4. Conclusions
Using an EQCM, verified the mechanism for cobalt electrodeposition and correlated it with solution pH and electrochemical
conditions. The electrodeposition mechanism occurs via the direct reduction of cobalt (Eq. (1)) for a pH of 5.40 and under potentiodynamic or potentiostatic conditions. The relation valueM/z for cobalt electrodeposition at pH 5.40 under potentiodynamic and potentiostatic conditionswas equal to 32.00 and 33.00 gmol−1, respectively.
Potentiodynamic electrodeposition of cobalt at pH 2.70 occurs via the mechanism of adsorbed hydrogen, and M/z values tend towards 13.00 gmol−1. The experimental M/z relation was lower than that predicted by theory due to the hydrogen reduction reaction, which decreases the cobalt electrodeposition efficiency.Cobalt potentiostatic electrodeposition at pH2.70 occurs via simultaneous mechanisms of direct reduction and cobalt reduction in the presence of adsorbed hydrogen. The M/z value was larger for depositions accomplished at a more negative potential. This demonstrates that a more cathodic potential increases the direct cobalt reaction (Eq. (1)) contribution to the simultaneous mechanism of direct reduction.