Electrolytic deposition of Zn coatings from ionic liquids based on choline chloride

Reported here are results of a systematic study into the electrolytic deposition of Zn metal from ionic liquids based on eutectic mixtures of choline chloride (ChCl) with either ethylene glycol (Eg) or urea. Cyclic voltammetry and gravimetric acoustic impedance spectroscopy (EQCM) techniques have been used to probe mass-transfer and charge-transfer mechanisms. The results show that nucleation in the urea based liquid is fast but bulk growth is slow, whereas nucleation in the glycol based liquid is slow but bulk growth is relatively fast. Critical surface coverage necessary for the transition from nucleation to bulk growth is similar for both liquids. Additionally, ex situ atomic force microscopy (AFM) has been used to probe the morphology of the metallic deposit at two different potentials during a linear sweep voltammogram.