DFT investigation of 2-mercaptobenzothiazole adsorption on model oxidized copper surfaces and relationship with corrosion inhibition.

• Adsorption of MBT corrosion inhibitor studied at atomic scale on oxidized copper. • DFT modelling performed on Cu(111) covered by ultrathin Cu 2 O(111) film. • Strong covalent bonding between exo cyclic sulfur atom and under coordinated Cu site. • Saturation monolayer coverage favored over single molecular low coverage adsorption. • Protective layer formed by substituting surface H 2 O and OH in aqueous environment. 2-mercaptobenzothiazole (MBT) is known as an efficient corrosion inhibitor for copper. In the present work, we performed quantum chemical DFT calculations of the interaction of MBT on Cu(111) surfaces covered by an ultrathin Cu 2 O(111) film, in order to bring atomic scale insight on the corrosion inhibition properties of MBT on oxidized copper surfaces. Thione and thiolate forms of MBT are found to interact strongly with the oxidized surfaces. The formation of a monolayer at full coverage is favored over single molecular adsorption at low coverage with the molecules adopting a perpendicular orientation. Thione binds strongly via covalent bonding between the exocyclic sulfur atom and the under coordinated Cu site, and additional H-bonding between the NH group and surface oxygen atoms (NH...O H-bond). Thiolate binds more strongly via a second covalent bond between the N atom and saturated Cu site. Bonding interaction is confirmed by the electronic structure analysis and charge transfer. The adsorption process leads to the reconstruction of the topmost oxide surface. The calculations suggest that both forms of MBT may substitute H 2 O and OH at the Cu 2 O film surface, and thus may form a protective layer on oxidized copper surfaces in aqueous environment. [ABSTRACT FROM AUTHOR]