The growth of hollow tubes, nanowire array, and segmented porous nanowire arrays made of Cu–Zn alloys in a Lewis acidic ZnCl2-1-ethyl-3-methylimidazolium chloride ionic liquid via direct electrodeposition without the need for a template is presented. The formation of each of type of structure is described. Hollow tubes result from the uneven overpotential gradient created at low Cu(I) concentration and low applied deposition overpotential. Nanowire arrays form under mass-transport-limited conditions, in which the ionic liquid speciation plays an important role. Segmented porous nanowire arrays are obtained by increasing the Cu(I) concentration to enhance the concentration profile vibration near the growth surface. The electrodeposited nanowire arrays show very good efficiency for the electrocatalytic reduction of nitrate ions in alkaline aqueous solution.

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Ionic liquid zinc chloride-1-ethyl-3-methylimidazolium chloride (IL ZnCl 2 -EMICl) with a ZnCl 2 /EMICl ratio of 40/60 mol% was used as the electrolyte to study the voltammetric behavior of Se(IV) introduced into the IL as selenium chloride (SeCl 4 ) or selenium oxide (SeO 2 ). The electrodeposition of ZnSe was performed using constant-potential electrolysis at tungsten electrodes via a two-stage approach from the IL with and without SeO 2 . The nucleation mechanism of Se at the tungsten electrodes agrees better with the three-dimensional instantaneous nucleation than the progressive nucleation based on Sharifker's model. Crystalline Se and approximately stoichiometric crystalline ZnSe electrodeposits could be obtained from this system. The ZnSe films showed photoelectrochemical activity with a bandgap energy of ∼2.5 eV. According to the experiments of the dependence of the photocurrent on the applied potential, the ZnSe film was determined to be a p-type semiconductor with the flatband potential V FB of −0. Zinc selenide (ZnSe) is a II-VI semiconductor that belongs to the chalcogenide family. ZnSe is usually obtained as a n-type semiconductor with a wide bandgap (2.67-2.7 eV). p-type ZnSe, which is very likely due to excess Se in the deposits, has been prepared using electrodeposition.1 ZnSe has been reported to be a useful material for various optoelectronic devices, such as lightemitting devices, window layers for solar cells, photovoltaic cells, laser screens, film transistors, photoelectrochemical cells, and optical components for infrared lasers. 19,25 Compared with these approaches, electrodeposition is more attractive [26][27][28][29] in terms of convenience, cost, and suitability for the large-scale production of thin films. Moreover, the surface morphology, composition, and properties of semiconductors can be flexibly controlled by adjusting the operating parameters such as electrodeposition potential or current, potential waveforms (constant potential or pulse potential), concentration of precursors, temperature, and additives. Therefore, ZnSe has been widely prepared using electrodeposition, with mostly successful results. Most electrodepositions of ZnSe were carried out cathodically in acidic aqueous baths containing Zn(II) and SeO 2 . [30][31][32][33][34][35][36][37] In acidic solutions, SeO 2 dissolves to form H 2 SeO 3 . ZnSe has also been electrodeposited from alkaline aqueous baths. [38][39][40] In alkaline solutions, Zn(II) and SeSO 3 2− are most frequently used as the precursors, and complexing agents, such as EDTA, are usually needed for forming strong complex ions with Zn 2+ to prevent the chemical precipitation of ZnSe, which is produced from the reaction between Zn(II) and SeSO 3 2− . Few studies have electrodeposited ZnSe from nonaqueous baths such as dimethylsulfoxide [41][42][43] and molten salts (CaCl 2 -NaCl at 550• C). 44,45 In almost all recent studies and applications of ZnSe semiconductors, ZnSe has been prepared using electrodeposition from aqueous baths. [46][47][48] 28,29,[50]...

Potential oscillation was observed during the template-free galvanostatic deposition in the 58/42 mol% AlCl 3 /trimethylamine hydrochloride ionic liquid, and resulted in the formation of unique periodic (accordion-like) aluminum wires with variable periodicity and diameter controlled by the deposition current density. Factors leading to this phenomenon are postulated. © The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email: oa@electrochem.org. [DOI: 10.1149/2.0021507eel] All rights reserved.Manuscript submitted March 19, 2015; revised manuscript received April 27, 2015. Published May 5, 2015 Potential oscillation during galvanostatic electrodeposition and current oscillation during potentiostatic electrodeposition are of interesting because these phenomena often associated with the production of deposits having interesting spatial patterns in the microor nano-scale. Many examples acquired in aqueous systems have been reported including tine metal latticework consist of cuboids connected by needles, 1,2 stacked alternated layers of metals or alloys, [3][4][5] dendrites, 6,7 and metal wires with periodically changed diameters. 8-10Often, the oscillation is associated with negative differential resistance (NDR), 11 and has been attributed to the reactions such as formation of passivation layer, autocatalytic growth, adsorption of additives (levelers and accelerants), and restricted mass transport of ions.Ionic liquids (ILs) have attracted numerous interests in electrochemistry and electrodeposition 12,13 especially for the deposition of materials such as Al 14 that are difficult to obtain from aqueous baths. Materials with various morphologies, specifically, metals/alloys wires, [15][16][17][18][19][20][21] have been electrodeposited from ILs with and without the need of template. Nevertheless, reports on electrochemical oscillation in IL are very limited. 22,23 Schaltin et al. 23 discussed the current oscillation during potentiostatic electrolysis of EMIC IL containing both Cu(II)/Cu(I), and found the presence of both Cu(II) and Cu(I) is essential for the oscillation to occur. Here, we report the potential oscillation during the template-free galvanostatic deposition of Al from a quiescent 58/42 mol% AlCl 3 /trimethylamine hydrochloride (AlCl 3 /TMHC) IL, which leads to the formation of Al wires with diameters change periodically. According to the literature, 24 The complex ion chemistry in the AlCl 3 /TMHC is similar to that for the AlCl 3 /1-ethyl-3-methylimidazolium chloride (AlCl 3 /EMIC) ILs, but the former ILs exhibit higher melting points and higher viscosities than the later ILs do. To our knowledge, galvanostatic de...