Anion Effects on the Solid/Ionic Liquid Interface and the Electrodeposition of Zinc

Abstract

The effect of anions on the solid/ionic liquid (IL) interface and the electrodeposition of zinc have been investigated. The employed ILs are composed of 1-ethyl-3-methyl­imidazolium ([EMIm]+), bis­(trifluoro­methyl­sulfonyl)­imide (TFSI–), trifluoro­methyl­sulfonate (TfO–), methyl­sulfonate (OMs–) and acetate (OAc–). These anions show an increasing cation–anion interaction strength in the order TFSI– < TfO– < OMs– < OAc–, as probed by far-infrared spectroscopy below 200 cm–1. It was shown by in situ AFM that the anion has a profound impact on the interfacial properties. Multilayered structures were observed at the electrode/IL interface for [EMIm]­TFSI and [EMIm]­TfO, respectively, while only a few layers with rather a low push-through force were found at the interface for [EMIm]­OMs and [EMIm]­OAc, respectively. The coordination of Zn­(II) ions in these ILs by varying zinc salts was investigated by Raman spectroscopy. The differences in metal species and interfacial layers have a strong influence on the electrochemical process and on the quality of the deposits. Dense zinc deposits with nanowire-like and hexagonal plate-like structures were obtained from ILs with TFSI– and TfO– anions, respectively. Thin layers of zinc with porous and spongy structures were obtained in ILs with OMs– anion containing 0.2 mol/L zinc salts, while homogeneous and smooth deposits with a fine-grained structure were obtained with 1 mol/L zinc salts. However, no deposits were found in Zn­(OAc)2/[EMIm]­OAc under the same conditions. These results indicated that the anions of ILs strongly affected the solid/IL interface, the speciation of Zn­(II) ions in ILs, and the morphology of zinc deposits.

Atomic Force Spectroscopy on Ionic Liquids

“…Moreover, the configuration of the anions can also have an impact on the interfacial structure as was addressed, e.g., by Liu et al [ were investigated in contact with the Au (111) surface. AFS measurements under cathodic polarization revealed that the number of layers and force necessary for their punctuation increases systematically with anion size, and it was concluded that this is also the cause for differences in macroscopic electrowetting behavior [97].…”

“…97]. In their work, ionic liquids having the same [EMIm] + cation but four different anions bis(trifluoromethylsulfonyl)imide[TFSI] …”

Ultrathin ionic liquid films on metal surfaces: adsorption, growth, stability and exchange phenomena

“…IL interfaces are particularly important for interface-controlled applications such as sensor [4,[16][17][18][19], lubrication [20][21][22], separation [4,19,[23][24][25][26][27][28][29], electrochemistry [4,19,[30][31][32][33][34][35][36][37][38][39] and electronics [40][41][42] technologies. ILs further stimulated completely new concepts for catalysis [1,4,[43][44][45][46][47][48][49][50][51][52][53][54][55][56][57].…”

How a Transition‐Metal(II) Chloride Interacts with a Eutectic AlCl3‐Based Ionic Liquid: Insights into the Speciation of the Electrolyte and Electrodeposition of Magnetic Materials

“…[29] For metal-ion speciation in ILs (or DESs), we refer to ac ritical review by Estager et al and to other relevant articles that are available in the literature. [30][31][32][33][34] The influence of ligands on the asymmetric cleavage and on the nature of the coordination and the number of coordination sites is still required forad etailed understandingo fL CCs. For instance, complexes formed from AlCl 3 and neutral ligands ( 4-propylpyridine or N-butylpyrrolidine) are different upon varying the concentration of AlCl 3 in the mixtures.…”

“…Corresponding to this bending of the hysteresis curve at high inductions, ar apid increase in high inductionl osses is also found. [32] The bending of the hysteresis curve as well as the high induction losses are controlled by domain-wall nucleation and annihilation processes as well as by rotationo fm agnetic moments. [72][73][74][75] Reasonsf or the in- crease of high induction losses are the presence of non-magnetic pores or non-magnetic inclusions like iron oxidesi nt he deposited material as well as unfavorable orientations of the grains misaligned to the magnetic easy axis.…”