Figure 3

Nyquist plots for the measured EIS data (symbols) and their fittings (solid lines) using the EC shown in Fig. 2 for steel in the presence of different concentrations of Q-32 (5, 10, 15 and 20 µmol L−1) and (A) 3.5 wt% NaCl solution at pH 7, (B) SCPS at pH 9, and (C) SCPS at pH 12, within a frequency range of 1 × 10–2 to 1 × 105 Hz at OCP.