Adsorption behavior of dodecylamine on copper–nickel alloy surface in NaCl solutions studied by electrochemical methods and AFM

The adsorption behavior of dodecylamine on a copper–nickel alloy in 0.2 M NaCl solutions was studied by electrochemical methods and atomic force microscopy (AFM). The polarization curves showed that dodecylamine had both cathodic and anodic inhibition action, but was mainly a cathodic-type inhibitor. The results of electrochemical impedance spectroscopy (EIS) and in situ AFM phase images indicated that as the inhibitor concentration increased from 0.0005 to 0.005 M, the monolayer adsorbed film of inhibitor tended to become more ordered and denser so that corrosion inhibition efficiency tended to increase. Differential capacity curve experiments indicated that the adsorbed dodecylamine film changed the structure of the double-electric layer and made the potential of zero charge (PZC) shift to the positive direction. AFM force curve measurements were also performed and showed that as a result of the adsorption of dodecylamine on copper–nickel alloy surface, adhesive forces between the tip and the sample surface were detected and the long-range electrostatic repulsive forces between the tip and the sample surface were decreased.