Behavior similar to that shown in Fig. 3 was also observed for potentiostatic electrodeposition (−1.00V), which is presented in Fig. 4. In this case,M/z values remained near 33.00 gmol−1 throughout electrodeposition in a pH5.40 solution. For the pH2.70 solution, M/z values began at approximately 12.00 gmol−1 and continued increasing up to a value of 26.00 gmol−1 at the end of the process.This M/z can be explained using simultaneousmechanisms, including the direct reduction reaction and the cobalt reduction reaction,with adsorbed hydrogen formation. Comparison of M/z values during potentiostatic electrodeposition at two different potentials (pH 2.70) revealed that M/z was larger when the deposition was performed at a more negative potential. Thus, the potential displacement for more cathodic values increased the cobalt reaction
contribution via a mechanism of direct reduction (Eq. (1)). Results obtained for potentiostatic electrodepositions suggest
that, at pH5.40, cobalt reduction occurs by a direct reductionmechanism. For cobalt electrodeposition at pH 2.70 and in the presence of the hydrogen detachment reaction, a simultaneous mechanism of direct reduction and cobalt reduction occurs.