Studies of Metal Electrodeposition in Adiponitrile

Abstract

Introduction Electrodeposition of certain metals, particularly active metals and some noble metals, sometimes employ nonaqueous solvents (1,2,3), among other reasons, to obtain wider potential limits than those provided by water. Recent work in this laboratory has involved the use of adiponitrile [NC(CH2)4CN] as an electrochemical solvent (4). It is evident that adiponitrile has desirable properties such as a moderately high dielectric constant, high boiling point, and an extremely wide potential range (5, 6). The present abstract represents work involving the use of adiponitrile as an electrochemical solvent for electrodeposition of metals, particularly silver, onto various substrates. Experimental Adiponitrile was obtained from Aldrich Chemical Co. Tetraethylammonium tetrafluoroborate [TEA BF4] was purchased from Southwestern Analytical Chemicals (SACHEM). Voltammograms were taken with a PAR283 potentiostat using PowerSuiteTM software. Potentials are reported with respect to a Ag/AgCl (0.1M EMICl in EMI BF4) reference electrode (Cypress Systems). Vitreous carbon and platinum electrodes were obtained from Cypress Systems. All experiments were carried out in a Vacuum Atmospheres drybox. Results and Discussion In order to investigate the effectiveness of adiponitrile as a solvent for electrodeposition, cyclic voltammograms of silver deposition, from dissolved silver nitrate, were carried out in adiponitrile / 1.00 M TEA BF4. The figure at the end of this abstract shows a well-defined reduction process at platinum, followed by a rather narrow stripping peak on the return sweep. At vitreous carbon, the deposition potential shifts to a less positive deposition potential, with significant oxidative activity ( silver stripping ) after the main stripping peak. The behavior observed at vitreous carbon apparently reflects the presence of active areas on the carbon surface (7), accounting for the extended stripping process. The facile electrodeposition of silver from adiponitrile gives hope that this solvent is a feasible choice for metal deposition. Attempts at electrodeposition of other metals, particularly aluminum, are also intended for presentation.