Study of Mechanisms of Cobalt Electrodeposition by Means of Potentiodynamic Polarization Curves

Abstract

The present work aims to contribute to a better understanding of the cobalt deposition onto cobalt and steel through a systematic study of experimental and theoretical potentiodynamic polarization curves. The occurrence of simultaneous reactions of reduction of hydrogen and oxygen was taken into account. The possibility of galvanic deposition was also investigated. Experimental curves were constructed from tests using cobalt and carbon steel working electrodes in electrochemical cells with electrolytes containing cobalt ions and boric acid with and without nitrogen injection. Theoretical curves were constructed based on the individual redox reactions for the considered system. For each of the reactions, the Butler–Volmer equation was analyzed, considering the occurrence of concentration polarization. By comparing the theoretical and experimental curves, a quantitative approach of the cobalt deposition on a cobalt electrode could be established. The analysis of theoretical curves for cobalt deposition on a steel electrode allowed a qualitative comparison with the experimentally obtained curves.