The Catalytic Role of L-cysteine During Electrolytic Zinc Deposition

Document Type : Original Article


1 Dar Masr ,Al-Andalus, New Cairo. Cairo

2 Ain Shams University, Faculty of Science, Chemistry Department Cairo, Egypt

3 Chemistry Department, Faculty of Science, Al-Azhar University, Cairo, Egyp

4 Chemistry department, Faculty of Science, Ain Shams University


In this study, utilizing L-Cys as a complexing agent in an acid-sulphate zinc bath led to significant improvements. Using cathodic current efficacy, polarization curves, in situ anodic linear stripping voltammetry, i-t transient, and macrothrowing power, it has been determined how Cys affects zinc electrodeposition from a sulphate solution. Due to L-Cys' catalytic impact on the reduction of Zn+2 ions, the i-E curve and potential of zinc deposition significantly move in the direction of more positive values when L-Cys is present. The kinetic data show that in the existence of Cys, both the Tafel slope (βC) and the exchange current (io) are higher (496.1– 616.3 mV decade−1), (0.0034 Acm-2) than without Cys (429.2 mV decade−1), (0.0017 Acm-2) respectively. As the concentration of L-Cys rises, the exchange current density significantly increases. Moreover, the limiting current was greatly increased by the existence of L-Cys. The consistent values of the transfer coefficient αc, however, suggest that the presence of Cys has no effect on the Zn electrodeposition process. Both the Wagner number and the macrothrowing power are reduced with the inclusion of Cys. The surface appearance and composition of zinc deposits have been examined using SEM and EDX in the present and absent Cys.