Ion Pairing as a Method of Controlling the Composition of Electrodeposited Alloys

Abstract

A study was made of the possibility of controlling the composition of electrodeposited alloys by the use of noncomplexing ion‐pairing salts. It was shown both voltammetrically and by analysis of electrodeposits that the addition of ion‐pairing cations increased the rate of deposition of tin significantly (because of ion‐pairing with the negative stannite or stannate ion) and slightly decreased the rate of deposition of the positively charged copper. As a consequence of this, the addition of tetrabutylammonium perchlorate increased the ratio of tin to copper in the deposit. The lowering of the dielectric constant of the solution by addition of tert‐butyl alcohol increased the ion‐pairing and, thus, increased this effect. Similarly, it was shown that the quaternary salt increased the current efficiency for deposition of tin and slightly decreased the current efficiency for deposition of copper.

Electrodeposition of nanocrystalline zinc‑tin alloy from aqueous electrolyte containing gluconate in the presence of polyethylene glycol and hexadecyltrimethylammonium bromide

“…Quaternary ammonium salts (QAS) such as CTAB are used as an inhibitor or catalyst in electroplating [45,46]. This cationic surfactant electrostatically interacts with the electrode surface.…”

“…Small concentration of CTAB could adsorb on active sites of the surface and act as a deactivating inhibitor; or could partially cover the surface and slow down the electro-reduction processes [47]. In case of electrodeposition of anionic species, CTAB cations provide sites for ion pairing and reduce the energy barrier for the deposition of the anionic species which are not electrically driven to a negatively charged surface of working electrode at the potential region of electrodeposition and thus act as a catalyst [46,48]. On the other hand, in case of the cationic nature of depositing species, CTAB competes with cations of depositing species and hinders the deposition process, hence acts as an inhibitor [46,48].…”

The influence of sodium diphenylamine sulfonate on the electrodeposition of Mg–Ni alloy and its electrochemical characteristics

“…To date, many models in these studies have been proposed, such as: one could increase the current efficiency for processes either by inhibiting the electrolysis of water or by catalyzing the desired electrochemical processes [4], one could inhibit the oxidation of water by the formation of hydrophobic films [5], one could decrease the reduction potential of the metal [6], one could inhibit the reduction of water by the formation of insoluble films of inorganic compounds [7], or one could increase the limiting reduction current [8]. Franklin and coworkers found that organic compounds were absorbed on the metal surfaces by inhibiting the rates of the redox reaction [9], changing the concentration of redox reaction species [10], shifting equilibrium potentials at the electrode [10]. Therefore, SDS appeared to be an interesting organic additive.…”