Codeposition of copper and tin from acid sulphate solutions containing polyether sintanol DS-10 and micromolar amounts of halides

Cu(II) and Sn(II) reduction in acid sulphate solutions containing polyether laprol DS-10 was investigated using voltammetric XPS and XRD techniques. Bright yellow bronze coatings can be deposited at potentials (E) that are positive than equilibrium potential () of Sn|Sn²⁺ electrode. Here, Sn(II) reduction might be treated as underpotential deposition (UPD) of tin on foreign (copper) substrate. Further incorporation of tin into integral Cu-Sn crystallic lattice yields the mixture of pure copper, α-CuSn phase and intermediate hexagonal hcp phase. The formation of free tin phase occurs at . This gives rise for strong inhibitive adsorption of sintanol that manifests itself in the development of deep voltammetric minimum.Addition of halides results in the shift of codeposition potential to more negative values and in the increase of copper content in the coatings deposited in the UPD region. The action of halides intensifies in the sequence Cl⁻ < Br⁻ < I⁻. If iodide concentration exceeds 2-3 μM, deposition of yellow bronze becomes impossible.     

Electrochemical study of the activating solution for electroless plating of polymers

This paper presents an electrochemical study about the activating solutions of the electroless plating of polymers, containing Pd(II), Sn(II) and Sn(IV) mixtures in HCl as main components. The objective of the study is the voltammetric characterization of these solutions by cyclic and linear voltammetry in order to study the recovery of tin and palladium from these solutions. The effect of concentration and rotation rate on the current−potential curves was studied using the RDE technique. The electrochemical behaviour of solutions prepared in the laboratory was performed as a prior step to the further study of real activating rinsing solutions. The electrochemical reduction of Pd(II) takes place in two one-electron transfer steps which are mass transport controlled. The electrochemical reduction of Sn(II) and Sn(IV) is also mass transport controlled and takes place with direct formation of metallic tin, although the electrochemical reduction of Sn(IV) only takes place in solutions with HCl concentrations higher than 1 M. The presence of additives in the real solutions prevent the chemical reduction of Pd(II) and the formation of Sn(IV) hydroxylated complexes. This causes the appearance of well defined diffusion waves attributable to the electrochemical reduction of Pd(II) and Sn(IV). Hence, the recovery of both species simultaneously as well as separately could be carried out, if appropriate conditions are selected.     

Effects of additives on the electrodeposition of tin from an acidic Sn(II) bath

Additive effects of formaldehyde, propionaldehyde and benzaldehyde on the deposition of tin in acidic solution of tin(II) sulfate have been investigated. The effects of these additives on cathodic polarization and a.c. impedance was measured by galvanostatic or potentiostatic methods, respectively. The reduction products of the aldehyde during the deposition and the diffusion coefficient of Sn(II) in various solutions were also determined.     

Use of cascade reduction potential for selective precipitation of Au,Cu, and Pb in hydrochloric acid solution

Optimization of reduction potential for electroseparation was studied for the recovery of gold, copper, and lead from acidic solution. A linear sweep voltammetric method enabled us to determine characteristic reduction potentials for each metal and the kinetics of the metal deposition indicated by current-voltage curves. In order to precipitate the metal species sequentially, reduction potentials were examined for the individual and mixed solutions of Au(III), Cu(II), and Pb(II). The three metals were reasonably well isolated from the mixed solutions such as Cu(II)/ Pb(II) and Au(III)/Cu(II)/Pb(II) in the order of the corresponding reduction potentials, in particular, the mass transfer controlled reduction potentials, obtained from linear sweep voltammetry (LSV) measurement.     

Electrochemical performance of Sn film reinforced by Cu nanowire

Sn/Cu nanowire composite film was electrodeposited on copper foil substrates and used as an anode material for lithium-ion batteries. The structure of the obtained composite film anode was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The electrochemical performance was evaluated by cyclic voltammetry, galvanostatic cycling and impedance spectroscopy. It was found that the Sn/Cu nanowire composite film anode showed a better cycle stability than Sn film anode, whereas the Sn/CNT composite film anode indicated poor capacity retention. It could be deduced that copper nanowire reinforced the Sn film anode due to the better wetting property of Sn on the surface of copper and reduced the loss of electric contact among tin particles in the Sn/Cu nanowire composite film anode.     

Zn–Sn electrodeposition from deep eutectic solvents containing EDTA,HEDTA, and Idranal VII

The use of deep eutectic solvents for metal electrodeposition has become an area of interest in the recent years. In this study, ethaline, propeline, and reline were used as solvents for the electrodeposition of Sn–Zn alloys. Ethaline, propeline, and reline displayed identical voltammetric profiles for the reduction of Zn(II) and Sn(II). Further studies were carried out in ethaline which is the liquid with lowest viscosity. To improve physical and morphological properties of the Sn–Zn deposits, additives were added to the ionic liquid solution. In this study, the addition of three chelators (EDTA, HEDTA, and Idranal VII) and their effects on the voltammetric behavior of zinc and tin and the resultant morphology was described. The structure and composition of the Zn–Sn deposit was largely affected by the additives with the largest effect being obtained in the presence of Idranal VII.     

Surface morphology and crystal orientation of electrodeposited tin from acid stannous sulphate solutions containing various additives

The changes in surface morphology and crystal orientation of electrodeposited tin from acid stannous sulphate solutions containing 1 mm N,N-bis(tetraoxyethylene)octadecylamine (TOGA) and various concentration (0.2–2 mm) of benzalacetone (BA) have been studied as functions of electrolysis time or BA concentration by electrochemical methods, scanning electron microscopy and X-ray diffractometry. The inhibitory effect on the reduction of the tin (II) ion became stronger with increasing concentration of BA. In the presence of both TOOA and BA, when electrolyses were carried out at the more negative potentials than the reduction potential of BA, the reduction product of BA induced reticular crystals (network structure) of tin over the whole surface. This structure appeared in the early stage of electrolysis and exhibited an intense (200) diffraction peak. On the other hand, the crystal grain size and the surface roughness of electrodeposited tin became smaller with increasing concentration of BA from 0.2 to 2 mm. Further, fine-grained and smooth electrodeposits of tin were obtained from acid stannous sulphate solutions containing TOOA and high concentration of BA due to the synergistic effect of these adsorbed species.     

XRD studies of the phase composition of the electrodeposited copper-rich Cu-Sn alloys

Studies of the phase and chemical compositions as well as of the surface morphology of Cu-Sn alloys electrodeposited in the sulphate solution containing laprol were carried out using the XRD, SEM, and EDX techniques. The multiphase composition—pure copper, the α-CuSn phase and the intermediate hcp phase were determined to be present in the deposits obtained at cathode potentials positive to that of the reversible of the Sn/Sn²⁺electrode. When the content of Sn in the deposit was higher than 12-13 at.%, the β and/or δ phases were determined to be present along with that mentioned above. The deposit obtained at the potentials negative to that of the reversible of the Sn/Sn²⁺ electrode presented the δ phase with low quantities of the pure Cu and α-CuSn phases. The grain size of deposits increased with the cathode potential until it was positive to that of the reversible of the Sn/Sn²⁺ electrode. The presence of Br⁻ ions in the solution hindered the granular electrocrystallization and reduced the Sn proportion in the alloy. It was assumed that underpotential deposition (UPD) of Sn on copper could be responsible for the formation of the multiphase composition and the intermediate hcp phase. It was concluded that the brightness of the studied Cu-Sn coatings was conditioned by the surface morphology.     

CZTSe solar cells prepared by electrodeposition of Cu/Sn/Zn stack layer followed by selenization at low Se pressure

Cu₂ZnSnSe₄ (CZTSe) thin films are prepared by the electrodeposition of stack copper/tin/zinc (Cu/Sn/Zn) precursors, followed by selenization with a tin source at a substrate temperature of 530°C. Three selenization processes were performed herein to study the effects of the source of tin on the quality of CZTSe thin films that are formed at low Se pressure. Much elemental Sn is lost from CZTSe thin films during selenization without a source of tin. The loss of Sn from CZTSe thin films in selenization was suppressed herein using a tin source at 400°C (A2) or 530°C (A3). A copper-poor and zinc-rich CZTSe absorber layer with Cu/Sn, Zn/Sn, Cu/(Zn + Sn), and Zn/(Cu + Zn + Sn) with metallic element ratios of 1.86, 1.24, 0.83, and 0.3, respectively, was obtained in a selenization with a tin source at 530°C. The crystallized CZTSe thin film exhibited an increasingly (112)-preferred orientation at higher tin selenide (SnSe _x ) partial pressure. The lack of any obvious Mo-Se phase-related diffraction peaks in the X-ray diffraction (XRD) diffraction patterns may have arisen from the low Se pressure in the selenization processes. The scanning electron microscope (SEM) images reveal a compact surface morphology and a moderate grain size. CZTSe solar cells with an efficiency of 4.81% were produced by the low-cost fabrication process that is elucidated herein.     

The underpotential deposition of Sn on Pt in acid media. Cyclic voltammetric and electrochemical quartz crystal microbalance studies

This work describes the studies of tin underpotential deposition on Pt electrodes in acid media by using cyclic voltammetry and electrochemical quartz crystal microbalance techniques. The voltammetric results were analyzed and it was verified the same values of anodic charge densities for the Sn in the solutions of perchloric acid with tin sulfate or chloride. The charge density value found (380 μC cm⁻²), in the potential region from 0.4 to 0.8 V, was attributed to the oxidation of Sn to Sn⁴⁺ (0.9 monolayer). The electrochemical quartz crystal microbalance results showed a mass-charge ratio of 16 g mol⁻¹ (43 ng cm⁻²) and 8 g mol⁻¹ (50 ng cm⁻²) in the same potential region for tin oxidation in different electrolyte solutions. These relationships are due to the formation of Sn(OH)₄ and SnO₂, respectively. The differences observed in relation to the formation of Sn(OH)₄ in solutions containing SnSO₄ and SnCl₂ were due to the presence of HSO₄⁻ in these solutions. In this manner the OH^- can adsorb on Sn in perchloric acid media with SnSO₄. The tin hydroxide and oxide are reduced in the scanning to the potentials between 1.55 and 0.05 V.     

An Electrochemical study of the formation of Benzotriazole surface films on Copper, Zinc and a Copper–Zinc alloy

The electrochemical behaviour of Cu, Cu–37Zn and Zn in benzotriazole (BTA) containing chloride solutions was studied and compared using potentiodynamic, cyclic voltammetry and electrochemical impedance spectroscopy. The presence of BTA in the chloride-containing solutions gave rise to higher breakdown potentials, significantly higher polarisation resistances and inhibited the formation of CuCl₂ and zinc-containing corrosion products. These effects were observed for pure Cu, Cu–Zn and to a somewhat lesser extent pure Zn. The electrochemical impedance data were consistent with the formation of a polymeric BTA-containing layer for all three systems.     

Production of nanoparticles of copper compounds by anodic dissolution of copper in organic solvents

The anodic behaviour of copper was investigated in ethanol solution containing LiClO₄, LiCl electrolyte and water. The type of electrolyte and the water content influences the mechanism of the anodic process and the formation of anodic products. In LiClO₄ electrolyte the dissolution of copper is related to the oxidation of Cu(I) to Cu(II). In solutions of LiCl the etching of copper begins with the creation of soluble complexes of Cu(I) with chloride ions and solvent molecules. At potentials above 0.4 V the formation of alkoxides was observed in both solutions, characterized by a yellow tint. On the other hand, above 0.8 V (i.e. above the equilibrium potential of alcohol oxidation) copper dissolution is accompanied by the formation of a blue colloidal suspension of Cu (II) copper salt. Anodic etching of copper in solutions containing 3% H₂O at potentials higher than 0.4 V leads to the formation of colloidal suspension of copper oxide nanoparticles.     

The triangular potential sweep voltammetric studies on pure tin in concentrated sodium hydroxide solutions

The triangular potential sweep voltammetric studies were carried out on pure tin (99.9999%) in NaOH solutions (1–10 N). The forward scan revealed two distinguished peaks in the region ?1.12 to ?0.9 V vs sce and at faster sweep rates a single peak appeared. Oscillations were observed in the E-i curve in the potential regions of Sn/Sn(OH)₂ or Sn(OH)₂/Sn(OH)₄ in the forward scan; and increase of stannite concentration increased the oscillations. The non-stoichiometric nature of the passive oxide film is responsible for these oscillations. The first anodic peak potential and current dependencies on sweep rates revealed that a “pore resistance model” holds good. The appearance of a single cathodic peak at far negative potentials, compared to the anodic peak observed at higher sweep rate, was understood to be due to irreversible reduction of oxidised species formed on the forward scan. The fractional dependence of cathodic peak current and potential on stannite ion concentration, at constant OH^? ion concentration and a Tafel slope of 60 mV decade^?1, suggests the reduction of stannite involves activated adsorption of Sn(OH) obeying the Temkin isotherm with its discharge as a rate-determining step.     

Correlation of electrochemical and ellipsometric data in relation to the kinetics and mechanism of Cu2O electroformation in alkaline solutions

The kinetics of copper anodization were studied in the potential range of Cu₂O electroformation in different alkaline solutions by using voltammetric, rotating disc electrode, rotating ring-disc electrode and ellipsometric techniques. Thin layer and massive copper electrodes were employed. Results indicate the formation of soluble Cu(I) species at the early stage of copper anodization. Other soluble Cu(II) species are produced after the Cu₂O layer electroformation. Data are discussed on the basis of a reaction mechanism involving different reaction products and the influence of the copper surface on the initial electrochemical reaction.     

Charge-discharge characteristics of a layered-structure electroplated Cu/Sn anode for Li-ion batteries

An electroplated copper/tin (Cu/Sn) anode with a layered structure is described that minimizes the high-voltage irreversible capacity observed in an electroplated Sn anode at a potential over 1 V. The high-voltage irreversible capacity is caused by the electrolyte decomposition at the catalytic site of the Sn anode. In the electroplated Cu/Sn anode, the upper Cu layer effectively suppresses the exposure of the newly formed Sn surfaces, resulting in the absence of the high-voltage irreversible capacity. Therefore, the electroplated Cu/Sn anode exhibits a higher cycle performance than the electroplated Sn anode.     

Electrodeposition of Sn-Cu alloy anodes for lithium batteries

Electrodeposition and heat-treatment was attempted to directly obtain a Sn-Cu alloy anode with fine grain of crystals for lithium ion batteries. The preparation of Sn-Cu alloy anode started with pulsed electrochemically depositing tin on the substrate of copper foil collector, and a protection coating layer of copper was plated on the surface of deposited Sn. An alloy of tin and copper was formed when heated. The energy dispersive spectroscope (EDS) and X-ray diffraction (XRD) analysis showed the copper and tin were partially alloyed to form Cu₆Sn₅ and Cu₃Sn after annealing. The SEM analysis showed the uncoated electrode is cracked after a cycle and the copper coated electrode was not cracked after 50 cycles. The Cu-coated electrode presented the first cycle coulomb efficiency reaching 95% and good cycleability.     

Corrosion and passivity of copper in solutions containing sodium sulphide. Analysis of potentiostatic current transients

The electrochemical behaviour of copper electrodes in NaOH solutions with the addition of Na₂S was studied through the analysis of current transients under constant potential and complementary voltammetric and scanning electron microscopy data including energy dispersive X-ray analysis.The overall process can be described by the following three stages. The first stage corresponds to the nucleation and growth of a complex copper sulphide layer at potential values close to the equilibrium potentials of the Cu/Cu₂S and Cu/CuS reversible electrodes. The second stage is related to the rupture of the copper sulphide film at potentials more positive than a certain critical value leading to pitting corrosion of copper metal and yielding a poorly protective copper sulphide layer. The third stage occurs in the copper oxide electroformation range, where the presence of copper sulphide accelerates the electrodissolution of the base metal and copper oxide hinders the sulphidization processes. The current transients of each stage are interpreted through a model based on the nucleation and growth mechanism.     

Recovery and Concentration of Metal Ions. II Multimembrane Hybrid System

Abstract

The multimembrane hybrid system (MHS) has been developed and used for the transportation and separation of divalent metal ions from multicomponent solutions. The system consists of three membranes in series

ion-exchange membrane | liquid membrane | ion-exchange membrane

The experiments were performed with liquid membranes composed of di(2-ethylhexyl)phosphoric acid in kerosene and Nafion-120 perfluorosulfonic acid polymer membranes. The fluxes and separation characteristics have been determined for MHS separating a solution of Zn(II), Mn(II), Cu(II), and Ni(II) sulfates as the feed phase, and the strip phase containing sulfuric acid. The results of competitive permeation experiments have shown the selectivity order Zn(II) > Mn(II) > Cu(II) ? Co(II), Ni(II). High separation coefficients were found for Zn(II), Cu(II), and Mn(II) compared to Ni(II) and Co(II).     

Study of the electrochemical deposition of Sn-Ag-Cu alloy by cyclic voltammetry and chronoamperometry

The electrochemical deposition of Sn-Ag-Cu alloy from weakly acidic baths onto glassy carbon electrodes (GCE) was studied by cyclic voltammetry (CV) and chronoamperometry (CA). The properties of the electrodeposits were characterized by scanning electron microscopy (SEM), energy-dispersive spectrometery (EDS) and X-ray diffraction (XRD). Test results indicate that the two cathodic peaks in the CV curves, at −0.6 V and −0.85 V during the forward scan towards the negative potentials, correspond to the irreversible deposition of a solid solution of tin, silver and copper. The underpotential deposition (UPD) of Sn occurs at −0.6 V during the cathodic period and the amount of Ag and Cu in the Sn-Ag-Cu alloy decreases with increasingly negative cathodic potentials. During the forward scan, towards the positive potentials used in CV testing, cathodic peaks at −0.85 V appear in the CV curves for baths containing mixtures of tin salts and triethanolamine (TEA). This corresponds to a reduction of transient complex ions [Sn(TEA)_x]²⁺ on the surface of the cathode. Furthermore, the formation and reduction of [Sn(TEA)_x]²⁺ is a diffusion controlled process. On the surface of the GCE, the actual nucleus growth mechanism of the Sn-Ag-Cu alloy is represented by the progressive nucleation model.     

In situ electrical resistance and X‐ray tomography study of copper–tin polymer composites during thermal annealing

In situ electrical conductivity and X‐ray tomography experiments are conducted on a conductive polymer composite containing polyvinylidene fluoride (PVDF) copolymer, copper (Cu), and tin (Sn) during thermal annealing. During annealing, the electrical resistivity drops by an order of magnitude, while X‐ray tomography, electron microscopy, and spectroscopy results show increasingly homogeneous dispersion of Sn in the conductive filler network, accompanied by the formation of Cu–Sn intermetallic around Cu and Sn particles. This study provides detailed insight into the morphological origins of the beneficial effect of thermal annealing on the electrical properties of conductive composites containing low melting metal fillers. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45399.