Electrochemical Study of Indium in a Water‐Stable 1‐Ethyl‐3‐Methylimidazolium Chloride/Tetrafluoroborate Room Temperature Ionic Liquid

The electrochemistry of indium species was investigated at glassy carbon, tungsten and nickel electrodes in a basic 1‐ethyl‐3‐methylimidazolium chloride/tetrafluoroborate ionic liquid. Amperometric titration experiments suggest that In(III) chloride is complexed as [InCl₅]^2? in this ionic liquid. The electrochemical reduction of [InCl₅]^2? to indium metal is preceded by overpotential driven nucleations. The effective anodic dissolution of indium to indium(III) requires, however, the presence of sufficient chloride ions at the electrode surface. The electrodeposition of indium at glassy carbon and tungsten electrodes proceeds via three‐dimensional instantaneous nucleation with diffusion‐controlled growth of the nuclei. At the nickel electrode, the deposition proceeds via three‐dimensional progressive nucleation with diffusion‐controlled growth of the nuclei. Raising the deposition temperature decreases the average radius of the individual nuclei, r. Scanning electron microscopic and x‐ray diffraction data indicated that bulk crystalline indium electrodeposits could be prepared on nickel substrates within a temperature range between 30 and 120 °C.     

The electrodeposition of indium onto vitreous carbon from acidic chloride media

Cyclic voltammetry and potential step techniques have been used to study the electrodeposition of indium metal from 1 mol dm^?3 potassium chloride, pH 2–4.5, onto a vitreous carbon electrode. It is confirmed that the In/In³⁺ couple is fast in chloride media and the nucleation and growth of the indium phase is discussed. It is shown that instantaneous nucleation occurs at an overpotential of only a few mV and that the growth of the nuclei is three dimensional.     

Sorption kinetics of indium,iron, and zinc ions on modified montmorillonite

Adsorption integral kinetic curves of indium and iron(III) ions were obtained from model solutions on a montmorillonite Metosol modified with di(2-ethylhexyl)phosphoric acid. The adsorption kinetics can be reliably described with pseudofirst and pseudosecond order models. Adsorption of metal ions on a Metosol reagent occurs in a mixed diffusion mode. The rate constants of external and internal diffusion on the Metosol reagent are greater for In³⁺ ions than those for Fe³⁺ one, so that it can be used for the selective sorption of indium from complex technological solutions in zinc production.     

A smelting–rolling strategy for ZnIn bulk phase alloy anodes

Reversibility and stability are considered as the key indicators for Zn metal anodes in aqueous Zn-ion batteries, yet they are severely hindered by uncontrolled Zn stripping/plating and side reactions. Herein, we fabricate a bulk phase ZnIn alloy anode containing trace indium by a typical smelting–rolling process. A uniformly dispersed bulk phase of the whole Zn anode is constructed rather than only a protective layer on the surface. The Zn deposition can be regarded as instantaneous nucleation due to the adsorption of the evenly dispersed indium, and formation of the exclusion zone for further nucleation can be prevented at the same time. Owing to the bulk phase structure of ZnIn alloy, the indium not only plays a crucial role in Zn deposition, but also improves the Zn stripping. Consequently, the as-designed ZnIn alloy anode can sustain stable Zn stripping/plating for over 2500 h at 4.4 mA cm⁻² with nearly 6 times smaller voltage hysteresis than that of pure Zn. Moreover, it enables a substantially stable ZnIn//NH₄V₄O₁₀ battery with 96.44% capacity retention after 1000 cycles at 5 A g⁻¹. This method of regulating the Zn nucleation by preparing a Zn-based alloy provides a potential solution to the critical problem of Zn dendrite growth and by-product generation fundamentally.

A ZnIn alloy anode with trace indium is obtained by smelting–rolling method. The Zn deposition could be regarded as instantaneous nucleation that can alleviate the effect of deposition layer for the diffusion zone and suppresses dendrite growth.     

Selecting indium-containing systems as solid electrolytes

Quasi-binary salt systems InCl₃-MeCl₂, where Me²⁺ stands for Mg²⁺, Cd²⁺, Zn²⁺, Sn²⁺, Co²⁺, or Mn²⁺, in the region of solid solutions on the basis of InCl₃ are considered. A comparative characteristic of some transport properties of these systems is given and optimum compositions for all systems under consideration are determined. The conduction mechanism that presumably takes place in systems InCl₃-MgCl₂ and InCl₃-CdCl₂ is confirmed by data that are obtained with the aid of the Tubandt method. In order to raise the reversibility with respect to the indium ion, also considered is the In₂S₃-InCl₃ system, in which the basis compound is In₂S₃. Methods of electroconduction and XRD are used to establish the existence of a region of limited solid solutions on the basis of indium sulfide. The current efficiency in a system with solid electrolyte In₂S₃-InCl₃ is determined (CE > 50%) and the dependence of the current efficiency on the electrolysis regime is considered. Thermodynamic investigation of some indium-containing compounds and the doping with indium are conducted with use made of indium-containing solid electrolytes of optimum compositions. Data concerning the magnitude of the alteration occurring in the Gibbs energy during the formation of indium-containing semiconducting compounds, which are close to reference data, are obtained.     

Propane dehydrogenation over extra-framework In(i) in chabazite zeolites

Indium on silica, alumina and zeolite chabazite (CHA), with a range of In/Al ratios and Si/Al ratios, have been investigated to understand the effect of the support on indium speciation and its corresponding influence on propane dehydrogenation (PDH). It is found that In₂O₃ is formed on the external surface of the zeolite crystal after the addition of In(NO₃)₃ to H-CHA by incipient wetness impregnation and calcination. Upon reduction in H₂ gas (550 °C), indium displaces the proton in Brønsted acid sites (BASs), forming extra-framework In⁺ species (In-CHA). A stoichiometric ratio of 1.5 of formed H₂O to consumed H₂ during H₂ pulsed reduction experiments confirms the indium oxidation state of +1. The reduced indium is different from the indium species observed on samples of 10In/SiO₂, 10In/Al₂O₃ (i.e., 10 wt% indium) and bulk In₂O₃, in which In₂O₃ was reduced to In(0), as determined from the X-ray diffraction patterns of the product, H₂ temperature-programmed reduction (H₂-TPR) profiles, pulse reactor investigations and in situ transmission FTIR spectroscopy. The BASs in H-CHA facilitate the formation and stabilization of In⁺ cations in extra-framework positions, and prevent the deep reduction of In₂O₃ to In(0). In⁺ cations in the CHA zeolite can be oxidized with O₂ to form indium oxide species and can be reduced again with H₂ quantitatively. At comparable conversion, In-CHA shows better stability and C₃H₆ selectivity (∼85%) than In₂O₃, 10In/SiO₂ and 10In/Al₂O₃, consistent with a low C₃H₈ dehydrogenation activation energy (94.3 kJ mol⁻¹) and high C₃H₈ cracking activation energy (206 kJ mol⁻¹) in the In-CHA catalyst. A high Si/Al ratio in CHA seems beneficial for PDH by decreasing the fraction of CHA cages containing multiple In⁺ cations. Other small-pore zeolite-stabilized metal cation sites could form highly stable and selective catalysts for this and facilitate other alkane dehydrogenation reactions.

Indium-containing chabazite zeolites show better stability and C₃H₆ selectivity for propane dehydrogenation than In₂O₃, In/SiO₂ and In/Al₂O₃. Extra-framework In⁺ is identified as the stable active site upon reduction of an impregnated sample.     

Complexation Equilibria of Indium in Aqueous Chloride,Sulfate and Nitrate Solutions: An Electrochemical Investigation

Electrochemical methods have been used to determine the speciation and stability constants of various aqueous indium complexes. Qualitative behavior is observed using UV–Vis spectroscopy and cyclic voltammetry. Equilibrium constants are determined using differential pulse voltammetry. In a titration where the titrant and sample contain equal concentrations of acid and In³⁺ ions and equivalent concentrations of ligand and supporting electrolyte anions, respectively, small changes in ligand concentration can be made quickly and accurately while maintaining the overall ionic strength. From the change in the half-wave reduction potential as a function of ligand concentration, the coordination number and the stability constants of sulfate, chloride and nitrate complexes were determined. We also highlight the difficulties finding a supporting electrolyte that does not interact with the In³⁺ ion. On the one hand, it was not possible to prevent the slow formation of chloride in perchlorate electrolytes containing indium. On the other hand, we show that, at concentrations of nitrate anions commonly used in such experiments, nitrate complexes form. In the light of these new findings, previously published stability constants of indium using nitrate-based supporting electrolytes should be used cautiously.     

Electrodeposition of lead on glassy carbon and mercury film electrodes from a distillable room temperature ionic liquid,DIMCARB

The electrochemical reduction of Pb²⁺ has been studied in the ‘distillable’ ionic liquid DIMCARB (a mixture of adducts of dimethylamine and carbon dioxide, comprising both neutral and ionic moieties). Voltammetric results show that Pb²⁺ is reduced in a single step to form Pb metal via a nucleation and growth mechanism on a glassy carbon electrode. Ex situ powder X-ray diffraction studies on deposited lead show the presence of both α- and β-PbO₂, as well as elemental lead, suggesting the finely deposited lead particles are in an active rather than passive state. Chronamperometric and scanning electron microscope measurements show that the nucleation and growth follows a progressive nucleation mechanism on glassy carbon. Large peak–peak separations for the Pb reduction and oxidation are consistent with this mechanism and do not suggest electrochemical reversibility. However, experiments with co-deposition of Hg show that this irreversibility is a result of deposition onto a solid glassy carbon surface rather than a solvent effect. The diffusion coefficient of Pb²⁺ in DIMCARB has been calculated to be 1.8±0.4×10⁻⁷ cm² s⁻¹. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. This work is dedicated to Piero Zanello on the occasion of his 65th birthday in recognition of his numerous contributions to inorganic electrochemistry.     

Complex formation of indium(<Emphasis Type="SmallCaps">iii</Emphasis>) with citric acid in aqueous solution

Complex formation of In³⁺ ion with citric acid in an aqueous solution was studied by pH-metric titration at the molar ratio of the reactants [In³⁺] : [H₄Cit] = 1 : 1, 1 : 2, and 1 : 3 in a range of pH 2—10. The mathematical simulation of equilibria in an indium(iii)—citric acid system was performed using the CPESSP program package. The formation of 1 : 1, 1 : 2, and 1 : 3 indium(iii) citrate complexes with different degrees of nuclearity and protonation was established. The equilibrium constants of formation of the complexes were calculated. The predomination of the polynuclear indium(iii) citrate complexes at the equimolar metal to ligand ratio of was observed in almost the whole pH range studied (3—10).     

Chemical‐Bath‐Deposited Indium Oxide Microcubes for Solar Water Splitting

We fabricated films of cubic indium oxide (In₂O₃) by chemical bath deposition (CBD) for solar water splitting. The fabricated films were characterized by X‐ray diffraction analysis, Raman scattering, X‐ray photoelectron spectroscopy, and scanning electron microscopy, and the three‐dimensional microstructure of the In₂O₃ cubes was elucidated. The CBD deposition time was varied, to study its effect on the growth of the In₂O₃ microcubes. The optimal deposition time was determined to be 24 h, and the corresponding film exhibited a photocurrent density of 0.55 mA cm^?2. Finally, the film stability was tested by illuminating the films with light from an AM 1.5 filter with an intensity of 100 mW cm^?2.     

Indiumwolframat,In2(WO4)3 – ein In3+ leitender Festkörperelektrolyt

Indium Tungstate, In₂(WO₄)₃ – an In³⁺ Conducting Solid Electrolyte Polycrystalline In₂(WO₄)₃ has been electrochemically characterized and unambiguously identified as an In³⁺ conducting solid electrolyte. By heating, indium tungstate undergoes a phase transition between 250 °C and 260 °C transforming from a monoclinic to an orthorhombic phase for which the conduction properties have been determined. The adopted crystal structure in this high temperature region corresponds to the Sc₂(WO₄)₃ type structure. The electrical conductivity was investigated by impedance spectroscopy in the temperature range 300–700 °C and amounts to about 3.7 · 10^–5 Scm^–1 at 600 °C with a corresponding activation energy of 59.5 kJ/mol. Polarization measurements indicated an exclusive current transport by ionic charge carriers with a transference number of about 0.99. In dc electrolysis experiments, the trivalent In³⁺ cations were undoubtedly identified as mobile species. A current transport by oxide anions was not observed.     

Die neuen gemischtvalenten Chalkogenoindate MIn7X9 (M = Rb,Cs; X = S,Se): Strukturchemie,Röntgenund HRTEM‐Untersuchungen

The New Mixed Valent Chalcogenoindates MIn₇X₉ (M = Rb, Cs; X = S, Se): Structural Chemistry, X‐Ray and HRTEM Investigations Systematic X‐ray and HRTEM investigations on the ternary systems alkali metal (or thallium)–indium–chalcogen proved the existence of mixed valent solids with the simultaneous occurrence of indium species in different states of oxidation. Additionally to the earlier described solids MIn₅S₇ (M: Na, K, Tl: isotypic to InIn₅S₇ = In₆S₇ and TlIn₅S₇) and KIn₅S₆ (isotyp to TlIn₅S₆) in the actual work we present with MIn₇X₉ (M: Rb, Cs; X: S, Se) a new structure type which also contains indium in the states of oxidation +3 and +2. The formal state of oxidation In²⁺ corresponds to (In₂)⁴⁺ ions. A reasonable ionic formulation of these structures is given by: MIn₅S₇ = M⁺ 3[In³⁺] [(In₂)⁴⁺] 7[S^2–] (M = Na, K, Tl), MIn₅S₆ = M⁺ [In³⁺] 2[(In₂)⁴⁺] 6[S^2–] (M = K, Tl), MIn₇X₉ = M⁺ 3[In³⁺] 2[(In₂)⁴⁺] 9[S^2–]. The three structure types show common two dimensional structure elements which contain ethane analogous In₂X₆ units and cis and trans edge sharing double octahedron chains. The main interest of this work is a crystalchemical discussion taking into account the new compounds MIn₇X₉ and the results of special HRTEM investigations on MIn₇X₉. The HRTEM investigations aim on the identification and subsequent preparation of new phases which initially might be visible as nano size crystals or inclusions in the HRTEM only.     

The effect of some organic surfactants upon the reduction rate of In3+ in perchloric medium on mercury

The effect of Triton X-100, dodecylammonium, tetrabutylammonium, and dodecylsulphate upon the reduction rate of In³⁺ to indium amalgam in 0.1 M HClO₄ was investigated, both in the presence and in the absence of 1 M NaClO₄. After having accounted for the blocking effect upon the kinetics of In³⁺ reduction via the factor (1??), where ? is the surface coverage by the surfactant, the remaining electrostatic effect was compared with that predicted by the Frumkin theory for diffuse-layer effects. For this purpose the Gouy-Chapman-Stern theory was used to calculate the potential _d at the outer Helmholtz plane from measured values of the charge density q_M on the metal and of the charge density q_i due to the adsorbed surfactant. With the exception of Triton X-100, the electrostatic effect predicted by the Frumkin theory combined with the Gouy-Chapman-Stern theory was found to be much greater than that observed experimentally. This result was explained by the inadequacy of the Gouy-Chapman-Stern model of the double layer in the presence of bulky surface-active ions.     

Vapor pressure and dissociation energy of (In2O)

The vapor pressure of pure liquid indium, and the sum of pressures of (In) and (In₂O) species over the condensed phase mixture {In} + <In₂O₃>, contained in a silica vessel, have been measured by Knudsen effusion and Langmuir free vaporization methods in the temperatue range 600 to 950°C. Mass spectrometric studies reported in the literature show that (In) and (In₂O) are the important species in the vapor phase over the {In} + <In₂O₃ >; mixture. The vapor pressure of (In₂O) corresponding to the reaction,

deduced from the present measurements is given by the equation,

The “apparent evaporation coefficient” for the condensed phase mixture is approximately 0.8. The energy for the dissociation (In₂O) molecule into atoms calculated from the above equation is D°₀ = 180.0 (± 1.0) kcal mol^?1.     

Effect of Indium Oxide Modification on the Phase Composition,the Structure of a Hydroxyl Cover,and the Electron-Acceptor Properties of Zirconium Dioxide

The effect of modification with indium oxide on the crystal structure, hydroxyl cover, and electron-acceptor properties of zirconium dioxide was studied. It was found that complex binary systems with a highly thermally stable tetragonal ZrO₂ phase can be prepared by the modification. The concentration of In³⁺ in the lattice of ZrO₂ depends only slightly on the total concentration of In₂O₃ in the system. The major portion of the indium oxide added is localized as an individual X-ray amorphous phase in intercrystallite voids. The In₂O₃ phase formed in these systems does not cover the surface of ZrO₂ but is mainly localized in the intercrystallite space. The presence of the modifier component affects the predominant crystallographic direction and the defect structure of the surface formed. The modification was found to affect the structure of a hydroxyl cover and the electron-acceptor properties of zirconium dioxide.     

LiInSiO4: a new monovalent–trivalent olivine

The structure of the olivine LiInSiO₄ (lithium indium silicate) is isotypic with LiScSiO₄ and MgMgSiO₄ (forsterite). The main differences between the title compound and the divalent–divalent olivines are found for the bond lengths and angles opposite common edges between the tetrahedron and the Li⁺ and In³⁺ ion sites. The tetrahedron shares one common edge with the Li⁺ site and two common edges with the In³⁺ site. The tetrahedron is distinctly distorted, as are the Li⁺ and In³⁺ sites.     

The Kinetics of Indium Electroreduction from Chloride Solutions

The electroreduction of indium on indium electrode (99.98%) in perchlorate-containing chloride electrolytes is studied by the methods of linear sweep and cyclic voltammetry, impedance spectroscopy, and chronoamperometry. The indium electroreduction is limited by diffusion, the reaction rate constant is 1.3 10^–4 cm/s at the indium salt concentration of 0.1 M. The values of the apparent rate constant for the charge transfer stage found by linear sweep and cyclic voltammetry and also by impedance spectroscopy are 2.37 × 10^–3, 3.62 × 10^–3, 3.06 × 10^–3 cm/s, respectively. The values of diffusion coefficient of indium(III) ions calculated according to the Cottrell equation based on chronoamperametric measurements and from the Warburg impedance found by impedance spectroscopy are in good agreement. The presence of the Gerischer impedance is stated, which suggests that a homogeneous reaction of formation of indium chloride complexes proceeds and its mechanism is chemical-electrochemical.

     

An Indium‐Seamed Hexameric Metal–Organic Cage as an Example of a Hexameric Pyrogallol[4]arene Capsule Conjoined Exclusively by Trivalent Metal Ions

A hexameric metal–organic nanocapsule is assembled from pyrogallol[4]arene units, which are stitched together with indium ions. This indium‐seamed capsule is the first instance of a M₂₄L₆ type hexameric coordination cage held together exclusively by trivalent metal ions. Explicitly, unlike previously reported pyrogallol[4]arene‐based metal‐seamed capsules, the current In³⁺ seamed capsule is entirely supported by O→In coordinate bonds. This work demonstrates the important proof of concept of the ability of pyrogallol[4]arene to react with metals in higher oxidation states to assemble into atomically‐precise hexameric coordination cages. As such, these results open up exciting avenues toward the assembly of previously unanticipated metal–organic capsules, for example offering inspiration for tackling metals exhibiting high valence states such as in the lanthanide and actinide series.     

Separation of In3+ from Cd2+ on crystalline antimonic acid.115Cd−115mIn generator

The distribution coefficients of Cd²⁺ and In³⁺ on crystalline antimonic(V) acid (C-AA) have been determined in order to find the best conditions for separation of both cations. Very high affinity of C-AA for Cd²⁺ ions enables to separate^115mIn from¹¹⁵Cd in a single-step rapid procedure. The indium fraction obtained was very pure; the amount of radioactive contaminants was less than 0.0005%.     

Ternäre Thallium-Indium-Sulfide: Eine Zusammenfassung

Ternary Thallium Indium Sulfides: A Summary Combined thermal and X-Ray analyses in the ternary system Thallium—Indium—Sulfur show, that the two binary sections Tl₂S? In₂S₃ and TlS? InS contain ternary compounds with unique crystal structures. The chemical formulas of these ternary solids are TlIn₅S₈, TlIn₃S₅, TlInS₂ and Tl₃InS₃ for the section Tl₂S? In₂S₃ and TlIn₅S₆ as well as Tl₃In₅S₈ (metastable high temperature phase) for the section TlS? InS respectively. With TlIn₅S₇ an additional ternary solid could be detected, which is located outside the two sections. It is derived from the binary mixed valence compound In₆S₇ by complete substitution of In⁺ by Tl⁺. The following ionic formulations make the mixed valence character of the ternary Thallium—Indium-Sulfides reasonable: TlIn₅S₈ = Tl⁺(In³⁺)₅(S^2?)₈, TlIn₃S₅ = Tl⁺ (In³⁺)₃(S^2?)₅, TlInS₂ = Tl⁺In³⁺(S^2?)₂, Tl₃InS₃ = (Tl⁺)₃In³⁺ · (S^2?)₃, TlIn₅S₆ = Tl⁺([In₂]⁴⁺)₂In³⁺ (S^2?)₆, Tl₃In₅S₈ = 4 × [(Tl⁺)_0,75 · (In⁺)_0,25In³⁺(S^2?)₂], TlIn₅S₇ = Tl⁺[In₂]⁴⁺ (In³⁺)₃(S^2?)₇. All compounds contain Tl⁺-ions in a characteristic “lone pair coordination” of S^2? ions. Indium atoms however occur with the oxidation numbers +2 (formal, In₂ dumb bells with covalent In? In bonding) and +3 (with In³⁺ in tetrahedral and octahedral coordination of S^2?). Chemical preparation, crystal chemistry and general properties of the ternary solids are discussed, summarized and compared to each other.