Morphological dependence of silver electrodeposits investigated by changing the ionic liquid solvent and the deposition parameters

Abstract

The low toxicity and environmentally compatible ionic liquids (ILs) are alternatives to the toxic and harmful cyanide-based baths used in industrial silver electrodeposition. Here, we report the successful galvanostatic electrodeposition of silver films using the air and water stable ILs 1-ethyl-3-methylimidazolium trifluoromethylsulfonate ([EMIM]TfO) and 1-H-3-methylimidazolium hydrogen sulphate ([HMIM(+)][HSO4(-)]) as solvents and AgTfO as the source of silver. The electrochemical deposition parameters were thoughtfully studied by cyclic voltammetry before deposition. The electrodeposits were characterized by scanning electron microscopy coupled with X-ray energy dispersive spectroscopy and X-ray diffraction. Molecular dynamics (MD) simulations were used to investigate the structural dynamic and energetic properties of AgTfO in both ILs. Cyclic voltammetry experiments revealed that the reduction of silver is a diffusion-controlled process. The morphology of the silver coatings obtained in [EMIM]TfO is independent of the applied current density, resulting in nodular electrodeposits grouped as crystalline clusters. However, the current density significantly influences the morphology of silver electrodeposits obtained in [HMIM(+)][HSO4(-)], thus evolving from dendrites at 15 mA cm(-2) to the coexistence of dendrites and columnar shapes at 30 mA cm(-2). These differences are probably due to the greater interaction of Ag(+) with [HSO4(-)] than with TfO(-), as indicated by the MD simulations. The morphology of Ag deposits is independent of the electrodeposition temperature for both ILs, but higher values of temperature promoted increased cluster sizes. Pure face-centred cubic polycrystalline Ag was deposited on the films with crystallite sizes on the nanometre scale. The morphological dependence of Ag electrodeposits obtained in the [HMIM(+)][HSO4(-)] IL on the current density applied opens up the opportunity to produce different and predetermined Ag deposits.

A Review on Surface-Enhanced Raman Scattering

“…A reference electrode is necessary for the precise application or variation of the potential at the working electrode while a counter electrode made of platinum or graphite allows one to close the amperometric circuit. Basically, all the metals in the periodic table can be nanostructured in different shapes (i.e., spherical, cubical, dendrite, and fractal-like) by ER or ED, even though the most commonly used are silver, gold, and copper [165,374]. Briefly, ER consists of the application of very short pulses (20 ms) at very positive potential to prompt the dissolution of small areas of metal from the initially smooth pristine surface, followed by a second pulse at a more negative potential to induce the random redeposit of the metal back onto the electrode.…”

Ionic Liquids Electrodeposition of Sn with Different Structures as Anodes for Lithium-Ion Batteries

“…According to the literature data, the viscosity values of the [EMIm]BF 4 , [EMIm]TfO and [EMIm]DCA ionic liquids are 37.7 (295 K), 52 (298 K) and 19.8 cP (301 K), respectively. 26,37 Relatively large viscosity differences are occurred in the three solutions. The reduction peak current density of Sn(II)/Sn in the [EMIm]DCA ionic liquid is obviously higher than those in the [EMIm]BF 4 and [EMIm]TfO ionic liquids.…”

“…The much lower viscosity of [EMIm]DCA ionic liquid means more efficient mass transport and higher conductivity. 26,37 Therefore, the shift in reduction peak potential of Sn(II)/Sn in these systems may also be associated with the diffusion process. The shifts in [EMIm]BF 4 and [EMIm]TfO ionic liquids seem more easily to be caused by diffusion limitation.…”

Silver nanoparticles/free-standing carbon nanotube Janus membranes.

“…There is a substantial literature on the electrochemical preparation of silver structures in aqueous medium [25][26][27][28][29][30][31][32][33][34][35], highly dependent on the bath's composition and on the electrodeposition conditions as the manner that different morphologies and structures could be obtained. However, more recently, different deep eutectic solvents [36][37][38], chloroaluminate melts [39,40] and room-temperature ionic liquids [41][42][43][44][45][46][47][48][49] are receiving a growing attention as green electroplating solutions for silver deposition taking advantage of thermal and chemical stability, negligible low vapour pressure, reasonable ionic conductivity and moderate viscosity of these new solvent. Due to the high positive standard potential value of silver and with the aim of tailoring the silver deposition at less positive potentials than in aqueous medium without the use of extreme low concentrations we explore the AgNPs deposition in ionic liquids.…”