Adsorption and thermal stability of 2-mercaptobenzothiazole corrosion inhibitor on metallic and pre-oxidized Cu(1 1 1) model surfaces

Abstract 2-mercaptobenzothiazole (2-MBT) is used for its corrosion inhibition properties. In this study, the adsorption of 2-MBT on metallic and pre-oxidized Cu(1 1 1) surfaces was investigated using Auger Electron Spectroscopy and Scanning Tunneling Microscopy. Growth and structure of molecular films adsorbed at ultra low pressure and room temperature on clean and pre-oxidized Cu(1 1 1) surfaces were characterized. On clean metallic Cu(1 1 1) surface, local triangular ( 7 × 7 ) R19.1° structures are formed at low exposures (3–4 L), which are assigned to the adsorption of atomic S resulting from partial decomposition of 2-MBT. At 10 L, a full non-ordered monolayer of 2-MBT is formed, and further exposure leads to the formation of a non-ordered multilayer. The thickness of the outermost 2-MBT layer is 1.3 A, which suggests that the outermost molecules of the multilayer are lying flat. Oxidation of the copper surface prior to exposure to 2-MBT results in more compact and homogeneous molecular films. The initial 2D oxide is dissociated and replaced by 2-MBT. Thermal stability at different temperatures was studied on clean and pre-oxidized copper surfaces saturated with 2-MBT. A ( 7 × 7 ) R19.1° structure is observed in both cases for temperatures higher than 100 ° C, indicating the decomposition of 2-MBT and a copper surface covered with atomic S.