Potentiostatic Electrolysis Research Articles

Dissolution of Rare Earth Elements from Nd Magnet Scraps Using Gas Electrodes in Molten Chlorides

Here we study the dissolution of rare earth elements from Nd magnet scraps using Cl2 or O2 gas electrodes in order to achieve new rare earth recycle process. The anodic polarization of Nd magnet scraps and cathodic polarization of O2 gas electrodes were investigated in molten LiCl-KCl systems at 723 K. The anodic polarization was carried out by potentiostatic electrolysis of Nd magnet scraps electrode from 0.69-2.39 V(vs. Li+/Li) at every 0.050 V interval. The large anodic current was observed at 1.80-2.00 V due to anodic reaction of dissolution of rare earth elements. On the other hand, the cathodic polarization was carried out by potentiostatic electrolysis of O2 gas electrode using porous Ni from 1.20-2.30 V at every 0.10 V interval in a molten LiCl-KCl added Li2O(0.50 mol%) system. The large cathodic current was observed from 1.40-1.90 V due to cathodic reaction from O2 to O2-. It was possible to dissolve rare earth elements selectively from Nd magnet scraps using O2 gas electrodes.

Electrochemical behavior and extraction of zirconium on Sn-coated W electrode in LiCl-KCl melts

To recover metallic Zr from LiCl-KCl melts, the electroreduction of Zr(IV) ion was studied employing a variety of electrochemical methods on W and Sn-coated W electrodes. Zr(IV) ion was reduced to metallic Zr through two consecutive steps on W electrode: Zr(IV) + 2e− → Zr(II) and Zr(II) + 2e− → Zr, whereas one-step four-electron transfer on Sn-coated W electrode, i.e, xSn + 4e− + Zr(IV) = SnxZr. The formation of different Sn-Zr intermetallic compounds SnxZr resulted in three reduction peaks occurring at more positive potential than that of Zr(IV) on the W electrode, which was detected using cyclic voltammetry (CV) and square wave voltammetry (SWV). Meanwhile, the thermodynamic data, such as partial molar Gibbs energy and activity of Zr in Sn-Zr alloys and standard molar Gibbs energy of formation for Sn-Zr compound, were evaluated by open circuit chronopotentiometry (OCP). Furthermore, galvanostatic electrolysis (GE) at 0.1 A and potentiostatic electrolysis (PE) at −0.85 V were performed on liquid Sn electrode, and electrolytic products were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). Experimental results indicated that metallic Zr was recovered and Sn2Zr was prepared on liquid Sn electrode in LiCl-KCl-K2ZrF6 melts.

Co-reduction behaviors of Ce (III), Al (III) and Ga (III) on a W electrode: An exploration for liquid binary Al-Ga cathode

Both Al and Ga have exhibited excellent performance, respectively, for the An/Ln separation based on molten salt electrolysis, and the Al-Ga composite cathode may have superior properties. Therefore, in this work, the electrochemical behaviors of Ce (III) on the binary Al-Ga electrode were systematically explored by co-reduction of Ce (III), Al (III) and Ga (III) on a W electrode. A new oxidation signal of Al2Ga2Ce ternary intermetallic compound was successfully detected. In addition, for comparison, the co-reduction behaviors of Ce (III) with Al (III) and Ce (III) with Ga (III) on an inert tungsten electrode were also investigated. The results showed that different kinds of alloys are formed on the surface of W electrode. Finally, several typical Ga-Ce and Al-Ga-Ce intermetallic compounds were obtained by potentiostatic electrolysis and the deposited products were characterized by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDS).

Electrodeposition of Pr-Mg-Co ternary alloy films from the choline chloride-Urea ionic liquids and their corrosion properties

This paper aims to obtain rare earth magnesium alloy with good adhesion and corrosion resistance. The work was concerned with the electrochemical behaviors of Co(II), Mg(II), Pr(III) on Pt and Cu electrodes in choline chloride-urea ionic liquids by electrochemical techniques of cyclic voltammetry. The electrodeposition conditions of Pr-Mg-Co ternary alloy films on copper substrate from the choline chloride-urea ionic liquids with different metal salts were investigated by potentiostatic electrolysis. The author has used scanning electron microscopy coupled with energy dispersive X-ray spectroscopy to study the surface morphology and composition of Pr-Mg-Co ternary alloy film, Polarization curves are tested. Results shows under −1.15 V voltage, the alloy films with evening is obtained when the concentration ratio of Pr(III)/Mg(II) is 4:3, and deposition time is 30 min .it showed that the content of Pr in the alloy film has reached up to 13.22 wt.%, and the morphology of black alloy coating is amorphous and has micro-cracks, which reflects the alloy films has good corrosion performance in alkaline solution. This can be attributed to its dense film structure and good adherence to the substrate. It provides some technology for the production of corrosion- resistant materials.

Comparative morphological and crystallographic analysis of copper powders obtained under different electrolysis conditions

Abstract Production of copper powders by the potentiostatic electrolysis under different hydrogen evolution conditions was investigated. Copper powders were characterized by the scanning electron microscope (SEM), X-ray diffraction (XRD), particle size distribution (PSD), and by the determination of the specific surface area (SSA) of the formed powders. Depending on quantity of hydrogen generated during electrolysis, the two types of particles were formed: dendrites and cauliflower-like particles. The dendrites were formed without, while cauliflower-like particles with the quantity of evolved hydrogen enough to achieve strong effect on hydrodynamic conditions in the near-electrode layer. Although macro structure of the particles was very different, they showed similar micro structure. Namely, both types of the particles consisted of small agglomerates of approximately spherical Cu grains at the micro level. The existence of the spherical morphology was just responsible for random orientation of Cu crystallites in both types of particles. The SSA of cauliflower-like particles was more than two times larger than that of the dendrites, while their size was considerably smaller than that of the dendritic particles. In this way, the useful benefit of Cu powder formation in the conditions of vigorous hydrogen evolution is shown.

Obtaining powders and coatings of various tantalum silicides by electrochemical methods

Joint electroreduction of tantalum and silicon fluoride complexes was studied by cyclic voltammetry in the (NaQ-KQ)equimol.-NaF-K2SiF6-K2TaF7 melt. The formation of tantalum silicides has been studied by cyclic voltammetry and chronopotentiometry methods. Parameters for electrochemical synthesis of tantalum silicides were found. Tantalum silicide powders were obtained by potentiostatic electrolysis at different potentials, at temperature of 1073K and duration of the process 2 hours. Tantalum silicide coatings on a silver substrate were synthesized by galvanostatic electrolysis at current densities 30–130 mA cm−2 and contact displacement method. The relationship between current density and composition of the tantalum silicide coatings was shown.

Low-temperature electrochemical codeposition of aluminum-neodymium alloy in a highly stable solvate ionic liquid

A highly stable solvate ionic liquid comprising a 2:1 (mol/mol) mixture of ethylene carbonate (EC) and AlCl3 was used for near room-temperature electrochemical codeposition of an Al-Nd alloy using chlorides as precursors. This liquid is low-cost, easy to prepare, and has high electrochemical stability. The ionic structure was analyzed by 27Al nuclear magnetic resonance; Raman spectroscopy and the dissolution phenomenon was studied by ultraviolet-visible spectroscopy. The dissolution mechanism of NdCl3 in this solvate ionic liquid was derived as 3[AlCl2(EC)n]+ + 2NdCl3 ⇆ 2Nd(III) + 3[AlCl4]− + 3nEC. Cyclic voltammetry was used to explore the electrochemical behavior of Nd- and Al-containing species, revealing that the reduction of Al and Nd are both one-step electron-gaining processes. X-ray diffraction confirmed that an Al-Nd alloy can be obtained in the form of thermally stable Al2Nd by potentiostatic electrolysis at high cathode overpotential (− 3.5 V vs. Al). Although the deposited alloy layer is not dense, Al-containing solvate ILs have immense potential in green electrometallurgy because of their higher tunability and similar properties to ILs.

Electrochemical polymerization of 4,4′-thiobis-phenol in alkaline solution and properties of polymer

The electrochemical polymerization of 4,4′-thiobis-phenol in different concentrations of alkaline media has been carried out using cyclic voltammetry. Electrochemical autocatalytic reaction of poly(4,4′-thiobis-phenol) (TDP) in a high concentration of alkaline medium was verified by potentiostatic and galvanostatic electrolysis. PolyTDP showed different electrochemical activities in solutions with different pH. The electrochemical impedance spectroscopy (EIS) was used to characterize the polyTDP. The visible and FT-IR spectra of polyTDP were also measured. Scanning electron microscopy showed that the prepared polyTDP film exhibited a dense, uniform structure, which makes it a potential material for sensor construction.

Electrochemical Co-Reduction of Ce (III) and Ga (III) and Preparation of the Intermetallic Compound in LiCl-KCl Eutectic

Molten salt as a kind of reaction media, which possesses high radiation stability and thermal stability, has been widely investigated in the nuclear field for the separation of lanthanides (Ln) and actinides (An). In this work, the electrochemical co-reduction of Ce (III) and Ga (III) on tungsten electrode at 773K was researched In LiCl-KCl-CeCl3-GaCl3 system by a series of electrochemical techniques, such as cyclic voltammetry (CV), square wave voltammetry (SWV) and open circuit chronopotentiometry (OCP). Three reduction signals were detected by CV and SWV, which showed the formation of Ga-Ce intermetallic compounds due to Ce deposited on the pre-deposited Ga film and reacted with Ga: Ga(III)+3e-=Ga and Ce(III)+3e-+xGa=CeGax. Then, Ce-Ga intermetallic compounds were prepared by potentiostatic electrolysis in LiCl-KCl-CeCl3-GaCl3 melts on molybdenum grid to establish the relationship between the composition of deposits and the equilibrium potential. The deposition products were analyzed by XRD and SEM-EDS. The results indicated two intermetallic compounds CeGa2 and CeGa6 were obtained by potentiostatic electrolysis at 0.34 V for 1.5 h. Acknowledgments The work was financially supported by the National Natural Science foundation of China (11675044, 11575047 and 21790373), the Major Research plan of the National Natural Science Foundation of China (91326113 and 91226201), and the International Exchange Program of Harbin Engineering University for Innovation−oriented Talents Cultivation.

Electrodeposition of Silicon with a Liquid Gallium Cathode in Molten Salts

Further development of solar power depends largely on the availability of inexpensive solar grade silicon. Electrodeposition is a candidate method to produce high purity silicon at a reasonable cost. We have previously studied electrodeposition of silicon from molten calcium chloride based electrolytes and molten fluoride electrolytes. Recent experiments were carried out by using a liquid gallium cathode. The approach is based on studies by Stephen Maldonado and coworkers [1] of electrodeposition of silicon by using a liquid gallium cathode in an organic based electrolyte. Silicon has a low tendency to alloy with gallium. Electrochemical studies and electrolysis to deposit silicon from molten eutectic KCl – KF with 2 mol% K2SiF6 were carried out at 650 oC. Silver wire and glassy carbon rod were used as working electrodes, while glassy carbon rod or silver wire were counter electrodes. A silicon flag reference electrode was used. Liquid gallium in a small alumina tube with tungsten lead was the cathode during electrolysis while glassy carbon or silicon was the anode. Silicon deposition is diffusion controlled on silver cathode, while silicon deposition is charge transfer controlled on liquid gallium cathode. Silicon was found to deposit using a liquid gallium cathode, both during galvanostatic and potentiostatic electrolysis. The current efficiency was found to be quite high, and consistently above 80 %. Some silicon particles were found on top of gallium after cooling down. A much larger amount of gallium was used in recent experiments. This helped to form silicon particles inside the liquid gallium cathode. Silicon was recovered after experiments by physical separation from liquid gallium followed by dissolution of gallium in concentrated HNO3. High purity silicon was obtained. Gallium can form alloys with many impurity elements which may cause a refining effect of silicon. The use of a liquid gallium cathode is promising for the prospect of developing a new process for producing high purity silicon by electrolysis in molten salts.

Electrochemical Behavior of Si(IV) on the Mo Electrode in the CaCl2–CaF2–CaO–SiO2 Melt

This work concerns a study on investigating the electrochemical behaviors of silicon using the molybdenum electrode in molten CaCl2–CaF2–CaO–SiO2 at 1023 K, by means of linear scan voltammetry, square wave voltammetry, chronoamperometry, open circuit chronopotentiometry, reversal chronopotentiometry and polarization curve. The results based on the linear scan voltammetry showed that reduction of Si(IV) in CaCl2–CaF2–CaO–SiO2 melt proceeds in a single step exchanging four electrons, which is a reversible process with diffusion-controlled mass transfer, and the diffusion coefficient for the reduction process of Si(IV) ions in CaCl2–CaF2–CaO (3.68 wt %)–SiO2 (4 wt %) is about 1.11 × 10−4 cm2 s−1, at 1023 K. The reversibility of the Si(IV)/Si redox couple on the molybdenum electrode is confirmed via linear scan voltammetry. Chronoamperometric measurements indicated that the I–t transients of Si(IV) follow instantaneous nucleation with varied the applied overpotential. Furthermore, the sample deposited on the molybdenum electrode using potentiostatic electrolysis was identified by X-ray diffraction (XRD). The XRD result indicates that the obtained deposits were Si and MoSi2.

Electrochemical Behavior and Extraction of Yttrium on Cu Electrode in LiCl-KCl Eutectic

The electrochemical behaviors of Y(III) were investigated on inert W and reactive Cu electrodes in LiCl-KCl eutectic by electrochemical technique at 773K. On an inert W electrode, the apparent standard potential of Y(III)/Y(0) couple was studied at different concentration of Y(III) ions using cyclic voltammetry. The result shows the apparent standard potential of Y(III)/Y(0) couple has a dependent on the concentration of Y(III) ions. On a reactive Cu electrode, cyclic voltammetry, stripping voltammetry and square wave voltammetry experiment results indicated that the deposition potential of Y (III) shift toward more positive values than that on W electrode because of the formation of Cu-Y intermetallic compound. Five Cu-Y intermetallic compounds, Cu6Y, Cu4Y, Cu7Y2, Cu2Y and CuY, were found to be formed by transient and steady electrochemical methods. Based on open circuit chronopotentiogram, the intermetallic compounds of Cu7Y2 is easier to form and more stable than the others because its platform is longer. Potentiostatic and galvanostatic electrolysis was conducted on Cu electrode to extract metallic yttrium. Furthermore, the cyclic voltammetry curves showed that the redox signals observed before electrolysis almost disappeared after electrolysis. In addition, the concentration of Y(III) ions in LiCl-KCl melts were detected by inductive coupled plasma atomic emission spectrometer before and after electrolysis, and the current efficiency for the electroextraction of Y was estimated. The results showed that Y(III) ions could be effectively extracted using reactive Cu electrode. Finally, the electrolysis products were characterized by scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS) and X-ray diffraction (XRD). The results showed that yttrium and copper can form Cu-Y intermetallic compounds during electrolysis and the thickness of alloy layer is about 50 mm. Acknowledgement The work was financially supported by the National Natural Science foundation of China (11675044, 11575047, 21790373, 21271054 and 21173060), the Major Research plan of the National Natural Science Foundation of China (91326113 and 91226201), and the International Exchange Program of Harbin Engineering University for Innovation−oriented Talents Cultivation. Figure 1

Electrochemical Activation of MoTe2 for the Hydrogen Evolution Reaction

Sunlight is widely distributed geographically and provides enough energy in one hour to supply the world’s energy demands for a full year. However, this form of renewable energy is intermittent; thus current renewable energy technologies must be fed in to the grid or the excess energy is otherwise wasted. Recent efforts have therefore been focused on the conversion of this excess energy into a fuel in the form of hydrogen via water electrolysis. Due to the diffuse nature of solar power, hydrogen evolution reaction (HER) electrocatalysts are typically compared at a current density of 10 mA cm- 2, which roughly equates to a 10% efficient solar-to-fuels device.1 This means electrocatalysts of extremely high surface areas are required, thus making the scarce and expensive platinum electrocatalyst an impractical choice. Layered transition metal dichalcogenides (TMDCs) can offer a viable alternative due to their high surface area of catalytically active edge and basal plane sites which offer a maximum energy output from the entire surface. Recently, semimetallic 1T’-MoTe2 has emerged as a promising electrocatalyst for the HER based on its ability to accommodate an excess of electrons, making it a prime candidate for investigating the effect of electrochemical activation of TMDCs towards the HER.2,3 With this in mind, we report a novel solid-state nanocrystalline 1T’-MoTe2 electrocatalyst which undergoes an in operando activation as the HER progresses. Continuous cyclic voltammetry under reducing potentials results in a dramatic improvement in electrocatalytic activity after only 100 cycles, thus resulting in a positive shift in overpotential from -320 mV to -178 mV at j = 10 mA cm- 2. Similarly, potentiostatic electrolysis shows a rapid increase in current density with time, while gas chromatography confirms the continuous increase in rate of hydrogen production. This catalytic enhancement is also corroborated by a substantial improvement in turnover frequency and charge transfer resistance, all the while maintaining the original particle morphology, surface area and composition. Previous speculations attribute this improved performance in similar TMDC materials to substantial changes in crystal structure, morphology and / or composition, but the true mechanism of activation remains unclear.4–6 In this context, we aim to understand the origin of this enhanced catalytic activity, and hence investigate the stability of the nanocrystalline 1T’-MoTe2 after electrochemical activation. Further, we rule out changes in crystal structure by Powder X-Ray Diffraction and Raman Spectroscopy, while HRTEM and ICP-OES exclude changes in morphology and composition as the reason for the improved catalytic activity. Finally, by proving the electrochemically active surface area remains constant after cycling, while at the same time the charge transfer resistance halves in value and turnover frequency increases, we propose that the in operando activation is a result of changes to the electronic structure upon cycling. Hence, this study offers a new perspective on the path of electrochemical activation of TMDCs towards the hydrogen evolution reaction. References Roger, I., Shipman, M. A. & Symes, M. D. Earth-abundant catalysts for electrochemical and photoelectrochemical water splitting. Nat. Rev. Chem. 1, 3 (2017).McGlynn, J. C. et al. Molybdenum Ditelluride Rendered into an Efficient and Stable Electrocatalyst for the Hydrogen Evolution Reaction by Polymorphic Control. Energy Technol. 6, 345–350 (2018).Seok, J. et al. Active hydrogen evolution through lattice distortion in metallic MoTe 2. 2D Mater. 4, 25061 (2017).Liu, Y. et al. Self-optimizing, highly surface-active layered metal dichalcogenide catalysts for hydrogen evolution. Nat. Energy (2017). doi:10.1038/nenergy.2017.127Voiry, D. et al. Conducting MoS2 Nanosheets as Catalysts for Hydrogen Evolution Reaction. Nano Lett. 13, 6222–6227 (2013).Roger, I. et al. The direct hydrothermal deposition of cobalt-doped MoS2 onto fluorine-doped SnO2 substrates for catalysis of the electrochemical hydrogen evolution reaction. J. Mater. Chem. A 5, 1472–1480 (2017). Figure 1

Cathodic process of aluminum deposition in NaF-AlF3-Al2O3 melts with low cryolite ratio

In the present study, theoretical analysis and electrolysis testing in the laboratory scale demonstrated the potential of Al metal production by electrolysis in a NaF-AlF3-Al2O3 melt with a cryolite ratio (CR; molar ratio of NaF/AlF3) of 1.3. Subsequently, the electrochemical processes of Al deposition on a tungsten cathode in this melt at 860 °C were comprehensively evaluated by cyclic voltammetry, potentiodynamic cathodic polarization, square wave voltammetry, chronopotentiometry, and potentiostatic electrolysis. The results revealed Al deposition on the tungsten cathode, first as an Al4W alloy at approximately − 0.14 V (vs W), and then as liquid metallic Al-containing a co-deposition of metallic Na at − 0.94 V (vs W). The reduction of Al4W alloy and the deposition of metallic Al were both diffusion-controlled and quasi-reversible. The diffusion coefficient of the Al(Ш) ions was calculated to be 1.77 × 10−8 cm2 s−1. The square wave voltammetry curves indicated that the process of AlF4− ion reduction involved both a three-electron transfer reaction resulting in Al deposition (AlF4− → Al), and a two-electron transfer reaction resulting in the formation of monovalent aluminum ions AlF2− (AlF4− → AlF2−). The chronopotentiometry results revealed that the critical cathodic current for Al deposition was approximately 150 mA. X-ray diffraction (XRD) measurements and scanning electron microscope (SEM) observations confirmed that Al4W alloy and metallic Al existed on the electrode surface after potentiostatic electrolysis.

Electrochemical Synthesis and Thermodynamic Properties of Pr‐Ni Intermetallic Compounds in a LiCl‐KCl‐NiCl2‐PrCl3 Melt

AbstractIn this report, the electrochemical behaviors of Pr(III) and Ni(II) ions on a W electrode were investigated in LiCl‐KCl eutectic by cyclic voltammetry (CV), square wave voltammetry (SWV), chronopotentiometry (CP) and open‐circuit chronopotentiometry (OCP) techniques. From the results of electrochemical methods, different signals corresponding to seven kinds of intermetallic compounds in the phase diagram of Pr−Ni were observed. The thermodynamic properties of intermetallic compounds in the temperature range of 823–923 K were investigated by open‐circuit chronopotentiometry. With the evaluated apparent standard potentials of Pr−Ni intermetallic compounds, the Gibbs energies, enthalpies and entropies of formation were also calculated. The co‐reduction products by galvanostatic and potentiostatic electrolysis were characterized based on X‐ray diffraction (XRD) and scanning electron microscopy (SEM) coupled with energy dispersive X‐ray spectroscopy (EDS). The shape of the alloy obviously changes from granular to bulk, and the alloy phase changes from Pr‐rich to Ni‐rich. The co‐reduction products of PrNi5, PrNi2 and PrNi were identified.

Investigation of Molten Salt Chemical Cell Using Nd Magnet Scraps and Gas Electrodes in Molten Chlorides

Here we study the molten salt chemical cell using Nd magnet scraps and Cl2 or O2 gas electrodes in order to achieve new rare earth recycle process. The anodic polarization of Nd magnet scraps and cathodic polarization of O2 gas electrodes were investigated in molten LiCl-KCl systems at 723 K. The anodic polarization was carried out by potentiostatic electrolysis of Nd magnet scraps electrode from 0.69-2.39 V(vs. Li+/Li) at every 0.050 V interval. The large anodic current was observed at 1.80-2.00 V due to anodic reaction of dissolution of rare earth elements. On the other hand, the cathodic polarization was carried out by potentiostatic electrolysis of O2 gas electrode using porous Ni from 1.20-2.30 V at every 0.10 V interval in a molten LiCl-KCl added Li2O(0.50 mol%) system. The large cathodic current was observed from 1.40-1.90 V due to cathodic reaction from O2 to O2-.

Electrochemical Acetylcholinesterase Biosensor Based on Polylactide–Nanosilver Composite for the Determination of Anti-dementia Drugs

A new acetylcholinesterase biosensor has been developed for the determination of anticholinesterase drugs applied for neurodegenerative disease treatment. For this purpose, silver nanosendrites were deposited by potentiostatic electrolysis on a glassy carbon electrode covered with oligolactides cross-linked with p-tert-butylthiacliax[4]arene core in the cone, partial cone, and 1,3-alternate configurations. The roles of macrocycle configuration and electrolysis conditions on the silver depostion were characterized and optimal conditions selected for the subsequent immobilization of acetylcholinesterase. Silver nanoparticles provide higher response at low working potential (0.05 V) due to the electrostatic accumulation of silver ions and prevention of their leaching after reoxidation. The biosensor allows the determination of 10−12 – 10−7 M donepezil, berberine, and huperzine A within 20-30 s by the relative decay of the current related to the oxidation of thiocholine formed in enzymatic reaction. The reversible inhibition of immobilized acetylcholinesterase with huperzine A was quantified for the first time. The developed biosensor was employed for the analysis of spiked urine samples.

Extraction of neodymium from other fission products by co‐reduction of Sn and Nd

High temperature processing is an important method for recovering long‐lived elements from spent nuclear fuel. Electrolysis is the key technology for high temperature processing. The electrochemical behaviors of Sn2+, Nd3+ and the mechanisms of Sn‐Nd alloy formation were investigated on a Mo electrode at 873 K by conducting a series of electrochemical techniques. The results showed the deposition of Nd on inert electrode is a two‐step process in LiCl‐KCl‐SnCl2 (2.0 wt.%) melt system. Subsequently, the electrochemical extraction of Nd from molten chlorides were carried out on the Mo electrode at temperature of 873 K by the potentiostatic electrolysis at −1.2 V for 40 hr. Besides, the extraction efficiency is 97.6%. A series of potentiostatic electrolysis were carried out at potential range between −1.0 and − 1.4 V. The NdSn3 alloy was obtained by electrolysis at −1.2 V. This deposition potential is consistent with the predicted results of the mathematical model. The micro‐chemical analysis and morphology analysis of the deposits was characterized by energy dispersive spectrometry (EDS) with scanning electron microscopy (SEM) equipped. The composition of the deposits was analyzed by X‐ray diffraction (XRD) and inductive coupled plasma atomic emission spectrometer (ICP‐AES).

The oxidation of UF4 in FLiNaK melt and its electrolysis

The oxidation of UF4 in LiF–NaF–KF (FLiNaK) melt with oxygen sparging was conducted at 823 K and analyzed by in situ infrared spectrometer, UV–Vis absorption spectrometer, and other characterizations with thermodynamic calculations, indicating UF4 was converted to UO2F2 with the following reaction mechanism: 2UF4 (l) + O2(g) + 2H2O(g) = 2UO2F2(l) + 4HF(g). Cyclic voltammetry measurements showed that the reduction of UO22+ in oxidized melt exhibited two steps both with one exchanged electron: UO22+ + e− → UO2+ and UO2+ + e− → UO2. By potentiostatic electrolysis, the product of UO2 was obtained with nanoscale triangular sheet structure.

Interfacial phenomena associated with Li electrodeposition on liquid Ga substrates in propylene carbonate

Li electrodeposition on liquid Ga substrates was carried out in PC-LiClO4 at 40 °C. It was found that interfacial flow phenomena were induced by differences in interfacial tension between the liquid Ga and the liquid Ga-Li alloy formed on the substrate under potentiostatic electrolysis at −1.0 V (vs. Li+/Li), which caused the interfacial shape change of the liquid Ga electrode. We carried out in-situ observations in order to understand why such interfacial phenomena occur between the liquid electrolyte and the liquid metal cathode. Moreover, a significant difference in electrochemical response between liquid and solid Ga substrates was also noticed employing the current-time transient technique. These experimental results suggest that the process of liquid Ga-Li phase formation by the dissolution of electrodeposited Li atoms into the liquid Ga substrate dominated during the initial stage of Li electrodeposition. In contrast, the typical peaks induced by growth of solid Ga-Li alloy phase and Li metal phase were observed on solid Ga substrates. These results provide new insight into the design of electrochemical processing involving liquid electrolyte/liquid metal interface.