Anodic behaviour and passivation of a lead electrode in sodium carbonate solutions

Electrochemical Formation of a Failure Preventing Film on Nickel Surface in Borate Solutions

“…3. It is clear that the data are well represented by a straight-line relationship within the concentration range studied, according to [22,23,26]:…”

“…This indicates that the formation of a protective passive film on Ni is controlled by the diffusion of the OHanion to the anode surface [22,23]. However, for the passive region, A 2 , a linear relationship between i A 2 and m 0.5 is observed with a small intercept, Fig.7, indicating that the rate-determining step in the formation of the protective passive film on Ni surface is not a single diffusioncontrolled process [22,23]. Further inspection of the curves of Fig.…”

“…The cathodic branches in the second and third sweeps are similar to that reported in the first sweep except that the current of the cathodic peak, C 1 , is somewhat higher. This behavior shows that the forward and backward sweeps are different indicating irreversible processes [19][20][21][22][23]. Dissimilarities between successive sweeps can be attributed to different initial states of the electrode surface.…”

“…Furthermore, the ratio of the anodic to cathodic, Q a /Q c , is always greater than 1. This indicates that part of the anodic charges is used to produce a soluble species [22,23,26].…”

“…8). Such observation might be due to a dissolution process or to the formation of difficulty reducible species [22]. At lower sweep rates, the dissolved products that formed during the anodic sweep have sufficient time to diffuse into the bulk of solution before being reduced on reversal polarization.…”