Ionic Liquid Electrodeposition Research Articles

Combined Flame and Electrodeposition Synthesis of Energetic Coaxial Tungsten-Oxide/Aluminum Nanowire Arrays

A nanostructured thermite composite comprising an array of tungsten-oxide (WO2.9) nanowires (diameters of 20-50 nm and lengths of >10 μm) coated with single-crystal aluminum (thickness of ~16 nm) has been fabricated. The method involves combined flame synthesis of tungsten-oxide nanowires and ionic-liquid electrodeposition of aluminum. The geometry not only presents an avenue to tailor heat-release characteristics due to anisotropic arrangement of fuel and oxidizer but also eliminates or minimizes the presence of an interfacial Al2O3 passivation layer. Upon ignition, the energetic nanocomposite exhibits strong exothermicity, thereby being useful for fundamental study of aluminothermic reactions as well as enhancing combustion characteristics.

Material Characteristics and Corrosion Performance of Heat-Treated Al-Zn Coatings Electrodeposited on AZ91D Magnesium Alloy from an Ionic Liquid

This study examined co-deposition of Al and Zn on active AZ91D magnesium alloy using ionic liquid electrodeposition. A room temperature Lewis acidic ionic liquid made of aluminum chloride (AlCl3) and 1-ethyl-3-methylimidazolium chloride (EMIC) with a mole ratio of 60:40 was used as the bath for pure Al electrodeposition, while the addition of 1 wt% ZnCl2 to this electrolyte was used for co-deposition of Al-Zn on AZ91D magnesium alloy. The material characteristics and corrosion performance of the as-deposited films formed under various deposition charges and those annealed at 200 and 300°C were investigated. The experimental results showed that both pure Al and Al-Zn coatings provided adequate passivity for the AZ91D magnesium alloy. The re-distribution of the chemical composition after heat-treatment, including the formation of intermetallic compounds, gave rise to an increased microhardness and improved passivation behavior of the Al-Zn coated AZ91D magnesium alloy.

3D ordered macroporous germanium fabricated by electrodeposition from an ionic liquid and its lithium storage properties

Among the group IVA materials, germanium has a large theoretical specific capacity, good electrical conductivity and fast lithium ion diffusivity, making it an alternative anode material for Li ion batteries. Nanostructured electrodes now are the biggest focus to solve the volume expansion problem and to improve cycling and rate performance. Ionic liquid electrodeposition was used to obtain Ge nanoparticles at room temperature, and by combining with a “hard” template, 3D macroporous frameworks have been easily synthesized. 3D ordered macroporous Ge exhibits a reversible capacity of 1024 mA h g−1 and retains a capacity of 844 mA h g−1 after 50 cycles at a rate of 0.2 C.

One-step fabrication of nanostructured NiO films from deep eutectic solvent with enhanced electrochromic performance

Nanostructured NiO thin films were directly prepared by simple and efficient electrodeposition in a choline chloride-based ionic liquid. Uniform granules and some open voids between these granules are observed in the film deposited at 70 °C, while the film becomes compact and the NiO particles are 2–6 nm in size when the electrodeposition temperature is 90 °C. The optical transmittance of the film increased with the increase of the electrodeposition temperature. Although the electrochromic switching and reaction kinetics of the NiO film deposited at low temperature are fast due to the presence of metallic Ni and some voids, little transmittance modulation occurs in the wavelength range of 300–900 nm. In contrast, the NiO film deposited at high temperature exhibits high optical modulation of 67% at 550 nm, high coloration efficiency (98 cm2 C−1 at 400 nm, 92 cm2 C−1 at 550 nm and 51 cm2 C−1 at 750 nm), good memory effect and cycling durability.

Two-dimensional SixGe1−x films with variable composition made via multilayer colloidal template-guided ionic liquid electrodeposition

The binary alloy system Si(x)Ge(1-x) provides a continuous series of materials with gradually varying properties. In this paper, we report on a fundamental basis a method to make large-area macroporous Si(x)Ge(1-x) films with variable Ge content by electrodeposition in an ionic liquid, with SiCl(4) and GeCl(4) as precursors. The chemical composition of the products can be modified by changing the molar ratio of the precursors. Periodical macroporous Si(x)Ge(1-x) was made by a multilayer polystyrene (PS) template assembled as face-centered cubic lattice. Two-dimensional (2-D) Si(x)Ge(1-x) bowl-like and fishing-net structures can be obtained by applying different deposition temperatures. The results highlight the potential applications, including photonic bandgap and battery materials, as well as ultra-thin gratings, due to the effect of modification of light and improved tunability of composition, although Si(x)Ge(1-x) made by our method is sensitive to oxidation by air.

The electrodeposition of aluminum on TiB2/A356 composite from ionic liquid as protective coating

The electrochemical deposition of aluminum using ionic liquid of AlCl3-1-ethtyl-3-methylimidazolium chloride (AlCl3-[EMIm]Cl) was studied to improve the corrosion resistance of TiB2/A356 composites. The effects of experimental parameters (e.g., current density, deposition time and electrolyte temperature) on the deposit morphology and cathode current efficiency were investigated. The results indicated that the experimental parameters can greatly affect the morphology of Al coatings. Sustaining at a relatively high percentage (≥97.0%), the cathode current efficiencies showed varied dependence on different parameters. The optimum conditions for producing dense and uniform Al coatings were determined, with the current density of 1.0A/dm2, deposition time of 60min and electrolyte temperature of 30°C. The electrochemical behavior was evaluated by potentiodynamic polarization curves and cyclic voltammogram. It was found that the corrosion resistance of the TiB2/A356 composite was greatly enhanced by Al electrodeposition in ionic liquid.

ELECTRODEPOSITION OF CoAg FILMS FROM EMIC IONIC LIQUID

CoAg films were prepared by ionic liquid electrodeposition to replace conventional aqueous electrodeposition on a copper substrate. Effects of different EMIC concentrations on composition, microstructure and magnetic properties of CoAg films were investigated. With the increase of 1-Ethyl-3-methylimidazolium Chloride (EMIC) concentration, atomic percentage of cobalt in CoAg films increased dramatically but amounts of silver reduced gradually. Almost all of the deposited films were crystalline and contained fcc- Ag(200) and hcp- Co(002) diffraction peaks. With the increase in EMIC concentration, the intensity of Co(002) peaks increased, which led to better crystalline and larger grain size. Dissimilar surface morphology of CoAg films from different EMIC concentration systems could be detected. CoAg films with bigger grain size and rougher surface could be obtained when higher concentration of EMIC was introduced during the electrodeposition. Especially, CoAg films with rice-like structures could be observed when EMIC was 0.45 mol/L. With the increase of EMIC concentration, coercivity of CoAg increased gradually from 140 Oe to 260 Oe.

Ultra fast electrochromic switching of nanostructured NiO films electrodeposited from choline chloride-based ionic liquid

Nanostructured nickel oxide (NiO) thin films were prepared by a simple electrodeposition in choline chloride-based ionic liquid followed by an oxidation in air. Uniform granules and some voids opened between these granules were presented in the polycrystalline NiO films deposited for 10 and 30s, but the film became compact as the deposition time increased to 60s. The optical transmittance of the film decreased with the increase of the film thickness. All the NiO films exhibit high coloration efficiency, fast electrochromic switching and good cycling durability. The ultra fast switching time (0.74s and 0.88s) and maximum coloration efficiency of 250cm2C−1 were observed for the film deposited for 10s.

Phosphorylated manganese oxide electrodeposited from ionic liquid as a stable, high efficiency water oxidation catalyst

Efficient production of hydrogen via water splitting is an important goal that would represent a significant step towards truly sustainable supplies of energy. However, currently available catalysts for water electrolysis are either too low in efficiency or too unstable to be practical in this context. Recognizing the very high stability of manganese phosphate, we describe here a novel catalyst material based on manganese oxide that is both stabilized and sensitized by a surface phosphorylation reaction in an ionic liquid electrodeposition process. XPS and EXAFS data show that the surface of the MnOx contains phosphorous at P to Mn ratio of ∼1:2, indicating that the surface layer contains both phosphate characteristics and oxide characteristics. The catalyst stability was significantly enhanced compared to the previously reported manganese oxide catalysts and more than 25h of continuous water oxidation is demonstrated.

Templated Electrodeposition of Si Nanowires from Ionic Liquid

Electrodeposition of Si has gained interest recently due to the relative simplicity of electrochemical processing over conventional methods of Si deposition. In this report, we present our progress in the development of Si nanowire arrays electrodeposited from SiCl4 in an ionic liquid electrolyte, specifically tri-methylhexyl ammonium (TMHA+) bis(trifluorosulfonyl) amide (TFSA-). Characterization of deposition conditions for nanowires, as well as preliminary results for electrochemical quartz crystal microbalance (EQCM) measurements of planar deposits are discussed as part of our effort to further the understanding of the reaction mechanisms in Si electrodeposition in ionic liquid.

Progress in Nanowire Growth and Mechanistic Analysis of Silicon Electrodeposition in Ionic Liquid

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Zn, Ti and Si nanowires by electrodeposition in ionic liquid

An electrochemical route for the fabrication of zinc, titanium and silicon nanowires from ionic liquid (IL) based plating solutions is presented. Thanks to the large potential window of IL and good solubility of the corresponding anhydrous chloride salts, the presented method proceeds by a kinetically controlled electrochemical decoration of step-edges at highly oriented pyrolytic graphite surface. Resulting rather crystalline nanowires are more than a few hundreds of μm long while their diameter can be controlled in the 10 to 100 nm range by the electrolysis duration.

Gold electrodeposition in organic media

Organic species are easily adsorbed onto metal electrodes, due to the high surface energy. This principle is widely employed in electrodeposition to obtain grains with a given shape and size. Electrodeposition in organic electrolytes and ionic liquids is expected to produce deposits whose properties will be modified by the nature of the species present in the bath. Here, we analyse the voltammetric profiles for the reduction of two different gold complexes, tetrachloroaurate (III) ( AuCl 4 - ) and dicyanoaurate (I) ( Au ( CN ) 2 - ), in dimethylsufoxide (DMSO) and in the ionic liquid tributylmethylammonium bis(trifluoromethylsulfonyl)imide (TBMA + NTf 2 - ). We evaluate how organic cations present in the electrolyte modify not only the voltammetric response but also the morphology of the deposits obtained. The films range from very smooth with a rms roughness of ∼10 nm for 500 nm film to rough globular or facetted films with a crystalline size of ∼200 nm.

Growth and Shape-Ordering of Iron Nanostructures on Au Single Crystalline Electrodes in an Ionic Liquid: A Paradigm of Magnetostatic Coupling

Fe electrodeposition on Au(111) and Au(100) in BMIBF(4) ionic liquid is found to form hitherto unreported shape-ordered nanoscale morphologies of pseudorods and pseudosquare rings, respectively, both composed of grains of 4-7 nm. The manner of growth of the square rings is a ring-on-ring structure with enlarging side length and slightly protruding four corners. The generality of the growth mechanism is verified by the formation of almost exactly the same shape-ordered Fe nanostructures on Pt, i.e., pseudorod structure on Pt(111) and pseudosquare rings Pt(100). These structures are explained within the framework of magnetostatic interactions of spontaneously magnetized grains under crystallographic constraint of the substrate surface, which result in an antiparallel arrangement in magnetization of the grains at pseudorods and magnetic flux closure at the pseudosquare rings. The closed magnetic flux further leads to magnetic field-enhanced growth at the four corners and the outer peripheries of the pseudosquare rings. The observed shape-ordering of the Fe thin film serves as a paradigm of magnetostatic coupling, in which the roles of ionic liquid as surfactant and magnetic media may not be underestimated. The present work adds a new dimension to electrodeposition in ionic liquid, by which new magnetic film structures may be expected.

Preparation of Cu 2ZnSnS 4 films by electrodeposition using ionic liquids

We report a new technique for the growth of Cu 2ZnSnS 4 (CZTS) thin films. The CZTS thin films were successfully formed by electrodeposition in ionic liquid and sulfurized in elemental sulfur vapor ambient at 450 °C for 1.5 h using Argon as the carrier gas. Experimental data on X-ray diffraction indicated that the film has a kesterite structure with preferred grain orientation along (1 1 2). It is found that the energy bandgap of the film is about 1.49 eV and the optical absorption coefficient is in the order of 10 4 cm −1. The results are compared to a control film grown by e-beam deposition of elemental stacked layers followed by the same sulfurization process. The data show that the two films have comparable optoelectronic properties indicating that electrodeposition in ionic liquid is a viable process for the growth of CZTS films for applications in photovoltaic device. The XRD results also indicate an absence of the oxide peak in the material, which is commonly found in films grown by electrodeposition in aqueous solutions.

Electrochemical Template Deposition of Aluminum Nanorods Using Ionic Liquids

A new method for synthesizing aluminum nanorods has been developed and demonstrated using nonaqueous, ionic liquid electrodeposition in nanoporous, polycarbonate templates. The nanorods, which have diameters of 40 and 60 nm and lengths of 2−4 μm, are characterized by SEM, EDX, UV−visible, and ultrafast spectroscopy.

Growth of Silicon Nanowires of Controlled Diameters by Electrodeposition in Ionic Liquid at Room Temperature

Silicon nanowires were fabricated for the first time by electrochemical template synthesis at room temperature. This innovative, cheap, and simple process consists of electroreduction of Si ions using a nonaqueous solvent and insulating nanoporous membranes with average pore diameters from 400 to 15 nm which fix the nanowires diameters. Characterization techniques such as scanning and transmission electron microscopies, infrared absorption measurements, X-ray diffraction experiments, energy dispersive X-ray, and Raman spectrometries show that the as-deposited silicon nanowires are amorphous, composed of pure Si and homogeneous in sizes with average diameters and lengths well matching with the nanopores' diameters and the thicknesses of the membranes. Thanks to annealing treatments, it is possible to crystallize the Si nanowires, demonstrating the potentiality for this innovative electrochemical process to obtain a wide range of Si nanowires with well controlled diameters and lengths.

Ionic liquid electrodeposition of reactive metals

Ionic liquids are solvents of interest for applications such as electroplating, winning and refining of metals. Of particular interest is the possibility of processing reactive metals such as aluminium, magnesium and titanium that cannot be deposited from aqueous solutions. Aluminium has been electrodeposited from AlCl3: ionic liquid mixtures at low temperatures relative to conventional Hall–Héroult smelting. Imidazolium ionic liquids have been used in the past due to their relatively high ionic conductivity and cation stability. The less studied and less expensive phosphonium ionic liquids systems may provide a viable alternative to imidazolium ionic liquids for certain applications. New information regarding the physical properties and electrochemical behaviour of phosphonium ionic liquid systems is presented.

Surface Analysis of Nanoscale Aluminium and Silicon Films Made by Electrodeposition in Ionic Liquids

We present a spectroscopic and microscopic study of nanoscale Al and Si films electrodeposited in water- and air-stable ionic liquids. The choice of cations for such ionic liquids has previously been shown to have a significant effect on the crystallite size of electrodeposited Al or Si films. We found that the deposits are generally uniform, dense, metallic bright, and adherent with crystallite sizes in the nanometer range. The nanocrystalline films were characterized using X-ray Photoelectron Spectroscopy (XPS) and High-Resolution Scanning Electron Microscopy (HRSEM). The XPS results show that the surface of both films is oxidized although the deposition was done in an inert gas glove box. Furthermore our results suggest that as a consequence of oxygen attack the nanoparticles are composed of a metallic core surrounded by a thin oxidic shell. Our XPS study also shows that neither the cation nor the anion of the ionic liquid is entrapped in the deposit. Thus, electrodeposition in ionic liquids delivers pure materials.

Electrodeposition of Cu2ZnSnS4 Thin Films Using Ionic Liquids

AbstractWe report the growth of Cu2ZnSnS4 (CZTS) thin films by electrodeposition in ionic liquid. Sulfurization was performed in elementary sulfur vapor environment at 450°C for 2 hours. The X-ray diffraction analysis indicated that the film has a stannite structure with preferred grain orientation along (112). Photo-absorption measurement of the sample was performed from 500 nm to 990 nm. It is found that the energy bandgap of the film is about 1.49eV and the absorption coefficient is found to be of the order of 104cm-1.