3. Results and discussion
3.1. Potentiodynamic and electrochemistry quartz crystalmicrobalance measurements
Measurements of the potentiodynamic electrodeposition of cobalt coupled to the EQCM technique are shown in Fig. 2. The
voltammograms curves for two different pH solutions (2.70 and 5.40) with a scan rate of 20mVs−1 appear in Fig. 2a. Correspondent mass variations on the working electrode are represented in the inset of Fig. 2b. Upon analysis of the voltammogramcurve for a pH 2.70 solution (Fig. 2a), during the scan through negative potentials, no processes were observed until a potential of −0.34V was reached. From this potential, an increase in current density was observed, reaching a maximum value of −0.46V. As shown in the inset of Fig. 2b, however, no mass variation was observed until a
potential of −0.75V was achieved. From this potential, the current density increased quickly prior to reaching the inversion potential (−1.00V), which was followed by a mass increase on the platinum electrode. The voltammogramcurve obtained for cobalt electrodeposition in a pH 5.40 solution presents similar behavior; however,during the cathodic scan, the current density begins to increase at −0.70V.