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Sample records for advanced electrochemical oxidation

  1. Electrochemical advanced oxidation processes: today and tomorrow. A review.

    Science.gov (United States)

    Sirés, Ignasi; Brillas, Enric; Oturan, Mehmet A; Rodrigo, Manuel A; Panizza, Marco

    2014-01-01

    In recent years, new advanced oxidation processes based on the electrochemical technology, the so-called electrochemical advanced oxidation processes (EAOPs), have been developed for the prevention and remediation of environmental pollution, especially focusing on water streams. These methods are based on the electrochemical generation of a very powerful oxidizing agent, such as the hydroxyl radical ((•)OH) in solution, which is then able to destroy organics up to their mineralization. EAOPs include heterogeneous processes like anodic oxidation and photoelectrocatalysis methods, in which (•)OH are generated at the anode surface either electrochemically or photochemically, and homogeneous processes like electro-Fenton, photoelectro-Fenton, and sonoelectrolysis, in which (•)OH are produced in the bulk solution. This paper presents a general overview of the application of EAOPs on the removal of aqueous organic pollutants, first reviewing the most recent works and then looking to the future. A global perspective on the fundamentals and experimental setups is offered, and laboratory-scale and pilot-scale experiments are examined and discussed.

  2. Implementation of advanced electrochemical oxidation for radiochemical concentrate treatment

    International Nuclear Information System (INIS)

    Velin, Anna; Bengtsson, Bernt; Lundblad, Magnus

    2012-09-01

    Water treatments in Nuclear Power Plants include ion exchange, evaporation and mechanical filtration techniques. These technologies are used to control the chemical release and to treat coolant in light water reactor types from chemicals and most importantly, from radioactive nuclides. Most of the conventional methods are efficient, but at the same time producing aqueous concentrates with high organic load. Before final storage, the level of organic content of those concentrates must be reduced. Advanced electrochemical oxidation with Boron Doped Diamond (BDD) electrodes are being investigated in laboratory- and pilot scale for treatment of dilute and concentrated aqueous waste streams at Vattenfall-Ringhals NPP. BDD anodes and cathodes are having high over potential against water electrolysis, and therefore well suitable for oxidation of organics. Dilute wastewater, such as laundry water, which has an initial COD level of around 500 mg/l, was reduced to a level of < 20 mg/l in the laboratory. Evaporator concentrates, with a TS content of 3% and pH of 7-8, were treated in pilot scale of 800 liters, working in batch operation mode, at temperatures between 25-50 deg. C. Initial COD levels between 2500 and 8000 mg/l in concentrate was reduced to < 100 mg/l at the first tests and later to < 300 mg/l. The advanced electrochemical oxidation is proven to be a promising technique for radioactive concentrate treatment. Long-term operation is still ongoing to evaluate the performance of the electrodes, cell components and overall process efficiency. (authors)

  3. Advanced impedance modeling of solid oxide electrochemical cells

    DEFF Research Database (Denmark)

    Graves, Christopher R.; Hjelm, Johan

    2014-01-01

    Impedance spectroscopy is a powerful technique for detailed study of the electrochemical and transport processes that take place in fuel cells and electrolysis cells, including solid oxide cells (SOCs). Meaningful analysis of impedance measurements is nontrivial, however, because a large number...... techniques to provide good guesses for the modeling parameters, like transforming the impedance data to the distribution of relaxation times (DRT), together with experimental parameter sensitivity studies, is the state-of-the-art approach to achieve good EC model fits. Here we present new impedance modeling...... electrode and 2-D gas transport models which have fewer unknown parameters for the same number of processes, (ii) use of a new model fitting algorithm, “multi-fitting”, in which multiple impedance spectra are fit simultaneously with parameters linked based on the variation of measurement conditions, (iii...

  4. Alkaline electrochemical advanced oxidation process for chromium oxidation at graphitized multi-walled carbon nanotubes.

    Science.gov (United States)

    Xue, Yudong; Zheng, Shili; Sun, Zhi; Zhang, Yi; Jin, Wei

    2017-09-01

    Alkaline electrochemical advanced oxidation processes for chromium oxidation and Cr-contaminated waste disposal were reported in this study. The highly graphitized multi-walled carbon nanotubes g-MWCNTs modified electrode was prepared for the in-situ electrochemical generation of HO 2 - . RRDE test results illustrated that g-MWCNTs exhibited much higher two-electron oxygen reduction activity than other nanocarbon materials with peak current density of 1.24 mA cm -2 , %HO 2 - of 77.0% and onset potential of -0.15 V (vs. Hg/HgO). It was originated from the highly graphitized structure and good electrical conductivity as illustrated from the Raman, XRD and EIS characterizations, respectively. Large amount of reactive oxygen species (HO 2 - and ·OH) were in-situ electro-generated from the two-electron oxygen reduction and chromium-induced alkaline electro-Fenton-like reaction. The oxidation of Cr(III) was efficiently achieved within 90 min and the conversion ratio maintained more than 95% of the original value after stability test, offering an efficient and green approach for the utilization of Cr-containing wastes. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. An overview on the removal of synthetic dyes from water by electrochemical advanced oxidation processes.

    Science.gov (United States)

    Nidheesh, P V; Zhou, Minghua; Oturan, Mehmet A

    2018-04-01

    Wastewater containing dyes are one of the major threats to our environment. Conventional methods are insufficient for the removal of these persistent organic pollutants. Recently much attention has been received for the oxidative removal of various organic pollutants by electrochemically generated hydroxyl radical. This review article aims to provide the recent trends in the field of various Electrochemical Advanced Oxidation Processes (EAOPs) used for removing dyes from water medium. The characteristics, fundamentals and recent advances in each processes namely anodic oxidation, electro-Fenton, peroxicoagulation, fered Fenton, anodic Fenton, photoelectro-Fenton, sonoelectro-Fenton, bioelectro-Fenton etc. have been examined in detail. These processes have great potential to destroy persistent organic pollutants in aqueous medium and most of the studies reported complete removal of dyes from water. The great capacity of these processes indicates that EAOPs constitute a promising technology for the treatment of the dye contaminated effluents. Copyright © 2018 Elsevier Ltd. All rights reserved.

  6. Remediation of a winery wastewater combining aerobic biological oxidation and electrochemical advanced oxidation processes.

    Science.gov (United States)

    Moreira, Francisca C; Boaventura, Rui A R; Brillas, Enric; Vilar, Vítor J P

    2015-05-15

    Apart from a high biodegradable fraction consisting of organic acids, sugars and alcohols, winery wastewaters exhibit a recalcitrant fraction containing high-molecular-weight compounds as polyphenols, tannins and lignins. In this context, a winery wastewater was firstly subjected to a biological oxidation to mineralize the biodegradable fraction and afterwards an electrochemical advanced oxidation process (EAOP) was applied in order to mineralize the refractory molecules or transform them into simpler ones that can be further biodegraded. The biological oxidation led to above 97% removals of dissolved organic carbon (DOC), chemical oxygen demand (COD) and 5-day biochemical oxygen demand (BOD5), but was inefficient on the degradation of a bioresistant fraction corresponding to 130 mg L(-1) of DOC, 380 mg O2 L(-1) of COD and 8.2 mg caffeic acid equivalent L(-1) of total dissolved polyphenols. Various EAOPs such as anodic oxidation with electrogenerated H2O2 (AO-H2O2), electro-Fenton (EF), UVA photoelectro-Fenton (PEF) and solar PEF (SPEF) were then applied to the recalcitrant effluent fraction using a 2.2 L lab-scale flow plant containing an electrochemical cell equipped with a boron-doped diamond (BDD) anode and a carbon-PTFE air-diffusion cathode and coupled to a photoreactor with compound parabolic collectors (CPCs). The influence of initial Fe(2+) concentration and current density on the PEF process was evaluated. The relative oxidative ability of EAOPs increased in the order AO-H2O2 < EF < PEF ≤ SPEF. The SPEF process using an initial Fe(2+) concentration of 35 mg L(-1), current density of 25 mA cm(-2), pH of 2.8 and 25 °C reached removals of 86% on DOC and 68% on COD after 240 min, regarding the biologically treated effluent, along with energy consumptions of 45 kWh (kg DOC)(-1) and 5.1 kWh m(-3). After this coupled treatment, color, odor, COD, BOD5, NH4(+), NO3(-) and SO4(2-) parameters complied with the legislation targets and, in addition, a total

  7. Electrochemical advanced oxidation processes as decentralized water treatment technologies to remediate domestic washing machine effluents.

    Science.gov (United States)

    Dos Santos, Alexsandro Jhones; Costa, Emily Cintia Tossi de Araújo; da Silva, Djalma Ribeiro; Garcia-Segura, Sergi; Martínez-Huitle, Carlos Alberto

    2018-03-01

    Water scarcity is one of the major concerns worldwide. In order to secure this appreciated natural resource, management and development of water treatment technologies are mandatory. One feasible alternative is the consideration of water recycling/reuse at the household scale. Here, the treatment of actual washing machine effluent by electrochemical advanced oxidation processes was considered. Electrochemical oxidation and electro-Fenton technologies can be applied as decentralized small-scale water treatment devices. Therefore, efficient decolorization and total organic abatement have been followed. The results demonstrate the promising performance of solar photoelectro-Fenton process, where complete color and organic removal was attained after 240 min of treatment under optimum conditions by applying a current density of 66.6 mA cm -2 . Thus, electrochemical technologies emerge as promising water-sustainable approaches.

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

    Science.gov (United States)

    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.

  9. Fabrication of Electrochemically Reduced Graphene Oxide Modified Gas Diffusion Electrode for In-situ Electrochemical Advanced Oxidation Process under Mild Conditions

    International Nuclear Information System (INIS)

    Dong, Heng; Su, Huimin; Chen, Ze; Yu, Han; Yu, Hongbing

    2016-01-01

    With aim to develop an efficient heterogeneous metal-free cathodic electrochemical advance oxidation process (CEAOP) for persistent organic pollutants (POPs) removal from wastewater under mild conditions, electrochemically reduced graphene oxide (ERGO)-modified gas diffusion electrode (GDE) was prepared for oxygen-containing radicals production via electrochemical oxygen reduction reaction (ORR). A detailed physical characterization was carried out by SEM, Raman spectroscopy, XRD and XPS. The electrocatalytic behavior for ORR was investigated by electrochemical measurements and electrolysis experiments under constant current density. Bisphenol A (BPA) of 20 mg L −1 was used as a model of POPs to evaluate the performance of the CEAOP with ERGO-modified GDE. The results showed that the defects concentration and electrochemical active sites of the ERGO was increased as the reduction time (30 min, 60 min and 120 min), leading to different catalysis on ORR. ·O 2 generation via one-electron ORR was found under the electrocatalysis of ERGO (60 min and 120 min), contributing to a complete degradation of BPA within 20 min and a mineralization current efficiency (MCE) of 74.60%. An alternative metal-free CEAOP independent of Fenton reaction was established based on ERGO-modified GDE for POPs removal from wastewater under mild conditions.

  10. Treatment of winery wastewater by electrochemical methods and advanced oxidation processes.

    Science.gov (United States)

    Orescanin, Visnja; Kollar, Robert; Nad, Karlo; Mikelic, Ivanka Lovrencic; Gustek, Stefica Findri

    2013-01-01

    The aim of this research was development of new system for the treatment of highly polluted wastewater (COD = 10240 mg/L; SS = 2860 mg/L) originating from vine-making industry. The system consisted of the main treatment that included electrochemical methods (electro oxidation, electrocoagulation using stainless steel, iron and aluminum electrode sets) with simultaneous sonication and recirculation in strong electromagnetic field. Ozonation combined with UV irradiation in the presence of added hydrogen peroxide was applied for the post-treatment of the effluent. Following the combined treatment, the final removal efficiencies of the parameters color, turbidity, suspended solids and phosphates were over 99%, Fe, Cu and ammonia approximately 98%, while the removal of COD and sulfates was 77% and 62%, respectively. A new approach combining electrochemical methods with ultrasound in the strong electromagnetic field resulted in significantly better removal efficiencies for majority of the measured parameters compared to the biological methods, advanced oxidation processes or electrocoagulation. Reduction of the treatment time represents another advantage of this new approach.

  11. Recent advances in metal oxide-based electrode architecture design for electrochemical energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Jian; Liu, Jinping; Huang, Xintang [Institute of Nanoscience and Nanotechnology, Department of Physics, Central China Normal University, Wuhan, Hubei (China); Li, Yuanyuan [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan (China); Yuan, Changzhou; Lou, Xiong Wen [School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore (China)

    2012-10-02

    Metal oxide nanostructures are promising electrode materials for lithium-ion batteries and supercapacitors because of their high specific capacity/capacitance, typically 2-3 times higher than that of the carbon/graphite-based materials. However, their cycling stability and rate performance still can not meet the requirements of practical applications. It is therefore urgent to improve their overall device performance, which depends on not only the development of advanced electrode materials but also in a large part ''how to design superior electrode architectures''. In the article, we will review recent advances in strategies for advanced metal oxide-based hybrid nanostructure design, with the focus on the binder-free film/array electrodes. These binder-free electrodes, with the integration of unique merits of each component, can provide larger electrochemically active surface area, faster electron transport and superior ion diffusion, thus leading to substantially improved cycling and rate performance. Several recently emerged concepts of using ordered nanostructure arrays, synergetic core-shell structures, nanostructured current collectors, and flexible paper/textile electrodes will be highlighted, pointing out advantages and challenges where appropriate. Some future electrode design trends and directions are also discussed. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Recent advances in metal oxide-based electrode architecture design for electrochemical energy storage.

    Science.gov (United States)

    Jiang, Jian; Li, Yuanyuan; Liu, Jinping; Huang, Xintang; Yuan, Changzhou; Lou, Xiong Wen David

    2012-10-02

    Metal oxide nanostructures are promising electrode materials for lithium-ion batteries and supercapacitors because of their high specific capacity/capacitance, typically 2-3 times higher than that of the carbon/graphite-based materials. However, their cycling stability and rate performance still can not meet the requirements of practical applications. It is therefore urgent to improve their overall device performance, which depends on not only the development of advanced electrode materials but also in a large part "how to design superior electrode architectures". In the article, we will review recent advances in strategies for advanced metal oxide-based hybrid nanostructure design, with the focus on the binder-free film/array electrodes. These binder-free electrodes, with the integration of unique merits of each component, can provide larger electrochemically active surface area, faster electron transport and superior ion diffusion, thus leading to substantially improved cycling and rate performance. Several recently emerged concepts of using ordered nanostructure arrays, synergetic core-shell structures, nanostructured current collectors, and flexible paper/textile electrodes will be highlighted, pointing out advantages and challenges where appropriate. Some future electrode design trends and directions are also discussed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Toxicological and chemical assessment of arsenic-contaminated groundwater after electrochemical and advanced oxidation treatments.

    Science.gov (United States)

    Radić, Sandra; Crnojević, Helena; Vujčić, Valerija; Gajski, Goran; Gerić, Marko; Cvetković, Želimira; Petra, Cvjetko; Garaj-Vrhovac, Vera; Oreščanin, Višnja

    2016-02-01

    Owing to its proven toxicity and mutagenicity, arsenic is regarded a principal pollutant in water used for drinking. The objective of this study was the toxicological and chemical evaluation of groundwater samples obtained from arsenic enriched drinking water wells before and after electrochemical and ozone-UV-H2O2-based advanced oxidation processes (EAOP). For this purpose, acute toxicity test with Daphnia magna and chronic toxicity test with Lemna minor L. were employed as well as in vitro bioassays using human peripheral blood lymphocytes (HPBLs). Several oxidative stress parameters were estimated in L.minor. Physicochemical analysis showed that EAOP treatment was highly efficient in arsenic but also in ammonia and organic compound removal from contaminated groundwater. Untreated groundwater caused only slight toxicity to HPBLs and D. magna in acute experiments. However, 7-day exposure of L. minor to raw groundwater elicited genotoxicity, a significant growth inhibition and oxidative stress injury. The observed genotoxicity and toxicity of raw groundwater samples was almost completely eliminated by EAOP treatment. Generally, the results obtained with L. minor were in agreement with those obtained in the chemical analysis suggesting the sensitivity of the model organism in monitoring of arsenic-contaminated groundwater. In parallel to chemical analysis, the implementation of chronic toxicity bioassays in a battery is recommended in the assessment of the toxic and genotoxic potential of such complex mixtures. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Parabens abatement from surface waters by electrochemical advanced oxidation with boron doped diamond anodes.

    Science.gov (United States)

    Domínguez, Joaquín R; Muñoz-Peña, Maria J; González, Teresa; Palo, Patricia; Cuerda-Correa, Eduardo M

    2016-10-01

    The removal efficiency of four commonly-used parabens by electrochemical advanced oxidation with boron-doped diamond anodes in two different aqueous matrices, namely ultrapure water and surface water from the Guadiana River, has been analyzed. Response surface methodology and a factorial, composite, central, orthogonal, and rotatable (FCCOR) statistical design of experiments have been used to optimize the process. The experimental results clearly show that the initial concentration of pollutants is the factor that influences the removal efficiency in a more remarkable manner in both aqueous matrices. As a rule, as the initial concentration of parabens increases, the removal efficiency decreases. The current density also affects the removal efficiency in a statistically significant manner in both aqueous matrices. In the water river aqueous matrix, a noticeable synergistic effect on the removal efficiency has been observed, probably due to the presence of chloride ions that increase the conductivity of the solution and contribute to the generation of strong secondary oxidant species such as chlorine or HClO/ClO - . The use of a statistical design of experiments made it possible to determine the optimal conditions necessary to achieve total removal of the four parabens in ultrapure and river water aqueous matrices.

  15. Degradation of the fluoroquinolone enrofloxacin by electrochemical advanced oxidation processes based on hydrogen peroxide electrogeneration

    Energy Technology Data Exchange (ETDEWEB)

    Guinea, Elena; Garrido, Jose Antonio; Rodriguez, Rosa Maria; Cabot, Pere-Lluis; Arias, Conchita; Centellas, Francesc [Laboratori d' Electroquimica dels Materials i del Medi Ambient, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Brillas, Enric, E-mail: brillas@ub.ed [Laboratori d' Electroquimica dels Materials i del Medi Ambient, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain)

    2010-02-15

    Solutions of the veterinary fluoroquinolone antibiotic enrofloxacin in 0.05 M Na{sub 2}SO{sub 4} of pH 3.0 have been comparatively degraded by electrochemical advanced oxidation processes such as anodic oxidation with electrogenerated H{sub 2}O{sub 2} (AO-H{sub 2}O{sub 2}), electro-Fenton (EF), photoelectro-Fenton (PEF) and solar photoelectro-Fenton (SPEF) at constant current density. The study has been performed using an undivided stirred tank reactor of 100 ml and a batch recirculation flow plant of 2.5 l with an undivided filter-press cell coupled to a solar photoreactor, both equipped with a Pt or boron-doped diamond (BDD) anode and a carbon-polytetrafluoroethylene gas diffusion cathode to generate H{sub 2}O{sub 2} from O{sub 2} reduction. In EF, PEF and SPEF, hydroxyl radical (centre dotOH) is formed from Fenton's reaction between added catalytic Fe{sup 2+} and generated H{sub 2}O{sub 2}. Almost total decontamination of enrofloxacin solutions is achieved in the stirred tank reactor by SPEF with BDD. The use of the batch recirculation flow plant showed that this process is the most efficient and can be viable for industrial application, becoming more economic and yielding higher mineralization degree with raising antibiotic content. This is feasible because organics are quickly oxidized with centre dotOH formed from Fenton's reaction and at BDD from water oxidation, combined with the fast photolysis of complexes of Fe(III) with generated carboxylic acids under solar irradiation. The lower intensity of UVA irradiation used in PEF with BDD causes a slower degradation. EF with BDD is less efficient since centre dotOH cannot destroy the most persistent Fe(III)-oxalate and Fe(III)-oxamate complexes. AO-H{sub 2}O{sub 2} with BDD yields the poorest mineralization because pollutants are only removed with centre dotOH generated at BDD. All procedures are less potent using Pt as anode due to the lower production of centre dotOH at its surface. Enrofloxacin

  16. Degradation of the fluoroquinolone enrofloxacin by electrochemical advanced oxidation processes based on hydrogen peroxide electrogeneration

    International Nuclear Information System (INIS)

    Guinea, Elena; Garrido, Jose Antonio; Rodriguez, Rosa Maria; Cabot, Pere-Lluis; Arias, Conchita; Centellas, Francesc; Brillas, Enric

    2010-01-01

    Solutions of the veterinary fluoroquinolone antibiotic enrofloxacin in 0.05 M Na 2 SO 4 of pH 3.0 have been comparatively degraded by electrochemical advanced oxidation processes such as anodic oxidation with electrogenerated H 2 O 2 (AO-H 2 O 2 ), electro-Fenton (EF), photoelectro-Fenton (PEF) and solar photoelectro-Fenton (SPEF) at constant current density. The study has been performed using an undivided stirred tank reactor of 100 ml and a batch recirculation flow plant of 2.5 l with an undivided filter-press cell coupled to a solar photoreactor, both equipped with a Pt or boron-doped diamond (BDD) anode and a carbon-polytetrafluoroethylene gas diffusion cathode to generate H 2 O 2 from O 2 reduction. In EF, PEF and SPEF, hydroxyl radical (·OH) is formed from Fenton's reaction between added catalytic Fe 2+ and generated H 2 O 2 . Almost total decontamination of enrofloxacin solutions is achieved in the stirred tank reactor by SPEF with BDD. The use of the batch recirculation flow plant showed that this process is the most efficient and can be viable for industrial application, becoming more economic and yielding higher mineralization degree with raising antibiotic content. This is feasible because organics are quickly oxidized with ·OH formed from Fenton's reaction and at BDD from water oxidation, combined with the fast photolysis of complexes of Fe(III) with generated carboxylic acids under solar irradiation. The lower intensity of UVA irradiation used in PEF with BDD causes a slower degradation. EF with BDD is less efficient since ·OH cannot destroy the most persistent Fe(III)-oxalate and Fe(III)-oxamate complexes. AO-H 2 O 2 with BDD yields the poorest mineralization because pollutants are only removed with ·OH generated at BDD. All procedures are less potent using Pt as anode due to the lower production of ·OH at its surface. Enrofloxacin decay always follows a pseudo first-order reaction. Its primary aromatic by-products and short intermediates

  17. Decolorization and mineralization of Allura Red AC aqueous solutions by electrochemical advanced oxidation processes

    Energy Technology Data Exchange (ETDEWEB)

    Thiam, Abdoulaye; Sirés, Ignasi; Garrido, José A.; Rodríguez, Rosa M.; Brillas, Enric, E-mail: brillas@ub.edu

    2015-06-15

    Highlights: • Quicker degradation of Allura Red AC in the order EO-H{sub 2}O{sub 2} < EF < PEF with Pt or BDD anode. • Almost total mineralization achieved by the most powerful PEF process with BDD. • Similar decolorization and mineralization rate in SO{sub 4}{sup 2−}, ClO{sub 4}{sup −} and NO{sub 3}{sup −} media. • In Cl{sup −} medium, only slightly larger decolorization rate but strong inhibition of mineralization. • Identification of aromatic products, carboxylic acids and released NH{sub 4}{sup +}, NO{sub 3}{sup −} and SO{sub 4}{sup 2−} ions. - Abstract: The decolorization and mineralization of solutions containing 230 mg L{sup −1} of the food azo dye Allura Red AC at pH 3.0 have been studied upon treatment by electrochemical oxidation with electrogenerated H{sub 2}O{sub 2} (EO-H{sub 2}O{sub 2}), electro-Fenton (EF) and photoelectro-Fenton (PEF). Experiments were performed with a stirred tank reactor containing a boron-doped diamond (BDD) or Pt anode and an air-diffusion cathode to generate H{sub 2}O{sub 2}. The main oxidants were hydroxyl radicals formed at the anode surface from water oxidation and in the bulk from Fenton’s reaction between H{sub 2}O{sub 2} and added Fe{sup 2+}. The oxidation ability increased in the sequence EO-H{sub 2}O{sub 2} < EF < PEF and faster degradation was always obtained using BDD. PEF process with BDD yielded almost total mineralization following similar trends in SO{sub 4}{sup 2−}, ClO{sub 4}{sup −} and NO{sub 3}{sup −} media, whereas in Cl{sup −} medium, mineralization was inhibited by the formation of recalcitrant chloroderivatives. GC–MS analysis confirmed the cleavage of the −N=N− bond with formation of two main aromatics in SO{sub 4}{sup 2−} medium and three chloroaromatics in Cl{sup −} solutions. The effective oxidation of final oxalic and oxamic acids by BDD along with the photolysis of Fe(III)-oxalate species by UVA light accounted for the superiority of PEF with BDD. NH{sub 4

  18. Decolorization and mineralization of Allura Red AC aqueous solutions by electrochemical advanced oxidation processes

    International Nuclear Information System (INIS)

    Thiam, Abdoulaye; Sirés, Ignasi; Garrido, José A.; Rodríguez, Rosa M.; Brillas, Enric

    2015-01-01

    Highlights: • Quicker degradation of Allura Red AC in the order EO-H 2 O 2 < EF < PEF with Pt or BDD anode. • Almost total mineralization achieved by the most powerful PEF process with BDD. • Similar decolorization and mineralization rate in SO 4 2− , ClO 4 − and NO 3 − media. • In Cl − medium, only slightly larger decolorization rate but strong inhibition of mineralization. • Identification of aromatic products, carboxylic acids and released NH 4 + , NO 3 − and SO 4 2− ions. - Abstract: The decolorization and mineralization of solutions containing 230 mg L −1 of the food azo dye Allura Red AC at pH 3.0 have been studied upon treatment by electrochemical oxidation with electrogenerated H 2 O 2 (EO-H 2 O 2 ), electro-Fenton (EF) and photoelectro-Fenton (PEF). Experiments were performed with a stirred tank reactor containing a boron-doped diamond (BDD) or Pt anode and an air-diffusion cathode to generate H 2 O 2 . The main oxidants were hydroxyl radicals formed at the anode surface from water oxidation and in the bulk from Fenton’s reaction between H 2 O 2 and added Fe 2+ . The oxidation ability increased in the sequence EO-H 2 O 2 < EF < PEF and faster degradation was always obtained using BDD. PEF process with BDD yielded almost total mineralization following similar trends in SO 4 2− , ClO 4 − and NO 3 − media, whereas in Cl − medium, mineralization was inhibited by the formation of recalcitrant chloroderivatives. GC–MS analysis confirmed the cleavage of the −N=N− bond with formation of two main aromatics in SO 4 2− medium and three chloroaromatics in Cl − solutions. The effective oxidation of final oxalic and oxamic acids by BDD along with the photolysis of Fe(III)-oxalate species by UVA light accounted for the superiority of PEF with BDD. NH 4 + , NO 3 − and SO 4 2− ions were released during the mineralization

  19. Solid oxide electrochemical reactor science.

    Energy Technology Data Exchange (ETDEWEB)

    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.

  20. Test Concept for Advanced Oxidation Techniques

    DEFF Research Database (Denmark)

    Bennedsen, Lars Rønn; Søgaard, Erik Gydesen; Mortensen, Lars

    advanced on-site oxidation tests. The remediation techniques included are electrochemical oxidation, photochemical/photocatalytic oxidation, ozone, hydrogen peroxide, permanganate, and persulfate among others. A versatile construction of the mobile test unit makes it possible to combine different...

  1. Removal of arsenic, phosphates and ammonia from well water using electrochemical/chemical methods and advanced oxidation: a pilot plant approach.

    Science.gov (United States)

    Orescanin, Visnja; Kollar, Robert; Nad, Karlo; Halkijevic, Ivan; Kuspilic, Marin; Findri Gustek, Stefica

    2014-01-01

    The purpose of this work was to develop a pilot plant purification system and apply it to groundwater used for human consumption, containing high concentrations of arsenic and increased levels of phosphates, ammonia, mercury and color. The groundwater used was obtained from the production well in the Vinkovci County (Eastern Croatia). Due to a complex composition of the treated water, the purification system involved a combined electrochemical treatment, using iron and aluminum electrode plates with simultaneous ozonation, followed by a post-treatment with UV, ozone and hydrogen peroxide. The removal of the contaminant with the waste sludge collected during the electrochemical treatment was also tested. The combined electrochemical and advanced oxidation treatment resulted in the complete removal of arsenic, phosphates, color, turbidity, suspended solids and ammonia, while the removal of other contaminants of interest was up to 96.7%. Comparable removal efficiencies were obtained by using waste sludge as a coagulant.

  2. Electrochemical disinfection of groundwater for civil use - An example of an effective endogenous advanced oxidation process.

    Science.gov (United States)

    De Battisti, Achille; Formaglio, Paolo; Ferro, Sergio; Al Aukidy, Mustafa; Verlicchi, Paola

    2018-09-01

    Lab-scale experiments using real groundwater were carried out using the CabECO ® reactor system in order to evaluate its suitability for producing safe water, acceptable for civil purposes. Trials were carried out in discontinuous and in continuous mode, analyzing the influence of electrical and hydraulic process parameters on the quality of treated water. The use of highly boron-doped diamond electrodes in the reactor allowed the electrosynthesis of considerable amounts of ozone. Because of the relatively high amount of chloride in the groundwater samples, a mixture of HOCl/ClO - was also synthesized. Somewhat unexpectedly, the increase in the current density in the explored range 100-1000 A m -2 was accompanied by an increase in the faradaic yield of the electrosynthesis of oxidants, which was more pronounced for ozone than for free chlorine. As reported in literature, the main radical intermediate in the relevant reactions is OH, which can lead to different oxidation products, namely ozone and HOCl/ClO - . The electrolytic treatment also caused a decrease in the concentration of minor components, including NH 4 + and Br - . Other byproducts were ClO 3 - and ClO 4 - , although their concentration levels were low. Moreover, due to alkali formation at the cathode surface, the precipitation of calcium and magnesium carbonates was also observed. In addition, the experimental investigation showed that even Pseudomonas aeruginosa and Legionella could be completely removed in the treated stream, due to the unique capacity of the reactor to synthesize biocidal agents like ozone, HOCl/ClO - , and chloramines. These effects were particularly evident during batch experiments. Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.

  3. Performance of a Steel/Oxide Composite Waste Form for Combined Waste Steams from Advanced Electrochemical Processes

    International Nuclear Information System (INIS)

    Indacochea, J. E.; Gattu, V. K.; Chen, X.; Rahman, T.

    2017-01-01

    The results of electrochemical corrosion tests and modeling activities performed collaboratively by researchers at the University of Illinois at Chicago and Argonne National Laboratory as part of workpackage NU-13-IL-UIC-0203-02 are summarized herein. The overall objective of the project was to develop and demonstrate testing and modeling approaches that could be used to evaluate the use of composite alloy/ceramic materials as high-level durable waste forms. Several prototypical composite waste form materials were made from stainless steels representing fuel cladding, reagent metals representing metallic fuel waste streams, and reagent oxides representing oxide fuel waste streams to study the microstructures and corrosion behaviors of the oxide and alloy phases. Microelectrodes fabricated from small specimens of the composite materials were used in a series of electrochemical tests to assess the corrosion behaviors of the constituent phases and phase boundaries in an aggressive acid brine solution at various imposed surface potentials. The microstructures were characterized in detail before and after the electrochemical tests to relate the electrochemical responses to changes in both the electrode surface and the solution composition. The results of microscopic, electrochemical, and solution analyses were used to develop equivalent circuit and physical models representing the measured corrosion behaviors of the different materials pertinent to long-term corrosion behavior. This report provides details regarding (1) the production of the composite materials, (2) the protocol for the electrochemical measurements and interpretations of the responses of multi-phase alloy and oxide composites, (3) relating corrosion behaviors to microstructures of multi-phase alloys based on 316L stainless steel and HT9 (410 stainless steel was used as a substitute) with added Mo, Ni, and/or Mn, and (4) modeling the corrosion behaviors and rates of several alloy/oxide composite

  4. Performance of a Steel/Oxide Composite Waste Form for Combined Waste Steams from Advanced Electrochemical Processes

    Energy Technology Data Exchange (ETDEWEB)

    Indacochea, J. E. [Univ. of Illinois, Chicago, IL (United States); Gattu, V. K. [Univ. of Illinois, Chicago, IL (United States); Chen, X. [Univ. of Illinois, Chicago, IL (United States); Rahman, T. [Univ. of Illinois, Chicago, IL (United States)

    2017-06-15

    The results of electrochemical corrosion tests and modeling activities performed collaboratively by researchers at the University of Illinois at Chicago and Argonne National Laboratory as part of workpackage NU-13-IL-UIC-0203-02 are summarized herein. The overall objective of the project was to develop and demonstrate testing and modeling approaches that could be used to evaluate the use of composite alloy/ceramic materials as high-level durable waste forms. Several prototypical composite waste form materials were made from stainless steels representing fuel cladding, reagent metals representing metallic fuel waste streams, and reagent oxides representing oxide fuel waste streams to study the microstructures and corrosion behaviors of the oxide and alloy phases. Microelectrodes fabricated from small specimens of the composite materials were used in a series of electrochemical tests to assess the corrosion behaviors of the constituent phases and phase boundaries in an aggressive acid brine solution at various imposed surface potentials. The microstructures were characterized in detail before and after the electrochemical tests to relate the electrochemical responses to changes in both the electrode surface and the solution composition. The results of microscopic, electrochemical, and solution analyses were used to develop equivalent circuit and physical models representing the measured corrosion behaviors of the different materials pertinent to long-term corrosion behavior. This report provides details regarding (1) the production of the composite materials, (2) the protocol for the electrochemical measurements and interpretations of the responses of multi-phase alloy and oxide composites, (3) relating corrosion behaviors to microstructures of multi-phase alloys based on 316L stainless steel and HT9 (410 stainless steel was used as a substitute) with added Mo, Ni, and/or Mn, and (4) modeling the corrosion behaviors and rates of several alloy/oxide composite

  5. Synthesis of multilayered structure of nano-dimensional silica glass/reduced graphene oxide for advanced electrochemical applications.

    Science.gov (United States)

    Ghosh, Arnab; Miah, Milon; Majumder, Chinmoy; Bag, Shekhar; Chakravorty, Dipankar; Saha, Shyamal Kumar

    2018-03-28

    During the past few years, intensive research has been carried out to design new functional materials for superior electrochemical applications. Due to low storage capacity and low charge transport, silica based glasses have not yet been investigated for their supercapacitive behavior. Therefore, in the present study, a multilayered structure of silica-based nanoglass and reduced graphene oxide has been designed to remarkably enhance the specific capacitance by exploiting the porosity, large surface area, sufficient dangling bonds in the nanoglass and high electrical conductivity of rGO. The charge transport in the composite structure is also investigated to understand the electrochemical properties. It is found that Simmons tunneling or direct tunneling is the dominant mechanism of charge conduction between the graphene layers via the potential barrier of silica nanoglass phase. We believe that this study will open up a new area in the design of glass-based two-dimensional nanocomposites for superior supercapacitor applications.

  6. Electrochemical oxidation of organic waste

    International Nuclear Information System (INIS)

    Almon, A.C.; Buchanan, B.R.

    1990-01-01

    Both silver catalyzed and direct electrochemical oxidation of organic species are examined in analytical detail. This paper describes the mechanisms, reaction rates, products, intermediates, capabilities, limitations, and optimal reaction conditions of the electrochemical destruction of organic waste. A small bench-top electrocell being tested for the treatment of small quantities of laboratory waste is described. The 200-mL electrochemical cell used has a processing capacity of 50 mL per day, and can treat both radioactive and nonradioactive waste. In the silver catalyzed process, Ag(I) is electrochemically oxidized to Ag(II), which attacks organic species such as tributylphosphate (TBP), tetraphenylborate (TPB), and benzene. In direct electrochemical oxidation, the organic species are destroyed at the surface of the working electrode without the use of silver as an electron transfer agent. This paper focuses on the destruction of tributylphosphate (TBP), although several organic species have been destroyed using this process. The organic species are converted to carbon dioxide, water, and inorganic acids

  7. Recent Advances in Electrochemical Glycobiosensing

    Directory of Open Access Journals (Sweden)

    Germarie Sánchez-Pomales

    2011-01-01

    Full Text Available Biosensors based on electrochemical transduction mechanisms have recently made advances into the field of glycan analysis. These glyco-biosensors offer simple, rapid, sensitive, and economical approaches to the measurement need for rapid glycan analysis for biomarker detection, cancer and disease diagnostics, and bioprocess monitoring of therapeutic glycoproteins. Although the prevalent methods of glycan analysis (high-performance liquid chromatography, mass spectrometry, and nuclear magnetic resonance spectroscopy provide detailed identification and structural analysis of glycan species, there are significantly few low-cost, rapid glycan assays available for diagnostic and screening applications. Here we review instances in which glyco-biosensors have been used for glycan analysis using a variety of electrochemical transduction mechanisms (e.g., amperometric, potentiometric, impedimetric, and voltammetric, selective binding agents (e.g., lectins and antibodies, and redox species (e.g., enzyme substrates, inorganic, and nanomaterial.

  8. Electrochemically active biofilm and photoelectrocatalytic regeneration of the titanium dioxide composite electrode for advanced oxidation in water treatment

    International Nuclear Information System (INIS)

    Bennani, Yasmina; Peters, Marjolein C.F.M.; Appel, Peter W.; Rietveld, Luuk C.

    2015-01-01

    A novel bio-photoelectrocatalytic system was used to effectively reduce phenol as a model organic pollutant through the utilization of energy derived from bacteria and the use of solar energy for activation of TiO 2 . In such a system, a synergistic effect occurs between the bio-electrochemical and photocatalytic oxidation processes. TiO 2 /Ti composite electrodes were operated with variable biofilm coverage (partially developed biofilm after 6 days and fully developed biofilms after 12, 20 and 40 days at room temperature and pH 7). The study depicted the effectiveness of biofilm formation in enhancing the electron transfer. Kinetic analysis showed that the system exhibited a more rapid phenol degradation at a rate two times higher than rates by individual photo(electro) catalytic and biodegradable methods. Higher current density (8.4 × 10 −2 mAcm −2 ) and phenol removal efficiency of 62% after four hours of irradiation were observed especially with electrochemically active biofilm developed after 20 days. TiO 2 /Ti composite electrode. After the additional application of cleaning process, the TiO 2 /Ti composite electrode could be used several times with nearly the same efficiency, leading to decrease in the final cost of the treatment process.

  9. Electrochemical, Chemical and Enzymatic Oxidations of Phenothiazines

    NARCIS (Netherlands)

    Blankert, B.; Hayen, H.; van Leeuwen, S.M.; Karst, U.; Bodoki, E.; Lotrean, S.; Sandulescu, R.; Mora Diaz, N.; Dominguez, O.; Arcos, J.; Kauffmann, J.-M.

    2005-01-01

    The oxidation of several phenothiazine drugs (phenothiazine, promethazine hydrochloride, promazine hydrochloride, trimeprazine hydrochloride and ethopropazine hydrochloride) has been carried out in aqueous acidic media by electrochemical, chemical and enzymatic methods. The chemical oxidation was

  10. Recent Advances in Electrochemical Immunosensors

    Directory of Open Access Journals (Sweden)

    Benoît Piro

    2017-04-01

    Full Text Available Immunosensors have experienced a very significant growth in recent years, driven by the need for fast, sensitive, portable and easy-to-use devices to detect biomarkers for clinical diagnosis or to monitor organic pollutants in natural or industrial environments. Advances in the field of signal amplification using enzymatic reactions, nanomaterials such as carbon nanotubes, graphene and graphene derivatives, metallic nanoparticles (gold, silver, various oxides or metal complexes, or magnetic beads show how it is possible to improve collection, binding or transduction performances and reach the requirements for realistic clinical diagnostic or environmental control. This review presents these most recent advances; it focuses first on classical electrode substrates, then moves to carbon-based nanostructured ones including carbon nanotubes, graphene and other carbon materials, metal or metal-oxide nanoparticles, magnetic nanoparticles, dendrimers and, to finish, explore the use of ionic liquids. Analytical performances are systematically covered and compared, depending on the detection principle, but also from a chronological perspective, from 2012 to 2016 and early 2017.

  11. Electrochemical impedance spectroscopy of oxidized porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Mula, Guido, E-mail: guido.mula@unica.it [Dipartimento di Fisica, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Cagliari (Italy); Tiddia, Maria V. [Dipartimento di Fisica, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Cagliari (Italy); Ruffilli, Roberta [Nanochemistry, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova (Italy); Falqui, Andrea [Nanochemistry, Istituto Italiano di Tecnologia, Via Morego 30, 16163 Genova (Italy); Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, Cittadella Universitaria di Monserrato, S.P. 8 km 0.700, 09042 Cagliari (Italy); Palmas, Simonetta; Mascia, Michele [Dipartimento di Ingegneria Meccanica Chimica e dei Materiali, Università degli Studi di Cagliari, Piazza d' Armi, 09126 Cagliari (Italy)

    2014-04-01

    We present a study of the electrochemical oxidation process of porous silicon. We analyze the effect of the layer thickness (1.25–22 μm) and of the applied current density (1.1–11.1 mA/cm{sup 2}, values calculated with reference to the external samples surface) on the oxidation process by comparing the galvanostatic electrochemical impedance spectroscopy (EIS) measurements and the optical specular reflectivity of the samples. The results of EIS were interpreted using an equivalent circuit to separate the contribution of different sample parts. A different behavior of the electrochemical oxidation process has been found for thin and thick samples: whereas for thin samples the oxidation process is univocally related to current density and thickness, for thicker samples this is no more true. Measurements by Energy Dispersive Spectroscopy using a Scanning Electron Microscopy confirmed that the inhomogeneity of the electrochemical oxidation process is increased by higher thicknesses and higher currents. A possible explanation is proposed to justify the different behavior of thin and thick samples during the electrochemical process. - Highlights: • A multidisciplinary approach on porous Si electrochemical oxidation is proposed. • Electrochemical, optical, and structural characterizations are used. • Layer thickness and oxidation current effects are shown. • An explanation of the observed behavior is proposed.

  12. Nanomaterials-based electrochemical sensors for nitric oxide

    International Nuclear Information System (INIS)

    Dang, Xueping; Hu, Hui; Wang, Shengfu; Hu, Shengshui

    2015-01-01

    Electrochemical sensing has been demonstrated to represent an efficient way to quantify nitric oxide (NO) in challenging physiological environments. A sensing interface based on nanomaterials opens up new opportunities and broader prospects for electrochemical NO sensors. This review (with 141 refs.) gives a general view of recent advances in the development of electrochemical sensors based on nanomaterials. It is subdivided into sections on (i) carbon derived nanomaterials (such as carbon nanotubes, graphenes, fullerenes), (ii) metal nanoparticles (including gold, platinum and other metallic nanoparticles); (iii) semiconductor metal oxide nanomaterials (including the oxides of titanium, aluminum, iron, and ruthenium); and finally (iv) nanocomposites (such as those formed from carbon nanomaterials with nanoparticles of gold, platinum, NiO or TiO 2 ). The various strategies are discussed, and the advances of using nanomaterials and the trends in NO sensor technology are outlooked in the final section. (author)

  13. 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.

    Science.gov (United States)

    Gajski, Goran; Oreščanin, Višnja; Gerić, Marko; Kollar, Robert; Lovrenčić Mikelić, 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.

  14. Electrochemical analysis of metal oxides

    Czech Academy of Sciences Publication Activity Database

    Grygar, Tomáš; Bezdička, Petr; Hradil, David; Pikna, L.

    90-91, - (2003), s. 45-50 ISSN 1012-0394 Institutional research plan: CEZ:AV0Z4032918 Keywords : powder electroanalysis * Fe oxides * Mn oxides Subject RIV: CA - Inorganic Chemistry Impact factor: 0.687, year: 2003

  15. Electrochemical Oxidation of Glycerol Using Gold Electrode

    International Nuclear Information System (INIS)

    Mohamed Rozali Othman; Amirah Ahmad

    2015-01-01

    Cyclic voltammetry, potential linear V and chronocuolometry methods were carried out to gain electrochemical behavior of glycerol at a gold electrode. Potassium hydroxide and sulfuric acid were chosen to be the electrolyte for the electro-oxidation of this organic compound. Besides gold plate electrode, gold composite electrode (Au-PVC) was also used as the working electrode. The Au-PVC composite electrode was characterized by Scanning Electron Microscopy (SEM) to determine its morphological aspects before and after used in electrochemical oxidation of glycerol. In alkaline solution, the adsorption of hydroxide species onto the surface of both gold plate and composite Au-PVC electrodes occurs at potential around 500 mV vs SCE. However, at gold plate electrode, there was a small, broad peak before the drastic escalation of current densities which indicates the charge transfer of the chemisorbed OH - anion. In acidic media, the gold oxide was formed after potential 1.0 V. From the cyclic voltammogram glycerol undergo oxidation twice in potassium hydroxide at gold plate and Au-PVC composite electrodes, while in sulfuric acid, oxidation reaction happened once for glycerol on the gold plate electrode. Overall, electrochemical oxidation of glycerol was more effective in alkaline media. Tafel graph which plotted from potential linear V method shows that Au-PVC composite electrode is better than gold plate electrode for the electro-oxidation of glycerol in alkaline solution. Electrochemical oxidation of glycerol products as analyzed by Gas Chromatography-Mass Spectrometry (GC-MS) produced several carboxylic acids and phenolic compounds. (author)

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

    Science.gov (United States)

    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.

  17. Application of electrochemical advanced oxidation processes with a boron-doped diamond anode to degrade acidic solutions of Reactive Blue 15 (Turqueoise Blue) dye

    International Nuclear Information System (INIS)

    Solano, Aline Maria Sales; Martínez-Huitle, Carlos Alberto; Garcia-Segura, Sergi; El-Ghenymy, Abdellatif

    2016-01-01

    Highlights: • Degradation of Reactive Blue 15 solution at pH 3.0 by electrochemical oxidation, electro-Fenton and photoelectro-Fenton. • Hard destruction of the dye and its products by BDD(·OH) and much more rapidly by ·OH. • 94% mineralization by the most powerful photoelectro-Fenton at 66.7 mA cm"−"2, with acetic acid accumulation. • 25 aromatics and heteroaromatics, 30 hydroxylated derivatives and 4 carboxylic acids as products. • Release of Cl"−, SO_4"2"− and pre-eminently NO_3"− during dye mineralization. - Abstract: The degradation of the copper-phthalocyanine dye Reactive Blue 15 dye in sulfate medium has been comparatively studied by electrochemical oxidation with electrogenerated H_2O_2 (EO-H_2O_2), electro-Fenton (EF) and photoelectro-Fenton (PEF). Experiments with 100 cm"3 solutions of 0.203 mmol dm"−"3 dye were performed with a stirred tank reactor containing a boron-doped diamond (BDD) anode and an air-diffusion cathode for continuous H_2O_2 production. Experimental conditions of pH 3.0 and 0.50 mmol dm"−"3 Fe"2"+ as catalyst were found optimal for the EF process by the predominant oxidation with hydroxyl radicals formed in the bulk from Fenton’s reaction between added Fe"2"+ and generated H_2O_2. The kinetics of Reactive Blue 15 abatement was followed by reversed-phase HPLC and always obeyed a pseudo-first-order reaction. The decolorization rate in EO-H_2O_2 was much lower than dye decay due to the formation of large quantities of colored intermediates under the action of hydroxyl radicals generated at the BDD anode from water oxidation. In contrast, the color and dye removals were much more rapid in EF and PEF by the most efficient oxidation of hydroxyl radicals produced from Fenton’s reaction. PEF was the most powerful treatment owing to the photolytic action of UVA irradiation, yielding 94% mineralization after 360 min at 66.7 mA cm"−"2. The effect of current density over the performance of all methods was examined. LC

  18. Electrochemical oxidation and detection of sodium urate in alkaline ...

    African Journals Online (AJOL)

    Electrochemical behaviour of copper oxides electrode in the presence of sodium urate was investigated. The correlation between the anodic oxidation and the amperometric detection of sodium urate in the alkaline medium on copper oxides electrode was analysed by cyclic voltammetry (CV) and electrochemical ...

  19. Synthesis of magnetite nanoparticles using electrochemical oxidation

    Directory of Open Access Journals (Sweden)

    Ye. Ya. Levitin

    2014-08-01

    Full Text Available The monodisperse magnetite nanoparticles are promising for use in the biomedical industry for targeted drug delivery, cell separation and biochemical products, Magnetic Resonance Imaging, immunological studies, etc. Classic method for the synthesis of magnetite is the chemical condensation Elmore’s, it is simple and cheap, but it is complicated by the formation of side compounds which impair the magnetic properties of the final product. Biological and medical purposes require high purity magnetite nanoparticles. Electrochemical methods of producing nanoparticles of magnetite acquire significant spread. The kinetics of electrochemical processes are a function of a larger number of parameters than the kinetics of conventional chemical reaction, thus electrochemical reactions can be thinner and more completely adjusted to give a predetermined size nanoparticles. In the kinetics of the electrochemical oxidation and reduction the important role is played by the nature of the electrode. In many industrial processes, it is advisable to use lead dioxide anodes with titanium current lead. Purpose of the work To determine the optimum conditions of electrochemical oxidation of Fe2+ Fe3+to produce magnetite with high purity and improved magnetic characteristics. Materials and methods Electrochemical studies were carried out in a glass cell ЯСЭ-2 using a potentiostat ПИ-50-1.1 and a recording device ПДА1. Reference electrode - silver chloride ЭВЛ1М 3.1, potentials listed on the hydrogen scale. The test solution contained 80 g/ l FeSO4×7H2O and H2SO4(to pH 1. The pH of the solution was measured with a pH–meter « рН–150». Concentration ratio of Fe3+/Fe2+in the solution was measured by permanganometric method. Magnetite particle sizes were measured by an electron microscope computer ЭВМ-100Л, an increasing is 2×105. Saturation magnetization was evaluated by the magnetization curve, for the measured sample in the field with strength

  20. Electrochemical Thinning for Anodic Aluminum Oxide and Anodic Titanium Oxide

    Energy Technology Data Exchange (ETDEWEB)

    Lee, In Hae; Jo, Yun Kyoung; Kim, Yong Tae; Tak, Yong Sug; Choi, Jin Sub [Inha University, Incheon (Korea, Republic of)

    2012-05-15

    For given electrolytes, different behaviors of anodic aluminum oxide (AAO) and anodic titanium oxide (ATO) during electrochemical thinning are explained by ionic and electronic current modes. Branched structures are unavoidably created in AAO since the switch of ionic to electronic current is slow, whereas the barrier oxide in ATO is thinned without formation of the branched structures. In addition, pore opening can be possible in ATO if chemical etching is performed after the thinning process. The thinning was optimized for complete pore opening in ATO and potential-current behavior is interpreted in terms of ionic current-electronic current switching.

  1. Spectro-electrochemical and DFT study of tenoxicam metabolites formed by electrochemical oxidation

    International Nuclear Information System (INIS)

    Ramírez-Silva, M.T.; Guzmán-Hernández, D.S.; Galano, A.; Rojas-Hernández, A.; Corona-Avendaño, S.; Romero-Romo, M.; Palomar-Pardavé, M.

    2013-01-01

    Highlights: • Tenoxicam deprotonation and electrochemical oxidation were studied. • Both spectro-electrochemical and theoretical DFT studies were considered. • It was found that the ampholitic species of tenoxicam is a zwitterion. • Electrochemical oxidation of tenoxicam yields two non-electroactive products. • The nature of these fragments was further confirmed by a chromatography study. -- Abstract: From experimental (spectro-electrochemical) and theoretical (DFT) studies, the mechanisms of tenoxicam deprotonation and electrochemical oxidation were assessed. From these studies, new insights on the nature of the ampholitic species involved during tenoxicam's deprotonation in aqueous solution are presented; see scheme A. Moreover, it is shown that, after the analysis of two different reaction schemes that involve up to 10 different molecules and 12 reaction paths, the electrochemical oxidation of tenoxicam, yields two non-electroactive products that are predominately formed by its fragmentation, after the loss of two electrons. The nature of these fragments was further confirmed by a chromatography study

  2. pH-sensor properties of electrochemically grown iridium oxide

    NARCIS (Netherlands)

    Olthuis, Wouter; Robben, M.A.M.; Bergveld, Piet; Bos, M.; van der Linden, 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

  3. Diversity in electrochemical oxidation of dihydroxybenzenes in the ...

    Indian Academy of Sciences (India)

    Abstract. Electrochemical oxidation of some catechol derivatives (1a–e) have been studied in water/ acetonitrile solution containing 1-methylindole (3) as a nucleophile, using cyclic voltammetry and controlled- potential coulometry. An interesting diversity in the mechanisms has been observed in electrochemical oxidation ...

  4. Degradation of pharmaceutical beta-blockers by electrochemical advanced oxidation processes using a flow plant with a solar compound parabolic collector.

    Science.gov (United States)

    Isarain-Chávez, Eloy; Rodríguez, Rosa María; Cabot, Pere Lluís; Centellas, Francesc; Arias, Conchita; Garrido, José Antonio; Brillas, Enric

    2011-08-01

    The degradation of the beta-blockers atenolol, metoprolol tartrate and propranolol hydrochloride was studied by electro-Fenton (EF) and solar photoelectro-Fenton (SPEF). Solutions of 10 L of 100 mg L⁻¹ of total organic carbon of each drug in 0.1 M Na₂SO₄ with 0.5 mM Fe²⁺ of pH 3.0 were treated in a recirculation flow plant with an electrochemical reactor coupled with a solar compound parabolic collector. Single Pt/carbon felt (CF) and boron-doped diamond (BDD)/air-diffusion electrode (ADE) cells and combined Pt/ADE-Pt/CF and BDD/ADE-Pt/CF cells were used. SPEF treatments were more potent with the latter cell, yielding 95-97% mineralization with 100% of maximum current efficiency and energy consumptions of about 0.250 kWh g TOC⁻¹. However, the Pt/ADE-Pt/CF cell gave much lower energy consumptions of about 0.080 kWh g TOC⁻¹ with slightly lower mineralization of 88-93%, then being more useful for its possible application at industrial level. The EF method led to a poorer mineralization and was more potent using the combined cells by the additional production of hydroxyl radicals (•OH) from Fenton's reaction from the fast Fe²⁺ regeneration at the CF cathode. Organics were also more rapidly destroyed at BDD than at Pt anode. The decay kinetics of beta-blockers always followed a pseudo first-order reaction, although in SPEF, it was accelerated by the additional production of •OH from the action of UV light of solar irradiation. Aromatic intermediates were also destroyed by hydroxyl radicals. Ultimate carboxylic acids like oxalic and oxamic remained in the treated solutions by EF, but their Fe(III) complexes were photolyzed by solar irradiation in SPEF, thus explaining its higher oxidation power. NO₃⁻ was the predominant inorganic ion lost in EF, whereas the SPEF process favored the production of NH₄⁺ ion and volatile N-derivatives. Copyright © 2011 Elsevier Ltd. All rights reserved.

  5. Electrochemical Oxidation of Propene with a LSF15/CGO10 Electrochemical Reactor

    DEFF Research Database (Denmark)

    Ippolito, Davide; Kammer Hansen, Kent

    2014-01-01

    A porous electrochemical reactor, made of La0.85Sr0.15FeO3 (LSF) as electrode and Ce0.9Gd0.1O1.95 (CGO) as electrolyte, was studied for the electrochemical oxidation of propene over a wide range of temperatures. Polarization was found to enhance propene oxidation rate. Ce0.9Gd0.1O1.95 was used...... as infiltration material to enhance the effect of polarization on propene oxidation rate, especially at low temperatures. The influence of infiltrated material, as a function of heat treatment, on the reactor electrochemical behavior has been evaluated by using electrochemical impedance spectroscopy...... in suppressing the competing oxygen evolution reaction and promoting the oxidation of propene under polarization, with faradaic efficiencies above 70% at 250◦C. © 2014 The Electrochemical Society....

  6. Effect of Amine Adlayer on Electrochemical Uric Acid Sensor Conducted on Electrochemically Reduced Graphene Oxide

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sumi; Kim, Kyuwon [Incheon National University, Incheon (Korea, Republic of)

    2016-03-15

    The electrochemical biosensing efficiency of uric acid (UA) detection on an electrochemically reduced graphene oxide (ERGO)-decorated electrode surface was studied by using various amine linkers used to immobilize ERGO. The amine linkers aminoethylphenyldiazonium , 2,2'-(ethylenedioxy)bis(ethylamine), 3-aminopro-pyltriethoxysilane, and polyethyleneimine were coated on indium-tin-oxide electrode surfaces through chemical or electrochemical deposition methods. ERGO-decorated surfaces were prepared by the electrochemical reduction of graphene oxide (GO), which was immobilized on the amine-coated electrode surfaces through the electrostatic interaction between GO and the ammonium ion of the linker on the surface. We monitored the sensing results of electrochemical UA detection with differential pulse voltammetry. The ERGO-modified surface presented electrocatalytic oxidation of UA and ascorbic acid. Among the different amines tested, 3-aminopropyltriethoxysilane provided the best biosensing performance in terms of sensitivity and reproducibility.

  7. Effect of Amine Adlayer on Electrochemical Uric Acid Sensor Conducted on Electrochemically Reduced Graphene Oxide

    International Nuclear Information System (INIS)

    Park, Sumi; Kim, Kyuwon

    2016-01-01

    The electrochemical biosensing efficiency of uric acid (UA) detection on an electrochemically reduced graphene oxide (ERGO)-decorated electrode surface was studied by using various amine linkers used to immobilize ERGO. The amine linkers aminoethylphenyldiazonium , 2,2'-(ethylenedioxy)bis(ethylamine), 3-aminopro-pyltriethoxysilane, and polyethyleneimine were coated on indium-tin-oxide electrode surfaces through chemical or electrochemical deposition methods. ERGO-decorated surfaces were prepared by the electrochemical reduction of graphene oxide (GO), which was immobilized on the amine-coated electrode surfaces through the electrostatic interaction between GO and the ammonium ion of the linker on the surface. We monitored the sensing results of electrochemical UA detection with differential pulse voltammetry. The ERGO-modified surface presented electrocatalytic oxidation of UA and ascorbic acid. Among the different amines tested, 3-aminopropyltriethoxysilane provided the best biosensing performance in terms of sensitivity and reproducibility.

  8. Mediated electrochemical oxidation of mixed wastes

    International Nuclear Information System (INIS)

    Chiba, Z.

    1993-04-01

    The Mediated Electrochemical Oxidation (MEO) process was studied for destroying low-level combustible mixed wastes at Rocky Flats Plant. Tests were performed with non-radioactive surrogate materials: Trimsol for contaminated cutting oils, and reagent-grade cellulose for contaminated 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 tests were also carried out in the small-scale system with cellulose. Operating and system parameters that were studied were: use of a silver-nitric acid versus a cobalt-sulfuric acid system, effect of electrolyte temperature, effect of acid concentration, and effect of current density. Destruction and coulombic efficiencies were calculated using data obtained from continuous carbon dioxide monitors and total organic carbon (TOC) analysis of electrolyte samples. For Trimsol, the best performance was achieved with the silver-nitrate system at high acid concentrations, temperatures, and current densities. Destruction efficiencies of 99% or greater, and coulombic efficiencies up to 70% were obtained. For the cellulose, high destruction efficiencies and reasonable coulombic efficiencies were obtained for both silver-nitrate and cobalt-sulfate systems

  9. Electrochemical reduction of cerium oxide into metal

    Energy Technology Data Exchange (ETDEWEB)

    Claux, Benoit [CEA, Valduc, F-21120 Is-sur-Tille (France); Universite de Grenoble, LEPMI-ENSEEG, 1130 rue de la Piscine, BP75, F-38402 St Martin d' Heres Cedex (France); Serp, Jerome, E-mail: jerome.serp@cea.f [CEA, Valduc, F-21120 Is-sur-Tille (France); Fouletier, Jacques [Universite de Grenoble, LEPMI-ENSEEG, 1130 rue de la Piscine, BP75, F-38402 St Martin d' Heres Cedex (France)

    2011-02-28

    The Fray Farthing and Chen (FFC) and Ono and Suzuki (OS) processes were developed for the reduction of titanium oxide to titanium metal by electrolysis in high temperature molten alkali chloride salts. The possible transposition to CeO{sub 2} reduction is considered in this study. Present work clarifies, by electro-analytical techniques, the reduction pathway leading to the metal. The reduction of CeO{sub 2} into metal was feasible via an indirect mechanism. Electrolyses on 10 g of CeO{sub 2} were carried out to evaluate the electrochemical process efficiency. Ca metal is electrodeposited at the cathode from CaCl{sub 2}-KCl solvent and reacts chemically with ceria to form not only metallic cerium, but also cerium oxychloride.

  10. Innovative oxide materials for electrochemical energy conversion and oxygen separation

    Science.gov (United States)

    Belousov, V. V.

    2017-10-01

    Ion-conducting solid metal oxides are widely used in high-temperature electrochemical devices for energy conversion and oxygen separation. However, liquid metal oxides possessing unique electrochemical properties still remain of limited use. The review demonstrates the potential for practical applications of molten oxides. The transport properties of molten oxide materials are discussed. The emphasis is placed on the chemical diffusion of oxygen in the molten oxide membrane materials for electrochemical energy conversion and oxygen separation. The thermodynamics of these materials is considered. The dynamic polymer chain model developed to describe the oxygen ion transport in molten oxides is discussed. Prospects for further research into molten oxide materials are outlined. The bibliography includes 145 references.

  11. Aerobic and Electrochemical Oxidations with N-Oxyl Reagents

    Science.gov (United States)

    Miles, Kelsey C.

    Selective oxidation of organic compounds represents a significant challenge for chemical transformations. Oxidation methods that utilize nitroxyl catalysts have become increasingly attractive and include Cu/nitroxyl and nitroxyl/NO x co-catalyst systems. Electrochemical activation of nitroxyls is also well known and offers an appealing alternative to the use of chemical co-oxidants. However, academic and industrial organic synthetic communities have not widely adopted electrochemical methods. Nitroxyl catalysts facilitate effective and selective oxidation of alcohols and aldehydes to ketones and carboxylic acids. Selective benzylic, allylic, and alpha-heteroatom C-H abstraction can also be achieved with nitroxyls and provides access to oxygenated products when used in combination with molecular oxygen as a radical trap. This thesis reports various chemical and electrochemical oxidation methods that were developed using nitroxyl mediators. Chapter 1 provides a short review on practical aerobic alcohol oxidation with Cu/nitroxyl and nitroxyl/NO x systems and emphasizes the utility of bicyclic nitroxyls as co-catalysts. In Chapter 2, the combination of these bicyclic nitroxyls with NOx is explored for development of a mild oxidation of alpha-chiral aryl aldehydes and showcases a sequential asymmetric hydroformylation/oxidation method. Chapter 3 reports the synthesis and characterization of two novel Cu/bicyclic nitroxyl complexes and the electronic structure analysis of these complexes. Chapter 4 highlights the electrochemical activation of various nitroxyls and reports an in-depth study on electrochemical alcohol oxidation and compares the reactivity of nitroxyls under electrochemical or chemical activation. N-oxyls can also participate in selective C-H abstraction, and Chapter 5 reports the chemical and electrochemical activation of N-oxyls for radical-mediated C-H oxygenation of (hetero)arylmethanes. For these electrochemical transformations, the development of

  12. Electrochemical activity of heavy metal oxides in the process of ...

    Indian Academy of Sciences (India)

    Unknown

    2002-02-02

    Feb 2, 2002 ... Electrochemical activity of heavy metal oxides in the process of chloride induced .... represents the protective barrier moderating the chloride attack which ... inhibitors and their influence on the physical properties of. Portland ...

  13. Kinetic study on electrochemical oxidation of catechols in the ...

    Indian Academy of Sciences (India)

    glassy carbon electrode in different experimental conditions. The electrogenerated ... cancer activities.5 Catechols can be easily oxidized electrochemically to ... from unity and approaches to zero in basic solution. This behavior is related to the ...

  14. effect of electrochemical oxidation of a viscose rayon based ...

    African Journals Online (AJOL)

    DJFLEX

    KEYWORDS: Viscose rayon based activated carbon cloth; Sorption isotherms; Electrochemical oxidation; Arsenic .... (AAS ) in acetylene-air flame emission mode. 2.9. Quality ..... of the EO ACC thereby restricting the number of binding sites for ...

  15. Electrochemical decontamination of waters by advanced oxidation processes (aops): Case of the mineralization of 2,4,5-t on bdd electrode

    OpenAIRE

    Birame Boye; Enric Brillas; Beatrice Marselli; Pierre-Alain Michaud; Christos Comninellis; Mor Marième Dieng

    2004-01-01

    In the present work, herbicide 2,4,5-trichlorophenoxyacetic acid, more commonly known as 2,4,5-T herbicide, has been completely mineralized (i.e. transformed into CO2 and H2O) in saturated aqueous solutions using a semi-industrial electrochemical cell that contains a boron doped diamond anode and a zirconium cathode. We have performed cyclic voltammetry, chronoamperometry and bulk electrolysis to give the optimization characteristics of the degradation of such a compound and its by-products. ...

  16. Smart electrochemical biosensors: From advanced materials to ultrasensitive devices

    Energy Technology Data Exchange (ETDEWEB)

    Sadik, Omowunmi A., E-mail: osadik@binghamton.ed [Department of Chemistry, Center for Advanced Sensors and Environmental Monitoring (CASE), State University of New York-Binghamton, P.O. Box 6000, Binghamton, NY 13902 (United States); Mwilu, Samuel K.; Aluoch, Austin [Department of Chemistry, Center for Advanced Sensors and Environmental Monitoring (CASE), State University of New York-Binghamton, P.O. Box 6000, Binghamton, NY 13902 (United States)

    2010-05-30

    The specificity, simplicity, and inherent miniaturization afforded by advances in modern electronics have allowed electrochemical sensors to rival the most advanced optical protocols. One major obstacle in implementing electrochemistry for studying biomolecular reaction is its inadequate sensitivity. Recent reports however showed unprecedented sensitivities for biomolecular recognition using enhanced electronic amplification provided by new classes of electrode materials (e.g. carbon nanotubes, metal nanoparticles, and quantum dots). Biosensor technology is one area where recent advances in nanomaterials are pushing the technological limits of electrochemical sensitivities, thus allowing for the development of new sensor chemistries and devices. This work focuses on our recent work, based on metal-enhanced electrochemical detection, and those of others in combining advanced nanomaterials with electrochemistry for the development of smart sensors for proteins, nucleic acids, drugs and cancer cells.

  17. Smart electrochemical biosensors: From advanced materials to ultrasensitive devices

    International Nuclear Information System (INIS)

    Sadik, Omowunmi A.; Mwilu, Samuel K.; Aluoch, Austin

    2010-01-01

    The specificity, simplicity, and inherent miniaturization afforded by advances in modern electronics have allowed electrochemical sensors to rival the most advanced optical protocols. One major obstacle in implementing electrochemistry for studying biomolecular reaction is its inadequate sensitivity. Recent reports however showed unprecedented sensitivities for biomolecular recognition using enhanced electronic amplification provided by new classes of electrode materials (e.g. carbon nanotubes, metal nanoparticles, and quantum dots). Biosensor technology is one area where recent advances in nanomaterials are pushing the technological limits of electrochemical sensitivities, thus allowing for the development of new sensor chemistries and devices. This work focuses on our recent work, based on metal-enhanced electrochemical detection, and those of others in combining advanced nanomaterials with electrochemistry for the development of smart sensors for proteins, nucleic acids, drugs and cancer cells.

  18. Technology advancement of the electrochemical CO2 concentrating process

    Science.gov (United States)

    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).

  19. Electrochemical promotion of sulfur dioxide catalytic oxidation

    DEFF Research Database (Denmark)

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

    2000-01-01

    investigation was to study a possible non-Faradaic electrochemical promotion of the liquid-phase catalytic reaction. It has been shown that there are two negative potential promotion areas with maximum effects at approximately -0.1 and -0.2 V, and one positive potential promotion area with the maximum effect...... between 0.1 and 0.3 V. There were no Faradaic reactions in the negative polarization region, and there was an anodic current which was less than 16% of the theoretical value for an exclusively Faradaic SO2 oxidation. Therefore the promotion effects at negative polarization are completely non-Faradaic. All...... the promotion effects have been explained as mainly due to charging of the electric double layer at the gold electrode. The effect at -0.2 V also depends on the V2O5 concentration and is more pronounced at higher V2O5 concentrations. This has been ascribed to a destruction of the vanadium polymeric chains...

  20. Cuprous oxide thin films grown by hydrothermal electrochemical deposition technique

    International Nuclear Information System (INIS)

    Majumder, M.; Biswas, I.; Pujaru, S.; Chakraborty, A.K.

    2015-01-01

    Semiconducting cuprous oxide films were grown by a hydrothermal electro-deposition technique on metal (Cu) and glass (ITO) substrates between 60 °C and 100 °C. X-ray diffraction studies reveal the formation of cubic cuprous oxide films in different preferred orientations depending upon the deposition technique used. Film growth, uniformity, grain size, optical band gap and photoelectrochemical response were found to improve in the hydrothermal electrochemical deposition technique. - Highlights: • Cu 2 O thin films were grown on Cu and glass substrates. • Conventional and hydrothermal electrochemical deposition techniques were used. • Hydrothermal electrochemical growth showed improved morphology, thickness and optical band gap

  1. Electrochemical and partial oxidation of methane

    Science.gov (United States)

    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

  2. From Two-Phase to Three-Phase: The New Electrochemical Interface by Oxide Electrocatalysts

    Science.gov (United States)

    Xu, Zhichuan J.

    2018-03-01

    Electrochemical reactions typically occur at the interface between a solid electrode and a liquid electrolyte. The charge exchange behaviour between these two phases determines the kinetics of electrochemical reactions. In the past few years, significant advances have been made in the development of metal oxide electrocatalysts for fuel cell and electrolyser reactions. However, considerable gaps remain in the fundamental understanding of the charge transfer pathways and the interaction between the metal oxides and the conducting substrate on which they are located. In particular, the electrochemical interfaces of metal oxides are significantly different from the traditional (metal) ones, where only a conductive solid electrode and a liquid electrolyte are considered. Oxides are insulating and have to be combined with carbon as a conductive mediator. This electrode configuration results in a three-phase electrochemical interface, consisting of the insulating oxide, the conductive carbon, and the liquid electrolyte. To date, the mechanistic insights into this kind of non-traditional electrochemical interface remain unclear. Consequently conventional electrochemistry concepts, established on classical electrode materials and their two-phase interfaces, are facing challenges when employed for explaining these new electrode materials. [Figure not available: see fulltext.

  3. Electrochemical decontamination of waters by advanced oxidation processes (aops: Case of the mineralization of 2,4,5-t on bdd electrode

    Directory of Open Access Journals (Sweden)

    Birame Boye

    2004-12-01

    Full Text Available In the present work, herbicide 2,4,5-trichlorophenoxyacetic acid, more commonly known as 2,4,5-T herbicide, has been completely mineralized (i.e. transformed into CO2 and H2O in saturated aqueous solutions using a semi-industrial electrochemical cell that contains a boron doped diamond anode and a zirconium cathode. We have performed cyclic voltammetry, chronoamperometry and bulk electrolysis to give the optimization characteristics of the degradation of such a compound and its by-products. Bulk electrolysis in the potential region of electrolyte decomposition leads to the complete destruction of 2,4,5-T and its degradation intermediates by means of the electrogeneration of the highly reactive hydroxyl radicals. The evolution of the chemical oxygen demand (COD and the instant current efficiency (ICE during the degradation process is perfectly predicted by a theoretical mathematical model. HPLC and GC-MS have also been performed to highlight the evolution of the mother product and its degradation intermediates. Kinetic analysis of the obtained results has shown a fast destruction of the mother herbicide asserting a diffusion-controlled process. 2,4,5-trichlorophenol and quinone-based organic compounds have been depicted as aromatic intermediates, all of them transformed into short chains carboxylic acids before complete mineralization happens.

  4. Electrochemical oxidation of nitrite on nanodiamond powder electrode

    Energy Technology Data Exchange (ETDEWEB)

    Chen, L.H.; Zang, J.B.; Wang, Y.H.; Bian, L.Y. [State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004 (China); College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China)

    2008-03-10

    Nanodiamond (ND) powder electrodes were fabricated and the electrochemical properties were investigated in the solution containing nitrite in this article. This electrode exhibits substantial catalytic ability toward the oxidation of nitrite anions. The electrochemical oxidation mechanism of nitrite on the ND powder electrode is discussed. The oxidation of NaNO{sub 2} is a two-electron transfer process. The electrode reaction rate constant k is estimated to be 2.013 x 10{sup -4} cm/s and (1 - {alpha})n{sub {alpha}} is 0.1643. The peak current increases linearly with the rising of the concentration of NaNO{sub 2}. (author)

  5. Oxidative electrochemical aryl C-C coupling of spiropyrans

    NARCIS (Netherlands)

    Ivashenko, Oleksii; van Herpt, Jochem T.; Rudolf, Petra; Feringa, Ben L.; Browne, Wesley R.

    2013-01-01

    The isolation and definitive assignment of the species formed upon electrochemical oxidation of nitro-spiropyran (SP) is reported. The oxidative aryl C-C coupling at the indoline moiety of the SP radical cation to form covalent dimers of the ring-closed SP form is demonstrated. The coupling is

  6. Electrochemical Oxidation of Phenol using a Flow-through Micro ...

    African Journals Online (AJOL)

    The electrochemical oxidation of phenol to benzoquinone followed by the reduction to hydroquinone and catechol was demonstrated by constructing a three-dimensional porous micro-flow cell from lead dioxideand lead. The electrodes were made by using the principles of curing and formation of lead oxide material that ...

  7. Degradation of the beta-blocker propranolol by electrochemical advanced oxidation processes based on Fenton's reaction chemistry using a boron-doped diamond anode

    Energy Technology Data Exchange (ETDEWEB)

    Isarain-Chavez, Eloy; Rodriguez, Rosa Maria; Garrido, Jose Antonio; Arias, Conchita; Centellas, Francesc; Cabot, Pere Lluis [Laboratori d' Electroquimica dels Materials i del Medi Ambient, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Brillas, Enric, E-mail: brillas@ub.ed [Laboratori d' Electroquimica dels Materials i del Medi Ambient, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain)

    2010-12-15

    The electro-Fenton (EF) and photoelectro-Fenton (PEF) degradation of solutions of the beta-blocker propranolol hydrochloride with 0.5 mmol dm{sup -3} Fe{sup 2+} at pH 3.0 has been studied using a single cell with a boron-doped diamond (BDD) anode and an air diffusion cathode (ADE) for H{sub 2}O{sub 2} electrogeneration and a combined cell containing the above BDD/ADE pair coupled in parallel to a Pt/carbon felt (CF) cell. This naphthalene derivative can be mineralized by both methods with a BDD anode. Almost overall mineralization is attained for the PEF treatments, more rapidly with the combined system due to the generation of higher amounts of hydroxyl radical from Fenton's reaction by the continuous Fe{sup 2+} regeneration at the CF cathode, accelerating the oxidation of organics to Fe(III)-carboxylate complexes that are more quickly photolyzed by UVA light. The homologous EF processes are less potent giving partial mineralization. The effect of current density, pH and Fe{sup 2+} and drug concentrations on the oxidation power of PEF process in combined cell is examined. Propranolol decay follows a pseudo first-order reaction in most cases. Aromatic intermediates such as 1-naphthol and phthalic acid and generated carboxylic acids such as maleic, formic, oxalic and oxamic are detected and quantified by high-performance liquid chromatography. The chloride ions present in the starting solution are slowly oxidized at the BDD anode. In PEF treatments, all initial N of propranolol is completely transformed into inorganic ions, with predominance of NH{sub 4}{sup +} over NO{sub 3}{sup -} ion.

  8. ADVANCED OXIDATION PROCESSES FOR FOOD INDUSTRIAL WASTEWATER DECONTAMINATION

    Directory of Open Access Journals (Sweden)

    Dorota Krzemińska

    2015-02-01

    Full Text Available High organic matter content is a basic problem in food industry wastewaters. Typically, the amount and composition of the effluent varies considerably. In the article four groups of advanced processes and their combination of food industry wastewater treatment have been reviewed: electrochemical oxidation (EC, Fenton’s process, ozonation of water and photocatalytic processes. All advanced oxidation processes (AOP`s are characterized by a common chemical feature: the capability of exploiting high reactivity of HO• radicals in driving oxidation processes which are suitable for achieving decolonization and odour reduction, and the complete mineralization or increase of bioavailability of recalcitrant organic pollutants.

  9. Ammonia removal in electrochemical oxidation: Mechanism and pseudo-kinetics

    International Nuclear Information System (INIS)

    Li Liang; Liu Yan

    2009-01-01

    This paper investigated the mechanism and pseudo-kinetics for removal of ammonia by electrochemical oxidation with RuO 2 /Ti anode using batch tests. The results show that the ammonia oxidation rates resulted from direct oxidation at electrode-liquid interfaces of the anode by stepwise dehydrogenation, and from indirect oxidation by hydroxyl radicals were so slow that their contribution to ammonia removal was negligible under the condition with Cl - . The oxidation rates of ammonia ranged from 1.0 to 12.3 mg N L -1 h -1 and efficiency reached nearly 100%, primarily due to the indirect oxidation of HOCl, and followed pseudo zero-order kinetics in electrochemical oxidation with Cl - . About 88% ammonia was removed from the solution. The removed one was subsequently found in the form of N 2 in the produced gas. The rate at which Cl - lost electrons at the anode was a major factor in the overall ammonia oxidation. Current density and Cl - concentration affected the constant of the pseudo zero-order kinetics, expressed by k = 0.0024[Cl - ] x j. The ammonia was reduced to less than 0.5 mg N L -1 after 2 h of electrochemical oxidation for the effluent from aerobic or anaerobic reactors which treated municipal wastewater. This result was in line with the strict discharge requirements

  10. Destination of organic pollutants during electrochemical oxidation of biologically-pretreated dye wastewater using boron-doped diamond anode.

    Science.gov (United States)

    Zhu, Xiuping; Ni, Jinren; Wei, Junjun; Xing, Xuan; Li, Hongna

    2011-05-15

    Electrochemical oxidation of biologically-pretreated dye wastewater was performed in a boron-doped diamond (BDD) anode system. After electrolysis of 12h, the COD was decreased from 532 to 99 mg L(-1) (destination of organic pollutants during electrochemical oxidation process was carefully investigated by molecular weight distribution measurement, resin fractionation, ultraviolet-visible spectroscopy, HPLC and GC-MS analysis, and toxicity test. As results, most organic pollutants were completely removed by electrochemical oxidation and the rest was primarily degraded to simpler compounds (e.g., carboxylic acids and short-chain alkanes) with less toxicity, which demonstrated that electrochemical oxidation of biologically-pretreated dye wastewater with BDD anode was very effective and safe. Especially, the performance of BDD anode system in degradation of large molecular organics such as humic substances makes it very promising in practical applications as an advanced treatment of biologically-pretreated wastewaters. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Destination of organic pollutants during electrochemical oxidation of biologically-pretreated dye wastewater using boron-doped diamond anode

    International Nuclear Information System (INIS)

    Zhu, Xiuping; Ni, Jinren; Wei, Junjun; Xing, Xuan; Li, Hongna

    2011-01-01

    Electrochemical oxidation of biologically-pretreated dye wastewater was performed in a boron-doped diamond (BDD) anode system. After electrolysis of 12 h, the COD was decreased from 532 to 99 mg L -1 ( -1 , the National Discharge Standard of China). More importantly, the destination of organic pollutants during electrochemical oxidation process was carefully investigated by molecular weight distribution measurement, resin fractionation, ultraviolet-visible spectroscopy, HPLC and GC-MS analysis, and toxicity test. As results, most organic pollutants were completely removed by electrochemical oxidation and the rest was primarily degraded to simpler compounds (e.g., carboxylic acids and short-chain alkanes) with less toxicity, which demonstrated that electrochemical oxidation of biologically-pretreated dye wastewater with BDD anode was very effective and safe. Especially, the performance of BDD anode system in degradation of large molecular organics such as humic substances makes it very promising in practical applications as an advanced treatment of biologically-pretreated wastewaters.

  12. Effect of oxide ion concentration on the electrochemical oxidation of carbon in molten LiCl

    International Nuclear Information System (INIS)

    Yun, J. W.; Choi, I. K.; Park, Y. S.; Kim, W. H.

    2001-01-01

    The continuous measurement of lithium oxide concentration was required in DOR (Direct Oxide Reduction) process, which converts spent nuclear fuel to metal form, for the reactivity monitor and effective control of the process. The concentration of lithium oxide was measured by the electrochemical method, which was based on the phenomenon that carbon atoms of glassy carbon electrode electrochemically react with oxygen ions of lithium oxide in molten LiCl medium. From the results of electrode polarization experiments, the trend of oxidation rate of carbon atoms was classified into two different regions, which were proportional and non-proportional ones, dependent on the amount of lithium oxide. Below about 2.5 wt % Li 2 O, as the carbon atom ionization rate was fast enough for reacting with diffusing lithium oxide to the surface of carbon electrode. In this concentration range, the oxidation rate of carbon atoms was controlled by the diffusion of lithium oxide, and the concentration of lithium oxide could be measured by electrochemical method. But, above 2.5 wt % Li 2 O, the oxidation rate of carbon atoms was controlled by the applied electrochemical potential, because the carbon atom ionization rate was suppressed by the huge amounts of diffusing Li 2 O. Above this concentration, the electrochemical method was not applicable to determine the concentration of lithium oxide

  13. Improved Electrochemical Detection of Zinc Ions Using Electrode Modified with Electrochemically Reduced Graphene Oxide

    Czech Academy of Sciences Publication Activity Database

    Kudr, J.; Richtera, L.; Nejdl, L.; Xhaxhiu, K.; Vítek, Petr; Rutkay-Nedecky, B.; Hynek, D.; Kopel, P.; Adam, V.; Kižek, R.

    2016-01-01

    Roč. 9, č. 1 (2016), UNSP 31 ISSN 1996-1944 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:67179843 Keywords : carbon * cyclic voltammetry * electrochemical impedance spectroscopy * electrochemistry * graphene oxide * heavy metal detection * reduced graphene oxide Subject RIV: CG - Electrochemistry OBOR OECD: Electrochemistry (dry cells, batteries, fuel cells, corrosion metals , electrolysis) Impact factor: 2.654, year: 2016

  14. Treatment of Radioactive Organic Wastes by an Electrochemical Oxidation

    International Nuclear Information System (INIS)

    Kim, K.H.; Ryue, Y.G.; Kwak, K.K.; Hong, K.P.; Kim, D.H.

    2007-01-01

    A waste treatment system by using an electrochemical oxidation (MEO, Mediated Electrochemical Oxidation) was installed at KAERI (Korea Atomic Energy Research Institute) for the treatment of radioactive organic wastes, especially EDTA (Ethylene Diamine Tetraacetic Acid) generated during the decontamination activity of nuclear installations. A cerium and silver mediated electrochemical oxidation technique method has been developed as an alternative for an incineration process. An experiment to evaluate the applicability of the above two processes and to establish the conditions to operate the pilot-scale system has been carried out by changing the concentration of the catalyst and EDTA, the operational current density, the operating temperature, and the electrolyte concentration. As for the results, silver mediated oxidation was more effective in destructing the EDTA wastes than the cerium mediated oxidation process. For a constant volume of the EDTA wastes, the treatment time for the cerium-mediated oxidation was 9 hours and its conversion ratio of EDTA to water and CO 2 was 90.2 % at 80 deg. C, 10 A, but the treatment time for the silver-mediated oxidation was 3 hours and its conversion ratio was 89.2 % at 30 deg. C, 10 A. (authors)

  15. Electrochemical oxidation of selective estrogen receptor modulator raloxifene

    International Nuclear Information System (INIS)

    Li, Xi-Qian; He, Jian-Bo; Liu, Lu; Cui, Ting

    2013-01-01

    Highlights: ► Application and analysis of in situ thin-layer spectroelectrochemistry. ► Cyclic voltabsorptometry used for a drug study. ► Highly pH-dependent oxidative metabolism of raloxifene. ► A complex parallel-consecutive mechanism proposed for oxidation of raloxifene. -- Abstract: Raloxifene is a selective estrogen receptor modulator that may produce toxic oxidative species in metabolism. The oxidation mechanism of raloxifene with different pH values was studied by cyclic voltammetry, X-ray photoelectron spectroscopy (XPS), in situ UV–vis spectral analysis and cyclic voltabsorptometry based on a long optical-path thin-layer electrochemical cell. Time-derivative cyclic voltabsorptograms were obtained for comparative discussion with the corresponding cyclic voltammograms. Raloxifene was initially oxidized to reactive phenoxyl radicals, followed by a series of transformation steps leading to different final products in different pH media. A parallel-consecutive reaction mechanism was proposed for the pH-dependent formation of 7-hydroxyraloxifene, raloxifene 6,7-o-quinone and two raloxifene dimers, each pathway following a complex electrochemical-chemical mechanism. Both raloxifene diquinone methide and its N-oxides were not detected by in situ UV–vis spectroscopy and XPS analysis. This work provides an electrochemical viewpoint and comparable information for better understanding of the oxidative metabolism and chemical toxicology of raloxifene under physiological conditions in vivo or in vitro

  16. System and method to control h2o2 level in advanced oxidation processes

    DEFF Research Database (Denmark)

    2016-01-01

    The present invention relates to a bio-electrochemical system (BES) and a method of in-situ production and removal of H2O2 using such a bio-electrochemical system (BES). Further, the invention relates to a method for in-situ control of H2O2 content in an aqueous system of advanced oxidation...

  17. Advanced methods of solid oxide fuel cell modeling

    CERN Document Server

    Milewski, Jaroslaw; Santarelli, Massimo; Leone, Pierluigi

    2011-01-01

    Fuel cells are widely regarded as the future of the power and transportation industries. Intensive research in this area now requires new methods of fuel cell operation modeling and cell design. Typical mathematical models are based on the physical process description of fuel cells and require a detailed knowledge of the microscopic properties that govern both chemical and electrochemical reactions. ""Advanced Methods of Solid Oxide Fuel Cell Modeling"" proposes the alternative methodology of generalized artificial neural networks (ANN) solid oxide fuel cell (SOFC) modeling. ""Advanced Methods

  18. Electrochemical decontamination of waters by advanced oxidation

    African Journals Online (AJOL)

    a

    and are difficult to remove by classical and biological methods of wastewater and industrial .... C8H5Cl3O3 + 7 O2 → 8 CO2 + 3 HCl + H2O. (5) ..... Switzerland for preparing the boron-doped diamond electrodes, and the AECI, Spain Agency of.

  19. Electrochemical decontamination of waters by advanced oxidation ...

    African Journals Online (AJOL)

    Bulk electrolysis in the potential region of electrolyte decomposition leads to the complete destruction of 2,4,5-T and its degradation intermediates by means of the electrogeneration of the highly reactive hydroxyl radicals. The evolution of the chemical oxygen demand (COD) and the instant current efficiency (ICE) during the ...

  20. Electrochemical oxidation of niclosamide at a glassy carbon ...

    African Journals Online (AJOL)

    Cyclic voltammetry, square-wave voltammetry and controlled potential electrolysis have been used to study the electrochemical oxidation behaviour of niclosamide at a glassy carbon electrode. The number of electrons transferred, the wave characteristics, the diffusion coefficient and reversibility of the reactions have been ...

  1. Fractional surface termination of diamond by electrochemical oxidation.

    Science.gov (United States)

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

    2012-01-10

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

  2. Electrochemical activity of heavy metal oxides in the process of ...

    Indian Academy of Sciences (India)

    Unknown

    2002-02-02

    Feb 2, 2002 ... Electrochemical activity of heavy metal oxides in the process of chloride induced .... decrease of pH value by MeOx, a synergism of acidic and chloride ... inhibitors and their influence on the physical properties of. Portland ...

  3. Iron-Based Nanomaterials/Graphene Composites for Advanced Electrochemical Sensors

    Directory of Open Access Journals (Sweden)

    Kaveh Movlaee

    2017-11-01

    Full Text Available Iron oxide nanostructures (IONs in combination with graphene or its derivatives—e.g., graphene oxide and reduced graphene oxide—hold great promise toward engineering of efficient nanocomposites for enhancing the performance of advanced devices in many applicative fields. Due to the peculiar electrical and electrocatalytic properties displayed by composite structures in nanoscale dimensions, increasing efforts have been directed in recent years toward tailoring the properties of IONs-graphene based nanocomposites for developing more efficient electrochemical sensors. In the present feature paper, we first reviewed the various routes for synthesizing IONs-graphene nanostructures, highlighting advantages, disadvantages and the key synthesis parameters for each method. Then, a comprehensive discussion is presented in the case of application of IONs-graphene based composites in electrochemical sensors for the determination of various kinds of (biochemical substances.

  4. Iron-Based Nanomaterials/Graphene Composites for Advanced Electrochemical Sensors

    Science.gov (United States)

    Movlaee, Kaveh; Ganjali, Mohmmad Reza; Norouzi, Parviz

    2017-01-01

    Iron oxide nanostructures (IONs) in combination with graphene or its derivatives—e.g., graphene oxide and reduced graphene oxide—hold great promise toward engineering of efficient nanocomposites for enhancing the performance of advanced devices in many applicative fields. Due to the peculiar electrical and electrocatalytic properties displayed by composite structures in nanoscale dimensions, increasing efforts have been directed in recent years toward tailoring the properties of IONs-graphene based nanocomposites for developing more efficient electrochemical sensors. In the present feature paper, we first reviewed the various routes for synthesizing IONs-graphene nanostructures, highlighting advantages, disadvantages and the key synthesis parameters for each method. Then, a comprehensive discussion is presented in the case of application of IONs-graphene based composites in electrochemical sensors for the determination of various kinds of (bio)chemical substances. PMID:29168771

  5. Electrochemical reduction of actinides oxides in molten salts

    International Nuclear Information System (INIS)

    Claux, B.

    2011-01-01

    Reactive metals are currently produced from their oxide by multiple steps reduction techniques. A one step route from the oxide to the metal has been suggested for metallic titanium production by electrolysis in high temperature molten chloride salts. In the so-called FFC process, titanium oxide is electrochemically reduced at the cathode, generating O 2- ions, which are converted on a graphite anode into carbon oxide or dioxide. After this process, the spent salt can in principle be reused for several batches which is particularly attractive for a nuclear application in terms of waste minimization. In this work, the electrochemical reduction process of cerium oxide (IV) is studied in CaCl 2 and CaCl 2 -KCl melts to understand the oxide reduction mechanism. Cerium is used as a chemical analogue of actinides. Electrolysis on 10 grams of cerium oxide are made to find optimal conditions for the conversion of actinides oxides into metals. The scale-up to hundred grams of oxide is also discussed. (author) [fr

  6. Electrochemical preparation of new uranium oxide phases

    International Nuclear Information System (INIS)

    Smolenskij, V.V.; Lyalyushkin, N.V.; Bove, A.L.; Komarov, V.K.; Kapshukov, I.I.

    1992-01-01

    Behaviour of uranium ions in oxidation states 3+ and 4+ in molten chlorides of alkali metals in the temperature range of 700-900 degC in the atmosphere of an inert gas was studied by the method of cyclic voltametry. It is shown that as a result of introduction of crystal uranium dioxide into the salt melt formation of uranium oxide ions of the composition UO + and UO 2+ occurs, the ions participating in electrode reactions and bringing about formation of the following uranium oxides on the cathode: UO and, presumably, U 3 O 4 . Oxides UO and U 3 O 4 are thermodynamically unstable at low temperatures and decompose into uranium oxide of the composition UO 2-x , where x varies from 0 to 0.05, and metal uranium

  7. Electrochemical Oxidation by Square-Wave Potential Pulses in the Imitation of Oxidative Drug Metabolism

    NARCIS (Netherlands)

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

    2011-01-01

    Electrochemistry combined with mass spectrometry (EC-MS) is an emerging analytical technique in the imitation of oxidative drug metabolism at the early stages of new drug development. Here, we present the benefits of electrochemical oxidation by square-wave potential pulses for the oxidation of

  8. Zinc oxide nanostructures for electrochemical cortisol biosensing

    Science.gov (United States)

    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 KΩ. M-1 for ZnO-NRs and 540 Ω. 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.

  9. Increased electrochemical properties of ruthenium oxide and graphene/ruthenium oxide hybrid dispersed by polyvinylpyrrolidone

    International Nuclear Information System (INIS)

    Chen, Yao; Zhang, Xiong; Zhang, Dacheng; Ma, Yanwei

    2012-01-01

    Highlights: ► A good dispersion of RuO 2 and graphene/RuO 2 is obtained by polyvinylpyrrolidone. ► PVP as a dispersant also can prevent the formation of metal Ru in graphene/RuO 2 . ► The max capacitances of the hybrid and RuO 2 reach 435 and 597 F g −1 at 0.2 A g −1 . ► The hybrid shows the best rate capability of 39% at 50 A g −1 . - Abstract: Ruthenium oxide has been prepared by a sol–gel method. Polyvinylpyrrolidone (PVP) as an excellent polymeric dispersant is adopted to prevent aggregation of ruthenium oxide. In order to enhance the rate capability of ruthenium oxide, graphene with residual oxygen functional groups as a 2D support has been merged into ruthenium oxide. These oxygen functional groups not only favor to form stable few layers of graphene colloids, but also offer the sites to anchor ruthenium oxide nanoparticles. X-ray diffraction infers that PVP can also hinder the partial formation of Ru by blocking the direct contact between the Ru 3+ and the graphene in the sol–gel synthesis of the hybrids. The ruthenium oxide and the graphene/ruthenium oxide hybrids dispersed by PVP have superior electrochemical properties due to good dispersing and protecting ability of PVP. Especially, the hybrids using PVP exhibit the best rate capability, indicating that the composites possess an advanced structure of combining sheets and particles in nano-scale.

  10. Manganese oxide-based materials as electrochemical supercapacitor electrodes.

    Science.gov (United States)

    Wei, Weifeng; Cui, Xinwei; Chen, Weixing; Ivey, Douglas G

    2011-03-01

    Electrochemical supercapacitors (ECs), characteristic of high power and reasonably high energy densities, have become a versatile solution to various emerging energy applications. This critical review describes some materials science aspects on manganese oxide-based materials for these applications, primarily including the strategic design and fabrication of these electrode materials. Nanostructurization, chemical modification and incorporation with high surface area, conductive nanoarchitectures are the three major strategies in the development of high-performance manganese oxide-based electrodes for EC applications. Numerous works reviewed herein have shown enhanced electrochemical performance in the manganese oxide-based electrode materials. However, many fundamental questions remain unanswered, particularly with respect to characterization and understanding of electron transfer and atomic transport of the electrochemical interface processes within the manganese oxide-based electrodes. In order to fully exploit the potential of manganese oxide-based electrode materials, an unambiguous appreciation of these basic questions and optimization of synthesis parameters and material properties are critical for the further development of EC devices (233 references).

  11. Electrochemical investigations of ion-implanted oxide films

    International Nuclear Information System (INIS)

    Schultze, J.W.; Danzfuss, B.; Meyer, O.; Stimming, U.

    1985-01-01

    Oxide films (passive films) of 40-50 nm thickness were prepared by anodic polarization of hafnium and titanium electrodes up to 20 V. Multiple-energy ion implantation of palladium, iron and xenon was used in order to obtain modified films with constant concentration profiles of the implanted ions. Rutherford backscattering, X-ray photoelectron spectroscopy measurements and electrochemical charging curves prove the presence of implanted ions, but electrochemical and photoelectrochemical measurements indicate that the dominating effect of ion implantation is the disordering of the oxide film. The capacity of hafnium electrodes increases as a result of an increase in the dielectric constant D. For titanium the Schottky-Mott analysis shows that ion implantation causes an increase in D and the donor concentration N. Additional electronic states in the band gap which are created by the implantation improve the conductivity of the semiconducting or insulating films. This is seen in the enhancement of electron transfer reactions and its disappearance during repassivation and annealing. Energy changes in the band gap are derived from photoelectrochemical measurements; the absorption edge of hafnium oxide films decreases by approximately 2 eV because of ion implantation, but it stays almost constant for titanium oxide films. All changes in electrochemical behavior caused by ion implantation show little variation with the nature of the implanted ion. Hence the dominating effect seems to be a disordering of the oxide. (Auth.)

  12. Progress in electrochemical synthesis of magnetic iron oxide nanoparticles

    International Nuclear Information System (INIS)

    Ramimoghadam, Donya; Bagheri, Samira; Hamid, Sharifah Bee Abd

    2014-01-01

    Recently, magnetic iron oxide particles have been emerged as significant nanomaterials due to its extensive range of application in various fields. In this regard, synthesis of iron oxide nanoparticles with desirable properties and high potential applications are greatly demanded. Therefore, investigation on different iron oxide phases and their magnetic properties along with various commonly used synthetic techniques are remarked and thoroughly described in this review. Electrochemical synthesis as a newfound method with unique advantages is elaborated, followed by design approaches and key parameters to control the properties of the iron oxide nanoparticles. Additionally, since the dispersion of iron oxide nanoparticles is as important as its preparation, surface modification issue has been a serious challenge which is comprehensively discussed using different surfactants. Despite the advantages of the electrochemical synthesis method, this technique has been poorly studied and requires deep investigations on effectual parameters such as current density, pH, electrolyte concentration etc. - Highlights: • IONPs are applied in chemical industries, medicine, magnetic storage etc. • Electrochemical synthesis (EC) is convenient, eco-friendly, selective and low-cost. • EC key factors are current density, pH, electrolyte concentration, electrode type. • Organic, inorganic and biological materials can be used to modify IONPs’ surface. • The physicochemical properties of IONPs can be controlled by adding surfactants

  13. Electrochemical Multi-Coloration of Molybdenum Oxide Bronzes

    International Nuclear Information System (INIS)

    Lee, Sangmin; Saji, Viswanathan S.; Lee, Chiwoo

    2013-01-01

    We report a simple electrochemical approach in fabricating multiple colored molybdenum (Mo) oxide bronzes on the surface of a Mo-quartz electrode. A three step electrochemical batch process consisting of linear sweep voltammetry and anodic oxidation followed by cathodic reduction in neutral K 2 SO 4 electrolyte at different end potentials, viz. -0.62, -0.80 and -1.60 V (vs. Hg/HgSO 4 ) yielded red, blue and yellow colored bronzes. The samples produced were analyzed by XRD, EDS, and SIMS. The color variation was suggested to be associated with the cations intercalation into the oxide formed and the simultaneous structural changes that occurred during the cathodic reduction in neutral aqueous medium

  14. Electrochemical Multi-Coloration of Molybdenum Oxide Bronzes

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sangmin; Saji, Viswanathan S.; Lee, Chiwoo [Korea Univ., Seoul (Korea, Republic of)

    2013-08-15

    We report a simple electrochemical approach in fabricating multiple colored molybdenum (Mo) oxide bronzes on the surface of a Mo-quartz electrode. A three step electrochemical batch process consisting of linear sweep voltammetry and anodic oxidation followed by cathodic reduction in neutral K{sub 2}SO{sub 4} electrolyte at different end potentials, viz. -0.62, -0.80 and -1.60 V (vs. Hg/HgSO{sub 4}) yielded red, blue and yellow colored bronzes. The samples produced were analyzed by XRD, EDS, and SIMS. The color variation was suggested to be associated with the cations intercalation into the oxide formed and the simultaneous structural changes that occurred during the cathodic reduction in neutral aqueous medium.

  15. Solar-mediated thermo-electrochemical oxidation of sodium dodecyl benzene sulfonate by modulating the effective oxidation potential and pathway for green remediation of wastewater

    Science.gov (United States)

    Gu, Di; Gao, Simeng; Jiang, TingTing; Wang, Baohui

    2017-01-01

    To match the relentless pursuit of three research hot points - efficient solar utilization, green and sustainable remediation of wastewater and advanced oxidation processes, solar-mediated thermo-electrochemical oxidation of surfactant was proposed and developed for green remediation of surfactant wastewater. The solar thermal electrochemical process (STEP), fully driven with solar energy to electric energy and heat and without an input of other energy, sustainably serves as efficient thermo-electrochemical oxidation of surfactant, exemplified by SDBS, in wastewater with the synergistic production of hydrogen. The electrooxidation-resistant surfactant is thermo-electrochemically oxidized to CO2 while hydrogen gas is generated by lowing effective oxidation potential and suppressing the oxidation activation energy originated from the combination of thermochemical and electrochemical effect. A clear conclusion on the mechanism of SDBS degradation can be proposed and discussed based on the theoretical analysis of electrochemical potential by quantum chemical method and experimental analysis of the CV, TG, GC, FT-IR, UV-vis, Fluorescence spectra and TOC. The degradation data provide a pilot for the treatment of SDBS wastewater that appears to occur via desulfonation followed by aromatic-ring opening. The solar thermal utilization that can initiate the desulfonation and activation of SDBS becomes one key step in the degradation process. PMID:28294180

  16. Selective Electrochemical Generation of Hydrogen Peroxide from Water Oxidation

    DEFF Research Database (Denmark)

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

    2015-01-01

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

  17. Distributed electrochemical sensors: recent advances and barriers to market adoption.

    Science.gov (United States)

    Hoekstra, Rafael; Blondeau, Pascal; Andrade, Francisco J

    2018-07-01

    Despite predictions of their widespread application in healthcare and environmental monitoring, electrochemical sensors are yet to be distributed at scale, instead remaining largely confined to R&D labs. This contrasts sharply with the situation for physical sensors, which are now ubiquitous and seamlessly embedded in the mature ecosystem provided by electronics and connectivity protocols. Although chemical sensors could be integrated into the same ecosystem, there are fundamental issues with these sensors in the three key areas of analytical performance, usability, and affordability. Nevertheless, advances are being made in each of these fields, leading to hope that the deployment of automated and user-friendly low-cost electrochemical sensors is on the horizon. Here, we present a brief survey of key challenges and advances in the development of distributed electrochemical sensors for liquid samples, geared towards applications in healthcare and wellbeing, environmental monitoring, and homeland security. As will be seen, in many cases the analytical performance of the sensor is acceptable; it is usability that is the major barrier to commercial viability at this moment. Were this to be overcome, the issue of affordability could be addressed. Graphical Abstract ᅟ.

  18. Recent Advances in Porous Carbon Materials for Electrochemical Energy Storage.

    Science.gov (United States)

    Wang, Libin; Hu, Xianluo

    2018-06-18

    Climate change and the energy crisis have promoted the rapid development of electrochemical energy-storage devices. Owing to many intriguing physicochemical properties, such as excellent chemical stability, high electronic conductivity, and a large specific surface area, porous carbon materials have always been considering as a promising candidate for electrochemical energy storage. To date, a wide variety of porous carbon materials based upon molecular design, pore control, and compositional tailoring have been proposed for energy-storage applications. This focus review summarizes recent advances in the synthesis of various porous carbon materials from the view of energy storage, particularly in the past three years. Their applications in representative electrochemical energy-storage devices, such as lithium-ion batteries, supercapacitors, and lithium-ion hybrid capacitors, are discussed in this review, with a look forward to offer some inspiration and guidelines for the exploitation of advanced carbon-based energy-storage materials. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Treatment of aqueous wastes contaminated with Congo Red dye by electrochemical oxidation and ozonation processes

    International Nuclear Information System (INIS)

    Faouzi Elahmadi, Mohammed; Bensalah, Nasr; Gadri, Abdellatif

    2009-01-01

    Synthetic aqueous wastes polluted with Congo Red (CR) have been treated by two advanced oxidation processes: electrochemical oxidation on boron doped diamond anodes (BDD-EO) and ozonation under alkaline conditions. For same concentrations, galvanostatic electrolyses have led to total COD and TOC removals but ozonation process can reach only 85% and 81% of COD and TOC removals, respectively. UV-vis qualitative analyses have shown different behaviors of CR molecules towards ozonation and electrochemical oxidation. Rapid discoloration has been observed during ozonation, whereas color persistence till the end of galvanostatic electrolyses has been seen during BDD-EO process. It seems that the oxidation mechanisms involved in the two processes are different: simultaneous destruction of azoic groups is suggested during ozonation process but consecutive destruction of these groups is proposed during BDD-EO. However, energetic study has evidenced that BDD-EO appears more efficient and more economic than ozonation in terms of TOC removals. These results have been explained by the fact that during BDD-EO, other strong oxidants electrogenerated from the electrolyte oxidation such as persulfates and direct-oxidation of CR and its byproducts on BDD anodes complement the hydroxyl radicals mediated oxidation to accomplish the total mineralization of organics.

  20. Preparation of the electrochemically formed spinel-lithium manganese oxides

    Energy Technology Data Exchange (ETDEWEB)

    Katakura, Katsumi; Wada, Kohei; Kajiki, Yoshiyuki; Yamamoto, Akiko [Department of Chemical Engineering, Nara National College of Technology, 22 Yata-cho Yamotokoriyama, Nara 639-1080 (Japan); Ogumi, Zempachi [Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto 615-8510 (Japan)

    2009-04-01

    Electrochemically formed spinel-lithium manganese oxides were synthesized from manganese hydroxides prepared by a cathodic electrochemical precipitation from various concentrations of manganese nitrate solutions. Two types of manganese hydroxides were formed from diluted and concentrated Mn(NO{sub 3}){sub 2} aqueous solutions. Uniform and equi-sized disk shaped Mn(OH){sub 2} crystals of 0.2-5 {mu}m in diameter were obtained on a Pt substrate after the electrochemical precipitation from lower concentration of ranging from 2 mmol dm{sup -3} to 2 mol dm{sup -3} Mn(NO{sub 3}){sub 2} aq., while the grass blade-like precipitate which is ascribed to manganese hydroxide with 20-80 {mu}m long and 1-5 {mu}m wide were formed from concentrated Mn(NO{sub 3}){sub 2} aq. Both manganese hydroxides gave the electrochemically formed spinel-LiMn{sub 2}O{sub 4} onto a Pt sheet, which is ready for electrochemical measurement, after calcination of the Li incorporated precipitate at 750 C without any additives. While the shape and size of the secondary particle frameworks (aggregates) of the electrochemically formed spinel-LiMn{sub 2}O{sub 4} can be controlled by the electrolysis conditions, the nanostructured primary crystals of 200 nm in diameter were obtained in all cases except that the fiber-like nanostructured spinel-LiMn{sub 2}O{sub 4} crystals with 200 nm in diameter were obtained from concentrated Mn(NO{sub 3}){sub 2} aq. Though these two types of electrochemically formed spinel-LiMn{sub 2}O{sub 4} showed well-shaped CVs even in higher scan rates, it would be suitable for high power density battery applications. These behaviors are assumed to be ascribed to the crystal size and shape of the processed spinel-LiMn{sub 2}O{sub 4}. (author)

  1. Electrochemical studies on vanadium oxides, 9

    International Nuclear Information System (INIS)

    Miura, Takashi; Yamamoto, Masahiro; Takahashi, Hirobumi; Kishi, Tomiya; Nagai, Takashi

    1979-01-01

    The mechanism of the anodic oxidation of various organic compounds-including methanol, formaldehyde, formic acid, ethanol, acetaldehyde and acetic acid-at illuminated vanadium pentoxide (V 2 O 5 ) single crystal electrodes were investigated in aqueous solutions of an H 2 SO 4 -K 2 SO 4 system of about pH 2, in which oxygen evolution from water molecules had previously been confirmed to occur with a current efficiency of about 100%. It was shown that all the organics were oxidized by the so called hole-current doubling mechanism, and that the oxygen evolution reaction, which competed with the above oxidation reaction at the hole-capturing step from the valence band of the electrode, proceeded by the simple hole-capturing mechanism, not followed by an electron injection step into the conduction band. Furthermore, it is considered that chloride ions added to the electrolytes tended to hinder hole-current doubling oxidation owing to their reactivity with the holes at the illuminated V 2 O 5 electrodes. (author)

  2. Electrochemical synthesis and characterization of copper (I oxide

    Directory of Open Access Journals (Sweden)

    Bugarinović Sanja J.

    2009-01-01

    Full Text Available The quest and need for clean and economical energy sources have increased interest in the development of thin film cells technologies. Electrochemical deposition is an attractive method for synthesis of thin films. It offers the advantages of low synthesis temperature, low cost and high purity. Copper (I oxide or cuprous oxide is an oxide semiconductor which is used as the anodic material in the form of thin film in lithium batteries and solar cells. The cathodic process of synthesis of cuprous oxide thin film is carried out in a potentiostatic mode from the organic electrolyte. The process parameters are chosen in that way to accomplish maximum difference between the potentials at which Cu2O and CuO are obtained. The electrochemical characterization was carried out by cyclic voltammetry. The electrodeposition techniques are particularly well suited for the deposition of single elements but it is also possible to carry out simultaneous depositions of several elements and syntheses of well-defined alternating layers of metals and oxides with thicknesses down to a few nm. Nanomaterials exhibit novel physical properties and play an important role in fundamental research. In addition, cuprous oxide is commonly used as a pigment, a fungicide, and an antifouling agent for marine paints. It is insoluble in water and organic solvents. This work presents the examinations of the influence of bath, temperature, pH and current density on the characteristics of electrochemically synthesized cuprous oxide. In the 'classic' process of synthesis, which is carried out under galvanostatic conditions on the anode, the grain size of the powder decreases with the increase in current density while the grain colour becomes lighter. The best commercial quality of the Cu2O (grain size, colour, content of choride was obtained at the temperature of 80°C, concentration of NaCl of 3 mol/dm3 and current density of 400 A/m2.

  3. Nitrogen-doped reduced graphene oxide electrodes for electrochemical supercapacitors.

    Science.gov (United States)

    Nolan, Hugo; Mendoza-Sanchez, Beatriz; Ashok Kumar, Nanjundan; McEvoy, Niall; O'Brien, Sean; Nicolosi, Valeria; Duesberg, Georg S

    2014-02-14

    Herein we use Nitrogen-doped reduced Graphene Oxide (N-rGO) as the active material in supercapacitor electrodes. Building on a previous work detailing the synthesis of this material, electrodes were fabricated via spray-deposition of aqueous dispersions and the electrochemical charge storage mechanism was investigated. Results indicate that the functionalised graphene displays improved performance compared to non-functionalised graphene. The simplicity of fabrication suggests ease of up-scaling of such electrodes for commercial applications.

  4. Sol-gel Technology and Advanced Electrochemical Energy Storage Materials

    Science.gov (United States)

    Chu, Chung-tse; Zheng, Haixing

    1996-01-01

    Advanced materials play an important role in the development of electrochemical energy devices such as batteries, fuel cells, and electrochemical capacitors. The sol-gel process is a versatile solution for use in the fabrication of ceramic materials with tailored stoichiometry, microstructure, and properties. This processing technique is particularly useful in producing porous materials with high surface area and low density, two of the most desirable characteristics for electrode materials. In addition,the porous surface of gels can be modified chemically to create tailored surface properties, and inorganic/organic micro-composites can be prepared for improved material performance device fabrication. Applications of several sol-gel derived electrode materials in different energy storage devices are illustrated in this paper. V2O5 gels are shown to be a promising cathode material for solid state lithium batteries. Carbon aerogels, amorphous RuO2 gels and sol-gel derived hafnium compounds have been studied as electrode materials for high energy density and high power density electrochemical capacitors.

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

    Science.gov (United States)

    Isenberg, Arnold O.

    1987-01-01

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

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

    NARCIS (Netherlands)

    Song, Jing; Hempenius, Mark A.; Chung, H.J.; Vancso, Gyula J.

    2015-01-01

    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

  7. Electrochemical Oxidation of PAHs in Water from Harbor Sediment Purification

    DEFF Research Database (Denmark)

    Muff, Jens; Søgaard, Erik Gydesen

    2010-01-01

    generated oxidant solution with a free chlorine concentration of 2 gL-1. Both strategies resulted in a successful degradation of 5 PAHs to fulfil the discharge limit on 0.010 µgL-1. The intermixing-with-oxidant approach can also be applied as a method to address the actual sediment matrix....... of the discharge water addressing primarily polycyclic aromatic hydrocarbons (PAHs). PAHs are by-products of incomplete combustion of organic materials with recalcitrant and strong mutagenic/carcinogenic properties, due to their benzene analogue structures. PAHs are hydrophobic compounds and their persistence...... evidence for the importance of the indirect oxidation mechanism in the degradation of the PAHs. The proof-of-concept study was conducted both by a direct treatment approach and an intermixing-with-oxidant approach, where the contaminated water was intermixed in different ratios with an electrochemically...

  8. HANDBOOK ON ADVANCED PHOTOCHEMICAL OXIDATION ...

    Science.gov (United States)

    This handbook summarizes commercial-scale system performance and cost data for advanced photochemical oxidation (APO) treatment of contaminated water, air, and solids. Similar information from pilot- and bench-scale evaluations of APO processes is also included to supplement the commercial-scale data. Performance and cost data is summarized for various APO processes, including vacuum ultraviolet (VUV) photolysis, ultraviolet (UV)/oxidation, photo-Fenton, and dye- or semiconductor-sensitized APO processes. This handbook is intended to assist engineering practitioners in evaluating the applicability of APO processes and in selecting one or more such processes for site-specific evaluation.APO has been shown to be effective in treating contaminated water and air. Regarding contaminated water treatment, UV/oxidation has been evaluated for the most contaminants, while VUV photolysis has been evaluated for the fewest. Regarding contaminated air treatment, the sensitized APO processes have been evaluated for the most contaminants, while VUV photolysis has been evaluated for the fewest.APO processes for treating contaminated solids generally involve treatment of contaminated slurry or leachate generated using an extraction process such as soil washing. APO has been shown to be effective in treating contaminated solids, primarily at the bench-scale level. Information

  9. Mechanisms of electrochemical reduction and oxidation of nitric oxide

    NARCIS (Netherlands)

    Vooys, de A.C.A.; Beltramo, G.L.; Riet, van B.; Veen, van J.A.R.; Koper, M.T.M.

    2004-01-01

    A summary is given of recent work on the reactivity of nitric oxide on various metal electrodes. The significant differences between the reactivity of adsorbed NO and NO in solution are pointed out, both for the reduction and the oxidation reaction(s). Whereas adsorbed NO can be reduced only to

  10. Surface Characterization and Electrochemical Oxidation of Metal Doped Uranium Dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeongmook; Kim, Jandee; Youn, Young-Sang; Kim, Jong-Goo; Ha, Yeong-Keong; Kim, Jong-Yun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    Trivalent element in UO{sub 2} matrix makes the oxygen vacancy from loss of oxygen for charge compensation. Tetravalent element alters lattice parameter of UO{sub 2} due to diameter difference between the tetravalent element and replaced U. These structural changes have significant effect on not only relevant fuel performance but also the kinetics of fuel oxidation. Park and Olander explained the stabilization of Ln (III)-doped UO{sub 2} against oxidation based on oxygen potential calculations. In this work, we have been investigated the effect of Gd{sup 3+} and Th{sup 4+} doping on the UO{sub 2} structure with Raman spectroscopy and X-ray diffraction to characterize the surface structure of nuclear fuel material. For Gd doped UO{sub 2}, its electrochemical oxidation behaviors are also investigated. The Gd and Th doped uranium dioxide solid solution pellets with various doping level were investigated by XRD, Raman spectroscopy, SEM, electrochemical experiments to investigate surface structure and electro chemical oxidation behaviors. The lattice parameter evaluated from XRD spectra indicated the formation of solid solutions. Raman spectra showed the existence of the oxygen vacancy. SEM images showed the grain structure on the surface of Gd doped uranium dioxide depending on doping level and oxygen-to-metal ratio.

  11. Comparative DEMS study on the electrochemical oxidation of carbon blacks

    DEFF Research Database (Denmark)

    Ashton, Sean James; Arenz, Matthias

    2012-01-01

    Publication year: 2012 Source:Journal of Power Sources, Volume 217 Sean J. Ashton, Matthias Arenz The intention of the study presented here is to compare the electrochemical oxidation tendencies of a pristine Ketjen Black EC300 high surface area (HSA) carbon black, and four graphitised counterparts...... heat-treated between 2100 and 3200 °C, such as those typically used as corrosion resistant carbon (CRC) supports for polymer electrolyte membrane fuel cell (PEMFC) catalysts. A methodology combining cyclic voltammetry (CV) and differential electrochemical mass spectrometry (DEMS) is used, which allows......; however, CRC samples graphitised =2800 °C did not exhibit this same behaviour. Highlights ¿ We quantitatively determine electrooxidation of carbon support materials. ¿ We can distinguish between the total and partial electrooxidation. ¿ Non or mildly heat treated carbon forms passivating layer. ¿ Heat...

  12. Advanced Oxidation Degradation of Diclofenac

    Energy Technology Data Exchange (ETDEWEB)

    Cooper, William J., E-mail: wcooper@uci.edu [Urban Water Research Center, Department of Civil and Environmental Engineering, University of California, Irvine, CA 92697 (United States); Song Weihua, E-mail: wsong@fudan.edu.cn [Department of Environmental Science & Engineering, Fudan University, Shanghai 200433 (China)

    2012-07-01

    Advanced oxidation/reduction processes (AO/RPs), utilize free radical reactions to directly degrade chemical contaminants as an alternative to traditional water treatment. This study reports the absolute rate constants for reaction of diclofenac sodium and the model compound (2, 6-dichloraniline) with the two major AO/RP radicals; the hydroxyl radical (•OH) and hydrated electron (e{sup -}{sub aq}). The bimolecular reaction rate constants (M{sup -1} s{sup -1}) for diclofenac for •OH was (9.29 ± 0.11) x 10{sup 9}, and, for e- aq was (1.53 ± 0.03) x10{sup 9}. Preliminary degradation mechanisms are suggested based on product analysis using {sup 60}Co γ-irradiation and LC-MS for reaction by-product identification. The toxicity of products was evaluated using the Vibrio fischeri luminescent bacteria method. (author)

  13. Advanced Oxidation Degradation of Diclofenac

    International Nuclear Information System (INIS)

    Cooper, William J.; Song Weihua

    2012-01-01

    Advanced oxidation/reduction processes (AO/RPs), utilize free radical reactions to directly degrade chemical contaminants as an alternative to traditional water treatment. This study reports the absolute rate constants for reaction of diclofenac sodium and the model compound (2, 6-dichloraniline) with the two major AO/RP radicals; the hydroxyl radical (•OH) and hydrated electron (e - aq ). The bimolecular reaction rate constants (M -1 s -1 ) for diclofenac for •OH was (9.29 ± 0.11) x 10 9 , and, for e- aq was (1.53 ± 0.03) x10 9 . Preliminary degradation mechanisms are suggested based on product analysis using 60 Co γ-irradiation and LC-MS for reaction by-product identification. The toxicity of products was evaluated using the Vibrio fischeri luminescent bacteria method. (author)

  14. AN ADVANCED OXIDATION PROCESS : FENTON PROCESS

    Directory of Open Access Journals (Sweden)

    Engin GÜRTEKİN

    2008-03-01

    Full Text Available Biological wastewater treatment is not effective treatment method if raw wastewater contains toxic and refractory organics. Advanced oxidation processes are applied before or after biological treatment for the detoxification and reclamation of this kind of wastewaters. The advanced oxidation processes are based on the formation of powerful hydroxyl radicals. Among advanced oxidation processes Fenton process is one of the most promising methods. Because application of Fenton process is simple and cost effective and also reaction occurs in a short time period. Fenton process is applied for many different proposes. In this study, Fenton process was evaluated as an advanced oxidation process in wastewater treatment.

  15. Mechanism of glucose electrochemical oxidation on gold surface

    KAUST Repository

    Pasta, Mauro; La Mantia, Fabio; Cui, Yi

    2010-01-01

    The complex oxidation of glucose at the surface of gold electrodes was studied in detail in different conditions of pH, buffer and halide concentration. As observed in previous studies, an oxidative current peak occurs during the cathodic sweep showing a highly linear dependence on glucose concentration, when other electrolyte conditions are unchanged. The effect of the different conditions on the intensity of this peak has stressed the limitations of the previously proposed mechanisms. A mechanism able to explain the presence of this oxidative peak was proposed. The mechanism takes into account ion-sorption and electrochemical adsorption of OH-, buffer species (K2HPO4/KH2PO4) and halides. © 2010 Elsevier Ltd. All rights reserved.

  16. Electrochemical oxidation of methanol on Pt3Co bulk alloy

    Directory of Open Access Journals (Sweden)

    S. LJ. GOJKOVIC

    2003-11-01

    Full Text Available The electrochemical oxidation of methanol was investigated on a Pt3Co bulk alloy in acid solutions. Kinetic parameters such as transfer coefficient, reaction orders with respect to methanol and H+ ions and energy of activation were determined. It was found that the rate of methanol oxidation is significantly diminished by rotation of the electrode. This effect was attributed to the diffusion of formaldehyde and formic acid from the electrode surface. Stirring of the electrolyte also influenced the kinetic parameters of the reaction. It was speculated that the predominant reaction pathway and rate determining step are different in the quiescent and in the stirred electrolyte. Cobalt did not show a promoting effect on the rate of methanol oxidation on the Pt3Co bulk alloy with respect to a pure Pt surface.

  17. Mechanism of glucose electrochemical oxidation on gold surface

    KAUST Repository

    Pasta, Mauro

    2010-08-01

    The complex oxidation of glucose at the surface of gold electrodes was studied in detail in different conditions of pH, buffer and halide concentration. As observed in previous studies, an oxidative current peak occurs during the cathodic sweep showing a highly linear dependence on glucose concentration, when other electrolyte conditions are unchanged. The effect of the different conditions on the intensity of this peak has stressed the limitations of the previously proposed mechanisms. A mechanism able to explain the presence of this oxidative peak was proposed. The mechanism takes into account ion-sorption and electrochemical adsorption of OH-, buffer species (K2HPO4/KH2PO4) and halides. © 2010 Elsevier Ltd. All rights reserved.

  18. Feasibility of electrochemical oxidation process for treatment of saline wastewater

    Directory of Open Access Journals (Sweden)

    Kavoos Dindarloo

    2015-09-01

    Full Text Available Background: High concentration of salt makes biological treatment impossible due to bacterial plasmolysis. The present research studies the process of electrochemical oxidation efficiency and optimal levels as important factors affecting pH, salt concentration, reaction time and applied voltage. Methods: The sample included graphite electrodes with specifications of 2.5 cm diameter and 15 cm height using a reactor with an optimum capacity of 1 L. Sixty samples were obtained with the aid of the experiments carried out in triplicates for each factor at 5 different levels. The entire experiments were performed based on standard methods for water and waste water treatments. Results: Analysis of variance carried out on effect of pH, salt concentration, reaction time and flow intensity in elimination of chemical oxygen demand (COD showed that they are significant factors affecting this process and reduce COD with a coefficient interval of 95% and test power of 80%. Scheffe test showed that at optimal level, a reaction time of 1 hour, 10 g/L concentration, pH = 9 and 15 V electrical potential difference were obtained. Conclusion: Waste waters containing salt may contribute to the electro-oxidation process due to its cations and anions. Therefore, the process of electrochemical oxidation with graphite electrodes could be a proper strategy for the treatment of saline wastewater where biological treatment is not possible.

  19. Manganese oxide/graphene oxide composites for high-energyaqueous asymmetric electrochemical capacitors

    CSIR Research Space (South Africa)

    Jafta, CJ

    2013-11-01

    Full Text Available A high-energy aqueous asymmetric electrochemical capacitor was developed using manganese diox-ide ( -MnO2)/graphene oxide (GO) nanocomposites. The nanostructured -MnO2was prepared frommicron-sized commercial electrolytic manganese dioxide (EMD) via...

  20. Two-Step Electrochemical Intercalation and Oxidation of Graphite for the Mass Production of Graphene Oxide.

    Science.gov (United States)

    Cao, Jianyun; He, Pei; Mohammed, Mahdi A; Zhao, Xin; Young, Robert J; Derby, Brian; Kinloch, Ian A; Dryfe, Robert A W

    2017-12-06

    Conventional chemical oxidation routes for the production of graphene oxide (GO), such as the Hummers' method, suffer from environmental and safety issues due to their use of hazardous and explosive chemicals. These issues are addressed by electrochemical oxidation methods, but such approaches typically have a low yield due to inhomogeneous oxidation. Herein we report a two-step electrochemical intercalation and oxidation approach to produce GO on the large laboratory scale (tens of grams) comprising (1) forming a stage 1 graphite intercalation compound (GIC) in concentrated sulfuric acid and (2) oxidizing and exfoliating the stage 1 GIC in an aqueous solution of 0.1 M ammonium sulfate. This two-step approach leads to GO with a high yield (>70 wt %), good quality (>90%, monolayer), and reasonable oxygen content (17.7 at. %). Moreover, the as-produced GO can be subsequently deeply reduced (3.2 at. % oxygen; C/O ratio 30.2) to yield highly conductive (54 600 S m -1 ) reduced GO. Electrochemical capacitors based on the reduced GO showed an ultrahigh rate capability of up to 10 V s -1 due to this high conductivity.

  1. Electrochemical Oxidation of Cyanide Using Platinized Ti Electrodes

    Directory of Open Access Journals (Sweden)

    Aušra VALIŪNIENĖ

    2013-12-01

    Full Text Available The cyanide-containing effluents are dangerous ecological hazards and must be treated before discharging into the environment. Anodic oxidation is one of the best ways to degrade cyanides. Pt anodes as the most efficient material for the cyanide electrochemical degradation are widely used. However, these electrodes are too expensive for industrial purposes. In this work Ti electrodes covered with nano-sized Pt particle layer were prepared and used for the anodic oxidation of cyanide ions. Surface images of Ti electrodes and Ti electrodes covered with different thickness layer of Pt were compared and characterized by the atomic force microscopy (AFM. The products formed in the solution during the CN- ions electrooxidation were examined by the Raman spectroscopy. An electrochemical Fast Fourier transformation (FFT impedance spectroscopy was used to estimate the parameters that reflect real surface roughness of Pt-modified Ti electrodes.DOI: http://dx.doi.org/10.5755/j01.ms.19.4.2514

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

    International Nuclear Information System (INIS)

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

    1991-01-01

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

  3. MECHANISTIC STUDY OF COLCHICINE’s ELECTROCHEMICAL OXIDATION

    International Nuclear Information System (INIS)

    Bodoki, Ede; Chira, Ruxandra; Zaharia, Valentin; Săndulescu, Robert

    2015-01-01

    Colchicine, as one of the most ancient drugs of human kind, is still in the focal point of the current research due to its multimodal mechanism of action. The elucidation of colchicine’s still unknown redox properties may play an important role in deciphering its beneficial and harmful implications over the human body. Therefore, a systematic mechanistic study of colchicine’s oxidation has been undertaken by electrochemistry coupled to mass spectrometry using two different types of electrolytic cells, in order to clarify the existing inconsistencies with respect to this topic. At around 1 V vs. Pd/H 2 , initiated by a one-electron transfer, the oxidation of colchicine sets off leading to a cation radical, whose further oxidation may evolve on several different pathways. The main product of the anodic electrochemical reaction, regardless of the carrier solution’s pH is represented by a 7-hydroxy derivative of colchicine. At more anodic potentials (above 1.4 V vs. Pd/H 2 ) compounds arising from epoxidation and/or multiple hydroxylation occur. No di- or tridemethylated quinone structures, as previously suggested in the literature for the electrolytic oxidation of colchicine, has been detected in the mass spectra.

  4. Metallic oxide reduction in molten chlorides: electrochemical solvent regeneration

    International Nuclear Information System (INIS)

    Martin, A.

    2005-11-01

    We consider the reaction MeO 2 + 2 Ca → Me + 2 CaO in CaCl 2 at 850 C. We want to re-use the molten media, which is a CaO-CaCl 2 melt at the end of the reaction. For that we want to de-oxidize it. When we electrolyse CaO we obtain Ca and O 2 ; it presents three difficult points that we want to solve: (1) it is difficult to oxidize O 2 - without oxidizing Cl - because their oxidation potential are very closed, (2) the chemical or electrochemical anodic corrosion, (3) the anodically produced gas dissolution in the mell One way of avoiding chlorine gas evolution is to prevent chloride ions from reaching the anode, for example using a selective membrane. Furthermore, the best prevention of the anodically produced gas dissolution in the melt can be done with a compartment, physically separating the anode from the rest of the reactional media. Thus in this work we have used an yttria stabilized zirconia membrane as a selective membrane for the deoxidation of a CaO-CaCl 2 melt at 850 C. (author)

  5. Electrochemical oxidation of phenol in a parallel plate reactor using ruthenium mixed metal oxide electrode

    Energy Technology Data Exchange (ETDEWEB)

    Yavuz, Yusuf [Anadolu Universitesi, Cevre Sor. Uyg. ve Aras. Merkezi, Eskisehir (Turkey); Koparal, A. Savas [Anadolu Universitesi, Cevre Sor. Uyg. ve Aras. Merkezi, Eskisehir (Turkey)]. E-mail: askopara@anadolu.edu.tr

    2006-08-21

    In this study, electrochemical oxidation of phenol was carried out in a parallel plate reactor using ruthenium mixed metal oxide electrode. The effects of initial pH, temperature, supporting electrolyte concentration, current density, flow rate and initial phenol concentration on the removal efficiency were investigated. Model wastewater prepared with distilled water and phenol, was recirculated to the electrochemical reactor by a peristaltic pump. Sodium sulfate was used as supporting electrolyte. The Microtox'' (registered) bioassay was also used to measure the toxicity of the model wastewater during the study. As a result of the study, removal efficiency of 99.7% and 88.9% were achieved for the initial phenol concentration of 200 mg/L and chemical oxygen demand (COD) of 480 mg/L, respectively. In the same study, specific energy consumption of 1.88 kWh/g phenol removed and, mass transfer coefficient of 8.62 x 10{sup -6} m/s were reached at the current density of 15 mA/cm{sup 2}. Electrochemical oxygen demand (EOD), which can be defined as the amount of electrochemically formed oxygen used for the oxidation of organic pollutants, was 2.13 g O{sub 2}/g phenol. Electrochemical oxidation of petroleum refinery wastewater was also studied at the optimum experimental conditions obtained. Phenol removal of 94.5% and COD removal of 70.1% were reached at the current density of 20 mA/cm{sup 2} for the petroleum refinery wastewater.

  6. Study for electrochemical behavior of uranium oxide in a molten LiCl-Li2O system

    International Nuclear Information System (INIS)

    Park, Sung Bin; Park, Byung Heung; Seo, Chung Seok; Jung, Ki Jung; Park, Seong Won

    2005-01-01

    Interest in the electrolytic reduction of uranium oxide is increasing in the treatment of spent fuel oxides. With complicated and expensive procedures many reactive metals can be prepared in a pure metal form, the electrochemical reduction of a metal oxide has been recently proposed in metallurgy. The electrochemical reduction process is simple and rapid when compared to the conventional processes. The process can reduce the production costs and be applicable to a wide range of metal oxides. Chen et al. proposed the direct electrochemical reduction of titanium dioxide to titanium in a molten calcium chloride. Argonne National Laboratory (ANL) has reported the experimental results of an electrochemical reduction of the uranium oxide fuel in a bench-scale apparatus with a cyclic voltammetry, and has designed high-capacity reduction (HCR) cells and conducted three kg-scale UO 2 reduction runs. Gourishankar et al. classified the mechanisms of the electrolytic reduction of the metal oxides in a LiCl-Li 2 O molten salt system into two types; the simultaneous reduction and the direct electrochemical reduction. The uranium oxide in LiCl-Li 2 O molten salt was converted to uranium metal according to two mechanisms. Korea Atomic Energy Research Institute (KAERI) has developed the Advanced Spent Fuel Conditioning Process (ACP) to be an innovative technology in handling the PWR spent fuel. As part of ACP, the electrolytic reduction process (ER process) is the electrochemical reduction process of uranium oxide to uranium metal in molten salt. The ER process has advantages in a technical stability, an economic potential and a good proliferation resistance. KAERI has reported on the good experimental results of an electrochemical reduction of the uranium oxide in a 20 kg HM/batch lab-scale. In this work, cyclic voltammograms for a LiCl-3 wt% Li 2 O system and an U 3 O 8 -LiCl-3 wt% Li 2 O system with the integrated cathode assembly have been obtained. From the cyclic

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

    Energy Technology Data Exchange (ETDEWEB)

    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 μm (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.

  8. Electrochemical processing of spent nuclear fuels: An overview of oxide reduction in pyroprocessing technology

    Directory of Open Access Journals (Sweden)

    Eun-Young Choi

    2015-12-01

    Full Text Available The electrochemical reduction process has been used to reduce spent oxide fuel to a metallic form using pyroprocessing technology for a closed fuel cycle in combination with a metal-fuel fast reactor. In the electrochemical reduction process, oxides fuels are loaded at the cathode basket in molten Li2O–LiCl salt and electrochemically reduced to the metal form. Various approaches based on thermodynamic calculations and experimental studies have been used to understand the electrode reaction and efficiently treat spent fuels. The factors that affect the speed of the electrochemical reduction have been determined to optimize the process and scale-up the electrolysis cell. In addition, demonstrations of the integrated series of processes (electrorefining and salt distillation with the electrochemical reduction have been conducted to realize the oxide fuel cycle. This overview provides insight into the current status of and issues related to the electrochemical processing of spent nuclear fuels.

  9. Structural and Electrochemical Properties of Lithium Nickel Oxide Thin Films

    Directory of Open Access Journals (Sweden)

    Gyu-bong Cho

    2014-01-01

    Full Text Available LiNiO2 thin films were fabricated by RF magnetron sputtering. The microstructure of the films was determined by X-ray diffraction and field-emission scanning electron microscopy. The electrochemical properties were investigated with a battery cycler using coin-type half-cells. The LiNiO2 thin films annealed below 500°C had the surface carbonate. The results suggest that surface carbonate interrupted the Li intercalation and deintercalation during charge/discharge. Although the annealing process enhanced the crystallization of LiNiO2, the capacity did not increase. When the annealing temperature was increased to 600°C, the FeCrNiO4 oxide phase was generated and the discharge capacity decreased due to an oxygen deficiency in the LiNiO2 thin film. The ZrO2-coated LiNiO2 thin film provided an improved discharge capacity compared to bare LiNiO2 thin film suggesting that the improved electrochemical characteristic may be attributed to the inhibition of surface carbonate by ZrO2 coating layer.

  10. Capsid protein oxidation in feline calicivirus using an electrochemical inactivation treatment

    Energy Technology Data Exchange (ETDEWEB)

    Shionoiri, Nozomi; Nogariya, Osamu; Tanaka, Masayoshi; Matsunaga, Tadashi; Tanaka, Tsuyoshi, E-mail: tsuyo@cc.tuat.ac.jp

    2015-02-11

    Highlights: • Feline calicivirus was inactivated electrochemically by a factor of >5 log. • The electrochemical treatment was performed at 0.9 V (vs. Ag/AgCl) for 15 min. • Electrochemical treatment caused oxidation of viral proteins. • Oxidation of viral proteins can lead to loss of viral structural integrity. - Abstract: Pathogenic viral infections are an international public health concern, and viral disinfection has received increasing attention. Electrochemical treatment has been used for treatment of water contaminated by bacteria for several decades, and although in recent years several reports have investigated viral inactivation kinetics, the mode of action of viral inactivation by electrochemical treatment remains unclear. Here, we demonstrated the inactivation of feline calicivirus (FCV), a surrogate for human noroviruses, by electrochemical treatment in a developed flow-cell equipped with a screen-printed electrode. The viral infectivity titer was reduced by over 5 orders of magnitude after 15 min of treatment at 0.9 V vs. Ag/AgCl. Proteomic study of electrochemically inactivated virus revealed oxidation of peptides located in the viral particles; oxidation was not observed in the non-treated sample. Furthermore, transmission electron microscopy revealed that viral particles in the treated sample had irregular structures. These results suggest that electrochemical treatment inactivates FCV via oxidation of peptides in the structural region, causing structural deformation of virus particles. This first report of viral protein damage through electrochemical treatment will contribute to broadening the understanding of viral inactivation mechanisms.

  11. Destination of organic pollutants during electrochemical oxidation of biologically-pretreated dye wastewater using boron-doped diamond anode

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xiuping [Department of Environmental Engineering, Peking University, the Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing100871 (China); Ni, Jinren, E-mail: nijinren@iee.pku.edu.cn [Department of Environmental Engineering, Peking University, the Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing100871 (China); Wei, Junjun; Xing, Xuan; Li, Hongna [Department of Environmental Engineering, Peking University, the Key Laboratory of Water and Sediment Sciences, Ministry of Education, Beijing100871 (China)

    2011-05-15

    Electrochemical oxidation of biologically-pretreated dye wastewater was performed in a boron-doped diamond (BDD) anode system. After electrolysis of 12 h, the COD was decreased from 532 to 99 mg L{sup -1} (<100 mg L{sup -1}, the National Discharge Standard of China). More importantly, the destination of organic pollutants during electrochemical oxidation process was carefully investigated by molecular weight distribution measurement, resin fractionation, ultraviolet-visible spectroscopy, HPLC and GC-MS analysis, and toxicity test. As results, most organic pollutants were completely removed by electrochemical oxidation and the rest was primarily degraded to simpler compounds (e.g., carboxylic acids and short-chain alkanes) with less toxicity, which demonstrated that electrochemical oxidation of biologically-pretreated dye wastewater with BDD anode was very effective and safe. Especially, the performance of BDD anode system in degradation of large molecular organics such as humic substances makes it very promising in practical applications as an advanced treatment of biologically-pretreated wastewaters.

  12. Nanocellulose: a promising nanomaterial for advanced electrochemical energy storage.

    Science.gov (United States)

    Chen, Wenshuai; Yu, Haipeng; Lee, Sang-Young; Wei, Tong; Li, Jian; Fan, Zhuangjun

    2018-04-23

    Nanocellulose has emerged as a sustainable and promising nanomaterial owing to its unique structures, superb properties, and natural abundance. Here, we present a comprehensive review of the current research activities that center on the development of nanocellulose for advanced electrochemical energy storage. We begin with a brief introduction of the structural features of cellulose nanofibers within the cell walls of cellulose resources. We then focus on a variety of processes that have been explored to fabricate nanocellulose with various structures and surface chemical properties. Next, we highlight a number of energy storage systems that utilize nanocellulose-derived materials, including supercapacitors, lithium-ion batteries, lithium-sulfur batteries, and sodium-ion batteries. In this section, the main focus is on the integration of nanocellulose with other active materials, developing films/aerogel as flexible substrates, and the pyrolyzation of nanocellulose to carbon materials and their functionalization by activation, heteroatom-doping, and hybridization with other active materials. Finally, we present our perspectives on several issues that need further exploration in this active research field in the future.

  13. Research Update: Nanoscale electrochemical transistors in correlated oxides

    Directory of Open Access Journals (Sweden)

    Teruo Kanki

    2017-04-01

    Full Text Available Large reversible changes of the electronic transport properties of solid-state oxide materials induced by electrochemical fields have received much attention as a new research avenue in iontronics. In this research update, dramatic transport changes in vanadium dioxide (VO2 nanowires were demonstrated by electric field-induced hydrogenation at room temperature through the nanogaps separated by humid air in a field-effect transistor structure with planar-type gates. This unique structure allowed us to investigate hydrogen intercalation and diffusion behavior in VO2 channels with respect to both time and space. Our results will contribute to further strategic researches to examine fundamental chemical and physical properties of devices and develop iontronic applications, as well as offering new directions to explore emerging functions for sensing, energy, and neuromorphologic devices combining ionic and electronic behaviors in solid-state materials.

  14. Current status of environmental, health, and safety issues of electrochemical capacitors for advanced vehicle applications

    Energy Technology Data Exchange (ETDEWEB)

    Vimmerstedt, L J; Hammel, C J

    1997-04-01

    Electrochemical capacitors are a candidate for traction power assists in hybrid electric vehicles (HEVs). Other advanced automotive applications, while not the primary focus of current development efforts, are also possible. These include load leveling high-energy batteries, power conditioning electronics, electrically hated catalysts, electric power steering, and engine starter power. Higher power and longer cycle life are expected for electrochemical capacitors than for batteries. Evaluation of environmental, health, and safety (EH and S) issues of electrochemical capacitors is an essential part of the development and commercialization of electrochemical capacitors for advanced vehicles. This report provides an initial EH and S assessment. This report presents electrochemical capacitor electrochemistry, materials selection, intrinsic material hazards, mitigation of those hazards, environmental requirements, pollution control options, and shipping requirements. Most of the information available for this assessment pertains to commercial devices intended for application outside the advanced vehicle market and to experiment or prototype devices. Electrochemical capacitors for power assists in HEVs are not produced commercially now. Therefore, materials for advanced vehicle electrochemical capacitors may change, and so would the corresponding EH and S issues. Although changes are possible, this report describes issues for likely electrochemical capacitor designs.

  15. Obtention of superconductivity by room temperature electrochemical oxidation of La2CuO4

    International Nuclear Information System (INIS)

    Casan-Pastor, N.; Fuertes, A.; Gomez-Romero, P.

    1993-01-01

    The undoped oxide La2CuO4 has required traditionally synthesis under high pressure of oxygen (and high temperatures) to incorporate excess oxygen into its structure and become a superconductor. The electrochemical oxidation of this same oxide at room temperature and pressure constitutes a striking example of the use of an alternative driving force for the oxidation of oxides to become superconductors. Electrochemical treatment of oxides has been frequently applied to their reduction with cationic intercalation. Oxidations of these solid with the concomitant intercalation of anions into their lattice shows also great promises. The paper reports recent results in the electrochemical oxidation of La2CuO4 and other cuprates, showing also the important role of post-oxidation thermal treatments on the properties of the resulting solids

  16. Electrochemical oxidation of butein at glassy carbon electrodes.

    Science.gov (United States)

    Tesio, Alvaro Yamil; Robledo, Sebastián Noel; Fernández, Héctor; Zon, María Alicia

    2013-06-01

    The electrochemical oxidation of flavonoid butein is studied at glassy carbon electrodes in phosphate and citrate buffer solutions of different pH values, and 1M perchloric acid aqueous solutions by cyclic and square wave voltammetries. The oxidation peak corresponds to the 2e(-), 2H(+) oxidation of the 3,4-dihydroxy group in B ring of butein, given the corresponding quinone species. The overall electrode process shows a quasi-reversible behavior and an adsorption/diffusion mixed control at high butein bulk concentrations. At low butein concentrations, the electrode process shows mainly an adsorption control. Butein surface concentration values were obtained from the charge associated with the adsorbed butein oxidation peaks, which are in agreement with those values expected for the formation of a monolayer of adsorbate in the concentration range from 1 to 5μM. Square wave voltammetry was used to perform a full thermodynamic and kinetics characterization of the butein surface redox couple. Therefore, from the combination of the "quasi-reversible maximum" and the "splitting of the net square wave voltammetric peak" methods, values of (0.386±0.003) V, (0.46±0.04), and 2.7×10(2)s(-1) were calculated for the formal potential, the anodic transfer coefficient, and the formal rate constant, respectively, of the butein overall surface redox process in pH4.00 citrate buffer solutions. These results will be then used to study the interaction of butein, and other flavonoids with the deoxyribonucleic acid, in order to better understand the potential therapeutic applications of these compounds. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. A reduced graphene oxide based electrochemical biosensor for tyrosine detection

    Science.gov (United States)

    Wei, Junhua; Qiu, Jingjing; Li, Li; Ren, Liqiang; Zhang, Xianwen; Chaudhuri, Jharna; Wang, Shiren

    2012-08-01

    In this paper, a ‘green’ and safe hydrothermal method has been used to reduce graphene oxide and produce hemin modified graphene nanosheet (HGN) based electrochemical biosensors for the determination of l-tyrosine levels. The as-fabricated HGN biosensors were characterized by UV-visible absorption spectra, fluorescence spectra, Fourier transform infrared spectroscopy (FTIR) spectra and thermogravimetric analysis (TGA). The experimental results indicated that hemin was successfully immobilized on the reduced graphene oxide nanosheet (rGO) through π-π interaction. TEM images and EDX results further confirmed the attachment of hemin on the rGO nanosheet. Cyclic voltammetry tests were carried out for the bare glass carbon electrode (GCE), the rGO electrode (rGO/GCE), and the hemin-rGO electrode (HGN/GCE). The HGN/GCE based biosensor exhibits a tyrosine detection linear range from 5 × 10-7 M to 2 × 10-5 M with a detection limitation of 7.5 × 10-8 M at a signal-to-noise ratio of 3. The sensitivity of this biosensor is 133 times higher than that of the bare GCE. In comparison with other works, electroactive biosensors are easily fabricated, easily controlled and cost-effective. Moreover, the hemin-rGO based biosensors demonstrate higher stability, a broader detection linear range and better detection sensitivity. Study of the oxidation scheme reveals that the rGO enhances the electron transfer between the electrode and the hemin, and the existence of hemin groups effectively electrocatalyzes the oxidation of tyrosine. This study contributes to a widespread clinical application of nanomaterial based biosensor devices with a broader detection linear range, improved stability, enhanced sensitivity and reduced costs.

  18. Electrochemical, H2O2-Boosted Catalytic Oxidation System

    Science.gov (United States)

    Akse, James R.; Thompson, John O.; Schussel, Leonard J.

    2004-01-01

    An improved water-sterilizing aqueous-phase catalytic oxidation system (APCOS) is based partly on the electrochemical generation of hydrogen peroxide (H2O2). This H2O2-boosted system offers significant improvements over prior dissolved-oxygen water-sterilizing systems in the way in which it increases oxidation capabilities, supplies H2O2 when needed, reduces the total organic carbon (TOC) content of treated water to a low level, consumes less energy than prior systems do, reduces the risk of contamination, and costs less to operate. This system was developed as a variant of part of an improved waste-management subsystem of the life-support system of a spacecraft. Going beyond its original intended purpose, it offers the advantage of being able to produce H2O2 on demand for surface sterilization and/or decontamination: this is a major advantage inasmuch as the benign byproducts of this H2O2 system, unlike those of systems that utilize other chemical sterilants, place no additional burden of containment control on other spacecraft air- or water-reclamation systems.

  19. Low temperature oxidation of hydrocarbons using an electrochemical reactor

    DEFF Research Database (Denmark)

    Ippolito, Davide

    conversion was a complex function of multiple variables: the microstructure of the backbone, the polarization resistance of the electrodes, both at OCV and under polarization, the electrical and morphological properties of the infiltrated material and the specific reaction conditions like the propene......This study investigated the use of a ceramic porous electrochemical reactor for the deep oxidation of propene. Two electrode composites, La0.85Sr0.15MnO3±d/Ce0.9Gd0.1O1.95 (LSM/CGO) and La0.85Sr0.15FeMnO3/Ce0.9Gd0.1O1.95 (LSF/CGO), were produced in a 5 single cells stacked configuration and used...... prolonged polarization was able to partially counteract the instability of the infiltrated Ce0.9Gd0.1O1.95. This project demonstrated the possibility to enhance the oxidation of propene by polarization in a porous ceramic reactor. The infiltration of different active materials helped to increase...

  20. Synthesis and electrochemical properties of tin oxide-based composite by rheological technique

    International Nuclear Information System (INIS)

    He Zeqiang; Li Xinhai; Xiong Lizhi; Wu Xianming; Xiao Zhuobing; Ma Mingyou

    2005-01-01

    Novel rheological technique was developed to synthesize tin oxide-based composites. The microstructure, morphology, and electrochemical performance of the materials were investigated by X-ray diffraction, scanning electron microscopy and electrochemical methods. The particles of tin oxide-based materials form an inactive matrix. The average size of the particles is about 150 nm. The material delivers a charge capacity of more than 570 mAh g -1 . The capacity loss per cycle is about 0.15% after being cycled 30 times. The good electrochemical performance indicates that this kind of tin oxide-based material is promising anode for lithium-ion battery

  1. Electrochemical synthesis of magnetic nanostructures using anodic aluminum oxide templates

    Science.gov (United States)

    Gong, Jie

    In this dissertation, template electrodeposition was employed to fabricate high quality magnetic nanostructures suited for the reliable investigation of novel spintronics phenomena such as CIMS, BMR, and CPP-GMR. Several critical aspects/steps relating to the synthesis process were investigated in this work. In order to obtain high quality magnetic nanostructures, free-standing and Si-supported anodic aluminum oxide templates with closely controlled pore diameters, lengths, as well as constriction sizes, were synthesized by anodization, followed by appropriate post-processing. The pore opening size on the barrier layer can be controlled down to 5 nm by ion beam etching. After optimization of the compositional, structural, and magnetic properties of homogeneous FeCoNiCu layers electrodeposited under different conditions, the pulsed deposition process of FeCoNI/Cu multilayers on n-Si was studied. The influence of Cu deposition potential and Fe2+ concentration on microstructure, chemical and electrochemical properties, magnetic properties, and hence magnetotransport properties were assessed. The dissolution of the FM layer during potential transition was minimized in order to control interface sharpness. Combined with the systematic sublayer thickness and FM layer composition optimization, unprecedented GMR sensitivity of 0.11%/Oe at 5-15 Oe was obtained. Growth of multilayer nanowires was performed, and contact to a single wire was attempted using an electrochemical technique. We succeeded in addressing a small number of nanowires and measured a CPP-GMR of 17%. Template electrodeposition thus provides a promising way to repeatably fabricate prototypes for spin dependent transport studies.

  2. Electrochemical Impedance Spectroscopy in Solid State Ionics: Recent Advances

    NARCIS (Netherlands)

    Boukamp, Bernard A.

    2004-01-01

    Electrochemical Impedance Spectroscopy (EIS) has become an important research tool in Solid State Ionics. Some new developments are highlighted: new methods of automatic parameter extraction from impedance measurements are briefly discussed. The Kramers–Kronig data validation test presents another

  3. ADVANCED OXIDATION PROCESSES (AOX) TEXTILE WASTEWATER

    OpenAIRE

    Salas C., G.

    2014-01-01

    Advanced Oxidation Processes (AOX) are based on the in situ generation of hydroxyradicals (·OH), which have a high oxidation potential. In the case of Fenton processes !he generation of hydroxy radicals takes place by the combination of an oxidation agent (H202) with a catalyst (Fe(II)). These radicals are not selective and they react very fast with the organic matter,being able to oxidize a high variety of organic compounds. This property allows the degradation of pollutants into more biodeg...

  4. Electrochemical performance of 3D porous Ni-Co oxide with electrochemically exfoliated graphene for asymmetric supercapacitor applications

    International Nuclear Information System (INIS)

    Kim, Dae Kyom; Hwang, Minsik; Ko, Dongjin; Kang, Jeongmin; Seong, Kwang-dong; Piao, Yuanzhe

    2017-01-01

    Graphical abstract: The paper reported the Ni-Co oxide/electrochemically exfoliated graphene nanocomposites with 3D porous nano-architectures (NC-EEG) using a simple low temperature solution method combined with a thermal annealing treatment. 3D porous architectures provide large surface areas and shorten electron diffusion pathways for high performance asymmetric supercapacitors. Display Omitted -- Highlights: •A simple low temperature solution method was used for preparing NC-EEG. •Graphene sheets were obtained by electrochemically exfoliation process. •A high capacity of NC-EEG in a three-electrode system, as high as 649 C g −1 , was recorded. •Asymmetric supercapacitor based on NC-EEG exhibited excellent energy density and power density. -- Abstract: Ni-Co oxide, one of the binary metal oxides, has many advantages for use in high-performance supercapacitor electrode materials due to its relatively high electronic conductivity and improved electrochemical performance. In this work, Ni-Co oxide/electrochemically exfoliated graphene nanocomposites (NC-EEG) are successfully synthesized using a simple low temperature solution method combined with a thermal annealing treatment. Graphene sheets are directly obtained by an electrochemical exfoliation process with graphite foil, which is very simple, environmentally friendly, and has a relatively short reaction time. This electrochemically exfoliated graphene (EEG) can improve the electrical conductivity of the Ni-Co oxide nanostructures. The as-prepared NC-EEG nanocomposites have 3D porous architectures that can provide large surface areas and shorten electron diffusion pathways. Electrochemical properties were performed by cyclic voltammetry and galvanostatic charge/discharge in a 6 M KOH electrolyte. The NC-EEG nanocomposites exhibited a high capacity value of 649 C g −1 at a current density of 1.0 A g −1 . The asymmetric supercapacitors, manufactured on the basis of NC-EEG nanocomposites as a positive

  5. Cycle aging studies of lithium nickel manganese cobalt oxide-based batteries using electrochemical impedance spectroscopy

    NARCIS (Netherlands)

    Maheshwari, Arpit; Heck, Michael; Santarelli, Massimo

    2018-01-01

    The cycle aging of a commercial 18650 lithium-ion battery with graphite anode and lithium nickel manganese cobalt (NMC) oxide-based cathode at defined operating conditions is studied by regular electrochemical characterization, electrochemical impedance spectroscopy (EIS) and post-mortem analysis.

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

    Science.gov (United States)

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

    2013-02-01

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

  7. Electrochemical reduction of nitrous oxide on La1-xSrxFeO3 perovskites

    DEFF Research Database (Denmark)

    Kammer Hansen, Kent

    2010-01-01

    The electrochemical reduction of nitrous oxide and oxygen has been studied on cone-shaped electrodes of La1-xSrxFeO3-delta perovskites in an all solid state cell, using cyclic voltammetry. It was shown that the activity of the La1-xSrxFeO3-delta perovskites for the electrochemical reduction...... of nitrous oxide mainly depends on the amount of Fe(III) and oxide ion vacancies. The activity of the La1-xSrxFeO3-delta perovskites towards the electrochemical reduction of nitrous oxide is much lower than the activity of the La1-xSrxFeO3-delta perovskites towards the electrochemical reduction of oxygen...

  8. Corrosion-electrochemical characteristics of oxide-carbide and oxide-nitride coatings formed by electrolytic plasma

    International Nuclear Information System (INIS)

    Tomashov, N.D.; Chukalovskaya, T.V.; Medova, I.L.; Duradzhi, V.N.; Plavnik, G.M.

    1990-01-01

    The composition, structure, microhardness and corrosion-electrochemical properties of oxide-carbide and oxide-nitride coatings on titanium in 5n H 2 SO 4 , 50 deg, produced by the method of chemical-heat treatment in electrolytic plasma, containing saturation components of nitrogen and carbon, were investigated. It is shown that the coatings produced have increased hardness, possess high corrosion resistance in sulfuric acid solution at increased temperature, as to their electrochemcial behaviour they are similar to titanium carbide and nitride respectively. It is shown that high corrosion resistance is ensured by electrochemical mechanism of the oxide-carbide and oxide-nitride coating protection

  9. Nanosized Ni-Mn Oxides Prepared by the Citrate Gel Process and Performances for Electrochemical Capacitors

    Institute of Scientific and Technical Information of China (English)

    Jianxin ZHOU; Xiangqian SHEN; Maoxiang JING

    2006-01-01

    Nanosized Ni-Mn oxide powders have been successfully prepared by thermal decomposition of the Ni-Mn citrate gel precursors. The powder materials derived from calcination of the gel precursors with various molar ratios of nickel and manganese at different temperatures and time were characterized using thermal analysis (TG-DSC), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Brunauer-Emmet-Teller (BET).The optimized processing conditions of calcination at 400℃ for 1 h with Ni/Mn molar ratio 6 were proved to produce the nanosized Ni-Mn oxide powders with a high specific surface area of 109.62 m2/g and nanometer particle sizes of 15~30 nm. The capacitance characteristics of the nanosized Ni-Mn oxide electrode in various concentrations of KOH solutions were studied by the cyclic voltammetry (CV) and exhibited both a doublelayer capacitance and a Faradaic capacitance which could be attributed to the electrode consisting of Ni-Mn oxides and residual carbons from the organic gel thermal decomposition. A specific capacitance of 194.8 F/g was obtained for the electrode at the sweep rate of 10 mV/s in 4 mol/L KOH electrolyte and the capacitor showed quite high cyclic stability and is promising for advanced electrochemical capacitors.

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

    Science.gov (United States)

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

    2013-08-07

    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.

  11. Nanoporous metal/oxide hybrid electrodes for electrochemical supercapacitors

    Science.gov (United States)

    Lang, Xingyou; Hirata, Akihiko; Fujita, Takeshi; Chen, Mingwei

    2011-04-01

    Electrochemical supercapacitors can deliver high levels of electrical power and offer long operating lifetimes, but their energy storage density is too low for many important applications. Pseudocapacitive transition-metal oxides such as MnO2 could be used to make electrodes in such supercapacitors, because they are predicted to have a high capacitance for storing electrical charge while also being inexpensive and not harmful to the environment. However, the poor conductivity of MnO2 (10-5-10-6 S cm-1) limits the charge/discharge rate for high-power applications. Here, we show that hybrid structures made of nanoporous gold and nanocrystalline MnO2 have enhanced conductivity, resulting in a specific capacitance of the constituent MnO2 (~1,145 F g-1) that is close to the theoretical value. The nanoporous gold allows electron transport through the MnO2, and facilitates fast ion diffusion between the MnO2 and the electrolytes while also acting as a double-layer capacitor. The high specific capacitances and charge/discharge rates offered by such hybrid structures make them promising candidates as electrodes in supercapacitors, combining high-energy storage densities with high levels of power delivery.

  12. Electrochemical and antimicrobial activity of tellurium oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Pramod K. [Department of Applied Sciences and Humanities, Jamia Millia Islamia, New Delhi 110067 (India); Special Centre for Nanosciences, Jawaharlal Nehru University, New Delhi 110067 (India); Sharma, Prem Prakash; Sharma, Anshu [Special Centre for Nanosciences, Jawaharlal Nehru University, New Delhi 110067 (India); Khan, Zishan H., E-mail: zishan_hk@yahoo.co.in [Department of Applied Sciences and Humanities, Jamia Millia Islamia, New Delhi 110067 (India); Solanki, Pratima R., E-mail: pratimarsolanki@gmail.com [Special Centre for Nanosciences, Jawaharlal Nehru University, New Delhi 110067 (India)

    2016-09-15

    Highlights: • TeO{sub 2} NPs synthesized without using any catalyst by chemical vapour deposition method. • The growth temperature was 410 °C with continuous flow of O{sub 2.} • TeO{sub 2} NPs have anti-bacterial activity against E. coli, K. pneumoniae and S. aureus while enhances the growth of S. pyogenes. • TeO{sub 2} shows maximum redox current at pH 7 for phosphate buffer solution. - Abstract: Thin film of tellurium oxide (TeO{sub 2}) has been synthesized by chemical vapour deposition method onto indium tin oxide (ITO) coated glass substrate without using any catalyst. XRD pattern of TeO{sub 2} thin film suggests that the structure of TeO{sub 2} changes from amorphous to crystalline (paratellurite) on dispersing into deionized water. Zeta potential measurement reveals a positive surface potential of 28.8 mV. TEM images shows spherical shaped TeO{sub 2} nanoparticles having average particle size of 65 nm. Electrochemical studies of TeO{sub 2}/ITO electrode exhibit improved electron transfer owing to its inherent electron transfer property at pH 7.0 of phosphate buffer. Antimicrobial activity of TeO{sub 2} has been studied for gram-positive (Staphylococcus aureus and Streptococcus pyogenes) and gram negative (Escherichia coli and Klebsiella pneumoniae) bacterial and fungal strains (Aspergillus nizer and Candida albicans). These studies suggest that the TeO{sub 2} NPs inhibit the growth of E. coli, K. pneumoniae and S. aureus bacteria, whereas the same particles enhance the growth of S. pyogenes bacteria.

  13. Electrochemical oxidation of textile industry wastewater by graphite electrodes.

    Science.gov (United States)

    Bhatnagar, Rajendra; Joshi, Himanshu; Mall, Indra D; Srivastava, Vimal C

    2014-01-01

    In the present article, studies have been performed on the electrochemical (EC) oxidation of actual textile industry wastewater by graphite electrodes. Multi-response optimization of four independent parameters namely initial pH (pHo): 4-10, current density (j): 27.78-138.89 A/m(2), NaCl concentration (w): 0-2 g/L and electrolysis time (t): 10-130 min have been performed using Box-Behnken (BB) experimental design. It was aimed to simultaneously maximize the chemical oxygen demand (COD) and color removal efficiencies and minimize specific energy consumption using desirability function approach. Pareto analysis of variance (ANOVA) showed a high coefficient of determination value for COD (R(2) = 0.8418), color (R(2) = 0.7010) and specific energy (R(2) = 0.9125) between the experimental values and the predicted values by a second-order regression model. Maximum COD and color removal and minimum specific energy consumed was 90.78%, 96.27% and 23.58 kWh/kg COD removed, respectively, were observed at optimum conditions. The wastewater, sludge and scum obtained after treatment at optimum condition have been characterized by various techniques. UV-visible study showed that all azo bonds of the dyes present in the wastewater were totally broken and most of the aromatic rings were mineralized during EC oxidation with graphite electrode. Carbon balance showed that out of the total carbon eroded from the graphite electrodes, 27-29.2% goes to the scum, 71.1-73.3% goes into the sludge and rest goes to the treated wastewater. Thermogravimetric analysis showed that the generated sludge and scum can be dried and used as a fuel in the boilers/incinerators.

  14. Electrochemical Properties of High Surface Area Vanadium Oxide Aerogels

    National Research Council Canada - National Science Library

    Dong, Winny

    2001-01-01

    .... Traditional composite electrode structures have prevented truly quantitative analysis of surface area effects in nanoscale battery materials, as well as a study of their innate electrochemical behavior...

  15. Solid-phase electrochemical reduction of graphene oxide films in alkaline solution

    Science.gov (United States)

    Basirun, Wan J.; Sookhakian, Mehran; Baradaran, Saeid; Mahmoudian, Mohammad R.; Ebadi, Mehdi

    2013-09-01

    Graphene oxide (GO) film was evaporated onto graphite and used as an electrode to produce electrochemically reduced graphene oxide (ERGO) films by electrochemical reduction in 6 M KOH solution through voltammetric cycling. Fourier transformed infrared and Raman spectroscopy confirmed the presence of ERGO. Electrochemical impedance spectroscopy characterization of ERGO and GO films in ferrocyanide/ferricyanide redox couple with 0.1 M KCl supporting electrolyte gave results that are in accordance with previous reports. Based on the EIS results, ERGO shows higher capacitance and lower charge transfer resistance compared to GO.

  16. Design and Electrochemical Study of Platinum-Based Nanomaterials for Sensitive Detection of Nitric Oxide in Biomedical Applications

    Directory of Open Access Journals (Sweden)

    Maduraiveeran Govindhan

    2016-11-01

    Full Text Available The extensive physiological and regulatory roles of nitric oxide (NO have spurred the development of NO sensors, which are of critical importance in neuroscience and various medical applications. The development of electrochemical NO sensors is of significant importance, and has garnered a tremendous amount of attention due to their high sensitivity and selectivity, rapid response, low cost, miniaturization, and the possibility of real-time monitoring. Nanostructured platinum (Pt-based materials have attracted considerable interest regarding their use in the design of electrochemical sensors for the detection of NO, due to their unique properties and the potential for new and innovative applications. This review focuses primarily on advances and insights into the utilization of nanostructured Pt-based electrode materials, such as nanoporous Pt, Pt and PtAu nanoparticles, PtAu nanoparticle/reduced graphene oxide (rGO, and PtW nanoparticle/rGO-ionic liquid (IL nanocomposites, for the detection of NO. The design, fabrication, characterization, and integration of electrochemical NO sensing performance, selectivity, and durability are addressed. The attractive electrochemical properties of Pt-based nanomaterials have great potential for increasing the competitiveness of these new sensors and open up new opportunities in the creation of novel NO-sensing technologies for biological and medical applications.

  17. Electrochemical advanced oxidation processes applied to the degradation of organic compounds in aqueous effluents; Aplicacion de procesos electroquimicos de oxidacion avanzada para la degradacion de compuestos organicos en efluentes acuosos

    Energy Technology Data Exchange (ETDEWEB)

    Peralta-Hernandez, J. M.; Maldonado, M. I.; Meas-Vong, Y.; Rodriguez, F.; Godinez, L. A.; Malato, S.

    2007-07-01

    Dyeing and finishing operations produce large quantities of wastewater that contains organic dyestuff, surfactants and other contaminants that can be characterized as high levels of total organic and color. Electro-Fenton (in situ electrochemical generation of the Fenton reagent) has been studied in order to exploit the fact that the reduction of dissolved oxygen to peroxide can be carried out selectively in acidic medium on the surface of a carbonaceous cathode. In this work, we report a study in which two approaches to water treatment are combined, photo catalysis and Fenton reaction, which involves the homogeneous conversion of peroxide to hydroxyl radical (OH). (Author) 140 refs.

  18. Metal Oxide Materials and Collector Efficiency in Electrochemical Supercapacitors

    Science.gov (United States)

    2010-12-01

    However, even if thick tita - nium films and/or nanostructured layers were obtained using these methods, they were composed of non-conducting titanium...following electrochemical reduction in LiClO4/acetonitrile. Table 1 reports the electrochemical parameters and the atomic composition of the tita - nium

  19. Advanced Proton Conducting Polymer Electrolytes for Electrochemical Capacitors

    Science.gov (United States)

    Gao, Han

    Research on solid electrochemical energy storage devices aims to provide high performance, low cost, and safe operation solutions for emerging applications from flexible consumer electronics to microelectronics. Polymer electrolytes, minimizing device sealing and liquid electrolyte leakage, are key enablers for these next-generation technologies. In this thesis, a novel proton-conducing polymer electrolyte system has been developed using heteropolyacids (HPAs) and polyvinyl alcohol for electrochemical capacitors. A thorough understanding of proton conduction mechanisms of HPAs together with the interactions among HPAs, additives, and polymer framework has been developed. Structure and chemical bonding of the electrolytes have been studied extensively to identify and elucidate key attributes affecting the electrolyte properties. Numerical models describing the proton conduction mechanism have been applied to differentiate those attributes. The performance optimization of the polymer electrolytes through additives, polymer structural modifications, and synthesis of alternative HPAs has achieved several important milestones, including: (a) high proton mobility and proton density; (b) good ion accessibility at electrode/electrolyte interface; (c) wide electrochemical stability window; and (d) good environmental stability. Specifically, high proton mobility has been addressed by cross-linking the polymer framework to improve the water storage capability at normal-to-high humidity conditions (e.g. 50-80% RH) as well as by incorporating nano-fillers to enhance the water retention at normal humidity levels (e.g. 30-60% RH). High proton density has been reached by utilizing additional proton donors (i.e. acidic plasticizers) and by developing different HPAs. Good ion accessibility has been achieved through addition of plasticizers. Electrochemical stability window of the electrolyte system has also been investigated and expanded by utilizing HPAs with different heteroatoms

  20. Microstructure characterizaton of advanced oxide fuel

    International Nuclear Information System (INIS)

    Rasmussen, D.E.; Gerber, E.W.; McCord, R.B.

    1977-01-01

    Preirradiation porosity, grain size, and microcomposition characteristics are presented for selected advanced oxide (PuO 2 -UO 2 ) LMFBR developmental fuels fabricated for irradiation testing in EBR-II. Quantitative microscopy, electron microprobe analysis, and a recently developed quantitative autoradiographic technique are utilized to relate microstructure characteristics to fabrication parameters

  1. Review of Fabrication Methods, Physical Properties, and Applications of Nanostructured Copper Oxides Formed via Electrochemical Oxidation

    Directory of Open Access Journals (Sweden)

    Wojciech J. Stepniowski

    2018-05-01

    Full Text Available Typically, anodic oxidation of metals results in the formation of hexagonally arranged nanoporous or nanotubular oxide, with a specific oxidation state of the transition metal. Recently, the majority of transition metals have been anodized; however, the formation of copper oxides by electrochemical oxidation is yet unexplored and offers numerous, unique properties and applications. Nanowires formed by copper electrochemical oxidation are crystalline and composed of cuprous (CuO or cupric oxide (Cu2O, bringing varied physical and chemical properties to the nanostructured morphology and different band gaps: 1.44 and 2.22 eV, respectively. According to its Pourbaix (potential-pH diagram, the passivity of copper occurs at ambient and alkaline pH. In order to grow oxide nanostructures on copper, alkaline electrolytes like NaOH and KOH are used. To date, no systemic study has yet been reported on the influence of the operating conditions, such as the type of electrolyte, its temperature, and applied potential, on the morphology of the grown nanostructures. However, the numerous reports gathered in this paper will provide a certain view on the matter. After passivation, the formed nanostructures can be also post-treated. Post-treatments employ calcinations or chemical reactions, including the chemical reduction of the grown oxides. Nanostructures made of CuO or Cu2O have a broad range of potential applications. On one hand, with the use of surface morphology, the wetting contact angle is tuned. On the other hand, the chemical composition (pure Cu2O and high surface area make such materials attractive for renewable energy harvesting, including water splitting. While compared to other fabrication techniques, self-organized anodization is a facile, easy to scale-up, time-efficient approach, providing high-aspect ratio one-dimensional (1D nanostructures. Despite these advantages, there are still numerous challenges that have to be faced, including the

  2. Effects of p-substituents on electrochemical CO oxidation by Rh porphyrin-based catalysts.

    Science.gov (United States)

    Yamazaki, Shin-ichi; Yamada, Yusuke; Takeda, Sahori; Goto, Midori; Ioroi, Tsutomu; Siroma, Zyun; Yasuda, Kazuaki

    2010-08-21

    Electrochemical CO oxidation by several carbon-supported rhodium tetraphenylporphyrins with systematically varied meso-substituents was investigated. A quantitative analysis revealed that the p-substituents on the meso-phenyl groups significantly affected CO oxidation activity. The electrocatalytic reaction was characterized in detail based on the spectroscopic and X-ray structural results as well as electrochemical analyses. The difference in the activity among Rh porphyrins is discussed in terms of the properties of p-substituents along with a proposed reaction mechanism. Rhodium tetrakis(4-carboxyphenyl)porphyrin (Rh(TCPP)), which exhibited the highest activity among the porphyrins tested, oxidized CO at a high rate at much lower potentials (means that CO is electrochemically oxidized by this catalyst when a slight overpotential is applied during the operation of a proton exchange membrane fuel cell. This catalyst exhibited little H(2) oxidation activity, in contrast to Pt-based catalysts.

  3. Electrochemical oxidation of propene by use of LSM15/CGO10 electrochemical reactor

    DEFF Research Database (Denmark)

    Ippolito, Davide; Andersen, Kjeld Bøhm; Kammer Hansen, Kent

    2012-01-01

    The propene catalytic oxidation was studied over an 11-layers porous electrochemical reactor made by La0.85Sr0.15MnO3 and Ce0.9Gd0.1O1.95 with the objective to simulate the abatement of exhaust gases emitted from Diesel engines. This work shows the possibility to enhance the catalytic activity th...... of catalysis (EPOC) was found at low temperature....

  4. Electrochemical combustion of indigo at ternary oxide coated titanium anodes

    Directory of Open Access Journals (Sweden)

    María I. León

    2014-12-01

    Full Text Available The film of iridium and tin dioxides doped with antimony (IrO2-SnO2–Sb2O5 deposited on a Ti substrate (mesh obtained by Pechini method was used for the formation of ·OH radicals by water discharge. Detection of ·OH radicals was followed by the use of the N,N-dimethyl-p-nitrosoaniline (RNO as a spin trap. The electrode surface morphology and composition was characterized by SEM-EDS. The ternary oxide coating was used for the electrochemical combustion of indigo textile dye as a model organic compound in chloride medium. Bulk electrolyses were then carried out at different volumetric flow rates under galvanostatic conditions using a filter-press flow cell. The galvanostatic tests using RNO confirmed that Ti/IrO2-SnO2-Sb2O5 favor the hydroxyl radical formation at current densities between 5 and 7 mA cm-2, while at current density of 10 mA cm-2 the oxygen evolution reaction occurs. The indigo was totally decolorized and mineralized via reactive oxygen species, such as (·OH, H2O2, O3 and active chlorine formed in-situ at the Ti/IrO2-SnO2-Sb2O5 surface at volumetric flow rates between 0.1-0.4 L min-1 and at fixed current density of 7 mA cm-2. The mineralization of indigo carried out at 0.2 L min-1 achieved values of 100 %, with current efficiencies of 80 % and energy consumption of 1.78 KWh m-3.

  5. Electrochemical Oxidation and Detection of Sodium Urate in ...

    African Journals Online (AJOL)

    DR. MIKE HORSFALL

    3 Delft University of Technology, 2600 GA Delft, The Netherlands. ABSTRACT: ... both sodium urate and mixture of urate and tartrate as a cumulative response, in alkaline media, the target ..... electrochemical oxygen demand (EOD) using a.

  6. Optimization of reaction parameters for the electrochemical oxidation of lidocaine with a Design of Experiments approach

    NARCIS (Netherlands)

    Gul, Turan; Bischoff, Rainer; Permentier, Hjalmar

    2015-01-01

    Identification of potentially toxic oxidative drug metabolites is a crucial step in the development of new drugs. Electrochemical methods are useful to study oxidative drug metabolism, but are not widely used to synthesize metabolites for follow-up studies. Careful optimization of reaction

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

    International Nuclear Information System (INIS)

    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

  8. Studies on room temperature electrochemical oxidation and its effect on the transport properties of TBCCO films

    International Nuclear Information System (INIS)

    Shirage, P M; Shivagan, D D; Pawar, S H

    2004-01-01

    A novel room temperature electrochemical process for the synthesis of single-phase Tl 2 Ba 2 Ca 2 Cu 3 O 10 (TBCCO/Tl-2223) superconducting films has been developed. Electrochemical parameters were optimized by studying linear sweep voltammetry (LSV), cyclic voltammetry (CV) and chronoamperometry (CA) for the deposition of Tl-Ba-Ca-Cu alloy at room temperature. The superconducting films of the TBCCO were obtained by two oxidation techniques. In the first technique, the electrodeposited Tl-Ba-Ca-Cu alloyed films were oxidized at various temperatures in flowing oxygen atmosphere. In the second technique, stoichiometric electrocrystallization to get Tl 2 Ba 2 Ca 2 Cu 3 O 10 (Tl-2223) was completed by electrochemically intercalating oxygen species into Tl-Ba-Ca-Cu alloy at room temperature for various lengths of time. The oxygen content in the samples was varied by varying the electrochemical oxidation period, and the changes in the crystal structure, superconducting transition temperature (T c ) and critical current density (J c ) were recorded. The high temperature furnace oxidation technique was replaced by the room temperature electrochemical oxidation technique. The dependence of superconducting parameters on oxygen content is correlated with structure-property relations

  9. Kinetic studies of electrochemical generation of Ag(II) ion and catalytic oxidation of selected organics

    International Nuclear Information System (INIS)

    Zawodzinski, C.; Smith, W.H.; Martinez, K.R.

    1993-01-01

    The goal of this research is to develop a method to treat mixed hazardous wastes containing selected organic compounds and heavy metals, including actinide elements. One approach is to destroy the organic via electrochemical oxidation to carbon dioxide, then recover the metal contaminants through normally accepted procedures such as ion exchange, precipitation, etc. The authors have chosen to study the electrochemical oxidation of a simple alcohol, iso-propanol. Much of the recent work reported involved the use of an electron transfer mediator, usually the silver(I)/(II) redox couple. This involved direct electrochemical generation of the mediator at the anode of a divided cell followed by homogeneous reaction of the mediator with the organic compound. In this study the authors have sought to compare the mediated reaction with direct electrochemical oxidation of the organic. In addition to silver(I)/(II) they also looked at the cobalt(II)/(III) redox coupled. In the higher oxidation state both of these metal ions readily hydrolyze in aqueous solution to ultimately form insoluble oxide. The study concluded that in a 6M nitric acid solution at room temperature iso-propanol can be oxidized to carbon dioxide and acetic acid. Acetic acid is a stable intermediate and resists further oxidation. The presence of Co(III) enhances the rate or efficiency of the reaction

  10. Electrochemical characterization of oxide film formed at high temperature on Alloy 690

    Energy Technology Data Exchange (ETDEWEB)

    Abraham, Geogy J., E-mail: gja@barc.gov.in [Materials Science Division, BARC, Mumbai 400 085 (India); Bhambroo, Rajan [Deptt. of Metallurgical Engg. and Mat. Sci., IIT Bombay, Mumbai 400 076 (India); Kain, V. [Materials Science Division, BARC, Mumbai 400 085 (India); Shekhar, R. [CCCM, BARC, Hyderabad 500 062 (India); Dey, G.K. [Materials Science Division, BARC, Mumbai 400 085 (India); Raja, V.S. [Deptt. of Metallurgical Engg. and Mat. Sci., IIT Bombay, Mumbai 400 076 (India)

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer GD-QMS studies of high temperature oxide film formed on Alloy 690. Black-Right-Pointing-Pointer Defect density reduced with increase in temperature. Black-Right-Pointing-Pointer Electrochemical behaviour of oxide film correlated to the Cr-content in oxide. - Abstract: High temperature passivation studies on Alloy 690 were carried out in lithiated water at 250 Degree-Sign C, 275 Degree-Sign C and 300 Degree-Sign C for 72 h. The passive films were characterized by glow discharge-quadrupole mass spectroscopy (GD-QMS) for compositional variation across the depth and micro laser Raman spectroscopy for oxide composition on the surface. The defect density in the oxide films was established from the Mott-Schottky analysis using electrochemical impedance spectroscopy. Electrochemical experiments at room temperature in chloride medium revealed best passivity behaviour by the oxide film formed at 300 Degree-Sign C for 72 h. The electrochemical studies were correlated to the chromium (and oxygen) content of the oxide films. Autoclaving at 300 Degree-Sign C resulted in the best passive film formation on Alloy 690 in lithiated water.

  11. Electrochemical oxidation of methanol and formic acid in fuel cell processes

    Energy Technology Data Exchange (ETDEWEB)

    Seland, Frode

    2005-07-01

    The main objectives of the thesis work were: (1), to study the oxidation of methanol and formic acid on platinum electrodes by employing conventional and advanced electrochemical methods, and (2), to develop membrane electrode assemblies based on polybenzimidazole membranes that can be used in fuel cells up to 200 C. D.c. voltammetry and a.c. voltammetry studies of methanol and formic acid on polycrystalline platinum in sulphuric acid electrolyte were performed to determine the mechanism and kinetics of the oxidation reactions. A combined potential step and fast cyclic voltammetry experiment was employed to investigate the time dependence primarily of methanol oxidation on platinum. Charge measurements clearly demonstrated the existence of a parallel path at low potentials and short times without formation of adsorbed CO. Furthermore, experimental results showed that only the serial path, via adsorbed CO, exists during continuous cycling, with the first step being diffusion controlled dissociative adsorption of methanol directly from the bulk electrolyte. The saturation charge of adsorbed CO derived from methanol was found to be significantly lower than CO derived from formic acid or dissolved CO. This was attributed to the site requirements of the dehydrogenation steps, and possibly different compositions of linear, bridged or multiply bonded CO. The coverage of adsorbed CO from formic acid decreased significantly at potentials just outside of the hydrogen region (0.35 V vs. RHE), while it did not start to decrease significantly until about 0.6 V vs. RHE for methanol. Adsorbed CO from dissolved CO rapidly oxidized at potentials above about 0.75 V due to formation of platinum oxide. Data from a.c. voltammograms from 0.5 Hz up to 30 kHz were assembled into electrochemical impedance spectra (EIS) and analyzed using equivalent circuits. The main advantages of collecting EIS spectra from a.c. voltammetry experiments are the ability to directly correlate the impedance

  12. Preparation and electrochemical characterization of MnOOH nanowire-graphene oxide

    International Nuclear Information System (INIS)

    Wang Lin; Wang Dianlong

    2011-01-01

    Highlights: → MnOOH nanowire-graphene oxide composites are prepared by hydrothermal reaction in distilled water or 5% ammonia aqueous solution at 130 deg. C, with MnO 2 -graphene oxide composites which are synthesized by a redox reaction between KMnO 4 and graphene oxide. → MnO 2 is deoxidized to MnOOH on graphene oxide through hydrothermal reaction without any extra reductants. → It is found that the electrochemical resistance of MnOOH nanowire-graphene oxide composites decreases and the capacitance increases to 76 F g -1 when hydrothermal reaction is conducted in ammonia aqueous solution. → MnOOH nanowire-graphene oxide composites prepared by hydrothermal reaction in 5% ammonia aqueous solution have excellent capacitance retention ratio at scan rate from 5 mV s -1 to 40 mV s -1 . - Abstract: MnOOH nanowire-graphene oxide composites are prepared by hydrothermal reaction in distilled water or 5% ammonia aqueous solution at 130 deg. C with MnO 2 -graphene oxide composites which are synthesized by a redox reaction between KMnO 4 and graphene oxide. Powder X-ray diffraction (XRD) analyses and energy dispersive X-ray analyses (EDAX) show MnO 2 is deoxidized to MnOOH on graphene oxide through hydrothermal reaction without any extra reductants. The electrochemical capacitance of MnOOH nanowire-graphene oxide composites prepared in 5% ammonia aqueous solution is 76 F g -1 at current density of 0.1 A g -1 . Moreover, electrochemical impedance spectroscopy (EIS) suggests the electrochemical resistance of MnOOH nanowire-graphene oxide composites is reduced when hydrothermal reaction is conducted in ammonia aqueous solution. The relationship between the electrochemical capacitance and the structure of MnOOH nanowire-graphene oxide composites is characterized by cyclic voltammetry (CV) and field emission scanning electron microscopy (FESEM). The results indicate the electrochemical performance of MnOOH nanowire-graphene oxide composites strongly depends on their

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

    Science.gov (United States)

    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 20 min at different initial concentrations (0.5-20 mg L(-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 30 min, 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 (20 mg L(-1)) degradation with Ti/SnO2-Sb/Ce-PbO2 anode at the optimal current densities from 2 to 16 mA cm(-2) ranged from 8.21 to 18.73 kWh m(-3). Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Recent advances in transition-metal dichalcogenides based electrochemical biosensors: A review.

    Science.gov (United States)

    Wang, Yi-Han; Huang, Ke-Jing; Wu, Xu

    2017-11-15

    Layered transition metal dichalcogenides (TMDCs) comprise a category of two-dimensional (2D) materials that offer exciting properties, including large surface area, metallic and semi-conducting electrical capabilities, and intercalatable morphologies. Biosensors employ biological molecules to recognize the target and utilize output elements which can translate the biorecognition event into electrical, optical or mass-sensitive signals to determine the quantities of the target. TMDCs nanomaterials have been widely applied in various electrochemical biosensors with high sensitivity and selectivity. The marriage of TMDCs and electrochemical biosensors has created many productive sensing strategies for applications in the areas of clinical diagnosis, environmental monitoring and food safety. In recent years, an increasing number of TMDCs-based electrochemical biosensors are reported, suggesting TMDCs offers new possibilities of improving the performance of electrochemical biosensors. This review summarizes recent advances in electrochemical biosensors based on TMDCs for detection of various inorganic and organic analytes in the last five years, including glucose, proteins, DNA, heavy metal, etc. In addition, we also point out the challenges and future perspectives related to the material design and development of TMDCs-based electrochemical biosensors. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. A novel advanced oxidation process——wet electrocatalytic oxidation for high concentrated organic wastewater treatment

    Institute of Scientific and Technical Information of China (English)

    DAI QiZhou; ZHOU MingHua; LEI LeCheng; ZHANG Xing Wang

    2007-01-01

    A novel advanced oxidation process-wet electrocatalytic oxidation(WEO)was studied with p-nitrophenol as model pollutant and β-PbO2 electrode as the anode.Compared with the effect of the individual wet air oxidation(WAO)and electrochemical oxidation(EO),the effect of WEO showed synergistic effect on COD removal under the conditions of temperature 160℃,C=1000mg·L-1,PN2=0.50MPa,Po2=0.9 MPa,current density=3 mA·cm-2,Na2SO4 3 g·L-1.And the synergistic factor got the best value of 0.98 within 120 min after 180 min treatment.The synergistic factor was studied after 120 min treatment at 100℃,120℃,140℃and 160℃,and the effect of 120℃was the best with the value of 1.26.Possible mechanism for the synergistic effect was discussed based on the analysis of free-radical generation and intermediates detected by HPLC and GC/MS.

  16. Effect of electrochemical oxidation of a viscose rayon based ...

    African Journals Online (AJOL)

    A viscose rayon based activated carbon cloth (ACC) was electrochemically oxidised to enhance its cation sorption capacity for comparison with as-received ACC. ACCs were characterised by sodium capacity measurement, pH titration, zeta potential measurement, elemental analysis, Brunauer-Emmet- Teller surface area ...

  17. Electrochemical Impedance Modeling of a Solid Oxide Fuel Cell Anode

    DEFF Research Database (Denmark)

    Mohammadi, R.; Søgaard, Martin; Ramos, Tania

    2014-01-01

    (TLM), which is suitably modified to account for the electrode microstructural details, is used for modeling the impedance arising from the electrochemical reactions. In order to solve the system of nonlinear equations, an in-house code based on the finite difference method was developed. Some...

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

    International Nuclear Information System (INIS)

    Cheng, Liang; Shao, Mingwang; Chen, Dayan; Zhang, Yuzhong

    2010-01-01

    Mesoporous CuO was successfully synthesized via thermal decomposition of CuC 2 O 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.

  19. Direct electrochemical imidation of aliphatic amines via anodic oxidation.

    Science.gov (United States)

    Zhang, Li; Su, Ji-Hu; Wang, Sujing; Wan, Changfeng; Zha, Zhenggen; Du, Jiangfeng; Wang, Zhiyong

    2011-05-21

    Direct electrochemical synthesis of sulfonyl amidines from aliphatic amines and sulfonyl azides was realized with good to excellent yields. Traditional tertiary amine substrates were broadened to secondary and primary amines. The reaction intermediates were observed and a reaction mechanism was proposed and discussed. © The Royal Society of Chemistry 2011

  20. Electrochemical potentials of layered oxide and olivine phosphate ...

    Indian Academy of Sciences (India)

    Lithium ion battery; cathodes; density functional theory; density of states; Bader charge analysis; electrochemical ... voltage, ionic diffusion coefficient, phase stability and charge ... routes to synthesis and fabrication techniques. .... from the lithiated one. ..... Ebner W, Fouchard D and Xie L 1994 Solid State Ionics 69 238.

  1. Small-angle neutron scattering and cyclic voltammetry study on electrochemically oxidized and reduced pyrolytic carbon

    International Nuclear Information System (INIS)

    Braun, A.; Kohlbrecher, J.; Baertsch, M.; Schnyder, B.; Koetz, R.; Haas, O.; Wokaun, A.

    2004-01-01

    The electrochemical double layer capacitance and internal surface area of a pyrolytic carbon material after electrochemical oxidation and subsequent reduction was studied with cyclic voltammetry and small-angle neutron scattering. Oxidation yields an enhanced internal surface area (activation), and subsequent reduction causes a decrease of this internal surface area. The change of the Porod constant, as obtained from small-angle neutron scattering, reveals that the decrease in internal surface area is not caused merely by a closing or narrowing of the pores, but by a partial collapse of the pore network

  2. Waste treatment in NUCEF facility with silver mediated electrochemical oxidation technique

    International Nuclear Information System (INIS)

    Umeda, M.; Sugikawa, S.

    2000-01-01

    Silver mediated electrochemical oxidation technique has been considered one of promising candidates for alpha-bearing waste treatment. Destruction tests of organic compounds, such as insoluble tannin, TBP and dodecane, were carried out by this technique and the experimental data such as destruction rates, current efficiencies and intermediates were obtained. These compounds could be completely mineralized without the formation of reactive organic nitrate associated to safety hazards. On the basis of these results, the applicability of silver mediated electrochemical oxidation technique to waste treatment in NUCEF was evaluated. (authors)

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

    International Nuclear Information System (INIS)

    Gupta, Vinay; Kawaguchi, Toshikazu; Miura, Norio

    2009-01-01

    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 3 O 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 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

  4. Oxidation mechanism of flavanone taxifolin. Electrochemical and spectroelectrochemical investigation

    International Nuclear Information System (INIS)

    Kocábová, Jana; Fiedler, Jan; Degano, Ilaria; Sokolová, Romana

    2016-01-01

    Highlights: • The oxidation mechanism of flavanone taxifolin was proposed. • The oxidation is specific and differs from oxidation of flavonol quercetin. • A benzofuranon common for quercetin is NOT the taxifolin oxidation product. • The absence of C2–C3 double bond is crucial in taxifolin oxidation. - Abstract: The oxidation of taxifolin on glassy carbon electrode in acetonitrile was studied by cyclic voltammetry, UV–vis and IR spectroelectrochemistry. The oxidation products were identified using HPLC-ESI-MS/MS. The two-electron oxidation mechanism differs from that of flavonols (e.g. quercetin) due to the absence of the double bond between atoms C-2 and C-3. As confirmed by IR spectroelectrochemistry, quinone at ring B is formed as low stable intermediate. The oxidation pathway leads to the formation of hydroxylated derivative of taxifolin 2′,3,3′,4′,5,7-hexahydroxyflavone accompanied by the 2,3-desaturation.

  5. Characterization of Schottky barrier diodes fabricated from electrochemical oxidation of {alpha} phase brass

    Energy Technology Data Exchange (ETDEWEB)

    Bond, John W., E-mail: jwb13@le.ac.u [Forensic Research Centre, University of Leicester, Leicester LE1 7 EA (United Kingdom)

    2011-04-01

    By careful selection of chloride ion concentration in aqueous sodium chloride, electrochemical oxidation of {alpha} phase brass is shown to permit fabrication of either p-type copper (I) oxide/metal or n-type zinc oxide/metal Schottky barrier diodes. X-ray photoelectron and Auger electron spectroscopies provide evidence that barrier formation and rectifying qualities depend on the relative surface abundance of copper (I) oxide and zinc oxide. X-ray diffraction of the resulting diodes shows polycrystalline oxides embedded in amorphous oxidation products that have a lower relative abundance than the diode forming oxide. Conventional I/V characteristics of these diodes show good rectifying qualities. When neither of the oxides dominate, the semiconductor/metal junction displays an absence of rectification.

  6. An electrochemical study of the flow rate effect on the oxide film of SA106 Gr.C piping

    International Nuclear Information System (INIS)

    Hong, S. M.; Kim, J. H.; Kim, I. S.

    2002-01-01

    Effect of water flow rate on the oxide film of SA106 Gr.C piping was evaluated quantitatively through electrochemical method. It was carried out with weight change experiments, polarization tests, and EIS tests with rig that simulates water flow. Without water flow, the oxide film is so stable that it effectively blocks current exchange. With water flow, the oxide film was damaged and electrochemical current density and oxide film properties, C dl and R p were significantly changed

  7. Recent advances in the electrochemical construction of heterocycles

    Directory of Open Access Journals (Sweden)

    Robert Francke

    2014-12-01

    Full Text Available Due to the fact that the major portion of pharmaceuticals and agrochemicals contains heterocyclic units and since the overall number of commercially used heterocyclic compounds is steadily growing, heterocyclic chemistry remains in the focus of the synthetic community. Enormous efforts have been made in the last decades in order to render the production of such compounds more selective and efficient. However, most of the conventional methods for the construction of heterocyclic cores still involve the use of strong acids or bases, the operation at elevated temperatures and/or the use of expensive catalysts and reagents. In this regard, electrosynthesis can provide a milder and more environmentally benign alternative. In fact, numerous examples for the electrochemical construction of heterocycles have been reported in recent years. These cases demonstrate that ring formation can be achieved efficiently under ambient conditions without the use of additional reagents. In order to account for the recent developments in this field, a selection of representative reactions is presented and discussed in this review.

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

    Science.gov (United States)

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

    2014-11-01

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

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

    International Nuclear Information System (INIS)

    Shou Qingliang; Cheng Jipeng; Zhang Li; Nelson, Bradley J.; Zhang Xiaobin

    2012-01-01

    We report a one-step synthesis of a nanocomposite of goethite (α-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 −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: ► Ferrous ions act as reductant of graphite oxide and precursor of goethite nanorods. ► Goethite nanorods are attached on both sides of the reduced graphene oxide sheets. ► Composite exhibits a high specific capacitance and a good recycling capability. ► Composite is promising for supercapacitor applications.

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

    Science.gov (United States)

    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=1 mA cm(-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. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Electrochemical oxidation of 4-morpholinoaniline in aqueous solutions: Synthesis of a new trimer of 4-morpholinoaniline

    International Nuclear Information System (INIS)

    Esmaili, Roya; Nematollahi, Davood

    2011-01-01

    Research highlights: → Electrochemical study of 4-morpholinoaniline in various pHs. → Electrochemical trimerization of 4-morpholinoaniline in aqueous solution. → Green method for the synthesis of '4-morpholinoaniline-trimer'. → Potential-pH diagram for 4-morpholinoaniline. - Abstract: Electrochemical oxidation of 4-morpholinoaniline has been studied in various pHs using cyclic voltammetry and controlled-potential coulometry. The electrochemical trimerization of 4-morpholinoaniline is described and its mechanism has been studied in aqueous solution. This method provides a green, reagent-less, and environmentally friendly procedure with high atom economy, for the synthesis of '4-morpholinoaniline-trimer' using a carbon electrode in an undivided cell in good yield and purity.

  12. Thermally Reduced Graphene Oxide Electrochemically Activated by Bis-Spiro Quaternary Alkyl Ammonium for Capacitors.

    Science.gov (United States)

    He, Tieshi; Meng, Xiangling; Nie, Junping; Tong, Yujin; Cai, Kedi

    2016-06-08

    Thermally reduced graphene oxide (RGO) electrochemically activated by a quaternary alkyl ammonium-based organic electrolytes/activated carbon (AC) electrode asymmetric capacitor is proposed. The electrochemical activation process includes adsorption of anions into the pores of AC in the positive electrode and the interlayer intercalation of cations into RGO in the negative electrode under high potential (4.0 V). The EA process of RGO by quaternary alkyl ammonium was investigated by X-ray diffraction and electrochemical measurements, and the effects of cation size and structure were extensively evaluated. Intercalation by quaternary alkyl ammonium demonstrates a small degree of expansion of the whole crystal lattice (d002) and a large degree of expansion of the partial crystal lattice (d002) of RGO. RGO electrochemically activated by bis-spiro quaternary alkyl ammonium in propylene carbonate/AC asymmetric capacitor exhibits good activated efficiency, high specific capacity, and stable cyclability.

  13. V2O5 xerogel-poly(ethylene oxide) hybrid material: Synthesis, characterization, and electrochemical properties

    International Nuclear Information System (INIS)

    Guerra, Elidia M.; Ciuffi, Katia J.; Oliveira, Herenilton P.

    2006-01-01

    In this work, we report the synthesis, characterization, and electrochemical properties of vanadium pentoxide xerogel-poly(ethylene oxide) (PEO) hybrid materials obtained by varying the average molecular weight of the organic component as well as the components' ratios. The materials were characterized by X-ray diffraction, ultraviolet/visible and infrared spectroscopies, thermogravimetric analysis, scanning electron microscopy, electron paramagnetic resonance, and cyclic voltammetry. Despite the presence of broad and low intensity peaks, the X-ray diffractograms indicate that the lamellar structure of the vanadium pentoxide xerogel is preserved, with increase in the interplanar spacing, giving evidence of a low-crystalline structure. We found that the electrochemical behaviour of the hybrid materials is quite similar to that found for the V 2 O 5 xerogel alone, and we verified that PEO leads to stabilization and reproducibility of the Li + electrochemical insertion/de-insertion into the V 2 O 5 xerogel structure, which makes these materials potential components of lithium ion batteries. - Graphical abstract: The synthesis, structural and electrochemical properties of vanadium pentoxide xerogel-poly(ethylene oxide) hybrid materials have been described. Despite the presence of broad and low intensity peaks, the X-ray diffractograms indicate that the lamellar structure of the vanadium pentoxide xerogel is preserved. The cyclic voltammetry technique demonstrated that PEO intercalation provides an improvement in the electrochemical properties, mainly with respect to the lithium electroinsertion process into the oxide matrix

  14. Chitosan/graphene oxide nanocomposite films with enhanced interfacial interaction and their electrochemical applications

    International Nuclear Information System (INIS)

    He, Linghao; Wang, Hongfang; Xia, Guangmei; Sun, Jing; Song, Rui

    2014-01-01

    Graphical abstract: Nanocomposites by introducing graphene oxide (GO) into chitosan (CS) matrix were prepared and the effect of GO on the crystallization, thermal stability and mechanical properties of the films were investigated. In addition, the electrochemical behavior of the CS/GO modified electrode was comparatively studied with that of the neat CS-modified electrode. - Highlights: • Graphene oxide (GO) with well dispersion in the biopolymer chitosan (CS) matrix. • Detectable interactions do exist between the GO nanosheets and CS segments. • The addition of minor GO can improve the electrochemical activity of the neat CS. - Abstract: A series of chitosan (CS) nanocomposites incorporated with graphene oxide (GO) nanosheets were facilely prepared by sonochemical method. Characterized by scanning electron microscopy, the obtained nanocomposites showed fine dispersion of GO in the CS matrix. Meanwhile, a marked interfacial interaction was also revealed as the values of glass transition temperature, the decomposition temperature and the storage modulus were significantly increased with the addition of GO. Furthermore, the well dispersed GO nanosheets could significantly improve the electrochemical activity of the CS as demonstrated by the electrochemical behaviors of pure CS and the GO/CS composite electrodes. Hence, the GO/CS nanocomposites film could be a promising candidate in the fabrication of electrochemical biosensors

  15. Electrochemical oxidation of organic carbonate based electrolyte solutions at lithium metal oxide electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Imhof, R; Novak, P [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1999-08-01

    The oxidative decomposition of carbonate based electrolyte solutions at practical lithium metal oxide composite electrodes was studied by differential electrochemical mass spectrometry. For propylene carbonate (PC), CO{sub 2} evolution was detected at LiNiO{sub 2}, LiCoO{sub 2}, and LiMn{sub 2}O{sub 4} composite electrodes. The starting point of gas evolution was 4.2 V vs. Li/Li{sup +} at LiNiO{sub 2}, whereas at LiCoO{sub 2} and LiMn{sub 2}O{sub 4}, CO{sub 2} evolution was only observed above 4.8 V vs. Li/Li{sup +}. In addition, various other volatile electrolyte decomposition products of PC were detected when using LiCoO{sub 2}, LiMn{sub 2}O4, and carbon black electrodes. In ethylene carbonate / dimethyl carbonate, CO{sub 2} evolution was only detected at LiNiO{sub 2} electrodes, again starting at about 4.2 V vs. Li/Li{sup +}. (author) 3 figs., 2 refs.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-01-06

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

  17. Recent advances in electrochemical biosensors based on graphene two-dimensional nanomaterials.

    Science.gov (United States)

    Song, Yang; Luo, Yanan; Zhu, Chengzhou; Li, He; Du, Dan; Lin, Yuehe

    2016-02-15

    Graphene as a star among two-dimensional nanomaterials has attracted tremendous research interest in the field of electrochemistry due to their intrinsic properties, including the electronic, optical, and mechanical properties associated with their planar structure. The marriage of graphene and electrochemical biosensors has created many ingenious biosensing strategies for applications in the areas of clinical diagnosis and food safety. This review provides a comprehensive overview of the recent advances in the development of graphene based electrochemical biosensors. Special attention is paid to graphene-based enzyme biosensors, immunosensors, and DNA biosensors. Future perspectives on high-performance graphene-based electrochemical biosensors are also discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Advances in electrospun carbon fiber-based electrochemical sensing platforms for bioanalytical applications.

    Science.gov (United States)

    Mao, Xianwen; Tian, Wenda; Hatton, T Alan; Rutledge, Gregory C

    2016-02-01

    Electrochemical sensing is an efficient and inexpensive method for detection of a range of chemicals of biological, clinical, and environmental interest. Carbon materials-based electrodes are commonly employed for the development of electrochemical sensors because of their low cost, biocompatibility, and facile electron transfer kinetics. Electrospun carbon fibers (ECFs), prepared by electrospinning of a polymeric precursor and subsequent thermal treatment, have emerged as promising carbon systems for biosensing applications since the electrochemical properties of these carbon fibers can be easily modified by processing conditions and post-treatment. This review addresses recent progress in the use of ECFs for sensor fabrication and analyte detection. We focus on the modification strategies of ECFs and identification of the key components that impart the bioelectroanalytical activities, and point out the future challenges that must be addressed in order to advance the fundamental understanding of the ECF electrochemistry and to realize the practical applications of ECF-based sensing devices.

  19. Aluminum Oxide Formation On Fecral Catalyst Support By Electro-Chemical Coating

    Directory of Open Access Journals (Sweden)

    Yang H.S.

    2015-06-01

    Full Text Available FeCrAl is comprised essentially of Fe, Cr, Al and generally considered as metallic substrates for catalyst support because of its advantage in the high-temperature corrosion resistance, high mechanical strength, and ductility. Oxidation film and its adhesion on FeCrAl surface with aluminum are important for catalyst life. Therefore various appropriate surface treatments such as thermal oxidation, Sol, PVD, CVD has studied. In this research, PEO (plasma electrolytic oxidation process was applied to form the aluminum oxide on FeCrAl surface, and the formed oxide particle according to process conditions such as electric energy and oxidation time were investigated. Microstructure and aluminum oxide particle on FeCrAl surface after PEO process was observed by FE-SEM and EDS with element mapping analysis. The study presents possibility of aluminum oxide formation by electro-chemical coating process without any pretreatment of FeCrAl.

  20. Chemically grown, porous, nickel oxide thin-film for electrochemical supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Inamdar, A.I.; Kim, YoungSam; Im, Hyunsik [Department of Semiconductor Science, Dongguk University, Seoul 100-715 (Korea, Republic of); Pawar, S.M.; Kim, J.H. [Department of Materials Science and Engineering, Chonnam National University, Gwangju 500-757 (Korea, Republic of); Kim, Hyungsang [Department of Physics, Dongguk University, Seoul 100-715 (Korea, Republic of)

    2011-02-15

    A porous nickel oxide film is successfully synthesized by means of a chemical bath deposition technique from an aqueous nickel nitrate solution. The formation of a rock salt NiO structure is confirmed with XRD measurements. The electrochemical supercapacitor properties of the nickel oxide film are examined using cyclic voltammetery (CV), galvanostatic and impedance measurements in two different electrolytes, namely, NaOH and KOH. A specific capacitance of {proportional_to}129.5 F g{sup -1} in the NaOH electrolyte and {proportional_to}69.8 F g{sup -1} in the KOH electrolyte is obtained from a cyclic voltammetery study. The electrochemical stability of the NiO electrode is observed for 1500 charge-discharge cycles. The capacitative behaviour of the NiO electrode is confirmed from electrochemical impedance measurements. (author)

  1. Effects of Salts and Metal Oxides on Electrochemical and Optical Properties of Streptococcus mutans

    Science.gov (United States)

    Kawai, Tsuyoshi; Nagame, Seigo; Kambara, Masaki; Yoshino, Katsumi

    1994-10-01

    The effects of calcium salts and metal oxide powders on electrochemical, optical and biological properties of Streptococcus mutans have been studied as a novel method to determine the strain. Electrochemical signals of Streptococcus mutans show remarkable decrease in the presence of saturated calcium salts such as CaHPO4, Ca3(PO4)2, and Ca5(PO4)3OH depending on the strains of Streptococcus mutans: Ingbritt, NCTC-10449, or GS-5. The number of viable cells also decreases upon addition of these powders. The effects of metal oxides such as ZnO and BaTiO3 on the electrochemical characteristics and photoluminescence of Streptococcus mutans have also been studied.

  2. Optical and structural properties of porous zinc oxide fabricated via electrochemical etching method

    International Nuclear Information System (INIS)

    Ching, C.G.; Lee, S.C.; Ooi, P.K.; Ng, S.S.; Hassan, Z.; Hassan, H. Abu; Abdullah, M.J.

    2013-01-01

    Highlights: • Hillock like porous structure zinc oxide was obtained via electrochemical etching. • Anisotropic dominance etching process by KOH etchant. • Reststrahlen features are sensitive to multilayer porous structure. • Determination of porosity from IR reflectance spectrum. -- Abstract: We investigated the optical and structural properties of porous zinc oxide (ZnO) thin film fabricated by ultraviolet light-assisted electrochemical etching. This fabrication process used 10 wt% potassium hydroxide solution as an electrolyte. Hillock-like porous ZnO films were successfully fabricated according to the field emission scanning electron microscopy results. The cross-sectional study of the sample indicated that anisotropic-dominated etching process occurred. However, the atomic force microscopic results showed an increase in surface roughness of the sample after electrochemical etching. A resonance hump induced by the porous structure was observed in the infrared reflectance spectrum. Using theoretical modeling technique, ZnO porosification was verified, and the porosity of the sample was determined

  3. Multilayered films of cobalt oxyhydroxide nanowires/manganese oxide nanosheets for electrochemical capacitor

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Huajun [State Key Laboratory Breeding Base of Green Chemistry Synthesis Technology, Zhejiang University of Technology, Hangzhou 310014 (China); ARC Centre of Excellence for Functional Nanomaterials, School of Chemical Engineering and AIBN, The University of Queensland, St Lucia, Brisbane, QLD 4072 (Australia); Tang, Fengqiu; Mukherji, Aniruddh; Yan, Xiaoxia; Wang, Lianzhou (Max) Lu, Gao Qing [ARC Centre of Excellence for Functional Nanomaterials, School of Chemical Engineering and AIBN, The University of Queensland, St Lucia, Brisbane, QLD 4072 (Australia); Lim, Melvin [Division of Environmental and Water Resources Engineering, School of Civil and Environmental Engineering, Nanyang Technological University, 639798 (Singapore)

    2010-01-15

    Multilayered films of cobalt oxyhydroxide nanowires (CoOOHNW) and exfoliated manganese oxide nanosheet (MONS) are fabricated by potentiostatic deposition and electrostatic self-assembly on indium-tin oxide coated glass substrates. The morphology and chemical composition of these films are characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectra (XPS) and the potential application as electrochemical supercapacitors are investigated using cyclic voltammetry and charge-discharge measurements. These ITO/CoOOHNW/MONS multilayered film electrodes exhibit excellent electrochemical capacitance properties, including high specific capacitance (507 F g{sup -1}) and long cycling durability (less 2% capacity loss after 5000 charge/discharge cycles). These characteristics indicate that these newly developed films may find important application for electrochemical capacitors. (author)

  4. Nickel oxide/hydroxide nanoplatelets synthesized by chemical precipitation for electrochemical capacitors

    International Nuclear Information System (INIS)

    Wu, M.-S.; Hsieh, H.-H.

    2008-01-01

    Nickel hydroxide powder prepared by directly chemical precipitation method at room temperature has a nanoplatelet-like morphology and could be converted into nickel oxide at annealing temperature higher than 300 deg. C, confirmed by the thermal gravimetric analysis and X-ray diffraction. Annealing temperature influences significantly both the electrical conductivity and the specific surface area of nickel oxide/hydroxide powder, and consequently determines the capacitor behavior. Electrochemical capacitive behavior of the synthesized nickel hydroxide/oxide film is investigated by cyclic voltammetry and electrochemical impedance spectroscope methods. After 300 deg. C annealing, the highest specific capacitance of 108 F g -1 is obtained at scan rate of 10 mV s -1 . When annealing temperature is lower than 300 deg. C, the electrical conductivity of nickel hydroxide dominates primarily the capacitive behavior. When annealing temperature is higher than 300 deg. C, both electrical conductivity and specific surface area of the nickel oxide dominate the capacitive behavior

  5. Boron-Doped Diamond Electrodes for the Electrochemical Oxidation and Cleavage of Peptides

    NARCIS (Netherlands)

    Roeser, Julien; Alting, Niels F. A.; Permentier, Hjalmar P.; Bruins, Andries P.; Bischoff, Rainer

    2013-01-01

    Electrochemical oxidation of peptides and proteins is traditionally performed on carbon-based electrodes. Adsorption caused by the affinity of hydrophobic and aromatic amino acids toward these surfaces leads to electrode fouling. We compared the performance of boron-doped diamond (BDD) and glassy

  6. High-performance symmetric electrochemical capacitor based on graphene foam and nanostructured manganese oxide

    CSIR Research Space (South Africa)

    Bello, A

    2013-01-01

    Full Text Available We have fabricated a symmetric electrochemical capacitor with high energy and power densities based on a composite of graphene foam (GF) with 80 wt% of manganese oxide (MnO(sub2)) deposited by hydrothermal synthesis. Raman spectroscopy and X...

  7. Microwave synthesis of metal nanocatalysts for the electrochemical oxidation of small biomolecules

    DEFF Research Database (Denmark)

    Jensen, Kathrine Schiørring Steen; Sun, Hongyu; Werchmeister, Rebecka Maria Larsen

    2017-01-01

    Electrochemical oxidation of small biomolecules provides an approach to generate clean energy from a sustainable resource. It serves as a principle for anode reactions in fuel cells to convert energy stored in chemical bonds into electrical power. Efficient and robust nanocatalysts are essential ...

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

    Science.gov (United States)

    Siriviriyanun, Ampornphan; Imae, Toyoko

    2013-04-14

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

  9. Electrochemical stability and transformations of fluorinated poly(2,6-dimethyl-1,4-phenylene oxide)

    NARCIS (Netherlands)

    Pud, A.A.; Rogalsky, S.P.; Ghapoval, G.S.; Kharitonov, A.P.; Kemperman, Antonius J.B.

    2000-01-01

    Fluorination of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) leads to narrowing of its window of electrochemical stability in a cathodic range of potentials. It is found this is connected with appearance of both perfluorinated and incompletely fluorinated units in the polymer. The former units are

  10. Novel Insights into the Electrochemical Detection of Nitric Oxide in Biological Systems

    Czech Academy of Sciences Publication Activity Database

    Pekarová, Michaela; Lojek, Antonín; Hrbáč, J.; Kuchta, R.; Kadlec, J.; Kubala, Lukáš

    2014-01-01

    Roč. 60, č. 1 (2014), s. 8-12 ISSN 0015-5500 R&D Projects: GA MŠk(CZ) EE2.3.30.0030; GA ČR(CZ) GP13-40882P Institutional support: RVO:68081707 Keywords : nitric oxide * electrochemical detector * biological systems Subject RIV: BO - Biophysics Impact factor: 1.000, year: 2014

  11. Continuous electrochemical oxidation of biomass derived 5-(hydroxymethyl)furfural into 2,5-furandicarboxylic acid

    NARCIS (Netherlands)

    Latsuzbaia, R.; Bisselink, R.; Anastasopol, A.; Meer, van der H.; Heck, van R.; Yagüe, M.S.; Zijlstra, M.; Roelands, M.; Crockatt, M.; Goetheer, E.; Giling, E.

    2018-01-01

    Abstract: A continuous electrochemical process with integrated product separation has been developed for production of 2,5-furandicarboxylic acid (FDCA) by oxidation of 5-(hydroxymethyl)furfural (HMF) in aqueous alkaline media on non-noble Ni/NiOOH foam electrodes at ambient conditions. Initially,

  12. Electrochemical fabrication of CdS/Co nanowire arrays in porous aluminum oxide templates

    CERN Document Server

    Yoon, C H

    2002-01-01

    A procedure for preparing semiconductor/metal nanowire arrays is described, based on a template method which entails electrochemical deposition into nanometer-wide parallel pores of anodic aluminum oxide films on aluminum. Aligned CdS/Co heterostructured nanowires have been prepared by ac electrodeposition in the anodic aluminum oxide templates. By varying the preparation conditions, a variety of CdS/Co nanowire arrays were fabricated, whose dimensional properties could be adjusted.

  13. Chitosan-iron oxide nanocomposite based electrochemical aptasensor for determination of malathion

    Energy Technology Data Exchange (ETDEWEB)

    Prabhakar, Nirmal, E-mail: nirmalprabhakar@gmail.com; Thakur, Himkusha; Bharti, Anu; Kaur, Navpreet

    2016-10-05

    An electrochemical aptasensor based on chitosan-iron oxide nanocomposite (CHIT-IO) film deposited on fluorine tin Oxide (FTO) was developed for the detection of malathion. Iron oxide nanoparticles were prepared by co-precipitation method and characterized by Transmission electron microscopy and UV–Visible spectroscopy. The biotinylated DNA aptamer sequence specific to the malathion was immobilized onto the iron oxide doped-chitosan/FTO electrode by using streptavidin as linking molecule. Various characterization studies like Field Emission-Scanning Electron Microscopy (FE-SEM), Fourier Transform Infrared Spectroscopy (FT-IR), and Electrochemical studies were performed to attest the successful fabrication of bioelectrodes. Experimental parameters like aptamer concentration, response time, stability of electrode and reusability studies were optimized. Aptamer immobilized chitosan-iron oxide nanocomposite (APT/SA/CHIT-IO/FTO) bioelectrodes exhibited LOD of about 0.001 ng/mL within 15 min and spike-in studies revealed about 80–92% recovery of malathion from the lettuce leaves and soil sample. - Highlights: • An electrochemical aptasensor for the detection of Malathion has been developed. • Chitosan-iron oxide NP deposited FTO sheets provides platform for aptamer immobilization. • Aptasensor has efficiency to detect malathion upto 0.001 ng/mL within 15 min.

  14. Comparative study of electrochemical oxidation of herbicide 2,4,5-T: Kinetics, parametric optimization and mineralization pathway

    Directory of Open Access Journals (Sweden)

    Hicham Zazou

    2017-01-01

    Full Text Available Oxidative degradation of herbicide 2,4,5-T was studied by electrochemical advanced oxidation processes anodic oxidation and electro-Fenton (EF using Pt/carbon felt and BDD/carbon felt cells. The effect of main operating parameters on oxidation of 2,4,5-T and mineralization of its aqueous solution were investigated. The rate constant for oxidation of 2,4,5-T by ·≡OH was determined as (3.7 ± 0.2 × 109 M−1 s−1 using competition kinetics method. The EF process with BDD anode was shown to be very efficient reaching 94% mineralization in 3 h treatment. Based on identified aromatic intermediates, short-chain carboxylic acids, released inorganic ions and total organic carbon removal measurements, a plausible oxidation pathway for mineralization of 2,4,5-T by hydroxyl radical was proposed. In addition, the evolution of solution toxicity during treatment was monitored by Microtox method showing the formation of toxic aromatic/cyclic intermediates. The results showed also that EF process was able to remove efficiently toxic intermediates and consequently solution toxicity.

  15. Electrochemically active microorganisms from an acid mine drainage-affected site promote cathode oxidation in microbial fuel cells

    KAUST Repository

    Rojas, Claudia; Vargas, Ignacio T.; Bruns, Mary Ann; Regan, John M.

    2017-01-01

    The limited database of acidophilic or acidotolerant electrochemically active microorganisms prevents advancements on microbial fuel cells (MFCs) operated under low pH. In this study, three MFCs were used to enrich cathodic biofilms using acid mine drainage (AMD) sediments as inoculum. Linear sweep voltammetry showed cathodic current plateaus of 5.5 (± 0.7) mA at about − 170 mV vs Ag/AgCl and 8.5 (± 0.9) mA between − 500 mV to − 450 mV vs Ag/AgCl for biofilms developed on small graphite fiber brushes. After gamma irradiation, biocathodes exhibited a decrease in current density approaching that of abiotic controls. Electrochemical impedance spectroscopy showed six-fold lower charge transfer resistance with viable biofilm. Pyrosequencing data showed that Proteobacteria and Firmicutes dominated the biofilms. Acidithiobacillus representatives were enriched in some biocathodes, supporting the potential importance of these known iron and sulfur oxidizers as cathodic biocatalysts. Other acidophilic chemolithoautotrophs identified included Sulfobacillus and Leptospirillum species. The presence of chemoautotrophs was consistent with functional capabilities predicted by PICRUSt related to carbon fixation pathways in prokaryotic microorganisms. Acidophilic or acidotolerant heterotrophs were also abundant; however, their contribution to cathodic performance is unknown. This study directs subsequent research efforts to particular groups of AMD-associated bacteria that are electrochemically active on cathodes.

  16. Electrochemically active microorganisms from an acid mine drainage-affected site promote cathode oxidation in microbial fuel cells

    KAUST Repository

    Rojas, Claudia

    2017-08-03

    The limited database of acidophilic or acidotolerant electrochemically active microorganisms prevents advancements on microbial fuel cells (MFCs) operated under low pH. In this study, three MFCs were used to enrich cathodic biofilms using acid mine drainage (AMD) sediments as inoculum. Linear sweep voltammetry showed cathodic current plateaus of 5.5 (± 0.7) mA at about − 170 mV vs Ag/AgCl and 8.5 (± 0.9) mA between − 500 mV to − 450 mV vs Ag/AgCl for biofilms developed on small graphite fiber brushes. After gamma irradiation, biocathodes exhibited a decrease in current density approaching that of abiotic controls. Electrochemical impedance spectroscopy showed six-fold lower charge transfer resistance with viable biofilm. Pyrosequencing data showed that Proteobacteria and Firmicutes dominated the biofilms. Acidithiobacillus representatives were enriched in some biocathodes, supporting the potential importance of these known iron and sulfur oxidizers as cathodic biocatalysts. Other acidophilic chemolithoautotrophs identified included Sulfobacillus and Leptospirillum species. The presence of chemoautotrophs was consistent with functional capabilities predicted by PICRUSt related to carbon fixation pathways in prokaryotic microorganisms. Acidophilic or acidotolerant heterotrophs were also abundant; however, their contribution to cathodic performance is unknown. This study directs subsequent research efforts to particular groups of AMD-associated bacteria that are electrochemically active on cathodes.

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

    Science.gov (United States)

    Radoń, Adrian; Włodarczyk, Patryk; Łukowiec, Dariusz

    2018-05-01

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

  18. Boron-doped diamond electrodes for the electrochemical oxidation and cleavage of peptides.

    Science.gov (United States)

    Roeser, Julien; Alting, Niels F A; Permentier, Hjalmar P; Bruins, Andries P; Bischoff, Rainer

    2013-07-16

    Electrochemical oxidation of peptides and proteins is traditionally performed on carbon-based electrodes. Adsorption caused by the affinity of hydrophobic and aromatic amino acids toward these surfaces leads to electrode fouling. We compared the performance of boron-doped diamond (BDD) and glassy carbon (GC) electrodes for the electrochemical oxidation and cleavage of peptides. An optimal working potential of 2000 mV was chosen to ensure oxidation of peptides on BDD by electron transfer processes only. Oxidation by electrogenerated OH radicals took place above 2500 mV on BDD, which is undesirable if cleavage of a peptide is to be achieved. BDD showed improved cleavage yield and reduced adsorption for a set of small peptides, some of which had been previously shown to undergo electrochemical cleavage C-terminal to tyrosine (Tyr) and tryptophan (Trp) on porous carbon electrodes. Repeated oxidation with BDD electrodes resulted in progressively lower conversion yields due to a change in surface termination. Cathodic pretreatment of BDD at a negative potential in an acidic environment successfully regenerated the electrode surface and allowed for repeatable reactions over extended periods of time. BDD electrodes are a promising alternative to GC electrodes in terms of reduced adsorption and fouling and the possibility to regenerate them for consistent high-yield electrochemical cleavage of peptides. The fact that OH-radicals can be produced by anodic oxidation of water at elevated positive potentials is an additional advantage as they allow another set of oxidative reactions in analogy to the Fenton reaction, thus widening the scope of electrochemistry in protein and peptide chemistry and analytics.

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

    Science.gov (United States)

    Babakhani, Banafsheh

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

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

    Science.gov (United States)

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

    2010-07-20

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

  1. Electrochemical reduction of cerium oxides in molten salts

    International Nuclear Information System (INIS)

    Claux, B.; Serp, J.; Fouletier, J.

    2011-01-01

    This brief article describes a pyrochemical process that is used by CEA to turn actinide oxides into metal actinides. This process is applied to Cerium oxides (CeO 2 ) that simulate actinide oxides well chemically as cerium belongs to the lanthanide family. The process is in fact an electrolysis of cerium oxide in a bath of molten calcium chloride salt whose temperature is between 800 and 900 Celsius degrees. At those temperatures calcium chloride becomes a ionic liquid (Ca 2+ and Cl - ) that is a good electrical conductor and is particularly well-adapted as solvent to an electrolytic process. The electrolysis current allows the transformation of solvent Ca 2+ ions into metal calcium which, in turn, can reduce cerium oxide into metal cerium through chromatically. Experimental data shows the reduction of up to 90% of 10 g samples of CeO 2 in a 6 hour long electrolysis while the best reduction rate ever known was 80% so far. This result is all the more promising that cerium oxides are more difficult to reduce than actinide oxides from the thermodynamical perspective

  2. Modified cermet fuel electrodes for solid oxide electrochemical cells

    Science.gov (United States)

    Ruka, Roswell J.; Spengler, Charles J.

    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.

  3. Theoretical investigation of the activity of cobalt oxides for the electrochemical oxidation of water.

    Science.gov (United States)

    Bajdich, Michal; García-Mota, Mónica; Vojvodic, Aleksandra; Nørskov, Jens K; Bell, Alexis T

    2013-09-11

    The presence of layered cobalt oxides has been identified experimentally in Co-based anodes under oxygen-evolving conditions. In this work, we report the results of theoretical investigations of the relative stability of layered and spinel bulk phases of Co oxides, as well as the stability of selected surfaces as a function of applied potential and pH. We then study the oxygen evolution reaction (OER) on these surfaces and obtain activity trends at experimentally relevant electro-chemical conditions. Our calculated volume Pourbaix diagram shows that β-CoOOH is the active phase where the OER occurs in alkaline media. We calculate relative surface stabilities and adsorbate coverages of the most stable low-index surfaces of β-CoOOH: (0001), (0112), and (1014). We find that at low applied potentials, the (1014) surface is the most stable, while the (0112) surface is the more stable at higher potentials. Next, we compare the theoretical overpotentials for all three surfaces and find that the (1014) surface is the most active one as characterized by an overpotential of η = 0.48 V. The high activity of the (1014) surface can be attributed to the observation that the resting state of Co in the active site is Co(3+) during the OER, whereas Co is in the Co(4+) state in the less active surfaces. Lastly, we demonstrate that the overpotential of the (1014) surface can be lowered further by surface substitution of Co by Ni. This finding could explain the experimentally observed enhancement in the OER activity of Ni(y)Co(1-y)O(x) thin films with increasing Ni content. All energetics in this work were obtained from density functional theory using the Hubbard-U correction.

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

    Science.gov (United States)

    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.

  5. Synthesis of binary bismuth-cadmium oxide nanorods with sensitive electrochemical sensing performance

    International Nuclear Information System (INIS)

    Wen, Yong; Pei, Lizhai; Wei, Tian

    2017-01-01

    Binary bismuth-cadmium oxide nanorods have been synthesized by a simple hydrothermal process without templates and additives. X-ray diffraction and high-resolution transmission electron microscopy reveal that the nanorods possess single crystalline tetragonal Bi 2 CdO 4 phase. Scanning electron microscopy and transmission electron microscopy images show that the length and diameter of the nanorods are 20-300 nm and 5-10 μm, respectively. The formation of the binary bismuth-cadmium oxide nanorods is closely related to the hydrothermal parameters. The electrochemical sensing performance of the binary bismuth-cadmium oxide nanorods has been investigated using the nanorods as glassy carbon electrode modifiers. The detection limit is 0.19 μM with a linear range of 0.0005-2 mM. The nanorod-modified glassy carbon electrode exhibits good electrocatalytic activity toward L-cysteine and great application potential for electrochemical sensors.

  6. Electrochemical and theoretical characterization of the electro-oxidation of dimethoxycurcumin

    Science.gov (United States)

    Arrue, Lily; Barra, Tomas; Camarada, María Belén; Zarate, Ximena; Schott, Eduardo

    2017-06-01

    Dimethoxycurcumin (DMC) ((1E,6E)-1-(3,4-dimethoxycyclohexyl)-7-(3,4-dimethoxyphenyl) hepta-1,6- diene-3,5-dione) is a natural polyphenolic compound that appears together with curcumin in turmeric. Both molecules have wide range biological activities as antioxidant, anti-inflammatory and anti-carcinogenic agent. To evaluate the oxidation process and kinetics for DMC, the rate constant, electron transfer and diffusion coefficients for the electrochemical oxidation were determined. Therefore, its electrochemical behavior over a platinum electrode in anhydrous media was investigated. Furthermore, DFT calculations were performed to give a rational explanation to the obtained results. All the results support the fact that the central sbnd CH2sbnd group is the most reactive against an oxidation process.

  7. Synthesis of binary bismuth-cadmium oxide nanorods with sensitive electrochemical sensing performance

    Energy Technology Data Exchange (ETDEWEB)

    Wen, Yong [Xinjiang Univ., Xinjiang (China). School of Civil Engineering and Architecture; Pei, Lizhai; Wei, Tian [Anhui Univ. of Technology, Anhui (China). School of Materials Science and Engineering

    2017-07-15

    Binary bismuth-cadmium oxide nanorods have been synthesized by a simple hydrothermal process without templates and additives. X-ray diffraction and high-resolution transmission electron microscopy reveal that the nanorods possess single crystalline tetragonal Bi{sub 2}CdO{sub 4} phase. Scanning electron microscopy and transmission electron microscopy images show that the length and diameter of the nanorods are 20-300 nm and 5-10 μm, respectively. The formation of the binary bismuth-cadmium oxide nanorods is closely related to the hydrothermal parameters. The electrochemical sensing performance of the binary bismuth-cadmium oxide nanorods has been investigated using the nanorods as glassy carbon electrode modifiers. The detection limit is 0.19 μM with a linear range of 0.0005-2 mM. The nanorod-modified glassy carbon electrode exhibits good electrocatalytic activity toward L-cysteine and great application potential for electrochemical sensors.

  8. Structural, electrical, and electrochemical characterization of Ni--Pr oxide thick films

    Energy Technology Data Exchange (ETDEWEB)

    Mari, C; Scolari, V; Fiori, G; Pizzini, S

    1977-03-01

    Oxides with metallic conductivity could and have been used instead of noble metals as insert electrodes in aqueous solutions as well as electrodes for high temperature fuel cells and electrolyzers and as catalysts for the conversion of exhaust gases from internal combustion engines. The aim of this paper is to report the results of a physico-chemical characterization (structure, morphology, electrochemical behavior) of Ni--Pr oxides which have been proposed as electrode materials for high temperature fuel cells. The electrochemical characterization was carried out in aqueous solutions at room temperature and with solid electrolytes at high temperature. Evidence has been found in the former case for an oxide electrode type of behavior. In the high temperature case, very low overvoltage values have been observed during cathodic oxygen reduction, while the electrode undergoes a reaction with oxygen during anodic oxygen evolution.

  9. Electrochemical Oxidation of Phenol using a Flow-through Micro ...

    African Journals Online (AJOL)

    NICO

    plate automotive type and the industrial tubular electrode either by dry oxide or .... HPLC pump that allowed careful control of the flow of solutions containing the ... chromatographic separation was done using a Waters micro. RESEARCH ...

  10. Polyaniline-grafted reduced graphene oxide for efficient electrochemical supercapacitors.

    Science.gov (United States)

    Kumar, Nanjundan Ashok; Choi, Hyun-Jung; Shin, Yeon Ran; Chang, Dong Wook; Dai, Liming; Baek, Jong-Beom

    2012-02-28

    An alternative and effective route to prepare conducting polyaniline-grafted reduced graphene oxide (PANi-g-rGO) composite with highly enhanced properties is reported. In order to prepare PANi-g-rGO, amine-protected 4-aminophenol was initially grafted to graphite oxide (GO) via acyl chemistry where a concomitant partial reduction of GO occurred due to the refluxing and exposure of GO to thionyl chloride vapors and heating. Following the deprotection of amine groups, an in situ chemical oxidative grafting of aniline in the presence of an oxidizing agent was carried out to yield highly conducting PANi-g-rGO. Electron microscopic studies demonstrated that the resultant composite has fibrillar morphology with a room-temperature electrical conductivity as high as 8.66 S/cm and capacitance of 250 F/g with good cycling stability.

  11. Electrochemical Water-Splitting Based on Hypochlorite Oxidation

    Czech Academy of Sciences Publication Activity Database

    Minhová Macounová, Kateřina; Simic, N.; Ahlberg, E.; Krtil, Petr

    2015-01-01

    Roč. 137, č. 23 (2015), s. 7262-7265 ISSN 0002-7863 Institutional support: RVO:61388955 Keywords : electrochemistry * hypochlorite oxidation * water-splitting Subject RIV: CG - Electrochemistry Impact factor: 13.038, year: 2015

  12. Coating of tips for electrochemical scanning tunneling microscopy by means of silicon, magnesium, and tungsten oxides

    Science.gov (United States)

    Salerno, Marco

    2010-09-01

    Different combinations of metal tips and oxide coatings have been tested for possible operation in electrochemical scanning tunneling microscopy. Silicon and magnesium oxides have been thermally evaporated onto gold and platinum-iridium tips, respectively. Two different thickness values have been explored for both materials, namely, 40 and 120 nm for silicon oxide and 20 and 60 nm for magnesium oxide. Alternatively, tungsten oxide has been grown on tungsten tips via electrochemical anodization. In the latter case, to seek optimal results we have varied the pH of the anodizing electrolyte between one and four. The oxide coated tips have been first inspected by means of scanning electron microscopy equipped with microanalysis to determine the morphological results of the coating. Second, the coated tips have been electrically characterized ex situ for stability in time by means of cyclic voltammetry in 1 M aqueous KCl supporting electrolyte, both bare and supplemented with K3[Fe(CN)6] complex at 10 mM concentration in milliQ water as an analyte. Only the tungsten oxide coated tungsten tips have shown stable electrical behavior in the electrolyte. For these tips, the uncoated metal area has been estimated from the electrical current levels, and they have been successfully tested by imaging a gold grating in situ, which provided stable results for several hours. The successful tungsten oxide coating obtained at pH=4 has been assigned to the WO3 form.

  13. Surface properties of nanostructured NiO undergoing electrochemical oxidation in 3-methoxy-propionitrile

    Science.gov (United States)

    Bonomo, Matteo; Marrani, Andrea Giacomo; Novelli, Vittoria; Awais, Muhammad; Dowling, Denis P.; Vos, Johannes G.; Dini, Danilo

    2017-05-01

    Nanostructured nickel oxide (NiO) was deposited in the configuration of thin film (thickness, l = 2-6 μm) onto fluorine-doped tin oxide (FTO) substrates via plasma-assisted rapid discharge sintering (RDS). Electrochemical cycling of RDS NiO in 3-methoxy-propionitrile (3-MPN) revealed two characteristic peaks of NiO oxidation which were associated to the surface-confined redox processes Ni(II) → Ni(III) and Ni(III) → Ni(IV). Grazing angle X-ray photoelectron spectroscopy (XPS) was conducted ex-situ on NiO electrodes in both pristine and oxidized states. Oxidized NiO samples for XPS experiments were obtained in the potentiostatic mode through the polarization of NiO at its two characteristic potentials of oxidation. The XPS analysis allowed to ascertain the electronic structure of the nanoporous NiO framework, and verify the adsorption of perchlorate and chloride anions onto NiO surface due to the compensation of the charge stored in oxidized NiO. XPS also revealed that the spectrum within the region characteristic of Ni 2p ionization does not vary considerably with the state of charge of the nickel centres. This finding is in evident contrast to what has been observed for the same system when it undergoes electrochemical oxidation in aqueous electrolyte.

  14. Electrochemical Properties of Graphene-vanadium Oxide Composite Prepared by Electro-deposition for Electrochemical Capacitors

    International Nuclear Information System (INIS)

    Jeong, Heeyoung; Jeong, Sang Mun

    2015-01-01

    The nanostructural graphene/vanadium oxide (graphene/V 2 O 5 ) composite with enhanced capacitance was synthesized by the electro-deposition in 0.5 M VOSO 4 solution. The morphology of composites was characterized using scanning electron microscopy (SEM), x-ray diffraction pattern (XRD), and x-ray photoelectron spectroscopy (XPS). The oxidation states of the electro-deposited vanadium oxide was found to be V 5+ and V 4+ . The morphology of the prepared graphene/V 2 O 5 composite exhibits a netlike nano-structure with V 2 O 5 nanorods in about 100 nm diameter, which could lead a better contact between electrolyte an electrode. The composite with a deposition time of 4,000 s exhibits the specific capacitance of 854 mF/cm 2 at a scan rate of 20 mV/s and the capacitance retention of 53% after 1000 CV cycles

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

    International Nuclear Information System (INIS)

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

    2014-01-01

    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 μM with a low detection limit of 0.01 μM (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. - Highlights: • The 4-ABA/ERGO/GCE was fabricated by a two-step electrochemical method. • Electrochemical behavior of acetaminophen at the 4-ABA/ERGO/GCE was investigated. • The electrochemical sensor exhibited a low detection limit and good selectivity. • This sensor was applied to the detection of acetaminophen in commercial tablets

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

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Wencai [Key Laboratory for Colloid and Interface Chemistry of State Education Ministry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); School of Chemistry and Chemical Engineering, Qilu Normal University, Jinan 250013 (China); Huang, Hui; Gao, Xiaochun [Key Laboratory for Colloid and Interface Chemistry of State Education Ministry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China); Ma, Houyi, E-mail: hyma@sdu.edu.cn [Key Laboratory for Colloid and Interface Chemistry of State Education Ministry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100 (China)

    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 μM with a low detection limit of 0.01 μM (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. - Highlights: • The 4-ABA/ERGO/GCE was fabricated by a two-step electrochemical method. • Electrochemical behavior of acetaminophen at the 4-ABA/ERGO/GCE was investigated. • The electrochemical sensor exhibited a low detection limit and good selectivity. • This sensor was applied to the detection of acetaminophen in commercial tablets.

  17. Effect of graphene oxide nanoplatelets on electrochemical properties of steel substrate in saline media

    International Nuclear Information System (INIS)

    Chaudhry, A.U.; Mittal, Vikas; Mishra, Brajendra

    2015-01-01

    There has been increased interest in using graphene oxide (GO) in various industrial applications such as working fluids, lubricants, oil and gas fields, heavy metal removal from water, anticorrosion paints and coatings etc. We studied electrochemical properties of steel in the presence of suspended GO in saline media. GO suspension has been characterized using Transmission electron microscopy (TEM) and X-ray diffractometer (XRD). We measured the effect of the GO concentration (0–15 ppm) on electrochemical properties of steel using different techniques: open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) and potentiodynamic (PD) methods. Results indicate that the suppression of corrosion is directly proportional to increasing GO concentrations in saline environments. Surface morphology of corroded samples was examined using Scanning Electron Microscopy (SEM). Identification of the elements at accumulated layer was estimated from peaks of energy dispersive x-ray spectroscopy (EDX) and XRD. Increased protection abilities with increasing GO concentration have been attributed to the domination of salt layer presence at the surface of steel which occurs via precipitation of sodium chloride. Surface analysis confirm that there is no direct effect of GO on the protection behavior of steel. The presence of GO in the solution can enhance the precipitation of NaCl due to the decreased solubility NaCl which further slows down the corrosion. The pourbaix diagram shows that GO forms an anionic compound with sodium which may enhance the precipitation at working electrode. - Graphical abstract: Display Omitted - Highlights: • Electrochemical properties of steel in saline media containing nano graphene oxide. • Effect of concentration of graphene oxide on electrochemical properties. • Mechanism of corrosion reduction due to the presence of graphene oxide

  18. Electrochemical oxidation of biological pretreated and membrane separated landfill leachate concentrates on boron doped diamond anode

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Bo, E-mail: 357436235@qq.com [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Yu, Zhiming, E-mail: zhiming@csu.edu.cn [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Wei, Qiuping, E-mail: qiupwei@csu.edu.cn [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Long, HangYu, E-mail: 55686385@qq.com [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Xie, Youneng, E-mail: 1187272844@qq.com [School of Materials Science and Engineering, Central South University, Changsha 410083 (China); Wang, Yijia, E-mail: 503630433@qq.com [School of Materials Science and Engineering, Central South University, Changsha 410083 (China)

    2016-07-30

    Highlights: • High quality boron-doped diamond film electrodes were synthesized on Nb substrates. • Electrochemical oxidation on boron-doped diamond anode is an effective method for treating landfill leachate concentrates. • Optimal operating conditions for electrochemical oxidation of landfill leachate concentrates is determined. • 87.5% COD removal and 74.06% NH{sub 3}−N removal were achieved after 6 h treatment. - Abstract: In the present study, the high quality boron-doped diamond (BDD) electrodes with excellent electrochemical properties were deposited on niobium (Nb) substrates by hot filament chemical vapor deposition (HFCVD) method. The electrochemical oxidation of landfill leachate concentrates from disc tube reverse osmosis (DTRO) process over a BDD anode was investigated. The effects of varying operating parameters, such as current density, initial pH, flow velocity and cathode material on degradation efficiency were also evaluated following changes in chemical oxygen demand (COD) and ammonium nitrogen (NH{sub 3}−N). The instantaneous current efficiency (ICE) was used to appraise different operating conditions. As a result, the best conditions obtained were as follows, current density 50 mA cm{sup −2}, pH 5.16, flow velocity 6 L h{sup −1}. Under these conditions, 87.5% COD and 74.06% NH{sub 3}−N removal were achieved after 6 h treatment, with specific energy consumption of 223.2 kWh m{sup −3}. In short, these results indicated that the electrochemical oxidation with BDD/Nb anode is an effective method for the treatment of landfill leachate concentrates.

  19. Tin Oxide Nanorod Array-Based Electrochemical Hydrogen Peroxide Biosensor

    Directory of Open Access Journals (Sweden)

    Liu Jinping

    2010-01-01

    Full Text Available Abstract SnO2 nanorod array grown directly on alloy substrate has been employed as the working electrode of H2O2 biosensor. Single-crystalline SnO2 nanorods provide not only low isoelectric point and enough void spaces for facile horseradish peroxidase (HRP immobilization but also numerous conductive channels for electron transport to and from current collector; thus, leading to direct electrochemistry of HRP. The nanorod array-based biosensor demonstrates high H2O2 sensing performance in terms of excellent sensitivity (379 μA mM−1 cm−2, low detection limit (0.2 μM and high selectivity with the apparent Michaelis–Menten constant estimated to be as small as 33.9 μM. Our work further demonstrates the advantages of ordered array architecture in electrochemical device application and sheds light on the construction of other high-performance enzymatic biosensors.

  20. Advanced Wastewater Photo-oxidation System, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Pioneer Astronautics proposes an advanced photocatalytic oxidation reactor for enhancing the reliability and performance of Water Recovery Post Processing systems...

  1. 3,5-Diamino-1,2,4-triazole@electrochemically reduced graphene oxide film modified electrode for the electrochemical determination of 4-nitrophenol

    International Nuclear Information System (INIS)

    Kumar, Deivasigamani Ranjith; Kesavan, Srinivasan; Baynosa, Marjorie Lara; Shim, Jae-Jin

    2017-01-01

    Highlights: •Triazole film was formed on electrochemically reduced graphene oxide. •pDAT@ERGO/GC was utilized for the electrochemical determination of 4-nitrophenol. •pDAT@ERGO/GC electrode offered wide concentration and nanomolar detection limit. •The fabricated electrode was employed in water sample analyses. -- Abstract: In this study, an eco-friendly benign method for the modification of electrochemically reduced graphene oxide (ERGO) on glassy carbon (GC) surface and electrochemical polymerized 3,5-diamino-1,2,4-triazole (DAT) film composite (pDAT@ERGO/GC) electrode was developed. The surface morphologies of the pDAT@ERGO/GC modified electrode were analyzed by field emission scanning electron microscopy (FESEM). FESEM images indicated that the ERGO supported pDAT has an almost homogeneous morphology structure with a size of 70 to 80 nm. It is due to the water oxidation reaction occurred while pDAT@ERGO/GC fabrication peak at +1.4 V leads to O 2 evolution and oxygen functional group functionalization on ERGO, which confirmed by X-ray photoelectron spectroscopy (XPS). In contrast, the bare GC modified with pDAT showed randomly arranged irregular bulky morphology structure compared to those of pDAT@ERGO/GC. Electrochemical reduction of graphene oxide was confirmed by Raman spectroscopy, XPS, and electrochemical impedance spectroscopy (EIS). The pDAT@ERGO/GC modified electrode was used for the electrochemical determination of 4-nitrophenol (4-NP). The 4-NP oxidation peak was observed at +0.25 V, and the differential pulse voltammetry demonstrated wide concentration range (5–1500 μM), high sensitivity (0.7113 μA μM −1 ), and low limit of detection (37 nM). Moreover, the pDAT@ERGO/GC electrode was applied to real water sample analysis by standard addition method, where in good recoveries (97.8% to 102.4%) were obtained.

  2. Designing Advanced Ceramic Waste Forms for Electrochemical Processing Salt Waste

    International Nuclear Information System (INIS)

    Ebert, W. L.; Snyder, C. T.; Frank, Steven; Riley, Brian

    2016-01-01

    This report describes the scientific basis underlying the approach being followed to design and develop ''advanced'' glass-bonded sodalite ceramic waste form (ACWF) materials that can (1) accommodate higher salt waste loadings than the waste form developed in the 1990s for EBR-II waste salt and (2) provide greater flexibility for immobilizing extreme waste salt compositions. This is accomplished by using a binder glass having a much higher Na_2O content than glass compositions used previously to provide enough Na+ to react with all of the Cl- in the waste salt and generate the maximum amount of sodalite. The phase compositions and degradation behaviors of prototype ACWF products that were made using five new binder glass formulations and with 11-14 mass% representative LiCl/KCl-based salt waste were evaluated and compared with results of similar tests run with CWF products made using the original binder glass with 8 mass% of the same salt to demonstrate the approach and select a composition for further studies. About twice the amount of sodalite was generated in all ACWF materials and the microstructures and degradation behaviors confirmed our understanding of the reactions occurring during waste form production and the efficacy of the approach. However, the porosities of the resulting ACWF materials were higher than is desired. These results indicate the capacity of these ACWF waste forms to accommodate LiCl/KCl-based salt wastes becomes limited by porosity due to the low glass-to-sodalite volume ratio. Three of the new binder glass compositions were acceptable and there is no benefit to further increasing the Na content as initially planned. Instead, further studies are needed to develop and evaluate alternative production methods to decrease the porosity, such as by increasing the amount of binder glass in the formulation or by processing waste forms in a hot isostatic press. Increasing the amount of binder glass to eliminate porosity will decrease the waste

  3. Surface properties of nanostructured NiO undergoing electrochemical oxidation in 3-methoxy-propionitrile

    Energy Technology Data Exchange (ETDEWEB)

    Bonomo, Matteo [Department of Chemistry, University of Rome “La Sapienza”, Piazzale Aldo Moro 5, 00185 Rome (Italy); Marrani, Andrea Giacomo, E-mail: andrea.marrani@uniroma1.it [Department of Chemistry, University of Rome “La Sapienza”, Piazzale Aldo Moro 5, 00185 Rome (Italy); Novelli, Vittoria [Department of Chemistry, University of Rome “La Sapienza”, Piazzale Aldo Moro 5, 00185 Rome (Italy); Awais, Muhammad [Department of Industrial Engineering, “King Abdulaziz” University, Rabigh (Saudi Arabia); Solar Energy Conversion Strategic Research Cluster, University College Dublin (UCD), Belfield, Dublin 4 (Ireland); Dowling, Denis P. [Solar Energy Conversion Strategic Research Cluster, University College Dublin (UCD), Belfield, Dublin 4 (Ireland); School of Mechanical and Materials Engineering, University College Dublin (UCD), Belfield, Dublin 4 (Ireland); Vos, Johannes G. [School of Chemical Sciences, Dublin City University (DCU), Glasnevin, Dublin 9 (Ireland); Dini, Danilo [Department of Chemistry, University of Rome “La Sapienza”, Piazzale Aldo Moro 5, 00185 Rome (Italy); Solar Energy Conversion Strategic Research Cluster, University College Dublin (UCD), Belfield, Dublin 4 (Ireland)

    2017-05-01

    Highlights: • NiO porous thin films were prepared via RDS technique. • NiO electrodes were characterized in a nitrile based electrochemical cell. • NiO electrodes were studied by means of XPS. • The XP spectra excluded the formation of phases other than NiO. • The presence of ClO{sub 4}{sup −} as charge balancing species was evidenced. - Abstract: Nanostructured nickel oxide (NiO) was deposited in the configuration of thin film (thickness, l = 2–6 μm) onto fluorine-doped tin oxide (FTO) substrates via plasma-assisted rapid discharge sintering (RDS). Electrochemical cycling of RDS NiO in 3-methoxy-propionitrile (3-MPN) revealed two characteristic peaks of NiO oxidation which were associated to the surface-confined redox processes Ni(II) → Ni(III) and Ni(III) → Ni(IV). Grazing angle X-ray photoelectron spectroscopy (XPS) was conducted ex-situ on NiO electrodes in both pristine and oxidized states. Oxidized NiO samples for XPS experiments were obtained in the potentiostatic mode through the polarization of NiO at its two characteristic potentials of oxidation. The XPS analysis allowed to ascertain the electronic structure of the nanoporous NiO framework, and verify the adsorption of perchlorate and chloride anions onto NiO surface due to the compensation of the charge stored in oxidized NiO. XPS also revealed that the spectrum within the region characteristic of Ni 2p ionization does not vary considerably with the state of charge of the nickel centres. This finding is in evident contrast to what has been observed for the same system when it undergoes electrochemical oxidation in aqueous electrolyte.

  4. Surface properties of nanostructured NiO undergoing electrochemical oxidation in 3-methoxy-propionitrile

    International Nuclear Information System (INIS)

    Bonomo, Matteo; Marrani, Andrea Giacomo; Novelli, Vittoria; Awais, Muhammad; Dowling, Denis P.; Vos, Johannes G.; Dini, Danilo

    2017-01-01

    Highlights: • NiO porous thin films were prepared via RDS technique. • NiO electrodes were characterized in a nitrile based electrochemical cell. • NiO electrodes were studied by means of XPS. • The XP spectra excluded the formation of phases other than NiO. • The presence of ClO 4 − as charge balancing species was evidenced. - Abstract: Nanostructured nickel oxide (NiO) was deposited in the configuration of thin film (thickness, l = 2–6 μm) onto fluorine-doped tin oxide (FTO) substrates via plasma-assisted rapid discharge sintering (RDS). Electrochemical cycling of RDS NiO in 3-methoxy-propionitrile (3-MPN) revealed two characteristic peaks of NiO oxidation which were associated to the surface-confined redox processes Ni(II) → Ni(III) and Ni(III) → Ni(IV). Grazing angle X-ray photoelectron spectroscopy (XPS) was conducted ex-situ on NiO electrodes in both pristine and oxidized states. Oxidized NiO samples for XPS experiments were obtained in the potentiostatic mode through the polarization of NiO at its two characteristic potentials of oxidation. The XPS analysis allowed to ascertain the electronic structure of the nanoporous NiO framework, and verify the adsorption of perchlorate and chloride anions onto NiO surface due to the compensation of the charge stored in oxidized NiO. XPS also revealed that the spectrum within the region characteristic of Ni 2p ionization does not vary considerably with the state of charge of the nickel centres. This finding is in evident contrast to what has been observed for the same system when it undergoes electrochemical oxidation in aqueous electrolyte.

  5. Microfluidic electrochemical sensor for on-line monitoring of aerosol oxidative activity.

    Science.gov (United States)

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

    2012-06-27

    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 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 (DTT) assay, where, after being oxidized by PM, the remaining reduced DTT is analyzed by the microfluidic sensor. The sensor consists of an array of working, reference, and auxiliary electrodes fabricated in a poly(dimethylsiloxane)-based microfluidic device. Cobalt(II) phthalocyanine-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 (R(2) from 0.86 to 0.97) with a time resolution of approximately 3 min.

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

    Science.gov (United States)

    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 π-π 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 π-π 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. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Peptide methionine sulfoxide reductase A (MsrA): direct electrochemical oxidation on carbon electrodes.

    Science.gov (United States)

    Enache, T A; Oliveira-Brett, A M

    2013-02-01

    The direct electrochemical behaviour of peptide methionine sulfoxide reductase A (MsrA) adsorbed on glassy carbon and boron doped diamond electrodes surface, was studied over a wide pH range by cyclic and differential pulse voltammetry. MsrA oxidation mechanism occurs in three consecutive, pH dependent steps, corresponding to the oxidation of tyrosine, tryptophan and histidine amino acid residues. At the glassy carbon electrode, the first step corresponds to the oxidation of tyrosine and tryptophan residues and occurs for the same potential. The advantage of boron doped diamond electrode was to enable the separation of tyrosine and tryptophan oxidation peaks. On the second step occurs the histidine oxidation, and on the third, at higher potentials, the second tryptophan oxidation. MsrA adsorbs on the hydrophobic carbon electrode surface preferentially through the three hydrophobic domains, C1, C2 and C3, which contain the tyrosine, tryptophan and histidine residues, and tryptophan exists only in these regions, and undergo electrochemical oxidation. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Destruction of commercial pesticides by cerium redox couple mediated electrochemical oxidation process in continuous feed mode

    International Nuclear Information System (INIS)

    Balaji, Subramanian; Chung, Sang Joon; Ryu, Jae-Yong; Moon, Il Shik

    2009-01-01

    Mediated electrochemical oxidation was carried out for the destruction of commercial pesticide formulations using cerium(IV) in nitric acid as the mediator electrolyte solution in a bench scale set up. The mediator oxidant was regenerated in situ using an electrochemical cell. The real application of this sustainable process for toxic organic pollutant destruction lies in its ability for long term continuous operation with continuous organic feeding and oxidant regeneration with feed water removal. In this report we present the results of fully integrated MEO system. The task of operating the continuous feed MEO system for a long time was made possible by continuously removing the feed water using an evaporator set up. The rate of Ce(IV) regeneration in the electrochemical cell and the consumption for the pesticide destruction was matched based on carbon content of the pesticides. It was found that under the optimized experimental conditions for Ce(III) oxidation, organic addition and water removal destruction efficiency of ca. 99% was obtained for all pesticides studied. It was observed that the Ce(IV) concentration was maintained nearly the same throughout the experiment. The stable operation for 6 h proved that the process can be used for real applications and for possible scale up for the destruction of larger volumes of toxic organic wastes.

  9. Electrochemical investigation of thermically treated graphene oxides as electrode materials for vanadium redox flow battery

    International Nuclear Information System (INIS)

    Di Blasi, O.; Briguglio, N.; Busacca, C.; Ferraro, M.; Antonucci, V.; Di Blasi, A.

    2015-01-01

    Highlights: • Graphene oxide is synthesized at high temperatures in a reducing environment. • Treated graphene oxide-based electrodes are prepared by the wet impregnation method. • Electrochemical performance is evaluated as a function of the physico-chemical properties. - Abstract: Thermically treated graphene oxides (TT-GOs) are synthesized at different temperatures, 100 °C, 150 °C, 200 °C and 300 °C in a reducing environment (20% H 2 /He) and investigated as electrode materials for vanadium redox flow battery (VRFB) applications. The treated graphene oxide-based electrodes are prepared by the wet impregnation method using carbon felt (CF) as support. The main aim is to achieve a suitable distribution of the dispersed graphene oxides on the CF surface in order to investigate the electrocatalytic activity for the VO 2+ /VO 2 + and V 2+ /V 3+ redox reactions in the perspective of a feasible large area electrodes scale-up for battery configuration of practical interest. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) are carried out in a three electrode half-cell to characterize the electrochemical properties of the TT-GO-based electrodes. Physico-chemical characterizations are carried out to corroborate the electrochemical results. The TT-GO sample treated at 100 °C (TT-GO-100) shows the highest electrocatalytic activity in terms of peak to peak separation (ΔE = 0.03 V) and current density intensity (∼0.24 A cm −2 at 30 mV/s) both toward the VO 2+ /VO 2 + and V 2+ /V 3+ redox reactions. This result is correlated to the presence of hydroxyl (−OH) and carboxyl (−COOH) species that act as active sites. A valid candidate is individuated as effective anode and cathode electrode in the perspective of electrodes scale-up for battery configuration of practical interest

  10. Electrochemical characterisation of solid oxide cell electrodes for hydrogen production

    DEFF Research Database (Denmark)

    Bernuy-Lopez, Carlos; Knibbe, Ruth; He, Zeming

    2011-01-01

    Oxygen electrodes and steam electrodes are designed and tested to develop improved solid oxide electrolysis cells for H2 production with the cell support on the oxygen electrode. The electrode performance is evaluated by impedance spectroscopy testing of symmetric cells at open circuit voltage (OCV...

  11. High performance fuel electrode for a solid oxide electrochemical cell

    DEFF Research Database (Denmark)

    2013-01-01

    perovskite oxides selected from the group consisting of niobium-doped strontium titanate, vanadium-doped strontium titanate, tantalum-doped strontium titanate and mixtures thereof, thereby obtaining a porous anode backbone, (b) sintering the coated electrolyte at a high temperature, such as 1200 DEG C...

  12. Enhanced electrochemical water oxidation: the impact of nanoclusters and nanocavities

    NARCIS (Netherlands)

    Zhang, X.; Cao, C.; Bieberle, A.

    2017-01-01

    The structures of transition metal surfaces and metal oxides are commonly believed to have a significant effect on the catalytic reactions. Density functional theory calculations are therefore used in this study to investigate the oxygen evolution reaction (OER) over nanostructured, i.e. nanocluster

  13. Recent Development of Advanced Electrode Materials by Atomic Layer Deposition for Electrochemical Energy Storage.

    Science.gov (United States)

    Guan, Cao; Wang, John

    2016-10-01

    Electrode materials play a decisive role in almost all electrochemical energy storage devices, determining their overall performance. Proper selection, design and fabrication of electrode materials have thus been regarded as one of the most critical steps in achieving high electrochemical energy storage performance. As an advanced nanotechnology for thin films and surfaces with conformal interfacial features and well controllable deposition thickness, atomic layer deposition (ALD) has been successfully developed for deposition and surface modification of electrode materials, where there are considerable issues of interfacial and surface chemistry at atomic and nanometer scale. In addition, ALD has shown great potential in construction of novel nanostructured active materials that otherwise can be hardly obtained by other processing techniques, such as those solution-based processing and chemical vapor deposition (CVD) techniques. This review focuses on the recent development of ALD for the design and delivery of advanced electrode materials in electrochemical energy storage devices, where typical examples will be highlighted and analyzed, and the merits and challenges of ALD for applications in energy storage will also be discussed.

  14. Advances and Perspectives in Chemical Imaging in Cellular Environments Using Electrochemical Methods

    Directory of Open Access Journals (Sweden)

    Robert A. Lazenby

    2018-05-01

    Full Text Available This review discusses a broad range of recent advances (2013–2017 in chemical imaging using electrochemical methods, with a particular focus on techniques that have been applied to study cellular processes, or techniques that show promise for use in this field in the future. Non-scanning techniques such as microelectrode arrays (MEAs offer high time-resolution (<10 ms imaging; however, at reduced spatial resolution. In contrast, scanning electrochemical probe microscopies (SEPMs offer higher spatial resolution (as low as a few nm per pixel imaging, with images collected typically over many minutes. Recent significant research efforts to improve the spatial resolution of SEPMs using nanoscale probes and to improve the temporal resolution using fast scanning have resulted in movie (multiple frame imaging with frame rates as low as a few seconds per image. Many SEPM techniques lack chemical specificity or have poor selectivity (defined by the choice of applied potential for redox-active species. This can be improved using multifunctional probes, ion-selective electrodes and tip-integrated biosensors, although additional effort may be required to preserve sensor performance after miniaturization of these probes. We discuss advances to the field of electrochemical imaging, and technological developments which are anticipated to extend the range of processes that can be studied. This includes imaging cellular processes with increased sensor selectivity and at much improved spatiotemporal resolution than has been previously customary.

  15. Zn2+-Doped Polyaniline/Graphene Oxide as Electrode Material for Electrochemical Supercapacitors

    Science.gov (United States)

    Xu, Hui; Tang, Jing; Chen, Yong; Liu, Jian; Pu, Jinjuan; Li, Qi

    2017-10-01

    Electrodes based on Zn2+-doped polyaniline/graphene oxide (Zn2+/PANI/GO) were synthesized on stainless steel mesh substrates in H2SO4 solution via electrochemical codeposition. Different concentrations of graphene oxide (GO) were incorporated into the films to improve the electrochemical performance of the electrodes. Electrochemical properties of the films were tested by cyclic voltammetry, galvanostatic charge-discharge tests, and electrochemical impedance spectroscopy, in a three-electrode system. The maximum specific capacitance of the Zn2+/PANI/GO film with a GO concentration of 15 mg L-1 was found to be 1266 F g-1 at a scan rate of 3 mV s-1. This value was higher than that of a Zn2+ doped polyaniline (Zn2+/PANI) film (814 F g-1). The Zn2+/PANI/GO film also showed good cycling stability, retaining over 86% of its initial capacitance after 1000 cycles. These results indicate that the Zn2+/PANI/GO composites can be applied as high performance supercapacitor electrodes.

  16. Electrodeposited nickel oxide and graphene modified carbon ionic liquid electrode for electrochemical myglobin biosensor

    International Nuclear Information System (INIS)

    Sun, Wei; Gong, Shixing; Deng, Ying; Li, Tongtong; Cheng, Yong; Wang, Wencheng; Wang, Lei

    2014-01-01

    By using ionic liquid 1-hexylpyridinium hexafluorophosphate based carbon ionic liquid electrode (CILE) as the substrate electrode, graphene (GR) and nickel oxide (NiO) were in situ electrodeposited step by step to get a NiO/GR nanocomposite modified CILE. Myoglobin (Mb) was further immobilized on the surface of NiO/GR/CILE with a Nafion film to get the electrochemical sensor denoted as Nafion/Mb/NiO/GR/CILE. Cyclic voltammetric experiments indicated that a pair of well-defined quasi-reversible redox peaks appeared in pH 3.0 phosphate buffer solution with the formal peak potential (E 0′ ) located at − 0.188 V (vs. SCE), which was the typical characteristics of Mb Fe(III)/Fe(II) redox couples. So the direct electron transfer of Mb was realized and promoted due to the presence of the NiO/GR nanocomposite on the electrode. Based on the cyclic voltammetric data, the electrochemical parameters of Mb on the modified electrode were calculated. The Mb modified electrode showed an excellent electrocatalytic activity towards the reduction of different substrates including trichloroacetic acid and H 2 O 2 . Therefore a third-generation electrochemical Mb biosensor based on NiO/GR/CILE was constructed with good stability and reproducibility. - Highlights: • Graphene and nickel oxide nanocomposites were prepared by electrodeposition. • Electrochemical myoglobin sensor was prepared on a nanocomposite modified electrode. • Direct electrochemistry and electrocatalysis of myglobin were realized

  17. Facile synthesis of cuprous oxide nanowires decorated graphene oxide nanosheets nanocomposites and its application in label-free electrochemical immunosensor.

    Science.gov (United States)

    Wang, Huan; Zhang, Yong; Wang, Yulan; Ma, Hongmin; Du, Bin; Wei, Qin

    2017-01-15

    In this work, the assembly between one-dimensional (1D) nanomaterials and two-dimensional (2D) nanomaterials was achieved by a simple method. Cuprous oxide nanowires decorated graphene oxide nanosheets (Cu 2 O@GO) nanocomposites were synthesized for the first time by a simple electrostatic self-assembly process. The nanostructure was well confirmed by scanning electron microscope (SEM) and transmission electron microscope (TEM) images. Taking advantages of good electrocatalytic activity and high specific surface area of Cu 2 O@GO nanocomposites, a label-free electrochemical immunosensor was developed by employing Cu 2 O@GO as signal amplification platform for the quantitative detection of alpha fetoprotein (AFP). In addition, toluidine blue (TB) was used as the electron transfer mediator to provide the electrochemical signal, which was adsorbed on graphene oxide nanosheets (GO NSs) by electrostatic attraction. The detection mechanism was based on the monitoring of the electrochemical current response change of TB by the square wave voltammetry (SWV) when immunoreaction occurred on the surface of electrode. Under optimal conditions, the proposed immunosensor displayed a high sensitivity and a low detection limit. This designed method may provide an effective method in the clinical diagnosis of AFP and other tumor markers. Copyright © 2016 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

    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.

  19. Electrodeposition of Manganese-Nickel Oxide Films on a Graphite Sheet for Electrochemical Capacitor Applications

    Directory of Open Access Journals (Sweden)

    Hae-Min Lee

    2014-01-01

    Full Text Available Manganese-nickel (Mn-Ni oxide films were electrodeposited on a graphite sheet in a bath consisting of manganese acetate and nickel chloride, and the structural, morphological, and electrochemical properties of these films were investigated. The electrodeposited Mn-Ni oxide films had porous structures covered with nanofibers. The X-ray diffractometer pattern revealed the presence of separate manganese oxide (g-MnO2 and nickel oxide (NiO in the films. The electrodeposited Mn-Ni oxide electrode exhibited a specific capacitance of 424 F/g in Na2SO4 electrolyte. This electrode maintained 86% of its initial specific capacitance over 2000 cycles of the charge-discharge operation, showing good cycling stability.

  20. Facile solvothermal synthesis of a graphene nanosheet-bismuth oxide composite and its electrochemical characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Wang Huanwen [Key Laboratory of Eco-Environment-Related Polymer Materials of Ministry of Education, Key Laboratory of Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China); Hu Zhongai, E-mail: zhongai@nwnu.edu.c [Key Laboratory of Eco-Environment-Related Polymer Materials of Ministry of Education, Key Laboratory of Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China); Chang Yanqin; Chen Yanli; Lei Ziqiang; Zhang Ziyu; Yang Yuying [Key Laboratory of Eco-Environment-Related Polymer Materials of Ministry of Education, Key Laboratory of Polymer Materials of Gansu Province, College of Chemistry and Chemical Engineering, Northwest Normal University, Lanzhou 730070 (China)

    2010-12-01

    This work demonstrates a novel and facile route for preparing graphene-based composites comprising of metal oxide nanoparticles and graphene. A graphene nanosheet-bismuth oxide composite as electrode materials of supercapacitors was firstly synthesized by thermally treating the graphene-bismuth composite, which was obtained through simultaneous solvothermal reduction of the colloidal dispersions of negatively charged graphene oxide sheets in N,N-dimethyl formamide (DMF) solution of bismuth cations at 180 {sup o}C. The morphology, composition, and microstructure of the composites together with pure graphite oxide, and graphene were characterized using powder X-ray diffraction (XRD), FT-IR, field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), thermogravimetry and differential thermogravimetry (TG-DTG). The electrochemical behaviors were measured by cyclic voltammogram (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS). The specific capacitance of 255 F g{sup -1} (based on composite) is obtained at a specific current of 1 A g{sup -1} as compared with 71 F g{sup -1} for pure graphene. The loaded-bismuth oxide achieves a specific capacitance as high as 757 F g{sup -1} even at 10 A g{sup -1}. In addition, the graphene nanosheet-bismuth oxide composite electrode exhibits the excellent rate capability and well reversibility.

  1. Facile solvothermal synthesis of a graphene nanosheet-bismuth oxide composite and its electrochemical characteristics

    International Nuclear Information System (INIS)

    Wang Huanwen; Hu Zhongai; Chang Yanqin; Chen Yanli; Lei Ziqiang; Zhang Ziyu; Yang Yuying

    2010-01-01

    This work demonstrates a novel and facile route for preparing graphene-based composites comprising of metal oxide nanoparticles and graphene. A graphene nanosheet-bismuth oxide composite as electrode materials of supercapacitors was firstly synthesized by thermally treating the graphene-bismuth composite, which was obtained through simultaneous solvothermal reduction of the colloidal dispersions of negatively charged graphene oxide sheets in N,N-dimethyl formamide (DMF) solution of bismuth cations at 180 o C. The morphology, composition, and microstructure of the composites together with pure graphite oxide, and graphene were characterized using powder X-ray diffraction (XRD), FT-IR, field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), thermogravimetry and differential thermogravimetry (TG-DTG). The electrochemical behaviors were measured by cyclic voltammogram (CV), galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS). The specific capacitance of 255 F g -1 (based on composite) is obtained at a specific current of 1 A g -1 as compared with 71 F g -1 for pure graphene. The loaded-bismuth oxide achieves a specific capacitance as high as 757 F g -1 even at 10 A g -1 . In addition, the graphene nanosheet-bismuth oxide composite electrode exhibits the excellent rate capability and well reversibility.

  2. Electrochemical treatment of wastewater: A case study of reduction of DNT and oxidation of chlorinated phenols

    Energy Technology Data Exchange (ETDEWEB)

    Rodgers, J.D.; Bunce, N.J.; Jedral, W.

    1999-07-01

    Electrochemical treatment is under consideration as a treatment option for several recalcitrant compounds. In this work the authors investigate the oxidation of chlorophenols and the reduction of nitroaromatics. In the case of chlorinated phenols, they explore the problem of anode fouling which has hampered electrolytic treatment of phenolic compounds by examining phenols differing in the extent of chlorination, according to the mechanism of oxidation at different electrode types. Linear sweep voltammograms at a Pt anode were interpreted in terms of deposition of oligomers on the anode surface. Passivation increased in parallel with the uncompensated resistance of the solution and occurred only at potentials at which water is oxidized, suggesting that the formation of the oligomer film involves attack of hydroxyl radicals on electrochemically oxidized substrate. Relative reactivities of congeners were anode-dependent, due to different mechanisms of oxidation: direct electron transfer oxidation at PbO{sub 2} and hydroxyl radical attack at SnO{sub 2} and IrO{sub 2}. Voltammetry of 2,6-dinitrotoluene (DNT) was consistent with literature values. DNT was reduced at several cathodes with the most promising result at Ni-plated Ni wire. At current densities {lt} 0.1 mA cm{sup {minus}2}, current efficiencies {gt} 50% could be achieved with 4-chlorophenol at all three anodes and for 2,6-DNT at Ni-plated Ni wire.

  3. One step paired electrochemical synthesis of iron and iron oxide nanoparticles

    Directory of Open Access Journals (Sweden)

    Ordoukhanian Juliet

    2016-09-01

    Full Text Available In this study, a new one step paired electrochemical method is developed for simultaneous synthesis of iron and iron oxide nanoparticles. iron and iron oxide are prepared as cathodic and anodic products from iron (ii sulfate aqueous solution in a membrane divided electrolytic cell by the pulsed current electrosynthesis. Because of organic solvent-free and electrochemical nature of the synthesis, the process could be considered as green and environmentally friendly. The reduction of energy consumption and low cost are the other significant advantages of this new method that would have a great application potential in the chemical industry. The nanostructure of prepared samples was characterized by Fourier transform infrared spectroscopy (FT-IR, X-ray diffraction (XRD, scanning electron microscopy (SEM and transmission electron microscopy (TEM. The magnetic properties were studied by vibrating sample magnetometer (VsM.

  4. Electrochemical energy storage devices using electrodes incorporating carbon nanocoils and metal oxides nanoparticles

    KAUST Repository

    Baby, Rakhi Raghavan

    2011-07-28

    Carbon nanocoil (CNC) based electrodes are shown to be promising candidates for electrochemical energy storage applications, provided the CNCs are properly functionalized. In the present study, nanocrystalline metal oxide (RuO 2, MnO2, and SnO2) dispersed CNCs were investigated as electrodes for supercapacitor applications using different electrochemical methods. In the two electrode configuration, the samples exhibited high specific capacitance with values reaching up to 311, 212, and 134 F/g for RuO2/CNCs, MnO2/CNCs, and SnO2/CNCs, respectively. The values obtained for specific capacitance and maximum storage energy per unit mass of the composites were found to be superior to those reported for metal oxide dispersed multiwalled carbon nanotubes in two electrode configuration. In addition, the fabricated supercapacitors retained excellent cycle life with ∼88% of the initial specific capacitance retained after 2000 cycles. © 2011 American Chemical Society.

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

    Directory of Open Access Journals (Sweden)

    Xiwen He

    2013-04-01

    Full Text Available 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.

  6. Oxidative stabilization of polyacrylonitrile nanofibers and carbon nanofibers containing graphene oxide (GO: a spectroscopic and electrochemical study

    Directory of Open Access Journals (Sweden)

    İlknur Gergin

    2017-08-01

    Full Text Available In this study, a precursor for carbon nanofibers (CNF was fabricated via electrospinning and carbonized through a thermal process. Before carbonization, oxidative stabilization should be applied, and the oxidation mechanism also plays an important role during carbonization. Thus, the understanding of the oxidation mechanism is an essential part of the production of CNF. The oxidation process of polyacrylonitrile was studied and nanofiber webs containing graphene oxide (GO are obtained to improve the electrochemical properties of CNF. Structural and morphological characterizations of the webs are carried out by using attenuated total reflectance Fourier transform infrared spectroscopy and Raman spectroscopy, scanning electron microscopy, atomic force microscopy and transmission electron microscopy. Mechanical tests are performed with a dynamic mechanical analyzer, and thermal studies are conducted by using thermogravimetric analysis. Electrochemical impedance spectroscopy, and cyclic voltammetry are used to investigate capacitive behavior of the products. The proposed equivalent circuit model was consistent with charge-transfer processes taking place at interior pores filled with electrolyte.

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

    Science.gov (United States)

    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. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Electrochemically oxidized electronic and ionic conducting nanostructured block copolymers for lithium battery electrodes.

    Science.gov (United States)

    Patel, Shrayesh N; Javier, Anna E; Balsara, Nitash P

    2013-07-23

    Block copolymers that can simultaneously conduct electronic and ionic charges on the nanometer length scale can serve as innovative conductive binder material for solid-state battery electrodes. The purpose of this work is to study the electronic charge transport of poly(3-hexylthiophene)-b-poly(ethylene oxide) (P3HT-PEO) copolymers electrochemically oxidized with lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) salt in the context of a lithium battery charge/discharge cycle. We use a solid-state three-terminal electrochemical cell that enables simultaneous conductivity measurements and control over electrochemical doping of P3HT. At low oxidation levels (ratio of moles of electrons removed to moles of 3-hexylthiophene moieties in the electrode), the electronic conductivity (σe,ox) increases from 10(-7) S/cm to 10(-4) S/cm. At high oxidation levels, σe,ox approaches 10(-2) S/cm. When P3HT-PEO is used as a conductive binder in a positive electrode with LiFePO4 active material, P3HT is electrochemically active within the voltage window of a charge/discharge cycle. The electronic conductivity of the P3HT-PEO binder is in the 10(-4) to 10(-2) S/cm range over most of the potential window of the charge/discharge cycle. This allows for efficient electronic conduction, and observed charge/discharge capacities approach the theoretical limit of LiFePO4. However, at the end of the discharge cycle, the electronic conductivity decreases sharply to 10(-7) S/cm, which means the "conductive" binder is now electronically insulating. The ability of our conductive binder to switch between electronically conducting and insulating states in the positive electrode provides an unprecedented route for automatic overdischarge protection in rechargeable batteries.

  9. Solid State Electrochemical Sensors for Nitrogen Oxide (NOx) Detection in Lean Exhaust Gases

    OpenAIRE

    Rheaume, Jonathan Michael

    2010-01-01

    Solid state electrochemical sensors that measure nitrogen oxides (NOx) in lean exhaust have been investigated in order to help meet future on-board diagnostic (OBD) regulations for diesel vehicles. This impedancemetric detection technology consists of a planar, single cell sensor design with various sensing electrode materials and yttria-stabilized zirconia (YSZ) as the electrolyte. No reference to ambient air is required. An impedance analysis method yields a signal that is proportional to t...

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

    International Nuclear Information System (INIS)

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

    1999-01-01

    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

  11. Performance of electrochemical oxidation and photocatalysis in terms of kinetics and energy consumption. New insights into the p-cresol degradation.

    Science.gov (United States)

    Escudero, Carlos J; Iglesias, Olalla; Dominguez, Sara; Rivero, Maria J; Ortiz, Inmaculada

    2017-06-15

    This work reports the comparative performance of two Advanced Oxidation Processes (AOPs), electrochemical oxidation and photocatalysis, as individual technological alternatives for the treatment of effluents containing p-cresol. First, the influence of operating parameters in the oxidation and mineralization yield was carried out together with kinetic analysis. Boron Doped Diamond (BDD), RuO 2 and Pt as anodic materials, Na 2 SO 4 and NaCl as supporting electrolytes and different current densities were evaluated in electrochemical oxidation whereas the effect of TiO 2 concentration and radiation was studied in the photocatalytic degradation. Then, the parameter Electrical Energy per Order (E EO ) was calculated to compare the energy consumption in both AOPs, concluding that under the studied conditions the electrochemical treatment with BDD, Na 2 SO 4 and 125 A m -2 showed the best energy efficiency, with an E EO of 5.83 kW h m -3 order -1 for p-cresol and 58.05 kW h m -3 order -1 for DOC removal, respectively. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Electrochemical degradation of clofibric acid in water by anodic oxidation

    International Nuclear Information System (INIS)

    Sires, Ignasi; Cabot, Pere Lluis; Centellas, Francesc; Garrido, Jose Antonio; Rodriguez, Rosa Maria; Arias, Conchita; Brillas, Enric

    2006-01-01

    Aqueous solutions containing the metabolite clofibric acid (2-(4-chlorophenoxy)-2-methylpropionic acid) up to close to saturation in the pH range 2.0-12.0 have been degraded by anodic oxidation with Pt and boron-doped diamond (BDD) as anodes. The use of BDD leads to total mineralization in all media due to the efficient production of oxidant hydroxyl radical (·OH). This procedure is then viable for the treatment of wastewaters containing this compound. The effect of pH, apparent current density, temperature and metabolite concentration on the degradation rate, consumed specific charge and mineralization current efficiency has been investigated. Comparative treatment with Pt yields poor decontamination with complete release of stable chloride ion. When BDD is used, this ion is oxidized to Cl 2 . Clofibric acid is more rapidly destroyed on Pt than on BDD, indicating that it is more strongly adsorbed on the Pt surface enhancing its reaction with ·OH. Its decay kinetics always follows a pseudo-first-order reaction and the rate constant for each anode increases with increasing apparent current density, being practically independent of pH and metabolite concentration. Aromatic products such as 4-chlorophenol, 4-chlorocatechol, 4-chlororesorcinol, hydroquinone, p-benzoquinone and 1,2,4-benzenetriol are detected by gas chromatography-mass spectrometry (GC-MS) and reversed-phase chromatography. Tartronic, maleic, fumaric, formic, 2-hydroxyisobutyric, pyruvic and oxalic acids are identified as generated carboxylic acids by ion-exclusion chromatography. These acids remain stable in solution using Pt, but they are completely converted into CO 2 with BDD. A reaction pathway for clofibric acid degradation involving all these intermediates is proposed

  13. Electrochemical degradation of clofibric acid in water by anodic oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Sires, Ignasi [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Cabot, Pere Lluis [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Centellas, Francesc [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Garrido, Jose Antonio [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Rodriguez, Rosa Maria [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Arias, Conchita [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain); Brillas, Enric [Laboratori de Ciencia i Tecnologia Electroquimica de Materials, Departament de Quimica Fisica, Facultat de Quimica, Universitat de Barcelona, Marti i Franques 1-11, 08028 Barcelona (Spain)]. E-mail: brillas@ub.edu

    2006-10-05

    Aqueous solutions containing the metabolite clofibric acid (2-(4-chlorophenoxy)-2-methylpropionic acid) up to close to saturation in the pH range 2.0-12.0 have been degraded by anodic oxidation with Pt and boron-doped diamond (BDD) as anodes. The use of BDD leads to total mineralization in all media due to the efficient production of oxidant hydroxyl radical ({center_dot}OH). This procedure is then viable for the treatment of wastewaters containing this compound. The effect of pH, apparent current density, temperature and metabolite concentration on the degradation rate, consumed specific charge and mineralization current efficiency has been investigated. Comparative treatment with Pt yields poor decontamination with complete release of stable chloride ion. When BDD is used, this ion is oxidized to Cl{sub 2}. Clofibric acid is more rapidly destroyed on Pt than on BDD, indicating that it is more strongly adsorbed on the Pt surface enhancing its reaction with {center_dot}OH. Its decay kinetics always follows a pseudo-first-order reaction and the rate constant for each anode increases with increasing apparent current density, being practically independent of pH and metabolite concentration. Aromatic products such as 4-chlorophenol, 4-chlorocatechol, 4-chlororesorcinol, hydroquinone, p-benzoquinone and 1,2,4-benzenetriol are detected by gas chromatography-mass spectrometry (GC-MS) and reversed-phase chromatography. Tartronic, maleic, fumaric, formic, 2-hydroxyisobutyric, pyruvic and oxalic acids are identified as generated carboxylic acids by ion-exclusion chromatography. These acids remain stable in solution using Pt, but they are completely converted into CO{sub 2} with BDD. A reaction pathway for clofibric acid degradation involving all these intermediates is proposed.

  14. Boron doped ZnO embedded into reduced graphene oxide for electrochemical supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Alver, Ü., E-mail: ualver@ktu.edu.tr [Karadeniz Technical University, Dept. of Metallurgical and Materials Engineering, 61080 Trabzon (Turkey); Tanrıverdi, A. [Kahramanmaras Sutcu Imam University, Department of Physics, 46100 Kahramanmaraş (Turkey)

    2016-08-15

    Highlights: • Boron doped ZnO particles are fabricated and embedded into reduced graphene oxide (RGO) by hydrothermal method. • RGO/ZnO:B composites are used as electrodes for supercapacitors. • Presence of boron in RGO/ZnO composites caused increasing the stability and specific capacitance of electrodes. - Abstract: In this work, reduced graphene oxide/boron doped zinc oxide (RGO/ZnO:B) composites were fabricated by a hydrothermal process and their electrochemical properties were investigated as a function of dopant concentration. First, boron doped ZnO (ZnO:B) particles was fabricated with different boron concentrations (5, 10, 15 and 20 wt%) and then ZnO:B particles were embedded into RGO sheets. The physical properties of sensitized composites were characterized by XRD and SEM. Characterization indicated that the ZnO:B particles with plate-like structure in the composite were dispersed on graphene sheets. The electrochemical properties of the RGO/ZnO:B composite were investigated through cyclic voltammetry, galvanostatic charge/discharge measurements in a 6 M KOH electrolyte. Electrochemical measurements show that the specific capacitance values of RGO/ZnO:B electrodes increase with increasing boron concentration. RGO/ZnO:B composite electrodes (20 wt% B) display the specific capacitance as high as 230.50 F/g at 5 mV/s, which is almost five times higher than that of RGO/ZnO (52.71 F/g).

  15. Boron doped ZnO embedded into reduced graphene oxide for electrochemical supercapacitors

    International Nuclear Information System (INIS)

    Alver, Ü.; Tanrıverdi, A.

    2016-01-01

    Highlights: • Boron doped ZnO particles are fabricated and embedded into reduced graphene oxide (RGO) by hydrothermal method. • RGO/ZnO:B composites are used as electrodes for supercapacitors. • Presence of boron in RGO/ZnO composites caused increasing the stability and specific capacitance of electrodes. - Abstract: In this work, reduced graphene oxide/boron doped zinc oxide (RGO/ZnO:B) composites were fabricated by a hydrothermal process and their electrochemical properties were investigated as a function of dopant concentration. First, boron doped ZnO (ZnO:B) particles was fabricated with different boron concentrations (5, 10, 15 and 20 wt%) and then ZnO:B particles were embedded into RGO sheets. The physical properties of sensitized composites were characterized by XRD and SEM. Characterization indicated that the ZnO:B particles with plate-like structure in the composite were dispersed on graphene sheets. The electrochemical properties of the RGO/ZnO:B composite were investigated through cyclic voltammetry, galvanostatic charge/discharge measurements in a 6 M KOH electrolyte. Electrochemical measurements show that the specific capacitance values of RGO/ZnO:B electrodes increase with increasing boron concentration. RGO/ZnO:B composite electrodes (20 wt% B) display the specific capacitance as high as 230.50 F/g at 5 mV/s, which is almost five times higher than that of RGO/ZnO (52.71 F/g).

  16. Electrochemical study on the cationic promotion of the catalytic SO2 oxidation in pyrosulfate melts

    DEFF Research Database (Denmark)

    Petrushina, Irina; Bjerrum, Niels; Cappeln, Frederik Vilhelm

    1998-01-01

    The electrochemical behavior of the molten V2O5-M2S2O7 (M = K, Cs, or Na) system was studied using a gold working electrode at 440 degrees C in argon and air atmosphere. The aim of the present investigation was to find a possible correlation between the promoting effect of Cs+ and Na+ ions...... on the catalytic oxidation of SO2 in the V2O5-M2S2O7 system and the effect of these alkali cations on the electrochemical behavior of V2O5 in the alkali pyrosulfate melts It has been shown that Na+ ions had a promoting effect on the V(V) reversible arrow V(IV) electrochemical reaction. Sodium ions accelerate both...... in the catalytic SO, oxidation most likely is the oxidation of V(IV) to V(V) and the Na+ and Cs+ promoting effect is based on the acceleration of this stage. It has also been proposed that voltammetric measurements can be used for fast optimization of the composition of the vanadium catalyst (which...

  17. Indirect Electrochemical Oxidation with Multi Carbon Electrodes for Restaurant Wastewater Treatment

    Directory of Open Access Journals (Sweden)

    I Dewa Ketut Sastrawidana

    2018-01-01

    Full Text Available The removal of organic matter from the restaurant wastewater was investigated using the electrochemical oxida-tion method with multi carbon electrodes in a parallel construction. The degradation process was monitored by the measurement of COD concentration as a function of electrolysis time. The effectof operating parameter conditions on COD removal were investigated including initial pH, distance between electrodes, and the applied voltage difference.The results showed that the treatment of restaurant wastewater containing 2 g/L chloride ion using the electrochemical oxidation technique at the operation conditions characterized by: pH 5, distance between electrode of 10 cm and applied voltage of 12 V, enabled to obtained COD removal of 92.84% within 90 min electrolysis time. It is can be concluded that the indirect electrochemical oxidation method with multi carbon electrodes can be used effectivelyas an alternative technology for reducing COD and may be potentially applied for removal organic pollutants from wastewater at the industrial scale.

  18. Advanced oxidation technologies for chemical demilitarization

    Energy Technology Data Exchange (ETDEWEB)

    Rosocha, L.A.; Korzekwa, R.A.; Monagle, M.; Coogan, J.J.; Tennant, R.A.; Brown, L.F.; Currier, R.P.

    1996-12-31

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory. The main project objective was to establish a technical basis for future program development in the area of chemical warfare agent destruction using a Los Alamos-developed advanced oxidation process: a two-stage device consisting of thermal packed-bed reactor (PBR) and a nonthermal plasma (NTP) reactor. Various compounds were evaluated as potential surrogates for chemical warfare (CW) agents. Representative effluent mass balances were projected for future comparisons with incinerators. The design and construction of lab-scale PBR/NTP reactors (consisting of a liquid injection and metering system, electric furnace, condensers, chemical traps, plasma reactors, power supplies, and chemical diagnostics) has been completed. This equipment, the experience gained from chemical-processing experiments, process modeling, and an initial demonstration of the feasibility of closed-loop operation, have provided a technical basis for further demonstrations and program development efforts.

  19. Direct electrochemistry and electrocatalysis of lobetyolin via magnetic functionalized reduced graphene oxide film fabricated electrochemical sensor

    International Nuclear Information System (INIS)

    Sun, Bolu; Gou, Xiaodan; Bai, Ruibin; Abdelmoaty, Ahmed Attia Ahmed; Ma, Yuling; Zheng, Xiaoping; Hu, Fangdi

    2017-01-01

    A novel lobetyolin electrochemical sensor based on a magnetic functionalized reduced graphene oxide/Nafion nanohybrid film has been introduced in this work. The magnetic functionalized reduced graphene oxide was characterized by fourier transform infrared spectroscopy, atomic force microscope, X-ray diffraction, transmission electron microscopy and thermogravimetric analysis. The scanning electron microscopy characterized the morphology and microstructure of the prepared sensors, and the electrochemical effective surface areas of the prepared sensors were also calculated by chronocoulometry method. The electrochemical behavior of lobetyolin on the magnetic functionalized reduced graphene oxide/Nafion nanohybrid modified glassy carbon electrode was investigated by cyclic voltammetry and differential pulse voltammetry in a phosphate buffer solution of pH 6.0. The electron-transfer coefficient (α), electron transfer number (n), and electrode reaction rate constant (Κs) were calculated as 0.78, 0.73, and 4.63 s −1 , respectively. Under the optimized conditions, the sensor based on magnetic functionalized reduced graphene oxide/Nafion showed a linear voltammetric response to the lobetyolin concentration at 1.0 × 10 −7 to 1.0 × 10 −4 mol/L with detection limit (S/N = 3)of 4.3 × 10 −8 mol/L. The proposed sensor also displayed acceptable reproducibility, long-term stability, and high selectivity, and performs well for analysis of lobetyolin in real samples. The voltammetric sensor was successfully applied to detect lobetyolin in Codonopsis pilosula with recovery values in the range of 96.12% –102.66%. - Graphical abstract: Schematic diagram of the synthesis of MrGO hybrid and the fabrication process of the MrGO/Nafion/GCE for determination of lobetyolin. Display Omitted - Highlights: • The MrGO/Nafion@GCE electrochemical sensor was successfully fabricated. • The prepared MrGO was characterized by AFM, XRD, FTIR, VSM, TEM and SEM. • The proposed

  20. Direct electrochemistry and electrocatalysis of lobetyolin via magnetic functionalized reduced graphene oxide film fabricated electrochemical sensor

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Bolu [School of Pharmacy, Lanzhou University, Lanzhou 730000 (China); Gou, Xiaodan [School of Chemistry and Chemical Engineering, Nanjing University, 210046 (China); Bai, Ruibin; Abdelmoaty, Ahmed Attia Ahmed; Ma, Yuling; Zheng, Xiaoping [School of Pharmacy, Lanzhou University, Lanzhou 730000 (China); Hu, Fangdi, E-mail: hufd@lzu.edu.cn [School of Pharmacy, Lanzhou University, Lanzhou 730000 (China)

    2017-05-01

    A novel lobetyolin electrochemical sensor based on a magnetic functionalized reduced graphene oxide/Nafion nanohybrid film has been introduced in this work. The magnetic functionalized reduced graphene oxide was characterized by fourier transform infrared spectroscopy, atomic force microscope, X-ray diffraction, transmission electron microscopy and thermogravimetric analysis. The scanning electron microscopy characterized the morphology and microstructure of the prepared sensors, and the electrochemical effective surface areas of the prepared sensors were also calculated by chronocoulometry method. The electrochemical behavior of lobetyolin on the magnetic functionalized reduced graphene oxide/Nafion nanohybrid modified glassy carbon electrode was investigated by cyclic voltammetry and differential pulse voltammetry in a phosphate buffer solution of pH 6.0. The electron-transfer coefficient (α), electron transfer number (n), and electrode reaction rate constant (Κs) were calculated as 0.78, 0.73, and 4.63 s{sup −1}, respectively. Under the optimized conditions, the sensor based on magnetic functionalized reduced graphene oxide/Nafion showed a linear voltammetric response to the lobetyolin concentration at 1.0 × 10{sup −7} to 1.0 × 10{sup −4} mol/L with detection limit (S/N = 3)of 4.3 × 10{sup −8} mol/L. The proposed sensor also displayed acceptable reproducibility, long-term stability, and high selectivity, and performs well for analysis of lobetyolin in real samples. The voltammetric sensor was successfully applied to detect lobetyolin in Codonopsis pilosula with recovery values in the range of 96.12% –102.66%. - Graphical abstract: Schematic diagram of the synthesis of MrGO hybrid and the fabrication process of the MrGO/Nafion/GCE for determination of lobetyolin. Display Omitted - Highlights: • The MrGO/Nafion@GCE electrochemical sensor was successfully fabricated. • The prepared MrGO was characterized by AFM, XRD, FTIR, VSM, TEM and SEM.

  1. Reversible Compositional Control of Oxide Surfaces by Electrochemical Potentials

    KAUST Repository

    Mutoro, Eva

    2012-01-05

    Perovskite oxides can exhibit a wide range of interesting characteristics such as being catalytically active and electronically/ionically conducting, and thus, they have been used in a number of solid-state devices such as solid oxide fuel cells (SOFCs) and sensors. As the surface compositions of perovskites can greatly influence the catalytic properties, knowing and controlling their surface compositions 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 compositional changes of La 0.8Sr 0.2CoO 3-δ (LSC 113), (La 0.5Sr 0.5) 2CoO 4±δ (LSC 214), and LSC 214-decorated LSC 113 films (LSC 113/214) were investigated in situ by utilizing synchrotron-based X-ray photoelectron spectroscopy (XPS), where the largest changes of surface Sr were found for the LSC 113/214 surface. These findings offer the potential of reversibly controlling the surface functionality of perovskites. © 2011 American Chemical Society.

  2. Method of making sulfur tolerant composite cermet electrodes for solid oxide electrochemical cells

    Science.gov (United States)

    Isenberg, Arnold O.

    1989-01-01

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

  3. Preparation of silver nanoparticles/graphene nanosheets as a catalyst for electrochemical oxidation of methanol

    Energy Technology Data Exchange (ETDEWEB)

    Han, Kun; Miao, Peng; Tang, Yuguo, E-mail: tangyg@sibet.ac.cn [Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Tong, Hui; Zhu, Xiaoli [Laboratory of Biosensing Technology, School of Life Sciences, Shanghai University, Shanghai 200444 (China); Liu, Tao; Cheng, Wenbo [Suzhou Institute of Biomedical Engineering and Technology, Chinese Academy of Sciences, Suzhou 215163 (China)

    2014-02-03

    In this report, silver nanoparticles (AgNPs) decorated graphene nanosheets have been prepared based on the reduction of Ag ions by hydroquinone, and their catalytic performance towards the electrochemical oxidation of methanol is investigated. The synthesis of the nano-composite is confirmed by transmission electron microscope measurements and UV-vis absorption spectra. Excellent electrocatalytic performance of the material is demonstrated by cyclic voltammograms. This material also contributes to the low peak potential of methanol oxidation compared with most of the other materials.

  4. Nitrogen-doped graphene: effect of graphite oxide precursors and nitrogen content on the electrochemical sensing properties.

    Science.gov (United States)

    Megawati, Monica; Chua, Chun Kiang; Sofer, Zdenek; Klímová, Kateřina; Pumera, Martin

    2017-06-21

    Graphene, produced via chemical methods, has been widely applied for electrochemical sensing due to its structural and electrochemical properties as well as its ease of production in large quantity. While nitrogen-doped graphenes are widely studied materials, the literature showing an effect of graphene oxide preparation methods on nitrogen quantity and chemical states as well as on defects and, in turn, on electrochemical sensing is non-existent. In this study, the properties of nitrogen-doped graphene materials, prepared via hydrothermal synthesis using graphite oxide produced by various classical methods using permanganate or chlorate oxidants Staudenmaier, Hummers, Hofmann and Brodie oxidation methods, were studied; the resulting nitrogen-doped graphene oxides were labeled as ST-GO, HU-GO, HO-GO and BR-GO, respectively. The electrochemical oxidation of biomolecules, such as ascorbic acid, uric acid, dopamine, nicotinamide adenine nucleotide and DNA free bases, was carried out using cyclic voltammetry and differential pulse voltammetry techniques. The nitrogen content in doped graphene oxides increased in the order ST-GO graphene followed this trend, as shown in the cyclic voltammograms. This is a very important finding that provides insight into the electrocatalytic effect of N-doped graphene. The nitrogen-doped graphene materials exhibited improved sensitivity over bare glassy carbon for ascorbic acid, uric acid and dopamine detection. These studies will enhance our understanding of the effects of graphite oxide precursors on the electrochemical sensing properties of nitrogen-doped graphene materials.

  5. Direct electrochemical reduction of solid uranium oxide in molten fluoride salts

    Science.gov (United States)

    Gibilaro, Mathieu; Cassayre, Laurent; Lemoine, Olivier; Massot, Laurent; Dugne, Olivier; Malmbeck, Rikard; Chamelot, Pierre

    2011-07-01

    The direct electrochemical reduction of UO 2 solid pellets was carried out in LiF-CaF 2 (+2 mass.% Li 2O) at 850 °C. An inert gold anode was used instead of the usual reactive sacrificial carbon anode. In this case, oxidation of oxide ions present in the melt yields O 2 gas evolution on the anode. Electrochemical characterisations of UO 2 pellets were performed by linear sweep voltammetry at 10 mV/s and reduction waves associated to oxide direct reduction were observed at a potential 150 mV more positive in comparison to the solvent reduction. Subsequent, galvanostatic electrolyses runs were carried out and products were characterised by SEM-EDX, EPMA/WDS, XRD and microhardness measurements. In one of the runs, uranium oxide was partially reduced and three phases were observed: nonreduced UO 2 in the centre, pure metallic uranium on the external layer and an intermediate phase representing the initial stage of reduction taking place at the grain boundaries. In another run, the UO 2 sample was fully reduced. Due to oxygen removal, the U matrix had a typical coral-like structure which is characteristic of the pattern observed after the electroreduction of solid oxides.

  6. Structures and electrochemical performances of pyrolized carbons from graphite oxides for electric double-layer capacitor

    Science.gov (United States)

    Kim, Ick-Jun; Yang, Sunhye; Jeon, Min-Je; Moon, Seong-In; Kim, Hyun-Soo; Lee, Yoon-Pyo; An, Kye-Hyeok; Lee, Young-Hee

    The structural features and the electrochemical performances of pyrolized needle cokes from oxidized cokes are examined and compared with those of KOH-activated needle coke. The structure of needle coke is changed to a single phase of graphite oxide after oxidation treatment with an acidic solution having an NaClO 3/needle coke composition ratio of above 7.5, and the inter-layer distance of the oxidized needle coke is expanded to 6.9 Å with increasing oxygen content. After heating at 200 °C, the oxidized needle coke is reduced to a graphite structure with an inter-layer distance of 3.6 Å. By contrast, a change in the inter-layer distance in KOH-activated needle coke is not observed. An intercalation of pyrolized needle coke, observed on first charge, occurs at 1.0 V. This value is lower than that of KOH-activation needle coke. A capacitor using pyrolized needle coke exhibits a lower internal resistance of 0.57 Ω in 1 kHz, and a larger capacitance per weight and volume of 30.3 F g -1 and 26.9 F ml -1, in the two-electrode system over the potential range 0-2.5 V compared with those of a capacitor using KOH-activation of needle coke. This better electrochemical performance is attributed to a distorted graphene layer structure derived from the process of the inter-layer expansion and shrinkage.

  7. Electrochemical and Spectroscopic Study of Mononuclear Ruthenium Water Oxidation Catalysts: A Combined Experimental and Theoretical Investigation

    KAUST Repository

    de Ruiter, J. M.

    2016-09-20

    One of the key challenges in designing light-driven artificial photosynthesis devices is the optimization of the catalytic water oxidation process. For this optimization it is crucial to establish the catalytic mechanism and the intermediates of the catalytic cycle, yet a full description is often difficult to obtain using only experimental data. Here we consider a series of mononuclear ruthenium water oxidation catalysts of the form [Ru(cy)(L)(H2O)](2+) (cy = p-cymene, L = 2,2\\'-bipyridine and its derivatives). The proposed catalytic cycle and intermediates are examined using density functional theory (DFT), radiation chemistry, spectroscopic techniques, and electrochemistry to establish the water oxidation mechanism. The stability of the catalyst is investigated using online electrochemical mass spectrometry (OLEMS). The comparison between the calculated absorption spectra of the proposed intermediates with experimental spectra, as well as free energy calculations with electrochemical data, provides strong evidence for the proposed pathway: a water oxidation catalytic cycle involving four proton-coupled electron transfer (PCET) steps. The thermodynamic bottleneck is identified as the third PCET step, which involves O-O bond formation. The good agreement between the optical and thermodynamic data and DFT predictions further confirms the general applicability of this methodology as a powerful tool in the characterization of water oxidation catalysts and for the interpretation of experimental observables.

  8. Electrochemical oxidation of 243Am(III) in nitric acid by a terpyridyl-derivatized electrode

    Energy Technology Data Exchange (ETDEWEB)

    Dares, C. J.; Lapides, A. M.; Mincher, B. J.; Meyer, T. J.

    2015-11-05

    A high surface area, tin-doped indium oxide electrode surface-derivatized with a terpyridine ligand has been applied to the oxidation of trivalent americium to Am(V) and Am(VI) in nitric acid. Potentials as low as 1.8 V vs. the saturated calomel electrode are used, 0.7 V lower than the 2.6 V potential for one-electron oxidation of Am(III) to Am(IV) in 1 M acid. This simple electrochemical procedure provides, for the first time, a method for accessing the higher oxidation states of Am in non-complexing media for developing the coordination chemistries of Am(V) and Am(VI) and, more importantly, for separation of americium from nuclear waste streams.

  9. Synthesis, characterisation and electrochemical evaluation of reduced graphene oxide modified antimony nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Silwana, Bongiwe; Horst, Charlton van der [Natural Resources and the Environment (NRE), Council for Scientific and Industrial Research (CSIR), Stellenbosch 7600 (South Africa); SensorLab, Department of Chemistry, University of the Western Cape, Bellville 7535 (South Africa); Iwuoha, Emmanuel [SensorLab, Department of Chemistry, University of the Western Cape, Bellville 7535 (South Africa); Somerset, Vernon, E-mail: vsomerset@csir.co.za [Natural Resources and the Environment (NRE), Council for Scientific and Industrial Research (CSIR), Stellenbosch 7600 (South Africa)

    2015-10-01

    This paper demonstrates some aspects on the synthesis and characterisation of nanoparticles of metallic alloys using polyvinyl alcohol as a stabiliser, which combines high surface area and superior hybrid properties. The present experimental design was to synthesise a nanocomposite of reduced graphene oxide and antimony nanoparticles to be used as thin films for macro- and micro-carbon electrodes for enhancing sensing of different toxic metal pollutants in the environment. The synthetic process of reduced graphene oxide was done using the modified Hummers method while antimony pentachloride was reduced with sodium borohydride into nanoparticles of antimony using polyvinyl-alcohol as a stabiliser. The systematic investigation of morphology was done by scanning electron microscopy and high resolution-transmission electron microscope, which revealed the synthesis of a product, consists of reduced graphene oxide antimony nanoparticles. The electrochemical behaviour of the reduced graphene oxide antimony nanoparticles coated on a glassy carbon electrode was performed using voltammetric and impedance techniques. Electrochemical impedance measurements showed that the overall resistance, including the charge–transfer resistance, was smaller with reduced graphene oxide antimony nanoparticles than reduced graphene oxide and antimony nanoparticles, on their own. Evaluation of the reduced graphene oxide antimony nanoparticle sensor in the stripping voltammetry has shown a linear working range for concentration of platinum (II) between 6.0 × 10{sup −6}–5.4 × 10{sup −5} μg L{sup −1} with limit of detection of 6 × 10{sup −6} μg L{sup −1} (signal-to-noise ratio = 3), which is below the World Health Organisation guidelines for freshwater. - Highlights: • Reduced graphene oxide modified antimony nanoparticles were chemically synthesised. • TEM results show rGO-Sb nanoparticles with a diameter range of between 2 and 20 nm. • Impedance results confirm

  10. Preparation and electrochemical performances of nanoporous/cracked cobalt oxide layer for supercapacitors

    Science.gov (United States)

    Gobal, Fereydoon; Faraji, Masoud

    2014-12-01

    Nanoporous/cracked structures of cobalt oxide (Co3O4) electrodes were successfully fabricated by electroplating of zinc-cobalt onto previously formed TiO2 nanotubes by anodizing of titanium, leaching of zinc in a concentrated alkaline solution and followed by drying and annealing at 400 °C. The structure and morphology of the obtained Co3O4 electrodes were characterized by X-ray diffraction, EDX analysis and scanning electron microscopy. The results showed that the obtained Co3O4 electrodes were composed of the nanoporous/cracked structures with an average pore size of about 100 nm. The electrochemical capacitive behaviors of the nanoporous Co3O4 electrodes were investigated by cyclic voltammetry, galvanostatic charge-discharge studies and electrochemical impedance spectroscopy in 1 M NaOH solution. The electrochemical data demonstrated that the electrodes display good capacitive behavior with a specific capacitance of 430 F g-1 at a current density of 1.0 A g-1 and specific capacitance retention of ca. 80 % after 10 days of being used in electrochemical experiments, indicating to be promising electroactive materials for supercapacitors. Furthermore, in comparison with electrodes prepared by simple cathodic deposition of cobalt onto TiO2 nanotubes(without dealloying procedure), the impedance studies showed improved performances likely due to nanoporous/cracked structures of electrodes fabricated by dealloying of zinc, which provide fast ion and electron transfer routes and large reaction surface area with the ensued fast reaction kinetics.

  11. Electrochemical Energy Storage Applications of CVD Grown Niobium Oxide Thin Films.

    Science.gov (United States)

    Fiz, Raquel; Appel, Linus; Gutiérrez-Pardo, Antonio; Ramírez-Rico, Joaquín; Mathur, Sanjay

    2016-08-24

    We report here on the controlled synthesis, characterization, and electrochemical properties of different polymorphs of niobium pentoxide grown by CVD of new single-source precursors. Nb2O5 films deposited at different temperatures showed systematic phase evolution from low-temperature tetragonal (TT-Nb2O5, T-Nb2O5) to high temperature monoclinic modifications (H-Nb2O5). Optimization of the precursor flux and substrate temperature enabled phase-selective growth of Nb2O5 nanorods and films on conductive mesoporous biomorphic carbon matrices (BioC). Nb2O5 thin films deposited on monolithic BioC scaffolds produced composite materials integrating the high surface area and conductivity of the carbonaceous matrix with the intrinsically high capacitance of nanostructured niobium oxide. Heterojunctions in Nb2O5/BioC composites were found to be beneficial in electrochemical capacitance. Electrochemical characterization of Nb2O5/BioC composites showed that small amounts of Nb2O5 (as low as 5%) in conjunction with BioCarbon resulted in a 7-fold increase in the electrode capacitance, from 15 to 104 F g(-1), while imparting good cycling stability, making these materials ideally suited for electrochemical energy storage applications.

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

    International Nuclear Information System (INIS)

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

    2007-01-01

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

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

    Science.gov (United States)

    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.

  14. Coupling ultraviolet light and ultrasound irradiation with Conductive-Diamond Electrochemical Oxidation for the removal of progesterone

    International Nuclear Information System (INIS)

    Vidales, María J. Martín de; Barba, Silvia; Sáez, Cristina; Cañizares, Pablo; Rodrigo, Manuel A.

    2014-01-01

    Highlights: • Single sonolysis and photolysis technologies entail a slight progesterone removal and nil mineralization. • Synergistic effects of irradiating UV light and US are clearly observed in the oxidation rate. • The energy required by CDSEO and CDSPEO prevents against their application. • CDSEO mainly favors the mass transfer of organics to the conductive-diamond surface. • CDPEO promotes the formation of radicals in the bulk solution. - Abstract: This work focusses on the improvement of the efficiency of Conductive Diamond Electrochemical Oxidation (CDEO) by coupling US and UV irradiation in the degradation of progesterone from wastewater. Results show that CDEO is a promising technology for the degradation of progesterone, just the opposite of that observed for single sonolysis and photolysis technologies, which only entail a slight removal of progesterone and nil mineralization. Coupling UV light and US irradiations with CDEO seems to have a very positive effect, improving results obtained by single CDEO very significantly. Conductive Diamond Sono Electrochemical Oxidation (CDSEO) mainly seems to improve the transfer of pollutants to the conductive-diamond surface, while Conductive Diamond Photo Electrochemical Oxidation (CDPEO) seems to promote the formation of radicals from oxidants produced electrochemically. Soft oxidation conditions are obtained with the single application of both irradiation technologies, whereas an efficient mineralization is attained with CDEO, CDSEO, CDPEO and Conductive Diamond Sono-Photo Electrochemical Oxidation (CDSPEO). However, the high energy demands of US irradiation technologies advices against the use of CDSEO and CDSPEO

  15. Enhanced activity of gold-supported cobalt oxide for the electrochemical evolution of oxygen.

    Science.gov (United States)

    Yeo, Boon Siang; Bell, Alexis T

    2011-04-13

    Scanning electron microscopy, linear sweep voltammetry, chronoamperometry, and in situ surface-enhanced Raman spectroscopy were used to investigate the electrochemical oxygen evolution reaction (OER) occurring on cobalt oxide films deposited on Au and other metal substrates. All experiments were carried out in 0.1 M KOH. A remarkable finding is that the turnover frequency for the OER exhibited by ∼0.4 ML of cobalt oxide deposited on Au is 40 times higher than that of bulk cobalt oxide. The activity of small amounts of cobalt oxide deposited on Pt, Pd, Cu, and Co decreased monotonically in the order Au > Pt > Pd > Cu > Co, paralleling the decreasing electronegativity of the substrate metal. Another notable finding is that the OER turnover frequency for ∼0.4 ML of cobalt oxide deposited on Au is nearly three times higher than that for bulk Ir. Raman spectroscopy revealed that the as-deposited cobalt oxide is present as Co(3)O(4) but undergoes progressive oxidation to CoO(OH) with increasing anodic potential. The higher OER activity of cobalt oxide deposited on Au is attributed to an increase in fraction of the Co sites present as Co(IV) cations, a state of cobalt believed to be essential for OER to occur. A hypothesis for how Co(IV) cations contribute to OER is proposed and discussed. © 2011 American Chemical Society

  16. Boron doped ZnO embedded into reduced graphene oxide for electrochemical supercapacitors

    Science.gov (United States)

    Alver, Ü.; Tanrıverdi, A.

    2016-08-01

    In this work, reduced graphene oxide/boron doped zinc oxide (RGO/ZnO:B) composites were fabricated by a hydrothermal process and their electrochemical properties were investigated as a function of dopant concentration. First, boron doped ZnO (ZnO:B) particles was fabricated with different boron concentrations (5, 10, 15 and 20 wt%) and then ZnO:B particles were embedded into RGO sheets. The physical properties of sensitized composites were characterized by XRD and SEM. Characterization indicated that the ZnO:B particles with plate-like structure in the composite were dispersed on graphene sheets. The electrochemical properties of the RGO/ZnO:B composite were investigated through cyclic voltammetry, galvanostatic charge/discharge measurements in a 6 M KOH electrolyte. Electrochemical measurements show that the specific capacitance values of RGO/ZnO:B electrodes increase with increasing boron concentration. RGO/ZnO:B composite electrodes (20 wt% B) display the specific capacitance as high as 230.50 F/g at 5 mV/s, which is almost five times higher than that of RGO/ZnO (52.71 F/g).

  17. Surface Properties of PAN-based Carbon Fibers Modified by Electrochemical Oxidization in Organic Electrolyte Systems

    Directory of Open Access Journals (Sweden)

    WU Bo

    2016-09-01

    Full Text Available PAN-based carbon fibers were modified by electrochemical oxidization using fatty alcohol polyoxyethylene ether phosphate (O3P, triethanolamine (TEOA and fatty alcohol polyoxyethylene ether ammonium phosphate (O3PNH4 as organic electrolyte respectively. Titration analysis, single fiber fracture strength measurement and field emission scanning electron microscopy (FE-SEM were used to evaluate the content of acidic functional group on the surface, mechanical properties and surface morphology of carbon fiber. The optimum process of electrochemical treatment obtained is at 50℃ for 2min and O3PNH4 (5%, mass fraction as the electrolyte with current density of 2A/g. In addition, the surface properties of modified carbon fibers were characterized by X-ray photoelectron spectroscopy (XPS and single fiber contact angle test. The results show that the hydrophilic acidic functional groups on the surface of carbon fiber which can enhance the surface energy are increased by the electrochemical oxidation using O3PNH4 as electrolyte, almost without any weakening to the mechanical properties of carbon fiber.

  18. Crystal size effect on the electrochemical oxidation of formate on carbon-supported palladium nanoparticles

    International Nuclear Information System (INIS)

    Santos, Rayana Marcela Izidoro da Silva; Nakazato, Roberto Zenhei; Ciapina, Eduardo Goncalves

    2016-01-01

    Full text: The electrochemical oxidation of formate in alkaline electrolytes has emerged an a promising anodic reaction in the Direct Formate Fuel Cells[1]. Although palladium is considered to be one of the best electro catalyst for the oxidation of formate, important structure-activity relationships are still not understood. In the present work, we investigated the effect of the size of the palladium crystals in the electrochemical oxidation of formate in 0.1 mol L -1 KOH. Carbon-supported palladium nanoparticles (Pd/C) were prepared by chemical reduction of palladium (II) chloride in aqueous media by sodium borohydride in the presence of varying quantities of sodium citrate in the reaction media to obtain metallic crystals with distinct sizes. Analysis of the X-ray diffraction profile revealed the presence of palladium crystals in the range of 6 to 19 nm. Potentiostatic oxidation of formate on the distinct Pd/C samples revealed a volcano-like dependence of the specific activity with the size of the palladium crystals, presenting the highest activity for crystals around 7.5 nm. Reference: [1] A.M. Bartrom, J.L. Haan, The direct formate fuel cell with an alkaline anion exchange membrane, J. Power Sources. 214 (2012) 68-74. (author)

  19. The cooperative electrochemical oxidation of chlorophenols in anode-cathode compartments

    International Nuclear Information System (INIS)

    Wang Hui; Wang Jianlong

    2008-01-01

    By using a self-made carbon/polytetrafluoroethylene (C/PTFE) O 2 -fed as the cathode and Ti/IrO 2 /RuO 2 as the anode, the degradation of three organic compounds (phenol, 4-chlorophenol, and 2,4-dichlorophenol) was investigated in the diaphragm (with terylene as diaphragm material) electrolysis device by electrochemical oxidation process. The result indicated that the concentration of hydrogen peroxide (H 2 O 2 ) was 8.3 mg/L, and hydroxyl radical (HO·) was determined in the cathodic compartment by electron spin resonance spectrum (ESR). The removal efficiency for organic compounds reached about 90% after 120 min, conforming to the sequence of phenol, 4-chlorophenol, and 2,4-dichlorophenol. And the dechlorination degree of 4-chlorophenol exceeded 90% after 80 min. For H 2 O 2 , HO· existed in the catholyte and reduction dechlorination at the cathode, the mineralization of organics in the cathodic compartment was better than that in the anodic compartment. The degradation of organics was supposed to be cooperative oxidation by direct or indirect electrochemical oxidation at the anode and H 2 O 2 , HO· produced by oxygen reduction at the cathode. High-performance liquid chromatography (HPLC) allowed identifying phenol as the dechlorination product of 4-chlorophenol in the cathodic compartment, and hydroquinone, 4-chlorocatechol, benzoquinone, maleic, fumaric, oxalic, and formic acids as the main oxidation intermediates in the cathodic and anodic compartments. A reaction scheme involving all these intermediates was proposed

  20. The electrochemical transfer reactions and the structure of the iron|oxide layer|electrolyte interface

    International Nuclear Information System (INIS)

    Petrović, Željka; Metikoš-Huković, Mirjana; Babić, Ranko

    2012-01-01

    The thickness, barrier (protecting) and semiconducting properties of the potentiostatically formed oxide films on the pure iron electrode in an aqueous borate buffer solution were investigated by electrochemical quartz crystal nanobalance (EQCN), electrochemical impedance spectroscopy (EIS), and Mott–Schottky (MS) analysis. The thicknesses of the prepassive Fe(II)hydroxide layer (up to monolayer) nucleated on the bare iron surface and the passive Fe(II)/Fe(III) layer (up to 2 nm), deposited on the top of the first one, were determined using in situ gravimetry. Electronic properties of iron prepassive and passive films as well as ionic and electronic transfer reactions at the film|solution interface were discussed on the basis of a band structure model of the surface oxide film and the potential distribution at the interface. The anodic oxide film formation and cathodic decomposition are coupled processes and their reversible inter-conversion is mediated by the availability of free charge carriers on the electrode|solution interface. The structure of the reversible double layer at the iron oxide|solution interface was discussed based on the concept of the specific adsorption of the imidazolium cation on the negatively charged electrode surface at pH > pH pzc .

  1. Electrochemical Water Oxidation by a Catalyst-Modified Metal-Organic Framework Thin Film

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Shaoyang; Pineda-Galvan, Yuliana; Maza, William A.; Epley, Charity C.; Zhu, Jie; Kessinger, Matthew C.; Pushkar, Yulia; Morris, Amanda J. (VP); (Purdue)

    2016-12-15

    Water oxidation, a key component in artificial photosynthesis, requires high overpotentials and exhibits slow reaction kinetics that necessitates the use of stable and efficient heterogeneous water-oxidation catalysts (WOCs). Here, we report the synthesis of UiO-67 metal–organic framework (MOF) thin films doped with [Ru(tpy)(dcbpy)OH2]2+ (tpy=2,2':6',2''-terpyridine, dcbpy=5,5'-dicarboxy-2,2'-bipyridine) on conducting surfaces and their propensity for electrochemical water oxidation. The electrocatalyst oxidized water with a turnover frequency (TOF) of (0.2±0.1) s-1 at 1.71 V versus the normal hydrogen electrode (NHE) in buffered solution (pH~7) and exhibited structural and electrochemical stability. The electroactive sites were distributed throughout the MOF thin film on the basis of scan-ratedependent voltammetry studies. This work demonstrates a promising way to immobilize large concentrations of electroactive WOCs into a highly robust MOF scaffold and paves the way for future photoelectrochemical water-splitting systems.

  2. Electrochemical sensing of glucose by reduced graphene oxide-zinc ferrospinels

    Energy Technology Data Exchange (ETDEWEB)

    Shahnavaz, Zohreh, E-mail: zohreh.shahnavaz@siswa.um.edu.my [Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Woi, Pei Meng, E-mail: pmwoi@um.edu.my [Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Center of Ionic Liquids, University of Malaya, 50603 Kuala Lumpur (Malaysia); Alias, Yatimah, E-mail: yatimah70@um.edu.my [Department of Chemistry, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Center of Ionic Liquids, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2016-08-30

    Highlights: • A facile in situ hydrothermal method for ZnFe{sub 2}O{sub 4} nanoparticles incorporation into graphene oxide sheets. • Excellent selectivity, reproducibility and stability properties compared to others Zn-based glucose sensor. • Amount of reduced graphene oxide directly affected the electro-catalytic activity of ZnFe{sub 2}O{sub 4}/rGO nanocomposite towards glucose detection. - Abstract: We have developed ZnFe{sub 2}O{sub 4} magnetic nanoparticles/reduced graphene oxide nanosheets modified glassy carbon (ZnFe{sub 2}O{sub 4}/rGO/GCE) electrode as a novel system for the electrochemical glucose sensing. Via a facile in situ hydrothermal route, the reduction of GO and the formation of ZnFe{sub 2}O{sub 4} nanoparticles occurred simultaneously. This enables the ZnFe{sub 2}O{sub 4} nanoparticles dispersed on the reduced graphene sheet. Characterization of nanocomposite by X-ray diffraction (XRD) and transmission electron microscopy (TEM) clearly demonstrate the successful attachment of ZnFe{sub 2}O{sub 4} nanoparticles to graphene sheets. Electrochemical studies revealed that the ZnFe{sub 2}O{sub 4}/rGO/GCE possess excellent electrocatalytic activities toward the oxidation of glucose and the performance of sensor is enhanced by integration of graphene nanosheets with ZnFe{sub 2}O{sub 4} nanoparticles.

  3. Electrochemical Oxidation of Sulfamethazine on Multi-Walled Nanotube Film Coated Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    L. Fotouhi

    2014-04-01

    Full Text Available The electrochemical oxidation of sulfamethazine (SMZ has been studied at a multi-walled carbon nanotubes modified glassy carbon electrode (MWCNT-GCE by cyclic voltammetry. This modified electrode (MWCNT-GCE exhibited excellent electrocatalytic behavior toward the oxidation of SMZ as evidenced by the enhancement of the oxidation peak current and the shift in the anodic potential to less positive values (170 mV in comparison with the bare GCE. The formal potential, E0', of SMZ is pH dependent with a slope of 54 mV per unit of pH, close to the anticipated Nerstian value of 59 mV for a 2-electron and 2-proton oxidation process. A detailed analysis of cyclic voltammograms gave fundamental electrochemical parameters including the electroactive surface coverage (Г, the transfer coefficient (a, the heterogeneous rate constant (ks. Under the selected conditions, the peak current shows two dynamic linear ranges of 10-200 mM and 300-3000 mM with the detection limit of 6.1 mM. The method was successfully applied to analyze SMZ in serum sample

  4. Electrochemical oxidation of drug residues in water by the example of tetracycline, gentamicin and Aspirin {sup trademark}

    Energy Technology Data Exchange (ETDEWEB)

    Weichgrebe, D.; Danilova, E.; Rosenwinkel, K.H. [Inst. of Water Quality and Waste Management, Univ. of Hannover, Hannover (Germany); Vedenjapin, A.; Baturova, M. [Inst. of Organic Chemistry, Russian Academy of Science, Moscow (Russian Federation)

    2003-07-01

    The electrochemical oxidation as a method to destroy drug residues like Aspirin {sup trademark}, tetracycline or gentamicin in water was investigated with C-Anode (modified by manganese oxides) and Pt Anode. The mechanism of Aspirin {sup trademark} and tetracycline oxidation and the influence of the biocide effect was observed using GC-MS and three different microbiological tests. In general the biological availability increases with progressive oxidation of the antibiotics. (orig.)

  5. Electrochemical Water Oxidation and Stereoselective Oxygen Atom Transfer Mediated by a Copper Complex.

    Science.gov (United States)

    Kafentzi, Maria-Chrysanthi; Papadakis, Raffaello; Gennarini, Federica; Kochem, Amélie; Iranzo, Olga; Le Mest, Yves; Le Poul, Nicolas; Tron, Thierry; Faure, Bruno; Simaan, A Jalila; Réglier, Marius

    2018-04-06

    Water oxidation by copper-based complexes to form dioxygen has attracted attention in recent years, with the aim of developing efficient and cheap catalysts for chemical energy storage. In addition, high-valent metal-oxo species produced by the oxidation of metal complexes in the presence of water can be used to achieve substrate oxygenation with the use of H 2 O as an oxygen source. To date, this strategy has not been reported for copper complexes. Herein, a copper(II) complex, [(RPY2)Cu(OTf) 2 ] (RPY2=N-substituted bis[2-pyridyl(ethylamine)] ligands; R=indane; OTf=triflate), is used. This complex, which contains an oxidizable substrate moiety (indane), is used as a tool to monitor an intramolecular oxygen atom transfer reaction. Electrochemical properties were investigated and, upon electrolysis at 1.30 V versus a normal hydrogen electrode (NHE), both dioxygen production and oxygenation of the indane moiety were observed. The ligand was oxidized in a highly diastereoselective manner, which indicated that the observed reactivity was mediated by metal-centered reactive species. The pH dependence of the reactivity was monitored and correlated with speciation deduced from different techniques, ranging from potentiometric titrations to spectroscopic studies and DFT calculations. Water oxidation for dioxygen production occurs at neutral pH and is probably mediated by the oxidation of a mononuclear copper(II) precursor. It is achieved with a rather low overpotential (280 mV at pH 7), although with limited efficiency. On the other hand, oxygenation is maximum at pH 8-8.5 and is probably mediated by the electrochemical oxidation of an antiferromagnetically coupled dinuclear bis(μ-hydroxo) copper(II) precursor. This constitutes the first example of copper-centered oxidative water activation for a selective oxygenation reaction. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Preparation and Characterization of a PEDOT-Manganese Oxide Composite, and Its Application to Electrochemical Sensing

    International Nuclear Information System (INIS)

    Arena, A.

    2016-01-01

    Stable and transparent aqueous dispersions of a hybrid organic-inorganic composite, are prepared by electrochemically doping Manganese Oxide into Polyethylendioxythiophene (PEDOT). Films deposited from the PEDOT-MnOx dispersions, are characterized by means of electrical and optical measurements, and by means of Atomic Force Microscopy (AFM) investigations. The PEDOT-MnOx composite is then used to modify one of the gold electrodes of a simple electrochemical cell, in which Nafion is used as a solid electrolyte. The cell is characterized using time domain electrical measurements. It is found that distinguishable redox peaks arise in the current-voltage loops of the cell, as nanomolar amounts of either acetic acid and ammonia, are added to the deionized water into which the cell is immersed. The intensity of such current peaks, is linearly related to the concentration of the analytes, in the nanomolar range of concentrations. (paper)

  7. Direct versus indirect electrochemical oxidation of pesticide polluted drainage water containing sodium chloride

    DEFF Research Database (Denmark)

    Muff, Jens; Erichsen, Rasmus; Damgaard, Christian

    2008-01-01

    the treatment. Indirect electrochemical treatment, where a highly oxidized brine solution was added to the drainage water, revealed immediately reduction in COD, and similar to the direct treatment, degradation of all of the pesticide pollutants was obtained except for the O,O,O-triethyl-phosphoric acid......Drainage water from a depot of chemical waste, polluted with a mixture of organophosphates and degradation products was treated by a direct as well as an indirect electrochemical method using a Ti/Pt-Ir anode and Stainless Steel 304 cathode. With a concentration of 0.7%, sodium chloride...... concentrations. Analyses of the actual pollutants, Me-Parathion, parathion, malathion and degradation products, confirmed that the concentrations of all initial pollutants were eliminated during the treatment. The only exception was O,O,O-triethyl-phosphoric acid, a degradation product which was formed during...

  8. Direct versus indirect electrochemical oxidation of pesticide polluted drainage water containing sodium chloride

    DEFF Research Database (Denmark)

    Muff, Jens; Erichsen, Rasmus; Damgaard, Christian

    2008-01-01

    Drainage water from a depot of chemical waste, polluted with a mixture of organophosphates and degradation products was treated by a direct as well as an indirect electrochemical method using a Ti/Pt-Ir anode and Stainless Steel 304 cathode. With a concentration of 0.7%, sodium chloride...... the treatment. Indirect electrochemical treatment, where a highly oxidized brine solution was added to the drainage water, revealed immediately reduction in COD, and similar to the direct treatment, degradation of all of the pesticide pollutants was obtained except for the O,O,O-triethyl-phosphoric acid...... concentrations. Analyses of the actual pollutants, Me-Parathion, parathion, malathion and degradation products, confirmed that the concentrations of all initial pollutants were eliminated during the treatment. The only exception was O,O,O-triethyl-phosphoric acid, a degradation product which was formed during...

  9. Electrochemical behavior of thin anodic oxide films on Zircaloy-4: Role of the mobile defects

    International Nuclear Information System (INIS)

    Salot, R.; Lefebvre-Joud, F.; Baroux, B.

    1996-01-01

    The first stages of the electrochemical oxidation of Zircaloy-4 are investigated using simple electrochemical tests and modeling the passive film modifications occurring as a result of contact with the electrolyte. Variations in electrode potential (open-circuit conditions) or current density (potentiodynamic scans) can be simply explained by a high field (F ∼ 10 6 V/cm) assisted passive film growth. Under open-circuit conditions, this field does not vary with exposure time (in the 2 h to 48 h range). The minimum electric field for the onset of high-field behavior is also evaluated and found smaller than the theoretical value which can be explained by a variation in the concentration of mobile defects throughout the film. Measurements of the electrode potential decay after a potentiodynamic scan confirm this model, allowing interpretation of the film modification as a combination of two separate phenomena: film growth under a high electric field and point defect annihilation

  10. Amplified electrochemical determination of maltol in food based on graphene oxide-wrapped tin oxide@carbon nanospheres.

    Science.gov (United States)

    Gan, Tian; Sun, Junyong; Yu, Miaomiao; Wang, Kaili; Lv, Zhen; Liu, Yanming

    2017-01-01

    The study presents a new approach for rapid and ultrasensitive detection of maltol using a glassy carbon electrode (GCE) modified with graphene oxide-wrapped tin oxide@carbon nanospheres (SnO2@C@GO). The morphological and components properties of SnO2@C@GO nanocomposites were investigated by means of X-ray diffraction spectroscopy, Raman spectroscopy, field emission scanning electron microscopy, high resolution transmission electron microscopy, and electrochemical impedance spectroscopy. SnO2@C@GO nanocomposite on a GCE had a synergetic effect on the electrochemical oxidation of maltol by means of square wave voltammetry. Under the optimum conditions, anodic peak current response of maltol was linear with its concentration in the range of 80nM-10μM, and a detection limit of 12nM was achieved for maltol. The experiment results presented that the method showed good selectivity, sensitivity, reproducibility, and long-term stability, as well as excellent potential for use as an ideal inexpensive voltammetric method applicable for complex food matrices. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Morphology, structural and optical properties of iron oxide thin film photoanodes in photoelectrochemical cell: Effect of electrochemical oxidation

    Science.gov (United States)

    Maabong, Kelebogile; Machatine, Augusto G.; Hu, Yelin; Braun, Artur; Nambala, Fred J.; Diale, Mmantsae

    2016-01-01

    Hematite (α-Fe2O3) is a promising semiconductor as photoanode in solar hydrogen production from photoelectrolysis of water due to its appropriate band gap, low cost and high electrochemical stability in aqueous caustic electrolytes. Operation of such photoanode in a biased photoelectrochemical cell constitutes an anodization with consequent redox reactions at the electrode surface. α-Fe2O3 thin film photoanodes were prepared by simple and inexpensive dip coating method on fluorine doped tin oxide (FTO) glass substrate, annealed in air at 500 °C for 2 h, then electrochemically oxidized (anodized) in 1 M KOH at 500 mV for 1 min in dark and light conditions. Changes in structural properties and morphology of α-Fe2O3 nanoparticles films were investigated by XRD, Raman spectroscopy and a high resolution FE-SEM. The average grain size was observed to increase from 57 nm for pristine samples to 73 and 77 nm for anodized samples in dark and light respectively. Broadening and red shift in Raman spectra in anodized samples may be attributed to lattice expansion upon oxidation. The UV-visible measurements revealed enhanced absorption in the photoanodes after the treatment. The findings suggest that the anodization of the photoelectrode in a biased cell causes not only changes of the molecular structure at the surface, but also changes in the crystallographic structure which can be detected with x-ray diffractometry.

  12. Morphology, structural and optical properties of iron oxide thin film photoanodes in photoelectrochemical cell: Effect of electrochemical oxidation

    International Nuclear Information System (INIS)

    Maabong, Kelebogile; Machatine, Augusto G.; Hu, Yelin; Braun, Artur; Nambala, Fred J.; Diale, Mmantsae

    2016-01-01

    Hematite (α-Fe_2O_3) is a promising semiconductor as photoanode in solar hydrogen production from photoelectrolysis of water due to its appropriate band gap, low cost and high electrochemical stability in aqueous caustic electrolytes. Operation of such photoanode in a biased photoelectrochemical cell constitutes an anodization with consequent redox reactions at the electrode surface. α-Fe_2O_3 thin film photoanodes were prepared by simple and inexpensive dip coating method on fluorine doped tin oxide (FTO) glass substrate, annealed in air at 500 °C for 2 h, then electrochemically oxidized (anodized) in 1 M KOH at 500 mV for 1 min in dark and light conditions. Changes in structural properties and morphology of α-Fe_2O_3 nanoparticles films were investigated by XRD, Raman spectroscopy and a high resolution FE-SEM. The average grain size was observed to increase from ~57 nm for pristine samples to 73 and 77 nm for anodized samples in dark and light respectively. Broadening and red shift in Raman spectra in anodized samples may be attributed to lattice expansion upon oxidation. The UV–visible measurements revealed enhanced absorption in the photoanodes after the treatment. The findings suggest that the anodization of the photoelectrode in a biased cell causes not only changes of the molecular structure at the surface, but also changes in the crystallographic structure which can be detected with x-ray diffractometry.

  13. Morphology, structural and optical properties of iron oxide thin film photoanodes in photoelectrochemical cell: Effect of electrochemical oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Maabong, Kelebogile [Department of Physics, University of Pretoria, Pretoria 0002 (South Africa); Laboratory of High Ceramics, Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf (Switzerland); Department of Physics, University of Botswana, Private Bag 002, Gaborone (Botswana); Machatine, Augusto G. [Department of Physics, University of Pretoria, Pretoria 0002 (South Africa); Hu, Yelin [Laboratory of High Ceramics, Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf (Switzerland); Laboratory for Photonics and Interfaces, EPFL, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland); Braun, Artur [Laboratory of High Ceramics, Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf (Switzerland); Nambala, Fred J. [Department of Physics, University of Pretoria, Pretoria 0002 (South Africa); University of Zambia, Box 32379, Great East Road Campus, Lusaka (Zambia); Diale, Mmantsae, E-mail: mmantsae.diale@up.ac.za [Department of Physics, University of Pretoria, Pretoria 0002 (South Africa); Laboratory of High Ceramics, Empa, Swiss Federal Laboratories for Materials Science and Technology, CH-8600 Dübendorf (Switzerland)

    2016-01-01

    Hematite (α-Fe{sub 2}O{sub 3}) is a promising semiconductor as photoanode in solar hydrogen production from photoelectrolysis of water due to its appropriate band gap, low cost and high electrochemical stability in aqueous caustic electrolytes. Operation of such photoanode in a biased photoelectrochemical cell constitutes an anodization with consequent redox reactions at the electrode surface. α-Fe{sub 2}O{sub 3} thin film photoanodes were prepared by simple and inexpensive dip coating method on fluorine doped tin oxide (FTO) glass substrate, annealed in air at 500 °C for 2 h, then electrochemically oxidized (anodized) in 1 M KOH at 500 mV for 1 min in dark and light conditions. Changes in structural properties and morphology of α-Fe{sub 2}O{sub 3} nanoparticles films were investigated by XRD, Raman spectroscopy and a high resolution FE-SEM. The average grain size was observed to increase from ~57 nm for pristine samples to 73 and 77 nm for anodized samples in dark and light respectively. Broadening and red shift in Raman spectra in anodized samples may be attributed to lattice expansion upon oxidation. The UV–visible measurements revealed enhanced absorption in the photoanodes after the treatment. The findings suggest that the anodization of the photoelectrode in a biased cell causes not only changes of the molecular structure at the surface, but also changes in the crystallographic structure which can be detected with x-ray diffractometry.

  14. Behaviour of zirconium oxidation and is oxide films in alkali halide solutions as studied by electrochemical techniques

    International Nuclear Information System (INIS)

    Saleh, H.E.M.

    1996-01-01

    Study of the properties of Zr electrode and the oxide films that cover the metal surface is of extreme importance due to their wide applications in chemical and nuclear industry. In this thesis the electrochemical behaviour of Zr electrode in alkali halide solutions and with various surface conditions was studied, Also the galvanostatic oxidation of the metal in addition to the open circuit and impedance measurements were employed. Chapter I is a literature survey of the electrochemistry of Zr metal with particular emphasis on the stability and growth process of Zr in different media. Chapter II contains the experimental part, including details of the electrochemical techniques used in the measurements. The electrode impedance was always balanced as a series capacitance Cs and resistance Rs.Chapter III includes the experimental results and discussion. It is divide into sections, A and B. Section A includes the results of some experimental parameters which affect the reactivity of the oxide growth process on the zirconium surface, such as surface pre - treatment, electrolyte composition, the effect of different alkali halide anions, as well as the triiodide ion. 9 tabs.,26 figs.,67 refs

  15. Investigation of the direct and indirect electrochemical oxidation of hydrazine in nitric acid medium on platinum

    International Nuclear Information System (INIS)

    Cames, B.

    1997-01-01

    In nuclear fuel processing by the PUREX process, the purification of plutonium in nitric acid medium requires the oxidation of Pu(III) to Pu(IV), and of hydrazinium nitrate to nitrogen. The study helped to characterize the electrochemical behavior of the oxidation of hydrazinium nitrate and the reduction of nitric acid to nitrous acid, a compound which can chemically oxidize hydrazinium nitrate and Pu(III). Electro-analytical studies on polycrystalline platinum showed that hydrazine is oxidized in two potential zones, which depend on the surface texture of the platinum anode. Electrolysis in separate compartments, carried out in medium-acid media (2 and 4 mo/l) in the potential zone where these processes take place, showed that, at 0.9 V/ECS, the hydrazine oxidation reactions involved are: a four-electron process (75 %) with nitrogen formation and a one-electron process (25 %) with formation of nitrogen and ammonium ion. By contrast, electrolysis carried out at 0.65 V/ECS (with reactivation of the electrode at - 0.2 V/ECS to remove the poison from the platinum) allowed the selective oxidation of hydrazine to nitrogen by the four-electron reaction. Nitric acid can only be reduced to nitrous acid in the absence of hydrazine. For medium-acid media (≤ 6 mol/l), this reaction takes place at potentials below - 0.2 V/ECS. However, the production rate of nitrous acid (partial order 0 with respect to nitric acid) is very low compared with the values obtained for strongly-acid media (6 to 10 mol/l) at the potential of - 0.1 V/ECS. Note that, in concentrated nitric medium, the selectivity of the reduction reaction is 47 to 85 % for nitrous acid, depending on the nitric acid concentration (6 to 10 mol/l) and the potential imposed (- 0.1 ≤ E ≤ 0.6 V/ECS). A kinetic study helped to determine the hydrazine oxidation rates as a function of the operating conditions. In all cases, the reaction rate is of partial order 0 with respect to hydrazine. These studies accordingly

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

    Directory of Open Access Journals (Sweden)

    Teo Peik-See

    2014-08-01

    Full Text Available 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 µM, 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 µM for AA and DA, respectively.

  17. Fabrication of highly catalytic silver nanoclusters/graphene oxide nanocomposite as nanotag for sensitive electrochemical immunoassay

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jiamian; Wang, Xiuyun; Wu, Shuo, E-mail: wushuo@dlut.edu.cn; Song, Jie; Zhao, Yanqiu; Ge, Yanqiu; Meng, Changgong

    2016-02-04

    Silver nanoclusters and graphene oxide nanocomposite (AgNCs/GRO) is synthesized and functionalized with detection antibody for highly sensitive electrochemical sensing of carcinoembryonic antigen (CEA), a model tumor marker involved in many cancers. AgNCs with large surface area and abundant amount of low-coordinated sites are synthesized with DNA as template and exhibit high catalytic activity towards the electrochemical reduction of H{sub 2}O{sub 2}. GRO is employed to assemble with AgNCs because it has large specific surface area, super electronic conductivity and strong π-π stacking interaction with the hydrophobic bases of DNA, which can further improve the catalytic ability of the AgNCs. Using AgNCs/GRO as signal amplification tag, an enzyme-free electrochemical immunosensing protocol is designed for the highly sensitive detection of CEA on the capture antibody functionalized immunosensing interface. Under optimal conditions, the designed immunosensor exhibits a wide linear range from 0.1 pg mL{sup −1} to 100 ng mL{sup −1} and a low limit of detection of 0.037 pg mL{sup −1}. Practical sample analysis reveals the sensor has good accuracy and reproducibility, indicating the great application prospective of the AgNCs/GRO in fabricating highly sensitive immunosensors, which can be extended to the detection of various kinds of low abundance disease related proteins. - Highlights: • An enzyme-free electrochemical immunosensor is reported for detecting proteins. • A silver nanocluster/graphene oxide composite is synthesized as nanotag. • The nanotags exhibit highly catalytic activity to the electro-reduction of H{sub 2}O{sub 2}. • The as-fabricated immunosensor could detect protein in serum samples.

  18. Catalytic and electrochemical behaviour of solid oxide fuel cell operated with simulated-biogas mixtures

    Science.gov (United States)

    Dang-Long, T.; Quang-Tuyen, T.; Shiratori, Y.

    2016-06-01

    Being produced from organic matters of wastes (bio-wastes) through a fermentation process, biogas mainly composed of CH4 and CO2 and can be considered as a secondary energy carrier derived from solar energy. To generate electricity from biogas through the electrochemical process in fuel cells is a state-of-the-art technology possessing higher energy conversion efficiency without harmful emissions compared to combustion process in heat engines. Getting benefits from high operating temperature such as direct internal reforming ability and activation of electrochemical reactions to increase overall system efficiency, solid oxide fuel cell (SOFC) system operated with biogas becomes a promising candidate for distributed power generator for rural applications leading to reductions of environmental issues caused by greenhouse effects and bio-wastes. CO2 reforming of CH4 and electrochemical oxidation of the produced syngas (H2-CO mixture) are two main reaction processes within porous anode material of SOFC. Here catalytic and electrochemical behavior of Ni-ScSZ (scandia stabilized-zirconia) anode in the feed of CH4-CO2 mixtures as simulated-biogas at 800 °C were evaluated. The results showed that CO2 had strong influences on both reaction processes. The increase in CO2 partial pressure resulted in the decrease in anode overvoltage, although open-circuit voltage was dropped. Besides that, the simulation result based on a power-law model for equimolar CH4-CO2 mixture revealed that coking hazard could be suppressed along the fuel flow channel in both open-circuit and closed-circuit conditions.

  19. Catalytic and electrochemical behaviour of solid oxide fuel cell operated with simulated-biogas mixtures

    Energy Technology Data Exchange (ETDEWEB)

    Dang-Long, T., E-mail: 3TE14098G@kyushu-u.ac.jp [Department of Hydrogen Energy Systems, Faculty of Engineering, Kyushu University Motooka 744, Nishiku, Fukuoka, 810-0395 (Japan); Quang-Tuyen, T., E-mail: tran.tuyen.quang.314@m.kyushu-u.ac.jp [International Research Center for Hydrogen Energy, Kyushu University Motooka 744, Nishiku, Fukuoka, 810-0395 (Japan); Shiratori, Y., E-mail: shiratori.yusuke.500@m.kyushu-u.ac.jp [Department of Hydrogen Energy Systems, Faculty of Engineering, Kyushu University Motooka 744, Nishiku, Fukuoka, 810-0395 (Japan); International Research Center for Hydrogen Energy, Kyushu University Motooka 744, Nishiku, Fukuoka, 810-0395 (Japan)

    2016-06-03

    Being produced from organic matters of wastes (bio-wastes) through a fermentation process, biogas mainly composed of CH{sub 4} and CO{sub 2} and can be considered as a secondary energy carrier derived from solar energy. To generate electricity from biogas through the electrochemical process in fuel cells is a state-of-the-art technology possessing higher energy conversion efficiency without harmful emissions compared to combustion process in heat engines. Getting benefits from high operating temperature such as direct internal reforming ability and activation of electrochemical reactions to increase overall system efficiency, solid oxide fuel cell (SOFC) system operated with biogas becomes a promising candidate for distributed power generator for rural applications leading to reductions of environmental issues caused by greenhouse effects and bio-wastes. CO{sub 2} reforming of CH{sub 4} and electrochemical oxidation of the produced syngas (H{sub 2}–CO mixture) are two main reaction processes within porous anode material of SOFC. Here catalytic and electrochemical behavior of Ni-ScSZ (scandia stabilized-zirconia) anode in the feed of CH{sub 4}–CO{sub 2} mixtures as simulated-biogas at 800 °C were evaluated. The results showed that CO{sub 2} had strong influences on both reaction processes. The increase in CO{sub 2} partial pressure resulted in the decrease in anode overvoltage, although open-circuit voltage was dropped. Besides that, the simulation result based on a power-law model for equimolar CH{sub 4}−CO{sub 2} mixture revealed that coking hazard could be suppressed along the fuel flow channel in both open-circuit and closed-circuit conditions.

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

    International Nuclear Information System (INIS)

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

    2017-01-01

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

  1. Influence of anode material on the electrochemical oxidation of 2-naphthol Part 2. Bulk electrolysis experiments

    Energy Technology Data Exchange (ETDEWEB)

    Panizza, M.; Cerisola, G

    2004-08-15

    The electrochemical oxidation of 2-naphthol has been studied by galvanostatic electrolysis, using a range of electrode materials such as lead dioxide, boron-doped diamond (BDD) and Ti-Ru-Sn ternary oxide anodes. The influence of some operating parameters, such as current density, flow-rate and chloride concentration on naphthol oxidation has been investigated in order to find the optimum experimental conditions. Measurements of chemical oxygen demand, HPLC and total organic carbon have been used to follow the oxidation. The experimental data indicate that on PbO{sub 2} and BDD, naphthol oxidation takes place by reaction with electrogenerated hydroxyl radicals and is favoured by low current density and high flow-rate. On the contrary, on a Ti-Ru-Sn ternary oxide the mineralisation of naphthol occurs only in the presence of chloride ions that act as redox mediators and COD removal is affected by chloride concentration and is not significantly influenced by the current density and mass-transfer coefficient. From a comparison of the results of the three electrodes it has been found that boron-doped diamond gives a faster oxidation rate and better current efficiency.

  2. Influence of anode material on the electrochemical oxidation of 2-naphthol. Pt. 2. Bulk electrolysis experiments

    Energy Technology Data Exchange (ETDEWEB)

    Panizza, M.; Cerisola, G. [Genoa Univ. (Italy). Dept. of Chemical and Process Engineering

    2004-08-15

    The electrochemical oxidation of 2-naphthol has been studied by galvanostatic electrolysis, using a range of electrode materials such as lead dioxide, boron-doped diamond (BDD) and Ti-Ru-Sn ternary oxide anodes. The influence of some operating parameters, such as current density, flow-rate and chloride concentration on naphthol oxidation has been investigated in order to find the optimum experimental conditions. Measurements of chemical oxygen demand, HPLC and total organic carbon have been used to follow the oxidation. The experimental data indicate that on PbO{sub 2} and BDD, naphthol oxidation takes place by reaction with electrogenerated hydroxyl radicals and is favoured by low current density and high flow-rate. On the contrary, on a Ti-Ru-Sn ternary oxide the mineralisation of naphthol occurs only in the presence of chloride ions that act as redox mediators and COD removal is affected by chloride concentration and is not significantly influenced by the current density and mass-transfer coefficient. From a comparison of the results of the three electrodes it has been found that boron-doped diamond gives a faster oxidation rate and better current efficiency. (author)

  3. Influence of anode material on the electrochemical oxidation of 2-naphthol Part 2. Bulk electrolysis experiments

    International Nuclear Information System (INIS)

    Panizza, M.; Cerisola, G.

    2004-01-01

    The electrochemical oxidation of 2-naphthol has been studied by galvanostatic electrolysis, using a range of electrode materials such as lead dioxide, boron-doped diamond (BDD) and Ti-Ru-Sn ternary oxide anodes. The influence of some operating parameters, such as current density, flow-rate and chloride concentration on naphthol oxidation has been investigated in order to find the optimum experimental conditions. Measurements of chemical oxygen demand, HPLC and total organic carbon have been used to follow the oxidation. The experimental data indicate that on PbO 2 and BDD, naphthol oxidation takes place by reaction with electrogenerated hydroxyl radicals and is favoured by low current density and high flow-rate. On the contrary, on a Ti-Ru-Sn ternary oxide the mineralisation of naphthol occurs only in the presence of chloride ions that act as redox mediators and COD removal is affected by chloride concentration and is not significantly influenced by the current density and mass-transfer coefficient. From a comparison of the results of the three electrodes it has been found that boron-doped diamond gives a faster oxidation rate and better current efficiency

  4. Development of a tritium monitor combined with an electrochemical tritium pump using a proton conducting oxide

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, M. [National Institute for Fusion Science, Toki, Gifu (Japan); Sugiyama, T. [Nagoya University, Fro-cho, Chikusa-ku, Nagoya (Japan)

    2015-03-15

    The detection of low level tritium is one of the key issues for tritium management in tritium handling facilities. Such a detection can be performed by tritium monitors based on proton conducting oxide technique. We tested a tritium monitoring system composed of a commercial proportional counter combined with an electrochemical hydrogen pump equipped with CaZr{sub 0.9}In{sub 0.1}O{sub 3-α} as proton conducting oxide. The hydrogen pump operated at 973 K under electrolysis conditions using tritiated water vapor (HTO). The proton conducting oxide extracts tritium molecules (HT) from HTO and tritium concentration is measured by the proportional counter. The advantage of the proposed tritium monitoring system is that it is able to convert HTO into molecular hydrogen.

  5. Electrochemical and mass variation behaviour of rhodium oxide electrodes prepared by the polymeric precursor method

    International Nuclear Information System (INIS)

    Santos, M.C.; Oliveira, R.T.S.; Pereira, E.C.; Bulhoes, L.O.S.

    2005-01-01

    This paper describes an investigation of the charging processes of Rh 2 O 3 electrodes in acidic medium using Electrochemical Quartz Crystal Microbalance. The Rh 2 O 3 was prepared by the Pechini method. The microstructural characterization of the rhodium oxide was performed using Scanning Electron Microscopy and the structure was determined by X-ray diffraction. The Rh 2 O 3 oxidizes at potentials higher than 0.8 V. A mass loss of 60 ng was observed during the anodic sweep. The same amount is gained during the cathodic sweep indicating that the process is reversible. From the mass versus charge plots a slope of 8.5 g mol -1 is calculated. Considering a process that involves a two-electron transfer, the oxidation of Rh 2 O 3 to RhO 2 with the loss of a water molecule (18 g mol -1 ) is proposed

  6. MnO2-Graphene Oxide-PEDOT:PSS Nanocomposite for an Electrochemical Supercapacitor

    Science.gov (United States)

    Patil, Dipali S.; Pawar, Sachin A.; Shin, Jae Cheol; Kim, Hyo Jin

    2018-04-01

    A ternary nanocomposite with poly (3,4 ethylene dioxythiophene:poly(styrene sulfonate) (PEDOT:PSS)-MnO2 nanowires-graphene oxide (PMn-GO) was synthesized by using simple chemical route. The formation of the nanocomposite was analyzed by using X-ray diffraction and X-ray photoelectron spectroscopy. Field-emission scanning microscopy (FESEM) revealed the formation of MnO2 nanowires and graphene oxide nanosheets. The highest specific capacitance (areal capacitance) of 841 Fg -1 (177 mFcm -2) at 10 mVs -1 and energy density of 0.593 kWhkg -1 at 0.5 mA were observed for PMn-GO, indicating a constructive synergistic effect of PEDOT:PSS, MnO2 nanowires and graphene oxide. The achieved promising electrochemical characteristics showed that this ternary nanocomposite is a good alternative as an electrode material for supercapacitor.

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

    Science.gov (United States)

    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...

  8. Electrochemical oxidation of COD from real textile wastewaters: Kinetic study and energy consumption.

    Science.gov (United States)

    Zou, Jiaxiu; Peng, Xiaolan; Li, Miao; Xiong, Ying; Wang, Bing; Dong, Faqin; Wang, Bin

    2017-03-01

    In the present study, the electrochemical oxidation of real wastewaters discharged by textile industry was carried out using a boron-doped diamond (BDD) anode. The effect of operational variables, such as applied current density (20-100 mA·cm -2 ), NaCl concentration added to the real wastewaters (0-3 g·L -1 ), and pH value (2.0-10.0), on the kinetics of COD oxidation and on the energy consumption was carefully investigated. The obtained experimental results could be well matched with a proposed kinetic model, in which the indirect oxidation mediated by electrogenerated strong oxidants would be described through a pseudo-first-order kinetic constant k. Values of k exhibited a linear increase with increasing applied current density and decreasing pH value, and an exponential increase with NaCl concentration. Furthermore, high oxidation kinetics resulted in low specific energy consumption, but this conclusion was not suitable to the results obtained under different applied current density. Under the optimum operational conditions, it only took 3 h to complete remove the COD in the real textile wastewaters and the specific energy consumption could be as low as 11.12 kWh·kg -1  COD. The obtained results, low energy consumption and short electrolysis time, allowed to conclude that the electrochemical oxidation based on BDD anodes would have practical industrial application for the treatment of real textile wastewater. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Kinetic investigation of vanadium (V)/(IV) redox couple on electrochemically oxidized graphite electrodes

    International Nuclear Information System (INIS)

    Wang, Wenjun; Wei, Zengfu; Su, Wei; Fan, Xinzhuang; Liu, Jianguo; Yan, Chuanwei; Zeng, Chaoliu

    2016-01-01

    Highlights: • The VO_2"+/VO"2"+ redox reaction of the electrode could be facilitated to some extent with the increasing anodic corrosion. • A real reaction kinetic equation for the oxidation of VO"2"+ on the electrochemically oxidized electrode has been firstly obtained. • The establishment of the kinetic equation is conducive to predict polarization behaviors of the electrodes in engineering application. - Abstract: The morphology, surface composition, wettability and the kinetic parameters of the electrochemically oxidized graphite electrodes obtained under different anodic polarization conditions have been examined by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), contact angle measurements, steady-state polarization and cyclic voltammetry (CV) tests, with an attempt to investigate the inherent correlation between the physicochemical properties and the kinetic characteristics for carbon electrodes used in an all-vanadium redox flow battery (VRFB). When the anodic polarization potential raises up to 1.8 V vs. SCE, the anodic corrosion of the graphite might happen and a large number of oxygen-containing functional groups generate. The VO_2"+/VO"2"+ redox reaction can be facilitated and the reaction reversibility tends to become better with the increasing anodic potential, possibly owing to the increased surface oxides and the resulting improved wettability of the electrode. Based on this, a real reaction kinetic equation for the oxidation of VO"2"+ has been obtained on the electrode polarized at 1.8 V vs. SCE and it can be also well used to predict the polarization behavior of the oxidized electrode in vanadium (IV) acidic solutions.

  10. A new way for preparing superconducting materials: the electrochemical oxidation of La2CuO4

    International Nuclear Information System (INIS)

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

    1990-01-01

    The electrochemical oxidation in alkaline medium is described as a new way for preparing superconducting oxides at room temperature. The application of this method to La 2 CuO 4 gave rise to a metallic material with a superconducting behaviour below 39 K and whose physical and chemical features appear as quite promising [fr

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

    Science.gov (United States)

    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. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Electrochemically Formed Ultrafine Metal Oxide Nanocatalysts for High-Performance Lithium–Oxygen Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Bin; Yan, Pengfei; Xu, Wu; Zheng, Jianming; He, Yang; Luo, Langli; Bowden, Mark E.; Wang, Chong-Min; Zhang, Ji-Guang

    2016-08-10

    Lithium-oxygen (Li-O2) battery has an extremely high theoretical specific energy density as compared with conventional energy storage systems. However, practical application of Li-O2 battery system still faces significant challenges, especially its poor cyclability. In this work, we report a new approach to synthesis ultrafine metal oxide nanocatalysts through an electrochemical pre-lithiation process. This process reduces the size of NiCo2O4 (NCO) particles from 20~30 nm to a uniformly distributed domain of ~ 2 nm and largely improved their catalytic activity. Structurally, the pre-lithiated NCO NWs are featured by ultrafine NiO/CoO nanoparticles, which show high stability during prolonged cycles in terms of morphology and the particle size, therefore maintaining an excellent catalytic effect to oxygen reduction and evolution reactions. Li-O2 battery using this catalyst has demonstrated an initial capacity of 29,280 mAh g-1 and has retained a stable capacity of over 1,000 mAh g-1 after 100 cycles based on the weight of NCO active material. Direct in-situ TEM observation conclusively reveals the lithiation/delithiation process of as-prepared NCO NWs, clarifying the NCO/Li electrochemical reaction mechanism that can be extended to other transition-metal oxides and providing the in depth understandings on the catalysts and battery chemistries of other ternary transition-metal oxides.

  13. Enhanced photocatalytic performance of ZnO nanostructures by electrochemical hybridization with graphene oxide

    Science.gov (United States)

    Pruna, A.; Wu, Z.; Zapien, J. A.; Li, Y. Y.; Ruotolo, A.

    2018-05-01

    Synthesis of zinc oxide (ZnO) nanostructures is reported by electrochemical deposition from an aqueous electrolyte in presence of graphene oxide (GO) with varying oxidation degree. The properties of hybrids were investigated by scanning electron microscopy, X-ray diffraction, Raman, Fourier-Transform Infrared and X-ray photoelectron spectroscopy techniques and photocatalytic measurements. The results indicated the electrodeposition of ZnO in presence of GO with increased oxygen content led to marked differences in the morphology while Raman measurements indicated an increased defect level both in the ZnO and the electrochemically reduced GO (ErGO) within the hybrids. The decrease in C/O atomic ratio of GO (from 0.79 to 0.71) employed for the electrodeposition of ZnO resulted in an increase in photocatalytic efficiency for methylene blue degradation under UV irradiation from 4-folds to 10-folds with respect to non-hybridized ZnO. The observed synergetic effect of cathodic deposition potential and oxygen content in GO towards improving the photocatalytic activity of immobilized ZnO is expected to contribute to further development of more effective deposition approaches for the preparation of high performance hybrid nanostructures.

  14. Electrochemical Corrosion Behavior of Oxidation Layer on Fe30Mn5Al Alloy

    Directory of Open Access Journals (Sweden)

    ZHU Xue-mei

    2017-08-01

    Full Text Available The Fe30Mn5Al alloy was oxidized at 800℃ in air for 160h, the oxidation-induced layer about 15μm thick near the scale-metal interface was induced to transform to ferrite and become enriched in Fe and depletion in Mn. The effect of the oxidation-induced Mn depletion layer on the electrochemical corrosion behavior of Fe30Mn5Al alloy was evaluated. The results show that in 1mol·L-1 Na2SO4 solution, the anodic polarization curve of the Mn depletion layer exhibits self-passivation, compared with Fe30Mn5Al austenitic alloy, and the corrosion potential Evs SCE is increased to -130mV from -750mV and the passive current density ip is decreased to 29μA/cm2 from 310μA/cm2. The electrochemical impedance spectroscopy(EIS of the Mn depletion layer has the larger diameter of capacitive arc, the higher impedance modulus|Z|, and the wider phase degree range, and the fitted polarization resistant Rt is increased to 9.9kΩ·cm2 from 2.7kΩ·cm2 by using an equivalent electric circuit of Rs-(Rt//CPE. The high insulation of the Mn depletion layer leads to an improved corrosion resistance of Fe30Mn5Al austenitic alloy.

  15. Electrochemical catalytic activities of nanoporous palladium rods for methanol electro-oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaoguang; Wang, Weimin; Qi, Zhen; Zhao, Changchun; Ji, Hong; Zhang, Zhonghua [Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials (MOE), School of Materials Science and Engineering, Shandong University, Jingshi Road 73, Jinan 250061 (China)

    2010-10-01

    A novel electrocatalyst, nanoporous palladium (npPd) rods can be facilely fabricated by dealloying a binary Al{sub 80}Pd{sub 20} alloy in a 5 wt.% HCl aqueous solution under free corrosion conditions. The microstructure of these nanoporous palladium rods has been characterized using scanning electron microscopy and transmission electron microscopy. The results show that each Pd rod is several microns in length and several hundred nanometers in diameter. Moreover, all the rods exhibit a typical three-dimensional bicontinuous interpenetrating ligament-channel structure with length scale of 15-20 nm. The electrochemical experiments demonstrate that these peculiar nanoporous palladium rods (mixed with Vulcan XC-72 carbon powders to form a npPd/C catalyst) reveal a superior electrocatalytic performance toward methanol oxidation in the alkaline media. In addition, the electrocatalytic activity obviously depends on the metal loading on the electrode and will reach to the highest level (223.52 mA mg{sup -1}) when applying 0.4 mg cm{sup -2} metal loading on the electrode. Moreover, a competing adsorption mechanism should exist when performing methanol oxidation on the surface of npPd rods, and the electro-oxidation reaction is a diffusion-controlled electrochemical process. Due to the advantages of simplicity and high efficiency in the mass production, the npPd rods can act as a promising candidate for the anode catalyst for direct methanol fuel cells (DMFCs). (author)

  16. High-performance symmetric electrochemical capacitor based on graphene foam and nanostructured manganese oxide

    Directory of Open Access Journals (Sweden)

    Abdulhakeem Bello

    2013-08-01

    Full Text Available We have fabricated a symmetric electrochemical capacitor with high energy and power densities based on a composite of graphene foam (GF with ∼80 wt% of manganese oxide (MnO2 deposited by hydrothermal synthesis. Raman spectroscopy and X-ray diffraction measurements showed the presence of nanocrystalline MnO2 on the GF, while scanning and transmission electron microscopies showed needle-like manganese oxide coated and anchored onto the surface of graphene. Electrochemical measurements of the composite electrode gave a specific capacitance of 240 Fg−1 at a current density of 0.1 Ag−1 for symmetric supercapacitors using a two-electrode configuration. A maximum energy density of 8.3 Whkg−1 was obtained, with power density of 20 kWkg−1 and no capacitance loss after 1000 cycles. GF is an excellent support for pseudo-capacitive oxide materials such as MnO2, and the composite electrode provided a high energy density due to a combination of double-layer and redox capacitance mechanisms.

  17. Activated carbon electrodes: electrochemical oxidation coupled with desalination for wastewater treatment.

    Science.gov (United States)

    Duan, Feng; Li, Yuping; Cao, Hongbin; Wang, Yi; Crittenden, John C; Zhang, Yi

    2015-04-01

    The wastewater usually contains low-concentration organic pollutants and some inorganic salts after biological treatment. In the present work, the possibility of simultaneous removal of them by combining electrochemical oxidation and electrosorption was investigated. Phenol and sodium chloride were chosen as representative of organic pollutants and inorganic salts and a pair of activated carbon plate electrodes were used as anode and cathode. Some important working conditions such as oxygen concentration, applied potential and temperature were evaluated to reach both efficient phenol removal and desalination. Under optimized 2.0 V of applied potential, 38°C of temperature, and 500 mL min(-1) of oxygen flow, over 90% of phenol, 60% of TOC and 20% of salinity were removed during 300 min of electrolysis time. Phenol was removed by both adsorption and electrochemical oxidation, which may proceed directly or indirectly by chlorine and hypochlorite oxidation. Chlorophenols were detected as degradation intermediates, but they were finally transformed to carboxylic acids. Desalination was possibly attributed to electrosorption of ions in the pores of activated carbon electrodes. The charging/regeneration cycling experiment showed good stability of the electrodes. This provides a new strategy for wastewater treatment and recycling. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Study and optimisation of manganese oxide-based electrodes for electrochemical supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Staiti, P.; Lufrano, F. [CNR-ITAE, Istituto di Tecnologie Avanzate per l' Energia ' ' Nicola Giordano' ' , Via Salita S. Lucia n. 5, 98126 S. Lucia, Messina (Italy)

    2009-02-01

    A manganese oxide material was synthesised by an easy precipitation method based on reduction of potassium permanganate(VII) with a manganese(II) salt. The material was treated at different temperatures to study the effect of thermal treatment on capacitive property. The best capacitive performance was obtained with the material treated at 200 C. This material was used to prepare electrodes with different amounts of polymer binder, carbon black and graphite fibres to individuate the optimal composition that gave the best electrochemical performances. It was found that graphite fibres improve the electrochemical performance of electrodes. The highest specific capacitance (267 F g{sup -1} MnO{sub x}) was obtained with an electrode containing 70% of MnO{sub x}, 15% of carbon black, 10% of graphite fibres and 5% of PVDF. This electrode, with CB/GF ratio of 1.5, showed a higher utilization of manganese oxide. The results reported in the present paper further confirmed that manganese oxide is a very interesting material for supercapacitor application. (author)

  19. Recent advances in Phytosterol Oxidation Products.

    Science.gov (United States)

    O'Callaghan, Yvonne; McCarthy, Florence O; O'Brien, Nora M

    2014-04-11

    Phytosterols and their oxidation products have become increasingly investigated in recent years with respect to their roles in diet and nutrition. We present a comprehensive review of recent literature on Phytosterol Oxidation Products (POP) identifying critical areas for future investigation. It is evident that POP are formed on food storage/preparation; are absorbed and found in human serum; do not directly affect cholesterol absorption; have evidence of atherogenicity and inflammation; have distinct levels of cytotoxicity; are implicated with high levels of oxidative stress, glutathione depletion, mitochondrial dysfunction and elevated caspase activity. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Treatment of an azo dye effluent by peroxi-coagulation and its comparison to traditional electrochemical advanced processes.

    Science.gov (United States)

    do Vale-Júnior, Edilson; da Silva, Djalma R; Fajardo, Ana S; Martínez-Huitle, Carlos A

    2018-04-05

    Peroxi-coagulation (PC) is an interesting new process that has not been widely studied in the literature. This work presents the application of this technology to treat an azo dye synthetic effluent, studying the effect of different parameters including initial pH, current density (j), initial dye concentration and supporting electrolyte. The two former variables significantly affected the colour removal of the wastewater, followed by the initial dye concentration and the kind of electrolyte, in a lesser extent. The optimum operating conditions achieved were initial pH of 3.0, j = 33.3 mA cm -2 , 100 mg L -1 of methyl orange (MO) and Na 2 SO 4 as supporting electrolyte. The performance of PC was also compared to other electrochemical advanced processes, under similar experimental conditions. Results indicate that the kinetic decay of the MO increases in the following order: electrocoagulation (EC) oxidation (EO) with electrogenerated H 2 O 2 oxidant character of the homogenous OH radicals generated by EF and PC approaches. The EO process with production of H 2 O 2 (EO-H 2 O 2 ) is limited by mass transport and the EC, as a separation method, takes longer times to achieve similar removal results. Energy requirements about 0.06 kWh g COD -1 , 0.09 kWh g COD -1 , 0.7 kWh g COD -1 and 0.1 kWh g COD -1 were achieved for PC, EF, EO-H 2 O 2 and EC, respectively. Degradation intermediates were monitored and carboxylic acids were detected for PC and EF processes, being rapidly removed by the former technology. PC emerges as a promising and competitive alternative for wastewaters depollution, among other oxidative approaches. Copyright © 2018 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

    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 175μM, with a detection limit of 39nM, and it is free from common interferences such as uric acid and ascorbic acid. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Characterization of electro-oxidation catalysts using scanning electrochemical and mass spectral methods

    Science.gov (United States)

    Jambunathan, Krishnakumar

    Low temperature fuel cells have many potential benefits, including high efficiency, high energy density and environmental friendliness. However, logistically appealing fuels for this system, such as reformed hydrocarbons or alcohols, exhibit poor performance because of catalyst poisoning that occurs during oxidation at the anode. This research focuses on the analysis of several model fuels and catalyst materials to understand the impact of catalyst poisoning on reactivity. Two novel experimental tools were developed based upon the local measurement of catalyst performance using scanning, reactivity mapping probes. The Scanning Electrochemical Microscope (SECM) was used to directly measure the rate constant for hydrogen oxidation in the presence and absence of dissolved CO. The Scanning Differential Electrochemical Mass Spectrometer (SDEMS) was exploited to measure the partial and complete oxidation products of methanol and ethanol oxidation. The reactivity of Pt and Pt/Ru catalysts towards the hydrogen oxidation reaction in the absence and presence of adsorbed CO was elucidated using the SECM. Steady state rate constant measurements in the absence of CO showed that the rate of hydrogen oxidation reaction exceeded 1 cms-1 . Steady state rate constant measurements in the presence of CO indicated that the platinum surface is completely inactive due to adsorbed CO. Addition of as little as 6% Ru to the Pt electrode was found to significantly improve the activity of the electrode towards CO removal. SDEMS was used to study the electro-oxidation of methanol on Pt xRuy electrodes at different electrode potentials and temperatures. Screening measurements performed with the SDEMS showed that PtxRu y electrodes containing 6--40% Ru had the highest activity for methanol oxidation. Current efficiencies for CO2 were also calculated under different conditions. SDEMS was also used to study the electro-oxidation of ethanol on Pt xRuy electrodes. The reaction was found to occur

  3. Electrophoretically deposited graphene oxide and carbon nanotube composite for electrochemical capacitors

    International Nuclear Information System (INIS)

    Ajayi, Obafunso A; Wong, Chee Wei; Guitierrez, Daniel H; Peaslee, David; Cheng, Arthur; Chen, Bin; Gao, Theodore

    2015-01-01

    We report a scalable one-step electrode fabrication approach for synthesizing composite carbon-based supercapacitors with synergistic outcomes. Multi-walled carbon nanotubes (MWCNTs) were successfully integrated into our modified electrophoretic deposition process to directly form composite MWCNT–GO electrochemical capacitor electrodes (where GO is graphene oxide) with superior performance to solely GO electrodes. The measured capacitance improved threefold, reaching a maximum specific capacitance of 231 F g"−"1. Upon thermal reduction, MWCNT–GO electrode sheet resistance decreased by a factor of 8, significantly greater than the 2× decrease of those without MWCNTs. (paper)

  4. Electrochemical capacitance of nanocomposite films formed by loading carbon nanotubes with ruthenium oxide

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jae-Kyung [Department of Chemical Engineering, University of Seoul, 90 Chonnong-dong, Tongdaemun-gu, Seoul (Korea, Republic of); Pathan, Habib M.; Jung, Kwang-Deog; Joo, Oh-Shim [Eco-Nano Research Center, Korea Institute of Science and Technology (KIST), P.O. Box 131, Cheongryang, Seoul (Korea, Republic of)

    2006-09-22

    This work reports the supercapacitive properties of composite films of multiwalled carbon nanotubes (MWNT) and ruthenium oxide (RuO{sub 2}). Transmission and scanning electron microscopy, cyclic voltammetry, and electrochemical studies revealed that the nanoporous three-dimensional arrangement of RuO{sub 2}-coated MWNT in these films facilitated the improvement of electron and ion transfer relative to MWNT films. The capacitance was measured for films of different RuO{sub 2} loading, revealing specific capacitances per mass as high as 628Fg{sup -1}. The energy storage density of the electrode has increased about three times as compared to MWNT treated with piranha solution. (author)

  5. Oxidation of Natural Bioactive Flavonolignan 2,3-Dehydrosilybin: An Electrochemical and Spectral Study

    Czech Academy of Sciences Publication Activity Database

    Sokolová, Romana; Kocábová, Jana; Marhol, Petr; Fiedler, Jan; Biedermann, David; Vacek, J.; Křen, Vladimír

    2017-01-01

    Roč. 121, č. 28 (2017), s. 6841-6846 ISSN 1520-6106 R&D Projects: GA ČR(CZ) GA15-03037S Grant - others:Rada Programu interní podpory projektů mezinárodní spolupráce AV ČR M200401201 Program:M Institutional support: RVO:61388955 ; RVO:61388971 Keywords : Electrochemical oxidation * Chemical bonds * Electrochemistry Subject RIV: CG - Electrochemistry OBOR OECD: Physical chemistry Impact factor: 3.177, year: 2016

  6. Advanced oxidation technologies : photocatalytic treatment of wastewater

    OpenAIRE

    Chen, J.

    1997-01-01

    7.1. Summary and conclusions

    The last two decennia have shown a growing interest in the photocatalytic treatment of wastewater, and more and more research has been carried out into the various aspects of photocatalysis, varying from highly fundamental aspects to practical application. However, despite all this research, there is still much to investigate. Suggested photocatalytic mechanisms, such as those for oxidation by hydroxyl radicals and for oxidation at the surface of photocata...

  7. Recent Advances in Layered Ti3 C2 Tx MXene for Electrochemical Energy Storage.

    Science.gov (United States)

    Xiong, Dongbin; Li, Xifei; Bai, Zhimin; Lu, Shigang

    2018-04-01

    Ti 3 C 2 T x , a typical representative among the emerging family of 2D layered transition metal carbides and/or nitrides referred to as MXenes, has exhibited multiple advantages including metallic conductivity, a plastic layer structure, small band gaps, and the hydrophilic nature of its functionalized surface. As a result, this 2D material is intensively investigated for application in the energy storage field. The composition, morphology and texture, surface chemistry, and structural configuration of Ti 3 C 2 T x directly influence its electrochemical performance, e.g., the use of a well-designed 2D Ti 3 C 2 T x as a rechargeable battery anode has significantly enhanced battery performance by providing more chemically active interfaces, shortened ion-diffusion lengths, and improved in-plane carrier/charge-transport kinetics. Some recent progresses of Ti 3 C 2 T x MXene are achieved in energy storage. This Review summarizes recent advances in the synthesis and electrochemical energy storage applications of Ti 3 C 2 T x MXene including supercapacitors, lithium-ion batteries, sodium-ion batteries, and lithium-sulfur batteries. The current opportunities and future challenges of Ti 3 C 2 T x MXene are addressed for energy-storage devices. This Review seeks to provide a rational and in-depth understanding of the relation between the electrochemical performance and the nanostructural/chemical composition of Ti 3 C 2 T x , which will promote the further development of 2D MXenes in energy-storage applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Advanced Electrochemical Machining (ECM) for tungsten surface micro-structuring in blanket applications

    Energy Technology Data Exchange (ETDEWEB)

    Holstein, Nils, E-mail: nils.holstein@kit.edu [Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Baden-Württemberg (Germany); Krauss, Wolfgang; Konys, Jürgen [Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Baden-Württemberg (Germany); Heuer, Simon; Weber, Thomas [Research Center Jülich, Institute of Energy- and Climate Research – Plasma Physics (IEK-4), D-52425 Jülich (Germany)

    2016-11-01

    Highlights: • Electrochemical Machining is an appropriate tool for tungsten shaping. • Progress in shaping achieved by combination of ECM with advanced micro-lithography. • Application in First Wall for connection of plasma facing material to breeder blanket. • Successful development of adhesion promotors by ECM for plasma spraying interlayers. • Microstructure electrochemical manufacturing of tungsten in sizes of 100 μm achieved. - Abstract: Plasma facing components for fusion applications must have to exhibit long-term stability under extreme physical conditions, and therefore any material imperfections caused by mechanical and/or thermal stresses in the shaping processes cannot be tolerated due to a high risk of possible technical failures under fusion conditions. To avoid such defects, the method of Electrochemical Machining (ECM) enables a complete defect-free processing of removal of tungsten material during the desired shaping, also for high penetration depths. Furthermore, supported by lithographic mask pretreatment, three-dimensional distinct geometric structures can be positive-imaged via the directional galvanic dissolution applying M-ECM process into the tungsten bulk material. New required applications for tungsten components, e.g. as adhesion promotors in W-surfaces to enable sure grip and bonding of thick plasma-spraying layers for blanket components, will define the way of further miniaturization of well-established millimeter dimensioned M-ECM shaping processes to dimensions of 100 μm and furthermore down to 50 μm. Besides current M-ECM limits the article describes inevitable needs of further developments for mask resists, mask materials and the resulting ECM parameters, to reach the needed accuracy in tungsten microstructure. The achieved progress and observed correlations of processing parameters will be manifested by produced demonstrators made by the new “μM”-ECM process.

  9. Advanced Electrochemical Machining (ECM) for tungsten surface micro-structuring in blanket applications

    International Nuclear Information System (INIS)

    Holstein, Nils; Krauss, Wolfgang; Konys, Jürgen; Heuer, Simon; Weber, Thomas

    2016-01-01

    Highlights: • Electrochemical Machining is an appropriate tool for tungsten shaping. • Progress in shaping achieved by combination of ECM with advanced micro-lithography. • Application in First Wall for connection of plasma facing material to breeder blanket. • Successful development of adhesion promotors by ECM for plasma spraying interlayers. • Microstructure electrochemical manufacturing of tungsten in sizes of 100 μm achieved. - Abstract: Plasma facing components for fusion applications must have to exhibit long-term stability under extreme physical conditions, and therefore any material imperfections caused by mechanical and/or thermal stresses in the shaping processes cannot be tolerated due to a high risk of possible technical failures under fusion conditions. To avoid such defects, the method of Electrochemical Machining (ECM) enables a complete defect-free processing of removal of tungsten material during the desired shaping, also for high penetration depths. Furthermore, supported by lithographic mask pretreatment, three-dimensional distinct geometric structures can be positive-imaged via the directional galvanic dissolution applying M-ECM process into the tungsten bulk material. New required applications for tungsten components, e.g. as adhesion promotors in W-surfaces to enable sure grip and bonding of thick plasma-spraying layers for blanket components, will define the way of further miniaturization of well-established millimeter dimensioned M-ECM shaping processes to dimensions of 100 μm and furthermore down to 50 μm. Besides current M-ECM limits the article describes inevitable needs of further developments for mask resists, mask materials and the resulting ECM parameters, to reach the needed accuracy in tungsten microstructure. The achieved progress and observed correlations of processing parameters will be manifested by produced demonstrators made by the new “μM”-ECM process.

  10. Simulating Linear Sweep Voltammetry from First-Principles: Application to Electrochemical Oxidation of Water on Pt(111) and Pt3Ni(111)

    DEFF Research Database (Denmark)

    Viswanathan, Venkatasubramanian; Hansen, Heine Anton; Rossmeisl, Jan

    2012-01-01

    Cyclic voltammetry is a fundamental experimental method for characterizing adsorbates on electrochemical surfaces. We present a model for the electrochemical solid–liquid interface, and we simulate the linear sweep voltammogram of the electrochemical oxidation of H2O on Pt(111) and Pt3Ni(111...

  11. Structural, optical and electrochemical properties of F-doped vanadium oxide transparent semiconducting thin films

    Energy Technology Data Exchange (ETDEWEB)

    Mousavi, M.; Khorrami, G.H. [University of Bojnord, Department of Physics, Faculty of Basic Science, Bojnord (Iran, Islamic Republic of); Kompany, A. [Ferdowsi University of Mashhad, Department of Physics, Mashhad (Iran, Islamic Republic of); Yazdi, S.T. [Payame Noor University (PNU), Department of Physics, Tehran (Iran, Islamic Republic of)

    2017-12-15

    In this study, F-doped vanadium oxide thin films with doping levels up to 60 at % were prepared by spray pyrolysis method on glass substrates. To measure the electrochemical properties, some films were deposited on fluorine-tin oxide coated glass substrates. The effect of F-doping on the structural, electrical, optical and electrochemical properties of vanadium oxide samples was investigated. The X-ray diffractographs analysis has shown that all the samples grow in tetragonal β-V{sub 2}O{sub 5} phase structure with the preferred orientation of [200]. The intensity of (200) peak belonging to β-V{sub 2}O{sub 5} phase was strongest in the undoped vanadium oxide film. The scanning electron microscopy images show that the samples have nanorod- and nanobelt-shaped structure. The size of the nanobelts in the F-doped vanadium oxide films is smaller than that in the pure sample and the width of the nanobelts increases from 30 to 70 nm with F concentration. With increasing F-doping level from 10 to 60 at %, the resistivity, the transparency and the optical band gap decrease from 111 to 20 Ω cm, 70 to 50% and 2.4 to 2.36 eV, respectively. The cyclic voltammogram (CV) results show that the undoped sample has the most extensive CV and by increasing F-doping level from 20 to 60 at %, the area of the CV is expanded. The anodic and cathodic peaks in F-doped samples are stronger. (orig.)

  12. Oxidation of organics in water in microfluidic electrochemical reactors: Theoretical model and experiments

    International Nuclear Information System (INIS)

    Scialdone, Onofrio; Guarisco, Chiara; Galia, Alessandro

    2011-01-01

    The electrochemical oxidation of organics in water performed in micro reactors on boron doped diamond (BDD) anode was investigated both theoretically and experimentally in order to find the influence of various operative parameters on the conversion and the current efficiency CE of the process. The electrochemical oxidation of formic acid (FA) was selected as a model case. High conversions for a single passage of the electrolytic solution inside the cell were obtained by operating with proper residence times and low distances between cathode and anode. The effect of initial concentration, flow rate and current density was investigated in detail. Theoretical predictions were in very good agreement with experimental results for both mass transfer control, oxidation reaction control and mixed kinetic regimes in spite of the fact that no adjustable parameters was used. Mass transfer process was successfully modelled by considering for simplicity a constant Sh number (e.g., a constant mass transfer coefficient k m ) for a process performed with no high values of the current intensity to minimize the effect of the gas bubbling on the flowdynamic pattern. For mixed kinetic regimes, two different modelling approaches were used. In the first one, the oxidation of organics at BDD was assumed to be mass transfer controlled and to occur with an intrinsic 100% CE when applied current density is higher than the limiting current density. In the second case, the CE of the process was modelled assuming that the competition between organic and water oxidation depends only on the electrodic material and on the nature and the concentration of the organic. In the latter case a better agreement between experimental data and theoretical predictions was observed.

  13. Simple and label-free electrochemical impedance Amelogenin gene hybridization biosensing based on reduced graphene oxide.

    Science.gov (United States)

    Benvidi, Ali; Rajabzadeh, Nooshin; Mazloum-Ardakani, Mohammad; Heidari, Mohammad Mehdi; Mulchandani, Ashok

    2014-08-15

    The increasing desire for sensitive, easy, low-cost, and label free methods for the detection of DNA sequences has become a vital matter in biomedical research. For the first time a novel label-free biosensor for sensitive detection of Amelogenin gene (AMEL) using reduced graphene oxide modified glassy carbon electrode (GCE/RGO) has been developed. In this work, detection of DNA hybridization of the target and probe DNA was investigated by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The optimum conditions were found for the immobilization of probe on RGO surface and its hybridization with the target DNA. CV and EIS carried out in an aqueous solution containing [Fe(CN)6](3-/4-) redox pair have been used for the biosensor characterization. The biosensor has a wide linear range from 1.0×10(-20) to 1.0×10(-14)M with the lower detection limit of 3.2×10(-21)M. Moreover, the present electrochemical detection offers some unique advantages such as ultrahigh sensitivity, simplicity, and feasibility for apparatus miniaturization in analytical tests. The excellent performance of the biosensor is attributed to large surface-to-volume ratio and high conductivity of RGO, which enhances the probe absorption and promotes direct electron transfer between probe and the electrode surface. This electrochemical DNA sensor could be used for the detection of specific ssDNA sequence in real biological samples. Copyright © 2014 Elsevier B.V. All rights reserved.

  14. Nonenzymatic electrochemical sensor based on imidazole-functionalized graphene oxide for progesterone detection.

    Science.gov (United States)

    Gevaerd, Ava; Blaskievicz, Sirlon F; Zarbin, Aldo J G; Orth, Elisa S; Bergamini, Márcio F; Marcolino-Junior, Luiz H

    2018-07-30

    The modification of electrode surfaces has been the target of study for many researchers in order to improve the analytical performance of electrochemical sensors. Herein, the use of an imidazole-functionalized graphene oxide (GO-IMZ) as an artificial enzymatic active site for voltammetric determination of progesterone (P4) is described for the first time. The morphology and electrochemical performance of electrode modified with GO-IMZ were characterized by scanning electron microscopy and cyclic voltammetry, respectively. Under optimized conditions, the proposed sensor showed a synergistic effect of the GO sheets and the imidazole groups anchored on its backbone, which promoted a significant enhancement on electrochemical reduction of P4. Figures of merits such as linear dynamic response for P4 concentration ranging from 0.22 to 14.0 μmol L -1 , limit of detection of 68 nmol L -1 and limit of quantification and 210 nmol L -1 were found. In addition, presented a higher sensitivity, 426 nA L µmol -1 , when compared to the unmodified electrode. Overall, the proposed device showed to be a promising platform for a simple, rapid, and direct analysis of progesterone. Copyright © 2018 Elsevier B.V. All rights reserved.

  15. Electrochemical Oxidation of EDTA in Nuclear Wastewater Using Platinum Supported on Activated Carbon Fibers

    Science.gov (United States)

    Zhao, Bo; Zhu, Wenkun; Mu, Tao; Hu, Zuowen; Duan, Tao

    2017-01-01

    A novel Pt/ACF (Pt supported on activated carbon fibers) electrode was successfully prepared with impregnation and electrodeposition method. Characterization of the electrodes indicated that the Pt/ACF electrode had a larger effective area and more active sites. Electrochemical degradation of ethylenediaminetetra-acetic acid (EDTA) in aqueous solution with Pt/ACF electrodes was investigated. The results showed that the 3% Pt/ACF electrode had a better effect on EDTA removal. The operational parameters influencing the electrochemical degradation of EDTA with 3% Pt/ACF electrode were optimized and the optimal removal of EDTA and chemical oxygen demand (COD) were 94% and 60% after 100 min on condition of the electrolyte concentration, initial concentration of EDTA, current density and initial value of pH were 0.1 mol/L, 300 mg/L, 40 mA/cm2 and 5.0, respectively. The degradation intermediates of EDTA in electrochemical oxidation with 3% Pt/ACF electrode were identified by gas chromatography-mass spectrum (GC-MS). PMID:28754016

  16. A study of the characteristics of indium tin oxide after chlorine electro-chemical treatment

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Moonsoo; Kim, Jongmin; Cho, Jaehee; Kim, Hyunwoo; Lee, Nayoung; Choi, Byoungdeog, E-mail: bdchoi@skku.edu

    2016-10-15

    Graphical abstract: The presence of Chlorine in the outer surface resulted in a highly electro-negative surface states and an increase in the vacuum energy level. - Highlights: • We investigated the influence of chlorine surface treatment on ITO properties. • Chlorination induced the change of the electro-static potential in the outer surface. • Chlorine electro-chemical treatment of ITO is a simple, fast and effective technique. - Abstract: In this work, we investigate the influence of a chlorine-based electro-chemical surface treatment on the characteristics of indium tin oxide (ITO) including the work function, chemical composition, and phase transition. The treated ITOs were characterized using X-ray photoelectron spectroscopy (XPS), ultra-violet photoelectron spectroscopy (UPS), 4-point probe measurements, and grazing incidence X-ray diffraction (GI-XRD). We confirmed a change of the chemical composition in the near-surface region of the ITO and the formation of indium-chlorine (In-Cl) bonds and surface dipoles (via XPS). In particular, the change of the electro-static potential in the outer surface was caused by chlorination. Due to the vacuum-level shift after the electro-chemical treatment in a dilute hydrochloric acid, the ITO work function was increased by ∼0.43 eV (via UPS); furthermore, the electro-negativity of the chlorine anions attracted electrons to emit them from the hole transport layer (HTL) to the ITO anodes, resulting in an increase of the hole-injection efficiency.

  17. Decolourisation of simulated reactive dyebath effluents by electrochemical oxidation assisted by UV light.

    Science.gov (United States)

    López-Grimau, V; Gutiérrez, M C

    2006-01-01

    This study is focused on the optimisation of the electrochemical decolourisation of textile effluents containing reactive dyes with the aim of making feasible-technically and economically-this method at industrial scale. Coloured waters were treated in continuous at low current density, to reduce the electrical consumption. Ti/PtO(x) electrodes were used to oxidize simulated dyebaths prepared with an azo/dichlorotriazine reactive dye (C.I. Reactive Orange 4). The decolourisation yield was dependent on the dyeing electrolyte (NaCl or Na(2)SO(4)). Dyeing effluents which contained from 0.5 to 20 gl(-1) of NaCl reached a high decolourisation yield, depending on the current density, immediately after the electrochemical process. These results were improved when the effluents were stored for several hours under solar light. After the electrochemical treatment the effluents were stored in a tank and exposed under different lighting conditions: UV light, solar light and darkness. The evolution of the decolourisation versus the time of storage was reported and kinetic constants were calculated. The time of storage was significantly reduced by the application of UV light. A dye mineralization study was also carried out on a concentrated dyebath. A TOC removal of 81% was obtained when high current density was applied for a prolonged treatment with recirculation. This treatment required a high electrical consumption.

  18. Electrochemical Oxidation of EDTA in Nuclear Wastewater Using Platinum Supported on Activated Carbon Fibers.

    Science.gov (United States)

    Zhao, Bo; Zhu, Wenkun; Mu, Tao; Hu, Zuowen; Duan, Tao

    2017-07-21

    A novel Pt/ACF (Pt supported on activated carbon fibers) electrode was successfully prepared with impregnation and electrodeposition method. Characterization of the electrodes indicated that the Pt/ACF electrode had a larger effective area and more active sites. Electrochemical degradation of ethylenediaminetetra-acetic acid (EDTA) in aqueous solution with Pt/ACF electrodes was investigated. The results showed that the 3% Pt/ACF electrode had a better effect on EDTA removal. The operational parameters influencing the electrochemical degradation of EDTA with 3% Pt/ACF electrode were optimized and the optimal removal of EDTA and chemical oxygen demand (COD) were 94% and 60% after 100 min on condition of the electrolyte concentration, initial concentration of EDTA, current density and initial value of pH were 0.1 mol/L, 300 mg/L, 40 mA/cm² and 5.0, respectively. The degradation intermediates of EDTA in electrochemical oxidation with 3% Pt/ACF electrode were identified by gas chromatography-mass spectrum (GC-MS).

  19. Structure dependent electrochemical performance of Li-rich layered oxides in lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Fang; Yao, Yuze; Wang, Haiyan; Xu, Gui-Liang; Amine, Khalil; Sun, Shi-Gang; Shao, Minhua

    2017-04-08

    Rational and precise control of the structure and dimension of electrode materials is an efficient way to improve their electrochemical performance. In this work, solvothermal or co-precipitation method is used to synthesize lithium-rich layered oxide materials of Li1.2Mn0.56Co0.12Ni0.12O2 (LLO) with various morphologies and structures, including microspheres, microrods, nanoplates, and irregular nanoparticles. These materials exhibit strong structure- dependent electrochemical properties. The porous hierarchical structured LLO microrods exhibit the best performance, delivering a discharge capacity of 264.6 mAh g(-1) at 0.5 C with over 91% retention after 100 cycles. At a high rate of 5 C, a high discharge capacity of 173.6 mAh g(-1) can be achieved. This work reveals the relationship between the morphologies and electrochemical properties of LLO cathode materials, and provides a feasible approach to fabricating robust and high-performance electrode materials for lithium-ion batteries.

  20. Advanced Oxidation: Oxalate Decomposition Testing With Ozone

    International Nuclear Information System (INIS)

    Ketusky, E.; Subramanian, K.

    2012-01-01

    At the Savannah River Site (SRS), oxalic acid is currently considered the preferred agent for chemically cleaning the large underground Liquid Radioactive Waste Tanks. It is applied only in the final stages of emptying a tank when generally less than 5,000 kg of waste solids remain, and slurrying based removal methods are no-longer effective. The use of oxalic acid is preferred because of its combined dissolution and chelating properties, as well as the fact that corrosion to the carbon steel tank walls can be controlled. Although oxalic acid is the preferred agent, there are significant potential downstream impacts. Impacts include: (1) Degraded evaporator operation; (2) Resultant oxalate precipitates taking away critically needed operating volume; and (3) Eventual creation of significant volumes of additional feed to salt processing. As an alternative to dealing with the downstream impacts, oxalate decomposition using variations of ozone based Advanced Oxidation Process (AOP) were investigated. In general AOPs use ozone or peroxide and a catalyst to create hydroxyl radicals. Hydroxyl radicals have among the highest oxidation potentials, and are commonly used to decompose organics. Although oxalate is considered among the most difficult organic to decompose, the ability of hydroxyl radicals to decompose oxalate is considered to be well demonstrated. In addition, as AOPs are considered to be 'green' their use enables any net chemical additions to the waste to be minimized. In order to test the ability to decompose the oxalate and determine the decomposition rates, a test rig was designed, where 10 vol% ozone would be educted into a spent oxalic acid decomposition loop, with the loop maintained at 70 C and recirculated at 40L/min. Each of the spent oxalic acid streams would be created from three oxalic acid strikes of an F-area simulant (i.e., Purex = high Fe/Al concentration) and H-area simulant (i.e., H area modified Purex = high Al/Fe concentration) after nearing

  1. ADVANCED OXIDATION: OXALATE DECOMPOSITION TESTING WITH OZONE

    Energy Technology Data Exchange (ETDEWEB)

    Ketusky, E.; Subramanian, K.

    2012-02-29

    At the Savannah River Site (SRS), oxalic acid is currently considered the preferred agent for chemically cleaning the large underground Liquid Radioactive Waste Tanks. It is applied only in the final stages of emptying a tank when generally less than 5,000 kg of waste solids remain, and slurrying based removal methods are no-longer effective. The use of oxalic acid is preferred because of its combined dissolution and chelating properties, as well as the fact that corrosion to the carbon steel tank walls can be controlled. Although oxalic acid is the preferred agent, there are significant potential downstream impacts. Impacts include: (1) Degraded evaporator operation; (2) Resultant oxalate precipitates taking away critically needed operating volume; and (3) Eventual creation of significant volumes of additional feed to salt processing. As an alternative to dealing with the downstream impacts, oxalate decomposition using variations of ozone based Advanced Oxidation Process (AOP) were investigated. In general AOPs use ozone or peroxide and a catalyst to create hydroxyl radicals. Hydroxyl radicals have among the highest oxidation potentials, and are commonly used to decompose organics. Although oxalate is considered among the most difficult organic to decompose, the ability of hydroxyl radicals to decompose oxalate is considered to be well demonstrated. In addition, as AOPs are considered to be 'green' their use enables any net chemical additions to the waste to be minimized. In order to test the ability to decompose the oxalate and determine the decomposition rates, a test rig was designed, where 10 vol% ozone would be educted into a spent oxalic acid decomposition loop, with the loop maintained at 70 C and recirculated at 40L/min. Each of the spent oxalic acid streams would be created from three oxalic acid strikes of an F-area simulant (i.e., Purex = high Fe/Al concentration) and H-area simulant (i.e., H area modified Purex = high Al/Fe concentration

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

    Science.gov (United States)

    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 μM with a low detection limit of 0.01 μM (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. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Electrochemical disinfection of bacteria-laden water using antimony-doped tin-tungsten-oxide electrodes.

    Science.gov (United States)

    Ghasemian, Saloumeh; Asadishad, Bahareh; Omanovic, Sasha; Tufenkji, Nathalie

    2017-12-01

    Electrochemical disinfection has been shown to be an efficient method with a shortrequired contact time for treatment of drinking water supplies, industrial raw water supplies, liquid foodstuffs, and wastewater effluents. In the present work, the electrochemical disinfection of saline water contaminated with bacteria was investigated in chloride-containing solutions using Sb-doped Sn 80% -W 20% -oxide anodes. The influence of current density, bacterial load, initial chloride concentration, solution pH, and the type of bacteria (E. coli D21, E. coli O157:H7, and E. faecalis) on disinfection efficacy was systematically examined. The impact of natural organic matter and a radical scavenger on the disinfection process was also examined. The electrochemical system was highly effective in bacterial inactivation for a 0.1 M NaCl solution contaminated with ∼10 7  CFU/mL bacteria by applying a current density ≥1 mA/cm 2 through the cell.100% inactivation of E. coli D21 was achieved with a contact time of less than 60 s and power consumption of 48 Wh/m 3 , by applying a current density of 6 mA/cm 2 in a 0.1 M NaCl solution contaminated with ∼10 7 CFU/mL. Reactive chlorine species as well as reactive oxygen species (e.g. hydroxyl radicals) generated in situ during the electrochemical process were determined to be responsible for inactivation of bacteria. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Experience with oxide fuel for advanced reactors

    International Nuclear Information System (INIS)

    Leggett, R.D.

    1984-01-01

    This paper focuses on the use and potential of oxide fuel systems for the LMFBR. The flawless performance of mixed oxide (UO 2 -PuO 2 ) fuel in FFTF to 100,000 MWd/MTM is reviewed and means for achieving 200,000 MWd/MTM are presented. This includes using non-swelling alloys for cladding and ducts to overcome the limitations caused by swelling of the current alloys. Examples are provided of the inherently safe characteristics of oxide fuel including a large negative Doppler coefficient, its dispersive nature under hypothetical accident scenarios, and the low energy molten fuel-coolant interaction. Developments in fuel fabrication and reprocessing that stress safety and reduced personnel exposure are presented. Lastly, the flexibility to design for maximum fuel supply (high breeding gain) or minimum fuel cost (long lifetime) is shown

  5. Experience with oxide fuel for advanced reactors

    International Nuclear Information System (INIS)

    Leggett, R.D.

    1984-04-01

    This paper focuses on the use and potential of oxide fuel system for the LMFBR. The flawless performance of mixed oxide (UO 2 -PuO 2 ) fuel in FFTF to 100,000 MWd/MTM is reviewed and means for achieving 200,000 MWd/MTM are presented. This includes using non-swelling alloys for cladding and ducts to overcome the limitations caused by swelling of the current alloys. Exampled are provided of the inherently safe characteristics of oxide fuel including a large negative Doppler coefficient, its dispersive nature under hypothetical accident scenarios, and the low energy molten fuel-coolant interaction. Developments in fuel fabrication and reprocessing that stress safety and reduced personnel exposure are presented. Lastly, the flexibility to design for maximum fuel supply (high breeding gain) or minimum fuel cost (long lifetime) is shown

  6. Recent Advances in Electrochemical Biosensors Based on Fullerene-C60 Nano-Structured Platforms.

    Science.gov (United States)

    Pilehvar, Sanaz; De Wael, Karolien

    2015-11-23

    Nanotechnology is becoming increasingly important in the field of (bio)sensors. The performance and sensitivity of biosensors is greatly improved with the integration of nanomaterials into their construction. Since its first discovery, fullerene-C60 has been the object of extensive research. Its unique and favorable characteristics of easy chemical modification, conductivity, and electrochemical properties has led to its tremendous use in (bio)sensor applications. This paper provides a concise review of advances in fullerene-C60 research and its use as a nanomaterial for the development of biosensors. We examine the research work reported in the literature on the synthesis, functionalization, approaches to nanostructuring electrodes with fullerene, and outline some of the exciting applications in the field of (bio)sensing.

  7. Application of oxide fine-mesh electrodes composed of Sb-SnO2 for the electrochemical oxidation of Cibacron Marine FG using an SPE filter-press reactor

    International Nuclear Information System (INIS)

    Da Silva, Leonardo M.; Gonçalves, Ismael C.; Teles, José J.S.; Franco, Débora V.

    2014-01-01

    Highlights: • Oxide fine-mesh electrodes composed of Sb-SnO 2 (OFM-Sb-SnO 2 ) were fabricated and applied to the decolourisation and mineralisation of dye solutions using an SPE filter-press reactor. • An electrode mechanism was proposed for the irreversible parallel reactions comprising the oxygen evolution reaction (OER) and the electrochemical advanced oxidation process (EAOP) during the electrolysis of electrolyte-free dye solutions. • The reduction in current efficiency for the OER during the oxidation of Cibacron Marine FG (CMFG) increased the electrode stability. - Abstract: Oxide fine-mesh electrodes composed of tin dioxide doped with antimony (OFM-Sb-SnO 2 ), which had different percentages of Sb, were prepared using the thermal decomposition method on a stainless steel fine-mesh support for application in a solid polymer electrolyte (SPE) filter-press reactor. The electrochemical oxidation of Cibacron ® Marine FG (CMFG) was carried out during recirculation through a plug-flow reactor, using electrolyte-free dye solutions. An influence of the Sb content on the electrochemical oxidation of CMFG was verified. The highest combustion rate of CMFG was obtained using an electrode containing 6.57 mol% Sb. Studies were carried out as a function of the initial dye concentration (IDC) and the applied current density (j) for this particular electrode composition. It was verified that the decolourisation and mineralisation reactions were affected considerably by IDC and j. In trying to interpret the experimental findings, an electrode mechanism was proposed for the irreversible parallel reactions comprising the oxygen evolution reaction (OER) and the advanced oxidation process (EAOP). The instantaneous current efficiency (ICE) for the mineralisation reaction was calculated for the different cases using the average mass-transport coefficient () and the initial limiting current (j L 0 ) values. The energy consumption (EC) was also calculated for the

  8. Effect of Different Binders on the Electrochemical Performance of Metal Oxide Anode for Lithium-Ion Batteries

    Science.gov (United States)

    Wang, Rui; Feng, Lili; Yang, Wenrong; Zhang, Yinyin; Zhang, Yanli; Bai, Wei; Liu, Bo; Zhang, Wei; Chuan, Yongming; Zheng, Ziguang; Guan, Hongjin

    2017-10-01

    When testing the electrochemical performance of metal oxide anode for lithium-ion batteries (LIBs), binder played important role on the electrochemical performance. Which binder was more suitable for preparing transition metal oxides anodes of LIBs has not been systematically researched. Herein, five different binders such as polyvinylidene fluoride (PVDF) HSV900, PVDF 301F, PVDF Solvay5130, the mixture of styrene butadiene rubber and sodium carboxymethyl cellulose (SBR+CMC), and polyacrylonitrile (LA133) were studied to make anode electrodes (compared to the full battery). The electrochemical tests show that using SBR+CMC and LA133 binder which use water as solution were significantly better than PVDF. The SBR+CMC binder remarkably improve the bonding capacity, cycle stability, and rate performance of battery anode, and the capacity retention was about 87% after 50th cycle relative to the second cycle. SBR+CMC binder was more suitable for making transition metal oxides anodes of LIBs.

  9. Electrochemical oxidation of cholesterol in acetonitrile leads to the formation of cholesta-4,6-dien-3-one

    International Nuclear Information System (INIS)

    Hosokawa, Yu-Ya; Hakamata, Hideki; Murakami, Tomonori; Aoyagi, Sakae; Kuroda, Minpei; Mimaki, Yoshihiro; Ito, Ayumi; Morosawa, Sayaka; Kusu, Fumiyo

    2009-01-01

    Cholesterol was shown to be oxidized at the glassy carbon electrode in an acetonitrile-2-propanol mixture and this oxidation reaction was applied to the determination of serum total cholesterol by high-performance liquid chromatography with electrochemical detection (K. Hojo, H. Hakamata, A. Ito, A. Kotani, C. Furukawa, Y.Y. Hosokawa, F. Kusu, J. Chromatogr. A 1166 (2007) 135-141). To gain insight into the detection mechanisms of cholesterol, an electrolytic product of cholesterol was collected and characterized by infrared spectroscopy, one- and two-dimensional nuclear magnetic resonance, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The three techniques, together with comparisons of literature spectral data, confirmed the formation of cholesta-4,6-dien-3-one. The conversion of cholesterol to cholesta-4,6-dien-3-one, a four-electron, four-proton electrochemical process, has been proposed as an electrochemical oxidation mechanism of cholesterol in acetonitrile.

  10. Electrochemical intercalation of lithium into polypyrrole/silver vanadium oxide composite used for lithium primary batteries

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong-Won; Popov, Branko N. [Center for Electrochemical Engineering, Department of Chemical Engineering, University of South Carolina, Columbia, SC 29208 (United States)

    2006-10-20

    Hybrid composites of polypyrrole (PPy) and silver vanadium oxide (SVO) used for lithium primary batteries were chemically synthesized by an oxidative polymerization of pyrrole monomer on the SVO surface in an acidic medium. The composite electrode exhibited higher discharge capacity and better rate capability as compared with the pristine SVO electrode. The improvement in electrochemical performance of the composite electrode was due to PPy which accommodates lithium ions and also enhances the SVO utilization. Chronoamperometric and ac-impedance measurements indicated that lithium intercalation proceeds under the mixed control by interfacial charge transfer and diffusion. The enhanced SVO utilization in the composite electrode results from a facilitated kinetics of interfacial charge transfer in the presence of PPy. (author)

  11. Electrochemical intercalation of lithium into polypyrrole/silver vanadium oxide composite used for lithium primary batteries

    Science.gov (United States)

    Lee, Jong-Won; Popov, Branko N.

    Hybrid composites of polypyrrole (PPy) and silver vanadium oxide (SVO) used for lithium primary batteries were chemically synthesized by an oxidative polymerization of pyrrole monomer on the SVO surface in an acidic medium. The composite electrode exhibited higher discharge capacity and better rate capability as compared with the pristine SVO electrode. The improvement in electrochemical performance of the composite electrode was due to PPy which accommodates lithium ions and also enhances the SVO utilization. Chronoamperometric and ac-impedance measurements indicated that lithium intercalation proceeds under the mixed control by interfacial charge transfer and diffusion. The enhanced SVO utilization in the composite electrode results from a facilitated kinetics of interfacial charge transfer in the presence of PPy.

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

    International Nuclear Information System (INIS)

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

    2010-01-01

    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.

  13. Surface Interrogation Scanning Electrochemical Microscopy for a Photoelectrochemical Reaction: Water Oxidation on a Hematite Surface.

    Science.gov (United States)

    Kim, Jae Young; Ahn, Hyun S; Bard, Allen J

    2018-03-06

    To understand the pathway of a photoelectrochemical (PEC) reaction, quantitative knowledge of reaction intermediates is important. We describe here surface interrogation scanning electrochemical microscopy for this purpose (PEC SI-SECM), where a light pulse to a photoactive semiconductor film at a given potential generates intermediates that are then analyzed by a tip generated titrant at known times after the light pulse. The improvements were demonstrated for photoelectrochemical water oxidation (oxygen evolution) reaction on a hematite surface. The density of photoactive sites, proposed to be Fe 4+ species, on a hematite surface was successfully quantified, and the photoelectrochemical water oxidation reaction dynamics were elucidated by time-dependent redox titration experiments. The new configuration of PEC SI-SECM should find expanded usage to understand and investigate more complicated PEC reactions with other materials.

  14. Effect of annealing temperature on electrochemical characteristics of ruthenium oxide/multi-walled carbon nanotube composites

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Min-Kang [Department of Chemistry, Inha University, 253, Incheon 402-751 (Korea, Republic of); Saouab, Abdelghani [Department of Mechanical Engineering, University of Le Havre, Place Robert Schuman, BP 4006, 76610 Le Havre (France); Park, Soo-Jin, E-mail: sjpark@inha.ac.k [Department of Chemistry, Inha University, 253, Incheon 402-751 (Korea, Republic of)

    2010-02-25

    The preparation and characterization of high-surface-area ruthenium oxide (RuO{sub 2})/multi-walled carbon nanotubes (MWCNTs) composite electrodes for use in supercapacitors is reported in this work. The RuO{sub 2}/MWCNTs composites were prepared by the polyol process of RuO{sub 2} into MWCNTs and by Ru annealing in air before mixed with MWCNTs. The chemically oxidized and annealed Ru nanoparticles contribute a pseudocapacitance to the electrodes and dramatically improve the energy storage characteristics of the MWCNTs. These composites annealed at 200 deg. C demonstrate specific capacitances in excess of 130 F/g in comparison to 80 F/g for pristine MWCNTs. The annealing temperature is found to play an important role, as it affects the electrochemical performance of annealed RuO{sub 2}/MWCNTs composites critically due to its influence on the diffusion of protons into the structure.

  15. Electrochemical synthesis of birnessite-type layered manganese oxides for rechargeable lithium batteries

    Science.gov (United States)

    Nakayama, Masaharu; Kanaya, Taku; Lee, Jong-Won; Popov, Branko N.

    Layered manganese dioxide (MnO 2) films intercalated with Li +, Na + or Mg 2+ ions were synthesized by a one-step electrochemical method. The electrodeposition was potentiostatically performed by applying an anodic potential of 1.0 V vs. Ag/AgCl in an aqueous MnSO 4 solution containing a perchlorate salt of the cation. The electrodeposited oxide films have a birnessite-type layered structure with alkali cations and water molecules between manganese oxide layers. The galvanostatic charge-discharge experiments performed in 1 M LiPF 6-DME/PC solution indicated that the Mg 2+-intercalated MnO 2 electrode exhibits an initial discharge capacity as large as 140 mAh g -1 and it shows a better capacity retention during cycling as compared with the Li +- or Na +-intercalated MnO 2 electrode.

  16. Electrochemical oxidation of loop diuretic furosemide in aqueous acid medium and its analytical application

    Directory of Open Access Journals (Sweden)

    Shikandar D. Bukkitgar

    2016-12-01

    Full Text Available An investigation of oxidative–reductive mechanisms of pharmaceutically important molecules gives us information about the metabolic fact of targeted drug. As compared to recent ongoing, time-consuming and costly techniques, there is an urgent needing for development of a sensitive technique, which can help easy understanding of these pathways. Therefore, in the present work, an effective, low-cost and time-saving technique to investigate the reaction mechanism of furosemide in aqueous acid medium is attempted. Furosemide undergoes two-proton and two-electron transfer reaction. The product obtained was analysed by UV spectra. It was found that the chemical oxidation and electrochemical oxidation of furosemide follows two different pathways. In addition, an effective technique has been developed to determine furosemide in its trace level. Good recoveries and low detection limit accomplished the magnitude of the proposed method. The proposed method was adopted for furosemide determination in human urine and pharmaceutical samples.

  17. High temperature oxidation and electrochemical investigations on nickel-base alloys

    International Nuclear Information System (INIS)

    Obigodi-Ndjeng, Georgia

    2011-01-01

    This study examined high-temperature oxidation behavior of different Ni-base alloys. In addition, electrochemical characterization of the alloy's corrosion behavior was carried out, including comparison of the properties of native passive films grown at room temperature and high temperature oxide scales. PWA 1483 (single-crystalline Ni-base superalloy) and model alloys Ni-Cr-X (where X is either Co or Al) were oxidized at 800 and 900 C in air for different time periods. The superalloy showed the best oxidation behavior at both temperatures, which might be due to the fact that the oxidation growth function is subparabolic for the model alloys and parabolic for the superalloy at 800 C. At higher temperatures, changes in the kinetics are induced, as the oxides grow faster, thus only PWA 1483 growth follows the parabolic law. Different scales in a typical sandwich form were detected, with the inner layer comprised of mostly Cr 2 O 3 , the middle layer was mixture of different oxides and spinels, depending on the alloying elements, and the oxide at the interface oxygen/oxide was found to be NiO. The influence of sample preparation could also be shown, as rougher surfaces change the oxidation kinetics from parabolic and subparabolic for polished samples to linear. The influence of moisture on the oxidation behavior of the 2 nd generation single crystal Ni-base superalloys (PWA 1484, PWA 1487, CMSX 4, Rene N5 and Rene N5+) was studied at 1000 C after 100 h oxidation period. It was found that the moisture increased the oxidation rate and mostly the transient oxides growth rate. The water vapor content in air also influenced the behavior of these alloys, as they showed a higher mass gain in air + 30% water vapor than in air + 10% water vapor. The alloys PWA 1484 and CMSX 4 showed respectively the worst and best behavior in all the studied atmospheres. The addition of reactive elements, such as Yttrium, Hafnium and Lanthanum is likely to enhance the oxidation behavior of PWA

  18. Study of the electrochemical oxidation of Am with lacunary heteropolyanions and silver nitrate

    International Nuclear Information System (INIS)

    Chartier, D.

    1999-01-01

    Electrochemical oxidation of Am(III) with certain lacunary heteropolyanions (LHPA α 2 -P 2 W 17 O 61 10- or αSiW 11 O 39 8- ) and silver nitrate is an efficient way to prepare Am(VI). This document presents bibliographic data and an experimental study of the process. Thus, it has been established that Am(IV) is an intermediate species in the reaction and occurs in 1:1 (Amt IV LHPA) or 1:2 (Am IV (LHAP) 2 ) complexes with the relevant LHPA. These 1:1 complexes of Am(IV) have been identified and isolated in this work whereas 1:2 complexes were known from previous studies. The reactivity of these complexes in oxidation shows that 1:1 complexes of Am(IV) are oxidised much more quickly than 1:2 complexes. Apparent stability constants of Am(III) and Am(IV) complexes with the relevant LHPA have been measured for a 1 M nitric acid medium. Thermodynamic data of the reaction are then assessed: redox potentials of Am pairs are computed for a 1 M nitric acid medium containing various amount of LHPA ligands. Those results show that the role of LHPA is to stabilize the intermediate species Am(IV) by lowering the Am(IV)/Am(III) pair potential of about 1 Volt. Nevertheless, if this stabilisation is too strong (i.e. of tungsto-silicate), the oxidation of Am(IV) requires high anodic potential (more than 2 V/ENH). Then, the faradic yield of the oxidation of americium is poor because of water oxidation. This study has also shown that the main role of silver is to catalyze the electrochemical oxidation of Am IV (LHPA) X complexes. Indeed, these oxidations without silver are extremely slow. An oxygen tracer experiment has been performed during the oxidation of Am(III) in Am(VI). It has been shown that the oxygen atoms of Am(VI) (AMO 2 2+ ) come from water molecules of the solvent and not from the complexing oxygen atoms of the ligands. (author)

  19. LABORATORY EVALUATION OF A MICROFLUIDIC ELECTROCHEMICAL SENSOR FOR AEROSOL OXIDATIVE LOAD.

    Science.gov (United States)

    Koehler, Kirsten; Shapiro, Jeffrey; Sameenoi, Yupaporn; Henry, Charles; Volckens, John

    2014-05-01

    Human exposure to particulate matter (PM) air pollution is associated with human morbidity and mortality. The mechanisms by which PM impacts human health are unresolved, but evidence suggests that PM intake leads to cellular oxidative stress through the generation of reactive oxygen species (ROS). Therefore, reliable tools are needed for estimating the oxidant generating capacity, or oxidative load, of PM at high temporal resolution (minutes to hours). One of the most widely reported methods for assessing PM oxidative load is the dithiothreitol (DTT) assay. The traditional DTT assay utilizes filter-based PM collection in conjunction with chemical analysis to determine the oxidation rate of reduced DTT in solution with PM. However, the traditional DTT assay suffers from poor time resolution, loss of reactive species during sampling, and high limit of detection. Recently, a new DTT assay was developed that couples a Particle-Into-Liquid-Sampler with microfluidic-electrochemical detection. This 'on-line' system allows high temporal resolution monitoring of PM reactivity with improved detection limits. This study reports on a laboratory comparison of the traditional and on-line DTT approaches. An urban dust sample was aerosolized in a laboratory test chamber at three atmospherically-relevant concentrations. The on-line system gave a stronger correlation between DTT consumption rate and PM mass (R 2 = 0.69) than the traditional method (R 2 = 0.40) and increased precision at high temporal resolution, compared to the traditional method.

  20. Porous Ni-Co-Mn oxides prisms for high performance electrochemical energy storage

    Science.gov (United States)

    Zhao, Jianbo; Li, Man; Li, Junru; Wei, Chengzhen; He, Yuyue; Huang, Yixuan; Li, Qiaoling

    2017-12-01

    Porous Ni-Co-Mn oxides prisms have been successfully synthesized via a facile route. The process involves the preparation of nickel-cobalt-manganese acetate hydroxide by a simple co-precipitation method and subsequently the thermal treatment. The as-synthesized Ni-Co-Mn oxides prisms had a large surface area (96.53 m2 g-1) and porous structure. As electrode materials for supercapacitors, porous Ni-Co-Mn oxides prisms showed a high specific capacitance of 1623.5 F g-1 at 1.0 A g-1. Moreover, the porous Ni-Co-Mn oxides prisms were also employed as positive electrode materials to assemble flexible solid-state asymmetric supercapacitors. The resulting flexible device had a maximum volumetric energy density (0.885 mW h cm-3) and power density (48.9 mW cm-3). Encouragingly, the flexible device exhibited good cycling stability with only about 2.2% loss after 5000 charge-discharge cycles and excellent mechanical stability. These results indicate that porous Ni-Co-Mn oxides prisms have the promising application in high performance electrochemical energy storage.

  1. Amine functionalized graphene oxide/CNT nanocomposite for ultrasensitive electrochemical detection of trinitrotoluene

    Energy Technology Data Exchange (ETDEWEB)

    Sablok, Kavita; Bhalla, Vijayender; Sharma, Priyanka; Kaushal, Roohi; Chaudhary, Shilpa [Institute of Microbial Technology (CSIR) Sector-39A, Chandigarh160036 (India); Suri, C. Raman, E-mail: raman@imtech.res.in [Institute of Microbial Technology (CSIR) Sector-39A, Chandigarh160036 (India)

    2013-03-15

    Highlights: ► Binding of electron-deficient trinitrotoluene to the electron rich amino groups to form JM complexes. ► rGO/CNT based platform for enhanced electrochemical detection. ► Functionalization and characterization of rGO/CNT with amine derivative. ► Ultrasenstitive and specific detection of TNT. -- Abstract: Binding of electron-deficient trinitrotoluene (TNT) to the electron rich amine groups on a substrate form specific charge-transfer Jackson–Meisenheimer (JM) complex. In the present work, we report formation of specific JM complex on amine functionalized reduced graphene oxide/carbon nanotubes- (a-rGO/CNT) nanocomposite leading to sensitive detection of TNT. The CNT were dispersed using graphene oxide that provides excellent dispersion by attaching to CNT through its hydrophobic domains and solubilizes through the available -OH and -COOH groups on screen printed electrode (SPE). The GO was reduced electrochemically to form reduced graphene that remarkably increases electrochemical properties owing to the intercalation of high aspect CNT on graphene flakes as shown by TEM micrograph. The surface amine functionalization of dropcasted and rGO/CNT was carried out using a bi-functional cross linker ethylenediamine. The extent of amine functionalization on modified electrodes was confirmed using energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS) and confocal microscopy. The FTIR and Raman spectra further suggested the formation of JM complex between amine functionalized electrodes and TNT leading to a shift in peak intensity together with peak broadening. The a-rGO/CNT nanocomposite prepared electrode surface leads to ultra-trace detection of TNT upto 0.01 ppb with good reproducibility (n = 3). The a-rGO/CNT sensing platform could be an alternate for sensitive detection of TNT explosive for various security and environmental applications.

  2. Surface-modified reduced graphene oxide electrodes for capacitors by ionic liquids and their electrochemical properties

    International Nuclear Information System (INIS)

    Kim, Jieun; Kim, Seok

    2014-01-01

    Highlights: • Reduced graphene oxide surface was modified by introduction of ionic liquids. • Microstructure and capacitance of modified electrode were dependent on the ionic liquids contents. • Modification gives electrode better charge transport and higher specific capacitance. • Modified electrode showed the better capacitive performance such as rate capability and cycle stability. - Abstract: In this work, reduced graphene oxide (rGO)/ionic liquids (IL) composites with different weight ratios of IL to rGO were synthesized by a simple method. In these composites, IL contributed to the exfoliation of rGO sheets and to the improvement of the electrochemical properties of the resulting composites by enhancing the ion diffusion and charge transport. The structure of the composites was examined by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The TEM images showed that IL was coated on the surface of rGO in a translucent manner. The electrochemical analysis of the prepared composites was carried out by performing cyclic voltammetry (CV), galvanostatic charge–discharge, and electrochemical impedance spectroscopy (EIS). Among the prepared composites, the one with a weight ratio of rGO to IL of 1:7 showed the highest specific capacitance of 147.5 F g −1 at a scan rate of 10 mV s −1 . In addition, the rate capability and cycle performance of the composites were enhanced compared to pristine rGO. These enhanced properties make the composites suitable as electrode materials for the better performance supercapacitors

  3. Amine functionalized graphene oxide/CNT nanocomposite for ultrasensitive electrochemical detection of trinitrotoluene

    International Nuclear Information System (INIS)

    Sablok, Kavita; Bhalla, Vijayender; Sharma, Priyanka; Kaushal, Roohi; Chaudhary, Shilpa; Suri, C. Raman

    2013-01-01

    Highlights: ► Binding of electron-deficient trinitrotoluene to the electron rich amino groups to form JM complexes. ► rGO/CNT based platform for enhanced electrochemical detection. ► Functionalization and characterization of rGO/CNT with amine derivative. ► Ultrasenstitive and specific detection of TNT. -- Abstract: Binding of electron-deficient trinitrotoluene (TNT) to the electron rich amine groups on a substrate form specific charge-transfer Jackson–Meisenheimer (JM) complex. In the present work, we report formation of specific JM complex on amine functionalized reduced graphene oxide/carbon nanotubes- (a-rGO/CNT) nanocomposite leading to sensitive detection of TNT. The CNT were dispersed using graphene oxide that provides excellent dispersion by attaching to CNT through its hydrophobic domains and solubilizes through the available -OH and -COOH groups on screen printed electrode (SPE). The GO was reduced electrochemically to form reduced graphene that remarkably increases electrochemical properties owing to the intercalation of high aspect CNT on graphene flakes as shown by TEM micrograph. The surface amine functionalization of dropcasted and rGO/CNT was carried out using a bi-functional cross linker ethylenediamine. The extent of amine functionalization on modified electrodes was confirmed using energy dispersive X-ray (EDX), X-ray photoelectron spectroscopy (XPS) and confocal microscopy. The FTIR and Raman spectra further suggested the formation of JM complex between amine functionalized electrodes and TNT leading to a shift in peak intensity together with peak broadening. The a-rGO/CNT nanocomposite prepared electrode surface leads to ultra-trace detection of TNT upto 0.01 ppb with good reproducibility (n = 3). The a-rGO/CNT sensing platform could be an alternate for sensitive detection of TNT explosive for various security and environmental applications

  4. Cross-flow electrochemical reactor cells, cross-flow reactors, and use of cross-flow reactors for oxidation reactions

    Science.gov (United States)

    Balachandran, Uthamalingam; Poeppel, Roger B.; Kleefisch, Mark S.; Kobylinski, Thaddeus P.; Udovich, Carl A.

    1994-01-01

    This invention discloses cross-flow electrochemical reactor cells containing oxygen permeable materials which have both electron conductivity and oxygen ion conductivity, cross-flow reactors, and electrochemical processes using cross-flow reactor cells having oxygen permeable monolithic cores to control and facilitate transport of oxygen from an oxygen-containing gas stream to oxidation reactions of organic compounds in another gas stream. These cross-flow electrochemical reactors comprise a hollow ceramic blade positioned across a gas stream flow or a stack of crossed hollow ceramic blades containing a channel or channels for flow of gas streams. Each channel has at least one channel wall disposed between a channel and a portion of an outer surface of the ceramic blade, or a common wall with adjacent blades in a stack comprising a gas-impervious mixed metal oxide material of a perovskite structure having electron conductivity and oxygen ion conductivity. The invention includes reactors comprising first and second zones seprated by gas-impervious mixed metal oxide material material having electron conductivity and oxygen ion conductivity. Prefered gas-impervious materials comprise at least one mixed metal oxide having a perovskite structure or perovskite-like structure. The invention includes, also, oxidation processes controlled by using these electrochemical reactors, and these reactions do not require an external source of electrical potential or any external electric circuit for oxidation to proceed.

  5. Advanced oxidation of acid and reactive dyes

    DEFF Research Database (Denmark)

    Arslan-Alaton, I.; Gursoy, B.H.; Schmidt, Jens Ejbye

    2008-01-01

    M) for 10:hsp sp="0.25" min Fenton treatment at pH 3, resulting in reduced chemical oxygen demand and dissolved organic carbon removal efficiencies; only acetate was detected as a stable dye oxidation end product. During anaerobic digestion, 100, 29% and no inhibition in methane production was observed...

  6. Preparing cuprous oxide nanomaterials by electrochemical method for non-enzymatic glucose biosensor

    Science.gov (United States)

    Nguyen, Thu-Thuy; Huy, Bui The; Hwang, Seo-Young; Vuong, Nguyen Minh; Pham, Quoc-Thai; Nghia, Nguyen Ngoc; Kirtland, Aaron; Lee, Yong-Ill

    2018-05-01

    Cuprous oxide (Cu2O) nanostructure has been synthesized using an electrochemical method with a two-electrode system. Cu foils were used as electrodes and NH2(OH) was utilized as the reducing agent. The effects of pH and applied voltages on the morphology of the product were investigated. The morphology and optical properties of Cu2O particles were characterized using scanning electron microscopy, x-ray diffraction, and diffuse reflectance spectra. The synthesized Cu2O nanostructures that formed in the vicinity of the anode at 2 V and pH = 11 showed high uniform distribution, small size, and good electrochemical sensing. These Cu2O nanoparticles were coated on an Indium tin oxide substrate and applied to detect non-enzyme glucose as excellent biosensors. The non-enzyme glucose biosensors exhibited good performance with high response, good selectivity, wide linear detection range, and a low detection limit at 0.4 μM. Synthesized Cu2O nanostructures are potential materials for a non-enzyme glucose biosensor.

  7. Removal of colour and COD from wastewater containing acid blue 22 by electrochemical oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Panizza, Marco [Dipartimento di Ingegneria Chimica e di Processo ' G.B. Bonino' , Universita degli Studi di Genova, p.le J.F. Kennedy 1, 16129 Genova (Italy)], E-mail: marco.panizza@unige.it; Cerisola, Giacomo [Dipartimento di Ingegneria Chimica e di Processo ' G.B. Bonino' , Universita degli Studi di Genova, p.le J.F. Kennedy 1, 16129 Genova (Italy)

    2008-05-01

    Electrochemical oxidation of synthetic wastewater containing acid blue 22 on a boron-doped diamond electrode (BDD) was studied, using cyclic voltammetry and bulk electrolysis. The influence of current density, dye concentration, flow rate, and temperature was investigated, in order to find the best conditions for COD and colour removal. It was found that, during oxidation, a polymeric film, causing BDD deactivation, was formed in the potential region of water stability, and that it was removed by anodic polarisation at high potentials in the region of O{sub 2} evolution. Bulk electrolysis results showed that the electrochemical process was suitable for completely removing COD and effectively decolourising wastewaters, due to the production of hydroxyl radicals on the diamond surface. In particular, under optimal experimental conditions of flow rates (i.e. 300 dm{sup 3} h{sup -1}) and current density (i.e. 20 mA cm{sup -2}), 97% of COD was removed in 12 h electrolysis, with 70 kWh m{sup -3}energy consumption.

  8. Removal of colour and COD from wastewater containing acid blue 22 by electrochemical oxidation

    International Nuclear Information System (INIS)

    Panizza, Marco; Cerisola, Giacomo

    2008-01-01

    Electrochemical oxidation of synthetic wastewater containing acid blue 22 on a boron-doped diamond electrode (BDD) was studied, using cyclic voltammetry and bulk electrolysis. The influence of current density, dye concentration, flow rate, and temperature was investigated, in order to find the best conditions for COD and colour removal. It was found that, during oxidation, a polymeric film, causing BDD deactivation, was formed in the potential region of water stability, and that it was removed by anodic polarisation at high potentials in the region of O 2 evolution. Bulk electrolysis results showed that the electrochemical process was suitable for completely removing COD and effectively decolourising wastewaters, due to the production of hydroxyl radicals on the diamond surface. In particular, under optimal experimental conditions of flow rates (i.e. 300 dm 3 h -1 ) and current density (i.e. 20 mA cm -2 ), 97% of COD was removed in 12 h electrolysis, with 70 kWh m -3 energy consumption

  9. Hydrothermal-reduction synthesis of manganese oxide nanomaterials for electrochemical supercapacitors.

    Science.gov (United States)

    Zhang, Xiong; Chen, Yao; Yu, Peng; Ma, Yanwei

    2010-11-01

    In the present work, amorphous manganese oxide nanomaterials have been synthesized by a common hydrothermal method based on the redox reaction between MnO4(-) and Fe(2+) under an acidic condition. The synthesized MnO2 samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and electrochemical studies. XRD results showed that amorphous manganese oxide phase was obtained. XPS quantitative analysis revealed that the atomic ratio of Mn to Fe was 3.5 in the MnO2 samples. TEM images showed the porous structure of the samples. Electrochemical properties of the MnO2 electrodes were studied using cyclic voltammetry and galvanostatic charge-discharge cycling in 1 M Na2SO4 aqueous electrolyte, which showed excellent pseudocapacitance properties. A specific capacitance of 192 Fg(-1) at a current density of 0.5 Ag(-1) was obtained at the potential window from -0.1 to 0.9 V (vs. SCE).

  10. Electrochemical promotion of oxidative coupling of methane on platinum/polybenzimidazole catalyst

    DEFF Research Database (Denmark)

    Petrushina, Irina; Bandur, Viktor; Bjerrum, Niels

    2002-01-01

    The electrochemical promotion of catalytic methane oxidation was studied using a (CH4,O-2,Ar), Pt\\polybenzimidazole (PBI)-H3PO4\\Pt,(H-2,Ar) fuel cell at 135degreesC. It has been found that C2H2, CO2, and water are the main oxidation products. Without polarization the yield of C2H2 was 0......, meaning that there was a maximum promotion effect at a polarization of -0.15 V, or 0.45 V catalyst potential vs. a hydrogen electrode (3.8% C2H2 yield). The catalytic rate enhancement ratio, r(C-2)/r(o)(C-2), at this maximum was 4.2. There was no C2H2 production at polarization greater than or equal to0.......9% and the yield of CO2 was 7.3%. This means that C-2 open-circuit selectivity was approximately 11%. Open-circuit voltage was around 0.6 V. It has been shown that the CH4 --> C2H2 catalytic reaction can be electrochemically promoted at negative polarization and exhibits a clear "volcano-type'' promotion behavior...

  11. Treatment of a Textile Effluent by Electrochemical Oxidation and Coupled System Electooxidation–Salix babylonica

    Directory of Open Access Journals (Sweden)

    Alejandra Sánchez-Sánchez

    2018-01-01

    Full Text Available The removal of pollutants from textile wastewater via electrochemical oxidation and a coupled system electrooxidation—Salix babylonica, using boron-doped diamond electrodes was evaluated. Under optimal conditions of pH 5.23 and 3.5 mA·cm−2 of current density, the electrochemical method yields an effective reduction of chemical oxygen demand by 41.95%, biochemical oxygen demand by 83.33%, color by 60.83%, and turbidity by 26.53% at 300 minutes of treatment. The raw and treated wastewater was characterized by infrared spectroscopy to confirm the degradation of pollutants. The wastewater was oxidized at 15-minute intervals for one hour and was placed in contact with willow plants for 15 days. The coupled system yielded a reduction of the chemical oxygen demand by 14%, color by 85%, and turbidity by 93%. The best efficiency for the coupled system was achieved at 60 minutes, at which time the plants achieved more biomass and photosynthetic pigments.

  12. Supported versus colloidal zinc oxide for advanced oxidation processes

    Science.gov (United States)

    Laxman, Karthik; Al Rashdi, Manal; Al Sabahi, Jamal; Al Abri, Mohammed; Dutta, Joydeep

    2017-07-01

    Photocatalysis is a green technology which typically utilizes either supported or colloidal catalysts for the mineralization of aqueous organic contaminants. Catalyst surface area and surface energy are the primary factors determining its efficiency, but correlation between the two is still unclear. This work explores their relation and hierarchy in a photocatalytic process involving both supported and colloidal catalysts. In order to do this the active surface areas of supported zinc oxide nanorods (ZnO NR's) and colloidal zinc oxide nanoparticles (having different surface energies) were equalized and their phenol oxidation mechanism and capacity was analyzed. It was observed that while surface energy had subtle effects on the oxidation rate of the catalysts, the degradation efficiency was primarily a function of the surface area; which makes it a better parameter for comparison when studying different catalyst forms of the same material. Thus we build a case for the use of supported catalysts, wherein their catalytic efficiency was tested to be unaltered over several days under both natural and artificial light, suggesting their viability for practical applications.

  13. Effects of electrochemical-deposition method and microstructure on the capacitive characteristics of nano-sized manganese oxide

    International Nuclear Information System (INIS)

    Shinomiya, Takuya; Gupta, Vinay; Miura, Norio

    2006-01-01

    The amorphous nano-structured manganese oxide was electrochemically deposited onto a stainless-steel electrode. The structure and surface morphology of the obtained manganese oxide were studied by means of X-ray diffraction analysis and scanning electron microscopy. The capacitive characteristics of the manganese oxide electrodes were investigated by means of cyclic voltammetry and constant current charge-discharge cycling. The morphological and capacitive characteristics of the hydrous manganese oxide was found to be strongly influenced by the electrochemical deposition conditions. The highest specific capacitance value of ca. 410 F g -1 and the specific power of ca. 54 kW kg -1 were obtained at 400 mV s -1 sweep rate of potentiodynamic deposition condition. The cyclic-life data showed that the specific capacitance was highly stable up to 10,000 cycles examined. This suggests the excellent cyclic stability of the obtained amorphous hydrous manganese oxide for supercapacitor application

  14. Effects of electrochemical-deposition method and microstructure on the capacitive characteristics of nano-sized manganese oxide

    Energy Technology Data Exchange (ETDEWEB)

    Shinomiya, Takuya; Gupta, Vinay; Miura, Norio [Art, Science and Technology Center for Cooperative Research, Kyushu University, Kasuga-shi, Fukuoka 816-8580 (Japan)

    2006-06-01

    The amorphous nano-structured manganese oxide was electrochemically deposited onto a stainless-steel electrode. The structure and surface morphology of the obtained manganese oxide were studied by means of X-ray diffraction analysis and scanning electron microscopy. The capacitive characteristics of the manganese oxide electrodes were investigated by means of cyclic voltammetry and constant current charge-discharge cycling. The morphological and capacitive characteristics of the hydrous manganese oxide was found to be strongly influenced by the electrochemical deposition conditions. The highest specific capacitance value of ca. 410Fg{sup -1} and the specific power of ca. 54kWkg{sup -1} were obtained at 400mVs{sup -1} sweep rate of potentiodynamic deposition condition. The cyclic-life data showed that the specific capacitance was highly stable up to 10,000 cycles examined. This suggests the excellent cyclic stability of the obtained amorphous hydrous manganese oxide for supercapacitor application. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Linjie [School of Pharmacy, Lanzhou University, Lanzhou 730000 (China); Gou, Yuqiang [Lanzhou Military Command Center for Disease Prevention and Control, Lanzhou 730000 (China); Gao, Xia; Zhang, Pei; Chen, Wenxia; Feng, Shilan [School of Pharmacy, Lanzhou University, Lanzhou 730000 (China); Hu, Fangdi, E-mail: hufd@lzu.edu.cn [School of Pharmacy, Lanzhou University, Lanzhou 730000 (China); Li, Yingdong, E-mail: lydj412@163.com [Gansu College of Tradition Chinese Medicine, Lanzhou 730000 (China)

    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 (k{sub s}) and electron-transfer coefficient (α) were calculated as 1.12, 1.24 s{sup −1}, and 0.40, respectively. Under the optimized conditions, the oxidation peak current was proportional to FA concentration at 8.49 × 10{sup −8} mol L{sup −1} to 3.89 × 10{sup −5} mol L{sup −1} with detection limit of 2.06 × 10{sup −8} mol L{sup −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%. - Highlights: • A novel ERGO–based electrochemical sensor of FA was successfully fabricated by using one-step electrodeposition method. • The electrode reaction was an adsorption–diffusion mixed controlled process. • The low detection limit with good selectivity and sensitivity were obtained. • This method was applied for the determination of FA in A. sinensis and biological samples.

  16. Tuning inner-layer oxygen functional groups of reduced graphene oxide by potentiostatic oxidation for high performance electrochemical energy storage devices

    International Nuclear Information System (INIS)

    Wang, Huixin; Feng, Bingmei; Ye, Yifan; Guo, Jinghua; Fang, Hai-Tao

    2017-01-01

    Graphical abstract: Tuning inner-layer oxygen functional groups of reduced graphene oxide by potentiostatic oxidation in carbonate-based electrolyte improves the electrochemical performance. - Abstract: The electrochemical lithiation/delithiation of oxygen-containing functional groups (OCFGs) of nanocarbon materials, particularly graphene, have attracted intensive interest in recent years. Here, we propose a controllable potentiostatic oxidation approach to tune the OCFGs of as-prepared reduced graphene oxide (rGO) in a carbonate-based electrolyte to improve the specific capacity and rate capability. By X-Ray absorption spectroscopy in total fluorescence yield mode and X-Ray diffraction, we confirm that potentiostatic oxidations generate new OCFGs in the inner-layer of rGO. The content of OCFGs increases as oxidation potential being elevated. Such increasing of OCFGs in quantity significantly enhances the capacity. For instance, the specific capacity of 170.4 mAh g −1 for pristine rGO electrode is increased to 290.5 mAh g −1 after the oxidation at 5.0 V. We demonstrate that oxidations at moderate potentials can reduce the electrochemical and ohmic polarizations of rGO electrodes without deteriorating diffusion dynamic, thereby improving rate capability. After the optimal oxidation at 4.7 V, rGO electrode exhibits an excellent rate capability, delivering 58.4 mAh g −1 at 20 A g −1 .

  17. NEW INSIGTHS ON THE KINETICS AND MECHANISM OF THE ELECTROCHEMICAL OXIDATION OF DICLOFENAC IN NEUTRAL AQUEOUS MEDIUM

    International Nuclear Information System (INIS)

    Cid-Cerón, M.M.; Guzmán-Hernández, D.S.; Ramírez-Silva, M.T.; Galano, A.; Romero-Romo, M.; Palomar-Pardavé, M.

    2016-01-01

    Highlights: • DCF electrochemical oxidation was studied from aqueous solution with a CPE. • Both stagnant and forced convection conditions were considered. • We found DCF electrochemical oxidation is a mass transfer-controlled process. • An EC mechanism was found where the electrodic is quasi-reversible. • C reaction provokes the breaking up the DCF through the nitrogen atom. • DCF diffusion coefficient was experimental and theoretically calculated. - Abstract: The diclofenac (DCF) electrochemical oxidation mechanism was studied through: linear voltammetry (LV), chronoamperometry (CA) sampled-current voltammetry (SCV), potentiostatic coulometry (PC) cyclic voltammetry (CV) under stagnant conditions and linear voltammetry under forced convection conditions (FCLV) over a carbon paste electrode (CPE) from an aqueous medium containing 0.1 M phosphate buffer at pH 7. It was found that the DCF electrochemical oxidation involves an EC mechanism, where the electrochemical reaction is carried out through a one electron-exchange while the chemical reaction involves breaking up the DCF through the nitrogen atom, thereby generating the fragments 2,6 dichloroaniline and 2-(2hydroxyprop-2-enyl)phenol. Reverting the potential scan in the cathodic direction at different scan rates and regardless of its rate, after the oxidation peak, it was found that it was possible to reduce only 38% of the DCF oxidized. The spectrophotometric study carried out during different macro-electrolysis periods allowed observing that the current decrease of the oxidation peak coupled to the DCF absorption (at 270 nm), together with the development of a new spectrophotometric absorption maximum (450 nm), all confirm the EC mechanism proposed. With the use of several experimental techniques (CA, LV and FCLV) and theoretical ones using the Stokes–Einstein approach, the DCF diffusion coefficient was determined, this being in average 8.1 × 10"−"6 cm"2 s"−"1.

  18. Tuning the Electronic Structure of Titanium Oxide Support to Enhance the Electrochemical Activity of Platinum Nanoparticles

    KAUST Repository

    Shi, Feifei

    2013-09-11

    Two times higher activity and three times higher stability in methanol oxidation reaction, a 0.12 V negative shift of the CO oxidation peak potential, and a 0.07 V positive shift of the oxygen reaction potential compared to Pt nanoparticles on pristine TiO2 support were achieved by tuning the electronic structure of the titanium oxide support of Pt nanoparticle catalysts. This was accomplished by adding oxygen vacancies or doping with fluorine. Experimental trends are interpreted in the context of an electronic structure model, showing an improvement in electrochemical activity when the Fermi level of the support material in Pt/TiOx systems is close to the Pt Fermi level and the redox potential of the reaction. The present approach provides guidance for the selection of the support material of Pt/TiOx systems and may be applied to other metal-oxide support materials, thus having direct implications in the design and optimization of fuel cell catalyst supports. © 2013 American Chemical Society.

  19. Fabrication of ultrafine manganese oxide-decorated carbon nanofibers for high-performance electrochemical capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Ying; Lee, Sungsik; Brown, Dennis E.; Zhao, Hairui; Li, Xinsong; Jiang, Daqiang; Hao, Shijie; Zhao, Yongxiang; Cong, Daoyong; Zhang, Xin; Ren, Yang

    2016-09-01

    Ultrafine manganese oxide-decorated carbon nanofibers (MnOn-CNF) as a new type of electrode materials are facilely fabricated by direct conversion of Mn, Zn-trimesic acid (H3BTC) metal organic framework fibers (Mn-ZnBTC). The construction and evolution of Mn-ZnBTC precursors are investigated by SEM and in situ high-energy XRD. The manganese oxides are highly dispersed onto the porous carbon nanofibers formed simultaneously, verified by TEM, X-ray absorption fine structure (XAFS), Raman, ICP-AES and N2 adsorption techniques. As expected, the resulting MnOn-CNF composites are highly stable, and can be cycled up to 5000 times with a high capacitance retention ratio of 98% in electrochemical capacitor measurements. They show a high capacitance of up to 179 F g–1 per mass of the composite electrode, and a remarkable capacitance of up to 18290 F g–1 per active mass of the manganese(IV) oxide, significantly exceeding the theoretical specific capacitance of manganese(IV) oxide (1370 F g–1). The maximum energy density is up to 19.7 Wh kg–1 at the current density of 0.25 A g–1, even orders higher than those of reported electric double-layer capacitors and pseudocapacitors. The excellent capacitive performance can be ascribed to the joint effect of easy accessibility, high porosity, tight contact and superior conductivity integrated in final MnOn-CNF composites.

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

    Directory of Open Access Journals (Sweden)

    Xi Lifei

    2011-01-01

    Full Text Available Abstract 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.

  1. Novel quasi-symmetric solid oxide fuel cells with enhanced electrochemical performance

    KAUST Repository

    Chen, Yonghong

    2016-02-16

    Symmetrical solid oxide fuel cell (SSOFC) using same materials as both anode and cathode simultaneously has gained extensively attentions, which can simplify fabrication process, minimize inter-diffusion between components, enhance sulfur and coking tolerance by operating the anode as the cathode in turn. With keeping the SSOFC\\'s advantages, a novel quasi-symmetrical solid oxide fuel cell (Q-SSOFC) is proposed to further improve the performance, which optimally combines two different SSOFC electrode materials as both anode and cathode simultaneously. PrBaFe2O5+δ (PBFO) and PrBaFe1.6Ni0.4O5+δ (PBFNO, Fe is partially substituted by Ni.) are prepared and applied as both cathode and anode for SSOFC, which exhibit desirable chemical and thermal compatibility with Sm0.8Ce0.2O1.9 (SDC) electrolyte. PBFO cathode exhibits higher oxygen reduction reaction (ORR) activity than PBFNO cathode in air, whereas PBFNO anode exhibits higher hydrogen oxidation reaction (HOR) activity than PBFO anode in H2. The as-designed Q-SSOFC of PBFNO/SDC/PBFO exhibits higher electrochemical performance than the conventional SSOFCs of both PBFO/SDC/PBFO and PBFNO/SDC/PBFNO. The superior performance of Q-SSOFC is attributed to the lowest polarization resistance (Rp). The newly developed Q-SSOFCs open doors for further improvement of electrochemical performance in SSOFC, which hold more promise for various potential applications. © 2016 Elsevier B.V. All rights reserved.

  2. Fundamental Insights into Propionate Oxidation in Microbial Electrolysis Cells Using a Combination of Electrochemical, Molecular biology and Electron Balance Approaches

    KAUST Repository

    Rao, Hari Ananda

    2016-11-01

    Increasing demand for freshwater and energy is pushing towards the development of alternative technologies that are sustainable. One of the realistic solutions to address this is utilization of the renewable resources like wastewater. Conventional wastewater treatment processes can be highly energy demanding and can fails to recover the full potential of useful resources such as energy in the wastewater. As a consequence, there is an urgent necessity for sustainable wastewater treatment technologies that could harness such resources present in wastewaters. Advanced treatment process based on microbial electrochemical technologies (METs) such as microbial fuel cells (MFCs) and microbial electrolysis cells (MECs) have a great potential for the resources recovery through a sustainable wastewater treatment process. METs rely on the abilities of microorganisms that are capable of transferring electrons extracellularly by oxidizing the organic matter in the wastewater and producing electrical current for electricity generation (MFC) or H2 and CH4 production (MEC). Propionate is an important volatile fatty acid (VFA) (24-70%) in some wastewaters and accumulation of this VFA can cause a process failure in a conventional anaerobic digestion (AD) system. To address this issue, MECs were explored as a novel, alternative wastewater treatment technology, with a focus on a better understanding of propionate oxidation in the anode of MECs. Having such knowledge could help in the development of more robust and efficient wastewater treatment systems to recover energy and produce high quality effluents. Several studies were conducted to: 1) determine the paths of electron flow in the anode of propionate fed MECs low (4.5 mM) and high (36 mM) propionate concentrations; 2) examine the effect of different set anode potentials on the electrochemical performance, propionate degradation, electron fluxes, and microbial community structure in MECs fed propionate; and 3) examine the temporal

  3. Materials for electrochemical capacitors

    Science.gov (United States)

    Simon, Patrice; Gogotsi, Yury

    2008-11-01

    Electrochemical capacitors, also called supercapacitors, store energy using either ion adsorption (electrochemical double layer capacitors) or fast surface redox reactions (pseudo-capacitors). They can complement or replace batteries in electrical energy storage and harvesting applications, when high power delivery or uptake is needed. A notable improvement in performance has been achieved through recent advances in understanding charge storage mechanisms and the development of advanced nanostructured materials. The discovery that ion desolvation occurs in pores smaller than the solvated ions has led to higher capacitance for electrochemical double layer capacitors using carbon electrodes with subnanometre pores, and opened the door to designing high-energy density devices using a variety of electrolytes. Combination of pseudo-capacitive nanomaterials, including oxides, nitrides and polymers, with the latest generation of nanostructured lithium electrodes has brought the energy density of electrochemical capacitors closer to that of batteries. The use of carbon nanotubes has further advanced micro-electrochemical capacitors, enabling flexible and adaptable devices to be made. Mathematical modelling and simulation will be the key to success in designing tomorrow's high-energy and high-power devices.

  4. Highly efficient and energy-saving sectional treatment of landfill leachate with a synergistic system of biochemical treatment and electrochemical oxidation on a boron-doped diamond electrode

    International Nuclear Information System (INIS)

    Zhao Guohua; Pang Yaning; Liu Lei; Gao Junxia; Lv Baoying

    2010-01-01

    In this paper, a synergistic combination of the biochemical treatment and electrochemical oxidation (SBEO) of landfill leachate with sectional treatment on a boron-doped diamond (BDD) electrode is proposed. The first stage involves the synergistic system of biochemical treatment and electrochemical oxidation. Then, the second stage is followed by individual biochemical treatment. Comparisons among the SBEO, electrochemical oxidation, biochemical treatment and biochemical treatment with the pretreatment of electrochemical oxidation are made systematically, which show that this method is both highly efficient and energy-saving. The higher TOC removal and low energy cost on the BDD electrode can be explained by the conversion of the bio-refractory pollutants to biodegradable organics in the electrochemical oxidation process, improving the current efficiency and reducing the energy cost. The treated wastewater is degraded only with biochemical treatment in the second stage, which further improves efficiency and reduced the energy cost.

  5. Enhancing the water oxidation activity of Ni2P nanocatalysts by iron-doping and electrochemical activation

    International Nuclear Information System (INIS)

    Liu, Guang; He, Dongying; Yao, Rui; Zhao, Yong; Li, Jinping

    2017-01-01

    Highlights: •A sol-gel method for synthesis of Fe-doping Ni 2 P nanocatalysts was present. •Fe-doping Ni 2 P sample exhibited high OER activity after electrochemical activation. •In situ formed Fe-NiOOH layer on activated Fe-Ni 2 P provided more active OER sites. -- Abstract: In this work, we reported a facile and safe route for synthesis of Ni 2 P nanocatalysts by sol-gel method and demonstrated that the oxygen evolution reaction (OER) activity of Ni 2 P nanocatalysts can be dramatically enhanced by iron-doping and electrochemical activation. Compared with the fresh Fe-doped Ni 2 P nanocatalysts, a stable Fe-NiOOH layer was formed on the surface of Fe-doped Ni 2 P nanoparticles by electrochemical activation, thus promoting the charge transfer ability and surface electrochemically active sites generation for the electrochemical activated Fe-doped Ni 2 P nanocatalysts, ultimately accounting for the improvement of water oxidation activity, which was evidenced by cyclic voltammograms (CV), electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectra (XPS) as well as high-resolution transmission electron microscopy (HR-TEM) measurements. For water oxidation reaction in 1 M KOH solution, the electrochemical activated Fe-doped Ni 2 P nanocatalysts can attain 10 mA/cm 2 at an overpotential of 292 mV with Tafel slope of 50 mV/dec, which was also much better than that of individual Ni 2 P, Fe 2 P nanocatalysts as well as commercial RuO 2 electrocatalyst. Moreover, long-term stability performance by chronoamperometric and chronopotentiometric tests for the activated Fe-doped Ni 2 P nanocatalysts exhibited no obvious decline within 56 h. It was demonstrated that modulating the OER catalytic activity for metal phosphide by iron-doping and electrochemical activation may provide new opportunities and avenues to engineer high performance electrocatalysts for water splitting.

  6. A Study on Electrochemical Reduction of Rare Earth Oxides in Molten LiCl-Li{sub 2}O Salt

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Min Woo; Jeong, Sang Mun; Lee, See Hoon [Chungbook National University, Chungju (Korea, Republic of); Sohn, Jung Min [Chonbuk National University, Jeonju (Korea, Republic of)

    2016-05-15

    In this study, the electrochemical reduction of RE{sub 2}O{sub 3} (RE = Nd or Ce) has been conducted via co-reduction NiO to increase the reduction degree of the rare earth oxides in molten molten LiCl containing 1wt% Li{sub 2}O. The electrochemical reduction behavior of the mixed RE{sub 2}O{sub 3}-NiO oxide has been investigated and the reduction path of RE{sub 2}O{sub 3} has been proposed. An electorchemical spent fuel processing technology, pyroprocessing, has been developed for recycling of spent fuel to be applied to a sodium-cooled fast reactor. The spent fuel is reduced in the oxide reduction process. It is well known that the rare earth oxides are hardly reduced due to their electrochemical and thermodynamic stability. The rare earth oxides unreduced in the reduction process can cause problems via reaction with UCl{sub 3} in the electrorefiner. To tackle those problems, the electrochemical reduction of rare earth oxide has been conducted via co-reduction of NiO in LiCl molten salt containing 1 wt% Li{sub 2}O. The reduction of the oxide mixture starts from the reduction of NiO to Ni, followed by that of RE{sub 2}O{sub 3} on the produced Ni to form intermetallic RENi{sub 5}. The mixed oxide pellets were successfully reduced to the RENi5 alloy by constant electrolysis at 3.0 V at 650 .deg. C. The crucial aspect to these results is that the thermodynamically stable rare-earth oxide, Nd{sub 2}O{sub 3} was successfully converted to the metal in the presence of NiO.

  7. A Study on Electrochemical Reduction of Rare Earth Oxides in Molten LiCl-Li2O Salt

    International Nuclear Information System (INIS)

    Lee, Min Woo; Jeong, Sang Mun; Lee, See Hoon; Sohn, Jung Min

    2016-01-01

    In this study, the electrochemical reduction of RE 2 O 3 (RE = Nd or Ce) has been conducted via co-reduction NiO to increase the reduction degree of the rare earth oxides in molten molten LiCl containing 1wt% Li 2 O. The electrochemical reduction behavior of the mixed RE 2 O 3 -NiO oxide has been investigated and the reduction path of RE 2 O 3 has been proposed. An electorchemical spent fuel processing technology, pyroprocessing, has been developed for recycling of spent fuel to be applied to a sodium-cooled fast reactor. The spent fuel is reduced in the oxide reduction process. It is well known that the rare earth oxides are hardly reduced due to their electrochemical and thermodynamic stability. The rare earth oxides unreduced in the reduction process can cause problems via reaction with UCl 3 in the electrorefiner. To tackle those problems, the electrochemical reduction of rare earth oxide has been conducted via co-reduction of NiO in LiCl molten salt containing 1 wt% Li 2 O. The reduction of the oxide mixture starts from the reduction of NiO to Ni, followed by that of RE 2 O 3 on the produced Ni to form intermetallic RENi 5 . The mixed oxide pellets were successfully reduced to the RENi5 alloy by constant electrolysis at 3.0 V at 650 .deg. C. The crucial aspect to these results is that the thermodynamically stable rare-earth oxide, Nd 2 O 3 was successfully converted to the metal in the presence of NiO.

  8. Electrochemical behaviour of carbon paste electrodes enriched with tin oxide nanoparticles using voltammetry and electrochemical impedance spectroscopy.

    Science.gov (United States)

    Muti, Mihrican; Erdem, Arzum; Caliskan, Ayfer; Sınag, Ali; Yumak, Tugrul

    2011-08-01

    The effect of the SnO(2) nanoparticles (SNPs) on the behaviour of voltammetric carbon paste electrodes were studied for possible use of this material in biosensor development. The electrochemical behaviour of SNP modified carbon paste electrodes (CPE) was first investigated by using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. The performance of the SNP modified electrodes were compared to those of unmodified ones and the parameters affecting the response of the modified electrode were optimized. The SNP modified electrodes were then tested for the electrochemical sensing of DNA purine base adenine to explore their further development in biosensor applications. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Electrochemical and morphological analyses on the titanium surface modified by shot blasting and anodic oxidation processes

    Energy Technology Data Exchange (ETDEWEB)

    Szesz, Eduardo M., E-mail: eszesz@neoortho.com.br [Neoortho Research Institute, Rua Ângelo Domingos Durigan, 607-Cascatinha, CEP 82025-100 Curitiba, PR (Brazil); Pereira, Bruno L., E-mail: brnl7@hotmail.com [Physics Department, Universidade Federal do Paraná, 81531-980 Curitiba, PR (Brazil); Kuromoto, Neide K., E-mail: kuromoto@fisica.ufpr.br [Physics Department, Universidade Federal do Paraná, 81531-980 Curitiba, PR (Brazil); Marino, Claudia E.B., E-mail: claudiamarino@yahoo.com [Mechanical Engineering Department, Universidade Federal do Paraná, 81531-980 Curitiba, PR (Brazil); Souza, Gelson B. de, E-mail: gelsonbs@uepg.br [Physics Department, Universidade Estadual de Ponta Grossa, 84051-510 Ponta Grossa, PR (Brazil); Soares, Paulo, E-mail: pa.soares@pucpr.br [Mechanical Engineering Department, Pontifícia Universidade Católica do Paraná, 80215-901 Curitiba, PR (Brazil)

    2013-01-01

    In recent years, many surface modification processes have been developed in order to induce the osseointegration on titanium surface and thus to improve the implants' biocompatibility. In this work, Ti surface has been modified by shot blasting followed by anodic oxidation process in order to associate the good surface characteristics of both processes to obtain a rough and porous surface able to promote the titanium surface bioactivity. Commercially pure titanium (grade 2) plates were used on the surface treatments that were as follows: Shot blasting (SB) performed using alumina (Al{sub 2}O{sub 3}) particles, and anodic oxidation (AO) using NaOH electrolyte. The morphology, structural changes and the open-circuit potentials (OCP) of the surfaces were analyzed. It can be observed that an increase on the roughness of the blasted surface and a rough and porous surface happens after the AO process. The anodic film produced is thin and followed the blasted surface topography. It can be observed that there are small pores with regular shape covering the entire surface. X-ray diffraction results showed the presence of the anatase and rutile phases on the blasted and anodized surface after heat treatment at 600 °C/1 h. Concerning electrochemical measurements, when the different samples were submitted to open-circuit conditions in a physiological electrolyte, the protective effect increases with the oxidation process due to the oxide layer. When the surface was blasted, the OCP was more negative when compared with the Ti surface without surface treatments. - Highlights: ► A combination of shot blasting and anodic oxidation surface treatments is proposed. ► Both processes produced an increase in roughness compared to the polished surface. ► The combination of processes produced a rough and porous surface. ► Open circuit results show that the protective effect increases with oxidation process. ► The combination of processes presents the better results in this

  10. Revisiting the electrochemical oxidation of ammonia on carbon-supported metal nanoparticle catalysts

    International Nuclear Information System (INIS)

    Li, Zhe-Fei; Wang, Yuxuan; Botte, Gerardine G.

    2017-01-01

    Highlights: • A procedure to pretreat electrocatalysts to study the ammonia oxidation is provided. • N ads and O/OH ads were identified as the major deactivation species that prevent ammonia oxidatoin. • The electrocatalytic activity, thermodynamics, and possible deactivation mechanisms for ammonia oxidation were elucidated. • The onset potential for ammonia oxidation is related to the hydrogen binding energy of the catalyst. • Ammonia electro-oxidation involves a complex decoupled electron and proton transfer process. - Abstract: The ammonia electro-oxidation reaction (AOR) has been studied due to its promising applications in ammonia electrolysis, wastewater remediation, direct ammonia fuel cells, and sensors. However, it is difficult to compare and analyze the reported electrocatalytic activity of AOR reliably, likely due to the variation in catalyst synthesis, electrode composition, electrode morphology, and testing protocol. In this paper, the electro-oxidation of ammonia on different carbon-supported precious metal nanoparticle catalysts was revisited. The effect of experimental conditions, electrochemical test parameters, electrocatalytic activity, thermodynamics, and possible deactivation mechanism of the catalysts were investigated. Pt/C catalyst possesses the highest electrocatalytic activity, while Ir/C and Rh/C show lower overpotential. The onset potential of the AOR is related to the hydrogen binding energy of the catalyst. N ads is one major cause of deactivation accompanied with the formation of surface O/OH ads at high potentials. The coulombic efficiency of N ads formation on Pt is about 1% initially and gradually decreases with reaction time. Increase in ammonia concentration leads to increase in current density, while increase in hydroxyl ions concentration can enhance the current density and reduce the overpotential simultaneously. The slopes of AOR onset potential and hydrogen adsorption/desorption potential of Pt/C as a function of p

  11. Electrochemical oxidation of synthetic tannery wastewater in chloride-free aqueous media

    International Nuclear Information System (INIS)

    Costa, Carla Regina; Montilla, Francisco; Morallon, Emilia; Olivi, Paulo

    2010-01-01

    The electrochemical treatment of a synthetic tannery wastewater, prepared with several compounds used by finishing tanneries, was studied in chloride-free media. Boron-doped diamond (Si/BDD), antimony-doped tin dioxide (Ti/SnO 2 -Sb), and iridium-antimony-doped tin dioxide (Ti/SnO 2 -Sb-Ir) were evaluated as anode. The influence of pH and current density on the treatment was assessed by means of the parameters used to measure the level of organic contaminants in the wastewater; i.e., total phenols, chemical oxygen demand (COD), total organic carbon (TOC), and absorbance. Results showed that faster decrease in these parameters occurred when the Si/BDD anode was used. Good results were obtained with the Ti/SnO 2 -Sb anode, but its complete deactivation was reached after 4 h of electrolysis at 25 mA cm -2 , indicating that the service life of this electrode is short. The Ti/SnO 2 -Sb-Ir anode is chemically and electrochemically more stable than the Ti/SnO 2 -Sb anode, but it is not suitable for the electrochemical treatment under the studied conditions. No significant changes were observed for electrolyses performed at different pH conditions with Si/BDD, and this electrode led to almost complete mineralization after 4 h of electrolysis at 100 mA cm -2 . The increase in current density resulted in faster wastewater oxidation, with lower current efficiency and higher energy consumption. Si/BBD proved to be the best electrodic material for the direct electrooxidation of tannery wastewaters.

  12. Effect of morphology and defect density on electron transfer of electrochemically reduced graphene oxide

    International Nuclear Information System (INIS)

    Zhang, Yan; Hao, Huilian; Wang, Linlin

    2016-01-01

    Highlights: • Different morphologies of ERGO on the surface of GCE were prepared via different methods. • The defect densities of ERGO were controlled by tuning the mass or concentration of GO. • A higher defect density of ERGO accelerates electron transfer rate. • ERGO with more exposed edge planes shows significantly higher electron transfer kinetics. • Both edge planes and defect density contribute to electron transfer of ERGO. - Abstract: Electrochemically reduced graphene oxide (ERGO) is widely used to construct electrochemical sensors. Understanding the electron transfer behavior of ERGO is essential for its electrode material applications. In this paper, different morphologies of ERGO were prepared via two different methods. Compared to ERGO/GCEs prepared by electrochemical reduction of pre-deposited GO, more exposed edge planes of ERGO are observed on the surface of ERGO-GCE that was constructed by electrophoretic deposition of GO. The defect densities of ERGO were controlled by tuning the mass or concentration of GO. The electron transfer kinetics (k"0) of GCE with different ERGOs was comparatively investigated. Owing to increased surface areas and decreased defect density, the k"0 values of ERGO/GCE initially increase and then decrease with incrementing of GO mass. When the morphology and surface real areas of ERGO-GCE are the same, an increased defect density induces an accelerated electron transfer rate. k"0 valuesof ERGO-GCEs are about 1 order of magnitude higher than those of ERGO/GCEs due to the difference in the amount of edge planes. This work demonstrates that both defect densities and edge planes of ERGO play crucial roles in electron transfer kinetics.

  13. Effect of morphology and defect density on electron transfer of electrochemically reduced graphene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yan, E-mail: yanzhang@sues.edu.cn [School of Material Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Hao, Huilian, E-mail: huilian.hao@sues.edu.cn [School of Material Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China); Wang, Linlin, E-mail: wlinlin@mail.ustc.edu.cn [College of Chemistry and Chemical Engineering, Shanghai University of Engineering Science, Shanghai 201620 (China)

    2016-12-30

    Highlights: • Different morphologies of ERGO on the surface of GCE were prepared via different methods. • The defect densities of ERGO were controlled by tuning the mass or concentration of GO. • A higher defect density of ERGO accelerates electron transfer rate. • ERGO with more exposed edge planes shows significantly higher electron transfer kinetics. • Both edge planes and defect density contribute to electron transfer of ERGO. - Abstract: Electrochemically reduced graphene oxide (ERGO) is widely used to construct electrochemical sensors. Understanding the electron transfer behavior of ERGO is essential for its electrode material applications. In this paper, different morphologies of ERGO were prepared via two different methods. Compared to ERGO/GCEs prepared by electrochemical reduction of pre-deposited GO, more exposed edge planes of ERGO are observed on the surface of ERGO-GCE that was constructed by electrophoretic deposition of GO. The defect densities of ERGO were controlled by tuning the mass or concentration of GO. The electron transfer kinetics (k{sup 0}) of GCE with different ERGOs was comparatively investigated. Owing to increased surface areas and decreased defect density, the k{sup 0} values of ERGO/GCE initially increase and then decrease with incrementing of GO mass. When the morphology and surface real areas of ERGO-GCE are the same, an increased defect density induces an accelerated electron transfer rate. k{sup 0} valuesof ERGO-GCEs are about 1 order of magnitude higher than those of ERGO/GCEs due to the difference in the amount of edge planes. This work demonstrates that both defect densities and edge planes of ERGO play crucial roles in electron transfer kinetics.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-07-01

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

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

    International Nuclear Information System (INIS)

    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

  16. Influence of oxidation level on capacitance of electrochemical capacitors fabricated with carbon nanotube/carbon paper composites

    International Nuclear Information System (INIS)

    Hsieh, C.-T.; Chen, W.-Y.; Cheng, Y.-S.

    2010-01-01

    Gaseous oxidation of carbon papers (CPs) decorated with carbon nanotubes (CNTs) with varying degrees of oxidation was conducted to investigate the influence of surface oxides on the performance of electrochemical capacitors fabricated with oxidized CNT/CP composites. The oxidation period was found to significantly enhance the O/C atomic ratio on the composites, and the increase in oxygen content upon oxidation is mainly contributed by the formation of C=O and C-O groups. The electrochemical behavior of the capacitors was tested in 1 M H 2 SO 4 within a potential of 0 and 1 V vs. Ag/AgCl. Both superhydrophilicity and specific capacitance of the oxidized CNT/CP composites were found to increase upon oxidation treatment. A linearity increase of capacitance with O/C ratio can be attributed to the increase of the population of surface oxides on CNTs, which imparts excess sites for redox reaction (pseudocapacitance) and for the formation of double-layer (double-layer capacitance). The technique of ac impedance combined with equivalent circuit clearly showed that oxidized CNT/CP capacitor imparts not only enhanced capacitance but also a low equivalent series resistance.

  17. Spin coated versus dip coated electrochromic tungsten oxide films: Structure, morphology, optical and electrochemical properties

    International Nuclear Information System (INIS)

    Deepa, M.; Saxena, T.K.; Singh, D.P.; Sood, K.N.; Agnihotry, S.A.

    2006-01-01

    A sol-gel derived acetylated peroxotungstic acid sol encompassing 4 wt.% of oxalic acid dihydrate (OAD) has been employed for the deposition of tungsten oxide (WO 3 ) films by spin coating and dip coating techniques, in view of smart window applications. The morphological and structural evolution of the as-deposited spin and dip coated films as a function of annealing temperature (250 and 500 o C) has been examined and compared by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). A conspicuous feature of the dip coated film (annealed at 250 o C) is that its electrochromic and electrochemical properties ameliorate with cycling without degradation in contrast to the spin coated film for which these properties deteriorate under repetitive cycling. A comparative study of spin and dip coated nanostructured thin films (annealed at 250 o C) revealed a superior performance for the cycled dip coated film in terms of higher transmission modulation and coloration efficiency in solar and photopic regions, faster switching speed, higher electrochemical activity as well as charge storage capacity. While the dip coated film could endure 2500 color-bleach cycles, the spin coated film could sustain only a 1000 cycles. The better cycling stability of the dip coated film which is a repercussion of a balance between optimal water content, porosity and grain size hints at its potential for electrochromic window applications

  18. Electrochemical incineration of dimethyl phthalate by anodic oxidation with boron-doped diamond electrode

    Institute of Scientific and Technical Information of China (English)

    HOU Yining; QU Jiuhui; ZHAO Xu; LIU Huijuan

    2009-01-01

    The anodic oxidation of aqueous solutions containing dimethyl phthalate (DMP) up to 125 mg/L with sodium sulfate (Na2SO4) as supporting electrolyte within the pH range 2.0-10.0 was studied using a one-compartment batch reactor employing a boron-doped diamond (BDD) as anode. Electrolyses were carried out at constant current density (1.5-4.5 mA/cm2). Complete mineralization was always achieved owing to the great concentration of hydroxyl radical (·OH) generated at the BDD surface. The effect of pH, apparent current density and initial DMP concentration on the degradation rate of DMP, the specific charge required for its total mineralization and mineralization current efficiency was investigated systematically. The mineralization rate of DMP was found to be pH-independent and to increase with increasing applied current density. Results indicated that this electrochemical process was subjected, at least partially, to the mass transfer of organics onto the BDD surface. Kinetic analysis of the temporal change of DMP concentration during electrolysis determined by High Performance Liquid Chromatography (HPLC) revealed that DMP decay under all tested conditions followed a pseudo first-order reaction. Aromatic intermediates and generated carboxylic acids were identified by Gas Chromatography-Mass Spectrometry (GC-MS) and a general pathway for the electrochemical incineration of DMP on BDD was proposed.

  19. Electrochemical Synthesis of Mesoporous CoPt Nanowires for Methanol Oxidation

    Directory of Open Access Journals (Sweden)

    Albert Serrà

    2014-03-01

    Full Text Available A new electrochemical method to synthesize mesoporous nanowires of alloys has been developed. Electrochemical deposition in ionic liquid-in-water (IL/W microemulsion has been successful to grow mesoporous CoPt nanowires in the interior of polycarbonate membranes. The viscosity of the medium was high, but it did not avoid the entrance of the microemulsion in the interior of the membrane’s channels. The structure of the IL/W microemulsions, with droplets of ionic liquid (4 nm average diameter dispersed in CoPt aqueous solution, defined the structure of the nanowires, with pores of a few nanometers, because CoPt alloy deposited only from the aqueous component of the microemulsion. The electrodeposition in IL/W microemulsion allows obtaining mesoporous structures in which the small pores must correspond to the size of the droplets of the electrolytic aqueous component of the microemulsion. The IL main phase is like a template for the confined electrodeposition. The comparison of the electrocatalytic behaviours towards methanol oxidation of mesoporous and compact CoPt nanowires of the same composition, demonstrated the porosity of the material. For the same material mass, the CoPt mesoporous nanowires present a surface area 16 times greater than compact ones, and comparable to that observed for commercial carbon-supported platinum nanoparticles.

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

    Science.gov (United States)

    Yang, Kyungwhan; Cho, Kyoungah; Kim, Sangsig

    2018-06-01

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

  1. Defect physics vis-à-vis electrochemical performance in layered mixed-metal oxide cathode materials

    Science.gov (United States)

    Hoang, Khang; Johannes, Michelle

    Layered mixed-metal oxides with different compositions of (Ni,Co,Mn) [NCM] or (Ni,Co,Al) [NCA] have been used in commercial lithium-ion batteries. Yet their defect physics and chemistry is still not well understood, despite having important implications for the electrochemical performance. In this presentation, we report a hybrid density functional study of intrinsic point defects in the compositions LiNi1/3Co1/3Mn1/3O2 (NCM1/3) and LiNi1/3Co1/3Al1/3O2 (NCA1/3) which can also be regarded as model compounds for NCM and NCA. We will discuss defect landscapes in NCM1/3 and NCA1/3 under relevant synthesis conditions with a focus on the formation of metal antisite defects and its implications on the electrochemical properties and ultimately the design of NCM and NCA cathode materials.

  2. Electrochemical supercapacitors of cobalt hydroxide nanoplates grown on conducting cadmium oxide base-electrodes

    Directory of Open Access Journals (Sweden)

    Kailas K. Tehare

    2017-05-01

    Full Text Available Dopant-free and cost-effective sprayed cadmium oxide (CdO conducting base-electrodes, obtained at different concentrations (0.5, 1 and 1.5 M, characterized for their structures, morphologies and conductivities by using X-ray diffraction, scanning electron microscopy and electrical conductivity measurements, respectively, are employed as base-electrodes for growing cobalt hydroxide (Co(OH2 nanoplates using a simple electrodeposition method which further are envisaged for electrochemical supercapacitor application. Polycrystalline nature and mushroom-like plane-views are confirmed from the structure and morphology analyses. Both CdO and CdO–Co(OH2 electrodes reveal specific capacitances as high as 312 F g−1 and 1119 F g−1, respectively, in 0.1 M KOH electrolyte at 10 mV s−1 sweep rate. Optimized Co(OH2–CdO configuration electrode demonstrates energy density of 98.83 W h kg−1 and power density of 0.75 kW kg−1. In order to investigate the charge transfer kinematics electrochemical impedance measurements are carried out and explored.

  3. In-situ polymerization of polyaniline on the surface of graphene oxide for high electrochemical capacitance

    International Nuclear Information System (INIS)

    Li, Xinlu; Zhong, Qineng; Zhang, Xinlin; Li, Tongtao; Huang, Jiamu

    2015-01-01

    Conducting polymer polyaniline (PANI) was in-situ polymerized on the surface of graphene oxide (GO) to form PANI encapsulating GO nanocomposites. The morphology and microstructure were examined by scanning electron microscopy, X-ray diffraction and N 2 absorption/desorption analysis. Electrochemical properties were tested by cyclic voltammetry, galvanostatic charge/discharge cycles and electrochemical impedance spectroscopy. Experimental results showed that ethanol assisted the dispersion of GO in water and facilitated the diffusion of polymer monomers on GO. GO as a support material can provide sufficient reaction sites for the deposition of aniline to form the film-like GO/PANI composites. Capacitive performance illustrated that the in-situ polymerization of PANI on GO was effective in improving the specific capacitance and cycling stability. - Highlights: • GO/PANI nanocomposites were achieved by in-situ polymerization. • PANI was uniformly coated on the surface of GO with addition of ethanol. • GO/PANI show high specific capacitance and cycling stability

  4. Synthesis of cadmium oxide doped ZnO nanostructures using electrochemical deposition

    International Nuclear Information System (INIS)

    Singh, Trilok; Pandya, D.K.; Singh, R.

    2011-01-01

    Research highlights: → Ternary ZnCdO alloy semiconductor nanostructures were grown using electrochemical deposition. → X-ray diffraction measurements showed that the nanostructures were of wurtzite structure and possessed a compressive stress along the c-axis direction. → The cut-off wavelength shifted from blue to red on account of the Cd incorporation in the ZnO and the average transmittance decreased by ∼31%. → The bandgap tuning for 4-16 at% Cd in the initial solution was achieved in the range of 3.08-3.32 eV (up to 0.24 eV). - Abstract: Ternary ZnCdO alloy semiconductor nanostructures were grown using electrochemical deposition. Crystalline nanostructures/nanorods with cadmium concentration ranging from 4 to 16 at% in the initial solution were electrodeposited on tin doped indium oxide (ITO) conducting glass substrates at a constant cathodic potential -0.9 V and subsequently annealed in air at 300 deg. C. X-ray diffraction measurements showed that the nanostructures were of wurtzite structure and possessed a compressive stress along the c-axis direction. The elemental composition of nanostructures was confirmed by energy dispersive spectroscopy (EDS). ZnO nanostructures were found to be highly transparent and had an average transmittance of 85% in the visible range of the spectrum. After the incorporation of Cd content into ZnO the average transmittance decreased and the bandgap tuning was also achieved.

  5. Electropolishing of AISI-304 stainless steel using an oxidizing solution originally used for electrochemical coloration

    International Nuclear Information System (INIS)

    Andrade, Leonardo S.; Xavier, Sandro C.; Rocha-Filho, Romeu C.; Bocchi, Nerilso; Biaggio, Sonia R.

    2005-01-01

    Chemical polishing or electropolishing, instead of mechanical polishing, are recommended for the attainment of metallic surface polishes without the introduction of contaminants or tensions in the surface layers of the metal. The fundamental difference between the chemical and electrochemical polishing processes is that in the latter anodic currents/potentials are used to help in the dissolution and passivation of the metal. In this paper, the use of an oxidizing electrolytic solution (2.5 mol L -1 CrO 3 + 5.0 mol L -1 H 2 SO 4 ) originally employed in electrochemical coloration processes is reported for the electropolishing of AISI-314 stainless steel. Parameters involved in this electropolishing process, such as temperature, current density and time, were optimized so as to attain the best possible results evaluated by the obtained surface brightness measured by reflectance spectra. Surface analyses by scanning electron microscopy allowed a clear correlation between obtained brightness and surface smoothing. The best conditions obtained for the electropolishing process are: temperature of 45 deg. C, electrolysis time of 10 min and current density of around 25 A dm -2 . It should be pointed out that an electropolishing process signature (periodic oscillations of the cell potential) was established; this may be an important tool for optimizing and monitoring electropolishing processes

  6. Electrochemical properties and electrocatalytic activity of conducting polymer/copper nanoparticles supported on reduced graphene oxide composite

    Science.gov (United States)

    Ehsani, Ali; Jaleh, Babak; Nasrollahzadeh, Mahmoud

    2014-07-01

    Reduced graphene oxide (rGO) was used to support Cu nanoparticles. As electro-active electrodes for supercapacitors composites of reduced graphene oxide/Cu nanoparticles (rGO/CuNPs) and polytyramine (PT) with good uniformity are prepared by electropolymerization. Composite of rGO/CuNPs-PT was synthesized by cyclic voltammetry (CV) methods and electrochemical properties of film were investigated by using electrochemical techniques. The results show that, the rGO/CuNPs-PT/G has better capacitance performance. This is mainly because of the really large surface area and the better electronic and ionic conductivity of rGO/CuNPs-PT/G, which lead to greater double-layer capacitance and faradic pseudo capacitance. Modified graphite electrodes (rGO/CuNPs-PT/G) were examined for their redox process and electrocatalytic activities towards the oxidation of methanol in alkaline solutions. The methods of cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS) were employed. In comparison with a Cu-PT/G (Graphite), rGO/CuNPs-PT/G modified electrode shows a significantly higher response for methanol oxidation. A mechanism based on the electro-chemical generation of Cu(III) active sites and their subsequent consumptions by methanol have been discussed.

  7. The influence of oxide on the electrochemical processes in K2NbF7-NaCl-KCl melts

    DEFF Research Database (Denmark)

    Lantelme, F.; Berghoute, Y.; Barner, Jens H. Von

    1995-01-01

    Transient electrochemical techniques showed that in NaCl-KCl melts the reduction of K2NbF7 occurs through atwo-step reaction Nb(V) --> Nb(IV) --> Nb. When oxide ions were introduced, cyclic voltammetry indicated that the wavescorresponding to reduction of the complex NbF72- progressively...

  8. Degradation of Acetaminophen and Its Transformation Products in Aqueous Solutions by Using an Electrochemical Oxidation Cell with Stainless Steel Electrodes

    Directory of Open Access Journals (Sweden)

    Miguel Ángel López Zavala

    2016-09-01

    Full Text Available In this study, a novel electrochemical oxidation cell using stainless steel electrodes was found to be effective in oxidizing acetaminophen and its transformation products in short reaction times. Aqueous solutions of 10 mg/L-acetaminophen were prepared at pH 3, 5, 7, and 9. These solutions were electrochemically treated at direct current (DC densities of 5.7 mA/cm2, 7.6 mA/cm2, and 9.5 mA/cm2. The pharmaceutical and its intermediates/oxidation products were determined by using high pressure liquid chromatography (HPLC. The results showed that electrochemical oxidation processes occurred in the cell. Acetaminophen degradation rate constants increased proportionally with the increase of current intensity. High current densities accelerated the degradation of acetaminophen; however, this effect diminished remarkably at pH values greater than 5. At pH 3 and 9.5 mA/cm2, the fastest degradation of acetaminophen and its intermediates/oxidation products was achieved. To minimize the wear down of the electrodes, a current density ramp is recommended, first applying 9.5 mA/cm2 during 2.5 min or 7.6 mA/cm2 during 7.5 min and then continuing the electrochemical oxidation process at 5.7 mA/cm2. This strategy will hasten the acetaminophen oxidation, extend the electrode’s life, and shorten the reaction time needed to degrade the pharmaceutical and its intermediates/oxidation products. DC densities up to 9.5 mA/cm2 can be supplied by photovoltaic cells.

  9. Recent Advances in Metal Chalcogenides (MX; X = S, Se) Nanostructures for Electrochemical Supercapacitor Applications: A Brief Review

    Science.gov (United States)

    Theerthagiri, Jayaraman; Durai, Govindarajan; Rana, Abu ul Hassan Sarwar; Sangeetha, Kirubanandam; Kuppusami, Parasuraman; Kim, Hyun-Seok

    2018-01-01

    Supercapacitors (SCs) have received a great deal of attention and play an important role for future self-powered devices, mainly owing to their higher power density. Among all types of electrical energy storage devices, electrochemical supercapacitors are considered to be the most promising because of their superior performance characteristics, including short charging time, high power density, safety, easy fabrication procedures, and long operational life. An SC consists of two foremost components, namely electrode materials, and electrolyte. The selection of appropriate electrode materials with rational nanostructured designs has resulted in improved electrochemical properties for high performance and has reduced the cost of SCs. In this review, we mainly spotlight the non-metallic oxide, especially metal chalcogenides (MX; X = S, Se) based nanostructured electrode materials for electrochemical SCs. Different non-metallic oxide materials are highlighted in various categories, such as transition metal sulfides and selenides materials. Finally, the designing strategy and future improvements on metal chalcogenide materials for the application of electrochemical SCs are also discussed. PMID:29671823

  10. Designing advanced materials by environmental friendly plasma electrolytic oxidation

    International Nuclear Information System (INIS)

    Toader, I.; Valeca, M.; Rusu, O.; Coaca, E.; Marin, A.

    2016-01-01

    In the CANDU-PHWR nuclear reactors, Zr-2.5Nb coated with a black adherent oxide film of 1 to 2 μm in thickness is currently used for the manufacture of pressure tubes. The black oxide thin film has corrosion protective properties. However, it can be damaged during the regular refueling process, thus causing hydrogen/oxygen ingression. Therefore, an enhanced wear and corrosion resistance coating is needed. Plasma electrolytic oxidation (PEO) is an anodic electrochemical treatment, both cost-effective and environmentally friendly, widely used in the formation of a protective oxide film on the metal surface to enhance wear and corrosion resistance as well as prolonging component lifetime. The state of the art reveals that PEO method is suitable for improving the wear resistance of Zr-2.5Nb alloy. Few studies are performed in this field and thus, it is necessary to conduct a more detailed insight study on the processing parameters for PEO treatment. By understanding the influence of process parameters, such as electrolyte temperature and electrolyte composition, we can find the way to obtain a coating with improved mechanical and corrosion properties on zirconium alloys. (authors)

  11. Controlled synthesis and electrochemical properties of vanadium oxides with different nanostructures

    International Nuclear Information System (INIS)

    Zhang, Yifu; Zhou, Min; Huang, Chi; Chen, Chongxue; Cao, Yuliang; Fan, Meijuan; Li, Houbin; Liu, Xinghai; Xie, Guangyong

    2012-01-01

    Vanadium oxides (V 3 O 7 .H 2 O and VO 2 ) with different morphologies have been selectively synthesized by a facile hydrothermal approach using glucose as the reducing and structure-directing reagent. The as-obtained V 3 O 7 .H 2 O nanobelts have a length up to several tens of micrometers, width of about 60-150 nm and thickness of about 5-10 nm, while the as-prepared VO 2 (B) nanobelts have a length of about 1.0- 7 μm, width, 80-140 nm and thickness, 2-8 nm. It was found that the quantity of glucose, the reaction temperature and the reaction time had significant influence on the compositions and morphologies of final products. Vanadium oxides with different morphologies were easily synthesized by controlling the concentration of glucose. The formation mechanism was also briefly discussed, indicating that glucose played different roles in synthesizing various vanadium oxides. The phase transition from VO 2 (B) to VO 2 (M) were investigated and the phase transition temperature of the VO 2 (M) appeared at around 68 deg C. Furthermore, the electrochemical properties of V 3 O 7 .H 2 O nanobelts, VO 2 (B) nanobelts and VO 2 (B) nanosheets were investigated and they exhibited a high initial discharge capacity of 296, 247 and 227 mAh/g, respectively. (author)

  12. Sequential electrochemical oxidation and site-selective growth of nanoparticles onto AFM probes.

    Science.gov (United States)

    Wang, Haitao; Tian, Tian; Zhang, Yong; Pan, Zhiqiang; Wang, Yong; Xiao, Zhongdang

    2008-08-19

    In this work, we reported an approach for the site-selective growth of nanoparticle onto the tip apex of an atomic force microscopy (AFM) probe. The silicon AFM probe was first coated with a self-assembled monolayer (SAM) of octadecyltrichlorosilane (OTS) through a chemical vapor deposition (CVD) method. Subsequently, COOH groups were selectively generated at the tip apex of silicon AFM probes by applying an appropriate bias voltage between the tip and a flat gold electrode. The transformation of methyl to carboxylic groups at the tip apex of the AFM probe was investigated through measuring the capillary force before and after electrochemical oxidation. To prepare the nanoparticle terminated AFM probe, the oxidized AFM probe was then immersed in an aqueous solution containing positive metal ions, for example, Ag+, to bind positive metal ions to the oxidized area (COOH terminated area), followed by chemical reduction with aqueous NaBH 4 and further development (if desired) to give a metal nanoparticle-modified AFM probe. The formation of a metal nanoparticle at the tip apex of the AFM probe was confirmed by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDXA).

  13. Electrochemical oxidation of pulp and paper making wastewater assisted by transition metal modified kaolin

    International Nuclear Information System (INIS)

    Wang Bo; Gu Lin; Ma Hongzhu

    2007-01-01

    The electrochemical oxidation of pulp and paper making wastewater assisted by transition metal (Co, Cu) modified kaolin in a 200 ml electrolytic batch reactor with graphite plate as electrodes was investigated. H 2 O 2 , which produced on the surface of porous graphite cathode, would react with the catalysts to form strong oxidant (hydroxyl radicals) that can in turn destruct the pollutants adsorbed on the surface of kaolin. The transition metal (Co, Cu) modified kaolin was also characterized by XRD and SEM before and after the modification and the results showed that the transition metals were completely supported on kaolin and formed a porous structure with big BET surface. The mechanism was proposed on the basis of XPS analysis of the catalyst after the degradation process. Series of experiments were also done to prove the synergetic effect of the combined oxidation system and to find out the optimal operating parameters such as initial pH, current density and amount of catalyst. From the results it can be founded that when the initial pH was at 3, current density was 30 mA cm -2 ; catalyst dose was 30 g dm -3 , COD (chemical oxygen demand) removal could reach up to 96.8% in 73 min

  14. Graphene-zinc oxide (G-ZnO nanocomposite for electrochemical supercapacitor applications

    Directory of Open Access Journals (Sweden)

    Murugan Saranya

    2016-12-01

    Full Text Available Graphene-ZnO nanocomposites (G-ZnO were prepared by a facile solvothermal approach. Well, crystalline ZnO nanoparticles with size in the range of 30–70 nm are uniformly deposited on the graphene sheets, as evidenced by different techniques. The electrochemical properties of the prepared nanocomposites were examined by measuring the specific capacitance in 6 M KOH solution using cyclic voltammetry and galvanostatic charge–discharge techniques. G-ZnO nanocomposites showed a good capacitive behavior with a specific capacitance of 122.4 F/g as compared to graphene oxide (2.13 F/g and rGO (102.5 F/g at 5 mV/s scan rate. Results demonstrated that such hybrid materials are promising electrode materials for high-performance supercapacitor applications.

  15. Electrochemical oxidation of sulfites by DWCNTs, MWCNTs, higher fullerenes and manganese

    Science.gov (United States)

    Uzun, Dzhamal; Pchelarov, George; Dimitrov, Ognian; Vassilev, Sasho; Obretenov, Willi; Petrov, Konstantin

    2018-03-01

    Different electrocatalysts were tested for oxidation of sulfites to sulfates, namely, manganese thin films deposited on fullerenes and carbon nanotubes. The results presented clearly show that electrodes containing HFs (higher fullerenes), DWCNTs (double-wall carbon nanotubes) and manganese acetate are effective catalysts in S/O2 fuel cells. HFs and DWCNTs have high catalytic activity and can be employed as standalone catalysts. Manganese was deposited on DWCNTs, HFs and fullerenes C60/C70 by a thermal process. The electrocatalysts were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The electrochemical testing was carried out by plotting the E/V polarization curve. The polarization curves of the electrodes composed of pristine DWCNTs showed the lowest overpotentials.

  16. Clean and Green Synthesis of New Benzothiazole Derivatives via Electrochemical Oxidation of Catechol Derivatives

    Directory of Open Access Journals (Sweden)

    Mansour Arab Chamjangali

    2016-06-01

    Full Text Available Electrochemical oxidation of the catechols 1a and 1b is studied in the presence of 6-methyl-2-thouracil (3b and 6-propyl-2-thiouracil (3a as nucleophiles in a phosphate buffer (0.15 mol L−1, pH = 6.8/DMF (95:5 solution using cyclic voltammetry and controlled-potential coulometry. The results obtained indicate that the quinones derived from the catechols participate in 1,4-Michael-addition reactions with the nucleophiles to form the corresponding new benzothiazole compounds. In this work, we derive a variety of products with good yields using controlled potential at graphite electrodes in an undivided cell. This work is licensed under a Creative Commons Attribution 4.0 International License.

  17. Electrochemical synthesis of gold nanoparticles onto indium tin oxide glass and application in biosensors

    Energy Technology Data Exchange (ETDEWEB)

    Hu Yanling; Song Yan; Wang Yuan; Di Junwei, E-mail: djw@suda.edu.cn

    2011-07-29

    A simple one-step method for the electrochemical deposition of gold nanoparticles (GNPs) onto bare indium tin oxide film coated glass substrate without any template or surfactant was investigated. The effect of electrolysis conditions such as potential range, temperature, concentration and deposition cycles were examined. The connectivity of GNPs was analyzed by UV-Vis absorption spectroscopy and scanning electron microscopy. The nanoparticles were found to connect in pairs or to coalesce in larger numbers. The twin GNPs display a transverse and a longitudinal localized surface plasmon resonance (LSPR) band, which is similar to that of gold nanorods. The presence of longitudinal LSPR band correlates with high refractive index sensitivity. Conjugation of the twin-linked GNPs with albumin bovine serum-biotin was employed for the detection of streptavidin as a model based on the specific binding affinity in biotin/streptavidin pairs. The spectrophotometric sensor showed concentration-dependent binding for streptavidin.

  18. Electrochemically reduced graphene oxide-modified screen-printed carbon electrodes for a simple and highly sensitive electrochemical detection of synthetic colorants in beverages.

    Science.gov (United States)

    Jampasa, Sakda; Siangproh, Weena; Duangmal, Kiattisak; Chailapakul, Orawon

    2016-11-01

    A simple and highly sensitive electrochemical sensor based on an electrochemically reduced graphene oxide-modified screen-printed carbon electrode (ERGO-SPCE) for the simultaneous determination of sunset yellow (SY) and tartrazine (TZ) was proposed. An ERGO film was coated onto the electrode surface using a cyclic voltammetric method and then characterized by scanning electron microscopy (SEM). In 0.1M phosphate buffer at a pH of 6, the two oxidation peaks of SY and TZ appeared separately at 0.41 and 0.70V, respectively. Surprisingly, the electrochemical response remarkably increased approximately 90- and 20-fold for SY and TZ, respectively, using the modified electrode in comparison to the unmodified electrode. The calibration curves exhibited linear ranges from 0.01 to 20.0µM for SY and from 0.02 to 20.0µM for TZ. The limits of detection were found to be 0.50 and 4.50nM (at S/N=3) for SY and TZ, respectively. Furthermore, this detection platform provided very high selectivity for the measurement of both colorants. This electrochemical sensor was successfully applied to determine the amount of SY and TZ in commercial beverages. Comparison of the results obtained from this proposed method to those obtained by an in-house standard technique proved that this developed method has good agreement in terms of accuracy for practical applications. This sensor offers an inexpensive, rapid and sensitive determination. The proposed system is therefore suitable for routine analysis and should be an alternative method for the analysis of food colorants. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Electrocatalytic oxidative determination of reserpine at electrochemically functionalized single walled carbon nanotube with polyaniline

    International Nuclear Information System (INIS)

    Dar, Riyaz Ahmad; Naikoo, Gowhar Ahmad; Pitre, Krishna Sadashive

    2013-01-01

    Graphical abstract: Electrode oxidation mechanism of reserpine at PANI modified-SWCNT/CPE. -- Highlights: • Electropolymerization of polyaniline at SWCNT/CPE. • CV, EIS, CC SEM techniques were used for characterization of electrode. • Electrode showed electrocatalytic activity towards anodic oxidation of reserpine. • Oxidation process as irreversible and adsorption-controlled. • Reserpine in bark of Rauwolfia serpentina and in its pharmaceutical formulations. -- Abstract: In the present work a polyaniline film was successfully deposited by electropolymerization on single walled carbon nanotube paste electrode. The electrode was characterized using cyclic voltammetry, electrochemical impedance spectroscopy, chronocoulometry and scanning electron microscopy. The modified electrode showed electrocatalytic behaviour towards the anodic oxidation of reserpine. The adsorptive stripping voltammetric behaviour of reserpine at polyaniline film modified single walled carbon nanotube paste electrode (modified-SWCNTPE) was investigated and validated in pharmaceuticals and biological fluids by cyclic voltammetry (CV) and adsorptive stripping differential pulse voltammetry (AdSDPV) in 0.02 M phosphate buffer in the pH range of 2.5–8.5. Cyclic voltammetry has shown that the oxidation process is irreversible over the pH range studied and exhibited an adsorption-controlled behaviour. Further, the overall electrode process is mainly diffusion controlled with adsorption effects. The proposed more sensitive AdSDPV method allow quantitation over the range 0.085 μg mL −1 to 0.87 μg mL −1 with the detection limit of 0.407 ng mL −1 and has been successfully used to determine reserpine in bark of Rauwolfia serpentina and in its pharmaceutical formulations

  20. β-Cyclodextrin polymer functionalized reduced-graphene oxide: Application for electrochemical determination imidacloprid

    International Nuclear Information System (INIS)

    Chen, Ming; Meng, Yang; Zhang, Wang; Zhou, Jun; Xie, Ju; Diao, Guowang

    2013-01-01

    Highlights: • β-CDP/rGO nanocomposites were prepared by a facile strategy. • β-CDP/rGO nanocomposites displayed the excellent water-dispersity and stability. • β-CDP/rGO exhibited high supramolecular recognition and enrichment capability. • β-CDP/rGO electrode showed excellent electrochemical performance for IDP. -- Abstract: Reduced-graphene oxide (rGO) modified with water-soluble β-cyclodextrin polymer (β-CDP) were successfully prepared by using a simple wet chemical strategy. The obtained β-CDP/rGO nanocomposites were characterized by Fourier transform infrared spectroscopy (FTIR), static contact angle measurement, thermogravimetric analysis (TGA), scanning electron microscope (SEM) and electrochemical impedance spectroscopy (EIS), which confirmed that β-CDP molecules had been effectively loaded onto the surface of rGO. β-CDP/rGO nanocomposites displayed the excellent water-dispersity and stability. More significantly, cyclic voltammetry and differential pulse voltammetry measurement showed that the β-CDP/rGO could exhibit high supramolecular recognition and enrichment capability, and consequently display excellent electrochemical response toward a pesticide-imidacloprid (IDP). As compared with various modified electrodes, β-CDP/rGO modified glassy carbon electrode exhibited an excellent electrochemical performance for IDP. Based on the cyclic voltammograms (CV) of different concentration of IDP at pH 6.8, the detection line range of IDP is 1 × 10 −6 to 1.5 × 10 −4 mol L −1 IDP and the detection limit is 1 × 10 −7 mol L −1 . Differential pulse voltammetry (DPV) measurement at β-CDP/rGO/GCE modified electrode revealed that the reduction peak current increased linearly with the concentration of IDP in linear range of 5 × 10 −8 to 1.5 × 10 −5 mol L −1 and 2 × 10 −5 to 1.5 × 10 −4 mol L −1 with detection limit of 2 × 10 −8 mol L −1 at a signal-to-noise ratio of 3

  1. Mediated electrochemical oxidation as an alternative to incineration for mixed wastes

    International Nuclear Information System (INIS)

    Chiba, Z.; Schumacher, B.; Lewis, P.; Murguia, L.

    1995-02-01

    Mediated Electrochemical Oxidation (MEO) is an aqueous process which oxidizes organics electrochemically at low temperatures and ambient pressures. The process can be used to treat mixed wastes containing hazardous organics by destroying the organic components of the wastes. The radioactive components of the wastes are dissolved in the electrolyte where they can be recovered if desired, or immobilized for disposal. The process of destroying organics is accomplished via a mediator, which is in the form of metallic ions in solution. At Lawrence Livermore National Laboratory (LLNL) we have worked with worked with several mediators, including silver, cobalt and cerium. We have tested mediators in nitric as well as sulfuric acids. We have recently completed extensive experimental studies on cobalt-sulfuric acid and silver-nitric acid systems for destroying the major organic components of Rocky Flats Plant combustible mixed wastes. Organics tested were: Trimsol (a cutting oil), cellulose (including paper and cloth), rubber (latex), plastics (Tyvek, polyethylene and polyvinyl chloride) and biomass (bacteria). The process was capable of destroying almost all of the organics tested, attaining high destruction efficiencies at reasonable coulombic efficiencies. The only exception was polyvinyl chloride, which was destroyed very slowly resulting in poor coulombic efficiencies. Besides the process development work mentioned above, we are working on the design of a pilot-plant scale integrated system to be installed in the Mixed Waste Management Facility (MWMF) at LLNL. The system will also be completely integrated with upstream and downstream processes (for example, feed preparation, off-gas and water treatment, and final forms encapsulation). The conceptual design for the NEO-MWMF system has been completed and preliminary design work has been initiated. Demonstration of the process with low-level mixed wastes is expected to commence in 1998

  2. Colour and organic removal of biologically treated coffee curing wastewater by electrochemical oxidation method.

    Science.gov (United States)

    Bejankiwar, Rajesh S; Lokesh, K S; Gowda, T P Halappa

    2003-05-01

    The treatment of biologically treated wastewater of coffee-curing industry by the electrochemical oxidation using steel anode was investigated. Bench-scale experiments were conducted for activated sludge process on raw wastewater and the treated effluents were further treated by electrochemical oxidation method for its colour and organic content removal. The efficiency of the process was determined in terms of removal percentage of COD, BOD and colour during the course of reaction. Several operating parameters like time, pH and current density were examined to ascertain their effects on the treatment efficiency. Steel anode was found to be effective for the COD and colour removal with anode efficiency of 0.118 kgCOD x h(-1) x A(-1) x m(-2) and energy consumption 20.61 kWh x kg(-1) of COD at pH 9. The decrease in pH from 9 to 3 found to increase the anode efficiency from 0.118 kgCOD x h(-1) x A(-1) x m(-2) to 0.144 kWh x kg(-1) of COD while decrease the energy consumption from 20.61 kWh x kg(-1) of COD to 12.86 kWh x kg(-1) of COD. The pH of 5 was considered an ideal from the present treatment process as it avoids the addition of chemicals for neutralization of treated effluents and also economical with respect to energy consumption. An empirical relation developed for relationship between applied current density and COD removal efficiency showed strong predictive capability with coefficient of determination of 96.5%.

  3. Label-free electrochemical immunosensor based on cerium oxide nanowires for Vibrio cholerae O1 detection

    International Nuclear Information System (INIS)

    Tam, Phuong Dinh; Thang, Cao Xuan

    2016-01-01

    This paper developed a label-free immunosensor based on cerium oxide nanowire for Vibrio cholerae O1 detection application. The CeO 2 nanowires were synthesized by hydrothermal reaction. The immobilization of Anti-V. cholerae O1 onto CeO 2 nanowire-deposited sensor was performed via an amino ester, which was created by using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, and sulfo-N-hydroxysuccinimide. The electrochemical responses of the immunosensor were studied by electrochemical impedance spectroscopy with [Fe (CN) 6 ] 3−/4− as redox probe. A linear response in electron transfer resistance for cell of V. cholerae O1 concentration was found in the range of 1.0 × 10 2 CFU/mL to 1.0 × 10 4 CFU/mL. The detection limit of the immunosensor was 1.0 × 10 2 CFU/mL. The immunosensor sensitivity was 56.82 Ω/CFU·mL −1 . Furthermore, the parameters affecting immunosensor response were also investigated, as follows: pH value, immunoreaction time, incubation temperature, and anti-V. cholerae O1 concentration. - Highlights: • A label-free immunosensor based on cerium oxide nanowire for Vibrio cholerae O1 detection application was developed. • A linear response was found in the range of 1.0 × 10 2 CFU/mL to 1.0 × 10 4 CFU/mL. • The detection limit of the immunosensor was 1.0 × 10 2 CFU/mL. • The immunosensor sensitivity was 56.82 Ω/CFU.mL −1 .

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

    Energy Technology Data Exchange (ETDEWEB)

    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 Ω 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.

  5. Label-free electrochemical immunosensor based on cerium oxide nanowires for Vibrio cholerae O1 detection

    Energy Technology Data Exchange (ETDEWEB)

    Tam, Phuong Dinh, E-mail: phuongdinhtam@gmail.com; Thang, Cao Xuan, E-mail: thang.caoxuan@hust.edu.vn

    2016-01-01

    This paper developed a label-free immunosensor based on cerium oxide nanowire for Vibrio cholerae O1 detection application. The CeO{sub 2} nanowires were synthesized by hydrothermal reaction. The immobilization of Anti-V. cholerae O1 onto CeO{sub 2} nanowire-deposited sensor was performed via an amino ester, which was created by using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide, and sulfo-N-hydroxysuccinimide. The electrochemical responses of the immunosensor were studied by electrochemical impedance spectroscopy with [Fe (CN) {sub 6}] {sup 3−/4−} as redox probe. A linear response in electron transfer resistance for cell of V. cholerae O1 concentration was found in the range of 1.0 × 10{sup 2} CFU/mL to 1.0 × 10{sup 4} CFU/mL. The detection limit of the immunosensor was 1.0 × 10{sup 2} CFU/mL. The immunosensor sensitivity was 56.82 Ω/CFU·mL{sup −1}. Furthermore, the parameters affecting immunosensor response were also investigated, as follows: pH value, immunoreaction time, incubation temperature, and anti-V. cholerae O1 concentration. - Highlights: • A label-free immunosensor based on cerium oxide nanowire for Vibrio cholerae O1 detection application was developed. • A linear response was found in the range of 1.0 × 10{sup 2} CFU/mL to 1.0 × 10{sup 4} CFU/mL. • The detection limit of the immunosensor was 1.0 × 10{sup 2} CFU/mL. • The immunosensor sensitivity was 56.82 Ω/CFU.mL{sup −1}.

  6. Oxidation Phenomena in Advanced High Strength Steels : Modelling and Experiment

    NARCIS (Netherlands)

    Mao, W.

    2018-01-01

    Galvanized advanced high strength steels (AHSS) will be the most competitive structural material for automotive applications in the next decade. Oxidation of AHSS during the recrystalization annealing process in a continuous galvanizing line to a large extent influences the quality of zinc coating

  7. Nanostructured Metal Oxide Coatings for Electrochemical Energy Conversion and Storage Electrodes

    Science.gov (United States)

    Cordova, Isvar Abraxas

    The realization of an energy future based on safe, clean, sustainable, and economically viable technologies is one of the grand challenges facing modern society. Electrochemical energy technologies underpin the potential success of this effort to divert energy sources away from fossil fuels, whether one considers alternative energy conversion strategies through photoelectrochemical (PEC) production of chemical fuels or fuel cells run with sustainable hydrogen, or energy storage strategies, such as in batteries and supercapacitors. This dissertation builds on recent advances in nanomaterials design, synthesis, and characterization to develop novel electrodes that can electrochemically convert and store energy. Chapter 2 of this dissertation focuses on refining the properties of TiO2-based PEC water-splitting photoanodes used for the direct electrochemical conversion of solar energy into hydrogen fuel. The approach utilized atomic layer deposition (ALD); a growth process uniquely suited for the conformal and uniform deposition of thin films with angstrom-level thickness precision. ALD's thickness control enabled a better understanding of how the effects of nitrogen doping via NH3 annealing treatments, used to reduce TiO2's bandgap, can have a strong dependence on TiO2's thickness and crystalline quality. In addition, it was found that some of the negative effects on the PEC performance typically associated with N-doped TiO2 could be mitigated if the NH 3-annealing was directly preceded by an air-annealing step, especially for ultrathin (i.e., transparent electrode based on a network of solution-processed Cu/Ni cores/shell nanowires (NWs) were activated by electrochemically converting the Ni metal shell into Ni(OH)2. Furthermore, an adjustment of the molar percentage of Ni plated onto the Cu NWs was found to result in a tradeoff between capacitance, transmittance, and stability of the resulting nickel hydroxide-based electrode. The nominal area capacitance and power

  8. Electrochemical degradation of Novacron Yellow C-RG using boron-doped diamond and platinum anodes: Direct and Indirect oxidation

    International Nuclear Information System (INIS)

    Rocha, J.H. Bezerra; Gomes, M.M. Soares; Santos, E. Vieira dos; Moura, E.C. Martins de; Silva, D. Ribeiro da; Quiroz, M.A.; Martínez-Huitle, C.A.

    2014-01-01

    Graphical abstract: - Highlights: • Nature of electrode material decides the electrocatalytic mechanism followed. • Electrogenerated strong oxidants on BDD surface improve the color and organic load removal. • Chlorine active species act in solution cage oxidizing organic matter. - Abstract: The present study discusses the electrochemical degradation process of a textile dye, Novacron Yellow C-RG (NY), dissolved in synthetic wastewaters, via direct and indirect oxidation. Experiments were conducted using boron-doped diamond (BDD) and platinum supported on Ti (Pt/Ti) electrodes in the absence and presence of NaCl in the solution. The direct process for removing color is relatively similar for both anodes, while the electrochemical degradation is significantly accelerated by the presence of halogen salt in the solution. Interestingly, it does not depend on applied current density, but rather on NaCl concentration. Therefore, the electrochemical processes (direct/indirect) favor specific oxidation pathways depending on electrocatalytic material. Whereas, the Pt/Ti anode favors preferentially color removal by direct and indirect oxidation (100% of color removal) due to the fragmentation of the azo dye group; BDD electrode favors color and organic load removals in both processes (95% and up to 87%, respectively), due to the rupture of dye in different parts of its chemical structure. Parameters of removal efficiency and energy consumption for the electrochemical process were estimated. Finally, an explanation has been attempted for the role of halide, in relation with the oxygen evolution reaction, concomitant with the electrochemical incineration as well as electrocatalytic mechanisms, for each one of the electrodes used

  9. Electrochemical impedance spectroscopy investigation on indium tin oxide films under cathodic polarization in NaOH solution

    International Nuclear Information System (INIS)

    Gao, Wenjiao; Cao, Si; Yang, Yanze; Wang, Hao; Li, Jin; Jiang, Yiming

    2012-01-01

    The electrochemical corrosion behaviors of indium tin oxide (ITO) films under the cathodic polarization in 0.1 M NaOH solution were investigated by electrochemical impedance spectroscopy. The as-received and the cathodically polarized ITO films were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction for morphological, compositional and structural studies. The results showed that ITO films underwent a corrosion process during the cathodic polarization and the main component of the corrosion products was body-centered cubic indium. The electrochemical impedance parameters were related to the effect of the cathodic polarization on the ITO specimens. The capacitance of ITO specimens increased, while the charge transfer resistance and the inductance decreased with the increase of the polarization time. The proposed mechanism indicated that the corrosion products (metallic indium) were firstly formed during the cathodic polarization and then absorbed on the surface of the ITO film. As the surface was gradually covered by indium particles, the corrosion process was suppressed. - Highlights: ► Cathodic polarization of indium tin oxide (ITO) in 0.1 M NaOH. ► Cathodic polarization studied with electrochemical impedance spectroscopy. ► ITO underwent a corrosion attack during cathodic polarization, indium was observed. ► Electrochemical parameters of ITO were obtained using equivalent electrical circuit. ► A corrosion mechanism is proposed.

  10. Pretreatment of whole blood using hydrogen peroxide and UV irradiation. Design of the advanced oxidation process.

    Science.gov (United States)

    Bragg, Stefanie A; Armstrong, Kristie C; Xue, Zi-Ling

    2012-08-15

    A new process to pretreat blood samples has been developed. This process combines the Advanced Oxidation Process (AOP) treatment (using H(2)O(2) and UV irradiation) with acid deactivation of the enzyme catalase in blood. A four-cell reactor has been designed and built in house. The effect of pH on the AOP process has been investigated. The kinetics of the pretreatment process shows that at high C(H(2)O(2),t=0), the reaction is zeroth order with respect to C(H(2)O(2)) and first order with respect to C(blood). The rate limiting process is photon flux from the UV lamp. Degradation of whole blood has been compared with that of pure hemoglobin samples. The AOP pretreatment of the blood samples has led to the subsequent determination of chromium and zinc concentrations in the samples using electrochemical methods. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Electrochemical Characteristics of Layered Transition Metal Oxide Cathode Materials for Lithium Ion Batteries: Surface, Bulk Behavior, and Thermal Properties.

    Science.gov (United States)

    Tian, Chixia; Lin, Feng; Doeff, Marca M

    2018-01-16

    Layered lithium transition metal oxides, in particular, NMCs (LiNi x Co y Mn z O 2 ) represent a family of prominent lithium ion battery cathode materials with the potential to increase energy densities and lifetime, reduce costs, and improve safety for electric vehicles and grid storage. Our work has focused on various strategies to improve performance and to understand the limitations to these strategies, which include altering compositions, utilizing cation substitutions, and charging to higher than usual potentials in cells. Understanding the effects of these strategies on surface and bulk behavior and correlating structure-performance relationships advance our understanding of NMC materials. This also provides information relevant to the efficacy of various approaches toward ensuring reliable operation of these materials in batteries intended for demanding traction and grid storage applications. In this Account, we start by comparing NMCs to the isostructural LiCoO 2 cathode, which is widely used in consumer batteries. Effects of changing the metal content (Ni, Mn, Co) upon structure and performance of NMCs are briefly discussed. Our early work on the effects of partial substitution of Al, Fe, and Ti for Co on the electrochemical and bulk structural properties is then covered. The original aim of this work was to reduce the Co content (and thus the raw materials cost) and to determine the effect of the substitutions on the electrochemical and bulk structural properties. More recently, we have turned to the application of synchrotron and advanced microscopy techniques to understand both bulk and surface characteristics of the NMCs. Via nanoscale-to-macroscale spectroscopy and atomically resolved imaging techniques, we were able to determine that the surfaces of NMC undergo heterogeneous reconstruction from a layered structure to rock salt under a variety of conditions. Interestingly, formation of rock salt also occurs under abuse conditions. The surface

  12. Nano-scale islands of ruthenium oxide as an electrochemical sensor for iodate and periodate determination

    International Nuclear Information System (INIS)

    Chatraei, Fatemeh; Zare, Hamid R.

    2013-01-01

    In this study, a promising electrochemical sensor was fabricated by the electrodeposition of nano-scale islands of ruthenium oxide (ruthenium oxide nanoparticles, RuON) on a glassy carbon electrode (RuON–GCE). Then, the electrocatalytic oxidation of iodate and periodate was investigated on it, using cyclic voltammetry, chronoamperometry and amperometry as diagnostic techniques. The charge transfer coefficient, α, and the charge transfer rate constant, k s , for electron transfer between RuON and GCE were calculated as 0.5 ± 0.03 and 9.0 ± 0.7 s −1 respectively. A comparison of the data obtained from the electrocatalytic reduction of iodate and periodate at a bare GCE (BGCE) and RuON–GCE clearly shows that the unique electronic properties of nanoparticles definitely improve the characteristics of iodate and periodate electrocatalytic reduction. The kinetic parameters such as the electron transfer coefficient, α, and the heterogeneous electron transfer rate constant, k′, for the reduction of iodate and periodate at RuON–GCE surface were determined using cyclic voltammetry. Amperometry revealed a good linear relationship between the peak current and the concentration of iodate and periodate. The detection limits of 0.9 and 0.2 μM were calculated for iodate and periodate respectively. Highlights: ► Ruthenium oxide nanoparticles, RuON, were used for electrocatalytic reduction iodate and periodate. ► Formal potential, E 0 ′, of the surface redox couple of RuON is pH-dependent. ► The heterogeneous electron transfer rate constant values between both analytes and RuON were calculated.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    International Nuclear Information System (INIS)

    Molina, J.; Fernández, J.; Río, A.I. del; Bonastre, J.; Cases, F.

    2014-01-01

    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 −2 ) was established. The electrodes obtained were characterized in 0.5 M H 2 SO 4 solution to observe the characteristic oxidation and reduction processes of the Pt surface. A 0.5 M H 2 SO 4 /0.5 M CH 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

  15. N, P-codoped Mesoporous Carbon Supported PtCox Nanoparticles and Their Superior Electrochemical toward Methanol Oxidation

    Science.gov (United States)

    Cui, Hangjun; Li, Yueming; Liu, Shimin

    2018-03-01

    In this report, a novel strategy by using the N, P co-doped mesoporous carbon structure as catalyst support to enhance the electrochemical catalytic activity of Pt-based catalysts is proposed. The as-synthesized PtCox@N, P-doped mesoporous carbon nanocomposties have been studied as an anode catalyst toward methanol oxidation, exhibiting greatly improved electrochemical activity and stability compared with Pt@mesoporous carbon. The synergistic effects of N, P dual-doping and porous carbon structure help to achieve better electron transport at the electrode surface, which eventually leads to greatly enhanced catalytic activity compared to the pristine Pt/mesoporous carbon.…

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

    Directory of Open Access Journals (Sweden)

    Baoyan Wu

    2016-11-01

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

  17. Electrochemical oxidation of tetracycline antibiotics using a Ti/IrO2 anode for wastewater treatment of animal husbandry.

    Science.gov (United States)

    Miyata, M; Ihara, I; Yoshid, G; Toyod, K; Umetsu, K

    2011-01-01

    In animal husbandry, antibiotics are widely used to treat and prevent diseases or to promote growth. The use of antibiotics for domestic animals enables to promote safety of livestock products and enhance productivity. Tetracycline antibiotics (TCs) are one of the primarily used groups of antibiotics for cattle and swine. However, the unintentional spreading of antibiotics from animal waste to the environment may leave out drug residues, promoting resistant strains of bacteria, and will adversely affect the ecosystem and human health. To prevent the spread of veterinary antibiotics in the environment, it is required to treat residual antibiotics in livestock wastewater. In this study, we investigated the electrochemical oxidation of TCs to treat livestock wastewater. The concentrations of TCs in aqueous solutions were reduced from 100 mg/L to less than 0.6 mg/L by 6 h of electrochemical treatment using a Ti/IrO2 anode with Na2SO4 electrolyte. The concentration of oxytetracycline (OTC) in livestock wastewater was also reduced from 100 mg/L to less than 0.7 mg/L by the same treatment. Thus, the electrochemical oxidation using a Ti/IrO2 anode with Na2SO4 electrolyte was found to be effective for degradation of TCs. The results suggest that the electrochemical oxidation method is a promising treatment for TCs in livestock wastewater.

  18. Probing Structural Changes in Poly(3-hexylthiophene) (P3HT) During Electrochemical Oxidation with In Situ X-ray Scattering

    Science.gov (United States)

    Thelen, Jacob L.; Patel, Shrayesh N.; Javier, Anna E.; Balsara, Nitash P.

    2014-03-01

    Mixtures of poly(3-hexylthiophene)-b-poly(ethylene oxide) (P3HT-b-PEO) block copolymer and lithium bis(trifluromethanesulfonyl) imide (LiTFSI) salt can microphase separate into electron (P3HT) and ion (PEO/LiTFSI) conducting domains. P3HT is a semicrystalline polymer with intrinsically semiconducting electronic properties. Electrochemical oxidation (doping) of the P3HT block provides the P3HT-b-PEO/LiTFSI mixtures with electronic conductivity suitable for lithium battery operation. Due to the presence of the solid-state electrolyte (PEO/LiTFSI) in intimate contact with the microphase separated P3HT domains, electrochemical oxidation of P3HT can be performed entirely in the solid state; therefore, P3HT-b-PEO/LiTFSI provides a unique opportunity to study the structural changes in P3HT induced by oxidation. We use in situ x-ray scattering techniques to probe structural changes in P3HT during electrochemical oxidation and correlate these changes with previously observed enhancements in electron mobility. Supported by the Joint Center for Energy Storage Research (JCESR).

  19. Electrochemical oxidation of 3,5-di-tert-butylcatechol: Synthesis and characterization of the formed ortho-benzoquinhydrone derivative

    International Nuclear Information System (INIS)

    Nematollahi, D.; Shayani-Jam, H.

    2006-01-01

    Electrochemical oxidation of 3,5-di-tert-butylcatechol (1) has been studied in ethanol/water mixtures by means of cyclic voltammetry and controlled-potential coulometry. The results revealed that 3,5-di-tert-butyl-1,2-benenzoquinone (2) derived from oxidation of 3,5-di-tert-butylcatechol participate in noncovalently linked interactions with 1 converted to an ortho-benzoquinhydrone (3). The structure of 3 was characterized by MS, IR, 1 H NMR and 13 C NMR. The 1 H NMR studies reveal that the benzoquinhydrone complex 3 is stabilized by one H-bonding interaction. In this work we derived a novel ortho-bezoquinhydrone type complex (3) based on electrochemical oxidation of 3,5-di-tert-butylcatechol at carbon electrode in an undivided cell

  20. Preparation of AAO-CeO2 nanotubes and their application in electrochemical oxidation desulfurization of diesel

    Science.gov (United States)

    Du, Xiaoqing; Yang, Yumeng; Yi, Chenxi; Chen, Yu; Cai, Chao; Zhang, Zhao

    2017-02-01

    The coaxial arrays of AAO-CeO2 NTs have been successfully galvanostatically deposited on an anode, characterized and adopted as a catalyst for removing organic sulfurs from diesel. The influence of the main electrochemical oxidation factors on the efficiency of desulfurization have also been investigated. The results show that the fabrication process of AAO-CeO2 NTs is accompanied by the formation of a new phase, namely Al3Ce, and the main oxidation products of the diesel are soluble inorganic sulphides, especially Ce2(SO4)3. When compared with dibenzothiophene and 4, 6-dimethyldibenzothiophene, benzothiophene is much more easily removed, with a removal efficiency that reaches 87.2%. Finally, a possible electrochemical oxidation desulfurization pathway for diesel is proposed.

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

    Directory of Open Access Journals (Sweden)

    A. Benchettara

    2014-12-01

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

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

    Directory of Open Access Journals (Sweden)

    A. Benchettara

    2015-07-01

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

  3. Advanced manganese oxide material for rechargeable lithium cells

    Energy Technology Data Exchange (ETDEWEB)

    Atwater, Terrill B.; Salkind, Alvin J. [Rutgers University, Piscataway, NJ (United States)

    2006-11-22

    A family of potassium-doped manganese oxide materials were synthesized with the stoichiometric formula Li{sub 0.9-X}K{sub X}Mn{sub 2}O{sub 4}, where X=0.0-0.25 and evaluated for their viability as a cathode material for a rechargeable lithium battery. A performance maximum was found at X=0.1 where the initial specific capacity for the lithium-potassium-doped manganese dioxide electrochemical couple was 130mAhg{sup -1} of active cathode material. The discharge capacity of the system was maintained through 90 cycles (95% initial capacity). Additionally, the capacity was maintained at greater than 90% initial discharge through 200 cycles. Other variants demonstrated greater than 75% initial discharge through 200 cycles at comparable capacity. (author)

  4. Zinc oxide nanostructures: new properties for advances applications

    International Nuclear Information System (INIS)

    Lupan, Oleg; Chow, Lee; Pauporte, Thierry

    2011-01-01

    Zinc oxide is a material which exhibits a variety of new properties at nanometer dimensions. Various synthesis techniques have been carried out to provide growth of nanowires, nanorods, nanorings, nanosprings, and nanobelts of ZnO under various conditions. These nanostructures show that ZnO possesses probably the richest family of nanoarchitectures among all materials, including their structures and properties. Such nanoarchitectures are potential building blocks for novel applications in optoelectronics, sensors, photovoltaic and nano-biomedical sciences. This work presents a review of various nano architectures of ZnO grown by the electrochemical, hydrothermal and solid-vapor phase techniques and their properties. The possible applications of ZnO nanowires as sensors, nano-DSSC, photodetectors and nano-LEDs will be presented.

  5. Pseudocapacitive Oxides and Sulfides for High-Performance Electrochemical Energy Storage

    KAUST Repository

    Xia, Chuan

    2018-01-01

    The intermittent nature of several sustainable energy sources such as solar and wind energy has ignited the demand of electrochemical energy storage devices in the form of batteries and electrochemical capacitors. The future generation

  6. Preparation of copper (I) oxide nanohexagon decorated reduced graphene oxide nanocomposite and its application in electrochemical sensing of dopamine

    Energy Technology Data Exchange (ETDEWEB)

    Sivasubramanian, R., E-mail: rss@psgias.ac.in; Biji, P.

    2016-08-15

    Highlights: • Cu{sub 2}O nanohexagon–reduced graphene oxide (rGO) nanocomposite has been prepared by in-situ reduction method. • The rGO-Cu{sub 2}O/GCE exhibited excellent catalytic properties for dopamine due to the synergistic action of the nanocomposite. • The proposed sensor is highly selective toward dopamine in the presence of ascorbic acid and uric acid. - Graphical Abstract: - Abstract: An electrochemical sensor using copper (I) oxide nanostructure decorated reduced graphene oxide (rGO) nanocomposite has been proposed for selective detection of dopamine. The rGO–Cu{sub 2}O nanocomposite was synthesized by in-situ chemical reduction method and was characterized using Transmission Electron Microscope (TEM), Energy Dispersive X-ray (EDX) analysis, X-ray Diffraction (XRD) patterns, Fourier Transform Infrared (FTIR), UV–vis and Raman Spectroscopy, respectively. From Cyclic Voltammetric (CV) studies, it was inferred that rGO–Cu{sub 2}O/GCE exhibits excellent electrocatalytic activity toward dopamine, which is attributed to the enhanced conductivity as well as the synergistic effect of the nanocomposite. The sensing was carried out using Differential Pulse Voltammetry (DPV) wherefrom a Limit of Detection (LOD) of 50 nM with a linear range from 10 µM to 900 µM was estimated. The effect of potential interfering agents such as Uric Acid (UA), Ascorbic Acid (AA), glucose, K{sup +}, Na{sup +}, Cl{sup −}, and SO{sub 4}{sup −} ions toward sensing were investigated. The performance of the sensor toward the estimation of dopamine in human blood and urine samples were analyzed. The facile method for the preparation of a nanocomposite in conjunction with the low detection limit and the wide linear range for dopamine sensing is the advantage of this present study.

  7. Tribological performance of titanium samples oxidized by fs-laser radiation, thermal heating, or electrochemical anodization

    Science.gov (United States)

    Kirner, S. V.; Slachciak, N.; Elert, A. M.; Griepentrog, M.; Fischer, D.; Hertwig, A.; Sahre, M.; Dörfel, I.; Sturm, H.; Pentzien, S.; Koter, R.; Spaltmann, D.; Krüger, J.; Bonse, J.

    2018-04-01

    Commercial grade-1 titanium samples (Ti, 99.6%) were treated using three alternative methods, (i) femtosecond laser processing, (ii) thermal heat treatment, and (iii) electrochemical anodization, respectively, resulting in the formation of differently conditioned superficial titanium oxide layers. The laser processing (i) was carried out by a Ti:sapphire laser (pulse duration 30 fs, central wavelength 790 nm, pulse repetition rate 1 kHz) in a regime of generating laser-induced periodic surface structures (LIPSS). The experimental conditions (laser fluence, spatial spot overlap) were optimized in a sample-scanning setup for the processing of several square-millimeters large surface areas covered homogeneously by these nanostructures. The differently oxidized titanium surfaces were characterized by optical microscopy, micro Raman spectroscopy, variable angle spectroscopic ellipsometry, and instrumented indentation testing. The tribological performance was characterized in the regime of mixed friction by reciprocating sliding tests against a sphere of hardened steel in fully formulated engine oil as lubricant. The specific tribological performance of the differently treated surfaces is discussed with respect to possible physical and chemical mechanisms.

  8. Electrochemical oxidation of landfill leachate in a flow reactor: optimization using response surface methodology.

    Science.gov (United States)

    Silveira, Jefferson E; Zazo, Juan A; Pliego, Gema; Bidóia, Edério D; Moraes, Peterson B

    2015-04-01

    Response surface methodology based on Box-Behnken (BBD) design was successfully applied to the optimization in the operating conditions of the electrochemical oxidation of sanitary landfill leachate aimed for making this method feasible for scale up. Landfill leachate was treated in continuous batch-recirculation system, where a dimensional stable anode (DSA(©)) coated with Ti/TiO2 and RuO2 film oxide were used. The effects of three variables, current density (milliampere per square centimeter), time of treatment (minutes), and supporting electrolyte dosage (moles per liter) upon the total organic carbon removal were evaluated. Optimized conditions were obtained for the highest desirability at 244.11 mA/cm(2), 41.78 min, and 0.07 mol/L of NaCl and 242.84 mA/cm(2), 37.07 min, and 0.07 mol/L of Na2SO4. Under the optimal conditions, 54.99% of chemical oxygen demand (COD) and 71.07 ammonia nitrogen (NH3-N) removal was achieved with NaCl and 45.50 of COD and 62.13 NH3-N with Na2SO4. A new kinetic model predicted obtained from the relation between BBD and the kinetic model was suggested.

  9. Ferrate(VI) as a greener oxidant: Electrochemical generation and treatment of phenol.

    Science.gov (United States)

    Sun, Xuhui; Zhang, Qi; Liang, He; Ying, Li; Xiangxu, Meng; Sharma, Virender K

    2016-12-05

    Ferrate(VI) (Fe(VI)O4(2-), Fe(VI)) is a greener oxidant in the treatment of drinking water and wastewater. The electrochemical synthesis of Fe(VI) may be considered environmentally friendly because it involves one-step process to convert Fe(0) to Fe(VI) without using harmful chemicals. Electrolysis was performed by using a sponge iron as an anode in NaOH solution at different ionic strengths. The cyclic voltammetric (CV) curves showed that the sponge iron had higher electrical activity than the grey cast iron. The optimum current density was 0.054mAcm(-2) in 10M NaOH solution, which is much lower than the electrolyte concentrations used in other electrode materials. A comparison of current efficiency and energy consumption was conducted and is briefly discussed. The generated ferrate solution was applied to degrade phenol in water at two levels (2mgL(-1) and 5mgL(-1)). The maximum removal efficiency was ∼70% and the optimum pH for phenol treatment was 9.0. Experiments on phenol removal using conventional coagulants (ferric chloride (FeCl3) and polyaluminium chloride (PAC)) were performed independently to demonstrate that removal of phenol by Fe(VI) occurred mainly by oxidative transformation. A combination of Fe(VI) and coagulant may be advantageous in enhancing removal efficiency, adjusting pH, and facilitating flocculation. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Characterization and electrochemical application of carbon materials based on poly(phenylene oxide)

    Science.gov (United States)

    Gray, Hunter

    Carbon materials possess excellent electrical and surface properties for the next generation of energy storage devices. Polymers provide a carbon rich and tailorable precursor for the production of carbon materials. Therefore, activated carbons were prepared from poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) via a three step process: thermal oxidation, carbonization, and activation with KOH. The activated carbons are predominately microporous with BET specific surface areas up to 2638 m2/g. Impedance spectroscopy revealed these carbons possess electrical conductivities comparable to commercial carbon blacks and consequently were employed in thin-film composite electrodes in electrochemical double-layer capacitors. Cyclic voltammetry confirmed maximum specific capacitances of 13.23 F/g and 2.848 F/g for aqueous and organic electrolyte systems, respectively. Additionally, carbon nanotubes were synthesized from PPO and other polymers with a nickel catalyst via chemical vapor deposition as revealed by transmission electron microscopy. This is the first report of carbon nanotubes produced from PPO.

  11. Reduced graphene oxide-carbon dots composite as an enhanced material for electrochemical determination of dopamine

    International Nuclear Information System (INIS)

    Hu, Shirong; Huang, Qitong; Lin, Yi; Wei, Chan; Zhang, Hanqiang; Zhang, Wuxiang; Guo, Zhenbo; Bao, Xiuxiu; Shi, Jiangu; Hao, Aiyou

    2014-01-01

    In this study, we developed and characterized a new dopamine (DA) sensor based on the reduced graphene oxide (rGO)-carbon dot composite film with high sensitivity, nice specificity and good stability. The carbon dots (CDs) had carboxyl groups with negative charge, which not only provided good stability, but also enabled interaction with amine functional groups in DA through electrostatic interaction to enhance the specificity of DA with high specificity, and the interaction and electron communication between rGO and DA can be further strengthened via π-π stacking force. Under optimal conditions, the rGO-CDs electrode (GCE) showed better electrochemical response towards the detection of DA than the bare GCE, GO/GCE and CDs/GCE. A linear relationship between the oxidation peak current of DA and its concentration could be obtained in a range from 0.01000 μM to 450.0 μM with the limit of detection as 1.5 nM (3S/N). Furthermore, rGO-CDs/GCE exhibited good ability to suppress the background current from large excess ascorbic acid (AA) and uric acid (UA). Meanwhile, the rGO-CDs/GCE also was applied to the detection of DA content in the injection of DA with satisfactory results, and the biosensor could keep its activity for at least a month

  12. Electrochemical Determination of Paracetamol Using Fe3O4/Reduced Graphene-Oxide-Based Electrode

    Directory of Open Access Journals (Sweden)

    Nguyen Thi Anh Thu

    2018-01-01

    Full Text Available The synthesis of magnetic iron oxide/reduced graphene oxide (Fe3O4/rGO and its application to the electrochemical determination of paracetamol using Fe3O4/rGO modified electrode were demonstrated. The obtained materials were characterized by means of X-ray diffraction (XRD, nitrogen adsorption/desorption isotherms, X-ray photoelectron spectroscopy (XPS, transmission electron microscope (TEM, Fourier transform infrared spectroscopy (FTIR, and magnetic measurement. The results showed that Fe3O4/rGO composite exhibited high specific surface area, and its morphology consists of very fine spherical particles of Fe3O4 in nanoscales. Fe3O4/rGO was used as an electrode modifier for the determination of paracetamol by differential pulse-anodic stripping voltammetry (DP-ASV. The preparation of Fe3O4/rGO-based electrode and some factors affecting voltammetric responses were investigated. The results showed that Fe3O4/rGO is a potential electrode modifier for paracetamol detection by DP-ASV with a low limit of detection. The interfering effect of uric acid, ascorbic acid, and dopamine on the current response of paracetamol has been reported. The repeatability, reproducibility, linear range, and limit of detection were also addressed. The proposed method could be applied to the real samples with satisfactory results.

  13. Coating manganese oxide onto graphite electrodes by immersion for electrochemical capacitors

    International Nuclear Information System (INIS)

    Lin, C.-C.; Chen, H.-W.

    2009-01-01

    In this study, manganese oxide was coated on a graphite electrode by immersion. Durations for immersion were varied to control the amount of manganese oxide coated onto the electrode surface. Maximum capacitance of 556 mF cm -2 was obtained in 0.5 M LiCl and with better/superior conditions (immersion time = 80 min and potential scan rate = 10 mV s -1 ). In addition, cyclic voltammograms of the prepared electrode at different potential scan rates exhibited the approximately rectangular and symmetric current-potential characteristics of a capacitor. Furthermore, the chronopotentiometry (CP) charge-discharge curves of the electrode prepared at 80 min of immersion time with a constant current of 1 mA were symmetric and similar isosceles triangles, which demonstrate its high electrochemical reversibility and good stability. Finally, under scanning electron microscope (SEM), the surface of the electrode prepared at 80 min of immersion time and after 1500 cycles of potential cycling revealed that numerously three-dimensional network of macropores appeared on large spherical grains

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  15. High temperature oxidation and electrochemical studies on novel co-base superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Klein, Leonhard

    2013-02-27

    improved oxidation resistance due to their beneficial effect on Al{sub 2}O{sub 3} formation (especially at 900 C and higher) and due to additional generation of titanium- and silicon-rich phases, respectively, without altering the γ/γ'-microstructure. Moreover, the titanium-containing alloy is reported to exhibit excellent creep properties at 850 C and hence this material is expected to be the most promising alloy system for further optimisation. In contrast, additions of silicon lead to silicon-containing phases at the oxide/alloy interface, within precipitates, and at the grain boundaries, which are expected to impair the mechanical properties. Additions of nickel most probably enhance solubility of boron within the alloy matrix and therefore the previously described positive boron-effect gets eliminated. Based on knowledge of other alloy systems, small amounts of the rare earth element yttrium are reported to improve the oxidation resistance. However, 0.005 atomic percent of yttrium in Co-Al-W-B alloys do not lead to the expected effect, presumably due to insufficient amounts of the minor element. Electrochemical measurements on the unoxidised Co-Al-W-B superalloy and pure cobalt in aqueous solutions of different pH reveal significantly improved corrosion resistance with increasing pH value due to the formation of a duplex layer, i.e. Co{sub 3}O{sub 4} or CoOOH species on top of a Co(OH){sub 2} film. Upon polarisation, both materials show primary and secondary passivation in alkaline 0.1 M NaOH solution, whereas limited passivation can be observed in neutral 1 M Na{sub 2}SO{sub 4}, and active dissolution in acidic 0.5 M H{sub 2}SO{sub 4} solution. Further investigations in neutral 0.5 M NaCl solution reveal limited initial passivation followed by severe pitting corrosion at higher potentials. High temperature oxide scales on the alloy surface are highly efficient barriers against corrosive attack over the entire polarisation range from -1 V to +2 V (vs. Ag

  16. Pyro-Electrochemical Reduction of a Mixture of Rare Earth Oxides and NiO in LiCl molten Salt

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Min Woo; Jeong, Sang Mun [Department of Chemical Engineering, Chungbuk National University, Cheongju (Korea, Republic of)

    2017-06-15

    An electrochemical reduction of a mixture of NiO and rare earth oxides has been conducted to increase the reduction degree of rare earth oxides. Cyclic voltammetry (CV) measurement was carried out to determine the electrochemical reduction behavior of the mixed oxide in molten LiCl medium. Constant voltage electrolysis was performed with various supplied charges to understand the mechanism of electrochemical reduction of the mixed oxide as a working electrode. After completion of the electrochemical reduction, crystal structure of the reaction intermediates was characterized by using an X-ray diffraction method. The results clearly demonstrate that the rare earth oxide was converted to RE-Ni intermetallics via co-reduction with NiO.

  17. Electrochemical/chemical oxidation of bisphenol A in a four-electron/two-proton process in aprotic organic solvents

    International Nuclear Information System (INIS)

    Chan, Ya Yun; Yue, Yanni; Li, Yongxin; Webster, Richard D.

    2013-01-01

    Graphical abstract: - Highlights: • Bisphenol A undergoes a chemically irreversible voltammetric oxidation process. • Chemical oxidation was performed to overcome adsorption effects that cause electrode fouling. • A new product was isolated from chemical oxidation with 4 mol equiv. of the one-electron oxidant, NO + . • The oxidative mechanism was proposed to be a four-electron/two-proton process. - Abstract: The electrochemical behavior of bisphenol A (BPA) was examined using cyclic voltammetry, bulk electrolysis and chemical oxidation in aprotic organic solvents. It was found that BPA undergoes a chemically irreversible voltammetric oxidation process to form compounds that cannot be electrochemically converted back to the starting materials on the voltammetric timescale. To overcome the effects of electrode fouling during controlled potential electrolysis experiments, NO + was used as a one-electron chemical oxidant. A new product, hydroxylated bisdienone was isolated from the chemical oxidation of BPA with 4 mol equiv of NO + SbF 6 − in low water content CH 3 CN. The structure of the cation intermediate species was deduced and it was proposed that BPA is oxidized in a four-electron/two-proton process to form a relatively unstable dication which reacts quickly in the presence of water in acetonitrile (in a mechanism that is similar to phenols in general). However, as the water content of the solvent increased it was found that the chemical oxidation mechanism produced a nitration product in high yield. The findings from this study provide useful insights into the reactions that can occur during oxidative metabolism of BPA and highlight the possibility of the role of a bisdienone cation as a reactive metabolite in biological systems

  18. CFD analysis of a solid oxide fuel cell with internal reforming: Coupled interactions of transport, heterogeneous catalysis and electrochemical processes

    Science.gov (United States)

    Janardhanan, Vinod M.; Deutschmann, Olaf

    Direct internal reforming in solid oxide fuel cell (SOFC) results in increased overall efficiency of the system. Present study focus on the chemical and electrochemical process in an internally reforming anode supported SOFC button cell running on humidified CH 4 (3% H 2 O). The computational approach employs a detailed multi-step model for heterogeneous chemistry in the anode, modified Butler-Volmer formalism for the electrochemistry and Dusty Gas Model (DGM) for the porous media transport. Two-dimensional elliptic model equations are solved for a button cell configuration. The electrochemical model assumes hydrogen as the only electrochemically active species. The predicted cell performances are compared with experimental reports. The results show that model predictions are in good agreement with experimental observation except the open circuit potentials. Furthermore, the steam content in the anode feed stream is found to have remarkable effect on the resulting overpotential losses and surface coverages of various species at the three-phase boundary.

  19. Electrochemical oxidation of iron and alkalinity generation for efficient sulfide control in sewers.

    Science.gov (United States)

    Lin, Hui-Wen; Kustermans, Caroline; Vaiopoulou, Eleni; Prévoteau, Antonin; Rabaey, Korneel; Yuan, Zhiguo; Pikaar, Ilje

    2017-07-01

    The addition of iron salts is one of the most commonly used dosing strategies for sulfide control in sewers. However, iron salts decrease the sewage pH which not only reduces the effectiveness of sulfide precipitation but also enhances the release of residual sulfide to the sewer atmosphere. Equally important, concentrated iron salt solutions are corrosive and their frequent transport, handling, and on-site storage often come with Occupational Health and Safety (OH&S) concerns. Here, we experimentally demonstrated a novel sulfide control approach using electrochemical systems with parallel placed iron electrodes. This enabled combining anodic dissolved iron species release with cathodic hydroxyl anion production, which alleviates all the aforementioned concerns. A long-term experiment was successfully carried out achieving an average sulfide removal efficiency of 95.4 ± 4.4% at low voltage input of 2.90 ± 0.54 V over the course of 8 weeks. This electrochemical method was demonstrated to successfully achieve efficient sulfide control. In addition, it increases the sewage pH, thereby overcoming the drawbacks associated with the pH decrease in the case of conventional iron salt dosing. Ferrous ions were produced at an overall coulombic efficiency (CE) of 98.2 ± 1.2%, whereas oxygen evolution and direct sulfide oxidation were not observed. Short-term experiments showed that increasing either inter-electrode gap or current density increased the cell voltage associated with the increase in the ohmic drop of the system. Overall, this study highlights the practical potential of in-situ generation of dissolved iron species and simultaneous hydroxyl anion generation for efficient sulfide control in sewers. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. System Tb-Fe-O: thermodynamic properties of ternary oxides using solid-state electrochemical cells

    International Nuclear Information System (INIS)

    Rakshit, S.K.; Parida, S.C.; Dash, S.; Singh, Ziley; Prasad, R.; Venugopal, V.

    2003-01-01

    The standard molar Gibbs free energies of formation of TbFeO 3 (s) and Tb 3 Fe 5 O 12 (s) have been determined using solid-state electrochemical cell employing different solid electrolytes. The reversible emfs of the following solid-state electrochemical cells have been measured in the temperature range 1050≤T/K≤1250. Cell (I):(-)Pt/{TbFeO 3 (s)+Tb 2 O 3 (s)+Fe(s)}//YDT/CSZ//{Fe(s)+Fe 0.95 O(s)}/Pt(+))) (Cell (II):(-)Pt/{Fe(s)+Fe 0.95 O(s)}//CSZ//{TbFeO 3 (s)+Tb 3 Fe 5 O 12 (s)+Fe 3 O 4 (s)}/Pt(+) The oxygen chemical potentials corresponding to the three-phase equilibria involving the ternary oxides have been computed from the emf data. The standard molar Gibbs free energies of formation of solid TbFeO 3 and Tb 3 Fe 5 O 12 calculated by the least-squares regression analysis of the data obtained in the present study are given by {Δ f G compfn m (TbFeO 3 ,s)/(kJ·mol -1 )±3.2}=-1357.5+0.2531·(T/K); (1050≤T/K≤1548);))and({Δ f G compfn m (Tb 3 Fe 5 O 12 ,s)/(kJ·mol -1 )±3.5}=-4901.7+ 0.9997·(T/K); (1050≤T/K≤1250).)) The uncertainty estimates for Δ f G compfn m include the standard deviation in the emf and uncertainty in the data taken from the literature. Based on the thermodynamic information, oxygen potential diagram and chemical potential diagrams were computed for the system Tb-Fe-O at T=1250 K

  1. Detailed dynamic solid oxide fuel cell modeling for electrochemical impedance spectra simulation

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, Ph. [Laboratory of Steam Boilers and Thermal Plants, School of Mechanical Engineering, Thermal Engineering Section, National Technical University of Athens, Heroon Polytechniou 9, 15780 Athens (Greece); Panopoulos, K.D. [Institute for Solid Fuels Technology and Applications, Centre for Research and Technology Hellas, 4th km. Ptolemais-Mpodosakeio Hospital, Region of Kouri, P.O. Box 95, GR 502, 50200 Ptolemais (Greece)

    2010-08-15

    This paper presents a detailed flexible mathematical model for planar solid oxide fuel cells (SOFCs), which allows the simulation of steady-state performance characteristics, i.e. voltage-current density (V-j) curves, and dynamic operation behavior, with a special capability of simulating electrochemical impedance spectroscopy (EIS). The model is based on physico-chemical governing equations coupled with a detailed multi-component gas diffusion mechanism (Dusty-Gas Model (DGM)) and a multi-step heterogeneous reaction mechanism implicitly accounting for the water-gas-shift (WGS), methane reforming and Boudouard reactions. Spatial discretization can be applied for 1D (button-cell approximation) up to quasi-3D (full size anode supported cell in cross-flow configuration) geometries and is resolved with the finite difference method (FDM). The model is built and implemented on the commercially available modeling and simulations platform gPROMS trademark. Different fuels based on hydrogen, methane and syngas with inert diluents are run. The model is applied to demonstrate a detailed analysis of the SOFC inherent losses and their attribution to the EIS. This is achieved by means of a step-by-step analysis of the involved transient processes such as gas conversion in the main gas chambers/channels, gas diffusion through the porous electrodes together with the heterogeneous reactions on the nickel catalyst, and the double-layer current within the electrochemical reaction zone. The model is an important tool for analyzing SOFC performance fundamentals as well as for design and optimization of materials' and operational parameters. (author)

  2. Methanol oxidation reaction on core-shell structured Ruthenium-Palladium nanoparticles: Relationship between structure and electrochemical behavior

    Science.gov (United States)

    Kübler, Markus; Jurzinsky, Tilman; Ziegenbalg, Dirk; Cremers, Carsten

    2018-01-01

    In this work the relationship between structural composition and electrochemical characteristics of Palladium(Pd)-Ruthenium(Ru) nanoparticles during alkaline methanol oxidation reaction is investigated. The comparative study of a standard alloyed and a precisely Ru-core-Pd-shell structured catalyst allows for a distinct investigation of the electronic effect and the bifunctional mechanism. Core-shell catalysts benefit from a strong electronic effect and an efficient Pd utilization. It is found that core-shell nanoparticles are highly active towards methanol oxidation reaction for potentials ≥0.6 V, whereas alloyed catalysts show higher current outputs in the lower potential range. However, differential electrochemical mass spectrometry (DEMS) experiments reveal that the methanol oxidation reaction on core-shell structured catalysts proceeds via the incomplete oxidation pathway yielding formaldehyde, formic acid or methyl formate. Contrary, the alloyed catalyst benefits from the Ru atoms at its surface. Those are found to be responsible for high methanol oxidation activity at lower potentials as well as for complete oxidation of CH3OH to CO2 via the bifunctional mechanism. Based on these findings a new Ru-core-Pd-shell-Ru-terrace catalyst was synthesized, which combines the advantages of the core-shell structure and the alloy. This novel catalyst shows high methanol electrooxidation activity as well as excellent selectivity for the complete oxidation pathway.

  3. A miniaturized electrochemical toxicity biosensor based on graphene oxide quantum dots/carboxylated carbon nanotubes for assessment of priority pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xiaolin; Wu, Guanlan; Lu, Nan [School of Environment, Northeast Normal University, Changchun 130117 (China); Yuan, Xing, E-mail: yuanx@nenu.edu.cn [School of Environment, Northeast Normal University, Changchun 130117 (China); Li, Baikun, E-mail: baikun@engr.uconn.edu [Department of Civil and Environmental Engineering, University of Connecticut, Storrs, CT 06269 (United States)

    2017-02-15

    Highlights: • Graphene oxide quantum dots/carboxylated carbon nanotubes hybrid was developed. • The cytotoxicity detection vessel was miniaturized to the 96-well plate. • The electrochemical behavior of HepG2 cell was investigated for the first time. • The mixture signal of adenine and hypoxanthine was separated successfully. • The biosensor was used to assess the toxicity of heavy metals and phenols. - Abstract: The study presented a sensitive and miniaturized cell-based electrochemical biosensor to assess the toxicity of priority pollutants in the aquatic environment. Human hepatoma (HepG2) cells were used as the biological recognition agent to measure the changes of electrochemical signals and reflect the cell viability. The graphene oxide quantum dots/carboxylated carbon nanotubes hybrid was developed in a facile and green way. Based on the hybrid composite modified pencil graphite electrode, the cell culture and detection vessel was miniaturized to a 96-well plate instead of the traditional culture dish. In addition, three sensitive electrochemical signals attributed to guanine/xanthine, adenine, and hypoxanthine were detected simultaneously. The biosensor was used to evaluate the toxicity of six priority pollutants, including Cd, Hg, Pb, 2,4-dinitrophenol, 2,4,6-trichlorophenol, and pentachlorophenol. The 24 h IC{sub 50} values obtained by the electrochemical biosensor were lower than those of conventional MTT assay, suggesting the enhanced sensitivity of the electrochemical assay towards heavy metals and phenols. This platform enables the label-free and sensitive detection of cell physiological status with multi-parameters and constitutes a promising approach for toxicity detection of pollutants. It makes possible for automatical and high-throughput analysis on nucleotide catabolism, which may be critical for life science and toxicology.

  4. Electrochemical oxidation and electroanalytical determination of xylitol at a boron-doped diamond electrode.

    Science.gov (United States)

    Lourenço, Anabel S; Sanches, Fátima A C; Magalhães, Renata R; Costa, Daniel J E; Ribeiro, Williame F; Bichinho, Kátia M; Salazar-Banda, Giancarlo R; Araújo, Mário C U

    2014-02-01

    Xylitol is a reduced sugar with anticariogenic properties used by insulin-dependent diabetics, and which has attracted great attention of the pharmaceutical, cosmetics, food and dental industries. The detection of xylitol in different matrices is generally based on separation techniques. Alternatively, in this paper, the application of a boron-doped diamond (BDD) electrode allied to differing voltammetric techniques is presented to study the electrochemical behavior of xylitol, and to develop an analytical methodology for its determination in mouthwash. Xylitol undergoes two oxidation steps in an irreversible diffusion-controlled process (D=5.05 × 10(-5)cm(2)s(-1)). Differential pulse voltammetry studies revealed that the oxidation mechanism for peaks P1 (3.4 ≤ pH ≤ 8.0), and P2 (6.0 ≤ pH ≤ 9.0) involves transfer of 1H(+)/1e(-), and 1e(-) alone, respectively. The oxidation process P1 is mediated by the (•)OH generated at the BDD hydrogen-terminated surface. The maximum peak current was obtained at a pH of 7.0, and the electroanalytical method developed, (employing square wave voltammetry) yielded low detection (1.3 × 10(-6) mol L(-1)), and quantification (4.5 × 10(-6) mol L(-1)) limits, associated with good levels of repeatability (4.7%), and reproducibility (5.3%); thus demonstrating the viability of the methodology for detection of xylitol in biological samples containing low concentrations. © 2013 Elsevier B.V. All rights reserved.

  5. SnO{sub 2}/reduced graphene oxide composite films for electrochemical applications

    Energy Technology Data Exchange (ETDEWEB)

    Bondarenko, E.A. [Belarusian State University, Nezalezhnastsi Av. 4, Minsk 220030 (Belarus); Mazanik, A.V., E-mail: mazanikalexander@gmail.com [Belarusian State University, Nezalezhnastsi Av. 4, Minsk 220030 (Belarus); Streltsov, E.A. [Belarusian State University, Nezalezhnastsi Av. 4, Minsk 220030 (Belarus); Kulak, A.I., E-mail: kulak@igic.bas-net.by [Institute of General and Inorganic Chemistry, National Academy of Sciences of Belarus, Surganova str., 9/1, Minsk 220072 (Belarus); Korolik, O.V. [Belarusian State University, Nezalezhnastsi Av. 4, Minsk 220030 (Belarus)

    2015-12-15

    Highlights: • SnO{sub 2}/GO composites with mass fraction of carbon phase 0.01% ≤ w{sub C} ≤ 80% have been formed. • 400 °C annealing was applied for GO reduction in the composites. • SnO{sub 2}/rGO composites demonstrate a high electrocatalytic activity in anodic processes. • Exchange current density grows linearly with carbon phase concentration at w{sub C} ≤ 10%. - Abstract: SnO{sub 2}/GO (GO is graphene oxide) composite films with GO mass fraction w{sub C} ranging from 0.01 to 80% have been prepared using colloidal solutions. Heat treatment of SnO{sub 2}/GO films in Ar atmosphere at 400 °C leads to GO reduction accompanied by partial exfoliation and decreasing of the particle thickness. SnO{sub 2}/rGO (rGO is reduced GO) film electrodes demonstrate a high electrocatalytic activity in the anodic oxidation of inorganic (iodide-, chloride-, sulfite-anions) and organic (ascorbic acid) substances. The increase of the anodic current in these reactions is characterized by overpotential inherent to the individual rGO films and exchange current density grows linearly with rGO concentration at w{sub C} ≤ 10% indicating that the rGO particles in composites act as sites of electrochemical process. The SnO{sub 2}/rGO composite films, in which the chemically stable oxide matrix encapsulates the rGO inclusions, can be considered as a promising material for applied electrochemistry.

  6. Square-wave stripping