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For extraction of metallic lanthanum from molten NaCl-CsCl-LaCl3 solutions, the electrochemical reduction of La(III) ions on inert Mo and liquid Ga electrodes were explored. Transient electrochemical techniques have been used to explore the reduction mechanism, transport parameters and thermodynamics properties. The obtained results indicate that the electrochemical reaction of La(III) + 3ē → La on inert electrode is a single-stage irreversible process, which controlled by the charge transfer rate. Simultaneously, the diffusion coefficient of [LaCl6] 3− complex ions was obtained at different temperatures. The apparent standard potentials of La3+/La couple and La-Ga alloy vs the temperature were determined. The base thermodynamic properties of lanthanum compounds were calculated. Furthermore, the potentiostatic method of electrolysis was used for the synthesis of La-Ga alloys. [ABSTRACT FROM AUTHOR]

The purpose of this work is to study the electrochemical behavior of uranium and cerium in fused In/3LiCl-2KCl system in the temperature range of 723–823 K by open-circuit potentiometry. The apparent electrode potential of Ce3+/Ce (U4+/U) couples and apparent standard potential of Ce-In (U-In) alloys vs AgCl/Ag reference electrode were established. The principal thermodynamic properties, activity and solubility of cerium and uranium were determined. The separation factor of uranium/cerium couple on liquid indium electrode was calculated. The experimental results have been shown that a lower temperature should be more effective for the separation uranium from cerium. [ABSTRACT FROM AUTHOR]

The intermetallic compound formations of Co–Ln (Ce, Pr, Gd, Dy and Er) in the molten LiCl-KCl eutectic at 873 K for an electrolytic reduction process was investigated with various electrochemical techniques of cyclic voltammetry, square wave voltammetry and open-circuit chronopotentiometry. The deposited Co–Ln alloy samples were prepared by potentiostatic electrolysis and further characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDS). A mathematical model about the equilibrium potentials of Co–Ln intermetallic compounds and atomic radius was proposed in this work. The fitted equation is Y = 0.1402X − 0.6457 (R² = 0.992). Because of the close similarity of chemical properties, the equilibrium potentials of Co–An intermetallic compounds can be simulated and predicted through the mathematical equation. In addition, the relationship between the equilibrium potentials and atomic radius of Ni–Ln and Cu–Ln alloy compounds were also in accordance with the mathematical model, while show a good linear relationship. The work described here can broaden the applications of mathematical model and highlight its potentials in future molten salt electrolysis based spent fuel pyroprocessing. [ABSTRACT FROM AUTHOR]

The article focuses on silver-coated chitosan enhanced performance of pyrrolidone-based ionic liquid oxygen sensor. Topics inlcude the ionic liquids (ILs) have been widely applied for the excellent physical and chemical properties, the imidazole-based ILs have been employed to improve the performance of electrochemical sensors because of their simple construction and the preparation procedure, and the ILs with excellent properties could be used as electrolyte for electrochemical sensors.

Room temperature ionic liquids (RTILs) possess superior physical and chemical properties, such as thermal stability and a wide electrochemical potential window. Because of these advantages, RTILS offer potential as a new generation of electrochemical gas sensor electrolytes. 1-butyl-3-methyl imidazole tetrafluorborate ([BMIM][BF4]) has been proven to be a useful electrolyte for an oxygen sensor; however, the leakage problem of [BMIM][BF4] will corrode the circuit and reduce the life of the sensor. This is also inconvenient for the transportation of sensors. In this paper, by adding a polymer to RTILs, a microporous film was produced to improve the linearity of the sensor response to oxygen; as a result, the electrical properties surpass those of a solid polymer electrolyte. The double-layer ionic liquid film (DLILF) with excellent linear regression coefficient and stability was obtained by combining PMMA/IL microporous film with PVDF/IL microporous film. The linear regression coefficient (R2) of plotted oxygen concentration vs. peak current is 0.995, although the response current of the electrolyte decreases. Our study indicates that the addition of RTILs to the mixture improves the electrical properties of the polymers and increases the linear relationship between the response current and oxygen concentration; the synergism of different polymers also enhances electrochemical oxygen sensor performance. [ABSTRACT FROM AUTHOR]

To extract terbium from LiCl-KCl-TbCl3 molten salts, the electrochemistry of Tb(III) was investigated on Cu and Zn coated W electrodes by a range of electrochemical techniques. A depolarization effect for Tb(III) reduction was observed on the two electrodes owing to the formation of Cu-Tb and Zn-Tb intermetallics. The Gibbs energies of formation for Zn12Tb and Cu5Tb were calculated by open circuit chronopotentiomery, and ΔGϴf (Zn12Tb) < ΔGϴf (Cu5Tb) showed that the formation of Zn12Tb on Zn electrode is easier than the one of Cu5Tb on Cu electrode. The exchange current intensities for Tb(III)/Zn12Tb and Tb(III)/Cu5Tb couples were estimated using linear polarization technique. It was found that j0(Tb(III)/Zn12Tb) > j0(Tb(III)/Cu5Tb), which revealed that the reaction rate of Tb(III) on Zn electrode is faster than that on Cu electrode. The electroextraction of Tb was conducted on the two electrodes under the same conditions, and the extraction rates and efficiencies on liquid Zn electrode are higher than those on Cu electrode when electroextraction time is less than 3 h. The products were checked by XRD and SEM with EDS, and are comprised of Zn and Zn17Tb2 in the Zn-Tb alloy and CuTb and Cu2Tb in Cu-Tb alloy, respectively. [ABSTRACT FROM AUTHOR]

The electrochemical behavior of Ho (III) on Cu electrode was analyzed by transient electrochemical techniques. Cyclic voltammetry and square wave voltammetry experiments indicated that the deposition potential of Ho (III) shift toward more positive values on Cu electrode because of the formation of Cu-Ho intermetallic compounds. According to the results of open circuit chronopotentiometry, the thermodynamic data, such as standard molar Gibbs free energy, enthalpy and entropy of formation for each Cu-Ho intermetallics were calculated in the temperature of 773-893 K. Moreover, potentiostatic and galvanostatic electrolysis was conducted to extract holmium from molten slat on Cu electrode at 773 K. The extraction efficiency of Ho was found to be about 99.37% by potentiostatic electrolysis at -2.15 V for 20 h. The phase composition and morphology of the extraction products were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDS). The results revealed that Cu-Ho intermetallic compounds, Cu0.99Ho0.01, Cu5Ho and Cu2Ho were formed during electrochemical extraction. The effect of the applied potential on the formation rate of Cu-Ho layer was investigated. [ABSTRACT FROM AUTHOR]

The electrochemical reduction of Ho (III) on W electrode and liquid Bi film electrode was investigated in LiCl-KCl eutectic by various electrochemical techniques. The reduction reaction of Ho (III) was found to be diffusion-controlled process with three electrons exchanged, which was considered as quasi-reversible. The diffusion coefficient of Ho (III) was determined by cyclic voltammetry and chronopotentiometry. The results of cyclic voltammetry and square wave voltammetry obtained on Bi film electrode exhibited two new reduction peaks at less negative potential than that on W electrode due to the formation of different Ho-Bi intermetallic compounds. Furthermore, the thermodynamic properties on the formation of Ho-Bi intermetallic compounds were measured using open circuit chronopotentiometry in the temperature range from 773 K to 863 K. The electroextraction of holmium was performed on liquid Bi electrode by potentiostatic and galvanostatic electrolysis. The extractive products were characterized by scanning electron microscopy and energy dispersive spectrometry (SEM-EDS) and X-ray diffraction (XRD). It was showed that Ho-Bi alloys consisted of HoBi and Bi phases. The concentration of Ho (III) was monitored by square wave voltammetry and analyzed by inductive coupled plasma atomic emission spectrometer (ICP-AES). The calibration curve was obtained on linear relationship of peak currents and concentration of Ho (III). Meanwhile, the extraction efficiencies were calculated by ICP-AES and calibration curve, respectively, the highest extraction efficiency could reach 95.9% by potenostatic electrolysis at -1.6 V for 27 h. [ABSTRACT FROM AUTHOR]

Electrochemical behavior of Ce(III) and underpotential deposition of Al-Ce alloys were investigated at an Al active electrode in LiCl-KCl-CeCl 3 melts. Compared with the cyclic voltammetry curves on a Mo electrode, the redox potential of Ce(III)/Ce at the Al electrode is more positive; there are two new plateaus between the deposition plateau of Al and Ce metal by open circuit chronopotentiometry, which means two kinds of intermetallic compounds. All above show Ce(III) forms intermetallic compound by underpotential deposition electrochemically. Furthermore, it is also confirmed by Al-Ce alloys, which are obtained at the Al active electrode in LiCl-KCl-CeCl 3 melts after potentiostatic deposition under the same condition. The formation of AlCe and AlCe 3 is illuminated by X-ray diffraction (XRD). The reasons of AlCe and AlCe 3 formation were explained by XRD and phase diagram of Al-Ce. The standard Gibbs free energies of AlCe and AlCe 3 formation were calculated by XRD and open circuit chronopotentiometry. The analysis of scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS) reveals that cerium exists at the surface of Al electrode to form an Al-Ce alloys layer, which is about 28 μm in thickness, and evenly coated the Al electrode. [ABSTRACT FROM AUTHOR]

Electrochemical preparation of different phases Al-Y alloys were investigated in LiCl-KCl-AlCl 3 -Y 2 O 3 melts at 773 K by cyclic voltammetry, square wave voltammetry, open circuit chronopotentiometry and polarization curve. The electrochemical measurements show that the underpotential deposition (UPD) of Y on pre-deposited Al forms two Al-Y intermetallic compounds. The results of X-ray diffraction (XRD) indicate that the two different Al-Y intermetallic compounds are Al 2 Y and α -Al 3 Y. The microstructure and the micro-zone chemical composition of Al-Y alloys were characterized by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS), respectively. The results illustrate that element Y is mainly distributed on nubby precipitates. Different phases Al-Y alloys can be obtained by adjusting the concentration of AlCl 3 . [ABSTRACT FROM AUTHOR]

This work reports the electrochemical fabrication of Mg-Ca alloys by co-deposition of Mg and Ca ions in KCl-CaCl2-MgCl2 melts at 943 K on tungsten electrodes. Cyclic voltammetry indicated that co-reduction of Mg(II) and Ca(II) ions occurs at about -2.23 V in KCl-CaCl2 eutectic melts at 943 K. The diffusion coefficient of Mg(II) in KCl-CaCl2 eutectic melts was determined by chronopotentiometry with Sand's equation. Open-circuit chronopotentiometry was applied to evaluate the equilibrium potential of Mg(II)/Mg(0) system. Bulk products of Mg-Ca alloys were obtained by galvanastatic electrolysis at 6.00 A cm"2 on tungsten electrodes. The compositions of obtained Mg-Ca alloys were analyzed by inductive coupled plasma atomic emission spectrometer (ICP-AES). X-ray diffraction (XRD) indicates that Mg-Ca alloys mainly comprise a-Mg and Mg2Ca phases. The microstructure and micro-zone chemical analysis of Mg-Ca alloys were characterized by scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS) analysis. [ABSTRACT FROM AUTHOR]

An ultrasonic-assisted method for electroless Ni-P plating on dual-phase Mg-Li alloy is proposed. Environmentally-friendly Ce(NO3)3-KMnO4 solution was successfully applied for the pre-treatment. Uniform and compact Ni-P coatings with fine structures have been successfully obtained. The Ni-P coatings are mixed with amorphous-crystalline features and well adhered to the substrates. The corrosion resistances were investigated by electrochemical impedance spectroscopy, open circuit potential, potentiodynamic polarization and hydrogen evolution tests. The results indicate that ultrasonic processing significantly improves the corrosion resistance of Ni-P coatings due to the formation of uniform, dense and fine structures, which strengthen the passive film. [ABSTRACT FROM AUTHOR]

This work presents a novel study on electrochemical preparation of Mg-Li-Yb alloys at a magnesium electrode in LiCl-KCl-YbCl3 melts at 743 K. Cyclic voltammograms showed that the reduction of ytterbium(III) ions is a stepwise reaction. The codeposition of Yb and Li takes place at magnesium electrode when the current intensity exceeds 60 mA in LiCl-KCl melts containing 2 wt % YbCl3. α, α + β, and β phases. Mg-Li-Yb alloys with different lithium contents were obtained by potentiostatic electrolysis at a magnesium electrode from LiCl-KCl melts with different concentrations YbCl3. [ABSTRACT FROM AUTHOR]