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This paper presents a new method that electrolytic separation of high-purity Sb powders from Pb-containing Sb alloy in choline chloride-ethylene glycol eutectic solvent(ChCl-EG DES). The effect of ... on the viscosity and electrical conductivity of SbCl3 + ChCl-EG DES is tested at 343 K. The results show that with the increase of ..., the viscosity of SbCl3 + ChCl-EG DES gradually increases, while the electrical conductivity is reverse. The anodic dissolution behaviors of Sb and Pb have been investigated by linear sweep voltammetry in SbCl3 + ChCl-EG DES. The results show that the oxidation potentials of Sb and Pb are both about 0 V. It is beneficial to the electrolytic separation of Pb-containing Sb alloy, when the CSbC13 increases from 0.05 mol/L to 0.25 mol/L. The results of electrolysis experiments show that agglomerated and irregular Sb powder with a purity of 99.980 % can be obtained at 343 K and 0.15 mol/L SbCl3, and the corresponding current efficiency and specific energy consumption are 93.57% and 749.18 kW · h/t, respectively. [ABSTRACT FROM AUTHOR]

During the preparation of metallic silicon by the molten salt electrolysis of SiO2, the electrolytic temperature and the gaseous pressure affect the electrochemical reduction of SiO2 significantly. According to the thermodynamic calculation, in the cathodic electro-deoxidization process, SiO2 is more easily electrolyzed to the formation of metallic Si due to the worse stability in molten salt. Otherwise, the stability of CaSiO3 is better, resulting m the more difficulty for the reduction. The increase of electrolytic temperature is good for the decrease in the Gibbs free energy and the decomposition voltage of the electrodeoxidization reactions of SiO2 and CaSiO3. The anodic gas is composed of CO and CO2 as graphite is chosen as the anode. The decomposition voltage of each reaction is decreased with the increase of the gaseous pressure, resulting in the positive process of the electrolytic reactions. [ABSTRACT FROM AUTHOR]

Abstract: The electrochemical behavior of titanium dioxide film in Lewis basic AlCl3-1-butyl-3-methylimidizolium ionic liquid (AlCl3-BMIC) at room temperature was investigated by means of potentiodynamic polarization; cyclic voltammetry; sampled current voltammetry and electrochemical impedance spectroscopy (EIS). It was found that as the TiO2 film thickness increased, a cathode inhibition effect of the oxide film on the reduction process was strengthened, which means that a greater overpotential was required to initiate the reduction process. In the EIS test, the preferable equivalent circuit was made to fit the experimental data and fitted parameters were obtained. Additionally, increasing reaction temperature can make the cathode depolarization. In the end, the model for this reduction process has been given on the basis of the pictures of reduced TiO2 film and the electronic energy band structure models. [Copyright &y& Elsevier]

Abstract: The direct electrochemical reduction of titanium dioxide (TiO2) to metallic titanium at room temperature is firstly studied in Lewis basic AlCl3–1-butyl-3-methylimidizolium (AlCl3–BMIC) ionic liquid. In this study, cyclic voltammetry, potentiodynamic polarization, sampled current voltammetry and X-ray photoelectron spectroscopy (XPS) techniques were utilized. Analysis of the cyclic voltammetry suggested that TiO2 film can be reduced to metallic Ti. The sampled current voltammetry was applied to elaborate the reduction mechanism and the results showed that this reduction process may include two steps. When the output potential difference of 2.8V was applied, a TiO2 cylindrical pellet was partly reduced to metallic Ti. However, due to the very slow reaction rate, there was only about 12wt% of TiO2 was reduced during the electrolysis time of 48h. It was predicted that the process for the direct reduction of solid TiO2 would be explained as follows: given enough cathode potential, the reduction happened at the cathode/ionic liquids interface, where the oxygen was ionized, then dissolved in the ionic liquid and discharged at the anode, with the metallic Ti left at the cathode. [Copyright &y& Elsevier]

The electrodeposition and electrochemical behaviors of rare earths in different ionic liquids are summarized. It is demonstrated that most of the rare earths can be electrodeposited in ionic liquids except cerium. Anion of ionic liquids appears to play a significant role in determining the electrochemical windows, and then deciding whether the corresponding ionic liquids can be used for rare earths electrodeposition. The electrochemical behaviors of the reduction process in ionic liquids are similar to those in high-temperature molten salts. The reduction of RE(III) to RE(II) has different reversibility, but the reaction of rare earths to their zerovalent state is irreversible. [ABSTRACT FROM AUTHOR]

The use of room-temperature ionic liquids (RTILs) as green media for electrochemical application has attracted great attention recently. However, the effects of RTILs used as additives for electrodeposition of metals have hardly been explored. In the present work, the electrochemical deposition of copper was investigated on a pure copper plate from acid cupric sulfate solutions in the presence of RTILs (1-butyl-3-methylimidazolium tetrafluoroborate, [bmim] BF4) additive by cyclic voltammetric technique, scanning electron microscope (SEM), and X-ray diffraction (XRD). For comparison, the electrodeposition of copper from acid cupric sulfate solutions was also investigated. The voltammograms showed that the cathodic peak potential shifted toward more negative potential and cathodic peak current increased when 1.0 x 10(-4) mol x L(-1) [bmim] BF4 was added into acid cupric sulfate solutions. SEM images indicated that the shinning electrodeposits of copper were lamellar structure and the size of layered grain decreased with addition of [bmim]BF4 additive. The XRD results indicated that copper deposits exhibited face-centered cubic structure and (220) highly preferred orientation. The surface-enhanced Raman scattering (SERS) activities of copper deposits were measured by using methyl orange (MO) as the probe molecules. The copper electrodeposit obtained in acid cupric sulfate solutions with [bmim]BF4 is shown to be excellent substrate for SERS measurements, demonstrating significant enhancement and good stability. The enhancement factor was calculated to be up to 4.7 x 10(5). It was also found that copper electrodeposit stored for 60 days in air shows no significant degradation in its sensitivity.

The use of room-temperature ionic liquids (RTILs) as green media for preparation of nanomaterials is very attractive. Herein, anisotropic silver nanoparticles were synthesized via chemical reduction silver nitrate with sodium hypophosphite, employing brønsted acidic functionalized ionic liquid 1-butyl-3-methyl-imidazolium dihydrogen phosphate ([bmim] H2PO4), which acted both as reaction medium and as a capping/shape-directing agent. The structure, morphology and optical absorption properties of anisotropic silver nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Visible (UV-Vis) absorption spectra. The XRD patterns revealed that the crystal was cubic structure for anisotropic silver nanoparticles. The SEM image indicated that the anisotropic silver nanoparticles were block-like with average lateral dimensions of about 30 nm, and they were self-assembled into two-dimensional disordered multilayer on the silicon wafer, and the particles appeared to be closely packed. The UV-Vis absorption spectrum exhibited a strong absorption peak around 438 nm and a weak peak at 353 nm, which came from dipole and quadrupole oscillation resonance, indicating the formation of non-spherical silver nanoparticles. The surface-enhanced Raman scattering (SERS) active of the anisotropic silver nanoparticles were investigated using trans-1,2-bis(4-pyridyl)-ethylene (BPE) as probe molecule. The results indicate that self-assembled silver film of anisotropic silver nanoparticles on the silicon wafer is excellent substrate for SERS measurements, demonstrating significant enhancement, trace detection capability, and good stability. The minimum analytic concentration was 10(-9) mol x L(-1) for trans-1,2-bis (4-pyridyl)-ethylene (BPE) molecules. It was also found that silver film stored for 90 days in air shows no significant degradation in its sensitivity.

In the present work, the electrochemical deposition of silver was investigated on a glassy carbon electrode from AgNO3 solutions in the presence of RTILs (1-butyl-3-methyl imidazolium nitrate, [bmim]NO3) additive by cyclic voltammetric technique, scanning electron microscope (SEM) and X-ray photon spectroscopy (XPS). For comparison, the electrodeposition of silver from [bmim]NO3-free AgNO3 solution was also investigated. The voltammograms showed that the cathodic peak potential shifted toward more negative potential and the cathodic peak current decreased when 5 x 10(-6) mol x L(-1) [bmim]NO3 was added into AgNO3 solutions. This indicated that [bmim]NO3 produced an inhibition of silver deposition, probably related to the adsorption of [bmim]NO3. SEM images showed that the uniform, shining electrodeposits of silver obtained in AgNO3 solutions were rather compact and that the size of silver grains decreased with the addition of [bmim]NO3 additive. The surface-enhanced Raman scattering (SERS) activities of silver deposits were measured by using methyl orange (MO) as the probe molecules. The strongly enhanced Raman scattering from the monolayer film of MO demonstrated that the as prepared silver particular film was SERS active. The enhancement factor was calculated to be up to 1.7 x 10(5) and 1.1 x 10(5) for silver film obtained in AgNO3 solutions with and without [bmim]NO3 additive, respectively.