Kinetics of electroreduction of Zn 2+ at mercury in nonaqueous solutions

Abstract

The electroreduction of Zn 2+ was studied in propylene carbonate (PC), acetonitrile (ACN), and hexamethylphosphoramide (HMPA) on mercury at various concentrations of tetraethylammonium perchlorate as a supporting electrolyte using dc polarography, cyclic voltammetry, chronoamperometry, and ac polarography. It was found that in PC and ACN the electroreduction process proceeds in one step. In HMPA, however, the electroreduction proceeds through a CEE mechanism in which a chemical reaction is followed by a charge transfer in two steps. The heterogeneous rate constants, corrected for the double layer effects, decrease with increase in the solvent donor number. The electroreduction process proceeds through the cation transfer mechanism.