Electrochemical deposition of zinc from zinc oxide in 2:1 urea/choline chloride ionic liquid

Abstract To overcome the major difficulties involved in the electrodeposition of zinc (Zn) from traditional aqueous solvents, it is important to discover novel electrolytes that are eco-friendly and highly efficient. Zinc oxide (ZnO) was dissolved in eutectic mixture of urea/choline chloride (2:1 molar ratio) at different temperatures (343-373K). Electrochemical measurements confirmed that the onset reduction potential for Zn2+ to Zn occur at ∼-1.05V using cyclic voltammetry. A linear relationship was obtained between cathodic peak current and square root of scan rate, thus indicating the reaction was governed by diffusion-controlled mechanism. Electrodeposition of Zn followed three dimensional (3D) instantaneous nucleation and growth mechanism for various reduction potentials. Scanning electron microscopy (SEM) images showed the formation of hexagonal-shaped Zn particles at lower applied potentials, while plate-like structures of Zn metal were deposited at higher applied potentials. The X-ray diffraction (XRD) and energy dispersive spectroscopy (EDS) analysis confirmed the presence of high-pure Zn metal electrodeposits on Cu cathode.