Zinc Electrodeposition in the Presence of an Aqueous Electrolyte Containing 1-Ethylpyridinium Bromide: Unexpected Oddities

Abstract

The reversible electrodeposition of zinc was investigated in an aqueous electrolyte containing zinc bromide (50 mM) and 1-ethylpyridinium bromide ([C2Py]Br, 50 mM) by cyclic voltammetry, chronoamperometry, and scanning electron microscopy. Unusual voltammetric behaviour for the Zn/ZnII redox couple was observed in the presence of [C2Py]Br. Passivation of the redox couple was observed after a single deposition–stripping cycle at switching potentials more negative than −1.25 V versus Ag/AgCl. This unusual behaviour was attributed to the reduction of 1-ethylpyridinium cations to pyridyl radicals and their follow-up reactions, which influenced the zinc electrochemistry. This behaviour was further seen to modify the nucleation process of electrodeposition, which altered the morphology of zinc electrodeposits.