Adsorption of 2-mercaptobenzothiazole on copper surface from phosphate solutions

Analysis of the electrochemical and XPS results has shown that adsorption of 2-mercaptobenzothiazole (MBT) on copper electrodes in neutral phosphate solutions proceeds through the formation of the chemical bonds by copper (I) cations with exo-sulfur and nitrogen atoms. A protection layer formed of Cu(I)MBT complex prevents precipitation of copper (II) phosphate on a copper surface. The thickness of the surface film consisting of a complex [Cu(I)MBT]n (having probably polymeric nature), where MBT acts as at least three-dentate ligand, increases depending on the exposure time, reaching 8-9 nm after immersing for 12 h in test solution. Even in a case of the preliminary formation of copper (II) phosphate on the copper electrode at the anodic potential addition of small amounts of MBT results in complete removal of copper (II) phosphate from the surface.

► 2-Mercaptobenzothiazole (MBT) adsorbs on copper from phosphate solutions. ► MBT forming a complex with Cu removes phosphate from the surface film. ► The formed complex [CuMBT]n completely suppresses the anodic current. ► The thickness of polymeric complex [CuMBT]n may reach 10 nm. ► The possible structure of the formed complex is discussed.