Investigation of 5-mercapto-1-phenyl-tetrazole inhibition properties by using EQCM and EC-STM techniques

The mechanism of copper corrosion and its inhibition have been studied usin g electrochemical techniques, in-situ electrochemical scanning tunneling mi croscopy (EC-STM) and electrochemical quartz crystal microbalance (EQCM) me thods. The morphological changes of Cu(111) were followed in 0.1 mol.dm(-3) Na2SO4 solution at pH=2.95. The adsorption, orientation and ordering of 5- mercapto-1-phenyl-tetrazole (5-MPhTT) at different concentrations have been studied. The anodic dissolution of copper in 0.1 mol.dm(-3) Na2SO4 was cle arly modified and hindered by the addition of 5-MPhTT. The anodic current d ensity was reduced sharply due to the adsorption of the inhibitor on the me tal surface thus providing protection. QCM data revealed that the addition of the inhibitor to the aggressive solution did not cause a continuous incr ease of the electrode mass. This fact indicates that the inhibition of copp er corrosion was due to the adsorption of a monolayer.