Studies of Metal Electrodeposition in Adiponitrile

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 PowerSuite^TM  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.

                                                                                                                                                                                                                                                                    References

1.  L. M. A. Monzon, F. Byrne, J. M. D. Coey,  J. Electroanalytical Chemistry, 657,54–60 (2011).

2.  P. Heoa, R. Ichino, M. Okido,  Electrochimica Acta, 51, 6325–6330 (2006).

3.  A. P. Abbott and K. J. McKenzie,  Phys. Chem. Chem. Phys., , 8, 4265–4279 (2006).

4.  G. Cheek, Abstract I1-2481, 224^thElectrochemical Society Meeting, San Francisco, CA, 29 October 2013.

5.  P. G. Sears, J. A. Caruso and A. I. Popov,  Journal of Physical Chemistry, 71(4), 905 (1967).

6.  H. Duncan, N. Salem, and Y. Abu-Lebdeh, J. Electrochem. Soc., 160 (6) A838-A848 (2013).

7.  M. Miranda-Hernandez,  I. Gonzalez, and  N. Batina,  J. Phys. Chem. B, 105(19), 4214 (2001).

Figure :  Cyclic voltammograms of  17 mM  AgNO₃  in adiponitrile (1.00 M TEA BF₄) at 1 mm diameter electrodes, 25 mV/s.

(a)     Platinum electrode            [ black curve ].

(b)     Vitreous carbon electrode  [ red curve ].