The electrochemical deposition of Zn–Mn coating from choline chloride–urea deep eutectic solvent

Electrochemical and microscopic techniques were used for the characterisation of Zn–Mn coatings electrodeposited from choline chloride–urea deep eutectic solvent. Cyclic voltammograms show that there was no discernible Mn reduction peak when only Mn²⁺ was present in DES solution. The distinct Mn peak developed only upon addition of Zn²⁺ to the solution, probably due to previous Zn nucleation on the steel substrate. It was found that 22–27 wt-% Mn deposited at current densities of 3–8 mA cm⁻², amounts significantly higher than those obtained from aqueous electrolytes. Since higher deposition current densities resulted in the formation of a porous surface consisting of clusters of nodular crystallites, the optimal deposition c.d was determined to be 3 mA cm⁻².