Effects of antimony(III) on zinc electrodeposition from acidic sulfate electrolyte containing [BMIM]HSO4

Abstract

The effect of antimony(III) on the cathodic current efficiency (CE), power consumption (PC), deposit morphology, and polarization behavior during electrodeposition of zinc from acidic sulfate solutions containing 1-butyl-3-methylimidazolium hydrogen sulfate-[BMIM]HSO4 was investigated. The results indicated that the addition of Sb(III) alone decreased the CE, increased the PC, and deteriorated the quality of the zinc electrodeposits. However, the combined addition of Sb(III) and [BMIM]HSO4 was found to be beneficial for zinc deposition and improved the surface morphology of the zinc electrodeposits. Maximum CE and minimum PC were obtained at the combined addition of 0.02 mg dm−3 Sb(III) and 5 mg dm−3 [BMIM]HSO4. Depolarization of the cathode was noted in the presence of Sb(III) alone in the electrolyte whereas this effect was partly counteracted by the addition of [BMIM]HSO4. Cathodic polarization curves were traced and analyzed to determine the electrokinetic parameters such as Tafel slope, transfer coefficient, and exchange current density so as to elucidate the nature of the electrode reactions. The data obtained from X-ray diffractogram revealed that the presence of Sb(III) did not change the structure of the electrodeposited zinc but affected the crystallographic orientation of the crystal planes.