Double layer effects on metal nucleation in deep eutectic solvents

The electrodeposition of zinc has been studied in two deep eutectic solvents. Unlike the metals studied to date in these liquids, zinc electrodeposition is not mass transport limited and the morphology of the deposit differs in the two liquids. This study shows that changing the concentration of solute affects the physical properties of the liquid to different extents although this is found to not effect the morphology of the metal deposited. EXAFS was used to show that the speciation of zinc was the same in both liquids. Double layer capacitance studies showed differences between the two liquids and these are proposed to be due to the adsorption of a species on the electrode which is thought to be chloride. The differences in zinc morphology is attributed to blocking of certain crystal faces leading to deposition of small platelet shaped crystals in the glycol based liquid.     

On the electrodeposition of titanium in ionic liquids

The ability to electrodeposit titanium at low temperatures would be an important breakthrough for making corrosion resistant layers on a variety of technically important materials. Ionic liquids have often been considered as suitable solvents for the electrodeposition of titanium. In the present paper we have extensively investigated whether titanium can be electrodeposited from its halides (TiCl(4), TiF(4), TiI(4)) in different ionic liquids, namely1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([EMIm]Tf(2)N), 1-butyl-1-methylpyrrolidinium bis(trifluoromethyl-sulfonyl)amide ([BMP]Tf(2)N), and trihexyltetradecyl-phosphonium bis(trifluoromethylsulfonyl)amide ([P(14,6,6,6)]Tf(2)N). Cyclic voltammetry and EQCM measurements show that, instead of elemental Ti, only non-stoichiometric halides are formed, for example with average stoichiometries of TiCl(0.2), TiCl(0.5) and TiCl(1.1). In situ STM measurements show that-in the best case-an ultrathin layer of Ti or TiCl(x) with thickness below 1 nm can be obtained. In addition, results from both electrochemical and chemical reduction experiments of TiCl(4) in a number of these ionic liquids support the formation of insoluble titanium cation-chloride complex species often involving the solvent. Solubility studies suggest that TiCl(3) and, particularly, TiCl(2) have very limited solubility in these Tf(2)N based ionic liquids. Therefore it does not appear possible to reduce Ti(4+) completely to the metal in the presence of chloride. Successful deposition processing for titanium in ionic liquids will require different maybe tailor-made titanium precursors that avoid these problems.     

Electrodeposition in Ionic Liquids

Due to their attractive physico‐chemical properties, ionic liquids (ILs) are increasingly used as deposition electrolytes. This review summarizes recent advances in electrodeposition in ILs and focuses on its similarities and differences with that in aqueous solutions. The electrodeposition in ILs is divided into direct and template‐assisted deposition. We detail the direct deposition of metals, alloys and semiconductors in five types of ILs, including halometallate ILs, air‐ and water‐stable ILs, deep eutectic solvents (DESs), ILs with metal‐containing cations, and protic ILs. Template‐assisted deposition of nanostructures and macroporous structures in ILs is also presented. The effects of modulating factors such as deposition conditions (current density, current density mode, deposition time, temperature) and electrolyte components (cation, anion, metal salts, additives, water content) on the morphology, compositions, microstructures and properties of the prepared materials are highlighted.     

基于氯化胆碱离子液体的铜电沉积研究（英文）

采用恒电流和恒电位方法,基于含有氯化铜溶液的乙二醇-氯化胆碱或硫脲-氯化胆碱离子液体,室温下在钢阴极上进行了铜的电沉积. 利用扫描电子显微镜和X-射线衍射技术研究了各种实验条件对电沉积的影响以及沉积层的形貌. 结果表明,室温下施加不超过-0.45 V的沉积电位和不超过-4.0 A·m^-2的沉积电流密度,可以同时从氯化胆碱基乙二醇和硫脲离子液体中沉积得到非常光滑、有光泽、致密且具有良好结合力、色泽鲜艳的铜金属涂层. 铜的电沉积阴极电流效率约为97%.     

High current density electrodeposition from silver complex ionic liquids

Liquid metal salts are electrolytes with the highest possible metal concentration for electrodeposition, because the metal ion is an integral part of the solvent. This paper introduces the new ionic silver complexes [Ag(MeCN)(4)](2)[Ag(Tf(2)N)(3)], [Ag(MeCN)][Tf(2)N] and [Ag(EtIm)(2)][Tf(2)N], where MeCN stands for acetonitrile, EtIm for 1-ethylimidazole and Tf(2)N is bis(trifluoromethylsulfonyl)imide. These complexes have been characterized by differential scanning calorimetry, single crystal X-ray crystallography, thermogravimetrical analysis, Raman spectroscopy and cyclic voltammetry. [Ag(MeCN)(4)](2)[Ag(Tf(2)N)(3)] is a room temperature ionic liquid. Smooth silver layers of good quality could be deposited from it, at current densities of up to 25 A dm(-2) in unstirred solutions. [Ag(EtIm)(2)][Tf(2)N] melts at 65 °C and can be used as an electrolyte for silver deposition above this temperature. [Ag(MeCN)][Tf(2)N] has a melting point that is too high to be useful in electrodeposition. Addition of thiourea or 1H-benzotriazole to the electrolyte decreased the surface roughness of the silver coatings. The morphology of the metal layers was investigated by atomic force microscopy (AFM). Adsorption of 1H-benzotriazole on the silver metal surface has been proven by Raman spectroscopy. This work shows the usefulness of additives in improving the quality of metal films electrodeposited from ionic liquids.     

Electrodeposition of rare earth metals Y,Gd, Yb in ionic liquids

The possibility of yttrium, gadolinium, and ytterbium electrodeposition from solutions of their triflates in different ionic liquids at 100°C was investigated. It was shown that these metals could be deposited on the cathode from electrolytes based on ionic liquids with quaternary ammonium cations, and these metals do not deposit from 1-butyl-2,3-dimethylimidazolium triflate. It was established that, in the case of butyltrimethylamonium triflate usage, metal deposition occurs on a copper electrode, and it does not occur on a platinum electrode, and in 1-butyl-1-methylpirrolidinium triflate, the reduction process is possible on both electrodes. Yb³⁺ reduction occurs step by step via Yb²⁺ formation. It was shown that the limiting stage of the cathode process is adsorption of a metal cation on the electrode.     

从2AlCl3/Et3NHCl离子液体中电沉积制备Ni 和Ni-Al 合金

在含Ni2+的2AlCl3/Et3NHCl离子液体中的铜电极上通过恒电位电沉积制备出金属Ni和Ni-Al合金.采用循环伏安和计时电流方法,揭示铜电极上沉积金属Ni的成核机理,研究了电沉积Ni-Al合金的机理,以及恒电位沉积Ni-Al合金工艺条件对沉积Ni-Al合金表面形貌和电流效率的影响.结果表明:在铜电极上电沉积金属Ni的成核机理为受扩散控制的三维瞬时成核过程.在电量≥3.0 C时,电沉积Ni-Al合金的组成基本不再变化.Ni-Al合金的电沉积机理为,Ni的电沉积受扩散控制,同时进行Al的欠电位沉积,在Ni-Al合金电沉积过程中某些Ni-Al合金相的沉积可能受动力学限制而使Ni-Al合金的组成偏离热力学预测结果.在电沉积Ni-Al合金的沉积电流小且平稳,电沉积速率慢条件下,Ni-Al合金表面形貌致密均一,反之就会出现瘤节.电沉积Ni-Al合金的电流效率＞90％.电沉积物的组成接近于Ni3Al合金.     

An Old Technique with A Promising Future: Recent Advances in the Use of Electrodeposition for Metal Recovery

Although the first published works on electrodeposition dates from more than one century ago (1905), the uses of this technique in the recovery of metals are attracting an increasing interest from the scientific community in the recent years. Moreover, the intense use of metals in electronics and the necessity to assure a second life of these devices in a context of circular economy, have increased the interest of the scientific community on electrodeposition, with almost 3000 works published per year nowadays. In this review, we aim to revise the most relevant and recent publications in the application of electrodeposition for metal recovery. These contributions have been classified into four main groups of approaches: (1) treatment and reuse of wastewater; (2) use of ionic liquids; (3) use of bio-electrochemical processes (microbial fuel cells and microbial electrolysis cells) and (4) integration of electrodeposition with other processes (bioleaching, adsorption, membrane processes, etc.). This would increase the awareness about the importance of the technology and would serve as a starting point for anyone that aims to start working in the field.     

The electrodeposition of composite coatings: Diversity,applications and challenges

A wide range of coatings can be produced by incorporating particles into an electrodeposit. The matrix may be a metal, conductive polymer or conductive ceramic, whereas the particle can be metallic, polymeric, ceramic or combinations of spheroidal, irregular or layered inclusions. Nanostructured, gradient, multilayer and sandwich layer deposit further widen possibilities. Electrochemical approaches to the deposition of composite coatings offer the benefits of good control over deposition rate (hence thickness), coating composition and deposit properties. Both faradaic electrodeposition and electrophoresis are usually involved. This review focuses on nanosized inclusions in a metal matrix over the last two decades. Interactions between bath composition, particle dispersion, operational variables and resultant deposit properties are poorly documented in the literature. Our understanding of the mechanism of composite deposition remains patchy, despite progress and computer models are scarce. Electrode geometry, electrolyte hydrodynamics and current distribution remain poorly treated. Markets in electronics, surface engineering, aerospace, corrosion protection and electrochemical energy conversion have been stimulated by newer uses for self-cleaning, superhydrophobic and biocompatible surfaces. Challenges to be met by further research and development are prioritised.     

共晶基离子液体的钴电化学沉积

通过恒电流和恒电位方法,研究了不同温度下脲-氯化胆硷（氯仿）基或乙二醇-氯化胆硷（氯仿）基离子液体中氯化钴溶液在铜和钢阴极上的钴电化学沉积行为. 采用扫描电子显微镜和X射线衍射技术,考察了不同试验条件对钴电沉积行为及钴沉积层形貌的影响. 结果表明,当沉积电位达到-0.8 V和沉积电流密度达到-6.0 A·m^-2时,温度范围从30 °C到90 °C,添加0.05 mol·L^-1的五氧化二磷,可以从脲基和乙二醇基离子液体中沉积得到光滑、发亮和良好结合力的金属光泽钴层. 电化学沉积钴的阴极电流效率达到98%.     

Copper(I)-containing ionic liquids for high-rate electrodeposition

New metal-containing ionic liquids [Cu(CH(3)CN)(n)][Tf(2)N] (n=2, 4; Tf(2)N=bis(trifluoromethylsulfonyl)- amide) have been synthesised and used as a non-aqueous electrolyte for the electrodeposition of copper at current densities greater than 25 A dm(-2). The tetrahedral copper(I)-containing cation in [Cu(CH(3)CN)(4)][Tf(2)N] is structurally analogous to quaternary ammonium and phosphonium ionic liquids and overcomes problems of metal solubility and mass transport. Two CH(3)CN ligands are removed at elevated temperatures to give [Cu(CH(3)CN)(2)][Tf(2)N], which can be used as a concentrated non-aqueous electrolyte. The structural and electrochemical characterisation of these compounds is described herein.     

Do all ionic liquids need organic cations? Characterisation of [AlCl2·nAmide]+ AlCl4(-) and comparison with imidazolium based systems

The addition of a simple amide to AlCl(3) causes the formation of a liquid of the form [AlCl(2)·nAmide](+) AlCl(4)(-). The material thus produced is liquid over a wide temperature range, is relatively insensitive to water and has the properties of an ionic liquid. This ionic liquid is shown to be a suitable medium for the acetylation of ferrocene and the electrodeposition of aluminium and demonstrated that quaternary ammonium cations are not always needed to form ionic liquids.     

Interaction between co-deposited metals during stripping voltammetry at boron-doped diamond electrodes

Electrochemical processes, which underlie the use of conductive diamond electrodes for the simultaneous detection of two or more metal ions in solution by anodic stripping voltammetry (ASV), have been investigated. The model analyte system studied contains the two metal species, Ag+(aq) and Pb2+(aq), and the experimental techniques employed include cyclic and square wave voltammetries, along with X-ray photoelectron spectroscopy and secondary electron microscopy. Although the bulk metallic forms of Ag and Pb are immiscible, several interactions in the system between the two metal species present are observed, which significantly influence the electrodeposition and electrodissolution processes which underlie ASV. The subsequent nucleation and growth of a given metal on the electrode surface is enhanced by the presence of the second metal on the surface. The encapsulation of one metal by the other, within the metal particulates that form on the electrode surface, significantly reduces the stripping yield at the potentials characteristic of the individual metals. The stripping potentials are also influenced by bonding interactions between deposited Ag and Pb, which broaden the characteristic stripping peaks in cyclic voltammetry, as well as producing underpotential deposition and stripping. Given these interactions, the extent to which ASV at diamond electrodes can be used to determine the solution concentrations of Ag+(aq) and Pb2+(aq) is considered.     

Ionic Liquids-New "Solutions" for Transition Metal Catalysis

Ionic liquids are salts that are liquid at low temperature (<100 degrees C) which represent a new class of solvents with nonmolecular, ionic character. Even though the first representative has been known since 1914, ionic liquids have only been investigated as solvents for transition metal catalysis in the past ten years. Publications to date show that replacing an organic solvent by an ionic liquid can lead to remarkable improvements in well-known processes. Ionic liquids form biphasic systems with many organic product mixtures. This gives rise to the possibility of a multiphase reaction procedure with easy isolation and recovery of homogeneous catalysts. In addition, ionic liquids have practically no vapor pressure which facilitates product separation by distillation. There are also indications that switching from a normal organic solvent to an ionic liquid can lead to novel and unusual chemical reactivity. This opens up a wide field for future investigations into this new class of solvents in catalytic applications.     

Carboxyl-functionalized task-specific ionic liquids for solubilizing metal oxides

Imidazolium, pyridinium, pyrrolidinium, piperidinium, morpholinium, and quaternary ammonium bis(trifluoromethylsulfonyl)imide salts were functionalized with a carboxyl group. These ionic liquids are useful for the selective dissolution of metal oxides and hydroxides. Although these hydrophobic ionic liquids are immiscible with water at room temperature, several of them form a single phase with water at elevated temperatures. Phase separation occurs upon cooling. This thermomorphic behavior has been investigated by (1)H NMR, and it was found that it can be attributed to the temperature-dependent hydration and hydrogen-bond formation of the ionic liquid components. The crystal structures of four ionic liquids and five metal complexes have been determined.     

Electrodeposition of Metals and Semiconductors in Air‐ and Water‐Stable Ionic Liquids

In addition to their stability, the advantages of air‐ and water‐stable ionic liquids over chloroaluminate ionic liquids, which were intensively investigated in the past, are that they are easy to dry, purify, and handle. Moreover, some of these ionic liquids have an extremely large electrochemical window of more than 5 V, and hence they give access to the electrodeposition of many metals and semiconductors, such as Ta, Ti, Si, and Ge. The results to date for the electrodeposition of metals and semiconductors in the most popular air‐ and water‐stable ionic liquids are presented.     

离子液体在有机反应中的应用

室温离子液体，由含氮的有机阳离子和无机阴离子组成，可溶解各种有机、无 机、金属有机化合物。它们没有蒸气压、不易燃、容易循环使用。近年已发现，离 子液体可广泛地用于许多过渡金属化合物和酶催化的反应。着重讨论这方面的发展 状况。     

A new method for practical electrodeposition of aluminium from ionic liquids

Successful electrodeposition of aluminium from ionic liquids has been long achieved scientifically. Nevertheless, standard industrial procedures have not yet been established due to the difficulties associated with using closed system filled with inert gas for the electrodeposition process. This paper presents a new methodology in which electrodeposition of aluminium is conducted in air, after preparation of ionic liquids in a glove box and covering them by a nonwater-absorbable layer of particular organic compound. This compound is stable and shows no reaction with the ionic liquid. Using this new methodology, functional aluminium layers were successfully deposited from a first generation ionic liquid AlCl₃/1-ethyl-3-methylimidazolium chloride – [EMIm]Cl – (60/40 mol%) on low carbon steel. Cyclic voltammetry (CV) measurements revealed that there was no significant difference in electrochemical properties characteristic of Al deposition when conducted in open air. SEM/EDX assessments showed that uniform, dense and adherent Al layers were obtained. Adherence of Al to the steel substrate was improved via in-situ electrochemical etching.     

Synthesis and characterization of volatile liquid cobalt amidinates

Three new volatile cobalt amidinate compounds were prepared: Co(tBuNC(R)NEt)2, R=Me, Et and n-Bu. They were characterized by elemental analysis, 1H NMR, X-ray structure analysis, melting point, vapor pressure, vaporization rate, thermal stability and chemical reactivity. They were found to evaporate cleanly without decomposition. Two of them are liquids at room temperature, allowing for more convenient preparation, handling and purification by distillation. They are highly reactive compounds that have been found to be suitable precursors for vapor deposition of cobalt metal, cobalt nitride and cobalt oxide. A new synthetic method allows for the facile and inexpensive preparation of large quantities of these compounds.     

钛基氧化铱电极电沉积制备技术研究进展

钛基氧化铱电极作为DSA(dimension stable anode)中的典型电极,广泛应用于各个领域.目前工业生产的钛基氧化铱电极主要由传统热分解法制备,存在成本高昂,工艺繁琐,依赖人工劳动,无法大规模生产等问题,十分有必要探索开发新的制备技术.本文从沉积液配方、基底材料的选择及处理、电沉积方式以及沉积时间等方面系...