Ionic Liquid [BMPy]Br as an Effective Additive During Zinc Electrodeposition from an Aqueous Sulfate Bath

Abstract

The effects of a new ionic liquid additive 1-butyl-3-methylpyridinium bromide [BMPy]Br on the electrodeposition of zinc on steel substrates from acidic sulfate solution was investigated by employing potentiodynamic polarization and cyclic voltammetry techniques complemented with XRD and SEM measurements. Kinetic parameters such as the Tafel slope, transfer coefficient and exchange current density obtained from Tafel plots, indicated that [BMPy]Br had a pronounced inhibiting effect on Zn+2 electroreduction and led to more leveled and fine-grained deposits, especially at low concentrations. In addition, [BMPy]Br was found to improve the throwing power as well as the throwing index of the electrolytic solution. Data obtained from x-ray diffraction spectra revealed that the presence of this additive did not change the crystal structure of the electrodeposited zinc but strongly affected the crystallographic orientation of the crystal planes.