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Three corrosion inhibitors for copper-3-amino-1,2,4-triazole (ATA), benzotriazole (BTAH), and 1 -hydroxybenzotriazole (BTAOH)-were investigated by corrosion experiments and atomistic computer simulations. The trend of corrosion inhibition effectiveness of the three inhibitors on copper in near-neutral chloride solution is determined experimentally as BTAH ≳ ATA ⪢ BTAOH. A careful analysis of the results of computer simulations based on density functional theory allowed to pinpoint the superior inhibiting action of BTAH and ATA as a result of their ability to form strong N-Cu chemical bonds in deprotonated form. While these bonds are not as strong as the Cl-Cu bonds, the presence of solvent favors the adsorption of inhibitor molecules onto the surface due to stronger solvation of the Cl anions. Moreover, benzotriazole displays the largest affinity among the three inhibitors to form intermolecular aggregates, such as [BTA-Cu]n polymeric complex. This is another factor contributing to the stability of the protective inhibitor film on the surface, thus making benzotriazole an outstanding corrosion inhibitor for copper. These findings cannot be anticipated on the basis of inhibitors' molecular electronic properties alone, thus emphasizing the importance of a rigorous modeling of the interactions between the components of the corrosion system in corrosion inhibition studies. [ABSTRACT FROM AUTHOR]

The influence of the benzotriazole (BTAH) inhibitor on the thickness of the Cu2O oxide layer formed on Cu immersed in 3% NaCl solution was studied with angle-resolved X-ray photoelectron spectroscopy. The X-ray-induced Auger Cu L3M4,5M4,5 spectra were reconstructed with the Monte Carlo algorithm using the spectra of the basic constituents [Cu(I)BTA, Cu2O, and Cu] formed on the surface. The relative contributions of the basic constituents to the composite Cu L3M4,5M4,5 spectra measured at different emission angles were then used to estimate the thickness of the Cu2O oxide layer. The results show that the presence of BTAH substantially reduces the thickness of the Cu2O oxide layer formed on Cu in chloride media. The average thickness of the Cu2O layer below the Cu(I)BTA layer is estimated to be 1.3 ± 0.2 nm, whereas the Cu2O thickness of the noninhibited sample is 2.2 ± 0.3 nm. [ABSTRACT FROM AUTHOR]