reactor safety, might be effectively achieved by application of a heat pump, which increases the temperature of the heat supplied by virtue of a cyclic process driven by mechanical or electrical work. Here, a high-temperature chemical heat pump, which employs the reversible catalytic methane conversion reaction, is proposed. The reaction shift from exothermic to endothermic and back is achieved by a change of the steam concentration in the reaction mixture. This heat pump, coupled with the second steam cycle of a SCW nuclear power generation plant on one side and a thermochemical water splitting cycle on the other, increases the temperature of the 'nuclear' heat and, consequently, the intensity of heat transfer into the water splitting cycle. A comparative preliminary thermodynamic analysis is conducted of

Electrochemical Implications of Defects in Carbon Nanotubes

Science.gov (United States)

Hall, Jonathan Peter

The electrochemical behavior of carbon nanotubes (CNTs) containing both intrinsic and extrinsically introduced defects has been investigated through the study of bamboo and hollow multi-walled CNT morphologies. The controlled addition of argon, hydrogen, and chlorine ions in addition to atomic hydrogen and magnesium vapor was used for varying the charge and type of extrinsic defects. To quantify changes in the CNTs upon treatment, Raman spectroscopy and electrochemical techniques were employed. It was indicated from Raman spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy, and chronopotentiometric experiments that the electrochemical response of hollow type CNTs could be tailored more significantly compared to bamboo type CNTs, which have innately high reactive site densities and are less amenable to modification. Total defect density and edge-plane-like defect concentrations monitored through Raman spectroscopy were used to correlate changes in the electrochemical response of the CNT electrodes as a function of treatment. The implementation of CNT electrodes in a prototypical electrolytic capacitor device was then explored and characterized. Dependencies on source current and redox couple concentration were evaluated, as well as changes in the total capacitance as a function of treatment. Cyclability studies were also performed as a function of source current magnitude to evaluate the longevity of the faradaic currents which typically decrease over time in other similar capacitors. This thesis then concludes with an overall summary of the themes and findings of the research presented in this work.

Measurement of percent hydrogen in the mechanical vacuum pump gas stream during BWR startup

International Nuclear Information System (INIS)

Garcia, Susan E.; Odell, Andrew D.; Giannelli, Joseph F.

2012-09-01

All U.S BWRs use a Mechanical Vacuum Pump (MVP) to establish condenser vacuum during start-ups, normally from the initial heat-up to the point where sufficient reactor steam pressure and flow is available to place the Steam Jet Air Ejector (SJAE) and off-gas treatment system in service. MVP operation is restricted to <5% power and gas stream concentrations of <4% H 2 , the lower flammability limit (LFL) for hydrogen/air mixtures. For a particular plant startup prior to hydrogen injection for hydrogen water chemistry (HWC), the MVP %H 2 would depend on the air in-leakage rate, the H 2 gas generation rate from radiolysis and the gas/steam transport rate from the reactor vessel to the main condenser. The radiolysis rate at low power, which is not precisely known and has not been modeled for the BWR, is normally assumed to increase in proportion to thermal power. Two thirds of the radiolytic gas by volume would be H 2 and one third O 2 . The MVP is not equipped with %H 2 sampling and measurement capability, and many MVP systems include no flow measurement. No U.S plant or literature data on MVP %H 2 were found. The industry-first Early Hydrogen Water Chemistry (EHWC) demonstration at the Peach Bottom 3 nuclear power plant involved hydrogen gas injection into the reactor vessel during startup while the MVP was in service. To support the EHWC project, it was necessary to collect baseline MVP %H 2 data during a startup without hydrogen injection and to monitor MVP %H 2 during the startup with EHWC. The MVP system had no normal sample point, but included test taps in the suction and discharge piping. A sampling method and apparatus was invented (EPRI patent pending), designed, built and applied to obtain %H 2 measurements in the MVP gas stream. The apparatus allowed a gas sample stream to be taken from either the suction (vacuum) or discharge side of the MVP. The gas sample stream was preconditioned to remove moisture (the MVP uses water as a liquid compressant), flowed to

Study of hydrogen isotopes super permeation through vanadium membrane on 'Prometheus' setup

International Nuclear Information System (INIS)

Musyaev, R. K.; Yukhimchuk, A. A.; Lebedev, B. S.; Busnyuk, A. O.; Notkin, M. E.; Samartsev, A. A.; Livshits, A. I.

2008-01-01

To develop the membrane pumping technology by means of superpermeable membranes at RFNC-VNIIEF in the 'Prometheus' setup, the experiments on superpermeation of hydrogen isotopes through metal membranes were carried out. The experimental results on superpermeation of thermal atoms of hydrogen isotopes including tritium through a cylindrical vanadium membrane are presented. The possibility of effective pumping, compression and recuperation of hydrogen isotopes by means of superpermeable membrane was demonstrated. The evaluation of membrane pumping rates and asymmetry degree of pure vanadium membrane was given. The work was performed under the ISTC-2854 project. (authors)

Modeling Results For the ITER Cryogenic Fore Pump. Final Report

Energy Technology Data Exchange (ETDEWEB)

Pfotenhauer, John M. [University of Wisconsin, Madison, WI (United States); Zhang, Dongsheng [University of Wisconsin, Madison, WI (United States)

2014-03-31

A numerical model characterizing the operation of a cryogenic fore-pump (CFP) for ITER has been developed at the University of Wisconsin – Madison during the period from March 15, 2011 through June 30, 2014. The purpose of the ITER-CFP is to separate hydrogen isotopes from helium gas, both making up the exhaust components from the ITER reactor. The model explicitly determines the amount of hydrogen that is captured by the supercritical-helium-cooled pump as a function of the inlet temperature of the supercritical helium, its flow rate, and the inlet conditions of the hydrogen gas flow. Furthermore the model computes the location and amount of hydrogen captured in the pump as a function of time. Throughout the model’s development, and as a calibration check for its results, it has been extensively compared with the measurements of a CFP prototype tested at Oak Ridge National Lab. The results of the model demonstrate that the quantity of captured hydrogen is very sensitive to the inlet temperature of the helium coolant on the outside of the cryopump. Furthermore, the model can be utilized to refine those tests, and suggests methods that could be incorporated in the testing to enhance the usefulness of the measured data.

Sodium removal disassembly and examination of the Fermi secondary sodium pump

International Nuclear Information System (INIS)

Maffei, H.P.; Funk, C.W.; Ballif, J.L.

1974-01-01

The Fermi secondary pump is a centrifugal single stage design. The pump had been operated more than 42,000 hours between 450 and 800 0 F. Sodium was drained from the pump in 1973 and the system was back filled with carbon dioxide. The pump was fabricated for 2.25 Cr-1 Mo Croloy steel. Prior to cleaning the pump was inerted and heated with 150 0 F nitrogen using the pump casing as the containment vessel. The water-vapor-nitrogen process was used in three increasing stages of water concentration. The hydrogen concentration in the discharge line was followed as an indicator of the sodium-water reaction rate. Upon completion of the hydrogen evolution, the pump was rinsed several times with hot water. Six pounds of sodium were removed from the pump during a process cycle of 79 hours including rinsing. The maximum pump temperature recorded was 175 0 F with no variation exceeding 10 0 F. The hydrogen concentration in the effluent provided a very satisfactory index for control of the reaction by adjustment of the water-vapor concentration feed to the system. Rinsing effectiveness was limited by a pool of water in the volute that was not drainable with the available system hook up. Sodium and its compounds were removed from all internal surfaces that could be observed by the first stage of disassembly. All such surfaces were coated with a black deposit. Areas above the sodium liquid level were coated with a vermillion colored oxide. Sodium was found on the (1) threads of the impeller nut lock screw, (2) impeller nut-tapered shaft interface, and (3) vapor deposited sodium was found in the oil seal

Mecanical Properties Degradation by Hydrogen Embrittlement

International Nuclear Information System (INIS)

Bertolino, G; Meyer, G; Perez Ipina J

2001-01-01

The presence of hydrogen-rich media during nuclear plant operation motivates the study of the zirconium alloys degradation of their mechanical properties influenced by hydrogen content and temperature.In this work we study samples with a microstructure of equiaxial grains resulted from hot-rolled, and with different homogeneous hydrogen content obtained by electrochemical charge and a thermal treatment.The influence of hydrogen content and temperature was analyzed from the results of fracture-mechanical tests on CT (compact test) probes using the J-criteria

Enhanced hydrogen storage in sandwich-structured rGO/Co1-xS/rGO hybrid papers through hydrogen spillover

Science.gov (United States)

Han, Lu; Qin, Wei; Jian, Jiahuang; Liu, Jiawei; Wu, Xiaohong; Gao, Peng; Hultman, Benjamin; Wu, Gang

2017-08-01

Reduced graphene oxide (rGO) based two-dimensional (2D) structures have been fabricated for electrochemical hydrogen storage. However, the effective transfer of atomic hydrogen to adjacent rGO surfaces is suppressed by binders, which are widely used in conventional electrochemical hydrogen storage electrodes, leading to a confining of the performance of rGO for hydrogen storage. As a proof of concept experiment, a novel strategy is developed to fabricate the binder-free sandwich-structured rGO/Co1-xS/rGO hybrid paper via facile ball milling and filtration process. Based on the structure investigation, Co1-xS is immobilized in the space between the individual rGO sheets by the creation of chemical "bridges" (Csbnd S bonds). Through the Csbnd S bonds, the atomic hydrogen is transferred from Co1-xS to rGO accompanying a Csbnd H chemical bond formation. When used as an electrode, the hybrid paper exhibits an improved hydrogen storage capacity of 3.82 wt% and, most importantly, significant cycling stability for up to 50 cycles. Excluding the direct hydrogen storage contribution from the Co1-xS in the hybrid paper, the hydrogen storage ability of rGO is enhanced by 10× through the spillover effects caused by the Co1-xS modifier.

High-pressure water electrolysis: Electrochemical mitigation of product gas crossover

International Nuclear Information System (INIS)

Schalenbach, Maximilian; Stolten, Detlef

2015-01-01

Highlights: • New technique to reduce gas crossover during water electrolysis • Increase of the efficiency of pressurized water electrolysis • Prevention of safety hazards due to explosive gas mixtures caused by crossover • Experimental realization for a polymer electrolyte membrane electrolyzer • Discussion of electrochemical crossover mitigation for alkaline water electrolysis - Abstract: Hydrogen produced by water electrolysis can be used as an energy carrier storing electricity generated from renewables. During water electrolysis hydrogen can be evolved under pressure at isothermal conditions, enabling highly efficient compression. However, the permeation of hydrogen through the electrolyte increases with operating pressure and leads to efficiency loss and safety hazards. In this study, we report on an innovative concept, where the hydrogen crossover is electrochemically mitigated by an additional electrode between the anode and the cathode of the electrolysis cell. Experimentally, the technique was applied to a proton exchange membrane water electrolyzer operated at a hydrogen pressure that was fifty times larger than the oxygen pressure. Therewith, the hydrogen crossover was reduced and the current efficiency during partial load operation was increased. The concept is also discussed for water electrolysis that is operated at balanced pressures, where the crossover of hydrogen and oxygen is mitigated using two additional electrodes

Isothermal pumping analysis for high-altitude tethered balloons.

Science.gov (United States)

Kuo, Kirsty A; Hunt, Hugh E M

2015-06-01

High-altitude tethered balloons have potential applications in communications, surveillance, meteorological observations and climate engineering. To maintain balloon buoyancy, power fuel cells and perturb atmospheric conditions, fluids could be pumped from ground level to altitude using the tether as a hose. This paper examines the pumping requirements of such a delivery system. Cases considered include delivery of hydrogen, sulfur dioxide (SO2) and powders as fluid-based slurries. Isothermal analysis is used to determine the variation of pressures and velocities along the pipe length. Results show that transport of small quantities of hydrogen to power fuel cells and maintain balloon buoyancy can be achieved at pressures and temperatures that are tolerable in terms of both the pipe strength and the current state of pumping technologies. To avoid solidification, transport of SO2 would require elevated temperatures that cannot be tolerated by the strength fibres in the pipe. While the use of particle-based slurries rather than SO2 for climate engineering can reduce the pipe size significantly, the pumping pressures are close to the maximum bursting pressure of the pipe.

Synthesis of new copper nanoparticle-decorated anchored type ligands: Applications as non-enzymatic electrochemical sensors for hydrogen peroxide

Energy Technology Data Exchange (ETDEWEB)

Ensafi, Ali A., E-mail: Ensafi@cc.iut.ac.ir; Zandi-Atashbar, N.; Ghiaci, M.; Taghizadeh, M.; Rezaei, B.

2015-02-01

In this work, copper nanoparticles (CuNPs) decorated on two new anchored type ligands were utilized to prepare two electrochemical sensors. These ligands are made from bonding amine chains to silica support including SiO{sub 2}–pro–NH{sub 2} (compound I) and SiO{sub 2}–pro–NH–cyanuric–NH{sub 2} (compound II). The morphology of synthesized CuNPs was characterized by transmission electron microscopy (TEM). The nano-particles were in the range of 13–37 nm with the average size of 23 nm. These materials were used to modify carbon paste electrode. Different electrochemical techniques, including cyclic voltammetry, electrochemical impedance spectroscopy and hydrodynamic chronoamperometry, were used to study the sensor behavior. These electrochemical sensors were used as a model for non-enzymatic detection of hydrogen peroxide (H{sub 2}O{sub 2}). To evaluate the abilities of the modified electrodes for H{sub 2}O{sub 2} detection, the electrochemical signals were compared in the absence and presence of H{sub 2}O{sub 2}. From them, two modified electrodes showed significant responses vs. H{sub 2}O{sub 2} addition. The amperograms illustrated that the sensors were selective for H{sub 2}O{sub 2} sensing with linear ranges of 5.14–1250 μmol L{sup −1} and 1.14–1120 μmol L{sup −1} with detection limits of 0.85 and 0.27 μmol L{sup −1} H{sub 2}O{sub 2}, sensitivities of 3545 and 11,293 μA mmol{sup −1} L and with response times less than 5 s for I/CPE and II/CPE, respectively. As further verification of the selected sensor, H{sub 2}O{sub 2} contained in milk sample was analyzed and the obtained results were comparable with the ones from classical control titration method. - Highlights: • Copper nanoparticles decorating on two new anchored type ligands were prepared. • Ligands are bonding to silica support as SiO{sub 2}–pro–NH{sub 2} and SiO{sub 2}–pro–NH–cyanuric–NH{sub 2}. • These materials were used as electrochemical sensors for H

Pre-treatment technology for electrochemical detection of heavy metal lead and cadmium in food

Directory of Open Access Journals (Sweden)

Ke YAN

2015-04-01

Full Text Available Wet digestion is used as the pre-treatment technology for the electrochemical detection of heavy metals in food, and the complete wet digestion condition of food sample is optimized by electrochemical experiments. The results show that the experimental samples can be digested completely using the Nitric acid-hydrogen peroxide system and is not pre-digested after adding 10 mL nitric acid at 120~140 ℃ and adding 10~15 mL of hydrogen peroxide during the heating process. The correlation coefficient of electrochemical detect is 0.99 for digestion solution of the samples, and the recovery of standard addition is 82%~115%. Wet digestion as a pre-treatment technology of food samples. It can digest sample fully and meet the requirements of electrochemical detection.

Crystal structure of the plasma membrane proton pump

DEFF Research Database (Denmark)

Pedersen, Bjørn P.; Buch-Pedersen, Morten Jeppe; Morth, J. Preben

2007-01-01

A prerequisite for life is the ability to maintain electrochemical imbalances across biomembranes. In all eukaryotes the plasma membrane potential and secondary transport systems are energized by the activity of P-type ATPase membrane proteins: H1-ATPase (the proton pump) in plants and fungi1......-3, and Na1,K1-ATPase (the sodium-potassium pump) in animals4. The name P-type derives from the fact that these proteins exploit a phosphorylated reaction cycle intermediate of ATP hydrolysis5.The plasma membrane proton pumps belong to the type III P-type ATPase subfamily, whereas Na1,K1-ATPase and Ca21......- ATPase are type II6. Electron microscopy has revealed the overall shape of proton pumps7, however, an atomic structure has been lacking. Here we present the first structure of a P-type proton pump determined by X-ray crystallography. Ten transmembrane helices and three cytoplasmic domains define...

One-step and low-temperature synthesis of iodine-doped graphene and its multifunctional applications for hydrogen evolution reaction and electrochemical sensing

International Nuclear Information System (INIS)

Chu, Ke; Wang, Fan; Zhao, Xiao-lin; Wei, Xiao-ping; Wang, Xin-wei; Tian, Ye

2017-01-01

Iodine (I) has emerged as a powerful heteroatom dopant for efficiently tailoring the electrocatalytic properties of graphene. However, the preparation methods of I-doped graphene (I-G) and its electrocatalysis applications remain largely unexplored. Herein, a one-step and low-temperature hydrothermal approach was developed for the successful synthesis of I-G with a high I-doping level (0.52 at.%). The resulting I-G was then applied as a metal-free catalyst for hydrogen evolution reaction (HER) and electrochemical sensing. It was shown that the I-G exhibited a dramatically enhanced HER activity compared to undoped graphene, attributed to the critical role of I-doping in offering large exposed active sites and high electron transfer capability. Furthermore, I-G also displayed attractive sensing performances for highly sensitive and selective detection of dopamine. These findings demonstrate that the hydrothermally synthesized I-G can be a promising electrocatalyst for multifunctional applications in water-splitting and electrochemical sensing.

ENHANCED ELECTROCHEMICAL PROCESSES IN SUBCRITICAL WATER

Energy Technology Data Exchange (ETDEWEB)

Steven B. Hawthorne

2000-07-01

This project involved designing and performing preliminary electrochemical experiments in subcritical water. An electrochemical cell with substantially better performance characteristics than presently available was designed, built, and tested successfully. The electrochemical conductivity of subcritical water increased substantially with temperature, e.g., conductivities increased by a factor of 120 when the temperature was increased from 25 to 250 C. Cyclic voltammograms obtained with platinum and nickel demonstrated that the voltage required to produce hydrogen and oxygen from water can be dropped by a factor of three in subcritical water compared to the voltages required at ambient temperatures. However, no enhancement in the degradation of 1,2-dichlorobenzene and the polychlorinated biphenyl 3,3',4,4'-tetrachlorobiphenyl was observed with applied potential in subcritical water.

Modeling of the symmetry factor of electrochemical proton discharge via the Volmer reaction

DEFF Research Database (Denmark)

Björketun, Mårten E.; Tripkovic, Vladimir; Skúlason, Egill

2013-01-01

A scheme for evaluating symmetry factors of elementary electrode reactions using a density functional theory (DFT) based model of the electrochemical double layer is presented. As an illustration, the symmetry factor is determined for hydrogen adsorption via the electrochemical Volmer reaction...

A Rechargeable Hydrogen Battery.

Science.gov (United States)

Christudas Dargily, Neethu; Thimmappa, Ravikumar; Manzoor Bhat, Zahid; Devendrachari, Mruthunjayachari Chattanahalli; Kottaichamy, Alagar Raja; Gautam, Manu; Shafi, Shahid Pottachola; Thotiyl, Musthafa Ottakam

2018-04-27

We utilize proton-coupled electron transfer in hydrogen storage molecules to unlock a rechargeable battery chemistry based on the cleanest chemical energy carrier molecule, hydrogen. Electrochemical, spectroscopic, and spectroelectrochemical analyses evidence the participation of protons during charge-discharge chemistry and extended cycling. In an era of anthropogenic global climate change and paramount pollution, a battery concept based on a virtually nonpolluting energy carrier molecule demonstrates distinct progress in the sustainable energy landscape.

Menadione metabolism to thiodione in hepatoblastoma by scanning electrochemical microscopy

Science.gov (United States)

Mauzeroll, Janine; Bard, Allen J.; Owhadian, Omeed; Monks, Terrence J.

2004-01-01

The cytotoxicity of menadione on hepatocytes was studied by using the substrate generation/tip collection mode of scanning electrochemical microscopy by exposing the cells to menadione and detecting the menadione-S-glutathione conjugate (thiodione) that is formed during the cellular detoxication process and is exported from the cell by an ATP-dependent pump. This efflux was electrochemically detected and allowed scanning electrochemical microscopy monitoring and imaging of single cells and groups of highly confluent live cells. Based on a constant flux model, ≈6 × 106 molecules of thiodione per cell per second are exported from monolayer cultures of Hep G2 cells. PMID:15601769

Tests of a polarized source of hydrogen and deuterium based on spin-exchange optical pumping and a storage cell for polarized deuterium

International Nuclear Information System (INIS)

Holt, R.J.; Gilman, R.; Kinney, E.R.

1988-01-01

A novel laser-driven polarized source of hydrogen and deuterium which is based on the principle of spin-exchange optical pumping has been developed at Argonne. The advantages of this method over conventional polarized sources for internal target experiments is discussed. At present, the laser-driven polarized source delivers hydrogen 8 x 10 16 atoms/s with a polarization of 24% and deuterium at 6 x 10 16 atoms/s with a polarization of 25%. A passive storage cell for polarized deuterium was tested in the VEPP-3 electron storage ring. The storage cell was found to increase the target thickness by approximately a factor of three and no loss in polarization was observed. 10 refs., 4 figs., 2 tabs

Low-Cost alpha Alane for Hydrogen Storage

Energy Technology Data Exchange (ETDEWEB)

Fabian, Tibor [Ardica Technologies, San Francisco, CA (United States); Petrie, Mark [SRI International, Menlo Park, CA (United States); Crouch-Baker, Steven [SRI International, Menlo Park, CA (United States); Fong, Henry [SRI International, Menlo Park, CA (United States)

2017-10-10

This project was directed towards the further development of the Savannah River National Laboratory (SRNL) lab-scale electrochemical synthesis of the hydrogen storage material alpha-alane and Ardica Technologies-SRI International (SRI) chemical downstream processes that are necessary to meet DoE cost metrics and transition alpha-alane synthesis to an industrial scale. Ardica has demonstrated the use of alpha-alane in a fuel-cell system for the U.S. Army WFC20 20W soldier power system that has successfully passed initial field trials with individual soldiers. While alpha-alane has been clearly identified as a desirable hydrogen storage material, cost-effective means for its production and regeneration on a scale of use applicable to the industry have yet to be established. We focused on three, principal development areas: 1. The construction of a comprehensive engineering techno-economic model to establish the production costs of alpha-alane by both electrochemical and chemical routes at scale. 2. The identification of critical, cost-saving design elements of the electrochemical cell and the quantification of the product yields of the primary electrochemical process. A moving particle-bed reactor design was constructed and operated. 3. The experimental quantification of the product yields of candidate downstream chemical processes necessary to produce alpha-alane to complete the most cost-effective overall manufacturing process. Our techno-economic model shows that under key assumptions most 2015 and 2020 DOE hydrogen storage system cost targets for low and medium power can be achieved using the electrochemical alane synthesis process. To meet the most aggressive 2020 storage system cost target, $1/g, our model indicates that 420 metric tons per year (MT/y) production of alpha-alane is required. Laboratory-scale experimental work demonstrated that the yields of two of the three critical component steps within the overall “electrochemical process” were

Sputtered Pd as hydrogen storage for a chip-integrated microenergy system.

Science.gov (United States)

Slavcheva, E; Ganske, G; Schnakenberg, U

2014-01-01

The work presents a research on preparation and physical and electrochemical characterisation of dc magnetron sputtered Pd films envisaged for application as hydrogen storage in a chip-integrated hydrogen microenergy system. The influence of the changes in the sputtering pressure on the surface structure, morphology, and roughness was analysed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AMF). The electrochemical activity towards hydrogen adsorption/desorption and formation of PdH were investigated in 0.5 M H2SO4 using the methods of cyclic voltammetry and galvanostatic polarisation. The changes in the electrical properties of the films as a function of the sputtering pressure and the level of hydrogenation were evaluated before and immediately after the electrochemical charging tests, using a four-probe technique. The research resulted in establishment of optimal sputter regime, ensuring fully reproducible Pd layers with highly developed surface, moderate porosity, and mechanical stability. Selected samples were integrated as hydrogen storage in a newly developed unitized microenergy system and tested in charging (water electrolysis) and discharging (fuel cell) operative mode at ambient conditions demonstrating a stable recycling performance.

Effect of boron addition on the microstructure and electrochemical performance of La2Mg(Ni0.85Co0.15)9 hydrogen storage alloy

International Nuclear Information System (INIS)

Zhang Yanghuan; Dong Xiaoping; Wang Guoqing; Guo Shihai; Ren Jiangyuan; Wang Xinlin

2006-01-01

In order to improve the electrochemical performances of La-Mg-Ni system (PuNi 3 -type) hydrogen storage alloy, a trace of boron was added in La 2 Mg(Ni 0.85 Co 0.15 ) 9 and rapid quenching techniques were used. La 2 Mg(Ni 0.85 Co 0.15 ) 9 B x (x = 0, 0.05, 0.1, 0.15, 0.2) hydrogen storage alloys were prepared by casting and rapid quenching. The microstructures and electrochemical performances of the as-cast and quenched alloys were determined and measured. The effects of the boron content and the quenching rate on the microstructures and electrochemical performances of the alloys were investigated in detail. The obtained results show that the as-cast and quenched alloys are composed of the (La, Mg)Ni 3 phase (PuNi 3 structure), the LaNi 5 phase and the LaNi 2 phase. A trace of the Ni 2 B phase exists in the as-cast alloys containing boron. The Ni 2 B phase in the alloys containing boron nearly disappears after rapid quenching and the relative amount of each phase in the alloys changes with the variety of the quenching rate. The addition of boron obviously enhances the cycle stability of the as-cast and quenched alloys. The effects of boron content on the capacities of the as-cast and quenched alloys are different. The capacities of the as-cast alloys monotonously decrease with the increase of boron content, whereas the capacities of the as-quenched alloys have a maximum value with the change of boron content. The as-cast and quenched alloys have an excellent activation performance

JV Task-121 Electrochemical Synthesis of Nitrogen Fertilizers

Energy Technology Data Exchange (ETDEWEB)

Junhua Jiang; Ted Aulich

2008-11-30

An electrolytic renewable nitrogen fertilizer process that utilizes wind-generated electricity, N{sub 2} extracted from air, and syngas produced via the gasification of biomass to produce nitrogen fertilizer ammonia was developed at the University of North Dakota Energy & Environmental Research Center. This novel process provides an important way to directly utilize biosyngas generated mainly via the biomass gasification in place of the high-purity hydrogen which is required for Haber Bosch-based production of the fertilizer for the production of the widely used nitrogen fertilizers. Our preliminary economic projection shows that the economic competitiveness of the electrochemical nitrogen fertilizer process strongly depends upon the cost of hydrogen gas and the cost of electricity. It is therefore expected the cost of nitrogen fertilizer production could be considerably decreased owing to the direct use of cost-effective 'hydrogen-equivalent' biosyngas compared to the high-purity hydrogen. The technical feasibility of the electrolytic process has been proven via studying ammonia production using humidified carbon monoxide as the hydrogen-equivalent vs. the high-purity hydrogen. Process optimization efforts have been focused on the development of catalysts for ammonia formation, electrolytic membrane systems, and membrane-electrode assemblies. The status of the electrochemical ammonia process is characterized by a current efficiency of 43% using humidified carbon monoxide as a feedstock to the anode chamber and a current efficiency of 56% using high-purity hydrogen as the anode gas feedstock. Further optimization of the electrolytic process for higher current efficiency and decreased energy consumption is ongoing at the EERC.

Electrochemical studies of redox probes in self-organized lyotropic ...

Indian Academy of Sciences (India)

Administrator

quinone|hydroquinone, methyl viologen and ferrocenemethanol probes in a lyotropic hexagonal columnar phase (H1 phase) using cyclic voltammetry and electrochemical impedance ..... hydrogen bond of hydroquinone during oxidation is.

Experimental study of solar pumped laser for magnesium-hydrogen energy cycle

International Nuclear Information System (INIS)

Yabe, T; Okamoto, Y; Ohkubo, T; Uchida, S; Yoshida, K; Bagheri, B; Funatsu, T; Mabuti, A; Oyama, A; Nakagawa, K; Oishi, T; Daito, K; Nakatsuka, M; Yoshida, M; Motokoshi, S; Sato, Y; Baasandash, C; Nakayama, N; Yanagaidani, K

2008-01-01

24.4 W of laser output has been obtained by sun-pumped, Cr-codoped Nd:yttrium aluminum garnet ceramic. The water-cooled laser rod was pumped with a Fresnel lens focusing the natural sunlight. By using the advantages of the Fresnel lenses, the maximum output for unit area of sunlight was 18.7 W/m 2 . Direct concentrated solar illumination was used to pump a 9mm-diameter, 100mm length rod of Cr:Nd:YAG, which was obtained 9%-14% slope efficiency for the laser output. We have analyzed the Cr:YAG laser medium and found it to be an excellent high-power laser candidate for direct solar-pumping schemes which enhances the laser output about 1.8 times more than Nd:YAG

Effect of annealing treatment on structure and electrochemical performance of quenched MmNi4.2Co0.3Mn0.4Al0.3Mg0.03 hydrogen storage alloy

International Nuclear Information System (INIS)

Zhou Zenglin; Song Yueqing; Cui Shun; Huang Changgeng; Qian Wenlian; Lin Chenguang; Zhang Yongjian; Lin Yulin

2010-01-01

MmNi 4.2 Co 0.3 Mn 0.4 Al 0.3 Mg 0.03 hydrogen storage alloy was prepared by single-roll rapid quenching followed by different annealing treatments for 8 h at 1133 K, 1173 K, 1213 K, and 1253 K, respectively. Alloy structure, phase composition, pressure-composition-temperature (PCT) properties, and electrochemical performance of different annealed alloys have been investigated by X-ray diffraction (XRD), field-emission scanning electron microscope (FESEM), energy dispersion spectrometer (EDS), automatic Sieverts-type apparatus, and electrochemical experiments. Electrochemical experiments indicate that the annealing treatment at 1213 K extends cycle life from 193 cycles to 358 cycles, increases the maximum discharge capacity, and slightly decreases the activation behavior. Alloy structure analyses show that the improvement in cycle life is attributed to the formation of a single CaCu 5 -type structure or the relief of an Mg-containing AlMnNi 2 -type second phase. Pressure composition isotherms results illustrate that both the hydrogen absorption capability and the dehydriding equilibrium pressure go up with increased annealing temperature. For its good performance/cost ratio, the Mg-added low-Co alloy annealed at 1213 K would be a promising substitution for MmNi 4.05 Co 0.45 Mn 0.4 Al 0.3 alloy product.

Hydrogen effects in duplex stainless steel welded joints - electrochemical studies

Science.gov (United States)

Michalska, J.; Łabanowski, J.; Ćwiek, J.

2012-05-01

In this work results on the influence of hydrogen on passivity and corrosion resistance of 2205 duplex stainless steel (DSS) welded joints are described. The results were discussed by taking into account three different areas on the welded joint: weld metal (WM), heat-affected zone (HAZ) and parent metal. The corrosion resistance was qualified with the polarization curves registered in a synthetic sea water. The conclusion is that, hydrogen may seriously deteriorate the passive film stability and corrosion resistance to pitting of 2205 DSS welded joints. The presence of hydrogen in passive films increases corrosion current density and decreases the potential of the film breakdown. It was also found that degree of susceptibility to hydrogen degradation was dependent on the hydrogen charging conditions. WM region has been revealed as the most sensitive to hydrogen action.

Using NEG-pumping near a high density internal target

Energy Technology Data Exchange (ETDEWEB)

Gruber, Alexander; Marton, Johann; Widmann, Eberhard; Zmeskal, Johann [Stefan Meyer Institut fuer Subatomare Physik, OeAW (Germany); Orth, Herbert [GSI, Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany)

2009-07-01

The universal detector PANDA will be constructed at the future high-energy antiproton storage ring HESR at FAIR (Facility for Antiproton and Ion Research, GSI/Darmstadt). It will use antiproton beams (1.5 to 15 GeV/c) for hadron physics in the charmonium region. The Stefan Meyer Institut (SMI) contributes to major parts of the PANDA detector like the hydrogen cluster-jet target and the vacuum system of the antiproton - target interaction zone. To ensure low background, the residual gas load in the interaction zone and in the antiproton beam-pipe has to be minimised. Most of the gas load will come from the high density internal hydrogen target. As the detector will cover almost the full solid angle, the installation of pumps near the interaction zone is impossible. Therefore the use of NEG (non-evaporative-getter) coated beam pipes has been considered as an alternative. Two setups with NEG coated tubes have been installed at SMI as prototypes of the PANDA interaction zone. General parameters of the NEG-film, its outgassing behaviour, the pumping speed and the pumping capacity for hydrogen have been tested. The results of the studies on the PANDA-interaction region are presented.

ELECTROCHEMICAL PROMOTED CATALYSIS: TOWARDS PRACTICAL UTILIZATION

Directory of Open Access Journals (Sweden)

DIMITRIOS TSIPLAKIDES

2008-07-01

Full Text Available Electrochemical promotion (EP of catalysis has already been recognized as “a valuable development in catalytic research” (J. Pritchard, 1990 and as “one of the most remarkable advances in electrochemistry since 1950” (J. O’M. Bockris, 1996. Laboratory studies have clearly elucidated the phenomenology of electrochemical promotion and have proven that EP is a general phenomenon at the interface of catalysis and electrochemistry. The major progress toward practical utilization of EP is surveyed in this paper. The focus is given on the electropromotion of industrial ammonia synthesis catalyst, the bipolar EP and the development of a novel monolithic electropromoted reactor (MEPR in conjunction with the electropromotion of thin sputtered metal films. Future perspectives of electrochemical promotion applications in the field of hydrogen technologies are discussed.

The development of hydrogen storage electrode alloys for nickel hydride batteries

Science.gov (United States)

Hong, Kuochih

The development of hydrogen storage electrode alloys in the 1980s resulted in the birth and growth of the rechargeable nickel hydride (Ni/MH) battery. In this paper we describe briefly a semi-empirical electrochemical/thermodynamic approach to develop/screen a hydrogen storage alloy for electrochemical application. More specifically we will discuss the AB x Ti/Zr-based alloys. Finally, the current state of the Ni/MH batteries including commercial manufacture processes, cell performance and applications is given.

Correlation of electrical and physical properties of photoanode with hydrogen evolution in enzymatic photo-electrochemical cell

Energy Technology Data Exchange (ETDEWEB)

Bae, Sanghyun; Kang, Junwon [Department of Environmental Engineering, Yonsei University, 234 Maeji-ri, Hungub-myun, Wonju, Gangwon-do 220-710 (Korea); Shim, Eunjung [Department of Chemistry, Chungnam National University, 220 Gung-dong, Yuseong-gu, Daejeon 305-764 (Korea); Yoon, Jaekyung; Joo, Hyunku [Fossil Energy and Environment Research Department, Korea Institute of Energy Research, 71-2 Jang-dong, Yuseong-gu, Daejeon 305-343 (Korea)

2008-05-01

In this study, the electrical and physical properties, including the current density, open-circuit voltage, morphology and crystalline structure, of an anodized TiO{sub 2} electrode on a titanium foil are correlated with the hydrogen production rate in an enzymatic photo-electrochemical system. The effect of light intensity at ca. 74 and ca. 146 mW cm{sup -2} on the properties is also examined. Anodizing (20 V; bath temperature 5 C; anodizing time 45 min) and subsequent annealing (350-850 C for 5 h) of the Ti foils in an O{sub 2} atmosphere led to the formation of a tube-shaped, or a compact layered, TiO{sub 2} film on the Ti substrate depending on the annealing temperature. The annealing temperature has a similar effect on the properties of the sample and the hydrogen evolution rate. The generated electrical value, the chronoamperometry (CA), is +13 to -229 and +13 to -247 {mu}A for light intensities of ca. 74 and ca. 146 mW cm{sup -2}, while the corresponding open-circuit voltage (OCV) is in the range of -41 to -687 and -144 to 738 mV, respectively. In the absence of light (dark), the CA is 13-29 {mu}A and the OCV is +258 to -126 mW cm{sup -2}. The trend in the electrical properties for the different samples is well matched with the rate of hydrogen evolution. The samples with higher activities (450, 550, and 650 C) have similar X-ray diffraction (XRD) patterns, which clearly indicates that the samples showing the highest evolution rate are composed of both anatase and rutile, while those showing a lower evolution rate are made of either anatase or rutile. Increasing the intensity of the irradiated light causes a remarkable enhancement in the rate of hydrogen production from 71 to 153 {mu}mol h{sup -1} cm{sup -2}. (author)

Effect of residual stresses on hydrogen permeation in iron

International Nuclear Information System (INIS)

Mouanga, M.; Bercot, P.; Takadoum, J.

2010-01-01

The effect of residual stresses on electrochemical permeation in iron membrane was investigated. Four thermal and mechanical treatments were chosen to obtain different surface states in relation to the residual stresses. Residual stresses were determined by X-ray diffraction (XRD) using the Macherauch and Mueller method. The results were completed by the microhardness measurements. For all iron membranes, compressive residual stresses were obtained. Electrochemical permeation experiments using a Devanathan and Stachurski cell were employed to determine the hydrogen permeation behaviour of the various iron membranes. The latter was charged with hydrogen by galvanostatic cathodic polarization in 0.1 M NaOH at 25 deg. C. The experimental results revealed that hydrogen permeation rate increases with increasing residual stresses introduced in iron membranes.

Noble metal nanoparticle-functionalized ZnO nanoflowers for photocatalytic degradation of RhB dye and electrochemical sensing of hydrogen peroxide

International Nuclear Information System (INIS)

Hussain, Muhammad; Sun, Hongyu; Karim, Shafqat; Nisar, Amjad; Khan, Maaz; Ul Haq, Anwar; Iqbal, Munawar; Ahmad, Mashkoor

2016-01-01

Flower-like hierarchical Zinc oxide nanostructures synthesized by co-precipitation method have been hydrothermally functionalized with 8 nm Au NPs and 15 nm Ag nanoparticles. The photocatalytic and electrochemical performance of these structures are investigated. XPS studies show that the composite exhibits a strong interaction between noble metal nanoparticles (NPs) and Zinc oxide nanoflowers. The PL spectra exhibit UV emission arising due to near band edge transition and show that the reduced PL intensities of Au–ZnO and Ag–ZnO composites are responsible for improved photocatalytic activity arising due to increase in defects. Moreover, the presence of Au NPs on ZnO surface remarkably enhances photocatalytic activity as compared to Ag–ZnO and pure ZnO due to the higher catalytic activity and stability of Au NPs. On the other hand, Ag–ZnO-modified glassy carbon electrode shows good amperometric response to hydrogen peroxide (H_2O_2), with linear range from 1 to 20 µM, and detection limit of 2.5 µM (S/N = 3). The sensor shows high and reproducible sensitivity of 50.8 μA cm"−"2 μM"−"1 with a fast response less than 3 s and good stability as compared to pure ZnO and Au–ZnO-based sensors. All these results show that noble metal NPs-functionalized ZnO base nanocomposites exhibit great prospects for developing efficient non-enzymatic biosensor and environmental remediators.Graphical abstractZnO nanoflowers functionalized with noble metal nanoparticles enhance photocatalytic degradation of RhB dye and electrochemical sensing of hydrogen peroxide.

Noble metal nanoparticle-functionalized ZnO nanoflowers for photocatalytic degradation of RhB dye and electrochemical sensing of hydrogen peroxide

Energy Technology Data Exchange (ETDEWEB)

Hussain, Muhammad [PINSTECH, Nanomaterials Research Group, Physics Division (Pakistan); Sun, Hongyu [Tsinghua University, Laboratory of Advanced Materials and The State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering Beijing, National Center for Electron Microscopy (China); Karim, Shafqat; Nisar, Amjad; Khan, Maaz [PINSTECH, Nanomaterials Research Group, Physics Division (Pakistan); Ul Haq, Anwar [PINSTECH, Non-destructive testing Group (Pakistan); Iqbal, Munawar [University of the Punjab, Centre for High Energy Physics (Pakistan); Ahmad, Mashkoor, E-mail: mashkoorahmad2003@yahoo.com [PINSTECH, Nanomaterials Research Group, Physics Division (Pakistan)

2016-04-15

Flower-like hierarchical Zinc oxide nanostructures synthesized by co-precipitation method have been hydrothermally functionalized with 8 nm Au NPs and 15 nm Ag nanoparticles. The photocatalytic and electrochemical performance of these structures are investigated. XPS studies show that the composite exhibits a strong interaction between noble metal nanoparticles (NPs) and Zinc oxide nanoflowers. The PL spectra exhibit UV emission arising due to near band edge transition and show that the reduced PL intensities of Au–ZnO and Ag–ZnO composites are responsible for improved photocatalytic activity arising due to increase in defects. Moreover, the presence of Au NPs on ZnO surface remarkably enhances photocatalytic activity as compared to Ag–ZnO and pure ZnO due to the higher catalytic activity and stability of Au NPs. On the other hand, Ag–ZnO-modified glassy carbon electrode shows good amperometric response to hydrogen peroxide (H{sub 2}O{sub 2}), with linear range from 1 to 20 µM, and detection limit of 2.5 µM (S/N = 3). The sensor shows high and reproducible sensitivity of 50.8 μA cm{sup −2} μM{sup −1} with a fast response less than 3 s and good stability as compared to pure ZnO and Au–ZnO-based sensors. All these results show that noble metal NPs-functionalized ZnO base nanocomposites exhibit great prospects for developing efficient non-enzymatic biosensor and environmental remediators.Graphical abstractZnO nanoflowers functionalized with noble metal nanoparticles enhance photocatalytic degradation of RhB dye and electrochemical sensing of hydrogen peroxide.

Electrochemical treatment of an oxide material, application to superconductors, and obtained superconductors

International Nuclear Information System (INIS)

Grenier, J.C.; Pouchard, M.; Wattiaux, A.

1991-01-01

The present invention describes the electrochemical treatment of a superconductor oxide so as to modify its stoichiometry. These materials comprise in their anionic lattice oxygenated and hydrogenated species. These treated materials are prepared by an electrochemical process in which the oxide is an electrode in a liquid electrolysis. 3 refs., 3 figs

Single step synthesis of gold-amino acid composite, with the evidence of the catalytic hydrogen atom transfer (HAT) reaction, for the electrochemical recognition of Serotonin

Science.gov (United States)

Choudhary, Meenakshi; Siwal, Samarjeet; Nandi, Debkumar; Mallick, Kaushik

2016-03-01

A composite architecture of amino acid and gold nanoparticles has been synthesized using a generic route of 'in-situ polymerization and composite formation (IPCF)' [1,2]. The formation mechanism of the composite has been supported by a model hydrogen atom (H•≡H++e-) transfer (HAT) type of reaction which belongs to the proton coupled electron transfer (PCET) mechanism. The 'gold-amino acid composite' was used as a catalyst for the electrochemical recognition of Serotonin.

Ultramicrosensors based on transition metal hexacyanoferrates for scanning electrochemical microscopy

Directory of Open Access Journals (Sweden)

Maria A. Komkova

2013-10-01

Full Text Available We report here a way for improving the stability of ultramicroelectrodes (UME based on hexacyanoferrate-modified metals for the detection of hydrogen peroxide. The most stable sensors were obtained by electrochemical deposition of six layers of hexacyanoferrates (HCF, more specifically, an alternating pattern of three layers of Prussian Blue and three layers of Ni–HCF. The microelectrodes modified with mixed layers were continuously monitored in 1 mM hydrogen peroxide and proved to be stable for more than 5 h under these conditions. The mixed layer microelectrodes exhibited a stability which is five times as high as the stability of conventional Prussian Blue-modified UMEs. The sensitivity of the mixed layer sensor was 0.32 A·M−1·cm−2, and the detection limit was 10 µM. The mixed layer-based UMEs were used as sensors in scanning electrochemical microscopy (SECM experiments for imaging of hydrogen peroxide evolution.

Electrochemical Chloride extraction using external electrodes?

DEFF Research Database (Denmark)

Ottosen, Lisbeth M.; Pedersen, Anne Juul

2006-01-01

Electrochemical methods for the removal of chloride from concrete have been developed and the methods are primarily designed for situations where corrosion has started due to an increased chloride concentration in the vicinity of the reinforcement. In these methods the reinforcement is used...... as the cathode. However, some unwanted side effects can occur, including alkali-silica reaction and in some cases hydrogen embrittlement. It is also suggested also to use electrochemical chloride extraction in a preventive way in constructions where chloride induced corrosion is likely to be a problem after...... a period of time, i.e. remove the chlorides before the chloride front reaches the reinforcement. If the chlorides are removed from outer few centimetres from the surface, the chloride will not reach the reinforcement and cause damage. By using the electrochemical chloride removal in this preventive way...

Hydrogen permeation through sol-gel-coated iron during galvanostatic charging

International Nuclear Information System (INIS)

Zakorchemna, I.; Carmona, N.; Zakroczymski, T.

2008-01-01

One-layer sol-gel silica-zirconia and two-layer silica-zirconia and zirconia coatings were deposited on one side of iron membranes by spin-coating, densified in air and annealed up to 800 deg. C in vacuum. Hydrogen permeation through the membranes, coated and uncoated, polarised cathodically under galvanostatic control in 0.1 M NaOH solution was studied using the electrochemical permeation technique. During the initial period, the effect of the sol-gel coatings was insignificant. However, the coatings quite efficiently prevented the iron surface become more active to hydrogen entry during a long-lasting cathodic polarisation. In addition, the electrochemical-corrosion behaviour of the coated iron and the effect of the sol-gel coatings on the effective diffusivity of hydrogen in the coated membranes were studied. On the basis of the polarisation curves and the hydrogen permeation data it was proved that the sol-gel coatings blocked the iron surface for the hydrogen evolution reaction and, consequently, for the hydrogen entry into iron. The effective coating coverage was determined by comparison of the hydrogen fluxes permeating the coated and uncoated membranes. Finally the real concentration of hydrogen beneath the uncoated iron sites and the amount of hydrogen stored in a membrane were evaluated

Effects of hydrogen-charging on the properties of S235JR steel

Science.gov (United States)

Pietkun-Greber, Izabela

2017-10-01

The paper presents the test results of the S235JR steel susceptibility to damage under the influence of hydrogen. The test of mechanical properties was performed on the basis of a static stretch test of non-hydrogenated samples and after cathodic polarization. Electrochemical measurements for the assessment of corrosion resistance of non-hydrogenated and hydrogenated steels were carried out using open circuit potential measurement and registering of potentiodynamic polarization curves in a three-electrode measuring system. Hydrogenation was carried out for between 3 and 24 hours in a solution of 0.1 N sulfuric acid (VI) with the addition of 2 mg/dm 3 of arsenic oxide (III) at an electric current density of 10 mA/cm2. The hydrogen content in the steel before and after saturation with hydrogen was determined using the analyzer. Fracture samples after tensile test were observed using scanning electron microscope. The results of the research showed that as the hydrogen concentration in the examined steel increased (the lengthening of the saturation time), the deterioration of its mechanical and electrochemical properties occurred.

Ultrafine hydrogen storage powders

Science.gov (United States)

Anderson, Iver E.; Ellis, Timothy W.; Pecharsky, Vitalij K.; Ting, Jason; Terpstra, Robert; Bowman, Robert C.; Witham, Charles K.; Fultz, Brent T.; Bugga, Ratnakumar V.

2000-06-13

A method of making hydrogen storage powder resistant to fracture in service involves forming a melt having the appropriate composition for the hydrogen storage material, such, for example, LaNi.sub.5 and other AB.sub.5 type materials and AB.sub.5+x materials, where x is from about -2.5 to about +2.5, including x=0, and the melt is gas atomized under conditions of melt temperature and atomizing gas pressure to form generally spherical powder particles. The hydrogen storage powder exhibits improved chemcial homogeneity as a result of rapid solidfication from the melt and small particle size that is more resistant to microcracking during hydrogen absorption/desorption cycling. A hydrogen storage component, such as an electrode for a battery or electrochemical fuel cell, made from the gas atomized hydrogen storage material is resistant to hydrogen degradation upon hydrogen absorption/desorption that occurs for example, during charging/discharging of a battery. Such hydrogen storage components can be made by consolidating and optionally sintering the gas atomized hydrogen storage powder or alternately by shaping the gas atomized powder and a suitable binder to a desired configuration in a mold or die.

Studies of cryocooler based cryosorption pump with activated carbon panels operating at 11K

International Nuclear Information System (INIS)

Kasthurirengan, S; Behera, Upendra; Gangradey, Ranjana; Udgata, Swarup; Krishnamoorthy, V

2012-01-01

Cryosorption pump is the only solution for pumping helium and hydrogen in fusion reactors. It is chosen because it offers highest pumping speed as well as the only suitable pump for the harsh environments in a tokamak. Towards the development of such cryosorption pumps, the optimal choice of the right activated carbon panels is essential. In order to characterize the performance of the panels with indigenously developed activated carbon, a cryocooler based cryosorption pump with scaled down sizes of panels is experimented. The results are compared with the commercial cryopanel used in a CTI cryosorption (model: Cryotorr 7) pump. The cryopanel is mounted on the cold head of the second stage GM cryocooler which cools the cryopanel down to 11K with first stage reaching about ∼50K. With no heat load, cryopump gives the ultimate vacuum of 2.1E-7 mbar. The pumping speed of different gases such as nitrogen, argon, hydrogen, helium are tested both on indigenous and commercial cryopanel. These studies serve as a bench mark towards the development of better cryopanels to be cooled by liquid helium for use with tokamak.

ALT-I pump limiter results on TEXTOR

International Nuclear Information System (INIS)

Dippel, K.H.; Finken, K.H.; Guthrie, S.E.; Malinowski, M.E.; Pontau, A.E.; Campbell, G.A.; Goebel, D.M.; Conn, R.W.

1985-01-01

The ALT-I pump limiter is used to control hydrogen fluxes from the TEXTOR tokamak. The performance of two different modules, the open fixed geometry (FG) and the closed variable geometry (VG) is discussed. In unpumped scoop limiter operation, the pressure in the ALT-I chamber increases to 3x10 -4 torr(FG) and 2x10 -3 torr(VG). With pumping, the fraction of particles incident on the neutralizer plate that is removed is 25-50%(FG) and 50-80%(VG). These removed particles are estimated to be 2-4(8)%(FG) and 6-13%(VG) of the total plasma outflux (Nsub(e)/tausub(p)). The collection of helium from the plasma using the FG module is approximately half as effective as hydrogen collection. The higher particle removal efficiency for the VG module is attributed to lower neutral backstreaming. (author)

Using NEG-pumping near a high density internal target

International Nuclear Information System (INIS)

Gruber, A.; Marton, J.; Widmann, E.; Zmeskal, J.; Orth, H.

2008-01-01

Full text: The Stefan Meyer Institut (SMI) is part of the international PANDA collaboration. The universal detector will be constructed at the future high-energy antiproton storage ring HESR at FAIR (Facility for Antiproton and Ion Research, GSI/Darmstadt). PANDA will use antiproton beams (1.5 to 15 GeV/c) for hadron physics in the charmonium region. SMI contributes to major parts of the PANDA detector like the hydrogen cluster-jet target and the vacuum system of the antiproton - target interaction zone. To ensure low background, the residual gas load in the interaction zone and in the antiproton beam-pipe has to be minimized. Most of the gas load, of course will come from the high density internal hydrogen target. Since the PANDA detector will cover almost the full solid angle, the installation of pumps near the interaction zone is impossible. Therefore, the use of NEG (non-evaporative-getter) coated beam pipes has been considered as an alternative. Two setups with NEG coated tubes have been installed at SMI as prototypes of the PANDA interaction zone. The outgassing behavior, the pumping speed and the pumping capacity for hydrogen have been tested. The status of the studies of the interaction region will be presented. (author)

Particle balance analysis on carbon sheet pump applied to the GAMMA10 tandem mirror plasmas

International Nuclear Information System (INIS)

Ishimoto, Yuki; Nakashima, Yousuke; Ishinuki, Eiichi; Kobayashi, Shinji; Yoshikawa, Masayuki; Tamano, Teruo; Yatsu, Kiyoshi; Sagara, Akio

2000-01-01

Carbon Sheet Pump (CSP) is expected as a tool for reduction of hydrogen recycling. In this paper, particle balance in the CSP is described. The pumping efficiencies estimated from the time evolution of hydrogen pressures during plasma discharges and those estimated from the thermal desorption experiments have no remarkable difference between the cases of 30degC and 200degC within experimental errors. In cases that CSP is used in actual plasma conditions, we established a method which reduces adsorbed gases on the CSP surface with sustaining a sufficient pumping efficiency by continuously heating CSP. (author)

An evaluation of a hubless inducer and a full flow hydraulic turbine driven inducer boost pump

Science.gov (United States)

Lindley, B. K.; Martinson, A. R.

1971-01-01

The purpose of the study was to compare the performance of several configurations of hubless inducers with a hydrodynamically similar conventional inducer and to demonstrate the performance of a full flow hydraulic turbine driven inducer boost pump using these inducers. A boost pump of this type consists of an inducer connected to a hydraulic turbine with a high speed rotor located in between. All the flow passes through the inducer, rotor, and hydraulic turbine, then into the main pump. The rotor, which is attached to the main pump shaft, provides the input power to drive the hydraulic turbine which, in turn, drives the inducer. The inducer, rotating at a lower speed, develops the necessary head to prevent rotor cavitation. The rotor speed is consistent with present main engine liquid hydrogen pump designs and the overall boost pump head rise is sufficient to provide adequate main pump suction head. This system would have the potential for operating at lower liquid hydrogen tank pressures.

Achievement report on research and development in the Sunshine Project in fiscal 1979. Research hydrogen energy subsystems (Research on hydrogen fueled automobiles); 1979 nendo suiso energy subsystem no kenkyu seika hokokusho. Suiso jidosha system no kenkyu

Energy Technology Data Exchange (ETDEWEB)

NONE

1980-03-01

This paper describes research achievements in fiscal 1979 in research on hydrogen fueled automobiles as a research on hydrogen energy subsystems. The previous fiscal year has researched heat insulation methods to reduce evaporation loss from a hydrogen tank, prototype liquid level meters, prototype feed pumps (especially material selection for sliding parts) and a flow rate control method. Fiscal 1979 performed measurements of temperatures in different parts in the tank to elucidate how the heat makes invasion. Measurements were performed for the pump on suction valve behavior, internal pump compression force, liner temperatures, and leakage amount. The status of operation was identified and a high performance pump for use in very low temperatures was developed successfully. The pump has high delivery pressure, good durability, and capability of fine adjustment in the delivery quantity. This made the direct injection system for hydrogen fuel possible. Injection of hydrogen into an engine was possible by vaporizing liquefied hydrogen and supplying it as a low temperature gas used at 0 to -40 degrees C. The system has high efficiency. Fuel feed control was possible at the same level as in the existing automobiles. The prototype direct injection system can handle stably the load in actual cars. Material for the fuel tank is an important problem in terms of weight, whose solution is urged. (NEDO)

First Principle simulations of electrochemical interfaces - a DFT study

DEFF Research Database (Denmark)

Ahmed, Rizwan

for the whole system to qualify as a proper electrochemical interface. I have also contributed to the model, which accounts for pH in the first principle electrode-electrolyte interface simulations. This is an important step forward, since electrochemical reaction rate and barrier for charge transfer can......In this thesis, I have looked beyond the computational hydrogen electrode (CHE) model, and focused on the first principle simulations which treats the electrode-electrolyte interfaces explicitly. Since obtaining a realistic electrode-electrolyte interface was difficult, I aimed to address various...... challenges regarding first principle electrochemical interface modeling in order to bridge the gap between the model interface used in simulations and real catalyst at operating conditions. Atomic scale insight for the processes and reactions that occur at the electrochemical interface presents a challenge...

Membrane-less hydrogen bromine flow battery

OpenAIRE

Braff, W. A.; Bazant, M. Z.; Buie, C. R.

2014-01-01

In order for the widely discussed benefits of flow batteries for electrochemical energy storage to be applied at large scale, the cost of the electrochemical stack must come down substantially. One promising avenue for reducing stack cost is to increase the system power density while maintaining efficiency, enabling smaller stacks. Here we report on a membrane-less, hydrogen bromine laminar flow battery as a potential high power density solution. The membrane-less design enables power densiti...

Proceedings of the DOE chemical energy storage and hydrogen energy systems contracts review

Energy Technology Data Exchange (ETDEWEB)

1980-02-01

Sessions were held on electrolysis-based hydrogen storage systems, hydrogen production, hydrogen storage systems, hydrogen storage materials, end-use applications and system studies, chemical heat pump/chemical energy storage systems, systems studies and assessment, thermochemical hydrogen production cycles, advanced production concepts, and containment materials. (LHK)

Enhancing electrochemical methods for producing and regenerating alane by using electrochemical catalytic additive

Science.gov (United States)

Zidan, Ragaiy

2017-12-26

A process of using an electrochemical cell to generate aluminum hydride (AlH.sub.3) and other high capacity hydrides is provided. The electrolytic cell uses an electro-catalytic-additive within a polar non-salt containing solvent to solubilize an ionic hydride such as NaAlH.sub.4 or LiAlH.sub.4. The resulting electrochemical process results in the formation of AlH.sub.3 adduct. AlH.sub.3 is obtained from the adduct by heating under vacuum. The AlH.sub.3 can be recovered and used as a source of hydrogen for the automotive industry. The resulting spent aluminum can be regenerated into NaAlH.sub.4 or LiAlH.sub.4 as part of a closed loop process of AlH.sub.3 generation.

Hydrogen embrittlement and galvanic corrosion of titanium alloys

Energy Technology Data Exchange (ETDEWEB)

Soh, Jeong Ryong; Jeong, Y. H.; Choi, B. K.; Baek, J. H.; Hwang, D. Y.; Choi, B. S.; Lee, D. J

2000-06-01

The material properties including the fracture behavior of titanium alloys used as a steam generator tube in SMART can be degraded de to the hydrogen embrittlement and the galvanic corrosion occurring as a result of other materials in contact with titanium alloys in a conducting corrosive environment. In this report the general concepts and trends of hydrogen embrittlement are qualitatively described to adequately understand and expect the fracture behavior from hydrogen within the bulk of materials and under hydrogen containing environments because hydrogen embrittlement may be very complicated process. And the characteristics of galvanic corrosion closely related to hydrogen embrittlement is qualitatively based on wimple electrochemical theory.

Hydrogen embrittlement and galvanic corrosion of titanium alloys

International Nuclear Information System (INIS)

Soh, Jeong Ryong; Jeong, Y. H.; Choi, B. K.; Baek, J. H.; Hwang, D. Y.; Choi, B. S.; Lee, D. J.

2000-06-01

The material properties including the fracture behavior of titanium alloys used as a steam generator tube in SMART can be degraded de to the hydrogen embrittlement and the galvanic corrosion occurring as a result of other materials in contact with titanium alloys in a conducting corrosive environment. In this report the general concepts and trends of hydrogen embrittlement are qualitatively described to adequately understand and expect the fracture behavior from hydrogen within the bulk of materials and under hydrogen containing environments because hydrogen embrittlement may be very complicated process. And the characteristics of galvanic corrosion closely related to hydrogen embrittlement is qualitatively based on wimple electrochemical theory

A technique for measuring hydrogen and water in inert gases and the hydrogen concentration in liquid sodium

International Nuclear Information System (INIS)

Smith, C.A.

1978-04-01

A method is described of measuring the hydrogen and water content of an inert gas. It is based upon the use of an electrochemical oxygen cell and has a high sensitivity at low hydrogen and water levels. The following possible applications of the method are described together with supporting experimental measurements: improving the sensitivity and range of the present PFR secondary circuit hydrogen detection instruments; the measurement of hydrogen diffusion coefficients in steels; the measurement of waterside corrosion rates of boiler steels; on-line monitoring of waterside boiler corrosion. Attention is given to the characteristics of diffusion barriers in relation to the first and last of these. (author)

Oxidative regulation of the Na(+)-K(+) pump in the cardiovascular system.

Science.gov (United States)

Figtree, Gemma A; Keyvan Karimi, Galougahi; Liu, Chia-Chi; Rasmussen, Helge H

2012-12-15

The Na(+)-K(+) pump is an essential heterodimeric membrane protein, which maintains electrochemical gradients for Na(+) and K(+) across cell membranes in all tissues. We have identified glutathionylation, a reversible posttranslational redox modification, of the Na(+)-K(+) pump's β1 subunit as a regulatory mechanism of pump activity. Oxidative inhibition of the Na(+)-K(+) pump by angiotensin II- and β1-adrenergic receptor-coupled signaling via NADPH oxidase activation demonstrates the relevance of this regulatory mechanism in cardiovascular physiology and pathophysiology. This has implications for dysregulation of intracellular Na(+) and Ca(2+) as well as increased oxidative stress in heart failure, myocardial ischemia-reperfusion, and regulation of vascular tone under conditions of elevated oxidative stress. Treatment strategies that are able to reverse this oxidative inhibition of the Na(+)-K(+) pump have the potential for cardiovascular-protective effects. Copyright © 2012 Elsevier Inc. All rights reserved.

In situ synthesis of N and Cu functionalized mesoporous FDU-14 resins and carbons for electrochemical hydrogen storage

Energy Technology Data Exchange (ETDEWEB)

Kong, AiGuo; Wang, WenJuan; Yang, Fan; Ding, HanMing; Shan, YongKui [Department of Chemistry, East China Normal University, ShangHai 200062 (China)

2010-07-15

N and Cu cooperatively functionalized mesoporous resin and carbon materials with bicontinuous cubic structure (FDU-14) were obtained by a novel synthesis method. In this method, block copolymers were used as the templates as well as the precursors for the preparation of these modifying mesoporous materials. The CuC{sub 2}O{sub 4} in the channels of mesoporous FDU-14 resins was gotten by in situ oxidation of the templates in a catalytic redox system containing Cu{sup 2+}, Al{sup 3+}, NO{sub 3}{sup -}, PO{sub 4}{sup 3-}, SO{sub 4}{sup 2-} ions. Simultaneously, the phenol-formaldehyde resin frameworks were in situ functionalized by the amine group resulting from the reduction of NO{sub 3}{sup -}, leading to the formation of N and CuC{sub 2}O{sub 4} modified mesoporous FDU-14 resin materials. Its pyrolysis at the different temperatures resulted in the production of N and Cu cooperatively functionalized mesoporous FDU-14 resin and carbon materials. The structure and composition of these materials were characterized by the X-ray power diffraction, transmission electron microscopy, N{sub 2} adsorption-desorption analysis, X-ray photoelectron spectroscopy, infrared spectroscopy, thermogravimetry analysis, and inductive coupled plasma emission spectroscopy. The electrochemical measurement indicated that N and Cu cooperatively functionalized mesoporous FDU-14 carbon materials possessed the enhanced electrochemical hydrogen storage performance. (author)

Changes on iron electrode surface during hydrogen permeation in borate buffer solution

International Nuclear Information System (INIS)

Modiano, S.; Carreno, J.A.V.; Fugivara, C.S.; Torresi, R.M.; Vivier, V.; Benedetti, A.V.; Mattos, O.R.

2008-01-01

Hydrogen interaction with oxide films grown on iron electrodes at open circuit potential (E oc ) and in the passive region (+0.30 V ECS ) was studied by chronopotentiometry, chronoamperometry and electrochemical impedance spectroscopy techniques. The results were obtained in deaerated 0.3 mol L -1 H 3 BO 3 + 0.075 mol L -1 Na 2 B 4 O 7 (BB, pH 8.4) solution before, during and after hydrogen permeation. The iron oxide film modification was also investigated by means of in situ X-ray absorption near-edge spectroscopy (XANES) and scanning electrochemical microscopy (SECM) before and during hydrogen permeation. The main conclusion was that the passive film is reduced during the hydrogen diffusion. The hydrogen permeation stabilizes the iron surface at a potential close to the thermodynamic water stability line where hydrogen evolution can occur. The stationary condition required for the determination of the permeation parameters cannot be easily attained on iron surface during hydrogen permeation. Moreover, additional attention must be paid when obtaining the transport parameters using the classical permeation cell

Pulse-reverse electrodeposition for mesoporous metal films: combination of hydrogen evolution assisted deposition and electrochemical dealloying.

Science.gov (United States)

Cherevko, Serhiy; Kulyk, Nadiia; Chung, Chan-Hwa

2012-01-21

Hydrogen evolution assisted electrodeposition is a new bottom-up technique allowing the fast and simple synthesis of nanometals. Electrochemical dealloying is a top-down approach with the same purpose. In this work, we show that a combination of these two methods in sequence by pulse-reverse electrodeposition can be used to prepare high-surface-area nanostructured metals. Highly porous adherent platinum is obtained by the deposition of CuPt alloy during the cathodic cycles and the selective dissolution of copper during the anodic cycles. The convection created by the movement of the hydrogen bubbles increases the deposition rate and removes the dissolved copper ions from the diffusion layer, which ensures the deposition of a film with the same stoichiometry throughout the whole process. Due to the relatively high ratio of copper atoms on the surface in the as-deposited layer, it is proposed that the dealloying kinetics is significantly higher than that usually observed during the dealloying process in a model system. The proposed approach has several advantages over other methods, such as a very high growth rate and needlessness of any post-treatment processes. A detailed analysis of the effect of pulse-reverse waveform parameters on the properties of the films is presented. Mesoporous platinum with pores and ligaments having characteristic sizes of less than 10 nm, an equivalent surface area of up to ca. 220 m(2) cm(-3), and a roughness factor of more than 1000 is fabricated.

Electrochemical properties of mixed WC and Pt-black powders

Directory of Open Access Journals (Sweden)

MAJA D. OBRADOVIC

2008-12-01

Full Text Available The electrochemical characteristics of a mixture of Pt-black and WC powders and its catalytic activity for methanol and formic acid oxidation were investigated in acid solution. XRD and AFM measurements revealed that the WC powder employed for the investigation was a single-phase material consisting of crystallites/spherical particles of average size of about 50 nm, which were agglomerated into much larger particles. Cyclic voltammetry showed that the WC underwent electrochemical oxidation, producing tungstate species. In the case of the mixed Pt + WC powders, the tungstate species were deposited on the Pt as a thin film of hydrous tungsten oxide. Enhanced hydrogen intercalation in the hydrous tungsten oxide was observed and it was proposed to be promoted in mixed powders by the presence of hydrogen adatoms on bare Pt sites. The determination of Pt surface area in the Pt + WC layer by stripping of underpotentially deposited Cu revealed that the entire Pt surface was accessible for underpotential deposition of Cu. Investigation of the electrochemical oxidation of methanol and formic acid on Pt + WC and pure Pt layers did not indicate electrocatalytic promotion due to the presence of WC.

Hydrogen in ZnO - a challenge to experiments and theory

Energy Technology Data Exchange (ETDEWEB)

Brauer, Gerhard [Forschungszentrum Dresden-Rossendorf e.V., Dresden (Germany); Kuriplach, Jan [Charles University, Prague (Czech Republic)

2008-07-01

Positron lifetime spectroscopy, nuclear reaction analysis and X-ray diffraction have been combined to investigate various, nominally undoped, ZnO single crystals. Hydrogen is detected in all crystals in a bound state (0.3-0.8 at.-%), and in some cases also in an unbound state (0.7-1.9 at.-%), which can be removed by annealing. A single positron lifetime of 180-182 ps and 165-167 ps is measured for all hydrothermally and melt grown crystals, respectively. These lifetimes are attributed to zinc vacancy-hydrogen complexes, as deduced from ab initio studies of various vacancy-hydrogen defect configurations in ZnO and related positron calculations. In addition, various defect studies of hydrothermally grown (0001) oriented ZnO crystals electrochemically doped with hydrogen are presented. It is demonstrated that a very high amount of hydrogen (up to {proportional_to}30 at.-%) can be introduced into the crystals by electrochemical doping. It is found that more than half of this amount is chemically bound, i.e. incorporated into the ZnO crystal lattice.

Respondence Between Electrochemical Fluctuations and Phenomenon for Localized Corrosion of Less-Noble Metals

International Nuclear Information System (INIS)

Itoi, Yasuhiko; Take, Seisho; Tsuru, Tooru

2008-01-01

We have been studying application of electrochemical noise (Fluctuation) analysis for localized corrosion. Foils of Zinc, Aluminum and Magnesium were used as specimens for electrochemical cell simulating localized corrosion. These specimens were dipped in sodium chloride solutions adjusted to each exponent of hydrogen ion concentration (pH) condition of 5.5, 10, 12 respectively. Time variations of potential and current were measured in those solutions, and simultaneously the surfaces of specimens were observed using microscope with television monitor. Two types of electrochemical cells were arranged for experiments simulated localized corrosion. The fluctuations on trendy component of short-circuited potential and short-circuited current were appeared in synchronization. It was seemed that these fluctuations result from hydrogen evolution on the aluminum active site in the crevice from the microscopic observation. In the case of zinc and magnesium, fluctuations appeared on the trendy component of the corrosion potential. Two types fluctuation were detected. First one is the fluctuation varied periodically. The second one is the random fluctuation. It was seemed that these fluctuations result from generation of corrosion products and hydrogen evolution on the active site in the crevice of zinc and magnesium from the microscopic observation

Anaerobic electrochemical membrane bioreactor and process for wastewater treatment

KAUST Repository

Amy, Gary

2015-07-09

An anaerobic electrochemical membrane bioreactor (AnEMBR) can include a vessel into which wastewater can be introduced, an anode electrode in the vessel suitable for supporting electrochemically active microorganisms (EAB, also can be referred to as anode reducing bacteria, exoelectrogens, or electricigens) that oxidize organic compounds in the wastewater, and a cathode membrane electrode in the vessel, which is configured to pass a treated liquid through the membrane while retaining the electrochemically active microorganisms and the hydrogenotrophic methanogens (for example, the key functional microbial communities, including EAB, methanogens and possible synergistic fermenters) in the vessel. The cathode membrane electrode can be suitable for catalyzing the hydrogen evolution reaction to generate hydro en.

A novel versatile microbiosensor for local hydrogen detection by means of scanning photoelectrochemical microscopy.

Science.gov (United States)

Zhao, Fangyuan; Conzuelo, Felipe; Hartmann, Volker; Li, Huaiguang; Stapf, Stefanie; Nowaczyk, Marc M; Rögner, Matthias; Plumeré, Nicolas; Lubitz, Wolfgang; Schuhmann, Wolfgang

2017-08-15

The development of a versatile microbiosensor for hydrogen detection is reported. Carbon-based microelectrodes were modified with a [NiFe]-hydrogenase embedded in a viologen-modified redox hydrogel for the fabrication of a sensitive hydrogen biosensor By integrating the microbiosensor in a scanning photoelectrochemical microscope, it was capable of serving simultaneously as local light source to initiate photo(bio)electrochemical reactions while acting as sensitive biosensor for the detection of hydrogen. A hydrogen evolution biocatalyst based on photosystem 1-platinum nanoparticle biocomplexes embedded into a specifically designed redox polymer was used as a model for proving the capability of the developed hydrogen biosensor for the detection of hydrogen upon localized illumination. The versatility and sensitivity of the proposed microbiosensor as probe tip allows simplification of the set-up used for the evaluation of complex electrochemical processes and the rapid investigation of local photoelectrocatalytic activity of biocatalysts towards light-induced hydrogen evolution. Copyright © 2017 Elsevier B.V. All rights reserved.

Nickel foam/polyaniline-based carbon/palladium composite electrodes for hydrogen storage

International Nuclear Information System (INIS)

Skowronski, Jan M.; Urbaniak, Jan

2008-01-01

The sandwich-like nickel/palladium/carbon electrodes exhibiting ability to absorb hydrogen in alkaline solution are presented. Electrodes were prepared by successive deposition of palladium and polyaniline layers on nickel foam substrate followed by heat treatment to give Ni/Pd/C electrode. It was shown that thermal conversion of polymer into carbon layer and subsequent thermal activation of carbon component bring about the modification of the mechanism of reversible hydrogen sorption. It was proven that carbon layer, interacting with Pd catalyst, plays a considerable role in the process of hydrogen storage. In the other series of experiments, Pd particles were dispersed electrochemically on carbon coating leading to Ni/C/Pd system. The adding of the next carbon layer resulted in Ni/C/Pd/C electrodes. Electrochemical properties of the electrodes depend on both the sequence of Pd and C layers and the preparation/activation of carbon coating. Electrochemical behavior of sandwich-like electrodes in the reaction of hydrogen sorption/desorption was characterized in 6 M KOH using the cyclic voltammetry method and the results obtained were compared to those for Ni/Pd electrode. The anodic desorption of hydrogen from electrodes free and containing carbon layer was considered after the potentiodynamic as well as potentiostatic sorption of hydrogen. The influence of the sorption potential and the time of rest of electrodes at a cut-off circuit on the kinetics of hydrogen recovery were examined. The results obtained for Ni/Pd/C electrodes indicate that the displacement of hydrogen between C and Pd phase takes place during the rest at a cut-off circuit. Electrodes containing carbon layer require longer time for hydrogen electrosorption. On the other hand, the presence of carbon layer in electrodes is advantageous because a considerable longer retention of hydrogen is possible, as compared to Pd/Ni electrode. Hydrogen stored in sandwich-like electrodes can instantly be

Favoring the unfavored: Selective electrochemical nitrogen fixation using a reticular chemistry approach.

Science.gov (United States)

Lee, Hiang Kwee; Koh, Charlynn Sher Lin; Lee, Yih Hong; Liu, Chong; Phang, In Yee; Han, Xuemei; Tsung, Chia-Kuang; Ling, Xing Yi

2018-03-01

Electrochemical nitrogen-to-ammonia fixation is emerging as a sustainable strategy to tackle the hydrogen- and energy-intensive operations by Haber-Bosch process for ammonia production. However, current electrochemical nitrogen reduction reaction (NRR) progress is impeded by overwhelming competition from the hydrogen evolution reaction (HER) across all traditional NRR catalysts and the requirement for elevated temperature/pressure. We achieve both excellent NRR selectivity (~90%) and a significant boost to Faradic efficiency by 10 percentage points even at ambient operations by coating a superhydrophobic metal-organic framework (MOF) layer over the NRR electrocatalyst. Our reticular chemistry approach exploits MOF's water-repelling and molecular-concentrating effects to overcome HER-imposed bottlenecks, uncovering the unprecedented electrochemical features of NRR critical for future theoretical studies. By favoring the originally unfavored NRR, we envisage our electrocatalytic design as a starting point for high-performance nitrogen-to-ammonia electroconversion directly from water vapor-abundant air to address increasing global demand of ammonia in (bio)chemical and energy industries.

Hanford high level waste (HLW) tank mixer pump safe operating envelope reliability assessment

International Nuclear Information System (INIS)

Fischer, S.R.; Clark, J.

1993-01-01

The US Department of Energy and its contractor, Westinghouse Corp., are responsible for the management and safe storage of waste accumulated from processing defense reactor irradiated fuels for plutonium recovery at the Hanford Site. These wastes, which consist of liquids and precipitated solids, are stored in underground storage tanks pending final disposition. Currently, 23 waste tanks have been placed on a safety watch list because of their potential for generating, storing, and periodically releasing various quantities of hydrogen and other gases. Tank 101-SY in the Hanford SY Tank Farm has been found to release hydrogen concentrations greater than the lower flammable limit (LFL) during periodic gas release events. In the unlikely event that an ignition source is present during a hydrogen release, a hydrogen burn could occur with a potential to release nuclear waste materials. To mitigate the periodic gas releases occurring from Tank 101-SY, a large mixer pump currently is being installed in the tank to promote a sustained release of hydrogen gas to the tank dome space. An extensive safety analysis (SA) effort was undertaken and documented to ensure the safe operation of the mixer pump after it is installed in Tank 101-SY.1 The SA identified a need for detailed operating, alarm, and abort limits to ensure that analyzed safety limits were not exceeded during pump operations

12,000 l/sec cryopump for hydrogen gas

International Nuclear Information System (INIS)

Shibata, Takemasa; Matsuda, Shinzaburo; Shirakata, Hirofumi; Saito, Masaki; Mizuno, Masayasu.

1978-08-01

In the neutral beam injector of JT-60, cryogenic pumps with pumping rate 10 6 l/sec for hydrogen will be installed in the beam lines. To develop the cryopumps a small-scale pump of 12,000 l/sec was made and its fundamental pumping characteristics were measured. The cryogenic pump consists of liquid helium cooled panel, liquid nitrogen cooled chevron and radiation shields. The cryopanel is cylindrical form and the chevron is arranged concentrically within it. The measured pumping rate agrees with the design one. The pumping rate is not lowered by 30 Torr.l/cm 2 on the cryopanel. Liquid helium consumption rate was also measured and the pressure rise in the vacuum chamber in reactivation of the cryopanel was observed. (auth.)

Effect of oxygen implantation on the electrochemical properties of palladium

International Nuclear Information System (INIS)

Fujihana, T.; Ueshima, M.; Takahashi, K.; Iwaki, M.

1995-01-01

Hydrogen presence in metals has significant effects on their properties. A stress caused by hydrogen migration leads to cracks in metals. The suppression of hydrogen incorporation for the protection of such hydrogen embrittlement is one of the most important subjects for industrial engineering. In contrast, the development of active materials for hydrogen absorption and desorption reactions is expected to make a potable storage of hydrogen which is clean and virtually inexhaustible fuel. The electrochemical properties of O + -implanted Pd measured by cyclic voltammetry in a 0.25 mol dm -3 H 2 SO 4 solution were investigated in relation to their composition and structure. Implantation of 16 O + was performed with doses between 10 17 and 10 18 ions cm -2 at 150 keV, and at nearly room temperature. SIMS, ERD combined with RBS, and XRD were used to analyze the composition depth profile and structure of O + -implanted Pd surface layers. The H atoms were accumulated with a gaussian distribution and carbon materials containing the solid solution of PdCx (x = 0.13--0.15) were also formed in the near surface layers during O + -implantation. The distribution of implanted oxygen changed from gaussian to trapezoidal as the dose increased, accompanied by the crystal growth of Pd(OH) 2 , and simultaneously, the amount of accumulated H atoms increased. The voltammetric measurements revealed that with an increase in the dose, the hydrogen absorption was suppressed at the early stage of sweep cycles, and at the final stage, the redox reaction of both hydrogen and Pd was activated. From these results, the authors propose that the carbon materials containing the PdCx formed during O + -implantation suppress the hydrogen absorption, and the metallic Pd like a Pd-black formed by the reduction of Pd(OH) 2 during voltammetric measurements causes the electrochemical activation of O + -implanted Pd

Effect of fluorination treatment on electrochemical properties of M1Ni{sub 3.5}Co{sub 0.6}Mn{sub 0.4}Al{sub 0.5} hydrogen storage alloy

Energy Technology Data Exchange (ETDEWEB)

Huang, Hongxia, E-mail: hhxhunan@yahoo.com.cn [College of Chemistry and Bioengineering, Guilin University of Technology, Guilin (China); Huang, Kelong [College of Chemistry and Chemical Engineering, Central South University (China)

2012-05-15

The influence of surface treatment by solutions of NH{sub 4}F, LiF and LiF containing KBH{sub 4} on the structure and electrochemical properties of the M1Ni{sub 3.5}Co{sub 0.6}Mn{sub 0.4}Al{sub 0.5} hydrogen storage alloy (in which M1 denotes mischmetal) is investigated. The fluorination treatment improves the electrochemical performances of the M1Ni{sub 3.5}Co{sub 0.6}Mn{sub 0.4}Al{sub 0.5} alloy. The maximum discharge capacity (C{sub max}) increases from 314.8 to 325.7 (NH{sub 4}F), 326.5 (LiF) and 316.4 mAh g{sup -1} (LiF+KBH{sub 4}). After 60 cycles, the capacity retention rate increases from 83.5 to 84.8% (NH{sub 4}F), 89.5% (LiF) and 93.9% (LiF+KBH{sub 4}). The results of the linear polarization and anodic polarization reveal that the exchange current density (I{sub 0}) and the limiting current density (I{sub L}) increase after fluorination treatment, indicating an improvement of the kinetics of the hydrogen absorption/desorption. (author)

Measurements of the electrical resistance and the hydrogen depth distribution for Ni 60Nb 20Zr 20 amorphous alloy before and after hydrogen charging

Science.gov (United States)

Nakano, Sumiaki; Ohtsu, Naofumi; Nagata, Shinji; Yamaura, Shin-ichi; Uchinashi, Sakae; Kimura, Hisamichi; Shikama, Tatsuo; Inoue, Akihisa

2005-02-01

A Ni 60Nb 20Zr 20 amorphous alloy was prepared by the single-roller melt-spinning technique. The change in the electrical resistance of the alloy after electrochemical hydrogen charging in 6 N KOH solution was investigated. The change in the hydrogen depth distribution in the alloy was also investigated by elastic recoil detection. As a result, we found that the electrical resistance of the alloy increases with increasing the hydrogen content in the alloy and that a large number of hydrogen atoms are remained in the surface area of the hydrogen-charged alloy.

Relationship Between Equilibrium Hydrogen Pressure and Exchange Current for the Hydrogen Electrode-Reaction at Mmni(3.9-X)Mn(0.4)A1(X)Co(0.7) Alloy Electrodes

NARCIS (Netherlands)

Senoh, H.; Morimoto, K.; Inoue, H.; Iwakura, C.; Notten, P.H.L.

2000-01-01

We present a theoretical relationship between equilibrium hydrogen pressure and exchange current for the hydrogen electrode reaction which considers the degree of hydrogen coverage at the electrode surface. Electrochemical measurements at MmNi3.9–xMn0.4AlxCo0.7 (0 x 0.8) electrodes were performed to

Electrochemical energy engineering: a new frontier of chemical engineering innovation.

Science.gov (United States)

Gu, Shuang; Xu, Bingjun; Yan, Yushan

2014-01-01

One of the grand challenges facing humanity today is a safe, clean, and sustainable energy system where combustion no longer dominates. This review proposes that electrochemical energy conversion could set the foundation for such an energy system. It further suggests that a simple switch from an acid to a base membrane coupled with innovative cell designs may lead to a new era of affordable electrochemical devices, including fuel cells, electrolyzers, solar hydrogen generators, and redox flow batteries, for which recent progress is discussed using the authors' work as examples. It also notes that electrochemical energy engineering will likely become a vibrant subdiscipline of chemical engineering and a fertile ground for chemical engineering innovation. To realize this vision, it is necessary to incorporate fundamental electrochemistry and electrochemical engineering principles into the chemical engineering curriculum.

Laser driven source of spin polarized atomic deuterium and hydrogen

International Nuclear Information System (INIS)

Poelker, M.; Coulter, K.P.; Holt, R.J.

1993-01-01

Optical pumping of potassium atoms in the presence of a high magnetic field followed by spin exchange collisions with deuterium (hydrogen) is shown to yield a high flux of spin polarized atomic deuterium (hydrogen). The performance of the laser driven source has been characterized as a function of deuterium (hydrogen) flow rate, potassium density, pump laser power, and magnetic field. Under appropriate conditions, the authors have observed deuterium atomic polarization as high as 75% at a flow rate 4.2x10 17 atoms/second. Preliminary results suggest that high nuclear polarizations are obtained in the absence of weak field rf transitions as a result of a spin temperature distribution that evolves through frequent H-H (D-D) collisions

Plasma influence on throat conductance of the TEXTOR pump limiter ALT-I

International Nuclear Information System (INIS)

Hardtke, A.; Finken, K.H.; Reiter, D.; Dippel, K.H.; Goebel, D.M.; McGrath, R.T.; Sagara, A.

1989-01-01

On the TEXTOR pump limiter ALT-I conductance measurements for the backstreaming of gas from the pump limiter vessel through the pump limiter entrance have been performed. In these experiments neutral gas has been injected into the pump limiter plenum during a short pulse. The influence of the instreaming plasma results in a reduction of the conductance of the outstreaming gas. For helium the conductance is reduced to about 40% of the molecular conductance when a plasma flux of 0.8 A/cm 2 (T e =T i =11 eV) is streaming into the pump limiter throat. The reduction of the conductance for backstreaming hydrogen and deuterium under the same plasma conditions is smaller; about 70% of the molecular conductance is obtained. This reduction can be explained by an increased recycling of ions which have been produced in the throat back to the neutralizer plate. The experimental results can be reproduced by Monte Carlo neutral transport code calculations if the recycling coefficient is about 0.85 for hydrogen and deuterium and about 0.95 for helium ions. Processes causing these high recycling coefficients are discussed and their influence is estimated. (orig.)

Hydrogen in oxygen-free, phosphorus-doped copper-Charging techniques, hydrogen contents and modelling of hydrogen diffusion and depth profile

International Nuclear Information System (INIS)

Martinsson, Aasa; Sandstroem, Rolf; Lilja, Christina

2013-01-01

In Sweden spent nuclear fuel is planned to be disposed of by encapsulating in cast iron inserts protected by a copper shell. The copper can be exposed to hydrogen released during corrosion processes in the inserts. If the hydrogen is taken up by the copper, it could lead to hydrogen embrittlement. Specimens from oxygen-free copper have been hydrogen charged using two different methods. The purpose was to investigate how hydrogen could be introduced into copper in a controlled way. The thermal charging method resulted in a reduction of the initial hydrogen content. After electrochemical charging of cylindrical specimens, the measured hydrogen content was 2.6 wt. ppm which should compared with 0.6 wt. ppm before charging. The retained hydrogen after two weeks was reduced by nearly 40%. Recently the paper 'Hydrogen depth profile in phosphorus-doped, oxygen-free copper after cathodic charging' (Martinsson and Sandstrom, 2012) has been published. The paper describes experimental results for bulk specimens as well as presenting a model. Almost all the hydrogen is found to be located less than 100 μm from the surface. This model is used to interpret the experimental results on foils in the present report. Since the model is fully based on fundamental equations, it can be used to analyse what happens in new situations. In this report the effect of the charging intensity, the grain size, the critical nucleus size for hydrogen bubble formation as well as the charging time are analysed

Hydrogen in oxygen-free, phosphorus-doped copper - Charging techniques, hydrogen contents and modelling of hydrogen diffusion and depth profile

Energy Technology Data Exchange (ETDEWEB)

Martinsson, Aasa [Swerea KIMAB, Kista (Sweden); Sandstroem, Rolf [Swerea KIMAB, Kista (Sweden); Div. of Materials Science and Engineering, KTH Royal Institute of Technology, Stockholm (Sweden); Lilja, Christina [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)

2013-01-15

In Sweden spent nuclear fuel is planned to be disposed of by encapsulating in cast iron inserts protected by a copper shell. The copper can be exposed to hydrogen released during corrosion processes in the inserts. If the hydrogen is taken up by the copper, it could lead to hydrogen embrittlement. Specimens from oxygen-free copper have been hydrogen charged using two different methods. The purpose was to investigate how hydrogen could be introduced into copper in a controlled way. The thermal charging method resulted in a reduction of the initial hydrogen content. After electrochemical charging of cylindrical specimens, the measured hydrogen content was 2.6 wt. ppm which should compared with 0.6 wt. ppm before charging. The retained hydrogen after two weeks was reduced by nearly 40%. Recently the paper 'Hydrogen depth profile in phosphorus-doped, oxygen-free copper after cathodic charging' (Martinsson and Sandstrom, 2012) has been published. The paper describes experimental results for bulk specimens as well as presenting a model. Almost all the hydrogen is found to be located less than 100 {mu}m from the surface. This model is used to interpret the experimental results on foils in the present report. Since the model is fully based on fundamental equations, it can be used to analyse what happens in new situations. In this report the effect of the charging intensity, the grain size, the critical nucleus size for hydrogen bubble formation as well as the charging time are analysed.

The preliminary studies of HL-1 plasma with pump limiter

International Nuclear Information System (INIS)

Ran, L.B.; Li, G.D.; Sum, S.Q.

1991-01-01

Reduction of the impurity and control of the density are very important task in the present tokamak research. Some experiments showed that the pump limiter is effective to improve impurity and density control. A small-scale pump limiter has been installed on HL-1 tokamak in 1990 and the experiment has been carried out firstly with hydrogen ohmic discharge. In this paper we would present the improvements of the plasma properties as the pump limiter was main limiter and the movable limiter was auxiliary limiter. (author) 3 refs., 8 figs

The effect of hydrogen peroxide on the electrochemical behaviour of Ti-13Nb-13Zr alloy in Hanks' solution

Directory of Open Access Journals (Sweden)

Sérgio Luiz de Assis

2006-12-01

Full Text Available Titanium alloys are largely used for biomedical applications mainly due to their high corrosion resistance resulting from the protective oxide film formed on their surface. The literature, however, has pointed out discrepancies between in vitro tests and in vivo tests. These discrepancies have been ascribed to hydrogen peroxide (H2O2 generated by inflammatory reactions. In this investigation the electrochemical behaviour of a Ti-13Nb-13Zr alloy, which was developed as material for implants, has been evaluated in Hanks' solution, with and without H2O2. The evolution of the electrochemical behavior was monitored by electrochemical impedance spectroscopy (EIS and the results were fitted to an equivalent circuit that simulates an oxide film as a duplex layer structure composed of an inner barrier layer and an outer porous layer. In the solution without H2O2, the oxide film was very stable during the whole test period. On the other hand, in the solution with H2O2, the EIS results varied significantly, indicating a progressive decrease in the barrier layer resistance until 35 days which was followed by the restoration of the barrier layer protective characteristics against corrosion, either due to its growth or to its self-healing after partial consumption of the oxidant agent. The oxide film formed on the Ti alloy samples after 125 days of immersion in Hanks' solution, either with or without H2O2 was analyzed by XPS. The XPS results revealed the presence of TiO and TiO2 on the samples immersed in the two electrolytes, however, Ti2O3 was only found on the samples exposed to the H2O2 containing solution.

Electrochemical attosyringe.

Science.gov (United States)

Laforge, François O; Carpino, James; Rotenberg, Susan A; Mirkin, Michael V

2007-07-17

The ability to manipulate ultrasmall volumes of liquids is essential in such diverse fields as cell biology, microfluidics, capillary chromatography, and nanolithography. In cell biology, it is often necessary to inject material of high molecular weight (e.g., DNA, proteins) into living cells because their membranes are impermeable to such molecules. All techniques currently used for microinjection are plagued by two common problems: the relatively large injector size and volume of injected fluid, and poor control of the amount of injected material. Here we demonstrate the possibility of electrochemical control of the fluid motion that allows one to sample and dispense attoliter-to-picoliter (10(-18) to 10(-12) liter) volumes of either aqueous or nonaqueous solutions. By changing the voltage applied across the liquid/liquid interface, one can produce a sufficient force to draw solution inside a nanopipette and then inject it into an immobilized biological cell. A high success rate was achieved in injections of fluorescent dyes into cultured human breast cells. The injection of femtoliter-range volumes can be monitored by video microscopy, and current/resistance-based approaches can be used to control injections from very small pipettes. Other potential applications of the electrochemical syringe include fluid dispensing in nanolithography and pumping in microfluidic systems.

Asymmetric Functional Conversion of Eubacterial Light-driven Ion Pumps*

Science.gov (United States)

Inoue, Keiichi; Nomura, Yurika; Kandori, Hideki

2016-01-01

In addition to the well-known light-driven outward proton pumps, novel ion-pumping rhodopsins functioning as outward Na+ and inward Cl− pumps have been recently found in eubacteria. They convert light energy into transmembrane electrochemical potential difference, similar to the prototypical archaeal H+ pump bacteriorhodopsin (BR) and Cl− pump halorhodopsin (HR). The H+, Na+, and Cl− pumps possess the conserved respective DTE, NDQ, and NTQ motifs in the helix C, which likely serve as their functional determinants. To verify this hypothesis, we attempted functional interconversion between selected pumps from each category by mutagenesis. Introduction of the proton-pumping motif resulted in successful Na+ → H+ functional conversion. Introduction of the respective characteristic motifs with several additional mutations leads to successful Na+ → Cl− and Cl− → H+ functional conversions, whereas remaining conversions (H+ → Na+, H+ → Cl−, Cl− → Na+) were unsuccessful when mutagenesis of 4–6 residues was used. Phylogenetic analysis suggests that a H+ pump is the common ancestor of all of these rhodopsins, from which Cl− pumps emerged followed by Na+ pumps. We propose that successful functional conversions of these ion pumps are achieved exclusively when mutagenesis reverses the evolutionary amino acid sequence changes. Dependence of the observed functional conversions on the direction of evolution strongly suggests that the essential structural mechanism of an ancestral function is retained even after the gain of a new function during natural evolution, which can be evoked by a few mutations. By contrast, the gain of a new function needs accumulation of multiple mutations, which may not be easily reproduced by limited mutagenesis in vitro. PMID:26929409

Hydrogen evolution at the negative electrode of the all-vanadium redox flow batteries

Science.gov (United States)

Sun, Che-Nan; Delnick, Frank M.; Baggetto, Loïc; Veith, Gabriel M.; Zawodzinski, Thomas A.

2014-02-01

This work demonstrates a quantitative method to determine the hydrogen evolution rate occurring at the negative carbon electrode of the all vanadium redox flow battery (VRFB). Two carbon papers examined by buoyancy measurements yield distinct hydrogen formation rates (0.170 and 0.005 μmol min-1 g-1). The carbon papers have been characterized using electron microscopy, nitrogen gas adsorption, capacitance measurement by electrochemical impedance spectroscopy (EIS), and X-ray photoelectron spectroscopy (XPS). We find that the specific electrochemical surface area (ECSA) of the carbon material has a strong influence on the hydrogen generation rate. This is discussed in light of the use of high surface area material to obtain high reaction rates in the VRFB.

Biomimetic hydrogen production

Energy Technology Data Exchange (ETDEWEB)

Krassen, Henning

2009-05-15

Hydrogenases catalyze the reduction of protons to molecular hydrogen with outstanding efficiency. An electrode surface which is covered with active hydrogenase molecules becomes a promising alternative to platinum for electrochemical hydrogen production. To immobilize the hydrogenase on the electrode, the gold surface was modified by heterobifunctional molecules. A thiol headgroup on one side allowed the binding to the gold surface and the formation of a self-assembled monolayer. The other side of the molecules provided a surface with a high affinity for the hydrogenase CrHydA1 from Chlamydomonas reinhardtii. With methylviologen as a soluble energy carrier, electrons were transferred from carboxy-terminated electrodes to CrHydA1 and conducted to the active site (H-cluster), where they reduce protons to molecular hydrogen. A combined approach of surface-enhanced infrared absorption spectroscopy, gas chromatography, and surface plasmon resonance allowed quantifying the hydrogen production on a molecular level. Hydrogen was produced with a rate of 85 mol H{sub 2} min{sup -1} mol{sup -1}. On a 1'- benzyl-4,4'-bipyridinum (BBP)-terminated surface, the electrons were mediated by the monolayer and no soluble electron carrier was necessary to achieve a comparable hydrogen production rate (approximately 50% of the former system). The hydrogen evolution potential was determined to be -335 mV for the BBP-bound hydrogenase and -290 mV for the hydrogenase which was immobilized on a carboxy-terminated mercaptopropionic acid SAM. Therefore, both systems significantly reduce the hydrogen production overpotential and allow electrochemical hydrogen production at an energy level which is close to the commercially applied platinum electrodes (hydrogen evolution potential of -270 mV). In order to couple hydrogen production and photosynthesis, photosystem I (PS1) from Synechocystis PCC 6803 and membrane-bound hydrogenase (MBH) from Ralstonia eutropha were bound to each other

Conceptual study of the cryocascade for pumping, separation and recycling of ITER torus exhaust

International Nuclear Information System (INIS)

Mack, A.; Perinic, D.

1994-01-01

For pumping, separation and recycling of the ITER plasma exhaust, a pumping system working reliably under ambient and operating conditions of the ITER reactor is required. The pump is exposed to a magnetic field of about 3 T and has to be resistant to radioactive irradiation of 10 9 rad. In the burn and dwell phase, a gas mixture consisting of hydrogen isotopes, helium ash and impurities has to be pumped at the pressure range of 10 -2 - 10 -1 mbar. Within the framework of the European Fusion Technology Programme, the concept of a primary cryopump for use in ITER is being prepared at KfK. The cryocascade concept is planned to include three pump stages. These pump stages, which are connected in series, consist of individual chambers that may be separated from each other by means of cold valves. In the first stage, the impurities of the reactor exhaust gas are frozen out at 20-30 K. Settling of the hydrogen isotopes H/D/T on the 5 K cryosurfaces takes place in the second stage. This stage is made up of two parallel chambers, which can be switched from the pumping to the regeneration mode or vice versa. The helium fraction is bound in the downstream 5 K adsorption stage

Hydrogen Sensors Boost Hybrids; Today's Models Losing Gas?

Science.gov (United States)

2005-01-01

Advanced chemical sensors are used in aeronautic and space applications to provide safety monitoring, emission monitoring, and fire detection. In order to fully do their jobs, these sensors must be able to operate in a range of environments. NASA has developed sensor technologies addressing these needs with the intent of improving safety, optimizing combustion efficiencies, and controlling emissions. On the ground, the chemical sensors were developed by NASA engineers to detect potential hydrogen leaks during Space Shuttle launch operations. The Space Shuttle uses a combination of hydrogen and oxygen as fuel for its main engines. Liquid hydrogen is pumped to the external tank from a storage tank located several hundred feet away. Any hydrogen leak could potentially result in a hydrogen fire, which is invisible to the naked eye. It is important to detect the presence of a hydrogen fire in order to prevent a major accident. In the air, the same hydrogen-leak dangers are present. Stress and temperature changes can cause tiny cracks or holes to form in the tubes that line the Space Shuttle s main engine nozzle. Such defects could allow the hydrogen that is pumped through the nozzle during firing to escape. Responding to the challenges associated with pinpointing hydrogen leaks, NASA endeavored to improve propellant leak-detection capabilities during assembly, pre-launch operations, and flight. The objective was to reduce the operational cost of assembling and maintaining hydrogen delivery systems with automated detection systems. In particular, efforts have been focused on developing an automated hydrogen leak-detection system using multiple, networked hydrogen sensors that are operable in harsh conditions.

Selection of fluids for tritium pumping systems

International Nuclear Information System (INIS)

Chastagner, P.

1984-02-01

The degradation characteristics of three types of vacuum pump fluids, polyphenyl ethers, perfluoropolyethers and hydrocarbon oils were reviewed. Fluid selection proved to be a critical factor in the long-term performance of tritium pumping systems and subsequent tritium recovery operations. Thermal degradation and tritium radiolysis of pump fluids produce contaminants which can damage equipment and interfere with tritium recovery operations. General characteristics of these fluids are as follows: polyphenyl ether has outstanding radiation resistance, is very stable under normal diffusion pump conditions, but breaks down in the presence of oxygen at anticipated operating temperatures. Perfluoropolyether fluids are very stable and do not react chemically with most gases. Thermal and mechanical degradation products are inert, but the radiolysis products are very corrosive. Most of the degradation products of hydrogen oils are volatile and the principal radiolysis product is methane. Our studies show that polyphenyl ethers and hydrocarbon oils are the preferred fluids for use in tritium pumping systems. No corrosive materials are formed and most of the degradation products can be removed with suitable filter systems

Destructive impact of molecular noise on nanoscale electrochemical oscillators

Science.gov (United States)

Cosi, Filippo G.; Krischer, Katharina

2017-06-01

We study the loss of coherence of electrochemical oscillations on meso- and nanosized electrodes with numeric simulations of the electrochemical master equation for a prototypical electrochemical oscillator, the hydrogen peroxide reduction on Pt electrodes in the presence of halides. On nanoelectrodes, the electrode potential changes whenever a stochastic electron-transfer event takes place. Electrochemical reaction rate coefficients depend exponentially on the electrode potential and become thus fluctuating quantities as well. Therefore, also the transition rates between system states become time-dependent which constitutes a fundamental difference to purely chemical nanoscale oscillators. Three implications are demonstrated: (a) oscillations and steady states shift in phase space with decreasing system size, thereby also decreasing considerably the oscillating parameter regions; (b) the minimal number of molecules necessary to support correlated oscillations is more than 10 times as large as for nanoscale chemical oscillators; (c) the relation between correlation time and variance of the period of the oscillations predicted for chemical oscillators in the weak noise limit is only fulfilled in a very restricted parameter range for the electrochemical nano-oscillator.

Hydrogenated amorphous silicon thin film anode for proton conducting batteries

Science.gov (United States)

Meng, Tiejun; Young, Kwo; Beglau, David; Yan, Shuli; Zeng, Peng; Cheng, Mark Ming-Cheng

2016-01-01

Hydrogenated amorphous Si (a-Si:H) thin films deposited by chemical vapor deposition were used as anode in a non-conventional nickel metal hydride battery using a proton-conducting ionic liquid based non-aqueous electrolyte instead of alkaline solution for the first time, which showed a high specific discharge capacity of 1418 mAh g-1 for the 38th cycle and retained 707 mAh g-1 after 500 cycles. A maximum discharge capacity of 3635 mAh g-1 was obtained at a lower discharge rate, 510 mA g-1. This electrochemical discharge capacity is equivalent to about 3.8 hydrogen atoms stored in each silicon atom. Cyclic voltammogram showed an improved stability 300 mV below the hydrogen evolution potential. Both Raman spectroscopy and Fourier transform infrared spectroscopy studies showed no difference to the pre-existing covalent Si-H bond after electrochemical cycling and charging, indicating a non-covalent nature of the Si-H bonding contributing to the reversible hydrogen storage of the current material. Another a-Si:H thin film was prepared by an rf-sputtering deposition followed by an ex-situ hydrogenation, which showed a discharge capacity of 2377 mAh g-1.

Diffusion of hydrogen in iron oxides

International Nuclear Information System (INIS)

Bruzzoni, P.

1993-01-01

The diffusion of hydrogen in transitions metals oxides has been recently studied at room temperature through the permeability electrochemical technique. This work studies thin oxide layers grown in air or in presence of oxidizing atmospheres at temperatures up to 200 deg C. The substrate was pure iron with different superficial treatments. It was observed that these oxides reduce up to three magnitudes orders, the hydrogen stationary flux through membranes of usual thickness in comparison with iron membranes free of oxide. (Author)

Molybdenum carbide-carbon nanocomposites synthesized from a reactive template for electrochemical hydrogen evolution

KAUST Repository

Alhajri, Nawal Saad

2014-01-01

Molybdenum carbide nanocrystals (Mo2C) with sizes ranging from 3 to 20 nm were synthesized within a carbon matrix starting from a mesoporous graphitic carbon nitride (mpg-C3N4) template with confined pores. A molybdenum carbide phase (Mo2C) with a hexagonal structure was formed using a novel synthetic method involving the reaction of a molybdenum precursor with the carbon residue originating from C3N4 under nitrogen at various temperatures. The synthesized nanocomposites were characterized using powder X-ray diffraction (XRD), temperature-programmed reaction with mass spectroscopy (MS), CHN elemental analyses, thermogravimetric analyses (TGA), nitrogen sorption, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The results indicated that the synthesized samples have different surface structures and compositions, which are accordingly expected to exhibit different electrocatalytic activities toward the hydrogen evolution reaction (HER). Electrochemical measurements demonstrated that the sample synthesized at 1323 K exhibited the highest and most stable HER current in acidic media, with an onset potential of -100 mV vs. RHE, among the samples prepared in this study. This result is attributed to the sufficiently small particle size (∼8 nm on average) and accordingly high surface area (308 m2 g-1), with less oxidized surface entrapped within the graphitized carbon matrix. © 2014 the Partner Organisations.

Pulse electrochemical meso/micro/nano ultraprecision machining technology.

Science.gov (United States)

Lee, Jeong Min; Kim, Young Bin; Park, Jeong Woo

2013-11-01

This study demonstrated meso/micro/nano-ultraprecision machining through electrochemical reactions using intermittent DC pulses. The experiment focused on two machining methods: (1) pulse electrochemical polishing (PECP) of stainless steel, and (2) pulse electrochemical nano-patterning (PECNP) on a silicon (Si) surface, using atomic force microscopy (AFM) for fabrication. The dissolution reaction at the stainless steel surface following PECP produced a very clean, smooth workpiece. The advantages of the PECP process included improvements in corrosion resistance, deburring of the sample surface, and removal of hydrogen from the stainless steel surface as verified by time-of-flight secondary-ion mass spectrometry (TOF-SIMS). In PECNP, the electrochemical reaction generated within water molecules produced nanoscale oxide textures on a Si surface. Scanning probe microscopy (SPM) was used to evaluate nanoscale-pattern processing on a Si wafer surface produced by AFM-PECNP For both processes using pulse electrochemical reactions, three-dimensional (3-D) measurements and AFM were used to investigate the changes on the machined surfaces. Preliminary results indicated the potential for advancing surface polishing techniques and localized micro/nano-texturing technology using PECP and PECNP processes.

Potentiometric Titration Method for Quantitative Determination of Hydrogen Peroxide

National Research Council Canada - National Science Library

Bessette, Russell R

2005-01-01

An electrochemical potentiometric titration method that entails titration of a known volume of a catholyte containing an unknown amount of hydrogen peroxide in a titration cell having two electrodes...

Development of composite metallic membranes for hydrogen purification

International Nuclear Information System (INIS)

Gaillard, F.

2003-12-01

Fuel cells are able to convert chemical energy into electric power. There are different types of cells; the best for automotive applications are Proton Exchange Membrane Fuel Cells. But, these systems need hydrogen of high purity. However, fuel reforming generates a mixture of gases, from which hydrogen has to be extracted before supplying the electrochemical cell. The best way for the purification of hydrogen is the membrane separation technology. Palladium is selectively permeable to hydrogen and this is the reason why this metal is largely used for the membrane development. This work deals with the development of hydrogen-selective membranes by deposition of a thin film of palladium onto a porous mechanical support. For this, we have used the electroless plating technique: a palladium salt and a reducing agent are mixed and the deposition takes place onto the catalytic surface of the substrate. After bibliographic investigations, experimental studies have been performed first with a dense metallic substrate in order to better understand the different parameters controlling the deposition. First of all, potentiometric measurements have been carried out to follow the electrochemical reactions in the bath. Then, kinetic measurements of the coating thickness have been recorded to understand the effect of the bath conditions on the yield and the adhesion of the film. Finally, the electroless plating method has been applied to deposit palladium membranes onto porous stainless steel substrates. After optimisation, the resulting membranes were tested for their hydrogen permeation properties. (author)

MOF-derived Cu-Pd/nanoporous carbon composite as an efficient catalyst for hydrogen evolution reaction: A comparison between hydrothermal and electrochemical synthesis

Science.gov (United States)

Mandegarzad, Sakineh; Raoof, Jahan Bakhsh; Hosseini, Sayed Reza; Ojani, Reza

2018-04-01

In this study, a novel catalyst based on Cu-Pd bimetallic nanoparticles supported on nanoporous carbon composite (NPCC) is successfully fabricated through three-step process and used as an electrocatalyst towards hydrogen evolution reaction (HER). At the first step, MOF-199 is synthesized via two distinct strategies; (1) hydrothermal (HT) and (2) electrochemical (EC). Next, the synthesized MOF-199 is used as a template in order to prepare Cu/NPCC by direct carbonization under N2 atmosphere followed by galvanic replacement reaction of Cu metals by PdII ions. All the prepared materials are characterized by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), and nitrogen adsorption/desorption measurements. The effect of synthesis method of MOF-199 on the electrocatalytic activity of the final product towards HER is investigated. The electrochemical measurements indicate that Cu-Pd/NPCC derived from the MOF prepared by EC method (Cu-Pd/NPCC/EC) exhibits an enhanced catalytic activity towards HER in H2SO4 solution than the Cu-Pd/NPCC/HT. This improvement may be attributed to using of supporting electrolyte in the preparation of Cu-Pd/NPCC/EC.

Hydrogen production from biomass by biological systems

International Nuclear Information System (INIS)

Sharifan, H.R.; Qader, S.

2009-01-01

Hydrogen gas is seen as a future energy carrier, not involved in 'greenhouse' gas and its released energy in combustion can be converted to electric power. Biological system with low energy can produce hydrogen compared to electrochemical hydrogen production via solar battery-based water splitting which requires the use of solar batteries with high energy requirements. The biological hydrogen production occurs in microalgae and cyanobacteria by photosynthesis. They consume biochemical energy to produce molecular hydrogen. Hydrogen in some algae is an anaerobic production in the absence of light. In cyanobacteria the hydrogen production simultaneously happens with nitrogen fixation, and also catalyzed by nitrogenase as a side reaction. Hydrogen production by photosynthetic bacteria is mediated by nitrogenase activity, although hydrogenases may be active for both hydrogen production and hydrogen uptake under some conditions. Genetic studies on photosynthetic microorganisms have markedly increased in recent times, relatively few genetic engineering studies have focused on altering the characteristics of these microorganisms, particularly with respect to enhancing the hydrogen-producing capabilities of photosynthetic bacteria and cyanobacteria. (author)

Electrochemical impedance spectroscopy of fully hydrated Nafion membranes at high and low hydrogen partial pressures

International Nuclear Information System (INIS)

Tsampas, M.N.; Brosda, S.; Vayenas, C.G.

2011-01-01

The proton transport mechanism in fully hydrated Nafion 117 membranes was examined via electrochemical impedance spectroscopy (EIS) and steady-state current–potential measurements both in a symmetric H 2 , Pt|Nafion|Pt, H 2 cell and in a H 2 , Pt|Nafion|Pt, air PEM fuel cell with hydrogen partial pressure values, P H 2 , varied between 0.5 kPa and 100 kPa. In agreement with recent studies it is found that for low P H 2 values the steady-state current–potential curves exhibit bistability and regions of positive slope. In these regions the Nyquist plots are found to exhibit negative real part impedance with a large imaginary component, while the Bode plots show a pronounced negative phase shift. These observations are consistent with the mechanism involving two parallel routes of proton conduction in fully hydrated Nafion membranes, one due to proton migration in the aqueous phase, the other due to proton transfer, probably involving tunneling, between adjacent sulfonate groups in narrow pores. The former mechanism dominates at high P H 2 values and the latter dominates in the low P H 2 region where the real part of the impedance is negative.

Composite metal-hydrogen electrodes for metal-hydrogen batteries. Final report, October 1, 1993 - April 15, 1997

International Nuclear Information System (INIS)

Ruckman, M.W.; Strongin, M.; Weismann, H.

1997-04-01

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

Redox Control and Hydrogen Production in Sediment Caps Using Carbon Cloth Electrodes

Science.gov (United States)

Sun, Mei; Yan, Fei; Zhang, Ruiling; Reible, Danny D.; Lowry, Gregory V.; Gregory, Kelvin B.

2010-01-01

Sediment caps that degrade contaminants can improve their ability to contain contaminants relative to sand and sorbent-amended caps, but few methods to enhance contaminant degradation in sediment caps are available. The objective of this study was to determine if, carbon electrodes emplaced within a sediment cap at poised potential could create a redox gradient and provide electron donor for the potential degradation of contaminants. In a simulated sediment cap overlying sediment from the Anacostia River (Washington, DC), electrochemically induced redox gradients were developed within 3 days and maintained over the period of the test (~100 days). Hydrogen and oxygen were produced by water electrolysis at the electrode surfaces and may serve as electron donor and acceptor for contaminant degradation. Electrochemical and geochemical factors that may influence hydrogen production were studied. Hydrogen production displayed zero order kinetics with ~75% coulombic efficiency and rates were proportional to the applied potential between 2.5V to 5V and not greatly affected by pH. Hydrogen production was promoted by increasing ionic strength and in the presence of natural organic matter. Graphite electrode-stimulated degradation of tetrachlorobenzene in a batch reactor was dependent on applied voltage and production of hydrogen to a concentration above the threshold for biological dechlorination. These findings suggest that electrochemical reactive capping can potentially be used to create “reactive” sediments caps capable of promoting chemical or biological transformations of contaminants within the cap. PMID:20879761

Membrane-less hydrogen bromine flow battery

Science.gov (United States)

Braff, William A.; Bazant, Martin Z.; Buie, Cullen R.

2013-08-01

In order for the widely discussed benefits of flow batteries for electrochemical energy storage to be applied at large scale, the cost of the electrochemical stack must come down substantially. One promising avenue for reducing stack cost is to increase the system power density while maintaining efficiency, enabling smaller stacks. Here we report on a membrane-less hydrogen bromine laminar flow battery as a potential high-power density solution. The membrane-less design enables power densities of 0.795 W cm-2 at room temperature and atmospheric pressure, with a round-trip voltage efficiency of 92% at 25% of peak power. Theoretical solutions are also presented to guide the design of future laminar flow batteries. The high-power density achieved by the hydrogen bromine laminar flow battery, along with the potential for rechargeable operation, will translate into smaller, inexpensive systems that could revolutionize the fields of large-scale energy storage and portable power systems.

The electrochemical behavior and surface structure of titanium electrodes modified by ion beams

International Nuclear Information System (INIS)

Huang, G.F.; Xie, Z.; Huang, W.Q.; Yang, S.B.; Zhao, L.H.

2004-01-01

Industrial grade titanium modified by ion implantation and sputtering was used as electrodes. The effect of ion beam modification on the electrochemical behavior and surface structure of electrodes was investigated. Also discussed is the hydrogen evolution process of the electrode in acidic solution. Several ions such as Fe + , C + , W + , Ni + and others, were implanted into the electrode. The electrochemical tests were carried out in 1N H 2 SO 4 solution at 30±1 deg. C. The electrode potential was measured versus a saturate calomel electrode as a function of immersion time. The cathodic polarization curves were measured by the stable potential static method. The surface layer composition and the chemical state of the electrodes were also investigated by Auger electron spectrometer (AES) and X-ray photoelectron spectroscopy (XPS) technique. The results show that: (1) the stability of modified electrodes depends on the active elements introduced by ion implantation and sputtering deposition. (2) The hydrogen evolution activity of industrial grade titanium may be improved greatly by ion beam modification. (3) Ion beam modification changed the composition and the surface state of electrodes over a certain depth range and forms an activity layer having catalytic hydrogen evolution, which inhibited the absorption of hydrogen and formation of titanium hydride. Thus promoted hydrogen evolution and improved the hydrogen evolution catalytic activity in industrial grade titanium

Journal Of The Korean Hydrogen Energy Society 2

International Nuclear Information System (INIS)

2001-11-01

This book deals with studies such as new ball-milled metal hydride electrode for rechargeable batteries by Noh, Haki; Park, Chung Nyeon, hydrogen absorption by laves phase related BCC solid solution alloys by Etsuo Akiba. The hydrogen absorption kinetics in very thin pd film by Cho, Young Sin; Lee, Jong Suk; Kim, Chang Won. The effect of the ceramic precipitates on the hydrogen solubility in pd alloys by Koh, Je Mann; Lee, Kil Hong; Bada, Seung Nam; Noh, Hak, and AC impedance study of the electrochemical behavior of hydrogen, Oxygen gas mixture at nafion, catalyst electrode interface by Song, S. M and Lee, W. M.

Enhanced activity of CaFeMg layered double hydroxides-supported gold nanodendrites for the electrochemical evolution of oxygen and hydrogen in alkaline media

Science.gov (United States)

Havakeshian, Elaheh; Salavati, Hossein; Taei, Masoumeh; Hasheminasab, Fatemeh; Seddighi, Mohadeseh

2018-02-01

In this study, Au was electrodeposited on a support of CaFeMg layered double hydroxide and then, its catalytic activity was investigated for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). Field emission scanning electron microscopy images showed that a uniform porous film of aggregated nano-particles of the LDH has been decorated with Au nanodendrite-like structures (AuNDs@LDH). The results obtained from polarization curves, Tafel plots and electrochemical impedance spectroscopy showed that the AuNDs@LDH exhibits lower overpotential, higher current density, faster kinetics and enhanced stability for both of the OER and HER, in comparison with the single AuNPs and LDH catalysts.

Optimization of hybrid system (wind-solar energy) for pumping water

African Journals Online (AJOL)

DR OKE

Keywords: Renewable energy; pumping water; technical optimization; ... The country already start on a mega-project of solar power production (2000 MW) ...... with a wind turbine in a standalone renewable energy system based on hydrogen.

Hydrogen diffusion in the anode of Ni/MH secondary batteries

Science.gov (United States)

Feng, F.; Northwood, D. O.

Hydrogen diffusion coefficients ( D) were evaluated in a LaNi 4.7Al 0.3 metal hydride electrode as a function of depth of discharge (DoD) using a newly developed electrochemical method which describes more precisely the practical diffusion behavior. It was found that the hydrogen diffusion coefficient in this electrode increases with increasing DoD at ambient temperature, and for this electrode at 50% DoD, the hydrogen diffusion coefficient increases with increase in temperature, and the activation energy for hydrogen diffusion is 37.3 kJ mol -1.

Achievement report on research and development in the Sunshine Project in fiscal 1978. Research on hydrogen energy subsystems (research on hydrogen fueled automobile systems); 1978 nendo suiso energy subsystem no kenkyu seika hokokusho. Suiso jidosha system no kenkyu

Energy Technology Data Exchange (ETDEWEB)

NONE

1979-03-01

This paper describes the result of discussions on hydrogen fueled automobiles in fiscal 1978. Hydrogen fueled automobiles have a difficulty in developing methods for transporting hydrogen, whereas the liquefied hydrogen method and the metal hydride method are being studied in parallel at the present. It is also necessary to solve such basic problems as the method for supplying hydrogen to engines, the injection method, and countermeasures for abnormal combustion. Safety assurance is also important. Very little information is available presently on methods for storing hydrogen inside a car and supplying thereof, which are required for evaluating utilization of liquefied hydrogen to automobiles. Demonstrative surveys and researches are required to acquire basic materials for hydrogen feeding methods in broader meaning including storage and control. Therefore, fiscal 1977 has begun trial fabrication of experimental liquefied hydrogen tanks, and preliminary and experimental researches on types and materials for feed pumps. Fiscal 1978 has moved forward improvements in prototype tank performance (heat insulation method to reduce evaporation loss), trial fabrication of liquid level meters, trial fabrication of feed pumps (especially selection of materials for the sliding parts), and researches on flow rate control methods. Drawings for modification and experiment of the liquefied hydrogen tanks were prepared, and the promising candidates were selected for material combination in pump sliding parts. Durability tests are continuing thereon. Flow rate control was also discussed. (NEDO)

Method of detecting defects in ion exchange membranes of electrochemical cells by chemochromic sensors

Science.gov (United States)

Brooker, Robert Paul; Mohajeri, Nahid

2016-01-05

A method of detecting defects in membranes such as ion exchange membranes of electrochemical cells. The electrochemical cell includes an assembly having an anode side and a cathode side with the ion exchange membrane in between. In a configuration step a chemochromic sensor is placed above the cathode and flow isolation hardware lateral to the ion exchange membrane which prevents a flow of hydrogen (H.sub.2) between the cathode and anode side. The anode side is exposed to a first reactant fluid including hydrogen. The chemochromic sensor is examined after the exposing for a color change. A color change evidences the ion exchange membrane has at least one defect that permits H.sub.2 transmission therethrough.

An Enzyme Switch Employing Direct Electrochemical Communication between Horseradish Peroxidase and a Poly(aniline) Film.

Science.gov (United States)

Bartlett, P N; Birkin, P R; Wang, J H; Palmisano, F; De Benedetto, G

1998-09-01

An enzyme switch, or microelectrochemical enzyme transistor, responsive to hydrogen peroxide was made by connecting two carbon band electrodes (∼10 μm wide, 4.5 mm long separated by a 20-μm gap) with an anodically grown film of poly(aniline). Horseradish peroxidase (EC 1.11.1.7) was either adsorbed onto the poly(aniline) film or immobilized in an insulating poly(1,2-diaminobenzene) polymer grown electrochemically on top of the poly(aniline) film to complete the device. In the completed device, the conductivity of the poly(aniline) film changes from conducting (between - 0.05 and + 0.3 V vs SCE at pH 5) to insulating (>+0.3 V vs SCE at pH 5) on addition of hydrogen peroxide. The change in conductivity is brought about by oxidation of the poly(aniline) film by direct electrochemical communication between the enzyme and the conducting polymer. This was confirmed by measuring the potential of the poly(aniline) film during switching of the conductivity in the presence of hydrogen peroxide. The devices can be reused by rereducing the poly(aniline) electrochemically to a potential below +0.3 V vs SCE. A blind test showed that the device can be used to determine unknown concentrations of H(2)O(2) in solution and that, when used with hydrogen peroxide concentrations below 0.5 mmol dm(-)(3), the same device maybe reused several times. The possible development of devices of this type for use in applications requiring the measurement of low levels of hydrogen peroxide or horseradish peroxidase is discussed.

Structural analysis and evaluation of a mixer pump in a double-shell tank at the Hanford Site

International Nuclear Information System (INIS)

Rezvani, M.A.; Strehlow, J.P.; Baliga, R.

1993-01-01

The double-shell waste tank 241-SY-101 is a 1,000,000 gallon tank used to store radioactive waste at the Hanford Site near Richland, Washington. With time the waste has formed two layers of sludge, a convective and a nonconvective layer. In addition, a crust has formed over the surface of the waste, isolating the convective layer from the vapor space. Ongoing reactions in the waste cause a buildup of hydrogen molecules that become trapped within the nonconvective layer and under the crust. Over time, this hydrogen buildup increases pressure on the crust from beneath. Every 100 to 140 days, the pressure is released when the crust lifts upward in what is called a waste rollover. To prevent the release of a large volume of hydrogen to the vapor space, a mixer pump has been designed to be installed in the tank to circulate the waste and reduce or prevent the hydrogen buildup. The structural analysis and evaluation designed as part of the hydrogen mitigation test process and presented herein addresses the response of the mixer pump and the tank dome resulting from expected operational and design loads. The loads include deadweight, waste rollover, asymmetric thrust, and pump vibration, as well as seismic loads. The seismically induced loads take into consideration both the convective and the impulsive effects of the waste-filled tank. The structural evaluations were performed in accordance with applicable national codes and standards. The qualification of the mixer pump required the design of a unique mounting assembly to transfer the loads from the pump to the surrounding soil without overstressing the structural components such as the dome penetration riser. Also, special consideration was given to minimize the additional stresses in the already stressed concrete tank dome

Electrochemical reduction of metal ions in dilute solution using hydrogen

NARCIS (Netherlands)

Portegies Zwart, I.; Wijnbelt, E.C.W.; Janssen, L.J.J.

1995-01-01

Reduction of metal ions in dilute solutions is of great interest for purification of waste waters and process liquids. A new electrochemical cell has been introduced. This cell - a GBC-cell - is a combination of a gasdiffusion electrode in direct contact with a packed bed of carbon particles.

Fractional surface termination of diamond by electrochemical oxidation.

Science.gov (United States)

Hoffmann, René; Obloh, Harald; Tokuda, Norio; Yang, Nianjun; Nebel, Christoph E

2012-01-10

The crystalline form of sp(3)-hybridized carbon, diamond, offers various electrolyte-stable surface terminations. The H-termination-selective attachment of nitrophenyl diazonium, imaged by AFM, shows that electrochemical oxidation can control the fractional hydrogen/oxygen surface termination of diamond on the nanometer scale. This is of particular interest for all applications relying on interfacial electrochemistry, especially for biointerfaces.

Electrochemical heterogeneity and corrosion resistance of a welded titanium-zirconium joint

International Nuclear Information System (INIS)

Polyakov, S.G.; Goncharov, A.B.; Onoprienko, L.M.; Smiyan, O.D.

1992-01-01

The electrochemical behavior and corrosion resistance of various welded joints of zirconium alloy N-2.5 with commercial titanium VT1 made by the argon-arc method are studied. Electrochemical heterogeneity is studied by measuring the distribution of potentials over the surface, galvanic currents, and recording of polarization curves for different zones of a welded joint in 5% sulfuric acid solution at 340 K. It is established that electrochemical heterogeneity of the zones of an N-2.5 + VT1 welded joint leads to acceleration of the cathodic process in a welded joint and the anodic process along the fusion line from the titanium direction where the greatest hydrogenation of the metal and corrosion damage is correspondingly observed

Electrochemical sensing platforms based on the different carbon derivative incorporated interface.

Science.gov (United States)

Dervisevic, Muamer; Çevik, Emre; Durmuş, Zehra; Şenel, Mehmet

2016-01-01

their effects on the properties of these biosensors. Biosensors were prepared by Horseradish peroxidase (HRP) immobilization on the composite electrodes composed of carbon black, carbon nanofiber (CNF), extended graphite, multiwalled carbon nanotube (MWCNT), reduced graphene oxide (REGO) and poly(glycidyl methacrylateco-vinylferrocene) (P(GMA-co-VFc)) as mediator, covalent linker, and host matrix for carbon derivatives. The modified pencil graphite electrode (PGE) was used for the detection of hydrogen peroxide and to follow electrochemical behavior of different carbon derivatives which were recorded. The electrochemical characterization was investigated by cyclic voltammetry and electrochemical impedance spectroscopy methods. Amperometric measurements showed that the REGO and MWCNT modified electrodes have excellent performance in comparison with other carbon derivatives studied.

Cryopumping of deuterium hydrogen and helium mixtures on smooth 4.2 K surfaces

International Nuclear Information System (INIS)

Chou, T.S.; Halama, H.J.

1977-01-01

The large quantities of deuterium and hydrogen to be pumped in a fusion reactor and its subsystems favor cryopumping over other pumping methods. Cryogen consumption and the operating pressure will not only depend on the gas to be pumped, but also on the amount of helium gas present in the system. In fact, residual helium pressure between pulses will determine the power dissipation of the pump, and hence, influence the choice of cryocondensation or cryosorption. In this paper we will present the results of our studies on (1) cryotrapping of helium in thick D 2 and H 2 films and hydrogen in D 2 films at 4.2 K; (2) diffusion of He and H 2 from D 2 films; (3) steady-state liquid helium consumption; (4) liquid helium consumption as a function of D 2 and H 2 fluxes being pumped; (5) liquid helium consumption as a function of He partial pressure in the system. Finally, these measurements will suggest maximum permissible He to D 2 and He to H 2 ratios in a cryocondensation pump

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

Hydrogen fuel cells for cars and buses

NARCIS (Netherlands)

Janssen, L.J.J.

2007-01-01

The use of hydrogen fuel cells for cars is strongly promoted by the governments of many countries and by international organizations like the European Community. The electrochem. behavior of the most promising fuel cell (polymer electrolyte membrane fuel cell, PEMFC) is critically discussed, based

Analysis and optimization of a tubular SOFC, using nuclear hydrogen as fuel

Energy Technology Data Exchange (ETDEWEB)

Rodriguez, Daniel G.; Parra, Lazaro R.G.; Fernandez, Carlos R.G., E-mail: dgr@instec.cu [Instituto Superior de Tecnologias y Ciencias Aplicadas, Habana (Cuba). Dept. de Ingenieria Nuclear; Lira, Carlos A.B.O., E-mail: cabol@ufpe.br [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear

2013-07-01

One of the main areas of hydrogen uses as an energy carrier is in fuel cells of high standards as solid oxide fuel cells (SOFC). The SOFCs are fuel cells operate at high temperatures making them ideal for use in large power systems, suitable for distributed generation of electricity. Optimization and analysis of these electrochemical devices is an area of great current study. The computational fluid dynamics software (CFD) have unique advantages for analyzing the influence of design parameters on the efficiency of fuel cells. This paper presents a SOFC design cell which employ as fuel hydrogen produced by thermochemical water splitting cycle (I-S). There will be done the optimization of the main parameters thermodynamic and electrochemical cell operating to achieve top performance. Also will be estimate the cell efficiency and a production-consumption hydrogen system. (author)

Analysis and optimization of a tubular SOFC, using nuclear hydrogen as fuel

International Nuclear Information System (INIS)

Rodriguez, Daniel G.; Parra, Lazaro R.G.; Fernandez, Carlos R.G.; Lira, Carlos A.B.O.

2013-01-01

One of the main areas of hydrogen uses as an energy carrier is in fuel cells of high standards as solid oxide fuel cells (SOFC). The SOFCs are fuel cells operate at high temperatures making them ideal for use in large power systems, suitable for distributed generation of electricity. Optimization and analysis of these electrochemical devices is an area of great current study. The computational fluid dynamics software (CFD) have unique advantages for analyzing the influence of design parameters on the efficiency of fuel cells. This paper presents a SOFC design cell which employ as fuel hydrogen produced by thermochemical water splitting cycle (I-S). There will be done the optimization of the main parameters thermodynamic and electrochemical cell operating to achieve top performance. Also will be estimate the cell efficiency and a production-consumption hydrogen system. (author)

Hydrogen storage performances of LaMg{sub 11}Ni + x wt% Ni (x = 100, 200) alloys prepared by mechanical milling

Energy Technology Data Exchange (ETDEWEB)

Zhang, Yanghuan, E-mail: zhangyh59@sina.com [Key Laboratory of Integrated Exploitation of Baiyun Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010 (China); Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081 (China); Wang, Haitao [Key Laboratory of Integrated Exploitation of Baiyun Obo Multi-Metal Resources, Inner Mongolia University of Science and Technology, Baotou 014010 (China); Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081 (China); Zhai, Tingting; Yang, Tai; Yuan, Zeming; Zhao, Dongliang [Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081 (China)

2015-10-05

Highlights: • Amorphous and nanostructured alloys were prepared by mechanical milling. • The maximum discharge capacity of ball milled alloys reaches to 1053.5 mA h/g. • The addition of Ni significantly increases the discharge capacity. • Increasing milling time reduces the kinetic performances of ball milled alloys. - Abstract: In order to improve the hydrogen storage performances of Mg-based materials, LaMg{sub 11}Ni alloy was prepared by vacuum induction melting. Then the nanocrystalline/amorphous LaMg{sub 11}Ni + x wt% Ni (x = 100, 200) hydrogen storage alloys were synthesized by ball milling technology. The structure characterizations of the alloys were carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical hydrogen storage characteristics were tested by using programmed control battery testing system. The electrochemical impedance spectra (EIS), potentiodynamic polarization curves and potential-step curves were also plotted by an electrochemical workstation (PARSTAT 2273). The results indicate that the as-milled alloys exhibit a nanocrystalline and amorphous structure, and the amorphization degree of the alloys visibly increases with extending milling time. Prolonging the milling duration markedly enhances the electrochemical discharge capacity and cyclic stability of the alloys. The electrochemical kinetics, including high rate discharge ability (HRD), charge transfer rate, limiting current density (I{sub L}), hydrogen diffusion coefficient (D), monotonously decrease with milling time prolonging.

Electrochemical Approach for Effective Antifouling and Antimicrobial Surfaces.

Science.gov (United States)

Gaw, Sheng Long; Sarkar, Sujoy; Nir, Sivan; Schnell, Yafit; Mandler, Daniel; Xu, Zhichuan J; Lee, Pooi See; Reches, Meital

2017-08-09

Biofouling, the adsorption of organisms to a surface, is a major problem today in many areas of our lives. This includes: (i) health, as biofouling on medical device leads to hospital-acquired infections, (ii) water, since the accumulation of organisms on membranes and pipes in desalination systems harms the function of the system, and (iii) energy, due to the heavy load of the organic layer that accumulates on marine vessels and causes a larger consumption of fuel. This paper presents an effective electrochemical approach for generating antifouling and antimicrobial surfaces. Distinct from previously reported antifouling or antimicrobial electrochemical studies, we demonstrate the formation of a hydrogen gas bubble layer through the application of a low-voltage square-waveform pulses to the conductive surface. This electrochemically generated gas bubble layer serves as a separation barrier between the surroundings and the target surface where the adhesion of bacteria can be deterred. Our results indicate that this barrier could effectively reduce the adsorption of bacteria to the surface by 99.5%. We propose that the antimicrobial mechanism correlates with the fundamental of hydrogen evolution reaction (HER). HER leads to an arid environment that does not allow the existence of live bacteria. In addition, we show that this drought condition kills the preadhered bacteria on the surface due to water stress. This work serves as the basis for the exploration of future self-sustainable antifouling techniques such as incorporating it with photocatalytic and photoelectrochemical reactions.

Phase structure and electrochemical properties of La0.67Mg0.33Ni3.0-xCox (x=0.0, 0.25, 0.5, 0.75) hydrogen storage alloys

International Nuclear Information System (INIS)

Wang Dahui; Luo Yongchun; Yan Ruxu; Zhang Faliang; Kang Long

2006-01-01

La 0.67 Mg 0.33 Ni 3.0-x Co x (x=0.0, 0.25, 0.50, 0.75) hydrogen storage alloys were prepared by induction melting. Influences of partial substitution of Co for Ni on phase structure and electrochemical properties of La 0.67 Mg 0.33 Ni 3.0 were investigated by means of X-ray diffraction (XRD), electron probe X-ray microanalysis (EPMA) and electrochemical measurements. XRD patterns and back scattered electron images show that the alloys were composed of the (La,Mg)Ni 3 phase with the PuNi 3 -type structure and the (La,Mg) 2 Ni 7 phase with the Ce 2 Ni 7 -type structure. The lattice parameters a, c and the unit-cell volumes v vary with the increase of Co content x. The electrochemical measurements show that partial Co substitution for Ni had no influence on the initial activation rate of the alloys. The maximum electrochemical discharge capacity increases firstly then decreases, the high-rate dischargeabilities (HRDs) of La 0.67 Mg 0.33 Ni 3.0-x Co x alloy electrodes increase with the increase of Co content. Moreover, the cycle stabilities of La 0.67 Mg 0.33 Ni 3.0-x Co x is not improved by small quantity replacement Ni by Co except for x=0.75

Investigation of nanocrystalline Gd films loaded with hydrogen

KAUST Repository

Hruška, Petr; Čí žek, Jakub; Dobroň, Patrik; Anwand, Wolfgang; Mü cklich, Arndt; Gemma, Ryota; Wagner, Stefan; Uchida, Helmut; Pundt, Astrid

2015-01-01

The present work reports on microstructure studies of hydrogen-loaded nanocrystalline Gd films prepared by cold cathode beam sputtering on sapphire (112¯0) substrates. The Gd films were electrochemically step-by-step charged with hydrogen and the structural development with increasing concentration of absorbed hydrogen was studied by transmission electron microscopy and in-situ   X-ray diffraction using synchrotron radiation. The relaxation of hydrogen-induced stresses was examined by acoustic emission measurements. In the low concentration range absorbed hydrogen occupies preferentially vacancy-like defects at GBs typical for nanocrystalline films. With increasing hydrogen concentration hydrogen starts to occupy interstitial sites. At the solid solution limit the grains gradually transform into the ββ-phase (GdH2). Finally at high hydrogen concentrations xH>2.0xH>2.0 H/Gd, the film structure becomes almost completely amorphous. Contrary to bulk Gd specimens, the formation of the γγ-phase (GdH3) was not observed in this work.

Laser-driven nuclear-polarized hydrogen internal gas target

International Nuclear Information System (INIS)

Seely, J.; Crawford, C.; Clasie, B.; Xu, W.; Dutta, D.; Gao, H.

2006-01-01

We report the performance of a laser-driven polarized internal hydrogen gas target (LDT) in a configuration similar to that used in scattering experiments. This target used the technique of spin-exchange optical pumping to produce nuclear spin polarized hydrogen gas that was fed into a cylindrical storage (target) cell. We present in this paper the performance of the target, methods that were tried to improve the figure-of-merit (FOM) of the target, and a Monte Carlo simulation of spin-exchange optical pumping. The dimensions of the apparatus were optimized using the simulation and the experimental results were in good agreement with the results from the simulation. The best experimental result achieved was at a hydrogen flow rate of 1.1x10 18 atoms/s, where the sample beam exiting the storage cell had 58.2% degree of dissociation and 50.5% polarization. Based on this measurement, the atomic fraction in the storage cell was 49.6% and the density averaged nuclear polarization was 25.0%. This represents the highest FOM for hydrogen from an LDT and is higher than the best FOM reported by atomic beam sources that used storage cells

Effect of calcium on the electrochemical behavior of lithium anode in LiOH aqueous solution used for lithium–water battery

International Nuclear Information System (INIS)

Zhang Ziyan; Chen Kanghua; Ni Erfu

2012-01-01

The effect of minor addition of calcium to lithium anode on the electrochemical behavior of lithium anode in 4 M LiOH at 30 °C temperature is investigated by hydrogen collection, polarization curves and electrochemical impedance spectroscopy. The results show that the hydrogen evolution rate is marginally reduced with increasing calcium content. Addition of calcium to lithium mainly inhibits the anodic process. Minor addition of calcium to lithium slightly reduced the discharge current of lithium anode. Minor addition of calcium to lithium anode marginally enhances the hydrogen inhibition of lithium by the formation of calcium hydride combined with LiOH and LiOH·H 2 O formed on the anode surface.

Hydrogen and renewable energy sources integrated system for greenhouse heating

Directory of Open Access Journals (Sweden)

Ileana Blanco

2013-09-01

Full Text Available A research is under development at the Department of Agro- Environmental Sciences of the University of Bari “Aldo Moro” in order to investigate the suitable solutions of a power system based on solar energy (photovoltaic and hydrogen, integrated with a geothermal heat pump for powering a self sustained heated greenhouse. The electrical energy for heat pump operation is provided by a purpose-built array of solar photovoltaic modules, which supplies also a water electrolyser system controlled by embedded pc; the generated dry hydrogen gas is conserved in suitable pressured storage tank. The hydrogen is used to produce electricity in a fuel cell in order to meet the above mentioned heat pump power demand when the photovoltaic system is inactive during winter night-time or the solar radiation level is insufficient to meet the electrical demand. The present work reports some theoretical and observed data about the electrolyzer operation. Indeed the electrolyzer has required particular attention because during the experimental tests it did not show a stable operation and it was registered a performance not properly consistent with the predicted performance by means of the theoretical study.

Solar driven technologies for hydrogen production

Directory of Open Access Journals (Sweden)

Medojević Milovan M.

2016-01-01

Full Text Available Bearing in mind that the production of hydrogen based on renewable energy sources, without doubt, is an important aspect to be taken into account when considering the potential of this gas, where as particularly interesting technologies stand out the ones which are based on the use of solar energy to produce hydrogen. The goal of this paper provides basic technological trajectories, with the possibility of combining, for solar driven hydrogen production, such as: electrochemical, photochemical and thermochemical process. Furthermore, the paper presents an analysis of those technologies from a technical as well as economic point of view. In addition, the paper aims to draw attention to the fact that the generation of hydrogen using renewable energy should be imposed as a logical and proper way to store solar energy in the form of chemical energy.

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)

Self-Powered Electrochemical Lactate Biosensing

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Ankit Baingane

2017-10-01

Full Text Available This work presents the development and characterization of a self-powered electrochemical lactate biosensor for real-time monitoring of lactic acid. The bioanode and biocathode were modified with D-lactate dehydrogenase (D-LDH and bilirubin oxidase (BOD, respectively, to facilitate the oxidation and reduction of lactic acid and molecular oxygen. The bioelectrodes were arranged in a parallel configuration to construct the biofuel cell. This biofuel cell’s current–voltage characteristic was analyzed in the presence of various lactic acid concentrations over a range of 1–25 mM. An open circuit voltage of 395.3 mV and a short circuit current density of 418.8 µA/cm² were obtained when operating in 25 mM lactic acid. Additionally, a 10 pF capacitor was integrated via a charge pump circuit to the biofuel cell to realize the self-powered lactate biosensor with a footprint of 1.4 cm × 2 cm. The charge pump enabled the boosting of the biofuel cell voltage in bursts of 1.2–1.8 V via the capacitor. By observing the burst frequency of a 10 pF capacitor, the exact concentration of lactic acid was deduced. As a self-powered lactate sensor, a linear dynamic range of 1–100 mM lactic acid was observed under physiologic conditions (37 °C, pH 7.4 and the sensor exhibited an excellent sensitivity of 125.88 Hz/mM-cm2. This electrochemical lactate biosensor has the potential to be used for the real-time monitoring of lactic acid level in biological fluids.

241-SY-101 mixer pump lifetime expectancy. Final report

International Nuclear Information System (INIS)

Shaw, C.P.

1995-01-01

The purpose of WHC-SD-WM-TI-726, Rev. 0 241-SY-101 Mixer Pump Lifetime Expectancy is to determine a best estimate of the mean lifetime of non-repairable (located in the waste) essential features of the hydrogen mitigation mixer pump presently installed in 101-SY. The estimated mean lifetime is 9.1 years. This report does not demonstrate operation of the entire pump assembly within the Tank Farm ''safety envelope''. It was recognized by the Defense Nuclear Facilities Safety Board (DNFSB) this test pump was not specifically designed for long term service in tank 101-SY. In June 95 the DNFSB visited Hanford and ask the question, ''how long will this test pump last and how will the essential features fail?'' During the 2 day meeting with the DNFSB it was discussed and defined within the meeting just exactly what essential features of the pump must operate. These essential features would allow the pump to operate for the purpose of extending the window for replacement. Operating with only essential features would definitely be outside the operating safety envelope and would require a waiver. There are three essential features: 1. The pump itself (i.e. the impeller and motor) must operate 2. Nozzles and discharges leg must remain unplugged 3. The pump can be re-aimed, new waste targeted, even if manually

The electrochemical characteristics of Mg2Ni nanocrystalline hydrogen storage alloy

International Nuclear Information System (INIS)

Zhang Ling; Zhou Xiaosong; Peng Shuming

2008-06-01

The nanocrystalline Mg 2 Ni materials were prepared by mechanical alloying. The cyclic voltametry results indicated that the potential of oxidation peak was shift as the scan rate increased and the absorption property of Mg 2 Ni prepared by mechanical alloying was increased even at ambient temperature. The absorption and desorption of hydrogen in Mg 2 Ni alloy were remarkably accelerated with the rising temperature. Small angel X-ray scattering results indicated that the Mg 2 Ni powder have 1-5 nm and 5-10 nm particle size distribution, which increased the acting sites of hydrogen absorption/desorption reaction and decreased the diffusion path of hydrogen desorption. It was induced to the enhanced performance of Mg 2 Ni nanocrystalline powder. The cycle life investigated results indicated that the activation property of Mg 2 Ni nanocrystal-line hydrogen storage alloy electrode was excellent, the capacitance maintenance ration was 66% after 200 cycles. The coating of epoxy resin on one side of the electrode had no effect on the activation property and the capacitance maintenance ration was better than the uncoating one. But the anode peak current value and the cathodic peak current value were decreased remarkably which indicated that the hydrogen absorption/desorption rate and the charge/discharge degree had decreased. (authors)

Electrochemical impedance spectroscopy study of the metal hydride alloy/electrolyte junction

International Nuclear Information System (INIS)

Khaldi, Chokri; Mathlouthi, Hamadi; Lamloumi, Jilani

2009-01-01

The behaviour of the LaNi 3.55 Mn 0.4 Al 0.3 Co 0.75 alloy, used as a negative electrode in the Ni-MH batteries, was studied by the electrochemical impedance spectroscopy (EIS), measured at different potentials. The modeling of the EIS spectra allows us to model the interface electrolyte/Ni-MH electrode by a succession of interfaces electrolyte/corrosion film/alloy particles. The various processes and the physics parameters of each interface are discussed and evaluated. When the potential shifts to more negative values, two reactions are in competition: the hydrogen molecular evolution and the hydrogen atomic absorption. The hydrogen diffuses in the bulk of the alloy and the diffusion is not the limiting factor for the hydrogen absorption.

Hydrogen injection device in BWR type reactor

International Nuclear Information System (INIS)

Takagi, Jun-ichi; Kubo, Koji.

1988-01-01

Purpose: To reduce the increasing ratio of main steam system dose rate due to N-16 activity due to excess hydrogen injection in the hydrogen injection operation of BWR type reactors. Constitution: There are provided a hydrogen injection mechanism for injecting hydrogen into primary coolants of a BWR type reactor, and a chemical injection device for injecting chemicals such as methanol, which makes nitrogen radioisotopes resulted in the reactor water upon hydrogen injection non-volatile, into the pressure vessel separately from hydrogen. Injected hydrogen and the chemicals are not reacted in the feedwater system, but the reaction proceeds due to the presence of radioactive rays after the injection into the pressure vessel. Then, hydrogen causes re-combination in the downcomer portion to reduce the dissolved oxygen concentration. Meanwhile, about 70 % of the chemicals is supplied by means of a jet pump directly to the reactor core, thereby converting the chemical form of N-16 in the reactor core more oxidative (non-volatile). (Kawakami, Y.)

(Case Study: Wastewater Pump Station of Khoramabad

Directory of Open Access Journals (Sweden)

Masoud Taheriyoun

2014-10-01

Full Text Available Evaluation of a Biofilter System for Removal of Hydrogen Sulfide Gas (Case Study: Wastewater Pump Station of Khorramabad Abstract The biofilter system is one of the methods commonly used for the removal of hydrogen sulfide as the main source of odors emitted from wastewater facilities. The system is based on using the contaminant material as bedding to feed microorganisms. To achieve the desirable removal efficiency, it is, therefore, essential to create the proper conditions for the bacteria to grow on the bedding. In this study, a pilot-scale biofilter made of compost and woodchip (with a compost/woodchip ratio of 5:1 was used as the bedding material at Khorrmabad wastewater pumping station to investigate the performance of the system under real conditions. The experiment was carried out over 75 days during which time the input and output H2S concentrations were measured on a regular basis. Moisture was adjusted between 40% and 60% throughout the experiment to provide optimal conditions for bacterial growth. The results showed that the concentration of H2S emitted from the pumping station during 24 hours varied greatly between 0 and 48 PPM. The maximum adsorption capacity of the biological bedding was recorded at 2.874 g/m3.hr and the mean efficiency of H2S removal including the startup time was 89%. The mean performance efficiency during the biological activity after the startup was recorded at 98%.

Enhanced Hydrogen Storage Capacity over Electro-synthesized HKUST-1

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Witri Wahyu Lestari

2017-12-01

Full Text Available HKUST-1 [Cu3(1,3,5-BTC2] (BTC = benzene-tri-carboxylate was synthesized using an electrochemical method and tested for hydrogen storage. The obtained material showed a remarkably higher hydrogen uptake over reported HKUST-1 and reached until 4.75 wt% at room temperature and low pressure up to 1.2 bar. This yield was compared to HKUST-1 obtained from the solvothermal method, which showed a hydrogen uptake of only 1.19 wt%. Enhancement of hydrogen sorption of the electro-synthesized product was due to the more appropriate surface area and pore size, effected by the preferable physical interaction between the hydrogen gasses and the copper ions as unsaturated metal centers in the frameworks of HKUST-1.

Synthesis of tantalum carbide and nitride nanoparticles using a reactive mesoporous template for electrochemical hydrogen evolution

KAUST Repository

Alhajri, Nawal Saad; Yoshida, Hiroshi; Anjum, Dalaver H.; Garcia Esparza, Angel T.; Kubota, Jun; Domen, Kazunari; Takanabe, Kazuhiro

2013-01-01

Tantalum carbide and nitride nanocrystals were prepared through the reaction of a tantalum precursor with mesoporous graphitic (mpg)-C 3N4. The effects of the reaction temperature, the ratio of the Ta precursor to the reactive template (mpg-C3N4), and the selection of the carrier gas (Ar, N2 and NH3) on the resultant crystal phases and structures were investigated. The produced samples were characterized using powder X-ray diffraction (XRD), CHN elemental analyses, thermogravimetric analyses (TGA), nitrogen sorption, a temperature-programmed reaction with mass spectroscopy (MS), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The results indicate that the different tantalum phases with cubic structure, TaN, Ta2CN, and TaC, can be formed under a flow of nitrogen when formed at different temperatures. The Ta3N5 phase with a Ta5+ oxidation state was solely obtained at 1023 K under a flow of ammonia, which gasified the C 3N4 template and was confirmed by detecting the decomposed gaseous products via MS. Significantly, the formation of TaC, Ta2CN, and TaN can be controlled by altering the weight ratio of the C 3N4 template relative to the Ta precursor at 1573 K under a flow of nitrogen. The high C3N4/Ta precursor ratio generally resulted in high carbide content rather than a nitride one, consistent with the role of mpg-C3N4 as a carbon source. Electrochemical measurements revealed that the synthesized nanomaterials were consistently able to produce hydrogen under acidic conditions (pH 1). The obtained Tafel slope indicates that the rate-determining step is the Volmer discharge step, which is consistent with adsorbed hydrogen being weakly bound to the surface during electrocatalysis. © 2013 The Royal Society of Chemistry.

Reduced Graphene Oxide Coating with Anticorrosion and Electrochemical Property-Enhancing Effects Applied in Hydrogen Storage System.

Science.gov (United States)

Du, Yi; Li, Na; Zhang, Tong-Ling; Feng, Qing-Ping; Du, Qian; Wu, Xing-Hua; Huang, Gui-Wen

2017-08-30

Low-capacity retention is the most prominent problem of the magnesium nickel alloy (Mg 2 Ni), which prevents it from being commercially applied. Here, we propose a practical method for enhancing the cycle stability of the Mg 2 Ni alloy. Reduced graphene oxide (rGO) possesses a graphene-based structure, which could provide high-quality barriers that block the hydroxyl in the aqueous electrolyte; it also possesses good hydrophilicity. rGO has been successfully coated on the amorphous-structured Mg 2 Ni alloy via electrostatic assembly to form the rGO-encapsulated Mg 2 Ni alloy composite (rGO/Mg 2 Ni). The experimental results show that ζ potentials of rGO and the modified Mg 2 Ni alloy are totally opposite in water, with values of -11.0 and +22.4 mV, respectively. The crumpled structure of rGO sheets and the contents of the carbon element on the surface of the alloy are measured using scanning electron microscopy, transmission electron microscopy, and energy dispersive spectrometry. The Tafel polarization test indicates that the rGO/Mg 2 Ni system exhibits a much higher anticorrosion ability against the alkaline solution during charging/discharging. As a result, high-capacity retentions of 94% (557 mAh g -1 ) at the 10th cycle and 60% (358 mAh g -1 ) at the 50th cycle have been achieved, which are much higher than the results on Mg 2 Ni capacity retention combined with the absolute value reported so far to our knowledge. In addition, both the charge-transfer reaction rate and the hydrogen diffusion rate are proven to be boosted with the rGO encapsulation. Overall, this work demonstrates the effective anticorrosion and electrochemical property-enhancing effects of rGO coating and shows its applicability in the Mg-based hydrogen storage system.

Hydrogen production by alkaline water electrolysis

Directory of Open Access Journals (Sweden)

Diogo M. F. Santos

2013-01-01

Full Text Available Water electrolysis is one of the simplest methods used for hydrogen production. It has the advantage of being able to produce hydrogen using only renewable energy. To expand the use of water electrolysis, it is mandatory to reduce energy consumption, cost, and maintenance of current electrolyzers, and, on the other hand, to increase their efficiency, durability, and safety. In this study, modern technologies for hydrogen production by water electrolysis have been investigated. In this article, the electrochemical fundamentals of alkaline water electrolysis are explained and the main process constraints (e.g., electrical, reaction, and transport are analyzed. The historical background of water electrolysis is described, different technologies are compared, and main research needs for the development of water electrolysis technologies are discussed.

Electrochemical stability of ionic clathrate hydrates and their structural consideration

International Nuclear Information System (INIS)

Lee, Wonhee; Lim, Dongwook; Lee, Huen

2013-01-01

Although electrochemical stability is an essential factor in relation to the potential applications of ionic clathrate hydrates to solid electrolytes, most studies regarding the proton conductors have focused on their ionic conductivity and thermal stability. Solid electrolytes in various electrochemical devices have to endure the applied potentials; thus, we examined the linear sweep voltammograms of various tetraalkylammonium hydroxide hydrates in order to shed light on the trend of electrochemical stability depending on the hydrate structure. We revealed that the electrochemical stability of Me 4 NOH hydrates is mainly affected by both their ionic concentration and cage occupancy. In particular, the true clathrate structures of β-Me 4 NOH hydrates are more electrochemically stable than their α-forms that possess partially broken hydrogen bonds. We also observed that the binary THF–Pr 4 NOH and pure Bu 4 NOH clathrate hydrates exhibit greater electrochemical stability than those of pure Me 4 NOH hydrates having lower or similar ionic concentrations. These results are considered to arise from the fact that each of the Pr 4 N + and Bu 4 N + ions occupies an extended space comprising four cages, which leads to stabilization of the larger unit, whereas a Me 4 N + ion is completely included only in one cage

Multi-Scale Ordered Cell Structure for Cost Effective Production of Hydrogen by HTWS

Energy Technology Data Exchange (ETDEWEB)

Elangovan, Elango [Ceramatec, Inc., West Valley City, UT (United States); Rao, Ranjeet [PARC, Palo Alto, CA (United States); Colella, Whitney [Gaia Energy Research Inst. LLC, Arlington, VA (United States)

2017-12-20

Production of hydrogen using an electrochemical device provides for large scale, high efficiency conversion and storage of electrical energy. When renewable electricity is used for conversion of steam to hydrogen, a low-cost and low emissions pathway to hydrogen production emerges. This project was intended to demonstrate a high efficiency High Temperature Water Splitting (HTWS) stack for the electrochemical production of low cost H2. The innovations investigated address the limitations of the state of the art through the use of a novel architecture that introduces macro-features to provide mechanical support of a thin electrolyte, and micro-features of the electrodes to lower polarization losses. The approach also utilizes a combination of unique sets of fabrication options that are scalable to achieve manufacturing cost objectives. The development of HTWS process and device is guided by techno-economic and life cycle analyses.

Electrochemical reduction of hydrogen peroxide on stainless steel

Indian Academy of Sciences (India)

Administrator

wide range of industrial processes such as food processing (e.g. in the ... tron transfer effect of mitochondria.4 These radicals. (reactive .... of H2O2 without undergoing fouling or poisoning due to any inter- .... adsorbed OHads species was shown operative at po- tentials of .... Douglass W C 2003 Hydrogen peroxide medical.

Studies of Modified Hydrogen Storage Intermetallic Compounds Used as Fuel Cell Anodes

Directory of Open Access Journals (Sweden)

Rui F. M. Lobo

2011-12-01

Full Text Available The possibility of substituting Pt/C with the hydrogen storage alloy MlNi3.6Co0.85Al0.3Mn0.3 as the anode active material of a proton exchange membrane fuel cell system has been analyzed. The electrochemical properties indicate that a much more electrochemically active anode is obtained by impregnating the active material loaded anode in a Nafion proton conducting polymer. Such performance improvement might result from the increase of three-phase boundary sites or length in the gas diffusion electrode where the electrochemical reaction occurs. The experimental data revealed that the membrane electrode assembly (MEA shows better results when the anode active material, MlNi3.6Co0.85Al0.3Mn0.3, is treated with a hot alkaline KBH4 solution, and then chemically coated with 3 wt.% Pd. The MEA with the aforesaid modification presents an enhanced surface capability for hydrogen adsorption, and has been studied by molecular beam-thermal desorption spectrometry.

ELECTROCHEMICAL BEHAVIOR OF POLYCRYSTALLINE COPPER DURING THE ADSORPTION OF CO ABSTRACT

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J. Salimon

2017-12-01

Full Text Available The electrochemical properties of electrode copper in carbon monoxide-saturated phosphate buffered solution were investigated. The electrochemistry of copper surface was sufficiently changed after the supporting electrolyte solution was saturated with CO. The hydrogen evolution region was depressed and shifted cathodically due to the adsorption process of CO on the copper surface in a linear or terminally bonded manner, Cu-CO . The oxidation and the reduction peaks of copper were significantly changed with two couple of redox peaks. This is due to the subsequent formation and the corresponding reduction of copper(I and the copper carbon monoxides species. Further changed in electrochemical properties occurred when the electrode surface was polarized at high cathodic potential (-1.4 V for a period of time (15 min. The hydrogen evolution region was further depressed due to the adsorption of CO process in multiple bonding sites as adsorbed bridge bonded CO, Cu-CO B L that occurred predominantly.

Hydrogen-Oxygen PEM Regenerative Fuel Cell at NASA Glenn Research Center

Science.gov (United States)

Bents, David J.

2004-01-01

The NASA Glenn Research Center has constructed a closed-cycle hydrogen-oxygen PEM regenerative fuel cell (RFC) to explore its potential use as an energy storage device for a high altitude solar electric aircraft. Built up over the last 2 years from specialized hardware and off the shelf components the Glenn RFC is a complete "brassboard" energy storage system which includes all the equipment required to (1) absorb electrical power from an outside source and store it as pressurized hydrogen and oxygen and (2) make electrical power from the stored gases, saving the product water for re-use during the next cycle. It consists of a dedicated hydrogen-oxygen fuel cell stack and an electrolyzer stack, the interconnecting plumbing and valves, cooling pumps, water transfer pumps, gas recirculation pumps, phase separators, storage tanks for oxygen (O2) and hydrogen (H2), heat exchangers, isolation valves, pressure regulators, nitrogen purge provisions, instrumentation, and other components. It specific developmental functions include: (1) Test fuel cells and fuel cell components under repeated closed-cycle operation (nothing escapes; everything is used over and over again). (2) Simulate diurnal charge-discharge cycles (3) Observe long-term system performance and identify degradation and loss mechanisms. (4) Develop safe and convenient operation and control strategies leading to the successful development of mission-capable, flight-weight RFC's.

Hydrogen-Assisted IC Engine Combustion as a Route to Hydrogen Implementation

Energy Technology Data Exchange (ETDEWEB)

Andre Boehman; Daniel Haworth

2008-09-30

The 'Freedom Car' Initiative announced by the Bush Administration has placed a significant emphasis on development of a hydrogen economy in the United States. While the hydrogen-fueled fuel-cell vehicle that is the focus of the 'Freedom Car' program would rely on electrochemical energy conversion, and despite the large amount of resources being devoted to its objectives, near-term implementation of hydrogen in the transportation sector is not likely to arise from fuel cell cars. Instead, fuel blending and ''hydrogen-assisted'' combustion are more realizable pathways for wide-scale hydrogen utilization within the next ten years. Thus, a large potential avenue for utilization of hydrogen in transportation applications is through blending with natural gas, since there is an existing market for natural-gas vehicles of various classes, and since hydrogen can provide a means of achieving even stricter emissions standards. Another potential avenue is through use of hydrogen to 'assist' diesel combustion to permit alternate combustion strategies that can achieve lower emissions and higher efficiency. This project focused on developing the underlying fundamental information to support technologies that will facilitate the introduction of coal-derived hydrogen into the market. Two paths were envisioned for hydrogen utilization in transportation applications. One is for hydrogen to be mixed with other fuels, specifically natural gas, to enhance performance in existing natural gas-fueled vehicles (e.g., transit buses) and provide a practical and marketable avenue to begin using hydrogen in the field. A second is to use hydrogen to enable alternative combustion modes in existing diesel engines, such as homogeneous charge compression ignition, to permit enhanced efficiency and reduced emissions. Thus, this project on hydrogen-assisted combustion encompassed two major objectives: (1) Optimization of hydrogen-natural gas mixture

High-temperature electrochemical performance of low-cost La–Ni–Fe based hydrogen storage alloys with different preparation methods

Energy Technology Data Exchange (ETDEWEB)

Wang, Qiannan [Department of Advanced Energy Materials, College of Materials Science and Engineering, Sichuan University, Chengdu 610065 (China); Zhu, Ding [Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610065 (China); Zhou, Wanhai; Zhong, Chenglin; Wu, Chaoling [Department of Advanced Energy Materials, College of Materials Science and Engineering, Sichuan University, Chengdu 610065 (China); Chen, Yungui, E-mail: ygchen60@aliyun.com [Department of Advanced Energy Materials, College of Materials Science and Engineering, Sichuan University, Chengdu 610065 (China); Institute of New Energy and Low-Carbon Technology, Sichuan University, Chengdu 610065 (China)

2016-04-15

Highlights: • Effects of four different preparation processes were studied at 20/60 °C. • All NS + HT, RS and RS + HT processes can optimize the thermodynamic performance. • The HT process can provoke the precipitation of A{sub 2}B{sub 7} and leads to a poor cycling life. • Al exhibits the most remarkable dissolution for all the alloys, especially at 60 °C. - Abstract: In order to optimize the microstructure and high temperature electrochemical performances of low-cost AB{sub 5}-type Ml(NiMnAl){sub 4.2}Co{sub 0.3}Fe{sub 0.5} hydrogen storage electrode alloys, four different preparation methods including normal solidification (NS), normal solidification and 900 °C heat treatment (NS + HT), rapid solidification (RS), rapid solidification and 900 °C heat treatment (RS + HT) were adopted in this work. All alloys exhibit CaCu{sub 5} type hexagonal structure and there is a small amount of A{sub 2}B{sub 7} phase in NS + HT and RS + HT alloys. It is found the using of HT process can decrease the hydrogen equilibrium plateau pressure, the plateau slope and hysteresis at 40, 60 and 80 °C. The NS + HT and RS + HT alloys also possess better activation, high rate discharge performance, larger discharge capacity, but poor cycling performance due to the existence of A{sub 2}B{sub 7} phase which can accelerate dissolution of Ni, Mn and Fe elements in KOH alkaline electrolyte. The RS process can make alloy exhibit the best cycling performance especially at 60 °C.

Photo-electrochemical Investigation of Radiation-Enhanced Galvanic Coupling and Hydrogen Permeation in TPBAR-related Materials

Energy Technology Data Exchange (ETDEWEB)

Larsen, G. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2017-10-02

Research conducted in FY17 used photo-electrochemical methods to investigate the potential for radiationenhanced galvanic coupling in tritium-producing burnable absorber rod (TPBAR) materials. Specifically, a laboratory electrochemical cell was coupled with UV light in order to perform electrochemical opencircuit voltage and galvanic current measurements, techniques that have been used successfully in previous studies to replicate galvanic processes in reactor settings. UV irradiation can mimic reactor-like behavior because, similar to both directly and indirectly ionizing radiation, UV photons with energy greater than the band gap of the material will generate free charge carriers (electrons and holes) and can substantially alter the passivating effect of metal oxides.

Photo-electrochemical Investigation of Radiation-Enhanced Galvanic Coupling and Hydrogen Permeation in TPBAR-related Materials

International Nuclear Information System (INIS)

Larsen, G.

2017-01-01

Research conducted in FY17 used photo-electrochemical methods to investigate the potential for radiationenhanced galvanic coupling in tritium-producing burnable absorber rod (TPBAR) materials. Specifically, a laboratory electrochemical cell was coupled with UV light in order to perform electrochemical opencircuit voltage and galvanic current measurements, techniques that have been used successfully in previous studies to replicate galvanic processes in reactor settings. UV irradiation can mimic reactor-like behavior because, similar to both directly and indirectly ionizing radiation, UV photons with energy greater than the band gap of the material will generate free charge carriers (electrons and holes) and can substantially alter the passivating effect of metal oxides.

Carbon paste electrode with covalently immobilized thionine for electrochemical sensing of hydrogen peroxide

Science.gov (United States)

Thenmozhi, K.; Sriman Narayanan, S.

2017-11-01

A water-soluble redox mediator, thionin was covalently immobilized to the functionalized graphite powder and a carbon paste electrode was fabricated from this modified graphite powder. The immobilization procedure proved to be effective in anchoring the thionin mediator in the graphite electrode setup without any leakage problem during the electrochemical studies. The covalent immobilization of the thionin mediator was studied with FT-IR and the electrochemical response of the thionin carbon paste electrode was optimized on varying the supporting electrolyte, pH and scan rate. The modified electrode exhibited well-defined electrocatalytic activity towards the reduction of H2O2 at a lower potential of -0.266 V with good sensitivity. The developed amperometric sensor was efficient towards H2O2 in the linear range from 2.46 × 10-5 M to 4.76 × 10-3 M, with a detection limit of 1.47 × 10-5 M respectively. Important advantages of this sensor are its excellent electrochemical performance, simple fabrication, easy renewability, reproducible analytical results, acceptable accuracy and good operational and long-term stability.

Modified porous silicon for electrochemical sensor of para-nitrophenol

International Nuclear Information System (INIS)

Belhousse, S.; Belhaneche-Bensemra, N.; Lasmi, K.; Mezaache, I.; Sedrati, T.; Sam, S.; Tighilt, F.-Z.; Gabouze, N.

2014-01-01

Highlights: • Hybrid device based on Porous silicon (PSi) and polythiophene (PTh) was prepared. • Three types of PSi/PTh hybrid structures were elaborated: PSi/PTh, oxide/PSi/PTh and Amino-propyltrimethoxysilane (APTMES)/oxide/PSi/PTh. • PTh was grafted on PSi using electrochemical polymerization. • The electrodetection of para-nitrophenol (p-NPh) was performed by cyclic voltammetry. • Oxide/PSi/PTh and APTMES/oxide/PSi/PTh, based electrochemical sensor showed a good response toward p-NPh. - Abstract: Hybrid structures based on polythiophene modified porous silicon was used for the electrochemical detection of para-nitrophenol, which is a toxic derivative of parathion insecticide and it is considered as a major toxic pollutant. The porous silicon was prepared by anodic etching in hydrofluodic acid. Polythiophene films were then grown by electropolymerisation of thiophene monomer on three different surfaces: hydrogenated PSi, oxidized PSi and amine-terminated PSi. The morphology of the obtained structures were observed by scanning electron microscopy and characterized by spectroscopy (FTIR). Cyclic voltammetry was used to study the electrochemical response of proposed structures to para-nitrophenol. The results show a high sensitivity of the sensor and a linearity of the electrochemical response in a large concentration interval ranging from 1.5 × 10 −8 M to the 3 × 10 −4 M

Polyaniline nanowires-gold nanoparticles hybrid network based chemiresistive hydrogen sulfide sensor

Science.gov (United States)

Shirsat, Mahendra D.; Bangar, Mangesh A.; Deshusses, Marc A.; Myung, Nosang V.; Mulchandani, Ashok

2009-02-01

We report a sensitive, selective, and fast responding room temperature chemiresistive sensor for hydrogen sulfide detection and quantification using polyaniline nanowires-gold nanoparticles hybrid network. The sensor was fabricated by facile electrochemical technique. Initially, polyaniline nanowires with a diameter of 250-320 nm bridging the gap between a pair of microfabricated gold electrodes were synthesized using templateless electrochemical polymerization using a two step galvanostatic technique. Polyaniline nanowires were then electrochemically functionalized with gold nanoparticles using cyclic voltammetry technique. These chemiresistive sensors show an excellent limit of detection (0.1 ppb), wide dynamic range (0.1-100 ppb), and very good selectivity and reproducibility.

Uses and evaluation methods of potential hydrogen permeation barriers for nuclear reactor materials

International Nuclear Information System (INIS)

Noga, J.O.; Piercy, G.R.; Bowker, J.T.

1985-07-01

This report summarizes results on the use of coatings as hydrogen permeation barriers on nuclear reactor component materials. Two classes of base materials were considered, exothermic hydrogen absorbers and endothermic hydrogen absorbers. The results of the tests indicate that substantial reductions in the amount of hydrogen absorbed by a metal can be achieved through the use of hydrogen permeation barrier coatings. Gold was determined to provide an effective hydrogen permeation barrier on Zr-2-1/2 Nb pressure tube material. Tin was determined to be a suitable hydrogen permeation barrier when applied on AISI 410 stainless steel and iron. Both gas phase and electrochemical permeation techniques were used to determine hydrogen permeabilities through coatings and base materials

Facile fabrication of nanoporous PdFe alloy for nonenzymatic electrochemical sensing of hydrogen peroxide and glucose

Energy Technology Data Exchange (ETDEWEB)

Wang, Jinping [Key Laboratory of Chemical Sensing and Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China); Wang, Zhihong [School of Basic Medical Sciences, Shandong University of Traditional Chinese Medicine, Jinan 250355 (China); Zhao, Dianyun [Key Laboratory of Chemical Sensing and Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China); Xu, Caixia, E-mail: chm_xucx@ujn.edu.cn [Key Laboratory of Chemical Sensing and Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022 (China)

2014-06-01

Graphical abstract: Nanoporous PdFe alloy, characterized by open three-dimensional bicontinuous nanospongy architecture, was easily fabricated by selectively dealloying PdFeAl source alloys, which exhibits greatly enhanced sensing performance and structure stability towards H{sub 2}O{sub 2} and glucose compared with NP-Pd and Pd/C catalysts. - Highlights: • NP-PdFe alloy is fabricated by a simple dealloying method. • NP-PdFe possesses open three-dimensional bicontinuous spongy morphology. • NP-PdFe shows high electrochemical sensing activities towards H{sub 2}O{sub 2} and glucose. • NP-PdFe shows good long-term stability for H{sub 2}O{sub 2} and glucose detection. • NP-PdFe shows good reproducibility for H{sub 2}O{sub 2} and glucose detection. - Abstract: Nanoporous (NP) PdFe alloy is easily fabricated through one step mild dealloying of PdFeAl ternary source alloy in NaOH solution. Electron microscopy characterization demonstrates that selectively dissolving Al from PdFeAl alloy generates three-dimensional bicontinuous nanospongy architecture with the typical ligament size around 5 nm. Electrochemical measurements show that the NP-PdFe alloy exhibits the superior electrocatalytic activity and durability towards hydrogen peroxide (H{sub 2}O{sub 2}) detection compared with NP-Pd and commercial Pd/C catalysts. In addition, NP-PdFe performs high sensing performance towards H{sub 2}O{sub 2} in a wide linear range from 0.5 to 6 mM with a low detection limit of 2.1 μM. This nanoporous structure also can sensitively detect glucose over a wide concentration range (1–32 mM) with a low detection limit of 1.6 μM and high resistance against chloride ions. Along with these attractive features, the as-made NP-PdFe alloy also has a good anti-interference towards ascorbic acid, uric acid, and dopamine.

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

Science.gov (United States)

Rieke, Peter C [Pasco, WA; Coffey, Gregory W [Richland, WA; Pederson, Larry R [Kennewick, WA; Marina, Olga A [Richland, WA; Hardy, John S [Richland, WA; Singh, Prabhaker [Richland, WA; Thomsen, Edwin C [Richland, WA

2010-07-20

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

Sodium pumping: pump problems

International Nuclear Information System (INIS)

Guer, M.; Guiton, P.

Information on sodium pumps for LMFBR type reactors is presented concerning ring pump design, pool reactor pump design, secondary pumps, sodium bearings, swivel joints of the oscillating annulus, and thermal shock loads

The monitoring of oxygen, hydrogen and carbon in the sodium circuits of the PFR

International Nuclear Information System (INIS)

Mason, L.; Morrison, N.S.; Robertson, C.M.; Trevillion, E.A.

1984-01-01

The paper reviews the instrumentation available for monitoring oxygen, hydrogen, tritium and carbon impurity levels on the primary and secondary circuits of PFR. Circuit oxygen levels measured using electrochemical oxygen meters are compared to estimates from circuit plugging meters. The data are interpreted in the light of information from cold trap temperatures. Measurements of secondary circuit hydrogen levels using both the sodium and gas phase hydrogen detection equipment are compared to estimates of circuit hydrogen levels from plugging meters and variations in sodium phase hydrogen levels during power operation are discussed. (author)

Silicon Nano wires with MoS_x and Pt as Electrocatalysts for Hydrogen Evolution Reaction

International Nuclear Information System (INIS)

Hsieh, S.H.; Ho, S.T.; Chen, W.J.

2016-01-01

A convenient method was used for synthesizing Pt-nanoparticle//silicon nano wires nano composites. Obtained Pt-/silicon nano wires electrocatalysts were characterized by transmission electron microscopy (TEM). The hydrogen evolution reaction efficiency of the Pt-/silicon nano wire nano composite catalysts was assessed by examining polarization and electrolysis measurements under solar light irradiations. The electrochemical characterizations demonstrate that Pt-/silicon nano wire electrodes exhibited an excellent catalytic activity for hydrogen evolution reaction in an acidic electrolyte. The hydrogen production capability of Pt-/silicon nano wires is also comparable to /silicon nano wires and Pt/silicon nano wires. Electrochemical impedance spectroscopy experiments suggest that the enhanced performance of Pt-/silicon nano wires can be attributed to the fast electron transfer between Pt-/silicon nano wire electrodes and electrolyte interfaces.

Driving of the solar p-modes by radiative pumping in the upper photosphere

Science.gov (United States)

Fontenla, Juan M.; Emslie, A. G.; Moore, Ronald L.

1989-01-01

It is shown that one viable driver of the solar p-modes is radiative pumping in the upper photosphere where the opacity is dominated by the negative hydrogen ion. This new option is suggested by the similar magnitudes of two energy flows that have been evaluated by independent empirical methods. The similarity indicates that the p-modes are radiatively pumped in the upper photosphere and therefore provide the required nonradiative cooling.

One-pot synthesis of MoS2/In2S3 ultrathin nanoflakes with mesh-shaped structure on indium tin oxide as photocathode for enhanced photo-and electrochemical hydrogen evolution reaction

Science.gov (United States)

Sun, Baoliang; Shan, Fei; Jiang, Xinxin; Ji, Jing; Wang, Feng

2018-03-01

A bifunctional MoS2/In2S3 hybrid composite that has both photo- and electrocatalytic activity toward hydrogen evolution reaction (HER) is prepared by a facile one pot hydrothermal method. The characterizations by scanning electron microscope (SEM), high resolution transmission electron microscope (HRTEM) and Photoluminescence (PL) shows that the MoS2/In2S3 hybrid exhibits ultrathin nanoflakes with mesh-shaped structure on transparent conductive substrates, and the as prepared catalyst composite obviously improves the separation of electro-hole pairs. The as prepared hybrid nanosheets with Mo:In of 1/2 integrate In-doped MoS2 to reduce the stacking and increase the active surface area. The novel mesh-shaped nanostructure with a moderate degree of disorder provides not only simultaneously intrinsic conductivity and defects but also higher electrochemically active surface area (ECSA). By electrochemical measurements, such as linear sweep voltammetry (LSV), electrochemical impedance spectroscope (EIS) and cyclic voltammetry (CV), we find that the MoS2/In2S3 hybrid possesses much better photo/electrochemical activity than pristine MoS2 or In2S3. MoS2/In2S3 ultrathin nanoflaks are anticipated to be a superior photoelectrocatalyst for PEC cells, and the rational use of the MoS2/In2S3 cathode offers a new avenue toward achieving effective photo-assistant electrocatalytic activity.

Novel Ag@TiO2 nanocomposite synthesized by electrochemically active biofilm for nonenzymatic hydrogen peroxide sensor

International Nuclear Information System (INIS)

Khan, Mohammad Mansoob; Ansari, Sajid Ali; Lee, Jintae; Cho, Moo Hwan

2013-01-01

A novel nonenzymatic sensor for H 2 O 2 was developed based on an Ag@TiO 2 nanocomposite synthesized using a simple and cost effective approach with an electrochemically active biofilm. The optical, structural, morphological and electrochemical properties of the as-prepared Ag@TiO 2 nanocomposite were examined by UV–vis spectroscopy, X-ray diffraction, transmission electron microscopy and cyclic voltammetry (CV). The Ag@TiO 2 nanocomposite was fabricated on a glassy carbon electrode (GCE) and their electrochemical performance was analyzed by CV, differential pulse voltammetry and electrochemical impedance spectroscopy. The Ag@TiO 2 nanocomposite modified GCE (Ag@TiO 2 /GCE) displayed excellent performance towards H 2 O 2 sensing at − 0.73 V in the linear response range from 0.83 μM to 43.3 μM, within a detection limit and sensitivity of 0.83 μM and ∼ 65.2328 ± 0.01 μAμM −1 cm −2 , respectively. In addition, Ag@TiO 2 /GCE exhibited good operational reproducibility and long term stability. - Graphical abstract: Synthesis of Ag@TiO 2 nanocomposite by electrochemically active biofilm for H 2 O 2 sensing. - Highlights: • Electrochemically active biofilm (EAB) • EAB mediated synthesis of Ag@TiO 2 nanocomposite • Ag@TiO 2 nanocomposite modified glassy carbon electrode • Ag@TiO 2 /GCE for H 2 O 2 sensing • Nonenzymatic sensor for H 2 O 2

How green are the hydrogen production processes?

International Nuclear Information System (INIS)

Miele, Ph.; Demirci, U.B.

2010-01-01

Molecular hydrogen is recognised as being one of the most promising fuels alternate to fossil fuels. Unfortunately it only exists combined with other elements like e.g. oxygen in the case of water and therefore has to be produced. Today various methods for producing molecular hydrogen are being investigated. Besides its energy potential, molecular hydrogen is regarded as being a green energy carrier because it can be produced from renewable sources and its combustion/oxidation generates water. However as it has to be produced its greenness merits a deeper discussion especially stressing on its production routes. The goal of the present article is to discuss the relative greenness of the various hydrogen production processes on the basis of the twelve principles of green chemistry. It is mainly showed that the combination 'renewable raw materials, biological or electrochemical methods, and renewable energies (e.g. solar or wind)' undeniably makes the hydrogen production green. (authors)

Effects of Nd-addition on the structural, hydrogen storage, and electrochemical properties of C14 metal hydride alloys

Energy Technology Data Exchange (ETDEWEB)

Wong, D.F. [BASF/Battery Materials-Ovonic, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States); Department of Chemical Engineering, Wayne State University, Detroit, MI 48202 (United States); Young, K., E-mail: kwo.young@basf.com [BASF/Battery Materials-Ovonic, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States); Department of Chemical Engineering, Wayne State University, Detroit, MI 48202 (United States); Nei, J.; Wang, L. [BASF/Battery Materials-Ovonic, 2983 Waterview Drive, Rochester Hills, MI 48309 (United States); Ng, K.Y.S. [Department of Chemical Engineering, Wayne State University, Detroit, MI 48202 (United States)

2015-10-25

Nd-addition to the AB{sub 2}-based alloy Ti{sub 12}Zr{sub 22.8−x}V{sub 10}Cr{sub 7.5}Mn{sub 8.1}Co{sub 7.0}Ni{sub 32.2}Al{sub 0.4}Nd{sub x} is studied for its effects on the structure, gaseous-phase hydrogen storage, and electrochemical properties. This study follows a series of Cu, Mo, Fe, Y, Si, and La doping studies in similar AB{sub 2}-based alloys. Limited solubility of Nd in the main Laves phase promotes the formation of secondary phases (AB and Zr{sub 7}Ni{sub 10}) to provide catalytic effects and synergies for improved capacity and high-rate dischargeability (HRD) performance. The main C14 storage phase has smaller lattice constants and cell volumes, and these effects reduce the storage capacity at higher Nd levels. Different hydrogen absorption mechanisms can occur in these multi-component, multi-phase alloys depending on the interfaces of the phases, and they have effects on the alloy properties. Higher Nd-levels improve the HRD performance despite having lower bulk diffusion and surface exchange current. Magnetic susceptibility measurements indicate large percentage of larger metallic nickel clusters are present in the surface oxide of alloys with higher Nd-content, and AC impedance studies show very low charge-transfer resistance with high catalytic capability in the alloys. The −40 °C charge-transfer resistance of 8.9 Ω g in this Nd-series of alloys is the lowest measured out of the studies investigating doped AB{sub 2}-based MH alloys for improved low-temperature characteristics. The improvement in HRD and low-temperature performance appears to be related to the proportion of the highly catalytic NdNi-phase at the surface, which must offset the increased bulk diffusion resistance in the alloy. - Graphical abstract: Schematics of hydrogen flow and corresponding PCT isotherms in funneling mode. - Highlights: • Structural and hydrogen storage properties of Nd-substituted AB{sub 2} metal hydride are reported. • Nd contributes to the lowest

Submersible fans and pumps for cryogenic fluids

International Nuclear Information System (INIS)

Mark, J.W.

1986-01-01

Submersible electric motor driven fans of three sizes have been designed, built and operated at 21 0 K at the Stanford Linear Accelerator Center. The largest is a 100-mm diameter, 2 stage vaneaxial fan with a nominal capacity of 6 L/s at 2 m head. It is driven by a 4 pole, 3 phase induction motor that runs at 1750 rpm. The next smaller one is an 85-mm diameter centrifugal pump. It pumps 3 L/s at a head of 5 m. The third is a 75-mm single stage vaneaxial fan with a nominal capacity is 3 L/s at a head of 2 m. The 85-mm pump and the 75-mm fan are driven by 2 pole, 3 phase induction motors running at 3550 rpm. The motors were modified to operate submerged in the cryogenic fluid. The pumps have been operated in liquid hydrogen, liquid deuterium, and pressurized helium gas at 21 0 K. They can also operate with denser fluids such as liquid nitrogen, but rotational speed, capacity, and head will be reduced. They have been operated while submerged in liquid helium

Optical pumping and xenon NMR

International Nuclear Information System (INIS)

Raftery, M.D.

1991-11-01

Nuclear Magnetic Resonance (NMR) spectroscopy of xenon has become an important tool for investigating a wide variety of materials, especially those with high surface area. The sensitivity of its chemical shift to environment, and its chemical inertness and adsorption properties make xenon a particularly useful NMR probe. This work discusses the application of optical pumping to enhance the sensitivity of xenon NMR experiments, thereby allowing them to be used in the study of systems with lower surface area. A novel method of optically-pumping 129 Xe in low magnetic field below an NMR spectrometer and subsequent transfer of the gas to high magnetic field is described. NMR studies of the highly polarized gas adsorbed onto powdered samples with low to moderate surface areas are now possible. For instance, NMR studies of optically-pumped xenon adsorbed onto polyacrylic acid show that xenon has a large interaction with the surface. By modeling the low temperature data in terms of a sticking probability and the gas phase xenon-xenon interaction, the diffusion coefficient for xenon at the surface of the polymer is determined. The sensitivity enhancement afforded by optical pumping also allows the NMR observation of xenon thin films frozen onto the inner surfaces of different sample cells. The geometry of the thin films results in interesting line shapes that are due to the bulk magnetic susceptibility of xenon. Experiments are also described that combine optical pumping with optical detection for high sensitivity in low magnetic field to observe the quadrupoler evolution of 131 Xe spins at the surface of the pumping cells. In cells with macroscopic asymmetry, a residual quadrupolar interaction causes a splitting in the 131 Xe NMR frequencies in bare Pyrex glass cells and cells with added hydrogen

Low-cost, high-performance nonevaporable getter pumps using nonevaporable getter pills

International Nuclear Information System (INIS)

Kodama, Hiraku; Ohno, Shinya; Tanaka, Masatoshi; Tanaka, Masato; Okudaira, Koji K.; Mase, Kazuhiko; Kikuchi, Takashi

2016-01-01

Nonevaporable getter (NEG) pumps are widely used for maintaining a clean ultrahigh vacuum (UHV) of ≤10"−"8" Pa because of their high pumping speeds for hydrogen (H_2) and active gases in the UHV region. In addition, they are oil free, evaporation free, sputtering free, sublimation free, magnetic field free, vibration free, economical, compact, lightweight, and energy saving. In the present paper, the authors report a new NEG pump which is composed of commercial 60 NEG pills (ϕ10 × 3 mm; 70 wt. % Zr, 24.6 wt. % V, and 5.4 wt. % Fe), titanium parts, a DN 40 conflat flange, and a tantalum heater. The NEG pills are vertically and radially aligned around the heater to maximize the effective area for pumping. After activation at 400 °C for 30 min, the pumping speeds of the NEG pump were measured with the orifice method. Pumping speeds of 140–130, 200–140, 190–130, and 35–17 l/s were estimated for H_2, CO, CO_2, and N_2 gasses, respectively, in a pumped-quantity range of 0.01–0.1 Pa l. Since the NEG pump is composed of a heating unit and a NEG module, the pumping speeds can be improved by increasing the number of NEG modules. These NEG pumps are favorable alternatives to sputtering ion pumps or titanium sublimation pumps.

Low-cost, high-performance nonevaporable getter pumps using nonevaporable getter pills

Energy Technology Data Exchange (ETDEWEB)

Kodama, Hiraku; Ohno, Shinya; Tanaka, Masatoshi [Faculty of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501 (Japan); Tanaka, Masato; Okudaira, Koji K. [Faculty of Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku 263-8522 (Japan); Mase, Kazuhiko, E-mail: mase@post.kek.jp; Kikuchi, Takashi [Institute of Materials Structure Science, KEK, 1-1 Oho, Tsukuba 305-0801 (Japan)

2016-09-15

Nonevaporable getter (NEG) pumps are widely used for maintaining a clean ultrahigh vacuum (UHV) of ≤10{sup −8 }Pa because of their high pumping speeds for hydrogen (H{sub 2}) and active gases in the UHV region. In addition, they are oil free, evaporation free, sputtering free, sublimation free, magnetic field free, vibration free, economical, compact, lightweight, and energy saving. In the present paper, the authors report a new NEG pump which is composed of commercial 60 NEG pills (ϕ10 × 3 mm; 70 wt. % Zr, 24.6 wt. % V, and 5.4 wt. % Fe), titanium parts, a DN 40 conflat flange, and a tantalum heater. The NEG pills are vertically and radially aligned around the heater to maximize the effective area for pumping. After activation at 400 °C for 30 min, the pumping speeds of the NEG pump were measured with the orifice method. Pumping speeds of 140–130, 200–140, 190–130, and 35–17 l/s were estimated for H{sub 2}, CO, CO{sub 2}, and N{sub 2} gasses, respectively, in a pumped-quantity range of 0.01–0.1 Pa l. Since the NEG pump is composed of a heating unit and a NEG module, the pumping speeds can be improved by increasing the number of NEG modules. These NEG pumps are favorable alternatives to sputtering ion pumps or titanium sublimation pumps.

Reliability of Electrochemical Techniques for Determining Corrosion Rates on Carbon Steel in Sulfide Media

DEFF Research Database (Denmark)

Hilbert, Lisbeth Rischel; Hemmingsen, T.; Nielsen, Lars Vendelbo

2007-01-01

if the biofilm in combination with ferrous sulfide corrosion products cover the steel surface. Corrosion rates can be overestimated by a factor of 10 to 100 with electrochemical techniques - both by linear polarization resistance (LPR) and electrochemicel impedance spectroscopy (EIS). Oxygen entering the system......Effects of film formation on carbon steel in hydrogen sulfide (H2S) media may corrupt corrosion rate monitoring by electrochemical techniques. Electrochemical data from H2S solutions, biological sulfide media, and natural sulfide containing geothermal water have been collected, and the process...... of film formation in sulfide solutins was followed by video. It can be shown that capacitative and diffusional effects due to porous reactive deposits tend to dominate the data, resulting in unreliable corrosion rates measured using electrochemical techniques. The effect is strongly increased...

Establishment of a low recycling state with full density control by active pumping of the closed helical divertor at LHD

Science.gov (United States)

Motojima, G.; Masuzaki, S.; Tanaka, H.; Morisaki, T.; Sakamoto, R.; Murase, T.; Tsuchibushi, Y.; Kobayashi, M.; Schmitz, O.; Shoji, M.; Tokitani, M.; Yamada, H.; Takeiri, Y.; The LHD Experiment Group

2018-01-01

Superior control of particle recycling and hence full governance of plasma density has been established in the Large Helical Device (LHD) using largely enhanced active pumping of the closed helical divertor (CHD). In-vessel cryo-sorption pumping systems inside the CHD in five out of ten inner toroidal divertor sections have been developed and installed step by step in the LHD. The total effective pumping speed obtained was 67  ±  5 m3 s-1 in hydrogen, which is approximately seven times larger than previously obtained. As a result, a low recycling state was observed with CHD pumping for the first time in LHD featuring excellent density control even under intense pellet fueling conditions. A global particle confinement time (τ p* ) is used for comparison of operation with and without the CHD pumping. The τ p* was evaluated from the density decay after the fueling of hydrogen pellet injection or gas puffing in NBI plasmas. A reliably low base density before the fueling and short τ p* after the fueling were obtained during the CHD pumping, demonstrating for the first time full control of the particle balance with active pumping in the CHD.

Influence of metallurgical and electrochemical factors on cracking of steels at nuclear power plants under high temperature

International Nuclear Information System (INIS)

Pokhmurskii, V.I.; Gnyp, I.P.

1994-01-01

The influence of metallurgical heterogeneities in steels and electrochemical factors on corrosion cracking under high temperature water environment is studied, with special emphasis on the influence of manganese sulfide inclusions and other non-metallic ones on the crack growth rate. Results show that the electro-chemical conditions for an hydrogen concentration increase in a pre-failure zone exist at a crack tip under cyclic loading; hydrogen penetrating into metals at high temperature reduces manganese sulfides, ferric carbides, and cause high pressure of gases in micro-discontinuities, thus leading to cyclic corrosion cracking; anodic (relatively to a metal matrix) inclusions are rather the cause of steel cracking resistance decrease than cathodic ones. 16 refs., 4 figs

Solar-Electrochemical Power System for a Mars Mission

Science.gov (United States)

Withrow, Colleen A.; Morales, Nelson

1994-01-01

This report documents a sizing study of a variety of solar electrochemical power systems for the intercenter NASA study known as 'Mars Exploration Reference Mission'. Power systems are characterized for a variety of rovers, habitation modules, and space transport vehicles based on requirements derived from the reference mission. The mission features a six-person crew living on Mars for 500 days. Mission power requirements range from 4 kWe to 120 kWe. Primary hydrogen and oxygen fuel cells, regenerative hydrogen and oxygen fuel cells, sodium sulfur batteries advanced photovoltaic solar arrays of gallium arsenide on germanium with tracking and nontracking mechanisms, and tent solar arrays of gallium arsenide on germanium are evaluated and compared.

Electrodeposited synthesis of self-supported Ni-P cathode for efficient electrocatalytic hydrogen generation

Directory of Open Access Journals (Sweden)

Ruixian Wu

2016-06-01

Full Text Available One of the key challenges for electrochemical water splitting is the development of low-cost and efficient hydrogen evolution cathode. In this work, a self-supported Ni-P cathode was synthesized by a facile electrodeposition method. The composition and morphology were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy. The Ni-P cathode performed low onset over-potential, good catalytic activity and long-term stability under neutral and alkaline conditions. The mechanism of Ni-P electrode for hydrogen production was discussed by electrochemical impedance spectroscopy. The excellent performance of Ni-P cathode was mainly attributed to the synergistic effect of phosphate anions and the self-supported feature.

In situ hydrogenation of molybdenum oxide nanowires for enhanced supercapacitors

KAUST Repository

Shakir, Imran

2014-01-01

In situ hydrogenation of orthorhombic molybdenum trioxide (α-MoO 3) nanowires has been achieved on a large scale by introducing alcohol during the hydrothermal synthesis for electrochemical energy storage supercapacitor devices. The hydrogenated molybdenum trioxide (H xMoO3) nanowires yield a specific capacitance of 168 F g-1 at 0.5 A g-1 and maintain 108 F g-1 at 10 A g-1, which is 36-fold higher than the capacitance obtained from pristine MoO3 nanowires at the same conditions. The electrochemical devices made with HxMoO3 nanowires exhibit excellent cycling stability by retaining 97% of their capacitance after 3000 cycles due to an enhanced electronic conductivity and increased density of hydroxyl groups on the surface of the MoO3 nanowires. This journal is © The Royal Society of Chemistry.

Small-sized pump for the target chamber of the E-SUVI accelerator

International Nuclear Information System (INIS)

Borts, B.V.; Kravchenko, S.F.; Pisarev, G.V.; Rubashko, V.G.; Khorenko, V.K.

1980-01-01

The target chamber of the accelerator ESUVI is located at the high voltage end of the accelerating tube under the electrostatic generator conductor. The pumping out from the target chamber region has been performed through the accelerating tube its rate constituting 1.5 l/s which resulted in oxidation and contamination of the surface of irradiated targets in the course of the irradiation of chemically active materials. For obtaining high vacuum in a target chamber a small-size gettering-ionic pump of the ORBITRON type has been developed which operates in the autonomous mode. The pump pumping out rate in the pressure range 10 -5 -10 -7 mm Hg constitutes for air and nitrogen 20-25 l/s, ffor oxygen 30-40 l/s, for hydrogen 100-120 l/s. The pump weight without supply units is 2 kg. The pumps permits performing pressure indicator in the target chamber. Using the developed pump makes possible to decrease the target chamber pressure to 1x10 -6 mm Hg for active gases to 10 -8 -10 -9 mm Hg

Gas-permeable hydrophobic tubular membranes for ammonia recovery in bio-electrochemical systems

NARCIS (Netherlands)

Kuntke, P.; Zamora, P.; Saakes, M.; Buisman, C.J.N.; Hamelers, H.V.M.

2016-01-01

The application of a gas-permeable hydrophobic tubular membrane in bio-electrochemical systems enables efficient recovery of ammonia (NH₃) from their cathode compartments. Due to a hydrogen evolution reaction at the cathode, no chemical addition was required to increase the pH for

Pumps and pump facilities. 2. ed.

International Nuclear Information System (INIS)

Bohl, W.; Bauerfeind, H.; Gutmann, G.; Leuschner, G.; Matthias, H.B.; Mengele, R.; Neumaier, R.; Vetter, G.; Wagner, W.

1981-01-01

This book deals with the common fundamental aspects of liquid pumps and gives an exemplary choice of the most important kinds of pumps. The scientific matter is dealt with by means of practical mathematical examples among other ways of presenting the matter. Survey of contents: Division on main operational data of pumps - pipe characteristics - pump characteristics - suction behaviour of the pumps - projecting and operation of rotary pumps - boiler feed pumps - reactor feed pumps - oscillating positive-displacement pumps - eccentric spiral pumps. (orig./GL) [de

Role of hydrogen in future North European power system in 2060

DEFF Research Database (Denmark)

Meibom, Peter; Karlsson, Kenneth Bernard

2010-01-01

the heat production in heat pumps and electric heat boilers, and by varying the production of hydrogen in electrolysis plants in combination with hydrogen storage. Investment in hydrogen storage capacity corresponded to 1.2% of annual wind power production in the scenarios without a hydrogen demand from...... the future success of fuel cell technologies have been investigated as well as different electricity and heat demand assumptions. The variability of wind power production was handled by varying the hydropower production and the production on CHP plants using biomass, by power transmission, by varying...

Meso-microstructural computational simulation of the hydrogen permeation test to calculate intergranular, grain boundary and effective diffusivities

Energy Technology Data Exchange (ETDEWEB)

Jothi, S., E-mail: s.jothi@swansea.ac.uk [College of Engineering, Swansea University, Singleton Park, Swansea SA2 8PP (United Kingdom); Winzer, N. [Fraunhofer Institute for Mechanics of Materials IWM, Wöhlerstraße 11, 79108 Freiburg (Germany); Croft, T.N.; Brown, S.G.R. [College of Engineering, Swansea University, Singleton Park, Swansea SA2 8PP (United Kingdom)

2015-10-05

Highlights: • Characterized polycrystalline nickel microstructure using EBSD analysis. • Development meso-microstructural model based on real microstructure. • Calculated effective diffusivity using experimental electrochemical permeation test. • Calculated intergranular diffusivity of hydrogen using computational FE simulation. • Validated the calculated computation simulation results with experimental results. - Abstract: Hydrogen induced intergranular embrittlement has been identified as a cause of failure of aerospace components such as combustion chambers made from electrodeposited polycrystalline nickel. Accurate computational analysis of this process requires knowledge of the differential in hydrogen transport in the intergranular and intragranular regions. The effective diffusion coefficient of hydrogen may be measured experimentally, though experimental measurement of the intergranular grain boundary diffusion coefficient of hydrogen requires significant effort. Therefore an approach to calculate the intergranular GB hydrogen diffusivity using finite element analysis was developed. The effective diffusivity of hydrogen in polycrystalline nickel was measured using electrochemical permeation tests. Data from electron backscatter diffraction measurements were used to construct microstructural representative volume elements including details of grain size and shape and volume fraction of grains and grain boundaries. A Python optimization code has been developed for the ABAQUS environment to calculate the unknown grain boundary diffusivity.

Hydrogen fuel - Universal energy

Science.gov (United States)

Prince, A. G.; Burg, J. A.

The technology for the production, storage, transmission, and consumption of hydrogen as a fuel is surveyed, with the physical and chemical properties of hydrogen examined as they affect its use as a fuel. Sources of hydrogen production are described including synthesis from coal or natural gas, biomass conversion, thermochemical decomposition of water, and electrolysis of water, of these only electrolysis is considered economicially and technologically feasible in the near future. Methods of production of the large quantities of electricity required for the electrolysis of sea water are explored: fossil fuels, hydroelectric plants, nuclear fission, solar energy, wind power, geothermal energy, tidal power, wave motion, electrochemical concentration cells, and finally ocean thermal energy conversion (OTEC). The wind power and OTEC are considered in detail as the most feasible approaches. Techniques for transmission (by railcar or pipeline), storage (as liquid in underwater or underground tanks, as granular metal hydride, or as cryogenic liquid), and consumption (in fuel cells in conventional power plants, for home usage, for industrial furnaces, and for cars and aircraft) are analyzed. The safety problems of hydrogen as a universal fuel are discussed, noting that they are no greater than those for conventional fuels.

Integrating Microbial Electrochemical Technology with Forward Osmosis and Membrane Bioreactors: Low-Energy Wastewater Treatment, Energy Recovery and Water Reuse

KAUST Repository

Werner, Craig M.

2014-06-01

Wastewater treatment is energy intensive, with modern wastewater treatment processes consuming 0.6 kWh/m3 of water treated, half of which is required for aeration. Considering that wastewater contains approximately 2 kWh/m3 of energy and represents a reliable alternative water resource, capturing part of this energy and reclaiming the water would offset or even eliminate energy requirements for wastewater treatment and provide a means to augment traditional water supplies. Microbial electrochemical technology is a novel technology platform that uses bacteria capable of producing an electric current outside of the cell to recover energy from wastewater. These bacteria do not require oxygen to respire but instead use an insoluble electrode as their terminal electron acceptor. Two types of microbial electrochemical technologies were investigated in this dissertation: 1) a microbial fuel cell that produces electricity; and 2) a microbial electrolysis cell that produces hydrogen with the addition of external power. On their own, microbial electrochemical technologies do not achieve sufficiently high treatment levels. Innovative approaches that integrate microbial electrochemical technologies with emerging and established membrane-based treatment processes may improve the overall extent of wastewater treatment and reclaim treated water. Forward osmosis is an emerging low-energy membrane-based technology for seawater desalination. In forward osmosis water is transported across a semipermeable membrane driven by an osmotic gradient. The microbial osmotic fuel cell described in this dissertation integrates a microbial fuel cell with forward osmosis to achieve wastewater treatment, energy recovery and partial desalination. This system required no aeration and generated more power than conventional microbial fuel cells using ion exchange membranes by minimizing electrochemical losses. Membrane bioreactors incorporate semipermeable membranes within a biological wastewater

High voltage AC/AC electrochemical capacitor operating at low temperature in salt aqueous electrolyte

Science.gov (United States)

Abbas, Qamar; Béguin, François

2016-06-01

We demonstrate that an activated carbon (AC)-based electrochemical capacitor implementing aqueous lithium sulfate electrolyte in 7:3 vol:vol water/methanol mixture can operate down to -40 °C with good electrochemical performance. Three-electrode cell investigations show that the faradaic contributions related with hydrogen chemisorption in the negative AC electrode are thermodynamically unfavored at -40 °C, enabling the system to work as a typical electrical double-layer (EDL) capacitor. After prolonged floating of the AC/AC capacitor at 1.6 V and -40°C, the capacitance, equivalent series resistance and efficiency remain constant, demonstrating the absence of ageing related with side redox reactions at this temperature. Interestingly, when temperature is increased back to 24 °C, the redox behavior due to hydrogen storage reappears and the system behaves as a freshly prepared one.

Uniform manganese hexacyanoferrate hydrate nanocubes featuring superior performance for low-cost supercapacitors and nonenzymatic electrochemical sensors

Science.gov (United States)

Pang, Huan; Zhang, Yizhou; Cheng, Tao; Lai, Wen-Yong; Huang, Wei

2015-09-01

Uniform manganese hexacyanoferrate hydrate nanocubes are prepared via a simple chemical precipitation method at room temperature. Due to both micro/mesopores of the Prussian blue analogue and nanocubic structures, the manganese hexacyanoferrate hydrate nanocubes allow the efficient charge transfer and mass transport for electrolyte solution and chemical species. Thus, the manganese hexacyanoferrate hydrate nanocube electrode shows a good rate capability and cycling stability for electrochemical capacitors. Furthermore, electrodes modified with manganese hexacyanoferrate hydrate nanocubes demonstrate a sensitive electrochemical response to hydrogen peroxide (H2O2) in buffer solutions with a high selectivity.Uniform manganese hexacyanoferrate hydrate nanocubes are prepared via a simple chemical precipitation method at room temperature. Due to both micro/mesopores of the Prussian blue analogue and nanocubic structures, the manganese hexacyanoferrate hydrate nanocubes allow the efficient charge transfer and mass transport for electrolyte solution and chemical species. Thus, the manganese hexacyanoferrate hydrate nanocube electrode shows a good rate capability and cycling stability for electrochemical capacitors. Furthermore, electrodes modified with manganese hexacyanoferrate hydrate nanocubes demonstrate a sensitive electrochemical response to hydrogen peroxide (H2O2) in buffer solutions with a high selectivity. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04322k

Complex Metal Hydrides for Hydrogen, Thermal and Electrochemical Energy Storage

DEFF Research Database (Denmark)

Moller, Kasper T.; Sheppard, Drew; Ravnsbaek, Dorthe B.

2017-01-01

Hydrogen has a very diverse chemistry and reacts with most other elements to form compounds, which have fascinating structures, compositions and properties. Complex metal hydrides are a rapidly expanding class of materials, approaching multi-functionality, in particular within the energy storage...... inspiration to solve the great challenge of our time: efficient conversion and large-scale storage of renewable energy....... field. This review illustrates that complex metal hydrides may store hydrogen in the solid state, act as novel battery materials, both as electrolytes and electrode materials, or store solar heat in a more efficient manner as compared to traditional heat storage materials. Furthermore, it is highlighted...

Laser-driven polarized sources of hydrogen and deuterium

International Nuclear Information System (INIS)

Young, L.; Holt, R.J.; Green, M.C.; Kowalczyk, R.S.

1988-01-01

A novel laser-driven polarized source of hydrogen and deuterium which operates on the principle of spin exchange optical pumping is described. The advantages of this method over conventional polarized sources for internal target experiments are presented. Technological difficulties which prevent ideal source operation are outlined along with proposed solutions. At present, the laser-driven polarized hydrogen source delivers 8 /times/ 10 16 atoms/s with a polarization (P/sub z/) of 24%. 9 refs., 2 figs

Modified porous silicon for electrochemical sensor of para-nitrophenol

Energy Technology Data Exchange (ETDEWEB)

Belhousse, S., E-mail: all_samia_b@yahoo.fr [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE), Division Thin Films-Surface and Interface, 2, Bd. Frantz Fanon, B.P. 140, Alger-7 merveilles, Algiers (Algeria); Belhaneche-Bensemra, N., E-mail: nbelhaneche@yahoo.fr [Ecole Nationale Polytechnique (ENP), 10, Avenue Hassen Badi, B.P. 182, 16200, El Harrach, Algiers (Algeria); Lasmi, K., E-mail: kahinalasmi@yahoo.fr [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE), Division Thin Films-Surface and Interface, 2, Bd. Frantz Fanon, B.P. 140, Alger-7 merveilles, Algiers (Algeria); Mezaache, I., E-mail: lyeso_44@hotmail.fr [Ecole Nationale Polytechnique (ENP), 10, Avenue Hassen Badi, B.P. 182, 16200, El Harrach, Algiers (Algeria); Sedrati, T., E-mail: tarek_1990m@hotmail.fr [Ecole Nationale Polytechnique (ENP), 10, Avenue Hassen Badi, B.P. 182, 16200, El Harrach, Algiers (Algeria); Sam, S., E-mail: Sabrina.sam@polytechnique.edu [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE), Division Thin Films-Surface and Interface, 2, Bd. Frantz Fanon, B.P. 140, Alger-7 merveilles, Algiers (Algeria); Tighilt, F.-Z., E-mail: mli_zola@yahoo.fr [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE), Division Thin Films-Surface and Interface, 2, Bd. Frantz Fanon, B.P. 140, Alger-7 merveilles, Algiers (Algeria); Gabouze, N., E-mail: ngabouze@yahoo.fr [Centre de Recherche en Technologie des Semi-conducteurs pour l’Energétique (CRTSE), Division Thin Films-Surface and Interface, 2, Bd. Frantz Fanon, B.P. 140, Alger-7 merveilles, Algiers (Algeria)

2014-11-15

Highlights: • Hybrid device based on Porous silicon (PSi) and polythiophene (PTh) was prepared. • Three types of PSi/PTh hybrid structures were elaborated: PSi/PTh, oxide/PSi/PTh and Amino-propyltrimethoxysilane (APTMES)/oxide/PSi/PTh. • PTh was grafted on PSi using electrochemical polymerization. • The electrodetection of para-nitrophenol (p-NPh) was performed by cyclic voltammetry. • Oxide/PSi/PTh and APTMES/oxide/PSi/PTh, based electrochemical sensor showed a good response toward p-NPh. - Abstract: Hybrid structures based on polythiophene modified porous silicon was used for the electrochemical detection of para-nitrophenol, which is a toxic derivative of parathion insecticide and it is considered as a major toxic pollutant. The porous silicon was prepared by anodic etching in hydrofluodic acid. Polythiophene films were then grown by electropolymerisation of thiophene monomer on three different surfaces: hydrogenated PSi, oxidized PSi and amine-terminated PSi. The morphology of the obtained structures were observed by scanning electron microscopy and characterized by spectroscopy (FTIR). Cyclic voltammetry was used to study the electrochemical response of proposed structures to para-nitrophenol. The results show a high sensitivity of the sensor and a linearity of the electrochemical response in a large concentration interval ranging from 1.5 × 10{sup −8} M to the 3 × 10{sup −4}M.

Hydrogen energy - Abundant, efficient, clean: A debate over the energy-system-of-change

Energy Technology Data Exchange (ETDEWEB)

Winter, Carl-Jochen [International Association for Hydrogen Energy (IAHE), c/o ENERGON Carl-Jochen Winter e.K., Obere St.-Leonhardstr. 9, 88662 Ueberlingen (Germany)

2009-07-15

Both secondary energies, electricity and hydrogen, have much in common: they are technology driven; both are produced from any available primary energy; once produced both are environmentally and climatically clean over the entire length of their respective conversion chains, from production to utilization; they are electrochemically interchangeable via electrolyses and fuel cells; both rely on each other, e.g., when electrolyzers and liquefiers need electricity or when electricity-providing low temperature fuel cells need hydrogen; in cases of secondary energy transport over longer distances they compete with each other; in combined fossil fuel cycles both hydrogen and electricity are produced in parallel exergetically highly efficiently; hydrogen in addition to electricity helps exergizing the energy system and, thus, maximizing the available technical work. There are dissimilarities, too: electricity transports information, hydrogen does not; hydrogen stores and transports energy, electricity does not (in macroeconomic terms). The most obvious dissimilarity is their market presence, both in capacities and in availability: Electricity is globally ubiquitous (almost), whilst hydrogen energy is still used in only selected industrial areas and in much smaller capacities. The article describes in 15 chapters, 33 figures, 3 tables, and 2 Annexes the up-and-coming hydrogen energy economy, its environmental and climatic relevance, its exergizing influence on the energy system, its effect on decarbonizing fossil fueled power plants, the introduction of the novel non-heat-engine-related electrochemical energy converter fuel cell in portable electronics, in stationary and mobile applications. Hydrogen guarantees environmentally and climatically clean transportation on land, in air and space, and at sea. Hydrogen facilitates the electrification of vehicles with practically no range limits. (author)

Dye-Sensitized Photocatalytic Water Splitting and Sacrificial Hydrogen Generation: Current Status and Future Prospects

Directory of Open Access Journals (Sweden)

Pankaj Chowdhury

2017-05-01

Full Text Available Today, global warming and green energy are important topics of discussion for every intellectual gathering all over the world. The only sustainable solution to these problems is the use of solar energy and storing it as hydrogen fuel. Photocatalytic and photo-electrochemical water splitting and sacrificial hydrogen generation show a promise for future energy generation from renewable water and sunlight. This article mainly reviews the current research progress on photocatalytic and photo-electrochemical systems focusing on dye-sensitized overall water splitting and sacrificial hydrogen generation. An overview of significant parameters including dyes, sacrificial agents, modified photocatalysts and co-catalysts are provided. Also, the significance of statistical analysis as an effective tool for a systematic investigation of the effects of different factors and their interactions are explained. Finally, different photocatalytic reactor configurations that are currently in use for water splitting application in laboratory and large scale are discussed.

Facile Synthesis of Boron-doped Graphene Nanosheets with Hierarchical Microstructure at Atmosphere Pressure for Metal-free Electrochemical Detection of Hydrogen Peroxide

International Nuclear Information System (INIS)

Yeh, Min-Hsin; Li, Yan-Sheng; Chen, Guan-Lin; Lin, Lu-Yin; Li, Ta-Jen; Chuang, Hui-Min; Hsieh, Cheng-Yu; Lo, Shen-Chuan; Chiang, Wei-Hung; Ho, Kuo-Chuan

2015-01-01

Graphical abstract: Display Omitted -- Highlights: • B-doped graphene nanosheets (BGNs) were used as a catalyst for sensing H 2 O 2 . • BGNs were synthesized by an atmospheric-pressure carbothermal reaction. • BGNs with hierarchical microstructure provide more electron transport pathways. • B atoms act as the active sites by transferring charges to neighboring C atoms. • Electrocatalytic ability of BGNs was characterized by a rotating disk electrode. -- Abstract: Hydrogen peroxide (H 2 O 2 ) is an essential mediator for most of the oxidative biological reactions in enzyme-based biosensor systems, such as glucose oxidase, cholesterol oxidase, and alcohol oxidase. Synthesis of new catalysts to detect the concentration of H 2 O 2 more precisely is indispensable for enzyme-based electrochemical biosensors. In this study, boron-doped graphene nanosheets (BGNs) with 2.2 atomic percentage (at%) boron doping level and a hierarchical microstructure were synthesized by an atmospheric-pressure carbothermal reaction as a noble-metal free catalyst for sensing H 2 O 2 . The isolated boron atoms on the BGNs surface act as the electrocatalytic sites by transferring charges to neighbor carbon atoms, and the hierarchical microstructure provides multidimensional electron transport pathways for charge transfer and therefore enhances the electrocatalytic ability. BGNs possess a higher reduction current in the cyclic voltammetry (CV) measurement than that of pristine graphene nanosheets (GNs) over the detection range of 0.0 to 10.0 mM at −0.4 V (vs. Ag/AgCl). The BGNs modified electrochemical sensor shows a linear range from 1.0 to 20.0 mM of H 2 O 2 with a sensitivity of 266.7 ± 3.8 μA mM −1 cm −2 and limit of detection (LOD) of 3.8 μM at a signal-to-noise (S/N) ratio of 3. The beneficial hierarchical microstructure and the synergetic effects arising from doping boron in GNs accomplish the better performance of the BGNs modified electrochemical sensor

Hydrogen production from nano-porous Si powder formed by stain etching

Energy Technology Data Exchange (ETDEWEB)

Litvinenko, S.; Alekseev, S.; Kuznetsov, G.; Skryshevsky, V. [Institute of High Technology of National Taras Shevchenko University of Kyiv, Volodymyrs' ka 64, Kyiv 01601 (Ukraine); Lysenko, V.; Barbier, D. [Lyon Institute of Nanotechnologies (INL), CNRS UMR-5270, University of Lyon, INSA de Lyon, 7 avenue Jean Capelle, Bat. Blaise Pascal, 69621 Villeurbanne Cedex (France); Venturello, A.; Geobaldo, F.; Garrone, E. [Politecnico di Torino, Department of Materials Science and Chemical Engineering, 10129 Torino (Italy); Gulina, L.; Tolstoy, V. [St-Petersburg State University, Chemical Department (Russian Federation)

2010-07-15

Hydrogen reservoirs based on porous silicon (PS) nanostructures are considered. Silicon-based hydrogen tanks are believed to be applicable for portable device energy supply and compatible with micro-sources of energy of new generation. Stain etching of silicon powder to produce PS is studied as a technology alternative to conventional electrochemical etching and application of the PS powder for hydrogen production is also described. Size selection of initial Si micro-particles constituting the powders was carried out by sedimentation technique. Hydrogen content in PS was investigated by FTIR spectroscopy. Extraction of hydrogen in water environment in presence of small amount of NH{sub 3} as catalyst was shown to have advantages such as safety and tunability, additional production of hydrogen from water dissociation, and a possibility to characterize PS as a hydrogen source material in terms of hydrogen effective shell and crystalline core conception. (author)

Influence of metallurgical heterogeneities on the mechanisms of hydrogen diffusion and trapping of in nickel

International Nuclear Information System (INIS)

Oudriss, Abdelali

2012-01-01

A thorough investigation on the influence of several metallurgical defects on the hydrogen diffusion and trapping was conducted on nickel. This work was conducted towards two scientific orientations. A first approach was to assess the impact of intrinsic defects, especially grain boundaries and geometrically necessary dislocations on the hydrogen transport and segregation mechanisms. Combining microstructural characterizations with electrochemical permeation tests and thermal desorption spectroscopy, it has established that the grain boundaries with ordered structure called 'special grain boundaries' are preferential areas for hydrogen segregation. On the other hand, a second category of grain boundaries called 'general' or 'random' with high free volume and disordered structure are promoters for hydrogen diffusion, and they represent the main sources of the phenomena short circuit diffusion reported in the face-centered cubic materials. The second approach of this work consisted in the study of the interaction of hydrogen with the plastic deformation heterogeneities. The electrochemical permeation tests performed on microstructures obtained by deformation showed that for the traction monotonous, the equiaxed cells and walls of dislocations are the potential traps for hydrogen and they slow its transport, this latter is mainly provided by the interstitial diffusion mechanism. In addition, for fatigue microstructure, rapid diffusivity of hydrogen was recorded, and suggesting that a phenomenon similar to short-circuit diffusion is involved in the transport of hydrogen. On two approaches, the results suggest a contribution of hydrogen in the formation of vacancies. (author) [fr

Electrochemical titration of hydrogen adsorbed on supported platinum catalysts

Czech Academy of Sciences Publication Activity Database

Paseka, Ivo

2007-01-01

Roč. 329, - (2007), s. 161-163 ISSN 0926-860X R&D Projects: GA ČR GA104/03/0409 Institutional research plan: CEZ:AV0Z40320502 Keywords : platinum * hydrogen adsorption * specific surface area Subject RIV: CA - Inorganic Chemistry Impact factor: 3.166, year: 2007

Hydrogen anode for nitrate waste destruction. Revision 2

International Nuclear Information System (INIS)

Hobbs, D.T.; Kalu, E.E.; White, R.E.

1996-01-01

Large quantities of radioactive and hazardous wastes have been generated from nuclear materials production during the past fifty years. Processes are under evaluation to separate the high level radioactive species from the waste and store them permanently in the form of durable solids. The schemes proposed will separate the high level radioactive components, cesium-137 and strontium-90, into a small volume for incorporation into a glass wasteform. The remaining low-level radioactive waste contain species such as nitrites and nitrates that are capable of contaminating ground water. Electrochemical destruction of the nitrate and nitrite before permanent storage has been proposed. Not only will the electrochemical processing destroy these species, the volume of the waste could also be reduced. The use of a hydrogen gas-fed anode and an acid anolyte in an electrochemical cell used to destroy nitrate was demonstrated. A mixed Na 2 SO 4 /H 2 SO 4 anolyte was shown to favor the nitrate cell performance, and the generation of a higher hydroxide ion concentration in the catholyte. The suggested scheme is an apparent method of sodium sulfate disposal and a possible means through which ammonia (to ammonium sulfate, fertilizer) and hydrogen gas could be recycled through the anode side of the reactor. This could result in a substantial savings in the operation of a nitrate destruction cell

Layering and Ordering in Electrochemical Double Layers

Energy Technology Data Exchange (ETDEWEB)

Liu, Yihua [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States; Kawaguchi, Tomoya [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States; Pierce, Michael S. [Rochester Institute of Technology, School of Physics and Astronomy, Rochester, New York 14623, United States; Komanicky, Vladimir [Faculty of Science, Safarik University, 041 54 Kosice, Slovakia; You, Hoydoo [Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, United States

2018-02-26

Electrochemical double layers (EDL) form at electrified interfaces. While Gouy-Chapman model describes moderately charged EDL, formation of Stern layers was predicted for highly charged EDL. Our results provide structural evidence for a Stern layer of cations, at potentials close to hydrogen evolution in alkali fluoride and chloride electrolytes. Layering was observed by x-ray crystal truncation rods and atomic-scale recoil responses of Pt(111) surface layers. Ordering in the layer is confirmed by glancing-incidence in-plane diffraction measurements.

Nanosized Magnesium Electrochemically Deposited on a Carbon Nanotubes Suspension: Synthesis and Hydrogen Storage

Energy Technology Data Exchange (ETDEWEB)

Shen, Chaoqi; Aguey-Zinsou, Kondo-Francois, E-mail: f.aguey@unsw.edu.au [MERLin, School of Chemical Engineering, The University of New South Wales, Sydney, NSW (Australia)

2017-10-17

Herein, we report on a novel method for deposition of magnesium (Mg) nanoparticles at the surface of carbon materials. Through the suspension of carbon nanotubes (CNTs) in an electrolyte containing di-n-butylmagnesium as a precursor, Mg nanoparticles were effectively deposited at the surface of the CNTs as soon as these touched the working electrode. Through this process, CNTs supported Mg particles as small as 1 nm were synthesized and the distribution of the nanoparticles was found to be influenced by the concentration of the CNTs in the electrolyte. Hydrogenation of these nanoparticles at 100°C was found to lead to low temperature hydrogen release starting at 150°C, owing to shorter diffusion paths and higher hydrogen mobility in small Mg particles. However, these hydrogen properties drastically degraded as soon as the hydrogenation temperature exceeded 200°C and this may be related to the low melting temperature of ultrasmall Mg particles.

Nanosized Magnesium Electrochemically Deposited on a Carbon Nanotubes Suspension: Synthesis and Hydrogen Storage

Directory of Open Access Journals (Sweden)

Chaoqi Shen

2017-10-01

Full Text Available Herein, we report on a novel method for deposition of magnesium (Mg nanoparticles at the surface of carbon materials. Through the suspension of carbon nanotubes (CNTs in an electrolyte containing di-n-butylmagnesium as a precursor, Mg nanoparticles were effectively deposited at the surface of the CNTs as soon as these touched the working electrode. Through this process, CNTs supported Mg particles as small as 1 nm were synthesized and the distribution of the nanoparticles was found to be influenced by the concentration of the CNTs in the electrolyte. Hydrogenation of these nanoparticles at 100°C was found to lead to low temperature hydrogen release starting at 150°C, owing to shorter diffusion paths and higher hydrogen mobility in small Mg particles. However, these hydrogen properties drastically degraded as soon as the hydrogenation temperature exceeded 200°C and this may be related to the low melting temperature of ultrasmall Mg particles.

The electrochemistry and modelling of hydrogen storage materials

International Nuclear Information System (INIS)

Kalisvaart, W.P.; Vermeulen, P.; Ledovskikh, A.V.; Danilov, D.; Notten, P.H.L.

2007-01-01

Mg-based alloys are promising hydrogen storage materials because of the high gravimetric energy density of MgH 2 (7.6 wt.%). A major disadvantage, however, is its very slow desorption kinetics. It has been argued that, in contrast to the well-known rutile-structured Mg hydride, hydrided Mg-transition metal alloys have a much more open crystal structure facilitating faster hydrogen transport. In this paper, the electrochemical aspects of new Mg-Sc and Mg-Ti materials will be reviewed. Storage capacities as high as 6.5 wt.% hydrogen have been reached with very favourable discharge kinetics. A theoretical description of hydrogen storage materials has also been developed by our group. A new lattice gas model is presented and successfully applied to simulate the thermodynamic properties of various hydride-forming materials. The simulation results are expressed by parameters corresponding to several energy contributions, for example mutual atomic hydrogen interaction energies. A good fit of the lattice gas model to the experimental data is found in all cases

Solubility and diffusivity of hydrogen in enameling steel

Energy Technology Data Exchange (ETDEWEB)

De Gregorio, P.; Valentini, R.; Solina, A.; Gastaldo, F. (Centro Sviluppo Materiali, Rome (Italy) Pisa Univ. (Italy). Dip. di Ingegneria Chimica, Chimica Industriale e Scienza dei Materiali)

1991-06-01

In recent years, continuous casting has almost expelled conventional ingot casting from the steel-making process by its much higher productivity. However, enameling steel sheets doesn't give the steel sufficient resistance to fishscale, as that which is achieved by the inclusions in case of ingot capped steel. Fishscales are caused by hydrogen gas building up pressure at the interface between enamel and steel, resulting in the rupture of enamel. Object of this study, was not only to correlate fishscale susceptibility with metallurgical parameters, but to define the effect of reversible and irreversible traps on hydrogen solubility and diffusivity in enameling steel. Hydrogen permeation was studied, in low carbon enameling steel, with an electrochemical technique developed by Devanathan and co-workers. This method was used to calculate concentrations of irreversibly adsorbed hydrogen and evaluate hydrogen diffusion coefficients. The results on reversible traps correlated with micro-voids formations around the carbide precipitate, while the irreversible traps correlated with inclusions and precipitate content.

Photo-Enhanced Hydrogen Transport Technology for Clean Renewable Electrochemical Energy Systems, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Solid oxide fuel cells and electrolyzers are promising electrochemical devices for space and terrestrial applications due to their high power densities and clean...

Fusion reactor high vacuum pumping

International Nuclear Information System (INIS)

Sedgley, D.W.; Walthers, C.R.; Jenkins, E.M.

1992-01-01

This paper reports on recent experiments which have shown the practicality of using activated carbon (coconut charcoal) at 4K to pump helium and hydrogen isotopes for a fusion reactor. Both speed and capacity for deuterium/helium and tritium/helium-3 mixtures were satisfactory. The long-term effects of tritium on the charcoal/cement system developed by Grumman and LLNL was now known; therefore a program was undertaken to see what, if any, effect long-term tritium exposure has on the cryosorber. Several charcoal on aluminum test samples were subjected to six months exposure of tritium at approximately 77 K. The tritium was scanned several times with a residual gas analyzer and the speed-capacity performance of the samples was measured before, approximately one-third way through, and after the exposure. Modest effects were noted which would not seriously restrict the use of charcoal as a cryosorber for fusion reactor high-vacuum pumping applications

Synchronization modulation increases transepithelial potentials in MDCK monolayers through Na/K pumps.

Directory of Open Access Journals (Sweden)

Vu Tran

Full Text Available Transepithelial potential (TEP is the voltage across a polarized epithelium. In epithelia that have active transport functions, the force for transmembrane flux of an ion is dictated by the electrochemical gradient in which TEP plays an essential role. In epithelial injury, disruption of the epithelial barrier collapses the TEP at the wound edge, resulting in the establishment of an endogenous wound electric field (∼100 mV/mm that is directed towards the center of the wound. This endogenous electric field is implicated to enhance wound healing by guiding cell migration. We thus seek techniques to enhance the TEP, which may increase the wound electric fields and enhance wound healing. We report a novel technique, termed synchronization modulation (SM using a train of electric pulses to synchronize the Na/K pump activity, and then modulating the pumping cycles to increase the efficiency of the Na/K pumps. Kidney epithelial monolayers (MDCK cells maintain a stable TEP and transepithelial resistance (TER. SM significantly increased TEP over four fold. Either ouabain or digoxin, which block Na/K pump, abolished SM-induced TEP increases. In addition to the pump activity, basolateral distribution of Na/K pumps is essential for an increase in TEP. Our study for the first time developed an electrical approach to significantly increase the TEP. This technique targeting the Na/K pump may be used to modulate TEP, and may have implication in wound healing and in diseases where TEP needs to be modulated.

Efficiency of hydrogen gas production in a stand-alone solar hydrogen system

International Nuclear Information System (INIS)

Singh, K.; Tamakloe, R.Y.

2003-01-01

Many photovoltaic systems operate in a decentralised electricity producing system, or stand-alone mode and the total energy demand is met by the output of the photovoltaic array. The output of the photovoltaic system fluctuates and is unpredictable for many applications making some forms of energy storage system necessary. The role of storage medium is to store the excess energy produced by the photovoltaic arry, to absorb momentary power peaks and to supply energy during sunless periods. One of the storage modes is the use of electrochemical techniques, with batteries and water electrolysis as the most important examples. The present study includes three main parts: the first one is the hydrogen production form the electrolysis of water depending on the DC output current of the photovoltaic (PV) energy source and the charging of the battery. The second part presents the influence of various parameters on the efficiency of hydrogen gas production. The final part includes simulation studies with focus on solar hydrogen efficiency under the influence of various physical and chemical parameters. For a 50W panel-battery-electrolyser system, the dependence of volume of hydrogen gas on voltage, current and power yielded a maximum efficiency of 13.6% (author)

Boron-doped Diamond Electrodes: Electrochemical, Atomic Force Microscopy and Raman Study towards Corrosion-modifications at Nanoscale

International Nuclear Information System (INIS)

Kavan, Ladislav; Vlckova Zivcova, Zuzana; Petrak, Vaclav; Frank, Otakar; Janda, Pavel; Tarabkova, Hana; Nesladek, Milos; Mortet, Vincent

2015-01-01

Highlights: • B-doped diamond is nanostructured by corrosion-driven modifications occurring at carbonaceous impurity sites (sp 2 -carbons). • The electrochemical oxidation partly transforms a hydrogen-terminated diamond surface to O-terminated one, but the electrocatalytic activity of plasmatically O-terminated diamond is not achieved. • In contrast to all usual sp 2 carbons, the Raman spectra of B-doped diamond electrodes do not change upon electrochemical charging/discharging. - Abstract: Comparative studies of boron-doped diamonds electrodes (polycrystalline, single-crystalline, H-/O-terminated, and with different sp 3 /sp 2 ratios) indicate morphological modifications of diamond which are initiated by corrosion at nanoscale. In-situ electrochemical AFM imaging evidences that the textural changes start at non-diamond carbonaceous impurity sites treated at high positive potentials (>2.2 V vs. Ag/AgCl). The primary perturbations subsequently develop into sub-micron-sized craters. Raman spectroscopy shows that the primary erosion site is graphite-like (sp 2 -carbon), which is preferentially removed by anodic oxidation. Other non-diamond impurity, viz. tetrahedral amorphous carbon (t-aC), is less sensitive to oxidative decomposition. The diamond-related Raman features, including the B-doping-assigned modes, are intact during reversible electrochemical charging/discharging, which is a salient difference from all usual sp 2 -carbons. The electrochemical oxidation partly transforms a hydrogen-terminated diamond surface to O-terminated one, but the electrocatalytic activity of plasmatically O-terminated diamond is not achieved for a model redox couple, Fe 3+/2+ . Electrochemical impedance spectra were fitted to six different equivalent circuits. The determination of acceptor concentrations is feasible even for highly-doped diamond electrodes.

An investigation on hydrogen storage kinetics of nanocrystalline and amorphous Mg2Ni1-xCox (x = 0-0.4) alloy prepared by melt spinning

International Nuclear Information System (INIS)

Zhang Yanghuan; Li Baowei; Ren Huipin; Ding Xiaoxia; Liu Xiaogang; Chen Lele

2011-01-01

Research highlights: → The investigation of the structures of the Mg 2 Ni 1-x Co x (x = 0, 0.1, 0.2, 0.3, 0.4) alloys indicates that a nanocrystalline and amorphous structure can be obtained in the experiment alloys by melt spinning technology. The substitution of Co for Ni facilitates the glass formation in the Mg 2 Ni-type alloy. And the amorphization degree of the alloys visibly increases with increasing Co content. → Both the melt spinning and Co substitution significantly improve the hydrogen storage kinetics of the alloys. The hydrogen absorption saturation ratio (R t a ) and hydrogen desorption ratio (R t d ) as well as the high rate discharge ability (HRD) increase with rising spinning rate and Co content. The hydrogen diffusion coefficient (D), the Tafel polarization curves and the electrochemical impedance spectra (EIS) measurements show that the electrochemical kinetics notably increases with rising spinning rate and Co content. → Furthermore, all the as-spun alloys, when the spinning rate reaches to 30 m/s, have nearly same hydrogen absorption kinetics, indicating that the hydrogen absorption kinetics of the as-spun alloy is predominately controlled by diffusion ability of hydrogen atoms. - Abstract: In order to improve the hydrogen storage kinetics of the Mg 2 Ni-type alloys, Ni in the alloy was partially substituted by element Co, and melt-spinning technology was used for the preparation of the Mg 2 Ni 1-x Co x (x = 0, 0.1, 0.2, 0.3, 0.4) hydrogen storage alloys. The structures of the as-cast and spun alloys are characterized by XRD, SEM and TEM. The hydrogen absorption and desorption kinetics of the alloys were measured by an automatically controlled Sieverts apparatus. The electrochemical hydrogen storage kinetics of the as-spun alloys is tested by an automatic galvanostatic system. The hydrogen diffusion coefficients in the alloys are calculated by virtue of potential-step method. The electrochemical impedance spectrums (EIS) and the Tafel

Hydrogen absorption in thin ZnO films prepared by pulsed laser deposition

International Nuclear Information System (INIS)

Melikhova, O.; Čížek, J.; Lukáč, F.; Vlček, M.; Novotný, M.; Bulíř, J.; Lančok, J.; Anwand, W.; Brauer, G.; Connolly, J.; McCarthy, E.; Krishnamurthy, S.; Mosnier, J.-P.

2013-01-01

Highlights: ► Thin ZnO films and high quality ZnO crystal were electrochemically doped with hydrogen. ► Hydrogen absorbed in ZnO causes plastic deformation both in ZnO crystal and thin films. ► In ZnO crystal a sub-surface region with very high density of defects was formed. ► Moreover, plastic deformation causes specific surface modification of ZnO crystal. ► In ZnO films hydrogen-induced plastic deformation introduced defects in the whole film. -- Abstract: ZnO films with thickness of ∼80 nm were grown by pulsed laser deposition (PLD) on MgO (1 0 0) single crystal and amorphous fused silica (FS) substrates. Structural studies of ZnO films and a high quality reference ZnO single crystal were performed by slow positron implantation spectroscopy (SPIS). It was found that ZnO films exhibit significantly higher density of defects than the reference ZnO crystal. Moreover, the ZnO film deposited on MgO substrate exhibits higher concentration of defects than the film deposited on amorphous FS substrate most probably due to a dense network of misfit dislocations. The ZnO films and the reference ZnO crystal were subsequently loaded with hydrogen by electrochemical cathodic charging. SPIS characterizations revealed that absorbed hydrogen introduces new defects into ZnO

Hydrogen absorption in thin ZnO films prepared by pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Melikhova, O., E-mail: oksivmel@yahoo.com [Charles University in Prague, Faculty of Mathematics and Physics, V Holesovickach 2, CZ-180 00 Praha 8 (Czech Republic); Čížek, J.; Lukáč, F.; Vlček, M. [Charles University in Prague, Faculty of Mathematics and Physics, V Holesovickach 2, CZ-180 00 Praha 8 (Czech Republic); Novotný, M.; Bulíř, J.; Lančok, J. [Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 182 21 Prague (Czech Republic); Anwand, W.; Brauer, G. [Institut für Strahlenphysik, Helmholtz-Zentrum Dresden-Rossendorf, PO Box 510 119, D-01314 Dresden (Germany); Connolly, J.; McCarthy, E.; Krishnamurthy, S.; Mosnier, J.-P. [National Centre for Plasma Science and Technology, School of Physical Sciences, Glasnevin, Dublin 9 (Ireland)

2013-12-15

Highlights: ► Thin ZnO films and high quality ZnO crystal were electrochemically doped with hydrogen. ► Hydrogen absorbed in ZnO causes plastic deformation both in ZnO crystal and thin films. ► In ZnO crystal a sub-surface region with very high density of defects was formed. ► Moreover, plastic deformation causes specific surface modification of ZnO crystal. ► In ZnO films hydrogen-induced plastic deformation introduced defects in the whole film. -- Abstract: ZnO films with thickness of ∼80 nm were grown by pulsed laser deposition (PLD) on MgO (1 0 0) single crystal and amorphous fused silica (FS) substrates. Structural studies of ZnO films and a high quality reference ZnO single crystal were performed by slow positron implantation spectroscopy (SPIS). It was found that ZnO films exhibit significantly higher density of defects than the reference ZnO crystal. Moreover, the ZnO film deposited on MgO substrate exhibits higher concentration of defects than the film deposited on amorphous FS substrate most probably due to a dense network of misfit dislocations. The ZnO films and the reference ZnO crystal were subsequently loaded with hydrogen by electrochemical cathodic charging. SPIS characterizations revealed that absorbed hydrogen introduces new defects into ZnO.

Au/CeO2-chitosan composite film for hydrogen peroxide sensing

International Nuclear Information System (INIS)

Zhang Wei; Xie Guoming; Li Shenfeng; Lu Lingsong; Liu Bei

2012-01-01

Au nanoparticles (AuNPs) were in situ synthesized at the cerium dioxide nanoparticles (CeO 2 NPs)-chitosan (CS) composite film by one-step direct chemical reduction, and the resulting Au/CeO 2 -CS composite were further modified for enzyme immobilization and hydrogen peroxide (H 2 O 2 ) biosensing. Transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), UV-vis spectra and electrochemical techniques have been utilized for characterization of the prepared composite. The stepwise assembly process and electrochemical performances of the biosensor were characterized by means of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and typical amperometric response (i-t). The Au/CeO 2 -CS composite exhibited good conductibility and biocompatibility, and the developed biosensor exhibited excellent response to hydrogen peroxide in the linear range of 0.05-2.5 mM (r = 0.998) with the detection limit of 7 μM (S/N = 3). Moreover, the biosensor presented high affinity (K m app =1.93mM), good reproducibility and storage stability. All these results demonstrate that the Au/CeO 2 -CS composite film can provide a promising biointerface for the biosensor designs and other biological applications.

Electrocatalytic activity mapping of model fuel cell catalyst films using scanning electrochemical microscopy

International Nuclear Information System (INIS)

Nicholson, P.G.; Zhou, S.; Hinds, G.; Wain, A.J.; Turnbull, A.

2009-01-01

Scanning electrochemical microscopy has been employed to spatially map the electrocatalytic activity of model proton exchange membrane fuel cell (PEMFC) catalyst films towards the hydrogen oxidation reaction (the PEMFC anode reaction). The catalyst films were composed of platinum-loaded carbon nanoparticles, similar to those typically used in PEMFCs. The electrochemical characterisation was correlated with a detailed physical characterisation using dynamic light scattering, transmission electron microscopy and field-emission scanning electron microscopy. The nanoparticles were found to be reasonably mono-dispersed, with a tendency to agglomerate into porous bead-type structures when spun-cast. The number of carbon nanoparticles with little or no platinum was surprisingly higher than would be expected based on the platinum-carbon mass ratio. Furthermore, the platinum-rich carbon particles tended to agglomerate and the clusters formed were non-uniformly distributed. This morphology was reflected in a high degree of heterogeneity in the film activity towards the hydrogen oxidation reaction.

Determination of hydrogen in milligram quantities of titanium and its alloys

Science.gov (United States)

Otterson, D. A.; Smith, R. J.

1973-01-01

An accurate, versatile, and sensitive method for the determination of hydrogen in milligram-size titanium samples is presented. It involves extraction of hydrogen at 1070 K while a mercury diffusion pump transfers the evolved gases into the inlet of a mass spectrometer. All the evolved gases may then be positively identified and determined. This method can be readily adapted for use with other metals and for the study of the slow evolution of hydrogen. Reduction of interferences due to the evolution of hydrogen by reactions involving vapors such as those of water, acetone, and vacuum grease is discussed.

Novel Ag@TiO2 nanocomposite synthesized by electrochemically active biofilm for nonenzymatic hydrogen peroxide sensor.

Science.gov (United States)

Khan, Mohammad Mansoob; Ansari, Sajid Ali; Lee, Jintae; Cho, Moo Hwan

2013-12-01

A novel nonenzymatic sensor for H2O2 was developed based on an Ag@TiO2 nanocomposite synthesized using a simple and cost effective approach with an electrochemically active biofilm. The optical, structural, morphological and electrochemical properties of the as-prepared Ag@TiO2 nanocomposite were examined by UV-vis spectroscopy, X-ray diffraction, transmission electron microscopy and cyclic voltammetry (CV). The Ag@TiO2 nanocomposite was fabricated on a glassy carbon electrode (GCE) and their electrochemical performance was analyzed by CV, differential pulse voltammetry and electrochemical impedance spectroscopy. The Ag@TiO2 nanocomposite modified GCE (Ag@TiO2/GCE) displayed excellent performance towards H2O2 sensing at -0.73 V in the linear response range from 0.83 μM to 43.3 μM, within a detection limit and sensitivity of 0.83 μM and ~65.2328±0.01 μA μM(-1) cm(-2), respectively. In addition, Ag@TiO2/GCE exhibited good operational reproducibility and long term stability. © 2013.

Hydrogen production from fusion reactors coupled with high temperature electrolysis

International Nuclear Information System (INIS)

Fillo, J.A.; Powell, J.R.; Steinberg, M.

The decreasing availability of fossil fuels emphasizes the need to develop systems which will produce synthetic fuel to substitute for and complement the natural supply. An important first step in the synthesis of liquid and gaseous fuels is the production of hydrogen. Thermonuclear fusion offers an inexhaustible source of energy for the production of hydrogen from water. Processes which may be considered for this purpose include electrolysis, thermochemical decomposition or thermochemical-electrochemical hybrid cycles. Preliminary studies at Brookhaven indicate that high temperature electrolysis has the highest potential efficiency for production of hydrogen from fusion. Depending on design electric generation efficiencies of approximately 40 to 60 percent and hydrogen production efficiencies of approximately 50 to 70 percent are projected for fusion reactors using high temperature blankets

A method for generating hydrogen from water

International Nuclear Information System (INIS)

Godin, Paul; Mascarello, Jean; Millet, Jacques.

1974-01-01

Description is given of a method and an installation for generating hydrogen from water, through an endothermic cycle of several successive chemical reactions involving intermediate substances regenerated during said cycle, said reactions occuring at different temperatures. The reaction which takes place at the highest temperature is carried out electrochemically. This can be applied to power-generating units comprising a nuclear reactor [fr

Solar-mediated thermo-electrochemical oxidation of sodium dodecyl benzene sulfonate by modulating the effective oxidation potential and pathway for green remediation of wastewater

Science.gov (United States)

Gu, Di; Gao, Simeng; Jiang, TingTing; Wang, Baohui

2017-01-01

To match the relentless pursuit of three research hot points - efficient solar utilization, green and sustainable remediation of wastewater and advanced oxidation processes, solar-mediated thermo-electrochemical oxidation of surfactant was proposed and developed for green remediation of surfactant wastewater. The solar thermal electrochemical process (STEP), fully driven with solar energy to electric energy and heat and without an input of other energy, sustainably serves as efficient thermo-electrochemical oxidation of surfactant, exemplified by SDBS, in wastewater with the synergistic production of hydrogen. The electrooxidation-resistant surfactant is thermo-electrochemically oxidized to CO2 while hydrogen gas is generated by lowing effective oxidation potential and suppressing the oxidation activation energy originated from the combination of thermochemical and electrochemical effect. A clear conclusion on the mechanism of SDBS degradation can be proposed and discussed based on the theoretical analysis of electrochemical potential by quantum chemical method and experimental analysis of the CV, TG, GC, FT-IR, UV-vis, Fluorescence spectra and TOC. The degradation data provide a pilot for the treatment of SDBS wastewater that appears to occur via desulfonation followed by aromatic-ring opening. The solar thermal utilization that can initiate the desulfonation and activation of SDBS becomes one key step in the degradation process. PMID:28294180

Surface hardening of Ti-6Al-4V alloy by hydrogenation

International Nuclear Information System (INIS)

Wu, T.I.; Wu, J.K.

1991-01-01

Thermochemical processing is an advanced method to enhance the fabricability and mechanical properties of titanium alloys. In this process hydrogen is added to the titanium alloy as a temporary alloying element. Hydrogen addition lowers the β transus temperature of titanium alloy and stabilizes the β phase. The increased amount of β phase in hydrogen-modified titanium alloys reduces the grain growth rate during eutectoid β → α + hydride reaction. Hydrogen was added to the titanium alloy by holding it at a relatively high temperature in a hydrogen gaseous environment in previous studies. Pattinato reported that Ti-6Al-4V alloy can react with hydrogen gas at ambient temperature and cause a serious hydrogen embrittlement problem. The hydrogen must be removed to a low allowable concentration in a vacuum system after the hydrogenation process. The present study utilized an electrochemical technique to dissolve hydrogen into titanium alloy to replace the hydrogen environment in thermochemical processing. In this paper microstructures and hardnesses of this new processed Ti-6Al-4V alloy are reported

Compact PEM fuel cell system combined with all-in-one hydrogen generator using chemical hydride as a hydrogen source

International Nuclear Information System (INIS)

Kim, Jincheol; Kim, Taegyu

2015-01-01

Highlights: • Compact fuel cell system was developed for a portable power generator. • Novel concept using an all-in-one reactor for hydrogen generation was proposed. • Catalytic reactor, hydrogen chamber and separator were combined in a volume. • The system can be used to drive fuel cell-powered unmanned autonomous systems. - Abstract: Compact fuel cell system was developed for a portable power generator. The power generator features a polymer electrolyte membrane fuel cell (PEMFC) using a chemical hydride as a hydrogen source. The hydrogen generator extracted hydrogen using a catalytic hydrolysis from a sodium borohydride alkaline solution. A novel concept using an all-in-one reactor was proposed in which a catalyst, hydrogen chamber and byproduct separator were combined in a volume. In addition, the reactor as well as a pump, cooling fans, valves and controller was integrated in a single module. A 100 W PEMFC stack was connected with the hydrogen generator and was evaluated at various load conditions. It was verified that the stable hydrogen supply was achieved and the developed system can be used to drive fuel cell-powered unmanned autonomous systems.

Measuring the relative hydrogen-bonding strengths of alcohols in aprotic organic solvents.

Science.gov (United States)

Tessensohn, Malcolm E; Lee, Melvyn; Hirao, Hajime; Webster, Richard D

2015-01-12

Voltammetric experiments with 9,10-anthraquinone and 1,4-benzoquinone performed under controlled moisture conditions indicate that the hydrogen-bond strengths of alcohols in aprotic organic solvents can be differentiated by the electrochemical parameter ΔEp (red) =|Ep (red(1)) -Ep (red(2)) |, which is the potential separation between the two one-electron reduction processes. This electrochemical parameter is inversely related to the strength of the interactions and can be used to differentiate between primary, secondary, tertiary alcohols, and even diols, as it is sensitive to both their steric and electronic properties. The results are highly reproducible across two solvents with substantially different hydrogen-bonding properties (CH3 CN and CH2 Cl2 ) and are supported by density functional theory calculations. This indicates that the numerous solvent-alcohol interactions are less significant than the quinone-alcohol hydrogen-bonding interactions. The utility of ΔEp (red) was illustrated by comparisons between 1) 3,3,3-trifluoro-n-propanol and 1,3-difluoroisopropanol and 2) ethylene glycol and 2,2,2-trifluoroethanol. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photoelectrochemical Hydrogen Production Using New Combinatorial Chemistry Derived Materials

Energy Technology Data Exchange (ETDEWEB)

Jaramillo, Thomas F.; Baeck, Sung-Hyeon; Kleiman-Shwarsctein, Alan; Stucky, Galen D. (PI); McFarland, Eric W. (PI)

2004-10-25

Solar photoelectrochemical water-splitting has long been viewed as one of the “holy grails” of chemistry because of its potential impact as a clean, renewable method of fuel production. Several known photocatalytic semiconductors can be used; however, the fundamental mechanisms of the process remain poorly understood and no known material has the required properties for cost effective hydrogen production. In order to investigate morphological and compositional variations in metal oxides as they relate to opto-electrochemical properties, we have employed a combinatorial methodology using automated, high-throughput, electrochemical synthesis and screening together with conventional solid-state methods. This report discusses a number of novel, high-throughput instruments developed during this project for the expeditious discovery of improved materials for photoelectrochemical hydrogen production. Also described within this report are results from a variety of materials (primarily tungsten oxide, zinc oxide, molybdenum oxide, copper oxide and titanium dioxide) whose properties were modified and improved by either layering, inter-mixing, or doping with one or more transition metals. Furthermore, the morphologies of certain materials were also modified through the use of structure directing agents (SDA) during synthesis to create mesostructures (features 2-50 nm) that increased surface area and improved rates of hydrogen production.

The electrochemical fluorination of polymeric materials for high energy density aqueous and non-aqueous battery and fuel cell separators

Science.gov (United States)

Liu, C. C.

1983-01-01

A computerized system was established and the electrochemical fluorination of trichloroethylene, polyacrylic acid and polyvinyl alcohol in anhydrous hydrogen fluoride was attempted. Both solid substrates as well as membranes were used. Some difficulties were found in handling and analyzing the solid substrates and membranes. Further studies are needed in this area. A microprocessor aided electrochemical fluorination system capable of obtaining highly reproducible experimental results was established.

System design description for SY-101 hydrogen mitigation test project data acquisition and control system (DACS-1)

International Nuclear Information System (INIS)

Truitt, R.W.; Pounds, T.S.; Smith, S.O.

1994-01-01

This document describes the hardware subsystems of the data acquisition and control system (DACS) used in mitigation tests conducted on waste tank SY-101 at the Hanford Nuclear Reservation. The system was designed and implemented by Los Alamos National Laboratory (LANL) and supplied to Westinghouse Hanford Company (WHC). The mitigation testing uses a pump immersed in the waste tank, directed at certain angles and operated at different speeds and time durations. The SY-101 tank has experienced recurrent periodic gas releases of hydrogen, nitrous oxide, ammonia, and (recently discovered) methane. The hydrogen gas represents a danger, as some of the releases are in amounts above the lower flammability limit (LFL). These large gas releases must be mitigated. Several instruments have been added to the tank to monitor the gas compositions, the tank level, the tank temperature, and other parameters. A mixer pump has been developed to stir the tank waste to cause the gases to be released at a slow rate. It is the function of the DACS to monitor those instruments and to control the mixer pump in a safe manner. During FY93 and FY94 the mixer pump was installed with associated testing operations support equipment and a mitigation test project plan was implemented. These activities successfully demonstrated the mixer pump's ability to mitigate the SY-101 tank hydrogen gas hazard

Turning a Poor Ion Channel into a Good Pump

Science.gov (United States)

Astumian, Dean

2003-05-01

We consider a membrane protein that can exist in two configurations, either one of which acts as a poor ion channel, allowing ions to slowly leak across the membrane from high to low elctrochemical potential. We show that random external fluctuations can provide the energy to turn this poor channel into a good pump that drives ion transport from low to high electrochemical potential. We discuss this result in terms of a gambling analogy, and point to possible implications for fields as far ranging as population biology, economics, and actuarial science.

Pumping behavior of sputter ion pumps

International Nuclear Information System (INIS)

Chou, T.S.; McCafferty, D.

The ultrahigh vacuum requirements of ISABELLE is obtained by distributed pumping stations. Each pumping station consists of 1000 l/s titanium sublimation pump for active gases (N 2 , H 2 , O 2 , CO, etc.), and a 20 l/s sputter ion pump for inert gases (methane, noble gases like He, etc.). The combination of the alarming production rate of methane from titanium sublimation pumps (TSP) and the decreasing pumping speed of sputter ion pumps (SIP) in the ultrahigh vacuum region (UHV) leads us to investigate this problem. In this paper, we first describe the essential physics and chemistry of the SIP in a very clean condition, followed by a discussion of our measuring techniques. Finally measured methane, argon and helium pumping speeds are presented for three different ion pumps in the range of 10 -6 to 10 -11 Torr. The virtues of the best pump are also discussed

Hydrogen Fueling Station Using Thermal Compression: a techno-economic analysis

Energy Technology Data Exchange (ETDEWEB)

Kriha, Kenneth [Gas Technology Inst., Des Plaines, IL (United States); Petitpas, Guillaume [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Melchionda, Michael [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Soto, Herie [Shell, Houston TX (United States); Feng, Zhili [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wang, Yanli [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2017-08-11

The goal of this project was to demonstrate the technical and economic feasibility of using thermal compression to create the hydrogen pressure necessary to operate vehicle hydrogen fueling stations. The concept of utilizing the exergy within liquid hydrogen to build pressure rather than mechanical components such as compressors or cryogenic liquid pumps has several advantages. In theory, the compressor-less hydrogen station will have lower operating and maintenance costs because the compressors found in conventional stations require large amounts of electricity to run and are prone to mechanical breakdowns. The thermal compression station also utilizes some of the energy used to liquefy the hydrogen as work to build pressure, this is energy that in conventional stations is lost as heat to the environment.

Synthesis and utilization of carbon nanotubes for fabrication of electrochemical biosensors

International Nuclear Information System (INIS)

Lawal, Abdulazeez T.

2016-01-01

Graphical abstract: Carbon nanotubes. - Highlights: • This review discusses synthesis and applications of carbon nanotubes sensors. • The review summarizes contributions of carbon nanotube to electrochemical biosensor. • Good electrical conductivity makes carbon nanotubes a good material for biosensors. • Carbon nanotubes promotes electron transfer that aids biosensing of biomolecules. - Abstract: This review summarizes the most recent contributions in the fabrication of carbon nanotubes-based electrochemical biosensors in recent years. It discusses the synthesis and application of carbon nanotubes to the assembly of carbon nanotube-based electrochemical sensors, its analytical performance and future expectations. An increasing number of reviews and publications involving carbon nanotubes sensors have been reported ever since the first design of carbon nanotube electrochemical biosensors. The large surface area and good electrical conductivity of carbon nanotubes allow them to act as “electron wire” between the redox center of an enzyme or protein and an electrode's surface, which make them very excellent material for the design of electrochemical biosensors. Carbon nanotubes promote the different rapid electron transfers that facilitate accurate and selective detection of cytochrome-c, β-nicotinamide adenine dinucleotide, hemoglobin and biomolecules, such as glucose, cholesterol, ascorbic acid, uric acid, dopamine pesticides, metals ions and hydrogen peroxide.

Synthesis and utilization of carbon nanotubes for fabrication of electrochemical biosensors

Energy Technology Data Exchange (ETDEWEB)

Lawal, Abdulazeez T., E-mail: abdul.lawal@yahoo.com

2016-01-15

Graphical abstract: Carbon nanotubes. - Highlights: • This review discusses synthesis and applications of carbon nanotubes sensors. • The review summarizes contributions of carbon nanotube to electrochemical biosensor. • Good electrical conductivity makes carbon nanotubes a good material for biosensors. • Carbon nanotubes promotes electron transfer that aids biosensing of biomolecules. - Abstract: This review summarizes the most recent contributions in the fabrication of carbon nanotubes-based electrochemical biosensors in recent years. It discusses the synthesis and application of carbon nanotubes to the assembly of carbon nanotube-based electrochemical sensors, its analytical performance and future expectations. An increasing number of reviews and publications involving carbon nanotubes sensors have been reported ever since the first design of carbon nanotube electrochemical biosensors. The large surface area and good electrical conductivity of carbon nanotubes allow them to act as “electron wire” between the redox center of an enzyme or protein and an electrode's surface, which make them very excellent material for the design of electrochemical biosensors. Carbon nanotubes promote the different rapid electron transfers that facilitate accurate and selective detection of cytochrome-c, β-nicotinamide adenine dinucleotide, hemoglobin and biomolecules, such as glucose, cholesterol, ascorbic acid, uric acid, dopamine pesticides, metals ions and hydrogen peroxide.

Nanodevices in nature: Electrochemical aspects

International Nuclear Information System (INIS)

Volkov, Alexander G.; Volkova-Gugeshashvili, Maya I.; Brown-McGauley, Courtney L.; Osei, Albert J.

2007-01-01

Electrochemical multielectron reactions in photosynthesis and respiration are evaluated by thermodynamic and kinetic analysis. Kharkats and Volkov [Yu.I. Kharkats, A.G. Volkov, Biochim. Biophys. Acta 891 (1987) 56] were the first to present proof that cytochrome c oxidase reduces molecular oxygen by synchronous multielectron mechanism without O 2 - intermediate formation. After this pioneering observation, it became clear that the first step of oxygen reduction is two-electron concerted process. The energy for the H + -pump of cytochrome oxidase is liberated when the third and fourth electrons are added in the last two steps of water formation independent of the reaction pathway. Electrochemical principles govern many biological properties of organisms, such as the generation of electric fields, and the conduction of fast excitation waves. These properties are supported by the function of a variety of natural nanodevices. Ionic channels, as natural nanodevices, control the plasma membrane potential, and the movement of ions across membranes; thereby, regulating various biological functions. Some voltage-gated ion channels work as plasma membrane nanopotentiostats. In plants, excitation waves are possible mechanisms for intercellular and intracellular communication in response to environmental changes. The role of electrified nanointerface of the plasma membrane in signal transduction is discussed as well

Electrochemical maps and movies of the hydrogen evolution reaction on natural crystals of molybdenite (MoS2): basal vs. edge plane activity.

Science.gov (United States)

Bentley, Cameron L; Kang, Minkyung; Maddar, Faduma M; Li, Fengwang; Walker, Marc; Zhang, Jie; Unwin, Patrick R

2017-09-01

Two dimensional (2D) semiconductor materials, such as molybdenum disulfide (MoS 2 ) have attracted considerable interest in a range of chemical and electrochemical applications, for example, as an abundant and low-cost alternative electrocatalyst to platinum for the hydrogen evolution reaction (HER). While it has been proposed that the edge plane of MoS 2 possesses high catalytic activity for the HER relative to the "catalytically inert" basal plane, this conclusion has been drawn mainly from macroscale electrochemical (voltammetric) measurements, which reflect the "average" electrocatalytic behavior of complex electrode ensembles. In this work, we report the first spatially-resolved measurements of HER activity on natural crystals of molybdenite, achieved using voltammetric scanning electrochemical cell microscopy (SECCM), whereby pixel-resolved linear-sweep voltammogram (LSV) measurements have allowed the HER to be visualized at multiple different potentials to construct electrochemical flux movies with nanoscale resolution. Key features of the SECCM technique are that characteristic surface sites can be targeted and analyzed in detail and, further, that the electrocatalyst area is known with good precision (in contrast to many macroscale measurements on supported catalysts). Through correlation of the local voltammetric response with information from scanning electron microscopy (SEM) and atomic force microscopy (AFM) in a multi-microscopy approach , it is demonstrated unequivocally that while the basal plane of bulk MoS 2 (2H crystal phase) possesses significant activity, the HER is greatly facilitated at the edge plane ( e.g. , surface defects such as steps, edges or crevices). Semi-quantitative treatment of the voltammetric data reveals that the HER at the basal plane of MoS 2 has a Tafel slope and exchange current density ( J 0 ) of ∼120 mV per decade and 2.5 × 10 -6 A cm -2 (comparable to polycrystalline Co, Ni, Cu and Au), respectively, while the edge

Hydrogen isotopic substitution experiments in nanostructured porous silicon

International Nuclear Information System (INIS)

Palacios, W.D.; Koropecki, R.R.; Arce, R.D.; Busso, A.

2008-01-01

Nanostructured porous silicon is usually prepared by electrochemical anodization of monocrystalline silicon using a fluorine-rich electrolyte. As a result of this process, the silicon atoms conserve their original crystalline location, and many of the dangling bonds appearing on the surface of the nanostructure are saturated by hydrogen coming from the electrolyte. This work presents an IR study of the effects produced by partial substitution of water in the electrolytic solution by deuterium oxide. The isotopic effects on the IR spectra are analyzed for the as-prepared samples and for the samples subjected to partial thermal effusion of hydrogen and deuterium. We demonstrate that, although deuterium is chemically indistinguishable from hydrogen, it presents a singular behaviour when used in porous silicon preparation. We found that deuterium preferentially bonds forming Si-DH groups. A possible explanation of the phenomenon is presented, based on the different diffusivities of hydrogen and deuterium

Hydrogen isotopic substitution experiments in nanostructured porous silicon

Energy Technology Data Exchange (ETDEWEB)

Palacios, W.D. [Facultad de Ciencias Exactas y Naturales y Agrimensura - (UNNE), Avenida Libertad 5500, 3400 Corrientes (Argentina); Koropecki, R.R. [INTEC (CONICET-UNL), Gueemes 3450, 3000 Santa Fe (Argentina)], E-mail: rkoro@intec.ceride.gov.ar; Arce, R.D. [INTEC (CONICET-UNL), Gueemes 3450, 3000 Santa Fe (Argentina); Busso, A. [Facultad de Ciencias Exactas y Naturales y Agrimensura - (UNNE), Avenida Libertad 5500, 3400 Corrientes (Argentina)

2008-04-30

Nanostructured porous silicon is usually prepared by electrochemical anodization of monocrystalline silicon using a fluorine-rich electrolyte. As a result of this process, the silicon atoms conserve their original crystalline location, and many of the dangling bonds appearing on the surface of the nanostructure are saturated by hydrogen coming from the electrolyte. This work presents an IR study of the effects produced by partial substitution of water in the electrolytic solution by deuterium oxide. The isotopic effects on the IR spectra are analyzed for the as-prepared samples and for the samples subjected to partial thermal effusion of hydrogen and deuterium. We demonstrate that, although deuterium is chemically indistinguishable from hydrogen, it presents a singular behaviour when used in porous silicon preparation. We found that deuterium preferentially bonds forming Si-DH groups. A possible explanation of the phenomenon is presented, based on the different diffusivities of hydrogen and deuterium.

Thermal desorption spectroscopy for investigating hydrogen isotope behavior in materials

International Nuclear Information System (INIS)

Xia Tirui; Yang Hongguang; Zhan Qin; Han Zhibo; He Changshui

2012-01-01

The behavior of hydrogen isotope generated in fusion reactor materials is the key issue for safety and economic operation of fusion reactors and becomes an interesting field. In order to investigate the mechanism of hydrogen isotope such as diffusion, release and retention, a high-sensitivity thermal desorption spectroscopy (TDS) in combination with a quadruple mass spectrometer (QMS) was developed. A major technical breakthrough in ultrahigh vacuum (UHV), low hydrogen background, linear heating and sensitivity calibration of TDS system was made. UHV of l × 10 -7 Pa and low hydrogen background of l × 10 -9 Pa were obtained by combining turbo molecule pump and sputter ion pump. Specimens can be linearly heated up to 1173 K at the rate of 1 to 50 K/min under the MCGS PID software. Sensitivity calibration of the TDS system was accomplished using a special deuterium leak in the detector mode of QMS second electron multiplier. The desorption sensitivity coefficient and the minimum detection limit of deuterium desorption rate are 6.22 × l0 24 s -l · and l.24 × l0 -10 s -1 , respectively. The measurement was also routinely conducted on a specimen of standard, deuterium-containing Zr-4 alloy maintained in the laboratory, so as to validate the TDS method. (authors)

Pumping speed offered by activated carbon at liquid helium temperatures by sorbents adhered to indigenously developed hydroformed cryopanel

International Nuclear Information System (INIS)

Gangradey, Ranjana; Mukherjee, Samiran Shanti; Panchal, Paresh; Nayak, Pratik; Agarwal, Jyoti; Rana, Chirag; Kasthurirengan, S; Mishra, Jyoti Shankar; Patel, Haresh; Bairagi, Pawan; Lambade, Vrushabh; Sayani, Reena

2015-01-01

Towards the aim of developing a pump with large pumping speed of the order of 1 L/(s-cm 2 ) or above for gases like hydrogen and helium through physical adsorption, development of activated carbon based sorbents like granules, spheres, flocked fibres, knitted and non -knitted cloth was carried out. To investigate the pumping speed offered, a test facility SSCF (Small Scale Cryopump Facility) which can take samples of hydroformed cryopanel (a technology developed in India) of size ∼500 mm × 100 mm was set up as per international standards comprising a dome mounted with gauges, calibrated leak valve, gas analyser, sorbent adhered to cryopanel etc. The cryopanel was shielded by chevron baffles. Pumping speed measurements were carried out for gases like hydrogen, helium and argon at a constant panel temperature in the pressure range of 1×10 -7 to 1×10 -4 mbar, and pumping speed was found to be in the range of 2000 L/s for a pressure range 1×10 -6 to 1×10 -4 mbar, and 4000 L/s for pressure range 1×10 -7 mbar and below for a pumping surface area of ∼1000 cm 2 thus giving an average pumping speed of about 2 L/(s-cm 2 ). Using the Monte Carlo codes SSCF was modelled and simulation studies performed. Parameters like sticking coefficient, capture coefficients affecting the pumping speed were studied. This paper describes the experimental setup of SSCF, experimental results and its correlation with Monte-Carlo simulation. (paper)

Direct electron transfer biosensor for hydrogen peroxide carrying nanocomplex composed of horseradish peroxidase and Au-nanoparticle – Characterization and application to bienzyme systems

Directory of Open Access Journals (Sweden)

Yusuke Okawa

2015-09-01

Full Text Available A reagentless electrochemical biosensor for hydrogen peroxide was fabricated. The sensor carries a monolayer of nanocomplex composed of horseradish peroxidase and Au-nanoparticle, and responds to hydrogen peroxide through the highly efficient direct electron transfer at a mild electrode potential without any soluble mediator. Formation of the nanocomplex was studied with visible spectroscopy and size exclusion chromatography. The sensor performance was analyzed based on a hydrodynamic electrochemical technique and enzyme kinetics. The sensor was applied to fabrication of sensors for glucose and uric acid through further modification of the nanocomplex-carrying electrode with the corresponding hydrogen peroxide-generating oxidases, glucose oxidase and urate oxidase, respectively.

Investigations of AB{sub 5}-type negative electrode for nickel-metal hydride cell with regard to electrochemical and microstructural characteristics

Energy Technology Data Exchange (ETDEWEB)

Srivastava, Sumita [Department of Physics, Govt. P.G. College, Uttarkashi, Uttarakhand 249193 (India); Upadhyay, R.K. [Department of Physics, Govt. P.G. College, Rishikesh 249201 (India)

2010-05-01

In the present investigation, AB{sub 5}-type hydrogen storage alloys with compositions Mm{sub 0.8}La{sub 0.2}Ni{sub 3.7}Al{sub 0.38}Co{sub 0.3}Mn{sub 0.5}Mo{sub 0.02} and Mm{sub 0.75}Ti{sub 0.05}La{sub 0.2}Ni{sub 3.7}Al{sub 0.38}Co{sub 0.3}Mn{sub 0.5}Mo{sub 0.02} are synthesized by radio-frequency induction melting. The electrochemical properties are studied through the measurements of discharge capacity, activation process, rate capability, self-discharge rate and cyclic stability of both the electrodes. Pressure-composition isotherms are plotted by converting the electrode potential into the hydrogen pressure following the Nernst equation. The structural and microstructural characterizations are performed by means of X-ray diffraction phase analysis and scanning electron microscopy of as-fabricated and electrochemically tested electrodes. An attempt is made to correlate the observed electrochemical properties with the structural-microstructural characteristics. (author)