Sample records for advanced electrochemical oxidation

  1. Electrochemical Advanced Oxidation Processes (EAOPs) for Environmental Applications

    Microsoft Academic Search

    Mehmet A. Oturan; Enric Brillas

    2007-01-01

    Conventional processes for water treatment are inefficient for the remediation of wastewaters containing toxic and biorecalcitrant organic pollutants. A large number of advanced oxidation processes (AOPs) have been successfully applied to degrade pollutants present in waters. These methods are based on the generation of a very powerful oxidizing agent such as hydroxyl radical ( • OH) in solution, able to

  2. A comparison between Conductive-Diamond Electrochemical Oxidation and other Advanced Oxidation Processes for the treatment of synthetic melanoidins

    Microsoft Academic Search

    P. Cañizares; M. Hernández-Ortega; M. A. Rodrigo; C. E. Barrera-Díaz; G. Roa-Morales; C. Sáez

    2009-01-01

    In this study, three technologies classified as Advanced Oxidation Processes (Conductive-Diamond Electrochemical Oxidation (CDEO), ozonation and Fenton oxidation) have been compared to treat wastes produced in fermentation processes, and characterized by a significant color and a high organic load. Results of CDEO seem to strongly depend on the addition of an electrolyte salt, not only to decrease the energy cost

  3. Electrochemically Deposited Ceria Structures for Advanced Solid Oxide Fuel Cells

    NASA Astrophysics Data System (ADS)

    Brown, Evan C.

    As the pursuit towards emissions reduction intensifies with growing interest and nascent technologies, solid oxide fuel cells (SOFCs) remain an illustrious candidate for achieving our goals. Despite myriad advantages, SOFCs are still too costly for widespread deployment, even as unprecedented materials developments have recently emerged. This suggests that, in addition to informed materials selection, the necessary power output--and, thereby, cost-savings--gains must come from the fuel cell architecture. The work presented in this manuscript primarily investigates cathodic electrochemical deposition (CELD) as a scalable micro-/nanoscale fabrication tool for engineering ceria-based components in a SOFC assembly. Also, polymer sphere lithography was utilized to deposit fully connected, yet fully porous anti-dot metal films on yttira-stabilized zirconia (YSZ) with specific and knowable geometries, useful for mechanistic studies. Particular attention was given to anode structures, for which anti-dot metal films on YSZ served as composite substrates for subsequent CELD of doped ceria. By tuning the applied potential, a wide range of microstructures from high surface area coatings to planar, thin films was possible. In addition, definitive deposition was shown to occur on the electronically insulating YSZ surfaces, producing quality YSZ|ceria interfaces. These CELD ceria deposits exhibited promising electrochemical activity, as probed by A.C. Impedance Spectroscopy. In an effort to extend its usefulness as a SOFC fabrication tool, the CELD of ceria directly onto common SOFC cathode materials without a metallic phase was developed, as well as templated deposition schemes producing ceria nanowires and inverse opals.

  4. Post-treatment of reclaimed waste water based on an electrochemical advanced oxidation process

    NASA Technical Reports Server (NTRS)

    Verostko, Charles E.; Murphy, Oliver J.; Hitchens, G. D.; Salinas, Carlos E.; Rogers, Tom D.

    1992-01-01

    The purification of reclaimed water is essential to water reclamation technology life-support systems in lunar/Mars habitats. An electrochemical UV reactor is being developed which generates oxidants, operates at low temperatures, and requires no chemical expendables. The reactor is the basis for an advanced oxidation process in which electrochemically generated ozone and hydrogen peroxide are used in combination with ultraviolet light irradiation to produce hydroxyl radicals. Results from this process are presented which demonstrate concept feasibility for removal of organic impurities and disinfection of water for potable and hygiene reuse. Power, size requirements, Faradaic efficiency, and process reaction kinetics are discussed. At the completion of this development effort the reactor system will be installed in JSC's regenerative water recovery test facility for evaluation to compare this technique with other candidate processes.

  5. Advanced treatment of biologically pretreated coking wastewater by electrochemical oxidation using boron-doped diamond electrodes.

    PubMed

    Zhu, Xiuping; Ni, Jinren; Lai, Peng

    2009-09-01

    Electrochemical oxidation is a promising technology to treatment of bio-refractory wastewater. Coking wastewater contains high concentration of refractory and toxic compounds and the water quality usually cannot meet the discharge standards after conventional biological treatment processes. This paper initially investigated the electrochemical oxidation using boron-doped diamond (BDD) anode for advanced treatment of coking wastewater. Under the experimental conditions (current density 20-60mAcm(-2), pH 3-11, and temperature 20-60 degrees C) using BDD anode, complete mineralization of organic pollutants was almost achieved, and surplus ammonia-nitrogen (NH(3)-N) was further removed thoroughly when pH was not adjusted or at alkaline value. Moreover, the TOC and NH(3)-N removal rates in BDD anode cell were much greater than those in other common anode systems such as SnO(2) and PbO(2) anodes cells. Given the same target to meet the National Discharge Standard of China, the energy consumption of 64kWhkgCOD(-1) observed in BDD anode system was only about 60% as much as those observed in SnO(2) and PbO(2) anode systems. Further investigation revealed that, in BDD anode cell, organic pollutants were mainly degraded by reaction with free hydroxyl radicals and electrogenerated oxidants (S(2)O(8)(2-), H(2)O(2), and other oxidants) played a less important role, while direct electrochemical oxidation and indirect electrochemical oxidation mediated by active chlorine can be negligible. These results showed great potential of BDD anode system in engineering application as a final treatment of coking wastewater. PMID:19595422

  6. Solid oxide electrochemical reactor science

    Microsoft Academic Search

    Neal P. Sullivan; Ellen Beth Stechel; Connor J. Moyer; Andrea Ambrosini; Robert J. Key

    2010-01-01

    Solid-oxide electrochemical cells are an exciting new technology. Development of solid-oxide cells (SOCs) has advanced considerable in recent years and continues to progress rapidly. This thesis studies several aspects of SOCs and contributes useful information to their continued development. This LDRD involved a collaboration between Sandia and the Colorado School of Mines (CSM) ins solid-oxide electrochemical reactors targeted at solid

  7. Electrochemical advanced oxidation for cold incineration of the pharmaceutical ranitidine: mineralization pathway and toxicity evolution.

    PubMed

    Olvera-Vargas, Hugo; Oturan, Nihal; Brillas, Enric; Buisson, Didier; Esposito, Giovanni; Oturan, Mehmet A

    2014-12-01

    Ranitidine (RNTD) is a widely prescribed histamine H2-receptor antagonist whose unambiguous presence in water sources appointed it as an emerging pollutant. Here, the degradation of 0.1 mM of this drug in aqueous medium was studied by electrochemical advanced oxidation processes (EAOPs) like anodic oxidation with electrogenerated H2O2 and electro-Fenton using Pt/carbon-felt, BDD/carbon-felt and DSA-Ti/RuO2–IrO2/carbon-felt cells. The higher oxidation power of the electro-Fenton process using a BDD anode was demonstrated. The oxidative degradation of RNTD by the electrochemically generated OH radicals obeyed a pseudo-first order kinetics. The absolute rate constant for its hydroxylation reaction was 3.39 × 109 M?1 s?1 as determined by the competition kinetics method. Almost complete mineralization of the RNTN solution was reached by using a BDD anode in both anodic oxidation with electrogenerated H2O2 and electro-Fenton processes. Up to 11 cyclic intermediates with furan moiety were detected from the degradation of RNTD, which were afterwards oxidized to short-chain carboxylic acids before their mineralization to CO2 and inorganic ions such as NH4+, NO3? and SO42?. Based on identified products, a plausible reaction pathway was proposed for RNTD mineralization. Toxicity assessment by the Microtox® method revealed that some cyclic intermediates are more toxic than the parent molecule. Toxicity was quickly removed following the almost total mineralization of the treated solution. Overall results confirm the effectiveness of EAOPs for the efficient removal of RNTD and its oxidation by-products from water. PMID:25461930

  8. Application of electrochemical advanced oxidation processes to the mineralization of the herbicide diuron.

    PubMed

    Pipi, Angelo R F; Sirés, Ignasi; De Andrade, Adalgisa R; Brillas, Enric

    2014-08-01

    Here, solutions with 0.185mM of the herbicide diuron of pH 3.0 have been treated by electrochemical advanced oxidation processes (EAOPs) like electrochemical oxidation with electrogenerated H2O2 (EO-H2O2), electro-Fenton (EF) and UVA photoelectro-Fenton (PEF) or solar PEF (SPEF). Trials were performed in stirred tank reactors of 100mL and in a recirculation flow plant of 2.5L using a filter-press reactor with a Pt or boron-doped diamond (BDD) anode and an air-diffusion cathode for H2O2 electrogeneration. Oxidant hydroxyl radicals were formed from water oxidation at the anode and/or in the bulk from Fenton's reaction between added Fe(2+) and generated H2O2. In both systems, the relative oxidation ability of the EAOPs increased in the sequence EO-H2O2

  9. Incorporation of electrochemical advanced oxidation processes in a multistage treatment system for sanitary landfill leachate.

    PubMed

    Moreira, Francisca C; Soler, J; Fonseca, Amélia; Saraiva, Isabel; Boaventura, Rui A R; Brillas, Enric; Vilar, Vítor J P

    2015-09-15

    The current study has proved the technical feasibility of including electrochemical advanced oxidation processes (EAOPs) in a multistage strategy for the remediation of a sanitary landfill leachate that embraced: (i) first biological treatment to remove the biodegradable organic fraction, oxidize ammonium and reduce alkalinity, (ii) coagulation of the bio-treated leachate to precipitate humic acids and particles, followed by separation of the clarified effluent, and (iii) oxidation of the resulting effluent by an EAOP to degrade the recalcitrant organic matter and increase its biodegradability so that a second biological process for removal of biodegradable organics and nitrogen content could be applied. The influence of current density on an UVA photoelectro-Fenton (PEF) process was firstly assessed. The oxidation ability of various EAOPs such as electro-Fenton (EF) with two distinct initial total dissolved iron concentrations ([TDI]0), PEF and solar PEF (SPEF) was further evaluated and these processes were compared with their analogous chemical ones. A detailed assessment of the two first treatment stages was made and the biodegradability enhancement during the SPEF process was determined by a Zahn-Wellens test to define the ideal organics oxidation state to stop the EAOP and apply the second biological treatment. The best current density was 200 mA cm(-2) for a PEF process using a BDD anode, [TDI]0 of 60 mg L(-1), pH 2.8 and 20 °C. The relative oxidation ability of EAOPs increased in the order EF with 12 mg [TDI]0 L(-1) < EF with 60 mg [TDI]0 L(-1) < PEF with 60 mg [TDI]0 L(-1) ? SPEF with 60 mg [TDI]0 L(-1), using the abovementioned conditions. While EF process was much superior to the Fenton one, the superiority of PEF over photo-Fenton was less evident and SPEF attained similar degradation to solar photo-Fenton. To provide a final dissolved organic carbon (DOC) of 163 mg L(-1) to fulfill the discharge limits into the environment after a second biological process, 6.2 kJ L(-1) UV energy and 36 kWh m(-3) electrical energy were consumed using SPEF with a BDD anode at 200 mA cm(-2), 60 mg [TDI]0 L(-1), pH 2.8 and 20 °C. PMID:26140989

  10. ELECTROCHEMICAL ADVANCED OXIDATION TREATMENTS OF ACIDIC AQUEOUS SOLUTIONS CONTAINING THE AMINOACID ?-METHYLPHENYLGLYCINE USING A BORON-DOPED DIAMOND ANODE

    Microsoft Academic Search

    Anna Serra; Xavier Domènech; José Peral; Conchita Arias; Enric Brillas

    The degradation of a solution containing 500 mg L-1 of the aminoacid ?-methylphenylglycine, 10 mg L-1 Fe2+ and 0.05 M Na2O4 at pH 3.0 has been studied by means of electrochemical advanced oxidation processes like electro-Fenton (EF) and solar photoelectro-Fenton (SPEF) using an undivided electrolytic cell with a boron-doped diamond (BDD) anode and an O2-diffusion cathode. Under these conditions, very

  11. Electrochemical oxidation of chemical weapons

    SciTech Connect

    Surma, J.E.

    1994-05-01

    Catalyzed electrochemical oxidation (CEO), a low-temperature electrochemical oxidation technique, is being examined for its potential use in destroying chemical warfare agents. The CEO process oxidizes organic compounds to form carbon dioxide and water. A bench-scale CEO system was used in three separate tests sponsored by the US Department of Energy`s (DOE) Office of Intelligence and National Security through the Advanced Concepts Program. The tests examined the effectiveness of CEO in destroying sarin (GB), a chemical nerve agent. The tests used 0.5 mL, 0.95 mL, and 1.0 mL of GB, corresponding to 544 mg, 816 mg, and 1,090 mg, respectively, of GB. Analysis of the off gas showed that, under continuous processing of the GB agent, destruction efficiencies of better than six 9s (99.9999% destroyed) could be achieved.

  12. Electrochemical advanced oxidation process for water treatment using DiaChem ® electrodes

    Microsoft Academic Search

    I. Tröster; M. Fryda; D. Herrmann; L. Schäfer; W. Hänni; A. Perret; M. Blaschke; A. Kraft; M. Stadelmann

    2002-01-01

    Currently applied water treatment techniques consist of a combination of different methods to achieve the elimination of harmful pollutants. Within this field, the capability of electrochemical water treatment is still not exhaustively exploited due to the lack of for instance appropriate electrode materials. The chemical inertness and unique electrochemical properties of boron-doped diamond electrodes present great potential for electrochemical water

  13. Solid oxide electrochemical reactor science.

    SciTech Connect

    Sullivan, Neal P. (Colorado School of Mines, Golden, CO); Stechel, Ellen Beth; Moyer, Connor J. (Colorado School of Mines, Golden, CO); Ambrosini, Andrea; Key, Robert J. (Colorado School of Mines, Golden, CO)

    2010-09-01

    Solid-oxide electrochemical cells are an exciting new technology. Development of solid-oxide cells (SOCs) has advanced considerable in recent years and continues to progress rapidly. This thesis studies several aspects of SOCs and contributes useful information to their continued development. This LDRD involved a collaboration between Sandia and the Colorado School of Mines (CSM) ins solid-oxide electrochemical reactors targeted at solid oxide electrolyzer cells (SOEC), which are the reverse of solid-oxide fuel cells (SOFC). SOECs complement Sandia's efforts in thermochemical production of alternative fuels. An SOEC technology would co-electrolyze carbon dioxide (CO{sub 2}) with steam at temperatures around 800 C to form synthesis gas (H{sub 2} and CO), which forms the building blocks for a petrochemical substitutes that can be used to power vehicles or in distributed energy platforms. The effort described here concentrates on research concerning catalytic chemistry, charge-transfer chemistry, and optimal cell-architecture. technical scope included computational modeling, materials development, and experimental evaluation. The project engaged the Colorado Fuel Cell Center at CSM through the support of a graduate student (Connor Moyer) at CSM and his advisors (Profs. Robert Kee and Neal Sullivan) in collaboration with Sandia.

  14. Phenol degradation by advanced electrochemical oxidation process electro-Fenton using a carbon felt cathode

    Microsoft Academic Search

    Marcio Pimentel; Nihal Oturan; Marcia Dezotti; Mehmet A. Oturan

    2008-01-01

    Oxidation of phenol in aqueous media by electro-Fenton process using carbon felt cathode has been studied. The salts of iron, cobalt, manganese, and copper were used to provide the metal cations as catalyst of Fenton reaction to produce hydroxyl radicals. 10?4M of soluble iron(II) sulfate salt supplied the optimum catalytic condition, allowing to remove 100% of total organic carbon (TOC)

  15. Dechlorination by combined electrochemical reduction and oxidation

    Microsoft Academic Search

    CONG Yan-qing; WU Zu-cheng; TAN Tian-en

    Chlorophenols are typical priority pollutants listed by USEPA (U.S. Environmental Protection Agency). The removal of chlorophenol could be carried out by a combination of electrochemical reduction and oxidation method. Results showed that it was feasible to degrade contaminants containing chlorine atoms by electrochemical reduction to form phenol, which was further degraded on the anode by electrochemical oxidation. Chlorophenol removal rate

  16. Electrochemical oxidation for landfill leachate treatment

    SciTech Connect

    Deng, Yang [Department of Civil, Architectural and Environmental Engineering, McArthur Building, Room 325, 1251 Memorial Dr., University of Miami, Coral Gables, FL 33146 (United States)], E-mail: dengyang7@yahoo.com; Englehardt, James D. [Department of Civil, Architectural and Environmental Engineering, McArthur Building, Room 325, 1251 Memorial Dr., University of Miami, Coral Gables, FL 33146 (United States)

    2007-07-01

    This paper aims at providing an overview of electrochemical oxidation processes used for treatment of landfill leachate. The typical characteristics of landfill leachate are briefly reviewed, and the reactor designs used for electro-oxidation of leachate are summarized. Electrochemical oxidation can significantly reduce concentrations of organic contaminants, ammonia, and color in leachate. Pretreatment methods, anode materials, pH, current density, chloride concentration, and other additional electrolytes can considerably influence performance. Although high energy consumption and potential chlorinated organics formation may limit its application, electrochemical oxidation is a promising and powerful technology for treatment of landfill leachate.

  17. Electrochemical oxidation of WC in acidic sulphate solution

    Microsoft Academic Search

    Benedetto Bozzini; Gian Pietro De Gaudenzi; Ameriga Fanigliulo; Claudio Mele

    2004-01-01

    The electrochemical oxidation of WC in aqueous solutions is critical for the functional stability of hardmetals in aggressive environments. The oxidation of WC and the nature of the oxides formed in 0.1 M sulphuric acid under electrochemical polarisation have been studied by electrochemical methods (cyclic voltammetry, chronoamperometry). The structure and composition of the electrochemically treated surfaces has been analysed by

  18. Electrochemical Sensing of Nitric Oxide with Functionalized Graphene Electrodes

    E-print Network

    Aksay, Ilhan A.

    Electrochemical Sensing of Nitric Oxide with Functionalized Graphene Electrodes Yifei M. Liu: The intrinsic electrocatalytic properties of functionalized graphene sheets (FGSs) in nitric oxide (NO) sensing and lower detection limits should be feasible with FGSs. KEYWORDS: nitric oxide, electrochemical sensing

  19. Feasibility of an electrochemically assisted Fenton method using Fe(2 +)/HOCl system as an advanced oxidation process.

    PubMed

    Kishimoto, N; Sugimura, E

    2010-01-01

    The feasibility of an electrochemically assisted Fenton treatment using a Fenton-type reaction of ferrous iron (Fe(2 + )) and hypochlorous acid (HOCl) is discussed in this research. The reactor used was composed of an undivided single cell with a ruthenium dioxide-coated titanium anode and a stainless steel cathode, in which Fe(2 + ) and HOCl were catalytically regenerated from ferric iron at the cathode and chloride ion at the anode, respectively. Although the reactor functioned well, the degradation rate of 1,4-dioxane as a hydroxyl radical probe decreased at the current density more than 6.92 mA cm(-2). The decrease in degradation rate was inferred to be caused by the vain consumption of hydroxyl radicals by excess HOCl and the deposition of ferric hydroxide on the cathode at relatively high current density. The current efficiency of 1,4-dioxane removal remained more than 90% at the current density less than 6.92 mA cm(-2) and the iron concentration not less than 1.0 mmol L(-1). Consequently, this technique is thought to be applicable to the treatment of wastewater containing high concentration of chloride ion such as landfill leachate, scrubber wastewater from incineration plants, etc. PMID:21076218

  20. Toxicity assessment of the water used for human consumption from the Cameron/Tuba City abandoned uranium mining area prior/after the combined electrochemical treatment/advanced oxidation.

    PubMed

    Gajski, Goran; Oreš?anin, Višnja; Geri?, Marko; Kollar, Robert; Lovren?i? Mikeli?, Ivanka; Garaj-Vrhovac, Vera

    2015-01-01

    The purpose of this work was detailed physicochemical, radiological, and toxicological characterization of the composite sample of water intended for human consumption in the Cameron/Tuba City abandoned uranium mining area before and after a combined electrochemical/advanced oxidation treatment. Toxicological characterization was conducted on human lymphocytes using a battery of bioassays. On the bases of the tested parameters, it could be concluded that water used for drinking from the tested water sources must be strictly forbidden for human and/or animal consumption since it is extremely cytogenotoxic, with high oxidative stress potential. A combined electrochemical treatment and posttreatment with ozone and UV light decreased the level of all physicochemical and radiological parameters below the regulated values. Consequently, the purified sample was neither cytotoxic nor genotoxic, indicating that the presented method could be used for the improvement of water quality from the sites highly contaminated with the mixture of heavy metals and radionuclides. PMID:25087498

  1. Cadmium oxide as electrochemical probe for nitrophenols

    Microsoft Academic Search

    K. Giribabu; R. Suresh; V. Narayanan; L. Vijayalakshmi; A. Stephen

    2011-01-01

    Cadmium oxide was synthesized using cadmium acetate and oleic acid as the precursors. The formed cadmium oxide nanoparticles were characterized by using XRD and cyclic voltammetry. The electrochemical detection of pollutants [4-Nitrophenol(4-NP) and 2-Nitrophenol(2-NP)] was carried out by coating the cadmium oxide onto the glassy carbon electrode (GCE) by drop coating method. The electrocatalytic performance of the modified GCE electrode

  2. A high-performance flexible fibre-shaped electrochemical capacitor based on electrochemically reduced graphene oxide.

    PubMed

    Li, Yingru; Sheng, Kaixuan; Yuan, Wenjing; Shi, Gaoquan

    2013-01-11

    A fibre-shaped solid electrochemical capacitor based on electrochemically reduced graphene oxide has been fabricated, exhibiting high specific capacitance and rate capability, long cycling life and attractive flexibility. PMID:23183591

  3. Indirect oxidation effect in electrochemical oxidation treatment of landfill leachate

    Microsoft Academic Search

    Li-Choung Chiang; Juu-En Chang; Ten-Chin Wen

    1995-01-01

    Treatment of a low BODCOD ratio landfill leachate was conducted by means of electrochemical oxidation process in this investigation. Under the operating conditions of 15 A\\/dm2 current density and 7500 mg\\/l additional chloride concentration, 92% of the COD in the landfall leachate was removed after electrolysis for 240 min with a ternary Sn?Pd?Ru oxide-coated titanium (SPR) anode. At the same

  4. Fabrication of advanced electrochemical energy materials using sol-gel processing techniques

    NASA Technical Reports Server (NTRS)

    Chu, C. T.; Chu, Jay; Zheng, Haixing

    1995-01-01

    Advanced materials play an important role in electrochemical energy devices such as batteries, fuel cells, and electrochemical capacitors. They are being used as both electrodes and electrolytes. Sol-gel processing is a versatile solution technique used in fabrication of ceramic materials with tailored stoichiometry, microstructure, and properties. The application of sol-gel processing in the fabrication of advanced electrochemical energy materials will be presented. The potentials of sol-gel derived materials for electrochemical energy applications will be discussed along with some examples of successful applications. Sol-gel derived metal oxide electrode materials such as V2O5 cathodes have been demonstrated in solid-slate thin film batteries; solid electrolytes materials such as beta-alumina for advanced secondary batteries had been prepared by the sol-gel technique long time ago; and high surface area transition metal compounds for capacitive energy storage applications can also be synthesized with this method.

  5. Solid oxide electrochemical cell fabrication process

    DOEpatents

    Dollard, Walter J. (Churchill Borough, PA); Folser, George R. (Lower Burrell, PA); Pal, Uday B. (Cambridge, MA); Singhal, Subhash C. (Murrysville, PA)

    1992-01-01

    A method to form an electrochemical cell (12) is characterized by the steps of thermal spraying stabilized zirconia over a doped lanthanum manganite air electrode tube (14) to provide an electrolyte layer (15), coating conductive particles over the electrolyte, pressurizing the outside of the electrolyte layer, feeding halide vapors of yttrium and zirconium to the outside of the electrolyte layer and feeding a source of oxygen to the inside of the electrolyte layer, heating to cause oxygen reaction with the halide vapors to close electrolyte pores if there are any and to form a metal oxide coating on and between the particles and provide a fuel electrode (16).

  6. Mineralization of Drugs in Aqueous Medium by Advanced Oxidation Processes

    Microsoft Academic Search

    José Antonio Garrido; Enric Brillas; Pere Lluís Cabot; Francesc Centellas; Conchita Arias; Rosa María Rodríguez

    2007-01-01

    At present chemical (AOPs) and electrochemical (EAOPs) advanced oxidation processes with ability to destroy organic pollutants in waters are being developed. These methods are based on the production of hydroxyl radical ( •OH) as oxidant. In AOPsOH radical can be obtained from Fenton's reaction between Fe 2+ and H 2O2 added to the medium, photoreduction of Fe 3+ species or

  7. Electrochemical and microstructural study of oxide films formed electrochemically at microcrystalline Al-Fe-V-Si alloys.

    PubMed

    Thomas, S C; Birss, V I; Steele, D; Tessier, D

    1995-07-01

    A recent advance in metallurgical technology has been the application of rapid solidification techniques to Al alloy production. FVS0812 is the designation given to a microcrystalline Al-based alloy consisting of 8 wt% Fe, 1 wt% V and 2 wt% Si. It is a two-phase alloy, consisting of ca. 27 vol percent of approximately spherical Fe-V-Si-rich dispersoids in an essentially pure Al matrix. The high strength, low density properties of this advanced material, and other related alloys, have not yet been realized, however, due, in part, to the inability of the alloy to form a thick, adherent, abrasion-resistant outer surface oxide film, a feature readily achieved at conventional Al alloys by normal anodizing methods. The present research has involved an electro-chemical study of oxide film growth at the 812 alloy, with the specific goals being to seek an understanding of the origin of the oxide film growth problem and ultimately to propose alternative approaches to the formation of a thick, stable oxide film at this material. The techniques used in this research have included electrochemical methodologies such as cyclic voltammetry and electrochemical impedance spectroscopy. Crucial information has been obtained through transmission electron microscopy (TEM) of ultramicrotomed specimens. Experiments were carried out initially in neutral borate solutions to characterize the compact barrier oxide film formed in this environment and expected to be present beneath the porous oxide film formed in the normal sulfuric acid anodizing medium.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7549001

  8. Electrochemical reduction and oxidation of molybdenum oxides in propylene carbonate

    SciTech Connect

    Vereshchagina, I.S.; Tikhanov, K.I.; Makhalov, N.A.

    1982-02-10

    In the search for cathodes that can be used in reversibly functioning power sources with aprotic electrolytes, the molybdenum oxide electrode was revealed as promising. The high specific energy of power sources based on the Li-MoO/sub 3/ system and the cycling performance of the MoO/sub 3/ electrode have been pointed out. However, little is known concerning the processes taking place at the electrode and concerning the factors influencing reversibility of the electrodes. It was the aim of the present work to examine the electrochemical behavior of the molybdenum oxide electrode in 1 M LiClO/sub 4/ solution in propylene carbonate (PC) during cycling.

  9. Tutorial Review: Electrochemical Nitric Oxide Sensors for Physiological Measurements

    PubMed Central

    Privett, Benjamin J.; Shin, Jae Ho; Schoenfisch, Mark H.

    2013-01-01

    Summary The important biological roles of nitric oxide (NO) have prompted the development of analytical techniques capable of sensitive and selective detection of NO. Electrochemical sensing, more than any other NO-detection method, embodies the parameters necessary for quantifying NO in challenging physiological environments such as blood and the brain. Herein, we provide a broad overview of the field of electrochemical NO sensors, including design, fabrication, and analytical performance characteristics. Both electrochemical sensors and biological applications are detailed. PMID:20502795

  10. Electrode electrolyte interlayers containing cerium oxide for electrochemical fuel cells

    DOEpatents

    Borglum, Brian P. (Edgewood, PA); Bessette, Norman F. (N. Huntingdon, PA)

    2000-01-01

    An electrochemical cell is made having a porous fuel electrode (16) and a porous air electrode (13), with solid oxide electrolyte (15) therebetween, where the air electrode surface opposing the electrolyte has a separate, attached, dense, continuous layer (14) of a material containing cerium oxide, and where electrolyte (16) contacts the continuous oxide layer (14), without contacting the air electrode (13).

  11. Oxide modified air electrode surface for high temperature electrochemical cells

    DOEpatents

    Singh, Prabhakar (Export, PA); Ruka, Roswell J. (Churchill Boro, Allegheny County, PA)

    1992-01-01

    An electrochemical cell is made having a porous cermet electrode (16) and a porous lanthanum manganite electrode (14), with solid oxide electrolyte (15) between them, where the lanthanum manganite surface next to the electrolyte contains a thin discontinuous layer of high surface area cerium oxide and/or praseodymium oxide, preferably as discrete particles (30) in contact with the air electrode and electrolyte.

  12. pH sensor properties of electrochemically grown iridium oxide

    Microsoft Academic Search

    W. Olthuis; M. A. M. Robben; P. Bergveld; M. Bos; Linden van der W. E

    1990-01-01

    The open-circuit potential of an electrochemically grown iridium oxide film is measured and shows a pH sensitivity between ?60 and ?80 mV\\/pH. This sensitivity is found to depend on the state of oxidation of the iridium oxide film; for a higher state of oxidation (or more of the oxide in the high valence state), the sensitivity is also higher. This

  13. Technology advancement of the electrochemical CO2 concentrating process

    NASA Technical Reports Server (NTRS)

    Schubert, F. H.; Heppner, D. B.; Hallick, T. M.; Woods, R. R.

    1979-01-01

    Two multicell, liquid-cooled, advanced electrochemical depolarized carbon dioxide concentrator modules were fabricated. The cells utilized advanced, lightweight, plated anode current collectors, internal liquid cooling and lightweight cell frames. Both were designed to meet the carbon dioxide removal requirements of one-person, i.e., 1.0 kg/d (2.2 lb/d).

  14. Innovative oxide materials for electrochemical energy conversion

    NASA Astrophysics Data System (ADS)

    Wachsman, Eric D.

    2012-02-01

    Research in functional materials has progressed from those materials exhibiting structural to electronic functionality. The study of ion conducting ceramics ushers in a new era of ``chemically functional materials.'' This chemical functionality arises out of the defect equilibria of these materials, and results in the ability to transport chemical species and actively participate in chemical reactions at their surface. Moreover, this chemical functionality provides a promise for the future whereby the harnessing of our natural hydrocarbon energy resources can shift from inefficient and polluting combustion - mechanical methods to direct electrochemical conversion. The unique properties of these materials and their applications will be described. The focus will be on the application of ion conducting ceramics to energy conversion and storage, chemical sensors, chemical separation and conversion, and life support systems. Results presented will include development of record high power density (3 kW/kg) solid oxide fuel cells, NOx/CO species selective solid-state sensors, high yield membrane reactors, and regenerative life support systems that reduce CO2 to O2 and solid C.

  15. Advanced oxidation processes for the treatment of wastes polluted with azoic dyes

    Microsoft Academic Search

    M. Faouzi; P. Cañizares; A. Gadri; J. Lobato; B. Nasr; R. Paz; M. A. Rodrigo; C. Saez

    2006-01-01

    In this work, synthetic wastes polluted with azoic dyes have been treated with conductive-diamond electrochemical oxidation, Fenton oxidation and ozonation. Eriochrome black T (EBT), methyl orange (MO) and congo red (CR) were selected as model pollutants. Although the three technologies are classified as advanced oxidation processes and, consequently hydroxyl radicals are assumed to be involved in their oxidation mechanism, the

  16. Nanostructured transition metal oxides for aqueous hybrid electrochemical supercapacitors

    Microsoft Academic Search

    T. Cottineau; M. Toupin; T. Delahaye; T. Brousse; D. Bélanger

    2006-01-01

    In this paper, we wish to present an overview of the research carried out in our laboratories with low-cost transition metal\\u000a oxides (manganese dioxide, iron oxide and vanadium oxide) as active electrode materials for aqueous electrochemical supercapacitors.\\u000a More specifically, the paper focuses on the approaches that have been used to increase the capacitance of the metal oxides\\u000a and the cell

  17. Electrochemical and partial oxidation of methane

    NASA Astrophysics Data System (ADS)

    Singh, Rahul

    2008-10-01

    Hydrogen has been the most common fuel used for the fuel cell research but there remains challenging technological hurdles and storage issues with hydrogen fuel. The direct electrochemical oxidation of CH4 (a major component of natural gas) in a solid oxide fuel cell (SOFC) to generate electricity has a potential of commercialization in the area of auxiliary and portable power units and battery chargers. They offer significant advantages over an external reformer based SOFC, namely, (i) simplicity in the overall system architecture and balance of plant, (ii) more efficient and (iii) availability of constant concentration of fuel in the anode compartment of SOFC providing stability factor. The extreme operational temperature of a SOFC at 700-1000°C provides a thermodynamically favorable pathway to deposit carbon on the most commonly used Ni anode from CH4 according to the following reaction (CH4 = C + 2H2), thus deteriorating the cell performance, stability and durability. The coking problem on the anode has been a serious and challenging issue faced by the catalyst research community worldwide. This dissertation presents (i) a novel fabricated bi-metallic Cu-Ni anode by electroless plating of Cu on Ni anode demonstrating significantly reduced or negligible coke deposition on the anode for CH4 and natural gas fuel after long term exposure, (ii) a thorough microstructural examination of Ni and Cu-Ni anode exposed to H2, CH4 and natural gas after long term exposure at 750°C by scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction and (iii) in situ electrochemical analysis of Ni and Cu-Ni for H2, CH4 and natural gas during long term exposure at 750°C by impedance spectroscopy. A careful investigation of variation in the microstructure and performance characteristics (voltage-current curve and impedance) of Ni and Cu-Ni anode before and after a long term exposure of CH4 and natural gas would allow us to test the validation of a negligible coke formation on the novel fabricated anode by electroless plating process. Hydrogen is an environmentally cleaner source of energy. The recent increase in the demand of hydrogen as fuel for all types of fuel cells and petroleum refining process has boosted the need of production of hydrogen. Methane, a major component of natural gas is the major feedstock for production of hydrogen. The route of partial oxidation of methane to produce syngas (CO + H2) offers significant advantages over commercialized steam reforming process for higher efficiency and lower energy requirements. Partial oxidation of methane was studied by pulsing O2 into a CH4 flow over Rh/Al2O3 in a sequence of in situ infrared (IR) cell and fixed bed reactor at 773 K. The results obtained from the sequence of an IR cell followed by a fixed bed reactor show that (i) adsorbed CO produced possesses a long residence time, indicating that adsorbed oxygen leading to the formation of CO is significantly different from those leading to CO2 and (ii) CO2 is not an intermediate species for the formation of CO. In situ IR of pulse reaction coupled with alternating reactor sequence is an effective approach to study the primary and secondary reactions as well as the nature of their adsorbed species. As reported earlier, hydrogen remains to be the most effective fuel for fuel cells, the production of high purity hydrogen from naturally available resources such as coal, petroleum, and natural gas requires a number of energy-intensive steps, making fuel cell processes for stationary electric power generation prohibitively uneconomic. Direct use of coal or coal gas as the feed is a promising approach for low cost electricity generation. Coal gas solid oxide fuel cell was studied by pyrolyzing Ohio #5 coal to coal gas and transporting to a Cu anode solid oxide fuel cell to generate power. The study of coal-gas solid oxide fuel cell is divided into two sections, i.e., (i) understanding the composition of coal gas by in situ infrared spectroscopy combined with mass spectrometry and (ii) evaluating the perfo

  18. Electrochemical cell current requirements for toxic organic waste destruction in Ce(IV)-mediated electrochemical oxidation process

    Microsoft Academic Search

    Vasily V. Kokovkin; Sang Joon Chung; Subramanian Balaji; Manickam Matheswaran; Il-Shik Moon

    2007-01-01

    The electrochemical cell for cerium oxidation and reactor for organic destruction are the most important operation units for\\u000a the successful working mediated electrochemical oxidation (MEO) process. In this study, electrochemical cells with DSA electrodes\\u000a of two types, single stack and double stack connected in series, were used. The performances towards the electrochemical generation\\u000a of Ce(IV) in nitric acid media at

  19. Size dependent electrochemical properties of reduced graphite oxide

    NASA Astrophysics Data System (ADS)

    Tran, Minh-Hai; Yang, Cheol-Soo; Yang, Sunhye; Kim, Ick-Jun; Jeong, Hae Kyung

    2014-07-01

    Size dependent electrochemical properties of reduced graphite oxide are investigated. Two kinds, 5 and 149 ?m, of natural graphite as a precursor are used to synthesize graphite oxide and to reduce it by hydrazine. The precursor of smaller grain size provides efficient oxidation and reduction, resulting in improved electrochemical properties compared to the precursor of larger grain size for energy storage applications. Furthermore, the influence of hydrazine concentration on the reduction is investigated, finding that too much hydrazine causes side effects on the reduction.

  20. Electrochemical Oxidation of Ammonia on Ir Anode in Potential Fixed Electrochemical Sensor

    Microsoft Academic Search

    Yi-ping HAN; Peng LUO; Chen-xin CAI; Lei XIE; Tian-hong LU

    2008-01-01

    Ir catalyst possesses a good electrocatalytic activity and selectivity for the oxidation of NH3 and\\/or NH4OH at Ir anode in the potential fixed electrochemical sensor with the neutral solution. Owing to the same electrochemical behavior of NH3 and NH4OH in a NaClO4 solution, NH4OH can be used instead of NH3 for the experimental convenience. It was found that the potential

  1. Electrochemical supercapacitor material based on manganese oxide: preparation and characterization

    Microsoft Academic Search

    Junhua Jiang; Anthony Kucernak

    2002-01-01

    A novel class of electrochemical supercapacitor electrode material has been electrochemically synthesized from a manganese halide complex in water-containing acetonitrile electrolyte at room temperature. This material has been physically and chemically characterized by scanning electron microscopy, X-ray photoelectron microscopy (XPS), FT-Raman microscopy and cyclic voltammetry. XPS and FT-Raman characterization suggest that this material is composed of manganese oxide with a

  2. Electrochemical oxidation of quercetin in the presence of benzenesulfinic acids

    Microsoft Academic Search

    D Nematollahi; M Malakzadeh

    2003-01-01

    Electrochemical oxidation of quercetin has been studied in the absence and presence of benzenesulfinic acids as nucleophiles in an acetonitrile+water mixture, using cyclic voltammetry and controlled-potential coulometry. The results indicate that the o-quinone derived from quercetin participates in a Michael addition reaction with the benzenesulfinic acids to form the corresponding sulfonyl derivatives. The electrochemical synthesis of these derivatives has been

  3. Technology advancement of the electrochemical CO2 concentrating process

    NASA Technical Reports Server (NTRS)

    Schubert, F. H.; Woods, R. R.; Hallick, T. M.; Heppner, D. B.

    1977-01-01

    A five-cell, liquid-cooled advanced electrochemical depolarized carbon dioxide concentrator module was fabricated. The cells utilized the advanced, lightweight, plated anode current collector concept and internal liquid-cooling. The five cell module was designed to meet the carbon dioxide removal requirements of one man and was assembled using plexiglass endplates. This one-man module was tested as part of an integrated oxygen generation and recovery subsystem.

  4. ADVANCED OXIDATION PROCESS

    SciTech Connect

    Dr. Colin P. Horwitz; Dr. Terrence J. Collins

    2003-11-04

    The removal of recalcitrant sulfur species, dibenzothiophene and its derivatives, from automotive fuels is an integral component in the development of cleaner burning and more efficient automobile engines. Oxidative desulfurization (ODS) wherein the dibenzothiophene derivative is converted to its corresponding sulfoxide and sulfone is an attractive approach to sulfur removal because the oxidized species are easily extracted or precipitated and filtered from the hydrocarbon phase. Fe-TAML{reg_sign} activators of hydrogen peroxide (TAML is Tetra-Amido-Macrocyclic-Ligand) catalytically convert dibenzothiophene and its derivatives rapidly and effectively at moderate temperatures (50-60 C) and ambient pressure to the corresponding sulfoxides and sulfones. The oxidation process can be performed in both aqueous systems containing alcohols such as methanol, ethanol, or t-butanol, and in a two-phase hydrocarbon/aqueous system containing tert-butanol or acetonitrile. In the biphasic system, essentially complete conversion of the DBT to its oxidized products can be achieved using slightly longer reaction times than in homogeneous solution. Among the key features of the technology are the mild reaction conditions, the very high selectivity where no over oxidation of the sulfur compounds occurs, the near stoichiometric use of hydrogen peroxide, the apparent lack of degradation of sensitive fuel components, and the ease of separation of oxidized products.

  5. The hardness and wear of electrochemically grown tantalum oxide

    SciTech Connect

    Mulivor, A.W.; Mann, A.B.; Searson, P.C.; Weihs, T.P. [Johns Hopkins Univ., Baltimore, MD (United States). Materials Science and Engineering Dept.

    1998-12-31

    For several metallic systems, including tantalum, barrier (non-porous) oxide layers up to 200 nm thick can be grown quickly and efficiently using electrochemical techniques. The thickness of the oxide layer has been found to be linearly proportional to the voltage applied during the electrochemical growth process. These oxides can cause a substantial increase in both the hardness and wear-resistance of the surface. Ex-situ Micro and Nano indentation testing of the Ta/Ta{sub 2}O{sub 5} system has clearly shown that the indentation hardness increases with oxide thickness, even for indentation depths much greater than the oxide thickness. AFM imaging of indentations and analysis of nanoindentation curves suggests this increased hardness is due to the oxide impeding the pile-up of material at the edges of the indentation, which changes the geometry of the contact. Tribometer testing of various oxide thicknesses has shown that the oxide plays a similar role in preventing wear, specifically by preventing the transfer of material between the two contacting bodies and spreading the load over a greater area. Thus, the electrochemical growth of Ta{sub 2}O{sub 5} provides a convenient method for providing protective hard coatings.

  6. Advanced electrochemical concepts for NASA applications

    NASA Technical Reports Server (NTRS)

    Halpert, Gerald; Attia, Alan

    1989-01-01

    A Jet Propulsion Laboratory (JPL) survey of 23 electrochemical systems for space applications in which experts from universities, industry, and government participated is discussed. They recommended achievable specific energy for these systems and forecast the likelihood of their development of these systems by the year 1995, 2000, and 2005. The highest ranked systems for operation in planetary inner-orbit spacecraft included Na/beta-double prime-alumina/Z, where Z = S, FeCl2 or NiCl2, the upper plateau Li(Al)/FeS2 system, and the H2/O2 alkaline regenerative fuel cell. The achievable specific energy for these as operational batteries was estimated to be 130, 180 and 100 Wh/kg, respectively. For planetary outer-orbit and small geosynchronous (GEO) spacecraft Li/TiS2 (estimated 90 Wh/kg) was the choice.

  7. Silver ion catalyzed cerium(IV) mediated electrochemical oxidation of phenol in nitric acid medium

    Microsoft Academic Search

    Manickam Matheswaran; Subramanian Balaji; Sang Joon Chung; Il Shik Moon

    2007-01-01

    Mediated electrochemical oxidation (MEO) is one of the sustainable processes for organic pollutant destruction and has been employed for organic mineralization reactions by many researchers. In the MEO a metal ion capable of exhibiting redox behavior is oxidized from lower oxidation state to higher oxidation state by an electrochemical cell and subsequently used as an oxidant for mineralizing the toxic

  8. Nanoparticles in advanced oxidation processes

    Microsoft Academic Search

    Prashant V Kamat; Dan Meisel

    2002-01-01

    Photocatalysis using semiconductor nanoparticles as an advanced oxidation technique (AOT) has been a focus of research by a number of groups during the last two decades. The photocatalytic approach has been adopted successfully to develop self-cleaning glasses and air purification systems. Enhancing the photoconversion efficiency, maximizing the rate of degradation, and extending the photoresponse of the semiconductor catalyst into the

  9. Method of electrode fabrication for solid oxide electrochemical cells

    DOEpatents

    Jensen, Russell R. (Murrysville, PA)

    1990-01-01

    A process for fabricating cermet electrodes for solid oxide electrochemical cells by sintering is disclosed. First, a porous metal electrode is fabricated on a solid oxide cell, such as a fuel cell by, for example, sintering, and is then infiltrated with a high volume fraction stabilized zirconia suspension. A second sintering step is used to sinter the infiltrated zirconia to a high density in order to more securely attach the electrode to the solid oxide electrolyte of the cell. High performance fuel electrodes can be obtained with this process. Further electrode performance enhancement may be achieved if stabilized zirconia doped with cerium oxide, chromium oxide, titanium oxide, and/or praseodymium oxide for electronic conduction is used.

  10. Electrochemical and Structural Characterization of Nickel based Alloys Oxides

    NASA Astrophysics Data System (ADS)

    Hakiki, N. E.; Bubendorff, J. L.; Pirri, C.; Mechehoud, F.; Mehdaoui, A.; Belhadji, M.

    The electrochemical and structural characterization of thermally grown oxides formed on nickel based alloys (type Inconel 600 and 690) at 350 °C and during different time was performed by impedance measurements and near field microscopy combining atomic force microscopy (AFM) and scanning Kelvin probe force microscopy (SKPFM). The impedance results allow discussing the influence of the oxidation time on the capacitance and the resistance of the oxide films. The results obtained by near field microscopy technique show that the film formed during low oxidation time has a small grain size and also a small surface roughness. The values of grain sizes determined in both cases along x- and y-axis are practically the same indicating a spherical shape of oxide grains and are slightly different between oxides formed on type inconel 600 and 690.

  11. Zinc oxide nanostructures for electrochemical cortisol biosensing

    NASA Astrophysics Data System (ADS)

    Vabbina, Phani Kiran; Kaushik, Ajeet; Tracy, Kathryn; Bhansali, Shekhar; Pala, Nezih

    2014-05-01

    In this paper, we report on fabrication of a label free, highly sensitive and selective electrochemical cortisol immunosensors using one dimensional (1D) ZnO nanorods (ZnO-NRs) and two dimensional nanoflakes (ZnO-NFs) as immobilizing matrix. The synthesized ZnO nanostructures (NSs) were characterized using scanning electron microscopy (SEM), selective area diffraction (SAED) and photoluminescence spectra (PL) which showed that both ZnO-NRs and ZnO-NFs are single crystalline and oriented in [0001] direction. Anti-cortisol antibody (Anti-Cab) are used as primary capture antibodies to detect cortisol using electrochemical impedance spectroscopy (EIS). The charge transfer resistance increases linearly with increase in cortisol concentration and exhibits a sensitivity of 3.078 K?. M-1 for ZnO-NRs and 540 ?. M -1 for ZnO-NFs. The developed ZnO-NSs based immunosensor is capable of detecting cortisol at 1 pM. The observed sensing parameters are in physiological range. The developed sensors can be integrated with microfluidic system and miniaturized potentiostat to detect cortisol at point-of-care.

  12. Formaldehyde yields from methanol electrochemical oxidation on carbon-supported platinum catalysts

    Microsoft Academic Search

    Christina L. Childers; Huiliang Huang; Carol Korzeniewski

    1999-01-01

    The formation of formaldehyde during methanol electrochemical oxidation on supported Pt and Pt-Ru catalysts was investigated. While on solid platinum electrodes, the formaldehyde yields from methanol oxidation are near 30% at low potentials; the yields fall below 2% for methanol electrochemical oxidation on carbon-supported catalysts in Nafion. The lower formaldehyde yields, which result from more complete methanol oxidation, are believed

  13. Electrochromic polyaniline/graphite oxide nanocomposites with endured electrochemical energy storage

    E-print Network

    Guo, John Zhanhu

    Electrochromic polyaniline/graphite oxide nanocomposites with endured electrochemical energy February 2013 Keywords: Polyaniline nanocomposite film Electropolymerization Electrochromism a b s t r a c films for electrochromic displays and electrochemical energy storage devices applications were

  14. Direct electrochemical reduction of metal-oxides

    DOEpatents

    Redey, Laszlo I. (Downers Grove, IL); Gourishankar, Karthick (Downers Grove, IL)

    2003-01-01

    A method of controlling the direct electrolytic reduction of a metal oxide or mixtures of metal oxides to the corresponding metal or metals. A non-consumable anode and a cathode and a salt electrolyte with a first reference electrode near the non-consumable anode and a second reference electrode near the cathode are used. Oxygen gas is produced and removed from the cell. The anode potential is compared to the first reference electrode to prevent anode dissolution and gas evolution other than oxygen, and the cathode potential is compared to the second reference electrode to prevent production of reductant metal from ions in the electrolyte.

  15. Signal enhancement of electrochemical biosensors via direct electrochemical oxidation of silver nanoparticle labels coated with zwitterionic polymers.

    PubMed

    Geagea, R; Aubert, P-H; Banet, P; Sanson, N

    2015-01-01

    A new electrochemical label has been developed, which is made up of silver nanoparticles (AgNPs) coated with a mixture of zwitterionic and biotinylated zwitterionic polymers. These polymers improve colloidal stability in physiological medium and ensure biorecognition while direct electrochemical oxidation of silver nanoparticles strongly enhances the detection signal. The resulting hybrid nanomaterials are used as labels in the electrochemical sensing of avidin using sandwich assays elaborated using the biotin-avidin biorecognition system. PMID:25407013

  16. Electrochemical oxidation of phenol at boron-doped diamond electrode

    Microsoft Academic Search

    J. Iniesta; P. A. Michaud; M. Panizza; G. Cerisola; A. Aldaz; Ch. Comninellis

    2001-01-01

    The electrochemical oxidation of phenol at synthetic boron-doped diamond thin film electrode (BDD) has been studied in acid media by cyclic voltammetry, chronoamperometry and bulk electrolysis. The results have shown that in the potential region of water stability (E<2.3 V vs. SHE) they can occur direct electron transfer reactions on BDD surface that results in electrode fouling due to the

  17. Electrochemical Water-Splitting Based on Hypochlorite Oxidation.

    PubMed

    Macounová, Kate?ina Minhová; Simic, Nina; Ahlberg, Elisabet; Krtil, Petr

    2015-06-17

    Effective catalytic water-splitting can be electrochemically triggered in an alkaline solution of sodium hypochlorite. Hypochlorite oxidation on polycrystalline platinum yields ClO· radicals, which initiate a radical-assisted water-splitting, yielding oxygen, hydrogen peroxide, and protons. The efficiency of the O2 production corresponds to about two electrons per molecule of the produced O2 and is controlled primarily by the hypochlorite concentration and pH. PMID:26030185

  18. Electrochemical & Thermochemical Behavior of Cerium(IV) Oxide delta

    NASA Astrophysics Data System (ADS)

    Chueh, William C.

    The mixed-valent nature of nonstoichiometric ceria (CeO2-delta ) gives rise to a wide range of intriguing properties, such as mixed ionic and electronic conduction and oxygen storage. Surface and transport behavior in rare-earth (samaria) doped and undoped ceria were investigated, with particular emphasis on applications in electrochemical and thermochemical energy conversion processes such as fuel cells and solar fuel production. The electrochemical responses of bulk-processed ceria with porous Pt and Au electrodes were analyzed using 1-D and 2-D transport models to decouple surface reactions, near-surface transport and bulk transport. Combined experimental and numerical results indicate that hydrogen electro-oxidation and hydrolysis near open-circuit conditions occur preferentially over the ceria | gas interface rather than over the ceria | gas | metal interface, with the rate-limiting step likely to be either surface reaction or transport through the surface oxygen vacancy depletion layer. In addition, epitaxial thin films of ceria were grown on zirconia substrates using pulsed-laser deposition to examine electrocatalysis over well-defined microstructures. Physical models were derived to analyze the electrochemical impedance response. By varying the film thickness, interfacial and chemical capacitance were decoupled, with the latter shown to be proportional to the small polaron densities. The geometry of microfabricated metal current collectors (metal = Pt, Ni) was also systematically varied to investigate the relative activity of the ceria | gas and the ceria | metal | gas interfaces. The data suggests that the electrochemical activity of the metal-ceria composite is only weakly dependent on the metal due to the relatively high activity of the ceria | gas interface. In addition to electrochemical experiments, thermochemical reduction-oxidation studies were performed on ceria. It was shown that thermally-reduced ceria, upon exposure to H 2O and/or CO2, can be reoxidized to form H2, CO, and/or CH4. Analysis of gas evolution rates confirms that the kinetics of ceria oxidation by H2O and CO2 are dominated by surface reactions, rather than by ambipolar oxygen diffusion. Temperature-programmed oxidation experiments revealed that, even under thermodynamically favored conditions, carbonaceous species do not form on the surface of neat ceria, thereby giving a high CO selectivity when dissociating CO2. A scaled-up ceria-based solar reactor was designed and tested to demonstrate the feasibility of solar fuel production via thermochemical cycling.

  19. The electrochemical oxidation of organic selenides and selenoxides

    SciTech Connect

    Ryan, M.D.; Yau, J.; Hack, M. [Marquette Univ., Milwaukee, WI (United States). Dept. of Chemistry

    1997-06-01

    The electrochemical oxidation of alkyl and aryl selenides was investigated in acetonitrile. The oxidation of diphenyl selenide and di(4-methylphenyl) selenide led primarily to the formation of their respective selenoxides, which were identified by exhaustive coulometric oxidation and {sup 1}H and {sup 13}C analysis of the products. The selenoxide itself was not observed in the cyclic voltammetry of the selenide for two reasons: first, the protonation of the selenoxide by the acid formed from the reaction of water with the cation radical and second, the formation of a selenoxide hydrate. The formation of the hydrate with diphenyl selenoxide was verified by isolation of the dimethoxy derivative. In addition to the selenoxide, selenonium compounds, formed by the coupling of the oxidized material, were also observed. The alkyl selenides were generally oxidized at a lower potential than the aryl selenides. This trend is different from the sulfur analogues, where the aryl sulfides are easier to oxidize than their alkyl counterparts. As a result, the difference in their redox potentials is relatively small. These differences may occur because the oxidation of aryl sulfides is more likely to take place on the aromatic ring, which leads to a greater yield of the coupled products (about 100%) when compared to the selenide analogue.

  20. Fabrication of solid oxide fuel cell by electrochemical vapor deposition

    DOEpatents

    Riley, B.; Szreders, B.E.

    1988-04-26

    In a high temperature solid oxide fuel cell (SOFC), the deposition of an impervious high density thin layer of electrically conductive interconnector material, such as magnesium doped lanthanum chromite, and of an electrolyte material, such as yttria stabilized zirconia, onto a porous support/air electrode substrate surface is carried out at high temperatures (/approximately/1100/degree/ /minus/ 1300/degree/C) by a process of electrochemical vapor deposition. In this process, the mixed chlorides of the specific metals involved react in the gaseous state with water vapor resulting in the deposit of an impervious thin oxide layer on the support tube/air electrode substrate of between 20--50 microns in thickness. An internal heater, such as a heat pipe, is placed within the support tube/air electrode substrate and induces a uniform temperature profile therein so as to afford precise and uniform oxide deposition kinetics in an arrangement which is particularly adapted for large scale, commercial fabrication of SOFCs.

  1. Fabrication of solid oxide fuel cell by electrochemical vapor deposition

    DOEpatents

    Brian, Riley (Willimantic, CT); Szreders, Bernard E. (Oakdale, CT)

    1989-01-01

    In a high temperature solid oxide fuel cell (SOFC), the deposition of an impervious high density thin layer of electrically conductive interconnector material, such as magnesium doped lanthanum chromite, and of an electrolyte material, such as yttria stabilized zirconia, onto a porous support/air electrode substrate surface is carried out at high temperatures (approximately 1100.degree.-1300.degree. C.) by a process of electrochemical vapor deposition. In this process, the mixed chlorides of the specific metals involved react in the gaseous state with water vapor resulting in the deposit of an impervious thin oxide layer on the support tube/air electrode substrate of between 20-50 microns in thickness. An internal heater, such as a heat pipe, is placed within the support tube/air electrode substrate and induces a uniform temperature profile therein so as to afford precise and uniform oxide deposition kinetics in an arrangement which is particularly adapted for large scale, commercial fabrication of SOFCs.

  2. Physical and electrochemical study of cobalt oxide nano- and microparticles

    SciTech Connect

    Alburquenque, D. [Dpto. de Química de los Materiales, USACh, Av. L.B.O.‘Higgins 3363, 9170022 Santiago (Chile); Dpto. de Metalurgia, USACh, Av. Ecuador 3469, 9170124, Santiago (Chile); Vargas, E. [Dpto. de Física, USACh and CEDENNA, Av. Ecuador 3493, 9170124 Santiago (Chile); Dpto. de Metalurgia, USACh, Av. Ecuador 3469, 9170124, Santiago (Chile); Denardin, J.C.; Escrig, J. [Dpto. de Física, USACh and CEDENNA, Av. Ecuador 3493, 9170124 Santiago (Chile); Marco, J.F. [Instituto de Química Física “Rocasolano”, CSIC, c/Serrano 119, 28006 Madrid (Spain); Ortiz, J. [Dpto. de Química de los Materiales, USACh, Av. L.B.O.‘Higgins 3363, 9170022 Santiago (Chile); Gautier, J.L., E-mail: juan.gautier@usach.cl [Dpto. de Química de los Materiales, USACh, Av. L.B.O.‘Higgins 3363, 9170022 Santiago (Chile)

    2014-07-01

    Cobalt oxide nanocrystals of size 17–21 nm were synthesized by a simple reaction between cobalt acetate (II) and dodecylamine. On the other hand, micrometric Co{sub 3}O{sub 4} was prepared using the ceramic method. The structural examination of these materials was performed using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM and HRTEM). XRD studies showed that the oxides were pure, well-crystallized, spinel cubic phases with a-cell parameter of 0.8049 nm and 0.8069 nm for the nano and micro-oxide, respectively. The average particle size was 19 nm (nano-oxide) and 1250 ?m (micro-oxide). Morphological studies carried out by SEM and TEM analyses have shown the presence of octahedral particles in both cases. Bulk and surface properties investigated by X-ray photoelectron spectroscopy (XPS), point zero charge (pzc), FTIR and cyclic voltammetry indicated that there were no significant differences in the composition on both materials. The magnetic behavior of the samples was determined using a vibrating sample magnetometer. The compounds showed paramagnetic character and no coercivity and remanence in all cases. Galvanostatic measurements of electrodes formed with nanocrystals showed better performance than those built with micrometric particles. - Highlights: • Spinel Co{sub 3}O{sub 4} nanoparticles and microparticles with same structure but with different cell parameters, particle size and surface area were synthesized. • Oxide nanoparticles showed better electrochemical behavior than micrometric ones due to area effect.

  3. Electrochemical Characteristics of AZ31 Magnesium Alloys with Microarc Oxidation Coating Alycia Berman1

    E-print Network

    Zhou, Yaoqi

    Electrochemical Characteristics of AZ31 Magnesium Alloys with Microarc Oxidation Coating Alycia of Engineering and Technology, IUPUI When considering implantable biomaterials, one possible solution that has taken to find appropriate coatings. One possibility is microarc oxidation (MAO) coating. However

  4. Synergetic antibacterial activity of reduced graphene oxide and boron doped diamond anode in three dimensional electrochemical oxidation system.

    PubMed

    Qi, Xiujuan; Wang, Ting; Long, Yujiao; Ni, Jinren

    2015-01-01

    A 100% increment of antibacterial ability has been achieved due to significant synergic effects of boron-doped diamond (BDD) anode and reduced graphene oxide (rGO) coupled in a three dimensional electrochemical oxidation system. The rGO, greatly enhanced by BDD driven electric field, demonstrated strong antibacterial ability and even sustained its excellent performance during a reasonable period after complete power cut in the BDD-rGO system. Cell damage experiments and TEM observation confirmed much stronger membrane stress in the BDD-rGO system, due to the faster bacterial migration and charge transfer by the expanded electro field and current-carrying efficiency by quantum tunnel. Reciprocally the hydroxyl-radical production was eminently promoted with expanded area of electrodes and delayed recombination of the electron-hole pairs in presence of the rGO in the system. This implied a huge potential for practical disinfection with integration of the promising rGO and the advanced electrochemical oxidation systems. PMID:25994309

  5. Atmospheric and electrochemical oxidation of the surface of chalcopyrite (CuFeS 2)

    Microsoft Academic Search

    Q. Yin; G. H. Kelsall; D. J. Vaughan; K. E. R. England

    1995-01-01

    Atmospheric and electrochemical oxidation of the surface of chalcopyrite has been investigated using electrochemical techniques with subsequent surface analysis by X-ray photoelectron spectroscopy (XPS) and aqueous phase analysis by inductively coupled plasma-atomic emission spectrometry (ICPAES). The extent of atmospheric oxidation of chalcopyrite was assessed qualitatively by measuring the increase in the open circuit potential; quantitative estimation was made either by

  6. Electrochemically tunable thermal conductivity of lithium cobalt oxide.

    PubMed

    Cho, Jiung; Losego, Mark D; Zhang, Hui Gang; Kim, Honggyu; Zuo, Jianmin; Petrov, Ivan; Cahill, David G; Braun, Paul V

    2014-01-01

    Using time-domain thermoreflectance, the thermal conductivity and elastic properties of a sputter deposited LiCoO2 film, a common lithium-ion cathode material, are measured as a function of the degree of lithiation. Here we report that via in situ measurements during cycling, the thermal conductivity of a LiCoO2 cathode reversibly decreases from ~5.4 to 3.7 W m(-1) K(-1), and its elastic modulus decreases from 325 to 225 GPa, as it is delithiated from Li1.0CoO2 to Li0.6CoO2. The dependence of the thermal conductivity on lithiation appears correlated with the lithiation-dependent phase behaviour. The oxidation-state-dependent thermal conductivity of electrolytically active transition metal oxides provides opportunities for dynamic control of thermal conductivity and is important to understand for thermal management in electrochemical energy storage devices. PMID:24892640

  7. Electrochemical formation of a composite polymer-aluminum oxide film

    NASA Astrophysics Data System (ADS)

    Runge-Marchese, Jude Mary

    1997-10-01

    The formation of polymer films through electrochemical techniques utilizing electrolytes which include conductive polymer is of great interest to the coatings and electronics industries as a means for creating electrically conductive and corrosion resistant finishes. One of these polymers, polyamino-benzene (polyaniline), has been studied for this purpose for over ten years. This material undergoes an insulator-to-metal transition upon doping with protonic acids in an acid/base type reaction. Review of prior studies dealing with polyaniline and working knowledge of aluminum anodization has led to the development of a unique process whereby composite polymer-aluminum oxide films are formed. The basis for the process is a modification of the anodizing electrolyte which results in the codeposition of polyaniline during aluminum anodization. A second process, which incorporates electrochemical sealing of the anodic layer with polyaniline was also developed. The formation of these composite films is documented through experimental processing, and characterized by way of scientific analysis and engineering tests. Analysis results revealed the formation of unique dual phase anodic films with fine microstructures which exhibited full intrusion of the columnar aluminum oxide structure with polyaniline, indicating the polymer was deposited as the metal oxidation proceeded. An aromatic amine derivative of polyaniline with aluminum sulfate was determined to be the reaction product within the aluminum oxide phase of the codeposited films. Scientific characterization determined the codeposition process yields completely chemically and metallurgically bound composite films. Engineering studies determined the films, obtained through a single step, exhibited superior wear and corrosion resistance to conventionally anodized and sealed films processed through two steps, demonstrating the increased manufacturing process efficiency that can be realized with the modification of the conventional anodization process.

  8. Redox deposition of nanoscale metal oxides on carbon for next-generation electrochemical capacitors.

    PubMed

    Sassin, Megan B; Chervin, Christopher N; Rolison, Debra R; Long, Jeffrey W

    2013-05-21

    Transition metal oxides that mix electronic and ionic conductivity are essential active components of many electrochemical charge-storage devices, ranging from primary alkaline cells to more advanced rechargeable Li-ion batteries. In these devices, charge storage occurs via cation-insertion/deinsertion mechanisms in conjunction with the reduction/oxidation of metal sites in the oxide. Batteries that incorporate such metal oxides are typically designed for high specific energy, but not necessarily for high specific power. Electrochemical capacitors (ECs), which are typically composed of symmetric high-surface-area carbon electrodes that store charge via double-layer capacitance, deliver their energy in time scales of seconds, but at much lower specific energy than batteries. The fast, reversible faradaic reactions (typically described as "pseudocapacitance") of particular nanoscale metal oxides (e.g., ruthenium and manganese oxides) provide a strategy for bridging the power/energy performance gap between batteries and conventional ECs. These processes enhance charge-storage capacity to boost specific energy, while maintaining the few-second timescale of the charge-discharge response of carbon-based ECs. In this Account, we describe three examples of redox-based deposition of EC-relevant metal oxides (MnO2, FeOx, and RuO2) and discuss their potential deployment in next-generation ECs that use aqueous electrolytes. To extract the maximum pseudocapacitance functionality of metal oxides, one must carefully consider how they are synthesized and subsequently integrated into practical electrode structures. Expressing the metal oxide in a nanoscale form often enhances electrochemical utilization (maximizing specific capacitance) and facilitates high-rate operation for both charge and discharge. The "wiring" of the metal oxide, in terms of both electron and ion transport, when fabricated into a practical electrode architecture, is also a critical design parameter for achieving characteristic EC charge-discharge timescales. For example, conductive carbon must often be combined with the poorly conductive metal oxides to provide long-range electron pathways through the electrode. However, the ad hoc mixing of discrete carbon and oxide powders into composite electrodes may not support optimal utilization or rate performance. As an alternative, nanoscale metal oxides of interest for ECs can be synthesized directly on the surfaces of nanostructured carbons, with the carbon surface acting as a sacrificial reductant when exposed to a solution-phase, oxidizing precursor of the desired metal oxide (e.g., MnO4(-) for MnO2). These redox deposition methods can be applied to advanced carbon nanoarchitectures with well-designed pore structures. These architectures promote effective electrolyte infiltration and ion transport to the nanoscale metal oxide domains within the electrode architecture, which further enhances high-rate operation. PMID:22380783

  9. A novel advanced oxidation process—wet electro-catalytic oxidation for high concentrated organic wastewater treatment

    Microsoft Academic Search

    QiZhou Dai; MingHua Zhou; LeCheng Lei; XingWang Zhang

    2007-01-01

    A novel advanced oxidation process—wet electrocatalytic oxidation (WEO) was studied with p-nitrophenol as model pollutant and ?-PbO2 electrode as the anode. Compared with the effect of the individual wet air oxidation (WAO) and electrochemical oxidation\\u000a (EO), the effect of WEO showed synergistic effect on COD removal under the conditions of temperature 160C, C=1000 mgL?1, \\u000a $$P_{N_2 } = 0.50$$\\u000a MPa, \\u000a $$P_{O_2

  10. Electrochemical assessment of electrochemical oxidation stability of self-assembled monolayers on gold and preparation of binary self-assembled monolayers on gold

    Microsoft Academic Search

    Yu Chen; Chen Yang; Feng-Bin Wang

    2010-01-01

    Binary thiolates self-assembled monolayers (SAMs) on gold have been prepared efficiently by using an electrochemical oxidation combining with replacement reaction method. The electrochemical results show that both the SAMs of mercaptoacetic acid (MAA) and 1-dodecanethiol (DT) on gold surface are oxidized at certain anodic potentials (noting: it is not oxidative redeposition of alkanethiolate monolayers on gold surface), and the degree

  11. Electrochemical oxidation of carbon fibers: Properties, surface chemistry and morphology

    NASA Astrophysics Data System (ADS)

    Jiang, Wenbo

    1999-10-01

    A series of PAN-based T300 carbon fibers was continuously, electrochemically oxidized in aqueous and organic media. A 30% fiber weight loss was obtained at an extent of oxidation of 10,600 C/g. Acidic functional groups were produced on fiber surfaces in amounts from 0 to 2640 mumol/g as the extent of oxidation increased from 0 to 10600 C/g. These surface functions were further reacted with diethylenetriamine to introduce amine functions onto fibers. The oxidation extended far deeper than the XPS detection limit (<100 A). N 2 BET at 77K gave very low fiber specific surface area in contrast to CO2 DR measurements at 273 K which confirmed large increases in surface area with oxidation. No heavy damage or macro-/mesopores were found in scanning electron micrographs. An ultramicropore structure was characterized by the CO2 DR method combined with nonlocal density functional theory. The average pore diameter was about 1.2 nm with a dominant pore diameter of 0.4 nm. CCl4, methylene blue, I2, AgNO3, and Ni(NO3)2 adsorption studies were performed. A pH-dependent swelling model was discussed. In basic media, a solvation/swelling process allows small molecules to penetrate the microporous channels and react with fiber functional groups. A remote site silver reduction/adsorption model was confirmed based upon high AgNO3 adsorption and qualitative experiments. Single filament breaking and fragmentation tests and fiber/epoxy composite mechanical tests were conducted. Fiber/epoxy matrix adhesion was improved by oxidation although the fiber tensile strength decreased. Post-heat treatment causes further weight loss and the loss of oxygen-containing surface functional groups.

  12. Effects of Electrochemical-Deposition Method on the Capacitive Behavior of Molybdenum Oxide

    Microsoft Academic Search

    Shokufeh Moghiminia; Hossein Farsi; Heidar Raissy

    Thin films of transitional metal oxides are interesting materials for electrochemical energy storage devices such as supercapacitors, batteries and electrochromic systems (1). This character is caused by small ionic adsorption or intercalation\\/deintercalation reactions. The common face of transition metal oxides is their variable valences. It seems molybdenum oxide be a suitable material for this proposes due to its different oxide

  13. Bismuth oxide coated amorphous manganese dioxide for electrochemical capacitors

    NASA Astrophysics Data System (ADS)

    Li, Xiaofeng; Zhang, Linsen; Dong, Huichao; Xia, Tongchi; Huang, Zhigang

    2015-05-01

    With MnSO4, NaOH and K2S2O8 as the raw materials, the amorphous and ?-type manganese dioxide (MnO2) is separately prepared by using different chemical precipitation-oxidation methods. The results of charge-discharge and electrochemical impedance spectroscopy (EIS) tests show that (i) the specific capacitance of the amorphous MnO2 reaches to 301.2 F g-1 at a current density of 200 mA g-1 and its capacitance retention rate after 2000 cycles is 97%, which is obviously higher than 250.8 F g-1 and 71% of the ?-type one, respectively; (ii) good electrochemical capacitance properties of the amorphous MnO2 should be contributed to easy insertion/extraction of ions within the material; (iii) when 5 wt% Bi2O3 is coated on the amorphous MnO2, its specific capacitance increases to 352.8 F g-1 and the capacitance retention rate is 90% after 2000 cycles.

  14. Corrosion mechanism of cuprous oxide/iodide solar electrochemical cell

    NASA Astrophysics Data System (ADS)

    Tennakone, K.; Gurunnanselage, W.; Dharmaratne, D.; Jayewardena, S. C.

    1982-01-01

    Mechanisms for cuprous oxide corrosion in an iodide solution are investigated in light of the importance of instability effects arising from semiconductor electrode corrosion in solar electrochemical cells. Experiments involved the use of a potassium iodide solution containing a trace of iodine as the redox electrolyte, with a cuprous oxide-coated copper plate as the photocathode and a copper window coated with cupric sulphide as the counterelectrode. Measurement of the time dependence of the short circuit current at constant illumination intensity reveals it to undergo a rapid decay accompanied by the formation of a cuprous iodide-cupric oxide deposit on the photocathode surface. The region surrounding a circular patch of light focussed on the photocathode is found to exhibit CuO and CuI deposits signalling corrosion in the anodic region surrounding the cathodic spot. Measurements of the time dependence of the open circuit voltage furthermore indicate that the saturation voltage decays with time, due to short circuiting in the photocathode between anodic and cathodic regions.

  15. Mechanism of p-substituted phenol oxidation at a Ti4O7 reactive electrochemical membrane.

    PubMed

    Zaky, Amr M; Chaplin, Brian P

    2014-05-20

    This research investigated the removal mechanisms of p-nitrophenol, p-methoxyphenol, and p-benzoquinone at a porous Ti4O7 reactive electrochemical membrane (REM) under anodic polarization. Cross-flow filtration experiments and density functional theory (DFT) calculations indicated that p-benzoquinone removal was primarily due to reaction with electrochemically formed OH(•), while the dominant removal mechanism of p-nitrophenol and p-methoxyphenol was a function of the anodic potential. At low anodic potentials (1.7-1.8 V/SHE), p-nitrophenol and p-methoxyphenol were removed primarily by an electrochemical adsorption/polymerization mechanism on the REM. Increasing anodic potentials (1.9-3.2 V/SHE) resulted in the electroassisted adsorption mechanism contributing far less to p-methoxyphenol removal compared to p-nitrophenol. DFT calculations indicated that an increase in anodic potential resulted in a shift in p-methoxyphenol removal from a 1e(-) direct electron transfer (DET) reaction that resulted in radical formation and significant adsorption/polymerization, to a 2e(-) DET reaction that formed nonadsorbing products (i.e., p-benzoquinone). However, the anodic potentials were too low for the 2e(-) DET reaction to be thermodynamically favorable for p-nitrophenol. The decreased COD adsorption for p-nitrophenol at higher anodic potentials was attributed to reaction of soluble/adsorbed organics with OH(•). These results provide the first mechanistic explanation for p-substituted phenolic compound removal during advanced electrochemical oxidation processes. PMID:24766505

  16. A new approach to deep desulfurization of gasoline by electrochemically catalytic oxidation and extraction

    Microsoft Academic Search

    Wenbo Wang; Shujun Wang; Yuanhao Wang; Hongyan Liu; Zhenxin Wang

    2007-01-01

    In order to further reduce the sulfur content in gasoline, a new desulfurization process for gasoline was obtained by means of electrochemically catalytic oxidation and extraction with an electrochemical fluidized-bed reactor. The particle group anode was activated carbon-supported lead dioxide (?-PbO2\\/C). The electrolyte was aqueous NaOH solution, and copper pillar was cathode in the electrochemical reactions. The ?-PbO2\\/C particle group

  17. Desulfurization of gasoline by a new method of electrochemical catalytic oxidation

    Microsoft Academic Search

    Wenbo Wang; Shujun Wang; Hongyan Liu; Zhenxin Wang

    2007-01-01

    A new deep desulfurization process for gasoline was obtained by means of electrochemical catalytic oxidation with an electrochemical fluidized-bed reactor on particle group anode. The particle group anode was activated carbon-supported cerium dioxide (CeO2\\/C), and the electrolyte was aqueous cerium nitrate solution, and copper pillar was cathode in the electrochemical reactions. The CeO2\\/C particle group anode could remarkably accelerate the

  18. Bromate formation in advanced oxidation processes

    Microsoft Academic Search

    Urs von Gunten; Auguste Bruchet; Eliane Costentin

    1996-01-01

    Bromate formation in conventional ozonation and advanced oxidation processes combining ozone and hydrogen peroxide was investigated at five water treatment plants. Before ozonation, bromide concentrations ranged from 35 to 130 ?g\\/L. Bromate formed during the ozonation step varied from < 2 to 42 ?g\\/L. In general, oxidation leads to higher bromate concentrations when compared with a conventional ozonation process, if

  19. Improved electrochemical biosensor response via metal oxide pre-oxidation of chemical interferents

    NASA Astrophysics Data System (ADS)

    Houseknecht, Jamie G.; Tapsak, Mark A.

    2007-09-01

    Typical biological samples are inherently complicated. They may contain a myriad of compounds that are electroactive at the same potential as that used in many electrochemical biosensors. Therefore, a biosensor design feature must be included that either eliminates or blocks the interferents from generating false positive signals. The ability to use an insoluble compound, that of MnO II, in order to oxidize interferents such as ascorbic acid, acetaminophen and uric acid, was investigated in a prototype sensor system at a bias potential of 0.6 V versus Ag/AgCl. Unlike previous work with these materials, a difference between the ability for the metal oxide to oxidize the interferents was observed. Most effective was the capability of MnO II to oxidize uric acid. Alternatively, the MnO II had little effect on acetaminophen. The study is both introduced and results are discussed within the context of an implantable glucose sensor.

  20. Writing nanopatterns with electrochemical oxidation on redox responsive organometallic multilayers by AFM.

    PubMed

    Song, Jing; Hempenius, Mark A; Jing Chung, Hong; Julius Vancso, G

    2015-06-14

    Nanoelectrochemical patterning of redox responsive organometallic poly(ferrocenylsilane) (PFS) multilayers is demonstrated by electrochemical dip pen lithography (EDPN). Local electrochemical oxidation and Joule heating of PFS multilayers from the tip are considered as relevant mechanisms related to structure generation. The influence of applied bias potential, tip velocity, and multilayer thickness on the pattern height and width were investigated. PMID:25939476

  1. Electrochemically Reduced Water Protects Neural Cells from Oxidative Damage

    PubMed Central

    Hamasaki, Takeki; Kinjo, Tomoya; Nakamichi, Noboru; Teruya, Kiichiro; Kabayama, Shigeru

    2014-01-01

    Aging-related neurodegenerative disorders are closely associated with mitochondrial dysfunction and oxidative stresses and their incidence tends to increase with aging. Brain is the most vulnerable to reactive species generated by a higher rate of oxygen consumption and glucose utilization compared to other organs. Electrochemically reduced water (ERW) was demonstrated to scavenge reactive oxygen species (ROS) in several cell types. In the present study, the protective effect of ERW against hydrogen peroxide (H2O2) and nitric oxide (NO) was investigated in several rodent neuronal cell lines and primary cells. ERW was found to significantly suppress H2O2 (50–200??M) induced PC12 and SFME cell deaths. ERW scavenged intracellular ROS and exhibited a protective effect against neuronal network damage caused by 200??M H2O2 in N1E-115 cells. ERW significantly suppressed NO-induced cytotoxicity in PC12 cells despite the fact that it did not have the ability to scavenge intracellular NO. ERW significantly suppressed both glutamate induced Ca2+ influx and the resulting cytotoxicity in primary cells. These results collectively demonstrated for the first time that ERW protects several types of neuronal cells by scavenging ROS because of the presence of hydrogen and platinum nanoparticles dissolved in ERW. PMID:25383141

  2. Electrochemical investigation of Mn4O4-cubane water-oxidizing clustersw Robin Brimblecombe,ab

    E-print Network

    Lawson, Catherine L.

    of the most important catalysts found in nature, the water-oxidizing complex of photosystem II. We describe the attachment of the catalysts to conductive surfaces for direct electrochemical oxidation or to photoanodes. In a recent study, we described the sustained, catalytic, light- driven electro-oxidation of water by a bio

  3. Electropolymerized Polyaniline Stabilized Tungsten Oxide Nanocomposite Films: Electrochromic Behavior and Electrochemical

    E-print Network

    Guo, John Zhanhu

    Electropolymerized Polyaniline Stabilized Tungsten Oxide Nanocomposite Films: Electrochromic. The optical properties and electrochemical capacitive behaviors of the composite films for electrochromic (EC electrochromism at both positive and negative potentials arising from PANI and WO3, respectively. A coloration

  4. Simultaneous removal of nitrogen oxides and diesel soot particulate in nano-structured electrochemical reactor

    Microsoft Academic Search

    Koichi Hamamoto; Yoshinobu Fujishiro; Masanobu Awano

    2006-01-01

    Simultaneous decomposition of nitrogen oxides (NOx) and solid state graphite particles were carried out using a 8 mol% Y2O3 doped ZrO2 (YSZ) based electrochemical reactor with a nano-structured NOx selective multilayer cathode and an oxidative porous anode. The ceramic electrochemical cell was prepared by screen-printing a Pt and a NiO–YSZ pastes as cathode layers and a 12 CaO7Al2O3–Pt paste as an anode

  5. Advances in the SERI-DOE electrochemical photovoltaic cell program

    NASA Astrophysics Data System (ADS)

    Wallace, W.; Noufi, R.; Deb, S.

    1981-05-01

    The electrochemical photovoltaic cell program to evaluate the photovoltaic energy conversion efficiency, stability and storage potential of amorphous and polycrystalline semiconductor/electrolyte systems is described. Technologies capable of the conversion of light energy into electrical energy either directly in regenerative electrochemical photovoltaic devices or indirectly in overall regenerative cyclic systems incorporating storage are described. The goal of the program is to develop and demonstrate the viability of low cost electrochemical photovoltaic cells competitive with solid state photovoltaic devices and photoelectrochemical storage systems competitive with battery connected photovoltaic array storage.

  6. In situ chemical synthesis of ruthenium oxide/reduced graphene oxide nanocomposites for electrochemical capacitor applications.

    PubMed

    Kim, Ji-Young; Kim, Kwang-Heon; Yoon, Seung-Beom; Kim, Hyun-Kyung; Park, Sang-Hoon; Kim, Kwang-Bum

    2013-08-01

    An in situ chemical synthesis approach has been developed to prepare ruthenium oxide/reduced graphene oxide (RGO) nanocomposites. It is found that as the C/O ratio increases, the number density of RuO2 nanoparticles decreases, because the chemical interaction between the Ru ions and the oxygen-containing functional groups provides anchoring sites where the nucleation of particles takes place. For electrochemical capacitor applications, the microwave-hydrothermal process was carried out to improve the conductivity of RGO in RuO2/RGO nanocomposites. The significant improvement in capacitance and high rate capability might result from the RuO2 nanoparticles used as spacers that make the interior layers of the reduced graphene oxide electrode available for electrolyte access. PMID:23765196

  7. Electron beam deposition of amorphous manganese oxide thin film electrodes and their predominant electrochemical properties

    NASA Astrophysics Data System (ADS)

    Sarkar, Abhimanyu; Satpati, Ashis Kumar; Rao, Pritty; Kumar, Sanjiv

    2015-06-01

    Electron beam evaporated manganese oxide films display excellent electrochemical properties on post deposition oxidative annealing in air. The films annealed below 573 K are amorphous, exhibit minor deficiency in oxygen and are characterized by a specific discharge capacitance of 398 F g-1 at a discharge current of 1.1 A g-1 and 236 F g-1 at a discharge current of 5.5 A g-1. In terms of stability, these films retain 99.6% of their specific capacitance even after 400 cycles. The electrochemical properties of these films are explained in terms of their structure and composition which have been measured by X-ray diffraction and proton elastic backscattering spectrometry. In addition, the electrochemical properties are influenced by their morphology; the oxidatively annealed films contain nanometric, spherical and elongated grains which acquire extensive networking during electrochemical measurements.

  8. Oxidation of alloys for advanced steam turbines

    SciTech Connect

    Holcomb, Gordon R.; Covino, Bernard S., Jr.; Bullard, Sophie J.; Cramer, Stephen D.; Ziomek-Moroz, M.

    2005-01-01

    Ultra supercritical (USC) power plants offer the promise of higher efficiencies and lower emissions. Current goals of the U.S. Department of Energy’s Advanced Power Systems Initiatives include coal generation at 60% efficiency, which would require steam temperatures of up to 760°C. This research examines the steamside oxidation of advanced alloys for use in USC systems, with emphasis placed on alloys for high- and intermediate-pressure turbine sections.

  9. Improved preparative electrochemical oxidation of d-glucose to d-glucaric acid

    Microsoft Academic Search

    Mathias Ibert; Patrick Fuertès; Nabyl Merbouh; Catherine Fiol-Petit; Christian Feasson; Francis Marsais

    2010-01-01

    The 2,2,6,6-tetramethyl-1-piperidinyloxy free radical (TEMPO) mediated electrochemical oxidation of d-glucose to d-glucaric acid on a synthetically useful scale is reported. Using TEMPO and a graphite felt anode combined with a stainless steel cathode, d-glucose was oxidized under different conditions (pH, temperature, co-oxidant), and the reaction outcomes were analyzed. Optimized conditions for such oxidation are provided along with few new interesting

  10. Electrochemical oxidation processes on Ni electrodes in propylene carbonate containing various electrolyte salts

    SciTech Connect

    Kanamura, Kiyoshi; Toriyama, Shigetaka; Shiraishi, Soshi; Takehara, Zenichiro [Kyoto Univ. (Japan)

    1996-08-01

    Electrochemical oxidation processes on Ni electrodes in propylene carbonate electrolytes were investigated by using cyclic voltammetry, X-ray photoelectron spectroscopy, and in situ Fourier transform infrared spectroscopy. The results of these analyses suggest that Ni electrodes, electrolyte salts, and solvent are oxidized at a greater anodic potential than 4.2 V vs. Li/Li{sup +}. When propylene carbonate (PC) electrolyte containing LiAsF{sub 6}, LiBF{sub 4}, or LiPF{sub 6} was used, a large amount of Ni fluorides and oxides formed on the Ni electrodes and became inactive in response to Ni oxidation. The Fourier transform infrared measurement showed that the oxidation of PC in these electrolytes is enhanced by the formation of the above-mentioned Ni compounds in the first scan. On the other hand, inactivation was not observed for PC electrolytes containing LiCF{sub 3}SO{sub 3}. Correspondingly, the oxidation of PC in this electrolyte was more suppressed than that in the other three electrolytes. When PC containing LiClO{sub 4} was used as an electrolyte, the formation of Ni oxides was observed as well as the active oxidation of PC. This result indicates that Ni oxides are actively involved in the electrochemical oxidation of PC. Thus, electrochemical oxidation processes on Ni electrodes in various PC electrolytes can be explained by the oxidation of Ni electrodes in association with anion decomposition, which determines type of products formed on Ni electrodes.

  11. HANDBOOK ON ADVANCED NONPHOTOCHEMICAL OXIDATION PROCESSES

    EPA Science Inventory

    The purpose of this handbook is to summarize commercial-scale system performance and cost data for advanced nonphotochemical oxidation (ANPO) treatment of contaminated water, air, and soil. Similar information from pilot-and bench-scale evaluations of ANPO processes is also inclu...

  12. Nanocrystals of Uranium Oxide: Controlled Synthesis and Enhanced Electrochemical Performance of Hydrogen Evolution by Ce Doping.

    PubMed

    Hu, Shi; Li, Haoyi; Liu, Huiling; He, Peilei; Wang, Xun

    2015-06-01

    A preliminary study of the growth of 0D, 1D, and 2D nanostructures of uranium oxides with feature sizes from several nanometers down to 1 nm are presented. Cerium is successfully doped into these oxides and its influence on the growth dynamics and electrochemical performance investigated. PMID:25627103

  13. Status of test results of electrochemical organic oxidation of a tank 241-SY-101 simulated waste

    SciTech Connect

    Colby, S.A.

    1994-06-01

    This report presents scoping test results of an electrochemical waste pretreatment process to oxidize organic compounds contained in the Hanford Site`s radioactive waste storage tanks. Electrochemical oxidation was tested on laboratory scale to destroy organics that are thought to pose safety concerns, using a nonradioactive, simulated tank waste. Minimal development work has been applied to alkaline electrochemical organic destruction. Most electrochemical work has been directed towards acidic electrolysis, as in the metal purification industry, and silver catalyzed oxidation. Alkaline electrochemistry has traditionally been associated with the following: (1) inefficient power use, (2) electrode fouling, and (3) solids handling problems. Tests using a laboratory scale electrochemical cell oxidized surrogate organics by applying a DC electrical current to the simulated tank waste via anode and cathode electrodes. The analytical data suggest that alkaline electrolysis oxidizes the organics into inorganic carbonate and smaller carbon chain refractory organics. Electrolysis treats the waste without adding chemical reagents and at ambient conditions of temperature and pressure. Cell performance was not affected by varying operating conditions and supplemental electrolyte additions.

  14. Synthesis of reduced graphene oxide and its electrochemical sensing of 4-nitrophenol

    NASA Astrophysics Data System (ADS)

    Giribabu, K.; Suresh, R.; Manigandan, R.; Vijayalakshmi, L.; Stephen, A.; Narayanan, V.

    2013-02-01

    Reduced graphene oxide (RGO) nanosheets were synthesized by chemical reduction followed by Hummer's method. The synthesized RGO nanosheets were characterized by XRD, HR-TEM and FT-IR spectroscopy. Cyclic voltammetry (CV) was used to study the electrochemical sensing of 4-nitrophenol (4-NP). The as synthesized RGO nanosheets modified glassy carbon electrode (RGO/GCE) showed a good electrochemical sensing property when compared with bare GCE.

  15. Evaluating the electrochemical capacitance of surface-charged nanoparticle oxide coatings.

    PubMed

    Leonard, Kevin C; Suyama, Wendy E; Anderson, Marc A

    2012-04-17

    While transition metal oxides have been thoroughly investigated as coatings for electrochemical capacitors due to their pseudocapacitance, little work has been done investigating other oxide coatings. There exists a whole class of nanoporous oxides typically synthesized by sol-gel chemistry techniques that have very high differential capacitance. This high differential capacitance has been attributed to the surface potential of these materials and the close approach of counterions near the surface of these oxides. This study focuses on investigating the electrochemical capacitance of non-transition metal oxide nanoparticle coatings when deposited on supporting electrodes. Here, we show that, by adding coatings of SiO(2), AlOOH, TiO(2), and ZrO(2) nanoparticles to graphite support electrodes, we can increase the electrochemical capacitance. We also show that the measured electrochemical capacitance of these oxide-coated electrodes directly relates to the electrophoretic mobility of these materials with the lowest values in capacitance occurring at or near the respective isoelectric pH (pH(IEP)) of each oxide. PMID:22428877

  16. Advanced Oxidation Technology for Pulp Mill Effluent

    E-print Network

    Hart, J. R.

    is often required. Advanced oxidation is one technology which has application to bleached Kraft pulp effluent, principally for color reduction. INTRODUCTION The composition of wood (bone dry) is approximately 50% cellulose, 30% hemicelluloses... toxic. Of particular interest in the Study (1) to be presented here, is that some of the effluent streams subjected to treatment, originated from a bleaching process which used chlorine and chlorine dioxide as bleaching agents. When...

  17. Electrochemical oxidation of berberine and mass spectrometric identification of its oxidation products.

    PubMed

    Skopalová, Jana; Vacek, Jan; Papoušková, Barbora; Jirovský, David; Maier, Vít?zslav; Ranc, Václav

    2012-10-01

    Electrochemical oxidation of the isoquinoline alkaloid berberine in aqueous medium was studied by cyclic and differential pulse voltammetry at a glassy carbon electrode (GCE). Two anodic peaks of the quaternary form of berberine were observed at +1.2V and +1.4V (vs. SCE) in acidic and neutral solutions. When the anodic polarization exceeded the value of +1.1 V, the redox active film is formed on the GCE surface. The formation of adsorbed film was well-documented by quasireversible redox couple at +0.25 V which was studied in redox cycling experiments. In alkaline medium, a new anodic peak at +0.5 V appeared due to oxidation of berberine pseudobase to 8-oxoberberine. Solutions of berberine at different pH were subjected to controlled potential electrolysis on platinum gauze electrode and analyzed using liquid chromatography (HPLC) equipped with electrospray ionization/quadrupole time-of-flight mass spectrometry. The main water soluble monomeric product of berberine oxidation under physiological-near experimental conditions, OP1, was identified as demethyleneberberine cation (2,3-dihydroxy-9,10-dimethoxy-5,6-dihydroisoquinolino[3,2-a]isoquinolin-7-ium). PMID:21963270

  18. Synthesis and electrochemical behavior of nanostructured cauliflower-shape Co-Ni/Co-Ni oxides composites

    SciTech Connect

    Gupta, Vinay [Art, Science and Technology Center for Cooperative Research, Kyushu University, Kasuga-shi, Fukuoka, Kyushu 816-8580 (Japan); Japan Science and Technology Agency, Kawaguchi-shi, Saitama 332-0012 (Japan)], E-mail: drvinaygupta@netscape.net; Kawaguchi, Toshikazu; Miura, Norio [Art, Science and Technology Center for Cooperative Research, Kyushu University, Kasuga-shi, Fukuoka, Kyushu 816-8580 (Japan)

    2009-01-08

    Nanostructured Co-Ni/Co-Ni oxides were electrochemically deposited onto stainless steel electrode by electrochemical method and characterized for their structural and supercapacitive properties. The SEM images indicated that the obtained Co-Ni/Co-Ni oxides had cauliflower-type nanostructure. The X-ray diffraction pattern showed the formation of Co{sub 3}O{sub 4}, NiO, Co and Ni. The EDX elemental mapping images indicated that Ni, Co and O are distributed uniformly. The deposited Co-Ni/Co-Ni oxides showed good supercapacitive characteristics with a specific capacitance of 331 F/g at 1 mA/cm{sup 2} current density in 1 M KOH electrolyte. A mechanism of the formation of cauliflower-shape Co-Ni/Co-Ni oxides was proposed. A variety of promising applications in the fields such as energy storage devices and sensors can be envisioned from Co-Ni/Co-Ni oxides.

  19. Electrochemical oxidation of wine polyphenols in the presence of sulfur dioxide.

    PubMed

    Makhotkina, Olga; Kilmartin, Paul A

    2013-06-12

    Electrochemical oxidation of three representative wine polyphenols (catechin, caffeic acid, and quercetin) in the presence of sulfur dioxide in a model wine solution (pH = 3.3) was investigated. The oxidation was undertaken using chronoamperometry at a rotating glassy carbon rod electrode, and the reaction products were characterized by HPLC-MS. The mechanism of electrochemical oxidation of polyphenols in the presence of sulfur dioxide was proposed to be an ECEC mechanism. The polyphenols first underwent a one-electron oxidation to a semiquinone radical, which can be reduced back to the original polyphenol by sulfur dioxide, or further oxidized to the quinone form. In the cases of caffeic acid and catechin, the quinone combined with sulfur dioxide and produced new derivatives. The quercetin quinone underwent further chemical transformations, producing several new compounds. The proposed mechanisms were confirmed by digital simulation of cyclic voltammograms. PMID:23692398

  20. Characterization of advanced oxidation regenerated GACs

    SciTech Connect

    Singh, J. [Pennsylvania State Univ., Erie, PA (United States). Dept. of Civil and Environmental Engineering; Cannon, F.S. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Civil and Environmental Engineering

    1995-11-01

    Industrial and manufacturing processes that employ organic solvents, such as pharmaceutical production, spray booth coating applications, and petrochemical processing, constitute a major source of airborne volatile organic contaminants (VOCs) and hazardous air pollutants (HAPs). VOCs released into the atmosphere react with sunlight to create photochemical smog, oxidants and other pollutants, all of which are considered harmful to animal and plant life. There is thus a need for effective air pollution remediation technologies for such facilities. This paper explores the effects of regeneration by means of advanced oxidation involving UV and ozone, on several properties of granular activated carbons (GACs). The effects of reduction in surface areas and pore volumes, and surface oxidation due to this process of regeneration, on adsorption capacities of some model VOCs is investigated.

  1. Electrochemical oxidation of 2,4,5-trichlorophenoxyacetic acid by metal-oxide-coated Ti electrodes.

    PubMed

    Maharana, Dusmant; Xu, Zesheng; Niu, Junfeng; Rao, Neti Nageswara

    2015-10-01

    Electrochemical oxidation of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) over metal-oxide-coated Ti anodes, i.e., Ti/SnO2-Sb/Ce-PbO2, Ti/SnO2-Sb and Ti/RuO2, was examined. The degradation efficiency of over 90% was attained at 20min at different initial concentrations (0.5-20mgL(-1)) and initial pH values (3.1-11.2). The degradation efficiencies of 2,4,5-T on Ti/SnO2-Sb/Ce-PbO2, Ti/SnO2-Sb and Ti/RuO2 anodes were higher than 99.9%, 97.2% and 91.5% at 30min, respectively, and the respective total organic carbon removal ratios were 65.7%, 54.6% and 37.2%. The electrochemical degradation of 2,4,5-T in aqueous solution followed pseudo-first-order kinetics. The compounds, i.e., 2,5-dichlorohydroquinone and 2,5-dihydroxy-p-benzoquinone, have been identified as the main aromatic intermediates by liquid chromatography-mass spectrometry. The results showed that the energy efficiencies of 2,4,5-T (20mgL(-1)) degradation with Ti/SnO2-Sb/Ce-PbO2 anode at the optimal current densities from 2 to 16mAcm(-2) ranged from 8.21 to 18.73kWhm(-3). PMID:25981800

  2. Synthesis and characterization of a nanocomposite of goethite nanorods and reduced graphene oxide for electrochemical capacitors

    SciTech Connect

    Shou Qingliang [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Cheng Jipeng, E-mail: chengjp@zju.edu.cn [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Zhang Li, E-mail: lizhang@ethz.ch [Institute of Robotics and Intelligent Systems, ETH Zurich, CH-8092 Zurich (Switzerland); Nelson, Bradley J. [Institute of Robotics and Intelligent Systems, ETH Zurich, CH-8092 Zurich (Switzerland); Zhang Xiaobin [State Key Laboratory of Silicon Materials, Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China)

    2012-01-15

    We report a one-step synthesis of a nanocomposite of goethite ({alpha}-FeOOH) nanorods and reduced graphene oxide (RGO) using a solution method in which ferrous cations serve as a reducing agent of graphite oxide (GO) to graphene and a precursor to grow goethite nanorods. As-prepared goethite nanorods have an average length of 200 nm and a diameter of 30 nm and are densely attached on both sides of the RGO sheets. The electrochemical properties of the nanocomposite were characterized by cyclic voltammetry (CV) and chronopotentiometry (CP) charge-discharge tests. The results showed that goethite/RGO composites have a high electrochemical capacitance of 165.5 F g{sup -1} with an excellent recycling capability making the material promising for electrochemical capacitors. - Graphical abstract: The reduced graphene oxide sheets are decorated with goethite nanorods. The as-prepared composite exhibits a high electrochemical capacitance with good recycling capability, which is promising for supercapacitor applications. Higlights: Black-Right-Pointing-Pointer Ferrous ions act as reductant of graphite oxide and precursor of goethite nanorods. Black-Right-Pointing-Pointer Goethite nanorods are attached on both sides of the reduced graphene oxide sheets. Black-Right-Pointing-Pointer Composite exhibits a high specific capacitance and a good recycling capability. Black-Right-Pointing-Pointer Composite is promising for supercapacitor applications.

  3. Integrating electrochemical oxidation into forward osmosis process for removal of trace antibiotics in wastewater.

    PubMed

    Liu, Pengxiao; Zhang, Hanmin; Feng, Yujie; Shen, Chao; Yang, Fenglin

    2015-10-15

    During the rejection of trace pharmaceutical contaminants from wastewater by forward osmosis (FO), disposal of the FO concentrate was still an unsolved issue. In this study, by integrating the advantages of forward osmosis and electrochemical oxidation, a forward osmosis process with the function of electrochemical oxidation (FOwEO) was established for the first time to achieve the aim of rejection of trace antibiotics from wastewater and treatment of the concentrate at the same time. Results demonstrated that FOwEO (current density J=1mAcm(-2)) exhibited excellent rejections of antibiotics (>98%) regardless of different operation conditions, and above all, antibiotics in the concentrate were well degraded (>99%) at the end of experiment (after 3h). A synergetic effect between forward osmosis and electrochemical oxidation was observed in FOwEO, which lies in that antibiotic rejections by FO were enhanced due to the degradation of antibiotics in the concentrate, while the electrochemical oxidation capacity was improved in the FOwEO channel, of which good mass transfer and the assist of indirect oxidation owing to the reverse NaCl from draw solution were supposed to be the mechanism. This study demonstrated that the FOwEO has the capability to thoroughly remove trace antibiotics from wastewater. PMID:25966924

  4. Mediated electrochemical oxidation of organic wastes without electrode separators

    DOEpatents

    Farmer, Joseph C. (Newtown, PA); Wang, Francis T. (Danville, CA); Hickman, Robert G. (Livermore, CA); Lewis, Patricia R. (Livermore, CA)

    1996-01-01

    An electrochemical cell/electrolyte/mediator combination for the efficient destruction of organic contaminants using metal salt mediators in a sulfuric acid electrolyte, wherein the electrodes and mediator are chosen such that hydrogen gas is produced at the cathode and no cell membrane is required.

  5. Synthesis and electrochemical capacitance of long tungsten oxide nanorod arrays grown vertically on substrate

    SciTech Connect

    Park, Sun Hwa [Department of Nanomaterials Science and Engineering, University of Science and Technology, Daejeon 305-350 (Korea, Republic of)] [Department of Nanomaterials Science and Engineering, University of Science and Technology, Daejeon 305-350 (Korea, Republic of); Kim, Young Heon; Lee, Tae Geol; Shon, Hyun Kyong [Korea Research Institute of Standards and Science, Daejeon 305-340 (Korea, Republic of)] [Korea Research Institute of Standards and Science, Daejeon 305-340 (Korea, Republic of); Park, Hyun Min [Department of Nanomaterials Science and Engineering, University of Science and Technology, Daejeon 305-350 (Korea, Republic of) [Department of Nanomaterials Science and Engineering, University of Science and Technology, Daejeon 305-350 (Korea, Republic of); Korea Research Institute of Standards and Science, Daejeon 305-340 (Korea, Republic of); Song, Jae Yong, E-mail: jysong@kriss.re.kr [Korea Research Institute of Standards and Science, Daejeon 305-340 (Korea, Republic of); Department of Nano Science, University of Science and Technology, Daejeon 305-350 (Korea, Republic of)

    2012-11-15

    Highlights: ? Growth of long amorphous tungsten oxide nanorods on a substrate. ? Formation of single-crystalline tungsten oxide nanorods by a heat-treatment. ? High electrochemical pseudocapacitance of 2.8 mF cm{sup ?2}. ? Excellent cyclability of psuedocapacitance up to 1000 cycles. -- Abstract: Long tungsten oxide nanorods are vertically grown on Al/W/Ti coated silicon substrates using a two-step anodization process. The first anodization of the Al film forms a mesh-like mask of anodic aluminum oxide, and the second anodization of the W film results in the formation of a buffer layer, a bottom nanorod, and a top nanorod of amorphous tungsten oxide. A pore-widening process prior to the second anodization leads to the enhancement of nanorod length above approximately 500 nm. After a heat-treatment, the tungsten oxide nanorods are crystallized to form a single crystalline structure while the buffer layer forms a polycrystalline structure. The crystalline tungsten oxide nanorods show a cyclic voltammogram retaining the quasi-rectangular shape of an electrochemically reversible faradaic redox reaction, i.e., a typical pseudocapacitive behavior. The maximum electrochemical capacitance per apparent surface area reaches approximately 2.8 mF cm{sup ?2} at the voltage scan rate of 20 mV s{sup ?1}, and the excellent cyclability of charge–discharge process is maintained up to 1000 cycles.

  6. Novel insights into the electrochemical detection of nitric oxide in biological systems.

    PubMed

    Pekarová, M; Lojek, A; Hrbá?, J; Kuchta, R; Kadlec, J; Kubala, L

    2014-01-01

    In recent years, microsensor technologies have made a rapid expansion into different fields of physical sciences, engineering, and biomedicine. For analyses of various biomolecules, novel sensors and detection platforms in the electrochemical field have been reported recently. The most important applications based on microelectromechanical systems dramatically reduce the need of manipulation steps with samples, while improving data quality and quantitative capabilities. This is also the case of a special class of electrochemical sensors that allow direct, real-time and non-invasive measurements of nitric oxide, whose determination is crucial for the purposes of basic research, as well as of preclinical and clinical studies. Therefore, this minireview will focus on the description of recent discoveries in the electrochemical determination of nitric oxide, released in different in vitro systems. PMID:25369335

  7. Electrochemical inactivation of paper mill bacteria with mixed metal oxide electrode.

    PubMed

    Särkkä, Heikki; Vepsäläinen, Mikko; Pulliainen, Martti; Sillanpää, Mika

    2008-08-15

    In this study electrochemical inactivation of selected bacteria living in paper mill circulating waters was investigated. Three aerobic bacteria species (Deinococcus geothermalis, Pseudoxanthomonas taiwanensis and Meiothermus silvanus) were inactivated effectively (>2 log) at a mixed metal oxide (MMO) electrode in 3 min. The influence of parameters, such as current density and initial pH or chloride concentration of synthetic paper machine water (SPW) on the inactivation efficiency were studied. Increasing current density and initial chloride concentration of SPW increased the inactivation rate but change of pH value did not have significant influence on the inactivation rate. It was observed that inactivation was mainly due to the electrochemically generated chlorine/hypochlorite. Electrochemical oxidation showed good performance for inactivation these primary biofilm forming bacteria species with improved current efficiency by higher initial chloride concentrations. PMID:18206301

  8. Dependence of Electrochemical Properties of Vanadium Oxide Films on Their Nano-and Microstructures

    E-print Network

    Cao, Guozhong

    Dependence of Electrochemical Properties of Vanadium Oxide Films on Their Nano- and Microstructures Vanadium pentoxide (V2O5) has attracted a lot of attention as a Li intercalation host, due to its layered of nanostructured electrodes, however, mainly relies on the template-based growth methods. The advantages

  9. Physical, mechanical and electrochemical characterization of all-perovskite intermediate temperature solid oxide fuel cells

    Microsoft Academic Search

    Alidad Mohammadi

    2008-01-01

    Strontium- and magnesium-doped lanthanum gallate (LSGM) has been considered as a promising electrolyte for solid oxide fuel cell (SOFC) systems in recent years due to its high ionic conductivity and chemical stability over a wide range of oxygen partial pressures and temperatures. This research describes synthesis, physical and mechanical behavior, electrochemical properties, phase evolution, and microstructure of components of an

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

    PubMed

    Siriviriyanun, Ampornphan; Imae, Toyoko

    2013-04-14

    Electrochemical sensors consisting of electrodes loaded with carbon nanotubes and Pt nanoparticles (PtNPs) protected by dendrimers have been developed using a facile method to fabricate them on two types of disposable electrochemical printed chips with a screen-printed circular gold or a screen-printed circular glassy carbon working electrode. The electrochemical performance of these sensors in the oxidation of methanol was investigated by cyclic voltammetry. It was revealed that such sensors possess stable durability and high electrocatalytic activity: the potential and the current density of an anodic peak in the oxidation of methanol increased with increasing content of PtNPs on the electrodes, indicating the promotion of electrocatalytic activity in relation to the amount of catalyst. The low anodic potential suggests the easy electrochemical reaction, and the high catalyst tolerance supports the almost complete oxidation of methanol to carbon dioxide. The significant performance of these sensors in the detection of methanol oxidation comes from the high electrocatalytic ability of PtNPs, excellent energy transfer of carbon nanotubes and the remarkable ability of dendrimers to act as binders. Thus these systems are effective for a wide range of applications as chemical, biomedical, energy and environmental sensors and as units of direct methanol fuel cells. PMID:23435635

  11. Written-in conductive patterns on robust graphene oxide biopaper by electrochemical microstamping.

    PubMed

    Hu, Kesong; Tolentino, Lorenzo S; Kulkarni, Dhaval D; Ye, Chunhong; Kumar, Satish; Tsukruk, Vladimir V

    2013-12-16

    The silk road: By employing silk fibroin as a binder between graphene oxide films and aluminum foil for a facile, highly localized reduction process, conductive paper is reinvented. The flexible, robust biographene papers have high toughness and electrical conductivity. This electrochemical written-in approach is readily applicable for the fabrication of conductive patterned papers with complex circuitries. PMID:24214828

  12. Continuous treatment of textile wastewater by combined coagulation, electrochemical oxidation and activated sludge

    Microsoft Academic Search

    Sheng H. Lin; Chi F. Peng

    1996-01-01

    Treatment of text wastewaters from a large dyeing and finishing mill by a continuous process of combined chemical coagulation, electrochemical oxidation and activated sludge treatment is investigated. The experimental results are assessed in terms of COD and color (turbidity) reductions to determine the overall treatment efficiency of the combined process. Operating variables, such as the wastewater flow rate, conductivity, pH,

  13. 3D CFD ELECTROCHEMICAL AND HEAT TRANSFER MODEL OF AN INTERNALLY MANIFOLDED SOLID OXIDE ELECTROLYSIS CELL

    Microsoft Academic Search

    Grant L. Hawkes; James E. OBrien; Greg Tao

    2011-01-01

    A three-dimensional computational fluid dynamics (CFD) electrochemical model has been created to model high-temperature electrolysis cell performance and steam electrolysis in an internally manifolded planar solid oxide electrolysis cell (SOEC) stack. This design is being evaluated at the Idaho National Laboratory for hydrogen production from nuclear power and process heat. Mass, momentum, energy, and species conservation and transport are provided

  14. Electrochemical Urea Biosensor Based on Sol-gel Derived Nanostructured Cerium Oxide

    Microsoft Academic Search

    Anees A Ansari; B D Malhotra

    2012-01-01

    Urease (Urs) and glutamate dehydrogenase (GLDH) have been co-immobilized onto a nanostructured–cerium oxide (Nano-CeO2) film deposited onto a indium-tin-oxide (ITO) coated glass substrate by dip-coating via sol-gel process for urea detection. This nanostructured film has characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR), Scanning electron microscope (SEM) and electrochemical techniques, respectively. The particle size of the Nano-CeO2 film has

  15. Nitric oxide measurement in biological and pharmaceutical samples by an electrochemical sensor

    Microsoft Academic Search

    Fang Wang; Xiaocui Deng; Wei Wang; Zilin Chen

    2011-01-01

    A nitric oxide (NO) electrochemical sensor was developed via one-step construction of gold nanoparticles (GNPs)–chitosan (CS)\\u000a nanocomposite sensing film on a glassy carbon electrode (GCE) surface. This method is very simple and convenient. The GNPs–CS\\u000a film which is controllable and stable exhibits catalytic activity to NO oxidation. The anodic peak potential significantly\\u000a shifted negatively compared with that at bare GCE.

  16. Electrochemical oxidation processes on Ni electrodes in propylene carbonate containing various electrolyte salts

    Microsoft Academic Search

    Kiyoshi Kanamura; Shigetaka Toriyama; Soshi Shiraishi; Zenichiro Takehara

    1996-01-01

    Electrochemical oxidation processes on Ni electrodes in propylene carbonate electrolytes were investigated by using cyclic voltammetry, X-ray photoelectron spectroscopy, and in situ Fourier transform infrared spectroscopy. The results of these analyses suggest that Ni electrodes, electrolyte salts, and solvent are oxidized at a greater anodic potential than 4.2 V vs. Li\\/Li{sup +}. When propylene carbonate (PC) electrolyte containing LiAsFâ, LiBFâ,

  17. Electrochemical DNA biosensors based on thin gold films sputtered on capacitive nanoporous niobium oxide

    Microsoft Academic Search

    Sangchul Rho; Deokjin Jahng; Jae Hoon Lim; Jinsub Choi; Jeong Ho Chang; Sang Cheon Lee; Kyung Ja Kim

    2008-01-01

    Electrochemical DNA biosensors based on a thin gold film sputtered on anodic porous niobium oxide (Au@Nb2O5) are studied in detail here. We found that the novel DNA biosensor based on Au@Nb2O5 is superior to those based on the bulk gold electrode or niobium oxide electrode. For example, the novel method does not require any time-consuming cleaning step in order to

  18. Electrochemical and electrochromic properties of niobium oxide thin films fabricated by pulsed laser deposition

    Microsoft Academic Search

    Zheng-Wen Fu; J. J. Kong; Q. Z. Qin

    1999-01-01

    Niobium oxide thin films have been successfully fabricated on the indium-tin oxide coated glasses by pulsed laser deposition in an Oâ\\/Oâ gas mixture. Films are characterized by X-ray diffraction and Raman spectrometry. Electrochemical and electrochromic properties of NbâOâ films are examined by cyclic voltammogram and potential step coupled with an in situ charge-coupled device spectrophotometer. The unique characteristics of absorption

  19. Electrochemical oxidation of boron containing compounds on titanium carbide and its implications to direct fuel cells

    Microsoft Academic Search

    Vankayala Kiran; Suresh Babu Kalidindi; Balaji Rao Jagirdar; Srinivasan Sampath

    Electrochemical oxidation of sodium borohydride (NaBH4) and ammonia borane (NH3BH3) (AB) have been studied on titanium carbide electrode. The oxidation is followed by using cyclic voltammetry, chronoamperometry and polarization measurements. A fuel cell with TiC as anode and 40wt% Pt\\/C as cathode is constructed and the polarization behaviour is studied with NaBH4 as anodic fuel and hydrogen peroxide as catholyte.

  20. Electrochemical oxidation of phenol for wastewater treatment using SnO 2 , anodes

    Microsoft Academic Search

    Ch. Comninellis; C. Pulgarin

    1993-01-01

    The electrochemical oxidation of phenol for waste water treatment was studied on doped SnO2 anodes. Analysis of reaction intermediates and a carbon balance has shown that the main reaction is oxidation of phenol to CO2. This unexpected behaviour of the SnO2 anode is explained by a change of the chemical structure of the electrode surface during anodic polarization.

  1. Manganese oxide embedded polypyrrole nanocomposites for electrochemical supercapacitor

    Microsoft Academic Search

    R. K. Sharma; A. C. Rastogi; S. B. Desu

    2008-01-01

    MnO2 embedded PPy nanocomposite (MnO2\\/PPy) thin film electrodes were electrochemically synthesized over polished graphite susbtrates. Growing PPy polymer chains provides large surface area template that enables MnO2 to form as nanoparticles embeded within polymer matrix. Co-deposition of MnO2 and PPy has a complimentary action in which porous PPy matrix provides high active surface area for the MnO2 nanoparticles and, on

  2. Preparation, characterization, and electrochemical application of mesoporous copper oxide

    SciTech Connect

    Cheng, Liang [Functional Nano and Soft Materials Laboratory (FUNSOM), Soochow University, Suzhou 215123 (China) [Functional Nano and Soft Materials Laboratory (FUNSOM), Soochow University, Suzhou 215123 (China); Anhui Key Laboratory of Functional Molecular Solids, and College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000 (China); Shao, Mingwang, E-mail: mwshao@suda.edu.cn [Functional Nano and Soft Materials Laboratory (FUNSOM), Soochow University, Suzhou 215123 (China) [Functional Nano and Soft Materials Laboratory (FUNSOM), Soochow University, Suzhou 215123 (China); Anhui Key Laboratory of Functional Molecular Solids, and College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000 (China); Chen, Dayan; Zhang, Yuzhong [Anhui Key Laboratory of Functional Molecular Solids, and College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000 (China)] [Anhui Key Laboratory of Functional Molecular Solids, and College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000 (China)

    2010-02-15

    Mesoporous CuO was successfully synthesized via thermal decomposition of CuC{sub 2}O{sub 4} precursors. These products had ring-like morphology, which was made up of nanoparticles with the average diameter of 40 nm. The electrochemical experiments showed that the mesoporous CuO decreased the overvoltage of the electrode and increased electron transference in the measurement of dopamine.

  3. Induced effects of advanced oxidation processes

    PubMed Central

    Liu, Peng; Li, Chaolin; Zhao, Zhuanjun; Lu, Gang; Cui, Haibo; Zhang, Wenfang

    2014-01-01

    Hazardous organic wastes from industrial, military, and commercial activities represent one of the greatest challenges to human beings. Advanced oxidation processes (AOPs) are alternatives to the degradation of those organic wastes. However, the knowledge about the exact mechanisms of AOPs is still incomplete. Here we report a phenomenon in the AOPs: induced effects, which is a common property of combustion reaction. Through analysis EDTA oxidation processes by Fenton and UV-Fenton system, the results indicate that, just like combustion, AOPs are typical induction reactions. One most compelling example is that pre-feeding easily oxidizable organic matter can promote the oxidation of refractory organic compound when it was treated by AOPs. Connecting AOPs to combustion, it is possible to achieve some helpful enlightenment from combustion to analyze, predict and understand AOPs. In addition, we assume that maybe other oxidation reactions also have induced effects, such as corrosion, aging and passivation. Muchmore research is necessary to reveal the possibilities of induced effects in those fields. PMID:24503715

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

    DOEpatents

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

    2010-11-23

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

  5. Advances in electrochemical Fe(VI) synthesis and analysis

    Microsoft Academic Search

    Xingwen Yu; Stuart Licht

    2008-01-01

    Hexavalent iron species (Fe(VI)) have been known for over a century, and have long-time been investigated as the oxidant for\\u000a water purification, as the catalysts in organic synthesis and more recently as cathodic charge storage materials. Conventional\\u000a Fe(VI) syntheses include solution phase oxidation (by hyphchlorite) of Fe(III), and the synthesis of less soluble super-irons\\u000a by dissolution of FeO4\\u000a 2?, and

  6. Catalytic activity of NiMnO3 for visible light-driven and electrochemical water oxidation.

    PubMed

    Hong, Dachao; Yamada, Yusuke; Nomura, Akifumi; Fukuzumi, Shunichi

    2013-11-28

    NiMnO3 was found to be an efficient catalyst for light-driven water oxidation using [Ru(bpy)3](2+) and S2O8(2-) as a photosensitiser and a sacrificial oxidant, respectively. NiMnO3 exhibited remarkably high catalytic activity in comparison with manganese oxides and nickel oxide. For electrochemical water oxidation, the highest catalytic current was also obtained with NiMnO3 among the manganese oxides. PMID:24113542

  7. Novel SOFC anodes for the direct electrochemical oxidation of hydrocarbon

    Microsoft Academic Search

    R. J. Gorte; H. Kim; J. M. Vohs

    2002-01-01

    This paper describes recent developments in solid-oxide fuel cells (SOFC) that use Cu-based cermets as the anode for direct oxidation of hydrocarbon fuels, including liquids such as gasoline, to generate electrical power without the need for first reforming that fuel to H2. Cu–YSZ cermets were found to be stable in hydrocarbon environments, but exhibited low performance for direct oxidation. Reasonable

  8. Towards electrochemical purification of chemically reduced graphene oxide from redox accessible impurities.

    PubMed

    Tan, Shu Min; Ambrosi, Adriano; Khezri, Bahareh; Webster, Richard D; Pumera, Martin

    2014-04-21

    The electrochemical properties of graphene are highly sensitive to residual metallic impurities that persist despite various purification efforts. To accurately evaluate the electrochemical performance of graphene, highly purified materials free of metallic impurities are required. In this study, the partial purification of chemically reduced graphene oxides prepared via Hummers (CRGO-HU) and Staudenmaier (CRGO-ST) oxidation methods was performed through cyclic voltammetric (CV) scans executed in nitric acid, followed by CV measurements of cumene hydroperoxide (CHP). The purification of graphene was monitored by the changes in the peak current and potential of CHP which is sensitive to iron impurities. The CRGOs were characterised by inductively coupled plasma-mass spectrometry (ICP-MS), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and CV. The micrographs revealed CRGOs of similar morphologies, but with greater defects in CRGO-HU. The dependencies of CHP peak current and peak potential on the number of purification cycles exhibit greater efficiency of removing iron impurities from CRGO-HU than CRGO-ST. This can be attributed to the oxidative method that is used in CRGO-HU production, which exposes more defect sites for iron impurities to reside in. This facile electrochemical purification of graphenes can be utilised as a routine preparation and cleaning method of graphene before electrochemical measurements for analytes that show exceptional sensitivity towards electrocatalytic metallic impurities in sp(2) nanocarbon materials. PMID:24615543

  9. Polymer-directed synthesis of metal oxide-containing nanomaterials for electrochemical energy storage

    NASA Astrophysics Data System (ADS)

    Mai, Yiyong; Zhang, Fan; Feng, Xinliang

    2013-12-01

    Metal oxide-containing nanomaterials (MOCNMs) of controllable structures at the nano-scale have attracted considerable interest because of their great potential applications in electrochemical energy storage devices, such as lithium-ion batteries (LIBs) and supercapacitors. Among many structure-directing agents, polymers and macromolecules, including block copolymers (BCPs) and graphene, exhibit distinct advantages in the template-assisted synthesis of MOCNMs. In this feature article, we introduce the controlled preparation of MOCNMs employing BCPs and graphene as structure-directing agents. Typical synthetic strategies are presented for the control of structures and sizes as well as the improvement of physical properties and electrochemical performance of MOCNMs in LIBs and supercapacitors.

  10. Radio frequency sputtered cobalt oxide coating: Structural, optical, and electrochemical characterization

    NASA Astrophysics Data System (ADS)

    Estrada, W.; Fantini, M. C. A.; de Castro, S. C.; Polo da Fonseca, C. N.; Gorenstein, A.

    1993-11-01

    Cobalt oxide thin films (thickness 2000 Å) with different stoichiometries were deposited by reactive rf sputtering. The variation of the oxygen partial pressure lead to films with compositions varying from metallic cobalt to CO3O4, as determined by x-ray diffraction and x-ray photoelectron spectroscopy. The electrochromic properties of the films were investigated in aqueous electrolytes (0.1 M KOH). The initial electrochemical behavior of the films is strongly dependent on the film deposition conditions, but after cycling the electrochemical/electrochromic characteristics of the different deposits were quite similar. Transmittance changes and electrochromic efficiency are discussed.

  11. Thermo-electrochemical modeling of ammonia-fueled solid oxide fuel cells considering ammonia thermal decomposition in the anode

    Microsoft Academic Search

    Meng Ni

    2011-01-01

    Ammonia (NH3) is a promising hydrogen carrier and a possible fuel for use in Solid Oxide Fuel Cells (SOFCs). In this study, a 2D thermo-electrochemical model is developed to investigate the heat\\/mass transfer, chemical (ammonia thermal decomposition) and electrochemical reactions in a planar SOFC running on ammonia. The model integrates three sub-models: (1) an electrochemical model relating the current density–voltage

  12. Degradation of methylparathion in aqueous solution by electrochemical oxidation.

    PubMed

    Vlyssides, Apostolos; Barampouti, Elli Maria; Mai, Sofia; Arapoglou, Dimitris; Kotronarou, Anastasia

    2004-11-15

    The electrochemical degradation of methylparathion has been investigated by using Ti/Pt as anode, Stainless Steel 304 as cathode, and sodium chloride as electrolyte. The pesticide is rapidly degraded, but full mineralization is not observed. Degradation products have been monitored through gas chromatography and mass spectrometry, and the overall degradation process has been monitored through dissolved and particulate organic carbon, sulfur, and phosphorus measurements. Several intermediates have been identified, and oxalic, formic, and acetic acids as well as tetraphosphorus trisulfide have been recognized as final products of the degradation process. A proposed mechanism of the process is presented. PMID:15573616

  13. Advanced Electrochemical Technologies for Hydrogen Production by Alternative Thermochemical Cycles

    SciTech Connect

    The Pennsylvania State Univeristy: Serguei Lvov, Mike Chung, Mark Fedkin, Victor Balashov, Elena, Chalkova, Nikolay Akinfiev; University of South Carolina: Carol Stork, Thomas Davis, Francis Gadala-Maria, Thomas Stanford, John Weidner; Tulane University: Victor Law, John Prindle; Lewis, ANL: Michele

    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 oC 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 reactions going to completion without side reactions, and lower demands on materials of construction. Three university research groups from PSU, USC, and TU as well as a group from ANL have been collaborating on the development of enabling technologies for the Cu-Cl cycle, including experimental work on the Cu-Cl cycle reactions, modeling and simulation, and particularly electrochemical reaction for hydrogen production using a CuCl electrolyzer. The Consortium research was distributed over the participants and organized in the following tasks: (1) Development of CuCl electrolyzer (PSU), (2) Thermodynamic modeling of anolyte solution (PSU), (3) Proton conductive membranes for CuCl electrolysis (PSU), (4) Development of an analytical method for online analysis of copper compounds in highly concentrated aqueous solutions (USC), (5) Electrodialysis as a means for separation and purification of the streams exiting the electrolyzer in the Cu-Cl cycle (USC), (6) Development of nanostructured electrocatalysts for the Cu-Cl electrolysis (USC), (7) Cu-Cl electrolyzer modeling (USC), (8) Aspen Plus modeling of the Cu-Cl thermochemical cycle (TU), (9) International coordination of research on the development of the Cu-Cl thermochemical cycle (ANL). The results obtained in the project clearly demonstrate that the Cu-Cl alternative thermochemical cycle is a promising and viable technology to produce hydrogen efficiently.

  14. Removal of Chloride from Wastewater by Advanced Softening Process Using Electrochemically Generated Aluminum Hydroxide 

    E-print Network

    Mustafa, Syed Faisal

    2014-07-23

    REMOVAL OF CHLORIDE FROM WASTEWATER BY ADVANCED SOFTENING PROCESS USING ELECTROCHEMICALLY GENERATED ALUMINUM HYDROXIDE A Thesis by SYED FAISAL MUSTAFA Submitted to the Office of Graduate and Professional Studies of Texas A&M... University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Chair of Committee, Ahmed Abdel-Wahab Committee Members, Mohamed Nounou Mahmood Amani Head of Department, M. Nazmul Karim August 2014 Major...

  15. Performance Evaluation of SOFC System usingElectrochemical Direct Oxidation of Methane

    NASA Astrophysics Data System (ADS)

    Yokoo, Masayuki; Take, Tetsuo; Ohtsu, Satoshi

    We evaluated the performance of systems composed of a solid oxide fuel cell (SOFC) using electrochemical direct oxidation of methane and a conventional steam-reforming-type SOFC (SRSOFC). Net thermal efficiency in an atmospheric partial-oxidation-type SOFC (POSOFC)-SRSOFC system was 8% higher than that in a simple SRSOFC system in the output range of more than 35 kW. The efficiency in a pressurized POSOFC-SRSOFC-gas-turbine (GT) system was slightly higher than that in a pressurized SRSOFC-GT system.

  16. Electrochemical corrosion and oxidation resistances of Zr60Ni21Al19 bulk amorphous alloys

    NASA Astrophysics Data System (ADS)

    Jing, Qin; Zhang, Bing; Zhang, Jin; Ma, Mingzhen; Liu, Riping

    2010-12-01

    Electrochemical corrosion and oxidation resistances of Zr60Ni21Al19 amorphous alloy were studied. The ternary amorphous alloy exhibits greater positive potential than its crystalline counterpart and 0Cr19Ni9Ti stainless steel. Its weight loss result measured in 2 mol/L HCl solution is in agreement with the potentiodynamic curve. But there is no obvious difference in the oxidation resistances between Zr60Ni21Al19 amorphous and its crystalline alloys. They both exhibit high oxidation resistance.

  17. Vanadium oxide nanodisks: Synthesis, characterization, and electrochemical properties

    SciTech Connect

    Ren, Ling [Key Laboratory of Cluster Science, Ministry of Education of China, Department of Chemistry, Beijing Institute of Technology, Beijing 100081 (China)] [Key Laboratory of Cluster Science, Ministry of Education of China, Department of Chemistry, Beijing Institute of Technology, Beijing 100081 (China); Cao, Minhua, E-mail: caomh@bit.edu.cn [Key Laboratory of Cluster Science, Ministry of Education of China, Department of Chemistry, Beijing Institute of Technology, Beijing 100081 (China)] [Key Laboratory of Cluster Science, Ministry of Education of China, Department of Chemistry, Beijing Institute of Technology, Beijing 100081 (China); Shi, Shufeng [Department of Chemistry, Northeast Normal University, Changchun 13324 (China)] [Department of Chemistry, Northeast Normal University, Changchun 13324 (China); Hu, Changwen [Key Laboratory of Cluster Science, Ministry of Education of China, Department of Chemistry, Beijing Institute of Technology, Beijing 100081 (China)] [Key Laboratory of Cluster Science, Ministry of Education of China, Department of Chemistry, Beijing Institute of Technology, Beijing 100081 (China)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer Highly crystallined VO{sub 1.6}{center_dot}H{sub 2}O nanodisks have been synthesized by using a novel solid-solution-solid growth process. Black-Right-Pointing-Pointer The nanodisks are assembled from nanoparticles. Black-Right-Pointing-Pointer PEG-4000 plays an important role for the formation of the nanodisks. Black-Right-Pointing-Pointer The as-synthesized nanodisks exhibit good electrochemical behavior. -- Abstract: Highly crystallined VO{sub 1.6}{center_dot}H{sub 2}O nanodisks assembled from nanoparticles have been successfully fabricated under hydrothermal conditions by using bulk V{sub 2}O{sub 5} and Na{sub 2}S{sub 2}O{sub 3} as the starting materials in the presence of surfactant polyethylene glycol 4000 (PEG-4000). The nanodisks have a diameter of 200 nm and thickness of 40 nm. Hollow nanodisks are occasionally observed, which is similar to Chinese ancient copper coins. The formation of nanodisks can be ascribed to a novel solid-solution-solid growth mechanism. Compared with other methods, the solid state transformation method is simple and economic. In addition, the nanodisks exhibit good electrochemical behavior and promising to be used in lithium-ion battery.

  18. Boosting supercapacitor performance of carbon fibres using electrochemically reduced graphene oxide additives.

    PubMed

    Cao, Yachang; Zhu, Miao; Li, Peixu; Zhang, Rujing; Li, Xinming; Gong, Qianming; Wang, Kunling; Zhong, Minlin; Wu, Dehai; Lin, Feng; Zhu, Hongwei

    2013-12-01

    Modifying conventional materials with new recipes represents a straightforward yet efficient way to realize large-scale applications of new materials. Electrochemically reduced graphene oxide (ERGO) coated carbon fibres (CFs), prepared as fibre-like supercapacitor electrodes, exhibited excellent electrochemical energy storage performance. Upon addition of only a small amount (~1 wt%) of ERGO, the hybrid fibres showed superior electrochemical capacitances (nearly three orders of magnitude enhanced) compared to pure CFs in both aqueous and gel electrolytes. Meanwhile, the energy density did not decrease notably as the power density increased. The superior capacitive performance could be attributed to the synergistic effect between wrinkled and porous ERGO sheets and highly conductive CFs. This fibre electrode material also offered advantages such as easy operation, mass production capability, mechanical flexibility and robustness, and could have an impact on a wide variety of potential applications in energy and electronic fields. PMID:24141749

  19. Enhancing electrochemical detection on graphene oxide-CNT nanostructured electrodes using magneto-nanobioprobes

    PubMed Central

    Sharma, Priyanka; Bhalla, Vijayender; Dravid, Vinayak; Shekhawat, Gajendera; Jinsong-Wu, J W; Prasad, E. Senthil; Suri, C. Raman

    2012-01-01

    Graphene and related materials have come to the forefront of research in electrochemical sensors during recent years due to the promising properties of these nanomaterials. Further applications of these nanomaterials have been hampered by insufficient sensitivity offered by these nanohybrids for the type of molecules requiring lower detection ranges. Here, we report a signal amplification strategy based on magneto-electrochemical immunoassay which combines the advantages of carbon nanotube and reduced graphene oxide together with electrochemical bursting of magnetic nanoparticles into a large number of metal ions. Sensitive detection was achieved by precisely designing the nanohybrid and correlating the available metal ions with analyte concentration. We confirmed the ultrahigh sensitivity of this method for a new generation herbicide diuron and its analogues up to sub-picomolar concentration in standard water samples. The novel immune-detection platform showed the excellent potential applicability in rapid and sensitive screening of environmental pollutants or toxins in samples. PMID:23166860

  20. Modified cermet fuel electrodes for solid oxide electrochemical cells

    DOEpatents

    Ruka, Roswell J. (Churchill Boro, PA); Spengler, Charles J. (Murrysville, PA)

    1991-01-01

    An exterior porous electrode (10), bonded to a solid oxygen ion conducting electrolyte (13) which is in contact with an interior electrode (14), contains coarse metal particles (12) of nickel and/or cobalt, having diameters from 3 micrometers to 35 micrometers, where the coarse particles are coated with a separate, porous, multiphase layer (17) containing fine metal particles of nickel and/or cobalt (18), having diameters from 0.05 micrometers to 1.75 micrometers and conductive oxide (19) selected from cerium oxide, doped cerium oxide, strontium titanate, doped strontium titanate and mixtures thereof.

  1. Graphene electrode modified with electrochemically reduced graphene oxide for label-free DNA detection.

    PubMed

    Li, Bing; Pan, Genhua; Avent, Neil D; Lowry, Roy B; Madgett, Tracey E; Waines, Paul L

    2015-10-15

    A novel printed graphene electrode modified with electrochemically reduced graphene oxide was developed for the detection of a specific oligonucleotide sequence. The graphene oxide was immobilized onto the surface of a graphene electrode via ?-? bonds and electrochemical reduction of graphene oxide was achieved by cyclic voltammetry. A much higher redox current was observed from the reduced graphene oxide-graphene double-layer electrode, a 42% and 36.7% increase, respectively, in comparison with that of a bare printed graphene or reduced graphene oxide electrode. The good electron transfer activity is attributed to a combination of the large number of electroactive sites in reduced graphene oxide and the high conductivity nature of graphene. The probe ssDNA was further immobilized onto the surface of the reduced graphene oxide-graphene double-layer electrode via ?-? bonds and then hybridized with its target cDNA. The change of peak current due to the hybridized dsDNA could be used for quantitative sensing of DNA concentration. It has been demonstrated that a linear range from 10(-7)M to 10(-12)M is achievable for the detection of human immunodeficiency virus 1 gene with a detection limit of 1.58×10(-13)M as determined by three times standard deviation of zero DNA concentration. PMID:26002015

  2. Microfluidic Electrochemical Sensor for On-line Monitoring of Aerosol Oxidative Activity

    PubMed Central

    Sameenoi, Yupaporn; Koehler, Kirsten; Shapiro, Jeff; Boonsong, Kanokporn; Sun, Yele; Collett, Jeffrey; Volckens, John; Henry, Charles S.

    2012-01-01

    Particulate matter (PM) air pollution has a significant impact on human morbidity and mortality; however, the mechanisms of PM-induced toxicity are poorly defined. A leading hypothesis states that airborne PM induces harm by generating reactive oxygen species (ROS) in and around human tissues, leading to oxidative stress. We report here, a system employing a microfluidic electrochemical sensor coupled directly to a Particle-into-Liquid-Sampler (PILS) system to measure aerosol oxidative activity in an on-line format. The oxidative activity measurement is based on the dithiothreitol assay (DTT assay) where after oxidized by PM, the remaining reduced DTT was analyzed by the microfluidic sensor. The sensor consists of an array of working, reference, and auxiliary electrodes fabricated in a poly(dimethylsiloxane) (PDMS)-based microfluidic device. Cobalt (II) phthalocyanine (CoPC)-modified carbon paste was used as the working electrode material allowing selective detection of reduced DTT. The electrochemical sensor was validated off-line against the traditional DTT assay using filter samples taken from urban environments and biomass burning events. After off-line characterization, the sensor was coupled to a PILS to enable on-line sampling/analysis of aerosol oxidative activity. Urban dust and industrial incinerator ash samples were aerosolized in an aerosol chamber and analyzed for their oxidative activity. The on-line sensor reported DTT consumption rates (oxidative activity) in good correlation with aerosol concentration (R2 from 0.86–.97) with a time-resolution of approximately 3 minutes. PMID:22651886

  3. Commercial applications of electron beam advanced oxidation technology

    NASA Astrophysics Data System (ADS)

    Curry, Randy D.; Bosma, John T.

    1995-03-01

    Emerging commercial applications of electron-beam advanced oxidation technology offer a significant advancement in the treatment of waste steams. Both electron beam and X-ray (Brehmsstrahlung) advanced oxidation processes have been shown to be effective in the destruction of volatile and semivolatile organic compounds. Emerging commercial applications, however, far exceed in scope current applications of oxidation technologies for the destruction of simple semivolatile and volatile organic compounds in water. Emerging applications include direct treatment of contaminated soil, removal of metal ions from water and sterilization of water, sludges, and food. Application of electron beam advanced oxidation technologies are reviewed, along with electron- beam-generated X-ray (Brehmsstrahlung) advanced oxidation processes. Advantages of each technology are discussed along with advanced accelerator technologies which are applicable for commercial processing of waste streams. An overview of the U.S. companies and laboratories participating in this research area are included in this discussion.

  4. Treatment of papermaking tobacco sheet wastewater by electrocoagulation combined with electrochemical oxidation.

    PubMed

    Ma, Xiangjuan; Gao, Yang; Huang, Hanping

    2015-01-01

    Attempts were made in this study to examine the efficiency of electrocoagulation (EC) using aluminum (Al) anode and stainless steel net cathode combined with electrochemical oxidation with a ?-PbO2 anode or a mixed metal oxide (MMO) anode for treatment of papermaking tobacco sheet wastewater, which has the characteristics of high content of suspended solids (SS), intensive color, and low biodegradability. The wastewater was first subjected to the EC process under 40 mA/cm(2) of current density, 2.5 g/L of NaCl, and maintaining the original pH of wastewater. After 6 minutes of EC process, the effluent was further treated by electrochemical oxidation. The results revealed that the removal of SS during the EC process was very beneficial to mass transfer of organics during electrochemical oxidation. After the combined process, 83.9% and 82.8% of chemical oxygen demand (COD) removal could be achieved on the ?-PbO2 and MMO anodes, respectively. The main components of the final effluent were biodegradable organic acids, such as acetic acid, propionic acid, butyric acid, valeric acid, and hexahyl carbonic acid; the 5-day biochemical oxygen demand/chemical oxygen demand (BOD5/COD) ratio increased from 0.06 to 0.85 (Al + ?-PbO2) or 0.80 (Al + MMO). Therefore, this integrated process is a promising alternative for pretreatment of papermaking tobacco sheet wastewater prior to biological treatment. PMID:25909726

  5. Treatment of methyl orange dye wastewater by cooperative electrochemical oxidation in anodic-cathodic compartment.

    PubMed

    Pang, L; Wang, H; Bian, Z Y

    2013-01-01

    Electrochemical oxidation of methyl orange wastewater was studied using Ti/IrO(2)/RuO(2) anode and a self-made Pd/C O(2)-fed cathode in the divided cell with a terylene diaphragm. The result indicated that the appropriate rate of feeding air improved the methyl orange removal efficiency. The discoloration efficiency of methyl orange in the divided cell increased with increasing current density. The initial pH value had some effect on the discoloration of methyl orange, which became not obvious when the pH ranged from 2 to 10. However, the average removal efficiency of methyl orange wastewater in terms of total organic carbon (TOC) can reach 89.3%. The methyl orange structure had changed in the electrolytic process, and the characteristic absorption peak of methyl orange was about 470 nm. With the extension of electrolysis time, the concentration of methyl orange gradually reduced; wastewater discoloration rate increased gradually. The degradation of methyl orange was assumed to be cooperative oxidation by direct or indirect electrochemical oxidation at the anode and H(2)O(2), ·OH, O(2)(-)· produced by oxygen reduction at the cathode in the divided cell. Therefore, the cooperative electrochemical oxidation of methyl orange wastewater in the anodic-cathodic compartment had better degradation effects. PMID:23202555

  6. On-chip multi-electrochemical sensor array platform for simultaneous screening of nitric oxide and peroxynitrite

    E-print Network

    Paris-Sud XI, Université de

    On-chip multi-electrochemical sensor array platform for simultaneous screening of nitric oxide amperometric detection of nitric oxide (NO) and peroxynitrite (ONOOÀ ), two biologically relevant molecules those species, the balance between nitric oxide (NO), superoxide (O2 À ) and their reaction product

  7. Electrochemical fabrication of platinum nanoflakes on fulleropyrrolidine nanosheets and their enhanced electrocatalytic activity and stability for methanol oxidation reaction

    NASA Astrophysics Data System (ADS)

    Zhang, Xuan; Ma, Li-Xia

    2015-07-01

    Pyridine-functionalized fulleropyrrolidine nanosheets are prepared by a fast reprecipitation method under ultrasonication, and used as a novel nanostructured support materials to fabricate Pt catalyst nanoflakes by a simple electrodeposition approach. The as-prepared novel Pt-fullerene hybrid catalyst (Pt/PyC60) exhibits much enhanced electrocatalytic activity and stability for methanol oxidation reaction compared to the unsupported Pt nanoflakes and commercial Pt/C. The introduction of nanostructured fulleropyrrolidine as new support materials not only increases the electrochemically active surface area of catalyst, but also significantly improves the long-term stability. This will contribute to developing functionalized fullerenes as new nanostructured support materials for advanced electrocatalysts in fuel cells.

  8. An Investigation into the Effect of a Post-electroplating Electrochemical Oxidation Treatment on Tin Whisker Formation

    NASA Astrophysics Data System (ADS)

    Ashworth, M. A.; Haspel, D.; Wu, L.; Wilcox, G. D.; Mortimer, R. J.

    2015-01-01

    Since the `cracked oxide theory' was proposed by Tu in 1994,1 there has only been a limited number of studies that have sought to investigate the effect of the Sn oxide on whisker growth. The current study has used electrochemical oxidation to produce oxide films, which has enabled the effect of the surface oxide thickness on whisker growth to be established. The effect of oxide thickness on whisker growth has been investigated for tin electrodeposits on both Cu and brass substrates. The influence of applied oxidation potential on the thickness of the Sn oxide film has been investigated using x-ray photoelectron spectroscopy (XPS) for potassium bicarbonate-carbonate and borate buffer electrolyte solutions. Whisker growth from electrochemically oxidised Sn-Cu deposits on Cu and Sn deposits on brass has been investigated and compared with samples left to develop a native air-formed oxide. XPS studies show that the thickness of the electrochemically formed Sn oxide film is dependent on the applied oxidation potential and the total charge passed. Subsequent whisker growth studies demonstrate that electrochemically oxidised Sn-Cu deposits on Cu and Sn deposits on brass are significantly less susceptible to whisker growth than those having a native oxide film. For Sn deposits on brass, the electrochemically formed Sn oxide greatly reduces Zn oxide formation at the surface of the tin deposit, which results in whisker mitigation. For Sn-Cu deposits on Cu, the reduction in whisker growth must simply derive from the increased thickness of the Sn oxide, i.e. the Sn oxide film has an important role in stemming the development of whiskers.

  9. Electrochemical impedance spectroscopy studies of lithium diffusion in doped manganese oxide

    SciTech Connect

    Johnson, B.J.; Doughty, D.H.; Voigt, J.A.; Boyle, T.J.

    1996-06-01

    Cathode performance is critical to lithium ion rechargeable battery performance; effects of doping lithium manganese oxide cathode materials on cathode performance are being investigated. In this paper, Li diffusion in Al-doped LiMn{sub 2}O{sub 4} was studied and found to be controlled by the quantity of Al dopant. Electrochemical cycling was conducted at 0.5mA/cm{sub 2}; electrochemical impedance spectra were taken at open circuit potential, with impedance being measured at 65 kHz-0.01 Hz. As the Al dopant level was increased, the Li diffusion rate decreased; this was attributed to the decreased lattice parameter of the doped oxide.

  10. Strongly improved electrochemical cycling durability by adding iridium to electrochromic nickel oxide films.

    PubMed

    Wen, Rui-Tao; Niklasson, Gunnar A; Granqvist, Claes G

    2015-05-13

    Anodically colored nickel oxide (NiO) thin films are of much interest as counter electrodes in tungsten oxide based electrochromic devices such as "smart windows" for energy-efficient buildings. However, NiO films are prone to suffering severe charge density degradation upon prolonged electrochemical cycling, which can lead to insufficient device lifetime. Therefore, a means to improve the durability of NiO-based films is an important challenge at present. Here we report that the incorporation of a modest amount of iridium into NiO films [Ir/(Ir + Ni) = 7.6 atom %] leads to remarkable durability, exceeding 10000 cycles in a lithium-conducting electrolyte, along with significantly improved optical modulation during extended cycling. Structure characterization showed that the face-centered-cubic-type NiO structure remained after iridium addition. Moreover, the crystallinity of these films was enhanced upon electrochemical cycling. PMID:25919917

  11. A Molecularly Imprinted Polymer with Incorporated Graphene Oxide for Electrochemical Determination of Quercetin

    PubMed Central

    Sun, Si; Zhang, Mengqi; Li, Yijun; He, Xiwen

    2013-01-01

    The molecularly imprinted polymer based on polypyrrole film with incorporated graphene oxide was fabricated and used for electrochemical determination of quercetin. The electrochemical behavior of quercetin on the modified electrode was studied in detail using differential pulse voltammetry. The oxidation peak current of quercetin in B-R buffer solution (pH = 3.5) at the modified electrode was regressed with the concentration in the range from 6.0 × 10?7 to 1.5 × 10?5 mol/L (r2 = 0.997) with a detection limit of 4.8 × 10?8 mol/L (S/N = 3). This electrode showed good stability and reproducibility. In the above mentioned range, rutin or morin which has similar structures and at the same concentration as quercetin did not interfere with the determination of quercetin. The applicability of the method for complex matrix analysis was also evaluated. PMID:23698263

  12. Nano-Ag-Nafion modified Pt electrode for oxidation of volatile organic compounds: an electrochemical study.

    PubMed

    Muthuraman, G; Chung, Sang Joon; Moon, Il Shik

    2011-08-01

    In this work, we describe Nano-Ag-Nafion coated pt electrode for oxidation of volatile organic compound (VOC), here acetaldehyde. Electrochemically synthesized Nano-Ag-Nafion film on Pt was analyzed by electrochemically in various electrolyte solutions like nitric acid, sulfuric acid, potassium nitrate, and potassium hydroxide for its stability. High stability of Nano-Ag-Nafion film appeared in potassium hydroxide medium among electrolyte solutions studied. Electrocatalysis of acetaldehyde was occurred only in acid and neutral medium. A catalytic oxidative peak during cathodic voltammetric reduction scan was observed at 1.75 V, which, unusual redox behavior, follows EC' reaction path way between electrogenerated Ag(II) and acetaldehyde. For Nano-Ag potential applicability, a calibration plot was drawn from various concentration range of acetaldehyde to check the maximum concentration level of acetaldehyde degradation in air. PMID:22103205

  13. Advanced fabrication process for combined atomic force-scanning electrochemical microscopy (AFM-SECM) probes.

    PubMed

    Eifert, Alexander; Mizaikoff, Boris; Kranz, Christine

    2015-01-01

    An advanced software-controlled focused ion beam (FIB) patterning process for the fabrication of combined atomic force-scanning electrochemical microscopy (AFM-SECM) probes is reported. FIB milling is a standard process in scanning probe microscopy (SPM) for specialized SPM probe fabrication. For AFM-SECM, milling of bifunctional probes usually requires several milling steps. Milling such complex multi-layer/multi-material structures using a single milling routine leads to significantly reduced fabrication times and costs. Based on an advanced patterning routine, a semi-automated FIB milling routine for fabricating combined AFM-SECM probes with high reproducibility is presented with future potential for processing at a wafer level. The fabricated bifunctional probes were electrochemically characterized using cyclic voltammetry, and their performance for AFM-SECM imaging experiments was tested. Different insulation materials (Parylene-C and SixNy) have been evaluated with respect to facilitating the overall milling process, the influence on the electrochemical behavior and the long-term stability of the obtained probes. Furthermore, the influence of material composition and layer sequence to the overall shape and properties of the combined probes were evaluated. PMID:25259683

  14. Synthesis and electrochemical properties of lithium iron oxides with layer-related structures

    Microsoft Academic Search

    Ryoji Kanno; Takayuki Shirane; Yukishige Inaba; Yoji Kawamoto

    1997-01-01

    Two modifications of layered lithium iron oxides were synthesized and characterized by X-ray diffractometry and electrochemical measurements. LiFeO2 with ?-NaFeO2 structure was synthesized by the ion-exchange reaction in molten salts; cationic distribution in the host, ?-NaFeO2, affects the disordering in the reaction product. However, lithium de-intercalation was not confirmed. The ion-exchange reaction in molten salts gave a whole range of

  15. Electrochemical oxidation of bisphenol-A from aqueous solution using graphite electrodes

    Microsoft Academic Search

    M. Govindaraj; R. Rathinam; C. Sukumar; M. Uthayasankar; S. Pattabhi

    2012-01-01

    Electrochemical oxidation of bisphenol-A (BPA) from aqueous solution using graphite electrodes has been investigated. The effect of the types and concentration of supporting electrolytes, initial pH and applied current density on the performance of the process were examined. During electrolysis, concentration of BPA has been monitored and determined using UV-vis spectra, chemical oxygen demand (COD) and energy consumption. NaCl has

  16. Electrochemical testing of suspension plasma sprayed solid oxide fuel cell electrolytes

    Microsoft Academic Search

    D. Waldbillig; O. Kesler

    2011-01-01

    Electrochemical performance of metal-supported plasma sprayed (PS) solid oxide fuel cells (SOFCs) was tested for three nominal electrolyte thicknesses and three electrolyte fabrication conditions to determine the effects of electrolyte thickness and microstructure on open circuit voltage (OCV) and series resistance (Rs). The measured OCV values were approximately 90% of the Nernst voltages, and electrolyte area specific resistances below 0.1?cm2

  17. Electrochemical synthesis and sintering of nanocrystalline cerium(IV) oxide powders

    Microsoft Academic Search

    Z. Zhou; Richard J. Phillips; Jay A. Switzer

    1995-01-01

    Nanocrystalline CeOâ powders were prepared electrochemically by the cathodic electrogeneration of base, and their sintering behavior was investigated. X-ray diffraction and transmission electron microscopy revealed that the as-prepared powders were crystalline cerium(IV) oxide with the cubic fluorite structure. The lattice parameter of the electrogenerated material was 0.5419 nm. The powders consisted of nonaggregated, faceted particles. The average crystallite size was

  18. Mediated electrochemical oxidation of organic wastes using a Co(III) mediator in a neutral electrolyte

    DOEpatents

    Balazs, G.B.; Lewis, P.R.

    1999-07-06

    An electrochemical cell with a Co(III) mediator and neutral pH anolyte provides efficient destruction of organic and mixed wastes. The organic waste is concentrated in the anolyte reservoir, where the cobalt mediator oxidizes the organics and insoluble radioactive species and is regenerated at the anode until all organics are converted to carbon dioxide and destroyed. The neutral electrolyte is non-corrosive, and thus extends the lifetime of the cell and its components. 2 figs.

  19. Electrochemically initiated oxidative amination of benzoxazoles using tetraalkylammonium halides as redox catalysts.

    PubMed

    Gao, Wei-Jing; Li, Wei-Cui; Zeng, Cheng-Chu; Tian, Hong-Yu; Hu, Li-Ming; Little, R Daniel

    2014-10-17

    An electrochemically promoted coupling of benzoxazoles and amines has been developed, leading directly to the formation of 2-aminobenzoxazoles. The chemistry utilizes catalytic quantities of a tetraalkylammonium halide redox catalyst and is carried out under constant current conditions in a simple undivided cell. The use of excess chemical oxidant or large amounts of supporting electrolyte is avoided. This greatly simplifies the workup and isolation process and leads to a reduction in waste. PMID:25255384

  20. Electrochemical behavior of graphite highly fluorinated by high oxidation state complex fluorides and elemental fluorine

    Microsoft Academic Search

    T Nakajima; M Koh; V Gupta; B Žemva; K Lutar

    2000-01-01

    Highly fluorinated graphites have been synthesized by using elemental fluorine under pressure and high oxidation state complex fluoride, K2NiF6 or KAgF4 in anhydrous hydrogen fluoride. Their electrochemical discharge as a cathode of primary lithium battery has been investigated in organic electrolyte solution. Main products were stage 1 compounds or the stage 1 involving stage 2 and 3 phases as minor

  1. Mechanism of electrochemical oxidation of 1-chloro-2,2,6,6-tetramethylpiperidine

    Microsoft Academic Search

    E. Sh. Kagan; V. V. Yanilkin; V. I. Morozov; N. V. Nastapova; I. Yu. Zhukova; I. I. Kashparov; V. P. Kashparova

    2009-01-01

    In contrast to 2,2,6,6-tetramethylpiperidine and other aliphatic amines, at the electrochemical oxidation of 1-chloro-2,2,6,6-tetramethylpiperidine\\u000a a sufficiently stable cation-radical is formed. Its formation is confirmed by the data of cyclic voltammetry and electron\\u000a paramagnetic resonance. Further transformation of the cation-radical leads to the formation of 2,2,6,6-tetramethylpiperidin-1-oxyl.

  2. Electrochemical modeling of ammonia-fed solid oxide fuel cells based on proton conducting electrolyte

    Microsoft Academic Search

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

    2008-01-01

    An electrochemical model was developed to study the NH3-fed and H2-fed solid oxide fuel cells based on proton conducting electrolyte (SOFC-H). The modeling results were consistent with experimental data in literature. It is found that there is little difference in working voltage and power density between the NH3-fed and the H2-fed SOFC-H with an electrolyte-support configuration due to an extremely

  3. Electrochemical and electrochromic behavior of reactively sputtered nickel oxide

    Microsoft Academic Search

    Eric L. Miller; R. E. Rocheleau

    1997-01-01

    Nickel oxide thin films were deposited by reactive sputtering in a 20% oxygen\\/argon atmosphere for use as oxygen evolution catalysts in the photoelectrochemical production of hydrogen. The optical properties of the films were also characterized to evaluate their application as window layers. The polycrystalline films deposited at residual gas pressures of 6 or 10 mTorr exhibited moderate activity for oxygen

  4. Iridium and ruthenium complexes covalently bonded to carbon surfaces by means of electrochemical oxidation of aromatic amines

    Microsoft Academic Search

    Martina Sandroni; Giorgio Volpi; Jan Fiedler; Roberto Buscaino; Guido Viscardi; Luciano Milone; Roberto Gobetto; Carlo Nervi

    2010-01-01

    Bis(2-phenylpyridinate-C2,N)-(4-(4-aminophenyl)-2,2?-bipyridine) iridium(III) hexafluorophosphate and bis(2,2?-bipyridine-N,N?)-(4-(4-aminophenyl)-2,2?-bipyridine) ruthenium(II) hexafluorophosphate were synthesized and characterized. In particular, electrochemical analyses showed irreversible amine-centred oxidations, which were exploited to functionalize a glassy carbon electrode. The functionalization was achieved by electrochemical oxidation of the amino group.Surface modification was observed and studied via electrochemical techniques (cyclic voltammetry, square wave voltammetry).The functionalization was performed at different potential values, and

  5. Electrochemically regenerable carbon dioxide/moisture control technology for an Advanced Extravehicular Mobility Unit

    NASA Technical Reports Server (NTRS)

    Lee, M. C.; Sudar, M.; Cusick, R. J.

    1987-01-01

    Regenerable CO2/moisture removal techniques that reduce the expendables and logistics requirements are needed to sustain people undertaking EVAs for the Space Station. Here, the development of electrochemically regenerable CO2 absorption (ERCA) technology to replace the nonregenerable LiOH absorber for the advanced Portable Life Support System (PLSS) is reported. During EVA the ERCA uses a mechanism involving gas absorption into a liquid absorbent for the removal and storage of the metabolically produced CO2 and moisture. Following the EVA, the expended absorbent is regenerated onboard the Space Station by an electrochemical CO2 concentrator. The ERCA concept has the ability to effectively satisfy the high metabolic CO2 and moisture removal requirements of PLSS applications. This paper defines the ERCA concept and its advantages for the PLSS application, reviews breadboard test data, and presents physical characteristics of the breadboard and projected flight hardware.

  6. Biological treatment of a textile effluent after electrochemical oxidation of reactive dyes.

    PubMed

    Vilaseca, Mercè; Gutiérrez, Maria-Carmen; López-Grimau, Victor; López-Mesas, Montserrat; Crespi, Martí

    2010-02-01

    In this work, a synthetic textile effluent containing a reactive dye (C.I. Reactive Orange 4) was treated in an electrochemical cell with titanium covered by platinum oxide (Ti/PtOx) electrodes to remove color. The discolored effluent was mixed with other textile mill process effluents (scouring, bleaching, washing, etc.), according to the rate of each effluent in the mill, and was submitted to biological treatment (activated sludge plant). Two biological plants were run simultaneously to evaluate the influence of oxidant products generated during the electrochemical treatment. The final chemical oxygen demand (COD) removal in both plants was 65 to 72%. The yield of the activated sludge plants was not affected by the addition of 10% of the discolored dyeing effluent (even when oxidants products were not removed), which indicates that the previous electrochemical treatment do not produce inhibition effects on the biological plant. However, in the case of direct addition of the discolored effluent, the biological treatment plant required a longer adaptation period. In addition, the electrolytic respirometry tests showed that all the biodegradable organic matter was removed, which implies that the yield in organic matter removal was the maximum possible for this type of treatment. PMID:20183984

  7. Electrodeposition and electrochemical reduction of epitaxial metal oxide thin films and superlattices

    NASA Astrophysics Data System (ADS)

    He, Zhen

    The focus of this dissertation is the electrodeposition and electrochemical reduction of epitaxial metal oxide thin films and superlattices. The electrochemical reduction of metal oxides to metals has been studied for decades as an alternative to pyrometallurgical processes for the metallurgy industry. However, the previous work was conducted on bulk polycrystalline metal oxides. Paper I in this dissertation shows that epitaxial face-centered cubic magnetite (Fe3O4 ) thin films can be electrochemically reduced to epitaxial body-centered cubic iron (Fe) thin films in aqueous solution on single-crystalline Au substrates at room temperature. This technique opens new possibilities to produce special epitaxial metal/metal oxide heterojunctions and a wide range of epitaxial metallic alloy films from the corresponding mixed metal oxides. Electrodeposition, like biomineralization, is a soft solution processing method which can produce functional materials with special properties onto conducting or semiconducting solid surfaces. Paper II in this dissertation presents the electrodeposition of cobalt-substituted magnetite (CoxFe3-xO4, 0 of cobalt-substituted magnetite (CoxFe3-xO4, 0oxide (Co3O4) thin films on stainless steel and Au single-crystalline substrates. The crystalline Co3O4 thin films exhibit high catalytic activity towards the oxygen evolution reaction in an alkaline solution. A possible application of the electrodeposited Co 3O4 is the fabrication of highly active and low-cost photoanodes for photoelectrochemical water-splitting cells.

  8. Metallic nickel nitride nanosheets realizing enhanced electrochemical water oxidation.

    PubMed

    Xu, Kun; Chen, Pengzuo; Li, Xiuling; Tong, Yun; Ding, Hui; Wu, Xiaojun; Chu, Wangsheng; Peng, Zhenmeng; Wu, Changzheng; Xie, Yi

    2015-04-01

    Exploring efficient and inexpensive oxygen evolution reaction (OER) electrocatalysts is of great importance for various electrochemical energy storage and conversion technologies. Ni-based electrocatalysts have been actively pursued because of their promising activity and earth abundance. However, the OER efficiency for most of the developed Ni-based electrocatalysts has been intrinsically limited due to their low electrical conductivity and poor active site exposure yield. Herein, we report metallic Ni3N nanosheets as an efficient OER electrocatalyst for the first time. The first-principles calculations and electrical transport property measurements unravel that the Ni3N is intrinsically metallic, and the carrier concentration can be remarkably improved with dimensional confinement. The EXAFS spectra provide solid evidence that the Ni3N nanosheets have disordered structure resultant of dimensional reduction, which then could provide more active sites for OER. Benefiting from enhanced electrical conductivity with metallic behavior and atomically disordered structure, the Ni3N nanosheets realize intrinsically improved OER activity compared with bulk Ni3N and NiO nanosheets. Our finding suggests that metallic nitride nanosheets could serve as a new group of OER electrocatalysts with excellent property. PMID:25761452

  9. Electrochemically deposited gallium oxide nanostructures on silicon substrates

    NASA Astrophysics Data System (ADS)

    Ghazali, Norizzawati Mohd; Mahmood, Mohamad Rusop; Yasui, Kanji; Hashim, Abdul Manaf

    2014-03-01

    We report a synthesis of ?-Ga2O3 nanostructures on Si substrate by electrochemical deposition using a mixture of Ga2O3, HCl, NH4OH, and H2O. The presence of Ga3+ ions contributed to the deposition of Ga2O3 nanostructures on the Si surface with the assistance of applied potentials. The morphologies of the grown structures strongly depended on the molarity of Ga2O3 and pH level of electrolyte. ?-Ga2O3 nanodot-like structures were grown on Si substrate at a condition with low molarity of Ga2O3. However, Ga2O3 nanodot structures covered with nanorods on top of their surfaces were obtained at higher molarity, and the densities of nanorods seem to increase with the decrease of pH level. High concentration of Ga3+ and OH- ions may promote the reaction of each other to produce Ga2O3 nanorods in the electrolyte. Such similar nature of Ga2O3 nanorods was also obtained by using hydrothermal process. The grown structures seem to be interesting for application in electronic and optoelectronic devices as well as to be used as a seed structure for subsequent chemical synthesis of GaN by thermal transformation method.

  10. Electrochemically deposited gallium oxide nanostructures on silicon substrates.

    PubMed

    Ghazali, Norizzawati Mohd; Mahmood, Mohamad Rusop; Yasui, Kanji; Hashim, Abdul Manaf

    2014-01-01

    We report a synthesis of ?-Ga2O3 nanostructures on Si substrate by electrochemical deposition using a mixture of Ga2O3, HCl, NH4OH, and H2O. The presence of Ga3+ ions contributed to the deposition of Ga2O3 nanostructures on the Si surface with the assistance of applied potentials. The morphologies of the grown structures strongly depended on the molarity of Ga2O3 and pH level of electrolyte. ?-Ga2O3 nanodot-like structures were grown on Si substrate at a condition with low molarity of Ga2O3. However, Ga2O3 nanodot structures covered with nanorods on top of their surfaces were obtained at higher molarity, and the densities of nanorods seem to increase with the decrease of pH level. High concentration of Ga3+ and OH- ions may promote the reaction of each other to produce Ga2O3 nanorods in the electrolyte. Such similar nature of Ga2O3 nanorods was also obtained by using hydrothermal process. The grown structures seem to be interesting for application in electronic and optoelectronic devices as well as to be used as a seed structure for subsequent chemical synthesis of GaN by thermal transformation method. PMID:24629107

  11. High-temperature "spectrochronopotentiometry": correlating electrochemical performance with in situ Raman spectroscopy in solid oxide fuel cells.

    PubMed

    Kirtley, John D; Halat, David M; McIntyre, Melissa D; Eigenbrodt, Bryan C; Walker, Robert A

    2012-11-20

    Carbon formation or "coking" on solid oxide fuel cell (SOFC) anodes adversely affects performance by blocking catalytic sites and reducing electrochemical activity. Quantifying these effects, however, often requires correlating changes in SOFC electrochemical efficiency measured during operation with results from ex situ measurements performed after the SOFC has been cooled and disassembled. Experiments presented in this work couple vibrational Raman spectroscopy with chronopotentiometry to observe directly the relationship between graphite deposited on nickel cermet anodes and the electrochemical performance of SOFCs operating at 725 °C. Raman spectra from Ni cermet anodes at open circuit voltage exposed to methane show a strong vibrational band at 1556 cm(-1) assigned to the "G" mode of highly ordered graphite. When polarized in the absence of a gas-phase fuel, these carbon-loaded anodes operate stably, oxidizing graphite to form CO and CO(2). Disappearance of graphite intensity measured in the Raman spectra is accompanied by a steep ?0.8 V rise in the cell potential needed to keep the SOFC operating under constant current conditions. Continued operation leads to spectroscopically observable Ni oxidation and another steep rise in cell potential. Time-dependent spectroscopic and electrochemical measurements pass through correlated equivalence points providing unequivocal, in situ evidence that identifies how SOFC performance depends on the chemical condition of its anode. Chronopotentiometric data are used to quantify the oxide flux necessary to eliminate the carbon initially present on the SOFC anode, and data show that the oxidation mechanisms responsible for graphite removal correlate directly with the electrochemical condition of the anode as evidenced by voltammetry and impedance measurements. Electrochemically oxidizing the Ni anode damages the SOFC significantly and irreversibly. Anodes that have been reconstituted following electrochemical oxidation of carbon and Ni show qualitatively different kinetics of carbon removal, and the electrochemical performance of these systems is characterized by low maximum currents and large polarization resistances. PMID:23046116

  12. Lithium Isotope Effects Accompanying Electrochemical Insertion of Lithium into Metal Oxides

    Microsoft Academic Search

    Masahiro MOURI; Kei ASANO; Satoshi YANASE; Takao OI

    2007-01-01

    Lithium was electrochemically inserted into SnO2 and Fe2O3--SiO2 binary oxide from the mixed solution of ethylene carbonate and methyl ethyl carbonate containing 1 M LiClO4, and the lithium isotope effect accompanying the insertion was investigated. Tin(IV) oxide showed a slight selectivity towards the heavier isotope of lithium with the separation factor (S) ranging from 0.982 to 0.999 at 25°C. Fe2O3--SiO2

  13. An efficient CeO2 /CoSe2 Nanobelt composite for electrochemical water oxidation.

    PubMed

    Zheng, Ya-Rong; Gao, Min-Rui; Gao, Qiang; Li, Hui-Hui; Xu, Jie; Wu, Zhen-Yu; Yu, Shu-Hong

    2015-01-14

    CeO2 /CoSe2 nanobelt composite for electrochemical water oxidation: A new CeO2 /CoSe2 nanobelt composite is developed as a highly effective water oxidation electrocatalyst by growing CeO2 nanoparticle CoSe2 nanobelts in situ via a simple polyol reduction route. The constructed hybrid catalyst shows extremely high oxgen evolution reaction (OER) activity, even beyond the state-of-the-art RuO2 catalyst in alkaline media. PMID:25115699

  14. Biochemical and spectrophotometric significance of advanced oxidized protein products

    Microsoft Academic Search

    Chantal Capeillère-Blandin; Valérie Gausson; Béatrice Descamps-Latscha; Véronique Witko-Sarsat

    2004-01-01

    We previously described the presence of advanced oxidation protein products (AOPP), a novel marker of oxidative stress in the plasma of hemodialyzed patients (HD). The present study was carried out to further investigate how myeloperoxidase (MPO)-catalyzed reactions could contribute to AOPP generation in the plasma. First, patterns of plasma protein oxidation obtained after in vitro incubation of control plasma with

  15. Coupling digestion in a pilot-scale UASB reactor and electrochemical oxidation over BDD anode to treat diluted cheese whey.

    PubMed

    Katsoni, Alphathanasia; Mantzavinos, Dionissios; Diamadopoulos, Evan

    2014-11-01

    The efficiency of the anaerobic treatment of cheese whey (CW) at mesophilic conditions was investigated. In addition, the applicability of electrochemical oxidation as an advanced post-treatment for the complete removal of chemical oxygen demand (COD) from the anaerobically treated cheese whey was evaluated. The diluted cheese whey, having a pH of 6.5 and a total COD of 6 g/L, was first treated in a 600-L, pilot-scale up-flow anaerobic sludge blanket (UASB) reactor. The UASB process, which was operated for 87 days at mesophilic conditions (32?±?2 °C) at a hydraulic retention time (HRT) of 3 days, led to a COD removal efficiency between 66 and 97 %, while the particulate matter of the wastewater was effectively removed by entrapment in the sludge blanket of the reactor. When the anaerobic reactor effluent was post-treated over a boron-doped diamond (BDD) anode at 9 and 18 A and in the presence of NaCl as the supporting electrolyte, complete removal of COD was attained after 3-4 h of reaction. During electrochemical experiments, three groups of organochlorinated compounds, namely trihalomethanes (THMs), haloacetonitriles (HANs), and haloketons (HKs), as well as 1,2-dichloroethane (DCA) and chloropicrin were identified as by-products of the process; these, alongside free chlorine, are thought to increase the matrix ecotoxicity to Artemia salina. PMID:24793070

  16. Effect of the iridium oxide thin film on the electrochemical activity of platinum nanoparticles.

    PubMed

    Chen, Aicheng; La Russa, Daniel J; Miller, Brad

    2004-10-26

    The influence of the iridium oxide thin film on the electrocatalytic properties of platinum nanoparticles was investigated using the electro-oxidation of methanol and CO as a probe. The presence of the IrO(2) thin film leads to the homogeneous dispersion of Pt nanoparticles. For comparison, polycrystalline platinum and Pt nanoparticles dispersed on a Ti substrate in the absence of an IrO(2) layer (Ti/Pt) were also investigated in this study. Inverted and enhanced CO bipolar peaks were observed using an in situ electrochemical Fourier transform infrared technique during the methanol oxidation on the Pt nanoparticles dispersed on a Ti substrate. Electrochemical impedance studies showed that the charge transfer resistance was significantly lower for the Ti/IrO(2)/Pt electrode compared with that of the massive Pt and Ti/Pt nanoparticles. The presence of the IrO(2) thin film not only greatly increases the active surface area but also promotes CO oxidation at a much lower electrode potential, thus, significantly enhancing the electrocatalytic activity of Pt nanoparticles toward methanol electro-oxidation. PMID:15491204

  17. Conductive diamond electrochemical oxidation of caffeine-intensified biologically treated urban wastewater.

    PubMed

    Martín de Vidales, María J; Millán, María; Sáez, Cristina; Pérez, José F; Rodrigo, Manuel A; Cañizares, Pablo

    2015-10-01

    In this work, the usefulness of Conductive Diamond Electrochemical Oxidation (CDEO) to degrade caffeine in real urban wastewater matrixes was assessed. The oxidation of actual wastewater intensified with caffeine (from 1 to 100mgL(-1)) was studied, paying particular attention to the influence of the initial load of caffeine and the differences observed during the treatment of caffeine in synthetic wastewater. The results showed that CDEO is a technology that is capable of efficiently degrading this compound even at very low concentrations and that it can even be completely depleted. Profiles of the ionic species of S (SO4(2-)), N (NH4(+), NO3(-)) and Cl (ClO(-), ClO3(-) and ClO4(-)) were monitored and explained for plausible oxidation mechanisms. It was observed that the efficiency achieved is higher in the treatment of real wastewater than in the oxidation of synthetic wastewater because of the contribution of electrogenerated oxidant species such as hypochlorite. The formation of chlorate and perchlorate during electrochemical processes was observed, and a combined strategy to prevent this important drawback was successfully tested based on the application of low current densities with the simultaneous dosing of hydrogen peroxide. PMID:26048815

  18. Degradation of the commercial surfactant nonylphenol ethoxylate by advanced oxidation processes.

    PubMed

    da Silva, Salatiel Wohlmuth; Klauck, Cláudia Regina; Siqueira, Marco Antônio; Bernardes, Andréa Moura

    2015-01-23

    Four different oxidation process, namely direct photolysis (DP) and three advanced oxidation processes (heterogeneous photocatalysis - HP, eletrochemical oxidation - EO and photo-assisted electrochemical oxidation - PEO) were applied in the treatment of wastewater containing nonylphenol ethoxylate (NPnEO). The objective of this work was to determine which treatment would be the best option in terms of degradation of NPnEO without the subsequent generation of toxic compounds. In order to investigate the degradation of the surfactant, the processes were compared in terms of UV/Vis spectrum, mineralization (total organic carbon), reaction kinetics, energy efficiency and phytotoxicity. A solution containing NPnEO was prepared as a surrogate of the degreasing wastewater, was used in the processes. The results showed that the photo-assisted processes degrade the surfactant, producing biodegradable intermediates in the reaction. On the other hand, the electrochemical process influences the mineralization of the surfactant. The process of PEO carried out with a 250W lamp and a current density of 10mA/cm(2) showed the best results in terms of degradation, mineralization, reaction kinetics and energy consumption, in addition to not presenting phytotoxicity. Based on this information, this process can be a viable alternative for treating wastewater containing NPnEO, avoiding the contamination of water resources. PMID:25262384

  19. Electrochemical properties of tin oxide anodes for sodium-ion batteries

    NASA Astrophysics Data System (ADS)

    Lu, Ying Ching; Ma, Chuze; Alvarado, Judith; Kidera, Takafumi; Dimov, Nikolay; Meng, Ying Shirley; Okada, Shigeto

    2015-06-01

    Few tin (Sn)-oxide based anode materials have been found to have large reversible capacity for both sodium (Na)-ion and lithium (Li)-ion batteries. Herein, we report the synthesis and electrochemical properties of Sn oxide-based anodes for sodium-ion batteries: SnO, SnO2, and SnO2/C. Among them, SnO is the most suitable anode for Na-ion batteries with less first cycle irreversibility, better cycle life, and lower charge transfer resistance. The energy storage mechanism of the above-mentioned Sn oxides was studied, which suggested that the conversion reaction of the Sn oxide anodes is reversible in Na-ion batteries. The better anode performance of SnO is attributed by the better conductivity.

  20. Voltammetric Scanning Electrochemical Cell Microscopy: Dynamic Imaging of Hydrazine Electro-oxidation on Platinum Electrodes.

    PubMed

    Chen, Chang-Hui; Jacobse, Leon; McKelvey, Kim; Lai, Stanley C S; Koper, Marc T M; Unwin, Patrick R

    2015-06-01

    Voltammetric scanning electrochemical cell microscopy (SECCM) incorporates cyclic voltammetry measurements in the SECCM imaging protocol, by recording electrochemical currents in a wide potential window at each pixel in a map. This provides much more information compared to traditional fixed potential imaging. Data can be represented as movies (hundreds of frames) of current (over a surface region) at a series of potentials and are highly revealing of subtle variations in electrode activity. Furthermore, by combining SECCM data with other forms of microscopy, e.g. scanning electron microscopy and electron backscatter diffraction data, it is possible to directly relate the current-voltage characteristics to spatial position and surface structure. In this work we use a "hopping mode", where the SECCM pipet probe is translated toward the surface at a series of positions until meniscus contact. Small amounts of residue left on the surface, upon probe retraction, demark the precise area of each measurement. We use these techniques to study hydrazine oxidation on a polycrystalline platinum substrate both in air and in a deaerated environment. In both cases, the detected faradaic current shows a structural dependence on the surface crystallographic orientation. Significantly, in the presence of oxygen (aerated solution) the electrochemical current decreases strongly for almost all grains (crystallographic orientations). The results highlight the flexibility of voltammetric SECCM for electrochemical imaging and present important implications for hydrazine electroanalysis. PMID:25942527

  1. Effect of surfactant on the electrochemical performance of graphene/iron oxide electrode for supercapacitor

    NASA Astrophysics Data System (ADS)

    Ghasemi, Shahram; Ahmadi, Fatemeh

    2015-09-01

    In this study, reduced graphene oxide- Fe3O4 (RGO-Fe3O4) nanocomposite is fabricated using simple electrophoretic deposition (EPD) method followed by an electrochemical reduction process. It is characterized using atomic force microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy and scanning electron microscopy. Fe3O4 nanoparticles with 20-50 nm in diameter are uniformly formed on RGO. Electrochemical properties of nanocomposite are characterized by cyclic voltammetery, galvanostatic charge/discharge and electrochemical impedance spectroscopy. According to the galvanostatic charge/discharge analysis, RGO-Fe3O4/SS presents specific capacitance (Cs) of 154 F g-1 at current density of 1 A g-1, which is higher than that of RGO/SS (81 F g-1) in Na2SO4 electrolyte. Also, the electrochemical behaviors show that addition of three kind of surfactant, i.e. sodium dodecyl sulphate, cetyltrimethylammonium bromide, t-octyl phenoxy polyethoxyethanol (Triton X-100) to Na2SO4 aqueous solution can improve the Cs of RGO-Fe3O4/SS electrodes. RGO-Fe3O4/SS in Na2SO4 electrolyte containing Triton X-100 shows maximum Cs of 236 F g-1 at 1 A g-1 which retains 97% of initial capacitance after 500 cycles.

  2. Electrochemically-Controlled Compositional Oscillations of Oxide Surfaces

    SciTech Connect

    Mutoro, Eva [Massachusetts Institute of Technology (MIT); Crumlin, Ethan [Massachusetts Institute of Technology (MIT); Pöpke, Hendrik [Institute of Physical Chemistry, Justus-Liebig-University Giessen; Luerssen, Bjoern [Institute of Physical Chemistry, Justus-Liebig-University Giessen; Amati, Matteo [Sincrotrone Trieste Elettra; Abyaneh, Majid [Sincrotrone Trieste, Basovizza, Italy; Biegalski, Michael D [ORNL; Christen, Hans M [ORNL; Gregoratti, Luca [Sincrotrone Trieste, Basovizza, Italy; Janek, Jürgen [Institute of Physical Chemistry, Justus-Liebig-University Giessen; Shao-Horn, Yang [Massachusetts Institute of Technology (MIT)

    2012-01-01

    Perovskite oxides can exhibit a wide range of interesting characteristics such as being catalytically active and electronically and/or ionically conducting, and thus they have been used in a number of solid-state devices such as solid oxide fuel cells and sensors. As the surface compositions of perovskites can greatly influence the catalytic properties, knowing and controlling their surface chemistries is crucial to enhance device performance. In this study, we demonstrate that the surface strontium (Sr) and cobalt (Co) concentrations of perovskite-based thin films can be controlled reversibly at elevated temperatures by applying small electrical potential biases. The surface chemistry changes of La0.8Sr0.2CoO3 (LSC113), LaSrCoO4 (LSC214), and LSC214-decorated LSC113 films (LSC113/214) were investigated in situ by utilizing synchrotron-based X-ray photoelectron spectroscopy (XPS), where the largest changes of surface Sr was found for the LSC113/214 surface. These findings offer the potential of reversibly controlling the surface functionality of perovskites.

  3. Electrochemical properties of iodine-containing lithium manganese oxide spinel

    NASA Astrophysics Data System (ADS)

    Han, Chi-Hwan; Hong, Young-Sik; Hong, Hyun-Sil; Kim, Keon

    Iodine-containing, cation-deficient, lithium manganese oxides (ICCD-LMO) are prepared by reaction of MnO 2 with LiI. The MnO 2 is completely transformed into spinel-structured compounds with a nominal composition of Li 1- ?Mn 2-2 ?O 4I x. A sample prepared at 800 °C, viz. Li 0.99Mn 1.98O 4I 0.02, exhibits an initial discharge capacity of 113 mA h g -1 with good cycleability and rate capability in the 4-V region. Iodine-containing, lithium-rich lithium manganese oxides (ICLR-LMO) are also prepared by reaction of LiMn 2O 4 with LiI, which results in a nominal composition of Li 1+ xMn 2- xO 4I x. Li 1.01Mn 1.99O 4I 0.02 shows a discharge capacity of 124 mA h g -1 on the first cycle and 119 mA h g -1 a on the 20th cycle. Both results indicate that a small amount of iodine species helps to maintain cycle performance.

  4. Advanced EMU electrochemically regenerable CO2 and moisture absorber module breadboard

    NASA Technical Reports Server (NTRS)

    Lee, M. C.; Sudar, M.; Chang, B. J.

    1988-01-01

    The applicability of the Electrochemically Regenerable Carbon Dioxide and Moisture Absorption Technology to the advanced extravehicular mobility unit was demonstrated by designing, fabricating, and testing a breadboard Absorber Module and an Electrochemical Regenerator. Test results indicated that the absorber module meets or exceeds the carbon dioxide removal requirements specified for the design and can meet the moisture removal requirement when proper cooling is provided. CO2 concentration in the vent gas stream was reduced from 0.52 to 0.027 kPa (3.9 to 0.20 mm Hg) for the full five hour test period. Vent gas dew point was reduced from inlet values of 294 K (69 F) to 278 K (41 F) at the outlet. The regeneration of expended absorbent was achieved by the electrochemical method employed in the testing. An absorbent bed using microporous hydrophobic membrane sheets with circulating absorbent is shown to be the best approach to the design of an Absorber Module based on sizing and performance. Absorber Module safety design, comparison of various absorbents and their characteristics, moisture absorption and cooling study and subsystem design and operation time-lining study were also performed.

  5. Bio-functionalized graphene-graphene oxide nanocomposite based electrochemical immunosensing.

    PubMed

    Sharma, Priyanka; Tuteja, Satish K; Bhalla, Vijayender; Shekhawat, G; Dravid, Vinayak P; Suri, C Raman

    2013-01-15

    We report a novel in-situ electrochemical synthesis approach for the formation of functionalized graphene-graphene oxide (fG-GO) nanocomposite on screen-printed electrodes (SPE). Electrochemically controlled nanocomposite film formation was studied by transmission electron microscopy (TEM) and Raman spectroscopy. Further insight into the nanocomposite has been accomplished by the Fourier transformed infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA) and X-ray diffraction (XRD) spectroscopy. Configured as a highly responsive screen-printed immunosensor, the fG-GO nanocomposite on SPE exhibits electrical and chemical synergies of the nano-hybrid functional construct by combining good electronic properties of functionalized graphene (fG) and the facile chemical functionality of graphene oxide (GO) for compatible bio-interface development using specific anti-diuron antibody. The enhanced electrical properties of nanocomposite biofilm demonstrated a significant increase in electrochemical signal response in a competitive inhibition immunoassay format for diuron detection, promising its potential applicability for ultra-sensitive detection of range of target analytes. PMID:22884654

  6. Tunable bandgap of a single layer graphene doped by the manganese oxide using the electrochemical doping

    NASA Astrophysics Data System (ADS)

    Soo Park, Chang; Zhao, Yu; Lee, Jae-Hyun; Whang, Dongmok; Shon, Yoon; Song, Yoon-Ho; Jin Lee, Cheol

    2013-01-01

    We studied the control of the bandgap energy of graphene by doping manganese oxide nanoparticles using an electrochemical method. The manganese oxide doping into the graphene was a main role for the bandgap opening and the defect generation was an effective method to increase the density of Mn doping on the graphene. The measured bandgap increased and finally saturated at 0.256 eV as the concentration of manganese oxide nanoparticles increased. The bandgap energies were 0.22, 0.244, 0.250, and 0.256 eV at the applied voltage of 0.5, 1.0, 1.5, and 2.0 V, respectively. In addition, the defect generation by the plasma treatment resulted in improved formations of the bandgap energy up to 0.4 eV. The combination of the manganese oxide doping and the defect generation can enhance the bandgap energy effectively in the graphene. It is considered that the electrochemical doping technique is an effective way to control the bandgap energy of graphene.

  7. Arsenic(III) detection using electrochemical-chemical-chemical redox cycling at bare indium-tin oxide electrodes.

    PubMed

    Jeong, Jinkyo; Das, Jagotamoy; Choi, Moonjung; Jo, Jinkyung; Aziz, Md Abdul; Yang, Haesik

    2014-11-21

    Sensitive As(III) detection in ground water is of great importance for evaluating the quality of drinking water. We report a sensitive electrochemical method for As(III) detection based on electrochemical-chemical-chemical (ECC) redox cycling involving Ru(IV) [an oxidized species of Ru(III)(NH3)5NH2(2+)], As(III), and tris(3-carboxyethyl)phosphine (TCEP). Electrochemical oxidation of Ru(III)(NH3)5NH2(2+) formed from Ru(III)(NH3)6(3+) generates Ru(IV), which quickly oxidizes As(III). This electro-mediated oxidation of As(III) produces As(V), which is reduced back to As(III) by TCEP. Electrochemically generated Ru(IV) then reoxidizes As(III), allowing ECC redox cycling to occur at a high rate on bare indium-tin oxide (ITO) electrodes without modifying the surfaces with electrocatalytic materials. Because most interfering metal ions precipitate in a carbonate buffer, water samples are mixed with carbonate buffers prior to electrochemical measurements, rendering the effects of Cu(+), Cu(2+), Fe(2+), Fe(3+), and Pb(2+) insignificant. The detection limit calculated by ECC redox cycling using a chronocoulogram is 1.2 ?M, much lower than that obtained using only the electro-mediated oxidation of As(III) (90 ?M). PMID:25209319

  8. Influence of synthesis conditions on the electrochemical properties of nanostructured amorphous manganese oxide cryogels

    NASA Astrophysics Data System (ADS)

    Yang, Jingsi; Xu, Jun John

    Amorphous manganese oxides have received increasing attention in recent years as intercalation cathodes for rechargeable lithium batteries. The sol-gel method is a versatile method for achieving nanostructured amorphous oxides. In this paper, two different sol-gel routes are investigated, where nanostructured amorphous manganese oxide cryogels are obtained via freeze drying Mn(IV) oxide hydrogels formed in situ. In one route the hydrogels are formed by reaction between a solution of sodium permanganate and a solution of disodium fumarate, and in the other route by reaction between a solution of sodium permanganate and solid fumaric acid. Highly homogeneous monolithic manganese oxide hydrogels are obtained from both synthesis routes with precursor concentrations between 0.1 and 0.2 M. The freeze drying method proves to be an efficient method for obtaining nanostructured amorphous manganese oxide cryogels out of the hydrogels. Depending on the synthesis conditions of the hydrogels, the resultant cryogels can yield very high specific capacities for lithium intercalation and excellent rate performance. The cryogel with the best performance exhibits 289 mAh/g at a C/100 rate and 174 mAh/g at a 2 C rate. Strong dependence of electrochemical properties of the cryogels on the synthesis conditions of the parent hydrogels has been observed. The different electrochemical properties are believed to be due to different surface areas and local structures of the cryogels derived from hydrogels synthesized under different conditions. This strong dependence gives rise to the possibility of achieving promising intercalation materials through tailoring the surface area and the local structure of amorphous manganese oxides by adjusting sol-gel synthesis conditions.

  9. Facile and novel electrochemical preparation of a graphene-transition metal oxide nanocomposite for ultrasensitive electrochemical sensing of acetaminophen and phenacetin

    NASA Astrophysics Data System (ADS)

    Jiang, Lin; Gu, Shuqing; Ding, Yaping; Jiang, Feng; Zhang, Zhen

    2013-12-01

    A facile and novel preparation strategy based on electrochemical techniques for the fabrication of electrodeposited graphene (EGR) and zinc oxide (ZnO) nanocomposite was developed. The morphology and structure of the EGR-based nanocomposite were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (XPS) and Raman spectroscopy. Meanwhile, the electrochemical performance of the nanocomposite was demonstrated with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Due to the synergistic effect of EGR and ZnO nanoparticles, an ultrasensitive electrochemical sensor for acetaminophen (AC) and phenacetin (PCT) was successfully fabricated. The linearity ranged from 0.02 to 10 ?M for AC and 0.06 to 10 ?M for PCT with high sensitivities of 54 295.82 ?A mM-1 cm2 for AC and 21 344.66 ?A mM-1 cm2 for PCT, respectively. Moreover, the practical applicability was validated to be reliable and desirable in pharmaceutical detections. The excellent results showed the promise of the proposed preparation strategy of EGR-transition metal oxide nanocomposite in the field of electroanalytical chemistry.A facile and novel preparation strategy based on electrochemical techniques for the fabrication of electrodeposited graphene (EGR) and zinc oxide (ZnO) nanocomposite was developed. The morphology and structure of the EGR-based nanocomposite were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (XPS) and Raman spectroscopy. Meanwhile, the electrochemical performance of the nanocomposite was demonstrated with cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Due to the synergistic effect of EGR and ZnO nanoparticles, an ultrasensitive electrochemical sensor for acetaminophen (AC) and phenacetin (PCT) was successfully fabricated. The linearity ranged from 0.02 to 10 ?M for AC and 0.06 to 10 ?M for PCT with high sensitivities of 54 295.82 ?A mM-1 cm2 for AC and 21 344.66 ?A mM-1 cm2 for PCT, respectively. Moreover, the practical applicability was validated to be reliable and desirable in pharmaceutical detections. The excellent results showed the promise of the proposed preparation strategy of EGR-transition metal oxide nanocomposite in the field of electroanalytical chemistry. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03620k

  10. Sequential treatment of diluted olive pomace leachate by digestion in a pilot scale UASB reactor and BDD electrochemical oxidation.

    PubMed

    Katsoni, Alphathanasia; Mantzavinos, Dionissios; Diamadopoulos, Evan

    2014-06-15

    The efficiency of the anaerobic treatment of olive pomace leachate (OPL) at mesophilic conditions was investigated. Daily and cumulative biogas production was measured during the operational period. The maximum biogas flowrate was 65 L/d, of which 50% was methane. In addition, the applicability of electrochemical oxidation as an advanced post-treatment method for the complete removal of chemical oxygen demand (COD) from the anaerobically treated OPL was evaluated. The diluted OPL, having a pH of 6.5 and a total COD of 5 g/L, was first treated in a 600 L, pilot-scale up-flow anaerobic sludge blanket (UASB) reactor. The UASB reactor was operated for 71 days at mesophilic conditions (32 ± 2 °C) in a temperature-controlled environment at a hydraulic retention time of 3 days, and organic loading rates (OLR) between 0.33 and 1.67 g COD/(L.d). The UASB process led to a COD removal efficiency between 35 and 70%, while the particulate matter of the wastewater was effectively removed by entrapment in the sludge blanket of the reactor. When the anaerobic reactor effluent was post-treated over a boron-doped diamond (BDD) anode at 18 A and in the presence of 0.17% NaCl as the supporting electrolyte, complete removal of COD was attained after 7 h of treatment predominantly through total oxidation reactions. During electrochemical experiments, three groups of organo-chlorinated compounds, namely trihalomethanes (THMs), haloacetonitriles (HANs) and haloketons (HKs), as well as 1,2-dichloroethane (DCA) and chloropicrin were identified as by-products of the process; these, along with the residual chlorine are thought to increase the matrix ecotoxicity to Artemia salina. PMID:24704905

  11. Spinel lithium manganese oxide nanoparticles: unique molten salt synthesis strategy and excellent electrochemical performances.

    PubMed

    Wang, Xiong; Zhu, Juanjuan; Liu, Yingjie

    2009-11-01

    As a promising candidate cathode material, spinel lithium manganese oxide nanoparticles were successfully synthesized through a novel molten salt synthesis route at relatively low temperature, using manganese dioxide nanowires as precursor. A variety of techniques were applied to characterize the spinel nanomaterial, including X-ray diffraction, transmission electron microscopy, field-emission scanning electron microscopy, and X-ray photoelectron spectroscopy. The average particle size of the resulting spinel nanoparticles was about 80 nm with narrow distribution. As cathode material for rechargeable lithium ion battery, the electrochemical properties were investigated. All the results show that the electrochemical performances of the homogeneous spinel nanoparticles were improved, which might be ascribed to large specific surface area, fairly narrow size distribution, and the unique synthesis strategy. PMID:19908558

  12. Direct correlation of electrochemical behaviors with anti-thrombogenicity of semiconducting titanium oxide films.

    PubMed

    Wan, Guojiang; Lv, Bo; Jin, Guoshou; Maitz, Manfred F; Zhou, Jianzhang; Huang, Nan

    2014-01-01

    Biomaterials-associated thrombosis is dependent critically upon electrochemical response of fibrinogen on material surface. The relationship between the response and anti-thrombogenicity of biomaterials is not well-established. Titanium oxide appears to have good anti-thrombogenicity and little is known about its underlying essential chemistry. We correlate their anti-thrombogenicity directly to electrochemical behaviors in fibrinogen containing buffer solution. High degree of inherent n-type doping was noted to contribute the impedance preventing charge transfer from fibrinogen into film (namely its activation) and consequently reduced degree of anti-thrombogenicity. The impedance was the result of high donor carrier density as well as negative flat band potential. PMID:23413233

  13. Electrochemical characterization of lithiated transition metal oxide cathode particles in the absence of carbon, binders and other additives

    Microsoft Academic Search

    Dana A Totir; Boris D Cahan; Daniel A Scherson

    1999-01-01

    A novel method is herein described for the electrochemical characterization of lithiated transition metal oxides in powder form as cathode materials for lithium ion batteries. The procedure involves application of sufficiently high pressures to a layer of oxide powder evenly dispersed on the surface of a Au foil so as to embed the particles into the soft metal substrate, thereby

  14. Simultaneous Electrochemical Detection of Dopamine and Ascorbic Acid Using an Iron Oxide/Reduced Graphene Oxide Modified Glassy Carbon Electrode

    PubMed Central

    Peik-See, Teo; Pandikumar, Alagarsamy; Nay-Ming, Huang; Hong-Ngee, Lim; Sulaiman, Yusran

    2014-01-01

    The fabrication of an electrochemical sensor based on an iron oxide/graphene modified glassy carbon electrode (Fe3O4/rGO/GCE) and its simultaneous detection of dopamine (DA) and ascorbic acid (AA) is described here. The Fe3O4/rGO nanocomposite was synthesized via a simple, one step in-situ wet chemical method and characterized by different techniques. The presence of Fe3O4 nanoparticles on the surface of rGO sheets was confirmed by FESEM and TEM images. The electrochemical behavior of Fe3O4/rGO/GCE towards electrocatalytic oxidation of DA was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) analysis. The electrochemical studies revealed that the Fe3O4/rGO/GCE dramatically increased the current response against the DA, due to the synergistic effect emerged between Fe3O4 and rGO. This implies that Fe3O4/rGO/GCE could exhibit excellent electrocatalytic activity and remarkable electron transfer kinetics towards the oxidation of DA. Moreover, the modified sensor electrode portrayed sensitivity and selectivity for simultaneous determination of AA and DA. The observed DPVs response linearly depends on AA and DA concentration in the range of 1–9 mM and 0.5–100 ?M, with correlation coefficients of 0.995 and 0.996, respectively. The detection limit of (S/N = 3) was found to be 0.42 and 0.12 ?M for AA and DA, respectively. PMID:25195850

  15. Electrochemically regenerable metabolic CO2 and moisture control system for an advanced EMU application

    NASA Technical Reports Server (NTRS)

    Lee, M. C.; Beckstrom, P. S.; Cusick, R. J.

    1988-01-01

    Regenerable CO2 and moisture removal techniques that reduce expendables and logistics requirements are needed to sustain people undertaking extravehicular activities for the Space Station. NASA has been investigating ways to advance the Electrochemically Regenerable CO2 and Moisture Absorption (ERCA) technology to replace the nonregenerable solid lithium hydroxide absorber for the advanced Portable Life Support System (PLSS). The ERCA technology, due to its use of liquid absorbent, has the ability to effectively satisfy the high metabolic CO2 and moisture removal requirements of PLSS applications. This paper defines the ERCA technology concept and its advantages for the PLSS application, reviews breadboard and subscale testdata and presents the results of design concepts for a prototype Absorber Module of improved performance and the physical characteristics of the projected flight hardware.

  16. Recent advances in porous Pt-based nanostructures: synthesis and electrochemical applications.

    PubMed

    Xu, You; Zhang, Bin

    2014-04-21

    Porous Pt-based nanostructured materials possess intriguing physical and chemical properties to generate promising potential for various important applications such as fuel cells, sensors, stimulation electrodes, mechanical actuators and catalysis. With the great advances in material science and nanotechnology, porous Pt-based nanomaterials with well-controlled composition, shape, and geometrical configuration have been rationally designed and fabricated. Importantly, their superior properties including unique pore structure, large specific surface area and excellent structural stability have fuelled up great interest to improve their current performance and to explore new applications. This tutorial review attempts to summarize the recent important progress towards the development of porous Pt-based nanostructured materials, with special emphasis on fabrication methods and advanced electrochemical applications, such as electrocatalysis and electrochemical sensors. The correlations between the composition and morphology of the catalysts and their catalytic properties are discussed based on some important and representative examples. Some key scientific issues and potential future directions of research in this field are also discussed. PMID:24458336

  17. Enhanced catalytic and dopamine sensing properties of electrochemically reduced conducting polymer nanocomposite doped with pure graphene oxide.

    PubMed

    Wang, Wenting; Xu, Guiyun; Cui, Xinyan Tracy; Sheng, Ge; Luo, Xiliang

    2014-08-15

    Significantly enhanced catalytic activity of a nanocomposite composed of conducting polymer poly (3,4-ethylenedioxythiophene) (PEDOT) doped with graphene oxide (GO) was achieved through a simple electrochemical reduction process. The nanocomposite (PEDOT/GO) was electrodeposited on an electrode and followed by electrochemical reduction, and the obtained reduced nanocomposite (PEDOT/RGO) modified electrode exhibited lowered electrochemical impedance and excellent electrocatalytic activity towards the oxidation of dopamine. Based on the excellent catalytic property of PEDOT/RGO, an electrochemical sensor capable of sensitive and selective detection of DA was developed. The fabricated sensor can detect DA in a wide linear range from 0.1 to 175?M, with a detection limit of 39nM, and it is free from common interferences such as uric acid and ascorbic acid. PMID:24632460

  18. SULFATE RADICAL-BASED ADVANCED OXIDATION PROCESSES- ACS MEETING

    EPA Science Inventory

    This paper will present an overview of sulfate radical-based advanced oxidation technologies for the destruction of environmentally toxic chemicals in wastewater, industrial water, groundwater and sources of water supply. The paper will include fundamental aspects of the generati...

  19. Electrochemical behavior of indolone-N-oxides: relationship to structure and antiplasmodial activity.

    PubMed

    Reybier, Karine; Nguyen, Thi Hoang Yen; Ibrahim, Hany; Perio, Pierre; Montrose, Armelle; Fabre, Paul-Louis; Nepveu, Françoise

    2012-12-01

    Indolone-N-oxides exert high parasiticidal activity at the nanomolar level in vitro against Plasmodium falciparum, the parasite responsible for malaria. The bioreductive character of these molecules was investigated using cyclic voltammetry and EPR spectroelectrochemistry to examine the relationship between electrochemical behavior and antimalarial activity and to understand their mechanisms of action. For all the compounds (37 compounds) studied, the voltammograms recorded in acetonitrile showed a well-defined and reversible redox couple followed by a second complicated electron transfer. The first reduction (-0.88Voxide function to form a radical nitroxide anion. The second reduction (-1.65Velectrochemical behavior and indolone-N-oxide structure can be established for compounds with R(1)=-OCH(3), R(2)=H, and electron-withdrawing substituents on the phenyl group at R(3). The results help in the design of new molecules with more potent in vivo antimalarial activity. PMID:22771836

  20. Oxidation-Reduction Resistance of Advanced Copper Alloys

    NASA Technical Reports Server (NTRS)

    Greenbauer-Seng, L. (Technical Monitor); Thomas-Ogbuji, L.; Humphrey, D. L.; Setlock, J. A.

    2003-01-01

    Resistance to oxidation and blanching is a key issue for advanced copper alloys under development for NASA's next generation of reusable launch vehicles. Candidate alloys, including dispersion-strengthened Cu-Cr-Nb, solution-strengthened Cu-Ag-Zr, and ODS Cu-Al2O3, are being evaluated for oxidation resistance by static TGA exposures in low-p(O2) and cyclic oxidation in air, and by cyclic oxidation-reduction exposures (using air for oxidation and CO/CO2 or H2/Ar for reduction) to simulate expected service environments. The test protocol and results are presented.

  1. The electrochemical performance of thin-electrolyte solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Zurawski, D.; Kueper, T.

    1993-04-01

    Several benefits are realized by lowering the operating temperature of solid oxide fuel cells (SOFC's) from 1000C to temperatures in the 600 to 800C range. Among the advantages are decreased reaction between fuel cell components, shorter startup times, and the possibility of using metals in stack construction; however, the achievable power density in conventional SOFC's is too low. A strategy for overcoming this limitation is to decrease the thickness of this layer by approximately an order of magnitude. Thin (5 micron electrolyte SOFC's have recently been fabricated by Allied-Signal Aerospace Systems and Equipment Company (ASASE). The electrochemical performance of these cells has been studied and is discussed.

  2. Advanced oxidation processes (AOP) for water purification and recovery

    Microsoft Academic Search

    Roberto Andreozzi; Vincenzo Caprio; Amedeo Insola; Raffaele Marotta

    1999-01-01

    All advanced oxidation processes (AOP) are characterised by a common chemical feature: the capability of exploiting the high reactivity of HO radicals in driving oxidation processes which are suitable for achieving the complete abatement and through mineralization of even less reactive pollutants. The different AOP are considered and critically presented according to their specific features with reference, whenever possible, to

  3. Amplified electrochemical DNA-sensing of nanostructured metal oxide films deposited on disposable graphite electrodes functionalized by chemical vapor deposition

    Microsoft Academic Search

    Sanjay Mathur; Arzum Erdem; Christian Cavelius; Sven Barth; Jessica Altmayer

    2009-01-01

    Metal oxide nanostructures offer interesting possibilities to design functional surfaces for bio-sensing applications, for instance, through higher surface area leading to enhanced immobilization of biomolecules, which increases the detection limit. Herein, an amplified electrochemical sensing method has been presented for the detection of DNA based on the readout resulting from chemical oxidation of guanine on nanoscaled metal oxides (TiO2, SnO2

  4. Electrochemically reduced graphene oxide-based electrochemical sensor for the sensitive determination of ferulic acid in A. sinensis and biological samples.

    PubMed

    Liu, Linjie; Gou, Yuqiang; Gao, Xia; Zhang, Pei; Chen, Wenxia; Feng, Shilan; Hu, Fangdi; Li, Yingdong

    2014-09-01

    An electrochemically reduced graphene oxide (ERGO) modified glassy carbon electrode (GCE) was used as a new voltammetric sensor for the determination of ferulic acid (FA). The morphology and microstructure of the modified electrodes were characterized by scanning electron microscopy (SEM) and Raman spectroscopy analysis, and the electrochemical effective surface areas of the modified electrodes were also calculated by chronocoulometry method. Sensing properties of the electrochemical sensor were investigated by means of cyclic voltammetry (CV) and differential pulse voltammetry (DPV). It was found that ERGO was electrodeposited on the surface of GCE by using potentiostatic method. The proposed electrode exhibited electrocatalytic activity to the redox of FA because of excellent electrochemical properties of ERGO. The transfer electron number (n), electrode reaction rate constant (ks) and electron-transfer coefficient (?) were calculated as 1.12, 1.24s(-1), and 0.40, respectively. Under the optimized conditions, the oxidation peak current was proportional to FA concentration at 8.49 × 10(-8)mol L(-1) to 3.89 × 10(-5)mol L(-1) with detection limit of 2.06 × 10(-8)mol L(-1). This fabricated sensor also displayed acceptable reproducibility, long-term stability, and high selectivity with negligible interferences from common interfering species. The voltammetric sensor was successfully applied to detect FA in A. sinensis and biological samples with recovery values in the range of 99.91%-101.91%. PMID:25063114

  5. Electrochemical behavior and voltammetric determination of acetaminophen based on glassy carbon electrodes modified with poly(4-aminobenzoic acid)/electrochemically reduced graphene oxide composite films.

    PubMed

    Zhu, Wencai; Huang, Hui; Gao, Xiaochun; Ma, Houyi

    2014-12-01

    Poly(4-aminobenzoic acid)/electrochemically reduced graphene oxide composite film modified glassy carbon electrodes (4-ABA/ERGO/GCEs) were fabricated by a two-step electrochemical method. The electrochemical behavior of acetaminophen at the modified electrode was investigated by means of cyclic voltammetry. The results indicated that 4-ABA/ERGO composite films possessed excellent electrocatalytic activity towards the oxidation of acetaminophen. The electrochemical reaction of acetaminophen at 4-ABA/ERGO/GCE is proved to be a surface-controlled process involving the same number of protons and electrons. The voltammetric determination of acetaminophen performed with the 4-ABA/ERGO modified electrode presents a good linearity in the range of 0.1-65 ?M with a low detection limit of 0.01 ?M (S/N=3). In the case of using the 4-ABA/ERGO/GCE, acetaminophen and dopamine can be simultaneously determined without mutual interference. Furthermore, the 4-ABA/ERGO/GCE has good reproducibility and stability, and can be used to determine acetaminophen in tablets. PMID:25491797

  6. Electrochemical tuning of layered lithium transition metal oxides for improvement of oxygen evolution reaction

    NASA Astrophysics Data System (ADS)

    Lu, Zhiyi; Wang, Haotian; Kong, Desheng; Yan, Kai; Hsu, Po-Chun; Zheng, Guangyuan; Yao, Hongbin; Liang, Zheng; Sun, Xiaoming; Cui, Yi

    2014-07-01

    Searching for low-cost and efficient catalysts for the oxygen evolution reaction has been actively pursued owing to its importance in clean energy generation and storage. While developing new catalysts is important, tuning the electronic structure of existing catalysts over a wide electrochemical potential range can also offer a new direction. Here we demonstrate a method for electrochemical lithium tuning of catalytic materials in organic electrolyte for subsequent enhancement of the catalytic activity in aqueous solution. By continuously extracting lithium ions out of LiCoO2, a popular cathode material in lithium ion batteries, to Li0.5CoO2 in organic electrolyte, the catalytic activity is significantly improved. This enhancement is ascribed to the unique electronic structure after the delithiation process. The general efficacy of this methodology is demonstrated in several mixed metal oxides with similar improvements. The electrochemically delithiated LiCo0.33Ni0.33Fe0.33O2 exhibits a notable performance, better than the benchmark iridium/carbon catalyst.

  7. Electrochemical codeposition of vanadium oxide and polypyrrole for high-performance supercapacitor with high working voltage.

    PubMed

    Bai, Ming-Hua; Bian, Li-Jun; Song, Yu; Liu, Xiao-Xia

    2014-08-13

    Electrochemical codeposition of vanadium oxide (V2O5) and polypyrrole (PPy) is conducted from vanadyl sulfate (VOSO4) and pyrrole in their aqueous solution to get V2O5-PPy composite, during which one-dimensional growth of polypyrrole (PPy) is directed. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) are used to characterize the composite, while scanning electron microscopy (SEM) is used to investigate their morphologies. Cyclic voltammetry (CV), chronopotentiometry (CP) for galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS) are used to study electrochemical activities and pseudocapacitive properties of the composite. The influences of VOSO4 to pyrrole ratio in the electro-codeposition solution on morphologies and pseudocapacitive properties of the composite are discussed. Due to the organic-inorganic synergistic effect, V2O5-PPy composite exhibits good charge-storage properties in a large potential window from -1.4 to 0.6 V vs SCE, with a specific capacitance of 412 F/g at 4.5 mA/cm(2). A model supercapacitor assembled by using the V2O5-PPy composite as the electrode materials displays a high operating voltage of 2 V and so a high energy density of 82 Wh/kg (at the power density of 800 W/kg). PMID:25010464

  8. Laboratory and pilot plant scale study on the electrochemical oxidation of landfill leachate.

    PubMed

    Anglada, Angela; Urtiaga, Ana M; Ortiz, Inmaculada

    2010-09-15

    Kinetic data regarding COD oxidation were measured in a laboratory scale cell and used to scale-up an electro-oxidation process for landfill leachate treatment by means of boron-doped diamond anodes. A pilot-scale reactor with a total BDD anode area of 1.05 m(2) was designed. Different electrode gaps in the laboratory and pilot plant cells resulted in dissimilar reactor hydrodynamics. Consequently, generalised dimensionless correlations concerning mass transfer were developed in order to define the mass transfer conditions in both electrochemical systems. These correlations were then used in the design equations to validate the scale-up procedure. A series of experiments with biologically pre-treated landfill leachate were done to accomplish this goal. The evolution of ammonia and COD concentration could be well predicted. PMID:20542632

  9. Electrochemical and electrochromic properties of niobium oxide thin films fabricated by pulsed laser deposition

    SciTech Connect

    Fu, Z.W.; Kong, J.J.; Qin, Q.Z.

    1999-10-01

    Niobium oxide thin films have been successfully fabricated on the indium-tin oxide coated glasses by pulsed laser deposition in an O{sub 3}/O{sub 2} gas mixture. Films are characterized by X-ray diffraction and Raman spectrometry. Electrochemical and electrochromic properties of Nb{sub 2}O{sub 5} films are examined by cyclic voltammogram and potential step coupled with an in situ charge-coupled device spectrophotometer. The unique characteristics of absorption spectra of Nb{sub 2}O{sub 5} films are observed for the first time, and the optical absorption from the trapped electrons in the surface states plays an important role in the electrochromic phenomenon.

  10. Pilot treatment of olive pomace leachate by vertical-flow constructed wetland and electrochemical oxidation: an efficient hybrid process.

    PubMed

    Grafias, Petros; Xekoukoulotakis, Nikolaos P; Mantzavinos, Dionissios; Diamadopoulos, Evan

    2010-05-01

    A hybrid process comprising biological degradation in a vertical-flow constructed wetland (CW) and electrochemical oxidation over boron-doped diamond electrodes to decolorize, mineralize and detoxify a leachate from olive pomace processing (OPL) was investigated. Two alternative treatment schemes were compared: According to the first treatment scheme, OPL was treated by electrochemical oxidation followed by treatment in a constructed wetland pilot unit (CW-A). The second scheme comprised of treatment in a constructed wetland followed by electrochemical treatment (CW-B). The constructed wetlands units were planted with Phragmites australis (reeds) and were fed intermittently at organic loadings between 5 and 15 g COD m(-2) d(-1) and a residence time of 3 d. Electrochemical oxidation (EO) was performed for 360 min at 20 A. Treatment of OPL in the wetland at 15 g COD m(-2) d(-1) led to mean COD and color reduction of 86% and 77%, respectively; the wetland effluent with a COD of about 800 mg L(-1) was polished electrochemically for 360 min after which the overall COD and color removal of the combined process (i.e. CW-B/EO) was around 95%, while the final effluent was not toxic against the marine bacteria Vibrio fischeri. Electrochemical oxidation of the original OPL at COD values between 6250 and 14 100 mg L(-1) led to moderate COD and color reduction (i.e. less than 40%) through zero order kinetics. When this was coupled to constructed wetland post-treatment (i.e. EO/CW-A), the overall COD and color removal was 81% and 58%, respectively. The decreased efficiency may be assigned to the increased toxicity of the electrochemically treated effluent which was only partially removed in the natural treatment system. PMID:20199791

  11. Effect of nitro substituent on electrochemical oxidation of phenols at boron-doped diamond anodes.

    PubMed

    Jiang, Yi; Zhu, Xiuping; Li, Hongna; Ni, Jinren

    2010-02-01

    In order to investigate nitro-substitutent's effect on degradation of phenols at boron-doped diamond (BDD) anodes, cyclic voltammetries of three nitrophenol isomers: 2-nitrophenol (2NP), 3-nitrophenol (3NP) and 4-nitrophenol (4NP) were studied, and their bulk electrolysis results were compared with phenol's (Ph) under alkaline condition. The voltammetric study showed nitrophenols could be attacked by hydroxyl radicals and nitro-group was released from the aromatic ring. Results of bulk electrolysis showed degradation of all phenols were fit to a pseudo first-order equation and followed in this order: 2NP>4NP>3NP>Ph. Molecular structures, especially carbon atom charge, significantly influenced the electrochemical oxidation of these isomers. Intermediates were analyzed during the electrolysis process, and were mainly catechol, resorcinol, hydroquinone, and carboxylic acids, such as acetic acid and oxalic acid. A simple degradation pathway was proposed. Moreover, a linear increasing relationship between degradation rates and Hammett constants of the studied phenols was observed, which demonstrated that electrochemical oxidation of these phenols was mainly initiated by electrophilic attack of hydroxyl radicals at BDD anodes. PMID:20060999

  12. Bioactive plasma electrolytic oxidation coatings--the role of the composition, microstructure, and electrochemical stability.

    PubMed

    Mohedano, M; Guzman, R; Arrabal, R; López Lacomba, J-L; Matykina, E

    2013-11-01

    A Plasma electrolytic oxidation (PEO) process was used to produce bioactive coatings on Ti. PEO coatings with Ca/P atomic ratio of 1.7 and 4.0 were fabricated and characterized with respect to their morphology, composition, and microstructure. AC and DC electrochemical tests were used to evaluate the effect of (i) organic additives (amino acids, proteins, vitamins, and antibiotics) in alpha-minimum essential medium (?-MEM) on electrochemical stability of noncoated and PEO-coated Ti and (ii) coating composition, microstructure, and corrosion behavior on the cell response in ?-MEM. PEO-coated Ti showed higher corrosion resistance than the noncoated Ti in MEM with and without organic additives by an order of magnitude. The corrosion resistance in ?-MEM decreased with time for nonmodified Ti and increased for PEO-coated Ti; the latter was because of the adsorption of the proteins in the coating pores which increased the diffusion resistance. The presence of Ca and P in titanium oxide coating at the Ca/P ratio exceeding that of any stoichiometric Ca-P-O and Ca-P-O-H compounds facilitates faster osteoblast cell adhesion. PMID:23744783

  13. Selective oxidation of ethane using the Au|YSZ|Ag electrochemical membrane system

    SciTech Connect

    Hamakawa, Satoshi; Sato, Koichi; Hayakawa, Takashi; York, A.P.E.; Tsunoda, Tatsuo; Suzuki, Kunio; Shimizu, Masao; Takehira, Katsuomi [National Inst. of Materials and Chemical Research, Tsukuba, Ibaraki (Japan). Tsukuba Research Center

    1997-01-01

    The catalytic conversion of ethane to acetaldehyde on an inert gold electrode has been studied using the electrochemical membrane reactor with yttria-stabilized zirconia (YSZ) solid electrolyte at 475 C. On applying a direct current to the reaction cell, 5% ethane in N{sub 2}, Au|YSZ|Ag, 100% O{sub 2}, acetaldehyde was formed and the formation rate increased linearly with increasing current. Selectivities to acetaldehyde and carbon dioxide were 45 and 55%, respectively. The addition of oxygen to the ethane-mixed gas in the anode space did not affect the acetaldehyde formation. The use of YSZ powder as a fixed bed catalyst under the mixed gas flow of ethane and oxygen at 450 to 600 C resulted in the formation of carbon monoxide, carbon dioxide, and ethene. Even the use of N{sub 2}O instead of oxygen resulted in no formation of acetaldehyde. Hence, it is likely that partial oxidation of ethane to acetaldehyde was carried out by the oxygen species transferred electrochemically through the YSZ which appeared at the gold-YSZ-gas triple-phase boundary. From the results of ethanol oxidation over the Au|YSZ|Ag system, the following mechanism was proposed: ethane is dehydrogenated to an ethyl radical, then converted to ethoxide, and finally to acetaldehyde by the oxygen species transferred through the YSZ.

  14. New advanced surface modification technique: titanium oxide ceramic surface implants: long-term clinical results

    NASA Astrophysics Data System (ADS)

    Szabo, Gyorgy; Kovacs, Lajos; Barabas, Jozsef; Nemeth, Zsolt; Maironna, Carlo

    2001-11-01

    The purpose of this paper is to discuss the background to advanced surface modification technologies and to present a new technique, involving the formation of a titanium oxide ceramic coating, with relatively long-term results of its clinical utilization. Three general techniques are used to modify surfaces: the addition or removal of material and the change of material already present. Surface properties can also be changed without the addition or removal of material, through the laser or electron beam thermal treatment. The new technique outlined in this paper relates to the production of a corrosion-resistant 2000-2500 A thick, ceramic oxide layer with a coherent crystalline structure on the surface of titanium implants. The layer is grown electrochemically from the bulk of the metal and is modified by heat treatment. Such oxide ceramic-coated implants have a number of advantageous properties relative to implants covered with various other coatings: a higher external hardness, a greater force of adherence between the titanium and the oxide ceramic coating, a virtually perfect insulation between the organism and the metal (no possibility of metal allergy), etc. The coated implants were subjected to various physical, chemical, electronmicroscopic, etc. tests for a qualitative characterization. Finally, these implants (plates, screws for maxillofacial osteosynthesis and dental root implants) were applied in surgical practice for a period of 10 years. Tests and the experience acquired demonstrated the good properties of the titanium oxide ceramic-coated implants.

  15. New innovative materials for advanced electrochemical applications in battery and fuel cell systems

    NASA Astrophysics Data System (ADS)

    Voß, S.; Kollmann, H.; Kollmann, W.

    The advanced material POLYMET is an innovative high tech polymer with a three-dimensional polymeric structure metallized with an enclosing coating of different kinds of metals or alloys. The result is a range of tailor-made, microporous structures on a designable scale. By varying the metals and alloys, it is possible to draw upon extremely diverse areas of applications such as battery systems, fuel cells, filters or efficient catalysts as well as air regeneration systems, e.g. in aerospace. The three-dimensional structure of metallized high tech woven or non-woven materials or foams causes a lot of advantages such as high conductivity, high corrosion resistance, flexibility or mechanical strength. Therefore, POLYMET is suitable for, e.g. current collectors or gas diffusion layers in energy storage systems. They supply an economic and environmental alternative material to improve functional electrochemical systems.

  16. Influences of graphene oxide support on the electrochemical performances of graphene oxide-MnO2 nanocomposites

    PubMed Central

    2011-01-01

    MnO2 supported on graphene oxide (GO) made from different graphite materials has been synthesized and further investigated as electrode materials for supercapacitors. The structure and morphology of MnO2-GO nanocomposites are characterized by X-ray diffraction, X-ray photoemission spectroscopy, scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and Nitrogen adsorption-desorption. As demonstrated, the GO fabricated from commercial expanded graphite (denoted as GO(1)) possesses more functional groups and larger interplane gap compared to the GO from commercial graphite powder (denoted as GO(2)). The surface area and functionalities of GO have significant effects on the morphology and electrochemical activity of MnO2, which lead to the fact that the loading amount of MnO2 on GO(1) is much higher than that on GO(2). Elemental analysis performed via inductively coupled plasma optical emission spectroscopy confirmed higher amounts of MnO2 loading on GO(1). As the electrode of supercapacitor, MnO2-GO(1) nanocomposites show larger capacitance (307.7 F g-1) and better electrochemical activity than MnO2-GO(2) possibly due to the high loading, good uniformity, and homogeneous distribution of MnO2 on GO(1) support. PMID:21951643

  17. Study and characterization of porous copper oxide produced by electrochemical anodization for radiometric heat absorber

    PubMed Central

    2014-01-01

    The aim of this work is to optimize the different parameters for realization of an absorbing cavity to measure the incident absolute laser energy. Electrochemical oxidation is the background process that allowed the copper blackening. A study of the blackened surface quality was undertaken using atomic force microscopy (AFM) analysis and ultraviolet-visible-infrared spectrophotometry using a Shimadzu spectrophotometer. A two-dimensional and three-dimensional visualization by AFM of the formed oxide coating showed that the copper surfaces became porous after electrochemical etching with different roughness. This aspect is becoming more and more important with decreasing current density anodization. In a 2 mol L -1 of NaOH solution, at a temperature of 90°C, and using a 16 mA cm2 constant density current, the copper oxide formed has a reflectivity of around 3% in the spectral range between 300 and 1,800 nm. Using the ‘mirage effect’ technique, the obtained Cu2O diffusivity and thermal conductivity are respectively equal to (11.5?±?0.5) 10 to 7 m2 s-1 and (370?±?20) Wm-1 K-1. This allows us to consider that our Cu2O coating is a good thermal conductor. The results of the optical and thermal studies dictate the choice of the cavity design. The absorbing cavity is a hollow cylinder machined to its base at an angle of 30°. If the included angle of the plane is 30° and the interior surface gives specular reflection, an incoming ray parallel to the axis will undergo five reflections before exit. So the absorption of the surface becomes closely near 0.999999. PMID:25349555

  18. Mediated electrochemical oxidation treatment for Rocky Flats combustible low-level mixed waste. Final report, FY 1993 and 1994

    SciTech Connect

    Chiba, Z.; Lewis, P.R.; Murguia, L.C.

    1994-09-01

    Mediated Electrochemical Oxidation (MEO) is an aqueous process which destroys hazardous organics by oxidizing a mediator at the anode of an electrochemical cell; the mediator in turn oxidizes the organics within the bulk of the electrolyte. With this process organics can be nearly completely destroyed, that is, the carbon and hydrogen present in the hydrocarbon are almost entirely mineralized to carbon dioxide and water. The MEO process is also capable of dissolving radioactive materials, including difficult-to-dissolve compounds such as plutonium oxide. Hence, this process can treat mixed wastes, by destroying the hazardous organic components of the waste, and dissolving the radioactive components. The radioactive material can be recovered if desired, or disposed of as non-mixed radioactive waste. The process is inherently safe, since the hazardous and radioactive materials are completely contained in the aqueous phase, and the system operates at low temperatures (below 80{degree}C) and at ambient pressures.

  19. Effect of host–guest versus core–shell structure on electrochemical characteristics of vanadium oxide\\/polypyrrole nanocomposites

    Microsoft Academic Search

    Oleg Yu. Posudievsky; Olga A. Kozarenko; Vyacheslav S. Dyadyun; Scott W. Jorgensen; James A. Spearot; Vyacheslav G. Koshechko; Vitaly D. Pokhodenko

    Reduction in cost of lithium ion batteries is essential to the cost walk of electrified vehicles. Electrode microstructure can significantly affect capacity and thus cost. The effect of structure – host–guest versus core–shell – on electrochemical characteristics of transition metal oxide\\/conducting polymer nanocomposites as the active component of the positive electrode of lithium batteries was studied using two types of

  20. Selective adsorption toward toxic metal ions results in selective response: electrochemical studies on a polypyrrole/reduced graphene oxide nanocomposite.

    PubMed

    Zhao, Zhi-Qiang; Chen, Xing; Yang, Qing; Liu, Jin-Huai; Huang, Xing-Jiu

    2012-02-21

    Highly selective adsorption of a polypyrrole/reduced graphene oxide nanocomposite toward Hg(2+) results in electrochemically selective detection of Hg(2+). This interesting finding is of practical utility compared to the biotechniques and surface functionalization-based methods. PMID:22158837

  1. Use of high-temperature gas-tight electrochemical cells to measure electronic transport and thermodynamics in metal oxides

    Microsoft Academic Search

    J. H. Park; B. Ma; E. T. Park

    1997-01-01

    By using a gas-tight electrochemical cell, the authors can perform high-temperature coulometric titration and measure electronic transport properties to determine the electronic defect structure of metal oxides. This technique reduces the time and expense required for conventional thermogravimetric measurements. The components of the gas-tight coulometric titration cell are an oxygen sensor, Pt\\/yttria stabilized zirconia (YSZ)\\/Pt, and an encapsulated metal oxide

  2. Treatment of gasoline-contaminated waters by advanced oxidation processes

    Microsoft Academic Search

    Elaine Regina Lopes Tiburtius; Patricio Peralta-Zamora; Alexandre Emmel

    2005-01-01

    In this study, the efficiency of advanced oxidative processes (AOPs) was investigated toward the degradation of aqueous solutions containing benzene, toluene and xylenes (BTX) and gasoline-contaminated waters. The results indicated that BTX can be effectively oxidized by near UV-assisted photo-Fenton process. The treatment permits almost total degradation of BTX and removal of more than 80% of the phenolic intermediates at

  3. Behavior of molybdenum nitrides as materials for electrochemical capacitors: Comparison with ruthenium oxide

    SciTech Connect

    Liu, T.C.; Pell, W.G.; Conway, B.E. [Univ. of Ottawa, Ontario (Canada). Dept. of Chemistry; Roberson, S.L. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Materials Science and Engineering

    1998-06-01

    Ruthenium oxide (RuO{sub 2}), formed as a thin film on a Ru or Ti metal substrate, exhibits a large specific (cm{sup {minus}2}) and almost constant, electrochemical capacitance over a 1.35 V range in aqueous H{sub 2}SO{sub 4}. This behavior has led to its investigation and use as a material for fabrication of supercapacitor devices. However, its cost has encouraged search for other materials exhibiting similar behavior. Work reported in the present paper evaluates two nitrides of Mo, Mo{sub 2}N and MoN, as substitutes for RuO{sub 2}. It is shown that very similar capacitance behavior to that of RuO{sub 2} films arises, e.g., in cyclic voltammetry and dc charging curves; in the former, almost mirror-image anodic and cathodic current-response profiles, characteristic of a capacitor, arise. However, the nitride materials have a substantially smaller voltage operating range of only some 0.7 V due to electrochemical decomposition above ca. 0.7 V vs. RHE. This limits their usefulness as a substitute for RuO{sub 2}. Of interest is that the nitride films exhibit potential-decay and potential-recovery on open circuit after respective charge and forced discharge. The decay and recovery processes are logarithmic in time, indicating the role of internal faradaic charge redistribution processes.

  4. Exhaled nitric oxide monitoring by quantum cascade laser: comparison with chemiluminescent and electrochemical sensors

    NASA Astrophysics Data System (ADS)

    Mandon, Julien; Högman, Marieann; Merkus, Peter J. F. M.; van Amsterdam, Jan; Harren, Frans J. M.; Cristescu, Simona M.

    2012-01-01

    Fractional exhaled nitric oxide (FENO) is considered an indicator in the diagnostics and management of asthma. In this study we present a laser-based sensor for measuring FENO. It consists of a quantum cascade laser (QCL) combined with a multi-pass cell and wavelength modulation spectroscopy for the detection of NO at the sub-part-per-billion by volume (ppbv, 1?10-9) level. The characteristics and diagnostic performance of the sensor were assessed. A detection limit of 0.5 ppbv was demonstrated with a relatively simple design. The QCL-based sensor was compared with two market sensors, a chemiluminescent analyzer (NOA 280, Sievers) and a portable hand-held electrochemical analyzer (MINO®, Aerocrine AB, Sweden). FENO from 20 children diagnosed with asthma and treated with inhaled corticosteroids were measured. Data were found to be clinically acceptable within 1.1 ppbv between the QCL-based sensor and chemiluminescent sensor and within 1.7 ppbv when compared to the electrochemical sensor. The QCL-based sensor was tested on healthy subjects at various expiratory flow rates for both online and offline sampling procedures. The extended NO parameters, i.e. the alveolar region, airway wall, diffusing capacity, and flux were calculated and showed a good agreement with the previously reported values.

  5. Thromboresistant/anti-biofilm catheters via electrochemically modulated nitric oxide release.

    PubMed

    Ren, Hang; Colletta, Alessandro; Koley, Dipankar; Wu, Jianfeng; Xi, Chuanwu; Major, Terry C; Bartlett, Robert H; Meyerhoff, Mark E

    2015-08-01

    Inexpensive nitric oxide (NO) release strategies to prevent thrombosis and bacterial infections are desirable for implantable medical devices. Herein, we demonstrate the utility of electrochemically modulated NO release from a catheter model using an inner copper wire working electrode and an inorganic nitrite salt solution reservoir. These catheters generate NO surface fluxes of >1.0×10(-10)molmin(-1)cm(-2) for more than 60h. Catheters with an NO flux of 1.1×10(-10)molmin(-1)cm(-2) are shown to significantly reduce surface thrombus formation when implanted in rabbit veins for 7h. Further, the ability of these catheters to exhibit anti-biofilm properties against bacterial species commonly causing bloodstream and urinary catheter infections is examined. Catheters releasing NO continuously during the 2d growth of Staphylococcus aureus exhibit a 6 log-unit reduction in viable surface bacteria. We also demonstrate that catheters generating NO for only 3h at a flux of 1.0×10(-10)molmin(-1)cm(-2) lower the live bacterial counts of both 2d and 4d pre-formed Escherichia coli biofilms by >99.9%. Overall, the new electrochemical NO-release devices could provide a cost-effective strategy to greatly enhance the biocompatibility and antimicrobial properties of intravascular and urinary catheters, as well as other implantable medical devices. PMID:25588885

  6. Exhaled nitric oxide monitoring by quantum cascade laser: comparison with chemiluminescent and electrochemical sensors.

    PubMed

    Mandon, Julien; Högman, Marieann; Merkus, Peter J F M; van Amsterdam, Jan; Harren, Frans J M; Cristescu, Simona M

    2012-01-01

    Fractional exhaled nitric oxide (F(E)NO) is considered an indicator in the diagnostics and management of asthma. In this study we present a laser-based sensor for measuring F(E)NO. It consists of a quantum cascade laser (QCL) combined with a multi-pass cell and wavelength modulation spectroscopy for the detection of NO at the sub-part-per-billion by volume (ppbv, 110(-9)) level. The characteristics and diagnostic performance of the sensor were assessed. A detection limit of 0.5 ppbv was demonstrated with a relatively simple design. The QCL-based sensor was compared with two market sensors, a chemiluminescent analyzer (NOA 280, Sievers) and a portable hand-held electrochemical analyzer (MINO, Aerocrine AB, Sweden). F(E)NO from 20 children diagnosed with asthma and treated with inhaled corticosteroids were measured. Data were found to be clinically acceptable within 1.1 ppbv between the QCL-based sensor and chemiluminescent sensor and within 1.7 ppbv when compared to the electrochemical sensor. The QCL-based sensor was tested on healthy subjects at various expiratory flow rates for both online and offline sampling procedures. The extended NO parameters, i.e. the alveolar region, airway wall, diffusing capacity, and flux were calculated and showed a good agreement with the previously reported values. PMID:22352669

  7. Electrochemical Encyclopedia

    NSDL National Science Digital Library

    This site contains a compendium of 44 articles in electrochemistry. The articles cover a number of different topics including electrochemical capacitors, the electrochemistry of plant life, solid oxide fuel cells and electrolytic capacitors.

  8. Titanium Anodes with Active Coatings Based on Iridium Oxides: The Corrosion Resistance and Electrochemical Behavior of Anodes Coated by Mixed Iridium, Ruthenium, and Titanium Oxides

    Microsoft Academic Search

    V. V. Gorodetskii; V. A. Neburchilov

    2005-01-01

    A study of the corrosion resistance and electrochemical behavior of titanium anodes with active coatings prepared from mixed oxides iridium, ruthenium, and titanium (OIRTA) is continued. The dependence of the catalytic activity, selectivity, and corrosion resistance of these anodes with x mol % RuO2 + (30 ? x ) mol % IrO2 + 70 mol % TiO2 is studied in

  9. Advanced Oxidation Technology for Pulp Mill Effluent 

    E-print Network

    Hart, J. R.

    1992-01-01

    or UV radiation with ozone. The simplest AOP, however, is using ozone at a high pH. Hydrogen peroxide (H202) is added with ozone to the effluent stream to increase the formation of hydroxyl radicals. The decomposition of ozone is enhanced... with the result that the ozone oxidation reaction is accelerated. In addition, certain reaction rates with various organic compounds indicate a dependence on the hydrogen peroxide concentration. When UV radiation is used in combination with ozone, hydrogen...

  10. Redox activity of surface oxygen anions in oxygen-deficient perovskite oxides during electrochemical reactions.

    PubMed

    Mueller, David N; Machala, Michael L; Bluhm, Hendrik; Chueh, William C

    2015-01-01

    Surface redox-active centres in transition-metal oxides play a key role in determining the efficacy of electrocatalysts. The extreme sensitivity of surface redox states to temperatures, to gas pressures and to electrochemical reaction conditions renders them difficult to investigate by conventional surface-science techniques. Here we report the direct observation of surface redox processes by surface-sensitive, operando X-ray absorption spectroscopy using thin-film iron and cobalt perovskite oxides as model electrodes for elevated-temperature oxygen incorporation and evolution reactions. In contrast to the conventional view that the transition metal cations are the dominant redox-active centres, we find that the oxygen anions near the surface are a significant redox partner to molecular oxygen due to the strong hybridization between oxygen 2p and transition metal 3d electronic states. We propose that a narrow electronic state of significant oxygen 2p character near the Fermi level exchanges electrons with the oxygen adsorbates. This result highlights the importance of surface anion-redox chemistry in oxygen-deficient transition-metal oxides. PMID:25598003

  11. Reversible oxygen scavenging at room temperature using electrochemically reduced titanium oxide nanotubes.

    PubMed

    Close, Thomas; Tulsyan, Gaurav; Diaz, Carlos A; Weinstein, Steven J; Richter, Christiaan

    2015-05-01

    A material capable of rapid, reversible molecular oxygen uptake at room temperature is desirable for gas separation and sensing, for technologies that require oxygen storage and oxygen splitting such as fuel cells (solid-oxide fuel cells in particular) and for catalytic applications that require reduced oxygen species (such as removal of organic pollutants in water and oil-spill remediation). To date, however, the lowest reported temperature for a reversible oxygen uptake material is in the range of 200-300?°C, achieved in the transition metal oxides SrCoOx (ref. 1) and LuFe2O4+x (ref. 2) via thermal cycling. Here, we report rapid and reversible oxygen scavenging by TiO2-x nanotubes at room temperature. The uptake and release of oxygen is accomplished by an electrochemical rather than a standard thermal approach. We measure an oxygen uptake rate as high as 14?mmol O2?g(-1)?min(-1), ?2,400 times greater than commercial, irreversible oxygen scavengers. Such a fast oxygen uptake at a remarkably low temperature suggests a non-typical mechanistic pathway for the re-oxidation of TiO2-x. Modelling the diffusion of oxygen, we show that a likely pathway involves 'exceptionally mobile' interstitial oxygen produced by the oxygen adsorption and decomposition dynamics, recently observed on the surface of anatase. PMID:25849789

  12. Reversible oxygen scavenging at room temperature using electrochemically reduced titanium oxide nanotubes

    NASA Astrophysics Data System (ADS)

    Close, Thomas; Tulsyan, Gaurav; Diaz, Carlos A.; Weinstein, Steven J.; Richter, Christiaan

    2015-05-01

    A material capable of rapid, reversible molecular oxygen uptake at room temperature is desirable for gas separation and sensing, for technologies that require oxygen storage and oxygen splitting such as fuel cells (solid-oxide fuel cells in particular) and for catalytic applications that require reduced oxygen species (such as removal of organic pollutants in water and oil-spill remediation). To date, however, the lowest reported temperature for a reversible oxygen uptake material is in the range of 200–300?°C, achieved in the transition metal oxides SrCoOx (ref. 1) and LuFe2O4+x (ref. 2) via thermal cycling. Here, we report rapid and reversible oxygen scavenging by TiO2?x nanotubes at room temperature. The uptake and release of oxygen is accomplished by an electrochemical rather than a standard thermal approach. We measure an oxygen uptake rate as high as 14?mmol O2?g?1?min?1, ?2,400 times greater than commercial, irreversible oxygen scavengers. Such a fast oxygen uptake at a remarkably low temperature suggests a non-typical mechanistic pathway for the re-oxidation of TiO2?x. Modelling the diffusion of oxygen, we show that a likely pathway involves ‘exceptionally mobile’ interstitial oxygen produced by the oxygen adsorption and decomposition dynamics, recently observed on the surface of anatase.

  13. Detoxification of methyl-parathion pesticide in aqueous solutions by electrochemical oxidation.

    PubMed

    Arapoglou, D; Vlyssides, A; Israilides, C; Zorpas, A; Karlis, P

    2003-03-17

    Commercial methyl-parathion (MeP) was detoxified using an electrochemical method that employed a Ti/Pt anode and stainless steel 304 as cathode. Sodium chloride was added as electrolyte and the mixture was passed through an electrolytic cell for 2 h. Due to the strong oxidizing potential of the produced chemicals, the organic pollutants were wet oxidized to carbon dioxide and water. A number of experiments were run at laboratory scale. Reductions of COD and BOD(5) were both over 80% and the mean energy consumption was 18-8 kWh per kg(-1) COD reduced (COD(r)). The degradation of MeP was more effective when the pH of the brine solution was in the acid range than when it was in the alkaline range. From the results it can be concluded that electrolysis could be used as an oxidation pre-treatment stage for detoxification of toxic wastes with MeP. PMID:12628787

  14. Pretreatment of penicillin formulation effluent by advanced oxidation processes

    Microsoft Academic Search

    Idil Arslan-Alaton; Serdar Dogruel

    2004-01-01

    A variety of advanced oxidation processes (AOPs; O3\\/OH?, H2O2\\/UV, Fe2+\\/H2O2, Fe3+\\/H2O2, Fe2+\\/H2O2\\/UV and Fe3+\\/H2O2\\/UV) have been applied for the oxidative pre-treatment of real penicillin formulation effluent (average COD0=1395mg\\/L; TOC0=920mg\\/L; BOD5,0?0mg\\/L). For the ozonation process the primary involvement of free radical species such as OH in the oxidative reaction could be demonstrated via inspection of ozone absorption rates. Alkaline ozonation and

  15. A Novel Electrochemical Detector using Prussian Blue Modified Indium Tin Oxide Electrode

    NASA Astrophysics Data System (ADS)

    Yi, In-Je; Kim, Ju-Ho; Kang, C. J.; Choi, Y. J.; Lee, Kisay; Kim, Yong-Sang

    2006-01-01

    We propose a novel electrochemical detector (ECD) to catalyze redox efficiently by electrodepositing Prussian blue (PB, ferric hexacyanoferrate) on the indium tin oxide (ITO) electrode. Capillary electrophoresis (CE) and amperometric methods were used. We investigated the PB surface properties by topography from atomic force microscopy (AFM). The PB film on dense and smooth surfaces could catalyze redox reaction efficiently. Compared with CE-ECD microchips using a bare-ITO electrode, the proposed CE-ECD microchip using a PB modified electrode has shown better sensitivity of the electropherograms. It has been verified that wide-ranging detection can be performed under the limits of 0.01 mM of dopamine and catechol respectively when we use a PB modified electrode.

  16. Indium tin oxide based chip for optical and electrochemical characterization of protein–cell interaction

    NASA Astrophysics Data System (ADS)

    Choi, Yong Hyun; Min, Junhong; Cho, Sungbo

    2015-06-01

    Analysis on the interaction between proteins and cells is required for understanding the cellular behaviour and response. In this article, we characterized the adhesion and growth of 293/GFP cells on fetal bovine serum (FBS) coated indium tin oxide (ITO) electrode. Using optical and electrochemical measurement, it was able to detect the adsorption of the protein on the surface of the ITO electrode dependent on the concentration of the protein in the immersing solution or the immersing time. An increase in the amount of the adsorbed serum protein resulted in a decrease in anodic peak current and an increase in the charge transfer resistance extracted from the equivalent circuit fitting analysis. More cells adhered and proliferated on the ITO electrode which was pre-immersed in FBS medium rather than bare electrode. The effect of the FBS on cell behaviors was reflected in the impedance monitoring of cells at 21.5 kHz.

  17. Electrochemical recovery and isotope separation of lithium ion employing lithium ion conductive perovskite-type oxides

    Microsoft Academic Search

    Shunsuke Kunugi; Yoshiyuki Inaguma; Mitsuru Itoh

    1999-01-01

    The recovery of lithium ions by electrolysis using lithium ion conductive perovskite-type oxides La2\\/3?xLi3x?1\\/3?2xTiO3, as a separator, has been carried out. It was confirmed that La2\\/3?xLi3x?1\\/3?2xTiO3 has the selective permeability for lithium ions, and La2\\/3?xLi3x?1\\/3?2xTiO3 can be applied to the electrochemical recovery for lithium ions. Moreover, 6Li ion was recovered in preference to 7Li ion by this electrolysis. This indicates

  18. Enhanced electrochemical oxidation of Acid Red 3R wastewater with iron phosphomolybdate supported catalyst.

    PubMed

    Wang, Li; Yue, Lin; Shi, Feng; Guo, Jianbo; Yang, Jingliang; Lian, Jing; Luo, Xiao; Guo, Yankai

    2015-01-01

    Electrochemical oxidation of Acid Red 3R (AR3R) was investigated with the new catalyst of iron phosphomolybdate (FePMo12) supported on modified molecular sieves type 4 Å (4A) as packing materials in the reactor. The results of the Fourier transform infrared spectroscopy and X-ray diffraction indicated that the heteropolyanion had a Keggin structure. The optimal conditions for decolorization of simulated AR3R wastewater were as follows: current density 35 mA/cm(2), initial pH 4.0, airflow 0.08 m(3)/hour and inter-electrode distance 3.0 cm. With the addition of NaCl to the system, the decolorization efficiency increased. But Na2SO4 had a negative effect on the decolorization efficiency, which was attributed to the negative salt effect. The degradation mechanisms of AR3R were also discussed in detail. PMID:25812093

  19. Spinel manganese-nickel-cobalt ternary oxide nanowire array for high-performance electrochemical capacitor applications.

    PubMed

    Li, Lu; Zhang, Yongqi; Shi, Fan; Zhang, Yijun; Zhang, Jiaheng; Gu, Changdong; Wang, Xiuli; Tu, Jiangping

    2014-10-22

    Aligned spinel Mn-Ni-Co ternary oxide (MNCO) nanowires are synthesized by a facile hydrothermal method. As an electrode of supercapacitors, the MNCO nanowire array on nickel foam shows an outstanding specific capacitance of 638 F g(-1) at 1 A g(-1) and excellent cycling stability. This exceptional performance benefits from its nanowire architecture, which can provide large reaction surface area, fast ion and electron transfer, and good structural stability. Furthermore, an asymmetric supercapacitor (ASC) with high energy density is assembled successfully by employing the MNCO nanowire array as positive electrode and carbon black as negative electrode. The excellent electrochemical performances indicate the promising potential application of the ASC device in the energy storage field. PMID:25247606

  20. ?-Fe2O3 nanotubes-reduced graphene oxide composites as synergistic electrochemical capacitor materials.

    PubMed

    Lee, K K; Deng, S; Fan, H M; Mhaisalkar, S; Tan, H R; Tok, E S; Loh, K P; Chin, W S; Sow, C H

    2012-04-28

    We present a facile approach for the fabrication of a nanocomposite comprising ?-Fe(2)O(3) nanotubes (NTs) anchored on reduced graphene oxide (rGO) for electrochemical capacitors (ECs). The hollow tubular structure of the ?-Fe(2)O(3) NTs presents a high surface area for reaction, while the incorporation of rGO provides an efficient two-dimensional conductive pathway to allow fast, reversible redox reaction. As a result, the nanocomposite materials exhibit a specific capacitance which is remarkably higher (~7 times) than ?-Fe(2)O(3) NTs alone. In addition, the nanocomposites show excellent cycling life and large negative potential window. These findings suggest that such nanocomposites are a promising candidate as negative electrodes in asymmetrical capacitors with neutral electrolytes. PMID:22441701

  1. In-situ quantification of solid oxide fuel cell electrode microstructure by electrochemical impedance spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Yanxiang; Chen, Yu; Chen, Fanglin

    2015-03-01

    Three-dimensional (3D) microstructure of solid oxide fuel cell electrodes plays critical roles in determining fuel cell performance. The state-of-the-art quantification technique such as X-ray computed tomography enables direct calculation of geometric factors by 3D microstructure reconstruction. Taking advantages of in-situ, fast-responding and low cost, electrochemical impedance spectroscopy represented by distribution of relaxation time (DRT) is a novel technique to estimate geometric properties of fuel cell electrodes. In this study, we employed the anode supported cells with the cell configuration of Ni-YSZ || YSZ || LSM-YSZ as an example and compared the tortuosity factor of pores of the anode substrate layer by X-ray computed tomography and DRT analysis. Good agreement was found, validating the feasibility of in-situ microstructural quantification by using the DRT technique.

  2. Solid oxide electrolysis cell analysis by means of electrochemical impedance spectroscopy: A review

    NASA Astrophysics Data System (ADS)

    Nechache, A.; Cassir, M.; Ringuedé, A.

    2014-07-01

    High temperature water electrolysis based on Solid Oxide Electrolysis Cell (SOEC) is a very promising solution to produce directly pure hydrogen. However, degradation issues occurring during operation still represent a scientific and technological barrier in view of its development at an industrial scale. Electrochemical Impedance Spectroscopy (EIS) is a powerful in-situ fundamental tool adapted to the study of SOEC systems. Hence, after a quick presentation of EIS principle and data analysis methods, this review demonstrates how EIS can be used: (i) to characterize the performance and mechanisms of SOEC electrodes; (ii) as a complementary tool to study SOEC degradation processes for different cell configurations, in addition to post-test tools such as scanning electron microscopy (SEM) or X-ray diffraction (XRD). The use of EIS to establish a systematic SOEC analysis is introduced as well.

  3. Electrochemical Li insertion in lamellar (birnessite) and tunnel manganese oxides (todorokite)

    SciTech Connect

    Duncan, M.J.; Leroux, F.; Nazar, L.F.

    1998-07-01

    A comparison of Li insertion in manganese oxide phases with a tunnel (todorokite) framework, its two-dimensional layered precursor (birnessite/buserite), and Li-exchanged materials are presented. The results outline the effect of the MnO{sub 6} octahedral arrangement and framework composition on the electrochemical response. The interlayer cations in the lamellar materials are exchangeable for Li, giving rise to a lithiated birnessite that displays a sustainable capacity of 125 mAh/g. For todorokite, molten salt exchange using LiNO{sub 3} results in displacement of water from the tunnels, and incorporation of additional Li into the structure. Some of this Li is extractable during charge, resulting in a reversible capacity of 172 mAh/g in the voltage window 4.2--2.0V.

  4. Advanced launch system. Advanced development oxidizer turbopump program

    NASA Technical Reports Server (NTRS)

    1993-01-01

    On May 19, 1989, Pratt & Whitney was awarded contract NAS8-37595 by the National Aeronautics and Space Administration, Marshall Space Flight Center, Huntsville Alabama for an Advanced Development Program (ADP) to design, develop and demonstrate a highly reliable low cost, liquid oxygen turbopump for the Advanced Launch System (ALS). The ALS had an overall goal of reducing the cost of placing payloads in orbit by an order of magnitude. This goal would require a substantial reduction in life cycle costs, with emphasis on recurring costs, compared to current launch vehicles. Engine studies supporting these efforts were made for the Space Transportation Main Engine (STME). The emphasis on low cost required design simplification of components and subsystems such that the ground maintenance and test operations was minimized. The results of the Oxygen Turbopump ADP technology effort would provide data to be used in the STME. Initially the STME baseline was a gas generator cycle engine with a vacuum thrust level of 580,000 lbf. This was later increased to 650,000 lbf and the oxygen turbopump design approach was changed to reflect the new thrust level. It was intended that this ADP program be conducted in two phases. Phase 1, a basic phase, would encompass the preliminary design effort, and Phase II, an optional contract phase to cover design, fabrication and test evaluation of an oxygen turbopump at a component test facility at the NASA John C. Stennis Space Center in Mississippi. The basic phase included preliminary design and analysis, evaluation of low cost concepts, and evaluation of fabrication techniques. The option phase included design of the pump and support hardware, analysis of the final configuration to ensure design integrity, fabrication of hardware to demonstrate low cost, DVS Testing of hardware to verify the design, assembly of the turbopump and full scale turbopump testing. In December 1990, the intent of this ADP to support the design and development was changed. The design effort for the oxygen turbopump became part of the STME Phase B contract. The status of the pump design funded through this ADP was presented at the Preliminary Design Review (PDR) at the MSFC on October 24, 1990. Advancements in the design of the pump were subsequently continued under the Phase B Contract. The emphasis of this ADP became the demonstration of individual technologies that would have the greatest potential for reducing the recurring cost and increasing reliability. In October of 1992, overall program funding was reduced and work on this ADP was terminated.

  5. 3D CFD ELECTROCHEMICAL AND HEAT TRANSFER MODEL OF AN INTERNALLY MANIFOLDED SOLID OXIDE ELECTROLYSIS CELL

    SciTech Connect

    Grant L. Hawkes; James E. O'Brien; Greg Tao

    2011-11-01

    A three-dimensional computational fluid dynamics (CFD) electrochemical model has been created to model high-temperature electrolysis cell performance and steam electrolysis in an internally manifolded planar solid oxide electrolysis cell (SOEC) stack. This design is being evaluated at the Idaho National Laboratory for hydrogen production from nuclear power and process heat. Mass, momentum, energy, and species conservation and transport are provided via the core features of the commercial CFD code FLUENT. A solid-oxide fuel cell (SOFC) model adds the electrochemical reactions and loss mechanisms and computation of the electric field throughout the cell. The FLUENT SOFC user-defined subroutine was modified for this work to allow for operation in the SOEC mode. Model results provide detailed profiles of temperature, operating potential, steam-electrode gas composition, oxygen-electrode gas composition, current density and hydrogen production over a range of stack operating conditions. Single-cell and five-cell results will be presented. Flow distribution through both models is discussed. Flow enters from the bottom, distributes through the inlet plenum, flows across the cells, gathers in the outlet plenum and flows downward making an upside-down ''U'' shaped flow pattern. Flow and concentration variations exist downstream of the inlet holes. Predicted mean outlet hydrogen and steam concentrations vary linearly with current density, as expected. Effects of variations in operating temperature, gas flow rate, oxygen-electrode and steam-electrode current density, and contact resistance from the base case are presented. Contour plots of local electrolyte temperature, current density, and Nernst potential indicate the effects of heat transfer, reaction cooling/heating, and change in local gas composition. Results are discussed for using this design in the electrolysis mode. Discussion of thermal neutral voltage, enthalpy of reaction, hydrogen production, cell thermal efficiency, cell electrical efficiency, and Gibbs free energy are discussed and reported herein.

  6. Boron-doped cadmium oxide composite structures and their electrochemical measurements

    SciTech Connect

    Lokhande, B.J., E-mail: bjlokhande@yahoo.com [Lab of Smart Mtrls Supercapacitive and Energy Studies, School of Physical Sciences, Solapur University, Solapur 413255, Maharashtra (India); Ambare, R.C. [Lab of Smart Mtrls Supercapacitive and Energy Studies, School of Physical Sciences, Solapur University, Solapur 413255, Maharashtra (India); Mane, R.S. [School of Physical Sciences, Swami Ramanand Teerth Marathwada University, Nanded 431606 (India); Bharadwaj, S.R. [Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

    2013-08-01

    Graphical abstract: Conducting nano-fibrous 3% boron doped cadmium oxide thin films were prepared by SILAR and its super capacitive properties were studied. - Highlights: • Samples are of nanofibrous nature. • All samples shows pseudocapacitive behavior. • 3% B doped CdO shows good specific capacitance. • 3% B doped CdO shows maximum 74.93% efficiency at 14 mA/cm{sup 2}. • 3% B doped CdO shows 0.8 ? internal resistance. - Abstract: Boron-doped and undoped cadmium oxide composite nanostructures in thin film form were prepared onto stainless steel substrates by a successive ionic layer adsorption and reaction method using aqueous solutions of cadmium nitrate, boric acid and 1% H{sub 2}O{sub 2}. As-deposited films were annealed at 623 K for 1 h. The X-ray diffraction study shows crystalline behavior for both doped and undoped films with a porous topography and nano-wires type architecture, as observed in SEM image. Wettability test confirms the hydrophilic surface with 58° contact angle value. Estimated band gap energy is around 1.9 eV. Electrochemical behavior of the deposited films is attempted in 1 M KOH electrolyte using cyclic voltammetry (CV), electrochemical impedance spectroscopy and galvanostatic charge–discharge tests. Maximum values of the specific capacitance, specific energy and specific power obtained for 3% B doped CdO film at 2 mV/s scan rate are 20.05 F/g, 1.22 Wh/kg and 3.25 kW/kg, respectively.

  7. Joining of Oxide Dispersion Strengthened Steels for Advanced Reactors

    NASA Astrophysics Data System (ADS)

    Baker, B. W.; Brewer, L. N.

    2014-12-01

    The design, manufacture, and experimental analysis of structural materials capable of operation in the high temperatures, corrosive environments, and radiation damage spectra of future reactor designs remain one of the key pacing items for advanced reactor designs. The most promising candidate structural materials are vanadium-based refractory alloys, silicon carbide composites and oxide dispersion strengthened steels. Of these, oxide dispersion strengthened steels are a likely near-term candidate to meet required demands. This paper reviews different variants of oxide dispersion strengthened steels and discusses their capability with regard to high-temperature strength, corrosion resistance, and radiation damage resistance. Additionally, joining of oxide dispersion strengthened steels, which has been cited as a limiting factor preventing their use, is addressed and reviewed. Specifically, friction stir welding of these steels is reviewed as a promising joining method for oxide dispersion strengthened steels.

  8. Electrochemical Partial Oxidation of Methane in Solid Oxide Fuel Cells: Effect of Anode Reforming Activity

    Microsoft Academic Search

    Manoj R. Pillai; David M. Bierschenk; Scott A. Barnett

    2008-01-01

    Direct-methane solid oxide fuel cells were used to produce electricity and syngas. During initial operation at 750 °C, the\\u000a cells produced 0.9 W\\/cm2 and ?90% methane conversion to syngas at a rate of 30 sccm\\/cm2. However, the methane conversion decreased continuously over the first 30–40 h of operation, even though the solid oxide\\u000a fuel cells (SOFC) electrical performance was stable. An additional catalyst layer

  9. Electrochemical capacitance of iron oxide nanotube (Fe-NT): effect of annealing atmospheres.

    PubMed

    Sarma, Biplab; Jurovitzki, Abraham L; Ray, Rupashree S; Smith, York R; Mohanty, Swomitra K; Misra, Mano

    2015-07-01

    The effect of annealing atmosphere on the supercapacitance behavior of iron oxide nanotube (Fe-NT) electrodes has been explored and reported here. Iron oxide nanotubes were synthesized on a pure iron substrate through an electrochemical anodization process in an ethylene glycol solution containing 3% H2O and 0.5 wt.% NH4F. Subsequently, the annealing of the nanotubes was carried out at 500 °C for 2 h in various gas atmospheres such as air, oxygen (O2), nitrogen (N2), and argon (Ar). The morphology and crystal phases evolved after the annealing processes were examined via field emission scanning electron microscopy, x-ray diffraction, Raman spectroscopy, and x-ray photoelectron spectroscopy. The electrochemical capacitance properties of the annealed Fe-NT electrodes were evaluated by conducting cyclic voltammetry (CV), galvanostatic charge-discharge, and electrochemical impedance spectroscopy tests in the Li2SO4 electrolyte. Based on these experiments, it was found that the capacitance of the Fe-NT electrodes annealed in air and O2 atmospheres shows mixed behavior comprising both the electric double layer and pseudocapacitance. However, annealing in N2 and Ar environments resulted in well-defined redox peaks in the CV profiles of the Fe-NT electrodes, which are therefore attributed to the relatively higher pseudonature of the capacitance in these electrodes. Based on the galvanostatic charge-discharge studies, the specific capacitance achieved in the Fe-NT electrode after annealing in Ar was about 300 mF cm(-2), which was about twice the value obtained for N2-annealed Fe-NTs and three times higher than those annealed in air and O2. The experiments also demonstrated excellent cycle stability for the Fe-NT electrodes with 83%-85% capacitance retention, even after many charge-discharge cycles, irrespective of the gas atmospheres used during annealing. The increase in the specific capacitance was discussed in terms of increased oxygen vacancies as a result of the enhanced transformation of the hematite (?-Fe2O3) phase to the magnetite (Fe3O4) phase for the electrodes annealed in the N2 and Ar atmospheres. PMID:26057179

  10. Electrochemical capacitance of iron oxide nanotube (Fe-NT): effect of annealing atmospheres

    NASA Astrophysics Data System (ADS)

    Sarma, Biplab; Jurovitzki, Abraham L.; Ray, Rupashree S.; Smith, York R.; Mohanty, Swomitra K.; Misra, Mano

    2015-07-01

    The effect of annealing atmosphere on the supercapacitance behavior of iron oxide nanotube (Fe-NT) electrodes has been explored and reported here. Iron oxide nanotubes were synthesized on a pure iron substrate through an electrochemical anodization process in an ethylene glycol solution containing 3% H2O and 0.5 wt.% NH4F. Subsequently, the annealing of the nanotubes was carried out at 500 °C for 2 h in various gas atmospheres such as air, oxygen (O2), nitrogen (N2), and argon (Ar). The morphology and crystal phases evolved after the annealing processes were examined via field emission scanning electron microscopy, x-ray diffraction, Raman spectroscopy, and x-ray photoelectron spectroscopy. The electrochemical capacitance properties of the annealed Fe-NT electrodes were evaluated by conducting cyclic voltammetry (CV), galvanostatic charge–discharge, and electrochemical impedance spectroscopy tests in the Li2SO4 electrolyte. Based on these experiments, it was found that the capacitance of the Fe-NT electrodes annealed in air and O2 atmospheres shows mixed behavior comprising both the electric double layer and pseudocapacitance. However, annealing in N2 and Ar environments resulted in well-defined redox peaks in the CV profiles of the Fe-NT electrodes, which are therefore attributed to the relatively higher pseudonature of the capacitance in these electrodes. Based on the galvanostatic charge–discharge studies, the specific capacitance achieved in the Fe-NT electrode after annealing in Ar was about 300 mF cm?2, which was about twice the value obtained for N2-annealed Fe-NTs and three times higher than those annealed in air and O2. The experiments also demonstrated excellent cycle stability for the Fe-NT electrodes with 83%–85% capacitance retention, even after many charge–discharge cycles, irrespective of the gas atmospheres used during annealing. The increase in the specific capacitance was discussed in terms of increased oxygen vacancies as a result of the enhanced transformation of the hematite (?-Fe2O3) phase to the magnetite (Fe3O4) phase for the electrodes annealed in the N2 and Ar atmospheres.

  11. Oxidative Lipidomics Coming of Age: Advances in Analysis of Oxidized Phospholipids in Physiology and Pathology

    PubMed Central

    Pitt, Andrew R.

    2015-01-01

    Abstract Significance: Oxidized phospholipids are now well recognized as markers of biological oxidative stress and bioactive molecules with both pro-inflammatory and anti-inflammatory effects. While analytical methods continue to be developed for studies of generic lipid oxidation, mass spectrometry (MS) has underpinned the advances in knowledge of specific oxidized phospholipids by allowing their identification and characterization, and it is responsible for the expansion of oxidative lipidomics. Recent Advances: Studies of oxidized phospholipids in biological samples, from both animal models and clinical samples, have been facilitated by the recent improvements in MS, especially targeted routines that depend on the fragmentation pattern of the parent molecular ion and improved resolution and mass accuracy. MS can be used to identify selectively individual compounds or groups of compounds with common features, which greatly improves the sensitivity and specificity of detection. Application of these methods has enabled important advances in understanding the mechanisms of inflammatory diseases such as atherosclerosis, steatohepatitis, leprosy, and cystic fibrosis, and it offers potential for developing biomarkers of molecular aspects of the diseases. Critical Issues and Future Directions: The future in this field will depend on development of improved MS technologies, such as ion mobility, novel enrichment methods and databases, and software for data analysis, owing to the very large amount of data generated in these experiments. Imaging of oxidized phospholipids in tissue MS is an additional exciting direction emerging that can be expected to advance understanding of physiology and disease. Antioxid. Redox Signal. 22, 1646–1666. PMID:25694038

  12. Electrochemical oxidation of nitrite and the oxidation and reduction of NO2 in the room temperature ionic liquid [C2mim][NTf2].

    PubMed

    Broder, Tessa L; Silvester, Debbie S; Aldous, Leigh; Hardacre, Christopher; Compton, Richard G

    2007-07-12

    The electrochemical oxidation of potassium nitrite has been studied in the room temperature ionic liquid (RTIL) [C2mim][NTf2] by cyclic voltammetry at platinum electrodes. A chemically irreversible oxidation peak was observed, and a solubility of 7.5(+/-0.5) mM and diffusion coefficient of 2.0(+/-0.2)x10(-11) m2 s(-1) were calculated from potential step chronoamperometry on the microdisk electrode. A second, and sometimes third, oxidation peak was also observed when the anodic limit was extended, and these were provisionally assigned to the oxidation of nitrogen dioxide (NO2) and nitrate (NO3-), respectively. The electrochemical oxidation of nitrogen dioxide gas (NO2) was also studied by cyclic voltammetry in [C2mim][NTf2] on Pt electrodes of various size, giving a solubility of ca. 51(+/-0.2) mM and diffusion coefficient of 1.6(+/-0.05)x10(-10) m2 s(-1) (at 25 degrees C). It is likely that NO2 exists predominantly as its dimer, N2O4, at room temperature. The oxidation mechanism follows a CE process, which involves the initial dissociation of the dimer to the monomer, followed by a one-electron oxidation. A second, larger oxidation peak was observed at more positive potentials and is thought to be the direct oxidation of N2O4. In addition to understanding the mechanisms of NO2- and NO2 oxidations, this work has implications in the electrochemical detection of nitrite ions and of NO2 gas in RTIL media, the latter which may be of particular use in gas sensing. PMID:17571880

  13. Fe3O4 magnetic nanoparticles/reduced graphene oxide nanosheets as a novel electrochemical and bioeletrochemical sensing platform.

    PubMed

    Teymourian, Hazhir; Salimi, Abdollah; Khezrian, Somayeh

    2013-11-15

    We have developed Fe3O4 magnetic nanoparticles/reduced graphene oxide nanosheets modified glassy carbon (Fe3O4/r-GO/GC) electrode as a novel system for the preparation of electrochemical sensing platform. Decorating Fe3O4 nanoparticles on graphene sheets was performed via a facile one-step chemical reaction strategy, where the reduction of GO and the in-situ generation of Fe3O4 nanoparticles occurred simultaneously. Characterization of as-made nanocomposite using X-ray diffraction (XRD), transmission electron microscopy (TEM) and alternative gradient force magnetometry (AGFM) clearly demonstrate the successful attachment of monodisperse Fe3O4 nanoparticles to graphene sheets. Electrochemical studies revealed that the Fe3O4/r-GO/GC electrode possess excellent electrocatalytic activities toward the low potential oxidation of NADH (0.05 V vs. Ag/AgCl) as well as the catalytic reduction of O2 and H2O2 at reduced overpotentials. Via immobilization of lactate dehydrogenase (LDH) as a model dehydrogenase enzyme onto the Fe3O4/r-GO/GC electrode surface, the ability of modified electrode for biosensing lactate was demonstrated. In addition, using differential pulse voltammetry (DPV) to investigate the electrochemical oxidation behavior of ascorbic acid (AA), dopamine (DA) and uric acid (UA) at Fe3O4/r-GO/GC electrode, the high electrocatalytic activity of the modified electrode toward simultaneous detection of these compounds was indicated. Finally, based on the strong electrocatalytic action of Fe3O4/r-GO/GC electrode toward both oxidation and reduction of nitrite, a sensitive amperometric sensor for nitrite determination was proposed. The Fe3O4/r-GO hybrid presented here showing favorable electrochemical features may hold great promise to the development of electrochemical sensors, molecular bioelectronic devices, biosensors and biofuel cells. PMID:23708810

  14. Determination of ammonia based on the electrochemical oxidation of N,N'-diphenyl-1,4-phenylenediamine in propylene carbonate.

    PubMed

    Ji, Xiaobo; Compton, Richard G

    2007-11-01

    The oxidation of N,N'-diphenyl-1,4-phenylenediamine (DPPD) has been studied by cyclic voltammetry at glassy carbon electrodes in propylene carbonate. Next, the reaction between ammonia and DPPD was similarly investigated. It has been shown that ammonia reversibly removes protons from oxidized DPPD molecules, thus facilitating the oxidative process with the emergence of a new wave at less positive potentials. The results suggest a novel methodology for the electrochemical determination of ammonia based on its interaction with DPPD in propylene carbonate. The measurement of the current of the new wave is shown to scale linearly with the ammonia concentration up to ca. 200 ppm and above. PMID:17998752

  15. Synthesis of Pt nanoparticles on electrochemically reduced graphene oxide by potentiostatic and alternate current methods

    SciTech Connect

    Molina, J.; Fernández, J.; Río, A.I. del; Bonastre, J.; Cases, F., E-mail: fjcases@txp.upv.es

    2014-03-01

    Reduced graphene oxide (RGO) has been synthesized on Pt wires by means of a potentiodynamic method between + 0.6 V and ? 1.4 V for 20 scans. Cyclic voltammetry characterization of the coatings showed the typical capacitative behavior of graphene. Pt nanoparticles were synthesized on Pt–RGO electrodes by means of potentiostatic methods and a comparison between different synthesis potentials (? 0.16, 0, + 0.2 and + 0.4 V) for the same synthesis charge (mC·cm{sup ?2}) was established. The electrodes obtained were characterized in 0.5 M H{sub 2}SO{sub 4} solution to observe the characteristic oxidation and reduction processes of the Pt surface. A 0.5 M H{sub 2}SO{sub 4}/0.5 M CH{sub 3}OH solution was used to measure the catalytic properties of the deposits against methanol oxidation. The most appropriate potential to perform the synthesis was 0 V followed by ? 0.16 V and + 0.2 V. The morphology of the coatings varied depending on the potential applied as observed by scanning electron microscopy. Alternate current methods were also used to synthesize Pt nanoparticles and compare the results with the traditional potentiostatic method. Different frequencies were used: 0.1, 1, 10, 100, 1000 and 10 000 Hz. Alternate current synthesis is more efficient than traditional potentiostatic methods, obtaining more electroactive coatings with less effective synthesis time. - Highlights: • Reduced graphene oxide has been obtained by electrochemical reduction on Pt wires. • Pt nanoparticles have been obtained potentiostatically at different potentials. • Pt nanoparticles have been obtained by ac methods with different frequencies. • ac synthesis is a better synthesis method than potentiostatic synthesis.

  16. High-rate electrochemical partial oxidation of methane in solid oxide fuel cells

    Microsoft Academic Search

    Zhongliang Zhan; Yuanbo Lin; Manoj Pillai; Ilwon Kim; Scott A. Barnett

    2006-01-01

    This paper describes results on direct-methane solid oxide fuel cell (air, LSM-YSZ|YSZ|Ni-YSZ, CH4) operation for combined electricity and syngas production. Thermodynamic equilibrium predictions showed that efficient methane conversion to syngas is expected for SOFC operating temperature >700°C and O2?\\/CH4 ratios of ?1. A simple thermal analysis was used to determine conditions where the cell produces enough heat to self-sustain its

  17. Electrochemical Urea Biosensor Based on Sol-gel Derived Nanostructured Cerium Oxide

    NASA Astrophysics Data System (ADS)

    Ansari, Anees A.; Azahar, Md; Malhotra, B. D.

    2012-04-01

    Urease (Urs) and glutamate dehydrogenase (GLDH) have been co-immobilized onto a nanostructured-cerium oxide (Nano-CeO2) film deposited onto a indium-tin-oxide (ITO) coated glass substrate by dip-coating via sol-gel process for urea detection. This nanostructured film has characterized using X-ray diffraction (XRD), Fourier transform infrared (FTIR), Scanning electron microscope (SEM) and electrochemical techniques, respectively. The particle size of the Nano-CeO2 film has been found to be 23 nm. Electrochemcial response (CV) studies show that Ur-GLDH/Nano-CeO2/ITO bioelectrode is found to be sensitive in the 10-80 mg/dL urea concentration range and can detect urea concentration upto 0.1 mg/dL level. The value of Michaelis-Menten constant (Km) estimated using Lineweaver-Burke plot found as 6.09 mg/dL indicates enhancement in the affinity and/or activity of enzyme attached to their nanobiocomposite. This bioelectrode retained 95% of enzyme activity after 6 months at 4°C.

  18. THERMAL AND ELECTROCHEMICAL THREE DIMENSIONAL CFD MODEL OF A PLANAR SOLID OXIDE ELECTROLYSIS CELL

    SciTech Connect

    Grant Hawkes; Jim O'Brien; Carl Stoots; Steve Herring; Mehrdad Shahnam

    2005-07-01

    A three-dimensional computational fluid dynamics (CFD) model has been created to model high-temperature steam electrolysis in a planar solid oxide electrolysis cell (SOEC). The model represents a single cell, as it would exist in an electrolysis stack. Details of the model geometry are specific to a stack that was fabricated by Ceramatec , Inc. and tested at the Idaho National Laboratory. Mass, momentum, energy, and species conservation and transport are provided via the core features of the commercial CFD code FLUENT2. A solid-oxide fuel cell (SOFC) model adds the electrochemical reactions and loss mechanisms and computation of the electric field throughout the cell. The FLUENT SOFC user-defined subroutine was modified for this work to allow for operation in the SOEC mode. Model results provide detailed profiles of temperature, Nernst potential, operating potential, anode-side gas composition, cathode-side gas composition, current density and hydrogen production over a range of stack operating conditions. Mean model results are shown to compare favorably with experimental results obtained from an actual ten-cell stack tested at INL.

  19. Electrochemical Characteristics of Tin Oxide-Graphite as Anode Material for Lithium-ion Cells

    NASA Astrophysics Data System (ADS)

    Hasanaly, Siti Munirah

    2010-03-01

    Tin oxide anode materials used in lithium-ion cells experience large volume changes during charging and discharging which cause substantial losses in capacity. In this work, the tin oxide-graphite composite is proposed as an alternative anode material to overcome this problem. The composite was synthesised from a solution of tin chloride dihydrate and graphite powders with citric acid as the chelating agent. In this sol-gel method, a solid phase is formed through a chemical reaction in a liquid phase at moderate temperature. The technique offers several advantages compared to the solid state synthesis technique such as the ability to maintain the homogeneous mixture of precursors during synthesis and to produce small particles. The electrochemical behaviour of the anode material was investigated by means of galvanostatic charge discharge technique. An initial reversible capacity of 748 mAh/g is obtained and nearly 600 mAh/g was retained upon the reaching the fifth cycle. This study shows that the presence of graphite is able to minimise the agglomeration of tin particles that causes large volume changes during cycling, thereby improving cyclability of the anode material.

  20. Morphological and substrate effects on the electrochemical behaviour of doped tin oxide anodes

    NASA Astrophysics Data System (ADS)

    Miljkovic, Bojan

    Films of Sb-doped SnO2 were successfully fabricated on a Ti substrate through precursor application by spin coating followed by a thermal decomposition process. The dependence of film characteristics on fabrication temperature was studied in the range of 500 to 800°C. An optimum electrocatalytic response was found for a firing temperature of 600°C. This was attributed to a balance between Sb-doping effects, titanium substrate oxidation, and film morphological development. This was determined through observation of the morphology, crystallographic texture, and electrochemical characteristics, such as the oxygen evolution potential (OEP), ferri/ferrocyanide electron transfer reaction, and phenol oxidation. Polymerization of phenol and the subsequent deactivation of the anode surface was related to the active surface area of the SnO2 film. Preliminary studies on the effect of Ni-Sb and Zn-Sb co-doping of SnO2 were conducted. The addition of Ni was shown to decrease the film conductivity while maintaining the OEP. Inclusion of Zn resulted in the formation of a second phase, Zn2SnO4 , which effectively inhibited oxygen evolution causing an increase in the OEP.

  1. X-ray absorption spectroscopy studies of electrochemically deposited thin oxide films

    SciTech Connect

    Balasubramanian, M.; Melendres, C.A. [Argonne National Lab., IL (United States); Mansour, A.N. [Naval Surface Warfare Center, West Bethesda, MD (United States); Mini, S. [Northern Illinois Univ., DeKalb, IL (United States)

    1998-12-31

    Radioactive contamination of piping systems and storage tanks generally emanates from radionuclides that have been incorporated into corrosion products and scale deposits that coat the surface of the metal alloys which constitute the materials of construction of the pipes and tanks. Knowledge of both the local structure of the corrosion scales by itself and that of the heavy metal ions that are incorporated into the corrosion scales is essential in developing cost-effective clean-up processes via chemical and electrochemical methods. The authors have utilized in situ X-ray Absorption Fine Structure Spectroscopy to investigate the structure and composition of thin oxide films of nickel and iron that have been prepared by electrodeposition on a graphite substrate from aqueous solutions. The films are generally disordered. Structural information has been obtained form the analysis of the data. They also present initial findings on the local structure of heavy metal ions, e.g. Sr and Ce, incorporated into the electrodeposited nickel oxide films. Their results are of importance in a number of technological applications, among them, batteries, fuel cells, electrochromic and ferroelectric materials, corrosion protection, as well as environmental speciation and remediation.

  2. Electrochemical and microstructural studies of tantalum and its oxide films for biomedical applications in endovascular surgery.

    PubMed

    Silva, R A; Walls, M; Rondot, B; Da Cunha Belo, M; Guidoin, R

    2002-05-01

    The most popular coronary stents are made of 316L stainless steel and self-expandable Nitinol. Nevertheless, Ta has already been used to make stents for endovascular surgery and may constitute a good alternative to the other materials because of its higher corrosion resistance and radio-opacity property, which may facilitate the follow-up of stent catheterization. The characterization of Ta and its natural passive oxide films has been performed in a 0.15 M NaCl solution (simulated body fluid - SBF) using anodic polarizations, electrochemical impedance spectroscopy and photoelectrochemical techniques. Changes in microstructure have been observed by atomic force microscopy (AFM). Polarization curves show the existence of a current density increase between 1.40 and 1.80 V. Bode complex plots show that some perturbation of the film occurred in this potential interval which may be associated with a decrease in polarization resistance, Rp, indicating that the film may be less resistant to corrosive attack. Mott-Schottky capacity measurements show that the density of donors, Nd, varies with polarization. The optical band gap, E(g), which is equal to 4.1 eV did not show variations in our experiments. The localized formation on the electrode surface, in the above potential interval of a Ta compound (possibly an oxide-hydroxide) was observed by AFM, and this may explain the appearance of the current density peak and capacity behavior at those potentials. PMID:15348603

  3. Synthesis of gallium nitride nanostructures by nitridation of electrochemically deposited gallium oxide on silicon substrate.

    PubMed

    Ghazali, Norizzawati Mohd; Yasui, Kanji; Hashim, Abdul Manaf

    2014-01-01

    Gallium nitride (GaN) nanostructures were successfully synthesized by the nitridation of the electrochemically deposited gallium oxide (Ga2O3) through the utilization of a so-called ammoniating process. Ga2O3 nanostructures were firstly deposited on Si substrate by a simple two-terminal electrochemical technique at a constant current density of 0.15 A/cm(2) using a mixture of Ga2O3, HCl, NH4OH and H2O for 2 h. Then, the deposited Ga2O3 sample was ammoniated in a horizontal quartz tube single zone furnace at various ammoniating times and temperatures. The complete nitridation of Ga2O3 nanostructures at temperatures of 850°C and below was not observed even the ammoniating time was kept up to 45 min. After the ammoniating process at temperature of 900°C for 15 min, several prominent diffraction peaks correspond to hexagonal GaN (h-GaN) planes were detected, while no diffraction peak of Ga2O3 structure was detected, suggesting a complete transformation of Ga2O3 to GaN. Thus, temperature seems to be a key parameter in a nitridation process where the deoxidization rate of Ga2O3 to generate gaseous Ga2O increase with temperature. The growth mechanism for the transformation of Ga2O3 to GaN was proposed and discussed. It was found that a complete transformation can not be realized without a complete deoxidization of Ga2O3. A significant change of morphological structures takes place after a complete transformation of Ga2O3 to GaN where the original nanorod structures of Ga2O3 diminish, and a new nanowire-like GaN structures appear. These results show that the presented method seems to be promising in producing high-quality h-GaN nanostructures on Si. PMID:25593562

  4. Synthesis of gallium nitride nanostructures by nitridation of electrochemically deposited gallium oxide on silicon substrate

    NASA Astrophysics Data System (ADS)

    Ghazali, Norizzawati Mohd; Yasui, Kanji; Hashim, Abdul Manaf

    2014-12-01

    Gallium nitride (GaN) nanostructures were successfully synthesized by the nitridation of the electrochemically deposited gallium oxide (Ga2O3) through the utilization of a so-called ammoniating process. Ga2O3 nanostructures were firstly deposited on Si substrate by a simple two-terminal electrochemical technique at a constant current density of 0.15 A/cm2 using a mixture of Ga2O3, HCl, NH4OH and H2O for 2 h. Then, the deposited Ga2O3 sample was ammoniated in a horizontal quartz tube single zone furnace at various ammoniating times and temperatures. The complete nitridation of Ga2O3 nanostructures at temperatures of 850°C and below was not observed even the ammoniating time was kept up to 45 min. After the ammoniating process at temperature of 900°C for 15 min, several prominent diffraction peaks correspond to hexagonal GaN (h-GaN) planes were detected, while no diffraction peak of Ga2O3 structure was detected, suggesting a complete transformation of Ga2O3 to GaN. Thus, temperature seems to be a key parameter in a nitridation process where the deoxidization rate of Ga2O3 to generate gaseous Ga2O increase with temperature. The growth mechanism for the transformation of Ga2O3 to GaN was proposed and discussed. It was found that a complete transformation can not be realized without a complete deoxidization of Ga2O3. A significant change of morphological structures takes place after a complete transformation of Ga2O3 to GaN where the original nanorod structures of Ga2O3 diminish, and a new nanowire-like GaN structures appear. These results show that the presented method seems to be promising in producing high-quality h-GaN nanostructures on Si.

  5. Enriching distinctive microbial communities from marine sediments via an electrochemical-sulfide-oxidizing process on carbon electrodes.

    PubMed

    Li, Shiue-Lin; Nealson, Kenneth H

    2015-01-01

    Sulfide is a common product of marine anaerobic respiration, and a potent reactant biologically and geochemically. Here we demonstrate the impact on microbial communities with the removal of sulfide via electrochemical methods. The use of differential pulse voltammetry revealed that the oxidation of soluble sulfide was seen at +30 mV (vs. SHE) at all pH ranges tested (from pH = 4 to 8), while non-ionized sulfide, which dominated at pH = 4 was poorly oxidized via this process. Two mixed cultures (CAT and LA) were enriched from two different marine sediments (from Catalina Island, CAT; from the Port of Los Angeles, LA) in serum bottles using a seawater medium supplemented with lactate, sulfate, and yeast extract, to obtain abundant biomass. Both CAT and LA cultures were inoculated in electrochemical cells (using yeast-extract-free seawater medium as an electrolyte) equipped with carbon-felt electrodes. In both cases, when potentials of +630 or +130 mV (vs. SHE) were applied, currents were consistently higher at +630 then at +130 mV, indicating more sulfide being oxidized at the higher potential. In addition, higher organic-acid and sulfate conversion rates were found at +630 mV with CAT, while no significant differences were found with LA at different potentials. The results of microbial-community analyses revealed a decrease in diversity for both CAT and LA after electrochemical incubation. In addition, some bacteria (e.g., Clostridium and Arcobacter) not well-known to be capable of extracellular electron transfer, were found to be dominant in the electrochemical cells. Thus, even though the different mixed cultures have different tolerances for sulfide, electrochemical-sulfide removal can lead to major population changes. PMID:25741331

  6. Enriching distinctive microbial communities from marine sediments via an electrochemical-sulfide-oxidizing process on carbon electrodes

    PubMed Central

    Li, Shiue-Lin; Nealson, Kenneth H.

    2015-01-01

    Sulfide is a common product of marine anaerobic respiration, and a potent reactant biologically and geochemically. Here we demonstrate the impact on microbial communities with the removal of sulfide via electrochemical methods. The use of differential pulse voltammetry revealed that the oxidation of soluble sulfide was seen at +30 mV (vs. SHE) at all pH ranges tested (from pH = 4 to 8), while non-ionized sulfide, which dominated at pH = 4 was poorly oxidized via this process. Two mixed cultures (CAT and LA) were enriched from two different marine sediments (from Catalina Island, CAT; from the Port of Los Angeles, LA) in serum bottles using a seawater medium supplemented with lactate, sulfate, and yeast extract, to obtain abundant biomass. Both CAT and LA cultures were inoculated in electrochemical cells (using yeast-extract-free seawater medium as an electrolyte) equipped with carbon-felt electrodes. In both cases, when potentials of +630 or +130 mV (vs. SHE) were applied, currents were consistently higher at +630 then at +130 mV, indicating more sulfide being oxidized at the higher potential. In addition, higher organic-acid and sulfate conversion rates were found at +630 mV with CAT, while no significant differences were found with LA at different potentials. The results of microbial-community analyses revealed a decrease in diversity for both CAT and LA after electrochemical incubation. In addition, some bacteria (e.g., Clostridium and Arcobacter) not well-known to be capable of extracellular electron transfer, were found to be dominant in the electrochemical cells. Thus, even though the different mixed cultures have different tolerances for sulfide, electrochemical-sulfide removal can lead to major population changes. PMID:25741331

  7. Detection of the short-lived cation radical intermediate in the electrochemical oxidation of N,N-dimethylaniline by scanning electrochemical microscopy.

    PubMed

    Cao, Fahe; Kim, Jiyeon; Bard, Allen J

    2014-12-31

    The short-lived intermediate N,N-dimethylaniline (DMA) cation radical, DMA(•+), was detected during the oxidation of DMA in MeCN with 0.1 M tetra-n-butylammonium hexafluorophosphate. The detection was accomplished at steady state by scanning electrochemical microscopy (SECM) with ultramicroelectrodes using the tip generation/substrate collection mode. Cyclic voltammetry (CV) with a 2 mm Pt electrode indicates that DMA oxidation in acetonitrile is followed by a dimerization and two electrochemical reactions, which is consistent with previous results. The DMA(•+) intermediate is detected by SECM, where the DMA(•+) generated at the ca. 500 nm radius Pt tip is collected on a 5 ?m radius Pt substrate when the gap between the tip and the substrate is a few hundred nanometers. Almost all of the DMA(•+) is reduced at the substrate when the gap is 200 nm or less, yielding a dimerization rate constant of 2.5 × 10(8) M(-1)·s(-1) based on a simulation. This is roughly 3 orders of magnitude larger than the value estimated by fast-scan CV. We attribute this discrepancy to the effects of double-layer capacitance charging and adsorbed species in the high scan rate CV. PMID:25478724

  8. Sensitive electrochemical aptasensor for thrombin detection based on graphene served as platform and graphene oxide as enhancer.

    PubMed

    He, Chun; Xu, Zenghong; Sun, Tao; Wang, Li

    2014-01-01

    A sensitive electrochemical aptasensor was developed with conductive graphene served as platform and inert graphene oxide (GO) as enhancer. An electrodeposited nano-Au layer was firstly formed on conductive graphene modified glass carbon electrode surface for further immobilizing of electrochemical redox probe hexacyanoferrates nanoparticles (NiHCFNPs). Subsequently, another nano-Au layer was formed for immobilizing of thrombin aptamer (TBA). In the presence of thrombin, the TBA on the electrode surface could bind with thrombin, which made a barrier for electrons and inhibited the electro-transfer, resulting in the decreased electrochemical signals of NiHCFNPs. Owing to the non-conductivity property of graphene oxide, further decreased electrochemical signals of NiHCFNPs could be obtained via the sandwich reaction with GO-labeled TBA. According to the signal changes before the thrombin recognition and after sandwich reaction, trace detection of thrombin could be achieved. As a result, the proposed approach showed a high sensitivity and a wider linearity to thrombin in the range from 0.005 nM to 50 nM with a detection limit of 1 pM. PMID:24142359

  9. Degradation of pesticides in water using solar advanced oxidation processes

    Microsoft Academic Search

    Margarita Hincapié Pérez; Gustavo Peñuela; Manuel I. Maldonado; Octavio Malato; Pilar Fernández-Ibáñez; Isabel Oller; Wolfgang Gernjak; Sixto Malato

    2006-01-01

    Alachlor, atrazine and diuron dissolved in water at 50, 25 and 30mg\\/L, respectively were photodegraded by Fe2+\\/H2O2, Fe3+\\/H2O2, TiO2 and TiO2\\/Na2S2O8 treatments driven by solar energy at pilot-plant scale using a compound parabolic collector (CPC) photoreactor. All the advanced oxidation processes (AOPs) employed mainly compared the TOC mineralisation rate to evaluate treatment effectiveness. Parent compound disappearance, anion release and oxidant

  10. Bipolar plating of metal contacts onto oxide interconnection for solid oxide electrochemical cell

    DOEpatents

    Isenberg, A.O.

    1987-03-10

    Disclosed is a method of forming an adherent metal deposit on a conducting layer of a tube sealed at one end. The tube is immersed with the sealed end down into an aqueous solution containing ions of the metal to be deposited. An ionically conducting aqueous fluid is placed inside the tube and a direct current is passed from a cathode inside the tube to an anode outside the tube. Also disclosed is a multi-layered solid oxide fuel cell tube which consists of an inner porous ceramic support tube, a porous air electrode covering the support tube, a non-porous electrolyte covering a portion of the air electrode, a non-porous conducting interconnection covering the remaining portion of the electrode, and a metal deposit on the interconnection. 1 fig.

  11. Bipolar plating of metal contacts onto oxide interconnection for solid oxide electrochemical cell

    DOEpatents

    Isenberg, Arnold O. (Forest Hills Boro, PA)

    1987-01-01

    Disclosed is a method of forming an adherent metal deposit on a conducting layer of a tube sealed at one end. The tube is immersed with the sealed end down into an aqueous solution containing ions of the metal to be deposited. An ionically conducting aqueous fluid is placed inside the tube and a direct current is passed from a cathode inside the tube to an anode outside the tube. Also disclosed is a multi-layered solid oxide fuel cell tube which consists of an inner porous ceramic support tube, a porous air electrode covering the support tube, a non-porous electrolyte covering a portion of the air electrode, a non-porous conducting interconnection covering the remaining portion of the electrode, and a metal deposit on the interconnection.

  12. Oxide Reduction in Advanced Metal Stacks for Microelectronic Applications Wentao Qin, Alex A. Volinsky1

    E-print Network

    Volinsky, Alex A.

    Oxide Reduction in Advanced Metal Stacks for Microelectronic Applications Wentao Qin, Alex A used for microelectronic interconnect applications. Interfacial oxides can cause device performance degradation and failure by significantly increasing electrical resistance. Interfacial oxide layers found

  13. Development of Advanced Electrochemical Emission Spectroscopy for Monitoring Corrosion in Simulated DOE Liquid Waste

    SciTech Connect

    Digby Macdonald; Brian Marx; Balaji Soundararajan; Morgan Smith

    2005-07-28

    The different tasks that have been carried out under the current program are as follows: (1) Theoretical and experimental assessment of general corrosion of iron/steel in borate buffer solutions by using electrochemical impedance spectroscopy (EIS), ellipsometry and XPS techniques; (2) Development of a damage function analysis (DFA), which would help in predicting the accumulation of damage due to pitting corrosion in an environment prototypical of DOE liquid waste systems; (3) Experimental measurement of crack growth rate, acoustic emission signals, and coupling currents for fracture in carbon and low alloy steels as functions of mechanical (stress intensity), chemical (conductivity), electrochemical (corrosion potential, ECP), and microstructural (grain size, precipitate size, etc) variables in a systematic manner, with particular attention being focused on the structure of the noise in the current and its correlation with the acoustic emissions; (4) Development of fracture mechanisms for carbon and low alloy steels that are consistent with the crack growth rate, coupling current data and acoustic emissions; (5) Inserting advanced crack growth rate models for SCC into existing deterministic codes for predicting the evolution of corrosion damage in DOE liquid waste storage tanks; (6) Computer simulation of the anodic and cathodic activity on the surface of the steel samples in order to exactly predict the corrosion mechanisms; (7) Wavelet analysis of EC noise data from steel samples undergoing corrosion in an environment similar to that of the high level waste storage containers, to extract data pertaining to general, pitting and stress corrosion processes, from the overall data. The work has yielded a number of important findings, including an unequivocal demonstration of the role of chloride ion in passivity breakdown on nickel in terms of cation vacancy generation within the passive film, the first detection and characterization of individual micro fracture events in stress corrosion cracking, and the determination of kinetic parameters for the generation and annihilation of point defects in the passive film on iron. The existence of coupling between the internal crack environment and the external cathodic environment, as predicted by the coupled environment fracture model (CEFM), has also been indisputably established for the AISI 4340/NaOH system. It is evident from the studies that analysis of coupling current noise is a very sensitive tool for studying the crack tip processes in relation to the chemical, mechanical, electrochemical, and microstructural properties of the system. Experiments are currently being carried out to explore these crack tip processes by simultaneous measurement of the acoustic activity at the crack tip in an effort to validate the coupling current data. These latter data are now being used to deterministically predict the accumulation of general and localized corrosion damage on carbon in prototypical DOE liquid waste storage tanks. Computer simulation of the cathodic and anodic activity on the steel surfaces is also being carried out in an effort to simulate the actual corrosion process. Wavelet analysis of the coupling current data promises to be a useful tool to differentiate between the different corrosion mechanisms. Hence, wavelet analysis of the coupling current data from the DOE waste containers is also being carried out to extract data pertaining to general, pitting and stress corrosion processes, from the overall data which is bound to contain noise fluctuations due to any or all of the above mentioned processes.

  14. The electrochemical oxidation of cobalt tris(dithiocarbamates) and tris(diselenocarbamates) in acetonitrile; a combined spectroscopic and voltammetric study

    Microsoft Academic Search

    John A. Alden; Alan M. Bond; Ray Colton; Richard G. Compton; John C. Eklund; Yvonne A. Mah; Peter J. Mahon; Vanda Tedesco

    1998-01-01

    The electrochemical oxidation of cobalt(III) dithiocarbamates and diselenocarbamates (CoL3) in acetonitrile+0.1 M Bu4NPF6 is shown to occur via the mechanism: (E) CoL3?[CoL3]++e?; (C2) 2[CoL3]+?[Co2L5]++oxidized ligand; (C) [Co2L5]++2CH3CN?CoL3+[CoL2(CH3CN)2]+. A combination of electrochemical, electrospray mass spectrometry, and 59Co\\/77Se NMR experiments confirms that the binuclear species, [Co2L5]+, reacts with acetonitrile forming CoL3 and [CoL2(CH3CN)2]+. At the electrode surface, CoL3 species generated by this

  15. Electrochemical enhancement of nitric oxide removal from simulated lean-burn engine exhaust via solid oxide fuel cells.

    PubMed

    Huang, Ta-Jen; Wu, Chung-Ying; Lin, Yu-Hsien

    2011-07-01

    A solid oxide fuel cell (SOFC) unit is constructed with Ni-YSZ as the anode, YSZ as the electrolyte, and La(0.6)Sr(0.4)CoO(3)-Ce(0.9)Gd(0.1)O(1.95) as the cathode. The SOFC operation is performed at 600 °C with a cathode gas simulating the lean-burn engine exhaust and at various fixed voltage, at open-circuit voltage, and with an inert gas flowing over the anode side, respectively. Electrochemical enhancement of NO decomposition occurs when an operating voltage is generated; higher O(2) concentration leads to higher enhancement. Smaller NO concentration results in larger NO conversion. Higher operating voltage and higher O(2) concentration can lead to both higher NO conversion and lower fuel consumption. The molar rate of the consumption of the anode fuel can be very much smaller than that of NO to N(2) conversion. This makes the anode fuel consumed in the SOFC-DeNO(x) process to be much less than the equivalent amount of ammonia consumed in the urea-based selective catalytic reduction process. Additionally, the NO conversion increases with the addition of propylene and SO(2) into the cathode gas. These are beneficial for the application of the SOFC-DeNO(x) technology on treating diesel and other lean-burn engine exhausts. PMID:21667969

  16. Electrochemical oxidation of 2-pyrimidinethiols and theoretical study of their dimers, disulfides, sulfenyl radicals, and tautomers.

    PubMed

    Freeman, Fillmore; Po, Henry N; Ho, Thach S; Wang, Ximeng

    2008-02-21

    The relative energies and structures of 2-pyrimidinethiol (1), 4-methyl-2-pyrimidinethiol (3), 5-methyl-2-pyrimidinethiol (5), and 4,6-dimethylpyrimidinethiol (7), and their dimers, disulfides, sulfenyl radicals, and tautomers have been studied using restricted and unrestricted ab initio theory, density functional theory, complete basis set methods, coupled cluster theory, and quadratic configuration interaction calculations. The electrochemical oxidation of 2-pyrimidinethiol (1), 4-methyl-2-pyrimidinethiol (3), and 4,6-dimethylpyrimidinethiol (7) in ethanenitrile affords the respective disulfides in excellent yields. The less polar 2-pyrimidinethiol tautomers are predicted to be the dominant species in the gas phase. CBS-QB3, CBS-Q, CCD, CCSD(T), QCISD(T), and MP2 predict the energy difference (Erel) between (1) and its tautomer (2-pyrimidinethione, 2) to be in the narrow range from 7.23 to 7.87 kcal/mol. Similar trends are observed in the Erel values for the respective tautomers of 2-pyrimidinethiols (3), (5), and (7). The hybrid density functionals B3LYP, B3P86, B3PW91, and MPW1PW91 predict smaller values for Erel between the tautomers than any of the other models. Substitution of methyl groups at positions 4 and 6 of the pyrimidine ring lowers the energy difference between the respective tautomers while a methyl group at position 5 has little effect. The 2-pyrimidinethiol dimer (13) is predicted to be 5.52 and 4.12 kcal/mol, respectively, lower in energy than the isomeric 2-pyrimidinethione dimer (14) and heterodimer (15). The intramolecular four center transition states (TS1) for the tautomerization of 2-pyrimidinethiols (1, 3a, 3b, 5, and 7) in the gas phase have activation barriers of 34.84, 34.42, 34.02, 35.16, and 33.64 kcal/mol, respectively. Alternative lower energy pathways for tautomerism in the gas phase involve dimers and dimer transition states. Dimers and dimer transition states are also involved in the electrochemical oxidation of the 2-pyrimidinethiols. The APT, Mulliken (MPA), and NBO partial atomic charges are compared with the CHELPG and MKS charges that give the most consistent and similar results. PMID:18220373

  17. More accurate macro-models of solid oxide fuel cells through electrochemical and microstructural parameter estimation - Part II: Parameter estimation

    NASA Astrophysics Data System (ADS)

    Boigues-Muñoz, Carlos; Pumiglia, Davide; McPhail, Stephen J.; Santori, Giulio; Montinaro, Dario; Comodi, Gabriele; Carlini, Maurizio; Polonara, Fabio

    2015-07-01

    This paper presents a systematic synergetic approach between experimental measurements, equivalent circuit modelling (described in Part I) and macro-scale modelling theory which has proved to be instrumental for the estimation of microstructural and electrochemical features of a Ni-YSZ|YSZ|Pr2NiO4+? - GDC solid oxide fuel cell (SOFC). The aforementioned parameters have been used to generate a more accurate CFD macro-model which has been validated against the experimental results (presented in Part III).

  18. Studies on electrochemical oxidation of non-aqueous electrolyte on the LiCoO 2 thin film electrode

    Microsoft Academic Search

    Kiyoshi Kanamura; Shigetaka Toriyama; Soshi Shiraishi; Masahiro Ohashi; Zen-ichiro Takehara

    1996-01-01

    In this study, we demonstrated an in situ FTIR measurement for an electrochemical oxidation of propylene carbonate with 1.0 mol dm?3 LiClO4 on LiCoO2 cathode active material used in rechargeable lithium batteries. A thin film electrode of LiCoO2 was prepared by an r.f. sputtering method. The prepared LiCoO2 film had high quality as an electrode for the in situ FTIR

  19. The electrochemical oxidation of troxerutin and its sensitive determination in pharmaceutical dosage forms at PVP modified carbon paste electrode

    Microsoft Academic Search

    Xiaofeng Yang; Fang Wang; Shengshui Hu

    2006-01-01

    The voltammetric responses of troxerutin were investigated at polyvinylpyrrolidone (cross-linked) (PVP) modified carbon paste electrode (CPE) in 0.1mol\\/L KCl by several electrochemical techniques. A well-defined oxidation peak was observed at about 0.97V. Compared with poor responses of troxerutin at bare electrode that at this modified electrode has been greatly improved. It is PVP that enhances the adsorption of troxerutin to

  20. Electrochemical behaviour of stainless steels in media containing iron-oxidizing bacteria (IOB) by corrosion process modeling

    Microsoft Academic Search

    J. Starosvetsky; D. Starosvetsky; B. Pokroy; T. Hilel; R. Armon

    2008-01-01

    Localized corrosion mechanism of stainless steel (SS) types UNS S30403 and UNS 31603 in the presence of iron-oxidizing bacteria Sphaerotilus spp. isolated from rust deposits was studied electrochemically. OCP transient, cyclic anodic and cathodic potentiodynamic polarization curves were measured on steel electrodes through their exposure to 3% NaCl solution supplemented with Sphaerotilus culture. The exposure period was composed of three

  1. 3D CFD Electrochemical and Heat Transfer Model of an Integrated-Planar Solid Oxide Electrolysis Cells

    Microsoft Academic Search

    Grant Hawkes; James E. OBrien

    2008-01-01

    A three-dimensional computational fluid dynamics (CFD) electrochemical model has been created to model high-temperature electrolysis cell performance and steam electrolysis in a new novel integrated planar porous-tube supported solid oxide electrolysis cell (SOEC). The model is of several integrated planar cells attached to a ceramic support tube. This design is being evaluated with modeling at the Idaho National Laboratory. Mass,

  2. In-situ X-Ray Absorption Spectroscopy (XAS) Investigation of a Bifunctional Manganese Oxide Catalyst with High Activity for Electrochemical Water Oxidation and Oxygen Reduction

    PubMed Central

    Benck, Jesse D.; Gul, Sheraz; Webb, Samuel M.; Yachandra, Vittal K.; Yano, Junko; Jaramillo, Thomas F.

    2013-01-01

    In-situ x-ray absorption spectroscopy (XAS) is a powerful technique that can be applied to electrochemical systems, with the ability to elucidate the chemical nature of electrocatalysts under reaction conditions. In this study, we perform in-situ XAS measurements on a bifunctional manganese oxide (MnOx) catalyst with high electrochemical activity for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). Using x-ray absorption near edge structure (XANES) and extended x-ray absorption fine structure (EXAFS), we find that exposure to an ORR-relevant potential of 0.7 V vs. RHE produces a disordered Mn3II,III,IIIO4 phase with negligible contributions from other phases. After the potential is increased to a highly anodic value of 1.8 V vs. RHE, relevant to the OER, we observe an oxidation of approximately 80% of the catalytic thin film to form a mixed MnIII,IV oxide, while the remaining 20% of the film consists of a less oxidized phase, likely corresponding to unchanged Mn3II,III,IIIO4. XAS and electrochemical characterization of two thin film catalysts with different MnOx thicknesses reveals no significant influence of thickness on the measured oxidation states, at either ORR or OER potentials, but demonstrates that the OER activity scales with film thickness. This result suggests that the films have porous structure, which does not restrict electrocatalysis to the top geometric layer of the film. As the portion of the catalyst film that is most likely to be oxidized at the high potentials necessary for the OER is that which is closest to the electrolyte interface, we hypothesize that the MnIII,IV oxide, rather than Mn3II,III,IIIO4, is the phase pertinent to the observed OER activity. PMID:23758050

  3. Oxidation of alloys targeted for advanced steam turbines

    SciTech Connect

    Holcomb, G.R.; Covino, B.S., Jr.; Bullard, S.J.; Ziomek-Moroz, M.; Alman, D.E.

    2006-03-12

    Ultra supercritical (USC) power plants offer the promise of higher efficiencies and lower emissions. Current goals of the U.S. Department of Energy’s Advanced Power Systems Initiatives include coal generation at 60% efficiency, which would require steam temperatures of up to 760°C. This research examines the steamside oxidation of alloys for use in USC systems, with emphasis placed on applications in high- and intermediate-pressure turbines.

  4. Sewage sludge treatment using microwave-enhanced advanced oxidation process

    Microsoft Academic Search

    Gui Q. Yin; Ping H. Liao; Kwang V. Lo

    2008-01-01

    A microwave-enhanced advanced oxidation process using hydrogen peroxide (MW\\/H2O2-AOP) was used for the release of nutrients and the destruction of solids from secondary municipal sewage sludge in this study. Using a computer statistical software package for designing experiments and for data analyses, four factors including microwave heating temperature, heating time, hydrogen peroxide dosage, and sludge solids content were examined. Experiments

  5. INDUSTRIAL WASTEWATER TREATMENT BY AN ADVANCED OXIDATION PROCESS

    Microsoft Academic Search

    Richard Vijay Basker Gunukula; Marty E. Tittlebaum

    2001-01-01

    The overall objective of this study was to evaluate an advanced oxidation process (AOP) used to treat oil and grease (O&G), total petroleum hydrocarbons (TPH), and chemical oxygen demand (COD) of industrial wastewaters generated during barge cleaning operations. This wastewater generally contains appreciable concentrations of O&G, TPH, COD, biochemical oxygen demand (BOD) and benzene, toluene, ethylbenzene and xylene (BTEX) compounds.A

  6. Disinfection of Sewage Sludge Using Microwave Enhanced Advanced Oxidation Process

    Microsoft Academic Search

    Y. Yu; K. V. Lo; P. H. Liao

    2009-01-01

    The microwave enhanced advanced oxidation process (MW\\/H2O2-AOP) was used to treat municipal sewage sludge for pathogen destruction. Two levels of microwave heating temperatures of 55degC and 70degC, and six levels of hydrogen peroxide dosages (0% to 0.1%) were used. Fecal coliform concentrations were found below detection limit (1000 CFU\\/L) immediately after treatment when sludge was treated at 70degC with more

  7. A novel approach for analyzing electrochemical properties of mixed conducting solid oxide fuel cell anode materials by impedance spectroscopy.

    PubMed

    Nenning, A; Opitz, A K; Huber, T M; Fleig, J

    2014-10-28

    For application of acceptor-doped mixed conducting oxides as solid oxide fuel cell (SOFC) anodes, high electrochemical surface activity as well as acceptable electronic and ionic conductivity are crucial. In a reducing atmosphere, particularly the electronic conductivity of acceptor-doped oxides can become rather low and the resulting complex interplay of electrochemical reactions and charge transport processes makes a mechanistic interpretation of impedance measurements very complicated. In order to determine all relevant resistive and capacitive contributions of mixed conducting electrodes in a reducing atmosphere, a novel electrode design and impedance-based analysis technique is therefore introduced. Two interdigitating metallic current collectors are placed in a microelectrode, which allows in-plane measurements within the electrode as well as electrochemical measurements versus a counter electrode. Equivalent circuit models for quantifying the spectra of both measurement modes are developed and applied to simultaneously fit both spectra, using the same parameter set. In this manner, the electronic and ionic conductivity of the material as well as the area-specific resistance of the surface reaction and the chemical capacitance can be determined on a single microelectrode in a H2-H2O atmosphere. The applicability of this new tool was demonstrated in SrTi0.7Fe0.3O(3-?) (STFO) thin film microelectrodes, deposited on single-crystalline yttria-stabilized zirconia (YSZ) substrates. All materials parameters that contribute to the polarization resistance of STFO electrodes in a reducing atmosphere could thus be quantified. PMID:25219525

  8. Electrochemical quartz crystal microbalance, voltammetry, spectroelectrochemical, and microscopic studies of adsorption behavior for (7E,7â²Z)-diphenyl-7,7â²-diapocarotene electrochemical oxidation product

    Microsoft Academic Search

    Guoqiang Gao; David B. Wurm; Yeon-Taik Kim; Lowell D. Kispert

    1997-01-01

    Polymeric products, which are formed by reaction of the dications of (7E,7â²Z)-diphenyl-7,7â²-diapocarotene (I) generated by electrochemical oxidation in dichloromethane with the neutral carotenoid, are adsorbed on various electrode surfaces. An apparent average molar mass of 5400 g\\/(mol electrons) was calculated from simultaneous electrochemical quartz crystal microbalance (EQCM) measurements, and the green, fiber-like structure observed by optical microscopy confirms the formation

  9. Electrochemical detection in a microfluidic device of oxidative stress generated by macrophage cells.

    PubMed

    Amatore, Christian; Arbault, Stéphane; Chen, Yong; Crozatier, Cécile; Tapsoba, Issa

    2007-02-01

    The release of reactive oxygen species (ROS) or reactive nitrogen species (RNS), i.e., the initial phase of oxidative stress, by macrophage cells has been studied by electrochemistry within a microfluidic device. Macrophages were first cultured into a detection chamber containing the three electrodes system and were subsequently stimulated by the microinjection of a calcium ionophore (A23187). Their production of ROS and RNS was then measured by amperometry at the surface of a platinized microelectrode. The fabricated microfluidic device provides an accurate measurement of oxidative release kinetics with an excellent reproducibility. We believe that such a method is simple and versatile for a number of advanced applications based on the detection of biological processes of secretion by a few or even a single living cell. PMID:17268626

  10. Mediated electrochemical oxidation of organic wastes using a Co (III) mediator in a nitric acid based system

    DOEpatents

    Balazs, G.B.; Chiba, Z.; Lewis, P.R.; Nelson, N.; Steward, G.A.

    1999-06-15

    An electrochemical cell with a Co(III) mediator and nitric acid electrolyte provides efficient destruction of organic and mixed wastes. The organic waste is concentrated in the anolyte reservoir, where the mediator oxidizes the organics and insoluble transuranic compounds and is regenerated at the anode until the organics are converted to CO[sub 2]. The nitric acid is an excellent oxidant that facilitates the destruction of the organic components. The anode is not readily attacked by the nitric acid solution, thus the cell can be used for extended continual operation without electrode replacement. 2 figs.

  11. Mediated electrochemical oxidation of organic wastes using a Co (III) mediator in a nitric acid based system

    DOEpatents

    Balazs, G. Bryan (Livermore, CA); Chiba, Zoher (Moraga, CA); Lewis, Patricia R. (Livermore, CA); Nelson, Norvell (Palo Alto, CA); Steward, G. Anthony (Los Altos Hills, CA)

    1999-01-01

    An electrochemical cell with a Co(III) mediator and nitric acid electrolyte provides efficient destruction of organic and mixed wastes. The organic waste is concentrated in the anolyte reservoir, where the mediator oxidizes the organics and insoluble transuranic compounds and is regenerated at the anode until the organics are converted to CO.sub.2. The nitric acid is an excellent oxidant that facilitates the destruction of the organic components. The anode is not readily attacked by the nitric acid solution, thus the cell can be used for extended continual operation without electrode replacement.

  12. Alloys for advanced steam turbines--Oxidation behavior

    SciTech Connect

    Holcomb, G.R.

    2007-10-01

    Advanced or ultra supercritical (USC) steam power plants offer the promise of higher efficiencies and lower emissions. Current goals of the U.S. Department of Energy (DOE) include power generation from coal at 60% efficiency, which would require steam temperatures of up to 760°C. Current research on the oxidation of candidate materials for advanced steam turbines is presented with a focus on a methodology for estimating chromium evaporation rates from protective chromia scales. The high velocities and pressures of advanced steam turbines lead to evaporation predictions as high as 5 × 10-8 kg m-2s-1 of CrO2(OH)2(g) at 760°C and 34.5 MPa. This is equivalent to 0.077 mm per year of solid Cr loss.

  13. Synthesis of Au/Graphene Oxide Composites for Selective and Sensitive Electrochemical Detection of Ascorbic Acid

    PubMed Central

    Song, Jian; Xu, Lin; Xing, Ruiqing; Li, Qingling; Zhou, Chunyang; Liu, Dali; Song, Hongwei

    2014-01-01

    In this work, we present a novel ascorbic acid (AA) sensor applied to the detection of AA in human sera and pharmaceuticals. A series of Au nanoparticles (NPs) and graphene oxide sheets (Au NP/GO) composites were successfully synthesized by reduction of gold (III) using sodium citrate. Then the Au NP/GO composites were used to construct nonenzymatic electrodes in practical AA measurement. The electrode that has the best performance presents attractive analytical features, such as a low working potential of +0.15?V, a high sensitivity of 101.86??A mM?1 cm?2 to AA, a low detection limit of 100?nM, good reproducibility and excellent selectivity. And more,it was also employed to accurately and practically detect AA in human serum and clinical vitamin C tablet with the existence of some food additive. The enhanced AA electrochemical properties of the Au NP/GO modified electrode in our work can be attributed to the improvement of electroactive surface area of Au NPs and the synergistic effect from the combination of Au NPs and GO sheets. This work shows that the Au NP/GO/GCEs hold the prospect for sensitive and selective determination of AA in practical clinical application. PMID:25515430

  14. Seedless growth of zinc oxide flower-shaped structures on multilayer graphene by electrochemical deposition

    NASA Astrophysics Data System (ADS)

    Aziz, Nur Suhaili Abd; Nishiyama, Tomoya; Rusli, Nurul Izni; Mahmood, Mohamad Rusop; Yasui, Kanji; Hashim, Abdul Manaf

    2014-07-01

    A seedless growth of zinc oxide (ZnO) structures on multilayer (ML) graphene by electrochemical deposition without any pre-deposited ZnO seed layer or metal catalyst was studied. A high density of a mixture of vertically aligned/non-aligned ZnO rods and flower-shaped structures was obtained. ML graphene seems to generate the formation of flower-shaped structures due to the stacking boundaries. The nucleation of ZnO seems to be promoted at the stacking edges of ML graphene with the increase of applied current density, resulting in the formation of flower-shaped structures. The diameters of the rods/flower-shaped structures also increase with the applied current density. ZnO rods/flower-shaped structures with high aspect ratio over 5.0 and good crystallinity were obtained at the applied current densities of -0.5 and -1.0 mA/cm2. The growth mechanism was proposed. The growth involves the formation of ZnO nucleation below 80°C and the enhancement of the growth of vertically non-aligned rods and flower-shaped structures at 80°C. Such ZnO/graphene hybrid structure provides several potential applications in sensing devices.

  15. Magnetic behaviors of cerium oxide-based thin films deposited using electrochemical method

    NASA Astrophysics Data System (ADS)

    Peng, Ying-Zi; Li, Yuan; Bai, Ru; Huo, De-Xuan; Qian, Zheng-Hong

    2014-09-01

    Zn and Co multi-doped CeO2 thin films have been prepared using an anodic electrochemical method. The structures and magnetic behaviors are characterized by several techniques, in which the oxygen states in the lattice and the absorptive oxygen bonds at the surface are carefully examined. The absorptive oxygen bond is about 50% of the total oxygen bond by using a semi-quantitative method. The value of actual stoichiometry ?' is close to 2. The experimental results indicate that the thin films are of a cerium oxide-based solid solution with few oxygen vacancies in the lattice and many absorptive oxygen bonds at the surface. Week ferromagnetic behaviors were evidenced by observed M—H hysteresis loops at room temperature. Furthermore, an evidence of relative ferromagnetic contributions was revealed by the temperature dependence of magnetization. It is believed that the ferromagnetic contributions exhibited in the M—H loops originate from the absorptive oxygen on the surface rather than the oxygen vacancies in the lattice.

  16. Electrochemical and biological characterization of coatings formed on Ti-15Mo alloy by plasma electrolytic oxidation.

    PubMed

    Kazek-K?sik, Alicja; Krok-Borkowicz, Ma?gorzata; Pamu?a, El?bieta; Simka, Wojciech

    2014-10-01

    ?-Type titanium alloys are considered the future materials for bone implants. To improve the bioactivity of Ti-15Mo, the surface was modified using the plasma electrolytic oxidation (PEO) process. Tricalcium phosphate (TCP, Ca3PO4), wollastonite (CaSiO3) and silica (SiO2) were selected as additives in the anodizing bath to enhance the bioactivity of the coatings formed during the PEO process. Electrochemical analysis of the samples was performed in Ringer's solution at 37°C. The open-circuit potential (EOCP) as a function of time, corrosion potential (ECORR), corrosion current density (jCORR) and polarization resistance (Rp) of the samples were determined. Surface modification improved the corrosion resistance of Ti-15Mo in Ringer's solution. In vitro studies with MG-63 osteoblast-like cells were performed for 1, 3 and 7 days. After 24h, the cells were well adhered on the entire surfaces, and their number increased with increasing culture time. The coatings formed in basic solution with wollastonite exhibited better biological performance compared with the as-ground sample. PMID:25175202

  17. Electrochemical oxidation of methanol over a silver electrode deposited on yttria-stabilized zirconia electrolyte

    SciTech Connect

    Hong, Jin Ki; Oh, In-Hwan; Hong, Seong-Ahn; Lee, Wha Young [Seoul National Univ. (Korea, Republic of)] [Seoul National Univ. (Korea, Republic of); [Korea Institute of Science and Technology, Seoul (Korea, Republic of)

    1996-09-15

    A solid electrolyte catalytic reactor was used to investigate the change in catalytic activity of the electrode upon conduction of O{sup 2{minus}} ions through the electrolyte. The reactor consisted of an yttria-stabilized zirconia electrolyte disk on which a thin film of the Ag electrode was deposited. As the catalyst potential was applied below the open circuit potential or, equivalently, as O{sup 2{minus}} ions were electrochemically removed from the Ag catalyst electrode to the counter electrode through the solid electrolyte, its influence on the O{sub 2} exchange reaction in He-O{sub 2} flow and CH{sub 3}OH oxidation to HCHO and CO{sub 2} in He-O{sub 2}-CH{sub 3}OH flow was investigated. It was found from the O{sub 2} exchange reaction study that slow diffusion of adsorbed oxygen to the catalyst electrolyte-gas three-phase boundary, where charge transfer took place, caused a limiting current. In CH{sub 3}OH oxidation, a lowered open circuit potential was observed when CH{sub 3}OH was added to the He-O{sub 2} flow. Lowering the catalyst potential below this new open circuit potential was found to cause a reversible, somewhat nonfaradaic increase in the rate of CO{sub 2} formation, but had little effect on the rate of HCHO formation. Based on the rate equations, this behavior was interpreted in terms of an activated surface reaction between adsorbed species due to the change in the catalyst work function with changing catalyst potential. 27 refs., 10 figs., 3 tabs.

  18. Optical and electrochemical properties of polyether derivatives of perylenediimides adsorbed on nanocrystalline metal oxide films

    Microsoft Academic Search

    Mahmut Kus; Özgül Hakli; Ceylan Zafer; Canan Varlikli; Serafettin Demic; Serdar Özçelik; Siddik Icli

    2008-01-01

    We report optical and electrochemical properties of polyether derivatives of perylenediimides (PDIs) thin films formed in various materials (semiconductor, insulator, amorphous and self-assembly). Perylenediimides adsorbed on nanocrystalline TiO2 (NT) nanocrystalline alumina (NA), amorphous silicon (PS) and neat self-assemblied (SA) films were prepared and characterized based on spectroscopic, electrochemical, spectro-electrochemical techniques. The absorption and fluorescence spectra of PDIs in chloroform exhibit

  19. Nitrogen doped holey graphene as an efficient metal-free multifunctional electrochemical catalyst for hydrazine oxidation and oxygen reduction

    NASA Astrophysics Data System (ADS)

    Yu, Dingshan; Wei, Li; Jiang, Wenchao; Wang, Hong; Sun, Bo; Zhang, Qiang; Goh, Kunli; Si, Rongmei; Chen, Yuan

    2013-03-01

    Electrocatalysts for anode or cathode reactions are at the heart of electrochemical energy conversion and storage devices. Molecular design of carbon based nanomaterials may create the next generation electrochemical catalysts for broad applications. Herein, we present the synthesis of a three-dimensional (3D) nanostructure with a large surface area (784 m2 g-1) composed of nitrogen doped (up to 8.6 at.%) holey graphene. The holey structure of graphene sheets (~25% of surface area is attributed to pores) engenders more exposed catalytic active edge sites. Nitrogen doping further improves catalytic activity, while the formation of the 3D porous nanostructure significantly reduces graphene nanosheet stacking and facilitates the diffusion of reactants/electrolytes. The three factors work together, leading to superb electrochemical catalytic activities for both hydrazine oxidation (its current generation ability is comparable to that of 10 wt% Pt-C catalyst) and oxygen reduction (its limiting current is comparable to that of 20 wt% Pt-C catalyst) with four-electron transfer processes and excellent durability.Electrocatalysts for anode or cathode reactions are at the heart of electrochemical energy conversion and storage devices. Molecular design of carbon based nanomaterials may create the next generation electrochemical catalysts for broad applications. Herein, we present the synthesis of a three-dimensional (3D) nanostructure with a large surface area (784 m2 g-1) composed of nitrogen doped (up to 8.6 at.%) holey graphene. The holey structure of graphene sheets (~25% of surface area is attributed to pores) engenders more exposed catalytic active edge sites. Nitrogen doping further improves catalytic activity, while the formation of the 3D porous nanostructure significantly reduces graphene nanosheet stacking and facilitates the diffusion of reactants/electrolytes. The three factors work together, leading to superb electrochemical catalytic activities for both hydrazine oxidation (its current generation ability is comparable to that of 10 wt% Pt-C catalyst) and oxygen reduction (its limiting current is comparable to that of 20 wt% Pt-C catalyst) with four-electron transfer processes and excellent durability. Electronic supplementary information (ESI) available: AFM images of GO sheets, nitrogen physisorption isotherms, XPS spectrum of RG, RDE curves of electrodes, CV curves of electrodes, and determination of the number of total electrons (n) involved in hydrazine oxidation. See DOI: 10.1039/c3nr34267k

  20. Electrochemical and spectroscopic studies of some less stable oxidation states of selected lanthanide and actinide elements

    SciTech Connect

    Hobart, D. E.

    1981-06-01

    Simultaneous observation of electrochemical and spectroscopic properties (spectroelectrochemistry) at optically transparent electrodes (OTE's) was used to study some less stable oxidation states of selected lanthanide and actinide elements. Cyclic voltammetry at microelectrodes was used in conjunction with spectroelectrochemistry for the study of redox couples. Additional analytical techniques were used. The formal reduction potential (E/sup 0/') values of the M(III)/M(II) redox couples in 1 M KCl at pH 6 were -0.34 +- 0.01 V for Eu, -1.18 +- 0.01 V for Yb, and -1.50 +- 0.01 V for Sm. Spectropotentiostatic determination of E/sup 0/' for the Eu(III)/Eu(II) redox couple yielded a value of -0.391 +- 0.005 V. Spectropotentiostatic measurement of the Ce(IV)/Ce(III) redox couple in concentrated carbonate solution gave E/sup 0/' equal to 0.051 +- 0.005 V, which is about 1.7 V less positive than the E/sup 0/' value in noncomplexing solution. This same difference in potential was observed for the E/sup 0/' values of the Pr(IV)/Pr(III) and Tb(IV)/Tb(III) redox couples in carbonate solution, and thus Pr(IV) and Tb(IV) were stabilized in this medium. The U(VI)/U(V)/U(IV) and U(IV)/U(III) redox couples were studied in 1 M KCl at OTE's. Spectropotentiostatic measurement of the Np(VI)/Np(V) redox couple in 1 M HClO/sub 4/ gave an E/sup 0/' value of 1.140 +- 0.005 V. An E/sup 0/' value of 0.46 +- 0.01 V for the Np(VII)/Np(VI) couple was found by voltammetry. Oxidation of Am(III) was studied in concentrated carbonate solution, and a reversible cyclic voltammogram for the Am(IV)/Am(III) couple yielded E/sup 0/' = 0.92 +- 0.01 V in this medium; this value was used to estimate the standard reduction potential (E/sup 0/) of the couple as 2.62 +- 0.01 V. Attempts to oxidize Cm(III) in concentrated carbonate solution were not successful which suggests that the predicted E/sup 0/ value for the Cm(IV)/Cm(III) redox couple may be in error.

  1. Screen-printed calcium-birnessite electrodes for water oxidation at neutral pH and an "electrochemical harriman series".

    PubMed

    Lee, Seung Y; González-Flores, Diego; Ohms, Jonas; Trost, Tim; Dau, Holger; Zaharieva, Ivelina; Kurz, Philipp

    2014-12-01

    A mild screen-printing method was developed to coat conductive oxide surfaces (here: fluorine-doped tin oxide) with micrometer-thick layers of presynthesized calcium manganese oxide (Ca-birnessite) particles. After optimization steps concerning the printing process and layer thickness, electrodes were obtained that could be used as corrosion-stable water-oxidizing anodes at pH?7 to yield current densities of 1?mA?cm(-2) at an overpotential of less than 500?mV. Analyses of the electrode coatings of optimal thickness (?10??m) indicated that composition, oxide phase, and morphology of the synthetic Ca-birnessite particles were hardly affected by the screen-printing procedure. However, a more detailed analysis by X-ray absorption spectroscopy revealed small modifications of both the Mn redox state and the structure at the atomic level, which could affect functional properties such as proton conductivity. Furthermore, the versatile new screen-printing method was used for a comparative study of various transition-metal oxides concerning electrochemical water oxidation under "artificial leaf conditions" (neutral pH, fairly low overpotential and current density), for which a general activity ranking of RuO2 >Co3 O4 ?(Ca)MnOx ?NiO was observed. Within the group of screened manganese oxides, Ca-birnessite performed better than "Mn-only materials" such as Mn2 O3 and MnO2 . PMID:25346273

  2. Laser cleaning of oxide iron layer: Efficiency enhancement due to electrochemical induced absorptivity change

    Microsoft Academic Search

    P. Pasquet; R. del Coso; J. Boneberg; P. Leiderer; R. Oltra; J. P. Boquillon

    1999-01-01

    Laser cleaning experiments exhibited a higher cleaning efficiency of the laser cleaning upon application of electrochemical potential on an oxidised iron surface. The objective of this study is to clarify the role of such an electrochemical control on cleaning efficiency. Therefore a study by optical spectrometry at normal incidence in the relevant conditions was performed. From these measurements the optical

  3. Highly dispersible and stable copper terephthalate metal-organic framework-graphene oxide nanocomposite for an electrochemical sensing application.

    PubMed

    Wang, Xia; Wang, Qingxiang; Wang, Qinghua; Gao, Feng; Gao, Fei; Yang, Yizhen; Guo, Hongxu

    2014-07-23

    A highly dispersible and stable nanocomposite of Cu(tpa)-GO (Cu(tpa) = copper terephthalate metal-organic framework, GO = graphene oxide) was prepared through a simple ultrasonication method. The morphology and structure of the obtained composite were characterized via scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis, Fourier-transform infrared (FT-IR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). On the basis of the characterization results, the binding mechanism of the Cu(tpa) and GO was speculated to be the cooperative interaction of ?-? stacking, hydrogen bonding, and Cu-O coordination. The electrochemical sensing property of Cu(tpa)-GO composite was investigated through casting the composite on a glassy carbon electrode (GCE), followed by an electro-reduction treatment to transfer the GO in the composite to the highly conductive reduced form (electrochemically reduced graphene, EGR). The results demonstrated that the electrochemical signals and peak profiles of the two drugs of acetaminophen (ACOP) and dopamine (DA) were significantly improved by the modified material, owing to the synergistic effect from high conductivity of EGR and unique electron mediating action of Cu(tpa). Under the optimum conditions, the oxidation peak currents of ACOP and DA were linearly correlated to their concentrations in the ranges of 1-100 and 1-50 ?M, respectively. The detection limits for ACOP and DA were estimated to be as low as 0.36 and 0.21 ?M, respectively. PMID:25000168

  4. Electrochemical detection of Cu2+ through Ag nanoparticle assembly regulated by copper-catalyzed oxidation of cysteamine.

    PubMed

    Cui, Lin; Wu, Jie; Li, Jie; Ge, Yanqiu; Ju, Huangxian

    2014-05-15

    A highly sensitive and selective electrochemical sensor was developed for the detection of Cu(2+) by the assembly of Ag nanoparticles (AgNPs) at dithiobis[succinimidylpropionate] encapsulated Au nanoparticles (DSP-AuNPs), which was regulated by copper-catalyzed oxidation of cysteamine (Cys). The electrochemical sensor was constructed by layer-by-layer modification of glassy carbon electrode with carbon nanotubes, poly(amidoamine) dendrimers and DSP-AuNPs. In the absence of Cu(2+), Cys could bind to the surface of citrate-stabilized AgNPs via Ag-S bond, thus AgNPs could be assembled on the sensor surface through the reaction between DSP and Cys. In contrast, the copper-catalyzed oxidation of Cys by dissolved oxygen in the presence of Cu(2+) inhibited the Cys-induced aggregation of AgNPs, leading to the decrease of the electrochemical stripping signal of AgNPs. Under the optimized conditions, this method could detect Cu(2+) in the range of 1.0-1000 nM with a detection limit of 0.48 nM. The proposed Cu(2+) sensor showed good reproducibility, stability and selectivity. It has been satisfactorily applied to determine Cu(2+) in water samples. PMID:24389390

  5. Electrostatic and electrochemical nature of liquid-gated electric-double-layer transistors based on oxide semiconductors.

    PubMed

    Yuan, Hongtao; Shimotani, Hidekazu; Ye, Jianting; Yoon, Sungjae; Aliah, Hasniah; Tsukazaki, Atsushi; Kawasaki, Masashi; Iwasa, Yoshihiro

    2010-12-29

    The electric-double-layer (EDL) formed at liquid/solid interfaces provides a broad and interdisciplinary attraction in terms of electrochemistry, photochemistry, catalysts, energy storage, and electronics because of the large interfacial capacitance coupling and its ability for high-density charge accumulation. Much effort has recently been devoted to the fundamental understanding and practical applications of such highly charged EDL interfaces. However, the intrinsic nature of the EDL charging, whether it is electrostatics or electrochemistry, and how to distinguish them are far from clear. Here, by combining electrical transport measurements with electrochemical impedance spectroscopy (EIS), we studied the charging mechanisms of highly charged EDL interfaces between an ionic liquid and oxide semiconductor, ZnO. The direct measure for mobile carriers from the Hall effect agreed well with that from the capacitance-voltage integration at 1 Hz, implying that the pseudocapacitance does not contribute to carrier transport at EDL interfaces. The temperature-frequency mapping of EIS was further demonstrated as a "phase diagram" to distinguish the electrostatic or electrochemical nature of such highly charged EDL interfaces with densities of up to 8 × 10(14) cm(-2), providing a guideline for electric-field-induced electronic phenomena and a simple method for distinguishing electrostatic and electrochemical charging in EDLTs not only based on a specific oxide semiconductor, ZnO, but also commonly applicable to all types of EDL interfaces with extremely high-density carrier accumulation. PMID:21141862

  6. Optical and electrochemical properties of ethynylaniline derivatives of phenothiazine, phenothiazine-5-oxide and phenothiazine-5,5-dioxide.

    PubMed

    Thériault, Kim D; Sutherland, Todd C

    2014-06-28

    Three phenothiazine (PTZ) derivatives with varying degrees of sulfur oxidation states were synthesized as strong electron donors. The thioether, sulfoxide and sulfone PTZ-derivatives exhibited irreversible oxidation at 0.19 V, 0.29 V and 0.31 V versus ferrocene, respectively. Each PTZ derivative was emissive with lifetimes of 1.7 ns, 0.5 ns, and 0.5 ns and absolute quantum yields of 0.32, 0.23 and 0.23 for the thioether, sulfoxide and sulfone derivatives, respectively. Furthermore, these PTZ derivatives showed very large Stokes shifts ranging from 5600 cm(-1) to 2800 cm(-1). Calculations using DFT and TD-DFT methods resulted in an optimized ground state and the excited state geometries of the PTZ derivatives that compared favourably to experimental optical and electrochemical data. DFT calculations revealed that these butterfly shaped derivatives flatten upon excitation and this effect is greatest for the thioether PTZ derivative, resulting in the large Stokes shift. These potent electron donor systems also displayed electrochromic behaviour upon oxidation, which was attributed to a delocalized cation over the phenothiazine core and the appended ethynyl anilines. The electrochemically oxidized species had a wide absorption profile spanning from 300 nm to past 800 nm. PMID:24821592

  7. High performance liquid chromatography coupled with post-column electrochemical oxidation for the detection of PSP toxins.

    PubMed

    Boyer, G L; Goddard, G D

    1999-01-01

    High Performance Liquid Chromatography (HPLC) is an important tool for the study of PSP toxins. It provides an alternative to bioassays and gives the concentration of individual toxin isomers. The current HPLC protocol uses a post-column chemical reaction system (PCRS) to oxidize the saxitoxin ring system to form a fluorescent chromophore. This oxidation is sensitive to changes in the flow rate, temperature, pH and age of the reagents. We have previously shown that this oxidation can be accomplished using electrochemical techniques. Termed the electrochemical oxidation system (ECOS), this approach provides a simpler alternative to the traditional PCRS-based HPLC system. A detailed description of the construction and maintenance of an HPLC-ECOS system for the analysis of PSP toxins is presented. Comparisons of the mouse bioassay, HPLC-PCRS and HPLC-ECOS system are presented for three different sample matrices: toxic dinoflagellates (Alexandrium tamarense), geoduck (Panopea generosa) and scallops (Placopectin magellanicus). In all three cases, the correlation of the HPLC-ECOS system to the mouse bioassay is similar to that obtained using the HPLC-PCRS system for the analysis of PSP toxins. PMID:11122529

  8. Metal-Free Dihydrogen Oxidation by a Borenium Cation: A Combined Electrochemical/Frustrated Lewis Pair Approach**

    PubMed Central

    Lawrence, Elliot J; Herrington, Thomas J; Ashley, Andrew E; Wildgoose, Gregory G

    2014-01-01

    In order to use H2 as a clean source of electricity, prohibitively rare and expensive precious metal electrocatalysts, such as Pt, are often used to overcome the large oxidative voltage required to convert H2 into 2?H+ and 2?e?. Herein, we report a metal-free approach to catalyze the oxidation of H2 by combining the ability of frustrated Lewis pairs (FLPs) to heterolytically cleave H2 with the in?situ electrochemical oxidation of the resulting borohydride. The use of the NHC-stabilized borenium cation [(IiPr2)(BC8H14)]+ (IiPr2=C3H2(NiPr)2, NHC=N-heterocyclic carbene) as the Lewis acidic component of the FLP is shown to decrease the voltage required for H2 oxidation by 910?mV at inexpensive carbon electrodes, a significant energy saving equivalent to 175.6?kJ?mol?1. The NHC–borenium Lewis acid also offers improved catalyst recyclability and chemical stability compared to B(C6F5)3, the paradigm Lewis acid originally used to pioneer our combined electrochemical/frustrated Lewis pair approach. PMID:25044562

  9. Electrochemical investigation of chromium oxide-coated Ti-6Al-4V and Co-Cr-Mo alloy substrates.

    PubMed

    Swaminathan, Viswanathan; Zeng, Haitong; Lawrynowicz, Daniel; Zhang, Zongtao; Gilbert, Jeremy L

    2011-08-01

    Hard coatings for articulating surfaces of total joint replacements may improve the overall wear resistance. However, any coating approach must take account of changes in corrosion behavior. This preliminary assessment analyzes the corrosion kinetics, impedance and mechanical-electrochemical stability of 100 ?m thick plasma sprayed chromium oxide (Cr?O?) coatings on bearing surfaces in comparison to the native alloy oxide films on Co-Cr-Mo and Ti-6Al-6V. Cyclic potentiodynamic polarization, electrochemical impedance spectroscopy, and mechanical abrasion under potentiostatic conditions were performed on coated and substrate surfaces in physiological saline. SEM analysis characterized the coating morphology. The results showed that the corrosion current density values of chromium oxide coatings (0.4-1.2 ?A/cm²) were of the same order of magnitude as Ti-6Al-4V alloy. Mechanical abrasion did not increase corrosion rates of chromium oxide coatings but did for uncoated Co-Cr-Mo and Ti-6Al-4V. The impedance response of chromium oxide coatings was very different than Co-Cr-Mo and Ti-6Al-4V native oxides characterized by a defected coating model. More of a frequency-independent purely resistive response was seen in mid-frequency range for the coatings (CPE(coat) : 40-280 nF/cm² (rad/s)(1-?) , ?: 0.67-0.83) whereas a more capacitive character is seen for Co-Cr-Mo and Ti-6Al-4V (CPE(ox) around 20 ?F/cm² (rad/s)(1-?) , ? around 0.9). Pores, interparticle gaps and incomplete fusion typical for thermal spray coatings were present in these oxides which could have influenced corrosion resistance. The coating microstructure could have allowed some fluid penetration. Overall, these coatings appear to have suitable corrosion properties for wear surfaces. PMID:21648063

  10. Hybrid nickel manganese oxide nanosheet-3D metallic dendrite percolation network electrodes for high-rate electrochemical energy storage.

    PubMed

    Nguyen, Tuyen; Eugénio, Sónia; Boudard, Michel; Rapenne, Laetitia; Carmezim, M João; Silva, Teresa M; Montemor, M Fátima

    2015-08-01

    This work reports the fabrication, by electrodeposition and post-thermal annealing, of hybrid electrodes for high rate electrochemical energy storage composed of nickel manganese oxide (Ni0.86Mn0.14O) nanosheets over 3D open porous dendritic NiCu foams. The hybrid electrodes are made of two different percolation networks of nanosheets and dendrites, and exhibit a specific capacitance value of 848 F g(-1) at 1 A g(-1). The electrochemical tests revealed that the electrodes display an excellent rate capability, characterized by capacitance retention of approximately 83% when the applied current density increases from 1 A g(-1) to 20 A g(-1). The electrodes also evidenced high charge-discharge cycling stability, which attained 103% after 1000 cycles. PMID:26135715

  11. Treatment of gasoline-contaminated waters by advanced oxidation processes.

    PubMed

    Tiburtius, Elaine Regina Lopes; Peralta-Zamora, Patricio; Emmel, Alexandre

    2005-11-11

    In this study, the efficiency of advanced oxidative processes (AOPs) was investigated toward the degradation of aqueous solutions containing benzene, toluene and xylenes (BTX) and gasoline-contaminated waters. The results indicated that BTX can be effectively oxidized by near UV-assisted photo-Fenton process. The treatment permits almost total degradation of BTX and removal of more than 80% of the phenolic intermediates at reaction times of about 30 min. Preliminary investigations using water contaminated by gasoline suggest a good potentiality of the process for the treatment of large volumes of aqueous samples containing these polluting species. Heterogeneous photocatalysis and H2O2/UV system show lower degradation efficiency, probably due to the heterogeneous character of the TiO2-mediated system and lost of photonic efficiency of the H2O2/UV system in the presence of highly colored intermediated. PMID:16051429

  12. Electrochemical study of lithiated transition metal oxide composite for single layer fuel cell

    NASA Astrophysics Data System (ADS)

    Hu, Huiqing; Lin, Qizhao; Muhammad, Afzal; Zhu, Bin

    2015-07-01

    This study analyzed the effect of various semiconductors of transition metal oxides in modified lithiated NiO on the electrochemical performance of a single layer fuel cell (SLFC). A typical ionic conductor Ce0.8Sm0.2O2-? (SDC) and three types of semiconductors Li0.3Ni0.6Cu0.07Sr0.03O2-? (LNCuS), Li0.3Ni0.6Mn0.07Sr0.03O2-? (LNMnS) and Li0.3Ni0.6Co0.07Sr0.03O2-? (LNCoS), were the fundamental components of the SLFCs. The components were characterized by using X-ray diffraction (XRD), a scanning electron microscope (SEM), and an energy-dispersive X-ray spectrometer (EDS). The stability of the synthesized materials was evaluated using thermal gravity analysis (TGA). The ohmic resistances at 500 °C were 0.36, 0.48 and 0.58 ? cm2 for 6SDC-4LNMnS, 6SDC-4LNCoS and 6SDC-4LNCuS, respectively. Among the three SLFCs, the single cell with 6SDC-4LNMnS achieves the highest power density (422 mW cm-2) but the lowest temperature stability, while the single cell with 6SDC-4LNCuS achieved the lowest power density (331 mW cm-2) but the highest temperature stability during the operation temperature.

  13. Electrochemically driven biocatalysis of the oxygenase domain of neuronal nitric oxide synthase in indium tin oxide nanoparticles/polyvinyl alcohol nanocomposite.

    PubMed

    Xu, Xuan; Wollenberger, Ulla; Qian, Jing; Lettau, Katrin; Jung, Christiane; Liu, Songqin

    2013-12-01

    Nitric oxide synthase (NOS) plays a critical role in a number of key physiological and pathological processes. Investigation of electron-transfer reactions in NOS would contribute to a better understanding of the nitric oxide (NO) synthesis mechanism. Herein, we describe an electrochemically driven catalytic strategy, using a nanocomposite that consisted of the oxygenase domain of neuronal NOS (D290nNOSoxy), indium tin oxide (ITO) nanoparticles and polyvinyl alcohol (PVA). Fast direct electron transfer between electrodes and D290nNOSoxy was observed with the heterogeneous electron transfer rate constant (ket) of 154.8 ± 0.1s(-1) at the scan rate of 5 Vs(-1). Moreover, the substrate N(?)-hydroxy-L-arginine (NHA) was used to prove the concept of electrochemically driven biocatalysis of D290nNOSoxy. In the presence of the oxygen cosubstrate and tetrahydrobiopterin (BH4) cofactor, the addition of NHA caused the decreases of both oxidation current at +0.1 V and reduction current at potentials ranging from -0.149 V to -0.549 V vs Ag/AgCl. Thereafter, a series of control experiments such as in the absence of BH4 or D290nNOSoxy were performed. All the results demonstrated that D290nNOSoxy biocatalysis was successfully driven by electrodes in the presence of BH4 and oxygen. This novel bioelectronic system showed potential for further investigation of NOS and biosensor applications. PMID:23727770

  14. Electrochemical Sensor Based on Carbon Paste Electrode Modified with Nanostructured Crypotomelane-Type Manganese Oxides for Detection of Heavy Metals

    SciTech Connect

    Cui, Xiaoli; Liu, Guodong; Li, Liyu; Yantasee, Wassana; Lin, Yuehe

    2005-02-03

    A carbon paste electrode modified with nanostructured crypotomelane type manganese oxides was evaluated as new electrochemical sensor for the detection of heavy metal ions in aqueous media. The crypotomelane type manganese oxides are nanofibrous crystals with sub-nanometer tunnels which provide excellent sites for ion-exchanges. The adsorptive stripping voltammetry (ASV) technique involves preconcentration of the metal ions into nanostructured crypotomelane type manganese oxides under an open circuit, then electrolysis of the preconcentrated species, followed by a square-wave potential sweep towards positive values. Factors affecting the preconcentration process were investigated using lead ion as the model analyte. The voltammetric responses increased with the preconcentration time from 2 to 30 min, and also linearly with lead ion concentrations ranging from 50 to 1200 ppb. The detection limits of target metal ion were 10 ppb after 4 min preconcentration and improved to 1 ppb after 20 min preconcentration. The potential for simultaneous detection of copper, silver and lead is also discussed.

  15. A comparison of single oxidants versus advanced oxidation processes as chlorine-alternatives for wild blueberry processing ( Vaccinium angustifolium)

    Microsoft Academic Search

    Kristi M. Crowe; Alfred A. Bushway; Rodney J. Bushway; Katherine Davis-Dentici; Russell A. Hazen

    2007-01-01

    Advanced oxidation processes and single chemical oxidants were evaluated for their antimicrobial efficacy against common spoilage bacteria isolated from lowbush blueberries. Predominant bacterial flora were identified using biochemical testing with the assessment of relative abundance using non-selective and differential media. Single chemical oxidants evaluated for postharvest processing of lowbush blueberries included 1% hydrogen peroxide, 100 ppm chlorine, and 1 ppm aqueous ozone

  16. Electrochemical reduction of silver vanadium phosphorous oxide, Ag 2VO 2PO 4: Silver metal deposition and associated increase in electrical conductivity

    Microsoft Academic Search

    Amy C. Marschilok; Eric S. Kozarsky; Kevin Tanzil; Shali Zhu; Kenneth J. Takeuchi; Esther S. Takeuchi

    2010-01-01

    This report details the chemical and associated electrical resistance changes of silver vanadium phosphorous oxide (Ag2VO2PO4, SVPO) incurred during electrochemical reduction in a lithium based electrochemical cell over the range of 0–4 electrons per formula unit. Specifically the cathode electrical conductivities and associated cell DC resistance and cell AC impedance values vary with the level of reduction, due the changes

  17. Study of a gold electrode modified by trans-[Ru(NH 3) 4(Ist)SO 4] + to produce an electrochemical sensor for nitric oxide

    Microsoft Academic Search

    Vanessa N. Santos; Murilo F. Cabral; Jefferson S. Ferreira; Alda K. M. Holanda; Sergio A. S. Machado; Jackson R. Sousa; Luiz G. F. Lopes; Adriana N. Correia; Pedro de Lima Neto

    2011-01-01

    The modification of a gold electrode surface by electropolymerization of trans-[Ru(NH3)4(Ist)SO4]+ to produce an electrochemical sensor for nitric oxide was investigated. The influence of dopamine, serotonin and nitrite as interferents for NO detection was also examined using square-wave voltammetry (SWV). The characterization of the modified electrode was carried out by cyclic voltammetry, electrochemical quartz crystal microbalance (EQCM) and SERS techniques.

  18. Influence of steps on the electrochemical oxidation of CO adlayers on Pd(111) and on Pd films electrodeposited onto Au(111)

    Microsoft Academic Search

    A. M El-Aziz; L. A Kibler

    2002-01-01

    Electrochemically deposited palladium monolayers on well-ordered and on vicinal Au(111) electrodes have been characterised in sulphuric acid solution by cyclic voltammetry. The electrochemical behaviour of these pseudomorphically grown palladium overlayers is compared with that of a well-ordered and a previously oxidised Pd(111) electrode for hydrogen adsorption, sulphate adsorption as well as for surface oxide formation. A strong impact of the

  19. FY 1992 Annual report: Mediated electrochemical oxidation treatment for Rocky Flats combustible low-level mixed waste. Final report to Rocky Flats Plant

    Microsoft Academic Search

    Z. Chiba; P. R. Lewis; R. W. Kahle

    1993-01-01

    The Mediated Electrochemical Oxidation (MEO) process was studied for destroying low-level combustible mixed wastes at Rocky Flats (RFP). Tests were performed with nonradioactive surrogate materials: Trimsol for the contaminated oils, and reagent-grade cellulose for the cellulosic wastes. Extensive testing was carried out on Trimsol in both small laboratory-scale apparatus and on a large-scale system incorporating an industrial-size electrochemical cell. Preliminary

  20. Kinetic Investigation of the Electrochemical Oxidation of Bis(benzene)chromium(0) in Diethyl ketone\\/N,N-Dimethylformamide

    Microsoft Academic Search

    Nikos G. Tsierkezos

    2008-01-01

    The cyclic voltametric technique utilizing a platinum working electrode was applied for the investigation of the electrochemical\\u000a oxidation of bis(benzene)chromium(0), (C6H6)2Cr to bis(benzene)chromium(I), (C6H6)2Cr+ in diethyl ketone (DEK), N,N-dimethylformamide (DMF), and DEK\\/DMF binary mixtures containing n-tetrabutylammonium hexafluorophosphate (TBAPF6) as the supporting electrolyte at T=298.15 K. The half-wave potentials (E\\u000a 1\\/2) of the (C6H6)2Cr+\\/0 redox couple in DEK, DMF and DEK\\/DMF binary

  1. Electrochemical Characteristics of Lithium Transition-Metal Oxide as an Anode Material in a Lithium Secondary Battery

    Microsoft Academic Search

    Chil-Hoon Doh; Bong-Soo Jin; Jung-Hwan Lim; Seong-In Moon

    2002-01-01

    Lithium transition-metal oxides (LiTMOs) such as LiCoO2 and LiMn2O4 were investigated for their use as anode material for the lithium secondary battery. Ni?Li0?LiPF6(lM, EC + DEC (1 : l))?LiTMO?Cu cell was fabricated and its electrochemical properties were examined. LiCoO2 and LiMn2O4 showed fairly good characteristics as anode material as well as cathode material. At the 1st cathodic process, LiCoO2 had

  2. Electrochemical modification of the passive oxide layer on a Ti film observed by in situ neutron reflectometry

    SciTech Connect

    Tun, Z. [National Research Council, Chalk River, Ontario (Canada). Chalk River Labs.] [National Research Council, Chalk River, Ontario (Canada). Chalk River Labs.; Noeel, J.J.; Shoesmith, D.W. [Atomic Energy of Canada Limited, Pinawa, Manitoba (Canada). Whiteshell Labs.] [Atomic Energy of Canada Limited, Pinawa, Manitoba (Canada). Whiteshell Labs.

    1999-03-01

    Anodization and the effect of subsequently applying cathodic potential to a thin-film Ti electrode in an aqueous NaCl solution have been studied with in situ neutron reflectometry. This new technique provides further insight into the processes underlying anodic oxide formation and hydrogen absorption under cathodic polarization. The results (Pilling-Bedworth ratio, anodization ratio, the onset of fluctuations in electrode current under cathodic potential, etc.) are generally in agreement with the literature, but this new technique provides further insight into the electrochemical processes. The anodized oxide is observed to be not porous, and has the density of the rutile structure for its entire thickness. However, it comprises two distinct regions: an inner region similar in thickness and composition to the original air-grown oxide, and an outer region containing a significant amount of hydrogen. The similarity of the inner region to the original oxide suggests that the underlying oxide growth mechanism for Ti is the point-defect model. Under applied cathodic potentials the overall oxide thickness remains constant, but the inner region is gradually converted to a material similar in hydrogen content to the outer region. The onset of massive hydrogen penetration seems to occur when the conversion is complete, or when the inner region has been reduced to only a few atomic layers.

  3. Electrochemical oxidation of the chalcopyrite surface: an XPS and AFM study in solution at pH 4

    NASA Astrophysics Data System (ADS)

    Farquhar, Morag L.; Wincott, Paul L.; Wogelius, Roy A.; Vaughan, David J.

    2003-09-01

    The electrochemical oxidation of chalcopyrite (CuFeS 2) has been studied at pH 4 using voltammetry, coulometry, X-ray photoelectron spectroscopy (XPS) and both ex situ and in situ atomic force microscopy (AFM). Between 500 and 650 mV an anodic oxidation peak is observed, prior to the onset of the main decomposition reactions. Chalcopyrite electrodes in contact with electrolyte show some release of Cu into solution even without an applied potential. At 500 and 650 mV, the loss of Cu from the surface increases by a factor of 2 and 6, respectively. Oxidation at 500 mV results in the formation of a mixed oxide or hydroxide of iron, coincident with islands (<0.15 ?m wide) of reaction products observed on the surface using AFM. The surface coverage of these islands increases with amount of charge passed. Oxidation at 650 mV shows similar processes have occurred, but with a greater island surface coverage and a more deeply altered surface. XPS depth profiling suggests iron oxide or hydroxide is now a major phase in the top ˜40 Å, with significant sulphate also formed. Observation of islands (alteration products) using in situ AFM under potential control shows that these features are not an artefact of the preparation methods.

  4. Electrochemical oxidation of sulfide ion at a Ti\\/IrO 2 –Ta 2 O 5 anode in the presence and absence of naphthenic acids

    Microsoft Academic Search

    Jamie Haner; Dorin Bejan; Nigel J. Bunce

    2009-01-01

    Electrochemical oxidation of sulfide ion at a Ti\\/IrO2–Ta2O5 anode followed partial order kinetics (between current and mass transport control) in the absence and presence of chloride\\u000a ion and of naphthenic acids, at sulfide concentrations typical of sour brines. The desired outcome was to promote the 2-electron\\u000a oxidation of sulfide to elemental sulfide rather than the 8-electron oxidation to sulfate. Although

  5. Characterizing mechanisms of extracellular electron transport in sulfur and iron-oxidizing electrochemically active bacteria isolated from marine sediments

    NASA Astrophysics Data System (ADS)

    Rowe, A. R.; Bird, L. J.; Lam, B. R.; Nealson, K. H.

    2014-12-01

    Lithotrophic reactions, including the oxidation of mineral species, are often difficult to detect in environmental systems. This could be due to the nature of substrate or metabolite quantification or the rapid consumption of metabolic end products or intermediates by proximate biological or abiotic processes. Though recently genetic markers have been applied to detecting these processes in environmental systems, our knowledge of lithotrophic markers are limited to those processes catalyzed by organisms that have been cultured and physiologically characterized. Here we describe the use of electrochemical enrichment techniques to isolate marine sediment-dwelling microbes capable of the oxidation or insoluble forms of iron and sulfur including both the elemental species. All the organisms isolated fall within the Alphaproteobacteria and Gammaproteobacteria and are capable of acquiring electrons from an electrode while using either oxygen or nitrate as a terminal electron acceptor. Electrochemical analysis of these microbes has demonstrated that, though they have similar geochemical abilities (either sulfur or iron oxidation), they likely utilize different biochemical mechanisms demonstrated by the variability in dominant electron transfer modes or interactions (i.e., biofilm, planktonic or mediator facilitated interactions) and the wide range of midpoint potentials observed for dominant redox active cellular components (ranging from -293 to +50 mV vs. Ag/AgCl). For example, organisms isolated on elemental sulfur tended to have higher midpoint potentials than iron-oxidizing microbes. A variety of techniques are currently being applied to understanding the different mechanisms of extracellular electron transport for oxidizing an electrode or corresponding insoluble electron donor including both genomic and genetic manipulation experiments. The insight gained from these experiments is not limited to the physiology of the organisms isolated but will also aid in identification of genetic targets to better understand the ecologic importance of lithotrophs and the role solid substrates may play in their metabolism.

  6. Enhancing electrochemical performance by control of transport properties in buffer layers - solid oxide fuel/electrolyser cells.

    PubMed

    Ramasamy, Devaraj; Nasani, Narendar; Brandão, Ana D; Pérez Coll, Domingo; Fagg, Duncan P

    2015-04-21

    The current work demonstrates how tailoring the transport properties of thin ceria-based buffer layers in solid oxide fuel or electrolyser cells can provide the necessary phase stability against chemical interaction at the electrolyte/electrode interface, while also providing radical improvements in the electrochemical performance of the oxygen electrode. Half cells of Ce0.8R0.2O2-? + 2 mol% Co buffer layers (where R = Gd, Pr) with Nd2NiO4+? electrodes were fabricated by spin coating on dense YSZ electrolyte supports. Dramatic decreases in polarization resistance, Rp, of up to an order of magnitude, could be achieved in the order, Pr ? Gd < no buffer layer. The current article shows how this improvement can be related to increased levels of ambipolar conductivity in the mixed conducting buffer layer, which provides an additional parallel path for electrochemical reaction. This is an important breakthrough as it shows how electrode polarization resistance can be substantially improved, in otherwise identical electrochemical cells, solely by tailoring the transport properties of thin intermediate buffer layers. PMID:25857870

  7. Nitrogen doped holey graphene as an efficient metal-free multifunctional electrochemical catalyst for hydrazine oxidation and oxygen reduction.

    PubMed

    Yu, Dingshan; Wei, Li; Jiang, Wenchao; Wang, Hong; Sun, Bo; Zhang, Qiang; Goh, Kunli; Si, Rongmei; Chen, Yuan

    2013-04-21

    Electrocatalysts for anode or cathode reactions are at the heart of electrochemical energy conversion and storage devices. Molecular design of carbon based nanomaterials may create the next generation electrochemical catalysts for broad applications. Herein, we present the synthesis of a three-dimensional (3D) nanostructure with a large surface area (784 m(2) g(-1)) composed of nitrogen doped (up to 8.6 at.%) holey graphene. The holey structure of graphene sheets (~25% of surface area is attributed to pores) engenders more exposed catalytic active edge sites. Nitrogen doping further improves catalytic activity, while the formation of the 3D porous nanostructure significantly reduces graphene nanosheet stacking and facilitates the diffusion of reactants/electrolytes. The three factors work together, leading to superb electrochemical catalytic activities for both hydrazine oxidation (its current generation ability is comparable to that of 10 wt% Pt-C catalyst) and oxygen reduction (its limiting current is comparable to that of 20 wt% Pt-C catalyst) with four-electron transfer processes and excellent durability. PMID:23474688

  8. Effects of lead oxide addition on the electrochemical properties of alloy 600 in aqueous 1 M sodium hydroxide solution

    SciTech Connect

    Pyun, S.I.; Lee, W.J.; Park, J.J.

    1999-12-01

    Effects of lead oxide (PbO) addition on the electrochemical properties of alloy 600 (UNS N06600) have been studied in aqueous 1 M sodium hydroxide (NaOH) solution at room temperature using surface analytical techniques and electrochemical methods. For the comparative study on the different roles of the surface layers in the electrochemical properties of alloy 600, two kinds of electrodes were potentiostatically prepared at the anodic and cathodic potential peaks observed in cyclic voltammograms obtained in PbO-containing caustic solution; lead dioxide (PbO{sub 2}) film-covered and Pb deposit-covered alloy electrodes. The crystal structures and morphologies of the two kinds of the surface layers were characterized by x-ray diffractometry and scanning electron microscopy. From the open-circuit potential (OCP) transients and galvanic current transients. It was inferred that Ni and Fe among alloy 600 constituents as anodic sites were dissolved selectively in caustic solution caused by the lower OCP value where there was no PbO{sub 2} alloy. Based upon the experimental results, it was suggested that an enhanced dissolution of Ni and Fe in alloy 600 in caustic solution at room temperature was a consequence of PbO{sub 2}-induced corrosion.

  9. Dyes wastewater treatment by reduction-oxidation process in an electrochemical reactor packed with natural manganese mineral.

    PubMed

    Wang, Ai-Min; Qu, Jiu-Hui; Liu, Hui-Juan; Lei, Peng-Ju

    2006-01-01

    A novel technology which combined electrochemical process catalyzed by manganese mineral with electro-assisted coagulation process was proposed in this study. The mineralization of organic pollutant from simulated dye wastewater containing an azo dye Acid Red B (ARB) was experimentally investigated using this method. It was found that the manganese mineral could catalyze the electrochemical process dramatically. The TOC removal percentage of electrochemical treatment catalyzed by manganese mineral was 43.6% while the TOC removal percentage of the process using the manganese mineral alone and using the electrolysis alone were 9.3% and 20.8%, respectively. Moreover, it was found that combined electroxidation with electro-assisted coagulation process could more effectively eliminate ARB. After a period of 180 min electrooxidation and 300 min electroreduction, almost 66.9% of TOC was removed, and the dissolved Mn2+ could be effectivly removed. The effects of the order of oxidation and reduction, the proper ratio electrooxidation/reduction time, and current density on the removal efficiency were investigated in detail. In addition, a proposed mechanism of manganese-mineral-catalyzed electrooxidation-reduction process was discussed in this paper. PMID:20050542

  10. Electrochemical properties of spinel-type manganese oxide/porous carbon nanocomposite powders in 1 M KOH aqueous solution

    NASA Astrophysics Data System (ADS)

    Tsumura, Tomoki; Tsumori, Koichiro; Shimizu, Goichi; Toyoda, Masahiro

    2012-02-01

    Spinel-type manganese oxide/porous carbon (Mn3O4/C) nanocomposite powders have been simply prepared by a thermal decomposition of manganese gluconate dihydrate under an Ar gas flow at above 600 °C. The structure and texture of the Mn3O4/C nanocomposite powders are investigated by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) equipped scanning transmission electron microscopy (STEM), transmission electron microscopy (TEM), selected area-electron diffraction (SA-ED), thermogravimetric and differential thermal analysis (TG-DTA) and adsorption/desorption of N2 gas at -196 °C. The electrochemical properties of the nanocomposite powders in 1 M KOH aqueous solution are studied, focusing on the relationship between their structures and electrochemical capacitance.In the nanocomposite powders, Mn3O4 nano particles approximately 5 nm in size are dispersed in a porous carbon matrix. The nanocomposite powders prepared at 800 °C exhibit a high specific capacitance calculated from cyclic voltammogram of 350 and 600 F g-1 at a sweep rate of 1 and 0.1 mV s-1, respectively. The influence of the heating temperature on the structure and the electrochemical properties of nanocomposite powders is also discussed.

  11. Allylic ionic liquid electrolyte-assisted electrochemical surface passivation of LiCoO2 for advanced, safe lithium-ion batteries

    PubMed Central

    Mun, Junyoung; Yim, Taeeun; Park, Jang Hoon; Ryu, Ji Heon; Lee, Sang Young; Kim, Young Gyu; Oh, Seung M.

    2014-01-01

    Room-temperature ionic liquid (RTIL) electrolytes have attracted much attention for use in advanced, safe lithium-ion batteries (LIB) owing to their nonvolatility, high conductivity, and great thermal stability. However, LIBs containing RTIL-electrolytes exhibit poor cyclability because electrochemical side reactions cause problematic surface failures of the cathode. Here, we demonstrate that a thin, homogeneous surface film, which is electrochemically generated on LiCoO2 from an RTIL-electrolyte containing an unsaturated substituent on the cation (1-allyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide, AMPip-TFSI), can avert undesired side reactions. The derived surface film comprised of a high amount of organic species from the RTIL cations homogenously covered LiCoO2 with a <25?nm layer and helped suppress unfavorable thermal reactions as well as electrochemical side reactions. The superior performance of the cell containing the AMPip-TFSI electrolyte was further elucidated by surface, electrochemical, and thermal analyses. PMID:25168309

  12. Allylic ionic liquid electrolyte-assisted electrochemical surface passivation of LiCoO2 for advanced, safe lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Mun, Junyoung; Yim, Taeeun; Park, Jang Hoon; Ryu, Ji Heon; Lee, Sang Young; Kim, Young Gyu; Oh, Seung M.

    2014-08-01

    Room-temperature ionic liquid (RTIL) electrolytes have attracted much attention for use in advanced, safe lithium-ion batteries (LIB) owing to their nonvolatility, high conductivity, and great thermal stability. However, LIBs containing RTIL-electrolytes exhibit poor cyclability because electrochemical side reactions cause problematic surface failures of the cathode. Here, we demonstrate that a thin, homogeneous surface film, which is electrochemically generated on LiCoO2 from an RTIL-electrolyte containing an unsaturated substituent on the cation (1-allyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide, AMPip-TFSI), can avert undesired side reactions. The derived surface film comprised of a high amount of organic species from the RTIL cations homogenously covered LiCoO2 with a <25 nm layer and helped suppress unfavorable thermal reactions as well as electrochemical side reactions. The superior performance of the cell containing the AMPip-TFSI electrolyte was further elucidated by surface, electrochemical, and thermal analyses.

  13. Allylic ionic liquid electrolyte-assisted electrochemical surface passivation of LiCoO2 for advanced, safe lithium-ion batteries.

    PubMed

    Mun, Junyoung; Yim, Taeeun; Park, Jang Hoon; Ryu, Ji Heon; Lee, Sang Young; Kim, Young Gyu; Oh, Seung M

    2014-01-01

    Room-temperature ionic liquid (RTIL) electrolytes have attracted much attention for use in advanced, safe lithium-ion batteries (LIB) owing to their nonvolatility, high conductivity, and great thermal stability. However, LIBs containing RTIL-electrolytes exhibit poor cyclability because electrochemical side reactions cause problematic surface failures of the cathode. Here, we demonstrate that a thin, homogeneous surface film, which is electrochemically generated on LiCoO2 from an RTIL-electrolyte containing an unsaturated substituent on the cation (1-allyl-1-methylpiperidinium bis(trifluoromethanesulfonyl)imide, AMPip-TFSI), can avert undesired side reactions. The derived surface film comprised of a high amount of organic species from the RTIL cations homogenously covered LiCoO2 with a <25 nm layer and helped suppress unfavorable thermal reactions as well as electrochemical side reactions. The superior performance of the cell containing the AMPip-TFSI electrolyte was further elucidated by surface, electrochemical, and thermal analyses. PMID:25168309

  14. Advanced oxidation of bleached eucalypt kraft pulp mill effluent.

    PubMed

    Mounteer, A H; Pereira, R O; Morais, A A; Ruas, D B; Silveira, D S A; Viana, D B; Medeiros, R C

    2007-01-01

    In this study a poorly biodegradable (BOD/COD = 0.3) industrial alkaline ECF bleaching filtrate was treated using different advanced oxidation processes to evaluate their use in combined chemical-biological treatment aimed at increasing recalcitrant COD removal and improving final effluent quality. Oxidative treatments included ozonation combined with hydrogen peroxide (2, 5, 10, 20 mmol L(-1) O3/0.7, 2, 5, 10 mmol L(-1) H2O2) and photocatalysis with hydrogen peroxide (UV/2, 4 and 8 mmolL(-1) H2O2) and with TiO2 (UV/TiO2/0.7 and 4 mmol L(-1) H2O2). The O3/H2O2 process increased effluent biodegradability by up to 68% as a result of increasing BOD and decreasing COD. Increasing the O3 dose had a greater effect on biodegradability improvement and lignin and colour removal efficiencies than increasing the H2O2 dose. A combined oxidant dose of 5 mmol L(-1) O3 and 2 mmol L(-1) H2O2 resulted in 75% lignin removal, 40% colour removal and 6% carbohydrate loss without mineralizing the organic carbon. The photocatalytic processes led to a decrease in effluent biodegradability through combined decrease in BOD and increase in COD and did not result in efficient lignin or colour removal. Photocatalytic oxidation was apparently inhibited by the high chloride and COD levels in the alkaline filtrate, and may be more efficient in recalcitrant COD removal if performed after biological. PMID:17486841

  15. Reinforcement of a sugar-based bolaamphiphile/functionalized graphene oxide composite gel: rheological and electrochemical properties.

    PubMed

    Lee, Ji Ha; Ahn, Junho; Masuda, Mitsutoshi; Jaworski, Justyn; Jung, Jong Hwa

    2013-11-01

    A sugar-based bolaamphiphile/graphene oxide composite hydrogel has been prepared using simple mixing. Unlike the corresponding sugar-based native gel, the composite gel exhibits a fibrillar structure with a 10-20 nm fiber diameter. The composite gel forms an interdigitated bilayer structure incorporating intermolecular hydrogen-bonding interactions. The composite gel formation did not change the beneficial electrical properties of graphene offering the potential for integration of this new material into electronic systems. Interestingly, the mechanical and electrochemical properties of the composite gel are both dramatically enhanced when compared to the native gel, thereby reflecting that the functionalized graphene oxide layers are efficiently intercalated within the composite gel structure. PMID:24093646

  16. Review: advances in electrochemical genosensors-based methods for monitoring blooms of toxic algae.

    PubMed

    Orozco, Jahir; Medlin, Linda K

    2013-10-01

    Harmful algal blooms (HABs), which have expanded worldwide in their occurrence and frequency, are a serious menace to aquatic ecosystems and humans. The development of rapid, accurate and cost-effective detection systems for toxic algal monitoring in aquatic environments is urgently required. Although many efforts have been devoted to develop reliable tools to monitor the entire spectrum of existing toxic algae, a portable semi-automated system that enables HAB monitoring at a low cost is still not available for general purchase. This work reviews the challenges and opportunities in translating the remarkable progress of electrochemical genosensors-based methods towards practical in situ HAB monitoring applications. It is specifically focused on reviewing the optimised methods for a detection system based on a sandwich hybridisation assay (SHA) performed over transducer platforms of different materials, geometries and dimensions and presenting the diverse advantages and disadvantages among them. Probe design and specificity and optimisation of the genosensor in terms of hybridisation conditions and electrochemical signal are discussed as well as their long-term stability and storage and semi-automation attempts. With continuous innovation and attention to key challenges, we expect semi-automatic devices containing DNA-based electrochemical biosensors to have an important impact upon monitoring of serious HAB events. PMID:23097073

  17. Evaluation of an Oxide Layer on NI-CR-MO-W Alloy Using Electrochemical Impedance Spectroscopy and Surface Analysis

    SciTech Connect

    D. Zagidulin; P. Jakupi; J.J. Noel; D.W. Shoesmith

    2006-12-21

    High corrosion resistance under very aggressive conditions is a distinguishing property of Ni-Cr-Mo-W alloys. One such alloy, Alloy 22, is a candidate material for fabrication of the outer layer of high-level nuclear waste (HLNW) packages for the proposed HLNW repository at Yucca Mountain, Nevada, USA. We are using Electrochemical Impedance Spectroscopy (EIS), ex-situ X-Ray Photoelectron Spectroscopy (XPS) and Time of Flight Secondary Ion Mass Spectroscopy (ToF SIMS) to characterize the electrochemical properties and composition of the protective oxide formed on Alloy 22 surfaces. These studies have been conducted at temperatures up to 90 C at potentials from -0.8 V to 0.8 V (vs. Ag/AgCl (sat'd KCl)) in deaerated 5 mol L{sup -1} NaCl solution. Using this combination of techniques, we can correlate the electrical (from EIS) and compositional properties (from XPS, ToF SIMS) of the oxide. At more negative potentials (-0.8 V to -0.4 V) the film exhibits a low charge transfer resistance and high capacitance, indicating the presence of a very defective film with a high concentration of electronic defects. The presence of additional elements in the equivalent circuit, corresponding to water reduction, supports this suggestion. At these potentials, surface analysis techniques show a thin oxide layer with a low concentration of Cr203. Increasing the potential (to between -0.2 and 0.2 V) leads to a major increase in overall interfacial resistance consistent with the formation of an oxide with a small concentration of electronic defects. At the same time, the surface analysis techniques show increases in the film thickness and the Cr{sub 2}O{sub 3} content. A further increase in potential to 0.8 V, in general, leads to a decrease in interfacial resistance throughout the film. When the Cr{sub 2}O{sub 3} barrier layer is degraded, then the higher oxidation states of Mo and W species (MO{sup VI}, W{sup VI}) increase in concentration and are stored in the outer part of the film (at temperatures up to 60 C). The storage of these high oxidation state ions generates a high interfacial capacitance. At high temperature (above 60 C), the XPS and EIS show that the high oxidation states of Mo and W are absent. We think this is because they dissolve from the oxide under those conditions.

  18. Polyaniline-iron oxide nanohybrid film as multi-functional label-free electrochemical and biomagnetic sensor for catechol.

    PubMed

    Chandra, Sudeshna; Lang, Heinrich; Bahadur, Dhirendra

    2013-09-17

    Polyaniline-iron oxide magnetic nanohybrid was synthesized and characterized using various spectroscopic, microstructural and electrochemical techniques. The smart integration of Fe3O4 nanoparticles within the polyaniline (PANI) matrix yielded a mesoporous nanohybrid (Fe3O4@PANI) with high surface area (94 m(2) g(-1)) and average pore width of 12.8 nm. Catechol is quasi-reversibly oxidized to o-quinone and reduced at the Fe3O4@PANI modified electrodes. The amperometric current response toward catechol was evaluated using the nanohybrid and the sensitivity and detection limit were found to be 312 ?A ?L(-1) and 0.2 nM, respectively. The results from electrochemical impedance spectroscopy (EIS) indicated that the increased solution resistance (Rs) was due to elevated adsorption of catechol on the modified electrodes. Photoluminescence spectra showed ligand-to-metal charge transfer (LMCT) between p-? orbitals of the phenolate oxygen in catechol and the d-?* metal orbital of Fe3O4@PANI nanohybrid. Potential dependent spectroelectrochemical behavior of Fe3O4@PANI nanohybrid toward catechol was studied using UV/vis/NIR spectroscopy. The binding activity of the biomagnetic particles to catechol through Brownian relaxation was evident from AC susceptibility measurements. The proposed sensor was used for successful recovery of catechol in tap water samples. PMID:23998532

  19. The effect of As, Co, and Ni impurities on pyrite oxidation kinetics: An electrochemical study of synthetic pyrite

    NASA Astrophysics Data System (ADS)

    Lehner, Stephen; Savage, Kaye; Ciobanu, Madalina; Cliffel, David E.

    2007-05-01

    Synthetic pyrite crystals doped with As, Co, or Ni, undoped pyrite, and natural arsenian pyrite from Leadville, Colorado were investigated with electrochemical techniques and solid-state measurements of semiconducting properties to determine the effect of impurity content on pyrite's oxidation behavior. Potential step experiments, cyclic voltammetry, and AC voltammetry were performed in a standard three-electrode electrochemical cell setup. A pH 1.78 sulfuric acid solution containing 1 mM ferric iron, open to atmospheric oxygen, was chosen to approximate water affected by acid drainage. Van der Pauw/Hall effect measurements determined resistivity, carrier concentration and carrier mobility. The anodic dissolution of pyrite and the reduction of ferric iron half-reactions are taken as proxies for natural pyrite oxidation. Pyrite containing no impurities is least reactive. Pyrite with As is more reactive than pyrite with either Ni or Co despite lower dopant concentration. As, Co, and Ni impurities introduce bulk defect states at different energy levels within the band gap. Higher reactivity of impure pyrite suggests that introduced defect levels lead to higher density of occupied surface states at the solid-solution interface and increased metallic behavior. The current density generated from potential step experiments increased with increasing As concentration. The higher reactivity of As-doped pyrite may be related to p-type conductivity and corrosion by holes. The results of this study suggest that considering the impurity content of pyrite in mining waste may lead to more accurate risk assessment of acid producing potential.

  20. Nanostructures and Lithium Electrochemical Reactivity of Lithium Titanites and Titanium Oxides: A Review

    SciTech Connect

    Yang, Zhenguo; Choi, Daiwon; Kerisit, Sebastien N.; Rosso, Kevin M.; Wang, Donghai; Zhang, Jiguang; Graff, Gordon L.; Liu, J.

    2009-07-15

    Being inherently safe and chemically compatible with the electrolyte, titanium oxidebased materials, including both Li-titanites and various TiO2-polymorphs, are considered alternatives to carbonaceous anodes in Li-ion batteries. Given the commercial success of the spinel lithium titanites, TiO2-polymorphs, in particular in nanostructured forms, have been fabricated and investigated for the applications. Nanostructuring leads to increased reaction areas, shortened Li+ diffusion and potentially enhanced solubility/capacity. Integration with an electron conductive second phase into the TiO2-based nanostructures eases the electron transport, resulting in further improved lithium electrochemical activity and the overall electrochemical performance. This paper reviews structural characteristics and Li-electrochemical reactivity, along with synthetic approaches, of nanostructures and nano-composites based on lithium titanites and TiO2-polymorphs that include rutile, anatase, bronze and brookite.

  1. Analysis of advanced oxidation processes in a hybrid air pollution control system, 1996

    Microsoft Academic Search

    B. A. Striebig; J. M. Schneider; T. A. Spaeder; M. R. Mallery; R. J. Heinsohn

    1996-01-01

    With the passage of the 1990 Clean Air Act, advanced oxidation processes have gained interest as an alternative for treating a variety of industrial air and waste water streams. These advanced oxidation processes are very attractive when contaminant compositions and concentrations in the air stream vary widely making typical catalytic incineration costly in terms of fuel and potential catalyst fouling.

  2. Electrochemical degradation of polycyclic aromatic hydrocarbons in creosote solution using ruthenium oxide on titanium expanded mesh anode.

    PubMed

    Tran, Lan-Huong; Drogui, Patrick; Mercier, Guy; Blais, Jean-François

    2009-05-30

    In this study, expanded titanium (Ti) covered with ruthenium oxide (RuO(2)) electrode was used to anodically oxidize polycyclic aromatic hydrocarbons (PAH) in creosote solution. Synthetic creosote-oily solution (COS) was prepared with distilled water and a commercial creosote solution in the presence of an amphoteric surfactant; Cocamidopropylhydroxysultaine (CAS). Electrolysis was carried out using a parallelepipedic electrolytic 1.5-L cell containing five anodes (Ti/RuO(2)) and five cathodes (stainless steel, 316 L) alternated in the electrode pack. The effects of initial pH, temperature, retention time, supporting electrolyte, current density and initial PAH concentration on the process performance were examined. Experimental results revealed that a current density of 9.23 mA cm(-2) was beneficial for PAH oxidation. The sum of PAH concentrations for 16 PAHs could be optimally diminished up to 80-82% while imposing a residence time in the electrolysis cell of 90 min. There was not a significant effect of the electrolyte (Na(2)SO(4)) concentration on oxidation efficiency in the investigated range of 500-4000 mg/L. However, an addition of 500 mg Na(2)SO(4)L(-1) was required to reduce the energy consumption and the treatment cost. Besides, there was no effect of initial PAH concentration on oxidation efficiency in the investigated range of 270-540 mg PAHL(-1). Alkaline media was not favourable for PAH oxidation, whereas high performance of PAH degradation could be recorded without initial pH adjustment (original pH around 6.0). Likewise, under optimal conditions, 84% of petroleum hydrocarbon (C(10)-C(50)) was removed, whereas removal yields of 69% and 62% have been measured for O&G and COD, respectively. Microtox and Daphnia biotests showed that electrochemical oxidation using Ti/RuO(2) could be efficiently used to reduce more than 90% of the COS toxicity. PMID:18926633

  3. Structural and electrochemical characterization of two proton conducting oxide thin films for a microfabricated solid oxide fuel cell

    E-print Network

    Capozzoli, Peter M

    2006-01-01

    The use of proton conducting oxide materials as an electrolyte offers the potential to reduce the operating temperature of a solid oxide fuel cell (SOFC), leading to improved thermal management and material compatibility. ...

  4. Amperometric detection and electrochemical oxidation of aliphatic amines and ammonia on silver-lead oxide thin-film electrodes

    SciTech Connect

    Ge, Jisheng

    1996-01-08

    This thesis comprises three parts: Electrocatalysis of anodic oxygen-transfer reactions: aliphatic amines at mixed Ag-Pb oxide thin-film electrodes; oxidation of ammonia at anodized Ag-Pb eutectic alloy electrodes; and temperature effects on oxidation of ethylamine, alanine, and aquated ammonia.

  5. Electrochemical characteristics of calcium in organic electrolyte solutions and vanadium oxides as calcium hosts

    Microsoft Academic Search

    M. Hayashi; H. Arai; H. Ohtsuka; Y. Sakurai

    2003-01-01

    We investigated batteries using calcium as the transfer ion with a view to developing high energy density and safe ion-transfer type batteries as an alternative to lithium-ion batteries. The electrochemical behavior of calcium electrodes in various kinds of electrolyte solution was investigated by means of galvanostatic measurements. The anodic dissolution proceeded easily, but there was no cathodic deposition in the

  6. Preparation and characterization of cobalt oxide nanosized particles obtained by an electrochemical method

    Microsoft Academic Search

    E. P. Reddy; T. C. Rojas; J. C. Sánchez-López; M. Domínguez; E. Roldán; J. Cámpora; P. Palma; A. Fernández

    1999-01-01

    An electrochemical process has been described by which metal foils are anodically dissolved and the metal salts formed as intermediates are cathodically reduced with formation of metal clusters stabilized by tetraalkylammonium salts. The electrolysis process has been investigated by cyclic voltammetry showing the formation of reduced cobalt adatoms followed by cluster formation. In the present paper we have studied such

  7. Degradative Oxidation of 2,4,6 Trichlorophenol Using Advanced Oxidation Processes – A Comparative Study

    Microsoft Academic Search

    P. Saritha; D. Samuel Suman Raj; C. Aparna; P. Nalini Vijaya Laxmi; V. Himabindu; Y. Anjaneyulu

    2009-01-01

    In the present study, a comparative assessment of 2,4,6-T (2,4,6-Trichlorophenol) degradation by different AOPs (Advanced\\u000a Oxidation Processes – UV, UV\\/ H2O2, Fenton, UV\\/Fenton and UV\\/TiO2) in the laboratory scale is performed. The effects of different reactant concentrations and pH are assessed. 2,4,6-T removal,\\u000a Total Organic Carbon mineralization (TOC) and dechlorination are monitored. Of all the AOPs, UV\\/Fenton process is more

  8. Simultaneous electrochemical determination of dopamine and paracetamol on multiwalled carbon nanotubes/graphene oxide nanocomposite-modified glassy carbon electrode.

    PubMed

    Cheemalapati, Srikanth; Palanisamy, Selvakumar; Mani, Veerappan; Chen, Shen-Ming

    2013-12-15

    In the present study, multiwalled carbon nanotubes (MWCNT)/graphene oxide (GO) nanocomposite was prepared by homogenous dispersion of MWCNT and GO and used for the simultaneous voltammetric determination of dopamine (DA) and paracetamol (PA). The TEM results confirmed that MWCNT walls were wrapped well with GO sheets. The MWCNT/GO nanocomposite showed superior electrocatalytic activity towards the oxidation of DA and PA, when compared with either pristine MWCNT or GO. The major reason for the efficient simultaneous detection of DA and PA at nanocomposite was the synergistic effect between MWCNT and GO. The electrochemical oxidation of DA and PA was investigated by cyclic voltammetry, differential pulse voltammetry and amperometry. The nanocomposite modified electrode showed electrocatalytic oxidation of DA and PA in the linear response range from 0.2 to 400 µmol L(-1) and 0.5 to 400 µmol L(-1) with the detection limit of 22 nmol L(-1) and 47 nmol L(-1) respectively. The proposed sensor displayed good selectivity, sensitivity, stability with appreciable consistency and precision. PMID:24209344

  9. Experimental Approach to Controllably Vary Protein Oxidation While Minimizing Electrode Adsorption for Boron-Doped Diamond Electrochemical Surface Mapping Applications

    SciTech Connect

    McClintock, Carlee [ORNL; Hettich, Robert {Bob} L [ORNL

    2013-01-01

    Oxidative protein surface mapping has become a powerful approach for measuring the solvent accessibility of folded protein structures. A variety of techniques exist for generating the key reagent hydroxyl radicals for these measurements; however, many of these approaches require use of radioactive sources or caustic oxidizing chemicals. The purpose of this research was to evaluate and optimize the use of boron-doped diamond (BDD) electrochemistry as a highly accessible tool for producing hydroxyl radicals as a means to induce a controllable level of oxidation on a range of intact proteins. These experiments utilize a relatively high flow rates to reduce protein residence time inside the electrochemical flow chamber, along with a unique cell activation approach to improve control over the intact protein oxidation yield. Studies were conducted to evaluate the level of protein adsorption onto the electrode surface. This report demonstrates a robust protocol for the use of BDD electrochemistry and high performance LC-MS/MS as a high-throughput experimental pipeline for probing higher order protein structure, and illustrates how it is complementary to predictive computational modeling efforts.

  10. The mechanical, electrochemical, and morphological characteristics of passivating oxide films covering cobalt-chromium-molybdenum alloys: A study of five microstructures

    NASA Astrophysics Data System (ADS)

    Megremis, Spiro John

    2001-07-01

    Cobalt-chromium-molybdenum (Co-Cr-Mo) alloys possess a combination of properties that make them well suited for employment as biomaterials, such as high-strength and excellent wear and corrosion resistance. They receive this excellent corrosion resistance from passive oxide films which cover their surface. Because of the important role these oxide films play in protecting Co-Cr Mo alloys used in biological applications, there is a need to better understand them. This thesis investigated the structural and physical properties of the passivating oxide films covering Co-Cr Mo alloys with five different microstructures. The Co-Cr-Mo alloys were separated into the following groups: cast, wrought high carbon, wrought high carbon aged, forged high carbon, and forged low carbon. Electrochemical scratch tests were performed which provided information on the electrochemical kinetics of oxide fracture and repassivation for the different Co-Cr-Mo alloys. Furthermore, the stability and mechanical integrity of the oxide films covering the alloys were also evaluated. Step-polarization impedance spectroscopy tests were also performed on the different Co-Cr-Mo alloys, which provided valuable information about their electrochemical behavior when immersed in phosphate buffered saline (PBS) solution. For instance, it was observed that the corrosion properties of the different alloy types did not vary significantly with respect to the behavior of their individual polarization curves. Likewise, impedance values (maximum early resistance, maximum polarization resistance, and minimum capacitance) for the five alloy groups did not reveal any statistically meaningful differences. The similar passive electrochemical behavior of the five alloy groups suggests that the oxide films covering them were not significantly altered by changes in carbon content and processing. This research also showed that it was possible to monitor changes in the surface morphology of the cast Co-Cr-Mo alloys over a wide range of potentials using in-situ electrochemical atomic force microscopy. In addition, the collection of SPIS information in conjunction with the AFM images revealed several distinct relationships between surface morphology and electrochemical behavior for the alloys. Thus, it was demonstrated that the combination of electrochemical atomic force microscopy with simultaneous SPIS allowed careful, direct correlation of surface structure and electrochemical properties.

  11. COMPARISON OF ADVANCED OXIDATION PROCESSES FOR THE DESTRUCTION OF 2,4DINITROPHENOL

    Microsoft Academic Search

    Anna GOI; Marina TRAPIDO

    2001-01-01

    Several advanced oxidation processes such as hydrogen peroxide photolysis, the Fenton treatment, photo-Fenton treatment, and ozonation combined with hydrogen peroxide and UV- radiation for the destruction of 2,4-dinitrophenol were studied. Advanced oxidation processes, especially the Fenton treatment, were found to be effective for the degradation of 2,4-dinitrophenol and removal of toxicity. According to the Daphnia magna acute toxicity test, advanced

  12. Advanced Surface Modification of Indium Tin Oxide for Improved Charge Injection in Organic Devices

    E-print Network

    Schwartz, Jeffrey

    Advanced Surface Modification of Indium Tin Oxide for Improved Charge Injection in Organic Devices and involves sequential formation of a monolayer of a -conjugated organic semiconductor on the indium tin oxide, indium tin oxide, ITO) and cathode of organic light emitting diodes (OLEDs), or at electrodes in other

  13. Chapter 8 TiO 2Based Advanced Oxidation Nanotechnologies for Water Purification and Reuse

    Microsoft Academic Search

    Hyeok Choi; Souhail R. Al-Abed; Dionysios D. Dionysiou; Elias Stathatos; Panagiotis Lianos

    2010-01-01

    Advanced oxidation technologies (AOTs) produce highly reactive radical species, which readily attack and decompose organic pollutants in water eventually mineralizing them to water, carbon dioxide, and other simple inorganic species. AOTs involve nonselective oxidizing species and are among the most efficient chemical oxidation processes for the treatment of water contaminated with biologically toxic and nondegradable chemicals. Among such technologies, TiO2

  14. Chip-based generation of carbon nanodots via electrochemical oxidation of screen printed carbon electrodes and the applications for efficient cell imaging and electrochemiluminescence enhancement.

    PubMed

    Xu, Yuanhong; Liu, Jingquan; Zhang, Jizhen; Zong, Xidan; Jia, Xiaofang; Li, Dan; Wang, Erkang

    2015-06-01

    A portable lab-on-a-chip methodology to generate ionic liquid-functionalized carbon nanodots (CNDs) was developed via electrochemical oxidation of screen printed carbon electrodes. The CNDs can be successfully applied for efficient cell imaging and solid-state electrochemiluminescence sensor fabrication on the paper-based chips. PMID:25959400

  15. Excellent electrochemical properties of yolk-shell MoO? microspheres formed by combustion of molybdenum oxide-carbon composite microspheres.

    PubMed

    Ko, You Na; Park, Seung Bin; Kang, Yun Chan

    2014-04-01

    Yolk-shell MoO3 microspheres are prepared by a two-step process in which molybdenum oxide-carbon (MoO(x)-C) composite microspheres are first obtained by spray pyrolysis, followed by combustion at 400?°C in air. The yolk-shell microspheres exhibit excellent electrochemical properties and structural stability. PMID:24519906

  16. Thermal-fluid and electrochemical modeling and performance study of a planar solid oxide electrolysis cell : analysis on SOEC resistances, size, and inlet flow conditions

    Microsoft Academic Search

    B. Yildiz; J. Smith; T. Sofu

    2008-01-01

    Argonne National Laboratory and Idaho National Laboratory researchers are analyzing the electrochemical and thermal-fluid behavior of solid oxide electrolysis cells (SOECs) for high temperature steam electrolysis using computational fluid dynamics (CFD) techniques. The major challenges facing commercialization of steam electrolysis technology are related to efficiency, cost, and durability of the SOECs. The goal of this effort is to guide the

  17. Investigation of the anodic oxide layer on 1050 and 2024T3 aluminium alloys by electron microscopy and electrochemical impedance spectroscopy

    Microsoft Academic Search

    J.-P Dasquet; D Caillard; E Conforto; J.-P Bonino; R Bes

    2000-01-01

    Transmission and scanning electron microscopy and electrochemical impedance spectroscopy measurements were made on anodic layers on 1050 and 2024T3 aluminium alloys, prepared from solutions of phosphoric acid, boric acid and sodium tetraborate. The microstructural parameters were dependent on the aluminium substrate and the type of electrolyte. A structural model for the oxide layer was generated from the data in the

  18. Effects of synthetic parameters on structure and electrochemical performance of spinel lithium manganese oxide by citric acid-assisted sol–gel method

    Microsoft Academic Search

    Tingfeng Yi; Changsong Dai; Kun Gao; Xinguo Hu

    2006-01-01

    The spinel lithium manganese oxide cathode materials were prepared by citric acid-assisted sol–gel method at 623–1073K in air. The effects of pH value, raw material, synthesis temperature and time on structure and electrochemical performance of spinel lithium manganese oxide are investigated by X-ray diffraction (XRD), scanning electronic microscope (SEM) and cyclic voltammetry (CV). XRD data results strongly suggest that the

  19. Synthesis, characterization, and electrochemical properties of ordered mesoporous carbons containing nickel oxide nanoparticles using sucrose and nickel acetate in a silica template

    SciTech Connect

    Cao Yulin [Nanomaterials Research Institute, College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Cao Jieming [Nanomaterials Research Institute, College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)], E-mail: jmcao@nuaa.edu.cn; Zheng Mingbo [Nanomaterials Research Institute, College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Liu Jinsong [Nanomaterials Research Institute, College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Ji Guangbin [Nanomaterials Research Institute, College of Material Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China)

    2007-02-15

    New ordered mesoporous carbons containing nickel oxide nanoparticles have been successfully synthesized by carbonization of sucrose in the presence of nickel acetate inside SBA-15 mesoporous silica template. The obtained samples were characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, and transmission electron microscopy (TEM). The NiO nanoparticles were embedded inside the mesoporous carbon framework due to the simultaneous pyrolysis of nickel acetate during carbonization. The electrochemical testing of the as-made nanocomposites showed a large specific capacitance of 230 F g{sup -1} using 2 M KOH as the electrolyte at room temperature. This is attributed to the nanometer-sized NiO formed inside mesoporous carbons and the high surface area of the mesopores in which the NiO nanoparticles are formed. Furthermore, the synthetic process is proposed as a simple and general method for the preparation of new functionalized mesoporous carbon materials, for various applications in catalysis, sensor or advanced electrode material. - Graphical abstract: Schematic drawings of synthesis routes for the NiOCMK materials.

  20. Validation of an electrochemical model for the oxidative dissolution of used CANDU fuel

    Microsoft Academic Search

    D. W Shoesmith; S Sunder; J. C Tait

    1998-01-01

    Measured dissolution rates of UO2 and used fuel powders are compared to dissolution rates predicted from electrochemical measurements on fuel pellets. This comparison was made for rates as a function of dissolved oxygen concentration, carbonate\\/bicarbonate concentration, and gamma irradiation dose rate. Measurements were also made as a function of temperature over the range 25–75°C. Good agreement was obtained between measured

  1. Enhanced Yields of Iron-Oxidizing Bacteria by In Situ Electrochemical Reduction of Soluble Iron in the Growth Medium

    PubMed Central

    Blake, Robert C.; Howard, Gary T.; McGinness, Stephen

    1994-01-01

    An electrochemical apparatus for culturing chemolithotrophic bacteria that respire aerobically on ferrous ions is described. Enhanced yields of the bacteria were achieved by the in situ electrochemical reduction of soluble iron in the growth medium. When subjected to a direct current of 30 A for 60 days, a 45-liter culture of Thiobacillus ferrooxidans grew from 6 × 107 to 9.5 × 109 cells per ml. Growth of the bacterium within the electrolytic bioreactor was linear with time. A final cell density corresponding to 4.7 g of wet cell paste per liter was achieved, and a total of 320 g of wet cell paste was harvested from one culture. The apparatus was designed to deliver protons concomitantly with electrons; therefore, the pH of the culture remained stable at 1.6 ± 0.1 for the duration of growth. This laboratory-scale apparatus may be readily adapted to pilot or production scale. It is thus anticipated that abundant numbers of iron-oxidizing bacteria may be obtained for both fundamental and applied studies. PMID:16349344

  2. Electrochemical oxidation of recalcitrant organic compounds in biologically treated municipal solid waste leachate in a flow reactor.

    PubMed

    Quan, Xuejun; Cheng, Zhiliang; Chen, Bo; Zhu, Xincai

    2013-10-01

    Biologically-treated municipal solid waste (MSW) leachate still contains many kinds of bio-recalcitrant organic matter. A new plate and frame electrochemical reactor was designed to treat these materials under flow conditions. In the electrochemical oxidation process, NH3 and color could be easily removed by means of electro-generated chlorine/hypochlorite within 20 min. The effects of major process parameters on the removal of organic pollutants were investigated systematically. Under experimental conditions, the optimum operation parameters were current density of 65 mA/cm2, flow velocity of 2.6 cm/sec in electrode gap, and initial chloride ion concentration of 5000 mg/L. The COD in the leachate could be reduced below 100 mg/L after 1 hr of treatment. The kinetics and mechanism of COD removal were investigated by simultaneously monitoring the COD change and chlorine/hypochlorite production. The kinetics of COD removal exhibited a two-stage kinetic model, and the decrease of electro-generated chlorine/hypochlorite production was the major mechanism for the slowing down of the COD removal rate in the second stage. The narrowing of the electrode gap is beneficial for COD removal and energy consumption. PMID:24494488

  3. The utilization of SiNWs/AuNPs-modified indium tin oxide (ITO) in fabrication of electrochemical DNA sensor.

    PubMed

    Rashid, Jahwarhar Izuan Abdul; Yusof, Nor Azah; Abdullah, Jaafar; Hashim, Uda; Hajian, Reza

    2014-12-01

    This work describes the incorporation of SiNWs/AuNPs composite as a sensing material for DNA detection on indium tin-oxide (ITO) coated glass slide. The morphology of SiNWs/AuNPs composite as the modifier layer on ITO was studied by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The morphological studies clearly showed that SiNWs were successfully decorated with 20 nm-AuNPs using self-assembly monolayer (SAM) technique. The effective surface area for SiNWs/AuNPs-modified ITO enhanced about 10 times compared with bare ITO electrode. SiNWs/AuNPs nanocomposite was further explored as a matrix for DNA probe immobilization in detection of dengue virus as a bio-sensing model to evaluate its performance in electrochemical sensors. The hybridization of complementary DNA was monitored by differential pulse voltammetry (DPV) using methylene blue (MB) as the redox indicator. The fabricated biosensor was able to discriminate significantly complementary, non-complementary and single-base mismatch oligonucleotides. The electrochemical biosensor was sensitive to target DNA related to dengue virus in the range of 9.0-178.0 ng/ml with detection limit of 3.5 ng/ml. In addition, SiNWs/AuNPs-modified ITO, regenerated up to 8 times and its stability was up to 10 weeks at 4°C in silica gel. PMID:25491829

  4. Continuous electrochemical monitoring of nitric oxide production in murine macrophage cell line RAW 264.7.

    PubMed

    Pekarova, Michaela; Kralova, Jana; Kubala, Lukas; Ciz, Milan; Lojek, Antonin; Gregor, Cenek; Hrbac, Jan

    2009-07-01

    In this study, we realized the continual and long-term electrochemical detection of NO production by stimulated macrophages using modified porphyrinic microsensor. The NO release from RAW 264.7 cells stimulated by lipopolysaccharide started 5 h after the lipopolysaccharide administration. After reaching its maximum at the sixth hour, the stable level of NO production was observed between the seventh and 12th hour of the experiment. This phase was followed by a gradual decline in NO production. A close correlation between the NO signal detected with microelectrode and nitrite accumulation, which had been determined in supernatants removed from stimulated cells, was observed. This finding was utilized for the calibration of the electrochemical experiment. The presence of iNOS enzyme, which constitutes a main requirement for NO production by stimulated macrophages, was confirmed by Western blot analysis of iNOS protein expression at key time points of the corresponding electrochemical experiment. The capability of our microsensor to instantaneously monitor the changes in the NO production by stimulated RAW 264.7 cells was demonstrated by the immediate decrease in the signal due to NO as a response to the addition of iNOS inhibitor into the cell culture medium. PMID:19430767

  5. Lithium intercalation in sputter deposited antimony-doped tin oxide thin films: Evidence from electrochemical and optical measurements

    NASA Astrophysics Data System (ADS)

    Montero, J.; Guillén, C.; Granqvist, C. G.; Herrero, J.; Niklasson, G. A.

    2014-04-01

    Transparent conducting oxides are used as transparent electrical contacts in a variety of applications, including in electrochromic smart windows. In the present work, we performed a study of transparent conducting antimony-doped tin oxide (ATO) thin films by chronopotentiometry in a Li+-containing electrolyte. The open circuit potential vs. Li was used to investigate ATO band lineups, such as those of the Fermi level and the ionization potential, as well as the dependence of these lineups on the preparation conditions for ATO. Evidence was found for Li+ intercalation when a current pulse was set in a way so as to drive ions from the electrolyte into the ATO lattice. Galvanostatic intermittent titration was then applied to determine the lithium diffusion coefficient within the ATO lattice. The electrochemical density of states of the conducting oxide was studied by means of the transient voltage recorded during the chronopotentiometry experiments. These measurements were possible because, as Li+ intercalation took place, charge compensating electrons filled the lowest part of the conduction band in ATO. Furthermore, the charge insertion modified the optical properties of ATO according to the Drude model.

  6. Electrochemical Insights on the Hydrophobicity of Cellulose Substrates Imparted by Enzymatically Oxidized Gallates with Increasing Alkyl Chain Length.

    PubMed

    Cusola, Oriol; Valls, Cristina; Vidal, Teresa; Tzanov, Tzanko; Roncero, M Blanca

    2015-07-01

    In this work, we studied the influence of the alkyl chain length in enzymatically oxidized gallates on the development of hydrophobicity on paper-based materials, and further correlated the obtained effect to the redox mechanism of the enzymatic treatment. Laccase (Lac) enzyme was used to oxidize various members of the gallate homologous series in the presence or not of lignosulfonates (SL) to produce several functionalization solutions (FS), which were subsequently applied to cellulosic substrates. The hydrophobicity of the substrates was then assessed by means of water drop test (WDT) and contact angle (WCA) measurements. Hydrophobicity peaked reaching WDT and WCA values around 5000 s and 130°, respectively, and then decreased with increasing length of the hydrocarbon chain of gallate. Cyclic voltrammetry (CV) was used to study the effect of SL on the redox reactions of several gallates. The intensity of the anodic peak in their voltammograms decreased increasing the chain length of the gallate. The electrochemical behavior of lauryl gallate (LG) differed from that of other gallates. The fact that the voltammetric curves for SL and LG intersected at a potential of 478 mV indicates an enhancing effect of SL on LG oxidation at high potentials (above 478 mV). PMID:26057550

  7. Lithium intercalation in sputter deposited antimony-doped tin oxide thin films: Evidence from electrochemical and optical measurements

    SciTech Connect

    Montero, J., E-mail: jose.montero@angstrom.uu.se; Granqvist, C. G.; Niklasson, G. A. [Department of Engineering Sciences, The A°ngström Laboratory, Uppsala University, P.O. Box 534, SE-751 21 Uppsala (Sweden); Guillén, C.; Herrero, J. [Department of Energy, Ciemat, Avda. Complutense 40, Ed. 42, E-28040 Madrid (Spain)

    2014-04-21

    Transparent conducting oxides are used as transparent electrical contacts in a variety of applications, including in electrochromic smart windows. In the present work, we performed a study of transparent conducting antimony-doped tin oxide (ATO) thin films by chronopotentiometry in a Li{sup +}-containing electrolyte. The open circuit potential vs. Li was used to investigate ATO band lineups, such as those of the Fermi level and the ionization potential, as well as the dependence of these lineups on the preparation conditions for ATO. Evidence was found for Li{sup +} intercalation when a current pulse was set in a way so as to drive ions from the electrolyte into the ATO lattice. Galvanostatic intermittent titration was then applied to determine the lithium diffusion coefficient within the ATO lattice. The electrochemical density of states of the conducting oxide was studied by means of the transient voltage recorded during the chronopotentiometry experiments. These measurements were possible because, as Li{sup +} intercalation took place, charge compensating electrons filled the lowest part of the conduction band in ATO. Furthermore, the charge insertion modified the optical properties of ATO according to the Drude model.

  8. An ozone\\/hydrogen peroxide\\/microwave-enhanced advanced oxidation process for sewage sludge treatment

    Microsoft Academic Search

    Guiqing Yin; Ping Huang Liao; Kwang Victor Lo

    2007-01-01

    Solids destruction and nutrients release from sewage sludge were investigated using thermal destruction and\\/or oxidation processes. Hydrogen peroxide (H2O2), ozone (O3) and a combination of both were used for the oxidation processes performed at ambient temperature. Thermal destruction using microwave (MW) alone without an oxidant was also conducted. Microwave enhanced advanced oxidation processes (MW-AOP), such as MW\\/O3, MW\\/H2O2 and MW\\/H2O2\\/O3,

  9. The electrochemical oxidation of troxerutin and its sensitive determination in pharmaceutical dosage forms at PVP modified carbon paste electrode.

    PubMed

    Yang, Xiaofeng; Wang, Fang; Hu, Shengshui

    2006-09-01

    The voltammetric responses of troxerutin were investigated at polyvinylpyrrolidone (cross-linked) (PVP) modified carbon paste electrode (CPE) in 0.1 mol/L KCl by several electrochemical techniques. A well-defined oxidation peak was observed at about 0.97 V. Compared with poor responses of troxerutin at bare electrode that at this modified electrode has been greatly improved. It is PVP that enhances the adsorption of troxerutin to electrode surface based on their hydrophobic property. Under some optimized experimental conditions, a simple and sensitive electroanalytical method was developed for the quantitative analysis of troxerutin. A very low detection limit of 5.0 x 10(-9)mol/L was obtained for 5 min accumulation at open circuit (S/N=3). This proposed method was successfully applied to the detection of troxerutin in pharmaceutical dosage forms and satisfying results had been obtained. PMID:16837175

  10. A bipolar electrochemical approach to constructive lithography: metal/monolayer patterns via consecutive site-defined oxidation and reduction.

    PubMed

    Zeira, Assaf; Berson, Jonathan; Feldman, Isai; Maoz, Rivka; Sagiv, Jacob

    2011-07-01

    Experimental evidence is presented, demonstrating the feasibility of a surface-patterning strategy that allows stepwise electrochemical generation and subsequent in situ metallization of patterns of carboxylic acid functions on the outer surfaces of highly ordered OTS monolayers assembled on silicon or on a flexible polymeric substrate. The patterning process can be implemented serially with scanning probes, which is shown to allow nanoscale patterning, or in a parallel stamping configuration here demonstrated on micrometric length scales with granular metal film stamps sandwiched between two monolayer-coated substrates. The metal film, consisting of silver deposited by evaporation through a patterned contact mask on the surface of one of the organic monolayers, functions as both a cathode in the printing of the monolayer patterns and an anodic source of metal in their subsequent metallization. An ultrathin water layer adsorbed on the metal grains by capillary condensation from a humid atmosphere plays the double role of electrolyte and a source of oxidizing species in the pattern printing process. It is shown that control over both the direction of pattern printing and metal transfer to one of the two monolayer surfaces can be accomplished by simple switching of the polarity of the applied voltage bias. Thus, the patterned metal film functions as a consumable "floating" stamp capable of two-way (forward-backward) electrochemical transfer of both information and matter between the contacting monolayer surfaces involved in the process. This rather unusual electrochemical behavior, resembling the electrochemical switching in nanoionic devices based on the transport of ions in solid ionic-electronic conductors, is derived from the nanoscale thickness of the water layer acting as an electrolyte and the bipolar (cathodic-anodic) nature of the water-coated metal grains in the metal film. The floating stamp concept introduced in this report paves the way to a series of unprecedented capabilities in surface patterning, which are particularly relevant to nanofabrication by chemical means and the engineering of a new class of molecular nanoionic systems. PMID:21661737

  11. Leaf-templated synthesis of 3D hierarchical porous cobalt oxide nanostructure as direct electrochemical biosensing interface with enhanced electrocatalysis.

    PubMed

    Han, Lei; Yang, Da-Peng; Liu, Aihua

    2015-01-15

    A novel three-dimensional (3D) hierarchical porous cobalt oxide (Co3O4) architecture was first synthesized through a simple, cost-effective and environmentally friendly leaf-templated strategy. The Co3O4 nanoparticles (30-100 nm) with irregular shapes were interconnected with each other to form a 3D multilayer porous network structure, which provided high specific surface area and numerous electrocatalytic active sites. Subsequently, Co3O4 was successfully utilized as direct electrochemical sensing interface for non-enzymatic detection of H2O2 and glucose. By using chronoamperometry, the current response of the sensor at +0.31 V was linear with H2O2 concentration within 0.4-200 ?M with a low limit of detection (LOD) of 0.24 ?M (S/N=3) and a high sensitivity of 389.7 ?A mM(-1) cm(-2). Two linear ranges of 1-300 ?M (with LOD of 0.1 ?M and sensitivity of 471.5 ?A mM(-1) cm(-2)) and 4-12.5 mM were found at +0.59 V for glucose. In addition, the as-prepared sensor showed excellent stability and anti-interference performance for possible interferents such as ascorbic acid, uric acid, dopamine, acetaminophen and especially 0.15 M chloride ions. Similarly, other various metal oxide nanostructures may be also prepared using this similar strategy for possible applications in catalysis, electrochemical sensors, and fuel cells. PMID:25078713

  12. Self-organized high aspect ratio porous hafnium oxide prepared by electrochemical anodization

    Microsoft Academic Search

    Hiroaki Tsuchiya; Patrik Schmuki

    2005-01-01

    We report on the fabrication of self-organized porous hafnium oxide layers by anodization of hafnium in H 2SO 4 electrolytes containing NaF. The results show that porous hafnium oxide layers can be formed under a range of experimental conditions. A key factor affecting the morphology and the structure of porous oxide is the anodization potential. Using optimized anodization conditions, highly

  13. A correlation between electrochemical behaviour, composition and semiconducting properties of naturally grown oxide films on copper

    Microsoft Academic Search

    B. Millet; C. Fiaud; C. Hinnen; E. M. M. Sutter

    1995-01-01

    Copper(I) oxide films formed under open-circuit potential in neutral aqueous solutions have been characterized, using coulometry, photocurrent spectroscopy and X-ray photo-electron spectroscopy (XPS). The reduction potential of the oxide layer was found to depend on the presence in the electrolyte of chloride ions, Cu(II) or Cu(I) ionic species or of a corrosion inhibitor. XPS analyses were performed on these oxide

  14. Structural and electrochemical evaluation of bismuth doped lithium titanium oxides for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Subburaj, T.; Prasanna, K.; Kim, Ki Jae; Ilango, P. Robert; Jo, Yong Nam; Lee, Chang Woo

    2015-04-01

    Micro-sized Li4Ti5-xBixO12 (0 ? x ? 0.15) materials are synthesized using a simple solid state method in air. The structural, morphological, and electrochemical characteristics of Bi-doped lithium titanates and pristine samples are methodically analyzed by X-ray diffraction (XRD), Raman spectroscopy, field emission-scanning electron microscopy (FE-SEM), and electrochemical impedance spectroscopy (EIS). The XRD and Raman spectroscopy results demonstrate that bismuth-doping do not alter the spinel structure and good crystalline materials are synthesized. The FE-SEM images show that all samples possess the same morphological characteristics, with a particle size distribution of 0.5-1 ?m. The electrochemical cycling testing reveals that the Li4Ti4.9Bi0.10O12 sample exhibits discharge capacities of 205.4 mAh g-1, 160.8 mAh g-1, and 135.4 mAh g-1 after 50 cycles at 1C, 5C, and 10C-rates, respectively. The differential capacity curves suggest that the Li4Ti4.9Bi0.10O12 sample has a weaker polarization effect than the other samples. The EIS measurements imply that the Li4Ti4.9Bi0.10O12 sample possesses a high electronic conductivity and lithium ion diffusivity, which demonstrate that this new Li4Ti4.9Bi0.10O12 material would be a good candidate as an anode for lithium ion batteries.

  15. Supporting electrodes for solid oxide fuel cells and other electrochemical devices

    DOEpatents

    Sprenkle, Vincent L. (Richland, WA); Canfield, Nathan L. (Kennewick, WA); Meinhardt, Kerry (Kennewick, WA); Stevenson, Jeffry W. (Richland, WA)

    2008-04-01

    An electrode supported electrolyte membrane includes an electrode layer 630 facing an electrolyte layer 620. The opposing side of the electrode layer 630 includes a backing layer 640 of a material with a thermal expansion coefficient approximately equal to the thermal expansion coefficient of the electrolyte layer 620. The backing layer 640 is in a two dimensional pattern that covers only a portion of the electrolyte layer 630. An electrochemical cell such as a SOFC is formed by providing a cathode layer 610 on an opposing side of the electrolyte layer 620.

  16. Electrochemical synthesis of nanocrystalline zinc oxide and phase transformations of zinc hydroxides

    Microsoft Academic Search

    Ingrid Grobelsek; Benjamin Rabung; Mario Quilitz; Michael Veith

    Nanoscaled ZnO was synthesized by an electrochemical process using zinc or Al-alloyed zinc electrodes in an aqueous system\\u000a with acetic acid as a conductive salt. Depending on the synthetical parameters, the precipitated precursor solids were found\\u000a to consist of various compounds such as zincite, presumably ?-Zn(OH)2, ?1-Zn(OH)2, ?-Zn(OH)2, Zn5(CO3)2(OH)6 and, in case an Al-alloyed electrode was used for the synthesis,

  17. New innovative materials for advanced electrochemical applications in battery and fuel cell systems

    Microsoft Academic Search

    S Voß; H Kollmann; W Kollmann

    2004-01-01

    The advanced material POLYMET is an innovative high tech polymer with a three-dimensional polymeric structure metallized with an enclosing coating of different kinds of metals or alloys. The result is a range of tailor-made, microporous structures on a designable scale. By varying the metals and alloys, it is possible to draw upon extremely diverse areas of applications such as battery

  18. Hierarchically designed three-dimensional macro/mesoporous carbon frameworks for advanced electrochemical capacitance storage.

    PubMed

    Yang, Yanbing; Li, Peixu; Wu, Shiting; Li, Xinyang; Shi, Enzheng; Shen, Qicang; Wu, Dehai; Xu, Wenjing; Cao, Anyuan; Yuan, Quan

    2015-04-13

    Mesoporous carbon (m-C) has potential applications as porous electrodes for electrochemical energy storage, but its applications have been severely limited by the inherent fragility and low electrical conductivity. A rational strategy is presented to construct m-C into hierarchical porous structures with high flexibility by using a carbon nanotube (CNT) sponge as a three-dimensional template, and grafting Pt nanoparticles at the m-C surface. This method involves several controllable steps including solution deposition of a mesoporous silica (m-SiO2 ) layer onto CNTs, chemical vapor deposition of acetylene, and etching of m-SiO2 , resulting in a CNT@m-C core-shell or a CNT@m-C@Pt core-shell hybrid structure after Pt adsorption. The underlying CNT network provides a robust yet flexible support and a high electrical conductivity, whereas the m-C provides large surface area, and the Pt nanoparticles improves interfacial electron and ion diffusion. Consequently, specific capacitances of 203 and 311?F?g(-1) have been achieved in these CNT@m-C and CNT@m-C@Pt sponges as supercapacitor electrodes, respectively, which can retain 96?% of original capacitance under large degree compression. PMID:25752493

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

    PubMed Central

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

    2015-01-01

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

  20. Advanced nitric oxide formation modeling in hypersonic flows

    NASA Astrophysics Data System (ADS)

    Bose, Deepak

    Nitric oxide (NO) is used as a diagnostic tool in a variety of high temperature flows. However, in order to interpret the experimental observations, a detailed kinetics simulation of NO is necessary. Thus far, the state-of-the-art simulations have been unable to adequately predict NO kinetics in these flows. It has been shown that the thermochemical models used for flow simulations fail to predict the spectral features of the ultraviolet emission from NO in hypersonic flows. This is due to the empirical nature of the current models, which are inadequate at high temperatures and strong nonequilibrium conditions. In this dissertation, an advanced modeling approach for NO formation in hypersonic flows is developed. Unlike most chemistry models currently in use, this approach is free of empirical assumptions and is valid over a wide range of conditions. The largest uncertainty in NO formation modeling is due to an inadequate treatment of the NO forming reactions: Nsb2+O-> NO+N and Osb2+N-> NO+O. A detailed quasiclassical trajectory study is done for these reactions based on ab initio data. This study provides the critically needed database of reaction attributes relevant for hypersonic flows. It is found that the thermal rate constants of these reactions are up to an order of magnitude higher than the currently used empirical rates. The obtained data show excellent agreement with the available experimental data. Furthermore, the thermal nonequilibrium is found to reduce the rate of the first reaction by up to a factor of 6. It is also shown that under nonequilibrium conditions, the NO molecules are formed with a higher vibrational energy than what the conventional simulations assume. These findings have significantly enhanced the NO formation modeling in hypersonic flows. On using this advanced model for continuum flow simulations, it is observed that the vibrational temperature of NO in the flow is higher than the predictions of the conventional simulations. This significantly improves the agreements with the experimental UV spectra at altitudes above 80 km. At lower altitudes, the uncertainties involved with other competing mechanisms cause a higher NO vibrational temperature than the one inferred from the spectra.

  1. Zinc oxide inverse opal electrodes modified by glucose oxidase for electrochemical and photoelectrochemical biosensor.

    PubMed

    Xia, Lei; Song, Jian; Xu, Ru; Liu, Dali; Dong, Biao; Xu, Lin; Song, Hongwei

    2014-09-15

    The ZnO inverse opal photonic crystals (IOPCs) were synthesized by the sol-gel method using the polymethylmethacrylate (PMMA) as a template. For glucose detection, glucose oxidase (GOD) was further immobilized on the inwall and surface of the IOPCs. The biosensing properties toward glucose of the Nafion/GOD/ZnO IOPCs modified FTO electrodes were carefully studied and the results indicated that the sensitivity of ZnO IOPCs modified electrode was 18 times than reference electrode due to the large surface area and uniform porous structure of ZnO IOPCs. Moreover, photoelectrochemical detection for glucose using the electrode was realized and the sensitivity approached to 52.4 µA mM(-1) cm(-2), which was about four times to electrochemical detection (14.1 µA mM(-1) cm(-2)). It indicated that photoelectrochemical detection can highly improve the sensor performance than conventional electrochemical method. It also exhibited an excellent anti-interference property and a good stability at the same time. This work provides a promising approach for realizing excellent photoelectrochemical biosensor of similar semiconductor photoelectric material. PMID:24752145

  2. IRON-PEROXYMONOSULFATE: A NOVEL SULFATE RADICAL BASED ADVANCED OXIDATION TECHNOLOGY FOR DEGRADATION OF PCBS

    EPA Science Inventory

    This study investigates the degradation of recalcitrant polychlorinated biphenyl (PCBs) using sulfate radical-based advanced oxidation technologies. Sulfate radicals are generated through coupling of peroxymonosulfate (PMS) with iron (Fe(II), Fe(III)). Sulfate radicals have very ...

  3. Modular Advanced Oxidation Process Enabled by Cathodic Hydrogen Peroxide Production.

    PubMed

    Barazesh, James M; Hennebel, Tom; Jasper, Justin T; Sedlak, David L

    2015-06-16

    Hydrogen peroxide (H2O2) is frequently used in combination with ultraviolet (UV) light to treat trace organic contaminants in advanced oxidation processes (AOPs). In small-scale applications, such as wellhead and point-of-entry water treatment systems, the need to maintain a stock solution of concentrated H2O2 increases the operational cost and complicates the operation of AOPs. To avoid the need for replenishing a stock solution of H2O2, a gas diffusion electrode was used to generate low concentrations of H2O2 directly in the water prior to its exposure to UV light. Following the AOP, the solution was passed through an anodic chamber to lower the solution pH and remove the residual H2O2. The effectiveness of the technology was evaluated using a suite of trace contaminants that spanned a range of reactivity with UV light and hydroxyl radical (HO(•)) in three different types of source waters (i.e., simulated groundwater, simulated surface water, and municipal wastewater effluent) as well as a sodium chloride solution. Irrespective of the source water, the system produced enough H2O2 to treat up to 120 L water d(-1). The extent of transformation of trace organic contaminants was affected by the current density and the concentrations of HO(•) scavengers in the source water. The electrical energy per order (EEO) ranged from 1 to 3 kWh m(-3), with the UV lamp accounting for most of the energy consumption. The gas diffusion electrode exhibited high efficiency for H2O2 production over extended periods and did not show a diminution in performance in any of the matrices. PMID:26039560

  4. Modular Advanced Oxidation Process Enabled by Cathodic Hydrogen Peroxide Production

    PubMed Central

    2015-01-01

    Hydrogen peroxide (H2O2) is frequently used in combination with ultraviolet (UV) light to treat trace organic contaminants in advanced oxidation processes (AOPs). In small-scale applications, such as wellhead and point-of-entry water treatment systems, the need to maintain a stock solution of concentrated H2O2 increases the operational cost and complicates the operation of AOPs. To avoid the need for replenishing a stock solution of H2O2, a gas diffusion electrode was used to generate low concentrations of H2O2 directly in the water prior to its exposure to UV light. Following the AOP, the solution was passed through an anodic chamber to lower the solution pH and remove the residual H2O2. The effectiveness of the technology was evaluated using a suite of trace contaminants that spanned a range of reactivity with UV light and hydroxyl radical (HO•) in three different types of source waters (i.e., simulated groundwater, simulated surface water, and municipal wastewater effluent) as well as a sodium chloride solution. Irrespective of the source water, the system produced enough H2O2 to treat up to 120 L water d–1. The extent of transformation of trace organic contaminants was affected by the current density and the concentrations of HO• scavengers in the source water. The electrical energy per order (EEO) ranged from 1 to 3 kWh m–3, with the UV lamp accounting for most of the energy consumption. The gas diffusion electrode exhibited high efficiency for H2O2 production over extended periods and did not show a diminution in performance in any of the matrices. PMID:26039560

  5. Advances in the identification of electrochemical transfer function models using Prony analysis

    SciTech Connect

    Trudnowski, D.J. [Pacific Northwest Lab., Richland, WA (United States); Donnelly, M.K. [Control Tech., Inc., Bozeman, MT (United States); Hauer, J.F. [USDOE Bonneville Power Administration, Portland, OR (United States)

    1993-02-01

    This paper further advances the usefulness and understanding of Prony analysis as a tool for identification of power system electromechanical oscillation models. These linear models are developed by analyzing power system ring-down data. The presented results allow more generality in the assumed model formulation. In addition, a comparison is made between Prony analysis and autoregressive moving-average (KARMA) modeling, which has also been proposed for analysis of system oscillations. Under the conditions investigated, the Prony algorithm performed more accurate identification.

  6. Electrochemical capacitive properties of Mn3O4 nanoparticles and reduced graphene oxide composite

    NASA Astrophysics Data System (ADS)

    Mitra, Arijit; Kalita, Hemen; Mohapatra, Jeotikanta; Aslam, Mohammed

    2013-06-01

    Manganese oxide (Mn3O4) nanoparticles are prepared in a facile one pot reaction using oleylamine as solvent reducing and surface functionalizing agent. A simple mixture of as synthesized Mn3O4 nanoparticles and reduced graphene oxide are tested as potential supercapacitor using cyclic voltammetry. The voltammograms are nearly perfect rectangular which indicates excellent capacitive nature of the nanoparticles-grapheme composite. A maximum specific capacitance of 170 Fg-1 is obtained in a potential range from-0.1 to 0.7 V which is higher than both reduced graphene oxide and Mn3O4 nanoparticles.

  7. Immobilization of Enzymes by Electrochemical and Chemical Oxidative Polymerization of L-DOPA to Fabricate Amperometric Biosensors and Biofuel Cells.

    PubMed

    Dai, Mengzhen; Sun, Lingen; Chao, Long; Tan, Yueming; Fu, Yingchun; Chen, Chao; Xie, Qingji

    2015-05-27

    Electrochemical/chemical oxidative synthesis and biosensing/biofuel cell applications of poly(L-DOPA) (PD) are studied versus polydopamine (PDA) as a recent hotspot biomaterial. The enzyme electrode developed by coelectrodeposition of PD and glucose oxidase (GOx), uricase, or tyrosinase shows biosensing performance superior to that of the corresponding PDA-based enzyme electrode. The chemical oxidative polymerization of L-DOPA (PDC) by NaAuCl4 in GOx-containing neutral aqueous solution is used to immobilize GOx and gold nanoparticles (AuNPs). The thus-prepared chitosan (CS)/GOx-PDC-AuNPs/Auplate/Au electrode working in the first-generation biosensing mode responds linearly to glucose concentration with a sensitivity of 152 ?A mM(-1) cm(-2), which is larger than those of the CS/GOx-PDAC-AuNPs/Auplate/Au electrode, the CS/GOx-poly(3-anilineboronic acid) (PABA)-AuNPs/Auplate/Au electrode, and the most reported GOx-based enzyme electrodes. This PDC-based enzyme electrode also works well in the second-generation biosensing mode and as an excellent bioanode in biofuel cell construction, probably because PD as an amino acid polymer has the higher biocompatibility and the more favorable affinity to the enzyme than PDA. The PD material of great convenience in synthesis, outstanding biocompatibility for preparing high-performance bionanocomposites, and strong capability of multifunctional coatings on many surfaces may find wide applications in diversified fields including biotechnology and surface-coating. PMID:25938891

  8. Effect of surface treatments on anodic oxide film growth and electrochemical properties of tantalum used for biomedical applications.

    PubMed

    Silva, R A; Silva, I P; Rondot, B

    2006-07-01

    Self-expandable nitinol (nickel-titanium) alloys and 316L stainless steel are the most commonly used materials in the production of coronary stents. However, tantalum (Ta) has already been used to make stents for endovascular surgery and may constitute an alternative to other materials because of its better electrochemical performance, namely its higher corrosion resistance, as well as its radio-opacity. The characterization of wet polished, chemically polished, wet polished anodized, and chemically polished anodized Ta electrodes has been performed in a 0.15 M NaCl solution (simulated body fluid) using Ucorr = f(t) measurements, anodic polarizations, capacity measurements, anodic oxidations, and atomic force microscopy (AFM) imaging. Anodic polarization curves have shown that the abnormal current density peak with a maximum value around 1.65 V (critical applied potential, Uc) disappeared for the anodized electrodes indicating a probable relationship between the surface states and the film growth. These results are confirmed by capacity measurements. The behavior of wet polished and chemically polished electrodes during anodic oxidations seemingly indicated that for these particular treatments the film growth is different. The AFM images and roughness measurements have shown that chemical polishing produced smoother electrodes, a fact probably related to the differences in film growth. PMID:16443631

  9. Endocrine Disrupting Compounds in Surface Water and Their Degradation by Advanced Oxidation Process with Ozone

    Microsoft Academic Search

    Ramiro Vallejo Rodríguez; Alberto López López

    \\u000a This chapter presents the state-of-the-art techniques for identification and analysis of endocrine disrupting compounds (EDCs) and their degradation by advanced oxidation processes (AOPs). The document arises from a research project oriented towards developing a pilot-level technology for advanced oxidation\\u000a using ozone for the degradation of EDCs present in surface water. Today EDCs are an environmental and public health problem.\\u000a Their

  10. Advanced Oxidation Processes for Treating Groundwater Contaminated With TCE and PCE: Pilot-Scale Evaluations

    Microsoft Academic Search

    E. Marco Aieta; Kevin M. Reagan; John S. Lang; Laurent McReynolds; Joon-Wun Kang; William H. Glaze

    1988-01-01

    This article presents the results of a pilot-scale evaluation of an advanced oxidation process that utilizes hydrogen peroxide and ozone. Treatment efficiency was determined as a function of the hydrogen peroxide-to-ozone dosage ratio, ozone dosage, and contact time. The ozone mass transfer characteristics of the process were also investigated. Comparison with other treatment technologies indicates that advanced oxidation can be

  11. Degradation of commercial reactive dyestuffs by heterogenous and homogenous advanced oxidation processes: a comparative study

    Microsoft Academic Search

    I. Arslan; I. Akmehmet Balcio?lu

    1999-01-01

    Advanced oxidation of the commercially available reactive dyestuffs Remazol Black B and Remazol Turquoise Blue G 133 in aqueous solution with TiO2-mediated photocatalytic and photoinduced and dark Fenton\\/Fenton-like reactions has been studied. Initial decolourization rates, effectiveness in removal of UV254 nm, COD as well as TOC were compared and evaluated. It was found that all advanced oxidation systems were capable

  12. Electrochemical lithiation and delithiation for control of magnetic properties of nanoscale transition metal oxides

    E-print Network

    Sivakumar, Vikram

    2008-01-01

    Transition metal oxides comprise a fascinating class of materials displaying a variety of magnetic and electronic properties, ranging from half-metallic ferromagnets like CrO2, ferrimagnetic semiconductors like Fey's, and ...

  13. Advanced Cu chemical displacement technique for SiO2-based electrochemical metallization ReRAM application.

    PubMed

    Chin, Fun-Tat; Lin, Yu-Hsien; You, Hsin-Chiang; Yang, Wen-Luh; Lin, Li-Min; Hsiao, Yu-Ping; Ko, Chum-Min; Chao, Tien-Sheng

    2014-01-01

    This study investigates an advanced copper (Cu) chemical displacement technique (CDT) with varying the chemical displacement time for fabricating Cu/SiO2-stacked resistive random-access memory (ReRAM). Compared with other Cu deposition methods, this CDT easily controls the interface of the Cu-insulator, the switching layer thickness, and the immunity of the Cu etching process, assisting the 1-transistor-1-ReRAM (1T-1R) structure and system-on-chip integration. The modulated shape of the Cu-SiO2 interface and the thickness of the SiO2 layer obtained by CDT-based Cu deposition on SiO2 were confirmed by scanning electron microscopy and atomic force microscopy. The CDT-fabricated Cu/SiO2-stacked ReRAM exhibited lower operation voltages and more stable data retention characteristics than the control Cu/SiO2-stacked sample. As the Cu CDT processing time increased, the forming and set voltages of the CDT-fabricated Cu/SiO2-stacked ReRAM decreased. Conversely, decreasing the processing time reduced the on-state current and reset voltage while increasing the endurance switching cycle time. Therefore, the switching characteristics were easily modulated by Cu CDT, yielding a high performance electrochemical metallization (ECM)-type ReRAM. PMID:25364318

  14. Electrochemical Properties of Low-Temperature Solid Oxide Fuel Cells Under Chromium Poisoning Conditions

    Microsoft Academic Search

    K. Min; C. W. Sun; W. Qu; X. G. Zhang; S. Yick; M. Robertson; C. Decès-Petit; R. Hui

    2009-01-01

    Rapid performance degradations of solid oxide fuel cells were observed when the chromium-forming metallic alloys were used as interconnects. The formation of strontium chromium oxide (SrCrO4) on the surface of Sr-doped perovskite cathode was believed to be one of the main causes for the cell degradation. This chromium-poisoning effect was not mitigated when the operating temperature was lowered to 600°C.

  15. Macroporous metal oxides: Synthesis, characterization and application in catalysis and electrochemical power sources

    Microsoft Academic Search

    Sergey Sokolov

    2003-01-01

    New approaches to the synthesis of magnesium, aluminum and nickel oxides with three-dimensionally ordered macroporous (3DOM) structure by colloidal crystal templating were explored. Such metal oxides were characterized by powder X-ray diffraction, scanning and transmission electron microscopy, thermogravimetric analysis, differential scanning calorimetry and nitrogen gas adsorption. Interconnected macropores, either organized in periodic arrays or positioned randomly, varied in diameter from

  16. Direct electrochemical synthesis of reduced graphene oxide (rGO)/copper composite films and their electrical/electroactive properties.

    PubMed

    Xie, Guoxin; Forslund, Mattias; Pan, Jinshan

    2014-05-28

    Electrical contact materials with excellent performances are crucial for the development and safe use of electrical contacts in different applications. In our work, reduced graphene oxide (rGO)/copper (Cu) composite films, as potential electrical contact materials, have been synthesized on copper foil with one-step electrochemical reduction deposition method. Cyclic voltammetry (CV) was used to define the deposition conditions, and confocal Raman microscopy (CRM), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to characterize the chemical compositions, molecular and micro- and nano-structures of the composite films. Atomic force microscopy/scanning Kelvin probe force microscopy (AFM/SKPFM), conductive AFM (C-AFM) as well as impedance analysis were employed to evaluate the electroactive/electrical properties of the prepared composite films, respectively. The CRM and XPS results suggest that the rGO/Cu composite films can be synthesized through one-step electrochemical codeposition using suitable precursor solutions. Within a short deposition period, the growth of discrete nanograins in the composite film predominates, whereas pine-tree-leaf nanostructures are formed in the composite film when the deposition period is long, due to the chelating role of GO or rGO to regulate the growth rate of metallic copper nanograins. The electrical resistivity of the composite films is lower than the polished Cu foil and the electrodeposited Cu film, probably due to the higher conductivity (enhanced transfer of charge carriers) of the rGO incorporated in the composite films. The Volta potential variation in the rGO/Cu composite film is quite different from that in the electrodeposited Cu film. The electroactivity of the rGO/Cu composite films is higher than the electrodeposited Cu film, but lower than polished Cu foil, and the underlying mechanisms have been discussed. PMID:24787038

  17. Cell and current collector felt arrangement for solid oxide electrochemical cell combinations

    DOEpatents

    Reichner, Philip (Plum Boro, PA)

    1988-01-01

    A solid electrolyte electrochemical cell combination 1 is made, comprising an annular, axially elongated, inner electrode 2 containing at least one interior gas feed conduit 3; annular solid electrolyte segments 4 around and covering portions of the inner electrode; annular outer electrode segments 6 around and covering portions of the electrolyte segments; electronically conducting, non-porous, interconnection material 5 disposed between electrolyte segments and in contact with the inner electrode, and electronically conducting, porous, metal fiber current collector felts 7 disposed on top of the non-porous interconnect material and outer electrode segments, where both the non-porous interconnect material and the porous metal felts are disposed circumferentially about the cell, transversely to the axial length of the cell and the inner electrode is continuous for the entire axial length of the cell combination.

  18. Electrochemical deposition of iron sulfide thin films and heterojunction diodes with zinc oxide

    SciTech Connect

    Kawai, Shoichi, E-mail: shoichi-kawai@denso.co.jp; Sobue, Susumu; Okuno, Eiichi [DENSO CORP. Research Laboratories, Komenoki, Nissin, Aichi 470-0111 (Japan); Yamazaki, Ryuta; Ichimura, Masaya [Department of Engineering Physics, Electronics and Mechanics, Nagoya Institute of Technology, Nagoya 466-8555 (Japan)

    2014-03-01

    Iron sulfide thin films were fabricated by the electrochemical deposition method from an aqueous solution containing FeSO{sub 4} and Na{sub 2}S{sub 2}O{sub 3}. The composition ratio obtained was Fe:S:O = 36:56:8. In the photoelectrochemical measurement, a weak negative photo-current was observed for the iron sulfide films, which indicates that its conduction type is p-type. No peaks were observed in X-ray diffraction pattern, and thus the deposited films were considered to be amorphous. For a heterojunction with ZnO, rectification properties were confirmed in the current-voltage characteristics. Moreover, the current was clearly enhanced under AM1.5 illumination.

  19. Advanced Oxidation Process Using Hydrogen Peroxide\\/ Microwave System for Solubilization of Phosphate

    Microsoft Academic Search

    PING HUANG LIAO; WAYNE T. WONG; KWANG VICTOR LO

    2005-01-01

    An advanced oxidation process (AOP) combining hydrogen peroxide and microwave heating was used for the solubilization of phosphate from secondary municipal sludge from an enhanced biological phosphorus removal process. The microwave irradiation is used as a generator agent of oxidizing radicals as well as a heating source in the process. This AOP process could facilitate the release of a large

  20. Receptor for Advanced Glycation End Products Activation Injures Primary Sensory Neurons via Oxidative Stress

    Microsoft Academic Search

    Andrea M. Vincent; Lorena Perrone; Kelli A. Sullivan; Carey Backus; Ann Marie Sastry; Christian Lastoskie; Eva L. Feldman

    2006-01-01

    The receptor for advanced glycation end products (RAGE) may promote diabetic vascular and renal disease through the activation of intracellular signaling pathways that promote oxidative stress. Oxidative stress is a mediator of hypergly- cemia-induced cell injury and a unifying theme for all mech- anisms of diabetic complications, but there are few studies on theexpressionandpotentialcontributionofRAGEindiabetic neuropathy. The current study demonstrates that

  1. Removal of rhodamine B by ozone-based advanced oxidation process

    Microsoft Academic Search

    Bai Cuiping; Xiong Xianfeng; Gong Wenqi; Feng Dexin; Xian Mo; Ge Zhongxue; Xu Nian

    2011-01-01

    The oxidation of rhodamine B in aqueous solution by conventional ozone process and the advanced ozone-based oxidation processes was investigated. The reaction conditions such as ozone dosage, initial concentration of the dye and pH in ozone process were optimized. The decolorization rate of rhodamine B increased with the ozone dosage but decreased with the initial concentration of rhodamine B. Three

  2. Phenol wastewater remediation: advanced oxidation processes coupled to a biological treatment

    Microsoft Academic Search

    A. Rubalcaba; M. E. Suárez-Ojeda; F. Stüber; A. Fortuny; C. Bengoa; I. Metcalfe; J. Carrera; A. Fabregat

    2007-01-01

    Nowadays, there are increasingly stringent regulations requiring more and more treatment of industrial effluents to generate product waters which could be easily reused or disposed of to the environment without any harmful effects. Therefore, different advanced oxidation processes were investigated as suitable precursors for the biological treatment of industrial effluents containing phenol. Wet air oxidation and Fenton process were tested

  3. Advanced oxidation processes (AOPs) for wastewater treatment: Formation of hydroxyl radical (·OH) and application

    Microsoft Academic Search

    JIANLONG WANG; LEJIN XU

    2011-01-01

    Advanced oxidation processes (AOPs), defined as those technologies that utilize the hydroxyl radical (·OH) for oxidation, have received increasing attention in the research and development of wastewater treatment technologies in the last decades. These processes have been applied successfully for the removal or degradation of toxic pollutants, or used as pretreatment to convert recalcitrant pollutants into biodegradable compounds which can

  4. Advanced Oxidation Processes for Wastewater Treatment: Formation of Hydroxyl Radical and Application

    Microsoft Academic Search

    JIAN LONG WANG; LE JIN XU

    2012-01-01

    Advanced oxidation processes (AOPs), defined as those technologies that utilize the hydroxyl radical (·OH) for oxidation, have received increasing attention in the research and development of wastewater treatment technologies in the last decades. These processes have been applied successfully for the removal or degradation of toxic pollutants or used as pretreatment to convert recalcitrant pollutants into biodegradable compounds that can

  5. An electrochemical biosensor for analysis of Fenton-mediated oxidative damage to BSA using poly-o-phenylenediamine as electroactive probe.

    PubMed

    Bian, Chunli; Xiong, Huayu; Zhang, Xiuhua; Wen, Wei; Wang, Shengfu

    2011-10-15

    A sensitive electrochemical procedure based on bovine serum albumin (BSA)/poly-o-phenylenediamine (PoPD)/carbon-coated nickel (C-Ni) nanobiocomposite film modified glassy carbon electrode (BSA/PoPD/C-Ni/GCE) has been developed to explore the electrochemical detection of BSA damage induced by hydroxyl radical. It is the first time that the electrochemical method has been applied for the analysis of Fenton-mediated oxidative damage to proteins. The hydroxyl radical was generated by Fenton reaction (Fe(2+)/H(2)O(2)), which was also validated by ultraviolet-visible (UV-vis) spectroscopy. The decrease in intensity of the PoPD oxidation signals was used as an indicator for the detection of BSA damage. Damage to BSA was also validated by horizontal Attenuation Total Reflection Fourier Transform Infra-red (ATR-FTIR) spectroscopy and the change of protein carbonyl group content achieved by UV-vis spectroscopy. Effects of H(2)O(2) concentration, the ratio of Fe(2+) and H(2)O(2) and incubation time on BSA damage were examined. Protections of BSA from damage by antioxidants were also investigated. These conclusions demonstrated that the proposed electrochemical method is expected to the further application for protein damage studies. PMID:21816601

  6. Modelling and Ni/Yttria-Stabilized-Zirconia pattern anode experimental validation of a new charge transfer reactions mechanism for hydrogen electrochemical oxidation on solid oxide fuel cell anodes

    NASA Astrophysics Data System (ADS)

    Yao, Weifang; Croiset, Eric

    2014-02-01

    Good understanding of the H2 electrochemical reaction mechanism helps optimize SOFC anode design and improve its performance. Controversies still exist regarding H2 oxidation mechanism despite extensive studies performed. In this work, a new charge transfer reactions mechanism proposed by Shishkin and Ziegler (2010) based on Density Functional Theory (DFT) study was investigated through kinetic modelling and pattern anode experimental validation. The new charge transfer reactions mechanism considers hydrogen oxidation at the interface of Ni and YSZ. It involves a hydrogen atom reacting with the oxygen ions bound to both Ni and YSZ to produce hydroxyl (Charge transfer reaction 1), the latter reacting with the other hydrogen atom to form water (Charge transfer reaction 2). The predictive capability of this reaction mechanism to represent our experimental results was evaluated. The simulated Tafel plots were compared with our experimental data for a wide range of H2 and H2O partial pressures and at different temperatures. Good agreements between simulation and experimental results were obtained. Charge transfer reaction 1 was found to dominate the overall charge transfer reaction under cathodic polarization. Under anodic polarization, a change in the dominating charge transfer reaction from charge transfer reaction 1 to charge transfer reaction 2 was found when increasing the H2O partial pressure.

  7. Au-ionic liquid functionalized reduced graphene oxide immunosensing platform for simultaneous electrochemical detection of multiple analytes.

    PubMed

    Liu, Na; Ma, Zhanfang

    2014-01-15

    In this work, an Au-ionic liquid functionalized reduced graphene oxide nanocomposite (IL-rGO-Au) was fabricated via the self-assembly of ionic liquid functionalized reduced graphene oxide (IL-rGO) and gold nanoparticles (AuNPs) by electrostatic interaction. The IL-rGO can be synthesized and stabilized by introducing the cations of the amine-terminated ionic liquids (IL-NH2) into the graphene oxide (GO). With the assistance of IL-NH2, AuNPs were uniformly and densely absorbed on the surfaces of the IL-rGO. The proposed IL-rGO-Au nanocomposite can be used as an immunosensing platform because it can not only facilitate the electrons transfer of the electrode surface but also provide a large accessible surface area for the immobilization of abundant antibody. To assess the performance of the IL-rGO-Au nanocomposite, a sandwich-type electrochemical immunosensor was designed for simultaneous multianalyte detection (carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP) as model analytes). The chitosan (CS) coated prussian blue nanoparticles (PBNPs) or cadmium hexacyanoferrate nanoparticles (CdNPs) and loaded with AuNPs were used as distinguishable signal tags. The resulting immunosensor exhibited high selectivity and sensitivity in simultaneous determination of CEA and AFP in a single run. The linear ranges were from 0.01 to 100 ng mL(-1) for both CEA and AFP. The detection limits reached 0.01 ng mL(-1) for CEA and 0.006 ng mL(-1) for AFP, respectively. No obvious nonspecific adsorption and cross-talk was observed during a series of analyses to detect target analytes. In addition, for the detection of clinical serum samples, it is well consistent with the data determined by the ELISA, indicating that the immunosensor provides a possible application for the simultaneous multianalyte determination of CEA and AFP in clinical diagnostics. PMID:23962704

  8. Direct access to metal or metal oxide nanocrystals integrated with one-dimensional nanoporous carbons for electrochemical energy storage.

    PubMed

    Liang, Yanyu; Schwab, Matthias Georg; Zhi, Linjie; Mugnaioli, Enrico; Kolb, Ute; Feng, Xinliang; Müllen, Klaus

    2010-10-27

    Metal and metal oxide nanocrystals have sparked great interest due to their excellent catalytic, magnetic, and electronic properties. Particularly, the integration of metallic nanocrystals and one-dimensional (1D) electronically conducting carbons to form metal-carbon hybrids can lead to enhanced physical and chemical properties or even the creation of new properties with respect to single component materials. However, direct access to thermally stable and structurally ordered 1D metal-carbon hybrids remains a primary challenge. We report an in situ fabrication of Co(3)O(4) or Pt nanocrystals incorporated into 1D nanoporous carbons (NPCs) via an organometallic precursor-controlled thermolysis approach. The AB(2)-type (one diene and two dienophile) 3,4-bis(4-dodecynylphenyl)-substituted cyclopentadienone and its relevant cobalt or platinum complex are first impregnated into the nanochannels of AAO (anodic alumina oxide) membranes. The intermolecular Diels-Alder reaction of these precursor molecules affords the formation of cobalt or platinum functionalized polyphenylene skeletons. Subsequent thermolysis transforms the polyphenylene backbones into 1D nanoporous carbonaceous frameworks, while the metallic moieties are reduced into Co or Pt nanocrystals, respectively. After removal of the AAO template, 1D NPCs/Co(3)O(4) or NPCs/Pt are obtained, for which structural characterizations reveal that high-quality Co(3)O(4) or Pt nanocrystals are distributed homogeneously within carbon frameworks. These unique 1D metal-carbon hybrids exhibit a promising potential in electrochemical energy storage. NPCs/Co(3)O(4) is evaluated as an electrode material in a supercapacitor, for which Co(3)O(4) nanocrystals contribute an exceptionally high gravimetric capacitance value of 1066 F g(-1). NPCs/Pt is applied as an electrocatalyst showing excellent catalytic efficiency toward methanol oxidation in comparison to commercial E-TEK (Pt/C) catalyst. PMID:20886853

  9. The ozonizer discharge as a gas-phase advanced oxidation process

    Microsoft Academic Search

    Rosocha

    1997-01-01

    In the past several years, there has been increased interest in gas-phase pollution control arising from a larger body of environmental regulations and a greater respect for the environment. One promising class of pollution-control technologies is that called advanced oxidation processes (AOPs). Ozonizers have been used for over a century in water treatment and for about two decades in advanced

  10. Integrated Fenton Oxidation Process for Advanced Treatment of Biologically Treated Coking Plant Effluent

    Microsoft Academic Search

    Wenxing Jiang; Guangyu Zhang; Weichi Ying

    2009-01-01

    Experiments of Fenton oxidation, carbon adsorption, and Fenton oxidation plus carbon adsorption were conducted to develop a cost effective advanced treatment process for treating a biotreated coking plant effluent. Fenton oxidation (Fe2+ = 56 mg\\/L and H2O2 = 27.2 mg\\/L) was effective for removing >50% organic pollutants, measured as UV254 (aromatic organics), ViS380 (color ingredients) and COD and most total

  11. Advanced oxidation processes for the treatment of olive-oil mills wastewater

    Microsoft Academic Search

    P. Cañizares; J. Lobato; R. Paz; M. A. Rodrigo; C. Sáez

    2007-01-01

    In this work, the treatment of an actual industrial waste with three advanced oxidation processes (AOP) has been studied: conductive-diamond electrooxidation (CDEO), ozonation and Fenton oxidation. The wastewater comes from olive-oil mills (OMW) and contains a COD of nearly 3000mgdm?3. CDEO allowed achieving the complete mineralization of the waste with high current efficiencies. Likewise, both ozonation and Fenton oxidation were

  12. Degradation of Phthalic Acids and Benzoic Acid from Terephthalic Acid Wastewater by Advanced Oxidation Processes

    Microsoft Academic Search

    Ramesh Thiruvenkatachari; Tae Ouk Kwon; Il Shik Moon

    2006-01-01

    Terephthalic acid (TPA) wastewater is traditionally being treated by biological method. This study investigates the degradation of three major toxic target organic species, namely terephthalic acid (TPA), isophthalic acid (IPA), benzoic acid (BA), present in the TPA wastewater, by several advanced oxidation processes. The performance of three main oxidation processes such as photofenton oxidation (UV-H2O2-Fe), photocatalytic ozonation (UV-O3-Fe) and photofenton

  13. An Electrochemical Sensor Based on Nanostructured Hollandite-type Manganese Oxide for Detection of Potassium Ions

    PubMed Central

    Lima, Alex S.; Bocchi, Nerilso; Gomes, Homero M.; Teixeira, Marcos F. S.

    2009-01-01

    The participation of cations in redox reactions of manganese oxides provides an opportunity for development of chemical sensors for non-electroactive ions. A sensor based on a nanostructured hollandite-type manganese oxide was investigated for voltammetric detection of potassium ions. The detection is based on the measurement of anodic current generated by oxidation of Mn(III) to Mn(IV) at the surface of the electrode and the subsequent extraction of the potassium ions into the hollandite structure. In this work, an amperometric procedure at an operating potential of 0.80 V (versus SCE) is exploited for amperometric monitoring. The current signals are linearly proportional to potassium ion concentration in the range 4.97 × 10?5 to 9.05 × 10?4 mol L?1, with a correlation coefficient of 0.9997. PMID:22399969

  14. Permeable membrane mass spectrometry of products of electrochemical oxidation of carboxylate ions

    SciTech Connect

    Brockman, T.J.; Anderson, L.B.

    1984-02-01

    The volatile products of Kolbe oxidation of carboxylate ions in water and Me/sub 2/SO solvents have been detected by permeable membrane mass spectrometry (PERMS). Deconvolution of the mass spectral data by factor analysis allows estimation of carbon dioxide, oxygen, and ethane during the course of electrolysis. In water solutions, electrolysis of water occurs in competition with Kolbe oxidation, and it is possible to follow the individual current efficiencies for these two processes as a function of potential. In Me/sub 2/SO solutions, the oxidation of propionate and acetate led to the same products, CO/sub 2/ and ethane, but in different stoichiometric proportions. Efficiencies for ethane production are twice as large for propionate as for acetate. 23 references, 6 figures, 8 tables.

  15. Electrochemical fabrication and optical properties of porous tin oxide films with structural colors

    SciTech Connect

    Cheng, Hua; Shu, Shiwei; Lee, Chris; Zeng, Shanshan [Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, 83 Tat Chee Av. Hong Kong (Hong Kong); Centre for Functional Photonics, City University of Hong Kong, 83 Tat Chee Av. Hong Kong (Hong Kong); Department of Physics and Materials Science, City University of Hong Kong, 83 Tat Chee Avenue (Hong Kong); Lu, Zhouguang [Department of Materials Science and Engineering, South University of Science and Technology of China, Shenzhen, Guangdong 518055 (China); Lu, Jian, E-mail: jianlu@cityu.edu.hk, E-mail: yangli@cityu.edu.hk [Department of Mechanical and Biomedical Engineering, City University of Hong Kong, Kowloon (Hong Kong); Centre for Advanced Structural Materials, City University of Hong Kong Shenzhen Research Institute, 8 Yuexing 1st Road, Shenzhen Hi-Tech Industrial Park, Nanshan District, Shenzhen (China); Li, Yang Yang, E-mail: jianlu@cityu.edu.hk, E-mail: yangli@cityu.edu.hk [Center of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, 83 Tat Chee Av. Hong Kong (Hong Kong); Centre for Functional Photonics, City University of Hong Kong, 83 Tat Chee Av. Hong Kong (Hong Kong); Department of Physics and Materials Science, City University of Hong Kong, 83 Tat Chee Avenue (Hong Kong); City University of Hong Kong Shenzhen Research Institute, 8 Yuexing 1st Road, Shenzhen Hi-Tech Industrial Park, Nanshan District, Shenzhen (China)

    2014-10-21

    Photonic crystals with porous features not only provide the capability to control light but also enable structural colors that are environmentally sensitive. Here, we report a novel kind of tin oxide-based photonic crystal featuring periodically arranged air pores fabricated by the periodic anodization of tin foil. The existence of a photonic band gap in the fabricated structure is verified by its vivid color, and its reflective spectra which are responsive to environmental stimuli. Furthermore, the sample colors (i.e., the photonic band gap positions) can be easily adjusted by manipulating the anodization parameters. The theoretical modeling results of these tin oxide photonic crystals agree well with the reported experimental ones.

  16. Effects of complex agents on the anodic deposition and electrochemical characteristics of cobalt oxides

    Microsoft Academic Search

    Chi-Chang Hu; Tung-Yu Hsu

    2008-01-01

    The anodic deposition rate of cobalt oxide from CoCl2·6H2O is strongly affected by the type of complex agents (acetate ion (AcO?), citrate ion, EDTA) added into the deposition solutions. The oxidation potential of CoCl2·6H2O, examined by linear sweep voltammetry (LSV), is negatively shifted from ca. 1.1V to about 0.8, 0.5, and 0.2V by adding AcO?, citrate ion, and EDTA, respectively.

  17. X-ray absorption spectroscopy studies of electrochemically deposited thin oxide films.

    SciTech Connect

    Balasubramanian, M.

    1998-06-02

    We have utilized ''in situ'' X-ray Absorption Fine Structure Spectroscopy to investigate the structure and composition of thin oxide films of nickel and iron that have been prepared by electrodeposition on a graphite substrate from aqueous solutions. The films are generally disordered. Structural information has been obtained from the analysis of the data. We also present initial findings on the local structure of heavy metal ions, e.g. Sr and Ce, incorporated into the electrodeposited nickel oxide films. Our results are of importance in a number of technological applications, among them, batteries, fuel cells, electrochromic and ferroelectric materials, corrosion protection, as well as environmental speciation and remediation.

  18. Handbook of Electrochemical Nanotechnology

    SciTech Connect

    Lin, Yuehe; Nalwa, H. S.

    2009-02-12

    This 2-volume handbook provides an overview of recent advances in the field of electrochemical nanotechnology. It will be of great interst to graduate students, scientists, and engineering professionals whose research is at the interface of electrochemistry and nanotechnology.

  19. Electrochemical impedance spectroscopy of porous ZrO 2–8 wt.% Y 2O 3 and thermally grown oxide on nickel aluminide

    Microsoft Academic Search

    B. Jayaraj; V. H. Desai; C. K. Lee; Y. H. Sohn

    2004-01-01

    Electrochemical impedance spectroscopy (EIS) is being developed as a non-destructive evaluation (NDE) technique for life-remain assessment and quality control of thermal barrier coatings (TBCs). In this investigation, EIS was employed to non-destructively examine impedance and capacitance behavior of monolithic ZrO2–8wt.%Y2O3 (8YSZ) with open pores as a function of thickness and density. Also, the growth and spallation of thermally grown oxide

  20. Electrochemical catalysis of styrene epoxidation with films of manganese dioxide nanoparticles, and, Synthesis of mixed metal oxides using ultrasonic nozzle spray and microwaves

    Microsoft Academic Search

    Laura Espinal

    2005-01-01

    Films of polyions and octahedral layered manganese oxide (OL-1) nanoparticles on carbon electrodes made by layer-by-layer alternate electrostatic adsorption were active for electrochemical catalysis of styrene epoxidation in solution in the presence of hydrogen peroxide and oxygen. The highest catalytic turnover was obtained by using applied voltage -0.6 V vs. SCE, O2, and 100 mM H2O2. 18O isotope labeling experiments

  1. Electrochemical insertion of lithium in thecation-deficient mixed spinel oxide Mn 2.15Co 0.37O 4

    Microsoft Academic Search

    Luis Sánchez; Jacqueline Farcy; Jean-Pierre Pereira-Ramos

    1997-01-01

    Abstract. Electrochemical properties of a cation-deficient mixed spinel oxide Mn2.15Co0.37O4 are investigated. Potentiometric, voltammetric and ac impedance experiments are performed to provide thermodynamic and kinetic data on the lithium insertion reaction vsx in the LixMn2.15Co0.37O4 system operating below 3 V with one single step. While no evidence for significant structural change is found and in spite of numerous cation vacancies,

  2. Constraints on the oxidation state of the mantle: An electrochemical and sup 57 Fe Moessbauer study of mantle-derived ilmenites

    Microsoft Academic Search

    D. Virgo; R. W. Luth; M. A. Moats; G. C. Ulmer

    1988-01-01

    Ilmenite samples from four kimberlite localities were studied using electrochemical, Moessbauer spectroscopic, and microprobe analytical techniques in order to infer the oxidation state of their source regions in the mantle. The values of Fe{sup 3+}\\/ΣFe calculated from analyses, using three different electron microanalytical instruments assuming ilmenite stoichiometry, are consistently higher than those derived from the Moessbauer data, by as much

  3. Electrochemical Oxidation of Iodide in the Presence of Benzenesulfinic Acids and Its Application to the Quasi-Catalytic Determination of Benzenesulfinic Acids

    Microsoft Academic Search

    Davood Nematollahi; Zinat Forooghi; Esmail Tammari

    2005-01-01

    The mechanism of the electrochemical oxidation of iodide in the presence of 4-toluenesulfinic acid was studied in an aqueous solution using cyclic voltammetry and controlled-potential coulometry. The results indicate that the anodically generated iodine reacts with 4-toluenesulfinic acid through a quasi-catalytic process. In addition, the results indicate the suitability of iodide as a mediator for the determination of 4-toluene-sulfinic acid

  4. Recent advances in iron oxide nanocrystal technology for medical imaging

    Microsoft Academic Search

    Claire Corot; Philippe Robert; Jean-Marc Idée; Marc Port

    2006-01-01

    Superparamagnetic iron oxide particles (SPIO and USPIO) have a variety of applications in molecular and cellular imaging. Most of the recent research has concerned cellular imaging with imaging of in vivo macrophage activity. According to the iron oxide nanoparticle composition and size which influence their biodistribution, several clinical applications are possible: detection liver metastases, metastatic lymph nodes, inflammatory and\\/or degenerative

  5. Electrochemical model of the integrated planar solid oxide fuel cell (IP-SOFC)

    Microsoft Academic Search

    Paola Costamagna; Azra Selimovic; Marco Del Borghi; Gerry Agnew

    2004-01-01

    The Integrated Planar Solid Oxide Fuel Cell (IP-SOFC) is an innovative fuel cell concept which is substantially a cross between tubular and planar geometries, seeking to borrow thermal compliance properties from the former and low cost component fabrication and short current paths from the latter. In this study, a simulation model for the IP-SOFC is presented, with particular highlight on

  6. Ternary Self-Assembly of Ordered Metal Oxide-Graphene Nanocomposites for Electrochemical Energy Storage

    SciTech Connect

    Wang, Donghai; Kou, Rong; Choi, Daiwon; Yang, Zhenguo; Nie, Zimin; Li, Juan; Saraf, Laxmikant V.; Hu, Dehong; Zhang, Jiguang; Graff, Gordon L.; Liu, Jun; Pope, Michael A.; Aksay, Ilhan A.

    2010-02-25

    Surfactant or polymer directed self-assembly has been widely investigated to prepare nanostructured metal oxides, semiconductors and polymers, but this approach is mostly limited to two-phase materials, organic/inorganic hybrids, and nanoparticle or polymer-based nanocomposites. Self-assembled nanostructures from more complex, multiscale and multiphase building blocks have been explored with limited success. Here, we demonstrate a ternary self-assembly approach using graphene as fundamental building blocks to construct metal oxide-graphene nanocomposites. A new class of layered nanocomposites is formed containing stable, ordered alternating layers of nanocrystalline metal oxides with graphene/graphene stacks. Alternatively, the graphene material can be incorporated into liquid-crystal-templated nanoporous structures to form high surface area, conductive networks. The self-assembly method can be also used to fabricate free standing, flexible metal oxide-graphene nanocomposite films and electrodes. We investigate the Li-ion insertion properties of the self-assembled electrodes for energy storage and show that the SnO2-graphene nanocomposite films can achieve near theoretical specific energy density without a significant charge/discharge degradation.

  7. Synthesis of graphene-supported monodisperse AuPd bimetallic nanoparticles for electrochemical oxidation of methanol

    NASA Astrophysics Data System (ADS)

    Xiao, Hong-Jun; Shen, Cheng-Min; Shi, Xue-Zhao; Yang, Su-Dong; Tian, Yuan; Lin, Shao-Xiong; Gao, Hong-Jun

    2015-07-01

    Monodisperse AuPd bimetallic nanoparticles (NPs) with different compositions are synthesized by using oleylamine (OAm) as reducing reagent, stabilizer, and solvent. To obtain AuPd solid solution NPs, Pd–OAm and Au–OAm precursors are firstly prepared by mixing OAm with Palladium (II) acetylacetonate (Pd(acac)2) and HAuCl4, respectively. Then Pd–OAm and Au–OAm precursor solutions are injected into a hot oleylamine solution to form AuPd NPs. The size of these NPs ranges from 6.0 to 8.0 nm and the composition is controlled by varying the precursor ratio. The AuPd NPs are loaded onto reduced graphene oxide (RGO) sheets to make catalysts. Alloy NPs show high electrocatalytic activity and stability toward methanol oxidation in the alkaline media. Their catalytic activity for methanol oxidation is found to be dependent on the NP composition. As the Pd component increases, the peak current densities during the forward scan gradually increase and reach the maximum at AuPd2. The enhancement of alloy NPs for methanol oxidation can be attributed to a synergistic effect of Au and Pd on the surface of alloy NPs. Project supported by the National Natural Science Foundation of China (Grant No. 61335006) and the National Basic Research Program of China (Grant No. 2013CBA01603).

  8. Electrochemical detection of DNA hybridization based on bismuth oxide nanoparticles\\/chitosan-modified electrodes with methylene blue as an electrochemical indicator

    Microsoft Academic Search

    N. A. Yusof; S. Taufik; Tan Wee Tee; I. Ramli

    2010-01-01

    The detection of DNA hybridization is of central importance to the diagnostic and treatment of genetic diseases, for the detection of infectious agents, and for reliable forensic analysis. The technique for the detection of DNA hybridization has attracted many attentions. Many methods for detecting hybridization have been developed, including electrochemical, optical, microgravimetric methods and surface plasma resonance. As compared with

  9. Effect of electrochemical oxidation of activated carbon fiber on competitive and noncompetitive sorption of trace toxic metal ions from aqueous solution.

    PubMed

    Harry, I D; Saha, B; Cumming, I W

    2006-12-01

    A viscose-rayon-based activated carbon cloth (ACC) was electrochemically oxidized to enhance its cation sorption capacity for comparison with as-received ACC. The ACCs were characterized by sodium capacity measurement, pH titration, zeta potential measurement, elemental analysis, Brunauer-Emmet-Teller surface area, and pore size distribution. Batch sorption experiments showed that electrochemically oxidized ACC (EO) is more effective for the removal of lead and copper ions compared to unoxidized ACC (UO) for both competitive and noncompetitive sorption. For electrochemically oxidized fibers the copper and lead sorption capacities of ACC increased 17 and 4 times, respectively, for noncompetitive sorption and 8.8 and 8.6 times, respectively, for competitive sorption. However, reduction in the sorption capacities for both metals was observed for the competitive sorption. The sorption of lead and copper onto EO was by ion exchange, while that onto UO was likely to be due to surface complex formation. The affinity order of the two metal ions sorbed by UO and EO is Pb(2+)>Cu(2+). The effect of pH on sorption isotherms indicated that metal uptake increased with an increase in solution pH. PMID:17011569

  10. Ag x VOPO 4: A demonstration of the dependence of battery-related electrochemical properties of silver vanadium phosphorous oxides on Ag\\/V ratios

    Microsoft Academic Search

    Young Jin Kim; Chia-Ying Lee; Amy C. Marschilok; Kenneth J. Takeuchi; Esther S. Takeuchi

    2011-01-01

    As a part of our on-going study on silver vanadium phosphorous oxides (AgxVyOzPO4), we report here the first study of the electrochemical reduction of a low Ag\\/V ratio silver vanadium phosphorous oxide, Ag0.48VOPO4·1.9H2O. Reminiscent of Ag2VO2PO4 reduction, in situ formation of silver metal nanoparticles along with an associated increase in conductivity were observed after reduction of Ag0.48VOPO4·1.9H2O with 0.37 electron

  11. Core-shell tin oxide, indium oxide, and indium tin oxide nanoparticles on silicon with tunable dispersion: electrochemical and structural characteristics as a hybrid Li-ion battery anode.

    PubMed

    Osiak, Michal J; Armstrong, Eileen; Kennedy, Tadhg; Torres, Clivia M Sotomayor; Ryan, Kevin M; O'Dwyer, Colm

    2013-08-28

    Tin oxide (SnO2) is considered a very promising material as a high capacity Li-ion battery anode. Its adoption depends on a solid understanding of factors that affect electrochemical behavior and performance such as size and composition. We demonstrate here, that defined dispersions and structures can improve our understanding of Li-ion battery anode material architecture on alloying and co-intercalation processes of Lithium with Sn from SnO2 on Si. Two different types of well-defined hierarchical Sn@SnO2 core-shell nanoparticle (NP) dispersions were prepared by molecular beam epitaxy (MBE) on silicon, composed of either amorphous or polycrystalline SnO2 shells. In2O3 and Sn doped In2O3 (ITO) NP dispersions are also demonstrated from MBE NP growth. Lithium alloying with the reduced form of the NPs and co-insertion into the silicon substrate showed reversible charge storage. Through correlation of electrochemical and structural characteristics of the anodes, we detail the link between the composition, areal and volumetric densities, and the effect of electrochemical alloying of Lithium with Sn@SnO2 and related NPs on their structure and, importantly, their dispersion on the electrode. The dispersion also dictates the degree of co-insertion into the Si current collector, which can act as a buffer. The compositional and structural engineering of SnO2 and related materials using highly defined MBE growth as model system allows a detailed examination of the influence of material dispersion or nanoarchitecture on the electrochemical performance of active electrodes and materials. PMID:23952971

  12. Laser-induced electrochemical de- and repassivation investigations on plasma-oxidized aluminium alloys

    NASA Astrophysics Data System (ADS)

    Nagy, Tristan O.; Pacher, Ulrich; Giesriegl, Ariane; Soyka, Lukas; Trettenhahn, Günter; Kautek, Wolfgang

    2014-05-01

    In situ laser depassivation of plasma electrolytically oxididized (PEO) coatings on aluminium was investigated with nanosecond pulses. Ultraviolet radiation of 266 nm was chosen in order to achieve a high absorption in the dielectric coating. The additive accumulation of laser-induced material defects (incubation) affected the depassivation processes. Incubation occurred only at the edges of the ablation craters irradiated by the outer region of the Gaussian beam profile, where the local fluence is below the ablation threshold. The ablation rate in the spot center did not exhibit an incubation effect. Repassivation was interpreted by a linear combination of a high-field and a point defect growth model. At low overpotentials, field gradients affect the process driving the oxide growth at the buried interface. At high fields, corrosion reactions dominate at the oxide/solution interface.

  13. Electrochemical and structural characterization of titanium-substituted manganese oxides based on Na0.44MnO2

    SciTech Connect

    Doeff, Marca M.; Richardson, Thomas J.; Hwang, Kwang-Taek

    2004-03-01

    A series of titanium-substituted manganese oxides, Li{sub x}Ti{sub y}Mn{sub 1-y}O{sub 2} (y = 0.11, 0.22, 0.33, 0.44, and 0.55) with the Na{sub 0.44}MnO{sub 2} structure were prepared from Na{sub x}Ti{sub y}Mn{sub 1-y}O{sub 2} (x {approx} 0.44) precursors. The electrochemical characteristics of these compounds, which retain the unique double-tunnel structure during ion exchange, were examined in lithium/polymer electrolyte cells operating at 85 C. All of the substituted cathode materials intercalated lithium reversibly, with Li{sub x}Ti{sub 0.22}Mn{sub 0.78}O{sub 2} exhibiting the highest capacity in polymer cells, about 10-20% greater than that of unsubstituted Li{sub x}MnO{sub 2} made from Na{sub 0.44}MnO{sub 2}. In common with Li{sub x}MnO{sub 2}, the Ti-substituted materials exhibited good capacity retention over one hundred or more cycles, with some compositions exhibiting a fade rate of less than 0.03% per cycle.

  14. Electrochemical deposition of ZnO nanorods on transparent reduced graphene oxide electrodes for hybrid solar cells.

    PubMed

    Yin, Zongyou; Wu, Shixin; Zhou, Xiaozhu; Huang, Xiao; Zhang, Qichun; Boey, Freddy; Zhang, Hua

    2010-01-01

    Monocrystalline ZnO nanorods (NRs) with high donor concentration are electrochemically deposited on highly conductive reduced graphene oxide (rGO) films on quartz. The film thickness, optical transmittance, sheet resistance, and roughness of rGO films are systematically studied. The obtained ZnO NRs on rGO films are characterized by X-ray diffraction, transmission electron microscopy, photoluminescence, and Raman spectra. As a proof-of-concept application, the obtained ZnO NRs on rGO are used to fabricate inorganic-organic hybrid solar cells with layered structure of quartz/rGO/ZnO NR/poly(3-hexylthiophene)/poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (P3HT/PEDOT:PSS)/Au. The observed power conversion efficiency (PCE, eta), approximately 0.31%, is higher than that reported in previous solar cells by using graphene films as electrodes. These results clearly demonstrate that rGO films with a higher conductivity have a smaller work function and show a better performance in the fabricated solar cells. PMID:20039255

  15. Tunable electrochemical pH modulation in a microchannel monitored via the proton-coupled electro-oxidation of hydroquinone.

    PubMed

    Contento, Nicholas M; Bohn, Paul W

    2014-07-01

    Electrochemistry is a promising tool for microfluidic systems because it is relatively inexpensive, structures are simple to fabricate, and it is straight-forward to interface electronically. While most widely used in microfluidics for chemical detection or as the transduction mechanism for molecular probes, electrochemical methods can also be used to efficiently alter the chemical composition of small (typically <100 nl) microfluidic volumes in a manner that improves or enables subsequent measurements and sample processing steps. Here, solvent (H2O) electrolysis is performed quantitatively at a microchannel Pt band electrode to increase microchannel pH. The change in microchannel pH is simultaneously tracked at a downstream electrode by monitoring changes in the i-V characteristics of the proton-coupled electro-oxidation of hydroquinone, thus providing real-time measurement of the protonated forms of hydroquinone from which the pH can be determined in a straightforward manner. Relative peak heights for protonated and deprotonated hydroquinone forms are in good agreement with expected pH changes by measured electrolysis rates, demonstrating that solvent electrolysis can be used to provide tunable, quantitative pH control within a microchannel. PMID:25379105

  16. Optical and electrochemical characteristics of sol-gel deposited tungsten oxide films: a comparison

    Microsoft Academic Search

    Nilgün Özer

    1997-01-01

    Tungsten oxide (WO3) films prepared by the sol-gel spin coating technique from a solution of tungsten oxychloride (S WO3) and for comparison from tungsten complex precursor (D WO3). Both types of films were analyzed by ellipsometry, Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), scanning electron microscopy (SEM) and cyclic voltammetry (CV). XRD studies showed that both films were amorphous.

  17. Structural and electrochemical properties of nanostructured nickel silicides by reduction and silicification of high-surface-area nickel oxide

    SciTech Connect

    Chen, Xiao [Laboratory of Advanced Materials and Catalytic Engineering, State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024 (China)] [Laboratory of Advanced Materials and Catalytic Engineering, State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024 (China); Zhang, Bingsen [Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society (Germany)] [Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society (Germany); Li, Chuang; Shao, Zhengfeng [Laboratory of Advanced Materials and Catalytic Engineering, State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024 (China)] [Laboratory of Advanced Materials and Catalytic Engineering, State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024 (China); Su, Dangsheng [Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society (Germany)] [Department of Inorganic Chemistry, Fritz Haber Institute of the Max Planck Society (Germany); Williams, Christopher T. [Department of Chemical Engineering, Swearingen Engineering Center, University of South Carolina (United States)] [Department of Chemical Engineering, Swearingen Engineering Center, University of South Carolina (United States); Liang, Changhai, E-mail: changhai@dlut.edu.cn [Laboratory of Advanced Materials and Catalytic Engineering, State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024 (China)] [Laboratory of Advanced Materials and Catalytic Engineering, State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024 (China)

    2012-03-15

    Graphical abstract: Nanostructured nickel silicides have been synthesized by reduction and silification of high-surface-area nickel oxide, and exhibited remarkably like-noble metal property, lower electric resistivity, and ferromagnetism at room temperature. Highlights: Black-Right-Pointing-Pointer NiSi{sub x} have been prepared by reduction and silification of high-surface-area NiO. Black-Right-Pointing-Pointer The structure of nickel silicides changed with increasing reaction temperature. Black-Right-Pointing-Pointer Si doping into nickel changed the magnetic properties of metallic nickel. Black-Right-Pointing-Pointer NiSi{sub x} have remarkably lower electric resistivity and like-noble metal property. -- Abstract: Nanostructured nickel silicides have been prepared by reduction and silicification of high-surface-area nickel oxide (145 m{sup 2} g{sup -1}) produced via precipitation. The prepared materials were characterized by nitrogen adsorption, X-ray diffraction, thermal analysis, FT-IR spectroscopy, scanning electron microscopy, transmission electron microscopy, magnetic and electrochemical measurements. The nickel silicide formation involves the following sequence: NiO (cubic) {yields} Ni (cubic) {yields} Ni{sub 2}Si (orthorhombic) {yields} NiSi (orthorhombic) {yields} NiSi{sub 2} (cubic), with particles growing from 13.7 to 21.3 nm. The nickel silicides are ferromagnetic at room temperature, and their saturation magnetization values change drastically with the increase of Si content. Nickel silicides have remarkably low electrical resistivity and noble metal-like properties because of a constriction of the Ni d band and an increase of the electronic density of states. The results suggest that such silicides are promising candidates as inexpensive yet functional materials for applications in electrochemistry as well as catalysis.

  18. The Muscle Oxidative Regulatory Response to Acute Exercise Is Not Impaired in Less Advanced COPD Despite a Decreased Oxidative Phenotype

    PubMed Central

    Hellwig, Valéry A. C. V.; Barreiro, Esther; Schols, Annemie M. W. J.; Gosker, Harry R.

    2014-01-01

    Already in an early disease stage, patients with chronic obstructive pulmonary disease (COPD) are confronted with impaired skeletal muscle function and physical performance due to a loss of oxidative type I muscle fibers and oxidative capacity (i.e. oxidative phenotype; Oxphen). Physical activity is a well-known stimulus of muscle Oxphen and crucial for its maintenance. We hypothesized that a blunted response of Oxphen genes to an acute bout of exercise could contribute to decreased Oxphen in COPD. For this, 28 patients with less advanced COPD (age 65±7 yrs, FEV1 59±16% predicted) and 15 age- and gender-matched healthy controls performed an incremental cycle ergometry test. The Oxphen response to exercise was determined by the measurement of gene expression levels of Oxphen markers in pre and 4h-post exercise quadriceps biopsies. Because exercise-induced hypoxia and oxidative stress may interfere with Oxphen response, oxygen saturation and oxidative stress markers were assessed as well. Regardless of oxygen desaturation and absolute exercise intensities, the Oxphen regulatory response to exercise was comparable between COPD patients and controls with no evidence of increased oxidative stress. In conclusion, the muscle Oxphen regulatory response to acute exercise is not blunted in less advanced COPD, regardless of exercise-induced hypoxia. Hence, this study provides further rationale for incorporation of exercise training as integrated part of disease management to prevent or slow down loss of muscle Oxphen and related functional impairment in COPD. PMID:24587251

  19. Tin oxide nanoparticles-polymer modified single-use sensors for electrochemical monitoring of label-free DNA hybridization

    Microsoft Academic Search

    Mihrican Muti; Filiz Kuralay; Arzum Erdem; Serdar Abaci; Tugrul Yumak; Ali Sina?

    2010-01-01

    In this study, SnO2 nanoparticles (SNPs)-poly(vinylferrocenium) (PVF+) modified single-use graphite electrodes were developed for electrochemical monitoring of DNA hybridization. The surfaces of polymer modified and polymer–SNP modified pencil graphite electrodes (PGEs) were firstly characterized by using SEM analysis. The electrochemical behaviours of these electrodes were also investigated using the differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. The

  20. Electrochemical cell

    DOEpatents

    Kaun, Thomas D. (New Lenox, IL)

    1984-01-01

    An improved secondary electrochemical cell is disclosed having a negative electrode of lithium aluminum, a positive electrode of iron sulfide, a molten electrolyte of lithium chloride and potassium chloride, and the combination that the fully charged theoretical capacity of the negative electrode is in the range of 0.5-1.0 that of the positive electrode. The cell thus is negative electrode limiting during discharge cycling. Preferably, the negative electrode contains therein, in the approximate range of 1-10 volume % of the electrode, an additive from the materials of graphitized carbon, aluminum-iron alloy, and/or magnesium oxide.

  1. In situ electrochemical synthesis of highly loaded zirconium nanoparticles decorated reduced graphene oxide for the selective determination of dopamine and paracetamol in presence of ascorbic acid.

    PubMed

    Ezhil Vilian, A T; Rajkumar, Muniyandi; Chen, Shen-Ming

    2014-03-01

    Highly loaded zirconium oxide (ZrO2) nanoparticles were supported on graphene oxide (ERGO/ZrO2) via an in situ, simple and clean strategy on the basis of the electrochemical redox reaction between zirconyl chloride and graphene oxide (ZrOCl2 and GO). The electrochemical measurements and surface morphology of the as prepared nanocomposite were studied using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and field emission scanning electron microscopy (FESEM). This ZrO2 decorated reduced graphene oxide nanocomposite modified GCE (ERGO/ZrO2) exhibits a prominent electrocatalytic activity toward the selective detection and determination of dopamine (DA) and paracetamol (PA) in presence of ascorbic acid (AA). The peaks of linear sweep voltammetry (LSV) for DA and PA oxidation at ERGO/ZrO2 modified electrode surface were clearly separated from each other when they co-existed in the physiological pH (pH 7.0) with a potential value of 140 mV (between AA and DA) and 330 mV (between AA and PA). It was, therefore, possible to simultaneously determine DA and PA in the samples at ERGO/ZrO2 nanocomposite modified GCE. Linear calibration curves were obtained for 9-237 ?M of PA and DA. The ERGO/ZrO2 nanocomposite electrode has been satisfactorily used for the determination of DA and PA in the presence of AA at pharmaceutical formulations in human urine samples with a linear range of 3-174 ?M. The proposed biosensor shows a wide linear range, low detection limit, good reproducibility and acceptable stability, providing a biocompatible platform for bio sensing and bio catalysis. PMID:24384145

  2. In vitro oxidation of fibrinogen promotes functional alterations and formation of advanced oxidation protein products, an inflammation mediator.

    PubMed

    Torbitz, Vanessa Dorneles; Bochi, Guilherme Vargas; de Carvalho, José Antônio Mainardi; Vaucher, Rodrigo de Almeida; da Silva, José Edson Paz; Moresco, Rafael Noal

    2015-06-01

    Fibrinogen (FB) is a soluble blood plasma protein and is a key molecule involved in coagulation. Oxidative modification of proteins, such as the formation of advanced oxidation protein products (AOPP), a heterogeneous family of protein compounds structurally modified and derived from oxidative stress, may be associated with the pathophysiology of a number of chronic inflammatory diseases. Therefore, the aim of this study was to determine whether the formation of this mediator of inflammation occurs from FB and whether its generation is associated with structural changes. Results of the present study suggest that the oxidation of FB may provoke the formation of AOPP, which in turn, may promote functional alterations in FB, thus causing changes in its structural domains and increasing its procoagulant activity. PMID:25502444

  3. Glucosamine-Anchored Graphene Oxide Nanosheets: Fabrication, Ultraviolet Irradiation, and Electrochemical Properties.

    PubMed

    Veerapandian, Murugan; Lévaray, Nicolas; Lee, Min-Ho; Giasson, Suzanne; Zhu, X X

    2015-07-15

    A biofunctionalized graphene oxide (GO) nanosheet with improved physicochemical properties is useful for electrocatalysis and sensor development. Herein, a new class of functionalized GO with a chemically anchored biomolecule glucosamine is developed. Structural and chemical analyses confirm the glucosamine anchoring. Ultraviolet irradiation transforms the surface chemistry of GO. Glucosamine-anchored GO nanosheets exhibit improved cyclic voltammetric and amperometric sensing activity toward the model redox probe, ruthenium(II) and N-acetylneuraminic acid, respectively. The biomolecular anchoring and ultraviolet irradiation helped to tune and enhance the properties of GO, which may find multiple applications in optimizing sensor platforms. PMID:26120929

  4. Synthesis and Electrochemical Properties of Nano Fiber Hollandite-Type Manganese Oxides Using a Hydrothermal Method

    NASA Astrophysics Data System (ADS)

    Kadoma, Yoshihiro; Akahira, Tatsuya; Fukuda, Tsubasa; Ui, Koichi; Kumagai, Naoaki

    2012-03-01

    Hollandite-type MnO2 and its Co-substituted samples have been synthesized by hydrothermal method from MnSO4, CoSO4 and K2S2O8 solutions. The hydrothermal products from MnSO4 and K2S2O8 solutions consisted of the hollandite-type [2 × 2] tunnel structure at 100°C-150°C for 12 h, which was transformed to pyrolusite-type [1 × 1] tunnel structure by hydrothermal treatment at 150°C for longer times of 24-48 h or at a higher temperature of 180°C. On the other hand, the hydrothermal products from MnSO4, CoSO4 and K2S2O8 solutions at 150°C-180°C for 12-48 h consisted of the hollandite-type MnO2 phase. The Co-substituted samples showed higher initial discharge capacity (180-200 mAh (g-oxide)-1) than that of non-substituted hollandite-type MnO2 (130-160 mAh (g-oxide)-1) at 50 mA g-1.

  5. Electrochemical studies of membranes, catalysts, and fuels for direct oxidation fuel cells

    NASA Astrophysics Data System (ADS)

    McGrath, Kimberly Michelle

    Over the past 15 years, the electrical performance of direct methanol fuel cells (DMFCs) has increased at least tenfold. While the DMFC has a theoretical energy density of 6094 W h/kg, only 1000-3200 W h/kg of this energy is realized in practice. Although most portable power applications only necessitate several W h/kg, performance and cost issues associated with polymer electrolyte membranes (PEMs), anode and cathode catalysts, system design, and operational considerations must be overcome for DMFCs to have a role in the methanol economy. Water management within a direct methanol fuel cell is critical to achieve optimal performance, especially at higher current densities where increased water production occurs. The semi-interpenetrating network composite membrane, poly(styrenesulfonic acid) poly(vinylidene fluoride) is shown to have dramatically decreased water flux due to electroosmotic drag compared to the conventional material, NafionRTM--117. In addition, a potentiometric method for screening new proton exchange membrane candidates is illustrated as a rapid method for determination of methanol crossover. Electrooxidation of other small hydrocarbon fuels, such as formic acid, methyl formate, ethylene glycol, and dimethyl oxalate were investigated in a direct oxidation fuel cell (DOFC). At room temperature, formic acid outperforms methanol by virtue of reduction in fuel crossover. Alternative catalyst systems for these fuels must be further investigated. Gold has a tolerance for methanol while promoting reduction of oxidation, and has proved to be a promising candidate as a cathode catalyst.

  6. Comparison study of electrochemical properties of porous zinc oxide/N-doped carbon and pristine zinc oxide polyhedrons

    NASA Astrophysics Data System (ADS)

    Zhou, Zhenfang; Zhang, Kun; Liu, Jinghao; Peng, Hongrui; Li, Guicun

    2015-07-01

    An in-situ calcination strategy has been developed for the synthesis of porous zinc oxide/N-doped carbon (ZnO/NC) polyhedrons, in which zeolitic imidazolate framework-8 (ZIF-8) serves as the precursor. The ZnO/NC polyhedrons with a hierarchical architecture possess a high specific surface area of 390.7 m2 g-1, high nitrogen content (19.99 at%), and robust pore structures. The porous N-doped carbon frameworks can not only increase the electronic conductivity of ZnO, but also provide interior space for the fast diffusion of Li+ ions and accommodate the volume variations during the charge and discharge cycles. When evaluated for lithium storage capacity, the hierarchical ZnO/NC polyhedrons exhibit high reversible discharge capacity (834.3 mAh g-1 at the initial low rate of 0.5C, 1C = 978 mA g-1), superior rate performance (399.2 mAh g-1 at 5C and 253.5 mAh g-1 at 10C), and excellent cycling stability (677.9 mAh g-1 at 1C after 400 cycles). The reasons are explored in terms of the well-confined primary nanocrystals (5 nm), and the finely constructed interconnected pores of the N-doped carbon networks, which facilitate the fast and effective transfer of Li+ ions and electrons, and accommodate the large volume expansions.

  7. Electrochemical Performance and Stability of the Cathode for Solid Oxide Fuel Cells: III. Role of volatile boron species on LSM/YSZ and LSCF

    SciTech Connect

    Zhou, Xiao Dong; Templeton, Jared W.; Zhu, Zihua; Chou, Y. S.; Maupin, Gary D.; Lu, Zigui; Brow, R. K.; Stevenson, Jeffry W.

    2010-09-02

    Boron oxide is a key component to tailor the softening temperature and viscosity of the sealing glass for solid oxide fuel cells. The primary concern regarding the use of boron containing sealing glasses is the volatility of boron species, which possibly results in cathode degradation. In this paper, we report the role of volatile boron species on the electrochemical performance of LSM/YSZ and LSCF cathodes at various SOFC operation temperatures. The transport rate of boron, ~ 3.24×10-12 g/cm2•sec was measured at 750°C with air saturated with 2.8% moisture. A reduction in power density was observed in cells with LSM/YSZ cathodes after introduction of the boron source to the cathode air stream. Partial recovery of the power density was observed after the boron source was removed. Results from post-test secondary ion mass spectroscopy (SIMS) analysis the partial recovery in power density correlated with partil removal of the deposited boron by the clean air stream. The presence of boron was also observed in LSCF cathodes by SIMS analysis, however the effect of boron on the electrochemical performance of LSCF cathode was negligible. Coverage of triple phase boundaries in LSM/YSZ was postulated as the cause for the observed reduction in electrochemical performance.

  8. Molecularly imprinted solid-phase extraction combined with electrochemical oxidation fluorimetry for the determination of methotrexate in human serum and urine

    NASA Astrophysics Data System (ADS)

    Chen, Suming; Zhang, Zhujun

    2008-06-01

    The method of synthesis and evaluation of molecularly imprinted polymers was reported. As a selective solid-phase extraction sorbent, the polymers were coupled with electrochemical fluorimetry detection for the efficient determination of methotrexate in serum and urine. Methotrexate was preconcentrated in the molecularly imprinted solid-phase extraction microcolumn packed with molecularly imprinted polymers, and then eluted. The eluate was detected by fluorescence spectrophotometer after electrochemical oxidation. The conditions of preconcentration, elution, electrochemical oxidation and determination were carefully studied. Under the selected experimental conditions, the calibration graph of the fluorescence intensity versus methotrexate concentration was linear from 4 × 10 -9 g mL -1 to 5 × 10 -7 g mL -1, and the detection limit was 8.2 × 10 -10 g mL -1 (3 ?). The relative standard deviation was 3.92% ( n = 7) for 1 × 10 -7 g mL -1 methotrexate. The experiments showed that the selectivity and sensitivity of fluorimetry could be greatly improved by the proposed method. This method has been successfully applied to the determination of methotrexate. At the same time, the binding characteristics of the polymers to the methotrexate were evaluated by batch and dynamic methods.

  9. pH-switchable electrochemical sensing platform based on chitosan-reduced graphene oxide/concanavalin a layer for assay of glucose and urea.

    PubMed

    Song, Yonghai; Liu, Hongyu; Tan, Hongliang; Xu, Fugang; Jia, Jianbo; Zhang, Lixue; Li, Zhuang; Wang, Li

    2014-02-18

    A facile and effective electrochemical sensing platform for the detection of glucose and urea in one sample without separation was developed using chitosan-reduced graphene oxide (CS-rGO)/concanavalin A (Con A) as a sensing layer. The CS-rGO/Con A with pH-dependent surface net charges exhibited pH-switchable response to negatively charged Fe(CN)6(3-). The principle for glucose and urea detection was essentially based on in situ pH-switchable enzyme-catalyzed reaction in which the oxidation of glucose catalyzed by glucose oxidase or the hydrolyzation of urea catalyzed by urease resulted in a pH change of electrolyte solution to give different electrochemical responses toward Fe(CN)6(3-). It was verified by cyclic voltammograms, differential pulse voltammograms, and electrochemical impedance spectroscopy. The resistance to charge transfer or amperometric current changed proportionally toward glucose concentration from 1.0 to 10.0 mM and urea concentration from 1.0 to 7.0 mM. On the basis of human serum experiments, the sensing platform was proved to be suitable for simultaneous assay of glucose and urea in a practical biosystem. This work not only gives a way to detect glucose and urea in one sample without separation but also provides a potential strategy for the detection of nonelectroactive species based on the enzyme-catalyzed reaction and pH-switchable biosensor. PMID:24502773

  10. Fabrication and electrochemical treatment application of a novel lead dioxide anode with superhydrophobic surfaces, high oxygen evolution potential, and oxidation capability.

    PubMed

    Zhao, Guohua; Zhang, Yonggang; Lei, Yanzhu; Lv, Baoying; Gao, Junxia; Zhang, Yanan; Li, Dongming

    2010-03-01

    A novel PbO(2) electrode with a high oxygen evolution potential (OEP) and excellent electrochemical oxidation performance is prepared to improve the traditional PbO(2) electrode, which is modified by changing the microstructure and wetting ability. A middle layer of TiO(2) nanotubes (NTs) with a large surface area is introduced on Ti substrate, and a small amount of Cu is predeposited at the bottom of TiO(2)-NTs. The modification will improve the electrochemical performance by enhancing the loading capacity of PbO(2) and the combination between PbO(2) and Ti substrate. The hydrophilic surface becomes highly hydrophobic by adding fluorine resin. The improved PbO(2) electrode exhibits a similar morphology, surface wetting ability, high OEP, and electrochemical performance with boron-doped diamond film (BDD) electrode. However, the physical resistance of the PbO(2) electrode is much lower than that of BDD, exhibiting higher conductivity. The hydroxyl radical utilization is significantly enhanced, resulting in a higher oxidation rate and higher removal for 2,4-dichlorophenoxyacetic acid. PMID:20180602

  11. A wind-powered BDD electrochemical oxidation process for the removal of herbicides.

    PubMed

    Souza, F L; Lanza, M R V; Llanos, J; Sáez, C; Rodrigo, M A; Cañizares, P

    2015-08-01

    In the search for greener treatment technologies, this work studies the coupling of a wind turbine energy supply with an electrolytic cell (CWTEC device) for the remediation of wastewater polluted with pesticide 2,4-dichlorophenoxyacetic acid (2,4-D). The discontinuous and unforeseeable supply of energy is the main challenge inspiring this new proposal, which aims at reducing the environmental impact of electrolytic treatment by using a green energy supply. The results obtained using the coupled technologies are compared with those obtained by powering the electrolyser with a traditional power supply with a similar current intensity. The mineralisation of wastewater can be accomplished independently of how the electrolytic cell is powered, although differences in performance are clearly observed in the total organic carbon (TOC) and 2,4-D decays. These changes can be explained in terms of the changing profile of the current intensity, which influences the concentrations of the oxidants produced and thereby the mediated electrolytic process. PMID:25950835

  12. Fabrication of ordered mesoporous carbon film supporting vanadium oxides for electrochemical supercapacitor

    NASA Astrophysics Data System (ADS)

    Zhao, Chunxia; Li, Junshen; Cao, Jinqiao; Chen, Wen

    2015-11-01

    Ordered mesoporous carbon film supporting vanadium oxide nanoparticles has been synthesized via ultrasound-assistant impregnation method with ordered mesoporous carbon C-FDU15 film as the host and V2O5 sol as the guest precursor. The hybrids exhibit type IV sorption isotherms with H2 hysteresis loop, indicating the well-retained characteristics of ordered mesoporous structure. The capacitance of the materials is enhanced with V2O5 loading. Particularly, the hybrids with 32.26 wt.% V2O5 loading yield an important capacitance of 128 F/g in 1 mol/L KNO3 electrolyte under a potential range from -0.6 V to 0.6 V. The improved specific capacitance of the hybrids is proposed to be the combination of the double-layer capacitance of ordered porous structure and the pseudocapacitance derived from V2O5.

  13. Electrochemical Oxidation and Determination of Oxalic Acid at an Exfoliated Graphite-Polystyrene Composite Electrode

    PubMed Central

    Manea, Florica; Radovan, Ciprian; Corb, Ioana; Pop, Aniela; Burtica, Georgeta; Malchev, Plamen; Picken, Stephen; Schoonman, Joop

    2007-01-01

    An exfoliated graphite-polystyrene composite electrode was evaluated as an alternative electrode in the oxidation and the determination of oxalic acid in 0.1 M Na2SO4 supporting electrolyte. Using CV, LSV, CA procedures, linear dependences I vs. C were obtained in the concentrations range of oxalic acid between 0.5 to 3 mM, with LOD =0.05 mM, and recovery degree of 98%, without need of surface renewing between successive runs. The accuracy of the methods was evaluated as excellent comparing the detection results with that obtained using conventional KMnO4 titration method. In addition, the apparent diffusion coefficient of oxalic acid D was found to be around 2.89 · 10-8 cm2·s-1 by CA and CV.

  14. The polymerization and electrochemical characterization of polypyrrole and polypyrrole/poly(ethylene oxide)pyrrole copolymers

    NASA Astrophysics Data System (ADS)

    Huntoon, Trey William Stevens

    1998-11-01

    The work contained within this document discusses the polymerization and subsequent characterization of Polypyrrole based electrodes for lithium batteries. Polypyrrole and Polypyrrole/polyethyloxy copolymers were compared and contrasted in an attempt to show the superior kinetics of the copolymer electrode. It was found that the diffusion of dopant ions across the electrode and electrolyte interface was increased by on order of magnitude in the copolymer sample. It was also found that the reversibility of the Polypyrrole electrode was greater than that of the copolymer electrode. While the diffusion coefficient of the copolymer electrode was altered to be comparable to that of the transition metal oxide cathodes in production today, the capacity of the copolymer material is still too low to be considered as an alternative cathode material in the lithium battery industry.

  15. Electrochemical absorption and oxidation of hydrogen on palladium alloys with platinum, gold and rhodium.

    PubMed

    ?ukaszewski, Mariusz; Hubkowska, Katarzyna; Czerwi?ski, Andrzej

    2010-11-21

    Thin layers of Pd and its alloys with Pt, Au and Rh were prepared by electrodeposition on a Au substrate. Hydrogen electrosorption by the obtained electrodes was studied in 0.5 M H(2)SO(4) solution using cyclic voltammetry and chronoamperometry. The influence of the alloying process on selected thermodynamic (the amount of absorbed hydrogen, the stability of the ?-phase, the extent of the absorption/desorption hysteresis) and kinetic aspects (the rate of hydrogen absorption and absorbed hydrogen oxidation) of hydrogen absorption and desorption was examined. It was found that the addition of the non-absorbing elements to Pd results in faster kinetics of the hydrogen electrosorption process and a smaller absorption/desorption hysteresis. PMID:20890504

  16. Novel Fibrous Catalyst in Advanced Oxidation of Photographic Processing Effluents

    Microsoft Academic Search

    ZHUXIAN YANG; VERA V. ISHTCHENKO; KATHERINE D. HUDDERSMAN

    2006-01-01

    A novel fibrous catalyst was used to destroy the pollutants in Kodak Non-Silver-Bearing (NSB) photographic processing effluents with high chemical oxygen demand (COD) value. The oxidation activity of the catalyst was evaluated in terms of COD reduction of the effluent. The effects of concentrations of hydrogen peroxide and effluent, amount of catalyst, reaction time and temperature on the COD reduction

  17. Solid state electrochemical current source

    DOEpatents

    Potanin, Alexander Arkadyevich (Sarov, RU); Vedeneev, Nikolai Ivanovich (Sarov, RU)

    2002-04-30

    A cathode and a solid state electrochemical cell comprising said cathode, a solid anode and solid fluoride ion conducting electrolyte. The cathode comprises a metal oxide and a compound fluoride containing at least two metals with different valences. Representative compound fluorides include solid solutions of bismuth fluoride and potassium fluoride; and lead fluoride and potassium fluoride. Representative metal oxides include copper oxide, lead oxide, manganese oxide, vanadium oxide and silver oxide.

  18. Advanced oxidation processes for degradation of 2,4-dichlo- and 2,4-dimethylphenol

    Microsoft Academic Search

    Marina Trapido; Yelena Veressinina; Rein Munter

    1998-01-01

    The efficiency of different advanced oxidation processes for degradation of two phenols, 2,4-dimethylphenol (2,4-DMP) and 2,4-dichlorophenol (2,4-DCP), has been under study. Advanced oxidation processes, especially the Fe{sup 2+}\\/HâOâ\\/ultraviolet (UV) system, were found to be effective in decomposing phenols and chlorophenols. The degradation rate for 2,4-DCP followed the order, HâOâ\\/Fe{sup 2+}\\/UV > HâOâ\\/Fe{sup 2+} > Oâ\\/ultrasound (US) > Oâ ⥠Oâ\\/UV

  19. Removal of residual pharmaceuticals from aqueous systems by advanced oxidation processes

    Microsoft Academic Search

    Maria Klavarioti; Dionissios Mantzavinos; Despo Kassinos

    2009-01-01

    Over the past few years, pharmaceuticals are considered as an emerging environmental problem due to their continuous input and persistence to the aquatic ecosystem even at low concentrations. Advanced oxidation processes (AOPs) are technologies based on the intermediacy of hydroxyl and other radicals to oxidize recalcitrant, toxic and non-biodegradable compounds to various by-products and eventually to inert end-products. The environmental

  20. Effect of advanced oxidation processes on the toxicity of municipal landfill leachates

    Microsoft Academic Search

    B. Slomczynska; J. Wasowski; T. Slomczynski

    The aim of the present study was to assess the effect of advanced oxidation processes (AOPs) (oxidation ozone and peroxide\\/ozone) on the toxicity of leachates from municipal landfill for Warsaw, Poland, using a battery of tests. AOPs used to pre-treat leachates were carried out in laboratory conditions after their coagulation with the use of FeCl3. The effects of the pre-treatment

  1. Degradation of RDX by various advanced oxidation processes: I. Reaction rates

    Microsoft Academic Search

    Purnendu Bose; William H. Glaze; D. Scott Maddox

    1998-01-01

    1, 3, 5-trinitrotriazacyclohexane (C3H6O6N6) or RDX is a heterocyclic nitramine compound that has been widely used as an explosive since the early 1900s. There is substantial interest in removing this compound from groundwater and other environmental media. Advanced oxidation processes (AOPs) are currently being tested as a treatment process for this compound. In this research five types of oxidation processes

  2. Treatment of statin compounds by advanced oxidation processes: Kinetic considerations and destruction mechanisms

    Microsoft Academic Search

    Behnaz Razavi; Weihua Song; Hanoz Santoke; William J. Cooper

    2011-01-01

    This study examined the use of advanced oxidation\\/reduction processes (AO\\/RPs) for the destruction of cholesterol lowering statin pharmaceuticals. AO\\/RPs which utilize the oxidizing hydroxyl radical (OH) and reducing aqueous electron (e?aq), to degrade chemical contaminants are alternatives to traditional water treatment methods, and are alternatives as water reuse becomes more generally implemented. Four major statin pharmaceuticals, fluvastatin, lovastatin, pravastatin and

  3. Electrochemical reduction of silver vanadium phosphorous oxide, Ag(2)VO(2)PO(4): the formation of electrically conductive metallic silver nanoparticles.

    PubMed

    Takeuchi, Esther S; Marschilok, Amy C; Tanzil, Kevin; Kozarsky, Eric S; Zhu, Shali; Takeuchi, Kenneth J

    2009-10-27

    As a cathode material, silver vanadium phosphorous oxide (Ag(2)VO(2)PO(4)) displays several notable electrochemical properties: large capacity, high current capability, and an effective delivery of high current pulses. These cell performance characteristics can be attributed to the presence of silver nanoparticles formed in-situ during the electrochemical reduction of Ag(2)VO(2)PO(4). Specifically, changes in the composition and structure of Ag(2)VO(2)PO(4) with reduction, especially the formation of silver nanoparticles, are detailed to rationalize a 15,000 fold increase in conductivity with initial discharge, which can be related to the power characteristics associated with Ag(2)VO(2)PO(4) cathodes in primary lithium batteries. PMID:20161435

  4. Electrochemical reduction of silver vanadium phosphorous oxide, Ag2VO2PO4: the formation of electrically conductive metallic silver nanoparticles

    PubMed Central

    Takeuchi, Esther S.; Marschilok, Amy C.; Tanzil, Kevin; Kozarsky, Eric S.; Zhu, Shali; Takeuchi, Kenneth J.

    2009-01-01

    As a cathode material, silver vanadium phosphorous oxide (Ag2VO2PO4) displays several notable electrochemical properties: large capacity, high current capability, and an effective delivery of high current pulses. These cell performance characteristics can be attributed to the presence of silver nanoparticles formed in-situ during the electrochemical reduction of Ag2VO2PO4. Specifically, changes in the composition and structure of Ag2VO2PO4 with reduction, especially the formation of silver nanoparticles, are detailed to rationalize a 15,000 fold increase in conductivity with initial discharge, which can be related to the power characteristics associated with Ag2VO2PO4 cathodes in primary lithium batteries. PMID:20161435

  5. Electrochemical fabrication of capacitors

    DOEpatents

    Mansour, Azzam N. (Fairfax Sta., VA); Melendres, Carlos A. (Lemont, IL)

    1999-01-01

    A film of nickel oxide is anodically deposited on a graphite sheet held in osition on an electrochemical cell during application of a positive electrode voltage to the graphite sheet while exposed to an electrolytic nickel oxide solution within a volumetrically variable chamber of the cell. An angularly orientated x-ray beam is admitted into the cell for transmission through the deposited nickel oxide film in order to obtain structural information while the film is subject to electrochemical and in-situ x-ray spectroscopy from which optimum film thickness, may be determined by comparative analysis for capacitor fabrication purposes.

  6. Oxone\\/Co 2+ oxidation as an advanced oxidation process: Comparison with traditional Fenton oxidation for treatment of landfill leachate

    Microsoft Academic Search

    Jianhui Sun; Xiaoyan Li; Jinglan Feng; Xiaoke Tian

    2009-01-01

    In this paper, the application of Fenton and Oxone\\/Co2+ oxidation processes for landfill leachate treatment was investigated. The removal of the chemical oxygen demand (COD), suspended substances (SS) and the color of the landfill leachate by Fenton oxidation to that by Oxone\\/Co2+ oxidation were compared under optimal operational conditions. For Fenton oxidation process, the optimal conditions were determined as: [H2O2]=80mmol

  7. Electrochemical activity evaluation of chemically damaged carbon nanotube with palladium nanoparticles for ethanol oxidation

    NASA Astrophysics Data System (ADS)

    Ahmed, Mohammad Shamsuddin; Jeon, Seungwon

    2015-05-01

    The carbon nanotube (CNT) has unique electrical and structural properties due to it's sp2 ?-conjugative structure that leads to the higher electrocatalysis. The ?-conjugative structure, that allows the CNT interact with various compounds and metal nanoparticles (NPs) through ?-? electronic interaction. However, the damage of ?-conjugative sidewall of CNT that can be hinder the electrocatalytic activity has found. For this study, the CNT, as base material, has been prepared through a conventional acid treatment method up to 15 h; the higher degree of sidewall damage has been observed in last 5 h during treatment period. The short and long term acid treated (denoted as CNT and CNT-COOH, respectively) CNTs have been subsequently fabricated with palladium NPs (denoted as CNT/Pd and CNT-Pd, respectively) and employed as ethanol oxidation reaction (EOR) catalysts. The CNT-Pd displays a poor electrocatalytic performance towards EOR than that of CNT/Pd due to the damage of ?-conjugative sidewall. The kinetic parameters including poisoning tolerance have also been hampered by the surface damage. The CNT/Pd (?3.3 folds) and CNT-Pd (?1.5 folds) are express higher electrocatalytic activity and poisoning tolerance than that of Pd/C while Pd mass loading remains in the same amount.

  8. Effect of graphene oxide on the structural and electrochemical behavior of polypyrrole deposited on cotton fabric

    NASA Astrophysics Data System (ADS)

    Yaghoubidoust, Fatemeh; Wicaksono, Dedy H. B.; Chandren, Sheela; Nur, Hadi

    2014-10-01

    Improving the electrical response of polypyrrole-cotton composite is the key issue in making flexible electrode with favorable mechanical strength and large capacitance. Flexible graphene oxide/cotton (GO/Cotton) composite has been prepared by dipping pristine cotton in GO ink. The composite‘s surface was further modified with polypyrrole (Ppy) via chemical polymerization to obtain Ppy/GO/Cotton composite. The composite was characterized using SEM, FTIR and XRD measurements, while the influence of GO in modifying the physicochemical properties of the composite was also examined using TG and cyclic voltammetry. The achieved mean particle size for Ppy/Cotton, Ppy/GO/Cotton and GO estimated using Scherrer formula are 58, 67 and 554 nm, respectively. FTIR spectra revealed prominent fundamental absorption bands in the range of 1400-1800 cm-1. The increased electrical conductivity as much as 2.2 × 10-1 S cm-1 for Ppy/GO/Cotton composite measured by complex impedance, is attributed to the formation of continuous conducting network. The partial reduction of GO on the surface of cotton (GO/Cotton) during chemical polymerization can also affect the conductivity. This simple, economic and environmental-friendly preparation method may contribute towards the controlled growth of quality and stable Ppy/GO/Cotton composites for potential applications in microwave attenuation, energy storage system, static electric charge dissipation and electrotherapy.

  9. Chemical, structural, and electrochemical characterization of 5 V spinel and complex layered oxide cathodes of lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Tiruvannamalai Annamalai, Arun Kumar

    2007-12-01

    Lithium ion batteries have revolutionized the portable electronics market since their commercialization first by Sony Corporation in 1990. They are also being intensively pursued for electric and hybrid electric vehicle applications. Commercial lithium ion cells are currently made largely with the layered LiCoO 2 cathode. However, only 50% of the theoretical capacity of LiCoO 2 can be utilized in practical cells due to the chemical and structural instabilities at deep charge as well as safety concerns. These drawbacks together with the high cost and toxicity of Co have created enormous interest in alternative cathodes. In this regard, spinel LiMn2O4 has been investigated widely as Mn is inexpensive and environmentally benign. However, LiMn 2O4 exhibits severe capacity fade on cycling, particularly at elevated temperatures. With an aim to overcome the capacity fading problems, several cationic substitutions to give LiMn2-yMyO 4 (M = Cr, Fe, Co, Ni, and Cu) have been pursued in the literature. Among the cation-substituted systems, LiMn1.5Ni0.5O 4 has become attractive as it shows a high capacity of ˜ 130 mAh/g (theoretical capacity: 147 mAh/g) at around 4.7 V. With an aim to improve the electrochemical performance of the 5 V LiMn 1.5Ni0.5O4 spinel oxide, various cation-substituted LiMn1.5-yNi0.5-zMy+zO4 (M = Li, Mg, Fe, Co, and Zn) spinel oxides have been investigated by chemical lithium extraction. The cation-substituted LiMn1.5-yNi0.5-zM y+zO4 spinel oxides exhibit better cyclability and rate capability in the 5 V region compared to the unsubstituted LiMn1.5Ni 0.5O4 cathodes although the degree of manganese dissolution does not vary significantly. The better electrochemical properties of LiMn 1.5-yNi0.5-zMy+zO4 are found to be due to a smaller lattice parameter difference among the three cubic phases formed during the charge-discharge process. In addition, while the spinel Li1-xMn1.58Ni0.42O4 was chemically stable, the spinel Li1-xCo2O4 was found to exhibit both proton insertion and oxygen loss at deep lithium extraction due to the chemical instability arising from a overlap of the Co3+/4+:3d band on the top of the O2-:2p band. The irreversible oxygen loss during the first charge and the consequent reversible capacities of the solid solutions between Li[Li1/3Mn 2/3]O2 and Li[Co1-yNiy]O2 has been found to be determined by the amount of lithium in the transition metal layer of the O3 type layered structure. The lithium content in the transition metal layer is, however, sensitively influenced by the tendency of Ni 3+ to get reduced to Ni2+ and the consequent volatilization of lithium during synthesis. Moreover, high Mn4+ content causes a decrease in oxygen mobility and loss. In addition, the chemically delithiated samples were found to adopt either the parent O3 type structure or the new P3 or O1 type structures depending upon the composition and synthesis temperature of the parent samples and the proton content inserted into the delithiated sample. In essence, the chemical and structural stabilities and the electrochemical performance factors of the layered (1-z) Li[Li1/3 Mn2/3]O2 · (z) Li[Co1-yNi y]O2 solid solution cathodes are found to be maximized by optimizing the contents of the various ions.

  10. Treatment of petroleum refinery sourwater by advanced oxidation processes

    Microsoft Academic Search

    Alessandra Coelho; Antonio V. Castro; Márcia Dezotti; G. L. Sant’Anna

    2006-01-01

    The performance of several oxidation processes to remove organic pollutants from sourwater was investigated. Sourwater is a specific stream of petroleum refineries, which contains slowly biodegradable compounds and toxic substances that impair the industrial biological wastewater treatment system. Preliminary experiments were conducted, using the following processes: H2O2, H2O2\\/UV, UV, photocatalysis, ozonation, Fenton and photo-Fenton. All processes, except Fenton and photo-Fenton,

  11. Electrochemical oxidation of electrodialysed reverse osmosis concentrate on Ti/Pt-IrO2, Ti/SnO2-Sb and boron-doped diamond electrodes.

    PubMed

    Bagastyo, Arseto Y; Batstone, Damien J; Rabaey, Korneel; Radjenovic, Jelena

    2013-01-01

    Reverse osmosis concentrate from wastewater reclamation contains biorefractory trace organic contaminants that may pose environmental or health hazard. Due to its high conductivity, electrochemical oxidation of brine requires low voltage which is energetically favourable. However, the presence of chloride ions may lead to the formation of chlorinated by-products, which are likely to exert an increased toxicity and persistence to further oxidation than their non-chlorinated analogues. Here, the performance of Ti/Pt-IrO(2), Ti/SnO(2)-Sb and Si/BDD anodes was evaluated for the electrochemical oxidation of ROC in the presence of chloride, nitrate or sulfate ions (0.05 M sodium salts). In order to investigate the electrooxidation of ROC with nitrate and sulfate ions as dominant ion mediators, chloride ion concentration was decreased 10 times by electrodialytic pretreatment. The highest Coulombic efficiency for chemical oxygen demand (COD) removal was observed in the presence of high chloride ions concentration for all anodes tested (8.3-15.9%). Electrooxidation of the electrodialysed concentrate at Ti/SnO(2)-Sb and Ti/Pt-IrO(2) electrodes exhibited low dissolved organic carbon (DOC) (i.e. 23 and 12%, respectively) and COD removal (i.e. 37-43 and 6-22%, respectively), indicating that for these electrodes chlorine-mediated oxidation was the main oxidation mechanism, particularly in the latter case. In contrast, DOC removal for the electrodialysed concentrate stream was enhanced at Si/BDD anode in the presence of SO(4)(2-) (i.e. 51%) compared to NO(3)(2-) electrolyte (i.e. 41%), likely due to the contribution of SO(4)(·-) and S(2)O(8)(2-) species to the oxidative degradation. Furthermore, decreased concentration of chloride ions lead to a lower formation of haloacetic acids and trihalomethanes at all three electrodes tested. PMID:23137830

  12. Dietary advanced lipid oxidation endproducts are risk factors to human health.

    PubMed

    Kanner, Joseph

    2007-09-01

    Lipid oxidation in foods is one of the major degradative processes responsible for losses in food quality. The oxidation of unsaturated fatty acids results in significant generation of dietary advanced lipid oxidation endproducts (ALEs) which are in part cytotoxic and genotoxic compounds. The gastrointestinal tract is constantly exposed to dietary oxidized food compounds, after digestion a part of them are absorbed into the lymph or directly into the blood stream. After ingestion of oxidized fats animals and human have been shown to excrete in urine increase amounts of malondialdehyde but also lipophilic carbonyl compounds. Oxidized cholesterol in the diet was found to be a source of oxidized lipoproteins in human serum. Some of the dietary ALEs, which are absorbed from the gut to the circulatory system, seems to act as injurious chemicals that activate an inflammatory response which affects not only circulatory system but also organs such as liver, kidney, lung, and the gut itself. We believe that repeated consumption of oxidized fat in the diet poses a chronic threat to human health. High concentration of dietary antioxidants could prevent lipid oxidation and ALEs generation not only in foods but also in stomach condition and thereby potentially decrease absorption of ALEs from the gut. This could explains the health benefit of diets containing large amounts of dietary antioxidants such those present in fruits and vegetables, or products such as red-wine or tea consuming during the meal. PMID:17854006

  13. Advanced Oxidation Protein Products as Novel Mediators of Inflammation and Monocyte Activation in Chronic Renal Failure1, 2

    Microsoft Academic Search

    Veronique Witko-Sarsat; Miriam Friedlander; Thao Nguyen Khoa; Chantal Capeillere-Blandin; Anh Thu Nguyen; Sandrine Canteloup; Jean-Michel Dayer; Paul Jungers; Tilman Drueke; Beatrice Descamps-Latscha

    We previously demonstrated the presence of advanced oxidation protein products (AOPP), a novel marker of oxidative stress in the plasma of uremic patients receiving maintenance dialysis. The present study in a cohort of 162 uremic patients showed that plasma concentrations of AOPP increased with progression of chronic renal failure and were closely related to advanced glycation end products (AGE)-pentosidine (r

  14. Capacitive and Oxidant Generating Properties of Black-Colored TiO2 Nanotube Array Fabricated by Electrochemical Self-Doping.

    PubMed

    Kim, Choonsoo; Kim, Seonghwan; Lee, Jaehan; Kim, Jiye; Yoon, Jeyong

    2015-04-15

    Recently, black-colored TiO2 NTA (denoted as black TiO2 NTA) fabricated by self-doping of TiO2 NTA with the amorphous phase led to significant success as a visible-light-active photocatalyst. This enhanced photocatalytic activity is largely attributed to a higher charge carrier density as an effect of electrochemical self-doping resulting in a higher optical absorbance and lower transport resistance. Nevertheless, the potential of black TiO2 NTA for other electrochemical applications, such as a supercapacitor and an oxidant-generating anode, has not been fully investigated. Here, we report the capacitive and oxidant generating properties of black TiO2 NTA. The black TiO2 NTA exhibited significantly a high value for areal capacitance with a good rate capability and novel electrocatalytic activity in generating (•)OHs and Cl2 compared to pristine TiO2 NTA with the anatase phase. This study suggests that the black TiO2 NTA be applied as a supercapacitor and an oxidant generating anode. PMID:25793300

  15. Impact of CuO nanoleaves on MWCNTs/GCE nanocomposite film modified electrode for the electrochemical oxidation of folic acid

    NASA Astrophysics Data System (ADS)

    Manoj, D.; Ranjith Kumar, D.; Santhanalakshmi, J.

    2012-09-01

    The salient features of the present work focus on the synthesis of CuO nanoleaves by alcoholic reduction of Cu(II) chloride in the presence of poly(diallyldimethylammonium chloride) (PDDA) for the application of folic acid oxidation in simulated body fluid environment. PDDA-assisted polyol process allows a conventional impregnation method for the formation of CuO with well-defined leaf-like structure. The structure and morphology of the CuO nanoleaves were characterized by Fourier-transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) analysis. Field emission scanning electron microscope (FESEM) image confirms the formations of CuO with leaf-like morphology and branched side edges. The average size of the resultant CuO nanoleaves was calculated to be 400 nm in length and 150 nm in width. The electrochemical performance of the CuONs/MWCNTs/GCE nanocomposite modified electrode was characterized by cyclic voltammetric (CV) studies. The CuONs/MWCNTs/GCE nanocomposite modified electrode shows good electrochemical activity and it was also found that it possessed prominent electrocatalytic activity toward the oxidation of folic acid with as high a sensitivity as 3.35 ?A/?M and a low detection limit (3 ?) of 15.2 nM (S/N = 3). Besides, the CuO nanocomposite modified electrode lowers the over potential of folic acid oxidation than the unmodified electrodes.

  16. Innovative technical advances in the application of regenerative thermal oxidizers

    SciTech Connect

    Grzanka, R.; Truppi, T.

    1999-07-01

    Regenerative Thermal Oxidizers (RTOs) have been applied in industry for over twenty (20) years to reduce the emissions of Volatile Organic compounds (VOCs) into the atmosphere from industrial process emissions. The Clean Air Act and its amendments have established a regulatory framework setting standards for allowable levels of VOC emissions. Several forces are driving the increasing use and acceptance of this technology: (1) High efficiency and increasing stringent standards require higher destruction efficiency; (2) Low operating cost and control of emission streams with less VOCs (therefore, less fuel value) causing higher use of natural gas for combustion; (3) Low NO{sub x}--the overlapping concern of NO{sub x} generation from the combustion process; (4) Low process upsets with improved productivity of industrial process require continuous integration of VOC abatement equipment; and (5) Reduced capital cost--capital cost criteria is $/ton of VOC abated. The latest development in RTO technology is the Single Can Oxidizer (SCO). This regenerative thermal oxidizer is the accumulation of developments in many subsystems of RTOs, combined with a dramatic new configuration. Several features of the system offer unique benefits to industrial end users: (1) Single can configuration gives reduced weight, material usage, and cost; (2) Rotary valve design gives smooth operation, and low pressure fluctuations; (3) Structured block heat recovery media reduces pressure drop, and lowers HP/operating cost; and (4) SMART system lowers NO{sub x} output/reduced operation cost. This paper will present a discussion of the features listed above. In addition, it will provide analytical documentation of test results for a full scale commercial unit.

  17. TiO2-Based Advanced Oxidation Nanotechnologies For Water Purification And Reuse

    EPA Science Inventory

    TiO2 photocatalysis, one of the UV-based advanced oxidation technologies (AOTs) and nanotechnologies (AONs), has attracted great attention for the development of efficient water treatment and purification systems due to the effectiveness of TiO2 to generate ...

  18. Synthetic endocrine disruptors in the environment and water remediation by advanced oxidation processes

    Microsoft Academic Search

    Isil Gültekin; Nilsun H. Ince

    2007-01-01

    The present study is an overview of the literature on classes and types of compounds described as “endocrine disruptors” and their treatability in water by advanced oxidation processes, which generate hydroxyl radicals in water. The review is limited to details of the destruction of three classes of endocrine disruptors, namely bisphenols, alkylphenols and phthalates, which are among the most highly

  19. Advances in the growth and characterization of magnetic, ferroelectric, and multiferroic oxide thin films

    Microsoft Academic Search

    L. W. Martin; Y.-H. Chu; R. Ramesh

    2010-01-01

    The growth and characterization of functional oxide thin films that are ferroelectric, magnetic, or both at the same time are reviewed. The evolution of synthesis techniques and how advances in in situ characterization have enabled significant acceleration in improvements to these materials are described. Methods for enhancing the properties of functional materials or creating entirely new functionality at interfaces are

  20. Degradation of Aqueous Pharmaceuticals by Ozonation and Advanced Oxidation Processes: A Review

    Microsoft Academic Search

    Keisuke Ikehata; Naeimeh Jodeiri Naghashkar; Mohamed Gamal El-Din

    2006-01-01

    A vast number of pharmaceuticals have been detected in surface water and drinking water around the world, which indicates their ineffective removal from water and wastewater using conventional treatment technologies. Concerns have been raised over the potential adverse effects of pharmaceuticals on public health and aquatic environment. Among the different treatment options, ozonation and advanced oxidation processes are likely promising

  1. DEMONSTRATION OF THE HIPOX ADVANCED OXIDATION TECHNOLOGY FOR THE TREATMENT OF MTBE-CONTAMINATED GROUNDWATER

    EPA Science Inventory

    The HiPOx technology is an advanced oxidation process that incorporates high-precision delivery of ozone and hydrogen peroxide to chemically destroy organic contaminants with the promise of minimizing bromate formation. A MTBE-contaminated groundwater from the Ventura County Nava...

  2. DEMONSTRATION OF THE HIPOX ADVANCED OXIDATION TECHNOLOGY FOR THE TREATMENT OF MTBE-CONTAMINATED GROUNDWATER

    EPA Science Inventory

    The HiPOx technology is an advanced oxidation process that incorporates high-precision delivery of ozone and hydrogen peroxide to chemically destroy organic contaminants with the promise of minimizing bromate formation. A MTBE-contaminated groundwater from the Ventura County Nav...

  3. The Cost Evaluation of Advanced Oxidation Processes in Laboratory and Pilot-Scale Experiments

    Microsoft Academic Search

    Marina Krichevskaya; Deniss Klauson; Elina Portjanskaja; Sergei Preis

    2011-01-01

    The present level of the development of water\\/wastewater treatment methods, including advanced oxidation processes, allows removal of pollutants of wide spectrum under no question. However, the overall process cost and, especially, associated energy consumption are of increased importance. The present review presents the energy cost calculations made for the pollutants removal reported in more than forty publications for over the

  4. Degradation of chlorophenols by means of advanced oxidation processes: a general review

    Microsoft Academic Search

    Marc Pera-Titus; Verónica Garc??a-Molina; Miguel A Baños; Jaime Giménez; Santiago Esplugas

    2004-01-01

    Advanced oxidation processes (AOPs) constitute a promising technology for the treatment of wastewaters containing non-easily removable organic compounds. Chlorophenols (CPs) are a group of special interest due to their high toxicity and low biodegradability. Data concerning the degradation of CPs by means of AOPs reported during the period 1995–2002 are evaluated in this work. Among the AOPs, the following techniques

  5. Combining Advanced Oxidation Processes: Assessment Of Process Additivity, Synergism, And Antagonism

    Microsoft Academic Search

    Robert W. Peters; M. P. Sharma; Yusuf Gbadebo Adewuyi

    2007-01-01

    This paper addresses the process interactions from combining integrated processes (such as advanced oxidation processes (AOPs), biological operations, air stripping, etc.). AOPs considered include: Fenton's reagent, ultraviolet light, titanium dioxide, ozone (O), hydrogen peroxide (HO), sonication\\/acoustic cavitation, among others. A critical review of the technical literature has been performed, and the data has been analyzed in terms of the processes

  6. Application of Ozone Involving Advanced Oxidation Processes to Remove Some Pharmaceutical Compounds from Urban Wastewaters

    Microsoft Academic Search

    Fernando J. Beltrán; Almudena Aguinaco; Juan F. García-Araya

    2012-01-01

    Different UVA radiation and advanced oxidation systems, most of them involving ozone, have been applied to remove mixtures of three contaminants of pharmaceutical type: diclofenac (DCF), sulfamethoxazole (SMT) and caffeine (CFF), both in ultrapure and secondary treated wastewater. The influence of the water matrix has been studied in terms of individual compound concentration and TOC removal. Also, biodegradability of the

  7. Kinetics and mechanism of advanced oxidation processes (AOPs) in degradation of ciprofloxacin in water

    Microsoft Academic Search

    Taicheng An; Hai Yang; Guiying Li; Weihua Song; William J. Cooper; Xiangping Nie

    2010-01-01

    Fluoroquinolones and their metabolites are found in surface and ground waters, indicating their ineffective removal by conventional water treatment technologies. Advanced oxidation processes (AOPs) are alternatives to traditional water treatments. They utilize free radical reactions to directly degrade fluoroquinolones. This work reports absolute rate constants for the reaction of ciprofloxacin with several free radicals, OH, N3 and SO4? as well

  8. Determination of hydroxyl radicals in an advanced oxidation process with salicylic acid trapping and liquid chromatography

    Microsoft Academic Search

    Jen-Fon Jen; Meei-Fan Leu; Thomas C Yang

    1998-01-01

    Liquid chromatography was used indirectly to detect hydroxyl radicals after a trapping reaction with salicylic acid in an advanced oxidation process. Through the quantitative determination of primary hydroxylated derivatives of salicylic acid, the concentration of hydroxyl radicals was evaluated relatively. Factors affecting the trapping reaction, such as the ratio of salicylic acid to hydrogen peroxide and trapping time, as well

  9. Formation of nitroaromatic compounds in advanced oxidation processes: Photolysis versus photocatalysis

    Microsoft Academic Search

    Janet Dzengel; Joern Theurich; Detlef W. Bahnemann

    1999-01-01

    There is a growing demand for efficient treatment of organic polluted wastewaters by advanced oxidation processes (AOPs). Besides optimization of the processes, the detailed understanding of degradation mechanisms and interactions of organic pollutants with inorganic substrates is important for technical applications of AOPs. Therefore, the aim of the present study was to investigate the influence of nitrate ions on the

  10. Nutrient release from fish silage using microwave-enhanced advanced oxidation process

    Microsoft Academic Search

    Winnie I. Chan; K. Victor Lo; Ping H. Liao

    2009-01-01

    The microwave-enhanced advanced oxidation process was used to treat fish silage for nutrient release and solids reduction prior to its use as a fertilizer for greenhouse operations. Fifteen sets of experiments with varying hydrogen peroxide dosages and treatment temperatures were conducted to evaluate the effectiveness of the process on the solubilization of fertilizer constituents. It was found that up to

  11. Novel pilot plant-scale graywater treatment system using titanium ball, membrane and advanced oxidation process

    Microsoft Academic Search

    Joonkyu Kim; Insang Song; Sangjoon Lee; Pyoungsan Kim; Myounggeun Lee; Younkyoo Choung

    2009-01-01

    In this study, graywater, which is defined as all household wastewater originating from a source other than the toilet, was treated through a process combining titanium ball, microfiltration membrane and advanced oxidation treatment. Removal efficiency of COD, suspended solids, turbidity, color and E. coli was studied to determine the possibility of reuse of the graywater as water for fire fighting,

  12. A novel environmental risk-free microwave discharge electrodeless lamp (MDEL) in advanced oxidation processes

    Microsoft Academic Search

    Satoshi Horikoshi; Masatsugu Kajitani; Susumu Sato; Nick Serpone

    2007-01-01

    A novel microwave discharge electrodeless lamp (MDEL) has been developed for wastewater treatment with Advanced Oxidation Processes (AOPs) using environment risk-free gases (e.g., xenon, nitrogen, helium, oxygen, hydrogen and argon alone or a mixture thereof) that provide the needed light plasma source when microwave irradiated. The MDEL was optimized through an examination of the light intensity of the emitted radiation

  13. DESTRUCTION OF PAHS AND PCBS IN WATER USING SULFATE RADICAL-BASED CATALYTIC ADVANCED OXIDATION PROCESSES

    EPA Science Inventory

    A new class of advanced oxidation processes (AOPs) based on sulfate radicals is being tested for the degradation of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in aqueous solution. These AOPs are based on the generation of sulfate radicals through...

  14. Synthesis of bacteria promoted reduced graphene oxide-nickel sulfide networks for advanced supercapacitors.

    PubMed

    Zhang, Haiming; Yu, Xinzhi; Guo, Di; Qu, Baihua; Zhang, Ming; Li, Qiuhong; Wang, Taihong

    2013-08-14

    Supercapacitors with potential high power are useful and have attracted much attention recently. Graphene-based composites have been demonstrated to be promising electrode materials for supercapacitors with enhanced properties. To improve the performance of graphene-based composites further and realize their synthesis with large scale, we report a green approach to synthesize bacteria-reduced graphene oxide-nickel sulfide (BGNS) networks. By using Bacillus subtilis as spacers, we deposited reduced graphene oxide/Ni3S2 nanoparticle composites with submillimeter pores directly onto substrate by a binder-free electrostatic spray approach to form BGNS networks. Their electrochemical capacitor performance was evaluated. Compared with stacked reduced graphene oxide-nickel sulfide (GNS) prepared without the aid of bacteria, BGNS with unique nm-?m structure exhibited a higher specific capacitance of about 1424 F g(-1) at a current density of 0.75 A g(-1). About 67.5% of the capacitance was retained as the current density increased from 0.75 to 15 A g(-1). At a current density of 75 A g(-1), a specific capacitance of 406 F g(-1) could still remain. The results indicate that the reduced graphene oxide-nickel sulfide network promoted by bacteria is a promising electrode material for supercapacitors. PMID:23751359

  15. Degradation of diethyl phthalate in treated effluents from an MBR via advanced oxidation processes: Effects of nitrate on oxidation and a pilot?scale AOP operation

    Microsoft Academic Search

    J. H. Park; C. G. Park; J. W. Lee; K. B. Ko

    2010-01-01

    The major objective of this study was to delineate the oxidation of diethyl phthalate (DEP) in water, using bench?scale UV\\/H2O2 and O3\\/H2O2 processes, and to determine the effects of nitrate (NO3 ?N, 5 mg L) on this oxidation. The oxidation of DEP was also investigated through a pilot?scale advanced oxidation process (AOP), into which a portion of the effluent from

  16. Polyethylene Oxidation in Total Hip Arthroplasty: Evolution and New Advances

    PubMed Central

    Gómez-Barrena, Enrique; Medel, Francisco; Puértolas, José Antonio

    2009-01-01

    Ultra-high molecular weight polyethylene (UHMWPE) remains the gold standard acetabular bearing material for hip arthroplasty. Its successful performance has shown consistent results and survivorship in total hip replacement (THR) above 85% after 15 years, with different patients, surgeons, or designs. As THR results have been challenged by wear, oxidation, and liner fracture, relevant research on the material properties in the past decade has led to the development and clinical introduction of highly crosslinked polyethylenes (HXLPE). More stress on the bearing (more active, overweighted, younger patients), and more variability in the implantation technique in different small and large Hospitals may further compromise the clinical performance for many patients. The long-term in vivo performance of these materials remains to be proven. Clinical and retrieval studies after more than 5 years of in vivo use with HXLPE in THR are reviewed and consistently show a substantial decrease in wear rate. Moreover, a second generation of improved polyethylenes is backed by in vitro data and awaits more clinical experience to confirm the experimental improvements. Also, new antioxidant, free radical scavengers, candidates and the reinforcement of polyethylene through composites are currently under basic research. Oxidation of polyethylene is today significantly reduced by present formulations, and this forgiving, affordable, and wellknown material is still reliable to meet today’s higher requirements in total hip replacement. PMID:20111694

  17. Mechanism of Enhanced Electrochemical Oxidation of 2,4-dichlorophenoxyacetic Acid with in situ Microwave Activated Boron-doped Diamond and Platinum Anodes

    NASA Astrophysics Data System (ADS)

    Gao, Junxia; Zhao, Guohua; Liu, Meichuan; Li, Dongming

    2009-09-01

    Remarkable enhancement in degradation effect is achieved at in situ activated boron-doped diamond (BDD) and Pt anodes with different extent through electrochemical oxidation (EC) of 2,4-dichlorophenoxyacetic acid (2,4-D) with microwave (MW) radiation in a flow system. Results show that when EC is activated with MW radiation, the complete mineralization time of 2,4-D at the BDD is reduced quickly from 10 to 4 h while Chemical oxygen demand (COD) removal at Pt is increased from 37.7 to 58.3% at 10 h; the initial current efficiency is both improved about 1.5 times while the pseudo-first-order rate constant is increased by 153 and 119% at the BDD and Pt, respectively. To gain insight into the higher efficiency in microwave activated EC, the mechanism has therefore been systematically evaluated from the essence of electrochemical reaction and the accumulated hydroxyl radical concentration. 2,4-Dichlorophenol, catechol, benquinone, and maleic and oxalic acids are the main intermediates on the Pt anode measured by high performance liquid chromatography (HPLC), while the intermediates on the BDD electrode include 2,4-dichlorophenol, hydroquinone, and maleic and oxalic acids. The reaction pathway with microwave radiation is the same as that in a conventional electrochemical oxidation on both electrodes. While less and lower aromatic intermediates produce at the BDD with MW, which suggests the higher ring-open ratio and the faster oxidation of carboxylic acids. With microwave radiation, the ring-open ratio at the BDD is increased to 98.8% from 85.6%; the value at Pt is increased to 67.3% from 35.9%. So microwave radiation can activate the electrochemical oxidation, which leads to the higher efficiency. This promotion is mainly due to the higher accumulated hydroxyl radical concentration and the effects by microwave radiation. All the results prove that the BDD electrode presents much better mineralization performance with MW. To the best of our knowledge, it is the first time the systematic analysis of the mechanism of microwave activated EC has been reported.

  18. One-step solution combustion synthesis of cobalt-nickel oxides/C/Ni/CNTs nanocomposites as electrochemical capacitors electrode materials

    NASA Astrophysics Data System (ADS)

    Kang, Litao; Deng, Jiachun; Liu, Tiejun; Cui, Mangwei; Zhang, Xinyu; Li, Peiyang; Li, Ying; Liu, Xuguang; Liang, Wei

    2015-02-01

    With Co(NO3)2·6H2O (oxidizer and Co source), Ni(NO3)2·6H2O (oxidizer and Ni source) and citric acid (fuel) as starting materials, cobalt-nickel oxides/C/Ni ternary nanocomposites have been synthesized by a scalable, one-step solution combustion process at only 300 °C within 30 min in air. In these composites, the metallic nickel and amorphous carbon (conductive phases) were in situ formed by the reduction of Ni2+ and carbonization of the excess citric acid during combustion, respectively. Experimental results indicated that the fuel:oxidant and Co:Ni molar ratios in precursor solution showed strong influences on the phase composition, morphology and electrochemical performance of products. With the increase of the fuel dosage, the products transformed from well-crystallized cubic NiO/Ni to Ni (nickel-related phases), then to relatively amorphous Ni/NiO and finally NiO. Electrochemical tests indicated that the optimized product showed a high specific capacitance of 446 F g-1 at 1 A g-1 (or 280 F g-1 at 10 A g-1) with a Co:Ni:C6H8O7 molar ratio of 4:5:86/9. Significantly, besides its mild experimental conditions, the method could be used to prepare cobalt-nickel oxides/C/Ni/CNTs quarternary nanocomposites by simply adding acid-treated CNTs into precursor combustion solution. Thanks to the high electrical conduction of CNTs, the specific capacitance could be further improved up to 579 F g-1 at 1 A g-1, or 350 F g-1 at 10 A g-1.

  19. The use of the advanced oxidation process in the ozone + hydrogen peroxide system for the removal of cyanide from water

    Microsoft Academic Search

    Urszula Kepa; Ewa Stanczyk-Mazanek; Longina Stepniak

    2008-01-01

    The results of laboratory tests are presented in this paper, which demonstrate a possibility of using the advanced oxidation process for the removal of cyanide from the water. A comparative analysis was carried out for the processes of ozonation, oxidation with hydrogen peroxide and advanced oxidation in the O3 + H2O2 system.The paper presents experimental test results that indicate a

  20. Real-time, multiplexed electrochemical DNA detection using an active complementary metal-oxide-semiconductor biosensor array with integrated sensor electronics

    PubMed Central

    Levine, Peter M.; Gong, Ping; Levicky, Rastislav; Shepard, Kenneth L.

    2009-01-01

    Optical biosensing based on fluorescence detection has arguably become the standard technique for quantifying extents of hybridization between surface-immobilized probes and fluorophore-labeled analyte targets in DNA microarrays. However, electrochemical detection techniques are emerging which could eliminate the need for physically bulky optical instrumentation, enabling the design of portable devices for point-of-care applications. Unlike fluorescence detection, which can function well using a passive substrate (one without integrated electronics), multiplexed electrochemical detection requires an electronically-active substrate to analyze each array site and benefits from the addition of integrated electronic instrumentation to further reduce platform size and eliminate the electromagnetic interference that can result from bringing non-amplified signals off chip. We report on an active electrochemical biosensor array, constructed with a standard complementary metal-oxide-semiconductor (CMOS) technology, to perform quantitative DNA hybridization detection on chip using targets conjugated with ferrocene redox labels. A 4×4 array of gold working electrodes and integrated potentiostat electronics, consisting of control amplifiers and current-input analog-to-digital converters, on a custom-designed 5×3 mm2 CMOS chip drive redox reactions using cyclic voltammetry, sense DNA binding, and transmit digital data off chip for analysis. We demonstrate multiplexed and specific detection of DNA targets as well as real-time monitoring of hybridization, a task that is difficult, if not impossible, with traditional fluorescence-based microarrays. PMID:19054661