Electrochemical behaviour of an inhibitor film formed on copper surface

The potential dependence of adsorption and kinetic properties of inhibitor film formation on copper surface was studied in acidic environment by using surface sensitive techniques: electrochemical quartz crystal microbalance (EQCM) and electrochemical scanning tunneling microscopy (EC-STM). The investigated inhibitor was 5-mercapto-1-phenyl-tetrazole (5-MPhTT) in 1 mmol dm⁻³ H₂SO₄ solution. The QCM investigations were done to study the electrode mass changes in absence and presence of 5-MPhTT at rest potential. The apparent mass and current variation as a function of the electrode potential was registered in order to study the protective film and its breakdown. Results revealed that the anodic current density and the electrode mass loss is twice less in presence of 5-MPhTT. We also present results of an in situ STM study on the surface morphology and anodic dissolution of Cu(1 1 1) electrodes in inhibited/uninhibited electrolytes. The images gave information about the nature of the protective layer. The results were analyzed and discussed.