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George Z. Chen - One of the best experts on this subject based on the ideXlab platform.
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electrochemical investigation of novel Reference Electrode ni ni oh in comparison with silver and platinum inert quasi Reference Electrodes for electrolysis in eutectic molten hydroxide
International Journal of Hydrogen Energy, 2019Co-Authors: Nawar K Alshara, Farooq Sher, Aqsa Yaqoob, George Z. ChenAbstract:Abstract An efficient and green energy carrier hydrogen (H2) generation via water splitting reaction has become a major area of focus to meet the demand of clean and sustainable energy sources. In this research, the splitting steam via eutectic molten hydroxide (NaOH–KOH; 49–51 mol%) electrolysis for hydrogen gas production has been electrochemically investigated at 250–300 °C. Three types of Reference Electrodes such as a high-temperature mullite membrane Ni/Ni(OH)2, quasi-silver and quasi-platinum types were used. The primary purpose of this Electrode investigation was to find a suitable, stable, reproducible and reusable Reference Electrode in a molten hydroxide electrolyte. Cyclic voltammetry was performed to examine the effect on reaction kinetics and stability to control the working Electrode at different scan rate and molten salt temperature. The effect of introducing water to the eutectic molten hydroxide via the Ar gas stream was also investigated. When the potential scan rate was changed from 50 to 150 mV s−1, the reduction current for the platinum wire working Electrode was not changed with newly prepared nickel Reference Electrode that designates its stability and reproducibility. Furthermore, increasing the operating temperature of molten hydroxides from 250 to 300 °C the reduction potential of the prepared nickel Reference Electrode is slightly positive shifted about 0.02 V. This suggests that it has good stability with temperature variations. The prepared nickel and Pt Reference Electrode exhibited stable and reliable cyclic voltammetry results with and without the presence of steam in the eutectic molten hydroxide while Ag Reference Electrode exposed positive shifts of up to 0.1 V in the reduction potential. The designed Reference Electrode had a more stable and effective performance towards controlling the platinum working Electrode as compared to the other quasi-Reference Electrodes. Consequently, splitting steam via molten hydroxides for hydrogen has shown a promising alternative to current technology for hydrogen production that can be used for thermal and electricity generation.
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Electrochemical investigation of novel Reference Electrode Ni/Ni(OH)₂ in comparison with silver and platinum inert quasi-Reference Electrodes for electrolysis in eutectic molten hydroxide
International Journal of Hydrogen Energy, 2019Co-Authors: Nawar K. Al-shara, Farooq Sher, Aqsa Yaqoob, George Z. ChenAbstract:Abstract An efficient and green energy carrier hydrogen (H2) generation via water splitting reaction has become a major area of focus to meet the demand of clean and sustainable energy sources. In this research, the splitting steam via eutectic molten hydroxide (NaOH–KOH; 49–51 mol%) electrolysis for hydrogen gas production has been electrochemically investigated at 250–300 °C. Three types of Reference Electrodes such as a high-temperature mullite membrane Ni/Ni(OH)2, quasi-silver and quasi-platinum types were used. The primary purpose of this Electrode investigation was to find a suitable, stable, reproducible and reusable Reference Electrode in a molten hydroxide electrolyte. Cyclic voltammetry was performed to examine the effect on reaction kinetics and stability to control the working Electrode at different scan rate and molten salt temperature. The effect of introducing water to the eutectic molten hydroxide via the Ar gas stream was also investigated. When the potential scan rate was changed from 50 to 150 mV s−1, the reduction current for the platinum wire working Electrode was not changed with newly prepared nickel Reference Electrode that designates its stability and reproducibility. Furthermore, increasing the operating temperature of molten hydroxides from 250 to 300 °C the reduction potential of the prepared nickel Reference Electrode is slightly positive shifted about 0.02 V. This suggests that it has good stability with temperature variations. The prepared nickel and Pt Reference Electrode exhibited stable and reliable cyclic voltammetry results with and without the presence of steam in the eutectic molten hydroxide while Ag Reference Electrode exposed positive shifts of up to 0.1 V in the reduction potential. The designed Reference Electrode had a more stable and effective performance towards controlling the platinum working Electrode as compared to the other quasi-Reference Electrodes. Consequently, splitting steam via molten hydroxides for hydrogen has shown a promising alternative to current technology for hydrogen production that can be used for thermal and electricity generation.
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a quartz sealed ag agcl Reference Electrode for cacl2 based molten salts
Journal of Electroanalytical Chemistry, 2005Co-Authors: Dihua Wang, Xiaohong Hu, George Z. ChenAbstract:A quartz sealed Ag/AgCl Reference Electrode was fabricated and studied in CaCl2 based molten salts. It performed satisfactorily in terms of reproducibility, reusability and stability in experiments that varied the temperature (700–950 °C) and service time (from hours to days). The electric resistance of the Reference Electrode decreased from 105 to 103 Ω when increasing the molten salt temperature from 600 to 950 °C, following well Arrhenius’ Law. The potential variation of the Electrode upon changing the electrolyte composition (CaCl2, NaCl, KCl, and/or AgCl) suggested the selective conduction of Na+ ions and possibly Ca2+ ions through the thin-wall of the sealed quartz tube. Prolonged use (two to three days) of the Reference Electrode in the presence of both oxygen and molten chloride salt led to noticeable erosion of the quartz tube, particularly at the molten salt–quartz–gas triple phase boundary, which can be attributed to the formation of calcium and/or sodium silicates under the influence of oxygen present in the liquid and gas phases, respectively.
Joan Ramon Morante - One of the best experts on this subject based on the ideXlab platform.
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operando studies of all vanadium flow batteries easy to make Reference Electrode based on silver silver sulfate
Journal of Power Sources, 2014Co-Authors: Edgar Ventosa, Marcel Skoumal, Francisco Javier Vazquez, Cristina Flox, Joan Ramon MoranteAbstract:Abstract In-depth evaluation of the electrochemical performance of all-vanadium redox flow batteries (VRFBs) under operando conditions requires the insertion of a reliable Reference Electrode in the battery cell. In this work, an easy-to-make Reference Electrode based on silver–silver sulfate is proposed and described for VRFBs. The relevance and feasibility of the information obtained by inserting the Reference Electrode is illustrated with the study of ammoxidized graphite felts. In this case, we show that the kinetic of the electrochemical reaction VO2+/VO2+ is slower than that of V2+/V3+ at the Electrode. While the slow kinetics at the positive Electrode limits the voltage efficiency, the operating potential of the negative Electrode, which is outside the stability widow of water, reduces the coulombic efficiency due to the hydrogen evolution.
Andrzej Lewenstam - One of the best experts on this subject based on the ideXlab platform.
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An analytical quality solid-state composite Reference Electrode
Analyst, 2013Co-Authors: Zekra Mousavi, Kim Granholm, Tomasz Sokalski, Andrzej LewenstamAbstract:A new type of all-solid-state Reference Electrode was designed and characterized. The Electrodes are based on a polymer/inorganic salt composite and a silver/silver chloride Reference element. A rigorous testing procedure was used to reveal the possible influence of pH, solution composition, as well as the concentration and mobility of ions. The tests demonstrated the insensitivity of the Electrodes to the matrix effects, excellent stability of the potential readings, and significantly reduced leakage of inorganic salt. In the performed tests the composite Reference Electrodes were on a par with or better than the high-quality commercial Reference Electrodes. The Reference Electrodes described here are of analytical quality allowing for continuous, prolonged, and intensive usage.
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ionic liquid based liquid junction free Reference Electrode
Electroanalysis, 2011Co-Authors: Dimitrije Cicmil, Salzitsa Anastasova, Andrew Kavanagh, Ulriika Mattinen, Johan Bobacka, Andrzej Lewenstam, Dermot Diamond, Aleksandar RaduAbstract:In this paper, we describe a new type of polymer membrane-based Reference Electrode (RE) based on ionic liquids (ILs), in both liquid-contact (LCRE) and solid-contact Reference Electrode (SCRE) forms. The ILs used were bis(trifluoromethane sulfonyl)amid with 1-alkyl-3-methyl-imidazolium as well as phosphonium and ammonium cations. In addition to their charge stabilisation role, it was found that the ILs also functioned as effective plasticizers in the PVC matrix. The LCREs and SCREs were prepared using the same design as their corresponding indicator Electrodes. LCREs were prepared by casting in glass rings while SCREs were prepared on platforms made using screenprinting technology, with poly(3-octylthiophene-2,5 diyl) (POT) as the intermediate polymer. After potentiometric characterization of the response mechanism, the practical performance of the REs was studied using potentiometric titrations (Pb 2 + and pH), and characterised using cyclic voltammetry and impedance spectroscopy. All results were compared via parallel experiments in which the novel RE was substituted by a conventional double junction Ag/ AgCl Reference Electrode. The mechanism of response is most likely based on a limited degree of partitioning of IL ions into the sample thereby defining aquo-membrane interfacial potential. Despite their simple nature and construction, the REs showed excellent signal stability, and performed well in the analytical experiments. The identical mode of fabrication to that of the equivalent indicator (or Ion-Selective Electrode, ISE) will facilitate mass-production of both indicator and Reference Electrode using the same fabrication line, the only difference being the final capping membrane composition.
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junction less Reference Electrode for potentiometric measurements obtained by buffering ph in a conducting polymer matrix
Analyst, 2005Co-Authors: Teresa Blaz, Andrzej Lewenstam, Jan MigdalskiAbstract:A Reference Electrode for potentiometric measurements based on conducting polymers (CP) doped with pH buffering ligands is described. Both the CPs and doping ligands are selected and adjusted in such a way that possible ionic and redox sensitivity is hampered, while the pH buffering property of the CP film is exposed. In this way, the electric potential drop at the conducting polymer|solution interface is stabilized and close to constant over a certain pH range. The Electrode behaves as a pseudo-Reference Electrode in amphiprotic solvents or their mixtures, e.g. water–alcohol mixtures. For the first time titration of sulfates with lead(II) in water–methanol solution using two “plastic” Electrodes, CP-based Pb2+-sensitive indicator and CP-based Reference Electrode, is shown. Because the Electrode is junction-less it may easily be miniaturized and maintained and thus may serve in frontier applications of sensors.
Taek Dong Chung - One of the best experts on this subject based on the ideXlab platform.
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nanoporous platinum solid state Reference Electrode with layer by layer polyelectrolyte junction for ph sensing chip
Lab on a Chip, 2011Co-Authors: Sejin Park, Taek Dong ChungAbstract:A novel solid-state Reference Electrode was developed by combining nanoporous Pt with polyelectrolyte junction. The polyelectrolyte junction was formed in the microchannel connecting the nanoporous Pt and the sample solution, and had layer-by-layer structure of oppositely charged polyelectrolytes. The layer-by-layer polyelectrolyte junction effectively blocked the mass transport of ions and maintains constant pH environments on the surface of the nanoporous Pt. The assembly of the polyelectrolyte junction and the nanoporous Pt, which produced reportedly a stable open-circuit potential in response to constant pH, exhibited outstanding performance as a solid-state Reference Electrode (e.g., excellent reproducibility of ±4 mV (n = 5), good long term stability of ±1 mV (for 50 h), and independence of solution environments like pH and ionic strength). A working principle of the solid-state Reference Electrode with layer-by-layer polyelectrolyte junction was suggested in terms of the roles of each layer and the effect of the neighboring layer. As a demonstrative application of the solid-state Reference Electrode, a miniaturized chip-type solid-state pH sensor comprised of two nanoporous Pt Electrodes and a micro-patterned layer-by-layer polyelectrolyte junction was developed. The solid-state pH sensing chip showed reliable pH responses without liquid junction and successfully worked in a variety of buffers, beverages, and biological samples, showing its potential utility for practical applications. In addition, the solid-state pH sensing chip was integrated in a microfluidic system to be utilized for pH monitoring in microfluidic flow.
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a miniaturized electrochemical system with a novel polyelectrolyte Reference Electrode and its application to thin layer electroanalysis
Sensors and Actuators B-chemical, 2006Co-Authors: Taek Dong ChungAbstract:Abstract Miniaturized liquid junction Reference Electrodes with short- and long-term stabilities were fabricated by using photopolymerization of a patterned polyelectrolytic hydrogel, poly diallyldimethylammonium chloride (pDADMAC). Internal and external solutions were separated by the polyelectrolytic hydrogel barrier, through which Cl − ions carried the ionic current. The impedance spectrum of the developed hydrogel-based salt bridge was flat at 40 kΩ, indicating negligible capacitance. Most of thin film-type Reference Electrodes patterned on microfluidic chips suffer from a short lifespan and complicated structure, which seriously antagonize the advantages of electrochemical detection. The novel Reference Electrode system using a polyelectrolyte salt bridge on a microfluidic chip maintained a reproducible potential of 19.3 ± 6 mV versus a commercial Ag/AgCl Reference Electrode over 30 h. Anionic interferents such as Br − , I − , and S 2− ions had no influence on the performance of the Reference Electrode. In particular, the dependence on the Cl − ion concentration was substantially suppressed by separating the Ag/AgCl wire from the sample solution with the salt bridge. A 10 μm-thick cell with a polyelectrolyte salt bridge on a microfluidic chip showed the typical voltammetric behavior of thin layer cells that was confirmed by cyclic voltammetry (CV). This chip-based thin layer cell was exploited to determine the concentration of dopamine by differential pulse voltammetry (DPV) as well. A linear current response was observed down to 5 μM dopamine and the limit of detection was calculated to 2 μM.
G G Scherer - One of the best experts on this subject based on the ideXlab platform.
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electrochemical impedance spectroscopy applied to polymer electrolyte fuel cells with a pseudo Reference Electrode arrangement
Electrochimica Acta, 2006Co-Authors: H Kuhn, Bernhard Andreaus, Alexander Wokaun, G G SchererAbstract:Abstract The nature of the solid electrolyte and the low Electrode–Electrode gap in polymer electrolyte fuel cells (PEFCs) makes it difficult to introduce a Reference Electrode into the fuel cell in order to separate anodic and cathodic overpotential contributions. A suitable experimental setup should not disturb the current distribution in the fuel cell. In order to satisfy the boundary conditions, we introduced a pseudo Reference Electrode into the fuel cell. With this setup, we have measured the impedance of both Electrodes separately with respect to the pseudo Reference Electrode at different current densities. A state-space model was used to study the hydrogen oxidation reaction in order to identify kinetic parameters.
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electrochemical impedance spectroscopy applied to polymer electrolyte fuel cells with a pseudo Reference Electrode arrangement
Electrochimica Acta, 2006Co-Authors: H Kuhn, Bernhard Andreaus, Alexander Wokaun, G G SchererAbstract:Abstract The nature of the solid electrolyte and the low Electrode–Electrode gap in polymer electrolyte fuel cells (PEFCs) makes it difficult to introduce a Reference Electrode into the fuel cell in order to separate anodic and cathodic overpotential contributions. A suitable experimental setup should not disturb the current distribution in the fuel cell. In order to satisfy the boundary conditions, we introduced a pseudo Reference Electrode into the fuel cell. With this setup, we have measured the impedance of both Electrodes separately with respect to the pseudo Reference Electrode at different current densities. A state-space model was used to study the hydrogen oxidation reaction in order to identify kinetic parameters.
