Potential Oscillation Associated Galvanostatic Deposition of Periodic Al Wires from a Chloroaluminate Ionic Liquid

In this article, we review the progress in the area of electrochemical technology with Lewis acidic haloaluminate room-temperature ionic liquids (RTILs), such as AlCl 3 -1-ethyl-3-methylimidazolium chloride and AlBr 3 -1-ethyl-3-methylimidazolium bromide, and novel chloroaluminate mixtures consisting of AlCl 3 and polarizable molecules, e.g., dimethylsulfone and urea, during this decade. The number of researchers in the field seems to increase steadily, because now we can handle haloaluminate RTILs and their mixtures with other solvents and materials more easily than we could in the past. In this review, we have categorized the electrochemical technology based on these RTILs into two topics: electroplating and energy storage. In fact, much of the current research is based on work begun during the period from ∼1970 until the 1990's. Room-temperature ionic liquids (RTILs), which is a name synonymous with room-temperature molten salts, have received considerable attention as novel reaction media, liquid materials, and starting materials for functional carbon material. (The name "ionic liquid" was arbitrarily chosen to represent what are actually salts that liquefy at temperatures below 373 K.) The interest in these materials stems from their favorable physicochemical properties, such as low-flammability, negligible vapor pressure, relatively high ionic conductivity, and high electrochemical stability. [1][2][3][4][5][6][7] It is now common knowledge in the chemistry community that many RTILs are stable in air or even water. The "first generation ionic liquids" were difficult to handle because the typical anions known at that time, e.g., AlCl 4 − and Al 2 Cl 7 − , reacted strongly with moisture in the air. Only a very limited number of laboratories with special skills for handling them could effectively use these RTILs. No doubt, the flourishing interest in RTIL chemistry was heavily abetted by the discovery of air and water stable systems, i.e., the so-called "second generation ionic liquids".However, we should not devalue the first generation systems such as those based on quaternary organic halide salts and aluminum halides, e.g., AlBr 3 and AlCl 3 , known as haloaluminates. The reactivity of the haloaluminates as well as their adjustable Lewis acidity is precisely what makes them interesting and very versatile. By contrast, the second-generation "inert" ionic liquids, are just that: inert and nonreactive, both chemically and electrochemically. Furthermore, the ionic conductivity and viscosity of the haloaluminates, which are important factors for the electrochemical applications described herein, exceed those for the comparable second-generation RTILs. For example, the ionic conductivity and viscosity for 60.0-40.0 mole percent (or 60 mol%) AlCl 3 -1-ethyl-3-methylimidazolium chloride ([C 2 mim]Cl) are 17.1 mS cm −1 and 15.35 mPa s, respectively, at 298 K.8 (In the interest of brevity, we will refer to the composition of these ionic liquids by simply stating only the amount of the aluminum halide.) On the other ...

Section: Deposition Of Al Nano/microstructuresmentioning

confidence: 97%

Review—Electrochemical Surface Finishing and Energy Storage Technology with Room-Temperature Haloaluminate Ionic Liquids and Mixtures

Tsuda

Stafford

Hussey

2017

“…In recent years, it has been discovered that several kinds of metals, such as Sn, [21][22][23] Zn, 24,25 Te, [26][27][28] Co, 29 Sb, 30 Al [31][32][33] and some alloys (Cu-Sn, 34 Sn-Si, 35 Cu-Zn, 36 Ni-Zn, 37 Fe-Co-Zn, 38 Co-Sm 39 and Co-Zn) 40 exhibit one-dimensional growth tendency in direct electrodeposition from specific ionic liquids. Some attempts are successful in template-free electrodeposition of wires, rods, belts and tubes under certain conditions accordingly.…”

mentioning

confidence: 99%

“…Nevertheless, the ionic liquids that can be used to directly electrodeposit 1D structures are reported rather limited. According to the recent literatures, [31][32][33] Al sub-microwires with diameter more than 200 nm are prepared by template-free electrodeposition, however the Lewis acidic AlCl 3 -trimethylamine hydrochloride ionic liquid was the only available electrolyte. Besides, it seems fairly difficult to directly electrodeposit uniform nanowires with diameter under 100 nm in ionic liquids without additional using of templates, catalysts or additives.…”

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confidence: 99%

Direct Electrodeposition of Aluminum Nanowires from a Room Temperature Ionic Liquid: An Electrochemical 2D-3D-1D Process

Wang

2018

Single-crystalline Al nanowires with diameters under 100 nm are successfully prepared by direct electrodeposition from a room temperature ionic liquid without using templates, additives or catalysts for the first time. We propose the three stages of nanowires growth mechanism including electrodeposition of the initial two dimensional nanofilm, subsequent electrochemical formation of three dimensional nano-nuclei and final one dimensional growth of nanowires. The electrodeposited Al nanowires can grow to lengths of up to 50 μm in 120 s with an average growth rate more than 0.4 μm/s, reaching a high aspect ratio over 1000. This study shows that the dimensions of nanowires are precisely controlled through the variation of electrode potential and are influenced by the electrodeposition temperature and time. The morphology of Al nanowires is very uniform and the nanowire diameters electrodeposited at −1.6 V/25 • C within 60 s are in the range of 17 nm to 50 nm. It is found that diffusion strongly influences the growth process.

“…25,26 Nanowires that are difficult to be electrodeposited from aqueous baths have been successfully electrodeposited from various ILs with template-assisted [27][28][29][30][31] and template-free methods. [32][33][34][35][36][37][38][39][40][41][42][43] Recently, by taking the advantage of the unique properties of chloroaluminate ILs, 44 we have demonstrated the template-free electrochemical fabrication of diameter-modulated Al wires can be achieved from a Lewis acidic chloroaluminate ionic liquid (IL) by using a pulse potential deposition method. 45 In that report, the deposited wire diameter was thinner when the potential was pulse at a more negative cathodic value, and the wire diameter got thick when the potential was pulsed to a less negative cathodic value, and by repeating the pulse sequence, wires with modulated-diameter were obtained.…”

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confidence: 99%

Template-Free Fabrication of Diameter-Modulated Co-Zn/Oxide Wires from a Chlorozincate Ionic Liquid by Using Pulse Potential Electrodeposition

Chang

Sun²

2017

Diameter-modulated Co-Zn wires consisting of beads which are linked by stems can be prepared by using a square-wave pulse potential electrodeposition method from a 40-60 mol% ZnCl 2 -EMIC ionic liquid containing 5.0 mol% CoCl 2 at 70 • C without the use of a template. The effects of pulse potential and pulse duration on the physical dimensions of the Co-Zn wires such as the diameters of the stem and bead as well as the spacing between the beads were investigated by scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM). It is concluded that the sizes of the segmented Co-Zn wires can be tuned by changing the pulse potentials and durations.